Brepocitinib Phase 3 Trial Findings in Dermatomyositis

Key Takeaways

• Brepocitinib 30 mg was associated with a higher week-52 Total Improvement Score than placebo in adults with dermatomyositis.
• The 30-mg dose was also superior across all nine key secondary end points, with improvement observed by week 4.
• Serious infections were more frequent with brepocitinib 30 mg than with placebo, 10% versus 1%, and no deaths occurred.

In adults with active dermatomyositis, brepocitinib 30 mg improved the week-52 Total Improvement Score by 15.3 points versus placebo (95% CI, 6.7 to 24.0; P<0.001) in a phase 3 trial. The randomized, placebo-controlled trial tested two once-daily oral doses over 52 weeks in adults whose disease had remained resistant to previous therapy. Significant benefit was seen only with the higher dose.

The phase 3 trial was a double-blind, randomized, placebo-controlled study in 241 adults with dermatomyositis. Patients were assigned 1:1:1 to once-daily oral brepocitinib 30 mg, brepocitinib 15 mg, or placebo. Each active-treatment group included 81 participants, and 79 received placebo. Treatment continued for 52 weeks while standard therapies were maintained and glucocorticoids were tapered. The primary end point was the Total Improvement Score at week 52.

At week 52, mean Total Improvement Scores were 46.5 with brepocitinib 30 mg, 37.5 with brepocitinib 15 mg, and 31.2 with placebo. The 30-mg group had the highest average improvement among the three trial arms. For 15 mg versus placebo, the difference was 6.3 points (95% CI, -2.4 to 14.9), with the confidence interval crossing zero. The primary efficacy results therefore separated 30 mg, but not 15 mg, from placebo.

The broader efficacy pattern also favored the higher dose. Brepocitinib 30 mg was superior to placebo across all nine key secondary end points, including skin disease activity, glucocorticoid tapering, and functional disability. Improvement was observed as early as week 4. Significant benefits with 30 mg, but not 15 mg, extended across the composite myositis index and those clinical domains.

Safety findings showed more serious infections at the higher dose. Serious infections occurred in 10% of patients receiving brepocitinib 30 mg and 1% of those receiving placebo. No deaths occurred during the trial.