ERBB2 and neoplasm: •Low to absent ER gene expression •High ERBB2 pathway genes expression including; ERBB2 and GRB7 •Intermediate expression of luminal-related genes and proteins (e.g., ESR1 and PR) and low expression of basal-related genes and proteins (e.g. keratin 5 and FOXC1) •Enriched with high frequency of APOBEC3B-associated mutations •1 out of 5 patients of HER2+/HR+ tumours will be identified as non-luminal