Document:

exv10w3

 

EXHIBIT 10.3

Summary of Terms of

Warrants Issued to

The Elevation Fund LLC

as of June 30, 2006

In connection with a Loan Agreement dated April 1, 2005 and an Extension Agreement dated July 18,
2005, The Fashion House Holdings, Inc. (the “Company”) previously has issued to The
Elevation Fund LLC warrants (the “Previous Warrants”) to purchase an aggregate of 1,662,500
shares of the Company’s common stock with an exercise price of $0.80 per share. The Previous
Warrants are no longer deemed outstanding, and, as of June 30, 2006, warrants (the “New
Warrants”) to purchase 1,212,500 shares of common stock of the Company are issued and
outstanding to The Elevation Fund LLC. The exercise price of the New Warrants is $0.60 per share
and the New Warrants expire on August 19, 2015.

In connection with the issuance of the New Warrants, the following liquidated damages clause has
been eliminated:

	 	•	 	Additional Warrants, as defined in the Loan Agreement dated April 1,
2005, which were accruing at a rate equal to 75,000 warrants for each
30 day period subsequent to November 3, 2005 that the Company’s
registration statement had not been filed and an additional 75,000
warrants for each 30 day period subsequent to February 19, 2006.

In connection with the issuance of the New Warrants and the elimination of the
above damages clause, the Company is no longer obligated to issue additional
warrants to The Elevation Fund LLC.<PAGE>

                                                                   EXHIBIT 10.11

                                                                   REDACTED COPY

                       COLLABORATION AND LICENSE AGREEMENT

                                 by and between

                                      WYETH
                acting through its Wyeth Pharmaceuticals Division

                                       and

                          TRUBION PHARMACEUTICALS, INC.

                                December 19, 2005

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                                                                   REDACTED COPY

                                TABLE OF CONTENTS

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1.  DEFINITIONS..........................................................     1
2.  LICENSES.............................................................    16
    2.1   Licenses to Wyeth..............................................    16
          2.1.1  Exclusive Licenses......................................    16
          2.1.2  Retained Rights of Trubion..............................    17
    2.2   License to Trubion.............................................    17
    2.3   Exclusivity....................................................    17
          2.3.1  CD20 Product Exclusivity................................    17
          2.3.2  ***.....................................................    18
          2.3.3  Limitations.............................................    18
    2.4   Sublicensing...................................................    18
    2.5   Direct Licenses to Affiliates..................................    19
    2.6   Right of Reference.............................................    20
    2.7   Section 365(n) of Bankruptcy Code..............................    20
    2.8   No Implied Rights..............................................    21

3.  RESEARCH PROGRAM.....................................................    21
    3.1   Scope and Conduct of the Research Program......................    21
    3.2   Designation of Targets.........................................    21
          3.2.1  Target Candidates.......................................    22
          3.2.2  Released Targets........................................    23
          3.2.3  Wyeth Targets...........................................    23
          3.2.4  Excluded Targets........................................    24
    3.3   Term and Termination of the Research Program...................    27
          3.3.1  Research Term...........................................    27
          3.3.2  Termination of Research Program by Wyeth................    27
    3.4   Joint Research Committee.......................................    27
          3.4.1  Composition.............................................    27
          3.4.2  Responsibilities........................................    27
          3.4.3  Meetings................................................    28
          3.4.4  Voting..................................................    28
          3.4.5  Dispute Resolution......................................    28
          3.4.6  Minutes.................................................    28
    3.5   Research Plan..................................................    28
    3.6   Funding of the Research Program................................    29
          3.6.1  Research Funding........................................    29
          3.6.2  Reimbursement Payments..................................    30
          3.6.3  Records and Audits......................................    30
    3.7   Data and Deliverables..........................................    31
    3.8   Alliance Managers..............................................    31

4.  PRODUCT DEVELOPMENT, MANUFACTURING, COMMERCIALIZATION AND
    REGULATORY MATTERS...................................................    32
    4.1   Product Development............................................    32
    4.2   Transfer of Product Data and Filings...........................    32
    4.3   Regulatory Approvals...........................................    33
    4.4   Regulatory Reporting...........................................    33
    4.5   Progress Reports...............................................    34
    4.6   CD20 Product Development.......................................    35
    4.7   Joint Development Committee....................................    36
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    4.8   Joint Project Team; Development Plan...........................    36
    4.9   Manufacturing..................................................    36
    4.10  Commercialization..............................................    37
    4.11  Co-Promotion Option............................................    38
    4.12  Co-Promotion Committee.........................................    38
    4.13  Co-Branding....................................................    38
    4.14  Marking........................................................    38

5.  CONSIDERATION........................................................    38
    5.1   Initial Research and Development Expense Payment...............    39
    5.2   Equity.........................................................    39
    5.3   Additional Research and Development Expense Payments...........    39
    5.4   Royalties......................................................    39
          5.4.1  Product Royalties.......................................    39
          5.4.2  CD20 Product Royalties..................................    39
          5.4.3  ***.....................................................    42
          5.4.4  Other Product Royalties.................................    44
          5.4.5  Expiration of Royalty Period............................    45
          5.4.6  Royalty Adjustments.....................................    45
    5.5   Reports and Payments...........................................    46
          5.5.1  Cumulative Royalties....................................    46
          5.5.2  Royalty Statements and Payments.........................    46
          5.5.3  Taxes and Withholding...................................    47
          5.5.4  Currency................................................    47
          5.5.5  Additional Provisions Relating to Royalties.............    47
          5.5.6  Interest on Past Due Payments...........................    48
    5.6   Maintenance of Records; Audits.................................    48
          5.6.1  Record Keeping..........................................    48
          5.6.2  Audits..................................................    49
          5.6.3  Underpayments/Overpayments..............................    49
          5.6.4  Confidentiality.........................................    49

6.  INTELLECTUAL PROPERTY................................................    49
    6.1   Inventions; Joint Patent Committee.............................    49
          6.1.1  Ownership and Inventorship..............................    50
          6.1.2  SMIP Improvements.......................................    50
          6.1.3  Joint Patent Committee..................................    51
    6.2   Patent Rights..................................................    52
          6.2.1  Filing, Prosecution and Maintenance of Patent Rights....    52
          6.2.2  Enforcement of Patent Rights............................    59
          6.2.3  Infringement and Third Party Licenses...................    61
          6.2.4  Patent Certifications...................................    64
          6.2.5  Patent Term Restoration.................................    64
    6.3   Trademarks.....................................................    64

7.  CONFIDENTIALITY......................................................    64
    7.1   Confidentiality................................................    64
    7.2   Authorized Disclosure and Use..................................    65
          7.2.1  Disclosure..............................................    65
          7.2.2  Use.....................................................    66
    7.3   SEC Filings....................................................    66
    7.4   Public Announcements; Publications.............................    66
          7.4.1  Coordination............................................    67
          7.4.2  Announcements...........................................    67
          7.4.3  Publications............................................    67
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8.  REPRESENTATIONS AND WARRANTIES.......................................    68
    8.1   Representations and Warranties of Each Party...................    68
    8.2   Additional Representations and Warranties of Trubion...........    68
    8.3   Mutual Covenant................................................    70
    8.4   Additional Covenants of Trubion................................    70
    8.5   Representation by Legal Counsel................................    70
    8.6   No Inconsistent Agreements.....................................    70
    8.7   Disclaimer.....................................................    70

9.  GOVERNMENT APPROVALS; TERM AND TERMINATION...........................    70
    9.1   HSR Filing.....................................................    70
    9.2   Other Government Approvals.....................................    71
    9.3   Term...........................................................    71
    9.4   Termination Upon HSR Denial....................................    71
    9.5   Material Breach................................................    71
    9.6   Termination by Wyeth...........................................    72
          9.6.1  Termination Without Cause...............................    72
          9.6.2  Termination for a Material Safety or Regulatory Issue...    72
    9.7   Effects of Termination.........................................    73
          9.7.1  Effect of Termination by Wyeth for Cause................    73
          9.7.2  Effect of Termination by Trubion for Cause..............    76
          9.7.3  Effect of Termination by Wyeth Without Cause............    79
          9.7.4  Effect of Termination by Wyeth for a Material
                 Safety or Regulatory Issue..............................    82
          9.7.5  Post-Termination Rights to Wyeth Technology and
                 Trubion Technology......................................    83
          9.7.6  Post-Termination Licenses to Wyeth Technology...........    83
          9.7.7  Post-Termination Transfer of Product Data and Filings
                 and Existing Trademarks.................................    83
          9.7.8  Manufacturing of Licensed Products After Termination....    84
          9.7.9  Post-Termination Disposition of Inventories of
                 Licensed Products.......................................    85
          9.7.10 Continuation of Rights and Licenses Under Sections
                 6.1.1 and 6.1.2.........................................    85
          9.7.11 Continuation of Other Rights and Obligations............    85
    9.8   Modification of Agreement Terms by Wyeth.......................    85
    9.9   Survival of Certain Obligations................................    86
    9.10  Change of Control..............................................    86
          9.10.1 Definition..............................................    86
          9.10.2 Change of Control of Wyeth..............................    87
          9.10.3 Change of Control of Trubion............................    89

10. INDEMNIFICATION AND INSURANCE........................................    89
    10.1  Indemnification by Wyeth.......................................    89
    10.2  Indemnification by Trubion.....................................    90
    10.3  Procedure......................................................    90
    10.4  Insurance......................................................    91

11. DISPUTE RESOLUTION...................................................    91
    11.1  General........................................................    91
    11.2  Failure of Executive Officers to Resolve Dispute...............    92
    11.3  Disclaimer of Consequential and Punitive Damages...............    92

12. MISCELLANEOUS........................................................    92
    12.1  Periodic Executive Meetings....................................    92
    12.2  Assignment.....................................................    92
    12.3  Further Actions................................................    93
    12.4  Force Majeure..................................................    93
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    12.5  Non-Solicitation...............................................    93
    12.6  Correspondence and Notices.....................................    93
          12.6.1 Ordinary Notices........................................    93
          12.6.2 Extraordinary Notices...................................    94
    12.7  Amendment......................................................    95
    12.8  Waiver.........................................................    95
    12.9  Severability...................................................    95
    12.10 Descriptive Headings...........................................    95
    12.11 Governing Law..................................................    95
    12.12 Entire Agreement of the Parties................................    95
    12.13 Independent Contractors........................................    96
    12.14 Counterparts...................................................    96
</TABLE>

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                                                                   REDACTED COPY

                                    EXHIBITS

Exhibit 1.122  - TRU-015
Exhibit 1.129  - Trubion Patent Rights
Exhibit 1.132  - Trubion Third Party Agreements
Exhibit 3.2.1  - Trubion's "Milestone One"
Exhibit 3.2.4  - Excluded Targets
Exhibit 4.4    - Adverse Event Reporting Procedures
Exhibit 5.2A   - Stock Purchase Agreement
Exhibit 5.2B   - Amendment to Investor Rights Agreement
Exhibit 5.3    - Additional Research and Development Expense Payments
Exhibit 8.2(d) - Third Party Rights
Exhibit 8.2(e) - Government Funding Agreements

<PAGE>

                                                                  EXECUTION COPY

                       COLLABORATION AND LICENSE AGREEMENT

     This Collaboration and License Agreement (the "Agreement") is entered into
as of December 19, 2005 (the "Signing Date"), by and between Wyeth, together
with its Affiliates (as defined below), acting through its Wyeth Pharmaceuticals
Division, a corporation organized and existing under the laws of the State of
Delaware and having a place of business at 500 Arcola Road, Collegeville,
Pennsylvania 19426 (collectively, "Wyeth") and Trubion Pharmaceuticals, Inc.,
together with its Affiliates (as defined below), a corporation organized and
existing under the laws of the State of Delaware and having a principal place of
business at 2401 4th Avenue, Suite 1050, Seattle, Washington 98121
(collectively, "Trubion"). Wyeth and Trubion may each be referred to herein
individually as a "Party" and collectively as the "Parties".

     WHEREAS, Wyeth is engaged in the research, development and
commercialization of pharmaceutical and health care products;

     WHEREAS, as of the Signing Date, Trubion has developed certain SMIPs (as
defined below) and CD20 Products (as defined below), as well as certain Patent
Rights (as defined below) and Know-How (as defined below) pertaining to
Trubion's SMIP technology platform;

     WHEREAS, Wyeth and Trubion desire to collaborate to discover, research and
develop, and Wyeth desires to research, develop, manufacture and commercialize,
Licensed Products (as defined below) as provided herein; and

     WHEREAS, Wyeth desires to obtain from Trubion, and Trubion desires to grant
to Wyeth, certain exclusive rights so that Wyeth may develop, manufacture and
commercialize such Licensed Products, as provided herein.

     NOW THEREFORE, in consideration of the mutual promises and covenants set
forth below and other good and valuable consideration, the receipt and
sufficiency of which is hereby acknowledged, the Parties hereby agree as
follows:

1.   DEFINITIONS.

     1.1. "ADDITIONAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENT" shall have the
          meaning set forth in Section 5.3 hereof.

     1.2. "ADDITIONAL THIRD PARTY LICENSES" shall have the meaning set forth in
          Section 6.2.3(a) hereof.

     1.3. "AFFILIATE(S)" shall mean, with respect to any Person, any other
          Person which controls, is controlled by or is under common control
          with such Person. A Person shall be regarded as in control of another
          entity if it owns or controls at least fifty percent (50%) of the
          equity securities of the subject entity entitled to vote in the
          election of directors (or, in the case of an entity that is not a
          corporation, for the election of the corresponding managing

<PAGE>

                                                                   REDACTED COPY

          authority); provided, however, that the term "Affiliate" shall not
          include subsidiaries or other entities in which a Party or its
          Affiliates owns a majority of the ordinary voting power necessary to
          elect a majority of the board of directors or other governing board,
          but is restricted from electing such majority by contract or
          otherwise, until such time as such restrictions are no longer in
          effect.

     1.4. "AGREEMENT" shall have the meaning set forth in the preamble hereof.

     1.5. "BANKRUPTCY CODE" shall have the meaning set forth in Section 2.7
          hereof.

     1.6. "BLA" shall have the meaning set forth in Section 1.100 hereof.

     1.7. "CALENDAR QUARTER" shall mean the respective periods of three (3)
          consecutive calendar months ending on March 31, June 30, September 30
          or December 31, for so long as this Agreement is in effect.

     1.8. "CATEGORY 1 COVERED SMIP IMPROVEMENT" shall have the meaning set forth
          in Section 6.1.3(b) hereof.

     1.9. "CATEGORY 2 COVERED SMIP IMPROVEMENT" shall have the meaning set forth
          in Section 6.1.3(b) hereof.

     1.10. "CD20 ANTIGEN" shall mean the human protein antigen that is known as
           CD20, and identified as a full length CD20 protein antigen in GenBank
           and identified by ***, and any other protein that *** as the
           foregoing.

     1.11. "CD20 EFFECTIVE ROYALTY RATE" shall have the meaning set forth in
           Section 5.4.2(a) hereof.

     1.12. "CD20 PRODUCT" shall mean any TRU-015 Product and/or Follow-On CD20
           Product (as the context requires).

     1.13. "CELL LINES" shall mean the cell lines and any other expression
           systems that produce or express any SMIP.

     1.14. "CHANGE OF CONTROL" shall have the meaning set forth in Section
           9.10.1 hereof.

     1.15. "CLINICAL STUDY SUPPLIES" shall have the meaning set forth in Section
           4.9 hereof.

     1.16. "COMBINATION PRODUCT" shall mean any product containing as active
           ingredients both (a) a Product and (b) one or more other
           pharmaceutically active compounds or substances.

     1.17. "COMBINATION SALE" shall have the meaning set forth in Section 1.76
           hereof.

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     1.18. "COMMERCIALIZATION" OR "COMMERCIALIZE" shall mean activities directed
          to marketing, promoting, distributing, importing or selling a product.
          Commercialization shall not include any activities related to
          Manufacturing or Development.

     1.19. "COMMERCIALLY REASONABLE EFFORTS" shall mean, with respect to the
          efforts to be expended by any Party with respect to any objective,
          those reasonable, diligent, good faith efforts to accomplish such
          objective as such Party would normally use to accomplish a similar
          objective under similar circumstances. With respect to any objective
          relating to the Development and/or Commercialization of a Licensed
          Product by any Party, "Commercially Reasonable Efforts" shall mean
          those efforts and resources normally used by such Party with respect
          to a product owned or controlled by such Party, or to which such Party
          has similar rights, which product is of similar market potential and
          is at a similar stage in its development or life as is such Licensed
          Product, taking into account issues of safety, efficacy, product
          profile, the competitiveness of the marketplace, the proprietary
          position of the Licensed Product, the regulatory structure involved,
          profitability of the Licensed Product and other relevant commercial
          factors. A "COMMERCIALLY REASONABLE" action or decision of a Party
          refers in this Agreement to an action or decision taken or made by
          such Party using its Commercially Reasonable Efforts.

     1.20. "CONFIDENTIAL INFORMATION" of a Party shall mean all Know-How or
          other information, including, without limitation, proprietary
          information and materials (whether or not patentable) regarding such
          Party's technology, products, business information or objectives, that
          is communicated in any way or form by the Disclosing Party to the
          Receiving Party, either prior to or after the Effective Date of this
          Agreement, and whether or not such Know-How or other information is
          identified as confidential at the time of disclosure; provided that,
          information not identified as confidential by the Disclosing Party
          shall be deemed to be Confidential Information of the Disclosing Party
          if the Receiving Party knows, or should have had a reasonable
          expectation, that the information communicated by the Disclosing Party
          is Confidential Information of the Disclosing Party. The terms and
          conditions of this Agreement shall be considered Confidential
          Information of both Parties.

     1.21. "CONJUGATE(S)" shall mean SMIP(s) fused genetically or linked, either
          directly or through a linker molecule, with any biological,
          cytostatic, cytotoxic or radioactive agent.

     1.22. "CONTROL" OR "CONTROLLED" shall mean with respect to any (a) item of
          information, including, without limitation, Know-How, or (b)
          intellectual property right, the possession (whether by ownership or
          license, other than pursuant to this Agreement) by a Party of the
          ability to grant to the other Party a license or to extend other
          rights as provided herein, under such item

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          or right without violating the terms of any agreement or other
          arrangements with any Third Party.

     1.23. "CO-PROMOTION" shall mean the joint promotion of a CD20 Product in
          the United States by both Parties and/or their respective Affiliates
          under the same CD20 Product Trademark(s). "CO-PROMOTE," when used as a
          verb, shall mean to engage in such Co-Promotion.

     1.24. "CO-PROMOTION PERIOD" shall have the meaning set forth in Section
          4.11 hereof.

     1.25. "COVERED SMIP IMPROVEMENT" shall have the meaning set forth in
          Section 6.1.2 hereof.

     1.26. "DEPOSITED PROTEIN" shall have the meaning set forth in Section 1.45
          hereof.

     1.27. "DESIGNATED TARGET(S)" shall have the meaning set forth in Section
          9.8 hereof.

     1.28. "DEVELOPMENT" OR "DEVELOP" shall mean non-clinical and clinical drug
          development activities pertaining to a product, including, without
          limitation, toxicology, pharmacology, test method development and
          stability testing, process development, formulation development,
          delivery system development, quality assurance and quality control
          development, statistical analysis, clinical studies (including pre-
          and post-approval studies), regulatory affairs, pharmacovigilance and
          Regulatory Approval and clinical study regulatory activities
          (including regulatory activities directed to obtaining pricing and
          reimbursement approvals).

     1.29. "DEVELOPMENT PLAN" shall mean the written plan for the Development of
          CD20 Products described in Section 4.8 hereof.

     1.30. "DISCLOSING PARTY" shall have the meaning set forth in Section 7.1
          hereof.

     1.31. "EFFECTIVE DATE" shall mean the later to occur of (a) the Signing
          Date and (b) the HSR Clearance Date.

     1.32. "EXCHANGE ACT" shall mean the Securities Exchange Act of 1934, as
          amended.

     1.33. "EXCLUDED TARGET(S)" shall mean the Target(s) described in Section
          3.2.4 hereof as Excluded Target(s).

     1.34. "EXCLUSIVITY COVENANTS" shall have the meaning set forth in Section
          9.10.2(c) hereof.

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     1.35. "EXECUTIVE OFFICERS" shall mean the President of Wyeth
          Pharmaceuticals (or an executive officer of Wyeth designated by such
          President of Wyeth Pharmaceuticals) and the Chief Executive Officer of
          Trubion (or an executive officer of Trubion designated by such Chief
          Executive Officer).

     1.36. "EXERCISE NOTICE" shall have the meaning set forth in Section
          9.10.2(c) hereof.

     1.37. "EXISTING ACTIVITIES" shall have the meaning set forth in Section
          9.10.2(c) hereof.

     1.38. "EXISTING TRADEMARKS" shall have the meaning set forth in Section
          9.7.1(a).

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

     1.40. "FD&C ACT" shall mean the United States Federal Food, Drug, and
          Cosmetic Act (21 U.S.C. Section 301 et seq.), as amended, and the
          rules and regulations promulgated thereunder.

     1.41. "FIRST COMMERCIAL SALE" shall mean, with respect to a given Licensed
          Product and any country in the Territory, the first sale or transfer
          for value of such Licensed Product under this Agreement by Wyeth or
          its sublicensees to a Third Party in such country following receipt of
          marketing authorization from the appropriate Regulatory Authority
          permitting commercial sale of such Licensed Product in such country.

     1.42. "FOLLOW-ON CD20 PRODUCT" shall mean any product containing a
          Follow-On CD20 SMIP.

     1.43. "FOLLOW-ON CD20 SMIP" shall mean any SMIP (other than TRU-015)
          directed against the CD20 Antigen or a portion thereof.

     1.44. "FTE" shall mean a full time equivalent scientific person (M.S. or
          Ph.D. level) year, consisting of a minimum of a total of one thousand
          eight hundred eighty (1,880) hours per year of scientific work by an
          employee of Trubion on or directly related to and in support of the
          Research Program. Work on or directly related to the Research Program
          can include, but is not limited to, experimental preclinical
          laboratory and research work, recording and writing up results,
          reviewing literature and references, holding scientific discussions,
          managing and leading scientific staff and carrying out management
          duties, in each case where such activities are directly related to the
          Research Program.

     1.45. "HAS THE SAME SEQUENCE" shall mean, with respect to a specific
          protein (as described by an amino acid sequence identified by a
          GenBank accession number; a "New Protein"), that another specific
          protein (as described by an

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          amino acid sequence identified by a GenBank accession number; each, a
          "Deposited Protein") has at least *** amino acid sequence identity
          over at least *** of the length of the New Protein.

          By way of example only, if the New Protein consists of *** amino
          acids, and any contiguous sequence of *** amino acids contained in the
          Deposited Protein has at least *** sequence identity to any contiguous
          sequence of *** amino acids in the New Protein (that is, at least ***
          of the *** contiguous amino acids in such Deposited Protein sequence
          are identical to any *** of any *** contiguous amino acids in such New
          Protein), then the New Protein Has The Same Sequence as the Deposited
          Protein.

     1.46. ***

     1.47. ***

     1.48. ***

     1.49. ***

     1.50. "HSR ACT" shall mean the Hart-Scott-Rodino Antitrust Improvements Act
          of 1976, as amended, and the rules and regulations promulgated
          thereunder.

     1.51. "HSR FILING" shall mean filings by Wyeth and Trubion with the United
          States Federal Trade Commission and the Antitrust Division of the
          United States Department of Justice of a Notification and Report Form
          for Certain Mergers and Acquisitions (as that term is defined in the
          HSR Act) with respect to the matters set forth in this Agreement,
          together with all required documentary attachments thereto.

     1.52. "HSR CLEARANCE DATE" shall mean the earliest date on which the
          Parties have actual knowledge that all applicable waiting periods
          under the HSR Act with respect to the transactions contemplated
          hereunder have expired or have been terminated.

     1.53. "IND" shall mean an Investigational New Drug Application, as defined
          in the FD&C Act, that is required to be filed with the FDA before
          beginning clinical testing of a Licensed Product in human subjects, or
          an equivalent foreign filing.

     1.54. "INDEMNIFIED PARTY" shall have the meaning set forth in Section 10.3
          hereof.

     1.55. "INDEMNIFYING PARTY" shall have the meaning set forth in Section 10.3
          hereof.

     1.56. "INITIAL TERM" shall have the meaning set forth in Section 3.3.1
          hereof.

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     1.57. "JDC" shall have the meaning set forth in Section 4.7 hereof.

     1.58. "JOINT INVENTION(S)" shall have the meaning set forth in Section
          6.1.1 hereof.

     1.59. "JOINT KNOW-HOW" shall mean that Know-How related to the Licensed
          Products that is jointly owned by the Parties in accordance with
          Section 6.1.1 of this Agreement.

     1.60. "JOINT PATENT COMMITTEE" shall mean the committee described in
          Section 6.1.3 hereof.

     1.61. "JOINT PATENT RIGHT(S)" shall mean those Patent Right(s) that claim
          Joint Know-How or Joint Invention(s).

     1.62. "JOINT TECHNOLOGY" shall mean the Joint Patent Rights, the Joint
          Inventions and the Joint Know-How.

     1.63. "JPT" shall have the meaning set forth in Section 4.8 hereof.

     1.64. "JRC" shall have the meaning set forth in Section 3.4.1 hereof.

     1.65. "JRC LIAISON" shall mean a JRC member designated by a Party as its
          "JRC Liaison" in accordance with Section 3.4.3 hereof.

     1.66. "KNOW-HOW" shall mean inventions, discoveries, data, information,
          processes, methods, techniques, materials, technology, results or
          other know-how, whether or not patentable.

     1.67. "LIABILITIES" shall have the meaning set forth in Section 10.1
          hereof.

     1.68. "LICENSED PRODUCT(S)" shall mean any Product(s) or Combination
          Product(s).

     1.69. "LICENSED TARGET(S)" shall mean any Trubion Target(s) or Wyeth
          Target(s), so long as they remain the subject of the licenses granted
          to Wyeth under this Agreement.

     1.70. "MAJOR INDICATION(S)" shall mean, with respect to any CD20 Product,
          any indication with a prevalence-based patient population of at least
          two hundred thousand (200,000) patients in the United States,
          including, without limitation, non-Hodgkin's lymphoma, rheumatoid
          arthritis, systemic lupus erythematosus, Crohn's disease and multiple
          sclerosis.

     1.71. "MAJOR MARKET COUNTRY" shall mean any of the United States, the
          United Kingdom, France, Germany, Italy, Spain or Japan.

                                                                               7

<PAGE>

     1.72. "MANUFACTURING" or "MANUFACTURE" shall mean activities directed to
          producing, manufacturing, processing, filling, finishing, packaging,
          labeling, quality assurance testing and release, shipping and storage
          of a product.

     1.73. "NCBI" shall have the meaning set forth in Section 3.2.1 hereof.

     1.74. "NDA" shall have the meaning set forth in Section 1.100 hereof.

     1.75. "NET COMBINATION SALE AMOUNT" shall have the meaning set forth in
          Section 1.76 hereof.

     1.76. "NET SALES" shall mean the gross amounts charged for sales of
          Licensed Products (on which payments are due under this Agreement) by
          Wyeth or its sublicensees to Third Parties, less the sum of (a) and
          (b) where (a) is a provision, determined under Generally Accepted
          Accounting Principles in the United States and in accordance with
          Wyeth's customary and usual accrual procedures, consistently applied,
          for the accrual of (i) trade, cash, quantity and wholesaler discounts
          or rebates (other than price discounts granted at the time of sale),
          if any, allowed or paid, (ii) credits or allowances given or made for
          rejection or return of, previously sold Licensed Products or for
          retroactive price reductions (including Medicaid, managed care and
          similar types of rebates), (iii) taxes, duties or other governmental
          charges levied on or measured by the billing amount (excluding income
          and franchise taxes), as adjusted for rebates and refunds, and (iv)
          charges for packing, freight, and shipping to the extent included in
          the invoice price and (b) is a periodic adjustment (positive or
          negative, as applicable), determined under Generally Accepted
          Accounting Principles in the United States and in accordance with
          Wyeth's customary and usual adjustment procedures, consistently
          applied, of the provision determined in (a) to reflect amounts
          actually incurred for (i), (ii), (iii) and (iv) based on amounts
          actually invoiced or as separately set forth in agreements with Third
          Parties or as deducted or paid as required by applicable law or
          regulations. (The deductions described in (i), (ii), (iii) and (iv)
          are referred to herein as "Permitted Deductions.") In the case of any
          sale of Licensed Products for consideration other than cash, Net Sales
          shall be calculated on the fair market value of the consideration
          received.

          Notwithstanding the foregoing, if a Licensed Product is sold as a
          Combination Product (a "Combination Sale"), the Net Sales for such
          Combination Product shall be the portion of such Combination Sale
          allocable to the Licensed Product determined as follows:

          Except as provided below, the Net Sales amount for a Combination Sale
          shall equal the gross amount invoiced for the Combination Sale,
          reduced by the Permitted Deductions (the "Net Combination Sale
          Amount"), multiplied by the fraction A/(A+B), where:

                                                                               8

<PAGE>

               A is the invoice price, in the country where such Combination
               Sale occurs, of the Licensed Product contained in the Combination
               Product, if sold as a separate product in such country by Wyeth
               or its sublicensees, as the case may be, and B is the aggregate
               of the invoice price or prices, in such country, of products
               which collectively contain as their respective sole active
               ingredient such other pharmaceutically active compounds or
               substances, as the case may be, included in the Combination
               Product, if sold separately in such country by Wyeth or its
               sublicensees, as applicable.

          In the event that Wyeth or its sublicensees sell the Licensed Product
          included in a Combination Product as a separate product in a country,
          but do not separately sell all of the other pharmaceutically active
          compounds or substances, as the case may be, included in such
          Combination Product in such country, the calculation of the Net Sales
          amount for such Combination Sale shall be determined by multiplying
          the Net Combination Sale Amount by the fraction A/C where:

               A is the average wholesale price, in such country, charged by
               Wyeth or its sublicensees, as the case may be, for the Licensed
               Product contained in such Combination Product, when sold as a
               separate product by Wyeth or its sublicensees, as applicable, and
               C is the average wholesale price, in such country, charged by
               Wyeth or its sublicensees, as applicable, for the entire
               Combination Product.

          In the event that Wyeth or its sublicensees do not sell the Licensed
          Product included in a Combination Product as a separate product in a
          country where such Combination Sale occurs, but do separately sell
          products which collectively contain as their respective sole active
          ingredient all of the other pharmaceutically active compounds or
          substances, as the case may be, included in the Combination Product in
          such country, the calculation of Net Sales resulting from such
          Combination Sale shall be determined by multiplying the Net
          Combination Sale Amount by the fraction (C-D)/C, where:

               C is the average wholesale price, in such country, charged by
               Wyeth or its sublicensees, as the case may be, for the entire
               Combination Product, and D is the average wholesale price charged
               by Wyeth or its sublicensees, as the case may be, for the
               products which collectively contain as their sole active
               ingredient such other pharmaceutically active compounds or
               substances, as the case may be, included in the Combination
               Product.

          Where active ingredient portions of a Combination Product are sold
          separately as other products but in different dosage strengths than
          are in the

                                                                               9

<PAGE>

          Combination Product, the calculation of the Net Sales amount for such
          Combination Product shall be based on appropriate proration of the
          amounts of each active ingredient component included therein when
          applying the formulas set forth above.

          Where the calculation of Net Sales resulting from a Combination Sale
          in a country cannot be determined by any of the foregoing methods, the
          calculation of Net Sales for such Combination Sale shall be that
          portion of the Net Combination Sale Amount reasonably determined in
          good faith by the Parties as properly reflecting the value of the
          Licensed Product included in the Combination Product.

          Notwithstanding the foregoing, Net Sales shall not include any
          reimbursement received by Wyeth or its sublicensees in respect of the
          use of a Licensed Product in a country solely as part of a clinical
          trial prior to the receipt of marketing authorization required to
          commence commercial sales of such Licensed Product in such country.

     1.77. "NEW PROTEIN" shall have the meaning set forth in Section 1.45
          hereof.

     1.78. "NICHE INDICATION(S)" shall mean, with respect to any CD20 Product,
          any indication, including, but not limited to, ***, for such CD20
          Product other than a Major Indication.

     1.79. "NOTICE OF BREACH" shall have the meaning set forth in Section 9.5
          hereof.

     1.80. "NOTICE OF MODIFICATION" shall have the meaning set forth in Section
          9.5 hereof.

     1.81. "NOTICE OF TERMINATION" shall have the meaning set forth in Section
          9.5 hereof.

     1.82. "OTHER PRODUCT" shall mean any product containing a SMIP directed
          against a Wyeth Target or a portion thereof.

     1.83. "PART(Y/IES)" shall have the meaning set forth in the preamble
          hereof.

     1.84. "PATENT RIGHTS" shall mean any and all (a) patents, (b) pending
          patent applications, including, without limitation, all provisional
          applications, substitutions, continuations, continuations-in-part,
          divisions, renewals, and all patents granted thereon, (c) all
          patents-of-addition, reissues, reexaminations and extensions or
          restorations by existing or future extension or restoration
          mechanisms, including, without limitation, supplementary protection
          certificates or the equivalent thereof, (d) inventor's certificates,
          and (e) all United States and foreign counterparts of any of the
          foregoing.

                                                                              10

<PAGE>

     1.85. "PERSON" shall mean an individual, sole proprietorship, partnership,
          limited partnership, limited liability partnership, corporation,
          limited liability company, business trust, joint stock company, trust,
          incorporated association, joint venture or similar entity or
          organization, including a government or political subdivision,
          department or agency of a government.

     1.86. "PERMITTED DEDUCTION" shall have the meaning set forth in Section
          1.76 hereof.

     1.87. "PHASE I CLINICAL STUDY" shall mean a study of a Licensed Product in
          human subjects with the endpoint of determining initial tolerance,
          safety or pharmacokinetic information in single dose, single ascending
          dose, multiple dose and/or multiple ascending dose regimens.

     1.88. "PHASE II CLINICAL STUDY" shall mean a study of a Licensed Product in
          human patients to determine initial efficacy and dose range finding
          before embarking on Phase III Clinical Studies.

     1.89. "PHASE IIA CLINICAL STUDY" shall mean Trubion's TRU-015 Protocol
          15001.

     1.90. "PHASE IIB CLINICAL STUDY" shall mean Trubion's TRU-015 Protocol
          15002.

     1.91. "PHASE III CLINICAL STUDY" shall mean a pivotal study (whether or not
          denominated a "Phase III" clinical study under applicable regulations)
          in human patients with a defined dose or a set of defined doses of a
          Licensed Product designed to ascertain efficacy and safety of such
          Licensed Product for the purpose of enabling the preparation and
          submission of Regulatory Approval Applications to the competent
          Regulatory Authorities in a country of the Territory.

     1.92. "PREVIOUSLY DEPOSITED PROTEIN" shall have the meaning set forth in
          Section 3.2.4(b) hereof.

     1.93. "PRODUCT" shall mean any CD20 Product, ***, or Other Product, or any
          Conjugate of any CD20 Product, ***, or Other Product.

     1.94. "PRODUCT DATA AND FILINGS" shall mean (a) all clinical protocols,
          studies, clinical data and results used in or resulting from any
          clinical trial of any Licensed Product and (b) all INDs, Regulatory
          Approval Applications and Regulatory Approvals regarding any Licensed
          Product.

     1.95. "PRODUCT LICENSE" shall have the meaning set forth in Section 2.1.1
          hereof.

     1.96. "PRODUCT-RELATED PATENT RIGHTS" shall have the meaning set forth in
          Section 6.2.1(a) hereof.

                                                                              11

<PAGE>

     1.97. "PROVISIONAL EXCLUDED TARGET" shall mean a Target described in
          Section 3.2.4 hereof as a Provisional Excluded Target.

     1.98. "RECEIVING PARTY" shall have the meaning set forth in Section 7.1
          hereof.

     1.99. "RECOMBINANT DNA" shall mean the DNA sequences encoding any SMIP
          including, without limitation, any DNA plasmid expression construct
          encoding any such SMIP.

     1.100. "REGULATORY APPROVAL" shall mean the technical, medical and
          scientific licenses, registrations, authorizations and approvals
          (including, without limitation, approvals of New Drug Applications
          ("NDAs") or Biologic License Applications ("BLAs"), supplements and
          amendments, pre- and post- approvals, pricing approvals, and labeling
          approvals) of any national, supra-national, regional, state or local
          regulatory agency, department, bureau, commission, council or other
          governmental entity, necessary for the commercial Manufacture,
          distribution, marketing, promotion, offer for sale, use, import,
          export and sale of Licensed Product(s) in a regulatory jurisdiction in
          the Territory. For the sake of clarity, Regulatory Approval shall not
          be deemed to have been obtained in a country other than the United
          States until any applicable governmental pricing approvals have also
          been obtained in such country. Regulatory Approval of a Licensed
          Product shall be deemed to have been obtained in the United States
          immediately upon BLA approval for such Licensed Product in the United
          States.

     1.101. "REGULATORY APPROVAL APPLICATION" shall mean an application
          submitted to the appropriate Regulatory Authority seeking Regulatory
          Approval of a Licensed Product for use in one or more therapeutic
          indications in a regulatory jurisdiction within the Territory.

     1.102. "REGULATORY AUTHORIT(Y/IES)" shall mean any national (e.g., the
          FDA), supra-national (e.g., the European Commission, the Council of
          the European Union, or the European Agency for the Evaluation of
          Medicinal Products), regional, state or local regulatory agency,
          department, bureau, commission, council or other governmental entity
          in each country of the Territory involved in the granting of
          Regulatory Approval for a Licensed Product.

     1.103. "RELEASED TARGET" shall have the meaning set forth in Section 3.2.2
          hereof.

     1.104. "REPLACEMENT TARGET" shall have the meaning set forth in Section
          3.2.3 hereof.

     1.105. "RESEARCH BUDGET" shall have the meaning set forth in Section 3.5
          hereof.

     1.106. "RESEARCH PLAN" shall mean the written plan for the conduct of the
          Research Program described in Section 3.5 hereof as approved and
          amended by the Parties in accordance with Section 3.5 hereof.

                                                                              12

<PAGE>

     1.107. "RESEARCH PROGRAM" shall have the meaning set forth in Section 3.1
          hereof.

     1.108. "RESEARCH PROGRAM DATA" shall have the meaning set forth in Section
          3.7 hereof.

     1.109. "RESEARCH TERM" shall have the meaning set forth in Section 3.3.1
          hereof.

     1.110. "ROYALTY PERIOD" shall mean the period of time beginning on the date
          of the First Commercial Sale of a Licensed Product in any country and,
          on a Licensed Product-by-Licensed Product and country-by-country
          basis, extending until the earlier of (a) the termination of this
          Agreement pursuant to Article 9 hereof with respect to such Licensed
          Product in such country or (b) the later of (i) the date on which the
          last Valid Claim included within the Trubion Technology ceases to be a
          Valid Claim, which Valid Claim would be infringed by the composition,
          Manufacture, use, sale, offer for sale or importing of such Licensed
          Product in such country, or (ii)(A) with respect to CD20 Products, the
          *** anniversary of the First Commercial Sale for the first Major
          Indication of such CD20 Product in such country (provided, however,
          that if such CD20 Product has received Regulatory Approval for a Niche
          Indication in such country but has not received Regulatory Approval
          for a Major Indication in such country, the Royalty Period as defined
          under and for purposes of this clause (ii)(A) for such CD20 Product in
          such country shall be suspended beginning on the *** anniversary of
          the First Commercial Sale of such CD20 Product in such country until
          such time, if at all, as Regulatory Approval has been obtained
          permitting the marketing of such CD20 Product for a Major Indication
          in such country, at which point such Royalty Period shall commence
          with respect to such CD20 Product for a Major Indication) and (B) with
          respect to each other Licensed Product, the *** anniversary of the
          First Commercial Sale of such Licensed Product in such country.

     1.111. "SIGNING DATE" shall have the meaning set forth in the preamble
          hereof.

     1.112. "SMIP(S)" or small modular immuno-pharmaceutical(s) shall mean a
          single chain polypeptide that (i) *** (ii) binds with specificity to a
          target antigen, (iii) has a binding domain, and (iv) may have an
          effector domain which may or may not have effector function, ***.

     1.113. "SMIP IMPROVEMENT" shall mean an invention consisting of any
          modification to the polynucleotide sequence encoding or the amino acid
          sequence of a SMIP, if the practice of such invention would infringe
          Patent Rights Controlled by Trubion at the time such invention is
          made.

     1.114. "SPECIFICALLY BINDS" shall mean, in the case of a SMIP or other
          protein, the binding of such SMIP or other protein to a Target (or a
          portion thereof) above the level of background binding and wherein
          such SMIP or other

                                                                              13

<PAGE>

          protein is designed or being developed to exert its biological effect
          through binding to such Target (or such portion thereof).

     1.115. "SUCCESSOR PARTY" shall have the meaning set forth in Section
          9.10.2(a) hereof.

     1.116. "SUED PARTY" shall have the meaning set forth in Section 6.2.3(b)
          hereof.

     1.117. "TARGET" shall mean a specific named human protein that is
          identified as a full length protein of that name and further
          identified by up to *** GenBank accession numbers for its amino acid
          sequence, as well as any additional protein(s) that Has The Same
          Sequence as such specific named human protein.

     1.118. "TARGET CANDIDATE" shall have the meaning set forth in Section 3.2.1
          hereof.

     1.119. "TERRITORY" shall mean the entire world.

     1.120. "THIRD PART(Y/IES)" shall mean any Person(s) other than Wyeth or
          Trubion.

     1.121. "TRADEMARK" shall mean those trademarks used in connection with the
          Commercialization of any Licensed Product by Wyeth or its sublicensees
          hereunder.

     1.122. "TRU-015" shall mean the chimeric SMIP directed against the CD20
          Antigen that is currently designated by Trubion as "TRU-015," as
          further described on Exhibit 1.122 attached hereto.

     1.123. "TRU-015 PRODUCT" shall mean any product containing TRU-015.

     1.124. "TRUBION" shall have the meaning set forth in the preamble hereof.

     1.125. "TRUBION ADDITIONAL THIRD PARTY LICENSE" shall have the meaning set
          forth in Section 6.2.3(a) hereof.

     1.126. "TRUBION INDEMNIFIED PARTY" shall have the meaning set forth in
          Section 10.1 hereof.

     1.127. "TRUBION KNOW-HOW" shall mean any Know-How, other than the Joint
          Know-How, that (a) Trubion Controls as of the Effective Date or that
          comes into the Control of Trubion during the term of this Agreement
          (other than through the grant of a license by Wyeth) and (b) relates
          to any Cell Lines, Conjugates, Licensed Products, Recombinant DNA,
          SMIPs, Licensed Targets, Target Candidates or the Development,
          Manufacture or use of any of the foregoing.

                                                                              14

<PAGE>

     1.128. "TRUBION LAWYERS" shall have the meaning set forth in Section 3.2.1
          hereof.

     1.129. "TRUBION PATENT RIGHTS" shall mean Patent Rights, other than Joint
          Patent Rights, that (a) Trubion Controls as of the Effective Date or
          that come into the Control of Trubion during the term of this
          Agreement and (b) claim any Trubion Know-How. Those Trubion Patent
          Rights known to be existing as of the Signing Date are listed on
          Exhibit 1.129 attached hereto.

     1.130. "TRUBION TARGET" shall mean each of the human CD20 Antigen and/or
          ***, as the context may require.

     1.131. "TRUBION TECHNOLOGY" shall mean Trubion's interest in the Trubion
          Patent Rights, the Trubion Know-How, the Joint Technology and the
          Research Program Data.

     1.132. "TRUBION THIRD PARTY AGREEMENT(S)" shall mean the agreements
          specified on Exhibit 1.132 between Trubion and the indicated Third
          Parties that relate to the research, Development, Manufacture and/or
          Commercialization of Licensed Products under this Agreement.

     1.133. "U.S. WYETH PHARMACEUTICALS" shall have the meaning set forth in
          Section 12.5 hereof.

     1.134. "VALID CLAIM" shall mean a claim that (a) in the case of any
          unexpired United States or foreign patent, shall not have been
          dedicated to the public, disclaimed, nor held invalid or unenforceable
          by a court or government agency of competent jurisdiction in an
          unappealed or unappealable decision, or (b) in the case of any United
          States or foreign patent application, (i) shall not have been
          cancelled, withdrawn or abandoned, without being refiled in another
          application in the applicable jurisdiction, (ii) shall not have been
          finally rejected by an administrative agency or other governmental
          action from which no appeal can be taken and (iii) shall not have been
          pending for more than ***, in either case which claim (if issued)
          would cover the Manufacture, use or sale of any Licensed Product. For
          purposes of this definition, the time period for which a claim is
          pending shall begin on the priority date for such claim, and shall
          continue until such claim is either issued or is no longer deemed to
          be a Valid Claim in accordance with the preceding sentence regardless
          of whether such claim is amended or refiled in another application in
          the applicable jurisdiction. If a claim of a patent application which
          ceased to be a Valid Claim under (b) due to the passage of time later
          issues as part of a patent described within (a) then it shall again be
          considered to be a Valid Claim effective as of the issuance of such
          patent.

     1.135. "WYETH" shall have the meaning set forth in the preamble hereof.

                                                                              15

<PAGE>

     1.136. "WYETH APPLIED TECHNOLOGY" shall mean, with respect to any Licensed
          Product, that Wyeth Technology which (a) Wyeth had applied to such
          Licensed Product prior to any termination of any rights under this
          Agreement with respect to such Licensed Product, provided that such
          Wyeth Technology is necessary or useful for the continued research,
          Development, Manufacture or Commercialization of such Licensed Product
          as it exists at the time of such termination, or (b) Wyeth had
          incorporated into such Licensed Product prior to any termination of
          rights under this Agreement with respect to such Licensed Product;
          provided that Wyeth shall use its Commercially Reasonable Efforts to
          sublicense or otherwise transfer rights under any Third-Party license
          to which the use or exploitation of such Wyeth Applied Technology is
          subject; and further provided, however, that with respect to each of
          clauses (a) and (b) of this Section 1.136, such Wyeth Technology shall
          not include any of Wyeth's conjugation technology.

     1.137. "WYETH INDEMNIFIED PARTY" shall have the meaning set forth in
          Section 10.2 hereof.

     1.138. "WYETH KNOW-HOW" shall mean any Know-How, other than the Joint
          Know-How, that (a) Wyeth Controls as of the Effective Date or that
          comes into the Control of Wyeth (other than as a result of the
          licenses granted by Trubion to Wyeth under Section 2.1 hereof) during
          the term of this Agreement and (b) relates to the Cell Lines,
          Conjugates, Recombinant DNA, Licensed Products, SMIPs, Target
          Candidates or Licensed Targets or the Development, Manufacture, use or
          Commercialization of any of the foregoing.

     1.139. "WYETH PATENT RIGHTS" shall mean Patent Rights, other than the Joint
          Patent Rights, that (a) Wyeth Controls as of the Effective Date or
          that come into the Control of Wyeth (other than as a result of the
          licenses granted by Trubion to Wyeth under Section 2.1 hereof) during
          the term of this Agreement and (b) claim any Wyeth Know-How.

     1.140. "WYETH TARGETS" shall mean the Targets designated by Wyeth under the
          Research Program, as described in Section 3.2 hereof.

     1.141. "WYETH TECHNOLOGY" shall mean Wyeth's interest in the Wyeth Patent
          Rights, the Wyeth Know-How, the Joint Technology and the Research
          Program Data.

2.   LICENSES.

     2.1. LICENSES TO WYETH.

          2.1.1. EXCLUSIVE LICENSES. Subject to the terms and conditions of this
               Agreement, Trubion, effective as of the Effective Date, hereby
               grants to Wyeth an exclusive license (exclusive even as to
               Trubion,

                                                                              16

<PAGE>

               except to the extent necessary for Trubion to perform its
               obligations under this Agreement), with the right to grant
               sublicenses in accordance with the provisions of Section 2.4
               hereof, under the Trubion Technology, to research, Develop, have
               Developed, make, have made, Manufacture, use, have used, import,
               have imported, export, have exported, distribute, have
               distributed, market, have marketed, offer and have offered for
               sale, sell, have sold and Commercialize (subject to Section 4.11)
               Licensed Products in the Territory (the license granted under
               this Section 2.1.1 is sometimes referred to herein as the
               "Product License").

          2.1.2. RETAINED RIGHTS OF TRUBION. For the avoidance of doubt, but
               subject to Sections 2.3 and 3.2 hereof, Trubion shall retain: (a)
               all rights under the Trubion Technology with respect to the
               research, Development, Manufacture, use and Commercialization of
               SMIPs that (i) *** to Targets that are not Licensed Targets and
               (ii) do not *** to any Licensed Targets; and (b) the right to use
               SMIPs which *** to one or more Licensed Targets in in vitro
               studies conducted solely as part of Trubion's internal research
               efforts, provided, however, that Trubion shall not provide any
               such SMIP (that *** to a Licensed Target) to any Third Party or
               utilize any such SMIP (that *** to a Licensed Target) in a
               collaboration with any Third Party, except with Wyeth's prior
               written consent.

     2.2. LICENSE TO TRUBION. Wyeth hereby grants to Trubion a royalty-free
          non-exclusive license, with no right to grant sublicenses, under the
          Wyeth Technology, solely for the purpose of, and limited to, Trubion's
          use of the Wyeth Technology in connection with the Trubion Technology
          to research, Develop, have Developed, make, have made, use and have
          used Licensed Products to fulfill its obligations under this
          Agreement. In addition, Wyeth hereby grants to Trubion the
          non-exclusive license under Wyeth's rights to Covered SMIP
          Improvements as set forth in greater detail in Section 6.1.2.

     2.3. EXCLUSIVITY.

          2.3.1. CD20 PRODUCT EXCLUSIVITY. Subject to Section 2.3.3, and except
               for Development of the CD20 Products pursuant to the terms of
               this Agreement, neither Party shall Develop any human therapeutic
               product that contains a protein that *** to the CD20 Antigen
               during the time period beginning on the Effective Date and ending
               on the earlier of: (a) the First Commercial Sale of any CD20
               Product for a Major Indication in a Major Market Country or (b)
               the termination of the licenses granted by Trubion to Wyeth under
               this Agreement with respect to all CD20 Products.

                                                                              17

<PAGE>

               Subject to Section 2.3.3, and except for Commercialization of the
               CD20 Products pursuant to the terms of this Agreement, neither
               Party shall Commercialize any human therapeutic product that
               contains a protein that *** to the CD20 Antigen during the time
               period beginning on the Effective Date and ending on the earlier
               of: (a) five (5) years after the First Commercial Sale of any
               CD20 Product for a Major Indication in a Major Market Country or
               (b) the termination of the licenses granted by Trubion to Wyeth
               under this Agreement with respect to all CD20 Products.

          2.3.2. *** EXCLUSIVITY. Subject to Section 2.3.3, and except for
               Development of the *** pursuant to the terms of this Agreement,
               neither Party shall Develop any human therapeutic product that
               contains a protein that *** to the *** during the time period
               beginning on the Effective Date and ending on the earlier of: (a)
               the First Commercial Sale of any *** in any Major Market Country
               or (b) the termination of the licenses granted by Trubion to
               Wyeth under this Agreement with respect to all ***.

               Subject to Section 2.3.3, and except for Commercialization of the
               *** pursuant to the terms of this Agreement, neither Party shall
               Commercialize any human therapeutic product that contains a
               protein that *** to the *** during the time period beginning on
               the Effective Date and ending on the earlier of: (a) five (5)
               years after the First Commercial Sale of any *** in any Major
               Market Country or (b) the termination of the licenses granted by
               Trubion to Wyeth under this Agreement with respect to all ***.

          2.3.3. LIMITATIONS. The exclusivity provisions of Sections 2.3.1 and
               2.3.2 above (a) shall not apply to Wyeth's Manufacture of any
               product for a Third Party pursuant only to a contract
               manufacturing or supply agreement between Wyeth and such Third
               Party where Wyeth is acting only as a contract manufacturer or
               supplier for such Third Party, (b) shall in no way limit any of
               the licenses granted by Trubion to Wyeth under Section 2.1
               hereof, and (c) shall in no way limit any of the retained rights
               of Trubion set forth in Section 2.1.2 hereof.

     2.4. SUBLICENSING. Wyeth may grant to one or more Third Parties sublicenses
          of the rights granted to it under Section 2.1 hereof at any time;
          provided that Wyeth shall execute a written agreement with each such
          sublicensee and shall comply with the following: Each such sublicense
          (a) shall be subject and subordinate to, and consistent with, the
          terms and conditions of this Agreement, (b) shall not in any way
          diminish, reduce or eliminate any of Wyeth's obligations under this
          Agreement, (c) shall require each such

                                                                              18

<PAGE>

          sublicensee to comply with all applicable terms of this Agreement,
          including to keep books and records, and permit Wyeth to audit (either
          directly or through an independent auditor) such books and records,
          and (d) shall provide that any such sublicensee shall not further
          sublicense except on terms consistent with this Section 2.4. Wyeth
          shall provide Trubion with a copy of each such sublicense agreement
          within thirty (30) days after the execution thereof. Such copy may be
          redacted to exclude confidential, non-Licensed Product-related
          information and financial information (other than such financial
          information that is necessary for assessing the obligations to Trubion
          under this Agreement). Upon Trubion's request and at Trubion's
          expense, Wyeth shall exercise its right to conduct an audit of a
          sublicensee's books and records pertaining to the sale of a Licensed
          Product under any such sublicense agreement at the next time that
          conducting such an audit is permissible under such sublicense
          agreement. Wyeth shall provide Trubion with a copy of the report of
          the findings made in any such audit. If such audit reveals that such
          sublicensee has understated its Net Sales by *** or more, Wyeth shall
          be responsible for the costs of the audit. Wyeth shall remain
          responsible for its obligations hereunder and for the performance of
          its sublicensees (including, without limitation, making all payments
          due Trubion by reason of any Net Sales of Licensed Products), and
          shall ensure that any such sublicensees comply with all relevant
          provisions of this Agreement. In the event of any uncured material
          breach by any sublicensee under a sublicense agreement that would
          constitute a breach of Wyeth's obligations under this Agreement, Wyeth
          will promptly inform Trubion in writing and shall take such action
          which in Wyeth's reasonable business judgment will address such
          default; provided, however, any such uncured material breach by such
          sublicensee of an obligation that would constitute a breach of Wyeth's
          obligations under this Agreement shall be deemed an uncured material
          breach of Wyeth hereunder unless Wyeth cures such material breach
          within the time provided under Section 9.5 hereof.

     2.5. DIRECT LICENSES TO AFFILIATES. Wyeth may at any time request and
          authorize Trubion to grant licenses within the scope of Section 2.1
          directly to Affiliates of Wyeth by giving written notice designating
          to which Affiliate a direct license is to be granted. Upon receipt of
          any such notice, Trubion shall enter into and sign a separate direct
          license agreement with such designated Affiliate of Wyeth. All such
          direct license agreements shall be consistent with the terms and
          conditions of this Agreement, except for such modifications as may be
          required by the laws and regulations in the country in which the
          direct license will be exercised; provided, however, that Trubion
          shall have no obligation to enter into any such direct license
          agreement if the effect of entering into such agreement (and
          continuing as a Party to this Agreement) would be to increase the
          level of obligations owed by Trubion, decrease the obligations owed to
          Trubion or the enforceability thereof, or decrease the consideration
          owed to Trubion relative to the obligations owed by or to, or the
          consideration owed to,

                                                                              19

<PAGE>

          Trubion under this Agreement, had such direct license(s) not been
          granted. In countries where the validity of such direct license
          agreement requires prior government approval or registration, such
          direct license agreement shall not become binding between the parties
          thereto until such approval or registration is granted, which approval
          or registration shall be obtained by Wyeth. All costs of making such
          direct license agreement(s), including Trubion's reasonable attorneys'
          fees, under this Section 2.5 shall be borne solely by Wyeth.

     2.6. RIGHT OF REFERENCE. Trubion hereby grants to Wyeth a "Right of
          Reference," as that term is defined in 21 C.F.R. Section 314.3(b), to
          any data Controlled by Trubion that relates to any CD20 Product (and
          any other Licensed Product, to the extent applicable), and Trubion
          shall provide a signed statement to this effect, if requested by
          Wyeth, in accordance with 21 C.F.R. Section 314.50(g)(3).

     2.7. SECTION 365(N) OF BANKRUPTCY CODE. All rights and licenses now or
          hereafter granted under or pursuant to any Section of this Agreement,
          including Sections 2.1 and 2.5 hereof, are rights to "intellectual
          property" (as defined in Section 101(35A) of Title 11 of the United
          States Code, as amended (such Title 11, the "Bankruptcy Code")). In
          the event this Agreement is rejected under Section 365 of the
          Bankruptcy Code, Trubion hereby grants to Wyeth, subject to Wyeth's
          obligations under Sections 365(n)(2)(A) and (B), a right of access and
          to obtain possession of and to benefit from each of the following
          embodiments to the extent related to Wyeth's exercise of its license
          rights to any Licensed Products or otherwise related to any rights or
          licenses granted under or pursuant to any Section of this Agreement:
          (i) copies of pre-clinical and clinical research data and results,
          (ii) aliquots of laboratory samples, (iii) Licensed Product samples
          and inventory, (iv) Cell Lines expressing Licensed Products, libraries
          encoding Licensed Products or components thereof and sequences
          thereof, (v) copies of laboratory notes and notebooks pertaining to
          Licensed Products, (vi) copies of data and results related to clinical
          trials of Licensed Products, (vii) regulatory filings and approvals of
          Licensed Products, (viii) rights of reference in respect of regulatory
          filings and approvals of Licensed Products, and (ix) plasmid and
          vectors encoding Licensed Product SMIPs, all of which constitute
          "embodiments" of intellectual property pursuant to Section 365(n) of
          the Bankruptcy Code, and (xi) all other embodiments of such
          intellectual property in Trubion's possession or control. Recognizing
          that the embodiments described above may be useful or necessary to
          Trubion in connection with its continued operation of its business,
          and that a Third Party may also have a right of access to such
          embodiment under Section 365(n) of the Bankruptcy Code or applicable
          non-bankruptcy law, where there is a fixed or limited quantity of any
          biological material or other tangible item of such embodiment
          described above, Wyeth shall be entitled to a pro rata portion
          thereof. Trubion agrees not to interfere with Wyeth's exercise under
          the Bankruptcy Code of rights and licenses to intellectual

                                                                              20

<PAGE>

          property licensed hereunder and embodiments thereof in accordance with
          this Agreement and agrees to use Commercially Reasonable Efforts
          (short of any obligation of Trubion to incur expenses in connection
          therewith) to assist Wyeth to obtain such intellectual property and
          embodiments thereof in the possession or control of Third Parties as
          reasonably necessary or useful for Wyeth to exercise such rights and
          licenses in accordance with this Agreement; provided, however, that
          Trubion's Commercially Reasonable Efforts for purposes of this Section
          2.7 shall not be deemed to include an obligation to make payments to
          Third Parties to obtain such intellectual property rights and
          embodiments thereof. The Parties hereto acknowledge and agree that
          reimbursement payments pursuant to Sections 3.6 and 4.6 and all other
          payments by Wyeth to Trubion hereunder other than royalty payments
          pursuant to Section 5.4 and Additional Research and Development
          Expense Payments under Section 5.3 do not constitute royalties within
          the meaning of Bankruptcy Code Section 365(n) or relate to licenses of
          intellectual property hereunder.

     2.8. NO IMPLIED RIGHTS. Except as expressly provided in this Agreement,
          neither Party shall be deemed by estoppel or implication to have
          granted the other Party any license or other right with respect to any
          intellectual property of such Party.

3.   RESEARCH PROGRAM.

     3.1. SCOPE AND CONDUCT OF THE RESEARCH PROGRAM. Under the terms and
          conditions set forth herein, Trubion and Wyeth shall collaborate
          through one or more joint project teams in the conduct of a
          pre-clinical research program to identify and evaluate (a) SMIPs
          directed against Licensed Targets and (b) Licensed Products, including
          CD20 Products, *** and Other Products (collectively, the "Research
          Program"). Such activities shall include, but not be limited to, the
          following:

               ***

          Subject to and in accordance with the Research Plan and the
          Development Plan (to the extent applicable), the JRC shall determine
          the appropriate activities to be undertaken by Trubion and Wyeth;
          provided, however, that, as of the Signing Date, the Parties
          anticipate that Trubion shall conduct activity (i) above (with input
          from Wyeth), Wyeth shall conduct activities (v), (vi) and (vii) above,
          and Trubion and Wyeth shall jointly conduct activities (ii), (iii) and
          (iv) above. The Research Program shall be conducted in accordance with
          the Research Plan, and each Party shall use its Commercially
          Reasonable Efforts to perform all of its obligations under the
          Research Program in accordance with the Research Plan and current good
          laboratory practices.

     3.2. DESIGNATION OF TARGETS.

                                                                              21

<PAGE>

          3.2.1. TARGET CANDIDATES. Within thirty (30) days after the Effective
               Date, Wyeth shall provide Trubion's Vice President, Legal Affairs
               & Chief Patent Counsel with a list of up to *** Targets (each a
               "Target Candidate") from which Wyeth shall have the exclusive
               right, until ***, to designate up to *** Wyeth Targets, in
               accordance with the following provisions (subject to Wyeth's
               right under Section 3.2.3 to designate as Wyeth Targets up to ***
               Targets (of the *** Targets that Wyeth may designate as Wyeth
               Targets) that are not Target Candidates at the time of
               selection). In the case of protein Targets that are Target
               Candidates, Wyeth shall designate each such Target Candidate on
               the list by its GenBank accession number provided by the National
               Center for Biotechnology Information ("NCBI") (including any
               nomenclature describing such Target Candidate that is provided
               therewith) or, if an NCBI GenBank accession number is not
               available for such Target Candidate, by its nucleotide and amino
               acid sequences. For the avoidance of doubt, Wyeth may not
               designate as Target Candidates any Targets that are Excluded
               Targets. Subject to the following procedures, Trubion shall not
               undertake any research or Development activities beyond Milestone
               One (as defined on Exhibit 3.2.1 attached hereto) of Trubion's
               internal product development process, or propose to enter into or
               enter into any agreement with any Third Party with respect to any
               SMIP directed against any Target Candidate or with respect to any
               Licensed Product containing such a SMIP, unless and until such
               Target Candidate becomes a Released Target, Excluded Target or
               Provisional Excluded Target. Trubion, through its Legal
               Department, shall maintain a copy of the list of Target
               Candidates in a secure location. Trubion shall take reasonable
               measures and implement reasonable procedures to ensure that only
               its inside attorneys who are employees of its Legal Department
               and its outside patent counsel (collectively, "Trubion Lawyers")
               have knowledge of and access to Wyeth's Target Candidate list.
               The Target Candidate list shall be considered Confidential
               Information of Wyeth, and except as expressly permitted under
               this Section 3.2 or otherwise under this Agreement, Trubion shall
               not use or disclose the Target Candidate list or the information
               set forth therein to any of its Affiliates, to any Third Party,
               or to any employees, officers or agents of Trubion other than
               Trubion Lawyers. For so long as a Target remains a Target
               Candidate, Trubion, through its Legal Department, shall implement
               reasonable procedures to maintain records of all Third Party
               inquiries to Trubion and Trubion's responses to same, relating to
               the Target Candidate list made pursuant to this Section 3.2. The
               Trubion Legal Department

                                                                              22

<PAGE>

               shall also maintain the list of Released Targets, Excluded
               Targets and Provisional Excluded Targets in accordance with the
               provisions of Sections 3.2.2 and 3.2.4. In the event of a bona
               fide dispute arising under this Agreement relating to the Target
               selection process described in this Section 3.2, Trubion shall
               provide to an independent Third Party selected by Wyeth and
               reasonably acceptable to Trubion access to the lists of Target
               Candidates, Released Targets, Excluded Targets and Provisional
               Excluded Targets and records and processes related thereto (to
               the extent relevant to the bona fide dispute) maintained by
               Trubion in accordance with this Section 3.2. Such independent
               Third Party may only communicate to Wyeth whether or not the
               Target selection process was properly performed by Trubion's
               Lawyers.

          3.2.2. RELEASED TARGETS. On or before the ***, Wyeth, by written
               notice to Trubion's Vice President, Legal Affairs & Chief Patent
               Counsel, shall identify *** Target Candidates from the list
               delivered pursuant to Section 3.2.1 (inclusive of any Target
               Candidates that have become Released Targets during such period
               pursuant to Section 3.2.4 hereof), which from the date of such
               identification shall cease to be Target Candidates (each, a
               "Released Target"). At the time that a Target Candidate becomes a
               Released Target, Trubion, subject to Section 2.8, shall be free
               to undertake research and Development activities independent of
               obligations under this Agreement, and to enter into discussions
               or an agreement with a Third Party, with respect to SMIPs
               directed against any such Released Target or any other activities
               in connection with such Released Target. On or before the ***,
               Wyeth, by written notice to Trubion, shall identify such
               additional Target Candidates from the list delivered pursuant to
               Section 3.2.1, if any, as additional Released Targets, such that
               there are no more than *** Target Candidates remaining on the
               list delivered pursuant to Section 3.2.1 (less the number of
               Wyeth Targets that were Target Candidates at the time of
               selection as a Wyeth Target(s) pursuant to Section 3.2.3), which
               from the date of such identification shall cease to be Target
               Candidates and, thereafter each shall also become a Released
               Target. At the end of the Research Term, all remaining Target
               Candidates, if any, shall become Released Targets.

          3.2.3. WYETH TARGETS. Wyeth Targets shall be designated only from
               either (a) Target Candidates that have not become Released
               Targets, or (b) any other Target (including a Released Target
               that is or becomes available, as described below) that is not
               then an Excluded Target or a Provisional Excluded Target;
               provided, however, that no more than *** of the Targets
               designated by

                                                                              23

<PAGE>

               Wyeth as Wyeth Targets may be Targets that are not Target
               Candidates at the time of selection. Subject to the foregoing
               sentence, Wyeth shall designate: (y) *** Target Candidates or
               other Targets as Wyeth Targets on or before ***; and (z) up to
               *** Target Candidates or other Targets (inclusive of those
               designated as Wyeth Targets during the ***) as Wyeth Targets on
               or before the second anniversary of the Effective Date; provided,
               however, if Wyeth does not designate a total of *** Wyeth Targets
               on or before such ***, then the lesser number of Wyeth Targets so
               designated shall be the total number of Wyeth Targets under this
               Agreement unless Wyeth extends the Research Program, in which
               case Wyeth may designate, before ***, one or more additional
               Wyeth Targets (up to a cumulative *** in the aggregate). For the
               avoidance of doubt and subject to the following sentence, Wyeth
               may designate only up to a *** Wyeth Targets from the Effective
               Date of this Agreement through the end of the Research Program
               (even if extended). During the term of the Research Program,
               Wyeth shall have the right to ***; provided that *** (a
               "Replacement Target") must be ***. In the event that Wyeth
               nominates as a Wyeth Target (whether as a proposed initial
               designation of a Wyeth Target or as a replacement designation as
               a Wyeth Target) a Target that is not then a Target Candidate,
               Trubion's Legal Department, within ten (10) business days after
               receiving written notice of such nomination, shall determine and
               advise Wyeth in writing whether such Target is an Excluded Target
               or a Provisional Excluded Target, as described below (and shall
               indicate whether such Target is an Excluded Target or is a
               Provisional Excluded Target). If such Target is an Excluded
               Target or a Provisional Excluded Target, it shall not be eligible
               to be considered a Wyeth Target. If a proposed Replacement Target
               is not an Excluded Target or a Provisional Excluded Target, then
               the JRC shall either approve or disapprove designation of such
               proposed Replacement Target as a Wyeth Target; provided that the
               original Wyeth Target that Wyeth proposes to replace shall be
               automatically deemed a Released Target upon the JRC's approval of
               the designation of the Replacement Target.

          3.2.4. EXCLUDED TARGETS. Excluded Targets are not eligible to be Wyeth
               Targets for so long as they remain Excluded Targets. The Targets
               deemed "Excluded Targets" as of the Effective Date are set forth
               in Exhibit 3.2.4 attached hereto. Trubion may add additional
               Targets as Excluded Targets or Provisional Excluded Targets
               (which may be selected from Released Targets and other Targets,
               but would not include any Wyeth Targets or any Target Candidate
               that has not become a Released Target) in accordance with the
               following procedures:

                                                                              24

<PAGE>

               (A)  During the period when ***, and upon the written request of
                    a potential Third Party collaborator and/or licensee of
                    Trubion pertaining to the identification, generation and/or
                    Development of SMIPs directed against a Target or Targets,
                    Trubion's Legal Department shall promptly determine whether
                    or not any of such Targets is a Wyeth Target.

               (B)  With respect to any Target newly submitted by a Party to
                    Trubion's Legal Department hereunder, Trubion's Lawyers will
                    determine whether such submitted Target *** Licensed
                    Targets, Target Candidates, Released Targets, Excluded
                    Targets and Provisional Excluded Targets available to
                    Trubion's Lawyers (each a "Previously Deposited Protein").
                    By way of example only, *** Should Wyeth designate a Target
                    that is not a protein, the Parties agree to negotiate in
                    good faith the procedure for identifying and testing whether
                    a subsequent proposed non-protein Target is the "same as"
                    such designated non-protein Target for purposes of this
                    Section 3.2.

               (C)  If Trubion's Legal Department determines, in accordance with
                    Section 3.2.4(b) above, that any such Target is a Wyeth
                    Target, Trubion shall not proceed with such potential Third
                    Party collaboration or license with respect to such Target.
                    If any of such Targets is not a Wyeth Target or a Target
                    Candidate, such Target shall automatically be deemed a
                    "Provisional Excluded Target". If such Target is a Target
                    Candidate, Trubion shall notify Wyeth in writing of
                    Trubion's request that a Target Candidate be recategorized
                    as a Released Target, in order for Trubion to be able to
                    enter substantive negotiations with such Third Party
                    regarding such Target that is a Target Candidate (i.e.,
                    Trubion shall "Put" such Target Candidate to Wyeth). Trubion
                    shall have no obligation to notify Wyeth of the identity of
                    such Third Party or the purpose of the proposed
                    collaboration or license. From the date that Trubion "Puts"
                    such Target Candidate to Wyeth, Wyeth shall have *** with
                    respect to such Puts made to Wyeth prior to ***, and shall
                    have *** with respect to such Puts made thereafter, to
                    notify Trubion in writing whether Wyeth designates such
                    Target Candidate as a Wyeth Target or recategorizes such
                    Target Candidate as a Released Target. If Wyeth fails to
                    notify Trubion within such *** period, respectively, then
                    such Target Candidate shall automatically be deemed a
                    Released Target. Any such

                                                                              25

<PAGE>

                    Released Targets shall be deemed to be Provisional Excluded
                    Targets.

               (D)  If Trubion and such potential Third Party collaborator
                    and/or licensee do not enter into a definitive agreement
                    regarding such Provisional Excluded Target within *** after
                    the date that such Target is deemed a Provisional Excluded
                    Target (such *** being subject to a *** extension by
                    Trubion, if Trubion declares, in writing, to Wyeth that at
                    least one draft definitive agreement has been exchanged
                    between Trubion and such potential Third Party collaborator
                    and/or licensee), thereafter such Provisional Excluded
                    Target would revert to being a Released Target. If Trubion
                    and such potential Third-Party collaborator and/or licensee
                    enter into a definitive agreement within the time period
                    provided above, such Provisional Excluded Target shall be
                    deemed an Excluded Target.

               (E)  During the period when ***, if Trubion itself identifies
                    internally a Target that has progressed to Milestone One (as
                    defined in Exhibit 3.2.1 attached hereto) of Trubion's
                    internal product development process, Trubion's Legal
                    Department shall promptly determine whether or not such
                    Target is a Target Candidate. If such Target is not a Target
                    Candidate, such Target shall be deemed an Excluded Target.
                    If Trubion thereafter abandons work on such Excluded Target,
                    Trubion shall notify Wyeth in writing that Trubion has
                    abandoned work on such Excluded Target and such Excluded
                    Target shall thereafter be deemed a Released Target. If such
                    Target is a Target Candidate, Trubion may Put such Target
                    Candidate to Wyeth. From the date that Trubion Puts such
                    Target Candidate to Wyeth, Wyeth shall have *** with respect
                    to such Puts made to Wyeth prior to ***, and shall have ***
                    with respect to such Puts made thereafter, to notify Trubion
                    in writing whether Wyeth designates such Target Candidate as
                    a Wyeth Target or recategorizes such Target Candidate as a
                    Released Target. If Wyeth fails to notify Trubion within
                    such ***, respectively, then such Target Candidate shall
                    automatically be deemed a Released Target. Any such Released
                    Target shall be deemed to be Excluded Target. If Trubion
                    thereafter abandons work on any such Excluded Target,
                    Trubion shall notify Wyeth in writing that Trubion has
                    abandoned work on such Excluded Target and such Excluded
                    Target shall thereafter be deemed a Released Target.

                                                                              26
<PAGE>

               (F)  With respect to the Puts described in (c) and (e) above,
                    Trubion shall not be permitted to Put more than *** Target
                    Candidates to Wyeth during the first *** of the Research
                    Program.

     3.3. TERM AND TERMINATION OF THE RESEARCH PROGRAM.

          3.3.1. RESEARCH TERM. The term of the Research Program (the "Research
               Term") shall begin on the Effective Date and shall continue until
               *** (the "Initial Term"), subject to extension as described
               below. At Wyeth's option (exercisable by providing written notice
               to Trubion no later than *** prior to the end of the Initial Term
               of the Research Program or any extension year thereof), the
               Research Term may be extended for up to *** additional ***
               periods and, thereafter, shall be renewable annually only upon
               mutual written agreement of the Parties.

          3.3.2. TERMINATION OF RESEARCH PROGRAM BY WYETH. Commencing on the
               first anniversary of the Effective Date, Wyeth shall have the
               right to terminate the Research Program, at will, at any time, in
               its entirety, upon one (1) year prior written notice to Trubion;
               provided that Trubion shall have no obligation after the
               effective termination date to complete any Research Program
               activities in connection with any Trubion Target, Wyeth Target,
               SMIP or Licensed Product. Such termination of the Research
               Program shall not constitute termination of this Agreement and
               shall not affect the Parties' rights and obligations under this
               Agreement other than those relating to the Research Program.

     3.4. JOINT RESEARCH COMMITTEE.

          3.4.1. COMPOSITION. Within thirty (30) days after the Effective Date,
               the Parties shall establish a Joint Research Committee (the
               "JRC") to oversee the Research Program. The JRC will be in effect
               only during the Research Term. The JRC shall be composed of three
               (3) representatives from each Party. Each Party may replace any
               of its representatives at any time upon written notice to the
               other Party. From time to time, the JRC may establish
               subcommittees to oversee particular projects or activities, and
               such subcommittees shall be constituted as the JRC decides.

          3.4.2. RESPONSIBILITIES. The JRC shall be responsible for
               establishing, reviewing and recommending modifications and
               updates to the Research Plan, including the Research Budget, in
               accordance with Section 3.5 hereof, monitoring and reporting to
               the Parties

                                                                              27

<PAGE>

               on activities conducted pursuant to the Research Plan, and for
               such other functions as agreed by the Parties.

          3.4.3. MEETINGS. The JRC shall meet as soon as practicable after it is
               established by the Parties and, thereafter, at such additional
               times as the Parties deem appropriate, not less frequently than
               quarterly. Each Party shall designate one of its JRC members as
               its "JRC Liaison" to co-chair meetings, prepare and circulate JRC
               meeting agendas and JRC meeting minutes. The meetings of the JRC
               shall be held in the United States, and shall alternate between
               the Parties' business locations or as otherwise decided by the
               JRC. JRC meetings may be conducted in person, by telephone or by
               videoconference. Each Party shall use reasonable efforts to cause
               its representatives to attend the meetings of the JRC. If a
               representative of a Party is unable to attend a meeting, such
               Party may designate an alternate member to attend such meeting in
               place of the absent member.

          3.4.4. VOTING. Decisions of the JRC shall be made by unanimous
               consent, with each Party having one vote. The JRC may act without
               a meeting if an action by unanimous written consent is signed by
               each Party's JRC Liaison.

          3.4.5. DISPUTE RESOLUTION. If the JRC is unable to reach agreement on
               a matter, the matter may be referred, at the request of either
               Party, for resolution through good faith discussions between
               Wyeth's Executive Vice President of Discovery Research and
               Trubion's Senior Vice President of Research and Development or
               their respective designees. Notwithstanding the foregoing, in the
               event the JRC cannot promptly resolve a disagreement or a voting
               deadlock regarding the Research Program, Wyeth's Executive Vice
               President of Discovery Research shall have the right to cast a
               tie-breaking vote to resolve any such disagreement or voting
               deadlock, such right and tie-breaking authority being subject to
               the terms and conditions of this Agreement.

          3.4.6. MINUTES. The JRC shall keep accurate and complete minutes of
               its meetings that record all proposals and recommendations made,
               and all actions and decisions taken. The JRC minutes shall not be
               effective until approved in writing by each Party's JRC Liaison.
               All records of the JRC shall be available at all times to each
               Party.

     3.5. RESEARCH PLAN. The Parties shall use their Commercially Reasonable
          Efforts to develop and approve a complete Research Plan (including a
          corresponding Research Budget) within sixty (60) days of the Effective
          Date. The Parties shall ensure that the Research Plan is consistent
          with the

                                                                              28

<PAGE>

          terms and conditions of this Agreement, and the Research Plan shall
          not impose obligations on either Party that are inconsistent with the
          terms of this Agreement. The Research Plan shall set forth generally
          (a) the activities to be undertaken by the Parties under the Research
          Program consistent with the terms of Section 3.1, (b) the utilization
          of *** Trubion FTEs in conducting such activities, (c) the anticipated
          schedule on which such activities are to be conducted, (d) the desired
          deliverables to be provided by each Party with respect to each
          Licensed Target that is the subject of the Research Program, and (e)
          the annual budget for non-ordinary expenses (as described in Section
          3.6.1 below) to be incurred by Trubion under the Research Program (the
          "Research Budget"). The JRC shall review the Research Plan, including
          the Research Budget, on at least an annual basis and submit any
          proposed modifications or updates to the Parties for review and
          approval; any such modifications or updates shall not become effective
          until approved in writing by an authorized officer of each of the
          Parties. The Parties shall review and consider any such proposed
          modifications or updates on an expeditious basis. The Parties shall
          promptly amend the Research Plan from time to time to address the
          performance of the Research Program as it relates to any Licensed
          Targets designated by Wyeth in accordance with Section 3.2 above.

     3.6. FUNDING OF THE RESEARCH PROGRAM.

          3.6.1. RESEARCH FUNDING. During each year of the Research Term (as it
               may be extended), Wyeth shall pay Trubion *** per year for
               services performed in accordance with the Research Plan. Trubion
               shall commit to the Research Program ten (10) FTEs per year to
               provide services in furtherance of the Research Program in
               accordance with the Research Plan. For the avoidance of doubt,
               Trubion may, at its sole expense and discretion, devote more than
               *** FTEs from time to time to provide services in furtherance of
               the Research Program. The *** in research funding described above
               shall be increased automatically once per calendar year by the
               percentage change in the U.S. Consumer Price Index, All Urban
               Consumers over the previous year; provided, however, that no
               increase shall be effective prior to January 1, 2007. ***.
               Trubion shall provide to Wyeth, prior to the first day of each
               Calendar Quarter, a forecast of such expenses (by major expense
               category, on an accrual basis) reimbursable under this Section
               3.6.1 which Trubion expects to incur during such Calendar Quarter
               and the subsequent three Calendar Quarters, in each case shown by
               month. Other than the foregoing amounts and except as otherwise
               expressly provided in this Agreement, each Party shall be solely
               responsible for its costs and expenses incurred in performing its
               obligations under the Research Program.

                                                                              29

<PAGE>

          3.6.2. REIMBURSEMENT PAYMENTS. Reimbursement to be made to Trubion by
               Wyeth pursuant to Section 3.6.1 will be made pursuant to invoices
               submitted by Trubion to Wyeth no more often than once with
               respect to any Calendar Quarter, within thirty (30) days of the
               end of such Calendar Quarter. Payment shall be due within
               forty-five (45) days after Wyeth receives such an invoice from
               Trubion. Each invoice must be accompanied by supporting
               documentation sufficiently demonstrating the expense so paid on a
               cash basis (such as receipts for out-of-pocket expenses and other
               written documentation reasonably acceptable to Wyeth) and by a
               certificate executed by Trubion's VP, Finance & Administration,
               of the number of FTEs used by Trubion in such Calendar Quarter in
               performing Trubion's obligations under the Research Program.
               Except as approved in writing in advance by Wyeth, Wyeth shall
               not be obligated to reimburse Trubion for amounts in excess of
               the applicable budgeted amounts in the Research Budget.

          3.6.3. RECORDS AND AUDITS. During the Research Term, Trubion shall
               keep books and accounts of record in connection with the expenses
               reimbursable under Section 3.6.1 hereof in accordance with GAAP
               and in sufficient detail to permit accurate determination of all
               figures necessary for verification of costs to be reimbursed
               hereunder. Trubion shall maintain such cost records for a period
               of at least three (3) years after the end of the calendar year in
               which they were generated in order to enable audit of such
               records as set forth below. Upon thirty (30) days prior written
               notice from Wyeth, Trubion shall permit an independent certified
               public accounting firm of nationally recognized standing selected
               by Wyeth and reasonably acceptable to Trubion, to examine, at
               Wyeth's sole expense, the relevant books and records of Trubion
               as may be reasonably necessary to verify the amount of
               reimbursable out-of-pocket expenses incurred. An examination by
               Wyeth under this Section 3.6.3 shall occur not more than once in
               any calendar year and shall be limited to the pertinent books and
               records for any calendar year ending not more than thirty six
               (36) months before the date of the request. The accounting firm
               shall be provided access to such books and records at Trubion's
               facility(ies) where such books and records are normally kept and
               such examination shall be conducted during Trubion's normal
               business hours. Trubion may require the accounting firm to sign a
               standard non-disclosure agreement before providing the accounting
               firm access to Trubion's facilities or records. The accounting
               firm shall provide both Trubion and Wyeth a written report
               disclosing whether the certificates and invoices submitted by
               Trubion under Section 3.6.2 are correct or incorrect and the
               specific details concerning any discrepancies. No other
               information shall be provided to Wyeth. If the accounting firm
               determines that the

                                                                              30

<PAGE>

               aggregate amount of out-of-pocket expenses actually incurred by
               Trubion was less than the amount reimbursed by Wyeth during the
               period covered by the audit, Trubion shall refund the excess
               payments to Wyeth within thirty (30) days of its receipt of the
               auditor's report so concluding (or, if later, within fifteen (15)
               days after resolution of a bona fide objection by Trubion to the
               findings in such report). If the amount to be refunded exceeds
               more than ten percent (10%) of the amount that was properly
               payable, Trubion shall reimburse Wyeth for the cost of the audit.
               All information of Trubion which is subject to review under this
               Section 3.6.3 shall be deemed to be Confidential Information of
               Trubion subject to the provisions of Article 7, and such
               Confidential Information shall not be disclosed to any Third
               Party or used for any purpose other than verifying the
               information provided by Trubion to Wyeth; provided, however, that
               such Confidential Information may be disclosed to Third Parties
               only to the extent necessary to enforce Wyeth's rights under this
               Agreement, as may be necessary for Wyeth to exercise its rights
               under this Agreement, or as otherwise expressly permitted under
               this Agreement.

     3.7. DATA AND DELIVERABLES. During the Research Term, each Party will use
          Commercially Reasonable Efforts to promptly provide to the other Party
          the data or desired deliverables specified in the Research Plan,
          including, without limitation, (a) SMIPs, Recombinant DNA, and Cell
          Lines, to the extent related to Licensed Targets and/or Licensed
          Products, (b) activity evaluation of the items listed in (a) obtained
          from in vitro or in vivo assays, pharmacology studies, process
          development data, drug product formulation data, toxicology and safety
          studies, and evaluation of chemotherapy conjugates, but only to the
          extent and in the manner that items listed in (a) and (b) are set
          forth in the Research Plan. Each Party shall also disclose to the
          other Party in writing all data, information, inventions, techniques
          and discoveries (whether patentable or not) arising out of the conduct
          of the Research Program. Disclosure of all such aforementioned
          inventions and discoveries shall be delivered to the other Party in a
          manner mutually agreed upon by the Joint Patent Committee. Subject to
          the terms and conditions of this Agreement, each Party shall have the
          right to use any data or information generated under the Research
          Program for its permitted activities under the Research Program and
          this Agreement (collectively, "Research Program Data"). TRUBION MAKES
          NO REPRESENTATION OR WARRANTY, EITHER EXPRESS OR IMPLIED, THAT IT WILL
          BE ABLE TO SUCCESSFULLY DISCOVER, DEVELOP OR DELIVER ANY SMIP DIRECTED
          AGAINST A LICENSED TARGET OR ANY LICENSED PRODUCT.

     3.8. ALLIANCE MANAGERS. Each Party shall designate a single alliance
          manager, who shall perform such duties relating to the day-to-day
          worldwide

                                                                              31

<PAGE>

          coordination of the collaboration contemplated by this Agreement as
          are determined by the JRC and the JDC. Such alliance managers shall
          have experience and knowledge appropriate for managers with such
          project management responsibilities. Such alliance managers may
          attend, as non-voting members, any meetings of the committees
          contemplated by this Agreement as deemed fit by such committees. Each
          Party may change its designated alliance manager from time to time
          upon notice to the other Party.

4.   PRODUCT DEVELOPMENT, MANUFACTURING, COMMERCIALIZATION AND REGULATORY
     MATTERS.

     4.1. PRODUCT DEVELOPMENT. Except as otherwise expressly provided in
          Articles 2 and 3 hereof and in this Article 4, Wyeth shall have the
          sole authority, at its expense, for the Development of Licensed
          Products, including the initiation and conduct of clinical trials.
          Wyeth shall be responsible for the Development of and shall use its
          Commercially Reasonable Efforts to Develop Licensed Products
          throughout the Territory where it is Commercially Reasonable to do so
          (it being understood that Wyeth shall have the sole discretion to
          select those countries in which it will conduct clinical studies of
          Licensed Products and, when Commercially Reasonable to do so, to delay
          or discontinue the Development of any Licensed Product directed
          against a particular Licensed Target in favor of pursuing Development
          of another Licensed Product directed against such Licensed Target).
          When appropriate based on the data obtained during Development, Wyeth
          shall use its Commercially Reasonable Efforts to secure Regulatory
          Approval for Licensed Products in the Territory.

     4.2. TRANSFER OF PRODUCT DATA AND FILINGS. Upon Wyeth's reasonable request
          and in consultation with the JDC from time to time during the term of
          this Agreement and to the extent permitted by applicable law, Trubion
          shall assign and transfer to Wyeth Trubion's entire right, title and
          interest in and to any of the Product Data and Filings pursuant to an
          instrument to such effect in form and substance reasonably
          satisfactory to Wyeth and shall perform all other actions reasonably
          requested by Wyeth to effect and confirm such transfer. The Parties
          shall cooperate through the JDC to ensure that assignment and transfer
          of Trubion's right, title and interest in and to Product Data and
          Filings relating to CD20 Products is made in a manner that does not
          impede Trubion's activities and responsibilities under Section 4.6.
          After receipt of Wyeth's request consistent with the foregoing,
          Trubion shall provide to Wyeth, at Wyeth's expense, within sixty (60)
          days of receipt of such request, complete copies of such Product Data
          and Filings, including, without limitation, relevant clinical data,
          INDs, additional regulatory filings with FDA or other Regulatory
          Authorities, supplements or amendments thereto, all written
          correspondence with FDA or other Regulatory Authorities regarding the
          regulatory filings, and all

                                                                              32

<PAGE>

          existing written minutes of meetings and memoranda of conversations
          between Trubion (including, to the extent practicable, Trubion's
          investigators) and FDA or other Regulatory Authorities in Trubion's
          possession (or in the possession of any of Trubion's agents and
          subcontractors, such as contract research organizations used by
          Trubion), to the extent Trubion has the right to access and provide to
          Wyeth such Product Data and Filings, regarding such regulatory
          filings, each to the extent they relate to Licensed Products. Within
          thirty (30) days (or such later date as Wyeth may request) after the
          date of receipt of Wyeth's reasonable request after consultation with
          the JDC, Trubion shall execute and deliver a letter to the FDA or
          other Regulatory Authorities, in a form approved by Wyeth,
          transferring ownership to Wyeth of such regulatory filings, if any,
          filed in the name of Trubion that are related to Licensed Products.
          After such transfer of ownership of regulatory filings relating to a
          Licensed Product, during the term of this Agreement all regulatory
          filings with the FDA or other Regulatory Authorities pertaining to
          such Licensed Product shall be made in the name of Wyeth, in
          accordance with the terms of Section 4.3 below.

     4.3. REGULATORY APPROVALS. Wyeth shall have the sole authority to file, in
          its own name, at its sole expense, all Regulatory Approval
          Applications for Licensed Products. Wyeth shall have the sole
          authority and responsibility for communicating with any Regulatory
          Authority regarding any Regulatory Approval Application, or any
          Regulatory Approval once granted. To the extent necessary to satisfy
          applicable regulatory requirements with respect to the INDs for the
          clinical studies of CD20 Products described in Section 4.6, Wyeth
          hereby grants to Trubion a "Right of Reference," as that term is
          defined in 21 C.F.R. Section 314.3(b), to any data Controlled by Wyeth
          that relates to any CD20 Products that are the subject of the clinical
          studies described in Section 4.6 hereof, and Wyeth shall provide a
          signed statement to this effect, if requested by Trubion, in
          accordance with 21 C.F.R. Section 314.50(g)(3). Copies of all Wyeth
          regulatory filings that relate to Trubion's Development activities
          under this Agreement will be provided by Wyeth to Trubion upon
          request, subject to reasonable resource and time constraints.

     4.4. REGULATORY REPORTING. Wyeth shall be responsible for preparing and
          filing all reports required to be filed in order to maintain any
          Regulatory Approvals granted for Licensed Products in the Territory,
          including, without limitation, adverse drug experience reports. To the
          extent Trubion has or receives any information regarding any adverse
          drug experience which may be related to the use of any Licensed
          Product or to Licensed Product Development, Trubion shall promptly
          provide Wyeth with all such information in accordance with the Adverse
          Event Reporting and pharmacovigilance procedures set forth in Exhibit
          4.4 attached hereto (as may be amended from time to time upon written
          mutual agreement of the Parties). From time to time after the
          Effective Date, representatives from

                                                                              33

<PAGE>

          both Parties shall meet to review and revise or replace such Adverse
          Event Reporting and pharmacovigilance procedures.

     4.5. PROGRESS REPORTS.

               (A)  Wyeth shall provide Trubion with confidential summary
                    reports of its and its sublicensees' Development activities,
                    on a Licensed Product-by-Licensed Product basis, on a ***,
                    with respect to CD20 Products and ***, and on an ***, with
                    respect to Other Products. The form of the summary reports,
                    and the type of information and the appropriate and
                    reasonable level of detail to be included in such reports,
                    shall be mutually and reasonably agreed by the Parties;
                    provided that the Parties agree that such reports shall
                    include information regarding progress towards and
                    achievement of any event set forth in Exhibit 5.3 attached
                    hereto.

               (B)  Wyeth shall provide Trubion with confidential summary
                    reports of its and its sublicensees' CD20 Product
                    Commercialization activities on a *** after the First
                    Commercial Sale of a CD20 Product. Beginning *** prior to
                    the anticipated First Commercial Sale of a CD20 Product, and
                    thereafter on a ***, Wyeth shall meet with Trubion and
                    provide updates on CD20 Product Commercialization
                    activities.

               (C)  Wyeth shall provide Trubion with confidential summary
                    reports of its and its sublicensees' *** Commercialization
                    activities on a *** after the First Commercial Sale of a
                    ***. Beginning *** prior to the anticipated First Commercial
                    Sale of a ***, and thereafter on a ***, Wyeth shall meet
                    with Trubion and provide updates on *** Commercialization
                    activities.

               (D)  Wyeth shall provide Trubion with confidential summary
                    reports of its and its sublicensees' Other Product
                    Commercialization activities on an *** after the First
                    Commercial Sale of an Other Product. Beginning *** prior to
                    the anticipated First Commercial Sale of an Other Product,
                    and thereafter on an ***, Wyeth shall meet with Trubion and
                    provide updates on Other Product Commercialization
                    activities.

               (E)  The meetings described in clauses (b) - (d) above shall be
                    coordinated to occur at the same time, to the extent
                    practicable.

                                                                              34

<PAGE>

     4.6. CD20 PRODUCT DEVELOPMENT. Subject to Section 4.7 hereof, Trubion shall
          use its Commercially Reasonable Efforts to conduct the following
          Development activities for CD20 Products: (a) Trubion shall continue
          the Phase I Clinical Studies and Phase IIa Clinical Studies of TRU-015
          ongoing at the Effective Date for treatment of rheumatoid arthritis
          until completion or termination of such studies, including the
          re-treatment periods of such studies; (b) Trubion shall initiate and
          perform the planned Phase IIb Clinical Study of TRU-015 for treatment
          of rheumatoid arthritis through the completion or termination of such
          study; (c) Trubion shall continue the Phase I Clinical Study ongoing
          at the Effective Date, and shall initiate and perform the planned
          Phase III Clinical Studies (or the appropriate subsequent clinical
          study) of TRU-015 for the treatment of *** through the completion or
          termination of such studies; (d) Trubion shall have responsibility for
          and shall perform the clinical studies for at least two (2) additional
          Niche Indications selected by the Parties and set forth in the
          Development Plan; and (e) Trubion shall continue to perform the
          ongoing bioprocess development activities, and in each case (a-e) such
          activities and responsibilities of Trubion shall be performed in
          accordance with the Development Plan. None of the clinical studies
          described in this Section 4.6 shall be terminated prior to completion
          before discussion of such matter by the JDC. Trubion shall keep
          accurate records of its clinical study activities under this Section
          4.6 in accordance with applicable laws and, upon reasonable request,
          shall provide Wyeth with access to such records. Trubion shall
          maintain such records for a period of at least three (3) years after
          the end of the calendar year in which they were generated. The
          Development Plan shall provide that Trubion is responsible for
          conducting the clinical trials for rheumatoid arthritis, *** and
          additional Niche Indications through the completion or termination of
          such clinical studies described above and shall contain a budget for
          such clinical trials. Trubion shall be solely responsible for its
          internal FTE and other internal costs for such Development activities,
          but Wyeth shall reimburse Trubion for all out-of-pocket costs incurred
          by Trubion in connection with the foregoing Development activities in
          accordance with the budget contained in the Development Plan (which
          shall include, without limitation, all expenses paid to one or more
          contract research organizations for such Development activities).
          Trubion shall provide to Wyeth, on or before the first day of each
          Calendar Quarter, a forecast of such out-of-pocket costs (by major
          expense category, on an accrual basis) reimbursable under this Section
          4.6 that Trubion expects to incur during such Calendar Quarter and the
          subsequent three (3) Calendar Quarters, in each case shown by month.
          Reimbursement to be made to Trubion by Wyeth pursuant to this Section
          4.6 will be made pursuant to invoices submitted by Trubion to Wyeth no
          more often than once with respect to any Calendar Quarter, within
          forty-five (45) days of the end of such Calendar Quarter. Payment
          shall be due within forty-five (45) days after Wyeth receives such an
          invoice from Trubion. Each invoice must be accompanied by supporting

                                                                              35

<PAGE>

          documentation sufficiently demonstrating the expense so incurred (such
          as receipts for out-of-pocket expenses). The provisions of Section
          3.6.3 shall apply to the expenses reimbursable by Wyeth under this
          Section 4.6 in the same manner as they apply to expenses reimbursable
          under Section 3.6.1.

     4.7. JOINT DEVELOPMENT COMMITTEE. Within thirty (30) days of the Effective
          Date, Wyeth and Trubion shall establish a CD20 Product Joint
          Development Committee (the "JDC"), comprised of appropriate
          representatives of both Parties, to review and provide input to Wyeth
          regarding CD20 Product Development in the Territory, including the
          strategic direction of the overall CD20 Product Development program.
          Wyeth shall consider in good faith any of Trubion JDC members'
          comments and recommendations regarding CD20 Product Development, but
          Wyeth shall have final decision-making authority with respect to how
          the Parties proceed with CD20 Product Development, subject to Wyeth's
          obligations under Section 4.1 in connection therewith. If Trubion
          disagrees with an action or decision by the JDC, Trubion may express
          its concerns through good faith discussions between the Executive
          Officers of Trubion and Wyeth, with Wyeth Research's President having
          the final decision-making authority with respect to such matter. For
          the avoidance of doubt, the JDC may not impose different or greater
          CD20 Product Development obligations on Trubion than those specified
          in Section 4.6.

     4.8. JOINT PROJECT TEAM; DEVELOPMENT PLAN. Trubion and Wyeth shall form a
          Joint Project Team ("JPT") comprised of appropriate representatives of
          both Parties to plan and implement the CD20 Product Development
          activities in accordance with the Development Plan. The JPT shall
          report to the JDC. If the JPT cannot promptly resolve a disagreement
          or a voting deadlock regarding the CD20 Product Development
          activities, the matter shall be brought before the JDC for resolution.
          Wyeth shall prepare the Development Plan with input and advice from
          Trubion through the JPT. The Development Plan will define each Party's
          roles and responsibilities, provide a mechanism to coordinate each
          Party's and/or joint activities, and provide a process for monthly
          meetings of the JPT to monitor and report on all activities of the
          Parties conducted under the Development Plan. The Development Plan
          shall not impose different or greater CD20 Product Development
          obligations on Trubion than those specified in Section 4.6. The
          Development Plan shall be updated annually by the JPT.

     4.9. MANUFACTURING. Wyeth shall have the exclusive right to Manufacture
          Licensed Products itself or through one or more Third Parties selected
          by Wyeth; provided, however, that Trubion shall use its Commercially
          Reasonable Efforts to Manufacture and supply Wyeth with its
          requirements of the TRU-015 Product in accordance with the Development
          Plan under Trubion's existing contract Manufacturing arrangements for
          use in pre-clinical studies and clinical trials ("Clinical Study
          Supplies"); provided that Trubion cannot guarantee as of the Effective
          Date that it will be able to

                                                                              36

<PAGE>

          Manufacture and supply such requirements. Wyeth shall reimburse
          Trubion for its direct out-of-pocket cost of Clinical Study Supplies,
          including, without limitation, out-of-pocket expenses incurred by
          Trubion prior to the Effective Date that are directly related to the
          Manufacture, testing and release of Clinical Study Supplies to be used
          after the Effective Date (such pre-Effective Date out-of-pocket
          expenses not to exceed ***). Reimbursement of such pre-Effective Date
          expenses shall be due within thirty (30) days after the first patient
          is dosed in the first Phase IIb Clinical Study for rheumatoid
          arthritis using such Clinical Study Supplies. Upon Wyeth's written
          request, Trubion shall provide reasonable assistance to Wyeth, until
          the first cGMP batch of TRU-015 Product is Manufactured in a Wyeth
          facility (or the facility of a Third Party designated by Wyeth), in
          support and facilitation of Wyeth's efforts to Manufacture TRU-015
          Products and to secure appropriate TRU-015 Product Manufacturing
          arrangements with Third Parties. Such assistance shall be at no cost
          to Wyeth; provided that Wyeth shall reimburse Trubion for all of its
          reasonable out-of-pocket expenses related thereto. If applicable, upon
          Wyeth's written request, Trubion shall assign or otherwise transfer to
          Wyeth (to the extent allowable under such agreements) its TRU-015
          Product Manufacturing agreements with Third Parties.

     4.10. COMMERCIALIZATION. Subject to the terms and conditions of this
          Agreement, Wyeth shall have the sole authority and the exclusive right
          to Commercialize Licensed Products itself or through one or more Third
          Parties selected by Wyeth and shall have sole authority and
          responsibility in all matters relating to the Commercialization of
          Licensed Products. Wyeth shall use Commercially Reasonable Efforts to
          Commercialize Licensed Products in the Territory in each country where
          Wyeth has obtained Regulatory Approval for such Licensed Product(s)
          and for each indication of such Licensed Product(s) for which
          Regulatory Approval has been obtained in such country.

     4.11. CO-PROMOTION OPTION. Subject to the foregoing, in the event of a BLA
          filing with the FDA for Regulatory Approval of a CD20 Product for a
          Niche Indication in the United States, Trubion shall have the option
          to Co-Promote the CD20 Product in the United States for such Niche
          Indication in accordance with Wyeth's marketing plan for up to five
          (5) years after the First Commercial Sale of the first CD20 Product
          for any Niche Indication in the United States (the "Co-Promotion
          Period"). The Trubion Co-Promotion option shall be exercisable by
          Trubion giving written notice to Wyeth no later than *** after the
          date of the first BLA filing with the FDA for the first Niche
          Indication for the first CD20 Product (or such longer time as the
          Parties may mutually agree). Promptly after Trubion's exercise of such
          option, the Parties shall negotiate, in good faith, a definitive
          Co-Promotion Agreement, which shall require Trubion and Wyeth to use
          Commercially Reasonable Efforts to Co-Promote such CD20 Product. Such
          Co-Promotion Agreement shall contain customary provisions relating to

                                                                              37

<PAGE>

          relative sales force efforts, responsibility for sales calls, sales
          force training, promotional materials and samples, detailing and the
          number and qualifications of sales force personnel (including medical
          science liaisons) that will be devoted to such Co-Promotion
          activities. The Parties hereby agree, inter alia, that such
          Co-Promotion Agreement, and Wyeth's marketing plan for such CD20
          Product, shall provide (a) Trubion's sales force with a meaningful
          role in the Commercialization of such CD20 Product; (b) that Wyeth
          shall provide CD20 Product-related sales training to Trubion's sales
          force, at no cost to Trubion; and (c) that Trubion's sales force shall
          use CD20 Product promotional materials and samples, to be provided by
          Wyeth at no cost, in connection with their sales efforts. As
          compensation for sales force support provided by Trubion in connection
          with such Co-Promotion, Wyeth shall pay Trubion a fixed fee (to be set
          forth in the definitive Co-Promotion Agreement) for each Product sales
          detail performed by members of Trubion's sales force in accordance
          with Wyeth's marketing plan for such CD20 Product. Trubion will not
          have the right to contract out for or otherwise delegate to any Third
          Party any responsibility for such sales force support. Trubion's sales
          force activities shall be conducted in accordance with Wyeth's
          policies and the marketing and promotion plan for the CD20 Product.

     4.12. CO-PROMOTION COMMITTEE. If Trubion exercises its Co-Promotion option
          with respect to a CD20 Product in accordance with Section 4.11 hereof,
          a Co-Promotion Committee shall be formed by the Parties within thirty
          (30) days after such exercise. The Co-Promotion Committee shall
          oversee all aspects of Co-Promotion-related activities and reasonably
          relevant aspects of Commercialization of such CD20 Product during the
          Co-Promotion Period, and shall include Trubion's Chief Executive
          Officer and Wyeth's Executive Vice President and General Manager,
          Wyeth BioPharma.

     4.13. CO-BRANDING. To the extent allowed by applicable law, all product
          labeling for CD20 Products shall include both Parties' names, which
          shall be of similar size and prominence to the extent practicable
          (except (i) with respect to labeling of vials or other components of a
          CD20 Product that do not include either Party's name or (ii) with
          respect to labeling of diluent or other components packaged together
          with the CD20 Product that do not customarily contain another Person's
          name).

     4.14. MARKING. All Licensed Products shall be marked with the patent
          numbers of issued patents within Trubion Patent Rights and Wyeth
          Patent Rights that cover such Licensed Products, to the extent
          practicable and permitted by law in countries in which such markings
          have notice value against infringers of patents.

5.   CONSIDERATION.

                                                                              38
<PAGE>

     5.1. INITIAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENT. In consideration of
          Trubion's agreement to conduct the Research Program and to participate
          on the JRC and JDC, Wyeth shall pay to Trubion Forty Million Dollars
          ($40,000,000.00) within ten (10) days after the Effective Date, which
          payment shall be non-refundable and non-creditable.

     5.2. EQUITY. Wyeth shall purchase from Trubion common stock of Trubion at
          such time, in such amounts and for such price as specified in the
          Stock Purchase Agreement, attached hereto as Exhibit 5.2A. Concurrent
          with the execution of the Stock Purchase Agreement, the Parties shall
          enter into an amendment of Trubion's Amended and Restated Investor
          Rights Agreement, attached hereto as Exhibit 5.2B.

     5.3. ADDITIONAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENTS. In further
          consideration of Trubion's contributions under the Research Program
          and the Development Program, as provided in Articles 3 and 4 above,
          Wyeth shall pay to Trubion the payments specified in Exhibit 5.3
          attached hereto (each an "Additional Research and Development Expense
          Payment") in the amounts and at such times as specified in Exhibit
          5.3. Wyeth shall notify Trubion promptly upon the achievement of each
          event specified in Exhibit 5.3.

     5.4. ROYALTIES.

          5.4.1. LICENSED PRODUCT ROYALTIES. In consideration for the licenses
               granted to Wyeth under Section 2.1 hereof, and in addition to
               those payments required to be made by Wyeth pursuant to Section
               5.1, Section 5.2 and Section 5.3, Wyeth shall pay to Trubion
               royalties during the Royalty Period as set forth in Sections
               5.4.2, 5.4.3 and 5.4.4 below, subject to the adjustments provided
               in Section 5.4.6 below.

          5.4.2. CD20 PRODUCT ROYALTIES.

               (A)  Except as provided in Sections 5.4.2(b) and 5.4.2(c) below,
                    Wyeth shall pay to Trubion royalties in the amount of the
                    Marginal Royalty Rates (set forth below) of the aggregate
                    Net Sales collectively obtained by Wyeth and its
                    sublicensees from the sale of CD20 Products in the Territory
                    during each calendar year in the applicable Royalty Period:

<TABLE>
<CAPTION>
                              Marginal Royalty Rate
                         (% of the Applicable Portion of
Annual Net Sales Level          Annual Net Sales)
----------------------   -------------------------------
<S>                      <C>
Less than ***                          ***
From ***                               ***
</TABLE>

                                                                              39

<PAGE>

<TABLE>
<S>                      <C>
From ***                               ***
From ***                               ***
Greater than ***                       ***
</TABLE>

                    Each Marginal Royalty Rate set forth in the table above
                    shall apply only to that portion of the annual Net Sales
                    that falls within the indicated range. By way of example
                    only, if the aggregate Net Sales of CD20 Products during a
                    calendar year equaled ***, the total royalty for CD20
                    Products during such year would equal the specified Marginal
                    Royalty Rate (***) of the first *** of Net Sales, plus the
                    specified Marginal Royalty Rate (***) of the next *** of Net
                    Sales, plus the specified Marginal Royalty Rate (***) of the
                    remaining *** of Net Sales (that is, ***, which would equal
                    ***).

                    For purposes of this Section 5.4.2, the "CD20 Effective
                    Royalty Rate" for a particular time period shall mean the
                    weighted average, expressed as a percentage, of the Marginal
                    Royalty Rates that would apply under the provisions of this
                    Section 5.4.2(a) to the aggregate CD20 Product Net Sales in
                    the Territory during such time period (without regard, for
                    these purposes, to any adjustments made under Sections
                    5.4.2(b) or 5.4.2(c)). By way of example only, if the
                    aggregate Net Sales of CD20 Products in the Territory during
                    a calendar year equaled ***, the CD20 Effective Royalty Rate
                    for such calendar year would be calculated as follows: ((***
                    of ***) plus (*** of ***) plus (*** of ***)) divided by ***,
                    expressed as a percentage, which would equal ***. By way of
                    further example only, if the aggregate Net Sales of CD20
                    Products in the Territory during each of the four Calendar
                    Quarters of such calendar year were ***, respectively (for a
                    total of ***), the CD20 Effective Royalty Rates for each of
                    the four Calendar Quarters would be ***, respectively.

               (B)  Subject to the provisions of Section 5.4.2(c) below, in the
                    event that, at any time during the term of the Product
                    License, no issued Valid Claim is included within the
                    Trubion Patent Rights in a country where a CD20 Product is
                    sold (which claim, but for the licenses granted hereunder to
                    Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such
                    CD20 Product in such country), Wyeth shall pay to Trubion
                    royalties with respect to such CD20 Product in such country
                    during such time period, in lieu of the royalties described
                    in Section 5.4.2(a), equal to the

                                                                              40

<PAGE>

                    following amount: (i) the CD20 Effective Royalty Rate of the
                    aggregate Net Sales obtained by Wyeth and its sublicensees
                    from the sale of such CD20 Product in such country during
                    such time period minus (ii) *** of the aggregate Net Sales
                    obtained by Wyeth and its sublicensees from the sale of such
                    CD20 Product in such country during such time period. By way
                    of example only, if the aggregate Net Sales of such a CD20
                    Product in such country during the relevant time period were
                    *** and the CD20 Effective Royalty Rate (based on Net Sales
                    of CD20 Products throughout the Territory) for such time
                    period were ***, the royalties payable under this Section
                    5.4.2(b) on Net Sales in such country would equal (i) ***of
                    ***, (or ***), minus (ii) *** of ***, (or ***), which would
                    equal ***. By way of further example only, if the aggregate
                    Net Sales of such a CD20 Product in such country during the
                    relevant time period were *** and the CD20 Effective Royalty
                    Rate (based on Net Sales of CD20 Products throughout the
                    Territory) for such time period were ***, the royalties
                    payable under this Section 5.4.2(b) on Net Sales in such
                    country would equal (i) *** of ***, (or ***), minus (ii) ***
                    of ***, (or ***), which would equal ***.

               (C)  In the event that at any time during the term of the Product
                    License: (i) no issued Valid Claim is included within the
                    Trubion Patent Rights in a country where a CD20 Product is
                    sold (which claim, but for the licenses granted hereunder to
                    Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such
                    CD20 Product in such country), (ii) a product is sold by a
                    Third Party in such country, which product would, if sold by
                    such Third Party in the United States, infringe an issued
                    Valid Claim included within the Trubion Patent Rights in the
                    United States, and (iii) such product sold by the Third
                    Party has a *** or greater unit market share in such country
                    (where the market is defined as the sum of the unit sales of
                    such CD20 Product and of the product described in clause
                    (ii)), Wyeth shall pay to Trubion royalties with respect to
                    such CD20 Product in such country during such time period,
                    in lieu of the royalties described in Section 5.4.2(a) and
                    Section 5.4.2(b), equal to the following amount: (i) *** of
                    (ii) the CD20 Effective Royalty Rate of the aggregate Net
                    Sales obtained by Wyeth and its sublicensees from the sale
                    of such CD20 Product in such country during such time
                    period. By way of example only, if the aggregate Net Sales
                    of such a CD20 Product in such country during the relevant
                    time period

                                                                              41

<PAGE>

                    were *** and the CD20 Effective Royalty Rate for such time
                    period were ***, the royalties payable under this Section
                    5.4.2(c) would equal (i) *** of (ii) *** of ***, (or ***),
                    which would equal ***.

          5.4.3. ***.

               (A)  Except as provided in Sections 5.4.3(b) and 5.4.3(c) below,
                    Wyeth shall pay to Trubion royalties in the amount of the
                    Marginal Royalty Rates (set forth below) of the aggregate
                    Net Sales collectively obtained by Wyeth and its
                    sublicensees from the sale of each *** in the Territory
                    during each calendar year in the applicable Royalty Period:

<TABLE>
<CAPTION>
                              Marginal Royalty Rate
                         (% of the Applicable Portion of
Annual Net Sales Level          Annual Net Sales)
----------------------   -------------------------------
<S>                      <C>
Less than ***                          ***
From ***                               ***
From ***                               ***
From ***                               ***
Greater than ***                       ***
</TABLE>

                    Each Marginal Royalty Rate set forth in the table above
                    shall apply only to that portion of the annual Net Sales for
                    a particular *** that falls within the indicated range. By
                    way of example only, if the aggregate Net Sales of a ***
                    during a calendar year equaled ***, the total royalty for
                    such *** during such calendar year would equal the specified
                    Marginal Royalty Rate (***) of the first *** of Net Sales,
                    plus the specified Marginal Royalty Rate *** of the next ***
                    of Net Sales, plus the specified Marginal Royalty Rate ***
                    of the remaining *** of Net Sales (that is, ***, which would
                    equal ***).

                    For purposes of this Section 5.4.3, the "*** Royalty Rate"
                    for a particular time period for a particular *** shall mean
                    the weighted average, expressed as a percentage, of the
                    Marginal Royalty Rates that would apply under the provisions
                    of this Section 5.4.3(a) to the Net Sales in the Territory
                    of such *** during such time period (without regard, for
                    these purposes, to any adjustments made under Sections
                    5.4.3(b) or 5.4.3(c)). By way of example only, if the Net
                    Sales of a *** in the Territory during a calendar year
                    equaled***, the *** Royalty Rate for such calendar year for
                    such *** would be calculated as follows: ((***) plus (***)
                    plus (***)) divided by ***, expressed as a

                                                                              42

<PAGE>

                    percentage, which would equal ***. By way of further example
                    only, if the Net Sales of such *** in the Territory during
                    each of the four Calendar Quarters of such calendar year
                    were ***, respectively (for a total of *** in such calendar
                    year), the *** Royalty Rates for each of the four Calendar
                    Quarters would be ***, respectively.

               (B)  Subject to the provisions of Section 5.4.3(c) below, in the
                    event that, at any time during the term of the Product
                    License, no issued Valid Claim is included within the
                    Trubion Patent Rights in a country where a *** is sold
                    (which claim, but for the licenses granted hereunder to
                    Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such ***
                    in such country), Wyeth shall pay to Trubion royalties with
                    respect to such *** in such country during such time period,
                    in lieu of the royalties described in Section 5.4.3(a),
                    equal to the following amount: (i) the *** Royalty Rate for
                    such *** of the aggregate Net Sales obtained by Wyeth and
                    its sublicensees from the sale of such *** in such country
                    during such time period minus (ii) *** of the aggregate Net
                    Sales obtained by Wyeth and its sublicensees from the sale
                    of such *** in such country during such time period. By way
                    of example only, if the aggregate Net Sales of such a *** in
                    such country during the relevant time period were *** and
                    the *** Royalty Rate (based on Net Sales of such ***
                    throughout the Territory) for such time period for such ***
                    were ***, the royalties payable under this Section 5.4.3(b)
                    on Net Sales in such country would equal (i) ***, (or ***),
                    minus (ii) ***, (or ***), which would equal ***. By way of
                    further example only, if the Net Sales of such *** in such
                    country during the relevant time period were *** and the ***
                    Royalty Rate (based on Net Sales of such *** throughout the
                    Territory) for such time period were ***, the royalties
                    payable under this Section 5.4.3(b) on Net Sales in such
                    country would equal (i) ***, (or ***), minus (ii) ***, (or
                    ***), which would equal ***.

               (C)  In the event that at any time during the term of the Product
                    License: (i) no issued Valid Claim is included within the
                    Trubion Patent Rights in any country where a *** is sold
                    (which claim, but for the licenses granted hereunder to
                    Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such ***
                    in such country), (ii) a product is sold by a Third Party in
                    such country, which product would, if sold by such Third
                    Party in the United States, infringe an issued Valid Claim

                                                                              43

<PAGE>

                    included within the Trubion Patent Rights in the United
                    States, and (iii) such product sold by a Third Party has a
                    *** or greater unit market share in such country (where the
                    market is defined as the sum of the unit sales of such ***
                    and of the product described in clause (ii)), Wyeth shall
                    pay to Trubion royalties with respect to such *** in such
                    country during such time period, in lieu of the royalties
                    described in Section 5.4.3(a) and Section 5.4.3(b), equal to
                    the following amount: (i) *** of (ii) the *** Royalty Rate
                    for such *** of the aggregate Net Sales obtained by Wyeth
                    and its sublicensees from the sale of such *** in such
                    country during such time period. By way of example only, if
                    the aggregate Net Sales of such a *** in such country during
                    the relevant time period were *** and the *** Royalty Rate
                    for such time period for such *** were ***, the royalties
                    payable under this Section 5.4.3(c) on Net Sales in such
                    country would equal (i) *** of (ii) *** of ***, (or ***),
                    which would equal ***. By way of further example only, if
                    the Net Sales of such *** in such country during the
                    relevant time period were *** and the *** Royalty Rate
                    (based on Net Sales of such *** throughout the Territory)
                    for such time period were ***, the royalties payable under
                    this Section 5.4.3(c) on Net Sales in such country would
                    equal (i) *** multiplied by (ii) *** of ***, (or ***), which
                    would equal ***.

          5.4.4. OTHER PRODUCT ROYALTIES.

               (A)  Except as provided in Sections 5.4.4(b) and 5.4.4(c) below,
                    Wyeth shall pay Trubion a royalty of *** of the aggregate
                    Net Sales obtained by Wyeth and its sublicensees from the
                    sale of each Other Product in the Territory during each
                    calendar year in the applicable Royalty Period.

               (B)  Subject to the provisions of Section 5.4.4(c) below, in the
                    event that, at any time during the term of the Product
                    License, no issued Valid Claim is included within the
                    Trubion Patent Rights in a country where an Other Product is
                    sold (which claim, but for the licenses granted hereunder to
                    Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such
                    Other Product in such country), Wyeth shall pay to Trubion,
                    with respect to such Other Product in such country during
                    such time period, in lieu of the royalty described in
                    Section 5.4.4(a), a royalty of *** of the aggregate Net
                    Sales obtained by Wyeth and its sublicensees

                                                                              44

<PAGE>

                    from the sale of such Other Product in such country during
                    such time period.

               (C)  In the event that at any time during the term of the Product
                    License: (i) no issued Valid Claim is included within the
                    Trubion Patent Rights in any country where an Other Product
                    is sold (which claim, but for the licenses granted hereunder
                    to Wyeth, would be infringed by Wyeth's or its sublicensees'
                    Manufacture, use, sale, offer for sale or import of such
                    Other Product in such country), (ii) a product is sold by a
                    Third Party in such country, which product would, if sold by
                    such Third Party in the United States, infringe an issued
                    Valid Claim included within the Trubion Patent Rights in the
                    United States, and (iii) such product sold by a Third Party
                    has a *** or greater unit market share in such country
                    (where the market is defined as the sum of the unit sales of
                    such Other Product and of the product described in clause
                    (ii)), Wyeth shall pay to Trubion, with respect to such
                    Other Product in such country during such time period, in
                    lieu of the royalties described in Section 5.4.4(a) and
                    Section 5.4.4(b), a royalty of *** of the aggregate Net
                    Sales obtained by Wyeth and its sublicensees from the sale
                    of such Other Product in such country during such time
                    period.

          5.4.5. EXPIRATION OF ROYALTY PERIOD. After the expiration of the
               Royalty Period for any Licensed Product in any country in the
               Territory, no further royalties shall be payable in respect of
               sales of such Licensed Product in such country and thereafter the
               licenses granted to Wyeth under Section 2.1 with respect to such
               Licensed Product in such country shall be fully paid-up,
               perpetual, irrevocable, royalty-free, exclusive licenses.

          5.4.6. ROYALTY ADJUSTMENTS.

               (A)  CERTAIN THIRD PARTY AGREEMENTS. On a country-by-country
                    basis in a given calendar year, Wyeth shall deduct from CD20
                    Product royalties otherwise payable to Trubion under Section
                    5.4.2 *** of the aggregate amount of royalties actually paid
                    to Third Parties under Additional Third Party Licenses with
                    respect to the Development, Manufacture or Commercialization
                    of CD20 Products in such country in such calendar year;
                    provided, however, that (i) the amount of such deduction
                    shall not exceed *** of the amount of the CD20 Product
                    royalties otherwise payable to Trubion under Section 5.4.2
                    in a given calendar year and (ii) such deduction shall not
                    have the effect, under

                                                                              45

<PAGE>

                    any circumstances, of reducing the CD20 Product royalties
                    payable under Section 5.4.2 below *** of the aggregate Net
                    Sales obtained by Wyeth and its sublicensees from the sale
                    of CD20 Products in such country in a given calendar year
                    (before taking into account the operation of Sections
                    5.4.2(b) and 5.4.2(c)). On a country-by-country basis in a
                    given calendar year, Wyeth shall deduct from *** royalties
                    otherwise payable to Trubion under Section 5.4.3 *** of the
                    aggregate amount of royalties actually paid to Third Parties
                    under Additional Third Party Licenses with respect to the
                    Development, Manufacture or Commercialization of such *** in
                    such country in such calendar year; provided, however, that
                    (i) the amount of such deduction shall not exceed *** of the
                    amount of the *** royalties otherwise payable to Trubion
                    under Section 5.4.3 in a given calendar year and (ii) such
                    deduction shall not have the effect, under any
                    circumstances, of reducing the *** royalties payable under
                    Section 5.4.3 below *** of the aggregate Net Sales obtained
                    by Wyeth and its sublicensees from the sale of such *** in
                    such country in a given calendar year (before taking into
                    account the operation of Sections 5.4.3(b) and 5.4.3(c)).
                    ***

               (B)  OTHER THIRD PARTY AGREEMENTS. Wyeth shall be solely
                    responsible for all payment obligations related to ***.
                    Trubion shall be solely responsible for all payment
                    obligations related to ***.

     5.5. REPORTS AND PAYMENTS.

          5.5.1. CUMULATIVE ROYALTIES. The obligation to pay royalties under
               Section 5.4 of this Agreement shall be imposed only once with
               respect to a single unit of a Licensed Product, regardless of how
               many Valid Claims included within the Trubion Technology would,
               but for this Agreement, be infringed by the Manufacture, use,
               import, offer for sale or sale of such Licensed Product in the
               countr(y)ies of such Manufacture, use or sale. For the avoidance
               of doubt, if a single Licensed Product is both a CD20 Product and
               an Other Product, such Licensed Product shall be deemed to be a
               CD20 Product for purposes of the royalty obligations under
               Section 5.4. If a single Licensed Product is both a *** and an
               Other Product, such Licensed Product shall be deemed to be a ***
               for purposes of the royalty obligations under Section 5.4.

          5.5.2. ROYALTY STATEMENTS AND PAYMENTS. Within *** after the end of
               each Calendar Quarter, Wyeth shall deliver to Trubion a report
               setting forth for such Calendar Quarter the following

                                                                              46

<PAGE>

               information, on a Licensed Product-by-Licensed Product and
               country-by-country basis: (a) the gross sales amount (by Wyeth
               and its sublicensees) for each category of Licensed Product sold
               in the United States and the number of units of Licensed Product
               sold in the United States and other countries in the Territory,
               on a country-by-country basis; (b) the Net Sales for each
               Licensed Product; (c) any adjustments (including the basis
               therefor) made pursuant to Sections 5.4.2(b), 5.4.2(c), 5.4.3(b),
               5.4.3(c), 5.4.4(b), 5.4.4(c) or 5.4.6(a) to the royalty amount
               payable for the sale of each Licensed Product, the applicable
               Marginal Royalty Rates and the CD20 Effective Royalty Rate or ***
               Royalty Rate (as the case may be) payable on the Net Sales, and
               (d) the royalty amount due hereunder for the sale of each
               Licensed Product. No such reports shall be due for any Licensed
               Product before the First Commercial Sale of such Licensed
               Product. The total royalty due for the sale of Licensed Products
               during such Calendar Quarter shall be remitted at the time such
               report is made.

          5.5.3. TAXES AND WITHHOLDING. All payments due Trubion under this
               Agreement will be made without any deduction or withholding for
               or on account of any tax unless such deduction or withholding is
               required by applicable laws or regulations to be assessed against
               Trubion. If Wyeth is so required to deduct or withhold, Wyeth
               will (a) promptly notify Trubion of such requirement, (b) pay to
               the relevant authorities the full amount required to be deducted
               or withheld promptly upon the earlier of determining that such
               deduction or withholding is required or receiving notice that
               such amount has been assessed against Trubion, (c) promptly
               forward to Trubion an official receipt (or certified copy) or
               other documentation reasonably acceptable to Trubion evidencing
               such payment to such authorities, and (d) otherwise reasonably
               cooperate with Trubion in connection with Trubion's attempts to
               obtain favorable tax treatment and credit therefor (where
               appropriate) in accordance with applicable laws.

          5.5.4. CURRENCY. All amounts payable and calculations hereunder shall
               be in United States Dollars. As applicable, Net Sales and any
               royalty deductions shall be translated into United States dollars
               in accordance with Wyeth's customary and usual translation
               procedures, consistently applied, which procedures are in
               accordance with Generally Accepted Accounting Principles in the
               United States.

          5.5.5. ADDITIONAL PROVISIONS RELATING TO ROYALTIES. Trubion
               acknowledges and agrees that nothing in this Agreement
               (including, without limitation, any exhibits or attachments

                                                                              47

<PAGE>

               hereto) shall be construed as representing an estimate or
               projection of either (a) the number of Licensed Products that
               will or may be successfully Developed or Commercialized or (b)
               anticipated sales or the actual value of any Licensed Product and
               that the figures set forth in Section 5.4 or elsewhere in this
               Agreement or that have otherwise been discussed by the Parties
               are merely intended to define Wyeth's royalty obligations to
               Trubion in the event such sales performance is achieved. WYETH
               MAKES NO REPRESENTATION OR WARRANTY, EITHER EXPRESS OR IMPLIED,
               THAT IT WILL BE ABLE TO SUCCESSFULLY DEVELOP OR COMMERCIALIZE ANY
               LICENSED PRODUCT OR, IF COMMERCIALIZED, THAT IT WILL ACHIEVE ANY
               PARTICULAR SALES LEVEL OF SUCH LICENSED PRODUCT(S).

          5.5.6. INTEREST ON PAST DUE PAYMENTS. If either Party fails to pay any
               payment due under this Agreement on or before the date such
               payment is due, as provided in this Agreement, such late payment
               shall bear interest, to the extent permitted by applicable law,
               *** as reported from time to time in The Wall Street Journal,
               effective for the first date on which payment was delinquent and
               calculated on the number of days such payment is overdue or, if
               such rate is not regularly published, as published in such source
               as the Parties agree.

     5.6. MAINTENANCE OF RECORDS; AUDITS.

          5.6.1. RECORD KEEPING. Wyeth shall keep accurate books and accounts of
               record in connection with the sale of Licensed Products, in
               sufficient detail to permit accurate determination of all figures
               necessary for verification of royalties and other payments to be
               paid to Trubion hereunder. Wyeth shall keep accurate records of
               its activities under this Agreement that relate to the events
               with respect to which Additional Research and Development Expense
               Payments may be made under Section 5.3 hereof. Wyeth shall
               maintain such records for a period of at least three (3) years
               after the end of the calendar year in which they were generated.

          5.6.2. AUDITS. Upon thirty (30) days prior written notice from
               Trubion, Wyeth shall permit an independent certified public
               accounting firm of nationally recognized standing selected by
               Trubion and reasonably acceptable to Wyeth, to examine, at
               Trubion's sole expense, the relevant books and records of Wyeth
               as may be reasonably necessary to verify the accuracy of the
               reports submitted by Wyeth in accordance with Section 5.5 and the
               payment of royalties hereunder. An examination by Trubion

                                                                              48

<PAGE>

               under this Section 5.6.2 shall occur not more than once in any
               calendar year and shall be limited to the pertinent books and
               records for any calendar year ending not more than three (3)
               years before the date of the request. The accounting firm shall
               be provided access to such books and records at Wyeth's
               facility(ies) where such books and records are normally kept and
               such examination shall be conducted during Wyeth's normal
               business hours. Wyeth may require the accounting firm to sign a
               standard non-disclosure agreement before providing the accounting
               firm access to Wyeth's facilities or records. Upon completion of
               the audit, the accounting firm shall provide both Wyeth and
               Trubion a written report disclosing whether the reports submitted
               by Wyeth are correct or incorrect, whether the royalties paid are
               correct or incorrect, and in each case, the specific details
               concerning any discrepancies. No other information shall be
               provided to Trubion.

          5.6.3. UNDERPAYMENTS/OVERPAYMENTS. If such accounting firm concludes
               that additional royalties were due to Trubion, Wyeth shall pay to
               Trubion the additional royalties within thirty (30) days of the
               date Wyeth receives such accountant's written report so
               concluding. If such royalty underpayment exceeds ten percent
               (10%) of the royalties that were to be paid to Trubion, Wyeth
               also shall reimburse Trubion for the out-of-pocket expenses
               incurred in conducting the audit. If such accounting firm
               concludes that Wyeth overpaid royalties to Trubion, Trubion,
               within thirty (30) days of the date Trubion receives such
               account's report so concluding, will refund such overpayments to
               Wyeth less the reasonable out-of-pocket costs incurred by Trubion
               in conducting the audit.

          5.6.4. CONFIDENTIALITY. All financial information of Wyeth which is
               subject to review under this Section 5.6 shall be deemed to be
               Wyeth's Confidential Information subject to the provisions of
               Article 7 hereof, and Trubion shall not disclose such
               Confidential Information to any Third Party or use such
               Confidential Information for any purpose other than verifying
               payments to be made by Wyeth to Trubion hereunder; provided,
               however, that such Confidential Information may be disclosed by
               Trubion to Third Parties only to the extent necessary to enforce
               Trubion's rights under this Agreement.

6. INTELLECTUAL PROPERTY.

     6.1. INVENTIONS; JOINT PATENT COMMITTEE.

                                                                              49
<PAGE>

          6.1.1. OWNERSHIP AND INVENTORSHIP. A Party shall own all inventions
               and Know-How made solely by employees of such Party, and shall
               jointly own with the other Party any invention, whether or not
               patentable, made jointly by employees of both Parties (a "Joint
               Invention"), all Joint Patent Rights directed thereto, and any
               Know-How made jointly by employees of both Parties ("Joint
               Know-How"). All determinations of inventorship under this
               Agreement shall be made in accordance with United States patent
               law. Each Party shall disclose promptly in writing to the other
               any Joint Inventions and any candidate Joint Inventions of which
               it becomes aware. Subject to (a) the grant of licenses to Wyeth
               under Section 2.1 and to Trubion under Section 2.2, (b) the
               exclusivity provisions of Section 2.3, and (c) the Parties' other
               rights and obligations under this Agreement, each Party shall be
               free to exploit (including to research, Develop, Manufacture,
               Commercialize and enforce), either itself or through the grant of
               licenses to Third Parties (which Third Party licenses are further
               sublicensable), Joint Patent Rights and Joint Know-How throughout
               the world without restriction, without the need to obtain further
               consent from the other Party, and without payment of any
               compensation to the other Party.

          6.1.2. SMIP IMPROVEMENTS. All SMIP Improvements made by Wyeth, whether
               independently or jointly with Trubion, in the course of
               performing Wyeth's obligations under this Agreement during the
               term of the Agreement (each, a "Covered SMIP Improvement") shall
               be promptly disclosed by Wyeth to Trubion. Wyeth, subject to the
               rights and licenses granted by Trubion to Wyeth hereunder, hereby
               grants to Trubion a worldwide, royalty-free (other than as
               expressly set forth in this Section 6.1.2), irrevocable,
               non-exclusive license (with the right to sublicense), under
               Wyeth's rights to such Covered SMIP Improvements, to practice,
               exploit and use such Covered SMIP Improvements in connection with
               the research, Manufacture, Development, Commercialization or use
               of SMIPs (***); provided, however, for the avoidance of doubt,
               that the license granted to Trubion pursuant to this sentence
               shall not be deemed to constitute or include a license with
               respect to any underlying Wyeth technology or any Wyeth
               Technology (including without limitation Manufacturing, delivery,
               formulation and conjugation technology) other than Wyeth's rights
               to such Covered SMIP Improvements. In the event, and to the
               extent, that Wyeth is obligated to pay a Third Party any
               royalties or other payments as a result of the licensing of a
               Covered SMIP Improvement to Trubion pursuant to this Section
               6.1.2 or as a result of Trubion's or its sublicensees' (excluding
               Wyeth's) practice of such Covered SMIP Improvement, the license
               by Wyeth to Trubion pursuant to this Section 6.1.2 with respect
               to

                                                                              50

<PAGE>

               such Covered SMIP Improvement shall be conditioned on Trubion's
               continuing obligation to pay Wyeth the amount of such royalties
               and other payments according to the terms of the applicable
               agreement between Wyeth and such Third Party. In the event that
               Trubion grants a sublicense to any Third Party with respect to a
               Covered SMIP Improvement that is not a Joint Invention (but
               rather was invented solely by Wyeth), Trubion shall pay Wyeth a
               royalty of *** of the net sales by such sublicensee (or its
               affiliates or sublicensees) of any product that incorporates such
               Covered SMIP Improvement. For purposes of the preceding sentence,
               "net sales" shall be defined in a manner substantially similar to
               the definition of "Net Sales" under this Agreement.

          6.1.3. JOINT PATENT COMMITTEE.

               (A)  ESTABLISHMENT; MEETINGS; DECISIONS. Within thirty (30) days
                    after the Effective Date, the Parties shall establish a
                    Joint Patent Committee composed of at least one (1)
                    representative from each Party with experience in the
                    prosecution of biotechnology patents. The Joint Patent
                    Committee will have such duties and responsibilities as are
                    expressly assigned to it under this Article 6. The Joint
                    Patent Committee shall meet as soon as practicable after it
                    is established by the Parties and, thereafter, at such
                    additional times as the Parties deem appropriate, not less
                    frequently than quarterly. The meetings of the Joint Patent
                    Committee shall alternate between the Parties' business
                    locations or as otherwise decided by the Joint Patent
                    Committee; provided that Joint Patent Committee meetings may
                    be conducted in person, by telephone or by videoconference.
                    Each Party shall use reasonable efforts to cause its
                    representative(s) to attend each Joint Patent Committee
                    meeting. Decisions of the Joint Patent Committee shall be
                    made by unanimous consent, with each Party having one vote.
                    The Joint Patent Committee may act without a meeting if an
                    action by unanimous written consent is signed by each
                    committee member. If the Joint Patent Committee is unable to
                    reach agreement on a matter for which it has decision-making
                    authority pursuant to Section 6.1.3(b), 6.2.1(c) or
                    6.2.2(c), the matter may be referred, at the request of
                    either Party, for resolution by outside patent counsel
                    mutually selected by the Parties (wherein such outside
                    patent counsel shall be knowledgeable and experienced in the
                    subject matter of the matter so referred), and such
                    resolution shall be deemed the decision of the Joint Patent
                    Committee. Unless otherwise agreed by the Parties, the
                    patent counsel selected will not

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                    have served as primary outside IP counsel to either Party
                    prior to being selected to resolve the Joint Patent
                    Committee disagreement. ***

               (B)  CATEGORY 1 COVERED SMIP IMPROVEMENTS AND CATEGORY 2 COVERED
                    SMIP IMPROVEMENTS. Without limiting Wyeth's obligation under
                    Section 6.1.1 and Section 6.1.2 to disclose promptly to
                    Trubion any inventions and candidate inventions made
                    hereunder (including, without limitation, any Covered SMIP
                    Improvements), each Party shall report on a quarterly basis
                    to the Joint Patent Committee whether any of its activities
                    hereunder during the prior Calendar Quarter involved a new
                    Covered SMIP Improvement. The Joint Patent Committee shall
                    decide whether a given Covered SMIP Improvement (i) is
                    solely applicable to SMIP coding regions (a "Category 1
                    Covered SMIP Improvement"), or (ii) is not solely applicable
                    to SMIP coding regions (a "Category 2 Covered SMIP
                    Improvement"). ***.

     6.2. PATENT RIGHTS.

          6.2.1. FILING, PROSECUTION AND MAINTENANCE OF PATENT RIGHTS.

               (A)  TRUBION PATENT RIGHTS.

                    (I)  TRUBION PATENT RIGHTS. Trubion shall use its
                         Commercially Reasonable Efforts to prepare, file,
                         prosecute and maintain, throughout the Territory, all
                         of the Trubion Patent Rights, using patent counsel of
                         Trubion's choice; provided, however, that Trubion shall
                         give Wyeth before filing a reasonable opportunity to
                         review and comment upon the text of any applications
                         for Trubion Patent Rights to the extent related to any
                         Licensed Product, any SMIPs directed against any
                         Licensed Target, or the Development, Manufacture, use
                         or Commercialization thereof (collectively,
                         "Product-Related Patent Rights"); and provided further,
                         however, that patent counsel for patent applications
                         for Product-Related Patent Rights that are prepared or
                         filed on or after the Signing Date and that do not rely
                         on the priority date of a patent or patent application
                         filed before the Signing Date will be mutually agreed
                         upon by the Parties. Trubion shall reasonably consider
                         and address Wyeth's comments on patent applications
                         included in Product-Related

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<PAGE>

                         Patent Rights. Trubion shall consult with Wyeth with
                         respect to such patent applications, and shall supply
                         Wyeth with a copy of such patent applications as filed,
                         together with notice of each filing date and serial
                         number. Trubion shall also keep Wyeth advised of the
                         status of prosecution of all such patent applications
                         included in the Product-Related Patent Rights, and
                         shall consult with Wyeth and provide Wyeth with a
                         reasonable opportunity to comment on all correspondence
                         received from and all submissions to be made to any
                         government patent office or authority with respect to
                         any such patent application or patent. Trubion shall
                         reasonably consider and address Wyeth's comments on
                         such correspondence and submissions. Each Party shall
                         be responsible for *** of Trubion's out-of-pocket
                         expenses incurred in connection with preparing, filing,
                         prosecuting and maintaining such Product-Related Patent
                         Rights throughout the Territory, including, but not
                         limited to, out-of-pocket expenses for inventorship
                         determinations and inventorship disputes (other than
                         between the Parties); provided, however, that in the
                         event Trubion grants a license(s) in a given country or
                         countries to one or more Third Parties under any patent
                         application or patent that is included in the
                         Product-Related Patent Rights, Wyeth shall be
                         responsible for a pro rata portion, based on a total
                         number of parties that includes Trubion, Wyeth and all
                         Third Party licensees under such patent application or
                         patent (e.g., if there are two (2) Third Party
                         licensees in addition to Wyeth and Trubion, then Wyeth
                         shall be responsible for twenty-five percent (25%)), of
                         Trubion's out-of-pocket expenses incurred in a given
                         country in connection with preparing, filing,
                         prosecuting and maintaining such patent application or
                         patent. (As used in this Article 6, "out-of-pocket
                         expenses" shall be deemed to include, without
                         limitation, reasonable attorneys' fees.) Wyeth shall
                         reimburse Trubion on a quarterly basis within *** of
                         receiving an invoice accompanied by supporting
                         documentation demonstrating the out-of-pocket expenses
                         so incurred. On an annual basis, during the last
                         Calendar Quarter of each year, Trubion shall provide
                         Wyeth with a good faith, written estimate

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<PAGE>

                         of the out-of-pocket expenses reimbursable by Wyeth
                         under this Section 6.2.1(a) that Trubion expects to
                         incur in the following calendar year. In addition, if
                         Trubion elects not to file a patent application on
                         Trubion Know-How that, if filed, would be a
                         Product-Related Patent Right, or to cease the
                         prosecution and/or maintenance of any Product-Related
                         Patent Rights, (except for abandonment of a patent
                         application in favor of a patent application
                         subsequently filed for purposes of continuing the
                         prosecution of Patent Rights claiming the inventions
                         included in the abandoned patent application), Trubion
                         shall provide Wyeth with written notice immediately
                         upon the decision to not file or continue the
                         prosecution of such patent application or maintenance
                         of such patent. In such event, Trubion shall permit
                         Wyeth, at Wyeth's sole discretion, to file and/or
                         continue prosecution and/or maintenance of such
                         Product-Related Patent Right on Trubion's behalf and at
                         Wyeth's own expense. If Wyeth elects to file or to
                         continue such prosecution or maintenance, it shall
                         notify Trubion in writing of such decision within ***
                         of receipt of Trubion's written notice, in which case
                         Trubion shall assign to Wyeth such Product-Related
                         Patent Right abandoned by Trubion and shall execute
                         such documents and perform such acts, at Wyeth's
                         expense, as may be reasonably necessary to permit Wyeth
                         to file, prosecute and/or maintain such Product-Related
                         Patent Right. In the event that Wyeth files or
                         continues the prosecution or maintenance of any such
                         Product-Related Patent Right pursuant to this Section
                         6.2.1(a), then Wyeth shall no longer be obligated to
                         pay to Trubion any royalty payments that would be due
                         solely with respect to such Product-Related Patent
                         Right.

               (B)  WYETH PATENT RIGHTS. Subject to Section 6.2.1(d), and except
                    with respect to Covered SMIP Improvements, Wyeth, at its own
                    expense, shall have the sole right, but not the obligation,
                    to prepare, file, prosecute and maintain, throughout the
                    Territory, all Wyeth Patent Rights, using patent counsel of
                    Wyeth's choice.

               (C)  JOINT PATENT RIGHTS. Subject to Section 6.2.1(d), in the
                    event the Parties make any Joint Invention (excluding a
                    Covered SMIP Improvement), the Joint Patent Committee

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<PAGE>

                    shall promptly meet to discuss and determine whether to seek
                    patent protection thereon. If the Joint Patent Committee
                    decides to seek patent protection on such Joint Invention,
                    then Wyeth shall have the primary obligation to prepare,
                    file, prosecute and maintain any corresponding Joint Patent
                    Rights throughout the Territory using patent counsel
                    mutually agreeable to the Parties, such agreement not to be
                    unreasonably withheld. Wyeth shall give Trubion a reasonable
                    opportunity to review and comment on the text of any patent
                    application with respect to such Joint Patent Right before
                    filing, shall consult with Trubion with respect thereto,
                    shall reasonably consider and address any of Trubion's
                    comments, and shall supply Trubion with a copy of each such
                    patent application as filed, together with notice of its
                    filing date and serial number. Wyeth shall keep Trubion
                    advised of the status of the actual and prospective patent
                    filings (including, without limitation, the grant of any
                    Joint Patent Rights), shall provide Trubion with a
                    reasonable opportunity to comment on all correspondence
                    received from and all proposed submissions to be made to any
                    government patent office or authority related to the filing,
                    prosecution and maintenance of such patent filings, shall
                    consult with Trubion with respect thereto, and shall
                    reasonably consider and address any of Trubion's comments on
                    such correspondence and submissions. Trubion shall reimburse
                    Wyeth for *** of the out-of-pocket expenses incurred by
                    Wyeth in connection with preparing, filing, prosecuting and
                    maintaining such Joint Patent Rights (other than
                    out-of-pocket expenses for inventorship determinations and
                    inventorship disputes), which reimbursement will be made
                    within *** of receiving invoices, such invoices to be
                    submitted by Wyeth no more often than once per Calendar
                    Quarter and to be accompanied by supporting documentation
                    demonstrating and detailing the expenses so incurred. On an
                    annual basis, during the last Calendar Quarter of each year,
                    Wyeth shall provide Trubion with a good faith, written
                    estimate of the out-of-pocket expenses reimbursable by
                    Trubion under this Section 6.2.1(c) that Wyeth expects to
                    incur in the following calendar year. If Wyeth elects not to
                    file a patent application on any such Joint Patent Rights,
                    or to cease the prosecution and/or maintenance of any such
                    Joint Patent Rights (except for abandonment of a patent
                    application in favor of a patent application subsequently
                    filed for purposes of continuing the prosecution of Patent
                    Rights claiming the inventions included in the abandoned
                    patent

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<PAGE>

                    application), Wyeth shall provide Trubion with written
                    notice immediately upon the decision to not file or continue
                    the prosecution of such patent application or maintenance of
                    such patent. In such event, Wyeth shall permit Trubion, at
                    Trubion's sole discretion, to file and/or continue
                    prosecution and/or maintenance of such Joint Patent Rights
                    at Trubion's own expense. If Trubion elects to continue such
                    prosecution or maintenance, it shall notify Wyeth in writing
                    of such decision within *** of receipt of Wyeth's written
                    notice, in which case, Wyeth shall assign to Trubion such
                    Joint Patent Rights abandoned by Wyeth and shall execute
                    such documents and perform such acts, at Trubion's expense,
                    as may be reasonably necessary to permit Trubion to file,
                    prosecute and/or maintain such Joint Patent Rights.

               (D)  CATEGORY 1 AND CATEGORY 2 COVERED SMIP IMPROVEMENTS.

                    (I)  CATEGORY 1 COVERED SMIP IMPROVEMENTS. In the event that
                         Wyeth makes any Category 1 Covered SMIP Improvement
                         (whether it is an invention solely by Wyeth or a Joint
                         Invention), Trubion shall have the first right and
                         primary obligation to prepare, file, prosecute and
                         maintain any Patent Rights covering such Category 1
                         Covered SMIP Improvement, using patent counsel mutually
                         agreeable to the Parties, such agreement not to be
                         unreasonably withheld. Trubion shall give Wyeth a
                         reasonable opportunity to review and comment on the
                         text of any patent application with respect to such
                         Category 1 Covered SMIP Improvement before filing,
                         shall consult with Wyeth with respect thereto, shall
                         reasonably consider and address any of Wyeth's
                         comments, and shall supply Wyeth with a copy of the
                         patent application as filed, together with notice of
                         its filing date and serial number. Trubion shall keep
                         Wyeth advised of the status of the actual and
                         prospective patent filings (including, without
                         limitation, the grant of any Patent Rights covering
                         such Category 1 Covered SMIP Improvements), shall
                         provide Wyeth with a reasonable opportunity to comment
                         on all correspondence received from and all proposed
                         submissions to be made to any government patent office
                         or authority related to the filing, prosecution and
                         maintenance of such patent filings, shall consult with
                         Wyeth with respect thereto, and shall reasonably
                         consider and

                                                                              56

<PAGE>

                         address any of Wyeth's comments on such correspondence
                         and submissions. Each Party shall be responsible for
                         *** of Trubion's out-of-pocket expenses incurred in
                         connection with preparing, filing, prosecuting and
                         maintaining such Category 1 Covered SMIP
                         Improvement-related Patent Rights throughout the
                         Territory, other than out-of-pocket expenses for
                         inventorship determinations and inventorship disputes.
                         Wyeth shall reimburse Trubion on a quarterly basis
                         within *** of receiving an invoice accompanied by
                         supporting documentation demonstrating the
                         out-of-pocket expenses so incurred. On an annual basis,
                         during the last Calendar Quarter of each year, Trubion
                         shall provide Wyeth with a good faith, written estimate
                         of the out-of-pocket expenses reimbursable by Wyeth
                         under this Section 6.2.1(d)(i) that Trubion expects to
                         incur in the following calendar year. In addition, if
                         Trubion elects not to file a patent application on a
                         Category 1 Covered SMIP Improvement, or to cease the
                         prosecution and/or maintenance of any Category 1
                         Covered SMIP Improvement-related Patent Right (except
                         for abandonment of a patent application in favor of a
                         patent application subsequently filed for purposes of
                         continuing the prosecution of Patent Rights claiming
                         the inventions included in the abandoned patent
                         application), Trubion shall provide Wyeth with written
                         notice immediately upon the decision to not file or
                         continue the prosecution of such patent application or
                         maintenance of such patent. If Wyeth elects to continue
                         such prosecution or maintenance, it shall notify
                         Trubion in writing of such decision within *** of
                         receipt of Trubion's written notice, in which case
                         Trubion shall assign to Wyeth the right to file,
                         prosecute and maintain such Category 1 Covered SMIP
                         Improvement-related Patent Right, and shall execute
                         such documents and perform such acts, at Wyeth's
                         expense, as may be reasonably necessary to permit Wyeth
                         to file, prosecute and/or maintain such Category 1
                         Covered SMIP Improvement-related Patent Right. In the
                         event that Wyeth continues the prosecution or
                         maintenance of any Category 1 Covered SMIP
                         Improvement-related Patent Right pursuant to this
                         Section 6.2.1(d)(i), Wyeth shall do so at its own
                         expense, and Wyeth shall no longer be obligated to pay
                         to Trubion any royalty payments that would be due
                         solely with respect to any

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<PAGE>

                         such Category 1 Covered SMIP Improvement-related Patent
                         Right.

                    (II) CATEGORY 2 COVERED SMIP IMPROVEMENTS. In the event that
                         Wyeth makes any Category 2 Covered SMIP Improvement
                         (whether it is an invention solely by Wyeth or a Joint
                         Invention), Wyeth shall have the first right and
                         primary obligation to prepare, file, prosecute and
                         maintain any Patent Rights covering such Category 2
                         Covered SMIP Improvement, at its own expense, using
                         patent counsel mutually agreeable to the Parties, such
                         agreement not to be unreasonably withheld. Wyeth shall
                         give Trubion a reasonable opportunity to review and
                         comment on the text of any patent application with
                         respect to such Category 2 Covered SMIP Improvement
                         before filing, shall consult with Trubion with respect
                         thereto, shall reasonably consider and address any of
                         Trubion's comments, and shall supply Trubion with a
                         copy of the patent application as filed, together with
                         notice of its filing date and serial number. Wyeth
                         shall keep Trubion advised of the status of the actual
                         and prospective patent filings (including, without
                         limitation, the grant of any Patent Rights covering
                         such Category 2 Covered SMIP Improvement), shall
                         provide Trubion with a reasonable opportunity to
                         comment on all correspondence received from and all
                         proposed submissions to be made to any government
                         patent office or authority related to the filing,
                         prosecution and maintenance of such patent filings,
                         shall consult with Trubion with respect thereto, and
                         shall reasonably consider and address any of Trubion's
                         comments on such correspondence and submissions. If
                         Wyeth elects not to file a patent application on a
                         Category 2 Covered SMIP Improvement, or to cease the
                         prosecution and/or maintenance of any Category 2
                         Covered SMIP Improvement-related Patent Right (except
                         for abandonment of a patent application in favor of a
                         patent application subsequently filed for purposes of
                         continuing the prosecution of Patent Rights claiming
                         the inventions included in the abandoned patent
                         application), Wyeth shall provide Trubion with written
                         notice immediately upon the decision to not file or
                         continue the prosecution of such patent application or
                         maintenance of such patent. If Trubion elects to
                         continue such prosecution or maintenance, it shall
                         notify Wyeth in writing of such

                                                                              58

<PAGE>

                         decision within *** of receipt of Wyeth's written
                         notice, in which case Wyeth shall assign to Trubion
                         such Category 2 Covered SMIP Improvement-related Patent
                         Right abandoned by Wyeth and shall execute such
                         documents and perform such acts, at Trubion's expense,
                         as may be reasonably necessary to permit Trubion to
                         file, prosecute and/or maintain such Category 2 Covered
                         SMIP Improvement-related Patent Right.

          6.2.2. ENFORCEMENT OF PATENT RIGHTS.

               (A)  NOTICE. If either Wyeth or Trubion becomes aware of any
                    infringement, anywhere in the Territory, of any issued
                    patent within the Trubion Patent Rights (including
                    Product-Related Patent Rights), Wyeth Patent Rights or Joint
                    Patent Rights, which infringing activity adversely affects
                    or is reasonably expected to adversely affect any SMIP or
                    Licensed Product hereunder, it will promptly notify the
                    other Party in writing to that effect and the Parties will
                    consult with each other through the Joint Patent Committee
                    regarding any actions to be taken with respect to such
                    infringing activity; provided, however, that neither Party
                    is obligated to disclose confidential information of a Third
                    Party (other than a sublicensee under this Agreement, to the
                    extent such Party is permitted to do so under the terms of
                    the sublicense).

               (B)  PRODUCT-RELATED PATENT RIGHTS. To the extent permitted under
                    the Trubion Third Party Agreements, if applicable, Wyeth
                    shall have the first right, but not the obligation, to take
                    action to obtain a discontinuance of infringement or bring
                    suit against a Third Party infringer of Product-Related
                    Patent Rights under which Wyeth has an exclusive license to
                    make, use and sell Licensed Products under this Agreement,
                    to the extent such infringement involves a product directed
                    against a Licensed Target. Wyeth shall have such first right
                    within three (3) months from the date of notice and the
                    right to join Trubion as a party plaintiff. Wyeth shall be
                    responsible for, and shall bear, all the out-of-pocket
                    expenses of any suit brought by it claiming infringement of
                    any such Product-Related Patent Rights; provided that
                    Trubion shall reimburse Wyeth for *** of the out-of-pocket
                    expenses incurred in connection therewith. Trubion will
                    cooperate with Wyeth in any such suit and shall have the
                    right to consult with Wyeth and to participate in and be
                    represented by independent counsel in such

                                                                              59

<PAGE>

                    litigation at its own expense. Wyeth shall incur no
                    liability to Trubion as a consequence of such litigation or
                    any unfavorable decision resulting therefrom, including any
                    decision holding any of the Product-Related Patent Rights
                    invalid or unenforceable. Any recoveries obtained by Wyeth
                    as a result of any proceeding against such Third Party
                    infringer shall be allocated as follows:

                    (I)  Such recovery shall first be used to reimburse each
                         Party for all out-of-pocket litigation expenses in
                         connection with such litigation paid by that Party; and

                    (II) With respect to any remaining recovery, *** shall go to
                         Wyeth and *** shall go to Trubion.

                    If, after the expiration of the three (3) month period (or,
                    if earlier, the date upon which Wyeth provides written
                    notice that it does not plan to bring suit), Wyeth has not
                    obtained a discontinuance of such infringement of
                    Product-Related Patent Rights or filed suit against any such
                    Third Party infringer hereunder, then Trubion shall have the
                    right, but not the obligation, to bring suit against such
                    Third Party infringer of the Product-Related Patent Rights
                    under which Wyeth has an exclusive license under this
                    Agreement, provided that each Party shall bear *** of the
                    out-of-pocket expenses of such suit. Wyeth will cooperate
                    with Trubion in any such suit for infringement of such
                    Product-Related Patent Rights brought by Trubion against a
                    Third Party, and shall have the right to consult with
                    Trubion and to participate in and be represented by
                    independent counsel in such litigation at its own expense.
                    Trubion shall incur no liability to Wyeth as a consequence
                    of such litigation or any unfavorable decision resulting
                    therefrom, including any decision holding any of the
                    Product-Related Patent Rights invalid or unenforceable. Any
                    recoveries obtained by Trubion as a result of any such
                    proceeding against a Third Party infringer shall be
                    allocated as follows:

                    (III) Such recovery shall first be used to reimburse each
                         Party for all out-of-pocket litigation expenses in
                         connection with such litigation paid by that Party; and

                    (IV) With respect to any remaining recovery, *** shall go to
                         Trubion.

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<PAGE>

               (C)  JOINT PATENT RIGHTS. With respect to any notice of a Third
                    Party infringer of the Joint Patent Rights, the Joint Patent
                    Committee shall meet as soon as reasonably practicable to
                    discuss such infringement and determine an appropriate
                    course of action. Wyeth shall have the first right but not
                    the obligation to bring an action against such Third Party
                    infringer or otherwise address such alleged infringement
                    within *** from the date of notice and to control such
                    litigation or other means of addressing such infringement.
                    Wyeth shall be responsible for, and shall bear, all the
                    out-of-pocket expenses of any suit brought by it claiming
                    infringement of any such Joint Patent Rights; provided that
                    Trubion shall reimburse Wyeth for *** of the out-of-pocket
                    expenses incurred in connection therewith. Trubion shall
                    cooperate with Wyeth, at Wyeth's expense, in any such suit
                    brought by Wyeth and shall have the right to consult with
                    Wyeth and participate in and be represented by independent
                    counsel in such litigation at its own expense. Wyeth shall
                    incur no liability to Trubion as a consequence of such
                    litigation or any unfavorable decision resulting therefrom,
                    including any decision holding any of the Joint Patent
                    Rights invalid or unenforceable. Any recoveries obtained by
                    Wyeth as a result of any proceeding against such Third Party
                    infringer shall be allocated as follows:

                    (I)  Such recovery shall first be used to reimburse each
                         Party for all out-of-pocket litigation expenses in
                         connection with such litigation paid by that Party; and

                    (II) With respect to any remaining recovery, *** shall go to
                         Wyeth and *** shall go to Trubion.

                    If, after the expiration of the three (3) month period (or,
                    if earlier, the date upon which Wyeth provides written
                    notice that it does not plan to bring suit) Wyeth elects not
                    to take action against a Third Party infringer of the Joint
                    Patent Rights and Trubion elects to bring an action, then
                    Wyeth shall cooperate, at Trubion's expense, in such action.
                    Trubion shall incur no liability to Wyeth as a consequence
                    of such litigation or any unfavorable decision resulting
                    therefrom, including any decision holding any of the Joint
                    Patent Rights invalid or unenforceable. Any recoveries
                    obtained by Trubion shall go to Trubion.

          6.2.3. INFRINGEMENT AND THIRD PARTY LICENSES.

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<PAGE>

               (A)  INFRINGEMENT OF THIRD PARTY PATENTS - COURSE OF ACTION. If
                    the research, Development, Manufacture or Commercialization
                    of any Licensed Product is alleged by a Third Party to
                    infringe a Third Party's patent, the Party becoming aware of
                    such allegation shall promptly notify the other Party.

                    Additionally, if either Party determines (with consultation
                    by the Joint Patent Committee) that, based upon the review
                    of a Third Party's patent or patent application or other
                    intellectual property rights, it may be desirable to obtain
                    a license from such Third Party with respect thereto, such
                    Party shall promptly notify the other Party of such
                    determination. In the event Wyeth determines, after good
                    faith consultation with Trubion through the Joint Patent
                    Committee, that it is necessary or useful to obtain licenses
                    under intellectual property rights from Third Parties
                    ("Additional Third Party Licenses") in order to Develop,
                    Manufacture or Commercialize Licensed Products under this
                    Agreement, Wyeth shall be solely responsible for negotiating
                    and obtaining any such Additional Third Party Licenses, but
                    shall not be obligated to do so. Trubion may elect, in its
                    sole discretion, to obtain one or more Third Party licenses
                    that are applicable to Trubion Technology in general but are
                    not Licensed Product-specific ("Trubion Additional Third
                    Party Licenses"); if Trubion so elects, then Trubion shall
                    be solely responsible for negotiating and obtaining any such
                    licenses, but shall not be obligated to do so.

               (B)  THIRD PARTY INFRINGEMENT SUIT. If a Third Party sues a Party
                    (the "Sued Party") alleging that the Sued Party or its
                    Affiliates' or sublicensees' research, Development,
                    Manufacture or Commercialization of any Licensed Product
                    during the term of and pursuant to this Agreement infringes
                    or will infringe said Third Party's patent, then, upon the
                    Sued Party's request and in connection with the Sued Party's
                    defense of any such Third Party infringement suit, the other
                    Party shall provide reasonable assistance to the Sued Party
                    for such defense. If both Wyeth and Trubion are sued by a
                    Third Party, then the Parties shall consult with one another
                    through the Joint Patent Committee. Unless otherwise
                    determined by the Joint Patent Committee, Wyeth will control
                    the defense of any suit relating to Licensed Products
                    (whether one or both Parties are Sued Parties) and shall
                    select counsel for such suit after consultation through the
                    Joint Patent Committee.

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<PAGE>

                    Trubion shall have the right to participate in and be
                    represented by independent counsel in such litigation at its
                    own expense. If the alleged infringement is of claims
                    related to the Trubion Technology utilized by Wyeth
                    hereunder, Wyeth shall be responsible for, and shall bear,
                    all the out-of-pocket expenses of such actions; provided
                    that Trubion shall reimburse Wyeth for *** of the
                    out-of-pocket expenses incurred in connection therewith. In
                    the event Trubion is the Party paying such expenses, Trubion
                    shall periodically, but no more than once per Calendar
                    Quarter, invoice Wyeth for its *** share of expenses
                    incurred. All invoices shall be accompanied by supporting
                    documentation reasonably showing the expenses so incurred.
                    Such invoices shall be paid within *** of receipt. In the
                    event Wyeth is the Party paying such expenses, Wyeth shall
                    receive a credit in the amount of Trubion's share of such
                    expenses, which credit shall be applied to royalties due to
                    Trubion under Section 5.4, as adjusted under Section 5.4.6;
                    provided that, no such royalty payment to Trubion shall be
                    reduced by more than *** in any Calendar Quarter as a result
                    of such credit. Any portion of the credit not utilized due
                    to the limitations of the preceding sentence shall be
                    carried over and credited to future royalty payments.

               (C)  INTERFERENCE, OPPOSITION, REVOCATION, AND DECLARATORY
                    JUDGMENT ACTIONS. If the Parties, through the Joint Patent
                    Committee, mutually determine that, based upon the review of
                    a Third Party's patent or patent application or other
                    intellectual property rights, it may be desirable to provoke
                    or institute an interference, opposition, revocation or
                    declaratory judgment action with respect thereto, then the
                    Parties shall consult with one another and shall reasonably
                    cooperate in connection with such an action. Unless
                    otherwise determined by the Joint Patent Committee, Wyeth
                    will control such action and shall select counsel for such
                    action. Wyeth shall be responsible for, and shall bear, all
                    the out-of-pocket expenses of such action; provided that
                    Trubion shall reimburse Wyeth for *** of the out-of-pocket
                    expenses incurred in connection therewith. Wyeth shall
                    submit invoices to Trubion for such expenses, such invoices
                    to be accompanied by supporting documentation reasonably
                    showing the expenses so incurred. Trubion shall have the
                    right to participate in and be represented by independent
                    counsel in such action at its own expense.

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<PAGE>

          6.2.4. PATENT CERTIFICATIONS. Each Party shall immediately give
               written notice to the other of any certification of which it
               becomes aware filed pursuant to 21 U.S.C. Section 355(b)(2)(A) or
               Section 355(j)(2)(A)(vii) (or any amendment or successor statute
               thereto), any similar statutory or regulatory requirement enacted
               in the future regarding biologic products, or any similar
               statutory or regulatory requirement in any non-U.S. country in
               the Territory claiming that a Joint Patent Right, Wyeth Patent
               Right or a Trubion Patent Right covering a Licensed Product is
               invalid or that infringement will not arise from the Manufacture,
               use or sale of a product by a Third Party. Upon the giving or
               receipt of such notice, Wyeth shall have the first right, but not
               the obligation, to bring an infringement action against such
               Third Party. In such a case, Wyeth shall notify Trubion at least
               ten (10) days prior to the date set forth by statute or
               regulation of its intent to exercise, or not exercise, this
               right. Any infringement action against a Third Party arising
               under this Section 6.2.4 shall be governed by the provisions of
               Section 6.2.2(b) hereof.

          6.2.5. PATENT TERM RESTORATION. The Parties hereto shall cooperate
               with each other in obtaining patent term restoration, or its
               equivalent anywhere in the Territory, including under 35 U.S.C.
               Section 156 and its foreign counterparts, where applicable to the
               Trubion Patent Rights, Wyeth Patent Rights and Joint Patent
               Rights. If elections with respect to obtaining such patent term
               restoration are to be made, Wyeth shall make such election (after
               consultation with Trubion through the Joint Patent Committee) and
               Trubion shall abide by such election.

     6.3. TRADEMARKS. Wyeth shall, in its sole discretion select and own all
          Licensed Product-related Trademarks, trade dress, logos and copyrights
          and names to be used in connection with the Commercialization of any
          Licensed Product hereunder. Trubion shall neither use nor seek to
          register, anywhere in the Territory, any trademarks which are
          confusingly similar to any Trademark or any other trademarks, trade
          names, trade dress or logos used by or on behalf of Wyeth or its
          sublicensees in connection with any Licensed Product; provided,
          however, that nothing in this Section 6.3 shall be construed to
          prevent Trubion from enforcing its own trademark, trade name, trade
          dress or logo rights or affect the Parties' obligations under Section
          4.13.

7.   CONFIDENTIALITY.

     7.1. CONFIDENTIALITY. Except to the extent expressly authorized by this
          Agreement or otherwise agreed in writing, the Parties agree that, for
          the term of this Agreement and for *** thereafter, each Party (the
          "Receiving Party"), receiving any Confidential Information of the
          other Party (the

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          "Disclosing Party") hereunder shall keep such Confidential Information
          confidential and shall not publish or otherwise disclose or use such
          Confidential Information for any purpose other than as provided for in
          this Agreement except for Confidential Information that the Receiving
          Party can establish:

               (A)  was already known by the Receiving Party (other than under
                    an obligation of confidentiality), at the time of disclosure
                    by the Disclosing Party and such Receiving Party has
                    documentary evidence to that effect;

               (B)  was generally available to the public or otherwise part of
                    the public domain at the time of its disclosure to the
                    Receiving Party;

               (C)  became generally available to the public or otherwise part
                    of the public domain after its disclosure or development, as
                    the case may be, and other than through any act or omission
                    of a Party in breach of this confidentiality obligation;

               (D)  was disclosed to that Party, other than under an obligation
                    of confidentiality, by a Third Party who had no obligation
                    to the Disclosing Party not to disclose such information to
                    others; or

               (E)  was independently discovered or developed by or on behalf of
                    the Receiving Party without the use of the Confidential
                    Information belonging to the other Party and the Receiving
                    Party has documentary evidence to that effect.

     7.2. AUTHORIZED DISCLOSURE AND USE.

          7.2.1. DISCLOSURE. Notwithstanding the foregoing Section 7.1, each
               Party may disclose Confidential Information belonging to the
               other Party to the extent such disclosure is reasonably necessary
               to:

               (A)  file or prosecute patent applications covering Trubion
                    Know-How, Wyeth Know-How or Joint Know-How as contemplated
                    by this Agreement, in a manner consistent with decisions and
                    recommendations of the Joint Patent Committee under Article
                    6, if the affected Party consents to such disclosure (such
                    consent not to be unreasonably withheld or delayed);
                    provided that a disclosure of a Party's Confidential
                    Information under this Section 7.2.1(a) shall be treated as
                    a publication under Section 7.4.3, and shall be subject to
                    the requirements of advance notice, review

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                    period and opportunity to file patent application(s), as set
                    forth in Section 7.4.3,

               (B)  prosecute or defend litigation,

               (C)  exercise rights hereunder provided such disclosure is
                    covered by terms of confidentiality similar to those set
                    forth herein,

               (D)  facilitate discussions with prospective investors (other
                    than pharmaceutical or biotechnology companies) in
                    connection with financing arrangements (not involving any
                    license, collaboration or other arrangement relating to such
                    Party's technology or products) or a proposed acquisition of
                    such Party, subject to appropriate confidentiality
                    agreements and limiting such disclosure to disclosure of the
                    terms and conditions of this Agreement and Know-How to the
                    extent contained in such Party's patent applications; and

               (E)  comply with applicable governmental laws and regulations.

               In the event that a Party shall reasonably deem it necessary to
               disclose, pursuant to this Section 7.2.1, Confidential
               Information belonging to the other Party, the Disclosing Party
               shall to the extent possible give reasonable advance notice of
               such disclosure to the other Party and take reasonable measures
               to ensure confidential treatment of such information.

          7.2.2. USE. Notwithstanding the foregoing Section 7.1, each Party
               shall have the right to use Confidential Information of the other
               Party in carrying out its responsibilities under this Agreement
               in the research, Development, Manufacture and Commercialization
               of Licensed Products.

     7.3. SEC FILINGS. Either Party may disclose the terms of this Agreement to
          the extent required, in the reasonable opinion of such Party's legal
          counsel, to comply with applicable laws, including, without
          limitation, the rules and regulations promulgated by the United States
          Securities and Exchange Commission. Notwithstanding the foregoing,
          before disclosing this Agreement or any of the terms hereof pursuant
          to this Section 7.3, the Parties will reasonably consult with one
          another on the terms of this Agreement to be redacted in making any
          such disclosure. If a Party discloses this Agreement or any of the
          terms hereof in accordance with this Section 7.3, such Party agrees,
          at its own expense, to seek confidential treatment of portions of this
          Agreement or such terms, as may be reasonably requested by the other
          Party.

     7.4. PUBLIC ANNOUNCEMENTS; PUBLICATIONS.

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          7.4.1. COORDINATION. The Parties agree on the importance of
               coordinating their public announcements respecting this Agreement
               and the subject matter thereof (other than academic, scientific
               or medical publications that are subject to the publication
               provision set forth below). Trubion and Wyeth shall, from time to
               time, and at the request of the other Party, discuss and agree on
               the general information content relating to this Agreement
               (including relating to the Research Program and Development
               Program, and/or to research, Development, Manufacture and/or
               Commercialization of Licensed Products) which may be publicly
               disclosed (including, without limitation, by means of any printed
               publication or oral presentation).

          7.4.2. ANNOUNCEMENTS. Except as may be expressly permitted under
               Section 7.3 or Section 7.4.3 or as may be appropriate for Wyeth
               to make in connection with its Commercialization activities as
               contemplated hereunder, subject to Sections 7.1 and 7.2 hereof,
               neither Party will make any public announcement regarding this
               Agreement, the Research Program or the Development Program,
               and/or the research, Development, Manufacturing or
               Commercialization of Licensed Products without the prior written
               approval of the other Party.

          7.4.3. PUBLICATIONS. During the term of this Agreement, each Party
               will submit to the other Party for review and approval all
               proposed academic, scientific and medical publications and public
               presentations relating to the Research Program, the Development
               Program and/or to the research, Development, Manufacture and/or
               Commercialization of any Licensed Product, or any proposed
               disclosure under Section 7.2.1(a), for review in connection with
               preservation of Patent Rights and/or to determine whether any of
               such other Party's Confidential Information should be modified or
               deleted. Written copies of such proposed publications and
               presentations shall be submitted to the non-publishing Party no
               later than thirty (30) days before submission for publication or
               presentation and the non-publishing Party shall provide its
               comments with respect to such publications and presentations
               within fifteen (15) business days of its receipt of such written
               copy. The review period may be extended for an additional thirty
               (30) days in the event the non-publishing Party can demonstrate
               reasonable need for such extension, including, but not limited
               to, the preparation and filing of patent applications. By mutual
               agreement, this period may be further extended. Wyeth and Trubion
               will each comply with standard academic practice regarding
               authorship of scientific publications and recognition of
               contribution of other parties in any publications relating to the
               Research Program, the

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               Development Program and/or to the research, Development,
               Manufacture and/or Commercialization of any Licensed Product.

8.   REPRESENTATIONS AND WARRANTIES.

     8.1. REPRESENTATIONS AND WARRANTIES OF EACH PARTY. Each of Trubion and
          Wyeth hereby represents and warrants to the other Party hereto as
          follows:

               (A)  it is a corporation or entity duly organized and validly
                    existing under the laws of the state or other jurisdiction
                    of its incorporation or formation;

               (B)  the execution, delivery and performance of this Agreement by
                    such Party has been duly authorized by all requisite
                    corporate action and does not require any shareholder action
                    or approval;

               (C)  it has the power and authority to execute and deliver this
                    Agreement and to perform its obligations and to grant the
                    licenses granted by it to the other Party pursuant to this
                    Agreement;

               (D)  the execution, delivery and performance by such Party of
                    this Agreement and its compliance with the terms and
                    provisions hereof does not and will not conflict with or
                    result in a breach of any of the terms and provisions of or
                    constitute a default under (i) any agreement or instrument
                    binding or affecting it or the subject matter of this
                    Agreement; (ii) the provisions of its charter or operative
                    documents or bylaws; or (iii) any order, writ, injunction or
                    decree of any court or governmental authority entered
                    against it or by which any of its property is bound, except
                    where such conflict, breach or default would not materially
                    impact (A) the Party's ability to meet its obligations
                    hereunder or (B) the rights granted to the other Party
                    hereunder; and

               (E)  it has not granted to any Third Party any right or license
                    which would conflict in any material respect with the rights
                    granted by it to the other Party hereunder.

     8.2. ADDITIONAL REPRESENTATIONS AND WARRANTIES OF TRUBION. In addition to
          the representations and warranties made by Trubion in Section 8.1,
          Trubion, subject to Section 8.7, hereby represents and warrants to
          Wyeth that as of the Signing Date:

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               (A)  except as disclosed in Exhibit 8.2(d) attached hereto,
                    Trubion is the sole and exclusive owner of the Trubion
                    Patent Rights and Trubion has not placed, or suffered to be
                    placed, any liens, charges or encumbrances on or against the
                    Trubion Patent Rights;

               (B)  Exhibit 1.129 is a true and complete list of Trubion Patent
                    Rights that pertain to Licensed Products, provided that an
                    inadvertent omission from such list may be cured by amending
                    Exhibit 1.129;

               (C)  the Trubion Patent Rights are existing and, to Trubion's
                    knowledge, no issued or granted patents within the Trubion
                    Patent Rights are invalid or unenforceable;

               (D)  ***;

               (E)  except as set forth in Exhibit 8.2(e) attached hereto, no
                    Trubion Patent Right listed in Exhibit 1.129 attached hereto
                    is subject to any funding agreement with any government or
                    government agency;

               (F)  Trubion has received no written notice alleging infringement
                    of a Third Party Patent Right in connection with its
                    research and Development of SMIPs directed against a Trubion
                    Target, and Trubion has disclosed to Wyeth all material
                    information of which Trubion is aware as to whether the
                    research, Development, Manufacture, use or sale of SMIPs
                    directed against a Trubion Target, in the form that is the
                    subject of the clinical studies ongoing as of the Signing
                    Date, if such SMIPs were researched, Developed,
                    Manufactured, used or sold as of the Signing Date, infringes
                    or would infringe issued or granted patents owned by a Third
                    Party as of the Signing Date;

               (G)  the Trubion Patent Rights are not subject to any litigation,
                    judgments or settlements against or owed by Trubion, nor has
                    Trubion received written notice of any threats of such
                    litigation;

               (H)  Trubion is in compliance in all material respects with all
                    agreements with Third Parties relating to Licensed Products
                    that are sublicensed to Wyeth hereunder;

               (I)  ***

               (J)  the Trubion Patent Rights are not the subject of any
                    interference, opposition, reissue or reexamination

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                    proceeding in the United States or, to the knowledge of
                    Trubion, any opposition proceeding outside of the United
                    States.

     8.3. MUTUAL COVENANT. Each Party covenants to the other Party that it shall
          at all times comply with all applicable material laws and regulations
          relating to its activities under this Agreement.

     8.4. ADDITIONAL COVENANTS OF TRUBION. During the term of this Agreement,
          Trubion will use diligent efforts not to materially breach any
          agreement between Trubion and a Third Party that provides Trubion
          Patent Rights pertaining to the research, Development, Manufacture or
          Commercialization of any Licensed Product, and it will provide Wyeth
          promptly with notice of any such alleged breach. ***. During the term
          of this Agreement, Trubion will not knowingly use any Know-How
          misappropriated from a Third Party in connection with any Licensed
          Product being provided for Commercialization under this Agreement.

     8.5. REPRESENTATION BY LEGAL COUNSEL. Each Party hereto represents that it
          has been represented by legal counsel in connection with this
          Agreement and acknowledges that it has participated in the drafting
          hereof. In interpreting and applying the terms and provisions of this
          Agreement, the Parties agree that no presumption shall exist or be
          implied against the Party which drafted such terms and provisions.

     8.6. NO INCONSISTENT AGREEMENTS. Neither Party has in effect and after the
          Signing Date neither Party shall enter into any oral or written
          agreement or arrangement that would be inconsistent with its
          obligations under this Agreement.

     8.7. DISCLAIMER. EXCEPT AS OTHERWISE EXPRESSLY SET FORTH IN SECTIONS 8.1,
          8.2 AND 8.5, THE PARTIES MAKE NO REPRESENTATIONS AND EXTEND NO
          WARRANTIES OF ANY KIND, EITHER EXPRESS OR IMPLIED, AND PARTICULARLY
          THAT LICENSED PRODUCTS WILL BE SUCCESSFULLY DEVELOPED HEREUNDER, AND
          IF LICENSED PRODUCTS ARE DEVELOPED, WITH RESPECT TO SUCH LICENSED
          PRODUCTS, THE PARTIES DISCLAIM ALL IMPLIED WARRANTIES OF TITLE,
          NON-INFRINGEMENT, MERCHANTABILITY AND FITNESS FOR A PARTICULAR
          PURPOSE.

9.   GOVERNMENT APPROVALS; TERM AND TERMINATION.

     9.1. HSR FILING. Each Party shall be responsible for its own costs,
          expenses, and filing fees associated with any HSR Filing; provided,
          however, that Wyeth shall be solely responsible for any fees (other
          than penalties that may be incurred as a result of actions or
          omissions on the part of Trubion)

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          required to be paid to any government agency in connection with making
          any such HSR Filing.

     9.2. OTHER GOVERNMENT APPROVALS. Trubion and Wyeth will cooperate and use
          respectively all reasonable efforts to make all registrations, filings
          and applications, to give all notices and to obtain as soon as
          practicable all governmental or other consents, transfers, approvals,
          orders, qualifications authorizations, permits and waivers, if any,
          and to do all other things necessary or desirable for the consummation
          of the transactions as contemplated hereby.

     9.3. TERM. The term of this Agreement will commence on the Signing Date and
          shall extend, unless this Agreement is terminated earlier in
          accordance with this Article 9, on a Licensed Product by Licensed
          Product and country by country basis until such time as the Royalty
          Period with respect to the sale of such Licensed Product in such
          country expires.

     9.4. TERMINATION UPON HSR DENIAL. This Agreement shall terminate (a) at
          Wyeth's option, immediately upon written notice to Trubion, in the
          event that the United States Federal Trade Commission and/or the
          United States Department of Justice shall seek a preliminary
          injunction under the HSR Act against Trubion and Wyeth to enjoin the
          transactions contemplated by this Agreement, (b) at the election of
          either Party, immediately upon written notice to the other Party, in
          the event that the United States Federal Trade Commission and/or the
          United States Department of Justice shall obtain a preliminary
          injunction under the HSR Act against Trubion and Wyeth to enjoin the
          transactions contemplated by this Agreement, or (c) at the election of
          either Party, immediately upon written notice to the other Party, in
          the event that the HSR Clearance Date shall not have occurred on or
          prior to *** after the effective date of the HSR Filing.

     9.5. MATERIAL BREACH. In the event that either Party commits a material
          breach of its representations, warranties or obligations under this
          Agreement, the other Party may terminate this Agreement (a) on a
          Licensed Target by Licensed Target and country by country basis, to
          the extent that such material breach relates to Licensed Product(s)
          directed against such Licensed Target(s) in such country(ies) or (b)
          in its entirety only if such material breach fundamentally frustrates
          the objectives or transactions contemplated by this Agreement taken as
          a whole. If a Party elects to exercise such right to terminate, it
          shall do so by providing written notice of the alleged breach (the
          "Notice of Breach") to the breaching Party. If such material breach
          pertains to the payment of undisputed amounts payable under this
          Agreement and remains uncured for *** after the breaching Party's
          receipt of such Notice of Breach or, if such material breach pertains
          to another material breach (other than for non-payment) and remains
          uncured for *** after the breaching Party's receipt of such Notice of
          Breach, then the non-breaching Party may terminate this Agreement, as
          and

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          to the extent permitted in (a) or (b) above, on *** notice by giving a
          written notice of termination ("Notice of Termination") to the
          breaching Party; provided, however, that if such breach (other than
          for non-payment) is not susceptible to cure within the initial ***
          period and the breaching Party uses continuous, diligent, good faith
          efforts to cure such breach, it shall document such efforts by written
          notice to the non-breaching Party on or before the end of such ***
          period, and the stated cure period will be extended by an additional
          ***. This Agreement shall be deemed terminated (as and to the extent
          permitted in (a) or (b) above) *** after the breaching Party's receipt
          of such Notice of Termination, unless the breaching Party has fully
          cured the breach prior to the expiration of such *** period.

          In the event that Trubion is the breaching Party and fails to cure any
          such material breach within the applicable time period(s) set forth
          above, Wyeth, within *** after the expiration of the cure period for
          such breach, may elect, in lieu of terminating this Agreement, by
          written notice to Trubion (a "Notice of Modification"), to modify the
          terms of this Agreement, as (and only to the extent) provided in
          Section 9.8, on a Licensed Target-by-Licensed Target and
          country-by-country basis (but only to the extent such material breach
          relates to Licensed Product(s) directed against such Licensed
          Target(s) in such country(ies)), in which event, Wyeth shall be deemed
          to have waived its right to terminate this Agreement under this
          Section 9.5 with respect to such Licensed Target(s) in such
          country(ies) only with respect to the material breach giving rise to
          such action under this Section 9.5. Notwithstanding the foregoing, a
          Party shall not be in breach of its obligations under this Agreement
          to the extent that such breach was caused by the other Party's failure
          to perform its obligations hereunder.

     9.6. TERMINATION BY WYETH.

          9.6.1. TERMINATION WITHOUT CAUSE. Commencing on the second anniversary
               of the Effective Date, Wyeth shall have the right, exercisable
               upon ninety (90) days prior written notice to Trubion, to
               terminate this Agreement either (a) in its entirety, or (b) on a
               Licensed Target by Licensed Target and country by country basis.
               Wyeth's rights under this Section 9.6.1 are separate from and in
               addition to its rights to terminate the Research Program under
               Section 3.3.2 hereof.

          9.6.2. TERMINATION FOR A MATERIAL SAFETY OR REGULATORY ISSUE. Wyeth
               shall have the right to terminate this Agreement, at any time, on
               a Licensed Target by Licensed Target basis, by giving *** prior
               written notice to Trubion in the event of any safety or
               regulatory issue that would have a material adverse effect on
               Wyeth's ability to research, Develop, Manufacture or
               Commercialize any Licensed Product directed against such

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               Licensed Target, as determined in Wyeth's reasonable judgment and
               according to Wyeth's standard internal procedures for evaluating
               such safety or regulatory issues. Effects of such termination
               shall be as set forth in Section ***.

     9.7. EFFECTS OF TERMINATION.

          9.7.1. EFFECT OF TERMINATION BY WYETH FOR CAUSE.

               (A)  Without limiting any other legal or equitable remedies that
                    Wyeth or Trubion may have, subject to Section 11.3, if this
                    Agreement is terminated in its entirety by Wyeth for cause
                    under Section 9.5, the following provisions shall apply:

                    (I)  all licenses granted by each Party to the other Party
                         under this Agreement shall terminate (except as
                         provided in Section 9.7.10 below);

                    (II) during the *** period after the effective date of such
                         termination, Trubion shall have the right to negotiate
                         with Wyeth an agreement which grants to Trubion a
                         non-exclusive license (with the right to grant
                         sublicenses) to practice, use and exploit the Wyeth
                         Applied Technology with respect to the research,
                         Development, Manufacture and Commercialization of
                         Licensed Products on commercially reasonable terms. If
                         Trubion exercises such right, Wyeth shall negotiate the
                         terms of such license with Trubion diligently and in
                         good faith; provided that, if Trubion and Wyeth
                         negotiate, but do not enter into, such non-exclusive
                         license, Wyeth shall not enter into any agreement
                         granting a license to a Third Party under the Wyeth
                         Applied Technology within *** after the end of such
                         negotiations on terms more favorable to such Third
                         Party than those last offered by Wyeth to Trubion,
                         without first offering Trubion, for a period of not
                         less than ***, the opportunity to review such terms
                         after full disclosure thereof and enter into a
                         non-exclusive license on such more favorable terms,
                         and, if Trubion accepts such more favorable terms, the
                         Parties shall promptly negotiate definitive agreements
                         relating thereto;

                    (III)during the *** period after the effective date of such
                         termination, Trubion shall have the right to negotiate
                         with Wyeth for the transfer of Product Data and Filings
                         to Trubion, and for the grant by Wyeth to

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                         Trubion of the right and license to use the Licensed
                         Product-specific Trademarks and Product-specific names
                         pertaining to the Licensed Product(s) as existing at
                         the time of termination (collectively, "Existing
                         Trademarks"), on commercially reasonable terms. If
                         Trubion exercises such right, Wyeth shall negotiate the
                         terms of such transfer and license with Trubion
                         diligently and in good faith; provided that, if Trubion
                         and Wyeth negotiate but do not enter into such an
                         agreement, Wyeth shall not enter into any agreement
                         granting such rights to a Third Party within *** after
                         the end of such negotiation on terms more favorable to
                         such Third Party than those last offered by Wyeth to
                         Trubion, without first offering Trubion, for a period
                         of not less than ***, the opportunity to review such
                         terms after full disclosure thereof and enter into such
                         an agreement on such more favorable terms, and, if
                         Trubion accepts such more favorable terms, the Parties
                         shall promptly negotiate definitive agreements relating
                         thereto; and

                    (IV) subject to the provisions of Section 9.9, this
                         Agreement shall be of no further force or effect.

               (B)  Without limiting any other legal or equitable remedies that
                    Wyeth or Trubion may have, subject to Section 11.3, if this
                    Agreement is terminated by Wyeth for cause under Section 9.5
                    with respect to a Licensed Target in all countries, but not
                    in its entirety, the following provisions shall apply:

                    (I)  if such Licensed Target is a Trubion Target, all of the
                         Parties' rights and obligations under Article 3 in
                         connection with the Research Program shall cease in
                         their entirety; provided that all amounts due for
                         research performed and costs incurred prior to the date
                         of such termination shall remain payable in accordance
                         with the provisions of Article 3;

                    (II) if such Licensed Target is a Wyeth Target, all of the
                         Parties' rights and obligations under Article 3 in
                         connection with the Research Program shall continue,
                         subject to Wyeth's option, exercisable in its sole
                         discretion, to terminate the Research Program as
                         follows: Wyeth shall exercise such option to terminate
                         the Research Program (if it so elects) by a written
                         statement to that effect included in Wyeth's Notice of
                         Termination (described in Section 9.5 above). If

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                         Wyeth exercises such option to terminate the Research
                         Program, all of the Parties' rights and obligations
                         under Article 3 in connection with the Research Program
                         shall cease in their entirety *** after Trubion's
                         receipt of such Notice of Termination; provided that
                         all amounts due for research performed and costs
                         incurred prior to the date of such termination shall
                         remain payable in accordance with the provisions of
                         Article 3;

                    (III)if such terminated Licensed Target is the CD20 Antigen,
                         Wyeth shall have no further obligation to reimburse
                         Trubion under Section 4.6 with respect to expenses
                         incurred after the effective date of termination;

                    (IV) all licenses granted by each Party to the other Party
                         under this Agreement with respect to Licensed Products
                         directed against such Licensed Target shall terminate
                         (except as provided in Section 9.7.10 below);

                    (V)  the provisions of Section 9.7.1(a)(ii), with such
                         changes as are appropriate in the context of such
                         limited termination, shall apply with respect to the
                         Licensed Products directed against such Licensed
                         Target; and

                    (VI) the provisions of Section 9.7.1(a)(iii), with such
                         changes as are appropriate in the context of such
                         limited termination, shall apply with respect to
                         Product Data and Filings, and Existing Trademarks,
                         relating to the Licensed Products directed against such
                         Licensed Target.

               (C)  Without limiting any other legal or equitable remedies that
                    Wyeth or Trubion may have, subject to Section 11.3, if this
                    Agreement is terminated by Wyeth for cause under Section 9.5
                    with respect to all Licensed Targets in a country, but not
                    in its entirety, the following provisions shall apply:

                    (I)  if such country is a Major Market Country, all of the
                         Parties' rights and obligations under Article 3 in
                         connection with the Research Program shall cease in
                         their entirety; provided that all amounts due for
                         research performed and costs incurred prior to the date

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                         of such termination shall remain payable in accordance
                         with the provisions of Article 3;

                    (II) if such country is not a Major Market Country, all of
                         the Parties' rights and obligations under Article 3 in
                         connection with the Research Program shall continue,
                         subject to Wyeth's option, exercisable in its sole
                         discretion, to terminate the Research Program as
                         follows: Wyeth shall exercise such option to terminate
                         the Research Program (if it so elects) by a written
                         statement to that effect included in Wyeth's Notice of
                         Termination (described in Section 9.5 above). If Wyeth
                         exercises such option to terminate the Research
                         Program, all of the Parties' rights and obligations
                         under Article 3 in connection with the Research Program
                         shall cease in their entirety *** after Trubion's
                         receipt of such Notice of Termination; provided that
                         all amounts due for research performed and costs
                         incurred prior to the date of such termination shall
                         remain payable in accordance with the provisions of
                         Article 3;

                    (III)all licenses granted by each Party to the other Party
                         under this Agreement with respect to such country shall
                         terminate (except as provided in Section 9.7.10 below);
                         and

                    (IV) the term "Territory" as used in this Agreement shall
                         thereafter exclude such country;

                    (V)  except as provided in Section 9.9, neither Wyeth nor
                         Trubion shall have any further obligations under this
                         Agreement with respect to such country;

                    (VI) the provisions of Section 9.7.1(a)(ii), with such
                         changes as are appropriate in the context of such
                         limited termination, shall apply with respect to
                         Licensed Products in such country; and

                    (VII)the provisions of Section 9.7.1(a)(iii), with such
                         changes as are appropriate in the context of such
                         limited termination, shall apply with respect to
                         Product Data and Filings, and Existing Trademarks,
                         relating to Licensed Products in such country.

          9.7.2. EFFECT OF TERMINATION BY TRUBION FOR CAUSE.

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               (A)  Without limiting any other legal or equitable remedies that
                    Trubion or Wyeth may have, subject to Section 11.3, if this
                    Agreement is terminated in its entirety by Trubion for cause
                    under Section 9.5, the following provisions shall apply:

                    (I)  all licenses granted by each Party to the other Party
                         under this Agreement shall terminate (except as
                         provided in Section 9.7.10 below);

                    (II) Wyeth and Trubion shall, upon Trubion's request, such
                         request made within *** after such termination, enter
                         into negotiations of a non-exclusive license from Wyeth
                         to Trubion under which Wyeth will grant to Trubion a
                         non-exclusive license (with the right to grant
                         sublicenses) to practice, use and exploit the Wyeth
                         Applied Technology with respect to the research,
                         Development, Manufacture and Commercialization of
                         Licensed Products as constituted at the time of
                         termination of this Agreement. The Parties hereby agree
                         that such license shall include, inter alia, provisions
                         whereby Trubion shall agree (A) to comply with the
                         applicable requirements of any Third Party license to
                         which the use or exploitation of such Wyeth Applied
                         Technology is subject including, but not limited to the
                         payment of royalties; (B) with respect to any CD20
                         Products ***, to pay to Wyeth (I) if such termination
                         occurs prior ***; (C) with respect to any Licensed
                         Products other than CD20 Products ***; and (D) that
                         Trubion shall have no other financial obligations to
                         Wyeth;

                    (III)the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks) shall apply;

                    (IV) the provisions of Section 9.7.8 (Manufacturing of
                         Licensed Products After Termination) shall apply; and

                    (V)  subject to the provisions of Section 9.9, this
                         Agreement shall be of no further force or effect.

               (B)  Without limiting any other legal or equitable remedies that
                    Trubion or Wyeth may have, subject to Section 11.3, if this
                    Agreement is terminated by Trubion for cause under Section
                    9.5 with respect to a Licensed Target in all

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                    countries, but not in its entirety, the following
                    provisions shall apply:

                    (I)  all of the Parties' rights and obligations under
                         Article 3 in connection with the Research Program shall
                         cease in their entirety; provided that all amounts due
                         for research performed and costs incurred prior to the
                         date of such termination shall remain payable in
                         accordance with the provisions of Article 3;

                    (II) if such terminated Licensed Target is the CD20 Antigen,
                         Wyeth shall have no further obligation to reimburse
                         Trubion under Section 4.6 with respect to expenses
                         incurred after the effective date of termination;

                    (III)all licenses granted by each Party to the other Party
                         under this Agreement with respect to Licensed Products
                         directed against such Licensed Target shall terminate
                         (except as provided in Section 9.7.10 below);

                    (IV) the provisions of Section 9.7.2(a)(ii) (Wyeth's grant
                         of a non-exclusive license to Trubion under Wyeth
                         Applied Technology), with such changes as are
                         appropriate in the context of such limited termination,
                         shall apply to Licensed Products directed against such
                         Licensed Target;

                    (V)  the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks), with such changes as are appropriate in
                         the context of such limited termination, shall apply
                         with respect to Product Data and Filings, and Existing
                         Trademarks, related to Licensed Products directed
                         against such Licensed Target; and

                    (VI) the provisions of Section 9.7.8 (Manufacturing of
                         Licensed Products After Termination), with such changes
                         as are appropriate in the context of such limited
                         termination, shall apply with respect to Licensed
                         Products directed against such Licensed Target.

               (C)  Without limiting any other legal or equitable remedies that
                    Trubion or Wyeth may have, subject to Section 11.3, if this
                    Agreement is terminated by Trubion for cause under

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                    Section 9.5 with respect to all Licensed Targets in a
                    country, but not in its entirety, the following provisions
                    shall apply:

                    (I)  all of the Parties' rights and obligations under
                         Article 3 in connection with the Research Program shall
                         cease in their entirety; provided that all amounts due
                         for research performed and costs incurred prior to the
                         date of such termination shall remain payable in
                         accordance with the provisions of Article 3;

                    (II) all licenses granted by each Party to the other Party
                         under this Agreement with respect to such country shall
                         terminate (except as provided in Section 9.7.10 below);

                    (III)the provisions of Section 9.7.2(a)(ii) (Wyeth's grant
                         of a non-exclusive license to Trubion under Wyeth
                         Applied Technology), with such changes as are
                         appropriate in the context of such limited termination,
                         shall apply to a non-exclusive license to research,
                         Develop, Manufacture and Commercialize Licensed
                         Products in such country;

                    (IV) the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks), with such changes as are appropriate in
                         the context of such limited termination, shall apply
                         with respect to Product Data and Filings, and Existing
                         Trademarks, related to Licensed Products in such
                         country; and

                    (V)  the term "Territory" as used in this Agreement shall
                         thereafter exclude such country.

          9.7.3. EFFECT OF TERMINATION BY WYETH WITHOUT CAUSE.

               (A)  If this Agreement is terminated in its entirety by Wyeth
                    under Section 9.6.1, the following provisions shall apply:

                    (I)  all licenses granted by each Party to the other Party
                         under this Agreement shall terminate (except as
                         provided in Section 9.7.10 below);

                    (II) the provisions of Section 9.7.2(a)(ii) (Wyeth's grant
                         of a non-exclusive license to Trubion under Wyeth
                         Applied Technology) shall apply;

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                    (III)the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks) shall apply;

                    (IV) the provisions of Section 9.7.8 (Manufacturing of
                         Licensed Products After Termination) shall apply; and

                    (V)  subject to the provisions of Section 9.9, this
                         Agreement shall be of no further force or effect.

               (B)  If this Agreement is terminated by Wyeth under Section 9.6.1
                    with respect to a Licensed Target in all countries, but not
                    in its entirety, the following provisions shall apply:

                    (I)  all of the Parties' rights and obligations under
                         Article 3 in connection with the Research Program shall
                         cease in their entirety; provided that all amounts due
                         for research performed and costs incurred prior to the
                         date of such termination shall remain payable in
                         accordance with the provisions of Article 3;

                    (II) if such terminated Licensed Target is the CD20 Antigen,
                         Wyeth shall have no further obligation to reimburse
                         Trubion under Section 4.6 with respect to expenses
                         incurred after the effective date of termination;

                    (III) all licenses granted by each Party to the other Party
                         under this Agreement with respect to Licensed Products
                         directed against such Licensed Target shall terminate
                         (except as provided in Section 9.7.10 below);

                    (IV) the provisions of Section 9.7.2(a)(ii) (Wyeth's grant
                         of a non-exclusive license to Trubion under Wyeth
                         Applied Technology), with such changes as are
                         appropriate in the context of such limited termination,
                         shall apply to a non-exclusive license to research,
                         Develop, Manufacture and Commercialize Licensed
                         Products directed against such Licensed Target;

                    (V)  the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks), with such changes as are appropriate in
                         the context of such limited termination, shall apply
                         with respect to Product Data and Filings, and Existing
                         Trademarks, related to Licensed Products directed
                         against such Licensed Target; and

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                    (VI) the provisions of Section 9.7.8 (Manufacturing of
                         Licensed Products After Termination), with such changes
                         as are appropriate in the context of such limited
                         termination, shall apply with respect to Licensed
                         Products directed against such Licensed Target.

               (C)  If this Agreement is terminated by Wyeth under Section 9.6.1
                    with respect to all Licensed Targets in a country, but not
                    in its entirety, the following provisions shall apply:

                    (I)  if such country is a Major Market Country, all of the
                         Parties' rights and obligations under Article 3 in
                         connection with the Research Program shall cease in
                         their entirety; provided that all amounts due for
                         research performed and costs incurred prior to the date
                         of such termination shall remain payable in accordance
                         with the provisions of Article 3; and if such country
                         is not a Major Market Country, all of the Parties'
                         rights and obligations under Article 3 in connection
                         with the Research Program shall continue;

                    (II) all licenses granted by each Party to the other Party
                         under this Agreement with respect to such country shall
                         terminate (except as provided in Section 9.7.10 below);

                    (III) the provisions of Section 9.7.2(a)(ii) (Wyeth's grant
                         of a non-exclusive license to Trubion under Wyeth
                         Applied Technology), with such changes as are
                         appropriate in the context of such limited termination,
                         shall apply to a non-exclusive license to research,
                         Develop, Manufacture and Commercialize Licensed
                         Products in such country;

                    (IV) the provisions of Section 9.7.7 (Post-Termination
                         Transfer of Product Data and Filings and Existing
                         Trademarks), with such changes as are appropriate in
                         the context of such limited termination, shall apply
                         with respect to Product Data and Filings, and Existing
                         Trademarks, related to Licensed Products in such
                         country; and

                    (V)  the term "Territory" as used in this Agreement shall
                         thereafter exclude such country.

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          9.7.4. EFFECT OF TERMINATION BY WYETH FOR A MATERIAL SAFETY OR
               REGULATORY ISSUE. If this Agreement is terminated with respect to
               a Licensed Target by Wyeth under Section 9.6.2, the following
               provisions shall apply:

               (A)  all of the Parties' rights and obligations under Article 3
                    in connection with the Research Program shall continue;

               (B)  if such terminated Licensed Target is the CD20 Antigen,
                    Wyeth shall have no further obligation to reimburse Trubion
                    under Section 4.6 with respect to with respect to expenses
                    incurred after the effective date of termination;

               (C)  all licenses granted by each Party to the other Party under
                    this Agreement with respect to Licensed Products directed
                    against such Licensed Target shall terminate (except as
                    provided in Section 9.7.10 below);

               (D)  unless the basis of termination under Section 9.6.2 is the
                    IMPOSITION OF a clinical hold by a Regulatory Authority, a
                    determination by Wyeth to place a hold on further clinical
                    studies of a Licensed Product directed against such Licensed
                    Target (such determination to be made by Wyeth in accordance
                    with its standard procedures of addressing such safety
                    issues) or a withdrawal of a Licensed Product from the
                    market for patient safety reasons, whether voluntary or
                    otherwise, the provisions of Section 9.7.2(a)(ii) (Wyeth's
                    grant of a non-exclusive license to Trubion under Wyeth
                    Applied Technology), with such changes as are appropriate in
                    the context of such limited termination, shall apply to a
                    non-exclusive license to research, Develop, Manufacture and
                    Commercialize Licensed Products directed against such
                    Licensed Target;

               (E)  the provisions of Section 9.7.7 (Post-Termination Transfer
                    of Product Data and Filings and Existing Trademarks), with
                    such changes as are appropriate in the context of such
                    limited termination, shall apply with respect to Product
                    Data and Filings, and Existing Trademarks, related to
                    Licensed Products directed against such Licensed Target; and

               (F)  unless the basis of termination under Section 9.6.2 is the
                    imposition of a clinical hold by a Regulatory Authority, a
                    determination by Wyeth to place a hold on further clinical
                    studies of a Licensed Product directed against such Licensed
                    Target (such determination to be made by Wyeth

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                    in accordance with its standard procedures of addressing
                    such safety issues) or a withdrawal of a Licensed Product
                    from the market for patient safety reasons, whether
                    voluntary or otherwise, the provisions of Section 9.7.8
                    (Manufacturing of Licensed Products After Termination), with
                    such changes as are appropriate in the context of such
                    limited termination, shall apply with respect to Licensed
                    Products directed against such Licensed Target.

          9.7.5. POST-TERMINATION RIGHTS TO WYETH TECHNOLOGY AND TRUBION
               TECHNOLOGY. Except as otherwise expressly set forth in this
               Agreement, expiration or termination of this Agreement for any
               reason shall have no effect on Wyeth's rights with respect to the
               Wyeth Technology, and Trubion shall have no right, title or
               interest in or to any of the Wyeth Technology, and such
               expiration or termination shall have no effect on Trubion's
               rights with respect to the Trubion Technology, and Wyeth shall
               have no right, title or interest in or to any of the Trubion
               Technology.

          9.7.6. POST-TERMINATION LICENSES TO WYETH TECHNOLOGY. ***

          9.7.7. POST-TERMINATION TRANSFER OF PRODUCT DATA AND FILINGS AND
               EXISTING TRADEMARKS. The following provisions shall apply in the
               event of termination by Trubion under Section 9.5 or termination
               by Wyeth under Section 9.6. To the extent permitted by applicable
               law, Wyeth shall assign and transfer to Trubion Wyeth's entire
               right, title and interest in and to Product Data and Filings,
               provide copies of all the Research Program Data, and license or
               otherwise transfer rights to Existing Trademarks that are
               necessary or useful for Trubion to continue to research, Develop,
               Manufacture or Commercialize Licensed Products as constituted at
               the time of termination. To the extent such Research Program
               Data, Product Data and Filings and other rights or items were
               previously transferred from Trubion to Wyeth, Wyeth shall perform
               such transfer at no cost to Trubion. To the extent such Research
               Program Data and Product Data and Filings were not previously
               transferred from Trubion to Wyeth, Trubion shall reimburse Wyeth
               for its reasonable out-of-pocket expenses in connection with such
               transfer, and such transfer shall be pursuant to an instrument in
               form and substance reasonably satisfactory to Trubion. Wyeth
               shall perform all other actions reasonably requested by Trubion
               to effect and confirm such transfer. After receipt of Trubion's
               request consistent with the foregoing, Wyeth shall provide to
               Trubion, within *** of receipt of such request, complete copies
               of such Product Data and Filings, including, without limitation,

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               relevant clinical data, INDs, additional regulatory filings with
               FDA or other Regulatory Authorities, supplements or amendments
               thereto, all written correspondence with FDA or other Regulatory
               Authorities regarding the regulatory filings, and all existing
               written minutes of meetings and memoranda of conversations
               between Wyeth (including, to the extent practicable, Wyeth's
               investigators) and FDA or other Regulatory Authorities in Wyeth's
               possession (or in the possession of any of Wyeth's agents and
               subcontractors, such as contract research organizations used by
               Wyeth), to the extent Wyeth has the right to access and provide
               to Trubion such Product Data and Filings, regarding such
               regulatory filings, each to the extent they relate to Licensed
               Products. Within thirty (30) days (or such later date as Trubion
               may request) after the date of receipt of Trubion's request,
               Wyeth shall execute and deliver a letter to the FDA or other
               Regulatory Authorities, in a form approved by Trubion,
               transferring ownership to Trubion of such regulatory filings, if
               any, filed in the name of Wyeth that are related to Licensed
               Products.

          9.7.8. MANUFACTURING OF LICENSED PRODUCTS AFTER TERMINATION. If (a)
               with respect to a particular Licensed Target, Trubion terminates
               this Agreement pursuant to Section 9.5 hereof or Wyeth terminates
               this Agreement pursuant to Section 9.6 hereof, and (b) Wyeth is
               engaged in the Manufacturing of a Licensed Product directed
               against such Licensed Target on the date the terminating Party
               gives notice of termination under Section 9.5 or Section 9.6, as
               the case may be, then Wyeth shall Manufacture such Licensed
               Product for Trubion and use Commercially Reasonable Efforts to
               supply Trubion with its entire requirements of such Licensed
               Product until (i) the *** anniversary of the effective date of
               such termination if at the time of such notice there shall have
               been filed a Regulatory Approval Application for such Licensed
               Product or (ii) the *** anniversary of the effective date of such
               termination if at the time of such notice there shall not have
               been filed a Regulatory Approval Application for such Licensed
               Product; provided, however, that (w) Wyeth shall not be required
               to conduct any activities to increase the scale on which it is
               then Manufacturing such Licensed Product, (x) Wyeth shall not be
               required to Manufacture or supply such Licensed Product in an
               amount in excess of its available capacity in the Manufacturing
               suite that was used by Wyeth for the Manufacture of such Licensed
               Product (taking into account the other uses Wyeth is making of
               the manufacturing suite as of the date of the Notice of
               Termination) or to change the location of the Manufacturing
               activities, (y) Wyeth shall have no obligation to maintain idle

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               capacity in such manufacturing suite for purposes of meeting such
               Manufacturing obligations and (z) Wyeth may at its option assign
               to Trubion one or more of its Licensed Product manufacturing
               agreements with Third Parties, to the extent assignable, in lieu
               of continuing to contract directly with such Third Parties. The
               purchase price for such Licensed Product units actually
               Manufactured by Wyeth shall be at Wyeth's fully absorbed
               manufacturing cost plus ***, and Wyeth's obligations under this
               Section 9.7.8 shall be subject to the execution of a supply
               agreement and a quality agreement, each mutually acceptable to
               both Parties, which agreements shall contain the terms set forth
               in this Section 9.7.8 and such other reasonable terms as mutually
               agreed by the Parties.

          9.7.9. POST-TERMINATION DISPOSITION OF INVENTORIES OF LICENSED
               PRODUCTS. Following termination of this Agreement with respect to
               one or more Licensed Targets, Wyeth and its sublicensees shall
               have the right to continue to sell their existing inventories of
               Licensed Products directed against such Licensed Targets for a
               period not to exceed *** after the effective date of such
               termination. Wyeth shall pay royalties and report on such sales,
               and maintain records thereon, in accordance with Sections 5.4,
               5.5 and 5.6, which shall survive termination for such purpose.

          9.7.10. CONTINUATION OF RIGHTS AND LICENSES UNDER SECTIONS 6.1.1 AND
               6.1.2. Notwithstanding anything in this Section 9.7 to the
               contrary, the Parties' rights and licenses set forth in Sections
               6.1.1 and 6.1.2 shall survive any expiration or termination of
               this Agreement.

          9.7.11. CONTINUATION OF OTHER RIGHTS AND OBLIGATIONS. Except as
               expressly provided to the contrary in this Section 9.7, in the
               event that a Party exercises any right that results in the
               termination of some, but not all, of the Parties' rights and
               obligations under this Agreement, all non-terminated rights and
               obligations of the Parties shall continue in full force and
               effect.

     9.8. MODIFICATION OF AGREEMENT TERMS BY WYETH. Without limiting any other
          legal or equitable remedies that Wyeth or Trubion may have, subject to
          Section 11.3, in the event that Wyeth elects to modify the terms of
          this Agreement as provided in Section 9.5, in lieu of terminating this
          Agreement under Section 9.5, with respect to one or more Licensed
          Targets identified by Wyeth in its Notice of Modification (the
          "Designated Target(s)"), the following terms shall apply:

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          9.8.1. except as set forth in Section 9.8.4 below, all rights and
               obligations of the Parties under this Agreement shall continue in
               full force and effect, and shall not be subject to any unilateral
               modification by Wyeth; provided that, ***;

          9.8.2. all licenses granted by Trubion to Wyeth under this Agreement
               with respect to Licensed Products directed against each
               Designated Target shall remain in effect;

          9.8.3. all of the Parties' rights and obligations under Article 3 in
               connection with the Research Program shall cease in their
               entirety; provided that all amounts due for research performed
               and costs incurred prior to the date of such termination shall
               remain payable in accordance with the provisions of Article 3;
               and

          9.8.4  ***

     9.9. SURVIVAL OF CERTAIN OBLIGATIONS. Expiration or termination of this
          Agreement shall not relieve the Parties of any obligation accrued or
          accruing before such expiration or termination (including situations
          where it becomes clear only after the time of such expiration or
          termination that such obligation had already accrued). The following
          provisions shall survive the expiration or termination of this
          Agreement: Article 1 (to the extent definitions are embodied in the
          following listed Articles and Sections); Sections 3.6.3, 3.7, 5.6,
          6.1.1, 6.1.2, 9.2, 9.5, 9.6, 9.7, 9.9, 9.10.2, 12.3, 12.6, 12.8, 12.9,
          12.10, 12.11 and 12.12; and Articles 7, 10 and 11. Any expiration or
          early termination of this Agreement shall be without prejudice to the
          rights of either Party against the other accrued or accruing under
          this Agreement before expiration or termination, including, without
          limitation, the obligations (1) to provide research funding and
          reimbursement of expenses for activities undertaken prior to such
          expiration or termination under and in accordance with Sections 3.6.1,
          3.6.2, 4.6, 4.9, 6.1.3, 6.2.1(a), (c) and (d), 6.2.2(b) and (c), and
          6.2.3(b) and (c); and (2) to pay royalties for Licensed Products sold
          before such expiration or termination, and, to the extent permitted
          under Section 9.7.9, after expiration or termination in accordance
          with Section 5.4 (and subject to the related obligations under Section
          5.5); and (3) to pay any Additional Research and Development Expense
          Payments in connection with any events specified on Exhibit 5.3 that
          are achieved prior to such expiration or termination, but with respect
          to which the corresponding payments under Exhibit 5.3 were not paid
          prior to such expiration or termination.

     9.10. CHANGE OF CONTROL.

          9.10.1. DEFINITION. With respect to any Party, a "Change of Control"
               means an event in which: (a) any other person or group of

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               persons (as the term "person" is used for purposes of Section
               13(d) or 14(d) of the Exchange Act) not then beneficially owning
               more than fifty percent (50%) of the voting power of the
               outstanding securities of such Party acquires or otherwise
               becomes the beneficial owner (within the meaning of Rule 13d-3
               promulgated under the Exchange Act) of securities of such Party
               representing more than fifty percent (50%) of the voting power of
               the then outstanding securities of such Party with respect to the
               election of directors of such Party; or (b) such Person (i)
               consummates a merger, consolidation or similar transaction with
               another Person where the voting securities of such Party
               outstanding immediately preceding such transaction (or the voting
               securities issued with respect to the voting securities of such
               Party outstanding immediately preceding such transaction)
               represent less than fifty percent (50%) of the voting power of
               such Party or surviving entity, as the case may be, immediately
               following such transaction, (ii) sells or otherwise transfers to
               any Person(s) in one or more related transactions more than fifty
               percent (50%) of its consolidated total assets, or assets from
               which more than fifty percent (50%) of its consolidated operating
               income for its most recent financial year was derived, (iii)
               disposes by sale, assignment, exclusive license or otherwise of
               all or substantially all of its intellectual property rights,
               except for licenses under such intellectual property rights in
               the ordinary course of business and any isolated sale or
               assignment of specific items of intellectual property, or (iv)
               liquidates, dissolves or winds-up; or (c) with respect to Wyeth
               and with respect to Trubion, (at any time following any public
               offering of voting securities by Trubion), any "person" (as the
               term "person" is used for the purposes of Sections 13(d) or 14(d)
               of the Exchange Act) other than Wyeth acquires nineteen and
               nine-tenths percent (19.9%) or more of the voting power of the
               then-outstanding voting securities of such Party.

          9.10.2. CHANGE OF CONTROL OF WYETH.

               (A)  In the event that any transaction results in a Change of
                    Control of Wyeth, Trubion shall be entitled to request
                    further written assurances from the successor in interest to
                    Wyeth (the "Successor Party") re-affirming the commitment of
                    the Successor Party to comply with the terms and conditions
                    of the Agreement. Such further written assurances shall be
                    delivered within *** of written request by Trubion. Trubion
                    may so request at any time during the *** period following
                    completion of the subject transaction. Subject to the
                    operation of Section 9.10.2(b) below, the failure of such
                    Successor Party to provide the

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                    requested written assurance shall be deemed to be a material
                    breach of the Agreement.

               (B)  In the event that in connection with, or during the ***
                    period following, a Change of Control of Wyeth, Wyeth or the
                    Successor Party is required, or voluntarily decides, to
                    divest itself of one or more Licensed Products, Wyeth or the
                    Successor Party, subject to any restrictions or limitations
                    imposed by the Federal Trade Commission or other
                    governmental agency on such divestiture, shall offer to
                    Trubion an exclusive opportunity to negotiate the
                    acquisition or license of all rights of Wyeth or such
                    Successor Party, as the case may be, to such Licensed
                    Product(s) on commercially reasonable terms. In the event
                    that Trubion and the Successor Party, after *** good faith
                    negotiations, are unable to conclude a definitive agreement
                    regarding the acquisition or license of such Licensed
                    Product(s), the Successor Party shall be entitled to divest
                    itself of such Licensed Product(s) to a party other than
                    Trubion; provided, however, no such divestiture to a Third
                    Party shall take place on terms more favorable to such Third
                    Party than those last offered by the Successor Party to
                    Trubion, without first offering such Licensed Product(s) to
                    Trubion on such more favorable terms. Such Third Party shall
                    be required to assume all of the Successor Party's
                    obligations owed to Trubion pursuant to this Agreement with
                    respect to the Licensed Product(s) so divested.

               (C)  In the event of a Change of Control of Wyeth, the
                    restrictive covenants set forth in Sections 2.3.1 and 2.3.2
                    (the "Exclusivity Covenants") shall apply to the Successor
                    Party's then-existing Development and Commercialization
                    activities that otherwise would violate the Exclusivity
                    Covenants (the "Existing Activities"). In such event,
                    Trubion shall have the right, exercisable upon written
                    notice given by Trubion (an "Exercise Notice") within ***
                    after consummation of the Change of Control, to require such
                    Successor Party to engage in good faith discussions
                    regarding the terms and conditions on which such Successor
                    Party would pay reasonable financial consideration to
                    Trubion with respect to such Existing Activities. If Trubion
                    and such Successor Party do not agree on such terms and
                    conditions within *** after Trubion gives the Exercise
                    Notice (or such longer period as may be agreed to by such
                    parties), or if such Successor Party notifies Trubion in
                    writing during such *** period that it does not desire to
                    engage in such discussions,

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                    Trubion shall have the right, exercisable upon written
                    notice given by Trubion within ten (10) days (i) after the
                    end of such *** period (or such longer period as agreed to
                    by such parties) or (ii) after receipt of such notice from
                    such Successor Party, to require such Successor Party to
                    enter into an agreement to divest to a Third Party either
                    (a) the Existing Activities or (b) the relevant CD20
                    Products or ***, as the case may be (such Third Party, in
                    the case of a divestiture of the relevant CD20 Products or
                    ***, to be reasonably acceptable to Trubion) within ***
                    after the date of such notice by Trubion, subject to
                    applicable governmental and regulatory approval. If such
                    Successor Party does not enter into an agreement with a
                    Third Party (such Third Party, in the case of a divestiture
                    of the relevant CD20 Products or ***, to be reasonably
                    acceptable to Trubion) to divest such Existing Activities or
                    such Products within such *** period (or if such Successor
                    Party does enter into such an agreement but such agreement
                    terminates after such *** period and such divestiture is not
                    consummated) or if such Successor Party notifies Trubion in
                    writing that it does not intend to divest such Existing
                    Activities or such Products, Trubion shall have the right,
                    exercisable within *** after the end of such *** period (or
                    upon termination of such agreement, if later) to terminate,
                    in its sole discretion, all CD20-related licenses (only
                    where such Existing Activities relate to products directed
                    against the CD20 Antigen which would otherwise violate
                    Wyeth's exclusivity covenants in Section 2.3.1 hereof)
                    and/or all *** (only where such Existing Activities relate
                    to products directed against the *** which would otherwise
                    violate Wyeth's exclusivity covenants in Section 2.3.2
                    hereof) granted to Wyeth under the Agreement, on those terms
                    and subject to those conditions that would apply to a
                    termination by Wyeth without cause.

          9.10.3. CHANGE OF CONTROL OF TRUBION. In the event of a Change of
               Control of Trubion where the acquiring party is a top fifteen
               (15) pharmaceutical company (measured by market capitalization),
               Wyeth shall have the right to ***

10.  INDEMNIFICATION AND INSURANCE.

     10.1. INDEMNIFICATION BY WYETH. Wyeth will indemnify, defend and hold
          harmless Trubion, and each of its respective employees, officers,
          directors and agents (each, a "Trubion Indemnified Party") from and
          against any and all liability, loss, damage, expense (including
          reasonable attorneys' fees and expenses) and cost (collectively,
          "Liabilities") that the Trubion Indemnified

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          Party may be required to pay to one or more Third Parties resulting
          from or arising out of:

               (A)  any claims of any nature pertaining to any act or omission
                    related to performance under this Agreement by, on behalf
                    of, or under the authority of Wyeth (other than by any
                    Trubion Indemnified Party) including, but not limited to,
                    research, Development, Manufacture or Commercialization of
                    Licensed Product(s) or any violation of applicable law, rule
                    or regulation by, on behalf of, or under the authority of
                    Wyeth (other than by any Trubion Indemnified Party); and/or

               (B)  any Wyeth representation or warranty set forth herein being
                    untrue in any material respect when made;

          except in each case, to the extent caused by the negligence or willful
          misconduct of Trubion or any other Trubion Indemnified Party.

     10.2. INDEMNIFICATION BY TRUBION. Trubion will indemnify, defend and hold
          harmless Wyeth and its sublicensees, distributors and each of its and
          their respective employees, officers, directors and agents (each, a
          "Wyeth Indemnified Party") from and against any and all Liabilities
          that the Wyeth Indemnified Party may be required to pay to one or more
          Third Parties resulting from or arising out of:

               (A)  any claims of any nature pertaining to any act or omission
                    related to performance under this Agreement by, on behalf
                    of, or under the authority of Trubion (other than by any
                    Wyeth Indemnified Party) or any violation of applicable law,
                    rule or regulation by, on behalf of, or under the authority
                    of Trubion (other than by any Wyeth Indemnified Party);
                    and/or

               (B)  any Trubion representation or warranty set forth herein
                    being untrue in any material respect when made;

          except in each case, to the extent caused by the negligence or willful
          misconduct of Wyeth or any other Wyeth Indemnified Party.

     10.3. PROCEDURE. Each Party will notify the other in the event it becomes
          aware of a claim for which indemnification may be sought hereunder. In
          case any proceeding (including any governmental investigation) shall
          be instituted involving any Party in respect of which indemnity may be
          sought pursuant to this Article 10, such Party (the "Indemnified
          Party") shall promptly notify the other Party (the "Indemnifying
          Party") in writing within fifteen (15) days and the Indemnifying Party
          and Indemnified Party shall meet to

                                                                              90

<PAGE>

          discuss how to respond to any claims that are the subject matter of
          such proceeding. The Indemnifying Party, upon request of the
          Indemnified Party, shall retain counsel reasonably satisfactory to the
          Indemnified Party to represent the Indemnified Party and shall pay the
          fees and expenses of such counsel related to such proceeding. The
          Indemnified Party agrees to cooperate fully with the Indemnifying
          Party in the defense of any such claim, action or proceeding, or any
          litigation resulting from any such claim. In any such proceeding, the
          Indemnified Party shall have the right to retain its own counsel, but
          the fees and expenses of such counsel shall be at the expense of the
          Indemnified Party unless (a) the Indemnifying Party and the
          Indemnified Party shall have mutually agreed to the retention of such
          counsel or (b) the named parties to any such proceeding (including any
          impleaded parties) include both the Indemnifying Party and the
          Indemnified Party and representation of both Parties by the same
          counsel would be inappropriate due to actual or potential differing
          interests between them. All such fees and expenses shall be reimbursed
          as they are incurred. The Indemnifying Party shall not be liable for
          any settlement of any proceeding effected without its written consent,
          but if settled with such consent or if there be a final judgment for
          the plaintiff, the Indemnifying Party agrees to indemnify the
          Indemnified Party from and against any loss or liability by reason of
          such settlement or judgment. The Indemnifying Party shall not, without
          the written consent of the Indemnified Party, effect any settlement of
          any pending or threatened proceeding in respect of which the
          Indemnified Party is, or arising out of the same set of facts could
          have been, a party and indemnity could have been sought hereunder by
          the Indemnified Party, unless such settlement includes an
          unconditional release of the Indemnified Party from all liability on
          claims that are the subject matter of such proceeding.

     10.4. INSURANCE. Each Party shall use Commercially Reasonable Efforts to
          obtain and maintain, during the term of this Agreement, commercial
          general liability insurance, including products liability insurance,
          with reputable and financially secure insurance carriers to cover its
          indemnification obligations under Sections 10.1 or 10.2, as
          applicable, or self-insurance, in each case with limits of not less
          than *** per occurrence and in the aggregate. Insurance shall be
          procured with carriers having an A.M. Best Rating of A-VII or better.

11.  DISPUTE RESOLUTION.

     11.1. GENERAL. Any controversy, claim or dispute arising out of or relating
          to this Agreement shall be settled, if possible, through good faith
          negotiations between the Parties. If, however, the Parties are unable
          to settle such dispute after good faith negotiations, the matter shall
          be referred to the Executive Officers to be resolved by negotiation in
          good faith as soon as is practicable but in no event later than thirty
          (30) days after referral. Such

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<PAGE>

          resolution, if any, of a referred issue shall be final and binding on
          the Parties.

     11.2. FAILURE OF EXECUTIVE OFFICERS TO RESOLVE DISPUTE. If the Executive
          Officers are unable to settle the dispute after good faith negotiation
          in the manner set forth above, either Party (including its successors
          and permitted assigns but excluding its Affiliates unless an Affiliate
          is a successor or permitted assign) may seek resolution of the dispute
          through any remedies available at law or in equity from any court of
          competent jurisdiction.

     11.3. DISCLAIMER OF CONSEQUENTIAL AND PUNITIVE DAMAGES. Subject to and
          without limiting the indemnification obligations of each Party under
          Article 10, under no circumstances shall either Party be liable to the
          other Party for consequential or punitive damages arising out of or
          relating to this Agreement or any breach thereof. Both Parties hereby
          disclaim such damages.

12.  MISCELLANEOUS.

     12.1. PERIODIC EXECUTIVE MEETINGS. The Chief Executive Officer of Trubion,
          the Senior Vice President, Research and Development of Trubion, the
          Executive Vice President and General Manager of the Wyeth
          Pharmaceuticals Biopharma Business Unit and the Executive Vice
          President and Operating Officer of Wyeth's Research Division (and such
          other executive officers of the Parties as may be designated from time
          to time by the Parties) shall meet from time to time during the first
          *** of the term of this Agreement to review and discuss the Parties'
          activities under this Agreement. Such meetings will be held on a
          quarterly basis or such other periodic basis as such executive
          officers decide, and will take place in locations selected by such
          executive officers. Such meetings may take place by telephone or video
          conference.

     12.2. ASSIGNMENT. Neither this Agreement nor any interest hereunder shall
          be assignable by either Party, without the prior written consent of
          the other Party, which consent shall not be unreasonably withheld or
          delayed, except a Party may make such an assignment without the other
          Party's consent to Affiliates or to a successor to substantially all
          of the business of such Party to which this Agreement relates, whether
          in merger, sale of stock, sale of assets or other transaction. This
          Agreement shall be binding upon the successors and permitted assigns
          of the Parties, 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. In addition to the foregoing, Trubion may assign its right,
          in whole or part, to receive payments under this Agreement; provided,
          however, Trubion shall notify Wyeth of its intention to do so and
          shall provide Wyeth an opportunity for at least *** to negotiate in
          good

                                                                              92

<PAGE>

          faith the purchase of any such right Trubion intends to so assign. Any
          assignment not in accordance with this Section 12.2 shall be void.

     12.3. 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 the Agreement.

     12.4. FORCE MAJEURE. Neither Party shall be liable to the other for delay
          or failure in the performance of the obligations on its part contained
          in this Agreement if and to the extent that such failure or delay is
          due to circumstances beyond its control which it could not have
          avoided by the exercise of reasonable diligence. It shall notify the
          other Party promptly should such circumstances arise, giving an
          indication of the likely extent and duration thereof, and shall use
          all Commercially Reasonable Efforts to resume performance of its
          obligations as soon as practicable; provided, however, that neither
          Party shall be required to settle any labor dispute or disturbance.

     12.5. NON-SOLICITATION. During the period between the Effective Date and
          the later of (a) the end of *** or (b) the date ***, but in the case
          of (a) and (b) not later than the *** of the Effective Date, neither
          Trubion nor the Wyeth pharmaceuticals business operating in the United
          States ("U.S. Wyeth Pharmaceuticals") shall solicit for employment any
          key or technical employee(s) of the other Party who become known to
          U.S. Wyeth Pharmaceuticals or Trubion, as the case may be, through the
          transactions contemplated by this Agreement without the other's prior
          written consent (which consent may be granted or denied in the other's
          sole discretion); provided, however, that nothing in this Section 12.5
          shall prohibit U.S. Wyeth Pharmaceuticals or Trubion, as the case may
          be, from hiring any employees of the other who respond to general
          employment solicitations not targeted at the employees of the other,
          advertised employment opportunities, or hiring by the other by
          personnel not working on the transactions contemplated by this
          Agreement or who are not otherwise directly or indirectly exposed to
          the personnel working thereon.

     12.6. CORRESPONDENCE AND NOTICES.

          12.6.1. ORDINARY NOTICES. Correspondence, reports, documentation, and
               any other communication in writing between the Parties in the
               course of ordinary implementation of this Agreement shall be
               delivered by hand, sent by facsimile transmission (receipt
               verified), or by airmail to the employee or representative of the
               other Party who is designated by such other Party to receive such
               written communication.

                                                                              93

<PAGE>

          12.6.2. EXTRAORDINARY NOTICES. Extraordinary notices and other
               communications hereunder (including, without limitation, any
               notice of force majeure, breach, termination, change of address,
               etc.) 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 nationally recognized
               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):

          All correspondence to Wyeth shall be addressed as follows:

               Wyeth Pharmaceuticals
               500 Arcola Road
               Collegeville, Pennsylvania 19426
               Attn: Senior Vice President, Corporate Business Development
               Fax: (484) 865-6476

          with a copy to:

               Wyeth
               5 Giralda Farms
               Madison, New Jersey 07940
               Attn: Executive Vice President and General Counsel
               Fax: (973) 660-7156

          All correspondence to Trubion shall be addressed as follows:

               Trubion Pharmaceuticals, Inc.
               2401 4th Avenue
               Suite 1050
               Seattle, Washington 98121
               Attn: President & CEO
               Fax: (206) 838-0503

          with a copy to:

               Trubion Pharmaceuticals, Inc.
               Vice President, Legal Affairs
               2401 4th Avenue
               Suite 1050
               Seattle, Washington 98121
               Fax: (206) 838-0503

                                                                              94

<PAGE>

     12.7. 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.

     12.8. WAIVER. No provision of the Agreement shall be waived by any act,
          omission or knowledge of a 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. The waiver by
          either of the Parties of any breach of any provision hereof by the
          other Party shall not be construed to be a waiver of any succeeding
          breach of such provision or a waiver of the provision itself.

     12.9. SEVERABILITY. If any clause or portion thereof in this Agreement is
          for any reason held to be invalid, illegal or unenforceable, the same
          shall not affect any other portion of this Agreement, as it is the
          intent of the Parties that this Agreement shall be construed in such
          fashion as to maintain its existence, validity and enforceability to
          the greatest extent possible. In any such event, this Agreement shall
          be construed as if such clause of portion thereof had never been
          contained in this Agreement, and there shall be deemed substituted
          therefor such provision as will most nearly carry out the intent of
          the Parties as expressed in this Agreement to the fullest extent
          permitted by applicable law.

     12.10. DESCRIPTIVE HEADINGS. The descriptive headings of this Agreement are
          for convenience only, and shall be of no force or effect in construing
          or interpreting any of the provisions of this Agreement.

     12.11. GOVERNING LAW. This Agreement shall be governed by and interpreted
          in accordance with the substantive laws of the State of New York,
          without regard to conflict of law principles thereof.

     12.12. ENTIRE AGREEMENT OF THE PARTIES. This Agreement constitutes and
          contains the complete, final and exclusive understanding and agreement
          of the Parties and cancels and supersedes any and all prior
          negotiations, correspondence, understandings and agreements, whether
          oral or written, among the Parties respecting the subject matter
          hereof and thereof, including, but not limited to, that certain
          Non-Disclosure Agreement of the Parties effective May 27, 2004. For
          the avoidance of doubt, disclosures made under such Confidentiality
          Agreement shall continue to be subject to the terms of this Agreement
          as if first disclosed pursuant hereto. Except as expressly set forth
          in this Agreement, neither Party shall have any other obligations,
          whether by implication or otherwise, with respect to the research,
          Development, Manufacture or Commercialization of Licensed Products.

                                                                              95

<PAGE>

     12.13. INDEPENDENT CONTRACTORS. Both Parties are independent contractors
          under this Agreement. Nothing herein contained shall be deemed to
          create an employment, agency, joint venture or partnership
          relationship between the Parties hereto or any of their agents or
          employees, or any other legal arrangement that would impose liability
          upon one Party for the act or failure to act of the other Party.
          Neither Party shall have any express or implied power to enter into
          any contracts or commitments or to incur any liabilities in the name
          of, or on behalf of, the other Party, or to bind the other Party in
          any respect whatsoever.

     12.14. 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. Facsimile signatures shall be
          binding upon the Parties and shall be treated as if originals.

     IN WITNESS WHEREOF, duly authorized representatives of the Parties have
duly executed this Agreement to be effective as of the Signing Date.

WYETH,                                  TRUBION PHARMACEUTICALS, INC.
ACTING THROUGH ITS
WYETH PHARMACEUTICALS DIVISION

By /s/ William M. Haskel                By /s/ Peter A. Thompson
   ----------------------------------      -------------------------------------
Name: William M. Haskel                 Name: Peter A. Thompson, M.D.
Title: Vice President                   Title: President & CEO

                                                                              96

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 1.122
                                     TRU-015

***

As of the Signing Date, TRU-015 is investigated in the Phase IIa Clinical Study.

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 1.129
                              TRUBION PATENT RIGHTS

***

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 1.132
                         TRUBION THIRD PARTY AGREEMENTS

***

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 3.2.1
                            TRUBION'S "MILESTONE ONE"

MILESTONE #1

Defined in Trubion's internal project management process, which may be modified
from time to time.

The following specifications are determined:

     -    Scientific Rationale that supports the therapeutic potential

          -    Mechanism of Action (MOA)

     -    Specific biochemical and therapeutic properties (targeted)

          -    Binding Domain

          -    Target

          -    In vivo activity

          -    Safety

          -    pk

     -    Market rationale (preliminary) for product profile

          -    Economics (COGs)

     -    Clinical rationale (preliminary) for product profile

     -    Alliance Opportunity assessment

     -    Intellectual property assessment

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 3.2.4
                                EXCLUDED TARGETS

                 GENBANK ACCESSION NUMBER (AMINO ACID SEQUENCE)

***

<PAGE>

                                                                  EXECUTION COPY

                                   EXHIBIT 4.4
                       ADVERSE EVENT REPORTING PROCEDURES

The terms adverse event or experience (AE) and adverse drug reaction (ADR), used
in this Exhibit 4.4 shall have the meanings set forth in worldwide reporting
regulations. The Parties agree to comply with any and all governmental laws,
regulations and orders that are applicable now and in the future in connection
with product safety collection and reporting.

The Parties agree to meet after the Effective Date to establish a detailed
Safety Agreement outlining the pharmacovigilance responsibilities of each Party
including but not limited to: AE or ADR reporting including literature review
and associated reporting; AE or ADR follow-up reporting; preparation and
submission of all safety reports to the Regulatory Authorities as required by
local laws and/or regulations in the Territory; maintaining the global safety
database; all interactions with health authorities regarding safety; periodic
submissions; labeling modifications; safety monitoring and detection; and safety
measures (e.g., Dear Doctor Letter, restriction on distribution). Wyeth shall
maintain the global safety database for the Licensed Products.

Notwithstanding the foregoing and until such time as the Safety Agreement is
executed, to the extent Trubion has or receives any information regarding any
AE/ADR which may be related to the use of any Licensed Product or to Licensed
Product Development, Trubion shall promptly forward such information as follows:

     -    Fatal or life-threatening serious AE(s)/ADR(s) judged by either the
          investigator and/or sponsor to be reasonably related to the Licensed
          Product(s) Development/protocol shall be transmitted to Wyeth within
          three (3) calendar days from the date received by Trubion.

     -    All other serious AE(s)/ADR(s) not fatal or life-threatening but
          judged by either the investigator and/or sponsor to be reasonably
          related to the Licensed Product(s) Development/protocol shall be
          transmitted to Wyeth within five (5) calendar days from the date
          received by Trubion.

AE/ADR information may be transmitted to Wyeth by:

     a. Facsimile: 610-989-5544 OR

     b. Overnight courier to:

          Global Safety Surveillance & Epidemiology
          Wyeth Research
          GSSE Triage Unit
          Dock E
          500 Arcola Road
          Collegeville, PA 19426

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 5.2A
                            STOCK PURCHASE AGREEMENT

                          TRUBION PHARMACEUTICALS, INC.

                         COMMON STOCK PURCHASE AGREEMENT

          This Common Stock Purchase Agreement (this "Agreement") is made as of
December __, 2005 by and between Trubion Pharmaceuticals, Inc., a Delaware
corporation (the "Company"), and Wyeth, a Delaware corporation (the
"Purchaser").

                                    RECITALS

          A. The Purchaser and the Company are entering into a collaboration
agreement of even date herewith (the "Collaboration Agreement");

          B. In connection with the Collaboration Agreement, Purchaser desires
to purchase from the Company shares of its Common Stock (the "Common Stock"),
concurrently with and conditioned upon the closing of the Company's initial
public offering, upon the terms and conditions set forth herein;

          C. The Company and the Purchaser wish to set forth the terms and
conditions upon which the Company will sell the Common Stock to the Purchaser;
and

          D. Concurrent with the execution of this Agreement, the Company and
Purchaser are entering into an amendment (the "Rights Agreement Amendment") to
the Company's Amended and Restated Investor Rights Agreement (the "Rights
Agreement") to provide Purchaser with certain rights and obligations thereunder
upon the issuance of the Common Stock hereunder.

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

                                    ARTICLE I

                           PURCHASE AND SALE OF SHARES

     1.1 Purchase Price and Closing. Subject solely to the conditions set forth
in Sections 1.2 - 1.5 and Article IV hereof, the Company will issue and sell to
the Purchaser and, subject to the terms and conditions set forth in this
Agreement, the Purchaser will purchase from the Company (the "Sale"), that
number of shares of Common Stock (the "Shares") equal to the quotient obtained
by dividing Twenty-Five Million Dollars ($25,000,000) (the "Investment Amount")
by the per-share price to the public (the "IPO Price") of shares of Common Stock
in the Company's first underwritten, firm commitment public offering (the "IPO")
pursuant to an effective registration statement (the "Registration Statement")
under the Securities Act of 1933, as amended (the "Securities Act"). The per
share price to Purchaser shall be the IPO Price. The purchase and sale will take
place at a closing (the "Closing") to be held on the date, at the location and
simultaneously with the closing of the IPO, subject to the satisfaction of all
of the conditions to the Closing specified in Article IV herein. At the Closing
the Company will issue and deliver a certificate evidencing the Shares to the
Purchaser against payment of the full purchase price therefor by wire transfer
of immediately available funds to an account designated by the Company.

<PAGE>

     1.2 Maximum Share Number. Notwithstanding Section 1.1 above, in the event
the number of Shares would otherwise constitute more than (i) nineteen and
nine-tenths percent (19.9%) of the Actual Voting Power (as defined in Section
5.1(i)) or (ii) twenty percent (20%) of the number of shares issued in the IPO
(including any shares covered by a related registration statement filed pursuant
to Rule 462(b) of the Securities Act but excluding any shares issued or to be
issued in an overallotment option), then in either case (i) or (ii) above the
Investment Amount (and correspondingly the number of shares purchased by the
Purchaser) shall be reduced by the minimum dollar amount and share amount
necessary to avoid either such event.

     1.3 Restrictions on Transfer. Pursuant to the Rights Agreement Amendment,
Purchaser agrees and acknowledges that the restrictions set forth in Sections
2.1 and 2.12 of the Rights Agreement shall apply to Purchaser and the Shares.

     1.4 HSR Act. Prior to the execution of the Collaboration Agreement and this
Agreement, the parties made certain filings under the Hart-Scott Rodino
Antitrust Improvements Act of 1976, as amended (the "HSR Act"). If either party
concludes in good faith that additional filings or proceedings are necessary or
desirable as a result of the transactions contemplated hereby either as a result
of the signing of this Agreement or in connection with the Closing or otherwise,
the parties agree to promptly file such additional notices, applications and
documents that may be required under the HSR Act, or any other required foreign
or domestic competition law (collectively, the "Competition Laws") and all
applicable additional filings fees associated therewith shall be paid by the
party required to so pay such additional filing fees under the applicable
Competition Law(s). In connection therewith, the Company and Purchaser each
shall use their commercially reasonable efforts to take such actions as may be
required to cause the expiration or early termination of the notice periods
under the Competition Laws as promptly as possible and to resolve such
objections, if any, as may be asserted with respect to the transactions
contemplated by this Agreement under the Competition Laws; provided, however,
that notwithstanding the foregoing, neither party shall agree to any change or
amendment to this Agreement unless such change or amendment is agreed by the
other party in advance. Nothing in this Agreement shall require either party or
any subsidiary or affiliate of either party to sell, hold separate, license or
otherwise dispose of any assets or conduct its business in a specified manner,
or agree or proffer to sell, hold separate, license or otherwise dispose of any
assets or conduct its business in a specified manner, or permit or agree to the
sale, holding separate, licensing or other disposition of any assets of either
party or any subsidiary or affiliate of either party, whether as a condition to
obtaining any approval from, or to avoid potential litigation or administrative
action by, a governmental entity or any other person or for any other reason.

     1.5 Termination of Purchase Right and Obligation. Notwithstanding any
provision of this Agreement to the contrary, Purchaser's right and obligation to
purchase, and the Company's right and obligation to sell, the Shares shall
terminate if the closing of the IPO has not occurred prior to the earliest to
occur of the following:

          (a) The termination of the Collaboration Agreement; or

          (b) The Company (1) undergoes a Change of Control (as defined in
Section 5.1(iv));; provided, however, the following shall be deemed to not be a
Change of Control for purposes of this Section 1.5(b): (i) a transaction
effected exclusively for the purpose of changing the domicile of the Company, or
(ii) an equity financing in which the Company is the surviving corporation, or
(2) engages in a merger, consolidation, reorganization or similar transaction in
which the surviving entity has a class of equity securities registered under
Section 12 of the Exchange Act (as defined below).

                                       2
<PAGE>

                                   ARTICLE II

                  REPRESENTATIONS AND WARRANTIES OF THE COMPANY

     The Company hereby represents and warrants to the Purchaser as follows:

     2.1 Corporate Action. The Company has all necessary corporate power and has
taken all corporate action required to enter into and perform this Agreement and
the Rights Agreement Amendment (collectively, the "Financing Documents"). The
Financing Documents have been duly executed and delivered, and constitute valid,
legal, binding and enforceable obligations of the Company, enforceable in
accordance with their terms, except (i) as limited by applicable bankruptcy,
insolvency, reorganization, moratorium and other laws of general application
affecting enforcement of creditors' rights generally and (ii) as limited by laws
relating to the availability of specific performance, injunctive relief or other
equitable remedies. The issuance, sale and delivery of the Shares in accordance
with this Agreement have been duly authorized by all necessary corporate action
on the part of the Company. The issuance of the Shares is not subject to
preemptive rights or other preferential rights in any present stockholders of
the Company that have not been waived and will not conflict with any provision
of any agreement or instrument to which the Company is a party or by which it or
its property is bound and to which the Company has not obtained appropriate
waivers.

     2.2 No Conflict. The execution and delivery of this Agreement by the
Company does not, and the consummation of the transactions contemplated hereby
will not, conflict with, or result in any violation of, or default under (with
or without notice or lapse of time, or both), or give rise to a right of
termination, cancellation, modification or acceleration of any obligation under
(i) any provision of the Certificate of Incorporation of the Company or Bylaws
of the Company, (ii) any material mortgage, indenture, lease, contract or other
agreement or instrument, permit, concession, or license to which the Company or
any of its properties or assets is subject or (iii) any judgment, order, decree,
applicable to the Company or its properties or assets. To the Company's
knowledge as of the date hereof, no provision of any applicable law, rule or
regulation and no judgment, order, decree or injunction applicable to the
Company or its properties or assets shall prohibit the consummation of the
Closing nor shall the Closing result in any violation of any such law, rule,
regulation, judgment, order, decree or injunction.

     2.3 Status of Shares. The Shares, when issued and delivered in accordance
with the terms hereof and after payment of the purchase price therefor, will be
duly authorized, validly issued, fully-paid and non-assessable, issued in
compliance with applicable state and federal securities laws (subject, in part,
to the representations and warranties of Purchase in Article III hereof) and
free of restrictions on transfer other than restrictions on transfer under the
Financing Documents and applicable state and federal securities laws.

     2.4 Organization, Good Standing and Qualification. The Company is a
corporation duly organized, validly existing and in good standing under the laws
of the State of Delaware and has all requisite corporate power and authority to
carry on its business.

     2.5. Collaboration Agreement. The Collaboration Agreement has been duly
authorized, executed, and delivered by the Company and constitutes a valid and
binding obligation of the Company, enforceable in accordance with its terms,
except (i) as limited by applicable bankruptcy, insolvency, reorganization,
moratorium and other laws of general application affecting enforcement of
creditors' rights generally and (ii) as limited by laws relating to the
availability of specific performance, injunctive relief or other equitable
remedies.

                                       3

<PAGE>

     2.6 Final Prospectus and Registration Statement. The Company, acknowledging
that the Purchaser will be relying on the accuracy and completeness of the
Company's disclosure in connection with the IPO, warrants to the Purchaser that
the Prospectus (as defined below) used in connection with the Company's IPO will
comply, at the time of filing or use, with the requirements of the Securities
Act, and the Prospectus filed or used in connection with the IPO will not, at
such time, contain an untrue statement of a material fact or omit to state a
material fact required to be stated therein or necessary to make the statements
therein, in light of the circumstances under which they were made, not
misleading; the Registration Statement, when it becomes effective, will comply,
in all material respects, with the requirements of the Securities Act; and the
Registration Statement will not, when it becomes effective, contain an untrue
statement of a material fact or omit to state a material fact required to be
stated therein or necessary to make the statements therein; provided, however,
that the Company makes no warranty with respect to any statement contained in
the Registration Statement or a prospectus in reliance upon and in conformity
with information concerning the Purchaser that is furnished by the Purchaser
expressly for use therein. "Prospectus" means the final prospectus (as such term
is defined in Section 2(a)(10) of the Securities Act) as first filed with the
SEC pursuant to paragraph (1) or (4) of Rule 424(b) of the Securities Act.

                                   ARTICLE III

            REPRESENTATIONS AND WARRANTIES AND COVENANTS BY PURCHASER

     The Purchaser represents and warrants and covenants to the Company that:

     3.1 Purchaser is an "accredited investor" as defined in Rule 501(a) under
the Securities Act of 1933, as amended.

     3.2 Purchaser will acquire the Shares for its own account, for the purpose
of investment and not with a view to distribution or resale thereof.

     3.3 Purchaser has all necessary corporate power and has taken all corporate
action required to enter into and perform the Financing Documents. The Financing
Documents have been duly executed and delivered, and constitute valid, legal,
binding and enforceable obligations of Purchaser, enforceable in accordance with
their terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium and other laws of general application affecting
enforcement of creditors' rights generally and (ii) as limited by laws relating
to the availability of specific performance, injunctive relief or other
equitable remedies.

     3.4 Purchaser has taken no action which would give rise to any claim
against the Company by any other person for any brokerage commissions, finders'
fees or the like relating to this Agreement or the transactions contemplated
hereby.

     3.5 Purchaser has had the opportunity to ask questions of and receive
answers from representatives of the Company concerning the terms of the offering
of the Shares and to obtain additional information concerning the Company and
its business.

     3.6 The acquisition by the Purchaser of the Shares shall constitute a
confirmation of these representations and warranties made by the Purchaser as of
the Closing. Purchaser understands that the Shares are "restricted securities"
under the Securities Act and have not been registered under the Securities Act
in reliance upon an exemption for non-public offerings. The Purchaser further
represents that it understands and agrees that, until registered under the
Securities Act or transferred pursuant to the provisions of Rule 144 as
promulgated by the Commission, all certificates evidencing any of the Shares,

                                       4

<PAGE>

whether upon initial issuance or upon any transfer thereof, shall be subject to
the transfer restrictions and bear the legends set forth in Section 2.1 of the
Rights Agreement.

     3.7 To the Purchaser's knowledge as of the date hereof, no provision of any
applicable law, rule or regulation and no judgment, order, decree or injunction
applicable to the Purchaser or its properties or assets shall prohibit the
consummation of the Closing nor shall the Closing result in any violation of any
such law, rule, regulation, judgment, order, decree or injunction.

                                   ARTICLE IV

                              CONDITIONS TO CLOSING

     4.1 Conditions of the Purchaser's Obligation. The obligation of the
Purchaser to purchase and pay for the Shares at the Closing is subject to the
satisfaction of the following conditions:

          (a) Documentation at Closing. The Purchaser shall have received prior
to or at the Closing all of the following documents or instruments, or evidence
of completion thereof, each in form and substance satisfactory to the Purchaser:

               (i) A copy of the Certificate of Incorporation of the Company,
certified by the Secretary of State of the State of Delaware, a copy of the
resolutions of the Board of Directors of the Company evidencing the approval of
this Agreement, the issuance of the Shares and the other matters contemplated
hereby, and a copy of the Bylaws of the Company, all of which shall have been
certified by the Secretary of the Company to be true, complete and correct in
every particular, and certified copies of all documents evidencing other
necessary corporate or other action and governmental approvals, if any, with
respect to this Agreement and the Shares.

               (ii) A customary opinion of counsel to the Company covering the
matters set forth in Exhibit A hereto.

               (iii) A certificate of the Secretary of the Company which shall
certify the names of the officers of the Company authorized to sign this
Agreement, the certificate for the Shares and the other documents, instruments
or certificates to be delivered pursuant to this Agreement by the Company or any
of its officers, together with the true signatures of such officers.

               (iv) A certificate of the President of the Company stating (A)
that the representations and warranties made by the Company in this Agreement
are true and correct in all material respects at the date hereof and as of the
Closing with the same force and effect as though all such representations and
warranties had been made as of the Closing, and (B) that all covenants and
conditions required to be performed prior to or at the Closing have been
performed as of the Closing.

               (v) A Certificate of Good Standing for the Company from the
Secretary of State of the State of Delaware, dated as of a recent date.

          (b) Performance. The Company shall have performed and complied with in
all material respects all agreements, obligations and conditions contained in
this Agreement that are required to be performed or complied with by it on or
before the Closing.

          (c) Consents, Waivers, Etc. The Company shall have obtained all
consents or waivers, if any, necessary to execute and deliver this Agreement,
issue the Shares and to carry out the transactions contemplated hereby and
thereby and the waiting period applicable to this Agreement and the

                                       5

<PAGE>

Collaboration Agreement under the HSR Act (or any other applicable Competition
Laws) shall have expired or terminated early. All corporate and other action and
governmental filings necessary to effect the terms of this Agreement, the
issuance of the Shares and other agreements and instruments executed and
delivered by the Company in connection herewith shall have been made or taken,
except for any post-sale filing that may be required under federal or state
securities laws.

          (d) Rights Agreement Amendment. The Rights Agreement Amendment shall
have been executed by the Company and by the holders of the requisite majority
of Registrable Securities (as such term is defined in the Rights Agreement);
provided, however, the parties acknowledge that subsequent to the date hereof
the Rights Agreement may be further amended in accordance with its terms;
provided, further, however, Purchaser shall be required to consent to such
amendment or be provided substantially equivalent rights in such amendment or
another written agreement with the Company.

          (e) Collaboration Agreement. The Collaboration Agreement shall have
been duly authorized, executed, and delivered by the Company and constitute a
valid and binding obligation of the Company, enforceable in accordance with its
terms, except (i) as limited by applicable bankruptcy, insolvency,
reorganization, moratorium and other laws of general application affecting
enforcement of creditors' rights generally and (ii) as limited by laws relating
to the availability of specific performance, injunctive relief or other
equitable remedies. The Purchaser shall not have the right to terminate the
Collaboration Agreement for cause pursuant to Section 9.5 thereof (provided,
however, if Purchaser's right to so terminate the Collaboration Agreement for
cause is solely dependent on the lapsing on any applicable "cure" period
pursuant to Section 9.5 thereof, solely for purposes of this Section 4.1(e),
Purchaser shall be deemed to have the right to terminate the Collaboration
Agreement for cause notwithstanding the failure of any such cure period to have
lapsed); and the Company shall not have given notice to the Purchaser of its
intent to terminate the Collaboration Agreement.

          (f) Representations and Warranties. The representations and warranties
made by the Company in this Agreement shall have been true and correct in all
material respects at the date hereof and as of the Closing with the same force
and effect as though all such representations and warranties had been made as of
the Closing.

          (g) No Injunctions. No provision of any applicable law, rule or
regulation and no judgment, order, decree or injunction shall prohibit the
consummation of the Closing.

          (h) Listing. The shares of Common Stock sold in the IPO shall be
listed on the New York Stock Exchange ("NYSE") or traded on the Nasdaq National
Market.

          (i) Closing of IPO. The Closing hereunder shall be concurrent with the
closing of the IPO.

     4.2 Conditions of the Company's Obligation. The obligation of the Company
to sell the Shares at the Closing is subject to the satisfaction of the
following conditions:

          (a) Performance. The Purchaser shall have performed and complied with
in all material respects all agreements, obligations and conditions contained in
this Agreement that are required to be performed or complied with by it on or
before the Closing.

          (b) Consents, Waivers, Etc. Any waiting period applicable to this
Agreement and the Collaboration Agreement under the HSR Act (or any other
applicable Competition Laws) shall have expired or terminated early.

                                       6

<PAGE>

          (c) Rights Agreement Amendment. The Rights Agreement Amendment shall
have been executed by the Purchaser.

          (d) Collaboration Agreement. The Collaboration Agreement shall have
been duly authorized, executed and delivered by the Purchaser and constitute a
valid and binding obligation of the Purchaser, enforceable in accordance with
its terms, subject to laws of general application relating to bankruptcy,
insolvency and the relief of debtors and rules of law governing specific
performance, injunctive relief or other equitable remedies. The Company shall
not have the right to terminate the Collaboration Agreement for cause pursuant
to Section 9.5 thereof (provided, however, if the Company's right to so
terminate the Collaboration Agreement for cause is solely dependent on the
lapsing on any applicable "cure" period pursuant to Section 9.5 thereof, solely
for purposes of this Section 4.2(d), the Company shall be deemed to have the
right to terminate the Collaboration Agreement for cause notwithstanding the
failure of any such cure period to have lapsed; and the Purchaser shall not have
given notice to the Company of its intent to terminate the Collaboration
Agreement.

          (e) Representations and Warranties. The representations and warranties
made by the Purchaser in this Agreement shall have been true and correct in all
material respects at the date hereof and as of the Closing with the same force
and effect as though all such representations and warranties had been made as of
the Closing.

          (f) No Injunctions; Applicable Law. No provision of any applicable
law, rule or regulation and no judgment, order, decree or injunction shall
prohibit the consummation of the Closing nor shall the Closing result in any
violation of any such law, rule, regulation, judgment, order, decree or
injunction.

          (g) Listing. The shares of Common Stock sold in the IPO shall be
listed on the NYSE or traded on the Nasdaq National Market.

          (h) Closing of IPO. The Closing hereunder shall be concurrent with the
closing of the IPO.

          (i) Securities Regulations. The sale of the Shares to Purchaser shall
not be prohibited under state and federal securities laws and regulations.

                                    ARTICLE V

                              STANDSTILL AGREEMENT

     5.1. Definitions. For the purposes of this Agreement, the following words
and phrases shall have the following meanings:

          (i) "Actual Voting Power" means, as of the date of determination, the
total number of votes attaching to the outstanding securities entitled to vote
for the election of directors of the Company.

          (ii) "Affiliate" shall have the meaning given it in Rule 12b-2 under
the Securities Exchange Act of 1934, as amended (the "Exchange Act").

          (iii) "Beneficial Ownership" "Beneficial Owner" and "Beneficially Own"
shall have the meanings described to those terms in Rule 13d-1 under the
Exchange Act.

                                       7

<PAGE>

          (iv) "Change of Control" means (1) the acquisition by a Third Party of
more than 50% of the Company's then outstanding Voting Securities or (2) the
consummation of a merger, acquisition, consolidation or reorganization or series
of such related transactions involving the Company, unless immediately after
such transaction or transactions, the Beneficial Owners of the Company
immediately prior to the first such transaction shall Beneficially Own at least
50% of the outstanding Voting Securities of the Company (or, if the Company
would not be the surviving company in such merger, consolidation or
reorganization, the Voting Securities of the surviving corporation issued in
such transaction or transactions in respect of Voting Securities of the Company
shall represent at least 50% of the Voting Securities of such surviving
company).

          (v) "Investor Group" means Purchaser and any member of a 13D Group to
which the Purchaser belongs.

          (vi) "Person" means an individual, corporation, partnership,
association, trust, unincorporated organization or other entity

          (vii) "13D Group" means any group of persons formed for the purpose of
acquiring, holding, voting or disposing of Voting Securities which would be
required under the Exchange Act and the rules and regulations promulgated
thereunder, to file a statement on Schedule 13D with the Securities and Exchange
Commission as a "person" within the meaning of Section 13(d)(3) of the Exchange
Act if such group beneficially owned sufficient securities to require such a
filing under the Exchange Act.

          (viii) "Standstill Period" shall mean the period beginning on the
Closing of the IPO and ending on the date that is one year following the Closing
of the IPO.

          (ix) "Threshold Percentage" means the percentage of Actual Voting
Power owned by the Purchaser immediately following the closing of the IPO and
the sale of Shares hereunder, which in no case shall exceed nineteen and
nine-tenths percent (19.9%) of Actual Voting Power.

          (x) "Third Party" means any Person or two or more Persons acting in
concert, other than the Purchaser and its Affiliates or the Company and its
Affiliates.

          (xii) "Voting Security" means, as of the date of determination, the
Common Stock of the Company, any other security generally entitled to vote for
the election of directors and any outstanding convertible securities, options,
warrants or other rights which are convertible into or exchangeable or
exercisable for securities entitled to vote for the election of directors.

     5.2. Standstill Obligations.

          (a) Limitation. At any time during the Standstill Period, except with
the prior written consent of the Company's Board of Directors, no member of the
Investor Group shall, directly or indirectly:

               (i) acquire any Voting Securities (except by way of stock splits,
stock dividends or other distributions) if the effect of such acquisition or
exercise would be to increase the percentage interest of the Investor Group in
the Actual Voting Power to more than the Threshold Percentage; or

               (ii) publicly propose (on behalf of itself or to or with a Third
Party) any merger, business combination, restructuring, recapitalization or
similar transaction involving the Company or its subsidiaries or the purchase,
sale or other disposition outside the ordinary course of business of any
material portion of the assets of the Company or any of its subsidiaries.

                                       8

<PAGE>

          (b) Repurchases. Notwithstanding Section 5.2(a), no member of the
Investor Group shall be obligated to dispose of any Voting Securities if the
aggregate percentage ownership of the Investor Group is increased as a result of
a repurchase of Voting Securities by the Company.

          (c) Participation. Except with the prior written consent of the
Company's Board of Directors, during the Standstill Period the Investor Group
will not:

               (i) solicit proxies (or powers of attorney or similar rights to
vote) in respect of any Voting Securities;

               (ii) become a "participant" or "participant in a solicitation",
as those terms are defined in Regulation 14A of the General Rules and
Regulations promulgated pursuant to the Exchange Act, in opposition to a
solicitation by the Company; provided, however, that the Investor Group shall
not be deemed to be a "participant" or to have become engaged in a solicitation
hereunder solely by reason of the Company's solicitation of proxies in
connection with any meeting of the stockholders of the Company;

               (iii) seek to advise or intentionally influence any person or
entity with respect to the voting of Voting Securities in connection with any
such solicitation, in opposition to the recommendation of a majority of the
Board of Directors with respect to any matter relating to a Change of Control;

               (iv) initiate, propose or otherwise solicit stockholders for the
approval of any stockholder proposal (as described in Rule 14a-8 under the
Exchange Act or otherwise) with respect to the Company that is opposed by the
Board of Directors;

               (v) form or join any 13D Group for the purpose of voting,
purchasing or disposing of Voting Securities or the acquisition of all or
substantially all of assets of the Company;

               (vi) deposit any Voting Securities in a voting trust or subject
them to a voting agreement or other arrangement of similar effect, except in
order to comply with Competition Laws or other legal requirements;

               (vii) otherwise act, alone or in concert with others, in a manner
designed or having the deliberate effect of circumventing the restrictions
otherwise imposed hereunder, publicly announce any intention, plan or
arrangement inconsistent with the foregoing or finance or agree to finance any
other person in connection with any of the activities prohibited by this
Agreement; or

               (viii) publicly request, propose or otherwise seek any amendment
or waiver of the provisions of this Article 5.

     5.3 Exceptions. The limitations provided in Section 5.2 shall immediately
terminate upon the occurrence of any of the following events:

          (a) the commencement by any Person (other than a member of the
Investor Group or an Affiliate thereof) of a bona fide tender or exchange offer
seeking to acquire Beneficial Ownership of fifty percent (50%) or more of the
outstanding shares of Voting Securities of the Company;

          (b) the execution of an agreement by the Company and any Person which,
if consummated, would result in either (i) a Change of Control of the Company or
(ii) the sale of all or substantially all of the Company's assets; or

                                       9

<PAGE>

          (c) the adoption by the Company of a plan of liquidation or
dissolution with respect to the Company.

     5.4 Exclusion. No action or actions taken by the Purchaser pursuant to the
terms of the Collaboration Agreement or in connection with exercising or
enforcing its rights thereunder shall be deemed to violate the restrictions in
Section 5.2.

                                   ARTICLE VI

                                  MISCELLANEOUS

     6.1 No Waiver. No failure or delay on the part of any party to this
Agreement in exercising any right, power or remedy hereunder shall operate as a
waiver thereof; nor shall any single or partial exercise of any such right,
power or remedy preclude any other or further exercise thereof or the exercise
of any other right, power or remedy hereunder. None of the terms, covenants and
conditions of this Agreement can be waived except by the written consent of the
party waiving compliance.

     6.2 Publicity. The parties may, subject to compliance with the Securities
Act, issue a joint press release announcing this Agreement and the transactions
contemplated hereby following execution of this Agreement. Any proposed
announcement, press release or other public disclosure concerning this Agreement
and/or any of the transactions or relationships contemplated hereby shall be
mutually approved by both parties (which approval shall not be unreasonably
withheld); provided, however, that the restrictions contained in this Section
6.2 do not apply to disclosures required by law, the rules of the NYSE, the NASD
or under U.S. generally accepted accounting principles. The Purchaser agrees and
acknowledges that this Agreement and the transactions contemplated hereby shall
be disclosed in, and filed as an exhibit to, the Registration Statement.

     6.3 Amendments, Waivers and Consents. Any provision in this Agreement to
the contrary notwithstanding, and except as hereinafter provided, changes in or
additions to this Agreement may be made, and compliance with any covenant or
provision set forth herein may be omitted or waived, if the party requesting
such change, addition, omission or waiver shall obtain consent thereto in
writing from the other party. Any waiver or consent may be given subject to
satisfaction of conditions stated therein and any waiver or consent shall be
effective only in the specific instance and for the specific purpose for which
given. Any such amendment or waiver or consent effected in accordance with this
Section 6.3 shall be binding upon the parties and their respective successors
and assigns.

     6.4 Addresses for Notices. Any notice required or permitted by this
Agreement shall be in writing and shall be deemed sufficient upon receipt, when
delivered personally or by courier, overnight delivery service or confirmed
facsimile, or seventy-two (72) hours after being deposited in the regular mail
as certified or registered mail (airmail if sent internationally) with postage
prepaid, if such notice is addressed to the party to be notified at such party's
address or facsimile number as set forth below, or as subsequently modified by
written notice.

     If to the Company:

          Trubion Pharmaceuticals, Inc.
          2401 Fourth Avenue, Suite 1050
          Seattle, WA 98121
          Attn: Chief Executive Officer and General Counsel
          Facsimile Number: (206) 838-0503

                                       10

<PAGE>

     If to the Purchaser:

          Wyeth Pharmaceuticals
          500 Arcola Road
          Collegeville, Pennsylvania 19426
          Attn: Senior Vice President, Corporate Business Development
          Fax: (484) 865-6476

          with a copy to:

          Wyeth
          5 Giralda Farms
          Madison, NJ 07940
          Attn: Executive Vice President and General Counsel
          Facsimile: (973) 660-7156

     6.5 Binding Effect; Assignment. This Agreement may not be assigned by
either party without the prior written consent of the other; provided, however,
that the Purchaser may assign its rights and delegate its duties hereunder to an
Affiliate without the prior written consent of the Company; provided, however,
Purchaser shall remain subject to Section 5 hereof regardless of any such
assignment; and provided further that if the Company undergoes a Change of
Control in which (a) the Company is not the surviving entity and (b) this
Agreement does not terminate pursuant to Section 1.5(b) in connection with such
Change of Control, the surviving entity and the Purchaser shall enter into a
replacement agreement with substantially the same terms as this Agreement.
Subject to the foregoing, the terms and conditions of this Agreement shall inure
to the benefit of and be binding upon the respective successors and assigns of
the parties. Nothing in this Agreement, express or implied, is intended to
confer upon any party other than the parties hereto or their respective
successors and assigns any rights, remedies, obligations, or liabilities under
or by reason of this Agreement, except as expressly provided in this Agreement.

     6.6 Entire Agreement. This Agreement and the documents referred to herein
constitute the entire agreement between the parties and supersede any prior
understandings or agreements concerning the subject matter hereof.

     6.7 Specific Performance. The parties acknowledge and agree that
irreparable damage would occur in the event any of the provisions of Article V
of this Agreement were not performed in accordance with their specific terms or
were otherwise breached. Accordingly, it is agreed that the parties shall be
entitled to an injunction or injunctions to prevent or cure breaches of the
provisions of Article V of this Agreement and to enforce specifically the terms
and provisions of such Article in any court of the United States or any state
thereof having jurisdiction, in addition to any other remedy to which they may
be entitled in law or in equity.

     6.8 Severability. The provisions of this Agreement are severable and, in
the event that any court of competent jurisdiction shall determine that any one
or more of the provisions or part of a provision contained in this Agreement
shall, for any reason, be held to be invalid, illegal or unenforceable in any
respect, such invalidity, illegality or unenforceability shall not affect any
other provision or part of a provision of this Agreement; but this Agreement,
shall be reformed and construed as if such invalid or illegal or unenforceable
provision, or part of a provision, had never been contained herein, and such
provisions or part reformed so that it would be valid, legal and enforceable to
the maximum extent possible.

                                       11

<PAGE>

     6.9 Governing Law. This Agreement shall be governed by, and construed and
enforced in accordance with, the laws of the State of Delaware without reference
to Delaware conflicts of law provisions.

     6.10 Headings. Article, Section and subsection headings in this Agreement
are included herein for convenience of reference only and shall not constitute a
part of this Agreement for any other purpose.

     6.11 Counterparts. This Agreement may be executed in any number of
counterparts, each of which shall be enforceable against the party actually
executing the counterpart, and all of which together shall constitute one
instrument.

                            [Signature page follows.]

                                       12

<PAGE>

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

                                        TRUBION PHARMACEUTICALS, INC.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

                                        WYETH

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Title:
                                               ---------------------------------

<PAGE>

                                                                       EXHIBIT A

                    MATTERS TO BE COVERED BY COMPANY COUNSEL

     1. The Company is a corporation validly existing under Delaware law and in
good standing with the Secretary of the State of Delaware and has the corporate
power to execute and deliver the Agreement and to perform its obligations
thereunder.

     2. The Company has duly authorized, executed and delivered the Agreement,
and the Agreement constitutes the Company's valid and binding agreement
enforceable against the Company in accordance with its terms, except as
enforceability may be limited by bankruptcy, insolvency, reorganization,
moratorium or similar laws relating to or affecting creditors' rights generally
or by general equitable principles.

     3. No consent, approval, authorization or order of, or any filing or
declaration with, any court or governmental agency or body is required in
connection with the execution, delivery and performance of the Agreement by the
Company or in connection with the taking by the Company of any action
contemplated thereby, other than as indicated in the Agreement or such as have
been obtained and made and such as may be required under federal and state
securities laws.

     4. The execution, delivery and performance of the Agreement by the Company,
and the consummation by the Company of the transactions contemplated therein do
not and will not (a) violate the Certificate of Incorporation or By-Laws of the
Company, (b) materially violate any judgment, ruling, decree or order known to
such counsel, (c) materially violate any statute or regulation applicable to the
business or properties of the Company, or (d) result in a material breach or
violation of any of the terms or provisions of, or constitute a default or
result in the acceleration of any obligation under any material contract to
which the Company is a party or bound.

     5. The Shares delivered on the date hereof have been duly authorized and
validly issued and are fully paid and non-assessable shares of the Company.

<PAGE>

                                                                  EXECUTION COPY

                                  EXHIBIT 5.2B

                          TRUBION PHARMACEUTICALS, INC.

                               AMENDMENT NO. 1 TO

                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

     This Amendment No. 1 to the Amended and Restated Investor Rights Agreement
(the "RIGHTS AGREEMENT") dated as of July 13, 2004 is entered into as of
________, 2005, by and among Trubion Pharmaceuticals, Inc., a Delaware
corporation (the "COMPANY"), Wyeth, a Delaware corporation ("WYETH"), and the
investors set forth on EXHIBIT A hereto (collectively the "INVESTORS" and each
individually an "INVESTOR").

                                    RECITALS

     A. The Company and the Investors are parties to the Rights Agreement.

     B. The Company and Wyeth have entered into a Common Stock Purchase
Agreement dated as of December __, 2005 (the "PURCHASE AGREEMENT") pursuant to
which the Company will sell to Purchaser and Purchaser will purchase from the
Company shares of the Company's Common Stock concurrent with and conditioned
upon the closing of the Company's initial public offering (the "CLOSING"). A
condition to the Purchaser's obligations under the Purchase Agreement is that
the Rights Agreement be amended in order to provide Purchaser with certain
rights to register shares of the Company's Common Stock.

     C. Pursuant to Section 6.5 of the Rights Agreement, the written consent of
the Company and the Investors holding a majority of the Registrable Securities
(the "REQUISITE HOLDERS") is required to amend the Rights Agreement.

     D. The Company and the Requisite Holders desire to induce Purchaser to
enter into the Purchase Agreement by agreeing to the terms and conditions set
forth herein.

     NOW, THEREFORE, in consideration of the mutual promises, representations,
warranties, covenants and conditions set forth in this Agreement, the parties
hereto agree as follows:

     1. Definitions. Capitalized terms used herein without definition shall have
the meaning ascribed to them in the Rights Agreement.

     2. Addition of Purchaser as a Party to the Rights Agreement. Effective upon
the Closing pursuant to the Purchase Agreement, the parties hereby agree to add
Purchaser as a party to the Rights Agreement and Purchaser shall be deemed a
"Holder" of Registrable Securities for purposes of Sections 1, 2 and 6 of the
Rights Agreement and subject to all of the rights and obligations of such
Sections. For purposes of clarification, Purchaser shall not be entitled to the
rights or subject to the obligations set forth in Sections 3, 4 and 5 of the
Rights Agreement and Purchaser shall not be deemed an "INVESTOR" for purposes of
the Rights Agreement.

<PAGE>

                                                                   REDUCTED COPY

     3. Amendment to Section 1.1. The definition of "Registrable Securities" set
forth in Section 1.1 is hereby amended and restated to read in its entirety as
follows:

          "REGISTRABLE SECURITIES" means (a) Common Stock of the Company issued
or issuable upon conversion of the Shares, (b) Common Stock of the Company
issued to Frazier Healthcare Fund ("FRAZIER"), ARCH Venture Fund ("ARCH") and
Scott Minick ("MINICK") pursuant to those certain Common Stock Purchase
Agreements dated November 19, 2002 by and between the Company and each of
Frazier, Arch and Minick, (c) Common Stock of the Company issued to Wyeth
pursuant to the Purchase Agreement, and (d) any Common Stock of the Company
issued as (or issuable upon the conversion or exercise of any warrant, right or
other security which is issued as) a dividend or other distribution with respect
to, or in exchange for or in replacement of, the securities described in (a),
(b) and (c) above; provided, however, the shares referred to in clause (c) above
shall not qualify as Registrable Securities for the purposes of Sections 2.2
hereof until the 15 month anniversary of the Closing. For the avoidance of
doubt, in the event that the Company effects a registration under the Securities
Act pursuant to Section 2.2 hereof prior to the 15 month anniversary of the
Closing, in connection with such registration the Shares referred to in clause
(c) above shall qualify as Registrable Securities for the purposes of Section
2.3. Notwithstanding the foregoing, Registrable Securities shall not include any
securities sold by a person to the public pursuant to a registration statement
or Rule 144 or sold in a private transaction in which the transferor's rights
under SECTION 2 of this Agreement are not assigned.

     4. Amendment to Section 2.1(a)(ii). Section 2.1(a)(ii) is amended effective
immediately following the expiration of the "Market Stand-Off" period set forth
in Section 2.12 hereof, by deleting the last sentence thereof and substituting
therefor the following:

     "Subject to the other terms of this Agreement (including without limitation
     the restrictions on assignment of registration rights set forth in Section
     2.10 and Sections 2.1(b) and (d)), it is agreed that the restrictions
     contained in this Section 2.1(a)(ii) shall not apply to dispositions of
     Shares or Registrable Securities made pursuant to Rule 144 promulgated
     under the Securities Act."

     5. Amendment to Section 6.5. Section 6.5 is hereby amended by adding, after
the final sentence thereof, the following:

          Notwithstanding the foregoing, neither this Agreement nor any term
hereof may be amended, waived, discharged or terminated in any way that
diminishes or eliminates the rights particular to Wyeth hereunder and in a
manner different than the other holders of Registrable Securities, such action
shall require the prior written consent of Wyeth.

     6. Waiver of Right of Participation. Each Investor on behalf of itself and
all other Investors and holders of Registrable Securities hereby waives any
right of participation set forth in Section IV of the Rights Agreement with
respect to the sale and issuance of the shares of Company Common Stock to Wyeth
pursuant to the Purchase Agreement.

     7. No Other Amendments. Except as expressly amended or waived as set forth
above, the Rights Agreement shall remain in full force and effect in accordance
with its terms.

     8. Counterparts. This Amendment may be executed in any number of
counterparts, each of which shall be deemed an original and all of which
together shall constitute one document.

                                      -2-

<PAGE>

                            [Signature pages follow.]

                                       -3-

<PAGE>

                                                                  EXECUTION COPY

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "COMPANY"

                                        TRUBION PHARMACEUTICALS, INC.
                                        a Delaware corporation

                                        By:
                                            ------------------------------------
                                            Peter Thompson, M.D., FACP
                                            President and Chief Executive
                                            Officer

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "WYETH"

                                        WYETH

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        PROSPECT VENTURE PARTNERS II, L.P.

                                        By: Prospect Management Co. II, LLC
                                        Its General Partner

                                        By:
                                            ------------------------------------
                                        Name: David Schnell
                                        Title: Managing Member

                                        PROSPECT ASSOCIATES II, L.P.

                                        By: Prospect Management Co. II, LLC
                                        Its General Partner

                                        By:
                                            ------------------------------------
                                        Name: David Schnell
                                        Title: Managing Member

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT
<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        VENROCK PARTNERS, L.P.
                                           by its General Partner, Venrock
                                           Partners Management, LLC

                                        VENROCK ASSOCIATES IV, L.P.
                                           by its General Partner, Venrock
                                           Management IV, LLC

                                        VENROCK ENTREPRENEURS FUND IV, L.P.
                                           by its General Partner, VEF
                                           Management IV, LLC

                                        By:
                                            ------------------------------------
                                        Name: Anders D. Hove
                                        Title: Member
                                        Address: 30 Rockefeller Plaza
                                                 Room 5508
                                                 New York, NY 10112

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

                                                                   REDUCTED COPY

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        ARCH VENTURE FUND V, L.P.

                                        By: ARCH Venture Partners V, L.P.
                                            Its general partner

                                        By: ARCH Venture Partners V, L.L.C.
                                            Its general partner

                                        By:
                                            ------------------------------------
                                        Title: Managing Director

                                        ARCH V ENTREPRENEURS FUND, L.P.

                                        By: ARCH Venture Partners V, L.P.
                                            Its general partner

                                        By: ARCH Venture Partners V, L.L.C.
                                            Its general partner

                                        By:
                                            ------------------------------------
                                        Title: Managing Director

                                        HEALTHCARE FOCUS FUND, L.P.

                                        By: ARCH Venture Partners V, L.P.
                                            Its general partner

                                        By: ARCH Venture Partners V, L.L.C.
                                            Its general partner

                                        By:
                                            ------------------------------------
                                        Title: Managing Director

                                        8

<PAGE>

                                                                  EXECUTION COPY

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        OXFORD BIOSCIENCE PARTNERS IV L.P.

                                        By: OBP Management IV L.P.

                                        By:
                                            ------------------------------------
                                            Mark P. Carthy - General Partner

                                        MRNA FUND II L.P.

                                        By: OBP Management IV L.P.

                                        By:
                                            ------------------------------------
                                            Mark P. Carthy - General Partner

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        FRAZIER HEALTHCARE IV, L.P.
                                        By FHM IV, LP, its general partner
                                        By FHM IV, LLC, its general partner

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                                        FRAZIER AFFILIATES IV, L.P.
                                        By FHM IV, LP, its general partner
                                        By FHM IV, LLC, its general partner

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                                        FRAZIER HEALTHCARE III, L.P.
                                        By FHM III, LLC

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                                        FRAZIER AFFILIATES III, L.P.
                                        By FHM III, LLC

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        ATP CAPITAL, L.P.

                                        By: ATP General Partner LLC
                                            Its General Partner

                                        By:
                                            ------------------------------------
                                            Jonathan Malkin, Manager

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

                                                                   REDUCTED COPY

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        CASCADE INVESTMENTS, L.L.C.

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                                        2

<PAGE>

                                                                  EXECUTION COPY

IN WITNESS WHEREOF, the parties hereto have executed this AMENDMENT NO. 1 TO THE
RIGHTS AGREEMENT as of the date set forth in the first paragraph hereof.

                                        "INVESTOR"

                                        ----------------------------------------

                                        By:
                                            ------------------------------------
                                        Name:
                                              ----------------------------------
                                        Its:
                                             -----------------------------------

                      SIGNATURE PAGE TO AMENDMENT NO. 1 TO
                 AMENDED AND RESTATED INVESTOR RIGHTS AGREEMENT

<PAGE>

                                                                  EXECUTION COPY

                                   EXHIBIT 5.3
                       ADDITIONAL RESEARCH AND DEVELOPMENT
                                EXPENSE PAYMENTS

A. ADDITIONAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENTS FOR CD20 PRODUCTS

Within *** after Trubion's or Wyeth's achievement of the following events with
respect to any *** (each payable one time only even if achieved with respect to
more than one ***), Wyeth shall make the following payments to Trubion:

***

B. ADDITIONAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENTS FOR ***

Within *** after Wyeth's achievement of the following events with respect to any
*** (each payable one time only even if completed or achieved with respect to
more than one ***), Wyeth shall make the following payments to Trubion:

***

C. ADDITIONAL RESEARCH AND DEVELOPMENT EXPENSE PAYMENTS FOR OTHER PRODUCTS

Within *** after Wyeth's achievement of the following events with respect to
each Other Product (up to a maximum of *** Other Products), Wyeth shall make the
following payments to Trubion; provided, however, that: (i) in the event that
any of the following events is achieved with respect to two or more Other
Products that are directed against the same Wyeth Target, such payment shall be
payable only with respect to the first such Other Product for which the event
occurred; and (ii) in the event that an Other Product is directed against two or
more Wyeth Targets, such Licensed Product shall be a Multispecific SMIP Product,
the consequences of which are as described in Section D below:

***

D. NO ADDITIONAL PAYMENTS; OTHER APPLICABLE TERMS AND CONDITIONS

(i) Other than the payments listed in Sections A - C of this Exhibit 5.3, no
Additional Research and Development Expense Payments shall be due or payable by
Wyeth to Trubion for any Licensed Product, regardless of the number of Licensed
Products Developed against any Trubion Target or Wyeth Target.

(ii) Each of the Additional Research and Development Expense Payments set forth
above shall be payable one time only with respect to each Licensed Target
(regardless

                                        2

<PAGE>

                                                                   REDUCTED COPY

of the number of times the specified event is achieved with respect to any
Licensed Product(s)).

(iii) In the event that the Development of a Licensed Product directed against a
particular Licensed Target hereunder (an "Initial Licensed Product") is
discontinued prior to the Commercialization of such Initial Licensed Product,
and Development has been initiated with respect to another Licensed Product
directed against such Licensed Target (a "Replacement Licensed Product"),
payments with respect to such Replacement Licensed Product shall be due under
this Exhibit 5.3 only upon the achievement of those events that have not been
achieved by the Initial Licensed Product.

***

(v) Subject to the limitations set forth above in Sections A, B and C and in
this Section D, if an Additional Research and Development Expense Payment based
on a clinical study of, or Regulatory Approval filing for, a Licensed Product
for a particular indication (a "Later Development Event") becomes payable before
the achievement of an earlier phase clinical study event with respect to such
Licensed Product for the same indication for which Additional Research and
Development Expense Payments would have been payable (an "Earlier Development
Event"), then the Additional Research and Development Expense Payment for the
Earlier Development Event also shall become payable upon occurrence of the Later
Development Event. ***

                                        3

<PAGE>

                                                                  EXECUTION COPY

                                 EXHIBIT 8.2(D)
                               THIRD PARTY RIGHTS

                           [INTENTIONALLY LEFT BLANK]

<PAGE>

                                                                  EXECUTION COPY

                                 EXHIBIT 8.2(E)
                          GOVERNMENT FUNDING AGREEMENTS

                            NIH GRANT # 5 R01 CA90143

      PROJECT TITLE: GENE THERAPY WITH MAB DERIVATIVES EXPRESSED ON TUMORS

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