CD4 and neoplasm: In vivo studies have demonstrated that both innate and adaptive immune cells are essential for the anti-tumor activity of trastuzumab, involving NK cells, CD8αα + dendritic cells (DCs), adaptive CD8αβ + T cells, Type 1 CD4 + T helper (CD4 + Th1), and type I and II interferons as key players [11, 12].