Effect of Tofacitinib in Treating ANCA-associated Vasculitis

Inclusion Criteria: * Patients with active AAV met the criteria of 1990 ACR and 2012 Chapel Hill criteria * Age 18 to 75 years * Written informed consent obtained before taking part in the study Exclusion Criteria: * Severe AAV defined as potentially organ- or life-threatening disease (i.e. alveolar haemorrhage, heart failure caused by myocarditis or pericarditis, progressive neurological symptoms, deaf, blindness, et al.) * Serum creatinine\>120umol/L or proteinuria\>1.0g/d * Receipt of a JAKi therapy previously * Co-existence of another systemic autoimmune disease * Secondary vasculitis (following neoplastic disease, an infection or antithyroid drugs) * Malignancy or history of malignancy * Infection by HIV, HCV, HBV or tuberculosis- * Severe uncontrolled cardiovascular, pulmonary, liver, gastrointestinal, endocrine, hematological, neurological, or psychiatric diseases that are not related to systemic vasculitis * Allergic to JAKi * Blood dyscrasias including confirmed: Hemoglobin \<9 g/dL or Hematocrit \<30%; White blood cell count \<3.0 x 109/L; Absolute neutrophil count \<1.5 x 109/L; Platelet count \<100 x 109/L; Alanine transaminase or aspartate aminotransferase or total bilirubin\>1.5 upper normal limit; Estimated glomerular filtration rate\<60ml/min/1.73m2 * Incapacity or refusal to understand or sign the informed consent form. * Pregnancy, breastfeeding.