Determination of arsenic metabolites in patients with newly diagnosed acute promyelocytic leukemia treated with arsenic trioxide.

The efficacy of arsenic trioxide (ATO) in the treatment of acute promyelocytic leukemia (APL) is widely accepted. It is necessary to determine the concentration of arsenic due to its toxicity. The profiles of arsenic speciation in patients with relapsed or refractory APL have been demonstrated in few reports. Arsenic metabolite concentrations in the plasma of patients with newly diagnosed APL during the first course of arsenic remission induction therapy were determined, and the complicated change pattern of these metabolite concentrations in this phase is described for the first time in this study. We demonstrated that the concentration of trivalent inorganic arsenic (As(III)), which is regarded as the most effective and toxic, was much lower than those of other metabolites. Concentrations of the same arsenic metabolites were obviously distinct among various individuals. We infer that determination of the metabolites separately is necessary, and cannot be replaced by total arsenic determination. In addition, the amount of methylated metabolites of arsenic increased during the first course of ATO therapy, and these metabolites might therefore play an increasingly important role. Further research should be carried out to study the relationship between arsenic metabolite concentrations and efficacy, as well as side effects in patients with APL treated with ATO.