- Phase I: Patients undergo radiotherapy once daily 5 days a week and receive oral temozolomide once daily for approximately 6½ weeks. Patients also receive arsenic trioxide IV over 1-4 hours once daily, 5 days a week in week 1 and then twice a week in weeks 2-7. Beginning within 3-5 weeks after completion of radiotherapy, patients receive oral temozolomide once daily on days 1-5. Treatment with temozolomide repeats every 28 days for up to 1 year in the absence of disease progression and unacceptable toxicity.