Triple-negative breast cancer (TNBC) is a highly aggressive subtype of breast cancer characterized by the absence of estrogen receptors (ER), progesterone receptors (PR), and HER2 receptors. Patients with TNBC have a significantly lower 5-year survival rate compared to other breast cancer types. Molecular studies have identified numerous genes overexpressed in TNBC, which could serve as potential targets for preventive vaccines. Most existing vaccines target advanced disease stages, where immune suppression hinders efficacy. Preliminary data show that peptide vaccines targeting overexpressed self-antigens in TNBC can elicit strong immune responses. A multivalent vaccine, incorporating epitopes from multiple overexpressed proteins has shown greater efficacy in animal models than single-antigen vaccines. This project will develop a multi-antigen vaccine targeting TOP2A, cyclin E2, and KIF15, all overexpressed in TNBC. The new vaccine will be tested in vivo in syngeneic transplantable and in orthotopic TNBC mouse models.