Response to Mepolizumab Treatment in Patients with Severe Eosinophilic Asthma and Atopic Phenotypes

PURPOSE: Improved understanding of characteristics that may influence treatment response across phenotypes may help guide treatment decisions. PATIENTS AND METHODS: This was a post hoc analysis of MENSA, a multicenter, randomized, double-blind, placebo-controlled trial (NCT01691521). Patients aged ≥12 years with severe eosinophilic asthma received mepolizumab (75 mg intravenously or 100 mg subcutaneously) or placebo, plus standard of care, every 4 weeks for 32 weeks. Outcomes assessed were the annualized rate of clinically significant exacerbations and change from baseline in Asthma Control Questionnaire (ACQ)-5 score. Subgroup analyses were performed by baseline blood eosinophil count (<150, ≥150–300, ≥300 cells/μL) within atopic subgroups (non-atopic [specific immunoglobulin E <0.35 kU/L], atopic [≥0.35–17.5 kU/L], strongly atopic [>17.5 kU/L]), and by house dust mite (HDM) sensitivity. RESULTS: Of 576 patients analyzed, 272 were non-atopic, 181 were atopic and 94 were strongly atopic; 29 had missing atopy data. In patients with blood eosinophil counts ≥300 cells/µL, mepolizumab versus placebo reduced clinically significant exacerbations by 74%, 43% and 25% in the non-atopic, atopic and strongly atopic subgroups. Similar reductions were observed in all atopic subgroups in other blood eosinophil count categories where there were sufficient patient numbers for analysis, except for non-atopic patients with baseline blood eosinophil counts of <150 cells/μL. Improvements in ACQ-5 scores of –0.75, –0.73 and –0.78 with mepolizumab versus placebo were observed in non-atopic, atopic and strongly atopic patients with blood eosinophil counts ≥300 cells/µL; consistent improvements in ACQ-5 were not observed in patients with blood eosinophil counts <150 or ≥150–300 cells/μL. Reductions in clinically significant exacerbations with mepolizumab versus placebo were also observed irrespective of sensitivity to HDMs. CONCLUSION: Mepolizumab was associated with a trend for reductions in clinically significant exacerbations and improved asthma control versus placebo in patients with severe eosinophilic asthma, irrespective of atopic status or HDM sensitivity.