Commonly used HER2 inhibitors include trastuzumab, patuzumab, lapatinib, pyrotinib, among others.[3] However, HER2 positive metastatic breast cancer progressively develop resistance to trastuzumab, and some of the HER2 overexpressed breast cancer receiving trastuzumab-adjuvant therapy eventually relapse. The gene discussed is ERBB2; the disease is breast carcinoma.