Therapeutic Effect of Upadacitinib in Primary Sjögren's Syndrome

Inclusion Criteria:

1. Male or female >18 years of age at screening visits

2. Participants with diagnosis of pSS according to the 2016 ACR/EULAR criteria

3. Participants have an ESSDAI score ≥ 5

4. Participants must be on a stable dose of prednisone (≤10mg/day), antimalarials orequivalent, and cholinergic stimulants prior to Baseline.

5. Participants previously on other immunosuppressive drugs (methotrexate,azathioprine, mycophenolate mofetil, cyclosporine, tacrolimus, iguratimod) shouldhave withdrawn drug for at least 8 weeks (56 days) at the time of screening

6. If the subject has evidence of new latent tuberculosis (TB) infection, the subjectmust initiate and complete a minimum of 2 weeks (or per local guidelines, whicheveris longer) of an ongoing TB prophylaxis before continuing to receive the study drug.

7. If female, the subject must be postmenopausal, OR permanently surgically sterile, ORfor women of childbearing potential practicing at least one protocol-specifiedmethod of birth control, that is effective from Study Day 1 through at least 30 daysafter the last dose of study drug.

8. The patient must be informed in writing of the consent to participate in the trialand the patient is expected to be able to comply with the requirements of the studyfollow-up plan and other protocols.

Exclusion Criteria:

Any subject meeting any of the following criteria should be excluded:

1. Pregnant or breastfeeding female.

2. Diagnosis of other autoimmune disease, or other sicca syndrome.

3. Laboratory value abnormality:

(1)Serum aspartate transaminase (AST) or alanine transaminase (ALT) > 3.0 × upper limit of normal (ULN); (2)Estimated glomerular filtration rate by simplified 4-variable Modification of Diet in Renal Disease (MDRD) formula < 40 mL/min/1.73m^2; (3)Total white blood cell count (WBC) < 2,000/μL; (4)Absolute neutrophil count (ANC) < 1,000/μL; (5)Platelet count < 50,000/μL; (6)Absolute lymphocytes count < 500/μL; (7)Hemoglobin < 8 g/dL.

4. Ongoing infections at Week 0 that have not been successfully treated.

5. Infection with HIV ( HIV antibody positive serological test ) or hepatitis C (hepatitis C antibody positive serological test ). If the serum reaction is positive,it is recommended to consult a doctor with expertise in the treatment of HIV orhepatitis C virus infection.

6. History of any known malignancy in the last 5 years (except non-melanoma skincancer, non-melanoma skin cancer or cervical tumors that have not recurred within 3months after surgical cure prior to screening).

7. Underlying cardiac, pulmonary, metabolic, renal, hepatic, gastrointestinal,hematological or neurological conditions, chronic or latent infectious diseases, orimmune deficiency which places the patient at an unacceptable risk for participationin the study.

8. Prior exposure to any Janus kinase (JAK) inhibitor (including but not limited totocilizumab, sirukumab, sarilumab, upadacitinib, tofacitinib, baricitinib,ruxolitinib, peficitinib, and filgotinib).

9. Exposure to biological DMARDs in two months before screening.

10. Enrollment in another interventional clinical study while participating in thisstudy.

11. Consideration by the investigator, for any reason, that the subject is an unsuitablecandidate to receive the study drug.