10. Patients must have recovered from the toxic effects of prior therapy to < grade 2 non hematological or grade 2 or lesser hematological toxicity per CTC ver 4 (except deep vein thrombosis): 4 weeks from prior cytotoxic therapy and/or at least two weeks from vincristine, 6 weeks from nitrosoureas, 3 weeks from procarbazine administration, and 1 week for non-cytotoxic agents, e.g., interferon, tamoxifen, cis-retinoic acid, etc. (radiosensitizer does not count). Patients who receive anticancer agents for non-therapeutic purposes unrelated to this study