MAINRITSAN 3 – Rituximab maintenance therapy for ANCA vasculitis
The optimal duration of Rituximab maintenance therapy for ANCA vasculitis is not known. The French vasculitis group has just published an important article to help answer this question. In this MAINRITSAN-3 study (link), they randomised patients who had previously had 2 years of maintenance Rituximab and were in remission (disease was quiet) to continue Rituximab at at dose of 500mg every 6 months or receive placebo (no treatment). They found that relapse (disease recurrence) was less common in those patients continuing Rituximab (4%) compared with those who received placebo (24%). Continuing Rituximab was especially important in patients with PR3+ ANCA vasculitis who had a very high relapse rate of 40% when on placebo. There were slightly higher rates of serious infection and low gamma-globulin (antibody levels) in the Rituximab treated group.
This trial once again supports continuing maintenance therapy for 4 years rather than 2 years in ANCA vasculitis, particularly for PR3+ patients. In view of the RITAZAREM and Mainritsan-1 trials showing superiority of Rituximab over Azathioprine this would ideally be with Rituximab. Unfortunately we still don’t have PBS subsidised access for maintenance Rituximab in Australia and we will rely on compassionate supply (or azathioprine or methotrexate) until this is remedied.