Study duration per participant will be up to 44 weeks (Study A) and 32 weeks (Study B).
The main objective of the study is to assess efficacy and safety of dupilumab given up to 24 weeks in adults with CPUO.~This is a master protocol which includes 2 parallel-treatment, double-blind, 2- arm Phase 3 staggered studies of similar design (Study A and Study B) in male and female participants aged 18 to 90 years with CPUO. Study B design may be adapted based on the results of Study A.~For both Study A and B, after an up-to-4-week screening period, participants with severe pruritus (worst-itch numerical rating scale [WI-NRS ≥7) will enter a 4-week run-in period during with a non-sedative antihistamine and an emollient (moisturizer). Participants with severe pruritus (WI-NRS ≥7) at baseline will be randomized (1:1) to be treated for 24 weeks (Study A) or 12 weeks (Study B) with either dupilumab or matching placebo in addition to their antihistamine and emollient regimen. The treatment period for both study A and B will be followed by a 12-week follow-up period.