Phase 2 randomized, dose-ranging trial of CTP-543, a selective Janus Kinase inhibitor, in moderate-to-severe alopecia areata.

Background: Janus kinase (JAK) activation is suggested to have a pathological role in alopecia areata (AA). CTP-543, a deuterated compound that selectively inhibits JAK1 and JAK2, is being developed as an oral treatment for AA.

Objective: To assess the safety and efficacy of a 24-week regimen of CTP-543 in patients with chronic, moderate-to-severe AA.

Methods: In this phase 2, randomized, double-blind, placebo-controlled, sequential-design trial, patients were randomized to receive CTP-543 (4 mg, 8 mg, or 12 mg) or placebo every 12 hours for 24 weeks.

Results: A dose-related increase was observed in the percentage of patients with ≥50% relative reduction in Severity of Alopecia Tool scores from baseline at week 24 (9% placebo, 21% 4 mg twice daily, 47% 8 mg twice daily, and 58% 12 mg twice daily), with statistical significance versus placebo (P < .001) observed for the 8-mg twice daily and 12-mg twice daily groups, with differences from placebo noted as early as 12 weeks after the initiation of treatment. Safety results were consistent with the known safety profiles of JAK inhibitors.

Limitations: These initial findings are from a relatively small controlled trial, and additional studies are needed to fully characterize the safety and efficacy of CTP-543 in adult patients with AA.

Conclusions: Patients treated with CTP-543 (8 or 12 mg, twice daily) had a significant reduction in the severity of AA.