Patients receive arsenic trioxide IV over 1-2 hours for 5 days and oral ascorbic acid once daily for 5 days during week 1. Patients then receive arsenic trioxide and ascorbic acid twice a week in weeks 2-12. Patients also receive oral dexamethasone once daily for 5 days in weeks 1, 5, 9, and 12 and oral thalidomide once or twice daily in weeks 1-12. Courses repeat every 12 weeks in the absence of disease progression or unacceptable toxicity.