Phase 2b study of JAK3 inhibitor VX-509 shows improvement in people with active RA

Vertex Pharmaceuticals Incorporated (Nasdaq: VRTX) today announced 12-week results from an ongoing Phase 2b study of VX-509, an investigational oral, selective Janus kinase 3 (JAK3) inhibitor, dosed once or twice daily in people with active rheumatoid arthritis (RA) taking methotrexate. The study met its primary endpoints of both the proportion of people who achieved at least a 20 percent improvement in signs and symptoms of RA, as measured by the ACR improvement criteria (ACR20), and the change from baseline in Disease Activity Score for 28 joints (DAS28). All doses of VX-509 showed statistically significant ACR20 and ACR50 responses versus placebo and statistically significant improvement from baseline in DAS28 versus placebo. The three highest dose groups showed ACR20 responses of between 58 percent and 68 percent, compared to 18 percent for placebo, and statistically significant ACR70 responses versus placebo.

In the study, the discontinuation rate due to adverse events was 6.6 percent for the pooled VX-509 treatment group and 8.5 percent for the placebo group. Overall, adverse event rates were 51.2 percent in the pooled VX-509 treatment groups compared to 38.0 percent for those who received placebo, and the majority of adverse events observed in the study were mild to moderate.

The results were published online today as part of a late-breaker abstract accepted for an oral presentation at the American College of Rheumatology (ACR) annual meeting. The study is ongoing, and Vertex expects 24-week data to be available in early 2014.

"These results are encouraging and provide further support for the development of VX-509 as a new approach to treating RA and potentially other immune-mediated and inflammatory diseases by selectively targeting JAK3," said Robert Kauffman, M.D. Ph.D., Senior Vice President and Chief Medical Officer at Vertex. "In this study, treatment with VX-509 showed good tolerability and resulted in significant improvements in the signs and symptoms of RA across all doses tested. We look forward to the presentation of these data at the ACR annual meeting later this month."

Source: Vertex Pharmaceuticals Incorporated