Support for rituximab maintenance therapy in ANCA-associated vasculitis
medwireNews: Patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis who receive maintenance therapy with rituximab are more likely to remain in remission than those given azathioprine, according to the results of the RITAZAREM trial.
The phase III study included 170 patients who experienced a relapse and then achieved remission during 4 months of induction therapy with rituximab and glucocorticoids. Participants were randomly assigned to receive maintenance treatment with rituximab 1000 mg every 4 months or azathioprine 2 mg/kg per day. Remission was defined as a Birmingham Vasculitis Activity Score for Wegener’s granulomatosis of 1 or lower and a glucocorticoid dose of no more than 10 mg/day.
As reported at the 2019 ACR/ARP Annual Meeting in Atlanta, Georgia, USA, participants in the rituximab group were significantly less likely than those given maintenance azathioprine to experience relapse over 24 months, with a hazard ratio of 0.30.
In all, 13% of the 85 patients given rituximab experienced a relapse, as did 38% of the 85 treated with azathioprine. Of the 11 relapses in the rituximab arm, 82% were classified as minor and 18% major; the corresponding proportions of minor and major relapses in the azathioprine group were 62% and 38%.
Moreover, the proportion of ANCA-negative patients increased from 36% at month 4 to 49% at month 24 in the rituximab group, but remained stable in the azathioprine arm, with 33% and 31% of patients achieving this endpoint at month 4 and month 24, respectively.
Presenting author Rona Smith, from the University of Cambridge in the UK, told the audience that there were “no new safety signals identified” in the RITAZAREM trial.
A total of 22% of patients given rituximab and 36% given azathioprine experienced severe adverse events. Rates of serious infection were 8% and 13%, respectively, and approximately 50% of patients in both groups experienced a non-serious infection over the course of the study. Hypogammaglobulinemia (immunoglobulin G<5 g/L) was reported in 29% and 25% of patients in the rituximab and azathioprine arms, respectively.
“Hypogammaglobulinemia is always a concern in patients treated with rituximab, particularly repeat dosing of rituximab,” said Smith.
When asked about the rationale behind the rituximab dosing schedule, she explained that “we wanted to achieve complete B-cell depletion for the duration of the treatment period,” and the dose was based on data showing that relapses tend to occur at months 5 and 6 of each cycle when rituximab is given every 6 months.
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