Melphalan, Arsenic Trioxide, and Ascorbic Acid in Treating Patients With Relapsed or Refractory Multiple Myeloma

RATIONALE: Drugs used in chemotherapy, such as melphalan, arsenic trioxide, and ascorbic acid, work in different ways to stop cancer cells from dividing so they stop growing or die. Arsenic trioxide and ascorbic acid may also help melphalan kill more cancer cells by making them more sensitive to the drugs. PURPOSE: This phase II trial is studying how well giving melphalan together with arsenic trioxide and ascorbic acid works in treating patients with relapsed or refractory multiple myeloma.

OBJECTIVES: Primary * Determine the time to progression in patients with relapsed or refractory multiple myeloma (MM) treated with melphalan, arsenic trioxide, and ascorbic acid. * Determine the response rate (combined complete response, partial response, and minimal response) in patients treated with this regimen. * Determine the safety and tolerability of this regimen in these patients. Secondary * Determine the time to response and overall survival of patients treated with this regimen. * Determine the effects of this regimen on renal failure associated with MM in these patients. OUTLINE: This is an open-label, non-randomized, multicenter study. Patients receive oral melphalan once daily on days 1-4 of week 1 and arsenic trioxide (ATO) IV over 1-2 hours and ascorbic acid IV over 15 minutes on days 1-4 of week 1 and then twice weekly during weeks 2-5. Treatment repeats every 6 weeks for up to 6 courses in the absence of disease progression or unacceptable toxicity. Patients with disease progression any time after course 1 also receive oral prednisone once daily on days 1-4 and 22-25 of each course. Patients achieving a complete response after 6 courses of therapy undergo bone marrow biopsy and receive no further therapy. Patients achieving stable disease or a partial response after 6 courses of therapy continue to receive ATO and ascorbic acid once weekly. Patients are followed every 3 months. PROJECTED ACCRUAL: A total of 65 patients will be accrued for this study.