Combination Of Arsenic Trioxide Research Articles

Improved Outcomes of All-Trans-Retinoic Acid and Arsenic Trioxide Plus Idarubicin As a Frontline Treatment in Adult Patients with Acute Promyelocytic Leukemia

Objective To analyze the outcomes of all-trans-retinoic acid (ATRA) and IV arsenic trioxide (ATO) plus idarubicin (IDA) as a frontline induction therapy in 118 acute promyelocytic leukemia (APL) patients with high risk (HR) and standard risk (SR) from January 2008 to December 2017. Methods The medical records of 118 APL patients (HR, n=45; SR, n=73) who received the frontline triple combination regimen at Henan Provincial People's Hospital and Tongji Hospital were retrospectively reviewed. Consolidation therapy comprised 6 cycles of ATO and ATRA plus IDA, and IDA was administered in 1~4 cycles of consolidation therapy based on the comparable clinical efficacy compared with 6 cycles and fewer side effects to myocardium without subsequent maintenance therapy. Results Of 118 patients, there were 3 (2.5%) early deaths and 115 (97.5%) hematologic complete remissions (hCR), and 102 (88.7%) of 115 patients achieved molecular complete remissions (mCR) following induction therapy, and all patients were PCR-negative for PML-RARa after the first cycle of consolidation therapy. The 5-year overall survival (OS) and event-free survival (EFS) were 93.0±2.9% and 92.4±3.0%, respectively. Early death, hCR, mCR and toxicities were comparable between the HR and SR groups. The cumulative incidence of relapse (CIR) in the HR group was 4.7% (n=2), and the CIR in the SR group was 0. The OS and EFS of the SR and HR groups were comparable (92.3±4.5 vs. 92.8±4.0%, X2=0.263, P=0.608; 92.3±4.5 vs. 91.1±4.2%, X2=0.917, P=0.338). The total dosage of IDA was approximately 181~258 mg, and no patient experienced cardiotoxicity. OS and EFS were not influenced by fms-related tyrosine kinase 3 internal tandem duplication (FLT3-ITD) mutation status (P=0.405, 0.528, respectively). Conclusion The triple combination of ATRA and ATO plus IDA as both an induction and consolidation therapy for the HR and SR groups attained excellent outcomes, and this regimen was effective, safe and easy, without maintenance therapy. The triple combination treatment might be a preferred frontline therapy for APL patients, especially for HR patients or patients with the APL FLT3-ITD mutation. Disclosures No relevant conflicts of interest to declare.

Arsenic Trioxide Synergistically Enhances the Antileukemia Activity of Bcl-2 Inhibitor ABT-199 in Acute Myeloid Leukemia

Background Acute myeloid leukaemia (AML) is a malignancy derived from haematopoietic stem cells in which maturation and apoptosis are blocked and proliferation is uncontrolled during differentiation. With the optimization of chemotherapy regimens, the emergence of new drugs and the development of haematopoietic stem cell transplantation technology, the complete remission (CR) rate and long-term survival of AML patients have significantly improved, but 20-40% of patients still have difficulty achieving a CR. Furthermore, approximately 60% of patients eventually relapse after a CR. Patients who are unable to obtain a CR and who relapse after remission are more likely to develop refractory AML. For patients with refractory/relapsed AML, there is no standard rescue therapy, and general chemotherapy drugs have limited efficacy. It is of great significance to explore new salvage treatment options. Venetoclax (ABT-199) is an effective oral inhibitor of Bcl-2. ABT-199 has been used to treat various in vitro and in vivo tumour models, including AML models, and these experiments have shown its effectiveness as a single agent. However, its efficacy is very limited in refractory/relapsed AML, Mcl-1 play important roles in ABT-199 resistance. As an ancient pro-apoptotic drug, arsenic trioxide (ATO) has been shown to induce apoptosis in vivo and in vitro. ATO can downregulate the expression of Mcl-1, thereby inducing apoptosis. objective To explore not only the synergistic pro-apoptotic effects of the Bcl-2 inhibitor ABT-199 and ATO on AML cell lines and AML primary cells, but also the clinical effects on refractory/relapsing AML patients. Methods 1. Bcl-2 and Mcl-1 mRNA and protein levels in AML cell lines (MOLM13, MV4-11, THP-1, OCI-AML3, U937) were detected by real-time PCR and Western blot, respectively; 2.Apoptosis rates of AML cell lines after treatment with different concentrations of ABT-199 or ATO alone or in combination were measured by flow cytometry; 3. The transcriptomes of THP-1 and OCI-AML3 cells before and after treatment with ABT-199 or ATO alone or in combination were analysed; 4. Western blot, co-immunoprecipitation, cell cycle assay ABT-199, ATO effect on oci-AML3 cells; 5. ABT-199 combined with ATO in the treatment of patients with relapsed and refractory AML, the specific program is: ABT-199 100mg d1, 200mg d2, 400mg d3-28, oral 30 minutes after breakfast, ATO 6mg/m2, d1-28, daily intravenous infusion for 6 hours, review the effect of bone marrow aspiration on the 28th day. Results 1.MOLM13, MV4-11, THP-1, OCI-AML3 and U937 cells expressed both Bcl-2 and Mcl-1. The sensitivity of AML cell lines to ABT-199 was positively correlated with the Bcl-2 protein expression level; 2.In AML cell lines whether ABT-sensitive or ABT-resistant and primary AML cells, ABT-199 and ATO synergistically promoted apoptosis in a time- and concentration-dependent manner; 3. ABT-199 up-regulated the expression of Mcl-1 in ABT-resistant OCI-AML3 cells, ATO down-regulated the expression of p-AKT, p-GSK3β, and Mcl-1, and the expression of Mcl-1 decreased after the combination of the two drugs. Bim and Mcl-1 protein binding decreased after treatment OCI-AML3 cells with the combination of the two drugs for 24h; 4. ATO promotes DNA damage, and the effect is further enhanced when combinated with ABT-199; 5. A total of 7 patients with relapse were treated with ABT-ATO combined regimen. Four of the 7 patients had multiple relapses and 3 patients had short-term recurrence after remission, with an average age of 49 years. On the 28th day, the bone marrow was reviewed. Two of them achieved CRi, one case with Leukemia-free state (MLFS), two cases with PR, one case with SD, and one case with PD. Conclusion We demenstrated ATO could reverse AML resistance to ABT-199 and the synergistic effects of the combination of ATO and ABT-199, which may provide a new and probably more effective treatment strategy for refractory/relapsed AML . Key Words Bcl-2 inhibitor; ABT-199; arsenic trioxide; Mcl-1; AKT; apoptosis Disclosures No relevant conflicts of interest to declare.

Improved Outcomes of All-trans-retinoic Acid and Arsenic Trioxide Plus Idarubicin as a Frontline Treatment in Adult Patients With Acute Promyelocytic Leukemia

IntroductionThe purpose of this study was to explore the outcomes of all-trans-retinoic acid (ATRA) and arsenic trioxide (ATO) plus idarubicin (IDA) as a frontline treatment in adult patients with acute promyelocytic leukemia (APL). Patients and MethodsWe analyzed the outcomes of ATRA and intravenous ATO plus IDA as a frontline induction therapy in 118 patients with APL with high-risk (HR) and standard-risk (SR) disease from January 2008 to December 2017. The medical records of 118 patients with APL (HR, n = 45; SR, n = 73) who received the frontline triple combination regimen at Henan Provincial People’s Hospital and Tongji Hospital were retrospectively reviewed. Consolidation therapy comprised 6 cycles of ATO and ATRA plus IDA, and IDA was administered in 1 to 4 cycles of consolidation therapy based on the comparable clinical efficacy compared with 6 cycles and fewer side effects to myocardium without subsequent maintenance therapy. ResultsOf 118 patients, there were 3 (2.5%) early deaths and 115 (97.5%) hematologic complete remissions; 102 (88.7%) of 115 patients achieved molecular complete remission following induction therapy, and all patients were polymerase chain reaction-negative for promyelocytic leukemia-retinoic acid receptor alpha after the first cycle of consolidation therapy. The 5-year overall survival (OS) and event-free survival (EFS) were 93.0% ± 2.9% and 92.4% ± 3.0%, respectively. Early death, hematologic complete remissions, molecular complete remissions, and toxicities were comparable between the HR and SR groups. The cumulative incidence of relapse in the HR group was 4.7% (n = 2), and the cumulative incidence of relapse in the SR group was 0. The OS and EFS of the SR and HR groups were comparable (92.3% ± 4.5% vs. 92.8% ± 4.0%; X2 = 0.263; P = .608; 92.3% ± 4.5% vs. 91.1% ± 4.2%, X2 = 0.917; P = .338). The total dosage of IDA was approximately 181 to 258 mg, and no patient experienced cardiotoxicity. OS and EFS were not influenced by fms-related tyrosine kinase 3 internal tandem duplication mutation status (P = .405 and P = .528, respectively). ConclusionThe triple combination of ATRA and ATO plus IDA as both an induction and consolidation therapy for the HR and SR groups attained excellent outcomes, and this regimen was effective, safe, and easy, without maintenance therapy. The triple combination treatment might be a preferred frontline therapy for patients with APL, especially for those with HR or the APL fms-related tyrosine kinase 3 internal tandem duplication mutation.

A chirality-dependent action of vitamin C in suppressing Kirsten rat sarcoma mutant tumor growth by the oxidative combination: Rationale for cancer therapeutics.

Kirsten rat sarcoma (KRAS) mutant cancers, which constitute the vast majority of pancreatic tumors, are characterized by their resistance to established therapies and high mortality rates. Here, we developed a novel and extremely effective combinational therapeutic approach to target KRAS mutant tumors through the generation of a cytotoxic oxidative stress. At high concentrations, vitamin C (VC) is known to provoke oxidative stress and selectively kill KRAS mutant cancer cells, although its effects are limited when it is given as monotherapy. We found that the combination of VC and the oxidizing drug arsenic trioxide (ATO) is an effective therapeutic treatment modality. Remarkably, its efficiency is dependent on chirality of VC as its enantiomer d-optical isomer of VC (d-VC) is significantly more potent than the natural l-optical isomer of VC. Thus, our results demonstrate that the oxidizing combination of ATO and d-VC is a promising approach for the treatment of KRAS mutant human cancers.

Inhibition of PI3K pathway using BKM120 intensified the chemo-sensitivity of breast cancer cells to arsenic trioxide (ATO)

Although conventional therapeutic approaches have brought remarkable advantages for the treatment of breast cancer (BC), drug-resistance still remains as a leading cause of tumor recurrence in this malignancy. In the present study, we designed experiments to evaluate the therapeutic value of PI3K inhibition in combination with Arsenic trioxide (ATO) in MCF-7 cells. The results of our study manifested that BKM120 sensitized MCF-7 cells to the lower concentrations of ATO. The significant anti-cancer effect of PI3K inhibition became even more evident when we found that BKM120, either as a single agent or in combination with ATO, reduced clonogenic ability of anoikis-resistant stem-like MCF-7 cells. Our findings also showed that BKM120 augmented ATO-induced anti-proliferative effects through inducing G1 arrest and reducing the incorporation of BrdU into the synthesized DNA of drugs-treated cells, which was coupled with c-Myc-mediated suppression of hTERT expression. Moreover, we found that in the presence of PI3K inhibitor, ATO is able to more profoundly induce apoptosis in MCF-7 cells, as revealed by the increment in the percentage of haplodiploid sub-G1 cells and the externalization of phosphatidylserine. Real-time PCR analysis also revealed that probably down-regulation of survivin coupled with up-regulation of forkhead family transcription factors is responsible for the enhancive effect of drugs in this cell line. Conclusively, this study shed lights on the effect of PI3K inhibition in chemo-sensitivity of MCF-7 cells, disclosing that combination of BKM120 and ATO could be a promising therapeutic approach in BC.

Synergy between arsenic trioxide and JQ1 on autophagy in pancreatic cancer.

Pancreatic cancer is a deadliest type of malignancy and lacks effective intervention. We here report a potential strategy for treatment of this malignancy by the combination of arsenic trioxide (ATO) and BET bromodomain inhibitor JQ1. These two agents synergistically modulate multistages of autophagy and thus induce apoptosis effectively in pancreatic cancer cells. Our genomic and biochemical data have demonstrated that crosstalks between ER stress and autophagy play crucial roles during ATO-induced apoptosis, in which NRF2 may stand at the crossroad between cell death and survival. This has been further strengthened by our finding that NRF2 depletion renders insensitive cells into sensitive ones in regard to ATO treatment-caused cell death. The knockdown of NRF2 and the addition of JQ1 result in similar molecular/cellular effects in promoting effective ATO-induced apoptosis in cells that are insensitive to ATO treatment alone. Thus, the combination of ATO and JQ1 may represent a new treatment strategy for pancreatic cancer.

Targeting Glutamine Metabolism and Redox State for Leukemia Therapy.

Acute myeloid leukemia (AML) is a hematologic malignancy characterized by the accumulation of immature myeloid precursor cells. AML is poorly responsive to conventional chemotherapy and a diagnosis of AML is usually fatal. More effective and less toxic forms of therapy are desperately needed. AML cells are known to be highly dependent on the amino acid glutamine for their survival. These studies were directed at determining the effects of glutaminase inhibition on metabolism in AML and identifying general weaknesses that can be exploited therapeutically. AML cancer cell lines, primary AML cells, and mouse models of AML and acute lymphoblastic leukemia (ALL) were utilized. We show that blocking glutamine metabolism through the use of a glutaminase inhibitor (CB-839) significantly impairs antioxidant glutathione production in multiple types of AML, resulting in accretion of mitochondrial reactive oxygen species (mitoROS) and apoptotic cell death. Moreover, glutaminase inhibition makes AML cells susceptible to adjuvant drugs that further perturb mitochondrial redox state, such as arsenic trioxide (ATO) and homoharringtonine (HHT). Indeed, the combination of ATO or HHT with CB-839 exacerbates mitoROS and apoptosis, and leads to more complete cell death in AML cell lines, primary AML patient samples, and in vivo using mouse models of AML. In addition, these redox-targeted combination therapies are effective in eradicating ALL cells in vitro and in vivo. Targeting glutamine metabolism in combination with drugs that perturb mitochondrial redox state represents an effective and potentially widely applicable therapeutic strategy for treating multiple types of leukemia.

Retinoic acid and arsenic trioxide induce lasting differentiation and demethylation of target genes in APL cells

Acute promyelocytic leukemia (APL) is characterized by arrested differentiation of promyelocytes. Patients treated with all-trans retinoic acid (ATRA) alone experience relapse, while patients treated with ATRA and arsenic trioxide (ATO) are often relapse-free. This suggests sustained changes have been elicited by the combination therapy. To understand the lasting effects of the combination therapy, we compared the effects of ATRA and ATO on NB4 and ATRA-resistant NB4-MR2 APL cells during treatment versus post treatment termination. After treatment termination, NB4 cells treated with ATRA or ATO reverted to non-differentiated cells, while combination-treated cells remained terminally differentiated. This effect was diminished in NB4-MR2 cells. This suggests combination treatment induced more permanent changes. Combination treatment induced higher expression of target genes (e.g., transglutaminase 2 and retinoic acid receptor beta), which in NB4 cells was sustained post treatment termination. To determine whether sustained epigenetic changes were responsible, we quantified the enrichment of histone modifications by chromatin immunoprecipitation, and CpG methylation by bisulfite-pyrosequencing. While ATRA and combination treatment induced similar histone acetylation enrichment, combination treatment induced greater demethylation of target genes, which was sustained. Therefore, sustained demethylation of target genes by ATRA and ATO combination treatment is associated with lasting differentiation and gene expression changes.

PB1692 G-CSF ACTIVATING P38 MAPK PATHWAY ENHANCES THE ANTI-LEUKEMIC ACTIVITY OF ARSENIC TRIOXIDE IN VITRO THROUGH UP-REGULATING AQP9 EXPRESSION

Background: Because of relatively lower chemotherapy-related side effects and better tolerance, granulocyte colony-stimulating factor (G-CSF) combining with other low dosage chemotherapeutics has been widely used in elderly acute myeloid leukemia (AML) patients in China. Unfortunately not all patients benefit from this regimen. Therefore, identifying novel treatment protocols with minimal toxicities and overcoming drug resistance remain the most challenging scenarios facing this population of patients. Arsenic trioxide (ATO) shows its effects in acute promyelocytic leukemia treatment and may show promising effects in other subtypes of acute myeloid leukemia. The aquaporin 9 (AQP9) expression on the leukemia membrane limits ATO transporting into the leukemia cells. Therefore, we hypothesize that the combination of ATO and specific factor which may regulate AQP9 expression would increase arsenic-induced cytotoxicity in AML. Aims: To evaluate the feasibility of combining G-CSF and arsenic trioxide in AML and to explore the mechanisms underlying the increased sensitivity of AML cells to ATO induced by G-CSF. Methods: Acute myeloid leukemia HL-60 and THP-1 cells were treated with G-CSF and/or ATO. AQP9 expression was suppressed by culturing these leukemia cells with phloretin. Cell viability, apoptosis and cell cycle distribution of each group were assessed by CCK-8 and flow cytometry respectively. Mechanistic studies were carried out by RT-qPCR and western blotting. Results: Compared with single-agent treatment in HL-60 and THP-1 cells, the combination of G-CSF and arsenic trioxide was associated with decreased cell proliferation and increased apoptosis as well as altered cell cycle distribution. Mechanistically, G-CSF treatment triggered up-regulation of AQP9, which was found to control arsenic transport and might determine ATO sensitivity. G-CSF also increased phosphorylation P38 expression. Furthermore, G-CSF induced AQP9 expression effects can be neutralized by phloretin. Summary/Conclusion: The pretreatment AML cells with G-CSF enhanced ATO anti-leukemic effect. This effect may relate with G-CSF-driven up-regulation of AQP9 expression and may be associated with the activation of P38 MAPK signaling pathway. Our findings suggest that synergistic effects of ATO and G-CSF may provide as a new therapeutic approach for elderly AML patients.

Combination of arsenic trioxide and cisplatin synergistically inhibits both hexokinase activity and viability of Ehrlich ascites carcinoma cells.

Hexokinase-2 is overexpressed in several carcinomas including breast cancer to sustain energy for rapidly dividing cells and associates with chemoresistance. However, the impact of chemo drugs (alone or in combination) on hexokinase activity and autophagic cell death is unclear. In this report, we used an in vivo murine adenocarcinoma model to validate the effects of As2 O3 and cisplatin on hexokinase activity and autophagic cancer cell death. We found that the two drugs inhibit hexokinase activity and induce autophagic marker, beclin 1 expression. Interestingly, combining As2 O3 with cisplatin synergistically enhanced these effects and alleviated oxidative stress often encountered in As2 O3 treatment. Altogether, our data provide direct evidence that inhibition of hexokinase activity and induction of autophagic cell death are mediating the antineoplastic effects of As2 O3 and cisplatin. Our findings raise the potential of combining As2 O3 with cisplatin as an approach to augment cisplatin-induced cell death and combat cisplatin chemoresistance in cancer.

Arsenic Trioxide Impacts Viral Latency and Delays Viral Rebound after Termination of ART in Chronically SIV-Infected Macaques.

The latent viral reservoir is the source of viral rebound after interruption of antiretroviral therapy (ART) and is the major obstacle in eradicating the latent human immunodeficiency virus‐1 (HIV‐1). In this study, arsenic class of mineral, arsenic trioxide, clinically approved for treating acute promyelocytic leukemia, is demonstrated to reactivate latent provirus in CD4+ T cells from HIV‐1 patients and Simian immunodeficiency virus (SIV)‐infected macaques, without significant systemic T cell activation and inflammatory responses. In a proof‐of‐concept study using chronically SIVmac239‐infected macaques, arsenic trioxide combined with ART delays viral rebound after ART termination, reduces the integrated SIV DNA copies in CD4+ T cells, and restores CD4+ T cells counts in vivo. Most importantly, half of arsenic trioxide‐treated macaques show no detectable viral rebound in the plasma for at least 80 days after ART discontinuation. Mechanistically, the study reveals that CD4 receptors and CCR5 co‐receptors of CD4+ T cells are significantly downregulated by arsenic trioxide treatment, which reduces susceptibility to infection after provirus reactivation. Furthermore, an increase in SIV‐specific immune responses after arsenic trioxide treatment may contribute to suppression of viral rebound. This work suggests that arsenic trioxide in combination with ART is a novel regimen in down‐sizing or even eradicating latent HIV‐1 reservoir.

Effect of combination of all-trans retinoic acid and arsenic trioxide on apoptosis of acute promyelocytic leukemia cells

To study the effect of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) combination treatment on apoptosis of acute promyelocytic leukemia cells (NB4), inflammation and prognosis. The effect of ATRA - ATO combination on the proliferation of NB4 was determined using MTT assay. Apoptosis of NB4 cells was assessed with TUNEL assay. The effect of ATRA-As2O3 combination on the expressions of IL-6 and TNF-α in NB4 cells was determined using ELISA kits, while its effect on the quality of life of 25 acute promyelocytic leukemia patients admitted to our hospital was scored, as an index of prognosis. The combination treatment with ATRA and ATO significantly inhibited the proliferation of NB4 cells and promoted their apoptosis, relative to the model group. In addition, the combination treatment reduced serum IL-6 and TNF-α levels in patients with acute promyelocytic leukemia, and improve their quality of life and survival. Combination treatment with ATRA and ATO significantly inhibits the proliferation of NB4 cells and promotes their apoptosis, and reduces inflammatory responses in patients with acute promyelocytic leukemia, while improving their quality of life and prognosis.

Antitumor efficacy of arsenic/interferon in preclinical models of chronic myeloid leukemia resistant to tyrosine kinase inhibitors.

Tyrosine kinase inhibitors (TKIs) are the standard treatment for chronic myeloid leukemia (CML). Despite their clinical success, TKIs are faced with challenges such as treatment resistance, which may be driven by kinase domain mutations, and frequent disease relapse upon the cessation of treatment. The combination of arsenic trioxide (ATO) and interferon-α (IFN) was previously demonstrated to inhibit proliferation and induce apoptosis in CML cell lines, prolong the survival of primary wild-type CML mice, and dramatically decrease the activity of leukemia-initiating cells (LICs). The ATO/IFN combination was tested in vitro on imatinib (IMN)-resistant K562-R and Ar230-R cells. 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate nick-end labeling assays were used to evaluate proliferation and apoptosis, respectively. The acridine orange assay was used to assess autophagy, and quantitative reverse transcription-polymerase chain reaction was used to assess the involvement of the hedgehog (Hh) pathway. In vivo, a retroviral transduction/transplantation T315I BCR-ABL CML mouse model was used to assay the effect of the treatment on survival, tumor burden (histopathology and blood counts), and LIC activity (secondary transplantation). In vitro, ATO/IFN synergized to inhibit proliferation and induce apoptosis of IMN-resistant cells with variant modes of resistance. Furthermore, the preclinical effects of ATO/IFN were associated with induction of autophagy along with inhibition of the Hh pathway. Most remarkably, ATO/IFN significantly prolonged the survival of primary T315I-CML mice and displayed a dramatic impairment of disease engraftment in secondary mice, which reflected decreased LIC activity. Collectively, the ATO/IFN strategy has been demonstrated to have the potential to lead to durable remissions in TKI-resistant CML preclinical models and to overcome various TKI-specific mechanisms of resistance.

Vulnerabilities in mIDH2 AML confer sensitivity to APL-like targeted combination therapy

Although targeted therapies have proven effective and even curative in human leukaemia, resistance often ensues. IDH enzymes are mutated in ~20% of human AML, with targeted therapies under clinical evaluation. We here characterize leukaemia evolution from mutant IDH2 (mIDH2)-dependence to independence identifying key targetable vulnerabilities of mIDH2 leukaemia that are retained during evolution and progression from early to late stages. Mechanistically, we find that mIDH2 leukaemia are metastable and vulnerable at two distinct levels. On the one hand, they are characterized by oxidative and genotoxic stress, in spite of increased 1-carbon metabolism and glutathione levels. On the other hand, mIDH2 leukaemia display inhibition of LSD1 and a resulting transcriptional signature of all-trans retinoic acid (ATRA) sensitization, in spite of a state of suppressed ATRA signalling due to increased levels of PIN1. We further identify GSH/ROS and PIN1/LSD1 as critical nodes for leukaemia maintenance and the combination of ATRA and arsenic trioxide (ATO) as a key therapeutic modality to target these vulnerabilities. Strikingly, we demonstrate that the combination of ATRA and ATO proves to be a powerfully synergistic and effective therapy in a number of mouse and human mIDH1/2 leukemic models. Thus, our findings pave the way towards the treatment of a sizable fraction of human AMLs through targeted APL-like combinatorial therapies.

Decitabine shows synergistic effects with arsenic trioxide against myelodysplastic syndrome cells via endoplasmic reticulum stress-related apoptosis

Most of the International Prognostic Scoring System (IPSS) high-risk patients with myelodysplastic syndrome partly responded to hypomethylating therapy even with transient remission, while arsenic trioxide (ATO) had partial effect in...

Pre-application of arsenic trioxide may potentiate cytotoxic effects of vinorelbine/docetaxel on neuroblastoma SK-N-SH cells

Background: Arsenic trioxide is effective in the treatment of acute promyelocytic leukemia and is currently in use in clinical trials for the treatment of solid tumor types. Given that arsenic trioxide is able to arrest neuroblastoma cell cycle in the G2/M phase, the present study is, to the best of our knowledge, the first to investigate whether the combination of arsenic trioxide with mitosis-phase-specific antineoplastic agents (vinorelbine or docetaxel) or non-mitosis-phase-specific antineoplastic agents (etoposide or cisplatin) exert synergistic effects in cytotoxicity on the human SK-N-SH neuroblastoma cell line.Methods: Neuroblastoma cells were either incubated with one of the four drugs individually, or preincubated with arsenic trioxide and then followed by another drug when cell cycle was arrested at the G2/M phase with the highest proportion.Results: The results of the present study revealed that arsenic trioxide potentiated the apoptotic rate of neuroblastoma cells induced by chemotherapeutic drugs. The present study further demonstrated that preincubation with arsenic trioxide followed by a mitosis-phase-specific antineoplastic agent result in a higher cytotoxicity effect compared with a non mitosis-phase-specific antineoplastic agent. Along with the enhanced cytotoxicity in combination group, the cell cycle distribution demonstrated a decreased proportion of G2/M phase in the combination group.Conclusion: The in vitro study revealed that the pre-application of arsenic trioxide followed by mitosis-phase-specific antineoplastic agents potentiate the cytotoxic effects on neuroblastoma cells, therefore arsenic trioxide may be a promising therapeutic option for treating neuroblastoma.

Arsenic Trioxide and (-)-Gossypol Synergistically Target Glioma Stem-Like Cells via Inhibition of Hedgehog and Notch Signaling.

Glioblastoma is one of the deadliest malignancies and is virtually incurable. Accumulating evidence indicates that a small population of cells with a stem-like phenotype is the major culprit of tumor recurrence. Enhanced DNA repair capacity and expression of stemness marker genes are the main characteristics of these cells. Elimination of this population might delay or prevent tumor recurrence following radiochemotherapy. The aim of this study was to analyze whether interference with the Hedgehog signaling (Hh) pathway or combined Hh/Notch blockade using small-molecule inhibitors can efficiently target these cancer stem cells and sensitize them to therapy. Using tumor sphere lines and primary patient-derived glioma cultures we demonstrate that the Hh pathway inhibitor GANT61 (GANT) and the arsenic trioxide (ATO)-mediated Hh/Notch inhibition are capable to synergistically induce cell death in combination with the natural anticancer agent (−)-Gossypol (Gos). Only ATO in combination with Gos also strongly decreased stemness marker expression and prevented sphere formation and recovery. These synergistic effects were associated with distinct proteomic changes indicating diminished DNA repair and markedly reduced stemness. Finally, using an organotypic brain slice transplantation model, we show that combined ATO/Gos treatment elicits strong growth inhibition or even complete elimination of tumors. Collectively, our data show for the first time that ATO and Gos, two drugs that can be used in the clinic, represent a promising targeted therapy approach for the synergistic elimination of glioma stem-like cells.

Synergistic anti-tumor effects of arsenic trioxide and blue LED irradiation on human osteosarcoma.

Arsenic trioxide (ATO) has been well recognized as an anti-tumor agent for various human cancers. Recently, the blue light emitting diodes (LEDs)-based therapy has also been demonstrated to be potential therapeutic strategies for several cancers. However, the combination effects of ATO and blue LED on tumor suppression are still unclear. In this study, we determined whether combination of ATO and blue LED irradiation at 470 nm in wavelength exhibited superior anti-tumor activity in human osteosarcoma (OS). We observed that combination treatments of ATO and blue LED much more significantly decreased the percentages of proliferative cells, and increased apoptotic rate compared with any single treatments in U-2 OS cells. Furthermore, we found suppression of cell migration and invasion were much more pronounced in ATO plus blue LED treated group than single treated groups. Moreover, reactive oxygen species (ROS) assay and immunostaining of γ-H2A.X and p53 indicated that the combined treatments resulted in further markedly increases in ROS accumulation, DNA damage and p53 activity. Taken together, our study demonstrated synergistical anti-tumor effects of combined treatments of ATO and blue LED on human OS cells, which were associated with an increased ROS accumulation, DNA damaged mediated p53 activation.

Very Long Term Follow-up Data of Pediatric Acute Promyelocytic Leukemia Treated with Upfront Arsenic-Trioxide Based Regimens

Combination of all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) is currently considered the standard of care in the management of acute promyelocytic leukemia (APL). While APL is considered a highly curable malignancy there is recognition that the outcome in pediatric patients is inferior to that reported in young adults. There have been concerns raised in the past on the potential long term side effects of the use of ATO, especially in a pediatric population. There is limited long term follow up data on the use of ATO in the pediatric population. At our center we have been using ATO based regimens to treat pediatric and adult patients with APL since 1998 and hence we undertook this retrospective analysis to evaluate the long term clinical outcomes and toxicity profile in the pediatric cohort.Data on all consecutive pediatric patients (age ≤18yrs) diagnosed with APL and treated in the Department of Haematology, Christian Medical College, Vellore, from January, 1998 to December, 2017 were included in this retrospective analysis. Of the total 73 patients with age ≤ 18yrs diagnosed during this period, 5 refused treatment and were discharged against medical advice. Treatment in the remaining 68 patients consisted of single agent ATO until 2015 (n=57), as reported previously by us (Mathews et al. Blood 2016). From 2015 combination of ATO, ATRA ± an anthracycline in induction and consolidation was administered in a risk adjusted manner (n=11). The median age was 2 years (range: 2-18) with equal gender distribution (50% each). Sixty two (91.2%) achieved complete hematologic remission (CR), 5 (7.4%) early deaths occurred from intracranial hemorrhage (n=3), neutropenic sepsis (n=1) and pulmonary thrombo-embolism (n=1), one patient did not achieve CR at the end of induction. The median time to CR was 45 days (range: 25- 62). Other acute ATO-related toxicities were low grade, transient and not associated with any mortality (transaminitis = 12 [17.6%]; ATRA like syndrome = 6 [8.8%]). With a median follow-up of 71 months, the 5 year OS and EFS of pediatric cohort (n=68) was 78.9±5.2% and 61.8±6.4% respectively (Fig 1). Among the 62 patients in CR, 21 (33.9%) relapsed at a median of 18 months (range: 5-126) from the initial diagnosis; 16 bone marrow, 3 bone marrow+CNS and 2 molecular relapses; an additional 2 patients died in remission (one viral encephalitis and another data not available). Nineteen out of 21 (90.5%) patients who relapsed received ATO based re-induction while 2 refused treatment and were discharged at request. Out of the 19 treated patients, all attained second CR. CR was consolidated with an autologous SCT (n=10) or ATO based chemotherapy (n=9). The OS and EFS of the 19 relapsed patients was 72.9±10.4% and 68±10.8% respectively.On long term follow up of this pediatric cohort (median follow up 71 months; 18 (26.5%) > 10 years follow up and 37 (54.5%) > 5 years follow up) there were no long term renal, hepatic, metabolic complications or second malignancies noted.Our results indicate the high efficacy and long term safety of ATO based regimens in the treatment of children with APL. Even among the relapse pediatric APL patients treated with upfront ATO, salvage chemotherapy with ATO based regimen followed by autologous stem cell transplantation is associated with excellent long term survival and is not associated with any major long term complications. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

PO-372 Investigating the epigenetic changes underlying combination treatment of acute promyelocytic leukaemia with all-trans retinoic acid and arsenic trioxide

IntroductionAcute promyelocytic leukaemia (APL) results in the interrupted differentiation of granulocytes. Combination induction therapy using all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) is the most effective treatment of APL. DNA methylation and histone modifications are epigenetic mechanisms of gene regulation aberrant in APL. While ATRA treatment of APL NB4 cells restores granulocyte differentiation and induces significant genome-wide changes in histone modifications, it does not affect the aberrant DNA methylation. Similarly, ATO has comparable effects. Therefore, we hypothesise that the increased effectiveness of ATRA and ATO when combined is due to epigenetic changes at both the histone and DNA methylation level, resulting in profound changes in gene expression.Material and methodsWe identified the concentration of ATRA and ATO in combination that induced enhanced differentiation and cell death of NB4 cells in comparison to single agent treatment through fluorescence activated cells sorting (FACS) of CD11b and 7-AAD labelled cells at 72 hours and 96 hours post treatment termination. Quantitative PCR (qPCR) was performed to determine the expression levels of a panel of genes after 72 hours of treatment and 96 hours post treatment termination.Results and discussionsATRA and ATO in combination induced significant differentiation and cell death of NB4 cells after 72 hours. Interestingly, only the combination-treated cells maintained differentiation when treatment was terminated for 96 hours. Additionally,combination treatment significantly increased the expression of several genes important in APL compared to single agent treatment after 72 hours as well as 96 hours post treatment termination. Chromatin immunoprecipitation (ChIP) is currently being utilised to investigate the enrichment of chromatin with acetylated and methylated histones, and qPCR was performed to assess the enrichment of several genes of interest. Finally, bisulfite pyrosequencing is being performed to characterise the specific methylation pattern of these genes of interest.ConclusionATRA and ATO in combination synergistically induces the differentiation of APL NB4 cells. Together, the ChIP and bisulfite pyrosequencing experiments will enable us to characterise the effects of combination treatment at the epigenetic level. Ultimately, understanding the epigenetic changes induced by ATO and ATRA synergy can help improve treatment in the clinic.