According to the efficacy of CH12 and the inhibition effect against ERK, AKT and Jak1/STAT3 pathway in EGFRvIII+HER2+ breast cancers, we wondered whether the combination of trastuzumab with CH12 could reverse trastuzumab resistance in EGFRvIII+HER2+ breast cancer. This evidence concerns the gene ERBB2 and breast cancer.