Neonatal cancer is an issue of real urgency in oncology. Of the various therapeutic strategies used against this category of malignancy, immune-based therapies are the most promising, however the prevention of pediatric cancer has not yet become a reality. In this study, published on OncoImmunology, Giuseppina Barutello and coworkers applied a DNA vaccination strategy against Her2/neu (neu) in the framework of the pre-birth immunization in order to gauge whether maternal immunization can be used in neonatal cancer immune-prevention. Exploiting the BALB-neuT mouse model of autochthonous mammary carcinogenesis, the authors observed a significantly extended tumor-free and overall survival in BALB-neuT offspring born and fed by mothers vaccinated against neu, as compared to controls. Maternally derived anti-neu IgG were successfully transferred from mothers to newborns and were responsible for the protective effect. The vaccinated-mother’s offspring also developed an active immunity against neu as revealed by the presence of T-cell-mediated cytotoxicity against the neu immunodominant peptide. This active response was due to the milk transfer of immune-complexes formed between the neu extracellular domain, shed from vaccine-transfected muscle cells, and the anti-neu IgG induced by the vaccine. These findings show that maternal immunization has the potential to hamper mammary carcinogenesis in genetically predestinated offspring and to develop into applications against lethal neonatal cancer diseases for which powerful therapeutic options are currently unavailable.