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 the safety of the participant, interfere with the interpretation of the study results or otherwise preclude participation or protocol adherence of the participant. * Evidence of helminthic parasitic infection as evidenced by stools being positive for a pathogenic organism according to local guidelines. * Documented history of anaphylaxis. * Pregnant or nursing (lactating) women.