Efficacy and Safety for Telitacicept in the Remission Maintenance Treatment of ANCA-associated Vasculitis (TTCAZAREM)

Inclusion Criteria: 1. Patients age 18 to 65 years, both genders can be included. 2. Patients who are newly diagnosed or relapsing granulomatosis with polyangiitis or microscopic polyangiitis must fulfill the 2022 ACR/EULAR classification criteria of GPA or MPA. 3. Patients who are in complete remission after combined treatment with glucocorticoids and Rituximab. Remission is defined as a Birmingham Vasculitis Activity Score (BVAS version 3) of 0. And the daily dosage of prednisone are no more than 10mg (or equivalent). 4. Patients have to be ANCA-positive at diagnosis or during the course of their disease. Exclusion Criteria: 1. Patients with TPMT gene mutation. 2. Patients who had been treated with either AZA but relapsed in the past. 3. Patients who had been treated with either AZA but had to stop due to adverse events or intolerance. 4. Patients who have planned for pregnancy in next 1.5 years. 5. Patients with severe liver dysfunction(defined as the 2-folds elevation of normal upper limit or Child grade III), heart failure or ESRD(eGFR\<30ml/min). 6. Patients with uncontrolled sever hypertension, diabetes, active bacteria or fungal infection; 7. Patients with active hepatitis virus infection as well as patients who have active mycobacteria infection; 8. Patients who had other autoimmune diseases. 9. Patients with malignancy. 10. Patients who are not eligible according to the judge of the principal investigators or site investigators.