Mepolizumab as a steroid-sparing agent for eosinophilic granulomatosis with poliangiitis: a case series

Background: Treatments for eosinophilic granulomatosis with poliangiitis (EGPA) were limited to systemic corticosteroid and immunomodulatory agent, which have serious adverse effects. In EGPA patients a reduction of corticosteroid often induces relapses. Aims: The MIRRA trial demonstrated that mepolizumab (MEPO) is a steroid-sparing agent for patients with relapsing or refractory EGPA (NEJM 2017). However, the number of enrolled patients was limited. We report 5 EGPA patients treated with MEPO to confirm the finding. Methods: This is retrospective review of five patients with EGPA treated with MEPO. Results: Case 1-4 were 3 men and 1 female and age of onset were 28-70 yo. Treatment was started with PSL 30-60 mg/day with a gradual tapering. All the cases suffered relapses with PSL tapering, and then PSL were increased. In Case 1-3, MEPO 300 mg/day were added at the time of PSL 9-10 mg/day. In Case 4, MEPO 100 mg/day was added at the time of PSL 7 mg/day and, followed by the increase of MEPO (300 mg/day) after tapering of PSL. Currently, in Case 1, 2 and 4, dose of PSL was tapering to 0.5-4 mg/day and these cases maintain remission. In Case 3, a relapse was observed after reduction of PSL even with MEPO. Case 5 was a male and onset age was 75 yo. Treatment was started with PSL 60 mg/day and MEPO 100 mg/day. A relapse was observed during the reduction of PSL. Both PSL and MEPO (300 mg/day) were increased. After that PSL was reduced to 5 mg/day without any replace. No apparent adverse events of MEPO were found in any cases. Conclusions: Remission was obtained in 5 of 3 cases. Consistent with prior published paper, MEPO is an effective steroid-sparing agent for patients with EGPA.