Objective: To evaluate the efficacy and safety of tacrolimus as monotherapy in controlling the signs and symptoms of patients with rheumatoid arthritis (RA).
Methods: This was a 6-month, phase III, double-blind, multicenter study. Patients with active RA who had discontinued all disease-modifying antirheumatic drugs (DMARDs) for an appropriate washout period (at least 1 month) and who, after the washout period, had a stable joint count (at least 10 tender/painful joints and 7 swollen joints) were stratified according to DMARD intolerance or DMARD resistance, and randomized to receive a single daily oral dose of placebo, tacrolimus 2 mg, or tacrolimus 3 mg.
Results: A total of 464 patients received at least 1 dose of study drug. Baseline characteristics were similar among the 3 treatment groups. American College of Rheumatology 20% improvement (ACR20) success (defined as completion of 6 months of treatment and an ACR20 response at the month 6 visit) for the placebo, tacrolimus 2 mg, and tacrolimus 3 mg groups was 10.2%, 18.8% (P < 0.05 versus placebo), and 26.8% (P < 0.0005 versus placebo), respectively. At the end of treatment, the ACR20 and ACR50 response rates in the 3-mg group were 32.0% (P < 0.005 versus placebo) and 11.8% (P < 0.05 versus placebo), respectively. DMARD-intolerant patients had better ACR response rates than did DMARD-resistant patients. Although serum creatinine levels increased by >/=40% from baseline at some time during the trial in 20% and 29% of patients receiving tacrolimus 2 mg/day and 3 mg/day, respectively, the serum creatinine level remained within the normal range throughout the trial in approximately 90% of patients.
Conclusion: Tacrolimus, at dosages of both 2 mg/day and 3 mg/day, is efficacious and safe as monotherapy for patients with active RA, but treatment with the 3-mg dose of tacrolimus resulted in generally better ACR response rates.