Real‐World Effectiveness and Safety of Mepolizumab in Pediatric Severe Eosinophilic Asthma: A Multicenter Study

BACKGROUND: Severe asthma (SA) in children is a complex condition with high morbidity and healthcare costs. Mepolizumab, an anti-interleukin-5 biologic, is approved for severe eosinophilic asthma (SEA) in patients ≥ 6 years, yet long-term real-world pediatric data remain limited. AIM: To assess the long-term safety and effectiveness of mepolizumab in pediatric SEA, focusing on lung function, oral corticosteroid (OCS) use, and exacerbation rates. METHODS: This retrospective, multicenter study examined the medical records of 33 patients with SEA (aged 6-17 years) who received mepolizumab treatment at three tertiary centers in Turkiye. Inclusion criteria included GINA-defined SA, ≥ 2 severe exacerbations in the previous year requiring OCS, high-dose ICS plus a second controller, and elevated eosinophil counts. Data on exacerbations, pulmonary function tests (PFTs), OCS use, ACT scores, eosinophils, and adverse events were collected over 24 months. RESULTS: At baseline, patients showed poor asthma control (median ACT: 13), impaired lung function (FEV1%: 62%), and frequent exacerbations (median: 7/year). Mepolizumab significantly reduced exacerbation rates (median: 7 to 0-0.05 at 12/24 months, p = 0.005) and OCS use (87.9% OCS-free by 3 months). ACT scores improved (median: 13-25, p < 0.001), as did FEV1% (62% to 89%, p < 0.001) at 24 months. Eosinophil counts decreased markedly (460 to 50 cells/µL, p < 0.001). The treatment was well-tolerated; one patient discontinued due to anaphylaxis and four due to lack of efficacy. CONCLUSION: Mepolizumab showed sustained effectiveness and good tolerability in pediatric SEA, significantly reducing exacerbations and OCS use while improving asthma control and lung function. These findings support its real-world utility and underscore the need for careful patient selection and monitoring.