CD4 and breast cancer: The treatment using intravenous tumor-primed CD4+ T cells with intraperitoneal administration of an α-GITR mAb can activate CD8+ T cells and increase the secretion of cytokines such as TNF-α, IL-4, and IL-5, which may inhibit tumor metastasis; the study showing these findings (NCT02583165, NCT02628574) is currently part of an ongoing phase I clinical trial on breast cancer and melanoma.