227Th-Trastuzumab corixetan

In this study, researchers want to learn about the safety of drug BAY2701439 and how well the drug works in patients with advanced cancer that has the protein HER2 (Human Epidermal growth factor Receptor 2) and cannot be cured by currently available treatment options. The study will include patients with HER2 expressing breast, gastric (stomach) or gastroesophageal (stomach and esophagus) cancer, as well as other cancers that have HER2. Researchers want to find the best dose of BAY2701439 for patients and look at the way the body absorbs, distributes and excretes the drug.
The study drug is a type of therapy called a 'targeted alpha therapy' which uses an antibody to deliver a radioactive particle to cancer cells. BAY2701439 contains thorium-227 which emits radiation (a lot of energy that moves from one place to another with damaging effects). The thorium-227 in the drug is attached to an 'antibody' (large protein) that specifically binds to HER2 on the cancer cells and will emit its radiation in the form of alpha particles. The alpha particles are expected to damage the tumor cells and cause them to die, but spare surrounding tissue as alpha particles travel only very short distances in the body. This is the first study in humans for drug BAY2701439. Patients participating in this study will receive the drug by injection every 6 weeks a maximum 6 times. Observation after treatment last up to 3 years.