This clinical trial is focused on studying a condition known as Chronic Spontaneous Urticaria (CSU), which is characterized by the sudden appearance of hives and itching without a known cause. The study aims to evaluate the effectiveness, safety, and tolerability of a medication called remibrutinib, which is taken as a 25 mg film-coated tablet. Remibrutinib works by inhibiting a specific enzyme in the body that is involved in the immune response. The study will compare remibrutinib to a placebo and to another medication called omalizumab, which is given as an injection every four weeks. Omalizumab is already used as a treatment for CSU and will serve as an active control in this study.

The purpose of the study is to determine if remibrutinib is more effective than a placebo in reducing the symptoms of CSU, such as itching and hives, over a period of 52 weeks. Participants in the study will be randomly assigned to receive either remibrutinib, a placebo, or omalizumab. The study is designed to be double-blind, meaning neither the participants nor the researchers will know who is receiving which treatment, to ensure unbiased results. Throughout the study, participants will be monitored for any changes in their symptoms and any side effects they may experience.

This trial is important for understanding how well remibrutinib works in treating CSU, especially in patients who have not responded well to other treatments like second-generation H1-antihistamines. The study will help determine if remibrutinib can provide a new option for managing this challenging condition. Participants will be required to keep a daily diary of their symptoms to help researchers assess the effectiveness of the treatment. The study will last for a total of 52 weeks, with regular check-ins to monitor progress and any potential side effects.