While GSDMB over-expression in breast and likely gastric [44] cancer is mostly due to GSDMB-HER2 gene co-amplification, our results together with our published data [12], prove that GSDMB transcription and translation are further upregulated specifically in response (early response and during acquired resistance) to different anti-HER2 drugs (trastuzumab, lapatinib) in HER2 breast cancer (cell lines and PDXs) and gastroesophageal tumor cells. This evidence concerns the gene GSDMB and breast cancer.