Clinical Research Directory

Inclusion Criteria： * Age ≥18 and ≤75 years. * Diagnosis of Sjögren's syndrome per 2016 ACR/EULAR classification criteria. * Duration of Sjögren's syndrome diagnosis ≤7.5 years. * Serum anti-Ro/SSA (Ro60 and/or Ro52) positive. * Stimulated whole saliva flow rate ≥0.05 mL/min at screening. * Baseline ESSDAI score ≥5 in ≥1 of the following domains: systemic, lymphadenopathy, glandular, articular, cutaneous, renal, hematologic, biological. * Stable background therapy (hydroxychloroquine ≤400 mg/day, methotrexate ≤25 mg/week, or azathioprine ≤150 mg/day) for ≥12 weeks with stable dose ≥8 weeks prior to randomization. * Stable oral corticosteroid dose (≤10 mg/day prednisone equivalent) for ≥4 weeks prior to randomization. Exclusion Criteria： * Known hypersensitivity to IBI355 or its excipients. * Pregnancy or breastfeeding. * Uncontrolled interstitial lung disease (ILD) associated with Sjögren's syndrome (e.g., FVC \<70% predicted, ClinESSDAI pulmonary domain indicating severe activity, or NYHA Class III/IV dyspnea). * Active or untreated latent tuberculosis (IGRA-positive without ≥1 month prophylactic treatment). * Chronic hepatitis B (HBsAg+), hepatitis C (HCV RNA+), HIV, or syphilis. * Prior use of rituximab, other anti-CD20 agents, or other biologics targeting CD40/CD40L, BAFF/APRIL, or CTLA-4 within 6 months prior to randomization. * Use of JAK/TYK inhibitors within 8 weeks prior to randomization.