Very promising approaches that combine the immunogenic properties of HER2 with immune agonizts, such as 4-1BB (CD137), biespecific T cell engagers, IL-2 fusion proteins to expand TILs populations, vaccination with HER2 peptides to increase its immunogenic potential, and adoptive therapies with chimeric antigen receptor T (CAR-T) cells against HER2 arise to the arena of BC therapy. The gene discussed is ERBB2; the disease is breast cancer.