Predictors of the enhanced response to mepolizumab treatment for severe eosinophilic asthma: A retrospective, long-term study

Abstract Mepolizumab significantly reduces the number of annual exacerbations (AEs) and the maintenance dose of systemic corticosteroids (CSs) in patients with severe eosinophilic asthma (SEA). However, there are few studies based on real life with a long-term observational period in Japan. Between July 2016 and December 2019, 24 Japanese patients received mepolizumab at Jikei University Hospital for at least 12 months. We retrospectively evaluated these characteristics, AEs and CS doses. To elucidate the predictors of the enhanced responders, we performed multivariate logistic regression analysis. After introduction, asthma symptoms improved and were maintained for over a year. The number of AEs and CS doses significantly decreased. In the subgroup analysis, the younger than 65 years-old, body mass index (BMI) < 25 kg/m2, eosinophilic chronic rhinosinusitis, or eosinophil count ≥ 400/mm3 exhibited effective reductions in either AEs or CS doses with mepolizumab treatment. The percentage change in the AEs (≤ −75%) was significantly decreased in the patients with a BMI < 25 using multivariate logistic regression analysis (odds ratio 31, 95% confidence interval: 1.4–700, P = 0.03). In real-life, BMI < 25 could be a predictor for reductions in AEs with mepolizumab treatment in the patients with SEA. Abbreviations IL, interleukin; CS, corticosteroid; SEA, severe eosinophilic asthma; BMI, body mass index; ECRS, eosinophilic chronic rhinosinusitis; CRSwNP, chronic rhinosinusitis with nasal polyps