 - Patients must have recovered from the toxic effects of prior therapy: 4 weeks 28 days from any investigational agent, 4 weeks 28 days from prior cytotoxic therapy, two weeks 14 days from vincristine, 6 weeks 42 days from nitrosoureas, 3 weeks 21 days from procarbazine administration, and 1 week 7 days for non-cytotoxic agents, e.g., interferon, tamoxifen, thalidomide, cis-retinoic acid, etc. radiosensitizer does not count; any questions related to the definition of non-cytotoxic agents should be directed to the study chair 