Efficacy and safety of low-dose tacrolimus for active rheumatoid arthritis with an inadequate response to methotrexate

Background/Aims: To determine the efficacy and safety of low-dose tacrolimus in Korean rheumatoid arthritis (RA) subjects with an inadequate response to methotrexate (MTX). Methods: This was a multicenter, open-label study conducted at five Korean sites. Fifty-six patients with active RA, despite treatment for ${\geq}1month$ with a stable, maximally tolerated dosage of oral MTX (median dosage, 15 mg/wk), were enrolled and received 1.5 mg/day of tacrolimus as a single oral dose once per day for 16 weeks while continuing to receive MTX. All other disease-modifying anti-rheumatic drugs were discontinued, whereas stable dosages of nonsteroidal anti-inflammatory drugs and oral corticosteroids (${\leq}10mg/day$ of prednisone or an equivalent corticosteroid) were allowed. The primary clinical response criterion was the American College of Rheumatology's definition of 20% improvement (ACR20) at the end of treatment. Results: The ACR20 response rate was 42.9% (24 of 56 patients) in patients who had received tacrolimus at least once. The overall ACR50 and ACR70 responses at the end of treatment for all patients were 30.4% and 10.7%, respectively. Throughout the treatment period, 37 patients experienced 71 adverse events (AEs) in total, and four patients left the study because of AEs. In addition, 15 patients in total experienced treatment-related AEs. Throughout the treatment period, two patients were reported to experience two serious AEs, and one patient left the study because of a serious AE. Conclusions: In patients whose active RA persists despite treatment with MTX, low-dose tacrolimus in combination with MTX appears to be safe and well tolerated, and provides clinical benefit.