<PAGE>
                                                                    Exhibit 10.1

*Certain confidential information contained in this document, marked by
brackets, has been omitted and filed with the Securities and Exchange Commission
pursuant to Rule 24b-2 of the Securities Exchange Act of 1934, as amended.



                            ASSET PURCHASE AGREEMENT

                                      AMONG

                               CORIXA CORPORATION,

                          COULTER PHARMACEUTICAL, INC.,

                              CORIXA BELGIUM, S.A.,

                                  MEDAREX, INC.

                                       AND

                              MEDAREX BELGIUM, S.A.
          (AN ENTITY IN THE PROCESS OF BEING FORMED UNDER BELGIAN LAW)




                                  MAY 23, 2002


<PAGE>


                                TABLE OF CONTENTS

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

2.      SALE AND PURCHASE..................................................................10

        2.1    Transfer of Assets..........................................................10

        2.2    Transfer of Liabilities.....................................................10

        2.3    Excluded Liabilities........................................................10

        2.4    Purchase Price..............................................................10

        2.5    Allocation of Purchase Price................................................14

3.      CLOSING AND FUTURE PAYMENTS........................................................14

        3.1    Closing.....................................................................14

        3.2    Actions at the Closing......................................................14

4.      REPRESENTATIONS AND WARRANTIES OF SELLERS..........................................15

        4.1    Organization and Good Standing..............................................15

        4.2    Authority; Authorization; Enforceability....................................15

        4.3    No Default or Violation.....................................................16

        4.4    Title to Assets.............................................................16

        4.5    Licenses and Permits; Compliance With Law...................................16

        4.6    Assigned Contracts..........................................................17

        4.7    Intellectual Property.......................................................18

        4.8    Litigation; Other Claims....................................................19

        4.9    Brokers and Finders.........................................................19

        4.10   Fair Consideration; No Fraudulent Conveyance................................19

        4.11   Employee and Labor Matters..................................................20

        4.12   Equipment...................................................................20

5.      REPRESENTATIONS AND WARRANTIES OF THE BUYERS.......................................21

        5.1    Organization and Good Standing..............................................21

        5.2    Authority; Authorization; Enforceability....................................21

        5.3    No Default or Violation.....................................................21

        5.4    Valid Issuance; Freely Tradeable Shares.....................................21

        5.5    Capitalization; Nasdaq Listing..............................................22

        5.6    Registration Statement; Medarex SEC Reports.................................22
</TABLE>


                                      -i-
<PAGE>


                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                                          PAGE
                                                                                          ----
<S>     <C>                                                                               <C>
        5.7    Absence of Certain Changes..................................................23

        5.8    Brokers and Finders.........................................................23

        5.9    Prospectus Delivery.........................................................23

6.      COVENANTS..........................................................................23

        6.1    Access to Information.......................................................23

        6.2    Further Action; Commercially Reasonable Efforts.............................23

        6.3    Related Data and Records....................................................24

        6.4    Confidentiality.............................................................25

        6.5    Public Disclosure...........................................................25

        6.6    Taxes.......................................................................25

        6.7    Securities Law Matters......................................................25

        6.8    Formation of Medarex Belgium................................................26

        6.9    Removal of Liens............................................................26

        6.10   Termination of Assigned Contracts...........................................26

7.      SCHEDULED EMPLOYEES................................................................26

        7.1    Transition of Scheduled Employees...........................................26

        7.2    Compensation of New Medarex Employees.......................................27

        7.3    Compensation and Benefits of Scheduled Employees............................27

        7.4    No Right to Continued Employment or Benefits................................28

        7.5    Certain Payments............................................................28

        7.6    Waiver of Tail Provision....................................................28

        7.7    Ownership of Scheduled Employee Inventions..................................28

        7.8    Ownership of Intellectual Property Developed by Scheduled Employees Who
               Do Not Join Medarex.........................................................29

        7.9    New Medarex Employee Records................................................29

8.      DELIVERIES.........................................................................30

        8.1    Deliveries by Sellers.......................................................30

        8.2    Deliveries by the Buyers....................................................31

9.      INDEMNIFICATION....................................................................31

        9.1    Survival....................................................................31
</TABLE>


                                      -ii-
<PAGE>


                                TABLE OF CONTENTS
                                   (continued)

<TABLE>
<CAPTION>
                                                                                          PAGE
                                                                                          ----
<S>     <C>                                                                               <C>
        9.2    Indemnification by Sellers..................................................32

        9.3    Indemnification by the Buyers...............................................33

        9.4    Indemnification Procedures..................................................33

        9.5    Limitations on Indemnification..............................................35

10.     MISCELLANEOUS......................................................................36

        10.1   Expenses....................................................................36

        10.2   Amendments and Waivers......................................................36

        10.3   Successors and Assigns......................................................36

        10.4   Governing Law...............................................................36

        10.5   Counterparts................................................................36

        10.6   Titles and Subtitles........................................................37

        10.7   Notice......................................................................37

        10.8   Severability................................................................38

        10.9   Cumulative Remedies.........................................................38

        10.10  Force Majeure...............................................................38

        10.11  Construction of Agreement...................................................38

        10.12  No Implied Waiver...........................................................38

        10.13  Entire Agreement............................................................38

        10.14  Waiver of Jury Trial........................................................38
</TABLE>

<TABLE>
<S>            <C>    <C>
Exhibit A      --     Form of Bill of Sale
Exhibit B1     --     Form of Assignment and Assumption Agreement
Exhibit B2     --     Form of Belgian Assignment and Assumption Agreement
Exhibit C      --     Form of Assignment of Patents
Exhibit D      --     Form of Opinion of Counsel for the Sellers, Orrick, Herrington &
                      Sutcliffe LLP
Exhibit E      --     Form of UPT License Agreement
Exhibit F      --     Form of [*] Agreement
Exhibit G      --     Form of Sublease
Exhibit H      --     Form of Opinion of Counsel for the Buyers, Cooley Godward LLP
Exhibit I      --     Form of Opinion of Counsel for the Buyers, Satterlee Stephens Burke &
                      Burke LLP
</TABLE>

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* Confidential Treatment Requested


                                     -iii-
<PAGE>


<TABLE>
<CAPTION>
                                                                                          PAGE
                                                                                          ----
<S>            <C>    <C>
Exhibit J      --     Form of Facilities Services and Lease Agreement
Exhibit K      --     Certain License Terms
Exhibit L      --     Form of Leader Peptide Patent License Agreement
</TABLE>


                                      -ii-
<PAGE>


                            ASSET PURCHASE AGREEMENT

        This Asset Purchase Agreement (this "Agreement") is entered into as of
May 23, 2002, by and among Medarex, Inc., a New Jersey corporation ("Medarex"),
Medarex Belgium, S.A., an entity in the process of being incorporated in Belgium
and a subsidiary of Medarex ("Medarex Belgium" and, together with Medarex, the
"Buyers"), Corixa Corporation, a Delaware corporation ("Corixa"), Coulter
Pharmaceutical, Inc., a Delaware corporation and wholly owned subsidiary of
Corixa ("Coulter") and Corixa Belgium, S.A., a Belgian corporation and
subsidiary of Corixa ("Corixa Belgium" and, together with Corixa and Coulter,
the "Sellers"). The Sellers, on the one hand, and the Buyers, on the other hand,
are each referred to herein as a "Party" and, collectively, as the "Parties."

                                    RECITALS

        WHEREAS, the Buyers and the Sellers are each engaged in a business that
includes the research and development of therapies for treating of autoimmune
diseases, cancer and infectious diseases; and

        WHEREAS, the Buyers wish to purchase from the Sellers, and the Sellers
wish to sell to the Buyers, all of the Sellers' right, title and interest in and
to certain product candidates and certain related technologies under development
by the Sellers, together with certain assets related thereto, all on the terms
and subject to the conditions set forth in this Agreement.

                                    AGREEMENT

        NOW, THEREFORE, in consideration of the mutual covenants contained
herein, and for other good and valuable consideration, the receipt and
sufficiency of which are hereby acknowledged, the Parties hereby agree as
follows:

1.      DEFINITIONS.

        In this Agreement, unless the context otherwise requires, the following
terms will have the following meanings:

        1.1 "ACTUAL SALES PROCEEDS" means the actual aggregate gross proceeds
(before deducting sales commissions or brokers fees) Corixa receives from sales
of the Medarex Stock that constitutes the applicable Monthly Issuance during the
one-month period following the date of issuance of such Monthly Issuance.

        1.2 "AFFILIATE" means with respect to a particular Party, any Person
that, whether in fact or Law, directly or indirectly owns, is owned by or is
under common ownership with such Party to the extent of more than fifty percent
(50%) of the voting equity (or such lesser percentage which is the maximum
allowed to be owned by a foreign corporation in a particular jurisdiction)
having the power to direct the affairs of the Person, or any Person actually
controlled by, controlling or under common control with a Party. As used in this
Section 1.2, a Person controls another Person (or is controlled by or under
common control with another


<PAGE>


Person) if a Person has the actual ability to control and direct the management
of the other Person, whether by contract or otherwise. Notwithstanding the
foregoing, no affiliate created, incorporated, formed or acquired, by operation
of law or otherwise, by or on behalf of a Party following the Effective Date
shall be considered an Affiliate hereunder until such Party provides written
notice to the other Party of the existence and identity of such Affiliate. As
used in this Agreement, any grant of rights to an Affiliate of one Party shall
remain in effect only for so long as they remain an Affiliate of such Party.

        1.3 "ASSETS" means the Transferred Intellectual Property Rights,
Assigned Contracts, Materials, Equipment and Data and Records.

        1.4 "ASSET MATERIAL ADVERSE EFFECT" means any event, change or effect
that materially diminishes the value of the Assets, taken as a whole.

        1.5 "ASSIGNED CONTRACTS" means the contracts (or surviving rights and
provisions of terminated contracts, as applicable) listed on Schedule 2.1 to the
Seller Disclosure Memorandum or assigned to the Buyers after the Closing
pursuant to Section 6.2(c).

        1.6 "ASSIGNMENT AND ASSUMPTION AGREEMENT" has the meaning given such
term in Section 3.2(a).

        1.7 "ASSIGNMENT OF PATENTS" has the meaning given such term in Section
3.2(a).

        1.8 "ASSUMED LIABILITIES" has the meaning given such term in Section
2.2.

        1.9 "BASE PRICE" means the average of the closing trading prices of
Medarex's common stock for each of the trading days during the five-trading-day
period ending two trading days immediately prior to the applicable date of
issuance of Medarex Stock, as publicly reported on Nasdaq.

        1.10 "BELGIAN ASSETS" means those Assets to be transferred to Medarex
Belgium, as set forth on Schedule 2.1 to the Seller Disclosure Memorandum.

        1.11 "BELGIAN ASSIGNMENT AND ASSUMPTION AGREEMENT" has the meaning given
such term in Section 3.2(a).

        1.12 "BILL OF SALE" has the meaning given such term in Section 3.2(a).

        1.13 "BUYER MATERIAL ADVERSE EFFECT" means any event, change or effect
that is materially adverse to the condition (financial or otherwise),
properties, assets, liabilities, business, operations or results of operations
of the Buyers and their Affiliates, taken as a whole.

        1.14 "CLOSING" has the meaning given such term in Section 3.1.

        1.15 "CLOSING DATE" has the meaning given such term in Section 3.1.

        1.16 "CONCURRENTLY-KNOWN INFORMATION" means, collectively, any
information, including without limitation, Inventions, known, at or before the
Closing Date, to both (a) an


                                      -2-
<PAGE>


individual who is an employee of Corixa after the Closing Date and (b) a New
Medarex Employee, but which is not embodied in any descriptive writing, whether
in hard copy or electronic form, prior to the Closing Date; provided that
Concurrently-Known Information shall not include any information, including
without limitation, Inventions, that are included in or covered by the
Transferred Intellectual Property Rights.

        1.17 "CONFIDENTIALITY AGREEMENT" has the meaning given such term in
Section 6.4.

        1.18 "COPYRIGHTS" means all copyrights, and all other literary property
and authorship rights, and all right, title and interest in all copyrights,
copyright registrations, certificates of copyright and copyrighted interests
throughout the world.

        1.19 "DATA" means the data related to the Programs, as described on
Schedule 2.1 to the Seller Disclosure Memorandum or transferred to the Buyers
after the Closing pursuant to Section 6.2(c).

        1.20 "EMPLOYEE BENEFIT PLAN" means any plan, program, policy, practice,
contract, agreement or other arrangement providing for compensation, severance,
termination pay, deferred compensation, retirement benefits, performance awards,
stock or stock related awards, fringe benefits or other employee benefits or
remuneration of any kind, whether written or unwritten or otherwise, funded or
unfunded, including each "employee benefit plan," within the meaning of Section
3(3) of ERISA (whether or not ERISA is applicable thereto), which is or has been
maintained, contributed to, or required to be contributed to, by any Party or
such Party's Affiliates for the benefit of the Scheduled Employees.

        1.21 "EQUIPMENT" means the equipment identified on Schedule 2.1 to the
Seller Disclosure Memorandum.

        1.22 "ERISA" means the Employee Retirement Income Security Act of 1934,
as amended.

        1.23 "EXCHANGE ACT" means the Securities Exchange Act of 1934, as
amended.

        1.24 "EXCLUDED ASSETS" means all property and assets of the Sellers not
listed on Schedule 2.1 to the Seller Disclosure Memorandum or transferred to the
Buyers after the Closing pursuant to Section 6.2(c), all of which are expressly
excluded from the transfer pursuant to this Agreement.

        1.25 "FACILITIES SERVICES AND LEASE AGREEMENT" means the facilities
services and lease agreement between Coulter and Medarex in the form attached
hereto as Exhibit J.

        1.26 "GAAP" means United States generally accepted accounting
principles.

        1.27 "GOVERNMENTAL AUTHORIZATIONS" means all franchises, grants,
authorizations, licenses, permits, easements, variances, exceptions, consents,
certificates, approvals and Orders of, or filings with, any Governmental Entity.


                                      -3-
<PAGE>


        1.28 "GOVERNMENTAL ENTITY" means any federal, state, municipal or other
governmental authority, department, commission, board, agency, court or other
instrumentality (domestic or foreign), including the United States Food and Drug
Administration.

        1.29 "HEDGING TRANSACTION" means any transaction in which Corixa sells
Medarex Stock that it does not own or, if it does own such Medarex Stock, does
not deliver such stock against such sale within three (3) business days after
the sale (other than by reason of error, inadvertence, force majeure or other
circumstances beyond Corixa's control). Such transactions include, but are not
limited to, "short sales," "short sales against the box" and "forward sale
contracts."

        1.30 "INTELLECTUAL PROPERTY RIGHTS" means, collectively, Patents, Trade
Secrets, Copyrights, Trademarks, Know-how, moral rights, trade names, rights in
trade dress, and all other intellectual property rights and proprietary rights,
whether arising under the laws of the United States or any other state, country
or jurisdiction, including all rights or causes of action for infringement or
misappropriation of any of the foregoing.

        1.31 "INVENTIONS" means discoveries, developments, designs,
improvements, inventions and/or works of authorship, whether or not patentable,
copyrightable or otherwise legally protectable. This includes, but is not
limited to, any new machine, article of manufacture, biological material,
method, process, technique, use, equipment, device, apparatus, system, compound,
formulation, composition of matter, design or configuration of any kind, or any
improvement thereon.

        1.32 "KNOW-HOW" means all information not in the public domain,
including ideas, discoveries, inventions, data, formulae, techniques, procedures
for experiments and tests, technical information, specifications, results of
experiments and tests, designs, sketches, records and confidential analyses and
interpretations of information.

        1.33 "[*]" means [*]

        1.34 "[*] AGREEMENT" means that certain License Agreement dated [*]
between Coulter and [*].

        1.35 "LAW" means any federal, state, local, municipal or foreign
statute, law, regulation, legislation, constitution, requirement,
interpretation, permit, license, approval, authorization, rule, ordinance, code,
treaty, policy or rule of common law of any Governmental Entity, including any
judicial or administrative interpretation thereof.

        1.36 "LEADER PEPTIDE PATENT LICENSE AGREEMENT" has the meaning given
such term in Section 8.1(k).

        1.37 "LIABILITIES" means any and all debts, duties, liabilities and
obligations of any nature whatsoever, whether accrued or fixed, absolute or
contingent, mature or unmatured or determined or determinable, including those
arising under any Law, those arising under any contract, agreement, commitment,
instrument, permit, license, franchise or undertaking and those

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                                      -4-
<PAGE>


arising as a result of any act or omission, regardless of whether such debt,
duty, liability or obligation would be required to be disclosed on a balance
sheet prepared in accordance with GAAP and regardless of whether such debt,
duty, liability or obligation is immediately due and payable.

        1.38 "LICENSE" means a license granted to Corixa from Medarex pursuant
to Section 2.3 of the UPT License Agreement in connection with the exercise of a
License Option or Substitute Option.

        1.39 "LICENSE OPTION" means an option granted pursuant to Section 2.1 of
the UPT License Agreement to Corixa and its Affiliates from Medarex to obtain a
license under Section 2.3 of the UPT License Agreement.

        1.40 "LICENSE REVOCATION VALUE" means the dollar amount determined by
multiplying (y) the total number of License Options revoked pursuant to Section
2.4, by (z) One Million Dollars ($1,000,000).

        1.41 "LICENSED INTELLECTUAL PROPERTY" means all Intellectual Property
Rights licensed to any of the Sellers under the Assigned Contracts.

        1.42 "LIEN" means any mortgage, pledge, lien, security interest, option,
covenant, condition, restriction, encumbrance, charge, equitable interest,
preference, right of possession, lease, tenancy, license, encroachment,
infringement, interference, right of first refusal, preemptive right or other
third-party claim of any kind (including any restriction on transfer, receipt of
income, use, possession or other attribute of ownership).

        1.43 "LINKER TECHNOLOGY" means those Intellectual Property Rights
included within the Transferred Intellectual Property Rights or licensed to the
Sellers under the Third-Party Agreements relating to the methods and processes
(and related technology) for conjugating UPTs to monoclonal antibodies or to
fragments or derivatives of monoclonal antibodies.

        1.44 "MATERIALLY DISCOUNTED" with respect to a license to [*] technology
means that each of (i) [*] and (ii) [*] are discounted by at least [*]% from
[*], as set forth on Exhibit K.

        1.45 "MATERIALS" means all on-hand materials listed on Schedule 2.1 to
the Seller Disclosure Memorandum or transferred to the Buyers after the Closing
pursuant to Section 6.2(c).

        1.46 "MATERIALS OF ENVIRONMENTAL CONCERN" means: (a) any petroleum,
waste oil, crude oil, asbestos, urea formaldehyde or polychlorinated biphenyl;
(b) any waste, gas or other substance or material that is explosive or
radioactive; (c) any "hazardous substance," "pollutant," "contaminant,"
"hazardous waste," "regulated substance," "hazardous chemical" or "toxic
chemical" as designated, listed or defined (whether expressly or by reference)
in any statute, regulation or other Law (including CERCLA and any other so
called "superfund" or "superlien" law and the respective regulations promulgated
thereunder); (d) any other substance or material (regardless of physical form)
or form of energy that is subject to any Law which regulates or

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                                      -5-
<PAGE>


establishes standards of conduct in connection with, or which otherwise relates
to, the protection of human health, plant life, animal life, natural resources,
property or the enjoyment of life or property from the presence in the
environment of any solid, liquid, gas, odor, noise or form of energy; and (e)
any compound, mixture, solution, product or other substance or material that
contains any substance or material referred to in clause "(a)", "(b)", "(c)" or
"(d)" above.

        1.47 "MEDAREX SEC REPORTS" has the meaning given such term in Section
5.6.

        1.48 "MEDAREX STOCK" means (a) the common stock, par value $0.01 per
share, of Medarex, (b) such other securities into which the shares of common
stock of Medarex shall be converted by virtue of any recapitalization of
Medarex, any merger of Medarex with or into another entity or otherwise or (c)
the voting securities of any successor Person to Medarex by virtue of any sale
of all or substantially all of the assets of Medarex; provided in the case of
(b) and (c) above, that such class of securities are fully registered and freely
tradeable, without restriction under the Securities Act or otherwise, on a
United States national securities exchange or Nasdaq.

        1.49 "MONTHLY ISSUANCE" has the meaning given such term in Section
2.4(a).

        1.50 "NASDAQ" means the Nasdaq National Market System or such principal
United States national securities exchange on which the shares of Medarex Stock
are then traded.

        1.51 "[*] AGREEMENT" has the meaning given such term in Section 8.1(k).

        1.52 "OFFSET CONSIDERATION" has the meaning given such term in Section
2.4(b)(v).

        1.53 "OFFSET ELECTION" has the meaning given such term in Section
2.4(b)(v).

        1.54 "OPERATIVE DOCUMENTS" means (a) the Bill of Sale, (b) the
Assignment and Assumption Agreement, (c) the Belgian Assignment and Assumption
Agreement, (d) the Assignment of Patent, (e) the UPT License Agreement, (f) the
Leader Peptide Patent License Agreement, (g) the Sublease, (h) the Facilities
Services and Lease Agreement and (i) the [*] Agreement.

        1.55 "ORDER" means any (a) writ, judgment, injunction, consent, order,
decree, stipulation, award, edict, ruling, pronouncement, determination,
decision, verdict, sentence, subpoena, writ or executive order of or by any
Governmental Entity, arbitrator or arbitration panel or (b) contract with any
Governmental Entity entered into in connection with any Proceeding.

        1.56 "PATENTS" means all patent rights and all right, title and interest
in all letters patent or equivalent rights and applications, including
provisional applications, for letters patent or rights, industrial and utility
models, industrial designs, certificates of invention, and other government
issued or granted indicia of invention ownership, including any reissue,
extension, division, continuation or continuation-in-part applications
throughout the world.

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<PAGE>


        1.57 "PAYMENT DATE" means, with respect to the Monthly Issuance to be
made as of the Closing Date (if Medarex elects to pay such Monthly Issuance in
shares of Medarex Stock), the date on which the certificate representing such
shares of Medarex Stock is delivered to Corixa, which shall be as soon as
practicable and no later than three (3) business days after the Closing Date
and, with respect to any other Monthly Issuance, the same numerical calendar day
of the applicable month in which a Monthly Issuance is made as the numerical
calendar day of the Closing Date (or such later date as Medarex actually
delivers the certificate representing the Monthly Issuance to Corixa); provided,
however, that if with respect to any Monthly Issuance, such date does not fall
on a day on which Nasdaq is open for trading, the Issuance Date with respect to
such Monthly Issuance shall be the next succeeding Nasdaq trading day.

        1.58 "PERSON" means an individual, corporation (including any non-profit
corporation), general partnership, limited partnership, limited liability
partnership, joint venture, association, estate, trust, cooperative, foundation,
society, government or political subdivision or agency or instrumentality
thereof, union, limited liability company, joint stock company, firm or other
entity or organization.

        1.59 "PROCEEDING" means any action, suit, litigation, arbitration,
proceeding (including any civil, criminal, administrative, investigative or
appellate proceeding and any informal proceeding), prosecution, contest,
hearing, inquiry, inquest, audit, examination or investigation commenced,
brought, conducted or heard by or before or otherwise involving, any
Governmental Entity or any arbitrator or arbitration panel.

        1.60 "PRODUCT CANDIDATES" means product candidates under development by
the Sellers in the following projects: the Tumor Activated Pro-drug Program,
including the CPI-0004 Project; the Ultra Potent Toxins Program, including
Duocarmycin and its analogs for conjugation with any ligand including
antibodies; the [*] Program; the IFNAR1 Program; the [*] antibody Program; and
the [*] antibody Program, all as more particularly described in Schedule 2.1 to
the Seller Disclosure Memorandum.

        1.61 "PROGRAM MATERIAL ADVERSE EFFECT" means any event, change or effect
that is materially adverse to the operation of the Programs, taken as a whole,
as operated by Seller prior to the date of this Agreement.

        1.62 "PROGRAMS" means the business and operations (including all
research, development and commercialization activities) carried out with respect
to the Product Candidates or any component thereof, including, without
limitation, research and development, regulatory approval process and permits,
manufacturing, marketing and distribution to the extent that they related to
such Product Candidates and the conduct of clinical trials with respect thereto.

        1.63 "PROPRIETARY RIGHTS AND INVENTIONS AGREEMENT" means any agreement,
including the form of proprietary rights and inventions agreement delivered to
Medarex, between any Seller and any employee or consultant of any Seller,
pursuant to which such employee or consultant agreed to assign to a Seller
Intellectual Property Rights arising from his or her employment or consulting
relationship.

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                                      -7-
<PAGE>


        1.64 "PROSPECTUS SUPPLEMENT" means a prospectus supplement with respect
to the issuance of Medarex Stock (as defined in Section 2.4(b)) pursuant to this
Agreement that is required to be filed by Medarex with the SEC under Rule 424(b)
of the regulations of the Securities Act.

        1.65 "RECORDS" means the records, documents and files identified on
Schedule 2.1 to the Seller Disclosure Memorandum or transferred to the Buyers
after the Closing pursuant to Section 6.2(c).

        1.66 "REGISTRATION STATEMENT" means Medarex's universal shelf
registration statement on Form S-3 (No. 333-52696), filed with the SEC on
December 22, 2000 and declared effective by the SEC on December 22, 2000, and as
amended by Post-Effective Amendment No. 1 filed with the SEC on June 19, 2001
and declared effective on January 22, 2001.

        1.67 "REQUIRED CONSENTS" has the meaning given such term in Section 4.6.

        1.68 "RESOLVED CLAIM" means an Indemnification Claim as to which either
(a) an arbitrator or court having jurisdiction has entered a final judgment,
decision, order or decree that either is not subject to appeal or as to which
notice of appeal has not been timely, filed or served or (b) the Indemnifying
Party has acknowledged and agreed in writing.

        1.69 "SCHEDULED EMPLOYEE" has the meaning given such term in Section
7.1(a).

        1.70 "SEC" means the United States Securities and Exchange Commission.

        1.71 "SECURITIES ACT" means the Securities Act of 1933, as amended.

        1.72 "SELLER DISCLOSURE MEMORANDUM" means the disclosure memorandum
delivered by the Sellers to the Buyers in connection with this Agreement.

        1.73 "START TIME" has the meaning given such term in Section 7.1.

        1.74 "SUBLEASE" has the meaning given such term in Section 8.1(l).

        1.75 "SUBLEASED PREMISES" means the premises leased by Medarex from
Coulter pursuant to the Sublease.

        1.76 "SUBSTITUTE OPTION" has the meaning given such term in the UPT
License Agreement.

        1.77 "TAIL PROVISION" means the provisions of any Proprietary Rights and
Inventions Agreement between any Seller and a Scheduled Employee providing that
such Scheduled Employee (a) shall disclose to one or more Sellers any Invention
made or conceived, reduced to practice or learned by such Scheduled Employee
after the Start Time and (b) creating a presumption that any such Invention was
conceived during such Scheduled Employee's employment or consultancy with a
Seller.


                                      -8-
<PAGE>


        1.78 "TAX" or "TAXES" means all taxes, levies, assessments, tariffs,
imposts and tolls, however denominated, including any interest, penalties, fees
or other additions to such that may become payable in respect thereof, (a)
imposed by any Governmental Entity, for which a Buyer could become liable as
successor to or transferee of the Assets or that could become a Lien on any of
the Assets, which taxes shall include, without limiting the generality of the
foregoing, all sales and use taxes, ad valorem taxes, excise taxes, business
license taxes, occupation taxes, real and personal property taxes, stamp taxes,
environmental taxes, real property gains taxes, transfer taxes, inventory taxes,
payroll and employee withholding taxes, unemployment insurance contributions,
social security taxes, and other governmental charges, and other obligations of
the same or of a similar nature to any of the foregoing, which are required to
be paid, withheld or collected, or (b) any Liability for amounts referred to in
clause (a) as a result of any obligations to indemnify another Person.

        1.79 "THIRD PARTY" means any Person other than a Party or an Affiliate
of the same.

        1.80 "THIRD-PARTY AGREEMENTS" means those agreements between one or more
of the Sellers or any of their predecessors and any Third Party that are listed
on Schedule 2.1 to the Seller Disclosure Memorandum.

        1.81 "TRADE SECRETS" means all right, title and interest in all trade
secrets and trade secret rights arising under Law.

        1.82 "TRADEMARKS" means all right, title and interest in all trademark,
service mark, trade name and trade dress rights arising under the common law,
state law, federal law, and laws of foreign countries, and all right, title, and
interest in all trademark, service mark, trade name, and trade dress
applications and registrations interests throughout the world.

        1.83 "TRANSFERRED INTELLECTUAL PROPERTY RIGHTS" means all Intellectual
Property Rights in the Product Candidates, including the Transferred Patents and
all Trade Secrets that are directly and exclusively related to the Programs and
any Intellectual Property Rights transferred to Buyers pursuant to Section
6.2(c), and except for all Intellectual Property Rights licensed to the Sellers
under the Assigned Contracts.

        1.84 "TRANSFERRED PATENTS" means the Patents listed on Schedule 2.1 to
the Seller Disclosure Memorandum or transferred to the Buyers after the Closing
pursuant to Section 6.2(c).

        1.85 "ULTIMAB HUMAN ANTIBODY DEVELOPMENT SYSTEM TECHNOLOGY" means
Medarex's proprietary technology for the generation of fully human monoclonal
antibodies using (i) any of Medarex's proprietary immunizable transgenic mice
that contain [*] heavy and light [*] inserted into [*] and which are commonly
known as a HuMAb-Mouse(R); (ii) any mice comprising both (A) human [*] developed
by Medarex or otherwise developed through use of Medarex's proprietary HuMAb
Mouse; and (B) human [*] developed by Kirin Brewery Company, Ltd. ("Kirin") or
otherwise developed through use of Kirin's proprietary TC Mouse(TM)

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(as defined below), including, without limitation, any mouse comprising the [*]
described in clause (A) and clause (B) of this clause (ii) that is derived by
(x) crossbreeding the HuMAb Mouse with a TC-Mouse, (y) introducing [*] obtained,
isolated, or derived from a HuMAb Mouse into one or more cells obtained from a
TC-Mouse, or (z) introducing [*] obtained, isolated, or derived from a TC-Mouse
into one or more cells obtained from a HuMAb Mouse; and (iii) any progeny
produced by (or by use of) such transgenic mice described in clauses (i) and
(ii) above. For purposes of this Section 1.85, "TC-MOUSE" shall mean any
immunizable transchomosomic mouse developed by Kirin that contains one or more
human [*] or [*] thereof that include [*] and [*] sequences that provide for
replication outside of mouse [*], and which [*] or [*] comprises an [*] human
[*].

        1.86 "UPT" means any ultra potent toxin or derivative thereof, including
without limitation, any Duocarmycin analog (including without limitation,
Duocarmycin B2 or KW-2189 (both, as defined in the UPT License Agreement)) that
is covered or claimed by the Transferred Intellectual Property Rights or by
Intellectual Property Rights licensed to the Sellers under the Assigned
Contracts.

        1.87 "UPT LICENSE AGREEMENT" has the meaning given such term in Section
8.1(i).

        1.88 "UPT TECHNOLOGY" means all or any part of that technology
transferred to Medarex under this Agreement related to UPTs and the Linker
Technology.

2.      SALE AND PURCHASE.

        2.1 TRANSFER OF ASSETS. Subject to the terms and conditions of this
Agreement, the Sellers shall sell, assign, grant, transfer and deliver (or cause
to be sold, assigned, granted, transferred and delivered) to the Buyers as of
the Closing, and the Buyers shall purchase and accept from the Sellers as of the
Closing, free and clear of all Liens (except as otherwise provided on Schedule
4.4 to the Seller Disclosure Memorandum and other than Assumed Liabilities or
Liens arising under the Assigned Contracts), all of the Sellers' rights, title
and interest in and to the Assets, which do not include the Excluded Assets.

        2.2 TRANSFER OF LIABILITIES. Subject to the terms and conditions of this
Agreement, the Buyers agree, effective as of the Closing, to assume all
Liabilities arising after the Closing under the Assigned Contracts (the "Assumed
Liabilities"); provided, however, that the Buyers shall not assume and the
Assumed Liabilities shall not include any Liabilities that (i) arise from or
relate to any breach by a Seller of any provision of any of the Assigned
Contracts prior to the Closing, (ii) arise from or relate to any material
inaccuracy in the representations and warranties made by each Seller in this
Agreement or any of the Operative Documents or (iii) arise from or relate to the
ownership, use or operation of the Assets by any Seller on or prior to the
Closing.

        2.3 EXCLUDED LIABILITIES. The Buyers shall not by virtue of this
Agreement assume Liability or responsibility for any Liability of the Sellers
that is not included within the definition of Assumed Liabilities (the "Excluded
Liabilities").

        2.4 PURCHASE PRICE. In consideration of the acquisition of the Assets
under Section 2.1, the Buyers will assume the Assumed Liabilities under Section
2.2 and pay to Corixa for the Assets an aggregate purchase price (the "Purchase
Price") consisting of a component to

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be paid in cash or stock during the five-month period following the Closing Date
(the "Guaranteed Component"), a contingent component to be paid in cash or stock
after the Closing (the "Contingent Component"), reimbursement of certain
expenses (the "Reimbursement Component") and a cash component to be paid at the
Closing in respect of the Equipment (the "Equipment Component"), all as provided
in this Section 2.4.

            (a) GUARANTEED COMPONENT. The Guaranteed Component shall consist of
six equal payments (each, a "Monthly Payment") of Three Million Five Hundred
Thousand Dollars ($3,500,000) each (the "Monthly Value"), to be paid in cash, or
at Medarex's election, in shares of fully registered, freely tradeable Medarex
Stock issued under the Registration Statement, with such payments to be made on
the applicable Payment Date. In the event that Medarex decides to make the
Monthly Payment in shares of Medarex Stock (a "Monthly Issuance"), the number of
shares of Medarex Stock to be issued as the Monthly Payment shall be determined
by dividing (y) the Monthly Value by (z) the applicable Base Price. No
fractional shares of Medarex Stock shall be issued in any Monthly Issuance. The
aggregate number of shares of Medarex Stock that Corixa is entitled to receive
pursuant to any Monthly Issuance shall be rounded to the nearest whole number,
with .5 and greater being rounded up. The issuance of the Guaranteed Component
shall be subject to the provisions of Sections 2.4(a)(i), (ii), (iii) and (iv).

                (i) No later than five business days after the end of each
one-month period after a Payment Date on which Medarex makes a Monthly Issuance,
Corixa agrees to provide Medarex with written notice, together with written
documentation evidencing such sales (the "Proceeds Notice") certifying the
number of shares of Medarex Stock that were sold by Corixa during the one month
period following such Payment Date and the Actual Sales Proceeds for such sales.
In the event that Corixa sells all of the Medarex Stock constituting any Monthly
Issuance during the one-month period following the Payment Date for such Monthly
Issuance, the provisions of Section 2.4(a)(ii) shall apply to such Monthly
Issuance. In the event that Corixa does not sell all of the Medarex Stock
constituting any Monthly Issuance during the one-month period following the
Payment Date for such Monthly Issuance, the provisions of Section 2.4(a)(iii)
shall apply to such Monthly Issuance. For purposes of this calculation, the
trade date, rather than the settlement date, shall be used in determining
whether such Monthly Issuance has been sold by Corixa. Further, Corixa agrees
that it shall not engage in any scheme or plan to avoid the application of this
subsection 2.4(a)(i) by retaining nominal amounts of Monthly Issuances, but
shall operate in good faith.

                (ii) If the Actual Sales Proceeds stated on the Proceeds Notice
are less than the Monthly Value, Medarex shall, no later than five business days
after receipt of the Proceeds Notice, pay cash to Corixa by wire transfer of
immediately available funds in an amount equal to the difference between the
Actual Sales Proceeds and the Monthly Value. If the Actual Sales Proceeds stated
on the Proceeds Notice are greater than the Monthly Value, Corixa shall, no
later than five business days after delivery of the Proceeds Notice, pay cash to
Medarex by wire transfer of immediately available funds in an amount equal to
fifty percent (50%) of the difference between the Actual Sales Proceeds and the
Monthly Value.

                (iii) In the event that Corixa does not sell all of the Medarex
Stock constituting any Monthly Issuance during the one month period following
the Payment Date of


                                      -11-
<PAGE>


such Monthly Issuance, no payments contemplated by Section 2.4(a)(ii) shall be
made by either Party.

                (iv) Corixa shall not sell more than the number of shares of
Medarex Stock equal to fifty percent (50%) of the total number of shares
constituting the previous Monthly Issuance in any five-trading-day period.

                (v) Corixa shall not engage in any form of Hedging Transactions
in Medarex Stock at any time during the first six months after the Closing Date.

            (b) CONTINGENT COMPONENT.

                (i) Medarex shall act in good faith to obtain [*] agreement to
[*] (the "[*]"), as promptly after the Closing as is, in Medarex's judgment in
its sole discretion, commercially reasonable and on terms that, in Medarex's
judgment in its sole discretion, [*] required to be [*] to [*] in connection
with the [*]; provided, however, that Medarex shall [*] to [*] to [*] the [*] no
later than [*] after the Closing Date. Medarex shall notify Corixa as promptly
as practicable and in any event no later than five business days after Medarex
and [*] of the [*] and material [*] of the [*] (the "[*] Notice").

                (ii) Upon the earliest to occur of (A) ten business days after
the date on which [*] and Medarex [*] if no Offset Consideration is [*] in
connection with the [*], (B) ten business days after Corixa delivers to Medarex
notice of its Offset Election in the event that [*] Consideration in connection
with the [*] and (C) December 31, 2004 (subject to extension for such period
after Medarex has delivered a [*] that provides for Offset Consideration but
Corixa has not yet delivered notice of its Offset Election) (the "Contingent
Payment Date"), Medarex shall pay to Corixa the Contingent Component in the
amount of Six Million Dollars ($6,000,000), less the value of any Cash Offsets
(as defined below) resulting from the [*].

                (iii) Medarex, at its election, may pay the Contingent Component
in cash or shares of fully registered, freely tradeable Medarex Stock issued
under the Registration Statement. In the event that Medarex elects to pay the
Contingent Component in shares of Medarex Stock, Medarex shall deliver to Corixa
a certificate representing such Medarex Stock no later than the Contingent
Payment Date. For purposes of this Section 2.4(b)(iii), shares of Medarex Stock
shall be valued according to the Base Price. No fractional shares of Medarex
Stock shall be issued in the Contingent Component. The aggregate number of
shares of Medarex Stock that Corixa shall be entitled to receive pursuant to
this Section 2.4(b)(iii) shall be rounded to the nearest whole number, with .5
and greater being rounded up.

                (iv) For purposes of this Section 2.4, the "Cash Offset" shall
be determined as follows. In the event that no [*] on or before December 31,
2004, the Cash Offset shall equal Three Million Dollars ($3,000,000). In the
event the [*] on or before December 31, 2004, the Cash Offset shall equal the
lesser of (y) Six Million Dollars ($6,000,000) and (z) the sum of the following
amounts:

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                    (1) the full dollar amount of [*] in connection with the
[*], up to a maximum of Three Million Dollars ($3,000,000);

                    (2) fifty percent (50%) of the dollar amount of [*] in
connection with the [*], to the extent the value of any such payments and
issuances exceeds Three Million Dollars ($3,000,000); and

                    (3) One Million Dollars ($1,000,000) for each Offset
Election made by Corixa pursuant to Section 2.4(b)(v).

                (v) Subject to Section 2.4(b)(vi), if in connection with the
[*], Medarex either (A) [*] a [*] with the same or more favorable to [*]
pursuant to the [*] or (B) [*]that are Materially Discounted[*] (such [*],
"Offset Consideration"), one of Corixa's License Options shall be revoked.
Notwithstanding the foregoing, Corixa may elect, in lieu of having such License
Option revoked, to increase the Cash Offset by One Million Dollars ($1,000,000)
(an "Offset Election"); provided, however, that Corixa shall not be entitled to
make any Offset Election to the extent the Cash Offset exceeds or would, as a
result of such Offset Election, exceed Six Million Dollars ($6,000,000);
provided, further, that in the event the number of License Options revoked under
this Section 2.4(b) equals six (6), Corixa shall be deemed automatically to have
made an Offset Election for each [*]. Corixa's Offset Election shall be made no
later than ten business days following delivery of the [*] by Medarex.

                (vi) Notwithstanding anything to the contrary herein, in no
event shall (A) more than six (6) License Options be revoked pursuant to this
Section 2.4, (B) more than two (2) License Options per year be revoked, (C) any
Licenses be revoked hereunder or in connection herewith and (D) the sum of the
Cash Offset plus the License Revocation Value (the "Total Offset Value") exceed
Nine Million Dollars ($9,000,000). In the event that the Total Offset Value
would exceed Nine Million Dollars ($9,000,000), Corixa shall determine the
number of License Options to be revoked and the amount of the Cash Offset,
provided that (x) the number of License Options to be revoked shall not exceed
the number that otherwise would have been revoked pursuant to Section 2.4(b)(v)
absent any Offset Election, (y) the Total Offset Value shall equal Nine Million
Dollars ($9,000,000) and (z) the dollar amount of the Cash Offset shall not be
less than the sum of the dollar amounts specified in Section 2.4(b)(iv)(1) and
Section 2.4(b)(iv)(2).

                (vii) In the event that one of Corixa's License Options is
revoked pursuant to Section 2.4, Corixa may exercise a Substitute Option
pursuant to the terms set forth in the UPT License Agreement.

            (c) REIMBURSEMENT COMPONENT. The Reimbursement Component shall
consist of certain expenses paid by the Sellers to be reimbursed to Corixa by
Medarex at the Closing, which expenses are set forth on Schedule 2.4(c) to the
Seller Disclosure Memorandum.

            (d) EQUIPMENT COMPONENT. The Equipment Component shall be equal to
Two Million Five Hundred Thousand Dollars ($2,500,000).

        2.5 ALLOCATION OF PURCHASE PRICE. The Parties agree that the Purchase
Price shall be allocated among the Assets in the manner set forth on Schedule
2.5 to the Seller Disclosure

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                                      -13-
<PAGE>


Memorandum (the "Allocation"). The Allocation will be conclusive and binding
upon the Parties for tax purposes, and neither Party will make any statement or
declaration to any taxing authority that is inconsistent with the Allocation,
except as provided below. Neither Party will take or permit any of its
Affiliates or representatives to take any position on any tax return, with any
taxing authority or in any judicial tax proceeding that is inconsistent with the
Allocation except as required by a final determination within the meaning of
Section 1313(a) of the Internal Revenue Code or any equivalent provision of any
applicable Law. Each Party will promptly provide the other Party with any
additional information required to complete Form 8594 if the filing of such form
is required. Each Party will timely notify the other Party, and will timely
provide the other Party with assistance, in the event of an examination, audit
or other proceeding regarding the Allocation.

3.      CLOSING AND FUTURE PAYMENTS.

        3.1 CLOSING. Subject to the terms and conditions of this Agreement, the
closing of the sale of the Assets and the consummation of the other transactions
contemplated hereby (the "Closing") shall take place on the date hereof, at 9:00
a.m. local time at the offices of Orrick, Herrington & Sutcliffe LLP at 719
Second Avenue, Suite 900, Seattle, Washington, or at such other time, date or
place as the Parties may mutually agree upon in writing (the "Closing Date").

        3.2 ACTIONS AT THE CLOSING. At the Closing, the Sellers shall deliver
the Assets to Medarex (other than the Belgian Assets and other than the physical
assets to be delivered after Closing, as contemplated by Section 6.8), the
Sellers shall deliver the Belgian Assets to Medarex Belgium, Medarex shall
deliver to Corixa the components of the Purchase Price to be delivered at
Closing, and the Buyers and the Sellers shall take such actions and execute and
deliver the Operative Documents and such other agreements, instruments and
documents as are necessary or appropriate to effect the transactions
contemplated by this Agreement in accordance with its terms, including, without
limitation, the following:

            (a) TRANSFER INSTRUMENTS. Each applicable Seller shall deliver to
each applicable Buyer (i) a general bill of sale substantially in the form
attached as Exhibit A (the "Bill of Sale") with respect to the Assets (other
than the Belgian Assets); (ii) an assignment and assumption agreement
substantially in the form attached as Exhibit B1 (the "Assignment and Assumption
Agreement") with respect to the Assigned Contracts (other than the Assigned
Contracts included with the Belgian Assets); (iii) an assignment and assumption
agreement substantially in the form attached as Exhibit B2 with respect to the
Assigned Contracts included in the Belgian Assets (the "Belgian Assignment and
Assumption Agreement"); and (iv) an assignment of patents substantially in the
form attached as Exhibit C (the "Assignment of Patents") with respect to the
Transferred Patents, in each case duly executed by the applicable Seller, and in
the aggregate assigning to the Buyers all of the Sellers' right, title and
interest in and to the Assets.

            (b) PURCHASE PRICE. Medarex shall deliver the Purchase Price to
Corixa as follows:

                (i) GUARANTEED COMPONENT. If Medarex elects to pay the first
Monthly Payment in cash, Medarex shall pay to Corixa the first Monthly Payment
by wire


                                      -14-
<PAGE>


transfer of immediately available funds to such bank account of Corixa as Corixa
designated prior to the execution of this Agreement. If Medarex elects to make
the first Monthly Payment by issuance of Medarex Stock, Medarex shall deliver to
its transfer agent, with a copy to Corixa, an irrevocable instruction letter
(the "Irrevocable Instruction Letter") to issue and deliver to Corixa, as soon
as practicable and no later than three (3) business days after the Closing Date,
a stock certificate representing the shares of Medarex Stock constituting such
first Monthly Payment. If Medarex elects to make any other Monthly Payment by
issuance of Medarex Stock, Medarex shall deliver to Corixa the certificate
representing such shares of Medarex Stock on the applicable Payment Date.

                (ii) REIMBURSEMENT COMPONENT. Medarex shall pay to Corixa the
Reimbursement Component by wire transfer of immediately available funds to such
bank account of Corixa as Corixa designated prior to the execution of this
Agreement.

                (iii) EQUIPMENT COMPONENT. Medarex shall pay to Corixa the
Equipment Component by wire transfer of immediately available funds to such bank
account of Corixa as Corixa designated prior to the execution of this Agreement.

            (c) SELLER DOCUMENTS. At the Closing, the Sellers shall deliver to
the Buyers any and all documents required to be delivered by the Sellers under
Section 8 and any other closing documents reasonably requested by the Buyers.

            (d) BUYER DOCUMENTS. At the Closing, the Buyers shall deliver to the
Sellers any and all documents required to be delivered by the Buyers under
Section 8 and any other closing documents reasonably requested by the Sellers.

4.      REPRESENTATIONS AND WARRANTIES OF SELLERS.

        Except as otherwise set forth in the Seller Disclosure Memorandum, in
order to induce the Buyers to enter into and perform this Agreement, the Sellers
represent and warrant to the Buyers as follows in this Section 4:

        4.1 ORGANIZATION AND GOOD STANDING. Each of Corixa and Coulter is a
corporation duly organized, validly existing and in good standing under the laws
of the state of Delaware. Corixa Belgium is a corporation duly organized,
validly existing and in good standing under the laws of Belgium.

        4.2 AUTHORITY; AUTHORIZATION; ENFORCEABILITY. Each Seller has full
corporate power and authority to execute and deliver this Agreement and each of
the Operative Documents to which it is a party, to perform its obligations
hereunder and thereunder and to consummate the transactions contemplated hereby
and thereby. The execution and delivery by each Seller of this Agreement and
each of the Operative Documents to which it is a party, the performance by each
Seller of its obligations hereunder and thereunder and the consummation by each
Seller of the transactions contemplated hereby and thereby have been duly
authorized by all necessary corporate action of such Seller. This Agreement and
each of the Operative Documents has been duly executed and delivered by each
Seller that is a party to such Operative Document. This Agreement and each of
the Operative Documents constitutes a valid and binding obligation of each
Seller that is a party to such Operative Document, enforceable against such
Seller in


                                      -15-
<PAGE>


accordance with its terms, except as such enforceability may be limited by
bankruptcy, insolvency, reorganization or similar Laws affecting creditors'
rights generally or by general equitable principles.

        4.3 NO DEFAULT OR VIOLATION. The execution, delivery and performance by
each Seller of this Agreement and each of the Operative Documents to which it is
a party, the performance of its obligations hereunder and thereunder, and the
consummation of the transactions contemplated hereby and thereby do not and will
not (with or without the giving of notice or lapse of time, or both) (a)
constitute a material violation of any provision of Law or any Order applicable
to such Seller; (b) require any consent, approval or authorization of, or
declaration, filing or registration with, any Governmental Entity; (c) result in
a default under, or acceleration or termination of, or the creation in any party
of the right to accelerate, terminate, modify or cancel, any material agreement,
lease, note or other contract to which such Seller is a party or by which it is
bound or to which any of the Assets are subject (assuming receipt of the
Required Consents); (d) conflict with or result in a breach of or constitute a
default under any provision of the certificate of incorporation or bylaws (or
similar organizational documents) of such Seller; or (e) result in the
imposition or creation of any Lien on or with respect to any of the Assets
(other than Liens arising under the Assigned Contracts).

        4.4 TITLE TO ASSETS. The Sellers have good and marketable title in and
to the Assets. All of the Assets are owned by the Sellers free and clear of all
Liens, except as otherwise provided in the Assigned Contracts, and upon
consummation of the transactions contemplated hereby, the Buyers will have
acquired all of the Sellers' rights, title and interest in and to the Assets,
free and clear of all Liens, and except for Liens created by or imposed on the
Buyers after the Closing through no act or fault of the Sellers. No Seller has
made any sale or assignment that would conflict with the sale and assignment of
its rights in and to the Assets to the Buyers as contemplated by this Agreement.
The Assets constitute all of the assets, both tangible and intangible, wherever
located and whether or not required to be reflected on a balance sheet prepared
in accordance with GAAP, used by Sellers in the conduct of the Programs. The
Sellers make no representation or warranty regarding the probable commercial
success or profitability of or resulting from the ownership, use, operations,
manufacturing, formulating, packaging, marketing or distribution of the Product
Candidates after the Closing.

        4.5 LICENSES AND PERMITS; COMPLIANCE WITH LAW.

            (a) The Programs are in compliance in all material respects with all
Laws relating to the Product Candidates and the Programs, including without
limitation all such Laws relating to registration, use or manufacture of the
Product Candidates (at their current level of development and use) and
certification of the Facility. None of the Product Candidates are or have been
the subject of any clinical trials and none of the Sellers have administered any
of the Product Candidates in any human subject. There is no investigation or
inquiry to which any Seller is a party pending or, to any Seller's knowledge,
threatened relating to the Assets and their compliance with applicable Laws. The
Sellers have not received, at any time in the past three years, any written
notice from any Governmental Entity or other Person regarding any actual or
alleged violation of, or failure to comply with, any Law applicable to the
ownership or use of any of the Assets. To the knowledge of Sellers, no event has
occurred, and no condition or circumstance exists, that would (with or without
notice or lapse of time) constitute or result


                                      -16-
<PAGE>


directly or indirectly in a violation by the Sellers of, or a failure on the
part of the Sellers to comply with, any Law applicable to the ownership or use
of any of the Assets.

            (b) Schedule 4.5(b) to the Seller Disclosure Memorandum sets forth a
list of all material Governmental Authorizations held by Sellers with respect to
the Assets. The Governmental Authorizations identified in Schedule 4.5(b) to the
Seller Disclosure Memorandum constitute all of the Governmental Authorizations
necessary to permit the Sellers to own and use the Assets in the manner in which
they are currently owned and used; provided, however that notwithstanding
anything to the contrary herein, such Governmental Authorizations shall not be
deemed to be part of the Assets and shall not be transferred to the Buyers
pursuant to this Agreement. Each Governmental Authorization identified on
Schedule 4.5(b) to the Seller Disclosure Memorandum is valid and in full force
and effect. The Sellers are and at all times have been in compliance in all
material respects with all of the terms and requirements of each Governmental
Authorization identified on Schedule 4.5(b) to the Seller Disclosure Memorandum.
The Sellers have not received, at any time in the past three years, any written
notice from any Governmental Entity or any other Person regarding any actual or
alleged violation of or failure to comply with the terms of any such
Governmental Authorization or (ii) any actual or threatened revocation,
withdrawal, suspension, cancellation, termination or modification of any
Governmental Authorization identified on Schedule 4.5(b) to the Seller
Disclosure Memorandum.

        4.6 ASSIGNED CONTRACTS. Schedule 2.1 to the Seller Disclosure Memorandum
sets forth a list of all of the contracts related to the Assets, including the
Product Candidates and the Programs that are to be assigned to the Buyers at the
Closing (the "Assigned Contracts"). All the Assigned Contracts are valid,
binding and enforceable in accordance with their terms by and against each
Seller that is a party to such Assigned Contract and, to the knowledge of each
Seller, each other party thereto, and are in full force and effect. Each Seller
has performed in all material respects all obligations imposed on it thereunder,
and no Seller nor, to the knowledge of any Seller, any other party thereto is in
default thereunder. To the knowledge of each Seller, and except as would not
reasonably be expected to have a Program Material Adverse Effect, no event has
occurred, and no circumstance or condition exists, that would (with or without
notice or lapse of time) (i) constitute a default by any Seller or, to the
knowledge of any Seller, any other party thereunder, (ii) result in a violation
or breach of any of the provisions of the Assigned Contracts, (iii) give any
Person the right to declare a default or exercise any remedy for default under
the Assigned Contracts or (iv) give any Third Party the right to cancel,
terminate or modify any of the Assigned Contracts (except to the extent any such
Assigned Contract is by its terms terminable, cancelable or modifiable by such
Third Party upon prior notice or after the expiration of a specified term). The
Sellers have not received any written notice regarding any actual or alleged
violation, breach or default under any of the Assigned Contracts. As of the date
of this Agreement, the Sellers are not directly and actively engaged in any
renegotiation of any amounts paid or payable to the Sellers under any of the
Assigned Contracts or any other material term or material provision of any of
the Assigned Contracts. True and complete copies of each Assigned Contract have
been delivered to the Buyers by the Sellers, and there is no legally enforceable
agreement (written or oral) between any Seller and any other party to any
Assigned Contract that amends, modifies or interprets or purports to amend,
modify or interpret the terms of any Assigned Contract (except for the Required
Consents). Schedule 4.6 to the Seller Disclosure Memorandum sets forth a list of
all Assigned Contracts that require the consent or


                                      -17-
<PAGE>


waiver of any party to such Assigned Contract as a result of the transactions
contemplated hereby (the "Required Consents"); provided, however, that certain
of the consents will not be obtained prior to the Closing Date, as set forth on
Schedule 4.3 to the Seller Disclosure Memorandum).

        4.7 INTELLECTUAL PROPERTY.

            (a) Schedule 2.1 to the Seller Disclosure Memorandum lists (i) all
Transferred Patents, including the jurisdictions in which each such Transferred
Patent has been issued or registered or in which any application for such
issuance and registration has been filed and (ii) all material licenses,
sublicenses and other agreements as to which any Seller is a party and pursuant
to which any Person is authorized to use, practice or exploit in any manner any
Transferred Intellectual Property Rights or Licensed Intellectual Property
Rights or to make, have made, use or sell any Product Candidate. The Sellers are
the sole and exclusive owners, with all right, title and interest in and to
(free and clear of any Liens) the Transferred Intellectual Property, and are the
exclusive or nonexclusive, as applicable, pursuant to the terms of the Assigned
Contracts, licensees of, the Licensed Intellectual Property Rights. The Sellers
have legally enforceable rights to the use of such Transferred Intellectual
Property Rights and Licensed Intellectual Property Rights or the material
covered by such Transferred Intellectual Property Rights and Licensed
Intellectual Property Rights in connection with the Programs. All Transferred
Intellectual Property Rights will be fully transferable, alienable and
licensable by the Buyers, without restriction and without payment of any kind to
any third party.

            (b) To the knowledge of each Seller, there is no unauthorized use,
disclosure, infringement or misappropriation of any Transferred Intellectual
Property Rights or any Licensed Intellectual Property Rights. None of the
Sellers has brought against any Person any Proceeding for infringement of the
Transferred Intellectual Property Rights or Licensed Intellectual Property
Rights or breach of any license or agreement involving the Transferred
Intellectual Property Rights or Licensed Intellectual Property Rights. To the
knowledge of each Seller, all issued Transferred Patents are valid and existing
and there is no claim pending or, to the knowledge of any Seller, threatened by
any Person challenging the ownership, validity or effectiveness of any issued
Transferred Patents. To the knowledge of each Seller, no Person has made any
claim regarding ownership of the Licensed Intellectual Property other than the
Persons from whom the Licensed Intellectual Property has been licensed by the
Seller. The conduct of the Programs, the manufacture, use, sale, import, export
or offer for sale of any of the Product Candidates and the use, practice or
exploitation of any of the Transferred Intellectual Property Rights and the
Licensed Intellectual Property Rights does not infringe on or conflict with, in
any way, any license or Intellectual Property Right of any Person in a way that,
individually or in the aggregate, would have a Program Material Adverse Effect.
There are no pending or, to the knowledge of any Seller, threatened interference
actions, Proceedings, re-examinations, oppositions or nullities involving any
Transferred Patents, except such as may have been commenced by one or more
Sellers. All filing, examination and maintenance fees required to be paid as of
the Closing with respect to the Transferred Patents have been paid. All such
Transferred Patents are currently in compliance with formal legal requirements
(including payment of filing, examination and maintenance fees and proofs of
use) and are not subject to any unpaid maintenance fees or taxes or actions
falling due within ninety (90) days after the Closing.


                                      -18-
<PAGE>


            (c) All employees and consultants who contributed to the discovery
or development of any Transferred Intellectual Property Rights did so either (i)
within the scope of his or her employment relations with a Seller such that, in
accordance with applicable Law, all Intellectual Property Rights arising from
such employment relationship became the exclusive property of a Seller or (ii)
pursuant to valid written agreements assigning to a Seller all Intellectual
Property Rights arising from his or her employment or consulting relationship.
All Scheduled Employees have executed Corixa's standard form of inventions
agreement, substantially in the form provided to the Buyers.

            (d) Each Seller has taken all commercially reasonable and
appropriate steps to protect and preserve the confidentiality of its Trade
Secrets related to Transferred Intellectual Property Rights and any Trade
Secrets of a Third Party related to the Licensed Intellectual Property Rights,
except as would not reasonably be expected to have an Asset Material Adverse
Effect. Each Seller has a policy requiring each employee, consultant and
independent contractor to execute a proprietary information and confidentiality
agreement substantially in the form provided to Medarex. All current (and, to
the knowledge of each Seller, all former) employees, consultants and independent
contractors of each Seller have executed such an agreement. All use, disclosure
or appropriation by or to another Person of the Trade Secrets related to the
Transferred Intellectual Property Rights and of the Trade Secrets of a Third
Party related to the Licensed Intellectual Property Rights has been pursuant to
the terms of a written agreement between a Seller and such other Person, except
as, individually or in the aggregate, would not reasonably be expected to have a
Program Material Adverse Effect.

        4.8 LITIGATION; OTHER CLAIMS. There are no Proceedings against any
Seller relating to any of the Assets that are currently pending or, to the
knowledge of any Seller, threatened at law or in equity before or by any
Governmental Entity, or that challenge or seek to prevent, make illegal, enjoin,
alter, delay or otherwise interfere with any of the transactions contemplated
hereby or by the Operative Documents. To the knowledge of the Sellers, no event
has occurred and no claim, dispute or other condition or circumstance exists,
that might directly or indirectly give rise to or serve as a basis for the
commencement of any such Proceeding. There is no Order to which any of the
Assets is subject. No Seller is in default under or with respect to any Order of
any court or any Governmental Entity that could reasonably be expected to have a
Program Material Adverse Effect. To the knowledge of each Seller, there is no
proposed Order that, if issued or otherwise put into effect, (a) would have an
Asset Material Adverse Effect, a Program Material Adverse Effect or a material
adverse effect on the ability of the Sellers to perform any covenant or
obligation under this Agreement or the Operative Documents, or (b) would have
the effect of preventing, delaying, making illegal or otherwise interfering with
the transactions contemplated by this Agreement and the Operative Documents.

        4.9 BROKERS AND FINDERS. None of the Sellers, their Affiliates nor any
of their officers, directors or employees has employed any broker or finder or
incurred any liability for any brokerage fee, commission or finder's fee in
connection with the transactions contemplated by this Agreement.

        4.10 FAIR CONSIDERATION; NO FRAUDULENT CONVEYANCE. The sale of the
Assets pursuant to this Agreement is made in exchange for fair and equivalent
consideration and is not subject to any bulk sales or similar Law. None of the
Sellers is now insolvent and none will be


                                      -19-
<PAGE>


rendered insolvent by the sale, transfer and assignment of the Assets pursuant
to the terms of this Agreement. None of the Sellers is entering into this
Agreement or any of the other agreements referenced in this Agreement with the
intent to defraud, delay or hinder its creditors, and the consummation of the
transactions contemplated by this Agreement, and the other agreements referenced
by this Agreement, will not have any such effect. The transactions contemplated
in this Agreement or any agreements referenced in this Agreement will not
constitute a fraudulent conveyance, or otherwise give rise to any right of any
creditor of any Seller to any of the Assets after the Closing.

        4.11 EMPLOYEE AND LABOR MATTERS.

            (a) None of the Sellers is a party to or bound by, and have never
been a party to or bound by, any union contract, collective bargaining agreement
or similar labor contract.

            (b) To the knowledge of each Seller, no Scheduled Employee intends
to terminate his or her employment and no Scheduled Employee is a party to or is
bound by any confidentiality agreement, noncompetition agreement or other
contract (with any Person) that could reasonably be expected to have a material
adverse effect on the performance by such employee of any of his or her duties
or responsibilities (A) as an employee of Sellers in connection with the
Programs as they are currently operated by the Sellers or (B) as a prospective
employee of Medarex in connection with the Programs assuming the Programs are
operated in the same manner as they are currently operated by the Sellers. Each
of the Scheduled Employees is employed by Sellers on an "at will" basis and none
of the Scheduled Employees has any employment agreement or other agreement for
services that contains severance or termination pay Liabilities.

            (c) There has never been any slowdown, work stoppage, labor dispute
or union organizing activity, or any similar activity or dispute, affecting the
Sellers or any of their employees, and no Person has threatened to commence any
such slowdown, work stoppage, labor dispute or union organizing activity or any
similar activity or dispute.

            (d) To the knowledge of each Seller, there are no threatened or
pending Proceedings alleging claims against a Seller brought by any Scheduled
Employee relating in any way to their employment with such Seller, and no Seller
has received any demand letters, civil rights charges, suits or drafts of suits
with respect to claims made, or notice of any governmental or administrative
complaints made, by any of the Scheduled Employees.

        4.12 EQUIPMENT. The Buyers expressly acknowledge that the Sellers make
no representations and warranties of any kind, express or implied, regarding the
condition of the Equipment, its merchantability, or its fitness for a particular
purpose. Sellers have used commercially reasonable efforts to remove all
external, removable contamination by Materials of Environmental Concern;
provided, however, that the Buyers expressly acknowledge that certain of the
Equipment is contaminated with nonremovable Materials of Environmental Concern
and accept the Equipment in such condition. To the extent permitted by any
manufacturer of the Equipment, the Sellers assign to Medarex any manufacturer's
warranties for the Equipment.


                                      -20-
<PAGE>


5.      REPRESENTATIONS AND WARRANTIES OF THE BUYERS.

        In order to induce the Sellers to enter into and perform this Agreement,
the Buyers represent and warrant to the Sellers as follows in this Section 5:

        5.1 ORGANIZATION AND GOOD STANDING. Medarex is a corporation duly
organized, validly existing and in good standing under the laws of the state of
New Jersey. Medarex Belgium is an entity in the course of (a) being incorporated
pursuant to Article 60 of the Belgian Companies Act and (b) being registered
with the Registry of Commerce of Brussels. The registered office of Medarex
Belgium shall be located at 1170 Brussels, Luchtschiplaan 8 box 2.

        5.2 AUTHORITY; AUTHORIZATION; ENFORCEABILITY. Medarex has full corporate
power and authority to execute and deliver this Agreement and each of the
Operative Documents, to perform its obligations hereunder and thereunder and to
consummate the transactions contemplated hereby and thereby. The execution and
delivery by the Buyers of this Agreement and each of the Operative Documents,
the performance by the Buyers of its obligations hereunder and thereunder and
the consummation by the Buyers of the transactions contemplated hereby and
thereby have been duly authorized by all necessary corporate action of Medarex.
This Agreement and each of the Operative Documents has been, duly executed and
delivered by the Buyers. This Agreement and each of the Operative Documents to
which Medarex is a party constitutes a valid and binding obligation of Medarex,
enforceable against Medarex in accordance with its terms, except as such
enforceability may be limited by bankruptcy, insolvency, reorganization or
similar Laws affecting creditors' rights generally or by general equitable
principles.

        5.3 NO DEFAULT OR VIOLATION. The execution, delivery and performance by
each Buyer of this Agreement and each of the Operative Documents to which it is
a party, the performance of its obligations hereunder and thereunder, and the
consummation of the transactions contemplated hereby and thereby do not and will
not (with or without the giving of notice or lapse of time, or both) (a)
constitute a material violation of any provision of Law or any Order applicable
to such Buyer; (b) require any consent, approval or authorization of, or
declaration, filing or registration with, any Governmental Entity, except the
filing of the Prospectus Supplement with the SEC and the formation of Medarex
Belgium as contemplated by Section 6.9; (c) result in a default under, or
acceleration or termination of, or the creation in any party of the right to
accelerate, terminate, modify or cancel, any material agreement, lease, note or
other contract to which such Buyer is a party or by which it is bound; or (d)
conflict with or result in a breach of or constitute a default under any
provision of the Restated Certificate of Incorporation or Amended and Restated
Bylaws of Medarex.

        5.4 VALID ISSUANCE; FREELY TRADEABLE SHARES. Medarex has a sufficient
number of authorized and unissued shares of Medarex Stock reserved for issuance
to complete the transactions contemplated by this Agreement. The Medarex Stock
that constitutes the Guaranteed Component issued at the Closing Date has been,
and the Medarex Stock that constitutes the Guaranteed Component and the
Contingent Component (if any) to be issued after the Closing Date will be, duly
authorized. Upon consummation of the transactions contemplated by this
Agreement, or in the case of Medarex Stock constituting the Contingent Component
upon issuance of such stock pursuant to the terms of this Agreement, the Medarex
Stock issued to


                                      -21-
<PAGE>



Corixa will be validly issued, fully paid and nonassessable, and will be freely
tradeable under the Securities Act on Nasdaq without any volume or other
restrictions thereon (except as provided in Section 2.4) and without any
registration or qualification of the resale thereof by Medarex or Corixa.

        5.5 CAPITALIZATION; NASDAQ LISTING. The authorized capital stock of
Medarex consists of 200,000,000 shares of Medarex Stock, par value $.01 per
share, and 2,000,000 shares of preferred stock, par value $.01 per share. As of
April 30, 2002, (a) 73,002,661 shares of Medarex Stock were issued and
outstanding, (b) options to purchase 6,915,381 shares of Medarex Stock were
outstanding, (c) no warrants to purchase shares of Medarex Stock were
outstanding and (d) no shares of preferred stock of Medarex were issued and
outstanding. The Medarex Stock is quoted and traded on Nasdaq, no suspension of
trading in the Medarex Stock is in effect or, to the Buyers' knowledge,
threatened, and the Medarex Stock meets the criteria for listing and trading on
Nasdaq.

        5.6 REGISTRATION STATEMENT; MEDAREX SEC REPORTS.

            (a) The Registration Statement has become effective under the
Securities Act, and no stop order proceedings with respect thereto have been
instituted or are pending or threatened under the Securities Act and, to the
Buyers' knowledge, no such proceedings are contemplated.

            (b) Medarex has previously made available (via EDGAR) to Corixa a
true and complete copy of its annual report on Form 10-K for the year ended
December 31, 2001, its quarterly report on Form 10-Q for the quarter ended March
31, 2002 and all other documents filed by Medarex with the SEC under the
Exchange Act between the date of filing of such annual report and the date
hereof (the "Medarex SEC Reports"). As of their respective dates, the
Registration Statement, the Prospectus Supplement and the Medarex SEC Reports
were prepared in all material respects in accordance with the Securities Act or
the Exchange Act, as the case may be, and as of the date hereof, none of
Registration Statement, the Prospectus Supplement or the Medarex SEC Reports
contains any untrue statement of a material fact or omits to state a material
fact required to be stated therein or necessary in order to make statements
therein, in light of the circumstances in which they were made, not materially
misleading. The consolidated financial statements of Medarex included in the
Medarex SEC Reports complied as to form in all material respects with the
published rules and regulations of the SEC with respect thereto, were prepared
in accordance with GAAP applied on a consistent basis throughout the periods
indicated (except as may be indicated in the notes thereto) and fairly presented
in all material respects the consolidated financial position of Medarex and its
subsidiaries as of the respective dates thereof and the consolidated results of
Medarex's operations and cash flows for the periods indicated. As of the date
hereof, Medarex has no Liabilities that are not fully reflected or reserved
against in its most recently publicly filed balance sheet and that would be
required under GAAP to be reflected or reserved, except (a) Liabilities incurred
since the date of such balance sheet in the ordinary course of business, (b)
Liabilities arising out of the transactions contemplated by this Agreement and
(c) Liabilities that would not result in a Buyer Material Adverse Effect.


                                      -22-
<PAGE>


        5.7 ABSENCE OF CERTAIN CHANGES. Since December 31, 2001 and as of the
date hereof, except as reflected in the Medarex SEC Reports, the Buyers have not
(a) suffered any Buyer Material Adverse Effect; (b) taken any action or entered
into or agreed to enter into any transaction, agreement or commitment other than
in the ordinary course of business; (c) purchased or sold, transferred or
otherwise disposed of any of its material properties or assets other than sales
of inventory in the ordinary course of business; (d) made any change in
accounting methods or practices or internal control procedure (other than as
required by GAAP); or (e) agreed, in writing or otherwise, to take any action
described in this Section 5.7, except as disclosed in the Medarex SEC Reports
filed prior to the date of this Agreement.

        5.8 BROKERS AND FINDERS. None of the Buyers, their Affiliates nor any of
their officers, directors or employees has retained any broker or finder or
incurred any liability for any brokerage fee, commission or finder's fee in
connection with the transactions contemplated by this Agreement.

        5.9 PROSPECTUS DELIVERY. Medarex has delivered to Corixa the Prospectus
Supplement.

6.      COVENANTS.

        6.1 ACCESS TO INFORMATION.

            (a) If, after the Closing, in order properly to operate the Assets
or prepare documents or reports required to be filed with Governmental Entities
or Medarex's consolidated financial statements, it is necessary that Medarex
obtain additional information within any Seller's possession relating to the
Assets (other than the Data and Records, which are covered by Sections 6.3(a)
and (b)), such Seller will furnish or cause their representatives to furnish
such information, at reasonable times and upon reasonable notice, to Medarex and
its authorized representatives. Each Seller shall maintain and make available
the information and records specified in this Section 6.1(a) for a period of
five (5) years after the Closing Date.

            (b) If, after the Closing, in order to properly prepare documents or
reports required to be filed with Governmental Entities or Corixa's consolidated
financial statements, it is necessary that Corixa obtain additional information
within Medarex's possession relating to the Assets (other than the Data and
Records, which are covered by Sections 6.3(a) and (b)), Medarex will furnish or
cause its representative to furnish, at reasonable times and upon reasonable
notice, such information to Corixa and its authorized representatives. Medarex
shall maintain and make available the information and records specified in this
Section 6.1(b) for a period of five (5) years after the Closing Date.

        6.2 FURTHER ACTION; COMMERCIALLY REASONABLE EFFORTS.

            (a) Upon the terms and subject to the conditions hereof, each of the
Parties shall use commercially reasonable efforts to take, or cause to be taken,
all appropriate action, and to do, or cause to be done, all things necessary,
proper or advisable under applicable Laws to consummate and make effective the
transactions contemplated hereby. In the event that at any time after the
Closing any further action is necessary or desirable to carry out the purposes
of this


                                      -23-
<PAGE>


Agreement or the other Operative Documents, each Party shall use commercially
reasonable efforts to promptly take all such action.

            (b) Each Seller agrees that, if reasonably requested by a Buyer, it
will cooperate with the Buyers, at the Buyers' expense, in enforcing the terms
of any agreements between any Seller and any Third Party involving the Programs
or the Product Candidates, including, without limitation, terms relating to
confidentiality and the protection of the Transferred Intellectual Property
Rights or the Licensed Intellectual Property Rights. In the event that a Buyer
is unable to enforce its Transferred Intellectual Property Rights against a
Third Party as a result of a rule or Law barring enforcement of such rights by a
transferee of such rights, each Seller agrees to reasonably cooperate with such
Buyer by assigning to such Buyer such rights as may be required by such Buyer to
enforce its Transferred Intellectual Property Rights in its own name. If such
assignment still does not permit such Buyer to enforce its Transferred
Intellectual Property Rights against the Third Party, each Seller agrees to
initiate proceedings against such Third Party in such Seller's name, provided
that such Buyer shall be entitled to participate in such proceedings and
provided further that such Buyer shall be responsible for the expenses,
including the wage and benefit expenses of such Seller's employees, that may be
incurred by such Seller related to such proceedings.

            (c) To the extent that any Seller or any Buyer identifies assets
after the Closing that were not included on Schedule 2.1 to the Seller
Disclosure Memorandum (other than assets identified on Schedule 4.4 to the
Seller Disclosure Memorandum), but the absence of which on Schedule 2.1 to the
Seller Disclosure Memorandum would constitute a breach or inaccuracy of the
representation contained in the second-to-last sentence of Section 4.4, such
Seller shall transfer all of its right, title and interest in such assets to the
Buyers, with such transfer to be completed as promptly as commercially
reasonable after such identification.

        6.3 RELATED DATA AND RECORDS.

            (a) The Parties will cooperate and work together to allocate the
Data, Records and Materials in accordance with this Section 6.3. If certain
Data, Records or Materials relate primarily to the Programs, then possession of
such Data, Records and/or Materials will be transferred to the Buyers within a
reasonable time period after such relation is determined and in any event within
forty-five (45) days after the Closing Date, except that the Sellers may redact
any information contained in such Data or Records that does not pertain
primarily to the Programs and the Sellers may make at their own expense and
retain electronic copies or photocopies of the portions of such Data and Records
that do not pertain exclusively to the Programs. If, on the other hand, certain
Data, Records or Materials do not relate primarily to the Programs, then
possession of such Data, Records and Materials will be transferred to Coulter
(or another Seller designated by Corixa) or will be retained by the Seller in
possession of such Data, Records or Materials, as the case may be, within a
reasonable time period after such relation is determined and in any event within
forty-five (45) days after the Closing Date, except that the Buyers may redact
any information contained in such Data or Records that pertains exclusively to
the Programs, and the Buyers may make at their expense and retain electronic
copies or photocopies of the portions of such documents that pertain primarily
to the Programs.


                                      -24-
<PAGE>


            (b) If either Party requires access for legal or regulatory purposes
to original copies of any Data or Records that have been transferred to or
retained by the other Party, the Party in possession of such originals will make
such originals available to the other Party on a temporary basis on such Party's
reasonable request. The Party receiving such originals will return them to the
Party that provided them as promptly as practicable and in any event promptly
after they are no longer need for such legal or regulatory purpose.

        6.4 CONFIDENTIALITY. The Parties have previously executed a mutual
non-disclosure agreement dated September 21, 2000, as amended on March 29, 2002
(the "Confidentiality Agreement"), which shall continue in full force and effect
in accordance with its terms. In addition, the Parties agree that the terms and
conditions of the transactions contemplated by this Agreement, the information
exchanged in connection with the execution hereof and the consummation of the
transactions contemplated hereby shall be subject to the same standard of
confidentiality as set forth in the Confidentiality Agreement.

        6.5 PUBLIC DISCLOSURE. No Party shall issue any press release or
otherwise make any public (or nonconfidential) disclosure (whether or not in
response to an inquiry) regarding the terms of this Agreement and the
transactions contemplated hereby without the prior approval of the other Party
(which approval shall not be unreasonably withheld), except as may be required
by Law or by obligations pursuant to the listing requirements of Nasdaq. If
either Party is required to make any such public disclosure, the Party required
to make the disclosure shall use its reasonable efforts to give the other Party
prior notice and an opportunity to review the disclosure prior to the public
release of information.

        6.6 TAXES. The Buyers will bear and pay, and will reimburse the Sellers
for, any sales taxes, use taxes, transfer taxes, documentary charges, recording
fees, filing fees or similar taxes, charges, fees or expenses ("Transfer Taxes")
that may become payable in connection with the sale of the Assets to the Buyers
and the assumption by the Buyers of the Assumed Liabilities. The Parties shall
cooperate with each other and use commercially reasonable efforts to minimize
the Transfer Taxes. Without limiting the foregoing, all software included in the
Assets shall, unless otherwise agreed by the Parties, be delivered to the Buyers
by remote telecommunications, or installed by the Sellers onto a computer owned
by a Buyer, in compliance with California Sales and Use Tax Regulations Section
1502.

        6.7 SECURITIES LAW MATTERS.

               (a) Medarex shall take such steps as may be necessary to comply
with the securities and blue sky Laws of all jurisdictions that are applicable
to the issuance of the Medarex Stock constituting the Guaranteed Component and,
if applicable, the Contingent Component. Corixa shall use its reasonable best
efforts to assist Medarex as may be necessary to comply with the securities and
blue sky Laws of all jurisdictions that are applicable in connection with the
issuance of the Medarex Stock constituting the Guaranteed Component and, if
applicable, the Contingent Component.

        (b) Medarex will file a Prospectus Supplement with the SEC pursuant to
Rule 424(b) under the 1933 Act not later than the SEC's close of business on the
second business day following the Closing Date or, if applicable on the second
business day following the


                                      -25-
<PAGE>


issuance of the Medarex Stock constituting the Contingent Component or, if
applicable in each such case, such earlier time as may be required by Rule
424(b).

        6.8 FORMATION OF MEDAREX BELGIUM. As soon as commercially reasonable and
no later than forty-five (45) days after the Closing Date, Medarex shall take
all reasonable action required under Belgian Law to complete the formation of
Medarex Belgium and to ensure that (a) Medarex Belgium is duly organized,
validly existing and in good standing under Belgian Law; (b) Medarex Belgium has
full corporate power and authority to execute and deliver this Agreement and
each of the Operative Documents to which it is a party, to perform its
obligations hereunder and thereunder and to consummate the transactions
contemplated hereby and thereby, (c) the execution and delivery by Medarex
Belgium of this Agreement and each of the Operative Documents to which Medarex
Belgium is a party have been duly authorized by all necessary action of Medarex
Belgium and (d) this Agreement and each of the Operative Documents to which
Medarex Belgium is a party constitutes a valid and binding obligation of Medarex
Belgium, enforceable in accordance with its terms, except as such enforceability
may be limited by bankruptcy, insolvency, reorganization or similar Laws
affecting creditors' rights generally or by general equitable principles. To the
extent the foregoing covenant is not performed in all material respects, Medarex
hereby unconditionally guarantees the obligations of Medarex Belgium under this
Agreement and each of the Operative Documents to which Medarex Belgium is a
party.

        6.9 REMOVAL OF LIENS. As soon as commercially reasonable and no later
than ninety (90) days after the Closing Date, the Sellers shall take all action
as necessary to cause all Liens on the Equipment identified on Schedule 2.1 to
the Seller Disclosure Memorandum to be removed.

        6.10 TERMINATION OF ASSIGNED CONTRACTS. As soon as commercially
reasonable and no later than forty-five (45) days after the Closing Date, Corixa
shall deliver to the applicable Third Party notice of termination of the
Assigned Contracts designated as Assigned Contracts to be terminated after
Closing on Schedule 2.1 to the Seller Disclosure Memorandum.

7.      SCHEDULED EMPLOYEES.

        7.1 TRANSITION OF SCHEDULED EMPLOYEES. Subject to and in accordance with
the provisions of this Section 7, effective as of the Closing Date, Medarex
shall offer employment to those employees of the Sellers listed on Schedule 7.1
to the Seller Disclosure Memorandum (the "Scheduled Employees"), and such
Scheduled Employees who accept employment with Medarex after the Closing Date
(the "New Medarex Employees") shall be subject to Medarex's standard employment
practices and policies. The employment by the Sellers of each Scheduled Employee
shall terminate as of 11:59 p.m. on the Closing Date, and the at-will employment
by Medarex of the New Medarex Employees shall commence as of (i) 12:00 a.m.
midnight on the date immediately after the Closing Date, provided that such New
Medarex Employee has accepted employment with Medarex by such time or within
five (5) business days after the Closing Date or (ii) such later time as such
New Medarex Employee has accepted employment with Medarex (the "Start Time").
The terms of employment with Medarex (or Medarex's Affiliates) shall be as
mutually agreed between each New Medarex Employee and Medarex (or Medarex's
Affiliate, as the case may be), subject to the provisions of this Section 7. As
of the


                                      -26-
<PAGE>


Start Time, all New Medarex Employees will be under the exclusive supervision of
Medarex and subject to Medarex's policies and procedures.

        7.2 COMPENSATION OF NEW MEDAREX EMPLOYEES. The Buyers shall have no
obligation with respect to payments of salary, compensation, wages, health or
similar benefits, commissions, bonuses (deferred or otherwise), severance,
accrued vacation and sick leave, stock or stock options or any other sums due to
any New Medarex Employee that accrued before the Start Time (including any
payments accruing due to the transactions contemplated by this Agreement). The
Sellers will be fully responsible for all amounts owing to the New Medarex
Employees as a result of their employment prior to the Closing Date and shall
under no circumstances be responsible for any amounts payable to any New Medarex
Employee that arise at or after the Closing Date. The Sellers shall pay each New
Medarex Employee all wages owed in accordance with and to the extent applicable
under its standard employment policies and procedures, and applicable law, on
the Closing Date. Corixa shall pay each New Medarex Employee his or her accrued
but unused vacation (a "Vacation Liability") in accordance with its standard
employment policies and procedures, and applicable Law, on the Closing Date;
provided, however, that in the case of any New Medarex Employee who declines
such cash payment and elects in writing and in lieu thereof to have his or her
Vacation Liability assumed by Medarex (a "Vacation Election"), then Medarex
shall assume such Vacation Liability. No later than five (5) business days after
the Closing Date, Corixa shall reimburse Medarex in cash for the Vacation
Liability assumed by Medarex pursuant to this Section 7.2 for all New Medarex
Employees with respect to whom Corixa receives a valid Vacation Election.

        7.3 COMPENSATION AND BENEFITS OF SCHEDULED EMPLOYEES.

            (a) At the Start Time, with respect to each Scheduled Employee,
coverage for and participation by such Scheduled Employee under all of the
Sellers' compensation and Employee Benefit Plans and other programs shall
terminate (except as otherwise required by law) and, with respect to each New
Medarex Employee, coverage and participation under Medarex's compensation and
Employee Benefit Plans and other programs shall commence.

            (b) Sellers shall retain or assume responsibility for providing
health care coverage to all Scheduled Employees (or any individual who
constitutes a qualified beneficiary under Section 4980B of the Code ("COBRA")
with respect to a Scheduled Employee) who are receiving (or become entitled to
receive) continuation health coverage pursuant to an election made under COBRA
or Sections 601-608 of ERISA (such an election to be called a "COBRA election")
relating to a qualifying event occurring (i) prior to the Start Time for
Scheduled Employees and (ii) prior to, at or after the Start Time for all
employees of Sellers who are not Scheduled Employees. Medarex shall be
responsible for providing health care coverage attributable to a COBRA election
made by a New Medarex Employee (or any individual who constitutes a qualified
beneficiary under COBRA with respect to a New Medarex Employee) which relates to
a qualifying event which occurs at or after the Start Time.

            (c) Sellers shall remain solely liable for all claims under Sellers'
compensation and Employee Benefit Plans that are incurred by (i) all employees
of Sellers who are not Scheduled Employees, including New Medarex Employees, and
their beneficiaries and covered dependents and (ii) Scheduled Employees and
their beneficiaries and covered


                                      -27-
<PAGE>


dependents prior to the Start Time. Medarex shall be solely liable for all
claims under Medarex's compensation and Employee Benefit Plans that are incurred
by New Medarex Employees and their beneficiaries and covered dependents at or
after the Start Time. For these purposes, a claim shall be deemed to have been
incurred at the time when the events giving rise to the claim occurred.

            (d) Sellers shall remain responsible and liable for workers'
compensation claims relating to occupational illnesses resulting from exposure
occurring prior to the Start Time and injuries that are incurred (i) prior to
the Start Time with respect to the New Medarex Employees and (ii) prior to, at
or after the Start Time with respect to all employees of Sellers who are not
Scheduled Employees.

        7.4 NO RIGHT TO CONTINUED EMPLOYMENT OR BENEFITS. No provision in this
Agreement shall create any Third Party beneficiary or other right in any Person
(including any beneficiary or dependent thereof) for any reason, including,
without limitation, in respect of continued, resumed or new employment with the
Sellers or the Buyers (or any Affiliate of the Sellers or the Buyers) or in
respect of any benefits that may be provided, directly or indirectly, under any
plan or arrangement maintained by the Sellers, the Buyers or any Affiliate of
the Sellers or the Buyers. Except as otherwise expressly provided in this
Agreement, no Buyer is under any obligation to hire any employee of the Sellers,
provide any employee with any particular benefits, or make any payments or
provide any benefits to those employees of the Sellers whom a Buyer chooses not
to employ.

        7.5 CERTAIN PAYMENTS. In the event that, prior to the date that is nine
(9) months after the Closing Date, a Buyer shall hire any employees of the
Sellers listed on Schedule 7.5 to the Seller Disclosure Memorandum (the
"Identified Employees"), Medarex shall pay to Corixa a fee with respect to each
such Identified Employee (the "Hiring Fee") as follows: (i) if the Identified
Employee's employment was terminated by any Seller prior to such hiring by such
Buyer, the fee shall be equal to the lesser of [*] percent ([*]%) of such
Identified Employee's severance payment made by such Seller and [*] percent
([*]%) of such Identified Employee's annual salary; (ii) if such Identified
Employee voluntarily terminates his or her own employment with any Seller, the
fee shall be equal to [*] percent ([*]%) of such Identified Employee's annual
salary; and (iii) if such Identified Employee is employed in good faith by a
Third Party after cessation of his or her employment with such Seller and prior
to commencement of his or her employment with such Buyer, there shall be no fee.
Payment of the Hiring Fee shall be made no later than five (5) business days
after the commencement of such Identified Employee's employment with such Buyer
by check or wire transfer of immediately available funds to such bank account of
Corixa as Corixa may designate.

        7.6 WAIVER OF TAIL PROVISION. Each of the Sellers hereby waives the Tail
Provision of its Proprietary Rights and Inventions Agreements with each
Scheduled Employee who accepts employment with Medarex with respect to and only
with respect to Inventions related to the Programs. All other terms of such
Proprietary Rights and Inventions Agreements shall continue in full force and
effect.

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        7.7 OWNERSHIP OF SCHEDULED EMPLOYEE INVENTIONS.

            (a) The Sellers acknowledge and agree that Medarex shall own all
right, title and interest in and to:

                (i) all Intellectual Property Rights relating to Inventions that
are made, first conceived and first reduced to practice by a New Medarex
Employee; and

                (ii) all Intellectual Property Rights relating to Inventions
that (y) relate to the expression, manufacture, modification, formulation,
production, lead generation and lead optimization of antibodies and (z) are made
or first reduced to practice by New Medarex Employee; provided, however, that
Seller shall retain all right, title and interest in and to any Intellectual
Property Rights that are embodied in any descriptive writing, whether in hard
copy or electronic form, prior to the Start Time (such Intellectual Property
Rights, "Seller IP"); provided further that to the extent such Seller IP is
included in the Transferred Intellectual Property Rights, it shall be
transferred and assigned to Buyers pursuant to the terms of this Agreement.

            (b) Notwithstanding anything herein to the contrary, the Buyers
hereby waive, and agree not to sue any of Corixa or its Affiliates or licensees,
on a perpetual basis, with respect to any claim of misappropriation of trade
secrets owned or controlled by any of Medarex or its Affiliates or licensees
where such claim is based on any use, control or disclosure of
Concurrently-Known Information by any of Corixa or its Affiliates or Scheduled
Employees.

        7.8 OWNERSHIP OF INTELLECTUAL PROPERTY DEVELOPED BY SCHEDULED EMPLOYEES
WHO DO NOT JOIN MEDAREX. The Sellers acknowledge and agree that Medarex shall
own all right, title and interest in and to all Intellectual Property Rights
(only to the extent such Intellectual Property Rights are owned by Corixa under
the terms of a Proprietary Rights and Inventions Agreement or otherwise)
relating to Inventions (only to the extent such Inventions are related to the
Programs) and that are made, first conceived or first reduced to practice during
the one-year period immediately following the Closing Date by (a) a Scheduled
Employee who does not accept employment at Medarex or (b) any of the individuals
set forth on Schedule 7.8 to the Seller Disclosure Memorandum; provided that in
the event of a dispute between Corixa and any such individual regarding the
ownership of any such Intellectual Property Rights or such Inventions, Medarex
shall have the right to take any actions, on Corixa's behalf, that are deemed
appropriate by Medarex (in its sole discretion) to resolve any such dispute,
including without limitation litigation of such dispute; and provided further
that Corixa shall reasonably cooperate with Medarex with respect to such
actions, with any and all costs, including without limitation, fully-burdened
FTE costs and out-of-pocket costs, of Corixa incurred in connection with such
cooperation, including, without limitation in connection with any litigation, to
be reimbursed by Medarex.

        7.9 NEW MEDAREX EMPLOYEE RECORDS. After the Closing, the Sellers shall
transfer to any New Medarex Employee who so requests in writing, his or her
personnel file.


                                      -29-
<PAGE>


8.      DELIVERIES.

        8.1 DELIVERIES BY SELLERS. The Sellers shall deliver the following
documents, agreements and supporting papers to the Buyers at the Closing, and
the delivery of each shall be a condition to the Buyers' performance of their
respective obligations at the Closing:

            (a) the Bill of Sale, duly executed by the Sellers;

            (b) counterparts of the Assignment and Assumption Agreement and the
Belgian Assignment and Assumption Agreement, duly executed by the Sellers;

            (c) the Assignment of Patents, duly executed by the Sellers,
covering the Transferred Patents;

            (d) a counterpart of the Facilities Services and Lease Agreement,
duly executed by the Sellers;

            (e) the Required Consents, in form and substance reasonably
satisfactory to Medarex;

            (f) the opinion of the Sellers' counsel, Orrick, Herrington &
Sutcliffe LLP, dated the date hereof, substantially in the form attached as
Exhibit D;

            (g) a certificate of the Secretary of Corixa and Coulter, and of a
director of Corixa Belgium, in form and substance reasonably satisfactory to
Medarex, as to the authenticity and effectiveness of the actions of the board of
directors of such Seller authorizing the transactions contemplated by this
Agreement and the Operative Documents;

            (h) a certificate of the Secretary of State of the state of Delaware
to the effect that each of Corixa and Coulter is a corporation duly organized,
validly existing and in good standing under the laws of the state of Delaware;

            (i) a counterpart of the license agreement between Medarex and
Corixa with respect to the UPT Technology, substantially in the form attached as
Exhibit E (the "UPT License Agreement"), duly executed by Corixa;

            (j) a counterpart of the license agreement between Corixa and
Medarex with respect to the leader peptide patent, substantially in the form
attached as Exhibit L (the "Leader Peptide Patent License Agreement"), duly
executed by Corixa;

            (k) a counterpart of the license agreement between Medarex and
Corixa with respect to [*] antigen and monoclonal antibodies generated thereto,
substantially in the form attached as Exhibit F (the "[*] Agreement"), duly
executed by Corixa;

            (l) a counterpart of the sublease between Medarex and Coulter with
respect to the first and second floors of Coulter's facility located at 650
Gateway Boulevard, South San

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                                      -30-
<PAGE>


Francisco, California, substantially in the form attached as Exhibit G (the
"Sublease"), duly executed by Coulter; and

            (m) evidence reasonably satisfactory to Medarex of the release by
any Person who held any Lien on the Assets of all Liens on the Assets (except as
otherwise provided on Schedule 4.4 to the Seller Disclosure Memorandum).

        8.2 DELIVERIES BY THE BUYERS. The Buyers shall deliver the following
documents, agreements and supporting papers to Sellers at the Closing, and the
delivery of each shall be condition to Sellers' performance of their respective
obligations at the Closing:

            (a) counterparts of the Assignment and Assumption Agreement and the
Belgian Assignment and Assumption Agreement, duly executed by the Buyers;

            (b) the opinion of the Buyers' counsel, Cooley Godward LLP, dated
the date hereof, substantially in the form attached as Exhibit H;

            (c) the opinion of the Buyers' counsel, Satterlee Stephens Burke &
Burke LLP, dated the date hereof, substantially in the form attached as Exhibit
I;

            (d) a certificate of the Secretary of Medarex, in form and substance
reasonably satisfactory to the Sellers, as to the authenticity and effectiveness
of the actions of the board of directors of Medarex authorizing the transactions
contemplated by this Agreement and the Operative Documents;

            (e) a certificate of the Secretary of State of the state of New
Jersey to the effect that Medarex is a corporation duly organized, validly
existing and in good standing under the laws of the state of New Jersey;

            (f) a counterpart of the Facilities Services and Lease Agreement,
duly executed by Medarex;

            (g) a counterpart of the UPT License Agreement, duly executed by
Medarex;

            (h) a counterpart of the Leader Peptide Patent License Agreement,
duly executed by Medarex;

            (i) a counterpart of the Sublease, duly executed by Medarex;

            (j) a counterpart of the [*] Agreement, duly executed by Medarex;

            (k) the Prospectus Supplement; and

            (l) in the event Medarex elects to make the first Monthly Payment in
shares of Medarex Stock, the Irrevocable Instruction Letter.

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<PAGE>


9.      INDEMNIFICATION.

        9.1 SURVIVAL. Subject to Section 9.5(b), all representations and
warranties contained in this Agreement or in the other Operative Documents or in
any certificate delivered pursuant hereto or thereto shall survive until 5:00
p.m., Pacific time, on the first anniversary of the Closing (the "Survival
Period") and shall not be deemed waived or otherwise affected by any
investigation made or any knowledge acquired with respect thereto. For purposes
of this Agreement, each statement or other item of information set forth in the
Seller Disclosure Memorandum shall be deemed to be a representation and warranty
made by the Sellers in this Agreement. The covenants and agreements contained in
this Agreement shall survive and continue until all obligations with respect
thereto shall have been performed or satisfied or shall have been terminated in
accordance with their terms.

        9.2 INDEMNIFICATION BY SELLERS. From and after the Closing, each Seller
jointly and severally shall indemnify, defend and hold harmless each Buyer and
its Affiliates, and their respective officers, directors, stockholders,
employees, agents and controlling Persons (the "Buyer Indemnified Parties"),
from and against and shall compensate and reimburse any such party for any and
all liability, damage, deficiency, loss, judgments, assessments, cost and
expense, including reasonable attorneys' fees, expert witness fees, and other
fees and costs of investigating and defending against lawsuits, complaints,
actions or other pending or threatened litigation (and including any appeal
thereof) ("Losses"), to the extent arising from or attributable to:

            (a) Any inaccuracy in the representations and warranties made by a
Seller in this Agreement;

            (b) Any failure of any Seller to perform or observe any covenant or
agreement to be performed or observed by such Seller pursuant to this Agreement;

            (c) The ownership, use or operation of the Assets by a Seller on or
prior to the Closing.

            (d) The Excluded Liabilities;

            (e) Any amounts owing to the Scheduled Employees as a result of
their employment at or prior to the Closing;

            (f) Investigations or actions by Governmental Entities involving the
Assets that relate to actions of any Seller or its agents that occurred on or
prior to the Closing or conditions or events that existed at or prior to the
Closing;

            (g) The presence of any Material of Environmental Concern at the
Subleased Premises, at any time prior to the Closing (except as provided in
Section 4.12);

            (h) The generation, manufacture, production, transportation,
importation, use, treatment, refinement, processing, handling, storage,
discharge, release or disposal of any Material of Environmental Concern (whether
lawfully or unlawfully) by or on behalf of the Sellers at the Subleased Premises
at any time prior to the Closing;


                                      -32-
<PAGE>


            (i) Any Proceeding commenced by any Buyer Indemnified Party for the
purpose of enforcing any of its rights under this Section 9 to the extent such
Buyer Indemnified Party is the prevailing party in such Proceeding;

            (j) Any failure to comply with any bulk transfer law or similar Law
in connection with any of the transactions contemplated by this Agreement; and

            (k) Any notices, payments, benefits, fines, penalties, backpay and
damages required under the Worker Adjustment and Retraining Notification Act
(the "WARN Act") and other applicable Laws relating to reductions in force or
termination of employment arising out of or as a result of the transactions
contemplated by this Agreement, except to the extent any Losses arising under
the matters described in this Section 9.2(k) result from a breach by a Buyer of
its covenants under Section 7.

        9.3 INDEMNIFICATION BY THE BUYERS. The Buyers shall indemnify, defend
and hold harmless each Seller and its Affiliates, and their respective officers,
directors, stockholders, employees, agents and controlling Persons (the "Seller
Indemnified Parties" and, together with the Buyer Indemnified Parties, the
"Indemnified Parties") from and against and shall reimburse any such party for
any and all Losses to the extent arising from or attributable to:

            (a) Any inaccuracy in the representations and warranties made by a
Buyer in this Agreement;

            (b) Any failure of a Buyer to perform or observe any covenant or
agreement to be performed or observed by such Buyer pursuant to this Agreement;

            (c) The ownership, use or operation of any of the Assets after the
Closing;

            (d) The Assumed Liabilities;

            (e) Any amount owing to Scheduled Employees as a result of their
employment after the Closing;

            (f) Any investigations or actions by Governmental Entities involving
the Assets that relate to actions of a Buyer or its agents that occurred after
the Closing or conditions or events that occurred or came into existence after
the Closing;

            (g) The presence of any Material of Environmental Concern at the
Subleased Premises at any time after the Closing, except to the extent such
Material of Environmental Concern was present at the Subleased Premises at or at
any time before the Closing;

            (h) The generation, manufacture, production, transportation,
importation, use, treatment, refinement, processing, handling, storage,
discharge, release or disposal of any Material of Environmental Concern (whether
lawfully or unlawfully) by or on behalf of Medarex at the Subleased Premises at
any time after the Closing; and


                                      -33-
<PAGE>


            (i) Any Proceeding commenced by any Seller Indemnified Party for the
purpose of enforcing any of its rights under this Section 9 to the extent such
Seller Indemnified Party is the prevailing party in such Proceeding.

        9.4 INDEMNIFICATION PROCEDURES. Any Indemnified Party seeking
indemnification hereunder shall give written notice (a "Claim Notice") of any
claim for indemnification under this Section 9 (an "Indemnification Claim") to
the other Party (the "Indemnifying Party") as promptly as practicable after the
discovery of facts upon which the Indemnified Party intends to base an
Indemnification Claim or, if such indemnification claim relates to the assertion
against the Indemnified Party of any claim by a Third Party (a "Third-Party
Claim"), promptly after the receipt by the Indemnified Party of notice of the
Third-Party Claim. The written notice of an Indemnification Claim shall describe
the facts and circumstances on which the asserted Indemnification Claim is
based, the amount thereof if then ascertainable (or, if not then ascertainable,
the estimated maximum amount thereof) and the provisions of this Agreement on
which the Indemnification Claim is based. After giving such notice of a
Third-Party Claim, the Indemnified Party shall permit the Indemnifying Party,
subject to the rights of or duties to any insurer or other Third Party having
potential liability therefor, to assume the defense of any such claim or any
litigation resulting from such claim, and, upon such assumption, shall cooperate
fully with the Indemnifying Party in the conduct of such defense. If the
Indemnifying Party has notified the Indemnified Party of the Indemnifying
Party's election to defend any such action within fifteen (15) days after notice
thereof has been given to the Indemnifying Party, the provisions of Section
9.4(a) shall govern. If the Indemnifying Party elects not to assume defense of a
Third-Party Claim, or fails to provide notification of its election within the
fifteen-day period, the Indemnifying Party shall be deemed to have waived its
right to defend such action and the provisions of Section 9.4(b) shall govern.

            (a) If the Indemnifying Party assumes the defense of any Third-Party
Claim or litigation resulting therefrom, the obligations of the Indemnifying
Party as to such claim shall be limited to taking all steps necessary in the
defense or settlement of such claim or litigation resulting therefrom. The
Indemnified Party may participate, at its expense, in the defense of such
Third-Party Claim or litigation, provided that the Indemnifying Party shall
direct and control the defense of such claim or litigation. The Indemnifying
Party shall not, in the defense of such Third-Party Claim or any litigation
resulting therefrom, consent to entry of any judgment that would adversely
affect the Indemnified Party, except with the written consent of the Indemnified
Party, or enter into any settlement that would adversely affect the Indemnified
Party, except with the written consent of the Indemnified Party, which judgment
or settlement does not include as an unconditional term thereof the delivery by
the claimant or the plaintiff to the Indemnified Party of a release from all
liability in respect of such Third-Party Claim or litigation. In addition, all
awards and costs payable by a Third Party to the Indemnified Party or the
Indemnifying Party shall belong to the Indemnifying Party. Any settlement by the
Indemnifying Party shall not, without the prior written consent of the
Indemnified Party, impose any obligation on the Indemnified Party or adversely
affect the Indemnified Party's rights hereunder.

            (b) If the Indemnifying Party shall not assume the defense of a
Third-Party Claim or litigation resulting therefrom, the Indemnified Party may
defend against such claim or litigation in such manner as it may deem
appropriate, and the Indemnifying Party shall promptly


                                      -34-
<PAGE>


reimburse the Indemnified Party for the amount of all expenses, legal or
otherwise, and other amounts for which the Indemnifying Party is obligated
hereunder, incurred by the Indemnified Party in connection with the defense
against or settlement of such Third-Party Claim or litigation. If no settlement
of such Third-Party Claim or litigation is made, the Indemnifying Party shall
promptly reimburse the Indemnified Party for the amount of any final and
nonappealable judgment rendered with respect to such Third-Party Claim or in
such litigation and of all expenses, legal or otherwise, and other amounts for
which the Indemnifying Party is obligated hereunder, incurred by the Indemnified
Party in the defense against such claim or litigation.

        9.5 LIMITATIONS ON INDEMNIFICATION.

            (a) The Indemnified Parties shall not be entitled to receive any
indemnification payment with respect to any Indemnification Claim under Sections
9.2 (a) and (b) and Section 9.3(a) and (b), as applicable, until the aggregate
Losses for which such Indemnified Parties would be otherwise entitled to receive
indemnification exceed [*] Dollars ($[*]) (the "Threshold"); provided, however,
that once the aggregate Losses exceed the Threshold, such Indemnified Parties
shall be entitled to indemnification for the aggregate amount of all Losses
without regard to the Threshold; provided, further, that the Threshold shall not
apply to any Indemnification Claim arising under Section 9.2(b) as a result of a
breach of the covenant in Section 6.9.

            (b) The indemnification provided in this Section 9 shall be the sole
and exclusive remedy after the Closing for damages available to the Parties for
breach of any of the representations or warranties or covenants contained
herein; provided, however, this exclusive remedy for damages does not preclude a
Party from bringing an action for (A) fraud (including violations of the
antifraud provisions of the Securities Act or Exchange Act in connection with
the issuance of the Medarex Stock) or (B) specific performance or other
equitable remedy to require a Party to perform its obligations under this
Agreement or the Operative Documents.

            (c) An Indemnifying Party shall not be obligated to defend and hold
harmless an Indemnified Party, or otherwise be liable to such Party, with
respect to any claims made by the Indemnified Party after the expiration of the
Survival Period or other applicable time limitation described in Section 9.1,
except that indemnity may be sought after the expiration of the Survival Period
or other applicable time limitation for any Indemnification Claim described in a
Claim Notice that is delivered to the Indemnifying Party prior to the expiration
of the Survival Period or such other time limitation applicable to such
Indemnification Claim.

            (d) Notwithstanding anything to the contrary herein, except for
Losses based on fraud (including violations of the antifraud provisions of the
Securities Act or Exchange Act in connection with the issuance of the Medarex
Stock), the aggregate Liability of any Indemnifying Party under this Section 9
for Losses arising from or attributable to (i) any inaccuracy in the
representations and warranties made by such Indemnifying Party in this Agreement
or any of the Operative Documents and (ii) any failure of such Indemnifying
Party to perform or observe any covenant or agreement to be performed or
observed by such

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                                      -35-
<PAGE>


Indemnifying Party pursuant to this Agreement or any of the Operative Documents
shall not exceed the dollar amount of the Purchase Price, including the net
amount of the Contingent Component, as finally determined in accordance with
Section 2.4(b). The maximum aggregate Liability provided by the preceding
sentence shall not be applicable to any other matter set forth in Sections
9.2(c)-(k) or Sections 9.3(c)-(i).

            (e) The amount of an Indemnifying Party's liability under this
Agreement shall be reduced by ninety percent (90%) of the amount of any
applicable insurance proceeds actually received by the Indemnified Party.

            (f) Notwithstanding anything contained in this Agreement to the
contrary, no Party shall be liable to the other Party for special, punitive or
exemplary damages arising out of this Agreement; provided, however, that the
foregoing shall not be construed to preclude recover by the Indemnified Party in
respect of Losses directly incurred from Third-Party Claims.

            (g) No Buyer Indemnified Party shall have any right to offset,
deduct, counterclaim or otherwise withhold any amount from the Guaranteed
Component or the Contingent Component due to Seller with respect to any pending
or unresolved claim under this Section 9; provided, however, that a Buyer
Indemnified Party shall have the right to offset, deduct, counterclaim and
otherwise withhold any amount from the Guaranteed Component or Contingent
Component due to Seller with respect to any Resolved Claim under this Section 9
that has not been paid in full.

10.     MISCELLANEOUS.

        10.1 EXPENSES. Subject to the provisions of Section 9, regardless of
whether the transactions contemplated by this Agreement are consummated, each
Party will pay its own fees and expenses incident to the negotiation,
preparation and execution of this Agreement and the other Operative Documents
and the consummation of the transactions contemplated hereby and thereby
(including legal fees and accounting expenses).

        10.2 AMENDMENTS AND WAIVERS. Any term of this Agreement may be amended,
modified or waived only with the written consent of the Parties or their
respective successors and assigns. Any amendment or waiver effected in
accordance with this Section 10.2 shall be binding on the Parties and their
respective successors and assigns.

        10.3 SUCCESSORS AND ASSIGNS. Neither of the Parties may assign any of
its rights or obligations hereunder without the prior written consent of the
other Party. This Agreement shall be binding on and inure to the benefit of the
Parties and their respective successors and assigns. Except for the provisions
of Section 9 hereof, none of the provisions of this Agreement is intended to
provide any rights or remedies to any Third Party. Without limiting the
generality of the foregoing, (a) no employee of the Sellers shall have any
rights under this Agreement or any of the Operative Documents and (b) no
creditor of the Sellers shall have any rights under this Agreement or the
Operative Documents.

        10.4 GOVERNING LAW. This Agreement and all acts and transactions
pursuant hereto and the rights and obligations of the Parties shall be governed,
construed and interpreted in


                                      -36-
<PAGE>


accordance with the Laws of the state of California, without giving effect to
principles of conflict of Laws.

        10.5 COUNTERPARTS. This Agreement may be executed in two or more
counterparts, each of which shall be deemed an original and all of which
together shall constitute one instrument.

        10.6 TITLES AND SUBTITLES. The titles and subtitles used in this
Agreement are used for convenience only and are not to be considered in
construing or interpreting this Agreement.

        10.7 NOTICE. Any notice required or permitted by this Agreement shall be
in writing and shall be deemed sufficient upon receipt, when delivered
personally or by courier, overnight delivery service or confirmed facsimile, or
forty-eight (48) hours after being deposited in the regular mail as certified or
registered mail (airmail if sent internationally) with postage prepaid, if such
notice is addressed to the Party to be notified at such Party's address or
facsimile number as set forth below, or as subsequently modified by written
notice:

        (a)    if to the Sellers, to:

               Corixa Corporation
               Coulter Corporation
               Corixa Belgium, S.A.
               1124 Columbia Street, Suite 200
               Seattle, Washington 98104
               Attention:  General Counsel
               Facsimile No.:  (206) 754-5994
               Telephone No.:  (206) 754-5711

               with a copy to:

               Orrick, Herrington & Sutcliffe LLP
               719 Second Avenue, Suite 900
               Seattle, Washington 98104
               Attention:  Stephen M. Graham
                           Alan C. Smith
               Facsimile No.:  (206) 839-4301
               Telephone No.:  (206) 839-4300

        (b)    if to the Buyers, to:

               Medarex, Inc.
               Medarex Belgium, S.A.
               707 State Road, #206
               Princeton, New Jersey  08540
               Attention:  General Counsel
               Facsimile No.:  (609) 430-2850
               Telephone No.:  (609) 430-2880


                                      -37-
<PAGE>


               with a copy to:

               Cooley Godward LLP
               5 Palo Alto Square
               3000 El Camino Real
               Palo Alto, California  94306-2155
               Attention:  Suzanne S. Hooper
               Facsimile No.:  (650) 849-7400
               Telephone No.: (650) 843-5000

        10.8 SEVERABILITY. If one or more provisions of this Agreement are held
to be unenforceable under applicable law, the Parties agree to renegotiate such
provision in good faith in order to maintain the economic position enjoyed by
each Party as close as possible to that under the provision rendered
unenforceable. In the event that the Parties cannot reach a mutually agreeable
and enforceable replacement for such provision, then (a) such provision shall be
excluded from this Agreement, (b) the balance of this Agreement shall be
interpreted as if such provision were so excluded and (c) the balance of this
Agreement shall be enforceable in accordance with its terms.

        10.9 CUMULATIVE REMEDIES. All rights and remedies available to either
Party for breach of this Agreement are cumulative (and not alternative) and may
be exercised concurrently or separately, and the exercise of any one remedy will
not be deemed an election of such remedy to the exclusion of any other remedy.
Each Party (the "Plaintiff Party") agrees that: (a) in the event of any breach
or threatened breach by the other Party of any covenant, obligation or other
provision set forth in this Agreement, the Plaintiff Party shall be entitled (in
addition to any other remedy that may be available to it) to (i) a decree or
order of specific performance or mandamus to enforce the observance and
performance of such covenant, obligation or other provision, and (ii) an
injunction restraining such breach or threatened breach; and (b) neither the
Plaintiff Party nor any other Indemnified Party shall be required to provide any
bond or other security in connection with any such decree, order or injunction
or in connection with any related action or Proceeding.

        10.10 FORCE MAJEURE. Nonperformance by either Party under this
Agreement, except for Medarex's performance of its payment obligations, which
shall in no event be excused, will be excused while and to the extent that
performance is rendered impossible by strike, fire, flood, earthquake,
governmental action, or any other reason where failure to perform is beyond the
reasonable control of the nonperforming Party.

        10.11 CONSTRUCTION OF AGREEMENT. Each Party has cooperated in the
drafting and preparation of this Agreement and no principles of construction
will be applied against either Party on the basis that such Party drafted this
Agreement.

        10.12 NO IMPLIED WAIVER. No right under this Agreement or breach hereof
may be waived except in writing signed by the Parties. Neither the failure of a
Party to require performance of any provision of this Agreement nor the delay in
enforcing any right hereunder will be construed or act as a waiver of such
Party's rights to insist on performance of such provision or any other provision
or enforce any such right at some other time.


                                      -38-
<PAGE>


        10.13 ENTIRE AGREEMENT. This Agreement, the Confidentiality Agreement
and the Operative Documents constitute the entire agreement between such Parties
with respect to the subject matter hereof and thereof and supersede all prior
agreements and understandings, both written and oral, between the Parties with
respect to the subject matter hereof and thereof.

        10.14 WAIVER OF JURY TRIAL. EACH PARTY HEREBY IRREVOCABLY WAIVES ALL
RIGHT TO TRIAL BY JURY IN ANY ACTION, PROCEEDING OR COUNTERCLAIM (WHETHER BASED
ON CONTRACT, TORT OR OTHERWISE) ARISING OUT OF OR RELATING TO THIS AGREEMENT,
THE TRANSACTIONS CONTEMPLATED HEREBY OR THE ACTIONS OF SUCH PARTIES IN THE
NEGOTIATION, ADMINISTRATION, PERFORMANCE AND ENFORCEMENT HEREOF.

                            [Signature page follows.]


                                      -39-
<PAGE>


        IN WITNESS WHEREOF, this Asset Purchase Agreement has been duly executed
and delivered by the duly authorized officers of each Seller and each Buyer as
of the date first above written.

                                    THE BUYERS:

                                    MEDAREX, INC.


                                    By:  /s/ W. Bradford Middlekauff
                                         --------------------------------------
                                         Name: W. Bradford Middlekauff
                                              ---------------------------------
                                         Title: Senior Vice President and
                                               --------------------------------
                                                General Counsel
                                               --------------------------------


                                    For MEDAREX BELGIUM, S.A., a company in the
                                    course of being incorporated as defined by
                                    Article 60 of the Belgian Companies Code


                                    By:  /s/ W. Bradford Middlekauff
                                         --------------------------------------
                                         Name: W. Bradford Middlekauff
                                              ---------------------------------
                                         Title: Senior Vice President and
                                               --------------------------------
                                                General Counsel of Medarex, Inc.
                                               --------------------------------



                                    THE SELLERS:

                                    CORIXA CORPORATION


                                    By:  /s/ Steven Gillis, Ph.D.
                                         --------------------------------------
                                         Name: Steven Gillis, Ph.D.
                                              ---------------------------------
                                         Title: Chairman of the Board and CEO
                                               --------------------------------


<PAGE>


                                     COULTER PHARMACEUTICAL, INC.


                                     By:  /s/ Steven Gillis, Ph.D.
                                          --------------------------------------
                                          Name: Steven Gillis, Ph.D.
                                               ---------------------------------
                                          Title: President
                                                --------------------------------


                                     CORIXA BELGIUM, S.A.


                                     By:  /s/ Steven Gillis, Ph.D.
                                          --------------------------------------
                                          Name: Steven Gillis, Ph.D.
                                               ---------------------------------
                                          Title: Director
                                                --------------------------------

                                     By:  /s/ Michelle Burris
                                          --------------------------------------
                                          Name: Michelle Burris
                                               ---------------------------------
                                          Title: Director
                                                --------------------------------