Low-dose mepolizumab effectiveness in patients suffering from eosinophilic granulomatosis with polyangiitis

Eosinophilic granulomatosis with polyangiitis (EGPA) is a vasculitis characterized by multisystemic manifestations including asthma. Mepolizumab (300 mg/4 weeks) has recently been approved for EGPA. However, real-life data are scarce and report experiences with high doses of mepolizumab intravenously administered (750 mg/4 weeks). The aim of our study was to investigate in a real-life setting whether mepolizumab in EGPA patients at low doses would enable us 1) to control asthma symptoms, 2) to obtain oral corticosteroids (OCS) and/or immunosuppressors tapering and 3) to maintain clinical remission and avoid disease relapses. Mepolizumab (100 mg/4 weeks) was subcutaneously administered for 12 months in 18 EGPA patients with uncontrolled severe asthma. Symptoms, annual asthma exacerbation rates, OCS-sparing effects, lung function and eosinophil activation markers were monitored. The proportion of patients with clinical remission or relapse was also evaluated in month 12. A significant decrease in the annual rate of asthma exacerbations in association with significant changes in asthma control were observed. Specifically, 66.6% of the patients experienced no exacerbations during the mepolizumab treatment. Most patients (77.7%) were able to reduce the daily OCS dose by at least 50%. Four patients also stopped cyclosporine A during the study period. No EGPA relapse was observed and a large majority of the patients achieved clinical remission (94.3%). Clinical benefits were paralleled by reduction in blood eosinophils and serum levels of eosinophil activation markers. Low-dose mepolizumab showed clinically relevant benefits in exacerbation rates, asthma symptoms, OCS and immunosuppressive use in EGPA patients. These effects occurred without any EGPA relapse for extrapulmonary manifestations.