A Study of IO Plus Radiotherapy in Patients With Advanced ESCC.

Inclusion criteria

• Age 18-80, had an Eastern Cooperative Oncology Group performance status score of 0-1;
• Patients had unresectable or recurrent esophageal squamous cell carcinoma that precluded esophagectomy or definitive chemoradiation, or distant metastatic disease;
• Patients had received no previous systemic therapy (patients who had progressed ≥6 months after [neo]adjuvant therapy or definitive chemoradiation were eligible);
• Patients accepted at least one cycle of anti-PD-1 immunotherapy combined chemotherapy as 1st line treatment.
• All lesions of current diagnosis did not receive local treatment such as radiotherapy, surgery, radiofrequency ablation before enrollment.
• The measurable lesion was determined by the investigator based on the RECIST 1.1 assessment. A lesion located in a previous radiotherapy area can be considered a target lesion if it is confirmed to progress and is considered to be measurable according to RECIST 1.1.
• Estimated survival time >12 weeks.
• The function of vital organs meets the following requirements:

Neutrophil absolute count (ANC) ≥ 1.5 × 10^9 / L platelets ≥ 100 × 10^9 / L; Hemoglobin ≥ 9g / dL; serum albumin ≥ 2.8g / dL; Total bilirubin ≤ 1.5 × ULN, ALT, AST and / or AKP ≤ 2.5 × ULN; if there is liver metastasis, ALT and / or AST ≤ 5 × ULN; if there is liver metastasis or bone metastasis AKP ≤ 5 × ULN; serum creatinine ≤ 1.5 × ULN or creatinine clearance > 60 mL / min; For patients with pulmonary lesions or previous lung irradiation who are known or suspected to have impaired lung function, the forced expiratory volume (FEV1) for 1 second of lung function must be above 1L.

• Female subjects of childbearing age must have a negative urine or serum pregnancy test within 72 hours prior to randomization. Subjects agreed to adequate contraception during the trial.
• The patient is voluntarily enrolled and obtained the informed consent form signed by the patient or his legal representative.

Exclusion criteria

• Patients who are prior exposure to immune-mediated therapy.
• Patients participated in any investigational drug study within 4 weeks preceding the start of treatment.
• The toxicity of previous anti-tumor treatment has not recovered to ≤ National Cancer Institute Common Terminology Criteria for Adverse Events (CTCAE) v5.0 level 1 (except for hair loss) or the level specified by the inclusion/exclusion criteria.
• Patients with uncontrolled brain metastases, or vertebral body metastasis with spinal cord compression symptoms.
• Patients with uncontrolled pleural, pericardial or pelvic effusion that requires repeated drainage.
• Patients with history of immunodeficiency, or severe medical diseases that are not well controlled, which may have effect on the treatment of this study.
• Any other malignant tumor was diagnosed within 5 years prior to or after the diagnosis of ESCC, except for malignant tumors with a low risk of metastasis and death (5-year survival rate >90%), such as well-treated basal cells or squamous cell skin cancer or cervical cancer in situ.