Objective: To determine the efficacy and safety of pamapimod in adult patients with active rheumatoid arthritis (RA) who had an inadequate clinical response to methotrexate (MTX).
Methods Patients receiving stable doses of MTX were randomized to one of six dose groups and received 12 weeks of double-blind pamapimod (up to 300 mg once daily [qd]) or matching placebo. The primary efficacy measure was the proportion of patients with ≥ 20% improvement in RA based on the American College of Rheumatology criteria (ACR20) at 12 weeks. Secondary measures were ACR50, DAS/EULAR response, and individual ACR core set of parameters. Safety measures included adverse events (AEs), laboratory testing, and immunology assessments.
Results On a background of MTX, the percentage of patients with an ACR20 response at week 12 in the pamapimod groups (31-43%) was not significantly different from placebo (34%). Secondary efficacy end points showed a similar pattern. AEs were typically mild and included infections, gastrointestinal disturbances, dizziness and rashes; AEs resulting in discontinuation of study drug were primarily attributed to infections.
Conclusion: In patients with active RA receiving stable doses of MTX, pamapimod showed non-significant improvement in efficacy outcomes compared to placebo.