Conventional chemotherapy can stimulate the immune system against cancer in several ways, including directly activating CD4 positive, CD8 positive, or γδ T cells, leading to the production of chemokines and cytokines; inhibiting or depleting immunosuppressive myeloid-derived suppressor cells and regulatory T cells; and upregulating MHC class I expression on cancer cells [20]. This evidence concerns the gene CD4 and cancer.