Efficacy and Safety for Rituximab Combined With Telitacicept in the Treatment of ANCA-associated Vasculitis (TTCAAVREM)

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 have severe active AAV according to the 2021 ACR/vasculitis foundation definition. 4. Patients have to be PR3-ANCA-positive at diagnosis or during the course of their disease. Exclusion Criteria: 1. Patients who had been treated with Rituximab but had to stop due to adverse events or intolerance. 2. Patients who had other autoimmune diseases. 3. 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). 4. Patients who are pregnant or have planned for pregnancy in next 2 years. 5. Patients with uncontrolled sever hypertension, diabetes, active bacteria or fungal infection. 6. Patients with active hepatitis virus infection as well as patients who have active mycobacteria infection. 7. Patients with malignancy. 8. Patients who are not eligible according to the judge of the principal investigators.