Disease burden and efficacy of mepolizumab in patients with severe asthma and blood eosinophil counts of ≥150-300 cells/μL.

BACKGROUND: In patients with severe eosinophilic asthma, treatment decisions can be determined by blood eosinophil counts; however, a specific blood eosinophil threshold has not been defined for starting mepolizumab treatment.

METHODS: We summarized the disease burden and efficacy of mepolizumab in patients with severe eosinophilic asthma and baseline blood eosinophil counts of ≥150-300 cells/μL and ≥300 cells/μL using data from the mepolizumab clinical development program (DREAM [NCT01000506], MENSA [NCT01691521], SIRIUS [NCT01691508] and MUSCA [NCT02281318]).

RESULTS: The morbidity of asthma in patients with baseline blood eosinophil counts ≥150-300 cells/μL was similar to that in patients with blood eosinophil counts ≥300 cells/μL, with similar rates of exacerbations (2.8-3.5 events/year versus 2.8-3.8 events/year, respectively), asthma related emergency room visits, intubations and near fatal events. Use of maintenance oral corticosteroids (OCS) was similar across blood eosinophil count subgroups. Reductions in the rates of clinically significant exacerbations with mepolizumab versus placebo ranged from 27 to 49% in patients with blood eosinophil counts of ≥150-300 cells/μL for DREAM, MENSA and MUSCA. The odds of achieving a reduction in OCS in SIRIUS was 2.03 (95% CI: 0.53, 7.75) versus 1.79 (95% CI: 0.71, 4.52) in patients with blood eosinophil counts ≥150-300 cells/μL and ≥300 cells/μL, respectively.

CONCLUSION: There is a high unmet clinical need in patients with blood eosinophil counts ≥150-300 cells/μL, and a clinically meaningful benefit is seen with mepolizumab in this subgroup. Mepolizumab is an efficacious treatment option for patients with blood eosinophil counts ≥150 cells/μL.