Arsenic trioxide - An old drug rediscovered.

Over the last 17 years, clinical trials conducted worldwide have demonstrated the efficacy of arsenic trioxide (As(2)O(3)) in the treatment of relapsed acute promyelocytic leukemia (APL). Currently, the role of As(2)O(3) in front-line therapy is under investigation. Recent trials in the US have demonstrated that the addition of As(2)O(3) to standard treatment regimens improves survival outcomes in patients with APL and may allow a reduction in cytotoxic chemotherapy exposure. As(2)O(3) has also shown efficacy in other malignancies, particularly multiple myeloma and myelodysplastic syndromes. Therapeutic doses of As(2)O(3) are well tolerated, with no evidence of long-term toxicity. Adverse events include APL differentiation syndrome, electrocardiographic abnormalities, and mild elevations in liver enzymes. This review highlights trials investigating the role of As(2)O(3) in induction and consolidation for newly diagnosed APL, as well as its role in other hematologic malignancies. The chemistry, mechanisms of action, and clinical side effects of As(2)O(3) are also discussed.