A Study to Investigate Efficacy, Safety, and Tolerability of Remibrutinib Compared With Placebo in Adults With CINDU Inadequately Controlled by H1-antihistamines

This study consists of a core and extension periods. The Core period (6 arms) has a total duration of up to 60 weeks including a double-blind placebo-controlled treatment period until Week 24 followed by open-label treatment with remibrutinib up to Week 52. The primary endpoint for all CINDU subtypes is assessed at Week 12. The Core period consists of: * Screening period (up to 4 weeks): During the screening period, participants who have provided informed consent will be assessed for study eligibility. * Double-blind, placebo-controlled treatment period (24 weeks): 24 weeks of double-blind treatment with remibrutinib or placebo. * Open-label treatment period (28 weeks): 28 weeks of open-label treatment with remibrutinib. * Follow-up period: 4 weeks of treatment free follow-up. The open-label extension period consists of observation and treatment period. At the end of the core period of the study, if participants continue to experience symptoms, they will transition to the treatment period in OLE. If they do not experience symtpoms they will transition to the observation period in the OLE. The duration of the Open-label Extension period will be approximately 3 years where participants can switch from observation to treatment depending on if they start developing symptoms. Only those participants participating in the Open-label Extension Treatment period will receive remibrutinib. The participants in the Open-label Extension Observation period will not receive remibrutinib