ERBB2 and cancer: For instance, trastuzumab, a conjugate of HER‐2 monoclonal antibody with topoisomerase I inhibitor, has been applied as a first‐line treatment for HER‐2 positive cancer patients35, 36; however, according to reports, the response rate of trastuzumab ranges was only from 30% to 60% in gastroesophageal cancer.37, 38