Remibrutinib Showed a Favorable Safety Profile and Sustained Efficacy in Japanese Patients with Chronic Spontaneous Urticaria Over 52 Weeks

Introduction: Remibrutinib, an oral, highly selective, Bruton’s tyrosine kinase (BTK) inhibitor, has shown efficacy and favorable safety in pivotal global phase 3 studies in patients with chronic spontaneous urticaria (CSU). This 52-week safety study evaluated the effect of remibrutinib in Japanese patients with CSU. Methods: BISCUIT, a phase 3 (NCT05048342), open-label, single-arm study, investigated the safety and efficacy of remibrutinib 25 mg twice-daily as an add-on medication in Japanese patients with CSU who remain symptomatic despite treatment with H₁-antihistamines. The primary endpoint was the proportion of patients with ≥ 1 adverse events (AEs). Results: Overall, 71 Japanese patients (mean age 43.5 years) had a median remibrutinib exposure of 52.1 weeks; 87.3% of patients reported ≥ 1 AE, and all events were mild or moderate in severity. COVID-19 (19.7%) and headache (12.7%) were the most common AEs. Three serious AEs, unrelated to remibrutinib, were reported. No deaths occurred during the treatment period. At week 12, mean change from baseline in weekly Urticaria Activity Score (UAS7) and weekly Itch/Hives Severity Scores was − 18.1, − 8.0, and − 10.1, respectively; responses appeared to occur as early as week 1 and appeared to be sustained until week 52. Additionally, 53.6% of the patients had well-controlled disease (UAS7 ≤ 6) and 30.4% had complete absence of itch and hives (UAS7 = 0) at week 52. Conclusion: Remibrutinib showed a favorable safety profile and a meaningful improvement in CSU symptoms (itch and hives) at week 12, with fast improvement as early as week 1 that was sustained up to week 52, supporting its potential as an effective oral BTK inhibitor for Japanese patients with CSU. Trial Registration: Trial Registration: NCT05048342.