Inclusion Criteria

1. Aged 18 to 70 years inclusive.
2. The disease duration (from the date of diagnosis) prior to screening shall be at least 24 weeks and no more than 5 years..
3. The EULAR Sjögren's Syndrome Disease Activity Index (ESSDAI) score at screening is ≥ 5.
4. At screening, the stimulated whole salivary flow (SWSF) ≥ 0.05 mL/min OR unstimulated whole salivary flow (UWSF) ≥ 0.01 mL/min.
5. Positive for anti-Sjögren's-syndrome-related antigen A (anti-SSA/Ro) antibodies at screening.
6. Stable treatment regimen that can be continued until the end of study treatment (Week 48).
7. Women of childbearing potential (WOCBP) must agree to use a highly effective method of contraception correctly during the study treatment period and for 1 month (28 days) after the last dose.
8. Male participants with a WOCBP partner must agree to use protocol-specified contraceptive methods during the study treatment period and for 3 days after the last dose.

Exclusion Criteria

1. SjS secondary to other systemic autoimmune diseases (e.g., rheumatoid arthritis, systemic lupus erythematosus, or systemic sclerosis).
2. Other autoimmune or inflammatory diseases that could interfere with the assessment of treatment response in SjS.
3. Presence of any other medical condition associated with SjS symptoms.
4. Participants with a history of any clinically significant disease other than pSjS.
5. Significant ECG abnormalities at screening requiring treatment.
6. Participants with gastrointestinal diseases or gastrointestinal surgery present within 3 months prior to the screening visit that could affect the absorption of the study drug.
7. Current or past history of bleeding disorders or diseases related to platelet dysfunction.
8. Severe infection (bacterial, fungal, or viral) requiring hospitalization within 60 days prior to screening.
9. Participants with any uncontrolled clinically significant laboratory abnormality that, in the opinion of the investigator, could affect the interpretation of study data or the participant's participation in the study.
10. Participants considered by the investigator to be unsuitable for participation in this study for any reason.