In addition, while the combined inhibition of EDI3 and HER2 resulted in a dramatic loss in viability in the trastuzumab-resistant HCC1954 cells, this effect appears to be primarily due to the decrease in EDI3, further indicating that EDI3 may be a relevant target in ER-HER2 + tumours that are resistant to HER2-targeted therapy. This evidence concerns the gene ESR1 and neoplasm.