Abstract
We herein report three cases of microscopic polyangiitis (MPA). Two patients were administered avacopan in combination with glucocorticoid (GC), whereas one patient was treated with avacopan monotherapy; none of the patients were co-administered either rituximab or cyclophosphamide. The doses of GC were successfully reduced after the introduction of avacopan in the two patients, and the serum C-reactive protein levels decreased in the patient treated with avacopan monotherapy. Avacopan may therefore be effective either in combination with GC or as monotherapy, even for patients at a high risk of developing adverse effects when administered rituximab or cyclophosphamide.