Trastuzumab was the first targeted therapy for use in women with metastatic breast cancer who have tumors that overexpress HER2,5 whereas imatinib was approved for the treatment of chronic myelogenous leukemia and is the first selective inhibitor of the Abl kinase.6 These notable successes validated the use of a tumor’s genetic makeup to guide the development and clinical use of targeted therapies and provided impetus for the cancer genomics revolution. The gene discussed is ERBB2; the disease is cancer.