Conversion of Tislelizumab Combined With Chemotherapy in Unresectable Esophageal Squamous Cell Carcinoma

Inclusion Criteria:

1. Histologically confirmed esophageal squamous cell carcinoma;
2. Unresectable cT4a/N3(stage ⅣA) (AJCC 8 TNM classification);
3. Have a performance status of 0 or 1 on the ECOG Performance Scale;
4. Age 18-75 years old, both men and women;
5. Be willing and able to provide written informed consent/assent for the trial;
6. Demonstrate adequate organ function, all screening labs should be performed within 10days of treatment initiation;
7. Female subjects of childbearing potential should have a negative urine or serumpregnancy within 72 hours before receiving the study medication's first dose. If theurine test is positive or cannot be confirmed as unfavorable, a serum pregnancy testwill be required;
8. Be willing to provide tissue from a newly obtained core or excisional biopsy of atumor lesion through repeated biopsies. Newly acquired is defined as a specimenobtained up to 4 weeks (28 days) prior to initiation of treatment on Day 1. Subjectsfor whom newly-obtained samples cannot be provided (e.g. inaccessible or subjectsafety concern) may submit an archived specimen only upon agreement from the Sponsor.

Exclusion Criteria:

1. Prior therapy (operation, radiotherapy, immunotherapy, or chemotherapy) for esophagealcancer;
2. Ineligibility or contraindication for esophagectomy;
3. Has a diagnosis of immunodeficiency or is receiving chronic systemic steroid therapy (in dosing exceeding 10 mg daily of prednisone equivalent) or any other form ofimmunosuppressive therapy within 7 days prior to the first dose of study drug;
4. Has active autoimmune disease that has required systemic treatment in the past 2 years (i.e. with the use of disease-modifying agents, corticosteroids, or immunosuppressivedrugs);
5. Has severe hypersensitivity and adverse events (≥Grade 3) to any PD-1/PD-L1inhibitors.