One example of such a therapeutically targeted biomarker is the anti-ERBB2 monoclonal antibody, trastuzumab (Herceptin®, Genentech), developed using multiple, diverse ERBB2-overexpressing breast cancer cell lines [13, 14], which is now a standard adjuvant therapy for ERBB2-positive breast cancer patients [15]. Here, ERBB2 is linked to breast cancer.