This study involves patients with Gastroesophageal Adenocarcinoma, which is a type of cancer that develops in the area where the esophagus (the tube connecting the throat to the stomach) meets the stomach. Specifically, this study focuses on a form of this cancer that has spread to other parts of the body, is positive for a protein called HER2, and is also positive for a marker called PD-L1. The treatment being studied includes a combination of several medications: JZP598 (also known as zanidatamab), pembrolizumab, and chemotherapy drugs including oxaliplatin, fluorouracil, and folic acid. All of these medications are given through infusion directly into a vein.
The purpose of this study is to evaluate how well the combination of zanidatamab with pembrolizumab and chemotherapy works in treating patients who have not previously received treatment for their advanced cancer. The study will look at whether this treatment combination can help control the disease and how long patients remain without their cancer getting worse.
During the study, patients will receive the study medications according to a specific treatment schedule that may continue for up to 104 weeks. Throughout this time, doctors will regularly monitor the patients through various examinations and tests to assess how the cancer responds to treatment and to watch for any side effects. The study will measure several outcomes including how many patients respond to the treatment, how long the treatment keeps the cancer under control, and the overall survival of patients. Safety will be carefully monitored by tracking any unwanted effects that occur during treatment, and quality of life will be assessed using questionnaires.



Germany