ERBB2 and biliary tract cancer: In the same study, eight patients with biliary tract cancer overexpressing HER2 and three patients with ERBB2 structural abnormalities (D277Y, S310F, and A775-G776ins YVMA) were treated with pertuzumab plus trastuzumab, and the response rates were 37.5 and 33.3%, respectively [75,76].