Regression of a Refractory Pulmonary Lesion in Granulomatosis with Polyangiitis Following the Addition of Avacopan.

Avacopan, a complement component 5a (C5a) receptor antagonist, is an emerging therapeutic agent for anti-neutrophil cytoplasmic autoantibody (ANCA)-associated vasculitis. However, its intrinsic efficacy remains unclear. A 74-year-old woman with granulomatosis with polyangiitis (GPA) presenting as a pulmonary mass, sinusitis, otitis media with hearing loss, and mononeuritis multiplex is reported. Initial remission was achieved with prednisolone and cyclophosphamide followed by maintenance with low-dose prednisolone and azathioprine. After 3 years, she relapsed with recurrent blood-stained sputum and enlargement of the pulmonary lesion despite negative ANCA titers. Infection and malignancy were excluded. Avacopan (60 mg/day) was introduced with low-dose prednisolone and azathioprine. Over 12 months, the pulmonary mass regressed, and blood-stained sputum improved, enabling complete withdrawal of prednisolone after 20 months. This case suggests a potential direct effect of avacopan on pulmonary inflammatory lesions in GPA and highlights the importance of long-term treatment evaluation. Cite this article as: Nakagomi D, Kubota S, Kobayashi Y, Hanai S. Regression of a refractory pulmonary lesion in granulomatosis with polyangiitis following the addition of avacopan. Eur J Rheumatol. 2026, 13, 0062, doi:10.5152/eurjrheum.2026.25062.