Whole exome sequencing analysis of the primary tumour biopsies before endocrine therapy and 12 hotspot HER2/ERBB2 mutations covering kinase, extracellular, transmembrane, and cytoplasmic domains resulted in detecting the HER2 alterations only in the metastatic biopsies but not the primary, suggesting that these alterations were acquired during the course of therapy [Figure 1]. This evidence concerns the gene ERBB2 and neoplasm.