A Study of ONC201 for Refractory Meningioma

The goal of this clinical trial is to learn about treatment for a type of brain tumor called a meningioma. This study will enroll two groups of people. One group will be for people who will receive surgery to remove their brain tumor. The other group will be for people who have previously received treatment for their brain tumor but do not have any other available options for treatment. The primary goals of this study are: 1. To measure how much of the study drug is present in tumor tissue taken from patients during surgery to remove their brain tumor 2. To measure the length of time between a study participant's first dose of study treatment until the time when their brain tumor gets worse or their death