VX-509 (decernotinib) is a novel oral, selective inhibitor of JAK-3. JAK-3 is a member of the JAK signalling family that is primarily expressed in hematopoietic cells and associates with only the common γ-chain making it a promising therapeutic drug target. A phase IIb 24-week study of VX-509 in 358 patients with RA, who had prior inadequate response to MTX, uses ACR20 response rate and DAS28-CRP change at Week 12 to assess the efficacy of VX-509. Patients were administered either placebo+MTX or...