Efficacy and safety of Extended-Interval Rituximab vs. Standard MAINRITSAN Regimen for remission Maintenance in ANCA-Associated Vasculitis: A Multicenter Study

Background: Rituximab (RTX) achieved high remission-induction and sustained maintenance rates for patients with antineutrophil cytoplasmic antibody (ANCA)-associated vasculitis (AAV) [1,2]. However, RTX is an expensive medication, which may potentially lead to serious side effects. Defining the best dose regimen for maintenance in AAV is still an unmet need. Objectives: The aim of the present study is to compare the effects of extended interval of RTX (500 mg once per year) to standard MAINRITSAN regimen RTX (500 mg twice per year) as remission-maintenance therapy in AAV patients. Methods: We included consecutive AAV patients (classified as GPA and MPA) referring to four different Rheumatology centers in Italy. We assessed AAV patients who successfully achieved disease remission (BVASv3=0) with conventional RTX or others immunosuppressive regimens and have been subsequently treated with RTX for maintenance of remission. Maintenance regimens were classifies according to the timing of RTX administration, in the MAINRITSAN maintenance group (RTX 500-mg at six-month intervals) and thee Extended-Interval group (RTX 500 mg once a year). Some patients started maintenance with Extended-interval regimen, while others switched to the annual regimen during the course of standard six-monthly maintenance. After at least two consecutive infsione, we assessed the remission rate, damage, glucocorticoids intake, ANCA status, serum immunoglobulin levels, infections and deaths. Results: From October 2011 to October 2024, 100 AAV patients (median age 60 [54-70], 54% female, 97% ANCA positive, 67% anti PR3), 65 classified as GPA and 25 MPA, achieved complete disease remission with conventional RTX induction regimen. Between them 82 started maintenance with standard regimen and 18 with Extended- interval. Among MAINRITSAN group, 29 patients switched to 12-months scheme. No significant differences at baseline were noted between groups. At the end of observation period relapse rate, infection incidence and deaths were comparable between the two group. No differences were noted in remission maintenance, negative ANCA negativization and glucocorticoid discontinuation at last follow-up. Conclusions: Reduced exposure to RTX was not associated with an impaired efficacy of maintenance therapy in patients with AAV. Remission maintenance with extended-interval of RTX is a safe and more cost-effective option.