ERBB2 and breast cancer: In contrast to the promising clinical benefits, such as trastuzumab deruxtecan (T-DXd) for the treatment of HER2 (human epidermal growth factor receptor 2)-positive breast cancers and other types of HER2-positive unresectable or metastatic solid cancers [8,9,10], many FDA-approved ADCs have relatively modest efficacy and can cause severe toxicity [3,11].