The novel agents being tested for the treatment of HER2-low BC patients are categorized as ADCs deploying anti-HER2 epitopes in their monoclonal antibody component, though with different cytotoxic warheads than trastuzumab–emtansine, and a bi-specific antibody targeting HER2 and HER3 [46,47,48,49]. Here, ERBB2 is linked to breast cancer.