The FDA granted accelerated approval to zanidatamab for previously treated, unresectable or metastatic HER2-positive biliary tract cancer, based on a 52% overall response rate in the HERIZON-BTC-01 trial. Common adverse effects included diarrhea, infusion-related reaction, abdominal pain, and fatigue. The ongoing HERIZON-BTC-302 trial will confirm efficacy in the frontline setting.