Remibrutinib Reduces CSU Symptoms Within 12 Hours in Phase 3 REMIX Analysis

Pooled data from the phase 3 REMIX-1 and REMIX-2 trials suggest that remibrutinib may reduce daily disease activity within 12 hours of treatment initiation in patients with chronic spontaneous urticaria (CSU).1 Hugh Windom, MD, of Windom Allergy, and colleagues presented the findings at the American Academy of Allergy, Asthma & Immunology (AAAAI) 2026 Annual Meeting in Philadelphia on Friday, February 27.

Novartis announced on September 30, 2026, that the US Food & Drug Administration (FDA) approved remibrutinib (Rhapsido), a highly selective Bruton’s tyrosine kinase (BTK) inhibitor, for adults with CSU.2 The approval was supported by pivotal data from REMIX-1 and REMIX-2: global, randomized, placebo-controlled phase 3 studies evaluating remibrutinib 25 mg twice daily in patients with CSU inadequately controlled on H1-antihistamines. The REMIX trials showed improvements with remibrutinib sustained for up to 52 weeks.

The pooled analysis presented at AAAAI focused specifically on daily Urticaria Activity Score (UAS; range 0–6) to assess short-term symptom dynamics.1 The team sought to assess the symptom control of remibrutinib on a daily basis. Daily UAS was calculated as the sum of hive severity score (HSS) and itch severity score (ISS), with morning and evening values averaged; on day 1, only the evening score, obtained 12 hours after the first dose, was used.

Across both studies, 606 patients received remibrutinib and 306 received a placebo. Baseline mean daily UAS was 4.44 in the remibrutinib group and 4.30 in the placebo group. Within 12 hours of treatment initiation, mean UAS was 3.96 with remibrutinib vs 3.99 with placebo. By day 2, mean UAS declined to 3.09 with remibrutinib vs 3.92 with placebo, and by day 7 to 2.25 vs 3.49, respectively.

Shift analyses showed increasing proportions of patients achieving the lowest UAS severity band (0–1, corresponding to no or mild symptoms). At baseline, 1.3% of patients receiving remibrutinib and 0.7% receiving placebo were in this band. Within 12 hours, these proportions increased to 6.5% and 2.4%, respectively, and by day 7 to 37.0% vs 9.7%.

“Remibrutinib showed early CSU symptom control compared to placebo, with reduction in disease activity noted within the first 12 hours and sustained through day 7,” investigators concluded.

References

1. Windom H, Machado P, Ortmann CE, et al. Remibrutinib Provides Fast Symptom Relief Within the First Week of Treatment in Chronic Spontaneous Urticaria, as Measured by Daily Urticaria Activity Score: Pooled REMIX-1/-2 Studies. Journal of Allergy and Clinical Immunology. 2026;157(2):AB14. doi:https://doi.org/10.1016/j.jaci.2025.12.045

2. Derman C. FDA Approves Remibrutinib for Chronic Spontaneous Urticaria. HCPLive. Published on September 30, 2025. Accessed on March 4, 2026. https://www.hcplive.com/view/fda-approves-remibrutinib-chronic-spontaneous-urticaria