A Study to Evaluate Efficacy, Safety and Tolerability of Remibrutinib in Adult Participants With Severe Chronic Pruritus of Unknown Origin (CPUO)

This is a global, phase 3 multicenter, randomized, double-blind, placebo-controlled, parallel group study to evaluate the efficacy, safety, and tolerability of remibrutinib in adult participants with severe CPUO. The design includes 4 periods, for a total duration of up to 60 weeks: * Screening period: up to 4 weeks. * Double-blind treatment period (treatment period 1, TP1): 24 weeks of double-blind treatment with remibrutinib or matching placebo * Open-label treatment period (treatment period 2, TP2): 28 weeks of open-label treatment with remibrutinib. The participants randomized to the placebo arm will be switched to remibrutinib at Week 24. * Safety follow-up period: 4 weeks of treatment-free safety follow-up.