ENTREMED INC
S-1/A, 1996-06-07
PHARMACEUTICAL PREPARATIONS
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<PAGE>
   
      AS FILED WITH THE SECURITIES AND EXCHANGE COMMISSION ON JUNE 7, 1996
    
 
   
                                                       REGISTRATION NO. 333-3536
    
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                       SECURITIES AND EXCHANGE COMMISSION
                             WASHINGTON, D.C. 20549
                           --------------------------
   
                                AMENDMENT NO. 2
                                       TO
                                    FORM S-1
    
                             REGISTRATION STATEMENT
                                     UNDER
                           THE SECURITIES ACT OF 1933
                            ------------------------
                                 ENTREMED, INC.
             (Exact name of Registrant as specified in its charter)
 
<TABLE>
<S>                              <C>                            <C>
           DELAWARE                          8071                  58-1959440
       (State or other           (Primary standard industrial   (I.R.S. employer
jurisdiction of incorporation)   classification code number)     identification
                                                                    number)
</TABLE>
 
                      9610 MEDICAL CENTER DRIVE, SUITE 200
                           ROCKVILLE, MARYLAND 20850
                                 (301) 217-9858
   (Address and telephone number of Registrant's principal executive offices)
 
                             JOHN W. HOLADAY, PH.D.
                CHAIRMAN, PRESIDENT AND CHIEF EXECUTIVE OFFICER
                                 ENTREMED, INC.
                      9610 MEDICAL CENTER DRIVE, SUITE 200
                           ROCKVILLE, MARYLAND 20850
                                 (301) 217-9858
           (Name, address and telephone number of agent for service)
                           --------------------------
 
                                   COPIES TO:
 
<TABLE>
<S>                                       <C>
           JILL COHEN, ESQ.                       ROBERT H. WERBEL, ESQ.
 Bachner, Tally, Polevoy & Misher LLP         Werbel McMillin & Carnelutti,
          380 Madison Avenue                    A Professional Corporation
       New York, New York 10017                      711 Fifth Avenue
            (212) 687-7000                       New York, New York 10022
                                                      (212) 832-8300
</TABLE>
 
                           --------------------------
 
          APPROXIMATE DATE OF COMMENCEMENT OF PROPOSED SALE TO 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, please check the following box. / /
 
    If  this Form  is filed  to register  additional securities  for an offering
pursuant to Rule 462(b) under the Securities Act, please check the following box
and list  the  Securities  Act  registration statement  number  of  the  earlier
registration statement for the same offering. / /
 
    If  this Form  is a post-effective  amendment filed pursuant  to Rule 462(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. /X/
                           --------------------------
 
                        CALCULATION OF REGISTRATION FEE
 
   
<TABLE>
<CAPTION>
                                                 AMOUNT TO      PROPOSED MAXIMUM  PROPOSED MAXIMUM
           TITLE OF EACH CLASS OF                    BE          OFFERING PRICE      AGGREGATE         AMOUNT OF
        SECURITIES TO BE REGISTERED            REGISTERED (1)    PER SHARE (2)     OFFERING PRICE   REGISTRATION FEE
<S>                                           <C>               <C>               <C>               <C>
Shares of Common Stock, $.01 par value......     4,025,000           $16.00         $64,400,000        $22,207(3)
</TABLE>
    
 
   
(1) Includes 480,000 shares subject to the Underwriters' over-allotment option.
    
(2) Estimated solely for purposes of calculating the registration fee.
   
(3) Previously paid.
    
                           --------------------------
 
    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>
                                 ENTREMED, INC.
                             CROSS-REFERENCE SHEET
                   PURSUANT TO ITEM 501(B) OF REGULATION S-K
 
<TABLE>
<CAPTION>
ITEM AND CAPTION                                                                 LOCATION IN PROSPECTUS
- ----------------------------------------------------------------  -----------------------------------------------------
<C>        <S>                                                    <C>
       1.  Forepart of Registration Statement and Outside Front
            Cover Page of Prospectus............................  Outside Front Cover page
       2.  Inside Front and Outside Back Cover Pages of
            Prospectus..........................................  Front and Outside Back Cover Pages
       3.  Summary Information and Risk Factors.................  Prospectus Summary; Risk Factors; Financial
                                                                   Statements
       4.  Use of Proceeds......................................  Prospectus Summary; Use of Proceeds
       5.  Determination of Offering Price......................  Outside Front Cover Page; Risk Factors; Underwriting
       6.  Dilution.............................................  Risk Factors; Dilution
       7.  Selling Security Holders.............................  *
       8.  Plan of Distribution.................................  Outside Front Cover Page; Underwriting
       9.  Description of Securities to be Registered...........  Outside Front Cover Page; Description of Capital
                                                                   Stock
      10.  Interests of Named Experts and Counsel...............  Legal Matters; Experts
      11.  Information With Respect to the Registrant...........  Prospectus Summary; Risk Factors; The Company;
                                                                   Capitalization; Selected Financial Data;
                                                                   Management's Discussion and Analysis of Financial
                                                                   Condition and Results of Operations; Business;
                                                                   Management; Certain Transactions; Principal
                                                                   Stockholders; Financial Statements
      12.  Disclosure of Commission Position on Indemnification
            for Securities Act Liabilities......................  *
</TABLE>
 
- ------------------------
* Not applicable.
<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.
<PAGE>
   
                   SUBJECT TO COMPLETION, DATED JUNE 7, 1996
    
PROSPECTUS
   
                                3,200,000 SHARES
    
 
                              [LOGO]
 
                                  COMMON STOCK
                                ----------------
 
   
    All of  the  shares of  Common  Stock, par  value  $.01 per  share  ("Common
Stock"),  offered  hereby are  being sold  by EntreMed,  Inc. (the  "Company" or
"EntreMed"). Prior to  this offering, there  has been no  public market for  the
Common Stock of the Company. It is currently anticipated that the initial public
offering  price will be between $14.00  and $16.00 per share. See "Underwriting"
for a discussion  of the  factors to be  considered in  determining the  initial
public  offering price. The  Common Stock has  been approved for  listing on the
Nasdaq National Market under the symbol "ENMD."
    
 
   
    Bristol-Myers Squibb Company, a party  to a collaboration with the  Company,
has agreed to purchase from the Company in a private placement on the closing of
this  offering $5,000,000 of  Common Stock at the  initial public offering price
(333,333 shares, assuming an initial public offering price of $15.00 per  share)
(the "BMS Shares").
    
                            ------------------------
 
  THE SHARES OF COMMON STOCK OFFERED HEREBY INVOLVE A HIGH DEGREE OF RISK AND
         SUBSTANTIAL DILUTION. SEE "RISK FACTORS" COMMENCING ON PAGE 6.
                             ---------------------
 
THESE  SECURITIES HAVE NOT  BEEN APPROVED OR DISAPPROVED  BY THE SECURITIES AND
 EXCHANGE  COMMISSION  OR  ANY  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>
                                                                UNDERWRITING
                                                                DISCOUNTS AND     PROCEEDS TO
                                              PRICE TO PUBLIC  COMMISSIONS (1)    COMPANY (2)
<S>                                           <C>              <C>              <C>
Per Share...................................         $                $                $
Total (3)...................................         $                $                $
</TABLE>
 
(1) The Company has agreed to reimburse the Representatives of the  Underwriters
    for  certain  expenses  incurred  in connection  with  the  offering  and to
    indemnify  the   Underwriters   against   certain   liabilities,   including
    liabilities   under   the  Securities   Act   of  1933,   as   amended.  See
    "Underwriting."
 
(2) Before deducting expenses of the  offering payable by the Company  estimated
    at  $       ,  including reimbursement of expenses of the Underwriters of up
    to $200,000.
 
   
(3) The Company has granted the Underwriters  a 30-day option to purchase up  to
    480,000  additional shares of Common Stock  on the same terms and conditions
    as set forth herein, solely to cover over-allotments, if any. If such option
    is exercised in full, the total Price to Public, Underwriting Discounts  and
    Commissions,  and Proceeds to Company  will be $            ,  $         and
    $         , respectively. See "Underwriting."
    
                            ------------------------
 
    The shares of Common Stock are offered by the several Underwriters,  subject
to prior sale, when, as and if delivered to and accepted by them, and subject to
the  right of the  Underwriters to reject any  order in whole or  in part. It is
expected that delivery of  the certificates representing  such shares of  Common
Stock  will be made on or  about               , 1996  at the offices of Allen &
Company Incorporated, 711 Fifth Avenue, New York, New York 10022.
                            ------------------------
 
ALLEN & COMPANY
          INCORPORATED
                            DILLON, READ & CO. INC.
 
                                                          VOLPE, WELTY & COMPANY
 
                THE DATE OF THIS PROSPECTUS IS            , 1996
<PAGE>
                            ANGIOGENESIS AND CANCER
 
   
                 [PHOTO]                                 [PHOTO]
    
 
                                     TUMOR
 
                                  ANGIOGENESIS
 
                                  BLOOD VESSEL
 
    Angiogenesis is  the fundamental  process  by which  new blood  vessels  are
formed.  In  these  illustrations, cancer  cells  stimulate  angiogenesis, which
provides the blood  supply that  nourishes the  tumor and  supports its  growth.
EntreMed  believes  that  antiangiogenic products,  which  inhibit  the abnormal
growth of  blood  vessels,  may have  significant  advantages  over  traditional
therapies  for cancer. The Company  is currently developing several angiogenesis
inhibitors.
 
    All of the  Company's product candidates  are in the  development stage  and
require further research, development, testing and regulatory clearances.
 
                            ------------------------
 
    IN  CONNECTION WITH THIS OFFERING, THE UNDERWRITERS MAY OVER-ALLOT OR EFFECT
TRANSACTIONS WHICH STABILIZE OR MAINTAIN THE MARKET PRICE OF THE COMMON STOCK AT
A LEVEL  ABOVE THAT  WHICH MIGHT  OTHERWISE  PREVAIL IN  THE OPEN  MARKET.  SUCH
STABILIZING, IF COMMENCED, MAY BE DISCONTINUED AT ANY TIME.
 
    The  Company  intends  to  furnish  its  stockholders  with  annual  reports
containing audited  financial statements  audited by  its independent  certified
public accountants.
<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. UNLESS THE CONTEXT  INDICATES OTHERWISE, THE INFORMATION IN
THIS PROSPECTUS (I) DOES  NOT GIVE EFFECT TO  THE EXERCISE OF THE  UNDERWRITERS'
OVER-ALLOTMENT  OPTION  AND (II)  GIVES  RETROACTIVE EFFECT  TO  A TWO-FOR-THREE
REVERSE STOCK SPLIT OF THE COMMON STOCK EFFECTED IN APRIL 1996 AND THE AUTOMATIC
CONVERSION OF THE 3,000,000 OUTSTANDING SHARES OF THE COMPANY'S PREFERRED  STOCK
INTO  2,000,000 SHARES OF COMMON STOCK EFFECTIVE ON THE DATE OF THIS PROSPECTUS.
SEE "CAPITALIZATION," "DESCRIPTION  OF CAPITAL STOCK"  AND NOTE 13  OF NOTES  TO
FINANCIAL  STATEMENTS. INVESTORS  SHOULD CAREFULLY CONSIDER  THE INFORMATION SET
FORTH UNDER THE HEADING "RISK FACTORS."
    
 
                                  THE COMPANY
 
    EntreMed  is  engaged   primarily  in  the   research  and  development   of
biopharmaceutical  products that address the role  of blood and blood vessels in
the prevention and treatment  of a broad range  of diseases. The Company's  core
technologies  include (i) an antiangiogenesis program focused on the development
of proprietary products  intended to inhibit  the abnormal growth  of new  blood
vessels  associated with cancer and certain causes of blindness and (ii) a blood
cell permeation device  designed to enhance  the ability of  red blood cells  to
deliver  oxygen to  organs and  tissues and  which may  also be  used to deliver
drugs, genes  or  other therapeutic  agents  that otherwise  would  not  readily
diffuse through blood cell membranes.
 
    Angiogenesis  is  the fundamental  process by  which  new blood  vessels are
formed  and  primarily  occurs  during  the  first  three  months  of  embryonic
development.  Except  for wound  healing and  certain reproductive  processes in
women, angiogenesis  is otherwise  generally associated  with several  diseases,
including  cancer and  certain causes  of blindness.  The Company  believes that
antiangiogenic products, which inhibit the abnormal growth of blood vessels, may
have significant advantages over traditional  therapies for these diseases.  The
Company  is  currently  developing  several  angiogenesis  inhibitors, including
thalidomide and its chemical analogs and Angiostatin-TM-, a protein produced  by
the  body.  The Company  is also  applying its  expertise in  the role  of blood
function to  the development  of  a blood  cell  permeation device  designed  to
enhance the oxygen releasing capabilities of red blood cells. Organs and tissues
in  the body require oxygen to function  properly and oxygen deficiency may lead
to tissue damage or death.
 
   
    In  December   1995,   the   Company  and   Bristol-Myers   Squibb   Company
("Bristol-Myers")  entered  into a  collaboration  to develop  and commercialize
certain  antiangiogenesis   therapeutics.   This  collaboration   provides   for
Bristol-Myers  to  fund  Company  research, provide  milestone  payments  to the
Company and pay  the Company royalties  on net sales  of any products  developed
under  the collaboration.  In addition,  Bristol-Myers made  a $6,500,000 equity
investment in the  Company and agreed  to make an  additional $5,000,000  equity
investment  at  the closing  of this  offering. In  return, the  Company granted
Bristol-Myers exclusive  worldwide  rights  to  antiangiogenic  applications  of
thalidomide, thalidomide analogs and Angiostatin-TM- protein.
    
 
    The  Company's  product  candidates have  been  developed  primarily through
sponsored  research  collaborations  and  licensing  agreements.  The  principal
antiangiogenesis  therapeutics currently  under development by  the Company were
licensed from Children's Hospital  at Harvard Medical  School where the  Company
sponsors  research  under  the  direction  of Dr.  M.  Judah  Folkman.  The flow
electroporation technology used in the cell permeation device was licensed  from
the  Center  for  Blood Research  Laboratories  at Harvard  Medical  School. The
Company's sponsored research programs are augmented by its internal capabilities
in the fields of the vasculature system, blood vessel growth and blood function.
 
                                       3
<PAGE>
    To date, the Company and its collaborators have:
 
    -Initiated Phase II clinical trials  to evaluate the antiangiogenic  effects
     of  thalidomide in  inhibiting the  progression of  breast cancer, prostate
     cancer and Kaposi's sarcoma.
 
    -Initiated Phase II clinical trials  to evaluate the antiangiogenic  effects
     of  thalidomide  in  inhibiting  the  progression  of  age-related  macular
     degeneration, a major cause of blindness.
 
    -Isolated,  identified,  sequenced,   cloned  and  recombinantly   expressed
     Angiostatin-TM-  protein. In  preclinical studies,  Angiostatin-TM- protein
     appeared to inhibit  vascularization and growth  of primary and  metastatic
     tumors.
 
    -Constructed a prototype device designed to introduce inositol hexaphosphate
     ("IHP")  molecules into red blood cells,  which may enhance the delivery of
     oxygen to organs and tissues in the body.
 
    The Company's strategy is to accelerate development of its  antiangiogenesis
and  cell permeation technologies as well  as other promising technologies which
the Company perceives to have  clinical and commercial potential. The  principal
elements  of the Company's  strategy are (i)  to focus its  resources on current
core technologies, (ii) to broaden its product and technology portfolio  through
sponsored   research  collaborations  with   academic  institutions,  government
organizations and private enterprises, (iii) to augment product development with
its in-house  research and  development capabilities  and (iv)  to leverage  its
resources  through corporate partnerships  in order to minimize  the cost to the
Company of  late-stage  clinical  trials and  to  accelerate  effective  product
commercialization.   All  of  the  Company's   product  candidates  are  in  the
development  stage  and  require  further  research,  development,  testing  and
regulatory clearances.
 
    The  Company was incorporated  in Delaware in  September 1991. The Company's
executive  offices  are  located  at  9610  Medical  Center  Drive,  Suite  200,
Rockville, Maryland 20850 and its telephone number is (301) 217-9858.
                                  THE OFFERING
 
   
<TABLE>
<S>                                            <C>
Common Stock offered hereby..................  3,200,000 shares
Common Stock to be outstanding after the
 offering....................................  11,993,912 shares (1)
Use of Proceeds..............................  For research and development, working capital
                                               and  general corporate purposes.  See "Use of
                                               Proceeds."
Proposed Nasdaq National Market symbol.......  ENMD
Risk Factors.................................  The Common  Stock offered  hereby involves  a
                                               high degree of risk. See "Risk Factors."
</TABLE>
    
 
- ------------------------
   
(1) Includes  (i) 333,333 shares  (assuming an initial  public offering price of
    $15.00 per share) to be sold to Bristol-Myers in a private placement on  the
    closing  of  this offering  at the  initial public  offering price  and (ii)
    2,000,000 shares of Common Stock  issuable upon the automatic conversion  of
    all  outstanding shares of Preferred Stock,  $1.00 par value (the "Preferred
    Stock") on the  date of this  Prospectus. Excludes (i)  2,381,688 shares  of
    Common Stock issuable upon exercise of outstanding options and warrants at a
    weighted  average exercise  price of $4.92  per share and  444,444 shares of
    Common Stock  issuable upon  exercise of  warrants issued  to  Bristol-Myers
    exercisable  at $22.50 per share (assuming  an initial public offering price
    of $15.00 per  share) and  (ii) an  additional 642,969  shares reserved  for
    issuance  under  the  Company's stock  option  plans.  See "Capitalization,"
    "Business -- Collaborations  and License Agreements,"  "Management --  Stock
    Options" and "Description of Capital Stock."
    
 
                                       4
<PAGE>
                             SUMMARY FINANCIAL DATA
 
   
<TABLE>
<CAPTION>
                                                                                                     THREE MONTHS ENDED MARCH
                                SEPTEMBER 18,                                                                  31,
                                1991 (DATE OF                 YEAR ENDED DECEMBER 31,                      (UNAUDITED)
                                INCEPTION) TO    --------------------------------------------------  ------------------------
                              DECEMBER 31, 1991     1992         1993         1994         1995         1995         1996
                              -----------------  -----------  -----------  -----------  -----------  -----------  -----------
<S>                           <C>                <C>          <C>          <C>          <C>          <C>          <C>
STATEMENT OF OPERATIONS DATA:
Revenues (1):
  Grant revenues............     $        --     $        --  $        --  $    90,185  $   347,001  $        --  $        --
  Collaborative research and
   development..............              --              --           --           --      347,501           --    1,042,500
  License fees..............              --              --           --           --       16,667           --       50,000
                              -----------------  -----------  -----------  -----------  -----------  -----------  -----------
Total revenues..............              --              --           --       90,185      711,169           --    1,092,500
Expenses:
  Research and development..              --         645,752    4,772,652    3,673,929    5,939,512    1,596,677    2,063,270
  General and
   administrative...........          23,873         812,198    1,552,143    1,549,705    2,458,976      455,342      771,411
  Interest expense..........              --              --           --           --       65,754           --        9,547
  Interest income...........              --         (56,383)     (85,939)     (18,993)     (44,854)      (5,559)     (76,321)
                              -----------------  -----------  -----------  -----------  -----------  -----------  -----------
Net loss....................     $   (23,873)    $(1,401,567) $(6,238,856) $(5,114,456) $(7,708,219) $(2,046,460) $(1,675,407)
                              -----------------  -----------  -----------  -----------  -----------  -----------  -----------
                              -----------------  -----------  -----------  -----------  -----------  -----------  -----------
Pro forma net loss per share
 (2)........................                                                            $     (0.83)              $     (0.18)
                                                                                        -----------               -----------
                                                                                        -----------               -----------
Pro forma weighted average
 number of shares
 outstanding (2)............                                                              9,271,943                 9,312,035
                                                                                        -----------               -----------
                                                                                        -----------               -----------
</TABLE>
    
 
   
<TABLE>
<CAPTION>
                                                                                          MARCH 31, 1996
                                                                                 --------------------------------
                                                                                     ACTUAL       AS ADJUSTED (3)
                                                                                 ---------------  ---------------
<S>                                                                              <C>              <C>
BALANCE SHEET DATA:
Cash and cash equivalents......................................................  $     7,600,058  $    56,000,058
Working capital................................................................        3,727,118       52,127,118
Total assets...................................................................        8,606,849       57,006,849
Deferred revenue, less current portion.........................................        2,566,667        2,566,667
Accumulated deficit............................................................      (22,162,378)     (22,162,378)
Total stockholders' equity.....................................................        2,051,853       50,451,853
</TABLE>
    
 
- ------------------------
(1) With   the  exception  of  license  fees  and  research  funding  under  the
    Bristol-Myers collaboration and research grants, the Company has not derived
    any revenues from operations. See  "Management's Discussion and Analysis  of
    Financial Condition and Results of Operations."
 
   
(2) Pro forma net loss per share and weighted average shares outstanding for the
    year ended December 31, 1995 and the three month period ended March 31, 1996
    give  effect to the automatic conversion  of 3,000,000 outstanding shares of
    Preferred Stock into 2,000,000 shares of Common Stock upon the date of  this
    Prospectus.
    
 
   
(3) Adjusted  to give effect to  the sale at an  assumed initial public offering
    price of $15.00  of (i)  the Common Stock  offered hereby  and (ii)  333,333
    shares  of  Common  Stock  by  the Company  to  Bristol-Myers  in  a private
    placement at the closing of this offering, and the receipt of the  estimated
    net proceeds therefrom.
    
 
                                       5
<PAGE>
                                  RISK FACTORS
 
   
    AN  INVESTMENT IN THE SHARES BEING OFFERED  HEREBY INVOLVES A HIGH DEGREE OF
RISK.  PROSPECTIVE  INVESTORS  SHOULD  CAREFULLY  CONSIDER  THE  FOLLOWING  RISK
FACTORS,  IN ADDITION TO THE OTHER  INFORMATION CONTAINED IN THIS PROSPECTUS, IN
EVALUATING  AN  INVESTMENT  IN  THE  SHARES  OF  COMMON  STOCK  OFFERED  HEREBY.
PROSPECTIVE  INVESTORS ARE CAUTIONED THAT THE STATEMENTS IN THIS PROSPECTUS THAT
ARE NOT DESCRIPTIONS OF HISTORICAL FACTS MAY BE FORWARD LOOKING STATEMENTS  THAT
ARE  SUBJECT TO RISKS AND UNCERTAINTIES.  ACTUAL RESULTS COULD DIFFER MATERIALLY
FROM THOSE CURRENTLY  ANTICIPATED DUE TO  A NUMBER OF  FACTORS, INCLUDING  THOSE
IDENTIFIED UNDER "RISK FACTORS" AND ELSEWHERE IN THIS PROSPECTUS.
    
 
   
    HISTORY  OF LOSSES; ACCUMULATED  DEFICIT AND ANTICIPATED  FUTURE LOSSES.  To
date, the  Company  has  been  engaged primarily  in  research  and  development
activities  and, with the exception of license fees and research and development
funding  under  the   collaboration  with   Bristol-Myers  (the   "Bristol-Myers
Collaboration")   and  research  grants,  has  not  derived  any  revenues  from
operations. At  March  31, 1996,  the  Company  had an  accumulated  deficit  of
approximately  $22,162,000 and significant  losses are expected  to continue for
the foreseeable  future. The  Company will  be required  to conduct  substantial
research and development and clinical testing activities for all of its proposed
products,  which activities are  expected to result in  operating losses for the
foreseeable future,  particularly due  to the  extended time  period before  the
Company  expects to  commercialize any  products, if  ever. In  addition, to the
extent the  Company relies  upon others  for development  and  commercialization
activities,  the Company's  ability to  achieve profitability  will be dependent
upon the success  of such  third parties.  There can  be no  assurance that  the
Company   will  be  able  to  generate   revenues  from  operations  or  achieve
profitability on a sustained basis, if at all. See "Management's Discussion  and
Analysis of Financial Condition and Results of Operations."
    
 
    EARLY  STAGE AND UNCERTAINTY OF PRODUCT DEVELOPMENT.  The Company's proposed
products and research programs are in the early developmental stage and  require
significant  time-consuming  and costly  research  and development,  testing and
regulatory clearances.  Accordingly, the  Company  does not  expect any  of  its
product  candidates to be commercially available for several years, if ever. The
successful development  of  any product  is  subject  to the  risks  of  failure
inherent  in  the development  of products  or  therapeutic procedures  based on
innovative technologies. These risks include  the possibilities that any or  all
of  these proposed products or procedures are  found to be ineffective or toxic,
or otherwise fail to receive necessary regulatory clearances; that the  proposed
products  or  procedures are  uneconomical to  manufacture or  market or  do not
achieve broad market acceptance; that third parties hold proprietary rights that
preclude the  Company  from marketing  them;  or  that third  parties  market  a
superior  or  equivalent  product. The  failure  of the  Company's  research and
development activities  to  result in  any  commercially viable  products  would
materially adversely affect the Company's future prospects.
 
   
    UNCERTAINTIES   RELATED  TO  CLINICAL  TRIALS.    The  Company  has  limited
experience in  conducting  clinical trials  and  intends to  rely  primarily  on
Bristol-Myers or other pharmaceutical companies with which it may collaborate in
the  future  for clinical  development and  regulatory  approval of  its product
candidates. Before obtaining regulatory approvals for the commercial sale of its
products, the  Company  or  its  collaborative  partners  will  be  required  to
demonstrate  through preclinical studies  and clinical trials  that the proposed
products are safe and effective for  use in each target indication. The  results
from  preclinical studies  and early  clinical trials  may not  be predictive of
results that  will be  obtained in  large-scale  testing, and  there can  be  no
assurance that the clinical trials conducted by the Company or its partners will
demonstrate  sufficient safety  and efficacy  to obtain  the required regulatory
approvals or will result in marketable products. One of the Company's  potential
products,  thalidomide,  is  believed to  have  caused severe  birth  defects in
children during the late  1950s and early 1960s.  Although the Company  believes
that the characteristics of thalidomide that may have affected fetal development
and  caused  birth  defects  by  blocking  new  blood  vessel  growth  may  make
    
 
                                       6
<PAGE>
   
thalidomide useful  in the  prevention and  treatment of  angiogenic  disorders,
there  can be no assurance  that clinical trials with  the drug will demonstrate
its safety and  efficacy or  that the  drug will  not be  associated with  other
characteristics that prevent or limit its commercial use.
    
 
   
    In  addition, clinical trials  are often conducted  with patients having the
most advanced stages of disease. During the course of treatment, these  patients
can  die or  suffer other adverse  medical effects  for reasons that  may not be
related to the  pharmaceutical agent  being tested, but  which can  nevertheless
affect  clinical trial results. Various companies in the pharmaceutical industry
have suffered  significant  setbacks in  advanced  clinical trials,  even  after
attaining  promising results in earlier trials.  Clinical trials for the product
candidates being developed by the Company  and its collaborators may be  delayed
by many factors. Any delays in, or termination of, the clinical trials of any of
the  Company's product candidates, or the failure of any clinical trials to meet
applicable regulatory standards,  could have  a material adverse  effect on  the
Company's business, financial condition and results of operations.
    
 
    DEPENDENCE   ON   BRISTOL-MYERS   AND  OTHER   COLLABORATIVE   PARTNERS  AND
LICENSEES.  The Company does not  intend to conduct late-stage clinical  trials,
or  manufacture  or market  any  of its  product  candidates in  the foreseeable
future. The Company has granted Bristol-Myers the right to conduct  development,
manufacturing, commercialization and marketing activities relating to certain of
the   Company's  antiangiogenesis  technologies.  Accordingly,  the  Company  is
substantially dependent  on  Bristol-Myers  for  the  development,  funding  and
commercial  success of  any of these  product candidates.  In addition, payments
from Bristol-Myers  may  constitute  a  substantial  portion  of  the  Company's
revenues  for the  next several  years. The  Bristol-Myers Collaboration  may be
terminated for any reason by Bristol-Myers on six months' notice, in which event
Bristol-Myers would have no  further funding obligation to  the Company. In  the
event  Bristol-Myers  were  to  terminate  its  agreement  with  the  Company or
otherwise fail to  conduct its  collaborative activities successfully  and in  a
timely  manner, the preclinical and clinical development or commercialization of
the licensed antiangiogenesis product candidates would be delayed or terminated.
Any such  delay or  termination could  have  a material  adverse effect  on  the
Company's  business, financial condition and  results of operations. The success
of the Bristol-Myers Collaboration will  depend in part upon Bristol-Myers'  own
competitive,  marketing  and  strategic considerations,  including  the relative
advantages of alternative products being developed and marketed by Bristol-Myers
and  its  competitors.  In  addition,   if  Bristol-Myers  is  unsuccessful   in
commercializing  any  product  candidates,  the  Company's  business,  financial
condition and  results of  operations would  be materially  adversely  affected.
Bristol-Myers  has agreed, as soon as reasonably practicable, to sublicense to a
third party ophthalmological applications of thalidomide and its analogs, unless
Bristol-Myers reasonably believes  that the dosage  or method of  administration
will not be significantly different from oncological indications. Any failure or
delay  by Bristol-Myers to enter into  such a sublicense may substantially limit
or preclude the commercial development of these applications.
 
    The Company intends to enter into additional corporate alliances to  develop
and  commercialize products  based upon its  cell permeation  technology and any
other technologies that may be acquired or developed by the Company. The Company
expects to  grant to  its  collaborative partners  rights to  commercialize  any
products  developed under  these collaborative  agreements, and  the Company may
rely on its collaborative partners  to conduct research and development  efforts
and  clinical trials  on, obtain regulatory  approvals for,  and manufacture and
market any  products  licensed to  these  partners.  The amount  and  timing  of
resources  devoted to these activities generally will be controlled by each such
individual partner.  Because the  Company  generally expects  to retain  only  a
royalty  interest in sales  or a percentage  of profits of  products licensed to
third  parties,   its  revenues   may  be   less  than   if  it   retained   all
commercialization  rights and marketed products directly. In addition, there can
be no  assurance  that  the  corporate  partners  will  not  pursue  alternative
technologies   or  develop  competitive  products  as  a  means  for  developing
treatments for the diseases targeted by the Company's programs.
 
                                       7
<PAGE>
    There  can  be  no  assurance  that  the  Company  will  be  successful   in
establishing  any additional  collaborative arrangements, that  products will be
successfully commercialized  under any  collaborative  arrangement or  that  the
Company  will  derive  any revenues  from  such arrangements.  In  addition, the
Company's  strategy  involves  entering  into  multiple,  concurrent   strategic
alliances  to pursue commercialization of its core technologies. There can be no
assurance that  the  Company  will  be  able  to  manage  simultaneous  programs
successfully.  With respect to existing and potential future strategic alliances
and collaborative arrangements, the Company will be dependent upon the expertise
and dedication  of sufficient  resources by  these outside  parties to  develop,
manufacture  or market  products. Should  a strategic  alliance or collaborative
partner fail to develop or commercialize a  product to which it has rights,  the
Company's  business,  financial condition  and  results of  operations  could be
materially and adversely affected.
 
   
    FUTURE  CAPITAL   NEEDS   AND   COMMITMENTS;   UNCERTAINTY   OF   ADDITIONAL
FUNDING.   The Company has incurred negative  cash flows since inception and has
expended, and expects to continue to  expend, substantial funds to continue  its
research  and development  programs. The  Company anticipates  that its existing
resources, together with the net proceeds of this offering and the proceeds from
the sale of  the BMS Shares  and committed funding  from Bristol-Myers, will  be
sufficient to fund the Company's operating expenses and capital requirements for
approximately  24 months from the date of this Prospectus, although there can be
no assurance that the  Company will not require  additional funds prior to  such
time.  There can be  no assurance that  the results of  research and development
activities, progress of preclinical  studies or clinical  trials, changes in  or
terminations  of relationships  with strategic  partners, changes  in the focus,
direction  or  costs  of  the  Company's  research  and  development   programs,
competitive and technological advances, the regulatory approval process or other
factors  will not  result in the  expenditure of the  Company's resources before
such time.  The  Company will  require  substantial  funds in  addition  to  the
proceeds  of  this  offering  to conduct  research  and  development activities,
preclinical studies  and clinical  trials, apply  for regulatory  approvals  and
commercialize any potential products, to the extent the Company engages directly
in such activities.
    
 
   
    The Company is a party to sponsored research agreements requiring it to fund
an  aggregate of approximately $6,492,000  through 1999 (including $6,000,000 to
Children's Hospital at Harvard Medical  School ("Children's Hospital")) and  has
recently  agreed to preliminary terms regarding  a proposed transaction that, if
consummated, would require the Company to fund additional sponsored research and
an equity investment in the approximate aggregate amount of $1,850,000 over  the
next two years. Pursuant to the terms of certain license agreements, the Company
is also obligated to exercise diligence in bringing potential products to market
and to make certain milestone payments that, in some instances, are substantial.
The  Company's  failure to  make any  required  sponsored research  or milestone
payment could result in  the termination of the  relevant sponsored research  or
license agreement, which could have a material adverse effect on the Company.
    
 
    The  Company may seek additional  funding through collaborative arrangements
and public or private financings, including  equity financings. There can be  no
assurance that such collaborative arrangements or that additional financing will
be  available on acceptable terms  or at all. If  additional funds are raised by
issuing equity  securities,  further dilution  to  stockholders may  result.  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   forfeit  its  rights  to  future  technologies;  to  obtain  funds  through
arrangements with collaborative partners or others that may require the  Company
to  relinquish  rights to  certain of  its  technologies, product  candidates or
products that  the Company  would  otherwise seek  to develop  or  commercialize
itself;  or  to  license the  rights  to such  products  on terms  that  are not
favorable to the Company. See "Use of Proceeds" and "Management's Discussion and
Analysis of  Financial Condition  and Results  of Operations"  and "Business  --
Collaborations and License Agreements."
 
                                       8
<PAGE>
    UNCERTAINTY   OF  GOVERNMENT   REGULATORY  REQUIREMENTS;   LENGTHY  APPROVAL
PROCESS.  The Company's research, development, preclinical and clinical  trials,
manufacturing  and marketing of most of its product candidates are subject to an
extensive regulatory  approval  process  by  the United  States  Food  and  Drug
Administration  (the "FDA") and  other regulatory agencies  in the United States
and abroad. The process of obtaining FDA and other required regulatory approvals
for drug  and biologic  products, including  required preclinical  and  clinical
testing,  is lengthy, expensive  and uncertain. There can  be no assurance that,
even after  such time  and expenditures,  the  Company will  be able  to  obtain
necessary  regulatory approvals for clinical testing or for the manufacturing or
marketing of  any  products. The  Company  or its  collaborators  may  encounter
significant  delays  or excessive  costs in  their  efforts to  secure necessary
approvals or  licenses. Even  if regulatory  clearance is  obtained, a  marketed
product  is  subject  to continual  review,  and later  discovery  of previously
unknown defects or failure to comply with the applicable regulatory requirements
may result in restrictions on a product's marketing or withdrawal of the product
from the market as well as  possible civil or criminal sanctions. See  "Business
- -- Government Regulation."
 
   
    COMPETITION;  RISK  OF  TECHNOLOGICAL  OBSOLESCENCE.    The  pharmaceutical,
biotechnology and bio-
    
pharmaceutical industries are intensely  competitive and competition from  other
companies  and other research and academic institutions is expected to increase.
Many of these companies have substantially greater financial and other resources
and  research  and   development  capabilities   than  the   Company  and   have
substantially greater experience in undertaking preclinical and clinical testing
of  products,  obtaining regulatory  approvals  and manufacturing  and marketing
pharmaceutical products. The Company is aware of other companies engaged in  the
development  of thalidomide  for various disease  indications, including Celgene
Corporation and Andrulis Pharmaceuticals,  and a number  of other companies  and
academic  institutions are pursuing angiogenesis  research and are testing other
angiogenesis  inhibitors.  The  Company's   blood  oxygen  enhancement   product
candidate  will  also  compete  for  certain  applications  with  numerous other
available  therapeutics  and  with  blood  and  blood  substitute  products   in
development  by others.  In addition  to competing  with universities  and other
research  institutions  in  the   development  of  products,  technologies   and
processes,  the Company may compete with  other companies in acquiring rights to
products or technologies from universities.
 
   
    Moreover, the pharmaceutical, biotechnology and biopharmaceutical industries
are rapidly evolving fields in which developments are expected to continue at  a
rapid  pace. There can  be no assurance  that the Company  will develop products
that are more effective  or achieve greater  market acceptance than  competitive
products,  or  that the  Company's competitors  will  not succeed  in developing
products and technologies that are more effective than those being developed  by
the  Company or that  would render the Company's  products and technologies less
competitive or obsolete. See "Business -- Competition."
    
 
    DEPENDENCE ON PATENTS  AND OTHER PROPRIETARY  RIGHTS; UNCERTAINTY OF  PATENT
POSITION  AND PROPRIETARY RIGHTS.  The Company's  success will depend in part on
its ability to  obtain patent protection  for its products,  both in the  United
States  and  abroad. The  patent  position of  biotechnology  and pharmaceutical
companies in general is highly uncertain and involves complex legal and  factual
questions.  Although  the  Company has  filed  a number  of  patent applications
related to  the  Company's  technologies  in  the  United  States,  and  foreign
counterparts  of certain of  these patent applications have  been filed in other
countries, no patents have been granted to date. There can be no assurance  that
any  patents will be granted  or that patents issued to  the Company will not be
challenged, invalidated or circumvented, or  that the rights granted  thereunder
will provide proprietary protection to the Company. Furthermore, there can be no
assurance  that others  will not independently  develop similar  products or, if
patents are issued to the Company  or its collaborators, will not design  around
such patents.
 
                                       9
<PAGE>
    Furthermore,  the  enactment  of the  legislation  implementing  the General
Agreement on Trade and Tariffs has resulted in certain changes to United  States
patent  laws that became  effective on June  8, 1995. Most  notably, the term of
patent protection for patent applications filed on  or after June 8, 1995 is  no
longer  a period of  seventeen years from the  date of grant. The  new term of a
United States patent will commence on the date of issuance and terminate  twenty
years  from the earliest  effective filing date of  the application. Because the
time from filing to issuance of  biotechnology patent application is often  more
than  three years,  a twenty-year  term from  the effective  date of  filing may
result in  a  substantially  shortened  term of  patent  protection,  which  may
adversely  impact the  Company's patent  position. If  this change  results in a
shorter period of  patent coverage,  the Company's business  could be  adversely
affected  to  the extent  that the  duration and  level of  the royalties  it is
entitled to receive from a collaborative partner is based on the existence of  a
valid patent.
 
    The  Company's potential products may conflict  with patents which have been
or may be granted to competitors,  universities or others. As the  biotechnology
industry  expands  and more  patents  are issued,  the  risk increases  that the
Company's potential products  may give  rise to  claims that  they infringe  the
patents  of others.  Such other  persons could  bring legal  actions against the
Company claiming damages and seeking  to enjoin clinical testing,  manufacturing
and  marketing of  the affected  products. Any  such litigation  could result in
substantial cost  to  the Company  and  diversion  of effort  by  the  Company's
management  and  technical personnel.  If any  such  actions are  successful, in
addition to any potential liability for  damages, the Company could be  required
to  obtain a license in order to  continue to manufacture or market the affected
products. There can be no assurance that  the Company would prevail in any  such
action  or  that  any license  required  under  any such  patent  would  be made
available on acceptable  terms, if  at all.  Failure to  obtain needed  patents,
licenses  or proprietary information held by  others may have a material adverse
effect on the Company's business. In  addition, if the Company becomes  involved
in  litigation, it could consume a substantial portion of the Company's time and
resources.
 
    Composition of matter  patent protection is  not available for  thalidomide.
The  Company is  aware of  at least  two other  issued patents  covering certain
non-antiangiogenic uses of thalidomide. Although  the Company believes that  the
claims  in such patents  will not interfere  with the Company's  proposed use of
thalidomide, there can be no assurance that the holders of such patents will not
be  able   to   exclude  the   Company   from  using   thalidomide   for   other
non-antiangiogenic uses of thalidomide.
 
    The  Company also relies on trade secret protection for its confidential and
proprietary information. However,  trade secrets  are difficult  to protect  and
there   can  be  no  assurance  that   others  will  not  independently  develop
substantially equivalent  proprietary information  and techniques  or  otherwise
gain  access to the Company's trade secrets or disclose such technology, or that
the Company can meaningfully protect its rights to unpatented trade secrets. The
Company  requires  its  employees,  consultants   and  advisors  to  execute   a
confidentiality  agreement upon the commencement  of an employment or consulting
relationship with the Company. The  agreements generally provide that all  trade
secrets  and  inventions  conceived  by  the  individual  and  all  confidential
information developed or  made known to  the individual during  the term of  the
relationship  shall be the exclusive  property of the Company  and shall be kept
confidential  and  not   disclosed  to   third  parties   except  in   specified
circumstances.  There can be  no assurance, however,  that these agreements will
provide meaningful protection for the  Company's proprietary information in  the
event of unauthorized use or disclosure of such information.
 
    To  the extent that consultants, key  employees or other third parties apply
technological information independently developed  by them or  by others to  the
Company's  proposed projects, disputes may arise as to the proprietary rights to
such information which may not be resolved  in favor of the Company. Certain  of
the  Company's consultants  are employed by  or have  consulting agreements with
third parties and any inventions  discovered by such individuals generally  will
not  become property  of the Company.  See "Business --  Patents and Proprietary
Rights."
 
                                       10
<PAGE>
   
    DEPENDENCE UPON KEY PERSONNEL AND CONSULTANTS.  The Company is dependent  on
certain  of its executive  officers and scientific  personnel, including John W.
Holaday, Ph.D., the Company's Chairman,  President and Chief Executive  Officer,
and  Carol Nacy, Ph.D., the Company's  Executive Vice President. The Company has
obtained and is  the beneficiary of  key person life  insurance policies in  the
face  amount of $1,000,000 on each of the lives of Drs. Holaday and Nacy and, in
April 1996  effective January  1,  1996, entered  into a  three-year  employment
agreement   with  Dr.   Holaday.  Competition  for   qualified  employees  among
pharmaceutical and biotechnology companies is  intense, and the loss of  certain
of  such persons,  or an  inability to  attract, retain  and motivate additional
highly skilled scientific, technical and management personnel, could  materially
adversely affect the Company's business and prospects. There can be no assurance
that  the Company will be  able to retain its  existing personnel or attract and
retain additional qualified employees.
    
 
    The Company may also be dependent, in part, upon the continued contributions
of the  lead investigators  of the  Company's sponsored  research programs.  The
Company's  scientific consultants and  collaborators may have  commitments to or
consulting or  advisory agreements  with other  entities that  may affect  their
ability  to contribute to  the Company or  may be competitive  with the Company.
Inventions or processes discovered by  such persons will not necessarily  become
the  property of the Company, but may remain  the property of such persons or of
such persons' full-time employers. See "Management."
 
    RISK OF  PRODUCT LIABILITY;  AVAILABILITY  OF INSURANCE.    The use  of  the
Company's  potential  products  in  clinical trials  and  the  marketing  of any
pharmaceutical products may expose the Company to product liability claims.  The
Company  has  obtained a  level of  liability insurance  coverage that  it deems
appropriate for  its current  stage of  development. However,  there can  be  no
assurance  that  the  Company's  present insurance  coverage  is  adequate. Such
existing coverage will not be adequate as the Company further develops products,
and no assurance can be given that in the future adequate insurance coverage  or
indemnification  by  collaborative  partners  will  be  available  in sufficient
amounts or at a reasonable cost. A successful product liability claim could have
a material  adverse  effect on  the  business  and financial  condition  of  the
Company.
 
    UNCERTAINTY  RELATED TO HEALTH CARE REIMBURSEMENT  AND REFORM MEASURES.  The
Company's success may depend, in part, on the extent to which reimbursement  for
the  costs of therapeutic products and related treatments will be available from
third-party payors such as government health administration authorities, private
health insurers, managed care  programs and other  organizations. Over the  past
decade,  the cost of  health care has  risen significantly, and  there have been
numerous proposals by legislators, regulators and third-party health care payors
to curb these costs.  Some of these proposals  have involved limitations on  the
amount  of reimbursement  for certain products.  There can be  no assurance that
similar federal or  state health  care legislation will  not be  adopted in  the
future  or that any products  sought to be commercialized  by the Company or its
collaborators will  be considered  cost-effective or  that adequate  third-party
insurance  coverage will be available for  the Company to establish and maintain
price levels  sufficient  for  realization  of  an  appropriate  return  on  its
investment  in product  development. Moreover, the  existence or  threat of cost
control measures could have an adverse  effect on the willingness or ability  of
Bristol-Myers   or  other   potential  collaborators  to   pursue  research  and
development programs related to the Company's product candidates.
 
    HAZARDOUS MATERIALS.   The Company's research  and development involves  the
controlled  use of hazardous, controlled  and radioactive materials. The Company
is subject to federal, state and  local laws and regulations governing the  use,
manufacture,  storage, handling and disposal of such materials and certain waste
products. Although the Company believes that its safety procedures for  handling
and  disposing of  such materials comply  with the standards  prescribed by such
laws and regulations, the risk of accidental contamination or injury from  these
materials cannot be completely eliminated.
 
                                       11
<PAGE>
In  the event  of such  an accident, the  Company could  be held  liable for any
damages that result and any such liability could have a material adverse  effect
on of the Company. See "Business -- Government Regulation."
 
    NO  MANUFACTURING OR  MARKETING CAPACITY.   The  Company does  not generally
expect to engage directly in manufacturing or marketing of products in the  near
term,  but may elect to  do so in certain cases.  The Company does not currently
have the capacity to  manufacture or market products  or any experience in  such
activities.  If the Company elects to  perform these functions, the Company will
be required  to either  develop these  capacities, or  contract with  others  to
perform  some  or  all  of  these  tasks. The  Company  may  be  dependent  to a
significant extent  on  corporate  partners, licensees  or  other  entities  for
manufacturing  and marketing  of products.  If the  Company engages  directly in
manufacturing or  marketing, the  Company  will require  substantial  additional
funds  and personnel and  will be required to  comply with extensive regulations
applicable to such a facility. There can  be no assurance that the Company  will
be  able to develop or contract for these capacities when required in connection
with the Company's business. See "Business -- Manufacturing and Marketing."
 
    ABSENCE OF PRIOR TRADING MARKET; POSSIBLE VOLATILITY OF STOCK PRICE.   Prior
to  this offering,  there has been  no public  market for the  Common Stock, and
there is no assurance that an active  market will develop or be sustained  after
this  offering.  The  initial  public  offering  price  will  be  determined  by
negotiation between the Company and the Representatives of the Underwriters  and
may bear no relationship to the price at which the Common Stock will trade after
completion  of this offering. See "Underwriting" for factors to be considered in
determining such offering price. The market price of the shares of Common Stock,
like that  of  the common  stock  of many  other  early-stage  biopharmaceutical
companies,  is likely  to be  highly volatile.  Factors such  as the  results of
preclinical studies and clinical trials by the Company or its competitors, other
evidence of the safety or efficacy of  product candidates of the Company or  its
competitors,  announcements  of  technological  innovations  or  new  commercial
therapeutic products by the Company or its competitors, governmental regulation,
changes in  reimbursement  policies,  healthcare  legislation,  developments  in
patent  or other proprietary rights, developments in the Company's relationships
with future collaborative partners, if any, public concern as to the safety  and
efficacy  of  drugs  developed by  the  Company, fluctuations  in  the Company's
operating results, and general market  conditions may have a significant  impact
on the market price of the Common Stock.
 
   
    FUTURE  SALES OF COMMON STOCK; REGISTRATION  RIGHTS.  Future sales of shares
of Common  Stock  by  existing  stockholders pursuant  to  Rule  144  under  the
Securities  Act of 1933, as amended (the "Securities Act"), through the exercise
of outstanding registration rights or through the sale of shares of Common Stock
issuable upon exercise of options, warrants or otherwise, could have an  adverse
effect  on the price of the Company's Common Stock. In addition to the 3,200,000
shares of Common Stock offered hereby, approximately 3,424,290 shares of  Common
Stock will be eligible for immediate resale in the public market and, subject to
compliance  with  Rule 144  under  the Securities  Act,  approximately 2,925,714
shares of Common Stock will be eligible for sale in the public market  beginning
90 days from the date of this Prospectus. An additional 855,930 shares of Common
Stock issuable upon the exercise of vested options and warrants will also become
eligible  for sale in the public market pursuant  to Rule 701 and Rule 144 under
the Securities  Act beginning  90 days  from the  date of  this Prospectus.  The
Securities  and Exchange  Commission has recently  proposed an  amendment to the
holding period  requirements  of  Rule  144  to  permit  resales  of  restricted
securities  after  a  one-year holding  period  rather than  a  two-year holding
period, and to permit  unrestricted resales by  non-affiliates after a  two-year
holding  period rather than a  three-year holding period. At  the request of the
Underwriters, the  Company  and  the  holders  of  approximately  96.5%  of  the
outstanding shares of Common Stock, including each stockholder holding in excess
of  1% of the outstanding shares and  each executive officer and director of the
Company, have agreed not to sell or transfer any of their shares for a period of
180 days from the date of this  Prospectus without the prior written consent  of
Allen & Company
    
 
                                       12
<PAGE>
   
Incorporated,  on behalf of  the Underwriters. Additionally,  beginning one year
from  the  date  of  this  Prospectus,  Bristol-Myers  is  entitled  to  certain
registration  rights with respect to 874,999 shares of Common Stock and warrants
to purchase 444,444 shares of Common Stock (which amounts include 333,333 shares
to be purchased upon the closing of  this offering and assume an initial  public
offering  price of $15.00 per  share) and, beginning 13  months from the date of
this Prospectus,  holders  of  1,157,344  shares of  Common  Stock  and  211,315
warrants  to purchase Common Stock will have registration rights with respect to
shares owned by them.  In addition, the  Company intends to file  a Form S-8  to
register  an aggregate  of 1,750,000  shares subject  to outstanding  options or
reserved for  issuance  pursuant  to  the  Company's  stock  option  plans.  See
"Description  of Capital Stock -- Registration  Rights" and "Shares Eligible for
Future Sale."
    
 
   
    DILUTION.  Investors purchasing shares of Common Stock in this offering will
incur  immediate  and   substantial  net   tangible  book   value  dilution   of
approximately  $10.80 per  share, or  72%, assuming  an initial  public offering
price of $15.00 per share.  This dilution will be  increased to the extent  that
holders  of outstanding options and warrants  to purchase Common Stock at prices
below  the  initial  public  offering   price  exercise  such  securities.   See
"Dilution."
    
 
   
    CONTROL OF COMPANY; POTENTIAL ANTI-TAKEOVER PROVISIONS.  Upon the completion
of this offering and the sale of the BMS Shares by the Company, the officers and
directors  of  the  Company  will  own  or  control  approximately  26%  of  the
outstanding shares of  Common Stock  of the  Company (25%  if the  Underwriters'
over-allotment  option is exercised in full). As a result, such individuals will
generally  be  able  to  influence   significantly  the  outcome  of   corporate
transactions or other matters submitted for stockholder approval. Such influence
by  principal  stockholders could  preclude any  unsolicited acquisition  of the
Company and consequently adversely affect the market price of the Common  Stock.
In  addition, the Company's Board of Directors  is authorized to issue from time
to time, without stockholder authorization, additional shares of preferred stock
with such terms and conditions  as the Board of  Directors may determine in  its
sole  discretion. The Company  is also subject to  a Delaware statute regulating
business combinations.  Any  of these  provisions  could discourage,  hinder  or
preclude an unsolicited acquisition of the Company and could make it less likely
that  stockholders receive a  premium for their  shares as a  result of any such
attempt. See "Management," "Principal Stockholders" and "Description of  Capital
Stock."
    
 
    OUTSTANDING  OPTIONS AND WARRANTS.  The  Company has outstanding options and
warrants to  purchase an  aggregate of  2,381,688 shares  of Common  Stock at  a
weighted  average  exercise price  of  $4.92 per  share  and warrants  issued to
Bristol-Myers  to  purchase  an  additional  444,444  shares  of  Common   Stock
exercisable  at $22.50 per  share (assuming an initial  public offering price of
$15.00 per share). Holders of such  options and warrants are likely to  exercise
them  when, in  all likelihood, the  Company could obtain  additional capital on
terms more  favorable  than those  provided  by  the options  and  warrants.  In
addition,  the exercise of such options and  warrants will result in dilution to
the interests of the stockholders of the Company to the extent that the exercise
price is less than the fair market value of the Common Stock. See "Management --
Stock Options" and "Description of Capital Stock."
 
   
    ABSENCE OF DIVIDENDS.  The Company has never paid any cash dividends on  its
Common  Stock  and does  not intend  to  pay cash  dividends in  the foreseeable
future. The Company currently  intends to retain all  earnings, if any, for  the
development of its business.
    
 
                                       13
<PAGE>
                                USE OF PROCEEDS
 
   
    The  net proceeds to  the Company from  the sale of  the 3,200,000 shares of
Common Stock offered  hereby, at  an assumed  initial public  offering price  of
$15.00  per share and  after deducting the  estimated underwriting discounts and
expenses payable by the Company,  are estimated to be approximately  $43,400,000
($50,060,000  if the Underwriters' over-allotment  option is exercised in full).
In addition, the net proceeds to the Company from the sale of the BMS Shares  by
the Company will be $5,000,000.
    
 
   
    The  Company currently intends  to use approximately  $34,000,000 of the net
proceeds of  this offering  and the  sale of  the BMS  Shares for  research  and
development  activities, of  which approximately  $16,000,000 is  expected to be
allocated to  its  antiangiogenesis  program, including  funding  sponsored  and
internal  early-stage  research,  approximately $11,000,000  is  expected  to be
allocated to its  cell permeation  technology, including the  evaluation of  the
technology  for a  variety of  disease indications  and therapeutic  agents, and
approximately $7,000,000  is expected  to  be allocated  to other  research  and
development  programs,  of  which  approximately $2,000,000  is  expected  to be
allocated to  sponsored research  on  cellular immunity  (in connection  with  a
proposed  acquisition) and approximately $5,000,000  is expected to be allocated
to sponsored research or acquisitions of new technologies, businesses or product
candidates. Although  the  Company  in  the  ordinary  course  of  its  business
investigates,  evaluates and discusses with  others such potential acquisitions,
except as described herein, the Company  has no agreements or arrangements  with
respect to such acquisitions. The remainder of the net proceeds of this offering
and  the sale of the BMS  Shares is expected to be  used for working capital and
general corporate purposes, a portion  of which may be  used to establish a  new
facility. However, the Company has not yet identified any potential new facility
for  lease or site  for building, and expects  to seek debt  financing to fund a
portion of such cost if it determines to build a facility.
    
 
   
    The  amounts,  timing   and  allocation  of   such  expenditures  may   vary
significantly  depending upon  numerous factors,  including the  progress of the
Company's  research  and  development  programs  (which  may  vary  as   product
candidates  are added  or abandoned),  preclinical testing  and clinical trials,
achievement  of  regulatory   milestones,  the   Company's  corporate   partners
fulfilling  their obligations  to the  Company, the  timing and  cost of seeking
regulatory approvals, the  level of resources  that the Company  devotes to  the
development   of  manufacturing,  marketing  and  sales  capabilities,  if  any,
technological advances, the status of competitors, the ability of the Company to
maintain existing  and  establish  new  collaborative  arrangements  with  other
companies  to provide  funding to  the Company  to support  these activities and
other factors.
    
 
   
    Pending such uses, the net proceeds from  this offering and the sale of  the
BMS  Shares will be temporarily invested  by the Company in short-term, interest
bearing, investment grade securities.
    
 
                                DIVIDEND POLICY
 
    The Company has never paid cash dividends on its capital stock and does  not
intend  to pay cash  dividends in the foreseeable  future. The Company currently
intends to retain all earnings, if any, for the development of its business.
 
                                       14
<PAGE>
                                 CAPITALIZATION
 
   
    The following  table  sets  forth  as  of March  31,  1996  (a)  the  actual
capitalization   of  the   Company  (after   giving  retroactive   effect  to  a
two-for-three reverse stock split of the  Common Stock effected in April  1996);
(b)  the pro  forma capitalization  of the  Company after  giving effect  to the
automatic conversion of  3,000,000 outstanding  shares of  Preferred Stock  into
2,000,000  shares of Common  Stock on the  date of this  Prospectus; and (c) the
capitalization as adjusted to reflect the  sale by the Company of the  3,200,000
shares  of Common  Stock offered  hereby and the  sale of  the BMS  Shares at an
assumed initial public offering price of $15.00 per share and the receipt of the
estimated net proceeds therefrom. This table should be read in conjunction  with
the  Financial  Statements  and the  Notes  thereto included  elsewhere  in this
Prospectus.
    
 
   
<TABLE>
<CAPTION>
                                                                    ACTUAL          PRO FORMA       AS ADJUSTED
                                                                ---------------  ---------------  ---------------
<S>                                                             <C>              <C>              <C>
Stockholders' Equity (1):
  Preferred Stock, $1.00 par value; 8,000,000 shares
   authorized; 3,000,000 shares issued and outstanding actual,
   no shares issued and outstanding pro forma and as
   adjusted...................................................        3,000,000               --               --
  Common Stock, $.01 par value; 27,000,000 shares authorized;
   6,460,579 shares issued and outstanding actual; 8,460,579
   shares issued and outstanding pro forma; and 11,993,912
   shares issued and outstanding as adjusted..................           64,606           84,606          119,939
  Additional paid-in capital..................................       21,149,625       24,129,625       72,494,292
  Accumulated deficit.........................................      (22,162,378)     (22,162,378)     (22,162,378)
                                                                ---------------  ---------------  ---------------
    Total stockholders' equity................................        2,051,853        2,051,853       50,451,853
                                                                ---------------  ---------------  ---------------
Total capitalization..........................................  $     2,051,853  $     2,051,853  $    50,451,853
                                                                ---------------  ---------------  ---------------
                                                                ---------------  ---------------  ---------------
</TABLE>
    
 
- ------------------------
 
   
(1) Does not include (i) 2,381,688 shares of Common Stock issuable upon exercise
    of outstanding options and warrants at a weighted average exercise price  of
    $4.92 per share and 444,444 shares of Common Stock issuable upon exercise of
     warrants  issued to Bristol-Myers exercisable at $22.50 per share (assuming
    an initial public offering price of $15.00 per share) and (ii) an additional
    642,969 shares reserved for issuance under the Company's stock option plans.
    See "Management -- Stock Options" and "Description of Capital Stock."
    
 
                                       15
<PAGE>
                                    DILUTION
 
   
    The pro forma  net tangible book  value of  the Company at  March 31,  1996,
after giving effect to the conversion of the Preferred Stock on the date of this
Prospectus,  was $2,005,755, or approximately $0.24 per share. Net tangible book
value per share is equal to the  Company's total tangible assets less its  total
liabilities,  divided by the number of shares of Common Stock outstanding. After
giving effect  to the  sale of  the 3,200,000  shares of  Common Stock  in  this
offering  and the sale of  the BMS Shares at  an assumed initial public offering
price of $15.00 per share and  receipt of the estimated net proceeds  therefrom,
the  pro  forma  net tangible  book  value at  March  31, 1996  would  have been
$50,405,755 or $4.20 per  share. This represents an  immediate increase in  such
net  tangible book  value of  $3.96 per  share to  existing stockholders  and an
immediate dilution  in  net tangible  book  value of  $10.80  per share  to  new
investors  purchasing shares in  this offering. The  following table illustrates
this per share dilution:
    
 
   
<TABLE>
<S>                                                                   <C>        <C>
Assumed initial public offering price per share.....................             $   15.00
  Pro forma net tangible book value per share at December 31,
   1995.............................................................  $    0.24
  Increase per share attributable to new investors..................       3.96
                                                                      ---------
Pro forma net tangible book value per share after this offering and
 the sale of the BMS Shares.........................................                  4.20
                                                                                 ---------
Dilution per share to new investors.................................             $   10.80
                                                                                 ---------
                                                                                 ---------
</TABLE>
    
 
   
    If the  Underwriters'  over-allotment option  were  exercised in  full,  the
adjusted  pro  forma  net  tangible  book  value  after  the  offering  would be
$57,105,755, resulting  in immediate  dilution to  new investors  of $10.42  per
share.
    
 
    The  following table summarizes on  a pro forma basis  at March 31, 1996 the
difference between  the number  of shares  of Common  Stock purchased  from  the
Company,  the total consideration paid  and the average price  per share paid by
existing stockholders  since inception  and by  new investors  in this  offering
(assuming  an  initial public  offering  price of  $15.00  per share  and before
deducting the estimated underwriting discounts and offering expenses):
 
   
<TABLE>
<CAPTION>
                                                                                TOTAL
                                              SHARES PURCHASED              CONSIDERATION           AVERAGE
                                         --------------------------  ---------------------------   PRICE PER
                                            NUMBER        PERCENT        AMOUNT        PERCENT       SHARE
                                         -------------  -----------  --------------  -----------  -----------
<S>                                      <C>            <C>          <C>             <C>          <C>
Existing Stockholders..................      8,460,579       70.5%   $   23,592,231       30.8%    $    2.79
New Investors (1)......................      3,533,333       29.5        53,000,000       69.2     $   15.00
                                         -------------      -----    --------------      -----
    Total..............................     11,993,912      100.0%   $   76,592,231      100.0%
                                         -------------      -----    --------------      -----
                                         -------------      -----    --------------      -----
</TABLE>
    
 
- ------------------------
 
   
(1) Includes the BMS Shares, which are being purchased from the Company upon the
    closing of this offering at the initial public offering price pursuant to  a
    private  placement.  Bristol-Myers also  is an  existing stockholder  of the
    Company. See "Principal Stockholders."
    
 
    The foregoing tables  do not give  effect to any  exercise of (i)  2,381,666
shares  of  Common  Stock  issuable upon  exercise  of  outstanding  options and
warrants at  a weighted  average exercise  price  of $4.92  per share  and  (ii)
444,444  shares of Common  Stock issuable upon  exercise of outstanding warrants
issued to  Bristol-Myers  of  Common  Stock  exercisable  at  $22.50  per  share
(assuming  an initial public offering price of  $15.00 per share). To the extent
that such options and warrants are exercised, there will be additional  dilution
to new investors. See "Management -- Stock Options."
 
                                       16
<PAGE>
                            SELECTED FINANCIAL DATA
 
   
    The  following selected financial data as  of December 31, 1991, 1992, 1993,
1994 and 1995 and for the period from September 18, 1991 (date of inception)  to
December 31, 1991 and the years ended December 31, 1992, 1993, 1994 and 1995 are
derived from the financial statements of EntreMed, Inc., which have been audited
by  Ernst  &  Young  LLP,  independent auditors.  The  data  should  be  read in
conjunction with the  financial statements,  related notes  and other  financial
information  included herein. The  selected financial data as  of March 31, 1996
and for the  three months ended  March 31, 1995  and 1996 are  derived from  the
unaudited financial statements of the Company which are also included herein. In
the opinion of management, the unaudited financial statements have been prepared
on  a basis  consistent with  the audited  financial statements  and include all
adjustments, consisting only of normal recurring accruals, necessary for a  fair
presentation  of  the financial  position and  results  of operations  for these
periods. The operating results for the three months ended March 31, 1996 are not
necessarily indicative of  results that may  be expected for  the entire  fiscal
year.
    
   
<TABLE>
<CAPTION>
                                                                                                                         THREE
                                                                                                                        MONTHS
                                                                                                                      ENDED MARCH
                                                 SEPTEMBER 18,                                                            31,
                                                 1991 (DATE OF                 YEAR ENDED DECEMBER 31,                (UNAUDITED)
                                                 INCEPTION) TO    --------------------------------------------------  -----------
                                               DECEMBER 31, 1991     1992         1993         1994         1995         1995
                                               -----------------  -----------  -----------  -----------  -----------  -----------
<S>                                            <C>                <C>          <C>          <C>          <C>          <C>
Statement of Operations Data:
Revenues (1):
  Grant revenues.............................     $        --     $        --  $        --  $    90,185  $   347,001  $        --
  Collaborative research and development.....              --              --           --           --      347,501           --
  License fees...............................              --              --           --           --       16,667           --
                                               -----------------  -----------  -----------  -----------  -----------  -----------
    Total revenues...........................              --              --           --       90,185      711,169           --
 
Expenses:
  Research and development...................              --         645,752    4,772,652    3,673,929    5,939,512    1,596,677
  General and administrative.................          23,873         812,198    1,552,143    1,549,705    2,458,976      455,342
  Interest expense...........................              --              --           --           --       65,754           --
  Interest income............................              --         (56,383)     (85,939)     (18,993)     (44,854)      (5,559)
                                               -----------------  -----------  -----------  -----------  -----------  -----------
Net loss.....................................     $   (23,873)    $(1,401,567) $(6,238,856) $(5,114,456) $(7,708,219) $(2,046,460)
                                               -----------------  -----------  -----------  -----------  -----------  -----------
                                               -----------------  -----------  -----------  -----------  -----------  -----------
Pro forma net loss per share (2).............                                                            $     (0.83)
                                                                                                         -----------
                                                                                                         -----------
Pro forma weighted average number of shares
 outstanding (2).............................                                                              9,271,943
                                                                                                         -----------
                                                                                                         -----------
 
<CAPTION>
 
                                                  1996
                                               -----------
<S>                                            <C>
Statement of Operations Data:
Revenues (1):
  Grant revenues.............................  $        --
  Collaborative research and development.....    1,042,500
  License fees...............................       50,000
                                               -----------
    Total revenues...........................    1,092,500
Expenses:
  Research and development...................    2,063,270
  General and administrative.................      771,411
  Interest expense...........................        9,547
  Interest income............................      (76,321)
                                               -----------
Net loss.....................................  $(1,675,407)
                                               -----------
                                               -----------
Pro forma net loss per share (2).............  $     (0.18)
                                               -----------
                                               -----------
Pro forma weighted average number of shares
 outstanding (2).............................    9,312,035
                                               -----------
                                               -----------
</TABLE>
    
   
<TABLE>
<CAPTION>
                                                                                 DECEMBER 31,
                                                        ---------------------------------------------------------------
                                                          1991        1992         1993          1994          1995
                                                        ---------  -----------  -----------  ------------  ------------
<S>                                                     <C>        <C>          <C>          <C>           <C>
BALANCE SHEET DATA:
Cash and cash equivalents.............................  $   2,342  $ 1,399,072  $ 2,188,665  $    218,619  $  6,885,099
Working capital (deficit).............................    (18,671)   1,356,666    2,112,738      (332,427)    5,689,810
Total assets..........................................     23,640    1,586,691    3,258,995       843,742    10,146,383
Deferred revenue, less current portion................         --           --           --            --     2,741,666
Long-term debt........................................         --           --           --            --       104,152
Accumulated deficit...................................    (23,873)  (1,401,567)  (7,280,210)  (12,778,752)  (20,486,971)
Total stockholders' equity (deficit)..................     (2,627)   1,524,235    3,183,068       292,696     3,601,260
 
<CAPTION>
 
                                                        MARCH 31, 1996
                                                        --------------
<S>                                                     <C>
BALANCE SHEET DATA:
Cash and cash equivalents.............................   $  7,600,058
Working capital (deficit).............................      3,727,118
Total assets..........................................      8,606,849
Deferred revenue, less current portion................      2,566,667
Long-term debt........................................             --
Accumulated deficit...................................    (22,162,378)
Total stockholders' equity (deficit)..................      2,051,853
</TABLE>
    
 
- ------------------------
(1) With   the  exception  of  license  fees  and  research  funding  under  the
    Bristol-Myers Collaboration and research grants, the Company has not derived
    any revenues from operations. See  "Management's Discussion and Analysis  of
    Financial Condition and Results of Operations."
 
   
(2) Pro forma net loss per share and weighted average shares outstanding for the
    year ended December 31, 1995 and the three month period ended March 31, 1996
    give  effect to the automatic conversion  of 3,000,000 outstanding shares of
    Preferred Stock into 2,000,000  shares of Common Stock  on the date of  this
    Prospectus.
    
 
                                       17
<PAGE>
                    MANAGEMENT'S DISCUSSION AND ANALYSIS OF
                 FINANCIAL CONDITION AND RESULTS OF OPERATIONS
 
OVERVIEW
 
    Since its inception in September 1991, the Company has devoted substantially
all  of  its efforts  and resources  to sponsoring  and conducting  research and
development on its own behalf and through collaborations with corporate partners
and academic research and clinical institutions, and establishing its facilities
and hiring personnel. Prior to 1994, the primary focus of the Company's research
and development efforts and  expenditures was the  development of vaccines.  The
Company  has  substantially reduced  its  vaccine related  development activity,
reflecting in part its desire to prioritize its limited financial resources  and
the   perceived   greater   proprietary   and   commercial   potential   of  its
antiangiogenesis and blood cell permeation technology programs.
 
   
    With the exception of license fees and research and development funding from
Bristol-Myers and certain  research grants,  the Company has  not generated  any
revenue  from operations. For the  period from inception to  March 31, 1996, the
Company incurred a cumulative net loss of approximately $22,162,000 and  expects
to  incur additional  operating losses for  the foreseeable  future. In December
1995, the  Company entered  into the  Bristol-Myers Collaboration  and,  through
March  31, 1996, had received $5,700,000 in license and research and development
fees and expense reimbursements and  a $6,500,000 equity investment pursuant  to
this  alliance. The Company  expects that its  revenue sources for  at least the
next several years will be limited  to research grants and future  collaboration
payments from Bristol-Myers and from other collaborators under arrangements that
may  be entered into in the future. The  timing and amounts of such revenues, if
any, will likely fluctuate sharply and depend upon the achievement of  specified
milestones,  and results of  operations for any  period may be  unrelated to the
results of operations for any other period. See "Business -- Collaborations  and
License Agreements."
    
 
RESULTS OF OPERATIONS
 
   
    THREE MONTHS ENDED MARCH 31, 1995 AND 1996
    
 
   
    Revenues  under  collaborative  research  and  development  agreements  were
$1,092,500 for the three months ended March 31, 1996 as compared to no  revenues
for  the  three months  ended  March 31,  1995.  The collaborative  research and
development fees  relate to  the  amortization over  five  years of  a  one-time
payment  of  $2,500,000  and the  amortization  over six  months  of semi-annual
payments of $1,835,000 under the  Bristol-Myers Collaboration. The license  fees
represent  the amortization over five years of a one-time $1,000,000 license fee
under the Bristol-Myers Collaboration, a portion of which was paid to Children's
Hospital. Three month's amortization of these  amounts is included in the  three
month  period  ended  March 31,  1996,  as the  Bristol-Myers  Collaboration was
entered into in December 1995.
    
 
   
    Research and  development  expenses  increased  by  29%  from  approximately
$1,597,000  in the three months ended March 31, 1995 to approximately $2,063,000
in the three months ended March 31, 1996. Research and development  expenditures
related  to sponsored research payments increased by 53% from $1,052,000 for the
three months ended March 31, 1995  to $1,605,000 in the corresponding period  in
1996,  reflecting  increased efforts  in  the Company's  sponsored  research and
product development programs  related to  its angiogenesis  and cell  permeation
technologies.
    
 
   
    General  and administrative  expenses increased by  69% in  the three months
ended March 31, 1996  to approximately $771,000  from approximately $455,000  in
the  three  months  ended  March 31,  1995,  reflecting  the  Company's expanded
operations and a  one-time charge  of $233,000  related to  the future  payments
under  a termination agreement with Steve  Gorlin, a founder and former director
of the Company. Mr. Gorlin ceased  providing services to the Company during  the
three  months ended March 31, 1996. See "Certain Transactions." Interest expense
increased from zero in the three
    
 
                                       18
<PAGE>
   
months ended March 31, 1995 to $10,000 in the three months ended March 31,  1996
as a result of the completion, subsequent to March 31, 1995, of a sale-leaseback
agreement.  Interest income increased to $76,000 in the three months ended March
31, 1996 from $6,000  in the corresponding  period in 1995, as  a result of  the
additional   capital  available  to  invest   following  the  execution  of  the
Bristol-Myers Collaboration.
    
 
    YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
   
    Revenues  under  collaborative  research  and  development  agreements  were
approximately  $348,000 and license fees were  approximately $17,000 in the year
ended December 31, 1995. The collaborative research and development fees  relate
to  the amortization over five years of a one-time payment of $2,500,000 and the
amortization over six months of a  semi-annual payments of $1,835,000 under  the
Bristol-Myers  Collaboration. The  license fees represent  the amortization over
five years  of  a  one-time  $1,000,000  license  fee  under  the  Bristol-Myers
Collaboration, a portion of which was paid to Children's Hospital. Approximately
one   month's  amortization  of  these  amounts  is  included  in  1995  as  the
Bristol-Myers Collaboration was entered into  in December 1995. The Company  had
no collaboration revenues in 1993 or 1994. In addition, revenues during 1994 and
1995  included grant revenues from World  Health Organization and SBIR grants of
$90,000 and $347,000, respectively.
    
 
    Research and  development  expenses  decreased  by  23%  from  approximately
$4,773,000  in 1993 to $3,674,000 in  1994, reflecting the reduction in expenses
relating to  the  Company's  decreased  emphasis  on  vaccine  development,  and
increased by 62% to approximately $5,940,000 in 1995, due primarily to increased
efforts in the Company's internal and sponsored research and product development
programs related to its antiangiogenesis and blood cell permeation technologies.
Research  and development  expenditures included sponsored  research payments of
approximately $3,054,000, $1,369,000  and $2,570,000 and  internal research  and
development  expenses of approximately $1,719,000,  $2,305,000 and $3,370,000 in
1993, 1994 and 1995, respectively.
 
    General and administrative expenses remained relatively constant in 1993 and
1994 and increased by  59% in 1995  to $2,459,000 from $1,550,000  in 1994 as  a
result  of  increases  in  the  number  of  Company  personnel.  Interest income
decreased from $86,000 in 1993  to $19,000 in 1994  and increased to $45,000  in
1995,  reflecting the  lower average cash  balance during  1994, which increased
during 1995.  During 1995,  the Company  had interest  expense of  approximately
$66,000 as a result of capital lease obligations.
 
LIQUIDITY AND CAPITAL RESOURCES
 
   
    From  inception through March 31, 1996,  the Company financed its operations
from (i)  the net  proceeds of  private placements  of equity  securities  which
raised  approximately $17,000,000,  (ii) payments  from Bristol-Myers, including
$9,700,000 received  in  December  1995  (of  which  $6,500,000  was  an  equity
investment) and $2,500,000 received in March 1996, (iii) various grants from the
World Health Organization and Small Business Innovation Research ("SBIR") grants
totalling  approximately $437,000  and (iv)  proceeds of  approximately $654,000
under capital leases.
    
 
    Bristol-Myers is obligated  to make additional  semi-annual payments to  the
Company  of  $1,835,000 in  each  of June  and  December through  June  2000 and
$365,000 in December 1996  as well as additional  payments in the event  certain
mostly   late-stage  regulatory  milestones   are  achieved.  Bristol-Myers  may
terminate the collaboration agreement and return the licensed technology to  the
Company  at any time  upon six months' notice,  in which event  it would have no
further funding obligation to the  Company. See "Business -- Collaborations  and
License Agreements."
 
   
    At  March  31,  1996,  the  Company  had  working  capital  of approximately
$3,727,000. The Company's cash resources have been used to finance research  and
development,  including  sponsored  research,  capital  expenditures,  including
leasehold improvements to  the Company's  laboratory facility,  and general  and
administrative  expenses. Over  the next several  years, the  Company expects to
    
 
                                       19
<PAGE>
incur substantial  additional research  and development  costs, including  costs
related  to  early-stage  research  in areas  not  reimbursed  by Bristol-Myers,
preclinical and clinical  trials, increased administrative  expenses to  support
its  research and development operations  and increased capital expenditures for
pilot manufacturing capacity, various equipment needs and facility improvements.
 
   
    At March 31, 1996, the Company was a party to sponsored research  agreements
requiring  it  to fund  an aggregate  of  approximately $6,492,000  through 1999
(including $6,000,000 to Children's  Hospital) and license agreements  requiring
milestone  payments of up to $2,360,000  and additional payments upon attainment
of regulatory  milestones.  In addition,  the  Company has  recently  agreed  to
preliminary  terms regarding a proposed  transaction that, if consummated, would
require the  Company  to  fund  additional  sponsored  research  and  an  equity
investment  in the approximate aggregate amount  of $1,850,000 over the next two
years. The Company  is also a  party to an  office lease expiring  in 2003  with
total  future  minimum lease  payments of  $1,620,300.  See Note  4 of  Notes to
Financial Statements. See "Business -- Collaborations and License Agreements."
    
 
   
    At  December  31,  1995,  the  Company  had  available  net  operating  loss
carryforwards of $17,100,000 to offset any future taxable income for federal tax
purposes.  The utilization  of the  loss carryforwards  to reduce  future income
taxes will depend on the Company's ability to generate sufficient taxable income
prior  to  the  expiration  of   the  net  operating  loss  carryforwards.   The
carryforwards  begin to expire in the year  2006. However, the Tax Reform Act of
1986 limits  the  maximum  annual use  of  net  operating loss  and  tax  credit
carryforwards  in certain situations where changes  occur in the stock ownership
of a corporation. For  financial reporting purposes,  a valuation allowance  has
been  recognized  to  reduce  the  net  deferred  tax  assets  to  zero  due  to
uncertainties with respect to the  Company's ability to generate taxable  income
in  the future sufficient to realize the  benefit of deferred income tax assets.
See Note 8 of Notes to Financial Statements.
    
 
   
    The Company believes that the net  proceeds from this offering and from  the
sale  of the BMS Shares by the Company, together with its existing resources and
committed funding from  Bristol-Myers, will  be sufficient to  meet its  capital
needs  for  approximately 24  months,  although there  can  be no  assurance the
Company will  not require  additional funds  prior to  such date.  However,  the
Company's  working  capital  requirements  will  depend  upon  numerous factors,
including the progress of the Company's research and development programs (which
may vary as product candidates are added or abandoned), preclinical testing  and
clinical  trials, achievement of regulatory  milestones, the Company's corporate
partners fulfilling their  obligations to the  Company, the timing  and cost  of
seeking regulatory approvals, the level of resources that the Company devotes to
the  development  of manufacturing,  marketing and  sales capabilities,  if any,
technological advances, the status of competitors, the ability of the Company to
maintain existing  and  establish  new  collaborative  arrangements  with  other
companies  to provide  funding to  the Company  to support  these activities and
other factors.  In any  event, the  Company will  require substantial  funds  in
addition  to  the  proceeds of  this  offering  to develop  any  of  its product
candidates and otherwise  to meet its  business objectives. The  Company has  no
commitments  to obtain any additional  funds and there can  be no assurance such
funds will be available on acceptable terms, or at all.
    
 
                                       20
<PAGE>
                                    BUSINESS
 
GENERAL
 
    EntreMed  is  engaged   primarily  in  the   research  and  development   of
biopharmaceutical  products that address the role  of blood and blood vessels in
the prevention and treatment  of a broad range  of diseases. The Company's  core
technologies  include (i) an antiangiogenesis program focused on the development
of proprietary products  intended to inhibit  the abnormal growth  of new  blood
vessels  associated with cancer and certain causes of blindness and (ii) a blood
cell permeation device  designed to enhance  the ability of  red blood cells  to
deliver  oxygen to  organs and  tissues and  which may  also be  used to deliver
drugs, genes  or  other therapeutic  agents  that otherwise  would  not  readily
diffuse through blood cell membranes.
 
    Angiogenesis  is  the fundamental  process by  which  new blood  vessels are
formed  and  primarily  occurs  during  the  first  three  months  of  embryonic
development.  Except  for wound  healing and  certain reproductive  processes in
women, angiogenesis  is otherwise  generally associated  with several  diseases,
including  cancer and  certain causes  of blindness.  The Company  believes that
antiangiogenic products, which inhibit the abnormal growth of blood vessels, may
have significant advantages over traditional  therapies for these diseases.  The
Company  is  currently  developing  several  angiogenesis  inhibitors, including
thalidomide and its chemical analogs and Angiostatin-TM-, a protein produced  by
the  body.  The Company  is also  applying its  expertise in  the role  of blood
function to  the development  of  a blood  cell  permeation device  designed  to
enhance the oxygen releasing capabilities of red blood cells. Organs and tissues
in  the body require oxygen to function  properly and oxygen deficiency may lead
to tissue damage or death.
 
   
    In  December   1995,   the   Company  and   Bristol-Myers   Squibb   Company
("Bristol-Myers")    entered   into   a    collaboration   (the   "Bristol-Myers
Collaboration")  to   develop   and   commercialize   certain   antiangiogenesis
therapeutics.  This  collaboration provides  for  Bristol-Myers to  fund Company
research, provide  milestone  payments  to  the  Company  and  pay  the  Company
royalties  on net  sales of any  products developed under  the collaboration. In
addition, Bristol-Myers made a $6,500,000  equity investment in the Company  and
agreed  to make an  additional $5,000,000 equity investment  upon the closing of
this offering. In return, the Company granted Bristol-Myers exclusive  worldwide
rights  to antiangiogenic  applications of thalidomide,  thalidomide analogs and
Angiostatin-TM- protein.
    
 
    The Company's  product  candidates  have been  developed  primarily  through
sponsored  research  collaborations  and  licensing  agreements.  The  principal
antiangiogenesis therapeutics currently  under development by  the Company  were
licensed  from  Children's  Hospital  at  Harvard  Medical  School  ("Children's
Hospital") where the  Company sponsors research  under the direction  of Dr.  M.
Judah  Folkman. The flow electroporation technology  used in the cell permeation
device was licensed from the Center  for Blood Research Laboratories at  Harvard
Medical School ("CBRL"). The Company's sponsored research programs are augmented
by  its internal  capabilities in  the fields  of the  vasculature system, blood
vessel growth and blood function.
 
    To date, the Company and its collaborators have:
 
    -Initiated Phase II clinical trials  to evaluate the antiangiogenic  effects
     of  thalidomide in  inhibiting the  progression of  breast cancer, prostate
     cancer and Kaposi's sarcoma.
 
    -Initiated Phase II clinical trials  to evaluate the antiangiogenic  effects
     of  thalidomide  in  inhibiting  the  progression  of  age-related  macular
     degeneration, a major cause of blindness.
 
    -Isolated,  identified,  sequenced,   cloned  and  recombinantly   expressed
     Angiostatin-TM-  protein. In  preclinical studies,  Angiostatin-TM- protein
     appeared to inhibit  vascularization and growth  of primary and  metastatic
     tumors.
 
    -Constructed a prototype device designed to introduce inositol hexaphosphate
     ("IHP")  molecules into red blood cells,  which may enhance the delivery of
     oxygen to organs and tissues in the body.
 
                                       21
<PAGE>
CORPORATE STRATEGY
 
    The Company's strategy is to accelerate development of its  antiangiogenesis
and  cell permeation technologies as well  as other promising technologies which
the Company perceives to have  clinical and commercial potential. The  principal
elements  of the Company's  strategy are (i)  to focus its  resources on current
core technologies, (ii) to broaden its product and technology portfolio  through
sponsored   research  collaborations  with   academic  institutions,  government
organizations and private enterprises, (iii) to augment product development with
its in-house research and development capabilities
and (iv) to leverage  its resources through corporate  partnerships in order  to
minimize the cost to the Company of late-stage clinical trials and to accelerate
effective product commercialization.
 
ANGIOGENESIS
 
    OVERVIEW
 
    Within  the human body, a network  of arteries, capillaries and veins, known
as the vasculature, functions to transport blood throughout the body. The  basic
network  of  the vasculature  is developed  through angiogenesis,  a fundamental
process by which new blood vessels are formed. The primary angiogenic period  in
humans  takes  place during  the first  three  months of  embryonic development.
During this period, cytokines and growth factors, which are normally suppressed,
are activated to  stimulate the growth  of new blood  vessels. Once the  general
network  of  the blood  vessels is  complete,  these angiogenic  stimulators are
inhibited and blood vessels grow longer  and larger in diameter until  adulthood
through  a different process termed vasculogenesis. Although angiogenesis occurs
in embryonic development, wound healing and in certain reproductive processes in
women, angiogenesis  is otherwise  generally associated  with several  diseases,
including  cancer  and diabetic  retinopathy and  macular degeneration,  both of
which are major causes of blindness.
 
    ANGIOGENESIS AND CANCER
 
    The term  cancer  includes many  different  types of  uncontrolled  cellular
growth. Clusters of cancer cells, referred to as tumors, may destroy surrounding
organs,  impair  physiological function  and often  lead to  death. In  order to
survive, cancer cells require oxygen and  nutrients which they receive from  the
body's blood supply. In order to access this blood supply, cancer cells initiate
a  biochemical mechanism that stimulates  angiogenesis, which provides the blood
supply that nourishes the  tumor. As cancer cells  grow and metastasize  (spread
from  primary sites  to secondary  sites) they  require continuous angiogenesis.
Antiangiogenic substances are intended  to inhibit the  growth of blood  vessels
and  may  be effective  in  treating certain  cancers,  with fewer  adverse side
effects than traditional therapies. Cancer is the second leading cause of  death
in  the United States and it is estimated that approximately 1,360,000 new cases
of cancer will be diagnosed in 1996.
 
    Existing  cancer   treatments  include   surgery,  radiation   therapy   and
chemotherapy.  Surgery requires  invasive procedures to  remove cancerous cells.
Often, cancer tumors  located in sites  that are difficult  to access or  tumors
that  have metastasized to vital organs  cannot be treated surgically. Radiation
therapy produces ionized molecules within the body that attack cancer cells  but
which may also damage healthy cells. Chemotherapy involves the administration of
toxic  substances designed to kill cancer cells and usually produces severe side
effects. In addition, resistance to  chemotherapy occurs over time. The  Company
believes  that its antiangiogenesis technologies may have significant advantages
over traditional  cancer  therapies,  including reduced  toxicity,  and  may  be
administered in conjunction with such other therapies.
 
    ANGIOGENESIS AND BLINDNESS
 
    Angiogenesis  within the eye, a condition often associated with diabetes and
age-related macular  degeneration,  is  a  major  cause  of  blindness.  Macular
degeneration, which is age-related, and diabetic retinopathy, a secondary effect
of  diabetes, both  involve the formation  of new  blood vessels in  front of or
behind the retina. The blood  vessels that grow in  front of the retina  occlude
vision  and the blood  vessels that grow  behind the retina  often hemorrhage or
cause the detachment of the retina, in  each case resulting in blindness. It  is
estimated    that   approximately    8,000,000   people    experience   diabetic
 
                                       22
<PAGE>
retinopathy, and that  25,000 new cases  of blindness develop  each year. It  is
estimated that approximately 13,000,000 people suffer from macular degeneration,
and  that 1,700,000  develop vision  impairment, of  which 100,000  new cases of
blindness develop each year. Current treatments for diabetic retinopathy and, to
a more limited extent, macular degeneration involve laser-based photocoagulation
treatments, which often cause  unintended damage to  the retina and  surrounding
cells.
 
    ANGIOGENESIS AND OTHER DISEASE INDICATIONS
 
    A  variety of other disease indications may be associated with angiogenesis,
including  rheumatoid  arthritis,   cardiovascular  disease   (atherosclerosis),
psoriasis  and Crohn's disease.  The Company believes  that its antiangiogenesis
technologies may be applicable to these other diseases. To date, the Company has
not pursued research for applications of antiangiogenesis to diseases outside of
cancer or macular degeneration. There can be no assurance that the Company  will
pursue  research outside these indications,  that product candidates will result
from any research undertaken or that  any products for these diseases will  ever
be commercialized.
 
ENTREMED'S ANTIANGIOGENESIS PROGRAM
 
    The   Company  believes  that   certain  drugs  or   proteins  that  exhibit
antiangiogenic effects may be used as effective, safe therapeutics for  diseases
involving angiogenesis. The Company currently focuses on angiogenesis inhibition
as  a  treatment  for  cancer, macular  degeneration  and  diabetic retinopathy.
Product candidates under development include: (i) thalidomide and several of its
chemical  analogs   which  focus   the  therapeutic   activity  of   thalidomide
specifically   on  angiogenesis  and  (ii)   Angiostatin-TM-  protein,  a  newly
discovered angiogenesis inhibitor naturally produced by the body. The  Company's
evaluation   of  thalidomide   and  its   chemical  analogs   as  antiangiogenic
therapeutics will also  enable the  Company to generate  clinical and  marketing
data  on the general utility of angiogenesis  inhibitors. These data can then be
applied in  the  development  of  Angiostatin-TM-  protein,  which  the  Company
believes may have greater efficacy as an antiangiogenic therapeutic. The Company
believes  that, if successfully developed, these products could be used alone or
in combination with each other to treat certain angiogenic diseases.
 
    PRODUCT CANDIDATES
 
    ORAL ANTIANGIOGENESIS DRUG.   The Company  is evaluating the  antiangiogenic
properties  of the drug thalidomide and its chemical analogs. Thalidomide, which
was widely prescribed as a sedative in Europe in the late 1950s and early 1960s,
is believed  to  have caused  severe  birth  defects in  children.  The  Company
believes  that thalidomide may have affected  fetal development and caused birth
defects by blocking  new blood  vessel growth,  a characteristic  that may  make
thalidomide  useful in the prevention and  treatment of angiogenic disorders. In
preclinical animal  studies conducted  at Children's  Hospital, thalidomide  has
been  shown to block angiogenesis. Because  of the negative precedent associated
with thalidomide, as  well as patent  and competitive issues,  the Company  also
intends  to screen for  and conduct research on  chemical analogs of thalidomide
having substantially similar mechanisms of  action as thalidomide but which  may
focus  the therapeutic activity  of this drug  specifically on angiogenesis. The
Company proposes to develop thalidomide or  a thalidomide analog as a  long-term
patient  administered  oral therapeutic  to inhibit  the progression  of certain
angiogenic diseases, including cancer and certain causes of blindness.
 
    The Company,  Bristol-Myers  and  the  National  Cancer  Institute  recently
initiated  Phase II  clinical trials to  evaluate the  antiangiogenic effects of
thalidomide in inhibiting the progression of breast cancer, prostate cancer  and
Kaposi's  sarcoma. The Company  and its collaborators  intend to conduct similar
studies regarding brain  cancer in the  near future. Based  on results of  these
studies,  as well as development activities relating to thalidomide analogs, the
Company will  determine,  together with  Bristol-Myers,  whether to  pursue  the
commercialization  of thalidomide by  expanding these trials  or by initiating a
Phase III trial,  or to develop  an analog  of thalidomide, or  both. In  animal
studies  performed at Children's Hospital, thalidomide  was shown to inhibit the
abnormal formation of blood vessels in the eye, a major cause of blindness.  The
Company is currently conducting Phase II clinical
 
                                       23
<PAGE>
trials  at the Scheie Eye Institute at  the University of Pennsylvania School of
Medicine  and  with  the  Retina   Associates  of  Cleveland  to  evaluate   the
antiangiogenic  effects of thalidomide  in blindness due  to age-related macular
degeneration.
 
    Although not approved for  sale in the United  States, thalidomide has  been
used  as an  investigational agent  to treat  a limited  number of  patients for
leprosy and other diseases and is being developed by other companies for various
disease indications. See "-- Government Regulation."
 
    ANGIOSTATIN-TM- PROTEIN.  The Company is developing Angiostatin-TM-  protein
as a potential long-term cancer therapeutic to prevent metastatic disease and as
a  therapy  for primary  tumors. Metastatic  tumor growth  is attributed  to the
implantation and growth of tumor cells at secondary sites. These tumor cells are
released by a primary  tumor, or are released  into circulation during  surgical
removal  of the  primary tumor.  Although surgeons  generally remove significant
amounts of healthy tissue surrounding the tumor, in many cases "seed cells" have
already escaped the primary tumor and are circulated through the body until they
become embedded elsewhere.  It has been  observed that in  certain cases,  these
seed  cells, or metastases, do not vascularize  and grow while the primary tumor
is in place. However, after the  primary tumor is removed, secondary  metastatic
tumors often grow rapidly.
 
    In Company-sponsored research at Children's Hospital, a substance associated
with  primary tumors was identified which appears to prevent vascularization and
growth of metastatic tumors. Based upon such research, the Company believes that
the primary tumor secretes an enzyme  that cleaves plasminogen, a known  protein
associated with blood clotting, into a smaller, previously undiscovered protein.
The  Children's Hospital  team isolated  and identified  the protein,  which the
Company named Angiostatin-TM- protein, and the Company has cloned and  expressed
the  gene  that  codes  for  Angiostatin-TM-  protein.  In  preclinical studies,
including the  murine  Lewis  Lung  Carcinoma  metastatic  model,  it  has  been
demonstrated  that  Angiostatin-TM- protein  inhibits  the growth  of metastatic
tumors derived  from  carcinomas  and  sarcomas.  In  addition,  Angiostatin-TM-
protein  was shown to reduce the size  of primary murine carcinomas and sarcomas
as well as  human prostate, breast  and colon cancers  grown in  immunodeficient
mice.   The  Company  and  Bristol-Myers   are  addressing  additional  required
preclinical studies,  while  manufacturing Angiostatin-TM-  protein  in  limited
quantities.
 
    The  Company  currently  anticipates  that  Angiostatin-TM-  protein,  as an
endogenous angiogenesis inhibitor, would be  administered as an adjunct  therapy
after   diagnosis   and  sustained   thereafter.   The  Company   believes  that
Angiostatin-TM-protein may  also be  effective  in inhibiting  other  angiogenic
diseases  such as  diabetic retinopathy  and macular  degeneration, although the
Company has not conducted any research to  date in these areas. The Company  has
obtained  an  exclusive license  from  Children's Hospital  to  this technology,
including rights to  patent applications  filed on  Angiostatin-TM- protein  and
related technology.
 
    OTHER ANTIANGIOGENESIS RESEARCH
 
    The Company maintains an internal discovery and development program and also
continues to sponsor and support research at Children's Hospital on angiogenesis
technologies with the aim of developing antiangiogenesis products in addition to
Angiostatin-TM- protein, thalidomide and thalidomide analogs. To the extent that
additional  antiangiogenesis therapeutics  are developed  at Children's Hospital
and licensed  by the  Company, Bristol-Myers  has a  right of  first refusal  to
sublicense  from  the  Company  such technologies.  See  "--  Collaborations and
License Agreements." The Company's  research in these  areas is currently  early
stage,  although  the Company  and Children's  Hospital have  identified several
endogenous proteins and compounds  with angiogenic or antiangiogenic  properties
that  may be candidates  for further development.  The Company intends  to use a
portion of  the proceeds  of  this offering  to  fund early-stage  internal  and
sponsored research on angiogenesis technologies. See "Use of Proceeds."
 
                                       24
<PAGE>
ENTREMED'S CELL PERMEATION TECHNOLOGY
 
    OVERVIEW
 
    The  Company is applying its expertise in  the role of blood function to the
development of a  cell permeation  technology that may  facilitate the  delivery
into  blood cells  of drugs,  genes or  other therapeutic  agents that otherwise
would not readily diffuse  through the cell membrane.  To date, the Company  has
focused  its  cell  permeation research  on  a  method of  enhancing  the oxygen
delivery capabilities of blood.
 
    Human blood is comprised  of four components: red  blood cells, white  blood
cells,  plasma  and platelets.  The principal  functions of  human blood  are to
transport oxygen  and  nutrients to  tissues,  carry waste  products  away  from
tissues  and  defend  the  body against  infection.  Hemoglobin,  a protein-iron
molecule contained within red  blood cells, is  responsible for carrying  oxygen
from  the lungs to tissues  throughout the body. Tissues  and organs in the body
require oxygen to function  properly, and oxygen deficiency  may lead to  tissue
damage or death. In human blood, each hemoglobin molecule carries four molecules
of  oxygen, but releases  only one. It  has been proposed  that IHP, a naturally
occurring plant  chemical,  may enhance  the  oxygen releasing  capabilities  of
hemoglobin  by allowing the  release of three oxygen  molecules. The theory that
IHP could enhance the oxygen releasing capacity of hemoglobin has been  proposed
for several years. Scientists have observed that a molecule similar to IHP found
in  the  hemoglobin  of birds  is  more  efficient at  releasing  oxygen  than a
corresponding molecule  (2,3  diphosphoglycerate, or  2,3  DPG) found  in  human
hemoglobin.  However, IHP does not readily  diffuse through the cell membrane of
human red blood cells  and previous techniques used  to introduce IHP into  such
red  blood  cells have  experienced significant  problems  and have  resulted in
substantial cell damage.
 
    The Company's research  has led  to the  development of  a prototype  device
designed  to introduce IHP into red blood cells without significant cell damage.
The Company intends to develop this application as a therapeutic in such chronic
and acute diseases as  angina, congestive heart  failure, heart attacks,  stroke
and  other diseases  involving inadequate circulation  or respiratory functions.
Existing methods of treatment for  these diseases, including surgical  remedies,
drug  therapies  and non-surgical  devices, treat  such  diseases by  seeking to
increase blood  flow,  rather  than  increasing  the  blood's  oxygen  releasing
capacity.  In addition, unlike blood that is  stored in blood banks, which loses
its capacity to  deliver oxygen  for approximately 12  to 24  hours following  a
transfusion,  blood treated with  IHP may be  able to release  oxygen to tissues
more rapidly  following  transfusion. The  Company  intends to  investigate  the
application of IHP-treated blood for storage in blood banks. Because IHP-treated
blood may release more oxygen to tissues than untreated human blood, it may also
be  possible that  a smaller  amount of IHP-treated  blood can  be transfused to
obtain equivalent tissue oxygenation.
 
    With the exception of  IHP-treated blood, the Company  has not yet  explored
any  other applications of its cell permeation technology. Potential therapeutic
candidates will be selected based on an analysis of various disease  indications
and  related  market  potential,  the  likely  time  and  expense  required  for
development and adaptation of the  core technology for the specific  application
and  the interest of potential  strategic partners. Potential product candidates
may  be  reformulations  of  existing  compounds  approved  by  the  FDA   where
enhancement  of  delivery  through  blood cell  membranes  is  believed  to have
increased clinical value compared  to existing methods.  The Company intends  to
use  a  portion  of  the  proceeds of  this  offering  to  investigate potential
applications of this technology. See "Use of Proceeds."
 
    DEVICE FOR OXYGEN ENHANCED BLOOD DELIVERY
 
    The Company has  constructed a  prototype device designed  to introduce  IHP
molecules  into red  blood cells,  which may enhance  the delivery  of oxygen to
tissues and organs. The device permits red blood cells drawn from patients to be
separated from plasma and treated with IHP in a disposable flow  electroporation
chamber. The flow electroporation chamber combines the separated red blood cells
 
                                       25
<PAGE>
with  IHP and, through an electrical charge, renders the red blood cell membrane
permeable, permitting IHP  to pass through  the cell membrane  and combine  with
hemoglobin. IHP-treated blood is then ready for infusion into the patient or for
storage for later infusion.
 
    The  Company is sponsoring contract  research and development on IHP-treated
blood. An initial prototype flow electroporation device has been constructed and
the accompanying reagents  have been developed,  although design activities  are
ongoing  and there can be no assurance  that a clinically acceptable device will
be completed. Following  completion of  a clinically  acceptable prototype,  the
Company   intends  to   conduct  preclinical  toxicology   studies  required  to
demonstrate the safety and efficacy of IHP-treated red blood cells in  enhancing
the delivery of oxygen to tissues in relevant disease states.
 
    The  Company's flow electroporation technology is based on Company sponsored
research conducted  at the  CBRL.  In November  1992,  the Company  obtained  an
exclusive worldwide license to this technology from the CBRL and a United States
patent  application for the device and method for introducing IHP into red blood
cells was filed in March 1993.  Device and disposable component engineering  and
development  has been and continues to  be conducted by a contract manufacturer,
which is also expected to provide pilot manufacturing capabilities.
 
    The Company is  in discussions with  several major pharmaceutical  companies
and  is seeking to enter into collaborative arrangements with corporate partners
to develop and commercialize the Company's cell permeation technology, which may
cover specific product candidates or disease indications. However, there can  be
no  assurance that any  such agreements will  be entered into  with any of these
companies or any potential partner  or that the terms  of any agreement will  be
favorable to the Company. See "-- Manufacturing and Marketing."
 
COLLABORATIONS AND LICENSE AGREEMENTS
 
    GENERAL.   The Company  intends to continue  to develop in-licensed products
and sponsored research programs and  to enter into collaborations and  licensing
agreements  with corporate  partners for product  development, manufacturing and
marketing. The  Company  believes  that  it will  be  necessary  to  enter  into
collaborative  arrangements  with  other  companies in  the  future  to develop,
commercialize, manufacture and market its cell permeation technology, as well as
any additional products or technologies it may acquire or develop.
 
    BRISTOL-MYERS COLLABORATION.  In December 1995, the Company entered into the
Bristol-Myers Collaboration  for  the development  of  certain  antiangiogenesis
products.  The  Bristol-Myers Collaboration  provides for  a five  year research
program, the grant  to Bristol-Myers of  an exclusive license  to the  Company's
thalidomide, thalidomide analogs and Angiostatin-TM- protein technologies and an
equity investment in the Company by Bristol-Myers.
 
   
    During  the  five year  research  term, the  Company  has agreed  to conduct
research and  Bristol-Myers  has  agreed  to support  and  fund  such  research.
Bristol-Myers  has  agreed to  provide funding  of  $18,350,000, payable  in ten
semi-annual payments of $1,835,000. In addition, Bristol-Myers has agreed to pay
an additional $730,000 to reimburse the Company for ongoing thalidomide clinical
studies, one-half  of  which has  been  paid and  the  remainder is  payable  in
December  1996. Bristol-Myers  also paid  to the  Company $1,000,000  in license
fees, a portion  of which  was paid to  Children's Hospital,  and $2,500,000  in
consideration of know-how and research and development performed by the Company.
    
 
    The  Company  granted Bristol-Myers  an exclusive  worldwide royalty-bearing
license to  make,  use and  sell  products that  are  based upon  the  Company's
Angiostatin-TM-   protein,  thalidomide  and  thalidomide  analog  technologies.
Bristol-Myers has  a  right  to  sublicense, and  has  undertaken  to  secure  a
sublicense   to  develop   thalidomide-related  products   for  ophthalmological
indications, unless Bristol-Myers reasonably believes that the dosage or  method
of   administration  will  not  be   significantly  different  from  oncological
indications. Any  failure  or  delay  by Bristol-Myers  to  enter  into  such  a
sublicense  may substantially  limit or  preclude the  commercial development of
these applications.
 
                                       26
<PAGE>
Bristol-Myers also received a five year  right of first refusal with respect  to
the development of any technology licensed or to be licensed by the Company from
Children's Hospital in the field of antiangiogenic therapeutics.
 
    The  Bristol-Myers Collaboration also provides  for royalties to the Company
based on the net sales price of products sold by Bristol-Myers. With respect  to
any  product that is derived from  Angiostatin-TM- protein, the royalty shall be
15% of  net  sales,  subject to  a  reduction  to  no less  than  10%  based  on
manufacturing  costs. With respect to any  product derived from thalidomide, the
royalty shall be 8% and, with respect to thalidomide analogs, the royalty  shall
range  from 8% to 12.5%  based on sales volume. In  the case of thalidomide, the
royalties shall be subject to reduction based on competitive factors.
 
    In addition, the Company may be entitled to receive additional payments  for
each  product  category  based upon  the  achievement of  defined  and primarily
late-stage clinical development  and regulatory filing  milestones. While  there
can  be no  assurance that  these milestones  will be  reached, these additional
payments could total $32,000,000. Up to $9,000,000 of the milestone payments for
products related to thalidomide and thalidomide analogs and up to $4,000,000  of
the   milestones  for  products  related  to  Angiostatin-TM-  protein  will  be
creditable against any royalties that may become payable by Bristol-Myers to the
Company, although the cumulative  amount of credits in  any year may not  exceed
50%  of the aggregate royalties otherwise  payable. The Company retained certain
co-promotion rights if Bristol-Myers elects to seek a co-promotion partner  with
respect  to  any  products  covered  by  the  collaboration.  The  Bristol-Myers
Collaboration may be terminated by Bristol-Myers for any reason upon six  months
notice without any further liability for future payments.
 
   
    Upon  execution of the  Bristol-Myers Collaboration, Bristol-Myers purchased
541,666 shares of the Company's Common Stock for $12.00 per share and agreed  to
purchase  an  additional  $5,000,000 of  Common  Stock  at the  closing  of this
offering in a private placement at the initial public offering price per  share.
The  Company also  issued to Bristol-Myers  a warrant,  exercisable for one-year
from the date of this Prospectus, to purchase up to $10,000,000 of Common  Stock
at  an exercise  price per share  equal to  150% of the  initial public offering
price per share. The Company  has granted to Bristol-Myers certain  registration
rights with respect to all of these shares. See "Description of Capital Stock --
Registration Rights."
    
 
    ACADEMIC  COLLABORATIONS.  In addition to its in-house research program, the
Company collaborates with several academic  institutions to support research  in
areas   of  the  Company's  product  development  interests.  Usually,  research
supported at  outside academic  institutions is  performed in  conjunction  with
additional  in-house  research.  Often,  the  faculty  members  responsible  for
supervision  of  the  research  performed  at  the  academic  institution   will
participate further as consultants to the Company's in-house effort.
 
    Typically  under these arrangements, the Company agrees to fund the research
it has chosen to support with a  specified budget over a specified time  period,
usually  one to three years. In return, the Company usually obtains an exclusive
license, with the right to grant  sublicenses, and the right to further  develop
and  market products  that arise  out of  the technology  being supported. Under
several of these licenses, the Company is required to meet specified  milestones
or  diligence requirements in order to  retain its license of such technologies.
There can be  no assurance that  the Company will  satisfy these milestones  and
diligence  requirements  and be  able to  retain such  licenses. In  addition to
providing research support, the Company usually is required to pay royalties  to
the  academic institution on  sales, if any, of  any licensed products resulting
from such research. The  Company in most instances  files and prosecutes  patent
applications on behalf of the institutions.
    The Company's primary academic collaboration is with Children's Hospital. In
September  1993, the  Company entered into  a sponsored  research agreement with
Children's Hospital to support research conducted under the direction of Dr.  M.
Judah  Folkman on the role of angiogenesis in pathological conditions. Under the
agreement, as amended in  August 1995, the Company  agreed to pay to  Children's
Hospital   $11,000,000,  of  which  $5,000,000  was  paid  through  April  1996,
$1,000,000
 
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<PAGE>
is due on October 1, 1996 and the remainder is due in equal semi-annual payments
of $1,000,000  until April  1,  1999. The  Company  also granted  to  Children's
Hospital  options to acquire 83,334 shares of  Common Stock at an exercise price
of $6.00  per  share and  additional  options to  acquire  50,000 shares  at  an
exercise  price of $6.375 per share. The Company obtained an exclusive option to
negotiate an  exclusive, worldwide,  royalty-bearing license  to any  technology
resulting  from  the research  at Children's  Hospital in  areas covered  by the
agreement. The Company received a right to sublicense the licensed technologies,
although the  Company agreed  to pay  to Children's  Hospital a  portion of  all
sublicensing  payments, which  do not include  payments to  support research and
development by the Company or equity investments in the Company. The Company has
also received certain  rights of  first refusal to  certain additional  research
projects  and  any new  project opportunities  arising  from Dr.  Folkman's core
laboratory activities.
    The Company exercised its option in  May 1994 to obtain exclusive  worldwide
licenses  to  certain  oral  antiangiogenesis  technology  (thalidomide  and its
analogs),  cancer   diagnostic  and   prognostic  technology,   and   endogenous
antiangiogenesis  technology (Angiostatin-TM- protein). These license agreements
provide for certain milestone payments by the Company to Children's Hospital  as
well  as royalties based  on sales, if  any, of any  products developed from the
licensed technologies.  The milestone  payments aggregate  $2,650,000, of  which
$290,000  has been paid through March 31,  1996, and are based upon license fees
and the achievement of regulatory approvals. See "-- Angiogenesis Program."
 
   
    OTHER COLLABORATIVE ARRANGEMENTS.   The  Company is  sponsoring research  at
Innovative  Therapeutics, Inc. ("ITI"), a company that is performing early-stage
research on  methods to  treat  disease by  stimulating cellular  immunity.  The
methods  under  development  pursuant  to this  sponsored  research  program are
designed to target specific diseases by the administration of synthetic peptides
or recombinant proteins that  mimic proteins which  occur naturally during  that
particular  disease. These therapeutic agents  are designed to initiate cellular
immune responses exclusively, without affecting humoral immunity. Through  March
31,  1996,  the Company  has paid  ITI approximately  $682,500 pursuant  to this
collaboration.
    
 
   
    The Company and ITI  have agreed to preliminary  terms regarding a  proposed
transaction  whereby a  subsidiary to be  formed by the  Company ("Newco") would
acquire substantially all of the assets of ITI in exchange for 15% of the equity
of Newco and a research funding commitment by the Company. The terms contemplate
an equity investment by  the Company in Newco  of $250,000 and research  funding
for this 85% owned subsidiary of an aggregate of $1,600,000 during the first two
years,  with an additional $1,500,000  to be provided at  the sole option of the
Company during the third  year. The acquisition is  subject to the execution  of
definitive  agreements,  and  there  can  be  no  assurance  that  the  proposed
transaction will be completed on the terms set forth above or at all.
    
 
    The Company  intends to  continue  to support  and  fund research  at  other
companies  or academic or  other institutions in selected  areas in exchange for
rights to  technologies and  products derived  from such  sponsored research  or
equity  positions in such  companies. The Company expects  to focus on sponsored
research in areas in which  it has existing expertise  or where a strong  market
opportunity  is perceived. The Company may establish subsidiaries to develop and
commercialize promising technologies or  products generated from this  research,
which  may  create  opportunities  for  separately  financing  and  managing new
development programs. The  Company may  use a portion  of the  proceeds of  this
offering  to  fund  sponsored  research  by  other  organizations.  See  "Use of
Proceeds."
 
COMPETITION
 
   
    Competition  in  the  pharmaceutical,  biotechnology  and  biopharmaceutical
industries  is intense and  based significantly on  scientific and technological
factors, the  availability of  patent and  other protection  for technology  and
products,  the  ability  and  length of  time  required  to  obtain governmental
approval  for  testing,   manufacturing  and  marketing   and  the  ability   to
commercialize  products  in a  timely  fashion. Moreover,  the biopharmaceutical
industry is characterized by  rapidly evolving technology  that could result  in
the  technological obsolescence  of any products  developed by  the Company. The
    
 
                                       28
<PAGE>
Company competes with  many specialized  biopharmaceutical firms, as  well as  a
growing number of large pharmaceutical companies that are applying biotechnology
to  their  operations.  Many  biopharmaceutical  companies  have  focused  their
development  efforts   in  the   human  therapeutics   area,  and   many   major
pharmaceutical  companies  have  developed  or  acquired  internal biotechnology
capabilities  or  made  commercial  arrangements  with  other  biopharmaceutical
companies.  These  companies,  as well  as  academic  institutions, governmental
agencies and private research  organizations, also compete  with the Company  in
recruiting and retaining highly qualified scientific personnel and consultants.
 
    The  Company's  competition  will be  determined  in part  by  the potential
indications for which the  Company's compounds may  be developed and  ultimately
approved  by regulatory authorities. The Company  is relying on Bristol-Myers to
commercialize the  licensed  antiangiogenesis  products  and,  accordingly,  the
success of these products in the target indications of cancer and blindness will
depend  in significant part on Bristol-Myers'  efforts and ability to compete in
these markets. The  success of  the Bristol-Myers Collaboration  will depend  in
part    upon   Bristol-Myers'   own   competitive,   marketing   and   strategic
considerations, including the relative advantages of alternative products  being
developed  and  marketed  by  Bristol-Myers and  its  competitors.  For example,
Bristol-Myers currently markets cancer therapeutics, which would be  competitive
with any antiangiogenic products developed under the Bristol-Myers Collaboration
to  treat cancer. Bristol-Myers has a right to sublicense, and has undertaken to
secure a sublicense to develop thalidomide-related products for ophthalmological
indications, unless Bristol-Myers reasonably believes that the dosage or  method
of   administration  will  not  be   significantly  different  from  oncological
indications. Any  failure  or  delay  by Bristol-Myers  to  enter  into  such  a
sublicense  may substantially  limit or  preclude the  commercial development of
these applications. See "-- Collaborations and License Agreements."
 
   
    The Company is  aware of companies  and research institutions  investigating
the  role of  angiogenesis generally  and specifically  as it  may be  useful in
developing therapeutics to treat various diseases associated with abnormal blood
vessel growth. In studies available to date, these angiogenetic inhibitors  have
shown  varying effectiveness in inhibiting angiogenesis and differing degrees of
bioavailability and  toxicity.  Significant  further  preclinical  and  clinical
development  of these  products is  needed prior  to an  assessment of  the more
significant competitive  product  candidates  in  the  antiangiogenesis  disease
indications targeted by the Company.
    
 
    The  Company is aware of other  companies developing thalidomide and certain
of its  chemical  analogs for  various  disease indications,  including  Celgene
Corporation,  for the treatment of AIDS-related  cachexia (or wasting) and mouth
ulcers,  and  Andrulis  Pharmaceuticals,  for  diabetes.  Although  the  Company
believes that its patent rights, if granted, would preclude another company from
marketing  thalidomide for antiangiogenic indications, there can be no assurance
that any patent will issue or afford meaningful protection.
 
    A substantial number of companies utilize or are developing cell  permeation
or  drug  delivery  technologies and  competition  for the  development  of drug
delivery products is  intense, although  the Company's  focus is  on blood  cell
permeation.  The  Company  is  aware  of  at  least  one  other  company,  Allos
Therapeutics, Inc., that is engaged  in early-stage research regarding a  method
to  acutely increase  the oxygen-releasing  capacity of  hemoglobin for treating
cancer. The  Company  also anticipates  that  IHP-treated blood  (which  is  not
technically  a blood  replacement), will compete  for use  in blood transfusions
with readily available products, including whole human blood or packed red blood
cells, and products under development, such as blood substitutes.
 
    Many of the Company's existing  or potential competitors have  substantially
greater  financial, technical  and human resources  than the Company  and may be
better equipped to develop, manufacture  and market products. In addition,  many
of  these competitors have extensive experience in preclinical testing and human
clinical  trials  and  in  obtaining  regulatory  approvals.  The  existence  of
 
                                       29
<PAGE>
competitive  products, including products or treatments  of which the Company is
not aware, or products or  treatments that may be  developed in the future,  may
adversely  affect the  marketability of products  which may be  developed by the
Company.
 
MANUFACTURING AND MARKETING
 
    The Company's  strategy is  to enter  into collaborative  arrangements  with
pharmaceutical  and  other  companies  for  the  development,  manufacturing and
marketing of products  requiring broad marketing  capabilities and for  overseas
marketing.  These  collaborators are  generally expected  to be  responsible for
funding or reimbursing all or a portion of the development costs, including  the
costs  of clinical  testing necessary  to obtain  regulatory clearances  and for
commercial scale  manufacturing, in  exchange  for exclusive  or  semi-exclusive
rights  to  market specific  products in  particular geographic  territories. To
date,  the  Company   has  entered  into   one  collaboration  agreement,   with
Bristol-Myers,   relating  to  certain  of  its  antiangiogenesis  technologies.
However, the Company  may, in  the future, consider  manufacturing or  marketing
certain  products directly and to co-promote  certain products if it believes it
is appropriate  under  the  circumstances.  The Company  has  no  experience  in
manufacturing  or marketing products on a commercial scale and does not have the
resources to manufacture or market  by itself on a  commercial scale any of  its
product   candidates.  In  the   event  the  Company   decides  to  establish  a
manufacturing facility, the Company  will require substantial additional  funds,
and  will be  required to  hire and  train significant  additional personnel and
comply with the extensive  "good manufacturing practice" regulations  applicable
to such a facility.
 
PATENTS AND PROPRIETARY RIGHTS
 
    The  Company's success will depend  in part on its  ability to obtain patent
protection for its products,  both in the United  States and abroad. The  patent
position  of  biotechnology and  pharmaceutical companies  in general  is highly
uncertain and  involves complex  legal and  factual questions.  The Company  has
filed  eight  U.S.  patent applications  covering  Angiostatin-TM-  protein, DNA
coding for the Angiostatin-TM- protein, the use of Angiostatin-TM- protein as  a
therapeutic  agent and the use of Angiostatin-TM- protein as a diagnostic agent.
The Company also has  filed three U.S. patent  applications covering the use  of
the  thalidomide molecule and thalidomide analogs as an antiangiogenic agent for
the treatment of  a wide  variety of diseases  that are  caused by  uncontrolled
angiogenesis.  These  patent  applications also  include  composition  of matter
coverage for certain thalidomide analogs. The  Company has also filed four  U.S.
patent  applications covering the  device and method  for introducing substances
into  cells  by  flow  electroporation.  These  patent  applications  cover  the
electroporation  chamber in the  device, the overall  electroporation device and
the treatment of a wide variety of  diseases using cells that have been  treated
in  the electroporation  device. Patent  applications corresponding  to the U.S.
patent applications have been filed in Europe, Japan, Canada and other  selected
countries.  The Company has  also filed intent-to-use  trademark applications in
the U.S.  Patent  and  Trademark  Office for  the  marks  "Angiostatin-TM-"  and
"EntreMed."
 
    There  can be no assurance that any  patents will be granted or that patents
issued to the Company  will not be challenged,  invalidated or circumvented,  or
that  the rights granted  thereunder will provide  proprietary protection to the
Company.  Furthermore,  there  can  be   no  assurance  that  others  will   not
independently  develop similar products or, if patents are issued to the Company
or its collaborators, will not design around such patents.
 
    Furthermore, the  enactment  of  the legislation  implementing  the  General
Agreement  on Trade and Tariffs has resulted in certain changes to United States
patent laws that became  effective on June  8, 1995. Most  notably, the term  of
patent  protection for patent applications filed on  or after June 8, 1995 is no
longer a period of  seventeen years from the  date of grant. The  new term of  a
United  States patent will commence on the date of issuance and terminate twenty
years from the earliest  effective filing date of  the application. Because  the
time  from filing to issuance of  biotechnology patent application is often more
than three  years, a  twenty-year term  from the  effective date  of filing  may
 
                                       30
<PAGE>
result  in  a  substantially  shortened term  of  patent  protection,  which may
adversely impact the  Company's patent  position. If  this change  results in  a
shorter  period of  patent coverage, the  Company's business  could be adversely
affected to  the extent  that the  duration and  level of  the royalties  it  is
entitled  to receive from a collaborative partner is based on the existence of a
valid patent.
 
    The Company's potential products may  conflict with patents which have  been
or  may be granted to competitors,  universities or others. As the biotechnology
industry expands  and more  patents  are issued,  the  risk increases  that  the
Company's  potential products  may give  rise to  claims that  they infringe the
patents of others.  Such other  persons could  bring legal  actions against  the
Company  claiming damages and seeking  to enjoin clinical testing, manufacturing
and marketing of the affected products.  If any such actions are successful,  in
addition  to any potential liability for  damages, the Company could be required
to obtain a license in order to  continue to manufacture or market the  affected
products.  There can be no assurance that  the Company would prevail in any such
action or  that  any  license required  under  any  such patent  would  be  made
available  on acceptable terms,  if at all.  If the Company  becomes involved in
litigation, it could  consume a substantial  portion of the  Company's time  and
resources.
 
    Composition  of matter patent  protection is not  available for thalidomide.
The Company  is aware  of at  least two  other issued  patents covering  certain
non-antiangiogenic  uses of thalidomide. Although  the Company believes that the
claims in such  patents will not  interfere with the  Company's proposed use  of
thalidomide, there can be no assurance that the holders of such patents will not
be   able   to   exclude  the   Company   from  using   thalidomide   for  other
non-antiangiogenic uses of thalidomide.
 
    The Company also relies on trade secret protection for its confidential  and
proprietary  information. However,  trade secrets  are difficult  to protect and
there  can  be  no  assurance   that  others  will  not  independently   develop
substantially  equivalent  proprietary information  and techniques  or otherwise
gain access to the Company's trade secrets or disclose such technology, or  that
the Company can meaningfully protect its rights to unpatented trade secrets.
 
    The  Company requires its  employees, consultants and  advisors to execute a
confidentiality agreement upon the commencement  of an employment or  consulting
relationship  with  the Company.  The  agreements generally  provide  that trade
secrets and  all inventions  conceived by  the individual  and all  confidential
information  developed or made  known to the  individual during the  term of the
relationship shall be the  exclusive property of the  Company and shall be  kept
confidential   and  not   disclosed  to   third  parties   except  in  specified
circumstances. There can be  no assurance, however,  that these agreements  will
provide  meaningful protection for the  Company's proprietary information in the
event of unauthorized use or disclosure of such information.
 
GOVERNMENT REGULATION
 
    The Company's development, manufacture and potential sale of therapeutics is
subject to  extensive  regulation  by United  States  and  foreign  governmental
authorities.
 
    REGULATION  OF  PHARMACEUTICAL PRODUCTS.   Products  being developed  by the
Company may be regulated by the FDA as drugs or biologics or, in some cases,  as
medical  devices. New  drugs are subject  to regulation under  the Federal Food,
Drug, and Cosmetic Act, and biological products, in addition to being subject to
certain provisions of that  Act, are regulated under  the Public Health  Service
Act.   The  Company  believes  that  drug   products  developed  by  it  or  its
collaborators will be regulated either as  biological products or as new  drugs.
Both  statutes and  the regulations  promulgated thereunder  govern, among other
things, the testing, manufacturing, safety, efficacy, labeling, storage,  record
keeping,  advertising and other promotional practices involving biologics or new
drugs, as the case  may be. FDA  approval or other  clearances must be  obtained
before  clinical testing, and  before manufacturing and  marketing, of biologics
and drugs.
 
    Obtaining FDA approval  has historically  been a costly  and time  consuming
process.  Generally, in order to gain FDA pre-market approval, a developer first
must conduct pre-clinical studies in the
 
                                       31
<PAGE>
laboratory and in  animal model systems  to gain preliminary  information on  an
agent's  efficacy  and to  identify any  safety problems.  The results  of these
studies are  submitted  as  a  part  of  an  investigational  new  drug  ("IND")
application,  which  the FDA  must  review before  human  clinical trials  of an
investigational  drug  can  start.  The  IND  application  includes  a  detailed
description of the clinical investigations to be undertaken.
 
    In order to commercialize any products, the Company or its collaborator must
sponsor  and file an  IND and be  responsible for initiating  and overseeing the
clinical studies  to  demonstrate the  safety,  efficacy and  potency  that  are
necessary  to  obtain  FDA  approval  of  any  such  products.  For  Company  or
collaborator-sponsored INDs, the Company or its collaborator will be required to
select qualified investigators (usually physicians within medical  institutions)
to   supervise  the  administration  of  the   products,  and  ensure  that  the
investigations are conducted and monitored  in accordance with FDA  regulations,
including  the general investigational plan and  protocols contained in the IND.
Clinical trials  are normally  done in  three phases,  although the  phases  may
overlap.  Phase I trials are concerned primarily with the safety and preliminary
effectiveness of the drug,  involve fewer than 100  subjects, and may take  from
six  months to  over one year.  Phase II  trials normally involve  a few hundred
patients and are designed primarily to demonstrate effectiveness in treating  or
diagnosing  the disease  or condition for  which the drug  is intended, although
short-term side effects and risks in people whose health is impaired may also be
examined. Phase III trials are expanded  clinical trials with larger numbers  of
patients which are intended to evaluate the overall benefit-risk relationship of
the  drug and to gather additional information for proper dosage and labeling of
the drug. Clinical trials generally take two to five years to complete, but  may
take  longer. The FDA receives reports on the progress of each phase of clinical
testing, and  it may  require the  modification, suspension,  or termination  of
clinical  trials  if  it concludes  that  an  unwarranted risk  is  presented to
patients.
 
    If clinical trials of a new product are completed successfully, the  sponsor
of the product may seek FDA marketing approval. If the product is regulated as a
biologic,  the FDA will  require the submission  and approval of  both a Product
License Application  ("PLA") and  an  Establishment License  Application  before
commercial  marketing of  the biologic.  If the product  is classified  as a new
drug, the Company  must file a  New Drug  Application ("NDA") with  the FDA  and
receive  approval before commercial marketing  of the drug. The  NDA or PLA must
include detailed information about the drug and its manufacture and the  results
of product development, preclinical studies and clinical trials. The testing and
approval  processes  require substantial  time and  effort and  there can  be no
assurance that any approval will be granted  on a timely basis, if at all.  NDAs
and PLAs submitted to the FDA can take, on average, two to five years to receive
approval.  If questions arise  during the FDA review  process, approval can take
more than five years. Notwithstanding the  submission of relevant data, the  FDA
may  ultimately  decide that  the NDA  or  PLA does  not satisfy  its regulatory
criteria for approval and deny approval or require additional clinical  studies.
In addition, the FDA may condition marketing approval on the conduct of specific
post-marketing studies to further evaluate safety and effectiveness. Even if FDA
regulatory  clearances are obtained, a marketed  product is subject to continual
review, and later discovery of previously unknown problems or failure to  comply
with  the applicable regulatory  requirements may result  in restrictions on the
marketing of a product or withdrawal of  the product from the market as well  as
possible civil or criminal sanctions.
 
   
    Thalidomide  is  regulated  by  the FDA's  Center  for  Drug  Evaluation and
Research. Although not approved for sale in the U.S., thalidomide has been  used
as an investigational agent to treat thousands of patients for leprosy and other
diseases.  EntreMed has filed an IND application  and started Phase II trials in
macular degeneration,  a  leading  cause  of blindness,  and  expects  that  the
analysis  of  these results  could  determine whether  Phase  III trials  may be
attempted. The  National Cancer  Institute in  collaboration with  EntreMed  and
Bristol-Myers  has begun Phase  II trials in breast  cancer, prostate cancer and
Kaposi's sarcoma. It is expected that  future cancer trials may be dependent  on
the  results of  these studies.  Thalidomide must  meet the  standard regulatory
requirements of any new drug, and  successful Phase III clinical trials will  be
necessary to form the basis of an NDA.
    
 
                                       32
<PAGE>
    Analogs  of thalidomide  may be  regulated as  new chemical  entities by the
FDA's Center for Drug Evaluation and  Research. Although these compounds are  in
the  discovery phase of research,  it is expected that  as new chemical entities
are discovered complete preclinical toxicology studies will be required prior to
studies  in  humans.   The  remainder  of   the  developmental  and   regulatory
requirements will be similar to that of any new drug.
 
    Angiostatin-TM-  protein, a  naturally occurring substance,  is considered a
biologic and will be regulated by the FDA's Center for Biologics Evaluation  and
Research.  As a  genetically engineered and  endogenous protein, Angiostatin-TM-
protein will face unique and specific regulation hurdles, such as those  related
to  the manufacture of the product and the  behavior of the product in the body.
The regulatory requirements  for recombinant  proteins have  been developed  for
other   endogenous  molecules  (e.g.,  Epogen,  Neupogen  and  Interferons)  and
Angiostatin-TM-protein is  expected  to  follow  these  established  guidelines.
Successful  preclinical studies and Phase I, II and III trials will be necessary
to form the basis for a PLA.
 
    The cell  permeation  technology,  and specifically  IHP-treated  red  blood
cells, will likely be regulated by the FDA's Center for Biologics Evaluation and
Research.  The Company  anticipates that the  FDA will view  the IHP-treated red
blood cells (rather than IHP itself) as the regulated product. In addition,  the
device  used to  insert IHP  into the red  blood cells  may be  regulated by the
Center for Biologics Evaluation and Research under the medical device provisions
of the  Federal Food,  Drug and  Cosmetic  Act (described  below). It  would  be
expected  that the preclinical  and clinical trials necessary  for approval of a
PLA would also  be relevant  to the approval  of the  device. Historically,  the
FDA's  Office  of Blood  Research  and Review  has  had the  most  expertise and
experience in regulating blood,  apheresis equipment and disposables  associated
with the processing of human blood. Further development for IHP-treated blood is
expected  to follow  a similar  path to that  of any  therapeutic biologic, with
successful completion of  Phase I,  Phase II and  Phase III  trials required  to
precede the filing of a PLA. Because the cell permeation technology requires the
use  of red blood  cells produced from  humans, the Company  will be required to
comply  with,  or  to  contract  with  suppliers  that  comply  with,  stringent
regulation of blood component collection. That regulation is designed to protect
both   donors  and  recipients  of   blood  products  and  involves  significant
recordkeeping and other burdens.
 
    REGULATION OF DEVICES.   Any device products which  may be developed by  the
Company  are likely to  be regulated by  the FDA as  medical devices rather than
drugs. In addition, as noted, the device  used to insert IHP in blood cells  may
be  regulated as a medical device. The nature of the FDA requirements applicable
to such products depends on their classification by the FDA. A device  developed
by  the  Company  would  be  automatically classified  as  a  Class  III device,
requiring pre-market approval, unless the Company could demonstrate to the  FDA,
in   the  required  pre-market  notification  procedure,  that  the  device  was
substantially equivalent to an existing device that has been classified in Class
I or Class II or to a pre-1976  device that has not yet been classified. If  the
Company  were unable  to demonstrate such  substantial equivalence,  it would be
required to undertake the costly and time-consuming process, comparable to  that
for  new drugs, of conducting  preclinical studies, obtaining an investigational
device  exemption  to  conduct  clinical  tests,  filing  a  premarket  approval
application, and obtaining FDA approval.
 
    If  the  Company  could demonstrate  substantial  equivalence to  a  Class I
product, the "general controls" of the  Federal Food, Drug, and Cosmetic Act  --
chiefly  adulteration, misbranding, and good manufacturing practice requirements
- -- would nevertheless  apply. If substantial  equivalence to a  Class II  device
could  be  shown,  the  general  controls plus  "special  controls"  --  such as
performance standards, guidelines for safety and effectiveness, and  post-market
surveillance  -- would apply.  While demonstrating substantial  equivalence to a
Class I or Class II product is not as costly or time-consuming as the pre-market
approval process  for Class  III devices,  it  can in  some cases  also  involve
conducting  clinical tests to  demonstrate that any  differences between the new
device and devices already on the market do not affect safety or  effectiveness.
If substantial equivalence to a pre-1976
 
                                       33
<PAGE>
device  that has not yet been classified has been shown, it is possible that the
FDA would subsequently classify the  device as a Class  III device and call  for
the filing of premarket approval applications at that time. If the FDA took that
step,  then filing an application acceptable to  the FDA would be a prerequisite
to remaining on the market.
 
    If the FDA chooses  to regulate the device  (the electroporation device  and
disposable  flow chamber) used to insert IHP in blood cells as a medical device,
it is likely that the review process  will nevertheless occur in the Center  for
Biologics  Evaluation and  Research. It is  possible, however,  that such Center
would consult  with relevant  officials  in the  FDA's  Center for  Devices  and
Radiological  Health. Such  a consultation might  further delay  approval of the
device and thus of this technology.
 
    OTHER.  In addition to the foregoing, the Company's business is and will  be
subject  to  regulation  under  various state  and  federal  environmental laws,
including the Occupational Safety and Health Act, the Resource Conservation  and
Recovery  Act and the Toxic  Substance Control Act. These  and other laws govern
the Company's use,  handling and  disposal of various  biological, chemical  and
radioactive  substances  used in  and wastes  generated  by its  operations. The
Company believes that it is in material compliance with applicable environmental
laws and  that its  continued  compliance therewith  will  not have  a  material
adverse effect on its business. The Company cannot predict, however, whether new
regulatory  restrictions  on the  marketing  of biotechnology  products  will be
imposed by state or federal regulators and agencies.
 
EMPLOYEES
 
   
    As of May 15, 1996, the Company had 27 full-time employees, of which 19 were
in research and development and eight were in management and administration. The
Company  intends  to  hire  additional  personnel.  The  Company  also  utilizes
part-time  or temporary consultants on an as-needed basis. None of the Company's
employees is represented by a labor union and the Company believes its relations
with its employees are satisfactory.
    
 
PROPERTIES
 
    The Company currently occupies an  aggregate of approximately 11,600  square
feet  of office  space (approximately 8,250  square feet of  which is laboratory
space) in Rockville, Maryland  pursuant to a lease  expiring in April 2003.  The
lease provides for annual rent of approximately $215,000 during 1996, subject to
specified  annual increases.  See Note 4  of Notes to  Financial Statements. The
Company anticipates that its current facilities will be sufficient through 1996,
at which time it is  likely to require additional  or larger space. The  Company
has  not  yet  determined whether  to  lease  additional space  or  build  a new
facility, but expects to use proceeds of this offering to fund a portion of  the
costs relating to any such expansion. See "Use of Proceeds."
 
LEGAL PROCEEDINGS
 
   
    The Company is a party to certain litigation initiated in August 1995 in the
United  States District Court for the  Eastern District of Tennessee by Bolling,
McCool & Twist,  a consulting firm.  The suit  relates to a  claim for  services
rendered  in the approximate  amount of $50,000  and seeks a  finder's fee in an
unspecified amount in connection with the Bristol-Myers Collaboration. In  April
1996,  the  Company filed  a  motion to  compel discovery.  Due  to the  lack of
discovery and early stage of the  proceedings, the Company is unable to  predict
with  certainty  the eventual  outcome of  the lawsuit.  The Company  intends to
contest the action vigorously and believes that this proceeding will not have  a
material  adverse effect on the Company or on its financial statements, although
there can be no assurance that this will be the case.
    
 
                                       34
<PAGE>
                                   MANAGEMENT
 
EXECUTIVE OFFICERS AND DIRECTORS
 
    The  following  table  sets  forth  the names,  ages  and  positions  of the
executive officers and directors of the Company:
 
   
<TABLE>
<CAPTION>
NAME                                   AGE                         POSITION
- ---------------------------------      ---      -----------------------------------------------
<S>                                <C>          <C>
John W. Holaday, Ph.D. (1).......          50   Chairman of the Board, President, Chief
                                                 Executive Officer and Director
Carol A. Nacy, Ph.D. ............          48   Executive Vice President
Edward R. Gubish, Ph.D. .........          47   Vice President -- Regulatory and Clinical
                                                 Development
Leo Einck, Ph.D. ................          45   Vice President -- Extramural Programs
John C. Thomas, Jr. .............          42   Treasurer and Chief Financial Officer
Carl Alving, M.D. ...............          56   Director
Donald S. Brooks (2)(3)..........          60   Director
Bart Chernow, M.D. ..............          48   Director
Samuel R. Dunlap, Jr. (1)(2).....          46   Executive Advisor and Director
Mark C.M. Randall (3)............          33   Director
Leon E. Rosenberg, M.D. .........          63   Director
Wendell M. Starke (1)(2).........          54   Director
</TABLE>
    
 
- ------------------------
(1) Member of Executive Committee
 
(2) Member of Compensation Committee
 
(3) Member of Audit Committee
 
    JOHN W. HOLADAY, PH.D. is a co-founder of the Company and has served as  its
President  and Chief Executive Officer and a  director since August 1992 and its
Chairman of  the Board  since November  1995. Prior  thereto, from  May 1989  to
August 1992, he was a co-founder of Medicis Pharmaceutical Corp. where he served
as  Scientific Director, Senior Vice President  for Research and Development and
director. From 1968  to 1989, he  served at  the Walter Reed  Army Institute  of
Research, where he founded the Neuropharmacology Branch in 1980. He serves as an
officer  and fellow in several biomedical  societies and has authored and edited
numerous scientific  articles  in  journals  and  books.  His  current  academic
positions  include  Associate  Professor  of  Anesthesiology  and  Critical Care
Medicine and Senior  Lecturer in  Medicine at  The Johns  Hopkins University  of
Medicine,  Baltimore, Maryland; Adjunct Professor of Pharmacology and Psychiatry
at the Uniformed Services University School of Medicine, Bethesda, Maryland; and
Clinical Assistant Professor of Surgery at the University of Connecticut  Health
Center, Farmington, Connecticut.
 
   
    CAROL A. NACY, PH.D. joined the Company as Senior Vice President of Research
in December 1992 and became Executive Vice President in November 1995. From 1978
until  December 1992, Dr. Nacy was employed by the Walter Reed Army Institute of
Research, where she served in various capacities, including Project Director  of
Immunotherapy  and Infectious Diseases and Assistant  Chief of the Department of
Cellular Immunology since 1988.  Dr. Nacy currently serves  as the President  of
the  American Society of Microbiology. Her current academic appointments include
Catholic University and Howard University in Washington, D.C. Dr. Nacy serves as
an officer  of  international scientific  societies  and as  editor  of  several
scientific journals.
    
 
                                       35
<PAGE>
    EDWARD  R.  GUBISH, PH.D.  has  served as  Vice  President -  Regulatory and
Clinical Development of the Company since November 1995 and has been employed by
the Company since October 1993. From  1990 to September 1993, Dr. Gubish  served
as senior director of Regulatory Affairs for Baker Norton Pharmaceuticals (IVAX)
and  Fujisawa Pharmaceuticals. From 1986 to 1990,  Dr. Gubish served as Chief of
regulatory affairs for the  AIDS Division at the  National Institutes of  Health
and  as a scientific  and administrative contact for  sponsors of new biological
products and IND submissions for the, Center for Drugs and Biologics at the FDA.
 
    LEO EINCK, PH.D. has served as Vice President -- Extramural Programs of  the
Company  since November  1995. From  1985 to September  1993, Dr.  Einck was the
Director of  Operations  for  HEM  Pharmaceuticals, a  company  engaged  in  the
development  of biopharmaceutical  agents. From  1980 to  1985, Dr.  Einck was a
researcher in molecular biology at the National Institutes of Health.
 
    JOHN C. THOMAS, JR. has served  part-time as Chief Financial Officer of  the
Company since its inception in September 1991. Mr. Thomas has also served as the
Chief  Financial  Officer of  several  other companies,  including  Credit Depot
Corporation, a public  company engaged in  loan financing (from  August 1990  to
March  1993 and  from January 1995  until April  1996), Tapistron International,
Inc., a public company engaged in the development of technology for the  textile
industry  (from August  1991 until July  1995), and Sealite  Sciences, a private
biotechnology company (from June 1991 to March 1993). Mr. Thomas is a  certified
public accountant.
 
    CARL  ALVING, M.D. is a co-founder of the Company and has been a director of
the Company since August 1992. He has  been Chief of the Department of  Membrane
Biochemistry  at  the Walter  Reed Army  Institute of  Research since  1978. Dr.
Alving has been the inventor of a number of patented technologies in the  fields
of drug delivery and immunology.
 
    DONALD  S. BROOKS has been a director of the Company since April 1996. Since
July 1993, Mr. Brooks has been a  practicing attorney with the law firm  Carella
Byrne  Bain  Gilfillan Cecchi  Stewart &  Olstein,  Roseland, New  Jersey, which
represents the  Company  on  certain  matters. Prior  thereto,  Mr.  Brooks  was
employed by Merck & Co., Inc. for 27 years, most recently, from 1986 to 1993, as
Senior Counsel. From 1980 to 1985, Mr. Brooks served as a U.S. employer delegate
to the Chemical Industries Committee International Labor Organization in Geneva,
Switzerland.
 
    BART  CHERNOW, M.D. is a  co-founder of the Company  and has been a director
since the Company's inception. Dr.  Chernow has served as Physician-in-Chief  at
Sinai  Hospital  of  Baltimore  since  1990  and  as  a  Professor  of Medicine,
Anesthesiology and  Critical Care  at  The Johns  Hopkins University  School  of
Medicine part-time since 1990. Dr. Chernow is the Editor-in-Chief of the Journal
of CRITICAL CARE MEDICINE. From 1987 to 1990 Dr. Chernow was the Director of the
Henry  K.  Beecher Memorial  Research  Laboratories and  Attending  Physician of
Critical Care  (anesthesia)  at  the  Massachusetts  General  Hospital,  Harvard
Medical School, where he also served as an Associate Professor.
 
    SAMUEL  R. DUNLAP, JR. has served as  an Executive Advisor and a director to
the Company since August  1992. Mr. Dunlap  also has (i)  served as Chairman  of
Dunlap  & Partners, Ltd., a financial consulting firm in Atlanta, Georgia, since
October 1988, (ii) served as an Executive Advisor and is currently a director to
First Pacific Networks, Inc., a publicly-held telecommunications company,  (iii)
served  as a director  of Credit Depot  Corporation, of which  he was a founder,
since December 1986, (iv) served as a director and a consultant of Golf Training
Systems, Inc., a public  company, from August 1994  until December 1995 and  (v)
served as a director from July 1991 until February 1994 and an Executive Advisor
from  July 1991 until November 1994  of Tapistron International, Inc. From April
1986 until December  1988, Mr.  Dunlap served  as Executive  Vice President  and
director  of CytRx Corporation, a publicly-held pharmaceutical company ("CytRx")
of which he was a founder. Mr. Dunlap also served as Executive Vice President of
Elan Pharmaceutical Research Corp., a publicly-held company, from August 1982 to
December 1983 and President and a director  of such entity from January 1984  to
January 1985.
 
                                       36
<PAGE>
    MARK C.M. RANDALL has been a director of the Company since April 1996. Since
1985,  Mr.  Randall has  been associated  with Sarasin  International Securities
Limited, London, England,  a wholly-owned subsidiary  of Bank Sarasin  & Cie,  a
private bank based in Switzerland, where he has been Director since 1994.
 
    LEON  E. ROSENBERG, M.D.  has been a  director of the  Company since January
1996. Since  September  1991  Dr.  Rosenberg has  served  as  the  President  of
Bristol-Myers  Squibb Pharmaceutical Research Institute.  From 1984 to September
1991, Dr.  Rosenberg  served  as the  dean  of  the Yale  University  School  of
Medicine.  Dr. Rosenberg  is a  member of the  National Academy  of Sciences and
serves on  the Board  of Directors  of the  Whitehead Institute  for  Biomedical
Research.
 
    WENDELL  M. STARKE has been a director  of the Company since April 1994. Mr.
Starke is a Chartered  Financial Analyst and  a Chartered Investment  Counselor.
Mr.  Starke was President of INVESCO Capital  Management, Inc. from 1979 to 1991
and has been its Chairman  since 1991. In 1992,  he became Chairman of  INVESCO,
Inc.,  the parent company of INVESCO  Capital Management and other INVESCO money
management subsidiaries  with 1995  year-end assets  of over  $75 billion  under
management  in the  United States.  Mr. Starke  also serves  as a  member of the
Board, Global  Chief  Investment  Officer  and  Chairman  of  the  Global  Asset
Allocation  Committee of  INVESCO, PLC, the  London-based parent  company of the
worldwide INVESCO organization.
 
    The Board of Directors  currently consists of  eight members. Successors  to
those  directors  whose  terms  have  expired  are  required  to  be  elected by
stockholder vote;  vacancies in  unexpired terms  and any  additional  positions
created by board action are filled by action of the existing Board of Directors.
Officers  are  elected to  serve,  subject to  the  discretion of  the  Board of
Directors, until their successors are appointed.
 
    The Executive Committee currently consists  of three members. The  Executive
Committee acts as a liaison between management and the Board of Directors and is
responsible  for all matters that arise between regular meetings of the Board of
Directors, to the extent permitted by Delaware law.
 
    The Audit Committee currently consists of two directors. The Audit Committee
reviews, with the  Company's independent  accountants, the scope  and timing  of
their  audit services and  any other services  they are asked  to perform, their
report on the Company's financial statements following completion of their audit
and the Company's policies  and procedures with  respect to internal  accounting
and   financial  controls.  In  addition,   the  Audit  Committee  makes  annual
recommendations to the  Board of  Directors for the  appointment of  independent
public accountants for the ensuing year.
 
    The  Compensation  Committee  consists of  three  directors.  This Committee
reviews and recommends to the Board  of Directors the compensation and  benefits
of  all  officers of  the Company,  reviews general  policy matters  relating to
compensation and  benefits  of employees  of  the Company  and  administers  the
Company's stock option plans.
 
                                       37
<PAGE>
EXECUTIVE COMPENSATION
 
    The   following  summary   compensation  table  sets   forth  the  aggregate
compensation paid or accrued by the  Company to the Chief Executive Officer  and
to  each  of  the  most  highly  compensated  executive  officers  whose  annual
compensation exceeded  $100,000 for  the  fiscal year  ended December  31,  1995
(collectively,  the "named executive  officers") for services  during the fiscal
year ended December 31, 1995:
 
                           SUMMARY COMPENSATION TABLE
 
   
<TABLE>
<CAPTION>
                                                                          LONG TERM
                                             ANNUAL COMPENSATION        COMPENSATION
                                       -------------------------------     AWARDS          ALL OTHER
NAME AND PRINCIPAL POSITION            ANNUAL SALARY($)    BONUS ($)    OPTIONS (NO.)  COMPENSATION ($)
- -------------------------------------  ----------------  -------------  -------------  -----------------
<S>                                    <C>               <C>            <C>            <C>
John W. Holaday, Ph.D. ..............        200,000        100,000          270,001          12,551(1)
 Chairman, President and Chief
 Executive Officer
Carol A. Nacy, Ph. D. ...............        175,000         60,750          166,667          --
 Executive Vice President
Edward R. Gubish, Ph.D. .............        126,600         10,750(2)        70,000          --
 Vice President -- Regulatory and
 Clinical Development
Leo Einck, Ph.D. ....................         91,000         10,750(2)        70,000          --
 Vice President -- Extramural
 Programs
</TABLE>
    
 
- ------------------------
   
(1) Represents the premiums paid by the  Company with respect to a  split-dollar
    life  insurance policy  on the  life of  Dr. Holaday.  Premiums paid  by the
    Company on such policy are treated  as non-interest bearing advances to  the
    insured  for  the policy.  The  initial proceeds  of  any death  benefit are
    required to  be used  to repay  the  indebtedness, and  the balance  of  the
    insurance  proceeds  are  payable  as designated  by  the  insured.  See "--
    Employment Agreements."
    
 
   
(2) Includes $10,000 accrued in 1995 and paid in 1996.
    
 
    The  following  table  sets  forth  certain  information  with  respect   to
individual  grants of  stock options  and warrants  made during  the fiscal year
ended December 31, 1995 to each of the named executive officers.
 
                 OPTION AND WARRANT GRANTS IN LAST FISCAL YEAR
 
   
<TABLE>
<CAPTION>
                                                             INDIVIDUAL GRANTS                       POTENTIAL REALIZABLE
                                           ------------------------------------------------------  VALUE AT ASSUMED ANNUAL
                                                          % OF TOTAL                                 RATES OF STOCK PRICE
                                                         OPTIONS/SARS                              APPRECIATION FOR OPTION
                                            OPTIONS/      GRANTED TO      EXERCISE                         TERM (1)
                                              SARS         EMPLOYEES       OR BASE    EXPIRATION   ------------------------
NAME                                       GRANTED (#)  IN FISCAL YEAR   PRICE ($/SH)    DATE        5% ($)       10% ($)
- -----------------------------------------  -----------  ---------------  -----------  -----------  -----------  -----------
<S>                                        <C>          <C>              <C>          <C>          <C>          <C>
John W. Holaday, Ph.D. ..................     270,001          22.6%      $   6.444     11/1/2005    4,875,678    8,783,403
Carol A. Nacy, Ph.D. ....................     166,667          13.9%      $   6.330     11/1/2005    3,009,673    5,421,844
Edward R. Gubish, Ph.D. .................      70,000           5.8%      $   6.375     11/1/2005    1,264,060    2,277,170
Leo Einck, Ph.D. ........................      70,000           5.8%      $   6.375     11/1/2005    1,264,060    2,277,170
</TABLE>
    
 
- ------------------------
(1) Assumes an initial public offering price  of $15.00. The 5% and 10%  assumed
    annual  rates of appreciation  are mandated by the  rules and regulations of
    the Securities  and Exchange  Commission and  do not  reflect the  Company's
    estimates  or projections  of future  Common Stock  prices. There  can be no
    assurance that the rates of return reflected in the table will be achieved.
 
                                       38
<PAGE>
    The following table  sets forth information  concerning all option  holdings
for  the fiscal  year ended December  31, 1995  for each of  the named executive
officers:
 
                AGGREGATED OPTION/EXERCISES IN LAST FISCAL YEAR
                            AND FY-END OPTION/VALUE
 
<TABLE>
<CAPTION>
                                                                           NUMBER OF
                                                                      UNEXERCISED OPTIONS  VALUE OF UNEXERCISED IN-THE-
                                                                         AT FY-END (#)         MONEY OPTIONS AT FY-
                                        SHARES ACQUIRED     VALUE        EXERCISABLE/               END ($)(1)
NAME                                    ON EXERCISE (#)  REALIZED ($)    UNEXERCISABLE      EXERCISABLE/UNEXERCISABLE
- --------------------------------------  ---------------  -----------  -------------------  ----------------------------
<S>                                     <C>              <C>          <C>                  <C>
John W. Holaday, Ph.D. ...............        --             --         176,669/200,000    $   1,993,767/$1,725,000
Carol A. Nacy, Ph.D. .................        --             --         170,000/146,667    $   2,205,000/$1,265,003
Edward R. Gubish, Ph.D. ..............        --             --          30,000/80,000     $     270,000/$693,750
Leo Einck, Ph.D. .....................        --             --          10,667/72,667     $     96,003/$627,753
</TABLE>
 
- ------------------------
(1) Assumes that  the fair  market  of the  common  stock equalled  the  assumed
    initial public offering price of $15.00.
 
EMPLOYMENT AGREEMENTS
 
    In  April 1996, effective as of January  1, 1996, the Company entered into a
three-year employment agreement with John W. Holaday, Ph.D., Chairman and  Chief
Executive  Officer of  the Company.  The agreement  provides for  an annual base
salary of $250,000  per year. The  Company may terminate  the agreement  without
cause  and, upon such termination,  Dr. Holaday will be  entitled to receive his
base salary through the end of the initial term of the agreement (subject to  an
offset  for salary received from  subsequent employment). The agreement contains
confidentiality and non-competition provisions.
 
   
    The Company is  the beneficiary of  a $1,000,000 key  person life  insurance
policy  on  the  life of  Dr.  Holaday.  In addition,  the  Company  maintains a
$2,000,000 split-dollar life insurance policy on  the life of Dr. Holaday at  an
annual  cost  of approximately  $12,500. Premiums  paid by  the Company  on such
policy are  treated as  non-interest bearing  advances to  the insured  for  the
policy.  The initial proceeds  of any death  benefit are required  to be used to
repay the indebtedness, and the balance of the insurance proceeds are payable as
designated by the insured.
    
 
    Each of the Company's employees  has entered into a Proprietary  Information
and  Invention  Assignment Agreement  providing, among  other things,  that such
employee will not disclose any confidential information or trade secrets in  any
unauthorized  manner and  that all  inventions of  such officer  relating to the
Company's current or anticipated business  during the term of employment  become
the Company's property.
 
DIRECTOR COMPENSATION
 
    Directors are entitled to compensation of $2,000 for each Board of Directors
meeting attended and are reimbursed for expenses actually incurred in connection
with  attending  such meetings.  Directors are  also  awarded initial  grants of
non-qualified stock  options to  purchase  15,000 shares  of Common  Stock  upon
joining  the Board of Directors and annual grants of non-qualified stock options
to purchase  5,000  shares  of Common  Stock.  In  addition, each  member  of  a
committee  of the Board  of Directors will receive  certain additional grants of
non-qualified stock options.  All options are  granted at the  then fair  market
value. See "-- Stock Options" and "Certain Transactions."
 
LIMITATION ON LIABILITY; INDEMNIFICATION AGREEMENTS
 
    The  General Corporation Law  of Delaware permits  a corporation through its
Certificate  of  Incorporation  to  eliminate  the  personal  liability  of  its
directors to the corporation or its stockholders for monetary damages for breach
of   fiduciary  duty   of  loyalty  and   care  as  a   director,  with  certain
 
                                       39
<PAGE>
exceptions. The exceptions include a breach  of the director's duty of  loyalty,
acts  or omissions not in good faith  or which involve intentional misconduct or
knowing violation of law, improper  declarations of dividends, and  transactions
from  which the  directors derived an  improper personal  benefit. The Company's
Certificate of Incorporation exonerates its directors from monetary liability to
the fullest extent permitted by this  statutory provision but does not  restrict
the availability of non-monetary and other equitable relief.
 
    The  Company intends to  enter into Indemnification  Agreements with each of
its directors and executive officers.  Each such Indemnification Agreement  will
provide  that  the  Company  will  indemnify  the  indemnitee  against expenses,
including reasonable attorney's  fees, judgments, penalties,  fines and  amounts
paid  in settlement actually  and reasonably incurred by  him in connection with
any civil or  criminal action or  administrative proceeding arising  out of  the
performance  of his  duties as  an officer, director,  employee or  agent of the
Company. Such indemnification is available if the acts of the indemnitee were in
good faith, if the indemnitee acted in a manner he reasonably believed to be  in
or  not opposed to  the best interests of  the Company and,  with respect to any
criminal proceeding,  the indemnitee  had  no reasonable  cause to  believe  his
conduct was unlawful.
 
STOCK OPTIONS
 
   
    GENERAL.   In  December 1992, the  Company adopted the  1992 Stock Incentive
Plan (the "1992 Plan"), which provides for  the grant by the Company of  options
to  purchase up to an aggregate of  1,233,333 shares of the Company's authorized
but unissued Common Stock and in March 1996, the Company adopted the 1996  Stock
Option  Plan, which was amended and restated in April 1996 (the "1996 Plan" and,
together with the 1992 Plan,  the "Plans"), which provide  for the grant by  the
Company  of options  to purchase  up to  an aggregate  of 516,667  shares of the
Company's authorized  but  unissued  Common  Stock  (in  each  case  subject  to
adjustment  in  certain  cases  including  stock  splits,  recapitalizations and
reorganizations) to officers, directors, employees, consultants and  independent
contractors  of  the  Company. The  purposes  of  the Plans  are  to  ensure the
retention  of  existing  executive  personnel,  key  employees,  directors   and
consultants  of  the  Company, to  attract  and retain  competent  new executive
personnel, key employees,  directors and consultants  and to provide  additional
incentive to all such persons by permitting them to participate in the ownership
of  the Company.  The 1992 Plan  terminates in  December 2002 and  the 1996 Plan
terminates in March 2006.
    
 
    The Plans will be administered by the  Board of Directors or a committee  of
the  Board of Directors, provided, however,  that with respect to "officers" and
"directors," as such  terms are defined  for the purposes  of Rule 16b-3  ("Rule
16b-3")  promulgated under  the Securities Exchange  Act of  1934 (the "Exchange
Act"), such committee shall consist  of "disinterested" directors as defined  in
Rule   16b-3,  but  only  if  at  least  two  directors  meet  the  criteria  of
"disinterested" directors as defined in Rule  16b-3. The 1996 Plan provides  for
automatic  grants of options to certain directors  in the manner set forth below
under "Directors' Options."
 
    Options  granted  under  the  Plans  may  be  either  incentive  options  or
non-qualified options. Incentive options granted under the Plans are exercisable
for a period of up to 10 years from the date of grant at an exercise price which
is  not less than the fair  market value of the Common  Stock on the date of the
grant, except that the term of an incentive option granted under the Plans to  a
stockholder  owning more than 10% of the outstanding voting power may not exceed
five years and its exercise price may not  be less than 110% of the fair  market
value  of the  Common Stock on  the date  of the grant.  To the  extent that the
aggregate fair market value, as  of the date of grant,  of the shares for  which
incentive  options become exercisable  for the first time  by an optionee during
the calendar  year exceeds  $100,000, the  portion of  such option  which is  in
excess  of the  $100,000 limitation will  be treated as  a non-qualified option.
Additionally, the aggregate number of shares of Common Stock that may be subject
to options granted to any person in a calendar year shall not exceed 25% of  the
maximum  number of shares of Common Stock which  may be issued from time to time
under the Plans. Options
 
                                       40
<PAGE>
granted under the Plans to officers,  directors or employees of the Company  may
be  exercised only while the optionee is  employed or retained by the Company or
within 90 days  of the  date of termination  of the  employment relationship  or
directorship.  However, options which are exercisable at the time of termination
by reason of  death or  permanent disability of  the optionee  may be  exercised
within  12 months of the  date of termination of  the employment relationship or
directorship. Upon the exercise of an option, payment may be made by cash or  by
any other means that the Board of Directors or the committee determines.
 
    Options  may be granted  only to such employees,  officers and directors of,
and consultants and advisors to, the Company or any subsidiary of the Company as
the Board of Directors or  the committee shall select from  time to time in  its
sole  discretion, provided that only employees of the Company or a subsidiary of
the Company shall  be eligible  to receive incentive  options. As  of March  31,
1996, the number of employees, officers and directors of the Company eligible to
receive  grants  under the  Plans was  approximately 35  persons. The  number of
consultants and advisors  to the Company  eligible to receive  grants under  the
Plans is not determinable. An optionee may be granted more than one option under
the  Plans. The  Board of  Directors or the  committee will,  in its discretion,
determine (subject to the terms of the  Plans) who will be granted options,  the
time or times at which options shall be granted, the number of shares subject to
each  option  and whether  the options  are  incentive options  or non-qualified
options. In making such determination, consideration  may be given to the  value
of  the  services  rendered by  the  respective individuals,  their  present and
potential contributions to the success of  the Company and its subsidiaries  and
such other factors deemed relevant in accomplishing the purpose of the Plans.
 
    Under  the Plans, the optionee has none  of the rights of a stockholder with
respect to the shares issuable upon the exercise of the option until such shares
shall be issued upon such exercise. No adjustment shall be made for dividends or
distributions or other rights for which the record date is prior to the date  of
exercise,  except as provided in the Plans. During the lifetime of the optionee,
an option shall  be exercisable only  by the  optionee. No option  may be  sold,
pledged,  assigned, hypothecated, transferred or disposed of in any manner other
than by will or by the laws of decent and distribution.
 
    The Board  of  Directors  may  amend or  terminate  the  Plans  except  that
stockholder  approval  is required  to effect  a  change so  as to  increase the
aggregate number of shares that may  be issued under the Plans (unless  adjusted
to  reflect  such  changes  as  a  result  of  a  stock  dividend,  stock split,
recapitalization, merger  or  consolidation  of  the  Company),  to  modify  the
requirements  as to eligibility  to receive options,  to increase materially the
benefits accruing to participants or as otherwise may be required by Rule  16b-3
or  Section 422  of the Code.  No action taken  by the Board  may materially and
adversely affect  any  outstanding  option  grant without  the  consent  of  the
optionee.
 
    Under  current  tax law,  there are  no Federal  income tax  consequences to
either the employee  or the  Company on the  grant of  non-qualified options  if
granted under the terms set forth in the Plans. Upon exercise of a non-qualified
option,  the excess of the fair market value of the shares subject to the option
over the option  price (the  "Spread") at  the date  of exercise  is taxable  as
ordinary income to the optionee in the year it is exercised and is deductible by
the  Company as compensation for Federal  income tax purposes, if Federal income
tax is withheld on  the Spread. However,  if the shares  are subject to  vesting
restrictions  conditioned on future  employment or the holder  is subject to the
short-swing profits liability restrictions of Section 16(b) of the Exchange  Act
of  (i.e., is an executive officer, director  or 10% stockholder of the Company)
then taxation and measurement of the Spread is deferred until such  restrictions
lapse,  unless a  special election is  made under  Section 83(b) of  the Code to
report such income currently without regard to such restrictions. The optionee's
basis in the shares will be equal to the fair market value on the date  taxation
is imposed and the holding period commences on such date.
 
                                       41
<PAGE>
    Incentive  option holders incur  no regular Federal  income tax liability at
the time of grant or  upon exercise of such  option, assuming that the  optionee
was  an employee of  the Company from the  date the option  was granted until 90
days before such exercise. However, upon  exercise, the Spread must be added  to
regular  Federal taxable income in computing the optionee's "alternative minimum
tax" liability. An  optionee's basis in  the shares received  on exercise of  an
incentive  stock option  will be  the option  price of  such shares  for regular
income tax purposes. No deduction is allowable to the Company for Federal income
tax purposes in connection with the grant or exercise of such option.
 
    If the holder  of shares acquired  through exercise of  an incentive  option
sells such shares within two years of the date of grant of such option or within
one   year  from  the  date  of   exercise  of  such  option  (a  "Disqualifying
Disposition"), the  optionee  will realize  income  taxable at  ordinary  rates.
Ordinary  income  is  reportable during  the  year  of such  sale  equal  to the
difference between the option price and the  fair market value of the shares  at
the  date the option is exercised, but  the amount includable as ordinary income
shall not exceed  the excess,  if any,  of the proceeds  of such  sale over  the
option  price. In addition  to ordinary income,  a Disqualifying Disposition may
result in  taxable  income subject  to  capital  gains treatment  if  the  sales
proceeds  exceed the optionee's basis in the shares (i.e., the option price plus
the amount includable as ordinary income). The amount of the optionee's  taxable
ordinary  income  will  be  deductible  by  the  Company  in  the  year  of  the
Disqualifying Disposition.
 
    At the time of  sale of shares  received upon exercise  of an option  (other
than  a Disqualifying  Disposition of  shares received  upon the  exercise of an
incentive option), any gain or loss  is long-term or short-term capital gain  or
loss,  depending  upon  the holding  period.  The holding  period  for long-term
capital gain or loss treatment is more than one year.
 
    The foregoing  is not  intended to  be  an exhaustive  analysis of  the  tax
consequences relating to stock options issued under the Plans. For instance, the
treatment  of options  under state  and local tax  laws, which  is not described
above, may differ from the treatment for Federal income tax purposes.
 
    As of March 31, 1996, there were outstanding under the 1992 Plan options  to
purchase  1,107,031 shares of Common Stock at exercise prices ranging from $1.50
to $15.00 per  share and no  options were  outstanding under the  1996 Plan.  In
addition,  the Company had outstanding at March 31, 1996 133,334 options granted
outside of the Plans at exercise prices ranging from $6.00 to $6.375 per  share.
The exercise price of all options was at least equal to the fair market value on
the date of grant.
 
   
    DIRECTORS'  OPTIONS.    The provisions  of  the  1996 Plan  provide  for the
automatic grant  of non-qualified  stock options  to purchase  shares of  Common
Stock  ("Director Options") to directors  of the Company ("Eligible Directors").
Eligible Directors of the Company elected after the date hereof will be  granted
a  Director Option to  purchase 15,000 shares  of Common Stock  on the date such
person is first elected or appointed a director (an "Initial Director  Option").
Further,  commencing on  the day  immediately following  the date  of the annual
meeting of stockholders for the Company's fiscal year ending December 31,  1996,
(i)  each Eligible Director will be granted  a Director Option to purchase 5,000
shares of  Common  Stock,  (ii) each  member  of  the Audit  Committee  and  the
Compensation  Committee  will be  granted a  Director  Option to  purchase 1,000
shares of Common Stock and (iii) each member of the Executive Committee will  be
granted  a Director Option  to purchase 5,000  shares of Common  Stock (each, an
"Automatic Grant") on  the day  immediately following  the date  of each  annual
meeting  of stockholders, as long  as such director is a  member of the Board of
Directors or such committee,  as the case  may be. The  exercise price for  each
share  subject to a Director  Option shall be equal to  the fair market value of
the Common  Stock  on  the date  of  grant,  except for  directors  who  receive
incentive  options and who own more than 10%  of the voting power, in which case
the exercise price shall be not less than  110% of the fair market value on  the
date   of  grant.  Director  Options  are  exercisable  in  three  equal  annual
installments, commencing on the date of grant. Director Options will expire  the
earlier  of 10 years after the date of grant or 90 days after the termination of
the director's service on the Board of Directors.
    
 
                                       42
<PAGE>
COMPENSATION COMMITTEE INTERLOCKS AND INSIDER PARTICIPATION
 
    The Board  of  Directors  of  the Company  has  established  a  Compensation
Committee which, during fiscal 1995, consisted of Samuel R. Dunlap, Jr., Wendell
M. Starke and Bart Chernow, M.D.
 
    In  November  1995, the  Company issued  to Mr.  Dunlap options  to purchase
166,667 shares of Common  Stock at an  exercise price of  $6.375 per share.  The
Company  has in the past maintained a consulting arrangement with Mr. Dunlap and
in January 1996  entered into  a new three  year consulting  agreement with  Mr.
Dunlap  that  provides for  annual payments  of $90,000.  In November  1995, the
Company granted  Mr. Dunlap  warrants to  purchase 166,667  shares,  exercisable
66,667  immediately and the  remainder in three equal  annual installments at an
exercise price of $6.375 per share.
 
   
    In April  1993, a  trust  of which  Wendell M.  Starke  is the  trustee  and
beneficiary  (the "Starke Trust")  purchased 50,000 shares  of Common Stock from
the Company at a  purchase price of  $6.00 per share. In  July 1994, the  Starke
Trust  loaned the  Company $300,000, which  loan was evidenced  by a convertible
promissory note payable on demand bearing interest at 8% per annum. In September
1994, the principal  amount of  such note was  converted into  47,066 shares  of
Common  Stock (a  conversion price  of $6.375 per  share). In  October 1994, the
Starke Trust  purchased 84,633  shares of  Common Stock  from the  Company at  a
purchase price of $6.375 per share. In February 1995, the Starke Trust purchased
33,333 shares of Common Stock from the Company at a purchase price of $6.375 per
share.  In June 1995, Mr. Starke loaned  the Company an aggregate of $162,916 in
exchange for a  promissory note  due and paid  in December  1995, together  with
interest  at the rate of 9% per annum, and warrants to purchase 10,648 shares at
$6.375 per share. See "Certain Transactions."
    
 
                              CERTAIN TRANSACTIONS
 
    In October 1991, the Company issued  333,333 shares of Common Stock to  each
of  Steve Gorlin, John W. Holaday, Ph.D.  and Bart Chernow, M.D., co-founders of
the Company, at a purchase price of $.015 per share.
 
    In June 1992, the Company issued an aggregate of 1,545,000 shares of  Common
Stock  at a purchase price of $.015  per share, including 433,333 shares to each
of Drs. Holaday and Chernow, 133,333 shares to Mark Rogers, M.D., 50,000  shares
to  Steve Gorlin and 33,333  shares to each of  Stephen Ayres, M.D., David Evans
and Richard Franco. Each of Messrs. Rogers, Gorlin, Ayres, Evans and Franco  was
a  director of the Company at the time  of the transaction. In addition, in June
1992, the Company  sold 1,500,000  shares of Preferred  Stock to  each of  Steve
Gorlin  and to D.H. Blair Investment Banking  Corp. at a purchase price of $1.00
per share. Mr. Gorlin  paid for a  portion of his shares  of Preferred Stock  by
executing  a promissory note in  the principal amount of  $350,000. The note was
payable with interest at  8% per annum  and was paid in  full in December  1993,
partially  through the  offset of  $220,000 of amounts  due Mr.  Gorlin from the
Company for use of his aircraft for Company business, as noted below.
 
    In June 1992, the  Company and Carl  Alving, M.D. entered  into a Stock  and
Asset  Exchange Agreement pursuant  to which Dr. Alving  assigned to the Company
his rights  to  various vaccine  technologies.  In return,  the  Company  issued
766,666 shares of Common Stock to Dr. Alving, paid Dr. Alving an initial royalty
of  $40,000 and agreed to pay annual royalties of $40,000 through June 1996. See
"Management -- Director Compensation."
 
    From the inception  of the Company  through December 31,  1993, the  Company
utilized  aircraft owned by Steve Gorlin  or entities controlled by Steve Gorlin
at a  cost  of  approximately  $220,000, which  amount  was  determined  by  the
Company's  Board of Directors to be the fair market value based on costs charged
by other chartered  service operators.  Such amounts  were paid  by the  Company
through  offset against the $350,000 note payable by Mr. Gorlin described above.
In May 1992, the
 
                                       43
<PAGE>
Company extended an interest-free loan  of approximately $24,000 to Mr.  Gorlin,
which amount was repaid in August 1992. From inception until August 1, 1992, the
Company operated out of the offices of Mr. Gorlin at no cost to the Company.
 
   
    In April 1993, the Starke Trust purchased 50,000 shares of Common Stock from
the  Company at a  purchase price of $6.00  per share. In  July 1994, the Starke
Trust loaned the  Company $300,000, which  loan was evidenced  by a  convertible
promissory note payable on demand bearing interest at 8% per annum. In September
1994,  the principal  amount of  such note was  converted into  47,066 shares of
Common Stock (a  conversion price  of $6.375 per  share). In  October 1994,  the
Starke  Trust purchased  84,633 shares  of Common  Stock from  the Company  at a
purchase price of $6.375 per share. In February 1995, the Starke Trust purchased
33,333 shares of Common Stock from the Company at a purchase price of $6.375 per
share. In June 1995, Mr. Starke loaned  the Company an aggregate of $162,916  in
exchange  for a  promissory note  due and paid  in December  1995, together with
interest at the rate of 9% per annum, and warrants to purchase 10,648 shares  at
$6.375  per share. In November 1995, the  Company granted Mr. Dunlap warrants to
purchase 166,667 shares,  exercisable 66,667  immediately and  the remainder  in
three equal annual installments at an exercise price of $6.375 per share.
    
 
    The Company and Mr. Gorlin, Dr. Holaday, Dr. Alving, Dr. Chernow, D.H. Blair
Investment  Banking  Corp.  and  Kinder  Investments,  L.P.  are  parties  to  a
Shareholder Agreement, dated June 4, 1992,  as amended and restated on  December
10,  1993 (the "Shareholder Agreement"). The Shareholder Agreement grants to Dr.
Alving the right, in connection with an initial public offering of the Company's
securities, to request the  registration of shares of  Common Stock held by  him
having  a value of $250,000. Mr. Gorlin  agreed to purchase such shares from Dr.
Alving in the event that such shares  are not so registered following a  request
by Dr. Alving. Dr. Alving has waived his right to request such registration.
 
   
    Pursuant  to a consulting  arrangement, the Company paid  Mr. Dunlap fees of
$54,000 in each of 1993, 1994 and 1995 and a $100,000 bonus in 1995. The Company
entered into  a  three year  consulting  agreement with  Mr.  Dunlap  commencing
January 1, 1996 that provides for annual payments of $90,000. See "Management --
Director  Compensation." In May 1996 effective  August 1995, the Company entered
into a termination agreement with Steve Gorlin, a co-founder and former director
of the Company,  superseding a  previous consulting agreement  with Mr.  Gorlin,
that provides for annual payments of $90,000 per year for a three year period.
    
 
                                       44
<PAGE>
                             PRINCIPAL STOCKHOLDERS
 
   
    The  following table sets forth  certain information regarding the ownership
of Common Stock for  (i) each person  known by the  Company to own  beneficially
more  than five percent of the outstanding  voting stock, (ii) each director and
named executive officer  of the  Company and  (iii) all  executive officers  and
directors  of the Company as a group, prior  to this offering and as adjusted to
give effect to the sale of the Common  Stock offered hereby and the sale of  the
BMS Shares.
    
 
   
<TABLE>
<CAPTION>
                                                                                             SHARES TO BE
                                                                                             PURCHASED IN
                                                  NUMBER OF SHARES         PERCENTAGE         CONCURRENT         PERCENTAGE
NAME AND ADDRESS OF                              BENEFICIALLY OWNED       OWNED BEFORE          PRIVATE         OWNED AFTER
BENEFICIAL OWNER (1)                               BEFORE OFFERING          OFFERING           PLACEMENT          OFFERING
- -----------------------------------------------  -------------------      -------------      -------------      ------------
<S>                                              <C>                      <C>                <C>                <C>
John W. Holaday, Ph.D..........................             886,901(2)              10.27%                                7.29%
Carl R. Alving, M.D............................             778,235(3)               9.19                                 6.48
Donald S. Brooks...............................              40,001(4)         *                                     *
Bart Chernow, M.D..............................             714,917(3)               8.44                                 5.96
Samuel R. Dunlap, Jr...........................             394,237(5)               4.50                                 3.21
Leo Einck, Ph.D................................              11,667(6)         *                                     *
Edward R. Gubish, Ph.D.........................              31,000(7)         *                                     *
Carol A. Nacy, Ph.D............................             170,000(8)               1.97                                 1.40
Mark C.M. Randall..............................              40,001(4)         *                                     *
Leon E. Rosenberg, M.D.........................                  --(9)         --                                   --
Wendell M. Starke..............................             318,097(10)              3.72                                 2.63
Bristol-Myers Squibb Company ..................             986,110(11)             11.07         333,333(12)            10.61
 P.O. Box 4000
 Princeton, New Jersey 08543
D.H. Blair Investment Banking Corp. .                     1,000,000(13)             11.82                                 8.36
 44 Wall Street
 New York, New York 10005
Steve Gorlin...................................             706,709(14)              8.25                                 5.84
All executive officers and directors of the
 Company as a group (12 persons)...............           3,405,223(15)             37.12                                26.24
</TABLE>
    
 
- ------------------------
  * Less than 1%
 
 (1)Unless  otherwise indicated, the address is c/o EntreMed, Inc., 9610 Medical
    Center Drive, Suite 200, Rockville, MD 20850. Except as otherwise indicated,
    each of the parties listed above  has sole voting and investment power  over
    the shares owned.
 
 (2)Includes  176,669  shares  issuable  upon  exercise  of  options  which  are
    currently  exercisable.  Does  not  include  200,000  shares  issuable  upon
    exercise of options not exercisable within 60 days.
 
 (3)Includes 10,002 shares issuable upon exercise of options which are currently
    exercisable.
 
 (4)Includes 40,001 shares issuable upon exercise of options which are currently
    exercisable.
 
 (5)Includes  293,336  shares  issuable  upon  exercise  of  options  which  are
    currently  exercisable.  Does  not  include  100,000  shares  issuable  upon
    exercise of options not exercisable within 60 days.
 
 (6)Includes 10,667 shares issuable upon exercise of options which are currently
    exercisable.  Does  not  include  72,667 shares  issuable  upon  exercise of
    options not exercisable within 60 days.
 
                                       45
<PAGE>
 (7)Includes 30,000 shares issuable upon exercise of options which are currently
    exercisable. Does  not  include  80,000 shares  issuable  upon  exercise  of
    options not exercisable within 60 days.
 
 (8)Includes  170,000  shares  issuable  upon  exercise  of  options  which  are
    currently  exercisable.  Does  not  include  146,667  shares  issuable  upon
    exercise of options not exercisable within 60 days.
 
 (9)Does not include shares owned by Bristol-Myers Squibb Company. Dr. Rosenberg
    is  the President of Bristol-Myers Squibb Pharmaceutical Research Institute,
    an  entity  affiliated  with  Bristol-Myers,  and  he  disclaims  beneficial
    ownership of any shares held by Bristol-Myers.
 
   
(10)Includes  (i) 83,984 shares  issuable upon exercise  of options and warrants
    which are  currently exercisable  and (ii)  40,561 shares  owned by  various
    family  members of Mr.  Starke, as to which  Mr. Starke disclaims beneficial
    ownership.
    
 
(11)Includes 444,444 shares (assuming an initial public offering price of $15.00
    per share) issuable upon exercise of warrants which are exercisable for  one
    year commencing on the date of this Prospectus.
 
(12)Represents  shares which Bristol-Myers has agreed to purchase on the date of
    this Prospectus.
 
   
(13)Excludes (i) 375,666 shares owned by the adult children and grandchildren of
    J. Morton Davis, the sole stockholder of D.H. Blair Investment Banking Corp.
    ("Blair") and (ii) 18,000 shares owned by the Vice Chairman of Blair and his
    children, as to all  of which shares  Blair disclaims beneficial  ownership.
     Also  excludes an aggregate  of 1,061,563 shares owned  by Steve Gorlin and
    June Gorlin,  Mr. Gorlin's  former wife,  which are  subject to  the  Gorlin
    Pledge (as defined below).
    
 
   
(14)Includes  (i) 110,002  shares issuable  upon exercise  of options  which are
    currently exercisable and (ii) 15,134 shares owned by Mr. Gorlin's children,
    as to which  Mr. Gorlin disclaims  beneficial ownership. All  of the  shares
    owned  by Mr.  Gorlin are  pledged to  Blair and  J. Morton  Davis to secure
    obligations owed by Mr. Gorlin to  Blair (the "Gorlin Pledge"). Such  shares
    may  be voted by  Mr. Gorlin until such  time as a  default occurs under the
    Gorlin Pledge or the underlying obligation. Does not include 381,192  shares
    owned by June Gorlin, as to which Mr. Gorlin disclaims beneficial ownership.
    Includes  30,000  shares that  Mr. Gorlin  has agreed  to distribute  to his
    former wife. See footnote 13 above.
    
 
(15)Includes  982,997  shares  issuable  upon  exercise  of  options  which  are
    currently  exercisable.  Does  not  include  599,334  shares  issuable  upon
    exercise of options not exercisable within 60 days.
 
    Each of Steve Gorlin and  Drs. Holaday, Alving and  Chernow may be deemed  a
"founder" of the Company, as that term is defined under the Securities Act.
 
                                       46
<PAGE>
                          DESCRIPTION OF CAPITAL STOCK
 
    Set  forth below  is a  summary of  the terms  of the  capital stock  of the
Company. Such summary is qualified in its entirety by reference to the Company's
Restated Certificate of Incorporation, attached as an exhibit hereto, and  gives
effect to the filing of a Certificate of Amendment thereto, the form of which is
attached as an exhibit hereto.
 
    The  Company's  authorized capital  stock  currently consists  of 27,000,000
shares of Common Stock, $.01 par value, and 8,000,000 shares of Preferred Stock,
$1.00 par value.
 
COMMON STOCK
 
   
    Immediately prior to the date hereof, there were 8,460,579 shares of  Common
Stock  outstanding (including 2,000,000  shares issuable upon  conversion of the
3,000,000 outstanding  shares  of Preferred  Stock)  held by  approximately  260
shareholders  of record. Holders of  shares of Common Stock  are entitled to one
vote at all meetings  of shareholders for  each share held by  them and are  not
entitled to cumulative voting. Holders of Common Stock have no preemptive rights
and  have no other rights to subscribe  for additional shares of the Company nor
does the Common Stock have any conversion rights or rights of redemption, either
of which rights have not  been waived. Holders of  Common Stock are entitled  to
receive  ratably such dividends as may be declared by the Board of Directors out
of funds legally  available therefor. See  "Dividend Policy." Upon  liquidation,
all  holders of Common Stock are entitled  to participate pro rata in the assets
of the Company available for distribution, subject to the rights of any class of
preferred stock then outstanding. All of the outstanding shares of Common  Stock
are, and the shares to be issued pursuant to this offering will be, when issued,
fully paid and nonassessable.
    
 
PREFERRED STOCK
 
    Effective  upon the closing of this offering, the Company will be authorized
to issue up to 5,000,000 shares of Preferred Stock. The Board of Directors  will
have  the authority to issue  this Preferred Stock in one  or more series and to
fix the  rights, preferences,  privileges  and restrictions  thereof,  including
dividend  rights,  dividend rates,  conversion rights,  voting rights,  terms of
redemption, redemption prices, liquidation preferences and the number of  shares
constituting  any series of the designation of such series, without further vote
or action by  the stockholders.  The issuance of  Preferred Stock  may have  the
effect  of delaying, deferring or preventing a  change in control of the Company
without further action by the stockholders  and may adversely affect the  voting
and  other rights of the  holders of Common Stock,  including the loss of voting
control to others.  Prior to  the date hereof,  there were  3,000,000 shares  of
Preferred Stock outstanding held by 19 shareholders of record, which shares will
be  automatically converted into 2,000,000 shares of Common Stock on the date of
this Prospectus,  and  the shares  of  Preferred  Stock will  be  cancelled  and
retired.
 
REGISTRATION RIGHTS
 
   
    Beginning  one  year  from the  date  of this  Prospectus,  Bristol-Myers is
entitled to certain registration rights with respect to 874,999 shares of Common
Stock (including 333,333 shares to be purchased in a private placement upon  the
closing  of this offering) and 444,444 shares issuable upon exercise of warrants
(which amounts assume an initial public offering price of $15.00 per share) and,
beginning 13  months  from the  date  of  this Prospectus,  certain  holders  of
1,157,344  shares  of  Common Stock  and  the  holders of  211,315  warrants are
entitled to certain  registration rights  with respect  to such  shares and  the
Common  Stock  issuable  upon exercise  of  the warrants.  Under  the agreements
between the Company and these holders, the holders may request that the  Company
file  a registration statement  under the Securities Act  and, upon such request
and subject to certain  minimum size conditions, the  Company generally will  be
required  to use its best efforts to  effect any such registration. In addition,
if the Company proposes to register any of its Common Stock, either for its  own
account  or for the account of other stockholders, the Company is required, with
certain exceptions, to notify the holders
    
 
                                       47
<PAGE>
described above  and,  subject  to  certain  limitations,  to  include  in  such
registration  all of the shares of Common Stock requested to be included by such
holders. The Company  is generally obligated  to bear the  expenses, other  than
underwriting discounts and sales commissions, of all of these registrations.
 
    Any  exercise of such registration rights  may hinder efforts by the Company
to arrange future financings of the Company and/or have an adverse effect on the
market price of the Company's shares.
 
TRANSFER AGENT AND REGISTRAR
 
    American Stock Transfer and Trust Company,  New York, New York, will act  as
transfer agent and registrar for the Common Stock.
 
                        SHARES ELIGIBLE FOR FUTURE SALE
 
   
    Upon  completion of  this offering  and the  sale of  the BMS  Shares by the
Company, the Company will  have 11,993,912 shares  of Common Stock  outstanding,
assuming  that  the Underwriters'  over-allotment  option and  other outstanding
options and warrants are  not exercised. Of these  shares, the 3,200,000  shares
offered   hereby  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 ("Rule
144")  described  below.  The   remaining  8,793,912  shares  outstanding   upon
completion  of this offering are "restricted securities" as that term is defined
under Rule 144  (the "Restricted Shares")  and may not  be sold publicly  unless
they are registered under the Securities Act or are sold pursuant to Rule 144 or
another  exemption from registration. Approximately  3,424,290 of the Restricted
Shares will  become eligible  for sale  immediately following  the date  of  the
Prospectus  and, subject to  compliance with Rule 144  under the Securities Act,
approximately 2,925,714 of the  Restricted Shares will be  eligible for sale  in
the  public  market beginning  90 days  from  the date  of this  Prospectus. The
remaining Restricted Shares will become eligible  for sale pursuant to the  Rule
144  between June 1996 and June 1998. In addition, the Company intends to file a
Form S-8 to  register an aggregate  of 1,750,000 shares  subject to  outstanding
options or reserved for issuance pursuant to the Company's stock option plans.
    
 
   
    Beginning 90 days after the date of this Prospectus, certain shares 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 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,  as of  March 31,  1996, an  aggregate of  approximately 855,930  shares of
Common Stock issuable  upon exercise  of currently outstanding  options will  be
eligible for sale pursuant to such rule.
    
 
   
    Notwithstanding  the  foregoing, at  the  request of  the  Underwriters, the
Company and the  holders of  approximately 96.5%  of the  outstanding shares  of
Common  Stock,  including  each  stockholder  holding in  excess  of  1%  of the
outstanding shares and each executive officer and director of the Company,  have
agreed  not to sell or  otherwise dispose of any  shares of the Company's Common
Stock without the  prior written  consent of  Allen &  Company Incorporated,  on
behalf  of the Underwriters, for a period of 180 days after the date hereof. See
"Underwriting."
    
 
    In general under Rule 144, a person (or persons whose shares are aggregated)
who has beneficially owned Restricted Shares  for at least two years,  including
persons  who may be deemed to be  "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 (i) one percent of the then outstanding shares of Common Stock or
(ii)  the average  weekly trading  volume in  the Common  Stock during  the four
calendar weeks preceding  such sale. Sales  under Rule 144  are also subject  to
certain requirements as to the manner of
 
                                       48
<PAGE>
   
sale,  notice  and  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 a  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. Moreover,  the Securities and Exchange  Commission
has  recently proposed an  amendment to the holding  period requirements of Rule
144 to permit resales of restricted  securities after a one-year holding  period
rather  than a  two-year holding period,  and to permit  unrestricted resales by
non-affiliates pursuant to Rule  144(k) after a  two-year holding period  rather
than  a three-year holding period.  In the event that  such proposal is adopted,
the dates upon which certain of  the Restricted Shares will become eligible  for
sale pursuant to Rule 144 will be accelerated.
    
 
    Certain  holders of Common Stock and  warrants to purchase Common Stock have
certain demand and piggy-back registration  rights. See "Description of  Capital
Stock -- Registration Rights."
 
    Prior to this offering, there has been no market for the Common Stock of the
Company,  and the  Company cannot  predict what  effect, if  any, that  sales of
Common Stock or  the availability  of Common  Stock for  sale will  have on  the
market  price of  such securities  prevailing from  time to  time. Nevertheless,
sales of  substantial  amounts  of  Common Stock  in  the  public  market  could
adversely  affect prevailing  market prices  and the  ability of  the Company to
raise equity capital in the future.
 
                                       49
<PAGE>
                                  UNDERWRITING
 
    The Underwriters named below, for whom Allen & Company Incorporated, Dillon,
Read & Co. Inc. and  Volpe, Welty & Company  are acting as representatives  (the
"Representatives"),  have severally agreed, subject  to the terms and conditions
contained in  the  Underwriting Agreement,  to  purchase from  the  Company  the
aggregate  number  of shares  of  Common Stock  set  forth below  opposite their
respective names:
 
   
<TABLE>
<CAPTION>
                                                                                                        NUMBER OF
                                             UNDERWRITER                                                 SHARES
- -----------------------------------------------------------------------------------------------------  -----------
<S>                                                                                                    <C>
Allen & Company Incorporated.........................................................................
Dillon, Read & Co. Inc...............................................................................
Volpe, Welty & Company...............................................................................
 
                                                                                                       -----------
    Total............................................................................................    3,200,000
                                                                                                       -----------
                                                                                                       -----------
</TABLE>
    
 
    Pursuant to  the  Underwriting  Agreement,  the  several  Underwriters  have
agreed,  subject to the terms and conditions  set forth therein, to purchase all
of the shares  of Common Stock  offered hereby  (other than shares  that may  be
purchased   under  the  over-allotment   option)  if  any   are  purchased.  The
Underwriters propose initially to  offer the shares to  the public at the  price
set  forth on the  cover page of  this Prospectus. The  Underwriters may allow a
selling concession not  exceeding $      per share  of Common  Stock to  certain
dealers.  The Underwriters may allow, and such dealers may reallow, a concession
not in excess of $    per share to other dealers. The public offering price  and
concessions  may  be changed  by the  Representatives  after the  initial public
offering.
 
    The Company has  agreed to reimburse  the Representatives amounts  up to  an
aggregate of $200,000 toward their out-of-pocket expenses incurred in connection
with this offering.
 
   
    The Company has granted to the Underwriters an option expiring 30 days after
the  date of the Underwriting Agreement, to purchase up to an additional 480,000
shares of Common Stock at the public offering price, less underwriting discounts
and commissions, all  as set forth  on the  cover page of  this Prospectus.  The
Underwriters  may exercise the option only  to cover over-allotments, if any, in
the sale of  shares of Common  Stock in this  offering. To the  extent that  the
Underwriters  exercise their option, each Underwriter will be committed, subject
to  certain  conditions,  to  purchase  a  number  of  such  additional   shares
proportionate to such Underwriter's initial commitment.
    
 
   
    Bristol-Myers has agreed to purchase from the Company in a private placement
on the closing of this offering $5,000,000 of Common Stock at the initial public
offering  price (333,333  shares, assuming an  initial public  offering price of
$15.00 per  share).  Bristol-Myers, which  is  an existing  stockholder  of  the
Company,  has agreed not to sell, offer  for sale, contract to sell or otherwise
dispose of any  shares of  Common Stock or  any securities  convertible into  or
exercisable for shares of Common Stock or any rights to acquire Common Stock for
a  period of 180 days after the  date this Prospectus, without the prior written
consent of Allen & Company Incorporated, on behalf of the Underwriters.
    
 
   
    At the  request  of  the  Underwriters,  the  Company  and  the  holders  of
approximately  96.5% of the  outstanding shares of  Common Stock, including each
stockholder holding in excess of 1% of the outstanding shares and each executive
officer and director of the  Company, have agreed not  to sell, offer for  sale,
contract  to sell  or otherwise  dispose of  any shares  of Common  Stock or any
securities
    
 
                                       50
<PAGE>
convertible into or  exercisable for  shares of Common  Stock or  any rights  to
acquire  Common Stock for a  period of 180 days  after the date this Prospectus,
without the prior written consent of Allen & Company Incorporated, on behalf  of
the Underwriters.
 
    The  Company  and  the Underwriters  have  agreed to  indemnify  one another
against certain liabilities, including liabilities under the Securities Act.
 
    Prior to  this offering,  there has  been no  public market  for the  Common
Stock.  The initial public offering price will be negotiated between 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 the prevailing
market  conditions,  will  be  the  Company's  historical  performance,  capital
structure, estimates of  the business  potential and earnings  prospects of  the
Company,  an assessment  of the  Company's management  and consideration  of the
above factors  in  relation  to  market  values  of  the  companies  in  related
businesses.  The Representatives have informed the Company that the Underwriters
do  not  intend  to  confirm  sales   to  accounts  over  which  they   exercise
discretionary authority.
 
                                 LEGAL MATTERS
 
    The  validity  of the  shares offered  hereby  will be  passed upon  for the
Company by  Bachner,  Tally, Polevoy  &  Misher LLP,  New  York, New  York.  The
statements  in this Prospectus under the captions "Risk Factors -- Dependence on
Patents and  Other  Proprietary  Rights;  Uncertainty  of  Patent  Position  and
Proprietary  Rights" and "Business -- Patents  and Proprietary Rights" and other
references herein to patent matters have been reviewed and will be passed on  by
Jones  & Askew, Atlanta, Georgia, patent counsel  to the Company. As a condition
to consummation of this offering, Arnold & Porter, Washington, D.C., will render
to the  Underwriters  its opinion  that,  without having  verified  any  factual
statements  in  this Prospectus  and subject  to  certain assumptions  and other
qualifications stated in such opinion,  the statements in this Prospectus  under
the  caption "Risk Factors -- Uncertainty of Government Regulatory Requirements;
Lengthy Approval Process" and "Business -- Government Regulation" to the  extent
they  reflect legal matters arising under  federal laws administered by the U.S.
Food and Drug Administration fairly summarize the material legal and  regulatory
requirements of such laws currently applicable to the Company's products as they
are  described in this Prospectus. Certain legal matters will be passed upon for
the Underwriters by  Werbel McMillin &  Carnelutti, A Professional  Corporation,
New York, New York.
 
                                    EXPERTS
 
    The financial statements of EntreMed, Inc. at December 31, 1994 and 1995 and
for  each of the three years in the  period ended December 31, 1995 appearing in
this Prospectus and Registration  Statement have been audited  by Ernst &  Young
LLP,  independent  auditors,  as set  forth  in their  report  thereon appearing
elsewhere herein, and are included in  reliance upon such report given upon  the
authority of such firm as experts in accounting and auditing.
 
                             ADDITIONAL INFORMATION
 
    The  Company  has  filed a  Registration  Statement  on Form  S-1  under the
Securities Act with the Securities and Exchange Commission (the "Commission") in
Washington, D.C. with respect to the shares of Common Stock offered hereby. This
Prospectus, which is part of the Registration Statement, does not contain all of
the information set  forth in the  Registration Statement and  the exhibits  and
schedules  thereto. For further information with  respect to the Company and the
Common Stock  offered  hereby, reference  is  hereby made  to  the  Registration
Statement and such exhibits and schedules, which may be inspected without charge
at  the office  of the  Commission at 450  Fifth Street,  N.W., Washington, D.C.
20549. Reports and other  information filed by the  Company with the  Commission
can be inspected and copied at the public reference facilities maintained by the
Commission at the
 
                                       51
<PAGE>
following  addresses: New  York Regional Office,  Seven World  Trade Center, New
York, New York  10048; and Chicago  Regional Office, Citicorp  Center, 500  West
Madison  Street, Chicago,  Illinois 60661-2511. Copies  of such  material can be
obtained from  the Public  Reference  Section of  the  Commission at  450  Fifth
Street,  N.W., Washington, D.C. 20549  at prescribed rates. Statements contained
in this Prospectus as to the contents of any contract or other document referred
to are not necessarily complete  and in each instance  reference is made to  the
copy  of  such contract  or document  filed  as an  exhibit to  the Registration
Statement,  each  such  statement  being  qualified  in  all  respects  by  such
reference.
 
                                       52
<PAGE>
   
                                 ENTREMED, INC.
                         INDEX TO FINANCIAL STATEMENTS
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
    
 
   
<TABLE>
<CAPTION>
Report of Independent Auditors........................................................  F-2
<S>                                                                                     <C>
Balance Sheets as of December 31, 1994 and 1995 and March 31, 1996....................  F-3
Statements of Operations for the years ended December 31, 1993, 1994 and 1995 and for
 the three months ended March 31, 1995 and 1996.......................................  F-4
Statements of Stockholders' Equity for the years ended December 31, 1993, 1994 and
 1995 and for the three months ended March 31, 1995 and 1996..........................  F-5
Statements of Cash Flows for the years ended December 31, 1993, 1994 and 1995 and for
 the three months ended March 31, 1995 and 1996.......................................  F-6
Notes to Financial Statements.........................................................  F-7
</TABLE>
    
 
                                      F-1
<PAGE>
                         REPORT OF INDEPENDENT AUDITORS
 
Board of Directors
EntreMed, Inc.
 
    We  have audited  the accompanying  balance sheets  of EntreMed,  Inc. 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.  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 EntreMed, Inc. at December
31, 1994 and 1995 and the results of its operations and its cash flows for  each
of  the three years  in the period  ended December 31,  1995, in conformity with
generally accepted accounting principles.
 
                                           ERNST & YOUNG LLP
 
   
Atlanta, Georgia
January 25, 1996,
except for Note 13, as to which the date is
March 29, 1996
    
 
                                      F-2
<PAGE>
                                 ENTREMED, INC.
                                 BALANCE SHEETS
 
                                     ASSETS
 
   
<TABLE>
<CAPTION>
                                                                             MARCH 31, 1996
                                                  DECEMBER 31,         --------------------------
                                           --------------------------                 PRO FORMA
                                               1994          1995         ACTUAL       (NOTE 1)
                                           ------------  ------------  ------------  ------------
                                                                              (UNAUDITED)
<S>                                        <C>           <C>           <C>           <C>
Current assets:
  Cash and cash equivalents..............  $    218,619  $  6,885,099  $  7,600,058  $  7,600,058
  Account receivable.....................            --     2,500,000       100,000       100,000
  Interest receivable....................            --         4,016        15,389        15,389
                                           ------------  ------------  ------------  ------------
Total current assets.....................       218,619     9,389,115     7,715,447     7,715,447
Furniture and equipment, net.............       605,006       754,399       744,410       744,410
Other assets:
  Deposits...............................           894           894           894           894
  Other..................................        19,223         1,975       146,098       146,098
                                           ------------  ------------  ------------  ------------
Total other assets.......................        20,117         2,869       146,992       146,992
                                           ------------  ------------  ------------  ------------
Total assets.............................  $    843,742  $ 10,146,383  $  8,606,849  $  8,606,849
                                           ------------  ------------  ------------  ------------
                                           ------------  ------------  ------------  ------------
</TABLE>
    
 
                      LIABILITIES AND STOCKHOLDERS' EQUITY
 
   
<TABLE>
<S>                                             <C>            <C>            <C>            <C>
Current liabilities:
  Accounts payable............................  $     551,046  $     367,250  $   1,405,643  $   1,405,643
  Accrued liabilities.........................             --        341,776        501,788        501,788
  Capital lease obligations...................             --        396,113        404,233        404,233
  Deferred revenue............................             --      2,594,166      1,676,665      1,676,665
                                                -------------  -------------  -------------  -------------
  Total current liabilities...................        551,046      3,699,305      3,988,329      3,988,329
Capital lease obligations, less current
 portion......................................             --        104,152             --             --
Deferred revenue, less current portion........             --      2,741,666      2,566,667      2,566,667
Stockholders' equity:
  Convertible preferred stock, $1.00 par value
   and $1.50 liquidation value:
    5,000,000 shares authorized, 3,000,000
     shares issued and outstanding; 8,000,000
     shares authorized, 3,000,000 shares
     issued and outstanding as of March 31,
     1996 (unaudited).........................      3,000,000      3,000,000      3,000,000             --
  Common stock, $0.01 par value:
    20,000,000 shares authorized, 5,064,101
     and 6,376,588 shares issued and
     outstanding at December 31, 1994 and
     1995, respectively; 27,000,000 shares
     authorized, 6,460,579 shares issued and
     outstanding as of March 31, 1996
     (unaudited)..............................         50,641         63,766         64,606         84,606
  Additional paid-in capital..................     10,020,807     21,024,465     21,149,625     24,129,625
  Accumulated deficit.........................    (12,778,752)   (20,486,971)   (22,162,378)   (22,162,378)
                                                -------------  -------------  -------------  -------------
Total stockholders' equity....................        292,696      3,601,260      2,051,853      2,051,853
                                                -------------  -------------  -------------  -------------
Total liabilities and stockholders' equity....  $     843,742  $  10,146,383  $   8,606,849  $   8,606,849
                                                -------------  -------------  -------------  -------------
                                                -------------  -------------  -------------  -------------
</TABLE>
    
 
                            See accompanying notes.
 
                                      F-3
<PAGE>
                                 ENTREMED, INC.
                            STATEMENTS OF OPERATIONS
 
   
<TABLE>
<CAPTION>
                                                       YEAR ENDED DECEMBER 31,               THREE MONTHS ENDED MARCH 31,
                                            ----------------------------------------------  ------------------------------
                                                 1993            1994            1995            1995            1996
                                            --------------  --------------  --------------  --------------  --------------
                                                                                                     (UNAUDITED)
<S>                                         <C>             <C>             <C>             <C>             <C>
Revenues:
  Grant revenues..........................  $           --  $       90,185  $      347,001  $           --  $           --
  Collaborative research and
   development............................              --              --         347,501              --       1,042,500
  License fees............................              --              --          16,667              --          50,000
                                            --------------  --------------  --------------  --------------  --------------
                                                        --          90,185         711,169              --       1,092,500
Expenses:
  Research and development................       4,772,652       3,673,929       5,939,512       1,596,677       2,063,270
  General and administrative..............       1,552,143       1,549,705       2,458,976         455,342         771,411
                                            --------------  --------------  --------------  --------------  --------------
                                                 6,324,795       5,223,634       8,398,488       2,052,019       2,834,681
Interest expense..........................              --              --         (65,754)             --          (9,547)
Interest income...........................          85,939          18,993          44,854           5,559          76,321
                                            --------------  --------------  --------------  --------------  --------------
Net loss..................................  $   (6,238,856) $   (5,114,456) $   (7,708,219) $   (2,046,460) $   (1,675,407)
                                            --------------  --------------  --------------  --------------  --------------
                                            --------------  --------------  --------------  --------------  --------------
Pro forma net loss per share..............                                  $        (0.83)                 $        (0.18)
                                                                            --------------                  --------------
                                                                            --------------                  --------------
Pro forma weighted average number of
 shares outstanding.......................                                       9,271,943                       9,312,035
                                                                            --------------                  --------------
                                                                            --------------                  --------------
</TABLE>
    
 
                            See accompanying notes.
 
                                      F-4
<PAGE>
                                 ENTREMED, INC.
                       STATEMENTS OF STOCKHOLDERS' EQUITY
   
<TABLE>
<CAPTION>
                                        COMMON STOCK           PREFERRED STOCK        ADDITIONAL      STOCK
                                    ---------------------  ------------------------    PAID-IN     SUBSCRIPTION   ACCUMULATED
                                      SHARES     AMOUNT      SHARES       AMOUNT       CAPITAL      RECEIVABLE      DEFICIT
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
<S>                                 <C>         <C>        <C>          <C>          <C>           <C>           <C>
Balance at January 1, 1993........   3,311,600  $  33,115    3,000,000  $ 3,000,000  $     16,560   $ (100,000)  $  (1,425,440)
  Issuance of common stock at
   $.015 per share ($6.00 fair
   value) for research and
   development costs..............      66,666        667           --           --       399,333           --              --
  Sale of common stock at $6.00
   per share, net of offering
   costs of approximately
   $89,000........................   1,183,696     11,837           --           --     7,001,766           --              --
  Payment of stock subscription...          --         --           --           --            --      100,000              --
  Net loss........................          --         --           --           --            --           --      (6,238,856)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
Balance at December 31, 1993......   4,561,962     45,619    3,000,000    3,000,000     7,417,659           --      (7,664,296)
  Issuance of common stock for
   options exercised at $1.50 per
   share..........................      33,331        333           --           --        49,667           --              --
  Issuance of common stock for
   compensation to employees at
   $6.00 per share................      15,660        157           --           --        93,843           --              --
  Issuance of common stock for
   consulting services at $6.00
   per share......................       6,666         67           --           --        39,933           --              --
  Sale of common stock at $6.38
   per share, net of offering
   costs of approximately
   $422,000.......................     446,482      4,465           --           --     2,419,705           --              --
  Net loss........................          --         --           --           --            --           --      (5,114,456)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
Balance at December 31, 1994......   5,064,101     50,641    3,000,000    3,000,000    10,020,807           --     (12,778,752)
  Issuance of common stock for
   options exercised at $1.50 per
   share..........................      42,663        427           --           --        63,573           --              --
  Issuance of common stock for
   compensation to directors at
   $6.38 per share................      12,150        121           --           --        77,379           --              --
  Sale of common stock at $6.38
   per share, net of offering
   costs of approximately
   $180,000.......................     710,862      7,109           --           --     4,306,382           --              --
  Sale of common stock in
   connection with research
   agreement at $12.00 per share..     541,666      5,417           --           --     6,494,583           --              --
  Sale of common stock at $12.00
   per share......................       5,146         51           --           --        61,741           --              --
  Net loss........................          --         --           --           --            --           --      (7,708,219)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
Balance at December 31, 1995......   6,376,588  $  63,766    3,000,000  $ 3,000,000  $ 21,024,465   $       --   $ (20,486,971)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
Issuance of common stock for
 option exercised at $1.50 per
 share (unaudited)................      83,991        840           --           --       125,160           --              --
Net loss (unaudited)..............          --         --           --           --            --           --      (1,675,407)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
Balance at March 31, 1996
 (unaudited)......................   6,460,579  $  64,606    3,000,000  $ 3,000,000    21,149,625   $       --   $ (22,162,378)
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
                                    ----------  ---------  -----------  -----------  ------------  ------------  -------------
 
<CAPTION>
 
                                       TOTAL
                                    ------------
<S>                                 <C>
Balance at January 1, 1993........  $  1,524,235
  Issuance of common stock at
   $.015 per share ($6.00 fair
   value) for research and
   development costs..............       400,000
  Sale of common stock at $6.00
   per share, net of offering
   costs of approximately
   $89,000........................     7,013,603
  Payment of stock subscription...       100,000
  Net loss........................    (6,238,856)
                                    ------------
Balance at December 31, 1993......     2,798,982
  Issuance of common stock for
   options exercised at $1.50 per
   share..........................        50,000
  Issuance of common stock for
   compensation to employees at
   $6.00 per share................        94,000
  Issuance of common stock for
   consulting services at $6.00
   per share......................        40,000
  Sale of common stock at $6.38
   per share, net of offering
   costs of approximately
   $422,000.......................     2,424,170
  Net loss........................    (5,114,456)
                                    ------------
Balance at December 31, 1994......       292,696
  Issuance of common stock for
   options exercised at $1.50 per
   share..........................        64,000
  Issuance of common stock for
   compensation to directors at
   $6.38 per share................        77,500
  Sale of common stock at $6.38
   per share, net of offering
   costs of approximately
   $180,000.......................     4,313,491
  Sale of common stock in
   connection with research
   agreement at $12.00 per share..     6,500,000
  Sale of common stock at $12.00
   per share......................        61,792
  Net loss........................    (7,708,219)
                                    ------------
Balance at December 31, 1995......  $  3,601,260
                                    ------------
Issuance of common stock for
 option exercised at $1.50 per
 share (unaudited)................       126,000
Net loss (unaudited)..............    (1,675,407)
                                    ------------
Balance at March 31, 1996
 (unaudited)......................  $  2,051,853
                                    ------------
                                    ------------
</TABLE>
    
 
                            See accompanying notes.
 
                                      F-5
<PAGE>
                                 ENTREMED, INC.
                            STATEMENTS OF CASH FLOWS
 
   
<TABLE>
<CAPTION>
                                                                                                THREE MONTHS ENDED
                                                          YEAR ENDED DECEMBER 31,                   MARCH 31,
                                                  ----------------------------------------  --------------------------
                                                      1993          1994          1995          1995          1996
                                                  ------------  ------------  ------------  ------------  ------------
                                                                                                   (UNAUDITED)
<S>                                               <C>           <C>           <C>           <C>           <C>
CASH FLOWS FROM OPERATING ACTIVITIES
Net loss........................................  $ (6,238,856) $ (5,114,456) $ (7,708,219) $ (2,046,460) $ (1,675,408)
Adjustments to reconcile net loss to net cash
 used by operating activities:
  Depreciation and amortization.................        83,270       153,015       201,593        48,457        48,124
  Stock issued for compensation and consulting
   expense......................................       399,000       134,000        77,500            --            --
  Deferred revenue..............................            --            --     5,335,832            --    (1,092,500)
  Changes in assets and liabilities:
    Account receivable..........................            --            --    (2,500,000)           --     2,400,000
    Other assets................................        12,346            --            --        13,120       (44,665)
    Accounts payable............................        13,471       475,119      (183,796)       78,553     1,198,405
    Accrued liabilities.........................            --            --       341,776            --            --
    Deposits....................................        75,659            --            --            --            --
    Interest receivable.........................        20,050            --        (4,016)           --       (11,373)
                                                  ------------  ------------  ------------  ------------  ------------
Net cash used by operating activities...........    (5,635,060)   (4,352,322)   (4,439,330)   (1,906,330)      822,583
CASH FLOWS FROM INVESTING ACTIVITIES
Investments.....................................            --            --            --            --      (100,000)
Purchases of furniture and equipment............      (689,950)      (91,894)     (210,829)      (34,386)      (37,592)
                                                  ------------  ------------  ------------  ------------  ------------
Net cash used by investing activities...........      (689,950)      (91,894)     (210,829)      (34,386)     (137,592)
CASH FLOWS FROM FINANCING ACTIVITIES
Proceeds from sale lease-back...................            --            --       654,020            --            --
Payment of lease obligation.....................            --            --      (276,664)           --       (96,032)
Sales of common stock...........................     7,014,603     2,474,170    10,939,283     1,783,227       126,000
Repayment of note payable.......................            --            --      (510,000)           --            --
Proceeds from note payable......................            --            --       510,000            --            --
Sales of preferred stock........................       100,000            --            --            --            --
                                                  ------------  ------------  ------------  ------------  ------------
Net cash provided by financing activities.......     7,114,603     2,474,170    11,316,639     1,783,227        29,968
Net increase (decrease) in cash and cash
 equivalents....................................       789,593    (1,970,046)    6,666,480      (157,489)      714,959
Cash and cash equivalents at beginning of
 period.........................................     1,399,072     2,188,665       218,619       218,619     6,885,099
                                                  ------------  ------------  ------------  ------------  ------------
Cash and cash equivalents at end of period......  $  2,188,665  $    218,619  $  6,885,099  $     61,130  $  7,600,058
                                                  ------------  ------------  ------------  ------------  ------------
                                                  ------------  ------------  ------------  ------------  ------------
SUPPLEMENTAL DISCLOSURE OF CASH FLOW INFORMATION
 AND NONCASH INVESTMENT AND FINANCING ACTIVITIES
Interest paid...................................  $         --  $         --  $     65,754  $         --  $      9,547
                                                  ------------  ------------  ------------  ------------  ------------
                                                  ------------  ------------  ------------  ------------  ------------
Equipment purchased under capital lease.........  $         --  $         --  $    122,909  $         --  $         --
                                                  ------------  ------------  ------------  ------------  ------------
                                                  ------------  ------------  ------------  ------------  ------------
</TABLE>
    
 
                            See accompanying notes.
 
                                      F-6
<PAGE>
                                 ENTREMED, INC.
                         NOTES TO FINANCIAL STATEMENTS
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
1.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES
 
    DESCRIPTION OF BUSINESS AND BASIS OF PRESENTATION
 
    EntreMed,  Inc. (the  "Company") is  engaged primarily  in the  research and
development of biopharmaceutical  products that  address the role  of blood  and
blood  vessels in the prevention and treatment of a broad range of diseases. The
Company's core technologies include (i)  an antiangiogenesis program focused  on
the  development of proprietary products intended to inhibit the abnormal growth
the new blood vessels associated with cancer and certain causes of blindness and
(ii) a blood cell permeation device designed to enhance the ability of red blood
cells to deliver  oxygen to organs  and tissues and  which may also  be used  to
deliver  drugs,  genes  or other  therapeutic  agents that  otherwise  would not
readily diffuse through blood cell membranes.
 
    The Company's strategy is to accelerate development of its  antiangiogenesis
and  cell permeation technologies as well  as other promising technologies which
the Company perceives to have  clinical and commercial potential. The  principal
elements  of the Company's  strategy are (i)  to focus its  resources on current
core technologies, (ii) to broaden its product and technology portfolio  through
sponsored   research  collaborations  with   academic  institutions,  government
organizations and private enterprises, (iii) to augment product development with
its in-house  research and  development capabilities  and (iv)  to leverage  its
resources  through corporate partnerships  in order to minimize  the cost to the
Company of  late-stage  clinical  trials and  to  accelerate  effective  product
commercialization.   All  of  the  Company's  product  candidiates  are  in  the
development  stage  and  require  further  research,  development,  testing  and
regulatory clearances.
 
    The  Company was organized  in September 1991 as  a Delaware corporation and
from inception through December 1995 was  in the development stage. In  December
1995,  the Company  and Bristol-Myers  Squibb Company  ("Bristol-Myers") entered
into a  collaboration  to  develop and  commercialize  certain  antiangiogenesis
therapeutics  (see  Note  6).  The Company  received  approximately  50%  of its
revenues from Bristol-Myers in 1995  and expects this concentration to  increase
in future years.
 
    RESEARCH AND DEVELOPMENT
 
    Research   and  development  expenses  consist  of  independent  proprietary
research and development costs, the  costs associated with work performed  under
collaborative  research  agreements  and  the  Company's  sponsored  funding  of
research programs  performed  by  others. Research  and  development  costs  are
expensed as incurred.
 
    PATENT COSTS
 
   
    Costs  incurred in filing, prosecuting  and maintaining patents are expensed
as incurred. Such costs aggregated approximately $356,400, $455,800 and $454,600
in 1993,  1994 and  1995, respectively,  and $100,555  (unaudited) and  $109,834
(unaudited) for the three months ended March 31, 1995 and 1996, respectively.
    
 
    FURNITURE AND EQUIPMENT
 
    Furniture  and equipment are  stated at cost and  are depreciated over their
expected useful lives of five years. Depreciation is provided on a straight-line
basis. Amortization associated with capital  leases is included in  depreciation
expense.
 
    CASH EQUIVALENTS
 
    Cash  equivalents  include  cash and  short-term  investments  with original
maturities of less than 90 days.
 
                                      F-7
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
1.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
    INCOME TAXES
 
    Income taxes have  been provided  using the liability  method in  accordance
with FASB Statement No. 109, ACCOUNTING FOR INCOME TAXES.
 
    REVENUE RECOGNITION
 
   
    Revenues  related  to grants  received  for specific  project  proposals are
recognized in  revenue  as  earned  in  accordance  with  specified  provisions,
including   performance  requirements,  in  the   contracts.  Revenue  from  the
collaborative research and development agreement mentioned in Note 6 is recorded
when earned as  defined under  the terms  of the  agreement. Nonrefundable  fees
received  upon contract signing are recorded  as deferred revenue and recognized
over the  term  of  the  agreement. Other  periodic  research  funding  payments
received  which are related to future performance are deferred and recognized as
income when earned.
    
 
   
    UNAUDITED INTERIM FINANCIAL STATEMENTS
    
 
   
    The accompanying unaudited financial statements as of March 31, 1996 and for
the three month  periods ended March  31, 1995  and 1996 have  been prepared  in
accordance  with generally accepted accounting  principles for interim financial
information. Accordingly, such financial  statements do not  include all of  the
information and disclosures required by generally accepted accounting principles
for complete financial statements. In the opinion of management, all adjustments
(consisting  of  normal  recurring  accruals) considered  necessary  for  a fair
presentation have been  included. Operating results  for the three-month  period
ended  March 31, 1996 are not necessarily  indicative of the results that may be
expected for the year ended December 31, 1996.
    
 
   
    PRO FORMA BALANCE SHEET (UNAUDITED)
    
 
   
    The March 31, 1996 unaudited pro forma balance sheet reflects the  automatic
conversion  of 3,000,000  outstanding shares  of preferred  stock into 2,000,000
shares of common  stock upon  the effective  date of  a public  offering of  the
Company's common stock.
    
 
   
    PRO FORMA NET LOSS PER SHARE
    
 
   
    Pro forma net loss per share and weighted average shares outstanding for the
year  ended December 31,  1995 and the  three month period  ended March 31, 1996
give effect  to the  automatic  conversion of  3,000,000 outstanding  shares  of
preferred stock into 2,000,000 shares of common stock upon the effective date of
a  public offering  of the  Company's common  stock. Pursuant  to Securities and
Exchange Commission Staff  Accounting Bulletin  No. 83,  common and  convertible
preferred  stock  issued  for  consideration below  the  assumed  initial public
offering price of  $15.00 and stock  options and warrants  issued with  exercise
prices  below the assumed initial public  offering price during the twelve-month
period preceding the  initial filing  of the registration  statement, have  been
included  in the calculation of common  shares, using the treasury stock method,
as if they were outstanding for all  periods prior to the effective date of  the
initial public offering.
    
 
                                      F-8
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
1.  SUMMARY OF SIGNIFICANT ACCOUNTING POLICIES (CONTINUED)
   
    HISTORICAL NET LOSS PER SHARE
    
 
   
    The  historical net loss per share amounts as required by generally accepted
accounting principles, which do not give  effect to the pro forma conversion  of
preferred stock described above, are as follows:
    
 
   
<TABLE>
<CAPTION>
                                                                                                     THREE MONTH
                                                                                                     PERIOD ENDED
                                                               YEAR ENDED DECEMBER 31,                MARCH 31,
                                                        -------------------------------------  ------------------------
                                                           1993         1994         1995         1995         1996
                                                        -----------  -----------  -----------  -----------  -----------
<S>                                                     <C>          <C>          <C>          <C>          <C>
                                                                                                     (UNAUDITED)
Net loss per share....................................      $(1.04)      $(0.76)      $(1.06)      $(0.29)      $(0.23)
                                                        -----------  -----------  -----------  -----------  -----------
                                                        -----------  -----------  -----------  -----------  -----------
Weighted average common and common equivalent shares
 outstanding during the period........................    5,982,052    6,713,929    7,271,943    7,152,183    7,312,035
                                                        -----------  -----------  -----------  -----------  -----------
                                                        -----------  -----------  -----------  -----------  -----------
</TABLE>
    
 
    STOCK BASED COMPENSATION
 
    The  Company accounts for  stock options in accordance  with APB Opinion No.
25, ACCOUNTING FOR STOCK ISSUED TO EMPLOYEES. Under APB No. 25, no  compensation
expense is recognized for stock or stock options issued at fair market value.
 
    In October 1995, the FASB issued Statement of Financial Accounting Standards
No. 123, ACCOUNTING FOR STOCK BASED COMPENSATION ("SFAS 123"), which provides an
alternative  to APB No. 25 in accounting  for stock based compensation issued to
employees. SFAS 123  provides for a  fair value based  method of accounting  for
employee  stock options and  similar equity instruments.  However, for companies
that continue to account for stock based compensation arrangements under APB No.
25, SFAS 123  requires disclosure  of the  pro forma  effect on  net income  and
earnings  per share as if the fair value based method prescribed by SFAS 123 had
been applied.  The  disclosure  requirements  are  effective  for  fiscal  years
beginning after December 31, 1995, or upon initial adoption of the statement, if
earlier.  The Company plans to continue  to account for stock based compensation
arrangements under  APB No.  25 and  plans  to adopt  the pro  forma  disclosure
requirements of SFAS 123 in 1996.
 
    ESTIMATES
 
    The  preparation  of  financial  statements  in  conformity  with  generally
accepted  accounting  principles  requires  management  to  make  estimates  and
assumptions  that affect  the amounts reported  in the  financial statements and
accompanying notes. Actual results inevitably will differ from those  estimates,
and such differences may be material to the financial statements.
 
   
2.  RELATED PARTY TRANSACTIONS
    
    During  1995,  the  Company  borrowed  approximately  $510,000  from related
parties, of which  $162,916 was  borrowed from a  director of  the Company,  and
issued  its notes  payable at  9% interest.  Upon receipt  of proceeds  from the
collaborative research  and  development  agreement mentioned  in  Note  6,  the
Company paid the notes and accrued interest.
 
                                      F-9
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
3.  FURNITURE AND EQUIPMENT
    Furniture and equipment are summarized as follows:
 
<TABLE>
<CAPTION>
                                                                        DECEMBER 31,
                                                                 --------------------------
                                                                     1994          1995
                                                                 ------------  ------------
<S>                                                              <C>           <C>
Furniture and equipment........................................  $    840,369  $    941,226
Less: accumulated depreciation.................................      (235,363)     (186,827)
                                                                 ------------  ------------
                                                                 $    605,006  $    754,399
                                                                 ------------  ------------
                                                                 ------------  ------------
</TABLE>
 
4.  OPERATING LEASE
    The  Company leases its primary facilities through March 31, 2003. The lease
agreement provides for  escalation of the  lease payments over  the term of  the
lease,  however, rent expense is recognized  under the straight-line method. The
future minimum payments under the lease as of December 31, 1995 are as follows:
 
<TABLE>
<S>                                                              <C>
1996...........................................................  $  215,400
1997...........................................................     221,100
1998...........................................................     227,000
1999...........................................................     233,200
Thereafter.....................................................     723,600
                                                                 ----------
    Total minimum payments.....................................  $1,620,300
                                                                 ----------
                                                                 ----------
</TABLE>
 
    Rental expense for  the years  ended December 31,  1993, 1994  and 1995  was
$158,000, $187,000, and $210,000, respectively.
 
5.  SPONSORED RESEARCH PROGRAM AGREEMENTS
   
    During 1994 and 1995, the Company entered into several agreements to sponsor
external  research  programs. The  Company's  primary external  research program
agreement was entered  into in September  1993 with the  Children's Hospital  in
Boston,   Massachusetts,  an  entity  affiliated  with  Harvard  Medical  School
("Children's Hospital").  Under this  sponsored research  agreement the  Company
agreed to pay Children's Hospital $11,000,000 to support research on the role of
angiogenesis  in pathological conditions.  In accordance with  the terms of this
sponsored research agreement, $4,000,000 has been paid as of December 31,  1995,
$1,000,000 is due on April 1, 1996 and the remainder is due in equal semi-annual
payments  until  April  1, 1999.  This  sponsored research  agreement  gives the
Company  an   exclusive   option   to   negotiate   an   exclusive,   worldwide,
royalty-bearing  license  to  any  technology  resulting  from  the  research at
Children's Hospital in  areas covered by  the agreement. Amounts  due under  the
sponsored  research agreement with  Children's Hospital, which  is cancelable by
the Company upon six months' notice, are paid in advance each six months and are
expensed as incurred as research and development costs. As of December 31, 1995,
the Company's total commitments for external research programs are as follows:
    
 
<TABLE>
<S>                                                              <C>
1996...........................................................  $2,304,000
1997...........................................................   2,188,000
1998...........................................................   2,000,000
1999...........................................................   1,000,000
                                                                 ----------
    Total commitments..........................................  $7,492,000
                                                                 ----------
                                                                 ----------
</TABLE>
 
                                      F-10
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
   
6.  COLLABORATIVE RESEARCH AND DEVELOPMENT AGREEMENT
    
    In December 1995, the Company and Bristol-Myers entered into a collaboration
to  develop  and  commercialize  certain  antiangiogenesis  therapeutics.   This
collaboration  provides  for  Bristol-Myers to  fund  Company  research, provide
milestone payments to the Company, and pay the Company royalties on net sales of
any products developed under the  collaboration. In return, the Company  granted
Bristol-Myers  exclusive  worldwide  rights  to  antiangiogenic  applications of
thalidomide, thalidomide analogs and Angiostatin protein.
 
   
    Bristol-Myers is  obligated under  the Bristol-Myers  collaboration to  fund
$18.35 million in ten semi-annual payments of $1.835 million over five years for
costs  to  be  incurred  by  the  Company  related  to  specified  research  and
development. The Company may  receive an additional $32  million if the  Company
attains certain late-stage clinical development and regulatory filing milestones
under  the  Bristol-Myers collaboration,  a portion  of  which will  be credited
against royalties. In addition to  this funding, Bristol-Myers has committed  to
fund  $730,000 for  clinical studies and  ophthalmological trials. Bristol-Myers
may terminate this collaboration for any reason with six months notice, in which
event Bristol-Myers would have no further funding obligation to the Company.  In
the  event Bristol-Myers  were to  terminate the  Bristol-Myers collaboration or
otherwise fail to  conduct its  collaborative activities successfully  and in  a
timely  manner, the preclinical and clinical development or commercialization of
the Company's licensed antiangiogenesis product  candidates would be delayed  or
terminated.
    
 
    The  Company received a  non-refundable, non-creditable licensing  fee of $1
million in 1995  under the  Bristol-Myers collaboration and  an additional  $2.5
million  on March  31, 1996 in  recognition of certain  research and development
efforts of the Company. These amounts were recorded as deferred revenue and  are
being  recognized  over  five  years,  the  initial  term  of  the collaboration
agreement.
 
    Concurrent with the signing of the Bristol-Myers collaboration, the  Company
issued  Bristol-Myers 541,666 shares of common stock for aggregate cash proceeds
of $6,500,000. Bristol-Myers also agreed to purchase $5,000,000 (333,333 shares,
assuming an initial  public offering price  of $15.00 per  share) of  additional
common stock of the Company at the initial public offering price if and when the
Company  completes an initial public offering in  the future and was granted the
right to purchase an additional $10,000,000  of Company common stock at 150%  of
the  initial public offering  price (444,444 shares,  assuming an initial public
offering price of $15.00 per share) from the Company at any time up to one  year
from the effective date of the initial public offering.
 
   
    During  1995, the Company  recognized approximately $347,000  in revenue and
incurred  costs  of  approximately  $500,000  related  to  the  above  described
collaborative  research and  development agreement.  For the  three month period
ended March 31, 1996, the  Company recognized $1,092,500 (unaudited) in  revenue
and incurred costs of $1,351,930 (unaudited) under this agreement.
    
 
7.  SALE-LEASEBACK AGREEMENT
    During  1995, the Company  entered into a  sale-leaseback agreement which is
accounted for as a  capital lease. The lessor  agreed to purchase the  Company's
equipment  and also assumed and exercised the Company's purchase option on other
leased equipment. The Company agreed to lease-back the equipment over an initial
term of two  years with  annual renewal  options in  years three  and four.  The
Company has the option to purchase the equipment at fair market value at the end
of years two and
 
                                      F-11
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
7.  SALE-LEASEBACK AGREEMENT (CONTINUED)
three. If the option is not exercised the Company must purchase all equipment at
fair market value at the end of year four. In connection with the agreement, the
Company  granted the  lessor warrants  for 33,334 shares  of common  stock at an
exercise price of $6.38 per share.
 
    Capitalized leased  furniture  and equipment  with  a cost  of  $776,929  is
included in furniture and equipment (see Note 3).
 
    Future  minimum payments under this lease  agreement as of December 31, 1995
are as follows:
 
<TABLE>
<S>                                                                <C>
1996.............................................................  $ 422,314
1997.............................................................    105,570
                                                                   ---------
Total minimum lease payments.....................................    527,884
Less amount representing interest................................     27,619
                                                                   ---------
Present value of net minimum lease payments......................  $ 500,265
                                                                   ---------
                                                                   ---------
</TABLE>
 
8.  INCOME TAXES
    At December 31, 1995,  the Company has net  operating loss carryforwards  of
approximately  $17,100,000 for  income tax  purposes that  expire in  years 2006
through  2010.  The  Company  also  has  research  and  development  tax  credit
carryforwards  of  approximately $1,239,000  that expire  in years  2007 through
2010. The utilization  of the net  operating loss and  research and  development
carryforwards  may be limited in future years due to changes in ownership of the
Company pursuant to Internal Revenue  Code Section 382. For financial  reporting
purposes,  a valuation allowance has been  recognized to reduce the net deferred
tax assets to zero due to uncertainties with respect to the Company's ability to
generate taxable  income in  the future  sufficient to  realize the  benefit  of
deferred income tax assets.
 
    Deferred  income  taxes  reflect  the net  effect  of  temporary differences
between the carrying amounts of  assets and liabilities for financial  reporting
purposes and the amounts used for income tax purposes. Significant components of
the Company's deferred income tax assets and liabilities as of December 31, 1994
and 1995 are as follows:
 
<TABLE>
<CAPTION>
                                                                  1994            1995
                                                             --------------  --------------
<S>                                                          <C>             <C>
Deferred income tax assets (liability):
  Research and development credit carryforwards............  $    1,119,000  $    1,239,000
  Net operating loss carryforwards.........................       4,337,000       5,819,000
  Deferred revenues........................................              --         976,000
  Other....................................................          11,000         160,000
  Depreciation.............................................         (27,000)        (24,000)
  Valuation allowance for deferred income tax assets.......      (5,440,000)     (8,170,000)
                                                             --------------  --------------
    Net deferred income taxes..............................  $           --  $           --
                                                             --------------  --------------
                                                             --------------  --------------
</TABLE>
 
                                      F-12
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
8.  INCOME TAXES (CONTINUED)
    A  reconciliation of the provision for income taxes to the federal statutory
rate is as follows:
 
<TABLE>
<CAPTION>
                                                     1993            1994            1995
                                                --------------  --------------  --------------
<S>                                             <C>             <C>             <C>
Tax at statutory rate.........................  $   (2,121,000) $   (1,739,000) $   (2,621,000)
Tax credits...................................        (791,000)       (287,000)       (120,000)
Other.........................................           2,000           2,000          11,000
Valuation allowance...........................       2,910,000       2,024,000       2,730,000
                                                --------------  --------------  --------------
                                                $           --  $           --  $           --
                                                --------------  --------------  --------------
                                                --------------  --------------  --------------
</TABLE>
 
9.  CONVERTIBLE PREFERRED STOCK
    The preferred  stock  has  certain  preferential  rights  in  the  event  of
liquidation  or dissolution of the Company but  does not have any preferences in
regard to  voting  rights or  dividend  distributions. The  preferred  stock  is
convertible  into  the Company's  common stock  at the  option of  the preferred
stockholder. Upon  the effective  date of  a public  offering of  the  Company's
common  stock, the preferred  stock will automatically  be converted into common
stock. See Note 13.
 
10. STOCK OPTIONS AND WARRANTS
    The Company  adopted an  incentive  and nonqualified  stock option  plan  on
December  2, 1992, whereby  1,233,333 shares of the  Company's common stock were
reserved  for  grants  to  various  executive,  scientific  and   administrative
personnel  of the  Company as well  as outside directors  and consultants. These
options vest over periods  varying from vesting  immediately through four  years
and  generally expire 10 years from the  date of grant. Stock option activity is
as follows:
 
<TABLE>
<CAPTION>
                                                            NUMBER OF     EXERCISE PRICE
                                                             OPTIONS        PER SHARE
                                                           -----------  ------------------
<S>                                                        <C>          <C>
Outstanding at December 31, 1992.........................      333,337        $1.50
  Granted................................................      207,343    $1.50 - $ 6.00
                                                           -----------
Outstanding at December 31, 1993.........................      540,680    $1.50 - $ 6.00
  Granted................................................       63,340    $6.00 - $ 6.38
                                                           -----------
Outstanding at December 31, 1994.........................      604,020    $1.50 - $ 6.38
  Granted................................................      436,343    $6.00 - $12.00
                                                           -----------
Outstanding at December 31, 1995.........................    1,040,363    $1.50 - $12.00
                                                           -----------
                                                           -----------
Exercisable at December 31, 1995.........................      684,559
                                                           -----------
                                                           -----------
</TABLE>
 
    The Company also granted 83,334 and 50,000 options to purchase common  stock
at  $6.00 and $6.38 per share during  1993 and 1995, respectively, to Children's
Hospital in connection with a sponsored  research agreement (see Note 5).  These
options  are not covered by the incentive and nonqualified stock option plan and
are included in the table below.
 
                                      F-13
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
10. STOCK OPTIONS AND WARRANTS (CONTINUED)
    The Company also has granted  warrants to various executive, scientific  and
administrative   personnel  of  the  Company   as  well  as  outside  directors,
consultants, and certain third parties. Warrants granted generally expire  after
10 years from the date of grant. Stock warrant activity is as follows:
 
<TABLE>
<CAPTION>
                                                             NUMBER OF    EXERCISE PRICE
                                                             WARRANTS        PER SHARE
                                                            -----------  -----------------
<S>                                                         <C>          <C>
Outstanding at December 31, 1992..........................      600,000        $1.50
  Granted.................................................       83,334        $6.00
                                                            -----------
Outstanding at December 31, 1993..........................      683,334    $1.50 - $6.00
  Exercised...............................................      (33,331)       $1.50
  Granted.................................................       44,648        $7.65
                                                            -----------
Outstanding at December 31, 1994..........................      694,651    $1.50 - $7.65
  Exercised...............................................      (42,663)       $1.50
  Granted.................................................      706,669        $6.38
                                                            -----------
Outstanding at December 31, 1995..........................    1,358,657    $1.50 - $7.65
                                                            -----------
                                                            -----------
Exercisable at December 31, 1995..........................      980,879
                                                            -----------
                                                            -----------
</TABLE>
 
    The  Company also granted  warrants to Bristol-Myers  in connection with the
Bristol-Myers collaboration described in Note 6.
 
                                      F-14
<PAGE>
                                 ENTREMED, INC.
                   NOTES TO FINANCIAL STATEMENTS (CONTINUED)
                  YEARS ENDED DECEMBER 31, 1993, 1994 AND 1995
 
11. FINANCIAL INSTRUMENTS
    Financial instruments that  potentially subject the  Company to  significant
concentrations  of credit risk consist principally  of cash and cash equivalents
and account receivable.
 
    The Company  maintains  cash and  cash  equivalents with  various  financial
institutions.  The Company's policy is to limit exposure to any one institution.
The account receivable is due from Bristol-Myers.
 
    The following methods and assumptions were used by the Company in estimating
its fair value disclosures for financial instruments:
 
        CASH AND CASH EQUIVALENTS:  The carrying amount reported in the  balance
    sheet for cash and cash equivalents approximates their fair values.
 
        ACCOUNT  RECEIVABLE AND ACCOUNTS PAYABLE:  The carrying amounts reported
    in the  balance  sheet  for  the account  receivable  and  accounts  payable
    approximate their fair values.
 
        CAPITAL LEASE PAYABLE:  The fair value of the Company's capital lease is
    estimated  using  discounted  cash  flow analysis,  based  on  the Company's
    current  incremental  borrowing  rates   for  similar  types  of   borrowing
    arrangements.  The carrying  amount reported  in the  balance sheet  for the
    capital lease payable approximates its fair value.
 
12. COMMITMENTS AND CONTINGENCIES
   
    The Company is a party to certain litigation initiated in August 1995 in the
United States District Court for the  Eastern District of Tennessee by  Bolling,
McCool  & Twist,  a consulting firm.  The suit  relates to a  claim for services
rendered in the  approximate amount of  $50,000 and  seek a finder's  fee in  an
unspecified  amount in connection  with the Bristol-Myers  collaboration. Due to
the lack of discovery and early stage of the proceedings, the Company is  unable
to  predict  with certainty  the eventual  outcome of  the lawsuit.  The Company
intends to contest the action vigorously and believes that this proceeding  will
not  have  a  material  adverse  effect  on  the  Company  or  on  its financial
statements.
    
 
    The Company  is  obligated to  make  annual license  agreement  payments  of
$40,000  to a director  of the Company  for certain rights  to technologies. The
payments began on June 4, 1992 and conclude on June 4, 1996.
 
    In May 1994, the Company entered into a license agreement, which was amended
in 1995, whereby  the Company gained  the rights  to make, use,  lease and  sell
licensed  products  developed  by  Children's  Hospital.  In  consideration  for
receiving the rights, the Company must  pay a royalty on any sublicensing  fees,
as  defined  in  the agreement,  to  Children's  Hospital. The  Company  is also
required to pay certain amounts upon  the attainment of certain milestones.  The
milestone  payments aggregate  $2,650,000, of  which $290,000  has been  paid to
date, and are based upon license fees and achievement of regulatory approvals.
 
    In addition, the license  agreement requires the  Company to pay  Children's
Hospital a specified percentage of the royalty income received on the first $100
million  in  net sales  of the  licensed products,  and an  increased percentage
thereafter, with a minimum  payment based on  a percentage of  net sales of  the
licensed products by any sublicensees.
 
13. SUBSEQUENT EVENT
    On March 29, 1996, the Company's Board of Directors declared a two-for-three
reverse  stock split of the common stock to be effective, subject to stockholder
approval, retroactively to the date of inception (September 18, 1991). Upon such
effectiveness,  the  conversion  ratio  of  the  convertible  preferred   stock,
previously one-for-one, will be adjusted to reflect the reverse stock split. All
common stock, option information, weighted average shares and earnings per share
information has been retroactively restated to reflect the reverse stock split.
 
                                      F-15


<PAGE>











                        IHP-TREATED RED BLOOD CELLS


Organs and tissues in the body require oxygen to function properly. Inositol 
hexophosphate (IHP), a naturally occurring plant chemical, may enhance the 
oxygen releasing capabilities of red blood cells. This schematic illustrates 
IHP-treated red blood cells. EntreMed is developing a cell permeation 
technology to deliver IHP into red blood cells and which may also be used to 
deliver drugs, genes or other therapeutic agents that otherwise would  not 
readily diffuse through blood cell membranes.



<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,
AND,  IF GIVEN OR MADE,  SUCH INFORMATION OR REPRESENTATIONS  MUST NOT BE RELIED
UPON AS HAVING BEEN AUTHORIZED BY THE  COMPANY OR ANY OF THE UNDERWRITERS.  THIS
PROSPECTUS  DOES NOT CONSTITUTE AN  OFFER OF ANY SECURITIES  OTHER THAN THOSE TO
WHICH IT RELATES OR AN OFFER TO SELL,  OR A SOLICITATION OF AN OFFER TO BUY,  TO
ANY  PERSON IN  ANY JURISDICTION  WHERE SUCH AN  OFFER OR  SOLICITATION WOULD BE
UNLAWFUL. NEITHER THE DELIVERY  OF THIS PROSPECTUS NOR  ANY SALE MADE  HEREUNDER
SHALL,  UNDER  ANY CIRCUMSTANCES,  CREATE ANY  IMPLICATION THAT  THE INFORMATION
CONTAINED HEREIN IS CORRECT AS OF ANY TIME SUBSEQUENT TO THE DATE HEREOF.
 
                            ------------------------
 
                               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.......................................         21
Management.....................................         35
Certain Transactions...........................         43
Principal Stockholders.........................         45
Description of Capital Stock...................         47
Shares Eligible for Future Sale................         48
Underwriting...................................         50
Legal Matters..................................         51
Experts........................................         51
Additional Information.........................         51
Index to Financial Statements..................        F-1
</TABLE>
    
 
                            ------------------------
 
    UNTIL              , 1996 (25 DAYS AFTER  THE DATE OF THIS PROSPECTUS),  ALL
DEALERS EFFECTING TRANSACTIONS IN THE COMMON STOCK, WHETHER OR NOT PARTICIPATING
IN  THIS  DISTRIBUTION, MAY  BE REQUIRED  TO  DELIVER A  PROSPECTUS. THIS  IS IN
ADDITION TO THE OBLIGATIONS  OF DEALERS TO DELIVER  A PROSPECTUS WHEN ACTING  AS
UNDERWRITERS AND WITH RESPECT TO THEIR UNSOLD ALLOTMENTS OR SUBSCRIPTIONS.
 
   
                                3,200,000 SHARES
    
 
                                     [LOGO]
 
                                  COMMON STOCK
 
                             ---------------------
 
                              P R O S P E C T U S
                             ---------------------
 
                                ALLEN & COMPANY
                                  INCORPORATED
 
                            DILLON, READ & CO. INC.
 
VOLPE, WELTY & COMPANY
 
                                          , 1996
 
- -------------------------------------------
                                     -------------------------------------------
- -------------------------------------------
                                     -------------------------------------------
<PAGE>
                                    PART II
                     INFORMATION NOT REQUIRED IN PROSPECTUS
 
ITEM 13. OTHER EXPENSES OF ISSUANCE AND DISTRIBUTION
 
    The  estimated expenses  payable by  the Registrant  in connection  with the
issuance and  distribution  of  the  securities  being  registered  (other  than
underwriting discounts and commissions) are as follows:
 
   
<TABLE>
<CAPTION>
                                                                                     AMOUNT
                                                                                   -----------
<S>                                                                                <C>
SEC Registration Fee.............................................................  $    22,207
NASD Filing Fee..................................................................        6,940
Nasdaq Listing Fee...............................................................       47,500
Reimbursement of Underwriters' Expenses..........................................      200,000
Printing and Engraving Expenses..................................................      130,000
Accounting Fees and Expenses.....................................................       90,000
Legal Fees and Expenses..........................................................      310,000
Blue Sky Fees and Expenses.......................................................       40,000
Transfer Agent's Fees and Expenses...............................................       10,000
Travel and Miscellaneous Expenses................................................      143,353
                                                                                   -----------
    Total........................................................................    1,000,000
                                                                                   -----------
                                                                                   -----------
</TABLE>
    
 
- ------------------------
 *  To be completed by amendment
 
ITEM 14.  INDEMNIFICATION OF DIRECTORS AND OFFICERS
 
    The Certificate of Incorporation and By-Laws of the Registrant provides that
the  Company shall  indemnify any  person to  the full  extent permitted  by the
Delaware General Corporation Law (the "GCL").  Section 145 of the GCL,  relating
to indemnification, is hereby incorporated herein by reference.
 
    Insofar  as indemnification for liabilities under  the Securities Act may be
permitted to directors, officers or controlling persons of the Company  pursuant
to  the Company's By-laws and the  Delaware General Corporation Law, the Company
has been informed 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.
 
    The   Company's  Restated  Certificate  of  Incorporation  includes  certain
provisions permitted pursuant to Delaware law whereby officers and directors  of
the  Company are  to be indemnified  against certain  liabilities. The Company's
Restated Certificate  of  Incorporation  also  limits,  to  the  fullest  extent
permitted  by  Delaware law,  a director's  liability  for monetary  damages for
breach of fiduciary duty, including  gross negligence, except liability for  (i)
breach  of the director's  duty of loyalty,  (ii) acts or  omissions not in good
faith or which involve intentional misconduct or a knowing violation of the law,
(iii) the  unlawful  payment  of  a  dividend  or  unlawful  stock  purchase  or
redemption  and (iv) any transaction from which the director derives an improper
personal benefit. Delaware law does not eliminate a director's duty of care  and
this  provision has no effect on the  availability of equitable remedies such as
injunction or rescission based upon a director's breach of the duty of care.
 
    In accordance  with  Section  102(a)(7)  of  the  GCL,  the  Certificate  of
Incorporation  of the Registrant eliminates  the personal liability of directors
to the Company or its stockholders for monetary damages for breach of  fiduciary
duty  as  a  director  with  certain limited  exceptions  set  forth  in Section
102(a)(7).
 
                                      II-1
<PAGE>
    The Registrant also  intends to enter  into indemnification agreements  with
each  of its  executive officers and  directors, the  form of which  is filed as
Exhibit 10.16 hereto and reference is hereby made to such form.
 
    Reference is made to Section 6  of the Underwriting Agreement (Exhibit  1.1)
which  provides for indemnification  by the Underwriters  of the Registrant, its
officers and directors.
 
ITEM 15.  RECENT SALES OF UNREGISTERED SECURITIES
 
    The following  discussion  gives  retroactive effect  to  the  two-for-three
reverse stock split effected in April 1996. Since March 1993, the Registrant has
sold and issued the following unregistered securities:
 
    In  March  through  October  1993, the  Registrant  issued  an  aggregate of
1,183,696 shares of Common Stock to 77 accredited investors for a purchase price
of $6.00  per  share. The  shares  were issued  pursuant  to an  exemption  from
registration  provided by  Regulation D  promulgated under  Section 4(2)  of the
Securities Act.
 
   
    In April 1994, the Registrant issued 33,331 shares of Common Stock to Samuel
R. Dunlap,  Jr., a  director of  the Registrant,  upon the  exercise of  options
exercisable at $1.50 per share.
    
 
    In  May 1994, the Registrant issued 15,660  shares of Common Stock valued at
$6.00 per share to 18 employees in consideration for services rendered.
 
   
    In May 1994, the  Registrant issued 6,666 shares  of Common Stock valued  at
$6.00  per  share to  Bolling,  McCool &  Twist,  an independent  consultant, in
consideration for consulting services rendered.
    
 
    In September through November  1994, the Registrant  issued an aggregate  of
446,482  shares of Common Stock to 35  accredited investors for a purchase price
of $6.375  per share.  The shares  were  issued pursuant  to an  exemption  from
registration  provided by  Regulation D  promulgated under  Section 4(2)  of the
Securities Act. Josephthal Lyon and Ross Incorporated acted as the  Registrant's
placement  agent  in  connection  with  this  private  placement.  In connection
therewith, the Registrant paid sales commissions in the amount of  approximately
$228,000  and a  non-accountable expense  allowance in  the aggregate  amount of
approximately $31,000.
 
   
    In May through November 1995, the  Registrant issued an aggregate of  42,663
shares  of Common Stock to Samuel R.  Dunlap, Jr., a director of the Registrant,
upon the exercise of options exercisable at $1.50 per share.
    
 
    In May and  November 1995,  the Registrant  issued 12,150  shares of  Common
Stock  valued  at  $6.375  per  share to  ten  directors  of  the  Registrant in
consideration for services rendered.
 
    In December 1994 through September 1995, the Registrant issued an  aggregate
of  710,862 shares  of Common  Stock to 34  accredited investors  for a purchase
price of $6.375 per share. The shares were issued pursuant to an exemption  from
registration  provided by  Regulation D  promulgated under  Section 4(2)  of the
Securities Act. In  connection therewith,  the Registrant paid  an aggregate  of
approximately $175,000 in sales commissions.
 
    In  December  1995, the  Registrant issued  to Bristol-Myers  Squibb Company
541,666 shares of Common  Stock at a  purchase price of $12.00  per share and  a
warrant  to purchase  444,444 shares  of Common  Stock at  an exercise  price of
$22.50 (assuming an initial public offering price of $15.00 per share).
 
    In December 1995, the Registrant issued 5,149 shares of Common Stock  valued
at $12.00 per share to eight accredited investors.
 
                                      II-2
<PAGE>
   
    In  January through March 1996, the Registrant issued an aggregate of 84,000
shares of Common Stock to Samuel R.  Dunlap, Jr., a director of the  Registrant,
upon the exercise of stock options exercisable at $1.50 per share.
    
 
    Except  as otherwise  noted above, (i)  the above  transactions were private
transactions  not  involving  a  public  offering  and  were  exempt  from   the
registration  provisions of the Securities Act  of 1933, as amended, pursuant to
Section 4(2) thereof,  (ii) the sale  of securities  was without the  use of  an
underwriter  and (iii) the certificates evidencing the shares bear a restrictive
legend permitting the transfer thereof only  upon registration of the shares  or
an exemption under the Securities Act of 1933, as amended.
 
    The  above  transactions were  private transactions  not involving  a public
offering and were exempt from the registration provisions of the Securities  Act
of  1933,  as amended,  pursuant to  Section 4(2)  thereof. Except  as otherwise
indicated, the sale of securities was without the use of an underwriter, and the
certificates evidencing  the shares  bear a  restrictive legend  permitting  the
transfer  thereof only upon registration of the shares or an exemption under the
Securities Act of 1933, as amended.
 
ITEM 16.  EXHIBITS
 
   
<TABLE>
<C>        <S>
    1.1.   Revised Form of Underwriting Agreement
    3.1.*  Amended and Restated Certificate of Incorporation of the Registrant
    3.2*   Form of Certificate of Amendment to the Amended and Restated Certificate of
            Incorporation of the Registrant
    3.3*   By-laws of the Registrant
    5.1    Opinion of Bachner, Tally, Polevoy & Misher LLP
   10.1*   Research Collaboration and License Agreement, dated December 7, 1995, between the
            Registrant and Bristol-Myers Squibb Company ("BMS")
   10.2*   Restricted Stock Purchase Agreement, dated December 7, 1995, between the
            Registrant and BMS
   10.3*   Warrant to Purchase Common Stock, dated December 7, 1995, issued by the Registrant
            to BMS
   10.4*   Registration Rights Agreement, dated December 7, 1995, between the Registrant and
            BMS
   10.5*   Research Agreement, dated September 29, 1993, between the Registrant and
            Children's Hospital
   10.6*+  Amendment to Research Agreement, dated August 23, 1995, between the Registrant and
            Children's Hospital
   10.7*+  License Agreement, dated May 26, 1994, between Children's Medical Center
            Corporation ("CMCC") and the Registrant
   10.8*+  Amendment to License Agreement, dated August 23, 1995, between CMCC and the
            Registrant
   10.9*+  License Agreement, dated May 26, 1994, between CMCC and the Registrant
  10.10*+  Amendment to License Agreement, dated August 23, 1995, between CMCC and the
            Registrant
   10.11*  Sponsored Research Agreement, dated November 5, 1992, between the Registrant and
            CBR Laboratories, Inc. ("CBRL")
  10.12*+  Licensing Agreement, dated November 5, 1992, between the Registrant and CBRL
   10.13*  Employment Agreement, dated as of January 1, 1996, between the Registrant and John
            W. Holaday, Ph.D.
   10.14*  1992 Stock Incentive Plan
   10.15*  Amended and Restated 1996 Stock Option Plan
   10.16*  Form of Stock Option Agreement
</TABLE>
    
 
                                      II-3
<PAGE>
   
<TABLE>
<C>        <S>
   10.17*  Consulting Agreement between the Registrant and Samuel R. Dunlap, Jr.
   10.18*  Consulting Agreement between the Registrant and Steve Gorlin (superseded by
            Exhibit 10.18a)
  10.18(a)* Termination Agreement dated May 15, 1996 effective August 1, 1996, between the
            Registrant and Steve Gorlin
   10.19*  Master Equipment Lease Agreement, dated April 10, 1995, between the Registrant and
            MMC/GATX Partnership No. 1
   10.20*  Lease between the Registrant and Red Gate III Limited Partnership
   10.21*  Form of Indemnification Agreement
   10.22*  Research and License Agreement, dated August 1993, between the Registrant and
            Innovative Therapeutics, Inc.
   11.1    Computation of per share data
   23.1    Consent of Bachner, Tally, Polevoy & Misher LLP (Exhibit 5.1)
   23.2    Consent of Ernst & Young LLP
   23.3*   Consent of Jones & Askew
   23.4*   Consent of Arnold & Porter
   24.1*   Power of Attorney
</TABLE>
    
 
- ------------------------
   
 *  Previously filed.
    
 +  Confidential treatment has been requested.
 
ITEM 17.  UNDERTAKINGS
 
    UNDERTAKINGS REQUIRED BY REGULATION S-K, ITEM 512(F).
    The undersigned registrant hereby undertakes  to provide to the  Underwriter
at  the closing  specified in  the Underwriting  Agreement certificates  in such
denominations and registered  in such names  as required by  the Underwriter  to
permit prompt delivery to each purchaser.
 
    UNDERTAKING REQUIRED BY REGULATION S-K, ITEM 512(H).
 
    Insofar  as indemnification for liabilities arising under the Securities Act
of 1933 may be  permitted to directors, officers  or controlling persons of  the
registrant  pursuant to the  foregoing provisions, 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 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 Act and will be governed by the final adjudication of
such issue.
 
    UNDERTAKINGS REQUIRED BY REGULATION S-K, ITEM 512(I).
 
    The undersigned registrant hereby undertakes that:
 
    (1)For  purposes of  determining any liability  under the  Securities Act of
       1933, as amended,  the information  omitted from the  form of  prospectus
filed  as part  of this  Registration Statement in  reliance upon  Rule 430A and
contained in the  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.
 
    (2)For purposes 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-4
<PAGE>
                                   SIGNATURES
 
   
    Pursuant  to the requirements of the  Securities Act of 1933, the registrant
has duly caused  this amendment to  Registration Statement to  be signed on  its
behalf  by the undersigned, thereunto duly authorized, in the City of Rockville,
State of Maryland on the 6th day of June, 1996.
    
 
                                          ENTREMED, INC.
 
                                          By:     /s/ JOHN W. HOLADAY, PH.D.
 
                                             -----------------------------------
                                             John W. Holaday, Ph.D., Chairman of
                                                             the
                                              Board and Chief Executive Officer
 
   
                                   SIGNATURE
    
 
   
    Pursuant to the requirements of the  Securities Act of 1933, this  amendment
to  Registration  Statement has  been  signed by  the  following persons  in the
capacities and on the dates indicated.
    
 
   
<TABLE>
<C>                                                     <S>                                     <C>
                      SIGNATURE                                         TITLE                         DATE
- ------------------------------------------------------  --------------------------------------  -----------------
              /s/ JOHN W. HOLADAY, PH.D.                Chairman of the Board and Chief
     -------------------------------------------         Executive Officer (principal             June 6, 1996
                John W. Holaday, Ph.D.                   executive officer)
 
                  /s/ JOHN C. THOMAS
     -------------------------------------------        Chief Financial Officer (principal        June 6, 1996
                    John C. Thomas                       accounting and financial officer)
 
                /s/ CARL ALVING, M.D.
     -------------------------------------------        Director                                  June 6, 1996
                  Carl Alving, M.D.
 
                 /s/ DONALD S. BROOKS
     -------------------------------------------        Director                                  June 6, 1996
                   Donald S. Brooks
 
                /s/ BART CHERNOW, M.D.
     -------------------------------------------        Director                                  June 6, 1996
                  Bart Chernow, M.D.
 
     -------------------------------------------        Executive Advisor and Director               , 1996
                Samuel R. Dunlap, Jr.
 
                /s/ MARK C.M. RANDALL
     -------------------------------------------        Director                                  June 6, 1996
                  Mark C.M. Randall
 
             /s/ LEON E. ROSENBERG, M.D.
     -------------------------------------------        Director                                  June 6, 1996
               Leon E. Rosenberg, M.D.
 
                /s/ WENDELL M. STARKE
     -------------------------------------------        Director                                  June 6, 1996
                  Wendell M. Starke
</TABLE>
    
 
                                      II-5
<PAGE>
                                                                    EXHIBIT 11.1
 
                                 ENTREMED, INC.
                     COMPUTATION OF EARNINGS PER SHARE (1)
 
   
<TABLE>
<CAPTION>
                                                                                YEAR ENDED
                                                                               DECEMBER 31,
                                                                              --------------
                                                                                   1995
                                                                              --------------   THREE MONTH
                                                                                               PERIOD ENDED
                                                                                                MARCH 31,
                                                                                              --------------
                                                                                                   1996
                                                                                              --------------
                                                                                               (UNAUDITED)
<S>                                                                           <C>             <C>
Weighted average common and common equivalent shares outstanding during the
 period.....................................................................       5,485,763       6,438,017
Effect of common stock issued and stock options and warrants granted
 subsequent to April 12, 1995 computed in accordance with the treasury stock
 method as required by the SEC (2)..........................................       1,786,180         874,018
Conversion of preferred stock (3)...........................................       2,000,000       2,000,000
                                                                              --------------  --------------
Pro forma weighted average number of shares outstanding (3).................       9,271,943       9,312,035
                                                                              --------------  --------------
                                                                              --------------  --------------
Pro forma net loss per share (3)............................................  $        (0.83) $        (0.18)
                                                                              --------------  --------------
                                                                              --------------  --------------
</TABLE>
    
 
- ------------------------------
(1)  All  share information has been adjusted to reflect a two-for-three reverse
     stock split.
 
(2)  Pursuant to Securities  and Exchange Commission  Staff Accounting  Bulletin
     No.  83, Common and  Preferred Stock issued and  stock options and warrants
     grants at prices below the assumed initial public offering price of  $15.00
     per  share  during the  12-month period  immediately preceding  the initial
     filing date of the Company's Registration Statement for its initial  public
     offering  have been included as outstanding for all periods presented using
     the treasury stock method.
 
   
(3)  Pro forma net loss  per share and weighted  average shares outstanding  for
     the year ended December 31, 1995 and the three month period ended March 31,
     1996  give  effect to  the  automatic conversion  of  3,000,000 outstanding
     shares of Preferred Stock into 2,000,000 shares of Common Stock on the date
     of this Prospectus.
    

<PAGE>
                                                                     EXHIBIT 1.1
 
                                                                 DRAFT OF 6/6/96
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
 
                                3,200,000 SHARES
                                 ENTREMED, INC.
                                  COMMON STOCK
 
                               ------------------
 
                             UNDERWRITING AGREEMENT
                           SELECTED DEALER AGREEMENT
 
                               ------------------
 
                                 JUNE   , 1996
 
- --------------------------------------------------------------------------------
- --------------------------------------------------------------------------------
<PAGE>
                                3,200,000 SHARES
                                 ENTREMED, INC.
                                  COMMON STOCK
 
                        --------------------------------
                             UNDERWRITING AGREEMENT
                         -----------------------------
 
                                                                   June   , 1996
ALLEN & COMPANY INCORPORATED
DILLON, READ & CO. INC.
VOLPE, WELTY & COMPANY
  As Representatives of the Several Underwriters
  c/o Allen & Company Incorporated
711 Fifth Avenue
New York, New York 10022
 
Dear Sirs:
 
    EntreMed,  Inc., a Delaware corporation (the "Company"), hereby confirms its
agreement with  the  several  Underwriters  named  in  schedule  A  hereto  (the
"Underwriters"),   for   which   you   are   acting   as   representatives  (the
"Representatives"), as follows:
 
    1.  DESCRIPTION OF  SECURITIES.  The Company  has authorized by  appropriate
corporate  action and proposes to issue and  sell to the Underwriters its shares
of Common  Stock, $.01  par value.  As further  described in  Section 3  hereof,
3,200,000  of such shares (the "Purchased Shares") are being sold by the Company
to the Underwriters and the Company is granting to the Underwriters an option to
purchase up to 480,000  additional shares (the  "Option Shares"). The  Purchased
Shares and Option Shares are herein collectively referred to as the "Shares".
 
    2.   REPRESENTATIONS, WARRANTIES AND AGREEMENTS OF THE COMPANY.  The Company
represents and warrants to and agrees with each Underwriter that:
 
         (a)
       A registration statement on Form S-1 (File No. 333-3536) with respect  to
       the  Shares, including a preliminary form  of prospectus, copies of which
have heretofore  been delivered  to you,  has been  prepared by  the Company  in
conformity  with the requirements of the Securities Act of 1933, as amended (the
"Act"), and  the rules  and regulations  (the "Rules  and Regulations")  of  the
Securities  and Exchange  Commission (the "Commission")  under the  Act, and has
been filed with the  Commission under the Act;  such amendment or amendments  to
such  registration statement, copies of which  have heretofore been delivered to
you, as may  have been made  prior to the  date of this  Agreement have been  so
prepared and filed; and the Company has so prepared and proposes so to file in a
timely  manner after the effective date of such registration statement the final
form  of  prospectus.  Such  registration  statement  (including  all   exhibits
thereto),  as finally amended and revised as  of the time the Underwriters first
offer the Shares for sale to the public together with information, if any, which
is permitted to  be, and is,  subsequently filed  pursuant to Rule  430A of  the
Rules  and Regulations, is  herein referred to  as the "Registration Statement".
Such prospectus in  the form  filed pursuant  to Rule  424(b) of  the Rules  and
Regulations, or, if no final prospectus is filed with the Commission pursuant to
Rule  424(b),  in  such  form  as  such  final  prospectus  is  included  in the
Registration  Statement,  is  herein  referred  to  as  the  "Prospectus".  Each
preliminary  form  of  prospectus  is  herein  referred  to  as  a  "Preliminary
Prospectus".
 
         (b)
       The Commission has not issued any order preventing or suspending the  use
       of  any Preliminary Prospectus. At the time of filing of each Preliminary
Prospectus, such prospectus did not include
<PAGE>
any untrue statement  of a  material fact  or omit  to state  any material  fact
necessary  to make the  statements therein, in light  of the circumstances under
which they  were  made, not  misleading.  When the  Registration  Statement  was
declared effective and at all times subsequent thereto up to and at each Closing
Date  (hereinafter defined) (i)  the Registration Statement did  and will in all
material respects  conform to  the requirements  of the  Act and  the Rules  and
Regulations,  and (ii) the Registration Statement did not or will not include as
of its  date any  untrue statement  of  a material  fact or  omit to  state  any
material  fact necessary to make the statements therein not misleading. When the
Prospectus or any amendment or supplement  thereto is filed with the  Commission
pursuant  to Rule 424(b) (or, if the  Prospectus or such amendment or supplement
is not required to be so filed, when the Registration Statement or the amendment
thereto containing such  amendment or  supplement to  the Prospectus  was or  is
declared  effective), on  the date when  the Prospectus is  otherwise amended or
supplemented and on each Closing Date (as hereinafter defined), the  Prospectus,
as  amended or supplemented at any such time, (i) complied or will comply in all
material respects with the requirements of the Act and the Rules and Regulations
and (ii) did not or will not include any untrue statement of a material fact  or
omit  to  state any  material fact  necessary  in order  to make  the statements
therein, in  the light  of the  circumstances under  which they  were made,  not
misleading.  The  foregoing representations  and warranties  shall not  apply to
information contained  in or  omitted  from the  Registration Statement  or  the
Prospectus  or  any  such  amendment  or supplement  in  reliance  upon,  and in
conformity with, written information furnished to the Company by or on behalf of
any Underwriter for use in the preparation thereof.
 
         (c)
       Except as described in or  contemplated by the Prospectus (including  the
       disclosure contained therein regarding the Company's continued incurrence
of  losses and working capital decreases), subsequent to the respective dates as
of which information is given in the Registration Statement and the  Prospectus,
the  Company  has not  incurred  any direct  or, to  the  best of  the Company's
knowledge, contingent material liabilities  or material obligations, or  entered
into  any  material transactions  or  contracts not  in  the ordinary  course of
business, and there  has not  been any material  change in  its capital  shares,
options or warrants, nor any material increase or decrease in the amount thereof
outstanding  or in any of its long-term debt outstanding, except pursuant to the
terms of the instruments governing the  same, or any material adverse change  in
the  condition  (financial or  otherwise),  results of  operations,  business or
prospects of the Company.
 
         (d)
       Except as set forth in  the Prospectus, there is  not now pending or,  to
       the  knowledge of the Company, threatened, any action, suit or proceeding
to which the Company is a party  before any court or governmental or  regulatory
agency  or body  which could  reasonably be expected  to result  in any material
adverse change in the condition (financial or otherwise), results of operations,
business or  prospects  of the  Company,  or  could reasonably  be  expected  to
materially and adversely affect the properties, assets or ability to do business
as  contemplated in the Prospectus of the Company; and there are no contracts or
documents required to be filed as exhibits to the Registration Statement by  the
Act or by the Rules and Regulations which have not been filed as exhibits to the
Registration Statement.
 
         (e)
       This Agreement has been duly authorized, executed and delivered on behalf
       of  the  Company and  constitutes a  valid and  binding agreement  of the
Company, enforceable  in  accordance  with  its  terms,  except  (1)  that  such
enforcement may be subject to bankruptcy, insolvency, reorganization, moratorium
or  other similar laws now or hereafter  in effect relating to creditors' rights
and (2)  as rights  to indemnity  or contribution  hereunder may  be limited  by
federal  or state  securities laws; the  execution, delivery  and performance of
this Agreement and the consummation of the transactions herein contemplated will
not result in a breach or violation of any term or provision of, or constitute a
default under, (i) any currently existing statute, any indenture, mortgage, deed
of trust, note agreement or other agreement or instrument filed as an exhibit to
the Registration Statement or  any other material  indenture, mortgage, deed  of
trust,    note   or   agreement   or    other   agreement   or   instrument   to
 
                                       2
<PAGE>
which the Company is a party or by  which it or its property is bound; (ii)  the
charter or by-laws of the Company; or (iii) any order, rule or regulation of any
court  or governmental  agency or body  having jurisdiction over  the Company or
over its properties, which breach, violation or default of any such order,  rule
or  regulation could  reasonably be expected  to result in  any material adverse
change in  the condition  (financial  or otherwise),  results of  operations  or
business  of the  Company; no consent,  approval, authorization or  order of any
court or governmental  agency or body  is required for  the consummation by  the
Company of the transactions on its part herein contemplated, except such as have
been  obtained or such  as may be required  under the Act or  as may be required
under state or other securities or blue sky laws in connection with the purchase
and distribution of the Shares  by the Underwriters; and  the Company is not  in
material  default, and no event has occurred  which with the giving of notice or
lapse of  time  or both  would  be a  default,  under any  contract,  agreement,
indenture,  mortgage or other  undertaking to which  the Company is  a party and
which is  material  to  the  condition  (financial  or  otherwise),  results  of
operations, business or prospects of the Company.
 
         (f)
       The  Company  has been  duly incorporated  and is  validly existing  as a
       corporation in good standing  under the laws of  the jurisdiction of  its
incorporation, with full power and authority, corporate or otherwise, to own its
properties  and  conduct  its  business as  described  and  contemplated  in the
Registration Statement,  and is  duly  qualified to  do  business as  a  foreign
corporation  in good standing in all other jurisdictions where its operations or
ownership of property requires such  qualifications, except where failure so  to
qualify would not have a material effect on the Company.
 
         (g)
       The Company has the authorized and outstanding capital stock set forth in
       the  Prospectus; the outstanding  capital stock of  the Company conforms,
and the Shares when issued and sold as herein contemplated will conform, in  all
material  respects,  to  all statements  in  relation thereto  contained  in the
Registration Statement  and the  Prospectus and  all such  stock has  been  duly
authorized  and  the outstanding  capital stock  has been  and the  Shares, when
issued and  delivered  against payment  therefor  as provided  herein,  will  be
validly   issued,  fully-paid  and  nonassessable;   except  as  stated  in  the
Prospectus, the  stockholders of  the  Company have  no preemptive  rights  with
respect  to the Shares and there are  no outstanding rights, options or warrants
to acquire any securities of the Company; to the extent that any rights, options
or warrants to acquire any securities of the Company are outstanding, except  as
otherwise  set forth in the Prospectus, the  issuance of the Shares as described
in the Prospectus  will not result  in an  adjustment of the  exercise price  or
number  of shares  issuable upon  the exercise  in respect  of any  such rights,
options or warrants; and, except as  otherwise set forth in the Prospectus,  the
Company does not own (directly or indirectly) any shares of capital stock of any
subsidiaries.
 
         (h)
       Except  as  otherwise  set forth  in  the Prospectus,  the  Company owns,
       possesses or has rights to, or can acquire on reasonable terms,  adequate
patents,  patent applications,  patent licenses,  trademarks, service  marks and
trade names  necessary to  carry on  its business  as presently  conducted,  and
except  as set forth in the Prospectus,  the Company has not received any notice
of infringement of or  conflict with asserted rights  of others with respect  to
any  patents, patent licenses,  trademarks, service marks  or trade names which,
singly or in the aggregate, if the subject of an unfavorable decision, ruling or
finding, could  materially  and adversely  affect  the condition  (financial  or
otherwise), earnings, affairs, business or prospects of the Company.
 
         (i)
       Except as set forth in the Prospectus, the Company holds in good standing
       or  has applied  for all  licenses, permits,  authorizations, franchises,
consents and  orders of  all  federal, state,  local, and  foreign  governmental
bodies  that are material to the conduct  of its business as presently conducted
as described in the Prospectus; except as stated in the Prospectus, the  Company
has  good and marketable title  in fee simple to all  real property, if any, and
good and marketable title  to all personal  property owned by  it, in each  case
free  and clear of all  liens, encumbrances and defects  with such exceptions as
are not material  to the Company  taken as a  whole; and the  real property  and
personal  property referred  to in  the Prospectus  as held  under lease  by the
Company is held by it under valid, subsisting
 
                                       3
<PAGE>
and enforceable  leases with  only such  exceptions as  are referred  to in  the
Prospectus  or  as in  the  aggregate are  not material  to  the conduct  of its
business as presently conducted as described in the Prospectus.
 
         (j)
       The Company is conducting and proposes  to conduct its business so as  to
       comply  in all  material respects  with all  material applicable federal,
state, local  and  foreign governmental  statutes,  rules and  regulations;  and
except  as set forth in  the Prospectus, the Company is  not charged with, or to
the Company's knowledge, is under  investigation with respect to, any  violation
of any of such statutes, rules or regulations.
 
         (k)
       The Company is insured by insurers of recognized financial responsibility
       against  such losses  and risks  and in such  amounts as  are prudent and
customary in the business in which it is engaged; and, the Company does not have
any reason to believe that it will  not be able to renew its existing  insurance
coverage  as and when such  coverage expires or to  obtain similar coverage from
similar insurers as may  be necessary to  continue its business  at a cost  that
would not materially and adversely affect the business or financial condition of
the Company, except as described or contemplated in the Prospectus.
 
         (l)
       Ernst  &  Young LLP,  which  has examined  and  expressed its  opinion on
       certain of  the  financial  statements  of the  Company  filed  with  the
Commission  as a part of the Registration  Statement, are, to the Company's best
knowledge, independent  accountants  with  respect to  the  Company  within  the
meaning  of the  Act and  the Rules  and Regulations;  the financial statements,
together with the related notes, forming part of the Registration Statement  and
Prospectus fairly present the financial condition of the Company and its results
of  operations as of the dates and for  the periods described in such opinion in
the Prospectus; and such financial  statements have been prepared in  accordance
with the Rules and Regulations of the Commission.
 
         (m)
       The Company maintains a system of internal accounting controls sufficient
       to  provide  reasonable  assurances  that  transactions  are  executed in
accordance with management's general or specific authorizations and are recorded
as necessary to permit  preparation of financial  statements in conformity  with
generally accepted accounting principles.
 
         (n)
       Except  as stated in the Prospectus,  the Company knows of no outstanding
       claims  for  services,  either  in  the  nature  of  a  finder's  fee  or
origination  fee, with respect to the  transactions contemplated hereby, and the
Company agrees to  indemnify and hold  the Underwriters harmless  from any  such
claim  for any such services  of such nature arising from  the act of any person
other than any Underwriter or person acting on behalf of any Underwriter.
 
         (o)
       No person holds  a right to  require or participate  in the  registration
       under  the Act of the  Common Stock of the Company  to be effected by the
Registration Statement,  which right  has  not been  effectively waived  by  the
holder thereof as of the date hereof.
 
         (p)
       The  Company has  obtained from each  of its officers  and directors, and
       from each of its shareholders owning  an aggregate of          shares  of
the  Company's  Common  Stock  outstanding  immediately  prior  to  the offering
contemplated hereby, an executed agreement in form and substance satisfactory to
the Representatives that  they will not,  without the prior  written consent  of
Allen  & Company  Incorporated on  behalf of  the Underwriters,  sell, offer for
sale, contract  to sell  or otherwise  dispose of  any shares  of the  Company's
Common  Stock or any  securities exercisable for or  convertible into its Common
Stock or any rights to  acquire Common Stock for a  period of 180 days from  the
date of the final Prospectus.
 
    3.    PURCHASE,  SALE  AND  DELIVERY  OF  SHARES.    On  the  basis  of  the
representations, warranties and agreements herein contained, but subject to  the
terms and conditions herein set forth, the Company
 
                                       4
<PAGE>
agrees  to sell to  each Underwriter and each  Underwriter agrees, severally and
not jointly, to  purchase from the  Company, at  a purchase price  of $      per
Share,  the number of Shares set forth  opposite the name of such Underwriter in
Schedule A hereto.
 
    The Company will deliver the Purchased Shares to you for the accounts of the
several Underwriters at the  office of Allen &  Company Incorporated, 711  Fifth
Avenue,  New York, New York,  against payment of the  purchase price therefor by
certified or official  bank check or  checks in New  York Clearing House  funds,
payable  to  the order  of  EntreMed, Inc.,  at 10:00  A.M.,  New York  Time, on
            , 1996 or  at such  other time  and date  not later  than five  full
business  days thereafter as  you and the  Company may determine,  such time and
date of delivery and payment being  herein called the "First Closing Date".  The
certificates  for the Purchased Shares to be so delivered will be made available
to you at such office for checking at least one full business day prior to  such
Closing  Date and will be in such names  and denominations as you may request in
writing not less than two full business days prior to such Closing Date.
 
    On the  basis  of  the representations,  warranties  and  agreements  herein
contained, but subject to the terms and conditions herein set forth, the Company
grants  to the Underwriters an option to purchase up to 480,000 Option Shares at
the same price per share as the Underwriters shall pay for the Purchased Shares.
Such option may be exercised only to cover over-allotments arising in connection
with the sale of Purchased Shares by the Underwriters, such exercise to be  upon
written  notice by you to the Company within  30 days of the date hereof setting
forth the number of Options Shares  as to which the Underwriters are  exercising
the  option, the denominations  and names in which  certificates for such Shares
should be registered and the time and place at which such certificates are to be
delivered. Such time  and place (unless  such time is  the First Closing  Date),
herein  referred to as the "Second Closing Date", shall be determined by you but
shall not be earlier than  the First Closing Date,  nor earlier than three  full
business  days or later than  ten full business days  after the exercise of such
option. The Company will deliver  Option Shares to you  for the accounts of  the
several Underwriters against payment of the purchase price therefor by certified
or official bank check or checks in New York Clearing House funds payable to the
order  of EntreMed,  Inc. The number  of Option  Shares to be  purchased by each
Underwriter shall be in  the same proportion to  the aggregate number of  Option
Shares  purchased as the number of Purchased  Shares set forth opposite the name
of such Underwriter in Schedule A hereto bears to 3,200,000.
 
    It is understood that  you, individually and not  as the Representatives  of
the  several Underwriters, may (but  shall not be obligated  to) make payment on
behalf of any  Underwriter or Underwriters  for Shares to  be purchased by  such
Underwriter  or Underwriters. Any such payment by you shall not relieve any such
Underwriter or Underwriters of any of its or their obligations hereunder.
 
    After the Registration Statement becomes effective, the several Underwriters
propose to offer the Shares to the public as set forth in the Prospectus.
 
    4.  COVENANTS OF  THE COMPANY.   The Company covenants  and agrees with  the
several Underwriters that:
 
         (a)
       The Company will use its best efforts to cause the Registration Statement
       and  any subsequent amendment thereto to  become effective as promptly as
possible; it will notify you, promptly after it shall receive notice thereof, of
the time when  the Registration  Statement or  any subsequent  amendment to  the
Registration  Statement has become effective or any supplement to the Prospectus
has been filed; it will notify you promptly of any request by the Commission for
the amending or supplementing of the Registration Statement or Prospectus or for
additional information;  it  will  prepare  and file  with  the  Commission  any
amendments  or supplements to the Registration Statement or Prospectus which, in
your reasonable opinion or the reasonable opinion of the Company or its counsel,
may be  necessary in  connection with  the  distribution of  the Shares  by  the
Underwriters;  it  will  promptly  prepare and  file  with  the  Commission, and
promptly notify you of the filing of, any
 
                                       5
<PAGE>
amendments or supplements to the Registration Statement or Prospectus which  may
be  necessary to  correct any statements  or omissions,  if, at any  time when a
prospectus relating to the Shares is required to be delivered under the Act, any
event shall have occurred as a result  of which the Prospectus would include  an
untrue statement of a material fact or omit to state any material fact necessary
to  make the statements therein, in light  of the circumstances under which they
were made, not  misleading; in  case any Underwriter  is required  to deliver  a
prospectus  after the nine-month  period referred to in  Section 10(a)(3) of the
Act in connection with  sales of the Shares  purchased by the Underwriters  from
the  Company pursuant  to Section  3 or  otherwise acquired  by the Underwriters
during the  distribution  of the  Shares  in connection  with  stabilization  or
otherwise,  the Company will prepare and  file with the Commission promptly upon
request of,  but  at  the  expense  of,  such  Underwriter,  any  amendments  or
supplements  to the Registration Statement or Prospectus as may be necessary, in
such Underwriter's reasonable opinion, to permit the sale of such Shares in  the
manner  determined by such  Underwriter, in compliance  with the requirements of
the Act, including Section 10(a)(3) thereunder; and it will file no amendment or
supplement to the Registration Statement or Prospectus that shall not previously
have been submitted to you  in writing a reasonable  time prior to the  proposed
filing thereof or to which you shall reasonably object in writing, except as may
be required by law.
 
         (b)
       The  Company will advise  you, promptly after it  shall receive notice or
       obtain knowledge thereof, of the issuance  by the Commission of any  stop
order suspending the effectiveness of the Registration Statement or of any order
suspending  trading in the Shares or other of the Company's securities or of the
initiation or  threat  of any  proceeding  for that  purpose;  and it  will  use
promptly its best efforts to prevent the issuance of any stop order or to obtain
its withdrawal if such a stop order should be issued.
 
         (c)
       The  Company will  use its  best efforts to  qualify the  Shares for sale
       under the blue sky  or securities laws of  such jurisdictions as you  may
reasonably  designate and to continue such  qualifications in effect for so long
as may be required for purposes of  the distribution of the Shares, except  that
the  Company shall  not be  required in connection  therewith or  as a condition
thereof to qualify as a foreign corporation  or to execute a general consent  to
service of process in any state.
 
         (d)
       The  Company will  furnish to  you, as soon  as available,  copies of the
       Registration Statement (one of which will be signed and will include  all
exhibits),  each Preliminary Prospectus,  the Prospectus, and  any amendments or
supplements to  such  documents, including  any  prospectus prepared  to  permit
compliance  with Section 10(a)(3) of the Act,  all in such quantities as you may
from time to time reasonably request.
 
         (e)
       The Company will make generally available to its security holders as soon
       as practicable, an earnings statement (which will be in reasonable detail
but need  not  be  audited)  covering a  12-month  period  beginning  after  the
effective  date of the Registration Statement which shall satisfy the provisions
of Section 11(a) of the Act.
 
         (f)
       The Company agrees, during  each fiscal year for  a period of five  years
       from  the date hereof, to furnish to  its stockholders as promptly as may
be practicable  an  annual report  (including  financial statements  audited  by
independent  public accountants)  and to publish  quarterly financial statements
(which need not be audited) for each of the first three quarters of each  fiscal
year, and to furnish, upon request, to each Underwriter hereunder (i) as soon as
practicable  after the end  of each of  the first three  quarters of each fiscal
year, the Company's quarterly report on  Form 10-Q; (ii) as soon as  practicable
after the end of each fiscal year, financial statements of the Company as at the
end  of such fiscal year, including  statements of operations, retained earnings
and changes in cash flow of the Company for such fiscal year, all in  reasonable
detail  and accompanied by  a copy of  the report thereon  of independent public
accountants or the Company's annual  report on Form 10-K;  and (iii) as soon  as
they  are available, copies  of all reports and  financial statements filed with
the Commission. During
 
                                       6
<PAGE>
such period, if and so long as  the Company shall have active subsidiaries,  the
foregoing  financial statements shall be on  a combined or consolidated basis to
the extent that the accounts of the Company and its subsidiaries are combined or
consolidated.
 
         (g)
       The Company covenants and agrees  with the several Underwriters that  the
       Company  will  pay or  cause  to be  paid  the following:  (i)  the fees,
disbursements,  and  expenses  of  the  Company's  counsel  and  accountants  in
connection  with the registration  of the Shares  under the Act;  (ii) all other
expenses in  connection  with  the  preparation, printing,  and  filing  of  the
Registration  Statement,  each Preliminary  Prospectus,  and the  Prospectus and
amendments and supplements  thereto, and  the mailing and  delivering of  copies
thereof  to  the  Underwriters and  dealers;  (iii)  the cost  of  printing this
Agreement, the Selected Dealer Agreement, the Blue Sky Memorandum, and any other
documents in connection with  the offering, purchase, sale  and delivery of  the
Shares; (iv) all costs and expenses in connection with the issuance and delivery
of  the Shares hereunder to the  Underwriters, including related transfer taxes,
if any; (v) all expenses in connection with the qualification of the Shares  for
offering  and sale under the securities laws of various jurisdictions, including
the fees and disbursements  of counsel for the  Underwriters in connection  with
such  qualification and in connection with the  Blue Sky Survey; (vi) the filing
fees incident to  securing any required  review by the  National Association  of
Securities Dealers, Inc. of the terms of the sale of the Shares; (vii) the costs
of  preparing stock  certificates; (viii) the  cost and charges  of any transfer
agent or  registrar; and  (ix) all  other  costs and  expenses incident  to  the
performance  of its obligations  hereunder which are  not otherwise specifically
provided for in this Section 4. In addition to the foregoing, the Company  shall
reimburse the Underwriters, upon request from time to time, for their reasonable
itemized  out-of-pocket expenses  up to a  maximum of  $200,000, including their
reasonable legal  fees  and disbursements  and  travel, roadshow  and  syndicate
expenses,  upon  the presentation  of reasonable  documentation thereof.  If the
Company determines not to proceed with  the offering for any reason, other  than
the Underwriters' unwillingness to proceed on the terms and conditions set forth
in  this Agreement, or if the  Representatives exercise their right to terminate
this Agreement pursuant to Section 10(b)(i) hereof, the Company shall  reimburse
the  Underwriters for all reasonable out-of-pocket expenses including reasonable
legal fees  and  disbursements  and  travel,  roadshow  and  syndicate  expenses
actually  incurred  by the  Underwriters,  upon the  presentation  of reasonable
documentation thereof, up to a maximum of $300,000. The Company shall not in any
event be liable to any of the  Underwriters for the loss of anticipated  profits
from the transactions covered by this Agreement.
 
         (h)
       The Company agrees that it will not, without the prior written consent of
       the  Allen &  Company Incorporated on  behalf of  the Underwriters, sell,
offer for sale,  contract to  sell or  otherwise dispose  of any  shares of  its
Common Stock or any securities exercisable for or convertible into shares of its
Common  Stock or any  rights to acquire Common  Stock, for a  period of 180 days
after the date of the final  Prospectus, otherwise than in accordance with  this
Agreement  or as contemplated in the  Prospectus; PROVIDED, that the Company may
issue Common Stock,  or options, rights  or warrants with  respect thereto,  (i)
upon  the exercise of stock options and warrants outstanding on the date hereof,
(ii) pursuant to stock option plans of the Company existing on the date  hereof,
to  persons who have  received, or who  are eligible to  receive, grants of such
options and (iii) not to exceed, in the aggregate, 10% of the outstanding shares
of Common Stock as of  the First Closing Date, in  connection with any new  bona
fide  research, licensing  or corporate  partnering relationships  and equipment
lease transactions.
 
    5.  CONDITIONS OF UNDERWRITERS' OBLIGATIONS.  The obligations of the several
Underwriters to purchase and pay for  the Purchased Shares on the First  Closing
Date  and the Option Shares on the Second Closing Date, as provided herein shall
be subject to the accuracy, as of the  date hereof and such Closing Date (as  if
made  on and as of such Closing  Date), of the representations and warranties of
the Company  herein,  to the  performance  by  the Company  of  its  obligations
hereunder, and to the following additional conditions:
 
                                       7
<PAGE>
         (a)
       The  Registration Statement  shall have  become effective  not later than
       5:30 P.M., New York  City Time, on  the date of  this Agreement, or  such
later  date  as  shall be  consented  to in  writing  by you;  if  required, the
Prospectus and any amendment  or supplement thereto shall  have been filed  with
the  Commission in the manner and within the time period required by Rule 424(b)
under the Act; and no stop order suspending the effectiveness thereof shall have
been issued and no proceedings for that purpose shall have been initiated or, to
the knowledge of the Company or  any Underwriter, threatened by the  Commission,
and  any request of the Commission for additional information (to be included in
the Registration  Statement or  the  Prospectus or  otherwise) shall  have  been
complied with to your reasonable satisfaction.
 
         (b)
       Prior  to such  Closing Date, except  as contemplated  in the Prospectus,
       there shall  not have  been any  change in  the capital  shares, nor  the
issuance of any rights, options, or warrants to purchase any capital shares, nor
any  material increase or decrease  in any long-term debt  of the Company or any
material adverse change in  the condition (financial  or otherwise), results  of
operations,  business  or  prospects of  the  Company which  in  your reasonable
judgment renders it  inadvisable to proceed  with the offering  and sale of  the
Shares.
 
         (c)
       You  shall have received the opinion  of Bachner, Tally, Polevoy & Misher
       LLP, counsel for the Company, in  form and substance satisfactory to  you
and dated such Closing Date, to the effect that:
 
       (i) the  Company has been duly incorporated  and is validly existing as a
           corporation in good standing under the laws of the State of  Delaware
    with full corporate power and authority to own its properties and to conduct
    its  business  as  described  in  the  Registration  Statement  and  is duly
    qualified to do business  as a foreign corporation  in Maryland and in  each
    state  or  jurisdiction  where  its  operations  and  the  ownership  of its
    properties requires  such  qualification, except  where  the failure  to  so
    qualify  will not  have a  material adverse  effect on  the business  of the
    Company;
 
       (ii)the Company  has  authorized  capital  stock  as  set  forth  in  the
           Prospectus; all shares of Common Stock, including the Shares, conform
    as to legal matters in all material respects to the appropriate descriptions
    thereof  under the heading "Description of Capital Stock" in the Prospectus;
    all outstanding shares of  Company capital stock  have been duly  authorized
    and  are validly issued, fully paid  and non-assessable; and the issuance of
    the Shares has been duly authorized and, when issued, delivered and paid for
    in accordance with this Agreement, the Shares will be validly issued,  fully
    paid and non-assessable;
 
       (iii)
           this  Agreement has been  duly authorized, executed  and delivered by
           the Company  and constitutes  a valid  and binding  agreement of  the
    Company,  enforceable in  accordance with  its terms,  except that  (1) such
    enforcement  may  be  subject  to  bankruptcy,  insolvency,  reorganization,
    moratorium  or other  similar laws  now or  hereafter in  effect relating to
    creditors' rights and (2) rights to indemnity or contribution hereunder  may
    be   limited  by  federal  or  state  securities  laws  and  (3)  except  as
    enforceability  may  be  limited  by  equitable  principles  affecting   the
    availability  of remedies; the  sale of the Shares  under this Agreement and
    the consummation of the transactions herein contemplated do not result in  a
    breach  or violation of any material terms or provisions of, or constitute a
    material default under, any applicable statute, or any indenture,  mortgage,
    deed  of trust, note agreement or other  agreement or instrument filed as an
    exhibit to the Registration Statement or otherwise known to counsel to which
    the Company  is a  party or  by  which it  or its  properties are  bound  or
    affected,  or to which any of the material property or assets of the Company
    is subject, the Company's certificate  of incorporation and by-laws, or,  to
    the  best of such counsel's knowledge, any  order, rule or regulation of any
    court or governmental agency or body having jurisdiction over the Company or
    its properties;
 
       (iv)no  consent,  approval,  authorization  or  order  of  any  court  or
           governmental  agency or body is required  for the consummation by the
    Company of the transactions contemplated by this
 
                                       8
<PAGE>
    Agreement that has not been obtained,  except such as may be required  under
    the  Act or as  may be required under  state securities or  blue sky laws in
    connection  with  the  purchase  and  distribution  of  the  Shares  by  the
    Underwriters;
 
       (v) the Registration Statement has become effective under the Act and, to
           the  best of such  counsel's knowledge, no  stop order suspending the
    effectiveness  of  the  Registration  Statement  has  been  issued  and   no
    proceedings  for  that  purpose  have  been  instituted  or  are  pending or
    threatened under the Act;
 
       (vi)except as set forth in the  Prospectus and for such matters  referred
           to  in the paragraph next following subclause (xi) below, to the best
    of such counsel's knowledge, the Company holds in good standing all material
    licenses, permits,  authorizations,  franchises,  consents  and  orders,  of
    Federal,  State or local, and foreign governmental bodies necessary to carry
    on its business as reflected in the Registration Statement;
 
       (vii)
           the summaries of the agreements or documents to which the Company  is
           a  party included under  the headings "Business  -- Collaboration and
    License  Agreements,"  "Management   --  Employment  Agreements,"   "Certain
    Transactions"  and "Description of Capital  Stock -- Registration Rights" in
    the Prospectus fairly  summarize and  present in all  material respects  the
    information required to be presented therein;
 
       (viii)
           to  the best of such counsel's  knowledge after due inquiry (it being
           understood that for purposes  of this opinion,  due inquiry does  not
    include any search of court or administrative records), there is no legal or
    governmental  proceeding pending  or threatened  to which  the Company  is a
    party or  to  which any  properties  of the  Company  are subject  which  is
    required to be described in the Registration Statement or the Prospectus and
    is not so described;
 
       (ix)the  Registration Statement and the Prospectus, and each amendment or
           supplement thereto, as of their respective effective or issue  dates,
    comply  as to form in all material respects with the requirements of the Act
    and the Rules  and Regulations  (except that  such counsel  need express  no
    opinion  as  to the  financial  statements, notes  to  financial statements,
    related schedules or other financial data  contained in or omitted from  the
    Registration Statement or the Prospectus);
 
       (x) to  the  best  of such  counsel's  knowledge after  due  inquiry, all
           contracts and  documents pertaining  to the  Company required  to  be
    filed  as Exhibits to the Registration Statement have been filed as required
    and, to the best  of such counsel's knowledge,  all contracts and  documents
    required  to be described  in the Prospectus  have been accurately described
    therein in all material respects;
 
       (xi)Such counsel shall also state that it has participated in conferences
           with   officers   and   other   representatives   of   the   Company,
    representatives  of the independent  public accountants for  the Company and
    the representatives  of  the Underwriters,  at  which the  contents  of  the
    Registration Statement and the Prospectus and related matters were discussed
    and,  although such counsel did not independently verify, and is not passing
    upon and does not assume any responsibility for, the accuracy,  completeness
    or  fairness of the  statements contained in  the Registration Statement and
    the Prospectus, on the basis of the foregoing (relying as to materiality  to
    a  large extent upon  the opinions of officers  and other representatives of
    the Company), no facts have come to such counsel's attention which lead such
    counsel to believe that the  Registration Statement (except with respect  to
    the  financial  statements  and  schedules thereto  and  other  financial or
    statistical data, as to which such  counsel need not make any statement)  at
    the  time it became  effective contained any untrue  statement of a material
    fact or omitted to state  a material fact required  to be stated therein  or
    necessary  to  make  the  statements therein  not  misleading,  or  that the
    Prospectus (except with  respect to the  financial statements and  schedules
    thereto and other
 
                                       9
<PAGE>
    financial  or other statistical data, as to which such counsel need not make
    any statement) on  the date  thereof or on  the Closing  Date contained  any
    untrue  statement of  a material  fact or omitted  to state  a material fact
    necessary in  order to  make the  statements therein,  in the  light of  the
    circumstances in which they were made, not misleading.
 
    Such  counsel  need express  no opinion  as  to the  statements made  in the
Prospectus relating  to  patents  or proprietary  rights,  including  under  the
captions  "Risk Factors --  Dependence on Patents  and Other Proprietary Rights;
Uncertainty of Patent Position and Proprietary Rights" and "Business --  Patents
and  Proprietary  Rights"  or  statements made  in  the  Prospectus  relating to
government  regulatory  matters  concerning  the  development,  manufacture  and
potential sale of the Company's potential products, including under the captions
"Risk  Factors  -- Uncertainty  of  Government Regulatory  Requirements; Lengthy
Approval Process" and "Business -- Government Regulation."
 
    In rendering the  foregoing opinions, such  counsel may rely  as to  factual
matters  on certificates of  officers and representatives of  the Company and of
public officials, and will not be required to independently verify the  accuracy
or  completeness of information or  documents furnished to it  in respect to the
Registration Statement  or the  Prospectus. To  the extent  that such  counsel's
opinion  relates to the laws  of jurisdictions other than  New York or Delaware,
such counsel  shall  be  permitted to  rely  on  the opinion  of  local  counsel
reasonably satisfactory to counsel for the several Underwriters.
 
         (d)
       You  shall  have  received from  Jones  &  Askew, patent  counsel  to the
       Company, an  opinion, dated  such  Closing Date,  in form  and  substance
satisfactory  to you, to the effect that  the statements in the Prospectus under
the captions  "Risk  Factors --  Dependence  on Patents  and  Other  Proprietary
Rights;  Uncertainty of Patent Position and Proprietary Rights" and "Business --
Patents and  Proprietary Rights",  insofar  as they  pertain to  legal  matters,
fairly present in all material respects the information presented therein.
 
         (e)
       You  shall have received from Arnold  & Porter, regulatory counsel to the
       Company, an  opinion, dated  such  Closing Date,  in form  and  substance
satisfactory  to you, to the effect that  the statements in the Prospectus under
the captions "Risk Factors -- Uncertainty of Government Regulatory Requirements;
Lengthy Approval Process"  and "Business --  Government Regulation", insofar  as
they  pertain  to legal  matters, fairly  present in  all material  respects the
information presented therein.
 
         (f)
       You shall have received from Werbel McMillin & Carnelutti, A Professional
       Corporation,  counsel  for  the  several  Underwriters,  an  opinion   or
opinions,  dated such Closing  Date, in form and  substance satisfactory to you,
with respect to  the sufficiency  of all  such corporate  proceedings and  other
legal  matters  relating to  this  Agreement and  the  transactions contemplated
hereby as you may  reasonably require, and the  Company shall have furnished  to
such  counsel  such documents  as  they may  have  reasonably requested  for the
purpose of enabling them to pass upon such matters.
 
         (g)
       You shall have received, at the  time of execution of this Agreement  and
       on  such  Closing  Date  from  Ernst  &  Young  LLP,  independent  public
accountants,  a  letter  or  letters,  dated  the  date  of  delivery   thereof,
substantially in the form and substance heretofore approved by you.
 
         (h)
       You  shall have received a certificate,  dated such Closing Date, of each
       of the  President and  Chief Executive  Officer and  the Chief  Financial
Officer of the Company, delivered on behalf of the Company, to the effect that:
 
       (i) the  representations and warranties of  the Company in this Agreement
           are true and correct as if made  on and as of such Closing Date;  and
    the  Company  has complied  with all  the agreements  and satisfied  all the
    conditions on its  part to be  performed or  satisfied at or  prior to  such
    Closing Date;
 
                                       10
<PAGE>
       (ii)no  stop  order  suspending  the  effectiveness  of  the Registration
           Statement has been issued, and  no proceedings for that purpose  have
    been  instituted or, to their knowledge, are contemplated by the Commission;
    and
 
       (iii)
           except as  contemplated  in  the  Prospectus,  the  Company  has  not
           incurred  any  direct or,  to the  best  of the  Company's knowledge,
    contingent material liabilities or obligations, or entered into any material
    transactions or contracts not in the ordinary course of business, and  there
    has  not  been any  change in  the capital  shares of  the Company,  nor the
    issuance of any rights, options, or warrants to purchase any capital shares,
    nor any material  increase or decrease  in any thereof  or in any  long-term
    debt  or  any  material  adverse  change  in  the  condition  (financial  or
    otherwise) results of operations, business or prospects of the Company.
 
         (i)
       You shall have received  a certificate, dated such  Closing Date, of  the
       Chief  Financial  Officer  of the  Company,  delivered on  behalf  of the
Company, to the effect that, except as described in the Prospectus, the issuance
of the Shares as described in the  Prospectus will not result in any  adjustment
of  the exercise price or number of  shares issuable upon exercise in respect of
any outstanding options or warrants of the Company;
 
         (j)
       The Company shall have furnished to you such certificates, in addition to
       those  specifically  mentioned  herein,   as  you  may  have   reasonably
requested,  as to  the accuracy  and completeness  at such  Closing Date  of any
statement in the  Registration Statement or  Prospectus, as to  the accuracy  at
such  Closing Date of the representations  and warranties of the Company herein,
as to the performance by the Company of its obligations hereunder, and as to the
fulfillment of the conditions concurrent and precedent to the obligations of the
Underwriters hereunder.
 
         (k)
       The Company  shall have  furnished  to you  the agreements  described  in
       Section 2(p) of this Agreement.
 
         (l)
       The  Company shall have  effected a two-for-three  reverse stock split of
       its Common Stock and all issued  and outstanding shares of its  Preferred
Stock   shall  have  been  automatically   converted  into  Common  Stock,  each
transaction occurring as described in the Prospectus.
 
    6.  INDEMNIFICATION.  (a)  The Company will indemnify and hold harmless each
Underwriter and each  person, if any,  who controls any  Underwriter within  the
meaning of the Act, against any losses, claims, damages or liabilities, joint or
several,  to  which  such  Underwriter or  such  controlling  person  may become
subject, under the Act or otherwise, insofar as such losses, claims, damages  or
liabilities  (or actions in respect thereof) arise  out of or are based upon any
untrue statement or alleged untrue statement  of any material fact contained  in
the  Registration Statement, any Preliminary  Prospectus, the Prospectus, or any
amendment or supplement thereto, or arise out of or are based upon the  omission
or  alleged omission  to state  therein a  material fact  required to  be stated
therein or necessary to make the statements therein not misleading, and, subject
to Section  6(c), will  reimburse  each Underwriter  and each  such  controlling
person  for any legal or other  expenses reasonably incurred by such Underwriter
or such controlling person in connection with investigating or defending against
any such loss, claim, damage, liability  or action; provided, however, that  the
Company  will not be liable in  any such case to the  extent that any such loss,
claim, damage or liability arises out of  or is based upon any untrue  statement
or  alleged  untrue  statement  or  omission or  alleged  omission  made  in the
Registration Statement,  such Preliminary  Prospectus,  the Prospectus  or  such
amendment  or such  supplement in reliance  upon and in  conformity with written
information furnished to the Company by or on behalf of any Underwriter for  use
therein;  and provided  further, that  the foregoing  indemnity with  respect to
Preliminary Prospectuses shall not inure to  the benefit of any Underwriter  (or
to  the  benefit of  any  person controlling  such  Underwriter) if  such untrue
statement or  omission or  alleged  untrue statement  or  omission made  in  any
Preliminary Prospectus is eliminated or remedied in the Prospectus and a copy of
the  Prospectus has not been furnished to  the person asserting any such losses,
claims, damages, or liabilities at or  prior to the written confirmation of  the
sale of such Shares
 
                                       11
<PAGE>
to  such person. Such indemnity obligation will  be in addition to any liability
which the Company  may otherwise have.  The indemnity agreement  of the  Company
contained  in this paragraph  (a) and the representations  and warranties of the
Company contained in Section 2 hereof  shall remain operative and in full  force
and  effect  regardless  of  any  investigation made  by  or  on  behalf  of any
indemnified party and shall survive the delivery of and payment for the Shares.
 
         (b)
       Each Underwriter,  severally and  not jointly,  will indemnify  and  hold
       harmless  the Company,  each of its  directors, each of  its officers who
signed the Registration  Statement, and each  person, if any,  who controls  the
Company  within the meaning of  the Act, against any  losses, claims, damages or
liabilities, joint  or several,  to  which the  Company  or any  such  director,
officer  or controlling person  may become subject, under  the Act or otherwise,
insofar as such losses,  claims, damages or liabilities  (or actions in  respect
thereof)  arise out of or are based  upon any untrue statement or alleged untrue
statement of  any material  fact contained  in the  Registration Statement,  any
Preliminary  Prospectus, the Prospectus, or any amendment or supplement thereto,
or arise out  of or are  based upon the  omission or alleged  omission to  state
therein  a material fact required to be  stated therein or necessary to make the
statements therein not misleading, in each case  to the extent, but only to  the
extent,  that such untrue  statement or alleged untrue  statement or omission or
alleged omission  was made  in  reliance upon  and  in conformity  with  written
information  furnished to the Company by or on behalf of any Underwriter for use
therein; and,  subject  to Section  6(c),  will  reimburse any  legal  or  other
expenses  reasonably incurred  by the Company  or any such  director, officer or
controlling person in  connection with  investigating or  defending against  any
such loss, claim, damage, liability or action. Such indemnity obligation will be
in  addition to  any liability  which such  Underwriter may  otherwise have. The
indemnity agreement of each  Underwriter contained in  this paragraph (b)  shall
remain  operative and in  full force and effect  regardless of any investigation
made by or on behalf of any indemnified party and shall survive the delivery  of
and payment for the Shares.
 
         (c)
       Promptly  after receipt  by an  indemnified party  under this  Section of
       notice of the commencement of any action, such indemnified party will, if
a claim in respect thereof  is to be made  against the indemnifying party  under
this  Section,  notify  the  indemnifying  party  of  the  commencement thereof.
Indemnification shall not be available  to any party who  shall fail so to  give
notice,  if the party to whom notice was required to be given was unaware of the
action, suit, investigation,  inquiry or  proceeding to which  the notice  would
have  related, to the  extent that such  party was prejudiced  by the failure to
give notice;  but the  omission so  to notify  the indemnifying  party will  not
relieve  it  from any  liability  which it  may  have to  any  indemnified party
otherwise than under this  Section. In case any  such action is brought  against
any   indemnified  party,  and  it  notifies   the  indemnifying  party  of  the
commencement thereof, the  indemnifying party  will be  entitled to  participate
therein  and, to the extent that it may wish jointly with any other indemnifying
party similarly notified, to assume the defense thereof, with counsel chosen  by
such  indemnifying party  which is  reasonably satisfactory  to such indemnified
party, and after notice from the indemnifying party to such indemnified party of
its election so to assume the  defense thereof, the indemnifying party will  not
be  liable to such indemnified  party under this Section  for any legal or other
expenses subsequently incurred by such indemnified party in connection with  the
defense thereof other than reasonable costs of investigation; provided, however,
that  (i) if  the indemnified  party reasonably determines  that there  may be a
conflict between the positions of the indemnifying party and of the  indemnified
party  in conducting the defense of such action, suit, investigation, inquiry or
proceeding or that  there may be  legal defenses available  to such  indemnified
party  different  from or  in addition  to those  available to  the indemnifying
party, then counsel for the indemnified  party shall be entitled to conduct  the
defense  to the extent reasonably determined by  such counsel to be necessary to
protect the  interests of  the indemnified  party  and (ii)  in any  event,  the
indemnified  party (at its own expense) shall be entitled to have counsel chosen
by such indemnified party participate in, but not conduct, the defense (it being
understood, however, that in either such case, the indemnifying party shall not,
in connection with any one such action or separate but substantially similar  or
related  actions arising out  of the same  general allegations or circumstances,
 
                                       12
<PAGE>
be liable for the reasonable fees and expenses of more than one separate firm of
attorneys for the indemnified parties). No indemnifying party shall be liable to
any indemnified party in  respect to any settlement  effected without its  prior
written  consent, which consent shall not be unreasonably withheld. In addition,
the indemnifying  party  will not,  without  the  prior written  consent  of  an
indemnified   party,  which  shall  not  be  unreasonably  withheld,  settle  or
compromise or consent to the entry of any judgment in any pending or  threatened
claim,  action, suit  or proceeding in  respect of which  indemnification may be
sought hereunder  (whether or  not such  indemnified party  is a  party to  such
claim,  action or  suit or  proceeding), unless  such settlement,  compromise or
consent includes an  unconditional release  of such indemnified  party from  all
liability arising out of such claim, action, suit or proceeding.
 
    7.   CONTRIBUTION.  In order to provide for contribution in circumstances in
which the indemnification provided for in Section 6(a) or 6(b) hereof is for any
reason, other than the  first proviso to Section  6(a), held to be  unavailable,
the  Company  and the  Underwriters shall  contribute  to the  aggregate losses,
claims,  damages   and  liabilities   of  the   nature  contemplated   by   such
indemnification   provisions  (including  any  investigation,  legal  and  other
expenses incurred in  connection with,  any amount  paid in  settlement of,  any
action,  suit  or proceeding  or any  claims asserted,  but after  deducting any
contribution received by the Company  from persons other than the  Underwriters,
such  as persons who control the Company within the meaning of Section 15 of the
Act, officers of the Company who signed the Registration Statement and directors
of the Company, who may  also be liable for  contribution) to which the  Company
and  one or more of the Underwriters may be subject, in such proportions so that
the Underwriters are responsible  for that portion in  each case represented  by
the percentage that the respective underwriting discounts appearing on the cover
page  of the Prospectus bear to the public offering price of the Shares, and the
Company is responsible for  the remaining portion;  provided, however, that  (i)
except as may be provided in its Master Agreement Among Underwriters provided to
Allen  & Company Incorporated,  in no case shall  any Underwriter be responsible
for any amount in excess of  the underwriting discount applicable to the  Shares
purchased  by such Underwriter hereunder and (ii) no person guilty of fraudulent
misrepresentation (within the  meaning of  Section 11(f)  of the  Act) shall  be
entitled  to contribution from any person who  was not guilty of such fraudulent
misrepresentation. For purposes  of this  Section 7,  each person,  if any,  who
controls  an Underwriter within the meaning of  Section 15 of the Act shall have
the same rights to  contribution as such Underwriter,  and each person, if  any,
who  controls the  Company within  the meaning  of Section  15 of  the Act, each
officer of the Company who shall have signed the Registration Statement and each
director of  the  Company shall  have  the same  right  to contribution  as  the
Company,  subject in each  case to clauses (i)  and (ii) of  this Section 7. Any
party entitled  to  contribution  will,  promptly after  receipt  of  notice  of
commencement  of any action, suit or proceeding against such party in respect of
which a claim  for contribution  may be made  against another  party or  parties
under this Section 7, notify such party or parties from whom contribution may be
sought,  but the omission to  so notify such party  or parties shall not relieve
the party  or  parties from  whom  contribution may  be  sought from  any  other
obligation it or they may have hereunder or otherwise than under this Section 7.
No  party shall be liable  for contribution with respect  to any action or claim
settled without its consent, which consent shall not be unreasonably withheld.
 
    8.     REPRESENTATIONS   AND   AGREEMENTS  TO   SURVIVE   DELIVERY.      All
representations, warranties and agreements of the Company or of the Underwriters
herein  or in certificates delivered pursuant  hereto shall remain operative and
in full force and effect regardless of any investigation made by or on behalf of
any Underwriter or any controlling person, the Company, or any of its  officers,
directors,  or controlling persons, and shall  survive delivery of the Shares to
the several Underwriters hereunder.
 
    9.  SUBSTITUTION OF UNDERWRITERS.  If any Underwriter or Underwriters  shall
fail  to  take up  and pay  for the  number of  Shares to  be purchased  by such
Underwriter or Underwriters hereunder upon  tender of such Shares in  accordance
with   the   terms   hereof,   and   if   the   aggregate   number   of   Shares
 
                                       13
<PAGE>
which such  defaulting  Underwriter or  Underwriters  so agreed  but  failed  to
purchase  does not exceed 10% of the Shares, the remaining Underwriters shall be
obligated severally in proportion to  their respective commitments hereunder  to
take  up and pay for the Shares  of such defaulting Underwriter or Underwriters.
If one or more of the Underwriters shall fail or refuse (other than for a reason
sufficient to justify  the termination  of this  Agreement) to  purchase on  any
Closing  Date the  aggregate number  of Shares  agreed to  be purchased  by such
Underwriter or Underwriters  and the  aggregate number  of Shares  agreed to  be
purchased  by such Underwriter or Underwriters shall exceed 10% of the aggregate
number of Shares to be sold on any Closing Date hereunder by the Company to  the
Underwriters,  then the other  Underwriters shall have the  right to purchase or
procure one or more other underwriters to purchase, in such proportions as  they
may  agree  upon and  upon the  terms herein  set forth,  the Shares  which such
defaulting Underwriter or  Underwriters agreed to  purchase, and this  Agreement
shall  be carried  out accordingly. If  such other Underwriters  do not exercise
such right within thirty-six hours after  receiving notice of any such  default,
which  notice  the Representatives  shall have  also  promptly delivered  to the
Company, then  the Company  shall have  the right  to procure  another party  or
parties  reasonably satisfactory to the Representatives  to purchase or agree to
purchase such Shares on the terms herein set forth. If the Company is unable  to
procure  another such party, the Company may notify the Representatives that the
non-defaulting Underwriters are,  by the  giving of such  notice, released  from
their  obligations to purchase such number of Shares being sold hereunder by the
Company as  are indicated  in such  notice as,  when subtracted  from the  total
number  of Shares originally agreed  to be purchased by  all of the Underwriters
hereunder, shall  leave  a reduced  number  of Shares  to  be purchased  by  the
non-defaulting  Underwriters not  in excess of  110% of the  aggregate number of
Shares originally contracted  to be  purchased hereunder  by the  non-defaulting
Underwriters,  and each of them, in which event such non-defaulting Underwriters
shall purchase  such reduced  number of  Shares. In  any such  case, either  the
Representatives or the Company shall have the right to postpone any Closing Date
for  a  period of  not more  than seven  business days  in order  that necessary
changes and arrangements may be effected by the Representatives and the Company.
If  neither  the  non-defaulting  Underwriters   nor  the  Company  shall   make
arrangements  within the period stated for the purchase of the Shares which such
defaulting Underwriter  or  Underwriters  agreed  to  purchase,  including  such
arrangements  for the purchase of a reduced number of Shares as are provided for
in this Section 9, then this Agreement shall terminate without liability on  the
part  of any non-defaulting Underwriters to the Company and without liability on
the part of the Company to the Underwriters, provided that this Agreement  shall
not  terminate if such  events relate to the  sale of Option  Shares at a Second
Closing Date.
 
    In the event of any termination of this Agreement pursuant to the  preceding
paragraph  of this Section, the Company shall  not be under any liability to any
Underwriter (except as  provided in  Section 4(g) and  6 hereof)  nor shall  any
Underwriter (other than an Underwriter who shall have failed, otherwise than for
some  reason permitted under this Agreement, to purchase the number of Shares to
be purchased  by  such Underwriter  hereunder,  which Underwriter  shall  remain
liable to the Company and the other Underwriters for damages resulting from such
default)  be under any liability to the Company (except as provided in Section 6
hereof).
 
    The  term  "Underwriter"  in  this   Agreement  shall  include  any   person
substituted for an Underwriter under this Section 9.
 
    10.   EFFECTIVE DATE OF THIS AGREEMENT  AND TERMINATION.  (a) This Agreement
shall become effective at such time  after the declaration by the Commission  of
the  effectiveness of the Registration Statement as you in your discretion shall
first release  the Shares  for sale  to the  public. For  the purposes  of  this
Section  the Shares shall be deemed to have been released for sale to the public
upon release by you for publication of a newspaper advertisement relating to the
Shares or upon release by  you of letters or  telegrams offering the Shares  for
sale  to securities  dealers, whichever shall  first occur. By  giving notice as
hereinafter specified before the time this Agreement becomes effective, you,  as
Representatives of
 
                                       14
<PAGE>
the  several  Underwriters,  or  the Company  may  prevent  this  Agreement from
becoming effective  without  liability  on  the  part  of  the  Company  to  any
Underwriter  or of  any Underwriter  to the Company,  other than  as provided in
Sections 4(g) and 6 hereof.
 
         (b)
       You, as Representatives of the several Underwriters, shall have the right
       to terminate this Agreement by giving notice as hereinafter specified  at
any  time at or  prior to the First  Closing Date if (i)  the Company shall have
failed, refused  or been  unable, at  or prior  to the  First Closing  Date,  to
perform any material agreement on its part to be performed, or because any other
material  condition of  the Underwriters'  obligations hereunder  required to be
fulfilled by the Company is  not fulfilled; (ii) trading  on the New York  Stock
Exchange  shall have  been suspended, or  minimum or maximum  prices for trading
shall have been fixed,  or maximum ranges for  prices for securities shall  have
been  required, on the New York Stock Exchange by the New York Stock Exchange or
by  order  of  the  Commission  or  any  other  governmental  authority   having
jurisdiction,  since the execution of this Agreement; (iii) a banking moratorium
shall have been declared by Federal or New York authorities since the  execution
of  this Agreement; or (iv)  an outbreak of major  hostilities or other national
calamity shall have occurred. Any such termination shall be without liability on
the part of the Company to any Underwriter or of any Underwriter to the  Company
other than as provided in Sections 4(g) and 6 hereof.
 
         (c)
       If  you elect  to prevent  this Agreement  from becoming  effective or to
       terminate this Agreement as provided  in this Section, the Company  shall
be  notified promptly by you  by telephone or telegram,  confirmed by letter. If
the Company shall elect to prevent  this Agreement from becoming effective,  you
shall be notified promptly by the Company by telephone or telegram, confirmed by
letter.
 
    11.   NOTICES.   All notices  or communications hereunder,  except as herein
otherwise specifically provided, shall be in writing and if sent to you shall be
mailed, delivered  or  telecopied and  confirmed  to  you c/o  Allen  &  Company
Incorporated,  711 Fifth Avenue, New  York, New York 10022,  with copy to Werbel
McMillin & Carnelutti, a Professional  Corporation, 711 Fifth Avenue, New  York,
New  York 10022,  Attention: Robert H.  Werbel, Esq.  or if sent  to the Company
shall be mailed, delivered  or telecopied and confirmed  to the Company at  9610
Medical  Center Drive, Suite 200, Rockville, Maryland 20850, Attention: Dr. John
W. Holaday with a copy to Bachner, Tally, Polevoy & Misher LLP, Attention:  Jill
Cohen,  Esq. Notice to  any Underwriter pursuant  to Section 6  shall be mailed,
delivered or telecopied and confirmed to such Underwriter's address as set forth
in its  Master  Agreement  Among  Underwriters  furnished  to  Allen  &  Company
Incorporated.
 
    12.   PARTIES.  This Agreement shall inure  to the benefit of and be binding
upon the several Underwriters  and the Company  and their respective  successors
and  assigns. Nothing  expressed or mentioned  in this Agreement  is intended or
shall be construed  to give any  person or corporation,  other than the  parties
hereto  and their respective successors and assigns and the controlling persons,
officers and directors referred to in  Section 6, any legal or equitable  right,
remedy  or claim under or  in respect of this  Agreement or any provision herein
contained; this  Agreement  and  all  conditions  and  provisions  hereof  being
intended  to be  and being  for the  sole and  exclusive benefit  of the parties
hereto and their respective successors and assigns and said controlling  persons
and  said officers  and directors,  and for  the benefit  of no  other person or
corporation. No purchaser  of any of  the Shares from  any Underwriter shall  be
construed a successor or assign merely by reason of such purchase.
 
    In  all dealings with the Company under this Agreement, you shall be and are
authorized to act on behalf of each of the several Underwriters, and the Company
shall be  entitled  to  act and  rely  upon  any statement  request,  notice  or
agreement  on behalf of each of the  several Underwriters if the same shall have
been made or given in writing by you.
 
                                       15
<PAGE>
    13.  APPLICABLE LAW.  This Agreement shall be governed by and construed  and
enforced  in accordance  with the laws  of the  State of New  York applicable to
agreements made, and to be fully performed, therein.
 
    14.  COUNTERPARTS.  This Agreement  may be executed in several  counterparts
and  all documents so executed shall constitute one agreement, binding on all of
the parties hereto,  notwithstanding that all  of the parties  did not sign  the
original or the same counterparts.
 
    If  the foregoing correctly sets forth the understanding between the Company
and the several Underwriters, please so indicate in the space provided below for
that purpose whereupon this letter shall constitute a binding agreement  between
the Company and the several Underwriters.
 
                                          Very truly yours,
                                          ENTREMED, INC.
                                          By: __________________________________
                                                        President
 
Accepted as of the date
first above written:
ALLEN & COMPANY INCORPORATED
DILLON, READ & CO. INC.
VOLPE, WELTY & COMPANY
By: ALLEN & COMPANY INCORPORATED
By: ____________________________________________________________________________
On behalf of each of the several
Underwriters named in Schedule A hereto.
 
                                       16

<PAGE>
   
                                                                     EXHIBIT 5.1
    
 
   
                                                June 6, 1996
    
 
   
EntreMed, Inc.
9610 Medical Center Drive
Suite 200
Rockville, MD 20850
    
 
   
        RE:  REGISTRATION STATEMENT ON FORM S-1
    
 
   
Ladies and Gentlemen:
    
 
   
    We  have acted  as counsel for  EntreMed, Inc., a  Delaware corporation (the
"Company"), in connection with its registration statement on Form S-1 (File  No.
333-3536) (the "Registration Statement") filed under the Securities Act of 1933,
as  amended (the  "Act"), relating  to the  public offering  of up  to 3,680,000
shares of the Company's Common Stock, $.01 par value (the "Common Stock"), which
includes 480,000 shares  subject to  an option  granted to  the underwriters  to
cover over-allotments in connection with the offering.
    
 
   
    We  have examined the Amended and  Restated Certificate of Incorporation and
By-Laws of the Company, the minutes of the various meetings and consents of  the
Board of Directors of the Company, drafts of the Underwriting Agreement relating
to  the offering  of the  shares, draft  forms of  certificates representing the
Common  Stock,  originals  or  copies  of  all  such  records  of  the  Company,
agreements,  certificates  of  public officials,  certificates  of  officers and
representatives of the Company and others, and such other documents and  records
as we have deemed necessary to form the basis of the opinion expressed below. In
such  examination,  we  have  assumed the  genuineness  of  all  signatures, the
authenticity of all documents submitted to us as originals and the conformity to
originals of all  documents submitted  to us as  copies thereof.  As to  various
questions  of fact material to such opinion,  we have relied upon statements and
certificates of officers and representatives of the Company and others.
    
 
   
    Based upon  the  foregoing,  we are  of  the  opinion that  the  maximum  of
3,680,000  shares  have  been  duly  authorized and,  when  issued  and  sold in
accordance with the  terms described  in the Prospectus  forming a  part of  the
Registration  Statement (the "Prospectus"),  will be validly  issued, fully paid
and nonassessable.
    
 
   
    We hereby  consent  to  the use  of  this  opinion as  Exhibit  5.1  to  the
Registration  Statement, and  to the  use of our  name under  the caption "Legal
Matters" in the Prospectus.
    
 
   
                                            Very truly yours,
    
 
   
                                            BACHNER, TALLY, POLEVOY
                                              & MISHER LLP
    

<PAGE>
                                                                    EXHIBIT 11.1
 
                                 ENTREMED, INC.
                     COMPUTATION OF EARNINGS PER SHARE (1)
 
   
<TABLE>
<CAPTION>
                                                                                YEAR ENDED
                                                                               DECEMBER 31,
                                                                              --------------
                                                                                   1995
                                                                              --------------   THREE MONTH
                                                                                               PERIOD ENDED
                                                                                                MARCH 31,
                                                                                              --------------
                                                                                                   1996
                                                                                              --------------
                                                                                               (UNAUDITED)
<S>                                                                           <C>             <C>
Weighted average common and common equivalent shares outstanding during the
 period.....................................................................       5,485,763       6,438,017
Effect of common stock issued and stock options and warrants granted
 subsequent to April 12, 1995 computed in accordance with the treasury stock
 method as required by the SEC (2)..........................................       1,786,180         874,018
Conversion of preferred stock (3)...........................................       2,000,000       2,000,000
                                                                              --------------  --------------
Pro forma weighted average number of shares outstanding (3).................       9,271,943       9,312,035
                                                                              --------------  --------------
                                                                              --------------  --------------
Pro forma net loss per share (3)............................................  $        (0.83) $        (0.18)
                                                                              --------------  --------------
                                                                              --------------  --------------
</TABLE>
    
 
- ------------------------------
(1)  All  share information has been adjusted to reflect a two-for-three reverse
     stock split.
 
(2)  Pursuant to Securities  and Exchange Commission  Staff Accounting  Bulletin
     No.  83, Common and  Preferred Stock issued and  stock options and warrants
     grants at prices below the assumed initial public offering price of  $15.00
     per  share  during the  12-month period  immediately preceding  the initial
     filing date of the Company's Registration Statement for its initial  public
     offering  have been included as outstanding for all periods presented using
     the treasury stock method.
 
   
(3)  Pro forma net loss  per share and weighted  average shares outstanding  for
     the year ended December 31, 1995 and the three month period ended March 31,
     1996  give  effect to  the  automatic conversion  of  3,000,000 outstanding
     shares of Preferred Stock into 2,000,000 shares of Common Stock on the date
     of this Prospectus.
    

<PAGE>
                                                                    EXHIBIT 23.2
 
                        CONSENT OF INDEPENDENT AUDITORS
 
    We  consent  to the  references  to our  firm  under the  captions "Selected
Financial Data" and "Experts"  and to the  use of our  report dated January  25,
1996  (except  for Note  13, as  to which  the date  is March  29, 1996)  in the
Registration Statement on Form S-1 and  related Prospectus of EntreMed Inc.  for
the registration of 4,025,000 shares of its Common Stock.
 
                                          ERNST & YOUNG LLP
   
Atlanta, Georgia,
June 6, 1996
    


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