ERBB2 and breast neoplasm: In gene-based approaches, mutation, amplification, or expression of individual genes with known association with HER2+ breast tumor biology was investigated as potential biomarkers of response to these therapies (Gomez et al., 2007; Bianchini et al., 2011; Dave et al., 2011; Loibl et al., 2014; Schneeweiss et al., 2014; Vici et al., 2014; Menyhárt et al., 2015).