This is a non-comparative, single arm, biomarker-driven study with VAL-083. Forty-eight (48) eligible patients will receive VAL-083 at 40 mg/m2 IV on days 1, 2, and 3, for up to 12, 21-day treatment cycles or until they fulfill one of the criteria for study discontinuation (disease progression, death, intolerable toxicities, investigator's judgment, or withdrawal of consent). Disease status will be evaluated with clinical and MRI evaluation every other 21-day cycle, while the patient is receiving VAL-083 treatment, and then approximately every 42 ± 7 days while remaining on study. Symptom burden will be evaluated using the MD Anderson Symptom Inventory-Brain Tumor (MDASI-BT) completed by patients at baseline and at the time of each imaging evaluation.