Avacopan vs Reduced-dose Glucocorticoids in ANCA-associated Vasculitis

Inclusion Criteria: 1. Provision of written informed consent by a patient or a surrogate decision maker 2. Age=\>18 years 3. New clinical diagnosis of ANCA-associated vasculitis (granulomatosis with polyangiitis, microscopic polyangiitis) consistent with the 2012 Chapel Hill consensus definitions and 2022 EULAR/ACR classification criteria 4. Positive test by ELISA, CLEIA or FEIA for proteinase 3-ANCA or myeloperoxidase-ANCA Exclusion Criteria: 1. Prior treatment for ANCA-associated vasculitis before trial entry 2. ANCA-associated vasculitis related glomerulonephritis (eGFR less than 15ml/min) or alveolar hemorrhage (oxygen inhalation more than 2L/min) 3. Presence of another multisystem autoimmune disease 4. Known infection with HIV; a past or current history of hepatitis B virus or hepatitis C virus infection 5. Desire to bear children, pregnancy or lactating 6. History of malignancy within the past 5 years or any evidence of persistent malignancy 7. Ongoing or recent (last 1 year) evidence of active tuberculosis 8. History of severe allergy or anaphylaxis to monoclonal antibody therapy 9. Any concomitant condition anticipated to likely require oral systemic glucocorticoids, immunosuppressants, biologics, plasma exchange or IVIg 10. Any biological B cell depleting agent (such as rituximab or belimumab)-use within the past 6 months 11. Past history of medication of avacopan 12. Patients can not take avacopan and prednisolone orally 13. Other conditions, in the investigator\'s opinion, inappropriate for the trial entry