Phase 3b Study to Assess the Efficacy, Safety, and Tolerability of Remibrutinib in Comparison to Placebo, With Omalizumab as Active Control, in Adult CSU Patients, Followed by an Open-label 52-week Optional Extension.

Inclusion Criteria: * Male and female adult participants ≥18 years of age at the time of signing the informed consent. * CSU duration for ≥ 6 months prior to screening. * Diagnosis of CSU inadequately controlled by second generation H1-AH at the time of randomization, defined as: * The presence of itch and hives for ≥6 consecutive weeks prior to screening, despite the use of second-generation H1-AH during this time period. * UAS7 score (range 0-42) ≥16, ISS7 score (range 0-21) ≥ 6 and HSS7 score (range 0- 21) ≥ 6 during the 7 days prior to randomization (Day 1). * Documentation of hives within three months before randomization. * Willing and able to complete an Urticaria Patient Daily Diary (UPDD) for the duration of the study and adhere to the study protocol. * Participants must not have had more than one missing UPDD entry (either morning or evening) in the 7 days prior to randomization (Day 1). Exclusion Criteria: * Prior exposure to ligelizumab, omalizumab and other biologics with any effect in CSU, including anti-IgE therapies. * Significant bleeding risk or coagulation disorders. * History of gastrointestinal bleeding. * Requirement for anti-platelet or anti-coagulant medication. * History or current hepatic disease. * Evidence of clinically significant cardiovascular, neurological, psychiatric, pulmonary, renal, hepatic, endocrine, metabolic, hematological disorders, gastrointestinal disease or immunodeficiency that, in the investigator's opinion, would compromise t…