ERBB2 and breast cancer: Although anthracyclines dominated the literature and clinical concern for cardiac toxicity of antineoplastic therapy for many years, the now-widespread use of trastuzumab—a monoclonal antibody directed against HER2/ErbB2 receptors—for the treatment of breast cancers that overexpressed HER2/ErbB2 revealed an overlapping but distinct phenotype of cardiac toxicity25.