OUTLINE: This is a dose-escalation study. Patients receive arsenic trioxide IV over 1-4 hours on days 1-25. Courses repeat every 3-5 weeks in the absence of disease progression or unacceptable toxicity. Cohorts of 4-6 patients receive escalating doses of arsenic trioxide until the maximum tolerated dose (MTD) is determined. The MTD is defined as the dose at which no more than 1 of 6 patients experiences dose-limiting toxicity. Patients are followed for 1 month.