Research Progress of Antibody-Drug Conjugates for HER2 Low Expression Advanced Breast Cancer

Antibody-drug conjugates(ADCs), which consist of monoclonal antibodies with strong antigenic specificity, coupled with highly active cytotoxic agents(also referred to as “payloads”), represent a groundbreaking class of targeted oncological therapy. These conjugates are no longer limited to oncogenic driver human epidermal growth factor receptor 2(HER2) as a target. Other antigens, including human epidermal growth factor receptor 3(HER3), trophoblast cell surface antigen 2(Trop-2), and folate receptor ɑ(FRɑ), have recently emerged as tumor cell surface non-oncodriver gene targets for ADCs. At present, significant advancements have been achieved in the field of breast cancer due to the emergence of ADCs. Moreover, the identification of the prospective subtype "HER2-low" has redefined conventional classification of breast cancer, thereby revolutionizing the treatment approach for this disease. Exploration of new targets is critical to expand the fraction of patients who can benefit from ADCs. Furthermore, ADCs are showing promise in addressing HER2-low breast cancer cases. This article reviews the research progress in the application of ADCs in the treatment of advanced HER2-low breast cancer in recent years, and puts forward new prospects for the future treatment of HER2-low advanced breast cancer.