Numerous studies have shown that activated CD8+ T cells are the major players involved in anti-tumor immunity, and in a subset of tumors, cancer cells inhibit the activation of CD8+ cytotoxic T cells through the expression of ligands such as PD-L1 that bind to inhibitory checkpoints, which has been suggested to be an important mechanism of immune escape for cancer cells (42). This evidence concerns the gene CD8A and neoplasm.