Patients with metastatic GC have poor survival outcomes, with the median overall survival of ≈1 year.[2] Although the anti‐HER2 agent trastuzumab has shown promising therapeutic effects in certain patients, the results of clinical trials testing drugs targeting EGFR, mTOR, or VEGF‐A have been unsatisfactory.[3, 4, 5, 6]. Here, ERBB2 is linked to gastric cancer.