Ritlecitinib for rheumatoid arthritis succeeds in phase II trial

Ritlecitinib, an oral JAK3/TEC inhibitor, appears to be well tolerated and produce significant improvements disease activity in patients with rheumatoid arthritis (RA), according to the results of a phase II study.

In total, 70 patients (average age, 55 years; 81.4 percent female) who were seropositive for anticitrullinated protein antibodies and/or rheumatoid factor were randomized to receive ritlecitinib 200 mg once daily (n=42) or placebo (n=28) for 8 weeks.

All patients had been receiving methotrexate at a mean dose of about 15.0 mg/week and continued this treatment throughout the study. Overall, 24.3 percent of patients were previously treated with a tumour necrosis factor inhibitor.

At week 8, the primary endpoint of change in the Simplified Disease Activity Index (SDAI) score from baseline was significantly greater in the active treatment than in the placebo group (−26.1 vs −16.8; p<0.001).

More patients on ritlecitinib vs placebo achieved low disease activity as defined by SDAI (23.8 percent vs 7.1 percent; p=0.042). There were no differences in rates of remission (7.1 percent vs 0 percent; p=0.072).

Median treatment duration was 57 days in both groups. The number of treatment-emergent adverse events (TEAEs) was numerically higher in the active treatment group. Most events were mild in severity, and there were no serious or severe TEAEs and deaths reported. The most common TEAEs were infections and infestations, and skin and subcutaneous tissue disorders. One patient on ritlecitinib developed a mild case of herpes simplex that was considered to be treatment-related; this was resolved within 3 days without treatment discontinuation or antiviral therapy.