Monomethylarsonous acid binds to Cys-104α and Cys-112ß of hemoglobin in acute promyelocytic leukemia patients treated with arsenic trioxide.

Arsenic trioxide (As2O3) has prominent effect in treating acute promyelocytic leukemia (APL). Identification of arsenic-binding proteins has gained attention for their important biological functions. However, none has been published concerning the binding mechanism of arsenic with hemoglobin (Hb) in APL patients after treatment of As2O3. The present study discloses the binding sites of arsenic on Hb in APL patients. Concentrations of inorganic arsenic (iAs), monomethyl arsenic (MMA), and dimethyl arsenic (DMA) in erythrocytes of APL patients were quantified using HPLC-inductively coupled plasma-mass spectroscopy (HPLC-ICP-MS). Hb-bound arsenic was identified by size-exclusion chromatography ICP-MS. The binding sites of arsenic on Hb were determined by mass spectrometry (MS). The concentration trend of arsenic species in erythrocytes of 9 APL patients treated with As2O3 was iAs>MMA>DMA, and MMA was the predominant methylated arsenic metabolite. Size-exclusion chromatography separation of free and protein-bound arsenic by simultaneous monitoring of 57Fe and 75As demonstrated the presence of Hb-bound arsenic. MS information suggested monomethylarsonous (MMAIII) was the dominant arsenic bound to Hb, and further identified that Cys-104α and Cys-112ß were two binding sites of MMAIII in Hb. MMAIII binding to Cys-104α and Cys-112ß was responsible for arsenic accumulation in erythrocytes of APL patients. This interaction may contribute to understand the therapeutic effect of As2O3 as an anticancer drug and its toxicity on APL patients.

Sacubitril/valsartan protects against arsenic trioxide induced cardiotoxicity in vivo and in vitro.

The cardiotoxicity induced by arsenic trioxide (ATO) limits its clinical application in acute promyelocytic leukemia treatment. Sacubitril/valsartan (LCZ696) is an effective drug for the treatment of heart failure. In this study, we aimed to investigate the protective effect and mechanisms of LCZ696 against the ATO-induced cardiotoxicity in mice and H9c2 cells. We found that LCZ696 could alleviate the decrease of ejection fraction and fractional shortening induced by ATO, thereby improving mouse cardiac contractile function. LCZ696 could also reduce the myocardial enzyme, resist oxidative stress, mitigate myocardial fibrosis, and ameliorate myocardial structure, thereby alleviating myocardial damage caused by ATO. In addition, LCZ696 could significantly increase the cell viability and reduce the accumulation of reactive oxygen species in ATO-treated H9c2 cells. Besides, in vivo and in vitro studies have been found that LCZ696 could restore the expression of Bcl-2 and reduce Bax and Caspase-3 levels, inhibiting ATO-induced apoptosis. Meanwhile, LCZ696 decreased the levels of IL-1, IL-6, and TNF-α, alleviating the inflammatory injury caused by ATO. Furthermore, LCZ696 prevented NF-κB upregulation induced by ATO. Our findings revealed that LCZ696 has a considerable effect on preventing cardiotoxicity induced by ATO, which attributes to its capability to suppress oxidative stress, inflammation, and apoptosis.

Pharmacokinetics of cefoperazone/sulbactam in critically Ill thrombotic thrombocytopenic purpura patients undergoing therapeutic plasma exchange.

WHAT IS KNOWN AND OBJECTIVES: The aim of this study was to investigate the pharmacokinetics (PK) of cefoperazone (CFP) and sulbactam (SUL) in critically ill thrombotic thrombocytopenic purpura (TTP) patients undergoing therapeutic plasma exchange (TPE). METHODS: Critically ill TTP patients receiving a dose of 3 g CFP/SUL (2.0 g/1.0 g) intravenously every 8 h were included in the study. TPE session began 10 min after the end of CFP/SUL infusion. Serial blood samples were collected at 0, 1, 2, 3, 4, 6 and 8 h at the fourth infusion with TPE and the sixth infusion without TPE. Effluent samples were collected at the effluent port of plasma eliminated at the end of TPE. Concentrations of CFP and SUL in plasma and effluent were measured using LC-MS/MS. PK parameters were calculated based on two-compartment open model. RESULTS: Five critically ill TTP patients receiving CFP/SUL monotherapy were enrolled. T1/2α of CFP and SUL with TPE was 0.62 and 1.30 h, respectively. For CFP, T1/2ß with TPE were significantly higher than those without TPE (5.85 ± 3.16 vs. 4.41 ± 2.74, p = 0.016). Vss with TPE were significantly higher than those without TPE (7.23 ± 0.89 vs. 5.24 ± 0.80 L, p = 0.024). AUC0-8 with TPE were significantly lower compared with those without TPE (1380.98 ± 411.99 vs. 1581.61 ± 500.22 mg*h/L, p = 0.011). Relatively, CLt with TPE were significantly higher than those without TPE (1.56 ± 0.46 vs. 1.37 ± 0.44 L/h, p = 0.010). For SUL, Vss and CLt were higher significantly with TPE than those without TPE (28.11 ± 8.42 vs. 18.87 ± 6.45 L, p = 0.002; 10.74 ± 2.01 vs. 8.60 ± 2.10 L/h, p = 0.048). Mean QPE of CFP and SUL were 344.42 ± 55.37 and 34.65 ± 10.09 mg, respectively. Mean fe% of CFP and SUL were 17.22 ± 2.77% and 3.46 ± 1.01%, respectively. WHAT IS NEW AND CONCLUSION: TPE enhances the clearance of CFP and SUL in critically ill TTP patients. CFP is more likely to be removed than SUL due to its a low V and high Pb. TPE is suggested to begin 1-2 h after the end of CFP/SUL infusion. Plasma concentration monitoring is advised when CFP/SUL must be administered during TPE.

Pharmacokinetic Characteristics, Tissue Bioaccumulation and Toxicity Profiles of Oral Arsenic Trioxide in Rats: Implications for the Treatment and Risk Assessment of Acute Promyelocytic Leukemia.

Oral arsenic trioxide (ATO) has demonstrated a favorable clinical efficiency in the treatment of acute promyelocytic leukemia (APL). However, the pharmacokinetic characteristics, tissue bioaccumulation, and toxicity profiles of arsenic metabolites in vivo following oral administration of ATO have not yet been characterized. The present study uses high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS) to assess the pharmacokinetics of arsenic metabolites in rat plasma after oral and intravenous administration of 1 mg kg-1 ATO. In addition, the bioaccumulation of arsenic metabolites in blood and selected tissues were evaluated after 28 days oral administration of ATO in rats at a dose of 0, 2, 8, and 20 mg kg-1 d-1. The HPLC-HG-AFS analysis was complemented by a biochemical, hematological, and histopathological evaluation conducted upon completion of ATO treatment. Pharmacokinetic results showed that arsenite (AsIII) reached a maximum plasma concentration rapidly after initial dosing, and the absolute bioavailability of AsIII was 81.03%. Toxicological results showed that the levels of aspartate aminotransferase (AST), alanine aminotransferase (ALT), and white blood cells (WBC) in the 20 mg kg-1 d-1 ATO group were significantly increased compared to the control group (p < 0.05). The distribution trend of total arsenic in the rat was as follows: whole blood > kidney > liver > heart. Dimethylated arsenic (DMA) was the predominant bioaccumulative metabolite in the whole blood, liver, and heart, while monomethylated arsenic (MMA) was the predominant one in the kidney. Collectively, these results revealed that oral ATO was rapidly absorbed, well-tolerated, and showed organ-specific and dose-specific bioaccumulation of arsenic metabolites. The present study provides preliminary evidence for clinical applications and the long-term safety evaluation of oral ATO in the treatment of APL.

Evaluation of arsenic species in leukocytes and granulocytes of acute promyelocytic leukemia patients treated with arsenic trioxide.

Concentrations of arsenic metabolites were important to clarify the sensitivity and resistance of APL (acute promyelocytic leukemia) patients to arsenic trioxide (As2O3). Our purpose was to evaluate levels and distributions of arsenic species in leukocytes and granulocytes of APL patients. Inorganic arsenic (iAs), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA) were measured by high performance liquid chromatography coupled inductively coupled plasma mass spectrometry (HPLC-ICP-MS). Leukocytes were collected from 21 patients treated with As2O3 during induction, consolidation, and drug-withdrawal period. The upregulation of granulocytes in induction period was closely related to the differentiation of promyelocytes. Therefore, granulocytes were collected during induction period from 4 APL patients and purified by flow cytometry sorting using a panel of monoclonal antibodies specific for CD45, CD3, CD14, and CD19. The developed HPLC-ICP-MS method was precise and accurate with the limit of quantification of 0.5 ng/mL. During induction, consolidation, and drug-withdrawal period, the general trend of arsenic species was iAs > MMA > DMA (P < 0.05) in leukocytes. iAs was predominant arsenic species with median concentration of 10.84 (6.03-14.62) ng/mL. MMA was major methylated metabolite with median concentration of 0.94 (0.60-2.50) ng/mL. Moreover, arsenicals were detected in leukocytes during drug-withdrawal. In granulocytes, iAs was found during induction period with median concentration of 1.08 ng/mL, while MMA and DMA were not detected. These results showed that iAs was the primary arsenic species in leukocytes and granulocytes from APL patients treated with As2O3. This study suggested that iAs might play a dominant therapeutic role during the whole treatment process of APL.

Effect of renal impairment on arsenic accumulation, methylation capacity, and safety in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide.

Background: Arsenic trioxide (ATO) was successfully applied to treat acute promyelocytic leukemia (APL).Methods: Inorganic arsenic (iAs), monomethylarsonic acid (MMAV) and dimethyarsinic acid (DMAV) in plasma of 143 APL patients with different renal function were determined. Arsenic methylation capacity was evaluated by iAs%, MMAV%, DMAV%, primary methylation index (PMI, MMAV/iAs), and secondary methylated index (SMI, DMAV/MMAV). Arsenic accumulation with administration frequency were explored. Moreover, safety assessments were performed.Results: Compared with normal renal function, MMAV and DMAV concentrations increased 1.5-4 fold in moderate and severe renal impairment groups, iAs increased 1.3-1.7 fold. APL patients with renal impairment showed lower iAs%, but higher DMAV% and PMI in plasma than those with normal renal function (P < 0.05). MMAV, DMAV, and tAs apparently accumulated with administration frequency in moderate and severe renal dysfunction groups. The incidence of QTc interval prolongation and liver injury increased with the increasing severity of renal impairment.Conclusion: Renal dysfunction may increase exposure to arsenic and arsenic accumulation and affect methylation capacity, then the clinical safety in APL patients treated with ATO. Arsenic-level monitoring and dosing regimen adjustment should be considered in APL patients with moderate and severe renal dysfunction.

Monomethylated arsenic was the Major methylated arsenic in Red blood cells of acute promyelocytic leukemia patients treated with arsenic trioxide.

BACKGROUND: Arsenic trioxide (ATO) has been successfully applied in the treatment of acute promyelocytic leukemia (APL). Arsenic metabolites including inorganic arsenic and methylated arsenic could lead to different toxicity and curative effect. This study aims to establish a method to determine arsenic species in red blood cells (RBCs), clarify the distribution characteristics of arsenic species in RBCs. METHODS: Steady state blood samples were collected from 97 APL patients. H2O2 and HClO4 were used to release the hemoglobin bounding arsenic and precipitate protein. Arsenite (iAsIII), arsenate (iAsV), monomethylarsonic acid (MMAV) and dimethylarsinic acid (DMAV) in plasma and RBCs were detected by HPLC-HG-AFS. Free and bound arsenic species in RBCs were separated by 30 kDa molecular mass cutoff filters and determined to evaluate hemoglobin binding capacity of different arsenic species. RESULTS: The method was validated with accuracy ranged from 84.75% to 104.13%. Arsenic species in RBCs followed the trend iAs > MMA > DMA (p < 0.01), while the concentration of DMA was significantly higher than iAs and MMA in plasma (p < 0.01). The correlation between iAs concentration in plasma and corresponding RBCs arsenic level was weak. And the concentrations of DMA and MMA in plasma were moderately positive correlated with those in RBCs. Hemoglobin-binding ratios of iAs, MMA and DMA were all over 70 %. CONCLUSIONS: In this study, we provided a reliable method to determine arsenic species in RBCs of APL patients treated with ATO by HPLC-HG-AFS. It was confirmed that the concentration of DMA is the highest in plasma, while MMA is the most predominant methylated arsenic in RBCs. High affinity of MMA with human Hb was responsible for the accumulation of arsenic in RBCs of APL patients.

Characteristics and clinical influence factors of arsenic species in plasma and their role of arsenic species as predictors for clinical efficacy in acute promyelocytic leukemia (APL) patients treated with arsenic trioxide.

Background: Arsenic trioxide (ATO) is successfully applied to treat acute promyelocytic leukemia (APL). Arsenic species levels in blood are critical to reveal metabolic mechanism and relationship between arsenic species and clinical response. Characteristics and influence factors of arsenic species in APL patients have not been studied.Methods: 305 plasma samples from APL patients treated with ATO were analyzed using HPLC-HG-AFS. Trough concentration (Ctrough), distribution, methylation levels of arsenic species were evaluated. The influence factors on arsenic species levels of plasma and association between arsenic concentrations and clinical efficacy were explored.Results: Ctrough of arsenic in effective treatment groups provide basis for defining the target range of arsenic plasma concentrations in APL patients treated with ATO. Distribution trends: DMAV > AsIII, MMAV> AsV (p < 0.0001) for continuous slow-rate (CS) infusion and DMAV > MMAV > AsIII > AsV (p < 0.0001) for conventional infusion. Infusion methods and combined medication may affect arsenic metabolism. There was a weak correlation between ATO dose and plasma Ctrough of arsenic species. Ctrough of plasma arsenic species had predictive value for treatment efficacy.Conclusion: Arsenic concentration monitoring in APL patients treated with ATO is required. These findings are critical to optimize treatment outcomes of ATO therapy.

Characteristics of arsenic species in cerebrospinal fluid (CSF) of acute promyelocytic leukaemia (APL) patients treated with arsenic trioxide plus mannitol.

Arsenic speciation in cerebrospinal fluid (CSF) is critical for treatment/prevention of central nervous system (CNS) relapse in acute promyelocytic leukaemia (APL) patients treated with arsenic trioxide (ATO). Previous study showed low total arsenic level in CSF of APL patients. Mannitol infusion was applied to improve blood-brain barrier (BBB) permeability for arsenic. Arsenite (AsIII ), monomethylarsonic acid (MMAV ), dimethylarsinic acid (DMAV ), and arsenate (AsV ) in CSF and plasma were analysed by high performance liquid chromatography-hydride generation-atomic fluorescence spectrometry (HPLC-HG-AFS). The profile and concentration of arsenic species in CSF from APL patients administered ATO alone and in combination with mannitol were compared. The overall distribution trend of arsenic species in CSF was AsIII , DMAV > MMAV > AsV . Arsenicals accumulated in CSF with administration frequency. The permeability of BBB for AsIII was higher than that for MMAV and DMAV . Arsenic concentration in CSF was much lower than that in plasma. There were significantly higher arsenic species concentrations in CSF of APL patients treated with mannitol than that without mannitol. Mannitol infusion significantly increased AsIII penetration into CSF, which was beneficial to optimize efficacy in APL patients with CNS relapse.