Reduced dose rituximab appears to be an effective option for maintenance therapy in ANCA associated vasculitis (AAV), a UK study shows.

The optimum dose, frequency and duration of maintenance rituximab was unclear, according to clinicians from Birmingham University.

The doses recommended by experts were either 1000mg or 500 mg every 6 months for two years, with the uncertainty possibly due to lack of direct comparison between different regimens, they wrote in their paper published in Rheumatology Advances in Practice.

The retrospective study included 62 patients with AAV who were categorised into four groups based on the dose of maintenance rituximab: 2000mg/year regime (regime A, n=16), 1000mg/6 months infusion (regime B, n=21 which included 8 patients who were switched to this regime after receiving ≥2 years of regime A), 1000mg/6 months followed by 500mg/6 months (regime C, n=27) and upfront 500mg/6 months rituximab (regime D, n=6).

During a minimum follow up of six months, the proportion of patients who relapsed (defined as a BVAS score of more than 1) and required escalation of steroid dose was significantly higher in regime A (43 relapses in 14 patients) compared to the other dosage groups.

Among four relapses observed in patients given regime C, three occurred while receiving 1000mg/6 monthly infusions and one patient relapsed while receiving extended maintenance 500mg/6 monthly rituximab. None of the patients in regimes B and D relapsed.

The median time to relapse was 38 months for patients receiving regime C and 12 months for those receiving regime A.

The rate of infection was 0.47 and 0.24 per patient per year in patients receiving regime A and D respectively. No infections were noted in patients receiving regime B and C. Serious infections requiring hospitalisation rates were 0.04 per patient per year (11 episodes in 8 patients) in patients on regime A, and 1 episode in 1 patient for regimes B and C. No serious infections were noted in patients receiving regime D.

The research team concluded: “500mg 6 monthly infusions appear to be an effective and safe option in maintenance of remission in AAV, either following previous 1g 6 monthly or 500mg 6 monthly from start of maintenance rituximab therapy.”

“This study provides real-world data to reiterate the effectiveness of reduced rituximab dose. Studies with longer follow up are required to confirm the observations,” they said.