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

Inclusion Criteria:

1. Signed informed consent must be obtained prior to participation in the study.
2. Male and female participants ≥18 years of age.
3. CSU duration for ≥ 6 months prior to screening (defined as the onset of CSU determined by the investigator based on all available supporting documentation).

Diagnosis of CSU inadequately controlled by second generation H1-antihistamines at baseline defined as:

1. The presence of itch and hives for ≥ 6 consecutive weeks prior to screening despite the use of second generation H1-antihistamines during this time period
2. 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 baseline (Day 1)
3. Documentation of hives within three months before baseline (either at screening and/or at baseline; or documented in the participants' medical history).
4. Willing and able to complete an Urticaria Patient Daily Diary (UPDD) for the duration of the study and adhere to the study protocol
5. Participants must not have had more than one missing UPDD entry (either morning or evening) in the 7 days prior to baseline (Day 1).

Exclusion Criteria:

1. Participants having a clearly defined predominant or sole trigger of their chronic urticaria (chronic inducible urticaria) including urticaria factitia (symptomatic dermographism), cold-, heat-, solar-, pressure-, delayed pressure-, aquagenic-, cholinergic-, or contact-urticaria
2. Other diseases with symptoms of urticaria or angioedema, including but not limited to urticaria vasculitis, urticaria pigmentosa, erythema multiforme, mastocytosis, hereditary urticaria, or drug-induced urticaria
3. Any other skin disease associated with chronic itching that might influence in the investigator's opinion the study evaluations and results, e.g., atopic dermatitis, bullous pemphigoid, dermatitis herpetiformis, senile pruritus or psoriasis
4. Evidence of clinically significant cardiovascular (such as but not limited to myocardial infarction, unstable ischemic heart disease, New York heart association (NYHA) Class III/IV left ventricular failure, arrhythmia and uncontrolled hypertension within 12 months prior to Visit 1), 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
5. Significant bleeding risk or coagulation disorders
6. History of gastrointestinal bleeding, e.g., in association with use of nonsteroidal anti- nflammatory drugs (NSAID), that was clinically relevant (e.g., requiring hospitalization or blood transfusion)
7. Requirement for anti-platelet medication, except for acetylsalicylic acid up to 100 mg/d or clopidogrel. The use of dual anti-platelet therapy (e.g., acetylsalicylic acid + clopidogrel) is prohibited.
8. Requirement for anticoagulant medication (for example, warfarin or Novel Oral Anti-Coagulants (NOAC))
9. History or current hepatic disease including but not limited to acute or chronic hepatitis, cirrhosis or hepatic failure or Aspartate Aminotransferase (AST)/ Alanine Aminotransferase (ALT) levels of more than 1.5 x upper limit of normal (ULN) or International Normalized Ratio (INR) of more than 1.5 at screening