are employees of Genentech, Inc, a member of the Roche group, and own Roche stock. C. E. Brightling is a consultant with fees paid to his institution from Genentech, Inc, and Regeneron; received research grants and was a consultant with fees paid to his institution from AstraZeneca, GlaxoSmithKline, Sanofi, Boehringer Ingelheim, Roche/Genentech, Chiesi, 4D Pharma, Mologics, and Novartis.Background: The IL-33/ST2 pathway is linked with asthma susceptibility. Inhaled allergens, pollutants, and respiratory viruses, which trigger asthma exacerbations, induce release of IL-33, an epithelial-derived ''alarmin.'' Astegolimab, a human IgG 2 mAb, selectively inhibits the IL-33 receptor, ST2. Approved biologic therapies for severe asthma mainly benefit patients with elevated blood eosinophils (type 2-high), but limited options are available for patients with low blood eosinophils (type 2-low). Inhibiting IL-33 signaling may target pathogenic pathways in a wider spectrum of asthmatics. Objectives: This study evaluated astegolimab efficacy and safety in patients with severe asthma. Methods: This double-blind, placebo-controlled, dose-ranging study (ZENYATTA [A Study to Assess the Efficacy and Safety of MSTT1041A in Participants With Uncontrolled Severe Asthma]) randomized 502 adults with severe asthma to subcutaneous placebo or 70-mg, 210-mg, or 490-mg doses of astegolimab every 4 weeks. The primary endpoint was the annualized asthma exacerbation rate (AER) at week 54. Enrollment caps ensured 30 patients who were eosinophil-high (> _300 cells/mL) and 95 patients who were eosinophil-low (<300 cells/mL) per arm. Results: Overall, adjusted AER reductions relative to placebo were 43% (P 5 .005), 22% (P 5 .18), and 37% (P 5 .01) for 490mg, 210-mg, and 70-mg doses of astegolimab, respectively. Adjusted AER reductions for patients who were eosinophil-low were comparable to reductions in the overall population: 54% (P 5 .002), 14% (P 5 .48), and 35% (P 5 .05) for 490-mg, 210mg, and 70-mg doses of astegolimab. Adverse events were similar in astegolimab-and placebo-treated groups. Conclusions: Astegolimab reduced AER in a broad population of patients, including those who were eosinophil-low, with inadequately controlled, severe asthma. Astegolimab was safe and well tolerated. (J Allergy Clin Immunol 2021;nnn:nnnnnn.)
