Inclusion Criteria

DISEASE CHARACTERISTICS:

- Diagnosis of 1 of the following:

- Malignant glioma, including the following subtypes: glioblastoma or gliosarcoma,
anaplastic astrocytoma, anaplastic oligodendroglioma, anaplastic mixed glioma,
or malignant glioma not otherwise specified, meeting the following criteria:

- Not required to have measurable or evaluable disease

- Must have failed prior radiation therapy > 4 weeks ago

- Must have failed at least 1 prior chemotherapy regimen

- Confirmation of tumor progression by MR spectroscopy, PET scan, or
biopsy/resection if prior radiosurgery was performed

- Primary CNS lymphoma, meeting the following criteria:

- Measurable disease as defined by bidimensionally measurable lesions with
clearly defined margins by CT scan or MRI

- Must have failed at least one prior chemotherapy regimen

- Must have failed at least one agent or regimen

- Brain metastases from a solid tumor, meeting the following criteria:

- Measurable disease as defined by bidimensionally measurable lesions with
clearly defined margins by CT scan or MRI

- Biopsy is not required if radiographic imaging is consistent with brain
metastases

- Must have failed prior whole-brain radiotherapy

- Patients with leptomeningeal metastases with or without brain metastases
are eligible for therapy (may be diagnosed by MRI or cytology)

- Confirmation of tumor progression by MR spectroscopy, PET scan, or
biopsy/resection if prior radiosurgery was performed

- Effusions or fluid collections must be drained prior to study entry

PATIENT CHARACTERISTICS:

- Karnofsky performance score ≥ 60

- WBC > 3,000/mm^3

- Absolute neutrophil count > 1,500/mm^3

- Platelet count > 100,000/mm^3

- Hemoglobin > 10 mg/dL (transfusion allowed)

- SGOT/SGPT < 3.0 times upper limit of normal (ULN)

- Bilirubin < 1.5 times ULN

- Creatinine < 1.5 mg/dL

- Creatinine clearance > 45 mL/min

- Women of childbearing potential and sexually active males must commit to the use of
effective contraception while on study and for 3 months after completing study
treatment

- Women who are pregnant or breast-feeding are not eligible for study treatment

- Negative pregnancy test

- Able to take steroids, vitamin B12, or folate

- No significant medical illnesses or infection that, in the investigator's opinion,
cannot be adequately controlled with appropriate therapy or would compromise the
patient's ability to tolerate this therapy

- Only one active tumor type allowed, except nonmelanoma skin cancer or carcinoma in
situ of the cervix

- A history of other malignancies are acceptable if in complete remission and off
all therapy for that disease for a minimum of 3 years

PRIOR CONCURRENT THERAPY:

- See Disease Characteristics

- More than 4 weeks since prior whole-brain or other radiotherapy

- Recovered from any side effects (6 weeks for a nitrosourea; 4 weeks for temozolomide,
procarbazine, etoposide or experimental agent; 3 weeks for isotretinoin or tamoxifen)
(for patients with gliomas)

- No more than 2 prior chemotherapeutic agents or regimens (includes biologic agents)
(for patients with gliomas)

- Recovered from prior biopsy or re-resection of the tumor (10-14 days for resection or
3-5 days for a biopsy) (for patients with gliomas)

- May not be on any other chemotherapy except for hormonal therapy or trastuzumab
(Herceptin®) (for patients with brain metastases)

- No limitations on prior CNS-directed therapies (for patients with brain metastases)

- Able to discontinue nonsteroidal anti-inflammatory drugs (NSAIDs)

- Patients taking NSAIDs or aspirin are required to interrupt therapy for at least 2
days before the study treatment and 2 days after the infusion