Vertex VX-509 12-week Phase 2a study on RA meets two primary endpoints

Vertex Pharmaceuticals Incorporated (Nasdaq: VRTX) today announced that treatment with the investigational selective oral JAK3 inhibitor VX-509 in a Phase 2a trial resulted in substantial and statistically significant improvements in multiple measurements of rheumatoid arthritis (RA) activity. The 12-week study met its two primary endpoints, defined as a statistically significant improvement in the proportion of people who achieved at least a 20 percent improvement in the signs and symptoms of RA, also known as ACR₂₀, and a statistically significant improvement from baseline in Disease Activity Score 28 (DAS28).

The study evaluated four doses of VX-509, and data from the treatment arms of the two highest doses (100 mg and 150 mg) showed statistically significant ACR₂₀, ACR₅₀, ACR₇₀ and DAS28 responses as compared to placebo. The 150 mg treatment arm showed ACR₂₀, ACR₅₀, ACR₇₀ and DAS28 responses of 66 percent, 49 percent, 22 percent and -3.06, respectively, while the placebo arm showed responses of 29 percent, 7 percent, 2 percent and -1.25. Overall, the most frequently reported class of adverse event in the VX-509 and placebo arms was infections. The most common individual adverse events observed, which occurred in approximately five percent or less of people in the study, were nausea, headache and increased alanine transaminase (ALT), regardless of treatment arm. Five percent of people discontinued treatment due to adverse events in the placebo group, compared to 8 percent of all people who received VX-509.

"These early results are encouraging and provide strong support that the selective targeting of JAK3 by VX-509 may represent a new approach to the treatment of RA and other autoimmune and inflammatory diseases," said Peter Mueller, Ph.D., Executive Vice President, Global Research and Development, and Chief Scientific Officer for Vertex. "In people who received VX-509, the signs and symptoms of RA continued to improve throughout the 12-week study. We look forward to initiating a longer-duration trial to explore the potential for additional improvements in RA activity and to further establish the safety profile of VX-509."

Data from this study will be submitted for presentation at an upcoming medical meeting. Based on the results announced today, VX-509 will next be evaluated as part of a six-month Phase 2b study in RA. This study is expected to evaluate once-daily (QD) and twice-daily (BID) doses of VX-509 in combination with methotrexate, a commonly prescribed disease-modifying antirheumatic drug (DMARD) for RA that is frequently used in combination with other RA medicines.