Nemolizumab With Concomitant Topical Therapy in Adolescents and Adults With Moderate-to-Severe Atopic Dermatitis (ARCADIA 1 and ARCADIA 2): Results From Two Replicate, Double-Blind, Randomized Controlled Phase 3 Trials

To evaluate the efficacy and safety of nemolizumab, an interleukin (IL)-31 receptor antagonist, added to topical therapy over a 16-week period in adults and adolescents with moderate to severe atopic dermatitis that was not adequately controlled by topical treatments alone.Two identical trials, ARCADIA 1 and ARCADIA 2, enrolled a total of 1728 individuals. Participants were aged 12 years or older with a diagnosis of moderate to severe atopic dermatitis, associated pruritus, and inadequate response to topical steroid therapy.Two identical randomized phase 3 trials evaluated nemolizumab over 48 weeks. This report summarizes the initial 16-week double-blind, placebo-controlled period. Participants were randomized 2:1 to receive subcutaneous nemolizumab 30 mg (after a 60-mg loading dose) or placebo every 4 weeks. All continued background topical corticosteroids, with or without calcineurin inhibitors. Co–primary endpoints at week 16 were Investigator’s Global Assessment (IGA) success (score of 0 or 1 with ≥2-point improvement) and greater than or equal to 75% improvement in Eczema Area and Severity Index (EASI-75).A significantly higher proportion of participants in the nemolizumab groups met the co–primary endpoints compared with the placebo groups in both studies. For IGA success, the rates were 36% (nemolizumab) vs 25% (placebo) in ARCADIA 1 and 38% vs 26% in ARCADIA 2. For EASI-75 response, the rates were 44% (nemolizumab) vs 29% (placebo) in ARCADIA 1 and 42% vs 30% in ARCADIA 2. Nemolizumab also provided significant improvements in all key secondary endpoints, including itch relief starting as early as week 1 and sleep improvement by week 16. The overall safety profile was similar between the treatment and placebo groups, with most adverse events being nonserious and mild or moderate in severity. The most common treatment-emergent adverse event was worsening of atopic dermatitis, which occurred at similar rates in all groups.Nemolizumab added to background topical therapy was efficacious, showing statistically and clinically significant improvements in both skin inflammation and pruritus in adults and adolescents with moderate to severe atopic dermatitis. The treatment demonstrated a rapid effect in reducing pruritus, a primary treatment target for patients. Nemolizumab could be a valuable addition to current therapies for this condition.These 2 large, well-designed, phase 3 trials provide strong evidence for the efficacy of nemolizumab in treating moderate to severe atopic dermatitis. The study demonstrated significant improvements in both skin inflammation and pruritus. The rapid itch reduction is a particularly important finding given that pruritus is a primary driver of morbidity in this disease. The safety profile was comparable to placebo. Although these results cover the initial 16-week treatment period, the study’s design includes a 32-week extension that will provide crucial data on sustained efficacy and safety in the future. Overall, these findings strongly support targeting the IL-31 pathway as a key therapeutic strategy for atopic dermatitis.