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.