Combination Chemotherapy With or Without Sodium Thiosulfate in Preventing Low Platelet Count While Treating Patients With Malignant Brain Tumors

PRIMARY OBJECTIVE: I. Determine the effect of delayed administration of sodium thiosulfate on the rates of platelet toxicity (i.e. platelet count less than 20,000), in subjects with high-grade glioma undergoing treatment with carboplatin, cyclophosphamide and etoposide/etoposide phosphate. SECONDARY OBJECTIVES: I. Assess tumor response in subjects with high-grade glioma undergoing treatment with carboplatin, cyclophosphamide and etoposide/etoposide phosphate, with or without delayed sodium thiosulfate. II. Assess the effect of delayed administration of sodium thiosulfate on granulocyte and erythrocyte counts, in subjects undergoing treatment with carboplatin, cyclophosphamide and etoposide/etoposide phosphate. III. Assess hearing changes, if any, at the higher frequencies in the standard testing range (4000 and 8000 Hertz \[Hz\]), and at higher frequencies above standard testing (9000 to 16000 Hz). IV. Assess quality of life in subjects undergoing treatment with carboplatin, cyclophosphamide and etoposide phosphate. OUTLINE: Patients are randomized to 1 of 2 treatment arms. ARM I: Patients receive cyclophosphamide intravenously (IV), etoposide phosphate IV, and carboplatin intra-arterially (IA) over 10 minutes on day 1. ARM II: Patients receive cyclophosphamide IV, etoposide phosphate IV, and carboplatin IA as in Arm I. Patients also receive sodium thiosulfate IV over 15 minutes 4 and 8 hours after carboplatin. In both arms, treatment repeats every 4 weeks for up to 12 courses in the absence of disease progression or unacceptable toxicity. After completion of study treatment, patients are followed up every 3 months for 1 year, every 6 months for 2 years, and then annually thereafter.