In addition, TIM-3 plays a significant role in the immune effects of T cells.100 Zhao et al. used immunohistochemistry to detect the expression levels of TIM-3 and PD-1 on CD8+ tumor-infiltrating lymphocytes (TILs) in ESCC and analyzed the relationship between clinicopathological features or clinical outcomes and TIM-3 expression.101 They found that positive TIM-3 expression was associated with PD-1 positivity and a high density of CD8+ TILs, which is an essential factor affecting RFS (relapse-free survival) and OS in ESCC. Here, PDCD1 is linked to esophageal squamous cell carcinoma.