[State of art and new perspectives in the induction regimen of ANCA-associated vasculitis with renal involvement: from histopathology to therapy]

Anti-neutrophil cytoplasmic antibodies (ANCA)-associated vasculitis (AAV) are rare autoimmune diseases characterised by medium and small vessels inflammation. Renal vasculitic involvement is one of the most severe manifestations, with high mortality in case of a delayed diagnosis and a significant impact on patients' long-term prognosis. Histological classifications and scores for the definition of renal involvement in AAV exist and correlate with the renal outcome. Current induction regimen consists of a high dose of glucocorticoids and immunosuppressive drugs: cyclophosphamide (CYC), rituximab (RTX) or a combination of both. RTX use is expanding thanks to randomised control trials suggesting its non-inferiority compared to the standard CYC therapy in general AAV and a better safety profile; its cost has also reduced thanks to the availability of biosimilars. However, the equivalence of RTX and CYC in patients with severe renal involvement is still debated. The quest for the ideal induction regimen in AAV is moving towards a more personalized approach: on the one hand, efforts are made to use already existing therapies in the most appropriate way; on the other, new insights into AAV pathogenesis has allowed the discovery of new targets, such as the complement factor C5a. Thanks to this new AAV management, renal outcome and overall survival has visibly improved. New studies are needed to reach a more personalized approach in the induction regimen of ANCA-associated glomerulonephritis and AAV in general.