Study design
PRIME and PRIME2 were phase 3, randomized, placebo-controlled, double-blind, multicenter, parallel-group, 24-week trials designed to evaluate efficacy and safety of dupilumab in adults with PN inadequately controlled with topical prescription therapies. Patients were enrolled in 16 countries in North and South America, Europe and Asia, from 12 December 2019 to 3 February 2022 (PRIME) and 16 January 2020 to 22 November 2021 (PRIME2). Each study had a 2–4-week screening period, followed by a 24-week intervention period and a 12-week post-treatment follow-up period (Extended Data Fig. The PRIME and PRIME2 protocols were developed by the sponsors, Sanofi and Regeneron Pharmaceuticals Inc. (redacted protocols are provided in Supplementary Data 