A Study to Find a Suitable Dose of ASP4396 in Adults With Solid Tumors

Genes contain genetic code which tell the body which proteins to make. Some types of cancer are caused by changes, or mutations, in a gene called KRAS. Researchers are looking for ways to stop the actions of abnormal proteins made from the mutated KRAS gene. The so-called G12D mutation in the KRAS gene is common in people with some solid tumors. ASP4396 is being developed as a potential new treatment for solid tumors in people who have the G12D mutation in their KRAS gene. ASP4396 is not currently available as a treatment for the public. In this study, researchers will learn how ASP4396 is processed by and acts upon the body. This information will help find a suitable dose and to check for potential medical problems from ASP4396. In this study, ASP4396 is being given to humans for the first time. People in this study will be adults with locally advanced (unresectable), or metastatic solid tumors with the G12D mutation in their KRAS gene. Locally advanced means the cancer has spread to nearby tissue. Unresectable means the cancer cannot be removed by surgery. Metastatic means the cancer has spread to other parts of the body. They may have been previously treated with standard therapies or refused to receive those treatments. The main aims of the study are to check the safety of ASP4396, how well people cope with medical problems during the study (how well it is tolerated), and to find a suitable dose of ASP4396. This is an open-label study. This means that people in this study and clinic staff will know that they will receive ASP4396. This study will be in 2 parts. Part 1 is called Dose Escalation. Different small groups of people will receive lower to higher doses of ASP4396. For each dose, all medical problems will be recorded. The first group will receive the lowest dose of ASP4396. A medical expert panel will check the results and decide if the next group can receive a higher dose of ASP4396. The panel will do this until all groups have taken ASP4396 or un