Inclusion Criteria:

- Patient has had a prior, histologically-confirmed, diagnosis of a grade III or grade
IV glioma (including glioblastoma, anaplastic astrocytoma, gliosarcoma, anaplastic
oligodendroglioma, or anaplastic oligoastrocytoma), or has a prior,
histologically-confirmed, diagnosis of a grade II glioma and now has radiographic
findings consistent with a high-grade glioma (grade III or IV)

- Imaging studies show evidence of recurrent supratentorial tumor(s)

- The patient must be in need of a craniotomy for tumor resection or a stereotactic
brain biopsy for the purpose of diagnosis or differentiating between tumor
progression versus treatment-induced effects following radiation therapy +/-
chemotherapy

- Based on the neurosurgeon's judgment, there is no anticipated physical connection
between the post-resection tumor cavity and the cerebral ventricles

- Patient's high-grade glioma has recurred or progressed after chemoradiation

- Patient has a Karnofsky Performance Status of >= 70%

- Patient has a life expectancy of >=3 months

- If patient requires corticosteroids for the control of cerebral edema, s/he must be
on a stable dose for at least 1 week prior to enrollment

- Patient has recovered from toxicity of prior therapies; an interval of at least 12
weeks must have elapsed since the completion of radiation therapy; at least 6 weeks
since the completion of nitrosourea-containing chemotherapy regimen; and at least 4
weeks since the completion of a non-nitrosourea-containing cytotoxic chemotherapy
regimen; if a patient's most recent treatment was with a targeted agent only; and
s/he has recovered from any toxicity of this targeted agent, then a waiting period of
only 2 weeks is needed from the last dose and the start of study treatment, with the
exception of bevacizumab where a wash out period of at least 4 weeks is required
before starting study treatment

- Absolute neutrophil count of >= 1,500 cells/mm^3 and platelet count >= 100,000
cells/mm^3

- Total bilirubin =< 2.0 mg/dl

- Aspartate aminotransferase (AST) (serum glutamic oxaloacetic transaminase [SGOT]) =<
4 times the institutional upper limit of normal

- Serum creatinine =< the institutional upper limit of normal

- Patients must be able to swallow pills

- Patients must be able to understand and be willing to sign a written informed consent
document

- Female patients of child-bearing potential and sexually active male patients must
agree to use an effective method of contraception while participating in this study

- Women of childbearing potential must have a negative pregnancy =< 2 weeks prior to
registration

INCLUSION CRITERIA FOR PROCEEDING TO TREATMENT WITH 5-FC:

- Patients must be tolerating oral intake

- Patients' daily total dose of dexamethasone must be < 12 mg by Day 4

Exclusion Criteria:

- Patients who are currently receiving chemotherapy, radiotherapy, or are enrolled in
another treatment clinical trial

- Patients who have anti-human leukocyte antigen (HLA) antibodies specific for HLA
antigens expressed by the HB1.F3.CD NSCs

- Patients who are unable to undergo an MRI

- Patients with chronic or active viral infections of the central nervous system (CNS)

- Patients who are allergic to 5-FC or 5-FU

- Patients who have a serious medical or psychiatric illness that could, in the
investigator's opinion, potentially interfere with the completion of treatment
according to this protocol

- Female patients who are pregnant or breast-feeding

- Patients who have not recovered from the toxicities of prior chemotherapy or
radiotherapy

- Patients who require anti-seizure medication but are not on a stable dose of
anti-seizure medication for at least 1 week prior to enrollment