For example, bulk gene expression profiling of pre-treatment tissue samples has identified tumor characteristics (HER2-enriched intrinsic subtype, HER2 expression levels, ESR1 expression levels [20,21,22,23,24], and microenvironmental characteristics (increased immune infiltration [22,24,25,26,27]) that are linked to the response to HER2-targeted therapy in the neoadjuvant setting. Here, ERBB2 is linked to neoplasm.