AMENDMENT No. 7 to THE DEVELOPMENT AND MANUFACTURING SERVICES AGREEMENT

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                                                                   Exhibit 10.23
                                 AMENDMENT No. 7

                                       to

                        THE DEVELOPMENT AND MANUFACTURING
                                SERVICES AGREEMENT

                              Dated 08 January 2004

                                     Between

                               LONZA BIOLOGICS ***

                                       and

                          TRUBION PHARMACEUTICALS, INC.

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THIS AMENDMENT No. 7 ("Seventh Amendment") is made the 12th day of May 2005

BETWEEN

LONZA BIOLOGICS *** of *** (hereinafter referred to as "LB"), and

TRUBION PHARMACEUTICALS, INC., of 2401 4th Avenue, Suite 1050, Seattle, WA
98121, USA (herein after referred to as the "Customer")

WHEREAS

A.    LB and the Customer entered into a development and manufacturing services
     agreement ("the Agreement") dated 08 January 2004, pursuant to which LB
     agreed to provide Services to the Customer, and,

B.    The Customer now wishes LB to perform additional services under the
     Agreement, and,

C.    LB is willing to perform such additional services on the terms set out in
     the Agreement, and,

D.    The parties wish to amend the Agreement in accordance with Clause 13.5
     thereto.

NOW THEREFORE IT IS HEREBY AGREED as follows:

     1.    TWO NEW STAGES, STAGES 27 AND 28 SHALL BE ADDED TO SCHEDULE 2 OF THE
          AGREEMENT TO READ AS FOLLOWS:

     "STAGE 27 ***

      BACKGROUND

     ***

     27.1 OBJECTIVES

     ***

     27.2 ACTIVITIES

     ***

     27.3 DELIVERABLES

          27.3.1 A copy of the *** prepared in activity 27.2.1.

          27.3.2 Appropriate samples from the *** as agreed