A Study to Find a Suitable Dose of ASP5834 in Adults With Solid Tumors

Genes contain genetic code which tell the body which proteins to make. Many 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. ASP5834 is being studied in people with solid tumors who have certain KRAS gene mutations. Some people with solid tumors of the colon or rectum (colorectal cancer), will be given ASP5834 with panitumumab. Panitumumab is a treatment for colorectal cancer. In this study, the researchers will learn how ASP5834 is processed by and acts upon the body. This information will help find a suitable dose of ASP5834 and check for any potential medical problems from the treatment. The main aims of this study are to check the safety of ASP5834 given by itself or given with panitumumab, and how well it is tolerated; and to find a suitable dose of ASP5834 given by itself or given with panitumumab. People in this study will be adults with locally advanced, unresectable, or metastatic solid tumors with certain KRAS gene mutations. 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 either haven't responded to standard treatment or couldn't be given standard treatment. The key reasons people cannot take part are if they have specific uncontrollable cancers such as symptomatic or untreated cancers in nervous system, have specific heart conditions, swelling and irritation of lung tissues (pneumonitis or interstitial lung disease, also called ILD), infections, or have recently had a stroke or a bleed on the brain. In this study, ASP5834 is being given to humans for the first time. This is an open-label study. This means that people in this study and clinic staff will know that they will receive ASP5834 by itself or ASP5834 with panitumumab. 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 either: ASP5834 by itself or ASP5834 with panitumumab. Only people who have colorectal cancer will receive ASP5834 with panitumumab. People with any type of solid tumor will receive ASP5834 by itself. For each dose, all medical problems will be recorded. A medical expert panel will check the results and decide if the next group can receive a higher dose of ASP5834. The panel will do this until the planned maximum number of people are treated or until suitable doses have been selected for Part 2. Part 2 is called Dose Expansion. Other different small groups of people will receive ASP5834 or ASP5834 with panitumumab. They will receive the most suitable doses worked out from Part 1. In both parts of the study, the study treatments ASP5834 and panitumumab will be given through a vein. This is called an infusion. Each study treatment cycle is either 21 days or 28 days long. People will continue study treatment until: they have medical problems from the study treatment they can't tolerate; their cancer gets worse; they start other cancer treatment; or they ask to stop study treatment. People will visit the clinic on certain days during their study treatment, with extra visits during the first 2 cycles of study treatment. The study doctors will check for any medical problems from ASP5834. Also, people in the study will have a health check. On some visits they will also have scans to check for any changes in their cancer. Tumor samples will be taken at certain visits during study treatment with the option of a tumor sample being taken if people's cancer gets worse or the cancer comes back. People will visit the clinic shortly after stopping treatment for a health check. After this, people will have health checks every couple of months to check the condition of their cancer. The number of visits and checks done will depend on the health of each person and whether they completed their study treatment or not. It is expected that people will be in this study for about 1 year.