Our exploratory data can be hypothesis-generating for further studies, as it will be interesting to verify how PAM50 subtypes or ERBB2 expression levels could impact treatment response (for instance in relation to the role of the HER2-targeted part of the ADCs in HER2-low tumors with higher ERBB2 expression, with a HER2-enriched PAM50 subtype or according to HR status) in these breast cancer subtypes [39]. This evidence concerns the gene ERBB2 and breast cancer.