In terms of tumor immune evasion, exosomes derived from PCa cells selectively decrease the level of natural killer group 2, member D (NKG2D), on natural killer and CD8 + T cells by expressing NKG2D ligands on their surfaces, impairing the killing effect of these cytotoxic cells and promoting PCa cell immune escape [40]. The gene discussed is CD8A; the disease is posterior cortical atrophy.