ERBB2 and breast cancer: The association of biological pathways to treatment response in HER2+ breast cancer patients has been conducted based on pathway enrichment analysis using individual genes identified either (1) based on higher activity in responders (or non-responders) versus non-responders (or responders) (Wu et al., 2012; Boulbes et al., 2015; Nam et al., 2015) or (2) as individual or multigene biomarkers of response (Harris et al., 2007; Willis et al., 2018).