A Phase Ⅱ Trials of Sintilimab as Consolidation Therapy After Radical Concurrent Chemoradiotherapy in Locally Advanced Unresectable ESCC

Inclusion Criteria: 1\. Age 18-75 years old, both men and women; 2. Histology confirmed as esophageal squamous cell carcinoma; 3. T1bN+M0, T2-T4aN0-2M0 locally advanced stage； 4. Tissue samples should be provided for biomarker analysis, and the newly obtained tissues should be selected. Patients who cannot provide newly obtained tissues can provide 5-8. pieces of 5-um thick paraffin sections; 5. ECOG: 0\~1; 6. Expected survival period ≥ 12 weeks; 7. The main organs function normally, that is, the following criteria are met: 1. Blood routine examination: 1. HB≥90g/L; 2. ANC ≥ 1.5 × 109 / L; 3. PLT ≥ 80 × 109 / L; 2. Biochemical examination: 1. ALB ≥ 30g / L;b.ALT and AST ≤ 2.5ULN; if there is liver metastasis, ALT and AST ≤ 5ULN;c.TBIL ≤ 1.5ULN;d.plasma Cr ≤ 1.5ULN or creatinine clearance (CCr) ≥ 60ml / min; 8.Doppler ultrasound assessment: left ventricular ejection fraction (LVEF) ≥ normal low limit (50%); 9. Women of childbearing age should agree to use contraceptives (such as intrauterine devices, contraceptives or condoms) during the study period and within 6 months after the end of the study; negative serum or urine pregnancy test within 7 days prior to study enrollment And must be non-lactating patients; males should agree to patients who must use contraception during the study period and within 6 months after the end of the study period; 10. Subjects voluntarily joined the study, signed informed consent, and were well-adhered to follow-up. Exclusion Criteria: 1. Does not meet the above inclusion criteria; 2. Those who are allergic to or sensitive to capecitabine and cisplatin or metabolic disorders; 3. The patient has any active autoimmune disease or a history of autoimmune disease (such as the following, but not limited to: autoimmune hepatitis, interstitial pneumonia, uveitis, enteritis, hepatitis, pituitary inflammation, vasculitis, nephritis,Hyperthyroidism; patients with vitiligo ; Asthma has been completely relieved in childhood, and patients who do not need any intervention after adulthood can be included; asthma patients who require bronchodilators for medical intervention cannot be included); 4. The patient is using immunosuppressive agents or systemic hormonal therapy for immunosuppressive purposes (dose\> 10 mg/day of prednisone or other therapeutic hormones) and continues to be used for 2 weeks prior to enrollment; 5. contraindications to radiotherapy; 6. Patients with any severe and/or uncontrolled diseases:Patients with unsatisfactory blood pressure control (systolic blood pressure ≥150mmHg or diastolic blood pressure ≥100 mmHg); myocardial ischemia or myocardial infarction with grade I or above, arrhythmia (including QT interval ≥ 480ms) and grade I cardiac insufficiency; 7. Active or uncontrolled serious infections; 8. Liver diseases such as decompensated liver disease, active hepatitis B (HBV-DNA ≥ 104 copies/ml or 2000 IU/ml) or hepatitis C (positive hepatitis C antibody, and HCV-RNA is higher than the lower limit of detection of the analytical method); 9. Urine routine indicates that urine protein ≥ ++, and confirmed 24-hour urine protein quantitation\> 1.0g; 10. The patients whose imaging showed that the tumor had invaded the important vessels or the tumor was likely to invade the important vessels and cause fatal hemorrhage during the follow-up study; 11. Pregnant or lactating women; 12. Patients with other malignancies within 5 years (except for basal cell carcinoma and cervical carcinoma in situ) that have been cured; 13. Patients with a history of psychotropic substance abuse who are unable to quit or have a mental disorder; 14. Patients who have participated in other drug clinical trials within four weeks; 15. At the discretion of the investigator, there are patients with serious concomitant disease that compromises patient safety or affects the patient's completion of the study; 16. The investigator believes that it is not suitable for inclusion.