ERBB2 and breast cancer: Cancer is a major obstacle to increasing life expectancy and is one of the leading causes of death worldwide.1–3 Approximately 1 million cases of breast cancer are diagnosed globally each year, with over 170 000 classified as triple-negative breast cancer (TNBC).4 TNBC lacks estrogen and progesterone receptors and exhibits overexpression of HER2, and it overlaps with basal-like breast cancer.5–10 This subtype is associated with poor prognosis owing to its high recurrence rate, limited progression-free survival, and the absence of targeted therapies.