Neoadjuvant PD-1 Blockade for Elderly Esophageal Squamous Cell Carcinoma (BLESS)

Inclusion Criteria: 1. Subjects signed the informed consent and volunteered to participate in the study. 2. Esophageal squamous cell carcinoma confirmed by histology or cytology. 3. Thoracic esophageal squamous cell carcinoma confirmed by CT or pet-CT, which is classified as T1N1-3M0 or T2-3N0-3M0 (M1 lymph node metastasis confined to the supraclavicular lymph nodes) (AJCC 8th). 4. Expect to have R0 resection 5. In age \>75. 6. ECOG PS: 0\~1. 7. Have not received any anti-tumor treatment for esophageal cancer in the past, including radiotherapy, chemotherapy, surgery, etc. 8. No contraindications to surgery. 9. Has sufficient organ function including (1) Blood routine: NE≥1.5×109/L; PLT≥100×109/L; HGB≥90 g/L (2)Comprehensive Metabolic Panel: bilirubin≤ 1.5×ULN; ALT≤2.5×ULN; AST≤2.5×ULN; sCr≤1.5×ULN or CrCl≥50 mL/min（Cocheroft-Gault) (3) Coagulation function: INR≤1.5. 10. Women of childbearing age must undergo a serological pregnancy test within 72 hrs before first administration. Women of childbearing age, or male subjects with childbearing age female partners, must take contraceptive measures from the first dose to five months after last administration. 11. Good compliance, willing to comply with follow-up schedules. Exclusion Criteria: 1.Subjects have received or are receiving any of: 1. anti-tumor interventions such as radiotherapy, chemotherapy, immunotherapy or other medictions. 2. Received systemic corticosteroid therapy (prednisone equivalence\> 10mg/d) or other immunosuppressive agents within the first 2 weeks prior to the first administration. 3. live vaccine within 4 weeks before the first administration. 2\. Cancer related exclusion criteria 1. other cancers instead of ESCC 2. non-recetable or metastatic ESCC 3. not comply with T1N1-3M0 or T2-3N0-3M0 (AJCC 8th). 4. Subjects with other malignant tumors within 5 years before the first administration, but subjects with cervical carcinoma in situ, skin basal cell carcinoma, skin squamous cell carcinoma, and localized prostate cancer received radical surgery in situ that have received radical treatment and do not need other treatment can be included). 3\. Other criteria Subjects have uncontrolled cardiovascular diseases, such as 1) heart failure ≥ NYHA class 2, 2) unstable angina 3) myocardial infarction within 1 year; 4) supraventricular or ventricular arrthymia that needs treatment Subjects with any known active autoimmune disease Pregnant or breastfeeding female Presence of allergy or hypersensitivity to investigational medications HIV positive or active hepatitis B (HbsAg positive and HBV-DNA ≥2000 IU/ml or ≥ 104 copies/mL) or active hepatitis C (HCV antibody positive) or active tuberculosis Investigators assessed there might be other factors that cause subjects to withdrawl.