Rigel's R788 Drug Improves RA Symptoms

(Updates stock price)

Rigel Pharmaceuticals(RIGL Quote) said Thursday that its oral medicine, R788, significantly improved the symptoms of rheumatoid arthritis patients in a phase II study compared with a placebo, but as in previous studies of the drug high blood pressure emerged as a leading side effect.

Based on these new R788 data, the South San Francisco-based drugmaker said it will seek out a corporate partner to co-develop and help finance phase III studies of R788 beginning in the first half of next year.

Rigel's R788 is one of two oral drugs in mid- and late-stage clinical trials as a treatment for rheumatoid arthritis, or RA, a progressive disease in which a patient's own immune system attacks the bones and cartilage in the body's joints.

The current RA treatment market totals about $14 billion in sales worldwide, with the bulk of that coming from a class of injectable drugs known as "TNF-alpha inhibitors."

Rigel and Pfizer(PFE Quote) are locked in a race to develop the first oral pill for RA that could compete, perhaps even supplant, the current dominance of these TNF-alpha inhibitor drugs -- mainly Johnson & Johnson's(JNJ Quote) Remicade; Enbrel, which is sold by Amgen(AMGN Quote) and Wyeth(WYE Quote); and Abbott Labs'(ABT Quote) Humira.

Rigel's phase II study, known as Taski2, enrolled 457 patients with RA who were treated with one of two doses of R788 or a placebo for six months. Of the patients treated with 100 mg of R788 twice a day, 66% demonstrated a so-called ACR20 score, which means their RA symptoms improved by 20%. By comparison, only 35% of patients treated with a placebo improved enough to score an ACR20 response.