Toripalimab Adjuvant Therapy in Subjects With Resected Esophageal Squamous Cell Carcinoma Who Achieved Pathological Complete Response (pCR)

Inclusion Criteria: * Stage II or III esophageal cancer with histologically confirmed predominant squamous cell carcinoma at initial diagnosis; * Subjects must complete preoperative neoadjuvant therapy (unlimited treatment regimen) before being assigned to treatment and then undergo surgery; * Subjects must undergo complete resection (R0), be surgically determined to be disease-free and have a negative margin on the resected specimen, defined as no viable tumor within 1 mm of the proximal, distal, or surrounding resection boundary; * Subjects must have no residual pathology, the primary tumor is pCR, and the pathology report of the resected lymph nodes is ypN0; * ECOG performance status of 0 or 1; * The laboratory test meet the following requirements: Bone marrow function: neutrophils ≥ 1.5×10(9)/L, platelets ≥ 100×10(9)/L, hemoglobin ≥ 90 g/L Liver function：Total bilirubin ≤ 1.5 x ULN；AST and ALT ≤ 3 x ULN Renal function：Cr ≤ 1.5 x ULN，Ccr ≥ 50 ml/min. Exclusion Criteria: * Subjects with stage M1 resectable disease； * Received treatments for resected esophageal cancer (e.g., immunotherapy , chemotherapy, targeted therapy, radiotherapy, or biologic therapy); * Known to be allergic, highly sensitive or intolerable to research-related drugs or excipient * In the past 5 years, there were other malignant tumors, melanoma skin cancer or ervical carcinoma in situ were excepted.