Consolidation of Toripalimab and Capecitabine After Chemoradiotherapy in ESCC

Inclusion Criteria: 1. Histologically confirmed squamous cell carcinoma of the esophagus; 2. Locally advanced esophageal cancer classified as stage I-IVA (inoperable or patient declined surgery) or stage IVB thoracic esophageal cancer with supraclavicular lymph node metastasis only (AJCC 8th edition) prior to treatment; 3. Completion of definitive concurrent chemoradiotherapy without disease progression; radiotherapy dose of 50-50.4 Gy using conventional fractionation and IMRT technique; concurrent platinum- or taxane-based doublet chemotherapy during radiotherapy; ≤4 cycles of induction chemotherapy allowed prior to radiotherapy; PD-1/PD-L1 antibody therapy permitted during induction chemotherapy and radiotherapy; no adjuvant therapy received; 4. Enrollment window: within 1-42 days after completion of chemoradiotherapy; 5. Age 18-75 years; 6. Estimated life expectancy \>6 months; 7. Eastern Cooperative Oncology Group performance status ≤ 2; 8. The function of important organs meets the following requirements: a. white blood cell count (WBC) ≥3.5×109/L, absolute neutrophil count (ANC) ≥1.5×109/L; b. platelets ≥75×109/L; c. hemoglobin ≥9g/dL; d. serum albumin ≥2.8g/dL; e. total bilirubin ≤1.5×ULN, ALT, AST and/or AKP ≤2.5×ULN; f. serum creatinine ≤1.5×ULN or creatinine clearance rate \>60 mL/min; 9. Ability to understand the trial details and has provided written informed consent. Exclusion Criteria: 1. Patients who have received antitumor therapy (including adjuvant chemotherapy, surgery, immunotherapy, targeted therapy, etc.) after completion of chemoradiotherapy; 2. Stage IVb patients with metastasis to solid organs (e.g., liver, bone, lung, brain, adrenal gland, peritoneum, etc.) at initial diagnosis; 3. Known or suspected allergy to the investigational drug(s) or any agent related to the trial regimen; 4. Presence of esophageal fistula and/or esophageal hemorrhage prior to enrollment; 5. Disease progression after chemoradiotherapy; 6. ≥Grade 2 radiation pneumonitis prior to enrollment; 7. History of ≥ Grade 3 immune-related adverse events prior to enrollment; 8. Prior treatment with targeted drugs; 9. History of other malignant tumors besides esophageal cancer, except for non-melanoma skin cancer, carcinoma in situ of the cervix, papillary thyroid carcinoma, or cured early-stage prostate cancer; 10. Patients with severe cardiac, pulmonary, hepatic, or renal dysfunction, hematopoietic system diseases, cachexia, or other conditions that make them unfit for chemotherapy; 11. Female patients who are pregnant or breastfeeding; 12. Inability to provide informed consent due to psychological, familial, social, or other factors; 13. Presence of CTC grade ≥2 peripheral neuropathy; 14. Patients with a history of diabetes for more than 10 years and poorly controlled blood glucose levels; 15. History of autoimmune disease or autoimmune disorders (e.g., colitis, systemic lupus erythematosus, rheumatoid arthritis, uveitis, hypophysitis, hyperthyroidism; not limited to these diseases or syndromes), immunodeficiency history, including HIV positivity, or other acquired/congenital immunodeficiency disorders, or history of organ transplantation or allogeneic bone marrow transplantation; 16. History of interstitial lung disease or non-infectious pneumonia; 17. Active hepatitis B (HBV DNA ≥2000 IU/mL or 10⁴ copies/mL) or hepatitis C (HCV antibody positive with HCV-RNA above the lower limit of detection); 18. Any unstable condition that may jeopardize patient safety or compliance.