A plain language summary of the results from the phase 2b HERIZON-BTC-01 study of zanidatamab in participants with HER2-amplified biliary tract cancer

Researchers wanted to study whether the research drug zanidatamab could help people with a type of cancer called biliary tract cancer. In some people, biliary tract cancer cells make extra copies of a gene called HER2 (also called ERBB2). This is known as being HER2-amplified. Zanidatamab is an antibody designed to destroy cancer cells that have higher-than-normal HER2 protein or gene levels. Zanidatamab is currently under research and is not yet approved for any diseases. Participants in this phase 2b clinical study had tumors that were HER2-amplified and at the advanced or metastatic stage. Participants also had cancer which had become worse after previous chemotherapy or had side effects that were too bad to continue chemotherapy. They also had to meet other requirements to be enrolled. Researchers measured the amount of HER2 protein in the tumor samples of the participants who were enrolled. There were 80 participants with tumors that were both HER2 amplified and had higher-than-normal HER2 protein amounts (considered to be 'HER2-positive'). There were 7 participants with tumors that were HER2-amplified, but had little-to-no levels of the HER2 protein (considered to be 'HER2-low'). All participants in the study were treated with zanidatamab and no other cancer treatments once every 2 weeks.