Inhibition of Spleen Tyrosine Kinase for Rheumatoid Arthritis

Introduction: Spleen tyrosine kinase (Syk) is an important mediator of immunoreceptor signaling in macrophages, neutrophils, mast cells, and B cells. It is found on the synovium of rheumatoid arthritis (RA) patients, suggesting a role for Syk inhibition in the treatment of RA. In an earlier study, the Syk inhibitor R788 was administered for 12 weeks to a refractory RA population not responsive to methotrexate (MTX). Significant reductions in arthritis and serum levels of interleukin-6 were observed in those who received R788 as compared with placebo [1].