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.

This study is looking for adult men and women, aged 18 or older. To be considered, you must have had chronic spontaneous urticaria (CSU) for at least six months. This means you've had persistent itchy hives for six weeks or more, even while taking a standard allergy medicine (a second-generation H1-antihistamine).

Your CSU symptoms, including itching and hives, need to be at a certain level to qualify for the study. Researchers will use special scoring systems to measure your symptoms in the days leading up to starting the study. You also need to be willing and able to fill out a daily diary about your symptoms throughout the study.

There are also some reasons why you might not be able to join. For example, if you've previously taken certain other specific medicines for CSU (like omalizumab or ligelizumab), or if you have certain other medical conditions such as serious bleeding problems, stomach or liver issues, or active infections. The study is also not suitable if you are pregnant or breastfeeding.

If you join this study, it could last up to about two years. It starts with a four-week screening period to check if you're suitable. Once confirmed, you'll enter the main treatment phase, which lasts for 52 weeks (about a year). During this time, you’ll take a study medicine, which could be remibrutinib, omalizumab, or a dummy treatment (placebo). You won't know which one you're getting, and neither will your study doctor, to ensure fair results. You'll also continue taking your usual allergy medicine (antihistamine) throughout this phase.

After the first year, you might have the option to join an extension phase, where you would receive remibrutinib for another 52 weeks. Throughout the study, you'll have regular visits to the clinic for assessments and to check your health. You'll also be asked to complete a daily diary about your symptoms. If your symptoms become very challenging at any point, you'll also be allowed to take an extra allergy medicine as a 'rescue' treatment. At the end of your study participation, there will be a follow-up period of 4 to 16 weeks to check on your health after stopping the study medication.