Dexanabinol in Patients With Brain Cancer

The purpose of this study is to try to determine the maximum safe dose of dexanabinol that can be administered to people with brain cancer. Other purposes of this study are to: * find out what effects (good and bad) dexanabinol has; * see how much drug gets into the body by collecting blood and cerebrospinal fluid for use in pharmacokinetic (PK) studies; * learn more about how dexanabinol might affect the growth of cancer cells; * look at biomarkers (biochemical features that can be used to measure the progress of disease or the effects of a drug).