PRIOR CONCURRENT THERAPY: Biologic therapy: No acute toxic effects from prior immunotherapy No prior allogeneic or autologous bone marrow transplantations within 3 months of study Chemotherapy: No prior systemic CNS directed chemotherapy within 3 weeks of study No prior nitrosourea within 6 weeks of study No prior intrathecal chemotherapy within 1 week of study No acute toxic effects from prior chemotherapy No prior DTC 101 Concurrent systemic chemotherapy for management of primary cancer allowed Concurrent dexamethasone with systemic chemotherapy regimen allowed No concurrent chemotherapy for leptomeningeal disease No concurrent high dose methotrexate, high dose cytarabine, mercaptopurine, thiotepa, fluorouracil, and topotecan Endocrine therapy: Concurrent prednisone therapy with systemic chemotherapy allowed Radiotherapy: No prior craniospinal irradiation within 8 weeks of study No acute toxic effects from prior radiotherapy Concurrent local radiation therapy allowed No concurrent whole brain or craniospinal radiotherapy Surgery: Not specified Other: At least 2 weeks since investigational drugs and recovered No other concurrent investigational drugs Concurrent antibiotic therapy allowed