Arsenic methylation metabolism and liver injury of acute promyelocytic leukemia patients undergoing arsenic trioxide treatment

Although arsenic is effective in the treatment of acute promyelocytic leukemia (APL), as a well-known environmental toxicant, the side effects of arsenic treatment and arsenic methylation metabolism of the patients are rarely reported. In this manuscript, we investigated 23 APL patients treated with 10 mg arsenic trioxide daily, detected the arsenic metabolites in urine samples collected on the 0, 10th, and 20th day of arsenic treatment. At the same time, liver function and blood routine examination were also investigated in these APL patients. We found that, urinary monomethylated arsenic proportion (MMA%) increased, but dimethylated arsenic proportion (DMA%), the first methylation ratio (FMR) and the secondary methylation ratio (SMR) decreased with consecutive administration of arsenic trioxide. After adjustment for age impact, no statistical difference was observed in urinary arsenic concentrations and arsenic methylation capacity between male and female at the same treatment time point. During arsenic trioxide treatment of APL, transient elevation of serum aminotransferases was found in the blood samples, which indicated that liver injury occurred and probably reversible. Leukocytosis developed in 5 of the 23 patients with the administration of arsenic trioxide. No statistical difference was observed in the other blood routine examination parameters. These results demonstrated that the capacity of arsenic methylation decreased and transient liver injury occurred during arsenic trioxide treatment of APL, which indicated that the side effects of clinical arsenic treatment can not be ignored.

Arsenic speciation in urine from acute promyelocytic leukemia patients undergoing arsenic trioxide treatment

Arsenic has been used successfully in clinical trials for treating acute promyelocytic leukemia (APL). Although sublethal doses of inorganic arsenic are used, little is known about the pharmacokinetics and metabolism of the high levels of arsenic in APL patients. To fill this important gap, this study describes the speciation of arsenic in urine from four APL patients treated with arsenic. Each patient was injected daily with an arsenite (As(III)) solution that contained 10 mg of As(2)O(3) precursor. Speciation analysis of the patient urine samples collected consecutively for 48 h, encompassing two intravenous injections of arsenic, revealed the presence of monomethylarsonous acid (MMA(III)), dimethylarsinous acid (DMA(III)), monomethylarsonic acid (MMA(V)), and dimethylarsinic acid (DMA(V)). The intermediate methyl arsenic metabolites, MMA(III) and DMA(III), were detected in most urine samples from all of the patients when a preservative, diethyldithiocarbomate, was added to the urine samples to stabilize these trivalent arsenic species. The major arsenic species detected in the urine samples from the patients were As(III), MMA(V), and DMA(V), accounting for >95% of the total arsenic excreted. The relative proportions of As(III), As(V), MMA(V), and DMA(V) in urine samples collected 24 h after the injections of As(III) were 27.6 +/- 6.1, 2.8 +/- 2.0, 22.8 +/- 8.1, and 43.7 +/- 13.3%, respectively. The relatively lower fraction of the methylated arsenic species in these APL patients under arsenic treatment as compared with that from the general population exposed to much lower levels of arsenic suggests that the high levels of As(III) inhibit the methylation of arsenic (inhibits the formation of methyl arsenic metabolites). The arsenic species excreted into the urine accounted for 32-65% of the total arsenic injected. These results suggest that other pathways of excretion, such as through the bile, may play an important role in eliminating (removing) arsenic from the human body when challenged by high levels of As(III).

[Pharmacokinetics of intravenous arsenic trioxide in the treatment of acute promyelocytic leukemia]

OBJECTIVE

In order to study the pharmacokinetics and metabolism of arsenic trioxide (As22O3), and its major side effects.

METHODS

The clinical pharmacokinetics of intravenous As2O3 in 8 relapsed acute promyelocytic leukemia (APL) patients were studied by Gas-phase chromotography.

RESULTS

(1) After 2 hour intravenous drips of 10mg As2O3, drug plasma maximal concentration (Cpmax) was 0.94 +/- 0.37mg/L(x +/- s), time to peak concentration (Tp) was 4hrs, T1/2 alpha and T1/2beta were 0.89 +/- 0.29hrs and 12.13 +/- 3.31hrs, respectively, apparent volume of distribution (Vc) was 3.83 +/- 0.45L, system clearance (CLs) was 1.43 +/- 0.17L/h and area under curve (AUC) was 7.25 +/- 0.97mg x h/L. Importantly, the continuous administration of As2O3 did not alter the pharmacokinetic behaviors. (2) During As2O3 therapy, 24-hour arsenic content in urine accounted for 1%-8% of the total dose (10mg) per day. And it decreased gradually after drug withdrawal. (3) Arsenic contents in nail and hair were increased continuously during As2O3 therapy. The peak concentrations could be five to seven-fold higher than that pre-treatment. It also decreased gradually after drug with drawal.

CONCLUSION

As2O3 is a relatively safe and effective drug in the treatment of APL patients, in spite of certain accumulation in some tissues.

Epidermal growth factor in acute promyelocytic leukemia treated with retinoic acid

We studied 18 patients with acute promyelocytic leukaemia and 13 with relapsed APL. We found a significantly elevated EGF in acute leukaemia, especially in APL, being 418.59 +/- 19.2 micrograms in the 24-h urine that was much higher than that of the normal controls. When eight APL patients achieved complete remission by RA treatment, the EGF value decreased to 149.9 +/- 27.3 micrograms in the 24-h urine near to normal. In 13 patients with relapsed APL, EGF rose to 446.9 +/- 82.6 micrograms in the 24-h urine. Most interestingly, this elevated EGF could be detected before the relapse by 5 +/- 0.84 months in seven out of eight APL with relapse. We suggest that the unaccountably elevated EGF during remission period may be an indicator of the occurrence of relapse.