AstraZeneca's new oral Syk inhibitor, fostamatinib, recently in-licensed from Rigel Pharmaceuticals, Inc., significantly improved outcomes of patients with rheumatoid arthritis (RA) who responded inadequately to ongoing treatment with methotrexate, according to phase II study data published in The New England Journal of Medicine. In the 6-month phase IIb study, two-thirds of patients taking fostamatinib 100 mg twice daily achieved the primary efficacy end point (ACR 20), significantly higher results than placebo. After 1 week on the therapy, 36% of patients achieved an ACR 20, which may be significant since speed of onset in active RA can result in permanent joint damage. The most common adverse events included diarrhea and upper respiratory infection.
“In this study, we saw a significant clinical benefit in this rheumatoid arthritis population and a manageable safety profile,” said Mark C. Genovese, Division of Rheumatology, Stanford University. “Based on the data, further study of fostamatinib as an oral agent for the treatment of patients with rheumatoid arthritis is certainly warranted.”