Investigation of Oral OKN-007 in Recurrent High-grade Glioma Participants

Inclusion Criteria: * Confirmed histopathology of recurrent gliomas that were originally diagnosed as, Glioblastoma (WHO Grade IV), Astrocytoma (WHO Grade III), or Oligodendroglioma (WHO Grade III). Participants with an initial diagnosis of a lower-grade glioma are eligible if a subsequent biopsy was determined to be glioblastoma. * Unequivocal radiographic evidence of tumor progression by MRI as per the RANO criteria within 14 days prior to registration. * At least one measureable lesion per RANO. * Prior radiotherapy * Prior Temozolomide treatment, unless contraindications or intolerance. * Last cytotoxic chemotherapy or biologic therapy treatment 14 or more days before study start (greater than or equal to 42 days if nitrosourea was administered). * ECOG performance status of 0, 1 or 2. * Full recovery (≤ grade 1) from the toxic effects of any earlier intervention and a minimum of 28 days from the last administration of any investigational agent. * Adequate renal, liver and bone marrow function: Leukocytes \>3,000/mcL; Absolute neutrophil count \>1,500/mcL; Platelets \>100,000/mcL; Total bilirubin ≤ 1.5 x ULN; AST (SGOT) / ALT (SGPT) ≤ 2.5 x ULN; Creatinine clearance ≥ 60 mL/min calculated as per Cockcroft-Gault equation. * Must be ≥ 18 years of age. * Life expectancy (as assessed by the Investigator) at least three months. * Capability of swallowing oral medication (4-6 size 0 capsules twice or thrice a day). * Have provided verbal and written informed consent. * Must be willing to have multiple blood draws for PK analysis. * Female participants, of childbearing potential, must have a negative serum pregnancy test within 72 hours of taking study medication and agrees to abstain from activities that could result in pregnancy from enrollment through 120 days after the last dose of study treatment. * Male participants must agree to use an adequate method of contraception. Exclusion Criteria: * Second primary malignancy expected to require treatment within a 6 month period (except adequately treated basal cell carcinoma of the skin). Participants who had another malignancy in the past, but have been free of active disease for more than 2 years, are eligible. * Have received treatment within the last 28 days with a drug that has not received regulatory approval for any indication at the time of study entry. * Serious concomitant systemic disorders (for example, active infection or abnormal electrocardiogram (ECG) indicative of cardiac disease) that, in the opinion of the Investigator, would compromise the safety of the participants and his/her ability to complete the study. * with abnormal sodium, potassium, or creatinine levels ≥ grade 2. * with PT/PTT or INR above the upper limit of normal, unless treated with anticoagulants (e.g. warfarin). In such cases coagulation parameters (INR) should be monitored weekly for the first six weeks of the study. * Inability to comply with protocol or study procedures. * Women who are pregnant or breastfeeding. * For participation in a food effect cohort, uncontrolled Diabetes Type I or uncontrolled Type II (HbA1c \> 7 mmol/L assessed locally) as judged by the Investigator.