Rituximab in relapsing and de novo MPO ANCA-associated vasculitis with severe renal involvement: a case series.

Background: Antineutrophil cytoplasmic antibody associated vasculitis (AAV) is a group of diseases associated in most cases with the presence of anti-neutrophil cytoplasmic antibodies (ANCAs). Rituximab- based remission induction has been proven effective in ANCA associated vasculitis but scarce data exist in forms with severe renal involvement. In this case series, we report the outcomes in patients with de novo or recurrent MPO-AAV and severe renal involvement treated with rituximab without cyclophosphamide (CYC).

Methods: In this single centre retrospective study, we analysed patients with a clinical diagnosis of de novo or recurrent AAV who met the following criteria: detection of P-ANCA, creatinine clearance lower than 30 ml/min, induction of remission therapy with rituximab without concomitant CYC and a follow up period of at least 6 months. The primary outcomes were complete remission after induction therapy, renal function recovery and mortality after the induction treatment.

Results: Eight patients met the inclusion criteria. The M:F ratio was 1:7, the average age was 54 years old and the median follow up was 10 months (7-72); in 2 patients there was a MPA renal limited vasculitis. A renal biopsy was performed in 7 patients. The median BVAS score at rituximab induction was 14(range 6-21). Two patients required haemodialysis before the induction treatment. Four patients developed end stage renal disease (ESRD) that required haemodialysis. These data show a remission of the disease, associated with a stabilization of the kidney function in 50% of patients. In 3 patients who did not show a response, there was also no response to CYC.

Conclusions: This study shows a partial efficacy of rituximab in renal function recovery and a low risk of infectious complications in patients with MPO vasculitis with severe renal involvement, in particular in the short term. The optimal treatment in this subgroup of patients still has to be established because data are lacking.