- At the time of registration: Patients must have recovered from the toxic effects of prior therapy: > 10 days from any noncytotoxic investigational agent, >28 days from prior cytotoxic therapy or Avastin, >14 days from vincristine, >42 days from nitrosoureas, >21 days from procarbazine administration, and >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.