Inclusion Criteria:

   - Histologically confirmed primary central nervous system (CNS) high-grade glioma,
   including any of the following:

      - Glioblastoma multiforme

      - Anaplastic astrocytoma

      - Anaplastic oligodendroglioma

      - High-grade astrocytoma not otherwise specified (i.e., anaplastic ganglioglioma,
      anaplastic mixed glioma, or anaplastic mixed glioneuronal tumors)

         - No diffuse pontine gliomas, gliomatosis cerebri, and primary spinal cord
         high-grade astrocytoma

      - Gliosarcoma

   - Recurrent or progressive disease that is refractory to standard therapy

   - Radiographically documented measurable disease

      - Lesion must be at least twice the thickness of the image from which it is derived
      (e.g., 10 mm for a 5 mm slice thickness)

   - No diffuse pontine gliomas

   - No evidence of prior CNS bleeding

   - Karnofsky performance status (PS) 50-100% (patients > 16 years of age)

   - Lansky PS 50-100% (patients =< 16 years of age)

   - Life expectancy >= 8 weeks

   - Absolute neutrophil count (ANC) >= 1,000/μL

   - Platelet count >= 100,000/μL (transfusion independent)

   - Hemoglobin >= 8.0 g/dL (red blood cell [RBC] transfusions allowed)

   - Creatinine clearance or radioisotope glomerular filtration rate >= 70mL/min OR serum
   creatinine based on age/gender as follows:

      - 0.4 mg/dL (1 month to < 6 months of age)

      - 0.5 mg/dL (6 months to < 1 year of age)

      - 0.6 mg/dL (1 to < 2 years of age)

      - 0.8 mg/dL (2 to < 6 years of age)

      - 1.0 mg/dL (6 to < 10 years of age)

      - 1.2 mg/dL (10 to < 13 years of age)

      - 1.5 mg/dL (male) or 1.4mg/dL (female) (13 to < 16 years of age)

      - 1.7 mg/dL (male) or 1.4mg/dL (female) (>= 16 years of age)

   - Total bilirubin =< 1.5 times upper limit of normal (ULN) for age

   - Alanine aminotransferase (ALT) and aspartate aminotransferase (AST) =< 2.5 times ULN
   for age

   - No evidence of dyspnea at rest

   - No exercise intolerance

   - Pulse oximetry > 94%, if determination is clinically indicated

   - Seizure disorder is allowed provided it is well-controlled with anticonvulsants

   - No uncontrolled infection

   - Not pregnant or nursing

   - Negative pregnancy test

   - Fertile patients must use effective contraception

   - Recovered from all prior therapy

   - No more than two prior treatments for high-grade glioma (i.e., one initial treatment
   and one treatment for relapse)

   - More than 2 weeks since prior myelosuppressive chemotherapy (>= 6 weeks for
   nitrosoureas)

   - At least 1 week since prior non-myelosuppressive chemotherapy, immunotherapy, or
   biologic therapy

   - At least 2 weeks since prior local palliative radiotherapy (i.e., small port) to a
   symptomatic non-target lesion only

   - At least 3 months since prior craniospinal radiotherapy

   - At least 6 weeks since prior substantial bone marrow radiotherapy

   - At least 6 months since prior allogeneic stem cell transplant (SCT) or rescue

      - Patients who have undergone prior allogeneic SCT and who have graft-versus-host
      disease (GVHD) must have controlled GVHD that is =< grade 2

   - At least 1 month since prior autologous SCT

   - More than 1 week since prior growth factors (> 3 weeks for pegfilgrastim [Neulasta®])

   - No other concurrent anticancer therapy, including chemotherapy or immunomodulating
   agents

   - No other concurrent experimental agents or therapies

   - No concurrent alternative or complimentary therapies

   - No concurrent homeopathic medicines

   - No concurrent nonsteroidal anti-inflammatory drugs (NSAIDs) or acetylsalicylic acid
   (aspirin)

   - No concurrent steroids as anti-emetics

   - Concurrent steroids for treatment of increased intracranial pressure allowed if on a
   stable or decreasing dose for >= 1 week before study entry

   - Concurrent radiotherapy to localized painful lesions allowed provided >= 1 measurable
   lesion is not irradiated