BackgroundWe investigated the efficacy and safety of dupilumab in Japanese patients aged ≥6 months to <18 years old with moderate-to-severe atopic dermatitis not adequately controlled with existing therapies. MethodsIn this randomized, double-blind, phase 3 study, patients received dupilumab (n = 30) or placebo (n = 32) with concomitant topical corticosteroids for 16 weeks, then all patients received dupilumab from 16 to 52 weeks. The primary endpoint was the proportion of patients with ≥75% improvement in Eczema Area and Severity Index (EASI) score from baseline (EASI-75) to Week 16. Key secondary endpoints included changes in EASI score, proportion of patients with investigator global assessment (IGA) scores of 0/1, and changes in worst daily itch numerical rating scale (NRS) scores (evaluated in patients aged ≥6 to <12 years [n = 35]). ResultsAt Week 16, more patients achieved EASI-75 with dupilumab than placebo (43.3% vs 18.8%; P = 0.0304), and the least squares mean (LSM) difference in percent change in EASI scores at Week 16 of dupilumab vs placebo was –39.4% (P = 0.0003). However, no significant difference in the proportion of patients achieving IGA scores of 0/1 at Week 16 with dupilumab versus placebo were seen (10.0% vs 9.4%; P = 0.8476). The percent change in worst daily itch NRS scores at Week 16 was higher with dupilumab (LSM difference: –33.3%; nominal P = 0.0117). Dupilumab was well tolerated; no new safety signals were identified. ConclusionsDupilumab showed consistent efficacy and was well tolerated in Japanese patients aged ≥6 months to <18 years with moderate-to-severe atopic dermatitis previously insufficiently controlled with existing therapies.