<PAGE>

                                                                  EXHIBIT 10.1

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                       COLLABORATION AND LICENSE AGREEMENT

                                 BY AND BETWEEN

                        MILLENNIUM PHARMACEUTICALS, INC.

                                       AND

                          AVENTIS PHARMACEUTICALS INC.


<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                                TABLE OF CONTENTS

<TABLE>

<CAPTION>

                                                                                                             PAGE

<S>     <C>       <C>                                                                                          <C>
ARTICLE 1         DEFINITIONS....................................................................................1
         1.1      "Active".......................................................................................1
         1.2      "Affiliate"....................................................................................1
         1.3      "Annual Research Plan".........................................................................2
         1.4      "Antibody".....................................................................................2
         1.5      "Business Day".................................................................................2
         1.6      "Change of Control"............................................................................2
         1.7      "Commercialization"or "Commercialize"..........................................................2
         1.8      "Confidential Information".....................................................................2
         1.9      "Contract Year"................................................................................3
         1.10     "Control"or "Controlled".......................................................................3
         1.11     "Covering", "Cover", or "Covered"..............................................................3
         1.12     "Development"or "Develop"......................................................................4
         1.13     "Diagnostic"...................................................................................4
         1.14     "Dropped EDC Compound".........................................................................4
         1.15     "Dropped Target"...............................................................................4
         1.16     "Druggable Target".............................................................................4
         1.17     "Early Development Candidate Status"or "EDC Status"............................................4
         1.18     "EDC Compound".................................................................................4
         1.19     "Effective Date"...............................................................................5
         1.20     "Executive Officers"...........................................................................5
         1.21     "[**] Property"................................................................................5
         1.22     "FDA"..........................................................................................5
         1.23     "First Commercial Sale"........................................................................5
         1.24     "FTE"..........................................................................................5
         1.25     "Gene Therapy".................................................................................5
         1.26     "HPB"..........................................................................................5
         1.27     "IND"..........................................................................................6
         1.28     "Inflammation Field"...........................................................................6
         1.29     "Investment Agreement".........................................................................6
         1.30     "Joint Commercialization Project Team".........................................................6
         1.31     "Joint Development Compound"...................................................................6
         1.32     "Joint Development Product"or "JD Product".....................................................6
         1.33     "Joint Development Project Team"...............................................................6
         1.34     "Joint Steering Committee".....................................................................6
         1.35     "Laws".........................................................................................6
         1.36     "Lead Compound"................................................................................6
         1.37     "Lead Compound Family".........................................................................7
         1.38     "NDA"..........................................................................................7

</TABLE>


                                      -i-

<PAGE>


<TABLE>

<CAPTION>

<S>      <C>                                                                                                    <C>
         1.39     "North America"or "NA".........................................................................7
         1.40     "Party"or "Parties"............................................................................7
         1.41     "Patent Rights"................................................................................7
         1.42     "Phase I Study"................................................................................7
         1.43     "Phase IIA Study"..............................................................................7
         1.44     "Phase IIB Study"..............................................................................7
         1.45     "Phase IIIA Study".............................................................................7
         1.46     "Phase IIIB Study".............................................................................8
         1.47     "Phase IV Study"...............................................................................8
         1.48     "Pre-EDC Research Evaluation"..................................................................8
         1.49     "Program Compound".............................................................................8
         1.50     "Program Compound Family"......................................................................8
         1.51     "Program Intellectual Property"................................................................8
         1.52     "Program Material".............................................................................8
         1.53     "Program Patent Rights"........................................................................9
         1.54     "Program Target"...............................................................................9
         1.55     "Program Technology"...........................................................................9
         1.56     "Regulatory Approval"..........................................................................9
         1.57     "Research Program".............................................................................9
         1.58     "Research Program Chemistry Intellectual Property".............................................9
         1.59     "ROW".........................................................................................10
         1.60     "ROW Major Market Countries"..................................................................10
         1.61     "Royalty-Bearing Product".....................................................................10
         1.62     "Royalty-Paying Party"........................................................................10
         1.63     "Scientifically-Qualified Target"or "SQT".....................................................10
         1.64     "Significant Pharmaceutical Enterprise".......................................................10
         1.65     "Single-Party Research Target"................................................................10
         1.66     "Single-Party Target Product".................................................................11
         1.67     "Small Molecule"..............................................................................11
         1.68     "Technology Development Agreement"............................................................11
         1.69     "Technology Transfer Agreement"...............................................................11
         1.70     "Territory"...................................................................................11
         1.71     "Third Party".................................................................................11
         1.72     "Unilateral Development Compound"or "UDC".....................................................11
         1.73     "Unilateral Development Compound Product"or "UDC Product".....................................11
         1.74     "Unique Chemical Compound"....................................................................12
         1.75     "Vaccine".....................................................................................12
         1.76     "Valid Claim".................................................................................12
         1.77     Additional Definitions........................................................................12
ARTICLE 2         RESEARCH PROGRAM..............................................................................16
         2.1      General.......................................................................................16
         2.2      Joint Research Committee......................................................................17
         2.3      Joint Research Project Teams..................................................................20
         2.4      Conduct of the Research Program...............................................................21
         2.5      Disclosure of Financial and Other Burdens and Obligations.....................................22
         2.6      Annual Research Plan..........................................................................23

</TABLE>


                                      -ii-


<PAGE>

<TABLE>

<CAPTION>

<S>      <C>                                                                                                   <C>
         2.7      Targets.......................................................................................23
         2.8      Exclusivity...................................................................................30
         2.9      Third Party Opportunities.....................................................................32
         2.10     Gene Therapy and Vaccine Targets..............................................................33
         2.11     Antibody and Diagnostic Rights................................................................35
         2.12     Use of Scientifically-Qualified Targets to Identify
                   Small Molecules for Use Outside of the Inflammation Field. ..................................36
         2.13     Other Permitted Uses of Program Targets.......................................................37
         2.14     Research Program Records......................................................................38
         2.15     Disclosure of Research Program Results........................................................38
         2.16     Material Transfer.............................................................................39
         2.17     Liability.....................................................................................39
         2.18     Subcontractors................................................................................39
ARTICLE 3         DEVELOPMENT PROGRAM...........................................................................40
         3.1      EDC Compounds.................................................................................40
         3.2      Joint Development Committee and Project Teams.................................................41
         3.3      Development Activities........................................................................45
         3.4      Joint Development Costs.......................................................................46
         3.5      Joint Development Budget......................................................................46
         3.6      Discontinued Development......................................................................47
         3.7      Unilateral Development........................................................................48
         3.8      Dropped EDC Compound..........................................................................53
         3.9      Back-Up Compounds.............................................................................53
         3.10     Right to Audit................................................................................54
         3.11     Use of Subcontractors.........................................................................54
         3.12     Pharmacovigilance.............................................................................54
ARTICLE 4         MANUFACTURE AND SUPPLY........................................................................55
         4.1      Clinical Supply...............................................................................55
         4.2      Commercial Supply.............................................................................55
         4.3      Supply Agreement..............................................................................55
         4.4      Use of Subcontractors.........................................................................55
ARTICLE 5         REGULATORY MATTERS............................................................................56
         5.1      Ownership.....................................................................................56
         5.2      Regulatory Coordination.......................................................................57
         5.3      Regulatory Meetings and Correspondence........................................................57
         5.4      Review of Correspondence......................................................................57
         5.5      Assistance....................................................................................58
ARTICLE 6         COMMERCIALIZATION PROGRAM.....................................................................60
         6.1      Objectives for Commercialization of Joint Development Products................................60
         6.2      Joint Commercialization Committee and Project Teams...........................................61
         6.3      Joint Commercialization Committee Responsibilities............................................62
         6.4      Joint Commercialization Project Team Responsibilities.........................................62
         6.5      Decision Making...............................................................................64
         6.6      North America Commercialization Project Team..................................................65
         6.7      Commercialization Strategy and Decision Making................................................68
         6.8      Revenue Booking in North America..............................................................68

</TABLE>


                                     -iii-

<PAGE>

<TABLE>

<CAPTION>

<S>      <C>                                                                                                   <C>
         6.9      Commercialization Expense and Budget..........................................................68
         6.10     Public Statements Regarding Joint Development Products........................................70
         6.11     Compliance with Laws..........................................................................70
         6.12     Unilateral Commercialization..................................................................70
         6.13     Use of Subcontractors.........................................................................72
ARTICLE 7         LICENSES......................................................................................72
         7.1      Millennium Grants.............................................................................72
         7.2      Aventis Grants................................................................................80
         7.3      Retained Rights...............................................................................87
         7.4      Section 365(n) of the Bankruptcy Code.........................................................88
         7.5      Certain Covenants Regarding Ex-Program Products...............................................88
ARTICLE 8         FINANCIAL PROVISIONS..........................................................................88
         8.1      Equity Investment.............................................................................88
         8.2      Pre-tax Profit or Loss In North America.......................................................89
         8.3      Royalties.....................................................................................91
         8.4      Royalty Reports; Payments.....................................................................96
         8.5      Audits........................................................................................96
         8.6      Tax Matters...................................................................................97
         8.7      Currency Exchange.............................................................................97
         8.8      Late Payments.................................................................................98
ARTICLE 9         INTELLECTUAL PROPERTY OWNERSHIP, PROTECTION AND RELATED MATTERS...............................98
         9.1      Ownership.....................................................................................98
         9.2      Prosecution and Maintenance of Patent Rights..................................................99
         9.3      Cooperation...................................................................................99
         9.4      Exploitation of Joint Inventions.............................................................100
         9.5      Third Party Infringement.....................................................................100
         9.6      Other Intellectual Property Infringement.....................................................102
         9.7      Marks for JD Products........................................................................104
ARTICLE 10        CONFIDENTIALITY..............................................................................105
         10.1     Confidential Information.....................................................................105
         10.2     Employee and Advisor Obligations.............................................................105
         10.3     Term.........................................................................................106
         10.4     Publications.................................................................................106
ARTICLE 11        Term and Termination.........................................................................106
         11.1     Term; Extension..............................................................................106
         11.2     Termination For Material Breach..............................................................107
         11.3     Termination Upon HSR Denial..................................................................109
         11.4     Dispute Resolution...........................................................................109
         11.5     Residual Rights..............................................................................109
ARTICLE 12        DISPUTE RESOLUTION...........................................................................110
         12.1     Joint Steering Committee.....................................................................110
         12.2     Referral of Unresolved Matters to Joint Steering Committee...................................110
         12.3     Referral of Unresolved Matters to Executive Officers.........................................111
         12.4     Independent Experts..........................................................................111
         12.5     Non-Binding Mediation........................................................................111

</TABLE>


                                      -iv-
<PAGE>

<TABLE>

<CAPTION>

<S>     <C>                                                                                                   <C>
ARTICLE 13        REPRESENTATIONS, WARRANTIES AND COVENANTS....................................................111
         13.1     Representation of Authority; Consents........................................................111
         13.2     No Conflict..................................................................................112
         13.3     Knowledge of Pending or Threatened Litigation................................................112
         13.4     Employee and Consultant Obligations..........................................................112
         13.5     Burdened Technology Obligations..............................................................113
         13.6     Intellectual Property........................................................................113
         13.7     Disclaimer of Warranty.......................................................................113
ARTICLE 14        Miscellaneous Provisions.....................................................................113
         14.1     Indemnification..............................................................................113
         14.2     Insurance....................................................................................115
         14.3     Governing Law................................................................................115
         14.4     Assignment...................................................................................115
         14.5     Amendments...................................................................................116
         14.6     Change of Control of Millennium..............................................................116
         14.7     Notices......................................................................................117
         14.8     Force Majeure................................................................................117
         14.9     Compliance with Export Regulations...........................................................118
         14.10    Public Announcements.........................................................................118
         14.11    Non-Solicitation.............................................................................118
         14.12    Independent Contractors......................................................................119
         14.13    No Strict Construction.......................................................................119
         14.14    Headings.....................................................................................119
         14.15    No Implied Waivers; Rights Cumulative........................................................119
         14.16    Severability.................................................................................119
         14.17    Execution in Counterparts....................................................................119
         14.18    No Third Party Beneficiaries.................................................................120
         14.19    No Consequential Damages.....................................................................120
ARTICLE 15        HSR FILING...................................................................................120
         15.1     HSR Filing...................................................................................120
         15.2     HSR-Related Definitions......................................................................120

</TABLE>

The following Exhibits are being simultaneously delivered with the execution of
this Agreement as separate documents:

<TABLE>

<CAPTION>

<S>               <C>
Exhibit A         Annual Research Plan for First Contract Year
Exhibit B         Costs and Calculation of Pre-tax Profit or Loss
Exhibit B-1       Principles for Detail Cost
Exhibit B-2       Principles for Calculation of NA/Ex-NA Expense Related to North America
Exhibit B-3       Net Sales Definition
Exhibit B-4       Manufacturing Cost Principles
Exhibit C         Certain Aventis Third Party Agreements
Exhibit D         Certain Millennium Third Party Agreements

</TABLE>


The following Schedules are attached to this Agreement:

                                      -v-
<PAGE>

<TABLE>

<CAPTION>

<S>                  <C>
Schedule 3.2.2       Form of Global Development Plan
Schedule 4.2         Criteria for the Assignment of Responsible Manufacturing Party
Schedule 6.4.4       Form of Global Commercialization Plan

</TABLE>

                                      -vi-

<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                       COLLABORATION AND LICENSE AGREEMENT

This Collaboration and License Agreement dated the 22nd day of June, 2000 (the
"Execution Date") is by and between Millennium Pharmaceuticals, Inc., a
corporation organized and existing under the laws of the State of Delaware and
having its principal office at 75 Sidney Street, Cambridge, Massachusetts 02139
("Millennium"), and Aventis Pharmaceuticals Inc., a corporation organized and
existing under the laws of the State of Delaware and having its principal office
at Route 202-206, P.O. Box 6800, Bridgewater, New Jersey 08807 ("Aventis").

                                  INTRODUCTION

WHEREAS, Millennium and Aventis are each in the business of discovering,
developing and commercializing pharmaceutical products.

WHEREAS, Millennium and Aventis are interested in collaborating in the
identification and validation of targets for use in the discovery of small
molecules and in the discovery, development and commercialization of small
molecules all for use in the prevention and treatment of certain inflammatory
diseases.

WHEREAS, on even date herewith, Millennium and Aventis are entering into an
Investment Agreement, a Technology Development Agreement and a Technology
Transfer Agreement.

NOW, THEREFORE, Millennium and Aventis agree as follows:

                                    ARTICLE 1

                                   DEFINITIONS

When used in this Agreement, each of the following terms shall have the meanings
set forth in this Article I:

     1.1  "ACTIVE". Active means, with respect to a Small Molecule, that the
          Small Molecule (a) [**] in the case of a [**]) a
          Scientifically-Qualified Target with [**], as determined by the Joint
          Research Committee.

     1.2  "AFFILIATE". Affiliate means any corporation, company, partnership,
          joint venture and/or firm which controls, is controlled by, or is
          under common control with a specified person or entity. For purposes
          of this Section 1.2, "control" shall be presumed to exist if one of
          the following conditions is met: (a) in the case of corporate
          entities, direct or indirect ownership of at least fifty percent (50%)
          of the stock or shares having the right to vote for the election of
          directors, and (b) in the case of non-corporate entities, direct or
          indirect ownership of at least fifty percent (50%) of the equity
          interest with the power to direct the management and policies of such
          non-corporate entities. The Parties acknowledge that in the case of
          certain entities organized under the laws of certain countries outside
          of the


                                     Page 1
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

          United States, the maximum percentage ownership permitted by law for a
          foreign investor may be less than fifty percent (50%), and that in
          such case such lower percentage shall be substituted in the preceding
          sentence, provided that such foreign investor has the power to direct
          the management and policies of such entity.

     1.3  "ANNUAL RESEARCH PLAN". Annual Research Plan means the plan to be
          developed by the Joint Research Committee for each Contract Year, to
          be updated as necessary during each Contract Year, setting forth,
          among other things, a master plan for the Research Program during the
          Research Program Term and the matters described in Section 2.6 below.
          Exhibit A sets forth the master plan for the Research Program Term and
          the Annual Research Plan for the First Contract Year.

     1.4  "ANTIBODY". Antibody means a polyclonal or monoclonal antibody,
          whether multiple or single chain, recombinant or naturally occurring,
          whole or fragment and any constructs thereof.

     1.5  "BUSINESS DAY". Business Day means a day on which banking institutions
          in New York, New York and Frankfurt, Germany are open for business.

     1.6  "CHANGE OF CONTROL". Change of Control means (a) a merger or
          consolidation of Millennium and a Significant Pharmaceutical
          Enterprise which results in the voting securities of Millennium
          outstanding immediately prior thereto ceasing to represent at least
          [**] of the combined voting power of the surviving entity immediately
          after such merger or consolidation, or (b) a Significant
          Pharmaceutical Enterprise, together with its Affiliates, becoming the
          beneficial owner of [**] or more of the combined voting power of the
          outstanding securities of Millennium, or (c) the sale or other
          transfer of all or substantially all of Millennium's assets which
          relate to this Agreement to a Significant Pharmaceutical Enterprise.

     1.7  "COMMERCIALIZATION" or "COMMERCIALIZE". Commercialization or
          Commercialize means any and all activities directed to marketing,
          promoting, distributing, offering for sale and selling a product,
          importing a product for sale, conducting Commercial Phase IIIB Studies
          and Phase IV Studies, and manufacturing for commercial sale. When used
          as a verb, "Commercialize" means to engage in Commercialization.

     1.8  "CONFIDENTIAL INFORMATION". Confidential Information means all
          proprietary materials, know-how or other information (whether or not
          patentable) regarding a Party's technology, products, business
          information or objectives, which is designated as confidential in
          writing by the disclosing Party, whether by letter or by the use of an
          appropriate stamp or legend, prior to or at the time any such


                                     Page 2
<PAGE>

          material, know-how or other information is disclosed by the disclosing
          Party to the other Party. Notwithstanding the foregoing to the
          contrary, materials, know-how or other information which is orally,
          electronically or visually disclosed by a Party, or is disclosed in
          writing without an appropriate letter, stamp or legend, shall
          constitute Confidential Information of a Party (a) if the disclosing
          Party, within thirty (30) days after such disclosure, delivers to the
          other Party a written document or documents describing the materials,
          know-how or other information and referencing the place and date of
          such oral, visual, electronic or written disclosure and the names of
          the persons to whom such disclosure was made, or (b) such information
          is of the type that is customarily considered to be confidential
          information by persons engaged in activities that are substantially
          similar to the activities being engaged in by the Parties (including
          without limitation software source code). Notwithstanding the
          foregoing, any technical or financial information of a Party disclosed
          at a meeting of the Joint Research Committee, the Joint Development
          Committee, the Joint Commercialization Committee or the Joint Steering
          Committee (or any subcommittees or project teams of the foregoing) or
          disclosed through an audit report shall constitute Confidential
          Information of a Party unless otherwise specified.

     1.9  "CONTRACT YEAR". Contract Year means (a) with respect to the first
          Contract Year, the period beginning on the Effective Date and ending
          on December 31, 2000 (the "First Contract Year"), and (b) with respect
          to each subsequent Contract Year, the twelve (12) month period
          beginning on the day following the end of the First Contract Year and
          each succeeding twelve (12) month period thereafter during the
          Research Program Term (except that the last Contract Year shall end on
          the fifth anniversary of the Effective Date). Each Contract Year
          (other than the First and last Contract Year) shall be divided into
          four (4) "Contract Quarters" comprised of successive three (3) month
          periods. In the First Contract Year, the first Contract Quarter shall
          end on the first day following the Effective Date that is the last day
          of a calendar quarter, and in the last Contract Year, the last
          Contract Quarter shall end on the fifth anniversary of the Effective
          Date.

     1.10 "CONTROL" or "CONTROLLED". Control or Controlled means with respect to
          any (a) material, item of information, method, data or other know-how,
          or (b) intellectual property right, the possession (whether by
          ownership or license, other than pursuant to this Agreement) by a
          Party or its Affiliates of the ability to grant to the other Party
          access and/or a license as provided herein under such item or right
          without violating the terms of any agreement or other arrangement with
          any Third Party existing before or after the Effective Date.

     1.11 "COVERING", "COVER", or "COVERED". Covering, Cover or Covered means,
          with respect to a Patent Right, that, but for a license granted to a
          party under a Valid Claim included in such Patent Right, the practice
          by such party of an invention claimed in such Patent Right would
          infringe such Valid Claim or in the case of a Patent Right that is a
          patent application, would infringe a Valid Claim in such patent
          application if it were to issue as a patent.


                                     Page 3
<PAGE>

     1.12 "DEVELOPMENT" or "DEVELOP". Development or Develop means, with respect
          to a therapeutic drug candidate that has achieved EDC Status or its
          equivalent (and any related Diagnostic candidates) preclinical and
          clinical drug development activities, including, among other things:
          test method development and stability testing, toxicology,
          formulation, process development, manufacturing scale-up,
          development-stage manufacturing, quality assurance/quality control
          development, statistical analysis and report writing, clinical studies
          and regulatory affairs, product approval and registration. When used
          as a verb, "Develop" means to engage in Development. For the purposes
          of this Agreement, Commercial Phase IIIB Studies or Phase IV Studies
          shall constitute Commercialization.

     1.13 "DIAGNOSTIC". Diagnostic means any product or service that (a)
          identifies patients having a particular disease or having a
          predisposition to a particular disease, and/or (b) defines the
          prognosis or monitors the progress of any disease in a patient and/or
          (c) is used to select between two (2) or more therapeutic or
          prophylactic regimens, wherein at least one such therapeutic or
          prophylactic regimen involves a compound that could be used to treat
          and/or prevent a disease, and where the selected regimen is
          determined, based on the use of such product or service, to be the
          most effective and/or to be the most safe for a patient.

     1.14 "DROPPED EDC COMPOUND". Dropped EDC Compound means an EDC Compound
          that neither Party is Developing.

     1.15 "DROPPED TARGET". Dropped Target means a Scientifically-Qualified
          Target that was under active pursuit pursuant to the Research Program
          as a Program Target or as a Single-Party Research Target but is no
          longer the subject of validation and drug discovery activities
          pursuant to Section 2.7.4.

     1.16 "DRUGGABLE TARGET". Druggable Target means a target (i.e., a nucleic
          acid sequence and/or the protein that it encodes), for which there is
          reasonable evidence (based upon bioinformatics analysis) to suggest
          that such target is of a class that is capable of being (a) modulated
          by a Small Molecule and (b) configured into an assay for Small
          Molecule high throughput screening or used for structure-based Small
          Molecule drug design. By way of example, a Druggable Target may
          include, without limitation, a protein in one of the following
          classes: G protein-coupled receptors, nuclear hormone receptors, ion
          channels and enzymes.

     1.17 "EARLY DEVELOPMENT CANDIDATE STATUS" or "EDC STATUS". Early
          Development Candidate Status or EDC Status means the status that may
          be assigned to a Small Molecule by the Joint Development Committee
          after certain Pre-EDC Research Evaluation activities have been
          completed.

     1.18 "EDC COMPOUND". EDC Compound means a Program Compound that has
          achieved EDC Status in the Research Program, as determined in
          accordance with Section 3.1.


                                     Page 4
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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.19 "EFFECTIVE DATE". Effective Date means the HSR Clearance Date (as
          defined in Article 15) or, if the Parties mutually agree that an HSR
          Filing is not required, July 6, 2000.

     1.20 "EXECUTIVE OFFICERS". Executive Officers means the Chief Executive
          Officer of Aventis or a parent Affiliate of Aventis (or an executive
          of Aventis designated by such Chief Executive Officer) and the Chief
          Executive Officer of Millennium (or an executive of Millennium
          designated by such Chief Executive Officer).

     1.21 "[**] PROPERTY". [**] Property means any information, methods, data,
          or other know-how included in or that relate to, and/or any [**]
          Property" means [**] Property [**] Property" means [**] Property [**].

     1.22 "FDA". FDA means the United States Food and Drug Administration, or a
          successor agency thereto.

     1.23 "FIRST COMMERCIAL SALE". First Commercial Sale means, for each
          Royalty-Bearing Product, on a country-by-country basis, the first
          shipment of Royalty-Bearing Product to a Third Party by the
          Royalty-Paying Party, its Affiliates or sublicensees in a country in
          the Territory after Regulatory Approval has been achieved for such
          Royalty-Bearing Product in such country. Sales for test marketing,
          sampling and promotional uses, clinical trial purposes or
          compassionate or similar use shall not be considered to constitute a
          First Commercial Sale.

     1.24 "FTE". FTE means a full time equivalent person year (consisting of a
          total of 1,760 hours per year) of scientific, technical or managerial
          work on or directly related to the Research Program or the Development
          or Commercialization of Joint Development Compounds or Joint
          Development Products.

     1.25 "GENE THERAPY". Gene Therapy means treatment, prevention or control of
          a disease or condition in humans, or remedying a gene deficiency of
          humans, by genetic modification of human somatic cells or animal
          somatic or germ cells (in vivo, in vitro or ex vivo) with DNA (RNA)
          for the purpose of expressing a protein or oligo(poly)nucleotide
          encoded by such DNA (RNA).

     1.26 "HPB". HPB means the Health Protection Branch of Health Canada, or any
          successor agency thereto.


                                     Page 5
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.27 "IND". IND means (a) (i) an Investigational New Drug Application, as
          defined in the U.S. Federal Food, Drug, and Cosmetic Act, as amended,
          and the regulations promulgated thereunder, that is required to be
          filed with the FDA before beginning clinical testing of a Joint
          Development Product in human subjects, or any successor application or
          procedure and (ii) any foreign counterpart of a U.S. Investigational
          New Drug Application, and (b) all supplements and amendments that may
          be filed with respect to the foregoing.

     1.28 "INFLAMMATION FIELD". Inflammation Field means the prevention, control
          and/or treatment in humans of (a) [**] inflammation (consisting of
          [**]), (b) [**], (c) [**] and/or (d) [**].

     1.29 "INVESTMENT AGREEMENT". Investment Agreement shall mean the Investment
          Agreement entered into by the Parties on date even herewith.

     1.30 "JOINT COMMERCIALIZATION PROJECT TEAM". Joint Commercialization
          Project Team means a team formed pursuant to Section 6.2.

     1.31 "JOINT DEVELOPMENT COMPOUND". Joint Development Compound means an EDC
          Compound that the Parties jointly Develop in accordance with Article
          3.

     1.32 "JOINT DEVELOPMENT PRODUCT" or "JD PRODUCT". Joint Development Product
          or JD Product means a product containing a Joint Development Compound
          as an active ingredient that the Parties jointly Commercialize in
          accordance with Article 6.

     1.33 "JOINT DEVELOPMENT PROJECT TEAM". Joint Development Project Team means
          a team formed pursuant to Section 3.2.

     1.34 "JOINT STEERING COMMITTEE". Joint Steering Committee means a committee
          comprised of an appropriate number of representatives of Millennium
          and Aventis to plan and oversee the activities contemplated by this
          Agreement, as well as the activities of the Parties under the
          Technology Development Agreement and the Technology Transfer
          Agreement, as may be provided in such agreements.

     1.35 "LAWS". Laws means all laws, statutes, rules, regulations, ordinances
          and other pronouncements having the effect of law of any federal,
          national, multinational, state, provincial, county, city or other
          political subdivision, domestic or foreign.

     1.36 "LEAD COMPOUND". Lead Compound means a Program Compound that has been
          selected as a lead by the Joint Research Committee based on lead
          selection criteria agreed upon by the Joint Research Committee
          pursuant to Section 2.4.1.


                                     Page 6
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.37 "LEAD COMPOUND FAMILY". Lead Compound Family means with respect to a
          Lead Compound, such Lead Compound and all Program Compounds that are
          [**] of such Lead Compound in the conduct of the Research Program.

     1.38 "NDA". NDA means (a) (i) a New Drug Application pursuant to 21 U.S.C.
          Section 505(b)(1) submitted to the FDA or any successor application or
          procedure and (ii) any foreign counterpart of a U.S. New Drug
          Application, and (b) all supplements and amendments, including
          supplemental New Drug Applications (and any foreign counterparts),
          that may be filed with respect to the foregoing.

     1.39 "NORTH AMERICA" or "NA". North America or NA means the United States,
          its territories and possessions, and Canada.

     1.40 "PARTY" or "PARTIES". Party means Aventis or Millennium; "Parties"
          means Aventis and Millennium.

     1.41 "PATENT RIGHTS". Patent Rights means all existing patents and patent
          applications and all patent applications hereafter filed, including
          any continuations, continuations-in-part, divisions, provisionals or
          any substitute applications, any patent issued with respect to any
          such patent applications, any reissue, reexamination, renewal or
          extension (including any supplemental patent certificate) of any such
          patent, and any confirmation patent or registration patent or patent
          of addition based on any such patent, and all foreign counterparts of
          any of the foregoing.

     1.42 "PHASE I STUDY". Phase I Study means a clinical study in subjects to
          evaluate the pharmacokinetic and pharmacodynamic properties, maximum
          tolerated dose, dosing interval, and absorption, distribution,
          metabolism and excretion (ADME) of a candidate drug.

     1.43 "PHASE IIA STUDY". Phase IIA Study means a dose exploration, dose
          response, duration of effect, kinetic/dynamic relationship and
          preliminary efficacy and safety study of a candidate drug in the
          target patient population.

     1.44 "PHASE IIB STUDY". Phase IIB Study means a controlled dose ranging
          clinical trial to evaluate further the efficacy and safety of a
          candidate drug in the targeted patient population and to define the
          optimal dosing regimen.

     1.45 "PHASE IIIA STUDY". Phase IIIA Study means a controlled clinical trial
          to confirm with statistical significance the efficacy and safety of
          the drug in larger, targeted patient populations, performed to obtain
          approval of a product application.


                                     Page 7
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.46 "PHASE IIIB STUDY". Phase IIIB Study means a clinical trial intended
          to enhance the profile of a product for a non-approved indication and
          not required or pivotal for approval of a product application. A
          "Development Phase IIIB Study" means a Phase IIIB Study commenced
          prior to the completion of Phase IIIA Studies required for Regulatory
          Approval for the first indication for a Joint Development Product. A
          "Commercial Phase IIIB Study" means a Phase IIIB Study commenced after
          the completion of Phase IIIA Studies required for Regulatory Approval
          for the first indication for a Joint Development Product.

     1.47 "PHASE IV STUDY". Phase IV Study means a study initiated in a country
          after receipt of Regulatory Approval in such country within the
          approved product labeling.

     1.48 "PRE-EDC RESEARCH EVALUATION". Pre-EDC Research Evaluation means any
          and all of the activities relating to the qualification of a Small
          Molecule for EDC Status, including, but not limited to, chemical
          optimization and pre-clinical activities.

     1.49 "PROGRAM COMPOUND". Program Compound means a Small Molecule that (a)
          (i) is in a Party's or any of its Affiliates' possession as of the
          Effective Date, or is [**] by a Party or any of its Affiliates during
          the Research Program Term but [**] the Research Program, (ii) is [**]
          a Program Target and (iii) is selected by the Joint Research Committee
          for Pre-EDC Research Evaluation in the conduct of the Research Program
          or (b) is [**]the Research Program or (c) is otherwise designated a
          Program Compound by the Joint Research Committee; provided however in
          no event shall the [**] Program Compound unless such designation is
          affirmatively agreed to by the Joint Research Committee.

     1.50 "PROGRAM COMPOUND FAMILY". Program Compound Family means, with respect
          to a Program Compound, such Program Compound [**] that are [**] such
          Program Compound in the conduct of the Research Program.

     1.51 "PROGRAM INTELLECTUAL PROPERTY". Program Intellectual Property means
          Program Patent Rights, Program Material, and Program Technology. For
          clarity, Program Intellectual Property includes Research Program
          Chemistry Intellectual Property.

     1.52 "PROGRAM MATERIAL". Program Material means any
          Scientifically-Qualified Targets (including Program Targets), Program
          Compounds, and any material first identified or discovered in the
          conduct of the Research Program, including, without limitation,
          biological materials or chemical compounds such as tissue samples,
          receptors, reagents and screens.


                                     Page 8
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
             Exchange Commission. Asterisks denote omissions.

     1.53 "PROGRAM PATENT RIGHTS". Program Patent Rights means any Patent Rights
          that are Controlled by a Party and that Cover any Program Technology
          or Program Materials.

     1.54 "PROGRAM TARGET". Program Target means [**] which the Joint Research
          Committee has committed to initiate activities in the Research
          Program that relate to (a) in vitro or in vivo modulation of the
          gene corresponding to such target (e.g., through antisense, mouse
          knockout, etc.), (b) drug discovery or similar activities using
          such target, or (c) such other activities related to the validation
          or use of the target in the Inflammation Field as are determined
          appropriate by the Joint Research Committee and identified in the
          Annual Research Plan.

     1.55 "PROGRAM TECHNOLOGY". Program Technology means any invention,
          information, methods, know how, trade secrets, data, or copyright
          (excluding copyrights in North American Promotional Materials) that
          (a) is Controlled by a Party or jointly by the Parties and, (b) (i)
          relates to the Inflammation Field, is utilized in the Research Program
          (but only to the extent so utilized), and either is in a Party's or
          any of its Affiliates' possession as of the Effective Date or is
          discovered or acquired by a Party and/or any of its Affiliates during
          the Research Program Term but outside of the conduct of the Research
          Program, or (ii) is first invented or discovered in the conduct of the
          Research Program or in the course of the Development or
          Commercialization of any Joint Development Compound or Joint
          Development Product. For clarity, Program Technology excludes Program
          Materials.

     1.56 "REGULATORY APPROVAL". Regulatory Approval means any and all approvals
          (including any applicable governmental price and reimbursement
          approvals), licenses, registrations, or authorizations of any federal,
          national, multinational, state, provincial or local regulatory agency,
          department, bureau or other governmental entity necessary for the
          manufacture, use, storage, import, transport, promotion, marketing and
          sale of a product in a country.

     1.57 "RESEARCH PROGRAM". Research Program means the collaborative research
          program to be conducted by the Parties in accordance with the Annual
          Research Plan and this Agreement. For clarity, activities conducted
          pursuant to Sections 2.7.3, 2.10, 2.11 and 2.12 shall not be part of
          the Research Program.

     1.58 "RESEARCH PROGRAM CHEMISTRY INTELLECTUAL PROPERTY". Research Program
          Chemistry Intellectual Property means any invention, information,
          methods, know how, trade secrets, data, copyright or material that
          relate to, or any Program Patent Rights that Cover, any Program
          Compound. "Aventis Research Program Chemistry Intellectual Property"
          means Research Program Chemistry Intellectual Property Controlled by
          Aventis. "Millennium Research Program Chemistry Intellectual Property"
          means Research Program Chemistry Intellectual Property Controlled by
          Millennium.


                                     Page 9
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.59 "ROW". ROW means all the countries in the Territory excluding the
          countries in North America.

     1.60 "ROW MAJOR MARKET COUNTRIES". ROW Major Market Countries means the
          United Kingdom, France, Germany, Spain, Italy and Japan.

     1.61 "ROYALTY-BEARING PRODUCT". Royalty-Bearing Product means a Joint
          Development Product, a UDC Product, a Single-Party Target Product, an
          Ex-Program Product, a GT or Vaccine Product, or an Antibody or
          Diagnostic Product.

     1.62 "ROYALTY-PAYING PARTY". Royalty-Paying Party means, with respect to a
          Royalty-Bearing Product, the Party obligated to pay royalties to the
          other Party under any of the provisions of Section 8.3.

     1.63 "SCIENTIFICALLY-QUALIFIED TARGET" or "SQT". Scientifically-Qualified
          Target or SQT means a target (a) that is [**], and (b) for which [**]
          and/or [**], or such [**] by the Joint Research Committee, of utility
          of such target for the [**] for use as a drug in the [**], based on
          information from (i) [**] (ii) [**], and (iii) [**] or comparable
          technologies, or such other method as may otherwise be determined by
          the Joint Research Committee (PROVIDED THAT in the absence of any such
          determination, each of subsections (i), (ii) and (iii) shall be
          required), in each case performed using [**].

     1.64 "SIGNIFICANT PHARMACEUTICAL ENTERPRISE". Significant Pharmaceutical
          Enterprise means (a) a company (other than Aventis or an Aventis
          Affiliate) which, together with its Affiliates, had worldwide annual
          revenues from the sale of pharmaceutical products in excess of $[**]
          during its most recently completed fiscal year and (b) any Affiliates
          of such company.

     1.65 "SINGLE-PARTY RESEARCH TARGET". Single-Party Research Target means a
          former Program Target that is the subject of validation and/or drug
          discovery activities by only one of the Parties outside of the
          Research Program in accordance with Section 2.7.3. "Aventis
          Single-Party Research Target" means a Single-Party Research Target for
          which Aventis is the Researching Party and "Millennium Single-Party
          Research Target" means a Single-Party Research Target for which
          Millennium is the Researching Party.


                                      Page 10
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

     1.66 "SINGLE-PARTY TARGET PRODUCT". Single-Party Target Product means a
          product that contains as an active ingredient a Small Molecule first
          identified, evaluated or optimized by a Party through the use of a
          Single-Party Research Target, or first identified, evaluated or
          optimized in the Research Program through the use of such target as a
          Program Target prior to its designation as a Single-Party Research
          Target and is developed as a Single Party Target Product. "Aventis
          Single-Party Target Product" means a Single-Party Target Product under
          investigation by Aventis, and "Millennium Single-Party Target Product"
          means a Single-Party Target Product under investigation by Millennium.

     1.67 "SMALL MOLECULE". Small Molecule means a compound that has a molecular
          weight that is no greater than [**]. The term "Small Molecule" shall
          not include any compound that is (A) a [**], (B) a [**], (C) an
          [**], (D) a [**], or (E) a [**] or [**] that acts as an [**].

     1.68 "TECHNOLOGY DEVELOPMENT AGREEMENT". Technology Development Agreement
          means the Technology Development Agreement between Aventis and
          Millennium dated as of the Execution Date.

     1.69 "TECHNOLOGY TRANSFER AGREEMENT". Technology Transfer Agreement means
          the Technology Transfer Agreement between Millennium and Aventis dated
          as of the Execution Date.

     1.70 "TERRITORY". Territory means all the countries of the world.

     1.71 "THIRD PARTY". Third Party means any person or entity other than a
          Party or any of its Affiliates.

     1.72 "UNILATERAL DEVELOPMENT COMPOUND" or "UDC". Unilateral Development
          Compound or UDC means an EDC Compound that one Party Develops in
          accordance with Section 3.7. "Aventis Unilateral Development Compound"
          means a Unilateral Development Compound for which Aventis is the
          Developing Party, and a "Millennium Unilateral Development Compound"
          means a Unilateral Development Compound for which Millennium is the
          Developing Party.

     1.73 "UNILATERAL DEVELOPMENT COMPOUND PRODUCT" or "UDC PRODUCT". Unilateral
          Development Compound Product or UDC Product means a product containing
          a Unilateral Development Compound as an active ingredient. "Aventis
          UDC Product" means a product that contains as an active ingredient an
          Aventis Unilateral Development Compound, and "Millennium UDC Product"
          means a product that contains as an active ingredient a Millennium
          Unilateral Development Compound.


                                      Page 11
<PAGE>

     1.74 "UNIQUE CHEMICAL COMPOUND". Unique Chemical Compound means a Small
          Molecule having a unique arrangement of atoms by virtue of
          composition, connectivity and shape such that it can be or has been
          assigned a Chemical Abstracts Registry number (CAS no.).
          Notwithstanding the foregoing, (a) enantiomeric forms of the same
          molecule, (b) a molecule and its salt form, or (c) a prodrug that is
          metabolized to the same active moiety as the Small Molecule, shall be
          considered the same Unique Chemical Compound.

     1.75 "VACCINE". Vaccine means a prophylactic or therapeutic agent that acts
          by inducing a humoral and/or cell-mediated immune response directed
          specifically against an antigen.

     1.76 "VALID CLAIM". Valid Claim means a claim (a) of any issued, unexpired
          patent which has not been revoked or held unenforceable or invalid by
          a decision of a court or governmental agency of competent jurisdiction
          from which no appeal can be taken, or with respect to which an appeal
          is not taken within the time allowed for appeal, and which has not
          been disclaimed, denied or admitted to be invalid or unenforceable
          through reissue, disclaimer or otherwise, or (b) of any patent
          application which shall not have been cancelled, withdrawn, abandoned
          nor been pending for more than five (5) years from the earliest
          priority date claimed for such application.

     1.77 ADDITIONAL DEFINITIONS. Each of the following definitions is set forth
          in the section of this Agreement indicated below:

<TABLE>

<CAPTION>

         DEFINITION                                             SECTION
<S>     <C>                                                     <C>
         Adjustment Factor                                      Exhibit B-2
         Antibody Option                                        2.11.1
         Antibody Products                                      2.11.1
         Aventis Ex-Program Intellectual Property               1.21
         Aventis Indemnified Parties                            14.1.2
         Aventis Single-Party Research Target                   1.65
         Aventis Single-Party Target Product                    1.66
         Aventis UDC Product                                    1.71
         Back-Up Compounds                                      3.9.1
         Breach Notice                                          11.2.1
         Breaching Party                                        11.2.1
         Burdened Technology                                    2.5.1
         Burdened Technology Obligations                        2.5.1
         Clinical Supply Cost                                   Exhibit B
         Capacity                                               Exhibit B-4
         Capacity Variance                                      Exhibit B-4
         Commercial Phase IIIB Study                            1.44
         Compound Expression of Interest                        3.7.6(c)
         Compound Notification                                  3.7.6(a)

</TABLE>


                                      Page 12
<PAGE>

    Confidential Materials omitted and filed separately with the Securities and
                  Exchange Commission. Asterisks denote omissions.

<TABLE>

<CAPTION>

<S>                                                             <C>
         Compound Response Period                               3.7.6(b)
         Compound Right of First Negotiation                    3.7.6
         Contract Quarter                                       1.9
         Contract Year                                          1.9
         Designation Date                                       Exhibit B-2
         Detail                                                 Exhibit B
         Detail Cost                                            Exhibit B
         Detail Number                                          Exhibit B
         Developing Party                                       3.7.1
         Development Phase IIIB Study                           1.44
         Diagnostic Option                                      2.11.1
         Diagnostic Products or Services                        2.11.1
         DOJ                                                    15.2.1
         EDC Data Package                                       3.1.1
         Efficiency Variance                                    Exhibit B-4
         Energy/Waste & Environmental Costs for the Active
            Production Plants                                   Exhibit B-4
         Essential Pharmacogenomic Product or Service           2.13.1(b)
         [**]                                                   2.12.3
         [**]                                                   2.12.3
         [**]                                                   2.12.4
         [**]                                                   2.12.2
         Excess Recovery                                        9.5.4
         Field Force Expense                                    Exhibit B
         FTE Cost                                               Exhibit B
         FTE Rate                                               Exhibit B
         FTC                                                    15.2.2
         G&A Expense                                            Exhibit B
         GT Option                                              2.10.1
         GT Products                                            2.10.1
         Global Commercialization Plan                          6.3.4
         Global Development Plan                                3.2.2(h)
         HSR Act                                                15.2.3
         HSR Clearance Date                                     15.2.4
         HSR Filing                                             15.2.5
         Intellectual Property                                  13.6.1
         Inventory Write-offs                                   Exhibit B-4
         Investment Agreement                                   8.1
         Joint Research Committee                               2.2.1
         Joint Research Project Team                            2.2.1
         Labor Capacity                                         Exhibit B-4
         Lead Regulatory Party                                  5.1.1
         Line Cost                                              Exhibit B-4
         Marks                                                  9.7.1
         Manufacturer Period Costs                              Exhibit B-4
         Material Cost                                          Exhibit B-4

</TABLE>


                                      Page 13
<PAGE>

<TABLE>

<CAPTION>

<S>                                                             <C>
         Material Price Variance                                Exhibit B-4
         Millennium Ex-Program Intellectual Property            1.21
         Millennium Indemnified Parties                         14.1.1
         Millennium Single-Party Research Target                1.63
         Millennium Single-Party Target Product                 1.64
         Millennium UDC Product                                 1.71
         NA Commercialization Expense                           Exhibit B
         NA Development Cost                                    Exhibit B
         NA License Fees                                        Exhibit B
         NA Marketing Expense                                   Exhibit B
         NA Medical Expense                                     Exhibit B
         NA Percentage                                          Exhibit B-2
         NA Period Costs                                        Exhibit B
         NA/Ex-NA Commercialization                             6.1.3
         NA/Ex-NA Commercialization Expense                     Exhibit B
         NA/Ex-NA Development                                   3.2.4(a)
         NA/Ex-NA Development Cost                              Exhibit B
         NA/Ex-NA Expense                                       Exhibit B
         NA/Ex-NA License Fees                                  Exhibit B
         NA/Ex-NA Marketing Expense                             Exhibit B
         NA/Ex-NA Medical Expense                               Exhibit B
         NA/Ex-NA Period Costs                                  Exhibit B
         Net Sales                                              Exhibit B-3
         Non-Breaching Party                                    11.2.1
         Non-Selling Party                                      9.5.4
         North America Commercialization Budget                 6.6.1(c)
         North America Development                              3.2.4(a)
         North America Promotional Materials                    6.6.3(a)
         North America Commercialization                        6.1.3
         Notice of Disagreement                                 5.4
         Notice of Discontinuance                               3.6.1
         Operator Labor Costs                                   Exhibit B-4
         Opt-Out Phase                                          8.3.2
         Other Cost of Goods                                    Exhibit B-4
         Overhead Costs                                         Exhibit B-4
         Owning Party                                           9.5.2(b)
         Patent Prosecution                                     9.2.1
         Period Costs                                           Exhibit B-4
         Potential Antibody Target                              2.11.1
         Potential Diagnostic Target                            2.11.1
         Potential GT Target                                    2.10.1
         Potential Vaccine Target                               2.10.1
         Pre-tax Profit or Loss                                 Exhibit B
         Product Development                                    Exhibit B-4
         Product Expression of Interest                         6.12.3
         Product Notification                                   6.12.1

</TABLE>


                                      Page 14
<PAGE>


<TABLE>

<CAPTION>

<S>                                                             <C>
         Product Related Costs                                  Exhibit B-4
         Product Response Period                                6.12.2
         Product Right of First Negotiation                     6.12
         Project Start-up                                       Exhibit B-4
         Quality Testing Costs                                  Exhibit B-4
         Related Joint Development Product                      8.3.1
         Related UDC Product                                    8.3.2
         Relevant Calendar Year                                 Exhibit B-2
         Relevant Five-Calendar-Year Period                     Exhibit B-2
         Relevant Global Inflammation Sales                     Exhibit B-2
         Relevant NA Inflammation Sales                         Exhibit B-2
         Relevant Period Costs                                  Exhibit B
         Relevant Products                                      Exhibit B-2
         Representative                                         Exhibit B
         Research Program Term                                  2.1.2
         Researching Party                                      2.7.3(a)
         Revaluation                                            Exhibit B-4
         ROW Commercialization                                  6.5.1
         ROW Development                                        3.2.4(b)
         ROW Period Cost                                        Exhibit B
         Selling Party                                          9.5.4
         Spending Variance                                      Exhibit B-4
         SPRT Compounds                                         2.7.3(b)
         Standard Cost                                          Exhibit B
         Supply Price                                           Exhibit B
         Target Expression of Interest                          2.7.3(f)(iii)
         Target Notification                                    2.7.3(f)(i)
         Target Response Period                                 2.7.3(f)(ii)
         Target Right of First Negotiation                      2.7.3(f)
         Third Party Opportunity                                2.9.1
         Vaccine Option                                         2.10.1
         Vaccine Products                                       2.10.1
         Volume Variance                                        Exhibit B-4
         Work Center Capacity                                   Exhibit B-4
         Work Center Costs                                      Exhibit B-4

</TABLE>


                                      Page 15
<PAGE>

Confidential Materials omitted and filed separately with the Securities and
             Exchange Commission. Asterisks denote omissions.

                                   ARTICLE 2

                                RESEARCH PROGRAM

2.1      GENERAL.

         2.1.1    Objective.

                  (a)      The Parties shall collaborate in carrying out the
                           Research Program as set forth in the then current
                           Annual Research Plan, with the global objectives of
                           (i) [**]  Scientifically-Qualified Targets and
                           Program Targets identified and/or validated in the
                           Research Program, consistent with the resources
                           allocated to such activities under the Annual
                           Research Plan, and (ii) [**] of EDC Compounds
                           with potential utility in the Inflammation Field,
                           consistent with the resources allocated to such
                           activities under the Annual Research Plan.

                  (b)      It is anticipated that during the initial years of
                           the Research Program, [**] to the Research
                           Program [**] of the Research Program. [**] of the
                           Research Program, [**] to the Research Program [**]
                           will be [**] in the [**] of the Research Program.

                  (c)      It is intended that, to the extent practicable, both
                           Parties will participate in the full range of
                           activities to be conducted in the Research Program,
                           including without limitation target identification
                           and validation, assay configuration, high throughput
                           screening and Pre-EDC Research Evaluation of Program
                           Compounds, all of the foregoing subject to the
                           Parties' respective capabilities and capacities to
                           perform such activities.

                  (d)      It is intended that the Research Program will be
                           conducted as a unified collaborative effort with
                           activities by the Parties carried out at each Party's
                           respective facilities as the foregoing may be
                           outlined in the Annual Research Plan.

                  (e)      It is also intended that, during the Research Program
                           Term, the Parties will each be conducting broader
                           target identification and validation, assay
                           configuration, high throughput screening and Pre-EDC
                           Research Evaluation of Small Molecules not
                           specifically


                                      Page 16
<PAGE>

                           directed to the Inflammation Field and conducted
                           outside of the Research Program.

                  (f)      It is also intended, notwithstanding subsection (e)
                           above, that during the Research Program Term the
                           Parties shall collaborate in making available for the
                           Research Program Small Molecule chemical libraries as
                           set forth in the then current Annual Research Plan,
                           with the global objectives of maximizing the quantity
                           and quality of the EDC Compounds with potential
                           utility in the Inflammation Field consistent with the
                           resources allocated to such activities under the
                           Annual Research Plan; PROVIDED THAT neither Party
                           shall be obligated to disclose to the other Party the
                           chemical structure of any compound in any chemical
                           library Controlled by such Party unless and until
                           such compound is identified and confirmed as Active
                           against a Program Target or is otherwise designated a
                           Program Compound by the Joint Research Project Team.

         2.1.2    TERM. The term of the Research Program (the "Research Program
                  Term") shall commence on the Effective Date and end on the
                  fifth anniversary of the Effective Date, unless (a) earlier
                  terminated pursuant to the provisions of Article 11 or (b)
                  extended pursuant to the provisions of Section 11.1.

2.2      JOINT RESEARCH COMMITTEE.

         2.2.1    FORMATION AND MEMBERSHIP. As soon as practicable after the
                  Execution Date, Aventis and Millennium shall establish a Joint
                  Research Committee (the "Joint Research Committee") comprised
                  of three (3) representatives designated by Aventis and three
                  (3) representatives designated by Millennium, each of whom
                  shall have experience and seniority sufficient to enable him
                  or her to make decisions on behalf of the Party he or she
                  represents; provided that Aventis and Millennium may designate
                  an appropriate number of additional representatives from time
                  to time. The Joint Research Committee shall include at least
                  one Development representative from each Party. From time to
                  time during the Research Program Term, the Joint Research
                  Committee shall establish one or more Joint Research Project
                  Teams (each, a "Joint Research Project Team") to implement
                  various aspects of the Annual Research Plan. Such committees
                  shall be governed in the same manner and subject to the
                  relevant requirements as set forth herein for the Joint
                  Research Committee.

         2.2.2    ADMINISTRATIVE MATTERS. The Joint Research Committee shall
                  appoint a chairperson from among its members, which shall
                  rotate semi-annually between the representatives from
                  Millennium and the representatives from Aventis. The
                  chairperson shall be responsible for calling meetings of the
                  Joint Research Committee and for leading the meetings. A Joint
                  Research Committee member of the Party hosting a meeting of
                  the Joint Research


                                      Page 17
<PAGE>

                  Committee shall serve as secretary of that meeting. The
                  secretary of the meeting shall prepare and distribute to all
                  members of the Joint Research Committee minutes of the meeting
                  sufficiently in advance of the next meeting to allow adequate
                  review and comment prior to the meeting. Such minutes shall
                  provide a description in reasonable detail of the discussions
                  had at the meeting and a list of any actions, decisions or
                  determinations approved by the Joint Research Committee.
                  Minutes of each Joint Research Committee meeting shall be
                  approved or disapproved, and revised as necessary, at the next
                  meeting. Final minutes of each meeting shall be distributed to
                  the members of the Joint Research Committee by the
                  chairperson.

         2.2.3    DECISION MAKING. Each Party shall have one vote on the Joint
                  Research Committee (and each Joint Research Project Team).
                  Both Parties must vote in the affirmative to allow the Joint
                  Research Committee (or Joint Research Project Team) to take
                  any action that requires the vote of the Joint Research
                  Committee or a Joint Research Project Team. If the Joint
                  Research Committee is unable to reach unanimous agreement,
                  such issue shall be resolved in accordance with the provisions
                  of Article 12. If a Joint Research Project Team is unable to
                  reach unanimous agreement on any matter, such matter shall be
                  referred to the Joint Research Committee.

         2.2.4    MEETINGS.

                  (a)      The Joint Research Committee shall meet at least four
                           (4) times per Contract Year (except that
                           proportionately fewer meetings shall be held in a
                           Contract Year with fewer than 12 months). Such
                           meetings shall be held at such times and places as
                           are mutually agreed upon by the Joint Research
                           Committee and shall be conducted in person. By
                           approval of the chairperson, where such approval may
                           not unreasonably be withheld, representatives may
                           participate in any meeting of the Joint Research
                           Committee by means of conference telephone or similar
                           communications equipment by means of which all
                           persons participating in the meeting can hear each
                           other.

                  (b)      Each Party shall use commercially reasonable efforts
                           to cause its representatives to attend the meetings
                           of the Joint Research Committee in person. If a
                           Party's representative is unable to attend a meeting,
                           such Party may designate an alternate representative
                           to attend such meeting in place of the absent
                           representative. In addition, each Party may, at its
                           discretion, invite additional employees, and, with
                           the consent of the other Party, consultants or
                           scientific advisors, to attend the meetings of the
                           Joint Research Committee.


                                      Page 18
<PAGE>

                  (c)      Either Party may also convene a special meeting of
                           the Joint Research Committee for the purpose of
                           resolving disputes or for the purpose of reviewing
                           (or making) a decision pertaining to the designation
                           of a target as a Scientifically-Qualified Target or a
                           Program Target by providing ten (10) Business Days
                           written notice to the other Party.

         2.2.5    RESPONSIBILITIES. The Joint Research Committee shall be
                  responsible for, among other things:

                  (a)      overseeing the Research Program;

                  (b)      providing a forum for consensual decision making;

                  (c)      reviewing recommendations from and advising the Joint
                           Research Project Teams;

                  (d)      reviewing needs in areas other than projects, but
                           necessary to support projects;

                  (e)      preparing and approving each Annual Research Plan for
                           each Contract Year after the First Contract Year;

                  (f)      appointing one or more Joint Research Project Teams,
                           as may be appropriate, to implement the Annual
                           Research Plan;

                  (g)      monitoring the Parties' compliance with their
                           respective obligations under the Annual Research
                           Plan, including the accomplishment of key objectives,
                           the devotion of an appropriate number of FTEs to the
                           Research Program and the expenditure of significant
                           out-of-pocket expenses;

                  (h)      reviewing and approving any amendments to the Annual
                           Research Plan and evaluating any substantive
                           departures by either Party from the Annual Research
                           Plan;

                  (i)      evaluating any Burdened Technology Obligations and
                           deciding whether to accept Burdened Technology into
                           the Research Program;

                  (j)      determining whether a target is a
                           Scientifically-Qualified Target;

                  (k)      selecting which Scientifically-Qualified Targets the
                           Parties wish to designate as Program Targets;

                  (l)      determining which research projects will be pursued
                           in the Research Program and which will be
                           discontinued;


                                      Page 19
<PAGE>

                  (m)      monitoring reports submitted by the Parties pursuant
                           to the Annual Research Plan; and

                  (n)      reviewing and commenting upon (but not approving) the
                           patent filing strategies of the Parties as provided
                           in Article 9.

         2.2.6    PIPELINE REVIEW. Promptly following the Effective Date, the
                  Joint Research Committee shall convene to review both Parties'
                  pre-EDC pipelines of SQT and Program Compound candidates to
                  determine which shall be accepted into the Research Program.
                  Each Party shall identify all Burdened Technology Obligations
                  relating to such Party's pre-EDC pipelines of SQT and Program
                  Compound candidates that the Joint Research Committee
                  identifies as desirable for inclusion in the Research Program.

2.3      JOINT RESEARCH PROJECT TEAMS

         2.3.1    FORMATION OF JOINT RESEARCH PROJECT TEAMS. Aventis and
                  Millennium shall each make its initial designation of its
                  representatives not later than thirty (30) days after the
                  formation of a Joint Research Project Team. Either Party may
                  change its designees to any Joint Research Project Team at any
                  time upon written notice to the other Party.

         2.3.2    Responsibilities. The Joint Research Project Teams shall be
                  responsible for, among other things:

                  (a)      implementing aspects of the Annual Research Plan
                           assigned to such Joint Research Project Team by the
                           Joint Research Committee;

                  (b)      recommending Scientifically-Qualified Targets for
                           designation as Program Targets;

                  (c)      recommending to the Joint Research Committee which
                           research projects will be pursued in the Research
                           Program and which will be discontinued; and

                  (d)      recommending to the Joint Development Committee
                           (after consultation with the Joint Research
                           Committee) Program Compounds for qualification for
                           EDC Status.

         2.3.3    SPECIAL MEETING. Either Party may convene a special meeting of
                  the appropriate Joint Research Project Team for the purpose of
                  reviewing (or making) a recommendation concerning whether a
                  Program Compound has qualified for EDC Status by providing ten
                  (10) Business Days written notice to the other Party.


                                      Page 20
<PAGE>

2.4      CONDUCT OF THE RESEARCH PROGRAM.

         2.4.1    The Joint Research Committee shall adopt project progression
                  guidelines, including back-up selection criteria, similar to
                  guidelines set forth in Appendix E to the Annual Research
                  Plan. The Parties shall conduct the Research Program in
                  accordance with such project progression guidelines. Each
                  Party shall use commercially reasonable efforts to conduct the
                  activities of the Research Program which are assigned to it in
                  the Annual Research Plan.

         2.4.2    Each Party shall devote a substantially equal number of FTEs
                  to the Research Program activities and expend substantially
                  similar amounts in significant out-of-pocket expenditures
                  directly related to the Research Program, each over the course
                  of the Research Program. All FTE utilization and significant
                  out-of-pocket expenditures shall either be expressly provided
                  for in the Annual Research Plan or approved by the Joint
                  Research Committee.

         2.4.3    Each Party shall submit periodic reports to the Joint Research
                  Committee, as may be required by the Annual Research Plan,
                  detailing its activities under the Research Program. The Joint
                  Research Committee shall use such periodic reports to monitor
                  the Parties' respective contributions to the Research Program.
                  The Joint Research Committee may amend the Annual Research
                  Plan as necessary to maintain substantial equality in
                  resources devoted and participation by the Parties over the
                  course of the Research Program.

         2.4.4    If either Party believes that there is a material imbalance in
                  resources devoted to, or participation by the Parties in, the
                  Research Program, such Party may submit the matter to the
                  Joint Research Committee in writing. Taking into account
                  historical and prospective participation and resource devotion
                  of the Parties during the current Contract Year and the
                  immediately following Contract Year, the Joint Research
                  Committee shall take such steps as may be reasonably necessary
                  to ensure substantial equality in resources devoted and
                  participation by the Parties in the Research Program. At the
                  request of a Party, the other Party shall permit an
                  independent, certified accountant appointed by the requesting
                  Party, at reasonable times and upon reasonable notice but no
                  more than once per year, to examine, at the sole cost of the
                  requesting Party, the records of the other Party to verify the
                  accuracy of any reports submitted by the other Party to the
                  Joint Research Committee regarding the level of resources
                  devoted to the Research Program by such Party

         2.4.5    Each Party shall identify one of its representatives to serve
                  as a program director with responsibility for overseeing that
                  Party's day-to-day activities relating to the Research Program
                  and to serve as a contact person for coordinating Research
                  Program activities between the Parties.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

2.5      DISCLOSURE OF FINANCIAL AND OTHER BURDENS AND OBLIGATIONS.

         2.5.1    The Parties acknowledge that certain materials, and data and
                  information relating thereto, Controlled by a Party may
                  include financial or other obligations to Third Parties[**],
                  and that the use of such [**] Program Technology or Program
                  Materials in the Research Program and the Development and
                  Commercialization of products resulting from the use of such
                  [**], may result [**] may (1) [**] to certain Program
                  Technology [**] under this Agreement, (2) [**], or that
                  certain information [**], (3) [**] by this Agreement or (4)
                  [**] under this Agreement relative to the rights of such Party
                  in the absence of any such grant of rights [**]).

         2.5.2    Each Party acknowledges its obligation to inform the other
                  Party of Burdened Technology Obligations relating to any
                  Program Technology or Program Materials which it provides to
                  the Research Program. With respect to any proposed
                  Scientifically-Qualified Target, all Burdened Technology
                  Obligations related thereto shall be identified and described
                  in reasonable detail in writing by the Party that Controls
                  such target to the Joint Research Committee at such time as
                  such target is proposed for inclusion in the Research Program
                  as an SQT.

         2.5.3    The Burdened Technology Obligations shall be considered for
                  all Program Technology or Program Materials prior to its
                  inclusion in the Research Program. By way of example, proposed
                  Scientifically-Qualified Targets will only be permitted into
                  the Research Program after the Joint Research Committee has
                  evaluated the nature and scope of the Burdened Technology
                  Obligations.

         2.5.4    [**] by the Joint Research Committee, [**] (a) [**] (including
                  without limitation, [**] in the [**] with respect to [**], or
                  (b) to [**] of the [**] with respect to such [**] that would
                  [**]relating to such [**] pursuant to Sections 7.1.1(d),
                  7.1.2(d) and 7.1.3(d), in the case of Aventis, and Sections
                  7.2.1(d), 7.2.2(d) and 7.2.3(d), in the case of Millennium,
                  [**] the other Party, [**].

         2.5.5    The Party [**] shall be [**] to the Joint Research Committee
                  [**] provided that with regard to [**] the use of such [**]
                  the Party [**] shall not be [**] the other Party [**] on
                  such Party's [**] thereof.


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<PAGE>

Confidential Materials omitted and filed separately with the Securities and
             Exchange Commission. Asterisks denote omissions.

2.6      ANNUAL RESEARCH PLAN.

         2.6.1    The Joint Research Committee shall prepare and approve the
                  Annual Research Plan for every Contract Year (other than the
                  First Contract Year) at least sixty (60) days prior to the
                  commencement of such Contract Year. The Annual Research Plan
                  for the First Contract Year is set forth in Exhibit A to this
                  Agreement.

         2.6.2    The Joint Research Committee shall update and amend, as
                  appropriate, the then-current Annual Research Plan from time
                  to time.

         2.6.3    Each Annual Research Plan shall contain the specific research
                  objectives to be achieved during the Contract Year, the
                  specific activities to be performed under the Research Program
                  and the timeline for performing such activities, and the Party
                  which shall be responsible for performing each of the
                  activities.

         2.6.4    Each Annual Research Plan shall be consistent with the other
                  terms and conditions of this Agreement, including the
                  objectives set forth in Section 2.1.1, and shall be
                  substantially the same in form, including the items itemized
                  in, the Annual Research Plan attached as Exhibit A.

2.7      TARGETS.

         2.7.1    [**]

                  (a)      During the Research Program Term, each Party shall
                           use commercially reasonable efforts to [**]
                           identified and qualified in the Research Program,
                           [**], using the technologies, data and materials
                           specified in such Annual Research Plan.

                  (b)      Each Party shall [**] provided, however, a Party
                           shall [**] which it is [**] accordance with
                           the provisions of this Section 2.7.1.


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      During the Research Program Term, each Party shall,
                           [**], make [**] that it [**] could reasonably qualify
                           as a [**] together with [**] relating to the [**]
                           for use in [**].

                  (d)      At each meeting of the Joint Research Committee, the
                           Joint Research Committee shall identify [**]
                           based on its review of the criteria set forth in
                           the Annual Research Plan and the Burdened Technology
                           Obligations associated therewith.

         2.7.2    PROGRAM TARGETS. Once the Joint Research Committee has
                  designated a target as [**], the Joint Research Committee
                  will periodically consider whether it wishes to use [**]
                  for identification of Small Molecules suitable for use as
                  drugs [**] and, among other things, conduct the activities set
                  forth in the definition of "Program Target". If the Joint
                  Research Committee wishes to so use the [**] and conduct such
                  activities, then the Joint Research Committee shall designate
                  [**] as a Program Target and the Joint Research Committee
                  will prepare and approve an amendment to the Annual Research
                  Plan to reflect the activities to be undertaken by the Parties
                  with respect to such Program Target.

         2.7.3    SINGLE-PARTY RESEARCH TARGETS.

                  (a)      If at any time during the Research Program Term (i)
                           (A) a Party desires not to participate in further
                           validation or drug discovery activities with respect
                           to a Program Target and so notifies the other Party,
                           or (B) a Party fails to exercise commercially
                           reasonable efforts in undertaking the Research Plan
                           activities with respect to a Program Target pursuant
                           to the Annual Research Plan, and does not remedy such
                           failure within [**] following written notice of such
                           failure from the other Party, and (ii) the other
                           Party provides written notice to the Joint Research
                           Committee that it wishes to continue to participate
                           in further validation or drug discovery Cactivities
                           with respect to such target within [**] of receipt of
                           the notice from the discontinuing Party or the
                           expiration of such cure period, then the Joint
                           Research Committee shall designate such target a
                           Single-Party Research Target (and such target shall
                           no longer constitute a Program Target) and the other
                           Party shall have the right, outside of the Research
                           Program, to continue to engage in such activities
                           with respect to such target [**] (such Party being
                           referred to herein as the "Researching Party").


                                      Page 24
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (b)      The Researching Party shall have access to all
                           Program Technology relating to the Single-Party
                           Research Target and all Program Materials relating to
                           the Single-Party Research Target, excluding Program
                           Compounds except as follows: (i) all Program
                           Compounds that are Active against such Single-Party
                           Research Target and any Small Molecules that are
                           members of the corresponding Program Compound Family,
                           PROVIDED, HOWEVER, that use of any such Small
                           Molecule that is not Active against such Single-Party
                           Research Target shall be limited to internal research
                           purposes only, and (ii) all Small Molecules within
                           the Lead Compound Family of a Lead Compound directed
                           to such Single-Party Research Target ((i) and (ii)
                           collectively "SPRT Compounds"). Any rights of the
                           Non-Researching Party to use such Lead Compound
                           Family in the Research Program shall be suspended
                           until discontinuation of all activities by the
                           Researching Party relating to such Lead Compound
                           Family with respect to such Single-Party Research
                           Target.

                  (c)      Notwithstanding the foregoing, a Party shall not have
                           the right to pursue as a Single-Party Research
                           Target, a Program Target which the other Party has
                           decided not to continue to pursue in the Research
                           Program if such target has the same biological
                           activity and the same relevance in Small Molecule
                           drug discovery as another Program Target in the
                           Research Program.

                  (d)      As soon as reasonably practicable after the
                           designation of a target as a Single-Party Research
                           Target by the Joint Research Committee, the Party
                           that is not the Researching Party shall provide the
                           Researching Party with any Program Technology and all
                           Program Material as may be specified in subsection
                           (b) in its Control.

                  (e)      The Researching Party shall have the right to:

                           (i)      research and Develop Small Molecules
                                    identified through the use of a Single-Party
                                    Research Target for use [**], using such
                                    Single-Party Research Target in such
                                    research and Development, as necessary, and


                                      Page 25
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                           (ii)     Commercialize any resulting Single-Party
                                    Target Product [**], subject to the royalty
                                    obligation set forth in Section 8.3.3.

                  (f)      Notwithstanding the foregoing, if a Party intends to
                           research, Develop or Commercialize [**] any Small
                           Molecules identified through the use of a
                           Single-Party Research Target including those Small
                           Molecules allocated in accordance with Section
                           2.7.3(b) in collaboration with a Third Party, or
                           grant a license to a Third Party to do any of the
                           foregoing, such Party shall provide the other Party
                           with the opportunity to negotiate terms under which
                           the other Party would collaborate or obtain a license
                           with respect to such activities (a "Target Right of
                           First Negotiation"), provided that a Target Right of
                           First Negotiation shall not apply to the retention of
                           a contract sales force or to a product distribution
                           or contract manufacturing arrangement or other
                           outsourced marketing, advertising or promotion
                           activities (unless such arrangement is with a
                           Significant Pharmaceutical Enterprise). A Target
                           Right of First Negotiation shall operate as follows:

                           (i)      The Researching Party shall promptly notify
                                    the other Party in writing (the "Target
                                    Notification") of its intention to seek a
                                    collaborator or licensee for researching,
                                    Developing and/or Commercializing [**] a
                                    Small Molecule identified through the use of
                                    such Single-Party Research Target and shall
                                    provide to the other Party a reasonably
                                    detailed written description of such
                                    proposed collaboration or license,
                                    including, without limitation, the identity
                                    of the target and the data, information,
                                    material or results and Small Molecules
                                    identified, evaluated or developed using
                                    such target including those Small Molecules
                                    allocated in accordance with Section
                                    2.7.3(b)

                           (ii)     Within [**] of its receipt of the Target
                                    Notification (the "Target Response Period"),
                                    the other Party shall notify the Researching
                                    Party of its interest, if any, in initiating
                                    discussions regarding such proposed
                                    collaboration or license.


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                           (iii)    In the event that the other Party notifies
                                    the Researching Party prior to the
                                    termination of the Target Response Period
                                    that it has an interest in participating in
                                    such proposed collaboration or obtaining
                                    such license rights (a "Target Expression of
                                    Interest"), then the Parties shall negotiate
                                    in good faith in an effort to reach a
                                    definitive agreement regarding such
                                    collaboration or license for a period of up
                                    to [**] from the date of the Researching
                                    Party's receipt of the Target Expression of
                                    Interest.

                           (iv)     In the event that the Parties reach a
                                    definitive agreement with respect to such
                                    collaboration or license pursuant to
                                    subsection (iii), such target shall no
                                    longer be designated a Single-Party Research
                                    Target and the rights and obligations of the
                                    Parties with respect to such target and any
                                    Small Molecules identified, developed or
                                    evaluated through the use of such target
                                    including those Small Molecules allocated in
                                    accordance with Section 2.7.3(b) shall be
                                    governed by the terms of such definitive
                                    agreement and not this Agreement.

                           (v)      In the event that (A) the other Party fails
                                    to notify the Researching Party prior to the
                                    termination of the Target Response Period
                                    that it is interested in collaborating with
                                    or obtaining a license from the Researching
                                    Party with respect to such Single-Party
                                    Research Target, or (B) the other Party
                                    notifies the Researching Party prior to the
                                    termination of the Target Response Period
                                    that it has no interest in collaborating
                                    with or obtaining a license from the
                                    Researching Party with respect to such
                                    Single-Party Research Target, or (C) the
                                    other Party timely provides the Researching
                                    Party with an Expression of Interest but the
                                    Parties fail to reach definitive agreement
                                    within the [**] period specified in
                                    subsection (iii), then the Researching Party
                                    shall be free to enter into a collaboration
                                    or license with a Third Party with respect
                                    to such Single-Party Research Target;
                                    PROVIDED, HOWEVER, that the Researching
                                    Party may not enter into any collaboration
                                    or license with a Third Party [**] to the
                                    Third Party, [**] to the non-Researching
                                    Party.


                                      Page 27
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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                           (vi)     For the duration of the Target Response
                                    Period, and if the other Party timely
                                    delivers the Target Expression of Interest,
                                    the [**] term specified in Section
                                    2.7.3(f)(iii), the Researching Party may
                                    discuss with a Third Party the general
                                    outline of such collaboration or license;
                                    provided however, that the Researching Party
                                    shall not negotiate such collaboration or
                                    license with a Third Party, enter into any
                                    agreements with such Third Party or propose
                                    terms to such Third Party on which the
                                    Researching Party would be willing to
                                    consummate such collaboration or license.

                  (g)      For the avoidance of doubt, a Program Target which
                           becomes a Single-Party Research Target shall continue
                           to remain a Scientifically-Qualified Target and the
                           non-Researching Party shall continue to have the
                           right to use such Scientifically-Qualified Target to
                           the extent provided in Section 2.12.

         2.7.4    DROPPED TARGETS.

                  (a)      If at any point in time (i) neither Party desires to
                           continue validation and drug discovery activities
                           with respect to a Program Target, (ii) both Parties
                           fail to exercise commercially reasonable efforts to
                           conduct validation and drug discovery activities with
                           respect to such target and do not cure such failure
                           or both Parties fail to exercise commercially
                           reasonable efforts in undertaking such validation and
                           drug discovery activities and neither cures such
                           failure within [**] after receipt of written notice
                           from the other Party asserting such failure (PROVIDED
                           THAT if the first Party to receive such written
                           notice responds within such [**] period
                           with a notice to the other Party asserting that such
                           other Party has also failed to exercise commercially
                           reasonable efforts in undertaking such validation and
                           drug discovery activities, both written notices
                           shall, for purposes of this subsection, be deemed to
                           have been given concurrently on the date that the
                           first notice was given), (iii) the Joint Research
                           Project Team decides to discontinue validation and
                           drug discovery activities with respect to such
                           target, or (iv) the Researching Party fails to
                           exercise commercially reasonable efforts to conduct
                           validation and drug discovery activities with respect
                           to a Single-Party Research Target, then such target
                           shall thereafter be deemed a Dropped Target and not a
                           Program Target or a Single Party Research Target, as
                           applicable.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (b)      Either Party shall thereafter during the Research
                           Program Term have the right to pursue such target as
                           a Single-Party Research Target, PROVIDED THAT such
                           Party first gives written notice of its desire to the
                           other Party, together with any data, results, or
                           information in its Control relating to such target
                           and not already provided to the other Party. If the
                           other Party does not give notice of its desire to
                           pursue such target within [**], such target shall
                           thereafter be a Single-Party Research Target and not
                           a Dropped Target and the Researching Party's rights
                           and obligations with respect to such Single-Party
                           Research Target shall be as set forth in Section
                           2.7.3.

                  (c)      If the other Party desires to participate in such
                           research and/or drug discovery activities with
                           respect to such target, such target shall thereafter
                           be a Program Target and not a Dropped Target, and the
                           Annual Research Plan shall be appropriately amended
                           to include such activities in the Research Program.

                  (d)      For the avoidance of doubt, a Program Target or
                           Single Party Target which becomes a Dropped Target
                           shall continue to remain a Scientifically-Qualified
                           Target and both Parties shall continue to have the
                           right to use such Scientifically-Qualified Target to
                           the extent provided in Section 2.12.

         2.7.5    [**] Research Program [**]. [**] the Research Program, [**]
                  this Agreement [**] the Parties [**] shall be as follows:

                  (a)      Each Party shall [**] by such Party [**] by a Party
                           shall [**], the other Party.

                  (b)      Each Party shall [**] and any Program [**]. Any such
                           [**] shall be [**] and a [**] and [**] by a Party
                           [**] by the relevant provisions set forth [**],
                           PROVIDED, HOWEVER, that (i) the [**] shall [**] and
                           (ii) the [**] of a Party set forth in [**] with
                           respect to the [**] Product shall only apply in the
                           event that [**] the other Party in the [**] Product.


                                      Page 29
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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      With respect to each [**] that has been used [**],
                           the Parties shall [**] in the [**] in the [**]. In
                           the event that the Parties [**] reach a final
                           agreement [**] for a period of up to [**] from the
                           date on which the Parties [**]. If the Parties enter
                           into a final agreement [**] of the Parties [**]
                           (which shall be[**] in the same [**] in accordance
                           with the provisions [**] shall be governed by the
                           terms of [**]. In the event that (i) the Parties [**]
                           or (ii) [**] with respect to [**] the [**] period
                           specified above, then [**] from which the Parties
                           shall [**]. The[**] of the Parties [**], as necessary
                           to have [**] which Party shall make the first
                           selection). Each target selected from the [**] shall
                           [**] shall be deemed to be [**], as the case may be,
                           and the [**] a Party shall be governed by the
                           relevant provisions set forth in [**], PROVIDED,
                           HOWEVER, that the [**] shall not apply [**].

2.8      EXCLUSIVITY.

         2.8.1    GENERAL. During the Research Program Term, and subject to the
                  exceptions set forth in Section 2.8.3, neither Party nor its
                  Affiliates shall, either alone or in collaboration with a
                  Third Party, engage in any activity, the goal of which is

                  (a)      the identification or validation of targets for the
                           discovery of Small Molecules intended for use [**];
                           or

                  (b)      the discovery and Pre-EDC Research Evaluation of
                           Small Molecules intended for use[**],

                           in each case except pursuant to the Research Program
                           and excepting Small Molecules that have achieved EDC
                           Status prior to the Effective Date.

         2.8.2    [**] LICENSING. During the Research Program Term, and subject
                  to the exceptions set forth in Section 2.8.3, [**] (a) [**]
                  license to, or any [**] license, any target, or any Patent
                  Rights Covering, or know-how embodied in, the use of such
                  target, [**], or (b) [**] any license to, or any option to
                  license, any target, or any Patent Rights Covering, or
                  know-how embodied, in the use of such target, [**] such
                  license or option grant [**].

         2.8.3    EXCEPTIONS. The prohibitions set forth in Sections 2.8.1 and
                  2.8.2 are not intended to apply to any activity directed to
                  the identification or validation of targets or the discovery
                  and Pre-EDC Research Evaluation of Small Molecules,


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                    Commission. Asterisks denote omissions.

                  (a)      where such activity is undertaken in fulfillment of
                           an obligation of a Party existing as of the Execution
                           Date pursuant to an agreement that is set forth in
                           EXHIBIT C or EXHIBIT D;

                  (b)      where such activity is undertaken with respect to any
                           assets Controlled by a Party as of the Execution Date
                           and identified in EXHIBIT C or EXHIBIT D;

                  (c)      where such activity is undertaken in fulfillment of
                           an obligation of a Party pursuant to an agreement
                           with an academic, research or other non-commercial
                           institution, which agreement provides that such Party
                           shall be granted the right (or the option to obtain
                           the right), with the right to grant sublicenses to
                           the other Party, [**] to use any targets, Small
                           Molecules and related know-how for the research,
                           Development and Commercialization under this
                           Agreement;

                  (d)      where a Party's involvement in such activity results
                           from such Party's acquisition of or by a Third Party
                           (by merger or otherwise), which Third Party, prior to
                           such acquisition or merger, was already engaged in
                           such activity, and such Party does not expand the
                           scope of, or financial commitment to, such activity;
                           provided that no Program Technology that was
                           identified or developed during the course of the
                           Research Program and no Program Materials are
                           disclosed to the Third Party; and provided further
                           that to the extent any other technology Controlled by
                           the Party in the form of biological materials (e.g.
                           genes, gene fragments, vectors, cell lines, cells,
                           organelles, DNA and DNA fragments, proteins and
                           peptides) or chemical compounds (e.g. small molecule
                           and natural product compounds and libraries), or any
                           data relating to the foregoing, are disclosed to such
                           Third Party, such Third Party shall (i) undertake in
                           writing not to use such technology or data in any
                           activities prohibited by Section 2.8.1, and (ii)
                           agree that the other Party shall be a third party
                           beneficiary of such undertaking. For clarity, the
                           exception as set forth in this subsection (d) shall
                           not apply where substantially all of such Third
                           Party's activities are encompassed by Section 2.8.1

                  (e)      where such activity is undertaken by a Party with
                           respect to a Single-Party Research Target to the
                           extent otherwise permitted by the provisions of this
                           Agreement; or

                  (f)      where such activity is undertaken with respect to a
                           Third Party Opportunity, pursuant to the relevant
                           provisions of Section 2.9.


                                      Page 31
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         2.8.4    OTHER PERMITTED ACTIVITIES. For purposes of clarity,
                  activities that are not prevented by the prohibitions set
                  forth in Section 2.8.1 include, without limitation, the
                  following:

                  (a)      either Party may, outside of the conduct of the
                           Research Program, engage in target identification and
                           validation activities and/or drug discovery or
                           Pre-EDC Research Evaluation of Small Molecules [**],
                           subject to the provisions of Section 2.8.1;

                  (b)      either Party may, outside of the conduct of the
                           Research Program, engage in Pre-EDC Research
                           Evaluation of or Development of a Small Molecule for
                           use [**], provided that such Small Molecule (i) is
                           in-licensed from a Third Party, (ii) has achieved the
                           equivalent of EDC Status at the time of such
                           in-licensing (as long as the structure of such Small
                           Molecule is not modified), and (iii) is not generally
                           known or known by such Party to exert its action
                           through a Program Target; and

                  (c)      either Party may, outside of the conduct of the
                           Research Program, engage in Pre-EDC Research
                           Evaluation or Development of a Small Molecule for use
                           [**], provided that such Small Molecule (i) had
                           achieved the equivalent of EDC Status as of the
                           Effective Date, and (ii) the structure of such Small
                           Molecule is not modified.

         2.8.5    SCOPE OF RESTRICTIONS. The Parties agree that, given the high
                  costs and significant risks involved in discovering and
                  developing pharmaceutical products, and given that the Parties
                  will be exchanging Confidential Information in order to
                  perform the Research Program, the exclusive relationship
                  between them regarding the Research Program and the
                  Inflammation Field, which is reflected herein, is a fair and
                  efficient means to reach a satisfactory conclusion from their
                  cooperative efforts.

2.9      THIRD PARTY OPPORTUNITIES.

         2.9.1    In the event that a Party is presented with an opportunity to
                  collaborate with a Third Party (a "Third Party Opportunity")
                  with respect to

                  (a)      the identification and/or validation of a target or
                           family of related targets (not to exceed [**] targets
                           in number) for the discovery of Small Molecules for
                           use [**], and/or


                                      Page 32
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (b)      the discovery and/or Pre-EDC Research Evaluation of a
                           Small Molecule and its related lead series [**],

                           then such Party may pursue such Third Party
                           Opportunity, but only in the manner provided in this
                           Section 2.9, such Party shall present the Third Party
                           Opportunity, including all material terms and
                           conditions relating thereto, to the Joint Research
                           Committee for the Joint Research Committee's
                           consideration for inclusion in the Research Program.

         2.9.2    The Joint Research Committee shall then have [**] to decide
                  whether to pursue such Third Party Opportunity. In the event
                  that the Joint Research Committee elects to pursue such Third
                  Party Opportunity, then the Parties shall negotiate with the
                  Third Party that presented such Third Party Opportunity in a
                  good faith effort to reach an agreement with the Third Party
                  whereby the Third Party Opportunity can be included in the
                  Research Program. In the event that the Parties and the Third
                  Party that presented such Third Party Opportunity reach an
                  agreement to include such Third Party Opportunity in the
                  Research Program, then

                           (i)      the Third Party Opportunity shall be
                                    included in the Research Program; and

                           (ii)     the Annual Research Plan shall be
                                    appropriately amended to include, without
                                    limitation, provisions for the sharing by
                                    the Parties of the costs associated with the
                                    Third Party Opportunity.

         2.9.3    In the event that the Joint Research Committee does not elect
                  to pursue such Third Party Opportunity or the Parties fail,
                  despite a good faith effort, to reach agreement with the Third
                  Party that presented such Third Party Opportunity to include
                  the Third Party Opportunity in the Research Program, then the
                  Party that was initially presented with such Third Party
                  Opportunity shall have the right to pursue such Third Party
                  Opportunity outside of the conduct of the Research Program,
                  PROVIDED, HOWEVER, that such Party shall not pursue such Third
                  Party Opportunity outside of the conduct of the Research
                  Program if the target that is the subject of such Third Party
                  Opportunity is a Program Target or if the Small Molecule that
                  is the subject of such Third Party Opportunity is generally
                  known or is known by such Party to exert its action through a
                  Program Target.


                                      Page 33
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

2.10     GENE THERAPY AND VACCINE TARGETS.

         2.10.1   With respect to each Program Target that has relevance for
                  Gene Therapy or Vaccines (a "Potential GT Target" or a
                  "Potential Vaccine Target", as the case may be), Aventis shall
                  have an option (a "GT Option" or "Vaccine Option", as the case
                  may be) to exclusively license Millennium's rights in such
                  Program Target, if any, to validate and use such Potential GT
                  Target or Potential Vaccine Target, as the case may be, to
                  discover and evaluate Gene Therapy and/or Vaccine products
                  ("GT Products" or "Vaccine Products", as the case may be) [**]
                  and to exclusively license Millennium's rights in such Program
                  Target, if any, to Develop and Commercialize such GT Products
                  or Vaccine Products, as the case may be.

         2.10.2   Each GT Option and Vaccine Option will expire [**] after the
                  designation of the underlying target as a Program Target by
                  the Joint Research Committee. With respect to any Potential GT
                  Target or Potential Vaccine Target, Aventis may exercise
                  either the GT Option or the Vaccine Option, or both the GT
                  Option and the Vaccine Option.

         2.10.3   In the event that Aventis elects to exercise a GT Option
                  and/or a Vaccine Option, Aventis shall provide written notice
                  of such exercise to Millennium prior to the expiration of the
                  [**] option period and, thereupon, Aventis shall automatically
                  be granted the licenses set forth in Section 7.1.4(a) or
                  7.1.4(b), as the case may be, and Aventis' subsequent
                  discovery and development work with respect to such Potential
                  GT Target or Potential Vaccine Target in the Gene Therapy or
                  Vaccine area, as applicable, shall be funded separately by
                  Aventis and conducted outside of the Research Program, any
                  Global Development Plan or any Global Commercialization Plan.


                                      Page 34
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         2.10.4   In the event that, with respect to any Potential GT Target or
                  Potential Vaccine Target, (a) Aventis does not exercise the GT
                  Option or the Vaccine Option within the [**] option period for
                  the GT Option or the Vaccine Option, then Aventis shall no
                  longer be entitled to a license to Millennium's Gene Therapy
                  or Vaccine rights, and (b) Aventis fails to exercise
                  commercially reasonable efforts to research, Develop and
                  Commercialize a GT Product or a Vaccine Product based on the
                  use of such Potential GT Target or Potential Vaccine Target
                  and does not remedy such failure within [**] following written
                  notice of such failure from Millennium, then Aventis' license
                  to Millennium's Gene Therapy or Vaccine rights, as applicable,
                  with respect to such Potential GT Target or Potential Vaccine
                  Target and such Gene Therapy or Vaccine rights, as

                  applicable, shall be nonexclusive, subject to the payment of
                  royalties under Section 8.3.5.

         2.10.5   During the period that any license granted to Aventis pursuant
                  to this Agreement is in effect, Aventis shall provide
                  Millennium with an annual report concerning the status of its
                  research, Development and Commercialization efforts with
                  respect to such Potential GT Target or Potential Vaccine
                  Target.

2.11     ANTIBODY AND DIAGNOSTIC RIGHTS.

         2.11.1   With respect to each Program Target that has relevance for the
                  development of Antibody-based therapeutics or Diagnostics (a
                  "Potential Antibody Target" or a "Potential Diagnostic
                  Target", as the case may be), Millennium shall have an option
                  (an "Antibody Option" or a "Diagnostic Option", as the case
                  may be) to exclusively license Aventis' rights in such Program
                  Target, if any, to validate and use such Potential Antibody
                  Target or Potential Diagnostic Target, as the case may be, to
                  discover and evaluate Antibody-based therapeutic products
                  and/or Diagnostics ("Antibody Products" or "Diagnostic
                  Products or Services", as the case may be) [**] and to
                  exclusively license Aventis' rights in such Program Target, if
                  any, to Develop and Commercialize such Antibody Products or
                  Diagnostic Products or Services.

         2.11.2   Each Antibody Option and Diagnostic Option will expire [**]
                  after the designation of the underlying target as a Program
                  Target by the Joint Research Committee. With respect to any
                  Potential Antibody Target or Potential Diagnostic Target,
                  Millennium may exercise either the Antibody Option or the
                  Diagnostic Option, or both the Antibody Option and the
                  Diagnostic Option.


                                      Page 35
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         2.11.3   In the event that Millennium elects to exercise an Antibody
                  Option and/or a Diagnostic Option, Millennium shall provide
                  written notice of such exercise to Aventis prior to the
                  expiration of the [**] option period and, thereupon,
                  Millennium shall automatically be granted the licenses set
                  forth in Section 7.2.4(a) or 7.2.4(b) and Millennium's
                  subsequent discovery and development work with respect to such
                  Potential Antibody Target or Potential Diagnostic Target in
                  the antibody or diagnostic area, as applicable, shall be
                  funded separately by Millennium and conducted outside of the
                  Research Program, any Global Development Plan or any Global
                  Commercialization Plan.

         2.11.4   In the event that, with respect to any Potential Antibody
                  Target or Potential Diagnostic Target, (a) Millennium does not
                  exercise the Antibody Option or the Diagnostic Option within
                  the [**] option period for the Antibody Option or the
                  Diagnostic Option, then Millennium shall no longer be entitled
                  to a license to Aventis' Antibody or Diagnostic rights, and
                  (b) Millennium fails to exercise commercially reasonable
                  efforts to research, Develop and Commercialize an Antibody
                  Product or Diagnostic Product or Service based on the use of
                  such Potential Antibody Target or Potential Diagnostic Target
                  and does not remedy such failure within [**] following written
                  notice of such failure from Aventis, then Millennium's license
                  to Aventis' antibody or diagnostic rights, as applicable, with
                  respect to such Potential Antibody Target or Potential
                  Diagnostic Target and such antibody or diagnostic rights, as
                  applicable, shall be nonexclusive, subject to the payment of
                  royalties under Section 8.3.5.

         2.11.5   During the period that any license granted to Millennium
                  pursuant to this Agreement is in effect, Millennium shall
                  provide Aventis with an annual report concerning the status of
                  its research, Development and Commercialization efforts with
                  respect to such Potential Antibody Target or Potential
                  Diagnostic Target.

2.12     USE OF SCIENTIFICALLY-QUALIFIED TARGETS TO IDENTIFY SMALL MOLECULES
         [**].

         2.12.1   Each Party shall [**] for purposes of the identification,
                  evaluation and optimization of [**], PROVIDED THAT any [**]
                  identified, evaluated or optimized [**]

                  (a)      [**] in an indication [**] or

                  (b)      be the same [**] Compound as (i) any Program [**]),
                           (ii) any [**] Compound [**] by the Parties, (iii) any
                           [**] Compound [**] by a Party, or (iv) with respect
                           to [**].


                                      Page 36
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

          2.12.2  Any product Developed pursuant to this Section 2.12 [**]. For
                  clarity, [**] Products, [**] Products and [**] Products that
                  are [**] pursuant to the relevant provisions of this Agreement
                  [**] .

          2.12.3  Each Party hereby agrees that, [**] under agreements [**],
                  it will [**] pursuant to [**] for use solely [**] under
                  the terms of this Agreement, [**] in such [**] Products,
                  [**] and any [**] Product shall contain [**] Product and
                  was [**] in connection with a [**] Product. Any such
                  [**] Data [**] pursuant to this Section 2.12.3 shall be
                  deemed to be Confidential Information [**] in the
                  Research Program and/or as permitted under the applicable
                  license grants set forth in Article 7.

          2.12.4  In addition to its obligations pursuant to Section 2.12.3,
                  each Party agrees that, [**] under agreements [**] , it will
                  [**] relating to [**] to the extent [**] activities related to
                  (a) the validation of such Scientifically-Qualified Target in
                  the [**] and/or (b) the [**] for use in the [**] (e.g.,
                  including, but not limited to, [**]. Any such [**] disclosed
                  pursuant to this Section 2.12.4 shall be deemed to be
                  Confidential Information [**] in the Research Program and/or
                  as permitted under the license grants set forth in Article 7.
                  For purposes of clarity, it is understood that nothing in this
                  Section 2.12.4 shall [**] to the [**].

         2.12.5   If (a) [**] the Research Program, and (b) such [**] of the
                  Research Program [**] of such Program Target in the Research
                  Program, but [**] such Party is [**] of the Research Program.
                  Notwithstanding the foregoing, [**] such Program [**] of the
                  Research Program.

         2.12.6   If a Party [**], and such [**] by such Party [**] in the
                  Research Program, such Party [**] with respect to Research
                  Program [**] Party within the [**] of the Research Program.

2.13     OTHER PERMITTED USES OF PROGRAM TARGETS.

         2.13.1   Notwithstanding the provisions of Section 2.11, each Party
                  shall have the non-exclusive right to use
                  Scientifically-Qualified Targets in association with UDC
                  Products, Single-Party Target Products, GT Products, Vaccine
                  Products, Antibody Products and Ex-Program Products, the
                  Development and Commercialization of which such Party is
                  permitted to undertake in accordance with this Agreement:

                  (a)      for internal research purposes; and


                                      Page 37
<PAGE>


                  (b)      to develop a Diagnostic used to ascertain the
                           predisposition of an individual to respond favorably
                           or unfavorably to the administration of such UDC
                           Products, Single-Party Target Products, GT Products,
                           Vaccine Products, Antibody Products and Ex-Program
                           Products, where such Diagnostic is required by
                           applicable regulatory authorities to be utilized
                           prior to the administration of any such therapeutic
                           product, or where such Party reasonably determines
                           that such Diagnostic would be reasonably necessary
                           for such therapeutic product to achieve significant
                           market penetration (an "Essential Pharmacogenomic
                           Product or Service").

2.14     RESEARCH PROGRAM RECORDS.

         2.14.1   All work conducted by either Party in the course of the
                  Research Program shall be completely and accurately recorded,
                  in sufficient detail and in good scientific manner, in
                  separate laboratory notebooks. On reasonable notice, and at
                  reasonable intervals, each Party shall have the right to
                  inspect and copy all such records of the other Party
                  reflecting Program Technology or work done under the Research
                  Program, to the extent reasonably required to carry out its
                  respective obligations and to exercise its respective rights
                  hereunder. Notwithstanding the definition of "Confidential
                  Information", all such records shall constitute Confidential
                  Information of the Party creating such records. The Parties
                  acknowledge and agree that neither Party guarantees the
                  success of the Research Program tasks undertaken hereunder.

         2.14.2   In order to protect the Parties' Patent Rights under U.S. law
                  in any inventions conceived or reduced to practice during or
                  as a result of the Research Program, each Party agrees to
                  maintain a policy which requires its employees to record and
                  maintain all data and information developed during the
                  Research Program in such a manner as to enable the Parties to
                  use such records to establish the earliest date of invention
                  and/or diligence to reduction to practice. At a minimum, the
                  policy shall require such individuals to record all inventions
                  generated by them in standard laboratory notebooks which are
                  dated and corroborated by non-inventors on a regular,
                  contemporaneous basis.

2.15     DISCLOSURE OF RESEARCH PROGRAM RESULTS. Subject to restrictions imposed
         by a Party's confidentiality obligations to any Third Party, each Party
         will disclose to the other all Program Technology discovered, invented,
         or made by such Party during the course of the Research Program and
         that is useful in or relates to the Research Program, including,
         without limitation, information regarding potential
         Scientifically-Qualified Targets, Small Molecules identified in the
         Research Program through the use of Program Targets, activities of such
         Small Molecules, derivatives, and results of in vitro and in vivo
         studies, assay techniques and new assays. Such Program Technology will
         be promptly disclosed to the other Party,


                                      Page 38
<PAGE>

         with meaningful discoveries or advances being communicated as promptly
         as practicable after such information is obtained or its significance
         is appreciated. Each Party will provide the other with copies of the
         raw data generated in the course of the Research Program, if reasonably
         necessary to the other Party's work under the Research Program. Any
         information disclosed pursuant to this Section 2.15 may be used by the
         other Party solely for the purposes of the Research Program or as
         otherwise expressly permitted in this Agreement. For clarity, nothing
         in this Section 2.15 shall be deemed to require a Party to disclose to
         the other Party the actual sequence of any target being pursued in the
         Research Program unless and until such target is designated as a
         Scientifically-Qualified Target.

2.16     MATERIAL TRANSFER. In order to facilitate the Research Program, either
         Party may provide to the other Party certain Program Materials (other
         than Program Compounds or Program Targets) Controlled by the supplying
         Party (other than under this Agreement) for use by the other Party in
         furtherance of the Research Program. Except as otherwise provided under
         this Agreement, all such Program Materials delivered to the other Party
         shall remain the sole property of the supplying Party, shall be used
         only in furtherance of the Research Program and solely under the
         control of the other Party and its Affiliates, shall not be used or
         delivered to or for the benefit of any Third Party without the prior
         written consent of the supplying Party, and shall not be used in
         research or testing involving human subjects. The Program Materials
         supplied under this Section 2.16 must be used with prudence and
         appropriate caution in any experimental work, since not all of their
         characteristics may be known. THE MATERIALS ARE PROVIDED "AS IS" AND
         WITHOUT ANY REPRESENTATION OR WARRANTY, EXPRESS OR IMPLIED, INCLUDING
         WITHOUT LIMITATION ANY IMPLIED WARRANTY OF MERCHANTABILITY OR OF
         FITNESS FOR ANY PARTICULAR PURPOSE OR ANY WARRANTY THAT THE USE OF THE
         MATERIALS WILL NOT INFRINGE OR VIOLATE ANY PATENT OR OTHER PROPRIETARY
         RIGHTS OF ANY THIRD PARTY.

2.17     LIABILITY. In connection with conduct of the Research Program, each
         Party shall be responsible for, and hereby assumes, any and all risks
         of personal injury or property damage attributable to the negligent
         acts or omissions of that Party or its Affiliates, and their respective
         directors, officers, employees and agents.

2.18     SUBCONTRACTORS. Either Party may perform some of its obligations under
         the Research Program through one or more subcontractors; provided that
         (a) none of the rights of the other Party hereunder are diminished or
         otherwise adversely affected as a result of such subcontracting, (b)
         such Party obtains the written approval of the other Party prior to
         engaging any subcontractor, which approval shall not be unreasonably
         withheld or delayed, and (c) the subcontractor undertakes in writing
         obligations of confidentiality and non-use regarding the other Party's
         Confidential Information which are substantially the same as those
         undertaken by Aventis and Millennium pursuant to Article 10 hereof. In
         the event a Party performs one or more of its obligations under the
         Research Program


                                      Page 39
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         through a subcontractor, then such Party shall at all times be
         responsible for the performance of such subcontractor. For the
         avoidance of doubt, it is understood that an Affiliate of a Party shall
         not be deemed to be a subcontractor of such Party. For clarity, it is
         understood that the provisions of Section 2.18(b) do not apply to
         contracts for (i) tissue procurement and analysis, (ii) sequencing,
         (iii) protein and peptide production and analysis, (iv) purchasing
         tools or services for target validation (e.g., transgenic mice,
         antibodies, or antisense molecules), and (v) purchasing tools or
         services for the performance of affinity-based interactions and other
         contractual arrangements of a similar nature, PROVIDED, HOWEVER, that
         significant out-of-pocket costs must be approved in accordance with
         Section 2.4.2.

                                   ARTICLE 3

                               DEVELOPMENT PROGRAM

3.1      EDC Compounds.

         3.1.1    The Joint Research Committee shall notify the Joint
                  Development Committee in writing when a Joint Research Project
                  Team has recommended a Program Compound for EDC Status. Such
                  notification shall (1) identify the Program Compound with
                  specificity, (2) identify the related Program Target, if any,
                  and (3) identify the Back-Up Compounds in accordance with
                  Section 3.9. Such notification shall be accompanied by any
                  pertinent data, information, results and materials relating to
                  the foregoing available to the Joint Research Committee (the
                  "EDC Data Package").

         3.1.2    If the Joint Development Committee believes that the EDC Data
                  Package is (a) complete, it shall approve the EDC Data Package
                  and such Program Compound shall be deemed to have achieved EDC
                  Status, or (b) insufficient to make a determination whether to
                  Develop and Commercialize such EDC Compound, it shall
                  promptly, but in no event later than [**] following receipt of
                  the EDC Data Package, notify the Joint Research Committee and
                  specifically identify any additional data, information,
                  results or materials which should be provided.

         3.1.3    Each Party shall, as soon as possible, but in all cases within
                  [**] after the Joint Development Committee has approved the
                  EDC Data Package as complete, provide the Joint Development
                  Committee with written notification of its interest in
                  Developing such EDC Compound. Such notification shall be
                  provided under seal. Failure by a Party to provide written
                  notification within such [**] period shall be deemed to
                  constitute an indication that such Party is not interested in
                  Developing such EDC Compound.



                                      Page 40
<PAGE>

         3.1.4    Once the Parties have provided notification under seal of
                  their respective interests in Developing such EDC Compound,
                  the Joint Development Committee, or its designee, shall unseal
                  both Party's respective notifications, and designate the
                  characterization of such EDC Compound (i.e., Joint Development
                  Compound, Unilateral Development Compound or Dropped EDC
                  Compound) for the purposes of this Agreement based on the
                  interests expressed in the Parties' written notifications.

                  (a)      JOINT DEVELOPMENT COMPOUND. If both Parties have
                           notified the Joint Development Committee of their
                           interest in Developing the EDC Compound, then such
                           compound shall be developed jointly by the Parties as
                           a Joint Development Compound, subject to the terms of
                           this Agreement.

                  (b)      UNILATERAL DEVELOPMENT COMPOUND. If only one Party
                           has notified the Joint Development Committee of its
                           interest in Developing the EDC Compound, then,
                           subject to the provisions of Section 3.9.2, such
                           compound shall be developed unilaterally by such
                           Party as a Unilateral Development Compound, subject
                           to the terms of this Agreement.

                  (c)      DROPPED EDC COMPOUND. If neither Party has notified
                           the Joint Development Committee of its interest in
                           Developing the EDC Compound, then such EDC Compound
                           shall be deemed a Dropped EDC Compound, subject to
                           the terms of this Agreement.

3.2      JOINT DEVELOPMENT COMMITTEE AND PROJECT TEAMS.

         3.2.1    FORMATION OF JOINT DEVELOPMENT COMMITTEE. As soon as
                  reasonably necessary, and in any event prior to the
                  identification of the first EDC Compound, the Parties shall
                  establish a Joint Development Committee to oversee the
                  Development of all Joint Development Compounds. As soon as
                  practicable after designation of each EDC Compound as a Joint
                  Development Compound, the Joint Development Committee shall
                  establish a Joint Development Project Team for such Joint
                  Development Compound. The Joint Development Committee shall be
                  comprised of an equal number of Millennium and Aventis
                  representatives and shall include at least one marketing
                  representative from each Party, with each Party having one
                  vote. Each Joint Development Project Team shall be comprised
                  of Millennium and Aventis representatives and shall include at
                  least one marketing representative, with each Party having one
                  vote. In addition, the Joint Development Committee and each
                  Joint Development Project Team shall appoint a Chairperson and
                  otherwise follow the organizational and meeting procedures set
                  forth in Article 2 with respect to the Joint Research
                  Committee and Joint Research Project Teams, respectively.


                                      Page 41
<PAGE>

         3.2.2    JOINT DEVELOPMENT COMMITTEE RESPONSIBILITIES. The Joint
                  Development Committee shall be responsible for:

                  (a)      determining the completeness of, and whether to
                           approve, an EDC Data Package;

                  (b)      overseeing the Development of all Joint Development
                           Compounds;

                  (c)      providing a forum for consensual decision making;

                  (d)      reviewing recommendations from and advising the Joint
                           Development Project Teams;

                  (e)      approving target product profiles for Joint
                           Development Compounds;

                  (f)      making modifications to and performing quarterly
                           monitoring of progress of studies (including
                           quarterly review of NA/Ex-NA Development Costs, NA
                           Development Costs and activities against the Global
                           Development Plan) and proposing additional product
                           studies;

                  (g)      reviewing needs in areas other than projects but
                           necessary to support the projects: E.G. project
                           progression guidelines and criteria, development
                           processes and systems, SOPs, etc.; and

                  (h)      reviewing and approving the Global Development Plan
                           for each Joint Development Compound, which shall
                           address the items outlined in Schedule 3.2.2 (the
                           "Global Development Plan"), and any updates thereto,
                           including, without limitation:

                           (i)      reviewing each Global Development Plan and
                                    ensuring that such Plan addresses the items
                                    outlined in Schedule 3.2.2;

                           (ii)     ensuring that the Global Development Plan
                                    provides for the Development of Joint
                                    Development Compounds on a global basis;

                           (iii)    approving the Global Development Plans and
                                    identifying key Joint Development Project
                                    Team objectives, the Lead Regulatory Partner
                                    for each Joint Development Compound,
                                    expected associated resources, risk factors,
                                    manufacturing strategy and timelines related
                                    to the Development of each Joint Development
                                    Compound, Go/No Go decision points and
                                    relevant decision criteria and, where
                                    appropriate, decision trees; and


                                      Page 42
<PAGE>


                           (iv)     indicating how resources are expected to be
                                    provided by both Parties to support the
                                    Global Development Plans (consistent with
                                    the provisions of Section 3.3), including
                                    reviewing budgets for NA/Ex-NA Development
                                    Costs and NA Development Costs (which, for
                                    purposes of clarity, do not include ROW
                                    Development costs that are not relevant to
                                    NA/Ex-NA Development) approved by the Joint
                                    Development Project Teams, and monitoring
                                    the allocation and assignment of North
                                    America Development and NA/Ex NA Development
                                    activities between the Parties to ensure
                                    such allocation is consistent with the
                                    provision of Section 3.3.2.

         3.2.3    JOINT DEVELOPMENT PROJECT TEAM RESPONSIBILITIES. The Joint
                  Development Project Team shall be responsible for (i)
                  Developing the applicable Joint Development Product in a
                  manner directed to ensure its marketability (as determined by
                  the marketing representatives of each Party on the Joint
                  Development Project Team) and approvability; and (ii)
                  preparing the Global Development Plan for the applicable Joint
                  Development Product; and (iii) implementing the North America
                  Development and NA/Ex-NA Development of the applicable Joint
                  Development Compounds in accordance with the Global
                  Development Plan for such compound, as well as overseeing the
                  day-to-day operational activities related to North America
                  Development and NA/Ex-NA Development of the Joint Development
                  Compound, including:

                  (a)      preparing and annually updating the Global
                           Development Plan for such Joint Development Compound,
                           and submitting the same to the Joint Development
                           Committee for review and approval;

                  (b)      implementing the North America Development and NA/Ex
                           NA Development of a Joint Development Compound in
                           accordance with the Global Development Plan;

                  (c)      preparing and approving protocols for pre-clinical
                           studies and Phase I Studies, Phase IIA Studies, Phase
                           IIB Studies, Phase IIIA Studies and Development Phase
                           IIIB Studies, pharmaceutical stability studies and
                           manufacturing scale-up studies related to North
                           America Development and NA/Ex NA Development of the
                           applicable Joint Development Compound, consistent
                           with the mandate that each such study conducted
                           should, to the extent possible and to the extent
                           consistent with the best interests of the Joint
                           Development Product globally, be suitable for use in
                           the maximum number of the major pharmaceutical
                           markets;

                  (d)      overseeing pre-clinical studies, Phase I Studies,
                           Phase IIA Studies, Phase IIB Studies, Phase IIIA
                           Studies and Development Phase IIIB


                                      Page 43
<PAGE>

                           Studies in accordance with the Global Development
                           Plan for the applicable Joint Development Compound,
                           including specifying timelines and priorities and
                           making recommendations to the Joint Development
                           Committee regarding which Party, or whether a Third
                           Party, should be responsible for the various North
                           America Development and NA/Ex-NA Development
                           activities;

                  (e)      reviewing and commenting on material regulatory
                           correspondence and submissions relating to North
                           America Development and NA/Ex-NA Development and
                           facilitating the exchange of all data, information,
                           material or results relating to the Development of
                           the Joint Development Compound;

                  (f)      establishing procedures for the collection, sharing
                           and reporting of adverse event information related to
                           the Joint Development Compound and making
                           recommendations to the Joint Development Committee
                           with respect to any appropriate actions to be taken;

                  (g)      recommending a target product profile for the Joint
                           Development Product to the Joint Development
                           Committee, including indications for which the Joint
                           Development Product will be Commercialized, key
                           labeling claims required for commercial success of
                           the Joint Development Product given the competitive
                           environment, and any other key product features and
                           benefits which will be used to develop or support a
                           promotional message for the Joint Development
                           Product;

                  (h)      preparing and approving budgets for NA Development
                           Costs and NA/Ex-NA Development Costs for each
                           calendar year based on the activities to be conducted
                           under the Global Development Plan;

                  (i)      determining the specific Development activities to be
                           undertaken by each of the Parties with respect to
                           North America Development and NA/Ex-NA Development,
                           subject to the oversight of the Joint Development
                           Committee; and

                  (j)      reviewing on a quarterly basis the NA Development
                           Costs and NA/Ex-NA Development Costs against the
                           budget for such expenses, and making appropriate
                           adjustments to the budgets, all in accordance with
                           Section 3.5.

         3.2.4    DECISION MAKING.

                  (a)      All decisions of the Joint Development Committee and
                           the Joint Development Project Teams relevant solely
                           for the Development of a Joint Development Compound
                           for Commercialization in North America ("North
                           America Development") or relevant for the


                                      Page 44
<PAGE>

                           Development of a Joint Development Compound for
                           Commercialization both in North America and outside
                           of North America ("NA/Ex-NA Development") shall be
                           made by the unanimous decision of Millennium and
                           Aventis, with the representatives of each Party who
                           are members of the Joint Development Committee or the
                           applicable Joint Development Project Team
                           collectively having one vote in any matter requiring
                           the approval of the Joint Development Committee or
                           the applicable Joint Development Project Team.

                  (b)      Aventis shall be entitled to make unilateral
                           decisions on matters relevant solely for the
                           Development of a Joint Development Compound for
                           Commercialization outside of North America ("ROW
                           Development"); provided that such decisions do not
                           conflict with the applicable Global Development Plan.

         3.2.5    DISPUTE RESOLUTION. If a Joint Development Project Team is
                  unable to reach unanimous agreement on any issue within its
                  purview relating to North America Development or NA/Ex-NA
                  Development of a Joint Development Compound, it shall refer
                  such issue to the Joint Development Committee for resolution.
                  If a Joint Development Committee is unable to reach unanimous
                  agreement on any issue within its purview relating to North
                  America Development or NA/Ex-NA Development (including without
                  limitation any issue referred to it by a Joint Development
                  Project Team), such issue shall be resolved in accordance with
                  the provisions of Article 12. Each of the members of each
                  Joint Development Committee shall have experience and
                  seniority sufficient to enable him or her to make decisions on
                  behalf of the Parties.

3.3      DEVELOPMENT ACTIVITIES.

         3.3.1    GENERALLY. All Development of Joint Development Compounds
                  shall be conducted in accordance with the project progression
                  guidelines and criteria established by the Joint Development
                  Committee. The Parties shall use commercially reasonable
                  efforts to conduct the Development activities assigned to them
                  by the Joint Development Project Team in accordance with the
                  Global Development Plan as may be amended from time to time.
                  Furthermore, each Party agrees to conduct such Development
                  activities in compliance with all Laws that are applicable to
                  the particular stage of Development of the Joint Development
                  Compound, including without limitation, GLPs, GCPs and GMPs.



                                      Page 45


<PAGE>


    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         3.3.2    ASSIGNMENT AND RESPONSIBILITY FOR DEVELOPMENT ACTIVITIES. The
                  Joint Development Committee shall oversee the allocation and
                  assignment of Development activities in the Global Development
                  Plans between the Parties with the goal that each Party's
                  participation in North America Development and NA/Ex-NA
                  Development of Joint Development Compounds shall be
                  substantially equal on an ongoing basis, taking into account
                  the levels of participation in prior years and the
                  participation specified in the Global Development Plans for
                  the following calendar year; [**]. Notwithstanding the
                  foregoing, Aventis shall be responsible for the Development
                  activities in the Global Development Plan that relate solely
                  to ROW Development (subject to Joint Development Committee
                  oversight), and Millennium and Aventis shall be jointly
                  responsible for the Development activities in the Global
                  Development Plan that relate to North America Development, as
                  well as those aspects of the Global Development Plan that
                  relate to NA/Ex-NA Development, in each case in a manner
                  consistent with the Global Development Plan. For the purposes
                  of clarity, the allocation of regulatory activities relating
                  to Development of Joint Development Products or Joint
                  Development Compounds shall be governed by Section 5.1.2 and
                  not by this Section.

3.4      JOINT DEVELOPMENT COSTS. NA/Ex-NA Development Costs and NA Development
         Costs for a Joint Development Compound shall be provided for in a
         budget to be included in the Global Development Plan, and shall be
         shared on a Joint Development Compound-by-Joint Development Compound
         basis pursuant to Section 8.2 as follows: (a) Millennium and Aventis
         shall each bear fifty percent (50%) of the NA Development Costs for the
         Joint Development Compound, and (b) Millennium and Aventis shall each
         bear a portion of all NA/Ex-NA Development Costs for the Joint
         Development Compound equal to fifty percent (50%) of the NA Percentage.
         For clarity, Aventis shall also bear a percentage of the NA/Ex-NA
         Development Costs for the Joint Development Compound equal to one
         hundred percent (100%) less the NA Percentage and shall bear one
         hundred percent (100%) of ROW Development costs that are not relevant
         to NA/Ex-NA Development.

3.5      JOINT DEVELOPMENT BUDGET. The budgets set forth in each Global
         Development Plan shall estimate the internal and external costs
         required to complete the Development of the Joint Development Compound,
         broken down by NA Development Costs and NA/Ex-NA Development Costs. The
         budgets for NA Development Cost and NA/Ex-NA Development Cost for the
         current and next succeeding calendar years shall be specified in more
         detail to include, without limitation, on a study-by-study or
         activity-by-activity basis any (i) investigator fees and expert fees,
         (ii) CRO costs, lab fees and scientific service fees, (iii) FTE Cost
         and (iv) Clinical Supply Cost. The budgets shall be updated at least
         once


                                   Page 46
<PAGE>

         annually on a timeline that meets the budget planning requirements of
         both Parties. Each Joint Development Project Team shall review on a
         quarterly basis the NA Development Costs and NA/Ex-NA Development Costs
         against the budget for such expenses in the applicable calendar year.
         If in the course of its quarterly review of NA Development Costs and
         NA/Ex-NA Development Costs, any Joint Development Project Team should
         determine for any Joint Development Compound that for any study or
         activity the actual amounts incurred for (i) investigator fees and
         expert fees, (ii) CRO costs, lab fees and scientific service fees,
         (iii) FTE Cost or (iv) Clinical Supply Cost are likely to be higher
         than budgeted, the Joint Development Project Team shall review the
         reasons for such potential overrun and determine whether such overrun
         is appropriate. If the Joint Development Project Team determines that
         such overrun is appropriate, the Joint Development Project Team will
         assess whether such overrun is likely to result in an overrun of the
         budget for NA Development Costs and NA/Ex-NA Development Costs for such
         Joint Development Compound and if required, will agree on a revised
         budget for NA Development Costs or NA/Ex-NA Development Costs for such
         Joint Development Compound so that no overrun is expected. If the Joint
         Development Project Team determines that such overrun is not
         appropriate, the Joint Development Project Team will take such actions
         as required to remedy the situation.

3.6      DISCONTINUED DEVELOPMENT.

         3.6.1    In the event that the Parties undertake the Development of a
                  Joint Development Compound and thereafter either Party elects
                  not to continue its participation in the Development of such
                  Joint Development Compound, it shall provide written notice to
                  the other Party of such election (a "Notice of
                  Discontinuance").


                                      Page 47
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         3.6.2    Upon receipt of a Notice of Discontinuance, the other Party
                  may, subject to the provisions of Section 3.9, elect to
                  continue the Development of such Joint Development Compound
                  and Pre-EDC Research Evaluation related to its Back-Up
                  Compounds by providing written notice of such election to the
                  other Party within [**] of receipt of the Notice of
                  Discontinuance, in which case such Joint Development Compound
                  shall thereafter be a Unilateral Development Compound (and not
                  a Joint Development Compound).

         3.6.3    In the event that (a) both Parties (i) elect not to continue
                  their participation in the Development of a Joint Development
                  Compound and Pre-EDC Research Evaluation related to its
                  Back-Up Compounds, or (ii) fail to exercise commercially
                  reasonable efforts in undertaking such Development and Pre-EDC
                  Research Evaluation and neither cures such failure within [**]
                  after receipt of written notice from a Party asserting such
                  failure (PROVIDED THAT if the first Party to receive such
                  written notice responds within such [**] period with a
                  notice to the other Party asserting that such other Party has
                  also failed to exercise commercially reasonable efforts in
                  undertaking such Development and Pre-EDC Research Evaluation,
                  both written notices shall, for purposes of this subsection,
                  be deemed to have been given concurrently on the date that the
                  first notice was given), or (b) the Developing Party elects
                  not to continue the Development of a Unilateral Development
                  Compound and Pre-EDC Research Evaluation related to its
                  Back-Up Compounds, or (ii) fails to exercise commercially
                  reasonable efforts in undertaking such Development and Pre-EDC
                  Research Evaluation and does not cure such failure within [**]
                  after receipt of written notice from the other Party asserting
                  such failure, then such compound shall thereafter be a Dropped
                  EDC Compound (and not a Joint Development Compound or a
                  Unilateral Development Compound, as the case may be).

3.7      UNILATERAL DEVELOPMENT.

         3.7.1    GENERAL. A Party undertaking the development of a Unilateral
                  Development Compound (the "Developing Party") shall do so at
                  its own expense and, other than as provided in this Section
                  3.7, independent of the other Party; provided that the
                  Developing Party shall provide the other Party with an annual
                  report concerning the status of the Development of the
                  Unilateral Development Compound. The Parties will cooperate to
                  the extent practicable and at the Developing Party's expense
                  (subject to the provisions of Section 3.7.2) to transition
                  such Joint Development Compound to a Unilateral Development
                  Compound.


                                      Page 48
<PAGE>

         3.7.2    ONGOING STUDIES. With respect to a Unilateral Development
                  Compound that was previously a Joint Development Compound,
                  upon designation of such compound as a Unilateral Development
                  Compound:

                  (a)      CLINICAL STUDIES. With respect to any clinical
                           studies for a Unilateral Development Compound which
                           have been initiated at the time the non-Developing
                           Party provides the Notice of Discontinuance and which
                           were under the responsibility of the non-Developing
                           Party per the Global Development Plan, the
                           non-Developing Party shall complete such studies,
                           with the costs associated with such studies to be
                           shared as if such UDC had continued to be a JDC;
                           provided, however, that in the case in which the
                           Joint Development Compound does not meet its
                           pre-determined criteria for development at a Go/No Go
                           decision point as specified in the Global Development
                           Plan, but the Developing Party nevertheless wishes to
                           continue the Development of the Joint Development
                           Compound as a Unilateral Development Compound, then
                           any such continued activity by the non-Developing
                           Party shall be at the cost and expense of the
                           Developing Party. With respect to any other clinical
                           studies included in the Global Development Plan that
                           were under the responsibility of the non-Developing
                           Party and that were scheduled to be initiated (i.e.,
                           scheduled for enrollment of a patient) in the same
                           calendar year in which the Notice of Discontinuance
                           is provided, the non-Developing Party shall, upon the
                           written request of the Developing Party, initiate
                           such study and transfer the same to the Developing
                           Party as soon as is reasonably practicable, all at
                           the cost and expense of the Developing Party, with
                           such costs to be determined in a manner consistent
                           with the manner in which NA Development Costs and
                           NA/Ex-NA Development Costs are determined. Such
                           transfer shall be conducted in a manner that does not
                           adversely affect the Development of the Unilateral
                           Development Compound (other than in an immaterial
                           manner).

                  (b)      PRE-CLINICAL AND OTHER NON-CLINICAL STUDIES. If the
                           non-Developing Party is conducting any pre-clinical
                           or other non-clinical studies for the Unilateral
                           Development Compound that have been initiated prior
                           to the Notice of Discontinuance, such non-Developing
                           Party shall complete such studies, unless the Parties
                           mutually agree otherwise, with the costs associated
                           with such studies to be shared as if such UDC had
                           continued to be a JDC.


                                      Page 49
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         3.7.3    REGULATORY REQUIREMENTS. The Parties will cooperate to ensure
                  that the Developing Party, at its sole expense, has access to
                  any Regulatory Approvals obtained under the Global Development
                  Plan prior to the Notice of Discontinuance that are relevant
                  to such Unilateral Development Compound as shall be reasonably
                  necessary to enable the Developing Party to continue the
                  Development and Commercialization of such Unilateral
                  Development Compound. Such access shall be provided by license
                  under the applicable Regulatory Approvals, transfer of the
                  applicable Regulatory Approvals, or a letter of reference with
                  respect to the applicable Regulatory Approvals, or such other
                  action as shall be mutually agreed by the Parties.

         3.7.4    INFORMATION TRANSFER. As soon as reasonably practicable, the
                  non-Developing Party will transfer any material, data,
                  information or results obtained in the Development under the
                  Global Development Plan of the Joint Development Compound (as
                  predecessor of the Unilateral Development Compound), and its
                  Back-Up Compounds, to the Developing Party.

         3.7.5    MANUFACTURE OF CLINICAL SUPPLY OF UNILATERAL DEVELOPMENT
                  COMPOUND.

                  (a)      If the non-Developing Party is manufacturing the
                           Unilateral Development Compound, then the Parties
                           will meet to discuss the cooperation to transfer
                           any required manufacturing technology to the
                           Developing Party (or Third Party designee reasonably
                           acceptable to the non-Developing Party), at the
                           Developing Party's expense.

                  (b)      In addition, the non-Developing Party will, for a
                           period not to exceed [**], use commercially
                           reasonable efforts to supply the Developing Party
                           with sufficient quantities of Unilateral Development
                           Compound to enable the Developing Party to continue
                           the Development of the Unilateral Development
                           Compound in accordance with the scope of the Global
                           Development Plan as it existed as of the date of the
                           Notice of Discontinuance; PROVIDED, HOWEVER, nothing
                           contained in this Section shall require the
                           non-Developing Party to increase its scale of
                           manufacturing beyond the scale which existed as of
                           the date of the Notice of Discontinuance.

                  (c)      The non-Developing Party shall supply Unilateral
                           Development Compound to the Developing Party at the
                           Supply Price, plus charges for Relevant Period Costs,
                           and upon such other reasonable and customary terms as
                           to forecasting, shipment, delivery and similar
                           matters as may be agreed.


                                      Page 50
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  3.7.6    RIGHT OF FIRST NEGOTIATION. If, at any time, the
                           Developing Party intends to undertake research,
                           Development or Commercialization activities with
                           respect to a Unilateral Development Compound and/or
                           its Back-Up Compounds in collaboration with a Third
                           Party (or grant a license to a Third Party to do any
                           of the foregoing), the Developing Party shall provide
                           the other Party with the opportunity to negotiate
                           terms under which the other Party would collaborate
                           in or obtain a license for undertaking such
                           activities (a "Compound Right of First Negotiation"),
                           provided that a Compound Right of First Negotiation
                           shall not apply to the retention of a contract sales
                           force or to a product distribution or contract
                           manufacturing arrangement or other outsourced
                           marketing, advertising or promotion activities
                           (unless such arrangement is with a Significant
                           Pharmaceutical Enterprise). A Compound Right of First
                           Negotiation shall operate as follows:

                           (a)      The Developing Party shall promptly notify
                                    the other Party in writing (the "Compound
                                    Notification") of its intention to seek a
                                    collaborator or licensee for the research,
                                    Development and/or Commercialization of the
                                    relevant Unilateral Development Compound
                                    and/or its Back-Up Compounds and shall
                                    provide to the other Party a reasonably
                                    detailed written description of such
                                    proposed collaboration or license, together
                                    with any data, results materials or
                                    information related to such Unilateral
                                    Development Compound and/or its Back-Up
                                    Compounds which has not previously been
                                    provided to the non-Developing Party.

                           (b)      Within [**] of its receipt of the Compound
                                    Notification (the "Compound Response
                                    Period"), the other Party shall notify the
                                    Developing Party of its interest, if any, in
                                    initiating discussions regarding such
                                    proposed collaboration or license.

                           (c)      In the event that the other Party notifies
                                    the Developing Party prior to the
                                    termination of the Compound Response Period
                                    that it has an interest in participating in
                                    such proposed collaboration or in obtaining
                                    such license (a "Compound Expression of
                                    Interest"), then the Parties shall negotiate
                                    in good faith in an effort to reach a
                                    definitive agreement regarding such
                                    collaboration or license for a period of up
                                    to [**] from the date of the Developing
                                    Party's receipt of the Compound Expression
                                    of Interest.


                                      Page 51
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                           (d)      In the event that the Parties reach a
                                    definitive agreement with respect to such
                                    Unilateral Development Compound and/or its
                                    Back-Up Compounds pursuant to subsection
                                    (c), such Unilateral Development Compound
                                    shall no longer be designated a Unilateral
                                    Development Compound and the rights and
                                    obligations of the Parties with respect to
                                    such compound shall be governed by the terms
                                    of such definitive agreement and not this
                                    Agreement.

                           (e)      In the event that (i) the other Party fails
                                    to notify the Developing Party prior to the
                                    termination of the Compound Response Period
                                    that it is interested in collaborating or
                                    obtaining a license with the Developing
                                    Party with respect to such Unilateral
                                    Development Compound and/or its Back-Up
                                    Compounds, or (ii) the other Party notifies
                                    the Developing Party prior to the
                                    termination of the Compound Response Period
                                    that it has no interest in such
                                    collaboration or license, or (iii) the other
                                    Party timely provides the Developing Party
                                    with a Compound Expression of Interest but
                                    the Parties fail to reach a definitive
                                    agreement within the [**] period specified
                                    in subsection (c), then the Developing Party
                                    shall be free to enter into a collaboration
                                    or license with a Third Party with respect
                                    to such Unilateral Development Compound
                                    and/or its Back-Up Compounds; PROVIDED,
                                    HOWEVER, that the Developing Party may not
                                    enter into any collaboration or license with
                                    a Third Party on terms which are more
                                    favorable to the Third Party, taken as a
                                    whole, than those last offered to the
                                    non-Developing Party.

                           (f)      For the duration of the Compound Response
                                    Period, and if the other Party timely
                                    delivers the Compound Expression of
                                    Interest, the [**] term specified in Section
                                    3.7.6(c), the Developing Party may discuss
                                    with a Third Party the general outline of
                                    such collaboration or license; provided,
                                    however, that the Developing Party shall not
                                    negotiate such collaboration with a Third
                                    Party, enter into any agreements with such
                                    Third Party or propose terms to such Third
                                    Party on which the Developing Party would be
                                    willing to consummate such collaboration or
                                    license.


                                      Page 52
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

3.8      DROPPED EDC COMPOUND.

         3.8.1    Subject to the provisions of Section 3.9, either Party shall
                  have the right to elect to re-initiate Development activities
                  with respect to a Dropped EDC Compound and Pre-EDC Research
                  Evaluation related to its Back-Up Compounds; PROVIDED THAT
                  such Party first gives notice of its intent to re-initiate
                  Development activities to the other Party, and provides the
                  other Party with any data, results, materials or information
                  related to such Dropped EDC Compound and its Back-Up Compounds
                  which was not previously provided to the other Party.

         3.8.2    If the other Party acknowledges that it does not at such time
                  desire to participate in the Development of such Dropped EDC
                  Compound and Pre-EDC Research Evaluation related to its
                  Back-Up Compounds, the electing Party may resume Development
                  of such compound and such compound shall thereafter be a
                  Unilateral Development Compound (and not a Dropped EDC
                  Compound or a Joint Development Compound) and its Development
                  shall be governed by the provisions set forth in Section 3.7.

         3.8.3    If the other Party desires to participate in the Development
                  of such Dropped EDC Compound and Pre-EDC Research Evaluation
                  related to its Back-Up Compounds, and so notifies the electing
                  Party within [**] of receipt of notice from the notifying
                  Party, such compound shall thereafter be a Joint Development
                  Compound (and not a Dropped EDC Compound or a Unilateral
                  Development Compound) for the purposes of this Agreement.

3.9      BACK-UP COMPOUNDS

         3.9.1    When a Program Compound is nominated for EDC Status, the EDC
                  Data Package shall identify other Program Compounds which
                  shall serve as "Back-Up Compounds". Back-Up Compounds shall be
                  identified by the Joint Research Committee based on back-up
                  selection criteria agreed upon by the Joint Research Committee
                  pursuant to 2.4.1.

         3.9.2    Notwithstanding anything contained in this Agreement to the
                  contrary, neither Party shall have the right to Develop as a
                  Unilateral Development Compound any Back-Up Compound if the
                  Parties are Developing or Commercializing one or more Joint
                  Development Compounds or Joint Development Products which are
                  Active against the same Program Target as such Back-Up
                  Compound. In addition, neither Party may unilaterally Develop
                  a Back-Up Compound [**] as an EDC Compound which is being
                  Developed unilaterally by the other Party and which is Active
                  against the same Program Target.


                                      Page 53
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         3.9.3    The selection of an EDC Compound as a Joint Development
                  Compound or Unilateral Development Compound shall include
                  Back-Up Compounds.

3.10     RIGHT TO AUDIT. Each Party shall ensure that the other Party's
         authorized representatives, and regulatory authorities to the extent
         permitted by Law, may, during regular business hours, (a) examine and
         inspect the facilities of any subcontractor or any investigator site
         used in the performance of North America Development or NA/Ex NA
         Development involving a Joint Development Compound, and (b) inspect and
         copy all data, documentation and work products relating to the
         activities performed by the subcontractor or investigator site,
         including, without limitation, the medical records of any patient
         participating in any clinical study. A Party's right to inspect and
         copy all data, documentation, and work products relating to a Joint
         Development Compound study included in North America Development or
         NA/Ex-NA Development shall survive the completion of the study for a
         period of [**] after the study is completed, or such longer period as
         shall be required by Law.

3.11     USE OF SUBCONTRACTORS. To the extent either Party wishes to perform
         some of its obligations regarding the Development of Joint Development
         Compounds in North America Development or NA/Ex-NA Development,
         including without limitation any activities under Article 5, through
         one or more subcontractors, it must obtain the written approval of the
         other Party prior to engaging such subcontractor, which approval shall
         not be unreasonably withheld or delayed. As a condition to granting
         such approval, (a) the other Party shall be entitled to audit the
         proposed subcontractor using the same standards which it applies to the
         use of subcontractors in the Development of its other products, and (b)
         the subcontractor must undertake in writing obligations of
         confidentiality and non-use regarding the other Party's Confidential
         Information which are substantially the same as those undertaken by
         Aventis or Millennium pursuant to Article 9 hereof. In the event a
         Party performs one or more of its obligations regarding the North
         America Development or NA/Ex NA Development of a Joint Development
         Compound through the use of a subcontractor, then such Party shall at
         all times be responsible for the performance of such subcontractor. For
         the avoidance of doubt, it is understood that an Affiliate of a Party
         shall not be deemed to be a subcontractor of such Party. For clarity,
         it is understood that the provisions of this Section 3.11 do not apply
         to contracts with individual clinical sites and other contractual
         arrangements of a similarly small financial magnitude.

3.12     PHARMACOVIGILANCE. No later than initiation of the first toxicology
         studies for a Joint Development Compound, the pharmacovigilance
         departments of both Parties shall meet and determine the approach to be
         taken for the collection, review, assessment, tracking and filing of
         information related to adverse events associated with the Joint
         Development Compound.


                                      Page 54
<PAGE>


                                   ARTICLE 4

                             MANUFACTURE AND SUPPLY

4.1      CLINICAL SUPPLY. As part of the first Global Development Plan for each
         Joint Development Compound, the Joint Development Committee shall
         specify which Party shall be responsible for manufacturing quantities
         of such compound for use in pre-clinical and clinical trials. It is
         expected that only one Party shall be responsible for manufacturing all
         quantities of a Joint Development Compound and the related Joint
         Development Product necessary for pre-clinical and clinical studies
         throughout the Territory.

4.2      COMMERCIAL SUPPLY. As part of the first Global Commercialization Plan
         for each Joint Development Product, the Joint Commercialization
         Committee shall specify which Party shall be responsible for
         manufacturing the Joint Development Compound (as the active ingredient)
         and Joint Development Product for commercial sale, as described in
         Schedule 4.2 It is expected that only one Party shall be responsible
         for manufacturing all necessary quantities of a Joint Development
         Compound and the related Joint Development Product for commercial sale
         throughout the Territory.

4.3      SUPPLY AGREEMENT. In the case where Millennium is responsible for
         manufacturing a Joint Development Compound and/or Joint Development
         Product or in the case where Aventis is responsible for manufacturing a
         Joint Development Compound and/or a Joint Development Product and
         Millennium is responsible for clinical studies, Development activities
         for the Joint Development Compound or distributing the Joint
         Development Product in North America, the Parties shall enter into a
         clinical supply agreement or commercial supply agreement, as
         applicable, on customary and reasonable terms and conditions. Each such
         supply agreement shall provide, among other things, for pricing at the
         manufacturing Party Supply Price, plus charges for Relevant Period
         Costs, forecasting and ordering requirements, inventory maintenance
         requirements, and for manufacturing in compliance with applicable
         regulatory requirements, and shall meet the guidelines of both
         Millennium and Aventis.

4.4      USE OF SUBCONTRACTORS. To the extent either Party wishes to perform
         some of its obligations regarding the manufacturing and supply of Joint
         Development Compounds and/or Joint Development Products for North
         America through one or more subcontractors, it must obtain the written
         approval of the other Party prior to engaging such subcontractor, which
         approval shall not be unreasonably withheld or delayed. It is
         understood that as a condition to granting such approval, (a) the other
         Party shall be entitled to audit the proposed subcontractor using the
         same standards which it applies to the use of subcontractors in the
         manufacturing of its other products, (b) the subcontractor must
         undertake in writing obligations of confidentiality and non-use
         regarding the other Party's Confidential Information which are
         substantially the same as those undertaken by Aventis or Millennium
         pursuant to Article 9 hereof, and (c) the other Party shall have


                                      Page 55
<PAGE>


         the right to approve any of the financial terms of the arrangement
         which affect the Supply Price. In the event a Party performs one or
         more of its obligations regarding the manufacturing and supply of a
         Joint Development Compound or a Joint Development Product for North
         America through the use of a subcontractor, then such Party shall at
         all times be responsible for the performance of such subcontractor. For
         the avoidance of doubt, it is understood that an Affiliate of a Party
         shall not be deemed to be a subcontractor of such Party.

                                   ARTICLE 5

                               REGULATORY MATTERS.

5.1      OWNERSHIP.

         5.1.1    The Joint Development Committee shall identify the Party which
                  shall own in North America the INDs for each Joint Development
                  Compound and the NDAs for each Joint Development Product (the
                  "Lead Regulatory Party") in accordance with Section 3.3.2. The
                  Lead Regulatory Party shall license, transfer, provide a
                  letter of reference with respect to, or take other action
                  necessary to make available such INDs or NDAs to the other
                  Party as may be reasonably necessary to enable such other
                  Party to fulfill its obligations under the Global Development
                  Plan with respect to the Development of such Joint Development
                  Compound and under the Global Commercialization Plan with
                  respect to the Commercialization of such Joint Development
                  Product.

         5.1.2    Subject to Section 3.3.2, it is the intention of the Parties
                  that ownership of Regulatory Approvals in North America
                  relating to Joint Development Products shall be divided
                  equally between the Parties on an ongoing basis, taking into
                  account Regulatory Approvals relating to Joint Development
                  Products that are currently owned by each of the Parties, as
                  well as additional Regulatory Approvals in North America
                  relating to Joint Development Products to be allocated to the
                  Parties in the following calendar year. Aventis shall hold all
                  Regulatory Approvals for Joint Development Compounds and Joint
                  Development Products for all countries outside of North
                  America, unless otherwise determined by the Joint Development
                  Committee.

         5.1.3    To the extent that the Joint Development Committee assigns
                  Development activities to Millennium to be conducted outside
                  of North America, Aventis shall take such action as may be
                  reasonably necessary to permit such activities to be performed
                  under Aventis' Regulatory Approvals in such country.


                                      Page 56
<PAGE>

5.2      REGULATORY COORDINATION.

         5.2.1    The Lead Regulatory Party shall oversee, monitor and
                  coordinate all regulatory actions, communications and filings
                  with and submissions, including filings and submissions of
                  supplements and amendments thereto, to the FDA or HPB with
                  respect to the relevant Joint Development Compound or Joint
                  Development Product. Aventis shall oversee, monitor and
                  coordinate all regulatory actions, communications and filings
                  with and submissions to, including filings and submissions of
                  supplements and amendments thereto, regulatory authorities
                  outside of North America with respect to the relevant Joint
                  Development Compound or Joint Development Product unless
                  otherwise determined by the Joint Development Committee.

         5.2.2    In the event that Millennium is the Lead Regulatory Party, the
                  Parties shall establish procedures to ensure that the Parties
                  exchange on a timely basis all necessary information to enable
                  compliance with all regulatory obligations on a global basis,
                  including without limitation filing updates, pharmacovigilance
                  filings and investigator notifications.

5.3      REGULATORY MEETINGS AND CORRESPONDENCE. The Lead Regulatory Party shall
         be responsible for interfacing, corresponding and meeting with the FDA
         and HPB with respect to the relevant Joint Development Compound or
         Joint Development Product. To the extent practicable, the other Party
         shall have the right to have a representative participate in all
         material meetings and telephone discussions between representatives of
         the Lead Regulatory Party and the FDA or HPB with respect to such Joint
         Development Compound or Joint Development Product. Aventis shall be
         responsible for interfacing, corresponding and meeting with regulatory
         authorities outside of North America with respect to all Joint
         Development Compounds and Joint Development Products unless otherwise
         determined by the Joint Development Committee.

5.4      REVIEW OF CORRESPONDENCE. To the extent practicable, the Lead
         Regulatory Party shall provide the other Party with drafts of any
         documents or other correspondence to be submitted to the FDA or HPB
         pertaining to the relevant Joint Development Compound or Joint
         Development Product, sufficiently in advance of submission so that the
         other Party may review and comment on such documents and other
         correspondence and have a reasonable opportunity to influence the
         substance of such submissions. The Lead Regulatory Party shall promptly
         provide to the other Party copies of any documents or other
         correspondence received from the FDA and HPB pertaining to the relevant
         Joint Development Compound or Joint Development Product (including
         without limitation any meeting minutes). To the extent relevant to the
         Development of a Joint Development Compound for North America, Aventis
         shall, subject to applicable Laws, provide Millennium with drafts of
         any documents or other correspondence to be submitted to regulatory
         authorities outside of North America pertaining to the relevant Joint
         Development Compound or Joint


                                      Page 57
<PAGE>

         Development Product, sufficiently in advance of submission so that
         Millennium may review and comment on such documents and other
         correspondence and have a reasonable opportunity to influence the
         substance of such submissions, as it may affect the Development of such
         Joint Development Compound for North America. Aventis agrees to
         consider all such comments in good faith, taking into account the best
         interest of the Joint Development Compound on a global basis. If after
         considering in good faith Millennium's comments regarding the content
         of a proposed submission to a regulatory authority outside of North
         America, Aventis disagrees with Millennium's view, Aventis shall notify
         Millennium in writing (a "Notice of Disagreement"). If Millennium
         believes that Aventis' proposed submission is likely to have a material
         adverse effect on the Development of the Joint Development Product on a
         global basis, it shall so notify Aventis, and provided that such
         notification is delivered to Aventis within three (3) business days
         following receipt of Aventis' Notice of Disagreement, Millennium shall
         have the right to request that the Joint Development Committee
         immediately convene, either in person or by telephone, in order to
         discuss the matter. Any such meeting shall occur within three (3)
         business days following Millennium's request. If after the discussions
         of the Joint Development Committee Aventis still disagrees with
         Millennium's view regarding the proposed submission, Aventis has the
         right to file such submission as it reasonably deems appropriate;
         provided, however, that any such submission shall not be inconsistent
         with the best interest of the Joint Development Product on a global
         basis, and shall not be inconsistent with the Global Development Plan.
         To the extent relevant to the Development of a Joint Development
         Compound for North America, Aventis shall promptly provide to
         Millennium copies of any documents or other correspondence received
         from regulatory authorities outside of North America pertaining to the
         relevant Joint Development Compound or Joint Development Product.

5.5      ASSISTANCE.

         5.5.1    Each Party shall cooperate with the other Party to provide all
                  reasonable assistance and take all actions reasonably
                  requested by the other Party that are necessary or desirable
                  to enable the other Party to comply with any Law applicable to
                  any Joint Development Product, including, but not limited to,
                  report adverse drug experience reports (and serious adverse
                  drug experience reports) to the FDA or other governmental or
                  regulatory authorities and submit or file North America
                  promotional materials with the FDA.


                                      Page 58
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         5.5.2    Such assistance and actions shall include, among other things,
                  keeping the other Party informed, commencing within [**] of
                  notification of any action by, or notification or other
                  information which it receives (directly or indirectly) from,
                  the FDA or any other governmental or regulatory authority,
                  which (a) raises any material concerns regarding the safety or
                  efficacy of any Joint Development Product, (b) which indicates
                  or suggests a potential material liability for either Party to
                  Third Parties arising in connection with any Joint Development
                  Product, or (c) which is reasonably likely to lead to a recall
                  or market withdrawal of any Joint Development Product,
                  provided that neither Party shall be obliged to disclose
                  information in breach of any contractual restriction which it
                  could not reasonably have avoided. Information that shall be
                  disclosed pursuant to this Section 5.5.2 shall include, but
                  not be limited to:

                  (a)      governmental or regulatory inspections of
                           manufacturing, distribution or other related
                           facilities used for Joint Development Compounds or
                           Joint Development Products;

                  (b)      inquiries by governmental or regulatory authorities
                           concerning clinical investigation activities
                           (including inquiries of investigators, clinical
                           monitoring organizations and other related parties)
                           relating to Joint Development Compounds or Joint
                           Development Products;

                  (c)      any communication from governmental or regulatory
                           authorities pertaining to the manufacture, sale,
                           promotion or distribution of Joint Development
                           Compounds or Joint Development Products;

                  (d)      any other governmental or regulatory authority
                           reviews or inquiries relating to Joint Development
                           Compounds or Joint Development Products;

                  (e)      receipt of a warning letter relating to any of the
                           Joint Development Compounds or Joint Development
                           Products; and

                  (f)      an initiation of any governmental or regulatory
                           authority investigation, detention, seizure or
                           injunction concerning any Joint Development Compound
                           or Joint Development Product.


                                      Page 59
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         5.5.3    Each Party shall provide (i) notice of patents relevant to an
                  NDA, prior to the time the NDA is filed, and (ii) immediate
                  notice of the issuance of any patent which will be a patent
                  relevant to a Joint Development Product, giving the date of
                  issue and patent number for each such patent and the Parties
                  will jointly decide within [**] of the patent issue if the
                  patent is to be listed pursuant to any NDA submission for such
                  Joint Development Product. Similarly, the Parties shall
                  provide immediate notice of any approved NDA and of patent
                  term extensions in any country. The Parties will cooperate
                  with each other in the preparation and filing of patent
                  listings and patent term extensions, and in mutually deciding
                  whether one, or both Parties will proceed in filing of
                  appropriate listing and patent term extension documents. Each
                  Party will provide prompt notice to the other of any inquiries
                  as to any relevant patent which has claims to manufacturing
                  processes, which inquiries are provided pursuant to 35 USC
                  Section 271(g), and will cooperate with respect to responses
                  thereto.

ARTICLE 6

                            COMMERCIALIZATION PROGRAM

6.1      OBJECTIVES FOR COMMERCIALIZATION OF JOINT DEVELOPMENT PRODUCTS.

         6.1.1    The Joint Commercialization Committee shall oversee the
                  allocation of North America Commercialization and NA/Ex-NA
                  Commercialization strategic activities (i.e., responsibility
                  for promotion, distribution, detailing, marketing) between the
                  Parties for Joint Development Products with the goal that each
                  Party's participation in North America Commercialization and
                  NA/Ex-NA Commercialization of Joint Development Products in
                  North America shall, to the extent practicable, be
                  substantially equal on an ongoing basis, taking into account
                  the levels of participation in prior years and the
                  participation specified in the North America Commercialization
                  Plans and/or Global Commercialization Plans for the following
                  calendar year, PROVIDED THAT a Party shall not be assigned a
                  particular Commercialization activity or responsibility unless
                  it has the capacity and capability to undertake such activity
                  or responsibility, as determined by the Joint
                  Commercialization Committee.

         6.1.2    Aventis will have the sole discretion and exclusive right to
                  promote, sell and distribute Joint Development Products in the
                  ROW, so long as such activities are not inconsistent with the
                  Global Commercialization Plan.


                                      Page 60
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         6.1.3    Without limiting the provisions of Section 6.1.2, Aventis
                  shall have sole discretion and primary responsibility for the
                  implementation of those elements of the Global
                  Commercialization Plan that are solely related to ROW
                  Commercialization (subject to Joint Commercialization
                  Committee oversight) and Millennium and Aventis shall be
                  jointly responsible for implementation of those elements of
                  the Global Commercialization Plan that relate to North America
                  Commercialization and NA/Ex-NA Commercialization, in each
                  case, in a manner consistent with the Global Commercialization
                  Plan. NA/Ex-NA Commercialization means activities relating to
                  the Commercialization of a Joint Development Product which are
                  primarily global in nature (e.g., sponsoring international
                  symposia, publications in international medical journals and
                  any global Commercial Phase IIIB Studies, Phase IV Studies and
                  investigator-initiated studies). For clarity, NA/Ex-NA
                  Commercialization is not intended to include activities which
                  are primarily directed outside of North America but which may
                  affect North America (e.g., product promotion in ROW). As used
                  herein, the term "North America Commercialization" or "NA
                  Commercialization" means all activities solely relating to the
                  Commercialization of a Joint Development Product in North
                  America.

6.2      JOINT COMMERCIALIZATION COMMITTEE AND PROJECT TEAMS.

         6.2.1    FORMATION. As soon as reasonably practicable and in any event
                  not later than [**] after the initiation of the first Phase
                  IIA Study for any Joint Development Compound, Aventis and
                  Millennium shall establish a Joint Commercialization Committee
                  to oversee the Commercialization of all Joint Development
                  Products under this Agreement. As soon as practicable
                  following the initiation of the first Phase IIA study for each
                  Joint Development Compound, the Joint Commercialization
                  Committee shall establish a Joint Commercialization Project
                  Team for such Joint Development Compound and related Joint
                  Development Product. The Joint Commercialization Committee
                  shall consist of an appropriate number of Millennium and
                  Aventis representatives, with each Party having one vote, and
                  shall include at least one medical representative from each
                  Party. Each Joint Commercialization Project Team shall be
                  comprised of an appropriate number of representatives from
                  each Party, as may be designated by the Joint
                  Commercialization Committee, with each Party having one vote.

         6.2.2    SUBCOMMITTEES. The Joint Commercialization Committee and each
                  Joint Commercialization Project Team shall act directly or
                  through such working groups or sub-committees as it may deem
                  appropriate to establish. In particular, the applicable North
                  America Commercialization Project Team shall be responsible
                  for matters that relate to North America


                                      Page 61
<PAGE>

                  Commercialization. Each Joint Commercialization Project Team
                  and any subcommittees will be structured and operated in the
                  same manner as the Joint Commercialization Committee,
                  including without limitation, in decision making.

         6.2.3    QUALIFICATIONS. Each of the members of the Joint
                  Commercialization Committee and each Joint Commercialization
                  Project Team shall have experience and seniority sufficient to
                  enable him or her to make decisions on behalf of the Parties.

6.3      JOINT COMMERCIALIZATION COMMITTEE RESPONSIBILITIES. To the extent
         permitted by applicable Law, the Joint Commercialization Committee will
         oversee the global Commercialization of all Joint Development Products
         that are identified for launch in North America, including, among other
         things:

         6.3.1    maintaining global oversight of the Commercialization process;

         6.3.2    providing a forum for consensual decision making;

         6.3.3    reviewing and approving recommendations from and advising the
                  Joint Commercialization Project Teams;

         6.3.4    reviewing and approving the Global Commercialization Plan for
                  each Joint Development Product which shall address the items
                  outlined in Schedule 6.4.4 (the "Global Commercialization
                  Plan") and reflect the objectives of Section 6.1.1;

         6.3.5    reviewing, at its option, market research plans and research
                  results, product development data and results and similar
                  information related to Commercialization of each Joint
                  Development Product in North America;

         6.3.6    monitoring the Parties' compliance with the requirements of
                  the Global Commercialization Plan's NA/Ex-NA Commercialization
                  Budget;

         6.3.7    establishing procedures regarding the collection, sharing and
                  reporting of adverse event information related to each Joint
                  Development Product on a global basis; and

         6.3.8    monitoring the allocation of North America Commercialization
                  and NA/Ex-NA Commercialization strategic activities between
                  the Parties across all of the Joint Development Products to
                  ensure that such allocation is consistent with the provisions
                  of Section 6.1.

6.4      JOINT COMMERCIALIZATION PROJECT TEAM RESPONSIBILITIES. To the extent
         permitted by applicable Law, the Joint Commercialization Project Teams
         will establish the global strategy and oversee the global
         Commercialization for a specific Joint Development Product that is
         identified for launch in North America, including, among other things:


                                      Page 62
<PAGE>

         6.4.1    defining the initial customer group or target group to be
                  covered, including without limitation, the identification and
                  promotional targeting of key opinion leaders, physician
                  groups, hospitals and regional buying groups, including
                  managed care organizations and governmental and
                  government-affiliated buyers;

         6.4.2    forming the North America Commercialization Project Teams;

         6.4.3    making recommendations to the Joint Commercialization
                  Committee regarding the manufacturing and supply chain
                  strategy for the Joint Development Compound (as active
                  ingredient) and the Joint Development Product, including
                  without limitation which Party (or a Third Party) shall be
                  responsible for specific activities in the supply chain;

         6.4.4    preparing the Global Commercialization Plan for the Joint
                  Development Product reflecting the objectives of Section 6.1.1
                  and the items identified in the content outline of the Global
                  Commercialization Plan attached hereto as Schedule 6.4.4, as
                  well as updating the Global Commercialization Plan on an
                  annual basis to reflect materially changed circumstances;

         6.4.5    reviewing and making recommendations to the Joint Development
                  Project Team regarding changes to the target product profile;

         6.4.6    preparing and approving the budget for NA/Ex-NA
                  Commercialization Expense and NA/Ex-NA License Fees based on
                  the NA/Ex NA Commercialization activities set forth in the
                  Global Commercialization Plan (the "NA/Ex-NA Commercialization
                  Budget"), and submitting the same to the Joint
                  Commercialization Committee for its review (but not approval);

         6.4.7    determining the specific Commercialization activities to be
                  undertaken by the Parties relating to NA/Ex-NA
                  Commercialization, subject to the oversight of the Joint
                  Commercialization Committee;

         6.4.8    reviewing on a quarterly basis the NA/Ex-NA Commercialization
                  Expense and NA/Ex-NA License Fees against the budget for such
                  expenses in the applicable calendar year, and making
                  appropriate adjustments to the budgets, all in accordance with
                  Section 6.9.3;

         6.4.9    reviewing the North American Commercialization Plans to ensure
                  that such plans are consistent with the Global
                  Commercialization Plans; and

         6.4.10   in consultation with the North America Commercialization
                  Project Team, reviewing and approving the selection of
                  trademarks for Joint Development Products.


                                      Page 63
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

6.5      DECISION MAKING.

         6.5.1    Subject to Sections 6.5.2 and 6.7, all decisions of each Joint
                  Commercialization Committee and each Joint Commercialization
                  Project Team related to the North America Commercialization
                  and NA/Ex-NA Commercialization of a Joint Development Product
                  shall, to the extent permitted by applicable Law, be made by
                  the unanimous decision of Millennium and Aventis and shall not
                  be inconsistent with the Global Commercialization Plan;
                  PROVIDED HOWEVER, for clarity, Aventis shall have the sole
                  discretion in any decision that is relevant solely to the
                  Commercialization of a Joint Development Product outside of
                  North America ("ROW Commercialization"), as long as such
                  decision is not inconsistent with the Global Commercialization
                  Plan.

         6.5.2    The objective of the Joint Commercialization Committee and
                  each Joint Commercialization Project Team shall be to reach
                  agreement by consensus on all matters falling within its
                  authority hereunder with the goal of realizing the best
                  overall commercial potential of Joint Development Products on
                  a global basis. In the event that the Joint Commercialization
                  Committee or any Joint Commercialization Project Team is
                  unable to reach a unanimous decision with respect to any
                  proposed action requiring its vote, [**]; provided, however,
                  [**] pursuant to this Section 6.5.2 to determine which Party
                  shall perform a particular Commercialization activity or
                  whether Millennium has the capability or capacity to perform a
                  particular Commercialization activity.

         6.5.3    All decisions [**] pursuant to Section 6.5.2 shall be made:

                  (a)      only after referral of the matter [**]; PROVIDED,
                           HOWEVER, [**], as may be reasonably required, to meet
                           deadlines imposed by Third Parties (e.g., deadlines
                           for responses imposed by regulatory authorities) or
                           as otherwise needed to respond to competition in the
                           market. For clarity, [**] to decide the matter, then
                           [**] to decide the matter;

                  (b)      with the goal of realizing the best overall
                           commercial potential of Joint Development Products on
                           a global basis;

                  (c)      in a manner [**] relative [**] in any significant
                           respect; and

                  (d)      in a manner that [**] in the quarterly determination
                           and reconciliation under Section 8.2.2 of actual
                           financial results, including without limitation Net
                           Sales, NA/Ex-NA Expense, NA Development Costs, NA
                           Commercialization Expense and Pre-tax Profit or Loss.
                           For clarity, nothing in this subsection (d) shall
                           [**] make the final determination [**] .


                                      Page 64
<PAGE>

6.6      NORTH AMERICA COMMERCIALIZATION PROJECT TEAM.

         6.6.1    ROLE OF NORTH AMERICA COMMERCIALIZATION PROJECT TEAM. To the
                  extent permitted by applicable Law, the North America
                  Commercialization Project Team shall, among other things,


                  (a)      prepare and approve the North America
                           Commercialization Plan, such plan to be consistent
                           with the Global Commercialization Plan;

                  (b)      develop and discuss strategies for the
                           Commercialization of the Joint Development Product in
                           North America, including (i) contracting strategies
                           and procedures and (ii) the annual North America
                           marketing and promotion activities, detailing
                           activities and sampling strategies;

                  (c)      preparing and approving the budget for NA
                           Commercialization Expense and NA License Fees based
                           on the North America Commercialization Plan (the
                           "North America Commercialization Budget");

                  (d)      review on a quarterly basis progress of (i) the
                           current North America Commercialization Plan, (ii) NA
                           Commercialization Expense and NA License Fees in each
                           calendar year against the budget for such expenses in
                           the applicable calendar year (in accordance with the
                           provisions of Section 6.9.4), (iii) Joint Development
                           Product sales in North America against the forecast
                           included in the current North America
                           Commercialization Plan and (iv) any Commercial Phase
                           IIIB Studies, Phase IV Studies and
                           investigator-initiated studies conducted in
                           connection with North America Commercialization;

                  (e)      determining the specific Commercialization activities
                           to be undertaken by the Parties relating to NA
                           Commercialization, subject to the oversight of the
                           Joint Commercialization Committee; and

                  (f)      in consultation with the Joint Commercialization
                           Project Team, reviewing and approving the selection
                           of the trademarks for Joint Development Products.

         6.6.2    NORTH AMERICA COMMERCIALIZATION PLANS. Each North America
                  Commercialization Plan shall be reviewed by the Joint
                  Commercialization Project Team to ensure consistency with the
                  Global Commercialization Plan and shall stipulate the way in
                  which the Joint Development Product is to be marketed,
                  promoted and detailed in North America during the applicable
                  calendar year to which the plan relates and shall include,
                  inter alia: (a) the number, type and position of Details to be
                  performed and strategies relating to such detailing activity,
                  (b) contracting


                                      Page 65
<PAGE>

                  strategies and procedures to be followed by the Parties
                  relating to North America Commercialization, (c) other
                  advertising and promotional activity to be undertaken in North
                  America, and the Party responsible for undertaking such
                  activities, (d) any training or sampling programs to be
                  conducted in North America, (e) disease management programs to
                  be conducted in North America, (f) medical education programs
                  to be conducted in North America, (g) public relations
                  activities to be conducted in North America and (h) such other
                  activities as may be requested by the Joint Commercialization
                  Project Team to be performed by the North America
                  Commercialization Project Team. The North America
                  Commercialization Plan shall not address sales force
                  incentives or compensation, and each Party shall have sole
                  authority and responsibility for designing and executing any
                  such program for its sales force.

         6.6.3    REVIEW AND APPROVAL OF PROMOTIONAL MATERIALS.

                  (a)      The North America Commercialization Project Team
                           shall be responsible for creating and developing
                           advertising, promotional, educational and
                           communication materials for marketing, advertising
                           and promotion of the Joint Development Products in
                           North America which are intended for distribution to
                           Third Parties (including medical professionals) and
                           to the Parties' respective sales forces in accordance
                           with the terms of the North America Commercialization
                           Plan (the "North America Promotional Materials"),
                           provided, however, it is understood that all North
                           America Promotional Materials shall be consistent
                           with the Global Commercialization Plan and any core
                           promotional materials prepared by the Joint
                           Commercialization Project Team. The North America
                           Commercialization Project Team shall be responsible
                           for establishing procedures for the review and
                           approval of North America Promotional Materials. All
                           product labeling for Joint Development Products in
                           North America shall, to the extent permitted by law,
                           contain equally prominent references to both Aventis
                           and Millennium.

                  (b)      The Parties shall jointly own (without any duty to
                           account to the other) all copyrights in and to any
                           North America Promotional Materials which are
                           specifically directed to the Joint Development
                           Products and each Party shall execute all documents
                           and take all actions as are reasonably requested by
                           the other Party to effectuate such joint ownership in
                           such North America Promotional Materials.


                                      Page 66
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      Neither Party shall produce (other than as concepts
                           for consideration by the North America
                           Commercialization Project Team), distribute or
                           otherwise use in North America any promotional or
                           communications material or any label or labeling
                           relating to the Joint Development Products which has
                           not been approved in accordance with the procedures
                           established by the North America Commercialization
                           Project Team pursuant to this Section 6.6.3.

         6.6.4    ADDITIONAL ACTIVITIES OF THE NORTH AMERICA COMMERCIALIZATION
                  PROJECT TEAM. In addition, the North America Commercialization
                  Project Team shall have the additional role of establishing
                  procedures for: handling of any recalls or customer complaints
                  with respect to Joint Development Products in North America;
                  and responding to medical inquiries regarding the Joint
                  Development Products in North America.

         6.6.5    NORTH AMERICA COMMERCIALIZATION PROJECT TEAM DECISION MAKING.
                  Subject to Sections 6.6.6 and 6.7, all decisions of each North
                  America Commercialization Project Team shall, to the extent
                  permitted by applicable Law, be made by the unanimous decision
                  of Aventis and Millennium and shall not be inconsistent with
                  the Global Commercialization Plan. The objective of each North
                  America Commercialization Project Team shall be to reach
                  consensus on all matters falling within its authority
                  hereunder with the goal of realizing the best overall
                  commercial potential of the applicable Joint Development
                  Product on a global basis. In the event that a North America
                  Commercialization Team is unable to reach a unanimous decision
                  with respect to any proposed action requiring its vote, the
                  issue shall be referred for resolution to the senior executive
                  of each Party responsible for North America (or his or her
                  designee). If such senior executives are unable to resolve
                  such matter within [**] after referral of such matter, Aventis
                  shall have the right to decide the matter, subject to the
                  provisions of Section 6.6.6. Notwithstanding the foregoing,
                  Aventis shall not be entitled to exercise its casting vote
                  pursuant to this Section 6.6.5 to determine which Party shall
                  perform a particular Commercialization activity or whether
                  Millennium has the capability or capacity to perform a
                  particular Commercialization Activity in North America.

         6.6.6    All decisions by Aventis pursuant to Section 6.6.5 shall be
                  made:


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (a)      only after referral of the matter to the Executive
                           Officers as provided in Section 12.3; provided,
                           however, the dispute resolution process shall be
                           accelerated, as may be reasonably required, to meet
                           deadlines imposed by Third Parties or as otherwise
                           needed to respond to competition in the market. For
                           clarity, if the Executive Officers are unable to
                           decide the matter, then Aventis shall have the right
                           to decide the matter;

                  (b)      with the goal of realizing the best overall
                           commercial potential of Joint Development Products on
                           a global basis; and

                  (c)      in a manner that does not solely disadvantage
                           Millennium relative to Aventis in any significant
                           respect.

6.7      COMMERCIALIZATION STRATEGY AND DECISION MAKING. Notwithstanding
         anything to the contrary in this Article 6, in the event that the
         Parties are precluded by applicable Law from jointly establishing
         Commercialization strategy or making Commercialization decisions
         pursuant to Article 6 and relating to a Joint Development Product in
         any country in North America or ROW, then [**] such decisions, PROVIDED
         THAT such establishment of strategy and decision-making shall be
         subject to the provisions of Section 6.5.3(b), (c) and (d) and made in
         a manner that preserves the intent of Section 6.8.

6.8      REVENUE BOOKING IN NORTH AMERICA. To the extent permissible under
         applicable Law, the Parties shall cooperate to coordinate the
         Commercialization activities through the Joint Commercialization
         Committee so that, throughout the course of North America
         Commercialization of Joint Development Products, each Party has an
         opportunity to distribute, and book revenue for, Joint Development
         Products in North America accounting for approximately [**] of all the
         aggregate gross sales of Joint Development Products in North America
         made by the Parties under this Agreement; PROVIDED, HOWEVER, that a
         Party shall not have the right to distribute a Joint Development
         Product in North America unless it has the capability and capacity to
         do so, as determined by the applicable North America Commercialization
         Project Team; and further provided that [**] shall require the Parties
         to [**].

6.9      COMMERCIALIZATION EXPENSE AND BUDGET.

         6.9.1    Expenses related to Commercialization of Joint Development
                  Products sold in North America shall be provided for in a
                  budget to be included in the Global Commercialization Plan and
                  the North America Commercialization Plan, and shall be shared
                  on a Joint Development Product-by-Joint Development Product
                  basis pursuant to Section 8.2 as follows: (a) Millennium and
                  Aventis shall each bear fifty percent (50%)


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                  of NA Commercialization Expense and NA License Fees for the
                  Joint Development Product, and (b) Millennium and Aventis
                  shall each bear a portion of all NA/Ex-NA Commercialization
                  Expenses and NA/Ex-NA License Fees for the Joint Development
                  Product equal to fifty percent (50%) of the NA Percentage. For
                  clarity, Aventis shall also bear a percentage of the NA/Ex-NA
                  Commercialization Expenses and NA/Ex-NA License Fees for the
                  Joint Development Product equal to one hundred percent (100%)
                  less the NA Percentage and shall bear one hundred percent
                  (100%) of the Commercialization expense relating solely to ROW
                  Commercialization that is not relevant to NA/Ex-NA
                  Commercialization.

         6.9.2    The budget set forth in each Global Commercialization Plan
                  shall detail the NA/Ex-NA Marketing Expense, NA/Ex-NA Medical
                  Expense and NA/Ex-NA License Fees budgeted to be incurred by
                  each Party during each calendar year. The budget set forth in
                  each North America Commercialization Plan shall detail the NA
                  Marketing Expense, NA Medical Expense, Field Force Expense and
                  NA License Fees budgeted to be incurred by each Party during
                  each calendar year.

         6.9.3    Each Joint Commercialization Project Team shall review on a
                  quarterly basis the NA/Ex-NA Commercialization Expense and
                  NA/Ex-NA License Fees against the budget for such expenses in
                  the applicable calendar year. If in the course of its
                  quarterly review of NA/Ex-NA Commercialization Expense and
                  NA/Ex-NA License Fees, any Joint Commercialization Project
                  Team should determine for any Joint Development Product that
                  the actual amounts incurred for NA/Ex-NA Marketing Expense,
                  NA/Ex-NA Medical Expense or NA/Ex-NA License Fees are likely
                  to be higher than budgeted, the Joint Commercialization
                  Project Team shall review the reasons for such potential
                  overrun and determine whether such overrun is appropriate. If
                  the Joint Commercialization Project Team determines that such
                  overrun is appropriate, the Joint Commercialization Project
                  Team will assess whether such overrun is likely to result in
                  an overrun of the overall NA/Ex-NA Commercialization Budget
                  and if required, will agree on a revised NA/Ex-NA
                  Commercialization Budget so that no overrun is expected. If
                  the Joint Commercialization Project Team determines that such
                  overrun is not appropriate, the Joint Commercialization
                  Project Team will take such actions as required to remedy the
                  situation.

         6.9.4    Each North America Commercialization Project Team shall review
                  on a quarterly basis the NA Commercialization Expense and NA
                  License Fees against the budget for such expenses in the
                  applicable calendar year. If in the course of its quarterly
                  review of NA Commercialization Expense and NA License Fees,
                  any North America Commercialization Project Team should
                  determine for any Joint Development Product that the actual
                  amounts incurred for NA Marketing Expense, NA Medical Expense,
                  Field Force Expense or NA License Fees are likely to be higher
                  than budgeted, the North America Commercialization Project
                  Team shall review the


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                  reasons for such potential overrun and determine whether such
                  overrun is appropriate. If the North America Commercialization
                  Project Team determines that such overrun is appropriate, the
                  North America Commercialization Project Team will assess
                  whether such overrun is likely to result in an overrun of the
                  overall NA Commercialization Budget and if required, will
                  agree on a revised NA Commercialization Budget so that no
                  overrun is expected. If the North America Commercialization
                  Project Team determines that such overrun is not appropriate,
                  the North America Commercialization Project Team will take
                  such actions as required to remedy the situation.

6.10     PUBLIC STATEMENTS REGARDING JOINT DEVELOPMENT PRODUCTS. Each Party
         shall ensure that no claims or representations in respect of the Joint
         Development Products or the characteristics thereof are made by or on
         behalf of it (by members of its sales force or otherwise) which do not
         represent an accurate summary or explanation of the labeling of the
         Joint Development Product or a portion thereof, except to the extent
         permitted by Law.

6.11     COMPLIANCE WITH LAWS. Each Party agrees to comply with all applicable
         Laws with respect to the Commercialization of Joint Development
         Products in North America. Neither Party shall be required to undertake
         any activity relating to the Commercialization of Joint Development
         Products in North America that it believes, in good faith, may violate
         any Law.

6.12     UNILATERAL COMMERCIALIZATION. The Developing Party with respect to a
         Unilateral Development Compound shall have the right to Commercialize
         related UDC Products on a worldwide basis; provided that the Developing
         Party shall provide the other Party with a quarterly report concerning
         the status of its Commercialization of any such UDC Products.
         Notwithstanding the foregoing, if the Developing Party intends to
         Commercialize a UDC Product in collaboration with a Third Party (or
         grant a license to a Third Party to do any of the foregoing), the
         Developing Party shall provide the other Party with an opportunity to
         negotiate terms under which the other Party would collaborate in or be
         granted a license with respect to such Commercialization (a "Product
         Right of First Negotiation"), provided that a Product Right of First
         Negotiation shall not apply to the retention of a contract sales force
         or to a product distribution or contract manufacturing arrangement or
         other outsourced marketing, advertising or promotion activities (unless
         such arrangement is with a Significant Pharmaceutical Enterprise). A
         Product Right of First Negotiation shall operate as follows:


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         6.12.1   The Developing Party shall promptly notify the other Party in
                  writing (the "Product Notification") of its intention to seek
                  a collaborator or licensee for the Commercialization of the
                  relevant UDC Product and shall provide to the other Party a
                  reasonably detailed written description of the UDC Product and
                  such proposed UDC collaboration or license, together with all
                  relevant data and information relating to the Joint
                  Development Product which has not previously been provided to
                  the other Party.

         6.12.2   Within [**] of its receipt of the Product Notification (the
                  "Product Response Period"), the other Party shall notify the
                  Developing Party of its interest, if any, in initiating
                  discussions regarding such proposed UDC collaboration or
                  license.

         6.12.3   In the event that the other Party notifies the Developing
                  Party prior to the termination of the Product Response Period
                  that it has an interest in participating in such proposed UDC
                  collaboration or in receiving such license (a "Product
                  Expression of Interest"), then the Parties shall negotiate in
                  good faith in an effort to reach a definitive agreement
                  regarding such UDC collaboration or license for a period of up
                  to [**] from the date of the Developing Party's receipt of the
                  Product Expression of Interest.

         6.12.4   In the event that the Parties reach a definitive agreement
                  with respect to such UDC Product pursuant to Section 6.12.3,
                  such UDC Product shall no longer be designated a Unilateral
                  Development Product and the rights and obligations of the
                  Parties with respect to such product shall be governed by the
                  terms of such definitive agreement and not this Agreement.

         6.12.5   In the event that (a) the other Party fails to notify the
                  Developing Party prior to the termination of the Product
                  Response Period that it is interested in collaborating with or
                  obtaining a license from the Developing Party with respect to
                  such Unilateral Development Product, or (b) the other Party
                  notifies the Developing Party prior to the termination of the
                  Product Response Period that it has no interest in such
                  collaboration or license, or (c) the other Party timely
                  provides the Developing Party with a Product Expression of
                  Interest but the Parties fail to reach a definitive agreement
                  within the [**] period specified in Section 6.12.3, then the
                  Developing Party shall be free to enter into a collaboration
                  or license with a Third Party with respect to such UDC
                  Product; PROVIDED, HOWEVER, that the Developing Party may [**]
                  with a Third Party [**] to the Third Party, [**] to the
                  non-Developing Party.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         6.12.6   For the duration of the Product Response Period, and if the
                  other Party timely delivers the Product Expression of
                  Interest, the [**] term specified in Section 6.12.3, the
                  Developing Party may discuss the general outline of such
                  collaboration or license; PROVIDED HOWEVER, that the
                  Developing Party shall not negotiate such collaboration or
                  license with a Third Party, enter into any agreements with
                  such Third Party or propose terms to such Third Party on which
                  Millennium would be willing to consummate such collaboration
                  or license.

6.13     USE OF SUBCONTRACTORS. To the extent either Party wishes to perform
         some of its obligations regarding the North America Commercialization
         or NA/Ex-NA Commercialization through one or more subcontractors, it
         must obtain the written approval of the other Party prior to engaging
         such subcontractor, which approval shall not be unreasonably withheld
         or delayed. It is understood that as a condition to granting such
         approval, (a) the other Party shall be entitled to audit the proposed
         subcontractor using the same standards which it applies to the use of
         subcontractors in the Commercialization of its other products, and (b)
         the subcontractor must undertake in writing obligations of
         confidentiality and non-use regarding the other Party's Confidential
         Information which are substantially the same as those undertaken by
         Aventis or Millennium pursuant to Article 9 hereof. In the event a
         Party performs one or more of its obligations regarding North America
         Commercialization or NA/Ex-NA Commercialization through the use of a
         subcontractor, then such Party shall at all times be responsible for
         the performance of such subcontractor. For the avoidance of doubt, it
         is understood that an Affiliate of a Party shall not be deemed to be a
         subcontractor of such Party. For clarity, the provisions of this
         Section 6.13 are not intended to apply to contracts with individual
         consultants, small market research studies and other contracts of
         similarly small financial magnitude.

                                   ARTICLE 7

                                    LICENSES

7.1      MILLENNIUM GRANTS

         7.1.1    RESEARCH LICENSES.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (a)      ACTIVITIES UNDER RESEARCH PROGRAM. Subject to the
                           terms and conditions of this Agreement (including the
                           license grants set forth in this Article 7 [**]) and
                           any applicable [**], Millennium hereby grants to
                           Aventis a worldwide, co-exclusive,
                           non-royalty-bearing license during the Research
                           Program Term, under Millennium's rights to the
                           Millennium Ex-Program Intellectual Property and the
                           Program Intellectual Property, to (A) identify and
                           validate targets for the identification, evaluation
                           and optimization of Small Molecules for use [**], (B)
                           identify Small Molecules through the use of such
                           targets, and (C) undertake Pre-EDC Research
                           Evaluation of such Small Molecules, in each case, in
                           the conduct of the Research Program. Such license
                           shall further include the right to grant sublicenses
                           to Affiliates of Aventis and to Third Parties that
                           are approved by the Joint Research Committee.

                  (b)      AVENTIS SINGLE-PARTY RESEARCH TARGETS. Subject to the
                           terms and conditions of this Agreement and any
                           applicable Burdened Technology Obligations,
                           Millennium hereby grants to Aventis a worldwide,
                           non-exclusive, non-royalty-bearing license, under
                           Millennium's rights to the Millennium Ex-Program
                           Intellectual Property and the Program Intellectual
                           Property (excluding Program Compounds other than the
                           related SPRT Compounds), to (A) validate Aventis
                           Single-Party Research Targets for the identification,
                           evaluation and optimization of Small Molecules for
                           use [**], (B) identify Small Molecules through the
                           use of such Aventis Single-Party Research Targets and
                           (C) undertake Pre-EDC Research Evaluation of such
                           Small Molecules; PROVIDED, HOWEVER, THAT, with
                           respect to each Aventis Single-Party Research Target,
                           such license shall be limited to know-how disclosed
                           to Aventis prior to, and to Patent Rights which exist
                           as of or which claim priority from Patent Rights
                           which exist as of, the date such target is designated
                           an Aventis Single-Party Research Target. Such license
                           shall further include the right to grant sublicenses
                           to Affiliates of Aventis and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           Millennium hereby grants to Aventis a worldwide,
                           non-exclusive, non-royalty-bearing license, under
                           Millennium's rights to the Program Intellectual
                           Property, to use Scientifically-Qualified Targets to
                           identify, evaluate and optimize Essential
                           Pharmacogenomic Products or Services. Such license
                           shall further include the right to grant sublicenses
                           to Affiliates of Aventis and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable [**],
                           and on a Scientifically-Qualified
                           Target-by-Scientifically-Qualified Target basis,
                           Millennium hereby grants to Aventis a worldwide,
                           non-exclusive, non-royalty-bearing license, under
                           Millennium's Patent Rights (excluding the Millennium
                           Research Program Chemistry Intellectual Property), to
                           use Scientifically-Qualified Targets to identify,
                           evaluate and optimize Small Molecules for use [**];
                           PROVIDED, HOWEVER, that with respect to each
                           Scientifically-Qualified Target, such license shall
                           be limited to (i) know-how disclosed to Aventis prior
                           to the date such target is designated a
                           Scientifically-Qualified Target, (ii) Patent Rights
                           which exist as of the date such target is designated
                           a Scientifically-Qualified Target, and (iii) any
                           claim of a patent which (A) claims priority from a
                           patent application within Patent Rights which exists
                           as of the date such target is designated an
                           Scientifically-Qualified Target and (B) is adequately
                           supported in such application from which it claims
                           priority to satisfy the requirements of 35 U.S.C.
                           112. Such license shall further include the right to
                           grant sublicenses to Affiliates of Aventis and to
                           Third Parties in accordance with the terms set forth
                           in Section 7.2.5.

                  (e)      RESEARCH LICENSE TO PROGRAM COMPOUNDS.

                           (i)      Subject to the terms and conditions of this
                                    Agreement and any applicable Burdened
                                    Technology Obligations, Millennium hereby
                                    grants to Aventis a worldwide,
                                    non-exclusive, non-royalty-bearing license,
                                    under Millennium's Program Patent Rights to
                                    use a Program Compound for internal research
                                    purposes only; provided, however, such
                                    license shall not include the right to use
                                    the corresponding Program Compound Family
                                    outside the Research Program to identify,
                                    evaluate and optimize Small Molecules as
                                    Ex-


                                      Page 74
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                                    Program Products directed to the same
                                    Scientifically-Qualified Target as to which
                                    such Program Compound Family was generated.
                                    Such license shall remain in effect in
                                    perpetuity except during the periods
                                    described in Sections 7.1.1(e)(ii) and
                                    (iii).

                           (ii)     Upon selection of a Lead Compound, with
                                    respect to a Program Compound within the
                                    corresponding Lead Compound Family, the
                                    license of Section 7.1.1(e)(i) shall be
                                    suspended with respect to such Program
                                    Compound during the period from selection of
                                    such Lead Compound until the earlier of (A)
                                    discontinuation of all activities in the
                                    Research Program relating to such Lead
                                    Compound Family or (B) the decision of the
                                    Joint Research Committee not to select such
                                    Program Compound as an EDC Compound or a
                                    Back-Up Compound.

                           (iii)    If a Lead Compound directed to a target has
                                    been selected by the Joint Research
                                    Committee prior to such target being
                                    designated as a Millennium Single-Party
                                    Research Target, with respect to the
                                    corresponding Lead Compound Family, the
                                    license of Section 7.1.1(e)(i) shall be
                                    suspended with respect to such Lead Compound
                                    Family during the period from designation of
                                    such Millennium Single-Party Research Target
                                    until the discontinuation of all activities
                                    by Millennium relating to such Lead Compound
                                    Family with respect to such Millennium
                                    Single-Party Research Target.

         7.1.2    DEVELOPMENT LICENSES.

                  (a)      JOINT DEVELOPMENT PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on an EDC
                           Compound-by-EDC Compound basis, Millennium hereby
                           grants to Aventis a worldwide, non-royalty-bearing
                           license, under Millennium's rights to the Millennium
                           Ex-Program Intellectual Property and the Program
                           Intellectual Property, to Develop Joint Development
                           Compounds for JD Products. Such license shall be
                           exclusive outside of North America and shall be
                           co-exclusive (with Millennium) within North America,
                           and shall further include the right to grant
                           sublicenses to Affiliates of Aventis and to Third
                           Parties that are approved by the relevant Joint
                           Development Committee.


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                  (b)      AVENTIS SINGLE-PARTY TARGET PRODUCTS AND AVENTIS UDC
                           PRODUCTS. Subject to the terms and conditions of this
                           Agreement (including the license grants set forth in
                           this Article 7 with respect to Ex-Program Products)
                           and any applicable Burdened Technology Obligations,
                           and on a compound-by-compound basis, Millennium
                           hereby grants to Aventis a worldwide, exclusive,
                           non-royalty-bearing license, under Millennium's
                           rights to the Millennium Ex-Program Intellectual
                           Property and the Program Intellectual Property
                           (excluding Program Compounds other than the related
                           SPRT Compounds that are specified in Section
                           2.7.3(b)(ii) or that are Active against the relevant
                           Single-Party Research Target), to (i) Develop Small
                           Molecules identified through the use of Aventis
                           Single-Party Research Targets for Aventis
                           Single-Party Target Products and (ii) Develop Aventis
                           Unilateral Development Compounds for Aventis UDC
                           Products; PROVIDED, HOWEVER, that, with respect to
                           each Aventis Single-Party Research Target or Aventis
                           Unilateral Development Compound, as the case may be,
                           such license shall be limited to know-how disclosed
                           to Aventis prior to, and to Patent Rights which exist
                           as of or which claim priority from Patent Rights
                           which exist as of, the date such target is designated
                           an Aventis Single-Party Research Target or such
                           compound is designated an Aventis Unilateral
                           Development Compound, as the case may be. Such
                           license shall further include the right to grant
                           sublicenses to Affiliates of Aventis and to Third
                           Parties in accordance with the terms set forth in
                           Section 7.2.5.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           and on a compound-by-compound basis, Millennium
                           hereby grants to Aventis a worldwide, non-exclusive,
                           non-royalty-bearing license, under Millennium's
                           rights to the Program Intellectual Property, to use
                           Scientifically-Qualified Targets to Develop Essential
                           Pharmacogenomic Products or Services. Such license
                           shall further include the right to grant sublicenses
                           to Affiliates of Aventis and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on a
                           compound-by-compound basis, Millennium hereby grants
                           to Aventis a worldwide, non-exclusive,
                           non-royalty-bearing license, under Millennium's
                           rights to the Program Intellectual Property
                           (excluding the Millennium Research Program Chemistry
                           Intellectual Property), to use
                           Scientifically-Qualified Targets to Develop
                           Ex-Program Products [**]; PROVIDED, HOWEVER, that,
                           with respect to each Scientifically-Qualified Target,
                           such license shall be limited to (i) know-how
                           disclosed to Aventis prior to the date such target is
                           designated a Scientifically-Qualified Target, (ii)
                           Patent Rights which exist as of the date such target
                           is designated a Scientifically-Qualified Target, and
                           (iii) any claim of a patent which (A) claims priority
                           from a patent application within Patent Rights which
                           exists as of the date such target is designated a
                           Scientifically-Qualified Target and (B) is adequately
                           supported in such application from, which it claims
                           priority to satisfy the requirements of 35 U.S.C.
                           112. Such license shall further include the right to
                           grant sublicenses to Affiliates of Aventis and to
                           Third Parties in accordance with the terms set forth
                           in Section 7.2.5.

         7.1.3    COMMERCIALIZATION LICENSES.

                  (a)      JD PRODUCTS. Subject to the terms and conditions of
                           this Agreement and any applicable Burdened Technology
                           Obligations, and on a JD Product-by-JD Product basis,
                           Millennium hereby grants to Aventis a worldwide
                           license, under Millennium's rights to the Millennium
                           Ex-Program Chemistry Intellectual Property and the
                           Program Intellectual Property, to Commercialize JD
                           Products in the Territory. Such license shall be
                           exclusive outside of North America and shall be
                           co-exclusive (with Millennium) within North America,
                           and shall carry an obligation of profit-sharing with
                           respect to JD Products sold in North America and
                           shall be royalty-bearing with respect to JD Products
                           sold outside of North America. Such license shall
                           further include the right to grant sublicenses to
                           Affiliates of Aventis and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5
                           (provided that within North America, any sublicense
                           to a Third Party must be approved by the relevant
                           Joint Commercialization Committee).


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (b)      AVENTIS SINGLE-PARTY TARGET PRODUCTS AND AVENTIS UDC
                           PRODUCTS. Subject to the terms and conditions of this
                           Agreement and any applicable Burdened Technology
                           Obligations, and on a product-by-product basis,
                           Millennium hereby grants to Aventis a worldwide,
                           exclusive, royalty-bearing license, under
                           Millennium's rights to the Millennium Ex-Program
                           Intellectual Property and the Program Intellectual
                           Property (excluding Program Compounds other than the
                           related SPRT Compounds that are specified in Section
                           2.7.3(b)(ii) or that are Active against the relevant
                           Single-Party Research Target), to Commercialize
                           Aventis Single-Party Target Products and Aventis UDC
                           Products in the Territory; PROVIDED, HOWEVER, that,
                           with respect to each Aventis Single-Party Target
                           Product or Aventis Unilateral Development Compound,
                           as the case may be, such license shall be limited to
                           know-how disclosed to Aventis prior to, and to Patent
                           Rights which exist as of or which claim priority from
                           Patent Rights which exist as of, the date the target
                           used to identify, evaluate, optimize and/or Develop
                           such Aventis Single-Party Target Product is
                           designated an Aventis Single-Party Research Target or
                           such compound is designated an Aventis Unilateral
                           Development Compound, as the case may be. Such
                           license shall further include the right to grant
                           sublicenses to Affiliates of Aventis and to Third
                           Parties in accordance with the terms set forth in
                           Section 7.2.5.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           and on a product-by-product or service-by-service
                           basis, Millennium hereby grants to Aventis a
                           worldwide, non-exclusive, non-royalty-bearing
                           license, under Millennium's rights to the Program
                           Intellectual Property, to Commercialize Essential
                           Pharmacogenomic Products or Services in the
                           Territory. Such license shall further include the
                           right to grant sublicenses to Affiliates of Aventis
                           and to Third Parties in accordance with the terms set
                           forth in Section 7.2.5.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on an Ex-Program
                           Product-by-Ex-Program Product basis, Millennium
                           hereby grants to Aventis a worldwide, non-exclusive,
                           royalty-bearing license, under Millennium's rights to
                           the Program Intellectual Property (excluding the
                           Millennium Research Program Chemistry Intellectual
                           Property), to Commercialize Ex-Program Products [**]
                           in the Territory; PROVIDED, HOWEVER, that, with
                           respect to each Ex-Program Product, such license
                           shall be limited


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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                           to (i) know-how disclosed to Aventis prior to the
                           date the target used to identify, evaluate, optimize
                           and/or Develop such Ex-Program Product is designated
                           a Scientifically-Qualified Target, (ii) Patent Rights
                           which exist as of the date the target used to
                           identify, evaluate, optimize and/or Develop such
                           Ex-Program Product is designated a
                           Scientifically-Qualified Target, and (iii) any claim
                           of a patent which (A) claims priority from a patent
                           application within Patent Rights which exists as of
                           the date the target used to identify, evaluate,
                           optimize and/or Develop such Ex-Program Product is
                           designated a Scientifically-Qualified Target, and (B)
                           in adequately supported in such application from
                           which it claims priority to satisfy the requirements
                           of 35 U.S.C. 112. Such license shall further include
                           the right to grant sublicenses to Affiliates of
                           Aventis and to Third Parties in accordance with the
                           terms set forth in Section 7.2.5.

         7.1.4    LICENSE GRANTS ON THE EXERCISE OF AN OPTION.

                  (a)      GT PRODUCTS. Subject to the terms and conditions of
                           this Agreement and any applicable Burdened Technology
                           Obligations, upon the exercise of a GT Option,
                           Millennium hereby grants to Aventis (A) a worldwide,
                           exclusive, non-royalty bearing license, under
                           Millennium's rights to Program Intellectual Property,
                           to validate and use the Potential GT Target that is
                           the subject of such option for the discovery and
                           evaluation of GT Products [**] and (B) a worldwide,
                           exclusive, royalty-bearing license, under
                           Millennium's rights to the Program Intellectual
                           Property, to Develop and Commercialize such GT
                           Products. Such license shall further include the
                           rights to grant sublicenses to Affiliates of Aventis
                           and to Third Parties in accordance with the terms set
                           forth in Section 7.2.5.

                  (b)      VACCINE PRODUCTS. Subject to the terms and conditions
                           of this Agreement and any applicable Burdened
                           Technology Obligations, upon the exercise of a
                           Vaccine Option, Millennium hereby grants to Aventis
                           (A) a worldwide, exclusive, non-royalty bearing
                           license, under Millennium's rights to Program
                           Intellectual Property, to validate and use the
                           Potential Vaccine Target that is the subject of such
                           option for the discovery and evaluation of Vaccine
                           Products [**] and (B) a worldwide, exclusive,
                           royalty-bearing license, under Millennium's rights to
                           the Program Intellectual Property, to Develop and
                           Commercialize such Vaccine Products. Such license
                           shall further include the rights to grant sublicenses
                           to Affiliates of Aventis and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.


                                      Page 79
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

7.2      AVENTIS GRANTS.

         7.2.1    RESEARCH LICENSES.

                  (a)      ACTIVITIES UNDER RESEARCH PROGRAM. Subject to the
                           terms and conditions of this Agreement (including the
                           license grants set forth in this Article 7 with
                           respect to Ex-Program Products) and any applicable
                           Burdened Technology Obligations, Aventis hereby
                           grants to Millennium a worldwide, co-exclusive,
                           non-royalty-bearing license during the Research
                           Program Term, under Aventis' rights to the Aventis
                           Ex-Program Intellectual Property and the Program
                           Intellectual Property, to (A) identify and validate
                           targets for the identification, evaluation, and
                           optimization of Small Molecules [**], (B) identify
                           Small Molecules through the use of such targets and
                           (C) undertake Pre-EDC Research Evaluation of such
                           Small Molecules, in each case, in the conduct of the
                           Research Program. Such license shall further include
                           the right to grant sublicenses to Affiliates of
                           Millennium and to Third Parties that are approved by
                           the Joint Research Committee.

                  (b)      MILLENNIUM SINGLE-PARTY RESEARCH TARGETS. Subject to
                           the terms and conditions of this Agreement and any
                           applicable Burdened Technology Obligations, Aventis
                           hereby grants to Millennium a worldwide,
                           non-exclusive, non-royalty-bearing license, under
                           Aventis' rights to the Aventis Ex-Program
                           Intellectual Property and the Program Intellectual
                           Property (excluding Program Compounds other than the
                           related SPRT Compounds), to (A) validate Millennium
                           Single-Party Research Targets for the identification,
                           evaluation and optimization of Small Molecules [**],
                           (B) identify Small Molecules through the use of such
                           Millennium Single-Party Research Targets and (C)
                           undertake Pre-EDC Research Evaluation of such Small
                           Molecules; PROVIDED, HOWEVER, THAT, with respect to
                           each Millennium Single-Party Research Target, such
                           license shall be limited to know-how disclosed to
                           Millennium prior to, and to Patent Rights which exist
                           as of or which claim priority from Patent Rights
                           which exist as of, the date such target is designated
                           a Millennium Single-Party Research Target. Such
                           license shall further include the right to grant
                           sublicenses to Affiliates of Millennium and to Third
                           Parties in accordance with the terms set forth in
                           Section 7.2.5.


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           Aventis hereby grants to Millennium a worldwide,
                           non-exclusive, non-royalty-bearing license, under
                           Aventis' rights to the Program Intellectual Property,
                           to use Scientifically-Qualified Targets to identify,
                           evaluate and optimize Essential Pharmacogenomic
                           Products or Services. Such license shall further
                           include the right to grant sublicenses to Affiliates
                           of Millennium and to Third Parties in accordance with
                           the terms set forth in Section 7.2.5.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on a
                           Scientifically-Qualified
                           Target-by-Scientifically-Qualified Target basis,
                           Aventis hereby grants to Millennium a worldwide,
                           non-exclusive, non-royalty-bearing license under
                           Aventis' rights to the Program Intellectual Property
                           (excluding the Aventis Research Program Chemistry
                           Intellectual Property), to use
                           Scientifically-Qualified Targets to identify,
                           evaluate and optimize Small Molecules [**]; PROVIDED,
                           HOWEVER, that with respect to each Scientifically-
                           Qualified Target, such license shall be limited to
                           (i) know-how disclosed to Millennium prior to the
                           date such target is designated a Scientifically-
                           Qualified Target, (ii) Patent Rights which exist as
                           of the date such target is designated a
                           Scientifically-Qualified Target, and (iii) any
                           claim of a patent which (A) claims priority from a
                           patent application within Patent Rights which exists
                           as of the date such target is designated a
                           Scientifically-Qualified Target and (B) is adequately
                           supported in such application from, which it claims
                           priority to satisfy the requirements of 35 U.S.C.
                           112. Such license shall further include the right to
                           grant sublicenses to Affiliates of Millennium and to
                           Third Parties in accordance with the terms set forth
                           in Section 7.2.5.

                  (e)      RESEARCH LICENSE TO PROGRAM COMPOUNDS.

                           (i)      Subject to the terms and conditions of this
                                    Agreement and any applicable Burdened
                                    Technology Obligations, Aventis hereby
                                    grants to Millennium a worldwide,
                                    non-exclusive, non-royalty-bearing license,
                                    under Aventis' Program Patent Rights to use
                                    a Program Compound for internal research
                                    purposes only; provided, however, such
                                    license shall not include the right to use
                                    the corresponding Program Compound Family
                                    outside the Research Program to identify,
                                    evaluate and optimize Small Molecules as
                                    Ex-


                                      Page 81
<PAGE>


                                    Program Products directed to the same
                                    Scientifically-Qualified Target as to which
                                    such Program Compound Family was generated.
                                    Such license shall remain in effect in
                                    perpetuity except during the periods
                                    described in Sections 7.1.1(e)(ii) and
                                    (iii).

                           (ii)     Upon selection of a Lead Compound, with
                                    respect to a Program Compound within the
                                    corresponding Lead Compound Family, the
                                    license of Section 7.2.1(e)(i) shall be
                                    suspended with respect to such Program
                                    Compound during the period from selection of
                                    such Lead Compound until the earlier of (A)
                                    discontinuation of all activities in the
                                    Research Program relating to such Lead
                                    Compound Family or (B) the decision of the
                                    Joint Research Committee not to select such
                                    Program Compound as an EDC Compound or a
                                    Back-Up Compound.

                           (iii)    If a Lead Compound directed to a target has
                                    been selected by the Joint Research
                                    Committee prior to such target being
                                    designated as an Aventis Single-Party
                                    Research Target, with respect to the
                                    corresponding Lead Compound Family, the
                                    license of Section 7.2.1(e)(i) shall be
                                    suspended with respect to such Lead Compound
                                    Family during the period from designation of
                                    such Aventis Single-Party Research Target
                                    until the discontinuation of all activities
                                    by Aventis relating to such Lead Compound
                                    Family with respect to such Aventis
                                    Single-Party Research Target.

         7.2.2    DEVELOPMENT LICENSES.

                  (a)      JOINT DEVELOPMENT PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on an EDC
                           Compound-by-EDC Compound basis, Aventis hereby grants
                           to Millennium a worldwide, co-exclusive (with
                           Aventis), non-royalty-bearing license, under Aventis'
                           rights to the Aventis Ex-Program Intellectual
                           Property and the Program Intellectual Property, to
                           Develop Joint Development Compounds for JD Products.
                           Such license shall be limited to Development relevant
                           for North America and shall further include the right
                           to grant sublicenses to Affiliates of Millennium and
                           to Third Parties that are approved in by the relevant
                           Joint Development Committee.


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<PAGE>


                  (b)      MILLENNIUM SINGLE-PARTY TARGET PRODUCTS AND
                           MILLENNIUM UDC PRODUCTS. Subject to the terms and
                           conditions of this Agreement (including the license
                           grants set forth in this Article 7 with respect to
                           Ex-Program Products) and any applicable Burdened
                           Technology Obligations, and on a compound-by-compound
                           basis, Aventis hereby grants to Millennium a
                           worldwide, exclusive, non-royalty-bearing license,
                           under Aventis' rights to the Aventis Ex-Program
                           Intellectual Property and the Program Intellectual
                           Property (excluding Program Compounds other than the
                           related SPRT Compounds that are specified in Section
                           2.7.3(b)(ii) or that are Active against the relevant
                           Single-Party Research Target), to (i) Develop Small
                           Molecules identified through the use of Millennium
                           Single-Party Research Targets for Millennium
                           Single-Party Target Products, and (ii) Develop
                           Millennium Unilateral Development Compounds for
                           Millennium UDC Products; PROVIDED, HOWEVER, that,
                           with respect to each Millennium Single-Party Research
                           Target or Millennium Unilateral Development Compound,
                           as the case may be, such license shall be limited to
                           know-how disclosed to Millennium prior to, and to
                           Patent Rights which exist as of or which claim
                           priority from Patent Rights which exist as of, the
                           date such target is designated a Millennium
                           Single-Party Research Target or such compound is
                           designated a Millennium Unilateral Development
                           Compound, as the case may be. Such license shall
                           further include the right to grant sublicenses to
                           Affiliates of Millennium and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           and on a compound-by-compound basis, Aventis hereby
                           grants to Millennium a worldwide, non-exclusive,
                           non-royalty-bearing license, under Aventis' rights to
                           the Program Intellectual Property, to use
                           Scientifically-Qualified Targets to Develop Essential
                           Pharmacogenomic Products or Services. Such license
                           shall further include the right to grant sublicenses
                           to Affiliates of Millennium and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.


                                      Page 83
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on a
                           compound-by-compound basis, Aventis hereby grants to
                           Millennium a worldwide, non-exclusive,
                           non-royalty-bearing license, under Aventis' rights to
                           the Program Intellectual Property (excluding the
                           Aventis Research Program Chemistry Intellectual
                           Property), to use Scientifically-Qualified Targets to
                           Develop Ex-Program Products [**]; PROVIDED, HOWEVER,
                           that with respect to each Scientifically-Qualified
                           Target, such license shall be limited to (i) know-how
                           disclosed to Millennium prior to the date such target
                           is designated a Scientifically-Qualified Target, (ii)
                           Patent Rights which exist as of the date such target
                           is designated a Scientifically-Qualified Target, and
                           (iii) any claim of a patent which (A) claims priority
                           from a patent application within Patent Rights which
                           exists as of the date such target is designated a
                           Scientifically-Qualified Target and (B) is adequately
                           supported in such application from which it claims
                           priority to satisfy the requirements of 35 U.S.C.
                           112. Such license shall further include the right to
                           grant sublicenses to Affiliates of Millennium and to
                           Third Parties in accordance with the terms set forth
                           in Section 7.2.5.

         7.2.3    COMMERCIALIZATION LICENSES.

                  (a)      JD PRODUCTS. Subject to the terms and conditions of
                           this Agreement and any applicable Burdened Technology
                           Obligations, and on a JD Product-by-JD Product basis,
                           Aventis hereby grants to Millennium a, co-exclusive
                           (with Aventis) license, under Aventis' rights to the
                           Aventis Ex-Program Intellectual Property and the
                           Program Intellectual Property, to Commercialize JD
                           Products in North America. Such license shall carry
                           an obligation of profit-sharing with respect to JD
                           Products sold in North America. Such license shall
                           further include the right to grant sublicenses to
                           Affiliates of Millennium, and to Third Parties that
                           are approved by the relevant Joint Commercialization
                           Committee.


                                      Page 84
<PAGE>


                  (b)      MILLENNIUM SINGLE-PARTY TARGET PRODUCTS AND
                           MILLENNIUM UDC PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on a
                           product-by-product basis, Aventis hereby grants to
                           Millennium a worldwide, exclusive, royalty-bearing
                           license, under Aventis' rights to the Aventis
                           Ex-Program Intellectual Property and the Program
                           Intellectual Property (excluding Program Compounds
                           other than the related SPRT Compounds that are
                           specified in Section 2.7.3(b)(ii) or that are Active
                           against the relevant Single-Party Research Target),
                           to Commercialize Millennium Single-Party Target
                           Products and Millennium UDC Products in the
                           Territory; PROVIDED, HOWEVER, that, with respect to
                           each Millennium Single-Party Target Product or
                           Millennium Unilateral Development Compound, as the
                           case may be, such license shall be limited to
                           know-how disclosed to Millennium prior to, and to
                           Patent Rights which exist as of or which claim
                           priority from Patent Rights which exist as of, the
                           date the target used to identify, evaluate, optimize
                           and/or Develop such Millennium Single-Party Target
                           Product is designated a Millennium Single-Party
                           Research Target or such compound is designated a
                           Millennium Unilateral Development Compound, as the
                           case may be. Such license shall further include the
                           right to grant sublicenses to Affiliates of
                           Millennium and to Third Parties in accordance with
                           the terms set forth in Section 7.2.5. Aventis shall
                           also assign to Millennium all of its rights, title
                           and interest in any trademark or service mark adopted
                           by Aventis in connection with the Millennium UDC
                           Product.

                  (c)      ESSENTIAL PHARMACOGENOMIC PRODUCTS OR SERVICES.
                           Subject to the terms and conditions of this Agreement
                           and any applicable Burdened Technology Obligations,
                           and on a product-by-product or service-by-service
                           basis, Aventis hereby grants to Millennium a
                           worldwide, non-exclusive, non-royalty-bearing
                           license, under Aventis' rights to the Program
                           Intellectual Property, to Commercialize Essential
                           Pharmacogenomic Products or Services in the
                           Territory. Such license shall further include the
                           right to grant sublicenses to Affiliates of
                           Millennium and to Third Parties in accordance with
                           the terms set forth in Section 7.2.5.


                                      Page 85
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (d)      EX-PROGRAM PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, and on an Ex-Program
                           Product-by-Ex-Program Product basis, Aventis hereby
                           grants to Millennium a worldwide, non-exclusive,
                           royalty-bearing license, under Aventis' rights to the
                           Program Intellectual Property (excluding the Aventis
                           Research Program Chemistry Intellectual Property), to
                           Commercialize Ex-Program Products [**] in the
                           Territory; PROVIDED, HOWEVER, that with respect to
                           each Ex-Program Product, such license shall be
                           limited to (i) know-how disclosed to Millennium prior
                           to the date the target used to identify, evaluate,
                           optimize and/or Develop such Ex-Program Product is
                           designated a Scientifically-Qualified Target, (ii)
                           Patent Rights which exist as of the date the target
                           used to identify, evaluate, optimize and/or Develop
                           such Ex-Program Product is designated a
                           Scientifically-Qualified Target, and (iii) any claim
                           of a patent which (A) claims priority from a patent
                           application within Patent Rights which exists as of
                           the date the target used to identify, evaluate,
                           optimize and/or Develop such Ex-Program Product is
                           designated a Scientifically-Qualified Target, and (B)
                           is adequately supported in such application from
                           which it claims priority to satisfy the requirements
                           of 35 U.S.C. 112. Such license shall further include
                           the right to grant sublicenses to Affiliates of
                           Millennium and to Third Parties in accordance with
                           the terms set forth in Section 7.2.5.

         7.2.4    LICENSE GRANTS ON THE EXERCISE OF AN OPTION.

                  (a)      ANTIBODY PRODUCTS. Subject to the terms and
                           conditions of this Agreement and any applicable
                           Burdened Technology Obligations, upon the exercise of
                           an Antibody Option, Aventis hereby grants to
                           Millennium (A) a worldwide, exclusive, non-royalty
                           bearing license, under Aventis' rights to the Program
                           Intellectual Property, to validate and use the
                           Potential Antibody Target that is the subject of such
                           option for the discovery and evaluation of Antibody
                           Products [**] and (B) a worldwide, exclusive,
                           royalty-bearing license, under Aventis' rights to the
                           Program Intellectual Property, to Develop and
                           Commercialize such Antibody Products. Such license
                           shall further include the rights to grant sublicenses
                           to Affiliates of Millennium and to Third Parties in
                           accordance with the terms set forth in Section 7.2.5.


                                      Page 86

<PAGE>

                  (b)      DIAGNOSTIC PRODUCTS OR SERVICES. Subject to the terms
                           and conditions of this Agreement and any applicable
                           Burdened Technology Obligations, upon the exercise of
                           a Diagnostic Option, Aventis hereby grants to
                           Millennium (A) a worldwide, exclusive, non-royalty
                           bearing license, under Aventis' rights to the Program
                           Intellectual Property, to validate and use the
                           Potential Diagnostic Target that is the subject of
                           such option for the discovery and evaluation of
                           Diagnostic Products or Services to diagnose, in
                           humans, asthma, chronic obstructive pulmonary
                           disease, rheumatoid arthritis, multiple sclerosis
                           and/or inflammatory bowel disease and (B) a
                           worldwide, exclusive, royalty-bearing license, under
                           Aventis' rights to the Program Intellectual Property,
                           to Develop and Commercialize such Diagnostic Products
                           or Services. Such license shall further include the
                           rights to grant sublicenses to Affiliates of
                           Millennium and to Third Parties in accordance with
                           the terms set forth in Section 7.2.5.

         7.2.5    SUBLICENSE RIGHTS. Wherever in this Agreement either Party is
                  granted the right to grant sublicenses subject to this Section
                  7.2.5, such Party may exercise such right without obtaining
                  the prior approval of the other Party, provided that if such
                  sublicensee is a Third Party, the sublicensing Party shall
                  promptly notify the other Party of the identity of such Third
                  Party sublicensee; and PROVIDED, FURTHER, THAT such sublicense
                  occurs pursuant to a written agreement that subjects such
                  sublicensee to all relevant restrictions and limitations in
                  this Agreement. Each Party shall be jointly and severally
                  responsible with its sublicensees for failure by its
                  sublicensees to comply with, and each Party guarantees the
                  compliance by each of its sublicensees with, all such
                  applicable restrictions and limitations in accordance with the
                  terms and conditions of this Agreement.

7.3      RETAINED RIGHTS.

         7.3.1    AVENTIS RETAINED RIGHTS. With respect to this Agreement, any
                  rights of Aventis not expressly granted to Millennium under
                  the provisions of this Agreement shall be retained by Aventis,
                  including, without limitation, Aventis' rights to exploit
                  Program Intellectual Property Controlled by Aventis for (a)
                  any human health care applications based upon database and
                  information products or patient management tools and (b) any
                  applications outside of the human health care field.

         7.3.2    MILLENNIUM RETAINED RIGHTS. With respect to this Agreement,
                  any rights of Millennium not expressly granted to Aventis
                  under the provisions of this Agreement shall be retained by
                  Millennium, including, without limitation, Millennium's rights
                  to exploit Program Intellectual Property Controlled by
                  Millennium for (a) any human health care applications based
                  upon database and information products or patient management
                  tools and (b) any applications outside of the human health
                  care field.


                                      Page 87
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

7.4      SECTION 365(n) OF THE BANKRUPTCY CODE. All rights and licenses granted
         under or pursuant to any section of this Agreement are, and shall
         otherwise be deemed to be, for purposes of Section 365(n) of the
         Bankruptcy Code, licenses of rights to "intellectual property" as
         defined under Section 101(35A) of the Bankruptcy Code. The Parties
         shall retain and may fully exercise all of their respective rights and
         elections under the Bankruptcy Code. Upon the bankruptcy of any Party,
         the non-bankrupt Party shall further be entitled to a complete
         duplicate of (or complete access to, as appropriate) any such
         intellectual property, and such, if not already in its possession,
         shall be promptly delivered to the non-bankrupt Party, unless the
         bankrupt Party elects to continue, and continues, to perform all of its
         obligations under this Agreement.

7.5      CERTAIN COVENANTS REGARDING EX-PROGRAM PRODUCTS.

         7.5.1    Aventis hereby covenants to Millennium that (a) Aventis and
                  its Affiliates shall not research, Develop or Commercialize,
                  license any Third Party to research, Develop or Commercialize,
                  or provide any financial or other support to any Third Party
                  to enable such Third Party to research or conduct any clinical
                  study relating to the use of, any Ex-Program Product [**], and
                  Aventis shall impose such restriction on all its sublicensees
                  and distributors of Ex-Program Products.

         7.5.2    Millennium hereby covenants to Aventis that (a) Millennium and
                  its Affiliates shall not research, Develop or Commercialize,
                  license any Third Party to research, Develop or Commercialize,
                  or provide any financial or other support to any Third Party
                  to enable such Third Party to research or conduct any clinical
                  study relating to the use of, any Ex-Program Product [**], and
                  Millennium shall impose such restriction on all its
                  sublicensees and distributors of Ex-Program Products.

                                   ARTICLE 8

                              FINANCIAL PROVISIONS

8.1      EQUITY INVESTMENT. On the date hereof, Aventis and Millennium are
         entering into an Investment Agreement (the "Investment Agreement")
         pursuant to which, subject to the terms and conditions contained
         therein, Aventis shall purchase common stock of Millennium for an
         aggregate purchase price of Two Hundred Fifty Million Dollars
         ($250,000,000) at such times and at such per share prices as provided
         for in the Investment Agreement.


                                      Page 88

<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

8.2      PRE-TAX PROFIT OR LOSS IN NORTH AMERICA.

         8.2.1    PRE-TAX PROFIT OR LOSS. The Parties shall share equally in all
                  Pre-tax Profit or Loss. It is understood that costs and
                  expenses included in components of Pre-tax Profit or Loss
                  shall not be double counted. For clarity, (i) costs and
                  expenses included in any one of the component categories of
                  Pre-tax Profit or Loss shall not be included in any other
                  component categories of Pre-tax Profit or Loss, (ii) costs and
                  expenses included in any of the component categories of
                  pre-tax Profit or Loss shall not also be deductible under the
                  definition of Net Sales, (iii) deductions under the definition
                  of Net Sales shall not also be included as costs and expenses
                  in any of the component categories of Pre-tax Profit or Loss,
                  and (iv) costs incurred by a manufacturing Party and charged
                  under a supply agreement relevant for North America pursuant
                  to Section 4.3 shall not be separately included in the
                  calculation of Pre-tax Profit or Loss.

         8.2.2    QUARTERLY RECONCILIATION OF PRE-TAX PROFIT OR LOSS.

                  (a)      Within [**] days following the end of each calendar
                           quarter, Millennium shall submit to Aventis a written
                           report setting forth in reasonable detail, separately
                           with respect to each Joint Development Compound and
                           Joint Development Product, to the extent made or
                           incurred by Millennium (i) Net Sales of Joint
                           Development Products in North America, (ii) G&A
                           Expense, (iii) Supply Price of Joint Development
                           Product sold in North America, (iv) NA Period Costs,
                           (v) NA Commercialization Expense, (vi) NA Development
                           Cost, (vii) NA License Fees and (viii) NA/Ex-NA
                           Expense (including a breakdown of NA/Ex-NA Period
                           Costs, NA/Ex-NA Commercialization Expense, NA/Ex-NA
                           Development Cost and NA/Ex-NA License Fees, before
                           multiplication by the NA Percentage).

                  (b)      Within [**] days following the end of each calendar
                           quarter, Aventis shall submit to Millennium a written
                           report setting forth in reasonable detail, separately
                           with respect to each Joint Development Compound and
                           Joint Development Product, to the extent made or
                           incurred by Aventis (i) Net Sales of Joint
                           Development Products in North America, (ii) G&A
                           Expense, (iii) Supply Price of Joint Development
                           Product sold in North America, (iv) NA Period Costs,
                           (v) NA Commercialization Expense, (vi) NA Development
                           Cost, (vii) NA License Fees, and (viii) NA/Ex-NA
                           Expense (including a breakdown of NA/Ex-NA Period
                           Costs, NA/Ex-NA Commercialization Expense, NA/Ex-NA
                           Development Cost and NA/Ex-NA License Fees, before
                           multiplication by the NA Percentage).


                                      Page 89
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    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (c)      In performing the reconciliations contemplated by
                           Sections 8.2.2(a) and 8.2.2(b), costs and expenses
                           shall be submitted as part of NA Commercialization
                           Expense, NA Development Cost, NA License Fees,
                           NA/Ex-NA Commercialization Expense, NA/Ex-NA
                           Development Cost or NA/Ex-NA License Fees for
                           inclusion in the reconciliation of Pre-tax Profit or
                           Loss only to the extent made or incurred in
                           conjunction with an approved budget line item, as
                           approved and revised from time to time by the Joint
                           Development Committee or the relevant Joint
                           Commercialization Project Team or North America
                           Commercialization Project Team, as applicable.

                  (d)      Within [**] days following the end of each calendar
                           quarter, Millennium shall submit to Aventis a written
                           report setting forth in reasonable detail the
                           calculation of Pre-tax Profit or Loss and the
                           calculation of any net amount owed by Millennium to
                           Aventis or by Aventis to Millennium, as the case may
                           be, in order to ensure an equal sharing of Pre-tax
                           Profit of Loss. The net amount payable shall be paid
                           by Aventis or Millennium, as the case may be, within
                           [**] days after receipt of such written report,
                           without regard to any dispute as to the amounts under
                           this subsection 8.2.2(d); provided, that, in the
                           event of a dispute, the disputing Party shall provide
                           written notice within such [**] day period after
                           receipt of the written report in question, specifying
                           in detail such dispute. The Parties shall promptly
                           thereafter meet and negotiate in good faith a
                           resolution to such dispute. In the event that the
                           Parties are unable to resolve such dispute within
                           [**] days after notice by the disputing Party, the
                           matter shall be resolved in a manner consistent with
                           the procedures set forth in Article 12 (PROVIDED,
                           that, in the case that the matter has not been
                           resolved by the Executive Officers, such matter shall
                           be referred to an internationally recognized
                           independent accounting firm acceptable to both
                           Parties for non-binding resolution, rather than
                           to non-binding mediation under Section 12.5), and
                           interest shall be payable on any additional amounts
                           determined to be due in the same manner as provided
                           for in Section 8.8.

                  (e)      At least [**] days prior to the end of each calendar
                           quarter, Millennium shall submit to Aventis
                           reasonable estimates of the items listed in
                           subsection 8.2.2(a) and Aventis shall submit to
                           Millennium reasonable estimates of the items listed
                           in subsection 8.2.2(b), in order to allow the Parties
                           to comply with internal reporting requirements.


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                    Commission. Asterisks denote omissions.

         8.2.3    USE OF DATA DEVELOPED IN ROW. In the event that the Parties
                  wish to use for Development or Commercialization in North
                  America data, information, material or results relating to a
                  Joint Development Product which was generated and paid for
                  solely by Aventis, then Millennium would be required to
                  reimburse Aventis an amount equal to 50% of the arithmetic
                  average of (i) the NA Percentage and (ii) 100% of the costs
                  incurred by Aventis in generating such data, such costs to be
                  determined in a manner consistent with the manner in which NA
                  Development Cost is determined.

         8.2.4    USE OF DATA DEVELOPED FOR NORTH AMERICA. In the event that
                  Aventis wishes to use for Development or Commercialization in
                  ROW data, information, material or results relating to a Joint
                  Development Product which was paid for equally by Aventis and
                  Millennium (i.e., such costs were part of NA Development
                  Costs), then Aventis would be required to reimburse Millennium
                  an amount equal to (a) 0.75 times (b) 100% less the NA
                  Percentage of (c) the costs incurred by the Parties in
                  generating such data, information, materials or results, such
                  costs to be determined in a manner consistent with the manner
                  in which NA Development Cost is determined.

8.3      ROYALTIES.

         8.3.1    JOINT DEVELOPMENT PRODUCTS SOLD OUTSIDE OF NORTH AMERICA.
                  Aventis shall pay to Millennium royalties on Net Sales outside
                  of North America for each Joint Development Product as
                  follows:

<TABLE>

<CAPTION>

                  Annual Net Sales
                  LEVEL OUTSIDE OF NORTH AMERICA               ROYALTY RATE
<S>               <C>                                          <C>
                  [**]  million                                [**] %
                  Above [**]  million                          [**] %
                  Above [**]  million                          [**] %

</TABLE>


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                    Commission. Asterisks denote omissions.

         Royalties on Net Sales of each Joint Development Product in a calendar
         year shall be paid at the rate applicable to the portion of Net Sales
         within each of the Net Sales levels above during such calendar year.
         For example, if Net Sales in a given calendar year outside of North
         America for a Joint Development Product are $[**] million, then the
         royalty rate for the first $[**] million of such Net Sales would be
         [**] %, for such Net Sales in excess of $[**] million up to $[**]
         million would be [**] % and for such Net Sales in excess of $[**]
         million would be [**] %, for a total royalty payment under this example
         of $[**] million. Royalties shall be payable, on a country-by-country
         basis, for the longer of (a) the term of any patents Controlled by
         Aventis or Millennium with a Valid Claim Covering the composition of
         matter or therapeutic use of the Joint Development Product in such
         country or (b) [**] years after the First Commercial Sale of such Joint
         Development Product in such country. The royalties set forth above
         shall be subject to the following reductions: (x) from and after the
         expiration, invalidation, surrender or cancellation of the last patent
         Controlled by Aventis or Millennium with a Valid Claim Covering the
         composition of matter or therapeutic use of a Joint Development Product
         in a particular country, the royalty rate for sales of such Joint
         Development Product in such country for any remaining term in
         accordance with the preceding sentence shall be reduced by [**] %; (y)
         Aventis may deduct [**] of payments related to Burdened Technology
         Obligations relating to, and royalty payments made to Third Parties to
         obtain licenses to, patents Covering the composition of matter or
         therapeutic use of a Joint Development Product in a country; and (z) in
         countries other than ROW Major Market Countries where Aventis
         reasonably demonstrates to Millennium that a lower royalty is required
         in order to permit Aventis to Commercialize the Joint Development
         Product with a reasonable profit (it being understood and agreed that
         such demonstration shall be satisfied if Aventis' gross margin after
         royalty obligations with respect to such Joint Development Product is
         less than [**] % during any calendar year), the royalty rate for such
         calendar year under this subsection with respect to Net Sales of such
         Joint Development Product in such country shall be reduced to the
         extent necessary to enable Aventis to achieve such reasonable profit;
         provided that, notwithstanding the foregoing reductions, in no event
         shall the royalties received by Millennium under this subsection be
         less than [**] % of Net Sales. Net Sales of Related Joint Development
         Products (as defined below) shall be aggregated for purposes of
         determining Annual Net Sales Level Outside of North America in the
         above table. In the event that the royalty period specified above with
         respect to one of such Related Joint Development Products expires, then
         Net Sales of such Related Joint Development Product whose royalty
         period has expired thereafter shall not be counted into the Annual Net
         Sales Level Outside of North America in the above table for purposes of
         determining the applicable royalty rate under this subsection. As used
         above, a "Related Joint Development Product" means a Joint Development
         Product that contains as its sole active ingredient the same Joint
         Development Compound as


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         another Joint Development Product, PROVIDED THAT a Joint Development
         Product shall not constitute a Related Joint Development Product to
         another Joint Development Product if such Joint Development Product (i)
         is approved for a different disease state than such other Joint
         Development Product, (ii) requires a different package insert from such
         other Joint Development Product and (iii) has a different SKU from such
         other Joint Development Product.

         8.3.2    UNILATERAL DEVELOPMENT COMPOUND PRODUCTS. The Developing Party
                  shall pay royalties to the other Party on Net Sales of each
                  UDC Product as follows:

<TABLE>

<CAPTION>

                                                      OPT-OUT PHASE

                                                     From EDC Status
                                                up to but not including
                   Annual Worldwide                    Phase IIIA                      Phase IIIA
                   NET SALES LEVEL                     COMPLETION                  COMPLETION OR LATER
<S>               <C>                            <C>                               <C>
                  [**] million                           [**] %                          [**] %

                  Above [**] million                     [**] %                          [**] %

</TABLE>

         In the table above, "Opt-Out Phase" means the most advanced development
         phase of an EDC Compound when the other Party elected not to
         participate further in Development or Commercialization of such
         Unilateral Development Compound. Royalties on Net Sales of each UDC
         Product in a calendar year shall be paid at the rate applicable to the
         portion of Net Sales within each of the Net Sales levels above during
         such calendar year. Royalties shall be payable, on a country-by-country
         basis, for the longer of (a) the term of any patents Controlled by
         Aventis or Millennium with a Valid Claim Covering the composition of
         matter or therapeutic use of the UDC Product in such country or (b)
         [**] years after the First Commercial Sale of such UDC Product in such
         country. The royalties set forth above shall be subject to the
         following reductions: (x) from and after the expiration, invalidation,
         surrender or cancellation of the last patent Controlled by Aventis or
         Millennium with a Valid Claim Covering the composition of matter or
         therapeutic use of a UDC Product in a particular country, the royalty
         rate for sales of such UDC Product in such country for any remaining
         term in accordance with the preceding sentence shall be reduced by
         [**]%; (y) the Developing Party may deduct [**] of payments related to
         Burdened Technology Obligations relating to, and royalty payments made
         to Third Parties to obtain licenses to, patents Covering the
         composition of matter or therapeutic use of a UDC Product in a country;
         and (z) in countries other than the United States, Canada and the ROW
         Major Market Countries where the Developing Party reasonably
         demonstrates to the other Party that a lower royalty is required in
         order to permit the Developing Party to Commercialize the UDC Product
         with a reasonable profit (it being understood and agreed that such
         demonstration shall be satisfied if the Developing Party's gross
         margin after royalty obligations with respect to such


                                    Page 93

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                    Commission. Asterisks denote omissions.

         UDC Product is less than [**] % during any calendar year), the royalty
         rate for such calendar year under this subsection with respect to Net
         Sales of such UDC Product in such country shall be reduced to the
         extent necessary to enable the Developing Party to achieve such
         reasonable profit; provided that, notwithstanding the foregoing
         reductions, in no event shall the royalties received by the other Party
         under this subsection be less than [**] % of Net Sales. Net Sales of
         Related UDC Products (as defined below) shall be aggregated for
         purposes of determining Annual Net Sales Level worldwide in the above
         table. In the event that the royalty period specified above with
         respect to one of such Related UDC Products expires, then Net Sales of
         such Related UDC Product whose royalty period has expired thereafter
         shall not be counted into the Annual Net Sales Level worldwide in the
         above table for purposes of determining the applicable royalty rate
         under this subsection. As used above, a "Related UDC Product" means a
         UDC Product that contains as its sole active ingredient the same
         compound as another UDC Product, PROVIDED THAT a UDC Product shall not
         constitute a Related UDC Product to another UDC Product if such UDC
         Product (i) is approved for a different disease state than such other
         UDC Product, (ii) requires a different package insert from such other
         UDC Product, and (iii) has a different SKU from such other UDC Product.

         8.3.3    SINGLE-PARTY TARGET PRODUCTS. The Party that Commercializes a
                  Single-Party Target Product shall pay a royalty of [**] % of
                  Net Sales of such Single-Party Target Product to the other
                  Party. Royalties shall be payable, on a country-by-country
                  basis, for the longer of (a) the term of any patents
                  Controlled by Aventis or Millennium with a Valid Claim
                  Covering the composition of matter or therapeutic use of the
                  Single-Party Target Product in such country or (b) [**] years
                  after the First Commercial Sale of such Single-Party Target
                  Product in such country. The royalty rate set forth in this
                  subsection 8.3.3, and the royalties payable under this
                  subsection, shall not be subject to any reductions, deductions
                  or offsets of any kind.

         8.3.4    EX-PROGRAM PRODUCTS. The Party that Commercializes an
                  Ex-Program Product based upon an SQT Covered by any
                  intellectual property Controlled by the other Party shall pay
                  a royalty of [**] % of Net Sales of such Ex-Program Product to
                  the other Party. Royalties shall be payable, on a
                  country-by-country basis, for [**] years after the First
                  Commercial Sale of such Ex-Program Product in such country.
                  The royalty rate set forth in this subsection 8.3.4, and the
                  royalties payable under this subsection, shall not be subject
                  to any reductions, deductions or offsets of any kind.


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         8.3.5    GT OR VACCINE PRODUCTS. If Aventis elects to exercise a GT or
                  Vaccine Option with respect to a Program Target, Aventis shall
                  pay Millennium a royalty of [**]% of Net Sales of any
                  resulting GT or Vaccine Products. Royalties shall be payable,
                  on a country-by-country basis, for [**] years after the First
                  Commercial Sale of such GT or Vaccine Product in such country.
                  The royalty rate set forth in this subsection 8.3.5, and the
                  royalties payable under this subsection, shall not be subject
                  to any reductions, deductions or offsets of any kind.

         8.3.6    ANTIBODY PRODUCTS OR DIAGNOSTIC PRODUCTS OR SERVICES. If
                  Millennium elects to exercise an Antibody or Diagnostic Option
                  with respect to a Program Target, Millennium shall pay Aventis
                  a royalty of (a) [**] % of Net Sales of any resulting Antibody
                  Products, and (b) [**] % of any resulting Diagnostic Products
                  or Services. Royalties shall be payable, on a
                  country-by-country basis, for 14 years after the First
                  Commercial Sale of such Antibody Product or Diagnostic Product
                  or Service in such country. The royalty rate set forth in this
                  subsection 8.3.6, and the royalties payable under this
                  subsection, shall not be subject to any reductions, deductions
                  or offsets of any kind.

8.4      ROYALTY REPORTS; PAYMENTS. Within sixty (60) days after the end of each
         calendar quarter in which a Party is the Royalty-Paying Party with
         respect to Net Sales subject to any of the provisions of Section 8.3,
         such Party shall submit to the other Party a report, on the basis of
         each product and country, providing in reasonable detail an accounting
         of all Net Sales made during such calendar quarter and the calculation
         of the applicable royalty under Section 8.3. Concurrently with such
         report, the Royalty-Paying Party submitting the report shall pay to the
         other Party all royalties payable by it under Section 8.3 as indicated
         in the report.

8.5      AUDITS. Each Party shall keep complete and accurate records of the
         underlying revenue and expense data relating to the reports and
         payments required by Sections 8.2 and 8.4. Each Party will have the
         right once annually at its own expense to have an independent,
         certified public accountant, selected by such Party and reasonably
         acceptable to the other Party, review any such records of the other
         Party in the location(s) where such records are maintained by the other
         Party upon reasonable notice and during regular business hours and
         under obligations of strict confidence, for the sole purpose of
         verifying the basis and accuracy of payments made under Sections 8.2
         and 8.4, in each case within the prior twenty-four (24) month period.
         If the review of such records reveals that the other Party has failed
         to accurately report information pursuant to Section 8.2 or Section
         8.4, then the other Party shall promptly pay to the auditing Party any
         resulting amounts due under Section 8.2 or Section 8.4, together with
         interest calculated in the manner provided in Section 8.8. If any
         amounts due under Section 8.2 or


                                    Page 95
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         Section 8.4 as a result of such audit are greater than five percent
         (5%) of the amounts actually due for a calendar year under Section 8.2
         or Section 8.4, as applicable, the other Party shall pay all of the
         costs of such review. If a Party in good faith disputes any conclusion
         of the accounting firm under this Section 8.5, including that such
         Party owes additional amounts, then such Party shall inform the other
         Party by written notice within thirty (30) days of receipt of a copy of
         the audit in question, specifying in detail such dispute. The Parties
         shall promptly thereafter meet and negotiate in good faith a resolution
         to such dispute. In the event that the Parties are unable to resolve
         such dispute within sixty (60) days after notice by the disputing
         Party, the matter shall be resolved in a manner consistent with the
         procedures set forth in Article 12 (provided, that, in the case that
         the matter has not been resolved by the Executive Officers, such matter
         shall be referred to an internationally recognized independent
         accounting firm acceptable to both Parties for rather than non-binding
         mediation under Section 12.5), and interest shall be payable on any
         additional amounts determined to be due in the same manner as provided
         for in Section 8.8.

8.6      TAX MATTERS.

         8.6.1    Any income or other taxes which a paying Party is required by
                  law to pay or withhold on behalf of a receiving Party with
                  respect to royalties or other payments payable to a receiving
                  Party under this Agreement shall be deducted from the amount
                  of such royalties or other payments due, and paid or withheld,
                  as appropriate, by the paying Party on behalf of the receiving
                  Party. Any such tax required by law to be paid or withheld
                  shall be an expense of, and borne solely by, the receiving
                  Party. The paying Party shall furnish the receiving Party with
                  reasonable evidence of such payment or amount withheld, in
                  electronic or written form, as soon as practicable after such
                  payment is made or such amount is withheld. The Parties will
                  reasonably cooperate in completing and filing documents
                  required under the provisions of any applicable tax laws or
                  under any other applicable law in connection with the making
                  of any required tax payment or withholding payment, or in
                  connection with any claim to a refund of or credit for any
                  such payment.

         8.6.2    The Parties shall work together with respect to each Joint
                  Development Product to determine the appropriate structure for
                  the sharing of Pre-tax Profit or Loss in Canada, based on the
                  respective roles of the Parties in the Commercialization
                  activities, including without limitation distribution and
                  manufacturing. Such structuring shall conform to the
                  principles described in Section 8.2.

8.7      CURRENCY EXCHANGE. With respect to Net Sales invoiced or expenses
         incurred in U.S. dollars, the Net Sales or expense amounts and the
         amounts due to the receiving Party hereunder shall be expressed in U.S.
         dollars. With respect to Net Sales invoiced or expenses incurred in a
         currency other than U.S. dollars, the Net Sales or expense shall be
         expressed in the domestic currency of the entity making


                                    Page 96
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         the sale or incurring the expense, together with the U.S. dollar
         equivalent, calculated using the arithmetic average of the spot rates
         on the last business day of each month of the calendar quarter in which
         the Net Sales were made or the expense was incurred. The "closing
         mid-point rates" found in the "dollar spot forward against the dollar"
         table published by THE FINANCIAL TIMES or any other publication as
         agreed to by the Parties shall be used as the source of spot rates to
         calculate the average as defined in the preceding sentence. All
         payments shall be made in U.S. dollars. If at any time legal
         restrictions in any country in the Territory prevent the prompt
         remittance of any payments with respect to sales in that country, the
         paying Party shall have the right and option to make such payments by
         depositing the amount thereof in local currency to the receiving
         Party's account in a bank or depository in such country.

8.8               LATE PAYMENTS. The paying Party shall pay interest to the
                  receiving Party on the aggregate amount of any payments that
                  are not paid on or before the date such payments are due under
                  this Agreement at a rate per annum equal to the lesser of the
                  prime rate of interest plus one percent (1%), as reported by
                  THE WALL STREET JOURNAL, or the highest rate permitted by
                  applicable law, calculated on the number of days such payments
                  are paid after the date such payments are due.

                                   ARTICLE 9

         INTELLECTUAL PROPERTY OWNERSHIP, PROTECTION AND RELATED MATTERS

9.1      OWNERSHIP.

         9.1.1    INVENTIONS. Inventorship for patentable inventions conceived
                  or reduced to practice during the course of the performance of
                  activities pursuant to this Agreement shall be determined in
                  accordance with U.S. patent laws for determining inventorship.
                  Subject to the provisions set forth in Section 9.1.2,
                  ownership shall be initially determined based on inventorship.
                  In the event of a dispute regarding inventorship, if the
                  Parties are unable to resolve such inventorship dispute, the
                  Joint Steering Committee shall establish a procedure to
                  resolve such dispute, which may include engaging a Third Party
                  patent attorney jointly selected by the Parties to resolve
                  such dispute.


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         9.1.2    ASSIGNMENT OF OWNERSHIP.

                  (a)      TARGET RELATED INVENTIONS. In the event a Party [**]
                           in the conduct of the Research Program and [**], then
                           such Party or Parties, as the case may be, shall [**]
                           to the Party or Parties, if any, [**] to the Research
                           Program pursuant to Section 2.7.1(b).

                  (b)      COMPOUND RELATED INVENTIONS. In the event a Party
                           [**] in the conduct of the Research Program [**] then
                           the Party or Parties, as the case may be, shall [**]
                           to the Party or Parties, if any, [**].

9.2      PROSECUTION AND MAINTENANCE OF PATENT RIGHTS.

         9.2.1    The responsibility for (a) preparing, filing and prosecuting
                  patent applications (including reissue, continuing,
                  divisional, and substitute applications and any foreign
                  counterparts thereof); (b) for maintaining any Patent Rights;
                  and (c) for managing any interference or opposition
                  proceedings relating to the foregoing ("Patent Prosecution")
                  Covering an invention conceived or reduced to practice during
                  the course of the performance of activities pursuant to this
                  Agreement shall be the responsibility of the Party owning such
                  invention, PROVIDED, HOWEVER, that with respect to any such
                  invention that is jointly owned by the Parties, such
                  responsibility shall be shared by the Parties as determined by
                  agreement of the Parties on a case-by-case basis. All Patent
                  Prosecution expenses, including attorneys' fees, incurred by a
                  Party in the performance of Patent Prosecution shall be borne
                  by such Party or, in the case of an invention that is jointly
                  owned, shared by the Parties as agreed.

         9.2.2    SECONDARY PROSECUTION RIGHTS. If the prosecuting Party elects
                  not to continue pursuing Patent Prosecution with respect to
                  any rights within Patent Rights (and the other Party has
                  rights under such Patent Right), then the prosecuting Party
                  shall, subject to any contractual obligations to Third
                  Parties, notify the other Party in writing of such election at
                  least thirty (30) days prior to the last available date for
                  action to preserve such Patent Rights. If such other Party
                  elects to continue Patent Prosecution, such other Party may do
                  so at its sole expense.

9.3      COOPERATION.  Each Party hereby agrees

         9.3.1    to make its employees, agents and consultants reasonably
                  available to the other Party (or to the other Party's
                  authorized attorneys, agents or representatives), to the
                  extent reasonably necessary to enable the prosecuting Party to
                  undertake Patent Prosecution,


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         9.3.2    to provide the other Party with copies of all material
                  correspondence pertaining to Patent Prosecution with the U.S.
                  Patent and Trademark Office or its foreign counterparts;

         9.3.3    to cooperate, if necessary and appropriate, with the other
                  Party in gaining patent term extensions wherever applicable to
                  Patent Rights; and

         9.3.4    to endeavor in good faith to coordinate its efforts with the
                  other Party to minimize or avoid interference with the Patent
                  Prosecution of the other Party's patent applications.

9.4      EXPLOITATION OF JOINT INVENTIONS. Subject to any provision of this
         Agreement to the contrary, each of the Parties shall be free to exploit
         any invention conceived or reduced to practice during the course of the
         performance of activities pursuant to this Agreement and that is
         jointly owned by the Parties without payment of any additional
         compensation to the other Party; PROVIDED, HOWEVER, that either Party
         may only sell, license or otherwise transfer its rights in any such
         invention without the consent of the other Party in a manner that is
         consistent with the licenses granted pursuant to this Agreement and is
         otherwise consistent with this Agreement.

9.5      THIRD PARTY INFRINGEMENT.

         9.5.1    NOTICE. Each Party shall promptly provide, but in on event
                  later than [**], the other with written notice reasonably
                  detailing any known or alleged infringement of the other
                  Party's Program Patent Rights by a Third Party.

         9.5.2    JOINT DEVELOPMENT PRODUCTS.

                  (a)      In North America each Party shall have the sole
                           right, but not the obligation, to institute and
                           direct legal proceedings against any Third Party
                           believed to be infringing the Patent Rights of such
                           Party ("Owing Party"), that Covers an invention that
                           relates to a Joint Development Product; PROVIDED,
                           HOWEVER, that the Parties shall mutually agree on a
                           course of action for instituting and directing legal
                           proceedings against any Third Party believed to be
                           infringing any such Patent Rights that are jointly
                           owned by the Parties. If the Owning Party, within
                           [**] of a notice of infringement pursuant to Section
                           9.5.1, has not taken action with respect to a Third
                           Party, the other Party may request consent from the
                           Owning Party to institute and direct legal
                           proceedings against such Third Party, including in
                           the name of the Owning Party, which consent shall not
                           be unreasonably withheld. The Owning Party shall
                           respond to such request within [**] of receipt of
                           such


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                    Commission. Asterisks denote omissions.

                           request in writing. All costs, including attorneys'
                           fees, relating to such legal proceedings shall be
                           borne by the Party that owns such Patent Rights or,
                           in the case of Patent Rights that are jointly owned,
                           shared by the Parties as agreed by the Parties. If
                           the Parties share the expense, the recoveries shall
                           be divided between the Parties in proportion with
                           their contribution to the expenses. If only one Party
                           is bearing the expense, then the Party not bearing
                           any of the expense shall receive [**] of the all
                           recoveries directed to compensatory damages and [**]
                           of all recoveries directed to punitive or other
                           damages in excess of such Party's costs, including
                           attorney's fees.

                  (b)      Outside North America, Aventis shall have the sole
                           right, but not the obligation, to institute legal
                           proceedings against any Third Party believed to be
                           infringing the Patent Rights of either Party that
                           Cover an invention that relates to a Joint
                           Development Product. All costs, including attorneys'
                           fees, relating to such legal proceedings shall be
                           borne by Aventis. All recoveries resulting from such
                           legal proceedings that are in excess of Aventis'
                           cost, including attorney's fees, shall be deemed to
                           be Ex-NA Net Sales of such Joint Development Product.

         9.5.3    OTHER PROGRAM PATENT RIGHTS. Each Party shall have the sole
                  right, but not the obligation, to institute and direct legal
                  proceedings against any Third Party believed to be infringing
                  the Program Patent Rights of such Party that do not Cover an
                  invention that relates to a Joint Development Product,
                  PROVIDED, HOWEVER, that the Parties shall mutually agree on a
                  course of action for instituting and directing legal
                  proceedings against any Third Party believed to be infringing
                  any such Program Patent Rights that are jointly owned by the
                  Parties. All costs, including attorneys' fees, or recoveries
                  relating to such legal proceedings shall be borne by the Party
                  that owns such Program Patent Rights or, in the case of
                  Program Patent Rights that are jointly owned, shall be shared
                  by the Parties as agreed. All recoveries resulting from such
                  legal proceeding in excess of the Party's or Parties' costs,
                  including attorneys' fees, shall be deemed to be Net Sales of
                  the applicable Royalty-Bearing Product.


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         9.5.4    FAILURE TO INSTITUTE PROCEEDINGS. With respect to Program
                  Patent Rights which are solely owned by a Party ("Non-Selling
                  Party") Covering a UDC Product, a Single-Party Target Product,
                  GT Product, a Vaccine Product, an Antibody Product or a
                  Diagnostic Product or Service sold or provided by the other
                  Party ("Selling Party"), if the Non-Selling Party, within [**]
                  of a notice of infringement from the Selling Party pursuant to
                  Section 9.5.1, has not taken action pursuant to Sections 9.5.2
                  or 9.5.3 with respect to a Third Party that is selling a
                  product or providing a service in competition with such
                  Selling Party's product or service, such Selling Party may
                  request consent from the Non-Selling Party to institute such
                  legal proceedings, including in the name of the Non-Selling
                  Party, which consent shall not be unreasonably withheld. The
                  Non-Selling Party shall respond to such request within [**] of
                  receipt of such request in writing. All costs, including
                  attorneys' fees, relating to such legal proceedings shall be
                  borne by the Selling Party. Any recoveries in excess of costs
                  incurred by the Selling Party in pursuing any such legal
                  proceedings ("Excess Recovery") shall belong to the Selling
                  Party; PROVIDED, HOWEVER, that the Selling Party shall pay to
                  the Non-Selling Party the amount of any royalty that would be
                  due to the Non-Selling Party if such Excess Recovery had been
                  Net Sales made by the Selling Party of such Selling Party's
                  product.

         9.5.5    COOPERATION IN PATENT INFRINGEMENT PROCEEDINGS. In the event
                  that either Aventis or Millennium takes action pursuant to
                  this Section 9.5, the other Party shall cooperate to the
                  extent reasonably necessary and at the first Parties' sole
                  expense. Upon the reasonable request of the first Party, such
                  other Party shall join the suit and shall be represented in
                  any such legal proceedings using counsel of its own choice.
                  Neither Party shall settle any claim or proceeding relating to
                  Program Patent Rights owned in whole or in part by the other
                  Party without the prior written consent of such other Party,
                  which consent shall not be unreasonably withheld.

9.6      OTHER INTELLECTUAL PROPERTY INFRINGEMENT.

         9.6.1    NOTICE.

                  (a)      Each Party shall notify the other in writing of any
                           allegations it receives from a Third Party that
                           Program Technology, Program Materials or any
                           Royalty-Bearing Product infringes the intellectual
                           property rights of such Third Party. Such notice
                           shall be provided promptly, but in no event after
                           more than [**], following receipt of such allegations


                                    Page 101
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

                  (b)      In the event that a Party receives notice that it or
                           any of its Affiliates have been individually named as
                           a defendant in a legal proceeding by a Third Party
                           alleging infringement of a Third Party patent or
                           other intellectual property right as a result of the
                           manufacture, production, use, development, sale or
                           distribution of Program Technology, Program Materials
                           or Royalty-Bearing Product, such Party shall
                           immediately notify the other Party in writing and in
                           no event notify them later than [**] after the
                           receipt of such notice. Such written notice shall
                           include a copy of any summons or complaint (or the
                           equivalent thereof) received regarding the foregoing.

                  (c)      Each Party shall provide to the other Party copies of
                           any allegations of alleged patent invalidity or
                           non-infringement of a patent or patents with respect
                           to Program Technology, Program Materials or
                           Royalty-Bearing Product pursuant to a Paragraph IV
                           Patent Certification by a Party filing an Abbreviated
                           New Drug Application. Such copies shall be provided
                           promptly, but in any event within [**], of receipt of
                           such certification.

                  (d)      Each Party shall provide to the other Party copies of
                           any notices it receives from Third Parties regarding
                           any patent nullity actions, any declaratory judgment
                           actions, any alleged infringement of Program Patent
                           Rights or any alleged misappropriation of
                           intellectual property with respect to Program
                           Technology, Program Materials or Royalty-Bearing
                           Product. Such notices shall be provided promptly, but
                           in no event after more than [**], following receipt
                           thereof.

         9.6.2    In all cases where a claim is made by a Third Party and for
                  which notice was given in accordance with Section 9.6.1(c),
                  the Parties shall cooperate and the Party owning the NDA for
                  the Joint Development Product at issue shall determine the
                  appropriate course of action in consultation with the Party
                  not owning the NDA for such Joint Development Product. In all
                  cases where a claim is made by a Third Party and for which
                  notice was given in accordance with Section 9.6.1(a), (b) or
                  (d), the Parties shall cooperate and mutually determine a
                  course of action. In both of the foregoing, the Parties shall
                  share the expenses equally. If such claim is against only one
                  Party with respect to a Unilateral Development Compound, a UDC
                  Product, a Single-Party Target Product, a GT Product, a
                  Vaccine Product, an Antibody Product, a Diagnostic Product or
                  Service or an Ex-Program Product such Party shall have sole
                  discretion in determining and executing an appropriate course
                  of action at its sole expense.


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

9.7      MARKS FOR JD PRODUCTS.

         9.7.1    [**] shall also [**] shall [**] under this Section 9.7 [**].

         9.7.2    Aventis shall grant to Millennium a license to such Marks
                  solely for the purposes of performing its obligations and
                  exercising its rights relating to the Development and
                  Commercialization of a JD Product in North America. Such
                  license shall be exclusive with respect to use of the Marks in
                  a country in North America in connection with the distribution
                  of JD Products in such country that Millennium has the right
                  to distribute.

         9.7.3    Except as expressly stated in this Agreement, Millennium shall
                  not have any right, title, interest or other license in or to
                  any of the Marks, and all uses of such Marks shall inure
                  solely to the benefit of Aventis.

         9.7.4    Each Party agrees not to contest the validity of, by act or
                  omission jeopardize, or take any action inconsistent with, the
                  other Party's rights or goodwill in any of its Marks in any
                  country, including, without limitation, attempted registration
                  of any such Mark, or use or attempted registration of any
                  confusingly similar names, trademarks or logos.

         9.7.5    In the event that either Party becomes aware of any
                  infringement of a Mark in North America by a Third Party, it
                  shall promptly notify the other and the Parties shall consult
                  with each other and jointly determine the best way to prevent
                  such infringement, including without limitation by the
                  institution of legal proceedings against such Third Party. To
                  the extent that the Parties agree that Millennium shall be
                  responsible for instituting legal proceedings against a Third
                  Party and Millennium does not have the right under applicable
                  law to bring such legal proceedings in its own name, then
                  Aventis shall provide Millennium with such authorizations to
                  institute legal proceedings in Aventis' name. All costs,
                  including attorneys' fees, relating to such legal proceedings
                  shall be borne by the Party that institutes such proceedings
                  or shall be shared by the Parties as agreed and shall be
                  included in NA Marketing Expense. All recoveries resulting
                  from such legal proceedings shall be deemed to be Net Sales of
                  the Joint Development Product with which the infringed Mark is
                  used.


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<PAGE>


                                   ARTICLE 10

                                 CONFIDENTIALITY

10.1     CONFIDENTIAL INFORMATION. All Confidential Information disclosed by a
         Party to the other Party during the term of this Agreement shall not be
         used by the receiving Party except in connection with the activities
         contemplated by this Agreement, shall be maintained in confidence by
         the receiving Party and shall not otherwise be disclosed by the
         receiving Party to any other person, firm, or agency, governmental or
         private (other than a Party's Affiliates), without the prior written
         consent of the disclosing Party, except to the extent that the
         Confidential Information (as determined by competent documentation):

         10.1.1   was known or used by the receiving Party or its Affiliates
                  prior to its date of disclosure to the receiving Party; or

         10.1.2   either before or after the date of the disclosure to the
                  receiving Party is lawfully disclosed to the receiving Party
                  or its Affiliates by sources other than the disclosing Party
                  rightfully in possession of the Confidential Information; or

         10.1.3   either before or after the date of the disclosure to the
                  receiving Party or its Affiliates becomes published or
                  generally known to the public (including information known to
                  the public through the sale of products in the ordinary course
                  of business) through no fault or omission on the part of the
                  receiving Party, its Affiliates or its sublicensees; or

         10.1.4   is independently developed by or for the receiving Party or
                  its Affiliates without reference to or reliance upon the
                  Confidential Information.

                  In addition, the provisions of this Section 10.1 shall not
                  preclude the receiving Party or its Affiliates from disclosing
                  Confidential Information to the extent such Confidential
                  Information is required to be disclosed by the receiving Party
                  or its Affiliates to comply with applicable laws, to defend or
                  prosecute litigation or to comply with governmental
                  regulations, provided that the receiving Party provides prior
                  written notice of such disclosure to the disclosing Party and
                  takes reasonable and lawful actions to avoid and/or minimize
                  the degree of such disclosure. Specific information shall not
                  be deemed to be within any of the foregoing exclusions merely
                  because it is embraced by more general information falling
                  within these exclusions.

10.2     EMPLOYEE AND ADVISOR OBLIGATIONS. Millennium and Aventis each agree
         that they shall provide Confidential Information received from the
         other Party only to their respective employees, consultants and
         advisors, and to the employees, consultants and advisors of such
         Party's Affiliates, who have a need to know and have an obligation to
         treat such information and materials as confidential.


                                    Page 104
<PAGE>


10.3     TERM. All obligations of confidentiality imposed under this Article 10
         shall expire five (5) years following termination or expiration of this
         Agreement.

10.4     PUBLICATIONS. Neither Party nor its Affiliates shall publish or present
         the results of the Research Program or clinical studies on any Joint
         Development Compound or Joint Development Product until after
         completion of a Phase I Study with respect thereto. Subject to the
         foregoing and the restrictions provided below, either Party may publish
         or present the results of the Research Program or of Development
         carried out on such Joint Development Compound or Joint Development
         Product, subject to the prior review by the other Party for
         patentability and protection of such other Party's Confidential
         Information. Each Party shall provide to the other Party the
         opportunity to review any proposed abstracts, manuscripts or summaries
         of presentations which cover the results of the Research Program or of
         the Development of such Joint Development Compound or Joint Development
         Product. Each Party shall designate a person who shall be responsible
         for approving such publications. Such designated person shall respond
         in writing promptly and in no event later than sixty (60) days after
         receipt of the proposed material with either approval of the proposed
         material or a specific statement of concern, based upon either the need
         to seek patent protection or concern regarding competitive disadvantage
         arising from the proposal. In the event of concern, the submitting
         Party agrees not to submit such publication or to make such
         presentation that contains such information until the other Party is
         given a reasonable period of time (not to exceed ninety (90) days) to
         seek patent protection for any material in such publication or
         presentation which it believes is patentable or to resolve any other
         issues. With respect to any proposed abstracts, manuscripts or
         summaries of presentations by investigators or other Third Parties,
         such materials shall be subject to review under this Section 10.4 to
         the extent that Aventis or Millennium (as the case may be) has the
         right to do so.

                                   ARTICLE 11

                              TERM AND TERMINATION

11.1     TERM; EXTENSION. This Agreement becomes effective as of the Effective
         Date and may be terminated as set forth in this Article 11. The Parties
         acknowledge that they may find it to be mutually beneficial to continue
         the Research Program after the end of the Research Program Term.
         Consequently, the Parties hereby agree to negotiate in good faith,
         prior to six (6) months before the end of the Research Program Term,
         whether or not to extend the Research Program Term on terms and
         conditions that are mutually acceptable to the Parties. Should the
         Parties choose to extend the Research Program, they may choose to limit
         such extension to ongoing collaboration with respect to particular
         targets, compounds or products, or otherwise.



                                    Page 105
<PAGE>


11.2     TERMINATION FOR MATERIAL BREACH.

         11.2.1   TERMINATION RIGHTS. Upon a material breach of this Agreement
                  by Aventis or Millennium (in such capacity, the "Breaching
                  Party"), the other Party (in such capacity, the "Non-Breaching
                  Party") may provide written notice (a "Breach Notice") to the
                  Breaching Party specifying the material breach. If (i) the
                  Breaching Party fails to cure such material breach during the
                  sixty (60) day period (or, if such material breach, by its
                  nature, is a curable breach that is not curable within the
                  sixty (60) day period, such longer period as would be
                  reasonably necessary for a diligent party to cure such
                  material breach) following the date on which the Breach Notice
                  is provided, or (ii) such material breach, by its nature, is
                  incurable, then the Agreement shall terminate. The Parties
                  shall use reasonable efforts to work together to cure any
                  breach.

         11.2.2   MATERIAL BREACH RELATING TO THE RESEARCH PROGRAM.
                  Notwithstanding the provisions of Section 11.2.1, if the
                  material breach relates to the Breaching Party's obligations
                  under the Research Program, then only the Research Program
                  shall terminate.

         11.2.3   MATERIAL BREACH RELATING TO EXCLUSIVITY PROVISIONS.
                  Notwithstanding the provisions of Section 11.2.1, if the
                  material breach relates to the Breaching Party's obligations
                  under Section 2.8, the other Party may terminate any of the
                  covenants set forth in Sections 2.8.1 and 2.8.2 as it applies
                  to such Party, as one of its remedies and not to the exclusion
                  of any other remedy such Party may have.

         11.2.4   MATERIAL BREACH RELATING TO THE DEVELOPMENT OR
                  COMMERCIALIZATION OF CERTAIN ROYALTY-BEARING PRODUCTS.
                  Notwithstanding the provisions of Section 11.2.1, if the
                  material breach relates to the Breaching Party's obligations
                  relating to the Development or Commercialization of a
                  Royalty-Bearing Product (other than a Joint Development
                  Product), then the licenses granted to the Breaching Party
                  under this Agreement with respect to the Development and
                  Commercialization of such Royalty-Bearing Product shall
                  terminate and this Agreement shall not otherwise terminate;
                  provided that if this Agreement would terminate but for the
                  immediately preceding clause, then the Breaching Party hereby
                  grants to the Non-Breaching Party a worldwide, exclusive (even
                  as to the Breaching Party), non-royalty bearing, perpetual
                  license to the sole or undivided one half (as applicable)
                  right, title and interest in the Patent Rights of the
                  Breaching Party directly relating to such Royalty Bearing
                  Product and previously assigned by the Non-Breaching Party to
                  the Breaching Party pursuant to Section 9.1.2.

         11.2.5   MATERIAL BREACH RELATING TO THE DEVELOPMENT OR
                  COMMERCIALIZATION OF A JOINT DEVELOPMENT COMPOUND OR A JOINT
                  DEVELOPMENT PRODUCT. Notwithstanding the provisions of Section
                  11.2.1, if the material breach


                                    Page 106
<PAGE>


                  relates to the Breaching Party's obligations relating to the
                  Development and/or Commercialization of a Joint Development
                  Compound and/or a Joint Development Product, including without
                  limitation a material breach in the exercise of commercially
                  reasonable efforts to undertake Development and/or
                  Commercialization of such Joint Development Compound and/or
                  Joint Development Product, then this Agreement shall not
                  terminate in its entirety, but the licenses granted to the
                  Breaching Party under this Agreement with respect to the
                  Development and Commercialization of such Joint Development
                  Compound and/or Joint Development Product shall terminate;
                  PROVIDED, HOWEVER, that if such material breach relates solely
                  to the Breaching Party's obligations relating to the
                  Development and/or Commercialization of a Joint Development
                  Compound and/or a Joint Development Product in ROW, including
                  without limitation a material breach in the exercise of
                  commercially reasonable efforts to undertake such Development
                  and/or Commercialization, then only the licenses granted to
                  the Breaching Party under this Agreement with respect to
                  (i) the Development of such Joint Development Compound and/or
                  Joint Development Product for Commercialization in ROW and
                  (ii) Commercialization of such Joint Development Product in
                  ROW, shall terminate. Notwithstanding the foregoing, the
                  licenses to the Breaching Party shall terminate pursuant
                  to this subsection only if the Non-Breaching Party agrees
                  to use commercially reasonable efforts to continue the
                  worldwide (or, in the case of a material breach that relates
                  solely to the Breaching Party's obligations relating to the
                  Development and/or Commercialization of a Joint Development
                  Compound and/or a Joint Development Product in ROW, ROW-wide)
                  Development and Commercialization of the Joint Development
                  Compound and/or Joint Development Product as a Unilateral
                  Development Compound and/or Unilateral Development Product,
                  as the case may be, under this Agreement, in which case such
                  Joint Development Compound and/or Joint Development Product
                  shall for all purposes under this Agreement, including
                  (subject to the immediately following sentence) the payment
                  of royalties, be deemed a Unilateral Development Compound
                  and/or Unilateral Development Product, as the case may be
                  and the Non-Breaching Party shall for purposes of Section 3.7
                  be deemed the Developing Party. If the Non-Breaching Party
                  continues the ROW-wide Development and Commercialization of a
                  Joint Development Compound and/or Joint Development Product
                  as a Unilateral Development Compound and/or Unilateral
                  Development Product, as the case may be, pursuant to this
                  subsection, then the Non-Breaching Party shall be required to
                  pay royalties with respect to Net Sales of such Unilateral
                  Development Product in ROW at the same rate that Aventis
                  would be required to pay royalties on such Net Sales under
                  Section 8.3.1 if Aventis were the Commercializing Party and
                  such Unilateral Development Product were a Joint Development
                  Product.


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<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         11.2.6   MATERIAL BREACH OF INVESTMENT AGREEMENT. If Aventis commits a
                  material breach of its obligations to purchase common stock of
                  Millennium under the Investment Agreement and does not cure
                  such breach within [**] after written notice thereof by
                  Millennium, then Millennium may terminate the licenses granted
                  under this Agreement to Aventis and upon any termination under
                  this Section 11.2.6, the Breaching Party hereby grants to the
                  Non-Breaching Party a worldwide, exclusive (even as to the
                  Breaching Party), non-royalty-bearing, perpetual license under
                  the sole or undivided one-half (as applicable) right, title
                  and interest of the Non-Breaching Party in all intellectual
                  property rights assigned to the Breaching Party pursuant to
                  Section 9.1.2, for all purposes.

11.3     TERMINATION UPON HSR DENIAL. The Agreement shall immediately terminate
         in the event that either (a) the FTC and/or the DOJ shall seek a
         preliminary injunction under the HSR Act against Millennium and Aventis
         to enjoin the transactions contemplated by this Agreement, the
         Technology Development Agreement, the Technology Transfer Agreement
         and/or the Investment Agreement, or (b) the HSR Clearance Date shall
         not have occurred on or prior to December 31, 2000. Notwithstanding
         the foregoing, this Section 11.3 shall not apply in the event the
         Parties mutually agree that an HSR Filing is not required.

11.4     DISPUTE RESOLUTION. Termination under this Article for whatever reason
         will be automatically stayed for the duration of any dispute resolution
         proceedings initiated under Article 12.

11.5     RESIDUAL RIGHTS. Upon termination of this Agreement, except as
         specifically provided herein to the contrary, all rights and
         obligations of the Parties under this Agreement shall cease, except as
         follows:

         11.5.1   Obligations to pay amounts accruing hereunder up to the date
                  of termination;

         11.5.2   The obligations regarding confidentiality as set forth in
                  Article 10;

         11.5.3   All obligations for record keeping and accounting reports;

         11.5.4   The Parties' right to inspect books and records of each other
                  as set forth in Section 8.5;

         11.5.5   The Parties' rights with respect to the ownership of
                  intellectual property as set forth in Article 9; and

         11.5.6   Obligations of defense and indemnity, which obligations shall
                  continue in full force and effect for an unlimited period.


                                    Page 108
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                                   ARTICLE 12

                               DISPUTE RESOLUTION

12.1     JOINT STEERING COMMITTEE.

         12.1.1   As soon as practicable after the Execution Date, Aventis and
                  Millennium shall establish a Joint Steering Committee
                  comprised of three (3) senior executives of Aventis and three
                  (3) senior executives of Millennium.

         12.1.2   The Joint Steering Committee shall meet at least four times
                  annually to (a) review the efforts of the Parties in the
                  conduct of the Research Program and Development and
                  Commercialization activities, and (b) attempt to resolve any
                  disputes relating to this Agreement that may arise between the
                  Parties that are referred to the Joint Steering Committee by
                  the Joint Research Committee, Joint Development Committee or
                  Joint Commercialization Committee or either of the Parties.

         12.1.3   The location of such meetings of the Joint Steering Committee
                  shall be as agreed by the Parties. The Joint Steering
                  Committee may also meet by means of a telephone conference
                  call or by videoconference.

         12.1.4   Each Party may change any one or more of its representatives
                  to the Joint Steering Committee at any time upon written
                  notice to the other Party.

         12.1.5   Each Party shall use commercially reasonable efforts to cause
                  its representatives to attend the meetings of the Joint
                  Steering Committee. If a representative of a Party is unable
                  to attend a meeting, such Party may designate an alternative
                  to attend such meeting in place of the absent representative,
                  and such alternate shall have full voting power at such
                  meeting.

         12.1.6   In addition, each Party may, at its discretion, invite
                  non-voting employees, and, with the consent of the other
                  Party, consultants or scientific advisors, to attend meetings
                  of the Joint Steering Committee.

         12.1.7   Decisions of the Joint Steering Committee shall be made by
                  unanimous consent of Aventis and Millennium, with each Party
                  having one vote. Either Party may convene a special meeting of
                  the Joint Steering Committee for the purpose of resolving
                  disputes.

12.2     REFERRAL OF UNRESOLVED MATTERS TO JOINT STEERING COMMITTEE. If the
         Joint Research Committee, Joint Development Committee or a Joint
         Commercialization Committee is unable to reach a decision on any matter
         within the scope of its responsibilities within thirty (30) days after
         such matter is first considered by it, either Party may refer such
         unresolved matter to the Joint Steering Committee for consideration and
         resolution. Unresolved matters pertaining to intellectual property
         matters shall be governed by Article 9. In such


                                    Page 109
<PAGE>


         event, a meeting of the Joint Steering Committee shall be convened as
         soon as practicable in order to consider and resolve the unresolved
         matter. Any determination by the Joint Steering Committee shall be
         final and binding upon the Parties.

12.3     REFERRAL OF UNRESOLVED MATTERS TO EXECUTIVE OFFICERS. If the Joint
         Steering Committee is unable to resolve any matter referred to it under
         Section 12.2 within thirty (30) days after the matter is referred to
         it, the matter shall be referred to the Executive Officers to be
         resolved by negotiation in good faith as soon as is practicable but in
         no event later than thirty (30) days after referral. Such resolution,
         if any, of a referred issue by the Executive Officers shall be final
         and binding on the Parties.

12.4     INDEPENDENT EXPERTS. Each Executive Officer shall have the right to
         engage the services of any number of independent experts in the field
         in question (the individual(s) so engaged by each Executive Officer to
         be engaged under obligations of confidentiality) to assist the
         Executive Officer in making a determination on the unresolved matter,
         and each Executive Officer shall be obligated to consider in good faith
         the analyses and opinions of any such independent experts engaged by
         either of them in making a determination.

12.5     NON-BINDING MEDIATION. Subject to Sections 6.5.2 and 6.5.3(a), if the
         matter has not been resolved by the Executive Officers within thirty
         (30) days of referral in accordance with Section 12.3, or if the
         Executive Officers fail to meet within such thirty (30) days, either
         Party may initiate a non-binding mediation procedure. The non-binding
         mediation shall be administered by the American Arbitration Association
         in accordance with its commercial mediation rules. Unless otherwise
         mutually agreed upon by the Parties, the mediation proceedings shall be
         conducted at the location chosen by the Party not originally requesting
         the resolution of the dispute. The Parties agree that they shall share
         equally the cost of the mediation, including filing and hearing fees,
         and the cost of the mediator(s). Each Party shall have the right, at
         its own expense, to be represented by counsel in such a proceeding. If
         any unresolved matter is not resolved following non-binding mediation
         pursuant to this Section 12.5, either Party may seek any remedy, at law
         or in equity, that may be available.

                                   ARTICLE 13

                    REPRESENTATIONS, WARRANTIES AND COVENANTS

13.1     REPRESENTATION OF AUTHORITY; CONSENTS. Millennium and Aventis each
         represent and warrant to the other Party that as of the Execution Date
         it has full right, power and authority to enter into this Agreement,
         this Agreement has been duly executed by such Party and constitutes a
         legal, valid and binding obligation of such Party, enforceable in
         accordance with its terms, and all necessary consents, approvals and
         authorizations of all government authorities and other persons required
         to be obtained by such Party in connection with the execution,


                                    Page 110
<PAGE>


         delivery and performance of this Agreement have been and shall be
         obtained except with respect to FTC clearance pursuant to the HSR Act.

13.2     NO CONFLICT. Each Party represents to the other Party that
         notwithstanding anything to the contrary in this Agreement, the
         execution and delivery of this Agreement and the performance of such
         Party's obligations hereunder (a) do not conflict with or violate such
         Party's corporate charter and bylaws or any requirement of applicable
         laws of regulations and (b) do not and shall not conflict with, violate
         or breach or constitute a default or require any consent under, any
         contractual obligation of such Party.

13.3     KNOWLEDGE OF PENDING OR THREATENED LITIGATION. Each Party represents
         and warrants to the other Party that there is no claim, investigation,
         suit, action or proceeding pending or, to the knowledge of such Party,
         expressly threatened, against such Party before or by any governmental
         entity or arbitrator that, individually or in the aggregate, could
         reasonably be expected to (i) materially impair the ability of such
         Party to perform any obligation under this Agreement or (ii) prevent or
         materially delay or alter the consummation of any or all of the
         transactions contemplated hereby.

13.4     EMPLOYEE AND CONSULTANT OBLIGATIONS.

         13.4.1   Each Party represents and warrants that all of its employees,
                  officers, and consultants that are supporting the performance
                  of its obligations under this Agreement shall have executed
                  agreements or have existing obligations under law requiring,
                  in the case of employees and officers, assignment to such
                  Party of all inventions made during the course of and as the
                  result of their association with such Party and, in the case
                  of employees, officers and consultants, obligating the
                  individual to maintain as confidential such Party's
                  Confidential Information as well as confidential information
                  of a Third Party which such Party may receive, to the extent
                  required to support such Party's obligations under this
                  Agreement.

         13.4.2   Each Party represents and warrants that it is not in breach of
                  any agreement with any Third Party which would affect its
                  obligations under this Agreement and that it is not in default
                  under any of its existing licenses with any Third Party
                  reasonably necessary for it to fulfill its duties and
                  obligations under this Agreement. Each Party further
                  represents and warrants that it shall use commercially
                  reasonable efforts to maintain such Third Party licenses in
                  effect during the Agreement Term and if it has been accused of
                  a material breach under any such Third Party agreements or
                  licenses, it shall within ten (10) days of such accusation
                  notify the other Party of such accusation.


                                    Page 111
<PAGE>


13.5     BURDENED TECHNOLOGY OBLIGATIONS. Set forth on Exhibit C is a list,
         which is true, complete and correct in all material respects, of each
         agreement between a Third Party and Aventis pursuant to which any
         Burdened Technology Obligations exist as of the Execution Date. Set
         forth on Exhibit D is a list, which is true, complete and correct in
         all material respects, of each agreement between a Third Party and
         Millennium pursuant to which any Burdened Technology Obligations exist
         as of the Execution Date.

13.6     INTELLECTUAL PROPERTY. Each Party represents and warrants to the other
         that as of the Execution Date:

         13.6.1   it is not aware of any claim made against it asserting the
                  invalidity, misuse, unregisterability, unenforceability or
                  non-infringement of any of its intellectual property which is
                  the subject of this Agreement (the "Intellectual Property") or
                  challenging its right to use or ownership of any of the
                  Intellectual Property or making any adverse claim of ownership
                  thereof; and

         13.6.2   it is not aware of any pending or threatened claim or
                  litigation which alleges that its activities to date relating
                  to the Intellectual Property have violated, or by conducting
                  its business as currently proposed to be conducted hereunder
                  would violate, the intellectual property rights of any other
                  person.

13.7     DISCLAIMER OF WARRANTY. Nothing in this Agreement shall be construed as
         a representation made or warranty given by either Party that any
         patents will issue based on pending applications or that any such
         pending applications or patents issued thereon will be valid. EXCEPT AS
         EXPRESSLY SET FORTH IN THIS AGREEMENT, EACH PARTY EXPRESSLY DISCLAIMS,
         WAIVES, RELEASES, AND RENOUNCES ANY WARRANTY, EXPRESS OR IMPLIED,
         INCLUDING, WITHOUT LIMITATION, ANY WARRANTY OF MERCHANTABILITY OR
         FITNESS FOR A PARTICULAR PURPOSE.

                                   ARTICLE 14

                            MISCELLANEOUS PROVISIONS

14.1     INDEMNIFICATION.

         14.1.1   AVENTIS. Aventis agrees to defend Millennium and its
                  Affiliates at Aventis' cost and expense, and will indemnify
                  and hold Millennium and its Affiliates and their respective
                  directors, officers, employees and agents (the "Millennium
                  Indemnified Parties") harmless from and against any losses,
                  costs, damages, fees or expenses arising out of any Third
                  Party claim relating to (i) any breach by Aventis of any of
                  its representations, warranties or obligations pursuant to
                  this Agreement, (ii) the gross negligence or willful
                  misconduct of Aventis, or (iii) injuries resulting from


                                    Page 112
<PAGE>


                  the development, manufacture, use, sale or other disposition
                  of any Joint Development Product outside of North America
                  (provided, however, the foregoing shall not apply with respect
                  to any injuries arising out of NA/Ex-NA Development), or of
                  any Single-Party Target Product, Unilateral Development
                  Product, Ex-Program Product, GT Product, Vaccine Product or
                  any other product or service offered by Aventis, its
                  Affiliates and/or its licensees or collaborators outside of
                  the Research Program or Development and Commercialization
                  activities. In the event of any such claim against the
                  Millennium Indemnified Parties by any Third Party, Millennium
                  shall promptly notify Aventis in writing of the claim and
                  Aventis shall manage and control, at its sole expense, the
                  defense of the claim and its settlement. The Millennium
                  Indemnified Parties shall cooperate with Aventis and may, at
                  their option and expense, be represented in any such action or
                  proceeding. Aventis shall not be liable for any litigation
                  costs or expenses incurred by the Millennium Indemnified
                  Parties without Aventis' prior written authorization. In
                  addition, Aventis shall not be responsible for the
                  indemnification or defense of any Millennium Indemnified Party
                  arising from any negligent or intentional acts by any
                  Millennium Indemnified Party or the breach by Millennium of
                  any obligation or warranty under this Agreement, or any claims
                  compromised or settled without its prior written consent.

         14.1.2   MILLENNIUM. Millennium agrees to defend Aventis and its
                  Affiliates at Millennium's cost, and will indemnify and hold
                  Aventis and its Affiliates and their respective directors,
                  officers, employees and agents (the "Aventis Indemnified
                  Parties") harmless from and against any losses, costs,
                  damages, fees or expenses arising out of any Third Party claim
                  relating to (i) any breach by Millennium of any of its
                  representations, warranties or obligations pursuant to this
                  Agreement or (ii) the gross negligence or willful misconduct
                  of Millennium, or (iii) injuries resulting from the
                  development, manufacture, use, sale or other disposition of
                  any Single-Party Target Product, Unilateral Development
                  Product, Ex-Program Product, Antibody Product, Diagnostic
                  Product or Service or any other product or service offered by
                  Millennium and/or its licensees or collaborators outside of
                  the Research Program or Development and Commercialization
                  activities. In the event of any claim against the Aventis
                  Indemnified Parties by any Third Party, Aventis, shall
                  promptly notify Millennium in writing of the claim and
                  Millennium shall manage and control, at its sole expense, the
                  defense of the claim and its settlement. The Aventis
                  Indemnified Parties shall cooperate with Millennium and may,
                  at their option and expense, be represented in any such action
                  or proceeding. Millennium shall not be liable for any
                  litigation costs or expenses incurred by the Aventis
                  Indemnified Parties without Millennium's prior written
                  authorization. In addition, Millennium shall not be
                  responsible for the indemnification or defense of any Aventis
                  Indemnified Party arising from any negligent or intentional
                  acts by any Aventis Indemnified Party, or the breach by
                  Aventis of any obligation or


                                    Page 113
<PAGE>


                  warranty under this Agreement, or any claims compromised or
                  settled without its prior written consent.

         14.1.3   INSURANCE PROCEEDS. Any indemnification hereunder shall be
                  made net of any insurance proceeds recovered by the
                  Indemnified Party; provided, however, that if, following the
                  payment to the Indemnified Party of any amount under this
                  Article 14, such Indemnified Party recovers any insurance
                  proceeds in respect of the claim for which such
                  indemnification payment was made, the Indemnified Party shall
                  promptly pay an amount equal to the amount of such proceeds
                  (but not exceeding the amount of such indemnification payment)
                  to the Indemnifying Party.

14.2     INSURANCE. Each Party shall use all commercially reasonable efforts to
         maintain insurance, including product liability insurance, with respect
         to its activities hereunder.

         14.2.1   Such insurance shall be in such amounts and subject to such
                  deductibles as the Parties may agree based upon standards
                  prevailing in the industry at the time.

         14.2.2   Either Party may satisfy its obligations under this Section
                  through self-insurance to the same extent.

         14.2.3   At such time as a product is being manufactured by a Party for
                  commercial sale, that Party shall name the other Party as an
                  additional insured on any such policies.

14.3     GOVERNING LAW. This Agreement shall be construed and the respective
         rights of the Parties determined according to the substantive laws of
         the State of Delaware notwithstanding the provisions governing conflict
         of laws under such Delaware law to the contrary, except matters of
         intellectual property law which shall be determined in accordance with
         the intellectual property laws relevant to the intellectual property in
         question.

14.4     ASSIGNMENT. Neither Millennium nor Aventis may assign this Agreement in
         whole or in part without the consent of the other, except (subject to
         Section 14.6) if such assignment occurs in connection with the sale or
         transfer (by merger or otherwise) of all or substantially all of the
         business and assets of Millennium or Aventis to which the subject
         matter of this Agreement pertains, provided that the acquirer confirms
         to the other Party in writing its agreement to be bound by all of the
         terms and conditions of this Agreement. Each Party agrees that,
         notwithstanding any provisions of this Agreement to the contrary, in
         the event that this Agreement is assigned by Millennium in connection
         with the sale or transfer of all or substantially all of the business
         and assets of the Millennium to which the subject matter of this
         Agreement pertains (including in the context of a Change of Control),
         such assignment shall not provide the non-assigning Party with rights
         or access to intellectual property or technology of the acquirer of the


                                    Page 114
<PAGE>

    Confidential Materials omitted and filed with the Securities and Exchange
                    Commission. Asterisks denote omissions.

         Assigning Party. Notwithstanding the foregoing, either Party may assign
         this Agreement to an Affiliate, provided that such Party shall
         guarantee the performance of such Affiliate, and provided further that
         either Party may assign its rights (but not its obligations) pursuant
         to this Agreement in whole or in part to an Affiliate of such Party
         that is controlled by such Party.

14.5     AMENDMENTS. This Agreement and the Exhibits and Schedules referred to
         in this Agreement constitute the entire agreement between the Parties
         with respect to the subject matter hereof, and supersede all previous
         arrangements with respect to the subject matter hereof, whether written
         or oral. The Parties acknowledge that the Exhibits and Schedules
         referred to in this Agreement are being simultaneously delivered by the
         Parties on or before the Execution Date. The Parties also acknowledge
         the simultaneous execution and delivery of the Technology Development
         Agreement, the Technology Transfer Agreement and the Investment
         Agreement, none of which shall be superseded by this Agreement. Any
         amendment or modification to this Agreement shall be made in writing
         signed by both Parties.

14.6     CHANGE OF CONTROL OF MILLENNIUM.

         14.6.1   If a Change of Control occurs during the term of this
                  Agreement, Millennium shall promptly notify Aventis in
                  writing, [**] the Research Program and [**] the Research
                  Program and the Development and Commercialization activities
                  undertaken pursuant to this Agreement (a "Change of Control
                  [**]"). A Change of Control [**] may be made [**] after
                  Aventis' receipt of notice of such Change of Control, such
                  Change of Control [**] to be effective [**] after provision of
                  written notice thereof.

         14.6.2   [**] a Change of Control [**], then the Program Technology and
                  Program Materials of the Research Program shall be [**].

         14.6.3   If Aventis makes a Change of Control [**], the Parties will
                  then [**] all then existing Joint Development Compounds and/or
                  Joint Development Products, [**] after the effectiveness of
                  the Change of Control [**] shall be made [**]. For the
                  purposes of this Agreement, including the payment of royalties
                  under Section 8.3.2, such Joint Development Compounds and/or
                  Joint Development Products will [**] Compounds and/or [**]
                  Products. The provisions of Sections 3.7.1 through and
                  including Section 3.7.5 shall apply with respect to such [**]
                  Compounds and/or [**] Products; PROVIDED THAT, with respect to
                  Section 3.7.2, any costs and expenses associated with the
                  transfer of such UDC or UDC Products shall be the
                  responsibility of [**] such costs to be determined in a manner
                  consistent with the manner in which NA Development Costs and
                  NA/Ex-NA Development Costs are determined. For clarity, the
                  provisions of Section 3.7.6 shall not apply to any such [**]
                  Compounds and/or [**] Products.


                                    Page 115
<PAGE>


14.7     NOTICES. Notices to Millennium shall be addressed to:

                  Millennium Pharmaceuticals, Inc.
                  75 Sidney Street
                  Attention: Chief Executive Officer
                  Cambridge, Massachusetts 02139
                  Facsimile No.: (617) 621-0264

         with a copy to:

                  Attention:    Legal Department

        Notices to Aventis shall be addressed to:

                  Aventis Pharmaceuticals Inc.
                  Route 202-206
                  P.O. Box 6800
                  Bridgewater, New Jersey 08807-0800
                  Attention:   Vice President, Technology Licensing
                               and Alliances

                  Facsimile No.:  (908) 231-3777

        with a copy to:

                  Attention:  Vice President, Legal Corporate
                              Department
                  Facsimile:  (908) 231-4480

         Either Party may change its address to which notices shall be sent by
         giving notice to the other Party in the manner herein provided. Any
         notice required or provided for by the terms of this Agreement shall be
         in writing and shall be (a) sent by registered or certified mail,
         return receipt requested, postage prepaid, (b) sent via a reputable
         overnight courier service, or (c) sent by facsimile transmission, in
         each case properly addressed in accordance with the paragraph above.
         The effective date of notice shall be the actual date of receipt by the
         Party receiving the same.

14.8     FORCE MAJEURE. No failure or omission by either Party in the
         performance of any obligation of this Agreement shall be deemed a
         breach of this Agreement or create any liability if the same shall
         arise from any cause or causes beyond the control of such Party,
         including, but not limited to, the following: acts of gods; acts or
         omissions of any government; any rules, regulations or orders issued by
         any governmental authority or by any officer, department, agency or
         instrumentality thereof; fire; storm; flood; earthquake; accident; war;
         rebellion; insurrection; riot; and invasion; provided that such failure
         or omission resulting from one of the above causes is cured as soon as
         is practicable after the occurrence of one or more of the above
         mentioned causes and in no event more than 270 days after the date of
         occurrence.


                                    Page 116
<PAGE>


14.9     COMPLIANCE WITH EXPORT REGULATIONS. Neither Party shall export any
         technology licensed to it by the other Party under this Agreement
         except in compliance with U.S. export laws and regulations.

14.10    PUBLIC ANNOUNCEMENTS. On the Execution Date, the Parties shall issue
         one or more press releases, the timing and content of which shall be
         mutually agreed. Any announcements or similar publicity with respect to
         the execution of this Agreement shall be agreed upon between the
         Parties in advance of such announcement. The Parties understand that
         this Agreement is likely to be of significant interest to investors,
         analysts and others, and that the Parties therefore may make such
         public announcements with respect thereto, subject to the remainder of
         this Section 14.10. The Parties agree that any such announcement will
         not contain confidential business or technical information and, if
         disclosure of confidential business or technical information is
         required by law or regulation, will make commercially reasonable
         efforts to minimize such disclosure and obtain confidential treatment
         for any such information which is disclosed to a governmental agency or
         group. Each Party agrees to provide to the other Party a copy of any
         public announcement as soon as reasonably practicable under the
         circumstances prior to its scheduled release. Except under
         extraordinary circumstances, each Party shall provide the other with an
         advance copy of any press release at least five (5) business days prior
         to the scheduled disclosure. Each Party shall have the right to
         expeditiously review and recommend changes to any announcement
         regarding this Agreement or the subject matter of this Agreement.
         Except as otherwise required by law, the Party whose press release has
         been reviewed shall remove any information the reviewing Party
         reasonably deems to be inappropriate for disclosure. The contents of
         any such announcement or similar publicity which has been reviewed and
         approved by the reviewing Party can be re-released by either Party
         without a requirement for re-approval. Furthermore, each Party shall
         give the other Party a reasonable opportunity to review all filings
         with the United States Securities and Exchange Commission describing
         the terms of this Agreement prior to submission of such filings, and
         shall give due consideration to any reasonable comments by the
         non-filing Party relating to such filing, including without limitation
         the provisions of this Agreement for which confidential treatment
         should be sought.

14.11    NON-SOLICITATION. During the Research Program Term, and for a period of
         one (1) year thereafter, neither Party shall either directly or
         indirectly solicit, recruit, induce, encourage or attempt to induce or
         encourage any employee of the other Party or any independent contractor
         primarily dedicated to the Research Program, or in Development or
         Commercialization activities to terminate his or her employment with
         such other Party and become employed by or consult for such other Party
         whether or not such employee is a full-time employee of such other
         Party, whether or not such employment is pursuant to a written
         agreement or is at-will.


                                    Page 117
<PAGE>


14.12    INDEPENDENT CONTRACTORS. It is understood and agreed that the
         relationship between the Parties is that of independent contractors and
         that nothing in this Agreement shall be construed as authorization for
         either Millennium or Aventis to act as agent for the other. Members of
         the Joint Steering Committee, the Joint Research Committee, the Joint
         Development Committee, the Joint Commercialization Committee and any
         subcommittees thereof shall be, and shall remain, employees of
         Millennium or Aventis, as the case may be. No Party shall incur any
         liability for any act or failure to act by members of the Joint
         Steering Committee, the Joint Research Committee, the Joint Development
         Committee, the Joint Commercialization Committee and any subcommittees
         thereof who are employees of such other Party.

14.13    NO STRICT CONSTRUCTION. This Agreement has been prepared jointly and
         shall not be strictly construed against either Party.

14.14    HEADINGS. The captions or headings of the sections or other
         subdivisions hereof are inserted only as a matter of convenience or for
         reference and shall have no effect on the meaning of the provisions
         hereof.

14.15    NO IMPLIED WAIVERS; RIGHTS CUMULATIVE. No failure on the part of
         Millennium or Aventis to exercise, and no delay in exercising, any
         right, power, remedy or privilege under this Agreement, or provided by
         statute or at law or in equity or otherwise, shall impair, prejudice or
         constitute a waiver of any such right, power, remedy or privilege or be
         construed as a waiver of any breach of this Agreement or as an
         acquiescence therein, nor shall any single or partial exercise of any
         such right, power, remedy or privilege preclude any other or further
         exercise thereof or the exercise of any other right, power, remedy or
         privilege.

14.16    SEVERABILITY. If any provision hereof should be held invalid, illegal
         or unenforceable in any respect in any jurisdiction, the Parties hereto
         shall substitute, by mutual consent, valid provisions for such invalid,
         illegal or unenforceable provisions which valid provisions in their
         economic effect are sufficiently similar to the invalid, illegal or
         unenforceable provisions that it can be reasonably assumed that the
         Parties would have entered into this Agreement with such valid
         provisions. In case such valid provisions cannot be agreed upon, the
         invalid, illegal or unenforceable of one or several provisions of this
         Agreement shall not affect the validity of this Agreement as a whole,
         unless the invalid, illegal or unenforceable provisions are of such
         essential importance to this Agreement that it is to be reasonably
         assumed that the Parties would not have entered into this Agreement
         without the invalid, illegal or unenforceable provisions.

14.17    EXECUTION IN COUNTERPARTS. This Agreement may be executed in
         counterparts, each of which counterparts, when so executed and
         delivered, shall be deemed to be an original, and all of which
         counterparts, taken together, shall constitute one and the same
         instrument.


                                    Page 118
<PAGE>


14.18    NO THIRD PARTY BENEFICIARIES. No person or entity other than Aventis,
         Millennium and their respective Affiliates and permitted assignees
         hereunder shall be deemed an intended beneficiary hereunder or have any
         right to enforce any obligation of this Agreement.

14.19    NO CONSEQUENTIAL DAMAGES. UNLESS RESULTING FROM A PARTY'S GROSS
         NEGLIGENCE OR WILLFUL MISCONDUCT, NEITHER PARTY HERETO WILL BE LIABLE
         FOR SPECIAL, INCIDENTAL OR CONSEQUENTIAL DAMAGES ARISING OUT OF THIS
         AGREEMENT OR THE EXERCISE OF ITS RIGHTS HEREUNDER, INCLUDING WITHOUT
         LIMITATION LOST PROFITS ARISING FROM OR RELATING TO ANY BREACH OF THIS
         AGREEMENT, REGARDLESS OF ANY NOTICE OF SUCH DAMAGES. NOTHING IN THIS
         SECTION 14.19 IS INTENDED TO LIMIT OR RESTRICT THE INDEMNIFICATION
         RIGHTS OR OBLIGATIONS OF EITHER PARTY.

                                   ARTICLE 15

                                   HSR FILING

15.1     HSR FILING. To the extent necessary, each of Millennium and Aventis
         shall, within fifteen (15) days after the Execution Date, file with the
         Federal Trade Commission and the Antitrust Division of the U.S.
         Department of Justice, any notification and report form required of it
         in the reasonable opinion of both Parties under the HSR Act with
         respect to the transactions contemplated hereby. The parties shall
         cooperate with one another to the extent necessary in the preparation
         of any notification and report form required to be filed under the HSR
         Act. Each Party shall be responsible for its own costs, expenses, and
         filing fees associated with any filing under the HSR Act.

15.2     HSR-RELATED DEFINITIONS. As used in Section 15.1, the following terms
         have the following meanings:

         15.2.1   "DOJ" means the United States Department of Justice.

         15.2.2   "FTC" means the United States Federal Trade Commission.

         15.2.3   "HSR Act" means the Hart-Scott-Rodino Antitrust Improvements
                  Act of 1976, as amended (15 U.S.C. Sec. 18a), and the rules
                  and regulations promulgated thereunder.

         15.2.4   "HSR Clearance Date" means the earlier of (i) the date on
                  which the FTC shall notify Millennium and Aventis of early
                  termination of the applicable waiting period under the HSR Act
                  or (ii) the day after the date on which the applicable waiting
                  period under the HSR Act expires, but in no event earlier than
                  July 6, 2000.


                                    Page 119
<PAGE>


         15.2.5   "HSR Filing" means filings by Aventis and Millennium with the
                  FTC and the Antitrust Division of the DOJ of a Notification
                  and Report Form for Certain Mergers and Acquisitions (as that
                  term is defined in the HSR Act) with respect to the matters
                  set forth in this Agreement, together with all required
                  documentary attachments thereto.

    IN WITNESS WHEREOF, the Parties have executed this Agreement as of the
date first set forth above.

                                   MILLENNIUM PHARMACEUTICALS, INC.

                                   By: /s/ Steven H. Holtzman
                                       ------------------------------------
                                   Title: Chief Business Officer
                                          ---------------------------------

                                   AVENTIS PHARMACEUTICALS INC.

                                   By: /s/ Frank Douglas, M.D.
                                      -------------------------------------
                                   Title: Executive Vice President
                                          ---------------------------------


                                    Page 120
<PAGE>


                                  SCHEDULE 4.2.

         CRITERIA FOR THE ASSIGNMENT OF RESPONSIBLE MANUFACTURING PARTY

When considering which partner will be the responsible manufacturing Party for a
given Joint Development Compound or Joint Development Product, the following
guidelines should be reviewed at a minimum at the time of the sourcing decision:

1.       Systems must be in place OR described clearly in detail, including
         resource allocation, management structure and responsibilities, and
         time-line for implementation, for the qualification of suppliers of raw
         materials, packaging components, and pharmaceutical excipients.

2.       A Sales and Operations Planning system must be in place OR be clearly
         outlined in detail, including how the system functions, responsible
         functions participating in the process, and a time-line when the
         process will be fully functional.

3.       Inventory Management Systems must be in place, OR be clearly outlined
         in detail, including how the system functions, responsible functions
         participating in the process, and a time-line when the process will be
         fully functional, including but not limited to:

         -        ability to trace product throughout the distribution network

         -        ability to rapidly recall product through the distribution
                  network

         -        management of pharmaceutical technical complaints, at least in
                  as much as the manufacturer contributes to the investigation
                  of the complaint.

4.       A system for management of third party contractors (in as much as they
         participate in the manufacturing, testing, validation, storage,
         distribution, and supply chain management of the Compound or product),
         must be in place or clearly outlined in detail, including system
         description, resource allocation, and implementation time-line.

5.       An EHS management system that is supported by qualified personnel must
         be in place, OR clearly outlined in detail including timelines for
         implementation,. To assure protection of employee health and safety,
         protection of the environment and regulatory compliance, the EHS
         program shall address safety, industrial hygiene, process safety,
         environmental protection, occupational medicine and product
         stewardship.

6.       Systems for insuring compliance to world-wide cGMPs, including but not
         limited to:

         -        qualification and training of staff

         -        qualification and validation of facilities and equipment for
                  manufacturing, storage, and testing of Compound and Product


                                    Page 1
<PAGE>

         -        qualification and validation of processes, manual or
                  computerized, pertaining to manufacturing, testing, cleaning,
                  storing, distributing, and inventory tracking of Compound and
                  Product

         -        Change Control, Batch Record Review, Batch Releasing, and
                  Failure Investigation

         -        must be in place OR clearly outlined in detail, including
                  process descriptions, resource allocation, management
                  structure, and implementation time-lines.

7.       The Manufacturing Party must accept and be able to meet world-wide
         demand for the Compound or Product, unless mutually agreed by both
         parties in writing at the time of the sourcing decision.

8.       The Manufacturing Party must bear all capital costs associated with
         manufacturing the Compound or Product


                                    Page 2