Clinical Remission Outcome in Chinese Patients With Severe Asthma With an Eosinophilic Phenotype Receiving Mepolizumab: A Post-hoc Analysis of a Phase 3, Randomized, Double-Blind, Placebo-Controlled Trial

Clinical remission (CR), an emerging treatment goal in asthma, was assessed by a post hoc analysis of a phase 3 study of mepolizumab in severe asthma with an eosinophilic phenotype (SA-EP). Asthmatic patients aged ≥ 12 years, with a blood eosinophil count of ≥ 150 cells/µL at screening (or ≥ 300 cells/µL in the previous year), receiving fluticasone propionate ≥ 500 µg/day or equivalent plus ≥ 1 controller medication, and experiencing ≥ 2 exacerbations in the previous year were randomised to receive add-on mepolizumab or placebo every 4 weeks for 52 weeks. CR was assessed using both 3- and 4-component definitions (at 1 year, no maintenance oral corticosteroids, no clinically significant exacerbations, and asthma control questionnaire-5 [ACQ-5] score ≤ 1.5 for both, plus change from baseline in pre-bronchodilator forced expiratory volume in 1 second ≥ 0 mL for 4-component definition). At week 52, 41.6% (62/149) of mepolizumab-treated patients and 21.2% (32/151) of placebo-treated patients met the 4-component definition (odds ratio [OR], 2.65; 95% confidence interval [CI], 1.59-4.41; P < 0.001), with a difference of 20.4% (95% CI, 9.1%-31.2%), and 54.4% (81/149) of mepolizumab-treated patients and 32.5% (49/151) of placebo-treated patients met the 3-component definition (OR, 2.48; 95% CI, 1.55-3.96; P < 0.001), with a difference of 21.9% (95% CI, 10.5%-32.7%). Baseline characteristics potentially associated with CR in the mepolizumab group were lower ACQ-5 score and lower St George's Respiratory Questionnaire scores. A higher proportion of Chinese SA-EP patients treated with mepolizumab achieved CR compared to those receiving placebo. Certain baseline characteristics are potentially predictive of CR. ClinicalTrials.gov Identifier: NCT03562195.