Clinical Perspective: Antibody-drug conjugates for the treatment of HER2-positive breast cancer

Antibody-drug conjugates (ADCs) are a promising class of can- cer biopharmaceuticals that exploit the specificity of a mono- clonal antibody (mAb) to selectively deliver highly cytotoxic small molecules to targeted cancer cells, leading to an enhanced therapeutic index through increased antitumor activity and decreased off-target toxicity. ADCs hold great promise for the treatment of patients with human epidermal growth factor receptor 2 (HER2)-positive breast cancer after the approval and tremendous success of trastuzumab emtansine and trastuzu- mab deruxtecan, representing a turning point in both HER2- positive breast cancer treatment and ADC technology. Addi- tionally and importantly, a total of 29 ADC candidates are now being investigated in different stages of clinical develop- ment for the treatment of HER2-positive breast cancer. The purpose of this review is to provide an insight into the ADC field in cancer treatment and present a comprehensive overview of ADCs approved or under clinical investigation for the treat- ment of HER2-positive breast cancer.