Granulomatosis with polyangiitis and microscopic polyangiitis are small vessel vasculitides characterized by circulating antineutrophil circulating antibodies. Standard treatment for active severe disease has consisted of cyclophosphamide with glucocorticoids with or without plasmapheresis, which achieves approximately 75% sustained remission, but carries significant adverse effects such as malignancy, infertility, leukopenia, and infections. The role of B cells in the pathogenesis of anti-neutrophil circulating antibodies-associated vasculitis has been established, and as such, rituximab, a monoclonal anti-CD20 antibody, has been studied in treatment of active granulomatosis with polyangiitis and microscopic polyangiitis (induction) and in maintaining remission. Rituximab has been shown to be effective in inducing remission in several retrospective studies in patients with refractory disease or cyclophosphamide intolerance. The RAVE and RITUXVAS trials demonstrated rituximab is a noninferior alternative to standard cyclophosphamide-based therapy; however, its role in elderly patients and patients with severe renal disease warrants further investigation. Rituximab has been compared with azathioprine for maintaining remission in the MAINRITSAN trial and may be more efficacious in maintaining remission in patients treated with cyclophosphamide induction. Rituximab is not without risks and carries a similar adverse event risk rate as cyclophosphamide in randomized control trials. However, its use can be considered over cyclophosphamide in patients who have relapsing or refractory disease or in young patients seeking to preserve fertility.
Keywords: ANCA-associated vasculitis; GPA; MPA; induction therapy; maintenance therapy; rituximab.