- Must have recovered from the acute neurotoxic effects of all prior chemo, immuno, or radiotherapy and must be without uncontrolled significant systemic illness (e.g. infection). Must not have received any systemic CNS-directed therapy within 3 weeks or craniospinal irradiation within 8 weeks prior to starting treatment on study. Must not have received any intrathecal therapy within 1 week prior to starting treatment on study.