The goal of this clinical trial is to evaluate the efficacy and safety of tislelizumab in combination with chemotherapy as a neoadjuvant treatment for advanced endometrial cancer.

This is a multicenter, prospective, single-arm open-label study designed to enhance surgical R0 resection rate, reduce residual lesions, decrease distant metastasis and disease recurrence rates, and prolong the survival of patients with advanced endometrial cancer (stage III-IVb FIGO 2023) by neoadjuvant chemotherapy combined with tislelizumab.

Inclusion Criteria:

1. Voluntary participation and signed informed consent form;

2. Age ≥18 years;

3. Eastern Cooperative Oncology Group performance status 0-1;

4. The International Federation of Gynecology and Obstetrics (FIGO 2023) stage III-IVb of endometrial cancer;

5. Has not received any systematic anti-tumor treatment for advanced diseases in the past;

6. Have measurable disease according to RECIST v1.1 criteria;

7. Patients must meet the following criteria for laboratory tests to ensure adequate organ function:

   • ANC ≥1,500/mm3, or ≥1.5×109/L
   • Platelet count≥75,000/mm3 or 75 x 109/L
   • Hemoglobin≥9 g/dL or ≥5.6 mmol/L
   • Glomerular filtration rate estimated（eGFR） according to the Chronic Kidney Disease Epidemiology Collaborative Group formula （CKD-EPI EQ6）was≥40 mL/ 1.73m2
   • Serum total bilirubin ≤ 1.5x upper limit of normal range（ULN）
   • Both AST and ALT were ≤3 x ULN

8. The expected lifespan exceeds 3 months.

Exclusion Criteria:

1. Received PD-1 target therapy other than tislelizumab or other antibody or drug therapy that specifically targets T-cell costimulation or checkpoint channels within 6 months before enrollment；
2. Has human immunodeficiency virus infection, active viral hepatitis, and active tuberculosis infection；
3. Active leptomeningeal disease or uncontrolled, untreated brain metastases resulting in elevated intracranial pressure;
4. Major surgical procedures had been performed within 4 weeks before consent was obtained；
5. Other conditions deemed by the investigator to be ineligible for enrollment.