Antineutrophil cytoplasmic antibody (ANCA) vasculitis: pathophysiology, diagnosis, and the evolving treatment...

The antineutrophil cytoplasmic antibody (ANCA) vasculitides include several closely related, often severe, multisystem autoimmune diseases characterized by antibodies against serine proteinase 3 (PR3) or myeloperoxidase. Loss of tolerance to these antigens triggers a cascade of events, beginning with the priming of neutrophils by proinflammatory cytokines and complement activation, translocation of ANCA-specific antigens to the plasma membrane, neutrophil hyperactivation, and further activation of the alternative complement pathway, leading to tissue damage and the clinical manifestations of ANCA vasculitis. Due to the heterogeneity in presentation of these diseases, diagnosis is often substantially delayed, leading to poor outcomes. The current treatment pathway for most patients involves induction with cyclophosphamide or rituximab in combination with glucocorticoids, followed by a maintenance phase with rituximab, azathioprine, or methotrexate, during which time glucocorticoids are tapered. Current therapies are often effective in inducing and maintaining remission but are associated with a range of toxicities. Several new therapies are in development for ANCA vasculitis. Avacopan, an orally administered inhibitor of the complement fragment 5a (C5a) receptor, has been assessed in a phase 3 clinical trial and may play a role in reducing the cumulative glucocorticoid dose. Preliminary data suggest that cluster of differentiation (CD) 80 and CD86 blockade with abatacept may also have a role in the management of ANCA vasculitis. There is an unmet need for additional therapeutic options for patients with these diseases.