6. Last dose of chemotherapy or experimental therapy more than 4 weeks (6 weeks in the case of nitrosourea) prior to enrollment date; unless the last therapy consisted of an oral agent whose average half life is known to be less than 48 hours in which case only 2 weeks need to have elapsed. Regardless of the therapy, any toxicity greater than Common Terminology Criteria in Adverse Events (CTCAE) grade 1 from previous anti-cancer therapy must have been resolved.