Background: Multiple myeloma is a plasma cell dyscrasia characterized by proliferation of plasma cells in bone marrow associated with the production of monoclonal immunoglobulins. In recent years, the use of arsenic trioxide, formerly approved for treatment of acute promyelocytic leukemia has been considered for refractory myeloma treatment. This study was designed and carried out to evaluate the efficacy and possible side effects of ATO on patients with refractory multiple myeloma.

Methods: This study carried out on myeloma patients whose diseases were at least refractory to two standard treatment regimens conducted in Ghazi Tabatabaei Hospital in Tabriz- Iran. Arsenic trioxide was administered as an intravenous infusion at a dose of 0.25 mg/kg/d for 5 d/week during the first two consecutive weeks of each 4-week cycle with two week rest. Patients who completed one 4-weak cycle were evaluated for response to treatment.

Results: Twelve patients with refractory disease to conventional treatment regimens received arsenic trioxide. The response to the treatment assessed based on the amount of serum proteins electrophoresis of the 10 patients. Stable disease observed in four patients (33%), progressive disease in five patients (41.6%), complete response in one (3.8%) and the remaning two patients could not be assessed for response (because of increased liver enzymes after the first week). One patient completed six cycles. Some adverse events such as: increase liver enzymes and serum creatinine, neutropenia, pruritus, nausea, vomiting, lower extremities edema, and noninfectious diarrhea were observed.

Conclusions: The use of arsenic trioxide is promising in treatment of refractory multiple myeloma.