Lobradimil and Carboplatin in Treating Children With Brain Tumors

DISEASE CHARACTERISTICS: * Histologically confirmed childhood brain tumor that is recurrent or refractory or for which no standard chemotherapy exists * High-grade glioma (anaplastic astrocytoma or glioblastoma multiforme) (High-grade glioma stratum closed to accrual as of 01/08/2002) * Low-grade glioma * Medulloblastoma/primitive neuroectodermal tumor (PNET) * Ependymoma * Brainstem tumor or visual pathway glioma (with radiographic evidence only) (Brainstem glioma stratum closed to accrual as of 12/21/2000) * Evidence of recurrent or progressive disease after front-line therapy documented as an increase in tumor size or appearance of new lesion(s) on MRI * Patients who did not previously receive radiotherapy as front-line therapy are eligible at time of second recurrence if the first recurrence was treated with radiotherapy only * Measurable disease in at least 2 dimensions by MRI * Diffuse meningeal involvement not considered measurable if it is the only site of disease * Disease must not be limited to the meninges * No metastases outside of the CNS PATIENT CHARACTERISTICS: Age: * 21 and under at diagnosis Performance status: * ECOG 0-2 Life expectancy: * At least 8 weeks Hematopoietic: * Absolute granulocyte count at least 1,000/mm\^3 * Hemoglobin at least 8.0 g/dL (transfusion allowed) * Platelet count at least 100,000/mm\^3 Hepatic: * Bilirubin less than 1.5 times upper limit of normal (ULN) * SGPT no greater than 2.5 times ULN * No significant hepatic illness Renal: * Creatinine within limits as defined below by age: * Age 5 and under: less than 1.2 mg/dL * Age 6 to 10: less than 1.5 mg/dL * Age 11 to 15: less than 1.8 mg/dL * Age 16 and over: less than 2.4 mg/dL Cardiovascular: * No significant cardiac illness Pulmonary: * No significant pulmonary illness Other: * No significant systemic illness or organ dysfunction that would preclude study * No allergic reaction to platinum-containing compounds * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception PRIOR CONCURRENT THERAPY: Biologic therapy: * At least 72 hours since filgrastim (G-CSF) * No concurrent biologic therapy for brain tumor Chemotherapy: * See Disease Characteristics * No prior carboplatin or lobradimil * No more than 1 prior chemotherapy regimen for high-grade glioma, low-grade glioma, or ependymoma * No more than 2 prior chemotherapy regimens for medulloblastoma/PNET * At least 4 weeks since prior nitrosoureas (2 weeks if also received stem cell/bone marrow rescue) * At least 2 weeks since any other prior myelosuppressive chemotherapy and recovered * No other concurrent chemotherapy for brain tumor Endocrine therapy: * Concurrent corticosteroids for management of tumor-related edema allowed Radiotherapy: * See Disease Characteristics * At least 6 weeks since prior radiotherapy to measurable disease and recovered * No concurrent radiotherapy for brain tumor Surgery: * No concurrent surgery except for ventriculo-peritoneal shunt placement or revision Other: * At least 24 hours since prior vasodilating agents, angiotensin-converting enzyme inhibitors, calcium channel blockers, or beta-blockers