Real-World Effectiveness of Tezepelumab in Severe Asthma: A 12-Month Canadian Cohort Study.

Rationale: Many patients with asthma remain poorly controlled despite high-intensity inhaled therapy. Tezepelumab, a monoclonal antibody targeting thymic stromal lymphopoietin, has shown benefit in both type 2 (T2)-high and T2-low asthma. Real-world evidence in diverse clinical populations remains limited. Objective: To evaluate the real-world effectiveness of tezepelumab in adults with severe asthma, including changes in exacerbations, lung function, and dyspnea across clinically relevant subgroups. Methods: We retrospectively identified adults with severe asthma who initiated tezepelumab between July 2022 and April 2025 at two centres in Ontario, Canada. Patients who completed at least 12 months of therapy were included (n=75). The primary outcome was the comparison of asthma exacerbation rates (AER) requiring oral corticosteroids during the 12 months before and after treatment initiation. Secondary outcomes included AER stratified by smoking history, chronic obstructive pulmonary disease diagnosis, prior asthma biologic use, blood eosinophil count, and evidence of T2 inflammation. Changes in post-bronchodilator forced expiratory volume in 1 second (FEV Measurements and Main Results: In the overall patient population, AER decreased from 2.23 to 0.19 exacerbations per patient-year (rate ratio, 0.08; 95% CI, 0.04, 0.14), corresponding to a 92% reduction. Exacerbations requiring an ED visit or hospitalization decreased by 87%. Substantial reductions in AER were observed across the assessed patient subgroups. Overall, mean FEV Conclusion: In this real-world Canadian cohort, 12 months of tezepelumab was associated with substantial reductions in asthma exacerbations and improvements in lung function and dyspnea across diverse clinical subgroups.