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All- trans retinoic acid (ATRA) plus arsenic trioxide was found to be noninferior to ATRA plus chemotherapy, and less toxic, in the treatment of acute promyelocytic leukemia. This is an early example of a curative therapy for acute leukemia without chemotherapy. Acute promyelocytic leukemia (APL) has become a highly curable disease with contemporary treatment, which consists of all- trans retinoic acid (ATRA) and anthracycline-based chemotherapy. 1 , 2 As reported in several large multicenter trials, this combination results in overall remission rates of up to 95% and cure rates now exceeding 80%. 3 – 11 Thus, the combination of ATRA and chemotherapy is currently considered the standard of care for newly diagnosed APL. 12 Arsenic trioxide is also highly effective in the treatment of APL. Early studies conducted in China and the United States showed that this agent can induce sustained molecular remission when used as . . .

Acute promyelocytic leukaemia is a chemotherapy-sensitive subgroup of acute myeloid leukaemia characterised by the presence of the PML–RARA fusion transcript. The present standard of care, chemotherapy and all-trans retinoic acid (ATRA), results in a high proportion of patients being cured. In this study, we compare a chemotherapy-free ATRA and arsenic trioxide treatment regimen with the standard chemotherapy-based regimen (ATRA and idarubicin) in both high-risk and low-risk patients with acute promyelocytic leukaemia. In the randomised, controlled, multicentre, AML17 trial, eligible patients (aged ≥16 years) with acute promyelocytic leukaemia, confirmed by the presence of the PML–RARA transcript and without significant cardiac or pulmonary comorbidities or active malignancy, and who were not pregnant or breastfeeding, were enrolled from 81 UK hospitals and randomised 1:1 to receive treatment with ATRA and arsenic trioxide or ATRA and idarubicin. ATRA was given to participants in both groups in a daily divided oral dose of 45 mg/m2 until remission, or until day 60, and then in a 2 weeks on–2 weeks off schedule. In the ATRA and idarubicin group, idarubicin was given intravenously at 12 mg/m2 on days 2, 4, 6, and 8 of course 1, and then at 5 mg/m2 on days 1–4 of course 2; mitoxantrone at 10 mg/m2 on days 1–4 of course 3, and idarubicin at 12 mg/m2 on day 1 of the final (fourth) course. In the ATRA and arsenic trioxide group, arsenic trioxide was given intravenously at 0·3 mg/kg on days 1–5 of each course, and at 0·25 mg/kg twice weekly in weeks 2–8 of course 1 and weeks 2–4 of courses 2–5. High-risk patients (those presenting with a white blood cell count >10 × 109 cells per L) could receive an initial dose of the immunoconjugate gemtuzumab ozogamicin (6 mg/m2 intravenously). Neither maintenance treatment nor CNS prophylaxis was given to patients in either group. All patients were monitored by real-time quantitative PCR. Allocation was by central computer minimisation, stratified by age, performance status, and de-novo versus secondary disease. The primary endpoint was quality of life on the European Organisation for Research and Treatment of Cancer (EORTC) QLQ-C30 global health status. All analyses are by intention to treat. This trial is registered with the ISRCTN registry, number ISRCTN55675535. Between May 8, 2009, and Oct 3, 2013, 235 patients were enrolled and randomly assigned to ATRA and idarubicin (n=119) or ATRA and arsenic trioxide (n=116). Participants had a median age of 47 years (range 16–77; IQR 33–58) and included 57 high-risk patients. Quality of life did not differ significantly between the treatment groups (EORTC QLQ-C30 global functioning effect size 2·17 [95% CI −2·79 to 7·12; p=0·39]). Overall, 57 patients in the ATRA and idarubicin group and 40 patients in the ATRA and arsenic trioxide group reported grade 3–4 toxicities. After course 1 of treatment, grade 3–4 alopecia was reported in 23 (23%) of 98 patients in the ATRA and idarubicin group versus 5 (5%) of 95 in the ATRA and arsenic trioxide group, raised liver alanine transaminase in 11 (10%) of 108 versus 27 (25%) of 109, oral toxicity in 22 (19%) of 115 versus one (1%) of 109. After course 2 of treatment, grade 3–4 alopecia was reported in 25 (28%) of 89 patients in the ATRA and idarubicin group versus 2 (3%) of 77 in the ATRA and arsenic trioxide group; no other toxicities reached the 10% level. Patients in the ATRA and arsenic trioxide group had significantly less requirement for most aspects of supportive care than did those in the ATRA and idarubicin group. ATRA and arsenic trioxide is a feasible treatment in low-risk and high-risk patients with acute promyelocytic leukaemia, with a high cure rate and less relapse than, and survival not different to, ATRA and idarubicin, with a low incidence of liver toxicity. However, no improvement in quality of life was seen. Cancer Research UK.

The APL0406 study showed that arsenic trioxide (ATO) and all -trans retinoic acid (ATRA) are not inferior to standard ATRA and chemotherapy (CHT) in newly diagnosed, low–intermediaterisk acute promyelocytic leukaemia (APL). We analysed the kinetics of promyelocytic leukaemia–retinoic acid receptor-α (PML–RARα) transcripts by real-time quantitative PCR (RQ-PCR) in bone marrow samples from 184 patients and assessed the prognostic impact of fms-related tyrosine kinase 3 –internal tandem duplication ( FLT3 –ITD) in 159 patients enrolled in this trial in Italy. After induction therapy, the reduction of PML–RARα transcripts was significantly greater in patients receiving ATRA-CHT as compared with those treated with ATRA–ATO (3.4 vs 2.9 logs; P =0.0182). Conversely, at the end of consolidation, a greater log reduction of PML–RARα transcripts was detected in the ATRA–ATO as compared with the ATRA–CHT group (6.3 vs 5.3 logs; P =0.0024). FLT3 –ITD mutations had no significant impact on either event-free survival (EFS) or cumulative incidence of relapse in patients receiving ATRA–ATO, whereas a trend for inferior EFS was observed in FLT3 –ITD-positive patients receiving ATRA-CHT. Our study shows at the molecular level that ATRA–ATO exerts at least equal and probably superior antileukaemic efficacy compared with ATRA–CHT in low–intermediaterisk APL. The data also suggest that ATRA–ATO may abrogate the negative prognostic impact of FLT3 –ITD.

Worldwide, more than 200 million people are estimated to be exposed to unsafe levels of arsenic. Chronic exposure to unsafe levels of groundwater arsenic is responsible for multiple human disorders, including dermal, cardiovascular, neurological, pulmonary, renal, and metabolic conditions. Consumption of rice and seafood (where high levels of arsenic are accumulated) is also responsible for human exposure to arsenic. The toxicity of arsenic compounds varies greatly and may depend on their chemical form, solubility, and concentration. Surprisingly, synthetic organoarsenicals are extremely toxic molecules which created interest in their development as chemical warfare agents (CWAs) during World War I (WWI). Among these CWAs, adamsite, Clark I, Clark II, and lewisite are of critical importance, as stockpiles of these agents still exist worldwide. In addition, unused WWII weaponized arsenicals discarded in water bodies or buried in many parts of the world continue to pose a serious threat to the environment and human health. Metabolic inhibition, oxidative stress, genotoxicity, and epigenetic alterations including micro-RNA-dependent regulation are some of the underlying mechanisms of arsenic toxicity. Mechanistic understanding of the toxicity of organoarsenicals is also critical for the development of effective therapeutic interventions. This review provides comprehensive details and a critical assessment of recently published data on various chemical forms of arsenic, their exposure, and implications on human and environmental health.

Arsenicals are one of the oldest treatments for a variety of human disorders. Although infamous for its toxicity, arsenic is paradoxically a therapeutic agent that has been used since ancient times for the treatment of multiple diseases. The use of most arsenic-based drugs was abandoned with the discovery of antibiotics in the 1940s, but a few remained in use such as those for the treatment of trypanosomiasis. In the 1970s, arsenic trioxide, the active ingredient in a traditional Chinese medicine, was shown to produce dramatic remission of acute promyelocytic leukemia similar to the effect of all-trans retinoic acid. Since then, there has been a renewed interest in the clinical use of arsenicals. Here the ancient and modern medicinal uses of inorganic and organic arsenicals are reviewed. Included are antimicrobial, antiviral, antiparasitic and anticancer applications. In the face of increasing antibiotic resistance and the emergence of deadly pathogens such as the severe acute respiratory syndrome coronavirus 2, we propose revisiting arsenicals with proven efficacy to combat emerging pathogens. Current advances in science and technology can be employed to design newer arsenical drugs with high therapeutic index. These novel arsenicals can be used in combination with existing drugs or serve as valuable alternatives in the fight against cancer and emerging pathogens. The discovery of the pentavalent arsenic-containing antibiotic arsinothricin, which is effective against multidrug-resistant pathogens, illustrates the future potential of this new class of organoarsenical antibiotics.

The Traditional Chinese Medicine, arsenic trioxide (ATO, As O ) could inhibit growth and induce apoptosis in a variety of solid tumor cells, but it is severely limited in the treatment of glioma due to its poor BBB penetration and nonspecifcity distribution in vivo. The objective of this study was encapsulating ATO in the modified PAMAM den-drimers to solve the problem that the poor antitumor effect of ATO to glioma, which provide a novel angle for the study of glioma treatment. The targeting drug carrier (RGDyC-mPEG-PAMAM) was synthesized based on Arg-Gly-Asp (RGDyC) and αvβ3 integrin targeting ligand, and conjugated to PEGylated fifth generation polyamidoamine dendrimer (mPEG-PAMAM). It was characterized by nuclear magnetic resonance, fourier transform infrared spectra, Nano-particle size-zeta potential analyzer,etc. The in vitro release characteristics were studied by dialysis bag method. MTT assay was used to investigate the cytotoxicity of carriers and the antitumor effect of ATO formulation. In vitro blood-brain barrier (BBB) and C6 cell co-culture models were established to investigate the inhibitory effect of different ATO formulation after transporting across BBB. Pharmacokinetic and antitumor efficacy studies were investigated in an orthotopic murine model of C6 glioma. The prepared RGDyC-mPEG-PAMAM was characterized for spherical dendrites, comparable size (21.60±6.81 nm), and zeta potential (5.36±0.22 mV). In vitro release showed that more ATO was released from RGDyC-mPEG-PAMAM/ATO (79.5%) at pH 5.5 than that of pH 7.4, during 48 hours. The cytotoxicity of PEG-modified carriers was lower than that of the naked PAMAM on both human brain microvascular endothelial cells and C6 cells. In in vitro BBB model, modification of RGDyC heightened the cytotoxicity of ATO loaded on PAMAM, due to an increased uptake by C6 cells. The results of cell cycle and apoptosis analysis revealed that RGDyC-mPEG-PAMAM/ATO arrested the cell cycle in G2-M and exhibited threefold increase in percentage of apoptosis to that in the PEG-PAMAM/ATO group. Compared with ATO-sol group, both RGDyC-mPEG-PAMAM/ATO and mPEG-PAMAM/ATO groups prolonged the half-life time, increased area under the curve, and improved antitumor effect, significantly. While the tumor volume inhibitory of RGDyC-mPEG-PAMAM/ATO was 61.46±12.26%, it was approximately fourfold higher than the ATO-sol group, and twofold to the mPEG-PAMAM/ATO group. In this report, RGDyC-mPEG-PAMAM could enhance the antitumor of ATO to glioma, it provides a desirable strategy for targeted therapy of glioma.

Both all-trans retinoic acid (ATRA) and arsenic trioxide (As 2 O 3 ) have proven to be very effective in obtaining high clinical complete remission (CR) rates in acute promyelocytic leukemia (APL), but they had not been used jointly in an integrated treatment protocol for remission induction or maintenance among newly diagnosed APL patients. In this study, 61 newly diagnosed APL subjects were randomized into three treatment groups, namely by ATRA, As 2 O 3 , and the combination of the two drugs. CR was determined by hematological analysis, tumor burden was examined with real-time quantitative RT-PCR of the PML-RAR α (promyelocytic leukemia - retinoic acid receptor α) fusion transcripts, and side effects were evaluated by means of clinical examinations. Mechanisms possibly involved were also investigated with cellular and molecular biology methods. Although CR rates in three groups were all high (≥90%), the time to achieve CR differed significantly, with that of the combination group being the shortest one. Earlier recovery of platelet count was also found in this group. The disease burden as reflected by fold change of PML-RARα transcripts at CR decreased more significantly in combined therapy as compared with ATRA or As 2 O 3 mono-therapy ( P < 0.01). This difference persisted after consolidation ( P < 0.05). Importantly, all 20 cases in the combination group remained in CR whereas 7 of 37 cases treated with mono-therapy relapsed ( P < 0.05) after a follow-up of 8–30 months (median: 18 months). Synergism of ATRA and As 2 O 3 on apoptosis and degradation of PML-RARα oncoprotein might provide a plausible explanation for superior efficacy of combinative therapy in clinic. In conclusion, the ATRA/As 2 O 3 combination for remission/maintenance therapy of APL brings much better results than either of the two drugs used alone in terms of the quality of CR and the status of the disease-free survival.

Arsenic (As) is widely used in the modern industry, especially in the production of pesticides, herbicides, wood preservatives, and semiconductors. The sources of As such as contaminated water, air, soil, but also food, can cause serious human diseases. The complex mechanism of As toxicity in the human body is associated with the generation of free radicals and the induction of oxidative damage in the cell. One effective strategy in reducing the toxic effects of As is the usage of chelating agents, which provide the formation of inert chelator–metal complexes with their further excretion from the body. This review discusses different aspects of the use of metal chelators, alone or in combination, in the treatment of As poisoning. Consideration is given to the therapeutic effect of thiol chelators such as meso-2,3-dimercaptosuccinic acid, sodium 2,3-dimercapto-1-propanesulfonate, 2,3-dimercaptopropanol, penicillamine, ethylenediaminetetraacetic acid, and other recent agents against As toxicity. The review also considers the possible role of flavonoids, trace elements, and herbal drugs as promising natural chelating and detoxifying agents.

Arsenic is a worldwide environmental pollutant and a human carcinogen. It is well recognized that the toxicity of arsenicals largely depends on the oxidoreduction states (trivalent or pentavalent) and methylation levels (monomethyl, dimethyl, and trimethyl) that are present during the process of metabolism in mammals. However, presently, the specifics of the metabolic pathway of inorganic arsenicals have yet to be confirmed. In mammals, there are two possible mechanisms that have been proposed for the metabolic pathway of inorganic arsenicals, oxidative methylation, and glutathione conjugation. Oxidative methylation, which was originally proposed in fungi, is based on findings that arsenite (iAs III ) is sequentially converted to monomethylarsonic acid (MMA V ) and dimethylarsinic acid (DMA V ) in both humans and in laboratory animals such as mice and rats. However, recent in vitro observations have demonstrated that arsenic is only methylated in the presence of glutathione (GSH) or other thiol compounds, which strongly suggests that arsenic is methylated in trivalent forms. The glutathione conjugation mechanism is supported by findings that have shown that most intracellular arsenicals are trivalent and excreted from cells as GSH conjugates. Since non-conjugated trivalent arsenicals are highly reactive with thiol compounds and are easily converted to less toxic corresponding pentavalent arsenicals, the arsenic–glutathione conjugate stability may be the most important factor for determining the toxicity of arsenicals. In addition, “being a non-anionic form” also appears to be a determinant of the toxicity of oxo-arsenicals or thioarsenicals. The present review discusses both the metabolism of arsenic and the toxicity of arsenic metabolites.

Standard treatment for GBM is radiation (RT) and temozolomide (TMZ). Arsenic trioxide (ATO) is synergistic with RT based on several mechanisms of action previously identified, however not tested herein. The MTD of ATO, RT and TMZ was determined in a Phase I trial. We now present the combined Phase I/II data. Patients with newly diagnosed malignant gliomas were eligible for treatment. Patients were treated with RT (60 GY), TMZ (75 mg/m 2 daily × 42 days) and ATO 0.20 mg/kg daily in week 1 then twice a week ×5 weeks, after completing RT they were treated with TMZ 5/28 for up to 12 months. MRIs were performed every 8 weeks. A total of 42 patients were enrolled in both the Phase I and II trials for this study treatment. Of the 42 enrolled patients (24 M and 18 W) the median age was 54 (24–80) and median KPS 90 (60–100). 28 patients had a GBM and 14 had anaplastic glioma (AG). All patients completed RT/TMZ/ATO and went on to maintenance TMZ. Median number of post RT cycles of TMZ was 4 (0–12). Median PFS was 7 m for GBM and 75 m for AG and median OS was 17 m for GBM and NR for AG. Best response was CR in 2, SD in 28, PR in 5 and PD in 7. There were no unexpected adverse events. Grade 3 toxicities likely attributable to ATO included prolonged Qtc (n = 1), elevated liver enzymes (n = 2 for ALT/n = 1 for AST) and elevated bilirubin (n = 1). Adding ATO to RT and TMZ is feasible with no increased side effects. The addition of arsenic did not improve overall survival in the GBM patients as compared to historic data. MGMT status was analyzed in 20 of the 42 patients where tissue was available for retrieval and MGMT testing.