MPO and anti-neutrophil cytoplasmic antibody-associated vasculitis: Myeloperoxidase (MPO) ANCAs are commonly associated with predominantly vasculitic features and kidney involvement in patients with ANCA-associated vasculitis (AAV).1 Advances in remission-induction treatment regimens resulted in significant survival improvements.2, , –5 However, it is important to determine which patients need maintenance immunosuppression, the optimal duration of therapy, and whether withdrawal of remission maintenance is possible without increasing the relapse risk.6, –8