Efficacy and safety of mepolizumab in a Chinese population with severe asthma: a phase III, randomised, double-blind, placebo-controlled trial

Background In China, the prevalence of severe asthma with eosinophilic phenotype is rising, yet treatment options are limited. Mepolizumab is the first targeted biologic therapy for eosinophilic-driven disease in China. This study (clinicaltrials.gov identifier NCT03562195 ) evaluated efficacy and safety of mepolizumab in Chinese patients with severe asthma. Methods The phase III, multicentre, randomised, placebo-controlled, double-blind, parallel-group study enrolled patients aged ≥12 years with severe asthma, with two or more exacerbations in the previous year, and on inhaled corticosteroids plus at least one controller medication. Following a 1–4-week run-in, patients were randomised 1:1 to mepolizumab 100 mg or placebo subcutaneously every 4 weeks for 52 weeks. The primary end-point was annualised rate of clinically significant exacerbations (CSEs) through week 52. Secondary end-points were time to first CSE, frequency of CSEs requiring hospitalisation/emergency department visits or hospitalisation over 52 weeks, mean change in St George's Respiratory Questionnaire (SGRQ) total score and pre-bronchodilator forced expiratory volume in 1 s (FEV 1 ) at week 52; safety was evaluated. Results The modified intention-to-treat population included 300 patients. At week 52 with mepolizumab versus placebo, annualised rate of CSEs was 65% lower (0.45 versus 1.31 events per year; rate ratio 0.35, 95% CI 0.24–0.50; p<0.001); time to first CSE longer (hazard ratio 0.38, 95% CI 0.26–0.56; p<0.001) and number of CSEs requiring hospitalisation/emergency department visit lower (rate ratio 0.30, 95% CI 0.12–0.77; p=0.012). From baseline to week 52, SGRQ score improved (p=0.001) and pre-bronchodilator FEV 1 increased (p=0.006). Incidence of adverse events was similar between treatment groups. Conclusion Mepolizumab provided clinical benefits to patients with severe asthma in China and showed a favourable benefit–risk profile.