Document:

<PAGE>
                                                                   Exhibit 10.22

                         FOCUSED COLLABORATION AGREEMENT

                                     between

                          THE PROCTER & GAMBLE COMPANY

                                       and

                         REGENERON PHARMACEUTICALS, INC.

EXECUTION COPY
<PAGE>
                         FOCUSED COLLABORATION AGREEMENT

<TABLE>
<S>                                                                                       <C>
I.     Definitions........................................................................
II.    Termination of the Multi-Project Collaboration Agreement; Overview;
       and Management Committee...........................................................
III.   Research and Development...........................................................
IV.    Marketing of Products..............................................................
V.     License Grants.....................................................................
VI.    Royalties and Accounting...........................................................
VII.   Patents and Infringement...........................................................
VIII.  Confidentiality....................................................................
IX.    Representations, Warranties and Indemnification....................................
X.     Term, Termination, Change of Control...............................................
XI.    Miscellaneous......................................................................
XII.   Execution..........................................................................
</TABLE>
<PAGE>
                         FOCUSED COLLABORATION AGREEMENT

Made as of the 31st day of December, 2000, by and among:

         The Procter & Gamble Company, an Ohio corporation having its principal
offices at One Procter & Gamble Plaza, Cincinnati, Ohio 45202 (hereinafter,
together with its Affiliate Procter & Gamble Pharmaceuticals, Inc., "Procter &
Gamble" or "P&G"), and

         Regeneron Pharmaceuticals, Inc., a New York corporation having its
principal office at 777 Old Saw Mill River Road, Tarrytown, New York 10591-6707
(hereinafter, together with its Affiliates, "Regeneron").

The following sets forth the background for this Agreement:

         Procter & Gamble conducts research and develops and markets
         pharmaceutical products for the treatment of a variety of disorders,
         including without limitation products having utility in the treatment
         of bone disorders, skeletal muscle disorders, cardiac muscle disorders,
         arthritis, gastrointestinal disorders, obesity, and antiinfectives.

         Regeneron conducts research for the development and commercialization
         of pharmaceutical products, based on significant expertise in
         identifying and developing molecular receptor targets and compounds
         that mediate a variety of disorders. Regeneron has entered into
         collaborative agreements with third parties for the research,
         development and commercialization of products regarding several such
         targets identified by Regeneron. Regeneron is independently pursuing
         research on other such targets.

         Regeneron and Procter & Gamble entered into an agreement on the 11th
         day of December 1996, establishing a collaborative effort to perform
         research and develop and market products for the prevention, diagnosis,
         and treatment of skeletal muscle disorders. Regeneron and Procter &
         Gamble entered into a subsequent agreement on the 13th day of May, 1997
         broadening the scope of their collaboration (as the same has been
         amended from time to time, the "Multi-Project Collaboration
         Agreement").

                                       2
<PAGE>
         Pursuant to the terms of this Agreement, Procter & Gamble and Regeneron
         wish to terminate the Multi-Project Collaboration Agreement and enter
         into this Agreement to pursue research, development and marketing of
         products based on specific focused areas.

         Procter & Gamble and Regeneron intend fully to utilize their
         capabilities, capitalize on each other's expertise, and put forth
         Commercially Reasonable Efforts to achieve this objective, and
         recognize that each party is contributing valuable technologies and
         capabilities to this effort and that the combination of these
         compatible and complementary technologies and capabilities creates the
         basis for a successful collaboration.

Accordingly, the Parties agree to the following terms and conditions:

                                       3
<PAGE>
                             ARTICLE I - DEFINITIONS

         1.1. "Affiliate" means any entity that directly or indirectly Owns, is
Owned by, or is under common Ownership with a Party to this Agreement. In no
event will Amgen-Regeneron Partners, any legal entity that Regeneron forms with
Glaxo that relates to their July 1993 agreement, any legal entity that Regeneron
forms with Pharmacopeia, Inc. that relates to their October 1996 agreement, or
any legal entity that Regeneron forms with Procter & Gamble that relates to this
Agreement be deemed to be an Affiliate of Regeneron under this Agreement. "Owns"
or "Ownership" means direct or indirect possession of more than fifty percent
(50%) of the votes of holders of a corporation's voting securities or a
comparable equity interest in any other type of entity.

         1.2. "Agreement" means the present agreement together with all
attachments.

         1.3. "Agrin" means the compounds claimed in the United States Patent
Application Serial Number [********] and any continuations, divisionals or
continuation-in-parts thereof, and any molecules representing one or more amino
acid substitutions, deletions, or additions derived therefrom.

         1.4. "Allowable Product Expense" means Direct Costs incurred by either
Party pursuant to an approved Product Plan. Allowable Product Expenses will be
recognized in accordance with GAAP.

         1.5. "Article" means any article of this Agreement.

         1.6. "Commercially Reasonable Efforts" means efforts and resources
commonly used in the research-based pharmaceutical industry for a compound or
product at a similar stage of research, development or commercialization, and
having similar market potential. Commercially Reasonable Efforts shall be
determined taking into account the stage of research, development or
commercialization of the compound or product, the cost-effectiveness of efforts
or resources while optimizing profitability, the competitiveness of alternative
products that are or expected to be in the relevant marketplace, the proprietary
position of the product, the regulatory and business environment, the likelihood
of regulatory approval and product reimbursement, the profitability of the
product, the existence of alternative products that may also be developed by the
Parties, and all other relevant factors. Commercially Reasonable Efforts shall
be determined on a compound-by-compound and market-by-market basis, and it is
anticipated that the level of effort will

                                       4
<PAGE>
change over time reflecting changes in the status of the compound, product and
the market involved.

         1.7. "Competing Product" means any compound, product, method or system
that is indicated for the same disease state and has the same mechanism of
action as a Development Compound or Marketed Compound that is actively being
developed or marketed. Competing Product shall not include Excluded Technology.

         1.8. "Compound" means a chemical entity, which is not Excluded
Technology, with research or commercial utility in the Field for methods of
research, diagnosis, treatment or prevention of any disease or disorder in
humans or animals, and which

              (a) is conceived and/or reduced to practice by Regeneron, or
       acquired by Regeneron from a Third Party with the right to sublicense,
       before or during the Research Term; or

              (b) is conceived and/or reduced to practice by Procter & Gamble,
       or acquired by Procter & Gamble from a Third Party with the right to
       sublicense, prior to or during the Research Term.

         Compound includes Research Compounds, Development Compounds and
Marketed Compounds that may be useful in the Field for methods of research,
diagnosis, treatment or prevention of any disease or disorder in humans or
animals. Each Compound shall also be deemed to include all indications,
formulations, line extensions, or modes of administration thereof.

         1.9 "Development Committee" or "DC" means the committee established
pursuant to Section 2.5(c).

         1.10 "Development Compound" means a Compound that has been demonstrated
to meet Success Criteria as ready to begin regulated safety studies and
development of clinical supplies whether or not it has been designated by the
Operations Committee for further development pursuant to Section 3.3. The terms
Development Compound and Lead Compound may be used interchangeably.

         1.11. "Direct Costs" means costs, of a nature, amount, and method of
calculation approved by the Operations Committee via the Research Collaboration
Plan and/or Product Plan, that are incurred by either Party, based upon efforts,
funds and/or resources expended to perform its obligations under such plan.
Direct Costs may include costs associated with activities performed by a Party,
or by a Third Party under an appropriate

                                       5
<PAGE>
agreement pursuant to Section 2.9, for the research, development or marketing of
Compounds. Direct Costs shall not include any mark-up or profit above actual
costs.

         1.12 "DDR Field" means the discovery, development, supply and
commercialization of products or processes that modulate the function of the
receptor tyrosine kinases DDR1 and/or DDR2 (or any receptor having at least
seventy-five percent (75%) homology with DDR1 or DDR2) whose biological action
is primarily due to this modulation.

         1.13. "Effective Date" means the date described in Section 10.1(a).

         1.14. "Excluded Technology" means any invention, trade secret or other
information, whether tangible or intangible, whether or not patentable, that is:

              (a) conceived or reduced to practice by Regeneron, or acquired
       from a Third Party, or Procter & Gamble, by Regeneron before or during
       the Term insofar as such invention, trade secret or other information is
       not in the Field, including, without limitation, the subject matter
       listed in Attachment 1.14(a), (collectively, the "Regeneron Excluded
       Technology"). Without limiting the foregoing, Regeneron Excluded
       Technology shall include any compound, product, method, system, Know-how
       or Patent licensed by Regeneron to Procter & Gamble pursuant to the
       Multi-Project Collaboration Agreement and not within the Field, any
       Procter & Gamble Retained Project, or any Mutual Retained Project; or

              (b) conceived or reduced to practice by Procter & Gamble, or
       acquired by Procter & Gamble from a Third Party, or Regeneron, before or
       during the Term insofar as such invention, trade secret and other
       information (i) is not in the Field, (ii) are small molecule Research
       Compounds that have not met Success Criteria, or (iii) is part of
       [**************************] ("Procter & Gamble Excluded Technology").
       Without limiting the foregoing, Procter & Gamble Excluded Technology
       shall include any compound, product, method, system, Know-how or Patent
       licensed by Procter & Gamble to Regeneron pursuant to the Multi-Project
       Collaboration Agreement and not within the Field, any Regeneron Retained
       Project, or any Mutual Retained Project. Notwithstanding the foregoing,
       Procter & Gamble Excluded Technology shall not include any compound,
       product, method or system which is in human clinical development or
       Marketed and is acquired by Procter & Gamble from a Third Party which, at
       the time of acquisition is indicated for the same disease state and is
       known to have the same mechanism of action as a Development Compound or
       Marketed Compound; or

                                       6
<PAGE>
              (c) conceived or reduced to practice under the Multi-Project
       Collaboration Agreement prior to December 31, 2000 in connection with a
       Retained Project, and is not in the Field; or

              (d) conceived or reduced to practice by a Party after December 31,
       2000 in connection with a Retained Project and is not in the Field.

         1.15 "Field" means the collective areas in which the Parties shall
collaborate encompassing the discovery, development, supply and
commercialization of products or processes in the Muscle Field, the GPCR Field
or the DDR Field.

         1.16. "Fiscal Quarter" means each period of three (3) months ending on
31 March or 30 June or 30 September or 31 December.

         1.17. "Fiscal Year" means the twelve (12) month period of time from
July 1 to June 30, except that the first Fiscal Year commences on the Effective
Date and ends on June 30, 2001 and the last Fiscal Year during the Research Term
shall end on the last day of the Research Term.

         1.18. "FTE" or "Full Time Equivalent" means one Effort Year of an
employee or class of employees. "Effort Year" means
[***************************] hours of direct effort expended on approved
activities during a Fiscal Year.

         1.19. "GAAP" means generally accepted accounting principles.

         1.20. "GPCR" means a G-protein coupled receptor.

         1.21 "GPCR Field" means the discovery, development, supply and
commercialization of products or processes that directly bind and/or modulate
the function of the twelve GPCRs as set forth in Attachment 1.21, as the same
may be modified pursuant to Section 2.4(e).

         1.22 "Health Registration" means any and all consents, licenses,
authorizations, reimbursement pricing or approvals required by the U.S. Food and
Drug Administration or any Ministry of Health for the distribution, sale,
manufacture, or testing of a pharmaceutical product, including, without
limitation, an IND, NDA or supplemental NDA or other application or supplemental
application for a Health Registration.

                                       7
<PAGE>
         1.23. "IND" means an Investigational New Drug application, as described
by the U.S. Food, Drug and Cosmetics Act of 1938, 21 U.S.C. 301 et seq., as
amended, and associated regulations.

         1.24. "Inventions" or "Technology" mean all inventions, trade secrets
and other information, whether tangible or intangible, whether or not
patentable, resulting from work by the parties (either individually or jointly)
in the Field during the Research Term.

         1.25 "Joint Projects" mean the research projects undertaken by the
parties pursuant to the Multi-Project Collaboration Agreement and identified in
Attachment 2.2 as "Joint Projects".

         1.26. "J-V" means such collaborative relationship as may be established
pursuant to Section 3.7 of this Agreement. J-V may or may not be structured as a
separate legal entity, such as a corporation, partnership, LLC, or such other
form as the Parties may agree. In agreeing on the form of the collaborative
relationship, the Parties shall take appropriate account of, among other
factors, ease of administration and tax liabilities.

         1.27. "Know-how" means the entire right, title and interest in trade
secret technology. "P&G Know-how" shall mean the entire right, title and
interest in Know-how owned solely or jointly by Procter & Gamble with a Third
Party. "Regeneron Know-how" shall mean the entire right, title and interest in
Know-how owned solely or jointly by Regeneron with a Third Party. "Joint
Know-how" shall mean the entire right, title and interest in Know-how jointly
owned by the Parties pursuant to Section 5.1(b).

         1.28. "Lead Compound" means a Research Compound that has been
demonstrated to meet Success Criteria as ready to begin regulated safety studies
and development of clinical supplies pursuant to Section 3.3 during the Research
Term or Tail Period. The terms Development Compound and Lead Compound may be
used interchangeably.

         1.29. "Major Country" means the United States, United Kingdom, Belgium,
Germany, France, Italy, Netherlands and Canada.

         1.30. "Major Decision" means the following decisions to be made by the
Operations Committee:

                                       8
<PAGE>
              (a) Approval of all long-range strategic plans developed pursuant
       to this Agreement, including without limitation the Research
       Collaboration Plan and Product Plans;

              (b) Disposition of any interest in any type of intellectual
       property in which the Parties have rights under this Agreement (other
       than routine copyright transfers incident to publications made pursuant
       to Section 8.3), including without limitation any license, assignment, or
       registration of any Patent, trademark or Know-how;

              (c) Determination of whether a Research Compound has met the
       Success Criteria for further development;

              (d) Expenditure of any funds, or incurrence of any obligation, in
       excess of [*****************************************] for the acquisition
       of a particular piece of property (including without limitation real or
       intellectual property), equipment or service regarding work under this
       Agreement, unless such expenditure or obligation is explicitly authorized
       in a Research Project Plan or a Product approved by the Operations
       Committee;

              (e) Expenditure of any funds, or incurrence of any obligation,
       regarding any budget item that cannot be resolved by the Program
       Committee or by the Development Committee;

              (f) Initiation or settlement of any lawsuits by or against the
       Parties (except against each other) in connection with this Agreement,
       subject to Section 9.3;

              (g) Acceptance of contracts outside the ordinary course of
       business of the collaboration as described in Section 2.7 and any
       contracts with either Party or its Affiliates or any contracts pertaining
       to the collaboration in which a Party has a beneficial interest;

              (h) Selection of any trademark regarding a Development Compound or
       Marketed Compound; and

              (i) Initiation of any recalls of Marketed Compounds.

         1.31. "Marketed Compound" means a Compound which is sold pursuant to
this Agreement in any country in the Territory.

         1.32. "Muscle Field" means the discovery, development, supply and/or
commercialization of products (except MuSK and/or Agrin) or processes that
diagnose, prevent and/or treat conditions in humans and animals associated with
the promotion or

                                       9
<PAGE>
protection of skeletal muscle mass or function (including, without limitation,
the diagnosis, treatment or prevention of muscle atrophy or sarcopenia).

         1.33. "Mutual Retained Projects" means the research projects undertaken
by the parties pursuant to the Multi-Project Collaboration Agreement and
identified in Attachment 2.2 as "Mutual Retained Projects."

         1.34 "MuSK" means the materials disclosed in [**********] of the United
States Patent Application Serial Number [*********] and any molecules
representing one or more amino acid substitutions, deletions, or additions
derived therefrom which exhibit a biological activity substantially identical to
the materials disclosed in [*************] of the United States Patent
Application Serial Number [**********]

         1.35 "NDA" means a New Drug Application or Biologics License
Application as described by the U.S. Food, Drug and Cosmetics Act of 1938, 21
U.S.C. 301 et seq., as amended, and associated regulations, or the U.S. Public
Health Service Act, 42 U.S.C. 201 et seq., as amended and associated
regulations.

         1.36. "Net Sales" means total gross realization less:
[*******************************************************************************
*****************************************************************]

         1.37. "Operations Committee" or "OC" means the committee described in
Section 2.5(a).

         1.38. "Opting Out Party" means the Party that Opts Out of those
development and/or marketing activities with respect to a Compound as specified
in Sections 3.4(b), 3.6, and 10.3(a). "Opts Out" means that the Opting Out Party
either decides not to continue with such activities or does not fund its share
of Allowable Product Expenses with respect to such activities.

         1.39. "Party" means Regeneron or Procter & Gamble.

         1.40. "Patent" means the entire right, title and interest in a Valid
Claim in a patent application, and all continuing and divisional patent
applications, continuations-in-part, reissue applications and all other related
patent applications claiming priority, indirectly and directly, to such
application, and all patents issuing therefrom, worldwide.

                                       10
<PAGE>
"P&G Patent Rights" shall mean the entire right, title and interest in a Patent
owned solely by Procter & Gamble or jointly by Procter & Gamble with a Third
Party. "Regeneron Patent Rights" shall mean the entire right, title and interest
in a Patent owned solely by Regeneron or jointly by Regeneron with a Third
Party. "Joint Patent Rights" shall mean the entire right, title and interest in
a Patent jointly owned by Regeneron and Procter & Gamble.

         1.41. "Proceeding Party" means the Party that is not an Opting Out
Party with respect to the development or marketing of a Compound either in the
entire Territory or in one or more specific countries therein.

         1.42. "Procter & Gamble Inventions" shall mean the entire right, title
and interest in Inventions owned solely or jointly by Procter & Gamble with a
Third Party. "Regeneron Inventions" shall mean the entire right, title and
interest in Inventions owned solely or jointly by Regeneron with a Third Party.
"Joint Inventions" shall mean the entire right, title and interest in Inventions
jointly owned by the Parties.

         1.43 "Procter & Gamble Retained Projects" means the research projects
undertaken by the Parties pursuant to the Multi-Project Collaboration Agreement
and identified in Attachment 2.2(c) as "Procter & Gamble Retained Projects".

         1.44. "Procter & Gamble Technology" means any invention, Know-how or
other information, whether tangible or intangible, whether or not patentable, in
the Field, and which:

              (a) is not Procter & Gamble Excluded Technology, and

              (b) is conceived or reduced to practice by Procter & Gamble or
       acquired or licensed by Procter & Gamble from a Third Party with the
       right to sublicense,

                     (i) before or during the Research Term; or

                     (ii) after the Research Term, but during the term of a J-V,
                     regarding a Development Compound or Marketed Compound.

         Procter & Gamble Technology may include, without limitation, research
methods and materials (including without limitation genetic materials,
receptors, cell lines and transgenic animals) useful in performing research,
Lead Compounds, formulations, chemical synthesis and manufacturing processes,
methods of diagnosis and methods of treatment.

                                       11
<PAGE>
         1.45. "Product Plan" means the annual compilation of objectives,
activities, resource allocations, Success Criteria, Allowable Product Expenses
and budgets regarding the development and/or marketing of Development Compounds
and/or Marketed Compounds agreed to by the OC, as more thoroughly described in
Section 3.3(b).

         1.46. "Program Committee" or "PC" means the committee established
pursuant to Section 2.5(b).

         1.47. "Regeneron Retained Projects" means all research projects
undertaken by the Parties pursuant to the Multi-Project Collaboration Agreement
other than the Procter & Gamble Retained Projects, the Mutual Retained Projects,
and the Joint Projects, including, by way of example, but not limitation, the
specific projects identified in Attachment 2.2(c) as "Regeneron Retained
Projects".

         1.48. "Regeneron Technology" means any invention, Know-how or other
information, whether tangible or intangible, whether or not patentable in the
Field, and which:

              (a) is not Regeneron Excluded Technology, and

              (b) is conceived or reduced to practice by Regeneron or acquired
       or licensed by Regeneron from a Third Party with the right to sublicense,

                     (i) before or during the Research Term; or

                     (ii) after the Research Term, but during the term of a J-V,
                     regarding a Development Compound or Marketed Compound.

         Regeneron Technology may include, without limitation, research methods
and materials (including without limitation genetic materials, receptors, cell
lines and transgenic animals) useful in performing research, Targets, Compounds,
formulations, chemical synthesis and manufacturing processes, methods of
diagnosis and methods of treatment.

         1.49. "Research Collaboration Plan" means, on a Fiscal Year basis, the
compilation of objectives, prioritization of Research Projects and work on new
areas of research, Success Criteria and overall budget for work by the Parties
during the Research Term, but not including development and/or marketing
activities.

         1.50. "Research Compound" means a Compound that has not yet met the
Success Criteria.

                                       12
<PAGE>
         1.51. "Research Project" shall mean research conducted by the Parties
for the purpose of identifying, optimizing, and testing a specific Target,
Validated Target and/or Research Compound.

         1.52. "Research Project Plan" shall mean, on a Fiscal Year basis, the
compilation of activities, milestones, budget, and Success Criteria relating to
a Research Project.

         1.53. "Research Term" means the period of time beginning on the
Effective Date and unless terminated earlier pursuant to 10.3, ending December
31, 2005.

         1.54. "Retained Projects" means the Mutual Retained Projects, Procter &
Gamble Retained Projects, and Regeneron Retained Projects.

         1.55. "Royalty Term" means the period from the first Net Sales in the
first country to the final payment of royalties in the last country pursuant to
Section 6.1.

         1.56. "Section" means any section of this Agreement.

         1.57. "Securities Agreements" mean the following agreements between the
parties: the Registration Rights Agreement, the Securities Purchase Agreement
and the Warrant Agreement, all dated May 13, 1997, as each may be amended,
supplemented or modified from time to time and the Stock Purchase Agreement and
Registration Rights Agreement both dated December 11, 1996, as each may be
amended, supplemented or modified from time to time.

         1.58. "Success Criteria" means the specific criteria set forth in a
Research Project Plan and Research Collaboration Plan and approved by the OC
that define the minimum technical and commercial requirements for a Research
Compound to be designated a Development or Lead Compound.

         1.59. "Sumitomo Compound" means any Compound which:

              (a) is claimed by a Regeneron Patent;

              (b) is owned by Regeneron prior to the Effective Date, or
       conceived and solely reduced to practice solely by Regeneron during the
       Research Term; and

              (c) Sumitomo Chemical Company Limited or its affiliates exercise
       rights pursuant to its Technology Development Agreement with Regeneron
       executed in March 1989 (hereinafter the "Sumitomo Agreement).

                                       13
<PAGE>
         1.60. "Tail Period" means the [************] immediately after the end
of the Research Term.

         1.61. "Target" means any gene, receptor, ligand, or other compound
which has actual or potential utility in the Field for the identification,
research or commercialization of Compounds for the prevention, diagnosis, or
treatment of diseases or other disorders in humans or animals.

         1.62. "Term" means the period of time specified in Section 10.1(b).

         1.63. "Territory" means the entire world, excluding Japan with respect
to any Sumitomo Compound. Japan shall be included in the Territory except for
Sumitomo Compounds.

         1.64. "Third Party" means any entity other than Regeneron or Procter &
Gamble or their Affiliates or a J-V established in accordance with this
Agreement.

         1.65. "Valid Claim" shall mean any claim in a published and unexpired
application or patent included within a Patent which claim has not been held
unenforceable, unpatentable or invalid by a decision of a court or other
governmental agency of competent jurisdiction, unappealable or unappealed within
the time allowed for appeal, and which has not been finally abandoned or
admitted to be invalid or unenforceable through disclaimer.

         1.66. "Validated Target" means a Target which has been shown to meet
all of the following criteria approved by the PC: (a) the Target is well
characterized (i.e., its biochemical and physiological actions are reasonably
well understood); (b) agents, ligands, or intracellular molecules that interact
with the Target demonstrate a desired effect on a biological process in
relationship to a disease state or disorder; and (c) the Target is shown to be
present in human tissue with the disease state or condition.

    ARTICLE II - TERMINATION OF THE MULTI-PROJECT COLLABORATION AGREEMENT AND
 OVERVIEW AND MANAGEMENT OF COLLABORATION

                                       14
<PAGE>
         2.1 TERMINATION OF THE MULTI-PROJECT COLLABORATION AGREEMENT. Subject
to the terms of Section 2.3, the Multi-Project Collaboration Agreement is hereby
terminated on the Effective Date and superseded by the terms of this Agreement.
Notwithstanding anything to the contrary in the Multi-Project Collaboration
Agreement, no license granted in Article V of the Multi-Project Collaboration
Agreement shall extend beyond the Effective Date.

         2.2 RIGHTS TO REGENERON RETAINED PROJECT, PROCTER & GAMBLE RETAINED
PROJECT, AND MUTUAL RETAINED PROJECT UPON TERMINATION OF THE MULTI-PROJECT
COLLABORATION AGREEMENT. Patents and Know-how regarding all inventions, trade
secrets and other information, whether tangible or intangible, whether or not
patentable, resulting from work by the Parties during the Research Term of the
Multi-Project Collaboration Agreement were owned: (i) by P&G, if such technology
was conceived and reduced to practice solely by employees of P&G; and (ii)
jointly, if such technology was conceived and/or reduced to practice either
solely by employees of Regeneron or jointly by employees of Procter & Gamble and
Regeneron. Contrary to the Multi-Project Collaboration Agreement, Regeneron
shall own all Inventions discovered by employees of Regeneron as part of any
Regeneron Retained Project and having no utility in the Field as of the
Effective Date. The Parties shall grant the following licenses to the Retained
Projects identified in Attachment 2.2(c) upon the Effective Date of this
Agreement:

         (a) Subject to the terms of subsection (g) below, Procter & Gamble
hereby grants Regeneron an Exclusive License under its Patents and Know-how
whether solely owned by Procter & Gamble or jointly owned with Regeneron which
were conceived and reduced to practice in connection with any Regeneron Retained
Project at any time through December 31, 2000 and as of December 31, 2000 have
no known use in the Field or in any Procter & Gamble Retained Project to make,
have made, use, import, offer for sale and sell any products for the prevention,
diagnosis, or treatment of any diseases or disorders in humans or animals in
connection with any Regeneron Retained Project. Procter & Gamble hereby grants
Regeneron a Non-Exclusive License under its Patents and Know-how which were
conceived and reduced to practice in connection with any Regeneron Retained
Project at any time through December 31, 2000 and as of December 31, 2000 have
known use in the Field or in any Procter & Gamble Retained Project, to make,
have made, use, import, offer for sale and sell any products for the prevention,
diagnosis, or treatment of any disease or disorder in humans or animals in
connection with any Regeneron Retained Project.

                                       15
<PAGE>
         (b) Regeneron hereby grants to Procter & Gamble an Exclusive License
under its Patents and Know-how whether solely owned by Regeneron or jointly
owned with Procter & Gamble which were conceived and reduced to practice in
connection with any Procter & Gamble Retained Project at any time through
December 31, 2000 and as of December 31, 2000 have no known use in the Field or
in any Regeneron Retained Project, to make, have made, use, import, offer for
sale and sell any products for the prevention, diagnosis, or treatment of any
disease or disorder in humans or animals. Regeneron hereby grants to Procter &
Gamble a Non-Exclusive License under its Patents and Know-how which were
conceived and reduced to practice in connection with any Procter & Gamble
Retained Project at any time through December 31, 2000 and as of December 31,
2000 have known use in the Field or in any Regeneron Retained Project, to make,
have made, use, import, offer for sale and sell any products for the prevention,
diagnosis, or treatment of any disease or disorder in humans or animals in
connection with any Procter & Gamble Retained Project. Further, Regeneron shall
grant Procter & Gamble a non-exclusive, royalty-free license under Regeneron
Know-how and Regeneron Patents, without the right to sublicense, to make, have
made, and use Compounds (as defined in the Multi-Project Collaboration
Agreement) identified prior to the Research Term of the Multi-Project
Collaboration Agreement, other than MuSK or Agrin, for research utility for the
purpose of discovering, developing and/or commercializing other Compounds in the
Procter & Gamble Retained Project. This non-exclusive license does not include
the right to commercialize, i.e., have sold or sell, these identified Compounds
(as defined in the Multi-Project Collaboration Agreement), under Regeneron
Know-how and Regeneron Patents.

         (c) Regeneron grants Procter & Gamble a Non-Exclusive License under its
Patents and Know-how conceived and reduced to practice in connection with any
Mutual Retained Project at any time through December 31, 2000, to make, have
made, use, import, offer for sale and sell any products for the prevention,
diagnosis, or treatment of any disease or disorder in humans or animals.
Further, Regeneron shall grant Procter & Gamble a non-exclusive, royalty-free
license under Regeneron Know-how and Regeneron Patents, without the right to
sublicense, to make, have made, and use Compounds (as defined in the
Multi-Project Collaboration Agreement), identified prior to the Research Term of
the Multi-Project Collaboration Agreement, other than MuSK or Agrin, for
research utility for the purpose of discovering, developing and/or
commercializing other Compounds in the Mutual Retained Project. This
non-exclusive license does not include the right to [********************
***************************************] under Regeneron Know-how and
Regeneron Patents.

         (d) Subject to subsection (g) below, Procter & Gamble grants Regeneron
a Non-Exclusive License under its Patents and Know-how conceived and reduced to
practice in

                                       16
<PAGE>
connection with any Mutual Retained Project at any time through December 31,
2000, to make, have made, use, import, offer for sale and sell any products for
the prevention, diagnosis, or treatment of any disease or disorder in humans or
animals.

         (e) The Parties agree that through December 31, 2000, they will provide
research support and otherwise cooperate with one another to effect the orderly
transfer of information, rights, and licenses, including Know-how and Patents,
for all Retained Projects as set forth in subsections (b), (c) and (d) above.
Each Party shall grant the other a non-exclusive license (without any right to
sublicense) under its respective Patents and Know-how solely with respect to
these support and transfer activities. Furthermore, at any time or from time to
time after the Effective Date, at either Party's request, one Party shall
execute and deliver to the other Party such other instruments of transfer,
conveyance, assignment and confirmation and take such other actions as may be
reasonably requested in order to more effectively transfer, convey and assign
title to the respective Know-how and Patents licensed pursuant to subsections
(b), (c) and (d) above.

         (f) For purposes of this Section 2.2, (i) the term "Exclusive License"
shall mean a [******************************************************************
****************************]; (ii) the term "Non-Exclusive License" shall mean
a [*************************************************************;] and (iii) the
term non-exclusive license shall have the meaning set forth hereinabove.

         (g) The Parties agree that for purposes of Section 2.2(a) above, the
only small molecules, proteins and peptides covered by the Exclusive License and
Non-Exclusive Licenses are set forth in Attachment 2.2(g)(i) hereof.
Furthermore, the Parties agree that for purposes of Section 2.2(d) above, the
only small molecules, proteins and peptides covered by the Non-Exclusive License
are set forth in Attachment 2.2(g)(ii) hereof. However, Regeneron may use the
small molecules, proteins and peptides listed in Attachment 2.2(g)(i) and
2.2(g)(ii) for additional research utility for the purpose of discovering,
developing and/or commercializing other small molecules, proteins and
peptides(including derivatives). Should any of these other small molecules,
proteins and/or peptides fall within Procter and Gamble Patents or Know-how
conceived and/or reduced to practice prior to December 31, 2000, Procter and
Gamble agrees that it shall never, anywhere in the world, institute any action
or suit at law or in equity, or aid in the prosecution of any such claim,
against Regeneron or any of its licensees, sublicensees, suppliers,
distributors, collaborators or agents ("Regeneron Licensees") alleging
infringement of any such Procter & Gamble Patents or Know-how. Procter & Gamble
further covenants and agrees that in the event Procter & Gamble grants or
transfers any rights under any such Procter & Gamble Patents and Know-how to any
third party, such grant or transfer of rights shall be only upon the condition
that such third party agrees, in

                                       17
<PAGE>
writing, to grant Regeneron and the Regeneron Licensees immunity from suit as
set forth in this Section 2.2(g). The Parties agree that notwithstanding the
Exclusive License granted to Regeneron pursuant to Section 2.2(a) above, P&G
shall retain the non-exclusive right to use the Compounds identified in
Attachment 2.2(g)(i) hereof for research purposes outside the Regeneron
Exclusive Project to which they pertain (the "Section 2.2(g) Fields"). For
clarity, P&G's retained non-exclusive research right described above does not
include the right to commercialize, i.e. have sold or sell, the small molecules,
proteins, and peptides in Attachment 2.2(g)(i) for use in the applicable Section
2.2(g) Field.

         (h) The Parties agree that Procter & Gamble does not grant any rights
to the small molecules in the [*****************] (other than those Compounds in
the Muscle Field or DDR Field). However, should Procter & Gamble advance any
such small molecule [*****************] to the equivalent of a Lead Compound
[***************************] by June 30, 2002, Procter & Gamble shall notify
Regeneron of such [***********************]. The Parties shall meet within
thirty (30) days of notification to agree on a Product Plan or other disposition
(e.g., license to a Party or Third Party) of such [****************]. The
[******************] will be subject to the terms and conditions of this
Agreement as a Lead Compound in the Field. All funding for the
[*********************] prior to notification to Regeneron shall be borne by
Procter & Gamble.

         2.3. WAIVER OF RIGHTS. Notwithstanding anything to the contrary in any
of the Securities Agreements, in consideration of the terms and conditions of
this Agreement, each party hereby unconditionally waives any rights or remedies
under any of the Securities Agreements, or otherwise available under contract
law, arising from the agreed upon termination of the Multi-Project Agreement.
Furthermore, the Parties agree that solely for purposes of the Securities
Agreements, the Multi-Project Agreement and the Collaboration Agreement, dated
as of December 11, 1996, between the Parties shall be considered superseded, but
not terminated, by this Agreement.

         2.4.     SCOPE OF COLLABORATION.

         (a) The Parties will work together to research, develop and
commercialize Lead Compounds pursuant to this Agreement in the Territory. All
such work shall be conducted pursuant to a Research Collaboration Plan and
Product Plans established by the OC pursuant to Article III. The Parties shall
use Commercially Reasonable Efforts in performing their obligations under this
Agreement.

         (b) Work under this Agreement will include work only in the Muscle
Field, the GPCR Field and the DDR Field.

                                       18
<PAGE>
         (c) Subject to the provisions of a Research Project Plan or Research
Collaboration Plan, the primary responsibilities for the activities shall be
established and agreed to in the Research Project Plan.

         (d) The Parties will also work together to develop and market
Development Compounds and Marketed Compounds in the Territory in accordance with
Product Plans.

         (e) If, at any time during the Research Term, the PC decides to
discontinue research on a GPCR and remove it from the GPCR Field, Regeneron
shall own all rights to the specific GPCR (a "Returned GPCR"), including all
Patents and Know-how specifically relating to the Returned GPCR conceived or
reduced to practice before or during the Research Term. A GPCR will be removed
from the GPCR Field if it is not subject to any active or future planned
research activities under the Research Project Plan and Regeneron provides
information to the PC of the GPCR's potential utility in a therapeutic area
outside of P&G's fields of interest. The Returned GPCR(s) shall be considered
outside the GPCR Field and may be progressed by Regeneron independently or with
a Third Party subject to the terms of this Agreement. For a Returned GPCR that
Regeneron progresses either independently or with a Third Party, the following
royalty shall be paid to Procter & Gamble:

                  (1)      [*************] for any Returned GPCR progressed
                           under the Agreement wherein a transgenic (knock-in or
                           knock-out) has been created pursuant to the Research
                           Project Plan; or

                  (2)      [***********] for any Returned GPCR progressed under
                           the Agreement wherein an antagonist or agonist
                           (biological or small molecule) is commercialized
                           which has been identified prior to the date the GPCR
                           is returned.

         (f) Regeneron shall have the right to develop any GPCR outside the GPCR
Field on its own or with any third parties. However, should Regeneron during the
Research Term of this Agreement discover that a GPCR has utility in the Muscle
Field, the GPCR will be subject to the terms and conditions of this Agreement.
For the avoidance of doubt, if the GPCR in question is owned or controlled, in
whole, or in part, by a Third Party collaborator of Regeneron, Regeneron shall
discontinue further development of the GPCR in the Muscle Field. In addition, if
Regeneron independently develops a GPCR outside the GPCR Field to the
pre-clinical stage (i.e. equivalent to Success Criteria for Research Compounds)
and to the extent Regeneron wishes to partner said GPCR, P&G will have the right
of first negotiation to be the development partner for said GPCR at any time
prior to the initiation of the IND process (subject to the terms of Section
5.4(c)).

         2.5.     COMMITTEE MEMBERSHIP.

                                       19
<PAGE>
         (a) OC Membership. The work under this Agreement, as set forth in
Section 2.4, shall be performed by the Parties pursuant to the oversight of the
OC. The OC has overall responsibility for the collaboration. The OC may delegate
its responsibilities to other committees (e.g., to a Program Committee as
established pursuant to Section 2.5(b), to a Development Committee as
established pursuant to section 2.5(c) or to a Patent Committee, Research
Committee, Finance Committee, Clinical Committee or such other committees as the
OC may establish); however, the OC may not delegate Major Decisions. The OC will
initially consist of two (2) members with one (1) member designated by each
Party. The initial members are listed on Attachment 2.5(a). A chairperson of the
OC will be nominated alternately by Procter & Gamble and Regeneron to twelve
(12) month terms. The Parties will be free to change their respective
representatives, on notice to the other Party. The OC will exist until the
earlier of termination or expiration of this Agreement or when one Party is an
Opting Out Party with respect to all Compounds in all countries, unless the
Parties otherwise agree.

         (b) PC Membership. A Program Committee is also hereby established and
shall work pursuant to the oversight of the OC. The PC shall develop and propose
the Research Collaboration Plan, as well as a plan for any other Major
Decisions, for the OC's review and approval. Upon the OC's approval of such
Research Collaboration Plan or Major Decision, the PC is responsible for
managing such matters and reporting to the OC on a regular basis. The PC shall
also develop and propose the Research Project Plans. The membership of the PC
shall consist of six (6) members, with three (3) members designated by each
Party. The method for the nomination of the chairperson of the PC shall be the
same as that for the OC as described in Section 2.5(a). The initial members of
the PC are listed on Attachment 2.5(b).

         (c) Development Committee. The Parties shall establish a Development
Committee composed of representatives of both Parties which shall be responsible
for managing work on each Development Compound pursuant to the Product Plan for
such Development Compound and subject to the oversight of the OC. The
Development Committee shall draft the Product Plan and annual updates to the
Product Plan for each Development Compound and submit such drafts as well as a
plan for any Major Decisions concerning such Development Compound to the OC for
approval. Upon the OC's approval of a Product Plan or Major Decision for a
particular Development Compound, the DC is responsible for managing such matters
and reporting to the OC on a regular basis. The DC may delegate responsibility
for the day-to-day management of a particular Development Compound to a sub-team
comprised of members from both Parties. The membership of the DC shall be as
agreed by the Parties, and shall consist of an equal

                                       20
<PAGE>
number of representatives from each Party. The initial members of the DC are
listed on Attachment 2.5(c).

         2.6. MEETINGS. The OC will meet at least one (1) time per Fiscal Year
and the PC will meet at least four (4) times per Fiscal Year, and either or both
committees may meet at additional times as the Parties shall agree. The DC shall
meet at such times as the Parties shall agree. Either Party may call a special
meeting of the OC up to two (2) times per Fiscal Year, on fifteen (15) days'
written notice to the other Party. Additionally, the OC shall meet within twenty
(20) business days of the PC's or DC's request to approve any Major Decisions.
The chairperson shall send to all OC or PC members (as the case may be) notices
of all regular meetings and agendas for such meetings. The Party convening a
special meeting shall send notices and agenda for such meeting. Meetings will
alternate between the offices of the Parties, or may be held via teleconference,
videoconference or such other place or manner as the Parties may mutually agree.
Members of the OC, PC and DC shall be empowered to make decisions within the
scope of their respective committee responsibilities and shall have the right to
participate in and vote at meetings in person, by telephone, by videoconference
or by proxy. The Party hosting any meeting shall appoint a secretary to the
meeting who will record the minutes of the meeting which will be circulated to
the members of the OC, PC or DC (as the case may be) promptly following the
meeting for review, comment, and adoption.

         2.7. DECISION-MAKING CRITERIA. All decisions of the OC, PC and DC shall
be made by majority vote and in the exercise of good faith. Such decisions shall
adhere to the ethical and legal standards for the research-based pharmaceutical
industry and utilize Commercially Reasonable Efforts to research, develop, and
commercialize Compounds in the Field.

        Notwithstanding the foregoing regarding a majority vote, Procter &
Gamble shall have the tie-breaking vote in the OC and PC with respect to: (i)
any strategic and/or funding/budgeting issues with respect to the Research
Collaboration Plan where Procter & Gamble determines in good faith that there is
the likelihood that Targets proposed by Regeneron may become Excluded Technology
as defined in Section 1.14, (ii) any Third Party costs which are the
responsibility of Procter & Gamble pursuant to Section 3.2 and (iii) decisions
made pursuant to Section 4.1. Regeneron shall have the tie-breaking vote in the
OC and PC with respect to allocating Regeneron research FTEs within the scope of
an approved Research Collaboration Plan.

                                       21
<PAGE>
         2.8. DISPUTE RESOLUTION. Subject to Section 2.7, if a decision cannot
be achieved by the PC or DC, the matter shall be referred to further review and
resolution by the OC. If the OC cannot resolve the matter within thirty (30)
days, the OC shall refer the matter to the Chairman or CEO of Regeneron and the
President of Procter & Gamble Pharmaceuticals (the "CEOs"), if both CEOs were
not voting members of the OC. If the CEOs (or the OC, if the CEOs are both
voting members) cannot resolve the issue within thirty (30) days, the CEOs shall
mutually agree upon and appoint to the OC a "Temporary Member." "Temporary
Member" means a person who is knowledgeable in the research based pharmaceutical
industry, possessing senior executive experience and skills and not associated
with either Party or a competitor of either Party. If the CEOs cannot mutually
agree on the identity of such Temporary Member within fifteen (15) days of the
end of such thirty (30) day period, the Parties shall request an arbitral panel
composed in accordance with Section 11.4, sitting in Boston, Mass., to, and such
panel shall, appoint to the OC a Temporary Member. The OC shall meet and resolve
the dispute within one week of such appointment of the Temporary Member. All
decisions with respect to the issue in dispute shall be made by majority vote of
the OC. Such Temporary Member shall be appointed to the OC until such time as
the CEOs mutually agree that the dispute or disputes have been resolved or until
one Party is deemed to be an Opting Out Party with respect to such Compound (and
country, if applicable) at issue, whichever is earlier. Such Temporary Member
shall be instructed to render his or her votes consistent with the stated
decision-making criteria of the OC, as set forth in Section 2.7. The Parties
shall share equally in all costs associated with the appointment of the
Temporary Member. Notwithstanding the foregoing, any disputes, with respect to
approving (or not approving) a Research Collaboration Plan or negotiating a J-V
Agreement shall be resolved by the Temporary Member voting for one Party's
proposed Research Collaboration Plan or J-V Agreement, as the case may be.

         2.9. CONDUCT OF WORK BY OTHERS. It is understood that each Party has
entered into this Agreement based on the specific experience and skill of the
other Party. Accordingly, it is anticipated that work under this Agreement will
be conducted primarily by the Parties. However, it may be commercially
reasonable for the Parties to enter into agreements with commercial or
non-commercial Third Parties to acquire technology or conduct certain aspects of
such work (e.g., because the Third Party's work provides a favorable
cost/benefit vs. utilizing internal resources). Such agreements may include
(without limitation), acquisition of research methods, Compounds or intellectual
property rights (if applicable), consultation, conduct of certain research
tests, chemical synthesis and supply, safety testing, clinical testing, and
marketing support. All such work by or

                                       22
<PAGE>
acquisition from Third Parties shall be conducted pursuant to the Research
Collaboration Plan and/or Product Plan and shall be performed pursuant to
written agreements embodying confidentiality, intellectual property rights and
other terms consistent with the terms set forth in this Agreement. To the extent
commercially reasonable, the commercial or non-commercial Third Parties will be
obligated to assign or exclusively license any patents, patent applications or
know-how under terms that are mutually agreeable to the Parties. Information
obtained by a Party from any Third Party shall be subject to Article VIII of
this Agreement. All technology obtained from a Third Party pursuant to this
Section 2.9 shall be, to the extent possible under commercially reasonable
terms, jointly owned by the Parties and shall be subject to Articles V and VII.

         2.10. RECORD-KEEPING. All committees shall appoint one Party to keep
complete and accurate records pertaining to the Parties' activities hereunder.
The other Party shall have the right to review such records upon reasonable
notice to the recordkeeping party and at reasonable times. Such records are
subject to audit by the other Party pursuant to Section 6.5 within a reasonable
period after the end of the Fiscal Year. In addition, the recordkeeping party
shall prepare quarterly unaudited financials pertaining to such activities,
which shall be distributed to the Parties within thirty (30) days of the end of
such period.

         2.11.    NON-COMPETE.

         (a) During the Research Term, neither Party will, independently of the
other, perform research in the Field.

         (b) During the Research Term and for five (5) years thereafter, neither
Party may directly or indirectly develop, including without limitation the
performance of clinical trials, or commercialize a Competing Product in the
Territory.

         (c) Notwithstanding anything to the contrary contained in this
Agreement, the Parties agree that Excluded Technology is not included within the
scope of this Agreement. In particular, nothing in this Agreement shall prohibit
either Party from performing research, developing or marketing compounds or
products using its own Excluded Technology

         2.12. BOARD REPRESENTATION. Regeneron will uses its best efforts to put
a person representing Procter & Gamble (a "P&G Director") on Regeneron's Board
of Directors sixty (60) days after Regeneron receives written notice from
Procter & Gamble at any time during the Term. The Parties shall work together to
identify a mutually agreeable P&G Director; however, if the Parties cannot agree
upon a P&G Director within thirty (30) days

                                       23
<PAGE>
of Regeneron's receipt of Procter & Gamble's written notice, Procter & Gamble
shall designate an officer of Procter & Gamble as a P&G Director and Regeneron
shall uses its best efforts to have such P&G Director appointed or nominated and
elected as a Director on Regeneron's Board of Directors. Notwithstanding
anything to the contrary, Regeneron shall have no obligation pursuant to this
Agreement to take any action that would result in more than one P&G Director
sitting on Regeneron's Board of Directors at any one time, nor shall Regeneron
have any obligations with respect to appointing or nominating a P&G Director
under this Section 2.12 so long as Procter & Gamble owns less than
[****************] of Regeneron's Outstanding Securities (as defined in the
Securities Purchase Agreement dated May 13, 1997 between Procter & Gamble and
Regeneron and as amended from time to time).

                     ARTICLE III - RESEARCH AND DEVELOPMENT

         3.1. RESEARCH COLLABORATION PLAN. The Parties will agree to a Research
Collaboration Plan. The OC is authorized to approve and amend the Research
Collaboration Plan. During the Research Term, the Research Collaboration Plan
budget shall include FTE allocations and any Third Party costs. The timing and
calculations for the Research Collaboration Plan budget are contained in
Attachment 3.1.

         3.2.     FUNDING OF RESEARCH COLLABORATION PLAN.

         (a) During the Research Term, Regeneron shall provide [*******]
Regeneron research FTEs per year for Regeneron's work pursuant to the Research
Collaboration Plan. Unless otherwise agreed to by the parties, Procter & Gamble
shall make payments quarterly, in arrears to Regeneron equal to [**********] per
calendar quarter through December 31, 2005, subject to the adjustments
contemplated in the paragraph below.

         An Inflation Payment Adjustment shall be made quarterly beginning with
the quarter ending September 30, 2001. Such Inflation Payment Adjustment shall
be based on Regeneron's annual cost per research FTE of
[***********************************] ("FTE Rate"). The FTE Rate includes costs
such as those listed in Attachment 3.2. The Inflation Payment Adjustment shall
be calculated by multiplying [****] Regeneron research FTEs by the FTE Rate
Adjustment, which is defined as the quarterly equivalent of the FTE Rate
multiplied by the percentage change (rounded to the nearest tenth of a percent)
between the Consumer Price Index for All Urban Consumers as published by the
U.S. Bureau of Labor Statistics ("CPI") for June 2000 versus the CPI for the
month of June immediately preceding the Fiscal Year in which such payments are
applicable. The calculation for and examples of such Inflation Payment
Adjustments are detailed in Attachment 3.2. Regeneron shall use funding provided
under this Section 3.2 solely for

                                       24
<PAGE>
carrying out the Research Collaboration Plan. Regeneron shall submit a report to
Procter & Gamble within [***************] after the end of each Fiscal Quarter
detailing the number of FTEs performing work pursuant to the Research
Collaboration Plan and detailed description of such work. Regeneron shall submit
invoices to Procter & Gamble pursuant to this Section 3.2(a), including, if
applicable, a calculation of any amounts payable as Inflation Payment
Adjustments, quarterly in arrears. Invoices submitted to Procter & Gamble
pursuant to this Section are payable net [************] days after receipt and
are subject to Procter & Gamble's audit pursuant to Section 6.5.

         (b) All costs associated with work by Procter & Gamble pursuant to the
Research Collaboration Plan shall be borne by Procter & Gamble. In addition,
Procter & Gamble shall pay for all Third Party costs for which it approves in
its sole discretion.

         (c) If a Lead Compound is identified by either or both Parties during
the Tail Period, the Parties shall meet within [****************] days of such
identification to agree on a Product Plan or other disposition (e.g., Opt out,
license to a Party or Third Party) of such Lead Compound. The Lead Compound will
be subject to the terms and conditions, including funding obligations required
in this Agreement and shall be considered a Lead Compound in the Field. The Tail
Period Term shall be terminated by the OC's approval or as otherwise agreed by
the Parties.

         3.3. SELECTION OF DEVELOPMENT COMPOUNDS.  When a Research Compound has
been demonstrated to meet the Success Criteria, the Compound shall be designated
a Development Compound. Within ninety (90) days after the designation of a
Development Compound by the Parties, the OC shall approve a Product Plan for
such Development Compound. The Product Plan shall include
[*******************************************************************************
********************************************************************************
*************************************************************************] Each
Product Plan should incorporate those elements set forth in Attachment 3.3.
[******************************************************] The timing and
calculations for the typical Product Plan budget is contained in Attachment 3.1
as an example. The OC will have complete authority to adopt all Product Plans.

         3.4. FUNDING OF DEVELOPMENT COMPOUNDS AND MARKETED COMPOUNDS; OPTING
OUT.

         (a) Allowable Product Expenses.
********************************************************************************
********************************************************************************

                                       25
<PAGE>
*******************************************************************************
***********************************************************]

         (b) Either Party may, at any time during the Term, become an Opting Out
Party with respect to a Lead Compound, Development Compound or Marketed
Compound, either in total or on a country-by-country basis pursuant to Section
3.6. [*************************************************************************
***********************************************************************] The
Opting Out Party shall grant licenses to the Proceeding Party pursuant to
Section 5.5. Royalties paid pursuant to such licenses shall be made pursuant
to Article VI.

         (c) If both Parties are Opting Out Parties with respect to a Lead
Compound, Development Compound or Marketed Compound pursuant to Section 3.4(b),
[*******************************************************************************
********************].

         (d) Procter & Gamble shall not be deemed an Opting Out party for
[*******************************************************************************
********************************************************************************
*********************************************************]

         3.5. RESEARCH, DEVELOPMENT AND MARKETING COMMUNICATION. In addition to
Regeneron's reporting obligations under Section 3.2(a), Regeneron and Procter &
Gamble will submit reports to each other not less than two (2) times per Fiscal
Year presenting a meaningful summary of research, development and marketing
activities performed under this Agreement. Regeneron and Procter & Gamble will
make presentations of such activities to each other, beyond that made to the OC,
as reasonably requested by each other. All technology generated by the Parties
shall be disclosed pursuant to Section 7.1. The Parties shall use their best
efforts to communicate information only within the scope of this Agreement.
Regeneron and Procter & Gamble will also communicate informally and through the
OC to inform each other of research and development done under this Agreement.
Regeneron and Procter & Gamble will provide each other with raw data in original
form or a photocopy thereof for any and all work carried out under this
Agreement as reasonably requested by the other. Any information contained in
such reports and as otherwise communicated by Regeneron or Procter & Gamble is
subject to Article VIII. If one Party is deemed an Opting Out Party, the
Proceeding Party shall annually report to the Opting Out Party research,
development and marketing activities performed for Compounds in the Territory
for the prior Fiscal Year sufficient to allow the Opting Out

                                       26
<PAGE>
Party to determine whether the Proceeding Party is utilizing Commercially
Reasonable Efforts.

         3.6. GLOBAL DEVELOPMENT. The Product Plan shall set forth commercially
reasonable development work (including without limitation clinical studies) to
support acceptable regulatory applications for marketing clearance in all Major
Countries. The costs associated with these activities shall be deemed "Global
Expenses." If either Party fails to pay its share of Global Expenses with
respect to a Compound, such Party shall be deemed an Opting Out Party with
respect to such Compound in the entire Territory pursuant to Section 3.4(b).
Either Party may Opt Out of the commercialization of a Compound on a
country-by-country basis provided it funds its share of total Global Expenses,
to the extent that funding of any development and/or marketing expenses is
solely attributable to one country and is not considered a Global Expense
("Country Expenses"). A Party that does not pay such Country Expenses shall be
deemed an Opting Out Party with respect to such Compound in that particular
country only pursuant to Section 3.4(b).

         3.7. J-V FORMATION. Commencing at the [****************************
************************************] the Parties shall negotiate in good faith
an agreement that contains all of the terms and conditions of this Agreement,
along with other terms and conditions as the Parties may agree to develop and/or
market Compounds, including without limitation reasonable non-compete provisions
("J-V Agreement"). In the event that the Parties cannot finalize such J-V
Agreement within [************] the Parties may commence dispute resolution
pursuant to Section 2.8 or the Parties may elect to continue to perform
development and marketing activities pursuant to this Agreement until its
termination, or negotiate such other arrangement as the Parties may agree.

         3.8. SUMITOMO COMPOUNDS. Regeneron shall, subject to the
confidentiality provisions of Article VIII, have the right to disclose to
Sumitomo Chemical Company Limited and its affiliates (herein "Sumitomo")
information regarding a Compound solely conceived and reduced to practice by
Regeneron solely for the purpose of, and to the extent necessary for, enabling
Regeneron to fulfill its obligations under the Sumitomo Agreement.
********************************************************************************
********************************************************************************
********************************************************************************
*******************************************

                                       27
<PAGE>
         3.9. REGULATORY RESPONSIBILITY. As part of the Product Plan for each
Development Compound, the DC shall assign responsibility for the preparation and
filing of Health Registrations for such Development Compound. The Parties shall
consult and cooperate in obtaining all Health Registrations.

         3.10. COMMUNICATION WITH REGULATORY AUTHORITIES. The Party assigned
regulatory responsibility for a particular Health Registration for a Development
Compound shall have primary responsibility for communications with respect to
the regulatory authorities having jurisdiction over such Health Registration for
the Development Compound. Both Parties shall have the right to participate in
all meetings with regulatory authorities. The Party that is not assigned
regulatory responsibility for a particular Health Registration for a Development
Compound shall have the right to review all correspondence to the applicable
regulatory authority prior to submission, unless such correspondence is of a
routine nature or is an Adverse Experience report required by applicable law or
regulation. Copies of all written correspondence submitted by either Party to
regulatory authorities or written reports of discussions with regulatory
authorities shall be sent to the other Party promptly after such submission or
discussion. The Parties shall enter into further agreement or agreeable standard
operating procedures to ensure rapid communication between the Parties regarding
all communication to and from regulatory authorities.

         3.11. OWNERSHIP OF INDS.

         (a) Regeneron will own the IND or foreign equivalent for each
Development Compound that is a protein and that is manufactured by Regeneron.

         (b) P&G will own the IND or foreign equivalent for each Development
Compound that is a small molecule and that is manufactured by P&G.

         (c) For all other Development Compounds, the Party assigned primary
responsibility for the execution of the clinical program shall own the IND or
foreign equivalent.

         (d) If the Party that owns the IND or foreign equivalent for a
particular Development Compound is not assigned primary responsibility for the
execution of the clinical program for such Development Compound, the Parties
will enter into further agreement or agreeable standard operating procedures to
ensure direct communication between FDA or other regulatory agency and the Party
assigned primary responsibility for the execution of the clinical program
regarding all clinical matters.

         3.12. ADVERSE EXPERIENCES.

                                       28
<PAGE>
         (a) Reporting Responsibilities. Adverse Experiences reported in respect
of a particular Development Compound shall be reported to the appropriate
regulatory authorities by the Party required to report such Adverse Experiences
under the laws and regulations of each country in the Territory. "Adverse
Experience" shall have the meaning set forth in current ICH guideline.

         (b) Safety Representatives. Each Party will provide to the other the
name of an appointed safety representative of the Party to whom all adverse
Experiences reports and queries should be reported. The safety representative of
each Party will report to the safety representative of the other Party all
Adverse Experiences received in respect of a particular Development Compound as
follows:

         (i)      Without regard to investigator-ascribed causality, any and
                  every Adverse Experience which is fatal or life threatening or
                  which is a serious Adverse Experience as defined in clinical
                  protocols shall be reported by the receiving party to the
                  other Party by facsimile within one (1) working day of receipt
                  by the receiving Party's safety representative;

         (ii)     A summary written report of all non-serious Adverse
                  Experiences shall be submitted by the receiving Party to the
                  other Party on a monthly basis by the receiving Party's safety
                  representative;

         (iii)    A summary written report of all Adverse Experiences, serious
                  and non-serious shall be provided by each Party to the other
                  Party, on an annual basis, indicating those cases which have
                  previously been reported to the other Party;

         (iv)     Any information which changes an Adverse Experience from
                  non-serious to serious shall be reported to the other Party's
                  safety representative within one (1) working day of receipt of
                  such information by the receiving Party's safety
                  representative;

         (v)      Further information received by a Party on any serious Adverse
                  Experience shall be reported to the other Party's safety
                  representative within ten (10) working days of receipt of such
                  information by the receiving Party's safety representative;
                  and

         (vi)     Treatment codes shall be included in all reports for any
                  Adverse Experiences that must be reported to European
                  regulatory authorities.

         (c) Serious Adverse Experiences. For purposes of this Agreement, an
Adverse Experience will be considered "serious" according to the then-current
ICH and FDA criteria as well as any event defined as a serious Adverse
Experience by the relevant study protocol.

                                       29
<PAGE>
                       ARTICLE IV - MARKETING OF PRODUCTS

         4.1.     MARKETING AND SALES STRATEGY.  [****************************
********************************************************************************
********************************************************************************
********************************************************************************
************************************************]

         4.2. NET PROFITS. The Parties, so long as neither Party is an Opting
Out Party with respect to such Marketed Compound either in the entire Territory
or in one or more specific countries, as appropriate, will share equally in the
Net Profits of each Compound sold. "Net Profits" mean Net Sales less Allowable
Product Expenses.

         4.3. EXCLUSIVE DISTRIBUTOR. The OC may appoint either Party or a Third
Party to act as its agent in connection with the marketing, sale and
distribution of Marketed Compounds, and the OC and/or the Parties (as the case
may be) shall grant to such agent(s) appropriate authority to perform its or
their responsibilities hereunder. In connection with such marketing, sales and
distribution, the following principles shall apply:

              (a) the business objective will be to maximize overall profits;
       and

              (b) in the event that a Third Party is appointed as the Parties'
       agent with respect to the marketing, sale and distribution of the
       Marketed Compound in a country, Regeneron and Procter & Gamble will each
       receive equal shares of any revenue received from such Third Party, so
       long as neither Party is an Opting Out Party with respect to such
       Marketed Compound in such country.

         4.4. REGENERON CO-PROMOTION ACTIVITIES. Provided that Regeneron is not
an Opting Out Party with respect to the Compound, Regeneron will have an equal
right and opportunity, but not the obligation, to participate in the sales and
marketing efforts in any country in the Territory as to which it has not Opted
Out by supplying up to [*****************] of a Marketed Compound's sales and
marketing efforts with notice to Procter & Gamble within [********] of the OC's
decision to prepare a regulatory application for marketing clearance in the
first Major Country with respect to all Major Countries, then on a
country-by-country basis upon regulatory filings in such countries other than
Major Countries. Regeneron's and Procter & Gamble's sales and marketing
personnel costs shall be an Allowable Product Expense and shall be calculated
for both

                                       30
<PAGE>
Parties on the same basis (e.g., the cost per salesperson or sales call for
Regeneron and Procter & Gamble shall be the same per year). If the Parties want
to discontinue or decrease its promotion activities, it must give the other
Party [*********] notice prior to such discontinuation or decrease. Either
Party's choice to not promote a Marketed Compound shall not cause such Party to
be an Opting Out Party with respect to such Marketed Compound, so long as such
Party meets its funding obligations pursuant to Section 3.4.

         4.5. TRADEMARKS; PACKAGING. After a Compound has been designated a
Development Compound, the Parties shall jointly develop a trademark for such
Development Compound. So long as it is not an Opting Out Party with respect to
such Compound in a country, Procter & Gamble shall file, prosecute and maintain
all trademark applications and registrations for such trademarks. Procter &
Gamble shall pay all expenses in connection with filing and prosecution of such
trademarks. All other costs associated with such trademarks shall be deemed
Allowable Product Expenses. As long as neither Party is an Opting Out Party with
respect to the Marketed Compound, such Marketed Compound shall be sold under a
single trademark which shall be owned by Procter & Gamble (and Procter & Gamble
shall grant Regeneron a royalty-free license to such trademark(s) if Regeneron
promotes a Marketed Compound pursuant to Section 4.4) or, if a legal entity is
formed pursuant to a J-V Agreement, the trademark shall be owned by such entity
to the extent legally permissible. If one Party is an Opting Out Party with
respect to such Marketed Compound, any trademarks shall be owned by the
Proceeding Party. So long as neither Party is an Opting Out Party, the label of
the Marketed Compound will contain the name of Regeneron and Procter & Gamble,
to the extent legally permissible.

                           ARTICLE V - LICENSE GRANTS

         5.1 RIGHTS IN TECHNOLOGY DEVELOPED DURING AGREEMENT. Patents and
Know-how regarding all Inventions, shall be owned:

         (a) by P&G, if such technology is conceived and reduced to practice
solely by employees of P & G;

         (b) jointly, if such technology is conceived and/or reduced to practice
jointly by employees of P&G and Regeneron; and

         (c) by Regeneron, if such technology is conceived and reduced to
practice solely by employees of Regeneron.

                                       31

<PAGE>
         Inventorship shall be determined according to the laws of the United
States. Filing, prosecution, maintenance and enforcement of such Patents shall
be handled pursuant to Article VII. Except as specifically set forth in this
Agreement, no Party shall have any rights to Patents or Know-how owned solely by
the other Party.

         5.2 LICENSE GRANTS DURING RESEARCH TERM - INVENTIONS HAVING UTILITY IN
             THE FIELD.

         (a) P&G hereby grants Regeneron a Sole License under P&G Patent Rights
and P&G Know-how to make, have made, use, import, offer for sale and sell P&G
Technology in the Field. The Sole License shall be royalty free for uses in the
Field. P&G also hereby grants Regeneron, for research purposes only in the
Field, a Sole License under P&G Patent Rights and P&G Know-how to make, have
made, and use small molecule Research Compounds that have not met Success
Criteria.

         (b) Regeneron hereby grants P&G a Sole License under Regeneron Patent
Rights and Regeneron Know-how to make, have made, use, import, offer for sale
and sell Regeneron Technology in the Field. The Sole License shall be royalty
free for uses in the Field.

         (c) The licenses granted in Sections 5.2(a) and (b) above will not be
used by either Party independent of this Agreement.

         (d) As used herein, "Sole License" shall mean a non-exclusive license
in the Territory under Know-how or a Patent, without the right to sublicense,
granted by a "Licensor Party" to the other "Licensee Party" in the Field,
wherein the Licensor Party shall not grant any Third Party rights in the Field
under the Know-how or Patent to the subject matter of the license.

         (e) With respect to Inventions made as a direct result of work done
under this Agreement during the Research Term and owned solely or jointly by a
Party wherein the Invention has utility in the Field, each Party grants to the
other the right of first negotiation to obtain from the other Party exclusive
rights outside the Field in the Territory under reasonable terms for any such
Invention. This "right of first negotiation" shall be in effect during the
Research Term. For sole Inventions that a Party wishes to partner or out
license, the "rights of first negotiation" shall operate as set forth in Section
5.4(c).

         5.3 RIGHTS UPON TERMINATION OF THE RESEARCH TERM - INVENTIONS HAVING
             UTILITY IN THE FIELD.

         (a) Upon expiration of the Research Term, the Sole Licenses and rights
of first negotiation granted by the Parties under Section 5.2 shall terminate.
However, the Parties

                                       32
<PAGE>
grant the license rights set forth in Sections 5.3(b) and (c) on expiration of
the Research Term.

         (b) With respect to Procter & Gamble Inventions having a utility in the
Field, P&G shall grant Regeneron a non-exclusive, royalty-free license under
Procter & Gamble Know-how and P&G Patent Rights, without the right to
sublicense, to make, have made, and use P&G Technology for the purpose of
discovering, developing and/or commercializing Compounds (other than small
molecules, DNA sequences, proteins and peptides that are covered by Procter &
Gamble Inventions identified during the Research Term or Tail Period ("Procter &
Gamble Compounds")) in the Field. In addition, P&G shall grant to Regeneron a
non-exclusive, royalty free license under Procter & Gamble Know-how and P&G
Patent Rights, without the right to sublicense, to make, have made, and use
Procter & Gamble Compounds solely for research purposes. For clarity, this
non-exclusive license to Procter & Gamble Technology and Procter & Gamble
Compounds does not include the right to have sold or sell Procter & Gamble
Technology and Procter & Gamble Compounds, under Procter & Gamble Know-how and
P&G Patent Rights.

         (c) With respect to Regeneron Inventions having utility in the Field,
Regeneron shall grant Procter & Gamble a non-exclusive, royalty-free license
under Regeneron Know-how and Regeneron Patent Rights, without the right to
sublicense, to make, have made, and use Regeneron Technology for the purpose of
discovering, developing and/or commercializing Compounds (other than Compounds
that are small molecule Research compounds, DNA sequences, proteins or peptides
covered by Regeneron Inventions identified during the Research Term or the Tail
Period ("Regeneron Compounds")) in the Field. This non-exclusive license does
not include the right to have sold or sell Regeneron Technology, including,
without limitation, Regeneron Compounds, under Regeneron Know-how and Regeneron
Patents.

         (d) Pursuant to Section 5.6, Procter & Gamble and Regeneron hereby
grant to one another for the Term a Sole License in the Territory to Patents and
Know-how directly relating to and necessary to make, have made, use, import,
offer for sale, and sell Development Compounds and the corresponding Validated
Targets. In addition, further to the rights granted elsewhere in this Section
5.3, Procter & Gamble and Regeneron hereby grant to one another a non-exclusive,
royalty-free license in the Territory to Patents and Know-how or other general
application technology that either Party owns or acquires from a Third Party
with the right to sublicense to the extent necessary to make, have made, use,
import, offer for sale, and sell Development Compounds and/or Validated Targets
in the Territory. Such general applications may include, but are not limited to,
dosage form, reagents, and or cloning methods.

                                       33
<PAGE>
         (e) Neither Party shall file an Abbreviated New Drug Application
("ANDA") in the U.S. or an equivalent foreign application for generic approval
for marketing of a Compound using the licenses under this Section.

         5.4 LICENSE GRANTS TO INVENTIONS HAVING NO UTILITY IN THE FIELD. With
respect to Inventions (i) for which there is no known utility in the Field, (ii)
that are made as a direct result of work performed under this Agreement and
(iii) for which there are no license obligations to Third Parties prohibiting
the grant of licenses set forth below, the parties agree that subject to (a) and
(b) below, each Party shall have the right of first negotiation to obtain
exclusive rights outside the Field and in the Territory under reasonable terms
consistent with those set forth herein for any such Invention owned jointly with
the other Party.

         (a) Procter & Gamble shall have the right of first negotiation to
obtain exclusive rights outside the Field and in the Territory under reasonable
terms consistent with those set forth herein for any such Invention having
[******************] owned solely by Regeneron or its Affiliates.

         (b) Regeneron shall have the right of first negotiation to obtain
exclusive rights outside the Field and in the Territory under reasonable terms
consistent with those set forth herein for any such Invention having
[*****************************************************] owned solely by P&G or
its Affiliates.

         (c) The "rights of first negotiation" referred to above in this Section
5.4(a) and (b) and previously in Section 5.2(c) shall operate as follows: The
Party that discovered the Invention (the "Discovering Party") shall notify the
other Party (the "Other Party") that it intends to partner in developing and/or
marketing the Invention and other material information concerning the applicable
Invention (the "Non-Field Invention Notice"). Within thirty (30) days after
receipt of the Non-Field Invention Notice, the Other Party will notify the
Discovering Party if it wishes to negotiate the terms of research, development
and/or marketing agreement between the Parties with respect to such Invention.
The Parties shall then negotiate in good faith to agree upon the terms of any
such agreement, provided that no Party shall have any obligation to enter into a
final binding agreement or letter of intent. During this period, the Discovering
Party shall respond to all reasonable inquiries by the Other Party concerning
the applicable Invention. The information disclosed to the Other Party in the
Non-Field Invention Notice and during this negotiation period concerning the
Invention shall be considered Information pursuant to Section 8.1 of this
Agreement. In the event that the Parties have not entered into a

                                       34
<PAGE>
further agreement (which may include a binding letter of intent in lieu of a
final agreement) on or before sixty (60) days after the delivery of the
Non-Field Invention Notice to the Other Party, the Discovering Party shall have
no obligations to the Other Party, and the Other Party shall have no rights,
with respect to the use of the applicable Invention.

         5.5 GRANT OF LICENSE BY OPTING OUT PARTY. In the event a Party becomes
an Opting Out Party with respect to a Development Compound in its entirety or on
a country-by-country basis, then the license granted by the Opting Out Party to
the Proceeding Party shall be an exclusive license including as to the Opting
Out Party, with the right to sublicense, to make, have made, use, import and
sell such Development Compound under the Patents, Know-how, trademarks and
copyrights regarding that Compound owned in whole or in part by the Opting Out
Party. The license shall be in all countries of the Territory in which Opting
Out has been deemed to occur, and shall be subject to a royalty as set forth in
Section 6.1. The Opting Out Party shall comply with reasonable requests for
cooperation by the Proceeding Party, and the Proceeding Party shall reimburse
the Opting Out Party for reasonable out-of-pocket expenses incurred with respect
to such cooperation.

         5.6 RIGHTS IN COMPOUNDS UNDER RESEARCH, DEVELOPMENT AND MARKETING. A
Party shall not grant any license to a Third Party in the Territory under any
Patent or Know-how owned in whole or in part by that Party to make, have made,
use, import or sell any Compounds that are the subject of joint research,
development or marketing by the Parties under this Agreement or any J-V
Agreement.

                      ARTICLE VI - ROYALTIES AND ACCOUNTING

         6.1. ROYALTY CALCULATION.

         (a) The Proceeding Party will pay to the Opting Out Party a royalty on
Net Sales of a Marketed Compound on a country-by-country basis, sold by the
Proceeding Party, its Affiliates, licensees and/or sublicensees in the Territory
at the applicable rate listed below multiplied by the Net Sales in such country:

                                       35
<PAGE>
<TABLE>
<CAPTION>
                Opt Out Time                                     Royalty
                ------------                                     -------
<S>                                                              <C>
[************************************                             [****]
*************************************
*************************************
*************************************
*************************************
*************************************
*************************************
**********************************
*************************************                             [****]
*************************************
*************************************
************************************
[************************************                             [****]
*************************************
*************************************
*************************************
[************************************                             [****]
*************************************
***********************************]
</TABLE>

      Such royalty will be paid for a period of [*********] years from the date
of first sale to a customer of such Compound in a particular country, or for so
long as the manufacture, use, importation or sale of the Compound would, but for
the licenses granted herein, infringe a Valid Claim of a licensed Patent in such
country, whichever is longer.

         (b) If the Parties license the Development or Marketed Compound to a
Third Party pursuant to Section 3.4(c)[***************************************
*******************************************************************************
*******************************************************************************
*******************************************************************************
***********]. Examples of the respective percentages are outlined in Attachment
 6.1(b). Reasonable out-of-pocket expenses incurred in obtaining such licensee
 shall be shared equally by the Parties. Notwithstanding the above, either
 Party may receive, without sharing with the other Party, reimbursement from
such licensee for reasonable,[*************************************************
*********************] costs of research, development and/or marketing costs
(whether internal or Third Party) to be incurred by such Party for work to be
conducted in the future on behalf of the licensee.

                                       36
<PAGE>
Any amounts in excess of such reimbursement shall be shared in the same
proportion as calculated above in this Section 6.1(b) All amounts from licensees
received by either Party shall be fully disclosed to the other Party and subject
to audit (including without limitation the calculation of Fully-Loaded costs)
pursuant to Section 6.5.

      (c) If the Proceeding Party elects to distribute or sublicense a
Development or Marketed Compound in any country, and a license must be obtained
from a Third Party to manufacture and/or market such Development or Marketed
Compound to avoid a non-frivolous claim of patent infringement, the Proceeding
Party shall offset the following portion of the Third Party license fee, royalty
or other similar payments ("Licensee Fees") against the Opting Out Party's
royalty:

<TABLE>
<CAPTION>
                                     Percent of Licensee Fee Offset
[******************************]     Against the Opting Out Party's Royalty
--------------------------------     --------------------------------------
<S>                                  <C>
        [****]                               [******]
        [****]                               [******]
        [****]                               [******]
        [****]                               [******]
</TABLE>

      Any portion of Licensee Fees paid by the Proceeding Party that is to be
offset against the Opting Out Party's royalty but that exceeds the Opting Out
Party's royalty payable, shall be carried forward and accrue interest pursuant
to Section 6.4 and be offset against future royalties as such royalties become
payable.

      6.2.  ROYALTY PAYMENT.

      (a) Royalties payable under Sections 2.4(e) and 6.1 will be paid not later
than sixty (60) calendar days following the end of each Fiscal Quarter. All
payments shall be accompanied by a report in writing showing the Fiscal Quarter
for which such payment applies, the amount billed to Third Parties for Marketed
Compounds sold during such Fiscal Quarter, the deductions from the amount billed
to arrive at the Net Sales, the Net Sales for the Fiscal Quarter, and the
royalties due on such Net Sales, such report being broken down by Marketed
Compound and country. All royalties will be paid in the currency where Net Sales
take place or, at the option of the payee, in US dollars at a rate of exchange
on the last business day of the Fiscal Quarter as quoted in The Wall Street
Journal (or Citibank, N.A. if such rates are not available in The Wall Street
Journal).

      (b) All royalties due under this Article VI will be deposited in a bank
chosen by the recipient by the date due. Any amounts or royalties prohibited
from export by a
                                       37
<PAGE>
particular country will be deposited in a bank chosen by the recipient in
such country. Any deductions for withholding taxes imposed by the country in
which Net Sales take place will be withheld and paid as required by law. The
amount of tax withheld shall be for the account of the Party receiving the
payment. The amount of withholding tax will be allocated, if applicable, in the
ratio of the respective income to which the withholding tax is related. The
paying Party will provide promptly upon request any receipts from the
governmental or taxing authority evidencing payment of such taxes and will
assist the receiving Party in claiming relief from double taxation.

      6.3. RECORDS. Procter & Gamble and Regeneron will maintain, and will
require their Affiliates and sublicensees to maintain, complete and accurate
records of Net Sales of Marketed Compounds sold subject to the royalty
provisions of Sections 2.4(e) and 6.1 and the audit provisions of Section 6.5.

      6.4. INTEREST RATE. Unless otherwise provided in this Agreement, any
payments past due will bear interest at the prime rate (such quoted in The Wall
Street Journal on the first day of the month of the accrual) plus two (2)
percentage points, compounded monthly.

      6.5. AUDIT. Records shall be open for audit during reasonable business
hours for a period of three (3) years from creation of individual records for
examination not more often than once each year by an independent certified
public accountant ("CPA") selected by the payee and reasonably acceptable to the
payer for the sole purpose of verifying the correctness of payments to be made
under this Agreement. If the CPA finds a discrepancy of greater than ten (10)
percent of such payment, the CPA shall submit a detailed report regarding the
audit and such discrepancy to both Parties within thirty (30) days of commencing
the audit. The Parties shall attempt to resolve such discrepancy to their mutual
satisfaction during the next fifteen (15) days. If the Parties cannot resolve
the discrepancy, their CEOs shall meet within ten (10) days after such fifteen
(15) day time period. If the CEOs cannot resolve the dispute within five (5)
days, either Party may take such dispute to arbitration pursuant to Section
11.4. The calculation of such payment shall be deemed final (and not subject to
audit or dispute resolution) five (5) years after the period in which such
payment was due, unless arbitration pursuant to Section 11.4 is commenced prior
to such time. Out-of-pocket expenses incurred with respect to such CPA shall be
paid by the payee; however, the payer shall reimburse the payee for such CPA
expenses if the discrepancy is greater than ten (10%) percent, as such
discrepancy is determined by the CEOs or arbitrators.

                                       38
<PAGE>

                 ARTICLE VII - PATENTS AND INFRINGEMENT

      7.1. DISCLOSURE. Procter & Gamble will promptly disclose to Regeneron all
Procter & Gamble Technology described in Section 1.43. Regeneron will promptly
disclose to Procter & Gamble all Regeneron Technology described in Section 1.47
The Parties intend that there be a timely and full exchange of all information
arising from each Research Collaboration Plan or Product Plan subject to the
terms and conditions of this Agreement. Each Party shall promptly disclose to
the other Party any critical data or development which it reasonably believes
would or could have a material effect, whether positive or negative, on a
Research Collaboration Plan or Product Plan.

      7.2. PATENT APPLICATIONS. Regeneron and Procter & Gamble will discuss and
evaluate Technology disclosed pursuant to Section 7.1, and confer regarding the
advisability of filing patent applications to cover any Technology. The Party
(herein "Responsible Party") responsible for the filing, prosecution and
maintenance of patent applications shall be: (a) Procter & Gamble, if the
subject invention is made solely by employees of Procter & Gamble; (b)
Regeneron, if the subject invention is made solely by employees of Regeneron; or
(c) determined by agreement of the Parties for all other inventions, taking into
account the nature of the invention and the relationship of the invention to
inventions claimed in other patents or applications. Regeneron and Procter &
Gamble will discuss with each other the advisability of filing Patent
applications beyond the priority country.

     7.3. FILING AND PROSECUTION OF PATENTS. The Responsible Party shall, at its
expense, diligently file, prosecute, issue, and maintain patent applications
according to its own internal standards and for effectively covering other
inventions made by its employees or consultants. The Responsible Party will
endeavor to ensure that all patent applications are filed before any public
disclosures so as to ensure validity of patent applications filed outside of the
United States. The Responsible Party will submit a substantially complete draft
of each patent application to the other Party at least thirty (30) days prior to
the contemplated filing date and consider any comments of the other Party,
provided that in those circumstances where the Responsible Party believes time
is of the essence, the Responsible Party will endeavor to provide the other with
such advance notice as it reasonably can under the circumstances. Regeneron and
Procter & Gamble will confer with each other regarding the prosecution of such
Patent Applications and will copy each other with any official action and
submission in such Patent Applications.

                                       39
<PAGE>

      7.4. ALTERNATE RESPONSIBILITY FOR PROSECUTION. In the event the
Responsible Party determines that it will not file, prosecute, issue or
maintain, a Patent in a particular country, it shall promptly notify the other
Party. The other Party shall then have the right, but not obligation to assume
responsibility for the Patent in such country, and thereby become the
Responsible Party for that Patent in such country pursuant to Section 7.3. The
other Party shall be given all necessary authority by the original Responsible
Party to file, prosecute, issue, and maintain the Patent in such country.

      7.5.  INFRINGEMENT.  Procter & Gamble and Regeneron shall
promptly notify the other in writing of any infringement of a Patent
licensed or to be licensed pursuant to Article V of which they become
aware.

      7.6. ENFORCEMENT OF PATENTS. Regeneron and Procter & Gamble may, but shall
not be required to, prosecute any alleged infringement or threatened
infringement of a Patent licensed or to be licensed pursuant to Article V of
which they are aware or which is brought to their attention. The prosecuting
Party shall act in its own name and at its own expense unless the other Party at
its option pays fifty percent (50%) of all reasonable out-of-pocket costs prior
to the commencement of trial or an agreement on a settlement. Regeneron and
Procter & Gamble shall cooperate fully with each other including, if required to
bring such action, the furnishing of power of attorney. Any recovery obtained
shall belong to the prosecuting Party unless the other Party has paid fifty
percent (50%) of said costs in which case each Party will receive fifty percent
(50%) of any recovery.

      7.7. ALTERNATE RESPONSIBILITY FOR ENFORCEMENT. If Regeneron or Procter &
Gamble has failed to prosecute under Section 7.6 with respect to alleged or
threatened infringement of one of its Patents (i) three (3) months after it has
been notified in writing by the other of such alleged infringement or (ii) one
(1) month before the time limit, if any, set forth in the appropriate laws and
regulations for the filing of such actions, whichever comes first, the other
may, but shall not be required to, prosecute any alleged infringement or
threatened infringement of the Patent. Such prosecuting Party shall act in its
own name and at its own expense. In such event, both Parties shall cooperate
fully with each other at their own expense, including if required in order to
bring such an action, the furnishing of a power of attorney. Any recovery
obtained shall belong to the prosecuting Party.

     7.8. TRADEMARK INFRINGEMENT AND ENFORCEMENT. Procter & Gamble and Regeneron
shall promptly notify the other in writing of any infringement of a trademark

                                       40
<PAGE>
under Section 4.5 of which they become aware. The owner of the trademark
application or registration may, but shall not be required to, prosecute any
such alleged infringement or threatened infringement. The prosecuting Party
shall act in its own name (unless joinder of the other Party is required by law
in which case it shall be joined) and at its own expense unless the other Party
at its option pays fifty percent (50%) of all reasonable out-of-pocket costs
prior to the commencement of trial or an agreement on a settlement. Regeneron
and Procter & Gamble shall cooperate fully with each other in such action. Any
recovery obtained shall belong to the prosecuting Party unless the other Party
has paid fifty percent (50%) of the costs in which case each Party will receive
fifty percent (50%) of any recovery.

     7.9. ALTERNATE RESPONSIBILITY FOR TRADEMARK ENFORCEMENT. If the owner of
the trademark application or registration has failed to prosecute under Section
7.8 with respect to an alleged or threatened infringement of a trademark (i)
three (3) months after it has been notified in writing by the other of such
alleged infringement or (ii) one (1) month before the time limit, if any, set
forth in the appropriate laws and regulations for the filing of such actions,
whichever comes first, the other Party may, but shall not be required to,
prosecute any alleged infringement or threatened infringement of the trademark.
Such prosecuting Party shall act in its own name and at its own expense. In such
event, both Parties shall cooperate fully with each other at their own expense.
Any recovery obtained shall belong to the prosecuting Party.

                         ARTICLE VIII - CONFIDENTIALITY

      8.1.  CONFIDENTIALITY AND NON-USE OBLIGATIONS.  Each Party shall
maintain in confidence all information (herein "Information") which is:

            (a)  disclosed to it by the other Party pursuant to Section 7.1;

            (b)  developed by the Party during the Research Term; or

            (c)  other information ("Other Information") disclosed by
      the other Party which is not within the scope of the collaboration and
      which is considered confidential by the other Party, and so designated as
      confidential in writing when first disclosed or within thirty (30) days
      after disclosure if the first disclosure is oral.

      The Party shall take all reasonable precautions to:

            (d)   prevent disclosure of such Information to Third
      Parties, except as set forth in Section 2.9, Section 8.3 and Section
      11.10, or as may be necessary for the filing or prosecution of patent
      applications pursuant to Article VII;

                                       41
<PAGE>

            (e)  use Know-how pursuant to the rights and obligations of
      the Party pursuant to Article V; and

            (f)  use Other Information only for the purposes of this
      Agreement.

      These restrictions upon disclosure and use of Information shall
terminate ten (10) years after the date such Information is developed or
disclosed as set forth above, but shall not apply to any specific portion of
Information which:

                  (i)  is Other Information already in the possession of
            a Party at the time of disclosure by the other Party;

                  (ii) is or later becomes available to the public other
            than by default by the Party;

                  (iii) is received from a Third Party having no
            obligation of confidentiality to the other Party;

                  (iv) is Other Information developed by the Party
            entirely without reference or use of Information, as
            established by probative documentary evidence; or

                  (v)  is required to be disclosed by law or government
            regulation.

      8.2. PRIOR CONFIDENTIALITY AGREEMENTS. All Information that is covered
under the confidentiality and non-use obligations of Section 8.1. of the
Multi-Project Collaboration Agreement (hereinafter referred to as "MPC
Information") applicable to this Agreement that was to be kept confidential
under the Multi-Project Collaboration Agreement as of the Effective Date will be
subject to the terms of Section 8.1 as if disclosed under this Agreement. All
other MPC Information shall be treated as set forth in this Section 8.2. The
confidentiality and non-use obligations set forth in Section 8.1 of the
Multi-Project Collaboration Agreement shall survive for each Party pursuant to
the terms of Section 11.8 thereof (i) for Regeneron with respect to any MPC
Information relating to Procter & Gamble Retained Projects, (ii) for Procter &
Gamble with respect to any MPC Information relating to Regeneron Retained
Projects, and (iii) for both Parties with respect to all other MPC Information
unrelated to any of the Retained Projects of the Field. Notwithstanding the
terms of Section 11.8 of the Multi-Project Collaboration Agreement, all
confidentiality and non-use obligation set forth in Section 8.1 of the
Multi-Project Collaboration Agreement relating to any Mutual Retained Project
shall no longer remain in effect.

      8.3. RESEARCH MANUSCRIPTS AND ABSTRACTS. It is understood the Parties may
wish to publish or otherwise disclose technology to a Third Party for
publication in a

                                       42
<PAGE>
reputable scientific forum (for example, as an abstract, poster presentation,
lecture, article, book, or any other means of dissemination to the public).
Either Party may make such a disclosure to a Third Party regarding preclinical
research solely invented by its own employees, provided that if appropriate, a
patent application adequately describing and claiming any technology embodied in
such disclosure has been filed pursuant to Article VII. If such disclosure is
related to clinical research or work jointly invented by the Parties, no such
disclosure will be made to a Third Party until a patent application has been
filed adequately describing and claiming any patentable technology embodied in
such disclosure pursuant to Article VII and the non-disclosing Party has been
provided thirty (30) days to review and comment on such disclosure. Such
disclosures may be made to a Third Party regarding clinical research only if
clinical data has been locked and if disclosure presents no significant risk to
regulatory filings and serves a compelling business reason for publication. Any
disputes regarding the appropriateness and content of any such disclosure shall
be resolved by the PC.

      8.4. THIRD PARTY ACCESS TO DEVELOPMENT COMPOUNDS. The Parties recognize
that inappropriate use of a Development Compound outside the scope of the
approved Product Plan may result in Adverse Experiences that could adversely
affect the labeling of the Compound or the ability of the Parties to gain
regulatory approval to market the Compound. Therefore, neither Party shall
provide a Development Compound in any form to a Third Party without the prior
written consent of the other Party. Upon receiving notice that the other Party
intends to provide a Development Compound to a Third Party, a Party shall have
two (2) weeks to provide or withhold consent. Before providing a Development
Compound to a Third Party, the Parties shall enter into a written agreement with
such Third Party obligating the Third Party to disclose to the Parties all
results of research involving the Development Compound, including without
limitation all Adverse Experiences.

      8.5. PUBLICATIONS. The Parties recognize that independent investigators
will be engaged to conduct pre-clinical and clinical trials of Development
Compounds, and that the disclosure of information regarding such trials could be
detrimental to the ability of the Parties to effectively develop and market such
Compound. To the extent practicable, the Parties will enter into agreements with
investigators that require the approval of the Parties before the publication of
information concerning a Development Compound.

      8.6. SUMITOMO COMPOUNDS. Notwithstanding anything to the contrary, nothing
in this Article VIII shall govern the Sumitomo Compounds.

                                       43
<PAGE>

          ARTICLE IX - REPRESENTATIONS, WARRANTIES AND INDEMNIFICATION

      9.1.  PATENTS.

            (a) Each Party warrants that, as of the Effective Date, it has no
actual knowledge of any information rendering invalid or unenforceable any
Patent licensed to the other Party under Article V or VII. Each Party will
promptly inform the other Party immediately if it obtains such information after
the Effective Date.

            (b) Each Party warrants that it is has no actual knowledge of any
patents or Know-how owned by a Third Party that might prevent, inhibit, or limit
the Parties from conducting the research, development and marketing activities
under this Agreement other than what has been previously disclosed. Each Party
warrants that, except as disclosed in Attachment 9.1(b), it has not entered into
any agreement with a Third Party that might prevent, inhibit, or limit the
Parties from conducting the research, development and marketing activities under
this Agreement.

      9.2. NO GUARANTEE. The Parties understand that the research and
development work to be conducted pursuant to this Agreement will involve
untested, experimental, and currently undeveloped technology and that neither
Regeneron nor Procter & Gamble guarantees the safety or usefulness of any
Compound. Except as expressly set forth in this Agreement, the Parties disclaim
all warranties of any nature, express or implied.

      9.3.  INDEMNIFICATION.

            (a) Indemnification Regarding Joint Activities, General. Any and all
liability, damage, loss, cost (including without limitation reasonable
attorneys' fees) and expense resulting from any suits, claims, actions, demands,
liabilities, expenses and/or loss ("Losses") relating to the joint development,
manufacture, use, storage, distribution or sale of any Compound ("Joint
Activities") will be shared equally. Each Party shall indemnify and hold
harmless the other Party for such Party's respective share of such liability;
provided, however, that the portion of Losses due to the gross negligence or
willful or intentional misconduct of either or both Party(ies) shall be governed
by Section 9.3(b).

            (b) Indemnification by the Parties. Each Party shall indemnify and
hold the other Party harmless from and against that portion of any and all
Losses due to the gross negligence or willful or intentional misconduct of such
indemnifying Party, as well as any Losses caused by the negligence or misconduct
of the other Party that were not caused by Joint Activities.

                                       44
<PAGE>

            (c) Indemnification by the Proceeding Party. The Proceeding Party
agrees to save, defend and hold the Opting Out Party harmless from and against
any and all Losses to the extent that such factual allegations forming the
primary basis for such Losses occurred after the Party became an Opting Out
Party with respect to that Compound and/or country. Both Parties shall provide
prompt notice to the other of such potential Losses. The Proceeding Party shall
assume control of the defense of the potential Losses (including without
limitation the right to settle the claim). The Opting Out Party shall provide
reasonable cooperation to the Proceeding Party, and the Proceeding Party shall
reimburse the Opting Out Party its reasonable out-of-pocket expenses.

            (d) Indemnification Procedure. In the event that either Party
receives notice of potential Losses, such Party shall immediately inform the
other Party and the OC. The OC shall decide the manner in which to respond to
and handle the claim. If the OC cannot decide on how to respond to the claim
prior to five (5) days before the answer is due, the Party receiving the notice
shall answer the claim and take reasonably necessary actions to defend itself,
and the other Party may appoint its own counsel at its own expense, until the OC
agrees on how to handle the claim.

                ARTICLE X - TERM, TERMINATION; CHANGE OF CONTROL

      10.1. EFFECTIVE DATE AND TERM.

            (a)  Effective Date.  This Agreement shall become effective
on January 1, 2001  ("Effective Date").

            (b) Term. Unless terminated earlier by mutual agreement or by either
Party pursuant to Section 10.3 and subject to Section 3.2(c) (in which case
relevant portions of this Agreement may come back into effect for any Lead
Compound discovered during the Tail Period), this Agreement shall commence on
the Effective Date and expire at the later of (i) the end of the Research Term;
(ii) the end of development and marketing of the last Compound to be developed
or marketed pursuant to this Agreement (unless such Compound is the subject of a
separate agreement); or (iii) the end of the Royalty Term. Rights in technology
upon termination shall be as set forth in Section 5.3.

      10.3. DEFAULT. Failure by either Party (the "Defaulting Party") to comply
with any of the material obligations contained in this Agreement, or any of the
Securities Agreements, the Registration Rights Agreement, the Warrants Purchase
Agreement or any J-V Agreement shall entitle the other Party (the "Nondefaulting
Party") to give to the Defaulting Party notice specifying the nature of the
default and requiring it to cure such default. If the Defaulting Party disagrees
with the existence, extent or nature of the

                                       45
<PAGE>
default, the Parties shall use good faith efforts to resolve the dispute within
thirty (30) days. If (i) such default is not cured with such thirty (30) day
period after the receipt of such notice or (ii) the Parties have not otherwise
resolved the dispute during such thirty (30) day period, the Nondefaulting Party
shall be entitled to initiate arbitration under Section 11.4 and at its sole
discretion terminate this Agreement. In the event of such termination, and in
addition to any other remedies available to the Nondefaulting Party, the
Defaulting Party shall be deemed an Opting Out Party with respect to any
Compounds pursuant to Section 5.5.

      10.4. CHANGE OF CONTROL.

            (a) In the event of a Change in Control, as that term is defined in
Section 10.6(a), of either the Parties or their respective Affiliates that have
responsibilities or obligations under this Agreement (each collectively or
individually then referred to as the "Acquired Company") and the Acquired
Company is not an Opting Out Party with respect to all Compounds in all
countries under this Agreement, then the Party affiliated with the Acquired
Company shall notify the other Party of any such Change in Control as soon as
the Change in Control may publicly be announced. Upon receipt of any such
notification, the other Party or an Affiliate thereof (the "Electing Company")
shall have the unilateral right to give notice to the Acquired Company within
thirty (30) days after its next regularly scheduled board meeting, but in no
event longer than sixty (60) days, after receipt of the Acquired Company's
notification that the Electing Company:

                       (i) elects not to continue the research, development and
            marketing collaboration, whether or not a J-V has been formed (the
            "Option"), in which case a determination of the License Fee pursuant
            to Section 10.7 will be made, and within [**********] following such
            License Fee determination will make the further election either to
            purchase the entire interest of the Party affiliated with the
            Acquired Company under this Agreement or any J-V Agreement
            ("Acquired Company Interest") or offer the Acquired Company the
            option to purchase the entire interest of the Electing Company under
            this Agreement or any J-V Agreement ("Electing Company Interest") at
            the License Fee (but in the event that the Acquired Company does not
            desire to purchase the Electing Company Interest, the interests of
            the Parties shall be disposed of by sale, license or other
            commercially reasonable arrangement for a price that maximizes value
            for both Parties, paid by a Third Party or a Party, and each Party
            shall have the right to receive half of the consideration thus
            obtained), or

                                       46
<PAGE>

                       (ii) desires to continue the collaboration for a period
            of up to [**********] from the date of the Change in Control (the
            "Trial Period") upon the express condition that the ultimate parent
            of the entity acquiring control of the Acquired Company within
            [**********] thereafter agrees in writing to such Trial Period and
            otherwise agrees to be bound by the provisions of this Agreement,
            the Registration Rights Agreement, the Securities Agreements, and
            any J-V Agreement. If the ultimate parent of the acquiring entity
            accepts these conditions, the collaboration shall continue, and the
            Option shall expire unless the Electing Company exercises the Option
            within [***********] days prior to the expiration of the Trial
            Period. If the ultimate parent of the acquiring entity fails to give
            notice within the required period that it will be bound by the
            provisions of such aforementioned Agreements, the Electing Company
            shall be deemed to have exercised the Option as of the expiration of
            such [**********] period and the Parties shall then follow the
            procedures set forth in this Section 10.4.

       10.5. SUBSTANTIAL STOCK ACCUMULATION. In the event of a Substantial Stock
Accumulation in either the Procter & Gamble Parent or the Regeneron Parent, as
soon as the Party affiliated with the Affected Company has knowledge of the
Substantial Stock Accumulation, it shall give prompt notice to the other Party.
Such notice shall be separate from and in addition to the notice provided for in
Section 10.4 and must be given regardless of whether the Party affiliated with
the Affected Company regards the Substantial Stock Accumulation as being not in
the best interest of the collaboration. From the date on which the Party
affiliated with the Affected Company has notice of the Substantial Stock
Accumulation, the following provisions shall become effective and remain
effective until the Substantial Stock Accumulation is eliminated, unless
otherwise agreed:

                  (i) If the Party that is not affiliated with the Affected
            Company reasonably determines in good faith that the person or
            entity making the Substantial Stock Accumulation is a competitor of
            such Party or its Affiliates, such Party may so inform the other
            Party in writing. Promptly after receipt of such notice, the Party
            affiliated with the Affected Company shall establish a procedure
            whereby no director or executive employee of the Affected Company
            who was not a director or employee of the Affected Company prior to
            the Substantial Stock Accumulation, and who was previously a
            director or employee of the person or entity making the

                                       47
<PAGE>
            Substantial Stock Accumulation (a "Tainted Director or Executive"),
            shall receive any of the following: (x) confidential information of
            the other Party and its Affiliates; and (y) confidential information
            of the collaboration, except that any such Tainted Director or
            Executive can be given information as to actual and projected sales
            and profits of the collaboration.

                  (ii) If the Party that is not affiliated with the Affected
            Company does not give notice pursuant to this Section 10.5, the
            Party affiliated with the Affected Company shall establish a
            procedure whereby no Tainted Director or Executive shall receive
            confidential information of the other Party and its Affiliates but
            need not place any restrictions on confidential or other information
            of the collaboration.

                  (iii) In the event of a material violation of this Section
            10.5, the non-breaching Party may, without resort to the dispute
            resolution procedure set forth in Articles II and XI, bring an
            immediate court action or enjoin such violation and to recover any
            damages that it may have incurred by reasons of such violation.

      10.6. DEFINITIONS.

            (a) For purposes of this Agreement, a "Change in Control" of a
company shall be deemed to have occurred in the event of (i) a merger,
consolidation, reorganization, recapitalization, the purchase of substantially
all of the company's assets, or other transaction in which or as result of which
the common stock of the company, or a successor entity having the same ownership
as the company, shall cease (except temporarily) to be a publicly traded
security; or (ii) the acquisition by any individual, firm, corporation, or
entity (other than any profit sharing or other employee benefit plan of the
company or any Affiliate, or any employee or group of employees or former
officers an/or directors of the company or its Affiliates) of beneficial
ownership, directly or indirectly, of securities of the company representing
more than [**************] of the combined voting power of the company's then
outstanding voting securities. Notwithstanding the foregoing, for purposes of
this Section 10.6(a), a Change in Control shall only be deemed to occur for
Procter & Gamble if there is a Change in Control of The Procter & Gamble Company
or Procter & Gamble Pharmaceuticals, Inc.

            (b) A "Substantial Stock Accumulation" of a company shall be deemed
to have occurred in the event of the accumulation by any individual, firm,
corporation, or entity (other than any profit sharing or other employee benefit
plan of the company or any Affiliate, or any employee or group of employees or
former officers and/or directors of the company or its Affiliates) of beneficial
ownership, directly or

                                       48
<PAGE>
indirectly, of securities of the company representing more than
[*****************] of the combined voting power of the company's then
outstanding voting securities.

                 (c) Notwithstanding the foregoing in Sections 10.6(a) and (b),
Leonard Schleifer, M.D., Ph.D., the present President and Chief Executive
Officer of Regeneron, may increase his percentage of Regeneron's or Regeneron's
Parent's combined voting power of its outstanding securities and no Substantial
Stock Accumulation or Change in Control for Regeneron shall be deemed to have
occurred. For the purposes of this Section 10.6(c), Dr. Schleifer's ownership of
securities of Regeneron or Regeneron's Parent shall be deemed to be his direct
or indirect ownership of capital shares or options to purchase such capital
shares of Regeneron or Regeneron's Parent and the direct or indirect ownership
of such shares by members of his family living in his household to the extent
that Dr. Schleifer retains voting control, the power to exercise such options,
and the right to dispose of such shares, and shall not include any other shares
over which he does not possess Beneficial Ownership, as defined in the
Securities and Exchange Act of 1934, as amended.

                 10.7. LICENSE FEE.  The "License Fee" for purposes of Sections
10.4 and  10.5 shall be determined as follows:

                 (a) License Fee has two components: a Valuation (as defined
herein) of the Parties' interest in the Agreement or J-V Agreement with respect
to Compounds to which neither Party has Opted Out in total and a running royalty
on Net Sales of any Compound for which neither Party has Opted Out, such rate
and term being calculated as per Section 6.1 ("Running Royalty"). Each Party
shall designate an investment banking firm of its choice, and each investment
banking firm will be asked to prepare an appraisal as to the fair market value
of the collaboration as a going concern that would be received in cash from a
Third Party if a sale of the collaboration were made to a Third Party, taking
into account any contractual obligation of either Party or its Affiliates to
refrain from manufacturing or marketing a product competitive with the products
in the Territory for any period, the value of the information, Patents and
Know-how, and other assets being licensed and the potential market for such
Compounds in the Territory ("Fair Market Value"). The Fair Market Value shall
not include Compounds in specific countries or in the entire Territory for which
either Party is an Opting Out Party, as such royalty shall continue to be
governed pursuant to Section 6.1, regardless of a Change of Control.
[*****************************************************************************
*******************************************************************The
investment bankers will be asked to submit their Valuations within thirty (30)
days after the Purchase Date as defined in Section 10.7(e). In the event of a
Party's failure to

                                       49
<PAGE>
obtain an investment banking firm's Valuation within thirty (30) days after the
Purchase Date, the Valuation will be the Valuation determined by the investment
banking firm appointed by the other Party. An example of the operation of the
License Fee is set forth in Attachment 10.7(a).

      (b) If the difference between the lower Valuation and the higher Valuation
is not more than [***********] of the higher Valuation, or if the Valuations are
equal, the final Valuation shall be the average of the Valuations. If the
difference between the [*********] Valuations is more than [**************] of
the higher Valuation, the investment bankers will select a third investment
banking firm from those known as major bracket investment banking firms, and
that firm shall also prepare a Valuation. The third investment banking firm will
not have access to the Valuations prepared by the other investment banking
firms. The [*************] Valuations that are the closest in value then shall
be averaged, and the resulting average shall be the final Valuation.

      (c) The purchase of the interest shall thereafter be consummated by
payment of the Valuation and the obligation to pay the Running Royalty within
sixty (60) days after receipt of all investment bankers' valuations or such
later date upon which all necessary regulatory approvals have been obtained
and/or regulatory waiting periods have expired.

      (d) The Party that sells its entire interest in the collaboration
("Seller") shall grant to the other Party ("Purchaser") an exclusive,
royalty-free license in the Territory under Seller's Patents and Seller's
Know-how to make, have made, use, import, offer for sale and sell Lead Compounds
and Validated Targets and a non-exclusive, royalty-free license in the Territory
under Seller's Patents and Seller's Know-how to make, have made, use, import,
offer for sale and sell other Seller's Technology. "Seller's Patents," "Seller's
Know-how" and "Seller's Technology" shall be Procter & Gamble or Regeneron
Technology, Patents and Know-how, depending upon which Party is Seller.

      (e) Each Party shall bear the expense of obtaining the Valuation of the
investment bankers selected by such Party, and if a third investment banker is
selected, the expense of obtaining its Valuation shall be borne equally by the
Parties.

      (f) Unless otherwise agreed in writing by the Parties, the License Fee for
a license under Sections 10.4, 10.5 and 10.6 shall be calculated as of the date
of the Electing Company's notice that it elects to exercise the Option under
Sections 10.4 or 10.5 or the Purchasing Company's notice that it desires to
license the interest of the Party affiliated with the Affected Company under
Section 10.4 (such date shall be referred to as the "Purchase Date").

      (g) During the pendency of the Option election and valuation process and
any time period when the Parties are attempting to sell their interest to a
Third Party pursuant

                                       50
<PAGE>
to Section 10.4(a)(i), the Parties shall continue to perform their customary
activities under this Agreement or any J-V Agreement.

      (h) Seller and Purchaser shall cooperate with each other in good faith to
facilitate the transfer of the Seller's interest in the collaboration, including
transferring Information relating to the collaboration to Purchaser, so as to
minimize disruption to the business. As used in this Section, "Information"
means any confidential information and trade secrets, including but not limited
to information relating to inventions, disclosures, processes, systems,
Know-how, methods, techniques, formulations, drawings, patents, patent
applications, sales and marketing information, materials, services, research and
development activities and plans, clinical studies, manufacturing information
and regulatory filings.

                           ARTICLE XI - MISCELLANEOUS

      11.1. FORCE MAJEURE. Neither Party shall lose any rights hereunder or be
liable to the other Party for damages or loss on account of failure of
performance by the Defaulting Party if the failure is occasioned by government
action, war, fire, explosion, flood, strike, lockout, embargo, act of God, or
any other similar cause beyond the reasonable control of the Defaulting Party,
provided that the Party claiming force majeure has exerted all reasonable
efforts to avoid or remedy such force majeure and given prompt notice to the
other Party.

      11.2. NOTICES. Any notices or communications provided for in this
Agreement to be made by either of the Parties to the other shall be in writing,
in English, and shall be made by prepaid air mail with return receipt addressed
to the other at its address set forth above. Any such notice or communication
may also be given by hand or facsimile to the appropriate designation with
confirmation of receipt. Either Party may by like notice specify an address to
which notices and communications shall thereafter be sent. Notices sent by mail
shall be effective upon receipt; notices given by hand shall be effective when
delivered.

            Notices for Regeneron shall be sent to:

                         Regeneron Pharmaceuticals, Inc.
                         Attn:  Corporate Secretary
                         777 Old Saw Mill River Road
                         Tarrytown, New York 10591-6707

                                       51
<PAGE>

            With copy to:

                         Regeneron Pharmaceuticals, Inc.
                         Attn:  General Counsel
                         777 Old Saw Mill River Road
                         Tarrytown, New York 10591-6707

            Notices for Procter & Gamble shall be sent to:

                         Procter & Gamble Pharmaceuticals, Inc.
                         Attn:  President
                         Health Care Research Center
                         8700 Mason-Montgomery Road
                         Mason, OH  45040

            With copy to:

                         Procter & Gamble Pharmaceuticals, Inc.
                         Attn:  Associate General Counsel-Patents
                         Health Care Research Center
                         8700 Mason-Montgomery Road
                         Mason, Ohio 45040

      11.3. GOVERNING LAW. This Agreement shall be governed by the laws of the
State of Delaware, as such laws are applied to contracts entered into and to be
performed within such state. Any claim or controversy arising out of or related
to this Agreement or any breach hereof shall be submitted to arbitration
pursuant to Section 11.4. The United Nations Convention on Contracts for the
International Sale of Goods will not apply to this Agreement.

      11.4. ARBITRATION. Subject to Sections 2.8 and 10.5, disagreements under
this Agreement shall be settled by arbitration in accordance with the commercial
arbitration rules of the American Arbitration Association. The parties further
agree that each such disagreement be submitted to a panel of three (3) impartial
arbitrators with each Party selecting one (1) arbitrator within fifteen (15)
days of a request for arbitration and the two (2) selected arbitrators selecting
a third arbitrator who is experienced in the United States pharmaceutical
industry within thirty (30) days after the request. Any arbitration hereunder
shall commence within thirty (30) days after appointment of the third arbitrator
and shall be held in Boston, Mass., U.S.A. Upon reasonable notice and prior to
any hearing, the Parties will allow document discovery and will disclose all
materials relevant

                                       52
<PAGE>
to the subject matter of the dispute. The arbitrators shall make final
determinations as to any discovery disputes. The decision of the arbitrators
shall be rendered no later than sixty (60) days after commencement of
arbitration. The costs of arbitration shall be split by the parties unless the
arbitrators decide otherwise. Any judgment or decision rendered by the panel
shall be binding upon the Parties and shall be enforceable by any court of
competent jurisdiction.

      11.5. NON-WAIVER OF RIGHTS. Except as specifically provided for herein,
the waiver from time to time by any of the parties of any of their rights or
their failure to exercise any remedy shall not operate or be construed as a
continuing waiver of same or of any other of such Party's rights or remedies
provided in this Agreement.

      11.6. SEVERABILITY. If any term, covenant, or condition of this Agreement
or the application thereof to any Party or circumstance shall, to any extent, be
held to be invalid or unenforceable, then (i) the remainder of this Agreement,
or the application of such term, covenant or condition to Parties or
circumstances other than those as to which it is held invalid or unenforceable,
shall not be affected thereby and each term, covenant, or condition of this
Agreement shall be valid and be enforced to the fullest extent permitted by law
and (ii) the Parties hereto covenant and agree to renegotiate any such term,
covenant, or application thereof in good faith in order to provide a reasonably
acceptable alternative to the term, covenant, or condition of this Agreement or
the application thereof that is invalid or unenforceable, and in the event that
the Parties are unable to agree upon a reasonably acceptable alternative, then
the Parties agree that a submission to arbitration shall be made in accordance
with Section 11.4 to establish an alternative to such invalid or unenforceable
term, covenant, or condition of this Agreement or the application thereof, it
being the intent that the basic purposes of this Agreement are to be
effectuated.

      11.7. ENTIRE AGREEMENT. This Agreement sets forth all the covenants,
promises, agreements, warranties, representations, conditions, and
understandings between the Parties hereto in the scope of the Collaboration ,
with the exception of any agreements by the Parties executed at an even date
hereof, and supersedes and terminates all prior agreements and understanding
between the parties under this Agreement. No subsequent alteration, amendment,
change, or addition to this Agreement shall be binding upon the Parties hereto
unless reduced to writing and signed by the respective authorized officers of
the Parties.

                                       53
<PAGE>

      11.8. SURVIVAL. Sections 2.2, 2.10, 5.3, 5.4, 8.1, and 8.2 shall survive
the termination of this Agreement to the extent specified therein. Section 9.3
and any accrued obligations under this Agreement shall survive termination of
this Agreement without limit as to time.

      11.9. ASSIGNMENT.

            (a) Procter & Gamble and Regeneron may assign any of their rights or
obligations under this Agreement in any country of the Territory to any
Affiliates; provided, however, that such assignment shall not relieve the
assigning Party of its responsibility for performance of its obligations under
this Agreement.

            (b) The Parties recognize that each may perform some of its
obligations hereunder through Affiliates; provided, however, that Procter &
Gamble and Regeneron shall remain responsible and be guarantors of such
performance by their Affiliates and shall cause their Affiliates to comply with
the provisions of this Agreement in connection with such performance.

            (c) Procter & Gamble and Regeneron may only assign their rights
under this Agreement in any country of the Territory to a Third Party with
written permission of the other Party, which permission will only be given at
its sole discretion.

      11.10.      PUBLICITY.

            (a) Procter & Gamble and Regeneron will jointly discuss, based on
the principles of Section 11.10(b), any press releases and any other public
statements regarding the execution and the subject matter of this Agreement, the
research to be conducted under this Agreement or any other aspect of this
Agreement, subject in each case to disclosure otherwise required by law or
regulation.

            (b) In the discussion and agreement of Section 11.10(a), the
principles observed by Procter & Gamble and Regeneron will be accuracy, the
requirements for confidentiality under Article VIII, the advantage a competitor
of Procter & Gamble or Regeneron may gain from any statement under Section
11.10(a), the requirements of disclosure under any securities laws or
regulations of the United States, including those associated with SEC and
regulatory filings and public offerings, the restrictions imposed by the Federal
Food, Drug and Cosmetic Act, and the standards and customs in the pharmaceutical
industry for such disclosures by companies comparable to Procter & Gamble and
Regeneron.

                                       54
<PAGE>

      11.11.      COUNTERPARTS.  This Agreement may be executed in one
or more counterparts, each of which shall be deemed an original, but
all of which together shall constitute one in the same instrument.

      11.12.      NO SOLICITATION.  During the Term of this Agreement,
the Parties shall not directly or indirectly solicit the other Party's
employees for employment or other consulting arrangements.

                             ARTICLE XII - EXECUTION

      12.1. In witness whereof the Parties have executed this Agreement in
duplicate originals by their proper officers as of the date and year first
written above.

The Procter & Gamble Company

By:
     -------------------------
      Mark Collar
      Vice President - Pharmaceuticals

Regeneron Pharmaceuticals, Inc.

By:
     -------------------------
      Leonard S. Schleifer, M.D., Ph.D.
      President and Chief Executive Officer

                                       55

<PAGE>
          ATTACHMENT 1.14(a) EXAMPLES OF REGENERON EXCLUDED TECHNOLOGY

[*******************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
********************************************************************************
***********************************************************************:
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
         *******************************
********************************************************************************
********************************************************************************
*******************************************************************************]

                                       56
<PAGE>
                  ATTACHMENT 1.21 REGENERON/P&GP GPCR PROGRAM

                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]
                                    [******]

                                       57
<PAGE>
    ATTACHMENT 2.2(c) MULTI-PROJECT COLLABORATION AGREEMENT PROJECT DIVISION

<TABLE>
<CAPTION>
            P&G                 MUTUAL                           REGENERON
 RETAINED PROJECTS         RETAINED PROJECTS                  RETAINED PROJECTS        JOINT PROJECTS
 -----------------         -----------------                  -----------------        --------------
<S>                  <C>                           <C>                                 <C>
[**************      [*************************     All other projects that are        GPCR Program***
**************]        *************************    not P&G Retained Projects,
                       *************************]   Mutually Retained
                                                    Projects and Joint Projects.
                                                   [************]

 [**************]    [*************************    [*******************************    Muscle
                      *****]                       [*******************************]

                                                   [*******************************
                                                   ********************************]   DDRs

                                                   [*******************************
                                                   ********************************
                                                   ********************************]

                                                   [**********]
                                                   [**********]
                                                   [**********]
                                                   [**********]
                                                   [**********]
                                                   [**********0

</TABLE>

* Ab = antibody based therapeutic, SM = small molecule based therapeutic

**Includes those GPCRs not identified in Attachment 1.21 and the Returned GPCRs,
if any.

***Includes the GPCRs identified in Attachment 1.21 with the exception
of the Returned GPCRs, if any.

                                       58
<PAGE>
                              ATTACHMENT 2.2(g)(i)
                             [********************]

<TABLE>
<CAPTION>
  PG       PG      PG      PG     PG       PG      PG     PG
 Number  Number  Number  Number  Number  Number  Number  Number
<S>      <C>     <C>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       59
<PAGE>
         [******************]

<TABLE>
<CAPTION>
     PG Number             PG Number             PG Number
     ---------             ---------             ---------
<S>                        <C>                   <C>
</TABLE>

                                       60
<PAGE>
[***************]

<TABLE>
<CAPTION>
           PG      PG      PG      PG      PG      PG      PG
         NUMBER  NUMBER  NUMBER  NUMBER  NUMBER  NUMBER  NUMBER
         ------  ------  ------  ------  ------  ------  ------
        <S>      <C>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       61
<PAGE>
                           [*****************************]

<TABLE>
<CAPTION>
          PG      PG       PG      PG      PG      PG     PG      PG
         Number  Number  Number  Number  Number  Number  Number  Number
         ------  ------  ------  ------  ------  ------  ------  ------
         <S>     <C>     <C>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       62
<PAGE>
                  [******************]

<TABLE>
<CAPTION>
          PG      PG       PG      PG      PG      PG
         Number  Number  Number  Number  Number  Number
         ------  ------  ------  ------  ------  ------
         <S>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       63
<PAGE>
                           [************]

<TABLE>
<CAPTION>
          PG      PG       PG      PG      PG      PG
         Number  Number  Number  Number  Number  Number
         ------  ------  ------  ------  ------  ------
         <S>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       64
<PAGE>
                               [****************]
<TABLE>
<CAPTION>
          PG      PG       PG      PG      PG      PG      PG
         Number  Number  Number  Number  Number  Number  Number
         ------  ------  ------  ------  ------  ------  ------
         <S>     <C>     <C>     <C>     <C>     <C>     <C>
</TABLE>

                                       65
<PAGE>
                                       66
<PAGE>
                              ATTACHMENT 2.2(g)(ii)

         [****************]
<TABLE>
<CAPTION>
          PG      PG       PG      PG
         Number  Number  Number  Number
         ------  ------  ------  ------
         <S>     <C>     <C>     <C>
</TABLE>

                                       67
<PAGE>
                                ATTACHMENT 2.5(a)
                   INITIAL MEMBERS OF THE OPERATING COMMITTEE

From Regeneron:

         [******************************]
         [******************************]

From Procter & Gamble:

         [******************************]
         [******************************]

                                       68
<PAGE>
                                ATTACHMENT 2.5(b)
                    INITIAL MEMBERS OF THE PROGRAM COMMITTEE

From Regeneron:

         [******************************].
         [******************************]
         [******************************]

From Procter & Gamble:

         [******************************]
         [******************************]
         [******************************]

                                       69
<PAGE>
                                ATTACHMENT 2.5(c)
                  INITIAL MEMBERS OF THE DEVELOPMENT COMMITTEE

From Regeneron:

         [******************************]

From Procter & Gamble:

         [******************************]

                                       70
<PAGE>
                                 ATTACHMENT 3.1
         TIMING AND CALCULATION OF RESEARCH AND/OR PRODUCT PLAN BUDGETS

BUDGET PROCESS

1)       [*****************]
         -   [****************************************************************
             *****************************************************************
         -   [****************************************************************]
         -   [****************************************************************]
         -   [****************************************************************]
         -   [****************************************************************]

2)       [*******************]
         -   [***************************************************************]
         -   [***************************************************************]
         -   [***************************************************************]
         -   [***************************************************************]

3)       [*******************]
         -   [***************************************************************].
         -   [***************************************************************]
         -   [***************************************************************]
         -   [***************************************************************]

       If a quarterly budget projection exceeds [*****] of the target quarterly
spending budget, the matter will be referred to the OC for approval /
non-approval of change in budget

                                       71
<PAGE>
                          ATTACHMENT 3.1 ("CONTINUED")

[************************]

[**************************]
          -     [**********************************************************]
                   [***************************************************]
          -     [*****************************]

                - [**********************************************************
                   *************************************************************
                   *************************************************************
                   -     [******************************************************
                   -     [******************************************************
                         -
                   [********************************************************
                         -
                   [********************************************************
                         -
                   [********************************************************
                         -
                   [********************************************************
                             -
                   [********************************************************

                   -     [****************************************************
                -  ************************************************************
                   *************************************************************
                -  *************************************************************

[***********************************************]
          -     [****************************************]
                -  [**************************************]
                -  [**************************************]
                -  [**************************************]
                -

                                       72
<PAGE>
                  ATTACHMENT 3.2 INFLATION PAYMENT ADJUSTMENT

[*********]

                           [****************** ******]
                           [****************** ******]
                           [****************** ******]

                [***********************************************]
                [***********************************************]

              [**************************************************]

[***************]

         [************************************************************]
         [************************************************************]

                                       76
<PAGE>
                              ATTACHMENT 3.2(b)(3)
              EXPENSES INCLUDED IN THE REGENERON RESEARCH FTE RATE

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]

-   [*************************************************************]
<PAGE>
                                 ATTACHMENT 3.3

[***************************]

-    [*************************************************************]
     [*************************************************************]

-    [*************************************************************]

-    [*************************************************************]

-    [*************************************************************]

     [*************************************************************]

-    [*************************************************************]

-    [*************************************************************]

-    [*************************************************************]

-    [*************************************************************]

-        [************************].

-        [******************].

-        [************************].

-        [************************].
<PAGE>
                                ATTACHMENT 6.1(b)
                 EACH PARTY'S SHARE OF ROYALTIES OR OTHER INCOME
                            WHEN BOTH PARTIES OPT OUT

<TABLE>
<CAPTION>
          PARTY A'S ROYALTY    PARTY A'S SHARE OF  PARTY B'S ROYALTY  PARTY B'S SHARE OF
        RATE AS AN OPTING OUT  ROYALTIES OR OTHER  RATE AS AN OPTING  ROYALTIES OR OTHER
                PARTY                INCOME            OUT PARTY            INCOME
<S>                            <C>                 <C>                <C>
</TABLE>
<PAGE>
    ATTACHMENT 9.1(b) THIRD PARTY AGREEMENTS RELATING TO EXCLUDED TECHNOLOGY

Technology Development Agreement dated as of March 20, 1989, between Sumitomo
Chemical Company, Limited and Regeneron Pharmaceuticals, Inc.

Collaboration Agreement dated as of August 31, 1990, between Amgen Inc. and
Regeneron Pharmaceuticals, Inc.

Collaboration Agreement dated as of July 22, 1993, between Glaxo Group Limited
and Regeneron Pharmaceuticals, Inc.

Research Development Agreement dated as of June 2, 1994, between Sumitomo
Pharmaceuticals Company, Ltd., and Regeneron Pharmaceuticals, Inc.

Collaboration Agreement dated as of October 9, 1996, between Pharmacopeia, Inc.,
and Regeneron Pharmaceuticals, Inc.

Collaborative Development Agreement dated as of June 27, 1996, between
Medtronic, Inc. and Regeneron Pharmaceuticals, Inc.

Memorandum of Understanding of an Agreement dated March 9,2000 between Medarex
Inc. and Regeneron Pharmaceuticals, Inc.
<PAGE>
                               ATTACHMENT 10.7(a)
                        EXAMPLE OF LICENSE FEE OPERATION

<TABLE>
<CAPTION>
                  SCENARIO                  LICENSE FEE OPERATION
<S>                                         <C>
</TABLE><PAGE>
                                                                   EXHIBIT 10.23

                             IL-1 LICENSE AGREEMENT

THIS LICENSE AGREEMENT dated this 26th day of June, 2002 by and among Regeneron
Pharmaceuticals, Inc., a New York corporation with principal offices located at
777 Old Saw Mill River Road, Tarrytown, New York 10591-6707 ("Regeneron"),
Immunex Corporation, a Washington corporation with principal offices located at
51 University Street, Seattle, Washington 98101 ("Immunex") and Amgen Inc., a
Delaware corporation with principal offices located at One Amgen Center Drive,
Thousand Oaks, California 91320-1799 (hereinafter referred to as "Amgen").

                                   WITNESSETH:

            WHEREAS, Regeneron is engaged in the research, development and
commercialization of human pharmaceutical products, including those certain
molecules in development known as the IL-1 Trap;

            WHEREAS, Immunex controls, and has the right to grant rights under,
certain patent rights relating to soluble IL-1 receptor proteins and is the
exclusive licensee of certain rights in, and has the right to grant sublicenses
under, certain patent rights relating to soluble IL-1 receptor proteins; and

            WHEREAS, Amgen controls, and has the right to grant rights under,
certain patent rights relating to soluble IL-1 receptor proteins;

            WHEREAS, the Federal Trade Commission staff has raised the concern
that the proposed merger between Amgen and Immunex is likely to produce
anticompetitive effects in an alleged IL-1 inhibitor market, which would not be
in the public interest, including, but not limited to, increasing the barriers
of entry into such market by the combination of Amgen's and Immunex's IL-1
inhibitor patent portfolios; and

            WHEREAS, in order to resolve the concerns raised by the Federal
Trade Commission staff in the alleged IL-1 inhibitor market, Amgen and Immunex
have agreed to grant certain rights under their respective patents to Regeneron
to permit Regeneron to commercialize such IL-1 Trap product and certain
follow-on IL-1 Trap products.

            NOW THEREFORE, in consideration of the foregoing and the covenants
and promises contained in this Agreement, the Parties agree as follows:

                                    ARTICLE 1

                                   DEFINITIONS

                                       1
<PAGE>
1.1 "AFFILIATE" shall mean a corporation or other business entity controlled by,
controlling, or under common control with a Party. For this purpose, control
shall mean the direct or indirect ownership of more than fifty percent (50%) of
the voting stock or at least fifty percent (50%) interest in the income of such
corporation or other business.

1.2 "AFTER-ACQUIRED PATENT RIGHTS" shall mean any Patent Rights which come to be
exclusively Controlled, in whole or part, by Amgen or Immunex (or, in either
case, any of its Affiliates) after the Effective Date, by license or acquisition
from a Third Party after the Effective Date, and which contain one or more
issued and enforceable claims that would be infringed by the making, having
made, using, offering for sale, selling or importing of a Licensed Product. It
is contemplated that After-Acquired Patent Rights can be acquired from a Third
Party possessing such Patent Rights through (x) a license agreement with such
Third Party, (y) the outright purchase of Patent Rights from such Third Party or
(z) due to a merger with a Third Party or acquisition of either voting control
or substantially all of the stock or assets of a Third Party Controlling through
ownership or exclusive license such Patent Rights.

1.3 "AGREEMENT" shall mean this License Agreement.

1.4 "AMGEN COMBINATION PRODUCT CLAIMS" shall mean, within Amgen Patent Rights,
composition of matter, article of manufacture and/or method of use claims
specifically requiring at least two (2) components with one recited component
being directed to or otherwise covering an interleukin-1 binding molecule and
the other recited component being directed to or otherwise covering an Other
Molecule(s). For the avoidance of doubt, Amgen Combination Product Claims shall
exclude any composition of matter, article of manufacture or method of use claim
not requiring both a component being directed to or otherwise covering an
interleukin-1 binding molecule and a component being directed to or otherwise
covering an Other Molecule(s).

1.5 "AMGEN LICENSED PATENT RIGHTS" shall mean, to the extent Controlled by Amgen
or any of its Affiliates: (i) the patent applications and patents listed on
Exhibit A; (ii) all national, regional and international patent applications
filed either from such patent applications or priority applications or from an
application claiming priority from either of these, including, without
limitation, divisionals, continuations, continuations-in-part, provisionals,
converted provisional, continued prosecution application; (iii) any and all
patents that have issued (including those set forth in Exhibit A) or in the
future issue from the foregoing patent applications, including, without
limitation, utility, model and design patents and certificates of invention; and
(iv) any and all extensions or restorations by existing or future extension or
restoration mechanisms, including without limitation, substitutions,
re-examinations, revalidations, reissues, renewals, extensions (including any
supplementary protection certificate) or any confirmation patent or registration
patent or patent of additions to any such foregoing patent applications and
patents. For the avoidance of doubt, After-Acquired Patent Rights are not
included in the definition of Amgen Licensed Patent Rights.

                                       2
<PAGE>
1.6 "AMGEN PATENT RIGHTS" shall mean all Patent Rights which are Controlled by
Amgen or any of its Affiliates and any After-Acquired Patent Rights included by
operation of Section 2.4(b). For the avoidance of doubt, Amgen Patent Rights
shall include Amgen Licensed Patent Rights.

1.7 "AVENTIS CONSENT AND AGREEMENT" shall mean a fully executed "Consent and
Agreement" by and between Aventis and Immunex, in substantially the form
attached hereto as Exhibit B. The fully executed Aventis Consent and Agreement
may vary from the form attached as Exhibit B as mutually acceptable to Immunex
and Regeneron, as affirmed in writing by Immunex and Regeneron.

1.8 "AVENTIS PASS-THROUGH ROYALTY" shall mean [********************************
*******].

1.9 "CONFIDENTIAL INFORMATION" shall mean (a) any information of any Party
disclosed to the other Party pursuant to this Agreement, which, if written, is
marked confidential by the disclosing Party or, if oral or by demonstration, is
reduced to writing, marked confidential by the disclosing Party, and provided to
a non-disclosing Party within thirty (30) days of the oral disclosure or
demonstration, (b) all information relating to the filing, prosecution,
maintenance, defense or enforcement of the Immunex Patent Rights or the Amgen
Patent Rights and (c) Regeneron's Net Sales.

1.10 "CONTROL" or "CONTROLLED" shall mean with respect to any Patent Right, in
each case the possession (whether by ownership, license or other right) by
Immunex or Amgen, as the case may be, or any of their Affiliates, of the ability
to grant to Regeneron rights as provided herein in either Sections 2.1, 2.3 or
2.4, as the case may be, without violating the terms of any written agreement
with any Third Party.

1.11 "CO-PROMOTER/CO-MARKETER" shall mean a Third Party contracted with by
Regeneron, its Affiliates or Sublicensees to engage in a part of the promotion,
marketing, detailing, sampling, distributing, and/or selling of any Licensed
Products. For purposes of this Agreement, a Co-Promoter/Co-Marketer shall be
permitted to conduct or sponsor post-approval clinical studies (in an approved
indication, but not necessarily for an approved use) with respect to a Licensed
Product. A Co-Promoter/Co-Marketer shall not be permitted to perform any part of
the pre-approval development of any indication of a Licensed Product, nor
perform any part of the bulk substance manufacturing of any Licensed Product.

1.12 "DEFAULT" shall mean with respect to a Party (i) that any representation or
warranty of such Party set forth herein shall have been untrue in any material
respect when made and/or (ii) such Party shall have failed to perform any
material obligation set forth herein; provided however, that such Party shall
have not brought such representation or warranty into conformance with such
representation or warranty or shall not have performed such material obligation,
within sixty (60) days after receipt of written notice from Regeneron (in the
case of Immunex and/or Amgen) and Immunex and/or Amgen (in the case of
Regeneron) specifying in detail the material obligation which has not been
performed and requesting that the failure to be remedied. (In those instances
where it is not possible for a Party to perform

                                       3
<PAGE>
a material obligation or bring a representation or warranty into conformance
within 60 days after receipt of such written notice, such Party shall have
satisfied its obligations to bring its representation or warranty into
conformance and/or to perform its material obligation and thus avoid Default by
commencing substantial remedial action within sixty (60) days after receipt of
the written notice, pursuing such remedial action with reasonable diligence and
completing such remedial action within one hundred twenty (120) after receipt of
the written notice.) For Regeneron, a "material obligation" as used above shall
be limited to [******************************************]. For the avoidance of
doubt, no act or failure to act by any Sublicensee or any other Third Party
shall be considered a Default on the part of Regeneron; provided however, this
sentence shall not be interpreted to relieve Regeneron (on behalf of itself, its
Affiliates or its Sublicensees) of any of its obligations to Amgen or Immunex as
set forth in this Agreement. Without limiting the foregoing, if any Sublicensee
shall engage in any activity described in Section 10.16 of the Agreement, the
specific provisions of Section 10.16 as they apply to the actions of the
Sublicensee shall apply, and such action by the Sublicensee in violation of the
covenant in Section 10.16 shall not be considered a Default on the part of
Regeneron.

1.13 "EFFECTIVE DATE" shall mean the date the Merger is consummated by filing
articles of merger related to the Merger with the Secretary of State of the
State of Washington.

1.14 "FIELD OF USE" shall mean all uses of Licensed Product(s).

1.15 "FIRST COMMERCIAL SALE" shall mean the initial transfer of commercial
quantities of Licensed Product to a Third Party following approval of the
Biologics License Application (or foreign equivalent) in exchange for cash or
some equivalent to which value can be assigned for purposes of determining Net
Sales.

1.16 "FORCE MAJEURE" shall mean any occurrence beyond the reasonable control of
a Party that prevents or substantially interferes with the performance by a
Party of any of its obligations hereunder, if and only if the Party affected
shall have used reasonable efforts to avoid such occurrence and to remedy it
promptly if it shall have occurred.

1.17 "GRANT COMMENCEMENT DATE" shall mean the later of (i) the Effective Date
and (ii) the date on which Immunex and Aventis have fully executed the Aventis
Consent and Agreement.

1.18 "IMMUNEX COMBINATION PRODUCT CLAIMS" shall mean, within Immunex Patent
Rights, composition of matter, article of manufacture and/or method of use
claims specifically requiring at least two (2) components with one recited
component being directed to or otherwise covering an interleukin-1 binding
molecule and the other recited component being directed to or otherwise covering
an Other Molecule(s)). For the avoidance of doubt, Immunex Combination Product
Claims shall exclude any composition of matter, article of manufacture or use
claim not requiring both a component being directed to or otherwise covering an
interleukin-1 binding molecule and a component being directed to or otherwise
covering an Other Molecule(s).

                                       4
<PAGE>
1.19 "IMMUNEX-HOECHST RECEPTOR AGREEMENT" shall mean that certain Receptor
Agreement dated April 6, 1998 by and between Immunex Corporation and Hoechst
Marion Roussel Deutschland GmbH, as the same may be amended from time to time,
including, without limitation, as modified by the Aventis Consent and Agreement.

1.20 "IMMUNEX-HOECHST PATENT RIGHTS" shall mean, to the extent Controlled by
Immunex, the "Behringwerke Receptor Patent Rights" as that term is defined in
the Immunex-Hoechst Receptor Agreement. A list of the Immunex-Hoechst Patent
Rights existing as of the Effective Date is set forth in Exhibit C.

1.21 "IMMUNEX LICENSED PATENT RIGHTS" shall mean, collectively, the Immunex
IL-1r Patent Rights and the Immunex-Hoechst Patent Rights. For the avoidance of
doubt, After-Acquired Patent Rights are not included in the definition of
Immunex Licensed Patent Rights.

1.22 "IMMUNEX IL-1R PATENT RIGHTS" shall mean, to the extent Controlled by
Immunex or any of its Affiliates: (i) the patent applications and patents listed
on Exhibit D; (ii) all national, regional and international patent applications
filed either from such patent applications or priority applications or from an
application claiming priority from either of these, including, without
limitation, divisionals, continuations, continuations-in-part, provisionals,
converted provisional, continued prosecution application; (iii) any and all
patents that have issued (including those set forth in Exhibit D) or in the
future issue from the foregoing patent applications, including, without
limitation, utility, model and design patents and certificates of invention; and
(iv) any and all extensions or restorations by existing or future extension or
restoration mechanisms, including without limitation, substitutions,
re-examinations, revalidations, reissues, renewals, extensions (including any
supplementary protection certificate) or any confirmation patent or registration
patent or patent of additions to any such foregoing patent applications and
patents.

1.23 "IMMUNEX PATENT RIGHTS" shall mean all Patent Rights which are Controlled
by Immunex, or any of its Affiliates and any After-Acquired Patent Rights
included by operation of Section 2.3(b). For the avoidance of doubt, Immunex
Patent Rights shall include Immunex Licensed Patent Rights.

1.24 "INTERLEUKIN-1 RECEPTOR" shall mean, [*******************************].

1.25 "LICENSED PRODUCT(S)" shall mean a molecule, or gene encoding a molecule,
comprising (i) all or an interleukin-1 binding portion of the amino acid
sequence for [******************************************]; and (ii)
[****************************]. For the avoidance of doubt, a Licensed Product
may be a [***********************]. For the further avoidance of doubt, the TRAP
Product shall be included within the definition of Licensed Product. [**********
******************].

1.26 "LOSSES" shall mean liabilities, costs, settlements, damages, expenses
and/or losses, including reasonable attorneys' fees, except as set forth in
Section 7.1(c).

                                       5
<PAGE>
1.27 "MERGER" shall mean the merger between AMS Acquisition Inc. (a Washington
corporation and wholly owned subsidiary of Amgen) and Immunex as contemplated in
the Amended and Restated Agreement and Plan of Merger by and among Amgen Inc.,
AMS Acquisition Inc. and Immunex Corporation dated as of December 16, 2001 (or
any other means of effecting the merger between Amgen and Immunex).

1.28 "NET SALES" shall mean [************************************].

1.29 "OTHER MOLECULE(S)" shall mean any active ingredient or finished product
containing an active ingredient (or class of active ingredient(s) or finished
product(s) containing an active ingredient(s)) that is not a Licensed Product
(e.g. a TNF inhibitor).

1.30 "PARTY" shall mean Amgen, Immunex or Regeneron, as the case may be, and
"PARTIES" shall mean Amgen, Immunex and Regeneron, collectively.

1.31 "PATENT RIGHTS" shall mean all pending patent applications and issued
patents, in each case as of the Effective Date; and, solely with respect to the
subject matter contained in such patent applications and issued patents, (i) all
national, regional and international patent applications filed either from such
patent applications or priority applications or from an application claiming
priority from either of these, including, without limitation, divisionals,
continuations, continuations-in-part, provisionals, converted provisional,
continued prosecution application, (ii) any and all patents that have issued or
in the future issue from the foregoing patent applications, including, without
limitation, utility, model and design patents and certificates of invention, and
(iii) any and all extensions or restorations by existing or future extension or
restoration mechanisms, including without limitation, substitutions,
re-examinations, revalidations, reissues, renewals, extensions (including any
supplementary protection certificate) or any confirmation patent or registration
patent or patent of additions to any such foregoing patent applications and
patents.

1.32 "PERSON" shall mean an individual, a partnership, a joint venture, a
corporation, a trust, an estate, an unincorporated organization, or any other
entity, or a government or any department or agency thereof.

1.33 "PROMOTE", as used in Section 2.3(a) and Section 2.4(a), shall mean any
activity in connection with the promotion, marketing and/or detailing of a
product. For the avoidance of doubt, the making and/or actual selling and/or
distribution of a product shall not be included within the definition of
Promote.

1.34 "SUBLICENSEE" shall mean a Third Party to whom Regeneron has granted a
sublicense pursuant to Section 2.2.

1.35 "TERRITORY" shall mean all countries of the world.

1.36 "THIRD PARTY" shall mean any Person other than Amgen, Immunex, Regeneron,
and their respective Affiliates.

                                       6
<PAGE>
1.37 "TRAP PRODUCT" shall mean a molecule comprising (i)
[**********************************]; and (ii) all or a portion (which portion
must, together with the polypeptide having the sequence referenced in subsection
(i) above, participate in the binding of interleukin-1) of the interleukin-1
accessory protein as described by [****************************]; wherein the
molecule is capable of binding interleukin-1. By way of example, TRAP Products
shall include the product identified [******************************]. For
avoidance of doubt, TRAP Product is included within the definition of Licensed
Product. [************************************].

                                    ARTICLE 2

                                 GRANT OF RIGHTS

2.1      GRANT TO REGENERON.

         (a) On the terms and conditions set forth herein, Immunex hereby grants
to Regeneron and its Affiliates a non-exclusive license, with a limited right to
grant sublicenses solely pursuant to Section 2.2 herein, under the Immunex
Licensed Patent Rights to make, have made, use, sell, offer for sale and import
Licensed Products in the Field of Use anywhere in the Territory.

         (b) On the terms and conditions set forth herein, Amgen hereby grants
to Regeneron and its Affiliates a non-exclusive license, with a limited right to
grant sublicenses solely pursuant to Section 2.2 herein, under the Amgen
Licensed Patent Rights to make, have made, use, sell, offer for sale and import
Licensed Products in the Field of Use anywhere in the Territory.

2.2 SUBLICENSES. Regeneron shall have the limited right to grant sublicenses
under the rights granted under Sections 2.1(a) and 2.1(b) on a country by
country basis, to [******************************]. For the avoidance of doubt,
[**************************] shall not be considered a Sublicensee for purposes
of this Section 2.2. Regeneron acknowledges and agrees that any sublicense
granted pursuant to this Section 2.2 shall be consistent with, and expressly
subject to, the covenants, terms and conditions set forth in this Agreement, and
shall terminate upon termination of this Agreement. Regeneron, its Affiliates
and each Sublicensee shall each be permitted to engage the services of one or
more Co-Promoters/Co-Marketers in any country in the Territory. For the
avoidance of doubt, in addition to the sublicensing rights set forth in this
Section 2.2, Regeneron and its Affiliates shall have the right to engage the
services of a contract sales force in any country in the Territory and such
service providers shall not be considered Sublicensees for purposes of this
Section 2.2. [***************************]. Regeneron agrees to remain liable
for the obligations, including the payment of royalties, of each Sublicensee as
required pursuant to this Agreement; provided that no act or failure to act by
any Sublicensee can be considered a Default on the part of Regeneron (but
Regeneron shall remain liable for its obligations (and the obligations of its
Affiliates and each Sublicensee) to Amgen or Immunex under this Agreement).

                                       7
<PAGE>
2.3      IMMUNEX COVENANT NOT TO SUE.

         (a) Neither Immunex nor any of its Affiliates shall ever, anywhere in
the world, institute or prosecute (or in any way aid any Third Party in
instituting or prosecuting), at law or in equity, any claim, demand, action or
cause of action for damages, costs, expenses or compensation, or for an
enjoinment, injunction, or any other equitable remedy, against Regeneron, its
Affiliates, Sublicensees, suppliers, distributors, Co-Promoters/Co-Marketers,
vendors or customers alleging the infringement of any Immunex Patent Rights in
its making, having made, using, selling, offering to sell, or importing of (i)
any Licensed Product, or (ii) any product which includes or incorporates a
Licensed Product in any manner to the extent that the alleged infringement is
based on the manufacture, use, sale, offer to sell, or importation of the
Licensed Product or Licensed Product portion in such product.

         Pursuant to this covenant, Regeneron, its Affiliates, Sublicensees,
suppliers, distributors, Co-Promoters/Co-Marketers, vendors or customers may,
under Immunex Patent Rights, make, have made, use, sell, offer to sell or import
any Licensed Product in combination with an Other Molecule(s). Notwithstanding
the foregoing, if the making, having made, using, offering to sell, selling or
importing of an Other Molecule(s) would infringe any claim within the Immunex
Patent Rights, other than in any Immunex Combination Product Claims, Regeneron,
its Affiliates, Sublicensees, suppliers, distributors,
Co-Promoters/Co-Marketers, vendors or customers shall have no right under such
claims to make, have made, use, offer to sell, sell or import such Other
Molecule(s), except that Regeneron, its Affiliates, Sublicensees and
Co-Promoters/Co-Marketers shall have the right under all Immunex Patent Rights
solely to pre-clinically and clinically test and to Promote the combination use
of such Other Molecule(s) with the Licensed Product.

         Immunex further covenants and agrees that, in the event Immunex or its
Affiliate grants or transfers any rights under any Immunex Patent Rights which,
Immunex in good faith believes is reasonably likely to be subject to this
covenant, to any Third Party, such grant or transfer of rights shall be only
upon the condition that the Third Party agrees, in writing, to grant Regeneron,
its Affiliates, Sublicensees, suppliers, distributors,
Co-Promoters/Co-Marketers, vendors and customers immunity from suit as set forth
in this Section 2.3(a) and agrees to Regeneron being a third party beneficiary
under such grant or transfer to the extent it relates to such immunity from
suit. For the avoidance of doubt, subject to Section 8.3, the preceding sentence
shall not operate to require Immunex or its Affiliates to maintain or renew any
Third Party agreement pursuant to which it currently has Control of any Immunex
Patent Rights; subject to Section 8.3, the reversion of rights to the original
possessor thereof upon such failure to maintain or renew such Third Party
agreement shall not be considered a grant or transfer that is subject to the
requirements of the first sentence of this paragraph, unless such reversion is
the result of a new agreement with such Third Party pursuant to which such Third
Party pays consideration to Immunex or its Affiliates in connection with the
reversion.

         (b) In the event that Immunex or any of its Affiliates comes to Control
After-Acquired Patent Rights, Immunex (on its own behalf and on behalf of its
Affiliates)

                                       8
<PAGE>
covenants to use good faith efforts to obtain, as part of its "Control", the
right to grant to Regeneron those rights obtainable on the following conditions
and Regeneron shall have the right to include such After-Acquired Patent Rights
within the definition of Immunex Patent Rights solely on the following
conditions:

                  (i) At any time following Immunex or any of its Affiliates
coming to Control any After-Acquired Patent Rights, either Immunex or Regeneron
may provide written notice to the other that such After-Acquired Patents Rights
are to be considered for inclusion within the definition of the Immunex Patent
Rights ("Initial Notice"). Regardless of which Party provides the Initial
Notice, within thirty (30) days after such Initial Notice, Immunex shall provide
to Regeneron a description of the relevant circumstances related to the
acquisition of the After-Acquired Patent Rights, and shall inform Regeneron of
the consequent consideration required for Regeneron to include such
After-Acquired Patent Rights (the "Offered After-Acquired Patent Rights") within
the definition of Immunex Patent Rights, as set forth below and in Exhibit E,
attached hereto. Such notice (the "Offering Notice") shall include (a) complete
copies of any patents included in such Offered After-Acquired Patent Rights, and
[*******************************************]. Immunex shall use all reasonable
efforts to obtain any necessary consents from the relevant Third Party to permit
the disclosure to Regeneron of the information required in the Offering Notice.
Immunex shall be required to respond promptly to all reasonable questions raised
by Regeneron in connection with Regeneron's review of the Offered After-Acquired
Patent Rights and the contractual provisions. Regeneron shall have the right,
within ninety (90) days after receipt of such notice, to notify Immunex in
writing whether Regeneron elects to include such patents in the Immunex Patent
Rights, and [********************]. Upon such election, the Offered
After-Acquired Patent Rights shall thereafter be included in the definition of
Immunex Patent Rights; if Regeneron elects not to agree to such consideration
with respect to the Offered After-Acquired Patent Rights, or fails to timely
make its election, any such Offered After-Acquired Patent Rights shall continue
to be excluded from the definition of Immunex Patent Rights. Regeneron shall
have the right to terminate its license for any After-Acquired Patent Rights on
thirty (30) days prior written notice signed by a duly authorized officer of
Regeneron; the effect of such termination shall be that such After-Acquired
Patent Rights shall thereafter be excluded from the definition of Immunex Patent
Rights. For the avoidance of doubt, each After-Acquired Patent Right (or set of
rights) is only subject to the Regeneron option for inclusion set forth in this
subsection on one occasion; that is, if Regeneron elects not to agree to include
Offered After-Acquired Patent Rights within the Immunex Patent Rights (or fails
to timely make such election) following the Offering Notice with respect to such
Offered After-Acquired Patent Rights, Regeneron shall not have the option to
later include those same Offered After-Acquired Patent Rights within the Immunex
Patent Rights. For the avoidance of doubt, the rejection of a particular patent
or claim offered as an Offered After-Acquired Patent Right under this Section
shall not operate to limit Regeneron's rights with respect to any other issued
patents or claims that were not offered as Offered After-Acquired Patent Rights,
even if such patent or claims which were not offered were obtained from the same
Third Party, or pursuant to the same Third Party Agreement, as the Offered
After-Acquired Patent Rights which were rejected.

         For the avoidance of doubt, any intellectual property rights acquired
by Immunex after the Effective Date (such that Immunex's or its Affiliate's
rights to the applicable

                                       9
<PAGE>
patents and/or patent applications first arise after the Effective Date) shall
be excluded from the definition of Immunex Patent Rights unless meeting the
definition of After-Acquired Patent Rights and specifically included by
operation of this Section 2.3(b).

         [****************************************]

         [****************************************]

         [****************************************]

         For the avoidance of doubt, each distinct time Immunex obtains Control
of After-Acquired Patent Rights, this Section 2.3(b)
[***************************************] shall operate. All After-Acquired
Patent Rights obtained in one transaction (or series of related transactions)
from one Third Party shall be considered a set, and this Section 2.3(b)
[******************************) shall apply only once to such a set of
After-Acquired Patent Rights, regardless of how many patents or patent
applications are acquired in that one transaction (or series of related
transactions).

         (c) Notwithstanding 2.3(a) above,
[************************************], Immunex shall provide reasonably timely
notice to Regeneron of the Third Party obligation with respect to any such
patent. Such notice (the "Offering Notice") shall include (a) complete copies of
any patents included in such Pass-Through Patent Rights, and
[*********************************]. Immunex shall use all reasonable efforts to
obtain any necessary consents from the relevant Third Party to permit the
disclosure to Regeneron of the information required in the notice contemplated
herein. Immunex shall be required to respond promptly to all reasonable
questions raised by Regeneron in connection with Regeneron's review of the
Pass-Through Patent Rights and the contractual provisions. Regeneron shall have
the right, [****************************************]. Upon such election, the
Pass-Through Patent Rights shall thereafter be included in the definition of
Immunex Patent Rights; if Regeneron elects not to accept such obligation with
respect to any patent or fails to timely make its election, any such patent
shall be excluded from the definition of Immunex Patent Rights. Regeneron shall
have the right to terminate its license of any Pass-Through Patent Rights on
thirty (30) days prior written notice signed by a duly authorized officer of
Regeneron. For the avoidance of doubt, each Pass-Through Patent Right (or set of
rights) is only subject to the Regeneron option for inclusion set forth in this
subsection on one occasion; that is, if Regeneron elects not to agree to include
Pass-Through Patent Rights within the Immunex Patent Rights (or fails to timely
make such election) following the Offering Notice with respect to such
Pass-Through Patent Rights, Regeneron shall not have the option to later include
those same Pass-Through Patent Rights within the Immunex Patent Rights.

      This Section 2.3(c) shall not apply with respect to [********************
**************].

                                       10
<PAGE>
         (d) For the avoidance of doubt, the covenants set forth in Section
2.3(a) above shall terminate upon the termination of this Agreement, including,
without limitation, any termination arising from the breach of this Agreement by
Regeneron.

2.4      AMGEN COVENANT NOT TO SUE.

         (a) Neither Amgen nor any of its Affiliates shall ever, anywhere in the
world, institute or prosecute (or in any way aid any Third Party in instituting
or prosecuting), at law or in equity, any claim, demand, action or cause of
action for damages, costs, expenses or compensation, or for an enjoinment,
injunction, or any other equitable remedy, against Regeneron, its Affiliates,
Sublicensees, suppliers, distributors, Co-Promoters/Co-Marketers, vendors or
customers alleging the infringement of any Amgen Patent Rights in its making,
having made, using, selling, offering to sell, or importing of (i) any Licensed
Product, or (ii) any product which includes or incorporates a Licensed Product
in any manner to the extent that the alleged infringement is based on the
manufacture, use, sale, offer to sell, or importation of the Licensed Product or
Licensed Product portion in such product.

         Pursuant to this covenant, Regeneron, its Affiliates, Sublicensees,
suppliers, distributors, Co-Promoters/Co-Marketers, vendors or customers may,
under Amgen Patent Rights, make, have made, use, sell, offer to sell or import
any Licensed Product in combination with an Other Molecule(s). Notwithstanding
the foregoing, if the making, having made, using, offering to sell, selling or
importing of an Other Molecule(s) would infringe any claim within the Amgen
Patent Rights, other than in any Amgen Combination Product Claims, Regeneron,
its Affiliates, Sublicensees, suppliers, distributors, Co-Promoters/
Co-Marketers, vendors or customers shall have no right under such claims to
make, have made, use, offer to sell, sell or import such Other Molecule(s),
except that Regeneron, its Affiliates, Sublicensees and
Co-Promoters/Co-Marketers shall have the right under all Amgen Patent Rights
solely to pre-clinically and clinically test and to Promote the combination use
of such Other Molecule(s) with the Licensed Product.

         Amgen further covenants and agrees that, in the event Amgen or its
Affiliate grants or transfers any rights under any Amgen Patent Rights which,
Amgen in good faith believes is reasonably likely to be subject to this
covenant, to any Third Party, such grant or transfer of rights shall be only
upon the condition that the Third Party agrees, in writing, to grant Regeneron,
its Affiliates, Sublicensees, suppliers, distributors, Co-Promoters/
Co-Marketers, vendors and customers immunity from suit as set forth in this
Section 2.4(a) and agrees to Regeneron being a third party beneficiary under
such grant or transfer to the extent it relates to such immunity from suit. For
the avoidance of doubt, subject to Section 8.3, the preceding sentence shall not
operate to require Amgen or its Affiliates to maintain or renew any Third Party
agreement pursuant to which it currently has Control of any Amgen Patent Rights;
subject to Section 8.3, the reversion of rights to the original possessor
thereof upon such failure to maintain or renew such Third Party agreement shall
not be considered a grant or transfer that is subject to the requirements of the
first sentence of this paragraph, unless such reversion is the result of a new
agreement with such Third Party pursuant to which such Third Party pays
consideration to Amgen or its Affiliates in connection with the reversion.

                                       11
<PAGE>
         (b) In the event that Amgen or any of its Affiliates comes to Control
After-Acquired Patent Rights, Amgen (on its own behalf and on behalf of its
Affiliates) covenants to use good faith efforts to obtain, as part of its
"Control", the right to grant to Regeneron those rights obtainable on the
following conditions and Regeneron shall have the right to include such
After-Acquired Patent Rights within the definition of Amgen Patent Rights,
solely on the following conditions:

                  (i) At any time following Amgen or any of its Affiliates
coming to Control any After-Acquired Patent Rights, either Amgen or Regeneron
may provide written notice to the other that such After-Acquired Patents Rights
are to be considered for inclusion within the definition of the Amgen Patent
Rights ("Initial Notice"). Regardless of which Party provides the Initial
Notice, within thirty (30) days after such Initial Notice, Amgen shall provide
to Regeneron a description of the relevant circumstances related to the
acquisition of the After-Acquired Patent Rights, and shall inform Regeneron of
the consequent consideration required for Regeneron to include such
After-Acquired Patent Rights (the "Offered After-Acquired Patent Rights") within
the definition of Amgen Patent Rights, as set forth below and in Exhibit E,
attached hereto. Such notice (the "Offering Notice") shall include (a) complete
copies of any patents included in such Offered After-Acquired Patent Rights, and
[*************************************]. Amgen shall use all reasonable efforts
to obtain any necessary consents from the relevant Third Party to permit the
disclosure to Regeneron of the information required in the Offering Notice.
Amgen shall be required to respond promptly to all reasonable questions raised
by Regeneron in connection with Regeneron's review of the Offered After-Acquired
Patent Rights and the contractual provisions. Regeneron shall have the right,
within ninety (90) days after receipt of such notice, to notify Amgen in writing
whether Regeneron elects to include such Patents in the Amgen Patent Rights,
[*******************************]. Upon such election, the Offered
After-Acquired Patent Rights shall thereafter be included in the definition of
Amgen Patent Rights; if Regeneron elects not to agree to such consideration with
respect to the Offered After-Acquired Patent Rights, or fails to timely make its
election, any such Offered After-Acquired Patent Rights shall continue to be
excluded from the definition of Amgen Patent Rights. Regeneron shall have the
right to terminate its license for any After-Acquired Patent Rights on thirty
(30) days prior written notice signed by a duly authorized officer of Regeneron;
the effect of such termination shall be that such After-Acquired Patent Rights
shall thereafter be excluded from the definition of Amgen Patent Rights. For the
avoidance of doubt, each After-Acquired Patent Right (or set of rights) is only
subject to the Regeneron option for inclusion set forth in this subsection on
one occasion; that is, if Regeneron elects not to agree to include Offered
After-Acquired Patent Rights within the Amgen Patent Rights (or fails to timely
make such election) following the Offering Notice with respect to such Offered
After-Acquired Patent Rights, Regeneron shall not have the option to later
include those same Offered After-Acquired Patent Rights within the Amgen Patent
Rights. For the avoidance of doubt, the rejection of a particular patent or
claim offered as an Offered After-Acquired Patent Right under this Section shall
not operate to limit Regeneron's rights with respect to any other issued patents
or claims that were not offered as Offered After-Acquired Patent Rights, even if
such patent or claims which were not offered were obtained from the same Third
Party, or pursuant to the same Third Party Agreement, as the Offered
After-Acquired Patent Rights which were rejected.

                                       12
<PAGE>
         For the avoidance of doubt, any intellectual property rights acquired
by Amgen after the Effective Date (such that Amgen's or its Affiliate's rights
to the applicable patents and/or patent applications first arise after the
Effective Date) shall be excluded from the definition of Amgen Patent Rights
unless meeting the definition of After-Acquired Patent Rights and specifically
included by operation of this Section 2.4(b).

                  [*******************************************]

                  [*******************************************]

                  [*******************************************]

         For the avoidance of doubt, each distinct time Amgen obtains Control of
After-Acquired Patent Rights, this Section 2.4(b) [****************************]
shall operate. All After-Acquired Patent Rights obtained in one transaction (or
series of related transactions) from one Third Party shall be considered a set,
and this Section 2.4(b) [*******************************************] shall
apply only once to such a set of After-Acquired Patent Rights, regardless of how
many patents or patent applications are acquired in that one transaction (or
series of related transactions).

         (c) [***********************************************************],
Amgen shall provide reasonably timely notice to Regeneron of the Third Party
obligation with respect to any such patent. Such notice (the "Offering Notice")
shall include (a) complete copies of any patents included in such Pass-Through
Patent Rights, [*******************************************************] Amgen
shall use all reasonable efforts to obtain any necessary consents from the
relevant Third Party to permit the disclosure to Regeneron of the information
required in the notice contemplated herein. Amgen shall be required to respond
promptly to all reasonable questions raised by Regeneron in connection with
Regeneron's review of the Pass-Through Patent Rights and the contractual
provisions.[*******************************************************************]
Upon such election, the Pass-Through Patent Rights shall thereafter be included
in the definition of Amgen Patent Rights; if Regeneron elects not to accept such
obligation with respect to any patent or fails to timely make its election, any
such patent shall be excluded from the definition of Amgen Patent Rights.
Regeneron shall have the right to terminate its license of any Pass-Through
Patent Rights on thirty (30) days prior written notice signed by a duly
authorized officer of Regeneron. For the avoidance of doubt, each Pass-Through
Patent Right (or set of rights) is only subject to the Regeneron option for
inclusion set forth in this subsection on one occasion; that is, if Regeneron
elects not to agree to include Pass-Through Patent Rights within the Amgen
Patent Rights (or fails to timely make such election) following the Offering
Notice with respect to such Pass-Through Patent Rights, Regeneron shall not have
the option to later include those same Pass-Through Patent Rights within the
Amgen Patent Rights.

         This Section 2.4(c) shall not apply [*********************************
************************]

                                       13
<PAGE>
         (d) For the avoidance of doubt, the covenants set forth in Section
2.4(a) above shall terminate upon the termination of this Agreement, including,
without limitation, any termination arising from the breach of this Agreement by
Regeneron.

2.5 NO OTHER RIGHTS. Except for the rights expressly granted under this
Agreement, no right, title or interest of any nature is granted under this
Agreement by any Party to any other Party, or any Affiliate of any Party, or to
any Third Party. For the avoidance of doubt, Amgen and Immunex are only
licensing Patent Rights under this Agreement and neither Amgen nor Immunex (nor
any of their respective Affiliates) shall have any obligation to transfer or
grant licenses to any know-how including, without limitation, trade secrets,
inventions, information and data, results, and materials, even if such know-how
is claimed by any Patent Rights subject to this Agreement. The Parties
acknowledge that the Amgen Licensed Patent Rights and the Immunex Licensed
Patent Rights include claims not covering Licensed Product(s), as defined
herein, such as claims only covering TNF receptors, and the Parties further
acknowledge that it is not the intent of the Parties to convey to Regeneron any
rights to such claims pursuant to this Agreement.

2.6 CONDITION PRECEDENT. For the avoidance of doubt, all licenses and other
rights provided in this Article 2 shall commence effective as of the Grant
Commencement Date.

                                    ARTICLE 3

                                  CONSIDERATION

3.1 ROYALTIES. In consideration for the licenses and other rights granted under
Article 2, Regeneron agrees to pay royalties with respect to its total sales of
Licensed Product if and to the extent required by the terms of Article 3.

         (a) Regeneron shall pay to Immunex (or Amgen if applicable) a royalty,
calculated as a sum of the following royalties:

         (i) Base Royalty. (A) [*******************************] of each
Licensed Product in any country in the Territory if the making, having made,
using, offering to sell, selling or importing of such Licensed Product by
Regeneron, its Affiliates or its Sublicensees (or the distributors of any of
them), in the absence of this Agreement, would infringe one or more issued
claims of the Immunex Licensed Patent Rights in the country where such making,
having made, using, offering to sell, selling or importing took place, that have
not lapsed, been abandoned or been declared invalid by an unappealable judgment
of a court of competent jurisdiction in such country.

                           (B) In the event that sales of a Licensed Product by
Regeneron would not trigger a royalty payment pursuant to Section 3.1(a)(i)(A)
above, but the making, having made, using, offering to sell, selling or
importing of such Licensed Product by Regeneron, its

                                       14
<PAGE>
Affiliates or its Sublicensees (or the distributors of any of them), in the
absence of this Agreement, would infringe one or more issued claims of the Amgen
Licensed Patent Rights in the country where such making, having made, using,
offering to sell, selling or importing took place, that have not lapsed, been
abandoned or been declared invalid by an unappealable judgment of a court of
competent jurisdiction in any such country, Regeneron shall pay
[************************] of each such Licensed Product in such country to
Amgen, rather than Immunex. For the avoidance of doubt, if a royalty is due
Immunex under Section 3.1(a)(i)(A), no royalty shall be due Amgen pursuant to
this Section 3.1(a)(i)(B).

                           (C) In the event that sales of a Licensed Product by
Regeneron would not trigger a royalty payment pursuant to Section 3.1(a)(i)(A)
above nor pursuant to Section 3.1(a)(i)(B) above, but the making, having made,
using, offering to sell, selling or importing of such Licensed Product by
Regeneron, its Affiliates or its Sublicensees (or the distributors of any of
them), infringe or in the absence of this Agreement, would infringe one or more
issued claims of the Immunex Patent Rights or Amgen Patent Rights subject to the
covenants contained in Section 2.3(a) above or Section 2.4(a) above, in the
country where such making, having made, using, offering to sell, selling or
importing took place, that have not lapsed, been abandoned or been declared
invalid by an unappealable judgment of a court of competent jurisdiction in any
such country, Regeneron shall pay [**************************] of each such
Licensed Product in such country to Immunex or Amgen, as appropriate, based on
whether it is the Immunex Patent Rights that are implicated or the Amgen Patent
Rights. (If both, payment shall be made half to Immunex, and half to Amgen.) For
the avoidance of doubt, if a royalty is due under either Section 3.1(a)(i)(A) or
Section 3.1(a)(i)(B) with respect to a Licensed Product, no royalty shall be due
pursuant to this Section 3.1(a)(i)(C) with respect to such Licensed Product.

                           (D) For the avoidance of doubt, in no event shall the
royalty payments pursuant to this Section 3.1(a)(i) exceed
[*************************] of each Licensed Product subject to the royalty
provisions of (A), (B) and/or (C) above.

                  (ii) Aventis Pass-Through Royalty. Regeneron shall pay to
Immunex [***********************************************************]unless all
of the issued claims of the Amgen Patent Rights and Immunex Patent Rights,
collectively, expire prior to the royalty term specified in the Aventis Consent
and Agreement, in which case, from the time of such expiration, royalties shall
no longer be due under this Section 3.1(ii).

                           (A) Acknowledgement. Regeneron and Immunex
                  acknowledge that the Aventis Pass-Through Royalty is owed by
                  Immunex to Aventis under the Immunex-Hoechst Receptor
                  Agreement (as modified by the Aventis Consent and Agreement)
                  on sales of any Licensed Products by Regeneron under this
                  Agreement, for the duration and under such terms set forth in
                  the Aventis Consent and Agreement, provided the
                  Immunex-Hoechst Receptor Agreement has not expired or been
                  terminated. [**************************************]

         (b) [*****************************************************]

         (c) [*****************************************************]

                                       15
<PAGE>
3.2 COMPENSATION TERM.

             (a) Unless this Agreement is earlier terminated in accordance with
                 Article 9 hereof, Regeneron's obligation to pay royalties under
                 Section 3.1(a) shall expire on a Licensed Product-by-Licensed
                 Product and country-by-country basis:

                 (i)      under Section 3.1(a)(i), [**************************
                          *****]

                 (ii)     under Section 3.1(a)(ii), [*************************
                          ******]

             (b) [******************************************]

             (c) [******************************************]

             (d) [************************************]

3.3 [************************************************************]

3.4 PAYMENT OF ROYALTIES; REPORTS.

         (a) First Commercial Sale. Regeneron shall report to an independent
certified public accountant chosen jointly by Amgen and Immunex and reasonably
acceptable to Regeneron ("Independent Accountant") the date of First Commercial
Sale of a Licensed Product in each country in the Territory within
[****************] after such occurrence.[************************************].

         (b) Statements. Beginning with the calendar quarter during which
occurred the First Commercial Sale of a Licensed Product, Regeneron shall
deliver to Independent Accountant, within [***************] after the end of
each calendar quarter, a statement separately setting forth
[**********************************************].

         (c) Currency. If Net Sales are received in a currency other than United
States Dollars, the Net Sales for the purpose of calculating payments hereunder
shall be determined in the applicable foreign currency and then converted into
its equivalent in United States Dollars at the rate of exchange applicable on
the last business day of the calendar quarter in respect of which the funds are
payable using the currency exchange rates quoted by the Wall Street Journal,
Eastern Edition, during the period of such Net Sales.
[**************************************]

         (d) Taxes. [***********************************************] Regeneron
will furnish Immunex or Amgen, as appropriate, with the original copies of all
official receipts for such taxes. In the event of any such withholding,
Regeneron and

                                       16
<PAGE>
Immunex or Amgen, as appropriate, shall confer regarding other measures to
minimize such withholding.

         (e) Overdue Payments. Overdue payments hereunder shall be subject to a
late payment charge calculated at an annual rate of
[****************************]. If the amount of such charge exceeds the maximum
permitted by law, such charge shall be reduced to such maximum.

                                    ARTICLE 4

                                 RECORDS; AUDIT

4.1 RECORD RETENTION. Regeneron shall use commercially reasonable efforts to
maintain, and shall use commercially reasonable efforts (which shall include
obtaining and enforcing a contractual commitment) to cause each of its
Affiliates and its Sublicensees to maintain, full, true and accurate books and
records, in all material respects, containing particulars required to determine
the correctness of any payment of royalties due pursuant to this Agreement. Such
records shall be retained for at least the longer of one (1) year after
completion of an audit thereof pursuant to Section 4.2 if an audit has been
requested or of three (3) years following the year in which any such payments
were made hereunder.

4.2 ROYALTY AUDIT. [*************************], Regeneron agrees to make its
records for payment of royalties due, available for examination by the
Independent Accountant at the expense of Amgen and Immunex (except as otherwise
set forth in this Section 4.2), to examine, in confidence (upon at least thirty
(30) days prior written notice and during Regeneron's regular business hours),
Regeneron's records as may be necessary to determine the correctness of any
payment of royalties hereunder made by Regeneron. Regeneron shall enter into a
separate confidentiality agreement directly with such Independent Accountant.
The report of such Independent Accountant shall be limited to a certificate
verifying any report made or payment submitted by Regeneron during such period
but may include, in the event the Independent Accountant shall be unable to
verify the correctness of any or all of such payment, the unverifiable amount of
such payment and information relating to why any or all of such payment is
unverifiable, and Regeneron shall receive a copy of each such report
concurrently with receipt by Immunex or Amgen, as appropriate. All information
contained in any such certificate shall be deemed to be the Confidential
Information of Regeneron. [****************************************]

                                    ARTICLE 5

                                     PATENTS

5.1 IMMUNEX PATENT RIGHTS. As among the Parties, Immunex shall have the sole
right, at its sole discretion and at its expense, to file, prosecute, defend,
maintain (subject to Section 8.3) and enforce Immunex Patent Rights.

                                       17
<PAGE>
5.2 AMGEN PATENT RIGHTS. As among the Parties, Amgen shall have the sole right,
at its sole discretion and expense, to file, prosecute, defend, maintain
(subject to Section 8.3) and enforce Amgen Patent Rights.

5.3 PATENT STATUS. Immunex and Amgen each agrees to keep Regeneron advised on of
the status of patent applications and patents within (i) Amgen Patent Rights and
Immunex Patent Rights, as appropriate, for which compensation is then being paid
by Regeneron, (ii) the Amgen Licensed Patent Rights and (iii) the Immunex
Licensed Patent Rights, upon reasonable written request by Regeneron, no more
than once per calendar year.

5.4 NOTIFICATION OF INFRINGEMENT. If Regeneron learns of an infringement by a
Third Party of the Immunex Licensed Patent Rights or the Amgen Licensed Patent
Rights, Regeneron shall promptly notify and shall provide Immunex and Amgen with
available evidence of such infringement.

                                    ARTICLE 6

                                 CONFIDENTIALITY

6.1 CONFIDENTIALITY. For the term of this Agreement and any extensions and for a
period of five (5) years thereafter, each Party agrees to keep confidential and
not publish or otherwise disclose or use for any purpose other than as provided
for in this Agreement, any Confidential Information disclosed to it by another
Party, except that each Party receiving such Confidential Information shall not
be prevented from using or disclosing information:

         (a) which it can demonstrate by written records was previously known to
it;

         (b) which is, or becomes in the future, public knowledge through no
fault or omission attributable to it;

         (c) which is lawfully obtained without restriction by it from sources
independent of the disclosing Party without breach of a confidentiality
obligation; or

         (d) which was independently discovered or developed by the disclosing
Party without access to or the use of the disclosing Party's Confidential
Information, as can be documented by written records created at the time of such
independent discovery or development.

6.2. THIS AGREEMENT. The Parties agree that the material terms of the Agreement
shall be considered Confidential Information of all Parties. Notwithstanding the
foregoing, the Parties shall be permitted to disclose in filings with the
Securities Exchange Commission ("SEC") and the Federal Trade Commission ("FTC")
those terms of this Agreement required to be disclosed to either of those
agencies by law or regulation; provided, however, that the Parties shall consult
with one another concerning which terms of this Agreement shall be requested to
be redacted by the SEC or FTC in any public filings by such agencies and,

                                       18
<PAGE>
further provided, however, that in the event of a filing, each Party shall seek
confidential treatment in its SEC filings and FTC filings for the royalty rates
set forth in Article 3. In addition, Regeneron shall have the right to issue a
press release concerning this Agreement substantially in the form annexed hereto
as Exhibit F, or, if not provided in Exhibit F, subject to the consent of Amgen
and Immunex, following a reasonable opportunity for review (not to exceed three
(3) business days), such consent not to be unreasonably withheld. Regeneron will
not issue such press release before such time as Immunex and Aventis have fully
executed the Aventis Consent and Agreement. Notwithstanding the above, each
Party shall have the right to disclose in confidence the terms of the Agreement
(a) to parties retained by such Party to perform legal, accounting or similar
services and who have a need to know such terms in order to provide such
services or (b) to prospective assignees, Sublicensees, or
Co-Promoters/Co-Marketers.

6.3 AUTHORIZED DISCLOSURE.

         (a) Each Party may disclose Confidential Information belonging to the
disclosing Party to the extent such disclosure is reasonably necessary in the
following:

             (i) enforcing and/or defending rights or obligations under this
Agreement; and/or

             (ii) complying with any disclosure obligation required by law,
order, rule or regulation of a governmental agency or a court of competent
jurisdiction;

provided however, that the Party required to or intending to disclose the
disclosing Party's Confidential Information under this Section 6.3 shall have
first given prompt notice to the disclosing Party to enable it to seek any
available exemptions from or limitations on such disclosure, and shall
reasonably cooperate in such efforts by the disclosing Party.

                                    ARTICLE 7

                                 INDEMNIFICATION

7.1      INDEMNIFICATION.

          (a) Regeneron shall indemnify, defend and hold harmless Immunex, Amgen
and their respective officers, directors, employees, stockholders, agents and
representatives, (collectively, "Amgen/Immunex Indemnitees") from any and all
Losses arising out of or relating to (i) Regeneron's representations or
warranties set forth in this Agreement being untrue in any material respect when
made; (ii) any material breach or material default by Regeneron of its material
covenants and material obligations under this Agreement and (iii) the research,
development, marketing, design, manufacture, distribution, use and/or sale of
Licensed Product by, on behalf of, or under authority of, Regeneron, its
Affiliates or its Sublicensees. Notwithstanding the foregoing, no Amgen/Immunex
Indemnitee shall be

                                       19
<PAGE>
entitled to indemnification under this Section 7.1 against any Losses arising
out of an Amgen/Immunex Indemnitee's negligence or willful misconduct.

         (b) Amgen and/or Immunex, as appropriate, shall indemnify, defend and
hold harmless Regeneron and its officers, directors, employees, stockholders,
agents and representatives, (collectively, "Regeneron Indemnitees") from any and
all Losses arising out of or relating to (i) Amgen's or Immunex's
representations or warranties set forth in this Agreement being untrue in any
material respect when made; and (ii) any material breach or material default by
Amgen or Immunex of its material covenants and material obligations under this
Agreement. Notwithstanding the foregoing, no Regeneron Indemnitee shall be
entitled to indemnification under this Section 7.1 against any Losses arising
out of a Regeneron Indemnitee's negligence or willful misconduct.

         (c) An indemnified Party shall give prompt notice to the indemnifying
Party of any claim for which the indemnified Party may seek indemnification
under Section 7.1 and, provided that the indemnifying Party is not contesting
the indemnity obligation, shall permit the indemnifying Party to control any
litigation relating to such claim and disposition of any claim; provided
however, that the indemnifying party shall not settle or otherwise resolve any
claim that would materially adversely affect the indemnified Party, without
prior approval by the indemnified Party. The indemnified Party shall cooperate
with the indemnifying Party in its defense of any claim for which
indemnification is sought under this Agreement and shall not settle or offer to
settle any such claim without the indemnifying Party's prior written consent. If
the indemnifying Party elects to defend the claim, it shall not be responsible
for attorneys' fees incurred by the indemnified Party without the indemnifying
Party's consent; provided however, that the indemnified Party shall have the
right to retain its own counsel, at its own expense. The failure by the
indemnified Party to deliver notice to the indemnifying party within a
reasonable time after commencement of any such action, if prejudicial to its
ability to defend such action, shall relieve such indemnifying Party of any
liability to the indemnified Party under this Section 7.1 (to the extent the
failure to be provided such notice shall have been prejudicial to the
indemnifying Party's ability to defend such action), but the omission to deliver
notice to the indemnifying Party will not relieve the indemnifying Party of any
liability that it may have to the indemnified Party other than under this
Section 7.1.

7.2 DAMAGES. Except pursuant to Section 7.1, notwithstanding anything to the
contrary in this Agreement, in no event shall a Party be responsible for any
incidental or consequential damages, including without limitation lost profits
or opportunities, and/or damages in connection with Default and/or termination
of this Agreement, incurred by another Party or its Indemnitees hereunder,
provided however, nothing in this Agreement limits or excludes either Party's
liability for fraud or for death or personal injury caused by such Party's own
negligence.

7.3 INSURANCE. Each Party shall maintain, through self-insurance or
commercially-placed insurance, adequate coverage for the indemnification
obligations set forth herein, consistent with biopharmaceutical industry
practices.

                                       20

<PAGE>
                                    ARTICLE 8

                  REPRESENTATIONS, WARRANTIES AND COVENANTS

8.1   REPRESENTATIONS AND WARRANTIES.  Each Party represents and warrants as
of the Effective Date:

      (a) Corporate Power. It is duly organized and validly existing under the
laws of its state of incorporation and has full corporate power and authority to
enter into this Agreement and to carry out the provisions hereof.

      (b)   Due Authorization.  It is duly authorized to execute and deliver
this Agreement and to perform its obligations hereunder.  The Person
executing this Agreement on its behalf has been duly authorized to do so by
all requisite corporate action.

      (c) Binding Agreement. The execution, delivery and performance of this
Agreement by it does not conflict with any material agreement, instrument or
understanding, oral or written, to which it is a party or by which it may be
bound, nor violate any material law or regulation of any court, governmental
body or administrative or other agency having jurisdiction over it.

      (d)   No Action.  It is aware of no action, suit, or inquiry or
investigation instituted by any Third Party or governmental agency which
questions or threatens the validity of this Agreement.

Amgen represents and warrants that, to the current actual knowledge of the
appropriate members of its legal and licensing departments following due
inquiry, that, except as set forth in Exhibit G, it is not aware of any
agreements with Third Parties that would limit Amgen's right to grant to
Regeneron and its Affiliates a non-exclusive license under the patent and patent
applications identified in Exhibit A to make, have made, use, sell, offer for
sale and import Licensed Products in the Field of Use anywhere in the Territory.
Immunex represents and warrants that, to the current actual knowledge of the
appropriate members of its legal and licensing departments following due
inquiry, that, except as set forth in Exhibit G, it is not aware of any
agreements with Third Parties that would limit Immunex's right to grant to
Regeneron and its Affiliates a non-exclusive license under the patent and patent
applications identified in Exhibit C or Exhibit D to make, have made, use, sell,
offer for sale and import Licensed Products in the Field of Use anywhere in the
Territory.

8.2 NO OTHER WARRANTIES. Other than as set forth in Section 8.1, no Party makes
any other warranties. Each of Immunex and Amgen does not warrant the validity or
enforceability of its respective Patent Rights and makes no representations
whatsoever with regard to the scope of such Patent Rights, or that such Patent
Rights may be exploited without infringing other patents or other intellectual
property rights of Third Parties. Each of Immunex and Amgen MAKES NO WARRANTIES,
EXPRESSED OR IMPLIED, OF THE MERCHANTABILITY OR FITNESS FOR A PARTICULAR PURPOSE
of any subject matter defined by the claims of its respective Patent Rights.
Each of Immunex and Amgen

                                       21
<PAGE>
does not represent that it will commence legal actions of any kind against Third
Parties for infringement of any of its respective Patent Rights.

8.3 COVENANTS. Immunex and Amgen each agree and covenant that neither it, nor
any of its Affiliates, shall grant, transfer or return any right to any Third
Party which would (a) limit or impair the Control of any Amgen Licensed Patent
Right or any Immunex Licensed Patent Right or (b) conflict with the rights
granted to Regeneron hereunder. Immunex further agrees and covenants that it
shall maintain its right to grant Regeneron rights under Section 2.1 or 2.3, as
the case may be, for the following Immunex Patent Rights: (i) the
Immunex-Hoechst Patent Rights, (ii) After-Acquired Patent Rights for which
Regeneron has paid any Pre-Existing Burden Payments, and (iii) Pass Through
Patent Rights for which Regeneron has paid compensation pursuant to Section
2.3(c). Amgen further agrees and covenants that it shall maintain its right to
grant Regeneron rights under Section 2.4, as the case may be, for the following
Amgen Patent Rights: (i) After-Acquired Patent Rights for which Regeneron has
paid any Pre-Existing Burden Payments, and (ii) Pass Through Patent Rights for
which Regeneron has paid compensation pursuant to Section 2.4(c). Immunex
further covenants that it shall use all reasonable efforts to cause the Aventis
Consent and Agreement to be fully executed by Immunex and Aventis as promptly as
possible following the execution of this Agreement.

                                    ARTICLE 9

                                   TERMINATION

9.1 TERM AND TERMINATION. This Agreement shall automatically terminate upon the
expiration of Regeneron's obligation to pay any compensation under Article 3 of
this Agreement, but not earlier than the expiration of the last to expire of the
issued claims of the Immunex Patent Rights and the Amgen Patent Rights,
collectively.

      (a)   Termination by Regeneron. Regeneron shall have the unilateral right
            to terminate this Agreement at any time on thirty (30) days prior
            written notice signed by a duly authorized officer of Regeneron.

      (b)   Termination for Merger not being Consummated. If the Effective Date
            is not on or before July 31, 2003 and the Amended and Restated
            Agreement and Plan of Merger by and among Amgen Inc., AMS
            Acquisition Inc. and Immunex Corporation dated as of December 16,
            2001 has been terminated for any reason, this Agreement shall
            automatically terminate.

9.2 DEFAULT.

      (a) Default by Regeneron of its Obligations to Immunex. In the event
Immunex believes there has been a Default by Regeneron, Immunex may seek a
remedy, including, if appropriate under the circumstances, to terminate the
rights granted under the Immunex Patent Rights by providing written notice to
Regeneron as provided in the definition of Default, and proceeding in accordance
with the provisions set forth below.

                                       22
<PAGE>
                  (i) If after receipt of the written notice required under the
                  definition of Default, Regeneron gives notice to Immunex that
                  it disputes the alleged Default, the Parties will promptly
                  attempt to resolve the dispute pursuant to paragraph 10.11. If
                  the dispute is not resolved under paragraph 10.11 at the
                  expiration of the sixty (60) day cure period referred to in
                  the definition of Default, Immunex may commence legal
                  proceedings (or arbitration if agreed upon) to resolve the
                  dispute whether Regeneron is in Default as alleged and to seek
                  damages and/or any other remedy, including, if appropriate,
                  termination of this Agreement. If it is determined that a
                  Default occurred, the judge (or arbitrator, if appropriate)
                  shall determine what is the appropriate remedy for the Default
                  in question. If no such legal claim or cause of action has
                  been filed (including in arbitration, if appropriate) by
                  Immunex within one-hundred twenty (120) days following the
                  written notice required under the definition of Default,
                  Immunex shall be considered to have waived its right to seek
                  termination or monetary damages with respect to the actions
                  underlying the alleged Default; provided, however, that
                  Immunex shall not be precluded from offering into evidence for
                  any purpose the events giving rise to any previous allegation
                  of Default in any legal proceeding brought following a
                  subsequently alleged Default based on actions other than those
                  underlying the previously alleged Default. The rights granted
                  under this Agreement may not be terminated pending resolution
                  of any legal or arbitration proceedings brought in accordance
                  with this Section 9.2(a)(i), provided Regeneron timely pays
                  all consideration due under the Agreement. Upon the successful
                  termination of such rights pursuant to the procedures set
                  forth in this Section 9.2(a)(i), all rights granted to
                  Regeneron under the Immunex Patent Rights shall revert to
                  Immunex. Moreover, upon the successful termination of such
                  rights, Amgen shall have the immediate right to terminate the
                  rights granted to Regeneron under the Amgen Patent Rights by
                  providing written notice to Regeneron and, upon Regeneron's
                  receipt of such notice, all rights granted to Regeneron under
                  the Amgen Patent Rights shall revert to Amgen.

                  (ii) If the substance of the legal proceeding is whether
                  royalties or other payments are due under the Agreement and/or
                  the amount of such royalty or other payment due, and Regeneron
                  pays the disputed royalty or other amount in order to maintain
                  the Agreement in effect, and final resolution of the legal
                  proceedings determines that such disputed royalty or other
                  payment was not due as alleged, Regeneron shall be entitled to
                  a full refund of any such disputed royalties or other amounts
                  paid, together with a payment charge calculated at an annual
                  rate of three (3) percentage points over the prime rate or
                  successive

                                       23
<PAGE>
                  prime rates (as posted in the Wall Street Journal) during the
                  period such amounts were held by Immunex. If the amount of
                  such charge exceeds the maximum permitted by law, such charge
                  shall be reduced to such maximum.

                  (iii) The process provided for in paragraph 10.11 shall be
                  deemed concluded for purposes of sub-paragraph (i) herein at
                  such point as either Party sends written notice to the other
                  Party or Parties stating that the process has concluded.

                  (iv) For the avoidance of doubt, Immunex may not seek to
                  terminate this Agreement due to a breach of this Agreement by
                  Regeneron other than as a result of Regeneron's failure to
                  perform the specific enumerated obligations identified in the
                  definition of Default. Termination is not the sole and/or
                  exclusive remedy for such Defaults. Nothing in this clause
                  shall be construed as preventing any Party from seeking
                  recovery of monetary damages for breach of the Agreement,
                  whether such breach is a Default or not.

       (b) Default by Regeneron of its Obligations to Amgen. In the event Amgen
believes there has been a Default by Regeneron, Amgen may seek a remedy,
including, if appropriate, to terminate the rights granted under the Amgen
Patent Rights by providing written notice to Regeneron as provided in the
definition of Default, and proceeding in accordance with the provisions set
forth below.

                  (i) If after receipt of the written notice required under the
                  definition of Default, Regeneron gives notice to Amgen that it
                  disputes the alleged Default, the Parties will promptly
                  attempt to resolve the dispute pursuant to paragraph 10.11. If
                  the dispute is not resolved under paragraph 10.11 at the
                  expiration of the sixty (60) day cure period referred to in
                  the definition of Default, Amgen may commence legal
                  proceedings (or arbitration if agreed upon) to resolve the
                  dispute whether Regeneron is in Default as alleged and to seek
                  damages and/or any other remedy, including, if appropriate,
                  termination of this Agreement. If it is determined that a
                  Default occurred, the judge (or arbitrator, if appropriate)
                  shall determine what is the appropriate remedy for the Default
                  in question. If no such legal claim or cause of action has
                  been filed (including in arbitration, if appropriate) by Amgen
                  within one-hundred twenty (120) days following the written
                  notice required under the definition of Default, Amgen shall
                  be considered to have waived its right to seek termination or
                  monetary damages with respect to the actions underlying the
                  alleged Default; provided, however, that Amgen shall not be
                  precluded from offering into evidence for any purpose the
                  events giving rise to any previous allegation of Default in
                  any legal proceeding brought following a

                                       24
<PAGE>
                  subsequently alleged Default based on actions other than those
                  underlying the previously alleged Default. The rights granted
                  under this Agreement may not be terminated pending resolution
                  of any legal or arbitration proceedings brought in accordance
                  with this Section 9.2(a)(i), provided Regeneron timely pays
                  all consideration due under the Agreement. Upon the successful
                  termination of such rights pursuant to the procedures set
                  forth in this Section 9.1(b)(i), all rights granted to
                  Regeneron under the Amgen Patent Rights shall revert to Amgen.
                  Moreover, upon the successful termination of such rights,
                  Immunex shall have the immediate right to terminate the rights
                  granted to Regeneron under the Immunex Patent Rights by
                  providing written notice to Regeneron and, upon Regeneron's
                  receipt of such notice, all rights granted to Regeneron under
                  the Immunex Patent Rights shall revert to Immunex.

                  (ii) If the substance of the legal proceeding is whether
                  royalties or other payments are due under the Agreement and/or
                  the amount of such royalty or other payments due, and
                  Regeneron pays the disputed royalty or other amount in order
                  to maintain the Agreement in effect, and final resolution of
                  the legal proceedings determines that such disputed royalty or
                  other payment was not due as alleged, Regeneron shall be
                  entitled to a full refund of any such disputed royalties or
                  other amounts paid, together with a payment charge calculated
                  at an annual rate of three (3) percentage points over the
                  prime rate or successive prime rates (as posted in the Wall
                  Street Journal) during the period such amounts were held by
                  Amgen. If the amount of such charge exceeds the maximum
                  permitted by law, such charge shall be reduced to such
                  maximum.

                  (iii) The process provided for in paragraph 10.11 shall be
                  deemed concluded for purposes of sub-paragraph (i) herein at
                  such point as either Party sends written notice to the other
                  Party or Parties stating that the process has concluded.

                  (iv) For the avoidance of doubt, Amgen may not seek to
                  terminate this Agreement due to a breach of this Agreement by
                  Regeneron other than as a result of Regeneron's failure to
                  perform the specific enumerated obligations identified in the
                  definition of Default. Termination is not the sole and/or
                  exclusive remedy for such Defaults. Nothing in this clause
                  shall be construed as preventing any Party from seeking
                  recovery of monetary damages for breach of the Agreement,
                  whether such breach is a Default or not.

9.3 INSOLVENCY OR BANKRUPTCY. All rights and licenses granted under or pursuant
to this Agreement to Regeneron are, and shall otherwise be deemed to be, for
purposes of Section 365(n) of the United States Bankruptcy Code, licenses of
rights to "intellectual property" as

                                       25
<PAGE>
defined under Section 101 of the United States Bankruptcy Code. The Parties
agree that Regeneron shall retain all licenses granted to it hereunder and may
fully exercise all of its rights and elections under the United States
Bankruptcy Code, subject to payment to Immunex or Amgen, as appropriate, of any
compensation due pursuant to Article 3.

9.4 ACCRUED RIGHTS, SURVIVING OBLIGATIONS. Termination, relinquishment or
expiration of this Agreement for any reason shall be without prejudice to any
rights which shall have accrued to the benefit of either Party prior to such
termination, relinquishment or expiration.

9.5 EFFECTS OF TERMINATION. Upon termination or expiration of this Agreement,

      (a) The following provisions shall remain in full force and effect:
Article 1, Article 4 (as provided therein), Article 6 (as provided therein),
Article 7, Section 9.4, Section 9.5 and Article 10.

      (b) Regeneron, its Affiliates and its Sublicensees shall thereupon have
the right to sell that amount of any such Licensed Product they then have in
their possession or control, provided however, that with respect to any such
Licensed Product for which compensation is due under Article 3, Regeneron shall
pay the amounts due thereunder at the time provided for.

      (c) Each Party will upon request promptly return all copies of any
documents, samples or other physical embodiments of the Confidential Information
to the originating Party except each Party may retain one copy in its corporate
files (or with the Independent Accountant) for reference.

      (d) No Party hereto shall be released from any liability which, at the
time of such termination, shall have already accrued or which shall be
attributable to a period prior to such termination nor preclude a Party from
pursuing any rights and remedies it may have hereunder or at law or in equity
with respect to any breach of this Agreement.

      (e) Except as specifically provided herein, all other rights and
obligations under this Agreement shall terminate upon termination or expiration
of this Agreement, and Regeneron shall no longer be a licensee pursuant to this
Agreement.

                                   ARTICLE 10

                            MISCELLANEOUS PROVISIONS

10.1 ASSIGNMENT. Neither this Agreement nor any interest hereunder shall be
assignable by any Party without the prior written consent of the other Parties;
provided however, that a Party may assign this Agreement and all of its rights
and obligations hereunder, without such consent, (i) to any Affiliate, provided
such interest shall be retransferred to the relevant Party if such entity ceases
to be an Affiliate of such Party, and provided further that the assigning Party
shall remain responsible for acts and omissions of (including the performance of
this Agreement by) its Affiliate or (ii) to an entity which acquires all or
substantially all of the

                                       26
<PAGE>
business to which this agreement pertains, whether by merger, consolidation,
reorganization, acquisition, sale, license or otherwise. This Agreement shall be
binding upon the successors and permitted assigns of a Party, and the name of a
Party appearing herein shall be deemed to include the names of such Party's
successors and permitted assigns to the extent necessary to carry out the intent
of this Agreement. For the avoidance of doubt, Immunex may assign this entire
Agreement and its interests hereunder to Amgen or an Affiliate of Amgen at any
time after the closing of the acquisition of Immunex by Amgen; and, upon such
assignment, reference to "Immunex", "Immunex and Amgen", "Immunex or Amgen" and
"Immunex and/or Amgen", in each instance, shall be deemed reference to "Amgen"
alone. Any assignment not in accordance with this Section 10.1 shall be void.

10.2 COSTS. Each Party shall bear its own legal costs and expenses arising out
of the negotiation, execution and delivery of this Agreement.

10.3 FORCE MAJEURE. No Party shall be liable to the other for Losses, nor shall
have any right to terminate this Agreement for any default or delay attributable
to any Force Majeure, if the Party affected shall give prompt notice of any such
cause to the other Parties. The Party giving such notice shall thereupon be
excused from such of its obligations hereunder as it is thereby disabled from
performing for so long as it is so disabled, provided however, that such
affected Party commences and continues to take reasonable and diligent actions
to cure such cause.

10.4 NOTICES. All notices and other communications required by this Agreement
shall be in writing and shall be deemed given if delivered personally or by
facsimile transmission (receipt verified), mailed by registered or certified
mail (return receipt requested), postage prepaid, or sent by express courier
service, to the Parties at the following addresses (or at such other address for
a Party as shall be specified by like notice, provided however, that notices of
a change of address shall be effective only upon receipt thereof):

If to Regeneron, addressed to:

Regeneron Pharmaceuticals, Inc.
Attention: President
777 Old Saw Mill River Road
Tarrytown, NY 10591-6707
Facsimile: [******************]

With a copy to: Vice President and General Counsel
Facsimile: [*******************]

If to Immunex, addressed to:

Immunex Corporation
51 University Street
Seattle, WA 98101
Facsimile: [*****************]

                                       27
<PAGE>
With a copy to: General Counsel
Facsimile: [*****************]

If to Amgen, addressed to:

Amgen Inc.
One Amgen Center Drive
Thousand Oaks, California USA 91320-1799
Attention: Corporate Secretary
Facsimile: [*****************]

With a copy to: Vice President, Product Licensing
Facsimile: [*****************]

10.5 AMENDMENT. No amendment, modification or supplement of any provision of
this Agreement shall be valid or effective unless made in writing and signed by
a duly authorized officer of each Party.

10.6 WAIVER. Except as set forth herein, no provision of the Agreement shall be
waived by any act, omission or knowledge of any Party or its agents or
employees, except by an instrument in writing expressly waiving such provision
and signed by a duly authorized officer of the waiving Party.

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

10.8 DESCRIPTIVE HEADINGS. The descriptive headings of this Agreement (including
the headings in any exhibits hereto) are for convenience only, and shall be of
no force or effect in construing or interpreting any of the provisions of this
Agreement.

10.9 GOVERNING LAW. This Agreement shall be governed and interpreted in all
respects under the substantive laws of the State of Delaware as applied to
agreements executed and performed entirely in the State of Delaware by residents
of the State of Delaware, without giving effect to those provisions governing
conflicts of law. The Parties consent to the exclusive jurisdiction of the
Delaware Courts for all matters arising out of or relating to this Agreement,
and further consent that any process, notice of motion or other application to
either such court or judge thereof may be served outside of Wilmington, Delaware
by registered or certified mail or by personal service, provided that a
reasonable time for appearance is allowed. Any dispute, controversy or claim
relating to the scope, validity, enforceability or infringement of Amgen Patent
Rights and/or Immunex Patent Rights in a country shall be governed by the laws
of that country.

10.10 SEVERABILITY. Whenever possible, each provision of this Agreement shall be
interpreted in such manner as to be effective and valid under applicable law,
but if any provision of this Agreement is held to be prohibited by or invalid
under applicable law, such

                                       28
<PAGE>
provision shall be ineffective only to the extent of such prohibition or
invalidity, without invalidating the remainder of this Agreement. The Parties
shall make a good faith effort to replace the invalid or unenforceable provision
with a valid one which in its economic effect is most consistent with the
objectives contemplated by the Parties as evidenced by the terms and conditions
of this Agreement when entering into such invalid or unenforceable one.
Invalidity, non-enforceability or expiration of any or all of the Amgen Patent
Rights or Immunex Patent Rights shall not affect Regeneron's license rights in
and to the remaining Amgen Patent Rights and Immunex Patent Rights.

10.11 DISPUTE RESOLUTION. The Parties agree that in the event of a dispute
between and/or among them arising from, concerning or in any way relating to
this Agreement, the Parties shall undertake good faith efforts to resolve any
such dispute in good faith. In the event the Parties shall be unable to resolve
any such dispute, the matter shall be first referred to the general counsel for
each Party for further review and resolution and, if necessary, then to the
chief executive officer of each Party. If after such efforts the Parties are
unable to resolve such dispute, a Party may seek any legal or equitable remedy
available to it.

10.12 INDEPENDENT CONTRACTORS. The relationship among the Parties created by
this Agreement is one of independent contractors, and no Party shall have the
power or authority to bind or obligate the other except as expressly set forth
in this Agreement.

10.13 USE OF NAME. In addition to being subject to Article 6, no right, express
or implied, is granted to a Party by this Agreement to use in any manner any
trademark or trade name of another Party or its Affiliates, including the names
"Amgen", "Immunex" and "Regeneron", without the prior written consent of the
owning Party.

10.14 FURTHER ACTIONS. Each Party agrees to execute, acknowledge and deliver
such further instruments, and to do all such other acts, as may be necessary or
appropriate in order to carry out the purposes and intent of this Agreement.

10.15 NO ADMISSION. This Agreement shall not be construed as an admission of any
Party that any patent is valid, infringed, enforceable, or invalid, not
infringed or not enforceable. This Agreement may not be offered into evidence or
referred to by any Party in any action against another Party for patent
infringement as evidence of an admission respecting infringement or validity of
any patent. Other than in connection with the enforcement of this Agreement,
this Agreement may not be offered into evidence for the purpose of establishing
appropriate damages for infringement of any Patent Rights covered by this
Agreement.

10.16 [*********************************]

                                      * * *

                  [remainder of page intentionally left blank]

                                      * * *

                                       29
<PAGE>
10.17 ENTIRE AGREEMENT OF THE PARTIES. This Agreement (including all Exhibits
attached hereto, which are incorporated herein by reference) shall constitute
and contain the complete, final and exclusive understanding and agreement of the
Parties and cancels and supersedes any and all prior negotiations,
correspondence, representations, promises, understandings and agreements,
whether oral or written, between the Parties respecting the subject matter
thereof.

      IN WITNESS WHEREOF, the Parties hereto have executed this Agreement in
duplicate by their respective duly authorized officers.

REGENERON PHARMACEUTICALS, INC.

/s/ Stuart Kolinski
------------------------------------------
By: Stuart Kolinski
    --------------------------------------
Title: General Counsel
       -----------------------------------
Date:  June 26, 2002
       -----------------------------------

IMMUNEX CORPORATION                        AMGEN INC.

/s/ Edward V. Fritzky                      /s/ Scott J. Foraker
---------------------------------------    -------------------------------------
By: Edward V. Fritzky                      By: Scott J. Foraker
    -----------------------------------    -------------------------------------
Title: Chairman and CEO                    Title: Vice President Licensing
       --------------------------------           ------------------------------
Date:  June 26, 2002                       Date:  June 26, 2002
       --------------------------------           ------------------------------

                                       30
<PAGE>
                                    EXHIBIT A

                          Amgen Licensed Patent Rights

                 [********************************************]

                                      F-1
<PAGE>
                                    EXHIBIT B

              Consent and Agreement Modifying Receptor Agreement

               [**********************************************]

                                      F-2
<PAGE>
                                    EXHIBIT C

                          Immunex-Hoechst Patent Rights

               [*********************************************]

                                      F-3
<PAGE>
                                    EXHIBIT D

                           Immunex IL-1r Patent Rights

                [********************************************]

                                      F-4
<PAGE>
                                    EXHIBIT E

                 Payment Terms for After-Acquired Patent Rights

Pursuant to Section 2.3(b) and 2.4(b), should Regeneron elect to have
After-Acquired Patent Rights included within the Immunex Patent Rights or the
Amgen Patent Rights, respectively, Regeneron must pay the consideration set
forth herein:

[****************************************************************************]

                                      F-5
<PAGE>
                                    EXHIBIT F

                                  PRESS RELEASE

    REGENERON GRANTED LICENSE BY AMGEN AND IMMUNEX TO INTERLEUKIN-1 INHIBITOR
                                     PATENTS

Tarrytown, NY (June XX, 2002) -- Regeneron Pharmaceuticals (Nasdaq: REGN)
announced that it has entered into an agreement with Amgen Inc. and Immunex
Corporation for a non-exclusive license to certain intellectual property rights
which may be used in the development and commercialization of Regeneron's
interleukin-1 (IL1) Trap. Amgen and Immunex agreed to grant the license to
Regeneron in connection with Amgen's pending acquisition of Immunex, which is
currently under review by the Federal Trade Commission. The license to Regeneron
becomes effective upon the completion of the acquisition.

This license follows two other licensing arrangements under which Regeneron
obtained rights to practice intellectual property for potential use in its IL1
Trap program. The Company gained nonexclusive rights to patents owned by
ZymoGenetics, Inc. covering immunoglobulin-fusion proteins. In addition, [ ]

"The IL1 Trap demonstrated clinical activity in patients with rheumatoid
arthritis in a Phase I trial and a Phase II trial is scheduled to begin
shortly," noted Stuart Kolinski, Regeneron's Vice President and General Counsel.
"Regeneron was able to secure these three licenses to intellectual property
rights, which enhance our existing patent portfolio for the IL1 Trap, in
exchange for total royalties in the mid-single digits.

This news release discusses historical information and includes forward-looking
statements about Regeneron and its products, programs, finances, and business,
all of which involve a number of risks and uncertainties, such as risks
associated with preclinical and clinical development of drugs and biologics,
determinations by regulatory and administrative governmental authorities,
competitive factors, technological developments, the availability and cost of
capital, the costs of developing, producing,

                                      F-6
<PAGE>
and selling products, the potential for any collaboration agreement to be
canceled or to terminate without any product success, and other material risks.
A more complete description of these risks can be found in Regeneron's filings
with the United States Securities and Exchange Commission, including its Form
10-K for the year ended December 31, 2001. Regeneron does not undertake any
obligation to update publicly any forward-looking statement, whether as a result
of new information, future events, or otherwise, unless required by law.

Regeneron is a biopharmaceutical company that discovers, develops, and intends
to commercialize therapeutic medicines for the treatment of serious medical
conditions. Regeneron has therapeutic candidates in clinical trials for the
potential treatment of obesity, rheumatoid arthritis, and cancer, and has
preclinical programs in asthma, allergies, and other diseases and disorders.
Regeneron's platform technologies include Targeted Genomics(TM),
Functionomics(TM), and Designer Protein Therapeutics(TM).

                                       ###

Contact:          Charles Poole
                  Vice President, Investor Relations
                  Regeneron Pharmaceuticals, Inc.
                  charles.poole@regn.com
                  (914) 345-7641

Media Contact:    Jeanne Abi-Nader
                  Vice President
                  Robinson, Lerer, Montgomery
                  jabi-nader@rlmnet.com
                  (212) 484-7954

Additional information about Regeneron and recent news releases are available on
Regeneron's Worldwide Web Home Page at www.regn.com. Fax copies of news releases
can be obtained from Regeneron's News-on-Demand Service by dialing (800)
311-0841.

                                      F-7
<PAGE>
                                    EXHIBIT G

              SCHEDULE OF LIMITATIONS OF LICENSED PATENT RIGHTS

[********************************************]

                                      F-8

Source: [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00041-of-00352.parquet"}, [{"source": "alea-institute/alea-institute/kl3m-data-edgar-agreements/train-00041-of-00352.parquet"}]]