IDEC Pharmaceuticals Initiates Phase II Study With Primatized Antibody Clenoliximab in Patients With Rheumatoid Arthritis.

Business Editors & Health/Medical Writers

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SAN DIEGO--(BW HealthWire)--Aug. 7, 2000

IDEC Pharmaceuticals (Nasdaq:IDPH) today announced that it has begun a multi-center, Phase II clinical trial with the company's PRIMATIZED(R), non-depleting, anti-CD4 monoclonal antibody, Clenoliximab (IDEC-151). The double-blind, randomized, placebo-controlled study will evaluate the safety and clinical activity of multiple doses of the investigational agent when used in combination with methotrexate in patients with moderate to severe rheumatoid arthritis. Approximately 130 patients will be randomized to receive either IDEC-151 plus methotrexate or placebo plus methotrexate.

Clenoliximab targets the CD4 receptor on helper T cells, which are purported to play a key role in the pathogenesis of rheumatoid arthritis. Once bound to CD4, Clenoliximab is believed to regulate helper T-cell function, but without depleting T cells and affecting other important immune system functions.

"Clenoliximab is directed against a key target in rheumatoid arthritis and is therefore a potentially important new therapeutic agent," said Mark Totoritis, M.D., Senior Director, Autoimmune and Inflammatory Diseases. "Previous studies with this investigational agent provided preliminary evidence of clinical activity with respect to the primary endpoint of ACR 20 response rates. When studied as a single agent, up to approximately 60% of patients achieved such responses after a relatively brief course of therapy."

IDEC Pharmaceuticals focuses on the commercialization and development of targeted therapies for the treatment of cancer and autoimmune diseases. IDEC's antibody products act chiefly through immune system mechanisms, exerting their effect by binding to specific, readily targeted immune cells in the patient's blood or lymphatic systems.

IDEC Pharmaceuticals' news releases are available at no charge through Business Wire's News on Demand Plus. For a menu of IDEC's current news releases and quarterly reports or to retrieve a specific release, call [phone]. On the Internet check the News Center at IDEC's website: http://www.idecpharm.com.

The statements made in this press release contain certain forward-looking statements that involve a number of risks and uncertainties. Actual events or results may differ from IDEC's expectations. For example, the timing, success and cost of preclinical research and clinical studies, the timing, acceptability and review periods for regulatory filings, the timing of and ability to obtain regulatory approval of products and the risk factors listed from time to time in IDEC's SEC filings including but not limited to its Annual Report on Form 10-K for the year ended December 31, 1999 and Form 10-Q for the quarter ended March 31, 2000, may affect the actual results achieved by IDEC. These forward-looking statements represent the company's judgment as of the date of this release. The company disclaims, however, any intent or obligation to update these forward-looking statements.

IDEC Pharmaceuticals and PRIMATIZED are registered U.S. trademarks of the company. The company's headquarters is located at 3030 Callan Road, San Diego, CA 92121.