Inclusion Criteria:

   - Diagnosis: Patients must have a histologically confirmed diagnosis of supratentorial
   high-grade glioma or supratentorial ependymoma that is recurrent, progressive or
   refractory.

   - Patients must have failed standard therapy and at the time of study entry have
   recurrent, progressive or refractory disease with no known curative options.

   - Disease Status: Patients must have bi-dimensionally measureable disease, defined as at
   least one lesion that can be accurately measured in at least two planes

      - This disease must be located primarily in the supratentorial region

      - Patients with significant disease that is metastatic outside of the
      supratentorial region are ineligible

   - Age: Patients must be ≥ 5 but ≤ 21 years of age at the time of enrollment.

   - Prior Therapy: Patients must have recovered from the acute treatment related
   toxicities (defined as ≤ grade 1) of all prior chemotherapy, immunotherapy, or
   radiotherapy prior to entering this study.

   - Myelosuppressive Chemotherapy: Patients must have received last dose of known
   myelosuppressive chemotherapy >21 days prior to enrollment; >42 days if nitrosurea.

   - Biologic Agent: Biologic agent must have recovered from any acute toxicity potentially
   related to the agent and received their last dose of the biologic agent > 7 days prior
   to study enrollment.

   - For agents that have known adverse events occurring beyond 7 days after
   administration, this period must be extended beyond the time during which adverse
   events are known to occur.

   - Immunomodulatory treatment: Patient must have received the last dose >21 days prior to
   enrollment.

   - Monoclonal antibody treatment and agents with known prolonged half-lives: At least
   three half-lives must have elapsed prior to enrollment.

   - Radiation: Patients must have had their last fraction of:

      - Craniospinal irradiation (>24Gy) > 3 months prior to enrollment

      - Focal irradiation > 42 days prior to enrollment

      - Local palliative irradiation (small port) > 14 days

   - Surgery: Optune device application start date must be at least 4 weeks (28 days) from
   CNS surgical procedure. Excluding VP shunts, Endoscopic Third Ventriculostomy (ETV)
   for which treatment could start 10 days post procedure. Non-CNS surgical procedures
   such as but not limited to central venous catheter insertion at the discretion of
   treating physician and study chair.

   - Inclusion of Women and Minorities: Both males and females of all races and ethnic
   groups are eligible for this study.

   - Neurologic Status: Patients with neurological deficits should be stable for a minimum
   of 1 week prior to enrollment.

   - Performance Status: Karnofsky Performance Scale (KPS for > 16 years of age) or Lansky
   Performance Score (LPS for ≤ 16 years of age) assessed within two weeks of enrollment
   must be ≥ 60. Patients who are unable to walk because of neurologic deficits, but who
   are up in a wheelchair, will be considered ambulatory for the purpose of assessing the
   performance score.

   - Organ Function: Patients must have organ and marrow function as defined below:

Absolute neutrophil count ≥ 1.0 X 109/L; Platelets ≥ 100 X 109/L (transfusion independent);
Hemoglobin ≥8g/dl (may receive transfusions); Total bilirubin ≤1.5 times institutional
upper limit of normal (ULN); ALT(SGPT) ≤3 times institutional upper limit of normal;
AST(SGOT) ≤3 times institutional upper limit of normal; Albumin ≥2 g/dl. Serum creatinine
based on age/gender as noted below. Patients that do not meet the criteria below but have a
24 hour Creatinine Clearance or GFR (radioisotope or iothalamate) ≥ 70 ml/min/1.73 m2 are
eligible.

Age Maximum Serum Creatinine (mg/dL)

3 to < 6 years 0.8 (Male) 0.8 (Female); 6 to < 10 years 1 (Male) 1 (Female); 10 to < 13
years 1.2 (Male) 1.2 (Female); 13 to < 16 years 1.5 (Male) 1.4 (Female);

≥ 16 years 1.7 (Male) 1.4 (Female).

   - Head circumference: Patients must have minimum head circumference of 44 cm.

   - Compliance in Optune Device Usage: Patients must be willing to use the Optune device
   ≥18 hours/day for at least 23 days in a 28-day cycle, and keep head shaved throughout
   treatment.

   - Pregnancy Status: Female patients of childbearing potential must have a negative serum
   or urine pregnancy test.

   - Pregnancy Prevention: Patients of childbearing or child fathering potential must be
   willing to use a medically acceptable form of birth control, which includes
   abstinence, while being treated on this study.

   - Informed Consent: The patient or parent/guardian is able to understand the consent and
   is willing to sign a written informed consent document according to institutional
   guidelines.

   - Steroids: If patient is on corticosteroids, the dose must be stable or decreasing for
   at least 5 days prior to enrollment.

Exclusion Criteria:

   - Systemic Illness: Patients with any clinically significant unrelated systemic illness
   (serious infections or significant cardiac, pulmonary, hepatic or other organ
   dysfunction), that in the opinion of the investigator would compromise the patient's
   ability to tolerate protocol therapy, put them at additional risk for toxicity or
   would interfere with the study procedures or results.

   - Other Malignancy: Patients with a history of any other malignancy.

   - Concurrent Therapy: Patients who are receiving any other anticancer or investigational
   drug therapy are not eligible.

   - Inability to Participate: Patients who in the opinion of the investigator are
   unwilling or unable to return for required follow-up visits or obtain follow-up
   studies required to assess toxicity to therapy or to adhere to device usage plan,
   other study procedures, and study restrictions.

   - Tumor Location: Patients with primarily infra-tentorial or spinal cord tumor are not
   eligible.

   - Tumor Dissemination: Patients for who clinical suspicion is present of metastatic
   disease in the CSF or Spine must have MRI of Spine and CSF obtained (Lumbar puncture
   or through ommaya, EVD or Shunt) with negative cytology. Patients with CSF that is
   positive for tumor cells or metastatic disease found on MRI are ineligible.

   - Skull Defects: Patients with major skull defects (such as missing bone without
   replacement) are not eligible.

   - Neurological Disorder: Patients with active implanted electronic devices in the brain
   or spinal cord such as programmable VP shunts, deep brain stimulators, vagus nerve
   stimulators, are not allowed.

   - Cardiac Disorder: Patients with pacemaker, defibrillator, or documented significant
   arrhythmia, are not allowed.

   - Intracranial Objects: Patients with foreign body intracranially, such as bullet
   fragments, are not allowed, with the exception of VP-shunts (non-programmable) and
   Ommaya catheters.

   - Allergy: Patients with history of hypersensitivity to conductive hydrogel are not
   eligible.