Patients with HER2-positive BC generally demonstrate a robust therapeutic response to HER2-targeted therapies,6,7 encompassing monoclonal antibodies (eg, trastuzumab, pertuzumab), small-molecule tyrosine kinase inhibitors (TKIs) (eg, lapatinib, neratinib), and antibody-drug conjugates (ADCs) (eg, Trastuzumab deruxtecan, Trastuzumab emtansine).6,8 Conversely, HER2-low-expression refers to a level of HER2 protein expression that is intermediate between positive and totally negative, typically characterized by an IHC score of 1+ or 2+ with FISH negative. The gene discussed is ERBB2; the disease is breast cancer.