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