New Rheumatoid Arthritis Drug Succeeds in Trial

Vertex Pharmaceuticals, Inc. announced positive results yesterday from a Phase 2a trial of its investigational oral JAK3 inhibitor VX-509 for rheumatoid arthritis (RA). The new rheumatoid arthritis drug is designed to work by selectively inhibiting Janus kinase 3 (JAK3), a key part of the signaling cascade that helps lead to the abnormal immune response found in those suffering from RA.

The 12-week study on the new rheumatoid arthritis drug reached its two primary endpoints in showing significantly better performance than placebo in terms of the portion of patients who experienced at least a 20% improvement in signs and symptoms of RA (known as ACR20) as well as a statistically significant improvement from baseline in Disease Activity Score 28 (DAS28).

The study looked at the effects of four dosing levels of VX-509 and found that the two highest doses (100 mg twice daily and 150 mg twice daily) demonstrated significantly better results in terms of ACR20, ACR50, ACR70, and DAS28 compared with placebo.

The 150 mg dose yielded an ACR20 of 66%, ACR50 of 49%, ACR70 of 22%, and DAS28 of -3.06. The corresponding results for the 100 mg dose were 65%, 38%, 18%, and -2.70, and for the placebo were 29%, 7%, 2%, and -1.25. In the placebo group 5% of participants stopped treatment due to adverse events compared with 8% in the VX-509 group.

The study included 204 people at approximately 40 trial sites in the US and Europe with moderate to severe RA who had had inadequate response to at least one non-biologic, non-injectable disease-modifying antirheumatic drug. VX-509 will next be tested in a six-month Phase 2b study, which will most likely evaluate the medication in once-daily and twice-daily doses in conjunction with methotrexate.

Source

Phase 2a Study of Selective Oral JAK3 Inhibitor VX-509 Showed Significant Improvements in Signs and Symptoms of Rheumatoid Arthritis [Press Release]