Clinical Features of Patients with Active Eosinophilic Granulomatosis with Polyangiitis Successfully Treated with Mepolizumab

Abstract

<b><i>Background:</i></b> In some patients with eosinophilic granulomatosis with polyangiitis (EGPA), remission cannot be induced, despite treatment with corticosteroids and immunosuppressants. We evaluated the clinical features of patients with EGPA in whom mepolizumab was effective. <b><i>Methods:</i></b> There were 59 EGPA patients treated at Hiratsuka City Hospital, Japan, between April 2018 and September 2020, and 30 of them received mepolizumab. Twenty (66.7%) experienced a “marked effect” (the daily dose of corticosteroid or immunosuppressant could be decreased, or the interval between intravenous immunoglobulin (IVIG) treatments could be prolonged) and 10 (33.3%) experienced a “weak effect” (these measures were not achieved). Eosinophil numbers, serum IgG levels, daily doses of corticosteroids and immunosuppressants, and the interval between IVIG treatments at diagnosis and before and after mepolizumab initiation were determined. <b><i>Results:</i></b> Eosinophil numbers at diagnosis were significantly higher in the marked-effect group than in the weak-effect group (<i>p</i> &#x3c; 0.05) but not before mepolizumab initiation or at the last visit. Birmingham Vasculitis Activity Scores (BVASs) before mepolizumab initiation (<i>p</i> &#x3c; 0.05) and at last visit (<i>p</i> &#x3c; 0.01), and frequency of relapse before treatment initiation (<i>p</i> &#x3c; 0.05) were significantly higher, and the serum IgG level before mepolizumab treatment was significantly lower in the weak-effect group than in the marked-effect group. The weak-effect group received higher doses of corticosteroids, even if the corticosteroid dose could be reduced for a while after mepolizumab initiation. <b><i>Conclusion:</i></b> High peripheral blood eosinophil numbers at EGPA diagnosis were suggestive of a positive clinical response to mepolizumab.