The general mechanisms of trastuzumab resistance that have been intensively studied include the following: (a) The difficulty associated with trastuzumab binding to HER2 is caused by a structural mutation in HER2, which generates a truncated p95HER2 isoform [9, 10]; (b) the upregulation of HER2 downstream signaling pathways; (c) signaling through alternate pathways; and (d) failure to stimulate immune‐mediated mechanisms to eradicate tumor cells [10]. This evidence concerns the gene ERBB2 and neoplasm.