It is worth noting that tumor-derived exosomes produced by external stress, such as heat shock, chemotherapeutic drugs, and irradiation, in lung carcinoma, hepatocellular carcinoma, and breast cancer, can induce various anti-cancer immune systems (activation of Th1, CD8+ T cells, and/or NK cells), which, in turn, are useful as immunotherapeutic vaccine candidates [10,11,12]. Here, CD8A is linked to cancer.