Factors associated with drug retention of mepolizumab in patients with eosinophilic granulomatosis with polyangiitis: A multicentre REVEAL cohort study

ABSTRACT Objectives To determine the current retention rate of mepolizumab (MPZ) and identify factors associated with drug retention in patients with eosinophilic granulomatosis with polyangiitis (EGPA) in the Kansai multicentre cohort (REVEAL cohort). Methods Sixty patients diagnosed with EGPA and treated with MPZ between December 2016 and June 2023 were enrolled. The clinical characteristics, including laboratory data, treatments administered, and disease course outcomes, were collected retrospectively. The patients were stratified into MPZ continuation (n = 53) and discontinuation (n = 7) groups, and drug retention was statistically compared using the log-rank test. Results The median age of patients was 54.5 years, with 55% females, and 33% antineutrophil cytoplasmic antibody-positive at disease onset. MPZ exhibited a retention rate of 78.7% after 5 years. The reasons for discontinuation included treatment of coexisting diseases, inadequate response, and remission. Patient characteristics at disease onset were comparable between the groups. Patients receiving immunosuppressants (IS) before MPZ introduction demonstrated significantly higher retention rates (P = 0.038). During the final observation, the MPZ continuation group had a lower vasculitis damage index score (P = 0.027). Conclusions MPZ exhibited a high 5-year retention rate, particularly in patients requiring IS. This study implies that long-term use of MPZ may mitigate irreversible organ damage.