TIGIT, mainly expressed on exhausted CD8+ T cells, Tregs, and NK cells, interacts with a specific ligand on tumor cells, transmitting inhibitory signals through Immunoreceptor Tyrosine-based Inhibitory Motifs (ITIM) and Immunoreceptor Tyrosine-based Transferase (ITT) motifs [154]. This evidence concerns the gene CD8A and neoplasm.