The purpose of this study was to establish the efficacy, safety, and tolerability of Remibrutinib 25 mg b.i.d. in adult patients suffering from chronic spontaneous urticaria (CSU) inadequately controlled by second generation H1-antihistamines (H1-AHs) in comparison to placebo.

The study consisted of four periods, the total study duration was up to 60 weeks: Screening period of up to 4 weeks, Double-blind placebo-controlled treatment period of 24 weeks, Open-label treatment period with Remibrutinib period of 28 weeks, and treatment free follow-up period of 4 weeks.

The design of this study was a replicate of another Phase III study, CLOU046A2301 (NCT05030311).

The study population consisted of female and male adult patients with CSU inadequately controlled by second generation H1-AHs at least at a locally label approved dose. All patients were on a stable, locally label approved dose of a second generation H1 AH (background therapy) throughout the entire study (starting a minimum of 7 days prior to randomization until the end of the study). To treat unbearable symptoms of CSU, patients were allowed to use another second generation H1-AH on an as-needed basis (rescue therapy). Eligible patients were randomly assigned to the treatment arms in a 2:1 ratio to remibrutinib or placebo arm (300 in the remibrutinib arm and 150 in placebo arm) and stratified based on prior exposure to anti-IgE biologics for CSU and geographic region.

An extension Phase IIIb study, CLOU064A2303B (NCT05513001), was initiated to allow CLOU064A2302 eligible patients to roll over after completion of the open-label treatment period.

There were two distinct testing strategies (scenario 1 with Weekly Urticaria Activity Score (UAS7) as the primary efficacy endpoint and scenario 2 with Weekly Itch Severity Score (ISS7) and Weekly Hives Severity Score (HSS7) as the co-primary efficacy endpoints) based on two primary objective scenarios related to regional regulatory precedent and Health Authorities' feedback.

Key Inclusion Criteria:

• Signed informed consent must be obtained prior to participation in the study.

• Male and female adult participants >= 18 years of age at the time of screening.

• 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 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-antihistamines 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 (either at screening and/or at randomization; or documented in the participants medical history).

• 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).

Key Exclusion Criteria:

• Participants having a clearly defined predominant or sole trigger of their chronic urticaria (CU) (chronic inducible urticaria (CINDU)) including urticaria factitia (symptomatic dermographism), cold-, heat-, solar-, pressure-, delayed pressure-, aquagenic-, cholinergic-, or contact-urticaria
• 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
• 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
• 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
• Significant bleeding risk or coagulation disorders
• History of gastrointestinal bleeding, e.g. in association with use of nonsteroidal anti-inflammatory drugs (NSAID), that was clinically relevant (e.g. requiring hospitalization or blood transfusion)
• 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.
• Requirement for anticoagulant medication (for example, warfarin or Novel Oral Anti-Coagulants (NOAC))
• 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

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This trial data availability is according to the criteria and process described on www.clinicalstudydatarequest.com