If you join this study, you will be placed into one of two groups by chance, like flipping a coin. One group will take a medicine called velzatinib, and the other group will take a medicine called imatinib. You will take the medicine by mouth every day.

The study has three parts called screening, treatment, and follow up. During screening, doctors will do tests to make sure the study is right for you. During treatment, you will visit the clinic about once every four weeks for checkups, blood tests, and scans.

You may stay in the study for a long time if the medicine is helping and is safe, with participation lasting up to about six years. After you stop taking the medicine, the study team will continue to check on your health through visits or phone calls.

This study is looking at advanced gastrointestinal stromal tumors (GIST) that have spread to other parts of the body or cannot be removed by surgery.

People may be able to join this study if they are 18 years old or older and have a type of cancer called gastrointestinal stromal tumor that has spread or cannot be removed with surgery. Their cancer must have certain genetic changes, called KIT or PDGFRA mutations. They must not have received treatment for this type of cancer before. They also cannot have had a bone marrow transplant or an organ transplant in the past.

This study is testing a new medicine called velzatinib and comparing it to a standard treatment called imatinib. Researchers want to learn if the new medicine can work better to slow down or stop cancer growth. They will also study how safe the medicine is and what side effects it may cause.