Low-dose rituximab as induction therapy for ANCA-associated vasculitis

Administration of four once-weekly doses of 375 mg/m² rituximab (RTX) is commonly used as remission induction therapy for ANCA-associated vasculitis (AAV). Low-dose RTX has been recently shown to produce closely similar results to conventional treatments in other autoimmune diseases. However, the therapeutic potential of this approach in AAV remains largely unknown. Here, we analyzed the efficacy and tolerability of high- and low-dose regimens of RTX in patients with AAV. We retrospectively examined AAV patients who met the classification algorithm of Watts et al. from 2006 to 2016. Patients were divided into high- (HD) and low-dose (LD) RTX groups. HD-RTX was the original regimen while LD-RTX consisted of two once-weekly doses of 375 mg/m². Cumulative complete remission (CR) rates for 1 year were compared, and serial changes in peripheral B cell counts and serious adverse events were monitored. Apart from a higher percentage of elderly patients in the LD group (p < 0.01), the 17 patients with HD-RTX and 11 patients with LD-RTX showed no significant differences in clinical characteristics, including Birmingham Vasculitis Activity Score (BVAS), Vasculitis Damage Index (VDI), and the initial dose of glucocorticoid. On 1-year observation, cumulative CR rates did not significantly differ (p = 0.20). Further, peripheral B cell counts and incidence of serious adverse events also did not differ. Cumulative CR rate did not significantly differ between LD and HD groups. Further study is warranted to confirm these results.