Efficacy, Safety and Immunological Evaluation of Tofacitinib in the Treatment of Primary Sjogren's Syndrome

Inclusion Criteria: 1. Male or female \>18 years of age at screening visits 2. Patients meet the American-European Consensus Group 2002 classification criteria 3. The patient must be informed in writing of the consent to participate in the trial and the patient is expected to be able to comply with the requirements of the study follow-up plan and other protocols. 4. Dosing of antimalarials, prednisone or equivalent, cholinergic stimulants, and topical cyclosporine required to be stable for at least 4 weeks before screening and during study; maximum doses allowed: * Hydroxychloroquinone, 400 mg/day; * Prednisone, 10 mg/day Exclusion Criteria: Any subject meeting any of the following criteria should be excluded: 1. Laboratory abnormality: * Hb≤9 g/dl * Neutrophil \<1.0 x 109/l * lymphocyte\<0.5 x 109/l 2. Diagnosis of other autoimmune disease, or other sicca syndrome. 3. Use rituximab or other monoclonal antibodies within 6 months. 4. Received high doses of glucocorticoid (\>10 mg/d) within 1 month. 5. Serious complications: including heart failure (≥ New York Heart Association (NYHA) class III), renal insufficiency (creatinine clearance ≤ 30 ml/min), liver dysfunction (serum Alanine transaminase (ALT) or aspartate aminotransferase (AST) greater than three times the upper limit of normal, or total bilirubin greater than Normal upper limit) 6. Known allergies, hyperreactivity or intolerance of tofacitinib or its excipients. 7. Have a serious infection needing hospitalization (including but not limited to hepatitis, pneumonia, bacteremia, pyelonephritis, EB virus, tuberculosis infection), or use intravenous antibiotics to treat infection in 2 months before the enrollment. 8. Infection with HIV (HIV antibody positive serology) or hepatitis C (Hep C antibody positive serology). If seropositive, it is recommended to consult a doctor who has expertise in treating HIV or hepatitis C virus infection. 9. Any known history of malignancy in the past 5 years (except for non-melanoma skin cancer, non-melanoma skin cancer or cervical tumor without recurrence within 3 months after surgical cure prior to the first study preparation). 10. Uncontrolled mental or emotional disorders, including a history of drug and alcohol abuse over the past 3 years, may hinder the successful completion of the study. 11. Pregnant, lactating women (WCBP) are reluctant to use medically approved contraceptives during treatment and 12 months after treatment.