Trubion Announces Initiation of Phase 2b Study of TRU-015 for the Treatment of Rheumatoid Arthritis

SEATTLE, May 7 /PRNewswire-FirstCall/ -- Trubion Pharmaceuticals Inc. today announced that its partner, Wyeth Pharmaceuticals, a division of Wyeth , has commenced patient dosing in the next Phase 2b clinical trial of TRU-015 in patients with rheumatoid arthritis (RA). In collaboration with Trubion, Wyeth Pharmaceuticals is developing TRU-015, SBI-087 and other CD20-directed products.

The randomized, parallel, double-blind, placebo-controlled, dose regimen-finding study will evaluate the safety and efficacy of two dosing regimens administered to approximately 216 patients with active, seropositive RA on a background of methotrexate. The primary outcome measurement for the TRU-015 Phase 2b study will be the American College of Rheumatology (ACR) 50 response measured at 24 weeks. Secondary outcome measurements will be ACR 20 and 70 and DAS-28 responses.

"Data reported previously demonstrates TRU-015's ability to significantly improve RA signs and symptoms, and maintain response rates with repeat administration of single doses given every six months," said Peter Thompson, M.D., FACP, president, CEO and chairman of Trubion. "This study is designed to help us identify an induction, or initial, dosing regimen and allow us to further establish the most effective treatment regimen for TRU-015. We believe this study has been designed in a way that could support a registration package, and we look forward to the results of this evaluation."

With the addition of SBI-087 -- Trubion's next-generation, fully humanized CD20-directed SMIPTM -- Trubion's pipeline now includes two compounds under development for the treatment of autoimmune and inflammatory diseases. Trubion and Wyeth are leveraging Trubion's SMIPTM technology to create a portfolio of product candidates with customized mechanisms of action in an effort to optimize patient safety, efficacy and convenience.

About Trubion

Trubion is a biopharmaceutical company that is creating a pipeline of novel protein therapeutic product candidates to treat autoimmune and inflammatory diseases and cancer. The company's mission is to develop a variety of first-in-class and best-in-class product candidates, customized for optimal safety, efficacy, and convenience that it believes may offer improved patient experiences. Trubion's current product candidates are novel single-chain protein, or SMIP(TM), therapeutics, and are designed using its custom drug assembly technology. Trubion's product pipeline includes CD20-directed candidates such as TRU-015 and SBI-087 for autoimmune and inflammatory diseases, developed under the company's Wyeth collaboration. Trubion's product pipeline also includes Trubion's proprietary product candidate, TRU-016, a novel CD37-targeted therapy for the treatment of B-cell malignancies that is currently in Phase 1/2 clinical evaluation. In addition to Trubion's current product candidates, the company is also developing additional alliance and proprietary product candidates that build on its product development experience. More information is available in the investors section of Trubion's website: investors.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 the risk that the current Phase 2b study of TRU-015 does not help the Company and Wyeth identify a TRU-015 induction dosing regimen or further establish the most effective treatment regimen for TRU-015, the risks that the Company is unable to advance its clinical development programs and regulatory applications and action at the rate it expects, the risk that the Company does not achieve the financial and operating results it expects and such other risks as identified in the company's quarterly report on Form 10-K for the period ended Dec. 31, 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.

For more information, contact: Trubion Pharmaceuticals Inc. Jim DeNike Senior Director, Corporate Communication (206) 838-0500 jdenike@trubion.com Waggener Edstrom Worldwide Healthcare Amy Petty Senior Account Executive (617) 576-5788 amyp@waggeneredstrom.com

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