Introduction <p>Remibrutinib, an oral, highly selective Bruton’s tyrosine kinase (BTK) inhibitor, was recently approved by the US Food and Drug Administration (FDA) for the treatment of chronic spontaneous urticaria (CSU). Dupilumab, an interleukin-4 receptor-α monoclonal antibody, was approved by the FDA for CSU in early 2025. Here, we report the design of RECLAIM (NCT06868212), a phase 3b study that aims to compare the efficacy of remibrutinib and dupilumab at early timepoints in patients with symptomatic CSU despite treatment.</p> Methods <p>This US-based, multicenter, randomized, double-blind, double-dummy study will include approximately 400 patients with moderate-to-severe CSU who remain symptomatic despite treatment with second-generation H₁-antihistamines (sgH₁-AHs). Patients will be randomized 1:1 to receive either oral remibrutinib (25&#xa0;mg twice daily) or subcutaneous dupilumab (600&#xa0;mg loading dose; 300&#xa0;mg every 2&#xa0;weeks), in addition to sgH₁-AHs. The study consists of a screening period of up to 4&#xa0;weeks, a 12-week core treatment period, and a safety follow-up period of up to 12&#xa0;weeks. Patients with chronic inducible urticaria or other skin diseases with symptoms of urticaria, angioedema, or chronic itching, and patients with prior use of remibrutinib, BTK inhibitors, or dupilumab, are excluded. The primary endpoint is absolute change from baseline in weekly Urticaria Activity Score (UAS7) at week 4. Secondary endpoints include: absolute change from baseline in UAS7 at week 1 and in weekly Itch Severity Score and Hives Severity Score at week 4; achievement of well-controlled disease (UAS7 ≤ 6) at weeks 2 and 4; complete disease control (UAS7 = 0) at week 4; and safety assessments.</p> Planned Outcomes <p>RECLAIM will evaluate the early efficacy of remibrutinib versus dupilumab in patients with CSU. The study is currently recruiting patients.</p> Trial Registration <p>ClinicalTrials.gov identifier, NCT06868212.</p>