Given that microtubule inhibitor (e.g., taxane)-based regimens with trastuzumab and pertuzumab are commonly used in the treatment of HER2+ breast cancer, targeting a unique HER2 epitope and delivering a DNA damaging cytotoxic agent were prioritized, allowing potential combination with, as well as minimizing cross-resistance to current treatment regimens. This evidence concerns the gene ERBB2 and breast cancer.