Passive immunotherapeutic strategies in the management of breast cancer overexpressing HER2 include the use of trastuzumab (recombinant monoclonal humanized IgG1 HER2 blocker antibody) and, more recently, pertuzumab (recombinant monoclonal humanized IgG1 antibody that blocks HER2 receptor dimerization) and T-DM1 (trastuzumab emtansine conjugate). The gene discussed is ERBB2; the disease is breast cancer.