A Drug-Drug Interaction Study to Evaluate the Effect of Ripretinib on the Pharmacokinetics of a CYP2C8 Probe Substrate in Patients with Advanced GIST

Inclusion Criteria: 1. Patients ≥18 years of age. 2. Patients must have a histologic diagnosis of GIST. 3. Patients must have GIST that has progressed on or have intolerance to at least 2 lines of prior TKI therapies. 4. Patients must have an Eastern Cooperative Oncology Group performance score of ≤ 2. 5. If a female of childbearing potential, must have a negative pregnancy test prior to enrollment and agree to follow the contraception requirements. 6. Adequate organ and bone marrow function. Exclusion Criteria: 1. Received prior anticancer or other investigational therapy within 28 days or 5× the half-life prior to the first dose. 2. Prior treatment with ripretinib. 3. Patients who have had prior repaglinide treatment within 14 days prior to Cycle 1 Day 1. 4. History or presence of clinically relevant cardiovascular abnormalities. 5. Gastrointestinal abnormalities including but not limited to: * inability to take oral medication, * malabsorption syndromes, * requirement for intravenous alimentation. 6. Patients who have type 1 or type 2 diabetes.