Effect of mepolizumab in severe eosinophilic asthma according to omalizumab eligibility

Background: Patients with severe asthma can present with overlapping eosinophilic and allergic phenotypes, which makes it challenging when deciding which biologic therapy is most appropriate to reduce exacerbations and help achieve asthma control. Objective: This post hoc meta-analysis evaluated the efficacy of the licensed dose of mepolizumab (100 mg administered subcutaneously [SC]) versus placebo in patients with severe eosinophilic asthma (SEA), according to omalizumab eligibility and associated allergic characteristics. Methods: Data from two Phase 3 studies (MENSA [MEA115588/NCT01691521]; MUSCA [200862/NCT02281318]) were analyzed. Patients ≥12 years of age with SEA who experienced ≥2 exacerbations in the previous year received placebo, mepolizumab 100 mg SC or 75 mg intravenously, plus standard of care (high-dose inhaled corticosteroids and other controllers), every 4 weeks. Data from patients who received ≥1 dose placebo or mepolizumab 100 mg SC were used for this analysis. The primary endpoint was the rate of clinically significant exacerbations; other outcomes included forced expiratory volume in 1 s (FEV₁), Asthma Control Questionnaire (ACQ-5) score and quality of life measured using St George's Respiratory Questionnaire (SGRQ). Results: Rate reductions in clinically significant exacerbations with mepolizumab versus placebo were similar in omalizumab eligible and ineligible patients (57% vs 55%). FEV₁, ACQ-5 and SGRQ scores improved with mepolizumab versus placebo regardless of omalizumab eligibility, Immunoglobulin E levels, or atopic status. Conclusion: This analysis indicated that mepolizumab 100 mg SC has clinical benefit in patients with blood eosinophil counts ≥150 cells/μL (or history of ≥300 cells/μL), regardless of allergic characteristics or omalizumab eligibility.