The nonrandomized, open label, uncontrolled, single-group assignment clinical trial is designed to evaluate the safety and efficacy of TRU-015 in subjects with NHL

SEATTLE, WA, USA | December 10, 2007 | Trubion Pharmaceuticals, Inc. (Nasdaq: TRBN), today announced that Wyeth Pharmaceuticals has initiated a Phase I/II clinical trial of TRU-015, Trubion’s lead Small Modular ImmunoPharmaceutical (SMIP(TM)) drug candidate, for the treatment of non-Hodgkin’s lymphoma (NHL). The nonrandomized, open label, uncontrolled, single-group assignment clinical trial is designed to evaluate the safety and efficacy of TRU-015 in subjects with NHL. Trubion is co-developing TRU-015 and other CD20-directed therapies with Wyeth Pharmaceuticals, a division of Wyeth (NYSE: WYE).

"We believe that TRU-015 may be a valuable tool in the treatment of NHL, and we are looking forward to working with Wyeth as this development program moves forward," said Peter Thompson, M.D., FACP, president, chief executive officer and chairman of Trubion.

TRU-015 Phase I/II Clinical Trial Protocol

The Phase I/II clinical trial is expected to enroll approximately 120 NHL subjects who have undergone two or more prior therapies and have relapsed or refractory disease. Efficacy will be evaluated according to disease response and progression status per the International Response Criteria for NHL. Participants will receive an escalating dose of four weekly infusions of TRU-015. Once a maximum tolerated dose is confirmed, or once a maximum dose to be studied is determined to be safe and well tolerated, an expanded cohort of subjects with relapsed follicular NHL will be evaluated for efficacy.

Trubion’s TRU-015 is also being developed for the treatment of rheumatoid arthritis and systemic lupus erythematosus.

About TRU-015 and SMIP Therapeutics

Trubion and Wyeth Pharmaceuticals are developing SMIP therapeutics directed to CD20, an antigen present on B cells. Trubion’s SMIP drug candidates represent a novel class of immunotherapeutics that the company believes possess enhanced drug properties over monoclonal and recombinant antibodies. SMIP product candidates are novel single-chain polypeptide proteins designed using Trubion’s custom drug assembly technology. Trubion’s current product candidates bind to specific antigen targets on a cell’s surface that have been clinically validated as important in disease management either by existing products or by potential products in clinical trials.

About Non-Hodgkin’s Lymphoma

NHL is a cancer of the lymphoid tissue, which is part of the lymphatic system. NHL directly affects the lymphocytes, the white blood cells responsible for immunity. In the United States, 85 percent of all cases of NHL come from B lymphocytes (B cells) and 15 percent from T lymphocytes (T cells). About 63,190 new cases of NHL will occur this year in the United States according to The American Cancer Society. NHL is one of the most rapidly increasing types of cancer in the United States, having more than doubled in incidence since the 1970s according to the Mayo Clinic.

About Trubion

Trubion is a biopharmaceutical company creating a pipeline of product candidates to treat autoimmune disease and cancer. The company’s product candidates are novel proteins known as single-chain polypeptides and are designed using its SMIP custom drug assembly technology. In December 2005, the company entered into a collaboration agreement with Wyeth for the development and worldwide commercialization of certain therapeutics, including TRU-015. In addition, Trubion’s TRU-016 program targets CD37, an antigen present on B cells, for the treatment of chronic lymphocytic leukemia and non-Hodgkin’s lymphoma. The company filed an IND for TRU-016 in the fourth quarter of 2007. Trubion currently retains all development and commercialization rights for the TRU-016 program. For additional information visit http://www.trubion.com.

Forward-Looking Statements

Certain statements in this release may constitute "forward-looking statements" within the meaning of Section 21E of the Securities Exchange Act of 1934 and Section 27A of the Securities Act of 1933. These statements include, but are not limited to, those related to the company’s future clinical development programs and the timing thereof, the company’s expected financial and operating results, future clinical development plans, the details of the clinical trials and the results and timing thereof, and the timing of regulatory applications and action. These statements are based on current expectations and assumptions regarding future events and business performance and involve certain risks and uncertainties that could cause actual results to differ materially. These risks include, but are not limited to, risks associated with the company’s Wyeth collaboration, including Wyeth’s control over development timelines, and such other risks as identified in the company’s quarterly report on Form 10-Q for the period ended Sept. 30, 2007, and from time to time in other reports filed by Trubion with the U.S. Securities and Exchange Commission. These reports are available on the Investors page of the company’s corporate Web site at http://www.trubion.com. Trubion undertakes no duty to update any forward-looking statement to conform the statement to actual results or changes in the company’s expectations.

SOURCE: Trubion Pharmaceuticals, Inc.