VNP40101M in Treating Young Patients With Recurrent, Progressive, or Refractory Primary Brain Tumors

DISEASE CHARACTERISTICS: * Histologically confirmed\* primary brain tumor, including benign brain tumors (e.g., low-grade glioma) * Recurrent or progressive disease OR refractory to standard therapy NOTE: \*Patients with intrinsic brain stem or diffuse optic pathway tumors do not require histological confirmation, but must have clinical and/or radiographic evidence of disease progression * No bone marrow disease PATIENT CHARACTERISTICS: Age * 21 and under Performance status * Karnofsky 50-100% (for patients \> 16 years of age) OR * Lansky 50-100% (for patients ≤ 16 years of age) Life expectancy * Not specified Hematopoietic * Absolute neutrophil count ≥ 1,000/mm\^3\* * Platelet count ≥ 100,000/mm\^3\* * Hemoglobin ≥ 8 g/dL\* NOTE: \*Unsupported Hepatic * Bilirubin ≤ 1.5 times upper limit of normal (ULN) * ALT and AST ≤ 2.5 times ULN * No overt hepatic disease Renal * BUN \< 25 mg/dL * Creatinine ≤ 1.5 times ULN for age OR * Glomerular filtration rate \> 70 mL/min * No overt renal disease Cardiovascular * Shortening fraction ≥ 30% by echocardiogram OR * Ejection fraction ≥ 50% by gated radionucleotide study * No clinically significant cardiac arrhythmia by EKG * No overt cardiac disease Pulmonary * DLCO ≥ 60% of predicted * Chest X-ray normal (defined as absence of pulmonary infiltrates, pneumonitis, pleural effusion, pulmonary hemorrhage, or fibrosis) AND a resting pulse oximetry reading of \> 94% in room air (for patients who cannot perform the DLCO) * No overt pulmonary disease Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Neurologic deficits allowed provided there has been no deficit progression for ≥ 1 week before study entry * No uncontrolled infection * No known hypersensitivity to polyethylene glycol PRIOR CONCURRENT THERAPY: Biologic therapy * At least 6 months since prior allogeneic bone marrow or stem cell transplantation * At least 3 months since prior autologous bone marrow or stem cell transplantation * More than 1 week since prior colony-stimulating factors (e.g., filgrastim \[G-CSF\], sargramostim \[GM-CSF\], or epoetin alfa) * At least 3 weeks since prior myelosuppressive anticancer biologic therapy * No concurrent routine colony-stimulating factors Chemotherapy * At least 3 weeks since prior myelosuppressive anticancer chemotherapy (6 weeks for nitrosoureas or mitomycin) and recovered Endocrine therapy * Concurrent corticosteroids allowed provided dose is stable or decreasing for ≥ 1 week before study entry Radiotherapy * At least 3 months since prior craniospinal irradiation ≥ 18 Gy * At least 2 weeks since prior focal irradiation to the primary tumor and/or symptomatic metastatic sites Surgery * Not specified Other * At least 7 days since prior nonmyelosuppressive anticancer therapy * At least 7 days since prior investigational agents * Concurrent enzyme-inducing anticonvulsant drugs allowed * No other concurrent anticancer or experimental agents or therapies