Efficacy and Safety of Mepolizumab in Eosinophilic Granulomatosis with Polyangiitis: A Systematic Review and Meta-Analysis

Introduction: Eosinophilic granulomatosis with polyangiitis (EGPA), known previously as Churg-Strauss syndrome, is a systemic vasculitis involving small to medium-sized vessels. Corticosteroids and immunosuppressive therapies historically managed EGPA, but these therapies are often associated with adverse effects and a high likelihood of relapse. Recently, mepolizumab (MPZ), a monoclonal antibody that targets interleukin-5 (IL-5) has shown promising results, especially for those EGPA patients who are refractory to conventional corticosteroid therapy. Methods: A systematic literature search was conducted on PubMed, Cochrane Library, Science Direct, Google Scholar, ClinicalTrials.gov, and the American Society of Hematology (ASH) from inception to June 01, 2024, using MeSH terms and keywords used for “Churg-Strauss syndrome”, “EGPA”, “Eosinophilic Granulomatosis with Polyangiitis”, “Allergic Granulomatosis”, and “Mepolizumab”. Clinical remission and adverse effects were the primary outcomes. Secondary outcomes were prednisolone-free remission, serious adverse effects, relapses, and asthma exacerbations. The random-effects model with the Freeman Tukey double arcsine transformation was used to pool overall prevalence with 95% CI for dichotomous variables in MetaXL version 5.3. Results: Seventeen studies were included (n = 1,075 patients). Nine studies (178 out of 311 patients) reported data on clinical remission with a pooled prevalence of 65% (95% CI: 49%-79%, I2=86%). Twelve studies (385 out of 853 patients) reported data on any adverse effects after treatment with a pooled prevalence of 52% (95% CI: 25%-77%, I2 =98%). Three studies reported remission in both 100 mg and 300 mg subgroups with a pooled prevalence of 50% (95% CI: 22%-78%, I2 =85%) and 72% (95% CI: 56%-86%, I2 =7%) respectively. Seven studies (73 out of 238 patients) reported prednisolone-free remission with a pooled prevalence of 32% (95% CI: 21%-43%, I2=65%). Conclusion: The systematic review and meta-analysis suggests that MPZ is effective and safe for treating patients with EGPA. Subgroup analysis by dosage regimen indicated that 100 mg could be more effective for inducing prednisolone-free remission with fewer serious adverse effects and fewer relapses.