ERBB2 and breast cancer: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer because of the poor expression of estrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor 2 (HER2), and high ki-67 status [1]; this means there are a lack of targeted drug therapies compared with the other three subtypes: luminal A, luminal B, and HER2-type [2].