Temozolomide, Vincristine, and Irinotecan in Treating Young Patients With Refractory Solid Tumors

DISEASE CHARACTERISTICS: * Histologically confirmed\* malignant solid tumor, including brain tumor, at original diagnosis or relapse * Refractory disease NOTE: \*Histologic confirmation not required for intrinsic brain stem tumors * Measurable or evaluable disease * No known curative therapy OR therapy proven to prolong survival with an acceptable quality of life exists * No known bone marrow metastases PATIENT CHARACTERISTICS: Age * 1 to 21 Performance status * Lansky 50-100% (for patients ≤ 10 years of age) * Karnofsky 50-100% (for patients \> 10 years of age) Life expectancy * Not specified Hematopoietic * Absolute neutrophil count ≥ 1,000/mm\^3 * Platelet count ≥ 100,000/mm\^3 (transfusion independent) * Hemoglobin ≥ 8.0 g/dL (RBC transfusions allowed) Hepatic * ALT ≤ 110 U/L (upper limit of normal \[ULN\] for ALT is 45 U/L) * Bilirubin ≤ 1.5 times ULN * Albumin ≥ 2 g/dL Renal * Creatinine clearance or radioisotope glomerular filtration rate ≥ 70 mL/min OR * Creatinine based on age as follows: * No greater than 0.8 mg/dL (for patients ≤ 5 years of age) * No greater than 1.0 mg/dL (for patients 6 to 10 years of age) * No greater than 1.2 mg/dL (for patients 11 to 15 years of age) * No greater than 1.5 mg/dL (for patients \> 15 years of age) Other * Not pregnant or nursing * Negative pregnancy test * Fertile patients must use effective contraception * Neurologic deficits in patients with CNS tumors must be stable for ≥ 1 week prior to study entry * No uncontrolled infection * No documented allergy to cephalosporins or dacarbazine PRIOR CONCURRENT THERAPY: Biologic therapy * Recovered from prior immunotherapy * At least 3 months since prior stem cell transplantation or rescue without total-body irradiation * No evidence of active graft-versus-host disease * At least 7 days since prior antineoplastic biologic agents * At least 7 days since prior hematopoietic growth factors * No concurrent biologic therapy or immunotherapy * No concurrent prophylactic filgrastim (G-CSF) during the first course of study treatment Chemotherapy * Recovered from prior chemotherapy * Prior temozolomide, vincristine, irinotecan, or topotecan allowed * No prior coadministration of temozolomide and irinotecan * No disease progression during treatment with either irinotecan or temozolomide * More than 3 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosoureas) * No other concurrent chemotherapy Endocrine therapy * Patients with CNS tumors must be on a stable or decreasing dose of dexamethasone for ≥ 7 days prior to study entry Radiotherapy * Recovered from prior radiotherapy * At least 6 months since prior total-body irradiation, craniospinal radiotherapy, or radiotherapy to ≥ 50% of the pelvis * At least 6 weeks since other prior substantial bone marrow radiotherapy * At least 2 weeks since prior local palliative radiotherapy (small port) * No concurrent radiotherapy Surgery * Not specified Other * No other concurrent investigational drugs * No other concurrent anticancer therapy * No concurrent enzyme-inducing anticonvulsants, including any of the following: * Phenobarbital * Phenytoin * Carbamazepine * Oxcarbazepine * No concurrent administration of any of the following: * Rifampin * Voriconazole * Itraconazole * Ketoconazole * Aprepitant * Hypericum perforatum (St. John's wort) * No concurrent treatment for clostridium difficile infection