ERBB2 and breast cancer: Therefore, bsAbs that target T-cells and commonly expressed breast cancer cell surface antigens such as HER2 (Sen et al., 2001), EGFR (Stamm et al., 2019), epithelial cell adhesion molecule (EpCAM) (Kubo et al., 2018), trophoblast cell-surface antigen 2 (Trop2) and carcinoembryonic antigen-related cell adhesion molecule 5 (CEACAM5) (Chang et al., 2017) have been developed to specifically target tumors expressing these markers.