CD4 and neoplasm: It is now clear that the vaccine-driven prevention of tumor onset and expansion rests on the coordinated action of multiple mechanisms, such as the activation of cytotoxic T lymphocytes (CTLs) and CD4+ T-helper (Th) cell, the release of interferon (IFN)-γ and the induction of a potent humoral immune response against a specific tumor associated antigen (TAA) and a strong immune memory [5,13,14,15], which are some of the features required of a prophylactic cancer vaccine.