NEORX CORP
8-K, 1997-10-07
IN VITRO & IN VIVO DIAGNOSTIC SUBSTANCES
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                       SECURITIES AND EXCHANGE COMMISSION

                             Washington, D.C. 20549

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



                                    Form 8-K

                                 CURRENT REPORT



                     Pursuant to Section 13 or 15(d) of the
                         Securities Exchange Act of 1934



                                October 7, 1997
                  -------------------------------------------
                                (Date of Report)



                                NEORX CORPORATION
- --------------------------------------------------------------------------------
               (Exact Name of Registrant as Specified in Charter)

          Washington                   0-16614                  91-1261311
- -------------------------------- ------------------------  ---------------------
   (State or Other Jurisdiction   (Commission File No.)      (IRS Employer
        of Incorporation)                                    Identification No.)

               410 West Harrison Street, Seattle, Washington 98119
- --------------------------------------------------------------------------------
               (Address of principal executive offices) (Zip Code)

                                 (206) 281-7001
- --------------------------------------------------------------------------------
              (Registrant's telephone number, including area code)


<PAGE>


Item 5.  Other Events.

         NeoRx  Corporation (the "Company")  entered into an Agreement on August
8, 1997 (the "Agreement") with Janssen Pharmaceutica N.V. ("Janssen"),  a wholly
owned  subsidiary  of  Johnson  &  Johnson,   for  the  worldwide   development,
manufacture  and  distribution  of  the  Company's  Avicidin(R)  cancer  therapy
product.  As a result of the Agreement,  the Company received an initial payment
of $10 million,  of which fifty percent was for the purchase of equity  pursuant
to the preferred  stock  purchase  agreement  described  below.  The Company may
receive up to an  additional  $50  million in  payments  for  achieving  certain
milestones.  In  addition,  Janssen  has  agreed  to assume  responsibility  for
registration  and  commercialization  of the  product  and to fund an  estimated
ninety-five  percent of the remaining costs for product development and clinical
trials. In exchange,  Janssen receives a worldwide exclusive license to Avicidin
and the right of first negotiation to subsequent oncology products employing the
Company's  proprietary  Pre-Targeting  technology.  Additional oncology products
that fall under the Agreement will trigger royalty obligations and may result in
additional  milestone  payments to the Company.  The Company has retained  broad
development and marketing rights for its Pre-Targeting technology.

         In connection  with the  Agreement,  the Company also on August 8, 1997
entered  into a  Preferred  Stock  Purchase  Agreement  with  Johnson  & Johnson
Development  Corporation ("JJDC"),  pursuant to which the Company issued to JJDC
1,000 shares of its Series 4  Convertible  Preferred  Stock,  par value $.02 per
share (the "Series 4 Stock"), for an aggregate purchase price of $5,000,000. The
Series 4 Stock  converted  automatically  into 833,333  shares of the  Company's
common stock,  par value $.02 per share (the "Common  Stock"),  on September 12,
1997,  the date on which the  average  market  price of the Common  Stock for 15
consecutive  trading  days was equal to or greater  than  $6.00.  As  restricted
stock,  the shares of Common Stock are subject to certain  trading  restrictions
for two years.


                                       1

<PAGE>



Item 7.  Financial Statements, Pro Forma Financial Information and Exhibits.

10.1* Agreement, entered into as of July 1, 1997, between Janssen Pharmaceutica,
      N.V., and the Company.

10.2  Preferred Stock Purchase Agreement, dated as of August 8, 1997, between
      the Company and Johnson & Johnson Development Corporation.




     *Confidential  portions  of this  exhibit  have been  omitted and have been
files  separately  with the  Securities and Exchange  Commission  pursuant to an
application  for  confidential  treatment  under Rule 24b-2 under the Securities
Exchange Act of 1934 as amended.


                                       2

<PAGE>



                                    SIGNATURE

         Pursuant to the  requirements  of the Securities  Exchange Act of 1934,
the  registrant  has duly  caused  this report to be signed on its behalf by the
undersigned hereunto duly authorized.

                                        NEORX CORPORATION



Dated:  October 7, 1997                By    /s/ RICHARD L. ANDERSON
                                              -----------------------
                                              Richard L. Anderson
                                              Senior Vice President, Chief
                                              Financial Officer, Secretary and
                                              Treasurer




                                       3

<PAGE>

<TABLE>
<CAPTION>


                                  EXHIBIT INDEX

Exhibit Number           Description


             
<S>                      <C>             
10.1*                    Agreement, entered into as of July 1, 1997, between
                         Janssen Pharmaceutica, N.V., and the Company.

10.2                     Preferred Stock Purchase Agreement,  dated as of August
                         8, 1997,  between  the  Company  and  Johnson & Johnson
                         Development Corporation.


</TABLE>

- --------


         * Confidential portions of this exhibit have been omitted and have been
filed  separately  with the  Securities and Exchange  Commission  pursuant to an
application  for  confidential  treatment  under Rule 24b-2 under the Securities
Exchange Act of 1934, as amended.


                                       4









                                  EXHIBIT 10.1



                                       TO



                               NeoRx Corporation's



                               Report on Form 8-K



                                      Dated



                               October 7, 1997











         "[ * ]" =  omitted,  confidential  material,  which  material  has been
separately  filed with the  Securities  and  Exchange  Commission  pursuant to a
request for confidential treatment.



<PAGE>







                                    AGREEMENT

                                     between

                           Janssen Pharmaceutica, N.V.

                                       and

                                NeoRx Corporation





<PAGE>




                                    CONTENTS

<TABLE>
<CAPTION>

<S>                                                                                                      <C>
AGREEMENT ...........................................................................................    1
RECITALS ............................................................................................    1
I.       DEFINITIONS ................................................................................    1
II.      DEVELOPMENT ................................................................................   11
         2.1      Janssen's Responsibilities ........................................................   11
         2.2      NeoRx's Responsibilities ..........................................................   11
         2.3      Development Committee .............................................................   12
         2.4      Additional Products ...............................................................   13
         2.5      FDA ...............................................................................   13
         2.6      IND Transfer ......................................................................   13
         2.7      Research Audit ....................................................................   14
         2.8      Capital Expenditures ..............................................................   14
III.     LICENSE GRANTS .............................................................................   14
         3.1      License for Pre-Targeting Products ................................................   14
         3.2      Sublicense Rights .................................................................   15
         3.3      Distribution ......................................................................   15
         3.4      Nonexclusive Know-How License to NeoRx ............................................   15
         3.5      Nonexclusive Know-How License to Janssen ..........................................   15
         3.6      Third-Party Agreements ............................................................   15
         3.7      No Other Rights ...................................................................   16
         3.8      Prohibition .......................................................................   16
IV.      PAYMENTS ...................................................................................   16
         4.1      Upfront Payments ..................................................................   16
         4.2      Milestone Payments for the First Pre-Targeting Product ............................   16
         4.3      Milestones for a Second Type of Pre-Targeting Product .............................   17
         4.4      Earned Royalties for Primary Pre-Targeting Products ...............................   18
         4.5      Royalty Adjustment in U.S. for Primary Pre-Targeting Products .....................   18
         4.6      Earned Royalties for Additional Products ..........................................   20
         4.7      Royalty Adjustment in U.S. for Additional Products ................................   20
         4.8      Duration of Royalty Payments ......................................................   20
         4.9      Reduction in Royalty Rate in Response to Generic Competition ......................   21
         4.10     Reduction in Royalty Rate in Response to Substitute Product Competition ...........   21
         4.11     Reduction in Royalty Rate for Jointly Owned Patents ...............................   22
         4.12     Foreign Exchange ..................................................................   22
         4.13     [Intentionally Left Blank] ........................................................   22
<PAGE>

         4.14     Taxes .............................................................................   22
         4.15     Records, Reports and Payment ......................................................   23
         4.16     Accounting ........................................................................   23
         4.17     Third Party Patents ...............................................................   24
         4.18     Compulsory License ................................................................   25
         4.19     No Multiple Royalties; Third Party Royalties ......................................   25
         4.20     Value of Collaboration in NeoRx Know-How ..........................................   26
         4.21     No Multiple Reductions ............................................................   26
         4.22     Allocation of Annual Net Sales [   *   ] ..........................................   26
V.       JANSSEN'S OPTION TO EXPAND FIELD AND INDEPENDENT DEVELOPMENT ...............................   27
         5.1      Janssen's Option to Expand the Field ..............................................   27
         5.2      Exercise of Janssen's Option ......................................................   27
         5.3      Limitation on NeoRx Right to Assign or License Prior to Exercise by
                  Janssen of Its Option .............................................................   27
         5.4      NeoRx Right to Independently Develop Pre-Targeting Products Within the
                  Field .............................................................................   28
         5.5      NeoRx Obligation to Re-Offer ......................................................   28
         5.6      Limitations on NeoRx Rights During Re-Offer Period ................................   29
         5.7      Janssen's Right of First Negotiation to Expand the Field Further ..................   30
VI.      CO-PROMOTION ...............................................................................   30
         6.1      Co-Promotion Option of NeoRx ......................................................   30
         6.2      Co-Promotion Limitation of Scope ..................................................   31
         6.3      NeoRx Is Not a Distributor ........................................................   33
         6.4      Joint Marketing and Sales Committee ...............................................   33
         6.5      Co-Promotion Obligations ..........................................................   33
         6.6      Costs Associated With Co-Promotion ................................................   34
         6.7      Co-Promotion Compliance ...........................................................   34
         6.8      Co-Promotion Audit of Performance .................................................   34
         6.9      Co-Promotion Termination for Cause ................................................   35
         6.10     Co-Promotion Is Through Independent Organizations .................................   36
         6.11     Co-Promotion Does Not Affect Certain Responsibilities .............................   36
         6.12     NeoRx Right to Terminate ..........................................................   37
         6.13     Trademarks ........................................................................   37
         6.14      Indemnification for Products .....................................................   38

[  *  ] Confidential Treatment Requested


                                      -ii-

<PAGE>


         6.15     Marketing Liaison .................................................................   38
         6.16     Dispute Resolution ................................................................   39
         6.17     Transferability of Co-Promotion Right .............................................   39
VII.     MANUFACTURE ................................................................................   40
         7.1      Janssen's Responsibility ..........................................................   40
         7.2      Janssen's Obligation ..............................................................   40
VIII.    PATENTS ....................................................................................   40
         8.1      Maintenance of NeoRx Patents ......................................................   40
         8.2      Failure by NeoRx to Prosecute and/or Maintain .....................................   41
         8.3      Ownership of Patents ..............................................................   41
         8.4      Disclosure of Patentable Inventions ...............................................   41
         8.5      Jointly Owned Patent Filings ......................................................   42
         8.6      Parties' Cooperation in Obtaining Patent Extensions ...............................   42
IX.      INFRINGEMENT ...............................................................................   42
         9.1      Infringement of Third Party Patents ...............................................   42
         9.2      Infringement by Third Parties of NeoRx Patents ....................................   43
         9.3      Infringement by Third Parties of Jointly Owned Patents ............................   43
X.       TRADEMARKS AND CORPORATE NAME ..............................................................   44
XI.      CONFIDENTIALITY ............................................................................   44
         11.1     Confidentiality; Exceptions .......................................................   44
         11.2     Authorized Disclosure .............................................................   45
         11.3      Survival .........................................................................   45
XII.     REPRESENTATIONS AND WARRANTIES; PERFORMANCE.................................................   45
         12.1     Representations and Warranties ....................................................   45
         12.2     Disclaimer ........................................................................   46
         12.3     Performance by Affiliates .........................................................   46
XIII.    TERM AND TERMINATION .......................................................................   46
         13.1     Term ..............................................................................   46
         13.2     Termination for Breach ............................................................   46
         13.3     Termination for Bankruptcy ........................................................   47
         13.4     Janssen's Termination Without Cause ...............................................   47
         13.5     Rights and Obligations Upon Termination Under Paragraph 13.2 or 13.3 by
                  NeoRx or Under Paragraph 13.4 by Janssen ..........................................   47
         13.6     Survival ..........................................................................   48
         13.7     Accrued Rights, Surviving Obligations .............................................   48
         13.8     Termination Not Sole Remedy .......................................................   48
XIV.     INDEMNIFICATION ............................................................................   48
         14.1     Research and Development Indemnification ..........................................   48

                                     -iii-

<PAGE>

         14.2     Janssen Indemnification ...........................................................   49
         14.3     Notification ......................................................................   49
V.      DISPUTE RESOLUTION ..........................................................................   49
         15.1     Alternative Dispute Resolution ....................................................   49
         15.2     Arbitration Procedure .............................................................   49
                  (a)      Arbitrator ...............................................................   50
                  (b)      Proceedings ..............................................................   50
                  (c)      Award ....................................................................   52
                  (d)      Costs ....................................................................   52
                  (e)      Confidentiality ..........................................................   52
         15.3     Survivability .....................................................................   52
         15.4     Jurisdiction ......................................................................   52
XVI.     LICENSOR BANKRUPTCY ........................................................................   53
XVII.    NOTICES ....................................................................................   53
XVIII.   PUBLICITY ..................................................................................   54
         18.1     Publicity .........................................................................   54
         18.2     Scientific Publications ...........................................................   55
XIX.     FORCE MAJEURE ..............................................................................   55
XX.      INTEGRATION ................................................................................   56
XXI.     MISCELLANEOUS ..............................................................................   56
         21.1      Amendments .......................................................................   56
         21.2     Laws ..............................................................................   56
         21.3     Severability ......................................................................   56
         21.4     Headings ..........................................................................   57
         21.5     Waiver ............................................................................   57
         21.6     Representations ...................................................................   57
         21.7     Compliance With Laws ..............................................................   57
         21.8     Relationship of Parties ...........................................................   57
         21.9     Interest ..........................................................................   58
         21.10    Counterparts ......................................................................   58
EXHIBIT A  COST OF GOODS SOLD .......................................................................    1
EXHIBIT B  NEORX PATENTS ............................................................................    1
EXHIBIT C  NEORX COST CATEGORIES ....................................................................    1
EXHIBIT D  12/4/96 Letter from P. Verheyen ..........................................................    1


                                      -iv-

</TABLE>
<PAGE>




                                    AGREEMENT


         This Agreement is entered into as of this 1st day of July,  1997 by and
between Janssen  Pharmaceutica,  N.V., having its principal place of business at
Turnhoutseweg  30, 2340  Beerse,  Belgium  ("Janssen"),  and NeoRx  Corporation,
having its  principal  place of business at 410 West Harrison  Street,  Seattle,
Washington  98119-4004  ("NeoRx").  Janssen and NeoRx are sometimes  referred to
herein individually as a "Party" and collectively as the "Parties."

                                    RECITALS

         WHEREAS,  NeoRx has begun  Development  (hereinafter  defined) of NeoRx
Pre-Targeting  Technology  (hereinafter  defined)  for the  delivery  of a [ * ]
Effector  Molecule  (hereinafter  defined)  localized  at a tumor,  which may be
particularly useful in cancer therapy.

         WHEREAS, this NeoRx Pre-Targeting  Technology has resulted in a product
called Avicidin(R)  (hereinafter  defined) now in Development by NeoRx for small
cell lung cancer.

         WHEREAS,   Janssen  is  a  pharmaceutical   company  with  a  worldwide
development and marketing organization.

         WHEREAS,   Janssen   desires   to  develop   Pre-Targeting   Product(s)
(hereinafter defined) employing NeoRx Pre-Targeting  Technology,  including, but
not limited to,  Avicidin,  with NeoRx and to receive license rights to develop,
manufacture and market the Pre-Targeting Product(s) that result therefrom.

         NOW, THEREFORE, the Parties agree as follows:

                                 I. DEFINITIONS

         The following  terms shall have the following  meanings as used in this
Agreement:

         1.1......"Actual Cost of Goods Percentage" or "Al" shall have the mean-
ing recited in Paragraph 4.5(a).

         1.2 ....."Additional Product" means a Pre-Targeting Product that is not
a Primary  Pre-Targeting  Product,  [ * ].  Additional  Products  are  developed
pursuant to Paragraph 2.4.

[  *  ] Confidential Treatment Requested

                                      -1-
<PAGE>


         1.3......"Affiliate"  means an entity  that,  directly  or  indirectly,
through  one or more  intermediaries,  controls,  is  controlled  by or is under
common  control with  Janssen or NeoRx.  As used in this  definition,  "control"
shall be  presumed if there is  ownership,  directly  or  indirectly,  of thirty
percent (30%) or more (or, if less, the maximum  permitted by applicable law) of
the voting stock, equity or income interest of an entity.

         1.4......"Anti-Ligand"  means a composition of matter that demonstrates
high  affinity,  and,  preferably,  multivalent  binding,  of the  complementary
Ligand. Avidin is an example of an Anti-Ligand.

         1.5......"Avicidin"  means a product designed for  administration  to a
patient as three separate  components  comprising a first  component  comprising
NR-LU-10 bound to Avidin, a second  component  comprising a Clearing Agent and a
third component comprising yttrium-90 bound to biotin or its functional analog.

         1.6......"Avidin"  means  avidin,   streptavidin  and  derivatives  and
analogs  thereof  that are capable of high  affinity,  multivalent  or univalent
binding to biotin or its functional analogs.

         1.7......"Bind(s)"  means, solely with respect to Paragraph 1.25(b) and
the binding to a cell line,  that an  antibody  demonstrates  a greater  than or
equal to [ * ] increase in medium channel fluorescence intensity over a negative
control in a flow cytometry  system using directly  labeled antibody when tested
on that cell line in the presence of human IgG. [ * ].

         1.8......"BLA"  means a Product License Application filed with the FDA,
as more  fully  defined  in 21  C.F.R.  Part  600 et  seq.,  or any  replacement
application for Regulatory Approval in the United States.

         1.9......"Clearing  Agent"  means a  composition  of matter  capable of
binding,  complexing or otherwise associating with an administered moiety (e.g.,
Targeting  Agent-Ligand,   Targeting  Agent-Anti-Ligand  or  Anti-Ligand  alone)
present in the recipient's circulation,  thereby facilitating circulating moiety
clearance  from  the  recipient's  body,   removal  from  blood  circulation  or
inactivation thereof in circulation.

         1.10....."Control"  means  possession of the ability to grant a license
or sublicense as provided for herein without violating the terms of an agreement
or other arrangement.

[  *  ] Confidential Treatment Requested

                                      -2-
<PAGE>


         1.11....."Co-Promote"   or  "Co-Promotion"  means  to  promote  jointly
Avicidin  or another  Pre-Targeting  Product  hereunder  through  Janssen's  and
NeoRx's respective sales forces under a single trademark in the United States.

         1.12....."Cost  of Goods Sold" means the cost of Pre-Targeting  Product
(excluding  the  Ligand/Effector  Molecule  conjugate)  inventory sold and other
manufacturing-related  costs with respect to the  Pre-Targeting  Product.  These
costs  shall  be  defined  as the sum of the  applicable  expenditures  incurred
directly  in bringing  goods  acquired  and/or  manufactured  to their  existing
condition or location.  Cost of Goods Sold shall be calculated in the manner set
forth in Exhibit A attached hereto.

         1.13....."Crossover Field" means the field described in Paragraph
 1.25(c).

         1.14....."Date  of First  Sale"  means  the day on which  Janssen,  its
Affiliate  or its  sublicensee  first sells a  Pre-Targeting  Product to a Third
Party (excluding  sublicensees) in a commercial  arm's-length  transaction after
Regulatory Approval.

         1.15....."Details"  shall  mean  face-to-face   presentations  made  to
physicians,  nurses,  P&T committee  members and other  individuals  who provide
direct  health care  services to patients,  in their  capacity as such.  Details
shall not include calls on managed care  organizations in an attempt to secure a
contract  with  such  organization.  Details  shall  also not  include  calls on
administrators or other such individuals in charge of deciding what is placed on
a  formulary  in  hospitals  or  teaching   institutions.   Once,  however,  the
Pre-Targeting   Product  is  on  a  formulary  of  such   hospital  or  teaching
institution,  Details shall include  calls to health care  professionals  in the
hospital or teaching institution. Details may also include, if agreed in advance
by Janssen  and NeoRx,  calls on P&T  committee  members of such  hospitals  and
teaching  institutions  in an  attempt  to get the  Pre-Targeting  Product  on a
formulary.

         1.16....."Development"  means  all  activities  relating  to  obtaining
Regulatory  Approval of a  Pre-Targeting  Product,  line  extensions,  alternate
delivery  systems and new  indications  therefor and all activities  relating to
developing  the  ability to  manufacture  the same.  This  includes,  but is not
limited  to,  preclinical  testing,  toxicology,  formulation,  bulk  production
fill/finish,   manufacturing  process  development,  manufacturing  and  quality
assurance  technical  support,  clinical  studies  and  regulatory  affairs.  In
addition,  Development  also includes  those  research  activities  necessary to
develop certain new or different components of the Pre-Targeting Product such as
the Clearing Agent or fusion protein.

         1.17 ...."Development Committee" means that committee described in
Paragraph 2.3.

                                      -3-
<PAGE>


         1.18  ...."Development  Costs"  means the  costs,  including  allocable
overhead,  incurred by a Party or for its account,  specifically identifiable to
the  Development of a  Pre-Targeting  Product or an Independent  Product that is
aimed at  achieving  Regulatory  Approval of such  Product,  including,  but not
limited to, [ *  ].

         1.19....."Development Plan" means the plan for Development of a Primary
Pre-Targeting Product agreed to by the Parties and attached to a separate letter
exchanged between the Parties concurrently  herewith,  as amended and revised in
accordance with this Agreement, and plans for Development of other Pre-Targeting
Products.

         1.20....."Drug   Approval   Application"   means  an  application   for
Regulatory  Approval  required before  commercial sale or use of a Pre-Targeting
Product as a drug in a regulatory jurisdiction.

         1.21....."Effective Date" means the date first written above.

         1.22....."Effector Molecule" means a therapeutic agent, including, but
 not limited to, [   *   ].

         1.23....."Expansion   Field"  means  the  therapeutic  applications  in
oncology  of NeoRx  Pre-Targeting  Technology  outside  of the  Field  where the
specific  antibody and the Effector  Molecule are owned or Controlled by (or are
covered by an option to acquire or license,  with right to sublicense,  held by)
NeoRx or its  Subsidiaries.  Janssen  has a right of  first  negotiation  to the
Expansion Field pursuant to Paragraph 5.7.

         1.24....."FDA" means the United States Food and Drug Administration or
 any successor agency.

         1.25....."Field" means:

[  *  ] Confidential Treatment Requested

                                      -4-

                                      
<PAGE>


         (a)......All    therapeutic   applications   in   oncology   of   NeoRx
Pre-Targeting  Technology  that use NR-LU-10 or any  antibody  that binds to the
NR-LU-10 antigen and any Effector Molecule.

         (b)......All therapeutic applications in oncology of NeoRx Pre-Target-
ing Technology that use [  *  ].

         (c)......Notwithstanding  the limitation to oncology  therapy in either
(a) or (b) above, (i) if a Pre-Targeting  Product  comprising  NR-LU-10,  or any
antibody  that binds to the  NR-LU-10  antigen,  and any  Effector  Molecule has
reached the stage in Development wherein [ * ].

         The Field may be expanded in accordance  with, and subject to the terms
of, Paragraphs 5.1 and 5.7.

         1.26....."FTE"   means  a  full-time  scientific  person  dedicated  to
Development  or,  in the  case of less  than a  full-time  dedicated  scientific
person,  a full-time,  equivalent  scientific  person year based upon a total of
forty-six  (46) weeks or one thousand eight hundred forty (1,840) hours per year
of scientific  work, on or directly  related to  Development,  carried out by an
employee. No FTE shall be a postdoctoral trainee of NeoRx. Scientific work on or
directly related to Development to be performed by employees can include, but is
not limited to, experimental  laboratory or clinical work, recording and writing
up results, reviewing literature and references, holding scientific discussions,
attending  appropriate  seminars and symposia,  managing and leading  scientific
staff, and carrying out management  duties related to Development.  Excluded are
administrative   facilities   support,    laboratory   administrative   support,
information  and  computer  support,  and other  internal  or  external  support
personnel involved in Development.

         1.27....."Generic Product" means a product sold in a particular country
(a) after the expiration in such country of [ * ] or its  corresponding  foreign
equivalent  that  (i) was not  made or sold by  Janssen,  its  Affiliate  or its
sublicensee   and  (ii)  has  the  same  components  and   configuration   as  a
Pre-Targeting  Product sold in the country or (b) that (i) is competitive with a
Pre-Targeting Product sold in the country, (ii) employs the technology described
in [ * ] or its corresponding foreign equivalent in such country,  (iii) is sold
under  the  license  rights  granted  under  the [ * ],  and (iv) is sold in any
quantity in the country.

[  *  ] Confidential Treatment Requested

                                      -5-
                                    
<PAGE>


         1.28....."IND" means an investigational new drug application filed with
the FDA as more fully defined in 21 C.F.R. ss. 312.3.

         1.29....."Independent   Product"   means  any   product  in  the  Field
(excluding the Crossover Field) for pharmaceutical use in humans employing NeoRx
Pre-Targeting   Technology  that  is  developed  by  NeoRx  in  accordance  with
Paragraphs  5.4, 5.5 and 5.6. An Independent  Product may become a Pre-Targeting
Product at the election of Janssen in accordance with Paragraph 5.4 or 5.5.

         1.30....."Information" means (a) information generally not known to the
public relating to the Field (excluding the Crossover Field), including, but not
limited to,  techniques  and data,  including,  but not limited to,  inventions,
practices, methods, knowledge,  know-how, skill, experience, test data including
pharmacological,  toxicological  and clinical test data,  analytical and quality
control data, marketing, pricing, distribution, costs, sales, manufacturing, and
patent and legal data or descriptions, and (b) reasonable research quantities of
compounds,  assays,  Clearing  Agents,  Ligand/Anti-Ligand  Pairs and biological
materials generally not known to the public relating to the Field (excluding the
Crossover  Field);  provided,  however,  that  "Information"  does  not  include
information,  compounds,  assays, Clearing Agents,  Ligand/Anti-Ligand  Pairs or
biological materials relating to Targeting Agents (other than NR-LU-10) or [ * ]
Effector Molecules and not relating to NR-LU-10 or [ * ] Effector Molecules.

         1.31....."Janssen   Know-How"  means   Information   that  (a)  Janssen
discloses to NeoRx under this  Agreement and (b) is now or hereafter  within the
Control of  Janssen;  provided,  however,  "Janssen  Know-How"  does not include
rights under any patents or patent applications.

         1.32....."Joint  Marketing  and  Sales  Committee"  means  a  committee
consisting of members from the marketing  and/or sales  functions of Janssen and
NeoRx.

         1.33....."Ligand"  means a small,  soluble molecule that exhibits rapid
serum,  blood and/or whole body clearance when administered  intravenously in an
animal. Biotin is an example of a Ligand.

         1.34....."Ligand/Anti-Ligand Pair"means a complementary/anti-complemen-
tary  set of molecules  that  demonstrates  specific binding,  generally  of 
relatively  high  affinity.  Biotin/streptavidin  is an example of a Ligand/Anti
- -Ligand Pair.

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         1.35....."Major European Market Country" means France, Germany, Great
Britain or Italy.

         1.36....."Marketing  Approval"  means  all  allowances  and  approvals,
including, but not limited to, Regulatory Approval and pricing and reimbursement
approvals  granted  by the  appropriate  federal,  state  and  local  regulatory
agencies,  departments,  bureaus or other governmental entities within a country
necessary to market and sell a product.

         1.37....."NeoRx Know-How" means Information that (a) NeoRx discloses to
Janssen under this  Agreement and (b) is now or hereafter  (subject to Janssen's
election under Paragraph 4.19) within the Control of NeoRx;  provided,  however,
"NeoRx   Know-How"   does  not  include  rights  under  any  patents  or  patent
applications.

         1.38....."NeoRx  Patents" means all the patents and patent applications
now or hereafter  (subject to Janssen's  election under Paragraph 4.19) owned or
Controlled  by  NeoRx  including  its  interest  in any  jointly  owned  patents
hereunder  relating to NeoRx  Pre-Targeting  Technology at any time, prior to or
during the term of this  Agreement,  a partial listing of which is identified in
Exhibit B,  attached  hereto,  and which  shall be updated by NeoRx from time to
time,  any  foreign   counterparts   thereof,  as  well  as  all  continuations,
continuations-in-part, divisions, provisional applications and renewals thereof,
all patents  that may be granted  thereon,  and all  reissues,  re-examinations,
extensions,  patents of addition and patents of importation  thereof;  provided,
however,  that "NeoRx Patents" does not include  patents or patent  applications
relating to Targeting Agents (other than NR-LU-10) or [ * ] Effector Molecules.

         1.39....."NeoRx  Pre-Targeting  Technology" means the technology now or
hereafter  (subject  to  Janssen's  election  under  Paragraph  4.19)  owned  or
Controlled by NeoRx that involves:  (a) target site  localization in the patient
by  administering  a  Targeting  Agent that is  conjugated  with one member of a
Ligand/Anti-Ligand   Pair  (a  first  component)  and  allowing  a  time  period
sufficient for optimal target  accumulation of this Targeting  Agent  conjugate;
and preferably after removing the nontarget bound Targeting Agent conjugate from
the patient with a Clearing Agent (a second component); and (b) administering to
the  patient an  Effector  Molecule  conjugated  to the  opposite  member of the
Ligand/Anti-Ligand  Pair (a third component) that binds (directly or indirectly)
to the Targeting Agent conjugate at the target site.

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         1.40....."Net  Sales"  means the gross sales price billed by a Party or
an  Affiliate  thereof  or a  sublicensee  thereof  for  sales of  Pre-Targeting
Products (including all components thereof) to a Third Party, less (in each case
as may be  applicable  thereto and  consistent  with such Party's then  existing
standard  business  practices):  (a) standard  trade  discounts,  including cash
discounts or rebates  actually  allowed or granted from the billed  amount;  (b)
credits or  allowances  actually  granted upon claims,  rejections or returns of
Pre-Targeting  Products,  including recalls,  regardless of the Party requesting
such recall;  (c) charges included as part of the gross sales price for freight,
postage,  shipping and insurance  charges,  to the extent billed, and separately
stated on the invoice; (d) taxes, duties or other governmental charges levied on
or measured by the billing  amount  when  included in billing,  as adjusted  for
rebates and refunds, and separately stated on the invoice; and (e) accounts that
are uncollectible and written off such Party's books as uncollectible; provided,
however,  that any  uncollectible  accounts excluded pursuant to this clause (e)
that are subsequently collected by such Party shall be included in Net Sales for
the royalty  period in which such  amounts are  collected.  Each  reference to a
Party set forth  above in this  Paragraph  1.40 shall be deemed to  include  and
apply  to  such  Party's  Affiliates  and  sublicensees,   as  applicable.   Any
Pre-Targeting   Product  sold  or  otherwise   disposed  of  in  other  than  an
arm's-length  transaction or for other property  (e.g.,  barter) shall be deemed
billed at its fair market  value in the country of sale or  disposition.  In the
event a Party is receiving  royalties under this Agreement from any Product sold
in the form of a  combination  Product  containing  or together with one or more
active ingredients or devices in addition to a Pre-Targeting  Product (including
all its components),  Net Sales for such combination  Product will be calculated
by multiplying Net Sales of such  combination  Product by the fraction  A/(A+B),
where A is the invoice price of the applicable  Pre-Targeting  Product,  if sold
separately,  and B is the  total  invoice  price of the  active  ingredients  or
active,  nonconsumable  devices  (such as,  for  example,  implantable  pumps or
electronic stimulators; however, items such as disposable transdermal patches or
prefilled syringes shall constitute  consumable devices) in the combination,  if
sold separately.  If, on a country-by  country basis, the other active component
or components in the combination  are not sold  separately in said country,  Net
Sales for the purpose of determining  royalties of the combination Product shall
be  calculated  by  multiplying  Net Sales of such  combination  Product  by the
fraction  A/C,  where A is the  invoice  price of the  applicable  Pre-Targeting
Product,  if sold  separately,  and C is the  invoice  price of the  combination
Product. If, on a country-by-country  basis, neither the combination Product nor
the other active  component or  components of the  combination  Product are sold
separately in said country, Net Sales for the purposes of determining  royalties
of the combination Product shall be determined by the Parties in good faith.


                                       8
<PAGE>


         1.41....."NR-LU-10"  means the antibody  whose binding  sequences  have
been  provided  in  writing to Janssen by NeoRx in a letter of even date and any
functional analog of such antibody that binds to the same tumor-specific antigen
(including,  but not  limited  to,  F(ab)'2,  Fab,  single  chain  fv and  human
antibodies).

         1.42....."Phase  II" means  that  portion of the  clinical  development
program that provides for the initial trials of a product on a limited number of
patients for the purposes of determining dose and evaluating safety and efficacy
in the proposed therapeutic indication as more fully defined in 21 C.F.R.
ss. 312.21(c) or foreign equivalent.

         1.43....."Pivotal  Phase  II/III"  means that  portion of the  clinical
development  program  that  provides  for a clinical  trial(s) of a product on a
sufficient  number of patients to establish the safety and efficacy of a product
and generate  pharmacoeconomic  data necessary to support Regulatory Approval in
the proposed therapeutic  indication(s) in the United States or a Major European
Market Country,  it being recognized and agreed that, with respect to the United
States, [ * ].

         1.44....."Pre-Targeting  Product"  means any  product  in the Field for
pharmaceutical  use in humans employing NeoRx  Pre-Targeting  Technology that is
developed  with NeoRx as  provided  herein.  Pre-Targeting  Products  are either
Primary Pre-Targeting  Products or Additional Products,  but are not Independent
Products.

         1.45....."Primary  Pre-Targeting Product" means a Pre-Targeting Product
that  comprises  a [ * ]  Effector  Molecule  used  with  NR-LU-10  or any other
Targeting Agent that binds to the NR-LU-10 antigen.

         1.46....."[   *   ] Effector Molecule" means an Effector Molecule that
is a [   *   ].

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         1.47....."Regulatory  Approval" means any approvals (including, but not
limited to, pricing and reimbursement  approvals,  product and/or  establishment
licenses,  registrations  or  authorizations  of any  federal,  state  or  local
regulatory agency,  department,  bureau or other governmental  entity) necessary
for the  manufacture,  use,  storage,  import,  export,  transport  or sale of a
Pre-Targeting Product in a regulatory jurisdiction.

         1.48....."Standard  Cost of Goods  Reference  Percentage" or "S1" shall
have the meaning recited in Paragraph 4.5.

         1.49....."Subsidiary"  means an entity that, directly or indirectly, is
controlled by Janssen or NeoRx. As used in this  definition,  "control" shall be
presumed under the same conditions as Paragraph 1.3.

         1.50....."Substitute  Product"  means a  product  sold in a  particular
country after the expiration in such country of the equivalent of [ * ] that (a)
was not made or sold by Janssen,  its Affiliate or its  sublicensee,  (b) can be
substituted  for, and is competitive  with, a Pre-Targeting  Product sold in the
country,  (c) has the same [ * ], and (e) does not  infringe a Valid  Claim of a
NeoRx Patent in the country because of the change described in clause (d).

         1.51....."Targeting  Agent" means a composition  of matter,  including,
but not limited to, an antibody,  that binds to a cell or defined  population of
cells.  A  Targeting  Agent  may  bind to a  receptor,  an  oligonucleotide,  an
enzymatic substrate,  an antigenic  determinant or other binding site present or
in the target cell population.

         1.52....."Third  Party"  means any entity  other than Janssen or NeoRx,
and their respective Affiliates.

         1.53....."Third   Party   Patents"   means  those  patents  and  patent
applications  (including foreign counterparts)  identified by NeoRx prior to the
Effective Date in writing to Janssen.

         1.54....."Third  Party  Royalties"  means  those  royalties  and  other
amounts that are or may be payable to those Third Parties previously  identified
by NeoRx in writing  to  Janssen  as a result of the use of NeoRx  Pre-Targeting
Technology or the manufacture, use or sale of a Pre-Targeting Product hereunder.

         1.55....."Third Party Royalty Rates" are those royalty rates associated
with the Third Party Royalties.

         1.56....."U.S.  Marketing  Plan"  means  a  marketing  plan  or  plans,
including, but not limited to, premarketing plans for specified periods of time,
that shall set forth promotion,  detailing and marketing  strategies  related to
each Pre-Targeting  Product to be sold in the United States,  including proposed
pricing and detailing.

         1.57....."Valid  Claim" means a claim of a pending  patent  application
being pursued in good faith or an issued, unexpired patent that has not been (a)

[  *  ] Confidential Treatment Requested

                                       10
<PAGE>


held invalid or  unenforceable  by a final  decision of a court or  governmental
agency of competent  jurisdiction,  which  decision is  unappealable  or was not
appealed  within the time  allowed  therefor,  or (b)  admitted in writing to be
invalid or unenforceable by the holder(s) by reissue, disclaimer or otherwise.

                                 II. DEVELOPMENT

2.1      Janssen's Responsibilities

         As  of  the  Effective  Date,  Janssen  shall  use  reasonable  efforts
consistent with its normal business  practices to develop and  commercialize  at
least one Pre-Targeting  Product (Avicidin is the initial  Pre-Targeting Product
to be developed by Janssen) and, with support from NeoRx described in Paragraphs
2.2 and 2.4, shall be solely  responsible for the  Development of  Pre-Targeting
Product(s),  including,  but not limited to,  preparing and filing Drug Approval
Applications in its own name and seeking Regulatory  Approvals for Pre-Targeting
Product(s).   All  costs  associated  with  its  Development  and  manufacturing
activities  shall be borne solely by Janssen,  except to the extent described in
Paragraph 2.2.  Janssen shall keep NeoRx informed of its Information  related to
Development of Pre-Targeting Products.

2.2      NeoRx's Responsibilities

         Promptly  following the Effective Date, NeoRx shall disclose to Janssen
Information within NeoRx's Control relating to NeoRx  Pre-Targeting  Technology,
including,  but not limited to, Avicidin,  and from time to time, as Information
becomes  available,  is generated  or is learned,  update such  disclosure  with
additional  Information  that it obtains  throughout the term of this Agreement.
Upon request,  NeoRx will provide  reasonable  quantities of physical  materials
(e.g.  compounds) for  evaluation.  In order to assure a smooth  transfer of the
responsibilities   for  Development  from  NeoRx  to  Janssen  for  the  Primary
Pre-Targeting  Product,  NeoRx will commit up to [ * ] FTEs/year  as assigned by
the Development Committee until December 31, 1998. Such FTEs shall carry out the
activities that are reasonably  assigned to them as described in the Development
Plan and that are within their  capabilities  (i.e.,  NeoRx is not  obligated to
hire additional scientists,  but is obligated to provide, as needed, up to [ * ]
FTEs  having the general  background  and skills of NeoRx's  current  scientific
staff and  having a mix of Ph.D.  to  non-Ph.D.  degrees  comparable  to NeoRx's
current staff working on Avicidin). It is expected that such FTEs shall, subject

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<PAGE>

to Development  Committee  approval,  [ * ], the maximum level of FTE support at
NeoRx shall be reduced to [ * ] FTEs for the Primary Pre-Targeting  Product. All
internal,  nonproject-related  costs associated with employing FTEs,  including,
but not  limited  to, [ * ],  shall be to the  account  of NeoRx  with the costs
associated with any capital  investments being treated as set forth in Paragraph
2.8. All costs  associated  with the  Development  conducted or  coordinated  by
NeoRx,  such as  having  material  produced  by a  Third  Party,  which  work is
preapproved  by  Janssen,  and any  other  costs  specifically  budgeted  in the
Development  Plan as  Janssen  expenses,  shall be to the  account  of  Janssen.
Janssen has approved  and will  reimburse  NeoRx within  twenty (20) days of the
date hereof for [ * ] of costs previously incurred by NeoRx. In carrying out the
activities  assigned  to it pursuant to the  Development  Plan,  NeoRx shall use
reasonable  efforts consistent with its normal business practices and the budget
set forth in the Development Plan. NeoRx shall have no obligation to incur costs
or perform work not in the Development Plan budget.  Any additional cost or cost
overruns of NeoRx not  provided  for in the  quarterly  Development  Plan budget
shall be to the account of NeoRx,  unless approved in writing in advance.  NeoRx
shall  invoice  Janssen  each  calendar  quarter  for the  Development  expenses
incurred  by it that are within the budget  recited in the  Development  Plan or
that have been otherwise approved in advance, together with a detailed statement
describing  the costs and  expenses  billed.  Janssen  shall make payment of the
amount  invoiced  within  thirty  (30) days of  receipt  of the  invoice.  It is
recognized and agreed that  budgeting will be done on a monthly basis;  however,
invoicing and  calculation  of cost overruns will be done on a calendar  quarter
basis. The initial budget against which NeoRx may commence incurring expenses is
included in the  Development  Plan.  After the first  Marketing  Approval in the
United  States,  NeoRx shall have no obligation to provide FTEs or perform other
activities  with  respect to  Development  of a Primary  Pre-Targeting  Product,
unless the Parties  mutually agree to a compensation  arrangement  for NeoRx for
such services.

2.3      Development Committee

         In  order  to  coordinate  activities  between  Janssen  and  NeoRx,  a
Development  Committee shall be promptly  established  after the Effective Date.
The Development  Committee shall be comprised of representatives from each Party
with the size of the Development Committee to be agreed upon by the Parties from
time to time. The purpose of the  Development  Committee shall be to monitor the
Development of each  Pre-Targeting  Product,  facilitate the flow of Information
with respect to  Development  being  conducted for each  Pre-Targeting  Product,

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                                       12
<PAGE>

oversee the preparation of any revised Development Plans,  including Development
timelines, and submit Development Plans to the Janssen Research Management Board
for review and  budget  approval.  Any  disputes  that arise at the  Development
Committee shall be discussed by the president of the Janssen Research Foundation
or its successor organization and the president of NeoRx. If the two individuals
cannot  resolve the dispute after good faith  discussions,  the president of the
Janssen Research  Foundation or its successor  organization shall make the final
decision.  It is recognized  and agreed that the  Development  Committee  cannot
change the  rights or  obligations  of the  parties  under this  Article II with
respect to research and Development.

2.4      Additional Products

         Both   Janssen  and  NeoRx  shall  be  involved  in  the  research  and
Development  of  Additional  Products  based on the  then-current  expertise and
resources  of both  Parties.  In case Janssen  decides to develop an  Additional
Product,  both Parties shall discuss how they can best capitalize on their joint
expertise  in  the  Field  and  determine  resources.   To  the  extent  of  its
participation,  NeoRx shall receive full  reimbursement of its Development Costs
(including FTEs) from Janssen, such participation being similar to the extent it
has  participated  to date and is expected to  participate  in the future in the
research and Development of the Primary Pre-Targeting Product.  Janssen shall be
responsible  for all  regulatory  filings  in  connection  with such  Additional
Products.  In  developing  Additional  Products,  Janssen  shall use  reasonable
efforts  consistent  with its normal  business  practices.  In carrying  out its
activities,  NeoRx  shall use  reasonable  efforts  consistent  with its  normal
business practices.

2.5      FDA

         NeoRx  shall have right to  participate  as an  observer in any planned
meetings  (whether by phone,  video  conferencing,  face-to-face  or  otherwise)
between Janssen (or its Affiliates or sublicensees)  and the FDA with respect to
regulatory  matters  pertaining to  Pre-Targeting  Products.  Janssen shall give
sufficient  advance  notice to NeoRx,  to the  extent  possible,  to allow it to
observe such meetings.  It is recognized that there are some circumstances where
it may be  impractical  to include NeoRx as an observer  (e.g.,  acute  toxicity
reports and encounter at conferences),  but the intention is, whenever possible,
to allow NeoRx to participate  as an observer.  At its  discretion,  Janssen may
allow  NeoRx to  participate  actively  in such  meetings.  NeoRx  shall have an
opportunity to review all documents and filings with the FDA, and communications
from the FDA.


                                       13
<PAGE>


2.6      IND Transfer

         NeoRx  agrees to  promptly  transfer  and assign any IND or  equivalent
foreign regulatory filing relating to a Pre-Targeting  Product that it has filed
prior to the Effective Date upon written request from Janssen.

2.7      Research Audit

         NeoRx will  maintain  complete  and  accurate  records  relevant to its
expenditure  of  Development  funding  provided  to it by  Janssen  pursuant  to
Paragraphs  2.2 and 2.4. Such records shall be open during  reasonable  business
hours for a period of three (3) years from  creation of the  individual  records
for examination, at Janssen's expense and not more often than once each year, by
an independent  certified public accountant  appointed by Janssen and reasonably
acceptable  to NeoRx for the  purpose of  verifying  for  Janssen the use of the
funding.  Such  accountant may retain or utilize  independent  consultants  with
expertise  necessary to assist such  accountant  in  examining  such records and
making such determination.

2.8      Capital Expenditures

         NeoRx shall not be required  to purchase  any item of a capital  nature
reasonably  required by NeoRx to conduct Development unless it is covered by the
budget  or  otherwise  approved  by  Janssen,  in  which  event  NeoRx  shall be
reimbursed by Janssen.  For the purpose of this  Paragraph  2.8, the term "item"
refers to a complete  operational  unit or a related  group of cell  lines.  For
example,  if the instrument being purchased  requires the purchase of a computer
(including the acquisition,  by license or otherwise,  of computer  software) to
run the instrument, the operational unit is the combination of the two.

         All purchases or  acquisitions of capital items that cost [ * ] or more
shall be to the account of Janssen; provided,  however, that Janssen approves in
advance each such purchase or acquisition.  The determination of whether Janssen
purchases  or acquires an item  exceeding [ * ] or NeoRx  purchases  or acquires
such item and is reimbursed by Janssen shall be made by the Parties prior to the
purchase.  Any items  purchased  or  otherwise  acquired and charged one hundred
percent (100%) to Janssen's account shall be solely owned by Janssen, maintained
and insured at Janssen's  expense and, if not consumed  during the  development,
transferred to Janssen,  at its expense, by NeoRx upon termination or expiration
of this Agreement.

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<PAGE>


                               III. LICENSE GRANTS

3.1      License for Pre-Targeting Products

         Subject to the terms of this Agreement,  NeoRx hereby grants to Janssen
an exclusive, worldwide right and license under NeoRx Patents and NeoRx Know-How
to  develop,   make,  have  made,  use,  sell,  have  sold  and  distribute  any
Pre-Targeting  Products in the Field. NeoRx shall not knowingly do anything that
would  jeopardize  Janssen's  ability to obtain  exclusive  rights to a specific
Pre-Targeting Product in the Crossover Field prior to [ * ].

3.2      Sublicense Rights

         The right and license  granted under Paragraph 3.1 with respect to each
Pre-Targeting  Product shall be sublicensable by Janssen to a Third Party in any
country; provided,  however, that Janssen shall not have the right to sublicense
the Development of the entire Pre-Targeting  Product to any one Third Party, but
nevertheless  shall  have the right to  sublicense  for  development  individual
components of the Pre-Targeting Product to Third Parties with no one Third Party
having a license to develop all of the components.

3.3      Distribution

         Janssen  may sell or  distribute  Pre-Targeting  Products  through  its
Affiliates or distributors in any country.

3.4      Nonexclusive Know-How License to NeoRx

         Janssen  hereby  grants  to NeoRx a  paid-up,  nonexclusive,  worldwide
license  to use  Janssen  Know-How  (except  compounds,  assays  and  biological
materials),  with the right to sublicense, and to disclose such Janssen Know-How
subject to a binder of  confidentiality  so long as the provisions of Article XI
remain in effect.

3.5      Nonexclusive Know-How License to Janssen

         NeoRx  hereby  grants to  Janssen a  paid-up,  nonexclusive,  worldwide
license  to use NeoRx  Know-How  (except  compounds,  assays,  Clearing  Agents,
Ligand/Anti-Ligand Pairs and biological materials, including NR-LU-10), with the

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                                       15
<PAGE>

right to sublicense,  and to disclose such NeoRx Know-How  subject to the binder
of confidentiality so long as the provisions of Article XI remain in effect.

3.6      Third-Party Agreements

         Janssen shall comply with and perform in accordance with all agreements
under  which  NeoRx has Control of NeoRx  Pre-Targeting  Technology.  If Janssen
intends to have another party  manufacture any  Pre-Targeting  Product,  Janssen
shall  first  negotiate  in good faith with [ * ]. In the event that  Janssen or
NeoRx  takes a direct  license  to any  Third  Party  Patents,  it shall use its
reasonable  and  diligent  efforts to provide in such license that (a) the other
Party  shall be  granted a  sublicense  with the same  scope and (b) upon  early
termination of such license, the other Party shall have a right to take over the
license as a direct license upon the same terms, provided the other Party agrees
to comply  with the  terms and to pay the  licensor  any past due  milestone  or
royalty payments that the licensor has identified as unpaid.

3.7      No Other Rights

         All rights and licenses not specifically  granted to Janssen under this
Agreement by NeoRx are hereby reserved and retained by NeoRx.

3.8      Prohibition

         Except as  licensed  hereunder,  Janssen  shall not use,  and shall not
allow its  Affiliates  and  sublicensees  to use,  the NeoRx  Patents  and NeoRx
Know-How for any other purpose.

                                  IV. PAYMENTS

4.1      Upfront Payments

         Janssen  shall  pay or cause to be paid to NeoRx  Ten  Million  Dollars
($10,000,000) as follows:

         (a)......Five  Million  Dollars  ($5,000,000)  within  ten (10) days of
receiving  an  invoice  (which  invoice  may be dated  and  delivered  as of the
Effective Date) and

         (b)......Five  Million Dollars  ($5,000,000) as an equity investment in
[Convertible Preferred Stock or Common Stock] of NeoRx pursuant to the terms and

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                                       16
<PAGE>

conditions of a Stock Purchase  Agreement between Johnson & Johnson  Development
Corporation and NeoRx dated as of the Effective Date.

4.2      Milestone Payments for the First Pre-Targeting Product

         Janssen shall pay NeoRx the following amounts for the first achievement
of each of the following milestones by any Pre-Targeting Product:

         [   *   ]

         All milestone  payments  recited in this Paragraph 4.2 shall be payable
only once.  Once a particular  milestone  has been paid it will not be due again
for a replacement or follow-up  product,  so that the total  milestones  payable
under this Paragraph 4.2 shall not exceed [ * ].

         No credits from or against any royalties  hereunder  shall be available
on any of the milestones recited in this Paragraph 4.2.

         Janssen shall promptly notify NeoRx of the occurrence of each milestone
event.  Each milestone  payment shall be due and payable after such notification
and shall be paid no later than  thirty  (30) days  after  receipt of an invoice
from NeoRx.

4.3      Milestones for a Second Type of Pre-Targeting Product

         In addition to the milestone payments recited in Paragraph 4.2, Janssen
shall pay NeoRx the following amounts for the second Pre-Targeting  Product that
achieves  the  following  milestones  and that is of a different  type than that
Pre-Targeting  Product  that  achieved the same  milestone  in Paragraph  4.2 (a
"type" of Pre-Targeting  Product being either a Primary Pre-Targeting Product or
an Additional Product):

         [   *   ]

         For example,  if the milestones set forth in Paragraphs  4.2(a) and (b)
were first  achieved by a Primary  Pre-Targeting  Product and the  milestone set
forth in  Paragraph  4.2(c) was first  achieved by an  Additional  Product,  the
milestones set forth in Paragraphs  4.3(a) and (b) would not be triggered unless
achieved  by  an  Additional  Product  and  a  Primary  Pre-Targeting   Product,
respectively.

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<PAGE>


         All milestone  payments  recited in this Paragraph 4.3 shall be payable
only once.  Once a particular  milestone  has been paid it will not be due again
for a replacement or follow-up  product,  so that the total  milestones  payable
under this Paragraph 4.3 shall not exceed [ * ].

         No credits from or against any royalties  hereunder  shall be available
on any milestones recited in this Paragraph 4.3.

         Janssen  shall  promptly   notify  NeoRx  of  the  occurrence  of  each
milestone.   Each  milestone  payment  shall  be  due  and  payable  after  such
notification  and shall be paid no later than thirty (30) days after  receipt of
an invoice from NeoRx.

4.4      Earned Royalties for Primary Pre-Targeting Products

         Janssen shall pay NeoRx a royalty based on Net Sales in connection with
the annual Net Sales of each  Primary  Pre-Targeting  Product  by  Janssen,  its
Affiliates and sublicensees as follows:

           Royalty Rate                           Worldwide Net Sales (annual)

           [   *   ]                              [   *   ]

           [   *   ]                              [   *   ]

         For example, if during a year of sales,  Janssen has Net Sales of [ * ]
of a Primary  Pre-Targeting  Product,  Janssen is obligated to pay  royalties as
follows: [ * ] and [ * ].

4.5      Royalty Adjustment in U.S. for Primary Pre-Targeting Products

         In the  United  States  only,  NeoRx  will  share in the  gross  profit
increase/decrease  resulting from changes in the Cost of Goods Sold structure of
the Targeting Agent and Clearing Agent  components of the Primary  Pre-Targeting
Product being sold as recited hereinafter.  An annual adjustment only to the [ *
] royalty rate shall be made by calculating  the percentage  change to the [ * ]
royalty rate (the [ * ] royalty rate shall not likewise be so adjusted) based on
Actual Cost of Goods  Percentage  changes  (excluding Third Party Royalties) and
Third Party Royalty Rate changes according to the following formula:

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         [   *   ]

wherein AR is the adjusted royalty rate; provided, however, that AR can never be
greater  than [ * ] or less  than [ * ] and AR1  and AR2 are  calculated  as set
forth in clauses (a) and (b) below.

         (a)......Royalty Rate Adjustment for Actual Cost of Goods Percentage
Changes (Excluding Third Party Royalty Rates).

         If the Actual Cost of Goods Percentage  ("A1") for any calendar year is
greater  than or less  than  the  Standard  Cost of Goods  Reference  Percentage
("S1"), then AR1 shall be calculated according to the following formula:

         [   *   ]

wherein A1 is calculated  by dividing the average Cost of Goods Sold  (excluding
Third Party Royalty  Rates) per dose by an amount (the "Per Dose Price") that is
the  greater of (i) [ * ] and (ii) the  average Net Sales per dose in the United
States for the calendar  year, and S1 is calculated by dividing [ * ] by the Per
Dose  Price;  provided,  however,  that in the event the  average  dose does not
contain [ * ] of chemical  conjugate,  fusion protein or other  Targeting  Agent
bound to Avidin,  the [ * ] shall be adjusted using the  calculational  approach
set forth in the  December 4, 1996 letter from  Patrick  Verheyen to Paul Abrams
attached hereto as Exhibit D.

         (b)......Royalty Rate Adjustment Based on Changes to Third Party 
Royalty Rates.

         If the actual  cumulative  Third Party  Royalty  Rate ("A2") is greater
than or less than the Standard Cumulative Third Party Royalty Rate ("S2"), which
equals [ * ], then AR2 shall be calculated according to the following formula:

         [   *   ]

wherein A2 is the actual  cumulative Third Party Royalty Rate paid to such Third
Parties   during  the  calendar  year  with  respect  to  the  sale  of  Primary
Pre-Targeting Products in the United States and S2 equals [ * ].

         For example, if the average Cost of Goods Sold for a calendar year is 
[ * ] per dose [ * ] and the average Net Sales per dose for the same calendar

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<PAGE>


 
year are [ * ] per  dose,  A1 equals [ * ]. If the Actual Cumulative Third Party
Royalty Rate is [ * ], then using the formulas shown above:

         [   *   ]

         Should the  adjusted  royalty rate  calculation  result in monies being
owed to NeoRx as in the above example,  Janssen shall report to NeoRx the amount
of monies  owed and,  upon  receipt of an invoice  from  NeoRx,  shall pay NeoRx
within  thirty (30) days after receipt of invoice.  Should the adjusted  royalty
rate  calculation  result in monies  being owed to Janssen,  Janssen  shall take
those monies as a credit on the next scheduled royalty payment to NeoRx.

4.6      Earned Royalties for Additional Products

         Janssen shall pay NeoRx a royalty based on Net Sales in connection with
the annual Net Sales of each Additional  Product by Janssen,  its Affiliates and
sublicensees as follows:

         Royalty Rate                       Worldwide Net Sales (annual)

         [   *   ]                                   [   *   ]

         [   *   ]                                   [   *   ]

4.7      Royalty Adjustment in U.S. for Additional Products

         The royalty  rates recited in Paragraph 4.6 are based on an Actual Cost
of Goods  Percentate  plus the Third Party  Royalty Rate being [ * ] or less for
the United  States.  If on an annual  basis the Actual Cost of Goods  Percentage
plus the Third Party  Royalty is greater than [ * ] for the United  States,  the
royalty rates for the United States shall be as follows:

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         Royalty Rate                       Worldwide Net Sales (annual)

         [   *   ]                                            [   *   ]

         [   *   ]                                            [   *   ]

4.8      Duration of Royalty Payments

         The  royalties  recited in  Paragraphs  4.4 and 4.6 shall accrue and be
payable on a country-by-country and product-by-product basis with respect to Net
Sales occurring prior to the later of (a) the last to expire of any NeoRx Patent
with a Valid Claim covering the Pre-Targeting Product or its use or (b) ten (10)
years from the Date of First Sale of the  Pre-Targeting  Product in the country,
except that the Date of First Sale for any country in the  European  Union shall
be deemed to be, if earlier,  the first Date of First Sale of the  Pre-Targeting
Product in a Major European Market  Country.  Thereafter,  no further  royalties
shall accrue and the license  under  Paragraph  3.1 shall  become fully  paid-up
(except for  payments to Third  Parties) and  non-exclusive  with respect to the
Pre-Targeting Product and country.

4.9      Reduction in Royalty Rate in Response to Generic Competition

         Except as provided in  Paragraph  4.21,  the royalty  rates  recited in
Paragraphs  4.4  and  4.6  shall  be  reduced  (on  a   country-by-country   and
product-by-product   basis)  by  [  *  ]  in  connection  with  the  sale  of  a
Pre-Targeting  Product by  Janssen,  its  Affiliates  or  sublicensees  in those
countries  where (a) the royalty  period  described in Paragraph  4.8(b) has not
expired and the royalty  period  described  in  Paragraph  4.8(a) has either (i)
expired or (ii) is still  running  only as a result of a Valid  Claim in a NeoRx
Patent covering only a method of manufacturing the Pre-Targeting  Product, (b) a
Generic Product to the Pre-Targeting  Product is being  manufactured and sold in
the country without  infringing such Valid Claim, and (c) the total sales of the
Generic Product in the country are  cumulatively [ * ] of the total sales of the
Pre-Targeting Product being sold hereunder expressed in equivalent units in said
country for a [ * ]. Once it has been  determined that  competition  exists in a
particular  country pursuant to clause (c) of this paragraph and clauses (a) and
(b) of this paragraph apply, the royalty rates shall be reduced pursuant to this

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<PAGE>

Paragraph 4.9 for the next  succeeding [ * ], and the  determination  of whether
competition continues to exist shall be reviewed [ * ] thereafter. If for such [
* ] competition  exists,  then the royalty  rates for the next  succeeding [ * ]
shall  continue to be as set forth in this  Paragraph  4.9. If it is  determined
that  competition   exists  for  [  *  ],  the  royalty  for  such  country  and
Pre-Targeting Product shall be as set forth in this Paragraph 4.9, unless it can
be  demonstrated  that no  competition  pursuant to clause (c) of this paragraph
exists for [ * ].

4.10     Reduction in Royalty Rate in Response to Substitute Product Competition

         Except as provided in  Paragraph  4.21,  the royalty  rates  recited in
Paragraphs  4.4  and  4.6  shall  be  reduced  (on  a   country-by-country   and
product-by-product   basis)  by  [  *  ]  in  connection  with  the  sale  of  a
Pre-Targeting  Product by  Janssen,  its  Affiliates  or  sublicensees  in those
countries where (a) a Substitute  Product to the Pre-Targeting  Product is being
sold and (b) the  total  sales  of the  Substitute  Product  in the  country  is
cumulatively  at least [ * ] of the  total  sales of the  Pre-Targeting  Product
being sold hereunder  expressed in equivalent  units in said country [ * ]. Once
it has been determined that competition  exists in a particular country pursuant
to clause (b) of this  paragraph and clause (a) of this paragraph  applies,  the
royalty  rates  shall be reduced  pursuant to this  Paragraph  4.10 for the next
succeeding  [ * ], and the  determination  of whether  competition  continues to
exist shall be reviewed [ * ] thereafter.  If for such [ * ] competition exists,
then the royalty rates for the next succeeding [ * ] shall continue to be as set
forth in this Paragraph 4.10. If it is determined that competition  exists for [
* ], the royalty  for such  country and  Pre-Targeting  Product  shall be as set
forth in this Paragraph 4.10,  unless it can be demonstrated that no competition
pursuant to clause (b) of this paragraph exists for [ * ].

4.11     Reduction in Royalty Rate for Jointly Owned Patents

         After the  expiration  of the royalty  period  described  in  Paragraph
4.8(b) and except as provided in Paragraph  4.21,  the royalty  rates recited in
Paragraphs  4.4  and  4.6  shall  be  reduced  (on  a   country-by-country   and
product-by-product  basis) [ * ] in connection  with the sale of a Pre-Targeting
Product by Janssen,  its Affiliates or sublicensees in those countries where the
only Valid  Claim(s)  covering the  Pre-Targeting  Product are in jointly  owned
patents described in Paragraph 8.3 that were filed in good faith more than [ * ]
after the Effective Date.

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<PAGE>


4.12     Foreign Exchange

         The  remittance  of  royalties  payable on Net Sales will be payable in
U.S.  dollars to NeoRx at a bank and to an account  designated  by NeoRx using a
rate of exchange of the  currency of the country  from which the  royalties  are
payable in  accordance  with the rate of exchange  published  in The Wall Street
Journal as of the last business day of the month immediately preceding the month
during  which  payment  of such  royalties  is  required  to be  made  to  NeoRx
hereunder. All references to "Dollars" hereunder are references to U.S.
Dollars.

4.13     [Intentionally Left Blank]

4.14     Taxes

         All payments under this Agreement will be made without any deduction or
withholding for or on account of any tax unless such deduction or withholding is
required by any applicable law. If Janssen is so required to deduct or withhold,
Janssen will:

         (a)......promptly notify NeoRx of such requirement;

         (b)......pay to the relevant authorities the full amount required to be
deducted  or  withheld  promptly  upon the  earlier  of  determining  that  such
deduction or  withholding  is required or receiving  notice that such amount has
been assessed against NeoRx; and

         (c)......promptly  forward to NeoRx an official  receipt (or  certified
copy), or other documentation  reasonably  acceptable to NeoRx,  evidencing such
payment to such authorities.

         In case such  deduction or  withholding  is  required,  the Parties may
propose  changes to the then  current  arrangement  with  respect to the flow of
monies under this  Agreement in order to reduce or eliminate  the extra cost for
NeoRx.

         All payments pursuant to Paragraphs 4.1, 4.2, 4.3, 4.4, 4.6 and 4.19 to
NeoRx shall be made by Janssen from either Belgium or the United States so that,
under current law, there should be no tax withholding.

4.15     Records, Reports and Payment

         Janssen  shall  keep  complete  and  accurate  records  of the  sale of
Pre-Targeting  Products, with respect to which a royalty is payable according to
this  Agreement.  Within thirty (30) days following  each quarterly  period of a



                                       23
<PAGE>

calendar year,  Janssen shall render to NeoRx a written report setting forth the
Net Sales (in local currency and U.S.  Dollars,  with applicable  exchange rates
pursuant to  Paragraph  4.12 noted) and quantity of such  products  sold and the
royalty due and payable on a  product-by-product  and  country-by-country  basis
(including  all deductions  taken from the gross sales price in determining  Net
Sales and any royalty reduction or credit). NeoRx shall then remit to Janssen an
invoice for the royalty  payment due and Janssen shall,  within ten (10) days of
receipt of such  invoice,  remit to NeoRx the amount of royalty shown thereby to
be due.

4.16     Accounting

         Each  Party  shall have the right,  at its own  expense,  to appoint an
independent certified public accountant reasonably acceptable to and approved by
the other Party, said approval not to be unreasonably  withheld or delayed,  who
shall have access to the other Party's records during reasonable  business hours
for the purpose of verifying Net Sales,  the Cost of Goods Sold, the Actual Cost
of  Goods  Percentage,   Third-Party  Royalty  Rates,  manufacturing  costs  and
supplier's  charges  (Paragraphs  5.6 and 7.2) and the  calculation of royalties
payable for any period within the  preceding  three (3) years or, in the case of
Janssen,  for verifying  whether NeoRx dedicated the number of FTEs for which it
received  funding at the rate  agreed to  pursuant to Article II. This right may
not be exercised more than once in any calendar year, and said accountant  shall
disclose to the Party requesting the audit only  information  relating solely to
the  accuracy  of  the  royalty  report,   the  royalty   payments  or  research
expenditures  according to this  Agreement.  If any audit or  examination  shall
reveal a  deficiency  of any royalty  payment  due,  the Party owing the royalty
shall make payment to the other Party of such  deficiency  plus interest for the
period of such deficiency.  If any audit or examination  shall reveal that NeoRx
has not  properly  spent  the  research  funding  pursuant  to the terms of this
Agreement and therefore misused such funding,  NeoRx shall refund any monies not
so properly spent to Janssen.  Payment of such  deficiencies or misused research
funding shall be made within five (5) days following written notification of the
auditing  Party to the Party being audited of the monies owed. In the event that
such an audit or  examination  shall reveal a deficiency of any royalty  payment
due in an amount  equaling or exceeding  five  percent (5%) of the  royalties or
expenditures, the Party shall reimburse the other Party for the reasonable costs
of such audit within ten (10) business days after written demand therefor.



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<PAGE>


4.17     Third Party Patents

         If a patent or patents of a Third Party, other than Third Party Patents
or patents [ * ], should exist in any country  during the term of this Agreement
covering the use or sale of any Primary Pre-Targeting Product comprised of a [ *
], and if it  should  prove in  Janssen's  reasonable  judgment  impractical  or
impossible  for Janssen or any Affiliate or sublicensee to continue the activity
or activities  licensed  hereunder without  obtaining a royalty-bearing  license
from such Third Party under such patent or patents in said country, then, except
as provided in  Paragraph  4.21,  Janssen  shall be entitled to a credit for the
royalty  paid to such Third Party under such  license for the use or sale of the
Primary  Pre-Targeting  Product in said country  ("Royalty"),  such credit being
applied against only the royalty  payments due under this Agreement with respect
to the Primary  Pre-Targeting Product for said country and in an amount equal to
[ * ] of the  Royalty  paid to such Third  Party;  provided,  however,  that the
earned  royalties  payable to NeoRx under this Agreement shall not be reduced to
less  than [ * ] of Net  Sales of such  Primary  Pre-Targeting  Product  in said
country  by  reason  of the  credit  described  in this  Paragraph  4.17 and the
reduction  provided by this  Paragraph  4.17 with  respect to the United  States
shall not  exceed [ * ] of the amount by which [ * ] the  Royalty  exceeds [ * ]
for the United States. For example, with respect to such a Primary Pre-Targeting
Product  in the  United  States,  if A1  equals  [ * ], A2  equals [ * ] and the
Royalty  equals [ * ],  then  the  maximum  amount  of the  Royalty  that may be
deducted  pursuant to this  Paragraph 4.17 from the earned  royalties  otherwise
payable on Net Sales in the United States for such Primary Pre-Targeting Product
shall not exceed [ * ] and shall not be  applied to reduce the earned  royalties
payable to NeoRx to less than [ * ] of Net Sales in the  United  States for such
Primary Pre-Targeting Product. (Note that by operation of Paragraph 4.5, without
the  application of this Paragraph  4.17, the earned royalty rate may be reduced
to [ * ].)

4.18     Compulsory License

         If at any  time  and from  time to time a Third  Party  in any  country
shall,  under the right of a compulsory license granted or ordered to be granted
by a competent  governmental  authority,  sell any Pre-Targeting  Product,  with
respect to which royalties would be payable  pursuant to Paragraphs 4.4 and 4.6,
then  except as provided in  Paragraph  4.21,  Janssen may reduce the royalty on
sales in such  country of such  Pre-Targeting  Product,  to an amount no greater

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<PAGE>

than the amount payable by said Third Party as consideration  for the compulsory
license;  provided,  however, that the royalty rate payable by Janssen after any
reduction  thereof  pursuant to this Paragraph 4.18 shall not be less than [ * ]
of Net Sales of such Pre-Targeting Product in such country.

4.19     No Multiple Royalties; Third Party Royalties

         If a Pre-Targeting  Product is covered by more than one license granted
hereunder, Janssen shall be responsible for payment of only one royalty based on
the Net  Sales  thereof,  such  royalty  to be equal to the  highest  applicable
royalty rate on a product-by-product  and  country-by-country  basis;  provided,
however,  that  Janssen  shall  remain  responsible  for paying all Third  Party
Royalties and any other royalties or amounts that NeoRx owes or has paid a Third
Party for NeoRx  Pre-Targeting  Technology that it hereafter acquires Control of
and that Janssen elects to have included in the license granted in Paragraph 3.1
and added to the  definition(s) of NeoRx Patents and/or NeoRx Know-How.  Janssen
shall pay such Third Party Royalties and other royalties or amounts to NeoRx or,
at NeoRx's request, directly to the appropriate Third Party.

4.20     Value of Collaboration in NeoRx Know-How

         Janssen acknowledges that NeoRx's participation and work in Development
may be of substantial value and that the NeoRx Know-How and/or NeoRx's rights to
NR-LU-10 may constitute  valuable and  substantial  trade secrets of NeoRx.  The
parties  acknowledge  and agree that,  for their  mutual  convenience  and after
considering other alternatives,  including  reimbursement of NeoRx's costs under
Paragraph 2.2 and larger or other upfront and milestone  payments,  the payments
to NeoRx  set  forth in this  Agreement,  including  the  structure  and term of
royalty payments, are an appropriate and mutually convenient way of compensating
NeoRx.

4.21     No Multiple Reductions

         Notwithstanding  the provisions of Paragraphs 4.9, 4.10, 4.11, 4.17 and
4.18  (each  a  "Royalty  Reduction  Paragraph"),  only  one  Royalty  Reduction
Paragraph  may be  applied  to reduce  the  royalty  obligations  payable  under
Paragraphs  4.4 (as adjusted by Paragraph 4.5) and 4.6 (as adjusted by Paragraph
4.7) and the reductions provided by the other Royalty Reduction Paragraphs shall
not be  accumulated  and shall be lost.  With each  quarterly  report  due under
Paragraph  4.15,  Janssen  shall  identify  which,  if  any,  Royalty  Reduction

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Paragraph  it  elects  to apply to the  royalties  due on the Net  Sales for the
quarter.

4.22     Allocation of Annual Net Sales [   *   ]

         In the event annual worldwide Net Sales [ * ] (the "Breakpoint") and it
is  necessary  to treat Net  Sales for  certain  Pre-Targeting  Products  and/or
countries differently (e.g., under Paragraphs 4.5, 4.7, 4.9, 4.10, 4.11, 4.17 or
4.18),  then the  amount  of Net  Sales for such  Pre-Targeting  Product  and/or
country  that are  deemed to be above the  Breakpoint  (i.e.,  to which a higher
royalty rate is applied  under this  Agreement)  shall be equal to the worldwide
annual  Net  Sales in [ * ]  multiplied  by the  ratio of the Net Sales for such
Pre-Targeting  Product  and/or  country to the worldwide  annual Net Sales;  the
balance of such Net Sales  being  deemed to be below the  Breakpoint  (i.e.,  to
which a lower royalty rate is applied).  Any credits to royalties provided under
Paragraph  4.17 for a particular  Pre-Targeting  Product and/or country shall be
attributed  prorata to the  royalties for Net Sales deemed to be above and below
the  Breakpoint,   i.e.,  if  one-third  of  the  Net  Sales  for  a  particular
Pre-Targeting Product and/or country is deemed to be above the Breakpoint,  then
one-third of the credit for such  Pre-Targeting  Product and/or country shall be
deemed  attributable  to the higher  royalty rate and  two-thirds  of the credit
shall be deemed attributable to the lower royalty rate.

         For example, if worldwide Net Sales of a Primary  Pre-Targeting Product
are [ * ] in one year,  of which [ * ] are in the United States and [ * ] are in
the rest of the world,  and if the adjusted  royalty rate on the first [ * ] Net
Sales  in the  United  States  is [ * ]  pursuant  to  Paragraph  4.5,  then the
aggregate  royalties payable to NeoRx pursuant to Paragraphs 4.4 and 4.5 for the
year on such Net Sales would be [ * ],  calculated  as follows:  with respect to
the United States, [ * ]; and, with respect to the rest of the world, [ * ].

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         V. JANSSEN'S OPTION TO EXPAND FIELD AND INDEPENDENT DEVELOPMENT

5.1      Janssen's Option to Expand the Field

         Until [ * ] after the Effective Date,  Janssen shall have the exclusive
right and  option to expand  the  Field to [ * ];  provided,  however,  that the
Parties agree on financial terms and conditions during such [ * ]. If either (a)
the  Parties  fail to reach  agreement  by the end of such [ * ] or (b)  Janssen
notifies  NeoRx  during such [ * ] that it elects not to exercise  its right and
option, the right and option shall be terminated.

5.2      Exercise of Janssen's Option

         Janssen  shall be deemed  to have  exercised  its  right and  option to
expand the Field pursuant to Paragraph 5.1 upon written agreement by the Parties
to the financial terms and conditions.

5.3      Limitation on NeoRx Right to Assign or License Prior to Exercise by 
Janssen of Its Option

         NeoRx agrees not to assign or license any rights in the expanded  Field
as defined in  Paragraph  5.1 (or begin  discussions  with any Third Party to do
such) until the first to occur of:

         (a)......Janssen exercises its option to expand the Field pursuant to 
Paragraph 5.2;

         (b)......Janssen elects not to exercise its option; or

         (c)......The option period expires without Janssen exercising its 
option.

5.4      NeoRx Right to Independently Develop Pre-Targeting Products Within the
Field

         At any time  following  [ * ], but not more than  once  every [ * ] and
with  not more  than [ * ] such  recommendations  in the  aggregate,  NeoRx  may
propose a  Pre-Targeting  Product,  other than  Avicidin or other  Pre-Targeting
Product in Development or on sale hereunder, as a Pre-Targeting Product to enter

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<PAGE>

into  development  by written notice to Janssen after NeoRx has completed [ * ].
Together with its notice, NeoRx will submit a detailed proposed development plan
and a  proposed  development  budget  for the  proposed  Pre-Targeting  Product.
Janssen shall have one hundred twenty (120) days from the date of receipt of the
notice,  together with the proposed  development  plan and budget,  to accept or
reject  NeoRx's  recommendation  to  commence  development.  If Janssen  accepts
NeoRx's  recommendation to develop the proposed  Pre-Targeting Product, it shall
so notify NeoRx within the one hundred  twenty (120) day period and shall assume
responsibility  for development  pursuant to Article II. If Janssen either fails
to  notify   NeoRx  of  its  decision  to  either   accept  or  reject   NeoRx's
recommendation within the one hundred twenty (120) day period or rejects NeoRx's
recommendation  within  the one  hundred  twenty  (120)  day  period,  NeoRx may
independently develop the proposed Pre-Targeting  Product,  subject to the right
to re-offer it to Janssen  under  Paragraph  5.5;  provided,  however,  that the
proposed  Pre-Targeting  Product is not being  developed for the same indication
for which a Pre-Targeting Product is being developed or marketed hereunder.  The
proposed  Pre-Targeting Product shall be an Independent Product until and unless
Janssen elects,  pursuant to Paragraph 5.4 or 5.5, to have it developed pursuant
to Article II, in which event it shall become a Pre-Targeting  Product for which
milestone payments may be payable pursuant to Paragraph 4.2 or 4.3.

5.5      NeoRx Obligation to Re-Offer

         In  the  event  that  NeoRx  continues  to  independently  develop  the
Independent  Product,  NeoRx  agrees  that it will  disclose  a  summary  of all
development  plans,  results  and data every six (6) months  during  independent
development to Janssen through the Development Committee and re-offer in writing
the Independent Product to Janssen at least [ * ] prior to the estimated date of
[ * ]. The  Development  Committee  shall be involved in the development of such
Independent  Product to the extent necessary to assure that its development does
not interfere with or disrupt the  Development of any  Pre-Targeting  Product in
Development. The re-offer of the Independent Product to Janssen shall include at
the time of  re-offer a complete  information  package on  development  results,
plans and data, details of monies expended, and a comprehensive development plan
and budget, all of which shall be kept updated during the re-offer period.

         Upon a  re-offer,  Janssen may elect that such  Independent  Product be
returned to it for  development  under this Agreement by notifying  NeoRx (a) at

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<PAGE>

any time prior to the [ * ] or (b) [ * ] following  the  re-offer,  whichever is
the later.  At the time such  Independent  Product is  returned  to Janssen  for
Development,  Janssen shall pay NeoRx [ * ] of the  Development  Costs that were
incurred  independently  by NeoRx for the Independent  Product up to that point,
plus  accrued  simple  interest at the prime rate plus [ * ] adjusted  quarterly
during the period of independent development.

         If Janssen elects to cause an Independent  Product to be returned to it
for  Development,  it shall  cease  being an  Independent  Product  and become a
Pre-Targeting  Product for which milestone  payments may be payable  pursuant to
Paragraph 4.2 or 4.3.

         If  Janssen  does not elect to cause  such  Independent  Product  to be
returned to it within the time period  specified in this Paragraph 5.5, it shall
continue being an Independent Product and Janssen shall have no rights therein.

5.6      Limitations on NeoRx Rights During Re-Offer Period

         NeoRx  shall not  license  or  sublicense  its  rights  under any NeoRx
Patents or NeoRx  Know-How  with  respect  to any  Independent  Product  that is
subject to a re-offer right under Paragraph 5.5; provided,  however,  that NeoRx
shall  have the  right to  license  or  sublicense  rights to  manufacture  such
Independent  Product. In this regard, NeoRx shall be obligated to first offer to
Janssen  the right to  manufacture.  Janssen  shall have the  absolute  right to
manufacture  any  components  of such  Independent  Product that are the same or
substantially  the same as the  components  of a  Pre-Targeting  Product that is
being  developed by Janssen  hereunder.  With respect to components that are not
the same or substantially the same,  Janssen shall have the right to manufacture
such  components if it can  manufacture and supply to NeoRx the components at an
acceptable  quality  and at a  price  equal  to or  less  than  the  price  of a
qualified,  quality  manufacturer,  i.e., a manufacturer  that manufactures with
comparable  quality  as  Janssen  and is in  compliance  with  cGMPs  and  other
applicable regulatory  regulations and requirements.  Janssen shall exercise its
right to  manufacture  by giving its commitment in writing to NeoRx within [ * ]
of notice. If Janssen  manufactures  components for NeoRx and does not decide to
return the Independent Product to Development (i.e., decides not to exercise its
right of re-offer),  Janssen shall continue to manufacture NeoRx's  requirements
for such  components  for [ * ]. The price for  components  that are the same or

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<PAGE>

substantially   the  same  as  components   that  Janssen  is   developing   for
Pre-Targeting  Products shall be Janssen's  Cost of Goods Sold F.O.B.  Janssen's
facility  during the re-offer period and for [ * ] thereafter.  Thereafter,  the
price of such  components  shall be Janssen's  Cost of Goods Sold plus [ * ] for
the [ * ], and each year  thereafter  Janssen may  increase  the [ * ] number in
increments  of [ * ], so that in [ * ] the profit margin may be [ * ] and in 
[ * ], etc., subject to NeoRx's right to terminate such supply arrangements.

5.7      Janssen's Right of First Negotiation to Expand the Field Further

         In the event the Field has not been expanded pursuant to Paragraph 5.1,
in whole or in part,  Janssen  shall have the first  right of  negotiation  with
respect to the use of specific  antibodies in the Expansion Field prior to NeoRx
negotiating or entering into an agreement with a Third Party with respect to the
Expansion Field as follows: [ * ].

                                VI. CO-PROMOTION

6.1      Co-Promotion Option of NeoRx

         In connection with Pre-Targeting Products marketed and sold by or under
authority of Janssen hereunder,  NeoRx has the right to Co-Promote in the United
States  during  the term of this  Agreement  from the Date of First Sale of each
Pre-Targeting  Product  sold in the  United  States  according  to the terms and
conditions  recited in Paragraphs 6.2 - 6.17.  NeoRx's rights under this Article
VI shall only be transferable  pursuant to Paragraph  6.17.  NeoRx must indicate
its intention to Co-Promote by providing Janssen with notice within [ * ] of the
filing of a BLA for each Pre-Targeting Product; provided,  however, that Janssen
(or the Joint  Marketing and Sales Committee for  Pre-Targeting  Products (other
than the first one to be marketed))  provided to NeoRx,  at least [ * ] prior to
the date by which NeoRx must indicate its intention,  the proposed total Details
to be conducted for such  Pre-Targeting  Product in the United States,  together
with  a  complete  copy  of  the  then-current  U.S.  Marketing  Plan  for  such
Pre-Targeting  Product (to the extent one then  exists).  Should  NeoRx not have
been provided with such Information on or before the BLA filing, it shall have [
* ] from  receipt  of all  such  Information  to  indicate  its  intention.  The
notification  must include a  declaration  by NeoRx of what it commits to be its
effort for detailing to be used in refining the U.S.  Marketing Plan. Failure of
Janssen (or the Joint  Marketing  and Sales  Committee)  to provide the proposed
total Details along with a U.S. Marketing Plan will toll the time in which NeoRx
must decide to  Co-Promote  the  Pre-Targeting  Product.  Should  NeoRx elect to
Co-Promote  hereunder  and should  NeoRx not already have in place a sales force

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<PAGE>

suitable for  Co-Promoting,  Janssen may  instruct  NeoRx to begin to hire sales
professionals  to Co-Promote as early as [ * ] prior to the anticipated  Date of
First Sale for the Pre-Targeting  Product. NeoRx may only Co-Promote if within [
* ] after  Janssen  receives a letter from the FDA  approving  its Drug Approval
Application, it has in place in the United States an infrastructure,  including,
but not  limited  to,  reasonable  insurance  protection  and a sales  force  of
sufficient size to carry out the Details to which NeoRx has committed.  Promptly
following NeoRx's exercise of its right to Co-Promote each Pre-Targeting Product
hereunder, the Parties shall negotiate a more detailed Co-Promotion Agreement on
reasonable and customary terms and conditions, consistent with this Article VI.

6.2      Co-Promotion Limitation of Scope

         The scope of Co-Promotion for NeoRx will be limited specifically to its
representation  on the  Joint  Marketing  and Sales  Committee  and to carry out
Details to a target  audience,  which shall be determined by the Joint Marketing
and Sales Committee. The U.S. Marketing Plan shall set the Details for the [ * ]
of sale of each Pre-Targeting Product, taking into account NeoRx's commitment of
its detailing  support.  If NeoRx elects to Co-Promote a  Pre-Targeting  Product
under this Article VI, NeoRx shall have the right to conduct that  percentage of
Details  as equal up to [ * ], but not less than [ * ], of the total  Details to
be conducted for each  Pre-Targeting  Product during the period of Co-Promotion.
When making its commitment  under Paragraph 6.1, NeoRx must commit to a specific
percentage of total Details [ * ] range,  agreeing to carry out that  percentage
of the total  Details  during  each year of  Co-Promotion,  except to the extent
specified below.  After making its commitment to a specific  percentage of total
Details,  should the total  number of Details be changed by the Joint  Marketing
and Sales  Committee  for any future period  during the  Co-Promotion,  then the
actual number of Details assigned to NeoRx shall be changed as follows:

         (a)......If  the  percentage  change of total  Details  varies within a
range of [ * ] of the initial  number of total Details  established by the Joint
Marketing and Sales  Committee,  the total  Details  assigned to NeoRx shall not
change unless the Parties otherwise  mutually agree;  rather,  the Janssen sales
force shall be responsible for either making more or less Details,  whatever the
case may be.

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<PAGE>


         (b)......If the percentage  increase in total Details is greater than [
* ] of the initial number of total Details  established  by the Joint  Marketing
and Sales Committee,  NeoRx, at its option,  may increase its total Details by a
percentage  equal to its  initial  commitment  percentage  times the  percentage
increase  over the  initial  number of total  Details  established  by the Joint
Marketing and Sales Committee.  For example, if NeoRx initially committed to [ *
] of the total Details and the total Details  established by the Joint Marketing
and Sales Committee for [ * ] of the  Co-Promotion  amounted to a [ * ] increase
as  compared  to the initial  number of total  Details,  then NeoRx may elect to
increase  its total  Details by the  percentage  equal to [ * ], which is [ * ].
NeoRx must exercise its option to increase its total  Details by giving  Janssen
notice  within [ * ] of  being  notified  of the  percentage  increase  in total
Details or the option will terminate.

         (c)......If the percentage  decrease of total Details is greater than [
* ] of the initial number of total Details  established  by the Joint  Marketing
and Sales  Committee,  then NeoRx's total Details shall be decreased so that its
percentage of total Details remains at its initial commitment percentage.

         After NeoRx makes its commitment to a specific  number of Details,  the
Joint  Marketing and Sales Committee shall establish a target audience for NeoRx
to call on and a different  target audience for Janssen to call on. Depending on
marketing strategy, one or more target audiences to be called on by both Janssen
and NeoRx may also be established.

6.3      NeoRx Is Not a Distributor

         It is  recognized  by the  Parties  that  NeoRx,  under  its  option to
Co-Promote, may receive orders from Third Parties. NeoRx shall promptly transmit
said  orders to Janssen  and Janssen  shall book all sales  resulting  from such
orders.

6.4      Joint Marketing and Sales Committee

         The Joint Marketing and Sales Committee shall meet in the United States
at least four (4) times a year,  generally  on a quarterly  basis,  at Janssen's
facility or a  Janssen-designated  site, at mutually agreeable times, to discuss
and  coordinate  the  Co-Promotion  of  Pre-Targeting  Products  that are  being
Co-Promoted  by Janssen  and NeoRx in  accordance  with this  Agreement  and the
strategies  and programs  that should be  developed to optimally  grow each such
Pre-Targeting Product, including, but not limited to, the assignment of Details,

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                                       33
<PAGE>

designating the target audience and developing a U.S. Marketing Plan. Subject to
NeoRx's  prior  review and  opportunity  to comment,  Janssen will have the sole
responsibility,  with the  cooperation  and assistance of NeoRx,  for marketing,
pricing and promotion  strategies and all other  elements of the U.S.  Marketing
Plan with respect to each Pre-Targeting Product and budgets therefor. Allocation
of target  audiences  and  detailing  efforts  between  the Parties by the Joint
Marketing and Sales Committee will be done in a fair and reasonable  manner. All
disputes  relating  to  designating  the target  audiences  shall be resolved in
accordance with the procedures set forth in Paragraph 6.16.

6.5      Co-Promotion Obligations

         NeoRx and Janssen  shall use all  reasonable  efforts  consistent  with
Janssen's and NeoRx's normal business practices and legal requirements to deploy
a  professional  and  trained  sales  force to  Co-Promote  those  Pre-Targeting
Products  selected by NeoRx for  Co-Promotion  in the United  States.  NeoRx and
Janssen agree that their sales force employed in Co-Promoting each Pre-Targeting
Product,  shall be comprised of individuals at least [ * ] of whom have at least
[ * ] prior  pharmaceutical  sales experience (or is otherwise acceptable to the
other  Party),  and such sales forces shall meet  standards  of  competence  and
professionalism as is common in the pharmaceutical  industry.  NeoRx and Janssen
shall  compensate   their  sales  force  consistent  with  industry   standards,
including, but not limited to, incentivizing their sales representatives. In all
events,  the joint promotion and detailing shall be conducted in accordance with
the then current U.S.  Marketing  Plan.  Janssen  shall provide to NeoRx's sales
personnel, at Janssen's expense, such product training and promotional materials
(including  samples) that are reasonably  necessary to  effectively  promote the
particular product consistent with the U.S. Marketing Plan and that are provided
to the Janssen sales force.

6.6      Costs Associated With Co-Promotion

         Except to the extent specifically described in this Paragraph 6.6, each
Party  shall be  solely  responsible  for all  expenses  (direct  and  indirect)
associated  with its  Co-Promotion  activities,  including,  but not limited to,
compensation for its sales force.  Notwithstanding the foregoing,  NeoRx's sales
representatives  shall  receive  sufficient  advanced  notice of and may  attend
Janssen-organized   and-supported   scientific  and  educational  symposiums  or
meetings,  including,  but  not  limited  to,  sales  meetings,  sales  training

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<PAGE>

sessions,   symposiums,   conventions,   displays,  clinical  presentations  and
seminars,  and speaker  presentations to the extent such involve a Pre-Targeting
Product.  While NeoRx shall remain responsible for the compensation of its sales
representatives  attending  any such  educational  or  scientific  symposium  or
meeting;  Janssen  shall  compensate  NeoRx  for all  reasonable  and  necessary
out-of-pocket  expenses  incurred by such sale  representatives  attending  such
symposium  or  meeting,  provided,  however,  that the travel and room and board
expenses of NeoRx sales representatives are pre-approved by Janssen.

6.7      Co-Promotion Compliance

         Within thirty (30) days after the end of each calendar  quarter  during
the term of  Co-Promotion,  the Parties  shall submit to each other a reasonably
detailed  description  of their  promotional,  detailing and  marketing  efforts
pursuant to this Agreement.  Such description shall be based on its then current
call reporting system and shall contain a full disclosure of any changes to such
system from that previously disclosed to the other and of any noncompliance with
its promotional, detailing and marketing obligations under this Agreement.

6.8      Co-Promotion Audit of Performance

         Each Party  shall have the right to review and audit the other  Party's
call reporting records during regular business hours to confirm  satisfaction of
the  obligations  set out in this  Article VI where for any two (2)  consecutive
quarters  there is a substantial  difference  between the Party's call reporting
records  and the  records of the IMS  auditing  service or other  pharmaceutical
industry  call  reporting  service  utilized  by the Party  hereunder.  For this
purpose, each Party shall, at its expense, subscribe to the IMS auditing service
or other  pharmaceutical  industry-recognized  auditing  service  recommended by
Janssen.  Further,  each Party shall  provide to the other  Party its  reporting
records on a quarterly basis.  If, after such review,  the Parties are unable to
agree as to the results of the audit, a Party may demand a  verification  of any
certification  by  audit  of the  other  Party's  call  reporting  system  to be
conducted by a mutually agreed upon auditor.

6.9      Co-Promotion Termination for Cause

         In order to monitor the  performance  of NeoRx's sale  representatives,
the Parties shall  compare the number of  prescriptions  for each  Pre-Targeting
Product per doctor for those doctors in the target audience called on by NeoRx's
sales   representatives   ("NeoRx   Prescriptions")   against   the   number  of
prescriptions for each Pre-Targeting Product per doctor for the aggregate of the


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<PAGE>

doctors  called  on by both  NeoRx and  Janssen  sales  representatives  ("Total
Prescriptions").  Such  comparison  shall be done on a monthly  basis using data
obtained from the IMS Exponent  Database based on prescriptions  written per zip
code and the number of target  physicians in that zip code. The IMS data will be
obtained by Janssen on a monthly basis and shared with NeoRx so that Janssen and
NeoRx can  monitor the  performance  of NeoRx's  sales  force  against the Total
Prescriptions.  On an annual basis (calendar year) NeoRx's  performance  will be
evaluated and actions taken as follows:

         NeoRx Rxs Per Doctor/
         Total Rxs Per Doctor %            Consequence

         [   *   ]                         Acceptable performance.

         [   *   ]                         Performance sub par--NeoRx
         .........                         has [   *   ] to improve
         .........                         performance to acceptable level.  If
         .........                         NeoRx fails, Janssen has the right to
         .........                         terminate upon [   *   ]
         .........                         notice.

[  *  ] Confidential Treatment Requested


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<PAGE>





         NeoRx Rxs Per Doctor/
         Total Rxs Per Doctor %            Consequence

         [   *   ]                         Janssen has the right to terminate
         .........                         upon [   *   ] notice given
         .........                         within [   *   ] after the end
         .........                         of the calendar year.

         More  specifically,  if NeoRx falls  within the [ * ] range  during any
calendar year it shall have the next year to improve its  performance  to [ * ].
If during that next calendar year NeoRx fails to so improve,  Janssen shall have
the right to terminate NeoRx's right to Co-Promote that  Pre-Targeting  Product.
In  order  to avoid  the  possibility  of  NeoRx  falling  into an  unacceptable
performance  category of [ * ], Janssen shall report the comparative  numbers to
NeoRx on a monthly  basis to the extent the numbers are  available  from IMS. In
addition,  upon written  request from NeoRx,  Janssen will make  suggestions  to
NeoRx on how to improve its performance.

         Except for the remedies  provided by  Paragraph  6.14,  Janssen's  sole
remedy for any material  nonperformance  of NeoRx under this Article VI shall be
termination of NeoRx's right to Co-Promote the Pre-Targeting Product.

6.10     Co-Promotion Is Through Independent Organizations

         In implementing the obligations of Co-Promotion  hereunder,  each Party
shall have sole  discretion  as to the manner  (which shall not be  inconsistent
with the U.S.  Marketing  Plan) in which it promotes and Details  (including any
expenditure of funds in connection therewith) the Pre-Targeting Product.  Except
as otherwise  expressly provided in this Article VI, each Party shall contribute
facilities, supplies, personnel (including management and sales representatives)
and other resources to the other as each Party,  in its absolute  discretion not
inconsistent  with the express terms of this Agreement,  believes  necessary for
the proper performance of the terms of this Agreement, and each Party shall bear
its own costs, except as payment is provided to NeoRx in Paragraph 6.6, incurred
in the performance of any obligations hereunder.

6.11     Co-Promotion Does Not Affect Certain Responsibilities

         Except as expressly otherwise provided in this Agreement, Janssen shall
have the sole  right  and  responsibility,  and  shall  bear all  costs  related

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<PAGE>

thereto, to take such actions with respect to each Pre-Targeting Product that is
Co-Promoted  hereunder as would  normally be taken in  accordance  with accepted
business  practices and legal  requirements  to  manufacture  or arrange for the
manufacture  of  each   Pre-Targeting   Product  and  obtain  and  maintain  the
authorization  and/or  ability to market and  commercialize  each  Pre-Targeting
Product in the United States, including, without limitation, the following:

         (a)......Any activity relating to the manufacture of each Pre-Targeting
Product, including, without limitation, determination of the content of labeling
and the style, design and type of packaging;

         (b)......Responding to medical complaints and inquiries relating to 
each Pre-Targeting Product;

         (c)......Handling all returns of each Pre-Targeting Product; and

         (d)......Communicating  and dealing with any governmental  agencies and
satisfying  their  requirements  regarding the  authorization  and/or  continued
authorization  to market each  Pre-Targeting  Product in commercial  quantities;
provided,  however,  that NeoRx shall be able to communicate  with such agencies
regarding each Pre-Targeting Product if (i) in the reasonable opinion of NeoRx's
counsel,  such communication is necessary to comply with the requirements of any
applicable law, order or  governmental  regulation and (ii) NeoRx, if practical,
made a request of such agency to  communicate  with  Janssen  instead,  and such
agency  refused such request;  but in any such event,  unless in the  reasonable
opinion  of  NeoRx's  counsel  there is a legal  prohibition  against  doing so,
Janssen shall be  immediately  notified of such agency's  request and/or NeoRx's
intention to make such communication and Janssen shall be permitted to accompany
NeoRx to any meeting with such agency,  take part in any such  communication and
receive copies of all such communications.

6.12     NeoRx Right to Terminate

         NeoRx  shall  have the  right to  terminate  its  Co-Promotion  of each
Pre-Targeting Product hereunder,  and its obligations under this Article VI with
respect to each such Pre-Targeting Product, upon six (6) months' prior notice to
Janssen.

6.13     Trademarks

         The Joint  Marketing and Sales Committee shall select new trademarks or
the  "Avicidin(R)"  mark under which the Parties will market each  Pre-Targeting


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<PAGE>

Product,  and no right or license is granted to NeoRx  hereunder with respect to
such trademarks. All such trademarks shall be solely owned by Janssen.

6.14     Indemnification for Products

         With respect to Pre-Targeting Products covered by this Agreement:

         (a)......Janssen  shall  save,  defend and hold  NeoRx and its  agents,
directors  and employees  harmless  from and against any and all suits,  claims,
actions,  demands,  liabilities,  expenses and/or losses,  including  reasonable
legal  expense and  attorneys'  fees,  related to Third Party claims  ("Losses")
resulting directly from the manufacture,  use, handling,  storage, sale or other
disposition  of  chemical  agents or  Pre-Targeting  Products  by  Janssen,  its
Affiliates,  agents or  sublicensees,  except to the extent such  Losses  result
directly from the negligence of NeoRx.

         (b)......In  the event  that  NeoRx is  seeking  indemnification  under
Paragraph  6.14(a),  it shall  inform  Janssen of a claim as soon as  reasonably
practicable  after it  receives  notice of the claim,  shall  permit  Janssen to
assume direction and control of the defense of the claim (including the right to
settle the claim  solely for  monetary  consideration)  and shall  cooperate  as
requested (at the expense of Janssen) in the defense of the claim.

         (c)......NeoRx  shall  save,  defend and hold  Janssen  and its agents,
directors and employees  harmless from and against any and all Losses  resulting
directly from the manufacture, use, handling, storage, sale or other disposition
of chemical agents or Pre-Targeting Products by NeoRx, its Affiliates, agents or
sublicensees,  except  to the  extent  such  Losses  result  directly  from  the
negligence of Janssen.

         (d)......In  the event that  Janssen is seeking  indemnification  under
Paragraph  6.14(c),  it shall  inform  NeoRx  of a claim  as soon as  reasonably
practicable after it receives notice of the claim,  shall permit NeoRx to assume
direction and control of the defense of the claim (including the right to settle
the claim solely for monetary  consideration),  and shall cooperate as requested
(at the expense of NeoRx) in the defense of the claim.

6.15     Marketing Liaison

         NeoRx shall  appoint a  "Marketing  Liaison"  who will take part in all
Pre-Targeting   Product   marketing   discussions   and  receive  all   relevant
correspondence, memos and reports. The Marketing Liaison will be responsible for
coordinating  NeoRx  marketing  and sales  efforts with those of Janssen for the


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<PAGE>

Pre-Targeting  Products. The Marketing Liaison will have the right to review all
details of the U.S.  Marketing Plans for  Pre-Targeting  Products and shall have
the opportunity to submit to Janssen written and oral comments on such plans. In
order to perform his/her work effectively,  the Marketing Liaison is expected to
spend a  reasonable  amount of his/her  working time at the premises of Janssen.
Janssen will make available to the Marketing  Liaison an office and  secretarial
services at the relevant  site and will provide  reasonable  access to Janssen's
marketing personnel assigned to work on the Pre-Targeting Product.

6.16     Dispute Resolution

         Should  the  Joint  Marketing  and  Sales  Committee  disagree  on  any
substantive   issue  relating  to  designating   the  target   audiences  for  a
Pre-Targeting Product (a "Dispute"),  the following procedures shall be employed
to resolve such Dispute:

         (a)......Within three (3) business days of determining the existence of
a Dispute,  each Party shall prepare a written memo  summarizing the Dispute and
stating the Party's position and reasons therefor.

         (b)......Copies of each party's memos shall be forwarded to the respec-
tive heads of Janssen U.S. and NeoRx.

         (c)......A  meeting shall be convened within five (5) business' days of
the receipt of the memos or as soon thereafter as mutually agreed.

         (d)......The  heads of Janssen  and NeoRx  shall meet and  discuss  the
issues  relating  to the  Dispute  and use  reasonable  efforts to  resolve  the
Dispute.  The  standard  of  negotiation  shall  be one of good  faith  and fair
dealing.

         (e)......If  the heads of Janssen and NeoRx cannot resolve the dispute,
Janssen's  head  shall  have the  right to make the final  determination  of the
Dispute.

6.17     Transferability of Co-Promotion Right

         Upon a Change in Control  (hereinafter  defined)  involving  NeoRx, the
rights  and  duties  set  forth  in  this  Article  VI are  transferable  and/or
assignable under the following conditions:


                                       40
<PAGE>


         (a)......NeoRx shall not require the consent of Janssen where the
acquiring party has annual U.S. prescription sales of [   *   ]; or

         (b)......If the acquiring party has annual U.S.  prescription sales [ *
],  then  Janssen  shall  have  the  right to  consent  to the  transfer  and/or
assignment of the subject  rights.  Once Janssen grants such consent in writing,
it cannot be revoked.  If Janssen does not consent,  the transfer of such rights
to the acquiring party shall not take place upon a Change in Control, but rather
the acquiring party shall not have any Co-Promotion rights.

         As used herein,  a "Change in Control" means any  transaction or series
of  related  transactions  in  which a  Third  Party  acquires  or  becomes  the
beneficial owner of (i) [ * ] of the outstanding  voting  securities of NeoRx or
the surviving entity, whether by merger, consolidation,  reorganization,  tender
offer or other similar means, or (ii) all or substantially  all of the assets of
NeoRx.

                                VII. MANUFACTURE

7.1      Janssen's Responsibility

         Janssen  shall  be  solely   responsible  for  making  or  having  made
Pre-Targeting Products to be sold by Janssen or Co-Promoted by Janssen and NeoRx
under this Agreement.

7.2      Janssen's Obligation

         If Janssen  terminates this Agreement pursuant to Paragraph 13.4 [ * ],
Janssen shall  provide,  or make  arrangements  for its supplier to provide,  to
NeoRx  its  requirements  for the next [ * ] of  Avicidin.  The  price  for such
material  shall be  Janssen's  Cost of Goods Sold [ * ] for the [ * ], [ * ] for
the [ * ] and [ * ] for the [ * ] or the  supplier's  charges under its contract
with Janssen, without markup by Janssen.

[  *  ] Confidential Treatment Requested


                                       41
<PAGE>


                                  VIII. PATENTS

8.1      Maintenance of NeoRx Patents

         Except as provided in Paragraph  8.5 for patents  jointly  owned by the
Parties,  NeoRx shall  continue,  at its sole  expense,  to prosecute all patent
applications  for NeoRx  Patents  listed in Exhibit B and to file and  prosecute
NeoRx Patents covering commercially relevant,  patentable inventions relating to
NeoRx Pre-Targeting  Technology in at least the countries of Canada,  Japan, the
EPO  and  the  United  States  and,  with  reimbursement  from  Janssen  for all
reasonable  costs,  to file,  prosecute and maintain  NeoRx Patents in all other
countries requested by Janssen. Notwithstanding the foregoing, Janssen shall pay
all taxes,  maintenance fees and annuities on all NeoRx Patents. If so requested
by  Janssen,  NeoRx shall  promptly  provide  Janssen  with copies of all patent
applications  listed in  Exhibit  B, all  future  filed  NeoRx  Patents  and all
correspondence  with the patent offices in any countries  relating thereto on an
on-going basis.

8.2      Failure by NeoRx to Prosecute and/or Maintain

         If NeoRx  chooses not to prosecute  and/or  maintain any NeoRx  Patents
under  Paragraph  8.1, NeoRx shall  promptly and timely so notify  Janssen,  and
Janssen  shall,   in  its  sole   discretion,   decide  whether  to  assume  the
responsibility and expenses therefor on a country-by-country basis for each such
NeoRx Patent.  In the event Janssen decides to assume such  responsibility:  (a)
the NeoRx Patent shall be assigned to Janssen (subject to the rights  previously
granted therein to Third Parties for other than Pre-Targeting Products); (b) all
royalty  obligations with respect to the NeoRx Patent under this Agreement shall
cease;  and (c)  NeoRx  shall  have a  fully  paid-up,  royalty-free,  worldwide
nonexclusive  license to the NeoRx  Patent,  with the right to  sublicense,  for
other than Pre-Targeting Products.

8.3      Ownership of Patents

         Title to all patents claiming  inventions made solely by an employee of
a Party in the course of  performing  Development  shall be owned by such Party.
Title to all other  patents  claiming  inventions  made  jointly by employees of
Janssen and NeoRx shall be jointly  owned by Janssen and NeoRx.  The laws of the
United States with respect to joint  ownership of inventions  shall apply in all
jurisdictions;  accordingly,  except as  expressly  provided in this  Agreement,
neither Party shall have any obligation to account to the other for profits,  or
to obtain any approval of the other party to license or exploit a jointly  owned
patent, by reason of joint ownership thereof.


                                       42
<PAGE>


8.4      Disclosure of Patentable Inventions

         Each  Party  shall  provide  to  the  other  any  invention  disclosure
submitted to it in the normal  course and  disclosing  a  patentable  invention,
which is at a stage  reasonably  suitable to begin the  preparation  of a patent
application  thereto,  arising in the course of the Development.  Such invention
disclosures shall be provided to the other Party promptly after submission,  or,
in the case where no invention  disclosure is made, any patent application shall
be provided promptly after it is initially drafted.

8.5      Jointly Owned Patent Filings

         The filing and  prosecution  of jointly  owned patents shall be only as
mutually agreed by Janssen and NeoRx. In such  connection,  the Parties agree to
cooperate in good faith to obtain broad patent protection.

         Janssen  shall be  responsible  at the expense of Janssen for drafting,
filing,  prosecuting,  maintaining  and  defending  any  jointly  owned  patents
relating  primarily  to the  Pre-Targeting  Product.  Janssen  shall  keep NeoRx
apprised of the status of each such jointly owned patent. If, during the term of
this  Agreement,  Janssen  intends to allow any jointly owned patent to lapse or
become abandoned without having first filed a substitute, Janssen shall promptly
notify  NeoRx of such  intention,  and, if  practical,  at least sixty (60) days
prior to the date upon which such patent  shall lapse or become  abandoned,  and
NeoRx  shall  thereupon  have  the  right,  but not the  obligation,  to  assume
responsibility for the prosecution,  maintenance and defense thereof in its sole
name and at its own expense. In the event NeoRx assumes such responsibility, the
patent or patent  application  shall be assigned to NeoRx and excluded  from the
definition of NeoRx Patents.

                                       43
<PAGE>


8.6      Parties' Cooperation in Obtaining Patent Extensions

         The Parties  shall  cooperate in order to avoid loss of any rights that
may otherwise be available to the Parties under the U.S. Drug Price  Competition
and Patent  Term  Restoration  Act of 1984,  the  Supplementary  Certificate  of
Protection of the Member States of the European Union and other similar measures
in any other country. Without limiting the foregoing, Janssen shall notify NeoRx
promptly  upon  receipt  of a BLA  approval  to  market  licensed  Pre-Targeting
Products  in the  United  States and timely  supply  NeoRx with all  information
necessary to file an application  for patent term  extension in connection  with
any  relevant  NeoRx  Patent  within  the sixty (60) day  period  following  BLA
approval.  The same  cooperation  and  obligations  shall apply with  respect to
patent term extensions in any other country.

                                IX. INFRINGEMENT

9.1      Infringement of Third Party Patents

         If,  as a result  of the  manufacture,  use or sale of a  Pre-Targeting
Product  in any  country,  Janssen  and/or  its  Affiliate  is sued  for  patent
infringement  or threatened with such a lawsuit or other action by a Third Party
(other  than with  respect  to Third  Party  Patents),  Janssen  shall be solely
responsible for defending against any such assertions at its cost and expense.

9.2      Infringement by Third Parties of NeoRx Patents

         Except as provided in Paragraph  9.3 for patents  jointly  owned by the
Parties,  in the event  that  there is an  infringement  of a NeoRx  Patent on a
commercial scale by a Third Party involving a Pre-Targeting Product,  Janssen or
its Affiliates shall notify NeoRx in writing to that effect, including with said
written notice evidence establishing a case of infringement by such Third Party.
NeoRx shall have the first right to bring an infringement suit against the Third
Party and shall bear all the expenses of any suit brought by it.  Janssen and/or
its  Affiliates  will  cooperate  with NeoRx in any such suit and shall have the
right to consult  with NeoRx and be  represented  by its own  counsel at its own
expense. If, after the expiration of one hundred twenty (120) days from the date
of receipt of notice of  infringement  from Janssen or its Affiliate,  NeoRx has
not  overcome  the  case of  infringement,  obtained  a  discontinuance  of such
infringement  or brought  suit against the Third Party  infringer,  then Janssen
shall have the right, in its sole discretion,  but not the obligation,  to bring
such  suit at its own  expense  and in its  own  name,  if  possible,  for  such
infringement.  If  necessary,  NeoRx  will  permit the suit to be brought in its
name.  Janssen shall bear all the expenses of any suit brought by it. NeoRx will


                                       44
<PAGE>

cooperate with Janssen in any such suit and shall have the right to consult with
Janssen and be  represented  by its own counsel at its own  expense.  All monies
recovered  by  either  Party  from  a  final   judgment  or  settlement  of  any
infringement  suit  shall,  after  reimbursement  of the  expenses  of the Party
bringing such suit, be shared as follows: [ * ] to Janssen and [ * ] to NeoRx.

9.3      Infringement by Third Parties of Jointly Owned Patents

         In the  event  there is  infringement  of a jointly  owned  patent on a
commercial scale by a Third Party in the Field,  Janssen or its Affiliates shall
notify NeoRx of such  infringement  and shall have the first right,  but not the
obligation,  to bring an  infringement  suit  against  such Third  Party.  If an
infringement  suit is not brought  within one hundred  twenty (120) days,  NeoRx
shall  have the right,  but not the  obligation,  to bring such an  infringement
suit.  The Parties  will  cooperate in any such suit and shall have the right to
consult  with the other party and be  represented  by its own counsel at its own
expense. If necessary, the other party will permit the suit to be brought in its
name. All monies  recovered by a Party in a final judgment or settlement of such
infringement  suit  shall,  after  reimbursement  of the  expenses of Janssen in
bringing such suit, be shared as follows:  [ * ] to the Party  bringing the suit
and [ * ] to the other Party.

                        X. TRADEMARKS AND CORPORATE NAME

         All  trademarks  (except  the  "NeoRx"  mark) to be utilized by Janssen
and/or its Affiliates on  Pre-Targeting  Products under this Agreement  shall be
owned by Janssen  and/or its  Affiliates.  Except to the  extent  prohibited  by
applicable  law,  Pre-Targeting  Products  covered by this Agreement  shall bear
NeoRx's corporate name in a reasonable location on outer packaging labels and on
any package inserts.  Janssen shall mention, in certain appropriate forms of its
advertising and promotional literature,  NeoRx's contribution to the development
of each  Pre-Targeting  Product to the extent  permitted by applicable  law. The
first use of any such reference shall require NeoRx's approval,  which shall not
be unreasonably withheld.

[  *  ] Confidential Treatment Requested


                                       45
<PAGE>


                               XI. CONFIDENTIALITY

11.1     Confidentiality; Exceptions

         Except  to  the  extent  expressly  authorized  by  this  Agreement  or
otherwise  agreed in  writing,  the  Parties  agree  that,  for the term of this
Agreement  and for five (5) years  thereafter,  the  receiving  Party shall keep
confidential and shall not publish or otherwise  disclose or use for any purpose
other  than as  provided  for in  this  Agreement  any  Information,  and  other
confidential and proprietary  information and materials,  disclosed or otherwise
furnished  to it by the other Party  pursuant to this  Agreement  (collectively,
"Confidential Information"),  except to the extent that it can be established by
the receiving Party that such Confidential Information:

         (a)......was  in  the  lawful  knowledge  and  possession  of,  or  was
independently  developed  by,  the  receiving  Party  prior  to the  time it was
disclosed to, or learned by, the receiving Party as evidenced by written records
kept in the ordinary course of business or other documentary proof of actual use
by the receiving Party;

         (b)......was generally available to the public or otherwise part of the
public domain at the time of its disclosure to the receiving Party;

         (c)......became  generally available to the public or otherwise part of
the  public  domain  after its  disclosure  and other  than  through  any act or
omission of the receiving Party in breach of this Agreement; or

         (d)......was  disclosed  to the  receiving  Party,  other than under an
obligation of  confidentiality,  by a Third Party who had no  obligation  not to
disclose such Confidential Information to others.

11.2     Authorized Disclosure

         Each Party may disclose Confidential  Information of the other Party as
follows:  (a) to Third Parties under appropriate terms and conditions  including
confidentiality  provisions  substantially equivalent to those in this Agreement
for  consulting,  manufacturing,  development,  external  testing and  marketing
trials with  respect to the  products  covered by this  Agreement  or (b) to the
extent such disclosure is reasonably  necessary in filing or prosecuting patent,
copyright  and  trademark  applications,  prosecuting  or defending  litigation,
complying  with  applicable  governmental   regulations,   obtaining  Regulatory
Approvals,  conducting  preclinical or clinical trials,  or marketing  products;
provided,  however, that if a Party is required by law or regulation to make any
such disclosure of the other Party's  Confidential  Information it will,  except


                                       46
<PAGE>

where  impracticable  for necessary  disclosures  (for example,  in the event of
medical  emergency),  give reasonable  advance notice to the other Party of such
disclosure  requirement and will, except to the extent inappropriate in the case
of patent  applications,  use its  reasonable  efforts  to  secure  confidential
treatment of such Confidential Information required to be disclosed.  Nothing in
this  Article  XI shall  restrict  any  Party  from  using for any  purpose  any
Information developed by it during the course of this Agreement.

11.3      Survival

         This Article XI shall  survive the  termination  or  expiration of this
Agreement for a period of five (5) years.

                XII. REPRESENTATIONS AND WARRANTIES; PERFORMANCE

12.1     Representations and Warranties

         Each Party hereby represents and warrants and covenants as follows:

         (a)......This  Agreement is a legal and valid  obligation  binding upon
such Party and enforceable in accordance with its terms. The execution, delivery
and  performance  of this  Agreement  by such  Party  do not  conflict  with any
agreement, instrument or understanding,  oral or written, to which it is a Party
or by  which  it is  bound,  or  violate  any law or  regulation  of any  court,
governmental body or administrative or other agency having jurisdiction over it.

         (b)......Each  party  has not  granted,  and  during  the  term of this
Agreement  will  not  grant,  any  right  to any  Third  Party  relating  to its
respective  technology in the Field  (excluding the Crossover Field with respect
to NeoRx)  that  would  conflict  with the  rights  granted  to the other  Party
hereunder,  except,  in the case of NeoRx, the rights granted under the contract
described in Paragraph 1.27(b).

         (c)......Each Party owns or Controls its respective know-how.

12.2     Disclaimer

         EXCEPT  AS  SET  FORTH  IN  THIS   AGREEMENT,   NEORX  MAKES  NO  OTHER
REPRESENTATIONS   OR  WARRANTIES   WITH  RESPECT  TO  THE  NEORX   PRE-TARGETING
TECHNOLOGY,  NEORX  PATENTS AND NEORX  KNOW-HOW,  EXPRESS OR IMPLIED,  INCLUDING
WARRANTIES, MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE, PATENTABILITY AND
NONINFRINGEMENT.


                                       47
<PAGE>


12.3     Performance by Affiliates

         The  Parties  recognize  that  each  may  perform  some  or  all of its
obligations under this Agreement through  Affiliates;  provided,  however,  that
each Party shall remain  responsible  and be guarantor of the performance by its
Affiliates  and shall cause its Affiliates to comply with the provisions of this
Agreement in connection with such performance.

                           XIII. TERM AND TERMINATION

13.1     Term

         This  Agreement  shall  commence as of the Effective  Date and,  unless
sooner terminated as provided herein, shall continue in effect until the date on
which  NeoRx is no longer  entitled  to receive a royalty  on any  Pre-Targeting
Product under this Agreement.  After expiration (but not  termination),  Janssen
and its  Affiliates  shall have a fully  paid-up  (except for  payments to Third
Parties), irrevocable, nonexclusive license to sell, have sold, distribute, use,
make and have made Pre-Targeting Products licensed hereunder.

13.2     Termination for Breach

         In the event that (a) either  Party shall  commit a material  breach at
any time and (b) such defaulting Party shall fail to remedy such material breach
within  sixty  (60) days after the date of notice  thereof by the  nondefaulting
Party to the  defaulting  Party (or, if such material  breach cannot be remedied
within  sixty  (60)  days,  such  longer  period  of time  as may be  reasonably
necessary; provided, however, that the defaulting Party commences to remedy such
material  breach  within  such sixty (60) day  period  and  thereafter  proceeds
promptly and diligently to complete such remedy),  then the nondefaulting  Party
may at any time thereafter terminate this Agreement.

13.3     Termination for Bankruptcy

         Either Party hereto  shall have the right to terminate  this  Agreement
forthwith  by  written  notice  to the other  Party  (a) if the  other  Party is
declared  insolvent or bankrupt by a court of competent  jurisdiction,  (b) if a
voluntary  or  involuntary  petition  in  bankruptcy  is filed  in any  court of
competent  jurisdiction  against  the  other  Party  and such  petition  remains
undismissed, undischarged or unbonded for a period of ninety (90) days after the
filing  thereof,  or (c) if the other Party shall make or execute an  assignment
for the benefit of creditors generally.


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<PAGE>


13.4     Janssen's Termination Without Cause

         Janssen  may not  terminate  this  Agreement,  other than  pursuant  to
Paragraph  13.2 or 13.3,  during the period  beginning on the Effective Date and
ending twelve (12) months thereafter, except in the following situations:

         (a)......There is a Change in Control as described in Paragraph 6.17 or

         (b)......A patent of a Third Party (other than a Third Party Patent) is
uncovered  containing a Valid Claim that would be infringed if the Pre-Targeting
Product in Development is sold.

         Notice of termination  under either clause (a) or (b) shall be given at
least one (1) month in advance.  At any time after the twelve (12) month period,
however,  Janssen  may  terminate  this  Agreement  upon ninety (90) days' prior
notice for any reason.

13.5     Rights and Obligations Upon Termination Under Paragraph 13.2 or 13.3 by
         NeoRx or Under Paragraph 13.4 by Janssen

         In the event  this  Agreement  is  terminated  by Janssen  pursuant  to
Paragraph 13.4 or by NeoRx pursuant to Paragraph 13.2 or 13.3, Janssen agrees:

         (a)......To return to NeoRx any NeoRx Know-How in its possession;

         (b)......Not to use the NeoRx Know-How as long as it has to be kept
confidential pursuant to Article XI;

         (c)......That its licenses and rights under the NeoRx Patents are
terminated;

         (d)......To   transfer,   at  NeoRx's  written  request,   all  Janssen
Information  useful  for or related to  Pre-Targeting  Products  that were being
Developed hereunder and all Drug Approval  Applications and Regulatory Approvals
for use by NeoRx or its designee; and

         (e)......To   the  extent   requested  by  NeoRx,   transfer  to  NeoRx
responsibility for ongoing  Development,  including contracts with Third Parties
for such work with costs for such on-going (but not past) Development assumed by
NeoRx as of the effective date of termination.


                                       49
<PAGE>


13.6     Survival

         Any accrued obligations and the provisions of Articles XIV, XV and XVII
and Paragraphs 3.6 (with respect to NeoRx's sublicense and right to take over as
a direct license in the last sentence),  4.15, 4.16, 6.14, 7.2, 8.2(c), 13.5 and
21.9 shall survive expiration or termination of this Agreement.

13.7     Accrued Rights, Surviving Obligations

         Termination,  relinquishment  or expiration  of this  Agreement for any
reason  shall be without  prejudice to any rights that shall have accrued to the
benefit of either Party prior to such termination, relinquishment or expiration,
including,  but not limited to, the payment obligations under Paragraphs 4.1-4.4
and 4.6 and any and all damages arising from any breach hereunder.

13.8     Termination Not Sole Remedy

         Termination is not the sole remedy under this Agreement and, whether or
not termination is effected,  all other remedies will remain available except as
agreed to otherwise herein.

                              XIV. INDEMNIFICATION

14.1     Research and Development Indemnification

         Each Party (the "Indemnifying Party") shall indemnify,  defend and hold
the other Party (the "Indemnified  Party") harmless from and against any and all
liabilities,  claims, damages, costs, expenses or money judgments incurred by or
rendered  against the  Indemnified  Party and its  Affiliates  and  sublicensees
incurred  in  the  defense  or  settlement  of a  Third  Party  lawsuit  or in a
satisfaction  of a Third Party  judgment  arising out of any injuries to persons
and/or damage to property  resulting  from  negligent  acts of the  Indemnifying
Party performed in carrying out the  development  program  hereunder,  including
failure by the  Indemnifying  Party to provide  the  Indemnified  Party with any
Information  of the  Indemnifying  Party that,  if timely  received,  would have
avoided injury, death or damage; provided, however, that such failure to provide
such Information is due to negligence on the part of the Indemnifying Party.

14.2     Janssen Indemnification

         In  addition  to its  obligations  in  Paragraph  14.1,  Janssen  shall
indemnify  and hold NeoRx  harmless  from and against  any and all  liabilities,


                                       50
<PAGE>

claims,  damages,  costs,  expenses  or money  judgments  that  result  from the
Development,  manufacture,  promotion,  sale or use of any and all Pre-Targeting
Products under this Agreement.

14.3     Notification

         The Indemnified  Party shall promptly notify the Indemnifying  Party in
writing  of  any  such  liability,  claim,  damage,  costs,  expenses  or  money
judgments,  and the Indemnifying  Party, upon written request by the Indemnified
Party, shall promptly defend or settle such at the Indemnifying Party's expense.

                             XV. DISPUTE RESOLUTION

15.1     Alternative Dispute Resolution

         Any  dispute,  controversy  or claim  arising out of or relating to the
validity,  construction,   enforceability  or  performance  of  this  Agreement,
including  disputes  relating to the alleged  breach or to  termination  of this
Agreement, shall be settled by binding Alternative Dispute Resolution ("ADR") in
the manner described below:

         (a)......If a Party intends to begin an ADR to resolve a dispute,  such
Party  shall  provide  written  notice  (the "ADR  Request")  to the other Party
informing such other Party of such intention and the issues to be resolved.

         (b)......Within  fourteen  (14)  days  after  the  receipt  of the  ADR
Request, the other Party may, by written notice to the Party initiating ADR, add
additional issues to be resolved.

15.2     Arbitration Procedure

         The ADR shall be conducted  pursuant to the  International  Arbitration
Rules of the American  Arbitration  Association then in effect.  Notwithstanding
those rules, the following provisions shall apply to the ADR hereunder.

         (a)      Arbitrator

         The ADR shall be  conducted  by a panel of three (3)  arbitrators  (the
"Panel").  Each Party  shall have the right to appoint  one member of the Panel,
with the third  member to be mutually  agreed upon by the two (2) Panel  members
appointed  by the  Parties  or  appointed  in  accordance  with the rules of the
American Arbitration  Association.  All Panel members shall be selected from the
CPR  Panel of  Distinguished  Neutrals  of the CPR  Institute  of  Distinguished
Neutrals.  Each Party  shall make its  appointment  within  twenty  (20) days of
receipt of the ADR Request and the Third Panel  member  shall be selected by the
two (2) Panel members within ten (10) days of the selection of the first two (2)
Panel members.

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<PAGE>


         (b)      Proceedings

         The Parties will cooperate in good faith in the  voluntary,  prompt and
informal  exchange of documents and other  information  relevant to the ADR. The
Parties  and the  Panel  will make  every  effort to  conclude  the  information
exchange  process  within  ninety (90) days after the Panel is selected.  Within
seven (7) days after  selection of the Panel,  each Party may serve on any other
Party up to ten (10)  interrogatories,  without  subparts,  for the  purpose  of
identifying  documents and  witnesses.  These  interrogatories  will be answered
within seven (7) days.

         At any time after the selection of the Panel,  but no later than thirty
(30)  days  before  the  ADR  hearing,  each  Party  may  take up to  three  (3)
depositions of an opposing Party as a matter of right.  The Parties will attempt
to agree to time,  location and duration of the deposition,  and, if the Parties
do not agree, these will be determined by the Panel.

         Any Party may  conduct  depositions  of its own  witnesses  that may be
introduced  as  evidence  at the ADR  hearing if the other  Party was given fair
opportunity to attend the deposition and cross-examine.  Upon the request of any
Party,  the Panel will  conduct a  conference  for the  purpose  of  determining
additional   information  to  be  exchanged.   Parties  may  request  additional
depositions,  interrogatories  or document  production.  If the Panel determines
that the requesting  Party has a reasonable  need for the requested  information
and that the request is not overly  burdensome on the opposing Party,  the Panel
may order the additional information exchange.

         As they become aware of new documents or information, including experts
who may be  called  upon to  testify,  all  Parties  remain  under a  continuing
obligation  to provide  documents  upon which they  rely,  to  supplement  their
responses  and to honor any informal  agreements or  understandings  between the
Parties regarding documents or information to be exchanged.  Documents that have
not  been  previously  exchanged  will  not be  considered  by the  Panel at the
hearing, unless agreed by the Parties.

         The Parties will promptly  notify the Panel when an unresolved  dispute
exists regarding  discovery  issues.  The Panel will discuss the matter with the
Parties to determine  the nature of the dispute and will attempt to resolve that
dispute.  If the Panel does not resolve the  dispute,  the Panel will  arrange a
conference  concerning the dispute before the Panel by telephone,  or in person,
and the Panel will decide the dispute.

                                       52
<PAGE>


         The Panel will determine the location, date and time of the ADR hearing
and other  proceedings  after  consultation  with the Parties  and will  provide
reasonable notice of the hearing date and time. The Panel will make every effort
to  schedule  the ADR  hearing  within  one  hundred  twenty  (120)  days of the
commencement of ADR, absent unusual circumstances.

         The  Parties  may  agree on or the  Panel  for good  cause  may order a
rescheduling of the hearing date.

         The Panel will  ordinarily  conduct  the ADR  hearing in the manner set
forth herein.  The Panel may vary these procedures if the Panel determines it is
reasonable and appropriate to do so. The Panel may impose reasonable time limits
on each phase of the proceeding and may limit testimony to exclude evidence that
would be immaterial or unduly repetitive;  provided,  however,  that all Parties
are afforded the opportunity to present material and relevant evidence.

         The Panel will require  witnesses to testify under oath if requested by
any Party.

         The Panel will  determine the order of proof,  which will  generally be
similar to that of a court trial, including opening and closing statements.

         When the Panel  determines that all relevant and material  evidence and
arguments have been presented,  the Panel will declare the hearing  closed.  The
Panel may defer the  closing of the hearing for up to twenty (20) days to permit
the Parties to submit post-hearing  briefs and/or to make closing arguments,  as
the Panel deems appropriate, before rendering an award.

         The Panel will render the award  within ten (10) days after the date of
the closing of the hearing  or, if an ADR  hearing has been  waived,  within ten
(10) days after the date of the Panel's receiving all materials specified by the
parties.  The decision and award of a majority of the Panel will  constitute the
ADR award and will be binding on the Parties.

         The Panel shall,  in rendering its decision,  apply the substantive law
of the  State  of  Illinois  U.S.A.,  without  regard  to its  conflict  of laws
provisions,  except that the  interpretation  and enforcement of this Article XV
shall be governed by the Federal  Arbitration  Act.  The  proceeding  shall take
place in the City of Chicago,  Illinois,  U.S.A.,  or such other place as may be
mutually agreed upon by the Parties.  The fees of the Panel shall be paid by the


                                       53
<PAGE>

losing Party,  which shall be designated by the Panel. If the Panel is unable to
designate a losing Party,  it shall so state and the fees shall be split equally
between the Parties.

         (c)      Award

         The Panel is  empowered to award any remedy  allowed by law,  including
money damages,  prejudgment  interest and attorneys'  fees and expenses,  and to
grant final,  complete,  interim or interlocutory  relief,  including injunctive
relief. Notwithstanding the foregoing, punitive damages may not be awarded.

         (d)      Costs

         Except as set forth in Paragraph 15.2(b), each Party shall bear its own
legal fees.

         (e)      Confidentiality

         The ADR  proceeding  shall be  confidential  and the Panel  shall issue
appropriate   protective   orders  to  safeguard   each   Party's   Confidential
Information.  Except as required by law,  no Party shall make (or  instruct  the
Panel to make) any public  announcement  with respect to the ADR  proceedings or
the decision of the Panel without the prior written  consent of the other Party.
The existence of any dispute  submitted to ADR, and the award,  shall be kept in
confidence by the Parties and the Panel,  except as required in connection  with
the enforcement of such award or as otherwise required by applicable law.

15.3     Survivability

         Any duty to arbitrate  under this Agreement  shall remain in effect and
enforceable after termination of this Agreement for any reason.

15.4     Jurisdiction

         For the  purposes of this  Article XV, the  Parties  acknowledge  their
diversity (NeoRx having its principal place of business in Seattle,  Washington,
U.S.A., and Janssen  Pharmaceutica,  N.V. having its principal place of business
in  Beerse,  Belgium)  and agree to accept  the  exclusive  jurisdiction  of the
Federal District Court in Chicago,  Illinois,  U.S.A.,  and any courts of appeal
therefrom for the purposes of enforcing  awards entered pursuant to this Article
XV and for enforcing the agreements reflected in this Article XV.

                                       54
<PAGE>


                            XVI. LICENSOR BANKRUPTCY

         All rights and licenses  granted under or pursuant to this Agreement by
NeoRx to Janssen  are,  and shall  otherwise  be deemed to be, for  purposes  of
Section  365(n) of Title 11,  U.S.  Code (the  "Bankruptcy  Code"),  licenses of
rights to  "intellectual  property"  as  defined  under  Section  101(60) of the
Bankruptcy  Code.  The Parties agree that Janssen,  as a licensee of such rights
under this Agreement,  shall retain and may fully exercise all of its rights and
elections  under the  Bankruptcy  Code.  NeoRx  agrees  during  the term of this
Agreement to create and maintain  current copies or, if not amenable to copying,
detailed descriptions or other appropriate  embodiments of all such intellectual
property licensed hereunder. The Parties further agree that, in the event of the
commencement of a bankruptcy proceeding by or against NeoRx under the Bankruptcy
Code,  Janssen shall be entitled to a complete  duplicate of (or complete access
to, as appropriate) any such  intellectual  property and all embodiments of such
intellectual property, and the same, if not already in its possession,  shall be
promptly  delivered to Janssen,  upon written request  therefor by Janssen,  (a)
upon any such  commencement of a bankruptcy  proceeding,  unless NeoRx elects to
continue to perform all of its obligations  under this Agreement,  or (b) if not
delivered under clause (a) above,  upon the rejection of this Agreement by or on
behalf of NeoRx.

                                  XVII. NOTICES

         Any payment,  notice or other communication required or permitted to be
made or given to either  Party  hereto  pursuant to this  Agreement  shall be in
writing  in case of a notice  or  communication  and  shall be  deemed  given if
delivered  by hand or by facsimile  transmission  (receipt  verified),  telexed,
received by registered or certified  mail (return  receipt  requested),  postage
prepaid,  or sent by overnight or express courier service, to the Parties at the
following  addresses (or at such other address for a Party as shall be specified
by like notice; provided,  however, that notices of a change of address shall be
effective only upon receipt thereof):

         In the case of NeoRx:

                  NeoRx Corporation
                  410 West Harrison Street
                  Seattle, Washington 98119-4004, U.S.A.
                  Attention: President
                  Telephone:        (206) 281-7001
                  Telecopy:         (206) 284-7112

                                       55
<PAGE>

         With a copy to:

                  Perkins Coie
                  1201 Third Avenue, 40th Floor
                  Seattle, WA 98101-3099, U.S.A.
                  Attention:        James R. Lisbakken
                  Telephone:        (206) 583-8888
                  Telecopy:         (206) 583-8500

         In case of Janssen:

                  Janssen Pharmaceutica, N.V.
                  Turnhoutseweg 30
                  2340 Beerse, Belgium
                  Attention:        President, Janssen Research Foundation
                  Telephone:        32 14 60 2613
                  Telecopy:         32 14 60 2111

         With a copy to:

                  Office of General Counsel
                  Johnson and Johnson
                  One Johnson and Johnson Plaza
                  New Brunswick, New Jersey 08933, U.S.A.
                  Telephone:        (908) 524-2485
                  Telecopy:         (908) 524-2788

                                XVIII. PUBLICITY

18.1     Publicity

         In the absence of specific agreement between the Parties, neither Party
shall, without the prior written consent of the other Party (which consent shall
not be unreasonably withheld or delayed),  originate any publicity, news release
or  public  announcement,  written  or oral,  whether  to the  public  or press,
relating to this Agreement, including its existence, the subject matter to which
it relates, performance under it or any of its terms or to any amendment hereto,
except only such  announcement as in the opinion of counsel for the Party making
such announcement is required by law to be made. Any such announcements shall be
factual.  If a Party  decides to make an  announcement  required by law, it will
give the other Party five (5)  business  days'  advance  written  notice,  where


                                       56
<PAGE>

possible,  of the text of the  announcement so that the other Party will have an
opportunity  to comment on the  announcement.  To the extent that the  receiving
Party requests that any information in the materials proposed to be disclosed be
deleted,  the  disclosing  Party shall  request  confidential  treatment of such
information pursuant to any applicable rules or regulations  (including those of
the Securities and Exchange Commission)  relating to the confidential  treatment
of such  information  so that  there  is  omitted  from the  materials  that are
proposed to be disclosed any  information  that the receiving  Party  reasonably
requests to be deleted. The Parties shall mutually agree upon a press release to
be made on or promptly after the Effective Date.

18.2     Scientific Publications

         Except for materials submitted prior to the Effective Date by NeoRx for
publication or scientific  meetings  scheduled prior to the Effective Date, each
Party  shall  submit  any other  proposed  publication  containing  Confidential
Information  to the other  Party at least  thirty  (30) days in advance to allow
that Party to review such planned public  disclosure.  The reviewing  party will
promptly  review such proposed  publication  and make any objections that it may
have to the  publication  of the  Confidential  Information  contained  therein.
Should  the  reviewing  Party  make  an  objection  to  the  publication  of the
Confidential  Information,  then the Parties  shall discuss the  advantages  and
disadvantages of publishing such  Confidential  Information.  If the Parties are
unable to agree on  whether  to  publish  the  same,  the Vice  President,  Drug
Discovery of Janssen Research Foundation, and NeoRx's Vice President of Research
shall discuss the advantages and disadvantages of publishing such, with the Vice
President, Drug Discovery of Janssen Research Foundation having the final say.

                               XIX. FORCE MAJEURE

         Neither  Party hereto shall be liable to the other Party for any losses
or damages  attributable  to a material  breach or other default in or breach of
this Agreement that is the result of war (whether declared or undeclared),  acts
of God, revolution, strike, fire, earthquake, flood, pestilence, riot, enactment
or change of laws and regulations, accident(s), labor trouble, or shortage of or
inability to obtain  material,  equipment or transport or any other cause beyond
the  reasonable  control  of the  Party,  and  the  performance  of  obligations
hereunder shall be suspended  during,  but no longer than, the existence of such
cause.


                                       57
<PAGE>


                                 XX. INTEGRATION

         It is the mutual desire and intent of the Parties to provide  certainty
as to their future rights and remedies against each other by defining the extent
of their  mutual  undertakings  as provided  herein.  The  Parties  have in this
Agreement incorporated all representations,  warranties, covenants, commitments,
and  understandings  on which they have relied in entering into this  Agreement,
and,  except as  provided  for  herein,  neither  Party  has made any  covenant,
agreement or other commitment to them concerning its future action. Accordingly,
this  Agreement,  all  Exhibits  attached  hereto  and all  documents  delivered
concurrently  herewith or referenced  herein (a) constitute the entire agreement
and  understanding  between the Parties  with  respect to the matters  contained
herein,  and there are no  promises,  representations,  warranties,  conditions,
provisions  or  terms  related  thereto  other  than  those  set  forth  in this
Agreement,   and  (b)   supersede  all  previous   understandings,   agreements,
representations  and  warranties  by or between  the  Parties,  written or oral,
relating to the subject matter hereof.

                               XXI. MISCELLANEOUS

21.1     Amendments

         This  Agreement  will not be binding upon the Parties until it has been
signed  herein  below by or on behalf of each Party,  in which event it shall be
effective as of the Effective Date. No amendment or modification hereof shall be
valid or binding upon the Parties unless made in writing and duly executed by or
on behalf of all Parties hereto.

21.2     Laws

         All matters affecting the  interpretation,  validity and performance of
this Agreement  shall be governed by the internal laws of the State of Illinois,
U.S.A.  without  regard to its conflict of law  principles,  except as otherwise
expressly provided herein.

21.3     Severability

         Any  provision  hereof  that  is  prohibited  or  unenforceable  in any
jurisdiction  shall, as to such jurisdiction,  be ineffective only to the extent
of such  prohibition  or  unenforceability  without  invalidating  the remaining
provisions  hereof or affecting the validity or enforceability of such provision
in any other jurisdiction.

                                       58
<PAGE>


21.4     Headings

         The headings of the several  sections are inserted for  convenience  of
reference  only and are not intended to be a part of or to affect the meaning or
interpretation of this Agreement.

21.5     Waiver

         No failure or delay by any Party to insist on the strict performance of
any term, condition, covenant or agreement of this Agreement, or to exercise any
right,  power or remedy  hereunder or  consequent  upon a breach  hereof,  shall
constitute a waiver of any such term,  condition,  covenant,  agreement,  right,
power or remedy of any such breach or preclude  such Party from  exercising  any
such right, power or remedy at any later time or times.

21.6     Representations

         Each  of  the  Parties  hereto  acknowledges  and  agrees  that  (a) no
representation  or promise not  expressly  contained in this  Agreement has been
made  by  the  other  Party   hereto  or  by  any  of  its  agents,   employees,
representatives  or attorneys,  (b) this  Agreement is not being entered into on
the basis of, or in  reliance  on,  any  promise or  representation,  express or
implied, covering the subject matter hereof, other than those that are set forth
expressly in this  Agreement,  and (c) each Party has had the  opportunity to be
represented  by  counsel  of its  own  choice  in  this  matter,  including  the
negotiations that preceded the execution of this Agreement.

21.7     Compliance With Laws

         The Parties shall comply with all applicable laws,  rules,  regulations
and orders of the United  States and all  jurisdictions  and any agency or court
thereof in  connection  with this  Agreement and the  transactions  contemplated
thereby.

21.8     Relationship of Parties

         Nothing  herein  shall be  construed  to  create  any  relationship  of
employer and employee, agent and principal, partnership or joint venture between
the  Parties.  Each Party is an  independent  contractor.  Neither  Party  shall
assume, either directly or indirectly,  any liability of or for the other Party.
Neither  Party shall have the  authority to bind or obligate the other Party and
neither Party shall represent that it has such authority.

                                       59
<PAGE>


21.9     Interest

         Any past due payments under this Agreement  shall accrue and be payable
with interest at the "prime rate" of interest  quoted by The Wall Street Journal
(or if not published, another appropriate publication) for the last business day
of each  month plus [ * ] or the  maximum  rate  permitted  by  applicable  law,
whichever is less.

21.10    Counterparts

         This Agreement may be executed in  counterparts,  any one of which need
not  contain  the  signatures  of more than one Party,  but all of which,  taken
together, shall constitute one and the same agreement.

         IN WITNESS  WHEREOF,  the  Parties  have  executed  this  Agreement  in
duplicate originals by their proper officers as of the date and year first above
written.

                                    JANSSEN PHARMACEUTICA, N.V.


                                    By /s/  Staf VanReet
                                            -----------------------------------
                                    Title:  Managing Officer 
                                    
                                    Date:   August 8, 1997       

                                    By
                                            -----------------------------------
                                    Title:
                                            -----------------------------------


                                    NEORX CORPORATION


                                    By /s/  Paul G. Abrams
                                            -----------------------------------
                                    Title:  President and CEO
                                            
                                   

[  *  ] Confidential Treatment Requested

                                       60
<PAGE>


                                    


                                    EXHIBIT A

                               COST OF GOODS SOLD

         [   *   ]


 
                                       A-1

[  *  ] Confidential Treatment Requested

<PAGE>



                                    EXHIBIT B

                                  NEORX PATENTS

         [   *   ]



                                      B-1

[  *  ] Confidential Treatment Requested

<PAGE>



                                    EXHIBIT C

                              NEORX COST CATEGORIES



         [   *   ]

[  *  ] Confidential Treatment Requested

                                      C-1



                                      
<PAGE>




                                    EXHIBIT D

                         12/4/96 Letter from P. Verheyen



         [   *   ]

                                      
[  *  ] Confidential Treatment Requested

                                      D-1




                                  EXHIBIT 10.2



                                       TO



                               NeoRx Corporation's



                               Report on Form 8-K



                                      Dated



                                October 7, 1997













<PAGE>


                       PREFERRED STOCK PURCHASE AGREEMENT


         This PREFERRED STOCK PURCHASE AGREEMENT (this "Agreement"), dated as of
August 8, 1997, is entered into by and between NEORX  CORPORATION,  a Washington
corporation (the "Company"),  and JOHNSON & JOHNSON DEVELOPMENT  CORPORATION,  a
New Jersey corporation (the "Investor").

                                     RECITAL

         The  Investor  desires to purchase  from the  Company,  and the Company
desires to sell to the Investor,  shares of the  Company's  Series 4 Convertible
Preferred  Stock,  $.02 par value (the  "Preferred  Stock"),  upon the terms and
conditions  set forth herein and in connection  with the execution of a separate
License and Development Agreement between Janssen Pharmaceutica N.V. ("Janssen")
and the Company, dated as of even date herewith (the "License Agreement").

                                    AGREEMENT

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

1.       Purchase and Sale

         Upon the terms and subject to the  conditions  of this  Agreement,  the
Investor  hereby agrees to purchase from the Company for the aggregate  purchase
price of Five Million U.S. Dollars (US $5,000,000) (the "Purchase  Price"),  and
the Company hereby agrees to issue, sell and deliver to the Investor in exchange
for the Purchase  Price,  one thousand  (1,000)  shares of Preferred  Stock (the
"Shares"),  which amount has been  determined by dividing (a) the Purchase Price
by (b) $5,000 per share.

         The Investor  shall pay the Purchase  Price to the Company by bank wire
transfer to the account  designated by the Company,  such payment to be received
by the date of this  Agreement.  On the date of this Agreement  after receipt of
the Purchase Price,  the Company shall (a) deliver to the Investor,  or instruct
its transfer agent to deliver to the Investor, a certificate,  registered in the
Investor's name,  representing the Shares,  and (b) cause its outside counsel to
deliver  an  opinion to the  Investor,  dated as of the date of this  Agreement,
substantially to the effect of Exhibit A hereto.

<PAGE>


2.       Representations and Warranties of the Investor Regarding the Shares

         The Investor  hereby  represents  and warrants to the Company as of the
date of this Agreement as follows:

         2.1      High Degree of Risk

         There can be no  assurance  that the Company will be able to obtain its
projected goals, and the Company will need significant  additional capital to be
successful, which capital may not be readily available when and as needed.

         2.2      Professional Advice

         The Investor has obtained,  to the extent it deems  necessary,  its own
professional  advice with respect to the risks inherent in the investment in the
Shares,  the condition of the Company and the  suitability  of the investment in
the Shares in light of the Investor's financial condition and investment needs.

         2.3      Sophistication

         The Investor,  either alone or with the assistance of its  professional
advisors,  has such knowledge and  experience in financial and business  matters
that it is  capable  of  evaluating  the  merits  and  risks of the  prospective
investment in the Shares.

         2.4      Suitability

         The Investor has  adequate  net worth and means for  providing  for its
current  financial  needs and  contingencies  and has no need for  liquidity  of
investment  with respect to the Shares.  The  Investor's  overall  commitment to
investments that are illiquid or not readily marketable is not  disproportionate
to its net  worth,  and  investment  in the Shares  will not cause such  overall
commitment to become excessive.

         2.5      Access to Information

         The Investor has been given access to all  information  requested by it
regarding the Company, including, in particular, the current financial condition
of the Company and the risks associated therewith,  and has utilized such access
to its satisfaction for the purpose of obtaining  information  about the Company
and the Investor has either  attended or been given a reasonable  opportunity to
attend a meeting with  representatives  of the Company for the purpose of asking
questions of, and receiving  answers from, such  representatives  concerning the


                                       2
<PAGE>

terms and  conditions of the offering of the Shares and to obtain any additional
information,  to the  extent  reasonably  available,  necessary  to  verify  the
accuracy of information provided about the Company.

         2.6      Purchase Entirely for Own Account

         The Shares will be  acquired  for  investment  for the  Investor's  own
account,  not as a nominee or agent,  and not with a view to the distribution of
any part thereof. The Investor has no present intention of selling, granting any
participation in or otherwise  distributing the same in a manner contrary to the
Securities  Act of 1933,  as amended (the  "Act"),  or any  applicable  state or
foreign  securities or Blue Sky laws, and has no agreement or  arrangement  with
any person to sell,  transfer or grant  participations  to such person or to any
third person with respect to any of the Shares.

         2.7      Due Diligence

         The  Investor  has been solely  responsible  for its own due  diligence
investigation of the Company and the Company's business, and its own analysis of
the merits and risks of the investment made pursuant to this  Agreement,  and is
not relying on anyone  else's  analysis or  investigation  of the  Company,  its
business or the merits and risks of the Shares other than professionals employed
specifically  by the  Investor to assist the  Investor.  In taking any action or
performing  any role  relative to the  arranging  of the  investment  being made
pursuant to this  Agreement,  the  Investor has acted solely in its own interest
and not in the interest of any other person, and no other person has acted as an
agent or fiduciary for the Investor.

         2.8      Restricted Securities

         The Investor  realizes  that the sale of the Shares  hereunder  has not
been registered under the Act, that the Shares are  characterized  under the Act
as "restricted  securities," and,  therefore,  that the Shares cannot be sold or
transferred  unless they are subsequently  registered under the Act or unless an
exemption  from  such  registration  is  available.   The  Investor's  financial
condition  is such that it is not likely to need to dispose of any of the Shares
in the foreseeable  future. In this connection,  the Investor represents that it
is familiar with Rule 144 of the Securities and Exchange Commission (the "SEC"),
as presently in effect, and understands the resale  limitations  imposed thereby
and by the Act.



                                       3
<PAGE>

         2.9      Exemption Reliance

         The Investor has been advised that the Shares are not being  registered
under the Act or the applicable state securities laws, but are being offered and
sold pursuant to exemptions from such laws, and that the Company's reliance upon
such  exemptions  is  predicated  in  part  on  the  Investor's  representations
contained herein. The Investor represents that it has not been organized for the
specific purpose of investing in the Shares.

         2.10     Further Limitations on Disposition

(a)Without in any way limiting the representations set forth above, the Investor
further agrees not to make any  disposition of all or any portion of the Shares,
the shares of the Company's  common stock that would be issuable to the Investor
upon conversion of the Shares (the  "Conversion  Shares" and,  together with the
Shares, the "Securities"), unless and until

                   (i) there is then in effect a  registration  statement  under
the Act covering  such  proposed  disposition  and such  disposition  is made in
accordance with such registration statement; or

                  (ii) (A) if there is no  registration  statement under the Act
covering the proposed disposition,  the Investor shall have notified the Company
of the proposed disposition and shall have furnished the Company with a detailed
statement of the circumstances  surrounding the proposed disposition at least 30
days prior to said  disposition and (B) if reasonably  requested by the Company,
the Investor  shall have furnished the Company with an opinion of counsel (which
opinion  may  be  delivered  by the  Investor's  in-house  counsel),  reasonably
satisfactory to the Company, that such disposition will not require registration
of such Securities under the Act; or

                  (iii) the Company shall have been satisfied that such proposed
disposition  complies in all respects  with SEC Rule 144 or any  successor  rule
providing a safe harbor for such disposition without registration.

         (b) In addition to the foregoing  provisions of subsection  (a) of this
Section 2.10, if there is then in effect a registration  statement under the Act
covering a proposed disposition of any or all of the Securities by the Investor,
then in order to preserve an orderly market for the Company's  common stock, (A)
at least five business days prior to any such proposed disposition, the Investor
shall provide to the Company notice of such disposition;  (B) the Investor shall
provide  the Company or its agent an  opportunity  to arrange the sale to one or


                                       4
<PAGE>

more parties of the Securities  proposed to be transferred  and shall  cooperate
fully with the Company or such agent in such process  (including  discussions of
the terms of such sale with no more than two brokers  designated  by the Company
and to sell such  Securities  to one or both of such  brokers if an agreement is
reached);  and (C) if,  after  three  business  days  from the  date the  notice
referred  to in  this  subsection  is  received  by the  Company,  an  agreement
regarding  such a sale has not been  reached,  the  Investor may dispose of such
Securities  in any manner it so chooses  so long as such  disposition  is not in
violation of this Agreement.

         (c)   Notwithstanding   the   provisions   of  this  Section  2.10,  no
registration  statement or opinion of counsel  shall be necessary for a transfer
by the Investor to any wholly owned  subsidiary  of the Investor or of Johnson &
Johnson which is an accredited investor,  if the transferee agrees in writing to
be subject to the terms hereof,  to the same extent as if such  transferee  were
the Investor hereunder.  Whenever the restrictions  imposed by this Section 2.10
shall  terminate as herein  provided,  the holder of the  securities as to which
such restrictions have terminated shall be entitled to receive from the Company,
without expense,  one or more new certificates not bearing  restrictive  legends
and not containing any reference to the restrictions imposed by this Agreement.

         2.11     Domicile; Principal Place of Business

         The Investor  represents that it is domiciled in, and has its principal
place of business in, the  jurisdiction set forth in the first paragraph of this
Agreement.

         2.12     Legends

         It is understood that the certificate evidencing the Shares will bear a
legend as follows:

                  "The securities  evidenced by this  certificate  have not been
                  registered  under the Securities  Act of 1933, as amended,  of
                  the United  States of America (the "Act"),  or the  securities
                  laws of any  state of the  United  States of  America,  and no
                  interest in such securities may be sold,  offered,  pledged or
                  hypothicated in the United States of America,  its territories
                  or possessions,  or to a citizen, national, resident or entity
                  organized or chartered  under the laws of the United States of
                  America,  its territories or possessions,  unless (i) there is
                  an  effective   registration   statement  under  the  Act  and
                  applicable   state  securities  laws,  (ii)  this  corporation
                  receives an opinion of legal  counsel for the holders of these


                                       5
<PAGE>

                  securities  satisfactory to this corporation stating that such
                  transaction  is  exempt  from  registration  under the Act and
                  applicable  state  securities  laws, or (iii) this corporation
                  otherwise  satisfies  itself that such  transaction  is exempt
                  from registration."

         2.13     Acknowledgment

         The Investor, by executing below, acknowledges that it understands that
the Company is relying upon the accuracy and completeness of its representations
and  warranties  set forth in this  Section 2 in  deciding  whether  to sell the
Shares to the Investor and in complying  with the  Company's  obligations  under
applicable securities laws.

3.       Further Representations and Warranties of the Investor

         The Investor  hereby  represents  and warrants to the Company as of the
date of this Agreement as follows:

         3.1      Organization and Existence

         The Investor is a corporation  duly organized,  validly existing and in
good  standing  under the laws of the State of New Jersey and has all  requisite
power and authority to enter into and perform this Agreement.

         3.2      Authorization

         The  execution,  delivery  and  performance  by the  Investor  of  this
Agreement  and the  consummation  of the  transactions  contemplated  hereby are
within the corporate powers of the Investor and have been duly authorized by all
necessary corporate action on the part of the Investor.  This Agreement has been
duly and validly executed and delivered by the Investor and constitutes a legal,
valid and binding agreement of the Investor,  enforceable in accordance with its
terms  except as (a) the  enforceability  thereof may be limited by  bankruptcy,
insolvency or similar laws  affecting  creditors'  rights  generally and (b) the
availability  of equitable  remedies may be limited by equitable  principles  of
general applicability.

         3.3      Governmental Authorization

         No consent, approval or authorization of or designation, declaration or
filing with any  governmental  authority on the part of the Investor is required
in connection  with the valid  execution  and delivery of this  Agreement or the
purchase of the Shares.


                                       6
<PAGE>


         3.4      Noncontravention

         The  execution,  delivery  and  performance  by the  Investor  of  this
Agreement do not and will not, with or without the passage of time or the giving
of notice or both, (a) contravene or conflict with the articles of incorporation
or bylaws of the Investor;  (b) assuming compliance with the matters referred to
in Section 3.3 hereof,  contravene or conflict with or constitute a violation of
any  provision of any law,  regulation,  judgment,  injunction,  order or decree
binding upon or applicable  to the Investor;  (c) conflict with or result in any
breach of any of the terms, conditions or provisions of, or constitute a default
(or give rise to any right of termination,  cancellation or acceleration) under,
or result in the creation of any lien, security interest,  charge or encumbrance
upon any of the  properties or assets of the Investor  under any material  note,
indenture,  mortgage,  lease,  agreement,  contract,  purchase  order  or  other
instrument,  document or  agreement to which the Investor is a party or by which
it or any of its properties or assets is bound or affected.

         3.5      Finders' Fees

         There is no investment banker, broker, finder or other intermediary who
has been  retained by or is  authorized to act on behalf of the Investor and who
might be entitled to any fee or commission  from the Investor in connection with
the transactions contemplated by this Agreement.

         3.6      Financing

         The Investor has sufficient funds available to purchase the Shares.

4.       Representations and Warranties of the Company

         The Company  hereby  represents  and warrants to the Investor as of the
date of this Agreement as follows:

         4.1      Corporate Organization

         The Company is a corporation  duly organized,  validly  existing and in
good standing  under the laws of the State of Washington  and is qualified to do
business as a foreign  corporation in each jurisdiction  where the failure to so
qualify  would have a Material  Adverse  Effect (as  defined  hereinafter).  The
Company has all  requisite  power and  authority  to enter into and perform this
Agreement  and to own its  properties  and to carry on its business as now being
conducted.

                                       7
<PAGE>


         4.2      Corporate Authorization

         The  execution,  delivery  and  performance  by  the  Company  of  this
Agreement  and the  consummation  of the  transactions  contemplated  hereby are
within the corporate  powers of the Company and have been duly authorized by all
necessary  corporate action on the part of the Company.  This Agreement has been
duly and validly  executed and delivered by the Company and constitutes a legal,
valid and binding  agreement of the Company,  enforceable in accordance with its
terms  except as (a) the  enforceability  thereof may be limited by  bankruptcy,
insolvency or similar laws  affecting  creditors'  rights  generally and (b) the
availability  of equitable  remedies may be limited by equitable  principles  of
general applicability.

         4.3      Governmental Authorization

         No consent, approval or authorization of or designation, declaration or
filing with any  governmental  authority  on the part of the Company is required
for or in connection with the valid execution and delivery of this Agreement, or
the valid and lawful  authorization,  issuance,  offer, sale and delivery of the
Securities,  or the  consummation of the  transactions  contemplated  hereunder,
except for the  qualification  or registration  (or taking such action as may be
necessary  to  secure  an  exemption  from  qualification  or  registration,  if
available) of the offer and sale of the Securities  under all  applicable  state
securities laws.

         4.4      Noncontravention

         The  execution,  delivery  and  performance  by  the  Company  of  this
Agreement do not and will not, with or without the passage of time or the giving
of  notice  or  both,   (a)   contravene   or  conflict  with  the  articles  of
incorporation,  as amended,  or bylaws of the Company;  (b) assuming  compliance
with the matters referred to in Section 4.3 hereof,  contravene or conflict with
or  constitute a violation of any  provision of any law,  regulation,  judgment,
injunction,  order or decree  binding upon or  applicable  to the  Company;  (c)
conflict  with or  result  in any  breach  of any of the  terms,  conditions  or
provisions  of,  or  constitute  a  default  (or  give  rise  to  any  right  of
termination,  cancellation or acceleration)  under, or result in the creation of
any lien, security interest, charge or encumbrance upon any of the properties or
assets of the Company  under any  material  note,  indenture,  mortgage,  lease,
agreement,  contract, purchase order or other instrument,  document or agreement
to which  the  Company  is a party or by  which it or any of its  properties  or
assets is bound or affected. The business of the Company is not being conducted,
and shall not be conducted  through the date upon which all the Shares have been
converted  into shares of the Company's  common stock,  in violation of any law,
ordinance  or  regulation  of  any  governmental  entity,  except  for  possible


                                       8
<PAGE>

violations  which either  singularly  or in the aggregate do not have a Material
Adverse Effect.

         4.5      Authorization and Validity of the Shares

         The Shares have been duly  authorized and, when issued and delivered to
and paid for by the Investor pursuant to this Agreement, will be validly issued,
fully paid and nonassessable,  and such shares are free of preemptive or similar
rights. All outstanding securities of the Company were issued in compliance with
applicable   federal  and  state  securities  laws.  Upon  consummation  of  the
transactions  contemplated  hereby, good and valid title to the Shares will pass
to the Investor,  free and clear of any encumbrances,  liens, claims, charges or
assessments of any nature whatsoever. Upon their issuance in accordance with the
Company's  Articles of  Incorporation,  as amended,  good and valid title to the
Conversion Shares will pass to the Investor, free and clear of any encumbrances,
liens,  claims,  charges or assessments of any nature whatsoever.  The Preferred
Stock shall have the rights,  privileges,  and  preferences  as set forth in the
Amendment to the Company's  Articles of Incorporation  (the  "Amendment") in the
form attached to this Agreement as Exhibit B.

         4.6      Capitalization

         As of the date  hereof,  the  authorized  capital  stock of the Company
consists of (i) 60,000,000 shares of Common Stock of which 17,293,519 shares are
outstanding,  and (ii)  3,000,000  shares of Preferred  Stock,  of which 600,000
shares have been designated  Series A Junior  Participating  Preferred Stock, of
which none are  outstanding;  1,120,000  shares have been  designated as $2.4375
Convertible  Exchangeable  Preferred  Stock,  Series  1, of  which  208,240  are
outstanding;  50,000  shares  have  been  designated  as  Series  2  Convertible
Preferred  Stock, of which 5,167 are  outstanding;  and 120,000 shares have been
designated  as  Series 3  Convertible  Preferred  Stock,  of which  118,780  are
outstanding.  All such outstanding shares have been validly issued and are fully
paid and nonassessable. The Company has reserved 1,000 shares of Preferred Stock
for issuance hereunder. The Company has, and at all times shall have, authorized
and reserved for issuance a sufficient  number of shares of the Company's common
stock as necessary to provide for the  conversion of the Shares and the Dividend
Shares.  The Conversion  Shares will, upon issuance in accordance with the terms
of the Company's  Articles of  Incorporation,  as amended,  be duly  authorized,
validly  issued  and  outstanding,   fully  paid  and  nonassessable,   and  the
certificates representing the same will be duly and validly authorized, executed
and delivered by the Company.

                                       9
<PAGE>


         4.7      Nasdaq National Market; Listing

         The Company's  common stock is quoted on the Nasdaq National Market and
the Company is in compliance with the applicable provisions of Schedule D to the
By-laws of the National Association of Securities Dealers, Inc.

         4.8      Finders' Fees

         There is no investment banker, broker, finder or other intermediary who
has been  retained by or is  authorized  to act on behalf of the Company and who
might be entitled to any fee or commission  from the Company in connection  with
the transactions contemplated by this Agreement.

         4.9      Financial Statements

         Each of the  audited  consolidated  balance  sheets and  statements  of
operations  and cash flow for the Company  contained  in the Public  Reports (as
defined below) (collectively, the "Financial Statements") are in accordance with
the books and records of the  Company,  have been  prepared in  accordance  with
generally  accepted  accounting  principles,  consistently  applied,  and fairly
present, in all material respects, the financial position, results of operations
and cash flows of the  Company as of each such date and for each of the  periods
covered  thereby,  except  that such  summary  statements  are subject to normal
year-end adjustments.

         4.10     Absence of Undisclosed Liabilities

         Except  as and to the  extent  reflected  or  stated  in the  Financial
Statements,  the Company has no debts, liabilities or obligations of any nature,
whether accrued, absolute, assigned or otherwise,  whether due or to become due,
other than incurred in the ordinary course of business.

         4.11     Absence of Certain Developments

         Since June 30, 1997,  except as disclosed in the  Financial  Statements
and except for continuing  operating losses,  there has been no (i) change which
may  result  in a  material  adverse  effect  on  the  condition,  financial  or
otherwise,  of the Company or its  assets,  liabilities,  properties,  business,
operations, condition or prospects generally (a "Material Adverse Effect"), (ii)
declaration, setting aside or payment of any dividend or other distribution with
respect to the capital stock of the Company  except  dividends set aside or paid
by the Company with respect to Convertible  Exchangeable Preferred Stock, Series
1, Series 2 Convertible Preferred Stock or Series 3 Convertible Preferred Stock,
or (iii) loss, destruction or damage to any property of the Company,  whether or
not insured, which has or may have a Material Adverse Effect.

                                       10
<PAGE>


         4.12     Litigation

         Except as disclosed in the Company's  Quarterly Report on Form 10-Q for
the quarter ended June 30, 1997, there is no claim,  arbitration,  action, suit,
proceeding or  investigation  pending,  or to the best knowledge of the Company,
threatened  against the Company,  which questions the validity of this Agreement
or any other  agreement  entered  into by the  Company in  connection  with this
Agreement  or the right of the Company to enter into any such  agreements  or to
consummate  the  transactions  contemplated  hereby or  thereby,  or which might
result,  in a  Material  Adverse  Effect,  or any change in the  current  equity
ownership  of the  Company.  The  Company  is not a party to, or  subject to the
provisions of, any order, writ,  injunction,  judgment or decree of any court or
governmental  agency or  instrumentality  which  would have a  Material  Adverse
Effect.

         4.13     Insurance

         The Company maintains in full force such types and amounts of insurance
issued by  issuers of  recognized  responsibility  insuring  the  Company,  with
respect to its liability,  workers'  compensation,  business and properties,  in
such amounts and against  such losses and risks as are  customary in the case of
corporations engaged in businesses and having  circumstances  similar to that of
the Company.

         4.14     Environmental and Safety Laws

         To the best of its knowledge,  the Company is in compliance  with every
applicable   statute,   law  or  regulation   relating  to  the  environment  or
occupational health and safety,  except where the failure to so comply would not
individually  or in the aggregate have a Material  Adverse  Effect,  and, to the
best of the Company's knowledge,  no material expenditures are required in order
to comply with any such existing statute, law or regulation.

         4.15  Securities Laws

         Assuming that the Investor's  representations and warranties  contained
in Section 2 of this  Agreement  are and  continue to be true and  correct,  the
offer, issuance and sale to the Investor of the Shares and the Conversion Shares
are  and  will  be  exempt  from  the  registration   and  prospectus   delivery
requirements  of the Act, and have been  registered  or qualified (or are exempt
from  registration  and  qualification)   under  the  registration,   permit  or
qualification requirements of all applicable state securities laws.


                                       11
<PAGE>


5.       Public Reports

         The Company has  provided to the Investor  true and complete  copies of
all reports,  schedules,  forms,  statements  and other  documents  (the "Public
Reports") filed by the Company with the SEC under the Securities Exchange Act of
1934,  as amended (the  "Exchange  Act"),  since  December 31, 1993.  The Public
Reports  include all the reports the Company has been required to file under the
Exchange  Act since  that date.  As of their  respective  dates,  (i) the Public
Reports complied in all material  respects with the requirements of the Exchange
Act and the rules and regulations promulgated  thereunder,  and (ii) none of the
Public Reports  contained any untrue  statement of a material fact or omitted to
state a material  fact  required to be stated  therein or  necessary in order to
make the statements therein not misleading.

6.       [Intentionally deleted.]

7.       Registration Rights

         7.1      Certain Definitions

         As used in this Section 7, the following terms shall have the following
respective meanings:

         (a)      "Form S-3" shall mean Form S-3 issued by the SEC or any sub-
stantially similar form then in effect.

         (b)      "Holder" shall mean the Investor.

         (c) "Milestone  Date" shall mean the date upon which Janssen shall have
made  payment to the Company of the amount  specified  in Section  4.2(b) of the
License Agreement.

         (d)  "Register,"  "Registered"  and  "Registration"  shall  refer  to a
registration  effected  by  preparing  and filing a  registration  statement  in
compliance with the Act (the "Registration  Statement") and pursuant to Rule 415
under the Act or any  successor  rule  providing  for offering  securities  on a
continual  basis,  and the declaration or ordering of the  effectiveness of such
Registration Statement.

         (e)      "Registrable Securities" shall mean the Conversion Shares.


                                       12
<PAGE>


         (f)  "Registration  Expenses"  shall mean all expenses  incurred by the
Company in complying with this Section 7,  including,  without  limitation,  all
federal  and  state  registration,   qualification  and  filing  fees,  printing
expenses,  fees and disbursements of counsel for the Company,  Blue Sky fees and
expenses,  and the expense of any special audits  incident to or required by any
such registration.

         (g)  "Restriction  Termination  Date" shall mean,  with  respect to any
Registrable  Securities,  the  earliest  of (i) the date that  such  Registrable
Securities  shall have been  Registered  and sold or  otherwise  disposed  of in
accordance  with the intended  method of  distribution  by the seller or sellers
thereof  set  forth in the  Registration  Statement  covering  such  Registrable
Securities or transferred in compliance with SEC Rule 144, (ii) the date that an
opinion of counsel to the Company which  counsel shall be reasonably  acceptable
to the Holder  containing  reasonable  assumptions shall have been rendered and,
based upon such  opinion,  the legend  referred to in Section  2.12 hereof shall
have  been  removed,  and  (iii)  the  second  anniversary  of the  date of this
Agreement.

         (h)  "Selling  Expenses"  shall  mean all  underwriting  discounts  and
selling commissions applicable to the sale of Registrable Securities pursuant to
this Agreement and all fees and disbursements of counsel for the Holder.

         7.2      Request for Registration

         (a) Upon the terms and subject to the  conditions of this Section 7, at
any time within the period  commencing on the earlier of (i) the Milestone  Date
and (ii) 12 months from the date of this Agreement and ending on the Restriction
Termination  Date,  the Holder may,  from time to time during such  registration
period,  request the Company in writing to effect a Registration on any form for
which the Company then  qualifies  and which  counsel for the Company shall deem
appropriate and available for an offering of Registrable Securities. The Company
will  promptly  give notice of the proposed  Registration  to the Holder and, as
soon as practicable  after receipt of such notice,  the Company shall proceed to
file a Registration  Statement covering all of the Registrable  Securities to be
registered  thereunder in accordance  with the intended  method of  distribution
which the Holder  requests  to be  registered  within 15 days  after  mailing of
notice by the Company. The Company shall exercise its best efforts to cause such
Registration  Statement to be declared  effective by the SEC as soon as possible
after  such  filing and in any event  within 90 days of the date of filing  such
Registration   Statement,   although  the  Company   cannot   assure  that  such
Registration Statement will in fact be declared effective by the SEC within such
90 day period.  The  Registration  Statement  (and each  amendment or supplement
thereto)  shall not contain any untrue  statement of a material  fact or omit to
state a material  fact required to be stated  therein,  or necessary to make the
statements  therein,  in light of the circumstances in which they were made, not


                                       13
<PAGE>

misleading.  The Company  hereby  agrees to file in a timely  manner all reports
required  under the Exchange  Act during the  registration  period.  The Company
shall be obligated to effect only one Registration pursuant to this Agreement.

         (b)      Notwithstanding the foregoing,

                  (i)  the  Company   shall  not  be   obligated   to  effect  a
Registration  pursuant to this Section 7.2 during the period  starting  with the
date 30 days prior to the Company's good faith  estimated date of filing of, and
ending on the earlier of (A) the date which is 90 days after the effective  date
of,  and (B) the date  which is 150 days  after the  filing  of, a  Registration
Statement  pertaining to an  underwritten  public offering of securities for the
account of the  Company,  provided  that the  Company  diligently  pursues  such
Registration; and

                  (ii) the  Company  shall  not be  obligated  to  register  any
Registrable  Securities,  if, in the  reasonable  opinion  of its  counsel,  all
Registrable  Securities  may be sold in the open market  within a 90-day  period
under SEC Rule 144 without registration under the Act.

         7.3      Blue Sky

         In the  event  of any  Registration  pursuant  to this  Section  7, the
Company will  exercise its best efforts to Register and qualify the  Registrable
Securities covered by the Registration  Statement under such other securities or
Blue Sky laws of such  jurisdictions  as shall be  reasonably  requested  by the
Holder for the  distribution of such  securities;  provided,  however,  that the
Company  shall not be  required  (a) if the  Company  is  listed  on the  Nasdaq
National Market, to register or qualify in any states or  jurisdictions,  except
New York, that do not have a Nasdaq National  Market  securities  exemption from
registration  and  qualification,  and (b) to qualify to do business,  to file a
general  consent to service of process or to subject  itself to  taxation in any
state or jurisdiction in which it is not now qualified. The Company will furnish
to the Holder  written  advice of its counsel  with respect to  registration  or
exemption of such Registrable Securities in such jurisdictions.

         7.4      Expenses of Registration

         All Registration Expenses shall be borne by the Company and all Selling
Expenses shall be borne by the Holder of the Registrable Securities.


                                       14
<PAGE>

         7.5      Registration Procedures

                  7.5.1    Advice by Company

         The  Company  will keep the  Holder  advised as to the  initiation  and
completion of such Registration.  The Company,  if requested by the Holder, will
furnish to the Holder,  prior to filing with the SEC, a copy of the Registration
Statement  proposed  to be so filed.  The  Company  will (a) use all  reasonable
efforts  to  keep  such  Registration  effective  until  (i)  in the  case  of a
Registration  on Form S-3,  the  earlier of (A) the date on which the Holder has
completed the distribution described in the Registration Statement,  and (B) two
years from the date of this Agreement,  or (ii) in the case of a Registration on
any  form  other  than  Form  S-3,  120  days  from  the  effective  date of the
Registration  Statement and (b) furnish (i) promptly  after the same is prepared
and distributed, filed with the SEC, or received by the Company, one copy of the
Registration  Statement and each amendment and supplement thereto, and (ii) such
number of prospectuses (including a preliminary  prospectus,  and all amendments
and  supplements  thereto)  and such other  documents as the Holder from time to
time may reasonably request.

                  7.5.2    Amendments

         The Company will promptly prepare and file with the SEC such amendments
and  prospectus  supplements,   including  post-effective   amendments,  to  the
Registration  Statement  as may be necessary  or  appropriate,  and use its best
efforts to have such post-effective amendments declared effective as promptly as
practicable;  cause the related  prospectus to be supplemented by any prospectus
supplement,  and as so  supplemented,  to be filed with the SEC;  and notify the
Holders  of any  securities  included  in such  Registration  Statement  and the
underwriter  thereof,  if any,  promptly  when a  prospectus  or any  prospectus
supplement or post-effective amendment must be filed or has been filed and, with
respect to any post-effective amendment, when the same has become effective, and
make the same available to the Holder and any underwriter.

                  7.5.3    Other Agreements and Actions

         The  Company  will  enter  into  customary  agreements   (including  an
underwriting  agreement  in customary  form) and take such other  actions as are
reasonably  required  in  order  to  expedite  or  facilitate  the  sale of such
Registrable Securities.



                                       15
<PAGE>

                  7.5.4    Listing of Securities

         The  Company  will use all  reasonable  efforts  to (i)  cause all such
Registrable Securities to be listed on each securities exchange on which similar
securities issued by the Company are then listed, or (ii) secure designation and
quotation  of all such  Registrable  Securities  on the Nasdaq  National  Market
System or, if despite the Company's best efforts to satisfy the preceding clause
(i) or (ii), the Company is unsuccessful is satisfying the preceding  clause (i)
or  (ii),  to  secure  listing  on a  national  securities  exchange  or  Nasdaq
authorization  and  quotation  for such  securities  and,  without  limiting the
generality  of the  foregoing,  to  arrange  for at least two  market  makers to
register with the National  Association of Security  Dealers,  Inc. as such with
respect to such Registrable Securities.

                  7.5.5        Piggyback Registration

         If the Company proposes to file a Registration  Statement under the Act
with respect to an  underwritten  offering of the Company's  common stock at any
time within the period  commencing  one year from the date of this Agreement and
ending  on the  earlier  of (a)  the  second  anniversary  of the  date  of this
Agreement and (b) the date of a request pursuant to Section 7.2 hereof to effect
a  Registration  (i) for the  Company's own account  (other than a  Registration
Statement on Form S-4 or Form S-8 (or any similar or substitute form that may be
adopted  by the SEC)) or (ii) for the  account  of any of its  holders of common
stock, then the Company shall give written notice of such proposed filing to the
Holder as soon as practicable (but in no event less than 10 business days before
the  anticipated  filing  date),  and such  notice  shall  offer the  Holder the
opportunity to Register such number of shares of  Registrable  Securities as the
Holder may  request on the same terms and  conditions  as the  Company's  common
stock. If the Company proposes to file a Registration Statement under the Act on
Form S-4 to effect an offer to existing  shareholders  to exchange the Company's
common stock not registered  under the Act for common stock registered under the
Act (other than  pursuant to this Section 7), the Company shall offer the Holder
the opportunity to exchange its Registrable  Securities for common stock in such
offer on the same terms and conditions as the Company's other  shareholders.  If
the Holder  exchanges  Registrable  Securities for the Company's common stock in
such offer, such common stock shall not be deemed  Registrable  Securities.  The
Company  shall not be required  under this Section  7.5.5 to Register any of the
Holder's securities in connection with an underwritten offering of the Company's
securities  unless the Holder  accepts the terms of the  underwriting  as agreed
upon between the Company and the  underwriters  selected by it, and then only in
such  quantity  as  will  not,  in the  opinion  of the  managing  underwriters,
interfere with the successful  marketing of the offering by the Company.  If the


                                       16
<PAGE>

managing  underwriters  advise that the  inclusion in such  registration  of all
Registrable  Securities and securities held by other holders  ("Other  Piggyback
Securities")  requested to be registered  would  interfere  with the  successful
marketing of securities that the Company  proposes to offer for its own account,
then all  securities  for sale by the Company  shall  first be included  and the
number of Registrable Securities and Other Piggyback Securities to be registered
shall be reduced pro rata among all holders  thereof in proportion to the voting
rights of all outstanding shares held by such holders.

         7.6      Information Furnished by the Holder

         It shall be a condition  precedent to the Company's  obligations  under
this  Agreement  that  the  Holder  furnish  to  the  Company  in  writing  such
information  regarding  the Holder and the  distribution  proposed  by it as the
Company may reasonably request.

         7.7      Indemnification

                  7.7.1    Company's Indemnification of the Holder

         The Company will  indemnify and hold  harmless the Holder,  each person
who  controls  the  Holder  (within  the  meaning  of the Act) and each of their
officers,   directors   and   constituent   partners,   with  respect  to  which
Registration,  qualification  or compliance of  Registrable  Securities has been
effected  pursuant to this  Agreement,  against all claims,  losses,  damages or
liabilities (or actions with respect thereto) to the extent such claims, losses,
damages,  liabilities  or  actions  arise  out of or are based  upon any  untrue
statement (or alleged  untrue  statement)  of a material  fact  contained in any
prospectus  or  any  related   Registration   Statement  incident  to  any  such
Registration, qualification or compliance, or any omission (or alleged omission)
to state therein a material  fact required to be stated  therein or necessary to
make the statements  therein not misleading,  or any violation by the Company of
any rule or regulation  promulgated  under the Act applicable to the Company and
relating to action or inaction  required of the Company in  connection  with any
such Registration; and the Company will reimburse the Holder and each person who
controls  the Holder for any legal and other  expenses  reasonably  incurred  in
connection  with  investigating  or  defending  any such  claim,  loss,  damage,
liability or action;  provided,  however,  that the indemnity  contained in this
Section  7.7.1 shall not apply to amounts paid in  settlement of any such claim,
loss, damage,  liability or action if settlement is effected without the consent
of the Company  (which consent shall not be  unreasonably  withheld or delayed);
and provided,  further,  that the Company will not be liable in any such case to
the extent that any such claim, loss, damage,  liability or action arises out of


                                       17
<PAGE>

or is based upon any untrue statement or omission based upon written information
furnished  to the  Company  by the  Holder  or  controlling  person  for  use in
connection with the offering of securities of the Company.  Notwithstanding  the
above,  the  foregoing  indemnity  agreement is subject to the  condition  that,
insofar as it relates to any such untrue  statement,  alleged untrue  statement,
omission or alleged  omission made in a preliminary  prospectus,  such indemnity
agreement  shall not inure to the  benefit  of the Holder if a copy of the final
prospectus was not furnished to the person asserting the loss, liability,  claim
or damage at or prior to the time such  action is required by the Act and if the
final  prospectus  corrected the untrue  statement or omission or alleged untrue
statement or omission.

                  7.7.2    Holder's Indemnification of Company

         The  Holder  will,  if  Registrable  Securities  held by the Holder are
included in the securities as to which a Registration is being effected pursuant
to this Agreement, indemnify and hold harmless the Company, each of its officers
and directors and each person who controls the Company within the meaning of the
Act against all claims, losses, damages and liabilities (or actions with respect
thereto)  arising out of or based upon any untrue  statement (or alleged  untrue
statement) of a material fact  contained in any such  Registration  Statement or
related  prospectus,  or any 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 the Holder  will  reimburse  the Company and such
directors,  officers,  partners,  persons or control  persons  for any legal and
other expenses reasonably incurred in connection with investigating or defending
any such claim, loss,  damage,  liability or action, in each case to the extent,
but only to the extent, that such untrue statement (or alleged untrue statement)
or omission  (or alleged  omission)  is made in such  Registration  Statement or
prospectus in reliance upon and in conformity with written information furnished
to the Company by the Holder and stated to be specifically for use in connection
with the offering of  Securities  of the Company;  provided,  however,  that the
indemnity  contained  in this  Section  7.7.2 shall not apply to amounts paid in
settlement of any such claim, loss, damage, liability or action if settlement is
effected  without  the  consent  of  the  Holder  (which  consent  shall  not be
unreasonably withheld or delayed).

                  7.7.3    Indemnification Procedure

         Promptly after receipt by an  indemnified  party under this Section 7.7
of notice of the commencement of any action,  such indemnified  party will, if a
claim with  respect  thereto is to be made against an  indemnifying  party under
this Section 7.7, notify the  indemnifying  party in writing of the commencement
thereof and generally  summarize such action.  The indemnifying party shall have
the right to participate  in and to assume the defense of such claim,  and shall


                                       18
<PAGE>

be entitled to select counsel for the defense of such claim with the approval of
any  parties   entitled  to   indemnification,   which  approval  shall  not  be
unreasonably  withheld.  Notwithstanding  the  foregoing,  the party entitled to
indemnification  shall  have the right to employ  separate  counsel  (reasonably
satisfactory to the  indemnifying  party) to participate in the defense thereof,
but the  fees  and  expenses  of  such  counsel  shall  be the  expense  of such
indemnified party unless the named parties to such action or proceedings include
both the indemnifying party and the indemnified party and the indemnifying party
or such indemnified  party shall have been advised by counsel that there are one
or more legal defenses available to it which are different from or additional to
those  available to the  indemnifying  party (in which case, if the  indemnified
party  notifies  the  indemnifying  party in  writing  that it  elects to employ
separate  counsel at the  reasonable  expense  of the  indemnifying  party,  the
indemnifying party shall not have the right to assume the defense of such action
or proceeding on behalf of the  indemnified  party, as the case may be, it being
understood,  however,  that the indemnifying party shall not, in connection with
any such action or  proceeding or separate or  substantially  similar or related
action or  proceeding in the same  jurisdiction  arising out of the same general
allegations or circumstances,  be liable for the reasonable fees and expenses of
more than one separate  counsel at any time for the  indemnifying  party and all
indemnified  parties,  which  counsel  shall be  designated  in  writing  by the
Holder). If the indemnifying party withholds consent to a settlement or proposed
settlement by the  indemnified  party,  it shall  acknowledge to the indemnified
party its indemnification obligations hereunder.

                  7.7.4    Contribution

         If the  indemnification  provided  for in  this  Section  7.7  from  an
indemnifying party is unavailable to an indemnified party hereunder with respect
to any claims, losses, damages, liabilities and actions referred to herein, then
the indemnifying  party, in lieu of indemnifying such indemnified  party,  shall
contribute to the amount paid or payable by such  indemnified  party as a result
of such losses, claims,  damages,  liabilities or expenses in such proportion as
is  appropriate  to reflect the  relative  fault of the  indemnifying  party and
indemnified party in connection with the statements or omissions which result in
such losses,  claims,  damages,  liabilities  or expenses,  as well as any other
relevant equitable considerations. The relative fault of such indemnifying party
and  indemnified  party shall be determined by reference to, among other things,
whether  the  untrue or  alleged  untrue  statement  of a  material  fact or the
omission or alleged  omission to state a material  fact  relates to  information
supplied  by such  indemnifying  party or  indemnified  party  and that  party's
relative intent, knowledge,  access to information supplied by such indemnifying
party or indemnified  party and opportunity to correct or prevent such statement


                                       19
<PAGE>

or  omission.  The amount  paid or payable by a party as a result of the losses,
claims,  damages,  liabilities and expenses referred to above shall be deemed to
include any legal or other fees or expenses reasonably incurred by such party in
connection  with  investigating  or defending  any action,  suit,  proceeding or
claim.

         7.8      Transfer of Rights

         The right to cause  the  Company  to  Register  Registrable  Securities
granted by the Company to the Holder under this Section 7 may not be assigned to
any other person  except a permitted  transferee  described  in Section  2.10(c)
hereof.

         7.9      No-Action Letter or Opinion of Counsel in Lieu of Registration

         Notwithstanding  anything else in this Agreement,  if the Company shall
have obtained  from the SEC a "no-action"  letter in which the SEC has indicated
that it will take no action if, without  Registration  under the Act, the Holder
disposes of Registrable  Securities covered by any request for Registration made
under this  Section 7 in the  specific  manner in which the Holder  proposes  to
dispose  of the  Registrable  Securities  included  in  such  request  (such  as
including,  without limitation,  inclusion of such Registrable  Securities in an
underwriting  initiated  by either  the  Company  or the  Holder),  or if in the
opinion of counsel for the Company concurred in by counsel for the Holder, which
concurrence shall not be unreasonably withheld, no Registration under the Act is
required  in  connection  with  such  disposition,  the  Registrable  Securities
included in such  request  shall not be  eligible  for  Registration  under this
Agreement; provided, however, that any Registrable Securities not so disposed of
shall  be  eligible  for  Registration  in  accordance  with  the  terms of this
Agreement with respect to other proposed  dispositions to which this Section 7.9
does not apply.

8.       Miscellaneous

         8.1      Notices

         All  notices,   requests  and  other  communications  to  either  party
hereunder shall be in writing (including telex, telecopy or similar writing) and
shall be given,

                                       20
<PAGE>

                  if to the Company, to:

                           NeoRx Corporation
                           410 West Harrison Street
                           Seattle, Washington  98119-4007
                           Fax:  (206) 284-7112
                           Attn:  President

                  if to the Investor, to:

                           Johnson & Johnson Development Corporation
                           One Johnson & Johnson Plaza
                           New Brunswick, NJ 08933-7003
                           Fax:  (908) 247-5309
                           Attn:  President

                  with a copy to:

                           Office of General Counsel
                           Johnson & Johnson
                           One Johnson & Johnson Plaza
                           New Brunswick, NJ 08933
                           Fax:  (908) 524-2788

         8.2      Amendments; No Waivers

         (a) Any  provision of this  Agreement  may be amended or waived if, and
only if, such  amendment  or waiver is in writing and signed,  in the case of an
amendment,  by the Investor and the Company or, in the case of a waiver,  by the
party against whom the waiver is to be effective.

         (b) No failure or delay by either party in exercising any right,  power
or privilege hereunder shall operate as a waiver thereof nor shall any single or
partial  exercise  thereof preclude any other or further exercise thereof or the
exercise of any other right, power or privilege.  The rights and remedies herein
provided  shall be  cumulative  and not  exclusive  of any  rights  or  remedies
provided by law.

         8.3      Expenses

         All costs and expenses incurred in connection with this Agreement shall
be paid by the party  incurring  such cost or  expense,  except as  provided  in
Section 7 hereof with respect to Registration Expenses.

                                       21
<PAGE>


         8.4      Successors and Assigns

         The provisions of this Agreement shall be binding upon and inure to the
benefit of the parties  hereto and their  respective  successors  and  permitted
assigns;  provided that, except as set forth in Section 2.10(c) hereof,  neither
party  may  assign,  delegate  or  otherwise  transfer  any  of  its  rights  or
obligations under this Agreement without the consent of the other party hereto.

         8.5      Governing Law

         The Investor agrees that this Agreement shall be enforced, governed and
construed  in  all  respects  in  accordance  with  the  laws  of the  State  of
Washington,  and that the rights,  powers and duties set forth  herein  shall be
binding upon the Investor and its  successors and permitted  assigns,  and shall
inure to the benefit of its successors and permitted assigns.

         8.6      Counterparts; Effectiveness

         This  Agreement  may be signed in any number of  counterparts,  each of
which shall be an original,  with the same effect as if the  signatures  thereto
and hereto were upon the same instrument.  This Agreement shall become effective
when each party hereto shall have  received a  counterpart  hereof signed by the
other party hereto.

         8.7      Entire Agreement

         This Agreement  constitutes  the entire  agreement  between the parties
with respect to the subject matter hereof and  supersedes all prior  agreements,
understandings and negotiations, both written and oral, between the parties with
respect to the subject matter of this Agreement. No representation,  inducement,
promise, understanding, condition or warranty not set forth herein has been made
or relied upon by either party hereto.  Neither this Agreement nor any provision
hereof is intended to confer upon any person  other than the parties  hereto any
rights or remedies hereunder.

         8.8      Captions

         The captions  herein are included for convenience of reference only and
shall be ignored in the construction or interpretation hereof.

                                       22
<PAGE>


         8.9      Survival

         Notwithstanding  any investigation made by any party to this Agreement,
all covenants,  agreements,  representations  and warranties made by the Company
and  the  Investor  herein  and in the  certificates  for the  Shares  delivered
pursuant hereto shall survive the execution of this  Agreement,  the delivery to
the Investor of the Shares being purchased and the payment therefor.

         8.10     Lock-Up Agreement

         The Investor  agrees that,  if requested by the Company in  conjunction
with an  underwritten  public  offering,  the Investor will enter into a written
agreement that it will not,  directly or indirectly,  offer,  sell,  contract to
sell,  grant any option to  purchase,  make any short sale,  pledge or grant any
interest in, or otherwise  dispose of,  transfer or make a  distribution  of any
shares of the  Company's  common  stock for a period of 180 days  after the date
such public offering is declared effective by the SEC; provided that the Company
may only "lock up" the Investor  twice  pursuant to this Section 8.10 so long as
more than 364 days have elapsed  between the first and second requests for "lock
ups"; and, provided further,  that all officers and directors of the Company and
all other  persons with  registration  rights enter into  arrangements  with the
Company substantially similar to the provisions of this Section 8.10.



         8.11     Publicity

         Neither  party shall  originate  any  publicity,  news release or other
public  announcement,  written or oral,  containing  the name of the other party
(or, in the case of any  publicity,  news release or other  public  announcement
originated  by the  Company,  any  reference  to Johnson & Johnson or any wholly
owned subsidiary or affiliate  thereof)  relating to the performance  under this
Agreement  or the  existence  of any  arrangement  between  the  Company and the
Investor,  without the prior written  consent of the other party (which  consent
shall be deemed to have been given if the party being requested to consent fails
to respond  within  three (3)  business  days of  receipt  of a written  request
therefor),   except  where  such   publicity,   news  release  or  other  public
announcement is required by law; provided that in such event, the Investor shall
be consulted by the Company in connection with any such publicity,  news release
or other public  announcement  prior to its release and shall be provided with a
copy thereof.

                                       23
<PAGE>


         8.12     Further Assurances

         Each party shall do and perform, or cause to be done and performed, all
such  further  acts and  things,  and shall  execute  and deliver all such other
agreements,  certificates,  instruments  and  documents,  as the other party may
reasonably  request in order to carry out the intent and accomplish the purposes
of this Agreement and the consummation of the transactions contemplated hereby.



         IN WITNESS WHEREOF,  the parties hereto have executed this Agreement as
of the date first written above.

                               NEORX CORPORATION



                               /s/ Richard L. Anderson
                                   ------------------------
                               By     Richard L. Anderson
                               Its    Senior Vice President



                               JOHNSON & JOHNSON DEVELOPMENT CORPORATION

                               /s/ Ting Pau Oei
                                   -------------------------
                               By     Ting Pau Oei
                               Its    Vice President




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