Humanized anti-HER2/neu mAb (Trastuzumab; Herceptin®; Genentech), used to treat HER2-positive metastatic breast cancer has been reported to possibly also target HER2-expressing cardiomyocytes, block all downstream signaling from HER2 and trigger congestive heart failure risk [170] or cardiac dysfunction in up to 4% patients with Transtuzumab monotherapy with higher incidence in patients receiving additional chemotherapy, such as anthracyclines [78, 129]. Here, ERBB2 is linked to congestive heart failure.