Microscopic polyangiitis presenting as rapidly progressive glomerulonephritis treatment with the complement C5a receptor inhibitor, Avacopan : three case report

Abstract

Abstract : The antineutrophil cytoplasmic antibody （ANCA）-associated vasculitis was approved for treatment with the complement C5a receptor inhibitor, Avacopan, in September 2021.　However, experience with its use in microscopic polyangiitis （MPA）, which is the most common form of ANCA-associated vasculitis in Japan and presents with rapid progressive glomerulonephritis （RPGN）, is limited.　 There are few reports in the literature regarding the use of Avacopan to treat MPA with a clinical presentation of RPGN.　We treated three MPA patients with RPGN using a combination of Avacopan and Prednisolone.　In all cases, renal function, urinary findings, and inflammatory response improved during the one to three-month observation period from the start of treatment.　The clinical results suggest that treatment with Avacopan helped improve MPA-induced RPGN in these patients after a short observation period.　Nonetheless, long-term follow-up is required to confirm the maintenance rates of disease remission and the incidence of adverse events.