Study of Durvalumab Versus Placebo in Combination With Definitive Chemoradiation Therapy in Patient With ESCC

Inclusion Criteria: * 18 years or older at the time of signing the ICF. * Histologically or cytologically confirmed esophageal squamous cell carcinoma, and present with locally advanced disease (Stage II-IVA). * Unresectable or refusing surgery, and has been deemed suitable for definitive chemoradiation therapy. * Patients with at least an evaluable lesion per RECIST 1.1. * Mandatory provision of available tumor tissue for PD-L1 expression analysis. * ECOG PS 0 or 1. * Adequate organ and marrow function. * Life expectancy of more than 3 months. Exclusion Criteria: * Histologically or cytologically confirmed small cell esophageal carcinoma, esophageal adenocarcinoma or other mixed carcinoma. * Prior anti-cancer treatment for ESCC. * Patient with a great risk of perforation and massive bleeding. * History of allogeneic organ transplantation. * Active or prior documented autoimmune or inflammatory disorders. * Uncontrolled intercurrent illness. * History of another primary malignancy. * Active infection including tuberculosis, hepatitis B, hepatitis C, or human immunodeficiency virus. * Known allergy or hypersensitivity to any of the study drugs or any of the study drug excipients.