Irinotecan in Treating Children With Refractory Solid Tumors

Inclusion Criteria: Histologically or cytologically confirmed CNS or solid tumors recurrent or refractory to standard therapy Solid tumors: Neuroblastoma Ewing's Sarcoma/peripheral primitive neuroectodermal tumor (PNET) Osteosarcoma Rhabdomyosarcoma Other extracranial solid tumors CNS tumors: Medulloblastoma/PNET Ependymoma Brain stem glioma Other CNS tumor Intrinsic brain stem tumor (biopsy required only if previously treated with radiosurgery) Classic optic glioma (histologic requirement waived) Measurable disease by imaging studies No lesions assessable only by radionuclide scan Previously irradiated lesions used to evaluate tumor response must show evidence of an interim increase in size Performance status - Karnofsky 50-100% if more than 10 years old Performance status - Lansky 50-100% if 10 years or younger At least 8 weeks Absolute neutrophil count greater than 1,000/mm^3 Platelet count greater than 100,000/mm^3 Hemoglobin greater than 8 mg/dL Inadequate peripheral blood counts due to bone marrow infiltration allowed Bilirubin no greater than 1.5 mg/dL SGPT less than 5 times normal Creatinine normal Glomerular filtration rate at least 70 mL/min No severe uncontrolled infection Not pregnant or nursing Negative pregnancy test Fertile patients must use effective contraception during and for 6 months after study At least 3 weeks since prior immunotherapy and recovered No concurrent biologic therapy At least 3 weeks since prior chemotherapy (8 weeks since prior nitrosoureas) and recovered No more than 2 prior chemotherapy regimens No other concurrent chemotherapy Prior topotecan allowed No prior irinotecan Concurrent dexamethasone for brain tumor patients allowed if on a stable or decreasing dose for at least 2 weeks prior to study At least 3 weeks since prior endocrine therapy No other concurrent endocrine therapy See Disease Characteristics At least 8 weeks since prior extended radiotherapy (including evaluable lesions) and recovered No prior total body radiotherapy No concurrent radiotherapy See Disease Characteristics At least 3 weeks since prior investigational agents No other concurrent investigational agents No concurrent anticonvulsants No concurrent medications that would interfere with the P-450 enzyme system function (e.g., erythromycin, cimetidine, fluconazole)