CD4 and neoplasm: CD4+ T cells that infiltrate advanced solid tumors consist of different effector cells, such as Th1, Th2, Th17, Tfh or regulatory T cells (Tregs), with distinct impact on anti-tumor immunity, immune escape, angiogenesis and metastasis [2, 4, 29], but the influence of the tumors on CD4+ effector T cell differentiation remains incompletely understood.