Ph. I Temozolomide + O6-BG + Irinotecan in Treatment of Pts w Recurrent / Progressive Cerebral Anaplastic Gliomas

2 separate strata accrued independently: Stratum 1-pts receiving Dilantin, Tegretol or phenobarbital. Stratum 2-pts on anti-convulsants other than Dilantin, Tegretol/phenobarbital/pts not on any anti-convulsants. O6-BG administered intravenously 120mg/m2, over 1hr, prior to administration of Temozolomide on day 1 of 21day cycle. O6-BG administered intravenously 30mg/m2/day, over 48hrs, immediately after completion of CPT-11 infusion on day 1 of 21-day cycle. Temozolomide administered orally 355mg/m2 within 60 mins of end of 1hr O6-BG infusion. Treatment cycles may be repeated every 3wks following dose of Temozolomide from previous cycle. CPT-11 administered intravenously in fasting state over 90mins. CPT-11 infusion will begin 1hr after Temozolomide administration. Initial doses 60mg/m2 for stratum 1 \& 40mg/m2 for stratum2. Treatment cycles repeated every 3 wks following dose of CPT-11 from previous cycle.