Study design
This was a multicentre, double-blind, placebo-controlled, randomised, parallel-group study conducted at 47 sites in Japan (NCT03605251, JapicCTI-184020). The study consisted of two parts: part A, in which patients received TAS5315 4 or 2 mg or placebo for 12 weeks; and part B, in which patients in the TAS5315 groups continued at the same dose, and those in the placebo group were switched to TAS5315 4 or 2 mg, for another 24 weeks (
The primary objective was to examine the efficacy of TAS5315 in combination with MTX after 12 weeks of treatment in patients with active RA who had inadequate responses to MTX.