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                                                                   EXHIBIT 10.11

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                       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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                                TABLE OF CONTENTS

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1.          DEFINITIONS..............................................................................................       1

2.          LICENSES.................................................................................................      17
            2.1         Licenses to Wyeth............................................................................      17
                        2.1.1       Exclusive Licenses...............................................................      17
                        2.1.2       Retained Rights of Trubion.......................................................      17
            2.2         License to Trubion...........................................................................      17
            2.3         Exclusivity..................................................................................      17
                        2.3.1       CD20 Product Exclusivity.........................................................      18
                        2.3.2       ***..............................................................................      18
                        2.3.3       Limitations......................................................................      18
            2.4         Sublicensing.................................................................................      19
            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.......................................................................      22
                        3.2.1       Target Candidates................................................................      22
                        3.2.2       Released Targets.................................................................      23
                        3.2.3       Wyeth Targets....................................................................      24
                        3.2.4       Excluded Targets.................................................................      25
            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.....................................................................      28
                        3.4.1       Composition......................................................................      28
                        3.4.2       Responsibilities.................................................................      28
                        3.4.3       Meetings.........................................................................      28
                        3.4.4       Voting...........................................................................      28
                        3.4.5       Dispute Resolution...............................................................      28
                        3.4.6       Minutes..........................................................................      29
            3.5         Research Plan................................................................................      29
            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............................................................................      32

4.          PRODUCT DEVELOPMENT, MANUFACTURING, COMMERCIALIZATION AND REGULATORY MATTERS.............................      32

            4.1         Product Development..........................................................................      32
            4.2         Transfer of Product Data and Filings.........................................................      33
            4.3         Regulatory Approvals.........................................................................      33
            4.4         Regulatory Reporting.........................................................................      34
            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................................................................................      37
            4.10        Commercialization............................................................................      37
            4.11        Co-Promotion Option..........................................................................      38
            4.12        Co-Promotion Committee.......................................................................      38
            4.13        Co-Branding..................................................................................      39
            4.14        Marking......................................................................................      39

5.          CONSIDERATION............................................................................................      39
            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...........................................................      40
                        5.4.3       ***..............................................................................      42
                        5.4.4       Other Product Royalties..........................................................      44
                        5.4.5       Expiration of Royalty Period.....................................................      45
                        5.4.6       Royalty Adjustments..............................................................      46
            5.5         Reports and Payments.........................................................................      46
                        5.5.1       Cumulative Royalties.............................................................      46
                        5.5.2       Royalty Statements and Payments..................................................      47
                        5.5.3       Taxes and Withholding............................................................      47
                        5.5.4       Currency.........................................................................      48
                        5.5.5       Additional Provisions Relating to Royalties......................................      48
                        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....................................................................................      50
            6.1         Inventions; Joint Patent Committee...........................................................      50
                        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............................................      62
                        6.2.4       Patent Certifications............................................................      64
                        6.2.5       Patent Term Restoration..........................................................      64
            6.3         Trademarks...................................................................................      64

7.          CONFIDENTIALITY..........................................................................................      65
            7.1         Confidentiality..............................................................................      65
            7.2         Authorized Disclosure and Use................................................................      65
                        7.2.1       Disclosure.......................................................................      65
                        7.2.2       Use..............................................................................      66
            7.3         SEC Filings..................................................................................      67
            7.4         Public Announcements; Publications...........................................................      67
                        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.........................................      69
            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...............................................................      71
            9.1         HSR Filing...................................................................................      71
            9.2         Other Government Approvals...................................................................      71
            9.3         Term.........................................................................................      71
            9.4         Termination Upon HSR Denial..................................................................      71
            9.5         Material Breach..............................................................................      72
            9.6         Termination by Wyeth.........................................................................      72
                        9.6.1       Termination Without Cause........................................................      73
                        9.6.2       Termination for a Material Safety or Regulatory Issue............................      73
            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.......................................      77
                        9.7.3       Effect of Termination by Wyeth Without Cause.....................................      80
                        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....................................      84
                        9.7.7       Post-Termination Transfer of Product Data and Filings and Existing Trademarks....      84
                        9.7.8       Manufacturing of Licensed Products After Termination.............................      85
                        9.7.9       Post-Termination Disposition of Inventories of Licensed Products.................      86
                        9.7.10      Continuation of Rights and Licenses Under Sections 6.1.1 and 6.1.2...............      86
                        9.7.11      Continuation of Other Rights and Obligations.....................................      86
            9.8         Modification of Agreement Terms by Wyeth.....................................................      86
            9.9         Survival of Certain Obligations..............................................................      87
            9.10        Change of Control............................................................................      88
                        9.10.1      Definition.......................................................................      88
                        9.10.2      Change of Control of Wyeth.......................................................      89
                        9.10.3      Change of Control of Trubion.....................................................      91

10.         INDEMNIFICATION AND INSURANCE............................................................................      91
            10.1        Indemnification by Wyeth.....................................................................      91
            10.2        Indemnification by Trubion...................................................................      91
            10.3        Procedure....................................................................................      92
            10.4        Insurance....................................................................................      93

11.         DISPUTE RESOLUTION.......................................................................................      93
            11.1        General......................................................................................      93
            11.2        Failure of Executive Officers to Resolve Dispute.............................................      93
            11.3        Disclaimer of Consequential and Punitive Damages.............................................      93

12.         MISCELLANEOUS............................................................................................      93
            12.1        Periodic Executive Meetings..................................................................      93
            12.2        Assignment...................................................................................      94
            12.3        Further Actions..............................................................................      94
            12.4        Force Majeure................................................................................      94
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            12.5        Non-Solicitation.............................................................................      94
            12.6        Correspondence and Notices...................................................................      95
                        12.6.1      Ordinary Notices.................................................................      95
                        12.6.2      Extraordinary Notices............................................................      95
            12.7        Amendment....................................................................................      96
            12.8        Waiver.......................................................................................      96
            12.9        Severability.................................................................................      96
            12.10       Descriptive Headings.........................................................................      96
            12.11       Governing Law................................................................................      97
            12.12       Entire Agreement of the Parties..............................................................      97
            12.13       Independent Contractors......................................................................      97
            12.14       Counterparts.................................................................................      97
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                                    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

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                       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.

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      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
            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 ***,
            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.

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      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.

      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.

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      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 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.

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      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.

      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

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            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 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.

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      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.

      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,

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            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.

      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

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            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:

                  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

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                  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 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

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            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.

      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

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             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.

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

      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.

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      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.

      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 ten (10)
             year 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 ten (10) year 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 ten (10) year 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,
             ***.

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      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 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.

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      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.

      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

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             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.

      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.

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      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, 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.

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             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.

                    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

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                  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 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,

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            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, 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,

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            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 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

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            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.

            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

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                   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 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

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                   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 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

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                   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:

                   (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

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                        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 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

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                        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.

                  (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.

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      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 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

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                   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 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

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                   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.

            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

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                  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 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)

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            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 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.

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      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
            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

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            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 Section 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 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

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                        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.

      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

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            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 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

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            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 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

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            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 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.

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      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.

      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.

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              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 ***                                                         ***
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

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<PAGE>

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                        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 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

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<PAGE>

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                        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 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

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<PAGE>

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                        *** 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 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

                                                                              43
<PAGE>

                                                                   REDACTED COPY

                        *** 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 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

                                                                              44
<PAGE>

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                        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 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.

                                                                              45
<PAGE>

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            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 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

                                                                              46
<PAGE>

                                                                   REDACTED COPY

                   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
                   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

                                                                              47
<PAGE>

                                                                   REDACTED COPY

                   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
                   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

                                                                              48
<PAGE>

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                   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 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

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<PAGE>

                                                                   REDACTED COPY

                   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.

            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

                                                                              50
<PAGE>

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                  (***); 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 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

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                        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 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

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                                    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 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

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                                    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 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

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                              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
                        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

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                        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
                        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

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                              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 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

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                              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 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

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                              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 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

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                        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 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

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                        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.

                  (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.

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                        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.

                  (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,

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                        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. 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

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                        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.

            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

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            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 "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

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                   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 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.

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            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.

                  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

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                        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 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

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                        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:

                  (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

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                        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
                        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

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            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) 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.

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      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 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.

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            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 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

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                              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 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:

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                  (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 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

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                              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 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;

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                        (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.

                  (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 ninety (90) days 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 to BLA filing in a Major
                              Market Country, royalties and Additional Research
                              and Development Expense Payments in

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                              amounts equal to *** of those amounts Wyeth would
                              have been obligated to pay Trubion had this
                              Agreement remained in full force and effect or
                              (II) if such termination occurs after BLA filing
                              in a Major Market Country, royalties and
                              Additional Research and Development Expense
                              Payments in amounts equal to *** of those amounts
                              Wyeth would have been obligated to pay Trubion had
                              this Agreement remained in full force and effect;
                              (C) with respect to any Licensed Products other
                              than CD20 Products ***; to pay to Wyeth royalties
                              and other non-royalty payments on commercially
                              reasonable terms; (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 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

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                              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 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

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                              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;

                        (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

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                              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

                        (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

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                              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.

           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);

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                  (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 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

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                  have no right, title or interest in or to any of the Trubion
                  Technology.

           9.7.6. POST-TERMINATION LICENSES TO WYETH TECHNOLOGY. In the event
                  that Wyeth grants to Trubion a license under any Wyeth
                  Technology pursuant to Section 9.7.1, 9.7.2, 9.7.3 or 9.7.4,
                  such license shall include, inter alia, provisions whereby
                  Trubion shall agree to comply with the applicable requirements
                  of any Third Party license to which the use or exploitation of
                  any such items may be subject including, but not limited to,
                  the payment of royalties.

           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, 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

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                  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 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

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                          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:

                  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

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                          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.  only in the event of (i) a material breach by Trubion
                          of Section 2.3.1 or 2.3.2; or (ii) a material breach
                          by Trubion of Section 8.1(e), 8.2(c) or 8.2(d); or
                          (iii) a material breach by Trubion of Section 8.2(a)
                          (and, in the case of a material breach by Trubion of
                          Section 8.2(a), only where Wyeth establishes that
                          Trubion had knowledge, as of the Signing Date, that
                          Trubion was not the sole and exclusive owner of the
                          Trubion Patent Rights or that Trubion had placed, or
                          suffered to be placed, any liens, charges or
                          encumbrances on or against the Trubion Patent Rights);
                          or (iv) if during the term of this Agreement, Trubion
                          grants to a Third Party a right or license that
                          conflicts in a material respect with Wyeth's
                          then-existing rights under this Agreement pertaining
                          to such Licensed Target(s), and thereby materially
                          breaches Trubion's obligations hereunder, then:

                        (a)   Wyeth's diligence obligations to use Commercially
                              Reasonable Efforts under Sections 4.1 and 4.10
                              shall no longer apply to Licensed Products
                              directed against such Designated Target;

                        (b)   the amount of any Additional Research and
                              Development Expense Payment that Wyeth thereafter
                              becomes obligated to pay under Section 5.3
                              relating to Licensed Products directed against
                              such Designated Target shall be reduced by fifty
                              percent (50%) of such amount; and

                        (c)   the amounts of any royalties that Wyeth thereafter
                              becomes obligated to pay under Section 5.4
                              relating to Licensed Products directed against
                              such Designated Target shall be reduced by fifty
                              percent (50%) of such amounts.

      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

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            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
                    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

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                    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 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.

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                  (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, 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

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                        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 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:

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                  (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 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

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            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 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

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            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 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);

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            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.

            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

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                   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

      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.

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      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.

      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

                                                                              97
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                                  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

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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.

      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

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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).

                                   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,

                                       3
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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.

      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

                                       4
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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, 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.

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            (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
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.

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            (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.

            (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").

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

            (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

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                  (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.

            (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.

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      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

            (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

                                       10
<PAGE>

                                                                   REDACTED COPY

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

      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

                                       11
<PAGE>
                                                                   REDACTED COPY

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.

      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>

                                                                  EXECUTION COPY

      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>

                                                                  EXECUTION COPY

                                                                       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>

                                                                   REDACTED 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>

                                                                   REDACTED COPY

                            [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>

                                                                  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.

                                           "WYETH"

                                           WYETH

                                           By: _________________________________

                                           Name: _______________________________

                                           Its: ________________________________

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

<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"

                                           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>

                                                                  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"

                               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>

                                                                  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"

                               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>

                                                                  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"

                               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>
                                                                  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"

                               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>

                                                                   REDACTED 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>

                                                                   REDACTED 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.

(iv) Without limiting the foregoing, if a specified event listed in Sections A -
C of this Exhibit 5.3 occurs with respect to a Licensed Product directed
against two or more Licensed Targets (a "Multispecific SMIP Product"), then (a)
no more than one Additional Research and Development Expense Payment shall
become payable with respect to the achievement of such event for such
Multispecific SMIP Product, (b) only the highest Additional Research and
Development Expense Payment based on the achievement of such event that has not
already become payable shall be payable, and (c) if all Additional Research and
Development Expense Payments based on the achievement of such event have already
become payable, then no payment shall be due with respect to such event for such
Multispecific SMIP Product. By way of example only, if a BLA filing and
acceptance for review in the U.S. occurs with respect to a Multispecific SMIP
Product directed against the *** and a Wyeth Target ("Wyeth Target Q"), then:
(x) if the *** Additional Research and Development Expense Payment under Section
B for such event has not already become payable, only such $15.0 million amount
shall become payable; (y) if such *** Additional Research and Development
Expense Payment had already become payable, then the *** Additional Research and
Development Expense Payment under Section C for such event shall become payable,
if it has not previously become payable; and, (z) if both such *** and such ***
Additional Research and Development Expense Payment had previously become
payable, then no payment shall be due upon BLA filing and acceptance for review
in the U.S. with respect to such Multispecific SMIP Product. To continue the
same example, if the same Multispecific SMIP Product meets the condition set
forth in (x) above, and thereafter a BLA filing and acceptance for review in the
U.S. occurs with respect to a separate Licensed Product directed only against
such Wyeth Target Q, then upon such subsequent occurrence by such separate
Licensed Product, the *** Additional Research and Development Expense Payment
shall be payable with respect to such Wyeth Target Q (if such *** payment had
not previously become payable in connection with Wyeth Target Q).

(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

                                       3
<PAGE>

                                                                   REDACTED COPY

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. ***

                                        4
<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
<PAGE>
CONFIDENTIAL

                                    APPENDIX

                                  WYETH TARGETS

<TABLE>
<CAPTION>
                                         GENBANK NUCLEOTIDE   GENBANK PROTEIN ACCESSION
  TARGET #    TARGET NAME  GENE SYMBOL    ACCESSION NUMBER             NUMBER
------------  -----------  -----------   ------------------   -------------------------
<S>           <C>          <C>           <C>                  <C>
    ***           ***          ***              ***                      ***
</TABLE><PAGE>

                                                                   EXHIBIT 10.13

                          DEVELOPMENT AND MANUFACTURING

                                SERVICE AGREEMENT

                                     BETWEEN

                               LONZA BIOLOGICS PLC

                                       AND

                          TRUBION PHARMACEUTICALS, INC.

                                                          CONFIDENTIAL TREATMENT

<PAGE>

                                TABLE OF CONTENTS

<TABLE>
<CAPTION>
                                                                                             PAGE
                                                                                             ----
<S>                                                                                          <C>
1.   Definitions.........................................................................       3

2.   Customer Obligations, Warranties and Indemnities....................................      10

3.   Provision of the Services...........................................................      12

4.   Quality; Project Management.........................................................      15

5.   Delivery, Transportation of Product and Customer Tests..............................      17

6.   Price and Terms of Payment..........................................................      19

7.   LB Warranties and Covenants and Indemnity...........................................      19

8.   Confidentiality and Non-Use.........................................................      21

9.   Termination; Ownership; License Rights..............................................      23

10.  Force Majeure.......................................................................      28

11.  Governing Law, Jurisdiction and Enforceability; Dispute Resolution..................      28

12.  Notices.............................................................................      29

13.  Miscellaneous.......................................................................      30

14.  Limitation of Liability; Exclusion of Certain Damages...............................      31
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       2
<PAGE>

      THIS AGREEMENT is made effective as of the 8th day of January 2004 (the
"Effective Date") BETWEEN

      1. LONZA BIOLOGICS PLC, the registered office of which is at 228 Bath
Road, Slough, Berkshire SL1 4DX, England (herein after referred to as "LB"), and

      2. TRUBION PHARMACEUTICALS, INC., (formerly known as GENECRAFT, INC.) of
24014th Avenue, Suite 1050, Seattle, WA 98121, USA (herein after referred to as
the "Customer").

      WHEREAS

      A. The Customer has created or controls certain Cell Lines as defined
herein; and

      B. LB has expertise in the evaluation and production of proteins for
therapeutic use using such Cell Lines; and

      C. The Customer wishes to contract LB for Services as defined herein
relating to the Cell Line as described in the Agreement; and

      D. LB is prepared to perform such Services for the Customer under the
terms and conditions set out herein.

      NOW IT IS AGREED AS FOLLOWS:

      1. DEFINITIONS. The following terms shall have the following meanings:

      "Affiliate"             means any company, partnership or other entity
                              which directly or indirectly Controls, is
                              Controlled by or is under common Control with the
                              relevant party to this Agreement. "Control" means
                              the ownership of more than fifty per cent (50%) of
                              the issued share capital or the legal power to
                              direct or cause the direction of the general
                              management and policies of the party in question.

      "Agreement"             means this agreement, including and incorporating
                              Schedule 1 (Definitions and Specifications),
                              Schedule 2 (Services), Schedule 3 (Price and Terms
                              of Payment), Schedule 4 (Quality Agreement), and
                              Schedule 5 (Commercial Terms for Technology
                              Transfer), all as the same may be amended or
                              varied from

                                                          CONFIDENTIAL TREATMENT

                                       3

<PAGE>

                              time to time by written agreement of the parties.

      "August 2003 Services   means that certain development and manufacturing
      Agreement"              agreement dated 12 August 2003 between the parties
                              for the development and manufacture of the
                              Product, as amended or varied from time to time by
                              written agreement of the parties.

      "Batch"                 means the total quantity of Manufactured Product
                              obtained from one fermentation and associated
                              purification run using the Process.

      "Cell Line"             means the cell line provided by Customer to LB,
                              the particulars of which are set out in
                              Schedule 1.

      "cGMP"                  means the regulatory requirements for current Good
                              Manufacturing Practices and General Biologics
                              Products Standards as promulgated by the United
                              States Food and Drug Administration ("FDA") (or
                              any successor agency thereto) under the United
                              States Federal Food Drug and Cosmetic Act and the
                              Public Health Service Act, at 21 CFR (Parts 210,
                              211, 600 and 610), and the Guide to Good
                              Manufacturing Practices for Medicinal Products as
                              promulgated under European Directive 91/356/EEC,
                              all as the same may be amended from time to time.

      "cGMP Product"          means Product which is required under Schedule 2
                              to be manufactured in accordance with cGMP.

      "Certificate of         means, for each Batch, a document in a format
      Analysis"               agreed to by the parties and prepared by LB
                              listing (a) the date of manufacturing, unique
                              Batch number, tests performed, Specifications,
                              test dates, and test results, (b) the quantity of
                              Manufactured Product in such Batch, and certifying
                              that such Batch was manufactured in accordance
                              with the Specifications and cGMP, and (c) the
                              tests performed by LB or permitted Testing
                              Laboratories, Specifications, and test results;
                              all with respect to such particular Batch

                                                          CONFIDENTIAL TREATMENT

                                       4
<PAGE>

                              and as required by the Specifications, the
                              accuracy of which has been certified by LB.

      "Critical Raw           has the meaning given to it in Clause 4.6 below.
      Materials"

      "Customer"              means Trubion Pharmaceuticals, Inc., and its
                              successors in title and lawful assigns.

      "Customer Information"  means (a) all Customer Know-How and other
                              tangible and intangible data, information, and
                              know-how, whether in written, printed, graphic,
                              electronic, or oral form, supplied by or on
                              behalf of Customer to LB hereunder or under the
                              August 2003 Services Agreement; (b) all
                              Documentation and all tangible and intangible
                              data, information, know-how, and Intellectual
                              Property included in the Documentation; (c) all
                              Deliverables and all tangible and intangible data,
                              information, know-how, and Intellectual Property
                              included in the Deliverables; and (d) all tangible
                              and intangible data, information, know-how, and
                              Intellectual Property included in the Customer
                              Process; "Customer Information" does not include
                              LB Know-How, the LB Patent Rights, the LB Process,
                              the New General Application Intellectual Property,
                              and LB's other Intellectual Property, "Customer
                              Information" is a part of "Customer Technology."

      "Customer Know-How"     means all know-how, technical and other
                              information relating directly or indirectly to the
                              Cell Line, the Customer Process (including for the
                              avoidance of doubt improvements or modifications
                              thereto from time to time, other than and
                              excluding the LB Process and any New General
                              Application Intellectual Property), Customer's
                              business, technology, finances or operations,
                              trade secrets, the Customer Materials, and/or the
                              Product, known by Customer from time to time;
                              "Customer Know-How" does not include LB Know-How,
                              the LB Patent Rights the LB Process, the New
                              General Application Intellectual Property, LB's
                              other Intellectual Property, and information in
                              the

                                                          CONFIDENTIAL TREATMENT

                                       5
<PAGE>

                              public domain; "Customer Know-How" is a part of
                              "Customer Information."

      "Customer Materials"    means the materials (if any) supplied by Customer
                              to LB pursuant to this Agreement.

      "Customer Patent        means all patents and patent applications,
      Rights"                 together with any extensions, reissues,
                              reexaminations, substitutions, renewals,
                              divisions, continuations, and
                              continuations-in-part thereof, of any kind
                              throughout the world that are necessary or useful
                              in performance of the Services, which from time to
                              time Customer is the owner of or entitled to use,
                              other than and excluding the LB Patent Rights.

      "Customer Process"      means that portion of the Process not composed
                              of or included within the LB Process, including
                              without limitation all processes, procedures,
                              protocols, know-how, technology, information and
                              Intellectual Property developed by LB and/or
                              Customer specifically with respect to manufacture
                              of the Product under or as a result of this
                              Agreement or the August 2003 Services Agreement;
                              "Customer Process" does not include LB Know-How,
                              the LB Patent Rights, the LB Process, the New
                              General Application Intellectual Property, or LB's
                              other Intellectual Property.

      "Customer Technology"   means all data, information, know-how, materials,
                              and Intellectual Property which from time to time
                              Customer is the owner of or entitled to use,
                              including without limitation the Customer
                              Know-How, the Customer Patent Rights, the Cell
                              Line, the Customer Materials, the Customer
                              Information, the Customer Process, the New
                              Customer Intellectual Property, and the Product;
                              "Customer Technology" does not include LB
                              Know-How, the LB Patent Rights, the LB Process,
                              the New General Application Intellectual Property,
                              LB's other Intellectual Property, and information
                              in the public domain.

                                                          CONFIDENTIAL TREATMENT

                                       6
<PAGE>

      "Deliver", "Delivered"  has the meaning given to it in Clause 5.1 below,
      or "Delivery"

      "Deliverables"          means the data, information, material, reports,
                              Documentation, Product, samples and other items
                              that LB is obligated to provide to the Customer
                              under the terms of the Services, as set forth in
                              Schedule 2.

      "Documentation"         means all data,  information  and materials,
                              whether in written, printed, graphic, or
                              electronic form, resulting from the work conducted
                              and/or results achieved in connection with the
                              Services, including without limitation documents
                              reasonably necessary for Customer to complete any
                              regulatory filings for the Product;
                              "Documentation" does not include LB Know-How, the
                              LB Patent Rights, the LB Process, the New General
                              Application Intellectual Property, and LB's other
                              Intellectual Property; "Documentation" is a part
                              of "Customer Information."

      "Intellectual Property" means proprietary methods, discoveries,
                              inventions, patents, trade secrets, copyrights,
                              trademarks, service marks, trade dress,
                              compositions, products, procedures, know-how,
                              data, reports, programs, processes, protocols,
                              written or electronic writings, illustrations,
                              images, and any other form of proprietary rights,
                              and, as the context requires, includes, among
                              other things, the Customer Know-How, the Customer
                              Patent Rights, the Customer Process, the New
                              Customer Intellectual Property, the LB Know-How,
                              the LB Patent Rights, the LB Process and the New
                              General Application Intellectual Property.

      "LB Know-How"           means all know-how, technical and other
                              information relating directly or indirectly to the
                              LB Patent Rights, the LB Process (including for
                              the avoidance of doubt improvements; or
                              modifications thereto from time to time, other
                              than and excluding the Customer Process and any
                              New Customer Intellectual Property) LB's

                                                          CONFIDENTIAL TREATMENT

                                       7
<PAGE>

                              business, technology, finances or operations, and
                              trade secrets known to LB from time to time; "LB
                              Know-How" does not include the Customer Patent
                              Rights, the Customer Know-How, the New Customer
                              Intellectual Property, the Customer Process,
                              Customer's other Intellectual Property, and
                              information in the public domain.

      "LB Patent Rights"      means all patents and  patent applications,
                              together with any extensions, reissues,
                              reexaminations, substitutions, renewals,
                              divisions, continuations, and
                              continuations-in-part thereof, of any kind
                              throughout the world relating to the LB Process
                              which from time to time LB is the owner of or is
                              entitled to use; "LB Patent Rights" does not
                              include the Customer Patent Rights and the New
                              Customer Intellectual Property and Customer's
                              other Intellectual Property.

      "LB Process"            means the manufacturing process for proteins that,
                              as of the Effective Date, is included within the
                              LB Patent Rights and LB Know-How, along with any
                              New General Application Intellectual Property, as
                              defined herein in Clause 9.8.2.

      "Legal Requirements"    means any and all laws, rules, regulations,
                              ordinances, guidelines, and standards of any
                              international, national, state, or local
                              governmental authority, applicable to LB, the
                              Services, the Product, or any facility at which
                              any of the Services are performed, including
                              without limitation (a) cGMP, and (b) all laws and
                              regulations requiring permits, licenses, filings
                              and certifications with respect to LB, the
                              Services, the Product, or any facility at which
                              any of the Services are performed.

      "Manufactured Product"  means any and all tangible forms of the Product
                              which are manufactured under this Agreement using
                              the Process, including without limitation all
                              in-process intermediates, samples and derivatives
                              thereof.

                                                          CONFIDENTIAL TREATMENT

                                       8
<PAGE>

      "New Customer
      Intellectual Property"  has the meaning given to it in Clause 9.8.3.

      "New General Application
      Intellectual Property"  has the meaning given to it in Clause 9.8.2.

      "Price"                 means the price specified in Schedule 3 for the
                              Services.

      "Process"               means the process for the production of the
                              Product from the Cell Line pursuant to this
                              Agreement, which is composed of the LB Process and
                              the Customer Process, and including any
                              improvements, changes or modifications to such
                              process from time to time.

      "Product"               means the proprietary Small Modular
                              ImmunoPharmaceutical (SMIP) known as TRU-015,
                              including any derivatives and improvements
                              thereof; and, when the context requires, the term
                              "Product" also means and refers any and all
                              tangible forms of the Product which are
                              manufactured under this Agreement using the
                              Process, including without limitation all
                              in-process intermediates, samples, derivatives,
                              and improvements thereof.

      "Quality Agreement"     means and refers to the quality agreement between
                              the parties, a copy of which is attached hereto as
                              Schedule 4, as amended or varied from time to time
                              by written agreement of the parties;

      "Run" or "run"          means a single fermentation start of the
                              manufacturing Process at LB's facility.

      "Services"              means all or any part of the services to be
                              performed by LB under this Agreement (including,
                              without limitation, cell culture evaluation,
                              purification evaluation, master, working and
                              extended cell bank creation, sample and bulk
                              production, testing of finished Product after
                              fill-finish processing of bulk Product at a third
                              party facility), as more particularly set out in
                              Schedule 2.

                                                          CONFIDENTIAL TREATMENT

                                       9
<PAGE>

      "Specialized Raw
      Materials"              has the meaning given to it in Clause 3.10 below.

      "Specifications"        means the quality, functional and analytical
                              specifications for Product, the particulars of
                              which are set out in Schedule 1.

      "Terms of Payment"      means the terms of payment specified in Schedule
                              3.

      "Testing Laboratories"  means any third party who has been instructed by
                              LB and authorized by Customer to carry out tests
                              on the Cell Line or the Product.

References to the singular number include the plural and vice versa, references
to Clauses and Schedules are references to clauses and schedules to this
Agreement.

      2. CUSTOMER OBLIGATIONS, WARRANTIES AND INDEMNITIES

            2.1 Customer shall pay the Price set out in Schedule 3 for provision
of the Services together with any additional costs and expenses mutually agreed
upon in writing by the parties that fall due under this Agreement in accordance
with the Terms of Payment.

            2.2 As agreed by the parties, the Customer shall supply to LB
certain Customer Know-How, together with full details of any hazards known to
Customer relating to the Cell Line and/or the Customer Materials, and their
storage and use. On review of this Customer Know-How by LB, the Cell Line and/or
the Customer Materials shall be provided to LB at LB's request, all as set forth
with more particularity in and in accordance with Schedule 2 (Services) hereto.
All right, title, and interest in and to the Cell Line, the Customer Materials,
the Customer Know-How and any other Customer Technology supplied to LB in
connection with this Agreement or the August 2003 Services Agreement shall, as
between the parties, remain vested in the Customer. Risk of loss to the Cell
Line, Customer Materials and any tangible Customer Information supplied to LB
under this Agreement shall transfer to LB upon delivery to LB premises.

            2.3 Subject to the terms and conditions of this Agreement, the
Customer hereby grants LB the non-exclusive, non-transferable (other than to
LB's Affiliates), right to use the Cell Line, the Customer Materials, the
Customer Know-How, and the New Customer Intellectual Property during the term of
this Agreement solely for the purpose of providing Services under this
Agreement. The Customer warrants and covenants to LB that:

                  2.4.1 Customer has the right to enter into this Agreement;

                  2.4.2 ***;

                                                          CONFIDENTIAL TREATMENT

                                       10
<PAGE>

                  2.4.3 ***;

                  2.4.4 ***;

                  2.4.5 Customer will promptly notify LB in writing if it
receives or is notified of a lawsuit that has been filed against Customer which
includes a claim from a third party that the Cell Line, other Customer
Materials, Customer Know-How, Customer Patent Rights, Customer Process, or New
Customer Intellectual Property infringes any intellectual property rights of
such third party or that the use by LB thereof for the provision of the Services
infringes any intellectual property rights of such third party; and

                  2.4.6 ***.

            2.5 Subject to Clauses 2.8 and 14 below, and subject to and except
to the extent of any indemnification from LB pursuant to Clause 7 below, the
Customer undertakes to indemnify and to maintain LB promptly indemnified against
all losses, damages, liabilities, settlements, penalties, fines, costs and
expenses of any nature (including court costs and reasonable legal fees on a
full indemnity basis), that LB may incur to the extent such liabilities arise
directly out of or result from any claim, lawsuit or other action by a third
party arising out of or resulting from any breach of any of the warranties given
by the Customer under Clause 2.4 above..

            2.6 Subject to Clauses 2.8 and 14 below, and subject to and except
to the extent of any indemnification from LB pursuant to Clause 7 below, the
Customer shall further indemnify and maintain LB promptly indemnified against
all losses, damages, liabilities, settlements, penalties, fines, costs and
expenses of any nature (including court costs and reasonable legal fees on a
full indemnity basis), that LB may incur arising out of or resulting from:

                  2.6.1 any product liability in respect of Product, unless such
liability is caused by the negligent act or omission or willful misconduct of
LB, including without limitation in the production and/or supply of Product; and

                  2.6.2 any negligent act or omission or willful misconduct of
the Customer in relation to the use, further processing, storage or sale of the
Product.

            2.7 A party that intends to claim indemnification under this
Agreement (the "Indemnitee") shall promptly notify the indemnifying party (the
"Indemnitor") in writing of any third party claim, suit or proceeding included
within the scope of the indemnification) described in Clauses 2 or 7 hereunder
(each a "Claim") with respect to which the Indemnitee intends to claim such
indemnification, and shall tender the defense of such Claim to the Indemnitor,
and the Indemnitor shall have sole control of the defense and/or settlement of
such Claim. An Indemnitee hereunder shall have the right to retain its own
counsel, subject to the following conditions: (a) the Indemnitee's counsel's
role shall be limited to monitoring the Claim and performing a watching brief of
the Claim and the Indemnitee's counsel shall have no right to actively
participate in the defense and/or settlement of such Claim; and (b) the
Indemnitor shall have the right to veto the Indemnitee's selection of counsel,
acting reasonably and having provided substantive justification

                                                          CONFIDENTIAL TREATMENT

                                       11
<PAGE>

for such veto. So long as the foregoing conditions are met, the Indemnitor shall
bear the reasonable costs and expenses of one attorney acting as the
Indemnitee's counsel in accordance with this Clause 2.7, subject to the
following additional conditions: (x) the attorney's hourly rate must be
reasonable and cannot exceed the prevailing rate, based on the venue of the
claim, suit or proceeding; and (y) the Indemnitor shall have the right to review
and approve the Indemnitee's counsel's invoices. The indemnification obligations
under this Agreement shall not apply to amounts paid in settlement of any Claim
if such settlement is effected without the consent of the Indemnitor, such
consent not to be unreasonably withheld. At the Indemnitor's request and
expense, each Indemnitee shall, and shall cause its employees to, provide full
information and reasonable assistance to Indemnitor and its legal
representatives with respect to the related Claim(s).

            2.8 Notwithstanding anything herein seemingly to the contrary,
Customer shall have no indemnity obligations under this Clause 2 for any losses,
damages, liabilities, settlements, penalties, fines, costs and expenses to the
extent such losses, damages, liabilities, settlements, penalties, fines, costs
and expenses arise out of or result from:

                  2.8.1 ***; or

                  2.8.2 ***, or

                  2.8.3 ***; or

                  2.8.4 ***.

            2.9 The provisions of this Clause 2, and the obligations of the
Customer and LB, respectively, under this Clause 2, shall survive the expiration
or termination for whatever reason of the Agreement.

            2.10 CLAUSE 2.4 IS IN LIEU OF ALL OTHER CONDITIONS, WARRANTIES AND
STATEMENTS IN RESPECT OF THE CELL LINE, CUSTOMER MATERIALS, CUSTOMER
INFORMATION, CUSTOMER KNOW-HOW, CUSTOMER PATENT RIGHTS, CUSTOMER PROCESS, NEW
CUSTOMER INTELLECTUAL PROPERTY, AND CUSTOMER TECHNOLOGY, WHETHER EXPRESSED OR
IMPLIED BY STATUTE, CUSTOM OF THE TRADE OR OTHERWISE (INCLUDING WITHOUT
LIMITATION ANY SUCH CONDITION, WARRANTY OR STATEMENT RELATING TO THE DESCRIPTION
OR QUALITY OF THE CELL LINE, CUSTOMER MATERIALS, CUSTOMER INFORMATION, CUSTOMER
KNOW-HOW, CUSTOMER PATENT RIGHTS, CUSTOMER PROCESS, NEW CUSTOMER INTELLECTUAL
PROPERTY, AND CUSTOMER TECHNOLOGY, THEIR FITNESS OR SUITABILITY FOR A PARTICULAR
PURPOSE OR USE UNDER ANY CONDITIONS WHETHER OR NOT KNOWN TO CUSTOMER) AND ANY
SUCH CONDITION, WARRANTY OR STATEMENT IS HEREBY EXCLUDED.

      3. PROVISION OF THE SERVICES

                                                          CONFIDENTIAL TREATMENT

                                       12
<PAGE>

            3.1 LB shall diligently carry out the Services as provided in
Schedule 2, and shall use all reasonable efforts consistent with levels of
effort that LB uses with its most important customers, to achieve the objectives
and estimated timescales set out in that Schedule and deliver the Product,
samples of the Product, and other Deliverables to Customer as provided in
Schedule 2; provided, however, that the timescales and Product quantities set
forth in Schedule 2 are estimates only. LB shall communicate with Customer
regularly regarding LB's performance of the Services and shall inform Customer
promptly if LB determines that LB will not or may not be able to meet the
objectives or timescales, or deliver the Product quantities, Product samples, or
other Deliverables set forth in Schedule 2.

            3.2 LB shall perform Runs and manufacture the Product in accordance
with this Agreement, and, except as expressly set forth to the contrary in
Schedule 2 or as otherwise agreed to by the parties from time to time, in
compliance with the Legal Requirements, including without limitation the
requirements of cGMP, LB warrants and covenants that, except as expressly set
forth to the contrary in Schedule 2 and in Clause 3.3 below, the Product
resulting from the Runs shall conform to the Specifications. The Product
resulting from the Runs shall be provided to Customer at no additional cost to
Customer over and above the Price, and Customer may make whatever further use of
such Product as Customer shall determine in its sole discretion, provided,
however, that, in accordance with Schedule 2, the Product manufactured in Stage
5 shall not be used in humans.

            3.3 The parties agree that the *** Batches of Product manufactured
under Stage 8 of Schedule 2 attached hereto shall comply fully with cGMP and
with the parameters and target Specifications agreed to jointly by LB and the
Customer, with an emphasis on the safety of the Product for use in human
clinical testing and with pass/fail testing for analytical methods relating to
safety. In addition, notwithstanding anything in Schedule 3 seemingly to the
contrary, with respect to the Batches of Product manufactured under Stage 8,
Customer shall ***.

                  3.3.1 ***

      If a failure to perform the Services or produce the Product for Delivery
arises due to a breach of this Agreement by LB, or LB's negligent act or
omission or willful misconduct, Customer shall be entitled to all of its rights
and remedies.

            3.4 LB shall comply with cGMP and the International Committee for
Harmonisation ("ICH") regulatory requirements, from time to time and to the
extent that the foregoing are applicable to the Services. In the event of a
conflict between the ICH regulatory requirements and the cGMP regulatory
requirements, the cGMP regulatory requirements shall prevail, except as may
otherwise be agreed by the parties in writing.

            3.5 LB hereby undertakes not to use the Cell Line, the Customer
Materials, the Customer Information, the Customer Technology, the Customer
Know-How or the Customer Patent Rights, or any part of any of the foregoing, for
any purpose other than to perform the Services and supply Product under this
Agreement. The obligations of LB under this Clause 3.6 shall survive the
expiration or termination for whatever reason of the Agreement.

                                                          CONFIDENTIAL TREATMENT

                                       13
<PAGE>

            3.6 LB shall:

                  3.6.1 at all times use best efforts to keep the Cell Line, the
Customer Materials and the Product secure and safe from loss and damage;

                  3.6.2 not part with possession of the Cell Line or the
Customer Materials or the Product, except as permitted under Clause 3.8 below
for the purpose of tests at the Testing Laboratories.

            3.7 LB shall procure that all Testing Laboratories are subject to
obligations of confidence and non-use substantially in the form of and at least
as strict as those obligations of confidence and non-use imposed on LB under
this Agreement. Each Testing Laboratory shall be subject to the prior written
approval of Customer, which approval shall not be unreasonably withheld.
Notwithstanding anything herein seemingly to the contrary, Customer shall have
the right, at Customer's option and with no penalty, to enter into an agreement
directly with one or more of the Testing Laboratories, and transfer the
associated testing services from LB under this Agreement to the Testing
Laboratory. LB shall ensure that Customer has the right to perform, directly or
through Customer's representatives, inspections and audits of all Testing
Laboratories, and Customer may condition Customer's approval of any Testing
Laboratory to Customer's performance of and satisfaction with the results of
such an inspection and audit. Customer shall perform and shall cause its
representatives to perform any such inspections and audits in compliance with
Clause 4 of this Agreement. Notwithstanding Customer's approval of any Testing
Laboratory, LB shall not disclose the contents of this Agreement (including
without limitation the Schedules hereto) or any of Customer's Confidential
Information to such approved Testing Laboratory except to the extent necessary
for such Testing Laboratory to conduct the related tests, and LB shall not
transfer possession of any of the Cell Line, Customer Materials or Product to
such approved Testing Laboratory except to the extent necessary for such Testing
Laboratory to conduct the related tests. Neither LB nor Customer shall be liable
in connection with this Agreement for any of the acts or omissions of the
Testing Laboratories. LB waives, releases and agrees not to assert against
Customer any claims for any losses, damages, liabilities, settlements,
penalties, fines, costs and expenses of any nature that LB may incur which
directly or indirectly arise out of or result from any negligent acts or
omissions or willful misconduct of the Testing Laboratories; ***. LB shall, at
Customer's expense, cooperate fully with Customer in the investigation and
prosecution of any claim, lawsuit or other proceeding by Customer against a
Testing Laboratory in connection with this Agreement for losses, damages,
liabilities, settlements, penalties, fines, costs and expenses of any nature
that Customer may incur which directly or indirectly arise out of or result from
any negligent acts or omissions or willful misconduct of the Testing
Laboratories, Nothing in this Clause shall release or shall be deemed to release
either party from any liability which arise out of or result from that party's
own negligent acts or omissions or willful misconduct. This Clause 3.8 shall
survive the expiration or termination for whatever reason of the Agreement.

            3.8 LB shall procure, maintain and store such amounts of raw
materials and components as required for the Runs, and shall perform testing and
evaluation of such materials and components as set forth in the Quality
Agreement attached hereto as Schedule 4 or agreed upon in

                                                          CONFIDENTIAL TREATMENT

                                       14
<PAGE>

writing by the parties, and the cost and expense for such materials and
components and the testing and evaluation of such materials and components shall
be deemed included in the Prices shown on Schedule 3 hereto. LB shall be
responsible for and Customer may assist with oversight and coordination of the
supply logistics for the raw materials and components required for the Runs. LB
shall not procure Specialized Raw Materials (defined below) until authorized to
do so by Customer.

            3.9 The term "Specialized Raw Materials" as used in this Agreement
means the specialized raw materials and components which are used under this
Agreement to manufacture the Product. The parties shall in good faith agree in
writing which raw materials and components shall be deemed to be "Specialized
Raw Materials" for the purposes of this Clause 3.10. In the event the cost and
expense of any Specialized Raw Materials materially exceed LB's original pricing
assumptions for such Specialized Raw Materials under this Agreement, then
Customer shall pay to LB the difference between the assumed cost and expense for
such Specialized Raw Materials and the actual cost and expense (not including
any LB mark-up or administrative fees) for such Specialized Raw Materials.

      4. QUALITY; PROJECT MANAGEMENT

            4.1 Responsibility for quality assurance and quality control shall
be allocated between the parties in accordance with the Quality Agreement, a
copy of which is attached hereto as Schedule 4, and standard operating
procedures as may be agreed upon in writing by the parties from time to time.

            4.2 Customer and its designated representatives shall have the right
to witness, inspect and audit the performance of LB's obligations, at the times
and for durations set forth in the Quality Agreement and as otherwise agreed by
the parties. Customer shall have access to the facilities, data and records of
LB which are related to this Agreement for the purpose of conducting such
inspections and audits, and LB shall use reasonable endeavours to ensure that
all Testing Laboratories provide similar access to the Testing Laboratories'
facilities, data and records which are related to this Agreement for such
purposes. In accordance with the Quality Agreement, Customer shall have the
right to review LB's non-proprietary standard operating procedures relating to
the services of LB under the Quality Agreement or this Agreement.

            4.3 In accordance with the Quality Agreement, Customer will have the
sole right to correspond with and submit regulatory applications and other
filings to the FDA, EMEA and other regulatory authorities to obtain approvals to
import, export, conduct clinical trials with, or take any other action with
respect to the Product, alone or with other products (collectively,
"Approvals"), when and as Customer may deem useful or necessary. Accordingly,
except as otherwise required by Legal Requirements, LB will not correspond
directly with the FDA, EMEA or any other regulatory agency with respect to the
Product without, in each instance, first obtaining Customer's prior written
consent. Notwithstanding the foregoing, LB will assist Customer, as requested by
Customer and at Customer's expense, in preparing, submitting, and maintaining
applications for such Approvals.

            4.4 As set forth with particularity in the Quality Agreement, LB
will permit the FDA, EMEA and other regulatory authorities to conduct
inspections of LB's facilities as the FDA,

                                                          CONFIDENTIAL TREATMENT
                                       15
<PAGE>

EMEA or other  regulatory  authorities may request,  and will cooperate with the
FDA, EMEA or other  regulatory  authorities  with respect to the inspections and
any related matters, in each case related to the Product.

            4.5 Notwithstanding anything in this Agreement seemingly to the
contrary, LB shall not undertake any modifications to the Process or testing
processes that could delay or otherwise impact the Approvals or other regulatory
submissions, including without limitation, regulatory product reviews,
Investigational New Drug applications (INDs), or any other compliance status
without in each case the prior written agreement of Customer.

            4.6 In accordance with the Quality Agreement, Customer shall have
the right (a) to review the specifications, grades and vendors of all raw
materials and components used under this Agreement to manufacture the Product,
and (b) to approve the specifications, grades and vendors of all Critical Raw
Materials (defined below), including excipients, and of all raw materials and
components of animal or human origin, all to the extent used under this
Agreement to manufacture the Product. Customer shall provide a written list to
LB of those certain raw materials and components which shall constitute and be
deemed to be "Critical Raw Materials" for purposes of this Agreement, and shall
update the list from time to time as appropriate. Each version of the written
list of the Critical Raw Materials shall be jointly agreed to by Customer and
LB. Raw materials of and components of animal or human origin shall be avoided
when possible.

            4.7 By not later than March 31, 2004, the Parties will establish a
Joint Project Team (the "JPT"). The JPT shall be composed of representatives
appointed by each of LB and the Customer. Such representatives may include, but
not be limited to, the Project Manager, Technical Lead, Manufacturing Lead,
Quality Control Lead, Quality Assurance/Regulatory Lead, Raw Materials Lead,
Supply Chain Lead and Engineering Lead, or other individuals with expertise and
responsibilities in the same areas of manufacturing, process sciences, quality
control or regulatory affairs. The JPT will meet by teleconference at least once
each week, or more frequently, as agreed by the JPT. The JPT will operate by
unanimous decision, except as expressly set forth herein. If the JPT is unable
to resolve a dispute regarding any issue presented to it, such dispute shall be
resolved in accordance with Clause 11.4. The JPT is responsible for the daily
monitoring and guidance of the Services to successfully achieve the deliverables
of the project as outlined herein.

            4.8 By not later than March 31, 2004, each Party shall appoint a
Project Manager to act as the primary contact for such Party in connection with
matters related to the performance of the Services. Each such Project Manager,
unless otherwise mutually agreed, shall serve as a member of the JPT.

            4.9 As set forth in the Quality Agreement, Customer shall have the
right to designate one of its employees or consultants as Customer's person on
plant, to be present in LB's facility during normal business hours during the
term of this Agreement to observe the Runs and observe LB's performance of its
obligations under this Agreement at times and for durations to be agreed. While
at LB's facility, Customer's representative shall comply with all of LB's
applicable policies and procedures, and, at LB's option, shall be escorted by LB
personnel.

                                                          CONFIDENTIAL TREATMENT

                                       16
<PAGE>

      5. DELIVERY, TRANSPORTATION OF PRODUCT AND CUSTOMER TESTS

            5.1 *** Unless otherwise agreed, LB shall package and label
Manufactured Product for Delivery in accordance with the Specifications and its
standard operating procedures and all applicable Legal Requirements. It shall be
the responsibility of the Customer to inform LB in writing in advance of any
special packaging and labeling requirements for Manufactured Product. All
additional costs and expenses of whatever nature incurred by LB in complying
with such special requirements shall be charged to the Customer in addition to
the Price, Transportation of Manufactured Product, whether or not under any
arrangements made by LB on behalf of Customer, shall be made at the sole risk
and expense of the Customer, provided that LB has complied with any instructions
provided by Customer with respect to transportation and insurance as set forth
in Clauses 5.2 and 5.3 below.

            5.2 If requested in writing by the Customer, LB will (acting as
agent of the Customer for such purpose) arrange the transportation of
Manufactured Product from LB's premises to the third-party fill-finish
contractor or other destination indicated by the Customer, together with
insurance coverage for Manufactured Product in transit at its invoiced value.
All additional reasonable costs and expenses of whatever nature incurred by LB
in arranging such transportation and insurance shall be charged to the Customer
in addition to the Price provided that LB has obtained Customer's prior written
consent to incurring such additional costs and expenses.

            5.3 If requested in writing by the Customer, LB will (acting as
agent for Customer) arrange for insurance of Product whilst held by LB after
Delivery (awaiting transportation). The costs and expenses of such insurance
shall be at Customer's expense and on reasonable terms equivalent to those under
which LB insures other comparable products prior to Delivery. All such
additional reasonable costs and expenses of whatever nature incurred by LB in
arranging such insurance shall be charged to the Customer in addition to the
Price, provided that LB has obtained Customer's prior written consent to
incurring such additional costs and expenses. Notwithstanding the foregoing, in
the event LB has been requested to arrange the transportation of Manufactured
Product in accordance with Clause 5.2 above, the costs and expenses of such
insurance of Manufactured Product whilst held by LB after Delivery (awaiting
transportation) shall be at LB's expense for up to fourteen (14) days and
thereafter shall be at Customer's expense, provided, however, that in the event
the delay in transportation is caused by LB, then the costs and expenses of such
insurance shall be at LB's expense until the Manufactured Product has been
loaded onto the appropriate collecting vehicle, except as may be otherwise
agreed by the parties in writing.

            5.4 LB shall deliver to Customer the Certificate of Analysis not
later than the date of Delivery. Notwithstanding the foregoing, at Customer's
request, LB will Deliver Manufactured Product in quarantine prior to delivery of
the Certificate of Analysis. Such request shall be accompanied by Customer's
written acknowledgement that the Manufactured Product has been Delivered without
the transmittal to Customer of a Certificate of Analysis, that accordingly the
Manufactured Product cannot be administered to humans until transmittal of the
Certificate of Analysis, and that Customer nevertheless accepts full risk of
loss to and title and ownership of the Manufactured Product. The Delivery of
Product in quarantine shall be subject to such testing

                                                          CONFIDENTIAL TREATMENT

                                       17
<PAGE>

requirements as LB may reasonably require, and the *** period referred to in
Clause 5.7 shall run from Customer's receipt of samples of such Manufactured
Product together with the related consolidated Batch record.

            5.5 Where LB has made arrangements for the transportation of
Manufactured Product, the Customer shall diligently examine the Manufactured
Product as soon as practicable after receipt. Notice of all claims (time being
of the essence) arising out of:

                  5.5.1 visible damage to or total or partial loss of
Manufactured Product in transit shall be given in writing to LB within *** of
receipt by Customer at Customer's facility or of receipt by Customer's third
party supplier at such third party's facility; or

                  5.5.2 non-Delivery shall be given in writing to LB within ***
after the later of (a) the date of LB's despatch notice, and (b) Customer's
actual knowledge of non-Delivery.

            5.6 The Customer shall make damaged Manufactured Product and
associated packaging materials available for inspection and shall comply with
the requirements of any insurance policy covering the Manufactured Product of
which LB has given Customer notice. LB shall offer the Customer all reasonable
assistance (at the cost and expense of the Customer) in pursuing any claims
arising out of the transportation of Manufactured Product.

            5.7 LB shall deliver to Customer samples of all Batches manufactured
under this Agreement, as and when Batches are manufactured, together with the
related consolidated Batch record requested by Customer to enable Customer to
inspect and perform testing on such samples. Promptly following receipt of
Manufactured Product or any sample thereof, the Customer may inspect the
Manufactured Product or sample and carry out any of the tests outlined or
referred to in the Specifications set out in Schedule 1 and such additional
tests as may be prudent in Customer's reasonable discretion. Subject to Clause
3.2, if such tests show that the Manufactured Product fails to meet the
Specifications, the Customer shall give LB written notice thereof within ***
after Customer's receipt at Customer's facility of samples of such Batch
together with the related consolidated Batch record and shall return such
Manufactured Product (except for reference samples retained by Customer) at LB's
expense to LB's premises for further testing. In the absence of such written
notice, Manufactured Product shall be deemed to have been accepted by the
Customer as meeting the Specifications. Subject to Clause 3.2, if Customer has
reasonably demonstrated to LB that Manufactured Product returned to LB fails to
meet the Specifications, and LB has failed to prove that such failure is due (in
whole or in part) to acts or omissions of the Customer or any third party after
Delivery, LB shall at Customer's discretion refund that part of the Price that
relates to the production of such Manufactured Product or replace such
Manufactured Product at LB's own cost and expense. In the event Customer
requires LB to replace such Manufactured Product, LB shall use all reasonable
endeavours to do so as soon as possible with the minimum delay.

            5.8 Subject to Clause 3.2, if there is any dispute concerning
whether Manufactured Product returned to LB fails to meet the Specifications or
whether such failure is due (in whole or in part) to acts or omissions of the
Customer or any third party after Delivery, such

                                                          CONFIDENTIAL TREATMENT

                                       18
<PAGE>

dispute shall be resolved in accordance with the dispute resolution procedures
described in Clause 11.4 below.

            5.9 Subject to Clause 7, LB's liability hereunder in respect of
Manufactured Product that fails to meet the Specifications shall be limited to
refund or replacement, in accordance with and as set forth with more
particularity in Clause 5,7 above; provided, however, that the foregoing
limitation of liability shall not apply in the event such failure is caused by
the negligent act or omission or willful misconduct of LB.

      6. PRICE AND TERMS OF PAYMENT

            6.1 Unless otherwise indicated in writing by LB, all prices and
charges payable to Lonza are exclusive of Value Added Tax or of any other
applicable taxes, levies, imposts, duties and fees of whatever nature imposed by
or under the authority of any government or public authority, which shall be
paid by the Customer (other than taxes on LB's income). LB shall add all such
taxes as separate line items on invoices. All invoices are strictly net and
payment must be made within thirty (30) days of Customer's receipt of invoice.
Notwithstanding the foregoing, no amounts shall be invoiced until such amounts
are then due and payable in accordance with the Schedules to this Agreement,
including without limitation and as appropriate the completion of the related
Services and Customer's receipt and acceptance of the related Deliverables. The
invoices shall be in ***, and all payments made by Customer shall be made in
***.

            6.2 In default of payment on due date:

                  6.2.1 interest shall accrue on any amount overdue at the per
annum interest rate *** above *** from time to time as published in the "Money
Rates" section of The Wall Street Journal, on the 1st business day of each
month, beginning with the month in which the payment became delinquent, with
interest to accrue on a day to day basis both before and after judgement, adjust
monthly on the 1st day of each month, beginning with the second month of
delinquency, and be calculated on the number of days such payment is delinquent;
and

                  6.2.2 For so long as such payment delinquency remains uncured,
LB shall, at its sole discretion, and without prejudice to any other of its
accrued rights, be entitled to suspend the provision of the Services or, if
Customer has not remedied such payment delinquency within *** of the receipt by
Customer of notice of nonpayment and demand for remedy, to treat the Agreement
as repudiated.

      7. LB WARRANTIES AND COVENANTS AND INDEMNITY

            7.1 LB warrants and covenants that:

                  7.1.1 the Services shall be performed in accordance with this
Agreement, including without limitation Clauses 3.1 and 3.2 above;

                                                          CONFIDENTIAL TREATMENT

                                       19
<PAGE>

                  7.1.2 LB has the right and necessary corporate authorisations
to enter into this Agreement;

                  7.1.3 LB has the necessary rights to licence or permit
Customer to use the LB Process, LB Know-How, LB Patent Rights, and New General
Application Intellectual Property in accordance with the terms of this
Agreement, including without limitation in accordance with and pursuant to
Clause 9 below;

                  7.1.4 any of the LB Process, LB Know-How, LB Patent Rights,
and New General Application Intellectual Property referred to in Clause 7.1.3
above that are not owned by LB are licensed to LB under a licence which grants
LB the necessary rights to licence or permit Customer to use the LB Process, LB
Know-How, LB Patent Rights, and New General Application Intellectual Property in
accordance with the terms of this Agreement, including without limitation in
accordance with and pursuant to Clause 9 below;

                  7.1.5 LB will not cause or permit any liens or encumbrances of
any kind arising through LB to attach to Product, and unencumbered title to
Manufactured Product will be conveyed to Customer upon Delivery;

                  7.1.6 the LB Know How, LB Patent Rights, LB Process and the
New General Application Intellectual Property are owned by LB or LB is otherwise
entitled to use them for the purposes of providing Services under this Agreement
and LB shall not do or cause anything to be done which would adversely affect
their ownership or entitlement to use the same for those purposes;

                  7.1.7 to the best of LB's knowledge and belief, the use of the
LB Process, LB Know-How, LB Patent Rights, and New General Application
Intellectual Property in accordance with the terms of this Agreement (including
without limitation the use by Customer in accordance with and pursuant to the
provisions of Clause 9 below) do not and will not infringe any intellectual
property rights or industrial property rights of any third party (including
without limitation any LB Affiliate) and do not involve the wrongful use of any
trade secret or confidential information, nor is there any claim to the contrary
outstanding;

                  7.1.8 LB will notify Customer in writing immediately if it
receives or is notified of a claim that the use by LB of the LB Process, LB
Know-How, LB Patent Rights and/or New General Application Intellectual Property
for Services or the use by Customer in accordance with the terms of this
Agreement infringes any third party's intellectual property rights or industrial
property rights or involves the wrongful use of any trade secret or confidential
information; and

                  7.1.9 at the date of this Agreement LB is not a party to any
agreement that prohibits or prevents it from performing the Services or
otherwise fulfilling its obligations under this Agreement and covenants that it
will not enter into any such agreement.

            7.2 CLAUSES 3, 4 AND 7.1 ARE IN LIEU OF ALL CONDITIONS, WARRANTIES
AND STATEMENTS IN RESPECT OF THE SERVICES AND/OR THE

                                                          CONFIDENTIAL TREATMENT

                                       20
<PAGE>

PRODUCT WHETHER EXPRESSED OR IMPLIED BY STATUTE, CUSTOM OF THE TRADE OR
OTHERWISE (INCLUDING BUT WITHOUT LIMITATION ANY SUCH CONDITION, WARRANTY OR
STATEMENT RELATING TO THE DESCRIPTION OR QUALITY OF THE PRODUCT, ITS FITNESS OR
SUITABILITY FOR A PARTICULAR PURPOSE OR USE UNDER ANY CONDITIONS WHETHER OR NOT
KNOWN TO LB) AND ANY SUCH CONDITION, WARRANTY OR STATEMENT IS HEREBY EXCLUDED.

            7.3 Subject to and except to the extent of any indemnification from
Customer pursuant to Clauses 2.5 and 2.6 above, LB undertakes to indemnify and
to maintain Customer promptly indemnified against all losses, damages,
liabilities, settlements, penalties, fines, costs and expenses of any nature
(including court costs and reasonable legal fees on a full indemnity basis),
that Customer may incur to the extent such liabilities arise directly out of or
result from any claim, lawsuit or other action by a third party arising out of
or resulting from (a) any breach of any of the warranties given by LB in Clause
7.1 above; or (b) any negligent act or omission or willful misconduct of LB.

            7.4 Notwithstanding anything herein seemingly to the contrary, LB
shall have no indemnity obligations under this Clause 7 for any losses, damages,
liabilities, settlements, penalties, fines, costs or expenses to the extent such
losses, damages, liabilities, settlements, penalties, fines, costs and expenses
arise out of or result from: ***

            7.5 Nothing contained in this Agreement shall purport to exclude or
restrict any liability for death or personal injury resulting directly from
negligence by LB in carrying out the Services or any liability for breach of the
implied undertakings of LB as to title.

            7.6 This Clause 7 and the obligations of LB under this Clause 7
shall survive the expiration or termination for whatever reason of the
Agreement.

      8. CONFIDENTIALITY AND NON-USE

            8.1 The Customer acknowledges that LB Know-How, LB Process, LB
Patent Rights and General Application Intellectual Property and any of LB's
other Intellectual Properly disclosed to, supplied to or held by Customer
pursuant to this Agreement, and LB acknowledges that Customer Know-How, Customer
Patent Rights, Customer Technology, Customer Information, Customer Process, New
Customer Intellectual Property, Customer Materials and the Cell Line and any of
Customer's other Intellectual Property disclosed to, supplied to or held by LB
pursuant to this Agreement (all of the foregoing collectively referred to as
"Confidential Information") is, subject to Clause 8.5, supplied and shall be
held in circumstances imparting an obligation of confidence and each agrees to
keep the other party's Confidential Information secret and confidential and to
respect the other's proprietary rights therein and not at any time for any
reason whatsoever to disclose or permit such Confidential Information to be
disclosed to any third party save as expressly provided herein or to be used for
any purpose not expressly authorized under this Agreement For the avoidance of
doubt, the parties agree that all portions of documents and records describing
and to the extent relating to the Product and the Customer Process shall be kept
confidential by Lonza in accordance with the terms of this Clause 8.

                                                          CONFIDENTIAL TREATMENT

                                       21
<PAGE>

            8.2 The Customer and LB shall each procure that all their respective
employees, consultants, contractors and persons for whom it is responsible
having access to the other party's Confidential Information shall be subject to
the same obligations of confidence as the principals pursuant to Clauses 8.1 and
8.3 and, in addition, with respect to LB, to the same obligations of non-use
pursuant to Clauses 2.3, 3.6 and 8.1, and shall be bound, by written
confidentiality agreements in support of all such obligations.

            8.3 LB and the Customer each undertake, except as set forth herein,
not to disclose or permit to be disclosed to any third party, or otherwise make
use of or permit to be made use of (a) any Confidential Information of the
other, or of any Affiliate of the other, or of any suppliers, agents,
distributors, licensees or other customers of the other which comes into the
receiving party's possession under this Agreement or (b) the commercial terms of
this Agreement, except to the extent that any of the foregoing is required to be
disclosed pursuant to subpoena, court order, judicial process or otherwise by
law, provided the receiving party provides prompt notice to the disclosing party
of such requirement in order to give the disclosing party an opportunity to
timely seek a protective order or other appropriate judicial relief. In the
event the disclosing party is unable to obtain a protective order or other
appropriate judicial relief, the receiving party shall disclose only that
portion of the disclosing party's Confidential Information which is legally
required to be disclosed, and ensure that all such Confidential Information of
the disclosing party shall be redacted to the fullest extent permitted by law
prior to such disclosure and that the disclosing party shall be given an
opportunity to review the Confidential Information prior to its disclosure.
Notwithstanding the foregoing, (i) LB may disclose Customer's Confidential
Information to LB's Affiliate, Lonza Biologics, Inc., for purposes consistent
with this Agreement; provided, however, that LB shall ensure that its Affiliate
is subject to obligations of confidentiality and non-use with respect to the
Confidential Information at least as strict as those set forth herein, and
provided further that LB shall remain liable for the acts or omissions of its
Affiliate with respect to such Confidential Information, and (ii) either party
may disclose the other party's Confidential Information to any contractors or
consultants approved in writing by the other party, such approval not to be
unreasonably withheld or delayed, for purposes consistent with this Agreement;
provided, however, that in each case the party disclosing the other party's
Confidential Information shall ensure that the third party receiving the
information is subject to contractual obligations of confidentiality and non-use
with respect to the Confidential Information at least as strict as those set
forth herein; and provided further that the party disclosing the other party's
Confidential Information shall remain liable for the acts or omissions of such
third party with respect to such Confidential Information.

            8.4 The obligations of confidence referred to in this Clause 8 shall
not extend to any information which:

                  8.4.1 is or becomes generally available to the public
otherwise than by reason of a breach by the recipient party of the provisions of
this Clause 8;

                  8.4.2 is known to the recipient party and is at its free
disposal, without an obligation of confidence, prior to its receipt from the
disclosing party;

                                                          CONFIDENTIAL TREATMENT

                                       22
<PAGE>

                  8.4.3 is subsequently disclosed to the recipient party without
being made subject to an obligation of confidence; or

                  8.4.4 is developed by any servant or agent of the recipient
party without access to or use or knowledge of the Confidential Information of
the disclosing party.

            8.5 The parties acknowledge that:

                  8.5.1 without prejudice to any other rights and remedies that
the parties may have, the parties agree that the Confidential Information is
valuable and that damages may not be an adequate remedy for any breach of the
provisions of Clauses 2.3, 3.6, 8.1, 8.2, 8.3 and 8.4. The parties agree that
the relevant party will be entitled without proof of special damage to the
remedies of an injunction and other equitable relief for any actual or
threatened breach by the other party;

                  8.5.2 Customer acknowledges that, save as expressly provided
in this Agreement (including without limitation Clauses 9.8.4 and 9.8.7 below),
the Customer shall not at any time have any right, title, license or interest in
or to LB Know-How, the LB Patent Rights, the LB Process, the New General
Application Intellectual Property or any of LB's other Intellectual Property,
and

                  8.5.3 LB acknowledges that, save as expressly provided in this
Agreement, LB shall not at any time have any right, title, license or interest
in or to the Customer Information, the Customer Materials, the Cell Line,
Customer Know-How, Customer Patent Rights, the Customer Technology, the New
Customer Intellectual Property, the Customer Process or any of Customer's other
Intellectual Property.

            8.6 This Clause 8 and the obligations of LB and the Customer under
this Clause 8 shall survive the expiration or termination for whatever reason of
the Agreement.

      9. TERMINATION; OWNERSHIP; LICENSE RIGHTS

            9.1 This Agreement shall begin on the Effective Date and, unless
earlier terminated as set forth in this Clause 9, shall terminate and expire
when the last obligation to be performed under this Agreement has been
performed. If it becomes apparent to either LB or the Customer at any stage in
the provision of the Services that it will not be possible to complete the
Services for scientific or technical reasons, and such party gives written
notice thereof to the other party, a sixty (60) day period shall be allowed for
good faith discussion and attempts to resolve such problems. If such problems
are not resolved within such period, LB and the Customer shall each have the
right to terminate the Agreement forthwith by notice in writing. In the event of
such termination, the Customer shall pay to LB a termination sum calculated by
reference to all the Services performed by LB prior to such termination
(including a pro rata proportion of the Price for any stage of the Services
which is in process at the date of termination) and all expenses reasonably
incurred by LB in giving effect to such termination, including the costs of
terminating any commitments entered into under the Agreement, such termination
sum not to exceed the Price.

                                                          CONFIDENTIAL TREATMENT

                                       23
<PAGE>

            9.2 Customer may in its sole discretion terminate the Services at
any time for any reason or for no reason whatsoever by giving not less than ***
notice in writing to LB. In the event of termination pursuant to this Clause 9.2
and subject to Clauses 9.4 and 9.5, the Customer shall pay LB a termination sum
calculated in accordance with the principles of Clause 9.1 above plus;

                  9.2.1 in the event notice to terminate Services pursuant to
this Clause 9.2 is issued to LB six (6) months or less before LB's then
estimated start date for any stage of those Services which include cGMP
fermentation activities, Customer shall pay LB a sum equal to the full Price of
that stage or those stages in question, which payment shall fall due to LB on or
before the date of termination of such Services; or

                  9.2.2 in the event notice to terminate Services pursuant to
this Clause 9.2 is issued to LB more than six (6) but not more than twelve (12)
months before LB's then estimated start date for any stage of those Services
which include cGMP fermentation activities, Customer shall pay LB a sum equal to
eight-five percent (85%) of the full Price of that stage or those stages in
question, which payment shall fall due to LB on or before the date of
termination of such Services; or

                  9.2.3 in the event notice to terminate Services pursuant to
this Clause 9.2 is issued to LB more than *** before LB's then estimated start
date for any stage of Services which include cGMP fermentation activities, no
payment shall be due for the stage or stages in question.

            9.3 The obligation to make payment under Clause 9.2 shall be reduced
(retrospectively, and hence LB shall make an appropriate refund to Customer) to
the extent that LB mitigates its loss in this regard (and LB shall promptly
notify the Customer of any such mitigation). LB shall make all reasonable
efforts so to mitigate such losses. This provision shall not entitle the
Customer to be refunded an amount greater than that paid by Customer to LB
pursuant to this Clause 9 ***.

            9.4 For the avoidance of doubt, activities relating to cGMP
fermentation shall be deemed to commence with the date of removal of the vial of
cells for the performance of the fermentation from frozen storage.

            9.5 In addition to the termination rights set forth above, the
parties may each terminate the Agreement forthwith by notice in writing to the
other party upon the occurrence of any of the following events:

                  9.5.1 if one party commits a material breach of the Agreement
(which shall include without limitation a breach of the warranties set out in
Clauses 2 and 7 respectively), and such breach is not capable of remedy, then
the non-breaching party may terminate the Agreement forthwith by notice in
writing to the breaching party, and, if such breach is capable of remedy but is
not remedied within *** of the receipt by the breaching party of notice
identifying the breach and requiring its remedy, then the non-breaching party
may terminate the Agreement forthwith by notice in writing to the breaching
party; or

                                                          CONFIDENTIAL TREATMENT

                                       24
<PAGE>

                  9.5.2 if one party ceases for any reason to carry on business
or compounds with or convenes a meeting of its creditors or has a receiver or
manager appointed in respect of all or any part of its assets or is the subject
of an application for an administration order or of any proposal for a voluntary
arrangement or enters into liquidation (whether compulsorily or voluntarily) or
undergoes any analogous act or proceedings under foreign law, then the other
party may terminate the Agreement forthwith by notice in writing to the
breaching party.

            9.6 Upon the termination or expiration of the Agreement for whatever
reason:

                  9.6.1 LB shall cease all use of and shall promptly return to
the Customer all Customer Information and shall, as directed by Customer,
dispose of or return to the Customer the Customer Materials, the Cell Line, the
Product, the Deliverables, the Documentation, any in-process Product or
materials, and any materials deriving from any of the foregoing. Notwithstanding
the foregoing, the parties agree that, in the event LB has terminated the
Agreement pursuant to Clause 9.5.1 above because of a material payment default
by Trubion, men LB shall have no obligation to deliver Manufactured Product (or
Product to the extent the term "Product" refers to the tangible forms of the
Product manufactured under this Agreement using the Process) to Trubion as
required under this Clause 9.6.1 unless and until the payment default has been
cured;

                  9.6.2 LB shall not thereafter use or exploit the Customer
Know-How, Customer Patent Rights, the Customer Technology, the New Customer
Intellectual Property (including without limitation the Customer Process), the
Customer Information, the Cell Line, the Product, or the Customer Materials, or
any of Customer's other Intellectual Property;

                  9.6.3 the Customer shall promptly return to LB all LB Know-How
it has received from LB;

                  9.6.4 the Customer shall not thereafter use or exploit the LB
Patent Rights the LB Process or the LB Know-How or any of LB's other
Intellectual Property in any way whatsoever, except as permitted under and in
accordance with Clauses 9.8.4, 9.8.7, and 9.9 below and subject to the
provisions set forth in Clause 9.10 below;

                  9.6.5 LB shall refund within thirty (30) days of the effective
date of such termination all amounts paid to LB in excess of the amounts owed to
LB under this Agreement, including without limitation the amounts owed to LB if
any, pursuant to this Clause 9; and

                  9.6.6 LB and the Customer shall do all such acts and things
and shall sign and execute all such deeds and documents as the other may
reasonably require to evidence compliance with this Clause 9.6.

            9.7 Expiration or termination of the Agreement for whatever reason
shall not affect the accrued rights of either LB or the Customer arising under
or out of this Agreement and all provisions which are expressed to survive the
Agreement shall remain in full force and effect. For the avoidance of doubt, the
provisions of Clauses 2, 3, 7, 8, 9, 11 and 14 will survive the expiration or
termination of this Agreement for any reason, and, except as otherwise expressly
provided in this

                                                          CONFIDENTIAL TREATMENT

                                       25
<PAGE>

Clause 9.7, all other rights and obligations of the parties under this Agreement
will terminate upon termination or expiration of this Agreement.

            9.8 Ownership; License Rights.

                  9.8.1 Except as expressly provided in Clause 2.3 above and
Clause 9.8.7 below, neither party will, as a result of this Agreement, acquire
any right, title, or interest in any Intellectual Property that the other party
owned or controlled as of the Effective Date of this Agreement, or that the
other party obtains ownership or control of separate and apart from the
performance of this Agreement.

                  9.8.2 Except as expressly provided in Clause 9.8.4 below, LB
shall own all right, title and interest in "New General Application Intellectual
Property." which as used in this Agreement means Intellectual Property that LB
and/or its Affiliates, contractors or agents develops, conceives, invents,
reduces to practice or makes in the course of performance of this Agreement and
that meets each of the following three criteria: ***.

                  9.8.3 Except for and not including the New General Application
Intellectual Property, Customer shall own all right, title, and interest in any
and all Intellectual Property that LB and/or its Affiliates, the Testing
Laboratories or other contractors or agents of LB conceives, invents, reduces to
practice, develops or makes, solely or jointly with Customer or others, in the
course of performance of this Agreement or as a result of receipt of Customer
Technology (collectively, the "New Customer Intellectual Property"), including
without limitation the Customer Process and all improvements to the Customer
Technology. For the avoidance of doubt, the parties confirm that LB shall have
no obligation to cause any of the Testing Laboratories or other contractors or
agents of LB to assign their respective rights, titles and interests in any New
Customer Intellectual Property to Trubion, other than the obligations set forth
in Clause 9.8.5 below. LB hereby assigns to Customer and shall continue to
assign to Customer all of its right, title and interest in any New Customer
Intellectual Property. LB shall promptly disclose to Customer in writing all New
Customer Intellectual Property. LB shall execute, and shall require LB's
personnel involved in the performance of the Services to execute, any documents
required to confirm Customer's ownership of the New Customer Intellectual
Property, and any documents required to apply for, maintain and enforce any
patents or other rights in the New Customer Intellectual Property. Upon
Customer's request and at Customer's reasonable expense, and at no cost to LB,
LB shall assist Customer as may he necessary to apply for, maintain and enforce
any patents or other rights in the New Customer Intellectual Property. For the
avoidance of doubt, the parties agree that the term "New Customer Intellectual
Property" shall not under any circumstances be interpreted or defined to include
any "New General Application Intellectual Property."

                  9.8.4 Subject to Clause 9.10 below, LB hereby grants Customer
a non-exclusive, worldwide, fully paid-up, irrevocable and transferable license,
with the right to grant and authorize sublicenses, under and to all New General
Application Intellectual Property, to the extent such New General Application
Intellectual Property is useful or beneficial to develop, conduct

                                                          CONFIDENTIAL TREATMENT

                                       26
<PAGE>

clinical trials for, formulate, manufacture, test, seek regulatory approval for,
market, commercialize, make, have made, use, sell, import, and distribute
Product.

                  9.8.5 LB shall use its reasonable efforts to procure that all
Testing Laboratories and other contractors arid agents of LB involved in the
performance of the Services, and their respective personnel, shall be subject to
the same agreements and obligations as LB pursuant to Clauses 9.8.3 and 9.8.4,
and shall be bound by written agreements in support of all such agreements and
obligations, including without limitation an assignment to Customer all of the
Testing Laboratories, contractors and agents' right, title and interest in any
New Customer Intellectual Property.

                  9.8.6 Upon the earlier of the completion of the Services or
the termination or expiration of this Agreement, LB shall deliver to Customer
all materials related to the New Customer Intellectual Property, regardless of
the method of storage or retrieval, in such form as such materials are then
currently in the possession of LB. Alternatively, at Customer's written request,
LB shall dispose of such related materials or retain them for a period of time
agreed upon by the parties; provided, however, that Customer shall pay the
reasonable costs associated with LB disposing of or retaining such materials.

                  9.8.7 Subject to Clause 9.10 below, LB hereby grants Customer
a non-exclusive, worldwide, fully paid-up, irrevocable and transferable license,
with the right to grant and authorize sublicenses, under and to the LB Patent
Rights and LB Know-How to use the LB Patent Rights, the LB Know-How and the LB
Process, alone or in combination with the Customer Process or such other
technology or Intellectual Property that Customer chooses, in its sole
discretion, to develop, conduct clinical trials for, formulate, manufacture,
test, seek regulatory approval for, market, commercialize, make, have made, use,
sell, import, and distribute Product. For the avoidance of doubt, no licence is
granted to Customer under this Clause 9.8.7 or otherwise under this Agreement in
respect of LB's glutamine synthetase (GS) gene expression system, which shall be
the subject of a separate licence agreement between the parties.

            9.9 The parties intend that the Process shall be fully portable by
Trubion. The parties intend that the Process shall be fully portable by Trubion.
At the request of Customer at any time and from time to time during the term of
this Agreement and within *** following the expiration or termination of this
Agreement, LB shall transfer to Customer (or its designee) the Process for the
Product and all manufacturing technology and know-how related thereto (the
"Technology Transfer"). ***.

            9.10 Notwithstanding anything in Clause 9.8.4 or 9.8.7 seemingly to
the contrary, the parties agree as follows:

                  9.10.1 Upon the expiration or termination of this Agreement,
Customer shall have no right to exercise the license rights granted by LB to
Customer under Clauses 9.8.4 and 9.8.7 unless and until the Technology Transfer
fee has been paid in accordance with Clause 9.9 above.

                                                          CONFIDENTIAL TREATMENT

                                       27
<PAGE>

                  9.10.2 During the term of this Agreement, Customer shall have
no right to exercise the license rights granted by LB to Customer under Clauses
9.8.4 and 9.8.7 to manufacture the Product at a Trubion facility or at a
third-party facility that is not owned or operated by Lonza or its Affiliates,
unless and until the Technology Transfer fee described in Clause 9.9 above has
been paid.

Furthermore, for the avoidance of doubt, the parties agree that the Technology
Transfer shall be performed in accordance with and subject to the provisions of
Clause 9.9, and the parties acknowledge that Clause 9.9, and the obligations of
the parties thereunder, shall survive the expiration or termination of this
Agreement.

            9.11 The terms of this Clause 9 shall survive the expiration or
termination for whatever reason of this Agreement.

      10. FORCE MAJEURE

            10.1 If either party is prevented or delayed in the performance of
any of its obligations under the Agreement by Force Majeure and shall give
written notice thereof to the other party specifying the matters constituting
Force Majeure together with such evidence as the party giving notice reasonably
can give and specifying the period for which it is estimated that such
prevention or delay will continue, the party giving notice shall be excused from
the performance or the punctual performance of such obligations as the case may
be from the date of such notice for so long as such cause of prevention or delay
shall continue. Notwithstanding the foregoing, in the event that LB is prevented
from performance by Force Majeure by longer than ***, Customer shall be entitled
to terminate this Agreement upon written notice, but such termination shall not
be considered as termination under Clause 9.5.1 hereof.

            10.2 The expression "Force Majeure" shall be deemed to include any
cause affecting the performance by a party of the Agreement to the extent that
it arises from or attributable to acts, events, acts of God, omissions or
accidents beyond the reasonable control of the party giving notice of the Force
Majeure event.

      11. GOVERNING LAW, JURISDICTION AND ENFORCEABILITY; DISPUTE RESOLUTION

            11.1 The construction, validity and performance of the Agreement
shall be governed by the laws of ***. This Agreement shall not be governed by
the United Nations Convention on Contracts for the International Sale of Goods,
the application of which is disclaimed.

            11.2 No failure or delay on the part of either LB or the Customer to
exercise or enforce any rights conferred on it by the Agreement shall be
construed or operate as a waiver thereof nor shall any single or partial
exercise of any right, power or privilege or further exercise thereof operate so
as to bar the exercise or enforcement thereof at any time or times thereafter.

                                                          CONFIDENTIAL TREATMENT

                                       28
<PAGE>

            11.3 The illegality or invalidity of any provision (or any part
thereof) of this Agreement shall not affect the legality, validity or
enforceability of the remainder of its provisions or the other parts of such
provision as the ease may be.

            11.4 If any dispute arises relating to the performance of either
party under this Agreement that the parties are unable to resolve in the
ordinary course of business (a "Dispute"), the parties will use good-faith
efforts to resolve the matter in accordance with this Clause 11.4 prior to
instituting any legal proceeding in connection therewith; provided, however,
that nothing herein will require either party to forego or delay the institution
of any proceeding to seek equitable or injunctive relief to stop or prevent any
breach of this Agreement if it reasonably believes that it would be irreparably
harmed by any delay in seeking such relief. If a dispute occurs, either party
may, by written notice to the other party, have such dispute referred to their
respective officers designated below (or their respective designees) for
attempted resolution by good faith negotiations within *** after such notice is
received. The original designated officers are:

      For LB: Rene Imwinkelried, Director and Head of Slough Site

      For Customer: Dr. Peter A. Thompson, MD, President and CEO.

      In the event the designated officers (or their respective designees) are
not able to resolve such dispute within such ***, or such other period of time
as the parties may mutually agree in writing, the parties shall have the right
to pursue any and all remedies at law and in equity. Notwithstanding the
foregoing, Disputes regarding nonconforming bulk Product under Section 5.9 above
will be referred first to the officers designated above and then, in the event
that such officers are unable to resolve the Dispute, to an independent expert
(acting as an expert and not as an arbitrator) to be appointed by agreement
between LB and the Customer or, in the absence of agreement, by the President
for the time being of the Association of the British Pharmaceutical Industry.
The costs of such independent expert shall be borne equally between LB and the
Customer. The decision of such independent expert shall be in writing and, save
for manifest error on the face of the decision, shall be binding on both LB and
the Customer.

      12. NOTICES

            12.1 Any notice or other communication to be given under this
Agreement shall be delivered personally or sent by facsimile transmission and
acknowledged by the intended recipient, or if facsimile transmission is not
available, by first class pre-paid post addressed as follows:

            If to Lonza Biologics to:       Lonza Biologics plc
                                            228 Bath Road
                                            Slough
                                            Berkshire SL1 4DX
                                            England
                                            Facsimile: +44 1753 777001

            For the attention of:           ***

                                                          CONFIDENTIAL TREATMENT

                                       29
<PAGE>

            If to the Customer to:          Trubion Pharmaceuticals, Inc.
                                            24014th Ave., Suite 1050
                                            Seattle, WA 98121
                                            USA
                                            Facsimile: +1-206-838-0503

            For the attention of:           Kendall M. Mohler, Ph.D.
                                            Senior Vice President, R & D

or to such other destination as either party hereto may hereafter notify to the
other in accordance with the provisions of this Clause 12.

            12.2 All such notices or other communications shall be deemed to
have been served as follows:

                  12.2.1 if delivered personally, at the time of such delivery;

                  12.2.2 if sent by facsimile, upon receipt of the transmission
confirmation slip showing completion of the transmission;

                  12.2.3 if sent by first class pre-paid post, upon receipt by
the addressee.

      13. MISCELLANEOUS

            13.1 Neither party shall be entitled to assign, transfer, charge or
in any way make over the benefit and/or the burden of this Agreement without the
prior written consent of the other which consent shall not be unreasonably
withheld or delayed, save that either party shall be entitled without the prior
written consent of the other to assign, transfer, charge, sub-contract, deal
with or in any other manner make over the benefit and/or burden of this
Agreement to an Affiliate or to any company with which the assigning party may
merge or to any company to which it may transfer its assets and undertakings.

            13.2 The text of any press release or other communication to be
published by or in the media concerning the subject matter of the Agreement
shall require the prior written approval of LB and the Customer, LB shall not
make use of Customer's name in any advertisement or promotional material or
customer list without in each case the prior written consent of Customer.
Consent to be given under this Clause 13.2 shall not be unreasonably withheld or
delayed. Notwithstanding anything in this Agreement seemingly to the contrary,
LB hereby consents to Customer's disclosure of LB's name to Customer's current
and potential employees, directors, shareholders, investors, partners, and
subcontractors.

            13.3 The Agreement embodies the entire understanding of LB and the
Customer and there are no promises, terms, conditions or obligations, oral or
written, expressed on implied, other than those contained in the Agreement, The
terms of the Agreement shall supersede all

                                                          CONFIDENTIAL TREATMENT

                                       30
<PAGE>

previous agreements (if any) which may exist or have existed between LB and the
Customer relating to the Services.

            13.4 The parties to this Agreement do not intend that any term
hereof should be enforceable by virtue of the Contracts (Rights of Third
Parties) Act 1999 by any person who is not a party to this Agreement.

            13.5 No variation of or addition to this Agreement or any part
thereof shall be effective unless in writing and signed on behalf of both
parties, Notwithstanding the above the parties hereby confirm that amendments to
the Specifications shall be effective if reduced to writing and signed by the
quality and/or regulatory representative of both parties, which quality and/or
regulatory representative shall be nominated from time to time by each party. In
the event of any conflict between the main body of this Agreement and any
Schedule, the terms of the main body of this Agreement shall control.

            13.6 Each of the parties to this Agreement is an independent
contractor and nothing herein contained shall be deemed to constitute the
relationship of partners, joint venturers, nor of principal and agent between
the parties. Neither party shall hold itself out to third parties as purporting
to act on behalf of, or serving as the agent of, the other party.

            13.7 This Agreement and any amendment hereto may be executed in any
number of counterparts, each of which shall be deemed an original and all of
which shall constitute the same instrument This Agreement may be executed by
facsimile or original, and a facsimile signature shall be deemed to be and shall
be as effective as an original signature.

      14. LIMITATION OF LIABILITY; EXCLUSION OF CERTAIN DAMAGES

            14.1 LB's aggregate liability for direct damages arising out of or
in connection with this Agreement or the transactions contemplated hereby shall
not exceed the total maximum aggregate sum payable under this Agreement for the
Services, in accordance with Schedule 3 (Price and Terms of Payment) attached
hereto, except that the foregoing limitation shall not apply in the case of (a)
breach of Clause 8 (Confidentiality and Non-Use) by LB, (b) personal injury or
death, or (c) grossly negligent or intentionally wrongful acts or omissions of
LB. The foregoing limitation shall also not apply to claims arising under, or
LB's breach of, Clause 7.1 within Clause 7 (LB Warranties and Covenants and
Indemnity); provided, however, that LB's aggregate liability for direct damages
arising out of or in connection with claims arising under, or LB's breach of,
Clause 7.1 within Clause 7 (LB Warranties and Covenants and Indemnity), shall
not exceed the greater of (a) the total maximum aggregate sum payable under this
Agreement for the Services, in accordance with Schedule 3 (Price and Terms of
Payment) attached hereto, and (b) ***.

            14.2 NEITHER PARTY SHALL BE LIABLE TO THE OTHER FOR ANY INCIDENTAL,
PUNITIVE, INDIRECT, OR CONSEQUENTIAL DAMAGES OF ANY KIND, INCLUDING LOST
PROFITS, LOST DATA, LOST REVENUES, AND LOSS OF BUSINESS OPPORTUNITY, WHETHER OR
NOT THE OTHER PARTY WAS AWARE OR SHOULD HAVE BEEN AWARE OF THE POSSIBILITY OF
THESE DAMAGES, EXCEPT THAT THE

                                                          CONFIDENTIAL TREATMENT

                                       31
<PAGE>

FOREGOING LIMITATION SHALL NOT APPLY IN THE CASE OF (a) BREACH OF CLAUSE 8
(CONFIDENTIALITY AND NON-USE) BY EITHER PARTY, (b) PERSONAL INJURY OR DEATH, OR
(c) GROSSLY NEGLIGENT OR INTENTIONALLY WRONGFUL ACTS OR OMISSIONS. The terms of
this Clause 14 shall survive the expiration or termination for whatever reason
of this Agreement.

              [The remainder of this page intentionally left blank]

                                                          CONFIDENTIAL TREATMENT

                                       32
<PAGE>

      AS WITNESS the hands of the duly authorised representatives of the parties
hereto the day and year first above written.

Signed for and on behalf of                    Rene Imwinkelried
                                               ---------------------------------
LONZA BIOLOGICS PLC                            Senior Vice President

                                               Head R & D Pharmaceuticals
                                               ---------------------------------
                                               TITLE

Signed for and on behalf of                    /s/ Peter A. Thompson
                                               ---------------------------------

TRUBION PHARMACEUTICALS, INC.

                                               President & CEO
                                               ---------------------------------
                                               TITLE

                                                          CONFIDENTIAL TREATMENT

                                       33
<PAGE>

                                   SCHEDULE 1
                         DEFINITIONS AND SPECIFICATIONS

DEFINITIONS

For the purpose of this document:

"Cell Line" shall mean the *** cell line created by the Customer expressing
Product.

"Product" shall mean the Small Modular ImmunoPharmaceutical (SMIP) produced by
the Cell Line known as TRU-015.

SPECIFICATIONS

1.1   EXAMPLE OF TYPICAL INITIAL SPECIFICATION FOR BULK PURIFIED PRODUCT

      (These examples are only examples of typical specifications, and shall not
be considered to be the specifications related to the Product)

<TABLE>
<CAPTION>
                         TEST               METHOD         SPECIFICATION
                    ---------------         ------         -------------
<S>                 <C>                     <C>            <C>
                    CHARACTERISTICS
1.1.1                     ***                 ***                ***
1.1.2                     ***                 ***                ***
1.1.3                     ***                 ***                ***
1.1.4                     ***                 ***                ***
1.1.5                     ***                 ***                ***
1.1.6                     ***                 ***                ***
1.1.7                     ***                 ***                ***
1.1.8                     ***                 ***                ***
1.1.9                     ***                 ***                ***
1.1.10                    ***                 ***                ***
1.1.11                    ***                 ***                ***.
1.1.12                    ***                -***                ***-
</TABLE>

1.2   EXAMPLE OF TYPICAL SPECIFICATION FOR BULK FERMENTER HARVEST

      (These examples are only examples of typical specifications, and shall not
be considered to be the specifications related to the Product)

                                                          CONFIDENTIAL TREATMENT

                                       1
<PAGE>

<TABLE>
<CAPTION>
                        TEST                METHOD         SPECIFICATIONS
                        ----                ------         --------------
<S>                     <C>                 <C>            <C>
1.2.1                   ***                  ***                ***
1.2.2                   ***                  ***                ***
1.2.3                   ***                  ***                ***
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       2
<PAGE>

1.3   FINAL BULK PRODUCT DISPOSITION

<TABLE>
<CAPTION>
<S>                <C>                                                    <C>
1.3.1              Final Formulation Buffer:                              ***
1.3.2              Bottling of Bulk Product:
                   1.3.2.1     Containers                                 ***
                   1.3.2.2     Denominations                              ***
                                                                          ***
1.3.3              Product Storage Conditions:                            ***
1.3.4              Shipment Temperature:                                  ***
</TABLE>

1.4   SPECIFICATION FOR CELL BANKS

      STARTING MATERIAL DEFINITION

      An *** of a cryopreserved *** will be created from the Cell Line provided
by the Customer and stored in individual ampoules in liquid nitrogen
refrigerators.

      GENERAL *** SPECIFICATION

      In order for the *** to be accepted into LB's cGMP facility, the following
testing is required and the appropriate specifications achieved.

<TABLE>
<CAPTION>
                        TEST                METHOD         SPECIFICATIONS
                        ----                ------         --------------
<S>                     <C>                 <C>            <C>
1.4.1                   ***                   ***                    ***
                                              ***
                        ***                   ***                    ***
                                              ***
1.4.2                   ***                   ***                    ***
1.4.3                   ***                   ***                    ***
1.4.4                   ***                   ***                    ***
1.4.5                   ***                   ***                    ***
</TABLE>

                                                          ONFIDENTIAL TREATMENTS

                                       3
<PAGE>

                                   SCHEDULE 2
                                    SERVICES

2.    SERVICES

2.1   SUPPLY OF CUSTOMER MATERIALS AND CUSTOMER KNOW-HOW

      Prior to commencement of the Services at LB or, if appropriate, prior to
the commencement of the relevant Stage of the Services, the Customer shall
supply LB with the following:

      ***

                                                          CONFIDENTIAL TREATMENT

                                       1
<PAGE>

2.2   ACTIVITIES TO BE UNDERTAKEN BY LB

      ***

                                                          CONFIDENTIAL TREATMENT

                                       2
<PAGE>

                                   SCHEDULE 3
                           PRICE AND TERMS OF PAYMENT

1.0   PRICE

      In consideration for LB carrying out the Services as detailed in Schedule
      2, the Customer shall pay LB as follows:

***

                                                          CONFIDENTIAL TREATMENT

                                       3
<PAGE>

                                   SCHEDULE 3
                           PRICE AND TERMS OF PAYMENT

2.0   PAYMENT

      Payment by the Customer of the Price for each Stage shall be made against
      LB's Invoices that will be issued as follows:

<TABLE>
<S>             <C>
2.1             FOR STAGE 1
                *** upon commencement of Stage 1.
                *** upon issue of the deliverables for Stage 1 to the Customer.

2.2             FOR STAGE 2
                *** upon commencement of Stage 2.
                *** upon issue of the deliverables for Stage 2 to the Customer.

2.3             FOR STAGE 3
                *** upon commencement of Stage 3.
                *** upon issue of the deliverables for Stage 3 to the Customer.

2.4             FOR STAGE 4
                *** upon commencement of Stage 4.
                *** upon issue of the deliverables for Stage 4 to the Customer.

2.5             FOR STAGE 5
                *** upon commencement of Stage 5.
                *** upon issue of the deliverables for Stage 5 to the Customer.

2.6             FOR STAGE 6
                *** upon commencement of Stage 6.
                *** upon issue of the deliverables for Stage 6 to the Customer.

2.7             FOR STAGE 7
                *** upon commencement of Stage 7.
                *** upon issue of the deliverables for Stage 7 to the Customer.

2.8             FOR STAGE 8
                *** upon ampoule thaw of each batch manufactured under Stage 8.
                *** upon issue of the certificate of analysis for each batch
                manufactured under Stage 8.

2.9             FOR STAGE 9
                *** upon commencement of Stage 9.
                *** upon issue of the deliverables for Stage 9 to the Customer.

2.10            FOR STAGE 10
                100% upon issue of each timepoint interim report and upon issue
                of the final report.

2.11            FOR STAGE 11
                *** upon commencement of Stage 11.
                *** upon issue of the deliverables for Stage 11 to the Customer.

2.12            FOR STAGE 12
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       4
<PAGE>
`
<TABLE>
<S>             <C>
                *** upon commencement of Stage 12.
                *** upon issue of the deliverables for Stage 12 to the Customer.

2.13            FOR STAGE 13
                *** upon commencement of Stage 13.
                *** upon issue of the deliverables for Stage 13 to the Customer.

2.14            FOR STAGE 14
                100% upon issue of each timepoint interim report and upon issue
                of the final report.
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       5
<PAGE>

                                   SCHEDULE 4
                                QUALITY AGREEMENT

              [The remainder of this page intentionally left blank]

                                                          CONFIDENTIAL TREATMENT

                                       6
<PAGE>

                                QUALITY AGREEMENT

      This quality agreement ("Quality Agreement") is dated effective as of 8th
January 2004, and it defines the roles and responsibilities for the quality
operations between LONZA BIOLOGICS PLC, the registered office of which is at 228
Bath Road, Slough, Berkshire SL1 4DX, England (herein after referred to as
"LB"), and TRUBION PHARMACEUTICALS, INC., (formerly known as GENECRAFT, INC.) of
2401 4th Avenue, Suite 1050, Seattle, WA 98121, USA (herein after referred to as
the "Customer") with respect to manufacture of Customer's proprietary Small
Modular ImmunoPharmaceutical (SMIP) known as TRU-015 ("TRU-015") under that
certain development and manufacturing services agreement between the parties of
even date herewith (the "Services Agreement") in preparation for regulatory
filings and for human clinical use. When used in this Quality Agreement, the
term "Product" refers to TRU-015 and/or to the form of TRU-015 manufactured
under the Services Agreement, as the context requires.

      This Quality Agreement takes the form of a detailed list of activities
associated with the manufacture, testing and release of Product. Responsibility
for each activity is assigned to either the Customer or LB, or is assigned to
both the Customer and LB, and additional details are provided in the Services
Agreement and in the SOP's referred to in this Quality Agreement.

      This is the Quality Agreement that is referred to in the Services
Agreement. Capitalized terms used but not defined in this Quality Agreement
shall have the meaning given in the Services Agreement. This Quality Agreement
may be amended by written agreement of the parties. In the event of a conflict
between the Quality Agreement and the Services Agreement, the Services Agreement
shall control. This Quality Agreement may be executed in any number of
counterparts, each of which shall for all purposes be deemed an original and all
of which, taken together, shall constitute one and the same instrument. A
facsimile signature shall be deemed to be and shall be as effective as an
original signature.

      The responsibilities and rights of the parties under this Quality
Agreement are set forth below:

a.    OVERALL RESPONSIBILITIES

      This Quality Agreement outlines the responsibilities of the Customer and
LB with respect to the quality assurance of Product manufactured and supplied by
LB for the Customer under the terms of the Agreement.

      This Quality Agreement takes the form of a detailed list of activities
associated with the manufacture, testing and release of Product. Responsibility
for each activity is assigned to either the Customer or LB, or is assigned to
both the Customer and LB.

      This detailed list describes generic quality activities that would be
performed by both parties for Product used in clinical trail supply. The
specific services to be provided by LB will be set out in

                                                          CONFIDENTIAL TREATMENT

                                       1
<PAGE>

the Agreement (and any Amendments to the Agreement) on Price and other terms
acceptable to both parties.

      LB is responsible for ensuring that the quality requirements for Product
are as specified in the approved Product specification and that Product is
manufactured, tested and stored in accordance with current Good Manufacturing
Practices (cGMP) and all applicable US and EU regulations and ICH guidelines.

      The Customer is responsible for shipping and the final review, approval,
and release of product for use in the clinic. The Customer is responsible for
Product development, technical oversight, product specifications and regulatory
agency filings.

b.    SPECIFIC RESPONSIBILITIES

<TABLE>
<CAPTION>
                   ITEM                                                  RESPONSIBILITIES AND RIGHTS
------------------------------------------  ----------------------------------------------------------------------------------
                                                             LB                                         CUSTOMER(1)
                                            ----------------------------------------     -------------------------------------
<S>    <C>                                  <C>                                          <C>
1.0    Organisation and Personnel           -  Ensure adequate number of personnel       -  Right to audit
                                               with appropriate training, skills,
                                               knowledge and experience to
                                               manufacture and test Product in and
                                               Equipment utilities, equipment,
                                               computerised systems and software are
                                               properly designed, validated and
                                               maintained in accordance with cGMP

2.0    Facilities, Utilities and Equipment  -  Ensure facilities, environment,           -  Right to audit
                                               utilities, equipment, computerised
                                               systems and software are properly
                                               designed, validated and maintained in
                                               accordance with cGMP

                                            -  Ensure Product is manufactured and        -  Right to audit
                                               tested only at sites as agreed with
                                               Customer

                                            -  Provide Customer with Drug Master         -  Include Drug Master File reference
                                               File reference that will allow US FDA        into regulatory submissions, as
                                               the ability to  cross-reference other        appropriate
                                               products that are manufactured at
                                               LB's manufacturing and testing
                                               locations
</TABLE>

----------
(1)   Throughout the Quality Agreement, Customer's column includes the phrase
      "right to audit" - the use of this phrase in certain instances but not in
      others does not and shall not imply that Customer's audit rights pursuant
      to Clause 15 below are limited to those boxes where "right to audit"
      appears.

                                                          CONFIDENTIAL TREATMENT

                                        2
<PAGE>

<TABLE>
<CAPTION>
                   ITEM                                                    RESPONSIBILITIES AND RIGHTS
------------------------------------------  -------------------------------------------------------------------------------------
                                                               LB                                         CUSTOMER(1)
                                            ----------------------------------------     ----------------------------------------
<S>    <C>                                  <C>                                          <C>
                                            -  Provide Customer with documentation
                                               that no penicillin is manufactured or
                                               tested at site

3.0    Raw Materials for Process and        -  Source, test and release raw              -  Right to audit; right to review all
       Packaging of Product/Vendor             materials and primary packaging of           raw material specifications, grades
       Qualification Process                   appropriate quality for processing of        and vendors used in manufacture of
                                               Product                                      Product

                                                                                         -  Customer to provide LB with list of
                                                                                            critical raw materials used in
                                                                                            Customer process; update with changes
                                                                                            as necessary

                                            -  Propose and jointly agree                 -  Right to approve vendor, grade and
                                               specifications, vendors and grade of         specifications of critical raw
                                               critical raw materials used in               materials used in Customer process,
                                               Customer process in accordance with          including excipients, and raw
                                               LB policy, with preference for               materials of animal or human origin
                                               non-animal and non-human derived raw
                                               materials

                                            -  Acknowledge and support Customer's
                                               goal not to use any raw materials of
                                               animal or human origin in the
                                               development of Customer process

                                            -  Retain representative samples             -  Right to audit

4.0    Cell Banks                           -  Prepare, characterise and store cell      -
                                               bank(s) if requested by Customer

                                            -  Jointly agree on testing                  -  Jointly agree on testing
                                               specifications and test methods to           specifications and test methods to
                                               enable release of cell banks for use         enable Product manufactured from cell
                                               in LB's multi-product manufacturing          banks to be used in the clinic
                                               facility

                                            -  Perform stability testing of cell         -  Right to audit
                                               bank(s) if requested by Customer and
                                               share data with Customer

                                            IF CELL BANK SUPPLIED BY CUSTOMER

                                            -  Review and approve characterisation       -  Supply cell bank characterisation
                                               data. Store working stock or cell            data for review and approval.
                                               bank                                         Transfer cell bank (or portion
                                                                                            thereof) to LB
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                        3
<PAGE>

<TABLE>
<CAPTION>
                   ITEM                                                    RESPONSIBILITIES AND RIGHTS
------------------------------------------  -------------------------------------------------------------------------------------
                                                               LB                                         CUSTOMER(1)
                                            ----------------------------------------     ----------------------------------------
<S>    <C>                                  <C>                                          <C>
                                            -  Provide shipping validation data if       -  Right to audit
                                               requested by Customer

                                            IN ALL CASES

                                            -  Provide inventory levels periodically
                                               upon request by Customer

5.0    Production Specification             -  With the Customer determine and           -  With LB determine and approve the
                                               approve the following Product                following Product specification(s) as
                                               specification(s) as required:                required:

                                            -  Drug substance (including testing            -  Drug substance (including testing
                                               performed on fermenter contents for             performed on fermenter contents for
                                               adventitious agents)                            adventitious agents)

                                               -  Drug product                              -  Drug product

                                               -  Bulk placebo                              -  Bulk placebo

                                               -  Filled placebo                            -  Filled placebo

6.0    Production and Process Control       -  Make available for review by Customer     -  Right to review
                                               documents relating to facility,
                                               equipment, Process and test methods,
                                               and GMP systems

                                            -  Jointly review and approve Process        -  Jointly review and approve Process
                                               descriptions                                 descriptions

                                            -  Define and perform an in-process          -  Agree in-process testing strategy
                                               control and testing program

                                            -  Using LB templates prepare master         -  Right to review and comment on master
                                               batch records for each processing            batch records
                                               step and provide to Customer for
                                               review and comment. Retain final
                                               master batch record on site at LB

                                            -  Designate unique batch numbers for        -  Right to audit
                                               raw materials, process materials and
                                               Product

                                            -  Manufacture of Product in accordance      -  Right to audit
                                               with Product Specifications, cGMP
                                               standards, batch records, in-process      -  Relevant sections of Customer's
                                               controls and in-process                      regulatory submissions to be made
                                               specifications                               available to LB as appropriate

                                            -  Ensure QA representatives on-site or      -  Right to audit
                                               available at all times during
                                               manufacture and testing of Product
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                        4
<PAGE>

<TABLE>
<CAPTION>
                   ITEM                                                    RESPONSIBILITIES AND RIGHTS
------------------------------------------  -------------------------------------------------------------------------------------
                                                               LB                                         CUSTOMER(1)
                                            ----------------------------------------     ----------------------------------------
<S>    <C>                                  <C>                                          <C>
                                            -  Permit Customer's person on plant to      -  Right to designate 1 of its employees
                                               be present in LB's facility during           or consultants as Customer's person
                                               normal business hours to observe the         on plant, to be present in LB's
                                               Runs and observe LB's performance, at        facility during normal business times
                                               times and for durations to be agreed.        and for durations to be agreed. While
                                               While at LB's facility, Customer's           at LB's hours to observe the Runs and
                                               representative shall comply with all         observe LB's facility, Customer's
                                               of LB's applicable policies and              representative shall comply with
                                               procedures, and, at LB's option,             performance, at all LB's applicable
                                               shall be escorted by LB personnel            policies and procedures, and, at LB's
                                                                                            option, shall be escorted by LB
                                                                                            personnel

                                            -  Perform Product changeover testing of     -  Review and comment on LB's policy for
                                               Product-contacting equipment in              Product changeover testing of
                                               accordance with LB policy                    Product-contacting equipment

7.0    Product Storage, Labeling and        -  Store, label and package the Product      -  Right to audit
       Packaging Prior to Shipment             (including samples) as defined in the
                                               Product Specification                     -  Provide information on shipping
                                                                                            requirements

8.0    Shipment Requirements                -  Ship Product on behalf of Customer to     -  Jointly agree with LB on process for
                                               locations designated by Customer in          shipping requirements
                                               accordance with jointly agreed
                                               process for shipping requirements         -  Right to audit

                                            -  Provide shipping validation data for      -  Acknowledge receipt of Product
                                               Product if requested by Customer
                                                                                         -  Right to audit

9.0    Laboratory Controls (QC)             -  Perform Product release testing           -  Right to audit
                                               against Product Specifications

                                            -  Jointly agree on SOP's describing         -  Jointly agreed on SOP's describing
                                               Product-specific analytical testing          Product-specific analytical testing
                                               methods                                      methods

                                                                                         -  Provide LB with Product-specific
                                                                                            information as it relates to sample
                                                                                            storage, handling and testing
                                                                                            requirements

                                            -  Retesting, where required, will be        -  Review and comment on LB retest
                                               performed in accordance with LB's            procedure. Review OOS reports;
                                               retest procedure. Out of                     comment on corrective and
                                               specification (OOS) Product                  preventative actions
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                        5
<PAGE>

<TABLE>
<CAPTION>
                   ITEM                                                    RESPONSIBILITIES AND RIGHTS
------------------------------------------  -------------------------------------------------------------------------------------
                                                               LB                                         CUSTOMER(1)
                                            ----------------------------------------     ----------------------------------------
<S>    <C>                                  <C>                                          <C>

                                               release testing results will be notified
                                               to the Customer as soon as possible
                                               within 3 business days of the OOS being
                                               confirmed

                                            -  Send samples to Customer for              -  Perform Product potency testing and
                                               additional testing (including potency        provide data to LB; such data will be
                                               testing) in accordance jointly               provided for with LB's information
                                               approved SOP                                 only and not for inclusion into LB's
                                                                                            information only and not for
                                                                                            inclusion into LB's Certificate of
                                                                                            Analysis. Customer to create
                                                                                            Certificate of Analysis for potency
                                                                                            testing results. [Note from Trubion:
                                                                                            This text to clarify that Trubion is
                                                                                            performing the potency testing and
                                                                                            providing the results to LB `FOR
                                                                                            INFORMATION']

                                            -  Retain representative samples of bulk     -  Right to audit
                                               Product from each batch in accordance
                                               with LB SOP

                                            -  If requested by Customer, provide         -  Right to receive copies of raw data
                                               copies of raw data and testing               and testing records
                                               records

                                            -  Take additional representative            -  Request additional samples to be
                                               samples if requested and ship to             shipped as required
                                               Customer

                                            -  Prepare and characterise Product          -  Jointly approve Product reference
                                               reference standard in accordance with        standard Protocol
                                               jointly agreed Protocol, if requested
                                               by Customer                               -  Right to audit

                                            -  Jointly approve Product reference         -  Jointly approved Product reference
                                               standard report                              standard report

10.0   Use of Contract Testing              -  Qualify Contract Testing Laboratories     -  Right to jointly audit
       Laboratories                            for Product release testing in
                                               accordance with LB policy

                                            -  Notify Customer of Contract Testing       -  Consent or reject to the proposed use
                                               Laboratories intended to be used for         of Contract Testing Laboratories
                                               Product release testing

                                            -  Facilitate audit by Customer if           -  Right to audit
                                               requested from time to time
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                        6
<PAGE>

<TABLE>
<CAPTION>
                                                         RESPONSIBILITIES AND RIGHTS
                                   ------------------------------------------------------------------------
             ITEM                                    LB                               CUSTOMER(1)
--------------------------------   --------------------------------------   -------------------------------
<S>      <C>                       <C>                                      <C>
                                   -  If not prohibited by                  -  Right to request, receive
                                      Contract Testing                         and use copies of LB's
                                      Laboratory, provide                      audits of Contract Testing
                                      Customer with copies of                  Laboratories when possible,
                                      LB's audits of Contract                  unless prohibited by
                                      Testing Laboratories when                Contract Testing
                                      possible, if requested                   Laboratories

11.0     Product Release and Lot   -  Review batch record for               -  Right to review completed
         Review                       compliance with cGMP,                    and reviewed Product batch
                                      manufacturing controls, and              records
                                      with the Product
                                      Specifications

                                   -  Provide Customer with a               -  Right to review
                                      copy of the Process
                                      documentation including,
                                      main operational steps from
                                      the completed batch
                                      record.  This will include
                                      Product analysis, a summary
                                      of batch related deviations
                                      and environmental
                                      monitoring summaries, as
                                      well as process data, as
                                      requested

                                   -  If requested by Customer,             -  Right to request and
                                      send full copies of actual               receive full copies of
                                      deviations                               actual deviations

                                   -  Prepare manufacturer's                -  Prepare Certificate of
                                      Certificate of Analysis,                 Analysis and Certificate of
                                      including related                        Compliance for release of
                                      Certificate of Compliance                product for use in human
                                                                               clinical trials

                                   -  Release or reject Product             -  Release of reject Product
                                                                               for use in human clinical
                                                                               trials

12.0     Deviations and Failed     -  Initiate investigations,              -  Right to audit
         Run Investigations and       evaluate and define follow
         Reports                      up actions and final
                                      approval of deviations and
                                      failure investigations

                                   -  Notify Customer of all                -  Review significant
                                      significant deviations                   deviations; comment on
                                      immediately and within at                corrective and preventative
                                      least 3 business days of                 actions
                                      the event being assigned as
                                      significant, and send
                                      Customer the related
                                      documentation.  (A
                                      significant deviation is
                                      defined in standard
                                      operating procedure 3150)

                                   -  Notify Customer of failed             -  Review failure
                                      runs immediately and within              investigation report and
                                      at least 3 business days of              comment on corrective and
                                      failure being identified                 preventative actions
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       7

<PAGE>

<TABLE>
<CAPTION>
                                                         RESPONSIBILITIES AND RIGHTS
                                   ------------------------------------------------------------------------
             ITEM                                    LB                               CUSTOMER(1)
--------------------------------   --------------------------------------   -------------------------------
<S>      <C>                       <C>                                      <C>
                                   -  Immediately and within at least 3
                                      business days of event being
                                      identified, notify Customer of any
                                      events which may impact batches
                                      previously shipped or released

13.0     Change Control            -  Jointly agree on SOP for              -  Jointly agree SOP for
         Procedures                   change control procedures                change control procedures
                                      between the 2 companies                  between the 2 companies
                                      that describes the intended              that describes the intended
                                      use of each company's                    use of each company's
                                      independent change control               independent change control
                                      system                                   systems

                                   CUSTOMER PROPOSED CHANGES

                                   -  Process Product-specific              -  Propose Customer
                                      change through change                    Product-specific changes
                                      control and notify Customer              and provide rationale in
                                      of change approval.  If                  writing
                                      change rejected, discuss
                                      reasons for rejection with
                                      Customer

                                   -  Approve proposed
                                      Product-specific changes
                                      prior to implementation

                                   LB PROPOSED CHANGES

                                   -  Proposed Product-specific             -  Process Product-specific
                                      changes and provide                      change through change
                                      rationale for change to                  control and notify LB of
                                      process descriptions; test               change approval.  If change
                                      methods; sampling plans;                 rejected, discuss reasons
                                      specifications for key raw               for rejection with LB
                                      materials (animal and / or
                                      human derived raw                     -  Approve proposed
                                      materials, chromatography                Product-specific changed
                                      resins and final                         prior to implementation
                                      formulation excipients);
                                      Product specification(s)
                                      and stability programme,
                                      in-process controls and
                                      other key processing steps

                                   -  Inform Customer of changes            -  Right to audit
                                      to key personnel as
                                      identified in Appendix 1

                                   -  Inform Customer of changes            -  Right to audit
                                      to major items of
                                      equipment, premises and
                                      utilities used for
                                      manufacture of Product

                                   ALL CHANGES

                                   -  With Customer define                  -  With LB define strategy for
                                      strategy for                             notifying change to
                                                                               Regulatory
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       8

<PAGE>

<TABLE>
<CAPTION>
                                                         RESPONSIBILITIES AND RIGHTS
                                   ------------------------------------------------------------------------
             ITEM                                    LB                                CUSTOMER(1)
--------------------------------   --------------------------------------   -------------------------------
<S>                                <C>                                      <C>
                                      notifying change to Regulatory           Agency as appropriate
                                      Agency as appropriate (see Section       (see Section 20.0, below,
                                      20.0, below, Regulatory                  Regulatory Submissions)
                                      Submissions)

                                   -  Inform Customer of Product            -  Ensure Product is not
                                      batches manufactured with                distributed until
                                      the change until regulatory              Regulatory approval
                                      approval obtained, if                    obtained, if required
                                      required

                                   -  Cooperate with Customer in            -  Cooperate with LB in
                                      connection with change                   connection with change
                                      controls; respect                        controls; respect LB's
                                      Customer's change controls,              change controls, and, as
                                      and, as appropriate, use it              appropriate, use it to
                                      to initiate LB's change                  initiate Customer's change
                                      controls                                 controls

14.0     Reprocessing / Rework     -  Processing to be performed            -  Review and comment on LB's
                                      in accordance with LB SOP.               reprocessing / rework SOP;
                                      With Customer agree on                   with LB agree on
                                      reprocessing / rework                    reprocessing / rework
                                      procedures, where possible               procedures, where possible
                                      prior to execution                       prior to execution

                                   -  Provided documented reason            -  Right to audit
                                      and justification for
                                      reprocessing / rework event

                                   -  With the Customer agree on            -  With LB agree the
                                      the appropriate testing                  appropriate testing
                                      required prior to Product                required prior to Product
                                      release                                  release

15.0     Audit                     -  Permit Customer                       -  Provide reasonable notice
                                      representatives access as                of intention to audit
                                      reasonably required to
                                      conduct a cGMP compliance             -  Right to 2 standard cGMP
                                      audit, including access to               compliance audits per year,
                                      warehousing, manufacturing               plus right to additional
                                      areas, laboratories, and                 "for cause" audits
                                      manufacturing records and
                                      documents, including SOPs             -  Right to audit each batch
                                      (unless they contain                     record
                                      specific LB proprietary
                                      information eg media                  -  Hold an exit meeting to
                                      formulations), and                       discuss observations
                                      personnel, for audit
                                      purposes.  Customer                   -  Provide an audit report
                                      representatives to be                    within 30 days of
                                      accompanied at all times by              completion of audit
                                      LB personnel

                                   -  Two standard cGMP
                                      compliance audits permitted
                                      per year, with an audit not
                                      to exceed 3 working days
                                      and 2 groups of auditors.
                                      Additionally the Customer may
</TABLE>

                                                          CONFIDENTIAL TREATMENT
                                       9

<PAGE>

<TABLE>
<CAPTION>
                                                         RESPONSIBILITIES AND RIGHTS
                                   ------------------------------------------------------------------------
             ITEM                                    LB                               CUSTOMER(1)
--------------------------------   --------------------------------------   -------------------------------
<S>      <C>                       <C>                                      <C>
                                      request "for cause"
                                      audits to address
                                      production of Product
                                      quality issues

                                   -  One 2 day audit for each
                                      batch record if requested
                                      by Customer

                                   -  Allow the Customer to
                                      observe operations related
                                      to Product manufacturing
                                      and testing providing other
                                      Customer's confidentiality
                                      is respected

                                   -  Provide a written response to all
                                      audit findings that require
                                      corrective action within 30 days of
                                      receipt of the audit report.
                                      Response to include expected
                                      timelines

16.0     Product Complaints and    -  Respond to requests for               -  Receive and investigate
         Recall                       data to assist Customer in               Product complaints and
                                      their investigation.  Agree              instigate Product recall as
                                      a time scale for response                appropriate

17.0     Batch Records             -  Retain records associated             -  Right to audit
                                      with manufacture and
                                      testing records of Product
                                      including records
                                      associated with the
                                      inspection and release of
                                      raw materials and primary
                                      packaging components of the
                                      Product for 5 years from
                                      the date of manufacture of
                                      Product.  Date of
                                      manufacture is defined as
                                      the date Product is
                                      dispensed in to the bulk
                                      product container)

                                   -  Notify Customer of intent             -  Customer to approve
                                      to destroy records with                  destruction or request
                                      option to send records to                receipt of records
                                      Customer

18.0     Process Validation /      -  With Customer define                  -  With LB define process
         Stability Studies            process validation plans                 validation plans for
                                      for Product including                    Product including
                                      analytical validation and                analytical validation and
                                      stability studies                        stability studies

                                   WHERE PROCESS VALIDATION IS
                                   PERFORMED BY LB

                                   -  Provide Customer with                 -  Approve Product specific
                                      Product specific validation              validation protocol(s)
                                      protocol(s) for                          including stability protocols
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       10
<PAGE>
<TABLE>
<CAPTION>
                                                   RESPONSIBILITIES AND RIGHTS
                         -------------------------------------------------------------------------------
          ITEM                               LB                                 CUSTOMER(1)
----------------------   ----------------------------------------   ------------------------------------
<S>  <C>                 <C>                                        <C>
                            approval prior to execution

                         -  Provide Customer with draft             -  Review and comment on Product
                            Product specific validation report(s)      specific validation report(s)
                            for review and comment                     including stability reports

                         -  Issue Customer with copy of             -
                            final Product specific validation
                            report(s)

                         WHERE PROCESS VALIDATION IS
                         PERFORMED BY CUSTOMER

                         -  Incorporate specifications in           -  Provide LB with process
                            cGMP documentation and regulatory          validation reports
                            submissions

19.0 Regulatory Agency   GMP INSPECTIONS
     Inspection
                         -  Inform Customer of Regulatory           -  For Regulatory Agency inspections
                            Agency inspections or regulatory           or regulatory action affecting
                            action affecting manufacture, testing      Product, provide assistance
                            or storage of Product                      when requested by LB

                         -  Notify Customer of inspection           -  Comment on proposed inspection
                            observations (including Deficiency         responses to observations
                            Letters) affecting the Product,            relevant to Product
                            process or systems relating to the
                            Product

20.0 Regulatory          WHERE A DATA PACK IS PROVIDED BY LB TO
     Submissions         SUPPORT CUSTOMER'S CLINICAL TRIAL
                         APPLICATION

                         INITIAL APPLICATION, AMENDMENTS AND
                         RESPONSES TO QUESTIONS

                         -  Provide Customer with data pack         -  Prepare and provide LB with
                            covering activities performed by LB        copy of relevant sections of
                                                                       clinical trial application for
                         -  Review and comment on relevant             review and comment prior to
                            sections of clinical trial                 submission to Regulatory Agency
                            application
                                                                    -  Provide LB with copy of relevant
                                                                       sections as submitted to
                                                                       Regulatory Agencies

                         TELECONFERENCES AND MEETINGS WITH THE
                         REGULATORY AGENCIES

                         -  Attend teleconferences and              -  Arrange for LB personnel to have
                            meetings between the Customer and          option to attend teleconferences
                            Regulatory Agencies arranged               and meetings between Customer
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       11
<PAGE>

<TABLE>
<CAPTION>
                                                   RESPONSIBILITIES AND RIGHTS
                         -------------------------------------------------------------------------------
          ITEM                               LB                                 CUSTOMER(1)
----------------------   ----------------------------------------   ------------------------------------

<S>                      <C>                                        <C>
                            to specifically discuss topics             and Regulatory Agencies to
                            relating to LB's responsibilities          specifically discuss topics
                                                                       relating to LB's responsibilities
</TABLE>

                                                          CONFIDENTIAL TREATMENT

                                       12
<PAGE>

QUALITY APPROVAL

LONZA BIOLOGICS PLC

Name: /s/ Rene Imwinkleried                Signature: /s/ Rene Imwinkleried
      --------------------------                      --------------------------

Title: Senior Vice President               Date: (illegible) Apr 2004

TRUBION PHARMACEUTICALS INC.

Name: Peter A. Thompson, MD                Signature: /s/ Peter Thompson
                                                      --------------------------

Title: President & CEO                     Date: 4/23/2004

                                                          CONFIDENTIAL TREATMENT

                                       13
<PAGE>

                       APPENDIX 1 TO THE QUALITY AGREEMENT

CUSTOMER                              LONZA

SENIOR VICE PRESIDENT,                HEAD OF LONZA CONTRACT MANUFACTURING:
RESEARCH AND DEVELOPMENT:
Kendall M Mohler PhD                  Mr Rene Imwinkleried
Senior Vice President                 Head of Lonza Contract Manufacturing
Research and Development              Lonza Biologics
Trubion Pharmaceuticals Inc           228 Bath Road
2401 Fourth Avenue, Suite 1050        Slough SL1 4DX
Seattle, WA 98121                     UK
USA
Tel:+1 206 838 0514                   Tel:+44 1753 777082
Fax: +1 206 838 0503                  Fax: +44 1753 716644
Email: kmoh1er@trubion.com            Email: Rene.lmwinkleried@Lonza,com

HEAD OF QUALITY:                      HEAD OF QUALITY:
Sally R Gould                         Mrs Eleanor Taaffe
Senior Director, Regulatory Affairs   Head of Quality and Regulatory Affairs
Trubion Pharmaceuticals Inc           Lonza Biologics
2401 Fourth Avenue, Suite 1050        228 Bath Road
Seattle, WA 98121                     Slough SL1 4DX
USA                                   UK
Tel:+1206 838 0510                    Tel:+44 1753 777067
Fax:+1 206 838 0503                   Fax;+44 1753 777001
Email: sqould@trubion.com             Email: Eleanor.Taaffe@Lonza.com

HEAD OF MANUFACTURING:                DIRECTOR OF MANUFACTURING, UK:
Dale H Scott                          Dr Michael E Brown
Vice President, Development           Head of Manufacturing
Trubion Pharmaceuticals Inc           Lonza Biologics
2401 Fourth Avenue, Suite 1050        228 Bath Road
Seattle, WA 98121                     Slough SL1 4DX
USA                                   UK
Tel: +1 206 838 0513                  Tel: +44 1753 777000
Fax: +1 206 838 0503                  Fax: +44 1753 777001
Email: dscott@trubion.com             Email: Mike.Brown@Lonza.com

QUALITY CONTROL MANAGER:              QUALITY CONTROL MANAGER:
Raj Dua PhD                           Dr Steve Flatman
Director, Product Development         Head of QC and Analytical
Trubion Pharmaceuticals Inc           Lonza Biologics
2401 Fourth Avenue, Suite 1050        228 Bath Road
Seattle, WA 98121                     Slough SL1 4DX
USA                                   UK
Tel: +1 206 838 0512                  Tel: +44 1753 777000
Fax: +1 206 838 0503                  Fax: +44 1753 777001
Email: rdua@trubion.com               Email: Steve.Flatman@Lonza.com

                                                          CONFIDENTIAL TREATMENT

                                       14
<PAGE>

                                   SCHEDULE 5

                                  SPECIAL TERMS

        OUTLINE OF TERMS FOR THE TECHNOLOGY TRANSFER OF THE PROCESS FOR
             MANUFACTURE OF PRODUCT TO CUSTOMER OR TO A THIRD PARTY

      This Schedule 5 is the Schedule that is referred to in Clause 9.9 of the
Development and Manufacturing Services Agreement ("Development and Manufacturing
Services Agreement") between LONZA BIOLOGICS PLC as "LB" and TRUBION
PHARMACEUTICALS, INC. as "Customer" related to the Technology Transfer of the
Process to Customer or a third party. This Schedule 5 sets forth some additional
commercial terms for any Technology Transfer. All capitalized terms used but not
defined in this Schedule 5 shall have the meanings given in the Development and
Manufacturing Services Agreement.

      ***
                                                          CONFIDENTIAL TREATMENT

                                        1

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