['anaplastic astrocytoma', 'anaplastic oligodendroglioma', 'anaplastic oligoastrocytoma', 'glioblastoma', 'gliosarcoma']
['temozolomide']

        Inclusion Criteria:

          -  Patients must have pathologically proven diagnosis of high grade glioma

          -  Patients must have received prior radiation therapy and standard temozolomide

          -  Patients must be three or more months from the end of chemoradiotherapy or have biopsy
             or imaging consistent with disease progression

          -  Patients must have recovered from toxicity of prior therapy

          -  Eastern Cooperative Oncology Group (ECOG) performance status of 0-2 or better

          -  Absolute neutrophil count (ANC) count >= 1,500/mm^3

          -  Hemoglobin >= 8 g/dL

          -  Platelet count >= 100,000/mm^3

          -  Serum creatinine that is at or below 2.0 mg/dL

          -  Serum aspartate aminotransferase (AST) and alanine aminotransferase (ALT) less than
             1.5 times the upper limits of normal; note: if hepatic function is abnormal, the
             decision to initiate temozolomide treatment should carefully consider the benefits and
             risks for the individual patient

          -  Serum alkaline phosphatase less than 2.5 times the upper limits of normal; note: if
             hepatic function is abnormal, the decision to initiate temozolomide treatment should
             carefully consider the benefits and risks for the individual patient

          -  The patient must be aware of the neoplastic nature of his/her disease and willingly
             provide written, informed consent after being informed of the procedure to be
             followed, the experimental nature of the therapy, alternatives, potential benefits,
             side-effects, risks, and discomforts

          -  Women of reproductive potential must be non-pregnant and non-nursing and must agree to
             employ an effective barrier method of birth control throughout the study and for up to
             6 months following treatment

          -  Women of child-bearing potential must have a negative pregnancy test within 7 days of
             initiating study; (no childbearing potential is defined as age 55 years or older and
             no menses for two years or any age with surgical removal of the uterus and/or both
             ovaries)

        Exclusion Criteria:

          -  History of uncontrollable allergic reactions to temozolomide or ascorbic acid or to
             antiemetics appropriate for administration in conjunction with protocol-directed
             chemotherapy

          -  Known human immunodeficiency virus (HIV)-positivity AND actively being treated with
             highly active anti-retroviral therapy (HAART)

          -  History of glucose-6-phosphate dehydrogenase deficiency

          -  History of oxalate nephrolithiasis or urine oxalate > 60 mg/dL

          -  Anuria, dehydration, severe pulmonary congestion or pulmonary edema or fixed low
             cardiac input since all are conditions for which osmotic diuresis are contraindicated
             and ascorbic acid has high osmolarity

          -  Any other clinically significant medical disease or condition laboratory abnormality
             or psychiatric illness that, in the Investigator's opinion, may interfere with
             protocol adherence or a subject's ability to give informed consent

          -  Patients who are on the following drugs and cannot have a drug substitution:
             flecainide, methadone, amphetamines, quinidine, and chlorpropamide; note: high dose
             ascorbic acid may affect urine acidification and, as a result, may affect clearance
             rates of these drugs

          -  Simultaneous participation in other therapeutic clinical trials will not be allowed

          -  Inability to co-operate with the requirements of the protocol

          -  Pregnant and nursing women are excluded from this study
      