Rapid Onset of Response in Adults with Dermatomyositis Receiving Dazukibart: A Phase 2, Double-Blind, Randomized,...

Interferon-β (IFNβ) dysregulation contributes to dermatomyositis (DM) pathogenesis. In a previously published phase 2 study, 12-week treatment with dazukibart, an anti-IFNβ monoclonal antibody, reduced disease activity in moderate-to-severe DM. This prespecified secondary analysis evaluated the rapidity of onset of efficacy of dazukibart in DM at time points before Week 12, which may inform treatment decisions.

This is a secondary analysis of a double-blind, randomized, placebo-controlled phase 2 study (NCT03181893). Adults with skin-predominant (SP) or muscle-predominant (MP) DM received placebo or dazukibart (150 mg/600 mg) at baseline and every 4 weeks. Efficacy outcomes assessed at Weeks 1, 4, and 8 included: SP cohort-change from baseline (CFB) in Cutaneous Dermatomyositis Disease Area and Severity Index activity (CDASI-A), 5D-itch, and Dermatology Quality of Life Index (DLQI) and proportion of patients achieving ≥40% decrease in CDASI-A; MP cohort-Mean Total Improvement Score (TIS), CFB in myositis core set measures, and TIS response.

In SP cohort (n=57), statistically significant improvement was observed with dazukibart in mean CFB (placebo-adjusted difference) CDASI-A (Week 4; 150 mg: -10.5 [p=0.0006]; 600 mg: -9.7 [p=0.0004]), 5D-itch (Week 1; 600 mg: -2.0 [p=0.0359]), and DLQI (Week 4; 150 mg: -2.8 [p=0.0249]; 600 mg: -2.7 [p=0.0160]). CDASI-A score decreased by ≥40% in 53.3% (dazukibart 150 mg), 42.9% (dazukibart 600 mg), and 7.7% (placebo) patients at Week 4. In MP cohort (n=18), numerical improvements (sample size not powered to detect statistical significance) with dazukibart 600 mg vs placebo in mean TIS (Week 4) and statistically significant improvements in mean CFB creatine kinase levels (Week 4; p=0.0445) and Patient Global Assessment (Week 8; p=0.0470) were observed. At Week 4, 77.8% and 22.2% (dazukibart 600 mg) vs 66.7% and 0 (placebo) patients achieved minimal and major improvement, respectively.

Dazukibart induced rapid improvement in key skin- and muscle-related efficacy outcomes of disease activity in patients with DM. The small sample size of the MP cohort warrants a well-powered Phase 3 study to confirm these Phase 2 proof-of-concept results.

NCT03181893.