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                                                                    EXHIBIT 10.1

                           PSMA SUBLICENSE AGREEMENT

                                 BY AND BETWEEN

                               CYTOGEN CORPORATION

                                       AND

                         NORTHWEST BIOTHERAPEUTICS INC.

                                      DATED

                                      AS OF

                                 AUGUST 28, 2000

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

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                           PSMA SUBLICENSE AGREEMENT

                           Dated as of August 28, 2000

        CYTOGEN CORPORATION ("Cytogen"), a Delaware corporation, having its
place of business at 600 College Road East, Princeton, New Jersey 08540 and
NORTHWEST BIOTHERAPEUTICS INC. ("NWBio"), a Delaware corporation, having its
principal place of business at 2203 Airport Way South, Suite 200, Seattle,
Washington 98134, hereby agree as follows:

        1. BASIS FOR AGREEMENT. The following chronology and purposes form the
basis for the agreements hereunder:

                1.1 MISROCK'S SPONSORSHIP OF RESEARCH ON MOAB 7E11. At the
request of Dr. Gerald P. Murphy, then Director of Roswell Park Memorial
Institute, Buffalo, New York, S. Leslie Misrock ("Misrock"), who subsequently
founded Prostagen Inc. ("Prostagen"), financially sponsored the research of Dr.
Julius S. Horoszewicz which led to the discovery of MoAb 7E11, one subclone of
which is MoAb 7E11-C5 and another subclone is 7E11-C5.3 which is denominated by
Cytogen as CYT-3511. The specific antibody utilized by Drs. Horoszewicz and
Murphy is described in Anticancer Research, 7:927-936 (1987), entitled
"Monoclonal Antibodies to a New Antigenic Marker in Epithelial Prostatic Cells
and Serum of Prostatic Cancer Patients." Additionally, Misrock was responsible
for Cytogen's acquisition of Horoszewicz patent rights covering MoAb 7E11 and
its subclones.

                1.2 SKICR'S USE OF MOAB 7E11-C5 TO ISOLATE PSMA GENE AND
PROTEIN. Cytogen furnished MoAb 7E11-C5 to Drs. Ron S. Israeli, Warren D. Heston
and William R. Fair at the Sloan-Kettering Institute For Cancer Research
("SKICR"), New York, New York, where these investigators isolated and
characterized the gene for prostate specific membrane antigen and subsequently
expressed and characterized the protein PSMA (as defined in Section 2) encoded
by such gene. The research by Drs. Israeli, Heston and Fair on the isolation and
characterization of the PSMA gene and protein is described in Cancer Research,
53:227-230 (1993), entitled "Cloning of a Complementary DNA Encoding a
Prostate-Specific Membrane Antigen."

                1.3 SKICR FILES FOR PATENT RIGHTS COVERING ITS PSMA
DEVELOPMENTS. With funding from Cytogen, SKICR filed a series of United States
and foreign counterpart patent applications on its PSMA developments in the
names of Drs. Israeli, Heston and Fair, on one of which applications United
States Patent No. 5,538,866 was granted on July 23, 1996. The `866 patent,
together with all United States patent applications and foreign counterparts
filed by or on behalf of SKICR covering its PSMA developments.

                1.4 CYTOGEN OBTAINS AND EXERCISES OPTION TO LICENSE SKICR PATENT
RIGHTS. Pursuant to the Option and License Agreement ("SKICR Agreement")
effective July 1, 1993, by and between Cytogen and SKICR, Cytogen was granted
the exclusive option to obtain an exclusive worldwide license to technology and
patent rights relating to SKICR's

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developments relating to PSMA for a term commencing July 1, 1993 and extending
until six (6) months after the issuance of the first United States patent on
this technology. Since the `866 patent was granted July 23, 1996, Cytogen's
option extended until January 23, 1997. Cytogen has advised and represented to
NWBio that it had exercised its option under the SKICR Agreement prior to
December 9, 1996.

                1.5 CYTOGEN SUBLICENSES PROSTAGEN. Pursuant to the PSMA
Therapeutics Sublicense Agreement (as defined in Section 2) Cytogen granted to
Prostagen the exclusive right and sublicense throughout the world, with the
right to grant sublicenses to others, under the SKICR Patent Rights, inter alia,

                        (a) to develop therapeutic products utilizing PSMA,
        prostate specific membrane peptides ("PSMP") containing any peptide
        sequence appearing within the PSMA protein, mimetopes of such peptides,
        DNA and/or RNA of PSMA and/or PSMP and/or mimetopes thereof, for the
        immunotherapeutic treatment of prostate cancer; and

                        (b) to produce, process or otherwise manufacture or have
        produced, processed or otherwise manufactured, to use or have used, to
        sell or have sold, any products for immunotherapy of prostate cancer (1)
        that contain PSMA, PSMP, mimetopes thereof, the DNA and/or RNA
        corresponding to such protein or peptides; (2) that are either (i)
        covered in whole or in part by a Valid Claim in the country in which
        such product is made, used or sold; or (ii) manufactured by using a
        process that is covered in whole or in part by a Valid Claim in the
        country in which such process is used; or (iii) used according to a
        method which is covered in whole or in part by a Valid Claim in the
        country in which such method is used; and (3) that embody or are made in
        accordance with any of the SKICR Patent Rights.

                1.6 TERMINATION OF PRIOR AGREEMENTS. Prostagen and NWBio entered
into a PSMA Therapeutic Product Sublicense Agreement, dated July 16, 1997 and
Prostagen and Northwest Clinical LLC entered into a PSMA Production Sublicense
Agreement, dated July 16, 1997, both of those agreements and the PSMA
Therapeutic Sublicense Agreement (as defined in Section 2) have been terminated
simultaneously with the execution of this Agreement.

        2. DEFINITIONS. For the purposes of this Agreement, the following terms,
whether used in the singular or plural, shall have the following meanings.

                2.1 AFFILIATE. The term "Affiliate" shall mean any person,
corporation, company, partnership, joint venture and/or firm which controls, is
controlled by, or is under common control with, a party. For purposes of this
definition, "control" shall mean (a) in the case of corporate entities, direct
or indirect ownership of at least fifty percent (50%) or, if less than fifty
percent (50%), the maximum percentage, as allowed by applicable law, of the
stock or participating shares entitled to vote for the election of directors;
and (b) in the case of noncorporate entities, direct or indirect ownership of at
least fifty (50%) or, if less than fifty percent (50%), the maximum percentage,
as allowed by applicable law, of the equity interest with the power to direct
the management and policies of such noncorporate entity.

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                2.2 COMMERCIAL SALE. The term "Commercial Sale" shall mean the
commercial sale of Licensed Products by NWBio.

                2.3 CONTRACT PERIOD. The term "Contract Period" shall mean the
period beginning with the Effective Date of the Agreement and ending upon the
date on which this Agreement shall expire or terminate in accordance with the
provisions of Section 8 hereof.

                2.4 EFFECTIVE DATE. The term "Effective Date of this Agreement"
shall mean July 18, 2000.

                2.5 FDA. The term "FDA" shall mean the United States Food and
Drug Administration.

                2.6 IMMUNOTHERAPY. The term "immunotherapy" shall mean and
collectively include those ex vivo therapeutic interventions which result in the
activation and/or expression of effector cell function by B lymphocytes, T
lymphocytes, NK cells, macrophages, expression of mucosal immunity, and/or
passive immunity by which immune agents are generated ex vivo and transferred to
a patient.

                2.7 IND. The term "IND" shall mean an application for
investigation of a new drug that has been submitted to the FDA pursuant to the
Federal Food Drug and Cosmetic Act, as amended [Title 21, United States Code]
and the regulations promulgated thereunder, or an equivalent application to
another Regulatory Authority.

                2.8 LICENSED PROCESSES. The term "Licensed Processes" shall mean
any process for the immunotherapy of prostate cancer in patients by * including,
but not limited to *, ex vivo, with a composition including PSMA and/or PSMP,
and/or the mimetopes of PSMA or PSMP, and * , the use or practice of which
would, but for the licenses granted herein, infringe one or more Valid Claims of
an issued patent or pending patent application included in SKICR Patent Rights.

                2.9 PSMA. The term "PSMA" shall mean prostate specific membrane
antigen and shall include the PSMA protein described in Cancer Research,
53:227-230 (1993).

                2.10 PSMP. The term "PSMP" shall mean prostate specific membrane
peptides which shall include any peptide sequence appearing within the PSMA
protein.

                2.11 LICENSED PRODUCTS. The term "Licensed Products" shall mean
products for the immunotherapy of prostate cancer which are produced by *, with
a composition including PSMA and/or PSMP, and/or the mimetopes of PSMA or PSMP,
and *, the manufacture, use and/or sale of which would, but

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

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for the licenses granted herein, infringe one or more Valid Claims of an issued
patent or pending patent application included in SKICR Patent Rights.

                2.12 MAJOR MARKET. The term "Major Market" shall mean any of the
United States, United Kingdom, France, Germany, Italy, Spain, Japan or Canada.

                2.13 MOAB 7E11. The term "MoAb 7E11 shall mean and collectively
include that certain antibody to PSMA known as MoAb 7E11-C5, which such antibody
is claimed in United States Patent No 5,162,504, granted November 10, 1992, and
entitled "Monoclonal Antibodies to a New Antigenic Marker in Epithelial
Prostatic Cells and Serum of Prostate Cancer Patients." One subclone of MoAb
7E11 is MoAb 7E11-C5.3.

                2.14 NDA. The term "NDA" shall mean either a New Drug
Application and/or a Pre-Market Approval for a Licensed Product that has been
submitted to the FDA pursuant to the Federal Food, Drug and Cosmetic Act, as
amended [Title 21, United States Code] and the regulations promulgated
thereunder or an equivalent application to another Regulatory Authority.

                2.15 PHASE III CLINICAL TRIAL. The term "Phase III Clinical
Trial" shall mean a pivotal random clinical trial having a sufficient number of
patients to provide statistically significant results regarding safety and
efficacy of a particular Licensed Product in the treatment of prostate cancer.
The Phase III Clinical Trial shall be conducted pursuant to the requirements of
the Federal Drug, Food and Cosmetic Act, as amended [Title 21, United States
Code] and regulations promulgated thereunder, and shall commence on the first
day the first patient is treated under the protocol of such Phase III Clinical
Trial.

                2.16 PSMA THERAPEUTICS SUBLICENSE AGREEMENT. The term "PSMA
Therapeutics Sublicense Agreement" shall mean the PSMA Therapeutics Sublicense
Agreement, dated December 9, 1996, by and between Cytogen and Prostagen, and all
amendments thereto.

                2.17 REGULATORY APPROVAL. The term "Regulatory Approval" shall
mean the approval of an NDA by a Regulatory Authority granting the rights to
manufacture, market and import a therapeutic agent for use by human patients.

                2.18 REGULATORY AUTHORITY. The term "Regulatory Authority" shall
mean the applicable Government authority (which, in the United States, is the
FDA) which is responsible for approval for manufacturing, marketing or importing
a therapeutic agent in a particular country for human use.

                2.19 SKICR. The term "SKICR" shall mean the Sloan-Kettering
Institute for Cancer Research, a not-for-profit New York corporation, having its
principal place of business at 1275 York Avenue, New York, New York 10021-6007.

                2.20 SKICR AGREEMENT. The "SKICR Agreement" shall mean the
Option and License Agreement effective July 1, 1993, by and between SKICR and
Cytogen, and all

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amendments thereto. The SKICR Agreement is annexed to be PSMA Therapeutics
Sublicense Agreement as Exhibit A.

                2.21 SKICR PATENT RIGHTS. The "SKICR Patent Rights" shall mean
and collectively include

                        (a) all patentable inventions specifically pertaining to
        the Technological Field (1) which are subject to protection under the
        provisions of the Patent Act [Title 35, United States Code] and/or any
        foreign patent laws; (2) which were in existence on the effective date
        of the PSMA Therapeutics Sublicense Agreement and/or which may be made
        at any time during the term of that agreement at SKICR; and (3) which
        were legally and/or beneficially owned or otherwise controlled or
        licensable by Cytogen as at its election under the SKICR Agreement.

                        (b) any and all patents and patent applications set
        forth in Schedule A of the PSMA Therapeutics Sublicense Agreement and
        any and all existing or future divisions, continuations,
        continuations-in-part and renewals thereof, any and all patents which
        may be granted thereon, and any and all reissues and extensions thereof.
        Cytogen shall promptly notify NWBio of any change in the status of any
        patent application or patent included in Schedule A of the PSMA
        Therapeutics Sublicense Agreement. Any Improvements relating to the
        Licensed Product and/or Licensed Processes shall be included in the
        SKICR Patent Rights to the extent that such Improvements have been
        licensed to Cytogen by SKICR.

                2.22 VALID CLAIM. The term "Valid Claim" with respect to any
jurisdiction shall mean any claim of any duly issued patent within the SKICR
Patent Rights in such jurisdiction that has not expired, lapsed or been declared
invalid by a decision of a court of competent jurisdiction from which an appeal
cannot be taken or in respect of which the applicable period of appeal has
expired, and any claim in any then pending application for patent within the
SKICR Patent Rights in such jurisdiction that has not been the subject of a
rejection notice from which an appeal cannot be taken or in respect of which the
applicable period of appeal has expired.

                2.23 IMPROVEMENTS. The term "Improvements" shall mean any
enhancement made by NWBio or its sublicensees to the SKICR Patent Rights.

                2.24 NET SALES. The term "Net Sales" shall mean the * from a
third party attributable to NWBio or its sublicensee's use, sale or transfer of
any Licensed Product * directly attributable to such use, sale or transfer and
actually allowed and borne by NWBio or its sublicensee. Such *

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

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* . Whenever a product is sold in the form of a combination product containing a
Licensed Product and one or more active ingredients, agents or compounds that
are proprietary, either by ownership or license, to NWBio, its Affiliates or a
third party (other than the Licensed Product), the Net Sales for such
combination product shall be calculated by * . If, on a country by country
basis, the Licensed Product and such other active ingredients, agents or
compounds in the combination product are not sole separately in such country by
NWBio or its sublicensees, Net Sales for purposes of determining royalties on
the combination product shall be calculated by * .

                2.25 TECHNOLOGICAL FIELD. The term "Technological Field" shall
mean and collectively include the NWBio Operating Field and the Excluded Field,
each of which terms is defined below:

                        2.25.1 NWBio OPERATING FIELD. The term "NWBio Operating
        Field" shall mean (a) the manufacture, production, purification or use
        of PSMA, PSMP and/or any mimetopes of PSMA or PSMP; (b) the use of the
        gene(s) encoding PSMA or PSMP solely for the manufacture or production
        of such protein or peptides; (c) the sale of PSMA, PSMP and/or mimetopes
        of PSMA or PSMP to NWBio's sublicensees; (d) the sale of PSMA, PSMP
        and/or mimetopes of PSMA or PSMP to sublicensees for ex vivo clinical
        use, and/or to others for non-clinical research purposes; and (e) the
        manufacture, production or use of Licensed Processes and/or Licensed
        Products; in each case for the immunotherapy of prostate cancer. The
        term "NWBio Operating Field" shall not include any gene therapy with
        PSMA and/or any PSMP or the use of the DNA or RNA encoding such proteins
        and/or peptides to pulse any antigen-presenting cells ex vivo.

                        2.25.2 EXCLUDED FIELD. The term "Excluded Field" shall
        mean the use of any technology and related SKICR Patent Rights for any
        purpose other than the NWBio Operating Field.

        3. REPRESENTATIONS AND WARRANTIES. The following provisions relate to
representations and warranties by the parties:

                3.1 BY CYTOGEN. Prostagen represents and warrants to NWBio that
all of the facts set forth in Article I of this Agreement are true and accurate,
and further represents and warrants, as follows:

                        3.1.1 POWER TO ACT. Cytogen has all necessary corporate
        power to enter into and perform its obligations under this Agreement and
        has taken all necessary

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

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        corporate action under the laws of the State of Delaware and its charter
        and bylaws to authorize the execution and consummation of this
        Agreement.

                        3.1.2 SKICR PATENT RIGHTS. With respect to the SKICR
        Patent Rights,

                                (a) Cytogen is the exclusive licensee under and
        has the right to grant sublicense rights under the SKICR Patent Rights
        in the Technological Field, including the right to preclude unauthorized
        use of such SKICR Patent Rights;

                                (b) that the list of patents and patent
        applications set forth in Schedule A of the PSMA Therapeutics Sublicense
        Agreement represents a full and complete list of all patents and patent
        applications (1) which are included in the SKICR Patent Rights within
        the Technological Field; and (2) which were in existence as of the
        effective date of the PSMA Therapeutics Sublicense Agreement; and

                                (c) that Cytogen had no knowledge of (1) any
        impediment to the enforceability of any patent within the SKICR Patent
        Rights; or (2) any materially relevant prior art reference(s) which has
        not been cited in the United States Patent and Trademark Office with
        respect to the prosecution of any of the United States patents or patent
        applications within such SKICR Patent Rights.

Cytogen has not made any warranty or representation to NWBio as to the
enforceability or validity of any patent within the SKICR Patent Rights.

                        3.1.3 [INTENTIONALLY BLANK]

                        3.1.4 NO LITIGATION. On the Effective Date, there is no
        action, suit, claim, proceeding or governmental investigation pending or
        threatened against Cytogen or Prostagen with respect to any of the SKICR
        Patent Rights, either at law or in equity, before any court or
        administrative agency or before any governmental department, commission,
        board, bureau, agency or instrumentality, whether United States or
        foreign, and Cytogen has no belief that there are basis or grounds for
        any such actions, suits or claims.

                        3.1.5 NO DEFAULT. On the Effective Date, Cytogen is not
        in default with respect to any term or provision of any agreement,
        charter, bylaw, mortgage, indenture, statute, rule or regulation
        applicable to either of them or with respect to any order, writ,
        injunction, decree, rule or regulation of any court or administrative
        agency, which will preclude the performance of its obligations under
        this Agreement.

                        3.1.6 NO MATERIAL CONTRACTS. Cytogen is not subject to
        any contract or agreement materially affecting any of the SKICR Patent
        Rights which will preclude the performance of Cytogen's obligations
        under this Agreement.

                        3.1.7 NO CONFLICTS. Neither the execution nor delivery
        of this Agreement, nor the consummation of the transactions herein
        contemplated, nor the

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        fulfillment of or compliance with the terms and provisions hereof will
        (a) violate any provisions of law, administrative regulation or court
        decree applicable to Cytogen; or (b) conflict with or result in a breach
        of any of the terms, conditions or provisions of or constitute a default
        under the certificate of incorporation or bylaws of Cytogen, or of any
        agreement or instrument to which Cytogen is a party or by which Cytogen
        is bound.

                        3.1.8 NO ADVERSE ACTIVITY. During the term of this
        Agreement, Cytogen shall engage in no activity or omission that would
        adversely affect the rights of NWBio under this Agreement.

                3.2 BY NWBio. NWBio represents and warrants to Cytogen, as
follows:

                        3.2.1 POWER TO ACT. NWBio has all necessary power to
        enter into and perform its obligations under this Agreement and has
        taken all necessary action under the laws of the State of Washington and
        its articles of incorporation and bylaws to authorize the execution and
        consummation of this Agreement.

                        3.2.2 NO DEFAULT. NWBio is not in default with respect
        to any term or provision of any agreement, charter, bylaw, mortgage,
        indenture, statute, rule or regulation applicable to it, or with respect
        to any order writ, injunction, decree, rule or regulation of any court
        or administrative agency, which will preclude the performance of its
        obligations under this Agreement.

                        3.2.3 NO MATERIAL CONTRACTS. NWBio is not subject to any
        contract or agreement which will preclude the performance of NWBio
        obligations under this Agreement.

                        3.2.4 NO CONFLICTS. Neither the execution nor delivery
        of this Agreement, nor the consummation of the transactions herein
        contemplated nor the fulfillment of or compliance with the terms and
        provisions hereof will (a) violate any provisions of law, administrative
        regulation or court decree applicable to NWBio; or (b) conflict with or
        result in a breach of any of the terms, conditions or provisions of or
        constitute a default under the articles of incorporation or bylaws of
        NWBio, or of any agreement or instrument to which NWBio is a party or by
        which it is bound.

        4. LICENSES. The following provisions relate to the rights and licenses
granted hereunder:

                4.1 GRANT BY CYTOGEN. Subject to the terms and conditions herein
contained, Cytogen hereby grants to NWBio the exclusive right and sublicense
throughout the world only in the NWBio Operating Field, with the right to grant
sublicenses to others,

                        (a) to make, have made, distribute, import, export, use
        and sell, and sell Licensed Products, and

                        (b) to practice and use Licensed Processes

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        embodying or made in accordance with the appropriate SKICR Patent
        Rights.

Nothing contained herein shall be construed as granting NWBio any right or
license to practice the SKICR Patent Rights within the Excluded Field or for any
purpose other than within the NWBio Operating Field.

                4.2 LIMITED RIGHT TO MOAB 7E11-C5.3. To enable NWBio to utilize
MoAb 7E11-C 5.3 in connection with the development, manufacturing, testing, or
conducting quality control tests on Licensed Products and to practice Licensed
Processes all in accordance with Section 4.1, Cytogen hereby grants NWBio the
right to use MoAb 7E11-C.5.3 solely for such purposes.

                        4.2.1 ANTIBODY REQUIREMENTS. NWBio agrees to purchase
        its requirements of MoAb 7E11-C5.3 from Cytogen, and Cytogen agrees to
        supply NWBio requirements of MoAb 7E11-C5.3, on terms and conditions
        satisfactory to both Cytogen and NWBio.

                        4.2.2 CONTINGENT LICENSE. In the event that Cytogen is
        unable or unwilling to supply NWBio requirements of MoAb 7E11-C5.3,
        Cytogen shall, upon written request of NWBio, provide to NWBio, at no
        cost to NWBio, a viable sample of a hybridoma capable of producing MoAb
        7E11-C5.3, and thereafter NWBio shall have the right to use the
        hybridoma and to produce and use MoAb 7E11-C5.3 for the purposes set
        forth in this Paragraph 4.2.

        5. DILIGENCE. NWBio shall use reasonable commercial efforts to promptly
develop, obtain Regulatory Approval for, manufacturing, marketing and selling
Licensed Products. In the event that Cytogen, from time to time during the term
of this Agreement, determines, in the exercise of its reasonable business
discretion after interaction and discussion with NWBio, that NWBio is not using
reasonable commercial efforts to develop, obtain Regulatory Approval for,
manufacturing, marketing and selling Licensed Products within the United States
and at least one other Major Market, then the resolution of such matter will be
finally settled by binding arbitration in Seattle, Washington in accordance with
the then current rules and procedures of the American Arbitration Association,
by one (1) arbitrator appointed in accordance with such rules. The arbitrators
shall apply the laws of the State of Washington, without reference to rules of
conflict of law or statutory rules of arbitration, to the merits of any dispute
or claim and shall have the right to grant injunctive relief. Judgment on the
award rendered by the arbitrators may be entered in any Court having
jurisdiction thereof.

        6. MILESTONE PAYMENTS AND ROYALTIES. The following provisions relate to
milestone and royalty payments to be made by NWBio hereunder:

                6.1 MILESTONE PAYMENTS. The following provisions relate to the
milestone payments to be made by NWBio hereunder:

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                        6.1.1 FIRST MILESTONE PAYMENT. Within thirty (30) days
        of the issuance of the first Regulatory Approval for the use of a
        Licensed Product in a Major Market, other than for PSMA and/or PSMP,
        NWBio shall pay Cytogen the sum of * .

                        6.1.2 FINAL MILESTONE PAYMENT. NWBio shall pay Cytogen
        the sum of * ; which amount shall be payable in installments in
        accordance with Subsections 6.5.2 and 6.5.3, each of which shall be
        equal to two percent (2%) of the Net Sales for the immediately preceding
        calendar quarter. Such installments shall commence on the last day of
        the month during which the first Commercial Sale transpires and continue
        until the earlier of (i) two (2) years or (ii) the aggregate amount of
        such payments * . In the event that that aggregate amount of the such
        payments is less than * then the amount of the final payment shall be
        increased so that the aggregate amount of all payments made pursuant to
        this Subsection 6.1.2 is equal to * . Notwithstanding anything to the
        contrary in this Agreement, in no event shall the * sum be fully paid by
        NWBio to Cytogen later than two (2) years from the first payment
        specified above in this Subsection 6.1.2.

                6.2 MINIMUM ANNUAL PAYMENTS. During each twelve (12) month
        period of the Agreement commencing on the Effective Date, until the
        commencement of the Phase III Clinical Trial (including pro-rata the
        last 12 month period), NWBio agrees to pay Cytogen minimum annual
        payments of * per year.

                6.3 ROYALTY PAYMENTS. NWBio shall, during the Contract Period,
pay Cytogen a royalty of * on all Net Sales. Such payments will be paid in
accordance with Subsections 6.5.2 and 6.5.3 below.

                6.4 BOOKS AND RECORDS. NWBio agrees to keep adequate and
complete records showing all Net Sales, with respect to which earned royalties
are due Cytogen hereunder. Such records shall include all information necessary
to verify the total amount and computation of earned royalties hereunder, and
shall be open to inspection by Cytogen during reasonable business hours to the
extent necessary to verify the amount thereof. Such inspection shall be made no
more often than once each calendar year at the expense of Cytogen by an auditor
appointed by Cytogen and to whom NWBio has no reasonable objection, provided
that such auditor shall be under a confidentiality obligation to NWBio to reveal
only that information, and only to Cytogen, necessary to verify the royalties
due hereunder. In addition, such inspection shall be limited to a period not to
extend beyond two (2) years after the date of the receipt by Cytogen of a report
from NWBio relating to such records pursuant to Section 6.5.1. After such two
(2) year period, any such report and the records upon which such report was
based shall be deemed presumptively correct.

                6.5 REPORTS AND ROYALTY PAYMENTS. The following provisions
relate to reports and royalty payments by NWBio:

                        6.5.1 REPORTS. On or before the last day of each
        February, May, August, and November throughout the Contract Period,
        NWBio shall furnish Cytogen

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       10
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        with a written report, signed by an authorized officer or agent of NWBio
        showing all Net Sales with respect to which earned royalties are due
        Cytogen hereunder.

                        6.5.2 ROYALTY PAYMENTS. With each such quarterly report,
        NWBio shall remit to Cytogen the total amount of earned royalties shown
        thereby to be due. All payments shall be made in lawful funds of the
        United States of America.

                        6.5.3 CURRENCY CONTROL RESTRICTIONS. In the event that
        NWBio is precluded from transferring royalties due Cytogen hereunder at
        any time during the Contract Period because NWBio has failed after due
        diligence to obtain the approval of such transfer from the appropriate
        governmental agency responsible for control of currency exchanges of a
        particular country in which NWBio has sold Licensed Products, then NWBio
        agrees (a) to deposit or to cause the deposit of such royalties to the
        account of Cytogen in a bank in such country designated by Cytogen; (b)
        to provide or to cause the providing of Cytogen with documentary
        evidence of such deposits; and (c) to remit or to cause remittance of
        such deposits to Cytogen immediately upon the subsequent approval of
        such transfers by such governmental agency. NWBio further agrees that
        the form of such depository account shall permit Cytogen to withdraw the
        deposited amounts at will, but shall permit NWBio to withdraw the
        deposited amounts solely for the purpose of remitting such amounts to
        Cytogen pursuant to the provisions of this Section 6.5.3.

        7. PRODUCT LIABILITY DISCLAIMERS. The following provisions relate to
product liability disclaimers:

                7.1 PRODUCT LIABILITY DISCLAIMER BY CYTOGEN. Cytogen assumes no
responsibility for the manufacturer, product specifications, end-use or
provision of any Licensed Products which are manufactured or provided by or for,
or sold by NWBio. All warranties in connection with such Licensed Products made
or provided by NWBio shall not directly or impliedly obligate Cytogen in any
manner whatsoever under such warranties or otherwise.

                7.2 PRODUCT LIABILITY DISCLAIMER BY NWBio. NWBio assumes no
responsibility for the manufacture or product specifications or end-use of any
products which are manufactured by or for Cytogen except for the manufacture or
product specifications of materials made by or for NWBio and sold to Cytogen.
Any warranties in connection with such products made by Cytogen as user of such
products shall nor directly or impliedly obligate NWBio.

        8. TERM AND TERMINATION. The following provisions relate to the term and
termination of this Agreement:

                8.1 TERM. Unless sooner terminated in a manner herein provided,
this Agreement shall continue in force until the expiration of the last to
expire patent included in SKICR Patent Rights.

                8.2 TERMINATION. This Agreement may be terminated, in whole or
in part, at any time prior to the term set forth in Paragraph 8.1 hereof, as
follows:

                                       11
<PAGE>   13

                        8.2.1 BY NWBio. At any time after December 31, 2000,
        NWBio may terminate this Agreement by giving Cytogen at least sixty (60)
        days notice in writing.

                        8.2.2 BY BREACH. In the event either party shall
        materially breach any of the terms, conditions or agreements contained
        herein to be kept, observed and performed by it, then the other party
        may give written notice thereof to the breaching party. If the breaching
        party has not cured the breach within sixty (60) days after receipt of
        such notice, then the non-breaching party may commence arbitration of
        such matter pursuant to the arbitration provisions set forth in Section
        5 above.

                        8.2.3 BY BANKRUPTCY, INSOLVENCY OR SUSPENSION OF
        BUSINESS. In the event (a) NWBio on the one hand or Cytogen on the other
        hand shall become insolvent or shall suspend business, or shall file a
        voluntary petition or any answer admitting the jurisdiction of the Court
        and the material allegations of, or shall consent to an involuntary
        petition pursuant to or purporting to be pursuant to any reorganization
        or insolvency law of any jurisdiction, or shall make an assignment for
        the benefit of creditors, or shall apply for or consent to the
        appointment of a receiver or trustee of a substantial part of its
        property, and (b) no Affiliate of such party shall undertake to assume
        its obligations under the provisions of this Agreement within ninety
        (90) days from the date on which such party becomes so disabled, then to
        the extent permitted by law the other party may thereafter immediately
        terminate this Agreement by giving written notice of termination to the
        disabled party.

                8.3 ACCRUED RIGHTS AND OBLIGATIONS. Termination of this
Agreement shall not relieve any party of any rights and obligations then accrued
hereunder or which extend beyond the date of such termination. In the event that
this Agreement is terminated pursuant to Sections 8.2.2 or 8.2.3 due to the
breach, bankruptcy, insolvency or business suspension of Cytogen, NWBio shall
have the right to use the licenses granted under this Agreement until the last
to expire patent included in SKICR Patent Rights; provided, however, NWBio shall
adhere to all terms and conditions, including making any payments specified
herein. If the Agreement is terminated by Cytogen pursuant to the terms of this
Agreement, all licenses granted to NWBio shall immediately cease and NWBio will
return any and all Cytogen materials. NWBio shall have the right to sell-off any
inventory of Licensed Products manufactured prior to the termination date, under
the terms and conditions specified in this Agreement.

        9. ASSIGNABILITY. Neither this Agreement nor any interest hereunder
shall be assignable by either party without the written consent of the other,
and any attempted assignment without such consent shall be null and void. For
the purposes of this Section 9, a change of corporate domicile by either party
hereof shall not result in an assignment of this Agreement or any interest
hereunder. This Agreement shall be binding upon the successors and permitted
assignees of the parties. Any such successor or permitted assignee shall be
subject to the same rights and obligations as the original party hereunder.

        10. EXPORT LICENSES. This Agreement is subject to any restrictions
concerning the export of products or technical information from the United
States which may be imposed by the

                                       12
<PAGE>   14

United States. Accordingly, each party agrees that it will not export directly
or indirectly, any technical information acquired under this Agreement or any
products utilizing any such technical information to any country for which the
United States Government or any agency thereof at the time of export requires an
export license or other governmental approval, without first obtaining the
written consent to do so from the Department of Commerce or other agency of the
United States Government when required by an applicable statute or regulation.

        11. MISCELLANEOUS PROVISIONS. The following miscellaneous provisions
shall apply to this Agreement:

                11.1 NOTICES. All notices and communications provided for
hereunder shall be in writing and shall be mailed or delivered to the business
address of the respective parties aforementioned, or to such other address as
either party shall designate in writing to the others.

                11.2 INDEPENDENT CONTRACTORS. No agency, partnership or joint
venture is hereby established. Neither Cytogen nor NWBio shall enter into, or
incur, or hold itself out to third parties as having authority to enter into or
incur on behalf of the other party any contractual obligations, expenses or
liabilities whatsoever, except as expressly provided herein.

                11.3 COUNTERPARTS. This Agreement may be executed simultaneously
in multiple counterparts, each of which shall be deemed to be an original but
all of which together shall constitute one and the same agreement.

                11.4 ENTIRE UNDERSTANDING. This Agreement constitutes the entire
understanding between the parties hereto with respect to the subject matter
hereof. No modifications, extensions, or waiver of any provisions hereof or any
release of any right hereunder shall be valid, unless the same is in writing,
contains reference to this Agreement and sets forth the plan or intention to
modify same, and is consented to by all parties hereto.

                11.5 HEADINGS. The headings of this Agreement are intended
solely for convenience of reference and shall be given no effect in the
construction or interpretation of this Agreement.

                11.6 NO IMPLIED RIGHTS. Except as expressly provided for in this
Agreement, nothing contained herein shall be construed as conferring any license
or other rights, by implication or estoppel, under any patent (including design
patent and utility model patent) or patent application, or any copyrights,
trademarks, trade names or trade dress.

                11.7 NO WAIVER. The failure of either party hereto at any time
or times to require performance of any provision hereof shall in no manner
affect the right of such party at a later time to enforce the same. No waiver by
any party hereto of any condition, or of the breach of any provision, term,
covenant, representation, or warranty contained in this Agreement, whether by
conduct or otherwise, in any one or more instances, shall be deemed to be or
construed as a further or continuing waiver of any such condition or of the
breach of any other provision, term, covenant, representation, or warranty of
this Agreement.

                                       13
<PAGE>   15

                11.8 PROMOTION AND ADVERTISING. Nothing contained in this
Agreement shall be construed as conferring any right to use in advertising,
publicity or other promotional activities any name, trade name, trademark, or
other designation (including any contraction, abbreviation, or simulation of any
of the foregoing); and, each party hereto agrees not to use any designation of
the other party in any promotional activity associated with this Agreement, or
with product licensed thereunder, without the express written approval of the
other party.

                11.9 GOVERNING LAW. This Agreement shall be interpreted,
construed, and governed in accordance with the laws of the State of Washington,
without reference to conflict of laws principles.

        IN WITNESS WHEREOF, the parties have each caused their respective
corporate seals to be hereto affixed and duly witnessed and these present to be
signed by their respective corporate officers thereunto duly authorized.

CYTOGEN CORPORATION                         NORTHWEST BIOTHERAPEUTICS INC.

By                                          By
  ---------------------------------            ---------------------------------

Title                                       Title
     ------------------------------               ------------------------------

Date:  August 28, 2000                      Date:  August 28, 2000

                                       14<PAGE>   1

                                                                    EXHIBIT 10.2

                            COLLABORATION AGREEMENT

        THIS COLLABORATION AGREEMENT ("AGREEMENT") is made and entered into
effective as of April 24, 2001 (the "EFFECTIVE DATE"), by and between NORTHWEST
BIOTHERAPEUTICS, INC., having principal offices at 21270 23rd Dr. SE, Suite 100,
Bothell, Washington 98021 ("NORTHWEST") and MEDAREX, INC., having principal
offices at 707 State Road, Suite 206, Princeton, New Jersey 08540-1437, on
behalf of itself and its wholly owned subsidiary, GENPHARM INTERNATIONAL, INC.,
with principal offices at 2350 Qume Drive, San Jose, California 95131
(collectively, "MEDAREX"). Northwest and Medarex each may be referred to herein
individually as a "PARTY," or collectively as the "PARTIES."

        WHEREAS, Medarex and Northwest desire to enter into a definitive
agreement to collaborate to produce fully human monoclonal antibodies to certain
antigen targets in order to develop and commercialize genomics-derived,
antibody-based products on the terms set forth below;

        NOW, THEREFORE, in consideration of the foregoing premises and the
mutual promises and covenants contained herein and other good and valuable
consideration, the receipt and sufficiency of which are hereby acknowledged, the
Parties, intending to be legally bound, do hereby agree as follows:

                                    ARTICLE 1
                SCOPE OF COLLABORATION; COLLABORATION ACTIVITIES

        SECTION 1.1 SCOPE OF COLLABORATION. The Parties have entered into this
collaboration (such collective enterprise, the "COLLABORATION") to jointly
research, develop and commercialize Collaboration Products with respect to
Collaboration Targets throughout the Territory as set forth in this Agreement.
Any capitalized term used in this Agreement not otherwise defined herein shall
have the meaning set forth on Appendix A.

        SECTION 1.2 RESEARCH ACTIVITIES.

                1.2.1 GENERAL. Under the direction and supervision of the
Steering Committee, the Parties shall use Commercially Reasonable Efforts to
conduct their respective research activities in accordance with this Agreement,
each Project Plan and each Project Budget.

                1.2.2 VALIDATION OF COLLABORATION TARGETS. Northwest shall
provide to the Collaboration those Antigens set forth on Appendix C-1 hereto
(each such Antigen shall be an "INITIAL ANTIGEN" until accepted by Medarex
pursuant to the terms of this subsection 1.2.2, at which time such Initial
Antigen shall be deemed a "COLLABORATION TARGET" for all purposes of this
Agreement and added to Appendix C-2, which Appendix C-2 may be amended pursuant
to this subsection 1.2.2 and Sections 1.7 or 5.1.2 or by the "press written
agreement of Medarex and Northwest). In addition, during each of the four (4)
years of the Target Entry Period, Northwest shall propose to Medarex additional
Antigens (each, a "SUBSEQUENT Antigen") for evaluation by Medarex as provided in
this subsection 1.2.2, until such time as Medarex has accepted one (1)

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.
<PAGE>   2

additional Subsequent Antigen as a Collaboration Target (in addition to the
Initial Antigens and any replacements thereto pursuant to subsection (d) below)
for each such year. For each Initial Antigen or Subsequent Antigen proposed by
Northwest pursuant to this Agreement, Medarex may decline such target in its
sole discretion if Medarex (i) is researching or developing, or has researched
and developed, in collaboration with a Third Party, antibodies to such Initial
Antigen or Subsequent Antigen (either alone or as part of a joint development
program with a Third Party) or (ii) has previously granted to a Third Party
exclusive rights with respect to such Initial Antigen or Subsequent Antigen or
with respect to antibodies to such Initial Antigen or Subsequent Antigen.

                        (a) ANTIGEN EVALUATION MATERIALS. With respect to each
Initial Antigen and each Subsequent Antigen, Northwest shall promptly develop
and furnish to Medarex the following data and information ("ANTIGEN EVALUATION
MATERIALS"):

                                (i) a written description of the applicable
Antigen, including * thereof, when available;

                                (ii) the * and/or * for such Antigen,

                                (iii) * that Northwest believes in good faith to
be reasonably necessary for determining whether such * ;

                                (iv) * data in the possession of Northwest
or its Affiliates relating to such Antigen and relevant to the Collaboration-,

                                (v) all information regarding the * of such
Antigen, the * by Northwest and its Affiliates with respect to such Antigen, and
any * or otherwise) that would * the Parties' right to fully Exploit any
Collaboration Products with respect thereto;

                                (vi) existing and available * for *;

                                (vii) a list of * for Antibody Products against
such Antigen-,

                                (viii) * applicable to Antibody Products against
such Antigen, to the extent known by Northwest;

                                (ix) any * undertaken by or on behalf of
Northwest or its Affiliates with respect to the * against such Antigen;

    As Filed with the Securities and Exchange Commission on August 10, 2001.
* INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       2
<PAGE>   3
                                (x) the * for * for the development of
antibody-based products; and

                                (xi) * in Northwest's or its Affiliates'
possession with respect to * .

                        (b) ADDITIONAL VALIDATION ACTIVITIES. In the event
Medarex receives Antigen Evaluation Materials for a given Initial Antigen or
Subsequent Antigen pursuant to Section 1.2.2(a), but does not believe such
materials are sufficiently complete, the Parties shall discuss in good faith
additional analyses to be performed by Northwest in order to complete the
Antigen Evaluation Materials and Northwest shall use Commercially Reasonable
Efforts to perform such additional analyses to the reasonable satisfaction of
Medarex.

                        (c) EVALUATION OF COLLABORATION TARGETS.

                                (i) Upon receipt of the Antigen Evaluation
Materials pursuant to subsection (a) above and any additional materials pursuant
to subsection (b) above, Medarex shall evaluate the scientific merits of the
respective Initial Antigen or Subsequent Antigen. If such evaluation reveals in
the reasonable opinion of Medarex that such Initial Antigen or Subsequent
Antigen is not sufficiently characterized or validated so as to permit a
successful development of Collaboration Products under this Agreement, the
Parties shall meet to discuss Medarex's concerns. If such concerns remain
unresolved after such meeting, such Initial Antigen or Subsequent Antigen shall
not become a Collaboration Target, excluded from the Collaboration and returned
to Northwest, and Medarex shall have no further rights to such Initial Antigen
or Subsequent Antigen under this Agreement.

                                (ii) Upon request of either Party, the Steering
Committee shall solicit a formal patent review and opinion regarding each
Collaboration Target prior to the commencement of any development activities
with respect to such target. Such review shall be performed by an outside law
firm selected by the Steering Committee. The costs of such formal opinion shall
be * . If such review reveals that it is more likely than not that Collaboration
Products developed against such Collaboration Target will be subject to claims
of infringement of Patents owned by Third Parties, the Parties shall meet to
discuss how to further proceed. If the Parties agree not to proceed with the
identification and development of Collaboration Antibodies against such target,
or if the Parties are unable to agree on whether or not to proceed, such
Collaboration Target shall be excluded from the Collaboration and returned to
Northwest, and Medarex shall have no further rights to such Antigen under this
Agreement.

                        (d) REPLACEMENT OF INITIAL ANTIGENS. For each Initial
Antigen and Subsequent Antigen that is excluded from the Collaboration and
returned to Northwest as provided in subsection (c)(i) above and for each
Collaboration Target that is excluded from the Collaboration pursuant to Section
(c)(ii) above, Northwest shall use Commercially Reasonable Efforts to propose to
Medarex within ninety (90) days from the date thereof ("Replacement Period")
another Initial Antigen or Subsequent Antigen for inclusion in this Agreement as
a Collaboration Target, and the Parties shall proceed with the evaluation of
such Initial Antigen or

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       3
<PAGE>   4

Subsequent Antigen as provided in Section 1.2.2 above. Northwest's obligation to
provide new Antigens for evaluation by Medarex shall expire upon the expiration
of the Target Entry Period and the Replacement Period with respect to the last
Initial Antigen or Subsequent Antigen that has been returned to Northwest as
provided above.

                        (e) ADDITIONAL COLLABORATION TARGETS. Northwest shall
have the right to offer additional Antigens to the Collaboration as
Collaboration Targets, by providing Medarex with any and all Antigen Evaluation
Materials with respect to such Antigen and such other information and data as
Medarex may request. In the event that the Parties agree to accept any such
additional Antigen into the Collaboration, the Parties shall use good faith
efforts to agree on a written description of such Antigen, and Appendix C-2
shall be automatically amended to include such Antigen and such description.

                        (f) Upon completion of the evaluation pursuant to this
Section 1.2.2 and acceptance of a Collaboration Target by Medarex, the Parties
shall proceed with the Collaboration with respect to such target as provided in
Section 1.2.3 et seq. below.

                1.2.3 IDENTIFICATION OF APPLICABLE ASSAYS AND SUCCESS CRITERIA.
As part of the Project Plan for a given Collaboration Target, the Steering
Committee will:

                        (a) identify the immunogen(s) (each, an "IMMUNOGEN") to
be used to enable Medarex to perform its activities pursuant to Section 1.2.5;

                        (b) determine which Party will be responsible for
delivering the Immunogen(s) to Medarex.

                        (c) identify a set of assays (each, an "ASSAY") for
screening Assay Candidates against such Collaboration Target;

                        (d) determine which Party will be responsible for
delivering the Assays to the Collaboration; and

                        (e) establish criteria (the "ASSAY SUCCESS CRITERIA")
for determining, subject to Section 1.2.6, whether an Assay Candidate should
become a Collaboration Antibody; and

                        (f) update the description of Collaboration Target and
the potential utility of Antibody Products thereto in Appendix C to more
accurately reflect what Antigens, or portions thereof, are included in the
Collaboration as such additional information becomes available in the course of
the Collaboration.

The Steering Committee may elect to use a Third Party to provide one or more
Immunogen(s) to the Collaboration. In addition, the Steering Committee may elect
to have a Third Party develop and/or perform one or more of the Assays.

                                       4
<PAGE>   5
                1.2.4 ALLOCATION OF COSTS. All costs associated with identifying
Collaboration Targets, preparing and furnishing to Medarex complete Antigen
Evaluation Materials with respect thereto, and creating and delivering the
Immunogen(s) to Medarex (the "NORTHWEST RESEARCH ACTIVITIES") shall be borne
100% by Northwest. All costs associated with immunizing the HuMAb Mice and
raising a panel of different Antibodies to the applicable Collaboration Target
pursuant to the last sentence of Section 1.2.5 (the "MEDAREX RESEARCH
ACTIVITIES") shall be borne * . All costs associated with developing and
performing the Assays shall be borne * . The Parties acknowledge and agree that
the Northwest Research Activities and the Medarex Research Activities are deemed
to be and are of equal value and neither Party shall have any right to
reimbursement or credit from the other Party for the cost and expenses
associated with such research activities.

                1.2.5 RAISING OF ANTIBODIES BY MEDAREX. The Party designated
under Section 1.2.3(b) shall provide to Medarex sufficient Immunogen for each
Collaboration Target to enable Medarex to perform its activities pursuant to
this Section 1.2.5. Upon the delivery of such Immunogen, Medarex shall use
Commercially Reasonable Efforts to immunize the HuMAb Mice and raise a panel of
different Antibodies to the applicable Collaboration Target.

                1.2.6 SELECTION OF ASSAY CANDIDATES; ASSAY SCREENING; SELECTION
OF COLLABORATION ANTIBODIES.

                        (a) Medarex shall select a subset of the Antibodies
raised pursuant to Section 1.2.5 to become "ASSAY CANDIDATES" by identifying
those of the Antibodies that have a greater likelihood to qualify as
Collaboration Antibodies. Medarex will make available to the Steering Committee
such raw data and information as may be requested from time to time regarding
the Antibodies raised pursuant to Section 1.2.5 and the selection criteria
applied by Medarex. Subject to Section 1.2.6(b), upon review of the data
presented by Medarex, the Steering Committee shall have the right to designate
additional Antibodies as Assay Candidates. As set forth under the applicable
Project Plan, the Parties shall run each Assay Candidate through the applicable
Assays. Upon completion of the Assay screening for a given Assay Candidate, each
Party will be provided with the results of such screening (including the raw
data underlying such results). The Steering Committee will then determine
whether the Assay Candidate has met the applicable Assay Success Criteria.
Subject to Section 1.2.6(b), each Assay Candidate that meets the applicable
Assay Success Criteria shall be deemed to be a "COLLABORATION ANTIBODY";
provided, however the Steering Committee may, in its sole discretion, (i) decide
that an Assay Candidate that meets the Assay Success Criteria shall nonetheless
not be deemed to be a Collaboration Antibody, or (ii) decide that an Assay
Candidate that does not meet the Assay Success Criteria shall nonetheless be
deemed to be a Collaboration Antibody.

                        (b) Promptly after the identification of any Assay
Candidate that meets the Assay Success Criteria, Medarex shall determine whether
Medarex: (i) is researching or developing, or has researched or developed,
either alone or in collaboration with a Third Party, such Assay Candidate, or
(ii) has previously granted a Third Party rights with respect to such Assay
Candidate (each a "Reserved Antibody"). Medarex shall inform Northwest without
delay of its determination, and any Assay Candidates that are Reserved
Antibodies shall not become Collaboration Antibodies, and all amounts of such
Reserved Antibodies produced pursuant to

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       5
<PAGE>   6

this Agreement %rill be destroyed. If an Assay Candidate is precluded from
becoming a Collaboration Antibody under this Section 1.2.6(b), then
notwithstanding Section 1.2.4 and anything herein to the contrary, Medarex:
shall bear one hundred percent (100%) of all cost associated with developing and
performing Assays with respect to such Assay Candidate (i.e. pro rated over all
Antibodies for which such Assay was developed and performed).

                1.2.7 EFFECT OF DESIGNATION OF COLLABORATION ANTIBODIES. Any
Antibody that is designated a Collaboration Antibody in accordance with Section
1.2.6 shall be exclusive to the Collaboration. Except as otherwise provided in
this Agreement, once an Antibody is designated a Collaboration Antibody, * as
more fully described in Section 4. 1.

                1.2.8 LEAD COLLABORATION ANTIBODIES. Out of the pool of
Collaboration Antibodies against a given Collaboration Target, the Steering
Committee will select the Collaboration Antibody that it believes to be most
promising for development and commercialization and it will then move such
Collaboration Antibody into Production Process Development. Each Collaboration
Antibody that is put into Production Process Development shall be deemed to be a
"LEAD COLLABORATION ANTIBODY." It is understood that the Steering Committee may,
over time, select more than one Lead Collaboration Antibody against a given
Collaboration Target, or substitute one Lead Collaboration Antibody for another.
Upon designation of each Lead Collaboration Antibody, the Parties shall commence
Production Process Development for such antibody. * of Production Process
Development as provided in Section 1.2.7 above; provided that if the Steering
Committee elects to have Medarex perform such Production Process Development,
then such fifty percent (50%) share of Production Process Development costs
shall be calculated based on Medarex's Fully-Burdened Production Process
Development Cost.

        SECTION 1.3 PROJECT PLAN AND PROJECT BUDGET. Upon designation of a given
Antigen as a Collaboration Target pursuant to Section 1.2.2, Medarex and
Northwest under the direction of the Steering Committee shall jointly develop
and implement a Project Plan (each a "PROJECT PLAN") and Project Budget (each a
"PROJECT BUDGET") for the research, development, manufacture and
commercialization of Collaboration Antibodies against such Collaboration Target.
It is understood that the components of each Project Plan and Project Budget
will evolve as the applicable Collaboration Antibodies move through the
research, development, manufacture and commercialization life cycle.

        SECTION 1.4 PERFORMANCE STANDARDS. Each Party shall perform, or cause to
be performed, its respective activities hereunder in good scientific manner, and
in compliance in all material respects with all Applicable Law and shall use
Commercially Reasonable Efforts to (a) research, develop, file for Regulatory
Approval and commercialize one or more Collaboration Products with respect to
each Lead Collaboration Antibody, and (b) achieve the objectives of each Project
Plan in accordance with each Project Budget, in each case, efficiently and
expeditiously by allocating sufficient time, effort, equipment and skilled
personnel to complete such activities successfully and promptly.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       6
<PAGE>   7
        SECTION 1.5 PRODUCT TRADEMARKS. The Parties shall develop Product
Trademarks for each Collaboration Product that will be commercialized. Such
Product Trademarks shall not be confusingly similar to, misleading or deceptive
with respect to, or dilute any of the Trademarks owned or Controlled by either
of the Parties, or any part of such Trademarks. No Party or any of its
Affiliates or sublicensees shall commercialize a Collaboration Product under any
Trademark other than the Product Trademarks. No Party or any of its Affiliates
or sublicensees shall use in its business any Trademark that is confusingly
similar to, misleading or deceptive with respect to, or dilutes any of the
Product Trademarks or any other Trademarks used to identify or distinguish a
Collaboration Product, or any part of the foregoing. The Steering Committee
shall oversee the filing, prosecution and maintenance of all Product Trademark
registrations. The * of such filing, prosecution and maintenance. Subject to
Applicable Law, the label of any Collaboration Products shall include, at
Northwest's sole discretion, the name of Northwest and, at Medarex's sole
discretion, the name of Medarex.

        SECTION 1.6 SUPPLY OF COLLABORATION PRODUCTS. Each Party shall have the
right to submit to the Steering Committee a proposal for the manufacture of
clinical and/or commercial supplies of Collaboration Products. The Steering
Committee shall negotiate at arm's length with each Party that submits such
proposal the price and other terms and conditions of such supply, and, subject
to the terms of this Section 1.6, shall select one of the Parties as the
manufacturer of Collaboration Products after such arm's length negotiations;
provided that the terms arrived at in such negotiations shall be competitive
compared to other manufacturers of antibody products in the industry. In the
event that the Steering Committee determines that the terms offered by either or
both Parties at the end of such negotiations are not competitive, the Steering
Committee shall solicit bids from Third Party suppliers to supply the Parties'
requirements thereof In any event, the Steering Committee shall use its best
efforts to enter into a supply agreement with the supplier that is best able to
meet the Parties' requirements, taking into consideration such factors as price,
quality, capacity, quantity, reliability, timeliness and reputation.

        SECTION 1.7 REVERSION OF COLLABORATION TARGETS. If, notwithstanding the
Commercially Reasonable Efforts of the Parties, no Collaboration Antibodies have
been designated with respect to a Collaboration Target pursuant to Section
1.2.6(a) within two (2) years, or such other period as the Parties may agree,
after the immunization of the HuMAb Mice with respect to such Collaboration
Target pursuant to Section 1.2.5, then (a) such Antigen shall cease to be a
Collaboration Target (such Antigen, a "REVERSION TARGET"), and Appendix C shall
be amended accordingly, (b) any Antibodies with respect thereto shall not become
Collaboration Antibodies, (c) any Antibody Products with respect thereto shall
not become Collaboration Products, and (d) any licenses granted pursuant to
Article 3, with respect to such Antigen, Antibody or Antibody Product shall
terminate. Promptly upon such designation, the Parties shall destroy all
Antibody Products and other Biological Materials created under this Agreement
with respect to such a Reversion Target.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       7
<PAGE>   8

                                    ARTICLE 2
                         OPERATION OF THE COLLABORATION

        SECTION 2.1 STEERING COMMITTEE.

                2.1.1 FORMATION OF STEERING COMMITTEE. The Parties shall
establish a joint committee (the "STEERING COMMITTEE"), which shall oversee the
research, development and commercialization activities hereunder. Each of
Northwest and Medarex: shall appoint an equal number of representatives with the
requisite experience and seniority to enable them to make decisions on behalf of
the Parties with respect to the Collaboration. From time to time, Northwest and
Medarex each may substitute any of its representatives to the Steering
Committee.

                2.1.2 RESPONSIBILITIES. The Steering Committee shall, in
addition to its other responsibilities described in this Agreement: (a)
prioritize the research, development, manufacturing and commercialization
activities with respect to Collaboration Targets, Collaboration Antibodies and
Collaboration Products; (b) subject to Section 1.3, allocate responsibility for
such activities between Northwest and Medarex taking into consideration their
relevant expertise and available resources; (c) develop and implement a strategy
for researching, developing, manufacturing, obtaining and maintaining Regulatory
Approvals for, and commercializing, the Collaboration Products; (d) establish
such subcommittees as deemed appropriate by the Steering Committee; and (e) take
such other actions as are set forth in this Article 2 or as the Parties may
unanimously agree. The Steering Committee may evaluate additional technologies
that may be necessary or beneficial to the Collaboration and may recommend the
acquisition or in-licensing of these technologies to the Parties. Except for its
ability to update the Exhibits to this Agreement as expressly permitted in this
Agreement, the Steering Committee shall not have any power to amend this
Agreement and will have only such powers as are specifically delegated to it
hereunder

                2.1.3 PROCEDURAL RULES FOR THE STEERING COMMITTEE.

                        (a) GENERALLY. Except as explicitly set forth in this
Section 2.1.3, the Steering Committee shall establish its own procedural rules
for its operation.

                        (b) VOTING. The Steering Committee shall take action by
unanimous consent of Northwest and Medarex, with each such Party having a single
vote, irrespective of the number of representatives actually in attendance at a
meeting, or by a written resolution signed by the designated representatives of
each of Northwest and Medarex.

        SECTION 2.2 PROGRESS REPORTS. Within thirty (30) days after the end of
each calendar year, or as otherwise required by the Steering Committee, each
Party shall provide to the other Party a written progress report, which shall
(a) describe any research, development or commercialization activities with
respect to Collaboration Targets or Collaboration Products and any other work
relating to the Collaboration Targets and Collaboration Products that it has
performed, or caused to be performed, since the last such report, (b) evaluate
the work performed in relation to the goals of this Agreement and the applicable
Project Plan, and (c) provide such

                                       8
<PAGE>   9

other information as may be required by this Agreement and the applicable
Project Plan or reasonably requested by the other Party relating to such
activities. In addition to the progress reports provided hereunder, it is
contemplated that the Parties will maintain informal communications through the
Steering Committee and their day-to-day activities under this Agreement.

        SECTION 2.3 DISPUTE RESOLUTION.

                2.3.1 STEERING COMMITTEE; CEOs. Any dispute that may arise
relating to the terms of this Agreement or the activities of the Parties
hereunder shall be brought to the attention of the Steering Committee, which
shall attempt in good faith to achieve a resolution. Either Party may convene a
special meeting of the Steering Committee for the purpose of resolving disputes.
If the Steering Committee is unable to resolve such a dispute within twenty (20)
days of the first presentation of such dispute to the Steering Committee, and
with respect to all other disputes, such dispute shall be referred to the Chief
Executive Officers of each of the Parties (or their respective designees) who
shall use their good faith efforts to mutually agree upon the proper course of
action to resolve the dispute.

                2.3.2 EXPERT; LITIGATION. If any dispute is not resolved by the
Chief Executive Officers of the Parties (or their designees) within ten (10)
business days after such dispute is referred to them pursuant to subsection
2.3.1 above, then either Party shall have the right (x) if such dispute relates
to Sections 1.2.3(a), (c) or (e), 1.2.6(a) (to the extent the dispute relates to
the determination of whether an Assay Candidate has met the applicable Assay
Success Criteria), 1.2.8 (to the extent the dispute relates to the selection of
a Lead Collaboration Antibody), or 1.3 (to the extent the dispute relates to the
determination of the activities to be undertaken pursuant to a Project Plan, but
not with respect to a dispute regarding which Party will perform any such
activities), to refer such dispute to an Expert for expedited arbitration as set
forth in subparagraphs 2.3.3 below, or (y) with respect to any other dispute,
including with respect to a Party's interpretation of, or any allegation of
breach of, this Agreement, to litigate such dispute in accordance with Section
11.5 or to pursue such other dispute resolution mechanism as the Parties may
agree.

                2.3.3 EXPERT PROCEEDINGS.

                        (a) With respect to disputes under subparagraph (x)
above that are not resolved by the Chief Executive Officers of the Parties (or
their designees) pursuant to Section 2.3.1, upon written request by either Party
to the other Party, the Parties shall promptly negotiate in good faith to
appoint a mutually acceptable disinterested, conflict-free individual not
affiliated with either Party, with scientific, technical and regulatory
experience with respect to the development of antibody-based products necessary
to resolve such dispute (an "Expert"). If the Parties are not able to agree
within five (5) days after the receipt by a Party of the written request in the
immediately preceding sentence, the CPR Institute for Dispute Resolution shall
be responsible for selecting an Expert within seven (7) days of being approached
by a Party. The fees and costs of the Expert and the CPR Institute for Dispute
Resolution shall be shared equally (50%) by the Parties.

                                       9
<PAGE>   10

                        (b) Within fifteen (15) days after the designation of
the Expert, the Parties shall each simultaneously submit to the Expert and one
another a written statement of their respective positions on such disagreement.
Each Party shall have five (5) days from receipt of the other Party's submission
to submit a written response thereto, which shall include any scientific and
technical information in support thereof. The Expert shall have the right to
meet with the Parties, either alone or together, as necessary to make a
determination.

                        (c) No later than thirty (30) days after the designation
of the Expert, the Expert shall make a determination by selecting the resolution
proposed by one of the Parties that as a whole is the most fair and reasonable
to the Parties in light of the totality of the circumstances and shall provide
the Parties with a written statement setting forth the basis of the
determination in connection therewith. The decision of the Expert shall be final
and conclusive, absent manifest error.

                                    ARTICLE 3
                                 GRANT OF RIGHTS

        SECTION 3.1 LICENSE GRANTS FOR COLLABORATION ACTIVITIES.

                3.1.1 MEDAREX GRANT. Subject to Section 3.3 and the other terms
and conditions of this Agreement, Medarex hereby grants to Northwest and its
Affiliates a co-exclusive (with Medarex and its Affiliates), fully-paid,
royalty-free license, with the right to sublicense solely as provided in
Sections 3.3.5 and 3.4, under the Medarex Technology and the Collaboration
Technology, in each case to (a) perform Northwest's activities under Section
1.2, and (b) jointly Exploit the Collaboration Products in accordance with this
Agreement.

                3.1.2 NORTHWEST GRANT. Subject to the terms and conditions of
this Agreement, Northwest hereby grants to Medarex and its Affiliates a
co-exclusive (with Northwest and its Affiliates), fully-paid, royalty-free
license, with the right to sublicense solely as provided in Section 3.4, under
the Northwest Technology and the Collaboration Technology, in each case to (a)
perform Medarex's activities under Section 1.2, and (b) jointly Exploit the
Collaboration Products in accordance with this Agreement.

        SECTION 3.2 PRODUCT TRADEMARKS FOR COLLABORATION PRODUCTS.

                3.2.1 MEDAREX GRANT. Subject to the terms and conditions of this
Agreement, Medarex hereby grants to Northwest and its Affiliates a royalty free,
fully paid, co-exclusive (with Medarex and its Affiliates), fully-paid,
royalty-free license, with the right to sublicense solely as provided in Section
3.4, to use the Product Trademarks to Exploit the Collaboration Products in
accordance with this Agreement.

                3.2.2 NORTHWEST GRANT. Subject to the terms and conditions of
this Agreement, Northwest hereby grants to Medarex and its Affiliates a royalty
free, fully paid, co-exclusive (with Northwest and its Affiliates), fully-paid,
royalty-free license, with the right to sublicense solely as provided in Section
3.4, to use the Product Trademarks to Exploit the Collaboration Products in
accordance with this Agreement.

                                       10
<PAGE>   11

        SECTION 3.3 EXCLUSIVITY, RESERVED RIGHTS AND PRE-EXISTING GRANTS.

                3.3.1 ANTIGEN EXCLUSIVITY. Subject to Sections 3.3.2 and 3.3.4,
the Parties acknowledge and agree that this Collaboration shall be exclusive
with respect to the Collaboration Targets and that no Party shall engage,
directly or indirectly, on behalf of itself or any other party, in the research,
development, commercialization or other Exploitation of antibody-based products
with respect to any Collaboration Target other than the Collaboration Products
and Unilateral Products as provided in this Agreement and any related agreements
between the Parties.

                3.3.2 RESEARCH AND COMMERCIALIZATION AGREEMENTS. Medarex shall
have the right to (a) grant licenses and other rights to other parties, under
the Medarex Technology for such parties to Exploit Antibody Products (but not
Collaboration Products) with respect to Antigens, including Collaboration
Targets, (b) transfer Medarex Know-How to such parties in connection therewith,
including by providing instruction with respect to the use and immunization of
HuMAb Mice and assistance with respect to the Mice-Related Technology, (c)
develop production processes for, and manufacture, such Antibody Products, and
(d) receive license fees, milestone payments, royalties and other remuneration
in connection therewith, but, in connection with clause (a), (b), (c) or (d)
above, not to otherwise actively participate in the clinical development or
commercialization of such Antibody Products by such parties (each agreement with
respect to the foregoing, a "Research and Commercialization Agreement").

                3.3.3 RETAINED RIGHTS.

                        (a) OTHER ANTIGENS. Notwithstanding anything in this
Agreement to the contrary, each Party does hereby retain the right to (i) enter
into collaborations with, and to grant licenses and other rights under its
respective Technology to, Third Parties to Exploit Antibody Products with
respect to Antigens other than Collaboration Targets, and/or (ii) independently
Exploit Antibody Products with respect to Antigens other than Collaboration
Targets; provided that Northwest's rights under this subsection (a) shall become
effective only after all eight (8) Collaboration Targets have been evaluated and
accepted as provided in Section 1.2.2.

                        (b) NON-ANTIBODY PRODUCTS. Notwithstanding anything in
this Agreement to the contrary, each Party does hereby retain the right to (i)
enter into collaborations with, and to grant licenses and other rights under its
respective Technology (other than Collaboration Technology, which shall be
governed by Section 7.1.5) to, Third Parties to Exploit products other than
antibody-based products with respect to Collaboration Targets without use or
reference to the other Party's technology, and/or (ii) independently Exploit
products other than antibody-based products with respect to Collaboration
Targets.

                3.3.4 EXISTING GRANTS. The Parties further acknowledge and agree
that pursuant to the Cross-License Agreement, Medarex has granted a
non-exclusive license under certain Medarex Patents to Exploit Antibody
Products, including Collaboration Products, `With respect to Antigens, including
the Collaboration Targets, in the Territory.

                                       11
<PAGE>   12

                3.3.5 CROSS LICENSE AGREEMENT. The Cross-License Agreement
prohibits Medarex from granting commercialization rights to the same Antibody
Product, whether by license or sublicense, under certain Medarex Technology to
more than one party in a territory. The Parties shall structure their respective
commercialization rights in each country in the Territory, in accordance with
this Section 3.3.5, so as to comply with the requirements of the Cross-License
Agreement and shall use good faith efforts to ensure that any such structure
preserves the intended economic benefits of the Collaboration to the Parties.

                        (a) So long as the Cross-License Agreement is in effect,
if the Steering Committee desires to grant a sublicense with respect to
commercialization of a Collaboration Product pursuant to Section 3.4, then the
Steering Committee shall provide Medarex with written notice thereof, which
shall set forth in reasonable detail the terms and conditions of such
sublicense, the Medarex Technology and Collaboration Product involved, and the
identity of the proposed sublicensee. Upon receipt of such notice, Medarex shall
make a good faith determination as to whether such Medarex Technology is subject
to the sublicense restrictions contained in the Cross-License Agreement.

                        (b) To the extent that Medarex determines that such
Medarex Technology is not subject to the sublicense restrictions contained in
the Cross-License Agreement, Medarex shall so notify the Steering Committee in
writing and the Collaboration thereafter shall have the right to grant such
sublicense, subject to Section 3.4.

                        (c) To the extent that Medarex determines that all or
part of such Medarex Technology is subject to the sublicense restrictions
contained in the Cross-License Agreement, Medarex shall so notify the Steering
Committee in writing. The Parties shall then meet to discuss in good faith how
to proceed in order to optimize the commercialization of the applicable
Collaboration Product hereunder while complying with the requirements of the
Cross-License Agreement.

        SECTION 3.4 SUBLICENSES. Subject to Section 3.3.5, each Party shall have
the right to grant to Third Parties sublicenses under the licenses granted in
Sections 3.1 and 3.2 only with the prior written consent of the Steering
Committee, not to be unreasonably withheld or delayed; provided, however, that
the grant of any such sublicense shall not relieve the sublicensing Party of its
obligations under this Agreement. With respect to any proposed sublicense, the
sublicensing Party shall provide the Steering Committee with written notice
setting forth in reasonable detail the nature of such sublicense and the
identity of the sublicensee.

        SECTION 3.5 LICENSE LIMITATIONS. Each Party hereby covenants to the
other Party that neither such first Party nor any of its Affiliates, licensees
or sublicensees shall use or practice the Technology of such other Party (other
than the Collaboration Technology, which shall be governed by Section 7.1.5),
directly or indirectly, on behalf of itself or any other party, for any purpose
other than as permitted under Section 3.1 and in particular, but without
limiting the generality of the foregoing, for any research, development,
commercialization or other Exploitation of an Antibody Product or any other
product or method, other than a Collaboration Product or a Unilateral Product as
provided hereunder.

                                       12
<PAGE>   13

        SECTION 3.6 NO OTHER RIGHTS. For the avoidance of doubt, Medarex: and
its Affiliates shall have no right, express or implied, with respect to the
Northwest Technology and Northwest and its Affiliates shall have no right,
express or implied, with respect to the Medarex Technology, in each case except
as expressly provided in Section 3.1.

                                    ARTICLE 4
                              FINANCIAL PROVISIONS

        SECTION 4.1 PROFIT AND EXPENSE ALLOCATION WITH RESPECT TO COLLABORATION
PRODUCTS.

                4.1.1 NET PROFITS AND NET LOSSES. Except as otherwise provided
in this Agreement, * , as applicable, with respect to the Collaboration
Products, as set forth in this Section. Within thirty (30) days after the end of
each calendar quarter in which Net Profits or Net Losses are recognized with
respect to a Collaboration Product, each Party shall provide the other Party
with a statement detailing its Net Profits or Net Losses for such Collaboration
Product for such calendar quarter on a country-by-country basis, which statement
shall set forth in reasonable detail any Net Sales by such Party or its
Affiliates, any Commercialization Expenses and any Other Operating
(Income)/Expense, including a detailed breakdown of the components of the
foregoing, with respect to such Collaboration Product, provided that such
Commercialization Expenses (including the components thereof) may not exceed (or
be projected to exceed) the amount set forth in the applicable Project Budget
with respect to the commercialization activities set forth in the applicable
Project Plan by more than ten percent (10%) without the approval of the Steering
Committee ("AUTHORIZED COMMERCIALIZATION EXPENSES"). Within forty-five (45) days
after the end of each calendar quarter, the Parties shall make payments to one
another so that * , as applicable, for such calendar quarter for each
Collaboration Product.

                4.1.2 RESEARCH AND DEVELOPMENT EXPENSES. Except as otherwise
provided in this Agreement, * of all Authorized R&D Expenses (as defined below)
incurred by or on behalf of the Parties in connection with their activities
other than the Northwest Research Activities and the Medarex Research
Activities. Within thirty (30) days after the end of each calendar quarter, each
Party shall furnish the Steering Committee with a statement (a) detailing the
costs and expenses actually incurred in connection with the research and
development activities (including Phase IV and any other post-Regulatory
Approval research and development activities) performed by or on behalf of such
Party during such calendar quarter, provided that such costs or expenses may not
exceed (or be projected to exceed) the amounts set forth in the relevant Project
Budget with respect to such research and development activities by more than ten
percent (10%) without the approval of the Steering Committee (the "AUTHORIZED
R&D EXPENSES") and (b) comparing such expenses to date with the projections set
forth in the Project Budget. Within forty-five (45) days after the end of each
calendar quarter, Medarex and Northwest shall make payments to one another so
that * of the total Authorized R&D Expenses for such calendar quarter.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       13
<PAGE>   14

        SECTION 4.2 PAYMENT METHOD. All amounts due by one Party hereunder shall
be paid in U.S. dollars by wire transfer in immediately available funds to an
account designated by the receiving Party. Any payments or portions thereof due
hereunder which are not paid on the date such payments are due under this
Agreement shall bear interest at a rate equal to the lesser of the prime rate as
published in The Wall Street Journal, Eastern Edition, on the first day of each
calendar quarter in which such payments are overdue, plus two percentage points,
or the maximum rate permitted by law, calculated on the number of days such
payment is delinquent, compounded monthly.

        SECTION 4.3 CURRENCY; FOREIGN PAYMENTS. If any currency conversion shall
be required in connection with any payment hereunder, such conversion shall be
made by using the exchange rate for the purchase of U.S. dollars as published in
The Wall Street Journal, Eastern Edition, on the last business day of the
calendar quarter to which such payments relate. If at any time legal
restrictions prevent the prompt remittance of any Net Profits with respect to
Net Sales in any jurisdiction, the applicable Party may notify the other and
make such payments by depositing the amount thereof in local currency in a bank
account or other depository in such country in the name of the receiving Party
or its designee, and such Party shall have no further obligations under this
Agreement with respect thereto.

        SECTION 4.4 TAXES. A Party may deduct from any amounts it is required to
pay pursuant to this Agreement an amount equal to that withheld for or due on
account of any taxes (other than taxes imposed on or measured by net income) or
similar governmental charge imposed by a jurisdiction other than the United
States ("WITHHOLDING TAXES"). At the receiving Party's request, the paying Party
shall provide the receiving Party a certificate evidencing payment of any
Withholding Taxes hereunder and shall reasonably assist the receiving Party, at
the receiving Party's expense, to obtain the benefit of any applicable tax
treaty.

        SECTION 4.5 RECORDS RETENTION; AUDIT.

                4.5.1 RECORD RETENTION. Each Party shall maintain (and shall
ensure that its Affiliates and sublicensees shall maintain) complete and
accurate books, records and accounts that fairly reflect their respective (a)
Authorized R&D Expenses, Authorized Commercialization Expenses, Other Operating
(Income)/Expenses, any costs and expenses reimbursable under Article 7, and any
other costs and expenses reimbursable or otherwise shared by the Parties
hereunder (collectively, the "COLLABORATION EXPENSES"), and (b) Net Sales of
Collaboration Products and Net Profits and Net Losses with respect to
Collaboration Products, in each case in sufficient detail to confirm the
accuracy of any payments required hereunder and in accordance with GAAP, which
books, records and accounts shall be retained by such party until the later of
(i) three (3) years after the end of the period to which such books, records and
accounts pertain, and (ii) the expiration of the applicable tax statute of
limitations (or any extensions thereof), or for such longer period as may be
required by Applicable Law.

                4.5.2 AUDIT. Each Party shall have the right to have an
independent certified public accounting firm of nationally recognized standing,
reasonably acceptable to the audited Party, to have access during normal
business hours, and upon reasonable prior written notice, to

                                       14
<PAGE>   15

such of the records of the other Party (and its Affiliates and sublicensees) as
may be reasonably necessary to verify the accuracy of such Collaboration
Expenses, Net Sales, or Net Profits or Net Losses, as applicable, for any
calendar quarter ending not more than thirty-six (36) months prior to the date
of such request; provided, however, that neither Party shall have the right to
conduct more than one such audit in any twelve (12)-month period. The accounting
firm shall disclose to each Party whether such Collaboration Expenses, Net
Sales, or Net Profits or Net Losses, as applicable, are correct or incorrect and
the specific details concerning any discrepancies. No other information shall be
provided to the requesting Party. The requesting Party shall bear the cost of
such audit unless the audit reveals a variance of more than five percent (5%)
from the reported results, in which case the audited Party shall bear the cost
of the audit. The results of such accounting firm shall be final, absent
manifest error.

                4.5.3 PAYMENT OF ADDITIONAL AMOUNTS. If, based on the results of
such audit, additional payments are owed by a Party under this Agreement, such
Party shall make such additional payments, with interest from the date
originally due at the rate of * per month, within sixty (60) days after the date
on which such accounting firm's written report is delivered to such Party.

                4.5.4 CONFIDENTIALITY. The auditing Party shall treat all
information subject to review under this Section 4.5 in accordance with the
confidentiality provisions of Article 6 and shall cause its accounting firm to
enter into a reasonably acceptable confidentiality agreement with the audited
Party obligating such firm to maintain all such financial information in
confidence pursuant to such confidentiality agreement.

                                    ARTICLE 5
          UNILATERAL AND THIRD PARTY DEVELOPMENT AND COMMERCIALIZATION

        SECTION 5.1 UNILATERAL DEVELOPMENT AND COMMERCIALIZATION.

                5.1.1 OPTING-OUT BY A PARTY. Each Party (i.e., Medarex, on the
one hand, and Northwest, on the other hand) (the "OPTING-OUT PARTY") shall have
the right, on thirty (30) days' written notice to the other (an "OPT-OUT
NOTICE"), to elect not to proceed with the research, development and
commercialization ("OPT-OUT") of all Collaboration Products with respect to a
given Collaboration Target, provided that such Party shall * associated with the
research and development activities with respect to such Collaboration
Product(s) that such Party has committed to in the applicable Project Budget as
necessary to complete that phase of research and development (e.g., toxicology
studies in support of an IND or Phase I, Phase II or Phase III studies) that was
under way when such Party Opted-Out. By way of clarification, if a Party
Opts-Out of a Collaboration Product with respect to a Collaboration Target, such
Party will be deemed to have Opted-Out with respect to all Antibody Products
with respect to the same Collaboration Target.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       15
<PAGE>   16

                5.1.2 RIGHTS AND OBLIGATIONS OF PARTIES WITH RESPECT TO
UNILATERAL PRODUCTS.

                        (a) UNILATERAL DEVELOPMENT AND COMMERCIALIZATION. Upon
receipt by a Party of an Opt-Out Notice, the receiving Party shall have the
right, on written notice to the Opting-Out Party within thirty (30) days
following receipt of the Opt-Out Notice (an "ELECTION NOTICE"), to proceed
unilaterally with the research, development and commercialization of all
Collaboration Antibodies to the applicable Collaboration Target (each, a
"UNILATERAL PRODUCT") pursuant to the separate agreement with the Opting-Out
Party attached hereto as Appendix D-1 or Appendix D-2, as applicable (each, a
"UNILATERAL DEVELOPMENT AND COMMERCIALIZATION AGREEMENT"). Upon receipt by
Medarex of an Election Notice from Northwest with respect to a Collaboration
Target, the Unilateral Development and Commercialization Agreement set forth in
Appendix D-1 shall be automatically amended to include such Collaboration Target
and any Antibody Products with respect thereto. Upon receipt by Northwest of an
Election Notice from Medarex with respect to a Collaboration Target, the
Unilateral Development and Commercialization Agreement set forth in Appendix D-2
shall be automatically amended to include such Collaboration Target and any
Antibody Products with respect thereto. Upon such amendment of a Unilateral
Development and Commercialization Agreement pursuant to this Section 5.1.2, the
applicable Antigen shall cease to be a Collaboration Target and Appendix Q shall
be amended accordingly, and any licenses granted pursuant to Article 3, with
respect to such Antigen and any Antibodies and Antibody Products with respect
thereto, shall terminate. The Parties shall work together to ensure a smooth and
orderly transition of the Unilateral Products to the non-Opting-Out Party,
including the assignment of any contracts with respect to the Exploitation of
such Unilateral Products to the non-Opting-Out Party, and the assumption by the
non-Opting-Out Party of any obligations thereunder. Except for the obligations
provided for in Section 5.1.1, the Opting-Out Party shall have (x) no further
financial obligation to support or otherwise fund any additional efforts in
respect of such Unilateral Product, and (y) no obligation, responsibility, or
authority regarding such additional efforts in respect of such Unilateral
Product. In the event that neither Party elects to proceed with the research,
development or commercialization of any Collaboration Product with respect to a
Collaboration Target, the rights and obligations of the Parties with respect to
such Collaboration Target shall be governed by Sections 5.2 and 5.3.

                        (b) OPT-OUT OF UNILATERAL PRODUCTS. If, at any time, the
non-Opting Out Party elects to Opt-Out of all Unilateral Products with respect
to a Unilateral Target (as defined in the applicable Unilateral Development and
Commercialization Agreement) pursuant to such Unilateral Development and
Commercialization Agreement and the other Party does not elect to proceed
unilaterally with the research, development and commercialization of such
Unilateral Products, all such Unilateral Products shall become Dormant Products
pursuant to Section 5.3 and the non-Opting Out Party shall, without any
additional consideration, assign fifty percent (50%) of its right, title and
interest in and to any Product Trademark and all Regulatory Documentation with
respect to such Unilateral Products, including any Regulatory Approvals and
applications therefor (but excluding any Regulatory Documentation comprising
Production Process Technology, including any drug master file), to the other
Party.

                                       16
<PAGE>   17

        SECTION 5.2 THIRD-PARTY RESEARCH, DEVELOPMENT AND COMMERCIALIZATION OF
COLLABORATION PRODUCTS. The Parties shall have the right, at any time with
respect to a Collaboration Product, to license to Third Parties rights with
respect to the research, development, manufacture or commercialization of such
Collaboration Product on such terms and conditions as the Parties may mutually
agree; provided that (a) any such sublicense with respect to the Medarex
Technology shall be governed by the procedures set forth in Sections 3.3.5 and
3.4; and (b) any disputes between the Parties as to whether or not to grant such
a license shall not be subject to litigation or any other Third Party dispute
resolution mechanism.

        SECTION 5.3 DORMANT PRODUCTS. If the Parties do not elect to proceed
with the research, development or commercialization of a particular
Collaboration Product with respect to a Collaboration Target, and the Parties
have not licensed rights to such Collaboration Product to a Third Party
pursuant, to Section 5.2 that would be inconsistent therewith, (each, a "DORMANT
PRODUCT") either Party shall have the right at any time, subject to Section 3.3,
to bring such Collaboration Product to the Steering Committee to discuss whether
to initiate or reinitiate the research, development or commercialization of such
Dormant Product. The initiating Party shall specify the reasons for proposing to
initiate or reinitiate, such research, development or commercialization. If,
within thirty (30) days after the receipt of such notice, the other Party fails
to notify the interested Party in writing that it wishes to participate in the
research, development or commercialization of such Dormant Product, then the
interested Party shall have the right to pursue research, development or
commercialization of such Dormant Product as a Unilateral Product pursuant to
Section 5.1, provided that no Collaboration Product with respect to the same
Collaboration Target as such Dormant Product is being Exploited under this
Agreement or by the other Party under a Unilateral Development and
Commercialization Agreement.

                                    ARTICLE 6
                                 CONFIDENTIALITY

        SECTION 6.1 DEFINITION. "Confidential Information" of a Party shall mean
all information and know-how and any tangible embodiments thereof provided by or
on behalf of such Party to the other Party either in connection with the
discussions and negotiations pertaining to this Agreement or in the course of
performing this Agreement, including data; knowledge; practices; processes;
ideas; research plans, engineering designs and drawings, research data,
manufacturing processes and techniques; scientific, manufacturing, marketing and
business plans; and financial and personnel matters relating to the disclosing
Party or to its present or future products, sales, suppliers, customers,
employees, investors or business. For purposes of this Agreement,
notwithstanding the Party that disclosed such information or know-how, all
Northwest Know-How and all information or know-how with respect thereto, shall
be Confidential Information of Northwest and all Medarex Know-How, including all
Mice-Related Know-How and all Production Process Know-How, and all information
and know-how with respect thereto, shall be Confidential Information of Medarex.

                                       17
<PAGE>   18

        SECTION 6.2 EXCLUSIONS. Notwithstanding the foregoing, information or
know-how of a Party shall not be deemed Confidential Information with respect to
a receiving Party for purposes of this Agreement if such information or
know-how:

                (a) was already known to the receiving Party or its Affiliates,
other than under an obligation of confidentiality or non-use, at the time of
disclosure to, or, with respect to Know-How, discovery or development by, such
receiving Party;

                (b) was generally available or known to parties reasonably
skilled in the field to which such information or know-how pertains, or was
otherwise part of the public domain, at the time of its disclosure to, or, with
respect to Know-How, discovery or development by, such receiving Party;

                (c) became generally available or known to parties reasonably
skilled in the field to which such information or know-how pertains, or
otherwise became part of the public domain, after its disclosure to, or, with
respect to Know-How, discovery or development by, such receiving Party through
no fault of a Party other than the Party that Controls such information and
know-how;

                (d) was disclosed to such receiving Party or its Affiliates,
other than under an obligation of confidentiality or non-use, by a third party
who had no obligation to the Party that Controls such information and know-how
not to disclose such information or know-how to others; or

                (e) was independently discovered or developed by such receiving
Party or its Affiliates, as evidenced by their written records, without the use
of, and by personnel who had not access to, Confidential Information belonging
to the Party that Controls such information and know-how.

Specific aspects or details of Confidential Information shall not be deemed to
be within the public domain or in the possession of a Party merely because the
Confidential Information is embraced by more general information in the public
domain or in the possession of such Party. Further, any combination of
Confidential Information shall not be considered in the public domain or in the
possession of a Party merely because individual elements of such Confidential
Information are in the public domain or in the possession of such Party unless
the combination and its principles are in the public domain or in the possession
of such Party.

        SECTION 6.3 DISCLOSURE AND USE RESTRICTION. Except as expressly provided
herein, the Parties agree that, for the Term and for five (5) years thereafter,
each Party and its Affiliates and sublicensees shall keep completely
confidential and shall not publish or otherwise disclose and shall not use for
any purpose except for the purposes contemplated by this Agreement any
Confidential Information of the other Party, its Affiliates or sublicensees.

                                       18
<PAGE>   19

        SECTION 6.4 AUTHORIZED DISCLOSURE. Each Party may disclose Confidential
Information of the other Party to the extent that such disclosure is:

                6.4.1 REQUIRED BY GOVERNMENTAL ORDER. Made in response to a
valid order of a court of competent jurisdiction or other supra-national,
federal, national, regional, state, provincial or local governmental or
regulatory body of competent jurisdiction; provided, however that such Party
shall first have given notice to such other Party and given such other Party a
reasonable opportunity to quash such order and to obtain a protective order
requiring that the Confidential Information and documents that are the subject
of such order be held in confidence by such court or agency or, if disclosed, be
used only for the purposes for which the order was issued; and provided further
that if a disclosure order is not quashed or a protective order is not obtained,
the Confidential Information disclosed in response to such court or governmental
order shall be limited to that information which is legally required to be
disclosed in response to such court or governmental order;

                6.4.2 REQUIRED BY LAW. Otherwise required by law; provided,
however, that the disclosing Party shall provide such other Party with notice of
such disclosure in advance thereof to the extent practicable;

                6.4.3 REQUIRED BY REGULATORY AUTHORITY. Made by such Party to
the Regulatory Authorities as required in connection with any filing,
application or request for Regulatory Approval; provided, however, that
reasonable measures shall be taken to assure confidential treatment of such
information;

                6.4.4 REQUIRED BY AGREEMENT. Made by such Party, in connection
with the performance of this Agreement, to Affiliates, permitted sublicensees,
research parties, employees, consultants, representatives or agents, each of
whom prior to disclosure must be bound by obligations of confidentiality and
non-use at least equivalent in scope to those set forth in this Article 6; or

                6.4.5 REQUIRED BY CERTAIN THIRD PARTIES. Made by such Party to
existing or potential acquirers or merger candidates; existing or potential
pharmaceutical collaborators (to the extent contemplated hereunder); investment
bankers; existing or potential investors, venture capital firms or other
financial institutions or investors for purposes of obtaining financing; or
Affiliates, each of whom prior to disclosure must be bound by obligations of
confidentiality and non-use at least equivalent in scope to those set forth in
this Article 6. Notwithstanding this Section 6.4.5, neither Party shall disclose
any item of the other Party's Confidential Information to any existing or
potential acquirer or merger partner that is substantially involved in the
Exploitation of Antibodies or Antibody Products without first providing such
other Party with reasonable advance written notice of each such disclosure.

        SECTION 6.5 USE OF NAME. Each Party may use the name, insignia, symbol,
trademark, trade name or logotype of the other Party only (a) in connection with
announcements and other permitted disclosures relating to this Agreement and the
activities contemplated hereby, (b) as required by Applicable Law, and (c)
otherwise as agreed in writing by such other Party.

                                       19
<PAGE>   20

        SECTION 6.6 PRESS RELEASES. Press releases or other similar public
communication by either Party relating to this Agreement, shall be approved in
advance by the other Party, which approval shall not be unreasonably withheld or
delayed, except for those communications required by Applicable Law (which shall
be provided to the other Party as soon as practicable after the release or
communication thereof), disclosures of information for which consent has
previously been obtained, and information of a similar nature to that which has
been previously disclosed publicly with respect to this Agreement, each of which
shall not require advance approval.

        SECTION 6.7 PUBLICATIONS. The Parties acknowledge that scientific
lead-time is a key element of the value of the research and development
activities under the Collaboration and further agree that scientific
publications must be strictly monitored to prevent any adverse effect from
premature publication of results of the research or development activities
hereunder. At least sixty (60) days prior to submission of any material related
to the research or development activities hereunder for publication or
presentation, the submitting Party shall provide to the other Party a draft of
such material for its review and comment. The receiving Party shall provide any
comments to the submitting Party within sixty (60) days of receipt of such
materials. No publication or presentation with respect to the research or
development activities hereunder shall be made unless and until the other
Party's comments on the proposed publication or presentation have been addressed
and changes have been agreed upon and any information determined by the other
Party to be Confidential Information has been removed. If requested in writing
by the other Party, the submitting Party shall withhold material from submission
for publication or presentation for an additional sixty (60) days to allow for
the filing of a patent application or the taking of such measures to establish
and preserve proprietary rights in the information in the material being
submitted for publication or presentation.

                                    ARTICLE 7
                              INTELLECTUAL PROPERTY

        SECTION 7.1 INTELLECTUAL PROPERTY OWNERSHIP.

                7.1.1 OWNERSHIP OF MEDAREX TECHNOLOGY. Subject to the license
grants to Northwest under Article 3, as between the Parties, Medarex shall own
and retain all right, title and interest in and to any and all: (a) Information
and Inventions that are conceived, discovered, developed or otherwise made, as
necessary to establish authorship, inventorship or ownership under Applicable
Law, by or on behalf of Medarex (or its Affiliates or its licensees or
sublicensees (other than Northwest and its Affiliates)), whether or not patented
or patentable, and any and all Patent and other intellectual property rights
with respect thereto, except to the extent that any such Information and
Inventions, or any Patent or other intellectual property rights with respect
thereto, are Collaboration Technology; (b) other Information and Inventions, and
Patent and other intellectual property rights that are Controlled (other than
pursuant to the license grants set forth in Article 3) by Medarex, its
Affiliates or its licensees or sublicensees (other than Northwest), and (c)
other Medarex Technology.

                7.1.2 OWNERSHIP OF NORTHWEST TECHNOLOGY. Subject to Section
7.1.3 and the license grants to Medarex under Article 3, as between the Parties,
Northwest shall own and retain

                                       20
<PAGE>   21

all right, title and interest in and to any and all: (a) Information and
Inventions that are conceived, discovered, developed or otherwise made, as
necessary to establish authorship, inventorship or ownership under Applicable
Law, by or on behalf of Northwest (or its Affiliates or its licensees or
sublicensees (other than Medarex and its Affiliates)), whether or not patented
or patentable, and any and all Patent and other intellectual property rights
with respect thereto, except to the extent that any such Information and
Inventions, or any Patent or other intellectual property rights with respect
thereto, are Collaboration Technology or Mice Materials or Mice-Related
Technology, (b) other Information and Inventions, and Patent and other
intellectual property rights that are Controlled (other than pursuant to the
license grants set forth in Article 3) by Northwest, its Affiliates or its
licensees or sublicensees (other than Medarex); and (c) other Northwest
Technology.

                7.1.3 OWNERSHIP OF MICE-RELATED TECHNOLOGY. Subject to the
license grants to Northwest under Article 3, as between the Parties, Medarex
shall own and retain all right, title and interest in and to all Mice Materials
and Mice-Related Technology, including any and all information and Inventions
with respect to the Mice Materials or the Mice-Related Technology (including any
Improvements thereto) that are conceived; discovered, developed or otherwise
made, as necessary to establish authorship, inventorship or ownership under
Applicable Law, by or on behalf of Northwest, its Affiliates or its licensees or
sublicensees (other than Medarex and its Affiliates), whether or not patented or
patentable, and any and all Patent and other intellectual property rights with
respect thereto. Northwest acknowledges and agrees that (a) the licenses granted
to it pursuant to Article 3 permit Northwest to use Mice Materials and
Mice-Related Technology solely for the Exploitation of Collaboration Products as
provided in this Agreement, (b) Northwest has no right to use the HuMAb Mice or
to discover, develop or otherwise make Improvements with respect to Mice
Materials and Mice-Related Technology under such grants, and (c) neither it, nor
any of its Affiliates, licensees or sublicensees, will engage, directly or
indirectly, in activities designed to, or otherwise undertake or attempt, either
on behalf of itself or another, to discover, develop or make any Information and
Inventions that relate to the Mice Materials or the Mice-Related Technology.
Accordingly, Northwest shall promptly disclose to Medarex in writing, the
conception or reduction to practice, or the discovery, development or making of
any Mice Material or Mice-Related Technology and shall, and does hereby, assign,
and shall cause its Affiliates, licensees and sublicensees to so assign, to
Medarex, without additional compensation, all of their respective rights, titles
and interests in and to any Mice Material or Mice-Related Technology.

                7.1.4 OWNERSHIP OF PRODUCTION PROCESS TECHNOLOGY. Medarex shall
own and retain all right, title and interest in and to the Production Process
Technology, including any and all Information and Inventions with respect to
such Production Process Technology (including any Improvements thereto) that are
conceived, discovered, developed or otherwise made, as necessary to establish
authorship, inventorship or ownership under Applicable Law, by or on behalf of
Medarex, its Affiliates or, to the extent permitted, its sublicensees, whether
or not patented or patentable, and any and all Patent and other intellectual
property rights with respect thereto. Except as the Parties may otherwise
expressly agree, Northwest shall not have any rights, express or implied, under
this Agreement with respect to the Production Process Technology and nothing in
this Agreement is intended to or shall be interpreted as granting Northwest any
license to the Production Process Technology, whether subordinate or dominant

                                       21
<PAGE>   22

to any other Technology. Medarex shall have the right to submit any of its
Production Process Know-How with respect to a Collaboration Product directly to
the Regulatory Authorities using a drug master file, or any foreign equivalent
that is designed to protect Medarex's Confidential Information, which Know-How
and filing shall, notwithstanding Section 7.1.7 or any other provision of this
Agreement, be and remain the sole and exclusive property of Medarex.

                7.1.5 OWNERSHIP OF COLLABORATION TECHNOLOGY. Subject to Sections
7.1.3 and 7.1.4 and the license grants under Article 3, the Parties shall each
own an equal, undivided interest in any Collaboration Technology; provided,
however that, except as otherwise expressly provided in this Agreement, neither
a Party nor any of its Affiliates, licensees or sublicensees shall, directly or
indirectly, Exploit any Collaboration Technology, or any intellectual property
rights with respect thereto, without the consent of the other Party, not to be
unreasonably withheld or delayed, except that each Party shall have the right to
Exploit such Collaboration Technology for research and discovery purposes (as
opposed to the development, commercialization or other Exploitation of products
or technology resulting therefrom), and to license others to do so, without the
consent of the other Party. Each Party shall promptly disclose to the other
Party in writing, and shall cause its Affiliates, licensees and sublicensees to
so disclose, the development, making, conception or reduction to practice of any
Collaboration Technology, and shall, and does hereby, assign, and shall cause
its Affiliates, licensees and sublicensees to so assign, to the other Party,
without additional compensation, such right, title and interest in and to any
Collaboration Technology as well as any intellectual property rights with
respect thereto, as is necessary to fully effect the joint ownership provided
for in the foregoing sentence.

                7.1.6 OWNERSHIP OF PRODUCT TRADEMARKS. Subject to the license
grants in Article 3, the Parties shall each own an equal, undivided interest in
each Product Trademark with respect to a Collaboration Product. In the event
that a Party Opts-Out with respect to a Collaboration Product, it shall, without
any additional consideration, assign all of its right, title and interest in and
to any Product Trademark with respect to such Collaboration Product or
Unilateral Product to the non-Opting-Out Party; provided, however that each
Party shall retain all of its right, title and interest in and to any Product
Trademarks with respect to Dormant Products.

                7.1.7 FILING FOR REGULATORY APPROVALS; OWNERSHIP OF REGULATORY
DOCUMENTATION.

                        (a) Subject to the license grants in Article 3, all
filings for Regulatory Approvals with respect to a Collaboration Product shall
be * . With respect to the first Collaboration Product and any other
Collaboration Products with respect to the same Collaboration Target, the
filings for Regulatory Approvals * or its designee. With respect to the first
Collaboration Product with respect to the next Collaboration Target, and any
other Collaboration Products with respect to the same Collaboration Target, the
filings for Regulatory Approvals * or its designee.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       22
<PAGE>   23

                        (b) Subject to the license grants in Article 3, each
Party shall, to the extent permitted by law, have an equal, undivided interest
in all other Regulatory Documentation, provided that Regulatory Documentation
containing or comprising Production Process Know-How shall be and remain the
sole and exclusive property of Medarex. Subject to the foregoing sentence, each
Party shall promptly (a) disclose to the other Party in writing, and shall cause
its Affiliates, licensees and sublicensees to so disclose, such other Regulatory
Documentation, and (b) assign, or cause its Affiliates, licensees or
sublicensees to assign, to the other Party, without additional compensation,
such right, title and interest in and to such other Regulatory Documentation as
is necessary to fully effect the joint ownership provided for in the foregoing
sentence.

                        (c) Each non-Opting-Out Party shall have the right to
file for all Regulatory Approvals with respect to its Unilateral Products in its
own name. In the event that a Party Opts-Out with respect to a Collaboration
Product, it shall transfer and assign all of its right, title and interest in
and to all Regulatory Documentation with respect to such Collaboration Product,
including any Regulatory Approvals and applications therefor (but excluding any
Regulatory Documentation comprising Production Process Technology, including any
drug master file), to the non-Opting Out Party (or its designee); provided,
however, that each Party shall retain any of its right, title and interest in
and to-any Regulatory Documentation with respect to a Dormant Product.
Notwithstanding the sponsorship of any Regulatory Approval or ownership of any
other Regulatory Documentation, each Party shall have the right to use and
reference any of the Regulatory Documentation in connection with the
Exploitation of Collaboration Products as provided in this Agreement.

        SECTION 7.2 PROSECUTION OF PATENTS AND TRADEMARKS.

                7.2.1 MEDAREX RIGHTS. As between the Parties, Medarex shall,
subject to Section 7.2.5, have the sole right, at its cost and expense, to
obtain, prosecute and maintain throughout the world the Medarex. Patents,
including the Mice-Related Patents and the Production Process Patents; provided,
however, that Northwest shall reimburse Medarex for fifty percent (501/6) of the
reasonable out-of-pocket costs incurred by Medarex for filing, prosecuting and
maintaining Mice-Related Patents and Production Process Patents filed after the
Effective Date, to the extent that they claim or cover the Exploitation of
Collaboration Products.

                7.2.2 NORTHWEST RIGHTS. As between the Parties, Northwest shall,
subject to Section 7.2.5, have the sole right, at its cost and expense, to
obtain, prosecute and maintain throughout the world the Northwest Patents.

                7.2.3 COLLABORATION TECHNOLOGY AND PRODUCT TRADEMARKS.

                        (a) FILINGS OF PATENTS. Subject to Section 7.2.6, the
Parties shall, and shall cause their respective Affiliates, licensees and
sublicensees, as applicable, to, cooperate with one another with respect to the
filing, prosecution and maintenance of all Collaboration Patents, including by
selecting outside counsel, reasonably acceptable to the Parties, to handle such
filing, prosecution and maintenance. The Parties shall share equally in the
expenses

                                       23
<PAGE>   24

associated with the filing, prosecution (including any interferences, reissue
proceedings and reexaminations) and maintenance of all Collaboration Patents.

                        (b) FILINGS OF PRODUCT TRADEMARKS. The Steering
Committee, with respect to a Collaboration Product, shall supervise and direct
the filing, prosecution and maintenance of the registrations of the Product
Trademarks for such Collaboration Product. The Steering Committee shall provide
each Party with (i) drafts of any new application to register a Product
Trademark prior to filing that application, allowing adequate time for review
and comment by the Parties if possible; provided, however, the Steering
Committee shall not be obligated to delay the filing of any application; and
(ii) copies of all correspondence from any and all Trademark offices concerning
Product Trademark registrations and an opportunity to comment on any proposed
responses, voluntary amendments and submissions of any kind to be made to any
and all such Trademark offices. Subject to Section 7.2.6, the Parties shall
share equally in the expenses associated with the filing, prosecution and
maintenance of such Product Trademark registrations.

                7.2.4 COOPERATION. Each Party shall, and shall cause its
Affiliates, licensees and sublicensees, as applicable, to, cooperate fully in
the preparation, filing, prosecution, and maintenance of the other Party's
Patents and the Product Trademarks. Such cooperation includes (a) promptly
executing all papers and instruments and requiring employees to execute such
papers and instruments as reasonable and appropriate so as to enable such other
Party or the Steering Committee, as applicable, to file, prosecute, and maintain
its Patents in any country; and (b) promptly informing such other Party of
matters that may affect the preparation, filing, prosecution, or maintenance of
any such Patents.

                7.2.5 PATENT FILINGS. Northwest covenants not to, and to cause
its Affiliates, licensees and sublicensees, as applicable, not to, file any
patent application disclosing or claiming any Information and Inventions
comprising any Medarex Technology or the Exploitation thereof, without Medarex's
prior written consent, which consent shall not be unreasonably withheld or
delayed. Medarex covenants not to, and to cause its Affiliates, licensees and
sublicensees, as applicable, not to, file any patent application disclosing or
claiming any Information and Inventions comprising any Northwest Technology or
the Exploitation thereof, without Northwest's prior written consent, which
consent shall not be unreasonably withheld or delayed.

                7.2.6 ELECTION NOT TO PROSECUTE. If a Party elects not (a) to
pursue the filing, prosecution or maintenance of a Collaboration Patent in a
particular country, (b) to pursue the registration, prosecution or maintenance
of a Product Trademark in a particular country, or (c) to take any other action
with respect to Collaboration Technology or a Product Trademark in a particular
country that is necessary or reasonably useful to establish or preserve rights
thereto, then in each such case such Party shall so notify the other Party
promptly in writing and in good time to enable such other Party to meet any
deadlines by which an action must be taken to establish or preserve any such
rights in such Collaboration Technology or Product Trademark, as applicable, in
such country. Upon receipt of each such notice by such other Party or if, at any
time, such Party fails to initiate any such action within thirty (30) days after
a request by such other Party that it do so (or thereafter diligently pursue
such action), such other Party shall have

                                       24
<PAGE>   25

the right, but not the obligation, to pursue the filing or registration, or
support the continued prosecution or maintenance, of such Patent or Product
Trademark, as applicable, at its expense in such country. If such other Party
elects to pursue such filing or registration, as the case may be, or continue
such support, then such other Party shall notify such Party of such election and
such Party shall, and shall cause its Affiliates, licensees and sublicensees, as
applicable, to, (x) reasonably cooperate with such other Party in this regard,
and (y) subject to Article 3, promptly release or assign to such other Party,
without compensation, all right, title and interest in and to such Patent or
Product Trademark, as applicable, in such country.

        SECTION 7.3 ENFORCEMENT OF PATENTS AND TRADEMARKS.

                7.3.1 RIGHTS AND PROCEDURES. If Medarex or Northwest determines
that any Technology or Product Trademark is being infringed by a Third Party's
activities and that such infringement could affect the exercise by the Parties
of their respective rights and obligations under this Agreement, it shall
promptly notify the other Party in writing and provide such other Party with any
evidence of such infringement that is reasonably available. Promptly after the
receipt of such written notice, the Parties shall meet and discuss in good faith
the removal of such infringement. The pursuing Party shall consider in good
faith any comments from the other Party and shall keep the other Party
reasonably informed of any steps taken to remove such infringement.

                7.3.2 COLLABORATION TECHNOLOGY AND PRODUCT TRADEMARKS. With
respect to Collaboration Technology and Product Trademarks, the Steering
Committee shall have the first right to remove such infringement using
commercially appropriate steps, including the filing of an infringement suit or
taking other similar action. * incurred in connection with such action. In the
event the Steering Committee fails to take commercially appropriate steps to
remove any infringement of any such Collaboration Technology or Product
Trademark within ninety (90) days following notice of such infringement, or
earlier notifies the Parties in writing of its intent not to take such steps,
and (i) such failure to act is due to the refusal of one Party's representatives
on the Steering Committee to authorize action over the objection of the other
Party's representatives, then the Party whose representatives wish to proceed
shall have the right to do so at its expense, or (ii) such failure to act is due
to any reason other than as set forth in clause (i) above, then either Party
shall have the right to proceed at its expense; provided, however, that if the
Steering Committee has commenced negotiations with an alleged infringer for
discontinuance of such infringement within such ninety (90) day period, the
Steering Committee shall have an additional ninety (90) days to conclude its
negotiations before a Party unilaterally may bring suit for such infringement.

                7.3.3 OTHER TECHNOLOGY. With respect to Technology of a Party,
the owner of such Technology shall have the sole right, but not the obligation,
to remove such infringement; provided, however, that the other Party shall
reimburse the owner of such Technology for * of the reasonable out-of-pocket
costs incurred by such owner with respect to the removal of any such
infringement with respect to any Collaboration Product.

                                       25
<PAGE>   26

                7.3.4 COOPERATION. The Party not enforcing the applicable
Technology or Product Trademark shall provide reasonable assistance to the other
Party, including providing access to relevant documents and other evidence,
making its employees available at reasonable business hours, and joining the
action to the extent necessary to allow the enforcing Party to maintain the
action.

                7.3.5 RECOVERY. Any amounts recovered by a Party pursuant to
this Section 7.3, whether by settlement or judgment, shall be used to reimburse
the Parties for their reasonable costs and expenses in making such recovery
(which amounts shall be allocated pro rata if insufficient to cover the totality
of such expenses), with any remainder being retained by the Party that has
exercised its right to bring the enforcement action; provided, however, that to
the extent that any award is attributable to loss of sales of a Collaboration
Product, the Parties shall negotiate in good faith an appropriate allocation of
such award to reflect the economic interests of the Parties under this Agreement
with respect to such Collaboration Product.

        SECTION 7.4 POTENTIAL THIRD PARTY RIGHTS.

                7.4.1 THIRD PARTY LICENSES.

                        (a) If (i) in the Collective Opinion of Counsel, a
Party, or any of its Affiliates, licensees or permitted sublicensees, cannot
Exploit a Collaboration Product in a country in the Territory without infringing
one or more Patents that have issued to a Third Party in such country, or (ii)
as a result of any claim made against a Party, or any of its Affiliates,
licensees or permitted sublicensees, alleging that the Exploitation of a
Collaboration Product infringes or misappropriates any Patent or any other
intellectual property right of a Third Party in a country in the Territory, a
judgment is entered by a court of competent jurisdiction from which no appeal is
taken within the time permitted for appeal, such that a Party cannot Exploit
such Collaboration Product in such country without infringing the Patent or
other proprietary rights of such Third Party, then, in either case, the Parties
shall use Commercially Reasonable Efforts to obtain a license in the names of
the Parties from such Third Party as necessary for the Exploitation of any
Collaboration Products hereunder in such country. Such activities shall be
coordinated through the Steering Committee. Without acknowledging any actual or
potential infringement, the Parties agree that it is in the best interests of
the Collaboration to seek to enter into a cross license with * to ensure that
the Collaboration has freedom to operate with respect to Collaboration Products
against the Collaboration Target referred to on Appendix C as PSMA. Accordingly,
the Parties further agree that (i) no Collective Opinion of Counsel shall be
necessary for the Steering Committee to commence negotiations with * and its
licensees to obtain such cross license, and (ii) the Steering Committee shall,
promptly after the Effective Date, commence such negotiations and use
Commercially Reasonable Efforts to obtain such cross license.

                        (b) Notwithstanding subsection (a) above, Medarex shall
have the sole right to seek any such license with respect to Mice-Related
Technology or any Production Process Technology, and shall use Commercially
Reasonable Efforts to obtain such a license in its own name from such Third
Party in such country, under which Medarex shall, to the extent permissible
under such license, grant a sublicense to Northwest as necessary for Northwest,
and

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       26
<PAGE>   27

any of its Affiliates and permitted sublicensees, to Exploit the Collaboration
Products as provided hereunder in such country. If Medarex is unable to secure
the right to sublicense to Northwest, the Parties shall meet to discuss how to
proceed. If the Parties are unable to come to a mutually satisfactory
arrangement, and if Northwest does not wish to proceed with a joint development
and commercialization of a Collaboration Antibody for which such sublicense is
required, it shall notify Medarex thereof in writing, which notice shall be
deemed to be an Opt-Out Notice as provided in Section 5.1.1.

                        (c) The Parties shall * of any royalty or other payment
obligations under the licenses obtained as provided in subsections (a) or (b)
above, except with respect to the Medarex Technology or the Northwest
Technology, where Northwest and Medarex, respectively, shall be responsible for
* of only those royalty and other payment obligations with respect to the
Exploitation of Collaboration Products and the other activities of the Parties
hereunder.

                        (d) For purposes of this Section 7.4.1, "COLLECTIVE
OPINION OF COUNSEL" shall mean the final joint opinion of patent counsel
selected by Northwest and patent counsel selected by Medarex, after review of
all data and information reasonably available at the time such opinion is
rendered. If patent counsel for the Parties cannot agree on a final joint
opinion within twenty (20) days after submission of the matter to such counsel,
the patent counsel of the Parties shall agree on a third patent counsel who
shall offer an independent opinion on the subject matter, which independent
opinion shall be deemed the Collective Opinion of Counsel.

                7.4.2 THIRD PARTY LITIGATION.

                        (a) In the event that a Third Party institutes a Patent,
Trademark or other infringement suit (including any suit alleging the invalidity
or unenforceability of the Patents of a Party or its Affiliates, or claiming
confusion, deception or dilution of a Trademark by a Product Trademark) against
either Party or its respective Affiliates, licensees or permitted sublicensees
during the Term, alleging that the Exploitation of the Collaboration Products in
the Territory or any other activities hereunder, infringes one or more Patent,
Trademark or other intellectual property rights held by such Third Party (an
"INFRINGEMENT SUIT"), the Parties shall cooperate with one another in defending
such suit.

                        (b) With respect to the Medarex Technology or the
Northwest Technology, the Parties shall jointly direct and control any
Infringement Suit with respect to Collaboration Products or any Collaboration
Patents; provided, however, that no Party shall cease to defend, settle or
otherwise dispose of a suit with respect to any intellectual property of the
other Party without the prior written consent of such other Party.

                        (c) Each Party shall have the sole right to direct and
control (including the right to cease to defend, settle or compromise) any
Infringement Suit with respect to its Technology. The Parties * of any costs and
expenses of such defense, except with respect to the Medarex Technology or the
Northwest Technology, where Northwest and Medarex, respectively, shall be
responsible for * of those costs

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       27
<PAGE>   28

and expenses only with respect to the Exploitation of Collaboration Products and
the other activities of the Parties hereunder.

                7.4.3 RETAINED RIGHTS. Nothing in this Section 7.4 shall prevent
either Party, at its own expense, from obtaining any license or other rights
from Third Parties it deems appropriate in order to permit the full and
unhindered exercise of its rights or performance of its obligations under this
Agreement; provided, however, that the terms of such license shall not impair
the rights of the other Party to Exploit the Collaboration Products.

        SECTION 7.5 EXCHANGE OF KNOW-HOW.

                7.5.1 INFORMATION DISCLOSURE. Each Party shall, and shall cause
its Affiliates, licensees and sublicensees, as applicable, to, without
additional compensation and at such Party's sole expense, disclose and make
available to the other Party, in whatever form each such other Party may
reasonably request, all Regulatory Documentation, all of its other Know-How, all
Information and Inventions included in the Collaboration Technology and any
other Information and Inventions relating, directly or indirectly, to the
Exploitation of any Collaboration Products immediately after the Effective Date
and thereafter immediately upon the earlier of the conception or reduction to
practice, discovery, development or making of each such Regulatory
Documentation, Know-How, or other Information and Inventions.

                7.5.2 COOPERATION. With respect to the research, development,
commercialization or other Exploitation of the Collaboration Products, each
Party, shall cooperate with any and all reasonable requests for assistance from
the other Party, including by making its employees, consultants and other
scientific staff available upon reasonable notice during normal business hours
at their respective places of business to consult with such other Party, as
applicable, on issues arising during such research, development,
commercialization or Exploitation.

                7.5.3 BIOLOGICAL MATERIALS.

                        (a) For purposes of facilitating the conduct of the
research and development activities under this Agreement, Medarex and Northwest
shall each provide to the other tissues, cells, cell lines, organisms, blood
samples, genetic material, and other biological substances and materials,
including the Mice Materials, the Collaboration Targets and other Antigens
(collectively, "BIOLOGICAL MATERIALS") specified from time to time in this
Agreement or the applicable Project Plan. Each Party agrees to provide all such
Biological Materials to the other in accordance with this Agreement and the
applicable Project Plan, and under the supervision of the Steering Committee.

                        (b) The Parties agree that: (a) all Biological Materials
provided by one Party to the other Party and any Biological Material (including
Collaboration Products and other Mice Materials) produced against or with, or
derived from, such Biological Materials shall be used solely for the research
and development activities as provided in the Project Plan, and in material
compliance with all Applicable Law; (b) all such Biological Materials shall be
provided without any warranties, express or implied, (c) the Party providing
such Biological Materials

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<PAGE>   29

shall obtain (or cause its Third Party collaborators to obtain or certify that
they have obtained) all appropriate and required consents from the source of
such Biological Materials; (d) Biological Materials provided by one Party to the
other Party (other than Collaboration Products) shall not be made available by
such other Party to any Third Party except as expressly provided in the Project
Plan, unless the prior written consent of the Party providing such Biological
Materials is first obtained; and (e) subject to the license grants in Article 3
and other provisions in this Agreement, all right, title and interest in and to
(i) the Mice Materials and the Mice-Related Technology shall be, and remain,
vested in Medarex, and (ii) the Collaboration Targets shall be, and remain,
vested in Northwest.

                7.5.4 REGULATORY RECORDS. With respect to the subject matter of
this Agreement, each Party shall maintain, or cause to be maintained, records of
its respective research, development, manufacturing and commercialization
activities, including all Regulatory Documentation, in sufficient detail and in
good scientific manner appropriate for patent and regulatory purposes, which
shall be complete and accurate and shall fully and properly reflect all work
done and results achieved in the performance of such activities, and which shall
be retained during the term of this Agreement and for a period of five (5) years
thereafter, or for such longer period as may be required by Applicable Law. Each
Party shall have the right, during normal business hours and upon reasonable
notice, to inspect and copy any such records, except, with respect to Medarex's
records, to the extent that such records contain proprietary information with
respect to the Production Process Technology or the HuMAb Mice.

                7.5.5 PRODUCTION PROCESS TECHNOLOGY. Notwithstanding anything to
the contrary in this Section 7.5 or elsewhere in this Agreement, Medarex shall
not be obligated to disclose or provide any of its Production Process
Technology, including Biological Materials, to Northwest or any Third Party;
provided, however, that Medarex shall provide such Production Process Know-How
to the Regulatory Authorities as is necessary to obtain and maintain Regulatory
Approval for Collaboration Products supplied by it pursuant to Section 1.6.
Medarex shall have the right to provide such Know-How to the Regulatory
Authorities in a drug master file, or any foreign equivalent that is designed to
protect Medarex's Confidential Information.

                                    ARTICLE 8
                              TERM AND TERMINATION

        SECTION 8.1 TERM. The term of this Agreement (the "Term") shall commence
upon the Effective Date and shall continue in effect until the later of (a) the
first anniversary of the completion of all of the activities in Section 1.2, or
(b) such time as there is no longer any Collaboration Product being Exploited
hereunder, whether pursuant to Section 1.7 or otherwise, or any Unilateral
Product being Exploited under a Unilateral Development and Commercialization
Agreement, unless terminated at an earlier date in accordance with the terms and
conditions set forth in this Article 8.

        SECTION 8.2 TERMINATION FOR MATERIAL BREACH.

                8.2.1 Any material failure by a Party to comply with any of its
material obligations contained herein shall entitle the Party not in default to
give to the Party in default

                                       29
<PAGE>   30

written notice specifying the nature of the default, requiring the defaulting
Party to make good or other-wise cure such default, and stating its intention if
such default is not cured to terminate or, at the option of the Party not in
default, to convert a Collaboration Product to which the material breach applies
to a Unilateral Product pursuant to Section 5.1.

                8.2.2 If such default is not cured within thirty (30) days after
the receipt of notice pursuant to subsection 8.2.1 above (or, if such default
cannot be cured within such thirty (30)-day period, if the Party in default does
not commence actions to cure such default within such period and thereafter
diligently continue such actions or if such default is not otherwise cured
within one-hundred and eighty (180) days after the receipt of such notice),
except in the case of a payment default, as to which the defaulting Party shall
have only a thirty (30) day cure period, the Party not in default shall be
entitled, on written notice to the other Party, without prejudice to any of its
other rights conferred on it by this Agreement, and in addition to any other
remedies available to it by law or in equity, to (a) terminate this Agreement in
its entirety, or (b) convert such Collaboration Product to a Unilateral Product
pursuant to Section 5.1, whereupon the defaulting Party shall be deemed the
Opting-Out Party with respect to such Unilateral Product for all purposes
hereunder and the notice provided under this provision shall be deemed
equivalent to an Election Notice as provided in Section 5.1.

        SECTION 8.3 TERMINATION UPON INSOLVENCY. Either Party may terminate this
Agreement if, at any time, the other Party shall file in any court or agency
pursuant to any statute or regulation of any state, country or jurisdiction, a
petition in bankruptcy or insolvency or for reorganization or for an arrangement
or for the appointment of a receiver or trustee of that Party or of its assets,
or if such other Party proposes a written agreement of composition or extension
of its debts, or if such other Party shall be served with an involuntary
petition against it, filed in any insolvency proceeding, and such petition shall
not be dismissed within sixty (60) days after the filing thereof, or if such
other Party shall propose or be a party to any dissolution or liquidation, or if
such other Party shall make an assignment for the benefit of its creditors.

        SECTION 8.4 RIGHTS IN BANKRUPTCY. All rights and licenses granted under
or pursuant to this Agreement by Medarex or Northwest are, and shall otherwise
be deemed to be, for purposes of Section 365(n) of the United States Bankruptcy
Code, licenses of rights to "intellectual property" as defined under Section 101
of the United States Bankruptcy Code. The Parties agree that the Parties, as
licensees of such rights under this Agreement, shall retain and may fully
exercise all of their rights and elections under the United States Bankruptcy
Code. The Parties further agree that, in the event of the commencement of a
bankruptcy proceeding by or against a Party under the United States Bankruptcy
Code, the Party hereto that is not a Party to such proceeding 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, which,
if not already in the non-subject Party's possession, shall be promptly
delivered to it (a) upon any such commencement of a bankruptcy proceeding upon
the non-subject Party's written request therefor, unless the Party subject to
such proceeding continues to perform all of its obligations under this Agreement
or (b) if not delivered under clause (a) above, following the rejection of this
Agreement by or on behalf of the Party subject to such proceeding upon written
request therefor by the non-subject Party.

                                       30
<PAGE>   31

        SECTION 8.5 CONSEQUENCES OF EXPIRATION OR TERMINATION.

                8.5.1 LICENSES. Upon expiration of the full term of this
Agreement in accordance with Section 8.1 and payment of all amounts owed
pursuant to Section 4.1, the licenses granted by Medarex to Northwest, and by
Northwest to Medarex, hereunder shall be deemed fully-paid up.

                8.5.2 RETURN OF INFORMATION AND MATERIALS. Upon expiration of
this Agreement pursuant to Section 8.1 or upon termination of this Agreement in
its entirety by either Party pursuant to this Article 8, each Party, at the
request of the other Party, shall return Biological Materials of such other
Party and all data, files, records and other materials in its possession or
control relating to such other Party's Technology, or containing or comprising
such other Party's Information and Inventions or other Confidential Information
(as defined in Article 6) and, in each case, to which the returning Party does
not retain rights hereunder (except one copy of which (other than Biological
Materials) may be retained solely for archival purposes).

        SECTION 8.6 ACCRUED RIGHTS; SURVIVING OBLIGATIONS.

                8.6.1 ACCRUED RIGHTS. Termination or expiration of this
Agreement for any reason shall be without prejudice to any rights that shall
have accrued to the benefit of a Party prior to such termination or expiration.
Such termination or expiration shall not relieve a Party from obligations that
are expressly indicated to survive the termination or expiration of this
Agreement.

                8.6.2 SURVIVAL. Articles 4(with respect to obligations arising
prior to expiration or termination), 6 and 9, and Sections 2.3, 3.3.5, 3.4, 7.1,
7.2, 7.5.3, 7.5,4, 7.5.5, 8.5, 11.5 and 11.6 of this Agreement and this Section
8.6 shall survive expiration or termination of this Agreement for any reason.

                                    ARTICLE 9
                          INDEMNIFICATION AND INSURANCE

        SECTION 9.1 INDEMNIFICATION OF MEDAREX. Northwest shall indemnify
Medarex and its Affiliates, and their respective directors, officers, employees
and agents, and defend and save each of them harmless, from and against any and
all losses, damages, liabilities, costs and expenses (including reasonable
attorneys' fees and expenses) in connection with any and all liability suits,
investigations, claims or demands (collectively, "LOSSES") arising from or
occurring as a result of or in connection with (a) any breach by Northwest of
this Agreement, or (b) the gross negligence or willful misconduct on the part of
Northwest or its Affiliates, licensees or sublicensees in performing any
activity contemplated by this Agreement, except for those Losses for which
Medarex has an obligation to indemnify Northwest pursuant to Section 9.2, as to
which Losses each Party shall indemnify the other to the extent of their
respective liability for the Losses.

                                       31
<PAGE>   32

        SECTION 9.2 INDEMNIFICATION OF NORTHWEST. Medarex: shall indemnify
Northwest, its Affiliates, and their respective directors, officers, employees
and agents, and defend and save each of them harmless, from and against any and
all Losses arising from or occurring as a result of or in connection with (a)
any breach by Medarex of this Agreement, or (b) the gross negligence or willful
misconduct on the part of Medarex or its Affiliates, licensees or sublicensees
in performing any activity contemplated by this Agreement, except for those
Losses for which Northwest has an obligation to indemnify Medarex: and its
Affiliates pursuant to Section 9.1, as to which Losses each Party shall
indemnify the other to the extent of their respective liability for the Losses.

        SECTION 9.3 INDEMNIFICATION PROCEDURE.

                9.3.1 NOTICE OF CLAIM. The indemnified Party shall give the
indemnifying Party prompt written notice (an "INDEMNIFICATION CLAIM NOTICE") of
any Losses or discovery of fact upon which such indemnified Party intends to
base a request for indemnification under Section 9.1 or Section 9.2, but in no
event shall the indemnifying Party be liable for any Losses that result from any
delay in providing such notice. Each Indemnification Claim Notice must contain a
description of the claim and the nature and amount of such Loss (to the extent
that the nature and amount of such Loss are known at such time). The indemnified
Party shall furnish promptly to the indemnifying Party copies of all papers and
official documents received in respect of any Losses. All indemnification claims
in respect of a Party, its Affiliates or their respective directors, officers,
employees and agents (collectively, the "INDEMNITEES" and each an "INDEMNITEE")
shall be made solely by such Party to this Agreement (the "INDEMNIFIED PARTY").

                9.3.2 THIRD PARTY CLAIMS. The obligations of an indemnifying
Party under this Article 9 with respect to Losses arising from claims of any
Third Party that are subject to indemnification as provided for in Section 9.1
or 9.2 (a "THIRD PARTY CLAIM") shall be governed by and be contingent upon the
following additional terms and conditions:

                        (a) CONTROL OF DEFENSE.

                                (i) At its option, the indemnifying Party may
assume the defense of any Third Party Claim by giving written notice to the
Indemnified Party within thirty (30) days after the indemnifying Party's receipt
of an Indemnification Claim Notice. The assumption of the defense of a Third
Party Claim by the indemnifying Party shall not be construed as an
acknowledgment that the indemnifying Party is liable to indemnify any Indemnitee
in respect of the Third Party Claim, nor shall it constitute a waiver by the
indemnifying Party of any defenses it may assert against any Indemnitee's claim
for indemnification,

                                (ii) Upon assuming the defense of a Third Party
Claim, the indemnifying Party may appoint as lead counsel in the defense of the
Third Party Claim any legal counsel selected by the indemnifying Party. In the
event the indemnifying Party assumes the defense of a Third Party Claim, the
Indemnified Party shall immediately deliver to the indemnifying Party all
original notices and documents (including court papers) received by any
Indemnitee in connection with the Third Party Claim. Should the indemnifying
Party assume the

                                       32
<PAGE>   33

defense of a Third Party Claim, the indemnifying Party shall not be liable to
the Indemnified Party or any other Indemnitee for any legal expenses
subsequently incurred by such Indemnified Party or other Indemnitee in
connection with the analysis, defense or settlement of the Third Party Claim.

                                (iii) In the event that it is ultimately
determined that the indemnifying Party is not obligated to indemnify, defend or
hold harmless an Indemnitee from and against the Third Party Claim, the
Indemnified Party shall reimburse the indemnifying Party for any and all costs
and expenses (including attorneys' fees and costs of suit) and any Losses
incurred by the indemnifying Party in its defense of the Third Party Claim with
respect to such Indemnitee.

                        (b) RIGHT TO PARTICIPATE IN DEFENSE. Without limiting
Section 9.3.2(a), any Indemnitee shall be entitled to participate in, but not
control, the defense of such Third Party Claim and to employ counsel of its
choice for such purpose- provided, however that such employment shall be at the
Indemnitee's own expense unless (i) the employment thereof has been specifically
authorized by the indemnifying Party in writing, or (ii) the indemnifying Party
has failed to assume the defense and employ counsel in accordance with Section
9.3.2(a) (in which case the Indemnified Party shall control the defense).

                        (c) SETTLEMENT. With respect to any Losses relating
solely to the payment of money damages in connection with a Third Party Claim
and that will not result in the Indemnitee's becoming subject to injunctive or
other relief or otherwise adversely affect the business of the Indemnitee in any
manner, and as to which the indemnifying Party shall have acknowledged in
writing the obligation to indemnify the Indemnitee hereunder, the indemnifying
Party shall have the sole right to consent to the entry of any judgment, enter
into any settlement or otherwise dispose of such Loss, on such terms as the
indemnifying Party, in its sole discretion, shall deem appropriate. With respect
to all other Losses in connection with Third Party Claims, where the
indemnifying Party has assumed the defense of the Third Party Claim in
accordance with Section 9.3.2(a), the indemnifying Party shall have authority to
consent to the entry of any judgment, enter into any settlement or otherwise
dispose of such Loss provided it obtains the prior written consent of the
Indemnified Party (which consent shall not be unreasonably withheld or delayed).
The indemnifying Party shall not be liable for any settlement or other
disposition of a Loss by an Indemnitee that is reached without the written
consent of the indemnifying Party. Regardless of whether the indemnifying Party
chooses to defend or prosecute any Third Party Claim, no Indemnitee shall admit
any liability with respect to, or settle, compromise or discharge, any Third
Party Claim without the prior written consent of the indemnifying Party.

                        (d) COOPERATION. Regardless of whether the indemnifying
Party chooses to defend or prosecute any Third Party Claim, the Indemnified
Party shall, and shall cause each other Indemnitee to, cooperate in the defense
or prosecution thereof and shall furnish such records, information and
testimony, provide such witnesses and attend such conferences, discovery
proceedings, hearings, trials and appeals as may be reasonably requested in
connection therewith. Such cooperation shall include access during normal
business hours afforded to the indemnifying Party to, and reasonable retention
by the Indemnified Party of, records and information that are reasonably
relevant to such Third Party Claim, and making Indemnitees and

                                       33
<PAGE>   34

other employees and agents available on a mutually convenient basis to provide
additional information and explanation of any material provided hereunder, and
the indemnifying Party shall reimburse the Indemnified Party for all its
reasonable out-of-pocket expenses in connection therewith.

                        (e) EXPENSES. Except as provided above, the reasonable
and verifiable costs and expenses, including fees and disbursements of counsel,
incurred by the Indemnified Party in connection with any claim shall be
reimbursed on a calendar quarter basis by the indemnifying Party, without
prejudice to the indemnifying Party's right to contest the Indemnified Party's
right to indemnification and subject to refund in the event the indemnifying
Party is ultimately held not to be obligated to indemnify the Indemnified Party.

        SECTION 9.4 INSURANCE. Each Party shall have and maintain such types and
amounts of liability insurance as is normal and customary in the industry
generally for parties similarly situated, and shall upon request provide the
other Party with a copy of its policies of insurance in that regard, along with
any amendments and revisions thereto.

                                   ARTICLE 10
                         REPRESENTATIONS AND WARRANTIES

        SECTION 10.1 REPRESENTATIONS, WARRANTIES AND COVENANTS. Each Party
hereby represents, warrants and covenants to the other Party as of the Effective
Date as follows:

                10.1.1 CORPORATE AUTHORITY. Such Party (a) has the power and
authority and the legal right to enter into this Agreement and perform its
obligations hereunder, and (b) has taken all necessary action on its part
required to authorize the execution and delivery of this Agreement and the
performance of its obligations hereunder. This Agreement has been duly executed
and delivered on behalf of such Party and constitutes a legal, valid and binding
obligation of such Party and is enforceable against it in accordance with its
terms subject to the effects of bankruptcy, insolvency or other laws of general
application affecting the enforcement of creditor rights and judicial principles
affecting the availability of specific performance and general principles of
equity, whether enforceability is considered a proceeding at law or equity.

                10.1.2 LITIGATION. Such Party is not aware of any pending or
threatened litigation (and has not received any communication) that alleges that
such Party's activities related to this Agreement have violated, or that by
conducting the activities as contemplated herein such Party would violate, any
of the intellectual property rights of any other party.

                10.1.3 CONSENTS, APPROVALS, ETC. All necessary consents,
approvals and authorizations of all Regulatory Authorities and other parties
required to be obtained by such Party in connection with the execution and
delivery of this Agreement and the performance of its obligations hereunder have
been obtained.

                10.1.4 CONFLICTS. The execution and delivery of this Agreement
and the performance of such Party's obligations hereunder (a) do not conflict
with or violate any requirement of Applicable Law or any provision of the
articles of incorporation, bylaws or any

                                       34
<PAGE>   35

similar instrument of such Party, as applicable, in any material way, and (b) do
not conflict with, violate, or breach or constitute a default or require any
consent under, any contractual obligation or court or administrative order by
which such Party is bound.

                10.1.5 DEBARMENT. No such Party nor any of its Affiliates has
been debarred or is subject to debarment and neither such Party nor any of its
Affiliates will use in any capacity, in connection with the services to be
performed under this Agreement, any party who has been debarred pursuant to
Section 306 of the Federal Food, Drug, and Cosmetic Act, as amended, or who is
the subject of a conviction described in such section. Each Party will inform
the other Party in writing immediately if it or any party who is performing
services hereunder is debarred or is the subject of a conviction described in
Section 306, or if any action, suit, claim, investigation or legal or
administrative proceeding is pending or, to such Party's knowledge, is
threatened, relating to the debarment or conviction of such Party or any party
performing services hereunder.

        SECTION 10.2 ADDITIONAL REPRESENTATIONS AND WARRANTIES OF MEDAREX.

                10.2.1 Medarex represents and warrants to Northwest that Medarex
is a corporation duly organized, validly existing and in good standing under the
laws of the State of New Jersey, and has full corporate power and authority and
the legal right to own and operate its property and assets and to carry on its
business as it is now being conducted and as it is contemplated to be conducted
by this Agreement.

                10.2.2 Except as set forth in Appendix E on Schedule 10.2
attached hereto, to the knowledge of the officers of Medarex and without a duty
to conduct any investigation, as of the Effective Date, there are no existing or
threatened (in writing) actions, suits or claims pending with respect to the
Medarex Technology.

                10.2.3 To the knowledge of the officers of Medarex, there are no
issued U.S., EPO or Japanese patents owned by third parties (other than those
Controlled by Medarex) that would be infringed by the use of the Mice Materials
and/or Medarex Technology by Medarex to elicit, produce in hybridornas and/or
identify human monoclonal antibodies in connection with the licenses granted
herein; provided, however, that the representation and warranty set forth in
this clause does not include any patents or patent applications that cover (A)
the targets of such human monoclonal antibodies or (B) the human monoclonal
antibodies specific to such targets or (C) the use of such human monoclonal
antibodies.

        SECTION 10.3 ADDITIONAL REPRESENTATIONS AND WARRANTIES OF NORTHWEST.

                10.3.1 Northwest represents and warrants to Medarex that
Northwest is a corporation duly organized, validly existing and in good standing
under the laws of Delaware, and has full corporate power and authority and the
legal right to own and operate its property and assets and to carry on its
business as it is now being conducted and as it is contemplated to be conducted
by this Agreement.

                                       35
<PAGE>   36

                10.3.2 Except as set forth in Appendix E on Schedule 10.3
attached hereto, to the knowledge of the officers of Northwest and without a
duty to conduct any investigation, as of the Effective Date, there are no
existing or threatened (in writing) actions, suits or claims pending with
respect to the Northwest Technology.

                10.3.3 To the knowledge of the officers of Northwest, there are
no issued U.S., EPO or Japanese patents owned by third parties (other than those
Controlled by Northwest) that would be infringed by the use of the Collaboration
Targets or the human monoclonal antibodies specific to such targets in
connection with the licenses granted herein.

        SECTION 10.4 KNOWLEDGE; OFFICERS. For purposes of Sections 10.1, 10.2
and 10.3, (a) "knowledge of' a Party shall mean such Party's good faith
understanding of the facts and information in its possession without any duty to
conduct any investigation with respect to such facts and information, and (b)
"officers" of a Party shall mean persons in the positions of vice president,
senior vice president, executive vice president, president and chief executive
officer.

        SECTION 10.5 DISCLAIMER OF WARRANTY. EXCEPT FOR THE EXPRESS WARRANTIES
SET FORTH IN SECTIONS 10.1, 10.2 AND 10.3, NORTHWEST AND MEDAREX MAKE NO
REPRESENTATIONS AND GRANT NO WARRANTIES, EXPRESS OR IMPLIED, EITHER IN FACT OR
BY OPERATION OF LAW, BY STATUTE OR OTHERWISE, AND NORTHWEST AND MEDAREX EACH
SPECIFICALLY DISCLAIM ANY OTHER WARRANTIES, WHETHER WRITTEN OR ORAL, OR EXPRESS
OR IMPLIED, INCLUDING ANY WARRANTY OF QUALITY, MERCHANTABILITY OR FITNESS FOR A
PARTICULAR USE OR PURPOSE OR ANY WARRANTY AS TO THE VALIDITY OF ANY PATENTS OR
THE NON-INFRINGEMENT OF ANY INTELLECTUAL PROPERTY RIGHTS OF THIRD PARTIES.

                                   ARTICLE 11
                                  MISCELLANEOUS

        SECTION 11.1 FORCE MAJEURE. Neither Party shall be held liable or
responsible to the other Party or be deemed to have defaulted under or breached
this Agreement for failure or delay in fulfilling or performing any term of this
Agreement when such failure or delay is caused by or results from events beyond
the reasonable control of the non-performing Party, including fires, floods,
embargoes, shortages, epidemics, quarantines, war, acts of war (whether war be
declared or not), insurrections, riots, civil commotion, strikes, lockouts or
other labor disturbances, acts of God or acts, omissions or delays in acting by
any governmental authority. The non-performing Party shall notify the other
Party of such force majeure within ten (10) days after such occurrence by giving
written notice to the other Party stating the nature of the event, its
anticipated duration, and any action being taken to avoid or minimize its
effect. The suspension of performance shall be of no greater scope and no longer
duration than is necessary and the non-performing Party shall use Commercially
Reasonable Efforts to remedy its inability to perform; provided, however, that
in the event the suspension of performance continues for one-hundred and eighty
(180) days after the date of the occurrence, the Parties shall meet to discuss
in good faith how to proceed in order to accomplish the goals of the
Collaboration outlined in this Agreement.

                                       36
<PAGE>   37
        SECTION 11.2 SUBCONTRACTORS. Each Party shall have the right, subject to
the prior written consent of the Steering Committee, such consent not to be
unreasonably withheld or delayed, to subcontract any of its research,
development, manufacture and/or commercialization activities to a Third Party,
provided that it furnishes the other Party with advanced written notice thereof,
which notice shall specify the work to be subcontracted, and obtains a written
undertaking from the subcontractor that it shall be subject to the applicable
terms and conditions of this Agreement, including the provisions of Article 6.
If a Party wishes to subcontract any of its research, development, manufacturing
or commercialization activities to a Third Party and the Steering Committee
consents, the other Party may submit a bid to the subcontracting Party to
perform such work. The subcontracting Party shall use Commercially Reasonable
Efforts to enter into an agreement with the bidder that is best able to meet the
Collaboration's requirements, taking into consideration such factors as price,
quality, capacity, quantity, reliability and reputation, provided that such
bidder is reasonably acceptable to the Steering Committee. Unless the Project
Plan provides, or the Steering Committee agrees otherwise, the Parties shall *
in the costs and expenses associated with the use of a subcontractor to conduct
research, development, manufacture and commercialization activities, but unless
the Parties agree otherwise, the subcontracting Party shall remain solely liable
for the performance of its research, development, manufacture or
commercialization activities by its subcontractor; provided, however, that
Northwest and Medarex each shall remain solely responsible for all costs and
expenses associated with its-use of subcontractor(s) with respect to the
Northwest Research Activities and the Medarex Research Activities, respectively.

        SECTION 11.3 ASSIGNMENT. Without the prior written consent of the other
Party hereto, neither Party shall sell, transfer, assign, delegate, pledge or
otherwise dispose of, whether voluntarily, involuntarily, by operation of law or
otherwise, this Agreement or any of its rights or duties hereunder; provided,
however that either Party hereto may assign or transfer this Agreement or any of
its rights or obligations hereunder without the consent of the other Party (a)
to any Affiliate of such Party; or (b) to any Third Party with which it may
merge or consolidate, or to which it may transfer all or substantially all of
its assets to which this Agreement relates if in any such event (i) the
assigning Party (provided that it is not the surviving entity) remains jointly
and severally liable with the relevant Northwest Affiliate, Medarex Affiliate or
Third Party assignee under this Agreement, and (ii) the relevant Northwest
Affiliate assignee, Medarex Affiliate assignee, Third Party assignee or
surviving entity assumes in writing all of the assigning Party's obligations
under this Agreement. Any purported assignment or transfer in violation of this
Section shall be void ab initio and of no force or effect.

        SECTION 11.4 SEVERABILITY. If any provision of this Agreement is held to
be illegal, invalid or unenforceable under any present or future law, and if the
rights or obligations of either Party under this Agreement will not be
materially and adversely affected thereby, (a) such provision shall be fully
severable, (b) this Agreement shall be construed and enforced as if such
illegal, invalid or unenforceable provision had never comprised a part hereof,
(c) the remaining provisions of this Agreement shall remain in full force and
effect and shall not be affected by the illegal, invalid or unenforceable
provision or by its severance herefrom, and (d) in lieu of such illegal, invalid
or unenforceable provision, there shall be added automatically as a part of this
Agreement a legal, valid and enforceable provision as similar in terms to such
illegal, invalid or

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       37
<PAGE>   38

unenforceable provision as may be possible and reasonably acceptable to the
Parties herein. To the fullest extent permitted by applicable law, each Party
hereby waives any provision of law that would render any provision prohibited or
unenforceable in any respect.

        SECTION 11.5 GOVERNING LAW, JURISDICTION, VENUE AND SERVICE. This
Agreement shall be governed by and construed in accordance with the laws of the
State of New York, applicable to contracts made and wholly performed within such
jurisdiction by residents of such jurisdiction. Subject to Section 2.3, the
Parties hereby irrevocably and unconditionally consent to the exclusive
jurisdiction of the courts of the State of New York and the United States
District Court for the Southern District of New York for any action, suit or
proceeding (other than appeals therefrom) arising out of or relating to this
Agreement, and agree not to commence any action, suit or proceeding (other than
appeals therefrom) related thereto except in such courts. The Parties further
hereby irrevocably and unconditionally waive any objection to the laying of
venue of any action, suit or proceeding (other than appeals therefrom) arising
out of or relating to this Agreement in the courts of the State of New York or
the United States District Court for the Southern District of New York, and
hereby further irrevocably and unconditionally waive and agree not to plead or
claim In any such court that any such action, suit or proceeding brought in any
such court has been brought in an inconvenient forum. Each Party hereto further
agrees that service of any process, summons, notice or document by U.S.
registered mail to its address set forth below shall be effective service of
process for any, action, suit or proceeding brought against it under this
Agreement in any such court.

        SECTION 11.6 NOTICES. All notices or other communications that are
required or permitted hereunder shall be in writing and delivered personally,
sent by facsimile (and promptly confirmed by personal delivery, registered or
certified mail or overnight courier as provided herein), sent by
nationally-recognized overnight courier or sent by registered or certified mail,
postage prepaid, return receipt requested, addressed as follows:

        If to Northwest, to:

               Northwest Biotherapeutics, Inc.
               21720 23rd Dr. SE, Suite 100
               Bothell, Washington 98021
               Attention:  President
               Facsimile- (425) 608-3026

        with a copy to:

               Lane Powell Spears Lubersky LLP
               1420 Fifth Avenue Suite 4100
               Seattle, WA 98101-2338
               Attention:  Jim Johnston, Esq.
               Facsimile:  (206) 223-7107

                                       38
<PAGE>   39

        If to Medarex, to:

               Medarex, Inc.
               707 State Road, Suite 206
               Princeton, New Jersey 08540-1437
               Attention:  President
               Facsimile:  (609) 430-2850

        with a copy to:

               Medarex, Inc.
               707 State Road, Suite 206
               Princeton, New Jersey 08540-1437
               Attention:  General Counsel
               Facsimile:  (609) 430-2850

or to such other address as the Party to whom notice is to be given may have
furnished to the other Party in writing in accordance herewith. Any such
communication shall be deemed to have been given (i) when delivered, if
personally delivered or sent by facsimile on a business day, (ii) on the
business day after dispatch, if sent by nationally-recognized overnight courier,
and (iii) on the third business day following the date of mailing, if sent by
mail. It is understood and agreed that this Section 11.6 is not intended to
govern the day-to-day business communications necessary between the Parties in
performing their duties, in due course, under the terms of this Agreement.

        SECTION 11.7 ENTIRE AGREEMENT; MODIFICATIONS. This Agreement sets forth
and constitutes the entire agreement and understanding between the Parties with
respect to the subject matter hereof and all prior agreements, understanding,
promises and representations, whether written or oral, with respect thereto are
superseded hereby. Each Party confirms that it is not relying on any
representations or warranties of the other Party except as specifically set
forth herein. No amendment, modification, release or discharge shall be binding
upon the Parties unless in writing and duly executed by authorized
representatives of both Parties.

        SECTION 11.8 RELATIONSHIP OF THE PARTIES. It is expressly agreed that
the Parties shall be independent contractors of one another and that the
relationship between the Parties shall not constitute a partnership, joint
venture or agency. Neither Party shall have the authority to make any
statements, representations or commitments of any kind, or to take any action,
which shall be binding on the other, without the prior written consent of the
other to do so. All persons employed by a Party shall be employees of such Party
and not of the other Party and all costs and obligations incurred by reason of
any such employment shall be for the account and expense of such Party.

        SECTION 11.9 WAIVER. Any term or condition of this Agreement may be
waived at any time by the Party that is entitled to the benefit thereof, but no
such waiver shall be effective unless set forth in a written instrument duly
executed by or on behalf of the Party waiving such term or condition. The waiver
by either Party hereto of any right hereunder or of the failure to

                                       39
<PAGE>   40

perform or of a breach by the other Party shall not be deemed a waiver of any
other right hereunder or of any other breach or failure by said other Party
whether of a similar nature or otherwise.

        SECTION 11.10 COUNTERPARTS. This Agreement may be executed in two (2) or
more counterparts, each of which shall be deemed an original, but all of which
together shall constitute one and the same instrument.

        SECTION 11.11 NO BENEFIT TO THIRD PARTIES. The representations,
warranties, covenants and agreements set forth in this Agreement are for the
sole benefit of the Parties hereto and their successors and permitted assigns,
and they shall not be construed as conferring any rights on any other parties.

        SECTION 11.12 FURTHER ASSURANCE. Each Party shall duly execute and
deliver, or cause to be duly executed and delivered, such further instruments
and do and cause to be done such further acts and things, including the filing
of such assignments, agreements, documents and instruments, as may be necessary
or as the other Party may reasonably request in connection with this Agreement
or to carry out more effectively the provisions and purposes, or to better
assure and confirm unto such other Party its rights and remedies under this
Agreement.

        SECTION 11.13 ENGLISH LANGUAGE. This Agreement has been written and
executed in the English language. Any translation into any other language shall
not be an official version thereof, and in the event of any conflict in
interpretation between the English version and such translation, the English
version shall control.

        SECTION 11.14 REFERENCES. Unless otherwise specified, (a) references in
this Agreement to any Article, Section, Schedule or Exhibit shall mean
references to such Article, Section, Schedule or Exhibit of this Agreement, (b)
references in any section to any clause are references to such clause of such
section, and (c) references to any agreement, instrument or other document in
this Agreement refer to such agreement, instrument or other document as
originally executed or, if subsequently varied, replaced or supplemented from
time to time, as so varied, replaced or supplemented and in effect at the
relevant time of reference thereto.

        SECTION 11.15 CONSTRUCTION. Except where the context otherwise requires,
wherever used, the singular shall include the plural, the plural the singular,
the use of any gender shall be applicable to all genders and the word "or" is
used in the inclusive sense (and/or). The captions of this Agreement are for
convenience of reference only and in no way define, describe, extend or limit
the scope or intent of this Agreement or the intent of any provision contained
in this Agreement. The term "including" as used herein shall mean including,
without limiting the generality of any description preceding such term. The
language of this Agreement shall be deemed to be the language mutually chosen by
the Parties and no rule of strict construction shall be applied against either
Party hereto.

              [Remainder of this page is left blank intentionally]

                                       40
<PAGE>   41

        IN WITNESS WHEREOF, the Parties hereto have caused this Agreement to be
executed by their duly authorized representatives as of the date first above
written,

MEDAREX, INC.                               NORTHWEST BIOTHERAPEUTICS, INC.

By:                                         By:
   ---------------------------------           ---------------------------------

Name:  Donald L. Drakeman                   Name:
     -------------------------------             -------------------------------

Title:  President and CEO                   Title:
                                                  ------------------------------

                                       41
<PAGE>   42

                                   APPENDIX A

                                   DEFINITIONS

        This Appendix to the COLLABORATION AGREEMENT ("AGREEMENT") effective as
of April 24, 2001, by and between Northwest, INC. ("NORTHWEST") and MEDAREX,
INC., on behalf of itself and its wholly owned subsidiary, GENPHARM
INTERNATIONAL, INC., (collectively, "MEDAREX") provides agreed upon definitions
applicable to the Parties for purposes of the Agreement. All capitalized terms
used herein without definition shall have the meanings ascribed thereto in the
Agreement, unless otherwise expressly provided herein.

        The contents of this Appendix A are hereby incorporated into the
Agreement and are governed by the terms and conditions of the Agreement,
including the confidentiality provisions set forth therein.

        "AFFILIATE" of a party shall mean any other party that, directly or
indirectly, through one or more intermediaries, controls, is controlled by, or
is under common control with such first party. For purposes of this definition
only, "control" and, with correlative meanings, the terms "controlled by" and
"under common control with" shall mean (a) the possession, directly or
indirectly, of the power to direct the management or policies of a party,
whether through the ownership of voting securities or by contract relating to
voting rights or corporate governance, or (b) the ownership, directly or
indirectly, of more than fifty percent (50%) of the voting securities or other
ownership interest of a party; provided that, if local law restricts foreign
ownership, control will be established by direct or indirect ownership of the
maximum ownership percentage that may, under such local law, be owned by foreign
interests.

        "ANTIBODY" shall mean any fully human monoclonal antibody, or fragment
thereof, with a * that has a * for an Antigen. References in the Agreement to an
"Antibody" shall include (a) * with respect to the * of such Antibody, and (b) *
with respect to the * of such Antibody (or a * of such * containing that portion
of such * ). By way of clarification, Antibodies with * shall be deemed to be
different Antibodies, irrespective of whether they bind to the same Antigen.

        "ANTIBODY PRODUCT" shall mean any composition or formulation containing
or comprising one or more Antibodies, including, by way of clarification, (a) *
one or more of such * with respect to the * of such Antibodies, and (b) * with
respect to the * of such Antibodies (or a * of such * containing that portion of
such * , for the diagnosis, prophylaxis or treatment of human diseases or
conditions.

        "ANTIGEN" shall mean any protein (including any glyco- or lipo-protein),
carbohydrate, compound or other composition, and any fragment, peptide or
epitope thereof, that stimulates the production of antibodies.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       42
<PAGE>   43

        "APPLICABLE LAW" shall mean the applicable laws, rules, and regulations,
including any rules, regulations, guidelines, or other requirements of the
Regulatory Authorities, that may be in effect from time to time in the
Territory,

        "BIOSITE AGREEMENT" shall mean that certain Collaboration Agreement,
dated as of June 1, 2000, between Medarex and Biosite Diagnostics Incorporated,
a Delaware corporation.

        "BLA" or "BIOLOGICS LICENSE APPLICATION" shall mean a Biologics License
Application, as defined in the U.S. Federal Food, Drug, and Cosmetics Act, as
amended, and the regulations promulgated thereunder, and any corresponding
foreign or domestic marketing authorization application, registration or
certification, necessary or reasonably useful to market a Collaboration Product
in the Territory, but not including pricing and reimbursement approvals.

        "COLLABORATION PRODUCT" shall mean any Antibody Product that contains a
Collaboration Antibody.

        "COLLABORATION TARGET" shall mean any Antigen listed on Appendix C, as
such appendix may be amended pursuant to this Agreement.

        "COLLABORATION TECHNOLOGY" shall mean any and all (a) Information and
Inventions, conceived, discovered, developed or otherwise made, as necessary to
establish authorship, inventorship or ownership under Applicable Law, by or on
behalf of a Party or its Affiliates or, to the extent permitted, its
sublicensees (whether alone or jointly), in connection with the work conducted
under this Agreement, whether or not patented or patentable, but excluding any
Mice Materials, Mice-Related Technology or Production Process Technology-, and
(b) Patents and other intellectual property rights with respect thereto
(collectively, "COLLABORATION PATENTS").

        "COMMERCIALLY REASONABLE EFFORTS" shall mean, with respect to the
research, development, manufacture or commercialization of a Collaboration
Target or a resulting Collaboration Product, efforts and resources commonly used
in the biotechnology industry for an antibody of similar commercial potential at
a similar stage in its lifecycle, taking into consideration its safety and
efficacy, its cost to develop, the competitiveness of alternative products, its
proprietary position, the likelihood of regulatory approval, its profitability,
and all other relevant factors. Commercially Reasonable Efforts shall be
determined on a market-by-market basis for each Collaboration Target and
Collaboration Product, as applicable

        "CONTROL" shall mean, with respect to any Information and Invention,
Patent or other intellectual property right, possession of the right, whether
directly or indirectly, and whether by ownership, license or otherwise, to
assign, or grant a license, sublicense or other right to or under, such
Information and Invention, Patent or fight as provided for herein without
violating the terms of any agreement or other arrangement with any Third Party.

        "CROSS-LICENSE AGREEMENT" shall mean that certain Cross-License
Agreement entered into by and among Abgenix, Inc., Cell Genesys, Inc., Japan
Tobacco Inc., Xenotech L.P., and GenPharm International, Inc., effective as of
March 26, 1997, as amended from time to time.

                                       43
<PAGE>   44

        "EXPLOIT" or "EXPLOITATION" shall mean to make, have made, import, use,
sell, offer for sale, or otherwise dispose of, including all discovery,
research, development, registration, modification, enhancement, improvement,
manufacture, storage, formulation, exportation, transportation, distribution,
promotion and marketing activities related thereto.

        "FDA" shall mean the United States Food and Drug Administration and any
successor agency thereto.

        "GAAP" shall mean United States generally accepted accounting principles
consistently applied.

        "HuMAb MICE" shall mean any * containing * into *, but * thereof, that
are Controlled by Medarex or its Affiliates as of the Effective Date or at any
time during the term of this Agreement, but excluding any * that are in-licensed
or otherwise acquired by Medarex or its Affiliates after the Effective Date.

        "IMPROVEMENT" shall mean any modification to an antibody, compound,
product or technology or any discovery, device, process or formulation related
to such antibody, compound, product or technology, whether or not patented or
patentable, including any enhancement in the efficiency, operation, manufacture,
ingredients, preparation, presentation, formulation. means of delivery,
packaging or dosage of an antibody, compound, product or technology, any
discovery or development of any new or expanded indications or applications for
an antibody, compound, product or technology, or any discovery or development
that improves the stability, safety or efficacy of an antibody, compound,
product or technology.

        "IND" shall mean an investigational new drug application filed with the
FDA for authorization to commence human clinical trials, and its equivalent in
other countries or regulatory jurisdictions.

        "INFORMATION AND INVENTIONS" shall mean all technical, scientific and
other know-how and information, trade secrets, knowledge, technology, means,
methods, processes, practices, formulas, instructions, skills, techniques,
procedures, experiences, ideas, technical assistance, designs, drawings,
assembly procedures, computer programs, apparatuses, specifications, data,
results and other material, including high-throughput screening, gene
expression, genomics, proteornics and other drug discovery and development
technology, pre-clinical and clinical trial results, manufacturing procedures,
test procedures and purification and isolation techniques, (whether or not
confidential, proprietary, patented or patentable) in written, electronic or any
other form now known or hereafter developed, and all Improvements, whether to
the foregoing or otherwise, and other discoveries, developments, inventions and
other intellectual property (whether or not confidential, proprietary, patented
or patentable)-

        "KIRIN AGREEMENT" shall mean that certain Agreement on Essential Terms
for Collaboration between Kirin Brewery Co, Ltd. ("KIRIN") and Medarex dated as
of December 27, 1999, and any further agreement between Kirin and Medarex
entered into pursuant thereto.

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       44
<PAGE>   45

        "KNOW-HOW" shall mean the Medarex Know-How (including the Mice-Related
Know-How), the Northwest Know-How and/or the Collaboration Know-How, as
applicable.

        "LEAD COLLABORATION ANTIBODY" shall have the meaning set forth in
Section 1.2.8. For the avoidance of doubt, a Collaboration Antibody that has
been designated a Lead Collaboration Antibody shall continue to be a
Collaboration Antibody for purposes of this Agreement.

        "MEDAREX KNOW-HOW" shall mean all Information and Inventions in the
Control of Medarex or its Affiliates as of the Effective Date or at any time
during the Term that are necessary or reasonably useful for the Exploitation of
the Collaboration Products or for the exercise of the Medarex Patents, in each
case that are not generally known, but excluding (w) any Third Party Know-How,
(x) any Information and Inventions included. in the Collaboration Technology,
(y) any Production Process Know-How, and (z) any Information and Inventions to
the extent covered or claimed by the Medarex Patents. Medarex Know-How shall
include all: (a) biological, chemical, pharmacological, toxicological,
pharmaceutical, physical and analytical, clinical and safety data and
information related to the Collaboration Targets and the Collaboration Products,
and (b) data and information with respect to, and resulting from, assays and
biological methodologies necessary or reasonably useful for the Exploitation of
the Collaboration Targets and the Collaboration Products. By way of
clarification, Northwest shall not have any rights with respect to Third-Party
Know-How under this Agreement unless the Parties enter into a separate written
agreement with respect thereto-

        "MEDAREX PATENTS" shall mean all of the Patents that Medarex or its
Affiliates Control as of the Effective Date and at any time during the Term,
that cover or claim any invention necessary or reasonably useful for the
Exploitation of the Collaboration Products, but excluding any Third Party
Patents, any Collaboration Patents, and any Production Process Patents. By way
of clarification, Northwest shall not have any rights with respect to any
Third-Party Patents under this Agreement unless the Parties enter into a
separate written agreement with respect thereto.

        "MEDAREX TECHNOLOGY" shall mean the Medarex Know-How and Medarex
Patents, including all Mice-Related Technology.

        "MICE MATERIALS" shall mean the HuMAb Mice, any parts or derivatives of
the HuMAb Mice, including * with respect to the * of an Antibody or * thereof,
and any * thereof or * thereto (e.g., * therein)) or other * derived directly or
indirectly from the HuMAb Mice, but excluding any Collaboration Products.

        "MICE-RELATED KNOW-HOW" shall mean (a) any Information and Inventions
with respect to any Mice Materials or other biological materials derived
directly or indirectly from the HuMAb Mice, but excluding any Collaboration
Products and any Information and Inventions with respect to Exploitation of
Collaboration Products, and (b) any Information and Inventions with respect to
the HuMAb Mice and the Exploitation thereof, but in each case excluding any
Information and Inventions to the extent covered or claimed by the Mice-Related
Patents.

        "MICE-RELATED PATENTS" shall mean any Patents that claim or cover (a)
Mice Materials or other biological materials derived directly or indirectly from
the HuMAb Mice, and any Information

    As Filed with the Securities and Exchange Commission on August 10, 2001.
 *INFORMATION HAS BEEN OMITTED PURSUANT TO A REQUEST FOR CONFIDENTIAL TREATMENT
   AND HAS BEEN FILED SEPARATELY WITH THE SECURITIES AND EXCHANGE COMMISSION.

                                       45
<PAGE>   46

and Inventions with respect to the foregoing, but excluding any claims with
respect to Collaboration Products or any Information and Inventions with respect
to the Exploitation of the Collaboration Products, and (b) the HuMAb Mice and
the Exploitation thereof

        "MICE-RELATED TECHNOLOGY" shall mean the Mice-Related Know-How and the
Mice-Related Patents.

        "MRC AGREEMENT" shall mean that certain License Agreement entered into
by the Medical Research Council Institute of Animal Physiology and Genetics
Research of Babraham Hall and Marianne Bruggdmann and GenPharm International,
Inc., effective October 1, 1993, as amended on August 12, 1994.

        "NORTHWEST KNOW-HOW" shall mean all Information and Inventions in the
Control of Northwest or its Affiliates as of the Effective Date or at any time
during the Term that are necessary or reasonably useful for the Exploitation of
the Collaboration Products, including the discovery, identification or
characterization of Collaboration Targets, or for the exercise of the Northwest
Patents, in each case that are not generally known, but excluding (x) any
Information and Inventions included in the Collaboration Technology, and (y) any
Information and Inventions to the extent covered or claimed by the Northwest
Patents. Northwest Know-How shall include all: (a) biological, chemical,
pharmacological, toxicological, pharmaceutical, physical and analytical,
clinical and safety data and information related to the Collaboration Targets
and the Collaboration Products, and (b) data and information with respect to,
and resulting from, assays and biological methodologies necessary or reasonably
useful for the Exploitation of the Collaboration Targets and the Collaboration
Products.

        "NORTHWEST PATENTS" shall mean all of the Patents that Northwest and its
Affiliates Control as of the Effective Date and at any time during the Term,
that claim or cover any invention necessary or reasonably useful for the
Exploitation of the Collaboration Products, including any Patents that claim or
cover any Collaboration Target or any method for the discovery, identification
or characterization of Collaboration Targets, but excluding any Collaboration
Patents.

        "NORTHWEST TECHNOLOGY" shall mean the Northwest Know-How and Northwest
Patents.

        "PATENTS" shall mean (x) all patents and patent applications, (y) any
substitutions, divisions, continuations, continuations-in-part, reissues,
renewals, registrations, confirmations, re-examinations, extensions,
supplementary protection certificates and the like, and any provisional
applications, of any such patents or patent applications, and (z) any foreign or
international equivalent of any of the foregoing.

        "PRE-EXISTING AGREEMENT" shall mean, with respect to an Antigen, any
agreement with a Third Party that would preclude such Antigen from becoming a
Collaboration Target hereunder that was entered into by Northwest or any of its
Affiliates, as applicable, prior to the Effective Date.

        "PRODUCT TRADEMARKS" shall mean the trademarks developed for the
Collaboration Products by the Steering Committee, all packaging designs and
other trade dress used in connection with the Collaboration Products and such
other Trademarks relating thereto and any registrations thereof or any pending
applications relating thereto.

                                       46
<PAGE>   47

        "PRODUCTION PROCESS DEVELOPMENT" shall mean the development of processes
and technology to facilitate production, purification, evaluation,
characterization, stability assessment, vialing and distribution, and release of
a Collaboration Antibody.

        "PRODUCTION PROCESS KNOW-HOW" shall mean any Information and Inventions
with respect to the Production Process Development or the manufacture of
Antibody Products, but excluding any Information and Inventions to the extent
covered or claimed by the Production Process Patents.

        "PRODUCTION PROCESS PATENTS" shall mean any Patents of Medarex that
claim or cover the Production Process Development or the manufacture of Antibody
Products.

        "PRODUCTION PROCESS TECHNOLOGY" shall mean any Production Process
Know-How and Production Process Patents.

        "REGULATORY APPROVAL" shall mean any and all approvals (including
pricing and reimbursement approvals), licenses, registrations or authorizations
of any Regulatory Authority, necessary for the Exploitation of a Collaboration
Product in a country, including any (a) approval for a Collaboration Product
(including any INDs, BLAs and supplements and amendments thereto); (b) pre- and
post-approval marketing authorizations (including any prerequisite manufacturing
approval or authorization related thereto); (c) labeling approval; and (d)
technical, medical and scientific licenses.

        "REGULATORY AUTHORITY" shall mean any applicable government entities
regulating or otherwise exercising authority with respect to the Exploitation of
the Collaboration Targets or the Collaboration Products in the Territory.

        "REGULATORY DOCUMENTATION" shall mean all applications, registrations,
licenses, authorizations and approvals (including all Regulatory Approvals), all
correspondence submitted to or received from Regulatory Authorities (including
minutes and official contact reports relating to any communications with any
Regulatory Authority), all supporting documents and all clinical studies and
tests, relating to any Collaboration Antibody, Collaboration Target or any
Collaboration Products, and all data contained in any of the foregoing,
including all regulatory drug lists, advertising and promotion documents,
adverse event files and complaint files.

        "TARGET ENTRY PERIOD" shall mean a four (4) year period starting on the
Effective Date (1) earlier terminated by (A) the unanimous agreement of the
Parties, or (B) either Party pursuant to Article 8; or (ii) extended by
unanimous agreement of the Parties. The termination or expiration of the Target
Entry Period shall not constitute a termination of this Agreement.

        "TECHNOLOGY" shall mean Medarex Technology, the Northwest Technology
and/or the Collaboration Technology, as applicable.

        "TERRITORY" shall mean the entire world.

        "THIRD PARTY" shall mean any party other than Medarex, Northwest or
their respective Affiliates,

                                       47
<PAGE>   48

        "THIRD-PARTY KNOW-HOW" shall mean any and all Information and Inventions
that Medarex or any of its Affiliates Control pursuant to the Biosite Agreement,
the Kirin Agreement or any other agreement with a Third Party that is entered
into after the Effective Date, but excluding any Information and Inventions that
are claimed or covered by the Third-Party Patents.

        "THIRD-PARTY PATENT" shall mean any Patents that Medarex or any of its
Affiliates Control pursuant to the Biosite Agreement, the Kirin Agreement or any
other agreement with a Third Party that is entered into after the Effective
Date.

        "TRADEMARK" shall include any word, name, symbol, color, designation or
device or any combination thereof, including any trademark, trade dress, service
mark, service name, brand mark, trade name, brand name, logo or business symbol.

        TERMS DEFINED ELSEWHERE IN THIS AGREEMENT. The following terms are
defined in the applicable Sections of this Agreement:

<TABLE>
<CAPTION>
DEFINED TERM                                    SECTION
<S>                                             <C>
Northwest Research Activities                   Section 1.2.4
Antigen Evaluation Material                     Section 1.2.2(a)
Assay                                           Section 1-2.3(c)
Assay Candidate                                 Section 1.2.6(a)
Assay Success Criteria                          Section 1.2.3(e)
Authorized Commercialization Expenses           Section 4. 1.1
Authorized R&D Expenses                         Section 4.1.2
Biological Materials                            Section 7.5.3
Collaboration                                   Section 1.1
Collaboration Antibody                          Section 1.2.6(a)
Collaboration Expenses                          Section 4.5.1
Collective Opinion of Counsel                   Section 7.4.1
Commercialization Expenses                      Appendix B
Confidential Information                        Section 6.1
Dormant Product                                 Section 5.3
Effective Date                                  Preamble
Election Notice                                 Section 5.1.2
Expert                                          Section 2.3. 1 (a)
Fully-Burdened Production Process Development   Appendix B
Cost
Immunogen                                       Section 1.2-3(a)
Indemnification Claim Notice                    Section 9.3.1
Indemnified Party                               Section 9.3.1
Indemnitee                                      Section 9.3.1
Infringement Suit                               Section 7.4.2
</TABLE>

                                       48
<PAGE>   49

<TABLE>
<CAPTION>
DEFINED TERM                                    SECTION
<S>                                             <C>
Initial Antigen                                 Section 1.2.2
Losses                                          Section 9.1
Medarex Research Activities                     Section 1.2.4
Net Profits, Net Losses                         Appendix B
Net Sales                                       Appendix B
Opt-Out                                         Section 5. 1. 1
Opt-Out Notice                                  Section 5. 1.1
Opting-Out Party                                Section 5. 1.1
Other Operating (Income)/Expense                Appendix B
Party                                           Preamble
Project Budget                                  Section 1.3
Project Plan                                    Section 1.3
Replacement Period                              Section 1.2.2(d)
Research and Commercialization Agreement        Section 3.3.2
Reserved Antibody                               Section 1.2.6(b)
Reversion Target                                Section 1.7
Steering Committee                              Section 2. 1.1
Subsequent Antigen                              Section 1.2.2
Term                                            Section 8.1
Third Party Claim                               Section 9.3.2
Third Party Payments                            Appendix B
Unilateral Development and Commercialization    Section 5.1.2
Agreement
Unilateral Product                              Section 5.1.2
Withholding Taxes                               Section 4.4
</TABLE>

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