ERBB2 and cancer: Breast cancer (BC) accounts for approximately 15% of the total number of female malignant tumors, and is associated with high mortality.1 About 15%-20% of all BC cases exhibit overexpression of the human epidermal growth factor-2 (HER-2).2,3 Studies have shown that HER-2 positivity in BC is associated with worse prognosis and shorter overall survival.4,5 Therefore, identifying safe and effective treatment for patients with HER-2 positive BC is crucial.3–5