This study is aimed to evaluate the efficacy and safety of different doses of radiotherapy combined with sintilimab in locally advanced esophageal squamous cell carcinoma.

This study was designed as a two cohorts, phase II trial. Subjects will receive different doses of radiotherapy combined with sintilimab. The primary endpoint is progression-free survival.

Inclusion Criteria:

• ≥18 years old
• Histopathological examination of the primary biopsy confirmed the diagnosis of locally advanced esophageal squamous cell carcinoma
• At least one measurable lesion
• Eastern cooperative oncology group (ECOG) performance status of 0 to 1
• With adequate organs function

Exclusion Criteria:

• Patients with active malignancy within 5 years other than the tumor studied in this study or a localized tumor that has been cured such as resected basal or squamous cell carcinoma, superficial bladder cancer, cervical carcinoma in situ, or breast cancer
• Patients who have a higher risk of bleeding or perforation due to the tumor's obvious invasion of the adjacent organs (aorta or trachea) of the esophageal lesion, or patients who have formed a fistula
• Patients who have received any anti-tumor therapy for the research disease in the past, including radiotherapy, chemotherapy, immunotherapy (including but not limited to interleukin, interferon, thymus hormone) and traditional Chinese medicine therapy