Clinical Trial Shows Results for Rheumatoid Arthritis Drug

(National Institutes of Health)

A six-month clinical trial of the drug fostamatinib, developed by Rigel Pharmaceuticals of South San Francisco, California, shows improved outcomes for patients with rheumatoid arthritis (RA) who responded inadequately to ongoing treatment with another RA drug, methotrexate. Fostamatinib is an inhibitor of spleen tyrosine kinase, a modulator of immune signaling.

The double-blind, placebo-controlled phase 2 trial covered 457 patients suffering from RA despite long-term methotrexate therapy. The outcome target was the American College of Rheumatology (ACR) 20 response, which indicates at least a 20 percent reduction in the number of both tender and swollen joints and improvement in at least three of five other criteria after six months.

In the trial, two-thirds (67%) of the patients taking 100 mg of fostamatinib twice daily achieved the primary ACR 20 target at six months, which was significantly higher than placebo. Some 36 percent of patients achieved an ACR 20 response after just one week. Rigel says speed of onset may be an important factor in RA because permanent joint damage can occur when the disease is active. The most common adverse events included diarrhea and upper respiratory infection.

The findings were published online in the New England Journal of Medicine. Rigel has licensed the drug to AstraZeneca that plans to begin a phase 3 trial soon on larger numbers of subjects with more variables.