HER2 overexpression in cancer is linked to rapid progression and poor prognosis.1 37 38 Despite availability of several HER2-targeted therapies, including mAbs, antibody-drug conjugates (ADCs) and tyrosine kinase inhibitors (eg, lapatinib), lack of therapeutic response in patients due to intrinsic or acquired resistance is commonly observed.3, 5 In many cases of intrinsic or acquired Tras resistance, tumors retain some cell-surface HER2 expression.4 The gene discussed is ERBB2; the disease is cancer.