In fact, numerous studies have established the role of PAM50 intrinsic subtype as a biomarker for HER2-positive BC in the neoadjuvant setting.[29–31] HER2-enriched and basal-like subtypes have been reported to be strong predictors of pCR in both single and dual anti-HER2 therapy groups.[32–34] However, some patients may fail to achieve pCR and those with residual disease at surgery stand a higher ROR and death,[35] so it is important to look into the residual disease for why and what to do. This evidence concerns the gene ERBB2 and breast cancer.