Effect of Avacopan on Kidney Function in Maintenance Therapy of ANCA-Associated Vasculitis: Single-Center Experience in Japan

Background: Avacopan (AVA) is used to treat ANCA-associated vasculitis (AAV), and several reports have shown that it can reduce glucocorticoid (GC) doses and improve renal function during remission induction therapy. However, there have been few studies on cases in which AVA was initiated during the maintenance therapy. Therefore, we conducted a retrospective analysis of the clinical database of AAV patients in the maintenance phase who had been treated with AAV for over one year prior to initiating AVA at our hospital. Methods: Eight patients (4 females, 50%) who initiated AVA during the maintenance phase at our hospital between 2023 and 2024 were included in the study. The GC dosage, renal function, and other relevant parameters were evaluated one year prior to AVA initiation and from 12 to 48 weeks after AVA initiation. Results: AVA was used during the maintenance phase in 8 patients (6 MPO-MPA, 1 MPO-GPA, and 1 PR3-GPA) with AAV. Of these patients, 7 exhibited nephritic urinary findings and 4 had RPGN at the time of AAV onset. At onset, the mean age was 61.1±11.5 years and BVAS was 13.4±4.2. At the start of AVA, the mean age was 67.8±9.1 years (oldest 79 years) and the BVAS was 0. The duration from induction of remission at onset to AVA initiation was 2481±2355 days (median 5.2 years). One year prior to the initiation of AVA, the mean eGFR was 43.3±16.0 mL/min/1.73m2. At the time of AVA initiation, the mean eGFR was 41.7±13.4 mL/min/1.73m2, PSL was used 6.1±2.2 mg/day, and rituximab was used as a concomitant immunosuppressant in 5 cases (63%). After that, there were no relapses, deaths, or renal deaths in patients who continued AVA. PSL was reduced in 4 cases (50%), and the PSL dose at the last observation was 4.9±1.7 mg/day. eGFR decreased in one case, but was maintained or increased in the other cases, and the eGFR at the final observation was 44.9 ± 14.4 mL/min/1.73m2. Compared to the time when AVA was initiated, the rate of change in eGFR at the last observation increased by 7.7 ± 9.1%, and some cases showed an improvement in renal function of up to 24.5%. Conclusion: These results indicated that AVA may be effective in inhibiting the progression of renal damage and reducing GC dosage even in the maintenance phase of AAV therapy in daily practice in Japan.