Overexpression of human epidermal growth factor receptor (HER)-2 is found in a
variety of cancers, often portending poor clinical outcomes. Therefore, HER2 is an attractive
target for treatment. This review describes the research progress of HER2 targeted inhibitors
in recent years. Excellent reviews are available, so we focus on the development, mechanisms
of action, and structure-activity relationships of different types of inhibitors, including
monoclonal antibodies, small molecule inhibitors, and antibody-drug conjugates (ADCs). In
addition, the differences among them are compared.