Document:

EXHIBIT 4.11
                                                                    ------------

            CONSULTING AGREEMENT, dated the 10th day of September, 2001, by and
between CDKnet.com, Inc., a Delaware corporation having executive offices at 250
West 57th Street, Suite 1101, New York, New York (the "Company"), and Steven E.
Wildstein, an individual, (the "Consultant").

                              W I T N E S S E T H :

            WHEREAS, the Consultant has considerable knowledge of and experience
providing consulting services regarding the identification, evaluation,
structuring, negotiating and closing of joint ventures, strategic alliances and
business acquisitions as well as product development (the "Business"); and

            WHEREAS, the Company desires to obtain the benefit of Consultant's
special knowledge and experience regarding the identification, evaluation,
structuring, negotiating and closing of joint ventures, strategic alliances and
business acquisitions as well as product development; and

            WHEREAS, the Company's management has determined that it would be in
the best interest of the Company to make use of the Consultant's knowledge and
experience; and

            WHEREAS, Consultant desires to serve as consultant to the Company;

            NOW, THEREFORE, in consideration of the premises and the mutual
covenants and agreements herein contained the Company and the Consultant hereby
agree as follows:

            1. Term. The Company hereby engages Consultant to render the
consulting services as hereinafter set forth, and Consultant hereby agrees to
render such services for a period commencing the date hereof and terminating on
September 9, 2002 (the "Term").

            2. Consulting Services. The Company hereby retains the Consultant,
and the Consultant agrees, to render consulting and advisory services to the
Company during the Term hereof in connection with the Business, from time to
time, and as the Chief Executive Officer of the Company may reasonably request.
Consultant shall not be required to expend any minimum number of hours hereunder
and the rendering of all consulting services shall be subject in priority to
Consultant's own business interests.

            3. Consulting Fees. In consideration for (i) the availability of
Consultant to render the services, (ii) the services to be rendered by
Consultant during the Term, and (iii) the other provisions of this Agreement,
the Company shall promptly issue to the Consultant 500,000 shares fo the
Company's common stock, which shares shall be subject to S-8 Registration.

            4. Expenses. Upon submission of proper vouchers or other similar
evidence of expenditures, the Company shall, upon request by Consultant,
reimburse Consultant for all reasonable travel and out-of-pocket expenses
incurred by Consultant in connection with services requested and rendered
hereunder. All expense items require the prior approval of the Company.
<PAGE>

            5. Notices. All notices, requests, demands and other communications
hereunder shall be in writing and shall be deemed to have been duly given when
either served personally or two (2) business days after being sent priority next
day delivery by a nationally recognized courier or three (3) business days after
being mailed by certified or registered mail, return receipt requested; if to
the Company or to Consultant, then at the respective address first above
written, and in each case with a copy to: Moritt, Hock, Hamroff & Horowitz, LLP,
400 Garden City Plaza, Suite 202, Garden City, New York 11530 or to such address
or to such persons as either party shall have last designated by written notice
to the other.

            6. Assignability. This Agreement shall inure to the benefit of and
be binding upon the parties, their successors and permitted assigns. Neither
party may assign this Agreement or its rights or obligations hereunder without
the prior written consent of the other party.

            7. Entire Agreement. This instrument constitutes the entire
agreement of the parties hereto with respect to the subject matter hereof and
supercedes all prior agreements and understandings, written or oral, among them
with respect to the subject matter hereof. This Agreement may be modified only
by a written instrument signed by the parties.

            8. Governing Law. This Agreement shall be governed by and construed
(both as to validity and performance) and enforced in accordance with the laws
of the State of New York without giving effect to the conflicts or choice of law
provisions thereof.

            9. Counterparts. This Agreement may be executed in counterparts each
of which shall be deemed an original and all of which taken together shall
constitute one and the same agreement.

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

                                            CDKnet.com, Inc.

                                            By: /s/ Steven A. Horowitz
                                                ---------------------------
                                                Steven A. Horowitz, C.E.O.

                                            Consultant:

                                                /s/ Steven E. Wildstein
                                                ---------------------------
                                                Steven E. Wildstein<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.

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                                (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.

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<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.

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                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.

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<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.

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<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

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<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

                                       28
<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

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<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

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<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

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<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>

                                       49
<PAGE>   50

                                                                    CONFIDENTIAL

                                   APPENDIX B
                              FINANCIAL 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
of financial terms 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 B are hereby incorporated into the
Agreement and are governed by the terms and conditions of the Agreement,
including the confidentiality provisions set forth therein.

            It is the intention of the Parties that the interpretation of these
definitions will be in accordance with GAAP.

        1. "NET SALES" shall mean, for any period, the gross amount invoiced by
the Parties and their Affiliates and sublicensees for the sale of Collaboration
Product(s) to Third Parties, less deductions for: (a) normal and customary
trade, quantity and cash discounts and sales returns and allowances (other than
allowances for doubtful accounts), including (i) those granted on account of
price adjustments, billing errors, rejected goods, damaged goods, returns and
rebates, (ii) administrative and other fees and reimbursements and similar
payments directly related to the sale or delivery of Collaboration Product(s)
paid to wholesalers and other distributors, buying groups, pharmacy benefit
management organizations, health care insurance carriers and other institutions,
(iii) allowances, rebates and fees directly related to the sale or delivery of
Collaboration Product(s) paid to distributors and (iv) chargebacks; (b) freight,
postage, shipping and insurance costs to the extent that such items are included
in the gross amount invoiced; (c) customs and excise duties and other duties
related to the sales to the extent that such items are included in the gross
amount invoiced; (d) rebates and similar payments made with respect to sales
paid for or reimbursed by any governmental or regulatory authority such as, by
way of illustration and not in limitation of the Parties' rights hereunder,
Federal or state Medicaid, Medicare or similar state program or equivalent
foreign governmental program; (e) sales and other taxes and duties directly
related to the sale or delivery of Collaboration Product(s) (but not including
taxes assessed against the income derived from such sale); (f) distribution
costs and expenses to the extent that such items are included in the gross
amount invoiced; and (g) any such invoiced amounts that are not collected by the
Parties or their Affiliates or sublicensees; provided, however, that an amount
shall be deducted only once regardless of how many categories may apply to it.
Any of the deductions listed above that involves a payment by a Party or its
Affiliates or sublicensees shall be taken as a deduction in the calendar quarter
in which the payment is accrued by such entity. Deductions pursuant to
subsection (g) above shall be taken in the calendar quarter in which such sales
are no longer recorded as a receivable. For purposes of determining Net Sales,
the

<PAGE>   51

Collaboration Product(s) shall be deemed to be sold when invoiced and a "sale"
shall not include transfers or dispositions for charitable, promotional,
pre-clinical, clinical, regulatory or governmental purposes.

        For purposes of calculating Net Sales of Collaboration Products, sales
between or among the Parties or their Affiliates shall be excluded from the
computation of Net Sales, but sales by a Party or its Affiliates to sublicensees
or Third Parties shall be included in the computation of Net Sales.

        2. "NET PROFITS" and, with correlative meaning, "NET LOSSES", shall
mean, with respect to a Collaboration Product, Net Sales of such Collaboration
Product less Authorized Commercialization Expenses (to the extent not already
deducted from Net Sales) and Other Operating (Income)/Expense with respect to
such Collaboration Product, all for a given period.

        3. "COMMERCIALIZATION EXPENSES" shall mean all Cost of Sales,
Distribution Costs, Marketing Costs, Sales Costs, General and Administrative
Costs (in each case, to the extent not deducted from Net Sales under Section 1
hereof) of the Parties and their Affiliates with respect to the Collaboration
Products.

            3.1 "COST OF SALES" shall mean (a) the supply price, and any other
        direct costs and expense of acquiring, including costs of transport,
        customs, clearance and storage of product (if necessary), freight,
        customs, duty, and insurance borne by the Parties (to the extent not
        included in such supply price), with respect to Net Sales of a
        Collaboration Product, and (b) any Third Party Payments with respect to
        such Net Sales, to the extent not included in such supply price or
        reimbursed by a Third Party.

                3.1.1 "THIRD PARTY PAYMENTS" shall mean intellectual property
            and technology acquisition and license costs and expenses (including
            royalties, license fees, milestone payments and other payment
            obligations) paid to Third Parties with respect to a Collaboration
            Product, including any payments made pursuant to the MRC Agreement.

            3.2 "DISTRIBUTION COSTS" shall mean the costs and expenses
        specifically identifiable to the distribution of a Collaboration Product
        by a Party including customer services, collection of data about sales
        to hospitals and other end users, order entry, billing, shipping, credit
        and collection and other such activities, but in any case, not including
        any costs or expenses which are reimbursed by any Third Party.

            3.3 "MARKETING COSTS" shall mean, with respect to a Collaboration
        Product, the direct costs and expenses of marketing, promotion,
        advertising, promotional materials, professional education,
        product-related public relations, relationships with opinion leaders and
        professional societies, market research (before and after Regulatory
        Approval of a Collaboration Product), healthcare economics studies,
        post-marketing studies required to maintain or expand

                                      B-2
<PAGE>   52

        Regulatory Approvals of such Collaboration Product (to the extent not
        included in Authorized R&D Expenses) and other similar activities
        related to such Collaboration Product and approved by the Steering
        Committee. Such costs and expenses will include both internal costs
        (e.g., salaries, benefits, supplies and materials, etc.) and costs of
        outside services and expenses (e.g., consultants, agency fees, meeting
        costs, etc.). Marketing Costs shall also include costs and expenses
        directly related to obtaining reimbursement from payers and the cost of
        obtaining sales and marketing data (to the extent not included in the
        Distribution Costs). Notwithstanding anything to the contrary in the
        foregoing, Marketing Costs shall specifically exclude the cost and
        expense of activities that promote a Party's business as a whole without
        being specific to a Collaboration Product (e.g., corporate image
        advertising).

            3.4 "SALES COSTS" shall mean, with respect to a Collaboration
        Product, costs and expenses approved by the Steering Committee in the
        annual budget for the commercialization of such Collaboration Product,
        incurred by either Party or for its account and specifically
        identifiable to the sales efforts for such Collaboration Product in all
        markets in the Territory including the managed care market. Sales Costs
        shall include costs and expenses associated with sales representatives
        for a Collaboration Product, including the cost of compensation,
        benefits, travel, supervision, training, sales meetings, and other sales
        expenses for such sales representatives. Notwithstanding anything to the
        contrary in the foregoing, Sales Costs shall exclude costs and expenses
        associated with the start-up of a Party's sales force, including
        recruiting, relocation and other similar costs and expenses.

            3.5 "GENERAL AND ADMINISTRATIVE COSTS" shall mean, with respect to a
        Collaboration Product, costs equal to ten percent (10%) of the sum of
        the Distribution Costs, Marketing Costs and Sales Costs related to such
        Collaboration Product in any country, of the Parties, in the aggregate,
        but only to the extent these costs are chargeable under the Agreement.
        Each Party shall have the right to charge General and Administrative
        Costs with respect to its Distribution Costs, Marketing Costs and Sales
        Costs chargeable under the Agreement.

        4. "OTHER OPERATING (INCOME)/EXPENSE" shall mean (a) payments and other
consideration received from Third Parties with respect to the commercialization
of a Collaboration Product, including any license fees, milestone payments,
royalties or other payments (including the fair market value of any
consideration received) in connection with the license, sublicense, assignment
or transfer of rights with respect to such Collaboration Product (to the extent
not included in Net Sales), and (b) any other operating income received from or
expense owed to Third Parties in connection with an activity that is not part of
the primary business activity of a Party under the Agreement but is considered
and approved by the Parties as income or expense for purposes of the Agreement,
which may include: (i) actual inventory write-offs of any Collaboration Product;
(ii) the cost and expense of prosecuting, maintaining and enforcing patent,
trademark and other intellectual property rights and defending against claims of

                                      B-3
<PAGE>   53

infringement; and (iii) product liability insurance to the extent the Parties
obtain a joint policy.

        5. "FULLY-BURDENED PRODUCTION PROCESS DEVELOPMENT COSTS" shall mean,
with respect to each Collaboration Antibody, One Hundred Percent (100%) of the
consolidated fully burdened cost of Production Process Development of such
Collaboration Antibody, which shall include (a) direct labor and material costs,
(b) substrate and product quality assurance/control costs, (c) costs of any
stability studies, (d) costs of losses or wastage in process development, to the
extent not the result of negligence or the use of non-standard operating
procedures, (e) facility and equipment depreciation costs, (f) facility and
equipment validation and control costs, (g) costs associated with evaluation of
safety profile, activity and quality of material in in vitro and in vivo uses,
(h) costs required for manufacturing material for in vitro and in vivo uses, (i)
costs associated with submission and maintenance of regulatory documentation,
(j) shipping costs, (k) costs related to subcontracted work, (l) expenses with
respect to each of the foregoing (a) through (k), (m) applicable allocable
overhead, as determined in accordance with GAAP as applied by Medarex, (n)
twenty-five percent (25%) of the sum of the components (a) through (m), and (o)
all of the manufacturer's allocable intellectual property and technology
acquisition and license costs and expenses (including royalties, license fees,
milestone payments and other payment obligations) paid to Third Parties with
respect to Production Process Development of a Collaboration Antibody.

                                      B-4
<PAGE>   54

                                  APPENDIX C-1
                                INITIAL ANTIGENS

        This Appendix to the COLLABORATION AGREEMENT ("AGREEMENT") effective as
of April 24, 2001, by and between NORTHWEST BIOTHERAPEUTICS, INC. ("NORTHWEST")
and MEDAREX, INC., on behalf of itself and its wholly owned subsidiary, GENPHARM
INTERNATIONAL, INC., (collectively, "MEDAREX") sets forth the Initial Antigens.

        The contents of this Appendix C-1 are hereby incorporated into the
Agreement and are governed by the terms and conditions of the Agreement,
including the confidentiality provisions set forth therein.

    INITIAL ANTIGENS          DESCRIPTION
    ----------------          -----------
           #1                 PSMA
           #2                 CXCR4
           #3                 Fucosyl-GM1
           #4                 FLT4

<PAGE>   55

                                  APPENDIX C-2
                              COLLABORATION TARGETS

        This Appendix to the COLLABORATION AGREEMENT ("AGREEMENT") effective as
of April 24, 2001, by and between NORTHWEST BIOTHERAPEUTICS, INC. ("NORTHWEST")
and MEDAREX, INC., on behalf of itself and its wholly owned subsidiary, GENPHARM
INTERNATIONAL, INC., (collectively, "MEDAREX") sets forth the Collaboration
Targets.

        The contents of this Appendix C-2 are hereby incorporated into the
Agreement and are governed by the terms and conditions of the Agreement,
including the confidentiality provisions set forth therein.

     COLLABORATION              DESCRIPTION
        TARGETS

<PAGE>   56

                                  APPENDIX D-1
             UNILATERAL DEVELOPMENT AND COMMERCIALIZATION AGREEMENT

        This Appendix to the COLLABORATION AGREEMENT ("AGREEMENT") effective as
of April 24, 2001, by and between NORTHWEST BIOTHERAPEUTICS, INC. ("NORTHWEST")
and MEDAREX, INC., on behalf of itself and its wholly owned subsidiary, GENPHARM
INTERNATIONAL, INC., (collectively, "MEDAREX") sets forth the Unilateral
Development and Commercialization Agreement between the Parties. 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 D-1 are hereby incorporated into the
Agreement and are governed by the terms and conditions of the Agreement,
including the confidentiality provisions set forth therein.

<PAGE>   57

                                  APPENDIX D-1
                             UNILATERAL DEVELOPMENT
                         AND COMMERCIALIZATION AGREEMENT

        THIS UNILATERAL DEVELOPMENT AND COMMERCIALIZATION 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 have entered into that certain
Collaboration Agreement, dated as of the date hereof (the "COLLABORATION
AGREEMENT");

        WHEREAS, the Parties have agreed that in the event Medarex elects not to
proceed with the development and commercialization of certain Collaboration
Targets and Northwest notifies Medarex of its election to proceed unilaterally
with such development and commercialization in accordance with Section 5.1.2 of
the Collaboration Agreement, that Northwest shall have the right to do so in
accordance with the terms set forth below; and

        WHEREAS, the Parties have agreed that in the event Medarex fails to
comply with any of its material obligations contained to the Collaboration
Agreement with respect to a Collaboration Product, Northwest shall have the
right to convert such Collaboration Product into a Unilateral Product in
accordance with Section 8.2 of the Collaboration Agreement and proceed
unilaterally with the development and commercialization of such Unilateral
Product in accordance with 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 -
                  UNILATERAL DEVELOPMENT AND COMMERCIALIZATION

        SECTION 1.1 DEFINITIONS. Any capitalized term used in this Agreement not
otherwise defined herein shall have the meaning set forth in the Collaboration
Agreement.

                                       1
<PAGE>   58

        SECTION 1.2 UNILATERAL TARGETS, ANTIBODIES AND PRODUCTS. In the event
that Northwest provides Medarex with (a) an Election Notice with respect to a
Collaboration Target pursuant to Section 5.1.2 of the Collaboration Agreement,
or (b) written notice of Medarex's failure to cure a default in any of its
material obligations with respect to a Collaboration Product with respect to a
Collaboration Target pursuant to Section 8.2 of the Collaboration Agreement,
Appendix A hereto shall be amended to include such Collaboration Target and any
Collaboration Antibodies with respect thereto, which Collaboration Targets and
Collaboration Antibodies shall be referred to herein as "Unilateral Targets" and
"Unilateral Antibodies," respectively. Northwest shall have the exclusive right
to Exploit any and all Antibody Products with respect to the Unilateral Targets
(each such Antibody Product, a "UNILATERAL PRODUCT"), including any
Collaboration Products with respect to such Unilateral Targets developed or
commercialized pursuant to the Collaboration Agreement or any other Antibody
Products containing or comprising Unilateral Antibodies.

        SECTION 1.3 RIGHTS AND OBLIGATIONS OF THE PARTIES WITH RESPECT TO
UNILATERAL PRODUCTS. Except as otherwise expressly provided herein, Northwest
shall be solely responsible for all costs and expenses in connection with the
development and commercialization of the Unilateral Products; provided, however,
that Medarex shall be responsible for all budgeted costs and expenses associated
with the research and development activities with respect to the Unilateral
Products that Medarex has committed to in the applicable Project Budget as
necessary to complete that phase (e.g., toxicology studies in support of an IND
or Phase 1, Phase II or Phase III) of research and development that was under
way when Medarex Opted-Out of such Unilateral Products. By way of clarification,
Northwest shall be responsible, at its sole cost, for all milestone and royalty
payments, license fees and other payments owed to Third Parties, whether by
Northwest, Medarex or their respective Affiliates, in connection with the
development and commercialization of Unilateral Products, including any payments
owed by Medarex and its Affiliates under the Biosite Agreement or the MRC
Agreement. The Parties shall work together to ensure a smooth and orderly
transition of the Unilateral Products to Northwest, including the assignment of
any contracts with respect to the Exploitation of such Unilateral Products to
Northwest, and the assumption by Northwest of any obligations thereunder. Except
for the obligations provided for in this Section 1.3, Medarex shall have (a) no
further financial obligation to support or otherwise fund any additional efforts
in respect of such Unilateral Products, and (b) no obligation, responsibility,
or authority regarding such additional efforts in respect of such Unilateral
Products.

        SECTION 1.4 PERFORMANCE OF NORTHWEST. Northwest shall use Commercially
Reasonable Efforts to develop and commercialize one or more Unilateral Products
with respect to each Unilateral Target. Such activities shall be performed in
good scientific manner, and in compliance in all material respects with all
Applicable Law, including current good laboratory practices and good clinical
practices (including compliance with such practices and guidelines necessary to
allow the results of such activities to support INDs, BLAB and other Regulatory
Approvals), as applicable Northwest shall have the right, subject to the
obligations set forth in this Section 1.4, to license to Third Parties rights
with respect to the development or commercialization of a Unilateral Product in
its

                                       2
<PAGE>   59

sole discretion; provided that any such Third Party enters into a written
agreement with Northwest to indemnify Medarex and its Affiliates to the extent
provided in Article 7, and to be bound by the provisions of Articles 4 and 5 and
Section 1.3; provided, however, that any sublicense with respect to the Medarex
Technology shall be governed by the procedures set forth in Sections 2.2.5 and
2.3.

        SECTION 1.5 NORTHWEST REPORTS. Northwest shall provide an annual written
progress report to Medarex describing the development and commercialization
activities with respect to each of its Unilateral Products in sufficient detail
to enable Medarex to determine whether Northwest is using Commercially
Reasonable Efforts with respect thereto.

        SECTION 1.6 COMMUNICATIONS AND FILINGS WITH REGULATORY AUTHORITIES.
Northwest shall be responsible for all communications and filings with the
Regulatory Authorities with respect to each of its Unilateral Products.

        SECTION 1.7 OPT-OUT BY NORTHWEST. If, at any time, Northwest decides to
cease development or commercialization of all Unilateral Products with respect
to a Unilateral Target, either alone or in collaboration with or through a Third
Party, it shall give prompt written notice thereof to Medarex, which notice
shall describe in reasonable detail the reasons for such decision. Northwest
shall, for a period of thirty (30) days after notice to Medarex with respect
thereto, furnish Medarex with such information and materials as Medarex may
reasonably request so as to determine whether it wishes to proceed with the
unilateral development and commercialization of such Unilateral Products. Upon
its receipt of all of such information and materials, Medarex shall, for a
period of thirty (30) days, have the right to elect to proceed unilaterally with
the development and commercialization of such Unilateral Products. Upon such
election, Appendix A shall be amended to delete such Unilateral Target and any
Unilateral Antibodies with respect thereto, and the Unilateral Development and
Commercialization Agreement set forth in Appendix D-2 to the Collaboration
Agreement shall be automatically amended to include such Unilateral Target and
such Unilateral Antibodies, provided that the royalty rate with respect to such
Unilateral Products shall be the rate that Northwest would have owed to Medarex
had it not elected to cease development or commercialization of such Unilateral
Products. By way of clarification, Northwest shall have the right to pursue one
or more Unilateral Products with respect to a Unilateral Target and any decision
to cease Exploiting one in favor of another shall not be subject to this Section
1.7 for so long as Northwest is using Commercially Reasonable Efforts to develop
and commercialize at least one Unilateral Product with respect to such
Unilateral Target.

                                   ARTICLE 2 -
                                 LICENSE GRANTS

        SECTION 2.1 MEDAREX GRANT. Subject to Section 2.2 and the other terms
and conditions of this Agreement, Medarex hereby grants to Northwest and its
Affiliates, with respect to each Unilateral Product, an exclusive (even as to
Medarex and its Affiliates), royalty-bearing license, with the right to
sublicense solely as provided in Section 2.3,

                                       3
<PAGE>   60

under the Medarex Technology, the Collaboration Technology and the Joint
Technology to Exploit such Unilateral Products in the Territory in accordance
with this Agreement.

        SECTION 2.2 EXCLUSIVITY, RESERVED RIGHTS AND PRE-EXISTING GRANTS.

            2.2.1 ANTIGEN EXCLUSIVITY. Subject to Sections 2.2.2 and 2.2.4, the
Parties acknowledge and agree 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 Unilateral Target listed on Appendix A other than the
Unilateral Products as provided in this Agreement.

            2.2.2 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
Antibody Products containing or comprising Unilateral Antibodies) with respect
to Antigens, including Unilateral 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").

            2.2.3 RETAINED RIGHTS.

                (a) OTHER ANTIGENS. Notwithstanding anything in this Agreement
to the contrary, Medarex shall have and retain the right to (i) enter into
collaborations with, and to grant licenses and other rights under the Medarex
Technology to, Third Parties to Exploit Antibody Products with respect to
Antigens other than Unilateral Targets, and/or (ii) independently Exploit
Antibody Products with respect to Antigens other than Unilateral Targets.

                (b) NON-ANTIBODY PRODUCTS. Notwithstanding anything in this
Agreement to the contrary, each Party shall have and retain the right to (i)
enter into collaborations with, and to grant licenses and other rights under its
respective Technology (other than Joint Technology and Collaboration Technology,
which shall be governed by Section 5.1.3 and the Collaboration Agreement,
respectively) to, Third Parties to Exploit products other than antibody-based
products with respect to Unilateral Targets, and/or (ii) independently Exploit
products other than antibody-based products with respect to Unilateral Targets.

            2.2.4 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
with respect to Antigens, including the Unilateral Targets, in the Territory.

                                       4
<PAGE>   61

            2.2.5 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. So long as the Cross-License Agreement is in effect,
if Northwest desires to grant a sublicense with respect to commercialization of
a Unilateral Product pursuant to Section 2.3, then Northwest 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
Unilateral 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.

                (a) 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 Northwest in writing and
Northwest thereafter shall have the right to grant such sublicense, subject to
Section 2.3.

                (b) 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 Northwest in writing. The
Parties shall then meet to discuss in good faith how to proceed in order to
optimize the commercialization of the applicable Unilateral Product hereunder
while complying with the requirements of the Cross-License Agreement.

        SECTION 2.3 SUBLICENSES. Subject to Section 2.2.5, Northwest shall have
the right to grant to Third Parties sublicenses under the license granted in
Section 2.1 only with the prior written consent of Medarex, not to be
unreasonably withheld or delayed, which approval shall be deemed to be granted
with respect to a sublicense if Medarex fails, within ten (10) days of its
receipt of a written notice from Northwest setting forth in reasonable detail
the nature of such sublicense and the identity of the sublicensee, to notify
Northwest in writing that it withholds its consent to such sublicense; provided,
however, that the grant of any such sublicense shall not relieve Northwest of
its obligations under this Agreement.

        SECTION 2.4 LICENSE LIMITATIONS. Northwest hereby covenants to Medarex
that neither Northwest nor any of its Affiliates, licensees or sublicensees
shall use or practice the Medarex Technology, directly or indirectly, on behalf
of itself or any other party, for any purpose other than as permitted under
Section 2.1 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
Unilateral Product as provided hereunder or a Collaboration Product as provided
in the Collaboration Agreement.

        SECTION 2.5 NO OTHER RIGHTS. For the avoidance of doubt, 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 2.1 of
this Agreement and Section 3.1 of the Collaboration Agreement.

                                       5
<PAGE>   62

                                   ARTICLE 3 -
                              FINANCIAL PROVISIONS

        Section 3. 1 MILESTONE PAYMENTS. Within thirty (30) days of the
achievement of the following milestones, on a Unilateral Target-by-Unilateral
Target basis, for Unilateral Products with respect to each Unilateral Target,
Northwest shall pay to Medarex the specified milestone payments, each of which
shall be nonrefundable

<TABLE>
<CAPTION>
                              1ST UNILATERAL              2ND UNILATERAL             EACH ADDITIONAL
                              PRODUCT WITH                PRODUCT WITH               UNILATERAL PRODUCT
                              RESPECT TO A                RESPECT TO A               WITH RESPECT TO A
MILESTONES                    UNILATERAL TARGET           UNILATERAL TARGET          UNILATERAL TARGET
----------                    -----------------           -----------------          -----------------
<S>                           <C>                         <C>                        <C>
IND Filing                      $    500,000               $    500,000               $    500,000
Commencement of
Phase II                        $  1,000,000               $  1,000,000               $  1,000,000

Commencement of
Phase III                       $  1,500,000               $  1,500,000               $  1,500,000

BLA Filing or
equivalent in a
Major Market                    $  2,000,000               $  2,000,000               $  2,000,000

Upon approval of
first BLA or
equivalent in a
Major Market                    $  2,000,000               $  1,500,000               $  1,000,000

Upon approval of
BLA or equivalent
in a second Major
Market                          $  1,500,000               $  1,000,000               $    500,000
</TABLE>

        SECTION 3.2 Royalties

            3.2.1 OBLIGATION. With respect to each Unilateral Product, Northwest
shall pay Medarex royalties based upon the annual worldwide Net Sales (on a
calendar year basis) for such Unilateral Product. The royalty rates shall be
determined on a Unilateral Target-by-Unilateral Target basis based on the
aggregate Net Sales of each Unilateral Product with respect to such Unilateral
Target and on the stage of development and commercialization that the first
Collaboration Product with respect to such Unilateral Target had achieved when
such Collaboration Target was designated as a Unilateral Target.

            3.2.2 RATES. The royalty rates for each Unilateral Product (a) for
which Medarex Opted-Out pursuant to Section 5.1.1 of the Collaboration
Agreement, or (b) which was converted from a Collaboration Product pursuant to
Section 8.2 of the Collaboration Agreement upon Medarex's default in any of its
material obligations shall be as follows:

                                       6
<PAGE>   63

<TABLE>
<CAPTION>
         OPT-OUT OR TERMINATION PHASE                  ROYALTY
        -----------------------------                  -------
<S>                                                    <C>
Prior to the first Phase I Completion in a Major
Market                                                    2%

Post-Phase I Completion to the first Phase II
Completion in a Major Market                              3%

Post-Phase II Completion in a Major Market                5%
</TABLE>

If an Opt-Out (as opposed to a termination event) occurs within thirty (30) days
after the end of a Phase, the royalty rate shall be calculated based on such
recently expired Phase.

        3.2.3 DEFINITIONS. For purposes of this Agreement, the following
definitions shall apply:

            (a) "MAJOR MARKET" shall mean each of Japan, the United States, the
United Kingdom, France, Germany and the European Union as a whole.

            (b) "PHASE I" shall mean a human clinical trial, the principal
purpose of which is a preliminary determination of safety in healthy individuals
or patients as required in 21 C.F.R. Section 312, or a similar clinical study
prescribed by the Regulatory Authorities in a Major Market other than the United
States.

            (c) "PHASE I COMPLETION" shall mean, with respect to a Unilateral
Target, the completion of a complete data package from (i) a Phase I study,
which data package is sufficient to support the commencement of Phase II studies
in support of the filing of an approvable BLA in a Major Market, or (ii) in the
event that Phase I and Phase II are combined, the first study in support of the
filing of an approvable BLA in a Major Market that enrolled at least twenty (20)
subjects, in either case for the first Collaboration Product with respect to
such Collaboration Target.

            (d) "PHASE II" shall mean a human clinical trial, for which a
primary endpoint is a preliminary determination of efficacy or dose ranges in
patients with the disease target being studied as required in 21 C F.R Section
312, or a similar clinical study prescribed by the Regulatory Authorities in a
Major Market other than the United States. Any well-controlled study intended to
provide the substantial evidence of efficacy necessary to support the filing of
an approvable BLA (such as a combined Phase II/Phase III study, or any Phase III
study in lieu of a Phase II study) (a "PIVOTAL STUDY") shall automatically be
deemed to have reached Phase II status. A Phase II study shall be deemed to have
commenced when the first subject in such study has been enrolled.

            (e) "PHASE II COMPLETION" shall mean, with respect to a Unilateral
Target, the completion of a complete data package from (a) Phase II studies,
which data package is sufficient to support the commencement of Phase III
studies in support of the filing of an approvable BLA in a Major Market, or (b)
in the event that Phase II and III studies are combined, the first such study in
support of the filing of an approvable BLA

                                       7
<PAGE>   64

in a Major Market that enrolled at least forty (40) patients with the disease
target being studied, in either case for the first Collaboration Product with
respect to such Collaboration Target.

            (f) "PHASE III" shall mean a human clinical trial, the principal
purpose of which is to establish safety and efficacy in patients with the
disease target being studied as required in 21 C.F.R. Section 312, or similar
clinical study prescribed by the Regulatory Authorities in a Major Market other
than the United States. A Phase III study shall also include any other human
clinical trial intended as a Pivotal Study, whether or not such study is a
traditional Phase III study. A Phase III study shall be deemed to have commenced
when the first patient has been enrolled in a Pivotal Study.

            (g) "PHASE III COMPLETION" shall mean, with respect to a Unilateral
Target, the completion of a data package for a Phase III study with respect to
the first Unilateral Product with respect to such Unilateral Target, which data
package is sufficient to support the filing of an approvable BLA for such
Unilateral Product in a Major Market.

        SECTION 3.3 ROYALTY TERM. Northwest's royalty obligations under Section
3.2.2 shall terminate, on a country-by-country basis, with respect to each
Unilateral Product with respect to a Unilateral Target, on the later to occur of
(a) the tenth (10th) anniversary of the first sale for use or consumption by the
general public of such Unilateral Product in a country after Regulatory Approval
has been obtained for such Unilateral Product in such country (the "FIRST
COMMERCIAL SALE"), and (b) the expiration date in such country of the last to
expire of any issued Joint Patent or Medarex Patent that includes at least one
Valid Claim covering the Exploitation of such Unilateral Product in such
country. Upon termination of the royalty obligations of Northwest under this
Section 3.3 in a country, the license grants to Northwest in Section 2.1 shall
become fully-paid with respect to such country.

        SECTION 3.4 ROYALTY PAYMENTS. Running royalties shall be payable on a
quarterly basis, within forty-five (45) days after the end of each calendar
quarter, based upon the Net Sales during such calendar quarter, commencing with
the calendar quarter in which the First Commercial Sale of a Unilateral Product
is made. Royalties shall be calculated in accordance with GAAP and with the
terms of this Article 3. Only one royalty payment will be due on Net Sales of a
given Unilateral Product even though the manufacture, sale or use of such
Unilateral Product may be covered by more than one intellectual property right
in a country.

        SECTION 3.5 ROYALTY STATEMENTS. Northwest shall deliver to Medarex
within forty-five (45) days after the end of each calendar quarter in which
Unilateral Products, for which Northwest owes a royalty hereunder, are sold, a
detailed statement showing (a) Net Sales of each such Unilateral Product, (b)
the number of units of each such Unilateral Product sold on a country-by-country
basis during the applicable calendar quarter, and (c) the amount and calculation
of royalties due on such Net Sales.

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<PAGE>   65

        SECTION 3.6 PAYMENT METHOD. All amounts due by Northwest hereunder shall
be paid in U.S. dollars by wire transfer in immediately available funds to an
account designated by Medarex. 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 (2) percentage points, or
the maximum rate permitted by law, calculated on the number of days such payment
is delinquent, compounded monthly.

        SECTION 3.7 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 royalty payments relate. If at any time
legal restrictions prevent the prompt remittance of any royalties with respect
to Net Sales in any jurisdiction, Northwest may notify Medarex 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 Medarex, and Northwest shall
have no further obligations under this Agreement with respect thereto.

        SECTION 3.8 TAXES. Northwest may deduct from any royalty amounts it is
required to pay pursuant to this Agreement any Withholding Taxes. At Medarex's
request, Northwest shall provide Medarex a certificate evidencing payment of any
Withholding Taxes hereunder and shall reasonably assist Medarex, at Medarex's
expense, to obtain the benefit of any applicable tax treaty.

        SECTION 3.9 RECORDS RETENTION; AUDIT.

            3.9.1 RECORD RETENTION. Northwest shall maintain (and shall ensure
that its Affiliates and sublicensees shall maintain) complete and accurate
books, records and accounts that fairly reflect their respective Net Sales of
Unilateral Products 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 Northwest until the later of (a) three (3) years
after the end of the period to which such books, records and accounts pertain,
and (b) 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.

            3.9.2 AUDIT. Medarex shall have the right to have an independent
certified public accounting firm of nationally recognized standing, reasonably
acceptable to Northwest, to have access during normal business hours, and upon
reasonable prior written notice, to such of the records of Northwest (and its
Affiliates and sublicensees) as may be reasonably necessary to verify the
accuracy of such Net Sales for any calendar quarter ending not more than
thirty-six (36) months prior to the date of such request, provided, however,
that Medarex shall not 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 Net Sales are correct or incorrect and the specific details
concerning any discrepancies. No other information shall be provided to Medarex
Medarex shall bear

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<PAGE>   66

the cost of such audit unless the audit reveals a variance of more than five
percent (5%) from the reported results, in which case Northwest shall bear the
cost of the audit. The results of such accounting firm shall be final, absent
manifest error.

            3.9.3 PAYMENT OF ADDITIONAL ROYALTIES. If, based on the results of
such audit, additional payments are owed by Northwest under this Agreement,
Northwest shall make such additional payments, with interest from the date
originally due as provided in Section 3.6, within forty-five (45) days after the
date on which such accounting firm's written report is delivered to Northwest.

        SECTION 3.10 CONFIDENTIALITY. Medarex shall treat all information
subject to review under Section 3.9 in accordance with the confidentiality
provisions of Article 4 and shall cause its accounting firm to enter into a
reasonably acceptable confidentiality agreement with Northwest obligating such
firm to maintain all such financial information in confidence pursuant to such
confidentiality agreement.

                                   ARTICLE 4 -
                                 CONFIDENTIALITY

        SECTION 4.1 CONFIDENTIAL INFORMATION. The confidentiality and use
restrictions set forth in Sections 6.1 through 6.4 of the Collaboration
Agreement shall apply to all Confidential Information during the Term of this
Agreement and for a period of five (5) years thereafter, provided, however, that
Medarex recognizes that by reason of Northwest's status as an exclusive licensee
pursuant to the grant under Section 2.1, Northwest has an interest in Medarex's
retention in confidence of certain information of Medarex. Accordingly, Medarex
shall, and shall cause its officers, directors, employees and agents to, keep
completely confidential, and not publish or otherwise disclose, and not use
directly or indirectly for any purpose, any information relating solely to the
Unilateral Products, except to the extent (a) such information is in the public
domain through no fault of Medarex, its Affiliates or any of their respective
officers, directors, employees and agents, (b) such disclosure or use would be
permitted under Section 6.4 of the Collaboration Agreement, or (c) such
disclosure or use is otherwise expressly permitted by the terms of this
Agreement or is reasonably necessary for the performance of this Agreement. For
clarification, the disclosure by Medarex to Northwest or by Northwest to Medarex
of certain information of Medarex relating solely to the Unilateral Products
shall not cause such information to cease to be subject to the confidentiality
provisions of Sections 6.1 through 6.4 of the Collaboration Agreement.

        SECTION 4.2 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.

        SECTION 4.3 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

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<PAGE>   67

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 4.4 PUBLICATIONS. At least sixty (60) days prior to submission
for publication, presentation or other public disclosure by Northwest or any of
its Affiliates of any material pertaining to or resulting from the Medarex
Technology, Northwest shall provide to Medarex a draft of such material for its
review and comment. No publication or presentation with respect to the Medarex
Technology shall be made unless and until Medarex's comments on the proposed
publication or presentation have been addressed and changes have been agreed
upon and any information determined by Medarex to be Confidential Information
has been removed. If requested in writing by Medarex, Northwest 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 5 -
                              INTELLECTUAL PROPERTY

        SECTION 5.1 INTELLECTUAL PROPERTY OWNERSHIP.

            5.1.1 OWNERSHIP OF TECHNOLOGY. Subject to Section 5.1.2 and the
license grants to Northwest under Article 2, as between the Parties, each Party
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 such Party (or its Affiliates or its
licensees or sublicensees (other than the other Party 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 Joint 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 such Party, its Affiliates or its licensees or sublicensees
(other than such other Party); and (c) other Technology of such Party.

            5.1.2 OWNERSHIP OF MICE-RELATED TECHNOLOGY. Subject to the license
grants to Northwest under Article 2, 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

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<PAGE>   68

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 Section 2.1 permit Northwest to use Mice
Materials and Mice-Related Technology solely for the Exploitation of Unilateral
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.

            5.1.3 OWNERSHIP OF JOINT TECHNOLOGY. Subject to Section 5.1.2 and
the license grants under Article 3, the Parties shall each own an equal,
undivided interest in any and all (a) Information and Inventions, conceived,
discovered, developed or otherwise made, as necessary to establish authorship,
inventorship or ownership under Applicable Law, jointly by or on behalf of
Northwest (or its Affiliates or, to the extent permitted, its sublicensees), on
the one hand, and Medarex (or its Affiliates or, to the extent permitted, its
sublicensees), on the other hand, in connection with the work conducted under or
in connection with this Agreement, whether or not patented or patentable, but
excluding any Mice Materials or Mice-Related Technology, and (b) patents
(including (x) all patents and patent applications, (y) any substitutions,
divisions, continuations, continuations-in-part, reissues, renewals,
registrations, confirmations, reexaminations, 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) (the, "JOINT PATENTS") and other
intellectual property rights with respect thereto (collectively, the "JOINT
TECHNOLOGY"); provided, however, that, except as otherwise expressly provided
herein, neither a Party nor any of its Affiliates, licensees or sublicensees
shall, directly or indirectly, Exploit any Joint Technology or other such
intellectual property rights without the consent of the other Party, not to be
unreasonably withheld or delayed. 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 Joint Technology.

            5.1.4 OWNERSHIP OF PRODUCT TRADEMARKS. Northwest shall own all
right, title and interest in and to each Product Trademark with respect to a
Unilateral Product. Medarex hereby assigns all of its right, title and interest
in and to any Product Trademark to Northwest to the extent that such Product
Trademark relates solely to the Unilateral Products.

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<PAGE>   69

            5.1.5 OWNERSHIP OF REGULATORY DOCUMENTATION. Northwest shall own all
right, title and interest in and to all Regulatory Documentation that relates
solely to the Unilateral Products. Medarex hereby assigns to Northwest such of
its right, title and interest in and to such Regulatory Documentation (but
excluding any Regulatory Documentation comprising Production Process Technology,
including any drug master file) as is necessary to vest ownership of such
Regulatory Documentation in Northwest as provided in the immediately preceding
sentence. Notwithstanding the ownership of any Regulatory Documentation, each
Party shall have the right to use and reference any of the Regulatory
Documentation in connection with the Exploitation of Unilateral Products as
provided in this Agreement and Collaboration Products as provided in the
Collaboration Agreement.

            5.1.6 NOTICES. To the extent that Northwest has the right to (a)
assign, transfer, convey or otherwise encumber any right, title or interest in
or to any Medarex Technology, Joint Technology or Collaboration Technology, (b)
grant any license or other right, title or interest in or to any Medarex
Technology, Joint Technology or Collaboration Technology, or (c) agree to or
otherwise become bound by any covenant not to sue for any infringement, misuse
or other action or inaction with respect to any Medarex Technology, Joint
Technology or Collaboration Technology, in each case Northwest shall not do so,
directly or indirectly, expressly or by implication, by action or omission or
otherwise without providing Medarex with at least sixty (60) days advance
written notice thereof.

        SECTION 5.2 PROSECUTION OF PATENTS AND TRADEMARKS.

            5.2.1 MEDAREX PATENTS. As between the Parties, Medarex shall,
subject to Section 5.2.5, have the sole right, at its cost and expense, to
obtain, prosecute and maintain throughout the world the Medarex Patents,
provided, however, that Northwest shall reimburse Medarex for one hundred
percent (100%) of the reasonable out-of-pocket costs incurred by Medarex for
filing, prosecuting and maintaining such Patents to the extent that they claim
or cover (x) as a composition of matter, a Unilateral Product or any active
ingredient in such Unilateral Product or (y) the use of any such Unilateral
Product or ingredient. Northwest shall, and shall cause its Affiliates,
licensees and sublicensees, as applicable, to, cooperate fully with Medarex in
the preparation, filing, prosecution, and maintenance of Medarex's Patents. 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 Medarex to file, prosecute, and maintain its Patents
in any country; and (b) promptly informing Medarex of matters that may affect
the preparation, filing, prosecution, or maintenance of any such Patents.

            5.2.2 JOINT PATENTS. The Parties shall cooperate with one another
with respect to the filing, prosecution and maintenance of all Joint 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 associated with the filing, prosecution (including any
interferences, reissue proceedings and reexaminations) and maintenance of all
Joint Patents If a Party elects not to pursue the filing, prosecution or
maintenance of a Joint Patent in a particular country, or to take any

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<PAGE>   70

other action with respect to Joint Technology 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 Joint
Technology 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 the right, but not
the obligation, to pursue the filing or registration, or support the continued
prosecution or maintenance, of such Patent 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 2, promptly release or assign
to such other Party, without compensation, all right, title and interest in and
to such Patent in such country.

            5.2.3 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.

        SECTION 5.3 ENFORCEMENT OF PATENTS AND TRADEMARKS.

            5.3.1 RIGHTS AND PROCEDURES. If either Party determines that any
Technology (which for purposes of this Agreement shall be deemed to include
Joint Technology) of the other Party 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 such 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.

                (a) JOINT TECHNOLOGY. With respect to Joint Technology, the
Parties shall have the first right to jointly remove such infringement using
commercially appropriate steps, including the filing of an infringement suit or
taking other similar action. Each Party shall be responsible for half of the
reasonable and verifiable costs and expenses incurred in connection with such
action In the event the Parties fail to jointly take commercially appropriate
steps to remove any infringement of any Joint Technology within ninety (90) days
following notice of such infringement, or a Party earlier notifies the other in
writing of its intent not to take such steps, the Party pursuing the filing,
prosecution or maintenance of a Patent comprising such Joint Technology (the
"PROSECUTING PARTY") shall have the right to do so at its own expense, or, in
the event such Party declines, the other Party shall have the right to do so at
its own expense;

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<PAGE>   71

provided, however, that if the Parties have jointly commenced negotiations with
an alleged infringer for discontinuance of such infringement within such ninety
(90) day period, the Parties shall have an additional ninety (90) days to
conclude their negotiations before a Party unilaterally may bring suit for such
infringement.

                (b) MEDAREX TECHNOLOGY. With respect to Medarex Technology that
is not Mice-Related Technology or Production Process Technology, Medarex shall
have the first right, but not the obligation, to remove such infringement at its
sole cost and expense. In the event Medarex fails to take commercially
appropriate steps to remove any infringement of such Technology within ninety
(90) days following notice of such infringement, or earlier notifies Northwest
in writing of its intent not to take such steps, Northwest shall have the right
to do so at its sole cost and expense; provided, however, that if Medarex has
commenced negotiations with an alleged infringer for discontinuance of such
infringement within such ninety (90) day period, Medarex shall have an
additional ninety (90) days to conclude its negotiations before Northwest may
bring suit for such infringement; and provided further that Northwest shall
reimburse Medarex for one hundred percent (100%) of the reasonable out-of-pocket
costs incurred by Medarex with respect to the removal of any such infringement
with respect to any Unilateral Product.

                (c) MICE-RELATED AND PRODUCTION PROCESS TECHNOLOGY. With respect
to Mice-Related Technology or Medarex's Production Process Technology, Medarex
shall have the sole right, but not the obligation, to remove such infringement
at its sole cost and expense; provided, however, that Northwest shall reimburse
Medarex for one hundred percent (100%) of the reasonable out-of-pocket costs
incurred by Medarex with respect to the removal of any such infringement with
respect to any Unilateral Product.

            5.3.2 COOPERATION. The Party not enforcing the applicable Technology
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.

            5.3.3 RECOVERY. Any amounts recovered by a Party pursuant to Section
5.3.1, 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 Unilateral 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 Unilateral Product.

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<PAGE>   72

        SECTION 5.4 POTENTIAL THIRD PARTY RIGHTS.

            5.4.1 THIRD PARTY LICENSES. If (a) in the opinion of outside patent
counsel to Northwest, Northwest, or any of its Affiliates, licensees or
permitted sublicensees, cannot Exploit a Unilateral Product in a country in the
Territory without infringing one or more Patents that have issued to a Third
Party in such country, or (b) 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 Unilateral 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 Northwest
cannot Exploit such Unilateral Product in such country without infringing the
Patent or other proprietary rights of such Third Party, then, in either case,
Northwest shall have the first right, but not the obligation to negotiate and to
obtain a license from such Third Party as necessary for the Exploitation of any
Unilateral Products hereunder in such country; provided, however, that Medarex
shall have the sole right to seek any such license with respect to Mice-Related
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 any of its Affiliates and permitted
sublicensees, to Exploit the Unilateral Products as provided hereunder in such
country Northwest shall be solely responsible for one hundred percent (100%) of
all royalty and other obligations with respect to the Exploitation of Unilateral
Products.

            5.4.2 THIRD PARTY LITIGATION. 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
Unilateral 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. Northwest shall direct and control, at
its sole cost and expense, any Infringement Suit with respect to the Unilateral
Products (excluding any Infringement Suit with respect to the Mice-Related
Technology as to which Medarex shall retain the exclusive right to direct and
control); provided, however, that Northwest shall not cease to defend, settle or
otherwise dispose of a suit with respect to any intellectual property of Medarex
without Medarex's prior written consent. With respect to the Joint Patents, the
Parties shall each bear fifty percent (50%) of any costs and expenses of such
defense, and, with respect to the Exploitation of Unilateral Products, Northwest
shall bear one hundred percent (100%) of those costs and expenses.

            5.4.3 RETAINED RIGHTS. Nothing in this Section 5.4 shall prevent
Northwest, 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 under this Agreement.

                                       16
<PAGE>   73

        SECTION 5.5 EXCHANGE OF KNOW-HOW.

            5.5.1 INFORMATION DISCLOSURE. Medarex shall, and shall cause its
Affiliates to, without additional compensation and at its sole expense, disclose
and make available to Northwest, in whatever form Northwest may reasonably
request, all Regulatory Documentation, all of its other Know-How, all
Information and Inventions included in the Collaboration Technology and the
Joint Technology and any other Information and Inventions that are reasonably
necessary to Exploit Antibody Products with respect to each Unilateral Target
immediately after such Unilateral Target is first designated as such 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.

            5.5.2 COOPERATION. Medarex shall cooperate with any and all
reasonable requests for assistance from Northwest, at Northwest's sole cost and
expense, including by making its employees, consultants and other scientific
staff available upon reasonable notice during normal business hours at Medarex's
place of business to consult with Northwest on issues arising with respect to
the Medarex Technology in connection with the research, development,
commercialization or other Exploitation of Unilateral Products.

            5.5.3 BIOLOGICAL MATERIALS. For purposes of facilitating the conduct
of the development activities with respect to the Unilateral Products, Medarex
shall provide to Northwest the Biological Materials, but not Mice Materials,
necessary to perform such activities. The Parties agree that: (a) all such
Biological Materials provided by Medarex to Northwest and any Biological
Material produced against or with, or derived from, such Biological Materials
shall be used solely for the development and commercialization of Unilateral
Products, and in material compliance with all Applicable Law; (b) all such
Biological Materials shall be provided without any warranties, express or
implied; (c) Medarex 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 Medarex to Northwest shall not be made available by Northwest to any Third
Party, unless the prior written consent of Medarex is first obtained; and (e)
subject to the license grants in Article 2 and other provisions in this
Agreement, all right, title and interest in and to the Mice Materials and the
Mice-Related Technology shall be, and remain, vested in Medarex.

            5.5.4 REGULATORY RECORDS. Northwest shall maintain, or cause to be
maintained, records of its respective research, development, manufacturing and
commercialization activities for the Unilateral Products, 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. Medarex shall have the
right, during normal business hours and upon reasonable notice,

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<PAGE>   74
to inspect and copy any such records Medarex shall have an irrevocable,
perpetual right to use and reference such Regulatory Documentation for all
purposes.

           5.5.5 PRODUCTION PROCESS TECHNOLOGY. Notwithstanding anything to the
contrary in this Section 5.5 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 Unilateral Products. 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 6 -
                              TERM AND TERMINATION

        SECTION 6.1 TERM. The term of this Agreement (the "TERM") shall commence
upon the Effective Date and shall continue in effect until such time as there is
no longer any Unilateral Product being Exploited hereunder, unless terminated at
an earlier date in accordance with the terms and conditions set forth in this
Article 6.

        SECTION 6.2 TERMINATION OF AGREEMENT FOR MATERIAL BREACH. 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
notice specifying the nature of the default, requiring the defaulting Party to
make good or otherwise cure such default, and stating its intention to terminate
if such default is not cured. If such default is not cured within thirty (30)
days after the receipt of such notice (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 ninety
(90) days after the receipt of such notice), the Parties not in default shall be
entitled, 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 terminate this Agreement in its entirety.

        SECTION 6.3 TERMINATION OF RIGHTS WITH RESPECT TO UNILATERAL PRODUCTS
UPON MATERIAL BREACH. Any material failure by Northwest to comply with any of
its material obligations contained herein with respect to a Unilateral Product
shall entitle Medarex to give to Northwest notice specifying the nature of the
default, requiring Northwest to make good or otherwise cure such default, and
stating its intention to convert such Unilateral Product to a Unilateral Product
of Medarex under the Unilateral Development and Commercialization Agreement
attached to the Collaboration Agreement as Appendix D-2 if such default is not
cured. If such default is not cured within thirty (30) days after the receipt of
such notice (or, if such default cannot be cured within such thirty (30)-day
period, if Northwest 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 ninety (90) days after the receipt of such notice),
Medarex shall be entitled, on written notice to Northwest, to convert such
Unilateral

                                       18
<PAGE>   75

Product to a Unilateral Product of Medarex, whereupon each shall be subject to
their respective rights and obligations under the Unilateral Development and
Commercialization Agreement attached to the Collaboration Agreement as Appendix
D-2, including the royalty obligations set forth therein (provided that the
royalty rate owed by Medarex pursuant to such Unilateral Development and
Commercialization Agreement shall equal the royalty rate that Northwest would
have owed Medarex had it not defaulted) and the indemnification obligations.

        SECTION 6.4 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 6.5 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

        SECTION 6.6 CONSEQUENCES OF EXPIRATION OR TERMINATION.

           6.6.1 LICENSES. Upon expiration of the full term of this Agreement in
accordance with Section 6.1 and the payment of all amounts due under Section
3.1, the licenses granted by Medarex to Northwest hereunder shall be deemed
fully-paid up.

           6.6.2 RETURN OF INFORMATION. Upon expiration of this Agreement
pursuant to Section 6.1 or upon termination of this Agreement in its entirety by
either Party pursuant to this Article 6, Northwest, at the request of Medarex,
shall return all data, files, records and other materials in its possession or
control relating to Medarex's

                                       19
<PAGE>   76

Technology, or containing or comprising Medarex's Information and Inventions or
other Confidential Information and to which Northwest does not retain rights
hereunder (except one copy of which may be retained for archival purposes).

        SECTION 6.7 ACCRUED RIGHTS; SURVIVING OBLIGATIONS.

           6.7.1 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.

           6.7.2 SURVIVAL. Articles 3 (with respect to obligations arising prior
to expiration or termination), 4 and 7, and Sections 2.2.5, 2.3, 5.1, 5.2,
5.5.3, 5.5.4, 6.5, 6.6, 9.4, 9.5 and 9.6 of this Agreement and this Section 6.7
shall survive expiration or termination of this Agreement for any reason.

                                   ARTICLE 7 -
                         INDEMNIFICATION AND INSURANCE

        SECTION 7.1 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, 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 to connection with any breach by Medarex of this
Agreement, except for those Losses for which Northwest has an obligation to
indemnify Medarex and its Affiliates pursuant to Section 7.2, as to which
Losses each Party shall indemnify the other to the extent of their respective
liability for the Losses.

        SECTION 7.2 INDEMNIFICATION OF MEDAREX. Northwest shall indemnify
Medarex and its Affiliates, 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
Northwest of this Agreement, (b) the development, manufacture or
commercialization of a Unilateral Product by or on behalf of Northwest or its
Affiliates or sublicensees, or (c) 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 7.1, as to
which Losses each Party shall indemnify the other to the extent of their
respective liability for the Losses.

        SECTION 7.3 INDEMNIFICATION PROCEDURE.

        7.3.1 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

                                       20
<PAGE>   77
for indemnification under Section 7.1 or Section 7.2, 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").

        7.3.2 THIRD PARTY CLAIMS. Subject to Section 5.4, the obligations of an
indemnifying Party under this Article 7 with respect to Losses arising from
claims of any Third Party that are subject to indemnification as provided for in
Section 7.1 or 7.2 ( a "THIRD PARTY CLAIM") shall be governed by and be
contingent upon the following additional terms and conditions

           (a) CONTROL OF DEFENSE. 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. 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 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. 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
7.3.2(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

                                       21
<PAGE>   78

counsel in accordance with Section 7.3.2(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 Patty has
assumed the defense of the Third Party Claim in accordance with Section
7.3.2(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
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 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 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 7.4 INSURANCE. Northwest shall have and maintain such types and
amounts of liability insurance as is normal and customary in the industry
generally for

                                       22
<PAGE>   79

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 8 -
                         REPRESENTATIONS AND WARRANTIES

        SECTION 8.1 REPRESENTATIONS, WARRANTIES AND COVENANTS. Each Party is
entering into this Agreement in reliance upon the representations, warranties
and covenants of the other Party set forth in Sections 10.1, 10.2 and 10.3 of
the Collaboration Agreement.

        Section 8.2 DISCLAIMER OF WARRANTY. EXCEPT FOR THE EXPRESS WARRANTIES
SET FORTH IN SECTIONS 10.1, 10.2 AND 10.3 OF THE COLLABORATION AGREEMENT,
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 9 -
                                 MISCELLANEOUS

        SECTION 9.1 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.

        SECTION 9.2 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

                                       23
<PAGE>   80

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 9.3 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 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 9.4 DISPUTES. Any dispute that may arise relating to this
Agreement 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. 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, then either Party shall have the right to litigate such dispute in
accordance with Section 9.5 or to pursue such other dispute resolution mechanism
as the Parties may agree.

        SECTION 9.5 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. The Parties hereby irrevocably
and unconditionally consent to the exclusive jurisdiction of the courts of the
State of Washington located in Seattle and the United States District Court for
the district within which Seattle is located 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

                                       24
<PAGE>   81

relating to this Agreement in the courts of the State of Washington located in
Seattle or the United States District Court for the district within which
Seattle is located, 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 9.6 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.
                               21270 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

        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

                                       25
<PAGE>   82

                               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 9.6 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 9.7 ENTIRE AGREEMENT; MODIFICATIONS. This Agreement, together,
with the Collaboration Agreement, sets forth and constitutes the entire
agreement and understanding between the Parties with respect to the subject
matter hereof and thereof and all prior agreements, understanding, promises and
representations, whether written or oral, with respect thereto are superseded
hereby and thereby. Each Party confirms that it is not relying on any
representations or warranties of the other Party except as specifically set
forth herein or therein. 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 9.8 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 9.9 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 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 9.10 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 9.11 NO BENEFIT TO THIRD PARTIES. The representations,
warranties, covenants and agreements set forth in this Agreement are for the
sole benefit of the

                                       26
<PAGE>   83

Parties hereto and their successors and permitted assigns, and they shall not be
construed as conferring any rights on any other parties

        SECTION 9.12 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 9.13 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 9.14 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 9.15 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
Patty hereto.

             [The remainder of this page intentionally left blank.]

                                       27
<PAGE>   84

        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: /s/ DONALD L. DRAKEMAN                By: /s/  DANIEL O. WILDS
   ---------------------------------         ---------------------------------
Name: Donald L. Drakeman                  Name: Daniel O. Wilds
      ------------------------------            ------------------------------
Title: President and CEO                  Title: President & CEO
       -----------------------------             -----------------------------

Signature Page of Appendix D-1 Unilateral Development and Commercialization
Agreement

                                       28
<PAGE>   85

                                   APPENDIX A

              COLLABORATION ANTIBODIES AND COLLABORATION PRODUCTS

        This Appendix to the UNILATERAL DEVELOPMENT AND COMMERCIALIZATION
AGREEMENT ("AGREEMENT") effective as of April 24, 2001, by and between NORTHWEST
BIOTHERAPEUTICS, INC. ("NORTHWEST") and MEDAREX, INC., on behalf of itself and
its wholly owned subsidiary, GENPHARM INTERNATIONAL, INC., (collectively,
"MEDAREX") sets forth the Collaboration Antibodies with respect to the
applicable Collaboration Targets.

        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.

                                       1
<PAGE>   86

                                  APPENDIX D-2

                             UNILATERAL DEVELOPMENT
                         AND COMMERCIALIZATION AGREEMENT

        THIS UNILATERAL DEVELOPMENT AND COMMERCIALIZATION 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, Northwest and Medarex have entered into that certain
Collaboration Agreement, dated as of the date hereof (the "COLLABORATION
AGREEMENT");

        WHEREAS, the Parties have agreed that in the event Northwest elects not
to proceed with the development and commercialization of certain Collaboration
Targets and Medarex notifies Northwest of its election to proceed unilaterally
with such development and commercialization in accordance with Section 5.1.2 of
the Collaboration Agreement, that Medarex shall have the right to do so in
accordance with the terms set forth below; and

        WHEREAS, the Parties have agreed that in the event Northwest fails to
comply with any of its material obligations contained in the Collaboration
Agreement with respect to a Collaboration Product, Medarex shall have the right
to convert such Collaboration Product into a Unilateral Product in accordance
with Section 8.2 of the Collaboration Agreement and proceed unilaterally with
the development and commercialization of such Unilateral Product in accordance
with 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 -
                  UNILATERAL DEVELOPMENT AND COMMERCIALIZATION

        SECTION 1.1 DEFINITIONS. Any capitalized term used in this Agreement not
otherwise defined herein shall have the meaning set forth in the Collaboration
Agreement.

                                       1
<PAGE>   87

        SECTION 1.2 UNILATERAL TARGETS, ANTIBODIES AND PRODUCTS. In the event
that Medarex provides Northwest with (a) an Election Notice with respect to a
Collaboration Target pursuant to Section 5.1.2 of the Collaboration Agreement,
or (b) written notice of Northwest's failure to cure a default to any of its
material obligations with respect to a Collaboration Product with respect to a
Collaboration Target pursuant to Section 8.2 of the Collaboration Agreement,
Appendix A hereto shall be amended to include such Collaboration Target and any
Collaboration Antibodies with respect thereto, which Collaboration Targets and
Collaboration Antibodies shall be referred to herein as "Unilateral Targets" and
"Unilateral Antibodies," respectively. Medarex shall have the exclusive right to
Exploit any and ail Antibody Products with respect to the Unilateral Targets
(each such Antibody Product, a "UNILATERAL PRODUCT"), including any
Collaboration Products with respect to such Unilateral Targets developed or
commercialized pursuant to the Collaboration Agreement or any other Antibody
Products containing or comprising Unilateral Antibodies.

        SECTION 1.3 RIGHTS AND OBLIGATIONS OF THE PARTIES WITH RESPECT TO
UNILATERAL PRODUCTS. Except as otherwise expressly provided herein, Medarex
shall be solely responsible for all costs and expenses in connection with the
development and commercialization of the Unilateral Products, provided, however,
that Northwest shall be responsible for all budgeted costs and expenses
associated with the research and development activities with respect to the
Unilateral Products that Northwest has committed to in the applicable Project
Budget as necessary to complete that phase (e.g., toxicology studies in support
of an IND or Phase I, Phase II or Phase III) of research and development that
was under way when Northwest Opted-Out of such Unilateral Products. By way of
clarification, Medarex shall be responsible, at its sole cost, for all milestone
and royalty payments, license fees and other payments owed to Third Parties,
whether by Medarex, Northwest or their respective Affiliates, in connection
with the development and commercialization of Unilateral Products, including any
payments owed by Medarex and its Affiliates under the Biosite Agreement or the
MRC Agreement. The Parties shall work together to ensure a smooth and orderly
transition of the Unilateral Products to Medarex, including the assignment of
any contracts with respect to the Exploitation of such Unilateral Products to
Medarex, and the assumption by Medarex of any obligations thereunder. Except for
the obligations provided for in this Section 1.3, Northwest shall lave (a) no
further financial obligation to support or otherwise fund any additional efforts
in respect of such Unilateral Products, and (b) no obligation, responsibility,
or authority regarding such additional efforts in respect of such Unilateral
Products.

        SECTION 1.4 PERFORMANCE OF MEDAREX. Medarex shall use Commercially
Reasonable Efforts to develop and commercialize one or more Unilateral Products
with respect to each Unilateral Target. Such activities shall be performed in
good scientific manner, and in compliance in all material respects with all
Applicable Law, including current good laboratory practices and good clinical
practices (including compliance with such practices and guidelines necessary to
allow the results of such activities to support INDs, BLAs and other Regulatory
Approvals), as applicable. Medarex shall have the right, subject to the
obligations set forth in this Section 1.4, to license to Third Parties rights
with respect to the development or commercialization of a Unilateral Product in
its sole discretion; provided that any such Third Party enters into a written
agreement with

                                       2
<PAGE>   88

Medarex to indemnify Northwest and its Affiliates to the extent provided in
Article 7, and to be bound by the provisions of Articles 4 and 5 and Section 13;
provided, however, that any sublicense with respect to the Northwest
Technology shall be governed by the procedures set forth in Section 2.3.

        SECTION 1.5 MEDAREX REPORTS. Medarex shall provide an annual written
progress report to Northwest describing the development and commercialization
activities with respect to each of its Unilateral Products in sufficient detail
to enable Northwest to determine whether Medarex is using Commercially
Reasonable Efforts with respect thereto.

        SECTION 1.6 COMMUNICATIONS AND FILINGS WITH REGULATORY AUTHORITIES.
Medarex shall be responsible for all communications and filings with the
Regulatory Authorities with respect to each of its Unilateral Products.

        SECTION 1.7 OPT-OUT BY MEDAREX. If, at any time, Medarex decides to
cease development or commercialization of all Unilateral Products with respect
to a Unilateral Target, either alone or in collaboration with or through a Third
Party, it shall give prompt written notice thereof to Northwest, which notice
shall describe in reasonable detail the reasons for such decision. Medarex
shall, for a period of thirty (30) days after notice to Northwest with respect
thereto, furnish Northwest with such information and materials as Northwest may
reasonably request so as to determine whether it wishes to proceed with the
unilateral development and commercialization of such Unilateral Products. Upon
its receipt of all of such information and materials, Northwest shall, for a
period of thirty (30) days, have the right to elect to proceed unilaterally with
the development and commercialization of such Unilateral Products. Upon such
election, Appendix A shall be amended to delete such Unilateral Target and any
Unilateral Antibodies with respect thereto, and the Unilateral Development and
Commercialization Agreement set forth in Appendix D-1 to the Collaboration
Agreement shall be automatically amended to include such Unilateral Target and
such Unilateral Antibodies, provided that the royalty rate with respect to such
Unilateral Products shall be the rate that Medarex would have owed to Northwest
had it not elected to cease development or commercialization of such Unilateral
Products. By way of clarification, Medarex shall have the right to pursue one
or more Unilateral Products with respect to a Unilateral Target and any
decision to cease Exploiting one in favor of another shall not be subject to
this Section 1.7 for so long as Medarex is using Commercially Reasonable Efforts
to develop and commercialize at least one Unilateral Product with respect to
such Unilateral Target.

                                   ARTICLE 2 -
                                 LICENSE GRANTS

        SECTION 2.1 NORTHWEST GRANT. Subject to Section 2.2 and the other terms
and conditions of this Agreement, Northwest hereby grants to Medarex and its
Affiliates, with respect to each Unilateral Product, an exclusive (even as to
Northwest and its Affiliates), royalty-bearing license, with the right to
sublicense solely as provided in Section 2.3, under the Northwest Technology,
the Collaboration Technology and the Joint

                                       3
<PAGE>   89

Technology to Exploit such Unilateral Products in the Territory in accordance
with this Agreement.

        SECTION 2.2 EXCLUSIVITY, RESERVED RIGHTS AND PRE-EXISTING GRANTS.

            2.2.1 ANTIGEN EXCLUSIVITY. Subject to Sections 2.2.2 and 2.2.4, the
Parties acknowledge and agree 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 Unilateral Target listed on Appendix A other than the
Unilateral Products as provided to this Agreement.

            2.2.2 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
Antibody Products containing or comprising Unilateral Antibodies) with respect
to Antigens, including Unilateral 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").

            2.2.3 RETAINED RIGHTS.

                (a) OTHER ANTIGENS. Notwithstanding anything in this Agreement
to the contrary, Medarex shall have and retain the right to (i) enter into
collaborations with, and to grant licenses and other rights under the Medarex
Technology to, Third Parties to Exploit Antibody Products with respect to
Antigens other than Unilateral Targets, and/or (ii) independently Exploit
Antibody Products with respect to Antigens other than Unilateral Targets.

                (b) NON-ANTIBODY PRODUCTS. Notwithstanding anything in this
Agreement to the contrary, each Party shall have and retain the right to (i)
enter into collaborations with, and to grant licenses and other rights under its
respective Technology (other than Joint Technology and Collaboration Technology,
which shall be governed by Section 5.1.3 and the Collaboration Agreement,
respectively) to, Third Parties to Exploit products other than antibody-based
products with respect to Unilateral Targets, and/or (ii) independently Exploit
products other than antibody-based products with respect to Unilateral Targets.

            SECTION 2.3 SUBLICENSES. Medarex shall have the right to grant to
Third Parties sublicenses under the license granted in Section 2.1 only with the
prior written consent of Northwest, not to be unreasonably withheld or delayed,
which approval shall be deemed to be granted with respect to a sublicense if
Northwest fails, within ten (10) days of its

                                       4
<PAGE>   90

receipt of a written notice from Medarex setting forth in reasonable detail the
nature of such sublicense and the identity of the sublicensee, to notify Medarex
in writing that it withholds its consent to such sublicense, provided, however,
that the grant of any such sublicense shall not relieve Medarex of its
obligations under this Agreement.

        SECTION 2.4 LICENSE LIMITATIONS. Medarex hereby covenants to Northwest
that neither Medarex nor any of its Affiliates, licensees or sublicensees shall
use or practice the Northwest Technology, directly or indirectly, on behalf of
itself or any other party, for any purpose other than as permitted under Section
2.1 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 Unilateral Product
as provided hereunder or a Collaboration Produc? as provided in the
Collaboration Agreement.

        SECTION 2.5 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, in each case except as expressly provided in Section 2.1
of this Agreement and Section 3.1 of the Collaboration Agreement.

                                   ARTICLE 3 -
                              FINANCIAL PROVISIONS

        SECTION 3.1 MILESTONE PAYMENTS. Within thirty (30) days of the
achievement of the following milestones, on a Unilateral Target-by-Unilateral
Target basis, for Unilateral Products with respect to each Unilateral Target,
Medarex shall pay to Northwest the specified milestone payments, each of which
shall be nonrefundable:

<TABLE>
<CAPTION>
                        1ST UNILATERAL        2ND UNILATERAL         EACH ADDITIONAL
                        PRODUCT WITH          PRODUCT WITH           UNILATERAL PRODUCT
                        RESPECT TO A          RESPECT TO A           WITH RESPECT TO A
MILESTONES              UNILATERAL TARGET     UNILATERAL TARGET      UNILATERAL TARGET
----------              -----------------     -----------------      -----------------
<S>                      <C>                   <C>                   <C>
IND Filing               $    500,000          $    500,000          $    500,000

Commencement of
Phase II                 $  1,000,000          $  1,000,000          $  1,000,000

Commencement of
Phase III                $  1,500,000          $  1,500,000          $  1,500,000

BLA Filing or
equivalent in a
Major Market             $  2,000,000          $  2,000,000          $  2,000,000

Upon approval of
first BLA or
equivalent in a
Major Market             $  2,000,000          $  1,500,000          $  1,000,000

Upon approval of
BLA or equivalent
in a second Major
Market                   $  1,500,000          $  1,000,000          $    500,000
</TABLE>

                                       5
<PAGE>   91

        SECTION 3.2 ROYALTIES

            3.2.1 OBLIGATION. With respect to each Unilateral Product, Medarex
shall pay Northwest royalties based upon the annual worldwide Net Sales (on a
calendar year basis) for such Unilateral Product. The royalty rates shall be
determined on a Unilateral Target-by-Unilateral Target basis based on the
aggregate Net Sales of each Unilateral Product with respect to such Unilateral
Target and on the stage of development and commercialization that the first
Collaboration Product with respect to such Unilateral Target had achieved when
such Collaboration Target was designated as a Unilateral Target.

            3.2.2 RATES. The royalty rates for each Unilateral Product (a) for
which Northwest Opted-Out pursuant to Section 5.1.1 of the Collaboration
Agreement, or (b) which was converted from a Collaboration Product pursuant to
Section 8.2 of the Collaboration Agreement upon Northwest's default in any of
its material obligations shall be as follows:

<TABLE>
<CAPTION>
               OPT-OUT OR TERMINATION PHASE                          ROYALTY
               ----------------------------                          -------
<S>                                                                  <C>
             Prior to the first Phase I Completion in a Major
             Market                                                   2%

             Post-Phase I Completion to the first Phase II
             Completion in a Major Market                             3%

             Post-Phase II Completion in a Major Market               5%
</TABLE>

If an Opt-Out (as opposed to a termination event) occurs within thirty (30) days
after the end of a phase, the royalty rate shall be calculated based on such
recently expired PHASE.

            3.2.3 DEFINITIONS. For purposes of this Agreement, the following
definitions shall apply:

                (a) "MAJOR MARKET" shall mean each of Japan, the United States,
the United Kingdom, France, Germany and the European Union as a whole.

                (b) "PHASE I" shall mean a human clinical trial, the principal
purpose of which is a preliminary determination of safety in healthy individuals
or patients as required in 21 C.F.R. Section 312, or a similar clinical study
prescribed by the Regulatory Authorities in a Major Market other than the United
States.

                (c) "PHASE I COMPLETION" shall mean, with respect to a
Unilateral Target, the completion of a complete data package from (i) a Phase I
study, which data package is sufficient to support the commencement of Phase II
studies in support of the filing of an approvable BLA in a Major Market, or (ii)
in the event that Phase I and Phase II are combined, the first study in support
of the filing of an approvable BLA in a Major

                                       6
<PAGE>   92

Market that enrolled at least twenty (20) subjects, in either case for the first
Collaboration Product with respect to such Collaboration Target.

                (d) "PHASE II" shall mean a human clinical trial, for which a
primary endpoint is a preliminary determination of efficacy or dose ranges in
patients with the disease target being studied as required in 21 C.F.R. Section
312, or a similar clinical study prescribed by the Regulatory Authorities in a
Major Market other than the United States. Any well-controlled study intended to
provide the substantial evidence of efficacy necessary to support the filing of
an approvable BLA (such as a combined Phase II/Phase III study, or any Phase III
study in lieu of a Phase II study) (a "Pivotal Study") shall automatically be
deemed to have reached Phase II status A. Phase II study shall be deemed to have
commenced when the first subject in such study has been enrolled.

                (e) PHASE II COMPLETION" shall mean, with respect to a
Unilateral Target, the completion of a complete data package from (a) Phase II
studies, which data package is sufficient to support the commencement of Phase
III studies in support of the filing of an approvable BLA in a Major Market, or
(b) in the event that Phase II and III Studies are combined, the first such
study in support of the filing of an approvable BLA in a Major Market that
enrolled at least forty (40) patients with the disease target being studied, in
either case for the first Collaboration Product with respect to such
Collaboration Target.

                (f) "PHASE III" shall mean a human clinical trial, the principal
purpose of which is to establish safety and efficacy in patients with the
disease target being studied as required in 21 C.F.R. Section 312, or similar
clinical study prescribed by the Regulatory Authorities in a Major Market other
than the United States. A Phase III study shall also include any other human
clinical trial intended as a Pivotal Study, whether or not such study is a
traditional Phase III study. A Phase III study shall be deemed to have commenced
when the first patient has been enrolled in a Pivotal Study.

                (g) "PHASE III COMPLETION" shall mean, with respect to a
Unilateral Target, the completion of a data package for a Phase III study with
respect to the first Unilateral Product with respect to such Unilateral Target,
which data package is sufficient to support the filing of an approvable BLA for
such Unilateral Product in a Major Market.

        SECTION 3.3 ROYALTY TERM. Medarex's royalty obligations under Section
3.2.2 shall terminate, on a country-by-country basis, with respect to each
Unilateral Product with respect to a Unilateral Target, on the later to occur of
(a) the tenth (10th) anniversary of the first sale for use or consumption by
the general public of such Unilateral Product in a country after Regulatory
Approval has been obtained for such Unilateral Product in such country (the
"FIRST COMMERCIAL SALE"), and (b) the expiration date in such country of the
last to expire of any issued Joint Patent or Northwest Patent that includes at
least one Valid Claim covering the Exploitation of such Unilateral Product in
such country. Upon termination of the royalty obligations of Medarex under this
Section 3.3 in a country, the license grants to Medarex in Section 2.1 shall
become fully-paid with respect to such country.

                                       7
<PAGE>   93

        SECTION 3.4 ROYALTY PAYMENTS. Running royalties shall be payable on a
quarterly basis, within forty-five (45) days after the end of each calendar
quarter, based upon the Net Sales during such calendar quarter, commencing with
the calendar quarter in which the First Commercial Sale of a Unilateral Product
is made. Royalties shall be calculated in accordance with GAAP and with the
terms of this Article 3. Only one royalty payment will be due on Net Sales of a
given Unilateral Product even though the manufacture, sale or use of such
Unilateral Product may be covered by more than one intellectual property right
in a country.

        SECTION 3.5 ROYALTY STATEMENTS. Medarex shall deliver to Northwest
within forty-five (45) days after the end of each calendar quarter in which
Unilateral Products, for which Medarex owes a royalty hereunder, are sold, a
detailed statement showing (a) Net Sales of each such Unilateral Product, (b)
the number of units of each such Unilateral Product sold on a country-by-country
basis during the applicable calendar quarter, and (c) the amount and calculation
of royalties due on such Net Sales.

        SECTION 3.6 PAYMENT METHOD. All amounts due by Medarex hereunder shall
be paid in U.S. dollars by wire transfer in immediately available funds to an
account designated by Northwest. 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 (2) percentage points, or
the maximum rate permitted by law, calculated on the number of days such
payment is delinquent, compounded monthly.

        SECTION 3.7 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 royalty payments relate. If at any time legal
restrictions prevent the prompt remittance of any royalties with respect to Net
Sales in any jurisdiction, Medarex may notify Northwest 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 Northwest, and Medarex shall have no
further obligations under this Agreement with respect thereto.

        SECTION 3.8 TAXES. Medarex may deduct from any royalty amounts it is
required to pay pursuant to this Agreement any Withholding Taxes. At Northwest's
request, Medarex shall provide Northwest a certificate evidencing payment of any
Withholding Taxes hereunder and shall reasonably assist Northwest, at
Northwest's expense, to obtain the benefit of any applicable tax treaty.

        SECTION 3.9 RECORDS RETENTION; AUDIT.

            3.9.1 RECORD RETENTION. Medarex shall maintain (and shall ensure
that its Affiliates and sublicensees shall maintain) complete and accurate
books, records and accounts that fairly reflect their respective Net Sales of
Unilateral Products in sufficient detail to confirm the accuracy of any payments
required hereunder and in accordance

                                       8
<PAGE>   94

with GAAP, which books, records and accounts shall be retained by Medarex until
the later of (a) three (3) years after the end of the period to which such
books, records and accounts pertain, and (b) 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.

            3.9.2 AUDIT. Northwest shall have the right to have an independent
certified public accounting firm of nationally recognized standing, reasonably
acceptable to Medarex, to have access during normal business hours, and upon
reasonable prior written notice, to such of the records of Medarex (and its
Affiliates and sublicensees) as may be reasonably necessary to verify the
accuracy of such Net Sales for any calendar quarter ending not more than
thirty-six (36) months prior to the date of such request, provided, however,
that Northwest shall not 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 Net Sales are correct or incorrect and the specific details
concerning any discrepancies. No other information shall be provided to
Northwest. Northwest 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 Medarex shall bear the cost of the audit. The results of such accounting
firm shall be final, absent manifest error.

            3.9.3 PAYMENT OF ADDITIONAL ROYALTIES. If, based on the results of
such audit, additional payments are owed by Medarex under this Agreement,
Medarex shall make such additional payments, with interest from the date
originally due as provided in Section 3.6, within forty-five (45) days after the
date on which such accounting firm's written report is delivered to Medarex.

        SECTION 3.10 CONFIDENTIALITY. Northwest shall treat all information
subject to review under Section 3.9 in accordance with the confidentiality
provisions of Article 4 and shall cause its accounting firm to enter into a
reasonably acceptable confidentiality agreement with Medarex obligating such
firm to maintain all such financial information in confidence pursuant to such
confidentiality agreement.

                                   ARTICLE 4 -
                                 CONFIDENTIALITY

        SECTION 4.1 CONFIDENTIAL INFORMATION. The confidentiality and use
restrictions set forth in Sections 6.1 through 6.4 of the Collaboration
Agreement shall apply to all Confidential Information during the Term of this
Agreement and for a period of five (5) years thereafter, provided, however, that
Northwest recognizes that by reason of Medarex's status as an exclusive licensee
pursuant to the grant under Section 2.1, Medarex has an interest in Northwest's
retention in confidence of certain information of Northwest. Accordingly,
Northwest shall, and shall cause its officers, directors, employees and agents
to, keep completely confidential, and not publish or otherwise disclose, and not
use directly or indirectly for any purpose, any information relating solely to
the Unilateral Products, except to the extent (a) such information is in the
public domain through no fault of Northwest, its Affiliates or any of their
respective officers, directors, employees and agents, (b) such disclosure or use
would be permitted under Section 6.4 of the Collaboration Agreement, or (c) such
disclosure or use is otherwise

                                       9
<PAGE>   95

expressly permitted by the terms of this Agreement or is reasonably necessary
for the performance of this Agreement. For clarification, the disclosure by
Northwest to Medarex or by Medarex to Northwest of certain information of
Northwest relating solely to the Unilateral Products shall not cause such
information to cease to be subject to the confidentiality provisions of Sections
6.1 through 6.4 of the Collaboration Agreement.

        SECTION 4.2 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.

        SECTION 4.3 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 4.4 PUBLICATIONS. At least sixty (60) days prior to submission
for publication, presentation or other public disclosure by Medarex or any of
its Affiliates of any material pertaining to or resulting from the Northwest
Technology, Medarex shall provide to Northwest a draft of such material for its
review and comment. No publication or presentation with respect to the Northwest
Technology shall be made unless and until Northwest's comments on the proposed
publication or presentation have been addressed and changes have been agreed
upon and any information determined by Northwest to be Confidential Information
has been removed If requested in writing by Northwest, Medarex 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 5 -
                              INTELLECTUAL PROPERTY

        SECTION 5. 1 INTELLECTUAL PROPERTY OWNERSHIP.

            5.1.1 OWNERSHIP OF TECHNOLOGY. Subject to Section 5.1.2 and the
license grants to Medarex under Article 2, as between the Parties, each Party
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 such Party (or its Affiliates or its
licensees or sublicensees (other than the other Party 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

                                       10
<PAGE>   96

Information and Inventions, or any Patent or other intellectual property rights
with respect thereto, are Collaboration Technology or Joint 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 such Party, its Affiliates or its licensees or sublicensees
(other than such other Party), and (c) other Technology of such Party.

            5.1.2 OWNERSHIP OF MICE-RELATED TECHNOLOGY. 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)
there are no licenses granted to Northwest under this Agreement with respect to
the Mice Materials and Mice-Related Technology and 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, 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.

            5.1.3 OWNERSHIP OF JOINT TECHNOLOGY. Subject to Section 5.1.2 and
the license grants under Article 3, the Parties shall each own an equal,
undivided interest in any and all (a) Information and Inventions, conceived,
discovered, developed or otherwise made, as necessary to establish authorship,
inventorship or ownership under Applicable Law, jointly by or on behalf of
Medarex (or its Affiliates or, to the extent permitted, its sublicensees), on
the one hand, and Northwest (or its Affiliates or, to the extent permitted, its
sublicensees), on the other hand, in connection with the work conducted under or
in connection with this Agreement, whether or not patented or patentable, but
excluding any Mice Materials or Mice-Related Technology, and (b) patents
(including (x) all patents and patent applications, (y) any substitutions,
divisions, continuations, continuations-in-part, reissues, renewals,
registrations, confirmations, reexaminations, 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) (the, "JOINT PATENTS") and other
intellectual property rights with respect thereto (collectively, the "JOINT
TECHNOLOGY"), provided, however, that, except as otherwise expressly provided
herein, neither a Party nor any of its Affiliates, licensees or sublicensees
shall, directly or indirectly, Exploit any

                                       11
<PAGE>   97

Joint Technology or other such intellectual property rights without the consent
of the other Party, not to be unreasonably withheld or delayed. 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 Joint Technology.

            5.1.4 OWNERSHIP OF PRODUCT TRADEMARKS. Medarex shall own all right,
title and interest in and to each Product Trademark with respect to a Unilateral
Product. Northwest hereby assigns all of its right, title and interest in and to
any Product Trademark to Medarex to the extent that such Product Trademark
relates solely to the Unilateral Products.

            5.1.5 OWNERSHIP OF REGULATORY DOCUMENTATION. Medarex shall own all
right, title and interest in and to all Regulatory Documentation that relates
solely to the Unilateral Products. Northwest hereby assigns to Medarex such of
its right, title and interest in and to such Regulatory Documentation as is
necessary to vest ownership of such Regulatory Documentation in Medarex as
provided in the immediately preceding sentence. Notwithstanding the ownership of
any Regulatory Documentation, each Party shall have the right to use and
reference any of the Regulatory Documentation in connection with the
Exploitation of Unilateral Products as provided in this Agreement and
Collaboration Products as provided in the Collaboration Agreement.

            5.1.6 NOTICES. To the extent that Medarex has the right to (a)
assign, transfer, convey or otherwise encumber any right, title or interest in
or to any Northwest Technology, Joint Technology or Collaboration Technology,
(b) grant any license or other right, title or interest in or to any Northwest
Technology, Joint Technology or Collaboration Technology, or (c) agree to or
otherwise become bound by any covenant not to sue for any infringement, misuse
or other action or inaction with respect to any Northwest Technology, Joint
Technology or Collaboration Technology, in each case Medarex shall not do so,
directly or indirectly, expressly or by implication, by action or omission or
otherwise without providing Northwest with at least sixty (60) days advance
written notice thereof.

        SECTION 5.2 PROSECUTION OF PATENTS AND TRADEMARKS.

            5.2.1 NORTHWEST PATENTS. As between the Parties, Northwest shall,
subject to Section 5.2.5, have the sole right, at its cost and expense, to
obtain, prosecute and maintain throughout the world the Northwest Patents;
provided, however, that Medarex shall reimburse Northwest for one hundred
percent (100%) of the reasonable out-of-pocket costs incurred by Northwest for
filing, prosecuting and maintaining such Patents to the extent that they claim
or cover (x) as a composition of matter, a Unilateral Product or any active
ingredient in such Unilateral Product or (y) the use of any such Unilateral
Product or ingredient. Medarex shall, and shall cause its Affiliates, licensees
and sublicensees, as applicable, to, cooperate fully with Northwest in the
preparation, filing, prosecution, and maintenance of Northwest's Patents. 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 Northwest to

                                       12
<PAGE>   98

file, prosecute, and maintain its Patents in any country; and (b) promptly
informing Northwest of matters that may affect the preparation, filing,
prosecution, or maintenance of any such Patents.

            5.2.2 JOINT PATENTS. The Parties shall cooperate with one another
with respect to the filing, prosecution and maintenance of all Joint 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 associated with the filing, prosecution (including any
interferences, reissue proceedings and reexaminations) and maintenance of all
Joint Patents. If a Party elects not to pursue the filing, prosecution or
maintenance of a Joint Patent in a particular country, or to take any other
action with respect to Joint Technology 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 Joint
Technology 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 the right, but not
the obligation, to pursue the filing or registration, or support the continued
prosecution or maintenance, of such Patent 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 2, promptly release or assign
to such other Party, without compensation, all right, title and interest in and
to such Patent in such country.

            5.2.3 PATENT FILINGS. 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.

        SECTION 5.3 ENFORCEMENT OF PATENTS AND TRADEMARKS.

            5.3.1 RIGHTS AND PROCEDURES. If either Party determines that any
Technology (which for purposes of this Agreement shall be deemed to include
Joint Technology) of the other Party 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 such 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.

                                       13
<PAGE>   99

                (a) JOINT TECHNOLOGY. With respect to Joint Technology, the
Parties shall have the first right to jointly remove such infringement using
commercially appropriate steps, including the filing of an infringement suit or
taking other similar action. Each Party shall be responsible for half of the
reasonable and verifiable costs and expenses incurred in connection with such
action. In the event the Parties fail to jointly take commercially appropriate
steps to remove any infringement of any Joint Technology within ninety (90) days
following notice of such infringement, or a Party earlier notifies the other in
writing of its intent not to take such steps, the Party pursuing the filing,
prosecution or maintenance of a Patent comprising such Joint Technology (the
"PROSECUTING PARTY") shall have the right to do so at its own expense, or, in
the event such Party declines, the other Party shall have the right to do so at
its own expense; provided, however, that if the Parties have jointly commenced
negotiations with an alleged infringer for discontinuance of such infringement
within such ninety (90) day period, the Parties shall have an additional ninety
(90) days to conclude their negotiations before a Party unilaterally may bring
suit for such infringement.

                (b) NORTHWEST TECHNOLOGY. With respect to Northwest Technology,
Northwest shall have the first right, but not the obligation, to remove such
infringement at its sole cost and expense. In the event Northwest fails to take
commercially appropriate steps to remove any infringement of such Technology
within ninety (90) days following notice of such infringement, or earlier
notifies Medarex in writing of its intent not to take such steps, Medarex shall
have the right to do so at its sole cost and expense; provided, however, that
if Northwest has commenced negotiations with an alleged infringer for
discontinuance of such infringement within such ninety (90) day period,
Northwest shall have an additional ninety (90) days to conclude its negotiations
before Medarex may bring suit for such infringement; and provided further that
Medarex shall reimburse Northwest for one hundred percent (100%) of the
reasonable out-of-pocket costs incurred by Northwest with respect to the removal
of any such infringement with respect to any Unilateral Product.

            5.3.2 COOPERATION. The Party not enforcing the applicable Technology
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.

            5.3.3 RECOVERY. Any amounts recovered by a Party pursuant to Section
5.3.1, 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 Unilateral 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 Unilateral Product.

                                       14
<PAGE>   100

        SECTION 5.4 POTENTIAL THIRD PARTY RIGHTS.

            5.4.1 THIRD PARTY LICENSES. If (a) in the opinion of outside patent
counsel to Medarex, Medarex, or any of its Affiliates, licensees or permitted
sublicensees, cannot Exploit a Unilateral Product in a country in the Territory
without infringing one or more Patents that have issued to a Third Party in such
country, or (b) a result of any claim made against a Party, or any of its
Affiliates, licensees or permitted sublicensees, alleging that the Exploitation
of a Unilateral 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 Medarex cannot Exploit
such Unilateral Product in such country without infringing the Patent or other
proprietary rights of such Third Party, then, in either case, Medarex shall have
the first right, but not the obligation to negotiate and to obtain a license
from such Third Party as necessary for the Exploitation of any Unilateral
Products hereunder in such country. Medarex shall be solely responsible for one
hundred percent (100%) of all royalty and other obligations with respect to the
Exploitation of Unilateral Products.

            5.4.2 THIRD PARTY LITIGATION. 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
Unilateral 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. Medarex shall direct and control, at
its sole cost and expense, any Infringement Suit with respect to the Unilateral
Products; provided, however, that Medarex shall not cease to defend, settle or
otherwise dispose of a suit with respect to any intellectual property of
Northwest without Northwest's prior written consent. With respect to the Joint
Patents, the Parties shall each bear fifty percent (50%) of any costs and
expenses of such defense, and, with respect to the Exploitation of Unilateral
Products, Medarex shall bear one hundred percent (100%) of those costs and
expenses.

            5.4.3 RETAINED RIGHTS. Nothing in this Section 5.4 shall prevent
Medarex, 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 under this Agreement.

        SECTION 5.5 EXCHANGE OF KNOW-HOW.

            5.5.1 INFORMATION DISCLOSURE. Northwest shall, and shall cause its
Affiliates to, without additional compensation and at its sole expense, disclose
and make available to Medarex, in whatever form Medarex may reasonably request,
all Regulatory Documentation, all of its other Know-How, all Information and
Inventions included in the Collaboration Technology and the Joint Technology and
any other Information and

                                       15
<PAGE>   101

??ventions that are reasonably necessary to Exploit Antibody Products with
respect to ??ch Unilateral Target immediately after such Unilateral Target is
first designated as such ??d thereafter immediately upon the earlier of the
conception or reduction to practice, ??scovery, development or making of each
such Regulatory Documentation, Know-How, ?? other Information and Inventions.

            5.5.2  COOPERATION. Northwest shall cooperate with any and all
??asonable requests for assistance from Medarex, at Medarex's sole cost and
expense, ??cluding by making its employees, consultants and other scientific
staff available upon ??asonable notice during normal business hours at
Northwest's place of business to ??nsult with Medarex on issues arising with
respect to the Northwest Technology in ??nnection with the research,
development, commercialization or other Exploitation of ??nilateral Products.

            5.5.3  BIOLOGICAL MATERIALS. For purposes of facilitating the
conduct of ??e development activities with respect to the Unilateral Products,
Northwest shall ??ovide to Medarex the Biological Materials necessary to perform
such activities. The ??rties agree that: (a) all such Biological Materials
provided by Northwest to Medarex ??d any Biological Material produced against or
with, or derived from, such Biological ??aterials shall be used solely for the
development and commercialization of Unilateral ??oducts, and in material
compliance with all Applicable Law; (b) all such Biological ??aterials shall be
provided without any warranties, express or implied; (c) Northwest ??all obtain
(or cause its Third Party collaborators to obtain or certify that they have
??tained) all appropriate and required consents from the source of such
Biological ??aterials; and (d) Biological Materials provided by Northwest to
Medarex shall not be ?ade available by Medarex to any Third Party, unless the
prior written consent of ?orthwest is first obtained.

            5.5.4  REGULATORY RECORDS. Medarex shall maintain, or cause to be
?aintained, records of its respective research, development, manufacturing and
??mmercialization activities for the Unilateral Products, including all
Regulatory ?ocumentation, in sufficient detail and in good scientific manner
appropriate for patent ??d regulatory purposes, which shall be complete and
accurate and shall fully and ??operly reflect all work done and results
achieved in the performance of such activities, ??d which shall be retained
during the term of this Agreement and for a period of five (5) ??ars
thereafter, or for such longer period as may be required by Applicable Law.
?orthwest shall have the right, during normal business hours and upon
reasonable notice, inspect and copy any such records, except to the extent that
such records contain ??oprietary information with respect to the HuMAb Mice or
the Production Process ??chnology. Northwest shall have an irrevocable,
perpetual right to use and reference ??ch Regulatory Documentation for all
purposes.

                                  ARTICLE 6 -
                              TERM AND TERMINATION

      SECTION 6.1  TERM. The term of this Agreement (the "TERM") shall commence
??on the Effective Date and shall continue in effect until such time as there
is no longer

                                       16
<PAGE>   102

any Unilateral Product being Exploited hereunder, unless terminated at an
earlier date in accordance with the terms and conditions set forth in this
Article 6.

        SECTION 6.2 TERMINATION OF AGREEMENT FOR MATERIAL BREACH. 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
notice specifying the nature of the default, requiring the defaulting Party to
make good or otherwise cure such default, and stating its intention to terminate
if such default is not cured. If such default is not cured within thirty (30)
days after the receipt of such notice (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 ninety
(90) days after the receipt of such notice), the Parties not in default shall be
entitled, 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 terminate this Agreement in its entirety.

        SECTION 6.3 TERMINATION OF RIGHTS WITH RESPECT TO UNILATERAL PRODUCTS
UPON MATERIAL BREACH. Any material failure by Medarex to comply with any of its
material obligations contained herein with respect to a Unilateral Product shall
entitle Northwest to give to Medarex notice specifying the nature of the
default, requiring Medarex to make good or otherwise cure such default, and
stating its intention to convert such Unilateral Product to a Unilateral Product
of Northwest under the Unilateral Development and Commercialization Agreement
attached to the Collaboration Agreement as Appendix D-1 if such default is not
cured. If such default is not cured within thirty (30) days after the receipt of
such notice (or, if such default cannot be cured within such thirty (30)-day
period, if Medarex 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 ninety (90) days after the receipt of such notice),
Northwest shall be entitled, on written notice to Medarex, to convert such
Unilateral Product to a Unilateral Product of Northwest, whereupon each shall be
subject to their respective rights and obligations under the Unilateral
Development and Commercialization Agreement attached to the Collaboration
Agreement as Appendix D-1, including the royalty obligations set forth therein
(provided that the royalty rate owed by Northwest pursuant to such Unilateral
Development and Commercialization Agreement shall equal the royalty rate that
Medarex would have owed Northwest had it not defaulted) and the indemnification
obligations.

        SECTION 6.4 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.

                                       17
<PAGE>   103
        SECTION 6.5 RIGHTS IN BANKRUPTCY. All rights and licenses granted under
or pursuant to this Agreement by Northwest or Medarex 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.

        SECTION 6.6 CONSEQUENCES OF EXPIRATION OR TERMINATION.

            6.6.1 LICENSES. Upon expiration of the full term of this Agreement
in accordance with Section 6.1 and the payment of all amounts due under Section
3.1, the licenses granted by Northwest to Medarex hereunder shall be deemed
fully-paid up.

            6.6.2 RETURN OF INFORMATION. Upon expiration of this Agreement
pursuant to Section 6.1 or upon termination of this Agreement in its entirety by
either Party pursuant to this Article 6, Medarex, at the request of Northwest,
shall return all data, files, records and other materials in its possession or
control relating to Northwest's Technology, or containing or comprising
Northwest's Information and Inventions or other Confidential Information and to
which Medarex does not retain rights hereunder (except one copy of which may be
retained for archival purposes).

        SECTION 6.7 ACCRUED RIGHTS; SURVIVING OBLIGATIONS.

            6.7.1 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.

            6.7.2 SURVIVAL. Articles 3 (with respect to obligations arising
prior to expiration or termination), 4 and 7, and Sections 2.3, 5.1, 5.2, 5.5.3,
5.5.4, 6.5, 6.6, 9.4, 9.5 and 9.6 of this Agreement and this Section 6.7 shall
survive expiration or termination of this Agreement for any reason.

                                       18
<PAGE>   104

                                   ARTICLE 7 -
                          INDEMNIFICATION AND INSURANCE

        SECTION 7.1 INDEMNIFICATION OF MEDAREX. Northwest shall indemnify
Medarex, 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 any breach by Northwest of this
Agreement, except for those Losses for which Medarex has an obligation to
indemnify Northwest and its Affiliates pursuant to Section 7.2, as to which
Losses each Party shall indemnify the other to the extent of their respective
liability for the Losses.

        SECTION 7.2 INDEMNIFICATION OF NORTHWEST. Medarex shall indemnify
Northwest and its Affiliates, 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, (b) the development, manufacture or commercialization
of a Unilateral Product by or on behalf of Medarex or its Affiliates or
sublicensees, or (c) 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 pursuant to Section 7.1, as to which Losses
each Party shall indemnify the other to the extent of their respective liability
for the Losses.

        SECTION 7.3 INDEMNIFICATION PROCEDURE.

            7.3.1 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 7.1 or Section 7.2, 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").

            7.3.2 THIRD PARTY CLAIMS. Subject to Section 5.4, the obligations of
an indemnifying Party under this Article 7 with respect to Losses arising from
claims of any Third Party that are subject to indemnification as provided for in
Section 7.1 or 7.2 (a "THIRD PARTY CLAIM") shall be governed by and be
contingent upon the following additional terms and conditions:

                                       19
<PAGE>   105

                (a) CONTROL OF DEFENSE. 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. 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 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. 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
7.3.2(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
7.3.2(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 7.3.2(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

                                       20
<PAGE>   106

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 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 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 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 7.4 INSURANCE. Medarex 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 8 -
                         REPRESENTATIONS AND WARRANTIES

        SECTION 8.1 REPRESENTATIONS, WARRANTIES AND COVENANTS. Each Party is
entering into this Agreement in reliance upon the representations, warranties
and covenants of the other Party set forth in Sections 10.1, 10.2 and 10.3 of
the Collaboration Agreement.

        SECTION 8.2 DISCLAIMER OF WARRANTY. EXCEPT FOR THE EXPRESS WARRANTIES
SET FORTH IN SECTIONS 10.1, 10.2 AND 10.3 OF THE COLLABORATION AGREEMENT,
MEDAREX AND NORTHWEST MAKE NO REPRESENTATIONS AND GRANT NO WARRANTIES, EXPRESS
OR IMPLIED, EITHER IN FACT OR BY OPERATION OF LAW, BY STATUTE OR OTHERWISE, AND
MEDAREX AND NORTHWEST EACH SPECIFICALLY DISCLAIM ANY OTHER WARRANTIES, WHETHER
WRITTEN OR ORAL, OR EXPRESS OR

                                       21
<PAGE>   107

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 9 -
                                  MISCELLANEOUS

        SECTION 9.1 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 Patty 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.

        SECTION 9.2 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 Medarex Affiliate, Northwest Affiliate or
Third Party assignee under this Agreement, and (ii) the relevant Medarex
Affiliate assignee, Northwest 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 9.3 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

                                       22
<PAGE>   108

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 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 9.4 DISPUTES. Any dispute that may arise relating to this
Agreement 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. 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, then either Party shall have the right to litigate such dispute in
accordance with Section 9.5 or to pursue such other dispute resolution mechanism
as the Parties may agree.

        SECTION 9.5 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. 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 9.6 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:

                                       23
<PAGE>   109

        If to Northwest, to:

                         Northwest Biotherapeutics, Inc.
                         21270 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

        If to Medarex, to:

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

                         with copies 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 9.6 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 9.7 ENTIRE AGREEMENT; MODIFICATIONS. This Agreement, together
with the Collaboration Agreement, sets forth and constitutes the entire
agreement and

                                       24
<PAGE>   110

understanding between the Parties with respect to the subject matter hereof and
thereof and all prior agreements, understanding, promises and representations,
whether written or oral, with respect thereto are superseded hereby and thereby.
Each Party confirms that it is not relying on any representations or warranties
of the other Party except as specifically set forth herein or therein. 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 9.8 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 9.9 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 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 9.10 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 9.11 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 9.12 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 9.13 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.

                                       25
<PAGE>   111

        SECTION 9.14 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 9.15 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.

             [The remainder of this page intentionally left blank.]

                                       26
<PAGE>   112

            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: /s/ DONALD L. DRAKEMAN              By: /s/ DANIEL O. WILDS
   -----------------------------           -------------------------------

Name: Donald L. Drakeman                Name: Daniel O. Wilds
     ---------------------------             -----------------------------

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

Signature Page of Appendix D-2 Unilateral Development and Commercialization
Agreement

                                       27
<PAGE>   113

                                   APPENDIX A
               COLLABORATION ANTIBODIES AND COLLABORATION PRODUCTS

        This Appendix to the UNILATERAL DEVELOPMENT AND COMMERCIALIZATION
AGREEMENT ("AGREEMENT") effective as of April 24, 2001, by and between NORTHWEST
BIOTHERAPEUTICS, INC. ("NORTHWEST") and MEDAREX, INC., on behalf of itself and
its wholly owned subsidiary, GENPHARM INTERNATIONAL, INC., (collectively,
"MEDAREX") sets forth the Collaboration Antibodies with respect to the
applicable Collaboration Targets.

        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.

                                       1
<PAGE>   114

                                   APPENDIX E

                                  SCHEDULE 10.2

                         MEDAREX SCHEDULE OF EXCEPTIONS

Complaint filed on May 24, 2000 by Lexicon Genetics Incorporated ("Lexicon")
against Deltagen, Inc. ("Deltagen") in U.S. District Court for the District of
Delaware regarding alleged infringement of United States Patent No.5,789,215,
under which Lexicon holds an exclusive license from Medarex's wholly-owned
subsidiary, GenPharm International, Inc ("GenPharm"). On October 31, 2000,
Lexicon amended its complaint to add GenPharm as a plaintiff. On November 14,
2000, Deltagen filed an answer to Lexicon's amended complaint which included
counterclaims against Lexicon and GenPharm, seeking declaratory relief that the
patent is invalid, unenforceable and not infringed.

                                  SCHEDULE 10.3

                        NORTHWEST SCHEDULE OF EXCEPTIONS

                                      None

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