Additional Study Information: The purpose of this study is to evaluate how safe the investigational drug, DSP-0390, is at different doses and to identify a recommended dose that is safe for further study. Investigational means that the study drug is currently being tested and has not been approved for use alone or in combination with any drug by the U.S. Food and Drug Administration (FDA) or any other health or regulatory authority in other countries. DSP-0390 is an oral drug that is being tested in people with high-grade glioma. This drug may help to inhibit or block emopamil binding protein (EBP), a protein that is needed for the formation of cholesterol by cancer cells which they need to grow and divide (this is not inhibiting absorption of cholesterol one gets from their diet). This study will have two parts: dose escalation and dose expansion. The purpose of dose escalation is to test the safety of DSP-0390 at different dose levels and to find out what the highest dose of the study that should be used in dose expansion. The purpose of dose expansion is to gather more information about DSP-0390 and its effects for other studies which may be completed in the future.