Concomitant Iguratimod Therapy in Patients with Active Rheumatoid Arthritis Despite Stable Doses of Methotrexate: a Randomized, Double-blind, Placebo-controlled Trial

Objectives: To investigate the efficacy and safety of iguratimod (T-614) in Japanese patients with active rheumatoid arthritis who had inadequate response to stable background methotrexate (MTX) alone.

Methods: In this multicenter, double-blind, controlled trial, a total of 253 patients were randomized at 2:1 ratio to either the iguratimod group or the placebo group. Iguratimod was orally administered at dosages of 25 mg/day for the first 4 weeks (25 mg once daily) and 50 mg/day for the subsequent 20 weeks (25 mg twice daily). MTX at dosage of 6 or 8 mg/week was administered to patients in both groups.

Results: The rate of 20 % improvement in American College of Rheumatology criteria (ACR20) at week 24 was 69.5 % in the iguratimod group compared with 30.7 % in the placebo group (P < 0.001). Significant improvements in the ACR50, ACR70, Health Assessment Questionnaire Disability Index, Disease Activity Score 28 <3.2, and rheumatoid factor were also observed. The most commonly reported adverse events (AEs) were blood iron decrease, nasopharyngitis, and lymphocyte decrease. These AEs were mild or moderate in severity. No deaths occurred.

Conclusion: The study results suggest that iguratimod in combination with MTX was efficacious and had a manageable safety profile.