ERBB2 and breast cancer: Trastuzumab and Pertuzumab, two humanized monoclonal antibodies that target HER2, and Lapatinib, a reversible dual inhibitor of the HER1 and HER2 tyrosine kinase, are routinely used to treat patients with breast cancers that overexpress HER22, 3, 4, 5, 6, 7.