In light of trastuzumab capability to impair cancer stem cell subpopulation in HER2-positive GC30 and our reported data in HER2-positive BC models19,22, we speculate that d16HER2 variant can have a key role also in HER2-positive GC stemness, though we are aware that functional experiments are mandatory to validate our hypothesis. This evidence concerns the gene ERBB2 and breast cancer.