Study of Olaparib and Durvalumab in IDH-Mutated Solid Tumors

This is a phase 2 study of the combination of drugs olaparib and durvalumab for the treatment of isocitrate dehydrogenase or (IDH) mutated solid tumors. The purpose of this study is to assess the efficacy of the drug combination via overall response rate and overall disease control rate. It is believed that giving olaparib and durvalumab together would be more useful when given to patients with IDH-mutated solid tumors than giving each drug alone.

Patients with documented IDH mutations will be screened for eligibility within 4 weeks of the start of study treatment including medical history, physical exam, height, weight, vital signs, performance status, routine blood lab tests, pregnancy test, ECG, and tumor measurements for safety, and research blood and archival tumor tissue collection for biomarker research. In the event participants require surgery or biopsy during their participation in the study, samples of the tumor tissue removed will be collected for biomarker research. Eligible participants will be assigned to a cohort depending on their type of cancer: * Cohort A: IDH-mutated glioma (a type of brain/spinal cord cancer) * Cohort B: IDH-mutated cholangiocarcinoma (a type of bile duct cancer) While on the study drugs, participants will have many of the screening tests and procedures repeated for safety and for biomarker research. If participants are permanently taken of the study drugs for any reason, they will be asked to return to the clinic about 4 weeks after the last dose of study drugs to have tests and procedures done during the study repeated for safety and research purposes. After the End of Study Drug visit, participants will continue to be followed-up by telephone or by clinic visit every 8-12 weeks until they no longer wish to be followed or start a new anti-cancer treatment, or until 1 year after last dose of study drugs.