Medford et al. monitored the plasma genotypes in 143 women with endocrine-resistant MBC, and found that patients whose extracorporeal circulating tumor cells (CTCs) had HER2 mutations were highly sensitive to neratinib therapy(Medford et al. 2019).Cocco et al.(Cocco et al. 2018) found that D769Y and D769H were the most common somatic mutations of HER2; the tumor tissues of patients with D769Y mutations were used to establish mouse tumor xenograft models, which were treated with trastuzumab, lapatinib, or neratinib. The gene discussed is ERBB2; the disease is neoplasm.