A Phase 3 Study of Efficacy and Safety of Remibrutinib in the Treatment of CSU in Adults Inadequately Controlled by H1-antihistamines

The study consisted of four periods, the total study duration was up to 60 weeks: Screening period of up to 4 weeks, Double-blind placebo-controlled treatment period of 24 weeks, Open-label treatment period with Remibrutinib period of 28 weeks, and treatment free follow-up period of 4 weeks. The design of this study was a replicate of another Phase III study, CLOU046A2301 (NCT05030311). The study population consisted of female and male adult patients with CSU inadequately controlled by second generation H1-AHs at least at a locally label approved dose. All patients were on a stable, locally label approved dose of a second generation H1 AH (background therapy) throughout the entire study (starting a minimum of 7 days prior to randomization until the end of the study). To treat unbearable symptoms of CSU, patients were allowed to use another second generation H1-AH on an as-needed basis (rescue therapy). Eligible patients were randomly assigned to the treatment arms in a 2:1 ratio to remibrutinib or placebo arm (300 in the remibrutinib arm and 150 in placebo arm) and stratified based on prior exposure to anti-IgE biologics for CSU and geographic region. An extension Phase IIIb study, CLOU064A2303B (NCT05513001), was initiated to allow CLOU064A2302 eligible patients to roll over after completion of the open-label treatment period. There were two distinct testing strategies (scenario 1 with Weekly Urticaria Activity Score (UAS7) as the primary efficacy endpoint and scenario 2 with Weekly Itch Severity Score (ISS7) and Weekly Hives Severity Score (HSS7) as the co-primary efficacy endpoints) based on two primary objective scenarios related to regional regulatory precedent and Health Authorities' feedback.