Study of DCC-2618 in Patients With GIST After at Least 3 Prior Treatments

Inclusion Criteria: 1. Participants with a histologically confirmed diagnosis of GIST. 2. Participants who are refractory or intolerant to treatment with at least imatinib, sunitinib, and regorafenib. 3. Participants with at least one measurable lesion per the modified Response Evaluation Criteria in Solid Tumors (mRECIST) within 28 days prior to the first administration of the investigational product. 4. Participants with an Eastern Cooperative Oncology Group (ECOG) Performance Status of 0-1. Exclusion Criteria: 1. Participants with a concomitant or prior history of severe hypersensitivity reactions to other tyrosine kinase inhibitors. 2. Participants with uncontrolled diabetes mellitus. 3. Participants with a systemic infection requiring treatment.