Remibrutinib in Chronic Spontaneous Urticaria

Background: Chronic spontaneous urticaria is an idiopathic syndrome defined by recurring itch, hives, or angioedema (or a combination of these symptoms) for more than 6 weeks. Remibrutinib, an oral, highly selective Bruton's tyrosine kinase inhibitor, showed efficacy and favorable safety in phase 2b trials. Data from phase 3 trials are needed. Methods: In the identical, multicenter, double-blind, randomized, placebo-controlled REMIX-1 and REMIX-2 trials, we evaluated the efficacy and safety of remibrutinib in patients with symptomatic chronic spontaneous urticaria after treatment with second-generation H1-antihistamines. Patients were randomly assigned in a 2:1 ratio to receive oral remibrutinib at a dose of 25 mg twice daily or placebo. The primary end point was the change from baseline to week 12 in the urticaria activity score during a 7-day period (UAS7), which comprises severity scores for itch and hives during 1 week (scores range from 0 to 42, with higher scores indicating greater severity). Key secondary end points included adverse events and a UAS7 of 6 or lower at weeks 2 and 12 and a UAS7 of 0 at week 12. Results: A total of 470 patients in REMIX-1 and 455 in REMIX-2 were randomly assigned to receive either remibrutinib (313 and 300 patients, respectively) or placebo (157 and 155 patients, respectively). The remibrutinib group had a significantly greater decrease in the UAS7 at week 12 than the placebo group (least-squares mean [±SE] change, -20.0±0.7 vs. -13.8±1.0 [P<0.001] in REMIX-1 and -19.4±0.7 vs. -11.7±0.9 [P<0.001] in REMIX-2), which appeared to be sustained through week 24. At week 12, significantly more patients in the remibrutinib group than in the placebo group had a UAS7 of 6 or lower (REMIX-1, 49.8% vs. 24.8% [P<0.001]; REMIX-2, 46.8% vs. 19.6% [P<0.001]) and a UAS7 of 0 (REMIX-1, 31.1% vs. 10.5% [P<0.001]; REMIX-2, 27.9% vs. 6.5% [P<0.001]). The percentages of patients with any adverse event and with serious adverse events were similar in the remibrutinib group and the placebo group, although a higher percentage of patients in the remibrutinib group than in the placebo group had petechiae (3.8% vs. 0.3% in the combined groups). Conclusions: Treatment with oral remibrutinib resulted in a significant improvement in a composite measure of itching and hives at week 12. (Funded by Novartis Pharmaceuticals; REMIX-1 and REMIX-2 ClinicalTrials.gov numbers, NCT05030311 and NCT05032157, respectively.).