Real-World Effectiveness and Safety of Mepolizumab in Severe Eosinophilic Asthma: Insights From the Korean Severe Asthma Registry (KoSAR)

Mepolizumab, an interleukin-5 antagonist, is globally recognized for its efficacy in randomized controlled trials for the treatment of severe eosinophilic asthma. The present study explored its real-world effectiveness and safety in a Korean cohort, filling a critical gap in current research. This multi-center retrospective study used data from the Korean Severe Asthma Registry, involving 67 patients treated with mepolizumab for uncontrolled severe asthma between September 2017 and July 2022. We assessed the effects of treatment on acute exacerbations, oral corticosteroid (OCS) maintenance dose, lung function, and quality of life. The notable findings included a marked reduction in the proportion of patients experiencing acute exacerbations, with 73.0% of patients reporting no exacerbations during the 6-month treatment period. At baseline, 31.8% of patients had reported no exacerbations over the prior 12 months. The OCS maintenance doses also decreased substantially, with only 3.2% of patients requiring OCS after 6 months. Additionally, there was an improvement in lung function. No severe adverse reactions were reported in this study, highlighting the safety of mepolizumab. This study confirmed that mepolizumab reduced exacerbations and OCS use, with additional improvements seen in asthma control, lung function, and patient-reported quality of life. These real-world findings support broader applications and reinforce the need for further research to optimize treatment strategies. Despite certain limitations, such as the small sample size and retrospective design, this study significantly contributes to the understanding of the real-world efficacy and safety of mepolizumab.