Rigel Announces Initiation of Phase 1 Clinical Trial of R348 for Rheumatoid Arthritis, Psoriasis and Other Immune...( SOUTH SAN FRANCISCO Calif. Jan. 9...),Health

SOUTH SAN FRANCISCO, Calif., Jan. 9 /PRNewswire-FirstCall/ -- Rigel Pharmaceuticals, Inc. (Nasdaq: RIGL) announced today that it has begun enrolling patients in a Phase 1 study to evaluate the safety and tolerability of R348, an orally available, potent inhibitor of Janus Kinase 3 (JAK3), as a potential treatment for patients with rheumatoid arthritis (RA), psoriasis and other immune disorders. In preclinical studies, R348 was shown to be effective in reducing arthritic symptoms, bone destruction and swelling. It has also shown efficacy in models of psoriasis and transplant rejection. This is Rigel's fourth novel product candidate in clinical trials.

"R348 enters the clinic at a time when Rigel's product portfolio is demonstrating its potential contribution to the field of immunology," said Donald G. Payan, M.D., executive vice president and chief scientific officer at Rigel. "With R348 targeting T-cells and our oral syk kinase inhibitor, R788, targeting B-cells and other immune cells, Rigel has mounted a comprehensive assault on autoimmune disorders," he added.

This study will evaluate the safety and pharmacokinetics of R348 in young, healthy males using a double blind, placebo controlled, single dose and multiple rising doses of R348. Results are expected in mid-2008.

JAK3 in RA and Other Immune Disorders

RA affects approximately 1% of the population worldwide -- approximately 2.1 million Americans -- and is a debilitating and degenerative autoimmune disease. Psoriasis affects approximately 7.5 million in the U.S. and an estimated 125 million worldwide, and is a lifelong skin disease. About 10-30% of patients with psoriasis also develop psoriatic arthritis, which causes pain, swelling and stiffness of the joi
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