Esophageal squamous cell carcinoma (ESCC) is a major subtype of esophageal cancers. The Five-year survival rate of ESCC is low and molecular targets for ESCC treatment and prognosis assessment are very limited. T cells are critical for clearance of cancer cells and blockade of co-inhibitory molecules for T cell activation has emerged as a promising therapy to treat cancer patients. However, in ESCC patients such co-inhibitory molecules regulating T cell activation is poorly documented.