In recent years, CD4+ T cell (helper T cell) is drawing more attention in cancer immunotherapy area, as studies have shown that in infections or cancer, when non-self peptides or tumor-associated antigens are generated, interactions between the HLA-II–peptide complex on APCs and the TCR on CD4+ T cells, are key to initiate and sustain immune responses [5–7]. The gene discussed is CD4; the disease is cancer.