Background/Purpose: Rituximab therapy for ANCA-associated vasculitis (AAV) patients was covered by insurance from 2013 in Japan. Administration of four once-weekly doses of 375 mg/m2 rituximab (RTX) has been indicated for ANCA-associated vasculitis (AAV) as remission induction therapy. However, randomized controlled trial for Japanese AAV patients have never been conducted, although Japanese AAV patients are characterized by the predominance of elderly patients with microscopic polyangiitis (MPA). To compare the efficacy and safety between low-dose versus high-dose RTX therapy as remission induction therapy in Japanese patients with AAV.

Methods: A single center retrospective analysis of 34 consecutive AAV patients with RTX therapy was performed from 2013 to 2019. 25 patients were treated with low-dose RTX infusions, while 9 patients with high-dose RTX infusions. The primary endpoints were complete remission (CR) rate, defined as Birmingham Vasculitis Activity Score (BVAS)=0 and prednisone < 7.5 mg/day, survival rate and severe adverse effects at 6 months. Fisher’s exact test were used for categorical data and Mann-Whitney U test for continuous data to compare background data. Roglank test was used to complete remission rate, compere survival rate and severe adverse effects at 6 months. Results: The frequency of elder (79 vs 71, P=0.045), female (64% vs 21%, P=0.07) patients were significantly high in low-dose group and the duration of hospitalization (22 days vs 38 days, P=0.339) was shorter in low-dose group, whereas the frequency of smoking (36% vs 89%, P=0.017) was significantly higher in high-dose group and the ANCA titer (93.9 vs 176.0, P=0.081) and PSL dose (30mg/day vs 40mg/day, P=0.062) was higher in high-dose group.

 Compared with low-dose group with high-dose group, there was no significant difference with complete remission rate (58% vs 50%, P=0.485), survival rate (87.6% vs 88.9%, P=0.87) and probability of remaining free of severe adverse effects (61.5% vs 88.9%, P=0.176).

Conclusion: Our retrospective analysis indicated that cumulative CR rates and 6 month-survival rates did not significantly differ between low-dose versus high-dose RTX as remission induction therapy in Japanese AAV patients, mostly elderly MPA female patients, although there was no significant difference in severe adverse effects such as opportunistic infections between them.

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ACR Meeting Abstracts - https://acrabstracts.org/abstract/a-single-center-retrospective-analysis-of-efficacy-and-safety-between-low-dose-versus-high-dose-rituximab-as-remission-induction-therapy-with-anca-associated-vasculitis/