Among tumor-infiltrating T lymphocytes, CD8+ T cells, which are also called CTLs, are the predominant pillar that was responsible for the strong antitumor immune responses [47], while CD4+ T cells act as helper T cells, and can be divided into two types according to the level of Foxp3 markers, namely effective T cells (Teff, CD4+Foxp3−) and regulatory T cells (Tregs, CD4+Foxp3+) [48]. Here, CD4 is linked to neoplasm.