PRIOR CONCURRENT THERAPY: Biologic therapy: At least 1 week since prior biologic therapy and recovered At least 1 week since prior growth factor therapy At least 6 months since prior peripheral blood stem cell transplantation and no evidence of graft-vs-host disease For less heavily pretreated stratum: No prior peripheral blood stem cell transplantation Chemotherapy: At least 4 weeks since prior myelosuppressive chemotherapy (6 weeks for nitrosoureas) and recovered No prior ecteinascidin 743 For less heavily pretreated stratum: No more than 2 prior chemotherapy regimens Endocrine therapy: Not specified Radiotherapy: At least 2 weeks since prior local palliative radiotherapy (small port) At least 6 weeks since prior substantial bone marrow radiotherapy At least 6 months since prior craniospinal radiotherapy or radiotherapy to 50% or greater of pelvis For less heavily pretreated stratum: No prior craniospinal irradiation of 18Gy or greater No prior irradiation to greater than 50% of pelvis Recovered from toxic effects of prior radiotherapy Surgery: Not specified Other: No concurrent foods or medication that interferes with P-450 metabolism Anticonvulsants allowed