In HER2 over-expressing breast cancer, anti-HER2 agents such as trastuzumab, drug–antibody conjugate (TDM-1), and TKIs (neratinib, lapatinib) have been shown to have activity in BMs.92–94,120,121 In addition, the role of high-dose HER2 targeting monoclonal antibodies has shown promise using trastuzumab and pertuzumab in the PATRICIA study.87 Lapatinib, a TKI-targeting HER2 and EGFR, shows CNS activity. The gene discussed is ERBB2; the disease is breast cancer.