The introduction and approval of a growing array of anti-HER2 drugs, including anti-HER2 antibodies (trastuzumab, pertuzumab), TKIs (lapatinib, pyrotinib, neratinib), and ADCs (Trastuzumab-emtansine, Trastuzumab deruxtecan), in recent years have substantially transformed the treatment landscape for HER2-positive breast cancer, leading to improved outcomes. The gene discussed is ERBB2; the disease is breast cancer.