Redox, cysteines, and kinases-A triad sustaining myeloid leukemia.

Reactive oxygen species (ROS) work as a second messenger, modulating cell response and establishing homeostasis. Abrupt changes in ROS are used to modulate transient cell response to different stimuli, from viral infection to inflammation. Chronic exposure to high ROS concentration can cause cellular damage and promote the development of diseases. Leukemogenesis is adapted to high concentrations of ROS, hijacking the ROS system, and uses kinase cascades to promote survival advantages. The oxidation-reduction (redox) machinery is composed of enzymes that orchestrate all classes of protein and use available Cys as transmitters and sensors, to disseminate stress signals through cells via kinase cascades. Myeloid leukemias (MLs) are known for being a heterogeneous disease, and clonal diversity is remarkably characterized by differences in the activation of kinase-regulated signaling cascades to provide survival advantage. Stress-activated kinase cascades and other cascades are regulated by the ROS system. Several studies present nicotinamide adenine dinucleotide phosphate (NADPH) oxidase 2 (NOX2) and the ER-resident NOX4 as key elements of ROS activity in healthy myeloid cells and myeloid leukemia. Targeting ROS presents an attractive therapeutic strategy for (MLs) patients, but the boundaries between pro-apoptotic and anti-apoptotic ROS concentrations are not well established. Detailed understanding of the signaling switches that determine cell fate needs to be well understood. This work explores several aspects of the redox system and thiol-mediated reactions with focus on kinase signaling in myeloid cancers and highlights some of the challenges.

Azacitidine treatment for myeloid leukemia associated with Down syndrome: A nationwide retrospective study in Japan.

Hypomethylating agent treatment for myeloid leukemia associated with Down syndrome (ML-DS) has been scarcely reported. Herein, we collected information on azacitidine treatment for ML-DS in Japan. Forty-eight cycles of azacitidine treatment were performed for 12 patients, including 11 relapsed or refractory (R/R) patients. In 40 cycles, azacitidine was used as monotherapy. No azacitidine-related death was observed. One cycle concurrently administered with methotrexate-based intrathecal therapy was discontinued due to toxicities. Only 4 of the 19 cycles given in non-remission achieved complete or partial remission. In conclusion, although most toxicities were acceptable, azacitidine monotherapy might be insufficient for R/R ML-DS cases.

Guideline for treating relapsed or refractory myeloid leukemia in children with Down syndrome.

Treatment of relapsed and refractory myeloid leukemia in Down syndrome (r/r ML-DS) poses significant challenges, as prognosis is dire and there is no established standard treatment. This guideline provides treatment recommendations based on a literature review and collection of expert opinions, aiming to improve overall and event-free survival of patients. Treatment options include fludarabine and cytarabine (FLA) ± gemtuzumab ozogamicin (GO), azacytidine (AZA) ± panobinostat, and hematopoietic stem cell transplantation (HSCT). Preferred approaches are AZA ± panobinostat for cases with low blast count or FLA ± GO for cases with high blast count, followed by HSCT after remission. Further research is crucial for the investigation of targeted therapies (e.g., BH3 mimetics, LSD1, JAK inhibitors).

Nucleic acid therapeutics as differentiation agents for myeloid leukemias.

Differentiation therapy has proven to be a success story for patients with acute promyelocytic leukemia. However, the remaining subtypes of acute myeloid leukemia (AML) are treated with cytotoxic chemotherapies that have limited efficacy and a high likelihood of resistance. As differentiation arrest is a hallmark of AML, there is increased interest in developing differentiation-inducing agents to enhance disease-free survival. Here, we provide a comprehensive review of current reports and future avenues of nucleic acid therapeutics for AML, focusing on the use of targeted nucleic acid drugs to promote differentiation. Specifically, we compare and discuss the precision of small interfering RNA, small activating RNA, antisense oligonucleotides, and aptamers to modulate gene expression patterns that drive leukemic cell differentiation. We delve into preclinical and clinical studies that demonstrate the efficacy of nucleic acid-based differentiation therapies to induce leukemic cell maturation and reduce disease burden. By directly influencing the expression of key genes involved in myeloid maturation, nucleic acid therapeutics hold the potential to induce the differentiation of leukemic cells towards a more mature and less aggressive phenotype. Furthermore, we discuss the most critical challenges associated with developing nucleic acid therapeutics for myeloid malignancies. By introducing the progress in the field and identifying future opportunities, we aim to highlight the power of nucleic acid therapeutics in reshaping the landscape of myeloid leukemia treatment.

Survival outcomes of myeloid leukemia associated with Down syndrome and de novo acute myeloid leukemia in children: Experience from a single tertiary center in Thailand.

Few studies have reported the survival outcomes of myeloid leukemia associated with Down syndrome (DS) in resource-limited countries. This study aimed to compare characteristics and survival outcomes of children with acute myeloid leukemia (AML) between those with and without DS in Thailand. The medical records of AML patients aged 0-15 years treated in a major tertiary center in Southern Thailand between October 1978 and December 2019 were reviewed retrospectively. The overall (OS) and event-free survivals (EFS) rates were calculated using the Kaplan-Meier method. A total of 362 AML patients were included, of which 41 (11.3%) had DS. The mean age at diagnosis of the DS patients was 2.5 ± 1.9 years and most of them (90.2%) were under the age of five. The DS patients had lower initial white blood cell counts and peripheral blasts compared to the non-DS patients. The AML-M7 subtype was more common in the DS than in the non-DS patients (80.5% vs. 9.1%, p < 0.01, respectively). The 5-year OS and EFS rates of the DS patients were lower compared to the non-DS patients (12.9% vs. 20.5%, p = 0.05 and 13.7% vs. 18.4%, p = 0.03, respectively). DS patients had a significantly higher rate of early and treatment-related deaths compared to non-DS patients (30.3% vs. 13.5%, p < 0.01 and 39.4% vs. 19.5%, p = 0.02, respectively). Over the study period, there were a decrease in early death rate and an increase in survival rates of DS patients, which suggests that chemotherapy regimens and supportive care have improved over time.

CD45 inhibition in myeloid leukaemia cells sensitizes cellular responsiveness to chemotherapy.

Myeloid malignancies are a group of blood disorders characterized by the proliferation of one or more haematopoietic myeloid cell lineages, predominantly in the bone marrow, and are often caused by aberrant protein tyrosine kinase activity. The protein tyrosine phosphatase CD45 is a trans-membrane molecule expressed on all haemopoietic blood cells except that of platelets and red cells. CD45 regulates various cellular physiological processes including proliferation, apoptosis, and lymphocyte activation. However, its role in chemotherapy response is still unknown; therefore, the aim of this study was to investigate the role of CD45 in myeloid malignancies in terms of cellular growth, apoptosis, and response to chemotherapy. The expression of CD45 on myeloid leukaemia primary cells and cell lines was heterogeneous with HEL and OCI-AML3 cells showing the highest level. Inhibition of CD45 resulted in increased cellular sensitivity to cytarabine and ruxolitinib, the two main therapies for AML and MPN. Bioinformatics analysis identified genes whose expression was correlated with CD45 expression such as JAK2, ACTR2, THAP3 Serglycin, and PBX-1 genes, as well as licensed drugs (alendronate, allopurinol, and balsalazide), which could be repurposed as CD45 inhibitors which effectively increases sensitivity to cytarabine and ruxolitinib at low doses. Therefore, CD45 inhibition could be explored as a potential therapeutic partner for treatment of myeloid malignancies in combination with chemotherapy such as cytarabine especially for elderly patients and those showing chemotherapy resistance.

Effect of Petiveria alliacea Extracts on Metabolism of K562 Myeloid Leukemia Cells.

Previously, studies have shown that leukemic cells exhibit elevated glycolytic metabolism and oxidative phosphorylation in comparison to hematopoietic stem cells. These metabolic processes play a crucial role in the growth and survival of leukemic cells. Due to the metabolic plasticity of tumor cells, the use of natural products has been proposed as a therapeutic alternative due to their ability to attack several targets in tumor cells, including those that could modulate metabolism. In this study, the potential of Petiveria alliacea to modulate the metabolism of K562 cell lysates was evaluated by non-targeted metabolomics. Initially, in vitro findings showed that P. alliacea reduces K562 cell proliferation; subsequently, alterations were observed in the endometabolome of cell lysates treated with the extract, mainly in glycolytic, phosphorylative, lipid, and amino acid metabolism. Finally, in vitro assays were performed, confirming that P. Alliacea extract decreased the oxygen consumption rate and intracellular ATP. These results suggest that the anti-tumor activity of the aqueous extract on the K562 cell line is attributed to the decrease in metabolites related to cell proliferation and/or growth, such as nucleotides and nucleosides, leading to cell cycle arrest. Our results provide a preliminary part of the mechanism for the anti-tumor and antiproliferative effects of P. alliacea on cancer.

The miR-106b-25 cluster mediates drug resistance in myeloid leukaemias by inactivating multiple apoptotic genes.

Drug resistance is a major obstacle to the successful treatment of cancer. The role of the miR-106b-25 cluster in drug resistance of haematologic malignancies has not yet been elucidated. Here, we show that the miR-106b-25 cluster mediates resistance to therapeutic agents with structural and mechanistic dissimilarity in vitro and in vivo. RNA sequencing data revealed that overexpression of the miR-106b-25 cluster or its individual miRNAs resulted in downregulation of multiple key regulators of apoptotic pathways. Luciferase reporter assay identified TP73 as a direct target of miR-93 and miR-106b, BAK1 as a direct target of miR-25 and CASP7 as a direct target of all three miRNAs. We also showed that inhibitors of the miR-106b-25 cluster and BCL-2 exert synergistic effects on apoptosis induction in primary myeloid leukaemic cells. Thus, the members of the miR-106b-25 cluster may jointly contribute to myeloid leukaemia drug resistance by inactivating multiple apoptotic genes. Targeting this cluster could be a promising combination strategy in patients resistant to therapeutic agents that induce apoptosis.

Infectious complications after intensive chemotherapy with CLAG-M versus 7+3 for AML and other high-grade myeloid neoplasms.

Contemporary data on infections after intensive chemotherapy for acute myeloid leukemia (AML) are scarce. Cladribine, high-dose cytarabine, G-CSF, and dose-escalated mitoxantrone ("CLAG-M") may result in higher remission rates than standard-dose cytarabine plus anthracycline ("7 + 3") but may result in more infections. We compared moderate to severe infections occurring up to 90 days after the first induction cycle for AML or other high-grade myeloid neoplasms in patients receiving CLAG-M for newly diagnosed (n = 196) or relapsed/refractory disease (n = 131) or 7 + 3 for newly diagnosed disease (n = 115). For newly diagnosed disease, microbiologically documented infections were more frequent after CLAG-M compared to 7 + 3 (adjusted rate ratio, 1.65 [95% CI, 1.06-2.58]; P = 0.03), with a cumulative incidence of 27.8% and 16.5% by day 90, respectively. Patients receiving CLAG-M for relapsed/refractory disease had the highest cumulative incidence of 50.7%. Bacterial bloodstream infections were the most frequent followed by respiratory tract infections. Among 29 patients (7%) who died, infection was a primary or contributing cause of death in 59%. These data indicate that infections continue to cause substantial morbidity in patients treated for AML, especially those treated for relapsed/refractory disease, and are more common with newer, more myelosuppressive regimens such as CLAG-M. Improved strategies for infection prevention are needed.

1,4-Naphthoquinone (CNN1) Induces Apoptosis through DNA Damage and Promotes Upregulation of H2AFX in Leukemia Multidrug Resistant Cell Line.

The multidrug resistance (MDR) phenotype is one of the major obstacles in the treatment of chronic myeloid leukemia (CML) in advantage stages such as blast crisis. In this scenario, more patients develop resistance mechanisms during the course of the disease, making tyrosine kinase inhibitors (TKIs) target therapies ineffective. Therefore, the aim of the study was to examine the pharmacological role of CNN1, a para-naphthoquinone, in a leukemia multidrug resistant cell line. First, the in vitro cytotoxic activity of Imatinib Mesylate (IM) in K-562 and FEPS cell lines was evaluated. Subsequently, membrane integrity and mitochondrial membrane potential assays were performed to assess the cytotoxic effects of CNN1 in K-562 and FEPS cell lines, followed by cell cycle, alkaline comet assay and annexin V-Alexa Fluor® 488/propidium iodide assays (Annexin/PI) using flow cytometry. RT-qPCR was used to evaluate the H2AFX gene expression. The results demonstrate that CNN1 was able to induce apoptosis, cell membrane rupture and mitochondrial membrane depolarization in leukemia cell lines. In addition, CNN1 also induced genotoxic effects and caused DNA fragmentation, cell cycle arrest at the G2/M phase in leukemia cells. No genotoxicity was observed on peripheral blood mononuclear cells (PBMC). Additionally, CNN1 increased mRNA levels of H2AFX. Therefore, CNN1 presented anticancer properties against leukemia multidrug resistant cell line being a potential anticancer agent for the treatment of resistant CML.

Oxime derivative TFOBO promotes cell death by modulating reactive oxygen species and regulating NADPH oxidase activity in myeloid leukemia.

Several derivatives derived from the oxime structure have been reported as potential anticancer agents in various cancers. Here, we first tested a novel oxime-containing derivative of 2-((2,4,5-trifluorobenzyl)oxy)benzaldehyde oxime (TFOBO) to evaluate its anticancer effect in myeloid leukemic cells. Compared to (2-((2,4,5-trifluorobenzyl)oxy)phenyl)methanol (TFOPM), the oxime derivative TFOBO suppresses leukemic cell growth by significantly increasing reactive oxygen species (ROS) levels and cell death. Leukemic cells treated with TFOBO displayed apoptotic cell death, as indicated by nuclear condensation, DNA fragmentation, and annexin V staining. TFOBO increases Bax/Bcl2 levels, caspase9, and caspase3/7 activity and decreases mitochondrial membrane potential. ROS production was reduced by N-acetyl-L-cysteine, a ROS scavenger, diphenyleneiodonium chloride, a nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, after exogenous TFOBO treatment. ROS inhibitors protect leukemic cells from TFOBO-induced cell death. Thus, our study findings suggest that TFOBO promotes apoptosis by modulating ROS and regulating NADPH oxidase activity. Collectively, the oxime-containing derivative TFOBO is a novel therapeutic drug for myeloid leukemia.

Secondary chronic myeloid leukemia in a patient with CALR and ASXL1-mutated primary myelofibrosis.

Development of secondary CML has only been casually described, with few reports attempting to analyze and explain the mechanisms behind this phenomenon. Reported cases vary with regard to presumed pathogenesis and clinical characteristics, but similarities can be observed. This report presents the case of a patient diagnosed with CALR and ASXL1-mutated primary myelofibrosis who developed CML 13 years after the initial diagnosis. In contrast with previously reported cases, this patient did not have JAK2 or ABL1 gene mutations, and also exhibited primary resistance to tyrosine kinase inhibitor (TKI) treatment. Here, we analyze the molecular evolution of CML and describe successful treatment with concomitant therapy including a TKI and JAK inhibitor. This report aims to deepen clinical experience and further broaden knowledge about chronic myeloproliferative neoplasms.

SIRT2 regulates proliferation and chemotherapy response of MLL-ENL-driven acute myeloid leukemia.

Both MLL-AF9 and MLL-ENL leukemia fusion proteins drive oncogenic transformation of hematopoietic cells through their N-terminal DNA/histone binding mixed-lineage leukemia 1 domain and C-terminal fragment of AF9 or ENL containing an unstructured linker region and the ANC1 homology domain, which recruits transcription factors. Despite of their structural similarity, acute myeloid leukemia (AML) patients bearing MLL-ENL show more adverse outcomes compared to those with MLL-AF9. We recapitulated the clinical patterns of these two MLL-fusions driven AMLs using murine models and found that MLL-ENL AML cells showed slower cell cycle progression and more resistance to standard chemotherapy than MLL-AF9 cells. These phenotypes were primarily controlled by the linker regions of ENL and a highly conserved lysine residue K469 within. Substitution of K469 with an acetylated mimic glutamine abolished the ability of MLL-ENL to suppress proliferation and promote chemo-resistance. We showed that deacetylase Sirt2 might act as an upstream regulator of MLL-ENL. Deletion of Sirt2 promoted proliferation of AML cells with either MLL fusions. Importantly, loss of Sirt2 greatly enhanced the sensitivity of the MLL-ENL AML cells to chemo-treatment. Taken together, our study uncovered a unique regulatory role of Sirt2 in leukemogenesis and suggested targeting SIRT2 as a new way to sensitize MLL-ENL AML patience for chemotherapy.

Azoxystrobin Induces Apoptosis and Cell Cycle Arrest in Human Leukemia Cells Independent of p53 Expression.

BACKGROUND/AIM: Azoxystrobin (AZOX), a methoxyacrylate derivative, has potent antimicrobial and antitumor activities. Here, we report the anticancer effects of AZOX on the p53-negative human myelogenous leukemia cell line HL-60RG and the p53 positive human T-cell leukemia cell line MOLT-4F. MATERIALS AND METHODS: Using both leukemia cells, the anticancer effect of AZOX treatment was analyzed throughout the cell cycle. RESULTS: AZOX damaged both cell lines dose-dependently, and the cell damage rates were almost the same in both lines. Cell cycle distribution analysis showed that the treated MOLT-4F cells arrested at the S phase, whereas HL-60RG cells increased during the subG1 phase, suggesting that cell death was occurring. AZOX-induced cell death in HL-60RG was inhibited with the addition of uridine, which is used as a substrate for the salvage pathway of pyrimidine nucleotides. CONCLUSION: AZOX has p53-independent anticancer effects in leukemia cells, but the mechanisms underlying the damage differ between cell lines.

Early platelet elevation after complete remission as a prognostic marker of favourable outcomes in favourable- and intermediate-risk acute myeloid leukaemia: A retrospective study.

OBJECTIVES: Platelet (PLT) recovery after chemotherapy is associated with the prognosis of patients with acute myeloid leukaemia (AML). This study aimed to explore the prognostic significance of early high PLT values in patients with de novo non-M3 AML who achieved first complete remission (CR). METHODS: A total of 206 patients with de novo non-M3 AML were analysed in this retrospective study. A receiver operating characteristic (ROC) curve was used to determine the optimal PLT cut-off. The overall survival (OS) and relapse-free survival (RFS) were assessed using Kaplan-Meier and Cox regression analyses. RESULTS: 312×109 /L was confined as the cut-off of the PLT count. The estimated 3-year OS of patients with high PLT was higher than that of their counterparts (72.3% vs. 34.6%, p = 0.001). In subgroup analysis, patients with high PLT had better OS in the favourable- and intermediate-risk (non-adverse-risk) AML (p = 0.001). The estimated 3-year RFS for the high and low PLT groups was 75.1% and 45.7% respectively (p = 0.078). Multivariate analyses revealed that high PLT count was an independent favourable variable for OS (HR = 0.264, p < 0.001) and RFS (HR = 0.375, p = 0.011) in the non-adverse-risk group. CONCLUSION: Our results showed that early high PLT count recovery at first CR in non-adverse-risk AML patients is a positive prognostic marker for survival outcomes.

Maintenance therapy with hypomethylating agents for patients with acute myeloid leukemia in first remission not eligible for allogeneic hematopoietic cell transplantation: A systematic review and meta-analysis.

BACKGROUND: Older patients encompass about 75 % of patients with acute myeloid leukemia (AML). Today therapeutic options to prevent relapse in older patients who managed to achieve complete remission (CR) after intensive chemotherapy are scarce. Recent randomized controlled trials (RCTs) have aimed to reduce the risk of relapse by means of post-CR maintenance therapy. METHODS: We performed a systematic review and meta-analysis of RCTs comparing the efficacy and safety of maintenance with hypomethylating agents (HMA) vs. observation, conventional care or placebo in older patients with AML who are not candidates for allogeneic hematopoietic transplantation (allo-HCT). We searched Cochrane Library, PubMed and conference proceedings up to August 2021. RESULTS: Six trials were included. Treatment with hypomethylating agents significantly improved overall survival (HR 0.80, 95 % CI 0.70 to 0.91, I2 = 30 %), and disease control (HR 0.80, 95 % CI 0.70 to 0.91, I2 = 0). A significant decrease was seen in both one year mortality (Risk Ratio [RR] 0.61, 95 % CI 0.48 to 0.77, I2 = 0) and mortality at the end of follow-up (RR 0.77, 95 % CI 0.67 to 0.88, I2 = 0). The rate of relapse at 6 months and at one-two years was lower in the HMA arm vs. control (RR, 0.59; 95 % CI, 0.47-0.72; RR, 0.74, I2 = 0; 95 % CI 0.69 - 0.91, I2 = 41 %, respectively). HMA were associated with a statistically non-significant increase in the risk of serious adverse events (RR 3.44, 95 % CI 0.93-12.74, I2 = 80 %). CONCLUSIONS: Our meta-analysis shows that in older patients who are not candidates for allo-HCT, maintenance therapy with HMA improves OS and disease control without a statistically significant increase in adverse events.

Eliminating chronic myeloid leukemia stem cells by IRAK1/4 inhibitors.

Leukemia stem cells (LSCs) in chronic myeloid leukemia (CML) are quiescent, insensitive to BCR-ABL1 tyrosine kinase inhibitors (TKIs) and responsible for CML relapse. Therefore, eradicating quiescent CML LSCs is a major goal in CML therapy. Here, using a G0 marker (G0M), we narrow down CML LSCs as G0M- and CD27- double positive cells among the conventional CML LSCs. Whole transcriptome analysis reveals NF-κB activation via inflammatory signals in imatinib-insensitive quiescent CML LSCs. Blocking NF-κB signals by inhibitors of interleukin-1 receptor-associated kinase 1/4 (IRAK1/4 inhibitors) together with imatinib eliminates mouse and human CML LSCs. Intriguingly, IRAK1/4 inhibitors attenuate PD-L1 expression on CML LSCs, and blocking PD-L1 together with imatinib also effectively eliminates CML LSCs in the presence of T cell immunity. Thus, IRAK1/4 inhibitors can eliminate CML LSCs through inhibiting NF-κB activity and reducing PD-L1 expression. Collectively, the combination of TKIs and IRAK1/4 inhibitors is an attractive strategy to achieve a radical cure of CML.

A phase II study of sequential decitabine and rapamycin in acute myelogenous leukemia.

A phase II study was conducted to ascertain whether sequential exposure to decitabine followed by rapamycin, an mTOR (mechanistic target of rapamycin) inhibitor would result in better responses than decitabine alone. Newly diagnosed acute myelogenous leukemia (AML) patients who were >65 years old and not eligible for intensive induction regimens or patients with relapsed or refractory AML received 10 days of decitabine followed by 12 days of rapamycin in cycle 1 and 5 days of decitabine followed by 17 days of rapamycin in subsequent cycles. The composite complete remission rate (CR) was 33 % (CR plus CR with incomplete count recovery). Median overall survival was 7.7 months in newly diagnosed elderly AML patients and 6.6 months in relapsed/refractory AML patients. Twenty-four evaluable patients were enrolled, and the study did not meet its primary endpoint of demonstrating a significant improvement in composite CR rate with the combination as compared to an established historical CR rate of 25 % with decitabine alone. Despite that, the survival rates in relapsed/refractory cases appear comparable to what is reported with other salvage regimens, and no significant patterns of non-hematologic toxicity were noted. 50 % of subjects in the de novo group achieved a composite CR which is significantly higher (p = 0.02) than the rate of 25 % with decitabine alone. This trial is registered at clinical trials.gov as NCT02109744.