Rituximab for ANCA associated vasculitis maintenance

13/11/2022

The treatment and understanding of ANCA associated vasculitis (AAV) continues to evolve. I’m in the middle of watching an AAV session at the American College of Rheumatology 2022 meeting and felt inspired to share some  newer Rituximab related insights.

Firstly, as of September 2022, Rituximab now has an unrestricted listing under the PBS. This means that it can be accessed for the cost of a standard PBS script by clinicians and patients for both induction AND maintenance of AAV.

Which raises the question… how long to treat. In 2020 I posted about the MAINRITSAN 3 trial. This trial suggested that continuing Rituximab maintenance beyond 18 months reduced the chance of relapse, particularly for PR3+ patients. The message seemed therefore to be that 36 months is better than 18 months…. BUT….

… a recently presented combined analysis of the MAINRITSAN 1, 2 and 3 trials with long-term (out to 7 years) follow-up by the French Vasculitis Group has finessed the message. It seems that those patients who had 18 months (3 rounds of Rituximab 500mg infusions 6 months apart) of treatment had similar relapse rates (~25%) as those who had 36 months of treatment. The previous MAINRITSAN 3 trial finding was due to a smaller group of patients who hadn’t had the 3 fixed 6 monthly Rituximab treatments.

We also need to consider COVID-19 in decision making as Rituximab treated patients have more severe COVID infections.

So, where does this leave us? In my view:

  • For the majority of AAV patients, I typically suggest Rituximab for induction (initial) therapy. At the six month mark we start 18 months of Rituximab maintenance (3 x 6 monthly Rituximab 500mg infusions).
  • Then… a discussion about the risk/benefit of extending maintenance; This new data suggests that a further 18 months of Rituximab probably wont reduce the ~25% long term risk of relapse. In some cases, such as for patients with a particularly high relapse risk or for those who cannot tolerate a relapse, long-term therapy with Rituximab or another maintenance agent may still be appropriate.