Additional Study Information: Deciphera Pharmaceuticals, LLC., the Sponsor of this study, is developing a drug called DCC-2618 to treat Gastrointestinal Stromal Tumors (GIST) that are growing because of changes in specific genes. Genes are the instructions that tell a part of your body called a cell what to do. Cancer changes the genes so that the instructions are no longer correct. DCC-2618 is designed to block signals from genes that cause cancer to grow. The study is being done to learn more about the safety of the study drug and how well it works against cancer in patients who have received prior anticancer treatments. We will also look at how DCC-2618 may affect your body.