Since the development of trastuzumab, trastuzumab-resistance in tumours has been noted and trastuzumab has been combined with the cytotoxic drug DM1 to form trastuzumab emtansine (T-DM1), and it is commonly used in combination with other ERBB2-targeted therapies such as lapatinib and pertuzumab, or mTOR inhibitors such as everolimus, and work has been ongoing on understanding its mechanism of action [3]. The gene discussed is ERBB2; the disease is neoplasm.