Document:

<PAGE>

                                                                   EXHIBIT 10.23

                                AMENDMENT No. 10

                                       to

                        THE DEVELOPMENT AND MANUFACTURING
                               SERVICES AGREEMENT

                              Dated 08 January 2004

                                     Between

                               LONZA BIOLOGICS PLC

                                       and

                          TRUBION PHARMACEUTICALS, INC.

                                                          CONFIDENTIAL TREATMENT

<PAGE>

     THIS AMENDMENT No. 10 ("Tenth Amendment") is made the 20th day of December
2005 BETWEEN

     LONZA BIOLOGICS PLC of 228 Bath Road, Slough, Berkshire SL1 4DX, England
(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:

     1.0 Two new Stages, Stage 32 and Stage 33, shall be added to Schedule 2 of
the Agreement to read as follows:

                                                          CONFIDENTIAL TREATMENT

<PAGE>

     32.  "Stage 32 - ***

          32.1 Objective

     ***

          32.2 Activities

     ***

          32.3 Timescale

     This Stage may commence upon issue of the protocol.

     This Stage shall be complete with the issue of the report of activities. It
is estimated that this report shall be issued *** from commencement of this
Stage.

     33.  Stage 33 - ***

          33.1 Objectives

     ***

          33.2 Activities

     ***

          33.3 Timescale

     This Stage may commence as soon as Product is available and shall be
complete on issue of the final report of activities (Activity 33.2.4) and it is
estimated that this will be issued *** from the preparation of the protocol.
From issue of the protocol it is estimated that the elapsed time until the
Customer review of the report is ***.

     Note: The Customer shall review the draft protocol and the audited report
(activity 33.2.1 and 33.2.4) within *** of receiving the document from LB. If
the Customer's comments are not returned to LB within this time Lonza reserves
the right to issue the protocol or final study report"

                                                          CONFIDENTIAL TREATMENT

                                      -2-

<PAGE>

     SCHEDULE 3 TO THE AGREEMENT SHALL BE AMENDED TO INCLUDE PROVISION FOR
PAYMENT FOR THE ABOVE MENTIONED ADDITIONAL SERVICES, AS SET OUT BELOW HERETO.
INVOICES FOR THESE ADDITIONAL SERVICES SHALL BE ISSUED, AND CUSTOMER PAYMENTS
SHALL BE MADE, IN ***

     "1. PRICE

     ***

     2. PAYMENT

     FOR STAGE 32

     *** upon commencement of Stage 32.

     *** upon completion of Stage 32.

     Testing Laboratory charges will be invoiced separately.

     FOR STAGE 33

     *** upon commencement of Stage 33.

     *** upon completion of Stage 33

     Testing Laboratory charges will be invoiced separately"

                                                          CONFIDENTIAL TREATMENT

                                      -3-

<PAGE>

     SAVE AS HEREIN PROVIDED ALL OTHER TERMS AND CONDITIONS OF THE AGREEMENT
SHALL REMAIN IN FULL FORCE AND EFFECT.

     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
LONZA BIOLOGICS PLC                     /s/ Ian Elvins
                                        ----------------------------------------
                                        VP Global Biologics Quality
                                        TITLE

Signed for and on behalf of
TRUBION PHARMACEUTICALS, INC            /s/ Kendall M. Mohler
                                        ----------------------------------------
                                        Senior VP, Research & Development
                                        TITLE

                                                          CONFIDENTIAL TREATMENT

                                      -4-<PAGE>

                                                                   EXHIBIT 10.24

                                AMENDMENT No. 11

                                       to

                        THE DEVELOPMENT AND MANUFACTURING
                               SERVICES AGREEMENT

                              Dated 08 January 2004

                                     Between

                               LONZA BIOLOGICS PLC

                                       and

                          TRUBION PHARMACEUTICALS, INC.

                                                          CONFIDENTIAL TREATMENT

<PAGE>

THIS AMENDMENT No. 11 ("Eleventh Amendment") is made the 31st day of March 2006
BETWEEN

LONZA BIOLOGICS PLC of 228 Bath Road, Slough, Berkshire SL1 4DX, England
(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.   SCHEDULE 1 OF THE AGREEMENT SHALL BE AMENDED TO INCLUDE THE FOLLOWING:

(a)  ***

***.

<TABLE>
<CAPTION>
TEST                    METHOD
 NO.   CRITERION   (LB SOP NUMBER)   SPECIFICATION
----   ---------   ---------------   -------------
<S>    <C>         <C>               <C>
Characteristics
***    ***         ***               ***
***    ***         ***               ***
***    ***         ***               ***
***    ***         ***               ***
***    ***         ***               ***
</TABLE>

<TABLE>
<CAPTION>
TEST                    METHOD
 NO.   CRITERION   (LB SOP NUMBER)   SPECIFICATION
----   ---------   ---------------   -------------
<S>    <C>         <C>               <C>
Identity
***    ***         ***               ***
</TABLE>

                                                          CONFIDENTIAL TREATMENT

<PAGE>

<TABLE>
<S>    <C>         <C>               <C>
***
***    ***         ***               ***
***    ***         ***               ***
</TABLE>

<TABLE>
<CAPTION>
TEST                    METHOD
 NO.   CRITERION   (LB SOP NUMBER)   SPECIFICATION
----   ---------   ---------------   -------------
<S>    <C>         <C>               <C>
Impurities
***    ***         ***               ***
***    ***         ***               ***
***    ***         ***               ***
***
***    ***         ***               ***
***    ***         ***               ***
</TABLE>

<TABLE>
<CAPTION>
TEST                    METHOD
 NO.   CRITERION   (LB SOP NUMBER)   SPECIFICATION
----   ---------   ---------------   -------------
<S>    <C>         <C>               <C>
Safety
***    ***         ***               ***
***    ***         ***               ***
</TABLE>

Storage and shipping information

     Final Formulation Buffer: *** (Pharmaceutical Grade)

     Bottling of Bulk Product:

          Primary containers: ***

          Denominations:

               ***

          Product Storage Conditions: ***.

          Shipment Temperature: ***.

                                                          CONFIDENTIAL TREATMENT

                                       -2-

<PAGE>

          Customer samples (removed during the middle of dispensing):

               To be agreed by LB and Customer.

     Shipment Temperature: ***.

2.   SCHEDULE 2 OF THE AGREEMENT SHALL BE AMENDED TO AMEND STAGE 27 AND ADD
     STAGES 34 AND 35 TO READ AS FOLLOWS:

     "27 STAGE 27 ***

     BACKGROUND

          ***

          27.1 OBJECTIVES

               ***

          27.2 ACTIVITIES

               ***

          27.3 TIMESCALE

               This stage may commence upon receipt of the subsequent Cell Line
               at LB and it is estimated that this stage shall be complete
               approximately *** from commencement of the stage.

     34.  STAGE 34 ***

     BACKGROUND

          ***

          34.1 OBJECTIVES

          ***

          34.2 ACTIVITIES

               ***

          34.3 TIMESCALE

               This Stage can commence as soon as the relevant information is
               received from the Customer. This Stage shall be an ongoing
               process but will be set as to not be a rate-limiting step.

                                                          CONFIDENTIAL TREATMENT

                                       -3-

<PAGE>

               It is estimated that this Stage shall be complete *** from the
               commencement of this Stage.

               Note: Following activity 34.2.6, any additional work above and
                    beyond the scope identified in Stage 34 herein would be
                    subject to agreement by both parties and would be carried
                    out under terms and conditions to be agreed.

     35   STAGE 35 ***

          BACKGROUND

          ***

          35.1 OBJECTIVES

               ***

          35.2 ACTIVITIES

               ***

          35.3 TIMESCALE

               This Stage may commence when:

               -    the *** of the Customer Cell Lines are available and
                    approved by LB for use, and

               -    sufficient information is available for the Services to
                    proceed.

               This Stage shall be complete upon issue of the summary report to
               the Customer. It is estimated that this report shall be issued
               *** from commencement of this Stage.

                                                          CONFIDENTIAL TREATMENT

                                       -4-

<PAGE>

SCHEDULE 3 TO THE AGREEMENT SHALL BE AMENDED TO INCLUDE PROVISION FOR PAYMENT
FOR THE ABOVE MENTIONED ADDITIONAL SERVICES, AS SET OUT BELOW HERETO. INVOICES
FOR THESE ADDITIONAL SERVICES SHALL BE ISSUED, AND CUSTOMER PAYMENTS SHALL BE
MADE, ***:

     "1.  Price

     ***

     2.   Payment

          FOR STAGE 27

          *** upon commencement of Stage 27.

          *** upon completion of Stage 27.

          FOR STAGE 34

          *** upon commencement of Stage 34.

          *** upon completion of Stage 34

          FOR STAGE 35

          *** upon commencement of Stage 35.

          *** upon completion of Stage 35

          ***

                                                          CONFIDENTIAL TREATMENT

                                       -5-

<PAGE>

                                                                           LONZA

SAVE AS HEREIN PROVIDED ALL OTHER TERMS AND CONDITIONS OF THE AGREEMENT SHALL
REMAIN IN FULL FORCE AND EFFECT.

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
LONZA BIOLOGICS PLC                     /s/ Ian Elvins
                                        ----------------------------------------
                                        VP Global Biologics Quality
                                        TITLE

Signed for and on behalf of
TRUBION PHARMACEUTICALS, INC            /s/ Kendall M. Mohler
                                        ----------------------------------------
                                        Senior VP, Research & Development
                                        TITLE

                                                          CONFIDENTIAL TREATMENT

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