A Phase 3, Open-label, Uncontrolled Single-arm Study to Evaluate the Efficacy, Pharmacokinetics, and Safety of Avacopan in Combination With a Rituximab or a Cyclophosphamide-containing Regimen in Children From 6 Years to < 18 Years of Age With Active ANCA-associated Vasculitis (AAV)

Inclusion Criteria: * Male and female children and adolescents from 6 to \< 18 years of age * Clinical diagnosis of granulomatosis with polyangiitis (GPA) or microscopic polyangiitis (MPA), consistent with Chapel-Hill Consensus Conference definitions (Jennette et al, 2013) * Newly diagnosed or relapsed AAV with positive test for anti-PR3 or anti-MPO antibodies * At least 1 PVAS major item, at least 3 PVAS nonmajor items, or at least the 2 renal items of proteinuria and hematuria. * eGFR \> 15 mL/min/1.73 m2 (using modified Schwartz equation per central lab guidelines) * Participants must have…