Speciation analysis of arsenic in urine samples from APL patients treated with single agent AsO by HPLC-HG-AFS.

Arsenic trioxide [AsO, arsenite (As) in solution] has been applied successfully for the treatment of acute promyelocytic leukemia (APL). The arsenic speciation analysis of urine is critical to reveal the metabolic mechanism and the relationship between arsenic species and the clinical response. To characterize the arsenic species in urine, a simple and robust HPLC-HG-AFS method was developed and validated to quantify the levels of arsenic species [As and its metabolites, monomethylarsonic acid (MMA), dimethylarsinic acid (DMA), and arsenate (As)] in urine samples from 66 patients with APL. Patients received AsO (0.16 mg/kg/day) via continuous slow-rate infusion or conventional infusion. Urine samples were collected at steady state before the start of the next daily administration. The relative proportions (median) of arsenic species in urine were: As, 33.00% (IQR: 24.34%-46.82%); DMA, 36.42% (IQR: 25.82%-51.98%); MMA, 23.89% (IQR: 19.52%-27.19%); and As, 2.22% (IQR: 1.293%-3.665%). The levels and proportions of arsenic species vary widely among individual patients. DMA and un-metabolized As were the dominant arsenic compounds excreted from the urine of patients with APL treated with AsO. As was the least abundant arsenic species in all urine samples. Good positive correlations were found between the levels and proportions of arsenic species in urine and those in plasma; thus, urinary arsenic can reflect the levels of arsenic in plasma. Urinary arsenic is a critical biomarker to evaluate the metabolism and toxicity of arsenic in the clinical application of AsO.