PH I Addition of Farnesyl Transferase Inhibitor to Temozolomide for Pts w Gr 3 & 4 Malignant Gliomas

2 separate strata accrued independently: Stratum 1-pts receiving CYP3A4-inducing anticonvulsants. Stratum 2-pts on non CYP3A4-inducing anticonvulsants or pts not on any anti-convulsants. Each strata treated \& escalated independent of each other. Temozolomide administered orally at dose of 150 mg/m2 daily for 5 days, at bedtime, for 1st cycle \& escalated to 200 mg/m2 daily for 5 days, at bedtime during subsequent cycles if tolerated. Treatment cycles repeated every 4wks following doses of Temozolomide from previous cycle. SCH 66336 administered orally twice daily, approximately every 12hrs. Except as specifically noted, pts advised to take capsules wh morning \& evening meals, with approximately 240ml of non-carbonated water. Initial doses will be 125mg BID for stratum 1 \& 75mg BID for stratum2. Treatment cycles repeated every 4 wks following dose of Temozolomide from previous cycle.