Study to Evaluate Avacopan in Combination With a Rituximab or Cyclophosphamide-containing Regimen, in Children From 6 Years to < 18 Years of Age With AAV.

Inclusion Criteria:

• Male and female children and adolescents from 6 to < 18 years of age

• Clinical diagnosis of granulomatosis with polyangiitis (GPA) or microscopicpolyangiitis (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-MPOantibodies

• At least 1 PVAS major item, at least 3 PVAS nonmajor items, or at least the 2 renalitems of proteinuria and hematuria.

• eGFR > 15 mL/min/1.73 m2 (using modified Schwartz equation per central labguidelines)

• Participants must have a bodyweight of ≥ 15 kg at day 1.

Exclusion Criteria:

• Any other known multisystem autoimmune disease including eosinophilic granulomatosiswith polyangiitis (Churg-Strauss), systemic lupus erythematosus , IgA vasculitis (Henoch-Schönlein), rheumatoid vasculitis, Sjogren's syndrome, anti-glomerularbasement membrane disease, or cryoglobulinemic vasculitis

• Alveolar hemorrhage requiring invasive pulmonary ventilation support anticipated tolast beyond the screening period of the study

• Any medical condition requiring or expected to require continued use ofimmunosuppressive treatments, including corticosteroids that may cause confoundmentwith study assessments and study conclusions.