However, during tumor immunity, T cells differentiate into exhausted CD8+ T cells, TEX, with gradual loss of cytokines, high expression of inhibitory markers (PD-1, Tim-3, LAG3, TIGIT, and 2B4), metabolic alterations, and decreased proliferative potential and viability in response to persistent antigenic stimulation (Sen et al., 2016). This evidence concerns the gene PDCD1 and neoplasm.