Blood test may help some ANCA patients skip unnecessary drugs

Copied word for word from the study's registry entry, so the wording is the study team's rather than ours.

Inclusion Criteria: * Patients 18-85 years old. * ANCA Glomerulonephritis (GN) or vasculitis per Chapel Hill Consensus Criteria, with documented current or previously positive Myeloperoxidase (MPO)- or Proteinase 3 (PR3)-ANCA by ELISA test. Patients with biopsy-proven, pauci-immune crescentic glomerulonephritis are eligible if they have a positive ANCA test by immunofluorescent microscopy (IIFM). * Patients must be in complete remission for at least 1 month and after AT LEAST 3 MONTHS of induction of therapy with corticosteroids and rituximab (either 1000 mg IV x 2 or 375 mg/m2 IV x 4) OR corticosteroids and cyclophosphamide (monthly IV or daily oral doses). They must be on no more than 5 mg daily of oral prednisone or equivalent. Complete remission is defined as a Birmingham Vasculitis Activity Score (BVAS) score = 0. * Patients may be ANCA negative or positive at randomization. * B cells are not depleted anymore: B cell recovery reaches 1% CD19+ B cells (enough to allow determination of CD5+ B cells with confidence). Exclusion Criteria: * Patients who have had ≥ 2 relapses (defined as recurrence of any signs or symptoms attributable to active vasculitis) previously as patients with multiple prior relapses may be at higher risk of future relapse and require maintenance therapy * Patients with persistent low-grade disease activity ("grumbling" disease defined as BVAS \> 0 and ≤ 3) * Patients with active systemic infections or deep space infections within the 3 months prior to screening. * Patients participating in another clinical trial mandating maintenance therapy * Patients with drug-induced ANCA vasculitis (e.g. levamisole-adulterated cocaine) * Active tuberculosis, human immunodeficiency virus (HIV), hepatitis C virus or hepatitis B virus infections * For women of child-bearing potential, pregnancy, breastfeeding, unwillingness or inability to comply with effective contraception * Inability to come to scheduled visits