Methimazole in Patients With Progressive Glioblastoma

The purpose of this study is to test the effectiveness, safety, and tolerability of a drug called Methimazole. The investigational drug, Methimazole is not FDA approved for brain tumors, but it is used to treat thyroid illnesses. Different doses of Methimazole will be given to several study participants with glioblastoma. The first several study participants will receive the lowest dose. If the drug does not cause serious side effects, it will be given to other study participants at a higher dose. The doses will continue to increase for every group of study participants until the side effects occur that require the dose to be lowered. The procedures in this study are research blood draws, physical exams, collection of medical history, MRI scans, and study drug administration.