CUBIST PHARMACEUTICALS INC
S-1/A, 1996-09-17
PHARMACEUTICAL PREPARATIONS
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<PAGE>
 
   
AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON SEPTEMBER 17, 1996     
 
                                                       REGISTRATION NO. 333-6795
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
 
                                --------------
 
                                 PRE-EFFECTIVE
                                 
                              AMENDMENT NO. 2     
                                       TO
 
                                    FORM S-1
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                                --------------
 
                          CUBIST PHARMACEUTICALS, INC.
             (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
                         CUBIST PHARMACEUTICALS, INC.
            (EXACT NAME OF REGISTRANT AS SPECIFIED IN ITS CHARTER)
 
        DELAWARE                     2834                    22-3192085
     (STATE OR OTHER           (PRIMARY STANDARD          (I.R.S. EMPLOYER
     JURISDICTION OF              INDUSTRIAL             IDENTIFICATION NO.)
    INCORPORATION OR          CLASSIFICATION CODE
      ORGANIZATION)                 NUMBER)
 
                                24 EMILY STREET
                              CAMBRIDGE, MA 02139
                                 (617) 576-1999
  (ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE, OF
                   REGISTRANT'S PRINCIPAL EXECUTIVE OFFICES)
 
                                --------------
 
                            SCOTT M. ROCKLAGE, PH.D.
                     PRESIDENT AND CHIEF EXECUTIVE OFFICER
                          CUBIST PHARMACEUTICALS, INC.
                                24 EMILY STREET
                              CAMBRIDGE, MA 02139
                                 (617) 576-1999
 (NAME, ADDRESS, INCLUDING ZIP CODE, AND TELEPHONE NUMBER, INCLUDING AREA CODE,
                             OF AGENT FOR SERVICE)
 
                                --------------
 
                                WITH COPIES TO:
       JUSTIN P. MORREALE, ESQ.                STEVEN D. SINGER, ESQ.
          JULIO E. VEGA, ESQ.                VIRGINIA H. KINGSLEY, ESQ.
       BINGHAM, DANA & GOULD LLP                    HALE AND DORR
          150 FEDERAL STREET                       60 STATE STREET
           BOSTON, MA 02110                       BOSTON, MA 02109
            (617) 951-8000                         (617) 526-6000
                                --------------
   
  APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO THE PUBLIC: As soon as
practicable after this Registration Statement becomes effective.     
   
  If any of the securities being registered on this Form are to be offered on a
delayed or continuous basis pursuant to Rule 415 under the Securities Act of
1933, check the following box. [_]     
   
  If this Form is filed to register additional securities for an offering
pursuant to Rule 426(b) under the Securities Act, please check the following
box and list the Securities Act registration statement number of the earlier
effective registration statement for the same offering. [_]     
   
  If this Form is a post-effective amendment filed pursuant to Rule 426(c)
under the Securities Act, check the following box and list the Securities Act
registration statement number of the earlier effective registration statement
for the same offering. [_]     
   
  If delivery of the prospectus is expected to be made pursuant to Rule 434,
please check the following box. [_]     
                         
                      CALCULATION OF REGISTRATION FEE     
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<TABLE>   
<CAPTION>
                                              PROPOSED        PROPOSED
                                AMOUNT        MAXIMUM          MAXIMUM
  TITLE OF EACH CLASS OF         TO BE     OFFERING PRICE     AGGREGATE          AMOUNT OF
SECURITIES TO BE REGISTERED  REGISTERED(1)  PER SHARE(2)  OFFERING PRICE(2) REGISTRATION FEE(3)
- -----------------------------------------------------------------------------------------------
<S>                          <C>           <C>            <C>               <C>
Common Stock, $.001 par
 value.................        2,300,000       $12.00        $27,600,000          $9,517
</TABLE>    
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
   
(1) Includes up to 300,000 shares of Common Stock which the Underwriters have
    the option to purchase from the Company to cover over-allotments, if any.
           
(2) Estimated solely for the purpose of determining the registration fee in
    accordance with Rule 457 under the Securities Act of 1933.     
   
(3) Previously paid in connection with the initial filing of the Registration
    Statement.     
 
                                --------------
  THE REGISTRANT HEREBY AMENDS THIS REGISTRATION STATEMENT ON SUCH DATE OR
DATES AS MAY BE NECESSARY TO DELAY ITS EFFECTIVE DATE UNTIL THE REGISTRANT
SHALL FILE A FURTHER AMENDMENT WHICH SPECIFICALLY STATES THAT THIS REGISTRATION
STATEMENT SHALL THEREAFTER BECOME EFFECTIVE IN ACCORDANCE WITH SECTION 8(A) OF
THE SECURITIES ACT OF 1933 OR UNTIL THE REGISTRATION STATEMENT SHALL BECOME
EFFECTIVE ON SUCH DATE AS THE COMMISSION, ACTING PURSUANT TO SAID SECTION 8(A),
MAY DETERMINE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
  CROSS REFERENCE SHEET BETWEEN ITEMS IN PART I OF FORM S-1 AND THE PROSPECTUS
 
<TABLE>
<CAPTION>
      REGISTRATION STATEMENT
      ITEM NUMBER AND CAPTION                  CAPTION IN PROSPECTUS
      -----------------------                  ---------------------
<S>                                 <C>
 1.Forepart of the Registration
     Statement and Outside Front
     Cover Page of Prospectus...... Outside Front Cover Page of Prospectus
 2.Inside Front and Outside Back
     Cover Pages of Prospectus..... Inside Front and Outside Back Cover Pages
                                     of Prospectus
 3.Summary Information and Risk
     Factors....................... Prospectus Summary; Risk Factors
 4.Use of Proceeds................. Prospectus Summary; Use of Proceeds
 5.Determination of Offering        Outside Front Cover Page of Prospectus;
     Price.........................  Risk Factors; Underwriting
 6.Dilution........................ Risk Factors; Dilution
 7.Selling Security Holders........ Not Applicable
 8.Plan of Distribution............ Outside Front and Inside Front Cover Page
                                     of Prospectus; Underwriting
 9.Description of Securities to be  
     Registered.................... Outside Front Cover Page of Prospectus;
                                     Prospectus Summary; Dividend Policy;
                                     Capitalization; Description of Capital
                                     Stock
10.Interests of Named Experts and
     Counsel....................... Legal Matters; Experts
11.Information with Respect to      
     Registrant....................  Outside Front and Inside Front Cover Pages;
                                     Prospectus Summary; Risk Factors; Dividend
                                     Policy; Capitalization; Selected Financial
                                     Data; Management's Discussion and Analysis
                                     of Financial Condition and Result of
                                     Operations; Business; Management; Certain
                                     Transactions; Principal Stockholders;
                                     Description of Capital Stock; Shares
                                     Eligible for Future Sale; Experts;
                                     Financial Statements
12.Disclosure of Commission
     Position on Indemnification
     for Securities Act
     Liabilities................... Not Applicable
</TABLE>
<PAGE>
 
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
+INFORMATION CONTAINED HEREIN IS SUBJECT TO COMPLETION OR AMENDMENT. A         +
+REGISTRATION STATEMENT RELATING TO THESE SECURITIES HAS BEEN FILED WITH THE   +
+SECURITIES AND EXCHANGE COMMISSION. THESE SECURITIES MAY NOT BE SOLD NOR MAY  +
+OFFERS TO BUY BE ACCEPTED PRIOR TO THE TIME THE REGISTRATION STATEMENT        +
+BECOMES EFFECTIVE. THIS PROSPECTUS SHALL NOT CONSTITUTE AN OFFER TO SELL OR   +
+THE SOLICITATION OF AN OFFER TO BUY NOR SHALL THERE BE ANY SALE OF THESE      +
+SECURITIES IN ANY STATE IN WHICH SUCH OFFER, SOLICITATION OR SALE WOULD BE    +
+UNLAWFUL PRIOR TO REGISTRATION OR QUALIFICATION UNDER THE SECURITIES LAWS OF  +
+ANY SUCH STATE.                                                               +
++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
                 
              Subject to Completion, Dated September 17, 1996     
 
PROSPECTUS
                                
                             2,000,000 SHARES     
                                      
                                   LOGO     
 
                          CUBIST PHARMACEUTICALS, INC.
 
                                  COMMON STOCK
 
                                 -------------
   
  All of the 2,000,000 shares of Common Stock offered hereby are being sold by
Cubist Pharmaceuticals, Inc. ("Cubist" or the "Company"). Prior to this
Offering, there has been no public market for the Common Stock of the Company.
It is currently estimated that the initial public offering price will be
between $10.00 and $12.00 per share. See "Underwriting" for a discussion of the
factors to be considered in determining the initial public offering price.
Application has been made to have the Common Stock approved for quotation on
the Nasdaq National Market under the symbol "CBST."     
 
  THE COMMON STOCK OFFERED HEREBY INVOLVES A HIGH DEGREE OF RISK. SEE "RISK
FACTORS," BEGINNING ON PAGE 6.
 
                                 -------------
 
 THESE SECURITIES HAVE NOT BEEN APPROVED  OR DISAPPROVED BY THE SECURITIES AND
   EXCHANGE COMMISSION OR ANY OTHER  STATE SECURITIES COMMISSION NOR HAS  THE
    SECURITIES AND  EXCHANGE COMMISSION OR ANY  STATE SECURITIES COMMISSION
      PASSED UPON  THE  ACCURACY  OR  ADEQUACY  OF  THIS  PROSPECTUS.  ANY
       REPRESENTATION TO THE CONTRARY IS A CRIMINAL OFFENSE.
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<TABLE>
<CAPTION>
                                   Price to   Underwriting Discounts Proceeds to
                                    Public      and Commissions(1)   Company(2)
- --------------------------------------------------------------------------------
<S>                               <C>         <C>                    <C>
Per Share.......................    $                $                 $
- --------------------------------------------------------------------------------
Total(3)........................  $                 $                $
</TABLE>
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
(1) For information regarding indemnification of the Underwriters, see
    "Underwriting."
 
(2) Before deducting expenses of the Offering payable by the Company, estimated
    at $600,000.
   
(3) The Company has granted the Underwriters an option, exercisable within 30
    days from the date hereof, to purchase up to 300,000 additional shares of
    Common Stock on the same terms as set forth above, solely to cover over-
    allotments, if any. If such option is exercised in full, the total Price to
    Public will be $   , the Underwriting Discounts and Commissions will be
    $   , and the Proceeds to Company will be $   . See "Underwriting."     
 
                                 -------------
 
  The shares of Common Stock offered by the Underwriters are subject to prior
sale, receipt and acceptance by them and subject to the right of the
Underwriters to reject any order in whole or in part and to certain other
conditions. It is expected that delivery of the shares of Common Stock will be
made through the offices of UBS Securities LLC, 299 Park Avenue, New York, New
York on or about       , 1996.
 
                                 -------------
 
UBS SECURITIES
 
                  HAMBRECHT & QUIST
 
                                                   PACIFIC GROWTH EQUITIES, INC.
 
    , 1996
<PAGE>
 
Current antiinfective drugs are           Protein synthesis is a sequential  
categorized  according to the four        process essential to the life of the 
types of essential cell functions         cell whereby amino acids are   
they inhibit:  (i) protein synthesis,     incorporated into proteins.  Cubist 
(ii) cell metabolism, (iii) cell wall     focuses on discovering novel anti-
synthesis and (iv) nucleic acid           infective drugs that inhibit new
synthesis.                                targets essential to protein 
                                          synthesis.  These targets are shown
                       (i) Protein        in the boxes below.
                           Synthesis

                 (ii) Cell                     Ribonuclease P
                      Metabolism

       (iii) Cell Wall                    [PICTURE OF RIBONUCLEASE 
             Synthesis      Ribosomes      P AND tRNA APPEARS HERE] 
                           
(iv) Nucleic Acid       [PICTURE OF        
     Synthesis       CELL AND             Immature             Mature
                  CELL FUNCTION           tRNA                 tRNA
               APPEARS HERE]

           Enzyme
                                                Ribonuclease P (RNase P)
        DNA                                     binds to and cleaves immature
                                                tRNA molecules to produce
                                                mature tRNAs.


mRNA        Synthetase      Amino                    Amidotransferase
                            Acid                             Glutamine

    [PICTURE OF AMINOACYL tRNA                  [PICTURE OF AMIDOTRANSFERASE
    SYNTHETASE CHARGING APPEARS                 MODIFYING GLUTAMATE tRNA
    HERE]                                       APPEARS HERE]   
                        Charged                                        Glutamine
                        tRNA
                                                Certain bacteria lack glutamine
Aminoacyl tRNA synthetase binds to              tRNA synthetase and require
mature tRNA and charges it with a               amidotransferase (AdTase) to
specific amino acid.                            bind to an inappropriately
                                                charged tRNA and modify the 
         EF-Tu                                  amino acid glutamate to 
                                                glutamine.




[PICTURE OF ELONGATION FACTOR                                       Protein
Tu AND CHARGED tRNA APPEARS HERE]                                            
                                                 [PICTURE OF CHARGED tRNA,   
                                                 RIBOSONE,mRNA, AND PROTEIN
Elongation factor EF-Tu binds to                 CHAIN APPEARS HERE]         
charged tRNA and transports it to
the ribosome for protein synthesis.                                 mRNA
                                              Ribosome

                               ----------------
 
  IN CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR EFFECT
TRANSACTIONS WHICH STABILIZE OR MAINTAIN THE MARKET PRICE OF THE COMMON STOCK
OF THE COMPANY AT A LEVEL ABOVE THAT WHICH MIGHT OTHERWISE PREVAIL IN THE OPEN
MARKET. SUCH TRANSACTIONS MAY BE EFFECTED ON THE NASDAQ NATIONAL MARKET, IN
THE OVER-THE-COUNTER MARKET OR OTHERWISE. SUCH STABILIZING, IF COMMENCED, MAY
BE DISCONTINUED AT ANY TIME.


<PAGE>
 
                               PROSPECTUS SUMMARY
 
  The following summary is qualified in its entirety by the more detailed
information and the Financial Statements and Notes thereto appearing elsewhere
in this Prospectus, including the information under "Risk Factors." This
Prospectus contains forward-looking statements which involve risks and
uncertainties. The Company's actual results may differ significantly from the
results discussed in the forward-looking statements. Factors that might cause
such a difference include, but are not limited to, those discussed under "Risk
Factors."
 
                                  THE COMPANY
 
  Cubist Pharmaceuticals, Inc. ("Cubist" or the "Company") is a
biopharmaceutical company engaged in the research, development and
commercialization of novel antiinfective drugs to treat infectious diseases
caused by bacteria and fungi, primarily those resistant to existing
antiinfective drugs. The increasing prevalence of drug-resistant bacterial and
fungal pathogens has led to significantly higher mortality rates from
infectious diseases and currently presents a serious crisis worldwide. Cubist's
strategy for combating antiinfective drug resistance is to identify novel
intracellular targets essential for cell function in bacteria and fungi, such
as proteins, RNA or DNA, which if inhibited by a drug would kill or attenuate
the growth of the pathogen. Cubist selects these targets based on a thorough
understanding of their function, thereby providing a foundation for assay
development and identification of leads for drug discovery.
 
  Cubist believes that its rational, target-based, drug discovery strategy
represents a distinct departure from and offers significant advantages over
traditional drug discovery strategies to counter drug resistance. These
traditional strategies have generally involved (i) whole-cell screening
methodologies which provide only limited knowledge of target function, (ii)
chemical modifications of existing antiinfective drugs, such as penicillin, or
(iii) the combination of existing antiinfective drugs with another agent (an
"antibiotic potentiator") to block drug resistance. For decades, antiinfective
drug discovery research has utilized only a fixed number of targets and
chemical structures, thereby limiting the ability of these approaches to
identify new classes of drugs effective against drug-resistant bacteria and
fungi. Cubist believes that the identification of new drug classes inhibiting
new targets will provide a compelling solution to drug resistance. The Company
has identified over 100 proprietary targets and related assays for the
discovery of new drugs. The Company expects that drugs inhibiting these new
targets will be immediately effective against drug-resistant bacteria and fungi
since these pathogens have not had an opportunity to evolve resistance specific
to these new drugs. Furthermore, Cubist's most advanced drug discovery program
could identify a drug which inhibits more than one essential target for a given
pathogen, which would significantly decrease the rate of emergence of drug
resistance.
 
  The increasing prevalence of and rise in mortality rates from infectious
diseases places additional stress on the already overburdened U.S. health care
system. According to estimates from the U.S. Centers for Disease Control and
Prevention (the "CDC"), infectious diseases ranked as the third leading cause
of death in 1992, with mortality rates increasing by 58% during the period from
1980 to 1992, in contrast to mortality rates due to all causes which decreased
by 3% during this period. Based on CDC estimates, approximately two million
hospital-acquired infections occur each year, causing more than eight million
days of extended hospital stay and resulting in more than $4.5 billion in
additional health care costs each year.
 
  According to 1995 sales data compiled by IMS International, an independent
pharmaceutical research firm, antiinfective drugs generated $26 billion in
sales and constituted the third largest pharmaceutical market worldwide, behind
only gastrointestinal and cardiovascular drugs. The growth of the worldwide
antiinfective drug market from 1994 to 1995 was 13%. Of the 100 best-selling
brand name drugs worldwide, 19 are antiinfective drugs addressing bacterial and
fungal infections. In the United States, sales of antiinfective drugs totaled
over $7 billion in 1995, and brand name antiinfective drugs accounted for 15 of
the leading 100 prescription drugs.
 
  Cubist's initial focus is on the identification and development of
antiinfective drugs to inhibit selected targets involved in the essential
process of protein synthesis. Cubist's programs are based on targets that are
responsible for the: (i) addition or charging of amino acids to tRNA molecules
by enzymes known as aminoacyl-tRNA synthetases (the "Synthetase Program"), (ii)
cleavage of immature tRNA to form mature tRNA prior to its charging with amino
acids by the enzyme ribonuclease P (the "Ribonuclease P Program"), (iii)
modification of the amino acid glutamate to
 
                                       3
<PAGE>
 
glutamine on incorrectly charged tRNAs by the enzyme amidotransferase (the
"Amidotransferase Program") and (iv) transport of amino acid-charged tRNA
molecules to the site of protein synthesis by elongation factors (the
"Elongation Factors Program"). The Company believes that its target-based
programs will enable the development of clinically effective drugs to treat
infectious diseases caused by pathogens such as staphylococci, enterococci,
streptococci and candida. To date, the Company has identified lead candidates
targeting certain aminoacyl-tRNA synthetases, which demonstrate potency and
selectivity and inhibit the growth of bacteria or fungi. Cubist expects to
complete optimization of these lead candidates and select its first drug
candidate for pre-clinical development by the end of 1996. Assuming successful
pre-clinical development, the Company expects to file an Investigational New
Drug ("IND") application by the end of 1997.
 
  A key element of the Company's strategy is to enhance certain of its drug
discovery and development programs and to fund its capital requirements, in
part, by entering into collaborative agreements with major pharmaceutical
companies. To date, the Company has entered into agreements based on certain
targets within the Synthetase Program with Bristol-Myers Squibb Company, Merck
& Co., Inc. and Pfizer Inc. Assuming that these collaborative agreements
continue until their scheduled expirations, and that a separate drug is
successfully developed and commercialized from each of the five research
programs to be conducted pursuant to these agreements, Cubist will be entitled
to receive a total of $98.5 million in research support payments, technology
licensing fees, milestone payments and equity investments. In addition, the
Company will be entitled to receive royalties on worldwide sales of any drug
developed and commercialized from the collaborations.
 
  Bristol-Myers Squibb. Cubist is collaborating with Bristol-Myers Squibb
Company ("Bristol-Myers Squibb") to discover antibacterial, antimycobacterial
and antifungal drug candidates from leads detected in the screening of Bristol-
Myers Squibb's compound library against six of Cubist's aminoacyl-tRNA
synthetase targets. If a separate drug is successfully developed and
commercialized through each of the bacterial, mycobacterial and fungal programs
within this collaboration, Cubist will be entitled to receive a total of $56.5
million in research support payments, technology licensing fees, milestone
payments and other payments from Bristol-Myers Squibb, including an equity
investment of $4.0 million made in June 1996. In addition, the Company will be
entitled to receive royalties on worldwide sales of any drug developed and
commercialized from this collaboration.
 
  Merck. Cubist is collaborating with Merck & Co., Inc. ("Merck") to discover
antibacterial drug candidates from leads detected in the screening of Merck's
compound library against three of Cubist's aminoacyl-tRNA synthetase targets.
If a drug is successfully developed and commercialized through this
collaboration, Cubist will be entitled to receive a total of $20.5 million in
research support payments, technology licensing fees, milestone payments and
other payments from Merck. In addition, the Company will be entitled to receive
royalties on worldwide sales of any drug developed and commercialized from this
collaboration.
 
  Pfizer. Cubist is collaborating with Pfizer Inc ("Pfizer") to discover
antibacterial drug candidates from leads detected in the screening of Pfizer's
compound library against six of Cubist's aminoacyl-tRNA synthetase targets. If
a drug is successfully developed and commercialized through this collaboration,
Cubist will be entitled to receive a total of $21.5 million in research support
payments, technology licensing fees, milestone payments and other payments from
Pfizer, including a $5.0 million equity investment. In addition, the Company
will be entitled to receive royalties on worldwide sales of any drug developed
and commercialized from this collaboration.
 
  Apart from these collaborations, Cubist has retained rights to internally
develop and commercialize certain proprietary products which will enable the
Company either to commercialize certain drug candidates independently, or to
enter into future drug development and commercialization alliances with third
parties at a later stage in the development process.
 
  The Company was incorporated under the laws of the State of Delaware on May
1, 1992. The Company's principal executive offices are located at 24 Emily
Street, Cambridge, Massachusetts 02139, and its telephone number is (617) 576-
1999.
 
                                --------------
 
  Cubist(TM), Cubist Pharmaceuticals(TM) and the Cubist logo are trademarks of
the Company. All other trademarks and trade names referenced in this Prospectus
are the property of their respective owners.
 
                                       4
<PAGE>
 
                                  THE OFFERING
 
<TABLE>   
<S>                                              <C>
Common Stock Offered............................ 2,000,000 shares
Common Stock Outstanding after this Offering.... 8,373,023 shares(1)
Use of Proceeds................................. To fund research and development and working
                                                 capital and for general corporate purposes.
Proposed Nasdaq National Market Symbol.......... CBST
Risk Factors.................................... The Common Stock offered hereby involves a high
                                                 degree of risk. See "Risk Factors."
</TABLE>    
 
                             SUMMARY FINANCIAL DATA
                     (in thousands, except per share data)
 
<TABLE>   
<CAPTION>
                                                                 SIX MONTHS
                                  YEARS ENDED DECEMBER 31,     ENDED JUNE 30,
                                 ----------------------------  ----------------
                                   1993      1994      1995     1995     1996
                                 --------  --------  --------  -------  -------
<S>                              <C>       <C>       <C>       <C>      <C>
STATEMENTS OF OPERATIONS DATA:
Sponsored research revenues....  $    --   $    --   $  1,271  $   100  $ 2,047
Total operating expenses.......     1,716     4,758     6,673    3,414    4,056
Net interest income (expense)..        28       (55)        6      (10)     (64)
                                 --------  --------  --------  -------  -------
Net loss.......................   $(1,688)  $(4,813)  $(5,396) $(3,324) $(2,073)
                                 ========  ========  ========  =======  =======
Pro forma net loss per
 share(2)......................                      $  (0.91)          $ (0.32)
                                                     ========           =======
Pro forma weighted average
 shares used in computing
 pro forma net loss per
 share(2)......................                         5,898             6,449
</TABLE>    
 
<TABLE>   
<CAPTION>
                                                           JUNE 30, 1996
                                                      ------------------------
                                                       ACTUAL   AS ADJUSTED(3)
                                                      --------  --------------
<S>                                                   <C>       <C>
BALANCE SHEET DATA:
Cash, cash equivalents and investments............... $  4,732     $ 24,592
Working capital......................................    5,023       24,883
Total assets.........................................   10,355       30,215
Long-term debt and capital lease obligations, less
 current portion.....................................    1,206        1,206
Accumulated deficit..................................  (14,005)     (14,005)
Total stockholders' equity...........................    6,790       26,650
</TABLE>    
- -------
   
(1) Based on the number of shares outstanding as of June 30, 1996. Excludes (i)
    an aggregate of 520,660 shares of Common Stock issuable pursuant to stock
    options outstanding as of June 30, 1996, at a weighted average exercise
    price per share of $1.37, (ii) 86,619 shares of Common Stock issuable
    pursuant to warrants outstanding as of June 30, 1996, at a weighted average
    exercise price per share of $4.04, and (iii) Common Stock that may be
    issued after the closing of this Offering to Bristol-Myers Squibb pursuant
    to certain antidilution rights of Bristol-Myers Squibb.     
 
(2) Computed on the basis described in Note B of the Notes to Financial
    Statements.
   
(3) As adjusted to reflect the sale of 2,000,000 shares of Common Stock offered
    hereby and receipt by the Company of the estimated net proceeds therefrom,
    based upon an assumed initial public offering price of $11.00 per share and
    after deducting the underwriting discount and estimated offering expenses
    payable by the Company. See "Use of Proceeds" and "Capitalization."     
 
                                --------------
   
  Unless otherwise indicated, all information in this Prospectus (i) assumes
the Underwriters' over-allotment option is not exercised, (ii) reflects a one-
for-seven reverse stock split of the Common Stock to be effected prior to the
date of this Prospectus, (iii) reflects the conversion upon the closing of this
Offering of all outstanding shares of the Company's Preferred Stock into an
aggregate of 5,366,869 shares of Common Stock and of all outstanding warrants
to purchase shares of Preferred Stock into warrants to purchase 86,619 shares
of Common Stock, (iv) excludes Common Stock that may be issued after the
closing of this Offering to Bristol-Myers Squibb pursuant to certain
antidilution rights of Bristol-Myers Squibb, (v) reflects the amendment and
restatement of the Company's Amended and Restated 1993 Stock Option Plan
effective upon the closing of this Offering, (vi) reflects the amendment and
restatement of the Company's Amended and Restated By-Laws effective upon the
closing of this Offering and (vii) reflects the amendment of the Company's
Restated Certificate of Incorporation prior to the date of this Prospectus. See
"Capitalization," "Description of Capital Stock" and "Underwriting."     
 
                                       5
<PAGE>
 
                                 RISK FACTORS
 
  Prospective investors in the shares offered hereby should carefully consider
the following risk factors, in addition to the other information appearing in
this Prospectus.
 
  Early Stage of Product Development; No Assurance of Successful
Commercialization. Since inception, the Company has generated no revenue from
product sales. The Company's research and development programs are at an early
stage, and the Company does not expect that any drugs resulting from its
research and development efforts, or from the joint efforts of the Company and
its collaborative partners, will be commercially available for a significant
number of years, if at all. The Company is currently in the process of
optimizing lead candidates to select drug candidates for pre-clinical
development; however, to date, the Company has not, independently or with its
collaborative partners, completed the optimization of any lead candidates or
selected any drug candidates. Any future drug candidates developed by the
Company will require significant additional research and development efforts,
including extensive pre-clinical (animal and in vitro data) and clinical
testing and regulatory approval, prior to commercial sale. None of the
Company's potential drug candidates have advanced to any phase of pre-clinical
or clinical trials. There can be no assurance that the Company's approach to
drug discovery, acting independently or with the efforts of any collaborative
partner of the Company, will be effective or will result in the development of
any drug. The Company's potential drug candidates will be subject to the risks
of failure inherent in the development of pharmaceutical products based on new
technologies. These risks include the possibilities that any or all of the
Company's drug candidates will be found to be unsafe, ineffective or toxic or
otherwise fail to meet applicable regulatory standards or receive necessary
regulatory clearances; that these drug candidates, if safe and effective, will
be difficult to develop into commercially viable drugs or to manufacture on a
large scale or will be uneconomical to market; that proprietary rights of
third parties will preclude the Company from marketing such drugs; or that
third parties will market superior or equivalent drugs. The failure to develop
safe, commercially viable drugs would have a material adverse effect on the
Company's business, operating results and financial condition.
 
  Uncertainty Due To Unproven Technology. The Company's drug discovery
approach faces technical issues which have not been resolved and requires the
development of multiple novel technologies to create a successful drug
candidate. While the Company has demonstrated that certain compounds have the
ability to inhibit the activity of certain aminoacyl-tRNA synthetases, the
Company has not proven that this activity can be utilized clinically as a
therapeutic. Furthermore, there can be no assurance that the inhibitory
activity already demonstrated in primary screening will continue to be
encouraging in further screening or drug discovery studies. The Company has
not tested any drug candidates in humans, and there can be no assurance that
there will be clinical benefits associated with any such drug candidates.
Furthermore, there can be no assurance that the Company will successfully
address these technological challenges or others that may arise in the course
of development. Any failure of the Company to anticipate or respond adequately
to technological developments will have a material adverse effect on the
Company's business, operating results and financial condition. There can be no
assurance that the study of antiinfectives will lead to the discovery and
development of any drug candidates in the future or that the Company will be
able to employ its drug discovery approach successfully.
 
  Dependence on Collaborative Partners and Others. A key element of the
Company's strategy is to enhance certain of its drug discovery and development
programs and to fund its capital requirements, in part, by entering into
collaborative agreements with major pharmaceutical companies. In December
1995, the Company entered into a Research Collaboration Agreement with Pfizer
(the "Pfizer Agreement"), and in June 1996, the Company entered into a
Collaborative Research and License Agreement with Bristol-Myers Squibb (the
"Bristol-Myers Squibb Agreement") and a Collaborative Research and License
Agreement with Merck (the "Merck Agreement" and, together with the Pfizer
Agreement and the Bristol-Myers Squibb Agreement, the "Collaborative
Agreements"). Under the Collaborative Agreements, each of Bristol-Myers
Squibb, Merck and Pfizer is responsible for (i) providing libraries of
compounds for screening against certain of the Company's aminoacyl-tRNA
synthetase targets, (ii) selecting, in collaboration with Cubist, compounds
determined to be leads in the screening for subsequent development, (iii)
conducting preclinical and clinical trials and obtaining required regulatory
approvals of drug candidates, and (iv) manufacturing and commercializing
resulting drugs. As a result, the Company's receipt of revenues (whether in
the form of
 
                                       6
<PAGE>
 
continued research funding, drug development milestones or royalties on sales)
under the Collaborative Agreements is dependent upon the decisions made by and
the manufacturing and marketing resources of its collaborative partners. The
Company's collaborative partners are not obligated to develop or commercialize
any drug candidates resulting from the Collaborative Agreements. The amount
and timing of resources dedicated by the Company's collaborative partners to
their respective collaborations with the Company is not within the Company's
control. Moreover, certain drug candidates discovered by the Company may be
viewed by the Company's collaborative partners as competitive with such
partners' drugs or drug candidates. Accordingly, there can be no assurance
that the Company's collaborative partners will elect to proceed with the
development of drug candidates which the Company believes to be promising or
that they will not pursue their existing or alternative technologies in
preference to such drug candidates. There can be no assurance that the
interests of the Company will continue to coincide with those of its
collaborative partners, that some of the Company's collaborative partners will
not develop independently or with third parties drugs that could compete with
drugs of the types contemplated by the Collaborative Agreements, or that
disagreements over rights or technology or other proprietary interests will
not occur.
 
  If any of the Company's collaborative partners breaches or terminates its
agreement with the Company, or otherwise fails to conduct its collaborative
activities in a timely manner, the development or commercialization of any
drug candidate or research program under these Collaborative Agreement may be
delayed, the Company may be required to undertake unforeseen additional
responsibilities or to devote unforeseen additional resources to such
development or commercialization, or such development or commercialization
could be terminated. Any such event could materially adversely affect the
Company's financial condition, intellectual property position and operations.
In addition, there have been a significant number of recent consolidations
among pharmaceutical companies. Such consolidations among the companies with
which the Company is collaborating could result in the diminution or
termination of, or delays in, the development or commercialization of drug
candidates or research programs under one or more of the Collaborative
Agreements.
   
  Additional Financing Requirements; Uncertainty of Available Funding. The
Company will require substantial additional funds for its drug discovery and
development programs, for operating expenses, for pursuing regulatory
clearances, for the development of manufacturing, marketing and sales
capabilities and for prosecuting and defending its intellectual property
rights before it can expect to realize significant revenues from commercial
sales. The Company believes that the net proceeds of this Offering, together
with its existing capital resources, interest income and revenue from the
Collaborative Agreements, will be sufficient to fund its operating expenses
and capital requirements as currently planned through mid-1998. However, there
can be no assurance that such funds will be sufficient to fund its operating
expenses and capital requirements during such period. The Company's actual
cash requirements may vary materially from those now planned and will depend
upon numerous factors, including the results of the Company's research and
development and collaboration programs, the timing and results of pre-clinical
and clinical trials, the timing and costs of obtaining regulatory approvals,
the level of resources that the Company commits to the development of
manufacturing, marketing and sales capabilities, the ability of the Company to
maintain existing and establish new collaborative agreements with other
companies to provide funding to the Company, the technological advances and
activities of competitors and other factors. Thereafter, the Company will need
to raise substantial additional capital to fund its operations. The Company
intends to seek such additional funding through public or private financing or
collaborative or other arrangements with corporate partners. If additional
funds are raised by issuing equity securities, further dilution to existing
stockholders may result and future investors may be granted rights superior to
those of existing stockholders. There can be no assurance, however, that
additional financing will be available from any of these sources or, if
available, will be available on acceptable or affordable terms. If adequate
funds are not available, the Company may be required to delay, reduce the
scope of or eliminate one or more of its research and development programs or
to obtain funds by entering into arrangements with collaborative partners or
others that require the Company to issue additional equity securities or to
relinquish rights to certain technologies or drug candidates that the Company
would not otherwise issue or relinquish in order to continue independent
operations. See "Use of Proceeds" and "Management's Discussion and Analysis of
Financial Condition and Results of Operations."     
 
                                       7
<PAGE>
 
  History of Losses and Expectation of Future Losses; Uncertainty of Future
Profitability. The Company has incurred a cumulative operating loss of
approximately $14.0 million through June 30, 1996. Losses have resulted
principally from costs incurred in research and development activities related
to the Company's efforts to develop target candidates and from the associated
administrative costs. The Company expects to incur significant additional
operating losses over the next several years and expects cumulative losses to
increase substantially due to expanded research and development efforts, pre-
clinical and clinical trials and development of manufacturing, marketing and
sales capabilities. In the next few years, the Company's revenues may be
limited to research support payments under the Collaborative Agreements and
any amounts received under other research or drug development collaborations
that the Company has established or will establish. There can be no assurance,
however, that the Company will be able to establish any additional
collaborative relationships on terms acceptable to the Company or maintain in
effect the current Collaborative Agreements. The Company's ability to achieve
significant revenue or profitability is dependent on its or its collaborative
partners' ability to successfully complete the development of drug candidates,
to develop and obtain patent protection and regulatory approvals for the drug
candidates and to manufacture and commercialize the resulting drugs. The
Company will not receive revenues or royalties from commercial sales for a
significant number of years, if at all. Failure to receive significant
revenues or achieve profitable operations would impair the Company's ability
to sustain operations. There can be no assurance that the Company will ever
successfully identify, develop, commercialize, patent, manufacture and market
any products, obtain required regulatory approvals or achieve profitability.
See "Management's Discussion and Analysis of Financial Condition and Results
of Operations."
 
  Uncertainty of Patents and Proprietary Rights. The Company's success will
depend in part on its ability to obtain U.S. and foreign patent protection for
its drug candidates and processes, preserve its trade secrets and operate
without infringing the proprietary rights of third parties. Because of the
length of time and expense associated with bringing new drug candidates
through the development and regulatory approval process to the marketplace,
the pharmaceutical industry has traditionally placed considerable importance
on obtaining patent and trade secret protection for significant new
technologies, products and processes. There can be no assurance that any
additional patents will issue from any of the patent applications owned by, or
licensed to, the Company. Further, there can be no assurance that any rights
the Company may have under issued patents will provide the Company with
significant protection against competitive products or otherwise be
commercially viable. Legal standards relating to the validity of patents
covering pharmaceutical and biotechnological inventions and the scope of
claims made under such patents are still developing. There is no consistent
policy regarding the breadth of claims allowed in biotechnology patents. The
patent position of a biotechnology firm is highly uncertain and involves
complex legal and factual questions. There can be no assurance that any
existing or future patents issued to, or licensed by, the Company will not
subsequently be challenged, infringed upon, invalidated or circumvented by
others. In addition, patents may have been granted, or may be granted,
covering products or processes that are necessary or useful to the development
of the Company's drug candidates. If the Company's drug candidates or
processes are found to infringe upon the patents, or otherwise impermissibly
utilize the intellectual property of others, the Company's development,
manufacture and sale of such drug candidates could be severely restricted or
prohibited. In such event, the Company may be required to obtain licenses from
third parties to utilize the patents or proprietary rights of others. There
can be no assurance that the Company will be able to obtain such licenses on
acceptable terms, or at all. There has been significant litigation in the
industry regarding patents and other proprietary rights. If the Company
becomes involved in litigation regarding its intellectual property rights or
the intellectual property rights of others, the potential cost of such
litigation and the potential damages that the Company could be required to pay
could be substantial.
 
  In addition to patent protection, the Company relies on trade secrets,
proprietary know-how and technological advances which it seeks to protect, in
part, by confidentiality agreements with its collaborative partners, employees
and consultants. There can be no assurance that these confidentiality
agreements will not be breached, that the Company would have adequate remedies
for any such breach, or that the Company's trade secrets, proprietary know-how
and technological advances will not otherwise become known or be independently
discovered by others. See "Business--Patents and Proprietary Technology."
 
                                       8
<PAGE>
 
  Uncertainty Associated with Pre-clinical and Clinical Testing. Before
obtaining regulatory approvals for the commercial sale of any of the Company's
potential drugs, the drug candidates will be subject to extensive pre-clinical
and clinical trials to demonstrate their safety and efficacy in humans. The
Company is dependent on its collaborative partners to conduct clinical trials
for the drug candidates resulting from the Collaborative Agreements and may
become dependent on other third parties to conduct future clinical trials of
its internally developed drug candidates. The Company has no experience in
conducting pre-clinical or clinical trials, and no pre-clinical or clinical
trials have been commenced with respect to any of the Company's potential drug
candidates or any drug candidate being developed jointly by the Company and
its collaborative partners. Furthermore, there can be no assurance that pre-
clinical or clinical trials of any future drug candidates will demonstrate the
safety and efficacy of such drug candidates at all or to the extent necessary
to obtain regulatory approvals. Companies in the biotechnology industry have
suffered significant setbacks in advanced clinical trials, even after
demonstrating promising results in earlier trials. The failure to adequately
demonstrate the safety and efficacy of a drug candidate under development
could delay or prevent regulatory approval of the drug candidate and would
have a material adverse effect on the Company's business, operating results
and financial condition. See "Business--Government Regulation."
 
  No Assurance of Market Acceptance. There can be no assurance that any drugs
successfully developed by the Company, independently or with its collaborative
partners, if approved for marketing, will achieve market acceptance. The
antiinfective drugs which the Company is attempting to develop will compete
with a number of well-established antiinfective drugs manufactured and
marketed by major pharmaceutical companies. The degree of market acceptance of
any drugs developed by the Company will depend on a number of factors,
including the establishment and demonstration of the clinical efficacy and
safety of the Company's drug candidates, their potential advantage over
existing therapies and reimbursement policies of government and third-party
payors. There is no assurance that physicians, patients or the medical
community in general will accept and utilize any drugs that may be developed
by the Company independently or with its collaborative partners.
 
  Intense Competition. The biotechnology and pharmaceutical industries are
intensely competitive and subject to rapid and significant technological
change. Competitors of the Company in the United States and elsewhere are
numerous and include, among others, major, multinational pharmaceutical and
chemical companies, specialized biotechnology firms and universities and other
research institutions. Many of these competitors employ greater financial and
other resources, including larger research and development staffs and more
effective marketing and manufacturing organizations, than the Company or its
collaborative partners. Acquisitions of competing companies and potential
competitors by large pharmaceutical companies or others could enhance
financial, marketing and other resources available to such competitors. As a
result of academic and government institutions becoming increasingly aware of
the commercial value of their research findings, such institutions are more
likely to enter into exclusive licensing agreements with commercial
enterprises, including competitors of the Company, to market commercial
products. There can be no assurance that the Company's competitors will not
succeed in developing technologies and drugs that are more effective or less
costly than any which are being developed by the Company or which would render
the Company's technology and future drugs obsolete and noncompetitive.
 
  In addition, some of the Company's competitors have greater experience than
the Company in conducting pre-clinical and clinical trials and obtaining U.S.
Food and Drug Administration ("FDA") and other regulatory approvals.
Accordingly, the Company's competitors may succeed in obtaining FDA or other
regulatory approvals for drug candidates more rapidly than the Company.
Companies that complete clinical trials, obtain required regulatory agency
approvals and commence commercial sale of their drugs before their competitors
may achieve a significant competitive advantage, including certain patent and
FDA marketing exclusivity rights that would delay the Company's ability to
market certain products. There can be no assurance that drugs resulting from
the Company's research and development efforts, or from the joint efforts of
the Company and its collaborative partners, will be able to compete
successfully with competitors' existing products or products under development
or that they will obtain regulatory approval in the United States or
elsewhere.
 
                                       9
<PAGE>
 
  Impact of Extensive Government Regulation. The FDA and comparable agencies
in foreign countries impose substantial requirements upon the introduction of
pharmaceutical products through lengthy and detailed pre-clinical, laboratory
and clinical testing procedures, sampling activities and other costly and
time-consuming procedures to establish their safety and efficacy. All of the
Company's drug candidates will require governmental approvals for
commercialization, none of which have been obtained. Pre-clinical and clinical
trials and manufacturing of the Company's drug candidates will be subject to
the rigorous testing and approval processes of the FDA and corresponding
foreign regulatory authorities. Satisfaction of these requirements typically
takes a significant number of years and can vary substantially based upon the
type, complexity and novelty of the product. There can be no assurance as to
when Cubist, independently or with its collaborative partners, might first
submit an IND for FDA or other regulatory review. Government regulation also
affects the manufacturing and marketing of pharmaceutical products. See
"Business--The Cubist Programs."
 
  The effect of government regulation may be to delay marketing of the
Company's potential drugs for a considerable or indefinite period of time,
impose costly procedural requirements upon the Company's activities and
furnish a competitive advantage to larger companies or companies more
experienced in regulatory affairs. Delays in obtaining governmental regulatory
approval could adversely affect the Company's marketing as well as the
Company's ability to generate significant revenues from commercial sales.
There can be no assurance that FDA or other regulatory approvals for any drug
candidates developed by the Company will be granted on a timely basis or at
all. Moreover, if regulatory approval of a drug candidate is granted, such
approval may impose limitations on the indicated use for which such drug may
be marketed. Even if initial regulatory approvals for the Company's drug
candidates are obtained, the Company, its drugs and its manufacturing
facilities would be subject to continual review and periodic inspection, and
later discovery of previously unknown problems with a drug, manufacturer or
facility may result in restrictions on such drug or manufacturer, including
withdrawal of the drug from the market. The regulatory standards are applied
stringently by the FDA and other regulatory authorities and failure to comply
can, among other things, result in fines, denial or withdrawal of regulatory
approvals, product recalls or seizures, operating restrictions and criminal
prosecution.
 
  The FDA has developed two "fast track" policies for certain new drugs
(including antibiotics), one policy for expedited development and review and
one policy for accelerated approval. The expedited development and review
policy applies to new drug therapies that are intended to treat persons with
life-threatening and severely-debilitating illnesses, especially where no
satisfactory alternative therapy exists. The accelerated approval policy
applies to certain new drugs that are intended to treat persons with serious
or life-threatening illnesses that provide a meaningful therapeutic benefit to
patients over existing treatments. See "Business--Government Regulation."
There can be no assurance that any drug candidate contemplated by the Company
will qualify for the FDA's various fast track or priority approval policies.
Nor can there be any assurance that such policies will remain as currently
implemented by the FDA.
 
  As with many biotechnology and pharmaceutical companies, the Company is
subject to numerous environmental and safety laws and regulations. Any
violation of, and the cost of compliance with, these regulations could
materially adversely affect the Company's business, operating results and
financial condition. The Company is subject to periodic inspections and has
not received notice of any material violations of any environmental or safety
law or regulation. See "Business--Government Regulation."
 
  Dependence on Key Personnel. The Company is highly dependent upon the
efforts of its senior management and scientific team, including its President
and Chief Executive Officer. Although Dr. Rocklage has entered into an
employment agreement with the Company, the terms of the employment agreement
provide that Dr. Rocklage may terminate his employment with the Company at any
time upon thirty days' written notice. None of the Company's other executive
officers or key employees has entered into an employment agreement with the
Company. The loss of the services of one or more of these individuals might
impede the achievement of the Company's development objectives. Because of the
specialized scientific
 
                                      10
<PAGE>
 
nature of the Company's business, the Company is highly dependent upon its
ability to attract and retain qualified scientific and technical personnel.
There is intense competition among major pharmaceutical and chemical
companies, specialized biotechnology firms and universities and other research
institutions for qualified personnel in the areas of the Company's activities.
There can be no assurance that the Company will be able to continue to attract
and retain the qualified personnel necessary for the development of its
business. Loss of the services of, or failure to recruit, key scientific and
technical personnel could adversely affect the Company's business, operating
results and financial condition. See "Business--Employees" and "Management--
Executive Officers, Key Employees and Directors."
 
  Lack of Manufacturing, Marketing and Sales Capability and Experience. Cubist
has not yet invested in the development of manufacturing, marketing or sales
capabilities. The Company has no experience in, and currently lacks the
facilities and personnel to, manufacture products in accordance with Good
Manufacturing Practices ("GMP") as prescribed by the FDA or to produce an
adequate supply of compounds to meet future requirements for clinical trials.
If the Company is unable to develop or contract for manufacturing capabilities
on acceptable terms, the Company's ability to conduct pre-clinical and
clinical trials with the Company's drug candidates, if any, will be adversely
affected, resulting in delays in the submission of drug candidates for
regulatory approvals and in the initiation of new development programs, which
in turn could materially impair Cubist's competitive position and the
possibility of achieving profitability.
 
  The Company has no experience in marketing drugs. The Company has granted
marketing rights to its collaborative partners with respect to drugs developed
through the Collaborative Agreements. The Company may seek to collaborate with
a third party to market those drugs for which it has retained marketing rights
or may seek to market and sell such drugs directly. If the Company seeks to
collaborate with a third party, there can be no assurance that a collaborative
agreement can be reached on acceptable terms. If the Company seeks to market
and sell such drugs directly, the Company will need to hire additional
personnel skilled in marketing and sales as it develops drugs with commercial
potential. There can be no assurance that the Company will be able to acquire,
or establish third-party relationships to provide, any or all of these
capabilities.
 
  Reimbursement and Drug Pricing Uncertainty. The successful commercialization
of, and the interest of potential collaborative partners to invest in, the
development of the Company's drug candidates will depend substantially on
reimbursement of the costs of the resulting drugs and related treatments at
acceptable levels from government authorities, private health insurers and
other organizations, such as health maintenance organizations ("HMOs"). There
can be no assurance that reimbursement in the United States or elsewhere will
be available for any drugs the Company may develop or, if available, will not
be decreased in the future, or that reimbursement amounts will not reduce the
demand for, or the price of, the Company's drugs, thereby adversely affecting
the Company's business. If reimbursement is not available or is available only
to limited levels, there can be no assurance that the Company will be able to
obtain collaborative partners to manufacture and commercialize its drugs, or
would be able to obtain a sufficient financial return on its own manufacture
and commercialization of any future drugs.
 
  Third-party payors are increasingly challenging the prices charged for
medical products and services. Also, the trend toward managed health care in
the United States and the concurrent growth of organizations such as HMOs,
which can control or significantly influence the purchase of health care
services and products, as well as legislative proposals to reform health care
or reduce government insurance programs, may result in lower prices for
pharmaceutical products. The cost containment measures that health care
providers are instituting, including practice protocols and guidelines and
clinical pathways, and the effect of any health care reform, could materially
adversely affect the Company's ability to sell any of its drugs if
successfully developed and approved. Moreover, the Company is unable to
predict what additional legislation or regulation, if any, relating to the
health care industry or third-party coverage and reimbursement may be enacted
in the future or what effect such legislation or regulation would have on the
Company's business.
 
                                      11
<PAGE>
 
  Potential Product Liability and Availability of Insurance. The Company's
business exposes it to potential liability risks that are inherent in the
testing, manufacturing and marketing of pharmaceutical products. The use of the
Company's drug candidates in clinical trials may expose the Company to product
liability claims and possible adverse publicity. These risks will expand with
respect to the Company's drug candidates, if any, that receive regulatory
approval for commercial sale. Product liability insurance for the biotechnology
industry is generally expensive, if available at all. The Company does not have
product liability insurance but intends to obtain such coverage if and when its
drug candidates are tested in clinical trials. However, such coverage is
becoming increasingly expensive and there can be no assurance that the Company
will be able to obtain insurance coverage at acceptable costs or in a
sufficient amount, if at all, or that a product liability claim would not
adversely affect the Company's business, operating results or financial
condition.
   
  Control by Existing Stockholders. Upon completion of this Offering, the
Company's officers, directors and principal stockholders and their affiliates
will own or control approximately 71% of the Company's outstanding Common
Stock. As a result, these stockholders, acting together, will have the ability
to control most matters requiring approval by the stockholders of the Company,
including the election of the Company's Board of Directors.     
 
  No Prior Public Market; Stock Price Volatility. Prior to this Offering there
has been no public market for any of the Company's securities. Accordingly,
there can be no assurance that an active trading market will develop after this
Offering or that the Common Stock offered hereby will not decline below the
initial public offering price. The initial public offering price will be
determined by negotiations between the Company and the Representatives. See
"Underwriting." The market price of the Company's securities is likely to be
highly volatile. Factors such as announcements of technological innovations,
new commercial products, preclinical and clinical trials by the Company or its
competitors, other evidence of the safety or efficacy of products of the
Company or its competitors, governmental regulations and developments, health
care legislation, developments relating to patents or proprietary rights of the
Company or its competitors, including litigation, fluctuations in the Company's
operating results, market conditions for biotechnology stocks in general and
other factors may have a significant effect on the market price of the
Company's Common Stock. There has also been a history of significant volatility
in the market price for shares of other companies in the biotechnology field.
   
  Possible Adverse Impact of Shares Available for Future Sale.  Sales of
substantial amounts of Common Stock (including shares issued upon the exercise
of outstanding options and warrants) in the public market after this Offering
or the prospect of such sales could adversely affect the market price of the
Common Stock and may have a material adverse effect on the Company's ability to
raise any necessary capital to fund its future operations. Upon completion of
this Offering, the Company will have 8,373,023 shares of Common Stock
outstanding. The 2,000,000 shares offered hereby will be freely tradeable
without restriction or further registration under the Securities Act of 1933,
as amended (the "Securities Act"), except for any shares held by "affiliates"
of the Company within the meaning of the Securities Act which will be subject
to the resale limitations of Rule 144 promulgated under the Securities Act
("Rule 144"). The remaining 6,373,023 shares are "restricted" securities that
may be sold only if registered under the Securities Act, or sold in accordance
with an applicable exemption from registration, such as Rule 144. The officers,
directors, employees and other stockholders, who together hold 6,373,023 shares
of Common Stock, and options to purchase an additional 520,660 shares of Common
Stock, have agreed not to sell directly or indirectly, any Common Stock without
the prior written consent of UBS Securities LLC for a period of 180 days from
the date of this Prospectus (the "Lock-up Agreements"). Commencing on the
expiration of the Lock-up Agreements, 3,825,164 shares of Common Stock will be
eligible for sale in the public market, subject to compliance with Rule 144. In
addition, holders of 5,453,488 shares of Common Stock will be entitled to
certain registration rights with respect to such shares. If such holders, by
exercising their registration rights, cause a large number of shares to be
registered and sold in the public market, such sales could have a material
adverse effect on the market price of the Common Stock. In addition, any demand
of such holders to include such shares in Company-initiated registration
statements could have an adverse effect on the Company's ability to raise
needed capital. See "Description of Capital Stock--Registration Rights" and
"Shares Eligible for Future Sale."     
 
                                       12
<PAGE>
 
  Potential Anti-Takeover Effect of Certain Charter and By-Law
Provisions. Pursuant to the Company's Restated Certificate of Incorporation,
to be effective upon the closing of this Offering (the "Restated Certificate
of Incorporation"), special meetings of stockholders may be called only by the
Chairman of the Board, the President or a majority of the Board of Directors
of the Company. In addition, the Restated Certificate of Incorporation
authorizes the Board of Directors to issue preferred stock and to determine
its rights and preferences in order to eliminate delays associated with a
stockholder vote on specific issuances. The Company has no present plans to
issue any shares of preferred stock. The Restated Certificate of Incorporation
also provides for staggered elections of the Company's Board of Directors and
specific procedures for director nominations by stockholders and submission of
other proposals for consideration at stockholder meetings. These provisions
may have the effect of deterring hostile takeovers or delaying or preventing
changes in control or management of the Company, including transactions in
which stockholders might otherwise receive a premium for their shares over
then-current market prices. Certain provisions of Delaware law applicable to
the Company could also delay or make more difficult a merger, tender offer or
proxy contest involving the Company, including Section 203 of the Delaware
General Corporation Law (the "DGCL"), which prohibits a Delaware corporation
from engaging in any business combination with any stockholder owning 15% or
more of Company's outstanding voting stock ("interested stockholder") for a
period of three years from the date a stockholder becomes an interested
stockholder unless certain conditions are met. These provisions could also
limit the price that investors might be willing to pay in the future for
shares of Common Stock. See "Description of Capital Stock--Delaware Law and
Certain Charter and By-Law Provisions."
   
  Dilution. The initial public offering price is substantially higher than the
net tangible book value per share of the currently outstanding Common Stock.
Investors purchasing shares of Common Stock in this Offering will therefore
suffer immediate dilution in net tangible book value of $7.82 per share. The
dilution will be increased to the extent that the holders of outstanding
options or warrants to purchase Common Stock at prices below the initial
public offering price exercise such options or warrants. See "Dilution."     
 
  Absence of Dividends. The Company has never declared or paid cash dividends
and does not intend to declare or pay any cash dividends in the foreseeable
future. See "Dividend Policy."
 
                                      13
<PAGE>
 
                                USE OF PROCEEDS
   
  The net proceeds to the Company from the sale of the shares of Common Stock
offered by the Company hereby are estimated to be approximately $19,860,000
($22,929,000 if the Underwriters' over-allotment option is exercised in full),
based on an assumed initial public offering price of $11.00 per share and after
deducting the estimated underwriting discounts and commissions and estimated
offering expenses payable by the Company.     
 
  The Company intends to use the net proceeds for research and development,
working capital and general corporate purposes. The Company may also use a
portion of the net proceeds to acquire or license products or technologies
complementary to the Company's business, although the Company has no agreements
or commitments for any such acquisition or license. Pending such use, the
Company intends to invest the net proceeds in interest-bearing, investment-
grade securities.
   
  The Company believes that the net proceeds of this Offering, together with
its existing capital resources, interest income and revenue from the
Collaborative Agreements, will be sufficient to fund its operating expenses and
capital requirements as currently planned through mid-1998. However, there can
be no assurance that such funds will be sufficient to fund its operating
expenses and capital requirements during such period. The Company's actual cash
requirements may vary materially from those now planned and will depend upon
numerous factors, including the results of the Company's research and
development and collaboration programs, the timing and results of pre-clinical
and clinical trials, the timing and costs of obtaining regulatory approvals,
the level of resources that the Company commits to the development of
manufacturing, marketing and sales capabilities, the ability of the Company to
maintain existing and establish new collaborative arrangements with other
companies to provide funding to the Company, the technological advances and
activities of competitors, and other factors. See "Risk Factors--Additional
Financing Requirements; Uncertainty of Available Funding."     
 
 
                                DIVIDEND POLICY
 
  The Company has not declared or paid any cash dividends on its capital stock
since its inception and does not anticipate paying cash dividends in the
foreseeable future.
 
                                       14
<PAGE>
 
                                 CAPITALIZATION
   
  The following table sets forth at June 30, 1996 (i) the actual capitalization
of the Company, (ii) the pro forma capitalization of the Company, as described
in Note 1 below, and (iii) the pro forma capitalization of the Company as
adjusted to reflect the receipt of the estimated proceeds from the sale of
2,000,000 shares of Common Stock being offered by the Company hereby after
deducting the estimated underwriting discounts and commissions and estimated
offering expenses payable by the Company. This table should be read in
conjunction with the Financial Statements of the Company and Notes thereto
included elsewhere in this Prospectus.     
 
<TABLE>   
<CAPTION>
                                                    JUNE 30, 1996
                                      ------------------------------------------
                                                                   PRO FORMA
                                       ACTUAL    PRO FORMA(1)  AS ADJUSTED(1)(2)
                                      --------  -------------- -----------------
                                                (in thousands)
<S>                                   <C>       <C>            <C>
Long-term debt and capital lease ob-
 ligations, less current portion....  $  1,206     $  1,206        $  1,206
Stockholders' equity:
  Preferred Stock, par value $.001
   per share; 43,000,000 shares
   authorized and 37,568,085 shares
   issued and outstanding, actual;
   5,000,000 shares authorized and
   no shares issued and outstanding,
   pro forma and pro forma as
   adjusted.........................        38          --              --
  Common Stock, par value $.001 per
   share; 52,000,000 shares
   authorized and 1,006,154 shares
   issued and outstanding, actual;
   25,000,000 shares authorized, pro
   forma and pro forma as adjusted;
   6,373,023 issued and outstanding,
   pro forma and 8,373,023 shares
   issued and outstanding, pro forma
   as adjusted(3)...................         1            6               8
  Additional paid-in capital........    20,756       20,789          40,647
  Accumulated deficit...............   (14,005)     (14,005)        (14,005)
                                      --------     --------        --------
   Total stockholders' equity.......     6,790        6,790          26,650
                                      --------     --------        --------
   Total capitalization.............  $  7,996     $  7,996        $ 27,856
                                      ========     ========        ========
</TABLE>    
- --------
(1) Presented on a pro forma basis to give effect to (i) the conversion upon
    the closing of this Offering of all outstanding shares of the Company's
    Preferred Stock into an aggregate of 5,366,869 shares of Common Stock and
    (ii) the amendment of the Company's Restated Certificate of Incorporation
    prior to the date of this Prospectus.
   
(2) Adjusted to reflect the sale of 2,000,000 shares of Common Stock offered
    hereby and receipt by the Company of the estimated net proceeds therefrom,
    based upon an assumed initial public offering price of $11.00 per share and
    after deducting the underwriting discount and estimated offering expenses
    payable by the Company. See "Use of Proceeds."     
   
(3) Excludes (i) an aggregate of 520,660 shares of Common Stock issuable
    pursuant to stock options outstanding as of June 30, 1996, at a weighted
    average exercise price per share of $1.37, (ii) 86,619 shares of Common
    Stock issuable pursuant to warrants outstanding as of June 30, 1996, at a
    weighted average exercise price per share of $4.04, and (iii) Common Stock
    that may be issued after the closing of this Offering to Bristol-Myers
    Squibb pursuant to certain antidilution rights of Bristol-Myers Squibb.
        
                                       15
<PAGE>
 
                                    DILUTION
   
  As of June 30, 1996, the Company had a net tangible book value of $6,790,000,
or $1.07 per share. Net tangible book value per share is determined by dividing
the net tangible book value (tangible assets less liabilities) of the Company
by 6,373,023 shares of Common Stock outstanding at such date, after giving
effect to the conversion upon the closing of this Offering of all outstanding
shares of the Company's Preferred Stock into an aggregate of 5,366,869 shares
of Common Stock. Net tangible book value dilution per share represents the
difference between the amount per share paid by purchasers of Common Stock in
this Offering and the net tangible book value per share of Common Stock
immediately after the completion of this Offering. Without taking into account
any changes in net tangible book value after June 30, 1996 other than as
described above and to give effect to the sale by the Company of the 2,000,000
shares of Common Stock offered hereby and the receipt by the Company of the
estimated net proceeds therefrom, the pro forma net tangible book value of the
Company as of June 30, 1996 would have been $3.18 per share. This represents an
immediate increase in the pro forma net tangible book value of $2.11 per share
to existing investors and an immediate dilution in net tangible book value of
$7.82 per share to new investors purchasing shares of Common Stock in this
Offering.     
 
  The following table illustrates this per share dilution:
 
<TABLE>     
   <S>                                                            <C>   <C>
     Assumed initial public offering price per share.............       $11.00
     Pro forma net tangible book value per share as of June 30,
      1996....................................................... $1.07
     Increase per share attributable to this Offering............  2.11
                                                                  -----
     Pro forma net tangible book value per share after this
      Offering...................................................         3.18
                                                                        ------
     Dilution per share to new investors.........................       $ 7.82
                                                                        ======
</TABLE>    
 
  The following table summarizes as of June 30, 1996, the total number of
shares of Common Stock purchased from the Company (adjusted to give effect to
the automatic conversion of all outstanding shares of Preferred Stock into
5,366,869 shares of Common Stock upon the closing of this Offering), the total
consideration paid, and the average price per share paid by existing
stockholders and by new investors:
 
<TABLE>   
<CAPTION>
                                 SHARES PURCHASED  TOTAL CONSIDERATION  AVERAGE
                                 ----------------- -------------------   PRICE
                                  NUMBER   PERCENT   AMOUNT    PERCENT PER SHARE
                                 --------- ------- ----------- ------- ---------
<S>                              <C>       <C>     <C>         <C>     <C>
Existing stockholders........... 6,373,023   76.1% $21,083,536   48.9%  $ 3.31
New investors................... 2,000,000   23.9   22,000,000   51.1    11.00
                                 ---------  -----  -----------  -----
    Total....................... 8,373,023  100.0% $43,083,536  100.0%
                                 =========  =====  ===========  =====
</TABLE>    
   
  The foregoing table assumes no exercise of outstanding options or warrants to
purchase Common Stock after June 30, 1996, and excludes Common Stock that may
be issued after the closing of this Offering to Bristol-Myers Squibb pursuant
to certain antidilution rights of Bristol-Myers Squibb. At June 30, 1996, there
were outstanding options granted under the Amended and Restated 1993 Stock
Option Plan (the "Plan"), exercisable for an aggregate of 520,660 shares of
Common Stock at a weighted average exercise price of $1.37 per share. In
addition, at June 30, 1996 there were outstanding warrants to purchase 86,619
shares of Common Stock at a weighted average exercise price per share of $4.04.
The exercise of these options and warrants and the issuance of Common Stock to
Bristol-Myers Squibb after the closing of this Offering would result in further
dilution to new investors. See "Management--Amended and Restated 1993 Stock
Option Plan," "Certain Transactions" and "Description of Capital Stock--
Warrants."     
 
                                       16
<PAGE>
 
                            SELECTED FINANCIAL DATA
 
  The following Selected Financial Data should be read in conjunction with the
Company's Financial Statements and the Notes thereto, "Management's Discussion
and Analysis of Financial Condition and Results of Operations" and other
financial information included elsewhere in this Prospectus. The data set forth
below, as of December 31, 1994 and 1995 and for each of the three years in the
period ended December 31, 1995, are derived from the Company's financial
statements which have been audited by Coopers & Lybrand L.L.P., independent
accountants, and which are included elsewhere in this Prospectus. The selected
financial data as of December 31, 1992 and 1993 and for the period from
inception (May 1, 1992) to December 31, 1992 are derived from and are qualified
by reference to, the Company's financial statements not included in this
Prospectus, all of which have been audited by Coopers & Lybrand L.L.P.,
independent accountants. The selected financial data at June 30, 1996 and for
the six months ended June 30, 1995 and 1996 are derived from the Company's
unaudited financial statements included elsewhere in this Prospectus and
include, in the opinion of the Company, all adjustments (consisting only of
normal recurring adjustments) necessary for a fair presentation of the
Company's financial position at that date and results of operations for those
periods. Operating results for the six months ended June 30, 1996 are not
necessarily indicative of the results for any future period.
 
<TABLE>   
<CAPTION>
                            PERIOD FROM
                             INCEPTION                                    SIX MONTHS
                           (MAY 1, 1992)   YEARS ENDED DECEMBER 31,     ENDED JUNE 30,
                          TO DECEMBER 31, ----------------------------  ----------------
                               1992         1993      1994      1995     1995     1996
                          --------------- --------  --------  --------  -------  -------
                                    (in thousands, except per share data)
<S>                       <C>             <C>       <C>       <C>       <C>      <C>
STATEMENTS OF OPERATIONS
 DATA:
Sponsored research
 revenues...............       $--        $    --   $    --   $  1,271  $   100  $ 2,047
Operating expenses......
 Research and
  development...........         32          1,169     3,309     4,965    2,595    3,183
 General and
  administrative........          6            547     1,449     1,708      819      873
                               ----       --------  --------  --------  -------  -------
 Total operating
  expenses..............         38          1,716     4,758     6,673    3,414    4,056
                               ----       --------  --------  --------  -------  -------
Interest income.........          3             45       113       239       90       43
Interest expense........        --             (17)     (168)     (233)    (100)    (107)
                               ----       --------  --------  --------  -------  -------
 Net loss...............       $(35)      $ (1,688) $ (4,813) $ (5,396) $(3,324) $(2,073)
                               ====       ========  ========  ========  =======  =======
Pro forma net loss per
 share(1)...............                                      $  (0.91)          $ (0.32)
                                                              ========           =======
Pro forma weighted
 average common and
 common equivalent
 shares outstanding(1)..                                         5,898             6,449
</TABLE>    
 
<TABLE>
<CAPTION>
                                        DECEMBER 31,
                                  --------------------------  JUNE 30,
                                   1993     1994      1995      1996
                                  -------  -------  --------  --------
                                             (in thousands)
<S>                               <C>      <C>      <C>       <C>       <C>
BALANCE SHEET DATA:
Cash, cash equivalents and
 investments....................  $ 4,457  $ 1,221  $  3,056  $  4,732
Working capital.................    3,937      (92)    3,215     5,023
Total assets....................    7,241    4,250     7,048    10,355
Long-term debt and capital lease
 obligations, less current
 portion........................    1,164    2,032     1,257     1,206
Accumulated deficit.............   (1,723)  (6,536)  (11,932)  (14,005)
Total stockholders' equity......    5,488      823     4,895     6,790
</TABLE>
- --------
(1) Computed on the basis described in Note B of the Notes to the Financial
    Statements.
 
                                       17
<PAGE>
 
  MANAGEMENT'S DISCUSSION AND ANALYSIS OF FINANCIAL CONDITION AND RESULTS OF
                                  OPERATIONS
 
  The following discussion of the financial condition and results of
operations of the Company should be read in conjunction with the Financial
Statements and the related Notes thereto included elsewhere in this
Prospectus. This Prospectus contains forward-looking statements which involve
risk and uncertainties. The Company's actual results may differ significantly
from the results discussed in the forward-looking statements. Factors that
might cause such a difference include, but are not limited to, those discussed
in "Risk Factors."
 
OVERVIEW
 
  Since its incorporation on May 1, 1992 and commencement of operations in
February 1993, Cubist has been engaged in the research, development and
commercialization of novel antiinfective drugs to treat infectious diseases
caused by bacteria and fungi, primarily those resistant to existing
antiinfective drugs. To date, the Company has raised over $23.0 million in
funding primarily through the sale of preferred stock. Additionally, the
Company has received several SBIR grants from the National Institutes of
Health. The Company has a limited history of operations and has experienced
significant operating losses since inception. The Company expects to incur
significant additional operating losses over the next several years and
expects cumulative losses to increase substantially due to expanded research
and development efforts, pre-clinical and clinical trials and development of
manufacturing, marketing and sales capabilities.
 
  A key element of the Company's strategy is to enhance certain of its drug
discovery and development programs and to fund its capital requirements, in
part, by entering into collaborative agreements with major pharmaceutical
companies. To date, the Company has entered into agreements based specifically
on the Synthetase Program with Bristol-Myers Squibb, Merck and Pfizer.
Assuming that the Collaborative Agreements continue until their scheduled
expirations, and that a separate drug is successfully developed and
commercialized from each of the five research programs to be conducted
pursuant to these agreements, Cubist will be entitled to receive a total of
$98.5 million in research support payments, technology licensing fees,
milestone payments and equity investments. In addition, the Company will be
entitled to receive royalties on worldwide sales of any drug developed and
commercialized from the collaborations.
 
RESULTS OF OPERATIONS
 
 Six Months Ended June 30, 1996 and 1995
 
  Revenues. Total revenues in the six months ended June 30, 1996, were
$2,046,653 compared to $100,000 in the six months ended June 30, 1995. The
Company received $16,666 relating to Bristol-Myers Squibb research funding,
$1,915,000 relating to Merck license fees and research funding, $37,000
relating to Pfizer research funding, and $77,987 relating to revenues from
SBIR grants. In the six months ended June 30, 1995, the Company recognized
$100,000 relating to revenues from SBIR grants.
 
  Research and Development Expenses. Total research and development expenses
were $3,182,609 in the six months ended June 30, 1996 compared to $2,594,884
in the six months ended June 30, 1995, an increase of $587,725 or 22.6%. The
increase was largely due to increased costs related to additional personnel,
laboratory research supplies and compound purchases to expand the Company's
compound collection.
 
  General and Administrative Expenses. General and administrative expenses
were $873,586 in the six months ended June 30, 1996 compared to $818,977 in
the six months ended June 30, 1995, an increase of $54,609 or 6.7%. The
increase is primarily due to increased legal expenses related to the three
collaborations in the six months ended June 30, 1996 as compared to the six
months ended June 30, 1995.
 
  Interest Income and Expense. Interest income was $43,232 in the six months
ended June 30, 1996, compared to $90,312 in the six months ended June 30,
1995, a decrease of $47,080 or 52.1%. The decrease is primarily due to a
decrease in the average cash balance in the six months ended June 30, 1996, as
compared to the six months ended June 30, 1995. Interest expense was $106,903
in the six months ended June 30, 1996 compared to $100,806 in the six months
ended June 30, 1995, an increase of $6,097 or 6.0%.
 
                                      18
<PAGE>
 
  Net Loss. The net loss was $2,073,213 during the six months ended June 30,
1996 and $3,324,355 during the six months ended June 30, 1995, a decrease of
$1,251,142 or 37.6% primarily as a result of the revenues and other items
discussed above.
 
 Years ended December 31, 1995 and 1994
 
  Revenues. Total revenues in 1995 were $1,271,333. No revenues were received
in 1994. The Company recognized $283,000 relating to three SBIR Phase I grants
awarded during 1995. In addition, sponsored research revenues were recognized
upon the signing of the Pfizer Agreement in December 1995. Revenues included
$500,000 in license fees and $488,000 in research funding.
 
  Research and Development Expenses. Total research and development expenses
were $4,964,876 in 1995 compared to $3,309,161 in 1994, an increase of
$1,655,715 or 50.0%. The increase was largely due to increased costs related
to additional personnel, increased facility-related expenses reflecting the
construction of 6,500 square feet of additional laboratory space and increased
license and collaboration expenses.
 
  General and Administrative Expenses. General and administrative expenses
were $1,708,513 in 1995 compared to $1,448,928 in 1994, an increase of
$259,585 or 17.9%. The increase is primarily due to increased compensation
expenses reflecting a full year of executive compensation and increased patent
application expenses offset by decreased relocation expenses.
 
  Interest Income and Expense. Interest income was $239,030 in 1995 compared
to $113,338 in 1994, an increase of $125,692 or 110.9%. This increase was due
to an increase in the average cash balance from two equity financings during
1995 raising approximately $9,000,000. Interest expense was $232,980 in 1995
compared to $168,284 in 1994, an increase of $64,696 or 38.4%. This increase
was due to additional capital lease obligations entered into during 1995.
 
  Net Loss. The net loss was $5,396,006 during 1995 and $4,813,035 during
1994, an increase of $582,971 or 12.1%. The increase was primarily due to
additional expenses incurred to support the advancement of the Company's
internal research programs. Offsetting these additional expenses were revenues
associated with the Pfizer Agreement and SBIR Phase I grants.
 
 Years ended December 31, 1994 and 1993
 
  Revenues. No revenues were received during these periods.
 
  Research and Development Expenses. Total research and development expenses
were $3,309,161 in 1994 compared to $1,169,168 in 1993, an increase of
$2,139,993 or 183.0%. The increase was largely due to increased costs related
to additional personnel, as well as increased laboratory research supplies
supporting the advancement of the Company's internal research programs.
 
  General and Administrative Expenses. General and administrative expenses
were $1,448,928 in 1994 compared to $546,843 in 1993, an increase of $902,085
or 165.0%. The increase is primarily due to increased compensation and
recruiting expenses and legal expenses associated with patent filings.
 
  Interest Income and Expense. Interest income was $113,338 in 1994 compared
to $45,028 in 1993, an increase of $68,310 or 151.7%. This increase was due to
an increase in the average cash balance due to an equity infusion during
August 1993 raising approximately $7,100,000. Interest expense was $168,284 in
1994 compared to $16,911 in 1993, an increase of $151,373 or 895.1%. This
increase was due to capital lease obligations entered into during 1994 and a
full year of interest expense incurred in 1994 for debt entered into by the
Company relating to the facility renovation in September 1993.
 
  Net Loss. The net loss was $4,813,035 during 1994 and $1,687,894 in 1993, an
increase of $3,125,141 or 185.2%. The increase was primarily due to additional
expenses incurred to support the advancement of the Company's internal
research programs.
 
                                      19
<PAGE>
 
LIQUIDITY AND CAPITAL RESOURCES
 
  Since inception, the Company has financed its operations through the sale of
equity securities, equipment financing, sponsored research revenues, license
revenues and interest earned on invested capital. The Company's total cash,
cash equivalent and investments balance at June 30, 1996 was $4,732,273
compared to $3,056,124 at December 31, 1995. The Company raised approximately
$8,468,000 in equity financings, $488,000 in sponsored research revenues,
$283,000 in SBIR grants and $500,000 in licensing revenues during 1995.
 
  Net cash used in operating activities was $6,514,231 in 1995 compared to
$3,753,728 and $1,390,476 in 1994 and 1993, respectively. The cash used in
operations was primarily to fund research and development and for general and
administrative expenses.
 
  The Company has entered into Collaborative Agreements with Bristol-Myers
Squibb, Merck and Pfizer. Assuming that the Collaborative Agreements continue
until their scheduled expirations, and that a separate drug is successfully
developed and commercialized from each of the five research programs to be
conducted pursuant to these agreements, Cubist will be entitled to receive a
total of $98.5 million in research support payments, technology licensing
fees, milestone payments and equity investments. In addition, the Company will
be entitled to receive royalties on worldwide sales of drugs resulting from
these collaborations. Through July 1996, the Company's collaborative partners
have provided the Company with $3.8 million of research support payments and a
technology licensing fee and $4.0 million in equity investments. There can be
no assurance that the Company will receive any additional funding from the
Collaborative Agreements. See "Risk Factors--Dependence on Collaborative
Partners and Others" and "Business--Collaborative Agreements."
 
  As of June 30, 1996, the Company had invested $4,171,086 in property and
equipment, primarily in facility renovations and laboratory equipment under
capital leases. The present value of obligations under capital leases at June
30, 1996 was $1,266,596. Minimum annual principal payments due under capital
leases total $520,060 in 1996 and 1997. Principal payments decline each year
thereafter until expiration in 1999. The Company made principal payments under
capital lease obligations in 1995 and 1994 of $318,272 and $212,428,
respectively. The Company expects its capital expenditures in 1996 to be
approximately $1,000,000, consisting of $300,000 in leasehold improvements and
$700,000 of laboratory and other equipment purchases.
   
  The Company believes that the net proceeds of this Offering, together with
its existing capital resources, interest income and revenue from the
Collaborative Agreements, will be sufficient to fund its operating expenses
and capital requirements as currently planned through mid-1998. These funding
requirements include continued expenditures for research and development
activities, as well as expenditures related to leasehold improvements and the
purchase of additional laboratory and other equipment. The Company has not
entered into any formal commitments to use the proceeds from the Offering for
increased personnel, capital expenditures or any other purpose. The Company's
actual cash requirements may vary materially from those now planned and will
depend upon numerous factors. There can be no assurance that the net proceeds
of this Offering, together with the Company's existing capital resources,
interest income and revenue from the Collaborative Agreements, will be
sufficient to fund the Company's operating expenses and capital requirements
during such period. Thereafter, the Company will need to raise substantial
additional capital to fund its operations. The Company intends to seek such
additional funding through public or private financing or collaborative or
other arrangements with corporate partners. See "Use of Proceeds" and "Risk
Factors--Additional Financing Requirements; Uncertainty of Available Funding."
    
RECENT ACCOUNTING PRONOUNCEMENTS
 
  In March 1995, the Financial Accounting Standards Board ("FASB") issued SFAS
No. 121, "Accounting for the Impairment of Long-Lived Assets and for Long-
Lived Assets to be Disposed Of." This standard is effective for financial
statements for fiscal years beginning after December 15, 1995. The Company's
analysis of this new standard indicates that it will not have a material
effect on the Company's financial position or results of operations.
 
                                      20
<PAGE>
 
  In October 1995, the FASB issued SFAS No. 123, "Accounting for Stock-Based
Compensation," which encourages companies to recognize compensation expense in
the income statement based on the fair value of the underlying common stock at
the date of the awards are granted. However, it will permit continued
accounting under APB Opinion 25, "Accounting for Stock Issued to Employees,"
accompanied by a disclosure of the pro forma effects on net income and
earnings per share had the new accounting rules been applied. The statement is
effective for fiscal year 1996. The Company has determined that it will elect
the disclosure-only alternative permitted under SFAS No. 123. The Company will
be required to disclose pro forma net income and pro forma earnings per share
in the footnotes using the fair value based method beginning in 1996 with
comparable disclosures for 1995. The Company has not determined the impact of
the pro forma adjustments to its net income or earnings per share.
 
                                      21
<PAGE>
 
                                   BUSINESS
 
THE COMPANY
 
  Cubist Pharmaceuticals, Inc. ("Cubist" or the "Company") is a
biopharmaceutical company engaged in the research, development and
commercialization of novel antiinfective drugs to treat infectious diseases
caused by bacteria and fungi, primarily those resistant to existing
antiinfective drugs. The increasing prevalence of drug-resistant bacterial and
fungal pathogens has led to significantly higher mortality rates from
infectious diseases and currently presents a serious crisis worldwide.
Cubist's strategy for combating antiinfective drug resistance is to identify
novel intracellular targets essential for cell function in bacteria and fungi,
such as proteins, RNA or DNA, which if inhibited by a drug would kill or
attenuate the growth of the pathogen. Cubist selects these targets based on a
thorough understanding of their function, thereby providing a foundation for
assay development and identification of leads for drug discovery.
 
  Cubist believes that its rational, target-based, drug discovery strategy
represents a distinct departure from and offers significant advantages over
traditional drug discovery strategies to counter drug resistance. These
traditional strategies have generally involved (i) whole-cell screening
methodologies which provide only limited knowledge of target function, (ii)
chemical modifications of existing antiinfective drugs, such as penicillin, or
(iii) the combination of existing antiinfective drugs with an antibiotic
potentiator to block drug resistance. For decades, antiinfective drug
discovery research has utilized only a fixed number of targets and chemical
structures thereby limiting the ability of these approaches to identify new
classes of drugs effective against drug-resistant bacteria and fungi. Cubist
believes that the identification of new drug classes inhibiting new targets
will provide a compelling solution to drug resistance. The Company has
identified over 100 proprietary targets and related assays for the discovery
of new drugs. The Company expects that drugs inhibiting these new targets will
be immediately effective against drug-resistant bacteria and fungi since these
pathogens have not had an opportunity to evolve resistance specific to these
new drugs. Furthermore, Cubist's most advanced drug discovery program could
identify a drug which inhibits more than one essential target for a given
pathogen, which would significantly decrease the rate of emergence of drug
resistance.
 
  Cubist's initial focus is on the identification and development of
antiinfective drugs to inhibit selected targets involved in the essential
process of protein synthesis. Cubist's programs are based on targets that are
responsible for the: (i) addition or charging of amino acids to tRNA molecules
by enzymes known as aminoacyl-tRNA synthetases, (ii) cleavage by the enzyme
ribonuclease P of immature tRNA to form mature tRNA prior to its charging with
amino acids by the enzyme ribonuclease P, (iii) modification of the amino acid
glutamate into glutamine on incorrectly charged tRNAs by the enzyme
amidotransferase and (iv) transport of amino acid-charged tRNA molecules to
the site of protein synthesis by elongation factors. The Company believes that
its target-based programs will enable the development of clinically effective
drugs to treat infectious diseases caused by pathogens such as staphylococci,
enterococci, streptococci and candida. To date, the Company has identified
lead candidates targeting certain aminoacyl-tRNA synthetases, which
demonstrate potency and selectivity and inhibit the growth of bacteria or
fungi. Cubist expects to complete optimization of these lead candidates and
select its first drug candidate for pre-clinical development by the end of
1996. Assuming successful pre-clinical development, the Company expects to
file an IND application by the end of 1997.
 
  A key element of the Company's strategy is to enter into collaborations with
major pharmaceutical companies to develop its initial products. These
collaborations are expected to provide the Company with funding, research and
development resources, and access to libraries of diverse compounds and
clinical development, manufacturing and commercialization capabilities. To
date, the Company has entered into collaborative agreements based on certain
targets within the Synthetase Program with Bristol-Myers Squibb, Merck and
Pfizer to screen the collaborators' respective compound libraries against
certain aminoacyl-tRNA synthetase targets. Assuming that the Collaborative
Agreements continue until their scheduled expirations, and that a separate
drug is successfully developed and commercialized from each of the five
research programs
 
                                      22
<PAGE>
 
   
to be conducted pursuant to these agreements, Cubist will be entitled to
receive a total of $98.5 million in research support payments, technology
licensing fees, milestone payments and equity investments. In addition, the
Company will be entitled to receive royalties on worldwide sales of drugs
resulting from these collaborations. Through July 1996, the Company's
collaborative partners have provided the Company with $3.8 million of research
support payments and a technology licensing fee and $4.0 million in equity
investments.     
 
  Apart from these collaborations, Cubist has retained rights to internally
develop and commercialize certain proprietary products which will enable the
Company either to commercialize certain drug candidates independently or to
enter into future drug development and commercialization alliances with third
parties at a later stage in the development process.
 
OVERVIEW OF INFECTIOUS DISEASE AND DRUG RESISTANCE
 
  Infectious diseases are caused by bacteria and fungi present in the
environment that enter the body through the skin or mucous membranes of the
lungs, nasal passages and gastrointestinal tract, and overwhelm the body's
immune system. These pathogens then establish themselves in various tissues
and organs throughout the body and cause a number of serious and, in some
cases, lethal infections, including those of the bloodstream, heart, lung,
liver and urinary tract.
 
  The increasing prevalence of and rise in mortality rates from infectious
diseases places additional stress on the already overburdened U.S. health care
system. According to estimates from the CDC, approximately two million
hospital-acquired infections occur each year, causing more than eight million
days of extended hospital stay and resulting in more than $4.5 billion in
additional health care costs each year. Based on CDC estimates, infectious
diseases ranked as the third leading cause of death in 1992, with mortality
rates increasing by 58% during the period from 1980 to 1992, in contrast to
mortality rates due to all causes which decreased by 3% during this period, as
shown in the following table:
 
           LEADING CAUSES OF MORTALITY BY INFECTIOUS DISEASE (U.S.)
 
<TABLE>
<CAPTION>
                                                NO. OF    MORTALITY
                                               DEATHS IN PER 100,000 % INCREASE
   INFECTIOUS DISEASE                            1992      IN 1992   1980-1992
   -------------------                         --------- ----------- ----------
   <S>                                         <C>       <C>         <C>
   Respiratory tract..........................    77,336     30.3         21 %
   HIV/AIDS(1)................................    33,581     13.2        N/A (2)
   Bloodstream................................    19,667      7.7         83
   Kidney/Urinary tract.......................    12,399      4.9         40
   Heart......................................     3,950      1.5         36
   Gall bladder...............................     2,494      1.0        100
   Fungal.....................................     2,298      0.9        200
   Other......................................    14,322      5.5        N/A (2)
                                               ---------    -----       ----
   All infectious diseases....................   166,047     65.0         58 %
   All deaths................................. 2,175,613    852.0         (3)%
</TABLE>
 
  --------
  (1) Although the HIV virus is known to be the underlying cause of AIDS, the
      majority of patients infected with AIDS die of opportunistic bacterial
      or fungal infections such as pneumonia.
  (2) N/A--data not available.
  Source: Journal of the American Medical Association estimates (1996).
 
                                      23
<PAGE>
 
  Antiinfective drugs have, in many cases, proven highly successful in
controlling the serious morbidity and mortality that accompany these
infections. These drugs work by chemically binding to specific targets in a
bacterial or fungal pathogen, thereby inhibiting a cell function essential to
its survival. Currently available antiinfective drugs can be divided into the
following four broad categories, according to the type of essential cell
function they inhibit: (i) protein synthesis (e.g., tetracyclines, macrolides
and aminoglycosides), (ii) cell wall and membrane synthesis (e.g., penicillins,
cephalosporins, carbapenems, glycopeptides and polyenes), (iii) nucleic acid
synthesis (e.g., fluoroquinolones) and (iv) cell metabolism (e.g.,
trimethoprim, sulfonamides, azoles and allylamines).
 
  Recently, there has been a rise in the incidence of infectious diseases
caused by bacteria and fungi that have developed resistance to existing
antiinfective drugs. This phenomenon has been well documented in medical
literature. A number of serious pathogens such as Staphylococcus aureus,
Streptococcus pneumoniae, Enterococcus faecalis, Enterococcus faecium,
Escherichia coli, Haemophilus influenzae, Pseudomonas aeruginosa, Mycobacterium
tuberculosis, Candida albicans, Aspergillus fumigatus and Aspergillus flavus
have shown significant evidence of drug resistance. The figure below shows the
increase in the incidence of hospital-acquired infections caused by drug-
resistant strains of Staphylococcus aureus and enterococci bacteria as
documented by the CDC, indicating significant and increasing levels of drug
resistance prevalent in these common, often lethal, pathogens.
 
 
 
       [LINE AND BAR CHARTS INDICATING INCIDENCE OF DRUG RESISTANCE IN  
                         HOSPITAL-ACQUIRED INFECTIONS]
 
 
  The increasing prevalence of drug-resistant pathogens has contributed to
higher mortality rates from infectious diseases, particularly those caused by
Staphylococcus aureus and Streptococcus pneumoniae. Staphylococcus aureus is
the most common pathogen to cause blood-borne infections and the most
frequently isolated pathogen in skin and soft tissue infections. Recent data
show that methicillin-resistant strains of Staphylococcus aureus have been
found in approximately 24% of the patient population in U.S. nursing homes.
During the years 1990 to 1993, the mortality rate for individuals with blood-
borne methicillin-resistant Staphylococcus aureus was 42%, as compared to 22%
for individuals infected with methicillin-susceptible strains. Streptoccocus
pneumoniae is the most frequently isolated pathogen in children with otitis
media (middle ear infections) and in adults with sinusitis. In the 1990's,
penicillin-resistant Streptococcus pneumoniae has accounted for 10% to 50%
(depending on geographic location) of all pediatric infections in day care
centers. During the years 1991 to 1994, the mortality rate in patients with
blood-borne strains of vancomycin-resistant enterococci was 57%, as compared to
approximately 35% for individuals infected with vancomycin--susceptible
strains.
 
                                       24
<PAGE>
 
  The increasing prevalence of antiinfective drug resistance is a natural
outcome of the use and overuse of antiinfective drugs. When bacteria or fungi
are exposed to an antiinfective drug, the drug kills or attenuates
the growth of the susceptible pathogen. However, any variant in the bacterial
population that has spontaneously undergone a genetic change that confers drug
resistance will have a selective growth advantage, which is known in
evolutionary terms as natural selection. Thus, the antiinfective drug does not
technically cause the resistance but creates a situation in which the
resistant pathogen can multiply in the presence of the drug, increasing the
population approximately a millionfold in a day and quickly becoming the
predominant microorganism. These resistant bacteria can then spread rapidly
from the infected patient to healthy individuals.
 
  Certain medical practices and sociological factors have facilitated and
accelerated the process of natural selection of drug-resistant bacteria and
fungi and help explain the increase in the rate at which pathogens are
becoming resistant to antiinfective drugs. These practices and factors
include: (i) the use of antibacterial drugs to treat non-bacterial infections,
(ii) the prophylactic use of antiinfective drugs to prevent potential but
unconfirmed infections, (iii) the use of antiinfective drugs active against
multiple pathogens (broad spectrum drugs) to treat an infection before the
specific disease-causing pathogen has been identified, (iv) the lack of
patient compliance with the prescribed course of antiinfective therapy and (v)
long-term antiinfective therapy for patients who are unable to clear
infections due to other conditions such as immunosuppression as a consequence
of organ transplants or cancer chemotherapy, or diseases such as AIDS.
 
  Bacteria and fungi have evolved multiple resistance mechanisms against
currently available categories of antiinfective drugs. These mechanisms
include: (i) utilization of an enzyme to alter the drug's structure by
creating or destroying chemical bonds, (ii) modification of the cell membrane
to block entry of the drug, (iii) utilization of a protein to pump the drug
out of their cells before the drug binds to the target and (iv) alteration of
the target to significantly limit the ability of the antiinfective drug to
bind to the target. Bacteria and fungi change the target by mutation of the
target's protein sequence, chemical modification of the target structure or
the acquisition of a new gene from another pathogen that substitutes for the
target function.
 
  Traditional drug discovery approaches have not met the challenge posed by
drug-resistant pathogens. To date, biology-based approaches have attempted to
identify compounds that kill or attenuate the growth of the pathogen using
whole-cell screening assays. This approach is limited because compounds that
could effectively inhibit a target function inside the cell, but are unable to
penetrate cell membranes, are not identified by whole-cell screening assays.
Thus, entire classes of effective inhibitors of intracellular targets, which
could be modified by medicinal chemistry to penetrate cell membranes, have
potentially been overlooked. Chemistry-based approaches have focused on
chemically modifying the molecular structure of existing antiinfective drugs
or combining existing antiinfective drugs with another agent (an antibiotic
potentiator) to circumvent established drug resistance mechanisms. Despite the
introduction of second and third generation antiinfective drugs, certain
pathogens, such as vancomycin-resistant strains of Enterococcus faecium, have
developed resistance to all currently available drugs. During the past 20
years, these traditional approaches have identified only one new chemical
class of antiinfective drugs to meet the challenge posed by drug-resistant
pathogens.
 
                                      25
<PAGE>
 
THE CUBIST SOLUTION
 
  Cubist is combating antiinfective drug resistance by identifying new targets
in bacteria or fungi which if inhibited by a drug would disrupt an essential
cell function and thereby kill or attenuate the growth of the pathogen,
allowing it to be cleared by the immune system. This rational, target-based
approach represents a distinct departure from traditional strategies to
develop drugs that only counter drug resistance. The Company has identified
over 100 proprietary targets and related assays for the discovery of new
drugs. The Company expects that drugs inhibiting these new targets would be
immediately effective against currently drug-resistant bacteria and fungi
since these pathogens have not had an opportunity to evolve resistance
specific to these new drugs. Furthermore, Cubist's most advanced drug
discovery program could identify a drug which inhibits more than one essential
target for a given pathogen, which would significantly decrease the rate of
emergence of drug resistance.
 
MARKET OPPORTUNITY
 
 Potential Market
 
  According to 1995 sales data compiled by IMS International, antiinfective
drugs generated $26 billion in sales and constituted the third largest
pharmaceutical market worldwide, behind only gastrointestinal and
cardiovascular drugs. The growth of the worldwide antiinfective drug market
from 1994 to 1995 was 13%. Of the 100 best-selling brand name drugs worldwide,
19 are antiinfective drugs addressing bacterial and fungal infections. In the
United States, sales of antiinfective drugs totaled over $7 billion in 1995,
and brand name antiinfective drugs accounted for 15 of the leading 100
prescription drugs.
 
  Antiinfective drugs are segmented into distinctive chemical classes, as
shown in the following table:
 
                         1995 ANTIINFECTIVE DRUG SALES
 
<TABLE>
<CAPTION>
     CHEMICAL CLASS      WORLDWIDE SALES    SELECTED EXAMPLES          INDICATED USE
- ------------------------ --------------- ------------------------ ------------------------
                          ($ millions)
<S>                      <C>             <C>                      <C>
ANTIBACTERIAL
 Beta Lactams
  Cephalosporins........     $8,540      Ceclor, Ceftriaxone,     Bronchitis, pneumonia,
                                         Cefuroxime               meningitis
  Penicillins...........      4,460      Ampicillin, Amoxicillin, Pneumonia, bronchitis,
                                         Amoxicillin/Clavulanate  otitis media, sinusitis
  Carbapenems...........        550      Imipenem                 Bacteremia, pneumonia,
                                                                  abdominal infections
 Fluoroquinolones.......      3,310      Ciprofloxacin, Ofloxacin Urinary tract
                                                                  infections,
                                                                  gastroenteritis,
                                                                  meningitis
 Macrolides.............      3,115      Clarithromycin,          Otitis media, sinusitis,
                                         Azithromycin,            skin and soft tissue
                                         Erythromycin             infections, meningitis
 Tetracyclines..........        743      Minocycline, Doxycycline Acne, pelvic
                                                                  inflammatory disease
 Aminoglycosides........        712      Gentamicin, Amikacin     Pneumonia, bacteremia,
                                                                  abdominal and urinary
                                                                  tract infections
 Glycopeptides..........        533      Vancomycin               Intestinal infections,
                                                                  Staphylococcus aureus
                                                                  infections
 Aminopyrimidines.......        380      Trimethoprim/Sulfonamide Bronchitis, urinary
                                                                  tract infections
ANTIFUNGAL
 Azoles.................      1,430      Fluconazole,             Vaginitis, skin and oral
                                         Itraconazole             infections, systemic
                                         Ketoconazole             infections
 Allylamines............        190      Terbinafine              Vaginitis, skin and oral
                                                                  infections, systemic
                                                                  infections
 Polyenes...............        190      Amphotericin B, Nystatin Meningitis, pneumonia,
                                                                  fungemia
</TABLE>
- --------
Source: IMS International (1996).
 
                                      26
<PAGE>
 
  Currently, several antiinfective drug classes generate over $1 billion in
annual worldwide sales. Within the cephalosporin class alone, there are six
drugs each with worldwide sales of between $300 million and $1.2 billion
annually. In addition, at least three drugs have individually reached
worldwide sales of over $1 billion annually: Augmentin
(amoxicillin/clavulanate) sold by SmithKline Beecham, Cipro (ciprofloxacin)
sold by Bayer Corp. and Rocephin (ceftriaxone) sold by Hoffmann-La Roche Inc.
Each of these drugs replaced previously prescribed drugs (such as penicillin,
tetracycline and erythromycin) whose effectiveness has greatly diminished as a
consequence of bacterial drug resistance. The clinical efficacy of these new
drugs, however, is similarly being threatened by emerging strains of drug-
resistant pathogens.
 
  Cubist is focusing its drug discovery programs on pathogens that have a high
annual incidence rate worldwide and that have become resistant to all but a
few available antiinfective drugs. The CDC has reported that 44% of the two
million hospital-acquired infections in the United States are caused by four
bacteria: staphylococci, enterococci, pneumococci and pseudomonas. The table
below lists the hospital and community-acquired pathogens that are the focus
of Cubist's drug discovery programs, the estimated annual incidence of
infectious disease caused by these pathogens, the types of infectious diseases
caused by these pathogens and the existing drugs to which these pathogens have
developed resistance.
 
                         CUBIST'S THERAPEUTIC TARGETS
 
<TABLE>
<CAPTION>
                      ESTIMATED                                  EXAMPLES OF
                        ANNUAL                                 DRUGS SUBJECT TO
      PATHOGEN       INCIDENCE(1)    PRINCIPAL DISEASES           RESISTANCE
- -------------------- ------------ ------------------------ ------------------------
<S>                  <C>          <C>                      <C>
BACTERIAL
 Staphylococcus au-   9,000,000   Skin and soft tissue     Methicillin, Beta
  reus..............              infections, bacteremia   Lactams
 Streptococcus        8,000,000   Otitis media, sinusitis, Penicillin, Beta Lactams
  pneumoniae........              pneumonia
 Escherichia coli...  4,800,000   Abdominal infections,    Ampicillin,
                                  urinary tract            Cephalosporins
                                  infections, bacteremia
 Haemophilus          1,000,000   Otitis media,            Ampicillin
  influenzae........              bronchitis, pneumonia
 Enterococcus           850,000   Urinary tract            Vancomycin, Beta Lactams
  faecium/faecalis..              infections, bacteremia
 Helicobacter pylo-     500,000   Gastritis, duodenal      Nitroimidazoles,
  ri................              ulcer                    Macrolides
 Pseudomonas            220,000   Pneumonia                Carbapenems,
  aeruginosa........                                       Aminoglycosides
 Mycobacterium tu-       25,000                            Rifampicin, Isoniazid
  berculosis........              Pneumonia
FUNGAL
 Candida albicans...  7,000,000   Vaginitis, skin          Fluconazole, Azoles
                                  infections, bacteremia,
                                  hepatitis
 Pneumocystis            60,000                            None documented(2)
  carinii...........              Pneumonia
 Aspergillus              8,000                            Azoles
  fumigatis/flavus..              Pneumonia
</TABLE>
- --------
(1) Cubist's estimate of the incidence in 1995 in the United States.
(2) Limited effective therapies available.
 
                                      27
<PAGE>
 
 Antiinfective Drug Development
 
  The pre-clinical and clinical development path for antiinfective drugs has
been well-established. A novel antiinfective drug has a high likelihood of
efficacy in humans if it has demonstrated (i) appropriate in vitro activity
against a broad spectrum of clinical pathogens, (ii) in vivo activity in
highly-predictive animal models of infection and (iii) effective
pharmacokinetics, such as half-life in the bloodstream.
 
  The FDA has indicated that antibiotic drugs may receive fast track approval
consideration if the antibiotics have been studied for their safety and
effectiveness in treating serious or life-threatening illnesses and the drugs
provide "meaningful therapeutic benefit" to patients over existing treatments
(for example, the ability to treat patients unresponsive to, or intolerant of,
available therapy, or improved patient response over available therapy). See
"Business--Government Regulation."
 
STRATEGY
 
  The Company's objective is to become the worldwide leader in the discovery
and development of novel antiinfective drugs to treat infectious diseases
caused by drug-resistant pathogens. To achieve this objective, the principal
elements of the Company's strategy are to:
 
  Pursue a Rational, Target-Based Approach to Drug Discovery. Cubist's
strategy for combating antiinfective drug resistance is to identify novel,
intracellular targets essential for cell function in bacteria or fungi which,
if inhibited by a drug, would kill or attenuate the growth of the pathogen.
The principal element of Cubist's drug discovery strategy is to rationally
select novel intracellular targets based on a thorough understanding of cell
function, thereby providing a foundation for assay development and lead
identification. Cubist believes that its rational, target-based strategy
represents a distinct departure from and offers significant advantages over
traditional drug discovery strategies to counter drug resistance.
 
  Establish a Pipeline of New Targets to Address Drug Resistance. Cubist
believes that bacterial and fungal pathogens will eventually develop
resistance against any drug by evolving resistance mechanisms that prevent the
drug from binding to and inhibiting the function of its intended target.
Therefore, Cubist's strategy for combating drug-resistant pathogens is to
identify new targets and develop novel drugs that act upon such targets. The
Company has identified over 100 proprietary targets and related assays for the
discovery of drugs. Furthermore, Cubist's most advanced drug discovery program
could identify a drug which inhibits more than one essential target for a
given pathogen, which would significantly decrease the rate of emergence of
drug resistance.
 
  Integrate Multiple Enabling Technologies. The Company's rational, target-
based approach to the discovery of novel drugs to combat drug-resistant
pathogens utilizes multiple enabling technologies, including genomics,
genetics, molecular biology, biochemistry, high-throughput screening,
medicinal and combinatorial chemistry, microbiology, pharmacology and
toxicology. The Company has assembled a team of scientists with expertise in
each of these disciplines and has successfully integrated these enabling
technologies into a drug discovery process involving the following stages:
target identification and validation, assay development, lead identification
and lead optimization. The Company believes that it has the internal
capability to advance a drug candidate through each of these stages.
 
  Establish Collaborative Relationships to Discover New Drugs and Broaden
Technology Base. The Company employs two collaborative strategies for the
discovery of new antiinfective drugs: (i) collaborations with major
pharmaceutical companies to provide the Company with funding, research and
development resources, access to libraries of diverse compounds and clinical
development, manufacturing and commercialization capabilities and
(ii) alliances with biopharmaceutical companies to access additional compound
libraries for the identification and optimization of lead candidates for the
Company's internal programs. The Company has entered into collaborative
agreements based upon the Synthetase Program with Bristol-Myers Squibb,
 
                                      28
<PAGE>
 
Merck and Pfizer. The Company believes that the Collaborative Agreements will
permit it to reduce its capital requirements and to leverage the development
expertise of its collaborative partners to accelerate the commercialization of
drug candidates. The Company has also entered into agreements with Terrapin
Technologies Inc., Pharm-Eco Laboratories, Inc. and ArQule, Inc. to obtain
additional compound libraries for Cubist's internal programs.
 
  Retain Rights to Independently Develop and Market Certain Products. Cubist
intends to continue to retain rights to internally develop and commercialize
certain proprietary products. This will enable the Company either to
commercialize certain drug candidates independently or to enter into future
drug development and commercialization alliances with third parties at a later
stage in the development process. The Company believes that this will enable
it to obtain greater economic benefits from future collaborations. Except for
rights granted to Bristol-Myers Squibb, Merck and Pfizer pursuant to the
Collaborative Agreements, the Company has retained rights to technology
related to its Synthetase Program for internal drug discovery. In addition,
the Ribonuclease P, Amidotransferase and Elongation Factors Programs are
currently being pursued with internal resources.
   
  Maintain and Enhance Strong Proprietary Position. Cubist plans to continue
to pursue an aggressive patent strategy to protect its proprietary drug
discovery technologies. The Company's policy is to diligently protect its
cloned targets, assays, organic synthetic processes, lead compounds, screening
technology and certain other technology. Cubist has eight pending U.S. patent
applications. In addition, Cubist has licensed three issued U.S. patents and
three pending U.S. applications covering inventions made by Dr. Paul R.
Schimmel and Dr. Julius Rebek, Jr., the two scientific founders of the
Company.     
 
                                      29
<PAGE>
 
THE CUBIST PROGRAMS
 
  Cubist's initial focus is on the identification and development of targets
that are involved in the fundamental process of protein synthesis. This
process involves a sequential order of well-established, enzymatic events that
leads to the incorporation of amino acids into proteins. Antiinfective drugs,
such as tetracyclines and erythromycin, that work by inhibiting protein
synthesis at the ribosome (a cellular component which is the site of
incorporation of amino acids into proteins) have been successfully developed
and commercialized. There are, however, several classes of essential enzyme
targets that function independently of the ribosome during protein synthesis
that have not yet been exploited as effective drug targets. The Company's
programs address targets in the areas of: (i) Synthetases, (ii) Ribonuclease
P, (iii) Amidotransferase and (iv) Elongation Factors. These enzyme targets
are essential for the survival of both bacterial and fungal pathogens. The
Company believes that these targets will enable the development of clinically
useful antiinfective drugs against susceptible and drug-resistant pathogens.
 
  The following table describes the various stages of development of Cubist's
four target-based programs.
 
 
 
                    [GRAPH OF PROGRAM STATUS APPEARS HERE]
 
 The Synthetase Program
 
  Synthetases are enzymes that play a fundamental role in protein synthesis in
all living organisms. In most organisms, there are 20 essential aminoacyl-tRNA
synthetases, one for each amino acid, which charge its specific amino acid to
a transfer RNA molecule ("tRNA") forming an amino acid-charged tRNA. These
charged tRNAs then interact with messenger RNA ("mRNA") at the ribosome to
incorporate the amino acid into the protein being synthesized. Inhibition of
any one of the 20 aminoacyl-tRNA synthetases from any bacterial or fungal
pathogen, at the amino acid or tRNA binding sites, would disrupt protein
production, thereby killing or attenuating the growth of the pathogen. As a
result, large numbers of targets, each with multiple sites of inhibition, are
available to Cubist for drug discovery. Furthermore, Cubist has demonstrated
that the molecular structures of bacterial or fungal synthetases are
sufficiently different from human synthetases to permit a drug to selectively
recognize and inhibit pathogen synthetases.
 
 
                                      30
<PAGE>
 
                   INHIBITION OF AMINOACYL - TRNA SYNTHETASE
                                     
                                  (ART)     
 
 
         PROTEIN                                INHIBITION OF PROTEIN
        SYNTHESIS                                     SYNTHESIS
 
 
     Binding of an amino                      Binding of an inhibitor to
     acid to the                              the aminoacyl - tRNA
     aminoacyl - tRNA                         synthetase alters the
     synthetase leads to                      synthetase structure,
     the formation of                         blocks amino acid binding
     charged tRNA and                         and prevents the formation
     protein synthesis                        of charged tRNA, thereby
                                              inhibiting protein
                                              synthesis
 
  Aminoacyl-tRNA synthetases provide a significant opportunity to combat
bacterial and fungal drug resistance derived from the resistance mechanism of
target alteration, which involves a change to the target's protein sequence,
chemical modification of the target structure or acquisition of a new gene
from another pathogen, substituting for the target function. Because there are
structural and functional similarities among the 20 aminoacyl-tRNA
synthetases, it may be possible to identify a drug that can bind to and
inhibit two similar synthetases, thereby decreasing the rate of emergence of
drug resistance. Thus, a resistance mechanism involving target alteration
would necessitate simultaneous changes in two of the targets. From a
statistical standpoint, the probability of simultaneous alteration of two
targets would be extremely low. Therefore, a single drug active against more
than one aminoacyl-tRNA synthetase would be likely to have the advantage of an
extended therapeutic lifetime by significantly impeding the future emergence
of drug resistance.
 
  Clinical precedent exists for the development of a bacterial aminoacyl-tRNA
synthetase inhibitor. Pseudomonic acid A, commercially marketed as Bactroban,
is an antibacterial drug that is a specific inhibitor of isoleucyl-tRNA
synthetase in several pathogens, including Staphylococcus aureus. The drug can
be used only as a topical agent, however, because it is unstable in the
bloodstream and therefore is not therapeutically effective when administered
systemically. Cubist's goal is to develop systemically-available drugs that
target aminoacyl-tRNA synthetases in either bacteria or fungi.
 
  The Company has developed over 100 proprietary aminoacyl-tRNA synthetase
targets and related assays that are currently being utilized in the discovery
and characterization of leads in its Synthetase Program. These aminoacyl-tRNA
synthetase targets were cloned or purified from Streptococcus pneumoniae,
Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Haemophilus
influenzae, Mycobacterium tuberculosis and Helicobacter pylori
 
                                      31
<PAGE>
 
bacteria, Candida albicans and Pneumocystis carinii fungi and cultured human
cells. The Company is currently developing assays and pursuing targets in
additional pathogens, such as Pseudomonas aeruginosa and Aspergillus
fumigatus.
 
  In its search for leads, Cubist combines automated, high-throughput
screening of its compound libraries with a rational drug design approach.
Cubist has synthesized molecules that structurally mimic the biochemical
intermediates that are formed during the charging of tRNA by aminoacyl-tRNA
synthetase enzymes. These structural mimics bind to the active site of the
enzyme and preclude the amino acid and other substrates from binding, thereby
inhibiting enzyme function. Using this approach, Cubist has discovered several
proprietary leads that inhibit certain aminoacyl-tRNA synthetases. Leads from
Cubist's rational drug design program as well as those identified through
screening compound libraries are currently being optimized to improve
stability, potency, selectivity, whole cell activity and efficacy in animal
models in an effort to identify clinical development candidates.
 
  The Company has entered into agreements based on certain targets within the
Synthetase Program with Bristol-Myers Squibb, Merck and Pfizer. Under these
collaborations, the small molecule compound libraries of Cubist's
collaborative partners are screened for inhibitors of certain aminoacyl-tRNA
synthetases in enzyme assays developed by the Company. Inhibitors are then
characterized for their spectrum of inhibition against a variety of pathogens
as well as for selectivity and whole cell activity using an additional set of
Cubist's assays. Lead candidates which are selected by the collaborative
partners will then enter into a drug development program where medicinal
chemistry, microbiology and pharmacology studies will be conducted to optimize
the leads into drug candidates. The Company has also retained certain rights
to this technology for use in its internal programs. See "Collaborative
Agreements."
 
  Cubist expects to complete the optimization of a lead from its internal
Synthetase Program efforts to select a drug candidate for pre-clinical
development by the end of 1996. Assuming successful pre-clinical development,
Cubist expects to file an IND by the end of 1997. Assuming successful
development of a drug candidate under one or more of its Collaborative
Agreements, Cubist believes a collaborative partner could file an IND as early
as the end of 1998.
 
 The Ribonuclease P Program
 
  The Company's Ribonuclease P Program focuses on the discovery of
antiinfective drugs that inhibit ribonuclease P ("RNase P"), an essential
target in the process of protein synthesis. All tRNAs are initially
synthesized as immature tRNA molecules which are cleaved to the required
functional size and structure by an essential enzyme, RNase P. Inhibition of
RNase P will thus prevent the maturation of tRNA molecules, an essential step
in protein synthesis, thereby killing or attenuating the growth of the
pathogen.
 
              [PICTURE OF RIBONUCLEASE P AND tRNA APPEARS HERE]
 
 
   RIBONUCLEASE P (RNASE P) BINDS TO AND CLEAVES IMMATURE TRNA MOLECULES TO
                             PRODUCE MATURE TRNAS
 
                                      32
<PAGE>
 
  Because RNase P has both RNA and protein components, each can serve as a
target for inhibition. To date, research has shown that both the bacterial RNA
and protein components of RNase P differ from those found in certain mammals.
The Company believes that the differences between the human and bacterial
RNase P enzymes indicate that the bacterial RNase P can be selectively
inhibited.
 
  Cubist has cloned, sequenced and expressed the genes encoding both the
protein and the RNA components of RNase P from certain bacteria. Recombinant
RNase P enzymes that have demonstrated the ability to cleave immature tRNA
serve as the foundation for biological assays. The Company is currently
developing an automated in vitro enzyme assay feasible for high-throughput
screening to identify inhibitors of bacterial RNase P. The Company expects to
commence high-throughput screening for the identification of inhibitors of
RNase P activity in the first quarter of 1997.
 
 The Amidotransferase Program
 
  The Company's Amidotransferase Program focuses on the discovery of
antiinfective drugs that inhibit glutamine amidotransferase ("AdTase"), an
essential target in the process of protein synthesis. Certain bacteria have
only 19 of the 20 required aminoacyl-tRNA synthetases and lack glutamine-tRNA
synthetase. These bacteria still require all 20 amino acids for protein
synthesis and therefore have developed a two-step process to compensate for
the lack of glutamine aminoacyl-tRNA synthetase. In step one, glutamate-tRNA
synthetase attaches glutamate to both glutamate-tRNA and glutamine-tRNA. In
step two, AdTase modifies the glutamate that is charged to the glutamine-tRNA
into glutamine, the appropriate amino acid. The now correctly charged tRNA can
incorporate the amino acid glutamine into the growing protein chain.
Inhibiting AdTase activity would thus limit the synthesis of all proteins that
require glutamine, thereby killing or attenuating the growth of the pathogen.
Mammalian cells do not need AdTase because they have a glutamine-tRNA
synthetase. Therefore, an inhibitor of AdTase is expected to be inherently
selective for the bacterial enzyme.
 
                                              GLUTAMATE
 
                                                        GLUTAMINE
 
      [PICTURE OF AMIDOTRANSFERASE MODIFYING GLUTAMATE tRNA APPEARS HERE]
 
 CERTAIN BACTERIA LACK GLUTAMINE TRNA SYNTHETASE AND REQUIRE
 AMIDOTRANSFERASE (ADTASE) TO BINDTO AN INAPPROPRIATELY CHARGED TRNA AND
 MODIFY THE AMINO ACID GLUTAMATE TO GLUTAMINE.
 
  The Company has established that AdTase activity is present in certain
bacteria, including Staphylococcus aureus and Enterococcus faecalis. The
Company has developed an assay to monitor the function of this enzyme. Cubist
is currently adapting this assay for automated, high-throughput screening and
expects to commence such screening for the identification of inhibitors of
AdTase activity in the second half of 1997.
 
                                      33
<PAGE>
 
 The Elongation Factors Program
 
  The Company's Elongation Factors Program focuses on the discovery of
antiinfective drugs that inhibit elongation factors Tu (EF-Tu) and Ts (EF-Ts),
essential protein targets in the process of protein synthesis. EF-Tu
transports amino acid-charged tRNA to the ribosome and also plays a role in
the continuing synthesis of proteins. During this process EF-Tu becomes
inactivated and its reactivation requires a second elongation factor, EF-Ts. A
crystal structure of EF-Tu associated with some of its substrates including
EF-Ts, has been defined. Inhibition of either EF-Tu or EF-Ts activity will
inhibit protein synthesis and kill or attenuate the growth of the pathogen.
The Company believes that based upon identified structural differences between
the bacterial and humans elongation factors, the bacterial enzymes can be
selectively inhibited.
 
    EF-TU
                                                                        PROTEIN
 
                                                        MRNA
 
                                 RIBOSOME
               [PICTURE OF ELONGATION FACTOR TU, CHARGED tRNA,
               RIBOSOME, mRNA, AND PROTEIN CHAIN APPEARS HERE]

    ELONGATION FACTOR EF-TU BINDS TO CHARGED TRNA AND TRANSPORTS IT TO THE
                        RIBOSOME FOR PROTEIN SYNTHESIS.
 
  Cubist has cloned, sequenced and expressed the genes encoding the EF-Tu and
EF-Ts proteins. Cubist is currently developing an assay for automated, high-
throughput screening and expects to commence such screening for the
identification of inhibitors of EF-Tu and EF-Ts activity in the second half of
1997.
 
 Other Target Discovery Programs
 
  The Company is currently utilizing genomic information to develop additional
biological screening assays for drug discovery. Strategically, the Company
will continue to investigate targets involved in protein synthesis and will
broaden its focus to include additional targets outside of this area, for
example, protein-DNA interactions and cell metabolism.
 
 
                                      34
<PAGE>
 
DRUG DISCOVERY TECHNOLOGIES
 
  The Cubist drug discovery process consists of four primary steps as part of
an integrated platform: (i) target identification and validation, (ii) assay
development, (iii) lead identification and (iv) lead optimization.
 
 
            [GRAPH OF CUBIST'S DRUG DISCOVERY PROCESS APPEARS HERE]
 
  TARGET IDENTIFICATION AND VALIDATION--the use of microbial genomics and
functional genetics to identify multiple targets for drug discovery. The
Company uses a rational target selection approach which incorporates microbial
genomics and functional genetics to identify and characterize targets. To be
selected for entry into a drug discovery program, targets must be: (i)
essential for the life of the pathogen, so that inhibition of the target's
natural function will kill or attenuate the growth of the pathogen, (ii)
functionally characterized for assay development prior to high-throughput
screening and (iii) structurally divergent between bacteria or fungi and humans
so that the pathogen target can be selectively inhibited.
 
  Cubist utilizes functional genetics to determine whether a particular target
is essential to the survival of the cell. Pathogen death following the
disruption or deletion of a gene encoding the target conclusively establishes
the essential nature of the target. The prevalence of a particular target among
different species of bacteria and fungi defines its spectrum. Structural
divergence between pathogen and human genes suggests the potential for
identifying compounds with selectivity for the pathogen.
 
  ASSAY DEVELOPMENT--the use of molecular biology, biochemistry and enzymology
to characterize targets and validate high-throughput screening assays. Cubist
has built significant assay development capabilities which are an important
component of its proprietary drug discovery programs. Assay quality is the most
important determinant of any screening program's productivity. Established
molecular biology tools enable Cubist to rapidly clone, sequence, express and
purify multiple targets. Cubist then utilizes enzymology and biochemistry
techniques to functionally characterize targets. By characterizing these
targets, Cubist can develop robust, sensitive high-throughput screening assays.
The Company utilizes these assays to identify inhibitors. Cubist employs
proprietary screens to provide a quantitative description of potency, spectrum
and selectivity. In addition, the Company's enzymology studies identify
reaction mechanisms that provide the basis for rational drug design.
 
  LEAD IDENTIFICATION--the use of high-throughput screening of small molecule
libraries, combinatorial chemistry and rational drug design to identify
potential drug candidates. Cubist has implemented automation and robotics to
perform high-throughput screening to address a critical rate-limiting step in
drug discovery: the large number of assays required to empirically screen
synthetic and natural product compound libraries to identify novel inhibitors.
Cubist has achieved a screening throughput rate of 1.5 million compounds per
year through the implementation of robotics and other enhancement techniques,
such as the simultaneous assay of mixtures of compounds. Novel inhibitors are
further characterized using Cubist's secondary screens consisting of
increasingly stringent selection criteria (such as spectrum and selectivity) to
identify drug candidates with the greatest potential for successful
development.
 
                                       35
<PAGE>
 
  To date, Cubist has assembled a library of over 135,000 structurally-diverse
synthetic small molecules for screening against each of its 100 proprietary
targets. Molecules used in the Cubist screening program currently originate
from four sources: (i) Cubist's proprietary rational design chemistry
programs, (ii) Cubist's proprietary combinatorial chemistry programs, (iii)
academic and industrial collaborations and (iv) commercial sources. Based on
the current rate of growth of the compound collection, the Company estimates
that the number of compounds available for high-throughput screening in its
proprietary programs will more than double during the next year. In addition,
the Company believes that the Collaborative Agreements provide it with access
to additional libraries of over one million structurally diverse molecules for
lead identification.
 
  The Cubist combinatorial chemistry program generates two types of libraries,
general and lead-specific. The general libraries are designed to provide
Cubist with a diversity of molecular structures which can be used in
conjunction with high-throughput screening to identify novel lead compounds
which inhibit selected targets. Cubist constructs lead-specific libraries
based on principles of rational drug design using structural templates
demonstrated to interact with the aminoacyl-tRNA synthetases. Cubist's
proprietary general and lead-specific libraries are being used to identify new
lead inhibitors of the aminoacyl-tRNA synthetases and other enzyme targets.
 
  LEAD OPTIMIZATION--the use of medicinal chemistry, high speed analoging and
pre-clinical evaluation to enhance pharmaceutical properties. Cubist optimizes
lead compounds, which have been identified by its high-throughput screening
and rational drug design approaches, through the iterative use of medicinal
chemistry and in vitro biological assays to enhance pharmaceutical properties.
These lead compounds first enter a high-speed chemical analoging program which
generates large numbers of structurally-related compounds. These analogs are
then evaluated for their (i) spectrum of inhibitory potency against a given
enzyme from a variety of pathogens, (ii) selectivity of the pathogen against
the human enzyme, (iii) inhibitory potency against multiple targets from a
single pathogen to identify a compound that could inhibit more than one target
and (iv) spectrum of activity against whole cells, including drug-resistant
strains, to determine potential clinical indication. Cubist subsequently
evaluates, in animal models, drug candidates exhibiting suitable potency,
spectrum and selectivity to determine their pharmacological and toxicological
properties.
 
COLLABORATIVE AGREEMENTS
 
  A key element of the Company's strategy is to enter into collaborations with
major pharmaceutical companies to develop its initial products. These
collaborations are expected to provide the Company with funding, research and
development resources, and access to libraries of diverse compounds and
clinical development, manufacturing and commercialization capabilities. To
date, the Company has entered into agreements based on certain targets within
the Synthetase Program with Bristol-Myers Squibb, Merck and Pfizer to screen
the collaborators' respective compound libraries against certain aminoacyl-
tRNA synthetase targets. Assuming that the Collaborative Agreements continue
until their scheduled expirations, and that a separate drug is successfully
developed and commercialized from each of the five research programs to be
conducted pursuant to these agreements, Cubist will be entitled to receive a
total of $98.5 million in research support payments, technology licensing
fees, milestone payments and equity investments. In addition, the Company will
be entitled to receive royalties on worldwide sales of drugs resulting from
these collaborations. Through July 1996, the Company's collaborative partners
have provided the Company with $3.8 million of research support payments and a
technology licensing fee and $4.0 million in equity investments.
 
                                      36
<PAGE>
 
 Bristol-Myers Squibb
 
  In June 1996, the Company and Bristol-Myers Squibb entered into the Bristol-
Myers Squibb Agreement pursuant to which they agreed to collaborate to
discover and develop novel antiinfective drugs from leads obtained by
screening six of Cubist's aminoacyl-tRNA synthetase targets against Bristol-
Myers Squibb's compound library. In connection with the signing of the
Bristol-Myers Squibb Agreement, Bristol-Myers Squibb made a $4.0 million
equity investment in the Company. See "Certain Transactions." If a separate
drug is successfully developed and commercialized through each of the
bacterial, mycobacterial and fungal programs within the collaboration, Cubist
will be entitled to receive a total of $56.5 million in research support
payments, technology licensing fees, milestone payments and other payments
from Bristol-Myers Squibb, including an equity investment of $4.0 million made
in June 1996. The development, manufacture and worldwide sale of drugs
resulting from the collaboration will be conducted by Bristol-Myers Squibb,
and the Company will be entitled to receive royalties on the worldwide sales
of any drug developed and commercialized from this collaboration. Cubist has
granted Bristol-Myers Squibb an exclusive worldwide license to conduct
research and drug development of drug candidates resulting from this
collaboration. There can be no assurance that any drug candidates will be
discovered through the collaboration or that if discovered, Bristol-Myers
Squibb will elect to proceed with the development of any drug candidates.
Under the terms of the Bristol-Myers Squibb Agreement, Bristol-Myers Squibb is
not obligated to develop or commercialize any drug candidates. As a result,
there can be no assurance that any of the milestone or royalty payments
contemplated by the Bristol-Myers Squibb Agreement will be made.
 
 Merck
 
  In June 1996, the Company and Merck entered into the Merck Agreement
pursuant to which they agreed to collaborate to discover and develop novel
antiinfective drugs from leads obtained by screening three of Cubist's
aminoacyl-tRNA synthetase targets against Merck's compound library. If a drug
is successfully developed and commercialized through this collaboration,
Cubist will be entitled to receive $20.5 million in research support payments,
technology licensing fees and milestone payments from Merck. The development,
manufacture and worldwide sale of drugs resulting from the collaboration will
be conducted by Merck, and the Company will be entitled to receive royalties
on the worldwide sales of any drug developed and commercialized from this
collaboration. Cubist has granted Merck an exclusive worldwide license to
commercialize drugs resulting from this collaboration. There can be no
assurance that any drug candidates will be discovered through the
collaboration or that, if discovered, Merck will elect to proceed with the
development of any drug candidates. Under the terms of the Merck Agreement,
Merck is not obligated to develop or commercialize any drug candidates. As a
result, there can be no assurance that any of the milestone or royalty
payments contemplated by the Merck Agreement will be made.
 
 Pfizer
 
  In December 1995, the Company and Pfizer entered into the Pfizer Agreement
pursuant to which they agreed to collaborate to discover and develop novel
antiinfective drugs from leads obtained by screening six of Cubist's
aminoacyl-tRNA synthetase targets against Pfizer's compound library. If a drug
is successfully developed and commercialized through this collaboration,
Cubist will be entitled to receive $21.5 million in research support payments,
technology licensing fees, milestone payments and other payments from Pfizer,
including a $5.0 million equity investment. The development, manufacture and
sale of drugs worldwide resulting from the collaboration will be conducted by
Pfizer, and the Company will be entitled to receive royalties on the worldwide
sales of any drug developed and commercialized from this collaboration. Cubist
has granted Pfizer an exclusive worldwide license to commercialize drugs
resulting from this collaboration. There can be no assurance that any drug
candidates will be discovered during the collaboration or that, if discovered,
Pfizer will elect to proceed with the development of any drug candidates.
Under the terms of the Pfizer Agreement, Pfizer is not obligated to develop or
commercialize any drug candidates. As a result, there can be no assurance that
any of the milestone or royalty payments contemplated by the Pfizer Agreement
will be made.
 
                                      37
<PAGE>
 
  The Company is dependent on its collaborative partners for drug development,
obtaining regulatory approvals and other resources for drug candidates
emerging from these collaborations. See "Risk Factors-- Dependence on
Collaborative Partners and Others" and "Risk Factors--Future Capital Needs;
Uncertainty of Additional Funding."
 
 Other Collaborations
 
  To obtain additional compound libraries for further expansion of the
Company's internal drug discovery programs, Cubist has entered into agreements
with Terrapin Technologies Inc., Pharm-Eco Laboratories, Inc. and ArQule, Inc.
If a drug is successfully developed and commercialized as a result of any of
these agreements, Cubist is granted a license to commercialize the drug and
will pay royalties to its partner on commercial sales. In addition, Cubist has
entered into an agreement with Ceregen, a division of Monsanto Company,
permitting coded access to the Company's combinatorial chemistry library for
screening against certain agricultural targets. If Ceregen successfully
develops and commercializes a product as a result of the agreement, Cubist
will be entitled to royalties on sales.
 
PATENTS AND PROPRIETARY TECHNOLOGY
   
  Proprietary protection for the Company's compounds, technology and processes
is important to its business. The Company's policy is to diligently protect
its cloned targets, assays, organic synthetic processes, lead compounds,
screening technology and certain other technology by, among other things,
filing, or causing to be filed on its behalf, patent applications for
technology relating to the development of its business in the United States
and elsewhere. To date, the Company has received a notice of allowance for two
of these applications covering an isolated recombinant nucleic acid encoding
mycobacterial seryl-tRNA synthetase and processes of making mycobacterial
seryl-tRNA synthetases. Cubist has 8 pending U.S. patent applications. In
addition, Cubist has licensed three U.S. patents and three U.S. patent
applications.     
 
  Patent law, as it relates to inventions in the pharmaceutical and
biotechnology fields, is still evolving and involves complex legal and factual
questions for which legal principles are not firmly established. Moreover,
because (i) patent applications in the United States are maintained in secrecy
until patents issue, (ii) patent applications in certain other countries
generally are not published until more than eighteen months after they are
filed, (iii) publication of technological developments in the scientific or
patent literature often lags behind the date of such developments and (iv)
searches of prior art may not reveal all relevant prior inventions, the
Company cannot be certain that it was the first to invent the subject matter
covered by its patent applications or that it was the first to file patent
applications for such inventions. Accordingly, there can be no assurance that
patents will be granted with respect to any of the Company's pending patent
applications or with respect to any patent applications filed by the Company
in the future.
 
  The commercial success of the Company will depend in part on not infringing
patents or proprietary rights of others. There can be no assurance that the
Company will be able to obtain a license to any third-party technology it may
require to conduct its business or that if obtainable, such technology can be
licensed at reasonable cost. Failure by the Company to obtain a license to
technology that it may require to utilize its technologies or commercialize
its products may have a material adverse effect on the Company's business,
operating results and financial condition. In some cases, litigation or other
proceedings may be necessary to defend against or assert claims of
infringement, to enforce patents issued to the Company, to protect trade
secrets, know-how or other intellectual property rights owned by the Company,
or to determine the scope and validity of the proprietary rights of third
parties. Any potential litigation could result in substantial costs to and
diversion of resources by the Company and could have a material adverse effect
on the Company's business, operating results and financial condition. There
can be no assurance that any of the Company's issued or licensed patents would
ultimately be held valid or that efforts to defend any of its patents, trade
secrets, know-how or other intellectual property rights would be successful.
An adverse outcome in any such litigation or proceeding could subject the
Company to significant liabilities, require the Company to cease
 
                                      38
<PAGE>
 
using the subject technology or require the Company to license the subject
technology from the third party, all of which could have a material adverse
effect on the Company's business, operating results and financial condition.
 
  Much of the know-how of importance to the Company's technology and many of
its processes are dependent upon the knowledge, experience and skills, which
are not patentable, of key scientific and technical personnel. To protect its
rights to and to maintain the confidentiality of trade secrets and proprietary
information, the Company requires employees, Scientific Advisory Board
members, consultants and collaborators to execute confidentiality and
invention assignment agreements upon commencement of a relationship with the
Company. These agreements prohibit the disclosure of confidential information
to anyone outside the Company and require disclosure and assignment to the
Company of ideas, developments, discoveries and inventions made by employees,
advisors, consultants and collaborators. There can be no assurance, however,
that these agreements will not be breached or that the Company's trade secrets
or proprietary information will not otherwise become known or developed
independently by others. See "Risk Factors--Uncertainty of Patents and
Proprietary Rights."
 
GOVERNMENT REGULATION
 
 Overview
 
  Regulations imposed by United States federal, state and local authorities,
as well as their counterparts in other countries, are a significant factor in
the conduct of the research, development, manufacturing and marketing
activities for the Company's potential drug candidates.
 
  The development, manufacture and marketing of drugs (including antibiotics)
developed by the Company or its collaborative partners are subject to
regulation by numerous governmental agencies in the United States, principally
the FDA, by state and local governments, and in some instances by foreign
governments. Pursuant to the Federal Food, Drug, and Cosmetic Act and the
regulations promulgated thereunder (the "FDC Act"), the FDA regulates the pre-
clinical and, clinical trials, safety, effectiveness, manufacture, labeling,
storage, distribution, and promotion of drugs. Noncompliance with applicable
requirements can result in, among other things, fines, injunctions, recall or
seizure of products, total or partial suspension of production, refusals to
permit products to be imported into or exported out of the United States,
failure of the government to grant approval for new drugs or antibiotic
products, withdrawal of marketing approvals, denial or suspension of
government contracts and criminal prosecution.
 
  Product development and approval within the FDA regulatory framework usually
takes a significant number of years, involves the expenditure of substantial
capital resources and is uncertain. Moreover, there is no assurance that the
current regulatory framework will not change or that additional regulatory
standards will not be promulgated at any stage of the Company's or its
collaborative partners' product development that may adversely affect
approval, delay the submission or review of an application or require
additional expenditures by the Company.
 
 U.S. Regulatory Process
   
  New drugs (as well as antibiotics not subject to certification) must be
found safe and effective by FDA through the approval of a new drug application
("NDA") pursuant to section 505 of the FDC Act prior to marketing in
interstate commerce. Prior to this, the pre-clinical data (animal and in vitro
laboratory data) and clinical data (human data) are regulated by FDA pursuant
to regulations and the issuance and continuing FDA oversight of an
investigational new drug application ("IND"). Post-NDA approval, FDA maintains
continuing regulatory control over the marketing of approved drugs regulating
most closely manufacturing, promotional activities and the appropriate
submission of adverse reaction information. Any material changes to the
indication for use, other labeling or manufacturing, require FDA approval of a
Supplement to the NDA prior to any such change being made.     
 
  Before testing in the United States of any compounds with potential
therapeutic value in human test subjects may begin, stringent government
requirements for preclinical data must be satisfied. Pre-clinical testing
includes both in vitro and in vivo laboratory evaluation and characterization
of the safety and efficacy
 
                                      39
<PAGE>
 
of a drug and its formulation. Laboratories involved in pre-clinical testing
must comply with FDA regulations regarding Good Laboratory Practices. Pre-
clinical testing results obtained from studies in several animal species, as
well as from in vitro studies, are submitted to the FDA as part of the IND and
are reviewed by the FDA prior to the commencement of human clinical trials.
These pre-clinical data must provide an adequate basis for evaluating both the
safety and the scientific rationale for the initial (Phase I) studies in human
volunteers. Unless the FDA objects to an IND, the IND becomes effective 30
days following its receipt by the FDA. There can be no assurance that
submission of an IND will result in the commencement of human clinical trials.
Moreover, once trials have commenced, the FDA may stop the trials by placing
them on "clinical hold" because of concerns about, for example, the safety of
the product being tested. Such clinical holds either before the clinical
studies commence or after commencement may result in either a temporary halt
to the study or abandonment of any further work whatsoever.
   
  Clinical trials, which involve the administration of the investigational
drug to healthy volunteers or to patients under the supervision of a qualified
principal investigator, are typically conducted in three sequential phases,
although the phases may overlap with one another. Clinical trials must be
conducted in accordance with the FDA's Good Clinical Practices, under
protocols that detail the objectives of the study, the parameters to be used
to monitor safety and the efficacy criteria to be evaluated. Each protocol
must be submitted to the FDA as part of the IND. Further, each clinical study
must be conducted under the auspices of an independent Institutional Review
Board (the "IRB") at the institution where the study will be conducted. The
IRB will consider, among other things, ethical factors, the safety of human
subjects, informed consent requirements and the possible liability of the
institution. Compounds must be formulated according to FDA's current Good
Manufacturing Practice regulations ("cGMP").     
 
  Clinical testing involves the administration of the drug to healthy human
volunteers or to patients under the supervision of a qualified investigator,
usually a physician, pursuant to an FDA-reviewed protocol. Human clinical
trials are typically conducted in three sequential phases.
 
  Phase I clinical trials represent the initial administration of the
investigational drug to a small group of healthy human subjects or, more
rarely, to a group of selected patients with the targeted disease or disorder.
The goal of Phase I clinical trials is typically to test for safety (adverse
effects), dose tolerance, absorption, biodistribution, metabolism, excretion
and clinical pharmacology and, if possible, to gain early evidence regarding
efficacy.
 
  Phase II clinical trials involve a small sample of the actual intended
patient population and seek to assess the efficacy of the drug for specific
targeted indications, to determine dose tolerance and the optimal dose range
and to gather additional information relating to safety and potential adverse
effects.
 
  Once an investigational drug is found to have some efficacy and an
acceptable safety profile in the targeted patient population, Phase III
clinical trials are initiated to establish further clinical safety and
efficacy of the investigational drug in a broader sample of the general
patient population at geographically dispersed study sites in order to
determine the overall risk-benefit ratio of the drug and to provide an
adequate basis for product labeling. The Phase III clinical development
program consists of expanded, large-scale studies of patients with the target
disease or disorder, to obtain definitive statistical evidence of the efficacy
and safety of the proposed product and dosage regimen. These studies may
include investigation of the effects in subpopulations of patients, such as
the elderly, children, etc. All of the phases of clinical studies must be
conducted in conformance with the FDA's bioresearch monitoring regulations
(such as IRB, informed consent and sponsor monitoring requirements).
 
  At the same time that the human clinical program is being performed,
additional non-clinical (animal) studies are also conducted. Expensive, long
duration toxicity and carcinogenicity studies are done to demonstrate the
safety of drug administration for the extended period of time required for
effective therapy. Also, a variety of laboratory, animal and initial human
studies are performed to establish manufacturing methods for delivering the
drug, as well as stable, effective dosage forms.
 
 
                                      40
<PAGE>
 
  Unless exempted by specific regulation, antibiotic products are subject to
additional FDA regulations that pertain to batch certification requirements.
In general, the regulations require testing and certification of each batch of
an antibiotic drug for compliance with the FDA's monograph regulations. If the
FDA determines that the batch conforms to the applicable standards of
identity, strength, quality and purity found in the specific monograph, the
FDA will issue a certificate attesting that the batch conforms to the
applicable monograph standards. Manufacturers also are required to comply with
certain recordkeeping requirements that pertain to certification. If a given
batch does not comply with the stated requirements, the FDA will refuse to
certify the batch and the manufacturer will be prohibited from marketing the
product.
 
  Antibiotic drugs for human use are exempt from batch certification if
certain conditions are satisfied. For example, in the case of an over-the-
counter ("OTC") antibiotic subject to an FDA OTC drug monograph, the drug will
be exempt from batch certification if the drug satisfies the conditions
specified in the applicable OTC drug monograph. For prescription antibiotics,
a drug may be exempt from batch certification if certain other conditions are
satisfied, including among others, that the antibiotic has been approved by
the FDA in an applicable antibiotic application for marketing, and that the
antibiotic product meets the standard of identity, strength, quality and
purity specified in an applicable monograph or in the applicable approved
antibiotic application. Once an antibiotic drug has been approved as safe and
effective, the FDA promulgates a regulation of general applicability,
describing in detail the required specifications of the drug. Thereafter,
anyone who meets the standards in that regulation may obtain FDA clearance for
his or her own product without submission of any data on safety and
effectiveness, other than data demonstrating bioequivalence to the original
product.
   
  All data obtained from a comprehensive development program including
research and product development, manufacturing, pre-clinical and clinical
trials and related information are submitted in an NDA to the FDA and the
corresponding agencies in other countries for review and approval. In addition
to reports of the trials conducted under the IND application, the NDA includes
information pertaining to the preparation of the new drug or antibiotic,
analytical methods, details of the manufacture of finished products and
proposed product packaging and labeling. Although the FDC Act requires the FDA
to review NDAs within 180 days of their filing, in practice longer times may
be required. The FDA also frequently requests that additional information be
submitted, requiring significant additional review time. As a result of the
Prescription Drug User Fee Act, FDA has made commitments to speed the review
of NDAs and NDA Supplements. While implementation of this by the FDA has sped
up certain decision-making by the FDA, it has not, with regard to many drugs,
sped up the overall development and approval time. Any proposed product of the
Company likely would be subject to demanding and time-consuming NDA approval
procedures in virtually all countries where marketing of the products is
intended. These regulations define not only the form and content of safety and
efficacy data regarding the proposed product but also impose specific
requirements regarding manufacture of the product, quality assurance,
packaging, storage, documentation and recordkeeping, labeling, advertising and
marketing procedures.     
 
  The FDA has developed two "fast track" policies for certain new drugs, one
policy for expedited development and review, and one policy for accelerated
approval. The expedited review policy applies to new drug therapies, including
antibiotics, that are intended to treat persons with life-threatening and
severely-debilitating illnesses, especially where no satisfactory alternative
therapy exists. The FDA has defined "severely-debilitating" to mean diseases
or conditions that cause major irreversible morbidity. During the
developmental stage of drugs that qualify, the FDA expedites consultation and
review of these experimental therapies.
 
  The FDA's accelerated approval policy applies to certain new drug or
antibiotic products that have been studied for their safety and effectiveness
in treating serious or life-threatening illnesses and that provide "meaningful
therapeutic benefit to patients over existing treatments." This accelerated
approval, or fast track approach, is generally limited to new drugs or
antibiotics that treat patients that are unresponsive to, or
 
                                      41
<PAGE>
 
intolerant of, available therapy, or when there is improved patient response
over currently available therapy. The accelerated approval policy is further
limited to drugs for which the predictive value of the surrogate endpoint, in
terms of clinical outcome, has not been established. At the time of approval,
the FDA may grant approval on a surrogate endpoint or an effect on a clinical
endpoint other than survival or irreversible morbidity. The FDA may impose
certain restrictions on distribution, limiting its use to certain facilities
or specialty-trained physicians or making its use contingent on the
performance of certain specified medical procedures. Postmarketing studies
(Phase IV trials) are usually required to further affirm safety and/or
efficacy. However, if an acceptable clinical endpoint has been established,
the drug must be evaluated for approval under the traditional (non-fast track)
approach.
 
  The FDA determines when a specific new drug or antibiotic product qualifies
for accelerated review. There is no guarantee that an application submitted
for a new drug or antibiotic product will receive fast track consideration by
the FDA or that the FDA will approve an NDA for such drug or antibiotic
product once it has been reviewed. Moreover, the FDA may grant marketing
approval and simultaneously require postmarketing studies. And, the FDA may
subsequently withdraw approval of a new drug or antibiotic product if a
postmarketing study fails to verify the clinical benefit of the new drug or
antibiotic.
 
  Timetables for the various phases of clinical trials and NDA approval cannot
be predicted with any certainty. The Company, its collaborative partners or
the FDA may suspend clinical trials at any time if it is believed that
individuals participating in such trials are being exposed to unacceptable
health risks. Even assuming that clinical trials are completed and that an NDA
is submitted to the FDA, there can be no assurance that the NDA will be
reviewed by the FDA in a timely manner or that once reviewed, the NDA will be
approved. The approval process is affected by a number of factors, including
the severity of the targeted indications, the availability of alternative
treatments and the risks and benefits demonstrated in clinical trials. The
Company's ability to market its products successfully is further dependent on
the patent and marketing exclusivity rights of a competitor's products. With
regard to marketing exclusivity, the FDC Act provides for 5 years of marketing
exclusivity for new chemical entities having received an NDA. In addition,
NDAs or NDA Supplements for other new drugs may receive 3 years of marketing
exclusivity if their approved application contains new clinical investigations
(other than bioavailability) that are essential to the approval and were
conducted by or for the applicant. If the FDA grants such exclusivity, the FDA
will not approve another company's 505(b)(2) application (paper NDA) or
abbreviated NDA ("ANDA" or generic drug application) during that period. The
FDA may deny an NDA if applicable regulatory criteria are not satisfied or may
require additional testing or information with respect to the investigational
drug. Even if initial FDA approval is obtained, further studies, including
post-market studies, may be required in order to provide additional data on
safety and will be required in order to gain approval for the use of a product
as a treatment for clinical indications other than those for which the product
was initially tested. The FDA will also require post-market reporting and may
require surveillance programs to monitor the side effects of the drug. Results
of post-marketing programs may limit or expand the further marketing of the
drug. Further, if there are any modifications to the drug, including changes
in indication, manufacturing process or labeling, an NDA supplement may be
required to be submitted to the FDA. Further new scientific data or analyses
developed after approval may form the basis for the FDA to withdraw the NDA.
   
  Among the other requirements for drug product approval is the requirement
that the prospective manufacturer conform to the FDA's cGMP regulations.
Manufacturers also must continue to expend time, money and effort in product,
recordkeeping and quality control to assure that the product meets applicable
specifications and other requirements. The manufacturer also has obligations
to report postmarketing adverse drug experiences to the FDA. The FDA
periodically inspects manufacturing facilities in the United States to assure
compliance with applicable cGMP and other regulatory requirements. Failure of
the Company (or prospective manufacturer) to comply with cGMP regulations or
other FDA regulatory requirements could have a material adverse effect on the
Company and result in one or more regulatory actions affecting either the
product, the Company and its officials, or both.     
 
                                      42
<PAGE>
 
  The Company (or prospective manufacturer) also may be subject to certain
user fees that the FDA is authorized to collect under the Prescription Drug
User Fees Act of 1992 for certain drugs. User fees also pertain to the
establishments where the products are made and to the marketed prescription
drug products.
 
  Completing the multitude of steps necessary before marketing can begin
requires the expenditure of considerable resources and can consume a long
period of time. Delay or failure in obtaining the required approvals,
clearances, permits or inclusions by the Company, its collaborative partners
or its licensees would have an adverse effect on the ability of the Company to
generate sales or royalty revenue. In addition, the impact of new or changed
laws or regulations cannot be predicted.
 
  There can be no assurance that the regulatory framework described above will
not change or that additional regulations will not arise that may affect
approval of or delay an IND or an NDA. In addition, there can be no assurance
that there will not be a change in currently accepted scientific standards
that may affect the ultimate approval of such products. Moreover, because the
Company's present collaborative partners are, and it is expected that the
Company's future collaborative partners may be, primarily responsible for pre-
clinical and clinical trials, regulatory approvals, manufacturing and
commercialization of drugs, the ability to obtain and the timing of regulatory
approvals are not within the control of the Company. Should the collaborative
partners develop regulatory problems, for example, cGMP violations, such
problems may adversely impact upon the Company's resources.
 
  Prior to the commencement of marketing a product in other countries,
approval by the regulatory agencies in such countries is required, whether or
not FDA approval has been obtained for such product. The requirements
governing the conduct of clinical trials and product approvals vary widely
from country to country, and the time required for approval may be longer or
shorter than the time required for FDA approval. Although there are some
procedures for unified filings for certain European countries, in general,
each country has its own procedures and requirements.
 
  The Company is also subject to regulation under other federal laws and
regulation under state and local laws, including laws relating to occupational
safety, laboratory practices, the use, handling and disposition of radioactive
materials, environmental protection and hazardous substance control. Although
the Company believes that its safety procedures for handling and disposing of
radioactive compounds and other hazardous materials used in its research and
development activities comply with the standards prescribed by federal, state
and local regulations, the risk of accidental contamination or injury from
these materials cannot be completely eliminated. In the event of any such
accident, the Company could be held liable for any damages that result and any
such liability could exceed the resources of the Company.
 
COMPETITION
 
  The biotechnology and pharmaceutical industries are intensely competitive
and subject to rapid and significant technological change. Competitors of the
Company in the United States and elsewhere are numerous and include, among
others, major, multinational pharmaceutical and chemical companies,
specialized biotechnology firms and universities and other research
institutions. Many of these competitors employ greater financial and other
resources, including larger research and development staffs and more effective
marketing and manufacturing organizations, than the Company or its
collaborative partners. Acquisitions of competing companies and potential
competitors by large pharmaceutical companies or others could enhance
financial, marketing and other resources available to such competitors. As a
result of academic and government institutions becoming increasingly aware of
the commercial value of their research findings, such institutions are more
likely to enter into exclusive licensing agreements with commercial
enterprises, including competitors of the Company, to market commercial
products. There can be no assurance that the Company's competitors will not
succeed in developing technologies and drugs that are more effective or less
costly than any which are being developed by the Company or which would render
the Company's technology and future drugs obsolete and noncompetitive.
 
                                      43
<PAGE>
 
  In addition, some of the Company's competitors have greater experience than
the Company in conducting pre-clinical and clinical trials and obtaining FDA
and other regulatory approvals. Accordingly, the Company's competitors may
succeed in obtaining FDA or other regulatory approvals for drug candidates
more rapidly than the Company. Companies that complete clinical trials, obtain
required regulatory agency approvals and commence commercial sale of their
drugs before their competitors may achieve a significant competitive
advantage, including certain patent and FDA marketing exclusivity rights that
would delay the Company's ability to market certain products. There can be no
assurance that drugs resulting from the Company's research and development
efforts, or from the joint efforts of the Company and its collaborative
partners, will be able to compete successfully with competitors' existing
products or products under development or that they will obtain regulatory
approval in the United States or elsewhere.
 
EMPLOYEES
   
  As of September 16, 1996, the Company had 53 full-time employees, 45 of whom
were engaged in research and development and eight of whom were engaged in
management, administration and finance. Doctorates are held by 24 of the
Company's employees. Each of the Company's employees has signed an agreement
which prohibits the disclosure of confidential information to anyone outside
the Company and requires disclosure and assignment to the Company of ideas,
developments, discoveries and inventions made by the employee.     
 
  The Company's employees are not covered by a collective bargaining
agreement. The Company has never experienced an employment-related work
stoppage and considers its employee relations to be good.
 
PROPERTIES
 
  The Company's headquarters and research and development facilities are
located in a 24,000 square foot facility in Cambridge, Massachusetts at 24
Emily Street. The Company believes that this space will be adequate for its
research and drug development activities for at least the next two years.
 
SCIENTIFIC ADVISORY BOARD
 
  The Company has established a Scientific Advisory Board consisting of ten
members (including Dr. Schimmel and Dr. Rebek, two of the Company's founders
and directors) with experience in infectious disease, cell and molecular
biology, genetics, enzymology, bacterial pathogenesis, and medicinal and
combinatorial chemistry. The Scientific Advisory Board meets as a group once
per year and members are available individually on an ongoing basis. The
Scientific Advisory Board recommends and reviews with the Company novel
approaches to drug discovery and development. For biographical information
regarding Dr. Schimmel and Dr. Rebek, see "Management."
 
  All of the Company's Scientific Advisory Board members have signed
consulting agreements with the Company and have either purchased shares of
Common Stock or been granted options to purchase Common Stock.
 
  The members of Cubist's Scientific Advisory Board are:
 
  Lan Bo Chen, Ph.D. is a Professor of Pathology at Harvard Medical School and
the Dana-Farber Cancer Institute. He is an expert in cell biology, immunology
and cancer. He consults with the Company on high-throughput screening and cell
culture. Dr. Chen received his B.S. in Chemistry from National Taiwan
University and his Ph.D. in Cell Biology from the Massachusetts Institute of
Technology.
 
  R. Alan B. Ezekowitz, M.D., Ph.D. is Chief of Pediatrics at Massachusetts
General Hospital and Professor of Pediatrics at Harvard Medical School. He is
an expert in molecular biology and cell biology of macrophages and pattern
recognition of foreign molecules in host defenses. He consults with the
Company on opportunistic infections, particularly Pneumocystis carinii in
immunocompromised patients. Dr. Ezekowitz
 
                                      44
<PAGE>
 
received his M.B.Ch.B. (equivalent to an M.D.) from the University of Cape
Town, Republic of South Africa and received his Ph.D. in Immunology from the
University of Oxford.
 
  David C. Hooper, M.D. is an Associate Physician and Associate Chief of the
Infection Control Unit at Massachusetts General Hospital as well as an
Associate Professor of Medicine at Harvard Medical School. Dr. Hooper is an
expert in the mechanism of action and resistance in fluoroquinolones. He is a
clinical investigator in infectious disease and consults with the Company on
infectious disease clinical problems, antiinfective resistance and mechanisms
of action of antiinfective drugs. Dr. Hooper received his B.A. in Microbiology
from the University of Texas, Austin and his M.D. from Washington University
School of Medicine.
 
  K.C. Nicolaou, Ph.D. is Chairman of the Department of Chemistry and a
Professor of Chemistry at The Scripps Research Institute. Dr. Nicolaou is an
expert on the total synthesis of biologically active natural products such as
macrolides, ionophores, eiconsanoids, saccharides, glycoconjugates and other
plant, bacterial and marine products. He consults with the Company on organic
and natural product synthesis. Dr. Nicolaou received his B.Sc. and Ph.D. in
Chemistry from the University of London.
 
  Joanne Stubbe, Ph.D. is a Professor of Biology and Chemistry at the
Massachusetts Institute of Technology. Dr. Stubbe's expertise is in the
elucidation of enzyme mechanisms, the design of suicide inhibitors, the
mechanism of cleavage of DNA by antitumor agents, purine biosynthesis and the
mechanism of DNA repair enzymes. She consults with the Company on enzyme
kinetics and assay development. Dr. Stubbe received her B.A. in Chemistry from
the University of Pennsylvania and her Ph.D. in Organic Chemistry from the
University of California, Berkeley.
 
  Jack Szostak, Ph.D. is a Professor of Genetics at Harvard Medical School and
a Molecular Biologist at Massachusetts General Hospital. He is an expert in
molecular biology and is known for his work on ribozymes. He consults with the
Company on molecular biology and assay development. Dr. Szostak received his
B.Sc. in Cell Biology from McGill University and his Ph.D. in Biochemistry
from Cornell University.
 
  Andrew Wright, Ph.D. is a Professor of Molecular Biology and Microbiology at
Tufts University School of Medicine. Dr. Wright is an expert on the regulation
of transcription in bacteria and the study of pathogenic mechanisms in
Haemophilus influenzae and Helicobacter pylori. He consults with the Company
on molecular biology and assay development. Dr. Wright received his B.S. in
Chemistry and his Ph.D. in Biochemistry from the University of Edinburgh,
Scotland.
 
  Richard Young, Ph.D. is a Member of the Whitehead Institute for Biomedical
Research and a Professor of Biology at the Massachusetts Institute of
Technology. Dr. Young is a molecular geneticist with expertise in gene
expression, bacterial pathogenesis and vaccine development. He consults with
the Company on selection of pathogenic organisms, molecular biology and assay
development. Dr. Young received his B.S. in Biology from Indiana University
and his Ph.D. in Molecular Biophysics and Biochemistry from Yale University.
 
LEGAL PROCEEDINGS
 
  The Company is not a party to any material legal proceedings.
 
                                      45
<PAGE>
 
                                  MANAGEMENT
 
EXECUTIVE OFFICERS, KEY EMPLOYEES AND DIRECTORS
 
  The executive officers, key employees and directors of the Company are as
follows:
 
<TABLE>   
<CAPTION>
 NAME                                        AGE   POSITION
 ----                                        ---   --------
 <C>                                         <S>   <C>
 Scott M. Rocklage, Ph.D.(5)................ 42    President, Chief Executive Officer and Director
 Francis P. Tally, M.D. .................... 56    Vice President of Research and Development
 Arthur F. Kluge, Ph.D. .................... 52    Vice President of Chemistry
 Neal M. Farber, Ph.D. ..................... 45    Vice President of Corporate Development
 Thomas A. Shea............................. 36    Director of Finance & Administration, Treasurer
 Philip A. Wendler, Ph.D. .................. 43    Director of Pharmacology
 Susan K. Whoriskey, Ph.D. ................. 37    Director of Molecular Biology
 John K. Clarke(2)(5)....................... 43    Chairman of the Board of Directors
 Paul R. Schimmel, Ph.D.(5)................. 56    Director
 Julius Rebek, Jr., Ph.D.(4)................ 52    Director
 Ellen M. Feeney(1)(2)(3)................... 36    Director
 Terrance G. McGuire(1)(3).................. 40    Director
 Barry Bloom, Ph.D.(1)(4)................... 68    Director
 George Conrades(2)(4)...................... 55    Director
</TABLE>    
- --------
(1) Member of Audit Committee.
(2) Member of Compensation Committee.
(3) Class I Director--term expires in 1997.
(4) Class II Director--term expires in 1998.
(5) Class III Director--term expires in 1999.
 
  Dr. Rocklage has served as President and Chief Executive Officer and as a
member of the Board of Directors of the Company since July 1994. From 1990 to
1994, Dr. Rocklage served as President and Chief Executive Officer of Nycomed
Salutar, Inc., a diagnostic imaging company. From 1992 to 1994, he also served
as President and Chief Executive Officer and Chairman of Nycomed
Interventional, Inc., a medical device company. From 1986 to 1990, he served
in various positions at Salutar, Inc., a diagnostic imaging company and was
responsible for designing and implementing research and development programs
that resulted in three drug products in human clinical trials, including the
approved drug Omniscan. Dr. Rocklage received his B.S. in Chemistry from the
University of California, Berkeley and his Ph.D. in Chemistry from the
Massachusetts Institute of Technology.
 
  Dr. Tally has served as Vice President of Research and Development since
March 1995. From 1986 to 1995, he served as Executive Director of Infectious
Disease, Molecular Biology and Natural Products Research at the Lederle
Laboratories of American Cyanamid/American Home Products, where he was
responsible for worldwide clinical studies for piperacillin/tazobactam which
was registered for sales in Europe in 1992, approved by the FDA in 1993 and
marketed as Zosyn. From 1975 to 1986, he served as Senior Physician in
Infectious Disease at the New England Medical Center and Associate Professor
of Medicine at Tufts Medical Center. Dr. Tally received his A.B. in Biology
from Providence College and his M.D. from George Washington University School
of Medicine.
 
  Dr. Kluge has served as Vice President of Chemistry since October 1995. From
1973 to 1995, Dr. Kluge served in various positions at Syntex Corporation
(which later became Roche Bioscience following the acquisition of Syntex by
Hoffmann-La Roche Inc.), including Vice President and Director, Institute of
Organic Chemistry, where he invented two currently marketed pharmaceutical
products: laidlomycin propionate and ketorolac. Dr. Kluge received his B.A. in
Chemistry from Park College, his M.S. and Ph.D. in Chemistry from the
University of Massachusetts and his M.B.A. from the University of Santa Clara.
 
  Dr. Farber has served as Vice President of Corporate Development since April
1996. From 1993 to 1995, Dr. Farber served as Director of Business Development
at T Cell Sciences, Inc., a biotechnology company.
 
                                      46
<PAGE>
 
From 1982 to 1993, Dr. Farber served in various positions at Biogen, Inc., a
biotechnology company. Dr. Farber received his B.Sc. in Chemistry and
Biochemistry from the Hebrew University, Israel and his Ph.D. in Biochemistry
from Columbia University.
 
  Mr. Shea has served as Treasurer and Chief Accounting Officer since June
1996 and has served as Director of Finance and Administration since September
1993. From 1987 to 1993, he served as Manager of Accounting/MIS and Budget and
Financial Analyst at ImmuLogic Pharmaceutical Corporation, a biotechnology
company. Mr. Shea received his B.S. in Accounting/Law from Babson College.
 
  Dr. Wendler has served as Director of Pharmacology since August 1994. From
1988 to 1994, he served in various scientific positions at Sandoz Chemicals
Biotech Research Corporation. Dr. Wendler received his B.S. in Biochemistry
from Trinity College and his Ph.D. in Biological Science (Biochemistry) from
the University of Rhode Island.
 
  Dr. Whoriskey has served as Director of Molecular Biology since January
1996. From 1993 to 1995, she served as a Research Scientist and then Group
Leader of Molecular Biology at the Company. From 1989 to 1993, she was a
Research Fellow in the Department of Genetics at Harvard Medical School.
Dr. Whoriskey received her B.S. in Microbiology from the University of
Massachusetts, Amherst and her Ph.D. from the Molecular Biology Institute at
the University of California, Los Angeles.
 
  Mr. Clarke is a founder of the Company and has served as Chairman of the
Board of Directors since its incorporation. From May 1992 to June 1994, Mr.
Clarke served as acting President and Chief Executive Officer of the Company.
Since 1982, he has been a general partner of DSV Management in Princeton, New
Jersey, the general partner of DSV Partners IV ("DSV"). He is a founder and
director of Alkermes, Inc. and DNX, Inc., biotechnology companies. Mr. Clarke
received his B.A. in Biology and Economics from Harvard College and his M.B.A.
from The Wharton School of the University of Pennsylvania.
 
  Dr. Schimmel is a scientific founder of the Company and has served as a
director of the Company since its incorporation. Since 1967, he has served as
a Professor of Biochemistry and Biophysics at the Massachusetts Institute of
Technology and since 1992, he has been the John D. and Catherine T. MacArthur
Professor of Biochemistry and Biophysics. Dr. Schimmel is an expert in
molecular biology, protein translation and aminoacyl-tRNA synthetases. He is a
member of the National Academy of Sciences and the American Academy of Arts
and Sciences. Dr. Schimmel was a founder and is a director of Repligen
Corporation and Alkermes, Inc., biotechnology companies. Dr. Schimmel received
his A.B. in Pre-Medicine from Ohio Wesleyan University and his Ph.D. in
Biochemistry from the Massachusetts Institute of Technology.
 
  Dr. Rebek is a scientific founder of the Company and has served as a
director of the Company since its incorporation. Since July 1996, he has
served as the Director of the Institute for Chemical Biology at The Scripps
Research Institute. From 1989 to June 1996, Dr. Rebek served as Professor of
Chemistry at the Massachusetts Institute of Technology, and from 1991 to June
1996, he served as the Camille Dreyfus Professor of Chemistry. Dr. Rebek is an
expert in synthetic organic chemistry, molecular recognition and combinatorial
chemistry. He is a member of the National Academy of Sciences and the American
Academy of Arts and Sciences. Dr. Rebek serves on the Scientific Advisory
Board of Procept, Inc., a biotechnology company. He is also a Founding Member
of the Scientific Advisory Board of Darwin Molecular, Inc., a genomics
company. Dr. Rebek received his B.S. in Chemistry from the University of
Kansas and his Ph.D. in Chemistry from the Massachusetts Institute of
Technology.
 
  Ms. Feeney has served as a director of the Company since September 1993.
Since 1991, she has served as a principal of Weiss, Peck & Greer, L.L.C., and
since 1989, she has been a General Partner of WPG Venture Partners II, L.P.,
the general partner of WPG Enterprise Fund, L.P. ("WPG Enterprise"), Weiss,
Peck & Greer Venture Associates II, L.P. ("WPG Venture") and WPG Venture
Advisers, L.P., the adviser of Weiss, Peck & Greer Venture Associates II
(Overseas), L.P. ("WPG Overseas"). Ms. Feeney is a director of Heartstream,
Inc., a medical device company, and several private health care companies. Ms.
Feeney received her B.S. in Biology and Philosophy from Duke University and
her M.S. in Human Genetics from the University of California, Davis.
 
 
                                      47
<PAGE>
 
  Mr. McGuire has served as a director of the Company since September 1993.
Since 1995, he has been a Founding General Partner of Polaris Venture
Partners, and since 1989, has served as a general partner of Beta Partners
Limited Partnership, each of which is a venture capital firm. Since 1992, he
has served as a general partner of Alta V Management Partners L.P., which is
the general partner of Alta V Limited Partnership ("Alta"), a fund associated
with Burr, Egan, Deleage & Co. He is a director of Integ, Inc., a diagnostic
company, and several private health care companies. Mr. McGuire received his
B.S. in Physics and Economics from Hobart College, his M.S. in Engineering
from Dartmouth College and his M.B.A. from the Harvard Business School.
 
  Dr. Bloom has served as a director of the Company since September 1993. Dr.
Bloom has more than 40 years experience in the pharmaceutical industry. From
1952 to 1993, Dr. Bloom served in various positions at Pfizer Inc, including
Executive Vice President of Research & Development. He is a director of Vertex
Pharmaceuticals, Inc. and Neurogen Corp., biotechnology companies, Southern
New England Telecommunications Corporation, Catalytica Fine Chemicals, Inc., a
chemical manufacturer and supplier, and Incyte Pharmaceuticals, Inc., a
genomics company. Dr. Bloom received his S.B. in Chemistry and his Ph.D. in
Organic Chemistry from the Massachusetts Institute of Technology.
 
  Mr. Conrades has served as a director of the Company since June 1996. Since
1994, he has served as President and Chief Executive Officer of BBN
corporation, a corporation providing Internet services and research and
development and he has served as Chairman since 1995. From 1961 to 1992, Mr.
Conrades served in various positions at IBM, including Senior Vice President,
Corporate Marketing and Services. He is a member of the Board of Directors of
Westinghouse, Inc. and CRA Managed Care, Inc. Mr. Conrades received his B.A.
in Physics and Mathematics from Ohio Wesleyan University and his M.B.A. from
the University of Chicago.
 
BOARD OF DIRECTORS
 
  Effective upon the consummation of this Offering, the Company's Board of
Directors will be divided into three classes, with one class of directors
elected each year at the annual meeting of stockholders for a three-year term
of office. All directors of one class hold their positions until the annual
meeting of stockholders at which their respective successors are elected and
qualified. Ms. Feeney and Mr. McGuire serve in the class whose term expires in
1997; Dr. Bloom, Mr. Conrades and Dr. Rebek serve in the class whose term
expires in 1998; and Mr. Clarke, Dr. Rocklage and Dr. Schimmel serve in the
class whose term expires in 1999. Executive officers of the Company are
elected annually by the Board of Directors and serve at the discretion of the
Board of Directors or until their successors are duly elected and qualified.
 
  The Board of Directors has appointed an Audit Committee and a Compensation
Committee. The Audit Committee reviews the scope and results of the annual
audit of the Company's financial statements conducted by the Company's
independent accountants, the scope of other services provided by the Company's
independent accountants, proposed changes in the Company's financial and
accounting standards and principles, and the Company's policies and procedures
with respect to its internal accounting, auditing and financial controls, and
makes recommendations to the Board of Directors on the engagement of the
independent accountants, as well as other matters which may come before it or
as directed by the Board of Directors. The Compensation Committee administers
the Company's compensation programs, including the Plan, and performs such
other duties as may from time to time be determined by the Board of Directors.
 
DIRECTOR COMPENSATION
 
  In 1995, the Company paid $6,000 to Dr. Bloom in connection with attendance
at meetings of the Board of Directors. No other director has received
compensation for his or her service on the Board of Directors or any committee
thereof, except that in May and June of 1996, the Company has granted to each
non-employee director a nonstatutory stock option exercisable for 7,142 shares
at an exercise price of $1.96 and $5.95, respectively. See "Certain
Transactions."
 
  Following this Offering, Dr. Bloom and Mr. Conrades will receive a fee of
$1,000 for each Board meeting attended and will be reimbursed for expenses
incurred in connection with their attendance. In addition, upon first joining
the Board each director who is not an officer or employee of the Company will
be granted
 
                                      48
<PAGE>
 
   
automatically a stock option exercisable for 7,000 shares of Common Stock at
fair market value, and each time that he or she is serving as a director on
the business day immediately following an annual meeting of stockholders, such
director will be automatically granted on such business day a stock option
exercisable for 700 shares of Common Stock at fair market value. See "Amended
and Restated 1993 Stock Option Plan."     
 
EXECUTIVE COMPENSATION
 
  The following table sets forth certain information with respect to the
annual and long-term compensation paid by the Company during the fiscal year
ended December 31, 1995 to the Chief Executive Officer and the other executive
officers of the Company (the "Named Executive Officers") whose 1995
compensation exceeded $100,000:
 
                          SUMMARY COMPENSATION TABLE
 
<TABLE>
<CAPTION>
                                                                    LONG-TERM COMPENSATION
                                   ANNUAL COMPENSATION                      AWARDS
                         ---------------------------------------- --------------------------
                                                                  SECURITIES
NAME AND                                          OTHER ANNUAL    UNDERLYING    ALL OTHER
PRINCIPAL POSITION       SALARY($)(1) BONUS($) COMPENSATION($)(2) OPTIONS(#) COMPENSATION($)
- ------------------       ------------ -------- ------------------ ---------- ---------------
<S>                      <C>          <C>      <C>                <C>        <C>
Scott M. Rocklage.......   $180,434   $50,000        $6,072         14,285       $23,587(3)
 President, Chief
  Executive Officer and
 Director
Francis P. Tally........    165,280       --          8,258            --            --
 Vice President of
  Research and
 Development
Nancy Gray(4)...........    113,228    11,440           --           5,714           --
 Vice President of
  Corporate Development
</TABLE>
- -------
(1) Salary includes amounts, if any, deferred pursuant to the Company's 401(k)
    Plan.
(2) Other Annual Compensation consists of long-term disability insurance
    premiums paid by the Company on behalf of the Named Executive Officer.
(3) The Company forgave $23,587 of principal and accrued interest owed by Dr.
    Rocklage under certain promissory notes. See "Certain Transactions."
(4) Dr. Gray resigned from the Company in February 1996, at which time options
    for 4,285 shares were terminated and restricted stock totaling 17,857
    shares were repurchased by the Company.
 
  The following table sets forth certain information with respect to grants of
stock options under the Plan to the Named Executive Officers during the year
ended December 31, 1995.
 
               OPTION GRANTS DURING YEAR ENDED DECEMBER 31, 1995
<TABLE>
<CAPTION>
                                                                            POTENTIAL REALIZABLE
                                                                              VALUE AT ASSUMED
                                                                              ANNUAL RATES OF
                                                                                STOCK PRICE
                                                                              APPRECIATION FOR
                                         INDIVIDUAL GRANTS                   OPTION TERM($)(2)
                         -------------------------------------------------- --------------------
                                         PERCENT OF
                            NUMBER          TOTAL
                         OF SECURITIES OPTIONS GRANTED EXERCISE
                          UNDERLYING   TO EMPLOYEES IN PRICE PER EXPIRATION
NAME                     OPTIONS(#)(1) FISCAL YEAR(%)  SHARE($)     DATE       5%        10%
- ----                     ------------- --------------- --------- ---------- --------- ----------
<S>                      <C>           <C>             <C>       <C>        <C>       <C>
Scott M. Rocklage.......    14,285          6.05%        $0.42    10/18/05  $   9,773 $   15,562
Francis P. Tally........       --            --            --        --           --         --
Nancy Gray(3)...........     5,714          2.42          0.35       --         4,561      7,262
</TABLE>
- -------
(1) Represents incentive stock options granted under the Plan to Dr. Rocklage
    on October 18, 1995 and to Dr. Gray on January 1, 1995. Each option is
    exercisable in 16 equal quarterly installments, and has a maximum term of
    10 years from the date of grant, subject to earlier termination in the
    event of the optionee's cessation of service with the Company. The options
    are exercisable during the holder's lifetime only by the holder and they
    are exercisable by the holder only while the holder is an employee of the
    Company and for certain limited periods of time thereafter in the event of
    termination of employment.
(2) Amounts represent hypothetical gains that could be achieved for the
    respective options if exercised at the end of the option term. These gains
    are based upon assumed appreciation rates of 5% and 10% in the fair market
    value of shares of Common Stock from the fair market value on the date of
    grant, which rates are set by the Securities and Exchange Commission and
    compounded annually from the date the respective options were granted to
    their expiration date. The gains shown are net of option exercise prices,
    but do not include deductions for taxes or other expenses associated with
    the exercises. Actual gains, if any, are dependent on the performance of
    the Common Stock and the date on which the option is exercised. There can
    be no assurance that the amounts reflected will be achieved or will
    otherwise be indicative of the actual amounts received, if any.
(3) Dr. Gray resigned from the Company in February 1996, at which time options
    for 4,285 shares were terminated.
 
                                      49
<PAGE>
 
  The following table sets forth information with respect to (i) the number of
unexercised options held by the Named Executive Officers as of December 31,
1995 and (ii) the value of unexercised in-the-money options (options for which
the fair market value of the Common Stock exceeds the exercise price) as of
December 31, 1995. In fiscal 1995, there were no option exercises by the Named
Executive Officers.
 
         AGGREGATED OPTION VALUES IN THE YEAR ENDED DECEMBER 31, 1995
 
<TABLE>
<CAPTION>
                              NUMBER OF SECURITIES                  VALUE OF UNEXERCISED
                             UNDERLYING UNEXERCISED                 IN-THE-MONEY OPTIONS
                         OPTIONS AT DECEMBER 31, 1995(#)         AT DECEMBER 31, 1995 ($)(1)
                         -------------------------------         ---------------------------
NAME                      EXERCISABLE        UNEXERCISABLE       EXERCISABLE      UNEXERCISABLE
- ----                     ---------------    ----------------     ------------     --------------
<S>                             <C>               <C>                  <C>            <C>
Scott M. Rocklage.......             0              14,285               0             $6,000
Francis P. Tally........            --                  --              --                 --
Nancy Gray (2)..........         1,429               4,285              700             2,100
</TABLE>
- --------
(1) Based on the fair market value of the Common Stock as of December 15, 1995
    of $0.84 per share, as determined by the Company's Board of Directors,
    less the aggregate exercise price.
(2) Dr. Gray resigned from the Company in February 1996, at which time options
    for 4,285 shares were terminated.
 
AMENDED AND RESTATED 1993 STOCK OPTION PLAN
 
  The Plan provides for grants of stock options intended to qualify for
preferential tax treatment (the "Incentive Stock Options") under Section 422
of the Internal Revenue Code of 1986, as amended (the "Code"), and
nonstatutory stock options that do not qualify for such treatment. All
employees of the Company are eligible for stock options under the Plan in
amounts and at prices determined by the Compensation Committee, provided that,
in the case of Incentive Stock Options, the price will not be less than 100%
of the fair market value of the Common Stock on the date of grant, or not less
than 110% of the fair market value of the Stock on the grant date if the
optionee owns, directly or indirectly, more than 10% of the total combined
voting power of all classes of stock.
   
  Each director who is not an officer or employee of the Company (a "Non-
Employee Director") who is first elected to the Board of Directors during the
term of the Plan will receive, on the director's election date, an option to
purchase 7,000 shares of Common Stock. In addition, each time that a Non-
Employee Director is serving as a director on the business day immediately
following an annual meeting of stockholders, he or she will be automatically
granted on such business day a stock option exercisable for 700 shares of
Common Stock at fair market value, which will become exercisable in four equal
installments on the last day of each subsequent fiscal quarter if the optionee
remains a director on that date.     
 
  The Plan will be administered by the Compensation Committee. The
Compensation Committee will select participants (other than for automatic
grants to Non-Employee Directors as set forth in the Plan) and, in a manner
consistent with the terms of the Plan, determine the number and duration of
the options to be granted and the terms and conditions of the option
agreements. The Compensation Committee has the right to alter, amend or revoke
the Plan.
 
  The Plan provides that each outstanding option will immediately become fully
exercisable upon a "Change in Corporate Control" of the Company, as defined in
the Plan. A "Change in Corporate Control" includes the acquisition by any
third party (as hereinafter defined), directly or indirectly, of more than 80%
of the Common Stock outstanding at the time, without the prior approval of the
Company's Board of Directors. A "third party" for purposes of the foregoing
means any person other than the Company or a subsidiary or employee benefit
plan or trust maintained by the Company or any of its subsidiaries together
with any of such person's "affiliates" and "associates" as defined in Rule
12b-2 under the Securities Exchange Act of 1934, as amended.
 
  A total of 1,500,000 shares of Common Stock of the Company is reserved for
issuance under the Plan. The maximum number of shares will increase, effective
as of January 1, 1998 and each January 1 thereafter during the term of the
Plan, by an additional number of shares of Common Stock equal to 15% of the
excess, if any, of (i) the total number of shares of Common Stock and Common
Stock equivalents issued and
 
                                      50
<PAGE>
 
outstanding as of the close of business on December 31 of the preceding year
over (ii) the total number of shares of Common Stock and Common Stock
equivalents issued and outstanding as of the close of business
   
on December 31 of the year prior to such preceding year. The maximum number of
shares that may be subject to incentive stock options granted under the Plan
is 3,000,000 shares, and the maximum number of shares that may be subject to
stock options granted to any person (including Non-Employee Directors) under
the Plan in a given year is 500,000 shares.     
   
  Incentive Stock Options granted under the Plan are not transferable except
by will or the laws of descent and distribution, and may be exercised during
the life of the optionee only by the optionee. Nonstatutory stock options
granted under the Plan are not transferable except by will or the laws of
descent and distribution and except that nonstatutory stock options may be
transferred if and to the extent authorized by the Compensation Committee.
    
401(K) PLAN
 
  The Company has implemented a retirement savings plan (the "401(k) Plan"),
which covers all full-time employees. Pursuant to the 401(k) Plan, an employee
may elect to reduce his or her current compensation by up to 15% (subject to
certain overall dollar limits) and have the amount of such reduction
contributed to the 401(k) Plan. The 401(k) Plan allows employees with six
months continuous service to make certain tax-deferred voluntary
contributions, which the Company generally intends to match with a 1.5%
contribution, but in any event not to exceed $500. The 401(k) Plan is intended
to qualify under Section 401 of the Code, so that contributions by employees,
and earned income thereon, are not taxable to employees until withdrawn from
the 401(k) Plan. The administrator of the 401(k) Plan will invest each
employee's account at the direction of each such employee, who can choose
among certain investment alternatives provided.
 
EMPLOYMENT AGREEMENT
 
  Dr. Rocklage, the Company's President and Chief Executive Officer, is
employed pursuant to an employment agreement with the Company, dated June 20,
1994 (the "Employment Agreement"). Under the terms of the Employment
Agreement, Dr. Rocklage will receive an annual base salary in 1996 of $185,000
and is entitled to a performance bonus of up to $50,000, subject to review by
the Company's Board of Directors, upon the Company's achievement of certain
milestones for such year that have been mutually agreed upon by Dr. Rocklage
and the Board of Directors prior to the commencement of such fiscal year.
Pursuant to the terms of the Employment Agreement, on July 21, 1994 the
Company granted to Dr. Rocklage a stock option exercisable for 188,121 shares
of the Company's Common Stock at an exercise price of $0.35 per share, and
sold to Dr. Rocklage 263,370 shares of Series B Convertible Preferred Stock
(convertible into 37,624 shares of Common Stock) at a purchase price of $0.50
per share ($3.50 per share on an as-converted basis). To purchase the shares
of Series B Convertible Preferred Stock and to exercise his option, Dr.
Rocklage issued two promissory notes to the Company. See "Certain
Transactions." The Employment Agreement also provides Dr. Rocklage with
medical insurance and other fringe benefits. Dr. Rocklage's employment with
the Company may be terminated by the Company at any time by giving written
notice of termination and may be terminated by Dr. Rocklage at any time upon
thirty days' written notice of termination. Upon any termination by the
Company of Dr. Rocklage's employment without cause, Dr. Rocklage is entitled
to severance pay in an amount equal to three months of his then current annual
base salary.
 
  None of the Company's other executive officers has entered into an
employment agreement with the Company. See "Risk Factors--Dependence on Key
Personnel."
 
COMPENSATION COMMITTEE INTERLOCKS
   
  In 1995, the members of the Compensation Committee of the Board of Directors
were Mr. Clarke, Dr. Schimmel and Dr. Rebek, none of whom is an employee of
the Company. As of July, 1996, the members of the Compensation Committee are
Mr. Clarke, Mr. Conrades and Ms. Feeney, none of whom is an employee of the
Company.     
 
 
                                      51
<PAGE>
 
                             CERTAIN TRANSACTIONS
 
  In August 1993, the Company sold an aggregate of 14,270,000 shares of its
Series B Convertible Preferred Stock (convertible into 2,038,571 shares of
Common Stock), at a purchase price of $0.50 per share ($3.50 per share on an
as-converted basis) to a group of stockholders, including DSV, Alta, WPG
Enterprise, WPG Venture, and Interwest Partners V, L.P. ("Interwest"), Dr.
Schimmel, Dr. Rebek, and the Julius Rebek, Jr. Retirement Plan. Mr. Clarke, a
director of the Company, is a general partner of DSV Management, the general
partner of DSV. Ms. Feeney, a director of the Company, is a general partner of
WPG Venture Partners II, L.P., the general partner of WPG Enterprise and WPG
Venture. Mr. McGuire, a director of the Company, is a general partner of Alta
V Management Partners, L.P., the general partner of Alta. Dr. Schimmel and Dr.
Rebek are directors of the Company. The Julius Rebek, Jr. Retirement Plan is
an affiliate of Dr. Rebek.
 
  In August 1993, Dr. Schimmel executed a promissory note to the Company in
the amount of $250,000 with a 4% annual interest rate in connection with his
purchase of Series B Convertible Preferred Stock. This note has been paid in
full.
 
  In June 1994, the Company entered into an Employment Agreement with Dr.
Rocklage, President, Chief Executive Officer and a director of the Company.
See "Management--Employment Agreement." In consideration for the performance
of services by Dr. Rocklage under the Employment Agreement, the Company
granted to Dr. Rocklage an incentive stock option to purchase 188,121 shares
of Common Stock, at a purchase price of $0.35, the fair market value of the
Common Stock on the date of grant. Dr. Rocklage purchased 263,370 shares of
Series B Convertible Preferred Stock (convertible into 37,624 shares of Common
Stock), at a purchase price of $0.50 per share ($3.50 per share on an as-
converted basis). In July 1994, Dr. Rocklage executed a promissory note to the
Company in the amount of $131,685 with a 4% annual interest rate to purchase
his shares of Series B Convertible Preferred Stock. This note is secured by
263,370 shares of Series B Convertible Preferred Stock (convertible into
37,624 shares of Common Stock). In November 1994, Dr. Rocklage executed a
promissory note to the Company in the amount of $65,842 with a 4% annual
interest rate in connection with the exercise of his stock option agreement.
One-third of the principal and interest on the promissory note has been
forgiven and the remainder will be forgiven in equal installments on November
28, 1996 and November 28, 1997.
 
  In December 1994, the Company consummated a financing in which it issued
Convertible Demand Promissory Notes in the aggregate principal amount of
$1,000,000 (the "Notes") to a group of existing investors including DSV, Alta,
WPG Enterprise, WPG Venture and Interwest.
 
  In February 1995, the Company sold an aggregate of 9,428,644 shares of its
Series C Convertible Preferred Stock (convertible into 1,346,949 shares of
Common Stock), at a purchase price of $0.60 per share ($4.20 per share on an
as-converted basis) to a group of existing investors, including DSV, Alta, WPG
Enterprise, WPG Venture and Interwest. The purchase price of the Series C
Convertible Preferred Stock was paid in part by the conversion and
cancellation of the Notes (plus accrued interest) previously issued by the
Company to certain investors.
 
  In May 1995, the Company issued a warrant to each of Dr. Schimmel and Dr.
Rebek to purchase 120,000 shares of Series C Convertible Preferred Stock
(convertible into 17,142 shares of Common Stock), at an exercise price of
$0.60 per share ($4.20 per share on an as-converted basis).
 
  In May 1995, the Company sold an aggregate of 5,589,169 shares of its Series
C Convertible Preferred Stock (convertible into 798,452 shares of Common
Stock), at a purchase price of $0.60 per share ($4.20 per share on an as-
converted basis) to a group of new investors, including H&Q Healthcare
Investors, H&Q Life Sciences Investors, and Rovent II Limited Partnership.
 
  In May 1996, the Company granted to certain of its officers stock options
under the Plan exercisable for an aggregate of 126,507 shares of Common Stock
at an exercise price of $1.96 per share, and the Company granted to certain of
its directors stock options exercisable for an aggregate of 42,857 shares of
Common Stock at an exercise price of $1.96 per share.
 
                                      52
<PAGE>
 
   
  In June 1996, the Company sold a total of 2,816,902 shares of Series D
Convertible Preferred Stock (convertible into 402,414 shares of Common Stock),
at a purchase price of $1.42 per share ($9.94 per share on an as-converted
basis), to Bristol-Myers Squibb. In addition, the Company may issue Common
Stock after the closing of this Offering to Bristol-Myers Squibb pursuant to
certain antidilution rights of Bristol-Myers Squibb.     
 
  In June 1996, the Company granted George Conrades, a director of the Company,
a stock option exercisable for 7,142 shares of Common Stock at an exercise
price of $5.95 per share.
 
  For a description of certain transactions and certain employment and other
arrangements between the Company and certain of its directors and executive
officers, see "Management--Director Compensation" and "--Employment
Agreements."
 
  The Company believes that the securities issued in the transactions involving
the Company described above were sold by the Company at their then fair market
value and that the terms of the transactions described above were no less
favorable than the Company could have obtained from unaffiliated third parties.
 
  The Company has adopted a policy, effective following the consummation of
this Offering, that all future transactions between the Company and its
officers, directors and affiliates must (i) be approved by a majority of those
members of the Company's Board of Directors that are not parties, directly or
indirectly through affiliates, to such transactions and (ii) be on terms no
less favorable to the Company than could be obtained from unrelated third
parties.
 
                                       53
<PAGE>
 
                             PRINCIPAL STOCKHOLDERS
 
  The following table sets forth certain information regarding the beneficial
ownership of the Company's Common Stock as of May 31, 1996, giving effect to
the sale of 2,816,902 shares of Series D Convertible Preferred Stock
(convertible into 404,414 shares of Common Stock) to Bristol-Myers Squibb on
June 1996 and the conversion of all outstanding shares of the Company's
Preferred Stock into an aggregate of 5,366,869 shares of Common Stock by (i)
each person known to the Company to be the beneficial owner of more than 5% of
the shares of Common Stock, (ii) each director of the Company, (iii) each of
the Named Executive Officers and (iv) all current directors and executive
officers as a group.
<TABLE>   
<CAPTION>
                                                    SHARES    PERCENT  PERCENT
                                                 BENEFICIALLY  BEFORE   AFTER
NAME AND ADDRESS OF BENEFICIAL OWNER               OWNED(1)   OFFERING OFFERING
- ------------------------------------             ------------ -------- --------
<S>                                              <C>          <C>      <C>
DSV Partners IV(2)..............................  1,643,499    25.77%   19.62%
 221 Nassau Street
 Princeton, NJ 08542
Entities affiliated with
Interwest Management Partners(3)................    789,213    12.37     9.42
 300 Sandhill Road
 Building 3, Suite 255
 Menlo Park, CA 94025-7112
Entities affiliated with
Burr, Egan, Deleage & Co.(4)....................    786,356    12.33     9.39
 One Post Office Square, Suite 3800
 Boston, MA 02109
Entities affiliated with
Weiss, Peck & Greer, L.L.C.(5)..................    667,308    10.46     7.96
 555 California Street, Suite 4760
 San Francisco, CA 94104
Entities affiliated with
H&Q Capital Management(6).......................    428,571     6.72     5.12
 50 Rowes Wharf
 Boston, MA 02110
Bristol-Myers Squibb Company(7).................    402,414     6.31     4.80
 P.O. Box 4000
 Princeton, NJ 08543
Entities affiliated with
Advent International Corporation(8).............    357,142     5.60     4.26
 101 Federal Street
 Boston, MA 02110
Scott M. Rocklage(9)............................    240,302     3.77     2.87
Francis P. Tally................................     92,857     1.46     1.11
Nancy Gray(10)..................................     12,142      *        *
John K. Clarke(11)..............................  1,643,499    25.77    19.62
Paul R. Schimmel(12)............................    302,856     4.74     3.61
Julius Rebek, Jr.(13)...........................    241,000     3.77     2.88
Ellen M. Feeney(14).............................    667,308    10.46     7.96
Terrance G. McGuire(15).........................    778,178    12.20     9.29
Barry Bloom(16).................................      8,928      *        *
George Conrades.................................      *          *        *
All current executive officers and directors as
a group (12 persons)(17)........................  3,988,944    62.54    47.61
</TABLE>    
 
                                       54
<PAGE>
 
- --------
  * Less than 1% of the outstanding shares of Common Stock.
 
 (1) Beneficial ownership is determined in accordance with Rule 13d-3(d)
     promulgated by the Commission under the Securities and Exchange Act of
     1934, as amended. Shares of Common Stock issuable pursuant to options,
     warrants and convertible securities, to the extent such securities are
     currently exercisable or convertible within 60 days of May 31, 1996, are
     treated as outstanding for computing the percentage of the person holding
     such securities but are not treated as outstanding for computing the
     percentage of any other person. Unless otherwise noted, each person or
     group identified possesses sole voting and investment power with respect
     to shares, subject to community property laws where applicable. Shares not
     outstanding but deemed beneficially owned by virtue of the right of a
     person or group to acquire them within 60 days are treated as outstanding
     only for purposes of determining the number of and percent owned by such
     person or group.
 
 (2) DSV Management is the general partner of DSV and as such shares voting and
     investment power with respect to the shares owned by DSV. DSV Management
     may be deemed to beneficially own all of the shares owned by DSV although
     DSV Management disclaims beneficial ownership except to the extent of its
     proportionate partnership interest in DSV. Mr. Clarke is a general partner
     of DSV Management.
   
 (3) Consists of 783,986 shares held by Interwest and 5,227 shares held by
     Interwest Investors V. Interwest Management Partners V is the general
     partner of Interwest and as such Interwest Management Partners V shares
     voting and investment power with respect to the shares owned by Interwest.
     Interwest Management Partners V may be deemed to beneficially own all of
     the shares owned by Interwest although it disclaims beneficial ownership
     except to the extent of its proportionate direct partnership interests in
     Interwest. Mr. Arnold Oronsky, a consultant to the Company, is a general
     partner of Interwest Management Partners V. Mr. Oronsky may be deemed to
     beneficially own all of the shares owned by Interwest Investors V although
     he disclaims beneficial ownership except to the extent of his
     proportionate partnership interest in Interwest Investors V.     
 
 (4) Consists of 778,178 shares held by Alta and 8,178 shares held by Customs
     House Partners. Alta V Management Partners, L.P. is the general partner of
     Alta and as such shares voting and investment power with respect to the
     shares owned by Alta. Alta V Management Partners, L.P. may be deemed to
     beneficially own all of the shares owned by Alta although Alta V
     Management Partners, L.P. disclaims beneficial ownership except to the
     extent of its proportionate partnership interest in Alta. Mr. McGuire is a
     general partner of Alta V Management Partners, L.P. Eileen McCarthy is a
     general partner of Customs House Partners and as such shares voting and
     investment power with respect to the shares owned by Customs House
     Partners. Ms. McCarthy may be deemed to beneficially own all of the shares
     owned by Customs House Partners although Ms. McCarthy disclaims beneficial
     ownership except to the extent of her proportionate partnership interest
     in Customs House Partners.
 
 (5) Consists of 354,741 shares held by WPG Enterprise, 256,380 shares held by
     WPG Venture and 56,187 shares held by WPG Overseas (the "WPG Group"). WPG
     Venture Partners II, L.P. is the general partner of WPG Enterprise and WPG
     Venture and is the investment adviser of WPG Overseas. In such capacities,
     WPG Venture Partners II, L.P. shares voting and investment control with
     respect to the shares owned by the WPG Group. WPG Venture Partners II,
     L.P. may be deemed to beneficially own all of the shares owned by the WPG
     Group although WPG Venture Partners II, L.P. disclaims beneficial
     ownership except to the extent of its proportionate partnership interest
     in each of the partnerships in the WPG Group. Ms. Feeney is a general
     partner of WPG Venture Partners II, L.P.
 
 (6) Consists of 238,095 shares held by H&Q Healthcare Investors and 190,476
     shares held by H&Q Life Sciences Investors. H&Q Capital Management, Inc.
     is the general partner of H&Q Healthcare Investors and H&Q Life Sciences
     Investors and as such H&Q Capital Management, Inc. shares voting and
     investment power with respect to the shares owned by H&Q Healthcare
     Investors and H&Q Life Sciences Investors. H&Q Capital Management, Inc.
     may be deemed to beneficially own all of the shares owned by H&Q
     Healthcare Investors and H&Q Life Sciences Investors although H&Q Capital
     Management, Inc. disclaims beneficial ownership except to the extent of
     its proportionate partnership interest in each of H&Q Healthcare Investors
     and H&Q Life Sciences Investors.
   
 (7) Consists of the purchase in June 1996 of 2,816,902 shares of Series D
     Convertible Preferred Stock and excludes Common Stock that may be issued
     after the closing of this Offering to Bristol-Myers Squibb pursuant to
     certain antidilution rights of Bristol-Myers Squibb.     
 
 (8) Consists of 295,238 shares held by Rovent II Limited Partnership, 59,523
     shares held by Advent Performance Materials Limited Partnership and 2,381
     shares held by Advent International Investors II Limited Partnership.
     Advent International Corporation is the indirect general partner of each
     of Rovent II Limited Partnership, Advent Performance Materials Limited
     Partnership and Advent International Investors II Limited Partnership and
     as such shares voting and investment power with respect to all of such
     shares. Advent International Corporation may be deemed to beneficially own
     all of such shares although it disclaims beneficial ownership except to
     the extent of its indirect proportionate partnership interest in Rovent II
     Limited Partnership, Advent Performance Materials Limited Partnership and
     Advent International Investors II Limited Partnership.
 
 
 (9) Includes 2,678 shares of Common Stock which Dr. Rocklage has the right to
     acquire within 60 days of May 31, 1996 upon exercise of stock options.
 
(10) Dr. Gray resigned from the Company in February 1996.
 
(11) Consists of shares held by DSV. Mr. Clarke, Chairman of the Board of
     Directors of the Company, is a general partner of DSV
 
                                       55
<PAGE>
 
    Management, the general partner of DSV. Mr. Clarke shares voting and
    investment power with respect to the shares owned by DSV. Mr. Clarke may
    be deemed to beneficially own the shares held by DSV although he disclaims
    beneficial ownership except to the extent of his proportionate partnership
    interest therein.
 
(12) Includes 17,142 shares of Common Stock which Dr. Schimmel has the right
     to acquire within 60 days of May 31, 1996 upon the exercise of his stock
     options and warrants.
 
(13) Includes 17,142 shares of Common Stock which Dr. Rebek has the right to
     acquire within 60 days of May 31, 1996 upon the exercise of his stock
     options and warrants and 3,857 shares held by the Julius Rebek, Jr.
     Retirement Plan, over which Dr. Rebek has sole voting power and
     beneficial ownership. Includes shares owned by Dr. Rebek's wife. Dr.
     Rebek disclaims beneficial ownership of all shares owned by his wife.
 
(14) Consists of shares held by the WPG Group. Ms. Feeney, a director of the
     Company, is a general partner of WPG Venture Partners II, L.P., the
     general partner of WPG Enterprise and WPG Venture and the adviser to WPG
     Overseas. Ms. Feeney shares voting and investment control with respect to
     the shares owned by the WPG Group. Ms. Feeney may been deemed to
     beneficially own the shares held by the WPG Group although she disclaims
     beneficial ownership except to the extent of her proportionate
     partnership interest therein.
 
(15) Consists of shares held by Alta. Mr. McGuire, a director of the Company,
     is a general partner of Alta V Management Partners, L.P., the general
     partner of Alta. Mr. McGuire shares voting and investment control with
     respect to the shares owned by Alta. Mr. McGuire may been deemed to
     beneficially own the shares held by Alta although he disclaims beneficial
     ownership except to the extent of his proportionate partnership interest
     therein.
 
(16) Includes 1,785 shares of Common Stock which Dr. Bloom has the right to
     acquire within 60 days of May 31, 1996 upon the exercise of his stock
     options.
   
(17) Includes 52,763 shares of Common Stock which all directors and executive
     officers have the right to acquire within 60 days of May 31, 1996 upon
     the exercise of their stock options.     
 
                                      56
<PAGE>
 
                         DESCRIPTION OF CAPITAL STOCK
   
  Upon the closing of this Offering, the Company will be authorized to issue
25,000,000 shares of Common Stock, $0.001 par value per share, of which
8,373,023 shares will be issued and outstanding, and 5,000,000 shares of
undesignated Preferred Stock, $0.001 par value per share, of which no shares
will be issued and outstanding.     
 
COMMON STOCK
 
  Upon the closing of this Offering, the Company's Restated Certificate of
Incorporation (the "Restated Certificate of Incorporation") will authorize the
issuance of up to 25,000,000 shares of Common Stock, $0.001 par value per
share. Holders of Common Stock are entitled to one vote for each share held on
all matters submitted to a vote of stockholders and do not have cumulative
voting rights. Accordingly, holders of a majority of the shares of Common
Stock entitled to vote in any election of directors may elect all of the
directors standing for election. Holders of Common Stock are entitled to
receive ratably such dividends, if any, as may be declared by the Board of
Directors out of funds legally available therefor and subject to any
preferential dividend rights of any then outstanding Preferred Stock. Upon the
liquidation, dissolution or winding up of the Company, the holders of Common
Stock are entitled to receive ratably the net assets of the Company available
after the payment of all debts and other liabilities and subject to any
liquidation preference of any then outstanding Preferred Stock. Holders of
Common Stock have no preemptive, subscription, redemption or conversion
rights. The outstanding shares of Common Stock are, and the shares offered by
the Company in this Offering will be, when issued and paid for, fully paid and
nonassessable.
   
  As of June 30, 1996, there were 6,373,023 shares of Common Stock outstanding
held by 84 stockholders (after giving effect to the conversion of all
outstanding shares of Preferred Stock into an aggregate of 5,366,869 shares of
Common Stock effective upon the closing of this Offering, but without giving
effect to Common Stock that may be issued after the closing of this Offering
to Bristol-Myers Squibb pursuant to certain antidilution rights of Bristol-
Myers Squibb).     
 
PREFERRED STOCK
 
  Upon the closing of this Offering, the Restated Certificate will have an
authorized class of undesignated preferred stock consisting of 5,000,000
shares, $0.001 par value per share. The Board of Directors will be authorized,
subject to any limitations prescribed by law, without further stockholder
approval, to issue from time to time shares of preferred stock in one or more
series. Each such series of preferred stock shall have such number of shares,
designations, preferences, voting powers, qualifications and special or
relative rights or privileges as shall be determined by the Board of
Directors, which may include, among others, dividend rights, voting rights,
redemption and sinking fund provisions, liquidation preferences, conversion
rights and preemptive rights.
 
  The rights of the holders of Common Stock will be subject to, and may be
adversely affected by, the rights of holders of any preferred stock that may
be issued in the future. Such rights may include voting and conversion rights
which could adversely affect the holders of Common Stock. Satisfaction of any
dividend preferences of outstanding preferred stock would reduce the amount of
funds available, if any, for the payment of dividends on Common Stock. See
"Dividend Policy." Holders of preferred stock would typically be entitled to
receive a preference payment in the event of a liquidation, dissolution or
winding up of the Company before any payment is made to the holders of Common
Stock. Additionally, the issuance of preferred stock could have the effect of
making it more difficult for a third party to acquire, or of discouraging a
third party from attempting to acquire, a majority of the outstanding voting
stock of the Company. The Company has no present plans to issue any shares of
preferred stock.
 
WARRANTS
 
  As of June 30, 1996, there were outstanding warrants exercisable for up to
86,619 shares of Common Stock (after giving effect to the conversion of all
outstanding warrants to purchase shares of the Company's
 
                                      57
<PAGE>
 
Preferred Stock into warrants for shares of Common Stock which will occur upon
the closing of this Offering). Such warrants have expiration dates ranging
from 2003 to 2006 and have a weighted average exercise price equal to $4.04
per share. The holders of the warrants are entitled to certain registration
rights in respect of the shares of Common Stock issuable upon exercise of
their respective warrants. See "Registration Rights."
 
REGISTRATION RIGHTS
 
  Certain persons and entities have rights with respect to the registration of
Common Stock under the Securities Act. Immediately after the closing of this
Offering, those rights will cover approximately 5,960,631 shares of Common
Stock (the "Registrable Shares"), which will include 86,619 shares of Common
Stock issuable upon exercise of warrants. In general, in the event that the
Company proposes to register any shares of Common Stock under the Securities
Act for its own account or the account of other stockholders at any time or
times, subject to certain exceptions, the Company must, upon the written
request of a holder of Registrable Shares, use its best efforts to cause to be
registered under the Securities Act all of the Registrable Shares requested to
be registered, provided, however, that the Company is not required to register
Registrable Securities in excess of the amount, if any, of Common Stock which
the principal underwriter of an underwritten offering shall agree to include
in such offering. The holders of 5,960,631 of the Registrable Shares will also
have the right to require the Company to prepare and file from time to time a
registration statement under the Securities Act with respect to their
Registrable Shares, provided that such holders may not exercise such right
more than once with respect to a registration statement on Form S-1 or more
than three times in any calendar year with respect to a registration statement
on Form S-3. Upon receipt of any such request from such holders, the Company
will be required to use its best efforts to effect such registration, subject
to certain conditions and limitations. If such holders are unable to include
in such registration statement on Form S-1 at least 90% of the Registrable
Shares that such holders have requested for inclusion, then such holders will
have the right to require that the Company prepare and file a second
registration statement on Form S-1 and the Company will be required to use its
best efforts to effect such registration, subject to certain conditions and
limitations.
 
 
DELAWARE LAW AND CERTAIN CHARTER AND BY-LAW PROVISIONS
 
  The Company is subject to the provisions of Section 203 of the DGCL. Subject
to certain exceptions, Section 203 prohibits a publicly held Delaware
corporation from engaging in a "business combination" with an "interested
stockholder" for a period of three years after the date of the transaction in
which the person became an interested stockholder, unless the interested
stockholder attained such status with the approval of the Board of Directors
or unless the business combination is approved in a prescribed manner. A
"business combination" includes certain mergers, asset sales and other
transactions resulting in a financial benefit to the interested stockholder.
Subject to certain exceptions, an "interested stockholder" is a person who,
together with his or her affiliates and associates, owns, or within three
years prior did own, 15% or more of the corporation's voting stock.
 
  The Restated Certificate of Incorporation and Amended and Restated By-Laws
(the "By-Laws") provide that, effective upon the consummation of this
Offering, any action required or permitted to be taken by the stockholders of
the Company may be taken only at duly called annual or special meetings of the
stockholders, and that special meetings may be called only by the Chairman of
the Board of Directors, the President or a majority of the Board of Directors
of the Company. These provisions could have the effect of delaying until the
next annual stockholders' meeting stockholder actions that are favored by the
holders of a majority of the outstanding voting securities of the Company,
including actions to remove directors. These provisions may also discourage
another person or entity from making a tender offer for the Company's Common
Stock, because such person or entity, even if it acquired all or a majority of
the outstanding voting securities of the Company, would be able to take action
as a stockholder (such as electing new directors or approving a merger) only
at a duly called stockholders meeting, and not by written consent.
 
 
                                      58
<PAGE>
 
          
  The Company's Restated Certificate of Incorporation and By-Laws provide
that, effective upon the consummation of this offering, for nominations for
the Board of Directors or for other business to be properly brought by a
stockholder before a meeting of stockholders, the stockholder must first have
given timely notice thereof in writing to the Secretary of the Company. To be
timely, a notice of nominations or other business to be brought before a
stockholders meeting must be delivered not less than 50 days prior to such
stockholders meeting, provided that in the event that less than 55 days'
notice or prior public disclosure of the date of the meeting is given or made
to stockholders, a notice of nominations or other business to be brought
before such stockholders meeting must be delivered within seven days following
the day on which such notice of the date of the stockholders meeting was given
or such public disclosure was made. The notice must contain, among other
things, certain information about the stockholder delivering the notice and,
as applicable, background information about each nominee or a description of
the proposed business to be brought before the meeting.     
 
  The DGCL provides generally that the affirmative vote of a majority of the
shares entitled to vote on any matter is required to amend a corporation's
certificate of incorporation or by-laws, unless the corporation's certificate
of incorporation or by-laws, as the case may be, requires a greater
percentage. The Company's Restated Certificate of Incorporation requires the
affirmative vote of the holders of at least 75% of the outstanding voting
stock of the Company to amend or repeal any of the foregoing provisions, or to
reduce the number of authorized shares of Common Stock and preferred stock. A
75% vote is also required to amend or repeal any of the foregoing By-Law
provisions. Such 75% stockholder vote would in either case be in addition to
any separate class vote that might in the future be required pursuant to the
terms of any preferred stock that might be outstanding at the time any such
amendments are submitted to stockholders. The By-Laws may also be amended or
repealed by a majority vote of the Board of Directors.
 
  The Company's Restated Certificate of Incorporation and By-Laws provide for
the division of the Board of Directors into three classes, as nearly equal in
size as possible, with staggered three-year terms. See "Management--Executive
Officers, Key Employees and Directors." Any director may be removed only for
cause and then only by the vote of a majority of the shares entitled to vote
for the election of directors.
 
  The Company's Restated Certificate of Incorporation empowers the Board of
Directors, when considering a tender offer or merger or acquisition proposal,
to take into account factors in addition to potential economic benefits to
stockholders. Such factors may include (i) comparison of the proposed
consideration to be received by stockholders in relation to the then current
market price of the Company's capital stock, the estimated current value of
the Company in a freely negotiated transaction and the estimated future value
of the Company as an independent entity, and (ii) the impact of such a
transaction on the employees, suppliers and customers of the Company and its
effect on the communities in which the Company operates.
 
  The foregoing provisions could have the effect of making it more difficult
for a third party to acquire, or of discouraging a third party from attempting
to acquire, control of the Company.
 
  The Company's Restated Certificate of Incorporation contains certain
provisions permitted under the DGCL relating to the liability of directors.
These provisions eliminate a director's personal liability for monetary
damages resulting from a breach of fiduciary duty, except in certain
circumstances involving certain wrongful acts, such as the breach of a
director's duty of loyalty or acts or omissions that involve intentional
misconduct or a knowing violation of law. These provisions do not limit or
eliminate the rights of the Company or any stockholder to seek non-monetary
relief, such as an injunction or rescission, in the event of a breach of a
director's fiduciary duty. There provisions will not alter a director's
liability under federal securities laws. The Company's Restated Certificate of
Incorporation and By-Laws also contain provisions indemnifying the directors
and officers of the Company to the fullest extent permitted by the DGCL. The
Company believes that these provisions will assist the Company in attracting
and retaining qualified individuals to serve as directors.
 
 
                                      59
<PAGE>
 
TRANSFER AGENT AND REGISTRAR
 
  The transfer agent and registrar for the Company's Common Stock is The First
National Bank of Boston.
 
                        SHARES ELIGIBLE FOR FUTURE SALE
   
  Upon completion of this Offering, the Company will have outstanding
8,373,023 shares of Common Stock. Of these shares, the 2,000,000 shares sold
in this Offering will be freely tradeable without restriction or further
registration under the Securities Act unless purchased by "affiliates" of the
Company as that term is defined in Rule 144 under the Securities Act. The
remaining 6,373,023 shares outstanding upon completion of this Offering will
be "restricted securities" as that term is defined under Rule 144 (the
"Restricted Shares"). Sales of Restricted Shares in the public market, or the
availability of such shares for sale, could adversely affect the market price
of the Common Stock. The executive officers, directors, employees and other
stockholders of the Company who beneficially own an aggregate of 6,373,023
shares of Common Stock outstanding prior to this Offering have agreed that
they will not, without the prior written consent of UBS Securities LLC, offer,
sell or otherwise dispose of any shares of Common Stock, options or warrants
to acquire shares of Common Stock or securities exchangeable for or
convertible into shares of Common Stock owned by them for a period of 180 days
after the effective date of this Offering (the "Lock-Up Period"). See
"Underwriting."     
   
  Upon expiration of the Lock-Up Period, approximately 177,139 Restricted
Shares held by non-affiliates will be eligible for sale in the public market
without restriction pursuant to Rule 144(k) and approximately 3,120,475
Restricted Shares held by affiliates and approximately 68,068 Restricted
Shares held by non-affiliates will be so eligible subject to compliance with
the volume limitations of Rule 144 described below. The remaining 2,547,809
Restricted Shares may be sold pursuant to Rule 144 only after they have been
fully paid for and held for at least two years from the later of the date of
issuance by the Company or acquisition from an affiliate (which dates do not
occur until after the expiration of the Lock-Up Period).     
   
  Beginning 90 days after the date of this Prospectus, certain shares issued
or issuable upon exercise of options granted by the Company prior to the date
of this Prospectus will also be eligible for sale in the public market
pursuant to Rule 701 under the Securities Act. In general, Rule 701 permits
resales of shares issued pursuant to certain compensatory benefit plans and
contracts commencing 90 days after the issuer becomes subject to the reporting
requirements of the Securities and Exchange Act of 1934, as amended, in
reliance upon Rule 144 but without compliance with certain restrictions,
including the holding period requirements, contained in Rule 144. If all the
requirements of Rule 701 are met, upon expiration of the Lock-Up Period an
aggregate of 459,482 shares of Common Stock currently outstanding, and an
aggregate of 520,660 shares of Common Stock issuable upon exercise of
currently outstanding options will be eligible for sale pursuant to such rule
commencing on the 181st day after this Prospectus.     
 
  In general, under Rule 144 as currently in effect, a person (or persons
whose shares are aggregated) who beneficially owned Restricted Shares for at
least two years, including persons who may be deemed "affiliates" of the
Company, would be entitled to sell within any three-month period a number of
shares that does not exceed the greater of one percent of the number of shares
of Common Stock then outstanding or the average weekly trading volume of the
Common Stock during the four calendar weeks preceding the filing of a Form 144
with respect to such sale. Sales under Rule 144 are also subject to certain
manner of sale provisions and notice requirements and to the availability of
current public information about the Company. In addition, a person who is not
deemed to have been an affiliate of the Company at any time during the 90 days
preceding the sale, and who has beneficially owned for at least three years
the shares proposed to be sold, would be entitled to sell such shares under
Rule 144(k) without regard to the requirements described above.
 
  The Securities and Exchange Commission has recently proposed reducing the
initial Rule 144 holding period to one year and the Rule 144(k) holding period
to two years. There can be no assurance as to when or whether such rule
changes will be enacted. If enacted, such modifications will have a material
effect on the times when shares of the Company's Common Stock become eligible
for resale.
 
                                      60
<PAGE>
 
  The Company is unable to estimate accurately the number of Restricted Shares
that will be sold under Rule 144 since this will depend in part on the market
price for the Common Stock, the personal circumstances of the sellers and
other factors.
 
  Rule 144A under the Securities Act would permit, subject to certain
conditions, the sale by the current holders of Restricted Shares of all or a
portion of their shares to certain "qualified institutional buyers," as
defined in Rule 144A.
 
  The Company intends to file a Form S-8 registration statement under the
Securities Act to register all shares of Common Stock issuable under the Plan.
That registration statement is expected to be filed within 180 days after the
date of this Prospectus and is expected to become effective immediately upon
filing. Shares covered by such registration statement will be eligible for
resale in the public market after the effective date of such registration
statements, subject to Rule 144 limitations applicable to affiliates and to
the Lockup Period, if applicable.
 
  In addition, upon completion of this Offering, the holders of 5,453,488
shares of Common Stock (including holders of warrants to purchase 86,619
shares of Common Stock) will be entitled to certain rights with respect to
registration of such shares under the Securities Act. Registration of such
shares under the Securities Act would result in such shares becoming freely
tradeable without restriction under the Securities Act (except for shares
purchased by affiliates of the Company) immediately upon the effectiveness of
such registration. See "Description of Capital Stock--Registration Rights."
 
                                      61
<PAGE>
 
                                 UNDERWRITING
 
  Subject to the terms and conditions of the Underwriting Agreement, the
underwriters named below (the "Underwriters"), for whom UBS Securities LLC,
Hambrecht & Quist LLC and Pacific Growth Equities, Inc. are acting as
representatives (the "Representatives"), have agreed to purchase from the
Company the following respective number of shares of Common Stock:
 
<TABLE>
<CAPTION>
                                                                       NUMBER OF
   UNDERWRITERS                                                         SHARES
   ------------                                                        ---------
   <S>                                                                 <C>
   UBS Securities LLC.................................................
   Hambrecht & Quist LLC..............................................
   Pacific Growth Equities, Inc.......................................
</TABLE>
 
<TABLE>     
   <S>                                                                 <C>
                                                                       ---------
       Total.......................................................... 2,000,000
                                                                       =========
</TABLE>    
 
  The Underwriting Agreement provides that the obligations of the Underwriters
are subject to certain conditions precedent, including the absence of any
material adverse change in the Company's business and the receipt of certain
certificates, opinions and letters from the Company and its counsel. The
nature of the Underwriters' obligation is such that they are committed to
purchase all shares of Common Stock offered hereby if any of such shares are
purchased. The Underwriting Agreement contains certain provisions whereby if
any Underwriter defaults in its obligation to purchase shares, and the
aggregate obligations of the Underwriters so defaulting do not exceed 10% of
the shares offered hereby, the remaining Underwriters, or some of them, must
assume such obligations.
 
  The Representatives have advised the Company that the Underwriters propose
to offer the shares of Common Stock directly to the public at the offering
price set forth on the cover of this Prospectus, and to certain dealers at
such price less a concession not in excess of $    per share. The Underwriters
may allow and such dealers may reallow a concession not in excess of $    per
share to certain other dealers. After the public offering of the shares of
Common Stock, the offering price and other selling terms may be changed by the
Underwriters.
   
  The Company has granted the Underwriters an option, exercisable no later
than 30 days after the date of this Prospectus, to purchase up to 300,000
additional shares of Common Stock to cover over-allotments, if any, at the
public offering price set forth on the cover page of this Prospectus, less the
underwriting discounts and commissions. To the extent that the Underwriters
exercise this option, each of the Underwriters will have a firm commitment to
purchase approximately the same percentage thereof which the number of shares
of Common Stock to be purchased by it shown in the above table bears to the
total number of shares of Common Stock offered hereby. The Company will be
obligated, pursuant to the option, to sell such shares to the Underwriters to
the extent the option is exercised.     
 
  The Company has agreed to indemnify the Underwriters against certain
liabilities, including liabilities under the Securities Act.
 
  The executive officers, directors, employees and other stockholders of the
Company who beneficially own an aggregate of 6,373,023 shares of Common Stock
outstanding prior to this Offering have agreed that they will not, without the
prior written consent of UBS Securities LLC, offer, sell or otherwise dispose
of any shares of Common Stock, options or warrants to acquire shares of Common
Stock or securities exchangeable for or convertible into shares of Common
Stock owned by them for a period of 180 days after the effective date of this
Offering. The Company has agreed that it will not, without the prior written
consent of UBS Securities LLC, offer, sell or otherwise dispose of any shares
of Common Stock, options or warrants to acquire
 
                                      62
<PAGE>
 
shares of Common Stock for a period of 180 days after the date of this
Prospectus, except that the Company may grant additional options under its
stock option plans, or issue shares upon the exercise of outstanding stock
options.
 
  The Representatives have advised the Company that the Underwriters do not
intend to confirm sales to any accounts over which they exercise discretionary
authority.
 
  Prior to this Offering, there has been no public market for the Common
Stock. The initial public offering price will be negotiated among the Company
and the Representatives. Among the factors to be considered in determining the
initial public offering price of the Common Stock, in addition to prevailing
market and economic conditions, are certain financial information of the
Company, the history of, and the prospects for, the Company and the industry
in which it competes, an assessment of the Company's management, its past and
present operations, the prospects for, and timing of, future revenues of the
Company, the present stage of the Company's development, and the above factors
in relation to market values and various valuation measures of other companies
engaged in activities similar to the Company. The initial public offering
price set forth on the cover page of this Prospectus should not, however, be
considered an indication of the actual value of the Common Stock. Such price
is subject to change as a result of market conditions and other factors. There
can be no assurance that an active trading market will develop for the Common
Stock or that the Common Stock will trade in the public market subsequent to
this Offering at or above the initial offering price.
 
  The Company has applied for listing of the Common Stock on the Nasdaq
National Market under the symbol "CBST."
 
                                 LEGAL MATTERS
 
  Bingham, Dana & Gould LLP, Boston, Massachusetts will pass on the validity
of the shares offered hereby for the Company. Justin P. Morreale, Esq., a
partner at Bingham, Dana & Gould LLP, is the Secretary of the Company and owns
42,857 shares of Common Stock. David L. Engel, Esq., a partner at Bingham,
Dana & Gould LLP, owns 5,952 shares of Common Stock. Certain legal matters
will be passed upon for the Underwriters by Hale and Dorr, Boston,
Massachusetts.
 
                                    EXPERTS
 
  The balance sheets of the Company as of December 31, 1994 and 1995 and the
related statements of operations, stockholders' equity and cash flows for each
of the three years in the period ended December 31, 1995 included in this
Prospectus and in the Registration Statement have been included herein in
reliance on the report of Coopers & Lybrand L.L.P., independent accountants,
given upon the authority of that firm as experts in accounting and auditing.
 
  The statement in this Prospectus under the captions "Risk Factors--
Uncertainty of Patents and Proprietary Rights" and "Business--Patents and
Proprietary Rights" have been reviewed and approved by Hamilton, Brook, Smith
& Reynolds, P.C. patent counsel to the Company, as experts on such matters,
and are included herein in reliance upon that review and approval. David E.
Brook, Esq., a shareholder at Hamilton, Brook, Smith & Reynolds, P.C. owns
14,285 shares of Common Stock. Dr. Helen Wendler, an attorney at Hamilton,
Brook, Smith & Reynolds, P.C., is the spouse of Dr. Philip Wendler. Dr. Philip
Wendler owns 10,285 shares of Common Stock and has stock options exercisable
for 26,142 shares of Common Stock.
 
                            ADDITIONAL INFORMATION
 
  The Company has filed with the Securities and Exchange Commission (the
"Commission"), a Registration Statement on Form S-1 under the Securities Act
of 1933, as amended (the "Securities Act") with respect to shares of Common
Stock offered hereby. This Prospectus does not contain all of the information
set forth in the Registration Statement and the exhibits and schedules
thereto. Statements contained in this Prospectus as to the contents of any
contract or other document filed as an exhibit to the Registration Statement
are qualified in all respects by such reference. For further information with
respect to the Company
 
                                      63
<PAGE>
 
and the Common Stock, reference is hereby made to the Registration Statement
and to the exhibits and schedules thereto, which may be inspected without
charge at the principal office of the Commission, 450 Fifth Street, N.W.,
Washington, D.C. 20549, and at the following regional offices of the
Commission: the New York Regional Office located at 7 World Trade Center,
Suite 1300, New York, New York 10048 and the Chicago Regional Office located
at the Northwest Atrium Center, 500 West Madison Street, Suite 1400, Chicago,
Illinois 60661. Copies of this material also may be obtained from the
Commission's Public Reference Section at 450 Fifth Street, N.W., Washington,
D.C. 20549, at prescribed rates. Such material may also be accessed
electronically by means of the Commission's home page on the Internet at
http://www.sec.gov.
 
  The Company intends to furnish its stockholders with annual reports
containing financial statements audited by its independent public accountants
and quarterly reports for the first three quarters of each fiscal year
containing unaudited consolidated financial information.
 
                                      64
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                         INDEX TO FINANCIAL STATEMENTS
 
<TABLE>   
<CAPTION>
                                                                            PAGE
                                                                            ----
<S>                                                                         <C>
Report of Independent Accountants.........................................  F-2
Balance Sheets as of December 31, 1994 and 1995 and June 30, 1996
 (unaudited) and June 30, 1996 Pro forma Stockholders' Equity
 (unaudited)..............................................................  F-3
Statements of Operations for the years ended December 31, 1993, 1994 and
 1995 and for the (unaudited) six month periods ended June 30, 1995 and
 1996.....................................................................  F-4
Statements of Cash Flows for the years ended December 31, 1993, 1994 and
 1995 and for the (unaudited) six month periods ended June 30, 1995 and
 1996.....................................................................  F-5
Statements of Changes in Stockholders' Equity for the years ended December
 31, 1993, 1994 and 1995 and for the (unaudited) six month period ended
 June 30, 1996............................................................  F-6
Notes to Financial Statements.............................................  F-8
</TABLE>    
 
                                      F-1
<PAGE>
 
This is the form of the opinion which will be issued upon effectiveness of the
stock split described in Note M to the financial statements.
 
                                          /s/ Coopers & Lybrand L.L.P.
                                          Coopers & Lybrand L.L.P.
 
Boston, Massachusetts
   
September 17, 1996     
 
                       REPORT OF INDEPENDENT ACCOUNTANTS
 
To the Board of Directors and Stockholders of Cubist Pharmaceuticals, Inc.:
 
  We have audited the accompanying balance sheets of Cubist Pharmaceuticals,
Inc. as of December 31, 1995 and 1994, and the related statements of
operations, stockholders' equity, and cash flows for each of the three years
in the period ended December 31, 1995. These financial statements are the
responsibility of the Company's management. Our responsibility is to express
an opinion on these financial statements based on our audits.
 
  We conducted our audits in accordance with generally accepted auditing
standards. Those standards require that we plan and perform the audit to
obtain reasonable assurance about whether the financial statements are free of
material misstatement. An audit includes examining, on a test basis, evidence
supporting the amounts and disclosures in the financial statements. An audit
also includes assessing the accounting principles used and significant
estimates made by management, as well as evaluating the overall financial
statement presentation. We believe that our audits provide a reasonable basis
for our opinion.
 
  In our opinion, the financial statements referred to above present fairly,
in all material respects, the financial position of Cubist Pharmaceuticals,
Inc. as of December 31, 1995 and 1994, and the results of its operations and
cash flows for each of the three years in the period ended December 31, 1995
in conformity with generally accepted accounting principles.
 
Boston, Massachusetts
January 12, 1996,
except as to the information
in Notes L and M, for which the
date is      , 1996
 
                                      F-2
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                                 BALANCE SHEETS
 
 
<TABLE>   
<CAPTION>
                                DECEMBER 31,
                          -------------------------
                                                                     PRO FORMA
                                                                   STOCKHOLDERS'
                                                       JUNE 30,       EQUITY
                             1994          1995          1996      JUNE 30, 1996
                          -----------  ------------  ------------  -------------
                                                            (unaudited)
<S>                       <C>          <C>           <C>           <C>
         ASSETS
Current Assets:
  Cash and cash
   equivalents..........  $ 1,220,983  $  2,049,555  $  4,732,273
  Short-term investments
   .....................          --      1,006,569           --
  Accounts receivable...          --        988,000     1,915,000
  Prepaid expenses and
   other current
   assets...............       82,709        66,996       734,086
                          -----------  ------------  ------------
  Total current assets..    1,303,692     4,111,120     7,381,359
Property and equipment..    3,282,436     3,834,953     4,171,086
  Less: Accumulated
   depreciation and
   amortization.........     (486,246)   (1,056,802)   (1,368,476)
                          -----------  ------------  ------------
  Property and
   equipment, net.......    2,796,190     2,778,151     2,802,610
Other assets............      150,181       158,571       171,260
                          -----------  ------------  ------------
    Total assets........  $ 4,250,063  $  7,047,842  $ 10,355,229
                          ===========  ============  ============
    LIABILITIES AND
  STOCKHOLDERS' EQUITY
Current Liabilities:
  Accounts payable......  $   375,270  $    124,856  $    413,266
  Accrued expenses......      647,353       189,663       768,614
  Deferred revenue......          --            --        550,000
  Current portion of
   long-term debt.......       96,997       168,565       177,164
  Current portion of
   capital lease
   obligations..........      276,062       413,223       449,646
                          -----------  ------------  ------------
    Total current
     liabilities........    1,395,682       896,307     2,358,690
Long-term debt, net of
 current portion........      346,943       479,745       389,378
Long-term capital lease
 obligation, net of
 current portion........      684,587       777,017       816,950
Venture capital bridge
 loan payable...........    1,000,000           --            --
                          -----------  ------------  ------------
    Total liabilities...    3,427,212     2,153,069     3,565,018
                          -----------  ------------  ------------
Commitments (Note I)
Stockholders' Equity:
Preferred Stock non-
 cumulative;
 convertible--$.001 par
 value; authorized
 43,000,000 shares;
 issued 1994 19,733,370
 shares; issued 1995
 34,751,183 shares;
 issued June 1996
 37,568,085 shares; and
 no shares issued pro
 forma..................       19,733        34,751        37,568  $        --
Common Stock--$.001 par
 value; authorized
 52,000,000 shares;
 issued 1994 910,027
 shares; issued 1995
 1,016,662 shares;
 issued June 30, 1996
 1,006,154 shares and
 6,373,023 shares pro
 forma..................          910         1,017         1,006         6,373
Additional paid-in
 capital................    7,338,075    16,790,878    20,756,723    20,788,924
Accumulated deficit.....   (6,535,867)  (11,931,873)  (14,005,086)  (14,005,086)
                          -----------  ------------  ------------  ------------
    Total stockholders'
     equity.............      822,851     4,894,773     6,790,211  $  6,790,211
                          -----------  ------------  ------------  ============
    Total liabilities
     and stockholders'
     equity.............  $ 4,250,063  $  7,047,842  $ 10,355,229
                          ===========  ============  ============
</TABLE>    
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-3
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                           STATEMENTS OF OPERATIONS
 
 
<TABLE>   
<CAPTION>
                                                                   SIX MONTHS ENDED
                          FOR THE YEARS ENDED DECEMBER 31,             JUNE 30,
                         -------------------------------------  ------------------------
                            1993         1994         1995         1995         1996
                         -----------  -----------  -----------  -----------  -----------
                                                                      (unaudited)
<S>                      <C>          <C>          <C>          <C>          <C>
Sponsored research
 revenues............... $       --   $       --   $ 1,271,333  $   100,000  $ 2,046,653
Operating expenses:
  Research and
   development..........   1,169,168    3,309,161    4,964,876    2,594,884    3,182,609
  General and
   administrative.......     546,843    1,448,928    1,708,513      818,977      873,586
                         -----------  -----------  -----------  -----------  -----------
    Total operating
     expenses...........   1,716,011    4,758,089    6,673,389    3,413,861    4,056,195
Interest income.........      45,028      113,338      239,030       90,312       43,232
Interest expense........     (16,911)    (168,284)    (232,980)    (100,806)    (106,903)
                         -----------  -----------  -----------  -----------  -----------
  Net loss.............. $(1,687,894) $(4,813,035) $(5,396,006) $(3,324,355) $(2,073,213)
                         ===========  ===========  ===========  ===========  ===========
Pro forma net loss per
 share (Note B).........                           $     (0.91)              $     (0.32)
                                                   ===========               ===========
Pro forma weighted
 average shares used in
 computing pro forma net
 loss per share (Note
 B).....................                             5,897,640                 6,449,282
                                                   ===========               ===========
</TABLE>    
 
 
   The accompanying notes are an integral part of the financial statements.
 
                                      F-4
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                            STATEMENTS OF CASH FLOWS
 
<TABLE>
<CAPTION>
                                                                    SIX MONTHS ENDED
                           FOR THE YEARS ENDED DECEMBER 31,             JUNE 30,
                          -------------------------------------  ------------------------
                             1993         1994         1995         1995         1996
                          -----------  -----------  -----------  -----------  -----------
                                                                       (UNAUDITED)
<S>                       <C>          <C>          <C>          <C>          <C>
Cash flows from
 operating activities:
 Net loss...............  $(1,687,894) $(4,813,035) $(5,396,006) $(3,324,355) $(2,073,213)
 Adjustments to
  reconcile net loss to
  net cash used in
  operating activities:
  Depreciation and
   amortization.........      130,269      355,977      570,556      265,914      311,674
  Changes in assets and
   liabilities:
   Accounts receivable..          --           --      (988,000)         --      (927,000)
   Prepaid expenses and
    other current
    assets..............      (69,669)     (12,688)      15,713      (32,279)    (667,090)
   Other assets.........      (58,112)         --        (8,390)         --           --
   Accounts payable and
    accrued expenses....      294,930      716,018     (708,104)    (655,757)     867,360
   Deferred revenue.....          --           --           --           --       550,000
                          -----------  -----------  -----------  -----------  -----------
    Total adjustments...      297,418    1,059,307   (1,118,225)    (422,122)     134,944
                          -----------  -----------  -----------  -----------  -----------
Net cash used in
 operating activities...   (1,390,476)  (3,753,728)  (6,514,231)  (3,746,477)  (1,938,269)
Cash flows from
 investing activities:
 Purchase of equipment..      (86,612)    (150,726)         --      (193,875)    (276,742)
 Leasehold
  improvements..........   (1,183,692)    (688,329)     (99,325)     (88,335)      (4,361)
 Purchase of short-term
  investments...........   (2,612,158)         --    (3,942,610)  (3,379,296)         --
 Redemption of short-
  term investments......          --     2,612,158    2,936,041      443,254    1,006,569
 Redemption of long-term
  investments...........     (511,934)     511,934          --           --           --
                          -----------  -----------  -----------  -----------  -----------
Net cash provided
 by/(used in) investing
 activities.............   (4,394,396)   2,285,037   (1,105,894)  (3,218,252)     725,466
Cash flows from
 financing activities:
 Issuance of stock......    6,709,690      148,314    8,467,928    8,008,850    3,968,651
 Proceeds from venture
  capital bridge loan...          --     1,000,000          --           --           --
 Proceeds from long-term
  debt..................      543,393          --       345,500      345,500          --
 Repayments of long-term
  debt..................      (13,373)     (86,080)    (141,130)     (64,229)     (81,767)
 Proceeds from capital
  lease financing.......          --           --        94,671      286,522      229,216
 Principal payments of
  capital lease
  obligations...........          --      (212,428)    (318,272)    (178,754)    (207,889)
 Deposits relating to
  capital lease
  obligations...........      (42,760)      (5,001)         --       (10,090)     (12,690)
                          -----------  -----------  -----------  -----------  -----------
Net cash provided by
 financing activities...    7,196,950      844,805    8,448,697    8,387,799    3,895,521
                          -----------  -----------  -----------  -----------  -----------
Net increase (decrease)
 in cash and cash
 equivalents............    1,412,078     (623,886)     828,572    1,423,070    2,682,718
Cash and cash
 equivalents at
 beginning of year......      432,791    1,844,869    1,220,983    1,220,983    2,049,555
                          -----------  -----------  -----------  -----------  -----------
Cash and cash
 equivalents at end of
 year...................  $ 1,844,869  $ 1,220,983  $ 2,049,555  $ 2,644,053  $ 4,732,273
                          ===========  ===========  ===========  ===========  ===========
Supplemental disclosures
 of cash flow
 information:
 Cash paid during the
  year for interest.....  $    16,911  $   168,284  $   232,980  $   100,806  $   106,903
 Capital lease
  obligations entered
  into..................  $   916,926  $   256,151  $   547,862  $   336,712  $   284,245
</TABLE>
 
Supplemental disclosure of non-cash transaction: Settlement of venture capital
bridge loan--Note G.
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-5
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                 STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY
 
  FOR THE YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995 AND FOR THE SIX MONTHS
                              ENDED JUNE 30, 1996
 
<TABLE>
<CAPTION>
                  # OF SHARES # OF SHARES # OF SHARES # OF SHARES # OF SHARES     $       $
                  PREFERRED A PREFERRED B PREFERRED C PREFERRED D   COMMON    PREFERRED COMMON
                  ----------- ----------- ----------- ----------- ----------- --------- ------
<S>               <C>         <C>         <C>         <C>         <C>         <C>       <C>
12/31/92
Balance.........   5,000,000          --          --        --      444,898    $ 5,000  $  445
                   ---------  ----------  ----------     -----      -------    -------  ------
Common Stock
Issued to
Consultants.....                                                     78,571                 79
Series B
Preferred Stock
par $.001 at
$.50 share......              14,270,000                                        14,270
Notes Receivable
Preferred
Stock...........
MIT Agreement
2% outstanding..                                                     23,170                 23
Exercise of
Common Stock
Options.........                                                        223
Net Loss........
                   ---------  ----------  ----------     -----      -------    -------  ------
12/31/93
Balance.........   5,000,000  14,270,000          --        --      546,862    $19,270  $  547
                   =========  ==========  ==========     =====      =======    =======  ======
Series B
Preferred Stock
par $.001 at
$.50 share......                 463,370                                           463
Common Stock par
$.007 at $.07
and $.35 share..                                                     60,714                 61
Exercise of
Common Stock
Options.........                                                    302,451                302
Notes Receivable
Preferred Series
B...............
Notes Receivable
Common Stock....
Issuance of
Stock Options...
Amortization of
Deferred
Compensation....
Net Loss........
                   ---------  ----------  ----------     -----      -------    -------  ------
12/31/94
Balance.........   5,000,000  14,733,370          --        --      910,027    $19,733  $  910
                   =========  ==========  ==========     =====      =======    =======  ======
<CAPTION>
                                   $
                      ADDITIONAL PAID-IN CAPITAL
                  ------------------------------------
                                                            $             $
                  ISSUANCE OF   NOTES       DEFERRED   ACCUMULATED  STOCKHOLDERS'
                    SHARES    RECEIVABLE  COMPENSATION   DEFICIT       EQUITY
                  ----------- ----------- ------------ ------------ -------------
<S>               <C>         <C>         <C>          <C>          <C>           <C>
12/31/92
Balance.........  $  495,269         --           --   $   (34,938)  $  465,776
                  ----------- ----------- ------------ ------------ -------------
Common Stock
Issued to
Consultants.....         471                                                550
Series B
Preferred Stock
par $.001 at
$.50 share......   7,120,730                                          7,135,000
Notes Receivable
Preferred
Stock...........              $(435,000)                               (435,000)
MIT Agreement
2% outstanding..       9,115                                              9,138
Exercise of
Common Stock
Options.........           2                                                  2
Net Loss........                                        (1,687,894)  (1,687,894)
                  ----------- ----------- ------------ ------------ -------------
12/31/93
Balance.........  $7,625,587  $(435,000)          --   ($1,722,832)  $5,487,572
                  =========== =========== ============ ============ =============
Series B
Preferred Stock
par $.001 at
$.50 share......     231,221                                            231,684
Common Stock par
$.007 at $.07
and $.35 share..      21,189                                             21,250
Exercise of
Common Stock
Options.........      86,485                                             86,787
Notes Receivable
Preferred Series
B...............               (131,685)                               (131,685)
Notes Receivable
Common Stock....                (65,842)                                (65,842)
Issuance of
Stock Options...      17,150                $(17,150)
Amortization of
Deferred
Compensation....                               6,120                      6,120
Net Loss........                                        (4,813,035)  (4,813,035)
                  ----------- ----------- ------------ ------------ ------------- ---
12/31/94
Balance.........  $7,981,632  $(632,527)    $(11,030)  $(6,535,867)  $  822,851
                  =========== =========== ============ ============ =============
</TABLE>
 
    The accompanying notes are an integral part of the financial statements.
 
                                      F-6
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
           STATEMENTS OF CHANGES IN STOCKHOLDERS' EQUITY (CONTINUED)
 
  FOR THE YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995 AND FOR THE SIX MONTHS
                              ENDED JUNE 30, 1996
<TABLE>   
<CAPTION>
                  # OF SHARES # OF SHARES # OF SHARES # OF SHARES # OF SHARES     $       $
                  PREFERRED A PREFERRED B PREFERRED C PREFERRED D   COMMON    PREFERRED COMMON
                  ----------- ----------- ----------- ----------- ----------- --------- ------
<S>               <C>         <C>         <C>         <C>         <C>         <C>       <C>
Series C
Preferred Stock
par $.001 at
$.60 share......                          15,017,813                           $15,018
Series C
Preferred Stock
Offering
Expenses........
Common Stock par
$.007 at $.35
and $.42 share..                                                     114,082               114
Exercise of
Common Stock
Options.........                                                         785                 1
Repurchase of
Common Stock....                                                      (8,232)               (8)
Repayment of
Notes Receivable
Preferred Series
B Notes
Receivable
Preferred Series
B...............
Notes Receivable
Common Stock....
Forgiveness of
Promissory
Notes...........
Issuance of
Stock Options...
Amortization of
Deferred
Compensation....
Net Loss
                   ---------  ----------  ----------   ---------   ---------   -------  ------
12/31/95
Balance.........   5,000,000  14,733,370  15,017,813          --   1,016,662   $34,751  $1,017
                   =========  ==========  ==========   =========   =========   =======  ======
Series D
Preferred Stock
par .001 at
$1.42 share.....                                       2,816,902               $ 2,817
Series D
Preferred Stock
Offering
Expenses........
Exercise of
Common Stock
Options.........                                                      19,042                19
Repurchase of
Common Stock....                                                     (29,550)              (30)
Amortization of
Deferred
Compensation....
Net Loss........
                   ---------  ----------  ----------   ---------   ---------   -------  ------
6/30/96 Balance
(unaudited).....   5,000,000  14,733,370  15,017,813   2,816,902   1,006,154   $37,568  $1,006
                   =========  ==========  ==========   =========   =========   =======  ======
<CAPTION>
                                   $
                      ADDITIONAL PAID-IN CAPITAL
                  -------------------------------------
                                                             $              $
                  ISSUANCE OF    NOTES       DEFERRED   ACCUMULATED   STOCKHOLDERS'
                    SHARES     RECEIVABLE  COMPENSATION   DEFICIT        EQUITY
                  ------------ ----------- ------------ ------------- ------------- ---
<S>               <C>          <C>         <C>          <C>           <C>           <C>
Series C
Preferred Stock
par $.001 at
$.60 share......    8,995,670                                           9,010,688
Series C
Preferred Stock
Offering
Expenses........      (45,787)                                            (45,787)
Common Stock par
$.007 at $.35
and $.42 share..       47,274                                              47,388
Exercise of
Common Stock
Options.........          274                                                 275
Repurchase of
Common Stock....       (2,873)                                             (2,881)
Repayment of
Notes Receivable
Preferred Series
B Notes
Receivable
Preferred Series
B...............                 435,000                                  435,000
Notes Receivable
Common Stock....                  (4,989)                                  (4,989)
Forgiveness of
Promissory
Notes...........                  23,615                                   23,615
Issuance of
Stock Options...       28,020                 (28,020)
Amortization of
Deferred
Compensation....                                4,619                       4,619
Net Loss                                                  (5,396,006)  (5,396,006)
                  ------------ ----------- ------------ ------------- ------------- ---
12/31/95
Balance.........  $17,004,210  $(178,901)    $(34,431)  $(11,931,873)  $4,894,773
                  ============ =========== ============ ============= ============= ===
Series D
Preferred Stock
par .001 at
$1.42 share.....    3,997,183                                           4,000,000
Series D
Preferred Stock
Offering
Expenses........     (38,410)                                            (38,410)
Exercise of
Common Stock
Options.........        7,580                                               7,599
Repurchase of
Common Stock....       (9,798)                                             (9,828)
Amortization of
Deferred
Compensation....                                9,290                       9,290
Net Loss........                                          (2,073,213)  (2,073,213)
                  ------------ ----------- ------------ ------------- ------------- ---
6/30/96 Balance
(unaudited).....  $20,960,765  $(178,901)    $(25,141)  $(14,005,086)  $6,790,211
                  ============ =========== ============ ============= ============= ===
</TABLE>    
    The accompanying notes are an integral part of the financial statements.
 
 
                                      F-7
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                         NOTES TO FINANCIAL STATEMENTS
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
 
A. NATURE OF BUSINESS
 
  Cubist Pharmaceuticals, Inc. ("Cubist" or the "Company") is a
biopharmaceutical company founded in May 1992 and is engaged in the research,
development and commercialization of novel classes of antiinfective drugs to
treat infectious diseases caused by bacteria and fungi, primarily those
resistant to existing antiinfective drugs. Cubist has established multiple
technology licenses and collaborations, has established a network of advisors
and collaborators and is located in Cambridge, Massachusetts. Prior to 1995,
the Company operated as a development stage enterprise, devoting substantially
all of its efforts to establishing the new business and carrying on research
and development activities.
 
B. ACCOUNTING POLICIES
 
 Basis of Presentation
 
  The accompanying financial statements are stated on an accrual basis.
 
 Use of Estimates
 
  The preparation of financial statements in conformity with generally
accepted accounting principles requires management to make certain estimates
and assumptions that affect the reported amounts of assets and liabilities, of
disclosure of contingent assets and liabilities at the date of the financial
statements, and of the reported amounts of revenues and expenses during the
reported period. Actual results could differ from those estimates.
 
 
 Cash Equivalents
 
  Cash equivalents consist of short-term interest-bearing instruments (U.S.
Government treasuries and money market accounts) with original maturities of
three months or less. These investments are carried at cost which approximates
market value.
 
 Short-term Investments
 
  Short-term investments, with an original maturity of more than three months
and less than one year when purchased, consisted entirely of U.S. Government
agency securities at December 31, 1995. Short-term investments, all of which
are held to maturity, are stated at amortized cost, which approximates market
value.
 
 Pro Forma Stockholders' Equity (Unaudited)
 
  Upon the closing of the Company's initial public offering, all of the
outstanding shares of Series A, B, C, and D Convertible preferred stock (the
"Preferred Stock") will automatically convert into 5,366,869 shares of common
stock. The unaudited pro forma presentation of stockholders' equity has been
prepared assuming the conversion of all the Preferred Stock into Common Stock
on June 30, 1996.
 
 Pro Forma Net Loss Per Common Share (Unaudited)
 
  The pro forma net loss per common share is computed based upon the weighted
average number of common shares and common equivalent shares (using the
treasury stock method) outstanding after certain adjustments described below.
Common equivalent shares are not included in the per share calculations where
the effect of their inclusion would be anti-dilutive, except that, in
accordance with Securities and Exchange Commission Staff Accounting Bulletin
No. 83, all common and common equivalent shares issued during the
 
                                      F-8
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                   NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                   UNAUDITED)
   
twelve-month period prior to the filing of the initial public offering, even
when anti-dilutive, have been included in the calculation as if they were
outstanding for all periods, using the treasury stock method and the expected
initial public offering price of $11.00 per share. The pro forma net loss per
common share gives effect to the mandatory conversion of all outstanding shares
of Preferred Stock into 5,366,869 shares of Common Stock upon the closing of
this offering.     
 
 Historical Net Loss Per Common Share
 
  Net loss per common share on a historical basis is computed in the same
manner as pro forma net loss per common share, except that Series A, B, C and D
Preferred Stock are not assumed to be converted. Net loss per common share on a
historical basis is as follows:
 
<TABLE>   
<CAPTION>
                                                                      SIX MONTHS
                               YEAR ENDED DECEMBER 31,              ENDED JUNE 30,
                         -------------------------------------  ------------------------
                            1993         1994         1995         1995         1996
                         -----------  -----------  -----------  -----------  -----------
<S>                      <C>          <C>          <C>          <C>          <C>
Net loss to common
 stockholders........... $(1,687,894) $(4,813,035) $(5,396,006) $(3,324,355) $(2,073,213)
Net loss per common
 share..................       (1.79)       (4.40)       (3.73)       (2.34)       (1.41)
Weighted average number
 of common and common
 equivalent shares
 outstanding............     942,306    1,093,181    1,446,914    1,420,923    1,471,562
</TABLE>    
 
  Fully diluted net loss per common share is the same as primary net loss per
common share.
 
 Property and Equipment
 
  Property and equipment are recorded at cost. Depreciation is provided using
the straight-line method over the estimated useful lives of the related assets,
generally three years for computer equipment and five years for laboratory
equipment, furniture and fixtures. Leasehold improvements are stated at cost
and are amortized over the lesser of the life of the lease or their estimated
useful lives. The leasehold improvements are also utilized as collateral up to
a value of $648,310, which relates to the balance of long-term debt.
Maintenance and repairs are charged to expense as incurred, while major
betterments are capitalized. When assets are retired or otherwise disposed of,
the assets and related allowances for depreciation and amortization are
eliminated from the accounts and any resulting gain or loss is reflected in
income.
 
 Research and Development
 
  All research and development costs are expensed as incurred.
 
 Income Taxes
 
  Research and experimentation and other tax credits, when utilized, will be
recorded using the flow-through method of accounting as a reduction of the
current provision for federal and state income taxes.
 
 Reclassification
 
  Certain amounts in the 1994 financial statements have been reclassified to
conform to the current year presentation.
 
 
                                      F-9
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                  NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
 Interim Financial Statements
 
  The balance sheet as of June 30, 1996, the statement of operations and cash
flows for the six months ended June 30, 1996 and 1995 and the statement of
changes in stockholder's equity for the six months ended June 30, 1996 are
unaudited, have been prepared on a basis substantially consistent with the
audited financial statements and, in the opinion of management, include all
adjustments (consisting of normal, recurring adjustments) necessary for a fair
presentation of results for these interim periods. The results for the six
months ended June 30, 1996 are not necessarily indicative of results to be
expected for the entire year, although the Company expects to incur a
significant loss for the year ending December 31, 1996.
 
 Recent Accounting Pronouncements
 
  In March 1995, the Financial Accounting Standards Board issued SFAS No. 121,
"Accounting for the Impairment of Long-Lived Assets and for Long-Lived Assets
to be Disposed Of." This standard is effective for financial statements for
fiscal years beginning after December 15, 1995. The Company's analysis of this
new standard indicates that it will not have a material effect on the
Company's financial position or results of operations.
 
  In October 1995, the Financial Accounting Standards Board issued SFAS No.
123, "Accounting for Stock-Based Compensation," which encourages companies to
recognize compensation expense in the statement of operations based on the
fair value of the underlying common stock at the date the awards are granted.
However, it will permit continued accounting under APB Opinion 25, "Accounting
for Stock Issued to Employees," accompanied by a disclosure of the pro forma
effects on net income/(loss) and earnings per share had the new accounting
rules been applied. The statement is effective for fiscal year 1996. The
Company has determined that it will elect the disclosure-only alternative
permitted under SFAS No. 123. The Company will be required to disclose pro
forma net income and pro forma earnings per share in the footnotes using the
fair value based method beginning in 1996 with comparable disclosures for
1995. The Company has not determined the impact of the pro forma adjustments
to its net income or earnings per share.
 
C. PROPERTY AND EQUIPMENT
 
  At December 31, property and equipment consisted of:
 
<TABLE>
<CAPTION>
                                                            1994        1995
                                                         ----------  ----------
   <S>                                                   <C>         <C>
   Leasehold improvements............................... $1,967,156  $2,066,480
   Laboratory equipment.................................    930,254   1,319,606
   Furniture and fixtures...............................    216,921     226,891
   Computer equipment...................................    168,105     221,976
                                                         ----------  ----------
                                                          3,282,436   3,834,953
   Less accumulated depreciation and amortization.......   (486,246) (1,056,802)
                                                         ----------  ----------
   Property and equipment, net.......................... $2,796,190  $2,778,151
                                                         ==========  ==========
</TABLE>
 
                                     F-10
<PAGE>
 
                          CUBIST PHARMACEUTICALS, INC.
 
                   NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
     
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                UNAUDITED)     
 
D. ACCRUED EXPENSES
 
  At December 31, accrued expenses consisted of:
 
<TABLE>
<CAPTION>
                                                                1994     1995
                                                              -------- --------
   <S>                                                        <C>      <C>
   Payroll and benefits...................................... $ 53,824 $ 57,723
   Vacation..................................................   41,863   40,255
   Construction..............................................  488,000      --
   Legal, audit and patent...................................   63,666   80,185
   Utilities.................................................      --    11,500
                                                              -------- --------
   Total accrued expenses.................................... $647,353 $189,663
                                                              ======== ========
</TABLE>
 
E. LICENSE AGREEMENT
 
  The Company has entered into two agreements with the Massachusetts Institute
of Technology ("MIT"), pursuant to which MIT has granted the Company exclusive
worldwide licenses to certain patent rights owned by MIT. The Company has the
right to sell or license worldwide any product or process derived from these
patent rights. In return for these licenses, the Company has paid to MIT
license issue fees of $50,000 and $75,000, respectively. The Company also has
paid license maintenance fees of $25,000 in total each year commencing January
1, 1994. In addition, the Company issued shares of common stock equal to 2% of
the outstanding common and preferred shares at the completion of the Series B
round of financing and will pay royalties from future sales. License fees are
expensed as incurred.
 
F. COLLABORATIVE RESEARCH AGREEMENT
   
  On December 15, 1995, the Company entered into a collaborative research
agreement with Pfizer. Under the terms of the agreement, Pfizer is required to
pay the Company a technology licensing fee upon execution and research support
payments. These payments are recognized as income earned under the terms of the
agreement. In addition, Pfizer will reimburse the Company for expenses related
to the screening of Pfizer compounds against the Company's targets and certain
milestone payments. These payments are recognized as revenue when the related
expenses are incurred. During 1995, the Company included in sponsored research
revenues $500,000 for the technology licensing fee and $488,000 for certain
research and development revenues in accordance with the agreement. Pfizer also
has an option to initiate a drug discovery program using compounds from the
drug screening program. Upon initiation of a drug discovery program, Pfizer is
obligated to purchase $5,000,000 of the Company's Preferred Stock.     
 
G. STOCKHOLDERS' EQUITY
 
 Preferred Stock
   
  In February 1995, the Company sold an aggregate of 9,428,644 shares of its
Series C Convertible Preferred Stock at a purchase price of $0.60 per share to
a group of existing investors. The purchase price of the Series C Convertible
Preferred Stock was paid in part by the conversion and cancellation of
$1,000,000 of Convertible Demand Promissory Notes which had been issued in
December 1994 to certain existing investors.     
   
  Upon consummation of the reverse stock split of Common Stock described in
footnote M, the Company's Convertible Preferred Stock will be convertible to
Common Stock at a rate of 1 common share to 7 preferred shares (refer to
footnote M) at the option of the shareholder. The Company's Preferred Stock
will automatically convert into Common Stock at a rate of 1 common share to 7
preferred shares upon the     
 
                                      F-11
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                  NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
   
first public offering where proceeds exceed $15,000,000 and the per share
price exceeds $10.92. The Company has also granted warrants to purchase
240,500 shares of Series B Convertible Preferred Stock at a purchase price of
$0.50, 92,500 shares of Series C Convertible Preferred Stock at a purchase
price of $0.60 and 33,333 shares of Series C Convertible Preferred Stock at a
purchase price of $0.90 per share. These warrants expire on either the fifth
anniversary of the closing of an initial public offering of the Company's
Common Stock or on August 30, 2003, February 28, 2005 and February 26, 2006,
respectively, whichever is earlier.     
 
 Common Stock
 
  As of December 31, 1995, 1,016,662 shares of Common Stock were issued to
employees, scientific founders and consultants of the Company. Certain of
these shares issued are subject to repurchase, at the Company's option, at the
original issuance price in accordance with vesting provisions upon termination
of the relationship. At December 31, 1995, 306,350 shares remain subject to
repurchase.
 
 Notes Receivable from Related Parties
 
  The Company has accepted promissory notes from the Chief Executive Officer
in consideration for the Preferred Stock and Common Stock options issued to
him. The aggregate principal amount of these notes at December 31, 1995 is
$178,901 and is reflected in stockholders' equity as a reduction to paid-in
capital. These notes have an annual interest rate of 4% and fall due between
July 21, 1996 and November 28, 1997. During 1995, $23,615 of principal and
accrued interest under the promissory notes was forgiven and it its expected
that additional amounts will be forgiven in 1996 and 1997.
 
H. STOCK OPTIONS
 
  The Company has a stock option plan under which options to purchase 571,428
shares of its Common Stock may be granted to employees, directors, officers or
consultants. The options are granted at fair market value on the date of the
grant as determined by the Board of Directors, vest ratably over a four-year
period and expire ten years from the date of grant. In addition, the Company
has issued to certain consultants and directors nonqualified stock options to
purchase 73,428 shares of its Common Stock. During 1995 and 1994, the Company
has allowed employees and consultants to exercise their full grants to take
advantage of certain favorable tax benefits. The Company has reserved the
right to repurchase any unearned shares at the original purchase price if the
employee or consultant does not fulfill their vesting requirement.
 
                                     F-12
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                  NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
 
  From inception to December 31, 1995, the Company granted options for 380,857
shares (net of cancellations and repurchased shares) under its stock option
plan at prices ranging from $0.07 to $0.42 per share, of which options for
255,371 shares were exercised at prices ranging from $0.07 to $0.42. There
were 25,617 employee shares exercisable at year-end (32,303 shares at December
31, 1994). The Company has granted options for 73,428 shares to consultants
and directors under its stock option plan, of which 39,857 options were
exercised since inception. Stock option activity is summarized as follows:
 
<TABLE>
<CAPTION>
                                                            SHARES  OPTION PRICE
                                                            ------- ------------
   <S>                                                      <C>     <C>
   Outstanding at December 31, 1993........................ 124,571  $ .07-$.35
     Granted............................................... 227,335  $ .07-$.35
     Exercised............................................. 302,451  $ .07-$.35
     Cancelled.............................................   7,241  $ .07-$.35
                                                            -------  ----------
   Outstanding at December 31, 1994........................  42,214  $ .07-$.35
     Granted............................................... 121,442  $ .07-$.42
     Exercised.............................................     785  $ .07-$.35
     Cancelled.............................................   3,814  $ .07-$.35
                                                            -------  ----------
   Outstanding at December 31, 1995........................ 159,057  $ .07-$.42
     Granted............................................... 384,715  $.42-$5.95
     Exercised.............................................  15,627  $ .35-$.42
     Cancelled.............................................   7,485  $ .35-$.42
                                                            -------  ----------
   Outstanding at June 30, 1996 (unaudited)................ 520,660  $.07-$5.95
                                                            =======  ==========
</TABLE>
 
  During 1995, 8,232 shares of previously exercised options were repurchased
because vesting schedules were not fulfilled. These options were originally
exercised during 1994.
 
I. LEASE COMMITMENTS
 
  The Company leases its facilities under an operating lease agreement which
expires on September 15, 2003 and is renewable at the Company's option for one
additional five-year period. Under the terms of the lease, the Company is
obligated to pay its prorated share of common operating expenses and real
estate taxes as well as base rents. In addition, the Company entered into an
amendment to the agreement with the landlord under which the landlord provided
financing to the Company for a portion of the buildout cost ($543,393) at an
interest rate of 12% per year payable in equal monthly installments of $19,773
over five years through October 1998, and $7,685 thereafter through February
2000. At December 31, 1995, the outstanding principal balance was $347,070.
The Company also provided a security deposit of $100,000 upon execution of the
lease. The security deposit bears interest in a segregated account, and is
partially refundable ($79,000 plus interest) upon the fifth anniversary, and
fully refundable plus interest within thirty days after the expiration of the
lease, provided no event of default has occurred. The Company has also
financed an additional $345,500 during the first quarter of 1995 relating to a
6,510 square foot facility expansion completed during the first week of
January 1995. This additional debt is payable over five years with an annual
interest rate of 12%. No additional security deposit was required. At December
31, 1995, the outstanding principal balance was $301,240.
 
                                     F-13
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                  NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
 
  The Company leases certain laboratory equipment under long-term capital
leases. The cost of this equipment included in fixed assets was $1,720,940 at
the end of 1995 and $1,173,078 at the end of 1994, with associated accumulated
depreciation of $627,366 at December 31, 1995 and $302,621 at December 31,
1994. The Company has an option to purchase all of the leased equipment at a
price to be negotiated at lease end. Future lease payments for non-cancelable
leases for the respective years ended December 31 are as follows:
 
<TABLE>
<CAPTION>
                                      OPERATING LEASES                 CAPITAL LEASES
                                      ----------------                 --------------
<S>                                   <C>                              <C>
    1996                                 $  148,615                      $  520,060
    1997                                    148,615                         520,060
    1998                                    157,676                         220,969
    1999                                    179,680                         105,568
    2000                                    179,680                             --
    2001 and thereafter                     486,444                             --
                                         ----------                      ----------
Total minimum lease payments             $1,300,710                       1,366,657
                                         ----------                      ----------
Less amount representing interest payments                                  176,417
                                                                         ----------
Present value of minimum lease payments                                   1,190,240
Less current portion                                                        413,223
                                                                         ----------
Long-term obligation                                                     $  777,017
                                                                         ==========
</TABLE>
 
  Lease payments under operating leases were $207,898 in fiscal year 1995 and
$269,991 in fiscal year 1994.
 
J. EMPLOYEE BENEFITS
 
  The Company instituted a 401(k) savings plan in 1993, in which substantially
all of its permanent employees are eligible to participate. Participants may
contribute up to 15% of their annual compensation to the plan, subject to
certain limitations. The Company contributes a matching amount of up to 1.5%
of a participant's total compensation or $500 annually, whichever is less. The
Company contributed $14,072 during 1995 and $9,524 during 1994.
 
K. INCOME TAXES
 
  The Company follows the liability method of accounting for income taxes in
accordance with the provisions of Statement of Financial Accounting Standards
(SFAS) No. 109, "Accounting for Income Taxes," whereby a deferred tax
liability is measured by the enacted tax rates which will be in effect when
any differences between the financial statements and tax basis of assets
reverse. The deferred tax liability can be reduced by net operating losses
being carried forward for tax purposes.
 
  At December 31, 1995, the Company had available federal and state net
operating loss carryforwards of approximately $11,678,000. The federal and
state net operating loss and tax credit carryforwards begin to expire in the
years 2007 and 1997, respectively. Research and experimentation tax credits of
approximately $325,000 begin to expire in 2008. The net operating loss
carryforwards may be subject to an annual limitation in any given year in the
event of certain occurrences, including significant changes in ownership. The
Company has established a valuation reserve against the deferred tax benefit
arising from these carryforwards due to the uncertainty of earning sufficient
taxable income to receive the benefit and accordingly has not given
recognition to these tax benefits in these financial statements. These
carryforwards are also subject to review by the Internal Revenue Service.
 
                                     F-14
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.
 
                  NOTES TO FINANCIAL STATEMENTS--(CONTINUED)
 
  (INFORMATION WITH RESPECT TO THE SIX MONTHS ENDED JUNE 30, 1995 AND 1996 IS
                                  UNAUDITED)
 
L. SUBSEQUENT EVENTS
 
 Collaborative Agreements
 
  In June 1996, the Company entered into a collaborative research agreement
with Bristol-Myers Squibb. Under the terms of the agreement, Bristol-Myers
Squibb purchased from the Company $4,000,000 of the Company's Preferred Stock
upon execution of the agreement, and has agreed to make payments to the
Company upon the achievement of certain milestones. These milestone payments
are recognized as income as earned under the terms of the agreement. In
addition, Bristol-Myers Squibb will reimburse the Company for research and
development expenses relating to the production of certain targets and also
for expenses relating to the screening of Bristol-Myers Squibb compounds
against the Company's targets over three years, with an option to fund a
fourth year. These payments are recognized as revenue when the related
expenses are incurred.
 
  In June 1996, the Company entered into a collaborative research agreement
with Merck & Co., Inc. ("Merck"). Under the terms of the agreement, Merck will
pay the Company a technology licensing fee upon execution and certain
milestone payments. These payments are recognized as income as earned under
the terms of the agreement. In addition, Merck will reimburse the Company for
research and development expenses relating to the production of certain
targets; for expenses relating to the screening of Merck compounds against the
Company's targets; and for expenses relating to compound optimization. These
payments are recognized as revenue when the related expenses are incurred.
 
 Common Stock Option Grants
 
  On May 28, 1996, the Company granted 214,285 incentive stock options to
certain employees of the Company at a purchase price of $1.96 per share. In
addition, the Company issued 42,857 shares of non-qualified options at an
exercise price of $1.96 per share to directors of the Company. On June 11,
1996, the Company granted 4,285 incentive stock options to certain employees
of the Company at a purchase price of $5.95 per share, and the Company granted
10,714 nonstatutory stock options to a director and a consultant of the
Company at a purchase price of $5.95 per share. In addition, in June 1996, the
Company increased the options available for grant under the Amended and
Restated 1993 Stock Option Plan to 1,500,000 shares.
 
 Warrants
 
  During February 1996, the Company issued a warrant exercisable for 33,333
shares of Series C Convertible Preferred Stock (convertible to Common Stock
upon the closing of the Company's initial public offering) to Comdisco, Inc.
in conjunction with a $500,000 increase of the Company's equipment lease line
over 1996.
 
M. REVERSE STOCK SPLIT
 
  The Company anticipates that in September 1996 it will effect a 1-for-7
reverse stock split of the Common Stock. Accordingly, all share and per share
amounts have been adjusted to reflect the stock split as though it had
occurred at the beginning of the initial period presented.
 
                                     F-15
<PAGE>
 
                   INHIBITION OF AMINOACYL - TRNA SYNTHETASE
 
 
       Amino Acid                                     Inhibitor
 
 
                      Aminoacyl - tRNA Synthetase
 
                                         tRNA
                          Charged tRNA                                Inhibited
                                                                      Synthetase
 
    Protein Synthesis                            Inhibition of Protein
                                                       Synthesis
 
 
Binding of an amino acid
to the aminoacyl -tRNA                        Binding of an inhibitor to
synthetase leads to the                       the aminoacyl - tRNA
formation of charged                          synthetase alters the
tRNA and protein                              synthetase structure,
synthesis.                                    blocks amino acid binding
                                              and prevents the formation
                                              of charged tRNA, thereby
                                              inhibiting protein
                                              synthesis.
 
- --------------------------------------------------------------------------------
 
             AMINOACYL - TRNA SYNTHETASE TARGETS FOR DRUG DISCOVERY
 
 
 
                                                                         S.
                                                                         aureus
                                                                        E.
                                                                        faecalis
                                                                       C.
                                                                       albicans
                                                                      H.
                                                                      influenzae
                                                                     S.
                                                                     pneumoniae
                                                                    E. coli
     1  2  3  4  5  6  7  8  9  10  11  12  13  14  15  16  17 18 19 20
                          Aminoacyl - tRNA Synthetases
 
Elevated cubes represent certain screening leads that exhibit significant
inhibitory activity against specific aminoacyl - tRNA synthetase targets.
Glutamine - tRNA synthetase, shown in black, is not present in certain
pathogens.

<PAGE>
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
 
 No dealer, salesperson, or any other person has been authorized to give any
information or to make any representations not contained in this Prospectus in
connection with the offer made by this Prospectus and, if given or made, such
information or representations must not be relied upon as having been
authorized by the Company or the Underwriter. This Prospectus does not
constitute an offer to sell or a solicitation of an offer to buy any of the
securities offered hereby by anyone in any jurisdiction in which such offer or
solicitation is not authorized or in which the person making such offer or
solicitation is not qualified to do so or to anyone to whom it is unlawful to
make such offer or solicitation. Neither the delivery of this Prospectus nor
any sale made hereunder shall, under any circumstances, create any implication
that the information herein is correct as of any time subsequent to the date
of this Prospectus.
 
                                --------------
 
                               Table of Contents
 
 
<TABLE>   
<CAPTION>
                                                                          Page
                                                                          ----
<S>                                                                       <C>
Prospectus Summary.......................................................   3
Risk Factors.............................................................   6
Use of Proceeds..........................................................  14
Dividend Policy..........................................................  14
Capitalization...........................................................  15
Dilution.................................................................  16
Selected Financial Data..................................................  17
Management's Discussion and Analysis of Financial Condition and Results
 of Operations...........................................................  18
Business.................................................................  22
Management...............................................................  46
Certain Transactions.....................................................  52
Principal Stockholders...................................................  54
Description of Capital Stock.............................................  57
Shares Eligible for Future Sale..........................................  60
Underwriting.............................................................  62
Legal Matters............................................................  63
Experts..................................................................  63
Additional Information...................................................  63
Index to Financial Statements............................................ F-1
</TABLE>    
 
 Until       , 1996 (25 days after the date of the Prospectus), all dealers
effecting transactions in the registered securities, whether or not
participating in this distribution, may be required to deliver a Prospectus.
This is in addition to the obligation of dealers to deliver a Prospectus when
acting as underwriters and with respect to their unsold allotments or
subscriptions.
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
                                
                             2,000,000 SHARES     
                                      
                                   LOGO     
 
                         CUBIST PHARMACEUTICALS, INC.
 
                                 COMMON STOCK
 
                             --------------------
 
                                  PROSPECTUS
                                       , 1996
 
                             --------------------
 
                                UBS SECURITIES
 
                               HAMBRECHT & QUIST
 
                         PACIFIC GROWTH EQUITIES, INC.
 
- -------------------------------------------------------------------------------
- -------------------------------------------------------------------------------
<PAGE>
 
                                    PART II
 
                    INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
  Expenses of the Registrant in connection with the issuance and distribution
of the securities being registered, other than the underwriting discount, are
estimated as follows:
 
<TABLE>
<CAPTION>
  <S>                                                                 <C>
  SEC Registration Fee............................................... $ 12,888
  NASD Fees..........................................................    4,238
  Nasdaq National Market Listing Fees................................   39,696
  Printing and Engraving Expenses....................................  100,000
  Legal Fees and Expenses............................................  225,000
  Accountants' Fees and Expenses.....................................  125,000
  Expenses of Qualification Under State Securities Laws, Including
   Attorneys' Fees...................................................   20,000
  Transfer Agent and Registrar's Fees................................   10,000
  Miscellaneous Costs................................................   63,178
                                                                      --------
      Total.......................................................... $600,000
                                                                      ========
</TABLE>
 
- --------
ITEM 14.  INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
  Section 145 of the Delaware General Corporation Law empowers a Delaware
corporation to indemnify its officers and directors and certain other persons
to the extent and under the circumstances set forth therein.
 
  The Restated Certificate of Incorporation and the Amended and Restated By-
Laws of the Company, copies of which are filed herein as Exhibit 3.3 and 3.4,
provide for advancement of expenses and indemnification of officers and
directors of the Registrant and certain other persons against liabilities and
expenses incurred by any of them in certain stated proceedings and under
certain stated conditions to the fullest extent permissible under Delaware
law.
 
  Section 9 of the Underwriting Agreement between the Registrant and the
Underwriters, a copy of which is filed herein as Exhibit 1.1, will provide for
indemnification by the Registrant of the Underwriters and each person, if any,
who controls any Underwriter, against certain liabilities and expenses, as
stated therein, which may include liabilities under the Securities Act of
1933. The Underwriting Agreement also provides that the Underwriters shall
similarly indemnify the Registrant, its directors, officers and controlling
persons, as set forth therein.
 
ITEM 15. RECENT SALES OF UNREGISTERED SECURITIES
 
  Described below is information regarding all unregistered securities of the
Company sold by the Company within the past three years. The share and per
share amounts set forth below have been adjusted to reflect the Company's one
for seven reverse stock split to occur prior to the consummation of this
Offering.
 
  Between incorporation (May 1992) and June 1996, the Company has issued and
sold an aggregate of approximately 459,513 shares of its Common Stock, at
prices ranging from $0.007 to $0.42 per share, with an aggregate offering
price of approximately $150,601 to certain of its officers, employees and
consultants. The offers and sales of these shares were made in reliance upon
Rule 701 promulgated under the Securities Act and are deemed to be exempt
transactions as sales of an issuer's securities pursuant to a written plan or
contract relating to the compensation of such individuals and upon Section
4(2) of the Securities Act as transactions not involving any public offering.
 
                                     II-1
<PAGE>
 
  From its incorporation (May 1992) to June 1996, the Registrant has entered
into stock option agreements with certain employees, officers, directors and
consultants to the Company covering approximately 827,337 shares of its Common
Stock pursuant to the Registrant's Amended and Restated 1993 Stock Option
Plan. The purchase price under the options is $0.007 to $5.95 per share based
on the fair market value of the Common Stock on the date of grant. These
grants and sales were made in reliance upon Rule 701 under the Securities Act
and are deemed to be exempt transactions as sales of an issuer's securities
pursuant to a written contract relating to the compensation of such
individuals.
 
  In August 1993, the Registrant issued and sold an aggregate of 14,270,000
shares of Series B Convertible Preferred Stock (convertible into 2,038,571
shares of Common Stock) at a purchase price of $0.50 per share ($3.50 per
share on an as-converted basis), to a group of investors. The issuance and
sales of such shares of Series B Convertible Preferred Stock were made in
reliance upon Rule 506 of Regulation D promulgated under the Securities Act
and Section 4(2) of the Securities Act.
 
  In August 1993, the Registrant issued a warrant for the purchase of 240,500
shares of Series B Convertible Preferred Stock (convertible into 34,357 shares
of Common Stock) at an exercise price of $0.50 per share to Comdisco ($3.50
per share on an as-converted basis). In January 1994, the Company issued and
sold an aggregate of 200,000 shares of Series B Convertible Preferred Stock
(convertible into 28,571 shares of Common Stock) at a purchase price of $0.50
per share ($3.50 per share on an as-converted basis) to Comdisco, Inc. The
issuance and sale of such warrant and shares for the purchase of Series B
Convertible Preferred Stock were made in reliance upon Section 4(2) of the
Securities Act.
 
  In January 1994, the Registrant issued and sold 39,496 shares of Common
Stock to the Massachusetts Institute of Technology ("MIT") pursuant to a
License Agreement between MIT and the Company. The issuance and sale of such
shares of Common Stock were made in reliance upon Section 4(2) of the
Securities Act.
 
  In July 1994, the Registrant issued and sold 263,370 shares of Series B
Preferred Stock (convertible into 37,624 shares of Common Stock) at a purchase
price of $0.50 per share ($3.50 per share on an as-converted basis) to Dr.
Scott M. Rocklage, President, Chief Executive Officer and a director of the
Company. The issuance and sale of such shares of Series B Preferred Stock were
made in reliance upon Section 4(2) of the Securities Act.
 
  In December 1994, the Registrant issued $1,000,000 of Convertible Demand
Promissory Notes (the "Notes") to a group of investors. The Notes were issued
in reliance upon Section 4(2) of the Securities Act. The entire amount of
indebtedness was converted to 1,684,644 shares of Series C Convertible
Preferred Stock (convertible into approximately 240,663 shares of Common
Stock) in connection with an offering of Series C Convertible Preferred Stock
in February 1995.
 
  In February 1995, the Registrant issued and sold an aggregate of 7,744,000
shares of Series C Convertible Preferred Stock (convertible into approximately
1,106,285 shares of Common Stock) to a group of investors, at a purchase price
of $0.60 per share ($4.20 per share on an as-converted basis). In addition,
the Registrant issued a warrant to Comdisco, Inc. to purchase 92,500 shares
(convertible into 13,214 shares of Common Stock) at an exercise price of $0.60
per share ($4.20 per share on an as-converted basis). The issuance and sales
of such shares of Series C Convertible Preferred Stock were made in reliance
upon Rule 506 of Regulation D promulgated under the Securities Act and Section
4(2) of the Securities Act.
 
  In May 1995, the Registrant issued and sold an aggregate of 5,589,169 shares
of Series C Convertible Preferred Stock (convertible into approximately
798,452 shares of Common Stock) at a purchase price of $0.60 per share ($4.20
per share on an as-converted basis) to a group of investors. In addition, the
Registrant issued options to each of Dr. Schimmel and Dr. Rebek, to purchase
120,000 shares of Series C Convertible Preferred Stock (convertible into
17,142 shares of Common Stock) at an exercise price of $0.60 per share ($4.20
per share on an as-converted basis). The issuance and sales of such shares of
and options for Series C Convertible Preferred Stock were made in reliance
upon Rule 506 of Regulation D promulgated under the Securities Act and Section
4(2) of the Securities Act.
 
                                     II-2
<PAGE>
 
  In February 1996, the Registrant issued a warrant to Comdisco, Inc. for up
to 33,333 shares of Series C Convertible Preferred Stock (convertible into
4,761 shares of Common Stock) at an exercise price of $0.90 per share ($6.30
per share on an as-converted basis). The issuance and sale of such shares of
Series C Convertible Preferred Stock were made in reliance upon Section 4(2)
of the Securities Act.
   
  In June 1996, the Registrant issued 2,816,902 shares of Series D Convertible
Preferred Stock (convertible into 402,414 shares of Common Stock) to Bristol-
Myers Squibb Company at a purchase price of $1.42 per share ($9.94 per share
on an as-converted basis). The issuance and sale of such shares of Series D
Convertible Preferred Stock were made in reliance upon Section 4(2) of the
Securities Act. In addition, the Company may issue Common Stock after the
closing of this Offering to Bristol-Myers Squibb pursuant to certain
antidilution rights of Bristol-Myers Squibb.     
 
ITEM 16. EXHIBITS AND FINANCIAL STATEMENT SCHEDULES
 
  (a) Exhibits:
 
<TABLE>   
<CAPTION>
 EXHIBITS
 --------
 <C>      <S>
 *1.1     Proposed Form of Underwriting Agreement.
  3.1     Restated Certificate of Incorporation of the Registrant.
  3.2     Form of Certificate of Amendment to the Restated Certificate of
          Incorporation of the Registrant (to be filed with the Secretary of
          State of the State of Delaware prior to the effectiveness of the
          Registration Statement).
  3.3     Form of Restated Certificate of Incorporation of the Registrant (to
          be filed with the Secretary of State of the State of Delaware upon
          the closing of the Offering).
  3.4     Amended and Restated By-Laws of the Registrant, as amended to date.
  4.1     Specimen certificate for shares of Common Stock.
 *4.2     Description of Capital Stock (contained in the Restated Certificate
          of Incorporation of the Corporation of the Registrant, filed as
          Exhibit 3.3).
  5.1     Opinion of Bingham, Dana & Gould LLP, with respect to the legality of
          the shares being registered.
+10.1     (a) License Agreement between the Registrant and the Massachusetts
          Institute of Technology, dated November 4, 1992, as amended by the
          First Amendment, dated January 20, 1995, and the Second Amendment,
          dated May 17, 1995.
          (b) Patent License Agreement between the Registrant and the
          Massachusetts Institute of Technology, dated July 21, 1994.
+10.2     License Agreement between the Registrant and the Board of Trustees of
          the Leland Stanford Junior University, dated April 1, 1994.
*10.3     Employment Agreement between the Registrant and Scott M. Rocklage,
          dated June 20, 1994.
*10.4     Consulting Agreement between the Registrant and Paul R. Schimmel,
          dated May 1, 1992.
*10.5     Consulting Agreement between the Registrant and Julius Rebek, Jr.,
          dated May 1, 1992.
 10.6     Amended and Restated 1993 Stock Option Plan.
+10.7     Collaborative Research Agreement between the Registrant and Pfizer
          Inc, dated December 15, 1995.
+10.8     Collaborative Research and License Agreement between the Registrant
          and Merck & Co., Inc., dated June 13, 1996.
+10.9     Collaborative Research and License Agreement between the Registrant
          and Bristol-Myers Squibb Company and the Registrant, dated June 25,
          1996.
</TABLE>    
 
 
                                     II-3
<PAGE>
 
<TABLE>   
<CAPTION>
 EXHIBITS
 --------
 <C>      <S>
   +10.10 Supply and Services Agreement, dated as of November 1, 1995, by and
          between Terrapin Technologies, Inc. and the Registrant.
   *10.11 Screening Agreement, dated November 28, 1995, between the Registrant
          and Monsanto Company.
   +10.12 Letter Agreement, dated January 18, 1996, between Pharm-Eco
          Laboratories, Inc. and the Registrant.
   *10.13 Agreement with ArQule, Inc., dated June 4, 1996.
   *10.14 Lease Agreement between Registrant and Harry F. Stimpson III, trustee
          under the will of Harry F. Stimpson dated April 30, 1993, regarding
          24 Emily Street, Cambridge, MA., as amended by the First Amendment to
          Lease, dated September 19, 1994.
   *10.15 Form of Employee Confidentiality and Non Disclosure Agreement.
   *10.16 Master Lease Agreement between the Registrant and Comdisco, Inc.,
          dated as of August 30, 1993, as amended on February 7, 1995, and as
          further amended on February 26, 1996.
   *10.17 Series B Convertible Preferred Stock Purchase Warrant between the
          Registrant and Comdisco, Inc., dated August 30, 1993.
   *10.18 Series C Convertible Preferred Stock Purchase Warrants between the
          Registrant and Comdisco, Inc., dated February 28, 1995 and February
          26, 1996.
   *10.19 Form of Series C Convertible Preferred Stock Purchase Option issued
          to each of Dr. Paul Schimmel and Dr. Julius Rebek, Jr. in May, 1995.
   *10.20 Amended and Restated Shareholders' Rights Agreement by and among the
          Registrant and the parties signatory thereto.
    11    Computation of Income Per Share.
    23.1  Consent of Bingham, Dana & Gould LLP (included in Exhibit 5).
    23.2  Consent of Coopers & Lybrand L.L.P.
    23.3  Consent of Hamilton, Brook, Smith & Reynolds, P.C.
   *24.1  Power of Attorney (included in signature page to Registration
          Statement).
    27    Financial Data Schedule.
</TABLE>    
 
- --------
*  Previously filed.
       
+  Confidential Treatment requested as to certain portions.
 
  (b) Financial Statement Schedules:
 
  All financial statement schedules have been omitted because either they are
not required, are not applicable, or the information is otherwise set forth in
the Financial Statements and Notes thereto.
 
ITEM 17. UNDERTAKINGS
 
  Insofar as indemnification for liabilities arising under the Securities Act
of 1933 may be permitted to directors, officers and controlling persons of the
Registrant pursuant to the foregoing provisions described in Item 14 above, or
otherwise, the Registrant has been advised that in the opinion of the
Securities and Exchange Commission such indemnification is against public
policy as expressed in the Securities Act and is, therefore, unenforceable. In
the event that a claim for indemnification against such liabilities (other
than the payment by the Registrant of expenses incurred or paid by a director,
officer or controlling person of the Registrant in the successful defense of
any action, suit or proceeding) is asserted by such director, officer or
controlling person in connection with the securities being registered, the
Registrant will, unless in the opinion of its counsel the matter has been
settled by controlling precedent, submit to a court of appropriate
jurisdiction the question whether such indemnification by it is against public
policy as expressed in the Securities Act and will be governed by the final
adjudication of such issue.
 
                                     II-4
<PAGE>
 
  The undersigned registrant hereby undertakes:
 
    (1) To provide the Underwriters at the closing specified in the
  Underwriting Agreement certificates in such denominations and registered in
  such names as required by the Underwriters to permit prompt delivery to
  each purchaser.
 
    (2) That for purposes of determining any liability under the Securities
  Act of 1933, the information omitted from the form of prospectus filed as
  part of this registration statement in reliance upon Rule 430A and
  contained in a form of prospectus filed by the registrant pursuant to Rule
  424(b)(1) or (4), or 497(h) under the Securities Act shall be deemed to be
  part of this registration statement as of the time it was declared
  effective.
 
    (3) That for the purpose of determining any liability under the
  Securities Act of 1933, each post-effective amendment that contains a form
  of prospectus shall be deemed to be a new registration statement relating
  to the securities offered therein, and the offering of such securities at
  that time shall be deemed to be the initial bona fide offering thereof.
 
                                     II-5
<PAGE>
 
                                   SIGNATURES
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, AS AMENDED, THE
REGISTRANT, CUBIST PHARMACEUTICALS, INC., DULY CAUSED THIS PRE-EFFECTIVE
AMENDMENT NO. 2 TO BE SIGNED ON ITS BEHALF BY THE UNDERSIGNED, THEREUNTO DULY
AUTHORIZED, IN THE CITY OF CAMBRIDGE, COMMONWEALTH OF MASSACHUSETTS, ON THIS
17TH DAY OF SEPTEMBER, 1996.     
 
                                          Cubist Pharmaceuticals, Inc.
 
                                                   /s/ Scott M. Rocklage
                                          By: _________________________________
                                                    SCOTT M. ROCKLAGE
                                               PRESIDENT AND CHIEF EXECUTIVE
                                                          OFFICER
   
  PURSUANT TO THE REQUIREMENTS OF THE SECURITIES ACT OF 1933, THIS PRE-
EFFECTIVE AMENDMENT NO. 2 HAS BEEN SIGNED BELOW BY THE FOLLOWING PERSONS IN THE
CAPACITIES AND ON THE DATES INDICATED:     
 
              SIGNATURE                         TITLE                DATE
 
        /s/ Scott M. Rocklage           President, Chief           
- -------------------------------------    Executive Officer      September 17,
          SCOTT M. ROCKLAGE              and Director             1996     
                                         (Principal
                                         Executive Officer)
 
                  *                     Treasurer (Principal       
- -------------------------------------    Financial and          September 17,
           THOMAS A. SHEA                Accounting Officer)      1996     
 
                  *                     Chairman of the            
- -------------------------------------    Board of Directors     September 17,
           JOHN K. CLARKE                                         1996     
 
 
                                      II-6
<PAGE>
 
              SIGNATURE                         TITLE                DATE
 
                  *                     Director                   
- -------------------------------------                           September 17,
             BARRY BLOOM                                          1996     
 
                  *                     Director                   
- -------------------------------------                           September 17,
           GEORGE CONRADES                                        1996     
 
                  *                     Director                   
- -------------------------------------                           September 17,
           ELLEN M. FEENEY                                        1996     
 
                  *                     Director                   
- -------------------------------------                           September 17,
         TERRANCE G. MCGUIRE                                      1996     
 
                  *                     Director                   
- -------------------------------------                           September 17,
          JULIUS REBEK, JR                                        1996     
 
                  *                     Director                   
- -------------------------------------                           September 17,
          PAUL R. SCHIMMEL                                        1996     
 
        /s/ Scott M. Rocklage
*By: ________________________________
         SCOTT M. ROCKLAGE,
          ATTORNEY-IN-FACT
 
                                      II-7
<PAGE>
 
                                 EXHIBIT INDEX
<TABLE>   
<CAPTION>
 EXHIBITS
 --------
 <C>      <S>                                                               <C>
 *1.1     Proposed Form of Underwriting Agreement.
  3.1     Restated Certificate of Incorporation of the Registrant.
  3.2     Form of Certificate of Amendment to the Restated Certificate of
          Incorporation of the Registrant (to be filed with the Secretary
          of State of the State of Delaware prior to the effectiveness of
          the Registration Statement).
  3.3     Form of Restated Certificate of Incorporation of the Registrant
          (to be filed with the Secretary of State of the State of
          Delaware upon the closing of the Offering).
  3.4     Amended and Restated By-Laws of the Registrant, as amended to
          date.
  4.1     Specimen certificate for shares of Common Stock.
 *4.2     Description of Capital Stock (contained in the Restated
          Certificate of Incorporation of the Corporation of the
          Registrant, filed as Exhibit 3.3).
  5.1     Opinion of Bingham, Dana & Gould LLP, with respect to the
          legality of the shares being registered.
+10.1     (a) License Agreement between the Registrant and the
          Massachusetts Institute of Technology, dated November 4, 1992,
          as amended by the First Amendment, dated January 20, 1995, and
          the Second Amendment, dated May 17, 1995.
          (b) Patent License Agreement between the Registrant and the
          Massachusetts Institute of Technology, dated July 21, 1994.
+10.2     License Agreement between the Registrant and the Board of
          Trustees of the Leland Stanford Junior University, dated April
          1, 1994.
*10.3     Employment Agreement between the Registrant and Scott M.
          Rocklage, dated June 20, 1994.
*10.4     Consulting Agreement between the Registrant and Paul R.
          Schimmel, dated May 1, 1992.
*10.5     Consulting Agreement between the Registrant and Julius Rebek,
          Jr., dated May 1, 1992.
 10.6     Amended and Restated 1993 Stock Option Plan.
+10.7     Collaborative Research Agreement between the Registrant and
          Pfizer Inc, dated December 15, 1995.
+10.8     Collaborative Research and License Agreement between the
          Registrant and Merck & Co., Inc., dated June 13, 1996.
+10.9     Collaborative Research and License Agreement between the
          Registrant and Bristol-Myers Squibb Company and the Registrant,
          dated June 25, 1996.
+10.10    Supply and Services Agreement, dated as of November 1, 1995, by
          and between Terrapin Technologies, Inc. and the Registrant.
*10.11    Screening Agreement, dated November 28, 1995, between the
          Registrant and Monsanto Company.
+10.12    Letter Agreement, dated January 18, 1996, between Pharm-Eco
          Laboratories, Inc. and the Registrant.
*10.13    Agreement with ArQule, Inc., dated June 4, 1996.
*10.14    Lease Agreement between Registrant and Harry F. Stimpson III,
          trustee under the will, of Harry F. Stimpson dated April 30,
          1993, regarding 24 Emily Street, Cambridge, MA., as amended by
          the First Amendment to Lease, dated September 19, 1994.
*10.15    Form of Employee Confidentiality and Non Disclosure Agreement.
</TABLE>    
<PAGE>
 
<TABLE>   
<CAPTION>
 EXHIBITS
 --------
 <C>      <S>
  *10.16  Master Lease Agreement between the Registrant and Comdisco, Inc.,
          dated as of August 30, 1993, as amended on February 7, 1995, and as
          further amended on February 26, 1996.
  *10.17  Series B Convertible Preferred Stock Purchase Warrant between the
          Registrant and Comdisco, Inc., dated August 30, 1993.
  *10.18  Series C Convertible Preferred Stock Purchase Warrants between the
          Registrant and Comdisco, Inc., dated February 28, 1995 and February
          26, 1996.
  *10.19  Form of Series C Convertible Preferred Stock Purchase Option issued
          to each of Dr. Paul Schimmel and Dr. Julius Rebek, Jr. in May, 1995.
  *10.20  Amended and Restated Shareholders' Rights Agreement by and among the
          Registrant and the parties signatory thereto.
   11     Computation of Income Per Share.
   23.1   Consent of Bingham, Dana & Gould LLP (included in Exhibit 5).
   23.2   Consent of Coopers & Lybrand L.L.P.
   23.3   Consent of Hamilton, Brook, Smith & Reynolds, P.C.
  *24.1   Power of Attorney (included in signature page to Registration
          Statement).
   27     Financial Data Schedule.
</TABLE>    
- --------
*Previously filed.
       
+Confidential Treatment requested as to certain portions.

<PAGE>
 
                                                                     Exhibit 3.1

                     RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                          CUBIST PHARMACEUTICALS, INC.


       CUBIST PHARMACEUTICALS, INC., a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), hereby certifies that (i) the original Certificate of
Incorporation of the Corporation was filed by the Corporation with the Secretary
of State of Delaware on May 1, 1992, (ii) this Restated Certificate of
Incorporation was duly adopted in accordance with the provisions of Sections 242
and 245 of the Delaware General Corporation Law, and (iii) the Restated
Certificate of Incorporation restates, integrates and further amends the
Corporation's Certificate of Incorporation, as heretofore amended, to read in
its entirety as follows:

       FIRST.     The name of the Corporation is CUBIST PHARMACEUTICALS, INC.

       SECOND.    The address of the Corporation's registered office in the
State of Delaware is 1013 Centre Road, in the City of Wilmington, County of New
Castle.  The name of the Corporation's registered agent at such address is
Corporation Service Company.

       THIRD.     The purpose of the Corporation is to engage in any lawful act
or activity for which corporations may be organized under the General
Corporation Law of the State of Delaware.

       FOURTH.    The total number of shares of all classes of stock that the
Corporation shall have authority to issue is 95,000,000, consisting solely of:

       52,000,000 shares of common stock, $.001 par value per share ("Common
                  Stock"); and

       43,000,000 shares of preferred stock, $.001 par value per share
                  ("Preferred Stock"), of which

                  5,000,000 shares of Preferred Stock have been designated as
                  Series A Convertible Preferred Stock, $.001 par value per
                  share ("Series A Preferred Stock");

                  14,973,870 shares of Preferred Stock have been designated as
                  Series B Convertible Preferred Stock, $.001 par value per
                  share ("Series B Preferred Stock");
<PAGE>
 
                                      -2-

                  15,383,646 shares of Preferred Stock have been designated as
                  Series C Convertible Preferred Stock, $.001 par value per
                  share ("Series C Preferred Stock"); and

                  2,816,902 shares of Preferred Stock have been designated as
                  Series D Convertible Preferred Stock, $.001 par value per
                  share ("Series D Preferred Stock").


     At such time as no shares of Series A Preferred Stock, Series B Preferred
Stock, Series C Preferred Stock, Series D Preferred Stock or Parity Preferred
Stock (as defined in Section 1 below) are issued and outstanding, including
without limitation because all of such shares have been converted into shares of
Common Stock in accordance with this Restated Certificate of Incorporation, all
authorized shares of each such class and series of stock, automatically and
without further actions, shall be reclassified as authorized but unissued shares
of undesignated Preferred Stock of no particular class or series, and any and
all of such shares may thereafter be issued by the Board of Directors of the
Company in one or more series, and the terms of any such series may be
determined by the Board of Directors, as provided in Section 3 below.

     The following is a statement of the powers, designations, preferences,
privileges, and relative, participating, optional, and other special rights of
the Series A Preferred Stock, Series B Preferred Stock, Series C Preferred
Stock, Series D Preferred Stock, Parity Preferred Stock and Common Stock,
respectively:

     1.   DEFINITIONS.  The following terms shall have the respective meanings
          -----------                                                         
provided therefor below in this Section 1:

     "Applicable Adjustment Price" shall mean (i) with respect to the Series A
      ---------- ---------- -----                                             
Preferred Stock, the Series A Adjustment Price, (ii) with respect to the Series
B Preferred Stock, the Series B Adjustment Price, (iii) with respect to the
Series C Preferred Stock, the Series C Adjustment Price, (iv) with respect to
the Series D Preferred Stock, the Series D Adjustment Price and (v) with respect
to each series of Parity Preferred Stock, the Parity Preferred Stock Adjustment
Price applicable to such series of Parity Preferred Stock.

     "Applicable Conversion Rate" shall mean (i) with respect to the Series A
      ---------- ---------- ----                                             
Preferred Stock, the Series A Conversion Rate, (ii) with respect to the Series B
Preferred Stock, the Series B Conversion Rate, (iii) with respect to the Series
C Preferred Stock, the Series C Conversation Rate, (iv) with respect to the
Series D Preferred Stock, the Series D Conversion Rate and (v) with respect to
each 
<PAGE>
 
                                      -3-

series of Parity Preferred Stock, the Parity Preferred Stock Conversion Rate
applicable to such series of Parity Preferred Stock.

     "Conversion Rates" shall mean, collectively, the Series A Conversion Rate,
      ---------- -----                                                         
the Series B Conversion Rate, the Series C Conversion Rate, the Series D
Conversion Rate and the Parity Preferred Stock Conversion Rate applicable to
each series of Parity Preferred Stock.

     "Convertible Securities" shall have the meaning provided therefor in
      ----------- ----------                                             
Section 2.4(e)(i) hereof.

     "Designated Preferred Stock" shall mean the Series A Preferred Stock, the
      ---------- --------- -----                                              
Series B Preferred Stock, the Series C Preferred Stock, the Series D Preferred
Stock and the Parity Preferred Stock.

     "Original Issuance Price Per Share" shall mean (i) with respect to the
      -------- -------- ----- --- -----
Series A Preferred Stock, $0.10 per share, subject to Proportional Adjustment,
(ii) with respect to the Series B Preferred Stock, $0.50 per share, subject to
Proportional Adjustment, (iii) with respect to the Series C Preferred Stock,
$0.60 per share, subject to Proportional Adjustment, (iv) with respect to the
Series D Preferred Stock, $1.42 per share, subject to Proportional Adjustment,
and (v) with respect to each series of Parity Preferred Stock, the original
issuance price of the first share issued of such series of Parity Preferred
Stock, subject to Proportional Adjustment.

     "Parity Preferred Stock" shall mean any and all series of Preferred Stock
      ------ --------- -----                                                  
ranking pari passu with the Series A Preferred Stock, the Series B Preferred
        ---- -----                                                          
Stock, the Series C Preferred Stock and the Series D Preferred Stock, as to
dividends and liquidation preference.

     "Parity Preferred Stock Adjustment Price" shall mean, at the relevant time
      ------ --------- ----- ---------- -----
of reference thereto, the quotient obtained by dividing (i) the Original
Issuance Price Per Share for such Series of Parity Preferred Stock (without
giving effect to any Proportional Adjustment to such Original Issuance Price Per
Share) by (ii) the Parity Preferred Stock Conversion Rate in effect at such time
for such series of Parity Preferred Stock.

     "Parity Preferred Stock Conversion Rate" shall mean the rate at which
      ------ --------- ----- ---------- ----                              
outstanding shares of such series of Parity Preferred Stock may be converted
into shares of Common Stock, which rate shall be subject to adjustment from time
to time pursuant to Section 2.4(e) hereof.

     "Proportional Adjustment" shall mean a proportional or other equitable
      ------------ ----------                                              
adjustment made to the Original Issuance Price Per Share of each series of
<PAGE>
 
                                      -4-

Designated Preferred Stock upon the occurrence of a stock split, reverse stock
split, stock dividend, stock combination, reclassification or other similar
change with respect to such series of Designated Preferred Stock.

     "Permitted Shares" shall mean, collectively, (a) any shares of Common Stock
      --------- ------
or Convertible Securities issued or issuable to employees or consultants, or to
persons who were to become employees or consultants, of the Corporation pursuant
to stock option, stock incentive, stock appreciation, stock bonus or
compensation rights plans or any other employee benefit plans presently in
effect or which may hereafter be adopted by the Corporation, or pursuant to
stock option, employment, consulting, restricted stock or other agreements or
arrangements of any kind, provided, however, that in no event shall the number
                          --------  -------
of such shares of Common Stock referred to in this clause (a) exceed twenty
percent (20%) of the sum of the shares of Common Stock issued and outstanding
from time to time and the shares of Common Stock issuable upon conversion of all
series of Designated Preferred Stock; (b) up to 276,484 shares of Common Stock
issuable by the Corporation to The Massachusetts Institute of Technology ("MIT")
pursuant to that certain License Agreement, which became effective as of
November 17, 1992, between the Corporation and MIT; (c) the issuance of up to
125,833 shares of Series C Preferred Stock upon exercise of warrants issued to
Comdisco, Inc.; (d) the issuance of up to 240,000 shares of Series C Preferred
Stock upon exercise of outstanding options issued to Julius Rebek, Jr. and Paul
R. Schimmel; (e) the issuance of up to 240,500 shares of Series B Preferred
Stock issuable upon exercise of warrants issued to Comdisco, Inc.; and (f) any
shares of Common Stock or Convertible Securities issued or issuable upon
conversion of Series A Preferred Stock, Series B Preferred Stock, Series C
Preferred Stock, Series D Preferred Stock, Parity Preferred Stock or any other
Convertible Securities.

     "Series A Adjustment Price" shall mean, at the relevant time of reference
      ------ - ---------- -----                                               
thereto, the quotient obtained by dividing (i) $0.10 by (ii) the Series A
Conversion Rate in effect at such time.

     "Series A Conversion Rate" shall mean the rate at which outstanding shares
      ------ - ---------- ----
of Series A Preferred Stock may be converted into shares of Common Stock, which
rate, on the Series D Original Issuance Date, shall be equal to 1 share of
Common Stock for each share of Series A Preferred Stock and thereafter shall be
subject to adjustment from time to time pursuant to Section 2.4(e) hereof.

     "Series B Adjustment Price" shall mean, at the relevant time of reference
      ------ - ---------- -----
thereto, the quotient obtained by dividing (i) $0.50 by (ii) the Series B
Conversion Rate in effect at such time.
<PAGE>
 
                                      -5-

     "Series B Conversion Rate" shall mean the rate at which outstanding shares
      ------ - ---------- ----
of Series B Preferred Stock may be converted into shares of Common Stock, which
rate, on the Series D Original Issuance Date, shall be equal to 1 share of
Common Stock for each share of Series B Preferred Stock and thereafter shall be
subject to adjustment from time to time pursuant to Section 2.4(e) hereof.

     "Series C Adjustment Price" shall mean, at the relevant time of reference
      ------ - ---------- -----
thereto, the quotient obtained by dividing (i) $0.60 by (ii) the Series C
Conversion Rate in effect at such time.

     "Series C Conversion Rate" shall mean the rate at which outstanding shares
      ------ - ---------- ----
of Series C Preferred Stock may be converted into shares of Common Stock, which
rate, on the Series D Original Issuance Date, shall be equal to 1 share of
Common Stock for each share of Series C Preferred Stock and thereafter shall be
subject to adjustment from time to time pursuant to Section 2.4(e) hereof.

     "Series D Adjustment Price" shall mean, at the relevant time of reference
      ------ - ---------- -----
thereto, the quotient obtained by dividing (i) $1.42 by (ii) the Series D
Conversion Rate in effect at such time.

     "Series D Conversion Rate" shall mean the rate at which outstanding shares
      ------ - ---------- ----
of Series D Preferred Stock may be converted into shares of Common Stock, which
rate, on the Series D Original Issuance Date, shall be equal to 1 share of
Common Stock for each share of Series D Preferred Stock and thereafter shall be
subject to adjustment from time to time pursuant to Section 2.4(e) hereof.

     "Series D Original Issuance Date" shall mean the date of issuance by the
      -------------------------------
Corporation of the first share of Series D Preferred Stock.

     2.   SERIES A PREFERRED STOCK, SERIES B PREFERRED STOCK, SERIES C PREFERRED
          ----------------------------------------------------------------------
          STOCK, SERIES D PREFERRED STOCK AND PARITY PREFERRED STOCK
          ----------------------------------------------------------

     2.1. Voting.  Except as may be otherwise provided in this Restated
          ------
Certificate of Incorporation or by law, each series of the Designated Preferred
Stock shall vote together with all other classes and series of stock of the
Corporation as a single class on all actions to be taken by the stockholders of
the Corporation. Each share of Designated Preferred Stock shall entitle the
holder thereof to such number of votes per share on each such action as shall
equal the number of shares of Common Stock (including fractions of a share) into
which such share of Designated Preferred Stock is then convertible. The
different 
<PAGE>
 
                                      -6-

series of Designated Preferred Stock shall not be construed to constitute
different classes of stock for the purposes of voting by classes unless
expressly so provided in this Restated Certificate of Incorporation.

     2.2.  Dividends.  The holders of any series of Designated Preferred Stock
           ---------
shall be entitled to receive, for each share of such series of Designated
Preferred Stock, dividends if, when and as declared by the Board of Directors
out of funds legally available therefor; provided, however, that, so long as any
                                         --------  -------
shares of such series of Designated Preferred Stock shall be outstanding, the
Corporation shall not declare or pay any dividend upon any shares of any other
series of Designated Preferred Stock or Common Stock, unless the Corporation
shall first pay, or simultaneously therewith declare and set apart a sum
sufficient for the payment of, a dividend upon all of the outstanding shares of
such series of Designated Preferred Stock in a per share amount, computed on an
as-converted basis in the manner provided in the sentence below, equal to the
per share amount of the dividend upon Common Stock or such other series of
Designated Preferred Stock (computed on an as-converted basis in the manner
provided in the sentence below), as the case may be. For purposes hereof, the
per share amount of any dividend paid or payable upon outstanding shares of any
series of Designated Preferred Stock shall be deemed equal to the amount
obtained by dividing the dividend paid or payable upon each of such outstanding
shares of such series of Designated Preferred Stock by the number of shares of
Common Stock into which each such outstanding share of such series of Designated
Preferred Stock shall then be convertible.

     2.3.  Liquidation Preference.
           ----------- ----------

     (a)  Preference.  In the event of any liquidation, dissolution or winding
          ----------
up of the affairs of the Corporation, voluntarily or involuntarily, the holders
of outstanding shares of any series of Designated Preferred Stock shall be
entitled to receive pro rata, prior to any distribution to the holders of the
Common Stock or any other stock ranking junior to such series of Designated
Preferred Stock (collectively, "Junior Stock") but pari passu with the rights of
                                                   ---- -----
holders of outstanding shares of each other series of Designated Preferred Stock
to receive their respective liquidation preference pursuant to this Section
2.3(a), a preferential amount with respect to each share of such series of
Designated Preferred Stock equal to the sum of (i) the Original Issuance Price
Per Share for such series of Designated Preferred Stock and (ii) all dividends
and distributions, if any, then declared and unpaid on account of such share. If
upon such liquidation, dissolution or winding up, the assets of the Corporation
are insufficient (after payment of the liquidation preference of any class or
series of preferred stock ranking senior on liquidation to the Designated
Preferred Stock) to provide for the payment in full of the liquidation
preference payable with respect to each outstanding share of each series of
Designated Preferred Stock, 
<PAGE>
 
                                      -7-

such assets as are available shall be paid out pro rata among the outstanding
shares of all series of Designated Preferred Stock in proportion to the
respective amounts that would be payable in respect of such shares if the
liquidation preference payable with respect to each outstanding share of each
series of Designated Preferred Stock were paid in full. After payment or setting
apart for payment of the liquidation preference payable with respect to each
outstanding share of each series of Designated Preferred Stock, the remaining
assets of the Corporation, if any, shall be distributed among the holders of the
Junior Stock.

     (b)   Merger or Acquisition.  A consolidation or merger of the Corporation
           ------ -- -----------
with or into any other corporation or corporations (other than a merger in which
the holders of capital stock of the Corporation immediately prior to the merger
directly or indirectly beneficially own a majority of the capital stock of the
surviving corporation immediately after the merger), or a sale of all or
substantially all of the assets of the Corporation, shall be deemed to be a
liquidation, dissolution or winding up within the meaning of this Section 2.3.

     2.4.  Conversion of Designated Preferred Stock.
           ---------- -- ---------- --------- -----

     The holders of outstanding shares of any series of Designated Preferred
Stock shall have conversion rights in accordance with the following provisions:

     (a)  Right to Convert.  Outstanding shares of each series of Designated
          ----- -- -------
Preferred Stock may, at the option of the holder thereof, be converted into
shares of Common Stock of the Corporation (as such shares of Common Stock may be
constituted on the conversion date) at any time and from time to time at the
Applicable Conversion Rate for such series of Designated Preferred Stock.

     (b)  Mechanics of Conversion.  The holder of a share or shares of any
          -----------------------
series of Designated Preferred Stock may exercise the conversion right as to any
thereof by delivering to the Corporation during regular business hours, at the
principal executive offices of the Corporation or at the corporate trust office
of any transfer agent of the Corporation for the shares of such series of
Designated Preferred Stock or at such other place as may be designated by the
Corporation, the certificate or certificates for the shares to be converted,
duly endorsed or assigned in blank or to the Corporation (if required by it),
accompanied by written notice stating that the holder elects to convert such
shares and stating the name or names (with addresses) in which the certificate
or certificates for Common Stock are to be issued and by payment of any tax
which may be payable in respect of any transfer involved in the issuance and
delivery of shares in any name other than that of the holder of record on the
books of the Corporation of the shares of such series of Designated Preferred
Stock converted. Conversion shall be deemed to have been effected on the date
such delivery is made, and such date is referred to herein as the "Conversion
Date". 
<PAGE>
 
                                      -8-

As promptly as practicable after conversion, the Corporation shall issue and
deliver to or upon the written order of such holder, at such office or other
place designated by the Corporation, a certificate or certificates for the
number of full shares of Common Stock to which such holder is entitled and a
check or cash in respect of any fraction of a share as provided below. The
person in whose name the certificate or certificates for Common Stock are to be
issued shall be deemed to have become a shareholder of record on the Conversion
Date unless the transfer books of the Corporation are closed on that date, in
which event he shall be deemed to have become a shareholder of record on the
next succeeding date on which the transfer books are open, but the Applicable
Conversion Rate for the shares of the series of Designated Preferred Stock
converted shall be that in effect on the Conversion Date. No payment or
adjustment shall be made upon any conversion on account of any dividends
declared but unpaid on the shares of any series of Designated Preferred Stock
surrendered for conversion or on account of any dividends on the shares of
Common Stock issued upon such conversion.

     (c)  Mandatory Conversion.  All outstanding shares of each series of
          --------------------
Designated Preferred Stock shall be deemed automatically converted into shares
of Common Stock at the Applicable Conversion Rate for such series of Designated
Preferred Stock upon the occurrence of a closing of a public offering for the
account of the Corporation of the Common Stock of the Corporation or securities
convertible into or exchangeable for shares of Common Stock of the Corporation,
(I) where the holders of sixty percent in voting power of the shares of such
series of Designated Preferred Stock then outstanding, voting, consenting or
otherwise acting as a single class separate from the holders of all other series
or classes of capital stock of the Company, elect in writing or at a duly called
meeting of stockholders of the Corporation to effect such automatic conversion,
or (II) where the aggregate sales price of the securities included in such
public offering and in all other public offerings for the account of the
Corporation of Common Stock or securities convertible into or exchangeable for
shares of Common Stock of the Corporation closed prior thereto (before deduction
of any underwriting commissions, discounts or commissions or expenses of sale)
is at least $15,000,000 and where in such public offering the price per share of
Common Stock (or, if securities convertible into or exchangeable for Common
Stock have been sold, the aggregate sales price of such securities plus the
aggregate consideration payable to the Corporation upon the conversion or
exchange of such securities into shares of Common Stock divided by the total
number of shares of Common Stock into which such securities are convertible or
exchangeable) is not less than (i) if such closing occurs on or prior to the
first anniversary of the Series D Original Issuance Date, the amount obtained by
dividing $1.56 by the Applicable Conversion Rate for such series of Designated
Preferred Stock, as in effect prior to the closing of such public offering, or
(ii) if such closing occurs after the first anniversary of 
<PAGE>
 
                                      -9-

the Series D Original Issuance Date, the amount obtained by dividing $1.85 by
the Applicable Conversion Rate for such series of Designated Preferred Stock, as
in effect prior to the closing of such public offering. On or after the date of
the closing of such public offering, and in any event within ten days after
receipt of notice, by mail, postage prepaid from the Corporation of the
occurrence thereof, each holder of shares of any series of Designated Preferred
Stock shall surrender such holder's certificates evidencing such shares at the
principal executive offices of the Corporation or at the corporate trust office
of any transfer agent for the shares of such series of Designated Preferred
Stock or at such other place as may be designated by the Corporation, and shall
thereupon be entitled to receive certificates evidencing the number of shares of
Common Stock into which such shares of such series of Designated Preferred Stock
shall have been converted. On the date of the closing of such public offering,
each holder of shares of any series of Designated Preferred Stock shall be
deemed to have become a holder of record of the shares of Common Stock issuable
upon conversion thereof, notwithstanding that the certificates representing such
shares of such series of Designated Preferred Stock shall not have been
surrendered as provided above, that notice from the Corporation shall not have
been received by any holder of shares of Designated Preferred Stock, or that the
certificates evidencing such shares of Common Stock shall not then be actually
delivered to such person.

     (d)  Fractional Shares.  The Corporation shall not be required to issue any
          -----------------
fraction of a share upon conversion of any share or shares of any series of
Designated Preferred Stock. If more than one share of any series of Designated
Preferred Stock shall be surrendered for conversion at one time by the same
holder, the number of full shares of Common Stock issuable upon conversion
thereof shall be computed on the basis of the total number of shares of such
series of Designated Preferred Stock so surrendered. If any fractional interest
in a share of Common Stock would be deliverable upon conversion, the Corporation
shall make an adjustment therefor in cash. Adjustment in cash shall be made on
the basis of the current market price of one share of Common Stock on the
Conversion Date. A determination of the current market price made in good faith
by the Board of Directors for the purposes of this Section 2.4(d) or Section
2.4(e)(iv) hereof shall be conclusive and binding upon all the shareholders of
the Corporation.

     (e)  Conversion Rate Adjustments.  The Conversion Rates shall be subject to
          ---------------------------
the following adjustments:

          (i)  If the Corporation shall pay to the holders of its Common Stock a
     dividend in shares of Common Stock or in securities convertible into its
     Common Stock (the "Convertible Securities"), each of the Conversion Rates,
     as in effect immediately prior to the record date fixed for the
     determination of the holders of Common Stock entitled to such  
<PAGE>
 
                                     -10-


dividend, shall be increased, effective at the opening of business on the full
business day next following such record date, by multiplying such Conversion
Rate by a fraction, the numerator of which is the number of shares of Common
Stock issued and outstanding on such record date plus the number of shares of
Common Stock issued, or issuable upon conversion of the Convertible Securities
issued, in payment of such dividend and the denominator of which is the number
of shares of Common Stock issued and outstanding on such record date.

        (ii) If the Corporation shall split the outstanding shares of its Common
Stock into a greater number of shares or combine the outstanding shares of its
Common Stock into a smaller number of shares, each of the Conversion Rates, as
in effect immediately prior to such action, shall be increased in the case of a
split or decreased in the case of a combination, effective at the opening of
business on the full business day next following the day such action becomes
effective, so that each holder of shares of any series of Designated Preferred
Stock thereafter surrendered for conversion shall be entitled to receive the
number of shares of Common Stock which such holder would have been entitled to
receive as a result of such split or combination if such shares of such series
of Designated Preferred Stock had been converted immediately prior to the date
such split or combination, as the case may be, became effective.

        (iii) If the Corporation shall issue or sell options, warrants or rights
to subscribe for or purchase shares of its Common Stock, other than Permitted
Shares, at a price per share (plus the consideration per share of Common Stock,
if any, received for such options, warrants or rights) less than the Applicable
Adjustment Price with respect to any series of Designated Preferred Stock, as in
effect immediately prior to such issuance or sale, or to subscribe for or
purchase any Convertible Securities at a price per share (plus the consideration
per share of Convertible Securities, if any, received for such options, warrants
or rights) which when divided by the conversion rate applicable to those
Convertible Securities is less than the Applicable Adjustment Price with respect
to any series of Designated Preferred Stock, as in effect immediately prior to
such issuance or sale, the Applicable Conversion Rate with respect to such
series of Designated Preferred Stock, as in effect immediately prior to such
issuance or sale, shall be increased, effective at the opening of business on
the first full business day next following such issuance or sale, to an amount
determined by multiplying such Applicable Conversion Rate by a fraction the
numerator of which is the number of shares of Common Stock of the Corporation
outstanding immediately prior to said date plus the number of shares of Common
Stock issuable on exercise of 
<PAGE>
 
                                     -11-


such options, warrants or rights (or, in the case of Convertible Securities, the
number of shares of Common Stock into which the Convertible Securities issuable
on exercise of such options, warrants or rights would then be convertible) and
the denominator of which is the number of shares of Common Stock outstanding
immediately prior to said date plus the number of shares of Common Stock of the
Corporation which the aggregate subscription or purchase price for the total
number of such shares issuable on exercise of such options, warrants or rights
(including the consideration, if any, received by the Corporation for such
options, warrants or rights) would purchase at the Applicable Adjustment Price
with respect to such series of Designated Preferred Stock, as in effect
immediately prior to such issuance or sale. On the expiration of such options,
warrants or rights, the Applicable Conversion Rate with respect to any then
outstanding shares of such series of Designated Preferred Stock shall forthwith
be readjusted to the Applicable Conversion Rate for such series of Designated
Preferred Stock which would have obtained at the time of such expiration if the
adjustment made at the time such options, warrants or rights were issued or sold
had been made upon the basis of the issuance of only the number of shares of
Common Stock or Convertible Securities actually issued upon the exercise of such
options, warrants or rights, but such readjustment shall not affect any
conversion theretofore made.

        (iv) If the Corporation shall distribute to the holders of its Common
Stock any evidences of its indebtedness, or any options, warrants or rights to
subscribe for any security other than its Common Stock or Convertible
Securities, or any other assets (excluding dividends and distributions in cash
to the extent permitted by law), the Applicable Conversion Rate with respect to
each series of Designated Preferred Stock in effect immediately prior to the
record date fixed for the determination of the holders of Common Stock entitled
to such distribution shall be increased, effective at the opening of business on
the next following full business day, to an amount determined by multiplying
such Applicable Conversion Rate by a fraction the numerator of which is the
current market price of one share of Common Stock on such record date
(determined in accordance with the provisions of Section 2.4(d) hereof) and the
denominator of which is such current market price less the fair market value (as
determined by an independent appraiser selected with the approval of at least
seventy percent (70%) of the members of the Board of Directors of the
Corporation then in office, whose determination, in the absence of fraud, shall
be conclusive) of the amount of evidences of indebtedness, options, rights,
warrants or other assets (excluding cash dividends and distributions, as
aforesaid) so distributed which is applicable to one share of Common Stock.
<PAGE>
 
                                     -12-


         (v) If the Corporation shall issue shares of its Common Stock or
     Convertible Securities other than Permitted Shares and other than pursuant
     to a transaction described in Sections 2.4(e)(i) - 2,4(e)(iv) hereof, at a
     price per share of less than the Applicable Adjustment Price with respect
     to any series of Designated Preferred Stock, as in effect immediately prior
     to such issuance, (or, in the case of Convertible Securities, at a price
     per share which when divided by the conversion rate applicable thereto is
     less than the Applicable Adjustment Price with respect to any series of
     Designated Preferred Stock, as in effect immediately prior to such
     issuance), the Applicable Conversion Rate with respect to such series of
     Designated Preferred Stock, as in effect immediately prior to such
     issuance, shall be increased, effective at the opening of business on the
     next following full business day, to an amount determined by multiplying
     such Applicable Conversion Rate by a fraction the numerator of which is the
     number of shares of Common Stock of the Corporation outstanding immediately
     prior to such issuance plus the number of additional shares of Common Stock
     to be so issued (or, in the case of Convertible Securities, the number of
     additional shares of Common Stock into which the Convertible Securities to
     be so issued would be convertible) and the denominator of which is the
     number of shares of Common Stock outstanding immediately prior to such
     issuance plus the number of shares of Common Stock of the Corporation which
     the aggregate purchase price for the total number of additional shares of
     Common Stock or Convertible Securities to be so issued would purchase at
     the Applicable Adjustment Price with respect to such series of Designated
     Preferred Stock, as in effect immediately prior to such issuance.

No adjustment of the Applicable Conversion Rate with respect to any series of
Designated Preferred Stock, as provided in this Section 2.4(e), shall be made by
reason of the issuance of shares of Common Stock or Convertible Securities of
the Corporation, or options, warrants or rights to subscribe therefor, for cash,
property or services, except as provided in Sections 2.4(e)(iii) and 2.4(e)(v)
hereof.  To the extent that any shares of Common Stock or Convertible Securities
of the Corporation, or options, warrants or rights to subscribe therefor, shall
be issued for a cash consideration, the consideration received by the
Corporation therefor shall be deemed to be the amount of the cash received by
the Corporation therefor without deduction therefrom of any expenses incurred or
any underwriting commissions, discounts or concessions paid or allowed by the
Corporation in connection therewith.  In the case of the issuance of Common
Stock or Convertible Securities, or options, warrants or rights to subscribe
therefor, for a consideration all or part of which shall be property received or
services performed, the value of such property or services for the purposes of
Sections 2.4(e)(iii) and 2.4(e)(v) hereof shall be determined, 
<PAGE>
 
                                     -13-


irrespective of the accounting treatment thereof and without deduction therefrom
of any reasonable expenses incurred or any underwriting commissions, discounts
or concessions paid or allowed by the Corporation in connection therewith, by at
least seventy percent (70%) of the members of the Board of Directors of the
Corporation then in office, whose determination, in the absence of fraud, shall
be conclusive. Notwithstanding anything in this Restated Certificate of
Incorporation to the contrary, any adjustment, pursuant to the provisions of
this Section 2.4(e), to the Applicable Conversion Rate with respect to any
series of Designated Preferred Stock may be waived by the holders of sixty
percent in voting power of the shares of such series of Designated Preferred
Stock then outstanding, voting, consenting or otherwise acting as a single class
separate from the holders of all other series or classes of capital stock of the
Company.

        (f)  Adjustment for Mergers, Consolidations, Etc. In case of any
             -------------------------------------------
reclassification or change of the outstanding shares of Common Stock of the
Corporation (except a split or combination of shares) or in case of any
consolidation or merger to which the Corporation is a party (except a merger in
which the Corporation is the surviving corporation and which does not result in
any reclassification of or change in the outstanding Common Stock of the
Corporation, except a split or combination of shares as to which Section
2.4(e)(ii) is applicable) or in case of any sale or conveyance to another
corporation of all or substantially all of the property of the Corporation,
effective provision shall be made by the Corporation or by the successor or
purchasing corporation so that (A) each holder of then outstanding shares of any
series of Designated Preferred Stock shall thereafter have the right to convert
such shares into the kind and amount of stock and other securities and property
receivable upon such reclassification, change, consolidation, merger, sale or
conveyance by a holder of the number of shares of Common Stock of the
Corporation into which such shares of such series of Designated Preferred Stock
might have been converted immediately prior thereto, and (B) there shall be
subsequent adjustments of the Applicable Conversion Rate with respect to such
series of Designated Preferred Stock which shall be equivalent, as nearly as
practicable, to the adjustments provided for in Section 2.4(e) hereof. The
provisions of this Section 2.4(f) shall similarly apply to successive
reclassifications, changes, consolidations, mergers, sales or conveyances.

        (g) Taxes. The issuance of shares of Common Stock of the Corporation on
            -----    
conversion of shares of any series of Designated Preferred Stock shall be
without charge to the converting holder of such shares for any tax in respect of
the issuance of such shares of Common Stock, but the Corporation shall not be
required to pay any tax which may be payable in respect of any transfer involved
in the issuance and delivery of such shares of Common Stock in any name other
than that of the holder of record on the books of the Corporation of 
<PAGE>
 
                                     -14-


such shares of such series of Designated Preferred Stock converted, and the
Corporation shall not be required to issue or deliver any certificate for shares
of Common Stock unless and until the person requesting issuance thereof shall
have paid to the Corporation the amount of such tax or shall have established to
the satisfaction of the Corporation that such tax has been paid.

        (h) Reservation of Stock Issuable Upon Conversion. Shares of Common
            --------------------------------------------- 
Stock issued on conversion of shares of any series of Designated Preferred Stock
shall be issued as fully paid shares and shall be non-assessable by the
Corporation. The Corporation shall at all times reserve and keep available for
the purpose of effecting the conversion of shares of each series of Designated
Preferred Stock such number of its duly authorized shares of Common Stock as
shall be sufficient to effect the conversion of all outstanding shares of such
series of Designated Preferred Stock, and, to the extent necessary in order to
reserve a sufficient number of such shares of Common Stock, the Corporation
shall, subject to appropriate shareholder action, amend its Certificate of
Incorporation to increase the number of duly authorized but unissued shares of
its Common Stock.

        (i) No Reissuance of Preferred Stock. Shares of any series of Designated
            -------------------------------- 
Preferred Stock converted as provided herein shall not be reissued and the Board
of Directors shall take appropriate action from time to time to effect
reductions in the number of shares of such series of Designated Preferred Stock
which the Corporation is authorized to issue.

        (j) Notice of Adjustment. Upon any adjustment of the Applicable
            --------------------
Conversion Rate or the Applicable Adjustment Price with respect to any series of
Designated Preferred Stock, then and in each such case, the Corporation shall
give written notice thereof, by hand or registered or certified mail, postage
and charges prepaid, or by express overnight delivery, or by telecopy or telex
(in which cases, the original notice shall be sent by means reasonably intended
to result in delivery of the original notice to the recipient thereof on the
next business day) addressed to each holder of such series of Designated
Preferred Stock subject to conversion under this Section 2.4 at the address of
such holder as shown on the books of the Corporation, which notice shall state
the Applicable Conversion Rate for such series of Designated Preferred Stock
resulting from such adjustment, setting forth in reasonable detail the method
upon which such calculation is based.

        (k)  Other Notices.  In case at any time:
             -------------   

             (i)  the Corporation shall declare any dividend upon its Common
        Stock payable in cash, stock or Convertible Securities or make any other
        distribution to the holders of its Common Stock;
<PAGE>
 
                                     -15-

             (ii)   the Corporation shall offer for subscription pro rata to the
        holders of its Common Stock any additional shares of stock of any class,
        any Convertible Securities, or other rights;

             (iii)  there shall be any capital reorganization or
        reclassification of the capital stock of the Corporation, or a
        consolidation or merger of the Corporation with or into, or a sale of
        all or substantially all its assets to, another entity or entities; or

             (iv)   there shall be a voluntary or involuntary dissolution,
        liquidation or winding up of the Corporation;

then, in any one or more of said cases, the Corporation shall give, by any of
the means specified in Section 2.4(j) hereof, addressed to each holder of shares
of any series of Designated Preferred Stock at the address of such holder as
shown on the books of the Corporation, (a) at least 20 days' prior written
notice of the date on which the books of the Corporation shall close or a record
shall be taken for such dividend, distribution or subscription rights or for
determining rights to vote in respect of any such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding up and (b) in the case of any such reorganization, reclassification,
consolidation, merger, sale, dissolution, liquidation or winding up, at least 20
days' prior written notice of the date when the same shall take place.  Such
notice in accordance with the foregoing clause (a) shall also specify, in the
case of any such dividend, distribution or subscription rights, the date on
which the holders of Common Stock shall be entitled thereto and such notice in
accordance with the foregoing clause (b) shall also specify the date on which
the holders of Common Stock shall be entitled to exchange their Common Stock for
securities or other property deliverable upon such reorganization,
reclassification, consolidation, merger, sale, dissolution, liquidation or
winding up, as the case may be.

        3.   ADDITIONAL SERIES OF PREFERRED STOCK. The Board of Directors is
             ------------------------------------
hereby expressly authorized to provide for, designate and issue, out of the
authorized but unissued shares of Preferred Stock, one or more other series of
Preferred Stock in addition to the Series A Preferred Stock, Series B Preferred
Stock, Series C Preferred Stock and Series D Preferred Stock, subject to the
terms and conditions set forth herein. Before any shares of any such series are
issued, the Board of Directors shall fix, and hereby is expressly empowered to
fix, by resolution or resolutions, the following provisions of the shares of any
such series:
<PAGE>
 
                                     -16-


        (a)  the designation of such series, the number of shares to constitute
such series and the stated value thereof, if different from the par value
thereof;

        (b)  whether the shares of such series shall have voting rights or
powers, in addition to any voting rights required by law, and, if so, the terms
of such voting rights or powers, which may be full or limited;

        (c)  the dividends, if any, payable on such series, whether any such
dividends shall be cumulative, and, if so, from what dates, the conditions and
dates upon which such dividends shall be payable, the preference or relation
which such dividends shall bear to the dividends payable on any shares of stock
of any other class or series;

        (d)  whether the shares of such class or series shall be subject to
redemption by the Corporation, and, if so, the times, prices and other
conditions of such redemption;

        (e)  the amount or amounts payable with respect to shares of such class
or series upon, and the rights of the holders of such class or series in, the
voluntary or involuntary liquidation, dissolution or winding up, or upon any
distribution of the assets, of the Corporation;

        (f)  whether the shares of such class or series shall be subject to the
operation of a retirement or sinking fund and, if so, the extent to and manner
in which any such retirement or sinking fund shall be applied to the purchase or
redemption of the shares of such class or series for retirement or other
corporate purposes and the terms and provisions relative to the operation
thereof;

        (g)  whether the shares of such class or series shall be convertible
into, or exchangeable for, shares of stock of any other class or series of any
other securities and, if so, the price or prices or the rate or rates of
conversion or exchange and the method, if any, of adjusting the same, and any
other terms and conditions of conversion or exchange;

        (h)  the limitations and restrictions, if any, to be effective while any
shares of such class or series are outstanding upon the payment of dividends or
the making of other distributions on, and upon the purchase, redemption or other
acquisition by the Corporation of, the Common Stock or shares of stock of any
other class or series;

        (i)  the conditions or restrictions, if any, to be effective while any
shares of such class or series are outstanding upon the creation of indebtedness
<PAGE>
 
                                     -17-


of the Corporation or upon the issue of any additional stock, including
additional shares of such class or series or of any other class or series; and

        (j)  any other powers, designations, preferences and relative,
participating, optional or other special rights, and any qualifications,
limitations or restrictions thereof.

        The powers, designations, preferences and relative, participating,
optional or other special rights of each series of Preferred Stock, and the
qualifications, limitations or restrictions thereof, if any, may differ from
those of any and all other series at any time outstanding. The Board of
Directors is hereby expressly authorized from time to time to increase (but not
above the total number of authorized shares of Preferred Stock) or decrease (but
not below the number of shares thereof then outstanding) the number of shares of
stock of any series of Preferred Stock designated to any one or more series of
Preferred Stock pursuant to this Section 3. Different series of Preferred Stock
shall not be construed to constitute different classes of stock for purposes of
voting by classes unless expressly so provided in the resolution or resolutions
adopted by the Board of Directors creating or establishing any such series of
Preferred Stock.

        4.   COMMON STOCK
             ------------
        4.1. Increase or Decrease in Authorized Number. The number of authorized
             -----------------------------------------
shares of Common Stock may be increased or decreased (but not below the combined
number of shares thereof then outstanding and those reserved for issuance upon
conversion of the outstanding shares of all series of Designated Preferred
Stock) by the affirmative vote of the holders of the majority of the stock of
the Corporation entitled to vote, irrespective of the provisions of Section
242(b)(2) of the Delaware General Corporation Law.

        4.2. Voting Rights. Except as otherwise required by law, each holder of
             -------------
Common Stock shall have one vote in respect of each share of Common Stock held
of record on all matters submitted to a vote of stockholders of the Corporation.
Except as otherwise required by law, and subject to the voting rights provided
to the holders of any series of Preferred Stock (other than Series A Preferred
Stock, Series B Preferred Stock, Series C Preferred Stock and Series D Preferred
Stock), the holders of Common Stock and the holders of shares of Series A
Preferred Stock, Series B Preferred Stock, Series C Preferred Stock and/or
Series D Preferred Stock shall vote together as a single class on all matters
submitted to the shareholders for a vote.

        4.3. Dividends. Each share of Common Stock issued and outstanding shall
             ---------  
be identical in all respects with each other such share, and no dividends shall
be paid on any shares of Common Stock unless the same dividend is paid 
<PAGE>
 
                                     -18-


on all shares of Common Stock outstanding at the time of such payment. Except
for and subject to those rights expressly granted to the holders of Preferred
Stock and except as may be provided by the laws of the State of Delaware, the
holders of Common Stock shall have all other rights of stockholders, including,
without limitation, (a) the right to receive dividends, when and as declared by
the Board of Directors, out of assets lawfully available therefor, and (b) in
the event of any distribution of assets upon a liquidation or otherwise, the
right to receive ratably and equally all the assets and funds of the Corporation
remaining after the payment to the holders of the Preferred Stock or of any
other class or series of stock ranking senior to the Common Stock upon
liquidation of the specific preferential amounts which they are entitled to
receive upon such liquidation.

        FIFTH.    The following provisions are inserted for the management of
the business and for the conduct of the affairs of the Corporation and for
defining and regulating the powers of the Corporation and its directors and
stockholders and are in furtherance and not in limitation of the powers
conferred upon the Corporation by statute:

             (a)  The election of directors need not be by written ballot.

             (b)  The Board of Directors shall have the power and authority:

                  (1)  To adopt, amend or repeal by-laws of the Corporation,
             subject only to such limitation, if any, as may be from time to
             time imposed by law or by the by-laws; and

                  (2)  to the full extent permitted or not prohibited by law,
             and without the consent of or other action by the stockholders, to
             authorize or create mortgages, pledges or other liens or
             encumbrances upon any or all of the assets, real, personal or
             mixed, and franchises of the Corporation, including after-acquired
             property, and to exercise all of the powers of the Corporation in
             connection therewith; and

                  (3)  subject to any provision of the by-laws, to determine
             whether, to what extent, at what times and places and under what
             conditions and requisitions the accounts, books and papers of the
             Corporation (other than the stock ledger), or any of them, shall be
             open to the inspection of the stockholders, and no stockholder
             shall have any right to inspect any account, book or paper of the
             Corporation except as conferred by statute or authorized by the by-
             laws or by the Board of Directors.
<PAGE>
 
                                     -19-


        SIXTH.    No director of the Corporation shall be personally liable to
the Corporation or to any of its stockholders for monetary damages for breach of
fiduciary duty as a director, notwithstanding any provision of law imposing such
liability; provided, however, that to the extent required from time to time by
applicable law, this Article Sixth shall not eliminate or limit the liability of
a director, to the extent such liability is provided by applicable law, (i) for
any breach of the director's duty of loyalty to the Corporation or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
Title 8 of the Delaware Code, or (iv) for any transactions from which the
director derived an improper personal benefit. No amendment to or repeal of this
Article Sixth shall apply to or have any effect on the liability or alleged
liability of any director for or with respect to any acts or omissions of such
director occurring prior to the effective date of such amendment or repeal.

        SEVENTH.  Except as otherwise specifically provided in this Restated
Certificate of Incorporation, the Corporation reserves the right at any time,
and from time to time, to amend, alter, change or repeal any provision contained
in this Restated Certificate of Incorporation, and to add or insert other
provisions authorized at such time by the laws of the State of Delaware, in the
manner now or hereafter prescribed by law; and all rights, preferences and
privileges of whatsoever nature conferred upon stockholders, directors or any
other persons whomsoever by and pursuant to this Restated Certificate of
Incorporation, in its present form or as hereafter amended, are granted subject
to the rights reserved in this Article Seventh.

        IN WITNESS WHEREOF, the Corporation has caused this Restated Certificate
of Incorporation to be signed by its President and attested by its Secretary
this _____ day of June, 1996.

                                                 CUBIST PHARMACEUTICALS, INC.



                                                 By
                                                   ----------------------
                                                   Scott M. Rocklage,
                                                   President

ATTEST:


- --------------------------
Justin P. Morreale,
Secretary

<PAGE>
 
                                                                     EXHIBIT 3.2


                            CERTIFICATE OF AMENDMENT
                                       TO
                     RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                          CUBIST PHARMACEUTICALS, INC.


           CUBIST PHARMACEUTICALS, INC., a corporation organized and existing 
under and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), hereby certifies that:
      
           FIRST.     The Restated Certificate of Incorporation of the 
Corporation is hereby amended by deleting in its entirety Articles FOURTH,
FIFTH, SIXTH and SEVENTH thereof and by substituting in lieu thereof the
following new Articles FOURTH, FIFTH, SIXTH, SEVENTH, EIGHTH, NINETH, TENTH and
ELEVENTH:


          "FOURTH.  The total number of shares of all classes of stock that the
     Corporation shall have authority to issue is 95,000,000, consisting solely
     of:
    
     25,000,000  shares of common stock, $.001 par value per share ("Common
     Stock"); and
    
     43,000,000  shares of preferred stock, $.001 par value per share
     ("Preferred Stock"), of which
    
          5,000,000 shares of Preferred Stock have been designated as Series A
     Convertible Preferred Stock, $.001 par value per share ("Series A Preferred
     Stock");
    
          14,973,870 shares of Preferred Stock have been designated as Series B
     Convertible Preferred Stock, $.001 par value per share ("Series B Preferred
     Stock");
    
          15,383,646 shares of Preferred Stock have been designated as Series C
     Convertible Preferred Stock, $.001 par value per share ("Series C Preferred
     Stock"); and
    
          2,816,902 shares of Preferred Stock have been designated as Series D
     Convertible Preferred Stock, $.001 par value per share ("Series D Preferred
     Stock").
<PAGE>
 
                                     - 2 -


          At such time as no shares of Series A Preferred Stock, Series B 
     Preferred Stock, Series C Preferred Stock, Series D Preferred Stock or
     Parity Preferred Stock (as defined in Section 1 below) are issued and
     outstanding, including without limitation because all of such shares have
     been converted into shares of Common Stock in accordance with this Restated
     Certificate of Incorporation, all authorized shares of each such class and
     series of stock, automatically and without further actions, shall be
     reclassified as authorized but unissued shares of undesignated Preferred
     Stock of no particular class or series, and any and all of such shares may
     thereafter be issued by the Board of Directors of the Company in one or
     more series, and the terms of any such series may be determined by the
     Board of Directors, as provided in Section 3 below.
    
          The following is a statement of the powers, designations, preferences,
     privileges, and relative, participating, optional, and other special rights
     of the Series A Preferred Stock, Series B Preferred Stock, Series C
     Preferred Stock, Series D Preferred Stock, Parity Preferred Stock and
     Common Stock, respectively:
     
          1.  DEFINITIONS.  The following terms shall have the respective 
              -----------                                                
     meanings provided therefor below in this Section 1:
    
          "Applicable Adjustment Price" shall mean (i) with respect to the 
           ---------- ---------- -----                                    
     Series A Preferred Stock, the Series A Adjustment Price, (ii) with respect
     to the Series B Preferred Stock, the Series B Adjustment Price, (iii) with
     respect to the Series C Preferred Stock, the Series C Adjustment Price,
     (iv) with respect to the Series D Preferred Stock, the Series D Adjustment
     Price and (v) with respect to each series of Parity Preferred Stock, the
     Parity Preferred Stock Adjustment Price applicable to such series of Parity
     Preferred Stock.
     
         "Applicable Conversion Rate" shall mean (i) with respect to the Series
          ---------- ---------- ----                                           
     A Preferred Stock, the Series A Conversion Rate, (ii) with respect to the
     Series B Preferred Stock, the Series B Conversion Rate, (iii) with respect
     to the Series C Preferred Stock, the Series C Conversation Rate, (iv) with
     respect to the Series D Preferred Stock, the Series D Conversion Rate and
     (v) with respect to each series of Parity Preferred Stock, the Parity
     Preferred Stock Conversion Rate applicable to such series of Parity
     Preferred Stock.
<PAGE>
 
                                          - 3 -
    
     
          "Conversion Rates" shall mean, collectively, the Series A Conversion 
           ---------- -----                                                   
     Rate, the Series B Conversion Rate, the Series C Conversion Rate, the
     Series D Conversion Rate and the Parity Preferred Stock Conversion Rate
     applicable to each series of Parity Preferred Stock.
     
          "Convertible Securities" shall have the meaning provided therefor in
           ----------- ----------                                             
     Section 2.4(e)(i) hereof.
    
          "Designated Preferred Stock" shall mean the Series A Preferred Stock,
           ---------- --------- -----                                          
     the Series B Preferred Stock, the Series C Preferred Stock, the Series D
     Preferred Stock and the Parity Preferred Stock.
     
         "Original Issuance Price Per Share" shall mean (i) with respect to the
           -------- -------- ----- --- -----                                    
     Series A Preferred Stock, $0.10 per share, subject to Proportional
     Adjustment, (ii) with respect to the Series B Preferred Stock, $0.50 per
     share, subject to Proportional Adjustment, (iii) with respect to the Series
     C Preferred Stock, $0.60 per share, subject to Proportional Adjustment,
     (iv) with respect to the Series D Preferred Stock, $1.42 per share, subject
     to Proportional Adjustment, and (v) with respect to each series of Parity
     Preferred Stock, the original issuance price of the first share issued of
     such series of Parity Preferred Stock, subject to Proportional Adjustment.
     
          "Parity Preferred Stock" shall mean any and all series of Preferred 
           ------ --------- -----                                            
     Stock ranking pari passu with the Series A Preferred Stock, the Series B 
                   ---- -----                                                
     Preferred Stock, the Series C Preferred Stock and the Series D Preferred
     Stock, as to dividends and liquidation preference.
     
          "Parity Preferred Stock Adjustment Price" shall mean, at the relevant
          ------ --------- ----- ---------- -----                             
     time of reference thereto, the quotient obtained by dividing (i) the
     Original Issuance Price Per Share for such Series of Parity Preferred Stock
     (without giving effect to any Proportional Adjustment to such Original
     Issuance Price Per Share) by (ii) the Parity Preferred Stock Conversion
     Rate in effect at such time for such series of Parity Preferred Stock.
     
          "Parity Preferred Stock Conversion Rate" shall mean the rate at which
           ------ --------- ----- ---------- ----                              
     outstanding shares of such series of Parity Preferred Stock may be
     converted into shares of Common Stock, which rate shall be subject to
     adjustment from time to time pursuant to Section 2.4(e) hereof.
<PAGE>
 
                                         - 4 -
     
     
          "Proportional Adjustment" shall mean a proportional or other equitable
          ------------ ----------                                              
     adjustment made to the Original Issuance Price Per Share of each series of
     Designated Preferred Stock upon the occurrence of a stock split, reverse
     stock split, stock dividend, stock combination, reclassification or other
     similar change with respect to such series of Designated Preferred Stock.
     
          "Permitted Shares" shall mean, collectively, (a) any shares of Common
          --------- ------                                                    
     Stock or Convertible Securities issued or issuable to employees or
     consultants, or to persons who were to become employees or consultants, of
     the Corporation pursuant to stock option, stock incentive, stock
     appreciation, stock bonus or compensation rights plans or any other
     employee benefit plans presently in effect or which may hereafter be
     adopted by the Corporation, or pursuant to stock option, employment,
     consulting, restricted stock or other agreements or arrangements of any
     kind, provided, however, that in no event shall the number of such shares 
           --------  ------- 
     of Common Stock referred to in this clause (a) exceed [twenty percent
     (20%)] of the sum of the shares of Common Stock issued and outstanding from
     time to time and the shares of Common Stock issuable upon conversion of all
     series of Designated Preferred Stock; (b) up to 276,484 shares of Common
     Stock issuable by the Corporation to The Massachusetts Institute of
     Technology ("MIT") pursuant to that certain License Agreement, which became
     effective as of November 17, 1992, between the Corporation and MIT; (c) the
     issuance of up to 125,833 shares of Series C Preferred Stock upon exercise
     of warrants issued to Comdisco, Inc.; (d) the issuance of up to 240,000
     shares of Series C Preferred Stock upon exercise of outstanding options
     issued to Julius Rebek, Jr. and Paul R. Schimmel; (e) the issuance of up to
     240,500 shares of Series B Preferred Stock issuable upon exercise of
     warrants issued to Comdisco, Inc.; and (f) any shares of Common Stock or
     Convertible Securities issued or issuable upon conversion of Series A
     Preferred Stock, Series B Preferred Stock, Series C Preferred Stock, Series
     D Preferred Stock, Parity Preferred Stock or any other Convertible
     Securities.
     
          "Series A Adjustment Price" shall mean, at the relevant time of 
           ------ - ---------- -----                                     
     reference thereto, the quotient obtained by dividing (i) $0.10 by (ii) the
     Series A Conversion Rate in effect at such time.
     
          "Series A Conversion Rate" shall mean the rate at which outstanding 
           ------ - ---------- ----                                          
     shares of Series A Preferred Stock may be converted 
<PAGE>
 
                                          - 5 -
     
     
     into shares of Common Stock, which rate, on the Series D Original Issuance
     Date, shall be equal to 1 share of Common Stock for each share of Series A
     Preferred Stock and thereafter shall be subject to adjustment from time to
     time pursuant to Section 2.4(e) hereof.
     
          "Series B Adjustment Price" shall mean, at the relevant time of 
           ------ - ---------- -----                                     
     reference thereto, the quotient obtained by dividing (i) $0.50 by (ii) the
     Series B Conversion Rate in effect at such time.
     
          "Series B Conversion Rate" shall mean the rate at which outstanding 
           ------ - ---------- ----                                          
     shares of Series B Preferred Stock may be converted into shares of Common
     Stock, which rate, on the Series D Original Issuance Date, shall be equal
     to 1 share of Common Stock for each share of Series B Preferred Stock and
     thereafter shall be subject to adjustment from time to time pursuant to
     Section 2.4(e) hereof.
     
          "Series C Adjustment Price" shall mean, at the relevant time of 
           ------ - ---------- -----                                     
     reference thereto, the quotient obtained by dividing (i) $0.60 by (ii) the
     Series C Conversion Rate in effect at such time.
     
          "Series C Conversion Rate" shall mean the rate at which outstanding
           ------ - ---------- ----                                          
      shares of Series C Preferred Stock may be converted into shares of Common
     Stock, which rate, on the Series D Original Issuance Date, shall be equal
     to 1 share of Common Stock for each share of Series C Preferred Stock and
     thereafter shall be subject to adjustment from time to time pursuant to
     Section 2.4(e) hereof.
     
          "Series D Adjustment Price" shall mean, at the relevant time of
           ------ - ---------- -----                                     
     reference thereto, the quotient obtained by dividing (i) $1.42 by (ii) the
     Series D Conversion Rate in effect at such time.

          "Series D Conversion Rate" shall mean the rate at which outstanding 
           ------ - ---------- ----                                          
     shares of Series D Preferred Stock may be converted into shares of Common
     Stock, which rate, on the Series D Original Issuance Date, shall be equal
     to 1 share of Common Stock for each share of Series D Preferred Stock and
     thereafter shall be subject to adjustment from time to time pursuant to
     Section 2.4(e) hereof.
     
          "Series D Original Issuance Date" shall mean the date of issuance by
           ------ - -------- -------- ----                                    
     the Corporation of the first share of Series D Preferred Stock.
<PAGE>
 
                                          - 6 -
     
     
     2. SERIES A PREFERRED STOCK, SERIES B PREFERRED STOCK, SERIES C PREFERRED
        ----------------------------------------------------------------------
     STOCK, SERIES D PREFERRED STOCK AND PARITY PREFERRED STOCK
     ----------------------------------------------------------
    
          2.1.  Voting.  Except as may be otherwise provided in this Restated
                ------                                                       
     Certificate of Incorporation or by law, each series of the Designated
     Preferred Stock shall vote together with all other classes and series of
     stock of the Corporation as a single class on all actions to be taken by
     the stockholders of the Corporation. Each share of Designated Preferred
     Stock shall entitle the holder thereof to such number of votes per share on
     each such action as shall equal the number of shares of Common Stock
     (including fractions of a share) into which such share of Designated
     Preferred Stock is then convertible. The different series of Designated
     Preferred Stock shall not be construed to constitute different classes of
     stock for the purposes of voting by classes unless expressly so provided in
     this Restated Certificate of Incorporation.
     
          2.2.  Dividends.  The holders of any series of Designated Preferred
                ---------                                                    
      Stock shall be entitled to receive, for each share of such series of
     Designated Preferred Stock, dividends if, when and as declared by the Board
     of Directors out of funds legally available therefor; provided, however,
                                                           --------  -------
     that, so long as any shares of such series of Designated Preferred Stock
     shall be outstanding, the Corporation shall not declare or pay any dividend
     upon any shares of any other series of Designated Preferred Stock or Common
     Stock, unless the Corporation shall first pay, or simultaneously therewith
     declare and set apart a sum sufficient for the payment of, a dividend upon
     all of the outstanding shares of such series of Designated Preferred Stock
     in a per share amount, computed on an as-converted basis in the manner
     provided in the sentence below, equal to the per share amount of the
     dividend upon Common Stock or such other series of Designated Preferred
     Stock (computed on an as-converted basis in the manner provided in the
     sentence below), as the case may be. For purposes hereof, the per share
     amount of any dividend paid or payable upon outstanding shares of any
     series of Designated Preferred Stock shall be deemed equal to the amount
     obtained by dividing the dividend paid or payable upon each of such
     outstanding shares of such series of Designated Preferred Stock by the
     number of shares of Common Stock into which each such outstanding share of
     such series of Designated Preferred Stock shall then be convertible. 
<PAGE>
 
                                          - 7 -
    
     
          2.3.  Liquidation Preference.
               ----------- ---------- 
     
          (a) Preference.  In the event of any liquidation, dissolution or 
              ----------                                                  
     winding up of the affairs of the Corporation, voluntarily or involuntarily,
     the holders of outstanding shares of any series of Designated Preferred
     Stock shall be entitled to receive pro rata, prior to any distribution to
     the holders of the Common Stock or any other stock ranking junior to such
     series of Designated Preferred Stock (collectively, "Junior Stock") but
     pari passu with the rights of holders of outstanding shares of each other 
     ---- -----
     series of Designated Preferred Stock to receive their respective
     liquidation preference pursuant to this Section 2.3(a), a preferential
     amount with respect to each share of such series of Designated Preferred
     Stock equal to the sum of (i) the Original Issuance Price Per Share for
     such series of Designated Preferred Stock and (ii) all dividends and
     distributions, if any, then declared and unpaid on account of such share.
     If upon such liquidation, dissolution or winding up, the assets of the
     Corporation are insufficient (after payment of the liquidation preference
     of any class or series of preferred stock ranking senior on liquidation to
     the Designated Preferred Stock) to provide for the payment in full of the
     liquidation preference payable with respect to each outstanding share of
     each series of Designated Preferred Stock, such assets as are available
     shall be paid out pro rata among the outstanding shares of all series of
     Designated Preferred Stock in proportion to the respective amounts that
     would be payable in respect of such shares if the liquidation preference
     payable with respect to each outstanding share of each series of Designated
     Preferred Stock were paid in full. After payment or setting apart for
     payment of the liquidation preference payable with respect to each
     outstanding share of each series of Designated Preferred Stock, the
     remaining assets of the Corporation, if any, shall be distributed among the
     holders of the Junior Stock.
     
          (b) Merger or Acquisition.  A consolidation or merger of the 
              ------ -- -----------                                   
     Corporation with or into any other corporation or corporations (other than
     a merger in which the holders of capital stock of the Corporation
     immediately prior to the merger directly or indirectly beneficially own a
     majority of the capital stock of the surviving corporation immediately
     after the merger), or a sale of all or substantially all of the assets of
     the Corporation, shall be deemed to be a liquidation, dissolution or
     winding up within the meaning of this Section 2.3. 
<PAGE>
 
                                     - 8 -


          2.4.  Conversion of Designated Preferred Stock.
                ---------- -- -------------------------- 
     
         The holders of outstanding shares of any series of Designated 
     Preferred Stock shall have conversion rights in accordance with the
     following provisions:
     
         (a) Right to Convert.  Outstanding shares of each series of Designated
              ----- -- -------                                                  
     Preferred Stock may, at the option of the holder thereof, be converted into
     shares of Common Stock of the Corporation (as such shares of Common Stock
     may be constituted on the conversion date) at any time and from time to
     time at the Applicable Conversion Rate for such series of Designated
     Preferred Stock.
     
         (b) Mechanics of Conversion.  The holder of a share or shares of any
              -----------------------                                         
     series of Designated Preferred Stock may exercise the conversion right as
     to any thereof by delivering to the Corporation during regular business
     hours, at the principal executive offices of the Corporation or at the
     corporate trust office of any transfer agent of the Corporation for the
     shares of such series of Designated Preferred Stock or at such other place
     as may be designated by the Corporation, the certificate or certificates
     for the shares to be converted, duly endorsed or assigned in blank or to
     the Corporation (if required by it), accompanied by written notice stating
     that the holder elects to convert such shares and stating the name or names
     (with addresses) in which the certificate or certificates for Common Stock
     are to be issued and by payment of any tax which may be payable in respect
     of any transfer involved in the issuance and delivery of shares in any name
     other than that of the holder of record on the books of the Corporation of
     the shares of such series of Designated Preferred Stock converted.
     Conversion shall be deemed to have been effected on the date such delivery
     is made, and such date is referred to herein as the "Conversion Date". As
     promptly as practicable after conversion, the Corporation shall issue and
     deliver to or upon the written order of such holder, at such office or
     other place designated by the Corporation, a certificate or certificates
     for the number of full shares of Common Stock to which such holder is
     entitled and a check or cash in respect of any fraction of a share as
     provided below. The person in whose name the certificate or certificates
     for Common Stock are to be issued shall be deemed to have become a
     shareholder of record on the Conversion Date unless the transfer books of
     the Corporation are closed on that date, in which event he shall be deemed
     to have become a shareholder of record on the next succeeding date on which
     the transfer books are open, but the Applicable Conversion Rate for the
     shares of the
<PAGE>
 
                                          - 9 -
     
     
     series of Designated Preferred Stock converted shall be that in effect on
     the Conversion Date. No payment or adjustment shall be made upon any
     conversion on account of any dividends declared but unpaid on the shares of
     any series of Designated Preferred Stock surrendered for conversion or on
     account of any dividends on the shares of Common Stock issued upon such
     conversion.
     
          (c) Mandatory Conversion.  All outstanding shares of each series of
              --------------------                                           
     Designated Preferred Stock shall be deemed automatically converted into
     shares of Common Stock at the Applicable Conversion Rate for such series of
     Designated Preferred Stock upon the occurrence of a closing of a public
     offering for the account of the Corporation of the Common Stock of the
     Corporation or securities convertible into or exchangeable for shares of
     Common Stock of the Corporation, (I) where the holders of sixty percent in
     voting power of the shares of such series of Designated Preferred Stock
     then outstanding, voting, consenting or otherwise acting as a single class
     separate from the holders of all other series or classes of capital stock
     of the Company, elect in writing or at a duly called meeting of
     stockholders of the Corporation to effect such automatic conversion, or
     (II) where the aggregate sales price of the securities included in such
     public offering and in all other public offerings for the account of the
     Corporation of Common Stock or securities convertible into or exchangeable
     for shares of Common Stock of the Corporation closed prior thereto (before
     deduction of any underwriting commissions, discounts or commissions or
     expenses of sale) is at least $15,000,000 and where in such public offering
     the price per share of Common Stock (or, if securities convertible into or
     exchangeable for Common Stock have been sold, the aggregate sales price of
     such securities plus the aggregate consideration payable to the Corporation
     upon the conversion or exchange of such securities into shares of Common
     Stock divided by the total number of shares of Common Stock into which such
     securities are convertible or exchangeable) is not less than (i) if such
     closing occurs on or prior to the first anniversary of the Series D
     Original Issuance Date, the amount obtained by dividing $1.56 by the
     Applicable Conversion Rate for such series of Designated Preferred Stock,
     as in effect prior to the closing of such public offering, or (ii) if such
     closing occurs after the first anniversary of the Series D Original
     Issuance Date, the amount obtained by dividing $1.85 by the Applicable
     Conversion Rate for such series of Designated Preferred Stock, as in effect
     prior to the closing of such public offering. On or after the date of the
     closing of such public offering, and in any event within ten days after
     receipt of notice, by mail, postage prepaid from the Corporation of the
<PAGE>
 
                                         - 10 -
    
     
     occurrence thereof, each holder of shares of any series of Designated
     Preferred Stock shall surrender such holder's certificates evidencing such
     shares at the principal executive offices of the Corporation or at the
     corporate trust office of any transfer agent for the shares of such series
     of Designated Preferred Stock or at such other place as may be designated
     by the Corporation, and shall thereupon be entitled to receive certificates
     evidencing the number of shares of Common Stock into which such shares of
     such series of Designated Preferred Stock shall have been converted. On the
     date of the closing of such public offering, each holder of shares of any
     series of Designated Preferred Stock shall be deemed to have become a
     holder of record of the shares of Common Stock issuable upon conversion
     thereof, notwithstanding that the certificates representing such shares of
     such series of Designated Preferred Stock shall not have been surrendered
     as provided above, that notice from the Corporation shall not have been
     received by any holder of shares of Designated Preferred Stock, or that the
     certificates evidencing such shares of Common Stock shall not then be
     actually delivered to such person.
     
          (d) Fractional Shares.  The Corporation shall not be required to
              -----------------                                                 
     issue any fraction of a share upon conversion of any share or shares of any
     series of Designated Preferred Stock. If more than one share of any series
     of Designated Preferred Stock shall be surrendered for conversion at one
     time by the same holder, the number of full shares of Common Stock issuable
     upon conversion thereof shall be computed on the basis of the total number
     of shares of such series of Designated Preferred Stock so surrendered. If
     any fractional interest in a share of Common Stock would be deliverable
     upon conversion, the Corporation shall make an adjustment therefor in cash.
     Adjustment in cash shall be made on the basis of the current market price
     of one share of Common Stock on the Conversion Date. A determination of the
     current market price made in good faith by the Board of Directors for the
     purposes of this Section 2.4(d) or Section 2.4(e)(iv) hereof shall be
     conclusive and binding upon all the shareholders of the Corporation.
     
          (e) Conversion Rate Adjustments.  The Conversion Rates shall be
              ---------------------------                                
     subject to the following adjustments:
     
          (i) If the Corporation shall pay to the holders of its Common Stock a
     dividend in shares of Common Stock or in securities convertible into its
     Common Stock (the "Convertible Securities"), each of the Conversion Rates,
     as in effect immediately 
<PAGE>
 
                                         - 11 -
    
     
     prior to the record date fixed for the determination of the holders of
     Common Stock entitled to such dividend, shall be increased, effective at
     the opening of business on the full business day next following such record
     date, by multiplying such Conversion Rate by a fraction, the numerator of
     which is the number of shares of Common Stock issued and outstanding on
     such record date plus the number of shares of Common Stock issued, or
     issuable upon conversion of the Convertible Securities issued, in payment
     of such dividend and the denominator of which is the number of shares of
     Common Stock issued and outstanding on such record date.
     
         (ii) If the Corporation shall split the outstanding shares of its
     Common Stock into a greater number of shares or combine the outstanding
     shares of its Common Stock into a smaller number of shares, each of the
     Conversion Rates, as in effect immediately prior to such action, shall be
     increased in the case of a split or decreased in the case of a combination,
     effective at the opening of business on the full business day next
     following the day such action becomes effective, so that each holder of
     shares of any series of Designated Preferred Stock thereafter surrendered
     for conversion shall be entitled to receive the number of shares of Common
     Stock which such holder would have been entitled to receive as a result of
     such split or combination if such shares of such series of Designated
     Preferred Stock had been converted immediately prior to the date such split
     or combination, as the case may be, became effective.
     
         (iii)  If the Corporation shall issue or sell options, warrants or
     rights to subscribe for or purchase shares of its Common Stock, other than
     Permitted Shares, at a price per share (plus the consideration per share of
     Common Stock, if any, received for such options, warrants or rights) less
     than the Applicable Adjustment Price with respect to any series of
     Designated Preferred Stock, as in effect immediately prior to such issuance
     or sale, or to subscribe for or purchase any Convertible Securities at a
     price per share (plus the consideration per share of Convertible
     Securities, if any, received for such options, warrants or rights) which
     when divided by the conversion rate applicable to those Convertible
     Securities is less than the Applicable Adjustment Price with respect to any
     series of Designated Preferred Stock, as in effect immediately prior to
     such issuance or sale, the Applicable Conversion Rate with respect to such
     series of Designated Preferred Stock, as in effect immediately prior to
     such issuance or sale, shall be increased, effective at the opening of
     business on the first full business day next following such issuance or
     sale, to an amount determined by multiplying such 
<PAGE>
 
                                    - 12 -


     Applicable Conversion Rate by a fraction the numerator of which is the
     number of shares of Common Stock of the Corporation outstanding immediately
     prior to said date plus the number of shares of Common Stock issuable on
     exercise of such options, warrants or rights (or, in the case of
     Convertible Securities, the number of shares of Common Stock into which the
     Convertible Securities issuable on exercise of such options, warrants or
     rights would then be convertible) and the denominator of which is the
     number of shares of Common Stock outstanding immediately prior to said date
     plus the number of shares of Common Stock of the Corporation which the
     aggregate subscription or purchase price for the total number of such
     shares issuable on exercise of such options, warrants or rights (including
     the consideration, if any, received by the Corporation for such options,
     warrants or rights) would purchase at the Applicable Adjustment Price with
     respect to such series of Designated Preferred Stock, as in effect
     immediately prior to such issuance or sale. On the expiration of such
     options, warrants or rights, the Applicable Conversion Rate with respect to
     any then outstanding shares of such series of Designated Preferred Stock
     shall forthwith be readjusted to the Applicable Conversion Rate for such
     series of Designated Preferred Stock which would have obtained at the time
     of such expiration if the adjustment made at the time such options,
     warrants or rights were issued or sold had been made upon the basis of the
     issuance of only the number of shares of Common Stock or Convertible
     Securities actually issued upon the exercise of such options, warrants or
     rights, but such readjustment shall not affect any conversion theretofore
     made.
               (iv) If the Corporation shall distribute to the holders of its 
     Common Stock any evidences of its indebtedness, or any options, warrants or
     rights to subscribe for any security other than its Common Stock or
     Convertible Securities, or any other assets (excluding dividends and
     distributions in cash to the extent permitted by law), the Applicable
     Conversion Rate with respect to each series of Designated Preferred Stock
     in effect immediately prior to the record date fixed for the determination
     of the holders of Common Stock entitled to such distribution shall be
     increased, effective at the opening of business on the next following full
     business day, to an amount determined by multiplying such Applicable
     Conversion Rate by a fraction the numerator of which is the current market
     price of one share of Common Stock on such record date (determined in
     accordance with the provisions of Section 2.4(d) hereof) and the
     denominator of which is such current market price less the fair market
     value (as determined by an independent 
<PAGE>
 
                                         - 13 -
     
    
     appraiser selected with the approval of at least seventy percent (70%) of
     the members of the Board of Directors of the Corporation then in office,
     whose determination, in the absence of fraud, shall be conclusive) of the
     amount of evidences of indebtedness, options, rights, warrants or other
     assets (excluding cash dividends and distributions, as aforesaid) so
     distributed which is applicable to one share of Common Stock.
     
          (v) If the Corporation shall issue shares of its Common Stock or
     Convertible Securities other than Permitted Shares and other than pursuant
     to a transaction described in Sections 2.4(e)(i) - 2,4(e)(iv) hereof, at a
     price per share of less than the Applicable Adjustment Price with respect
     to any series of Designated Preferred Stock, as in effect immediately prior
     to such issuance, (or, in the case of Convertible Securities, at a price
     per share which when divided by the conversion rate applicable thereto is
     less than the Applicable Adjustment Price with respect to any series of
     Designated Preferred Stock, as in effect immediately prior to such
     issuance), the Applicable Conversion Rate with respect to such series of
     Designated Preferred Stock, as in effect immediately prior to such
     issuance, shall be increased, effective at the opening of business on the
     next following full business day, to an amount determined by multiplying
     such Applicable Conversion Rate by a fraction the numerator of which is the
     number of shares of Common Stock of the Corporation outstanding immediately
     prior to such issuance plus the number of additional shares of Common Stock
     to be so issued (or, in the case of Convertible Securities, the number of
     additional shares of Common Stock into which the Convertible Securities to
     be so issued would be convertible) and the denominator of which is the
     number of shares of Common Stock outstanding immediately prior to such
     issuance plus the number of shares of Common Stock of the Corporation which
     the aggregate purchase price for the total number of additional shares of
     Common Stock or Convertible Securities to be so issued would purchase at
     the Applicable Adjustment Price with respect to such series of Designated
     Preferred Stock, as in effect immediately prior to such issuance.
     
     No adjustment of the Applicable Conversion Rate with respect to any series
     of Designated Preferred Stock, as provided in this Section 2.4(e), shall be
     made by reason of the issuance of shares of Common Stock or Convertible
     Securities of the Corporation, or options, warrants or rights to subscribe
     therefor, for cash, property or services, except as provided in Sections
     2.4(e)(iii) and 2.4(e)(v)
      
<PAGE>
 
                                         - 14 -
     
    
     hereof. To the extent that any shares of Common Stock or Convertible
     Securities of the Corporation, or options, warrants or rights to subscribe
     therefor, shall be issued for a cash consideration, the consideration
     received by the Corporation therefor shall be deemed to be the amount of
     the cash received by the Corporation therefor without deduction therefrom
     of any expenses incurred or any underwriting commissions, discounts or
     concessions paid or allowed by the Corporation in connection therewith. In
     the case of the issuance of Common Stock or Convertible Securities, or
     options, warrants or rights to subscribe therefor, for a consideration all
     or part of which shall be property received or services performed, the
     value of such property or services for the purposes of Sections 2.4(e)(iii)
     and 2.4(e)(v) hereof shall be determined, irrespective of the accounting
     treatment thereof and without deduction therefrom of any reasonable
     expenses incurred or any underwriting commissions, discounts or concessions
     paid or allowed by the Corporation in connection therewith, by at least
     seventy percent (70%) of the members of the Board of Directors of the
     Corporation then in office, whose determination, in the absence of fraud,
     shall be conclusive. Notwithstanding anything in this Restated Certificate
     of Incorporation to the contrary, any adjustment, pursuant to the
     provisions of this Section 2.4(e), to the Applicable Conversion Rate with
     respect to any series of Designated Preferred Stock may be waived by the
     holders of sixty percent in voting power of the shares of such series of
     Designated Preferred Stock then outstanding, voting, consenting or
     otherwise acting as a single class separate from the holders of all other
     series or classes of capital stock of the Company.
     
          (f) Adjustment for Mergers, Consolidations, Etc.  In case of any
              -------------------------------------------                 
     reclassification or change of the outstanding shares of Common Stock of the
     Corporation (except a split or combination of shares) or in case of any
     consolidation or merger to which the Corporation is a party (except a
     merger in which the Corporation is the surviving corporation and which does
     not result in any reclassification of or change in the outstanding Common
     Stock of the Corporation, except a split or combination of shares as to
     which Section 2.4(e)(ii) is applicable) or in case of any sale or
     conveyance to another corporation of all or substantially all of the
     property of the Corporation, effective provision shall be made by the
     Corporation or by the successor or purchasing corporation so that (A) each
     holder of then outstanding shares of any series of Designated Preferred
     Stock shall thereafter have the right to convert such shares into the kind
     and amount of stock and other securities and property receivable
<PAGE>
 
                                    - 15 -


     upon such reclassification, change, consolidation, merger, sale or
     conveyance by a holder of the number of shares of Common Stock of the
     Corporation into which such shares of such series of Designated Preferred
     Stock might have been converted immediately prior thereto, and (B) there
     shall be subsequent adjustments of the Applicable Conversion Rate with
     respect to such series of Designated Preferred Stock which shall be
     equivalent, as nearly as practicable, to the adjustments provided for in
     Section 2.4(e) hereof. The provisions of this Section 2.4(f) shall
     similarly apply to successive reclassifications, changes, consolidations,
     mergers, sales or conveyances.
     
          (g) Taxes.  The issuance of shares of Common Stock of the
              -----                                                            
     Corporation on conversion of shares of any series of Designated Preferred
     Stock shall be without charge to the converting holder of such shares for
     any tax in respect of the issuance of such shares of Common Stock, but the
     Corporation shall not be required to pay any tax which may be payable in
     respect of any transfer involved in the issuance and delivery of such
     shares of Common Stock in any name other than that of the holder of record
     on the books of the Corporation of such shares of such series of Designated
     Preferred Stock converted, and the Corporation shall not be required to
     issue or deliver any certificate for shares of Common Stock unless and
     until the person requesting issuance thereof shall have paid to the
     Corporation the amount of such tax or shall have established to the
     satisfaction of the Corporation that such tax has been paid.
     
          (h) Reservation of Stock Issuable Upon Conversion.  Shares of Common
              ---------------------------------------------                   
     Stock issued on conversion of shares of any series of Designated Preferred
     Stock shall be issued as fully paid shares and shall be non-assessable by
     the Corporation. The Corporation shall at all times reserve and keep
     available for the purpose of effecting the conversion of shares of each
     series of Designated Preferred Stock such number of its duly authorized
     shares of Common Stock as shall be sufficient to effect the conversion of
     all outstanding shares of such series of Designated Preferred Stock, and,
     to the extent necessary in order to reserve a sufficient number of such
     shares of Common Stock, the Corporation shall, subject to appropriate
     shareholder action, amend its Certificate of Incorporation to increase the
     number of duly authorized but unissued shares of its Common Stock.
     
          (i) No Reissuance of Preferred Stock.  Shares of any series of 
              --------------------------------                          
     Designated Preferred Stock converted as provided herein shall 
<PAGE>
 
                                        - 16 -
     
     
     not be reissued and the Board of Directors shall take appropriate action
     from time to time to effect reductions in the number of shares of such
     series of Designated Preferred Stock which the Corporation is authorized to
     issue.
     
          (j) Notice of Adjustment.  Upon any adjustment of the Applicable
              --------------------                                        
     Conversion Rate or the Applicable Adjustment Price with respect to any
     series of Designated Preferred Stock, then and in each such case, the
     Corporation shall give written notice thereof, by hand or registered or
     certified mail, postage and charges prepaid, or by express overnight
     delivery, or by telecopy or telex (in which cases, the original notice
     shall be sent by means reasonably intended to result in delivery of the
     original notice to the recipient thereof on the next business day)
     addressed to each holder of such series of Designated Preferred Stock
     subject to conversion under this Section 2.4 at the address of such holder
     as shown on the books of the Corporation, which notice shall state the
     Applicable Conversion Rate for such series of Designated Preferred Stock
     resulting from such adjustment, setting forth in reasonable detail the
     method upon which such calculation is based.
     
          (k) Other Notices.  In case at any time:
              -------------                       
     
          (i)   the Corporation shall declare any dividend upon its Common Stock
     payable in cash, stock or Convertible Securities or make any other
     distribution to the holders of its Common Stock;
     
          (ii)  the Corporation shall offer for subscription pro rata to the 
                                                             --- ----       
     holders of its Common Stock any additional shares of stock of any class,
     any Convertible Securities, or other rights;
     
          (iii) there shall be any capital reorganization or reclassification
      of the capital stock of the Corporation, or a consolidation or merger of
     the Corporation with or into, or a sale of all or substantially all its
     assets to, another entity or entities; or
     
          (iv)  there shall be a voluntary or involuntary dissolution, 
     liquidation or winding up of the Corporation;
     
     then, in any one or more of said cases, the Corporation shall give, by any
     of the means specified in Section 2.4(j) hereof, addressed to each holder
     of shares of any series of Designated Preferred Stock at the address of
     such holder as shown on the books of the Corporation, (a) at least 20 days'
     prior written notice of the date on 
<PAGE>
 
                                         - 17 -
     
    
     which the books of the Corporation shall close or a record shall be taken
     for such dividend, distribution or subscription rights or for determining
     rights to vote in respect of any such reorganization, reclassification,
     consolidation, merger, sale, dissolution, liquidation or winding up and (b)
     in the case of any such reorganization, reclassification, consolidation,
     merger, sale, dissolution, liquidation or winding up, at least 20 days'
     prior written notice of the date when the same shall take place. Such
     notice in accordance with the foregoing clause (a) shall also specify, in
     the case of any such dividend, distribution or subscription rights, the
     date on which the holders of Common Stock shall be entitled thereto and
     such notice in accordance with the foregoing clause (b) shall also specify
     the date on which the holders of Common Stock shall be entitled to exchange
     their Common Stock for securities or other property deliverable upon such
     reorganization, reclassification, consolidation, merger, sale, dissolution,
     liquidation or winding up, as the case may be.
     
          3.  ADDITIONAL SERIES OF PREFERRED STOCK.  The Board of Directors is
              -------------------------------------                           
     hereby expressly authorized to provide for, designate and issue, out of the
     authorized but unissued shares of Preferred Stock, one or more other series
     of Preferred Stock in addition to the Series A Preferred Stock, Series B
     Preferred Stock, Series C Preferred Stock and Series D Preferred Stock,
     subject to the terms and conditions set forth herein. Before any shares of
     any such series are issued, the Board of Directors shall fix, and hereby is
     expressly empowered to fix, by resolution or resolutions, the following
     provisions of the shares of any such series:
     
              (a)  the designation of such series, the number of shares to 
     constitute such series and the stated value thereof, if different from the
     par value thereof;
     
              (b)  whether the shares of such series shall have voting rights 
     or powers, in addition to any voting rights required by law, and, if so,
     the terms of such voting rights or powers, which may be full or limited;
     
              (c)  the dividends, if any, payable on such series, whether any
     such dividends shall be cumulative, and, if so, from what dates, the
     conditions and dates upon which such dividends shall be payable, the
     preference or relation which such dividends shall bear to the dividends
     payable on any shares of stock of any other class or series;
<PAGE>
 
                                        - 18 -
     
     
              (d)  whether the shares of such class or series shall be subject
     to redemption by the Corporation, and, if so, the times, prices and other
     conditions of such redemption;
     
              (e)  the amount or amounts payable with respect to shares of such
     class or series upon, and the rights of the holders of such class or series
     in, the voluntary or involuntary liquidation, dissolution or winding up, or
     upon any distribution of the assets, of the Corporation;
     
              (f)  whether the shares of such class or series shall be subject
     to the operation of a retirement or sinking fund and, if so, the extent to
     and manner in which any such retirement or sinking fund shall be applied to
     the purchase or redemption of the shares of such class or series for
     retirement or other corporate purposes and the terms and provisions
     relative to the operation thereof;
     
              (g)  whether the shares of such class or series shall be 
     convertible into, or exchangeable for, shares of stock of any other class
     or series of any other securities and, if so, the price or prices or the
     rate or rates of conversion or exchange and the method, if any, of
     adjusting the same, and any other terms and conditions of conversion or
     exchange;
     
              (h)  the limitations and restrictions, if any, to be effective 
     while any shares of such class or series are outstanding upon the payment
     of dividends or the making of other distributions on, and upon the
     purchase, redemption or other acquisition by the Corporation of, the Common
     Stock or shares of stock of any other class or series;
     
              (i)  the conditions or restrictions, if any, to be effective 
     while any shares of such class or series are outstanding upon the creation
     of indebtedness of the Corporation or upon the issue of any additional
     stock, including additional shares of such class or series or of any other
     class or series; and
     
              (j)  any other powers, designations, preferences and relative,
     participating, optional or other special rights, and any qualifications,
     limitations or restrictions thereof.
     
               The powers, designations, preferences and relative, 
     participating, optional or other special rights of each series of
<PAGE>
 
                                        - 19 -
     
     
     Preferred Stock, and the qualifications, limitations or restrictions
     thereof, if any, may differ from those of any and all other series at any
     time outstanding. The Board of Directors is hereby expressly authorized
     from time to time to increase (but not above the total number of authorized
     shares of Preferred Stock) or decrease (but not below the number of shares
     thereof then outstanding) the number of shares of stock of any series of
     Preferred Stock designated to any one or more series of Preferred Stock
     pursuant to this Section 3. Different series of Preferred Stock shall not
     be construed to constitute different classes of stock for purposes of
     voting by classes unless expressly so provided in the resolution or
     resolutions adopted by the Board of Directors creating or establishing any
     such series of Preferred Stock.
     
          4.    COMMON STOCK
                ------------
     
          4.1.  Increase or Decrease in Authorized Number.  The number of
                ------------------------------------------             
     authorized shares of Common Stock may be increased or decreased (but not
     below the combined number of shares thereof then outstanding and those
     reserved for issuance upon conversion of the outstanding shares of all
     series of Designated Preferred Stock) by the affirmative vote of the
     holders of the majority of the stock of the Corporation entitled to vote,
     irrespective of the provisions of Section 242(b)(2) of the Delaware General
     Corporation Law.
     
          4.2.  Voting Rights.  Except as otherwise required by law, each holder
                -------------                                                   
     of Common Stock shall have one vote in respect of each share of Common
     Stock held of record on all matters submitted to a vote of stockholders of
     the Corporation. Except as otherwise required by law, and subject to the
     voting rights provided to the holders of any series of Preferred Stock
     (other than Series A Preferred Stock, Series B Preferred Stock, Series C
     Preferred Stock and Series D Preferred Stock), the holders of Common Stock
     and the holders of shares of Series A Preferred Stock, Series B Preferred
     Stock, Series C Preferred Stock and/or Series D Preferred Stock shall vote
     together as a single class on all matters submitted to the shareholders for
     a vote.
     
          4.3.  Dividends.  Each share of Common Stock issued and outstanding
                ---------                                                    
     shall be identical in all respects with each other such share, and no
     dividends shall be paid on any shares of Common Stock unless the same
     dividend is paid on all shares of Common Stock outstanding at the time of
     such payment. Except for and subject to those rights expressly granted to
     the holders of Preferred
<PAGE>
 
                                    - 20 -


     Stock and except as may be provided by the laws of the State of Delaware,
     the holders of Common Stock shall have all other rights of stockholders,
     including, without limitation, (a) the right to receive dividends, when and
     as declared by the Board of Directors, out of assets lawfully available
     therefor, and (b) in the event of any distribution of assets upon a
     liquidation or otherwise, the right to receive ratably and equally all the
     assets and funds of the Corporation remaining after the payment to the
     holders of the Preferred Stock or of any other class or series of stock
     ranking senior to the Common Stock upon liquidation of the specific
     preferential amounts which they are entitled to receive upon such
     liquidation.
     
          5.  REVERSE STOCK SPLIT.  Immediately upon the filing with the
              -------------------                                       
     Secretary of State of Delaware of the Certificate of Amendment that, among
     other things, amends Article FOURTH of the Corporation's Restated
     Certificate of Incorporation for purposes of including the provisions of
     this Section 5 in said Article FOURTH (the "Effective Time"), a one-for-
     seven reverse stock split of the Common Stock (the "Reverse Stock Split")
     shall become effective such that each share of Common Stock that is issued
     and outstanding or held in treasury immediately prior to the Effective Time
     shall be automatically combined and changed (without any further act) into
     one-seventh (1/7) of one share of fully paid and nonassessable Common Stock
     of the Corporation, all without changing the par value per share of the
     Common Stock. No fractional share of Common Stock shall be issued to any
     holder of record of shares of Common Stock as a result of the Reverse Stock
     Split, but in lieu of any fraction of a share which would otherwise be
     issuable to any such holder of record, there shall be paid by the
     Corporation an amount of cash equal to the pro rata value of such
     fractional share. Each stock certificate of the Corporation that represents
     shares of Common Stock and that is outstanding at any time prior to the
     Effective Time shall immediately after the Effective Time represent one-
     seventh (1/7) of the number of shares of Common Stock shown on the face of
     such stock certificate, excluding fractional shares which are subject to
     cash settlement as provided above. Within a reasonable time after the
     Effective Time, notice shall be given to the shareholders of record of the
     Common Stock instructing them to surrender their stock certificates
     representing shares of Common Stock issued prior to the Effective Time to
     the Corporation for cancellation and reissuance of new certificates
     representing the number of shares of Common Stock to which such
     shareholders are entitled after adjustment for the Reverse Stock Split. The
     aggregate amount of capital represented by the
<PAGE>
 
                                         - 21 -
     
    
     aggregate number of shares of Common Stock outstanding immediately prior to
     the Effective Time shall be appropriately adjusted to reflect the change in
     the aggregate number of shares of Common Stock outstanding immediately
     after the Effective Time without changing the par value per share of the
     Common Stock.
     
          FIFTH.  The following provisions are inserted for the management of
     the business and for the conduct of the affairs of the Corporation and for
     defining and regulating the powers of the Corporation and its directors and
     stockholders and are in furtherance and not in limitation of the powers
     conferred upon the Corporation by statute:
    
          (a) Effective as of the closing (or the first closing) of the 
     Corporation's registered initial public offering of Common Stock (the "IPO
     Closing"), the Board of Directors shall be divided into three classes of
     directors, such classes to be as nearly equal in number of directors as
     possible, having staggered three-year terms of office, the term of office
     of the directors of the first such class ("Class I") to expire as of the
     first annual meeting of the Corporation's stockholders following the IPO
     Closing, those of the second class ("Class II") to expire as of the second
     annual meeting of the Corporation's stockholders following the IPO Closing,
     and those of the third class ("Class III") as of the third annual meeting
     of the Corporation's stockholders following the IPO Closing, such that at
     each annual meeting of stockholders after the IPO Closing, nominees will
     stand for election for three-year terms to succeed those directors whose
     terms are to expire as of such meeting. At each annual meeting of
     stockholders held from and after the IPO Closing, those directors elected
     at such meeting to succeed those directors whose terms expire at such
     meeting, shall serve for a term expiring as of the third annual meeting of
     stockholders after their elections. Notwithstanding anything expressed or
     implied to the contrary in the foregoing provisions of this Article FIFTH,
     each director shall continue to serve as such until the expiration of his
     term as set forth above in this paragragph (a) and his successor is duly
     elected and qualified or until his or her earlier death, incapacity,
     resignation or removal. Subject to the right, if any, of holders of any
     series of Preferred Stock to remove any director elected by the holders of
     such series and/or any other series of Preferred Stock, any director
     serving as such pursuant to this paragraph (a) of Article FIFTH may be
     removed only for cause and only by the vote of the holders of a majority of
     the shares of the Corporation's stock entitled to vote for the election of
     directors. 
<PAGE>
 
                                    - 22 -
         
     Those directors in office immediately prior to the IPO Closing shall be
     allocated among Class I, Class II and Class III as determined by a
     resolution or resolutions of the Board of Directors, which may have been
     adopted prior to the effectiveness of this Restated Certificate of
     Incorporation.
     
          (b) The Board of Directors shall have the power and authority:  (1) 
     to adopt, amend or repeal any or all of the By-Laws of the Corporation,
     subject only to such limitations, if any, as may be from time to time
     imposed by other provisions of this Restated Certificate of Incorporation,
     by law, or by the By-Laws; and (2) to the full extent permitted or not
     prohibited by law, and without the consent of or other action by the
     stockholders, to authorize or create mortgage, pledges or other liens or
     encumbrances upon any or all of the assets, real, personal or mixed, and
     franchises of the Corporation, including after-acquired property, and to
     exercise all of the powers of the Corporation in connection therewith. 
     
          (c) Effective from and after the IPO Closing, any vacancies or new
     directorships in the Board of Directors, including unfilled vacancies or
     new directorships resulting from the removal of directors with cause or
     form any increase in the number of directors, may be filled only by the
     vote of a majority of the remaining directors then in office, although less
     than a quorum or by the sole remaining director; provided, however, that
     the foregoing provisions set forth in this paragraph (c) shall be subject
     to any contrary provisions of the Delaware General Corporation Law and/or
     the rights of the holders of any series of Preferred Stock with respect to
     the filling of vacancies or new directorships in the Board of Directors.
     
          (d) Directors need not be stockholders of the Corporation.

          SIXTH.  No director of the Corporation shall be personally liable to
     the Corporation or to any of its stockholders for monetary damages for
     breach of fiduciary duty as a director, notwithstanding any provision of
     law imposing such liability; provided, however, that, to the extent
                                  --------  -------                     
     required from time to time by applicable law, this Article SIXTH shall not
     eliminate or limit the liability of a director, to the extent such
     liability is provided by applicable law, (i) for any breach of the
     director's duty of loyalty to the Corporation or its stockholders, (ii) for
     acts or omissions not in good faith or which involve intentional misconduct
     or a knowing violation of law, (iii) under Section 174 of Title 8 of the
     Delaware Code, or (iv) for any transactions from which the director derived
     an improper personal benefit. No amendment to or repeal of this Article
     SIXTH shall apply to or have any effect on the liability or alleged
     liability of any director for or with respect to any acts or omissions of
     such director occurring prior to the effective date of such amendment or
     repeal.
     
          SEVENTH.  Each person who was or is made a party or is threatened to
     be made a party to or is otherwise involved in any action, suit or
     proceeding, by reason of being or having been a
<PAGE>
 
                                    - 23 -


     director or officer of the Corporation or serving or having served at the
     request of the Corporation as a director, trustee, officer, employee or
     agent of another corporation or of a partnership, joint venture, trust or
     other enterprise, including service with respect to an employee benefit
     plan, whether the basis of such proceeding is alleged action or failure to
     act in an official capacity as a director, trustee, officer, employee or
     agent or in any other capacity while serving as a director, trustee,
     officer, employee or agent, shall be indemnified and held harmless by the
     Corporation to the fullest extent authorized by the Delaware General
     Corporation Law, as the same exists or may hereafter be amended, against
     all expense, liability and loss (including attorneys' fees, judgments,
     fines, ERISA excise taxes or penalties and amounts paid in settlement)
     reasonably incurred or suffered by such person in connection therewith, as
     further provided in the By-Laws.
     
          EIGHTH.  Whenever a compromise or arrangement is proposed between the
     Corporation and its creditors or any class of them and/or between the
     Corporation and its stockholders or any class or series of them, any court
     of equitable jurisdiction within the State of Delaware may, on the
     application in a summary way of the Corporation or of any creditor or
     stockholder thereof or on the application of any receiver or receivers
     appointed for the Corporation under the provisions of (S)391 of Title 8 of
     the Delaware Code or on the application of trustees in dissolution or of
     any receiver or receivers appointed for the Corporation under the
     provisions of (S)279 of Title 8 of the Delaware Code, order a meeting of
     the creditors or class of creditors, and/or of the stockholders or class or
     series of stockholders of the Corporation, as the case may be, to be
     summoned in such a manner as the said court directs. If a majority of the
     number representing three-fourths (3/4ths) in value of the creditors or
     class of creditors, and/or of the stockholders or class or series of
     stockholders of the Corporation, as the case may be, agree to any
     compromise or arrangement and to any reorganization of the Corporation as a
     consequence of such compromise or arrangement, the compromise or
     arrangement and the said reorganization shall, if sanctioned by the court
     to which the said application has been made, be binding on all creditors or
     class of creditors, and/or stockholders or class or series of stockholders
     of the Corporation, as the case may be, and also on the Corporation.
     
          NINTH.  The Board of Directors, when considering a tender offer or
     merger or acquisition proposal, may take into account factors in addition
     to potential short-term economic benefits
      
<PAGE>
 
                                         - 24 -
    
     
     to stockholders of the Corporation, including without limitation (A)
     comparison of the proposed consideration to be received by stockholders in
     relation to the then current market price of the Corporation's capital
     stock, the estimated current value of the Corporation in a freely
     negotiated transaction, and the estimated future value of the Corporation
     as an independent entity and (B) the impact of such a transaction on the
     employees, suppliers, and customers of the Corporation and its effect on
     the communities in which the Corporation operates.
     
          TENTH.  Effective from and after the IPO Closing:  (i) any action 
     required or permitted to be taken by the stockholders of the Corporation
     may be taken only at a duly called annual or special meeting of the
     stockholders, and not by written consent in lieu of such a meeting; and
     (ii) subject to the right, if any, of the holders of any series of
     Preferred Stock to call special meetings of stockholders of the
     Corporation, special meetings of stockholders of the Corporation may be
     called only by the Chairman of the Board of Directors, the President, or a
     majority of the total number of directors which the Corporaton would have
     if there were no vacancies.
     
          ELEVENTH.  Effective from and after the IPO Closing, the affirmative
     vote of the holders of at least seventy-five percent (75%) of the
     outstanding voting stock of the Corporation (in addition to any separate
     class vote that may in the future be required pursuant to the terms of any
     outstanding Preferred Stock) shall be required (i) to amend or repeal the
     provisions of Articles FOURTH (to the extent such provisions relate to the
     authority of the Board of Directors to issue shares of Preferred Stock in
     one or more series, the terms of which may be determined by the Board of
     Directors), FIFTH, SEVENTH, NINTH, TENTH or ELEVENTH of the Corporation's
     Restated Certificate of Incorporation, as amended from time to time, (ii)
     to amend, adopt or repeal the Corporation's By-Laws (provided, however,
                                                          --------  ------- 
     that the provisions of this Article ELEVENTH shall in no way limit the
     power or authority of the Board of Directors to amend, adopt or repeal By-
     Laws), or (iii) to reduce the number of authorized shares of Common Stock
     or Preferred Stock."
     
     SECOND.   The amendments to the Corporation's Restated Certificate of
Incorporation were duly adopted in accordance with the provisions of Section 242
of the General Corporation Law of the State of Delaware.
<PAGE>
 
                                   - 25 -


     IN WITNESS WHEREOF, the Corporation has caused this Certificate of
Amendment to be signed by its President and attested by its Secretary this _____
day of ____, 1996.
 
                              CUBIST PHARMACEUTICALS, INC.



                              By_____________________________
                                Scott M. Rocklage,
                                President

ATTEST:



__________________________
Justin P. Morreale,
Secretary

      

<PAGE>
 
                                                                     EXHIBIT 3.3


                     RESTATED CERTIFICATE OF INCORPORATION
                                       OF
                          CUBIST PHARMACEUTICALS, INC.


       CUBIST PHARMACEUTICALS, INC., a corporation organized and existing under
and by virtue of the General Corporation Law of the State of Delaware (the
"Corporation"), hereby certifies that (i) the original Certificate of
Incorporation of the Corporation was filed by the Corporation with the Secretary
of State of Delaware on May 1, 1992, (ii) this Restated Certificate of
Incorporation was duly adopted in accordance with the provisions of Sections 242
and 245 of the Delaware General Corporation Law, and (iii) the Restated
Certificate of Incorporation restates, integrates and further amends the
Corporation's current Restated Certificate of Incorporation, as heretofore
amended, to read in its entirety as follows:

       FIRST.     The name of the Corporation is CUBIST PHARMACEUTICALS, INC.

       SECOND.    The address of the Corporation's registered office in the
State of Delaware is 1013 Centre Road, in the City of Wilmington, County of New
Castle.  The name of the Corporation's registered agent at such address is
Corporation Service Company.

       THIRD.     The purpose of the Corporation is to engage in any lawful act
or activity for which corporations may be organized under the General
Corporation Law of the State of Delaware.

       FOURTH.    The total number of shares of all classes of stock that the
Corporation shall have authority to issue is 30,000,000, consisting solely of:

     25,000,000 shares of common stock, $.001 par value per share ("Common
                Stock"); and

     5,000,000  shares of preferred stock, $.001 par value per share ("Preferred
                Stock").

     The following is a statement of the powers, designations, preferences,
privileges, and relative, participating, optional, and other special rights of
the Preferred Stock and Common Stock, respectively:

     1.   PREFERRED STOCK.  The Board of Directors is hereby expressly
          ----------------                                            
authorized to provide for, designate and issue, out of the authorized but
unissued shares of Preferred Stock, one or more other series of Preferred Stock,
subject to the terms and conditions set forth herein.  Before any shares of any
<PAGE>
 
                                      -2-

such series are issued, the Board of Directors shall fix, and hereby is
expressly empowered to fix, by resolution or resolutions, the following
provisions of the shares of any such series:

          (a)  the designation of such series, the number of shares to
constitute such series and the stated value thereof, if different from the par
value thereof;

          (b)  whether the shares of such series shall have voting rights or
powers, in addition to any voting rights required by law, and, if so, the terms
of such voting rights or powers, which may be full or limited;

          (c)  the dividends, if any, payable on such series, whether any such
dividends shall be cumulative, and, if so, from what dates, the conditions and
dates upon which such dividends shall be payable, the preference or relation
which such dividends shall bear to the dividends payable on any shares of stock
of any other class or series;

          (d)  whether the shares of such class or series shall be subject to
redemption by the Corporation, and, if so, the times, prices and other
conditions of such redemption;

          (e)  the amount or amounts payable with respect to shares of such
class or series upon, and the rights of the holders of such class or series in,
the voluntary or involuntary liquidation, dissolution or winding up, or upon any
distribution of the assets, of the Corporation;

          (f)  whether the shares of such class or series shall be subject to
the operation of a retirement or sinking fund and, if so, the extent to and
manner in which any such retirement or sinking fund shall be applied to the
purchase or redemption of the shares of such class or series for retirement or
other corporate purposes and the terms and provisions relative to the operation
thereof;

          (g)  whether the shares of such class or series shall be convertible
into, or exchangeable for, shares of stock of any other class or series of any
other securities and, if so, the price or prices or the rate or rates of
conversion or exchange and the method, if any, of adjusting the same, and any
other terms and conditions of conversion or exchange;

          (h)  the limitations and restrictions, if any, to be effective while
any shares of such class or series are outstanding upon the payment of dividends
or the making of other distributions on, and upon the purchase, redemption or
other acquisition by the Corporation of, the Common Stock or shares of stock of
any other class or series;
<PAGE>
 
                                      -3-

          (i)  the conditions or restrictions, if any, to be effective while any
shares of such class or series are outstanding upon the creation of indebtedness
of the Corporation or upon the issue of any additional stock, including
additional shares of such class or series or of any other class or series; and

          (j)  any other powers, designations, preferences and relative,
participating, optional or other special rights, and any qualifications,
limitations or restrictions thereof.

          The powers, designations, preferences and relative, participating,
optional or other special rights of each series of Preferred Stock, and the
qualifications, limitations or restrictions thereof, if any, may differ from
those of any and all other series at any time outstanding.  The Board of
Directors is hereby expressly authorized from time to time to increase (but not
above the total number of authorized shares of Preferred Stock) or decrease (but
not below the number of shares thereof then outstanding) the number of shares of
stock of any series of Preferred Stock designated to any one or more series of
Preferred Stock pursuant to this Section 1.  Different series of Preferred Stock
shall not be construed to constitute different classes of stock for purposes of
voting by classes unless expressly so provided in the resolution or resolutions
adopted by the Board of Directors creating or establishing any such series of
Preferred Stock.  No resolution, vote, or consent of the holders of the capital
stock of the Corporation shall be required in connection with the creation or
issuance of any shares of any series of Preferred Stock authorized by and
complying with the conditions of this Restated Certificate of Incorporation, the
right to any such resolution, vote, or consent being expressly waived by all
present and future holders of the capital stock of the Corporation.

     At such time as no shares of any series of Preferred Stock that may be
issued from time to time remain issued and outstanding, including without
limitation because all of such shares have been converted into shares of Common
Stock in accordance with this Restated Certificate of Incorporation, all
authorized shares of such series of Preferred Stock, automatically and without
further actions, shall be reclassified as authorized but unissued shares of
undesignated Preferred Stock of no particular class or series, and any and all
of such shares may thereafter be issued by the Board of Directors of the Company
in one or more series, and the terms of any such series may be determined by the
Board of Directors, as provided in this Section 1.
<PAGE>
 
                                      -4-

     2.   COMMON STOCK
          ------------

     2.1. Increase or Decrease in Authorized Number.  The number of authorized
          --------------------------------------------                        
shares of Common Stock may be increased or decreased (but not below the combined
number of shares thereof then outstanding by the affirmative vote of the holders
of the majority of the stock of the Corporation entitled to vote, irrespective
of the provisions of Section 242(b)(2) of the Delaware General Corporation Law.

     2.2. Voting Rights.  Except as otherwise required by law, and subject to
          -------------                                                      
the voting rights provided to the holders of any series of Preferred Stock, the
holders of Common Stock shall have full voting rights and powers to vote on all
matters submitted to stockholders of the Corporation for vote, consent or
approval, and each holder of Common Stock shall be entitled to one vote for each
share of Common Stock held of record by such holder.

     2.3. Dividend, Liquidation and Other Rights.  Each share of Common Stock
          --------------------------------------                             
issued and outstanding shall be identical in all respects with each other such
share, and no dividends shall be paid on any shares of Common Stock unless the
same dividend is paid on all shares of Common Stock outstanding at the time of
such payment.  Except for and subject to those rights expressly granted to the
holders of Preferred Stock and except as may be provided by the laws of the
State of Delaware, the holders of Common Stock shall have all other rights of
stockholders, including, without limitation, (a) the right to receive dividends,
when and as declared by the Board of Directors, out of assets lawfully available
therefor, and (b) in the event of any distribution of assets upon a liquidation
or otherwise, the right to receive ratably and equally all the assets and funds
of the Corporation remaining after the payment to the holders of the Preferred
Stock or of any other class or series of stock ranking senior to the Common
Stock upon liquidation of the specific preferential amounts which they are
entitled to receive upon such liquidation.

     FIFTH.    The following provisions are inserted for the management of the
business and for the conduct of the affairs of the Corporation and for defining
and regulating the powers of the Corporation and its directors and stockholders
and are in furtherance and not in limitation of the powers conferred upon the
Corporation by statute:

          (a) Effective as of the closing (or the first closing) of the
     Corporation's registered initial public offering of Common Stock (the "IPO
     Closing"), the Board of Directors shall be divided into three classes of
     directors, such classes to be as nearly equal in number of directors as
     possible, having staggered three-year terms of office, the term of office
     of 
<PAGE>
 
                                      -5-

     the directors of the first such class ("Class I") to expire at the first
     annual meeting of the Corporation's stockholders following the IPO Closing,
     those of the second class ("Class II") to expire at the second annual
     meeting of the Corporation's stockholders following the IPO Closing, and
     those of the third class ("Class III") at the third annual meeting of the
     Corporation's stockholders following the IPO Closing, such that at each
     such annual meeting of stockholders, nominees will stand for election for
     three-year terms to succeed those directors whose terms are to expire as of
     such meeting.  Likewise, at each other annual meeting of stockholders held
     from and after the IPO Closing, those directors elected at such meeting to
     succeed those directors whose terms expire at such meeting, shall serve for
     a term expiring at the third annual meeting of stockholders following their
     election.  Notwithstanding anything expressed or implied to the contrary in
     the foregoing provisions of this Article FIFTH, each director shall
     continue to serve as such until the expiration of his term as set forth
     above in this paragragph (a) and his successor is duly elected and
     qualified or until his or her earlier death, incapacity, resignation or
     removal.  Subject to the right, if any, of holders of any series of
     Preferred Stock to remove any director elected by the holders of such
     series and/or any other series of Preferred Stock, any director serving as
     such pursuant to this paragraph (a) of Article FIFTH may be removed only
     for cause and only by the vote of the holders of a majority of the shares
     of the Corporation's stock entitled to vote for the election of directors.
     Those directors in office immediately prior to the IPO Closing shall be
     allocated among Class I, Class II and Class III as determined by a
     resolution or resolutions of the Board of Directors, which may have been
     adopted prior to the effectiveness of this Restated Certificate of
     Incorporation.

          (b) The Board of Directors shall have the power and authority: (1) to
     adopt, amend or repeal any or all of the By-Laws of the Corporation,
     subject only to such limitations, if any, as may be from time to time
     imposed by other provisions of this Restated Certificate of Incorporation,
     by law, or by the By-Laws; and (2) to the full extent permitted or not
     prohibited by law, and without the consent of or other action by the
     stockholders, to authorize or create mortgage, pledges or other liens or
     encumbrances upon any or all of the assets, real, personal or mixed, and
     franchises of the Corporation, including after-acquired property, and to
     exercise all of the powers of the Corporation in connection therewith.

          (c) Except as the Delaware General Corporation Law may otherwise
     require, and subject to the rights of the holders of any series of
     Preferred Stock with respect the filing of vacancies or new directorships
     in the Board of Directors, any vacancies or new directorships in the Board
     of Directors, including unfilled vacancies or new directorships resulting
     from the removal of directors with cause or form any increase in the number
     of directors, may be filled only by the vote of a majority of the remaining
     directors then in office, although less than a quorum, or by the sole
     remaining director. 

          (d) Directors need not be stockholders of the Corporation.


<PAGE>
 
                                      -6-

     SIXTH.    No director of the Corporation shall be personally liable to the
Corporation or to any of its stockholders for monetary damages for breach of
fiduciary duty as a director, notwithstanding any provision of law imposing such
liability; provided, however, that, to the extent required from time to time by
           --------  -------                                                   
applicable law, this Article SIXTH shall not eliminate or limit the liability of
a director, to the extent such liability is provided by applicable law, (i) for
any breach of the director's duty of loyalty to the Corporation or its
stockholders, (ii) for acts or omissions not in good faith or which involve
intentional misconduct or a knowing violation of law, (iii) under Section 174 of
Title 8 of the Delaware Code, or (iv) for any transactions from which the
director derived an improper personal benefit.  No amendment to or repeal of
this Article SIXTH shall apply to or have any effect on the liability or alleged
liability of any director for or with respect to any acts or omissions of such
director occurring prior to the effective date of such amendment or repeal.

     SEVENTH.  Each person who was or is made a party or is threatened to be
made a party to or is otherwise involved in any action, suit or proceeding, by
reason of being or having been a director or officer of the Corporation or
serving or having served at the request of the Corporation as a director,
trustee, officer, employee or agent of another corporation or of a partnership,
joint venture, trust or other enterprise, including service with respect to an
employee benefit plan, whether the basis of such proceeding is alleged action or
failure to act in an official capacity as a director, trustee, officer, employee
or agent or in any other capacity while serving as a director, trustee, officer,
employee or agent, shall be indemnified and held harmless by the Corporation to
the fullest extent authorized by the Delaware General Corporation Law, as the
same exists or may hereafter be amended, against all expense, liability and loss
(including attorneys' fees, judgments, fines, ERISA excise taxes or penalties
and amounts paid in settlement) reasonably incurred or suffered by such person
in connection therewith, as further provided in the By-Laws.

     EIGHTH.   Whenever a compromise or arrangement is proposed between the
Corporation and its creditors or any class of them and/or between the
Corporation and its stockholders or any class or series of them, any court of
equitable jurisdiction within the State of Delaware may, on the application in a
summary way of the Corporation or of any creditor or stockholder thereof or on
the application of any receiver or receivers appointed for the Corporation under
the provisions of (S)391 of Title 8 of the Delaware Code or on the application
of trustees in dissolution or of any receiver or receivers appointed for the
Corporation under the provisions of (S)279 of Title 8 of the Delaware Code,
order a meeting of the creditors or class of creditors, and/or of the
stockholders or class or series of stockholders of the Corporation, as the case
may be, to be summoned in such a manner as the said court directs. If a majority
of the number representing three-fourths (3/4ths) in value of the creditors or
class of creditors, 
<PAGE>
 
                                      -7-

and/or of the stockholders or class or series of stockholders of the
Corporation, as the case may be, agree to any compromise or arrangement and to
any reorganization of the Corporation as a consequence of such compromise or
arrangement, the compromise or arrangement and the said reorganization shall, if
sanctioned by the court to which the said application has been made, be binding
on all creditors or class of creditors, and/or stockholders or class or series
of stockholders of the Corporation, as the case may be, and also on the
Corporation.

     NINTH.    The Board of Directors, when considering a tender offer or merger
or acquisition proposal, may take into account factors in addition to potential
short-term economic benefits to stockholders of the Corporation, including
without limitation (A) comparison of the proposed consideration to be received
by stockholders in relation to the then current market price of the
Corporation's capital stock, the estimated current value of the Corporation in a
freely negotiated transaction, and the estimated future value of the Corporation
as an independent entity and (B) the impact of such a transaction on the
employees, suppliers, and customers of the Corporation and its effect on the
communities in which the Corporation operates.

     TENTH.    Any action required or permitted to be taken by the stockholders
of the Corporation may be taken only at a duly called annual or special meeting
of the stockholders, and not by written consent in lieu of such a meeting.
Subject to the right, if any, of the holders of any series of Preferred Stock to
call special meetings of stockholders of the Corporation, special meetings of
stockholders of the Corporation may be called only by the Chairman of the Board
of Directors, the President, or a majority of the total number of directors
which the Corporaton would have if there were no vacancies.

     ELEVENTH. The affirmative vote of the holders of at least seventy-five
percent (75%) of the outstanding voting stock of the Corporation (in addition to
any separate class vote that may in the future be required pursuant to the terms
of any outstanding Preferred Stock) shall be required (i) to amend or repeal the
provisions of Articles FOURTH (to the extent such provisions relate to the
authority of the Board of Directors to issue shares of Preferred Stock in one or
more series, the terms of which may be determined by the Board of Directors),
FIFTH, SEVENTH, NINTH, TENTH or ELEVENTH of the Corporation's Restated
Certificate of Incorporation, as amended from time to time, (ii) to amend, adopt
or repeal the Corporation's By-Laws (provided, however, that the provisions of
                                     -------- --------                        
this Article ELEVENTH shall in no way limit the power or authority of the Board
of Directors to amend, adopt or repeal By-Laws), or (iii) to reduce the number
of authorized shares of Common Stock or Preferred Stock.
<PAGE>
 
                                      -8-

     IN WITNESS WHEREOF, the Corporation has caused this Restated Certificate of
Incorporation to be signed by its President and attested by its Secretary this
_____ day of ________, 1996.

                              CUBIST PHARMACEUTICALS, INC.



                              By__________________________
                                Scott M. Rocklage,
                                President

ATTEST:



__________________________
Justin P. Morreale,
Secretary

<PAGE>
 
                                                                     EXHIBIT 3.4


                             AMENDED AND RESTATED
                             --------------------
                                  BY-LAWS OF
                                  ----------
                         CUBIST PHARMACEUTICALS, INC.
                         ----------------------------

                               TABLE OF CONTENTS
                               -----------------

<TABLE>
<S>          <C>                                                          <C> 
Article I. - General......................................................1
       1.1.  Offices......................................................1
       1.2.  Seal.........................................................1
       1.3.  Fiscal Year..................................................1
Article II.- Stockholders.................................................1
       2.1.  Place of Meetings............................................1
       2.2.  Annual Meeting...............................................1
       2.3.  Special Meeting..............................................1
       2.4.  Notice of Meeting............................................2
       2.5.  Notice of Stockholder Business and Nominations...............2
       2.6.  Quorum and Adjournment.......................................4
       2.7.  Right to Vote; Proxies.......................................5
       2.8.  Voting.......................................................5
       2.9.  Inspectors...................................................5
       2.10.  Stockholders' List..........................................6
       2.11.  No Stockholder Action by Written Consent....................6
Article III.- Directors...................................................6
       3.1.  General Powers...............................................6
       3.2.  Qualifications of Directors..................................6
       3.3.  Number of Directors; Vacancies...............................6
       3.4.  Resignation..................................................7
       3.5.  Removal......................................................7
       3.6.  Place of Meetings and Books..................................8
       3.7.  Executive Committee..........................................8
       3.8.  Other Committees.............................................8
       3.9.  Powers Denied to Committees..................................8
       3.10.  Substitute Committee Member.................................9
       3.11.  Compensation of Directors...................................9
       3.12.  Regular Meetings............................................9
       3.13.  Special Meetings............................................9
       3.14.  Quorum......................................................10
       3.15.  Telephonic Participation in Meetings........................10
       3.16.  Action by Consent...........................................10
Article IV. - Officers....................................................10  
       4.1.  Selection; Statutory Officers................................10
</TABLE> 
<PAGE>
 
                                     -ii-

<TABLE> 
<S>          <C>                                                          <C> 
       4.2.  Time of Election.............................................11
       4.3.  Additional Officers..........................................11
       4.4.  Terms of Office..............................................11
       4.5.  Compensation of Officers.....................................11
       4.6.  Chairman of the Board........................................11
       4.7.  President....................................................11
       4.8.  Vice-Presidents..............................................12
       4.9.  Treasurer....................................................12
       4.10.  Secretary...................................................12
       4.11.  Assistant Secretary.........................................13
       4.12.  Assistant Treasurer.........................................13
       4.13.  Subordinate Officers........................................13
       4.14.  Removal.....................................................13
       4.15.  Vacancies...................................................13
Article V. - Stock........................................................14  
       5.1.  Stock........................................................14
       5.2.  Fractional Share Interests...................................14
       5.3.  Transfers of Stock...........................................15
       5.4.  Record Date..................................................15
       5.5.  Transfer Agent and Registrar.................................16
       5.6.  Dividends....................................................16
       5.7.  Lost, Stolen or Destroyed Certificates.......................16
Article VI. - Miscellaneous Management Provisions.........................16  
       6.1.  Checks, Drafts and Notes.....................................16
       6.2.  Notices......................................................16
       6.3.  Conflict of Interest.........................................17
       6.4.  Voting of Securities owned by this Corporation...............17
       6.5.  Inspection of Books..........................................18
Article VII. - Indemnification............................................18
       7.1.  Right to Indemnification.....................................18
       7.2.  Right of Indemnitee to Bring Suit............................19
       7.3.  Non-Exclusivity of Rights....................................20
       7.4.  Insurance....................................................20
       7.5.  Indemnification of Employees and Agents of the Corporation...20
Article VIII. - Amendments................................................21
       8.1.  Amendments...................................................21
</TABLE>
<PAGE>
 
                             AMENDED AND RESTATED
                             --------------------
                                  BY-LAWS OF
                                  ----------
                         CUBIST PHARMACEUTICALS, INC.
                         ----------------------------

                             ARTICLE I. - GENERAL.
                             -------------------- 

     1.1.  OFFICES.  The registered office shall be in the City of Wilmington,
           -------
County of New Castle, State of Delaware. The Corporation may also have offices
at such other places both within and without the State of Delaware as the Board
of Directors may from time to time determine or the business of the Corporation
may require.

     1.2.  SEAL.  The seal of the Corporation shall be in the form of a circle
           ----
and shall have inscribed thereon the name of the Corporation, the year of its
organization and the words "Corporate Seal, Delaware".

     1.3.  FISCAL YEAR.  The fiscal year of the Corporation shall be the period
           -----------
from January 1 though December 31.

                          ARTICLE II. - STOCKHOLDERS.
                          -------------------------- 

     2.1.  PLACE OF MEETINGS.  All meetings of the stockholders shall be held at
           -----------------
the office of the Corporation in Cambridge, Massachusetts except such meetings
as the Board of Directors expressly determine shall be held elsewhere, in which
case meetings may be held upon notice as hereinafter provided at such other
place or places within or without the Commonwealth of Massachusetts as the Board
of Directors shall have determined and as shall be stated in such notice.

     2.2.  ANNUAL MEETING.  The annual meeting of stockholders of the
           --------------  
Corporation shall be held on such date and at such place and time as may be
fixed by resolution of the Board of Directors and stated in the notice of the
meeting. At each annual meeting of stockholders, the stockholders entitled to
vote shall elect such members of the Board of Directors as are standing for
election at such meeting, and shall transact such other business as may properly
be brought before the meeting. At the annual meeting any business may be
transacted, irrespective of whether the notice calling such meeting shall have
contained a reference thereto, except where notice is required by law, the
Corporation's Restated Certificate of Incorporation, as amended and in effect
from time to time (the "Restated Certificate of Incorporation"), or these By-
Laws.

     2.3.  SPECIAL MEETING.  Subject to the rights of the holders of any series
           ---------------
of preferred stock of the Corporation ("Preferred Stock") with
<PAGE>
 
                                      -2-

respect to calling special meetings of stockholders of the Corporation, special
meetings of the stockholders for any purpose or purposes may only be called by
the Chairman of the Board of Directors, the President, or a majority of the
total number of directors which the Corporation would have if there were no
vacancies (the "Whole Board"). Only such business shall be conducted at a
special meeting as shall have been brought before the meeting pursuant to the
Corporation's notice of meeting.

     2.4.  NOTICE OF MEETING.  Written notice of any meeting of the stockholders
           -----------------      
stating the place, date and hour of the meeting shall be given to each
stockholder entitled to vote at such meeting not less than ten nor more than
sixty days before the date of the meeting. Notice need not be given to any
stockholder who submits a written waiver of notice signed by him before or after
the time stated therein. Attendance of a stockholder at a meeting of
stockholders shall constitute a waiver of notice of such meeting, except when
the stockholder attends the meeting for the express purpose of objecting, at the
beginning of the meeting, to the transaction of any business because the meeting
is not lawfully called or convened. Neither the business to be transacted at,
nor the purpose of, any regular or special meeting of the stockholders need be
specified in any written waiver of notice. Any previously scheduled meeting of
the stockholders may be postponed, and (unless the Restated Certificate of
Incorporation otherwise provides) any special meeting of the stockholders may be
canceled, by resolution of the Board of Directors upon public notice given prior
to the date previously scheduled for such meeting of stockholders.

     2.5.  NOTICE OF STOCKHOLDER BUSINESS AND NOMINATIONS.     
           ----------------------------------------------

               (a)  Nomination of Directors.  Only persons who are nominated in
                    ---------- -- ---------
accordance with the procedures set forth in these By-Laws shall be eligible to
serve as directors. Nominations of persons for election to the Board of
Directors of the Corporation may be made at a meeting of stockholders (a) by or
at the direction of the Board of Directors or (b) by any stockholder of the
Corporation who is a stockholder of record at the time of giving of notice for
the election of directors at the meeting and who complies with the notice
procedures set forth in this Section 2.5(a). Such nominations, other than those
made by or at the direction of the Board of Directors, shall be made pursuant to
timely notice in writing to the Secretary of the Corporation. To be timely, a
stockholder's notice shall be delivered to or mailed and received at the
principal executive offices of the Corporation not less than 50 days prior to
the meeting; provided, however, that in the event that less than 55 days' notice
             --------  -------
or prior public disclosure of the date of the meeting is given or made to
stockholders, notice by the stockholder to be timely must be so received not
later than the close of 
<PAGE>
 
                                      -3-

business on the seventh day following the day on which such notice of the date
of the meeting or such public disclosure was made. Such stockholder's notice
shall set forth (a) as to each person whom the stockholder proposes to nominate
for election or reelection as a director, all information relating to such
person that is required to be disclosed in solicitations of proxies for election
of directors, or is otherwise required, in each case pursuant to Regulation 14A
under the Securities Exchange Act of 1934, as amended (including such person's
written consent to being named in the proxy statement as a nominee and to
serving as a director if elected), and (b) as to the stockholder giving the
notice (i) the name and address, as they appear on the Corporation's books, of
such stockholder and (ii) the class and number of shares of the Corporation
which are beneficially owned by such stockholder. At the request of the Board of
Directors, any person nominated by the Board of Directors for election as a
director shall furnish to the Secretary of the Corporation that information
required to be set forth in a stockholder's notice of nomination which pertains
to the nominee. No person shall be eligible to serve as a director of the
Corporation unless nominated in accordance with the procedures set forth in this
Section 2.5(a). The chairman of the meeting shall, if the facts warrant,
determine and declare to the meeting that a nomination was not made in
accordance with the procedures prescribed by the By-Laws, and if he should so
determine, he shall so declare to the meeting and the defective nomination shall
be disregarded. Notwithstanding the foregoing provisions of this Section 2.5(a),
a stockholder shall also comply with all applicable requirements of the
Securities Exchange Act of 1934, as amended, and the rules and regulations
thereunder with respect to the matters set forth in this Section 2.5(a).

               (b)  Notice of Business.  At any meeting of the stockholders,
                    ------ -- --------
only such business shall be conducted as shall have been brought before the
meeting (a) by or at the direction of the Board of Directors or (b) by any
stockholder of the Corporation who is a stockholder of record at the time of
giving of the notice provided for in this Section 2.5(b), who shall be entitled
to vote at such meeting and who complies with the notice procedures set forth in
this Section 2.5(b). For business to be properly brought before a stockholder
meeting by a stockholder, the stockholder must have given timely notice thereof
in writing to the Secretary of the Corporation. To be timely, a stockholder's
notice must be delivered to or mailed and received at the principal executive
offices of the Corporation not less than 50 days prior to the meeting; provided,
                                                                       --------
however, that in the event that less than 55 days' notice or prior public
- -------
disclosure of the date of the meeting is given or made to stockholders, notice
by the stockholder to 
<PAGE>
 
                                      -4-

be timely must be received no later than the close of business on the seventh
day following the day on which such notice of the date of the meeting was mailed
or such public disclosure was made. A stockholder's notice to the Secretary
shall set forth as to each matter the stockholder proposes to bring before the
meeting (a) a brief description of the business desired to be brought before the
meeting and the reasons for conducting such business at the meeting; (b) the
name and address, as they appear on the Corporation's books, of the stockholder
proposing such business, (c) the class and number of shares of the Corporation
which are beneficially owned by the stockholder, and (d) any material interest
of the stockholder in such business. Notwithstanding anything in the By-Laws to
the contrary, no business shall be conducted at a stockholder meeting except (i)
in accordance with the procedures set forth in this Section 2.5(b) or (ii) with
respect to nominations of persons for election as directors of the Corporation,
in accordance with the provisions of Section 2.5(a) hereof. The Chairman of the
meeting shall, if the facts warrant, determine and declare to the meeting that
business was not properly brought before the meeting and in accordance with the
provisions of the By-Laws, and if he should so determine, he shall so declare to
the meeting and any such business not properly brought before the meeting shall
not be transacted. Notwithstanding the foregoing provisions of this Section
2.5(b), a stockholder shall also comply with all applicable requirements of the
Securities Exchange Act of 1934, as amended, and the rules and regulations
thereunder with respect to the matters set forth in this Section.

     2.6.  QUORUM AND ADJOURNMENT.  At all meetings of the stockholders, the
           ----------------------
holders of a majority of the stock issued and outstanding and entitled to vote
thereat, present in person or represented by proxy, shall constitute a quorum
requisite for the transaction of business except as otherwise provided by law,
by the Restated Certificate of Incorporation or by these By-Laws. The chairman
of the meeting or a majority of the shares so represented may, whether or not
there is such a quorum, adjourn the meeting from time to time without notice
other than announcement at the meeting. If the adjournment is for more than
thirty days, or if after the adjournment a new record date is fixed for the
adjourned meeting, a notice of the adjourned meeting shall be given to each
stockholder of record entitled to vote at the meeting. At such adjourned
meeting, at which the requisite amount of voting stock shall be represented, any
business may be transacted which might have been transacted if the meeting had
been held as originally called. The stockholders present at a duly called
meeting at which quorum is present may continue to transact business until
adjournment, notwithstanding the withdrawal of enough stockholders to leave less
than a quorum.
<PAGE>
 
                                   -5-     

     2.7. RIGHT TO VOTE; PROXIES.  Each holder of a share or shares of capital
          ----------------------    
stock of the Corporation having the right to vote at any meeting shall be
entitled to one vote for each such share of stock held by him. Any stockholder
entitled to vote at any meeting of stockholders may vote either in person or by
proxy, but no proxy which is dated more than three years prior to the meeting at
which it is offered shall confer the right to vote thereat unless the proxy
provides that it shall be effective for a longer period. A proxy may be granted
by a writing executed by the stockholder or his authorized officer, director,
employee or agent or by transmission or authorization of transmission of a
telegram, cablegram, or other means of electronic transmission to the person who
will be the holder of the proxy or to a proxy solicitation firm, proxy support
service organization or like agent duly authorized by the person who will be the
holder of the proxy to receive such transmission, subject to the conditions set
forth in Section 212 of the Delaware General Corporation Law, as it may be
amended from time to time (the "Delaware GCL").

     2.8.  VOTING.  At all meetings of stockholders, except as otherwise
           ------
expressly provided for by statute, the Restated Certificate of Incorporation or
these By-Laws, (i) in all matters other than the election of directors, the
affirmative vote of a majority of shares present in person or represented by
proxy at the meeting and entitled to vote on such matter shall be the act of the
stockholders and (ii) directors shall be elected by a plurality of the votes of
the shares present in person or represented by proxy at the meeting and entitled
to vote on the election of directors. Except as otherwise expressly provided by
law, the Restated Certificate of Incorporation or these By-Laws, at all meetings
of stockholders the voting shall be by ballot, each of which shall state the
name of the stockholder voting and the number of shares voted by him, and, if
such ballot be cast by a proxy, it shall also state the name of the proxy. The
chairman of the meeting shall fix and announce at the meeting the date and time
of the opening and the closing of the polls for each matter upon which the
stockholders will vote at a meeting

     2.9.  INSPECTORS.  The Board of Directors by resolutions shall appoint one
           ----------
or more inspectors, which inspector or inspectors may include individuals who
serve the Corporation in other capacities, including, without limitation, as
officers, employees, agents or representatives, to act at the meeting of
stockholders and make a written report thereof. One or more persons may be
designated as alternate inspectors to replace any inspector who fails to act. If
no inspector or alternate has been appointed to act or is able to act at a
meeting of stockholders, the chairman of the meeting shall appoint one or more
inspectors to act at the meeting. Each inspector, before discharging his or her
duties, shall take and sign an oath 
<PAGE>
 
                                      -6-

faithfully to execute the duties of inspector with strict impartiality and
according to the best of his or her ability. The inspectors shall have the
duties prescribed by law.

     2.10.  STOCKHOLDERS' LIST.  Acomplete list of the stockholders entitled to
            ------------------
vote at any meeting of stockholders, arranged in alphabetical order and showing
the address of each stockholder, and the number of shares registered in the name
of each stockholder, shall be prepared by the Secretary and filed either at a
place within the city where the meeting is to be held, which place shall be
specified in the notice of the meeting, or, if not so specified, at the place
where the meeting is to be held, at least 10 days before such meeting, and shall
at all times during the usual hours for business, and during the whole time of
said election, be open to the examination of any stockholder for a purpose
germane to the meeting.

     2.11.  NO STOCKHOLDER ACTION BY WRITTEN CONSENT.  Unless otherwise provided
            ----------------------------------------
in the Restated Certificate of Incorporation, and subject to the rights, if any,
of the holders of Preferred Stock to take action by written consent, any action
required or permitted to be taken by the stockholders of the Corporation must be
effected at an annual or special meeting of stockholders of the Corporation and
may not be effected by any consent in writing by such stockholders.

                          ARTICLE III. - DIRECTORS.
                          ------------------------ 

     3.1.  GENERAL POWERS.  In addition to the powers and authority expressly
           --------------
conferred upon them by these By-Laws, the Board of Directors may exercise all
such powers of the Corporation and do all such lawful acts and things as are not
by statute or by the Restated Certificate of Incorporation or by these By-Laws
directed or required to be exercised or done by the stockholders.

     3.2.  QUALIFICATIONS OF DIRECTORS.  Adirector need not be a stockholder, a
           ---------------------------
citizen of the United States, or a resident of the State of Delaware.

     3.3.  NUMBER OF DIRECTORS: VACANCIES.  The number of directors constituting
           ------------------------------
the full Board of Directors shall be fixed from time to time exclusively
pursuant to a resolution adopted by a majority of the Whole Board of Directors.
Effective as of the closing (or the first closing) of the Corporation's
registered initial public offering of Common Stock (the "IPO Closing"), the
Board of Directors shall consist of three classes of directors, such classes to
be as nearly equal in number of directors as possible, having staggered three-
year terms of office, the term of office of the 
<PAGE>
 
                                      -7-

directors of the first such class to expire at the first annual meeting of the
Corporation's stockholders following the IPO Closing, those of the second class
to expire at the second annual meeting of the Corporation's stockholders
following the IPO Closing, and those of the third class at the third annual
meeting of the Corporation's stockholders following the IPO Closing, such that
at each such annual meeting of stockholders, nominees will stand for election
for three-year terms to succeed those directors whose terms are to expire at
such meeting. Likewise, at each other annual meeting of stockholders held from
and after the IPO Closing, those nominees elected at such meeting to succeed
those directors whose terms expire at such meeting, shall serve for a term
expiring at the third annual meeting of stockholders following their election.
Members of the Board of Directors shall hold office until the annual meeting of
stockholders for the year in which their term is scheduled to expire as set
forth above in this Section 3.3 and their respective successors are duly elected
and qualified or until their earlier death, incapacity, resignation, or removal.
Except as the Delaware GCL may otherwise require, and subject to the rights of
the holders of any series of Preferred Stock with respect to the filling of
vacancies or new directorships in the Board of Directors, any vacancies or new
directorships in the Board of Directors, including unfilled vacancies or new
directorships resulting from the removal of directors for cause or from any
increase in the number of directors, may be filled only by the vote of a
majority of the remaining directors then in office, although less than a quorum,
or by the sole remaining director.

     3.4.  RESIGNATION.  Any director of this Corporation may resign at any time
           -----------
by giving written notice to the Chairman of the Board, if any, the President or
the Secretary of the Corporation. Such resignation shall take effect at the time
specified therein, at the time of receipt if no time is specified therein or at
the time of acceptance if the effectiveness of such resignation is conditioned
upon its acceptance. Unless otherwise specified therein, the acceptance of such
resignation shall not be necessary to make it effective.

     3.5.  REMOVAL.  Subject to the rights of the holders of any series of
           -------
Preferred Stock with respect the removal of any director elected by the holders
of such series and/or any other series of Preferred Stock, any director or the
entire Board of Directors may be removed from office at any time, but only for
cause and only by the affirmative vote of the holders of a majority of the then-
outstanding shares entitled to vote thereon, voting together as a class.

     3.6.  PLACE OF MEETINGS AND BOOKS.  The Board of Directors may hold their
           ---------------------------
meetings and keep the books of the Corporation outside the 
<PAGE>
 
                                      -8-

State of Delaware, at such places as they may from time to time determine.

     3.7.  EXECUTIVE COMMITTEE.  There may be an executive committee of one or
           -------------------
more directors designated by resolution passed by a majority of the Whole Board.
The act of a majority of the members of such committee shall be the act of the
committee. Said committee may meet at stated times or on notice to all by any of
their own number, and shall have and may exercise those powers of the Board of
Directors in the management of the business affairs of the Corporation as are
provided by law and may authorize the seal of the Corporation to be affixed to
all papers which may require it. Vacancies in the membership of the committee
shall be filled by the Board of Directors at a regular meeting or at a special
meeting called for that purpose.

     3.8.  OTHER COMMITTEES.  The Board of Directors may also designate one or
           ----------------
more committees in addition to the executive committee, by resolution or
resolutions passed by a majority of the Whole Board; such committee or
committees shall consist of one or more directors of the Corporation, and to the
extent provided in the resolution or resolutions designating them, shall have
and may exercise specific powers of the Board of Directors in the management of
the business and affairs of the Corporation to the extent permitted by statute
and shall have power to authorize the seal of the Corporation to be affixed to
all papers which may require it. Such committee or committees shall have such
name or names as may be determined from time to time by resolution adopted by
the Board of Directors.

     3.9.  POWERS DENIED TO COMMITTEES.  Committees of the Board of Directors
           ---------------------------
shall not, in any event, have any power or authority to amend the Restated
Certificate of Incorporation (except that a committee may, to the extent
authorized in the resolution or resolutions providing for the issuance of shares
adopted by the Board of Directors as provided in Section 151(a) of the Delaware
GCL, fix the designations and any of the preferences or rights of such shares
relating to dividends, redemption, dissolution, any distribution of assets of
the Corporation or the conversion into, or the exchange of such shares for,
shares of any other class or classes or any other series of the same or any
other class or classes of stock of the Corporation or fix the number of shares
of any series of stock or authorize the increase or decrease of the shares of
any series), adopt an agreement of merger or consolidation, recommend to the
stockholders the sale, lease or exchange of all or substantially all of the
Corporation's property and assets, recommend to the stockholders a dissolution
of the Corporation or a revocation of a dissolution or to amend the By-Laws of
<PAGE>
 
                                      -9-

the Corporation. Further, no committee of the Board of Directors shall have the
power or authority to declare a dividend, to authorize the issuance of stock or
to adopt a certificate of ownership and merger pursuant to Section 253 of the
Delaware GCL, unless the resolution or resolutions designating such committee
expressly so provides.

     3.10.  SUBSTITUTE COMMITTEE MEMBER.  In the absence or on the
            ---------------------------
disqualification of a member of a committee, the member or members thereof
present at any meeting and not disqualified from voting, whether or not he or
they constitute a quorum, may unanimously appoint another member of the Board of
Directors to act at the meeting in the place of such absent or disqualified
member. Any committee shall keep regular minutes of its proceedings and report
the same to the Board of Directors as may be required by the Board of Directors.

     3.11.  COMPENSATION OF DIRECTORS.  The Board of Directors shall have the
            -------------------------
power to fix the compensation of directors and members of committees of the
Board of Directors. The directors may be paid their expenses, if any, of
attendance at each meeting of the Board of Directors and may be paid a fixed sum
for attendance at each meeting of the Board of Directors and/or a stated annual
fee (some or all of which may be paid in the form of capital stock of the
Corporation) as director. No such payment shall preclude any director from
serving the Corporation in any other capacity and receiving compensation
therefor. Members of special or standing committees may be allowed like
compensation for attending committee meetings.

     3.12.  REGULAR MEETINGS.  A regular meeting of the Board of Directors shall
            ----------------
be held without other notice than this Section 3.12, immediately after, and at
the same place as, the Annual Meeting of Stockholders. The Board of Directors
may, by resolutions, provide the time and place for the holding of additional
regular meetings without other notice than such resolution. Such regular
meetings shall be held at such place within or without the State of Delaware as
shall be fixed by the Board of Directors.

     3.13.  SPECIAL MEETINGS.  Special meetings of the Board of Directors may be
            ----------------
called by the Chairman of the Board of Directors, if any, or the President, on
two (2) days notice to each director, or such shorter period of time before the
meeting as will nonetheless be sufficient for the convenient assembly of the
directors so notified; special meetings shall be called by the Secretary in like
manner and on like notice, on the written request of two or more directors.
<PAGE>
 
                                     -10-

     3.14.  QUORUM.  At all meetings of the Board of Directors, a majority of
            ------
the total number of directors shall be necessary and sufficient to constitute a
quorum for the transaction of business, and the act of a majority of the
directors present at any meeting at which there is a quorum shall be the act of
the Board of Directors, except as may be otherwise specifically permitted or
provided by statute, or by the Restated Certificate of Incorporation, or by
these By-Laws. If at any meeting of the Board of Directors there shall be less
than a quorum present, a majority of those present may adjourn the meeting from
time to time until a quorum is obtained, and no further notice thereof need be
given other than by announcement at said meeting which shall be so adjourned.

     3.15.  TELEPHONIC PARTICIPATION IN MEETINGS.  Members of the Board of
            ------------------------------------
Directors or any committee designated by such board may participate in a meeting
of the Board of Directors or committee thereof by means of conference telephone
or similar communications equipment by means of which all persons participating
in the meeting can hear each other, and participation in a meeting pursuant to
this section shall constitute presence in person at such meeting.

     3.16.  ACTION BY CONSENT.  Unless otherwise restricted by the Restated
            -----------------
Certificate of Incorporation or these By-Laws, any action required or permitted
to be taken at any meeting of the Board of Directors or of any committee thereof
may be taken without a meeting, if written consent thereto is signed by all
members of the Board of Directors or of such committee, as the case may be, and
such written consent is filed with the minutes of proceedings of the Board of
Directors or committee.

                            ARTICLE IV. - OFFICERS.
                            ---------------------- 

     4.1.  SELECTION; STATUTORY OFFICERS.  The officers of the Corporation shall
           -----------------------------
be chosen by the Board of Directors. There shall be a President, a Secretary and
a Treasurer, and there may be a Chairman of the Board of Directors, one or more
Vice Presidents, one or more Assistant Secretaries, and one or more Assistant
Treasurers, as the Board of Directors may elect. Any number of offices may be
held by the same person, unless the Restated Certificate of Incorporation or
these By-Laws otherwise provide.

     4.2.  TIME OF ELECTION.  The officers above named shall be chosen by the
           ----------------
Board of Directors at its first meeting after each annual meeting of
stockholders. None of said officers need be a director.

     4.3.  ADDITIONAL OFFICERS.  The Board of Directors may appoint such other
           -------------------
officers and agents as it shall deem necessary, who shall hold 
<PAGE>
 
                                     -11-

their offices for such terms and shall exercise such powers and perform such
duties as shall be determined from time to time by the Board of Directors.

     4.4.  TERMS OF OFFICE.  The officers of the Corporation shall hold office
           ---------------
until their successors are chosen and qualify. Any officer elected or appointed
by the stockholders may be removed at any time by the affirmative vote of a
majority of the stockholders. Any vacancy occurring in any office of the
Corporation shall be filled by the Board of Directors.

     4.5.  COMPENSATION OF OFFICERS.  The Board of Directors (or a duly
           ------------------------
appointed committee of the Board of Directors) shall have power to fix the
compensation of all officers of the Corporation.

     4.6.  CHAIRMAN OF THE BOARD.  The Chairman of the Board of Directors, if
           ---------------------
any, otherwise the President, if a director, or such other director as the Board
may choose, shall preside at all meetings of the Board of Directors and of the
stockholders of the Corporation. In the absence of the President, or in the
event of the President's inability or refusal to act, the Chairman of the Board
shall perform the duties and exercise the powers of the President until such
vacancy shall be filled in the manner prescribed by these By-Laws or by law. The
Chairman of the Board shall have such other powers and perform such other duties
as may from time to time be prescribed by the Board of Directors or these By-
Laws.

     4.7.  PRESIDENT.  Unless the Board of Directors otherwise determines, the
           ---------
President shall be the chief executive officer and head of the Corporation.
Unless there is a Chairman of the Board, the President shall preside at all
meetings of directors and stockholders. Under the supervision of the Board of
Directors and of the executive committee, the President shall have the general
control and management of its business and affairs, subject, however, to the
right of the Board of Directors and of the executive committee to confer any
specific power, except such as may be by statute exclusively conferred on the
President, upon any other officer or officers of the Corporation. The President
shall perform and do all acts and things incident to the position of President
and such other duties as may be assigned to him from time to time by the Board
of Directors or the executive committee.

     4.8.  VICE-PRESIDENTS.  The Vice-Presidents shall perform such of the
           ---------------
duties of the President on behalf of the Corporation as may be respectively
assigned to them from time to time by the Board of Directors or by the executive
committee or by the President. The Board of Directors or the executive committee
may designate one of the Vice-Presidents as 
<PAGE>
 
                                     -12-

the Executive Vice-President, and in the absence or inability of the President
to act, such Executive Vice-President shall have and possess all of the powers
and discharge all of the duties of the President, subject to the control of the
Board of Directors and of the executive committee.

     4.9.  TREASURER.  The Treasurer shall have the care and custody of all the
           ---------
funds and securities of the Corporation which may come into his hands as
Treasurer, and the power and authority to endorse checks, drafts and other
instruments for the payment of money for deposit or collection when necessary or
proper and to deposit the same to the credit of the Corporation in such bank or
banks or depository as the Board of Directors or the executive committee, or the
officers or agents to whom the Board of Directors or the executive committee may
delegate such authority, may designate, and he may endorse all commercial
documents requiring endorsements for or on behalf of the Corporation. He may
sign all receipts and vouchers for the payments made to the Corporation. He
shall render an account of his transactions to the Board of Directors or to the
executive committee as often as the Board of Directors or the committee shall
require the same. He shall enter regularly in the books to be kept by him for
that purpose full and adequate account of all moneys received and paid by him on
account of the Corporation. He shall perform all acts incident to the position
of Treasurer, subject to the control of the Board of Directors and of the
executive committee. He shall when requested, pursuant to vote of the Board of
Directors or the executive committee, give a bond to the Corporation conditioned
for the faithful performance of his duties, the expense of which bond shall be
borne by the Corporation.

     4.10.  SECRETARY.  The Secretary shall keep the minutes of all meetings of
            ---------
the Board of Directors and of the stockholders; and shall attend to the giving
and serving of all notices of the Corporation. Except as otherwise ordered by
the Board of Directors or the executive committee, the Secretary shall attest
the seal of the Corporation upon all contracts and instruments executed under
such seal and shall affix the seal of the Corporation thereto and to all
certificates of shares of capital stock of the Corporation. The Secretary shall
have charge of the stock certificate book, transfer book and stock ledger, and
such other books and papers as the Board of Directors or the executive committee
may direct. He shall, in general, perform all the duties of Secretary, subject
to the control of the Board of Directors and of the executive committee.

     4.11.  ASSISTANT SECRETARY.  The Assistant Secretary, or if there be more
            -------------------
than one, the assistant secretaries in the order determined by the Board of
Directors (or if there be no such determination, then in the order of their
election) shall, in the absence of the Secretary or in the event of 
<PAGE>
 
                                     -13-

his inability or refusal to act, perform the duties and exercise the powers of
the Secretary and shall perform such other duties and have such other powers as
the Board of Directors may from time to time prescribe.

     4.12.  ASSISTANT TREASURER.  The Assistant Treasurer, or if there shall be
            -------------------
more than one, the Assistant Treasurers in the order determined by the Board of
Directors (or if there be no such determination, then in the order of their
election), shall, in the absence of the Treasurer or in the event of his
inability or refusal to act, perform the duties and exercise the powers of the
Treasurer and shall perform such other duties and have such other powers as the
Board of Directors may from time to time prescribe.

     4.13.  SUBORDINATE OFFICERS.  The Board of Directors may select such
            --------------------
subordinate officers as it may deem desirable. Each such officer shall hold
office for such period, have such authority, and perform such duties as the
Board of Directors may prescribe. The Board of Directors may, from time to time,
authorize any officer to appoint and remove subordinate officers and to
prescribe the powers and duties thereof.

     4.14.  REMOVAL.  Any officer elected, or agent appointed, by the Board of
            -------
Directors may be removed by the affirmative vote of a majority of the Whole
Board whenever, in their judgment, the best interests of the Corporation would
be served thereby. Any officer or agent appointed by the President may be
removed by him whenever, in his judgment, the best interests of the Corporation
would be served thereby. No elected officer shall have any contractual rights
against the Corporation for compensation by virtue of such election beyond the
date of the election of his successor, his death, his resignation or his
removal, whichever event shall first occur, except as otherwise provided in an
employment contract or under an employee deferred compensation plan.

     4.15.  VACANCIES.  Anewly created elected office and a vacancy in any
            ---------
elected office because of death, resignation or removal may be filled by the
Board of Directors for the unexpired portion of the term at any meeting of the
Board of Directors. Any vacancy in an office appointed by the President because
of death, resignation, or removal may be filled by the President.


                              ARTICLE V. - STOCK.
                              ------------------ 

     5.1.  STOCK.  Each stockholder shall be entitled to a certificate or
           -----
certificates of stock of the Corporation in such form as the Board of 
<PAGE>
 
                                     -14-

Directors may from time to time prescribe. The certificates of stock of the
Corporation shall be numbered and shall be entered in the books of the
Corporation as they are issued. They shall certify the holder's name and number
and class of shares and shall be signed by both of (i) either the President or a
Vice-President, and (ii) any one of the Treasurer or an Assistant Treasurer or
the Secretary or an Assistant Secretary, and shall be sealed with the corporate
seal of the Corporation. If such certificate is countersigned (l) by a transfer
agent other than the Corporation or its employee, or, (2) by a registrar other
than the Corporation or its employee, the signature of the officers of the
Corporation and the corporate seal may be facsimiles. In case any officer or
officers who shall have signed, or whose facsimile signature or signatures shall
have been used on, any such certificate or certificates shall cease to be such
officer or officers of the Corporation, whether because of death, resignation or
otherwise, before such certificate or certificates shall have been delivered by
the Corporation, such certificate or certificates may nevertheless be adopted by
the Corporation and be issued and delivered as though the person or persons who
signed such certificate or certificates or whose facsimile signature shall have
been used thereon had not ceased to be such officer or officers of the
Corporation.

     5.2.  FRACTIONAL SHARE INTERESTS.  The Corporation may, but shall not be
           --------------------------
required to, issue fractions of a share. If the Corporation does not issue
fractions of a share, it shall (i) arrange for the disposition of fractional
interests by those entitled thereto, (ii) pay in cash the fair value of
fractions of a share as of the time when those entitled to receive such
fractions are determined, or (iii) issue scrip or warrants in registered or
bearer form which shall entitle the holder to receive a certificate for a full
share upon the surrender of such scrip or warrants aggregating a full share. A
certificate for a fractional share shall, but scrip or warrants shall not unless
otherwise provided therein, entitle the holder to exercise voting rights, to
receive dividends thereon, and to participate in any of the assets of the
Corporation in the event of liquidation. The Board of Directors may cause scrip
or warrants to be issued subject to the conditions that they shall become void
if not exchanged for certificates representing full shares before a specified
date, or subject to the conditions that the shares for which scrip or warrants
are exchangeable may be sold by the Corporation and the proceeds thereof
distributed to the holders of scrip or warrants, or subject to any other
conditions which the Board of Directors may impose.

     5.3.  TRANSFERS OF STOCK.  Subject to any transfer restrictions then in
           ------------------
force, the shares of stock of the Corporation shall be transferable only upon
its books by the holders thereof in person or by their duly authorized 
<PAGE>
 
                                     -15-

attorneys or legal representatives and upon such transfer the old certificates
shall be surrendered to the Corporation by the delivery thereof to the person in
charge of the stock and transfer books and ledgers or to such other person as
the directors may designate by whom they shall be cancelled and new certificates
shall thereupon be issued. The Corporation shall be entitled to treat the holder
of record of any share or shares of stock as the holder in fact thereof and
accordingly shall not be bound to recognize any equitable or other claim to or
interest in such share on the part of any other person whether or not it shall
have express or other notice thereof save as expressly provided by the laws of
Delaware.

     5.4.  RECORD DATE.  For the purpose of determining the stockholders
           -----------
entitled to notice of or to vote at any meeting of stockholders or any
adjournment thereof, or to express consent to corporate action in writing
without a meeting, or entitled to receive payment of any dividend or other
distribution or the allotment of any rights, or entitled to exercise any rights
in respect of any change, conversion, or exchange of stock or for the purpose of
any other lawful action, the Board of Directors may fix, in advance, a record
date, which shall not be more than sixty (60) days nor less than ten (10) days
before the date of such meeting, nor more than sixty (60) days prior to any
other action. If no such record date is fixed by the Board of Directors, the
record date for determining stockholders entitled to notice of or to vote at a
meeting of stockholders shall be at the close of business on the day next
preceding the day on which notice is given, or, if notice is waived, at the
close of business on the day next preceding the day on which the meeting is
held; the record date for determining stockholders entitled to express consent
to corporate action in writing without a meeting, when no prior action by the
Board of Directors is necessary, shall be the day on which the first written
consent is expressed; and the record date for determining stockholders for any
other purpose shall be at the close of business on the day on which the Board of
Directors adopts the resolution relating thereto. A determination of
stockholders of record entitled to notice of or to vote at any meeting of
stockholders shall apply to any adjournment of the meeting; provided, however,
that the Board of Directors may fix a new record date for the adjourned meeting.

     5.5.  TRANSFER AGENT AND REGISTRAR.  The Board of Directors may appoint one
           ----------------------------
or more transfer agents or transfer clerks and one or more registrars and may
require all certificates of stock to bear the signature or signatures of any of
them.
<PAGE>
 
                                     -16-

     5.6.  DIVIDENDS.
           --------- 

            (a)  Power to Declare.  Dividends upon the capital stock of the
                 ----------------
     Corporation, subject to the provisions of the Restated Certificate of
     Incorporation, if any, may be declared by the Board of Directors at any
     regular or special meeting, pursuant to law.  Dividends may be paid in
     cash, in property, in promissory notes or in shares of the capital stock,
     subject to the provisions of the Restated Certificate of Incorporation and
     the laws of Delaware.

            (b)  Reserves.  Before payment of any dividend, there may be set
                 --------
     aside out of any funds of the Corporation available for dividends such sum
     or sums as the directors from time to time, in their absolute discretion,
     think proper as a reserve or reserves to meet contingencies, or for
     equalizing dividends, or for repairing or maintaining any property of the
     Corporation, or for such other purpose as the directors shall think
     conducive to the interest of the Corporation, and the directors may modify
     or abolish any such reserve in the manner in which it was created.

     5.7.  LOST, STOLEN OR DESTROYED CERTIFICATES.  No certificates for shares
           --------------------------------------
of stock of the Corporation shall be issued in place of any certificate alleged
to have been lost, stolen or destroyed, except upon production of such evidence
of the loss, theft or destruction and upon indemnification of the Corporation
and its agents to such extent and in such manner as the Board of Directors may
from time to time prescribe.

              ARTICLE VI. - MISCELLANEOUS MANAGEMENT PROVISIONS.
              ------------------------------------------------- 

     6.1.  CHECKS, DRAFTS AND NOTES.  All checks, drafts or orders for the
           ------------------------
payment of money, and all notes and acceptances of the Corporation shall be
signed by such officer or officers, agent or agents as the Board of Directors
may designate.

     6.2.  NOTICES.
           ------- 

            (a)  Notices to directors may, and notices to stockholders shall, be
     in writing and delivered personally or mailed to the directors or
     stockholders at their addresses appearing on the books of the Corporation.
     Notice by mail shall be deemed to be given at the time when the same shall
     be mailed. Notice to directors may also be given by telegram, telecopy or
     orally, by telephone or in person.
<PAGE>
 
                                     -17-

            (b)  Whenever any notice is required to be given under the
     provisions of the statutes or of the Restated Certificate of Incorporation
     of the Corporation or of these By-Laws, a written waiver of notice, signed
     by the person or persons entitled to said notice, whether before or after
     the time stated therein or the meeting or action to which such notice
     relates, shall be deemed equivalent to notice. Attendance of a person at a
     meeting shall constitute a waiver of notice of such meeting except when the
     person attends a meeting for the express purpose of objecting, at the
     beginning of the meeting, to the transaction of any business because the
     meeting is not lawfully called or convened.

     6.3. CONFLICT OF INTEREST.  No contract or transaction between the
          --------------------
Corporation and one or more of its directors or officers, or between the
Corporation and any other corporation, partnership, association, or other
organization in which one or more of its directors or officers are directors or
officers, or have a financial interest, shall be void or voidable solely for
this reason, or solely because the director or officer is present at or
participates in the meeting of the Board of Directors or committee thereof which
authorized the contract or transaction, or solely because his or their votes are
counted for such purpose, if: (i) the material facts as to his relationship or
interest and as to the contract or transaction are disclosed or are known to the
Board of Directors or the committee and the Board of Directors or committee in
good faith authorizes the contract or transaction by the affirmative vote of a
majority of the disinterested directors, even though the disinterested directors
be less than a quorum; or (ii) the material facts as to his relationship or
interest and as to the contract or transaction are disclosed or are known to the
stockholders of the Corporation entitled to vote thereon, and the contract or
transaction as specifically approved in good faith by vote of such stockholders;
or (iii) the contract or transaction is fair as to the Corporation as of the
time it is authorized, approved or ratified, by the Board of Directors, a
committee or the stockholders. Common or interested directors may be counted in
determining the presence of a quorum at a meeting of the Board of Directors or
of a committee which authorizes the contract or transaction.

     6.4.  VOTING OF SECURITIES OWNED BY THIS CORPORATION.  Subject always to
           ----------------------------------------------
the specific directions of the Board of Directors, (i) any shares or other
securities issued by any other corporation and owned or controlled by this
Corporation may be voted in person at any meeting of security holders of such
other corporation by the President of this Corporation if he is present at such
meeting, or in his absence by the Treasurer of this Corporation if he is present
at such meeting, and (ii) whenever, in the judgment of the President, it is
desirable for this Corporation to execute a 
<PAGE>
 
                                     -18-

proxy or written consent in respect to any shares or other securities issued by
any other corporation and owned by this Corporation, such proxy or consent shall
be executed in the name of this Corporation by the President, without the
necessity of any authorization by the Board of Directors, affixation of
corporate seal or countersignature or attestation by another officer, provided
that if the President is unable to execute such proxy or consent by reason of
sickness, absence from the United States or other similar cause, the Treasurer
may execute such proxy or consent. Any person or persons designated in the
manner above stated as the proxy or proxies of this Corporation shall have full
right, power and authority to vote the shares or other securities issued by such
other corporation and owned by this Corporation the same as such shares or other
securities might be voted by this Corporation.

     6.5.  INSPECTION OF BOOKS.  The stockholders of the Corporation, by a
           -------------------
majority vote at any meeting of stockholders duly called, or in case the
stockholders shall fail to act, the Board of Directors shall have power from
time to time to determine whether and to what extent and at what times and
places and under what conditions and regulations the accounts and books of the
Corporation (other than the stock ledger) or any of them, shall be open to
inspection of stockholders; and no stockholder shall have any right to inspect
any account or book or document of the Corporation except as conferred by
statute or authorized by the Board of Directors or by a resolution of the
stockholders.

                        ARTICLE VII. - INDEMNIFICATION.
                        ------------------------------ 

     7.1.  RIGHT TO INDEMNIFICATION.  Each person who was or is made a party or
           ------------------------
is threatened to be made a party to or is otherwise involved in any action, suit
or proceeding, whether civil, criminal, administrative or investigative (a
"Proceeding"), by reason of being or having been a director or officer of the
Corporation or serving or having served at the request of the Corporation as a
director, trustee, officer, employee or agent of another corporation or of a
partnership, joint venture, trust or other enterprise, including service with
respect to an employee benefit plan (an "Indemnitee"), whether the basis of such
proceeding is alleged action or failure to act in an official capacity as a
director, trustee, officer, employee or agent or in any other capacity while
serving as a director, trustee, officer, employee or agent, shall be indemnified
and held harmless by the Corporation to the fullest extent authorized by the
Delaware General Corporation Law, as the same exists or may hereafter be amended
(but, in the case of any such amendment, only to the extent that such amendment
permits the Corporation to provide broader indemnification rights than permitted
prior thereto) (as used in this Article VII, the "Delaware Law"), 
<PAGE>
 
                                     -19-

against all expense, liability and loss (including attorneys' fees, judgments,
fines, ERISA excise taxes or penalties and amounts paid in settlement)
reasonably incurred or suffered by such Indemnitee in connection therewith and
such indemnification shall continue as to an Indemnitee who has ceased to be a
director, trustee, officer, employee or agent and shall inure to the benefit of
the Indemnitee's heirs, executors and administrators; provided, however, that,
except as provided in Section 7.2 hereof with respect to Proceedings to enforce
rights to indemnification, the Corporation shall indemnify any such Indemnitee
in connection with a Proceeding (or part thereof) initiated by such Indemnitee
only if such Proceeding (or part thereof) was authorized by the Board of
Directors of the Corporation. The right to indemnification conferred in this
Article VII shall be a contract right and shall include the right to be paid by
the Corporation the expenses (including attorneys' fees) incurred in defending
any such Proceeding in advance of its final disposition (an "Advancement of
Expenses"); provided, however, that, if the Delaware Law so requires, an
Advancement of Expenses incurred by an Indemnitee shall be made only upon
delivery to the Corporation of an undertaking (an "Undertaking"), by or on
behalf of such Indemnitee, to repay all amounts so advanced if it shall
ultimately be determined by final judicial decision from which there is no
further right to appeal (a "Final Adjudication") that such Indemnitee is not
entitled to be indemnified for such expenses under this Article VII or
otherwise.

     7.2.  RIGHT OF INDEMNITEE TO BRING SUIT.  If a claim under Section 7.1
           ---------------------------------
hereof is not paid in full by the Corporation within sixty days after a written
claim has been received by the Corporation, except in the case of a claim for an
Advancement of Expenses, in which case the applicable period shall be twenty
days, the Indemnitee may at any time thereafter bring suit against the
Corporation to recover the unpaid amount of the claim. If successful in whole or
in part in any such suit, or in a suit brought by the Corporation to recover an
Advancement of Expenses pursuant to the terms of an Undertaking, the Indemnitee
shall be entitled to be paid also the expense of prosecuting or defending such
suit. In (i) any suit brought by the Indemnitee to enforce a right to
indemnification hereunder (but not in a suit brought by the Indemnitee to
enforce a right to an Advancement of Expenses) it shall be a defense that, and
(ii) in any suit by the Corporation to recover an Advancement of Expenses
pursuant to the terms of an Undertaking the Corporation shall be entitled to
recover such expenses upon a Final Adjudication that, the Indemnitee has not met
the applicable standard of conduct set forth in the Delaware Law. Neither the
failure of the Corporation (including its board of directors, independent legal
counsel, or its stockholders) to have made a determination prior to the
commencement of such suit that 
<PAGE>
 
                                     -20-

indemnification of the Indemnitee is proper in the circumstances because the
Indemnitee has met the applicable standard of conduct set forth in the Delaware
Law, nor an actual determination by the Corporation (including its board of
directors, independent legal counsel, or its stockholders) that the Indemnitee
has not met such applicable standard of conduct, shall create a presumption that
the Indemnitee has not met the applicable standard of conduct or, in the case of
such a suit brought by the Indemnitee, be a defense to such suit. In any suit
brought by the Indemnitee to enforce a right to indemnification or to an
Advancement of Expenses hereunder, or by the Corporation to recover an
Advancement of Expenses pursuant to the terms of an Undertaking, the burden of
proving that the Indemnitee is not entitled to be indemnified, or to such
Advancement of Expenses, under this Article VII or otherwise shall be on the
Corporation.

     7.3.  NON-EXCLUSIVITY OF RIGHTS.  The rights to indemnification and to the
           -------------------------
Advancement of Expenses conferred in this Article 7 shall not be exclusive of
any other right which any person may have or hereafter acquire under any
statute, the Corporation's Restated Certificate of Incorporation, By-Law,
agreement, vote of stockholders or disinterested directors or otherwise.

     7.4.  INSURANCE.  The Corporation may maintain insurance, at its expense,
           ---------
to protect itself and any director, officer, employee or agent of the
Corporation or another corporation, partnership, joint venture, trust or other
enterprise against any expense, liability or loss, whether or not the
Corporation would have the power to indemnify such person against such expense,
liability or loss under this Article VII or under the Delaware Law.

     7.5.  INDEMNIFICATION OF EMPLOYEES AND AGENTS OF THE CORPORATION.  The
           ----------------------------------------------------------
Corporation may, to the extent authorized from time to time by the Board of
Directors, grant rights to indemnification, and to the Advancement of Expenses,
to any employee or agent of the Corporation to the fullest extent of the
provisions of this Article VII with respect to the indemnification and
Advancement of Expenses of directors and officers of the Corporation.

                          ARTICLE VIII. - AMENDMENTS.
                          -------------------------- 

     8.1.  AMENDMENTS.  Subject always to any limitations imposed by the
           ----------
Corporation's Restated Certificate of Incorporation, these By-Laws may be
altered, amended, or repealed, or new By-Laws may be adopted, only by (i) the
affirmative vote of the holders of at least three-quarters (75%) of the
outstanding voting stock of the Corporation (in addition to any 
<PAGE>
 
                                     -21-

separate class vote that may be required pursuant to the terms of any then
outstanding preferred stock of the Corporation), or (ii) by resolution of the
Board of Directors duly adopted by not less than a majority of the directors
then constituting the full Board of Directors.

<PAGE>
 
<TABLE> 
<CAPTION> 
                                                                                                                         Exhibit 4.1

                                                      CUBIST Pharmaceuticals

<S>                                                                                                  <C> 
COMMON STOCK                                                                                           SEE REVERSE FOR 
                                                                                                     CERTAIN DEFINITIONS

THIS CERTIFICATE IS TRANSFERABLE         INCORPORATED UNDER THE LAWS OF THE STATE OF DELAWARE         CUSIP 229678 10 7
 IN BOSTON OR IN NEW YORK CITY

       THIS CERTIFIES THAT






       is the owner of

                         FULLY PAID AND NON-ASSESSABLE SHARES OF COMMON CAPITAL STOCK, $.001 PAR VALUE, OF
                                                   CUBIST PHARMACEUTICALS, INC.
transferable only on the books of the Corporation by the holder hereof in person or by duly authorized attorney upon surrender of
this Certificate and the shares represented hereby are issued under and subject to the laws of the State of Delaware and to the
Certificate of Incorporation and By-laws of the Corporation, all as amended from time to time. This certificate is not valid unless
countersigned and registered by the Transfer Agent and Registrar.

  IN WITNESS WHEREOF, the Corporation has caused this Certificate to be signed by the facsimile signatures of its duly authorized 
officers and a facsimile of its corporate seal to be hereunto affixed.

Dated:

             /s/ Thomas A. Shea                                                             /s/ Scott M. Rocklage
             Treasurer                                                                      President and Chief Executive Officer
</TABLE> 
<PAGE>
 
                         CUBIST PHARMACEUTICALS, INC.

     The Corporation has more than one class of stock authorized to be issued.
The Corporation will furnish without charge to each stockholder upon written
request, a copy of the full text of the preferences, voting powers,
qualifications and special and relative rights of the shares of each class of
stock (and any series thereof) authorized to be issued by the Corporation.

    The following abbreviations, when used in the inscription on the face of
this certificate, shall be construed as though they were written out in full
according to applicable laws or regulations:

    TEN COM - as tenants in common    UNIF GIFT MIN ACT........Custodian........
    TEN ENT - as tenants by the                         (Cust)          (Minor)
              entireties
    JT TEN  - as joint tenants with           Under Uniform Gifts to Minors
              right of survivorship           Act...............................
              and not as tenants in
              common   
              


    Additional abbreviations may also be used though not in the above list.


For value received,______________________ hereby sell, assign and transfer unto
  
   PLEASE INSERT SOCIAL SECURITY OR OTHER
      IDENTIFYING NUMBER OF ASSIGNEE
 ________________________________________
|________________________________________|


________________________________________________________________________________
 (PLEASE PRINT OR TYPEWRITE NAME AND ADDRESS, INCLUDING ZIP CODE, OF ASSIGNEE)

________________________________________________________________________________

________________________________________________________________________________

_________________________________________________________________________ shares
of the capital stock represented by the within Certificate, and do hereby 
irrevocably constitute and appoint

_______________________________________________________________________ Attorney
to transfer the said stock on the books of the within named Corporation with 
full power of substitution in the premises.



Dated, ____________________________


               (Signature) _____________________________________________________
                   NOTICE: THE SIGNATURE TO THIS ASSIGMENT MUST CORRESPOND WITH
                           THE NAME AS WRITTEN UPON THE FACE OF THE CERTIFICATE
                           IN EVERY PARTICULAR, WITHOUT ALTERATION OR
                           ENLARGEMENT OR ANY CHANGE WHATEVER.


Signature Guaranteed:______________________________________________________
                     ALL GUARANTEES MUST BE MADE BY A FINANCIAL INSTITUTION
                     (SUCH AS A BANK OR BROKER) WHICH IS A PARTICIPANT IN 
                     SECURITIES TRANSFER AGENTS MEDALLION PROGRAM ("STAMP").
                     THE NEW YORK STOCK EXCHANGE, INC. MEDALLION SIGNATURE
                     PROGRAM ("MSP") OR THE STOCK EXCHANGES MEDALLION PROGRAM 
                     ("SEMP") AND MUST NOT BE DATED. GUARANTEES BY A NOTARY
                     PUBLIC ARE NOT ACCEPTED.



<PAGE>
 
                           BINGHAM, DANA & GOULD LLP
                              150 FEDERAL STREET                  EXHIBIT 5.1
                       BOSTON, MASSACHUSETTS 02110-1726
                               TEL: 617-951-8000
                               FAX: 617-951-8736

                                                    September 16, 1996

Cubist Pharmaceuticals, Inc.
24 Emily Street
Cambridge, MA 02139

Dear Ladies and Gentlemen:

      We have acted as counsel for Cubist Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), in connection with the registration under the
Securities Act of 1933, as amended (the "Act"), of 2,000,000 shares and an
additional 300,000 shares which may be offered by the Company in order to cover
over-allotments, if any, of Common Stock, par value $.001 per share (the
"Shares"), pursuant to a Registration Statement on Form S-1 (as amended, the 
"Registration Statement"), initially filed with the Securities Exchange 
Commission on June 25, 1996.

      We have reviewed the corporate proceedings of the Company with respect to 
the authorization of the issuance of the Shares. We have also examined and 
relied upon originals or copies, certified or otherwise identified or 
authenticated to our satisfaction, of such corporate records, instruments, 
agreements or other documents of the Company, and certificates of officers of 
the Company as to certain factual matters, and have made such investigation of 
law and have discussed with officers and representatives of the Company such 
questions of fact, as we have deemed necessary or appropriate as a basis for the
opinions hereinafter expressed. In our examination, we have assumed the 
genuineness of all signatures, the conformity to the originals of all documents 
reviewed by us as copies, the authenticity and completeness of all original 
documents reviewed by us in original or copy form and the legal competence of 
each individual executing any document.

     We have also assumed that an Underwriting Agreement substantially in the 
form of Exhibit 1.1 to the Registration Statement by and among the Company and 
the underwriters named therein (the "Underwriting Agreement"), will have been 
duly executed and delivered pursuant to the authorizing votes of the Board of 
Directors of the Company and that the Shares will be sold and transferred only 
upon the payment therefor as

















<PAGE>
 
provided in the Underwriting Agreement. We have further assumed that the 
registration requirements of the Act and all applicable requirements of state 
laws regulating the sale of securities will have been duly satisfied.

     This opinion is limited solely to the Delaware General Corporation Law as 
applied by courts located in Delaware.

     Based upon and subject to the foregoing, we are of the opinion that the
Shares have been duly authorized, and when delivered and paid for in accordance
with the provisions of the Underwriting Agreement, will be validly issued, fully
paid and non-assessable.

     We hereby consent to the filing of this opinion as an exhibit to the
Registration Statement and to the reference to this firm under the heading
"Legal Matters" in the Registration Statement.


                                                  Very truly yours,

                                                  /s/ Bingham, Dana & Gould LLP
 
                                                  BINGHAM, DANA & GOULD LLP

                                             











<PAGE>
 
                                                                    EXHIBIT 10.1
                            Confidential Treatment
 
                     MASSACHUSETTS INSTITUTE OF TECHNOLOGY

                               LICENSE AGREEMENT

                                  (EXCLUSIVE)


















                                                       Date:____________________
<PAGE>
 
                                      (i)


Vers 11/1/91                                       LLN/sc: 5261.5730.Cubist.agt.
Patent/Ex                                          Date: November 4, 1992

                               TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                         PAGE
                                                         ----
          <S>  <C>                                       <C>
          PREAMBLE........................................1
          --------

          ARTICLES
          --------

          1    DEFINITIONS.................................1

          2    GRANT.......................................3

          3    DUE DILIGENCE...............................4
          
          4    ROYALTIES...................................5

          5    REPORTS AND RECORDS.........................6

          6    PATENT PROSECUTION..........................7

          7    INFRINGEMENT................................8

          8    PRODUCT LIABILITY...........................9

          9    EXPORT CONTROLS.............................9

          10   NON-USE OF NAMES............................10

          11   ASSIGNMENT..................................10

          12   DISPUTE RESOLUTION..........................10

          13   TERMINATION.................................11

          14   PAYMENTS, NOTICES AND OTHER
               COMMUNICATIONS..............................12

          15   MISCELLANEOUS PROVISIONS....................12
</TABLE>
<PAGE>
 
                                      -1-

     This Agreement is made and entered into this    day of         , 199 , (the
"Effective Date") by and between MASSACHUSETTS INSTITUTE OF TECHNOLOGY, a 
corporation duly organized and existing under the laws of the Commonwealth of 
Massachusetts and having its principal office at 77 Massachusetts Avenue, 
Cambridge, Massachusetts 02139, U.S.A. (hereinafter referred to as "M.I.T."), 
and CUBIST PHARMACEUTICALS, INC., a corporation duly organized under the laws of
Delaware and having its principal office c/o DSV Partners, 221 Nassau Street, 
Princeton, NJ 08542 (hereinafter referred to as "LICENSEE").


                                  WITNESSETH
                                  ----------

     WHEREAS, M.I.T. is the owner of certain PATENT RIGHTS (as later defined 
herein) relating to M.I.T. Case No. 5261, "Designing Compounds Specifically 
Inhibiting Ribonucleic Acid" by Paul R. Schimmel, and Case No. 5730, "Nucleic 
Acid Reduction and Transport" by Nassim Usman and J. Rebek, Jr. and has the 
right to grant licenses under said PATENT RIGHTS, subject only to a 
royalty-free, nonexclusive license heretofore granted to the United States 
Government.

     WHEREAS, M.I.T. desires to have the PATENT RIGHTS utilized in the public 
interest and is willing to grant a license thereunder;

     WHEREAS, LICENSEE has represented to M.I.T., to induce M.I.T. to enter into
this Agreement, that LICENSEE is knowledgeable with respect to the subject 
matter related to the LICENSED PRODUCTS(s) (as later defined herein) and/or the 
use of the LICENSED PROCESS(es) (as later defined herein) and that it shall 
commit itself to a thorough, vigorous and diligent program of exploiting the 
PATENT RIGHTS so that public utilization shall result therefrom; and

     WHEREAS, LICENSEE desires to obtain a license under the PATENT RIGHTS upon 
the terms and conditions hereinafter set forth.

     NOW, THEREFORE, in consideration of the premises and the mutual covenants 
contained herein, the parties hereto agrees as follows:


                            ARTICLE 1 - DEFINITIONS
                            -----------------------

     For the purposes of this Agreement, the following words and phrases shall 
have the following meanings:

     1.1  "LICENSEE" shall include a related company of CUBIC PHARMACEUTICALS, 
INC., the voting stock of which is directly or indirectly at least fifty Percent
(50%) owned or controlled by CUBIC PHARMACEUTICALS, INC., an organization which 
directly or indirectly controls more than Fifty Percent (50%) of the voting 
stock of CUBIST PHARMACEUTICALS,

<PAGE>
 
                                      -2-

INC. and an organization, the majority ownership of which is directly or 
indirectly common to the ownership of CUBIST PHARMACEUTICALS, INC.

     1.2  "PATENT RIGHTS" shall mean all of the following M.I.T. intellectual 
property:

     (a)    the United States and foreign patents and/or patent applications 
            listed in Appendices A and B;

     (b)    United States and foreign patents issued from the applications
            listed in Appendices A and B and from divisional and continuations
            of these applications;

     (c)    claims of U.S. and foreign continuations-in-part applications, and
            of the resulting patents, which are directed to subject matter
            specifically described in the U.S. and foreign applications listed
            in Appendices A and B;

     (d)    claims of all foreign patent applications, and of the resulting
            patents, which are directed to subject matter specifically described
            in the United States patents and/or patent applications described in
            (a), (b) or (c) above; and

     (e)    any reissues of United States patents described in (a), (b) or (c) 
            above.

     1.3  A "LICENSED PRODUCT" shall mean any product or part thereof which:

     (a)    is covered in whole or in part by an issued, unexpired valid claim 
            or a pending claim contained in the PATENT RIGHTS in the country in 
            which any such product or part thereof is made, used or sold; or

     (b)    is manufactured by using a process or is employed to practice a
            process which is covered in whole or in part by an issued, unexpired
            valid claim or a pending claim contained in the PATENT RIGHTS in the
            country in which any LICENSED PROCESS is used or in which such
            product or part thereof is used or sold.

     where a "valid claim" shall mean a claim of an unexpired patent contained 
in the PATENT RIGHTS so long as such claim shall not have been held invalid in
an unappealed or unappealable decision rendered by a court of competent
jurisdiction.

     1.4  A "LICENSED PROCESS" shall mean any process which is covered in whole 
or in part by an issued, unexpired claim or a pending claim contained in the 
PATENT RIGHTS.

     1.5  "NET SALES" shall mean LICENSEE's (and its sublicensees') billings for
LICENSED PRODUCTS and LICENSED PROCESSES produced hereunder less the sum of the 
following:

     (a)    ****************************************************

     (b)    **********************************************************
            **********************
 
     (c)    ************************************************

     (d)    *******************************************




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -3-

     *********************************************************************** 
********************************************************************************
**************************************** LICENSED PRODUCTS shall be considered 
"sold" when billed out or invoiced. "Net Sales" shall not include LICENSED 
PRODUCTS sold for clinical testing, research or development purposes.


                               ARTICLE 2 - GRANT
                               -----------------

     2.1  M.I.T hereby grants to LICENSEE the worldwide right and license to
make, have made, use, lease and sell the LICENSED PRODUCTS and to practice the
LICENSED PROCESSES to the end of the term for which the PATENT RIGHTS are
granted unless this Agreement shall be sooner terminated according to the terms
hereof.

     2.2  LICENSEE agrees that LICENSED PRODUCTS leased or sold in the United 
States shall be manufactured substantially in the United States.

     2.3  In order to establish a period of exclusivity for LICENSEE, M.I.T. 
hereby agrees that it shall not grant any other licensee to make, have made, 
use, lease and sell LICENSED PRODUCTS or to utilize LICENSED PROCESSES during 
the term of this agreement, except as provided in P 2.10 below.

     2.4  At the end of the exclusive period, the license granted hereunder 
shall become nonexclusive and shall extend to the end of the term or terms for 
which any PATENT RIGHTS are issued, unless sooner terminated as hereinafter 
provided.

     2.5  M.I.T. reserves the right to practice under the PATENT RIGHTS for its 
own noncommercial research purposes.

     2.6  LICENSEE shall have the right to enter into sublicensing agreements 
for the rights, privileges and licenses granted hereunder. Upon any termination 
of this Agreement, sublicensees' rights shall also terminate, subject to 
Paragraph 13.6 hereof.

     2.7  LICENSEE agrees that any sublicenses granted by it shall provide that 
the obligations to M.I.T. of Articles 2, 5, 7, 8, 9, 10, 12, 13, and 15 of this 
Agreement shall be binding upon the sublicensee as if it were a party to this 
Agreement. LICENSEE further agrees to attach copies of these Articles to 
sublicense agreements.

     2.8  LICENSEE agrees to forward to M.I.T. a copy of any and all sublicense 
agreements promptly upon execution by the parties.

     2.9  LICENSEE shall not receive from sublicenses anything of value in lieu 
of cash payments in consideration for any sublicense under this Agreement, 
without the express prior written permission of M.I.T.

     


                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
                                      -4-

     2.10 If at any time following five (5) years after the Effective Date of 
this Agreement, M.I.T. receives a bona fide request from a third party for a 
license under the PATENT RIGHTS for a LICENSED PRODUCT not directly competitive 
with any LICENSED PRODUCT then sold by or under development by LICENSEE ("Third 
Party's Field of Use") M.I.T. shall so notify LICENSEE and request that LICENSEE
enter into good faith negotiations with the third party for a sublicense to the 
PATENT RIGHTS in the Third Party's Field of Use. If such a sublicense has not 
been granted within six months after such notification, M.I.T. may negotiate 
with the third party to grant such a sublicense, provided that any sublicense 
granted by M.I.T. shall:

     (a)    Be confined to a single class of therapeutic products not
            competitive with any LICENSED PRODUCT under development or sold by
            LICENSEE at any time of granting of the sublicense; and

     (b)    Be nonexclusive; and

     (c)    Require the third party to commit to a development plan in the Third
            Party Field of Use committing a minimum of $250,000 per year in
            development funds beginning within six months of the granting of the
            sublicense; and

     (d)    Require running royalties no less than those specified for LICENSEE 
            in subparagraph 4.1 (c) below; and

     further provided that when M.I.T. and the third party have substantially 
agreed on sublicensing terms, LICENSEE shall have a forty-five (45) day first 
right of refusal to retain exclusivity in the Third Party Field of Use by 
matching the Third Party sublicensing terms (including committed development 
funds) but at a running royalty rate equal to that specified in subparagraph 4.1
(c) below.

     Any revenue derived by M.I.T. in the sublicensing of the PATENT RIGHTS as 
specified hereunder shall be shared equally between M.I.T. and LICENSEE.

     2.11 The license granted hereunder shall not be construed to confer any 
rights upon LICENSEE by implication, estoppel or otherwise as to any technology 
not specifically set forth in Appendix A hereof.

     2.12 Any improvements made by LICENSEE relating to the LICENSED PRODUCTS or
LICENSED PROCESSES shall be the property of LICENSEE and M.I.T. shall have no 
right, title or interest therein. Any improvements made by Dr. Paul R. Schimmel 
or Dr. Julius Rebek while performing services for LICENSEE using LICENSEE's 
facilities shall, contingent upon agreement between LICENSEE and Dr. Schimmel or
Dr. Rebek as the case may be, be considered to be an improvement made by 
LICENSEE.


                           ARTICLE 3 - DUE DILIGENCE
                           -------------------------

     3.1  LICENSEE shall use its best efforts to bring LICENSED PRODUCTS to 
market through a thorough, vigorous and diligent program for exploitation of the
PATENT RIGHTS and

<PAGE>
 
                                      -5-

to continue active, diligent development and marketing efforts for LICENSED 
PRODUCTS throughout the life of this Agreement.

     
     ************************************************************************
*******************************

     ************************************************************************
     *******************

     *************************************************************************
     **********************
 
     *************************************************************************
     **************** 

     3.3  LICENSEE's failure to perform in accordance with Paragraphs 3.1 and 
3.2 above shall be grounds for M.I.T. to terminate this Agreement pursuant to 
Paragraph 13.3 hereof.


                             ARTICLE 4 - ROYALTIES
                             ---------------------

     4.1  For the rights, privileges and license granted hereunder, LICENSEE 
shall pay royalties to M.I.T. in the manner hereinafter provided to the end of 
the term of the PATENT RIGHTS or until this Agreement shall be terminated:

     (a)    A License Issue Fee of ************************, which said 
            License Issue Fee shall be deemed earned and due in two parts:

            (i)     ****************************** due upon the signing of this
                    Agreement; and

            (ii)    ************************************* due upon the raising
                    of Two Million Dollars ($2,000,000) in investment capital by
                    LICENSEE.

     (b)    Licensee Maintenance Fees of ******************************* per
            year payable on January 1, 1994 and on January 1 of each year
            thereafter; provided, however, that Running Royalties subsequently
            due on NET SALES for each said year, if any, shall be creditable
            against the License Maintenance Fee for said year. **************
            *********************************

     (c)    Running Royalties in amount equal to **************** of NET SALES
            of the LICENSED PRODUCTS and LICENSED PROCESSES used, leased or sold
            by and/or for LICENSEE which require prescriptions to be sold and
            *************** of the NET SALES of other LICENSED PRODUCTS and
            LICENSED PROCESSES.

     (d)    A share of sublicensing revenue received by LICENSEE equal to:

            (i)     *********************** if only the PATENT RIGHTS are
                    sublicensed; or

            (ii)    ************************* if the sublicense revenue includes
                    revenue received for the PATENT RIGHTS sublicensed in
                    conjunction with products developed by LICENSEE and/or
                    substantial technology developed by LICENSEE, provided that
                    in no case shall the revenue paid to M.I.T. for each
                    sublicense be less than *********************** the LICENSED
                    PRODUCTS made, used or sold by that sublicensee




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
                                      -6-

     (e)    Shares of common stock of LICENSEE equal to ************ of the
            outstanding common and preferred shares of LICENSEE at the
            completion of the first round of equity of investment.

     (f)    Antidilution:
            ------------

            If, following the first round of equity funding, LICENSEE issues
            additional shares of stock that M.I.T.'s total share of outstanding
            stock falls below **************, then LICENSEE shall grant to
            M.I.T. additional shares such that M.I.T.'s fraction of total
            outstanding shares remains at ***********, until a total of
            *********************** funding is obtained by LICENSEE. Thereafter,
            no additional shares shall be due to M.I.T., provided that in
            subsequent rounds of financing, M.I.T. shall have the right to
            invest in additional shares, on a pro rata basis, at the same
                                              --------
            price as is granted to other investors holding common or preferred
            stock.

     4.2  All payments due hereunder shall be paid in full, without deduction of
taxes or other fees which may be imposed by any government and which shall be 
paid by LICENSEE.

     4.3  No multiple royalties shall be payable because any LICENSED PRODUCT, 
its manufacture, use, lease or sale are or shall be covered by more than one 
PATENT RIGHTS patent application or PATENT RIGHTS patent licensed under this 
Agreement.

     4.4  Royalty payments shall be paid in United States dollars in Cambridge, 
Massachusetts, or at such other place as M.I.T. may reasonably designate 
consistent with the laws and regulations controlling in any foreign country. If 
any currency conversion shall be required in connection with the payment of 
royalties hereunder, such conversion shall be made by using the exchange rate 
prevailing at the Chase Manhattan Bank (N.A.) on the last business day of the 
calendar quarterly reporting period to which such royalty payments relate.


                        ARTICLE 5 - REPORTS AND RECORDS
                        -------------------------------

     5.1  LICENSEE shall keep full, true and accurate books of account 
containing all particulars that may be necessary for the purpose of showing the 
amounts payable to M.I.T. hereunder. Said books of account shall be kept 
LICENSEE's principal place of business or the principal place of business of
the appropriate division of LICENSEE to which this Agreement relates. Said books
and the supporting data shall be open at all reasonable times for three (3) 
years following the end of the calendar year to which they pertain, to the 
inspection of M.I.T. or its agents for the purpose of verifying LICENSEE's 
royalty statement or compliance in other respects with this Agreement. Should 
such inspection lead to the discovery of a greater than ten Percent (10%) 
discrepancy in reporting, LICENSEE agrees to pay the full cost of such 
inspection.

     5.2  LICENSEE, within sixty (60) days after December 31 of each year prior 
to the first commercial sale of a LICENSED PRODUCT and sixty days after March 
31, June 30, September 30 and December 31, of each year after the first 
commercial sale of a LICENSED PRODUCT, shall deliver to M.I.T. true and accurate
reports, giving such particulars of the business conducted



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
                                      -7-

by LICENSEE and it sublicensees during the preceding three-month period under 
this Agreement as shall be pertinent to a royalty accounting hereunder. These 
shall include at least the following:

     (a)    number of LICENSED PRODUCTS manufactured and sold by LICENSEE and 
            all sublicensees;

     (b)    total billings for LICENSED PRODUCTS sold by LICENSEE and all 
            sublicensees;

     (c)    accounting for all LICENSED PROCESSES used or sold by LICENSEE and 
            all sublicensees;

     (d)    deductions applicable as provided in Paragraph 1.5;

     (e)    total royalties due; and

     (f)    names and addresses of all sublicensees of LICENSEE.

     5.3  With each such report submitted, LICENSEE shall pay to M.I.T. the 
royalties due and payable under this Agreement. If no royalties shall be due, 
LICENSEE shall so report.

     5.4  On or before the ninetieth (90th) day following the close of 
LICENSEE's fiscal year, LICENSEE shall provide M.I.T. with LICENSEE's certified 
financial statements for the preceding fiscal year including, at a minimum, a 
Balance Sheet and an Operating Statement.

     5.5  The royalty payments set forth in this Agreement and amounts due under
Article 6 shall, if overdue, bear interest until payment at a per annum rate two
Percent (2%) above the prime rate in effect at the Chase Manhattan Bank (N.A.) 
on the due date. The payment of such interest shall not foreclose M.I.T. from 
exercising any other rights it may have as a consequence of the lateness of any 
payment.


                        ARTICLE 6 - PATENT PROSECUTION
                        ------------------------------

     6.1  M.I.T. shall apply for, seek prompt issuance of, and maintain during 
the term of this Agreement the PATENT RIGHTS in the United States and, where 
legally possible, in those foreign countries listed in Appendix B hereto and in 
any other foreign country at LICENSEE's request. Appendix B may be amended by 
verbal agreement of both parties, such agreement to be confirmed in writing 
within ten (10) days. The prosecution, filing and maintenance of all PATENT 
RIGHTS patents and applications shall be primary responsibility of M.I.T.; 
provided, however, LICENSEE shall have reasonable opportunities to advise M.I.T.
and shall cooperate with M.I.T. in such prosecution, filing and maintenance.

     6.2  Payment of all fees and costs relating to the filing, prosecution, and
maintenance of the PATENT RIGHTS shall be the responsibility of LICENSEE, 
whether such fees and costs were incurred before or after the date of this 
Agreement.
<PAGE>
 
                                      -8-

                           ARTICLE 7 - INFRINGEMENT
                           ------------------------

     7.1  LICENSEE shall inform M.I.T. promptly in writing of any alleged 
infringement of the PATENT RIGHTS by a third party and of any available evidence
thereof.

     7.2  During the term of this Agreement, M.I.T. shall have the right, but 
shall not be obligated, to prosecute at its own expense all infringements of the
PATENT RIGHTS and, in furtherance of such right, LICENSEE, hereby agrees that 
M.I.T. may include LICENSEE as a party plaintiff in any such suit, without 
expense to LICENSEE. The total cost of any such infringement action commenced or
defended solely by M.I.T. shall be borne by M.I.T. and M.I.T. shall keep any 
recovery or damages for past infringement derived therefrom.

     7.3  If within six (6) months after having been notified of any alleged 
infringement, M.I.T. shall have been unsuccessful in persuading the alleged 
infringer to desist and shall not have brought and shall not be diligently 
prosecuting an infringement action, or if M.I.T. shall notify LICENSEE at any 
time prior thereto of its intention not to bring suit against any alleged 
infringer, then, and in those events only, LICENSEE shall have the right, but 
shall not be obligated, to prosecute at its own expense any infringement of the 
PATENT RIGHTS, and LICENSEE may, for such purposes, use the name of M.I.T. as 
party plaintiff; provided, however, that such right to bring such an 
infringement action shall remain in effect. No settlement, consent judgment or 
other voluntary, final disposition of the suit may be entered into without the 
consent of M.I.T., which consent shall not unreasonably be withheld or delayed. 
LICENSEE shall indemnify M.I.T. against any order for costs that may be made 
against M.I.T. in such proceedings.

     7.4  In the event that LICENSEE shall undertake the enforcement and/or 
defense of the PATENT RIGHTS by litigation, LICENSEE may withhold up to Fifty 
Percent (50%) of the payments otherwise thereafter due M.I.T. under Article 4 
hereunder and apply the same toward reimbursement of up to half of LICENSEE's 
expenses, including reasonable attorney's fees, in connection therewith. Any 
recovery of damages by LICENSEE for each such suit shall be applied first in 
satisfaction of any unreimbursed expenses and legal fees of LICENSEE relating to
such suit, and next toward reimbursement of M.I.T. for any payments under 
Article 4 past due or withheld and applied pursuant to this Article 7. The 
balance remaining from any such recovery shall be divided between LICENSEE and 
M.I.T. in the proportion *******.

     7.5  In the event that a declaratory judgment action alleging invalidity or
noninfringement of any of the PATENT RIGHTS shall be brought against LICENSEE, 
M.I.T., at its option, shall have the right, within thirty (30) days after 
commencement of such action, to intervene and take over the sole defense of the 
action at its own expense.

     7.6  In any infringement suit as either party may institute to enforce the 
PATENT RIGHTS pursuant to this Agreement, the other party hereto shall, at the 
request and expense of the party initiating such suit, cooperate in all respects
and, to the extent possible, have its employees testify




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -9-

when requested and make available relevant records, papers, information, 
samples, specimens, and the like.

     7.7  LICENSEE, during the exclusive period of this Agreement, shall have 
the sole right in accordance with the terms and conditions herein to sublicense 
any alleged infringer for future use of the PATENT RIGHTS. Any upfront fees as 
part of such a sublicense shall be treated per Article 4.


                         ARTICLE 8 - PRODUCT LIABILITY
                         -----------------------------

     8.1  LICENSEE shall at all times during the term of this Agreement and 
thereafter, indemnify, defend and hold M.I.T., its trustees, officers, employees
and affiliates, harmless against all claims and expenses, including legal 
expenses and reasonable attorneys' fees, arising out of the death of or injury 
to any person or persons or out of any damage to property and against any other 
claim, proceeding, demand, expense and liability of any kind whatsoever 
resulting from the production, manufacture, sale, use, lease, consumption or 
advertisement of the LICENSED PRODUCT(s) and/or LICENSED PROCESS(es) or arising 
from any obligation of LICENSEE hereunder.

     8.2  Prior to the first use of a LICENSED PRODUCT on humans, LICENSEE shall
obtain and carry in full force and effect liability insurance which shall 
protect LICENSEE and M.I.T. in regard to events covered by Paragraph 8.1 above.

     8.3  EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS AGREEMENT, M.I.T. 
MAKES NO REPRESENTATIONS AND EXTENDS NO WARRANTIES OF ANY KIND, EITHER EXPRESS 
OR IMPLIED, INCLUDING BUT NOT LIMITED TO WARRANTIES OF MERCHANTABILITY, FITNESS 
FOR A PARTICULAR PURPOSE, AND VALIDITY OF PATENT RIGHTS CLAIMS, ISSUED OR 
PENDING. NOTHING IN THIS AGREEMENT SHALL BE CONSTRUED AS A REPRESENTATION MADE 
OR WARRANTY GIVEN BY M.I.T. THAT THE PRACTICE BY LICENSEE OF THE LICENSE GRANTED
HEREUNDER SHALL NOT INFRINGE THE PATENT RIGHTS OF ANY THIRD PARTY.


                          ARTICLE 9 - EXPORT CONTROLS
                          ---------------------------

     It is understood that M.I.T. is subject to United States laws and 
regulations controlling the export of technical data, computer software, 
laboratory prototypes and other commodities (including the Arms Export Control 
Act, as amended and the Export Administration Act of 1979), and that its 
obligations hereunder are contingent on compliance with applicable United States
export laws and regulations. The transfer of certain technical data and 
commodities may require a license from the cognizant agency of the United States
Government and/or written assurances by LICENSEE that LICENSEE shall not export 
data or commodities to certain foreign countries
<PAGE>
 
                                     -10-

without prior approval of such agency. M.I.T. neither represents that a license 
shall not be required nor that, if required, it shall be issued.


                         ARTICLE 10 - NON-USE OF NAMES
                         -----------------------------

     Except as required by law, LICENSEE shall not use the names or trademarks 
of the Massachusetts Institute of Technology, nor any adaptation thereof, nor 
the names of any of its employees, in an advertising, promotional or sales 
literature without prior written consent obtained from M.I.T., or said employee,
in each case, except that LICENSEE may state that it is licensed by M.I.T. under
one or more of the patents and/or applications comprising the PATENT RIGHTS. 
LICENSEE, may, however, use the name of Dr. Paul R. Schimmel, Dr. Julius Rebek 
and/or any other employee of M.I.T. who is a consultant or member of an advisory
board of LICENSEE, with their permission, and provided, also, that their
affiliation with LICENSEE is identified.


                            ARTICLE 11 - ASSIGNMENT
                            -----------------------

     This Agreement is not assignable, except in the case where LICENSEE 
transfers its business relating to the subject matter hereof or transfers a 
subsidiary of LICENSEE, or a joint venture in which LICENSEE is a participant, 
or all of any other entity in which LICENSEE has a controlling interest, 
whereupon transferee shall acquire all of LICENSEE's benefits and obligations 
hereunder. Any other assignment shall be void.


                        ARTICLE 12 - DISPUTE RESOLUTION
                        -------------------------------

     12.1 Except for the right of either party to apply to a court of competent 
jurisdiction for a temporary restraining order, a preliminary injunction, or 
other equitable relief to preserve the status quo or prevent irreparable harm, 
and all claims, disputes or controversies arising under, out of, or in 
connection with the Agreement, including any dispute relating to patent validity
or infringement, which the parties shall be unable to resolve within sixty (60) 
days shall be mediated in good faith. The party raising such dispute shall 
promptly advise the other party of such claim, dispute or controversy in a 
writing which describes in reasonable detail the nature of such dispute. By not 
later than five (5) business days after the recipient has received such notice 
of dispute, each party shall have selected for itself a representative who shall
have the authority to bind such party, and shall additionally have advised the 
other party in writing of the name and title of such representative. By not 
later than ten (10) business days after the date of such notice of dispute, such
representatives shall schedule a date for a mediation hearing with the Cambridge
Dispute Settlement Center or Endispute Inc. in Cambridge, Massachusetts. The 
parties shall enter into good faith mediation and shall share the costs equally.
If the representatives of the parties have not been able to resolve the dispute 
within fifteen (15) business days after such mediation hearing, the
<PAGE>
 
                                     -11-

parties shall have the right to pursue any other remedies legally available to 
resolve such dispute in either the Courts of the Commonwealth of Massachusetts 
or in the United States District Court for the District of Massachusetts, to 
whose jurisdiction for such purposes M.I.T. and LICENSEE each hereby irrevocably
consents and submits.

     12.2 Notwithstanding the foregoing, nothing in this Article shall be 
construed to waive any rights or timely performance of any obligations existing 
under this Agreement.


                           ARTICLE 13 - TERMINATION
                           ------------------------

     13.1 If LICENSEE shall cease to carry on its business, this Agreement shall
terminate upon notice by M.I.T, except as provided in Article 11.

     13.2 Should LICENSEE fail to make any payment whatsoever due and payable to
M.I.T. hereunder, M.I.T. shall have the right to terminate this Agreement 
effective on thirty (30) days' notice unless LICENSEE shall make all such 
payments to M.I.T. within said thirty (30) day period. Upon the expiration of 
the thirty (30) day period, if LICENSEE shall not have made all such payments to
M.I.T., the rights, privileges and license granted hereunder shall automatically
terminate.

     13.3 Upon any material breach or default of this Agreement by LICENSEE, 
other than those occurrences set out in Paragraphs 13.1 and 13.2 hereinabove, 
which shall always take precedence in that order over any material breach or 
default referred to in this Paragraph 13.3, M.I.T. shall have the right to 
terminate this Agreement and the rights, privileges and license granted 
hereunder effective on ninety (90) days' notice to LICENSEE. Such termination 
shall become automatically effective unless LICENSEE shall have cured any such 
material breach or default prior to the expiration of the ninety (90) day 
period.

     13.4 LICENSEE shall have the right to terminate this Agreement at any time 
on six (6) months' notice to M.I.T., and upon payment of all amounts due M.I.T. 
through the effective date of the termination.

     13.5 Upon termination of this Agreement for any reason, nothing herein
shall be construed to release either party from any obligation that matured
prior to the effective date of such termination. LICENSEE and any sublicensee
thereof may, however, after the effective date of such termination, sell all
LICENSED PRODUCTS, and complete LICENSED PRODUCTS in the process of manufacture
at the time of such termination and sell the same, provided that LICENSEE shall
pay to M.I.T. the Running Royalties thereon as required by Article 4 of this
Agreement and shall submit the reports required by Article 5 hereof on the sales
of LICENSED PRODUCTS.

     13.6 Upon termination of this Agreement for any reason, any sublicensee not
then in default shall have the right to seek a license from M.I.T. M.I.T. agrees
to negotiate such licenses in good faith under reasonable terms and conditions.
<PAGE>
 
                                     -12-

                        ARTICLE 14 - PAYMENTS, NOTICES
                        ------------------------------
                            AND OTHER COMMUNICATIONS
                            -----------------------

     Any payment, notice or other communication pursuant to this Agreement shall
be sufficiently made or given on the date of mailing if sent to such party by 
certified first class mail, postage prepaid, addressed to it as its address 
below or as it shall designate by written notice given to the other party:

     In the case of M.I.T.:

                         Director
                         Technology Licensing Office
                         Massachusetts Institute of Technology
                         Room E32-300
                         Cambridge, Massachusetts 02139

     In the case of LICENSEE:

                         President
                         Cubist Pharmaceuticals, Inc.
                         c/o DSV Partners
                         221 Nassau Street
                         Princeton, NJ 08542


                     ARTICLE 15 - MISCELLANEOUS PROVISIONS
                     -------------------------------------

     15.1 This Agreement shall be construed, governed, interpreted and applied 
in accordance with the laws of the Commonwealth of Massachusetts, U.S.A., except
that questions affecting the construction and effect of any patent shall be 
determined by the law of the country in which the patent was granted.

     15.2 The parties hereto acknowledge that this Agreement sets forth the 
entire Agreement and understanding of the parties hereto as to the subject 
matter hereof, and shall not be subject to any change or modification except by 
the execution of a written instrument subscribed to by the parties hereto.

     15.3 The provisions of this Agreement are severable, and in the event that 
any provisions of this Agreement shall be determined to be invalid or 
unenforceable under any controlling body of the law, such invalidity or 
unenforceability shall not in any way affect the validity or enforceability of 
the remaining provisions hereof.

     15.4 LICENSEE agrees to mark the LICENSED PRODUCTS sold in the United 
States with all applicable United States patent numbers. All LICENSED PRODUCTS 
shipped to or sold in other countries shall be marked in such a manner as to 
conform with the patent laws and practice of the country of manufacture or sale.
<PAGE>
 
                                     -13-

     15.5 The failure of either party to assert a right hereunder or to insist 
upon compliance with any term or condition of this Agreement shall not 
constitute a waiver of that right or excuse a similar subsequent failure to 
perform any such term or condition by the other party.

     IN WITNESS WHEREOF, the parties have duly executed this Agreement the day 
and year set forth below.

MASSACHUSETTS INSTITUTE OF TECHNOLOGY

By /s/ John T. Preston
   ----------------------------------
Name   JOHN T. PRESTON, DIRECTOR
    ---------------------------------
Title  TECHNOLOGY LICENSING OFFICE   
     --------------------------------

Date  11-5-92
    --------------------------------- 


CUBIST PHARMACEUTICALS, INC.

By /s/ John K. Clarke
  -----------------------------------
Name   JOHN K. CLARKE
    ---------------------------------
Title  PRESIDENT & CEO
     --------------------------------
Date   11-17-92
     --------------------------------
<PAGE>
 
                                     -14-

                                  APPENDIX A
                                  ----------


UNITED STATES PATENT RIGHTS
- ---------------------------

M.I.T. Case No. 5261
"Designing Compounds Specifically Inhibiting Ribonucleic Acid"
U.S.S.N. 586,534
By Paul R. Schimmel
Filed on 9/21/90

M.I.T. Case No. 5730
"Nucleic Acid Reduction and Transport"
By Nasim Usman and J. Rebek, Jr.
U.S.S.N. 930,087
Filed on 8/14/92

<PAGE>
 
                                     -15-

                                  APPENDIX B
                                  ----------



     Foreign countries in which PATENT RIGHTS for M.I.T. Case No. 5730 shall be 
filed, prosecuted and maintained in accordance with Article 6:

                          Canada
                          Great Britain
                          France
                          Germany
                          Italy
                          Japan


<PAGE>
 
                                FIRST AMENDMENT

This Amendment with the effective date of January 20, 1995, is to the License 
Agreement dated November 4, 1992 between CUBIST PHARMACEUTICALS, INC. and 
MASSACHUSETTS INSTITUTE OF TECHNOLOGY.

The parties thereto now further agree as follows:

1.   The PATENT RIGHTS of M.I.T. Case 6299 "Specific tRNA Binding-Dependent 
Inhibition of Growth of Microbial Pathogens" by Paul R. Schimmel and Eric T. 
Schmidt shall be added to the PATENT RIGHTS of the License Agreement. These 
include as of the date of this Amendment:

          U.S.S.N. 068362     Filed 05/28/93
          PCT/US94/05905      Filed 05/25/94
          USSN PCT            Filed 05/25/94 as CIP of 06382

2.   Cubist will reimburse M.I.T. for all costs incurred in the filing and 
prosecution of the PATENT RIGHTS of M.I.T. Case 6299 whether incurred before or 
after the effective date of this Amendment.

Agreed to for:

MASSACHUETTS INSTITUTE OF TECHNOLOGY         CUBIST PHARMACEUTICALS, INC.
By /s/ Lita Nelsen                           By /s/ Scott M. Rocklage
  ----------------------------------           --------------------------
Name  LITA L. NELSEN, DIRECTOR               Name Scott M. Rocklage
    --------------------------------             ------------------------
Title TECHNOLOGY LICENSING OFFICE            Title President & CEO
     -------------------------------              -----------------------
Date  Jan 17, 1995                           Date  1/19/95
     -------------------------------              -----------------------
<PAGE>
 
[LETTERHEAD APPEARS HERE]

                               SECOND AMENDMENT


This Amendment with the effective date of May 17, 1995, is to the License 
Agreement dated November 4, 1992 between CUBIST PHARMACEUTICALS, INC. and 
MASSACHUSETTS INSTITUTE OF TECHNOLOGY.

The parties thereto now further agree as follows:

1.   The PATENT RIGHTS of M.I.T. Case 6299 "Specific tRNA Binding-Dependent 
Inhibition of Growth of Microbial Pathogens" by Paul R. Schimmel and Eric T. 
Schmidt shall be deleted from the PATENT RIGHTS of the License Agreement. These
include as of the date of this Amendment:

          USSN 08/068362      Filed 05/28/93
          PCT/US94/05905      Filed 05/25/94
          USSN PCT            Filed 05/25/94

2.   The PATENT RIGHTS of M.I.T. Case 5730 "Nucleic Acid Recognition and 
Transport" by Julius Rebek, Jr., Nassim Usman, and Javier deMendoza shall be 
deleted from the PATENT RIGHTS of the License Agreement. These include as of the
date of this Amendment:

          USSN 07/930,087     Filed 08/14/92
          PCT/US93/07603      Filed 08/13/93

3.   The PATENT RIGHTS of M.I.T. Case 5261 "Designing Compounds Specifically 
Inhibiting Ribonucleic Acid" by Paul R. Schimmel and Karin Musier-Forsyth are 
retained under the Patent Rights of the License Agreement. These include as of 
the date of this Amendment:

          USSN 07/586,534     Filed 09/21/90
          USSN 07/929,834     Filed 08/14/92
          USSN 08/129,787     Filed 09/29/93

4.   The License Maintenance Fees under Paragraph 4.1 (b) on page 5 of the 
License Agreement are amended as follows:

     License Maintenance Fees of ****************************
     ********* per year payable on January 1 of the year following the
                                             -------------------------
     issuance of a Valid Claim under the Patent Rights and on January
     -------------------------------------------------
     1 of each year thereafter; provided that such Valid Claim includes
                                ---------------------------------------




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
     the intended scope of one or both of Claim 1 and Claim 3, as
     ------------------------------------------------------------
     originally filed, and also provided, however, that Running
     ----------------
     Royalties subsequently due on NET SALES for each said year, if 
     any, shall be creditable against the License Maintenance Fee for 
     said year.*******************************************************
     *****************************************************************
     *****************************************************************

Agreed to for:

MASSACHUSETTS INSTITUTE OF TECHNOLOGY          CUBIST PHARMACEUTICALS, INC.

By:     /s/ Lita Nelsen                        By:     /s/ Scott M. Rocklage
        -------------------------------------          -------------------------

Name:   Lita L. Nelsen                         Name:   Scott M. Rocklage, Ph.D.
        -------------------------------------          -------------------------

Title:  Director, Technology Licensing office  Title:  President & CEO
        -------------------------------------          -------------------------

Date:   8/2/95                                 Date:   7/25/95
        -------------------------------------          -------------------------









                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                            Confidential Treatment
 
                     MASSACHUSETTS INSTITUTE OF TECHNOLOGY

                                      AND

                         CUBIST PHARMACEUTICALS, INC.

                           PATENT LICENSE AGREEMENT

                                    7/21/94   

                                  (EXCLUSIVE)
<PAGE>
 
6-8-94                                                  LLN/sc; 6484. Cubist.agt
Patent Exclusive                             (Date last modified: July 18, 1994)

<TABLE>
<CAPTION>
                               TABLE OF CONTENTS
                               -----------------
     <S>                                                               <C>
     WITNESSETH.......................................................  1
     1  - DEFINITIONS.................................................  2
     2  - GRANT.......................................................  3
     3  - DILIGENCE...................................................  4
     4  - ROYALTIES...................................................  5
     5  - REPORTS AND RECORDS.........................................  6
     6  - PATENT PROSECUTION..........................................  7
     7  - INFRINGEMENT................................................  8
     8  - PRODUCT LIABILITY...........................................  9
     9  - EXPORT CONTROLS............................................. 10
     10 - NON-USE OF NAMES............................................ 10
     11 - ASSIGNMENT.................................................. 11
     12 - DISPUTE RESOLUTION.......................................... 11
     13 - TERMINATION................................................. 11
     14 - PAYMENTS, NOTICES AND OTHER COMMUNICATIONS.................. 12
     15 - MISCELLANEOUS PROVISIONS.................................... 13
     APPENDIX A....................................................... 15
     APPENDIX B....................................................... 16
</TABLE>
<PAGE>
 
                     MASSACHUSETTS INSTITUTE OF TECHNOLOGY

                                     and 

                         CUBIST PHARMACEUTICALS, INC.

                           PATENT LICENSE AGREEMENT


     This Agreement is made and entered into this  21 day of     July   , 1994, 
                                                  ----       ----------   -----
(the "EFFECTIVE DATE") by and between the MASSACHUSETTS INSTITUTE OF TECHNOLOGY,
a corporation duly organized and existing under the laws of the Commonwealth of 
Massachusetts and having its principal office at 77 Massachusetts Avenue, 
Cambridge, Massachusetts 02139, U.S.A. (hereinafter referred to as "M.I.T."), 
and CUBIST PHARMACEUTICALS, INC.,  a corporation duly organized under the laws 
of   Delaware   and having its principal office at 24 Emily St., Cambridge, MA 
   ------------
02139 (hereinafter referred to as "LICENSEE").


                                  WITNESSETH
                                  ----------
     WHEREAS, M.I.T. is the owner of certain PATENT RIGHTS (as later defined 
herein) relating to M.I.T. Case No. 6484, "Process for Creating Molecular 
Diversity" by Julius Rebek, Jr., Thomas Carell and Edward Wintner and has the 
right to grant licenses under said PATENT RIGHTS, subject to a royalty-free, 
nonexclusive license heretofore granted to the United States Government;
     
     WHEREAS, M.I.T. desires to have the PATENT RIGHTS developed and 
commercialized to benefit the public and is willing to grant a license 
thereunder;
     
     WHEREAS, LICENSEE has represented to M.I.T., to induce M.I.T. to enter into
this Agreement, that LICENSEE is experienced in the development, production, 
manufacture, marketing and sale of products similar to the LICENSED PRODUCT(s) 
(as later defined herein) and/or the use of the LICENSED PROCESS(es) (as later 
defined herein) and that it shall commit itself to a thorough, vigorous and 
diligent program of exploiting the PATENT RIGHTS so that public utilization 
shall result therefrom; and
     
     WHEREAS, LICENSEE desires to obtain a license under the PATENT RIGHTS upon 
the terms and conditions hereinafter set forth.
     
     NOW, THEREFORE, in consideration of the premises and the mutual covenants 
contained herein, the parties hereto agree as follows:

                                      -1-
<PAGE>
 
                                1 - DEFINITIONS
                                ---------------

     For the purposes of this Agreement, the following words and phrases shall 
have the following meanings:

     1.1  "LICENSEE" shall include a related company of CUBIST PHARMACEUTICALS, 
INC., the voting stock of which is directly or indirectly at least fifty 
percent (50%) owned or controlled by CUBIST PHARMACEUTICALS, INC., an 
organization which directly or indirectly controls more than fifty percent 
(50%) of the voting stock of CUBIST PHARMACEUTICALS, INC. and an organization, 
the majority ownership of which is directly or indirectly common to the 
ownership of CUBIST PHARMACEUTICALS, INC.

     1.2  "PATENT RIGHTS" shall mean all of the following M.I.T. intellectual 
property:

          a.   the United States patents listed in Appendix A;

          b.   the United States patent applications listed in Appendix A, and
               divisionals, continuations and claims of continuation-in-part
               applications which shall be directed to subject matter
               specifically described in such patent applications, and the
               resulting patents;

          c.   any patents resulting from reissues or reexaminations of the 
               United States patents described in a. and b. above;

          d.   the Foreign patents listed in Appendix A;

          e.   the Foreign patent applications listed in Appendix A, and
               divisionals, continuations and claims of continuation-in-part
               applications which shall be directed to subject matter
               specifically described in such Foreign patent applications, and
               the resulting patents;

          f.   Foreign patent applications filed after the EFFECTIVE DATE in the
               countries listed in Appendix B and divisionals, continuations and
               claims of continuation-in-part applications which shall be
               directed to subject matter specifically described in such patent
               applications, and the resulting patents; and

          g.   any Foreign patents, resulting from equivalent Foreign procedures
               to United States reissues and reexaminations, of the Foreign
               patents described in d., e. and f. above.

     1.3  A "LICENSED PRODUCT" shall mean any product or part thereof which:

          a.   is covered in whole or in part by an issued, unexpired claim or a
               pending claim contained in the PATENT RIGHTS in the country in
               which any such product or part thereof is made, used or sold; or

          b.   is manufactured by using a process or is employed to practice a
               process which is covered in whole or in part by an issued,
               unexpired claim or a pending claim contained in the PATENT RIGHTS
               in the country in which any LICENSED PROCESS is used or in which
               such product or part thereof is used or sold.

<PAGE>
 
     1.4  A "LICENSED PROCESS" shall mean any process which is covered in whole 
or in part by an issued, unexpired claim or a pending claim contained in the 
PATENT RIGHTS. 

     1.5  "NET SALES" shall mean LICENSEE's and its sublicensees' billings for 
LICENSED PRODUCTS and LICENSED PROCESSES less the sum of the following:

          ********************************************************************* 
************************************************************************

          *********************************************************************
******************************

          ****************************************************

          ********************************************

     *********************************************************************** 
********************************************************************************
**************************************** NET SALES shall occur when a LICENSED 
PRODUCT or LICENSED PROCESS shall be invoiced. If a LICENSED PRODUCT or 
LICENSED PROCESS shall be distributed or invoiced for a discounted price 
substantially lower than customary in the trade or distributed at no cost to 
affiliates or otherwise, NET SALES shall be based on the customary amount billed
for such LICENSED PRODUCTS or LICENSED PROCESSES.

     1.6  "TERRITORY" shall mean worldwide.

     1.7  "FIELD OF USE" shall mean all fields except autoimmune disease and 
endogenous immune disorders.

                                   2 - GRANT
                                   ---------

     2.1  M.I.T. hereby grants to LICENSEE the exclusive right and license in 
the TERRITORY for the FIELD OF USE to practice under the PATENT RIGHTS and, to 
the extent not prohibited by other patents, to make, have made, use, lease, sell
and import LICENSED PRODUCTS and to practice the LICENSED PROCESSES, until the 
expiration of the last to expire of the PATENT RIGHTS, unless this Agreement 
shall be sooner terminated according to the terms hereof.

     2.2  LICENSEE agrees that LICENSED PRODUCTS leased or sold in the United 
States shall be manufactured substantially in the United States.

     2.3  M.I.T. also grants to LICENSEE the rights to use the Tangible Property
in research, development and commercial production.

     2.4  M.I.T. reserves the right to practice under the PATENT RIGHTS for 
noncommercial research purposes and to grant the right to other non-profit 
organizations to practice under the PATENT RIGHTS for noncommercial academic 
publishable research purposes.



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission




<PAGE>
 
     2.5  LICENSEE shall have the right to enter into sublicensing agreements 
for the rights, privileges and licenses granted hereunder. Upon any termination 
of this Agreement, sublicensees' rights shall also terminate, subject to 
Paragraph 13.6 hereof.

     2.6  LICENSEE agrees to incorporate Articles 2,5,7,8,9,10,12,13 and 15 of 
this Agreement into its sublicense agreements, so that these Articles shall be 
binding upon such sublicensees as if they were parties to this Agreement.

     2.7  LICENSEE agrees to forward to M.I.T. a copy of any and all sublicense 
agreements promptly upon execution by the parties.

     2.8  LICENSEE shall not receive from sublicensees anything of value in lieu
of cash payments in consideration for any sublicense under this Agreement, 
without the express prior written permission of M.I.T. 

     2.9  Nothing in this Agreement be construed to confer any rights upon 
LICENSEE by implication, estoppel or otherwise as to any technology, other than
the chemical libraries discussed in P.4.1 or to patent rights of M.I.T. or any 
other entity other than the PATENT RIGHTS, regardless of whether such patent 
rights shall be dominant or subordinate to any PATENT RIGHTS.


                                 3 - DILIGENCE
                                 -------------

     3.1  LICENSEE shall use its best efforts to bring one or more LICENSED 
PRODUCTS or LICENSED PROCESSES to market through a thorough, vigorous and 
diligent program for exploitation of the PATENT RIGHTS and to continue active, 
diligent marketing efforts for one or more LICENSED PRODUCTS or LICENSED 
PROCESSES throughout the life of this Agreement. LICENSEE shall maintain a 
technical staff of chemists and other qualified professionals capable of 
developing the technology of the PATENT RIGHTS.

     3.2  LICENSEE shall deliver to M.I.T. on or before December 31, 1994
************************************************************************** of
the LICENSED PRODUCTS and LICENSED PROCESSES and shall provide similar reports
to M.I.T. on or before December 31 of each year.

     3.3 LICENSEE and M.I.T. recognize that the technology of the PATENT RIGHTS
may have utility in many sub-fields of use other than those in the interest of
LICENSEE to develop. LICENSEE therefore agrees to make diligent efforts to
sublicense the PATENT RIGHTS under reasonable terms to third parties to
encourage development of these other field. Also, if M.I.T. brings to LICENSEE a
third party interested in sublicensing in a sub-field not competitive with
LICENSEE's products or development programs and not previously exclusively
sublicensed to others, LICENSEE shall negotiate in good faith towards granting a
sublicense to the third party under reasonable terms.



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission



<PAGE>
 
     3.4  LICENSEE's failure to perform in accordance with Paragraphs 3.1 and 
3.2 above shall be grounds for M.I.T. to terminate this Agreement pursuant to 
Paragraph 13.3 hereof. LICENSEE's failure to perform in accordance with P.3.3 
shall be grounds for M.I.T. to terminate the exclusivity of this Agreement.

     3.5  It is understood that Prof. Julius Rebek of M.I.T. has delivered to 
ProCept, Inc. one or more chemical libraries prepared according to the 
technology of the PATENT RIGHTS. LICENSEE shall use good faith efforts to 
negotiate a sublicense with ProCept in the field of use of "Action on CD4 and/or
CD8 receptors for anti-viral therapy and/or vaccines." If LICENSEE and ProCept 
are unable to reach a satisfactory sublicensing agreement within four (4) months
of the Effective Date of this Agreement, the dispute shall be subject to
mediation according to Article 12, provided that ProCept is willing to agree to
his mediation.

                                 4 - ROYALTIES
                                 -------------

     4.1  For the rights, privileges and license granted hereunder, LICENSEE 
shall pay royalties to M.I.T. in the manner hereinafter provided to the end of 
the term of the PATENT RIGHTS or until this Agreement shall be terminated:

          a.   License Issue Fee of ****************************************
               which said License Issue Fee shall be deemed earned and due
               immediately upon the EFFECTIVE DATE.

          b.   License Maintenance Fees of ****************************
               ********* per year payable on January 1, 1996 and on January 1 of
               each year thereafter; provided, however, that Running Royalties
               subsequently due on NET SALES for each said year, if any, shall
               be creditable against the License Maintenance Fee for said year.
               ************************************************************
               **************************************************************
               License Maintenance fees shall increase to **********************
               ********* per year beginning January 1 after the issuance of the
               first patent of the PATENT RIGHTS.

          c.   ******************** of revenues received for sublicensing of the
               Patent Rights and for the sale, lease or sublicensing of chemical
               libraries or portions thereof prepared by the technology of the
               PATENT RIGHTS, excluding running royalties received from
               sublicensees subject to subparagraph 4.1(d) below.

          d.   ************************* of any running royalties derived from
               sublicensees based on products discovered using the technology
               of the PATENT RIGHTS or chemical libraries made by LICENSEE or
               M.I.T. using the technology of the PATENT RIGHTS, provided,
               however, that if a LICENSED PRODUCT sold by a sublicensee is
               covered by an issued claim of the PATENT RIGHTS, the running
               royalties received by M.I.T. shall be no less than ***********
               **** of sublicensees net sales.

          e.   ****************************** Tangible Property Fee for each new
               chemical library or portion thereof made at M.I.T. under the
               supervision of Prof. Julius Rebek and delivered to LICENSEE after
               August 1, 1994. Preparation and delivery of such libraries shall
               be solely at the discretion of Prof. Rebek and



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
               shall be subject to any rights M.I.T. may have granted to
               sponsors of research at M.I.T. It is understood that one or more
               libraries have been prepared and delivered to LICENSEE prior to
               July 1, 1994. No Tangible Property Fee is due for these earlier
               delivered libraries provided that this Agreement is executed and
               in effect.

          f.   Running Royalties in an amount equal to **************** of NET
               SALES of LICENSED PRODUCTS covered by an issued claim of the
               PATENT RIGHTS which are leased or sold by and/or for LICENSEE. No
               running royalties shall be due on commercial products sold by
               LICENSEE which are not covered by an issued claim.

     4.2  All payments due hereunder shall be paid in full, without deduction of
taxes or other fees which my be imposed by any government, except as otherwise 
provided in Paragraph 1.5(b).

     4.3  No multiple royalties shall be payable because any LICENSED PRODUCT,
its manufacture, use, lease or sale are or shall be covered by more than one
PATENT RIGHTS patent application or PATENT RIGHTS patent licensed under this
Agreement.

     4.4  Royalty payments shall be paid in United States dollars in Cambridge, 
Massachusetts, or at such other place as M.I.T. may reasonably designate 
consistent with the laws and regulations controlling in any foreign country. If 
any currency conversion shall be required in connection with the payment or 
royalties hereunder, such conversion shall be made by using the exchange rate 
prevailing at the Chase Manhattan Bank (N.A.) on the last business day of the 
calender quarterly reporting period to which such royalty payments relate.

                            5 - REPORTS AND RECORDS
                            -----------------------

     5.1  LICENSEE shall keep full, true and accurate books of account 
containing all particulars that may be necessary for the purpose of showing the 
amounts payable to M.I.T. hereunder. Said books of account shall be kept at 
LICENSEE's principal place of business or the principal place of business of the
appropriate division of LICENSEE to which this Agreement relates. Said books and
the supporting data shall be open at all reasonable times for five (5) years 
following the end of the calender year to which they pertain, to the inspection 
of M.I.T. or its agents for the purpose of verifying LICENSEE's royalty
statement or compliance in other respects with this Agreement. Should such
inspection lead to the discovery of a greater than ten percent (10%) discrepancy
in reporting to M.I.T.'s detriment, LICENSEE agrees to pay the full cost of such
inspection.

     5.2  LICENSEE shall deliver to M.I.T. true and accurate reports, giving 
such particulars of the business conducted by LICENSEE and its sublicensses 
under this Agreement as shall be pertinent to a royalty accounting hereunder;



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
          a.   before the first commercial sale of a LICENSED PRODUCT or 
               LICENSED PROCESS, annually, on January 31 of each year; and

          b.   after the first commercial sale of a LICENSED PRODUCT or LICENSED
               PROCESS, quarterly, within sixty (60) days after March 31, June
               30, September 30 and December 31, of each year.

     These reports shall include at least the following:

          a.   number of LICENSED PRODUCTS manufactured, leased and sold by 
               and/or for LICENSEE and all sublicensees;

          b.   total invoices for LICENSED PRODUCTS manufactured, leased, and 
               sold by and/or for LICENSEE and all sublicensees;

          c.   accounting for all LICENSED PROCESSES used or sold by and/or for
               LICENSEE and all sublicensees;

          d.   accounting for NET SALES, noting the deductions applicable as 
               provided in Paragraph 1.5;

          e.   Running Royalties due under Paragraph 4.1(f);

          f.   names and addresses of all sublicensees of LICENSEE;

          g.   royalties due on payments from sublicensees; and

          h.   total royalties due.

     5.3  With each such report submitted, LICENSEE shall pay to M.I.T. the 
royalties due and payable under this Agreement. If no royalties shall be due, 
LICENSEE shall so report.

     5.4 On or before the ninetieth (90th) day following the close of LICENSEE's
fiscal year, LICENSEE shall provide M.I.T. with LICENSEE's certified financial
statements for the preceding fiscal year including, at a minimum, a balance
sheet and an income statement.

     5.5  The royalty payments set forth in this Agreement and amounts due under
Article 6 shall, if overdue, bear interest until payment at a per annum rate two
percent (2%) above the prime rate in effect at the Chase Manhattan Bank (N.A.) 
on the due date. The payment of such interest shall not foreclose M.I.T. from 
exercising any other rights it may have as a consequence of the lateness of any 
payment.

                            6 - PATENT PROSECUTION
                            ----------------------

     6.1 M.I.T. shall apply for, seek prompt issuance of, and maintain the
PATENT RIGHTS during the term of this Agreement. Appendix B is a list of the
foreign countries in which patent applications corresponding to the United
States Patent applications listed in Appendix A shall be filed. Appendix B may
be amended by mutual agreement of both parties. The filing, prosecution and
maintenance of all PATENT RIGHTS applications and patents shall be the primary
<PAGE>
 
responsibility of M.I.T.; provided, however, LICENSEE shall have reasonable 
opportunities to advise M.I.T. and shall cooperate with M.I.T. in such filing, 
prosection and maintenance.

     6.2 LICENSEE shall reimburse M.I.T. for eighty percent (80%) of all fees
and costs relating to the filing, prosecution and maintenance of the PATENT
RIGHTS, whether such fees and costs were incurred before or after the EFFECTIVE
DATE, provided, however, that if after December 31, 1994, if M.I.T. has in
effect no other license to the PATENT RIGHTS, LICENSEE shall reimburse M.I.T.
one hundred percent (100%) of patent fees and costs incurred thereafter. If
M.I.T. subsequently grants a license to a third party, LICENSEE shall be
reimbursed for twenty percent (20%) of costs incurred during LICENSEE's sole-
licensee period after December 31, 1994.

                               7 - INFRINGEMENT
                               ----------------

     7.1  LICENSEE shall inform M.I.T. promptly in writing of any alleged 
infringement of the PATENT RIGHTS by a third party and of any available evidence
thereof.

     7.2  M.I.T. shall have the right, but shall not be obligated, to prosecute 
at its own expense all infringements of the PATENT RIGHTS and, in furtherance of
such right, LICENSEE hereby agrees that M.I.T. may include LICENSEE as a party 
plaintiff in any such suit, without expense to LICENSEE. The total cost of any 
such infringement action commenced or defended solely by M.I.T. shall be borne 
by M.I.T., and M.I.T. shall keep any recovery or damages for past infringement 
derived therefrom.

     7.3  If within six (6) months after having been notified of an alleged
infringement, M.I.T. shall have been unsuccessful in persuading the alleged
infringer to desist and shall not have brought and shall not be diligently
prosecuting an infringement action, or if M.I.T. shall notify LICENSEE at any
time prior thereto of its intention not to bring suit against any alleged
infringer in the TERRITORY for the FIELD OF USE, then, and in those events only,
LICENSEE shall have the right, but shall not be obligated, to prosecute at its
own expense any infringement of the PATENT RIGHTS in the TERRITORY for the FIELD
OF USE, and LICENSEE may, for such purposes, use the name of M.I.T. as party
plaintiff. No settlement, consent judgment or other voluntary final disposition
of the suit may be entered into without the consent of M.I.T., which consent
shall not unreasonably be withheld. LICENSEE shall indemnify M.I.T. against any
order for costs that may be made against M.I.T. in such proceedings.

     7.4  In the event that LICENSEE shall undertake the enforcement and/or 
defense of the PATENT RIGHTS by litigation, LICENSEE may withhold up to fifty 
percent (50%) of the payments otherwise thereafter due M.I.T. under Article 4 
hereunder and apply the same toward reimbursement of up to half of LICENSEE's 
expenses, including reasonable attorneys' fees, in connection therewith. Any 
recovery of damages by LICENSEE for each such suit shall be applied

<PAGE>
 
first in satisfaction of any unreimbursed expenses and legal fees of LICENSEE 
relating to such suit, and next toward reimbursement of M.I.T. for any payments
under Article 4 past due or withheld and applied pursuant to this Article 7. The
balance remaining from any such recovery shall be between LICENSEE and M.I.T. in
the proportion of *************************************************************
*****.

     7.5  In the event that a declaratory judgment action alleging invalidity or
noninfringement of any of the PATENT RIGHTS shall be brought against LICENSEE, 
M.I.T., at its option, shall have the right, within thirty (30) days after 
commencement of such action, to intervene and take over the sole defense of the 
action at its own expense.

     7.6  In any infringement suit as either party may institute to enforce the 
PATENT RIGHTS pursuant to this Agreement, the other party hereto shall, at the 
request and expense of the party initiating such suit, cooperate in all respects
and, to the extent possible, have its employees testify when requested and make 
available relevant  records, papers, information, samples, specimens, and the 
like.

     7.7  LICENSEE, during any period that this Agreement remains exclusive, 
shall have the sole right in accordance with the terms and conditions herein to 
sublicense any alleged infringer in the TERRITORY for the FIELD OF USE for 
future use of the PATENT RIGHTS. Any fees as part of such a sublicense shall be 
treated per Article 4.

                             8 - PRODUCT LIABILITY
                             ---------------------

     8.1  LICENSEE shall at all times during the term of this Agreement and 
thereafter, indemnify, defend and hold M.I.T., its trustees, directors, 
officers, employees and affiliates, harmless against all claims, proceedings, 
demands and liabilities of any kind whatsoever, including legal expenses and 
reasonable attorneys' fees, arising out of the death of or injury to any person 
or persons or out of any damage to property, resulting from the production, 
manufacture, sale, use, lease, consumption or advertisement of the LICENSED 
PRODUCT(s) and/or LICENSED PROCESS(es) or arising from any obligation of 
LICENSEE hereunder.

     8.2  LICENSEE shall obtain and carry in full force and effect commercial, 
general liability insurance which shall protect LICENSEE and M.I.T. with respect
to events covered by Paragraph 8.1 above. Such insurance shall be written by a 
reputable insurance company authorized to do business in the Commonwealth of 
Massachusetts, shall list M.I.T. as an additional named insured thereunder, 
shall be endorsed to include product liability coverage and shall require thirty
(30) days written notice to be given to M.I.T. prior to any cancellation or
material change thereof. The limits of such insurance shall not be less than One
Million Dollars ($1,000,000) per occurrence with an aggregate of Three Million
Dollars ($3,000,000) for personal injury or death, and One Million Dollars
($1,000,000) per occurrence with an aggregate of Three Million Dollars
($3,000,000) for



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission

<PAGE>
 
property damage. LICENSEE shall provide M.I.T. with Certificates of Insurance 
evidencing the same.

     8.3 EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN THIS AGREEMENT, M.I.T., ITS
TRUSTEES, DIRECTORS, OFFICERS, EMPLOYEES, AND AFFILIATES MAKE NO REPRESENTATIONS
AND EXTEND NO WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, INCLUDING BUT
NOT LIMITED TO WARRANTIES OF MERCANTABILITY, FITNESS FOR A PARTICULAR PURPOSE,
VALIDITY OR PATENT RIGHTS CLAIMS, ISSUED OR PENDING, AND THE ABSENCE OF LATENT
OR OTHER DEFECTS, WHETHER OR NOT DISCOVERABLE. NOTHING IN THIS AGREEMENT SHALL
BE CONSTRUED AS A REPRESENTATION MADE OR WARRANTY GIVEN BY M.I.T. THAT THE
PRACTICE BY LICENSEE OF THE LICENSE GRANTED HEREUNDER SHALL NOT INFRINGE THE
PATENT RIGHTS OF ANY THIRD PARTY. IN NO EVENT SHALL M.I.T., ITS TRUSTEES,
DIRECTORS, OFFICERS, EMPLOYEES AND AFFILIATES BE LIABLE FOR INCIDENTAL OR
CONSEQUENTIAL DAMAGES OF ANY KIND, INCLUDING ECONOMIC DAMAGE OR INJURY TO
PROPERTY AND LOST PROFITS, REGARDLESS OF WHETHER M.I.T. SHALL BE ADVISED, SHALL
HAVE OTHER REASON TO KNOW, OR IN FACT SHALL KNOW OF THE POSSIBILITY OF THE
FOREGOING.

                              9 - EXPORT CONTROLS
                              -------------------

     LICENSEE acknowledges that it is subject to United States laws and 
regulations controlling the export of technical data, computer software, 
laboratory prototypes and other commodities (including the Arms Export Control 
Act, as amended and the United States Department of Commerce Export 
Administration Regulations). The transfer of such items may require a license 
form the cognizant agency of the United States Government and/or written 
assurances by LICENSEE that LICENSEE shall not export data or commodities to 
certain foreign countries without prior approval of such agency. M.I.T. neither 
represents that a license shall not be required not that, if required, it shall 
be issued.

                             10 - NON-USE OF NAMES
                             ---------------------

     LICENSEE shall not use the names or trademarks of the Massachusetts 
Institute of Technology or Lincoln Laboratory, nor any adaptation thereof, nor 
the names of any of their employees, in any advertising, promotional or sales 
literature without prior written consent obtained from M.I.T., or said employee,
in each case, except that LICENSEE may state that it is licensed by M.I.T. under
one or more of the patents and/or applications comprising the PATENT RIGHTS.
<PAGE>
 
                                11 - ASSIGNMENT
                                ---------------

     This Agreement is not assignable and any attempt to do so shall be void.

                            12 - DISPUTE RESOLUTION
                            -----------------------

     12.1 Except for the right of either party to apply to a court of competent 
jurisdiction for a temporary restraining order, a preliminary injunction, or
other equitable relief to preserve the status quo or prevent irreparable harm,
any and all claims, disputes or controversies arising under, out of, or in
connection with the Agreement, including any dispute relating to patent validity
or infringement, which the parties shall be unable to resolve within sixty (60)
days shall be mediated in good faith. The party raising such dispute shall
promptly advise the other party of such claim, dispute or controversy in a
writing which describes in reasonable detail the nature of such dispute. By not
later than five (5) business days after the recipient has received such notice
of dispute, each party shall have selected for itself a representative who shall
have the authority to bind such party, and shall additionally have advised the
other party in writing of the name and title of such representative. By not
later than ten (10) business days after the date of such notice of dispute, the
party against whom the dispute shall be raised shall select a mediation firm in
the Boston area and such representatives shall schedule a date with such firm
for a mediation hearing. The parties shall enter into good faith mediation and
shall share the costs equally. If the representatives of the parties have not
been able to resolve the dispute within fifteen (15) business days after such
mediation hearing, then any and all claims, disputes or controversies arising
under, out of, or in connection with this Agreement, including any dispute
relating to patent validity or infringement, shall be resolved by final and
binding arbitration in Boston, Massachusetts under the rules of the American
Arbitration Association, or the Patent Arbitration Rules if applicable, then
obtaining. The arbitrators shall have no power to add to, subtract from or
modify any of the terms or conditions of this Agreement, nor to award punitive
damages. Any award rendered in such arbitration may be enforced by either party
in either the courts of the Commonwealth of Massachusetts or in the United
States District Court for the District of Massachusetts, to whose jurisdiction
for such purposes M.I.T. and LICENSEE each hereby irrevocably consents and
submits.

     12.2 Notwithstanding the foregoing, nothing in this Article shall be 
construed to waive any rights or timely performance of any obligations existing 
under this Agreement.

                               13 - TERMINATION
                               ----------------

     13.1 If LICENSEE shall cease to carry on its business, this Agreement shall
terminate upon notice by M.I.T..

     13.2 Should LICENSEE fail to make any payment whatsoever due and payable to
M.I.T. hereunder, M.I.T. shall have the right to terminate this Agreement 
effective on thirty (30) days'
<PAGE>
 
notice, unless LICENSEE shall make all such payments to M.I.T. within said 
thirty (30) day period. Upon the expiration of the thirty (30) day period, if 
LICENSEE shall not have made all such payments to M.I.T., the rights, privileges
and license granted hereunder shall automatically terminate.

     13.3 Upon any material breach or default of this Agreement by LICENSEE 
(including, but not limited to, breach or default under Paragraph 3.3), other 
than those occurrences set out in Paragraphs 13.1 and 13.2 hereinabove, which 
shall always take precedence in that order over any material breach or default 
referred to in this Paragraph 13.3, M.I.T. shall have the right to terminate 
this Agreement and the rights, privileges and license granted hereunder 
effective on ninety (90) days' notice to LICENSEE. Such termination shall become
automatically effective unless LICENSEE shall have cured any such material 
breach or default prior to the expiration of the ninety (90) day period.

     13.4 LICENSEE shall have the right to terminate this Agreement at any time 
on six (6) months' notice to M.I.T., and upon payment of all amounts due M.I.T. 
through the effective date of the termination.

     13.5 Upon termination of this Agreement for any reason, nothing herein 
shall be construed to release either party from any obligation that matured 
prior to the effective date of such termination; and Articles 1, 8, 9, 10, 12,
13.5, 13.6, and 15 shall survive any such termination. LICENSEE and any
sublicensee thereof may, however, after the effective date of such termination,
sell all LICENSED PRODUCTS, and complete LICENSED PRODUCTS in the process of
manufacture at the time of such termination and sell the same, provided that
LICENSEE shall make the payments to M.I.T. as required by Article 4 of this
Agreement and shall submit the reports required by Article 5 hereof.

     13.6 Upon termination of this Agreement for any reason, any sublicensee not
then in default shall have the right to seek a license from M.I.T. M.I.T. agrees
to negotiate such licenses in good faith under reasonable terms and conditions.


                14 - PAYMENTS NOTICES AND OTHER COMMUNICATIONS
                ----------------------------------------------

     Any payments, notice or other communication pursuant to this Agreement 
shall be sufficiently made or given on the date of mailing if sent to such party
by certified first class mail, return receipt requested, postage prepaid, 
addressed to it at its address below or as it shall designate by written notice 
given to the other party:
<PAGE>
 
          In the case of M.I.T.:

          Director
          Technology Licensing Office
          Massachusetts Institute of Technology
          77 Massachusetts Avenue, Room E32-300
          Cambridge, Massachusetts 02139

          In the case of LICENSEE:

          (title)   President & CEO
          (company) Cubist Pharmacenticals, Inc.
          (address) 24 Emily Street
                    Cambridge, MA 02139

                         15 - MISCELLANEOUS PROVISIONS
                         -----------------------------

     15.1 All disputes arising out of or related to this Agreement, or the 
performance, enforcement, breach or termination hereof, and any remedies 
relating thereto, shall be construed, governed, interpreted and applied in 
accordance with the laws of the Commonwealth of Massachusetts, U.S.A., except 
that questions affecting the construction and effect of any patent shall be 
determined by the law of the country in which the patent shall have been 
granted.

     15.2 The parties hereto acknowledge that this Agreement sets forth the 
entire Agreement and understanding of the parties hereto as to the subject
matter thereof, and shall not be subject to any change or modification except by
the execution of a written instrument signed by the parties.

     15.3 The provisions of this Agreement are severable, and in the event that 
any provisions of this Agreement shall be determined to be invalid or 
unenforceable under any controlling body of the law, such invalidity or 
unenforceability shall not in any way affect the validity or enforceability of 
the remaining provisions hereof.

     15.4 LICENSEE agrees to mark the LICENSED PRODUCTS sold in the United 
States with all applicable United States patent numbers. All LICENSED PRODUCTS 
shipped to or sold in other countries shall be marked in such a manner as to 
conform with the patent laws and practice of the country of manufacture or sale.
<PAGE>
 
     15.6  The failure of either party to assert a right hereunder or to 
insist upon compliance with any term or condition of this Agreement shall not 
constitute a waiver of that right or excuse a similar subsequent failure to 
perform any such term or condition by the other party.

     IN WITNESS WHEREOF, the parties have duly executed this Agreement the day 
and year set forth below.

MASSACHUSETTS INSTITUTE OF                   CUBIST PHARMACEUTICAL, INC.
TECHNOLOGY

By   /s/ Lita Nelsen                         By    /s/ Scott M. Rocklage
  -----------------------------------------    ---------------------------------

Name     Lita L. Nelsen                      Name      Scott M. Rocklage
    ---------------------------------------      -------------------------------

Title DIRECTOR, TECHNOLOGY LICENSING OFFICE  Title  President & CEO
     --------------------------------------       ------------------------------

Date   21 July 1994                          Date   21 July 1994
     --------------------------------------       ------------------------------
<PAGE>
 
                                  APPENDIX A

                      PATENT RIGHTS on the EFFECTIVE DATE

UNITED STATES PATENT RIGHTS

M.I.T. Case No. 6484
                ----
Title "Process for Creating Molecular Diversity"
U.S.S.N. 180,215 or U.S.P.N.
By Julius Rebek, Jr., Thomas Carell and Edward Wintner
Filed on 1/12/94

FOREIGN PATENT RIGHTS
<PAGE>
 
                                  APPENDIX B

                         DESIGNATED FOREIGN COUNTRIES

Foreign countries in which PATENT RIGHTS shall be filed, prosecuted and 
maintained in accordance with Article 6:

[To Be Discussed]

<PAGE>
 
                                    [SEAL]

                           [LETTERHEAD APPEARS HERE]

August 31, 1994



Dr. Scott Rocklage
President and Chief Executive Officer
Cubist Pharmaceuticals, Inc.
24 Emily Street
Cambridge, MA 02139

Ref:   MIT Case No. 6484
       "Process for Creating Molecular Diversity and Novel Protease Inhibitors 
       Produced Thereby", By Julius Rebek, Jr. Thomas Carell, Edward A. Wintner
       Continuation-in-Part filed July 28, 1994

Dear Scott:

Enclosed is a copy of the continuation-in-part patent application recently filed
on this case. It was our intent to include this patent in the license granted to
you effective July 21, 1994.

Please acknowledge below that you wish to have this application included in the
PATENT RIGHTS of the license and return one copy to me.

Sincerely,

/s/ Lita Nelsen

Lita Nelsen
Director

Accepted for:

CUBIST PHARMACEUTICALS CORP.

By  /s/ Scott M. Rocklage
    ------------------------------
Title   PRESIDENT & CEO
        --------------------------
Date    9/6/94
        --------------------------

LLN/vc
Cubist 6484

<PAGE>
 
                                                                    EXHIBIT 10.2
                            Confidential Treatment 
                                                               .  September 1989


- --------------------------------------------------------------------------------

                               LICENSE AGREEMENT

- --------------------------------------------------------------------------------

Effective as of   4-1-94   THE BOARD OF TRUSTEES OF THE LELAND STANFORD JUNIOR 

UNIVERSITY, a body having corporate powers under the laws of the State of 

California (STANFORD), and   CUBIST PHARMACEUTICALS, INC.   a   DELAWARE   

corporation having a principal place of business at   24 EMILY STREET,

CAMBRIDGE, MA 02139   (LICENSEE) agree as follows:



                                 1. BACKGROUND

  1.1-In the course of fundamental research programs at the University of 
California and STANFORD (Universities), inventions were conceived jointly which 
relate to engineering biologically functional replicons possessing desired 
genetic properties of parent DNA molecules. These research programs were 
supported by the National Science Foundation, the American Cancer Society, and 
the National Institutes of Health of the Department of Health, Education and 
Welfare, now Health and Human Services (HHS). These agencies and the 
Universities agreed that the intellectual property rights resulting from these 
inventions (and licensed through this Agreement) would be administered pursuant 
and subject to the terms of STANFORD's Institutional Patent Agreement (IPA) with
HHS.

  1.2-The Universities have agreed that Stanford will manage the securing of 
patent rights and licensing in the public interest, and that any net income 
arising therefrom will be shared between the Universities, and designated to be 
used for educational and research purposes.

  1.3-By assignment of the inventions from the inventors, STANFORD is the owner 
of certain U.S. Patent rights and desires to grant licenses under those rights 
to licensees for development of products and processes for public use and 
benefit.

  1.4-LICENSEE desires to develop processes and methods and marketable products 
for public use and benefit by using Licensed Patent Rights, and it will follow 
good safety practices in such development work.


                                2. DEFINITIONS

  2.1-Licensed Patent Rights means U.S. Patent No. 4,237,224, issued December 2,
1980, U.S. Patent No. 4,468,464, issued August 28, 1984, and U.S. Patent No. 
4,740,470, issued April 26, 1988 and any reissues or extensions thereof.

  2.2-Ultimate Consumer means that person or entity whose use of the product 
results in its destruction or loss of activity and/or loss of value.

  2.3-Licensed Product(s) means materials (including organisms) which, in the 
course of manufacture, use, or sale would, in the absence of this license, 
infringe one or more claims of Licensed Patent Rights which have not been held 
invalid by a court from which no appeal may be taken.


                                       1



<PAGE>
 
Four categories of Licensed Products are designated:
  End Products (Paragraph 2.4)
  Basic Genetic Products (Paragraph 2.5)
  Process Improvement Products (Paragraph 2.6)
  Bulk Products (Paragraph 2.7)

  2.4-- End Products means marketable goods having at least one component coming
within LicenSed Products, or produced by a Licensed Product, which goods are 
sold in a form for utilization by the Ultimate Consumer, and are not intended or
marketed for further formulation, processing, or chemical transformation, 
illustrative End Products include:
        (a)  health care products, sold for patient care and use or dispensation
             by medical professionals (for example, dosage forms of hormones,
             vaccines, and biosynthesized drugs;films, fibers or dressings: and
             reagents or devices used for diagnostic purposes, incorporating
             biochemical agents such as antibodies, enzymes, specific binding
             proteins or polysaccharides);
        (b)  products sold in a form ready for application to seeds, for
             addition to feed or crop treating agents, for administration to
             animals or for treatment of cells being cultured in order to
             improve agriculture, animal production, forestry or landscaping
             (such as fertilizers, vaccines, and nitrogen fixing or pesticidal
             microorganisms);
        (c)  microorganisms and/or their products which are suitable for use as
             animal or human food, for degrading substances in an environment,
             or for increasing the production of desired substances (such as
             concentrating minerals, generating gas or useful compost from low
             value substrates):
        (d)  reagents for research, such as enzymes or antibodies.

  2.5--Basic Genetic Products means materials having at least one component 
coming within Licensed Products which are sold or used primarily for further 
processing or genetic manipulation and/or are neither End Products, Process 
Improvement Products or Bulk Products.  Illustrative Basic Genetic Products 
include plasmids, transformants, and nucleic acid segments such as expression 
regulators and structural gene sequences, Also, Basic Genetic Products include 
services using Licensed Products and which services are provided by LICENSEE to 
customers on a contract basis.

  2.6--Process Improvement Products means materials having at least one 
component coming within Licensed Products, which are developed by or for the 
LICENSEE, as opposed to being purchased by the LICENSEE, and are used by the  
LICENSEE in its manufacturing processes to enhance production efficiency and 
where  the resulting product is essentially identical to a product manufactured 
by the previous process, illustrative Process Improvement Products include 
microorganisms for production of chemical intermediates, amino acids, or 
pharmaceuticals; enzymes for chemical manufacturing; antibodies for separation 
processes; and nitrogen-fixing microorganisms used by an agricultural company to
reduce fertilizer consumption.

  2.7--Bulk Products means materials having at least one component coming within
Licensed Products, or produced by a Licensed Product, which material is intended
for further formulation, processing or chemical transformation by a 
manufacturer, formulator or the like (as distinguished from a distributor, 
retailer or Ultimate Consumer). Illustrative Bulk Products include an antibody 
or a hormone sold to a pharmaceutical company, a dipeptide sold to a beverage 
company to be used as a sweetener, an amino acid sold to a health care company, 
and a chemical intermediate sold to a chemical company for conversion into 
functional chemicals.

  2.8--Net Sales means the gross sales, royalties or fees received by Licensee, 
whether invoiced or not, less: returns and allowances actually granted; packing,
insurance, freight out, taxes or excise duties imposed on the transaction (if 
separately invoiced); wholesaler discounts and cash discounts.

2.9--First Commercial Sale means the initial transfer by LICENSEE of Licensed 
Products in exchange for cash or some equivalent to which value can be assigned 
for the purpose of determining Net Sales.

                                       2
<PAGE>
 
        2.10-"LICENSEE" is understood to include all of its Affiliates.  An 
Affiliate of LICENSEE shall mean any corporation or other business entity 
controlled by controlling, or under common control with LICENSEE.  For this 
purpose, "control" means direct or indirect beneficial ownership of at least 
fifty percent (50%) of the voting stock, or a least fifty percent (50%) interest
in the income of such corporation or other business.


                                   3. GRANT

        3.1-STANFORD grants to LICENSEE a non-exclusive, non-transferable right 
and license to make, have made, use and sell Licensed Products under Licensed 
Patent Rights.


              4. COMPLIANCE WITH LAWS, REGULATIONS AND STANDARDS

        4.1-LICENSEE agrees to comply with all governmental laws and regulations
applicable to the use, production and/or sale of Licensed Products.

        4.2-With respect to operations by the LICENSEE in the United States, it 
territories and possessions, LICENSEE specifically expresses  its intent to 
comply with the physical and biological containment standards set forth in the 
NIH Guidelines for Research involving Recombinant DNA Molecules, dated 21 
November 1980, or any subsequent amended version of U.S. Government guidelines 
or regulation pertaining to such activities in effect during the term of this 
Agreement.  LICENSEE further agrees to cooperate with government agency(ies) 
authorized to monitor compliance with such containment standards.


                              5. GOVERNMENT TERMS

        5.1-This Agreement is subject to the terms and conditions of the HHS IPA
with STANFORD dated April 5, 1972.


                                 6. ROYALTIES

        6.1-In consideration of the rights granted herein.  LICENSEE shall pay 
to STANFORD upon execution of this agreement ******.  Thereafter, LICENSEE shall
pay a minimum annual advance on earned royalties of ******* on or before the 
first day of February for each calendar year following execution of this 
agreement.  Said payments are nonrefundable except that they can be credited 
against earned royalties to the extent provided in paragraph 6.3.

        6.2-All sales or use of Licensed Products by LICENSEE, excepting sales 
under paragraph 10.1 to an Affiliate or another license of STANFORD or sales to 
the United States Government, shall be subject to royalty payments as provided 
in paragraphs 6.3 to 6.7 inclusive.

        6.3-Earned royalty payments due under Article 8 in excess of the annual 
minimum ******* may be reduced up to 50% in any one year by a credit.  This 
credit equal to the unreimbursed cumulative excess of the advance royalties paid
in accordance with paragraph 6.1 over the total of the earned royalties due 
under paragraphs 6.4 to 6.6 inclusive.  This reduction is earned royalty 
payments may continue so long as is necessary to fully amortize the credit.

        6.4-LICENSEE shall pay earned royalties for use of Licensed Patent 
Rights for production and sale of End Products based on the total royalty 
bearing Ne Sales of End Products by LICENSEE.  The earned royalty rate for End 
Products sold in the U.S. is ** in each calendar year.

6.5-LICENSEE shall pay earned royalties for use of Licensed Patent Rights to 
produce in the United States End Products and Bulk Products for sale outside of 
the United States of **** of Net Sales of End Products and ** of Net Sales of 
Bulk Products in each calendar year.


                                       3



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
  6.6-LICENSEE also shall pay earned royalties for use of Licensed Patent Rights
for production and sale of Licensed Products that are not End Products as
follows:

     6.6.1-The earned royalty rate for Basic Genetic Products sold in the U.S.
shall be **% of Net Sales.

     6.6.2-The earned royalty rate for Bulk Products sold in the U.S. is *% in
each calendar year.

     6.6.3-The earned royalty rate for Process Improvement Products shall be **%
of cost savings and economic benefits enjoyed by LICENSEE in each calendar year.

     6.6.4-If LICENSEE can demonstrated that the royalty payments for a product
falling under Basic Genetic Products (paragraph 6.6.1) Bulk Products (paragraph
6.6.2) or Process Improvement Products (paragraph 6.6.3) are greater than the
royalties that would result if calculated on the End Product (for sales in the
U.S. and other territories) made from or with such product, it may request
negotiation of a lower royalty comparable to the End Product royalty. Such
negotiation will be initiated by notice in writing from LICENSEE to STANFORD
giving the nature of the product(s) to be marketed by LICENSEE and expected use
of the product(s).

  6.7-If the parties cannot agree after negotiation upon equitable royalty terms
for the use of Licensed Patent Rights under subparagraph 6.6.4, then either
party may submit the matter for decision by arbitration in accordance with
paragraph 14.4. Fees for arbitration shall be borne by the LICENSEE, but may be
credited per paragraph 8.3 against royalties payable by LICENSEE under the
agreement established by means of the arbitration, until such arbitration fees
are fully recovered.

     6.7.1-In arriving at a decision, the negotiators and arbitrator(s) shall
consider such factors as the size of the potential market for the Licensed
Product(s) involved, the anticipated profit margin, the royalty rates for End
Products, the royalty that would be paid on the End Products most likely to be
prepared for the Ultimate Consumer from the Licensed Products(s) in question,
and prevailing royalty rates in the industry to which the Licensed Products(s)
pertain.


                             7. MORE FAVORED TERMS

  7.1-STANFORD intends that the terms of al licenses under Licensed Patent
Rights are to be essentially similar to the terms of this license. STANFORD will
advise LICENSEE as to those terms which are different in such other license
agreements, unless said terms are consequent to the operation of any provision
of paragraphs 6.6.4, 6.7, and 6.7.1, whereupon LICENSEE may determine whether
such terms are more favorable than those granted herein. LICENSEE shall, at its
election, be entitled upon written notice to STANFORD to have this Agreement
amended to substitute all terms of such more favorable license for all terms of
this Agreement as of the date upon which such more favorable license shall have
become effective. Such amendment shall, as to royalty, apply only to prospective
royalties.

  7.2-In the event LICENSEE chooses to exercise its option under paragraph 76.1,
LICENSEE agrees that it shall also accept and be bound by the same terms and
conditions for the benefit of STANFORD as those which are a part of or shall
accompany such other license granted by STANFORD to a third party. LICENSEE
further agrees that in determining whether the royalty rate for a particular
product or process accorded the third party licensee is more favorable, STANFORD
may assign a reasonable value to any patent rights or other consideration it has
or will receive in return for the grant of such other license.

  7.3-STANFORD has entered into prior license agreements for Licensed Patent
Rights. This Article 7 does not apply with respect to these prior license
agreements.


                           8. PAYMENTS AND REPORTS 

  8.1-LICENSEE agrees to notify STANFORD promptly, in writing, of the date of
the First Commercial Sale of a Licensed Product and date of first transaction
under paragraph 10.1.


                                       4



                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
     8.2--Beginning with date of First Commercial Sale, royalties from LICENSEE 
hereunder (less the credits allowed by paragraphs 6.3 and 6.7 and less the 
minimum annual royalty paid in advance for that calendar year) shall be paid to 
STANFORD within ninety (90) days after the close of each subsequent calendar 
quarter. 

     8.3--Total credits allowable by operation of paragraphs 6.3 and 6.7 shall 
in no case exceed 50% of the excess of current earned royalties over the minimum
royalty due in any given year. Any amount so credited shall be credited only 
once against earned royalties payable hereunder.

     8.4--LICENSEE shall provide with each earned royalty payment of paragraph 
8.2 a statement of Net Sales and the applicable royalties in accordance with 
Article 6 and a report of each transaction under paragraph 10.1. All such 
reports shall be held in confidence by STANFORD. Such statements and reports 
shall be submitted whether or not a payment in excess of the minimum is due.

     8.5--STANFORD is a nonprofit institution. Any taxes, fees, or other charges
imposed by governmental authorities upon payments due STANFORD shall be paid by 
LICENSEE. The amounts remitted shall be pursuant to payment terms of the 
agreement.

     8.6--To facilitate STANFORD's conformance with its Institutional Patent 
Agreement, LICENSEE agrees to make an annual report to STANFORD each March 1
covering its progress during the previous calendar year toward
commercialization. Such report may be general in nature and shall not include
company proprietary information.

     8.7--LICENSEE also agrees to make a written report to STANFORD within 
ninety (90) days after the date of termination of this License Agreement, 
stating in such report the royalty payable hereunder which was not previously 
reported to STANFORD. LICENSEE shall also continue to make annual reports 
pursuant to the provisions of this Article 8 covering Net Sales and the 
applicable royalties in accordance with Article 6 received for sale of Licensed 
Products after termination of this License Agreement, until such time as all 
such sales shall have terminated. Concurrent with the submittal of each 
post-termination report, LICENSEE shall pay STANFORD all applicable royalties.

                                  9. RECORDS

     9.1--LICENSEE shall keep complete, true and accurate books of account and 
records for the purpose of showing the derivation of all amounts payable to 
STANFORD under this License Agreement. Said books and records shall be kept at 
LICENSEE'S principal place of business for at least three (3) years following 
the end of the calendar year to which they pertain and shall be open at all 
reasonable times for inspection by a representative of STANFORD for the purpose 
of verifying LICENSEE's royalty statements or LICENSEE's compliance in other 
respects to this License Agreement. This representative is obliged to treat as 
confidential all relevant matters and should be acceptable to LICENSEE. LICENSEE
may specify that this representative be an independent Certified Public 
Accountant.

                   10. OTHER TRANSFERS OF LICENSED PRODUCTS

     10.1--It is anticipated that LICENSEE may supply Licensed Products to an 
Affiliate (as defined in paragraph 2.10) or to another licensee of STANFORD for 
further processing and/or sale by the Affiliate or other licensee under Licensed
Patent Rights. No earned royalty shall be payable by LICENSEE with respect to 
such Licensed Products, so long as the Affiliate or second licensee shall be 
obligated to pay STANFORD royalty under Licensed Patent Rights on its use or 
sales thereof. However, reports made by LICENSEE as provided in paragraph 8.4 
shall list each such transaction as a non-royalty bearing sale and identify such
Affiliate or other licensee.

     10.2--If an earned royalty payment has been made to STANFORD for a Licensed
Product used by LICENSEE to make another Licensed Product, that payment may be 
deducted by LICENSEE from the earned royalty payment for such resulting Licensed
Product.
<PAGE>
 
                           11. TERM AND TERMINATION

     11.1 - The term of this Agreement shall extend from the above effective 
date until expiration of the last to expire of Licensed Patent Rights.

     11.2 - Upon any breach of, or default under, this License Agreement by 
LICENSEE, STANFORD may terminate this License Agreement by ninety (90) days
written notice to LICENSEE. Said notice shall become effective at the end of
such period unless during said period LICENSEE shall cure such defect or
default.

     11.3 - LICENSEE shall have the right to terminate this Agreement at any 
time upon ninety (90) days written notice to STANFORD.


                              12.  ASSIGNABILITY

     12.1 - This Agreement shall not be assigned except (a) with the advance 
written consent of STANFORD, or (b) as part of a sale or transfer of 
substantially the entire business of LICENSEE relating to operations pursuant to
this license.


                   13.  NEGATION OF WARRANTIES AND INDEMNITY

     13.1 - Nothing in this Agreement shall be construed as:

         (a) a warranty or representation by STANFORD as to the validity or 
             scope of any Licensed Patent Rights; or

         (b) a warranty or representation that anything made, used, sold or 
             otherwise disposed of under any license granted in this Agreement
             is or will be free from infringement of patents of third parties; 
             or
         (c) an obligation to bring or prosecute actions or suits against third
             parties for infringement; or
         (d) conferring the right to use in advertising, publicity or otherwise
             any trademark, trade name, or names, or any contraction,
             abbreviation, simulation or adaptation thereof, of STANFORD;or
         (e) conferring by implication, estoppel or otherwise any license or 
             rights under any patents of STANFORD other than Licensed Patent 
             Rights, regardless of whether such patents are dominant or 
             subordinate to Licensed Patent Rights (however, STANFORD is not 
             aware of any STANFORD patent or application dominant to Licensed
             Patent Rights); or 
         (f) an obligation to furnish any know-how not provided in Licensed
             Patent Rights.

     13.2 - STANFORD makes no representations other than those specified in
Article 1. STANFORD MAKES NO EXPRESS OR IMPLIED WARRANTIES OF MERCHANTABILITY OR
FITNESS FOR A PARTICULAR PURPOSE.

     13.3 - LICENSEE shall defend, indemnify and hold STANFORD harmless from and
against all liability, demands, damages, expenses and losses for death, personal
injury, illness or property damage ("claims and damages") arising (a) out of the
use by LICENSEE of any method under Licensed Patent Rights, or (b) out of any
use, sale or other disposition of Licensed Products by LICENSEE or its
transferees. As used in this Section, "STANFORD" includes its trustees,
officers, agents and employees, and "LICENSEE" includes its Affiliates described
in paragraph 2.10. LICENSEE acknowledges that the technology licensed hereby is
experimental and agrees to take all reasonable precautions to prevent death,
personal injury, illness and property damage.


                                 14.  GENERAL

     14.1 - Neither party may waive or release any of its rights or interests in
this Agreement except in writing.  Failure to assert any right arising from this
Agreement shall not be deemed or construed to be a waiver of such right.

                                      6  


<PAGE>
 
     14.2 - This License Agreement constitutes the entire agreement between the 
parties relating to the subject matter thereof, and all prior negotiations, 
representations, agreements and understandings are merged into, extinguished by,
and completely expressed by it.

     14.3 - This Agreement and its effects are subject to and shall be construed
and enforced in accordance with the laws of the State of California.

     14.4 - Any dispute or controversy arising out of or relating to this
License Agreement, its construction or its actual or alleged breach, shall be
finally decided by arbitration conducted in San Francisco, California, by and in
accordance with the Licensing Agreement Arbitration Rules of the American
Arbitration Association. Judgment upon the award rendered may be entered in the
highest court or forum, state or federal, having jurisdiction; provided,
however, that the provisions of this Article 14 shall not apply to decision of
the validity of patent claims or to any dispute or controversy as to which any
treaty or law prohibits such arbitration.

     14.5 - All notices required or permitted to be given by the terms of this
Agreement shall be given by prepaid registered or certified mail properly
addressed to the other party at the address designated below or to such other
address as may be designated in writing by such other party and shall be
effective as of the date of the postmark of such mail notice.

         LICENSEE:



                           Attention:



         STANFORD:

                           Office of Technology Licensing
                           Stanford University
                           900 Welch Road, Suite 350
                           Palo Alto, CA 94304-1850
                           U.S.A.

                           Attention:  Director




     This Agreement is effective as of the date first given above.


     LICENSEE

     By  THOMAS SHEA
       -------------------------------------------------

     Title  DIRECTOR OF FINANCE
          ----------------------------------------------

     Date 5/11/94
         -----------------------------------------------

   
     THE BOARD OF TRUSTEES OF THE 
     LELAND STANFORD JUNIOR UNIVERSITY

     By  Katharine Ku
       --------------------------------------------------

     Title  DIRECTOR OF TECHNOLOGY LICENSING   
          -----------------------------------------------

     Date   May 18, 1994
         ------------------------------------------------

                                       7

<PAGE>
 
                                                                    EXHIBIT 10.6


                          CUBIST PHARMACEUTICALS, INC.

                  AMENDED AND RESTATED 1993 STOCK OPTION PLAN
            (adopted by the Board of Directors on June 11, 1996, but
             effective only upon the later of (i) the ratification
                and approval thereof by the stockholders of the
                 Company and (ii) the closing of the Company's
                            initial public offering)

     This Amended and Restated 1993 Stock Option Plan hereby further amends and
restates the Company's current Amended and Restated 1993 Stock Option Plan, as
heretofore amended, to read in its entirety as follows:

     1.   Definitions.  As used in this Amended and Restated 1993 Stock Option
          -----------                                                         
Plan of Cubist Pharmaceuticals, Inc., the following terms shall have the
following meanings:

     1.1. Awarded Grant Date means the date as of which an Awarded Option is
          ------- ----- ----                                                
granted, as determined under Section 7.1.

     1.2. Awarded Option means Options granted pursuant to Section 7 hereof.
          ------- ------                                                    

     1.3. Board means the Company's Board of Directors.
          -----                                        

     1.4  Change in Corporate Control means (1) the time of approval by the
          ------ -- --------- -------                                      
shareholders of the Company of (A) any consolidation or merger of the Company in
which the Company is not the continuing or surviving corporation or pursuant to
which Shares would be converted into cash, securities or other property, other
than a merger in which the holders of Stock immediately prior to the merger will
have the same proportionate ownership of common stock of the surviving
corporation immediately after the merger as before the merger, (B) any sale,
lease, exchange, or other transfer (in one transaction or a series of related
transactions) of all or substantially all the assets of the Company, or (C)
adoption of any plan or proposal for the liquidation or dissolution of the
Company, or (2) the date on which any "person" (as defined in Section 13(d) of
the Exchange Act), other than the Company or a Subsidiary or employee benefit
plan or trust maintained by the Company or any of its Subsidiaries shall become
(together with its "affiliates" and "associates," as defined in Rule 12b-2 under
the Exchange Act) the "beneficial owner" (as defined in Rule 13d-3 under the
Exchange Act), directly or indirectly, of more than 25% of the Stock outstanding
at the time, without the prior approval of the Board of Directors of the
Company.

     1.5. Code means the federal Internal Revenue Code of 1986, as amended.
          ----                                                             
<PAGE>
 
                                      -2-

     1.6.  Committee means a committee comprised of two or more Outside
           ---------                                                   
Directors, appointed by the Board of Directors, responsible for the
administration of the Plan, as provided in Section 5; provided, that the Board
                                                      --------                
of Directors itself may at any time, in its sole discretion, exercise any or all
functions and authority of the Committee.

     1.7.  Company means Cubist Pharmaceuticals, Inc., a Delaware corporation.
           -------                                                            

     1.8.  Exchange Act means the Securities Exchange Act of 1934, as amended.
           ------------                                                       

     1.9.  Eligible Director means a director of one or more of the Company and
           -----------------                                                   
its Subsidiaries who is not also an employee or officer of one or more of the
Company and its Subsidiaries.

     1.10. Fair Market Value means on any date (i) if the Stock is traded on a
           ---- ------ -----                                                  
stock exchange or on the Nasdaq National Market, the closing price on the date
in question or, if no trades were reported on such date, the closing price on
the most recent trading day preceding such date on which a trade occurred, and
(ii) if the Stock is not traded on a stock exchange or on the Nasdaq National
Market, the value of a Share on such date as determined by the Committee.

     1.11. Formula Grant means the grant of a Formula Option.
           -------------                                     

     1.12. Formula Grant Date shall have the meaning specified in Section 8.1
           ------------------                                                
hereof.

     1.13. Formula Options means Options granted pursuant to Section 8 hereof.
           ---------------                                                    

     1.14  Holder means, with respect to any Option, (i) the Optionee to whom
           ------                                                            
such Option shall have been granted under the Plan, or (ii) any transferee of
such Option to whom such Option shall have been transferred in accordance with
the provisions of Section 14.

     1.15. Incentive Option means an Awarded Option which by its terms is to be
           --------- ------                                                    
treated as an "incentive stock option" within the meaning of Section 422 of the
Code.

     1.16. Nonstatutory Option means any Option that is not an Incentive
           ------------ ------                                          
Option.

     1.17. Option means an Awarded Option or Formula Option granted under the
           ------                                                            
Plan to purchase Shares.
<PAGE>
 
                                      -3-

     1.18. Option Agreement means an agreement between the Company and an
           ------ ---------                                              
Optionee, setting forth the terms and conditions of an Option.

     1.19. Option Price means the price paid by an Optionee for a Share upon
           ------ -----                                                     
exercise of an Option.

     1.20. Optionee means a person eligible to receive an Option, as provided
           --------                                                          
in Section 6, to whom an Option shall have been granted under the Plan.

     1.21. Outside Director shall mean a member of the Board who is not an
           ------- --------                                               
officer, employee or consultant of the Company or any Subsidiary.

     1.22. Plan means this Amended and Restated 1993 Stock Option Plan of the
           ----                                                              
Company, as amended from time to time.

     1.23. Retirement means, with respect to any Optionee that is an employee
           ----------                                                        
or director of the Company, the voluntary retirement of such Optionee as an
employee and/or director, as the case may be, of the Company at any time after
age 65 or such earlier age as the Committee shall determine.

     1.24. Securities Act means the Securities Act of 1933, as amended.
           ---------- ---                                              
           
     1.25. Shares means shares of Stock.
           ------                       
           
     1.26. Stock means common stock, $.001 par value per share, of the Company.
           -----                                                               
           
     1.27. Subsidiary means any corporation which qualifies as a subsidiary of
           ----------                                                         
the Company under the definition of "subsidiary corporation" in Section 424(f)
of the Code.

     1.28. Ten Percent Owner means a person who owns, or is deemed within the
           --- ------- -----                                                 
meaning of Section 422(b)(6) of the Code to own, stock possessing more than 10%
of the total combined voting power of all classes of stock of the Company (or
its parent or Subsidiaries).  Whether a person is a Ten Percent Owner shall be
determined with respect to each Incentive Option based on the facts existing
immediately prior to the applicable grant date thereof.

     1.29. Vesting Year for any portion of any Incentive Option means the
           ------- ----                                                  
calendar year in which that portion of the Incentive Option first becomes
exercisable.

     2.    Purpose.  This Plan is intended to encourage ownership of Stock by
           -------                                                           
officers, employees and directors of and consultants to the Company and its
<PAGE>
 
                                      -4-

Subsidiaries and to provide additional incentives for them to promote the
success of the Company's business.  The Plan is intended to be an incentive
stock option plan within the meaning of Section 422 of the Code but not all
Options granted hereunder are required to be Incentive Options.

     3.    Term of the Plan.  Options may be granted hereunder at any time in
           ---- -- --- ----                       
the period commencing upon the effectiveness of the Plan pursuant to Section 21
and ending on May 6, 2003.

     4.    Stock Subject to the Plan.  Subject to the provisions of Section 
           ----- ------- -- --- ----               
15 of the Plan, at no time shall the number of Shares then outstanding which are
attributable to the exercise of Options granted under the Plan, plus the number
                                                                ----           
of Shares then issuable upon exercise of outstanding Options granted under the
Plan exceed 1,500,000 Shares, which aggregate number of Shares, automatically
and without further action, shall increase, on January 1, 1998, and each January
1 thereafter during the term of the Plan, by an additional number of Shares
equal to fifteen percent (15%) of the difference between (i) the total number of
Shares and Stock equivalents (other than Options) issued and outstanding as of
the close of business on December 31 of the immediately preceding year and (ii)
the total number of Shares and Stock equivalents (other than Options) issued and
outstanding as of the close of business on December 31 of the year prior to such
immediately preceding year.  Notwithstanding the foregoing, no more than an
aggregate of 3,000,000 Shares (subject to adjustment pursuant to the provisions
of Section 15 hereof) may be issued pursuant to the exercise of Incentive Stock
Options granted under the Plan.  Shares to be issued upon the exercise of
Options granted under the Plan may be either authorized but unissued Shares or
Shares held by the Company in its treasury.  If any Option expires or terminates
for any reason without having been exercised in full, the Shares not purchased
thereunder shall again be available for Options thereafter to be granted.

     5.    Administration.  The Plan shall be administered by the Committee.
           --------------                                                    
Subject to the provisions of the Plan, the Committee shall have complete
authority, in its discretion, to make or to select the manner of making the
following determinations with respect to each Awarded Option to be granted by
the Company:  (a) the officer, employee or consultant to receive such Awarded
Option; (b) whether the Awarded Option (if granted to an employee) will be an
Incentive Option or Nonstatutory Option; (c) the time of granting the Awarded
Option; (d) the number of Shares subject to the Awarded Option; (e) the Option
Price; (f) the option period; (g) the exercise date or dates or, if the Awarded
Option is immediately exercisable in full on its grant date, the vesting
schedule, if any, applicable to the Shares issuable upon the exercise of the
Awarded Option; (h) the effect of termination of employment, consulting or
association with the Company on the subsequent exercisability of the Awarded
Option; and (i) if the Awarded Option is a Nonstatutory  Option, whether such
Nonstatutory 
<PAGE>
 
                                      -5-

Option may be transferred by the Holder to a third party. Subject to the
provisions of the Plan, the Committee shall have complete authority, in its
discretion, to determine whether any Formula Option may be transferred by the
Holder to a third party. In making such determinations, the Committee may take
into account the nature of the services rendered by the respective officers,
employees and consultants, their present and potential contributions to the
success of the Company and its Subsidiaries, and such other factors as the
Committee in its discretion shall deem relevant. Subject to the provisions of
the Plan, the Committee shall also have complete authority to interpret the
Plan, to prescribe, amend and rescind rules and regulations relating to it, to
determine the terms and provisions of the respective Option Agreements (which
need not be identical), and to make all other determinations necessary or
advisable for the administration of the Plan. The Committee's determinations on
the matters referred to in this Section 5 shall be conclusive.

     6.   Eligibility.  An Awarded Option may be granted only to an employee
          -----------                
or officer of or consultant to one or more of the Company and its Subsidiaries,
provided that Incentive Options may be granted only to an employee (including an
- --------                                                                        
officer that is an employee) of the Company or one or more of its Subsidiaries.
Each Eligible Director shall receive Formula Options pursuant to Section 8
hereof.  Eligible Directors may not be granted Awarded Options in their
capacities as directors of the Company, but those Eligible Directors that are
also consultants to the Company may be granted Awarded Options in their
capacities as consultants.  Subject to adjustment pursuant to Section 15 hereof,
no person in any year may be granted Options with respect to more than 500,000
Shares.

     7.   Awarded Options.
          ------- -------

     7.1. Time of Granting Awarded Options.  The granting of an Awarded Option
          ---- -- -------- ------- -------                                    
shall take place at the time specified by the Committee.  Only if expressly so
provided by the Committee, shall the Awarded Grant Date be the date on which an
Option Agreement shall have been duly executed and delivered by the Company and
the Optionee.

     7.2. Option Price.  The Option Price under each Awarded Option shall be
          ------ -----                                                      
determined by the Committee but, in the case of any Incentive Option, shall be
not less than 100% of the Fair Market Value of Stock on the Awarded Grant Date,
or not less than 110% of the Fair Market Value of Stock on the Awarded Grant
Date if the Optionee is a Ten Percent Owner.  The Option Price under each
Nonstatutory Option shall not be so limited solely by reason of this Section
7.2.

     7.3. Awarded Option Period.  No Incentive Option may be exercised later
          ------- ------ ------                                             
than the tenth (10th) anniversary of the Awarded Grant Date but in any case not
later than the fifth (5th) anniversary of the Awarded Grant Date if the 
<PAGE>
 
                                      -6-

Optionee is a Ten Percent Owner. The option period under each Nonstatutory
Option shall not be so limited solely by reason of this Section 7.3.

     7.4. Vesting.  An Awarded Option may become exercisable in such
          -------                                                   
installments, cumulative or non-cumulative, as the Committee may determine.  In
the case of an Awarded Option not otherwise immediately exercisable in full, the
Committee may accelerate the exercisability of such Awarded Option in whole or
in part at any time, provided the acceleration of the exercisability of any
                     ---------                                             
Incentive Option would not cause the Awarded Option to fail to comply with the
provisions of Section 422 of the Code.

     7.5. Limit on Incentive Option Characterization.  No Incentive Option shall
          ----- -- --------- ------ ----------------                            
be considered an Incentive Option to the extent pursuant to its terms it would
permit the Optionee to purchase for the first time in any Vesting Year under
that Incentive Option more than the number of Shares calculated by dividing the
current limit by the Option Price.  The current limit for any Optionee for any
Vesting Year shall be $100,000 minus the aggregate Fair Market Value (determined
as of the respective Awarded Grant Dates) of the number of Shares available for
purchase for the first time in the Vesting Year under each other Incentive
Option granted to the Optionee under the Plan and each other incentive stock
option granted to the Optionee after December 31, 1986 under any other incentive
stock option plan of the Company (and any parent corporation and Subsidiaries).
Any Shares subject to an Incentive Option in excess of the foregoing limitation
shall be treated as if granted under a Nonstatutory Option with otherwise
identical terms.

     8.   Formula Options.
          ------- ------- 

     8.1. Directors Elected For First Time.  Subject to the Plan's effectiveness
          --------- ------- --- ----- ----                                      
as set forth in Section 21, each Eligible Director who is elected to the Board,
and was never before a member of the Board, and who is elected to the Board
during the term of the Plan (whether elected at an annual or special
stockholders' meeting or by action of the Board or written consent of
stockholders without a meeting), shall be granted, on the date of such meeting
or other appointment (as used in or with reference to this Section 8.1, a
"Formula Grant Date"), a Nonstatutory Option to purchase 7,000 Shares.  Grants
 ------- ----- ----                                                           
of Formula Options under this Section 8.1 occur automatically without any action
being required of the Optionee, the Committee, the Board of Directors, the
Company or any other person, entity or body.

     8.2. Annual Formula Grants.  Subject to the Plan's effectiveness as set
          ------ ------- ------                                             
forth in Section 21, on the date of each annual meeting of stockholders of the
Company commencing with the 1997 Annual Meeting of Stockholders of the Company,
each Eligible Director who continues to be a director of the Company on the
business day immediately following such annual meeting of stockholders 
<PAGE>
 
                                      -7-

shall be granted a Nonstatutory Option on such business day (also referred to as
a Formula Grant Date"), to purchase 700 Shares.  Grants of Formula Options under
  ------- ----- ---- 
this Section 8.2 occur automatically without any action being required of the
Optionee, the Committee, the Board of Directors, the Company or any other
person, entity or body.

     8.3. Certain Terms of Formula Options.  Each Formula Option granted to an
          ------- ----- -- ------- -------                                    
Optionee under this Section 8 shall have an exercise price equal to 100% of the
Fair Market Value of the Stock on the applicable Formula Grant Date.  No Formula
Option granted pursuant to this Section 8 is intended to qualify as an incentive
stock option within the meaning of Section 422 of the Code.  The Formula Grants
shall be evidenced by Option Agreements containing provisions that are in all
respects consistent with this Section 8.  All of such Option Agreements shall
contain identical terms and conditions, except as otherwise required or
permitted by this Section 8.

     8.4. Option Period.  The option period for any Formula Option granted
          ------ ------                                                   
pursuant to this Section 8 shall be ten years from the date of grant.

     8.5. Exercisability.  Each Formula Option granted to an Eligible Director
          --------------                                                      
pursuant to Section 8.1 hereof (a "Section 8.1 Formula Option") shall become
exercisable in twelve (12) equal installments, with the first installment
becoming exercisable on the last day of the first full fiscal quarter following
the Formula Grant Date applicable to such Section 8.1 Formula Option and an
additional installment becoming exercisable on the last day of each of the
eleven successive fiscal quarters following such first fiscal quarter; provided,
                                                                       -------- 
however, that if the Optionee with respect to such Section 8.1 Formula Option
- -------                                                                      
shall cease to be a director of the Company and each of its Subsidiaries, then,
notwithstanding anything in this Section 8.5 to the contrary and subject to
Sections 8.6 and 13 hereof, such Section 8.1 Formula Option shall thereafter be
exercisable only with respect to those of such installments for which such
Section 8.1 Formula Option is exercisable, pursuant to this Section 8.5, at the
time of such cessation.  Each Formula Option granted to an Eligible Director
pursuant to Section 8.2 hereof (a "Section 8.2 Formula Option") shall become
exercisable in four (4) equal installments, with the first installment becoming
exercisable on the last day of the first full fiscal quarter following the
Formula Grant Date applicable to such Section 8.2 Formula Option and an
additional installment becoming exercisable on the last day of each of the three
successive fiscal quarters following such first fiscal quarter; provided,
                                                                -------- 
however, that if the Optionee with respect to such Section 8.2 Formula Option
- -------                                                                      
shall cease to be a director of the Company and each of its Subsidiaries, then,
notwithstanding anything in this Section 8.5 to the contrary and subject to
Sections 8.6 and 13 hereof, such Section 8.2 Formula Option shall thereafter be
exercisable only with respect to those of such installments for which such
Section 8.2 Formula Option is exercisable, pursuant to this Section 8.5, at the
time of such cessation.
<PAGE>
 
                                      -8-

     8.6. Certain Modifications of Formula Options.  Notwithstanding anything in
          ----------------------------------------                              
this Section 8 or any applicable Option Agreement to the contrary, the Board or
any committee of two or more Outside Directors that are disinterested in the
matter may (i) accelerate the exercisability of any Formula Option in whole or
in part at any time or (ii) determine and alter at any time the effect that the
termination of any Optionee's position as a director of the Company shall have
on the exercisability of any Formula Option held by a Holder.

     9.   Exercise of Option.
          -------- -- ------ 

          (a)  An Option may be exercised only by giving written notice, in the
manner provided in Section 20 hereof, specifying the number of Shares as to
which the Option is being exercised, accompanied (except as otherwise provided
in paragraph (b) of this Section 9) by full payment for such Shares in the form
of a check or bank draft payable to the order of the Company or other Shares
with a current Fair Market Value equal to the Option Price of the Shares to be
purchased.  Receipt by the Company of such notice and payment shall constitute
the exercise of the Option or a part thereof.  Subject to the provisions of the
Plan (including, without limitation, Sections 10, 11 and 12) or any applicable
Option Agreement, within 30 days after receipt of such notice and payment, the
Company shall deliver or cause to be delivered to the Holder a certificate or
certificates for the number of Shares then being purchased by the Holder.  Such
Shares shall be fully paid and nonassessable.  If such Shares are not at that
time effectively registered under the Securities Act, the Holder shall include
with such notice a letter, in form and substance satisfactory to the Company,
confirming that such Shares are being purchased for the Holder's own account for
investment and not with a view to distribution.

          (b)  In lieu of payment by check, bank draft or other Shares
accompanying the written notice of exercise as described in paragraph (a) of
this Section 9, a Holder may, unless prohibited by applicable law, elect to
effect payment by including with the written notice referred to in paragraph (a)
of this Section 9 irrevocable instructions to deliver for sale to a registered
securities broker acceptable to the Company that number of Shares subject to the
Option being exercised sufficient, after brokerage commissions, to cover the
aggregate exercise price of such Option and, if the Holder further elects, the
withholding obligations of the Optionee and/or such Holder pursuant to Section
12 with respect to such exercise, together with irrevocable instructions to such
broker to sell such Shares and to remit directly to the Company such aggregate
exercise price and, if the Holder has so elected, the amount of such withholding
obligation.  The Company shall not be required to deliver to such securities
broker any stock certificate for such Shares until it has received from the
broker 
<PAGE>
 
                                      -9-

such exercise price and, if the Holder has so elected, the amount of such
withholding obligation.

          (c)  The right of the Holder to exercise an Option pursuant to any
provision of this Section 9, and the obligation of the Company to issue Shares
upon any exercise of an Option pursuant to this Section 9, is subject to
compliance with all of the other provisions of the Plan (including, without
limitation, Sections 10, 11 and 12) or any applicable Option Agreement.

     10.  Restrictions on Issue of Shares.
          ------------ -- ----- -- ------ 

          (a)  Notwithstanding any other provision of the Plan, if, at any time,
in the reasonable opinion of the Company the issuance of Shares covered by the
exercise of any Option may constitute a violation of law, then the Company may
delay such issuance and the delivery of a certificate for such Shares until (i)
approval shall have been obtained from such governmental agencies, other than
the Securities and Exchange Commission, as may be required under any applicable
law, rule, or regulation; and (ii) in the case where such issuance would
constitute a violation of a law administered by or a regulation of the
Securities and Exchange Commission, one of the following conditions shall have
been satisfied:

     (1)  the Shares with respect to which such Option has been exercised are at
the time of the issue of such Shares effectively registered under the Securities
Act; or

     (2)  a no-action letter in form and substance reasonably satisfactory to
the Company with respect to the issuance of such Shares shall have been obtained
by the Company from the Securities and Exchange Commission.

The Company shall make all reasonable efforts to bring about the occurrence of
said events.

          (b)  Each certificate representing Shares issued upon the exercise of
an Option will bear restrictive legends which may refer to this Plan.

     11.  Purchase for Investment; Subsequent Registration.
          -------- --- ----------  ---------- ------------ 

          (a)  Without limiting the generality of Section 10 hereof, if the
Shares to be issued upon exercise of an Option granted under the Plan have not
been effectively registered under the Securities Act, the Company shall be under
no obligation to issue any Shares covered by any Option unless the person who
exercises such Option, in whole or in part, shall give a written representation
to the Company which is satisfactory in form and substance to its counsel and
upon which the Company may reasonably rely, that he or she is acquiring the
Shares 
<PAGE>
 
                                     -10-

issued pursuant to such exercise of the Option as an investment and not
with a view to, or for sale in connection with, the distribution of any such
Shares.

          (b)  Each Share issued pursuant to the exercise of an Option granted
pursuant to this Plan may bear a reference to the investment representation made
in accordance with this Section 11 and to the fact that no registration
statement has been filed with the Securities and Exchange Commission in respect
to said Stock.

          (c)  If the Company shall deem it necessary or desirable to register
under the Securities Act or other applicable statutes any Shares with respect to
which an Option shall have been granted, or to qualify any such Shares for
exemption from the Securities Act or other applicable statutes, then the Company
shall take such action at its own expense.  The Company may require from each
Option holder, or each holder of Shares acquired pursuant to the Plan, such
information in writing for use in any registration statement, prospectus,
preliminary prospectus or offering circular as is reasonably necessary for such
purpose and may require reasonable indemnity to the Company and its officers and
directors from such holder against all losses, claims, damage and liabilities
arising from such use of the information so furnished and caused by any untrue
statement of any material fact therein or caused by the omission to state a
material fact required to be stated therein or necessary to make the statements
therein not misleading in the light of the circumstances under which they were
made.

     12.  Withholding; Notice of Disposition of Stock Prior to Expiration of
          -----------  ------ -- ----------- -- ----- ----- -- ---------- --
Specified Holding Period.
- --------- ------- ------ 

          (a)  Whenever Shares are to be issued in satisfaction of an Option
granted hereunder, the Company shall have the right to require the Optionee
and/or any subsequent Holder to remit to the Company an amount sufficient to
satisfy federal, state, local, employment or other tax withholding requirements
if and to the extent required by law (whether so required to secure for the
Company an otherwise available tax deduction or otherwise) prior to the delivery
of any certificate or certificates for such Shares.

          (b)  The Company may require as a condition to the issuance of Shares
covered by any Incentive Option that the party exercising such Option give a
written representation to the Company which is satisfactory in form and
substance to its counsel and upon which the Company may reasonably rely, that he
or she will report to the Company any disposition of such Shares prior to the
expiration of the holding periods specified by Section 422(a)(1) of the Code.
If and to the extent that the realization of income in such a disposition
imposes upon the Company federal, state, local or other withholding tax
requirements, or any such withholding is required to secure for the Company an
otherwise 
<PAGE>
 
                                     -11-

available tax deduction, the Company shall have the right to require that the
recipient remit to the Company an amount sufficient to satisfy those
requirements; and the Company may require as a condition to the issuance of
Shares covered by an Incentive Option that the party exercising such Incentive
Option give a satisfactory written representation promising to make such a
remittance.

          (c)  The Committee may, at or after grant, permit an Optionee and/or
subsequent Holder to satisfy any tax withholding requirements pertaining to the
exercise of an Option by delivery to the Company of Shares (including, without
limitation, Shares retained from the Option exercise that is creating the tax
obligation) having a value equal to the amount to be withheld.  The value of
Shares to be so delivered shall be based on the Committee's determination of the
Fair Market Value of a Share on the date the amount of tax to be withheld is to
be determined.

     13.  Termination of Association with the Company.  If an Optionee ceases to
          ----------- -- ----------- ---- --- -------                           
be an employee, director or consultant of the Company and its Subsidiaries for
any reason other than Retirement or death of such Optionee, any Option held by
such Optionee and/or any subsequent Holder may be exercised by such Optionee
and/or such subsequent Holder at any time within 90 days after the termination
of such relationship, but only to the extent exercisable at termination and in
no event after the applicable option period.  If an Optionee enters Retirement
or dies, any Option held by such Optionee and/or any subsequent Holder may be
exercised by such Optionee, such subsequent Holder and/or the executor or
administrator of such Optionee or such subsequent Holder at any time within the
shorter of the applicable option period or 12 months after the date of the
Optionee's Retirement or death, but only to the extent exercisable at the time
of such Optionee's Retirement or death.  Options which are not exercisable at
the time of termination of such relationship between the Company and the
Optionee or which are so exercisable but are not exercised within the time
periods described above shall terminate.  Notwithstanding the foregoing, in the
event that (i) the applicable Option Agreement with respect to an Option shall
contain specific provisions governing the effect that any such termination shall
have on the exercisability of such Option or (ii) the Board, the Committe or any
other committee of the Board composed of Outside Directors that are
disinterested on the matter, as appropriate, shall at any time adopt specific
provisions governing the effect that any such termination shall have on the
exercisability of such Option, then such provisions shall, to the extent that
they are inconsistent with the provisions of this Section 13, control and be
deemed to supersede the provisions of this Section 13. For purposes of this
Section 13, military or sick leave shall not be deemed a termination of
employment, provided that it does not exceed the longer of 90 days or the period
            --------                                                            
during which the absent Optionee's reemployment rights, if any, are guaranteed
by statute or by contract.
<PAGE>
 
                                     -12-

     14.  Transferability of Options.  Incentive Options shall not be
          --------------- -- -------                                 
transferable, otherwise than by will or the laws of descent and distribution,
and may be exercised during the life of the Optionee only by the Optionee.
Nonstatutory Options shall not be transferable; provided, however, that
                                                --------  -------      
Nonstatutory Options shall be transferable by will or the laws of descent and
distribution; and provided, further, that Nonstatutory Options may be
                  --------  -------                                  
transferred to a third party if and to the extent authorized and permitted by
the Compensation Committee.  In granting its authorization and permission to any
proposed transfer of a Nonstatutory Option to a third party, the Compensation
Committee may impose conditions or requirements that must be satisfied by the
transferor or the third party transferee prior to or in connection with such
transfer, including, without limitation, any conditions or requirements that may
be necessary or desirable, in the sole and absolute discretion of the Committee,
to ensure that such proposed transfer complies with applicable securities laws
or to prevent the Company, such transferor or such third party transferee from
violating or otherwise not be in compliance with applicable securities laws as a
result of such transfer.  For purposes of this Section 14, the term Nonstatutory
Option shall include an Option that was an Incentive Option at the time of
grant, but that has been subsequently been disqualified or otherwise lost its
status as an Incentive Option.  The restrictions on transferability set forth in
this Section 14 shall in no way preclude any Holder from effecting "cashless"
exercises of an Option pursuant to, and in accordance with, Section 9(b) hereof.

     15.  Adjustment of Number of Option Shares.  In the event of any stock
          ---------- -- ------ -- ------ ------                            
dividend payable in Stock or any split-up or contraction in the number of Shares
prior to the exercise in full of an Option, the number of Shares subject to the
Option and the price to be paid for each Share subject to the Option shall be
proportionately adjusted.  In the event of any reclassification or change of
outstanding Stock or in case of any consolidation or merger of the Company with
or into another company or in case of any sale or conveyance to another company
or entity of the property of the Company as a whole or substantially as a whole,
shares of stock or other securities equivalent in kind and value to those shares
a Holder would have received if he or she had held the full number of Shares
subject to the Option immediately prior to such reclassification, change,
consolidation, merger, sale or conveyance and had continued to hold those shares
(together with all other shares, stock and securities thereafter issued in
respect thereof) to the time of the exercise of the Option shall thereupon be
subject to the Option.  Upon dissolution or liquidation of the Company, the
Option shall terminate, but the Holder (if at the time the Optionee is in the
employ or retained as a consultant or serving as a director of the Company or
any of its Subsidiaries) shall have the right, immediately prior to such
dissolution or liquidation, to exercise the Option to the extent not theretofore
exercised.  No fraction of a share shall be purchasable or deliverable upon
exercise, but in the event that any adjustment hereunder of the number of 
<PAGE>
 
                                     -13-

Shares covered by the Option shall cause such number to include a fraction of a
Share, such number of Shares shall be adjusted to the nearest smaller whole
number of shares. In the event of changes in the outstanding Stock by reason of
any stock dividend, split-up, contraction, reclassification, or change of
outstanding Shares of the nature contemplated by this Section 15, the number of
Shares available for the purpose of the Plan as stated in Section 4 hereof shall
be correspondingly adjusted.

     16.  Change in Corporate Control.  Upon a Change in Corporate Control, each
          ------ -- --------- -------                                           
outstanding Option shall immediately become fully exercisable.

     17.  Reservation of Stock.  The Company shall at all times during the term
          ----------- --  ----                                                 
of the Plan and, without duplication, of any outstanding Options reserve or
otherwise keep available such number of Shares as will be sufficient to satisfy
the requirements of the Plan (if not then terminated) and such outstanding
Options and shall pay all fees and expenses necessarily incurred by the Company
in connection therewith.

     18.  Limitation of Rights in Stock; No Special Employment or Other Rights.
          ---------- -- ------ -- -----  -- ------- ---------- -- ----- ------  
A Holder shall not be deemed for any purpose to be a stockholder of the Company
with respect to any of the Shares covered by an Option, except to the extent
that the Option shall have been exercised with respect thereto and, in addition,
a certificate shall have been issued therefor and delivered to the Holder or his
agent.  Any Stock issued pursuant to the Option shall be subject to all
restrictions upon the transfer thereof which may be now or hereafter imposed by
the Certificate of Incorporation, and the By-laws of the Company, if any.
Nothing contained in the Plan or in any Option shall confer upon any Optionee
any right with respect to the continuation of his or her employment with, or
retention as a consultant, director or advisor to, the Company (or any
Subsidiary), or interfere in any way with the right of the Company (or any
Subsidiary), subject to the terms of any separate employment or consulting
agreement or provision of law or corporate articles or by-laws to the contrary,
at any time to terminate such employment, consulting, directorship or advisory
relationship or to increase or decrease the compensation of the Optionee from
the rate in existence at the time of the grant of an Option.

     19.  Termination and Amendment of the Plan.  The Board may at any time
          ----------- --- --------- -- --- ----                            
terminate the Plan or make such modifications of the Plan as it shall deem
advisable.  No termination or amendment of the Plan may, without the consent of
the Holder of any Option, adversely affect the rights of such Holder under such
Option.

     20.  Notices and Other Communications.  All notices and other
          ------- --- ----- --------------                        
communications required or permitted under the Plan shall be effective if in
writing and if delivered or sent by certified or registered mail, return receipt
<PAGE>
 
                                     -14-

requested (a) if to the Holder, at his or her residence address last filed with
the Company, and (b) if to the Company, at 24 Emily Street, Cambridge,
Massachusetts 02139, Attention: President or to such other persons or addresses
as the Holder or the Company may specify by a written notice to the other from
time to time.  Copies of all notices sent to any Holder that is not the Optionee
shall also be sent to the Optionee in the manner set forth in this Section 20.

     21.  Effectiveness.  This Amended and Restated 1993 Stock Option Plan was
          -------------                                                       
approved by the Board of Directors on June 11, 1996, but shall not become
effective until and unless the later of (i) the ratification and approval of
this Amended and Restated 1993 Stock Option Plan by the stockholders of the
Company and (ii) the consummation of the Company's proposed initial public
offering.  Prior to the effectiveness of this Amended and Restated 1993 Stock
Option Plan, the Company's existing Amended and Restated 1993 Stock Option Plan,
as amended from time to time prior to the effectiveness of this Amended and
Restated 1993 Stock Option Plan, shall remain in full force and effect.

<PAGE>
 
                                                                    EXHIBIT 10.7


                            Confidential Treatment
 
                       COLLABORATIVE RESEARCH AGREEMENT

     This COLLABORATIVE RESEARCH AGREEMENT is entered into as of December 15, 
     1995 by and between Pfizer Inc ("Pfizer"), a Delaware corporation, having
     an office at 235 East 42nd Street, New York, New York 10017 and its 
     Affiliates, and Cubist Pharmaceuticals, Inc. ("Cubist"), a Delaware 
     corporation, having an office at 24 Emily Street, Cambridge, MA 02139.

     WHEREAS, Cubist has expertise in the biochemistry and molecular biology 
     of tRNA synthetases from microorganism and human sources; and  

     WHEREAS, Cubist has the scientific capability and capacity to undertake the
     work described in the "Research Plan;" and

     WHEREAS, Pfizer has the capability to undertake development of agents for 
     treatment of infectious disease; and 

     WHEREAS, Pfizer possesses a library of compounds and is able to determine 
     the enzyme inhibitory capability of each compound versus Cubist's tRNA 
     synthetase targets in a "Primary Screening Program;" and 

     WHEREAS, Pfizer desires to compensate Cubist for access to Cubist
     Technology, its costs associated with preparing the tRNA synthetase targets
     and conducting a "Secondary Screening Program" and by paying Cubist 
     additional amounts based on achievement of certain milestones and on
     commercial sales;



                                       1


<PAGE>
 
                                       2

NOW, THEREFORE, the parties agree as follows:

1.   Definitions
     -----------
Whenever used in this Agreement, the terms defined in this Section 1 shall have 
the meanings specified.

     1.1  "Affiliate" means any corporation of other legal entity owning, 
           --------- 
directly or indirectly, fifty percent (50%) or more of the voting capital shares
or similar voting securities of Pfizer or Cubist; and corporation or other legal
entity fifty percent (50%) or more of the voting capital shares or similar 
voting rights of which is owned, directly or indirectly, by Pfizer or Cubist or 
any corporation or other legal entity fifty percent (50%) or more of the voting 
capital shares or similar voting rights of which is owned, directly or 
indirectly, by a corporation or other legal entity which owns, directly or 
indirectly, fifty percent (50%) or more of the voting capital shares or similar 
voting securities of Pfizer or Cubist. 

     1.2  "Research Plan" means the written plan describing the research to be 
           -------------
carried out by Pfizer and Cubist pursuant to this Agreement. The Research Plan 
and any amendments to it will be attached to and made a part of this Agreement 
as Exhibit 1.

     1.3  "Research Program" is the research program conducted by Pfizer and 
           ----------------     
Cubist in accordance with the Research Plan to discover and develop new 
antibacterial agents for the treatment of disease in human beings. 

     1.4  "Effective Date" is December 15, 1995.
           -------------- 

     1.5  "Contract Period" means the period beginning on the Effective Date and
           ---------------     
ending on the date on which this Agreement terminates. 

     1.6  "Area" means research or development with respect to Antibacterial 
           ----
Agents useful in the treatment or management of disease states in human beings.

     1.7  "Cubist Confidential Information" means all information about any 
           -------------------------------
element of the Cubist or Joint Technology which is disclosed by Cubist to Pfizer



<PAGE>
 
                                      3 

and designated "Confidential" in writing by Cubist at the time of disclosure to 
Pfizer to the extent that such information as of the date of disclosure to 
pfizer is not (i) demonstrably known to Pfizer other than by virtue of a prior 
confidential disclosure to Pfizer by Cubist; or (ii) disclosed in published 
literature, or otherwise generally known to the public through no fault or 
omission of Pfizer; or (iii) obtained from a third party free from any 
obligation of confidentiality to Cubist. 

     1.8   "Pfizer Confidential Information" means all information about any
            -------------------------------    
element of Pfizer or Joint Technology which is disclosed by Pfizer to Cubist and
designated "Confidential" in writing by Pfizer at the time of disclosure to 
Cubist to the extent that such information as of the date of disclosure to 
Cubist is not (i) demonstrably known to Cubists other than by virtue of a prior 
confidential to Cubist by Pfizer; or (ii) disclosed in published literature, or 
otherwise generally known to the public through no fault or omission of Cubist; 
or (iii) obtained from a third party free from any obligation of confidentiality
to Pfizer. 

     1.9   "Technology" means and includes all materials, technology, technical 
            ----------
information, know-how, expertise and trade secrets within the Area.

     1.10  "Cubist Technology" means Technology that is or was:
            -----------------

           (a)  known and developed by employees of or consultants to Cubist 
alone or jointly with third parties prior to the Effective Date; or

           (b)  acquired by purchase, license, assignment or other means from 
third parties by Cubist prior to the Effective Date. 

     1.11  "Joint Technology" means Technology that is or was:
            ----------------  
 
          (a)  developed by employees of or consultants to Pfizer or Cubist 
solely or jointly with each other during the Contract Period in connection with 
the performance of the Research Program or the Drug Discovery Program
<PAGE>
 
including, for example, but not by way of limitation, compounds previously
patented by Pfizer which Pfizer elects to develop pursuant to this Agreement; or

          (b) acquired by purchase, license, assignment or other means from 
third parties by Cubist or Pfizer during the Contract Period for use in the 
performance of the Research Program or the Drug Discovery Program.

     1.12 "Pfizer Technology" means Technology that is or was:
           -----------------

          (a) known and developed by employees of or consultants to Pfizer alone
or jointly with third parties prior to the Effective Date; or

          (b) acquired by purchase, license, assignment or to other means from 
third parties by Pfizer prior to the Effective Date.

     1.13 "Patent Rights" means all inventions deemed patentable claiming Joint
           -------------
Technology including all the valid claims of patent applications, whether 
domestic or foreign, claiming such patentable inventions, including all 
provisional applications, continuations, continuations-in-part, divisions, and 
renewals, all letters patent granted thereon, and all reissues, reexaminations 
and extensions thereof.

     1.14 "Product" means an Antibacterial Agent the manufacture, use or sale of
           -------
which would infringe Patent Rights in the absence of a license.

     1.15 "Antibacterial Agent" means a compound with inhibitory activity 
           -------------------
against a Program tRNA Synthetase.

     1.16 "Program tRNA Synthetases" means *************************************
           ------------------------
************************************************************************ 
******************************************************************

     1.17 "Hit" means a compound with inhibitory activity against a screened 
tRNA Synthetase which Pfizer selects for the Secondary Screening Program or as a
potential starting point for a Drug Discovery Program.




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<PAGE>
 
                                       5

     1.18 "Primary Screening Program" means assays conducted at Pfizer as set 
           -------------------------
forth in Exhibit 1B.

     1.19 "Secondary Screening Program" means assays conducted at Cubist as set 
           ---------------------------
forth in Exhibit 1C.

     1.20 "Drug Discovery Program" means that program for the development of an 
           ----------------------
Antibacterial Agent the criteria for which are set forth in Exhibit 1D.

     1.21 "Net Sales" means the gross amount invoiced by Pfizer and any
           ---------
sublicensee of Pfizer for sales to a third party or parties of Products, ****
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
*****

     1.22 "NDA" means New Drug Application.
           ---

2.   Research and Drug Discovery Programs
     ------------------------------------

     2.1  Purpose. Cubist and Pfizer shall conduct the Research Program and the
          -------
Drug Discovery Program, subject to the terms and conditions of this Agreement,
throughout the Contract Period. The objective of the Research and Drug Discovery
Programs is to discover and develop Products.

          2.1.1 The Research Program. The Research Program shall proceed as
               --------------------
follows:

          (a) No later than ********************************************* 
respectively, after the execution of this Agreement, Cubist will deliver each of
three sets of two tRNA synthetases set forth in Exhibit 1A to Pfizer.

          (b) Upon receipt of the six (6) tRNA synthetases, Pfizer shall employ 
these tRNA synthetases in screening its compound libraries in a manner





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<PAGE>
 
which in its sole judgment it finds suitable for such purpose; provided, 
however, that Pfizer shall have completed such screening, and sent samples of 
the Hits to Cubist no later than ******** after receipt of each set of the tRNA 
synthetases. After the ******* screening period is completed, Cubist shall have 
all rights to the Program tRNA Synthetases that have not yielded Hits.

          (c) Within 30 days of receipt of the Hits, Cubist will begin a 
Secondary Screening Program with respect to such Hits. The Secondary Screening 
Program will be completed and the results reported to Pfizer no later than * 
****** after Cubist's receipt of the Hits. After the Secondary Screening Program
is completed for each Hit, Cubist shall have all rights to the Program tRNA 
Synthetases except for such tRNA synthetases, if any, that are the primary 
target of a compound or compounds which enter a Drug Discovery Program.

          2.1.2 The Drug Discovery Program. Upon receipt of the results of the 
                --------------------------
Secondary Screening Program, Pfizer shall have ******* to designate a compound 
or compounds which the Research Committee recommends and Pfizer, in its sole 
unfettered discretion deems worthy for development as an Antibacterial Agent or 
Agents and to notify Cubist of such designation notification or to notify Cubist
that it will not designate any such compounds. Upon receipt of such notice, 
Cubist shall have 30 days to notify Pfizer that Cubist elects or does not elect 
to institute a Drug Discovery Program pursuant to the Research Plan if Pfizer 
has designated compound for development or, if Pfizer has not designated any 
compound for development, to select one compound screened in the Secondary 
Screening Program for development by itself or with third parties without 
further obligation to Pfizer. If Cubist elects to institute the Drug Discovery 
Program, this Agreement shall remain in full force and effect and shall govern 
the relationship between the parties with respect to such Antibacterial Agents. 
If Cubist does not elect to institute such Drug Development




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<PAGE>
 
Program, Pfizer shall be free to treat such Antibacterial Agents as it sees fit.
In such event, Cubist shall choose either of the payment options set forth in
Section 3.3(b) at the time it declines to institute such Drug Development 
Program and Pfizer's sole remaining obligation to Cubist, if any, shall pay the 
sums due upon the terms and conditions set forth pursuant to the chosen payment
option in that Section. 

        2.1.3 Research Plan. The Research Plan for the *********************
              -------------
period is described in the attached Exhibit 1. Any amendment to the Research
Plan shall be appended to Exhibit 1 and made part of this Agreement.

        2.1.4 Exclusivity.
              -----------
        (a)   Cubist agrees that during the Research Program and in the Area,
neither Cubist nor any of its Affiliates shall engage in any research sponsored
by any third party involving the use of the Program tRNA Synthetases for primary
screening purposes without Pfizer's consent.

        (b)   During the period of the Drug Discovery Program, whether conducted
by Cubist or Pfizer, Cubist shall likewise refrain from using any Program tRNA
Synthetase for which a Hit has been identified, carried through a Secondary
Screening Program and selected for such Drug Discovery Program in Cubist's own
research or research sponsored by third parties in the Area.

    2.2 Research Committee.
        ------------------
        2.2.1 Purpose. Pfizer and Cubist shall establish a Research
              -------
Committee (the "Research Committee"):

        (a)   to evaluate and recommend scientific criteria to be implemented 
under the Research Plan;

        (b)   to evaluate Hits based on the Primary Screening Program and 
recommend Hits to enter the Secondary Screening Program;






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                                      8 
 
          (c) to evaluate data from the Secondary Screening Program and make a 
recommendation to Pfizer to initiate Drug Discovery Program, if warranted;

          (d) to review and evaluate progress under the Research Plan;

          (e) to prepare amendments to the Research Plan; and

          (f) to coordinate and monitor publication of research results obtained
from and the exchange of information and materials that relate to the Research
Program.

          2.2.2 Membership. Pfizer and Cubist each shall appoint, in its sole
                ----------    
discretion, three members to the Research Committee. Substitutes may be 
appointed at any time.

     The members initially shall be:

     Pfizer Appointees:

                       William E. Kohlbrenner, Ph.D.
                       Manager, Infectious Diseases

                       Paul R. McGuirk, Ph.D.
                       Assistant Director, Medicinal Chemistry

                       Paul M. Sweetnam, Ph.D.
                       Manager, Drug Pfinder

     Cubist Appointees:

                       Francis P. Tally, M.D.
                       Vice President, Research & Development

                       Philip A. Wendler, Ph.D.
                       Director, Drug Discovery

                       Susan K. Whoriskey, Ph.D.
                       Director, Molecular Biology
<PAGE>
 
          2.2.3 Chair. The Research Committee shall be chaired by two 
                -----
co-chairpersons, one appointed by Pfizer and the other appointed by Cubist.
           
          2.2.4 Meetings. The Research Committee shall meet at least quarterly,
                --------
at places and on dates selected by each party in turn. Representatives of Pfizer
or Cubist or both, in addition to members of the Research Committee, may attend 
such meetings at the invitation of either party.
           
          2.2.5 Minutes. The Research Committee shall keep accurate minutes of
                ------- 
its deliberations which record all proposed decisions and all actions 
recommended or taken. Drafts of the minutes shall be delivered to all Research 
Committee members within five (5) business days after each meeting. The party 
hosting the meeting shall be responsible for the preparation and circulation of 
the draft minutes. Draft minutes shall be edited by the co-chairpersons and 
shall be issued in final form only with their approval and agreement.
            
          2.2.6 Decisions. All technical decisions of the Research Committee
                ---------
shall be made by majority of the members.
           
          2.2.7 Expenses. Pfizer and Cubist shall each bear all expenses of 
                --------
their respective members related to their participation on the Research 
Committee.
     
     2.3 Reports. During the Contract Period, Pfizer and Cubist each shall
         ------- 
furnish to the Research Committee:
           
           (a) summary written reports within fifteen (15) days after the end of
each three-month period commencing on the Effective Date, describing its
progress under the Research Plan or the Drug Discovery Program, as the case may
be; and
           (b) comprehensive written reports within thirty (30) days after the 
end of each year, describing in detail the work accomplished by it under the
<PAGE>
 
                                      10 

Research Plan or the Drug Discovery Program, as the case may be, and discussing 
and evaluating the results of such work.

     2.4 Laboratory Facilities and Personnel. Cubist and Pfizer each shall 
         -----------------------------------
provide suitable laboratory facilities, equipment and personnel for the work to 
be done in carrying out the Research Program and the Drug Discovery Program.

     2.5 Diligent Efforts. Pfizer and Cubist each shall use reasonably diligent
         ---------------- 
efforts to achieve the objectives of the Research Program and the Drug Discovery
Program, if performed by Cubist including without limitation the regulatory 
approval, promotion and sale of Products.

3.   Payments to Cubist.
     ------------------

     3.1 Receipt of Program Synthetases. Upon receipt of the first set of tRNA
         ------------------------------ 
synthetases described in Section 2.1.1(a), Pfizer shall pay Cubist the sum of 
**********  *****  ***  *** ** *********** set forth in Exhibit 3. The parties 
acknowledge that the sum set forth in Exhibit 3 is an estimate and that actual 
costs may reach **************. Accordingly, Cubist agrees to furnish to Pfizer 
invoices and supporting financial documentation evidencing all expenditures 
pursuant to Exhibit 3.

     3.2 Secondary Screening Program. Within thirty (30) days of the initiation 
         ---------------------------
of a Secondary Screening Program, Pfizer shall pay Cubist the sum of ***********
as set forth in Exhibit 4. The parties acknowledge that the sum set forth in 
Exhibit 4 is an estimate and that actual costs may reach **************.
Accordingly, Cubist agrees to furnish to Pfizer invoices and supporting 
financial documentation evidencing all expenditure pursuant to Exhibit 4.

     3.3 Drug Discovery Program.
         ----------------------

         (a) Discovery Program performed by Cubist. (i) Upon receipt of notice 
             -------------------------------------
that Cubist elects to perform the Drug Discovery Program, Pfizer shall





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<PAGE>
 
                                      11 

execute a Stock Purchase Agreement and shall forward it to Cubist within fifteen
(15) days of the receipt of such notice. In turn, Cubist shall have fifteen (15)
days to execute the Stock Purchase Agreement and to return it to Pfizer. Upon 
receipt of the fully executed Stock Purchase Agreement, Pfizer shall, forthwith,
wire transfer the sum ************* to Cubist in accordance with that agreement.
(ii) The purchase price ("Price") of the stock described in the Stock Purchase 
Agreement shall be determined as follows: (a) If Cubist's stock is publicly 
traded, the price shall ********************************************************
**************************************************************************** of
********************************************************************************
******************************************************************** and (b) If 
Cubist's stock is not publicly traded, the price shall be ****** per share on 
January 1, 1996 and ****** per share on December 31, 1996 and thereafter 
appropriately adjusted for stock splits, reverse splits, combinations or the 
like. During 1996, the price shall be pro rated on a daily basis. (iii) In 
addition, if the Drug Discovery Program yields a compound which, Pfizer, *******
************************** determines to advance as an Antibacterial Agent, 
Pfizer will make the following payments to Cubist on the occurrence of each 
event ("Event") set forth below; provided, however, that Pfizer shall be 
obligated to make only one payment with respect to each Event affecting an 
Antibacterial Agent; and, further provided, that Pfizer  may, in its sole, 
unfettered discretion discontinue the development of any Antibacterial Agent at 
any time irrespective of its scientific or medical merit:

<TABLE> 
<CAPTION>                  
            Event                                    Payment
            -----                                    -------
<S>                                                <C> 
Pfizer Acceptance of Drug Discovery               ****************
Program Results                         
</TABLE> 





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                                      12

Evaluation of Safety Data of the First                   *************
300 Subjects treated with the
Antibacterial Agent

Initiation of Phase III Trials                           *************

Filing of NDA                                            *************

Approval of NDA                                          *************

All payments made pursuant to this Section shall be credited against the 
royalties described below.  (iii) If the Antibacterial Agent described above 
would in the absence of the license set forth in Section 4.3 infringe Patent 
Rights, the royalty paid by Pfizer to Cubist shall be the sum of the Net Sales 
in each Tier multiplied by the applicable royalty rate for that Tier:

 Annual Net Sales (in $ millions)
 --------------------------------
             ("Tiers")                              Percentage of Net Sales
             ---------                              -----------------------
              ***************************************************
            ****************************************************
           ******************************************************
         ********************************************************
(iv) If Pfizer discontinues development of any Antibacterial Agent described in 
this Section 3.3(a) for any reason other than results of clinical safety or 
toleration studies which Pfizer, in any case, in its sole, unfettered discretion
deems unsatisfactory, or if the U.S. Food and Drug Administration ("FDA") refuse
to grant any approval required for the development of such Agent, Pfizer will, 
at Cubist's option, grant to Cubist a worldwide exclusive license in the form 
attached as Exhibit 5 to make, use and sell any such Antibacterial Agent under 
all





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<PAGE>
 
                                      13

Pfizer's right, title and interest in all Cubist, Pfizer or jointly owned 
patents claiming such Agent as well as information reasonably required for 
registration with the FDA or equivalent foreign agencies. Cubist will pay a 
royalty to Pfizer based on the state of development of each such Antibacterial 
Agent as set forth in the chart below:

<TABLE> 
<CAPTION> 
                                                          Royalty
                                                          -------
<S>                                          <C>       
Pfizer discontinues development at any                     ****
time prior to completion of Phase I
Pfizer declines entry into Phase II                        ****
Pfizer declines entry into Phase III                       ****
Pfizer declines NDA registration                          *******
                                             **********************************
                                                      **************
</TABLE> 

If Pfizer discontinues development because of the study results or failure to 
obtain FDA approval mentioned above, Pfizer shall be under no obligation to 
grant the described license or any other right to Cubist with respect to the 
affected Antibacterial Agent.
           (b) ************************************************************
               ------------------------------------------------
********************************************************************************
********************************************************************




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<PAGE>
 
                                      14
 
**************************************************************************** 
*******************************************************************

<TABLE> 
<CAPTION> 
                                       A
                                       -
                       Event                        Payment
                       -----                         -------
             <S>                                   <C> 
             Initiation of a Pfizer
             Discovery Program                     *********** 

             Acceptance of a Standard                  
             Pfizer Recommendation
             for Development                       ************

             Commencement of Pfizer
             Phase I Study                         ************

             Commencement of Pfizer
             Phase III Study                       ************

             Pfizer NDA Approved                   *************
</TABLE> 
Pfizer shall pay the sums due within thirty (30) days of the occurrence of an
Event; provided, however, that Pfizer shall be under no obligation whatever to
advance an Antibacterial Agent so that an Event occurs. ************************
**************************************************************************
********************************************************************************
**************************************************************************
****************************************************************************
************************************ In addition to the payments described
above, if Pfizer, in the sole, unfettered discretion, decides to sell such
Antibacterial Agent, Pfizer will pay Cubist **************** of Net Sales or the
Net Sales of     
  





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<PAGE>
 
                                      15

its sublicensees in all countries in which the Antibacterial Agent is patented 
during the life of such patents.

<TABLE> 
<CAPTION> 
                                       B
                                       -
                  Event                                  Payment
                  -----                                  -------
           <S>                                        <C> 
           Initiation of a Pfizer
           Discovery Program                          **************

           Acceptance of a Standard
           Pfizer Recommendation
           for Development                             *************

           Commencement of Pfizer
           Phase I Study                                ************

           Commencement of Pfizer
           Phase III Study                             *************

           Pfizer NDA Filed                            *************

           Pfizer NDA Approved                         *************
</TABLE> 

Pfizer shall pay the sums due within thirty (30) days of the occurrence of an 
Event; provided, however, that Pfizer shall be under no obligation whatever to 
advance a Antibacterial Agent so that an Event occurs. ************************ 
************************************************************************
********************************************************************************
***************************************************************************** 
************************************************************* If Cubist fails to
make such election, it shall be deemed to have chosen Schedule A. Pfizer shall 
make or not make such payments, as the case may be, on the same terms and 
conditions set forth in Section 3.3(a)(ii), above.




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<PAGE>
 
                                      16

4.  Intellectual Property Rights. The following provisions relate to rights in 
    ----------------------------
the intellectual property developed by Cubist or Pfizer, or both, during the 
course of carrying out the Research Program.

    4.1  Ownership. All Cubist Confidential Information and Cubist Technology 
         ---------
shall be owned by Cubist. All Pfizer Confidential Information and Pfizer 
Technology shall be owned by Pfizer. All Joint Technology shall be owned jointly
by Cubist and Pfizer. All Patent Rights shall be assigned to and owned by 
Cubist, Pfizer or jointly by both of them in accordance with their inventorship.

    4.2 Grants of Research Licenses. Cubist and Pfizer each grants to the other 
        ---------------------------
a nonexclusive ************** worldwide, royalty-free, ********** license, 
including the right to grant sublicenses to Affiliates, to make and use 
Confidential Information, Technology and Patent Rights for all research purposes
other than the sale or manufacture for sale of products or processes.

    4.3 License Granted to Pfizer under the Patent Rights. Cubist grants to 
        -------------------------------------------------
Pfizer the exclusive, worldwide license, including the right to grant 
sublicenses, to manufacture, use and sell Products under all Cubist's right, 
title and interest in the Patent Rights (the "License").

    4.4 Term of License Grant and Payment of Royalties. Unless terminated 
        ----------------------------------------------
earlier, the License shall commence on the Effective Date and shall terminate on
the date of the last to expire of the Patent Rights. The License shall also  
terminate if (a) no Hits are identified by the Research Committee; or (b) no 
compound enters the Drug Discovery Program; or (c) no compound is accepted by 
Pfizer in its sole unfettered discretion for advancement for drug development; 
or (d) no NDA or foreign equivalent is approved.

    4.5 Pfizer Obligations. If Pfizer grants a sublicense pursuant to this 
        ------------------
Section, Pfizer shall guarantee that any sublicense fulfills all of Pfizer's




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<PAGE>
 
                                      17 

obligations under the Agreement; provided, however, that Pfizer shall not be 
relieved of its obligations pursuant to this Agreement.

     4.6 Cubist Obligations. If Cubist declines to conduct a Drug Discovery 
         ------------------
Program, as described in Section 3.3(b), Cubist will provide technical support 
to Pfizer to produce the tRNA synthetases designated for the Drug Discovery 
Program, at Pfizer's cost.

5. Payments of Royalties, Accounting for Royalties Records.
   -------------------------------------------------------

     5.1 Royalty Obligation. Pfizer shall pay Cubist a royalty based on the Net
         ------------------ 
Sales of each Product. Such royalty shall be paid with respect to each country 
of the world from the date of the first commercial sale (the date of the invoice
of Pfizer or any sublicensee of Pfizer with respect to such sale of such Product
in each country until the expiration of the last Patent Right to expire with
respect to each such country and each such Product.

     5.2 Payment Dates. Royalties shall be paid by Pfizer on Net Sales within 
         -------------
sixty (60) days after the end of each calendar quarter in which such Net Sales 
are made. Such payments shall be accompanied by a statement showing the Net 
Sales of each Product by Pfizer or any sublicensee of Pfizer in each country, 
the applicable royalty rate for such Product, and a calculation of the amount of
royalty due.

     5.3 Accounting. The Net Sales used for computing the royalties payable to
         ---------- 
Cubist by Pfizer shall be computed and paid in U.S. dollars by check or other 
mutually acceptable means. For purposes of determining the amount of royalties 
due, the amount of Net Sales in any foreign currency shall be computed by (a) 
converting such amount into dollars at the prevailing commercial rate of 
exchange for purchasing dollars with such foreign currency as quoted by Citibank
in New York on the last business day of the calendar quarter for which

<PAGE>
 
the relevant royalty payment is to be made by Pfizer and (b) deducting the 
amount of any governmental tax, duty, charge, or other fee actually paid in 
respect of such conversion into, and remittance of dollars.

     5.4 Records. Pfizer shall keep for three (3) years from the date of each 
         -------
payment of royalties complete and accurate records of sales by Pfizer of each 
Product in sufficient detail to allow the accruing royalties to be determined 
accurately. Cubist shall have the right for a period of three (3) years after 
receiving any report or statement with respect to royalties due and payable to 
appoint at its expense an independent certified public accountant reasonably 
acceptable to Pfizer to inspect the relevant records of Pfizer to verify such 
report or statement. Pfizer shall make its records available for inspection by 
such independent certified public accountant during regular business hours at 
such place or places where such records are customarily kept, upon reasonable 
notice from Cubist, to verify the accuracy of the reports and payments. Such 
inspection right shall not be exercised more than once in any calendar year nor 
more than once with respect to sales in any given period. Cubist agrees to hold 
in strict confidence all information concerning royalty payments and reports, 
and all information learned in the course of any audit or inspection, except to 
the extent necessary for Cubist to reveal such information in order to enforce 
its rights under this Agreement or if disclosure is required by law. The failure
of Cubist to request verification of any report or statement during said 
three-year period shall be considered acceptance of the accuracy of such report,
and Pfizer shall have no obligation to maintain records pertaining to such 
report or statement beyond said three-year period. The results of each 
inspection, if any, shall be binding on both parties.
<PAGE>
 
                                      19 

6. Legal Action.
   ------------

     6.1 Actual or Threatened Disclosure or Infringement. When information comes
         -----------------------------------------------
to the attention of Pfizer to the effect that any Patent Rights relating to a 
Product have been or are threatened to be unlawfully infringed, Pfizer shall 
have the right at its expense to take such action as it may deem necessary to 
prosecute or prevent such unlawful infringement, including the right to bring or
defend any suit, action or proceeding involving any such infringement. Pfizer 
shall notify Cubist promptly of the receipt of any such information and of the 
commencement of any such suit, action or proceeding. If Pfizer determines that 
it is necessary or desirable for Cubist to join any such suit, action or 
proceeding, Cubist shall, at Pfizer's expense, execute all papers and perform 
such other acts as may be reasonably required to permit Pfizer to act in 
Cubist's name in which event Pfizer shall hold Cubist free, clear and harmless
from any and all costs of such litigation including attorney's fees. If Pfizer
brings a suit, it shall have the right first to reimburse itself out of any sums
recovered in such suit or in its settlement for all costs and expenses,
including attorney's fees, related to such suit or settlement, *****************
********************************************************************************
********************************************************************************
If Pfizer does not, within one hundred twenty (120) days after giving notice to
Cubist of the above-described information, notify Cubist of Pfizer's intent to
bring suit against any infringer, Cubist shall have the right to bring suit for
such alleged infringement, but it shall not be obligated to do so, and may join
Pfizer as party plaintiff, if appropriate, in which event Cubist shall hold
Pfizer free, clear and harmless from any and all costs and expenses of such
litigation, including attorney's fees, and any sums recovered in any such suit
or in its settlement shall belong to Cubist. ***********************************
****************************************************




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<PAGE>
 
                                      20 

*******************************************************************************
*********************************************. Each party shall always have the 
right to be represented by counsel of its own selection and at its own expense 
in any suit instituted by the other for infringement under the terms of this 
Section. If Pfizer lacks standing and Cubist has standing to bring any such 
suit, action or proceeding, then Cubist shall do so at the request of Pfizer and
at Pfizer's expense.

7. Defense of Infringement Claims. Cubist will cooperate with Pfizer at Pfizer's
   ------------------------------
expense in the defense of any suit, action or proceeding against Pfizer or any 
sublicensee of Pfizer alleging the infringement of the intellectual property 
rights of a third party by reason of the use of Patent Rights in the 
manufacture, use or sale of the Product. Pfizer shall give Cubist prompt written
notice of the commencement of any such suit, action or proceeding or claim of 
infringement and will furnish Cubist a copy of each communication relating to 
the alleged infringement. Cubist shall give to Pfizer all authority (including 
the right to exclusive control of the defense of any such suit, action or 
proceeding and the exclusive right after consultation with Cubist, to 
compromise, litigate, settle or otherwise dispose of any such suit, action or 
proceeding), information and assistance necessary to defend or settle any such 
suit, action or proceeding; provided, however, Pfizer shall obtain Cubist's 
prior consent to such part of any settlement which requires payment or other 
action by Cubist or has a material adverse effect on Cubist's business. If the 
parties agree that Cubist should institute or join any suit, action or 
proceeding pursuant to this Section, Pfizer may, at Pfizer's expense, join 
Cubist as a defendant if necessary or desirable, and Cubist shall execute all 
documents and take all other actions, including giving




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<PAGE>
 
testimony, which may reasonably be required in connection with the prosecution 
of such suit, action or proceeding

8. Treatment of Confidential Information
   -------------------------------------

   8.1 Confidentiality
       ---------------

       8.1.1 Pfizer and Cubist each recognize that the other's Confidential 
Information constitutes highly valuable, confidential information. Subject to 
the terms and conditions of the License, the obligations set forth in Section 
8.3 and the publication rights set forth in Section 8.2, Pfizer and Cubist each 
agree that during the term of this Agreement and for five (5) years thereafter, 
it will keep confidential, and will cause its Affiliates to keep confidential, 
all Cubist Confidential Information or Pfizer Confidential Information, as the 
case may be, that is disclosed to it, or to any of its Affiliates pursuant to 
this Agreement. Neither Pfizer nor Cubist nor any of their respective Affiliates
shall use such Confidential Information except as expressly permitted in this 
Agreement.

      8.1.2 Pfizer and Cubist each agree that any disclosure of the other's 
Confidential Information to any officer, employee or agent of the other party or
of any of its Affiliates shall be made only if and to the extent necessary to 
carry out its responsibilities under this Agreement and shall be limited to the 
maximum extent possible consistent with such responsibilities. Pfizer and Cubist
each agree not to disclose the other's Confidential Information to any third 
parties under any circumstance without written permission from the other party. 
Each party shall take such action, and shall cause its Affiliates to take such 
action, to preserve the confidentiality of each other's Confidential Information
as it would customarily take to preserve the confidentiality of its own 
Confidential Information. Each party, upon the other's request, will return all 
the Confidential Information disclosed to the other party pursuant to this 
Agreement, including all copies and
<PAGE>
 
                                      22

extracts of documents, within sixty (60) days of the request upon the 
termination of this Agreement except for one (1) copy which may be kept for the 
purpose of complying with continuing obligations under this Agreement.

           8.1.3 Cubist and Pfizer each represent that all of its employees, and
any consultants to such party, participating in the Research Program who shall 
have access to Pfizer Technology, Cubist Technology or Joint Technology and 
Pfizer Confidential Information and Cubist Confidential Information are bound by
agreement to maintain such information in confidence.

     8.2 Publication. Notwithstanding any matter set forth with particularity in
         -----------
this Agreement to the contrary, results obtained in the course of the Research
Program may be submitted for publication following scientific review by the
Research Committee and subsequent approval by Cubist's and Pfizer's managements,
which approval shall not be unreasonably withheld. After receipt of the proposed
publication by both Pfizer's and Cubist's managements written approval or
disapproval shall be provided within thirty (30) days for a manuscript, within
fourteen (14) days for an abstract for presentation at, or inclusion in the
proceedings of a scientific meeting, and within fourteen (14) days for a
transcript of an oral presentation to be given at a scientific meeting.

     8.3 Publicity. Except as required by law, neither party may disclose the
         --------- 
terms of this Agreement nor the research described in it without the written 
consent of the other party, which consent shall not be unreasonably withheld.

     8.4 Disclosure of Inventions. Each party shall promptly inform the other
         ------------------------ 
about all inventions in the Area that are conceived, made or developed in the 
course of carrying out the Research Program or the Drug Discovery Program if 
performed by Cubist by employees of, or consultants to, either of them solely, 
or jointly with employees of, or consultants to the other.
<PAGE>
 
                                      23

9. Provisions Concerning the Filing, Prosecution and Maintenance of Patent
   -----------------------------------------------------------------------
Rights. The following provisions relate to the filing, prosecution and 
- ------
maintenance of Patent Rights during the term of this Agreement: 

     9.1 Filing, Prosecution and Maintenance by Cubist. With respect to Patent
         ---------------------------------------------
Rights in which Cubist employees or consultants, alone or together with Pfizer
employees, or consultants are named as inventors, Cubist shall have the
exclusive right and obligation:

         (a) to file applications for letters patent on any invention deemed
patentable included in Patent Rights; provided, however, that Cubist shall
consult with Pfizer regarding countries in which such patent applications should
be filed and shall file patent applications in those countries where Pfizer 
requests that Cubist file such applications; and, further provided, that Cubist,
at its option and expense, may file in countries where Pfizer does not request
that Cubist file such applications;

         (b) to take all reasonable steps to prosecute all pending and new
patent applications included within Patent Rights;
 
         (c) to respond to oppositions, nullity actions, re-examinations,
revocation actions and similar proceedings filed by third parties against the
grant of letters patent for such applications;

         (d) to maintain in force any letters patent included in Patent Rights 
by duly filing all necessary papers and paying any fees required by the patent 
laws of the particular country in which such letters patent were granted; and

         (e) to cooperate fully with, and take all necessary actions requested 
by, Pfizer in connection with the preparation, prosecution and maintenance of 
any letters patent included in Patent Rights.

         Cubist shall notify Pfizer in a timely manner of any decision to 
abandon a pending patent application or an issued patent included in Patent 
Rights.
     
<PAGE>
 
                                      24

Thereafter, Pfizer shall have the option, at its expense, of continuing to 
prosecute any such pending patent application or of keeping the issued patent in
force:

          9.1.1 Copies of Documents. Cubist shall provide to Pfizer copies of 
                -------------------
all patent applications that are part of Patent rights prior to filing, for the 
purpose of obtaining substantive comment of Pfizer patent counsel.  Cubist shall
also provide to Pfizer copies of all documents relating to prosecution of all 
such patent applications in a timely manner and shall provide to Pfizer every 
six (6) months a report detailing their status.  Pfizer shall provide to Cubist 
every six (6) months a report detailing the status of all patent applications 
that are a part of Patent Rights in which Pfizer employees or consultants alone 
are named as inventors.

          9.1.2 Reimbursement of Costs for Filing Prosecuting and Maintaining 
                -------------------------------------------------------------
Patent Rights. Within thirty (30) days of receipt of invoices from Cubist, 
- -------------
Pfizer shall reimburse Cubist for all the costs of filing, prosecuting, 
responding to opposition and maintaining patent applications and patents in 
countries where Pfizer requests that patent applications be filed, prosecuted 
and maintained. Such reimbursement shall be in addition to Funding Payments. 
However, Pfizer may, upon sixty (60) days notice, request that Cubist 
discontinue filing or prosecution of patent applications in any country and 
discontinue reimbursing Cubist for the costs of filing, prosecuting, responding 
to opposition or maintaining such patent application or patent in any country. 
Cubist shall pay all costs in those countries in which Pfizer does not request 
that Cubist file, prosecute or maintain patent applications and patents, but in 
which Cubist, at its option, elects to do so.

          9.1.3 Pfizer shall have the right to file on behalf of and as an agent
for Cubist all applications and take all actions necessary to obtain patent 
extensions pursuant to 35 USC Section 156 and foreign counterparts for Patent
<PAGE>
 
                                      25 

Rights described in this Section 9.1 licensed to Pfizer. Cubist agrees, to sign,
at Pfizer's expense, such further documents and take such further actions as may
be requested by Pfizer in this regard.

     9.2  Filing, Prosecution and Maintenance by Pfizer. With respect to Patent 
          ---------------------------------------------
Rights in which Pfizer employees or consultants alone are named as inventors, 
Pfizer shall have those rights and duties ascribed to Cubist in Section 9.1.

     9.3  Neither party may disclaim a Valid Claim within Patent Rights without 
the consent of the other.


10.  Acquisition of Rights from Third Parties. During the Contract Period, 
     ----------------------------------------   
Cubist and Pfizer shall each promptly notify each other of any and all 
opportunities to acquire in any manner from third parties, technology or patents
or information which may be useful in or may relate to the Research Program or 
the Drug Discovery Program, if performed by Cubist. Cubist and Pfizer shall 
decide if such rights should be acquired in connection with the Research Program
and, if so, whether by Cubist, Pfizer or both.


11.  Sole Agreement. This Agreement is the sole agreement with respect to the 
     -------------- 
subject matter and supersedes all other agreements and understandings between 
the parties with respect to same.


12.  Term, Termination and Disengagement.
     -----------------------------------

     12.1 Term. Unless sooner terminated or extended, this Agreement shall 
          ----
expire on June 15, 1997.

     12.2 Events of Termination. The following events shall constitute events of
          ---------------------
termination ("Events of Termination"):
<PAGE>
 
                                      26

           (a)  any written representation or warranty by Cubist or Pfizer, or 
any of its officers, made under or in connection with this Agreement shall prove
to have been incorrect in any material respect when made.

           (b)  Cubist or Pfizer shall fail in any material respect to perform 
or observe any term, covenant or understanding contained in this Agreement or in
any of the other documents or instruments delivered pursuant to, or concurrently
with, this Agreement, and any such failure shall remain unremedied for thirty
(30) days after written notice to the failing party.

     12.3  Termination.
           -----------

           12.3.1  Upon the occurrence of any Event of Termination, the party 
not responsible may, by notice to the other party, terminate this Agreement.

           12.3.2  If Pfizer terminates this Agreement pursuant to Section 
12.3.1, *************************************************. If Cubist terminates 
this Agreement pursuant to Section 12.3.1, the License shall terminate 
immediately. 

           12.3.3  ******************************************************** 
***************************************************************************
*********.

13.  Representations and Warranties. Cubist and Pfizer each represents and 
     ------------------------------     
warrants as follows:

     13.1  It is a corporation duly organized, validly existing and is in good 
standing under the laws of the State of Delaware, is qualified to do business 
and is in good standing as a foreign corporation in each jurisdiction in which 
the conduct of its business or the ownership of its properties requires such 
qualification and has all requisite power and authority, corporate or otherwise,
to conduct its business as now being conducted, to own, lease and operate its
properties and to execute, deliver and perform this Agreement.




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      27

     13.2 The execution, delivery and performance by it of this Agreement have 
been duly authorized by all necessary corporate action and do not and will not 
(a) require any consent or approval of its stockholders, (b) violate any 
provision of any law, rule, regulations, order, writ, judgment, injunctions, 
decree, determination award presently in effect having applicability to it or 
any provision of its certificate of incorporation or by-laws or (c) result in a 
breach of or constitute a default under any material agreement, mortgage, lease,
license, permit or other instrument or obligation to which it is a party or by 
which it or its properties may be bound or affected.

     13.3 This Agreement is a legal, valid and binding obligation of it 
enforceable against it in accordance with its terms and conditions, except as 
such enforceability may be limited by applicable bankruptcy, insolvency, 
moratorium, reorganization or similar laws, from time to time in effect, 
affecting creditor's rights generally.

     13.4 It is not under any obligation to any person, or entity, contractual 
or otherwise, that is conflicting or inconsistent in any respect with the terms 
of this Agreement or that would impede the diligent and complete fulfillment of 
its obligations.

     13.5 It has good and marketable title to or valid leases or licenses for, 
all of its properties, rights and assets necessary for the fulfillment of its 
responsibilities under the Research Program, subject to no claim of any third 
party other than the relevant lessors or licensors.

14. Covenants of Cubist and Pfizer Other Than Reporting Requirements.
    ----------------------------------------------------------------

Throughout the Contract Period, Cubist and Pfizer each shall:

     14.1 maintain and preserve its corporate existence, rights, franchises and 
privileges in the jurisdiction of its incorporation, and qualify and remain
<PAGE>
 
                                      28

qualified as a foreign corporation in good standing in each jurisdiction in
which such qualification is from time to time necessary or desirable in view of
their business and operations or the ownership of their properties.

     14.2 comply in all material respects with the requirements of all 
applicable laws, rules, regulations and orders of any government authority to 
the extent necessary to conduct the Research Program, except for those laws, 
rules, regulations, and orders it may be contesting in good faith.

15. Indemnification. Pfizer will indemnify Cubist for damages, settlements, 
    ---------------
costs, legal fees and other expenses incurred in connection with a claim against
Cubist based on any action, omission or the manufacture, use or sale of the 
Product by Pfizer, its agents or employees related to the obligations of Pfizer 
under this Agreement; provided, however, that the foregoing shall not apply (i) 
if the claim is found to be based upon the negligence, recklessness or willful 
misconduct of Cubist or (ii) if Cubist fails to give Pfizer prompt notice of any
claim it receives and such failure materially prejudices Pfizer with respect to 
any claim or action to which Pfizer's obligation pursuant to this Section 
applies. Pfizer, in its sole discretion, shall choose legal counsel, shall 
control the defense of such claim or action and shall have the right to settle 
same on such terms and conditions it deems advisable; provided, however, it 
shall obtain Cubist's prior consent to such part of any settlement which 
requires payment or other action by Cubist or is likely to have a material 
adverse effect on Cubist's business.

16. Notices. All notices shall be in writing mailed via certified mail, return 
    -------
receipt requested, courier, or facsimile transmission addressed as follow or to 
such other address as may be designated from time to time:






<PAGE>
 
                                      29

     If to Pfizer:          To Pfizer at its address as set forth at the
                            beginning of this Agreement.
                            Attention: President, Central Research
                            with copy to: Office of the General Counsel.

     If to Cubist:          Cubist at its address as set forth at the beginning 
                            of this Agreement.
                            Attention: President

Notices shall be deemed given as of the date received.

17. Governing Law. This Agreement shall be governed by and construed in
    ------------- 
accordance with the laws of the State of New York.

18. Miscellaneous.
    -------------

     18.1 Binding Effect. This Agreement shall be binding upon and inure to the 
          --------------
benefit of the parties and their respective legal representatives, successors 
and permitted assigns.

     18.2 Headings. Paragraph headings are inserted for convenience of reference
          --------
only and do not form a part of this Agreement.

     18.3 Counterparts. This Agreement may be executed simultaneously in two or
          ------------ 
more counterparts, each of which shall be deemed an original.

     18.4 Amendment, Waiver. This Agreement may be amended, modified, superseded
          -----------------
or canceled, and any of the terms may be waived, only by a written instrument
executed by each party or, in the case of waiver, by the party or parties
waiving compliance. The delay or failure of any party at any time or times to
require performance of any provisions shall in no manner affect the rights at a
later time to enforce the same. No waiver by any party of any condition or of
the breach of any term contained in this Agreement, whether by conduct, or
otherwise, in any one or more instances, shall be deemed to be, or
<PAGE>
 
                                      30
 
considered as, a further or continuing waiver of any such condition or of the 
breach of such term or any other term of this Agreement.

     18.5 No Third Party Beneficiaries. No third party including any employee of
          ----------------------------
any party to this Agreement, shall have or acquire any rights by reason of this 
Agreement. Nothing contained in this Agreement shall be deemed to constitute the
parties partners with each other or any third party.

     18.6 Assignment and Successors. This Agreement may not be assigned by 
          -------------------------
either party, except that each party may assign this Agreement and the rights 
and interests of such party, in whole or in part, to any of its Affiliates, any 
purchaser of all or substantially all of its assets or to any successor 
corporation resulting from any merger or consolidation of such party with or 
into such corporations.

     18.7 Force Majeure. Neither Pfizer nor Cubist shall be liable for failure 
          -------------
of or delay in performing obligations set forth in this Agreement, and neither 
shall be deemed in breach of its obligations, if such failure or delay  is due 
to natural disasters or any causes reasonably beyond the control of Pfizer or 
Cubist. 

     18.8 Severability. If any provision of this Agreement is or becomes invalid
          ------------
or is ruled invalid by any court of competent jurisdiction or is deemed
unenforceable, it is the intention of the parties that the remainder of the
Agreement shall not be affected.

<PAGE>
 
                                      31


IN WITNESS WHEREOF, the parties have caused this Agreement to be executed by 
their duly authorized representatives.


                                       PFIZER INC

                                       By [signature appears here]
                                         ----------------------------



                                       CUBIST PHARMACEUTICALS, INC.

                                       By [signature appears here]
                                         ----------------------------



cc:  Pfizer Inc, Legal Division, Groton, CT 06340


<PAGE>
 
                                                                    EXHIBIT 10.8

                            Confidential Treatment
 
                  COLLABORATIVE RESEARCH AND LICENSE AGREEMENT

This COLLABORATIVE RESEARCH AND LICENSE AGREEMENT is entered into as of June 13,
1996 by and between MERCK & CO., INC. ("MERCK"), a New Jersey corporation having
an office at One Merck Drive, Whitehouse Station, New Jersey 08889, and CUBIST
PHARMACEUTICALS, INC. ("CUBIST"), a Delaware corporation having an office at 24
Emily Street, Cambridge, Massachusetts 02139.


WHEREAS, CUBIST has expertise in the biochemistry and molecular biology of tRNA
synthetases from microorganism and human sources; and


WHEREAS, MERCK and CUBIST have the scientific expertise and capacity to
undertake the "COLLABORATION" (as defined in Article 1) contemplated by this
Agreement; and


WHEREAS, MERCK has the capability to undertake development of "ANTI-INFECTIVE
AGENTS" (as defined in Article 1); and


WHEREAS, MERCK possesses libraries of compounds and natural products and desires
to determine the enzyme inhibitory capability of each compound in such library
against CUBIST's tRNA synthetases targets in a "PRIMARY SCREENING PROGRAM" (as
defined in Article 1); and


WHEREAS, MERCK shall compensate CUBIST for access to CUBIST's technology, shall
provide to CUBIST research funding for preparing the 
<PAGE>
 
                                      -2-
 
tRNA synthetase targets and conducting the RESEARCH PLAN described in Exhibit 2
and shall pay CUBIST additional amounts based on the achievement of certain
milestones and of certain commercial sales of LICENSED PRODUCT(S).


NOW, THEREFORE, in consideration of the foregoing premises and the covenants set
forth below the parties agree as follows:


1.0  DEFINITIONS
     Whenever used in this Agreement, the capitalized terms defined in this
     Article 1.0 shall have the meanings specified.

     1.1  "AFFILIATE" means any corporation or other legal entity owning,
           ---------                                                     
          directly or indirectly, more than fifty percent (50%) of the voting
          capital shares or similar voting securities of MERCK or CUBIST; any
          corporation or other legal entity more than fifty percent (50%) of the
          voting capital shares or similar voting rights of which is owned,
          directly or indirectly, by MERCK or CUBIST; or any corporation or
          other legal entity more than fifty percent (50%) of the voting capital
          shares or similar voting rights of which is owned, directly or
          indirectly, by a corporation or other legal entity which owns,
          directly or indirectly, more than fifty percent (50%) of the voting
          capital shares or similar voting securities of MERCK or CUBIST.
<PAGE>
 
                                      -3-
 
     1.2  "AMINOACYL-tRNA SYNTHETASES" means *********************
           --------------------------                                         

     1.3  "ANTI-INFECTIVE AGENT" means any compound resulting from the
           --------------------                                       
          COLLABORATION with inhibitory activity ***********************

     1.4  "AREA" means research or development with respect to ANTI-INFECTIVE
           ----                                                              
          AGENTS useful in the prevention, treatment or management of any
          disease states in human beings, animals or plants.

     1.5. "BASE MILESTONE PAYMENT" means that amount calculated pursuant to
           ----------------------                                          
          Section 3.5 hereof.

     1.6  "BIOLOGICAL MATERIALS" means any material having a biological
           --------------------                                        
          activity, including, but not limited to, structural genes, genetic
          sequences, promoters, enhancers, probes, linkage probes, vectors,
          plasmids, transformed cell lines, bacterial strains, transgenic
          animals, proteins and fragments thereof, peptides, biological
          modifiers, antigens, antibodies, cell lines, antagonists, agonists,
          inhibitors and other biologically active materials.




                     
                     
                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -4-
 
     1.7  "COLLABORATION" means the research collaboration to be conducted by
           -------------                                                     
          MERCK and CUBIST pursuant to this Agreement.  Exhibit 1 hereto sets
          forth a diagram outlining the COLLABORATION.

     1.8  "COMPOUND" means any chemical entity or natural product sample that is
           --------                                                             
          identified as a HIT or synthesized in the MEDICINAL CHEMISTRY AND DRUG
          DISCOVERY PROGRAM; provided, however, that the term "COMPOUND" shall
                             --------  -------                                
          not mean or include any RESTRICTED COMPOUND.

     1.9  "CONFIDENTIAL INFORMATION" means, collectively, MERCK CONFIDENTIAL
           ------------------------                                         
          INFORMATION and CUBIST CONFIDENTIAL INFORMATION.

     1.10 "CUBIST" means CUBIST PHARMACEUTICALS, INC. and its AFFILIATES.
           ------                                                        

     1.11 "CUBIST CONFIDENTIAL INFORMATION" means all information which is
           -------------------------------                                
          disclosed by CUBIST to MERCK, either orally or in writing, in the
          course of the COLLABORATION to the extent that such information as of
          the date of disclosure to MERCK is not (i) known to MERCK (as
          evidenced in its records) other than by virtue of a prior confidential
          disclosure to MERCK by CUBIST; or (ii) disclosed in published
          literature, or otherwise generally available to the public 
<PAGE>
 
                                      -5-
 
          through no fault or omission of MERCK; or (iii) obtained from a third-
          party free from any obligation of confidentiality to CUBIST; or (iv)
          developed by MERCK (as evidenced in writing) independent of the CUBIST
          CONFIDENTIAL INFORMATION.

     1.12 "CUBIST INTELLECTUAL PROPERTY" means any and all knowledge, KNOW-HOW,
           ----------------------------                                        
          BIOLOGICAL MATERIALS, techniques, inventions, improvements and/or
          discoveries, whether or not patentable, copyrightable or subject to
          trademark protection and in whatever form kept, (i) which are
          conceived, created, originated and/or first reduced to practice
          pursuant to the COLLABORATION solely by CUBIST personnel or in which
          CUBIST has or acquires, pursuant to the COLLABORATION, ownership
          rights or a licensable interest that are or is not held jointly with
          MERCK and (ii) which are necessary or useful in discovering,
          developing, manufacturing, registering or marketing LICENSED PRODUCTS.

     1.13 "DRUG DEVELOPMENT PROGRAM" means that program *************
           ------------------------                                          
          for all pre-clinical and clinical development and regulatory
          filings leading to commercialization of ANTI-INFECTIVE AGENTS.

     1.14 "EFFECTIVE DATE" is June 13, 1996.
           --------------                   




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -6-
 
     1.15 "HIT" means any compound in the MERCK COMPOUND LIBRARY which, in the
           ---                                                                
          course of the PRIMARY SCREENING PROGRAM, is shown to meet the criteria
          for inhibitory activity against a PROGRAM tRNA SYNTHETASE, as such
          criteria is set forth in the RESEARCH PLAN.

     1.16 "IND" means an Investigational New Drug application filed with the
           ---                                                              
          United States Food and Drug Administration ("FDA"), or its equivalent
          or any corresponding application filed in any country other than the
          United States.

     1.17 "INTELLECTUAL PROPERTY" means, collectively, the MERCK INTELLECTUAL
           ---------------------                                             
          PROPERTY, CUBIST INTELLECTUAL PROPERTY, JOINT INTELLECTUAL PROPERTY,
          PATENT RIGHTS AND THIRD PARTY INTELLECTUAL PROPERTY.

     1.18 "JOINT INTELLECTUAL PROPERTY" means any and all knowledge, KNOW-HOW,
           ---------------------------                                        
          BIOLOGICAL MATERIALS, techniques, inventions, improvements and/or
          discoveries, whether or not patentable, copyrightable or subject to
          trademark protection and in whatever form kept, which are conceived,
          created, originated and/or first reduced to practice jointly by CUBIST
          and MERCK personnel pursuant to the COLLABORATION or in which, during
          the course of the 
<PAGE>
 
                                     -7-

          COLLABORATION, CUBIST and MERCK otherwise acquire joint ownership 
          rights pursuant to applicable provisions of U.S. law concerning rights
          of inventorship.

     1.19 "KNOW-HOW" means all information and data not generally known, (i)
           --------                                                         
          which are in the possession of or available to MERCK or CUBIST,
          currently or during the term of this Agreement and any future
          agreements regarding LICENSED PRODUCTS, or in which MERCK and/or
          CUBIST have ownership rights or a licensable interest, and (ii) which
          are necessary or useful in discovering, developing, manufacturing,
          registering or marketing LICENSED PRODUCTS.

     1.20 "LICENSE" shall have the meaning ascribed to it in Section 5.2.
           -------                                                       

     1.21 "LICENSED PRODUCT" means any product that contains a COMPOUND.
           ----------------                                             

     1.22 "MEDICINAL CHEMISTRY AND DRUG DISCOVERY PROGRAM" means that program
           ----------------------------------------------                    
          conducted for *************** the discovery and characterization of a
          SAFETY ASSESSMENT CANDIDATE.




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -8-
 
     1.23 "MEDICINAL CHEMISTRY NOTICE" shall have the meaning ascribed to it in
           --------------------------                                          
          Section 2.1.2.

     1.24 "MERCK" means MERCK & CO., INC. and its AFFILIATES.
           -----                                             

     1.25 "MERCK COMPOUND LIBRARY" OR "MERCK COMPOUNDS" means those chemical
           -------------------------------------------                      
          libraries or compounds owned or licensed by, or in the possession or
          control of, MERCK and composed of natural products, combinatorial
          chemistry libraries and synthetic sample collections.

     1.26 "MERCK CONFIDENTIAL INFORMATION" means all information which is
           ------------------------------                                
          disclosed by MERCK to CUBIST, either orally or in writing, in the
          course of the COLLABORATION to the extent that such information as of
          the date of disclosure to CUBIST is not (i) known to CUBIST (as
          evidenced in its records) other than by virtue of a prior confidential
          disclosure to CUBIST by MERCK; or (ii) disclosed in published
          literature, or otherwise generally known to the public through no
          fault or omission of CUBIST; or (iii) obtained from a third party free
          from any obligation of confidentiality to MERCK; or (iv) developed by
          CUBIST (as evidenced in writing) independent of the MERCK CONFIDENTIAL
          INFORMATION.
<PAGE>
 
                                     -9-
 
     1.27 "MERCK INTELLECTUAL PROPERTY" means any and all knowledge, KNOW-HOW,
          BIOLOGICAL MATERIALS, techniques, inventions, improvements and/or
          discoveries, whether or not patentable, copyrightable or subject to
          trademark protection and in whatever form kept, which are conceived,
          created, originated and/or first reduced to practice solely by MERCK
          personnel or in which MERCK has ownership rights or a licensable
          interest that are or is not held jointly with CUBIST.

     1.28 "NDA" means a New Drug Application filed with the United States FDA,
           ---                                                                
          or its equivalent or any corresponding application filed in any
          country other than the United States.

     1.29 "NET SALES" means the gross invoice price of LICENSED PRODUCT(S) sold
           ---------                                                           
          by MERCK or its sublicensees to an independent third party after
          deducting, if not already deducted in the amount invoiced:

          A.   *************************************************************
               **********************************************************
               *************************************

          B.   *********************************************************
               ******************************************************




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -10-
 
          C.   ************************************

          D.   ****************************************************************
               **************************************************************
               *******************************

     1.30 "PATENT CLAIM" means a claim of an unexpired patent or a patent
           ------------                                                 
          application included in the PATENT RIGHTS.

     1.31 "PATENT RIGHTS" means all U.S. provisional, non-provisional,
           -------------                                              
          continuation, continuation-in-part, divisional, reissue and re-
          examination patent applications claiming INTELLECTUAL PROPERTY; all
          patents issued from the aforementioned U.S. patent applications; and
          foreign patent applications, patents, patents of addition, inventor's
          certificates, utility models and other forms of protection granted or
          issued by foreign countries or regional authorities (e.g., European
          Patent Office) containing one or more claims which cover subject
          matter in the aforementioned U.S. patent applications.

     1.32 "PRIMARY AND SECONDARY SCREENING PROGRAM PAYMENT" means the payment
           --------------------------------------- -------                   
          set forth in Section 3.3 hereof.




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -11-
 
     1.33 "PRIMARY SCREENING MODULE PAYMENTS" means the payments set forth in
           ---------------------------------                                 
          Section 3.2 hereof.

     1.34 "PRIMARY SCREENING MODULES" means cloned, expressed, purified and
           -------------------------                                       
          active PROGRAM tRNA SYNTHETASES and the requisite methodologies and
          protocols sufficient to enable CUBIST and MERCK to perform the PRIMARY
          SCREENING PROGRAM.

     1.35 "PRIMARY SCREENING PROGRAM" means assays described as primary screens
           -------------------------                                           
          conducted at CUBIST and MERCK as set forth in the RESEARCH PLAN (as
          set forth in Exhibit 2).

     1.36 "PROGRAM tRNA SYNTHETASES" means ******************************
           ------------------------                                      
          ********************************************************************
          *******************************************************************
          *********************************************** to be used in the 
          PRIMARY SCREENING PROGRAM, subject to substitution pursuant to 
          Section 2.1.1(b)(iii)

     1.37 "RESEARCH COMMITTEE" shall have the meaning ascribed to it in Section
           ------------------                                                  
          2.2.

     1.38 "RESEARCH PLAN" means that plan set forth in Exhibit 2 containing the
           -------------                                                       
          PRIMARY SCREENING PROGRAM and the SECONDARY SCREENING PROGRAM, as such
          plan may be 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -12-
 
          modified or supplemented by the RESEARCH COMMITTEE pursuant to this 
          Agreement.

     1.39 "RESTRICTED COMPOUND" means ***************************************
           -------------------                                                
          *******************************************************************
          *******************************************************************
          *******************************************************************
          *******************************************************************

          
     1.40 "SAFETY ASSESSMENT CANDIDATE" means a compound with a scientific data
           ---------------------------                                         
          package that is evaluated and approved by the MERCK Research
          Management Committee for initiation of formal toxicology studies.

     1.41 "SECONDARY SCREENING PROGRAM" means assays described as secondary
           ---------------------------                                     
          screens and tertiary screens conducted at CUBIST and MERCK as set
          forth in the RESEARCH PLAN.

     1.42 "TECHNOLOGY ACCESS FEE" means the fee payment provided for in Section
           ---------------------                                               
          3.1 hereof.




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -13-
 
     1.43 "TERM" shall have the meaning ascribed to it in Section 11.1 of this
           ----                                                               
          Agreement.

     1.44 "THIRD PARTY INTELLECTUAL PROPERTY" means any and all knowledge,
           ---------------------------------                              
          KNOW-HOW, BIOLOGICAL MATERIALS, techniques, inventions, improvements,
          and/or discoveries, whether or not patentable, copyrightable or
          subject to trademark protection and in whatever form kept, which are
          conceived, created, originated and/or first reduced to practice by any
          third party or parties and are necessary or useful in discovering,
          developing, manufacturing, registering or marketing LICENSED PRODUCTS,
          and in which MERCK and/or CUBIST have a licensable interest.

     1.45 "UNIQUE COMPOUND" means, ********************************************
           ---------------                                               
          *********************************************************************
          *********************************************************************
          *********************************************************************
          *********************************************************************




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -14-
 
2.0  RESEARCH PLAN AND DRUG DEVELOPMENT PROGRAM

     2.1  Purpose. The objective of the RESEARCH PLAN, the MEDICINAL CHEMISTRY
          -------                                                             
          AND DRUG DISCOVERY PROGRAM and the DRUG DEVELOPMENT PROGRAM is to
          discover, develop and commercialize LICENSED PRODUCTS.

          2.1.1  The Screening Program.  The PRIMARY SCREENING PROGRAM and the
                 ---------------------                                        
                 SECONDARY SCREENING PROGRAM shall proceed as follows:

                 (a)  Production of Screening Modules No later than ************
                      after the EFFECTIVE DATE, CUBIST shall complete production
                      of the three PRIMARY SCREENING MODULES set forth in the
                      RESEARCH PLAN.

                 (b)  PRIMARY SCREENING PROGRAM

                      i)    Upon completion of the production of the three 
                            PRIMARY SCREENING MODULES, CUBIST and MERCK shall
                            employ these PRIMARY SCREENING MODULES in a PRIMARY
                            SCREENING PROGRAM to screen the MERCK COMPOUND
                            LIBRARIES in a manner which, in the sole judgment of
                            the RESEARCH




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<PAGE>
 
                                     -15-
 
                            COMMITTEE, is suitable for such purpose; provided,
                            however, that CUBIST shall have completed the
                            PRIMARY SCREENING PROGRAM to identify HITS, in a
                            diligent manner, no later than ************** after
                            CUBIST's receipt of each set of the MERCK COMPOUND
                            LIBRARIES. All such samples from the MERCK COMPOUND
                            LIBRARIES shall be provided to CUBIST in coded form.
                            It is understood that this timeline is based on
                            CUBIST performing up to ********* assays using the
                            MERCK COMPOUND LIBRARIES in the PRIMARY SCREENING
                            PROGRAM; therefore, if additional samples are
                            screened, the timeline will be reviewed and
                            additional agreed upon time will be granted to
                            CUBIST by MERCK.

                      ii)   ****************************************************
                            ****************************************************
                            ****************************************************
                            ****************************************************
                            ****************************************************




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<PAGE>
 
                                     -16-
 

                    iii)    During the PRIMARY RESEARCH PROGRAM, the RESEARCH
                            COMMITTEE of*************************************** 
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            ***************************************************
                            
                            




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<PAGE>
 
                                     -17-


                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  
                 ********************************************************  

                 (c)  SECONDARY SCREENING PROGRAM

                      i)    ************************************************ 
                            ********************************* CUBIST will begin
                            a 





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<PAGE>
 
                                     -18-
 
                            SECONDARY SCREENING PROGRAM with respect to such
                            HITS. The SECONDARY SCREENING PROGRAM will be
                            completed in a diligent manner, and, with respect to
                            each HIT, the results of such SECONDARY SCREENING
                            PROGRAM will be reported to MERCK ***************
                            *************************************************

                      ii)   **************************************************
                            **************************************************
                            **************************************************
                            **************************************************
                            **************************************************
    
                      iii)  It is understood that if during the course of
                            conducting the SECONDARY SCREENING PROGRAM, a HIT is
                            characterized that 




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<PAGE>
 
                                     -19-
 
                            the RESEARCH COMMITTEE has the option of selecting
                            that specific HIT to enter a MEDICINAL CHEMISTRY AND
                            DRUG DISCOVERY PROGRAM.

          2.1.2  The Medicinal Chemistry And Drug Discovery Program.  *******
                 --------------------------------------------------         
                 ************************************************************
                 ********************  the RESEARCH COMMITTEE shall promptly
                 designate a HIT or HITS which it recommends for further
                 evaluation as an ANTI-INFECTIVE AGENT or AGENTS in a MEDICINAL
                 CHEMISTRY AND DRUG DISCOVERY PROGRAM and shall notify CUBIST
                 and MERCK of such designation (the "MEDICINAL CHEMISTRY
                 NOTICE"). Subject to Sections 2.1.3(i) or 2.1.3(ii) hereof, as
                 applicable, CUBIST shall conduct the medicinal chemistry
                 activities during the course of the MEDICINAL CHEMISTRY AND
                 DRUG DISCOVERY PROGRAM. Subject to Section 2.1.3 and within
                 thirty (30) days of its receipt of the MEDICINAL CHEMISTRY
                 NOTICE, MERCK shall reveal to CUBIST the identity and chemical
                 structure of the HIT being developed, provided however, MERCK
                 shall not be obligated to make such disclosure if CUBIST
                 elects, pursuant to 2.1.3(i), not to pursue the MEDICINAL
                 CHEMISTRY AND DRUG DISCOVERY PROGRAM. 




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<PAGE>
 
                                     -20-

                 
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************







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<PAGE>
 
                                     -21-
        
        2.1.3  Party Responsible for the Medicinal Chemistry And Drug
               ------------------------------------------------------
               Discovery Program.
               ----------------- 

               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************
               *****************************************************************



 


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<PAGE>
 
                                     -22-
 
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************






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<PAGE>
 
                                     -23-
 
                 **************************************************************
                 **************************************************************
                 **************************************************************
                 **************************************************************
                 **************************************************************


          2.1.4  Drug Development Program.                                   
                 ------------------------                                    
                 **************************************************************
                 **************************************************************
                 **************************************************************
                 **************************************************************
                 **************************************************************






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<PAGE>
 
                                     -20-

                 ***********************************************************
                 ***********************************************************
                 ***********************************************************
                 ***********************************************************
                 ***********************************************************
                 ***********************************************************
                 ***********************************************************

     2.2  Research Committee.
          ------------------ 

          2.2.1  Purpose.  MERCK and CUBIST shall establish a RESEARCH COMMITTEE
                 -------                                                        
                 (the "RESEARCH COMMITTEE"):

                 (a)  to evaluate, recommend and modify scientific criteria to 
                      be implemented under the PRIMARY and SECONDARY SCREENING
                      PROGRAMS;

                 (b)  to prioritize HITS based on the PRIMARY SCREENING PROGRAM
                      and identify specific HITS to enter the SECONDARY 
                      SCREENING PROGRAM;

                 (c)  to evaluate data from the SECONDARY SCREENING PROGRAM and
                      make a recommendation to MERCK and CUBIST to initiate a
                      MEDICINAL CHEMISTRY AND DRUG DISCOVERY PROGRAM;




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                                     -25-
 
                 (d)  to review and evaluate progress under the PRIMARY and
                      SECONDARY SCREENING PROGRAMS; and

                 (e)  to prepare amendments to the PRIMARY and SECONDARY 
                      SCREENING PROGRAMS, as necessary.

          2.2.2  Membership.  MERCK and CUBIST each shall appoint, in its sole
                 ----------                                                   
                 discretion, three members to the RESEARCH COMMITTEE.
                 Substitutes for such appointees may be appointed at any time by
                 MERCK or CUBIST, as appropriate. The members initially shall
                 be:

                 MERCK Appointees: John Kozarich, James Heck and
                                  [_______]


                 CUBIST Appointees: Arthur F. Kluge, Philip Wendler
                                 and Susan Whoriskey


          2.2.3  Chair.  The RESEARCH COMMITTEE shall be chaired by two co-
                 -----                                                    
                 chairpersons, one appointed by MERCK and the other appointed by
                 CUBIST, each selected from the RESEARCH COMMITTEE membership.
<PAGE>
 
                                     -26-
 
          2.2.4  Meetings.  The RESEARCH COMMITTEE shall meet at such times and
                 --------                                                      
                 in such places as the parties deem appropriate, provided that
                 the RESEARCH COMMITTEE shall meet at least semi-annually until
                 the earlier of (a) the commencement of the DRUG DEVELOPMENT
                 PROGRAM or (b) the exercise by CUBIST of its election pursuant
                 to Section 2.1.3(i)(A). or 2.1.3(i)(B). Representatives of
                 MERCK or CUBIST or both, in addition to members of the RESEARCH
                 COMMITTEE, may attend such meetings at the invitation of either
                 party.

          2.2.5  Minutes.  The RESEARCH COMMITTEE shall keep accurate and
                 -------                                                 
                 complete minutes of its deliberations which record all proposed
                 decisions and all actions recommended or taken.  Drafts of the
                 minutes shall be prepared in accordance with such procedures as
                 the RESEARCH COMMITTEE shall determine, and copies of such
                 drafts shall be delivered to all RESEARCH COMMITTEE members.
                 Draft minutes shall be edited by the co-chairpersons and shall
                 be issued in final form only with the approval and agreement of
                 the co-chairpersons.

          2.2.6  Decisions. All decisions of the RESEARCH COMMITTEE shall be
                 ---------                                                  
                 made by a majority of the
<PAGE>
 
                                     -27-
 
                 members. In the event the RESEARCH COMMITTEE is unable to
                 achieve a majority with respect to any such decision, the
                 President of CUBIST, acting as a duly authorized representative
                 of CUBIST, and the Executive Vice President of Merck Research
                 Laboratories, acting as a duly authorized representative of
                 MERCK, shall discuss the matter and attempt, in good faith, to
                 reach agreement with respect to such decision. In the event
                 that the President of Cubist and the Executive Vice President
                 of Merck Research Laboratories shall be unable to reach
                 agreement, MERCK shall, in its sole discretion, make the final
                 decision.

          2.2.7  Expenses. MERCK and CUBIST shall each bear all expenses of
                 --------                                                  
                 their respective members related to their participation on the
                 RESEARCH COMMITTEE.

     2.3  Reports.  During the PRIMARY SCREENING PROGRAM, the SECONDARY
          -------                                                      
          SCREENING PROGRAM and the MEDICINAL CHEMISTRY AND DRUG DISCOVERY
          PROGRAM (but, in the case of the MEDICINAL CHEMISTRY AND DRUG
          DISCOVERY PROGRAM, only to the extent that CUBIST has not exercised
          its rights under Section 2.1.3(i) hereof), MERCK and CUBIST each shall
          furnish to the RESEARCH COMMITTEE summary written reports within
          fifteen (15) 
<PAGE>
 
                                     -28-
 
          days after the end of each quarter commencing on the
          EFFECTIVE DATE, which written reports shall provide all screening data
          and describe progress under the PRIMARY SCREENING PROGRAM, the
          SECONDARY SCREENING PROGRAM or the MEDICINAL CHEMISTRY AND DRUG
          DISCOVERY PROGRAM, as the case may be.

     2.4  Laboratory Facilities and Personnel.  CUBIST and MERCK each shall
          -----------------------------------                              
          provide suitable laboratory facilities, equipment and personnel for
          the work to be done in carrying out the PRIMARY SCREENING PROGRAM, the
          SECONDARY SCREENING PROGRAM and the MEDICINAL CHEMISTRY AND DRUG
          DISCOVERY PROGRAM.

     2.5  Diligent Efforts.  MERCK shall use reasonably diligent efforts,
          ----------------                                               
          consistent with its overall research, development and business
          objectives, to discover, develop and market LICENSED PRODUCTS in all
          countries where MERCK determines that it is commercially viable to do
          so.

     2.6  Biological Materials, Merck Compound Library And Information
          -------------------------------------------------------------

          2.6.1  All compounds provided by MERCK hereunder shall: (1) be
                 distributed only to CUBIST employees who have a need to receive
                 such compounds to carry out the 
<PAGE>
 
                                     -29
 
                 terms of this Agreement; (2) be used solely for purposes
                 expressly set forth in this Agreement; (3) be returned to MERCK
                 upon MERCK's request and (4) not be disclosed or distributed to
                 any third party without the prior written consent of MERCK.

          2.6.2  BIOLOGICAL MATERIALS transmitted to MERCK by CUBIST shall:  (1)
                 be distributed only to MERCK employees who have a need to
                 receive them to carry out the terms of this Agreement; (2) be
                 used solely for purposes expressly set forth in this Agreement;
                 (3) be returned promptly to CUBIST upon CUBIST's request and
                 (4) not be disclosed or distributed to any third party without
                 the prior written consent of CUBIST.

          2.6.3  Either party to this Agreement may use any information
                 generated by the other party in conducting research and/or
                 development pursuant to this Agreement for any purpose
                 expressly set forth in this Agreement, including the use in
                 obtaining or defending its patents.

3.0  PAYMENTS TO CUBIST

     3.1  Technology Access Fee.  Within thirty (30) days of the EFFECTIVE DATE,
          ---------------------                                                 
          MERCK will pay CUBIST the sum of
<PAGE>
 
                                     -30-
 
          ********** as a TECHNOLOGY ACCESS FEE to enter into this Agreement.
          The funds shall be wired to a bank account specified by CUBIST on the
          EFFECTIVE DATE.

     3.2  Primary Screening Module Payment.  Within thirty (30) days of the
          --------------------------------                                 
          EFFECTIVE DATE, MERCK will pay CUBIST ********** for the purpose of
          providing funding to CUBIST for providing and supplying the PRIMARY
          SCREENING MODULES.

     3.3. Primary and Secondary Screening Program Payment.  MERCK will pay
          -----------------------------------------------                 
          CUBIST *************** for the purpose of providing funding to CUBIST
          for conducting the PRIMARY AND SECONDARY SCREENING PROGRAMS.  It is
          understood that such payment is based on CUBIST conducting **********
          assays in the PRIMARY SCREENING PROGRAM.  Therefore, if MERCK elects
          to conduct or have conducted additional assays, the costs of such
          additional assays will be negotiated in good faith by the parties.
          All PRIMARY AND SECONDARY SCREENING PROGRAM PAYMENTS shall be paid by
          MERCK to CUBIST within thirty (30) days following MERCK's receipt of a
          quarterly invoice from CUBIST.

     3.4  Screening Program Milestones.  Subject to the limitations otherwise
          ----------------------------                                       
          set forth below in this Article 3, MERCK will pay 




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                                     -31-
 
          CUBIST ********** scientific milestone payment upon the successful
          completion of a SECONDARY SCREENING PROGRAM that yields a compound
          that satisfies the criteria outlined in the RESEARCH PLAN attached
          hereto as Exhibit 2. This *********** scientific milestone payment
                    ---------
          shall be payable only upon the initial achievement of such milestone
          and no amounts shall be due hereunder for subsequent or repeated
          achievement of such milestone. Any payments pursuant to this Section
          3.4 shall be wired to a bank account specified by CUBIST within thirty
          (30) days following MERCK's receipt of the SECONDARY SCREENING PROGRAM
          profiling results meeting the above-referenced scientific criteria.

     3.5  Drug Development Milestones and Royalties.  If the MEDICINAL CHEMISTRY
          -----------------------------------------                             
          AND DRUG DISCOVERY PROGRAM yields a SAFETY ASSESSMENT CANDIDATE which
          MERCK, in its sole discretion, determines to advance to a DRUG
          DEVELOPMENT PROGRAM, MERCK will make BASE MILESTONE PAYMENTS to CUBIST
          with respect to each milestone set forth in the table below
          ("MILESTONE"), as follows:

          i)     Compounds First to Achieve a Milestone.  With respect only to 
                 -------------------------------------- 
                 each COMPOUND that is the first COMPOUND to achieve a given
                 MILESTONE, MERCK shall pay to




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                                     -32-
 
                 CUBIST a BASE MILESTONE PAYMENT equal to ******************* of
                 the amount set forth in the table below (the "MILESTONE TABLE")
                 corresponding to such MILESTONE, *****************************
                 ******************************************

          ii)    Successor Compounds: The Second, Third and Fourth Compounds.
                 ----------------------------------------------------------- 

                 (a)  Second Compound. With respect to each COMPOUND that is the
                      ---------------                                           
                      second UNIQUE COMPOUND to achieve a given MILESTONE, MERCK
                      shall pay to CUBIST a BASE MILESTONE PAYMENT equal to
                      ************************** of the amount set forth in the
                      MILESTONE TABLE corresponding to such MILESTONE, ********
                      ******************************************************
                      ***********

                 (b)  Third Compound.  With respect to each COMPOUND that is the
                      --------------                                            
                      third UNIQUE COMPOUND to achieve a given MILESTONE, MERCK
                      shall pay to CUBIST a BASE MILESTONE PAYMENT equal to
                      ******************* of the amount set forth in the
                      MILESTONE TABLE corresponding to such 




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                                     -33-
 
                      MILESTONE, ***********************************************
                      **************************

                 (c)  Fourth Compound. With respect to each COMPOUND that is the
                      ---------------                                           
                      fourth UNIQUE COMPOUND to achieve a given MILESTONE, MERCK
                      shall pay to CUBIST a BASE MILESTONE PAYMENT equal to
                      ************************* of the amount set forth in the
                      MILESTONE TABLE corresponding to such MILESTONE, ********
                      *****************************************************
                      ***********


          iii)   No Other Base Milestone Payments. Except as expressly provided
                 --------------------------------                              
                in subsections (i) and (ii) of this Section 3.5, MERCK shall not
                be required to pay to CUBIST any BASE MILESTONE PAYMENTS for any
                COMPOUNDS that may achieve a MILESTONE.
 
 
                                MILESTONE TABLE

<TABLE> 
<CAPTION> 
                                                Base Milestone
                                                --------------
                     Milestone                    Payment ($)
                     ---------                    -----------
 
<S>                                       <C>
          Approval of SAFETY ASSESSMENT CANDIDATE
          by MERCK's Research Management                 *********
          Committee
 
          Initiation of Phase II Clinical Trials         *********

          Initiation of Phase III Clinical Trials        *********
</TABLE> 




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<PAGE>
 
                                     -34-
 
<TABLE> 
          <S>                                            <C> 
          Filing of NDA                                  *********

          Approval of NDA                                *********

</TABLE>

          All BASE MILESTONE PAYMENTS required to be made by MERCK under this
          Section 3.5 shall be made within thirty (30) days of MERCK's receipt
          of written notice of the achievement of a MILESTONE by the applicable
          COMPOUND.  MERCK shall be obligated to make the BASE MILESTONE
          PAYMENTS required under this Section 3.5 upon the achievement of a
          MILESTONE by the applicable COMPOUND, regardless of whether the
          development of such COMPOUND is discontinued at any time after the
          achievement of such MILESTONE.  Subject to Sections 3.6 and 3.7
          hereof, *************************************************************
          ********************************************************************
          *********************************************************************
          ******************* post-NDA approval in the United States.

          In addition to the BASE MILESTONE PAYMENTS that MERCK is required to
          make pursuant to the foregoing provisions of this Section 3.5, MERCK
          shall pay royalties to CUBIST for all LICENSED PRODUCTS, which
          royalties shall be equal to the sum of the worldwide annual NET SALES
          for all LICENSED PRODUCTS multiplied by the applicable royalty rate:




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<PAGE>
 
                                     -35-
 
<TABLE>
<CAPTION>
 
     Annual Net Sales (in millions) ("Tiers")  Percentage Of Net Sales
     ----------------------------------------  -----------------------
 
     <S>                                       <C>
               *********************           ***********************
               *********************           ***********************
               *********************           ***********************
</TABLE>

     3.6  **********************************************************************
          ----------------------------------------------------------------------
          ********************************************************************* 
          ----------------------                                        
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ***************************

     3.7  ********************************************************************* 
          -------------------------------------------------------------------
          ********************************************************************* 
          ----------------------                                            
          ***************************




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                                     -36-
 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 
          ********************************************************************* 


4.0  PAYMENTS OF ROYALTIES; ACCOUNTING FOR ROYALTIES; AND RECORDS

     4.1  Payment Term.  MERCK shall pay CUBIST a royalty based on the aggregate
          ------------                                                          
          NET SALES of all LICENSED PRODUCTS.  Such royalty shall be paid (as
          determined in Section 3.5 hereof), with respect to NET SALES in each
          country of the 




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<PAGE>
 
                                     -37-
 
          world where a LICENSED PRODUCT is sold, from the date of the first
          commercial sale (the date of the invoice of MERCK or a sublicensee of
          MERCK with respect to such sale) of such LICENSED PRODUCT in such
          country and continuing until the expiration of the term of the LICENSE
          with respect to such country pursuant to Section 5.3 hereof.

     4.2  Payment Dates.  Royalties shall be paid by MERCK on NET SALES within
          -------------                                                       
          forty-five (45) days after the end of each calendar quarter in which
          such NET SALES are made.  Such payments shall be accompanied by a
          statement showing all relevant sales information including the
          information employed to calculate NET SALES of each LICENSED PRODUCT
          by MERCK and every sublicensee of MERCK in each country, the
          applicable royalty rate for such LICENSED PRODUCT, and a calculation
          of the amount of royalty due.

     4.3  Accounting.  The NET SALES used for computing the royalties payable to
          ----------                                                            
          CUBIST by MERCK shall be computed and paid in U.S. dollars by wire or
          other mutually acceptable means.  ********************************
          ******************************************************************
          ******************************************************************
          ******************************************************************
          *********************************************************** 




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                                     -38-
 
          ******************************************************************
          **************

     4.4  Records.  MERCK shall keep for a period of three (3) years from the
          -------                                                            
          date of each payment of royalties complete and accurate records of
          sales and all other information necessary to calculate NET SALES of
          each LICENSED PRODUCT in sufficient detail to allow the accrued
          royalties to be determined accurately.  CUBIST shall have the right to
          cause an independent, certified public accountant to audit such
          records to confirm MERCK's or MERCK sublicensee's NET SALES and
          royalty payments for any year; provided, however, that such auditor
                                         --------  -------                   
          shall not disclose MERCK's CONFIDENTIAL INFORMATION to CUBIST.  Such
          audits may be exercised once a year, within three (3) years after the
          royalty period to which such records relate, upon notice from CUBIST
          to MERCK and during normal business hours.  CUBIST shall bear the full
          cost of such audit unless such audit discloses a variance of more than
          five percent (5%) from the amount of the NET SALES or royalties.  In
          such case, MERCK shall bear the full cost of such audit.  MERCK shall
          include in each sublicense granted by it pursuant to this Agreement a
          provision requiring the sublicensee to make reports to MERCK, to keep
          and maintain records of sales made pursuant to such sublicense and to
          grant access to such records by CUBIST's independent accountant to the
          same 




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<PAGE>
 
                                     -39-
 
          extent required by MERCK under this Agreement. Upon the expiration of
          three (3) years following the end of any year, the calculation of
          royalties payable with respect to such year shall be binding and
          conclusive upon CUBIST, and MERCK and its sublicensee shall be
          released from any liability or accountability with respect to
          royalties for such year. The terms of this Section 4.4 shall survive
          any termination or expiration of this Agreement for a period of three
          (3) years.

5.0  INTELLECTUAL PROPERTY RIGHTS AND MERCK LICENSE

     5.1  Ownership.  All CUBIST INTELLECTUAL PROPERTY shall be owned by CUBIST.
          ---------   
          All MERCK INTELLECTUAL PROPERTY shall be owned by MERCK.  All JOINT
          INTELLECTUAL PROPERTY shall be owned jointly by CUBIST and MERCK.  All
          rights of inventorship shall be determined in accordance with U.S.
          law.

     5.2  License Grant.  CUBIST grants to MERCK an exclusive, worldwide
          -------------                                                 
          royalty-bearing license, including the right to grant sublicenses, to
          make, have made, use, offer for sale, sell, have sold and import
          LICENSED PRODUCTS in the AREA under all of CUBIST's licensable rights
          in the INTELLECTUAL PROPERTY and PATENT RIGHTS (the "LICENSE").
<PAGE>
 
                                     -40-

     5.3  Term Of License Grant.  Unless terminated earlier pursuant to any
          ---------------------                                            
          provision set forth elsewhere in this Agreement, the LICENSE shall
          commence on the EFFECTIVE DATE and shall continue with respect to each
          LICENSED PRODUCT and each country of the world until the later of (i)
          the expiration date of the last to expire patents in such country that
          covers, in whole or in part, such LICENSED PRODUCT, (ii) the
          expiration date of the last to expire patents that covers, in whole or
          in part, such LICENSED PRODUCT in the country or countries of its
          manufacture or (iii) ************** following the date of the first
          commercial sale (the date of the invoice of MERCK or a sublicensee of
          MERCK with respect to such sale) of such LICENSED PRODUCT in such
          country.

     5.4  Merck Obligations With Respect to Sublicensees.  If MERCK grants one
          ----------------------------------------------                      
          or more sublicenses pursuant to the LICENSE, such sublicenses shall
          not have terms that are inconsistent with the term of this Agreement
          and the LICENSE.  Any such sublicense or sublicenses shall not relieve
          MERCK of its obligations pursuant to this Agreement.

     5.5  Rights with Respect to Aminoacyl- tRNA Synthetases.
          ---------------------------------------------------

          5.5.1  Subject to the provisions set forth below in Section 5.5.2,
                 CUBIST shall at all times retain all rights to the 




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<PAGE>
 
                                     -41-
 
                 PROGRAM tRNA SYNTHETASES (including, without limitation, the
                 right to use such PROGRAM tRNA SYNTHETASES in research
                 sponsored by CUBIST or any third party).

          5.5.2  CUBIST agrees that during the TERM, and in the AREA, CUBIST
                 **************************************************************
                 **************************************************************
                 **************************************************************
                 provided, however. that the restrictions imposed on CUBIST by
                 --------  -------
                 the foregoing provisions of this Section 5.5.2 shall terminate,
                 as to any PROGRAM tRNA SYNTHETASE, on the earlier of (i) the
                 date on which an NDA is filed with the FDA in connection with
                 any HIT with respect to such PROGRAM tRNA SYNTHETASE or in
                 connection with any analog of such HIT, or (ii) the date that
                 MERCK notifies CUBIST in writing that MERCK is abandoning its
                 programs relating to such PROGRAM tRNA SYNTHETASE.

          5.5.3  Notwithstanding anything expressed or implied in this Agreement
                 to the contrary, CUBIST retains the right at all times to
                 engage in a screening program sponsored by CUBIST or any third
                 party and, in connection therewith, to use the PROGRAM tRNA




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<PAGE>
 
                                     -42-
 
                 SYNTHETASES with non-MERCK compounds as long as such compounds
                 were initially identified through screening for inhibitors of
                 AMINOACYL-tRNA SYNTHETASES ***********************************
                 ************************************

6.0  LEGAL ACTION

     6.1  Actual or Threatened Disclosure or Infringement.  If information comes
          -----------------------------------------------                       
          to the attention of MERCK to the effect that any PATENT RIGHTS
          relating to a LICENSED PRODUCT are being, have been or are threatened
          to be infringed, MERCK shall have the right (but not the obligation)
          at its expense to take such action as it may deem necessary to
          prosecute or prevent such infringement, including the right to bring
          or defend any suit, action or proceeding involving any such
          infringement.  MERCK shall notify CUBIST promptly of the receipt of
          any such information and of the commencement of any such suit, action
          or proceeding.  If MERCK determines that it is necessary or desirable
          for CUBIST to join any such suit, action or proceeding, CUBIST shall,
          at MERCK's expense, execute all papers and perform such other acts as
          may be reasonably required to permit MERCK to act in CUBIST's name,
          and MERCK shall pay for any and all reasonable costs and expenses
          incurred by CUBIST in connection with such 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -43-
 
          litigation, including reasonable attorney's fees. If MERCK brings
          suit, it shall have the right first to reimburse itself out of any
          sums recovered in such suit or in its settlement for all reasonable
          costs and expenses, including reasonable attorney's fees paid, related
          to such suit or settlement, and ********************* of any funds
          that shall remain from said recovery shall be paid to CUBIST and the
          balance of such funds shall be retained by MERCK. If MERCK does not,
          within sixty (60) days after giving notice to CUBIST of the above-
          described information, bring suit against any infringer, CUBIST shall
          have the right to bring suit for such alleged infringement, but it
          shall not be obligated to do so. If CUBIST determines that it is
          necessary or desirable for MERCK to join any such suit, action or
          proceeding, MERCK shall, at CUBIST's expense, execute all papers and
          perform such other acts as may reasonably be required to permit CUBIST
          to act in MERCK's name, and CUBIST shall pay for any and all
          reasonable costs and expenses incurred by MERCK in connection with
          such litigation, including reasonable attorney's fees. If CUBIST
          brings suit, it shall have the right first to reimburse itself out of
          any sums recovered in such suit or in its settlement for all
          reasonable costs and expenses, including reasonable attorney's fees
          paid, related to such suit or settlement, and *************** of any
          funds that shall remain from said recovery shall be paid to MERCK and
          the balance of such funds shall be retained by 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -44-
 
          CUBIST. Each party shall always have the right to be represented by
          counsel of its own selection and at its own expense in any suit
          instituted by the other for infringement under the terms of this
          Section 6.1.

7.0  DEFENSE OF INFRINGEMENT CLAIMS

     CUBIST will cooperate with MERCK, at MERCK's expense, in the defense of any
     suit, action or proceeding against MERCK or any sublicensee of MERCK
     alleging an infringement of intellectual property rights of a third party
     by reason of the manufacture, use or sale of LICENSED PRODUCTS.  MERCK
     shall give CUBIST prompt written notice of the commencement of any such
     suit, action, or proceeding or claim of infringement and will furnish
     CUBIST a copy of each communication relating to the alleged infringement.
     CUBIST shall give to MERCK all authority (including the right to exclusive
     control of the defense of any such suit, action or proceeding and the
     exclusive right, after consultation with CUBIST, to compromise, litigate,
     settle or otherwise dispose of any such suit, action or proceeding),
     information and assistance necessary to defend or settle any such suit,
     action or proceeding; provided, however, MERCK shall obtain CUBIST's prior
     written consent to all or such part of any settlement which requires
     payment or other action by CUBIST or which may have a material adverse
     effect on CUBIST's business or income pursuant to this Agreement.  If the
     parties agree that CUBIST should join any suit, action or 
<PAGE>
 
                                     -45-
 
     proceeding pursuant to this Section, MERCK may, at MERCK's expense, join
     CUBIST as a defendant if necessary or desirable, in which event MERCK shall
     hold CUBIST free, clear and harmless from any and all costs and expenses of
     such litigation, including reasonable attorney's fees and CUBIST shall
     execute all documents and take all other actions, including giving
     testimony, which may reasonably be required in connection with the
     prosecution of such suit, action or proceeding.

8.0  TREATMENT OF CONFIDENTIAL INFORMATION

     8.1  Confidentiality
          ---------------

          8.1.1  MERCK and CUBIST each recognize that the other's Confidential
                 Information constitutes highly valuable, confidential
                 information. Subject to the terms and conditions of the
                 LICENSE, the obligations set forth in Section 8.3 and the
                 publication rights set forth in Section 8.2, MERCK and CUBIST
                 each agree that, during the TERM of this Agreement and for ****
                 ********* thereafter, it will keep confidential, and will cause
                 its AFFILIATES to keep confidential, all CONFIDENTIAL
                 INFORMATION that is disclosed to it or to any of its AFFILIATES
                 pursuant to this Agreement. Neither MERCK nor CUBIST nor any of
                 their respective AFFILIATES shall use such 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -46-
 
                 CONFIDENTIAL INFORMATION except as expressly permitted in this
                 Agreement.

          8.1.2  MERCK and CUBIST each agree that any disclosure of the other's
                 CONFIDENTIAL INFORMATION to any officer, employee or agent of,
                 or consultant to, the other party or of any of its AFFILIATES
                 shall be made only if and to the extent necessary to carry out
                 its responsibilities under this Agreement and shall be limited
                 to the maximum extent possible consistent with such
                 responsibilities. MERCK and CUBIST each agree not to disclose
                 the other's CONFIDENTIAL INFORMATION to any third parties under
                 any circumstance without the prior written permission from the
                 other party (which permission shall not be unreasonably
                 withheld or delayed if but only if any such disclosure shall be
                 required by applicable law). Each party shall take such action,
                 and shall cause its AFFILIATES to take such action, to preserve
                 the confidentiality of each other's CONFIDENTIAL INFORMATION as
                 it would customarily take to preserve the confidentiality of
                 its own CONFIDENTIAL INFORMATION. Each party, upon the other's
                 request, will return all the CONFIDENTIAL INFORMATION disclosed
                 to the other party pursuant to this Agreement, including all
                 copies and extracts of 
<PAGE>
 
                                     -47-
 
                 documents, within sixty (60) days of the request upon the
                 termination of this Agreement except for one (1) copy which may
                 be kept for the purpose of complying with continuing
                 obligations under this Agreement.

          8.1.3  CUBIST and MERCK each represent that all of its employees, and
                 any consultants to such party, participating in the
                 COLLABORATION, are bound by the obligations of confidentiality
                 set forth herein.

     8.2  Publication.  Notwithstanding any matter set forth with particularity
          -----------                                                          
          in this Agreement to the contrary, results obtained in the course of
          the COLLABORATION may be submitted for publication following
          scientific review and approval by MERCK and CUBIST, which approval
          shall not be unreasonably withheld, provided however, either party
          shall have the right to (a) propose modifications to the publication
          for patent, trade secret or business reasons, and/or (b) request a
          reasonable delay (not to exceed ninety (90) days) in publication or
          presentation in order to protect patentable information.  After
          receipt of the proposed publication by MERCK and CUBIST, written
          approval or disapproval shall be provided within thirty (30) days.

     8.3  Publicity.  Except as required by law and as provided below or in
          ---------                                                        
          Section 8.2 of this Agreement, neither party may 
<PAGE>
 
                                     -48-
 
          disclose the terms of this Agreement or the research described in it
          without the prior written consent of the other party, which consent
          shall not be unreasonably withheld. It is understood that the
          existence of this Agreement is anticipated to form the basis of a
          press release that will be released promptly following the EFFECTIVE
          DATE and that will be mutually satisfactory to the parties, provided
          that in no event shall such press release disclose the financial terms
          set forth in this Agreement.

     8.4  Disclosure of Inventions.  Each party shall promptly inform the other
          ------------------------                                             
          in writing about all inventions in the AREA that are conceived,
          actually reduced to practice or developed in the course of carrying
          out the COLLABORATION.

9.0  PROVISIONS CONCERNING THE FILING, PROSECUTION AND MAINTENANCE OF PATENT
     RIGHTS

     The following provisions relate to the filing, prosecution and maintenance
     of PATENT RIGHTS during the term of this Agreement:

     9.1  Filing, Prosecution and Maintenance of Patents Rights by Cubist.
          --------------------------------------------------------------- 

          Patent applications and granted patents naming CUBIST employees and/or
          consultants exclusively (the "CUBIST 
<PAGE>
 
                                     -49-
 
          PATENT RIGHTS") shall be filed, prosecuted and maintained by CUBIST.
          Patent applications and granted patents naming both MERCK and CUBIST
          employees and/or consultants (the "JOINT PATENT RIGHTS") shall also be
          filed, prosecuted and maintained by CUBIST, subject to the provisions
          set forth below. To the extent that CUBIST notifies MERCK in writing
          that CUBIST does not desire to continue filing, prosecuting and/or
          maintaining JOINT PATENT RIGHTS, CUBIST's obligation to continue to
          file, prosecute and/or maintain such JOINT PATENT RIGHTS shall
          terminate and MERCK shall have the right, exercisable in its sole
          discretion, to file, prosecute and maintain such JOINT PATENT RIGHTS.
          Patent applications and granted patents naming MERCK employees and/or
          consultants exclusively ("MERCK PATENT RIGHTS") shall be filed,
          prosecuted and maintained by MERCK.

          With respect to CUBIST PATENT RIGHTS and JOINT PATENT RIGHTS, CUBIST
          shall have the exclusive right:

          (a)    to file applications for letters patent on any invention
                 included in CUBIST PATENT RIGHTS and JOINT PATENT RIGHTS;
                 provided, however, that CUBIST shall consult with MERCK
                 regarding the content of such patent applications, as further
                 provided below, and regarding the countries in which such
                 patent 
<PAGE>
 
                                     -50-
 
                 applications should be filed and shall file patent applications
                 in those countries where MERCK requests that CUBIST file such
                 applications; and, further provided, that CUBIST, at its option
                 and expense, may file in countries where MERCK does not request
                 that CUBIST file such applications;

          (b)    to take all reasonable steps to prosecute all pending and new
                 patent applications included within CUBIST PATENT RIGHTS and
                 JOINT PATENT RIGHTS;

          (c)    to respond to oppositions, nullity actions, re-examinations,
                 revocation actions and similar proceedings filed by third
                 parties against the grant of letters patent for such
                 applications or against letters patent granted; and

          (d)    to maintain in force any letters patent included in CUBIST
                 PATENT RIGHTS and JOINT PATENT RIGHTS by duly filing all
                 necessary papers and paying any fees required by the patent
                 laws of the particular country in which such letters patent
                 were granted.

                 9.1.2  Review by Merck.  *************************************
                        ---------------                                        
                        *****************************************************
                        




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -51-

                        *******************************************************
                        *******************************************************
                        *******************************************************
                        *******************************************************

                 9.1.2  Copies of Documents.  CUBIST shall provide to MERCK 
                        -------------------
                        copies of all patent applications that are part of
                        CUBIST PATENT RIGHTS and JOINT PATENT RIGHTS, for the
                        purpose of obtaining substantive comment of MERCK's
                        patent counsel pursuant to Section 9.1.1 hereof. CUBIST
                        shall also provide to MERCK copies of all documents
                        relating to prosecution of all such patent applications
                        in a timely manner and shall 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -52-
 
                        provide MERCK every six (6) months a report detailing
                        their status.

                 9.1.3  Reimbursement of Costs for Filing, Prosecuting and
                        --------------------------------------------------
                        Maintaining PATENT RIGHTS.  Within thirty (30) days of
                        -------------------------                             
                        receipt of invoices from CUBIST, MERCK shall reimburse
                        CUBIST for ************************of all the costs
                        (including reasonable attorney's fees) incurred by
                        CUBIST in connection with preparing, filing,
                        prosecuting, responding to oppositions, nullity actions,
                        protests, reexaminations, revocation actions,
                        participating in interferences and similar proceedings
                        and maintaining patent applications and patents included
                        within CUBIST PATENT RIGHTS and JOINT PATENT RIGHTS, in
                        countries where MERCK requests that patent applications
                        be filed, prosecuted and maintained. Such reimbursement
                        shall be in addition to any other payments due CUBIST.
                        However, MERCK may, upon sixty (60) days notice, request
                        that CUBIST discontinue filing or prosecuting patent
                        applications in any country and discontinue reimbursing
                        CUBIST for the costs of filing, prosecuting, responding
                        to opposition or maintaining such patent application or
                        patent in 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -53-
 
                        any country. CUBIST shall pay all costs in those
                        countries in which MERCK does not request that CUBIST
                        file, prosecute or maintain patent applications and
                        patents, but in which CUBIST, at its option, elects to
                        do so.

                 9.1.4  MERCK shall have the right to file on behalf of and as 
                        an agent for CUBIST all applications and take all
                        actions necessary to obtain patent extensions pursuant
                        to 35 USC Section 156 and foreign counterparts for
                        CUBIST PATENT RIGHTS and JOINT PATENT RIGHTS described
                        in this Section 9.1 licensed to MERCK. CUBIST agrees to
                        sign, at MERCK's expense, such further documents and
                        take such further actions as may be requested by MERCK
                        in this regard.

     9.2  Filing, Prosecution and Maintenance of Patent Rights by MERCK.  With
          -------------------------------------------------------------       
          respect to MERCK PATENT RIGHTS, MERCK shall have those rights ascribed
          to CUBIST, and CUBIST shall have those rights and duties ascribed to
          MERCK, in Section 9.1 hereof; provided, however, that in no event
                                        --------  -------                  
          shall CUBIST have any of the obligations that MERCK has under Section
          9.1.3.
<PAGE>
 
                                     -54-
 
     9.3  Cooperation.  The parties agree to cooperate, to the extent
          -----------                                                
          practicable, with each other in connection with the preparation,
          prosecution, maintenance and defense of any patent applications and
          patents included in PATENT RIGHTS.

     9.4  Abandonment of Patent Rights.  The parties agree to notify each other
          ----------------------------                                         
          in a timely manner of any decision to abandon a pending patent
          application or an issued patent included in PATENT RIGHTS.
          Thereafter, the non-abandoning party shall have the option, at its own
          expense, to prosecute any such pending patent application or to keep
          the issued patent in force.

10.0 SOLE AGREEMENT

     This Agreement is the sole agreement with respect to the COLLABORATION and
     supersedes all other agreements and understandings between the parties with
     respect to same.

11.0 TERM, TERMINATION AND DISENGAGEMENT

     11.1  Term.  This Agreement shall become effective on the EFFECTIVE DATE
           ----                                                              
           and shall, unless earlier terminated by one of the parties in
           accordance with the terms of this Agreement, expire when MERCK is no
           longer obligated to pay 
<PAGE>
 
                                     -55-
 
           royalties to CUBIST in any country pursuant to this 
           Agreement (the "TERM").

     11.2  Termination. This Agreement may be terminated as follows:
           -----------                                              

          A.   Upon any material breach by either party under this Agreement,
               the non-breaching party may terminate this Agreement by giving
               ninety (90) calendar days prior written notice to the breaching
               party, specifying the material breach.  The termination shall
               become effective at the end of the ninety (90) calendar days.
               Notwithstanding any of the foregoing provisions of this Section
               11.2(A), if at any time during such ninety (90) calendar days,
               the breaching party cures any such material breach, then this
               Agreement shall not terminate but shall continue in full force
               and effect in accordance with its terms.

         B.    Notwithstanding any other provisions of this Agreement to the
               contrary, this Agreement may be terminated by either MERCK OR
               CUBIST, in its sole discretion, upon thirty (30) calendar days
               prior written notice to the other if (i) no HITS are identified
               pursuant to the PRIMARY SCREENING PROGRAM, (ii) no compound
               enters a MEDICINAL CHEMISTRY AND DRUG DISCOVERY PROGRAM pursuant
               to, and in accordance with, the provisions of this Agreement or
            
<PAGE>
 
                                     -56-
 
               (iii) no compound enters a DRUG DEVELOPMENT PROGRAM pursuant, and
               in accordance with, the provisions of this Agreement.  The
               parties hereby mutually agree that prior to either of them
               exercising the termination rights provided in this Section
               11.2(B), the parties shall discuss the proposed termination and
               the reasons therefor.

         C.    **************************************************************
               ***************************************************************
               **********************************************************
               *************************************************************
               ******************

     11.3  Rights Upon Termination.
           ----------------------- 

           11.3.1   If this Agreement is terminated by either MERCK or CUBIST
                    pursuant to Section 11.2(A), 11.2(B) or 11.2(C) hereof, as
                    applicable, then, on the effective date of such termination,
                    both parties' rights and obligations under this Agreement
                    shall terminate and be of no further force or effect
                    whatsoever, except to the extent otherwise provided in
                    Section 11.3.3, Section 




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -57-
 
                    11.3.4, Section 11.3.5, Section 11.3.6 or Section 11.3.7
                    hereof.

          11.3.2    Upon termination of this Agreement by CUBIST pursuant to
                    Section 11.2(A), upon termination of this Agreement by MERCK
                    or CUBIST pursuant to Section 11.2(B) or upon termination of
                    this Agreement by MERCK pursuant to Section 11.2(C), the
                    LICENSE shall automatically terminate with respect to all
                    countries of the world and all LICENSED PRODUCTS, effective
                    as of the effective date of the termination of this
                    Agreement.

          11.3.3    *********************************************************
                    ************************************************************
                    ************************************************************
                    **********************************************************
                    *********************************************************
                    ******************************************************  
                    ************************************************************
                    ********************************************************
                    **********************************************************
                    ****************




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -58-

            11.3.4  Neither the termination of this Agreement by either party
                    nor the expiration of the TERM shall terminate the
                    obligation of either party to make all payments accrued
                    prior to such termination or expiration. Neither the
                    termination of this Agreement by either party nor the
                    expiration of the TERM shall operate to release either party
                    from any liability arising from (i) such party's failure, at
                    any time prior to the effective date of such termination or
                    expiration, to perform or observe in any material respect
                    any term, covenant, representation, warranty, provision or
                    understanding contained in this Agreement or (ii) such
                    party's failure at any time (including, without limitation,
                    at any time after the termination of this Agreement or the
                    expiration of the TERM) to perform or observe in any
                    material respect any term, covenant, representation,
                    warranty, provision or understanding contained in this
                    Agreement and that, by its own terms, shall survive such
                    termination or expiration. Following any such termination or
                    expiration, each party shall be entitled to exercise any
                    remedies that are available, at law or in equity, to such
                    party
<PAGE>
 
                                     -59-
 
                    against the other party in connection with such other
                    party's failure to perform or observe in any material
                    respect any term, covenant, representation, warranty,
                    provision or understanding herein at any time prior to such
                    termination or expiration or, if and to the extent that such
                    term, covenant, representation, warranty, provision or
                    understanding survives such termination or expiration by the
                    express terms of any other provision of this Agreement, at
                    any time thereafter.

          11.3.5    The provisions of Section 2.6.1, Section 4.4, Section 5.1,
                    the first two sentences of Article 7, Section 8.1, Section
                    8.3, Section 11.3, Section 11.4, Article 13, Article 15 and
                    Section 16.10 shall survive the termination of this
                    Agreement.

          11.3.6    If this Agreement is terminated by either MERCK or CUBIST
                    pursuant to Section 11.2(B) or by MERCK pursuant to Section
                    11.2(C), CUBIST may request and MERCK, in its sole
                    discretion, may extend to CUBIST the opportunity to enter
                    into good faith negotiations to provide CUBIST the right to
                    (a) select one  or more compound(s) identified in the
                    SECONDARY 
<PAGE>
 
                                     -60-
 
                    SCREENING PROGRAM or the MEDICINAL CHEMISTRY AND
                    DRUG DISCOVERY PROGRAM for development by itself or with
                    third parties and (b) enter into a worldwide exclusive
                    license agreement under commercially reasonable terms.

     11.4  Dispute. Without in any way limiting the generality of the
           -------                                                    
           provisions of Section 16.10 hereof, the parties hereby agree that, in
           the event of a dispute between the parties as to whether a material
           breach has occurred under this Agreement entitling a party to
           exercise its right to terminate this Agreement pursuant to Section
           11.2(A), the dispute shall be resolved pursuant to the dispute
           resolution procedures set forth in 16.10 hereof.


12.0 REPRESENTATIONS AND WARRANTIES

     CUBIST and MERCK each represents and warrants as follows:

     12.1  It is a corporation duly organized, validly existing and is in good
           standing under the laws of its jurisdiction of incorporation, is
           qualified to do business and is in good standing as a foreign
           corporation in each jurisdiction in which the conduct of its business
           or the ownership of its properties 
<PAGE>
 
                                     -61-
 
           requires such qualification and has all requisite power and
           authority, corporate or otherwise, to conduct its business as now
           being conducted, to own, lease and operate its properties and to
           execute, deliver and perform this Agreement.

     12.2  The execution, delivery and performance by it of this Agreement have
           been duly authorized by all necessary corporate action and do not and
           will not (a) require any consent or approval of its stockholders, (b)
           violate any provision of any law, rule, regulations, order, writ,
           judgment, injunctions, decree, determination or award presently in
           effect having applicability to it or any provision of its certificate
           of incorporation or by-laws or (c) result in a breach of or
           constitute a default under any material agreement, mortgage, lease,
           license, permit or other instrument or obligation to which it is a
           party or by which it or its properties may be bound or affected.

     12.3  This Agreement is a legal, valid and binding obligation of it
           enforceable against it in accordance with its terms and conditions,
           except as such enforceability may be limited by applicable
           bankruptcy, insolvency, moratorium, reorganization or similar laws,
           from time to time in effect, affecting creditor's rights generally.
<PAGE>
 
                                     -62-
 
13.0 INDEMNIFICATION

     13.1  MERCK's Obligation to Indemnify.  MERCK will indemnify CUBIST for
           -------------------------------                                 
           damages, settlements and reasonable costs, legal fees and other
           expenses incurred in connection with any claim against CUBIST based
           on any action or omission of MERCK, its agents or employees related
           to the obligations of MERCK under this Agreement, excluding such
           damages, costs, legal fees and expenses arising from the negligence
           of CUBIST. MERCK, in its sole discretion, shall choose legal counsel,
           shall control the defense of such claim or action and shall have the
           right to settle same on such terms and conditions it deems advisable;
           provided however, it shall obtain CUBIST's prior written consent to
           all or such part of any settlement which requires payment or other
           action by CUBIST or which may have a material adverse effect on
           CUBIST's business or income pursuant to this Agreement. In the event
           of any product liability claim in connection with any LICENSED
           PRODUCT based in whole or in part upon any LICENSED PRODUCT made,
           sold, or distributed by MERCK, any AFFILIATE or any sublicensee of
           MERCK, MERCK will indemnify and hold CUBIST harmless against all
           damages, reasonable costs, reasonable expenses and reasonable
           attorneys' fees arising therefrom or connected therewith, excluding
           such damages, costs, expenses and attorneys' fees arising as a result
           of the negligence of CUBIST.
<PAGE>
 
                                     -63-
 
     13.2.  CUBIST's Obligation to Indemnify.  CUBIST will indemnify MERCK for
            --------------------------------                                  
            damages, settlements and reasonable costs, legal fees and other
            expenses incurred in connection with any claim against MERCK based
            on any action or omission of CUBIST, its agents or employees related
            to the obligations of CUBIST under this Agreement, excluding such
            damages, costs, expenses and attorneys' fees arising as a result of
            the negligence of MERCK. CUBIST, in its sole discretion, shall
            choose legal counsel, shall control the defense of such claim or
            action and shall have the right to settle same on such terms and
            conditions it deems advisable; provided however, it shall obtain
            MERCK's prior written consent to all or such part of any settlement
            which requires payment or other action by MERCK or which may have a
            material adverse effect on MERCK's business or income pursuant to
            this Agreement.

14.0 NOTICES

     All notices shall be in writing mailed via certified mail, return receipt
     requested, courier, or facsimile transmission addressed as follow, or to
     such other address as may be designated from time to time:

     If to MERCK:   To MERCK at its address as set forth at the beginning of
                    this Agreement.
                    Attention:    Patrick McDonald,
                                  Executive Director, Corporate
                                   Licensing
<PAGE>
 
                                     -64-
 
                    with copy to:  Office of the General Counsel.

     If to CUBIST:  To CUBIST at its address as set forth at the beginning of
                    this Agreement.
                    Attention:     Scott M. Rocklage, President
                    with copy to:  Justin P. Morreale
                                   Bingham, Dana & Gould
                                   150 Federal Street
                                   Boston, MA 02110-1726

     Notices shall be deemed given as of the date received.


15.0 GOVERNING LAW
     This Agreement shall be governed by and construed in accordance with the
     laws of the Commonwealth of Massachusetts.


16.0 MISCELLANEOUS

     16.1  Binding Effect.  This Agreement shall be binding upon and inure to
           --------------                                                    
           the benefit of the parties and their respective legal
           representatives, successors and permitted assigns.

     16.2  Headings.  Paragraph headings are inserted for convenience of
           --------                                                     
           reference only and do not form a part of this Agreement.

     16.3  Counterparts.  This Agreement may be executed simultaneously in two
           ------------                                                       
           or more counterparts, each of which shall be deemed an original.
<PAGE>
 
                                     -65-
 
     16.4  Amendment  and Waiver.  This Agreement may be amended, modified,
           ---------------------                                           
           superseded or canceled, and any of the terms may be waived, only by a
           written instrument executed by each party or, in the case of waiver,
           by the party or parties waiving compliance. The delay or failure of
           any party at any time or times to require performance of any
           provisions shall in no manner affect the rights at a later time to
           enforce the same. No waiver by any party of any condition or of the
           breach of any term contained in this Agreement, whether by conduct,
           or otherwise, in any one or more instances, shall be deemed to be, or
           considered as, a further or continuing waiver of any such condition
           or of the breach of such term or any other term of this Agreement.

     16.5  No Third Party Beneficiaries.  No third party including any employee
           ----------------------------                                        
           of any party to this Agreement, shall have or acquire any rights by
           reason of this Agreement. Nothing contained in this Agreement shall
           be deemed to constitute the parties partners with each other or any
           third party.

     16.6  Assignment and Successors.  This Agreement may not be assigned by
           -------------------------                                        
           either party without the prior written consent of the other party
           (which consent shall not be unreasonably withheld), except that each
           party may assign this Agreement and the rights and interests of such
           party, in whole or in part, 
<PAGE>
 
                                     -66-
 
           to any of its AFFILIATES, to any purchaser of the assets to which
           this Agreement relates or to any successor business resulting from
           any purchase, merger or consolidation of such party with or into such
           businesses.

     16.7  Force Majeure.  Neither MERCK nor CUBIST shall be liable for failure
           -------------                                                       
           of or delay in performing obligations set forth in this Agreement,
           and neither shall be deemed in breach of its obligations, if such
           failure or delay is due to natural disasters or any causes beyond the
           reasonable control of MERCK or CUBIST.

     16.8  Severability.  If any provision of this Agreement is or becomes
           ------------                                                   
           invalid or is ruled invalid by any court of competent jurisdiction or
           is deemed unenforceable, it is the intention of the parties that the
           remainder of the Agreement shall not be affected.

     16.9  Gender and Number,  Whenever the context may require, any pronouns
           -----------------                                                 
           used herein shall include the corresponding masculine, feminine or
           neuter forms, and the singular form of names, defined terms and
           pronouns shall include the plural and vice-versa.

     16.10 Dispute Resolution.  The parties agree to attempt initially to solve
           ------------------                                                  
           all claims, disputes, or controversies arising under, out 
<PAGE>
 
                                     -67-
 
           of, or in connection with this Agreement by conducting good faith
           negotiations. If the parties are unable to settle the matter between
           themselves, the matter shall thereafter be resolved by alternative
           dispute resolution (ADR), starting with mediation and including, if
           necessary, a final and binding arbitration in Boston, Massachusetts
           or at such other location as the parties may agree upon. The parties
           agree in the case of arbitration to select a single arbitrator who
           will establish the rules and procedures of the arbitration under the
           applicable Rules of the American Arbitration Association. In the
           event of an arbitration, the prevailing party shall be entitled to
           fees and expenses including attorney's fees.

     IN WITNESS WHEREOF, the parties have caused this Agreement to be executed
by their duly authorized representatives.


MERCK & CO., INC.


By
   -----------------------------


CUBIST PHARMACEUTICALS, INC.


By
   -----------------------------

<PAGE>
 
                                                                    EXHIBIT 10.9

                            Confidential Treatment
 
                 Collaborative Research and License Agreement



                                    between



                          Bristol-Myers Squibb Company



                                      and



                          Cubist Pharmaceuticals, Inc.
<PAGE>
 
                               TABLE OF CONTENTS



1.0  DEFINITIONS.....................................................

2.0  RESEARCH PLAN AND DRUG DEVELOPMENT
      PROGRAMS.......................................................
     2.1  Purpose....................................................
     2.2  Research Committee.........................................
     2.3  Reports....................................................
     2.4  Laboratory Facilities and Personnel........................
     2.5  Materials and Use of Information...........................

3.0  PAYMENTS TO CUBIST..............................................
     3.1  Equity Purchase............................................
     3.2  Research Funding...........................................
     3.3  Screening Program Milestones...............................
     3.4  Preclinical Lead Profile Milestones........................
     3.5  Drug Development Milestones................................
     3.6  Royalties..................................................
     3.7  Adjustments................................................
     3.8  Interest on Late Payments..................................

4.0  [INTENTIONALLY OMITTED].........................................
     5.1  License Rights.............................................
     5.2  Ownership Rights...........................................
     5.3  Sublicensing...............................................

6.0  PAYMENTS OF ROYALTIES, ACCOUNTING FOR
      ROYALTIES, RECORDS.............................................
     6.1  Payment Term...............................................
     6.2  Payment Dates..............................................
     6.3  Accounting.................................................
     6.4  Records....................................................

7.0  INFRINGEMENT BY THIRD PARTIES...................................
     7.1  Actual or Threatened Infringement of a
           Covered Product...........................................
     7.2  Actual or Threatened Infringement of a Cubist
           Patent Rights.............................................

8.0  DEFENSE OF INFRINGEMENT CLAIMS..................................
     8.1  Defense of Infringement Claims Pertaining
<PAGE>
 
                                     -ii-


           to Lead Compounds, Approved PLP
           Compounds, and Products...................................
     8.2  Defense of Infringement Claims Pertaining to
           Patent Rights Owned or Controlled by Cubist...............

9.0  TREATMENT OF CONFIDENTIAL INFORMATION...........................
     9.1  Confidentiality............................................
     9.2  Publication................................................
     9.3  Publicity..................................................

10.0 PROVISIONS CONCERNING THE FILING,
      PROSECUTION AND MAINTENANCE OF
      PATENT RIGHTS..................................................
     10.1 Inventions Pertaining to Primary Screening Modules.........
     10.2 Inventions Pertaining to Hits and Products.................

11.0 REPRESENTATIONS, WARRANTIES AND COVENANTS.......................
     11.1 Mutual Representations and Warranties......................
     11.2 Cubist Technology Representations and Warranties...........
     11.3 Mutual Indemnification.....................................
     11.4 BMS Product Indemnification................................
     11.5 Representations and Warranties of BMS......................

12.0 TERM AND TERMINATION............................................
     12.1 Term.......................................................
     12.2  Termination By Mutual Agreement...........................
     12.3 Termination for Cause......................................
     12.4 Termination upon Acquisition...............................
     12.5 Effect of Bankruptcy.......................................
     12.6 Effect of Expiration or Termination........................

13.0 DISPUTE RESOLUTION..............................................
     13.1 Disputes...................................................
     13.2 Dispute Resolution Procedures..............................

14.0 MISCELLANEOUS...................................................
     14.1 Assignment.................................................
     14.2 Binding Effect.............................................
     14.3 Force Majeure..............................................
     14.4 Notices....................................................
     14.5 Governing Law..............................................
     14.6 Waiver.....................................................
     14.7 Severability...............................................
     14.8 Independent Contractors....................................
<PAGE>
 
                                     -iii-


     14.9 Counterparts...............................................
     14.10  Entire Agreement.........................................
     14.11  No Third Party Beneficiaries.............................
<PAGE>
 
                                                       DRAFT DATED:  June 7,1996


                  COLLABORATIVE RESEARCH AND LICENSE AGREEMENT


     THIS AGREEMENT is entered into as of the Effective Date (as defined below)
by and between BRISTOL-MYERS SQUIBB COMPANY, a Delaware corporation having
offices at Route 206 at Province Line Road, P.O. Box 4000, Princeton, New Jersey
08543-4000 ("BMS"), and between CUBIST PHARMACEUTICALS, INC., a Delaware
corporation having an office at 24 Emily Street, Cambridge, MA 02139 ("Cubist").

                                    Recitals
                                    --------

     WHEREAS, Cubist has expertise in the biochemistry and molecular biology of
tRNA synthetases from microbial and human sources; and

     WHEREAS, Cubist has the scientific expertise and capacity to undertake the
alliance activities described below; and

     WHEREAS, BMS has the capability to undertake development of antimicrobial
agents and drug products for treatment of infectious diseases; and

     WHEREAS, BMS possesses a library of compounds and natural products, and is
capable of determining the enzyme inhibitory capability of samples taken from
such library versus Cubist's tRNA synthetase targets in a Primary Screening
Program (as defined below).

     NOW, THEREFORE, in consideration of the foregoing premises and of the
covenants, representations and agreements set forth below, the parties agree as
follows:

1.0  DEFINITIONS

     As used herein, the following terms shall have the following meanings:
"Affiliate" means, with respect to any Person, any other Person which directly
or indirectly controls, is controlled by, or is under common control with, such
Person.  A Person shall be regarded as in control of another Person if it/he/she
owns, or directly or indirectly controls, fifty percent (50%) or more of the
voting securities (or comparable equity interests) or other ownership interests
of the other Person, or if it/he/she directly or indirectly possesses the power
to direct or cause the direction of the management or policies of the other
Person, whether through the

                                      -5-
<PAGE>
 
                                      -2-


 ownership of voting securities, by contract or any other means whatsoever.

     "Agreement" means this agreement, together with all appendices, exhibits
and schedules hereto, and as the same may be amended or supplemented from time
to time hereafter by a written agreement duly executed by authorized
representatives of each party hereto.

     "Alliance" is the collaboration to be conducted by BMS and Cubist pursuant
to this Agreement.  Exhibit 1.1 hereto sets forth a diagram outlining the
Alliance.

     "Aminoacyl-tRNA Synthetases means those enzymes responsible for the
aminoacylation of tRNA molecules with their cognate amino acids.

     "Area" means research or development of compounds or agents having
Inhibitory Activity useful in the treatment, prevention, or management of
disease states in human beings.

     "Biological Materials" shall mean any material having a biological
activity, including, but not limited to, structural genes, genetic sequences,
promoters, enhancers, probes, linkage probes, vectors, plasmids, transformed
cell lines, transgenic animals, proteins and fragments thereof, peptides,
biological modifiers, antigens, antibodies, cell lines, antagonists, agonists,
inhibitors and other biologically active materials.

     "BMS Materials Library" means the sample collection library owned or
Controlled by BMS and which comprises synthetic and semi-synthetic compounds and
pure and mixed natural products.

     "BMS Test Materials" means samples selected by BMS from its Materials
Library.

     "commercially reasonable and diligent efforts" of a party will mean those
efforts consistent with the exercise of prudent scientific and business judgment
as applied to other research efforts and products of similar scientific and
commercial potential within the research programs and relevant product lines of
such party.

     "Confidential Information" means all information, compounds, data, and
materials received by either party from the other party pursuant to this
Agreement and all information, compounds, data, and materials developed in the
course of the Collaboration, including, without limitation, Know-How and
Technology of each party, subject to the exceptions set forth in Article 9.
<PAGE>
 
                                      -3-


     "Contract Period" means the period beginning on the Effective Date and
ending on the date on which this Agreement terminates.

     "Control" means possession of the ability to grant a license or sublicense
or to provide Biological Materials, as provided for herein, without violating
the terms of any agreement with any Third Party.

     "Covered Product" means a product approved for marketing in a country for
the diagnosis, treatment or prevention of human disease indications and:

     (i) which has Inhibitory Activity against an Aminoacyl-tRNA Synthetase,
     provided that the active substance in such product (or, if such active
     substance is an analog of the original active substance in such product,
     then such original active substance) shall not have been identified by, or
     was not known to, BMS or any of its Affiliates or funded research
     collaborators, and was not generally known to the public, as possessing
     Inhibitory Activity against such Aminoacyl-tRNA Synthetase prior to the
     date that such active substance was first identified as having Inhibitory
     Activity against an Aminoacyl-tRNA Synthetase by reason of the Primary
     and/or Secondary Screening Programs conducted by a party under this
     Agreement; and

     (ii) for which the right to make, have made, use or sell such product or
     the active substance in such product has not been licensed to BMS or its
     Affiliates by a Third Party (A) who had identified or ascertained,
     independently of any activity conducted by BMS or Cubist pursuant to this
     Agreement, that the active substance in such product (or, if such active
     substance is an analog of another active substance in such product provided
     by such Third Party, then such original active substance) possessed
     significant Inhibitory Activity against an Aminoacyl-tRNA Synthetase for
     which such substance or product is targeted, and (B) who had identified or
     ascertained same prior to the date that said active substance was first
     identified as having Inhibitory Activity against an Aminoacyl-tRNA
     Synthetase by reason of the Primary and/or Secondary Screening Programs
     conducted by a party under this Agreement; and

     (iii)  is not an approved PLP compound or marketed drug 4s of the Effective
     Date.

     "Cubist Patent Rights" means all Patent Rights pertaining to an Invention
which are owned by or come under the Control of Cubist or its
<PAGE>
 
                                      -4-


Affiliates, which Invention is conceived or reduced to practice at any time
prior to the termination of this Agreement, and which Invention is necessary or
useful to the performance by BMS of its duties under the Research Plan and Drug
Development Program or to the full exercise of the rights and benefits accorded
BMS under this Agreement.

     "Cubist Technology" means Technology that is owned by or comes under the
Control of Cubist or any of its Affiliates at any time prior to the end of the
termination of this Agreement, and which is necessary or useful to the
performance by BMS of its duties under the Research Plan and Drug Development
Program or to the full exercise of the rights and benefits accorded BMS under
this Agreement.

     "Drug Development Program" means that program conducted by BMS at its cost
and discretion for all pre-clinical and clinical development, regulatory
filings, and commercialization of an Approved PLP Compound.

     "Effective Date" means the date that this Agreement shall have been
executed by both parties and delivered to each other.

     "...exclusive...." means, with respect to the grant of a license or
sublicense, or to the appointment of a distributor, a license, sublicense, or
appointment whereby the licensee's, sublicensee's or appointee's rights are sole
and entire, and, except as set forth in this Agreement, operates to exclude all
others, including the licensor, sublicensor and appointor (except as expressly
provided in this Agreement), as the case may be, and may be exercised by the
licensee or through one or more of its Affiliates, but may be sublicensed to
Third Parties only as expressly permitted herein.

     "FDA" shall mean the United States Food and Drug Administration, or any
successor agency having regulatory jurisdiction over the manufacture,
distribution and sale of drugs in the United States.

     "Field" means the use of a Hit, Lead Compound, Approved PLP Compound or
Product in the research, testing, prevention, diagnosis and treatment of human
disorders, diseases, and conditions.

     "First Commercial Sale" of a Covered Product shall mean the first
commercial sale for use or consumption of such Covered Product in a country
after required marketing and, if applicable, pricing approval has been granted
by the applicable regulatory authority(ies) of such country.

     "Hit" means any BMS Test Material which, in the course of the Primary
Screening Program: (A) is shown to meet certain threshold
<PAGE>
 
                                      -5-


criteria for Inhibitory Activity, said criteria to be set forth in or determined
in the manner provided for in the Research Plan or as determined, changed, or
supplemented hereafter by the Research Committee from time to time in writing,
or (B) although not meeting all such threshold criteria, is determined by BMS in
good faith to have demonstrated a documented level of Inhibitory Activity
sufficient to warrant further Secondary Screening and/or development as a Lead
Compound hereunder.

     "IND" means an Investigational New Drug application filed with the United
States Food and Drug Administration ("FDA"), or its equivalent or any
corresponding application filed in any country other than the United States.

     "Inhibitory Activity" means, with respect to the active compound in a BMS
Test Material or an analog of such compound (or with respect to any compound of
a Third Party where a provision of this Agreement, by its intent or meaning, so
references the Inhibitory Activity of same), such compound's principal method of
action as a direct antagonist or agonist against a Program tRNA Synthetase, or
if discovered in a Secondary Screening Program to have such activity, as a
direct antagonist or agonist against a non-Program tRNA Synthetase, as the case
may be.

     "Invention" means any new and useful process, machine, manufacture, or
composition of matter.

     "Know-How" means all information and data which is not generally known to
the public, including without limitation, information and data pertaining to or
comprising: materials and chemicals, inventions, techniques, practices,
machinery and equipment, reagents, processes, methods, knowledge, know-how,
skill, experience, preclinical. and clinical data (including pharmacological and
toxicological test data), analytical and quality control data, patent
application data or descriptions, and marketing, sales and manufacturing data.

     "Lead Compound" has the meaning set forth in section 2.1.2.

     "Lead Compound Development Program" means that program, conducted by or
through BMS in accordance with this Agreement, for the further characterization
and pre-clinical development of a Lead Compound and where formal assignment of
chemistry resources for a fully integrated discovery program have been assigned
to such Lead Compound as reflected in the minutes of the meetings of the BMS
Drug Development Management Committee ("DDMC").  The Lead Compound Development
Program shall continue until such time as any such Lead Compound is
<PAGE>
 
                                      -6-

approved as an Approved PLP Compound or its further development is terminated or
abandoned by BMS.

     "NDA" means a New Drug Application or Product License Application, as
appropriate, and all supplements filed pursuant to the requirements of the FDA,
including all documents, data and other information concerning Covered Products
which are necessary for full FDA approval to market a Covered Product, or the
equivalent in any other country.

     "Net Sales" of a Covered Product shall mean the invoiced sales price of the
Covered Product billed by BMS or its Affiliates (or, where applicable, by
licensees of BMS) to customers of BMS (or its licensees) who are not Affiliates,
less (to the extent incurred and absorbed by BMS, its Affiliates, or any such
licensee): *********************************************************************
********************************************************************************
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********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
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********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
***




                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -7-


*********  Sales by BMS to an Affiliate or licensee shall constitute a sale
for purposes of this definition if the Affiliate or licensee is the end user of
the Covered Product.  Notwithstanding the foregoing, any Covered Products used
(but not sold for consideration) for promotional or advertising purposes or used
for clinical or other research purposes shall not be considered Net Sales
hereunder.

     
     ***************************************************************************
***********************************************************************
*****************************************************************************
********************************************************************************
*****************************************************************************
*******************************************************************************
********************************************************************************
****************************************************************************
****************************************************************************
**************************************************************************
**********************************************************************
****************************************************************************
*****************************************************************************
**************************************************************************
***************************************************************************
*****************************************************************************
*****************************************************************************
*******************************************************************************
******************************************************************************
****************************************************************************
************************************************************************
***********************************************

     "Patent Rights" means all U.S. or foreign (including regional authorities
such as the European Patent Office) regular or provisional patent applications,
including any continuation, continuation-in-part, or division thereof or any
substitute application therefor or equivalent thereof, and any patent issuing
thereon, including any reissue, reexamination or extension thereof and any
confirmation patent or registration patent or patent of additions based on any
such patent, containing one or more claims to an Invention (and in the case of
an issued patent, containing one or more Valid Claims), and which a party hereto
owns or Controls, individually or jointly, any title thereto or rights
thereunder.





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                      -8-


     "Person" shall mean an individual, corporation, partnership, limited
liability company, trust, business trust, association, joint stock company,
joint venture, pool, syndicate, sole proprietorship, unincorporated
organization, governmental authority, or any other form of entity not
specifically listed herein.

     "PLP" means a data package, termed a Preclinical Lead Profile, that
describes a particular Lead Compound and is presented to the BMS Pharmaceutical
Group Operating Committee ("BMSPGOC") in accordance with its procedures,
approval of which is necessary for such Lead Compound to be put on a development
track.  The data package will typically contain, without limitation,
(i) synthesis and physico-chemical properties of the compound, (ii) in vitro
activity, (ii) in vivo activity in appropriate animal models, (iv) metabolism,
absorption and pharmacokinetics data, (v) limited toxicology data, (vi) summary
of competition, (vii) patent status, and (viii) business plans for the product.
The candidate Lead Compound covered by the PLP becomes an "Approved PLP
Compound" when the approval by the BMSPGOC of the PLP candidate Lead Compound
has been documented in the BMSPGOC meeting minutes.

     "Primary Screening Modules" means cloned, expressed, purified and active
PSM-Program tRNA Synthetases and the requisite methodologies and protocols, as
well as all materials and reagents required to carry out same (including
specifications for the purity and stability of the enzymes for reagents supplied
and, if available, reaction kinetics where the reaction is in its linear range),
sufficient to enable BMS to perform not less than I million assays for each PSM-
Program tRNA Synthetase in a Primary Screening Program using BMS Test Materials.
A Primary Screening Module must be usable in high throughput screens by BMS in
accordance with its customary requirements, such requirements being previously
communicated by BMS to Cubist.

     "Primary Screening Program" means assays described as primary screens
conducted at BMS using BMS Test Materials for purposes of determining Inhibitory
Activity against the PSM-Program tRNA Synthetases, as set forth in the Research
Plan (and as more fully described in Exhibit 1.2).

     "Product" means any final form or dosage of any drug product that
incorporates a Lead Compound and that will be sold or used within the Field.

     "Product Invention Rights" has the meaning in section 5.2.3.
<PAGE>
 
                                      -9-


     "Program tRNA Synthetases" mean ******************************************
**** *******************************************************************
******************************************************************************
******************************************.  The specific Program tRNA
Synthetases may be changed or supplemented, pursuant to, and in accordance with
the provisions of, section 2.1.1(a) hereof The Program tRNA Synthetases which
will be used in preparing the Primary Screening Modules to be provided by to BMS
under section 2.1.1(a) hereof shall be ******************************
*************************************************************************
***************************************************************************,
****************************************************************************
************************************************ (hereinafter referred to as the
"PSM-Program tRNA Synthetases").  The specific PSM-Program tRNA Synthetases may
be changed or supplemented, pursuant to, and in accordance with the provisions
of, section 2.1.1(a) hereof

     "Research Committee" shall have the meaning ascribed to it in Section 2.2.

     "Research Plan" means that plan set forth in Exhibit 1.2 containing the
Primary Screening Program and the Secondary Screening Program, as such plan may
be supplemented or more fully described by the provisions of this Agreement.

     "Research Term" means the period commencing on the Effective Date and
ending on the third anniversary of the Effective Date, subject to extension by
mutual agreement or at BMS' election as provided for in Section 3.2 and subject
to early termination as herein provided.

     "Royalty Term" means, in the case of any Covered Product and as to any
country, the period of time commencing on the First Commercial Sale in such
country and ending upon the later of (i) the date that there no longer exists a
Valid Claim owned or controlled by BMS or its Affiliates covering the
manufacture, use or sale of such Covered Product in such country, or (ii) the
tenth (10th) anniversary of the date of First Commercial Sale of the Covered
Product in such country.

     "Secondary Screening Program" means assays described as secondary screens
and tertiary screens (IC\\50\\, selectivity, Aminoacyl-tRNA Synthetase spectrum,
mechanism of action, etc.) conducted by or through Cubist as set forth herein
(and as more fully described in the Research Plan).





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -10-


     "Technology" means and includes all inventions, materials (including
Biological Materials, chemicals or compounds), technology, technical
information., Know-How, expertise and trade secrets relating to the Area.

     "Territory" means all countries of the world.

     "Third Party" means any entity other than (i) Cubist or BMS, or (ii) any of
their Affiliates.

     "Valid Claim" means: (a) an issued claim under an issued Patent, which has
not (i) expired or been canceled, (ii) been declared invalid by an unreversed
and unappealable decision of a court or other appropriate body of competent
jurisdiction, (iii) been admitted to be invalid or unenforceable through
reissue, disclaimer or otherwise, and/or (iv) been abandoned in accordance with
or as permitted by the terms of this Agreement or by mutual written agreement;
or (b) a claim included in a pending Patent application that is being actively
prosecuted in accordance with this Agreement and which has not been (v)
canceled, (vi) withdrawn from consideration, (vii) finally determined to be
unallowable by the applicable governmental authority for whatever reason (and
from which no appeal is or can be taken), and/or (viii) abandoned in accordance
with or as permitted by the terms of this Agreement or by mutual written
consent.

2.0  RESEARCH PLAN AND DRUG DEVELOPMENT PROGRAMS

2.1  Purpose.  Cubist and BMS shall conduct the Research Plan, the Lead
     -------                                                           
     Compound Development Program and the Drug Development Program, subject to
     the terms and conditions of this Agreement, as follows:

     2.1.1  The Screening Program.  The screening program shall proceed as
            ---------------------                                         
            follows:

     (a)    Delivery of Screening Modules

            (i) Subject to and upon the delivery terms set forth below, Cubist
            will deliver the Primary Screening Modules to BMS. *** of the
            Primary Screening Modules will be delivered by Cubist no later than
            **************** after the Effective Date, an additional *** Primary
            Screening Modules will be delivered by Cubist no later than ***
            ************************* after the Effective Date and the remaining
            *** Primary Screening Modules will be delivered by Cubist no later
            than





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -11-


     ****************************** after the Effective Date. BMS will
     communicate to Cubist in a timely fashion any particular requirements BMS
     may have in order for Cubist to develop appropriate Primary Screening
     Modules tailored to BMS' needs.

     All such Primary Screening Modules must be reasonably acceptable to BMS.
     Promptly following receipt of each such Primary Screening Module, BMS will
     test same for acceptability in terms of effectiveness, accuracy,
     reliability, conformity to specifications, and usefulness in high
     throughput screening. BMS shall notify Cubist in writing as to whether BMS
     accepts each such Primary Screening Module within 60 days after receipt by
     BMS (and if not, BMS will provide Cubist with a list of the deficiencies
     found by BMS so that Cubist may develop an acceptable Module). Cubist will
     remedy such deficiencies and provide an acceptable Module within 60 days
     thereafter.

     If Cubist is unable to develop an acceptable Primary Screening Module for a
     PSM-Program tRNA Synthetase, then BMS shall have the right to select and
     substitute another Aminoacyl-tRNA Synthetase from those non-Program tRNA
     Synthetases that are not then the subject of an agreement between Cubist
     and a Third Party that precludes same. The non-Program tRNA Synthetase so
     selected by BMS shall thereafter replace said PSM-Program tRNA Synthetase
     and be treated as a PSM-Program tRNA Synthetase for all purposes under this
     Agreement. Within 90 days following such selection, Cubist will deliver to
     BMS a Primary Screening Module based on said substitute non-Program tRNA
     Synthetase, subject to acceptance as herein provided.

     (ii) Subject to section 2.1.1(a)(iii), if at anytime during the period
     commencing on the date of acceptance of a Primary Screening Module by BMS
     and ending on the expiration date of the Research Term, any such Primary
     Screening Module for whatever reason loses its effectiveness or efficacy or
     is no longer biologically active, Cubist will replace same as promptlyas
     practicable at no additional cost to BMS (unless the replacement is
     required as a result of negligence on the part of BMS, in which event BMS
     will reimburse Cubist for its direct costs incurred to manufacture and
     supply same, plus ***).





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -12-


     (iii) In the event that at any time during the Research Term, or one year
     thereafter, BMS requires Primary Screening Modules to conduct more than *
     ******* assays for a PSM-Program tRNA Synthetase in a Primary Screening
     Program, Cubist will use commercially reasonable and diligent efforts to
     deliver same to BMS as promptly as practicable (but in any event within 90
     days after receipt of BMS' request), and BMS will reimburse Cubist for its
     direct costs to manufacture and supply same plus *************************.

     (iv) Improvements to a Primary Screening Module that may be made by Cubist
     following delivery to and acceptance by BMS of such Module shall be made
     available to BMS at no additional charge during the Research Term.

     (v) In the event that the parties, in their discretion, mutually agree that
     Cubist will develop and provide to BMS additional primhry screening
     module(s) for one or more additional Non-Program tRNA Synthetases, then
     such Non-Program tRNA Synthetase(s) shall become, and be treated for all
     purposes hereafter, as a PSM-Program tRNA Synthetase, and all references to
     a limit of six PSM-Program tRNA Synthetases shall be adjusted to reflect
     the addition of such new non-Program tRNA Synthetases to the list of PSM-
     Program tRNA Synthetases subject to this Agreement.

(b)  Primary Screening Program

     (i) Upon receipt of each Primary Screening Module, BMS will use
     commercially reasonable and diligent efforts to employ each such Module in
     a Primary Screening Program to screen such BMS Test Materials as BMS deems
     appropriate for such purpose. BMS will use commercially reasonable and
     diligent efforts in conducting the Primary Screening Program, and will send
     samples of all the Hits obtained therefrom to Cubist within a reasonable
     time (but not later than 60 days) after identification of such Hit. Cubist
     will hold and use all such samples provided by BMS subject to and in
     accordance with its obligations under section 2.5 and article 9 hereof.

     (ii) Without BMS' prior written consent, Cubist agrees that, during the
     Research Term, neither Cubist nor any of its Affiliates shall engage in any
     research or drug development activities involving the use of any Program
     tRNA Synthetase





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -13-


     for any primary screening purpose similar to the Primary Screening Program
     conducted by BMS, whether conducted with Cubist (or any such Affiliate's)
     own funds or whether conducted under contract or other arrangement with, on
     behalf of, or sponsored by any Third Party, or grant license rights to any
     Third Party in violation of the rights licensed to BMS hereunder. It is
     understood that, after the Research Term, Cubist and its Affiliates may
     engage in any or all of the activities prohibited during the Research Term
     by the preceding sentence, so long as any agreements entered by Cubist with
     a Third Party thereafter do not conflict with the remaining terms and
     conditions of this Agreement.

(c)  Secondary Screening Program

     Within ******* of receipt of a sample of any Hit, Cubist will begin a
     Secondary Screening Program as described in Exhibit 1.2 with respect to
     such Hit. Such Secondary Screening Program activities shall include the
     screening of Hits, Lead Compounds and Approved PLP Compounds against all
     eubacterial, fungal and human Aminoacyl-tRNA Synthetases. If, at the time
     that Cubist commences a Secondary Screening Program with respect to a Hit,
     Cubist does not then have one or more eubacterial, fungal or human
     Aminoacyl-tRNA Synthetases available for Secondary Screening, Cubist will
     perform such Secondary Screening for such Hit at such later data(s) within
     the Research Term (or as provided in section 2.1.1(c)(iii)) at BMS' request
     as and when such Secondary Screen becomes available to it.

     Cubist will use commercially reasonable and diligent efforts to conduct the
     Secondary Screening Program and will report the results to BMS no later
     than ************** after Cubist's receipt of a sample. During the course
     of the Secondary Screening Program conducted by Cubist on a Hit, BMS will
     use commercially reasonable and diligent efforts to perform such
     microbiological assays and animal studies as BMS may determine to perform
     in its sole discretion on any such Hit.

     (ii) Notwithstanding the rights exclusively licensed to BMS by Cubist
     pursuant to subparagraph (A) of section 5.1.1 hereof, Cubist retains the
     right at all times to use the Program tRNA Synthetases with non-BMS
     compounds in a secondary screening program conducted at Cubist (whether





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<PAGE>
 
                                     -14-


     sponsored by Cubist or by any Third Party) under the condition that such
     non-BMS compounds shall have been first identified as having inhibitory
     activity against a non-Program tRNA Synthetase in a primary screening
     program for inhibitors of such non-Program tRNA Synthetases and where the
     objective criteria under such primary screening program as to the compounds
     constituting a "hit" were substantially similar in terms of scientific
     threshold to those required for a Hit in the Primary Screening Program
     hereunder.

     (iii) At all times during the term of this Agreement, Cubist will use
     commercially reasonable and diligent efforts to perform such Secondary
     Screening Program activities (**************************************
     ************************************) as BMS may request on Hits, Lead
     Compounds and Approved PLP Compounds (and any analogs of any of the
     foregoing made by or for BMS); provided, however, that if Cubist is
     requested by BMS following the end of the Research Term to conduct any such
     Secondary Screening activities, BMS will reimburse Cubist quarterly in
     arrears for all direct costs incurred by Cubist to conduct such Secondary
     Screening Program activities, plus *************************.

     (iv) It is understood that if, during the course of conducting the
     Secondary Screening Program, the data so obtained reveals that a Hit has
     superior properties (such as IC\\50\\, selectivity, etc.) in targeting an
     Aminoacyl-tRNA Synthetase that is not a PSM-Program tRNA Synthetase, BMS
     has the option of selecting that specific Hit to enter a Lead Compound
     Development Program and to develop that Hit into a drug product that
     inhibits the activity of such Aminoacyl-tRNA Synthetase.

     (v) BMS will use reasonable efforts to notify Cubist promptly of any of
     compound or other substance identified by BMS as a Hit for which BMS
     intends to seek Secondary Screening Program services hereunder, but which
     BMS or its Affiliates had previously identified or knew as having
     Inhibitory Activity against an Aminoacyl-tRNA Synthetase.





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                                     -15-


(d)    Cubist Summary Report

       Cubist will report monthly to BMS in reasonable detail with respect to
       its activities by providing an updated copy of a report in the form
       attached as Exhibit 2.1.1(d) hereto.

2.1.2  The Lead Compound Development Program.  Based on the results of the
       -------------------------------------                              
       Secondary Screening Program for a Hit conducted by Cubist and the related
       research activities conducted by BMS under section 2.1.1(c)(i) in
       conjunction with such Secondary Screening Program, BMS will in its sole
       discretion determine which, if any, such Hit(s) will be approved as Lead
       Compounds and developed further in a Lead Compound Development Program
       conducted by BMS. BMS shall be responsible for all medicinal chemistry
       activities during the course of the Lead Compound Development Program for
       such Lead Compound, as well as following any approval of an Approved PLP
       Compound. At BMS' request and in accordance with section 2.1.1(c)(iii),
       Cubist will continue to run the biochemical assays outlined in the
       Secondary Screening Program portion of the Research Plan against analogs
       and other new chemical entities arising from the BMS medicinal chemistry
       program on such Lead Compound (and any Approved PLP Compound resulting
       from such Lead Compound Development Program). The conduct of the Lead
       Compound Development Program and all medicinal chemistry activities shall
       be solely within the control and discretion of BMS, and it is understood
       and agreed that BMS may in its discretion suspend or terminate, in whole
       or in part, the Lead Compound Development Program for a Lead Compound at
       any time. It is further understood that any analogs of a Hit or Lead
       Compound that BMS may make from time to time and which are approved for
       development under a Lead Compound Development Program shall also be
       considered "Lead Compounds" hereunder.

       BMS will report to Cubist on the progress of the discovery and
       development of any Lead Compound through the quarterly meetings of the
       Research Committee (annually after approval of an Approved PLP Compound
       by BMS). All such reports by BMS shall be treated as BMS Confidential
       Information hereunder.
<PAGE>
 
                                     -16-


       BMS will be responsible for all pre-clinical development, toxicology and
       clinical development, including all regulatory filings, of Hits, Lead
       Compounds, and Approved PLP Compounds arising out of this Agreement.

       In the event that BMS discontinues further development of a Hit (on which
       Cubist has completed all Secondary Screening Program activities
       hereunder), Lead Compound or Approved PLP Compound, BMS agrees to discuss
       with Cubist whether, and upon what terms, BMS might be willing to license
       rights in such compound to Cubist for further development so long as BMS
       is not then developing any competing compound; provided, however that BMS
       shall not be under any obligation, express or implied, to enter into or
       negotiate any such agreement.

2.1.3  PLP Approval and Product Development.  BMS shall have sole and
       ------------------------------------                          
       absolute discretion and control over the conduct of, and all activities
       associated with, the development or abandonment of any Lead Compound, the
       approval of a Lead Compound as an Approved PLP Compound, the development
       or abandonment of any Approved PLP Compound, all regulatory activities
       relating to the manufacture, use or sale of any Approved PLP Compound or
       Product, and the commercialization and marketing of any Product in any
       country. All INDs, NDAs and other regulatory filings made or filed by BMS
       for any Approved PLP Compound or Product shall be owned solely by BMS.
       BMS will provide annual summary reports to Cubist on the status of any
       Approved PLP Compound then in development. Other than royalty reports
       required hereunder, no reports shall be required of BMS with respect to
       any activities connected with the commercialization of any Covered
       Product approved for marketing in any country.

2.1.4  Ownership of Data.  All results and data generated by BMS in
       -----------------                                           
       connection with this Agreement, and all results and data generated by
       Cubist hereunder with respect to any Hits, Lead Compounds and Approved
       PLP Compounds (and analogs of any of the foregoing made and provided by
       BMS), shall be owned exclusively by BMS and shall be treated as BMS
       Confidential Information hereunder.
<PAGE>
 
                                     -17-


2.2  Research Committee.
     ------------------ 

     2.2.1  Purpose.  BMS and Cubist shall establish a Research Committee (the
            -------                                                           
            "Research Committee"):

            (a)  to evaluate and recommend scientific criteria to be implemented
                 under the Primary and Secondary Screening Programs;
            (b)  to make recommendations as to the prioritization of Hits based
                 on the Primary Screening Program and the specific Hits to enter
                 the Secondary Screening Program;
            (c)  to evaluate data from the Secondary Screening Program and make
                 a recommendation to BMS to initiate a Lead Compound Development
                 Program for a particular Hit;
            (d)  to review and evaluate progress under the Primary and Secondary
                 Screening Programs;
            (e)  to prepare amendments to the Primary and Secondary Screening
                 Programs; and
            (f)  to coordinate and monitor publication of research results
                 obtained from and the exchange of information and materials
                 that relate to the Alliance.
                 
     2.2.2  Membership.  BMS and Cubist each shall appoint, in its sole
            ----------                                                 
            discretion, three (3) members to the Research Committee. Substitutes
            may be appointed at any time.

     2.2.3  Chair.  The Research Committee shall be chaired by two co-
            -----                                                     
            chairpersons, one appointed by BMS and the other appointed by 
            Cubist.

     2.2.4  Meetings.  The Research Committee shall meet at least quarterly, at
            --------                                                           
            places selected by each party in turn and on a mutually acceptable
            date to the Chairpersons. Representatives of BMS or Cubist or both,
            in addition to members of the Research Committee, may attend such
            meetings at the invitation of either party. Meetings may also be
            called by either party on fifteen (15) days written notice to the
            other unless such notice is waived by the parties. The Research
            Committee may also convene or be polled or consulted from time to
            time by means of telecommunication or correspondence.

     2.2.5  Minutes.  The party designating the location for a meeting will
            -------                                                        
            appoint one of its members to serve as secretary for such 
<PAGE>
 
                                     -18-


            meeting and to take minutes of that meeting describing in reasonable
            detail the discussion had at that meeting and a list of any actions,
            decisions, or determinations approved by the Research Committee, and
            shall be responsible for circulation of the draft minutes. Draft
            minutes shall be edited by the co-chairpersons and shall be issued
            in final draft form sufficiently in advance of the next meeting to
            allow adequate review and comment prior to the meeting. Minutes of a
            meeting shall be approved or disapproved, and revised as necessary,
            at the next meeting.

     2.2.6  Decisions.  Subject to section 13.2.1, all decisions of the Research
            ---------                                                           
            Committee shall be made by a majority of the members.

     2.2.7  Expenses.  BMS and Cubist shall each bear all expenses of their
            --------                                                       
            respective members related to their participation on the Research 
            Committee.

2.3  Reports.  During the Contract Period, BMS and Cubist each shall
     -------                                                        
     furnish to the Research Committee:

     2.3.1  summary written reports within thirty (30) days after the end of
            each quarter commencing on the Effective Date, providing all
            screening data and describing progress under the Primary and
            Secondary Screening Programs, and

     2.3.2  comprehensive written reports within thirty (30) days after the end
            of each year, describing in detail the work accomplished by it under
            the Primary and Secondary Screening Programs, and discussing and
            evaluating the results of such work.

2.4  Laboratory Facilities and Personnel.  Cubist and BMS each shall
     -----------------------------------                            
     provide suitable and sufficient laboratory facilities, equipment and
     personnel for the work to be done in carrying out their obligations under
     this Agreement.

2.5  Materials and Use of Information
     --------------------------------

     2.5.1  Subject to articles 2.5.3, 5.1 and 5.3, each party shall retain all
            rights, title and interest to any and all Biological Materials,
            compounds or other substances created prior to or during the term of
            this Agreement by or for such party.
<PAGE>
 
                                     -19-


     2.5.2  Biological Materials, compounds and other substances transmitted to
            a party by the other shall: (1) be used solely for purposes
            consistent with this Agreement; and (2) not be distributed to any
            Third Party, other than employees, agents, consultants and
            contractors of the receiving party or its Affiliates who work at a
            facility owned or leased by the receiving party or its Affiliates,
            who have reason to receive them in order to assist the receiving
            party to screen, research, and develop any Hit, Lead Compound or
            Approved PLP Compound in accordance with such party's obligations
            under this Agreement, and who are bound by the terms of this
            Agreement in the same manner as the receiving party.

     2.5.3  With respect to any Hits, Lead Compounds or other compounds provided
            to Cubist by BMS, Cubist agrees not to make any derivatives,
            analogs, conjugates or other modifications from or with same
            (collectively, "Modifications"), and agrees, to the extent not
            already published, not to sequence, analyze or otherwise determine
            the chemical structure or physical properties of same. If Cubist
            does so in violation of the foregoing sentence, all such
            Modifications, and all rights, title and interests in and to same,
            shall belong exclusively to BMS.

     2.5.4  Subject to article 5 hereof, either party to this Agreement may use
            any information generated by the other party in conducting pre-
            clinical and clinical research and/or development pursuant to this
            Agreement for any purpose consistent with this Agreement, including
            the use in prosecuting or defending its patents and, in the case of
            BMS, use in marketing or obtaining regulatory approval for a product
            or in conducting pre-clinical and clinical studies.

3.0  PAYMENTS TO CUBIST

     3.1  Equity Purchase.  On the Effective Date, BMS and Cubist will execute
          a Stock Purchase Agreement, in the form set forth in Exhibit 3.1,
          providing for the purchase by BMS of shares of Cubist's capital stock
          for a total purchase price of $4,000,000.  Such aggregate purchase
          price shall be wired to a bank account specified by Cubist on the
          Effective Date.

     3.2  Research Funding.  BMS will pay to Cubist ********** per calendar
          year for ********* years (with an option at BMS' election for *
          ********** year at the same ********** level) (i) to support Cubist
          in





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                                     -20-


          making the Primary Screening Modules, in fulfilling its obligations
          under the Primary and Secondary Screening Programs during the term of
          this Agreement, and otherwise in fulfilling its obligations hereunder,
          and (ii) for any other research purpose that Cubist, in its sole
          discretion, deems necessary, so long as Cubist is able to fulfill its
          obligations under (i). Payments shall be wired to a bank account
          specified by Cubist. Each annual amount shall be payable in advance in
          four equal quarterly installments relating to each calendar quarter
          occurring during the Research Term. Payments will be made on or before
          January 15, April 15, July 15 and October 15 for the first, second,
          third and fourth calendar quarters, respectively. Any payment for a
          portion of a calendar quarter shall be made on a pro rata basis. The
          first such payment shall be made on the Effective Date. If BMS elects
          to proceed with ******** year, such option must be exercised, if at
          all, by BMS not later than 90 days prior to the end of the ***** year
          and shall be paid to Cubist in the same manner as payments during the
          first ***** years.

     3.3  Screening Program Milestones.  Subject to section 3.7:
          ----------------------------

          (a) Primary Screening Modules: BMS will pay Cubist *****************
              *************************** upon the delivery of each Primary
              Screening Module accepted by BMS pursuant to Section 2.1.1(a)(i).
              Payments shall be wired to a bank account specified by Cubist
              within thirty (30) days following such acceptance. Such payment
              shall be made only once with respect to a Primary Screening Module
              for each of the six (6) PSM-Program tRNA Synthetases (i.e., if
              Cubist develops and provides to BMS an improved Primary Screening
              Module for one previously accepted by BMS and for which BMS has
              already paid the ******** fee, BMS shall not be obligated to again
              pay such fee for such Module).

          (b) Lead Compound Development Program., Where, pursuant to section
              2.1.2, BMS has determined that a Hit should become a Lead Compound
              and enter a Lead Compound Development Program conducted by BMS,
              BMS will promptly notify Cubist of same and will pay to Cubist
              *********************************************** for each such Lead
              Compound; provided, however, that such payments will only be made
              once with respect to any specific Program tRNA Synthetase and only
              with respect to the first such Lead Compound that was identified
              in the Primary Screening Program as a Hit having Inhibitory
              Activity against such specific Program





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<PAGE>
 
                                     -21-


              tRNA Synthetase. Accordingly, no more than six (6) such payments
              in the aggregate may be made under this paragraph 3.3(b), and only
              one with respect to a particular Program tRNA Synthetase (i.e., if
              two Lead Compounds were both first identified in the Primary
              Screening Program as Hits having Inhibitory Activity against the
              same Program tRNA Synthetase, no ******** payment will be due on
              the second such Lead Compound). Payments shall be wired to a bank
              account specified by Cubist within thirty (30) days following
              BMS's determination that a Hit should become a Lead Compound and
              enter a Lead Compound Development Program.

     3.4  Preclinical Lead Profile Milestones. BMS will promptly notify Cubist
          -----------------------------------
          of each Approved PLP Compound approved for further development by the
          BMSPGOC. Subject to section 3.7 hereof, BMS will pay Cubist **********
          *********************************** for each Approved PLP Compound so
          approved for further development by the BMSPGOC; provided, however,
          that such payments will only be made once with respect to any specific
          Program tRNA Synthetase and only for the first such Approved PLP
          Compound that was identified in the Primary Screening Program as a Hit
          having Inhibitory Activity against such specific Program tRNA
          Synthetase. Accordingly, no more than six (6) such payments in the
          aggregate may be made under this paragraph 3.4, and only one with
          respect to a particular Program tRNA Synthetase (i.e., if two Approved
          PLP Compounds were both identified in the Primary Screening Program as
          Hits having Inhibitory Activity against the same Program tRNA
          Synthetase, no ******** payment will be due on the second such
          Approved PLP Compound). Payments shall be wired to a bank account
          specified by Cubist within thirty (30) days following such BMSPGOC
          approval.

     3.5  Drug Development Milestones. Subject to section 3.7 hereof, if an
          ---------------------------
          Approved PLP Compound should reach the following milestones, BMS will
          promptly notify Cubist of same and will pay the following amounts to
          Cubist:

<TABLE> 
<CAPTION> 
          Event                                                    Payment (US$)
          -----                                                    -------------
          <S>                                                      <C>
          Initiation of Phase II Clinical Trials in any country      *********
          Initiation of Phase III Clinical Trials in any country     *********
          Filing of NDA in the U.S., Japan, France, Germany,
               Great Britain, Italy, Spain or pursuant to the
</TABLE> 





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<PAGE>
 
                                     -22-


<TABLE> 
          <S>                                                      <C>  
               coordinated EMEA filing process                       *********
          Approval of NDA in the U.S., Japan, France, Germany,
               Great Britain, Italy, Spain or pursuant to the
               coordinated EMEA filing process                       *********
</TABLE>

          provided, however, that if an Approved PLP Compound should reach a
          particular milestone, but is thereafter dropped from further
          development by BMS for whatever reason, then no more milestone
          payments shall be due with respect to any subsequent Approved PLP
          Compound that targets the same Program tRNA Synthetase as the
          abandoned compound, unless and until such subsequent Approved PLP
          Compound reaches the milestone next following the last milestone on
          which a payment was made for the abandoned compound. For example,
          milestone payments would not be required for a subsequent Approved PLP
          Compound targeting the same Program tRNA Synthetase as an abandoned
          compound until the filing of the NDA in one of the designated
          countries, if milestone payments had been made on the abandoned
          compound through initiation of Phase III clinical trials. Payments
          shall be wired to a bank account specified by Cubist within thirty
          (30) days following attaining each such milestone.

3.6  Royalties.
     --------- 

          3.6.1  With respect to each Covered Product, BMS shall pay a royalty
                 on Net Sales of such Covered Product during the Royalty Term
                 for such Covered Product, as follows (based on the sum of the
                 worldwide Net Sales in each Tier multiplied by the applicable
                 royalty rate for that Tier):

<TABLE> 
<CAPTION> 
          Annual Net Sales (in US$ millions) ("Tiers")   Percentage of Net Sales
          --------------------------------------------   -----------------------
                 <S>                                            <C>
                 *********                                      **
                 ***********                                    **
                 ***************                                **
</TABLE> 
    
                 Where the potential use or application for a non-infectious
                 disease indication of any compound or analog thereof that is
                 incorporated as the active substance in a Covered Product was
                 identified (whether in laboratory notebooks, patent
                 applications), or otherwise) by BMS prior to the date that such
                 compound or analog was identified as a Hit hereunder, then no
                 royalty shall be due on such Covered Product to the extent sold
                 for the treatment or prevention of diseases or conditions other
                 than infectious diseases.





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<PAGE>
 
                                     -23-


                 In the event that (i) the manufacture, use or sale of a Covered
                 Product in a country is not covered by a Valid Claim owned or
                 controlled by BMS or any of its Affiliates, and (ii) a generic
                 competitive product has been approved in such country, then the
                 royalty rates set forth above shall be reduced by ***** percent
                 (e.g., ******************************) in such country.

                 Royalties for Net Sales of any Covered Product in any given
                 country shall be due and payable only during the Royalty Term
                 for such Covered Product in such country; thereafter, BMS shall
                 be entitled to continue to sell such Covered Product in such
                 country without further compensation to Cubist.

          3.6.2  In the event that BMS must make royalty payments under a
                 license from a Third Party in respect of any patents that are
                 necessary to make, have made, use or sell a Covered Product,
                 then BMS may reduce the royalty otherwise owing on Net Sales of
                 such Covered Product by *** of the amount paid as a royalty to
                 such Third Party, but in no event shall the royalty payable
                 hereunder with respect to such Covered Product be reduced by
                 more than *** of the royalty otherwise payable hereunder during
                 any quarter (with carryover of any excess, unused royalty
                 credit to ensuing quarters). Where the royalty payable to such
                 Third Party is not tied specifically to Net Sales of such
                 Product or where the fee to obtain such license is based on
                 other factors (such as up-front licensing fees), the allocation
                 of such amounts or royalties payable by such party to such
                 Third Party will be determined in an equitable manner. If the
                 parties cannot mutually agree upon same within 90 days after
                 either party serves written notice on the other as to same, the
                 dispute shall be determined by binding arbitration in
                 accordance with this Agreement.

     3.7  Adjustments.  No payments will be due under sections 3.3(b), 3.4 and
          -----------                                                         
          3.5:

          (i) where the active substance in such Lead Compound, Approved PLP
          Compound or Covered Product (or, if such active substance is an analog
          of the original active substance in such Lead Compound, Approved PLP
          Compound or Covered Product, then such original active substance) was
          known to or had been identified by BMS or any of its Affiliates or
          funded research collaborators, or was





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<PAGE>
 
                                     -24-


          generally known to the public, as possessing Inhibitory Activity
          against an Aminoacyl-tRNA Synthetase for which such Lead Compound,
          Approved PLP Compound, or Covered Product is targeted prior to the
          date that such active substance was first identified as having
          Inhibitory Activity against an Aminoacyl-tRNA Synthetase by reason of
          the Primary and/or Secondary Screening Programs conducted by a party
          under this Agreement; or

          (ii) where the right to make, have made, use or sell such Lead
          Compound, Approved PLP Compound, Covered Product, or the active
          substance in same (or, if such active substance in such Lead Compound,
          Approved PLP Compound or Covered Product is an analog of the another
          active substance, then such original active substance) was or is
          licensed to BMS or its Affiliates by a Third Party (A) who had
          identified or ascertained, independently of any activity conducted by
          BMS or Cubist pursuant to this Agreement, that such Lead Compound,
          Approved PLP Compound, Covered Product, or the active substance in
          same (or, if such active substance in such Lead Compound, Approved PLP
          Compound or Covered Product is an analog of the another active
          substance, then such original active substance), possessed Inhibitory
          Activity against an Aminoacyl-tRNA Synthetase for which such Lead
          Compound, Approved PLP Compound, or Covered Product is targeted, and
          (B) who had identified or ascertained same prior to the date that such
          active substance was first identified as having Inhibitory Activity
          against an Aminoacyl-tRNA Synthetase by reason of the Primary and/or
          Secondary Screening Programs conducted by a party under this
          Agreement, or

          (iii) where the Lead Compound or Approved PLP Compound that would
          otherwise trigger such milestones was an Approved PLP Compound or a
          marketed drug as of the Effective Date.

     3.8  Interest on Late Payments.  In the event that BMS fails to make any
          -------------------------                                          
          payment required under this Article 3 when due, interest on the unpaid
          balance shall accrue at an annual rate equal to the lesser of (i) ten
          percent (10%) per annum. or (ii) the maximum amount permitted by
          applicable law, commencing as of the due date.
<PAGE>
 
                                     -25-


4.0  [INTENTIONALLY OMITTED]

5.0  INTELLECTUAL PROPERTY RIGHTS

The following provisions relate to rights in the intellectual property developed
by Cubist or BMS, or both, during the term of this Agreement:

5.1  License Rights.
     -------------- 

     5.1.1  Subject to section 2.1.1(c)(ii), Cubist grants to BMS and its
            Affiliates a worldwide right and license under any Cubist Technology
            and Cubist Patent Rights (A) to run the Primary Screening Program to
            identify inhibitors of any Program tRNA Synthetase, and (B) to
            conduct research and drug development of Hits, Lead Compounds and
            Approved PLP Compounds resulting from the Primary and/or Secondary
            Screening Programs pursuant to, and in accordance with, the terms
            and conditions of this Agreement. Such rights shall be subject to
            all payments required in article 3 hereof, and shall continue until,
            and to the extent, terminated in accordance with article 12 hereof.
            Subject to section 2.1.1(c)(ii) hereof, such rights granted under
            subparagraph (A) of this section 5.1.1 shall be exclusive during the
            Research Term and non-exclusive thereafter. The rights granted under
            subparagraph (B) of this section 5.1.1 shall be non-exclusive and do
            not encompass rights granted pursuant to section 5.1.2 hereof.

     5.1.2  Subject to article 12 hereof, Cubist grants to BMS and its
            Affiliates a worldwide, non-exclusive right and license under any
            Cubist Technology and Cubist Patent Rights to screen Hits, Lead
            Compounds and Approved PLP Compounds in a Secondary Screening
            Program in order to identify inhibitors of any eubacterial, fungal
            and human Arninoacyl-tRNA Synthetases; provided, that BMS may
            exercise the rights granted under this section 5.1.2 Only to the
            extent that Cubist is not fulfilling its obligations under section
            2.1.1(c) hereof. In the event that BMS is entitled to exercise such
            rights, Cubist will assist BMS by providing to BMS, without charge
            (but only to the extent such Biological Materials may be then
            already available to Cubist), such Biological Materials as are
            necessary to effectuate same. Such rights shall be subject to all
            payments required in article 3 hereof, and shall continue until, and
            to the extent, terminated in accordance with article 12 hereof.
<PAGE>
 
                                     -26-


     5.1.3  If, in the course of conducting the Research Program, BMS should
            make any improvement to the Screening Modules provided by Cubist to
            BMS hereunder, BMS hereby grants to Cubist a fully paid-up, royalty-
            free, irrevocable, non-exclusive, worldwide and perpetual right and
            license to use and practice such improvement (including under any
            patent rights that BMS may obtain covering such improvement) for any
            purpose that is not inconsistent with the other terms and conditions
            of this Agreement.

5.2  Ownership Rights.
     ---------------- 

     5.2.1  Except as provided in sections 2.5.3 and 5.2.3, nothing in this
            Agreement is intended to convey or transfer ownership by one party
            to the other of any rights, title or interest in any Confidential
            Information, know-how, Technology, or patent rights owned or
            Controlled by a party. Except as expressly provided for in sections
            2.1, 5.1 and 5.3 of this Agreement, nothing in this Agreement shall
            be construed as a license or sublicense by one party to the other of
            any rights in any Biological Materials, Technology or Patent Rights
            owned or Controlled by a party or its Affiliates.

     5.2.2  BMS shall own all Inventions and other Technology made solely by its
            employees and agents, and all patent applications and patents
            claiming such Inventions. Subject to section 5.2.3, Cubist shall own
            all Inventions and other Technology made solely by its employees and
            agents, and all patent applications and patents claiming such
            Inventions. Subject to Section 5.2.3, all Inventions and other
            Technology made jointly by employees or agents of BMS and employees
            or agents of Cubist shall be owned jointly by BMS and Cubist. All
            joint Inventions (and all Patent Rights obtained thereon) and all
            Technology jointly developed by Cubist and BMS during the Research
            Term may be freely exploited by either party without further
            obligation to the other, subject to section 5.2.3 and the remaining
            terms and conditions of this Agreement. Determinations of
            inventorship shall be made in accordance with U.S. patent law.

     5.2.3  All rights, title and interest owned or Controlled by Cubist or its
            Affiliates in any Inventions and Technology pertaining to any
            indication or use of any Hit, Lead Compound, Approved PLP Compound
            or Covered Product (or of analogs of the class
<PAGE>
 
                                     -27-


            of compounds to which the same may pertain) that may be conceived or
            reduced to practice at any time during the Contract Period solely by
            Cubist employees or by a Third Party under contract with Cubist, or
            jointly by any of them with others, in connection with the
            activities conducted by Cubist under this Agreement, and all rights,
            title and interest Cubist may have in any Patent Rights that may be
            obtained on any of the foregoing (collectively, "Product Invention
            Rights"), shall be owned exclusively by BMS, and shall be deemed to
            be and have been automatically assigned to BMS by reason of Cubist's
            execution of this Agreement. Cubist shall promptly report any such
            Invention to BMS in sufficient detail to enable BMS to assess
            whether a patent application should be filed. If BMS desires to file
            patent applications on any such Invention, it will do so at its
            option and expense, and Cubist will provide reasonable cooperation
            as BMS may request (with BMS reimbursing Cubist for any out-of-
            pocket costs so incurred) in obtaining and filing for any patent
            protection thereon in BMS name and will execute any documents or
            other instruments as may be reasonably requested by BMS to fully
            vest exclusive ownership of such Product Invention Rights in BMS.
            BMS shall be under no obligation, express or implied, to develop,
            market, or otherwise utilize any such Product Invention Rights.

5.3  Sublicensing.  BMS shall have the right to sublicense any of the
     ------------                                                    
     rights licensed to it by Cubist hereunder to any Affiliate of BMS and,
     subject to Cubist's approval (not to be unreasonably withheld), to a
     Third Party, provided that such Affiliate or Third Party shall have
     agreed to adhere to the terms and conditions of this Agreement and
     provided that BMS shall not be relieved of its obligations pursuant to
     this Agreement.

6.0  PAYMENTS OF ROYALTIES, ACCOUNTING FOR ROYALTIES, RECORDS

6.1  Payment Term.  BMS shall pay Cubist a royalty based on the Net Sales
     ------------                                                        
     of each Covered Product as provided in section 3.6 hereof. Such royalty
     shall be paid with respect to each country of the world from the date of
     the First Commercial Sale of such Covered Product in each country for the
     duration of the Royalty Term with respect to such country; thereafter, BMS
     shall be entitled to continue to sell such Covered Product in such country
     without further compensation to Cubist hereunder.
<PAGE>
 
                                     -28-


6.2  Payment Dates.  Royalties shall be paid by BMS on Net Sales within
     -------------                                                     
     sixty (60) days after the end of each calendar quarter in which such Net
     Sales are made. Such payments shall be accompanied by a statement showing
     all relevant sales information including the information employed to
     calculate Net Sales of each Covered Product in each country, and the
     calculation of the amount of royalty due.

6.3  Accounting.  The Net Sales used for computing the royalties payable to
     ----------                                                            
     Cubist by BMS shall be computed in U.S. dollars and paid by wire transfer
     or other mutually acceptable means. For purposes of determining the amount
     of royalties due, the amount of Net Sales in any foreign currency shall be
     computed by converting such amount into dollars at the prevailing
     commercial rate of exchange for purchasing dollars with such foreign
     currency as quoted by the Wall Street Journal at the close of the last
     business day of the calendar quarter for which the relevant royalty payment
     is to be made by BMS.

6.4  Records.  BMS shall keep for three (3) years from the date of each
     -------                                                           
     payment of royalties complete and accurate records of sales and all other
     information necessary to calculate Net Sales of each Covered Product in
     sufficient detail to allow the accrued royalties to be determined
     accurately. Cubist shall have the right to cause an independent, certified
     public accountant (who has executed a confidentiality agreement with BMS
     reasonably acceptable to BMS) to audit such records at the place or places
     of business where such records are customarily kept in order to verify the
     accuracy of the reports of Net Sales and royalty payments for the preceding
     three years. Such audits may be exercised during normal business hours once
     a year upon 30 days' advance written notice to BMS. Cubist shall bear the
     full cost of such audit unless such audit discloses a variance of more than
     5% from the amount of the royalties due under this Agreement, in which
     event, BMS shall bear the full cost of such audit. Cubist agrees not to
     disclose confidential information concerning royalty payments and reports,
     and all information learned in the course of any audit or inspection,
     except to the extent necessary for Cubist to reveal such information in
     order to enforce its rights under this Agreement or if disclosure is
     required by law.

7.0  INFRINGEMENT BY THIRD PARTIES

7.1  Actual or Threatened Infringement of a Covered Product.  If
     ------------------------------------------------------     
     information comes to the attention of BMS or Cubist to the effect
<PAGE>
 
                                     -29-


     that any Patent Rights owned or Controlled by BMS or its Affiliates
     relating to a Covered Product are being, have been or are threatened to be
     infringed by a Third Party not Affiliated with BMS, BMS shall have the sole
     right, at its expense, to take and control all action as BMS may deem
     necessary or appropriate to prosecute or prevent such unlawful
     infringement, including the right to bring, defend, settle, compromise, or
     appeal any suit, action or proceeding involving any such infringement. If
     BMS determines that it is necessary or desirable to bring an infringement
     action and for Cubist to join any such suit, action or proceeding, Cubist
     shall, at BMS's expense, execute all papers, provide full cooperation and
     assistance to BMS in connection with such proceeding, and, if necessary,
     take such other actions as may be reasonably required to permit BMS to act
     in Cubist's name (including the furnishing of a power of attorney), and BMS
     will reimburse Cubist for any out-of-pocket costs incurred in connection
     therewith; provided, however, that BMS may not settle any patent
     infringement litigation under this Section 7.1 in a manner that adversely
     affects Cubist's Patent Rights or Technology or that would constitute an
     amendment of this Agreement without Cubist's written consent (not to be
     unreasonably withheld or delayed). Any recovery realized as a result of
     such litigation, after reimbursement of any litigation expenses of BMS and
     Cubist, *******************************************************************
     ***************************************************************************
     *******************************************************************
     *************************************************************.

7.2  Actual or Threatened Infringement of a Cubist Patent Rights.
     ----------------------------------------------------------- 

     7.2.1  BMS and Cubist shall promptly notify the other in writing of any
            alleged or threatened infringement of any Patent Rights owned or
            Controlled by Cubist or its Affiliates that are licensed to BMS
            under this Agreement of which either becomes aware. Both parties
            shall use their best efforts in cooperating with each other to
            terminate such infringement without litigation. Cubist shall have
            the first right to bring and control any action or proceeding with
            respect to such infringement at its own expense and by counsel of
            its own choice as to any such Patent Rights, and BMS shall have the
            right, at its own expense, to be represented in any action involving
            any such Patent Rights using counsel of its own choice.





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -30-


     7.2.2  If, during the Research Term, Cubist fails to bring an action or
            proceeding within (i) 120 days following receipt of written notice
            from BMS with respect to such alleged infringement or (ii) 10 days
            before the time limit, if any, set forth in the appropriate laws and
            regulations for the filing of such actions, whichever comes first,
            with respect to those Patent Rights as to which Cubist has the first
            right to bring and control an action under section 7.2.1 above and
            which are exclusively licensed to BMS hereunder, BMS shall have the
            right to bring and control any such action at its own expense and by
            counsel of its own choice, and Cubist shall have the right, at its
            own expense, to be represented in any such action by counsel of its
            own choice.

     7.2.3  In the event a party brings an infringement action under this
            section 7.2, the other party shall cooperate fully, including if
            required to bring such action, the furnishing of a power of
            attorney. Neither party shall have the right to settle any patent
            infringement litigation under this Section 7.2 in a manner that
            diminishes the rights licensed to the other party hereunder or which
            would constitute an amendment of this Agreement, without the consent
            of such other party (not to be unreasonably withheld or delayed).
            Except as otherwise agreed to by the parties as part of a cost
            sharing arrangement, any recovery realized as a result of such
            litigation, ********************************************************
            *********************************************************

8.0  DEFENSE OF INFRINGEMENT CLAIMS

8.1  Defense of Infringement Claims Pertaining to Lead Compounds, Approved
     ---------------------------------------------------------------------
     PLP Compounds. and Products.
     --------------------------- 

     Cubist will cooperate with BMS, at BMS's expense, in the defense of any
     suit, action or proceeding against Cubist, BMS, any BMS Affiliate, or any
     licensee of BMS alleging the infringement of the intellectual property
     rights of a third party by reason of the manufacture, use or sale of a Lead
     Compound, Approved PLP Compound, or Covered Product. Cubist shall give to
     BMS all authority (including the right to exclusive control of the defense
     of any such suit, action or proceeding and the exclusive right to
     compromise, litigate, settle or otherwise dispose of any such suit, action
     or proceeding), information and assistance necessary to





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -31-


     defend or settle any such suit, action or proceeding; provided, however,
     BMS shall obtain Cubist's prior written consent to all or such part of any
     settlement which requires payment or other action by Cubist (or any of its
     Affiliates or licensees) or which may have an adverse effect on the
     continuing use of Cubist's Technology or Patent Rights by Cubist, its
     Affiliates or licensees; and provided, further, that if BMS should require
     that Cubist (or any of its Affiliates or licensees) should institute or
     join in any such suit, action or proceeding pursuant to this Section 8.1,
     BMS shall hold Cubist (and any such Affiliate or licensee, as applicable)
     free, clear and harmless from any and all costs and expenses of such
     litigation, including reasonable attorneys' fees, and Cubist shall execute
     all documents, provide pertinent records, and take all other actions,
     including requiring persons within its control to give testimony, which may
     be reasonably required in connection with such litigation. Subject to the
     foregoing, Cubist (and such Affiliates and licensees) may participate in
     any such litigation or other proceeding using attorneys of their choice and
     at their expense.

8.2  Defense of Infringement Claims Pertaining to Patent Rights Owned or
     -------------------------------------------------------------------
     Controlled by Cubist.
     -------------------- 

     BMS will cooperate with Cubist, at Cubist's expense, in the defense of any
     suit, action or proceeding against Cubist, any Cubist Affiliate, BMS, any
     BMS Affiliate, or any licensee of BMS alleging the infringement of the
     intellectual property rights of a third party by reason of the use of the
     Primary Screening Modules or of the Patent and Technology rights licensed
     by Cubist to BMS under this Agreement. Cubist shall give BMS prompt written
     notice of the commencement of any such suit, action, proceeding or claim of
     infringement and will furnish BMS a copy of each communication relating to
     the alleged infringement. BMS shall give to Cubist all authority (including
     the right to exclusive control of the defense of any such suit, action or
     proceeding and the exclusive right, after consultation with BMS, to
     compromise, litigate, settle or otherwise dispose of any such suit, action
     or proceeding), information and assistance necessary to defend or settle
     any such suit, action or proceeding; provided, however, Cubist shall obtain
     BMS's prior written consent to all or such part of any settlement which
     requires payment or other action by BMS, its Affiliates, or licensees, or
     which may have an adverse effect on the continuing use of such Modules or
     the rights granted hereunder by BMS, its Affiliates or licensees or which
     would permit the use by a Third Party of such rights and Modules in a
     manner that competes with BMS' use of
<PAGE>
 
                                     -32-


     same hereunder in violation of this Agreement. If Cubist should require
     that BMS (or any of its Affiliates or licensees) should institute or join
     any such suit, action or proceeding pursuant to this Section 8.1.2, Cubist
     shall hold BMS (and such Affiliates and licensees) free, clear and harmless
     from any and all costs and expenses of such litigation, including
     reasonable attorneys' fees, and BMS shall execute all documents, provide
     pertinent records, and take all other actions, including requiring persons
     within its control to give testimony, which may reasonably be required in
     connection with the prosecution of such suit, action or proceeding.

9.0  TREATMENT OF CONFIDENTIAL INFORMATION

9.1  Confidentiality
     ---------------

     9.1.1  BMS and Cubist each recognize that the other's Confidential
            Information constitutes highly valuable, confidential information.
            Subject to the terms and conditions of this Agreement, BMS and
            Cubist each agree that, during the term of this Agreement and for
            five (5) years thereafter, it will use all reasonable efforts to
            keep confidential, and will cause its Affiliates to use reasonable
            efforts to keep confidential, all Cubist Confidential Information or
            BMS Confidential Information, as the case may be, that is disclosed
            to it or to any of its Affiliates pursuant to this Agreement.
            Neither BMS nor Cubist nor any of their respective Affiliates shall
            use such Confidential Information except as expressly permitted in
            this Agreement.

     9.1.2  BMS and Cubist each agree that any disclosure of the other's
            Confidential Information to any officer, employee, contractor,
            consultant, sublicensee, or agent of the other party or of any of
            its Affiliates shall be made only if and to the extent necessary to
            carry out its responsibilities under this Agreement and to exercise
            the rights granted to it hereunder and shall be limited to the
            maximum extent possible consistent with such responsibilities and
            rights. BMS and Cubist may disclose the other's Confidential
            Information to any Third Parties under the preceding sentence,
            provided that such Third Party shall have first executed an
            agreement with the party disclosing such Confidential Information to
            it that obligates such Third Party to maintain same in confidence in
            the same manner as the party disclosing same to it is required to do
            so hereunder. Each party shall take
<PAGE>
 
                                     -33-


            such action, and shall cause its Affiliates to take such action, to
            preserve the confidentiality of each other's Confidential
            Information as it would customarily take to preserve the
            confidentiality of its own Confidential Information. Each party,
            upon the other's request, will return all the Confidential
            Information disclosed to the other party pursuant to this Agreement,
            including all copies and extracts of documents, within sixty (60)
            days of the request upon the termination of this Agreement except
            for one (1) copy which may be kept for the purpose of complying with
            continuing obligations under this Agreement.

     9.1.3  Cubist and BMS each represent that all of its employees, and any
            consultants to such party, participating in the Primary and
            Secondary Screening Programs or any other phase of the Alliance, who
            shall have access to BMS Confidential Information or Cubist
            Confidential Information are bound by agreement to maintain such
            information in confidence.

     9.1.4  Confidential Information shall not include any information which the
            receiving party can prove by competent evidence:

            (i)    is now, or hereafter becomes, through no act or failure to
                   act on the part of the receiving party, generally known or
                   available;
                   
            (ii)   is known by the receiving party at the time of receiving such
                   information, as evidenced by its records;
       
            (iii)  is hereafter furnished to the receiving party without
                   restriction as to disclosure or use by a Third Party lawfully
                   entitled to so furnish same;
       
            (iv)   is independently developed by the employees, agents or
                   contractors of the receiving party without the aid,
                   application or use of the disclosing party's Confidential
                   Information; or
                   
            (v)    is the subject of a written permission to disclose provided
                   by the disclosing party; or
                   
            (vi)   is provided by the disclosing party to a Third Party without
                   restriction as to confidentiality.
<PAGE>
 
                                  -34-       


     A party may also disclose Confidential Information of the other where
     required to do so by law or legal process, provided that, in such event,
     the party required to so disclose shall give maximum practical advance
     notice of same to the other party and will seek, at the request and expense
     of the other party, all confidential treatment and protection for such
     disclosure as is permitted by applicable law.

     The parties agree that the material financial terms of this Agreement will
     be considered Confidential Information of both parties. Notwithstanding the
     foregoing, either party may disclose such terms as are required to be
     disclosed in its financial statements or by law or under strictures of
     confidentiality to bona fide potential sublicensees. Either party shall
     have the further right to disclose the material financial terms of this
     Agreement under strictures of confidentiality to any potential acquiror,
     merger partner, bank, venture capital firm, or other financial institution
     to obtain financing, or other bona fide potential strategic partner.

9.2  Publication.  Notwithstanding any matter set forth with particularity
     -----------                                                          
     in this Agreement to the contrary but subject to section 9.1 hereof,
     results obtained in the course of the Primary and Secondary Screening
     Programs may be submitted for publication following scientific review by
     the Research Committee and subsequent approval by both Cubist's and BMS's
     managements, which approval shall not be unreasonably withheld. After
     receipt of the proposed publication by both BMS's and Cubist's managements,
     written approval or disapproval shall be provided within thirty (30) days
     for a manuscript, within fourteen (14) days for an abstract for
     presentation at, or inclusion in the proceedings of a scientific meeting,
     and within fourteen (14) days for a transcript of an oral presentation to
     be given at a scientific meeting. All publications pertaining to the
     research and development (other than the results obtained in the Primary
     and Secondary Screening Programs) of any Lead Compound, Approved PLP
     Compound and any Product shall be made, approved, and determined solely by
     BMS.

9.3  Publicly.  Except as required by law and as provided in this article
     --------                                                            
     9, neither party may disclose the terms of this Agreement nor the research
     contemplated hereunder without 
<PAGE>
 
                                     -35-


            the written consent of the other party, which consent shall not be
            unreasonably withheld. It is understood that the existence of this
            Agreement is anticipated to form the basis of a mutual press release
            that will be released by both parties promptly following the
            Effective Date.

10.0  PROVISIONS CONCERNING THE FILING, PROSECUTION AND MAINTENANCE OF
      PATENT RIGHTS

      10.1  Inventions Pertaining to Primary Modules.  With respect to an
            ----------------------------------------                     
            Invention conceived or reduced to practice by either party at any
            time prior to the end of the Research Term that relates to the
            manufacture or use of the Primary Screening Modules or to the Patent
            Rights owned or Controlled by Cubist or its Affiliates that are
            licensed to BMS hereunder, the inventing party shall promptly notify
            the other party, and the parties shall discuss such Invention and
            the desirability of filing patent applications covering such
            Invention. Cubist shall have the first right to file, prosecute,
            maintain, and enforce Patent Rights for any such Inventions that are
            made solely by it or jointly by it with BMS or others, at Cubist's
            expense, and Cubist shall consider in good faith the requests and
            suggestions of the BMS with respect to strategies for filing and
            prosecuting such patent applications. BMS shall have the right to
            file, prosecute, maintain and enforce Patent Rights for any such
            Inventions made solely by BMS or its affiliates that relate to the
            manufacture or use of the Primary Screening Modules or to the Patent
            Rights owned or Controlled by Cubist or its Affiliates that are
            licensed to BMS hereunder. Subject to the remaining provisions of
            this section 10.1, the party having the right to control the
            prosecution and filing of any such Invention shall file and
            prosecute same in the name(s) of the inventors. The party
            controlling such filing and prosecution shall keep the other party
            informed of progress with regard to the filing, prosecution,
            maintenance, enforcement, and defense of patents and patent
            applications that are subject to this Section 10.1, and, if the
            inventing party decides not to pursue protection at any time for any
            such Invention in any particular country, it shall give the other
            party reasonable notice to this effect. After that notice, the other
            party may, at its expense, file, prosecute, maintain and enforce a
            patent application or patent covering such Invention in such country
            and shall own such patent applications or patents, subject to any
            license rights expressly
<PAGE>
 
                                     -36-


            granted hereunder. In such case, the inventing party shall also
            assign its rights in such patent applications or patents to the
            other party as necessary to convey ownership to the other party.

            Each party shall fully cooperate with the other party controlling
            such filing, prosecution and maintenance, and will execute such
            documents or other instruments as may be requested by the
            controlling party in order to fully vest the rights associated with
            any such Invention as set forth herein. The controlling party will
            reimburse the other party for any out-of-pocket costs incurred by
            the other party in connection therewith.

            Where the non-controlling party is the licensee hereunder of any
            rights that are or will be licensed to it under the patent
            application being filed for an Invention, the party controlling such
            filings and prosecutions shall provide to the other copies of all
            patent applications that are part of Patent Rights covered by this
            section 10.1 prior to filing, for the purpose of obtaining
            substantive comment of the other party's patent counsel. The
            controlling party shall also provide to such other party copies of
            all documents relating to prosecution of all such patent
            applications in a timely manner and shall also provide a report
            every six (6) months detailing their status.

            BMS shall have the right to file on behalf of and as a agent for
            Cubist all applications and take all actions necessary to obtain
            patent extensions pursuant to 35 USC Section 156 and foreign
            counterparts for Patent Rights described in this Section 10.1 that
            are licensed to BMS hereunder. Cubist agrees, to sign, at BMS's
            expense, such further documents and take such further actions as may
            be requested by BMS in this regard.

     10.2  Inventions Pertaining to Hits and Products.  BMS shall have the sole
           ------------------------------------------                          
           right to file, prosecute, maintain and enforce patents in its own
           name for any Inventions invented solely by BMS or jointly by BMS with
           Cubist or others, or that are assigned by Cubist to BMS pursuant to
           article 5 hereof, at BMS own expense, pertaining to the manufacture,
           use or sale of any Hit, Lead Compound, Approved PLP Compound, or
           Product (or analogs of the same class as the foregoing), and to take
           any and all actions, including abandonment of claims, as
<PAGE>
 
                                     -37-


           BMS may deem necessary or appropriate in its sole and absolute
           discretion. BMS shall keep Cubist informed of progress with regard to
           the filing, prosecution, issuance, maintenance, enforcement and
           defense of patents and patent applications subject to this Section
           10.2, but shall not be required to provide copies of any applications
           or consult with Cubist with regard to filing, prosecution, or
           maintenance of same.

11.0 REPRESENTATIONS, WARRANTIES AND COVENANTS

11.1  Mutual Representations and Warranties.  The parties make the
      -------------------------------------                       
      following representations and warranties to each other:

     11.1.1  Each party hereby represents and warrants that such party (a) is
             duly organized and validly existing under the laws of the state of
             its incorporation and has full corporate power and authority to
             enter into this Agreement and to carry out the provisions hereof,
             (b) has the requisite power and authority and the legal right to
             own and operate its property and assets, to lease the property and
             assets it operates under lease, and to carry on its business as it
             is now being conducted; and (c) is in compliance with all
             requirements of applicable law, except to the extent that any
             noncompliance would not have a material adverse. effect on the
             properties, business, financial or other condition of it and would
             not materially adversely affect its ability to perform its
             obligations under the Agreement.

     11.1.2  Due Authorization.  Each party hereby represents and warrants that
             -----------------                                                 
             such party (a) has the requisite power and authority and the legal
             right to enter into the Agreement and to perform its obligations
             hereunder;. and (b) has taken all necessary action on its part to
             authorize the execution and delivery of the Agreement and the
             performance of its obligations hereunder.

     11.1.3  Binding Agreement.  Each party hereby represents and warrants to
             -----------------                                               
             the other that:

          (a) this Agreement has been duly executed and delivered on its behalf
          and is a legal and valid obligation binding upon it and is enforceable
          in accordance with its terms; (b) the execution, delivery and
          performance of this Agreement by such party does not conflict with any
          agreement, instrument
<PAGE>
 
                                     -38-


          or understanding, oral or written, to which it is a party or by which
          it may be bound, nor violate any law or regulation of any court,
          governmental body or administrative or other agency having authority
          over it; and (c) all necessary consents, approvals and authorizations
          of all governmental authorities and other persons required to be
          obtained by it in connection with the Agreement have been obtained.

    11.2  Cubist Technology Representations and Warranties.  Cubist represents
          ------------------------------------------------                    
          and warrants to BMS as of the Effective Date the following:

          11.2.1 The Patent Rights listed on Exhibit 11.2 list all Cubist Patent
                 Rights owned or Controlled by Cubist in the Territory, and such
                 Exhibits specify the jurisdiction(s) by or in which such right
                 has been issued or registered or in which an application for
                 such issuance or registration has been filed, including
                 respective registration or application numbers. To the best
                 knowledge of the current officers and directors of Cubist, the
                 issued Patent Rights are valid and in full force and effect.

          11.2.2 Except as disclosed on Exhibit 11.2, to the best knowledge of
                 Cubist's current officers and directors, (i) the use of the
                 Cubist Technology and any Cubist Patent Rights in the exercise
                 by BMS of the rights granted to it hereunder does not infringe
                 upon any patent rights, copyrights or other proprietary rights
                 of any Affiliate of Cubist or any Third Party in the Territory;
                 (ii) Cubist has no knowledge of any infringement by any Third
                 Party of any of the Patent Rights in the Territory; and (iii)
                 Cubist and each of its Affiliates are not subject to any
                 outstanding order, judgment or decree of any court or
                 administrative agency, and each has not entered into any
                 stipulation or agreement, restricting (A) its use of the Patent
                 Rights in connection with the manufacture, development, use, or
                 licensing of the Primary Screening Modules, or (B) Cubist's
                 ability to perform its obligations under this Agreement
                 (including without limitation its obligations hereunder with
                 respect to the Primary and Secondary Screening Programs).

          11.2.3 There is no action, suit or proceeding pending or, to the
                 knowledge of its current officers and directors, that has been
                 threatened in writing by any Third Party against Cubist or
<PAGE>
 
                                     -39-


                 its Affiliates which, if adversely determined, would have a
                 material adverse effect upon the ability of BMS to fully
                 utilize or exercise the Cubist Patent Rights or Cubist
                 Technology licensed to it hereunder.

          11.2.4 The Cubist Technology and Cubist Patent Rights licensed by
                 Cubist to BMS pursuant to this Agreement have not been obtained
                 by Cubist or its Affiliates in violation of any contractual or
                 fiduciary obligation to which Cubist or any of its Affiliates
                 or any of its or their employees or, to the best knowledge of
                 the current officers and directors of Cubist, its or their
                 contractors or predecessors-in-interest (and the employees of
                 such contractors or predecessors-in-interests), is or was a
                 party, or by misappropriation of the trade secrets of any Third
                 Party, and the exercise by BMS or its Affiliates of the rights
                 licensed by Cubist to it hereunder will not violate any such
                 contractual or fiduciary obligation owed to any such Third
                 Party or render BMS liable for the payment of any royalty
                 attributable to or arising out of any such contractual or
                 fiduciary obligation or any such misappropriation. There are no
                 predecessors-in-interest to Cubist.

          11.2.5 Other than the Patent Rights listed on Exhibit 11.2 and the
                 Cubist Technology, there are no licenses under any patent
                 rights, and, to the best knowledge of the current officers and
                 directors of Cubist, under any other intellectual property or
                 other proprietary rights owned or controlled by any Cubist
                 Affiliate or Third Party which are used by Cubist in connection
                 with the manufacture, development, use or sale of the Primary
                 Screening Modules for PSM-Program tRNA Synthetases.

          11.2.6 Cubist has not as of the Effective Date agreed, and during the
                 Research Term will not agree, with any Third Party that it may
                 make or use any Primary Screening Modules for primary screening
                 purposes or that Cubist will supply Primary Screening Modules
                 to such Third Party for primary screening purposes. Cubist will
                 permit such Third Party to make or use such Primary Screening
                 Modules only for secondary screening purposes on terms that art
                 consistent with the secondary screening terms granted BMS
                 hereunder.
<PAGE>
 
                                     -40-


                 Cubist further represents and warrants that:

                 (A) as of the Effective Date it has not licensed, and that
                     during the term of this Agreement it will not license, to
                     any Third Party any Technology or Patent Rights owned or
                     Controlled by Cubist to allow such Third Party to make or
                     use, and

                 (B) Cubist has not as of the Effective Date agreed to supply to
                     a Third Party or otherwise permit a Third Party to use, and
                     that during the term of this Agreement it will not supply
                     or otherwise permit a Third Party to use,

                 primary screening modules in any primary screening program
                 targeting Inhibitory Activity against Non-PSM-Program tRNA
                 Synthetases, the terms of which would limit or restrict Cubist
                 in any way from conducting in accordance with this Agreement
                 the Secondary Screening Program against any such Non-PSM-
                 Program tRNA Synthetase on Hits arising hereunder.

     11.3   Mutual Indemnification.  Each party hereby agrees to indemnify,
            ----------------------                                         
            defend and hold the other party, its Affiliates, its licensees, and
            its and their officers, directors, employees, consultants,
            contractors, sublicensees and agents (collectively, the
            "Indemnitees") harmless from and against any and all damages or
            other amounts payable to a Third Party, as well as any reasonable
            attorneys' fees and costs of litigation incurred by such Indemnitee
            as to such Claim until the indemnifying party has acknowledged that
            it will provide indemnification hereunder with respect to such Claim
            as provided below, (collectively, "Damages") resulting from claims,
            suits, proceedings or causes of action ("Claims") brought by such
            Third Party based on any research activities conducted by or through
            the indemnifying party or any use by an Indemnitee of any of the
            rights licensed to such Indemnitee pursuant to Article 5 hereof,
            except to the extent such Damages are attributable to: (i) a
            violation of law by any Indemnitee, (ii) a violation of any
            contractual or fiduciary duty owed by any Indemnitee to a third
            party, (iii) the misappropriation by any such Indemnitee of the
            trade secrets of any third party, (iv) any negligent or wrongful act
            or omission of any Indemnitee, or (v) any breach of this Agreement
            or misrepresentation contained herein by an Indemnitee.

            It shall be a condition precedent to an Indemnitee's right to seek
            indemnification under this Section 11.3 that it shall inform the
<PAGE>
 
                                     -41-


            indemnifying party of a Claim as soon as reasonably practicable
            after it receives notice of the Claim; shall, if the indemnifying
            party acknowledges that such Claim falls within the scope of its
            indemnification obligations hereunder, permit the indemnifying party
            to assume direction and control of the defense, litigation,
            settlement, appeal or other disposition of the Claim (including the
            right to settle the claim solely for monetary consideration), and
            provided, that the indemnifying party shall seek the prior written
            consent (not to be unreasonably withheld or delayed) of any such
            Indemnitee as to any settlement which would restrict such
            Indemnitee's continuing business operations or reduce the scope of
            or adversely affect the rights licensed to such Indemnitee under
            this Agreement; and shall fully cooperate (including providing
            access to and copies of pertinent records and making available for
            testimony relevant individuals subject to its control) as requested
            by, and at the expense of, the indemnifying party in the defense of
            the Claim. Provided that an Indemnitee has complied with the
            foregoing, the indemnifying party shall provide attorneys reasonably
            acceptable to the Indemnitee to defend against any such Claim for
            which the indemnifying party has acknowledged its indemnification
            obligation hereunder with respect to such Claim. Subject to the
            foregoing, an Indemnitee may participate in any proceedings
            involving such Claim using attorneys of its/his/her choice and at
            its/his/her expense.

     11.4   BMS Product Indemnification.  BMS agrees to indemnify, defend and
            ---------------------------                                      
            hold Cubist, its Affiliates, and its and their officers, directors,
            employees, consultants, contractors, and agents (collectively, the
            "Cubist Indemnitees") harmless from and against any and all damages
            or other amounts payable to a Third Party, as well as any reasonable
            attorneys' fees and costs of litigation incurred by such Cubist
            Indemnitee as to such Claim until BMS has acknowledged that it will
            provide indemnification hereunder with respect to such Claim as
            provided below, (collectively, "Damages") resulting from claims,
            suits, proceedings or causes of action ("Claims") brought by such
            Third Party based on any manufacture, use or sale of an Approved PLP
            Compound or Covered Product by or through BMS, except to the extent
            such Damages are attributable to: (i) a violation of law by any
            Cubist Indemnitee, (ii) a violation of any contractual or fiduciary
            duty owed by any Cubist Indenmitee to a third party, (iii) the
            misappropriation by any such Cubist Indemnitee of the trade secrets
            of any third party, (iv) any negligent or wrongful act or omission
            of any Cubist Indemnitee, or (v) any
<PAGE>
 
                                     -42-


            breach of this Agreement by an Cubist Indemnitee or
            misrepresentation contained herein.

            It shall be a condition precedent to an Cubist Indemnitee's right to
            seek indemnification under this Section 11.4 that it shall inform
            BMS of a Claim as soon as reasonably practicable after it receives
            notice of the Claim; shall, if BMS acknowledges that such Claim
            falls within the scope of its indemnification obligations hereunder,
            permit BMS to assume direction and control of the defense,
            litigation, settlement, appeal or other disposition of the Claim
            (including the right to settle the claim solely for monetary
            consideration), and provided, that BMS shall seek the prior written
            consent (not to be unreasonably withheld or delayed) of any such
            Cubist Indemnitee as to any settlement which would restrict such
            Cubist's Indemnitee's continuing business operations or reduce the
            scope of or adversely affect the Cubist Patent Rights licensed to
            BMS under this Agreement; and shall fully cooperate (including
            providing access to and copies of pertinent records and making
            available for testimony relevant individuals subject to its control)
            as requested by, and at the expense of, BMS in the defense of the
            Claim. Provided that the Cubist Indemnitee complies with the
            foregoing, BMS shall provide attorneys reasonably acceptable to
            Cubist to defend against any such Claim for which BMS has
            acknowledged its indemnification obligation hereunder. Subject to
            the foregoing, an Cubist Indenmitee may participate in any
            proceedings involving such Claim using attorneys of its/his/her
            choice and at its/his/her expense.

     11.5   Representations and Warranties of BMS.  Except for cispentacin and
            -------------------------------------                             
            indolmycin (and analogs thereof), BMS represents and warrants to
            Cubist that, as of the Effective Date, to the best knowledge of the
            officers and directors of BMS, no compounds or other substances in
            BMS' Materials Library have been identified by, or are known to, BMS
            or its Affiliates as having Inhibitory Activity against any
            Arninoacyl-tRNA Synthetase.

12.0 TERM AND TERMINATION

12.1 Term.  The term of this Agreement will begin on the Effective Date
     ----                                                              
     and shall continue until **************************************************
     **************************

12.2 Termination By Mutual Agreement.  The parties may at any time
     -------------------------------                              
     terminate this Agreement, in whole or in part, by written agreement
     executed by both Cubist and BMS.  In such event, the





                      *Confidential treatment requested:
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<PAGE>
 
                                     -43-


     document effecting such termination shall specify the continuation or
     termination of any license rights granted hereunder, as well as any other
     terms agreed to by both parties.

12.3 Termination for Cause.
     --------------------- 

     12.3.1 Termination by BMS.  In the event that Cubist materially breaches
            ------------------                                               
            any of the rights granted to it, or any of the material duties or
            obligations imposed on Cubist, under this Agreement (for example,
            but without limiting the scope of the foregoing, breach of articles
            2.1.1, 2.5, 5.1, 5.2, and 9.1 hereof), and such breach is not cured
            within 90 days following receipt of written notice from BMS to
            Cubist specifying such breach, then, BMS may either

            (i) terminate this Agreement and/or seek any damages and remedies
            available to it at law or in equity, or

            ***********************************************************
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     12.3.2 Termination by Cubist.  In the event that BMS materially breaches
            ---------------------                                            
            any of the rights granted to it, or any of the material duties and
            obligations imposed on it, under this Agreement (for example, but
            without limiting the scope of the foregoing, breach of articles
            2.1.1, 3.2-3.6, 5.1, 5.2, and 9.1 hereof), and such breach is not
            cured within 90 days





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<PAGE>
 
                                     -44-


            following receipt of written notice from Cubist to BMS specifying
            such breach, then, in lieu of any and all other rights and remedies
            available to Cubist at law or in equity, Cubist may either

            (i)  pursue any remedies and damages available to it at law or in
            equity (other than termination of this Agreement and/or any rights
            licensed to BMS hereunder), or

            (ii) terminate this Agreement and/or any rights licensed to BMS
            hereunder; provided, that in such event:

                 ***********************************************************
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<PAGE>
 
                                     -45-


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                      *****************

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                      ************************

     12.3.3 Dispute, In the event of a dispute between the parties as to
            -------                                                     
            whether a material breach has occurred under this Agreement
            entitling a party to exercise its rights under section 12.3.1 or
            12.3.2 hereof, the dispute shall be resolved pursuant to the dispute
            resolution procedures set forth in section 13.0 hereof.

     12.3.4 No Waiver.  An election of remedy by a party for material breach of
            ---------                                                          
            this Agreement under this section 12.3 on one occasion shall not
            constitute a waiver as to any other remedy that may be available
            under this section 12.3 as to any material breach by the other party
            on another occasion.

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                                     -46-


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                                     -47-


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     12.5   Effect of Bankruptcy.  If a party becomes insolvent or admits in
            --------------------                                            
            writing its inability to pay its debts as they mature or applies for
            or consents to the appointment of a receiver or trustee for any of
            its properties; or a receiver or trustee is appointed for such party
            or a substantial portion of its properties and is not discharged
            within ninety (90) days; or any bankruptcy, reorganization, debt
            arrangement, dissolution, liquidation or other proceeding under any
            bankruptcy or insolvency law is instituted by or against such party
            and, if instituted against such party, it is consented to by such
            party or remains undismissed for ninety (90) days, then

            12.5.1 Notwithstanding any such event, such party shall remain
                   obligated to fulfill its obligations and covenants hereunder,
                   and any failure to do so or other breach hereunder shall
                   entitle the other party to terminate this Agreement in
                   accordance with section 12.3 hereof; and

            12.5.2 It is the parties desire that, if any such receiver, trustee,
                   judge, arbitrator or other adjudicator conducting or
                   controlling such proceedings on behalf of a party should hold
                   that any obligations, covenants or duties of such party
                   hereunder should be suspended or declared unenforceable, in
                   whole or in part, then the rights and benefits granted to the
                   other party hereunder shall remain in full force and effect,





                      *Confidential treatment requested:
      material has been omitted and filed separately with the Commission
<PAGE>
 
                                     -48-

 
            and that any such obligations, covenants or duties shall be reformed
            by such receiver, trustee, judge, arbitrator or other adjudicator so
            as to be enforceable to the maximum extent permitted by applicable
            law and to permit any suspension to be lifted at the earliest
            practicable time.

12.6 Effect of Expiration or Termination.
     ----------------------------------- 

     12.6.1 Expiration or termination of this Agreement shall not relieve the
            parties of any obligation accruing prior to such expiration or
            termination. The obligations and rights of the parties under
            sections 2.1.4, 2.5, 5.1.3, 5.2, 6.0, 7.0, 8.0, 9.0, 10.0, 11.3,
            11.4, 12.3, 12.4, 12.5, 13, and 14 hereof, as well as any sections,
            which, by their intent or meaning are intended to so survive, shall
            survive termination or expiration of this Agreement. Except as
            expressly provided in this Agreement, the rights and obligations of
            the parties under Article 5 hereof shall terminate and be of no
            further force or effect whatsoever upon any termination of this
            Agreement.

     12.6.2 In the event that either party terminates rights granted to the
            other pursuant to Section 12.3 hereof, the defaulting party shall
            promptly return to the other party all Confidential Information and
            Biological Materials of the other party pertaining to the rights so
            terminated.

13.0 DISPUTE RESOLUTION

13.1 Disputes.  The parties recognize that disputes as to certain matters
     --------                                                            
     may from time to time arise during the term of this Agreement which relate
     to either party's rights and/or obligations hereunder or thereunder. It is
     the objective of the parties to establish procedures to facilitate the
     resolution of disputes arising under this Agreement in an expedient manner
     by mutual cooperation and without resort to litigation. To accomplish this
     objective, the parties agree to follow the procedures set forth in this
     Article 13 if and when a dispute arises under this Agreement (including
     without limitation under Article 12 hereof) between the parties or among
     the Research Committee.

13.2 Dispute Resolution Procedures.
     ----------------------------- 

     13.2.1 If the parties or the Research Committee cannot resolve the dispute
            within 20 days of formal request by either party to the other, any
            party may, by written notice to the other, have
<PAGE>
 
                                     -49-


            such dispute referred to their respective officers designated below
            or their successors, for attempted resolution by good faith
            negotiations within 30 days after such notice is received. The
            designated officer of BMS shall have the tie-breaking vote with
            respect to all matters pertaining to the research, development,
            manufacture, use and sale of Hits, Lead Compounds, Approved PLP
            Compounds, and Products; provided, that the such tie-breaking vote
            shall not encompass any matters pertaining to the designation or
            change of the Program tRNA Synthetases that are the subject of this
            Agreement or as to any matter involving the scope or validity of any
            rights licensed to BMS hereunder. Said designated officers are as
            follows:

     For BMS:      President of the Pharmaceutical Research Institute with
                   regard to scientific and technical issues; President of the
                   Pharmaceutical Group with regard to all other matters

     For Cubist:   President

     13.2.2 Any such dispute arising out of or relating to this Agreement which
            is not resolved between the parties or the Steering Committee or the
            designated officers of the parties pursuant to section 13.2.1 shall
            be resolved by final and binding arbitration conducted in New York,
            New York under the then current Licensing Agreement Arbitration
            Rules of the American Arbitration Association ("AAA"). The
            arbitration shall be conducted by one arbitrator who is
            knowledgeable in the subject matter which is at issue in the dispute
            and who is selected by mutual agreement of the parties or, failing
            such agreement, shall be selected according to the AAA rules. In
            conducting the arbitration, the arbitrator shall apply the New York
            Evidence Code, and shall be able to decree any and all relief of an
            equitable nature, including but not limited to such relief as a
            temporary restraining order, a preliminary injunction, a permanent
            injunction, or replevin of property. The arbitrator shall also be
            able to award actual, general or consequential damages, but shall
            not award any other form of damage (e.g., punitive or exemplary
            damages). The parties shall share equally the arbitrator's fees and
            expenses pending the resolution of the arbitration unless the
            arbitrator, pursuant to its right but not its obligations, requires
            the non-prevailing party to bear all or any portion of the costs of
            the
<PAGE>
 
                                     -50-


            prevailing party. The decision of the arbitrator shall be final
            and may be sued on or enforced by the party in whose favor it runs
            in any court of competent jurisdiction at the option of such party.
            The parties shall have such discovery rights as the arbitrator may
            allow.

     13.2.3 Notwithstanding anything to the contrary in this section 13, either
            party may seek immediate injunctive or other interim relief from any
            court of competent jurisdiction with respect to any breach of
            articles 5, 9 or 10 hereof.

14.0 MISCELLANEOUS

     14.1   Assignment.  Notwithstanding any provision of this Agreement to the
            ----------                                                         
            contrary, either party may assign any of its rights or obligations
            under this Agreement in any country to any Affiliates; provided,
            however, that such assignment shall not relieve the assigning party
            of its responsibilities for performance of its obligations under
            this Agreement.

            Either party may also assign its rights or obligations under this
            Agreement in connection with the sale of all or substantially all of
            its assets subject to Section 12.4, or may otherwise assign its
            rights or obligations under this Agreement with the prior written
            consent of the other party. Subject to Section 12.4, this Agreement
            shall survive any merger of either party with or into another party
            and no consent for a merger or similar reorganization shall be
            required hereunder; provided, that in the event of such merger or in
            the event of a sale of all assets, no intellectual property rights
            of the acquiring corporation shall be included in the technology
            licensed hereunder.

     14.2   Binding Effect.  This Agreement shall be binding upon and inure to
            --------------                                                    
            the benefit of the successors and permitted assigns of the parties.
            Any assignment not in accordance with this Agreement shall be void.

     14.3   Force Majeure.  Neither party shall lose any rights hereunder or be
            -------------                                                      
            liable to the other party for damages or losses on account of
            failure of performance by the defaulting party if the failure is
            occasioned by government action, war, fire, explosion, flood,
            strike, lockout, embargo, act of God, or any other similar cause
            beyond the control of the defaulting party, provided that the party
            claiming force majeure has exerted all reasonable efforts to avoid
            or remedy such force majeure.
<PAGE>
 
                                     -51-


     14.4   Notices.  Any notices or communications provided for in this
            -------                                                     
            Agreement to be made by either of the parties to the other shall be
            in writing, in English, and shall be made by prepaid air mail with
            return receipt addressed to the other at its address set forth
            below. Any such notice or communication may also be given by hand,
            or facsimile to the appropriate designation. Notices shall be sent:

            If to BMS, to:      Bristol-Myers Squibb Company
                                P.O. Box 4000
                                Route 206 & Province Line Road
                                Princeton, NJ 08543-4000
                                 Attention:  Senior Vice President, Exploratory
                                              Research & Drug Discovery

            If to Cubist, to:   Cubist Pharmaceuticals, Inc.
                                24 Emily Street
                                Boston, MA 02139
                                 Attention: President

            provided that if such notice or communication relates to an
            amendment to this Agreement or to any notice pursuant to section 12
            hereof, a copy shall also be sent to:

            If to BMS, to:      Attention: Vice President & Senior Counsel,
                                Pharmaceutical Research Institute and
                                Worldwide Strategic Business Planning.

            If to Cubist, to:   Justin Morreale, Esq.
                                Bingham, Dana & Gould
                                150 Federal Street
                                Boston, MA 02110-1726

            Either party may by like notice specify or change an address to
            which notices and communications shall thereafter be sent. Notices
            sent by mail, facsimile or cable shall be effective upon receipt and
            notices given by hand shall be effective when delivered.

     14.5   Governing Law.  This Agreement shall be governed by the laws of the
            -------------                                                      
            State of New York, as such laws are applied to contracts entered
            into and to be performed within such state.

     14.6   Waiver.  Except as specifically provided for herein, the waiver from
            ------                                                              
            time to time by either of the parties of any of their rights or
            their failure to exercise any remedy shall not operate or be
            construed as a
<PAGE>
 
                                     -52-
 

            continuing waiver of same or of any other of such party's rights or
            remedies provided in this Agreement.

     14.7   Severability.  If any term, covenant or condition of this Agreement
            ------------                                                       
            or the application thereof to any party or circumstance shall, to
            any extent, be held to be invalid or unenforceable, then the
            remainder of this Agreement, or the application of such term,
            covenant or condition to parties or circumstances other than those
            as to which it is held invalid or unenforceable, shall not be
            affected thereby and each term, covenant or condition of this
            Agreement shall be valid and be enforced to the fullest extent
            permitted by law; and the parties hereto covenant and agree to
            renegotiate any such term, covenant or application thereof in good
            faith in order to provide a reasonably acceptable alternative to the
            term, covenant or condition of this Agreement or the application
            thereof that is invalid or unenforceable, it being the intent of the
            parties that the basic purposes of this Agreement are to be
            effectuated.

     14.8   Independent Contractors.  It is expressly agreed that Cubist and BMS
            -----------------------                                             
            shall be independent contractors and that the relationship between
            the two parties shall not constitute a partnership or agency of any
            kind. Neither Cubist nor BMS shall have the authority to make any
            statements, representations or commitments of any kind, or to take
            any action, which shall be binding on the other, without the prior
            written authorization of the party to do so.

     14.9   Counterparts.  This Agreement may be executed in two or more
            ------------                                                
            counterparts, each of which shall be deemed an original, but all of
            which together shall constitute one and the same instrument.

     14.10  Entire Agreement.  This Agreement between the parties of even date
            ----------------                                                  
            herewith set forth all of the covenants, promises, agreements,
            warranties, representations, conditions and understandings between
            the parties hereto, and supersede and terminate all prior agreements
            and understanding between the parties, with respect to the subject
            matter hereof. There are no covenants, promises, agreements,
            warranties, representations conditions or understandings, either
            oral or written, between the parties other than as set forth herein
            and therein. No subsequent alteration, amendment, change or addition
            to this Agreement shall be binding upon the parties hereto unless
            reduced to writing and signed by the respective authorized officers
            of the parties. This Agreement shall not be strictly construed
            against either party hereto. Any conflict between the terms set
            forth in the text of this Agreement and the 
<PAGE>
 
                                     -53-


            terms of any Exhibit hereto shall be resolved in favor of the text
            of this Agreement.

     14.11  No Third Party Beneficiaries.  No third party including any employee
            ----------------------------                                        
            of any party to this Agreement, shall have or acquire any rights by
            reason of this Agreement. Nothing contained in this Agreement shall
            be deemed to constitute the parties partners with each other or any
            third party.

            IN WITNESS WHEREOF, the parties have caused this Agreement to be
     executed by their duly authorized representatives.

<TABLE> 
<S>                           <C>
BRISTOL-MYERS SQUIBB          CUBIST PHARMACEUTICALS,
 COMPANY                       INC.


By:                           By:                        
   ---------------------         ---------------------
                                                      
Title:                        Title:                    
      ------------------            ------------------
                                                      
Date:                         Date:                     
     -------------------           -------------------
</TABLE> 

<PAGE>
 
                                                                   EXHIBIT 10.10

                            Confidential Treatment
 
                         SUPPLY AND SERVICES AGREEMENT

     This Supply and Services Agreement (the "Agreement") is made as of 
November 1, 1995 (the "Effective Date"), by and between Terrapin Technologies, 
- ----------
Inc., a Delaware corporation ("Terrapin") and Cubist Pharmaceuticals, Inc., a 
Delaware corporation ("Cubist").

                                   RECITALS

     WHEREAS, Terrapin possesses a library of compounds and is able to determine
the affinity of each compound versus Terrapin's reference proteins employed in 
Terrapin's proprietary TRAP(TM) technology (the "Terrapin Technology"); and 

     WHEREAS, Terrapin desires to apply the Terrapin Technology to Terrapin's 
library of compounds (the "Terrapin Library") in order to identify and provide 
Cubist with those compounds which are most likely to be active in Cubist's 
proprietary aminoacyl tRNA synthetase ("Synthetase") assays (the "Synthetase 
Assays," as more fully described below and in Exhibit A attached hereto); and

     WHEREAS, Cubist desires to compensate Terrapin for any compounds and 
chemical structures provided to Cubist by paying Terrapin a flat fee and to 
compensate Terrapin for any compounds and chemical structures selected by Cubist
for derivatization, development or commercialization by paying Terrapin 
additional amounts based on how active such compounds are in the Synthetase 
Assays, on the achievement of certain milestones and on commercial sales;

     NOW, THEREFORE, in consideration of the foregoing premises and the 
covenants set forth below, the parties hereby agree as follows:

                                   ARTICLE 1

                 SELECTION AND PROVISION OF SUPPLIED COMPOUNDS

     1.1  INITIAL COMPOUNDS.  Terrapin promptly shall select approximately 75 
compounds (the "Initial Compounds") from the Terrapin Library. The Initial 
Compounds will exhibit the maximum degree of chemical diversity from among the 
Terrapin Library, based on the 
<PAGE>
 
Terrapin Technology. Terrapin promptly shall ship the Initial Compounds to 
Cubist in approximately 500 microgram lots.

     1.2  SCREENING FOR AND REPORTING OF INITIAL COMPOUND PRIMARY SYNTHETASE 
ASSAY ACTIVITY.  Within 45 days of receipt of the Initial Compounds, Cubist 
shall (i) screen each such compound in its bacterial aminoacyl tRNA synthetase 
inhibition assays (collectively, the "Primary Bacterial Synthetase Assay"); (ii)
notify Terrapin of the IC50 in the Primary Bacterial Synthetase Assay (the 
"Primary Bacterial Synthetase Assay Activity") for each Initial Compound; within
90 days of receipt of the Initial Compounds, Cubist shall (iii) screen each such
compound in its fungal aminoacyl tRNA synthetase inhibition assays 
(collectively, the "Primary Fungal Synthetase Assay"); and (iv) notify Terrapin 
of the IC50 in the Primary Fungal Synthetase Assay (the "Primary Fungal 
Synthetase Assay Activity") for each Initial Compound.

     1.3  FIRST ADDITIONAL COMPOUNDS.  Upon receipt of the notification of the 
Initial Compound Primary Bacterial and Fungal Synthetase Assays Activity,
Terrapin promptly shall select approximately 50 compounds (the "First Additional
Compounds") from the Terrapin Library. The First Additional Compounds shall be
those compounds which Terrapin believes, in its sole discretion, exhibit the
greatest likelihood of Primary Bacterial or Fungal Synthetase Assay Activity,
based upon the Terrapin Technology and the Initial Compound Primary Bacterial
and Fungal Synthetase Assays Activity. Terrapin promptly shall ship the First
Additional Compounds to Cubist in approximately 500 microgram lots.

     1.4  SCREENING FOR AND REPORTING OF FIRST ADDITIONAL COMPOUND PRIMARY 
SYNTHETASE ASSAY ACTIVITY.  Within ******* of receipt of the First Additional 
Compounds, Cubist shall (i) screen each such compound in the Primary Bacterial 
and Fungal Synthetase Assays, and (ii) notify Terrapin of the Primary Bacterial 
and Fungal Synthetase Assay Activity for each such compound.

     1.5  SECOND ADDITIONAL COMPOUNDS.  Upon receipt of the notification of the 
First Additional Compound Primary Bacterial and Fungal Synthetase Assay 
Activity, Terrapin promptly shall select approximately 50 compounds (the "Second
Additional Compounds") from the Terrapin Library. The Second Additional 
Compounds shall be those compounds which Terrapin believes, in its sole 
discretion, exhibit the greatest likelihood of Primary Bacterial or Fungal 
Synthetase Assay Activity, based upon the Terrapin Technology and the Primary 
Bacterial and Fungal Synthetase Assay Activity of the Initial Compounds and the 
First





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<PAGE>
 
Additional Compounds. Terrapin promptly shall ship the Second Additional 
Compounds to Cubist in approximately 500 microgram lots.

     1.6  SCREENING FOR AND REPORTING OF SECOND ADDITIONAL COMPOUND ACTIVITY IN 
PRIMARY SYNTHETASE ASSAY.  Within 45 days of receipt of the Second Additional 
Compounds, Cubist shall (i) screen each such compound in the Primary Bacterial 
and Fungal Synthetase Assays, and (ii) notify Terrapin of the Primary Bacterial 
and Fungal Synthetase Assay Activity for each such compound.

     1.7  SUBSEQUENT IDENTIFICATION OF COMPOUNDS.  If, at any time after the 
provision to Cubist of the Second Additional Compounds and prior to the 
expiration or earlier termination of this Agreement pursuant to Article 7 
hereunder, Terrapin acquires compounds (the "Subsequent Compounds") which it 
believes, in its sole discretion, exhibit a significant likelihood of Primary 
Bacterial and Fungal Synthetase Assay Activity, Terrapin may ship such compounds
to Cubist in approximately 500 microgram lots, subject to any contrary 
obligations to third parties or to restrictions imposed by law. The Subsequent 
Compounds, together with the Initial Compounds, the First Additional Compounds 
and the Second Additional Compounds, collectively shall be known as the
"Supplied Compounds."

     1.8  SCREENING FOR AND REPORTING OF COMPOUND ACTIVITY IN SECONDARY 
BACTERIAL SYNTHETASE ASSAY.  Within 30 days after Cubist provides the 
notification to Terrapin required by Section 1.6 (ii) and within 30 days after 
receipt of any Subsequent Compound, Cubist shall (i) screen in secondary 
bacterial aminoacyl tRNA synthetase assays (the "Secondary Bacterial Synthetase 
Assay") Initial Compounds, First Additional Compounds, and Second Additional
Compounds whose Primary Bacterial Synthetase Assay Activity was 10 micromolar or
lower, as well as any other Supplied Compounds, including but not limited to
Subsequent Compounds, which, in the sole judgment of Cubist, show promise as
anti-infective agents against the target pathogens specified in Exhibit A, and
(ii) notify Terrapin of the IC50 for each such compound screened in the
Secondary Bacterial Synthetase Assays (the "Secondary Bacterial Synthetase Assay
Activity").

     1.9  SCREENING FOR AND REPORTING OF COMPOUND ACTIVITY IN TERTIARY 
SYNTHETASE SELECTIVITY ASSAY.  Within 30 days after Cubist provides the 
notification to Terrapin required by Section 1.6(ii) and Section 1.8(ii) and 
within 45 days after receipt of any Subsequent Compounds, Cubist shall (i) 
screen in tertiary human aminoacyl tRNA synthetase assays
<PAGE>
 
(the "Tertiary Synthetase Selectivity Assay") Initial Compounds, First
Additional Compounds, and Second Additional Compounds whose Primary Bacterial
and Fungal Synthetase Assay Activity was 10 micromolar or lower, as well as any
other Supplied Compounds, including but not limited to Subsequent Compounds,
which in the sole discretion of Cubist, show promise as antiinfective agents
against the target pathogens specified in Exhibit A, and (ii) notify Terrapin of
the IC50 for each such compound screened in the Tertiary Synthetase Selectivity
Assay (the "Tertiary Synthetase Selectivity Assay Activity").

     1.10 APPLICATION OF TERRAPIN TECHNOLOGY TO COMPOUNDS OWNED BY CUBIST. At
any time during the term of this Agreement, Cubist may send Terrapin up to 1,000
compounds owned by Cubist in approximately 2.5 mg lots, distinct from the
Terrapin Supplied Compounds. Terrapin may apply the Terrapin Technology to such
compounds to assist Terrapin in making its determinations pursuant to Sections
1.1, 1.3, 1.5, and 1.7 hereof. Within 90 days of receipt of compounds pursuant
to this Section 1.10, Terrapin shall return or destroy such compounds, as
directed in writing by Cubist. Terrapin shall not attempt to ascertain, by any
means, the chemical structure or any other information concerning any compound
supplied by Cubist under this Section 1.10, an undertaking that shall survive
for a period of 5 years following the expiration or earlier termination of this
Agreement.

     1.11 INITIAL PAYMENT. Cubist shall pay Terrapin *************************
in partial consideration of Terrapin's entering into this Agreement. This amount
shall not be subject to withholding tax or any other setoffs. Such payment shall
be due within 30 days of the Effective Date.

                            
                                   ARTICLE 2
                           
                            SHIPMENT OF COMPOUNDS 

     2.1  All deliveries pursuant to this Agreement shall be prepaid by the 
shipper.







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<PAGE>
 
                                   ARTICLE 3

             PROVISION OF CHEMICAL STRUCTURE OF ACTIVE COMPOUNDS;
                PAYMENT FOR ACTIVE COMPOUNDS SELECTED BY CUBIST


     3.1  CATEGORIZATION OF ACTIVE COMPOUNDS. Each Supplied Compound which is
screened by Cubist pursuant to subsections 1.2(i) and 1.2(iii) and exhibits
Primary Bacterial or Fungal Synthetase Activity of 10 micromolar or less shall
be known collectively as "Micromolar Compounds"; each Supplied Compound which is
screened by Cubist pursuant to subsection 1.8(i) and exhibits Secondary
Bacterial Synthetase Activity of 999 nanomolar or less for at least four (4)
bacterial pathogen synthetases shall be known as "Broad Spectrum Compounds", and
each Supplied Compound screened by Cubist pursuant to subsection 1.9(i) which
exhibits Primary Bacterial or Fungal Synthetase Activity of 999 nanomolar or
less and is at least 100-fold less potent in the Tertiary Synthetase Selectivity
Assay shall be known as "Selective Compounds". The Micromolar Compounds, the
Broad Spectrum Compounds, and the Selective Compounds shall be collectively
known as "Active Compounds".

     3.2  LIST OF ACTIVE COMPOUNDS. Simultaneously with delivery of the 
notification required by subsection 1.8 (ii), Cubist shall provide Terrapin with
a list (the "List of Active Compounds") of all Supplied Compounds received to
date and not set forth in any prior List of Active Compounds, which list shall
divide such compounds into four (4) categories: (i) Micromolar Compounds; (ii)
Broad Spectrum Compounds; (iii) Selective Compounds; and (iv) all other Supplied
Compounds.

     3.3  STRUCTURE OF ACTIVE COMPOUNDS. Within 30 days of receipt of the List 
Of Active Compounds, Terrapin shall provide Cubist with the chemical structure 
of each Active Compound on such list.

     3.4  COVENANT NOT TO REVERSE ENGINEER. Cubist will not attempt to 
ascertain, by any means, the chemical structure or any other information 
concerning any Supplied Compound unless and until Terrapin has provided the 
chemical structure of such Supplied Compound to Cubist pursuant to Section 3.3. 
Notwithstanding the foregoing, Cubist may run the Primary and Secondary 
Synthetase Assays on the Supplied Compounds. The above covenant shall survive 
for a period of 5 years following the expiration or earlier termination of this 
Agreement.














<PAGE>
 
     3.5  PAYMENT FOR ACTIVE COMPOUNDS SELECTED BY CUBIST. Within 30 days of
receipt of the chemical structures pursuant to Section 3.3 (the "Initial
Selection Period"), Cubist shall pay Terrapin in accordance with the following
schedule for Active Compounds which Cubist, at such time and in its sole
discretion, selects for Derivatization, as herinafter defined, for development
or for commercialization:

          (a)  Micromolar Compounds. Cubist shall pay Terrapin
******************** in respect of the first selected Micromolar Compound and
********************************* in respect of each additional selected
Micromolar Compound; and

          (b)  Broad Spectrum Compounds. Cubist shall pay Terrapin
******************** in respect of each selected Broad Spectrum Compound; and

          (c)  Selective Compounds. Cubist shall pay Terrapin
*********************** in respect of each selected Selective Compound.

Cubist shall pay Terrapin only one amount in respect of each Active Compound,
such amount being equal to the greatest amount payable pursuant to subsection
(a), (b), or (c) of this Section 3.5. No amounts payable pursuant to this
Section 3.5 shall be subject to withholding tax or any other setoffs. If, at any
time prior to expiration or termination of this Agreement and after the Initial
Selection Period, Cubist should, in its sole discretion, select for
Derivatization, development or commercialization any Active Compound, it shall,
within 30 days of such selection, pay Terrapin such amounts as would be due
Terrapin if such selection were made during the Initial Selection Period. It is
understood that Cubist shall not be required to select for Derivatization,
development or commercialization any of the Active Compounds, the decision as to
selection being committed to Cubist's sole discretion. Notwithstanding any other
provision of this Section 3.5, if Cubist does select at least one Active
Compound for Derivatization, development or commercialization, Cubist's total
payments to Terrapin under this Section shall not be less than 
*********************. "Derivatization" shall mean the development or
commercialization of a Derivative, as such term is defined in Section 4.2 below.
 

 




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<PAGE>
 
                                   ARTICLE 4

                OWNERSHIP OF PROPERTY; ROYALTIES AND MILESTONES

     4.1  SYNTHETASE RIGHTS TO SELECTED COMPOUNDS. Subject to the limitation of
Section 6.1, upon selection by Cubist of any Active Compound for Derivatization,
development or commercialization (and payment to Terrapin of the appropriate
amount under Section 3.5), as between Cubist and Terrapin, Cubist shall be
deemed to have all right, title and interest to that compound and Derivatives
thereof (and related intellectual property), but solely for the purpose of
developing and commercializing the compound(s) and Derivatives as anti-infective
agents. (See Section 4.2 for definition of Derivative). Notwithstanding the
foregoing, Terrapin shall retain all rights to its intellectual property for
purposes other than the Derivatization, development or commercialization of 
Active Compounds as anti-infective agents.

     4.2  ROYALTIES AND OTHER CONSIDERATION TO TERRAPIN. In the event that
Cubist shall sell commercially as an anti-infective agent any Active Compound
(or Derivative of an Active Compound), Cubist shall pay Terrapin a ******** of
Cubist's worldwide Net Sales of such compound (gross sales, less discounts,
allowances, rebates, etc. actually granted). Cubist shall have the right to
license any such compound to one or more third parties, in which case Terrapin
shall receive a ****************** Such royalty payments to Terrapin will be
made within twenty-one days of the close of each quarter, or in the case of
Terrapin's share of royalties received by Cubist from Cubist's licensee(s),
within ten days after Cubist's receipt of such royalties, whichever is later.
Terrapin shall also receive ************ of any Performance Payment and Contract
Signature Payments that Cubist receives from its licensee(s), said payments by
Cubist to be made within ten days after Cubist receives such payment from its
licensee(s). As used herin, "Contract Signature Payment" means license fees and
similar up-front payments and Technology Premium Equity Payments, but does not
include reimbursement of research and development costs. Technology Premium
Equity Payments means *************************.






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<PAGE>
 
***************************************** As used herein, "Performance Payments"
means a payment made by Cubist's licensee(s) to Cubist for fulfillment of a
designated developmental or regulatory milestone. As used herein, "Derivative"
means any compound which, but for an Active Compound or information contained in
an Active Compound, would not have been identified, discovered, synthetized or
developed by Cubist, sublicensees or agent, at the time such compound actually
was identified, synthesized or developed by Cubist, sublicensees or agent.

     4.3  REPORTS TO TERRAPIN. If Cubist selects an Active Compound for further 
Derivatization, development or commercialization, it shall provide Terrapin with
developmental progress reports on a semiannual basis in July and January of each
calendar year. In addition, any royalty or share of Performance Payments or 
Contract Signature Payments that is made to Terrapin under Section 4.2 shall be 
accompanied by a report in sufficient detail to permit Terrapin to ascertain the
basis for such payment. Cubist shall permit Terrapin or its authorized 
accounting representative to audit Cubist's relevant records once annually to 
permit Terrapin to verify that the required payments have been made to Terrapin 
under this Agreement.

     4.4  EXCLUSIVITY. Without limitation as to the provisions of Section 6.1,
below, during the term of this Agreement, Terrapin will not knowingly provide
any compounds from the Terrapin Library or any information derived from such
compounds, including, but not limited to, the chemical structure of such
compounds, to third parties for use in the discovery and development of products
for the treatment of infectious diseases based on the Synthetase Assays, except
insofar as such Synthetase Assays become generally available to the public. No
compound selected by Cubist for further Derivatization, development and
commercialization pursuant to Section 3.5 shall be knowlingly supplied by
Terrapin to a third party for use as an anti-infective agent at any time during
the term of this Agreement or for 5 years following its expiration or earlier
termination.

     4.5  CUBIST TO HAVE EXCLUSIVE CONTROL OVER DEVELOPMENT AND 
COMMERCIALIZATION. It is understood that Cubist shall have complete control over
the development and commercialization of any Active Compound that it selects 
from the Supplied Compounds (and the Derivatives), including but not limited to 
decisions concerning the allocation of resources to such project and whether or 
not to continue with or cease the development or commercialization of any such 
compound or Derivative; provided, however, if Cubist ceases the development or 
commercialization of such compound or Derivative it shall promptly notify







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<PAGE>
 
Terrapin of such cessation and the last sentence of Section 4.4 shall not be 
applicable to such compound.

                                   ARTICLE 5

                           CONFIDENTIAL INFORMATION

     5.1  NONDISCLOSURE OBLIGATIONS. Anything in this Agreement to the contrary
notwithstanding but subject to the provisions of Section 4.1, for 5 years
following the expiration or termination of this Agreement any and all knowledge,
know-how, screening results, compound structures, practices, processes or other
information received by one party to this Agreement (the "Receiving Party") from
the other party to this Agreement (the "Disclosing Party") pursuant to Article 1
or Article 3 hereof (hereinafter referred to as "Confidential Information")
shall be received and maintained by the Receiving Party in strict confidence and
shall not be disclosed to any third party. For purposes of the preceding
sentence, information derived by Terrapin from the compounds sent to Terrapin
pursuant to Section 1.10 hereof shall be deemed to be Confidential Information
received by Terrapin. Furthermore, for 5 years following the expiration or
termination of this Agreement the Receiving Party shall not use said
Confidential Information for any purpose other than those purposes specified in
this Agreement. The Receiving Party may disclose Confidential Information to
employees requiring access thereto for the purposes of this Agreement; provided,
however, that prior to making any such disclosures, each such employee shall be
apprised of the duty and obligation to maintain Confidential Information in
confidence and not to use such information for any purpose other than in
accordance with the terms and conditions of this Agreement. The Receiving Party
agrees to take all steps necessary to ensure that the Confidential Information
received will be maintained in confidence including such steps as it takes to
prevent the disclosure of its own proprietary and confidential information of
like character. Each party agrees that this Agreement shall be binding upon its
affiliates, and upon the employees and associates of such party and its
affiliates. Each party will take all steps necessary to ensure that its
affiliates, employees and associates will comply with the terms and conditions
of this Agreement.

     5.2  EXCEPTIONS. The nondisclosure and non-use obligations of Section 5.1 
hereof shall not apply to Confidential Information which the Receiving Party can
establish by competent written proof:
<PAGE>
 

          (a)  at the time of disclosure is in the public domain;

          (b)  after disclosure, becomes part of the public domain by
publication or otherwise, except by (i) breach of this Agreement by the
Receiving Party or (ii) disclosure by any person or affiliate company to whom
Confidential Information was disclosed under Section 5.1 hereof;

          (c)  was in the Receiving Party's possession at the time of disclosure
by the Disclosing Party;

          (d)  is received by the Receiving Party from a third party who has the
lawful right to disclose the Confidential Information and who shall not have
obtained the Confidential Information either directly or indirectly from the
Disclosing Party; or

          (e)  is disclosed as required by law or regulation.

     In the event that Confidential Information is required to be disclosed
pursuant to subsection (e), the Receiving Party shall notify the Disclosing
Party to allow the Disclosing Party to assert whatever exclusions or exemptions
may be available to it under such law or regulation.

                                   ARTICLE 6

                           DISCLAIMER OF WARRANTIES

     6.1  THE SUPPLIED COMPOUNDS AND THE CHEMICAL STRUCTURES OF ACTIVE COMPOUNDS
ARE BEING SUPPLIED TO CUBIST WITH NO WARRANTIES OF ANY KIND, EXPRESS OR IMPLIED,
INCLUDING ANY WARRANTY OF MERCHANT ABILITY OR FITNESS FOR A PARTICULAR PURPOSE
OR THAT THEY ARE FREE FROM THE RIGHTFUL CLAIM OF ANY THIRD PARTY, BY WAY OF
INFRINGEMENT OR THE LIKE. TERRAPIN MAKES NO REPRESENTATIONS THAT THE USE OF THE
SUPPLIED COMPOUNDS OR THE CHEMICAL STRUCTURES OF ACTIVE COMPOUNDS AND
POTENTIALLY ACTIVE COMPOUNDS WILL NOT INFRINGE ANY PATENT OR PROPRIETARY RIGHTS
OF ANY THIRD PARTIES.
<PAGE>
 
                                   ARTICLE 7

                               TERM; TERMINATION

     7.1  TERM. This Agreement shall become effective as of the date first 
herein above written and unless earlier terminated as hereinafter provided, 
shall continue in force for a period of *************** after the same, 
provided, however, that the provisions of Sections 1.10, 3.4, 4.2, 4.3 and 4.4 
and Article 5 hereof shall remain in effect as provided for therin. This 
Agreement may be extended from time to time by mutual agreement of the parties 
hereto.

     7.2  TERMINATION FOR DEFAULT. In the event that either party to this 
Agreement shall be in default of any of its material obligation hereunder and
shall fail to remedy such default within thirty (30) days after receipt of
written notice thereof, the party not in default shall have the option of
terminating this Agreement by giving written notice thereof, notwithstanding
anything to the contrary contained in this Agreement.

     7.3  EARLY TERMINATION. If Cubist makes no selection of Supplied Compounds 
for Derivatization, development or commercialization following completion of the
program described in Article 1, either party may at any time thereafter
terminate this Agreement upon thirty (30) days written notice for any reason.

     7.4  EFFECT OF TERMINATION. Termination of this Agreement shall not affect
the rights and obligations of the parties which accrued prior to the effective 
date of termination, including, but not limited to, any amounts due and owing 
under Sections 3.5 and 4.2 of this Agreement.

                                   ARTICLE 8

                                MISCELLANEOUS

     8.1  USE LIMITATION. The parties acknowledge and agree that the Supplied 
Compounds may have biological and/or chemical properties that are unpredictable 
and unknown at the time of transfer to Cubist, that they are to be used with 
caution and prudence, and are not to be used for testing in or treatment of 
humans.

     8.2  INDEPENDENT CONTRACTORS. The parties shall perform their obligations 
under this Agreement as independent contractors and nothing






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<PAGE>
 
contained in this Agreement shall be construed to be inconsistent with such 
relationship status. This Agreement shall not constitute, create or in any way 
be interpreted as a joint venture or partnership of any kind.

     8.3  ENTIRE AGREEMENT; AMENDMENT. This Agreement sets forth all the 
covenants, promises, agreements, warranties, representations, conditions and 
understandings between the parties hereto and supersedes and terminates all 
prior agreements and understanding between the parties hereto, and there are no 
covenants, promises, agreements, warranties, representations, conditions or 
understandings, either oral or written, between the parties hereto other than as
set forth herein. No subsequent alteration, amendment, change or addition to
this Agreement shall be binding upon the parties hereto unless reduced to 
writing and signed by the respective authorized officers of the parties hereto.

     8.4  HEADINGS. The headings used in this Agreement are for convenience of 
reference only and are not intended to be a part of or to affect the meaning or 
interpretation of this Agreement.

     8.5  FORCE MAJEURE. Any delays in performance by any party under this 
Agreement shall not be considered a breach of this Agreement if and to the 
extent caused by occurrences beyond the reasonable control of the party
affected, including by not limited to, acts or God, embargoes, governmental
restrictions, strikes or other concerted acts of workers, fire, flood,
explosion, riots, wars, civil disorder, rebellion or sabotage. The party
suffering such occurrence shall immediately notify the other party and any time
for performance hereunder shall be extended by the actual time of delay caused
by the occurrence.

     8.6  SEVERABILITY. If any term, condition or provision of this Agreement is
held to be unenforceable for any reason, it shall, if possible, be interpreted 
rather than voided, in order to achieve the intent of the parties to this
Agreement to the extent possible. In any event, all other terms, conditions and
provisions of this agreement shall be deemed valid and enforceable to the full
extent.

     8.7  WAIVER. None of the terms, covenants, and conditions of this Agreement
can be waived except by the written consent of the party waiving compliance.




 
<PAGE>
 
     8.8  APPLICABLE LAW. This Agreement shall be governed by the laws of the 
state of California without regard to choice of law provisions.

     IN WITNESS WHEREOF, the parties have by duly authorized persons, executed 
this Agreement, as of the date first above written.


Cubist Pharmaceuticals, Inc.                 Terrapin Technologies, Inc.



By: /s/ S.M. Rocklage                        By: /s/ Clifford Arent
   --------------------------                   ----------------------------


Title: PRESIDENT & CEO                       Title: PRESIDENT & CEO
       ----------------------                       ------------------------

<PAGE>
 
                                                                   EXHIBIT 10.12

                            Confidential Treatment
 
                  [LETTERHEAD OF CUBIST PHARMACEUTICALS, INC]


January 18, 1996


Pharm-Eco Laboratories, Inc.
128 Spring Street
Lexington, Massachusetts 02173

Attention:          E. Lee Piver, Vice President
                    Sales

Dear Mr. Piver:

Cubist Pharmaceuticals, Inc. ("Cubist") is interested in obtaining chemical 
compounds from Pharm-Eco for screening in antibacterial and antifungal assays.  
Cubist proposes that Pharm-Eco provide Cubist samples of compounds derived from 
Pharm-Eco's proprietary combinatorial technology ("Pharm-Eco Compounds") and 
samples of compounds of interest which Pharm-Eco has acquired under license from
university researchers ("University Compounds") for a program of primary 
screening and evaluation by Cubist to determine whether such compounds may be 
effective as antimicrobial agents ("Program").

The Program will operate as follows:

1.   Information to be Supplied. In addition to providing the samples Pharm-Eco 
     --------------------------
will also provide to Cubist any information which Pharm-Eco may have as to 
whether the compounds:

     a.   are considered to be new;
     b.   have been previously screened for biological activity (if so, Pharm-
          Eco will provide any summary it may have of the results of such
          screening);
     c.   were synthesized or isolated under Government sponsorship;
     d.   are subject to the rights of any other party; and
     e.   may be made, used and sold under license (if so, Pharm-Eco will also
          indicate the terms under which such any license rights may be
          available to Cubist).

2.   Screening Method.  Cubist shall choose the appropriate biological screening
     ----------------
for each compound.

3.   Safety.  Pharm-Eco shall provide to Cubist any written safety information 
     ------
or Material Safety Data Sheets which Pharm-Eco may have concerning the 
compounds, in order to assist Cubist to take appropriate precautions in the 
screening of the compounds.  However, Cubist shall bear sole responsibility for 
safety protection in performance of the Program.

<PAGE>
 
4.   Payment.  Within 30 days of receipt of the compounds, Cubist shall pay 
     -------
Pharm-Eco in accordance with the following schedule:

     a.   University Compounds: ******************************
     b.   Pharm-Eco Compounds: ************************

All deliveries pursuant to this Agreement shall be prepaid by the shipper.

5.   Compounds of No Interest to Cubist. If, after completion of its evaluation 
     ----------------------------------
of a particular compound, Cubist determines that it does not have further 
interest in that compound, Cubist will immediately notify Pharm-Eco and provide 
Pharm-Eco with a summary of the primary screening results for such compound. 
Such summary may then be used by Pharm-Eco in any manner it deems desirable.

6.   Compounds of Interest to Cubist. If, after completion of its evaluation of 
     -------------------------------
a particular compound, Cubist determines that it does have further interest in 
that compound, Cubist will immediately notify Pharm-Eco and the parties will 
thereupon enter into good faith efforts for at least ninety (90) days to 
negotiate an agreement to conduct a joint drug discovery program related to that
compound and analogs and homologs thereof, after which time, if an agreement has
not been executed, either party may abandon the negotiations.

7.   No Rights Transferred. Except as expressly provided herein, neither party 
     ---------------------
shall be deemed to have transferred to the other any rights in either compounds 
or screening results.

8.   No Analysis. Except as expressly provided herein, Cubist agrees that it 
     -----------
will attempt to ascertain by any means the chemical structure or other 
information concerning any compound received from Pharm-Eco hereunder, unless 
and until the parties have executed a joint drug discovery agreement permitting 
such analysis.

9.   Confidentiality. Except as expressly provided herein, any information 
     ---------------
disclosed by either party to the other in accordance with this Agreement, which 
shall include, but is not limited to, samples of compounds and their chemical 
nature ("Information"), shall be maintained in secrecy and each party will use 
all reasonable diligence to prevent disclosure except to necessary personnel and
to affiliates and consultants, who agree to be bound by this Disclosure 
Agreement. Pharm-Eco's and Cubist's obligations under this Agreement shall be 
limited to a period of five (5) years from receipt of such Information. Neither 
Pharm-Eco nor Cubist shall have any obligation of confidentiality with respect 
to any Information that can be reasonably shown to be:

     a.   in the public domain by use and/or publication at the time of its
          receipt from the disclosing party; or developed independently and
          without knowledge of Information received from the disclosing party;
          or

     b.   already known to be in its possession prior to receipt from the
          disclosing party; or

     c.   properly obtained by recipient from a third party with a valid legal
          right to disclose such Information and such third party is not under a
          confidentiality obligation to the disclosing party.




                      *Confidential treatment requested:
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<PAGE>
 
Any Information received by either party from the other shall be promptly 
returned, upon request, except that each party may retain one copy of all 
written Information in its confidential files, solely for record purposes.

10.  Compliance with Government Requirements.  With regard to compounds 
     ---------------------------------------
submitted and screened pursuant to the Program, Cubist will comply with
applicable requirements of a sponsoring governmental or other agency, if any,
under which the compounds were synthesized or isolated.

11.  No Publicity.  Except as expressly provided herein, neither party may 
     ------------
disclose the nature of this Agreement nor any activity hereunder nor use the 
name of the other party in any publication or other disclosure without the prior
written permission of the other party.

12.  Governing Law.  This Agreement shall be construed and interpreted in 
     -------------
accordance with the laws of the Commonwealth of Massachusetts.

13.  Term and Termination.  This proposal shall become effective as an 
     --------------------
agreement (the "Agreement") when signed and dated by Pharm-Eco. The term of the 
Program shall be for three (3) years from the effective date; provided, 
however, that either party may terminate the Program at will upon three (3) 
months prior written notice to the other party. Termination of the Program shall
not terminate the obligations imposed on the parties under Paragraphs 4, 8 and 
9.

                                        Sincerely Yours,
                                        Cubist Pharmaceuticals, Inc.


                                        By: /s/ Nancy M. Gray
                                           ------------------------------
                                        Nancy M. Gray, Ph.D.
                                        Vice President, Corporate Development

Accepted and Agreed to:
Pharm-Eco Laboratories, Inc.


By:       /s/ David J. Wade
      -------------------------
              David J. Wade
Title:        President
      -------------------------

Date:       January 18, 1996
      -------------------------

<PAGE>
 
                                                                      EXHIBIT 11
 
                          CUBIST PHARMACEUTICALS, INC.
 
                        COMPUTATION OF INCOME PER SHARE
 
                     AS OF DECEMBER 31, 1993, 1994 AND 1995
                     AND THE SIX MONTHS ENDED JUNE 30, 1996
 
<TABLE>   
<CAPTION>
                                                       HISTORICAL    PRO FORMA
                                                       -----------  -----------
<S>                                                    <C>          <C>
Beginning Balance 1/1/93..............................     444,899
Issuance of Common Stock..............................      36,751
Issuance of Cheap Stock...............................     460,656
Issuance of Preferred Stock...........................           0
                                                       -----------
  Weighted Average Shares at 12/31/93.................     942,306
  Net Loss............................................ $(1,687,894)
  Net Loss per Share..................................      $(1.79)
                                                       ===========
Beginning Balance 1/1/94..............................     546,864
Issuance of Common Stock..............................      85,661
Issuance of Cheap Stock...............................     460,656
Issuance of Preferred Stock...........................           0
                                                       -----------
  Weighted Average Shares at 12/31/94.................   1,093,181
  Net Loss............................................ $(4,813,035)
  Net Loss per Share..................................      $(4.40)
                                                       ===========
Beginning Balance 1/1/95..............................     910,030    3,729,083
Issuance of Common Stock..............................      76,228       76,228
Issuance of Cheap Stock...............................     460,656      460,656
Issuance of Preferred Stock...........................           0    1,631,673
                                                       -----------  -----------
  Weighted Average Shares at 12/31/95.................   1,446,914    5,897,640
  Net Loss............................................ $(5,396,006) $(5,396,006)
  Net Loss per Share..................................      $(3.73)      $(0.91)
                                                       ===========  ===========
Beginning Balance 1/1/96..............................   1,016,666    5,981,120
Issuance of Common Stock..............................      (5,760)      (5,760)
Issuance of Cheap Stock...............................     460,656      460,656
Issuance of Preferred Stock...........................           0       13,266
                                                       -----------  -----------
  Weighted Average Shares at 6/30/96..................   1,471,562    6,449,282
  Net Loss............................................ $(2,073,213) $(2,073,213)
  Net Loss per Share..................................      $(1.41)      $(0.32)
                                                       ===========  ===========
</TABLE>    

<PAGE>
 
                                                                   EXHIBIT 23.2
 
  This is the form of the consent which will be issued upon effectiveness of
the stock split described in Note M to the financial statements.
 
                                          /s/ Coopers & Lybrand L.L.P.
                                          Coopers & Lybrand L.L.P.
 
Boston, Massachusetts
   
September 17, 1996     
 
                      CONSENT OF INDEPENDENT ACCOUNTANTS
 
  We consent to the inclusion in this registration statement on Form S-1 of
our report dated January 12, 1996, except as to the information in Notes L and
M for which the date is     , 1996, on our audits of the financial statements
of Cubist Pharmaceuticals, Inc. We also consent to the references to our firm
under the captions "Selected Financial Data" and "Experts."
 
Boston, Massachusetts
    , 1996

<PAGE>
 
                                                                   EXHIBIT 23.3
 
              HAMILTON, BROOK, SMITH & REYNOLDS, P.C. LETTERHEAD
 
 
          CONSENT OF SPECIAL COUNSEL FOR CUBIST PHARMACEUTICALS, INC.
 
  We hereby consent to the reference to our name, and to the statements with
respect to us, in Cubist Pharmaceuticals, Inc.'s Registration Statement on
Form S-1 and the Prospectus relating thereto under the caption "Experts."
 
                                          Hamilton, Brook, Smith & Reynolds,
                                           P.C.
 
                                                   /s/ David E. Brook
                                          By: _________________________________
                                                     DAVID E. BROOK
   
Dated: September 17, 1996     

<TABLE> <S> <C>

<PAGE>
 
<ARTICLE> 5
<LEGEND>
THIS SCHEDULE CONTAINS SUMMARY FINANCIAL INFORMATION EXTRACTED FROM CUBIST FORM
S-1 AND IS QUALIFIED IN ITS ENTIRETY BY REFERENCE TO SUCH FINANCIAL STATEMENTS.
</LEGEND>
       
<S>                             <C>                     <C>
<PERIOD-TYPE>                   YEAR                   6-MOS
<FISCAL-YEAR-END>                          DEC-31-1995             JUN-30-1996
<PERIOD-START>                             JAN-01-1995             JAN-01-1996
<PERIOD-END>                               DEC-31-1995             JUN-30-1996
<CASH>                                       2,049,555               4,732,273
<SECURITIES>                                 1,006,569                       0
<RECEIVABLES>                                  988,000               1,915,000         
<ALLOWANCES>                                         0                       0
<INVENTORY>                                          0                       0
<CURRENT-ASSETS>                                66,996                 734,086
<PP&E>                                       3,834,953               4,171,086
<DEPRECIATION>                               1,056,802               1,368,476
<TOTAL-ASSETS>                               7,047,842              10,355,229
<CURRENT-LIABILITIES>                          896,307               2,358,690
<BONDS>                                      1,838,550               1,833,138
                                0                       0
                                     34,751                  37,568
<COMMON>                                         1,017                   1,006
<OTHER-SE>                                   4,859,005               6,751,637
<TOTAL-LIABILITY-AND-EQUITY>                 7,047,842              10,355,229
<SALES>                                              0                       0
<TOTAL-REVENUES>                             1,271,333               2,046,653
<CGS>                                                0                       0
<TOTAL-COSTS>                                        0                       0
<OTHER-EXPENSES>                             6,673,389               4,056,195
<LOSS-PROVISION>                                     0                       0
<INTEREST-EXPENSE>                             (6,050)                  63,671
<INCOME-PRETAX>                            (5,396,006)             (2,073,213)
<INCOME-TAX>                                         0                       0
<INCOME-CONTINUING>                        (5,396,006)             (2,073,213)
<DISCONTINUED>                                       0                       0
<EXTRAORDINARY>                                      0                       0
<CHANGES>                                            0                       0
<NET-INCOME>                               (5,396,006)             (2,073,213)
<EPS-PRIMARY>                                    (.91)<F1>               (.32)<F1>
<EPS-DILUTED>                                        0                       0
<FN>
<F1>Computed on a pro forma basis as described in Note B of the Notes to the
Financial Statements.
</FN>
        

</TABLE>


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