Long-term efficacy of mepolizumab on eosinophilic granulomatosis with polyangiitis: a retrospective study

Aim: Eosinophilic granulomatosis with polyangiitis (EGPA) is a vasculitis characterized by eosinophilic inflammation. Patients with EGPA are treated with systemic glucocorticoids and immunosuppressive drugs to induce and maintain remission. However, most patients relapse after tapering glucocorticoids, and there are refractory cases with inadequate response to glucocorticoids. Mepolizumab, a humanized anti-IL-5 antibody, is approved for relapsing or refractory EGPA. Furthermore, recent studies have reported the efficacy of benralizumab, a humanized anti-IL-5 receptor α antibody, in EGPA. Here, we investigate the efficacy of biologics on consecutive cases of EGPA. Methods: We retrospectively collected patients with EGPA treated with mepolizumab in addition to glucocorticoids at the Department of Pulmonary Medicine in Kagoshima University Hospital and Imakiire General Hospital. In this study, we compared the effects of biologics on inflammatory parameters between pre- and post-treatment of biologics in patients with EGPA. Results: Ten patients were included in the study. All patients were treated with mepolizumab, and one was switched to benralizumab later. Treatment with biologics markedly reduced EGPA relapse from 70% (pre-treatment) to 20% (post-treatment), Birmingham Vasculitis Activity Score from 8.4 to 4.0, peripheral blood eosinophil counts from 470.3 /µL to 40.5 /µL, and glucocorticoid doses from 7.3 mg/dL to 1.6 mg/dL. In contrast, lung function and fractional exhaled nitric oxide levels were not affected by treatment with biologics. Furthermore, the duration of biologics was positively correlated with symptom improvement. Conclusions: Treatment with mepolizumab for EGPA was effective in glucocorticoid sparing, symptom reduction, and relapse prevention. Mepolizumab is expected to reduce the risk of glucocorticoid-related adverse events. Therefore, continued administration as well as early intervention with mepolizumab for EGPA might be important to conserve future medical resources and control the disease.