Methotrexate Infusion Into the Fourth Ventricle in Children With Malignant Fourth Ventricular Brain Tumors: A Pilot Study

Inclusion Criteria:

1. There will be a two-step process of eligibility assessment: Step 1: Eligibility for catheter placement and possible surgical removal of tumor. Step 2: Eligibility for methotrexate infusion.
2. Step 1 Eligibility (Pre-Operative Eligibility) Includes: Diagnosis and Age - Patients with tumor originally located within the posterior fossa of the brain: \*Patients ≤ age 21 years with recurrent medulloblastoma (PNET) involving the brain and/or spine \*Patients ≤ age 21 years with recurrent ependymoma involving the brain and/or spine \*Patients ≤ age 21 years with recurrent atypical teratoid/rhabdoid tumor (AT/RT) involving the brain and/or spine.
3. Step 1 Elig.: Life Expectancy - Patients must have a life expectancy of at least 12 weeks as estimated by the treating oncologist and neurosurgeon to be considered for enrollment.
4. Step 1 Elig: Central Nervous System Function - Patients may be enrolled in the study if they have an altered neurological status, such as somnolence, which is attributed to hydrocephalus and/or mass effect from the brain tumor by the treating physicians. However, after tumor resection and placement of the catheter into the fourth ventricle, the protocol will only be continued if the patient has adequate central nervous system function, defined as: patient is not severely somnolent or comatose and has adequate clinical performance status as defined in protocol section 3.2.2.1.
5. Step 2 Elig. (MTX Infusion Elig.): Clinical Performance Status - Patients must have a Lansky score of 50 or greater if ≤ 16 years of age and a Karnofsky score of 50 or greater if they are \> 16 years of age to be eligible for enrollment (See Protocol Section 14.1 for Lansky Play-Performance Scale information; See Protocol Section 14.2 for Karnofsky Performance Scale information).
6. Step 2 Elig: Pregnancy - Female patients who are post-menarchal must have a negative pregnancy test to be eligible. Pregnant or lactating female patients are ineligible.
7. Step 2 Elig: Patients must have fully recovered from the acute toxic effects of all prior chemotherapy, immunotherapy, or radiotherapy prior to entering this study. a. Myelosuppressive chemotherapy: Must not have received within 2 weeks of entry onto this study. b. Hematopoietic Growth Factors: At least 7 days since the completion of therapy with a growth factor. c. Biologic (anti-neoplastic agent): At least 7 days since the completion of therapy with a biologic agent. 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. These patients must be discussed with the study chair on a case by case basis.
8. Step 2 Elig: Bone Marrow Function - patients must have adequate bone marrow function, defined as: a. Peripheral absolute neutrophil count (ANC) ≥ 1000/µL b. Platelet count ≥ 30,000/µL (transfusion independent) c. Hemoglobin ≥ 9.0 gm/dL (may receive RBC transfusions) d. Post-op CSF flow study shows re-establishment of CSF flow.
9. All patients and/or their parents or legal guardians must sign a written informed consent.

Exclusion Criteria:

1. Patients will be excluded from this study if currently enrolled in another experimental treatment protocol.
2. Patients will be excluded from this study if they have any evidence of infection, in any site, at the time of considered enrollment.