Speciation of arsenic trioxide metabolites in peripheral blood and bone marrow from an acute promyelocytic leukemia patient

Abstract

Background: Speciation of arsenic trioxide (ATO) metabolites in clinical samples such as peripheral blood (PB) from acute promyelocytic leukemia (APL) patients has been conducted. However, speciation of arsenicals in bone marrow (BM) has not yet been performed. Profiles of arsenic speciation in plasma of BM were thus investigated and compared with those of PB plasma from a relapsed APL patient. The total arsenic concentrations in high molecular weight fraction (HMW-F) of BM and PB plasma were also determined.

Methods: Response assessment was evaluated by BM aspirate examination and fluorescence in situ hybridization analysis. The analyses of total arsenic concentrations and speciation were preformed by inductively coupled plasma mass spectrometry (ICP-MS), and high-performance liquid chromatography (HPLC)/ICP-MS, respectively.

Results: Response assessment showed that the patient achieved complete remission. The total arsenic concentrations in BM plasma increased with time during the consecutive administration. The PB plasma concentrations of methylated arsenic metabolites substantially increased after the start of administration, while those of inorganic arsenic were still kept at a low level, followed by substantially increase from day-14 after administration. The arsenic speciation profiles of PB plasma were very similar to those of BM plasma. Furthermore, the total arsenic concentrations of HMW-F in BM plasma were much higher than those in PB plasma.

Conclusions: The behaviors of arsenic speciation suggested for the first time that arsenic speciation analysis of PB plasma could be predicative for BM speciation, and showed relatively higher efficiency of drug metabolism in the patient. These results may further provide not only significance of clinical application of ATO, but also a new insight into host defense mechanisms in APL patients undergoing ATO treatment, since HMW proteins-bound arsenic complex could be thought to protect BM from the attack of free arsenic species.

Figure 1

Profiles of total arsenic concentrations in PB RBCs, PB plasma and BM plasma collected during the remission induction therapy. Symbols (●), (■) and (▲) show the total arsenic concentrations in PB RBCs, PB plasma and BM plasma, respectively. PB, peripheral blood; RBCs, red blood cells; BM, bone marrow.

Figure 2

Chromatogram of standard arsenic species. The separation was performed on CAPCELL PAC C18 MG II with 10 mM butane sulfonic sodium, 4 mM malonic acid, 4 mM tetramethylammonium hydroxide, and 0.5% methanol (pH 2.0). The signal peaks are as follows: As(V) (1), As(III) (2), MA(V) (3), DMA(V) (4), and AB (5).

Figure 3

Profiles of concentrations of arsenic species in PB plasma collected during the remission induction therapy. Blood samples were collected before the treatment start (day -1), and 3, 7, 10, 14, 17, 21, 28, 42, 56 days after the start of administration. The concentrations of arsenic species in plasma were determined with HPLC/ICP-MS as described in "Patient and Methods." A merged representative chromatogram obtained from the analyses of a plasma sample collected on day 14 and the same plasma sample spiked with As(V), As(III), MA(V), DMA(V), and AB is shown in Figure 3(A). The signal peaks are as follows: As(V) (1), As(III) (2), MA(V) (3), DMA(V) (4), and AB (5). The concentrations of arsenic species calculated from these chromatograms are shown in Figure 3(B). (●): As(V); (■): As(III); (▲): MA(V); (♦): DMA(V); (O): AB.

Figure 4

Profiles of concentrations of arsenic species in BM plasma collected during the remission induction therapy. BM aspirates were collected before the treatment start (day -1), and 14, 28, 42, and 56 days after the start of administration. The concentrations of arsenic species in plasma were determined with HPLC/ICP-MS as described in "Patient and Methods." Similar to Figure 3 (A), identification of arsenic species by a spike test was conducted using a plasma sample collected on day 14 and was shown in Figure 4 (A). The concentrations of arsenic species calculated from these chromatograms are shown in Figure 4 (B). (●): As(V); (■): As(III); (▲): MA(V); (♦): DMA(V); (O): AB.

Figure 5

Comparison of arsenic speciation profiles between PB plasma and BM plasma. The columns of Before start, Day-14, Day-28, Day-42 and Day-56 represent the speciation profiles of PB and BM plasma collected before the treatment start (day -1), and 14, 28, 42, and 56 days after the start of administration, respectively. The open column, gray column, black column, hatched column and vertical striped column show As(V), As(III), MA(V), DMA(V) and AB, respectively.

Figure 6

Total arsenic concentrations in HMW-F and LMW-F of PB and BM plasma. Blood samples and BM aspirations were collected before the treatment start (day -1), and 14, 28, 42, and 56 days after the start of administration. HMW-F of PB and BM plasma were prepared and subjected to total arsenic determination as described in "Patient and Methods". The total arsenic concentrations in LMW-F of PB and BM plasma were obtained by subtraction of that in HMW-F from the total arsenic concentrations in PB and BM plasma.