Safety Study of VAL-083 in Patients With Recurrent Malignant Glioma

Inclusion Criteria: * Patients must be greater than or equal to 18 years old. * Histologically confirmed initial diagnosis of primary WHO Grade IV malignant glioma (glioblastoma), now recurrent; or Cohorts 2 and 3 only: progressive secondary brain tumor, has failed standard brain radiotherapy, and has brain tumor progression after at least one line of systemic therapy. Patients with progressive secondary brain tumors will not be enrolled under this protocol following the completion of Cohort 3. * If GBM, previously treated for GBM with surgery and/or radiation, if appropriate, and must have failed both bevacizumab (Avastin) and temozolomide (Temodar), unless either or both are contraindicated. * If GBM, greater than or equal to 12 weeks from radiotherapy, or 4 weeks if a new lesion, relative to the pre-radiation MRI, develops that is outside the primary radiation field. * Cohorts 2 \& 3 only: Patients with secondary brain tumors must be greater than or equal to 4 weeks from radiotherapy. Patients with progressive secondary brain tumors will not be enrolled under this protocol following the completion of Cohort 3. * At least 4 weeks from last chemotherapy or bevacizumab (Avastin) therapy (6 weeks for nitrosourea or mitomycin C), or for chemotherapy regimes given continuously or on a weekly basis with limited potential for delayed toxicity, at least 2 weeks from last dose. * At least 21 days or 5 half-lives (whichever is shorter) since prior investigational anti-cancer drugs. A minimum of 10 days between termination of the investigational drug and administration of DAG is required * Recovered from all treatment-related toxicities to Grade 1 or less. * Must have a Karnofsky performance status of \> 50 with a predicted life expectancy of at least 12 weeks. * Must have known MGMT methylation and IDH1 mutation status to be screened for study entry. Exclusion Criteria: * Current history of neoplasm other than the entry diagnosis. Patients with previous cancers treated and cured with local therapy alone may be considered with approval of the Medical Monitor. * Evidence of leptomeningeal spread of disease. * Evidence of recent hemorrhage on baseline MRI of the brain. * Concurrent severe, intercurrent illness. * History of severe cardiac disease. * Significant vascular disease. * History of stroke or transient ischemic attack within 6 months prior to beginning treatment. * Concomitant medications that are known inducers of CYP. * Concomitant medications that are strong inhibitors of cytochrome P450 and CYP3A up to 14 days before Cycle 1 Day 1 (pimozide, diltiazem, erythromycin, clarithromycin, and quinidine, and amiodarone up to 90 days before) * Known to be HIV positive or to have an AIDS-related illness. * Pregnant or breast feeding.