Background/Purpose: Contrary to many Western countries, MPO-ANCA-associated vasculitis (MPO-AAV) is dominant in Japan. The therapeutic response to rituximab (RTX) may differ. Therefore, we conducted a retrospective analysis of the clinical database of the 66 AAV-patients in our hospital treated with RTX.

Methods: All patients met the CHCC classification criteria for MPA and GPA at disease onset. Sixty-six patients [41(64%) females)] followed for at least six months since 2013 (up to Oct 2021) were analysed for clinical course, including remission rates. Remission was defined as Birmingham Vasculitis Activity Score (BVAS) 0 at six months. Disease flare defined as increased disease activity required intensification of immunosuppressive therapy.

Results: Of the 66 patients (32 MPO-MPA, 17 MPO-GPA, and 17 PR3-GPA),62 patients [31 newly diagnosed(N-group) or 31 relapsing diseases (R-group)] received a remission induction with RTX and 4 patients received maintenance RTX therapy. The mean age at the initiation of RTX was 65.9±16.4 years, 28 patients (42%) over 75 years, mean BVAS was 10.6±7.5, 47% had renal involvement, and mean serum creatinine was 1.6±1.2 mg/dl. Overall, 82% (51/62 patients) achieved remission at six months. Eighty-four percent (26/31) in N-group and 39% (12/31) in R-group received glucocorticoid pulse therapy. Mean daily dose of PSL at RTX initiation/six months were 46.5±11.2 mg/10.1±0.2 mg and 26.8±16.2 mg/9.7±0.2mg in newly diagnosed and relapsing cases, respectively. There were three refractory cases who switched another induction therapy (1MPO-MPA, 1MPO-GPA, 1 PR3-GPA) within six months. After mean follow-up 2.6±2.2 years, 39/60 patients received maintenance RTX therapy (six patients lost to follow-up). Maintenance therapy was given more often based on changes in CD19+ counts and/or ANCA titer in 57% (22/39 cases) as compared to scheduled administration every 6 months. There were 9 relapses in 7 cases (mean 16.6 ± 9.2 months after the last RTX), with 67% (6/9) of relapse seen in GPA (3 in MPO-MPA, 1 in MPO-GPA, 5 in PR3-GPA). Retreatment with RTX successfully induced remission in all relapsed cases. Death occurred in 9 patients [5 infection, 2 cardiovascular disease, 1 malignancy (unrelated), 1 AAV], three of which were due to infection within 6 months.

Conclusion: These results showed that RTX is effective and has an acceptable safety profile in relatively elder AAV patients in daily practice.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/analysis-of-clinical-outcomes-in-anca-associated-vasculitis-treated-with-rituximab-eighty-years-a-single-center-experience-in-japan/