The epigenetic landscape of acute myeloid leukemia

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).

Crosstalk between genomic variants and DNA methylation in FLT3 mutant acute myeloid leukemia

Acute myeloid leukemia (AML) is a type of blood cancer with diverse genetic variations and DNA methylation alterations. By studying the interaction of gene mutations, expression, and DNA methylation, we aimed to gain valuable insights into the processes that lead to block differentiation in AML. We analyzed TCGA-LAML data (173 samples) with RNA sequencing and DNA methylation arrays, comparing FLT3 mutant (48) and wild-type (125) cases. We conducted differential gene expression analysis using cBioPortal, identified DNA methylation differences with ChAMP tool, and correlated them with gene expression changes. Gene set enrichment analysis (g:Profiler) revealed significant biological processes and pathways. ShinyGo and GeneCards were used to find potential transcription factors and their binding sites among significant genes. We found significant differentially expressed genes (DEGs) negatively correlated with their most significant methylation probes (Pearson correlation coefficient of -0.49, P-value <0.001) between FLT3 mutant and wild-type groups. Moreover, our exploration of 450 k CpG sites uncovered a global hypo-methylated status in 168 DEGs. Notably, these methylation changes were enriched in the promoter regions of Homebox superfamily gene, which are crucial in transcriptional-regulating pathways in blood cancer. Furthermore, in FLT3 mutant AML patient samples, we observed overexpress of WT1, a transcription factor known to bind homeobox gene family. This finding suggests a potential mechanism by which WT1 recruits TET2 to demethylate specific genomic regions. Integrating gene expression and DNA methylation analyses shed light on the impact of FLT3 mutations on cancer cell development and differentiation, supporting a two-hit model in AML. This research advances understanding of AML and fosters targeted therapeutic strategy development.

Emerging DNA Methylome Targets in FLT3-ITD-Positive Acute Myeloid Leukemia: Combination Therapy with Clinically Approved FLT3 Inhibitors

OPINION STATEMENT

The internal tandem duplication (ITD) mutation of the FMS-like receptor tyrosine kinase 3 (FLT3-ITD) is the most common mutation observed in approximately 30% of acute myeloid leukemia (AML) patients. It represents poor prognosis due to continuous activation of downstream growth-promoting signaling pathways such as STAT5 and PI3K/AKT. Hence, FLT3 is considered an attractive druggable target; selective small FLT3 inhibitors (FLT3Is), such as midostaurin and quizartinib, have been clinically approved. However, patients possess generally poor remission rates and acquired resistance when FLT3I used alone. Various factors in patients could cause these adverse effects including altered epigenetic regulation, causing mainly abnormal gene expression patterns. Epigenetic modifications are required for hematopoietic stem cell (HSC) self-renewal and differentiation; however, critical driver mutations have been identified in genes controlling DNA methylation (such as DNMT3A, TET2, IDH1/2). These regulators cause leukemia pathogenesis and affect disease diagnosis and prognosis when they co-occur with FLT3-ITD mutation. Therefore, understanding the role of different epigenetic alterations in FLT3-ITD AML pathogenesis and how they modulate FLT3I's activity is important to rationalize combinational treatment approaches including FLT3Is and modulators of methylation regulators or pathways. Data from ongoing pre-clinical and clinical studies will further precisely define the potential use of epigenetic therapy together with FLT3Is especially after characterized patients' mutational status in terms of FLT3 and DNA methlome regulators.

Lower Levels of TET2 Gene Expression, with a Higher Level of TET2 Promoter Methylation in Patients with AML; Evidence for the Role of Aberrant Methylation in AML Pathogenesis

DNA methylation is a key epigenetic mechanism that is dysregulated in leukemia and plays a significant role in leukemogenesis. Ten-eleven translocation 2 (TET2) is one of the most frequently mutated genes among the DNA methylation regulators in hematologic malignancies, indicating its tumor-suppressor function. In this study, we investigated the expression and methylation status of TET2 in patients with AML. Quantitative RT-PCR was used to evaluate TET2 expression in peripheral blood mononuclear cells (PBMCs) from 51 newly diagnosed AML patients and 50 healthy controls. The methylation-sensitive high-resolution melting (MS-HRM) method was used in 45 patients with AML and 15 healthy controls to evaluate the promoter methylation of TET2. TET2 expression was significantly downregulated (P < 0.0001) in patients with AML compared to that in healthy controls. Furthermore, the methylation level of the TET2 promoter was significantly different between patients and controls. Aberrant methylation of the TET2 promoter was observed in 53.3% of the patients. Interestingly, a negative (- 0.3138) and significant (P = 0.0358) correlation between TET2 methylation and expression was found. The survival of patients with downregulated TET2 was poorer than that of other patients. TET2 gene expression was significantly downregulated while the promoter methylation was higher in patients, indicating that TET2 may be a tumor suppressor gene and a prognostic factor in AML and that transcriptional silencing of the TET2 gene may play a role in AML pathogenesis. Since epigenetic mechanisms are reversible, abnormal TET2 methylation could become a therapeutic target in the future.

Biological activities of extracts and compounds from Thai Kae-Lae (Maclura cochinchinensis (Lour.) Corner)

BACKGROUND AND AIMS

The purpose of this study was to investigate the biological properties of Kae-Lae (Maclura cochinchinensis (Lour.) Corner), a traditional medicinal plant used in Ayurvedic recipes in Thailand. To achieve this objective, heartwood samples were collected from 12 sources across Thailand. Fractional extracts (n-hexane, ethyl acetate, and ethanol) and the dominant compounds (morin, resveratrol, and quercetin) were examined for their abilities on cytotoxicity, antioxidant, anti-inflammation, and antileukaemic activity (Wilms' tumour 1 protein was used as a well-known biomarker for leukaemic cell proliferation).

METHODS

The study used MTT to assess cytotoxicity in leukaemic cells (K562, EoL-1, and KG-1a). Antioxidant activities were evaluated using ABTS, DPPH, and FRAP assays. The anti-inflammatory activity was investigated by detecting IL-2, TNF-α, and NO using appropriate detection kits. Wilms' tumour 1 protein expression was measured by Western blotting to determine the anti-leukaemic activity. The inhibition of cell migration was also analyzed to confirm anticancer progression.

RESULTS

Among the tested extract fraction, ethyl acetate No. 001 displayed strong cytotoxicity specifically in EoL-1 cells, while n-hexane No. 008 demonstrated this effect in three cell lines. Resveratrol, on the other hand, displayed cytotoxicity in all the tested cells. Additionally, the three major compounds, morin, resveratrol, and quercetin, exhibited significant antioxidant and anti-inflammatory properties. In particular, resveratrol demonstrated a noteworthy decreased Wilms' tumour 1 protein expression and a reduction in cell proliferation across all cells. Moreover, ethyl acetate No. 001, morin, and resveratrol effectively inhibited MCF-7 cell migration. None of these compounds showed any impact on red blood cell haemolysis.

CONCLUSION

Based on these findings, it can be concluded that Kae-Lae has promising chemotherapeutic potential against leukaemic cells, with fractional extracts (ethyl acetate and n-hexane) and resveratrol exhibiting the most potent cytotoxic, antioxidant, anti-inflammatory, and anti-cell migration activities.

Dual inhibition of EZH2 and G9A/GLP histone methyltransferases by HKMTI-1-005 promotes differentiation of acute myeloid leukemia cells

All-trans-retinoic acid (ATRA)-based differentiation therapy of acute promyelocytic leukemia (APL) represents one of the most clinically effective examples of precision medicine and the first example of targeted oncoprotein degradation. The success of ATRA in APL, however, remains to be translated to non-APL acute myeloid leukemia (AML). We previously showed that aberrant histone modifications, including histone H3 lysine 4 (H3K4) and lysine 27 (H3K27) methylation, were associated with this lack of response and that epigenetic therapy with small molecule inhibitors of the H3K4 demethylase LSD1/KDM1A could reprogram AML cells to respond to ATRA. Serving as the enzymatic component of Polycomb Repressive Complex 2, EZH2/KMT6A methyltransferase plays a critical role in normal hematopoiesis by affecting the balance between self-renewal and differentiation. The canonical function of EZH2 is methylation of H3K27, although important non-canonical roles have recently been described. EZH2 mutation or deregulated expression has been conclusively demonstrated in the pathogenesis of AML and response to treatment, thus making it an attractive therapeutic target. In this study, we therefore investigated whether inhibition of EZH2 might also improve the response of non-APL AML cells to ATRA-based therapy. We focused on GSK-343, a pyridone-containing S-adenosyl-L-methionine cofactor-competitive EZH2 inhibitor that is representative of its class, and HKMTI-1-005, a substrate-competitive dual inhibitor targeting EZH2 and the closely related G9A/GLP H3K9 methyltransferases. We found that treatment with HKMTI-1-005 phenocopied EZH2 knockdown and was more effective in inducing differentiation than GSK-343, despite the efficacy of GSK-343 in terms of abolishing H3K27 trimethylation. Furthermore, transcriptomic analysis revealed that in contrast to treatment with GSK-343, HKMTI-1-005 upregulated the expression of differentiation pathway genes with and without ATRA, while downregulating genes associated with a hematopoietic stem cell phenotype. These results pointed to a non-canonical role for EZH2, which was supported by the finding that EZH2 associates with the master regulator of myeloid differentiation, RARα, in an ATRA-dependent manner that was enhanced by HKMTI-1-005, possibly playing a role in co-regulator complex exchange during transcriptional activation. In summary, our results strongly suggest that addition of HKMTI-1-005 to ATRA is a new therapeutic approach against AML that warrants further investigation.

RUNX1/CEBPA Mutation in Acute Myeloid Leukemia Promotes Hypermethylation and Indicates for Demethylation Therapy

Acute myeloid leukemia (AML) is a rapidly progressing heterogeneous disease with a high mortality rate, which is characterized by hyperproliferation of atypical immature myeloid cells. The number of AML patients is expected to increase in the near future, due to the old-age-associated nature of AML and increased longevity in the human population. RUNX1 and CEBPA, key transcription factors (TFs) of hematopoiesis, are frequently and independently mutated in AML. RUNX1 and CEBPA can bind TET2 demethylase and attract it to their binding sites (TFBS) in cell lines, leading to DNA demethylation of the regions nearby. Since TET2 does not have a DNA-binding domain, TFs are crucial for its guidance to target genomic locations. In this paper, we show that RUNX1 and CEBPA mutations in AML patients affect the methylation of important regulatory sites that resulted in the silencing of several RUNX1 and CEBPA target genes, most likely in a TET2-dependent manner. We demonstrated that hypermethylation of TFBS in AML cells with RUNX1 mutations was associated with resistance to anticancer chemotherapy. Demethylation therapy restored expression of the RUNX1 target gene, BIK, and increased sensitivity of AML cells to chemotherapy. If our results are confirmed, mutations in RUNX1 could be an indication for prescribing the combination of cytotoxic and demethylation therapies.

Analysis of rare driving events in pediatric acute myeloid leukemia

Elucidating genetic aberrations in pediatric acute myeloid leukemia (AML) provides insight in biology and may impact on risk-group stratification and clinical outcome. This study aimed to detect such aberrations in a selected series of samples without known (cyto)genetic aberration using molecular profiling. A cohort of 161 patients was selected from various study groups: DCOG, BFM, SJCRH, NOPHO and AEIOP. Samples were analyzed using RNA sequencing (n=152), whole exome (n=135) and/or whole genome sequencing (n=100). In 70 of 156 patients (45%), of whom RNA sequencing or whole genome sequencing was available, rearrangements were detected, 22 of which were novel; five involving ERG rearrangements and four NPM1 rearrangements. ERG rearrangements showed self-renewal capacity in vitro, and a distinct gene expression pattern. Gene set enrichment analysis of this cluster showed upregulation of gene sets derived from Ewing sarcoma, which was confirmed comparing gene expression profiles of AML and Ewing sarcoma. Furthermore, NPM1-rearranged cases showed cytoplasmic NPM1 localization and revealed HOXA/B gene overexpression, as described for NPM1 mutated cases. Single-gene mutations as identified in adult AML were rare. Patients had a median of 24 coding mutations (range, 7-159). Novel recurrent mutations were detected in UBTF (n=10), a regulator of RNA transcription. In 75% of patients an aberration with a prognostic impact could be detected. Therefore, we suggest these techniques need to become standard of care in diagnostics.

Proviral Integration of Moloney Virus-2 (PIM-2) Expression Level as a Prognostic Marker in Patients with Acute Myeloid Leukemia

Purpose

This study aimed to assess PIM-2 gene expression level as a prognostic marker in AML patients and to correlate the results with their clinical outcome.

Patients and Methods

This study was conducted on 50 de novo younger AML patients (median age 44). Quantitative real-time polymerase chain reaction (QRT-PCR) was used to assess the expression level of the PIM-2 gene. The transcription level of the target gene (PIM-2) was normalized to that of the reference gene (GAPDH). Twenty control samples were withdrawn from 20 age- and sex-matched individuals for the analysis of the results using the 2^−ΔΔCT method. On day 28 following induction chemotherapy, patients’ bone marrow (BM) was examined for evaluation of their remission status.

Results

PIM-2 gene expression was higher among AML patients who did not achieve complete remission (CR); also, it was higher in patients in the intermediate and poor cytogenetic risk groups. A significant positive correlation was found between PIM-2 level and BM blasts on day 28. In AML patients, PIM-2 has been discovered to be an independent predictive factor for achieving CR following standard induction treatment. Receiver operating characteristic curve (ROC) and area under the curve (AUC) were performed for PIM-2 level at diagnosis to evaluate its role in achieving remission after induction. It was found that PIM-2 at cutoff ≤1.6 had an AUC (0.903) with a sensitivity (90.48%) and specificity (86.21%), P <0.001.

Conclusion

Overexpression of the PIM-2 gene is associated with induction failure and low CR.

Diagnostic and Prognostic Power of Active DNA Demethylation Pathway Intermediates in Acute Myelogenous Leukemia and Myelodysplastic Syndromes

Acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS) are characterized by genomic instability, which may arise from the global hypomethylation of the DNA. The active DNA demethylation process may be linked with aberrant methylation and can be involved in leukemogenesis. The levels of 5-methylcytosine oxidation products were analyzed in minimally invasive material: the cellular DNA from peripheral blood cells and urine of patients with AML and MDS along with the control group, using isotope-dilution two-dimensional ultra-performance liquid chromatography with tandem mass spectrometry. The receiver operating characteristic curve analysis was used for the assessment of the ability to discriminate patients’ groups from the control group, and AML from MDS. The most diagnostically useful for discriminating AML patients from the control group was the urinary excretion of 5-hydroxymethylcytosine (AUC = 0.918, sensitivity: 85%, and specificity: 97%), and 5-(hydroxymethyl)-2′-deoxyuridine (0.873, 74%, and 92%), while for MDS patients 5-(hydroxymethyl)-2′-deoxycytidine in DNA (0.905, 82%, and 98%) and urinary 5-hydroxymethylcytosine (0.746, 66%, and 92%). Multi-factor models of classification trees allowed the correct classification of patients with AML and MDS in 95.7% and 94.7% of cases. The highest prognostic value of the analyzed parameters in predicting the transformation of MDS into AML was observed for 5-carboxy-2′-deoxycytidine (0.823, 80%, and 97%) and 5-(hydroxymethyl)-2′-deoxyuridine (0.872, 100%, and 75%) in DNA. The presented research proves that the intermediates of the active DNA demethylation pathway determined in the completely non-invasive (urine) or minimally invasive (blood) material can be useful in supporting the diagnostic process of patients with MDS and AML. The possibility of an early identification of a group of MDS patients with an increased risk of transformation into AML is of particular importance.

Molecular Systems Architecture of Interactome in the Acute Myeloid Leukemia Microenvironment

A molecular systems architecture is presented for acute myeloid leukemia (AML) to provide a framework for organizing the complexity of biomolecular interactions. AML is a multifactorial disease resulting from impaired differentiation and increased proliferation of hematopoietic precursor cells involving genetic mutations, signaling pathways related to the cancer cell genetics, and molecular interactions between the cancer cell and the tumor microenvironment, including endothelial cells, fibroblasts, myeloid-derived suppressor cells, bone marrow stromal cells, and immune cells (e.g., T-regs, T-helper 1 cells, T-helper 17 cells, T-effector cells, natural killer cells, and dendritic cells). This molecular systems architecture provides a layered understanding of intra- and inter-cellular interactions in the AML cancer cell and the cells in the stromal microenvironment. The molecular systems architecture may be utilized for target identification and the discovery of single and combination therapeutics and strategies to treat AML.

Genome-wide regulation of CpG methylation by ecCEBPα in acute myeloid leukemia

Background: Acute myeloid leukemia (AML) is a hematopoietic malignancy characterized by genetic and epigenetic aberrations that alter the differentiation capacity of myeloid progenitor cells. The transcription factor CEBPα is frequently mutated in AML patients leading to an increase in DNA methylation in many genomic locations. Previously, it has been shown that ecCEBPα (extra coding CEBP α) - a lncRNA transcribed in the same direction as CEBPα gene - regulates DNA methylation of CEBPα promoter in cis. Here, we hypothesize that ecCEBPα could participate in the regulation of DNA methylation in trans.

Method: First, we retrieved the methylation profile of AML patients with mutated CEBPα locus from The Cancer Genome Atlas (TCGA). We then predicted the ecCEBPα secondary structure in order to check the potential of ecCEBPα to form triplexes around CpG loci and checked if triplex formation influenced CpG methylation, genome-wide.

Results: Using DNA methylation profiles of AML patients with a mutated CEBPα locus, we show that ecCEBPα could interact with DNA by forming DNA:RNA triple helices and protect regions near its binding sites from global DNA methylation. Further analysis revealed that triplex-forming oligonucleotides in ecCEBPα are structurally unpaired supporting the DNA-binding potential of these regions. ecCEBPα triplexes supported with the RNA-chromatin co-localization data are located in the promoters of leukemia-linked transcriptional factors such as MLF2.

Discussion: Overall, these results suggest a novel regulatory mechanism for ecCEBPα as a genome-wide epigenetic modulator through triple-helix formation which may provide a foundation for sequence-specific engineering of RNA for regulating methylation of specific genes.

Comprehensive analysis of mutations and clonal evolution patterns in a cohort of patients with cytogenetically normal acute myeloid leukemia

Background

Relapsed acute myeloid leukemia (AML) is associated with the acquisition of additional somatic mutations which are thought to drive phenotypic adaptability, clonal selection and evolution of leukemic clones during treatment. We performed high throughput exome sequencing of matched presentation and relapsed samples from 6 cytogenetically normal AML (CN-AML) patients treated with standard remission induction chemotherapy in order to contribute with the investigation of the mutational landscape of CN-AML and clonal evolution during AML treatment.

Result

A total of 24 and 32 somatic variants were identified in presentation and relapse samples respectively with an average of 4.0 variants per patient at presentation and 5.3 variants per patient at relapse, with SNVs being more frequent than indels at both disease stages. All patients have somatic variants in at least one gene that is frequently mutated in AML at both disease presentation and relapse, with most of these variants are classic AML and recurrent hotspot mutations including NPM1 p.W288fs, FLT3-ITD, NRAS p.G12D and IDH2 p.R140Q. In addition, we found two distinct clonal evolution patterns of relapse: (1) a leukemic clone at disease presentation acquires additional mutations and evolves into the relapse clone after the chemotherapy; (2) a leukemic clone at disease presentation persists at relapse without the addition of novel somatic mutations.

Conclusions

The findings of this study suggest that the relapse-initiating clones may pre-exist prior to therapy, which harbor or acquire mutations that confer selective advantage during chemotherapy, resulting in clonal expansion and eventually leading to relapse.

RUNX1 Upregulates CENPE to Promote Leukemic Cell Proliferation

RUNX1 is a Runt family transcription factor that plays a critical role in normal hematopoiesis, including the differentiation and proliferation of hematopoietic cells. RUNX1 mutations, including chromosomal translocations, cause abnormal cell differentiation, but the mutation alone is not sufficient to cause leukemia. In MLL-fusion-induced leukemia, dysregulated wild-type RUNX1 can promote leukemia survival. Nevertheless, the underlying mechanisms of dysregulated wild-type RUNX1 in leukemia development have not been fully elucidated. This study overexpressed and knocked down RUNX1 expression in THP-1 human leukemia cells and CD34⁺ hematopoietic stem/progenitor cells to investigate the biological functions affected by dysregulated RUNX1. Our data indicated RUNX1 facilitated proliferation to promote leukemia cell growth. Furthermore, we demonstrated that RUNX1 knockdown in leukemia cells drastically diminished colony-forming ability. Finally, the RUNX1-knocked down cell depletion phenotype could be rescued by overexpression of CENPE, a cell proliferation gene and a RUNX1 direct target gene. Our results indicate a possible mechanism involving the RUNX1-CENPE axis on promoting leukemic cell growth.

Genetics of donor cell leukemia in acute myelogenous leukemia and myelodysplastic syndrome

Allogeneic hematopoietic stem cell transplantation (HSCT) is an important therapeutic modality for patients with acute myelogenous leukemia (AML) with poor risk features. Nonetheless, roughly 30% of such patients have leukemia recurrence and up to 2% of these are donor-derived leukemias, in which malignancy develops in the donor's transplanted cells, despite extremely low rates of leukemia in the donors themselves. Notably, over 20% of these malignancies carry chromosome 7 abnormalities nearly all of which are monosomies. Recent advances in whole exome and genome sequencing have allowed for detection of candidate genes that likely contribute to the development of AML in donor cells (donor leukemia, DCL). These genes include CEBPA, GATA2, JAK2, RUNX1, DDX41, EZH2, IDH1/2, DNMT3A, ASXL1, XPD, XRCC3, and CHEK1. The potential roles of variants in these genes are evaluated based on familial clustering of MDS/AML and corresponding animal studies demonstrating their leukemogenic nature. This review describes the spectrum of genetic aberrations detected in DCL cases in the literature with regard to the character of the individual cases, existing family cohorts that carry individual genes, and functional studies that support etiologic roles in AML development. DCL presents a unique opportunity to examine genetic variants in the donors and recipients with regards to progression to malignancy.

(2R,3S)-Dihydroxybutanoic Acid Synthesis as a Novel Metabolic Function of Mutant Isocitrate Dehydrogenase 1 and 2 in Acute Myeloid Leukemia

Simple Summary

Acute myeloid leukemia (AML) is one of several cancers where cancer proliferation occurs under the influence of an aberrant metabolite known as an oncometabolite produced by a mutated enzyme in the cancer cell. In AML, mutant isocitrate dehydrogenases produce the oncometabolite 2-hydroxyglutarate. We screened AML patients with and without mutant isocitrate dehydrogenases by using a technique known as metabolomics, which measures many different metabolites in patient plasma. It was observed that another metabolite, 2,3-dihydroxybutyrate, was produced in larger amounts in patients with mutated isocitrate dehydrogenase and correlated strongly with 2-hydroxyglutarate levels. Moreover, 2,3-dihydroxybutyrate was a better indicator of the presence of mutated isocitrate dehydrogenase in the cancer than the known oncometabolite 2-hydroxyglutarate. These findings may lead to the characterization of 2,3-dihydroxybutyrate as a novel oncometabolite in AML, which would bring a fuller understanding of the etiology of this disease and offer opportunities for the development of novel therapeutic agents.

Abstract

Acute myeloid leukemia (AML) frequently harbors mutations in isocitrate 1 (IDH1) and 2 (IDH2) genes, leading to the formation of the oncometabolite (2R)-hydroxyglutaric acid (2R-HG) with epigenetic consequences for AML proliferation and differentiation. To investigate if broad metabolic aberrations may result from IDH1 and IDH2 mutations in AML, plasma metabolomics was conducted by gas chromatography–mass spectrometry (GC–MS) on 51 AML patients, 29 IDH1/2 wild-type (WT), 9 with IDH1R132, 12 with IDH2R140 and one with IDH2R172 mutations. Distinct metabolic differences were observed between IDH1/2 WT, IDH1R132 and IDH2R140 patients that comprised 22 plasma metabolites that were mainly amino acids. Only two plasma metabolites were statistically significantly different (p < 0.0001) between both IDH1R132 and WT IDH1/2 and IDH2R140 and WT IDH1/2, specifically (2R)-hydroxyglutaric acid (2R-HG) and the threonine metabolite (2R,3S)-dihydroxybutanoic acid (2,3-DHBA). Moreover, 2R-HG correlated strongly (p < 0.0001) with 2,3-DHBA in plasma. One WT patient was discovered to have a D-2-hydroxyglutarate dehydrogenase (D2HGDH) A426T inactivating mutation but this had little influence on 2R-HG and 2,3-DHBA plasma concentrations. Expression of transporter genes SLC16A1 and SLC16A3 displayed a weak correlation with 2R-HG but not 2,3-DHBA plasma concentrations. Receiver operating characteristic (ROC) analysis demonstrated that 2,3-DHBA was a better biomarker for IDH mutation than 2R-HG (Area under the curve (AUC) 0.861; p < 0.0001; 80% specificity; 87.3% sensitivity). It was concluded that 2,3-DHBA and 2R-HG are both formed by mutant IDH1R132, IDH2R140 and IDH2R172, suggesting a potential role of 2,3-DHBA in AML pathogenesis.

Deciphering the role of Wnt signaling in acute myeloid leukemia prognosis: how alterations in DNA methylation come into play in patients' prognosis

Acute myeloid leukemia (AML) is a malignant clonal disorder affecting myeloid differentiation through mechanisms that include epigenetic dysregulation. Abnormal changes in DNA methylation and gene expression profiles of pathways involved in hematopoietic development, such as Wnt/β-catenin, contribute to the transformation, development, and maintenance of leukemic cells. This review summarizes the alterations of Wnt signaling-related genes at the epigenetic and transcriptional level and their implications for AML prognosis. Among the implications of epigenetic alterations in AML, methylation of Wnt antagonists is related to poor prognosis, whereas their upregulation has been associated with a better clinical outcome. Furthermore, Wnt target genes c-Myc and LEF-1 present distinct implications. LEF-1 expression positively influences the patient overall survival. c-Myc upregulation has been associated with treatment resistance in AML, although c-Myc expression is not exclusively dependent of Wnt signaling. Understanding the signaling abnormalities could help us to further understand leukemogenesis, improve the current risk stratification for AML patients, and even serve to propose novel therapeutic targets.

Comparison of SF3B1/DNMT3A Comutations With DNMT3A or SF3B1 Mutation Alone in Myelodysplastic Syndrome and Clonal Cytopenia of Undetermined Significance

OBJECTIVES

To compare the clinical significance of SF3B1/DNMT3A Comutations with SF3B1 or DNMT3A mutation alone in myelodysplastic syndrome (MDS) and clonal cytopenia of undetermined significance (CCUS).

METHODS

We identified and compared 31 patients with only DNMT3A mutation, 48 patients with only SF3B1 mutation, and 16 patients with only SF3B1/DNMT3A comutations.

RESULTS

SF3B1/DNMT3A comutations were found to be more common in MDS, whereas DNMT3A mutation alone was more common in CCUS. The patients with SF3B1/DNMT3A comutations were less likely to have poor cytogenetics than patients with DNMT3A mutation alone. Patients with SF3B1/DNMT3A comutations showed significantly longer median survival time and better overall survival than patients with DNMT3A mutation alone.

CONCLUSIONS

Patients with SF3B1/DNMT3A comutations appear to have better clinical outcomes than patients with isolated DNMT3A mutation. These findings suggest that the favorable prognosis of SF3B1 mutation in is not abrogated by the concurrent presence of a DNMT3A mutation.

Classic and targeted anti-leukaemic agents interfere with the cholesterol biogenesis metagene in acute myeloid leukaemia: Therapeutic implications

Despite significant advances in deciphering the molecular landscape of acute myeloid leukaemia (AML), therapeutic outcomes of this haematological malignancy have only modestly improved over the past decades. Drug resistance and disease recurrence almost invariably occur, highlighting the need for a deeper understanding of these processes. While low O₂ compartments, such as bone marrow (BM) niches, are well‐recognized hosts of drug‐resistant leukaemic cells, standard in vitro studies are routinely performed under supra‐physiologic (21% O₂, ambient air) conditions, which limits clinical translatability. We hereby identify molecular pathways enriched in AML cells that survive acute challenges with classic or targeted therapeutic agents. Experiments took into account variations in O₂ tension encountered by leukaemic cells in clinical settings. Integrated RNA and protein profiles revealed that lipid biosynthesis, and particularly the cholesterol biogenesis branch, is a particularly therapy‐induced vulnerability in AML cells under low O₂ states. We also demonstrate that the impact of the cytotoxic agent cytarabine is selectively enhanced by a high‐potency statin. The cholesterol biosynthesis programme is amenable to additional translational opportunities within the expanding AML therapeutic landscape. Our findings support the further investigation of higher‐potency statin (eg rosuvastatin)–based combination therapies to enhance targeting residual AML cells that reside in low O₂ environments.

Targeting acute myeloid leukemia stem cells: Current therapies in development and potential strategies with new dimensions

High relapse rate of acute myeloid leukemia (AML) is still a crucial problem despite considerable advances in anti-cancer therapies. One crucial cause of relapse is the existence of leukemia stem cells (LSCs) with self-renewal ability, which contribute to repeated treatment resistance and recurrence. Treatments targeting LSCs, especially in combination with existing chemotherapy regimens or hematopoietic stem cell transplantation might help achieve a higher complete remission rate and improve overall survival. Many novel agents of different therapeutic strategies that aim to modulate LSCs self-renewal, proliferation, apoptosis, and differentiation are under investigation. In this review, we summarize the latest advances of different therapies in development based on the biological characteristics of LSCs, with particular attention on natural products, synthetic compounds, antibody therapies, and adoptive cell therapies that promote the LSC eradication. We also explore the causes of AML recurrence and proposed potential strategies with new dimensions for targeting LSCs in the future.

Adopting solutions for annotation and reporting of next generation sequencing in clinical practice

With advancements in the understanding of human cancers (carcinomas, sarcomas, and hematopoietic malignancies), molecular profiling, especially by Next Generation Sequencing (NGS), is playing an increasingly important role in the diagnosis, prognostication, and therapeutic management of cancer patients. The final and critical step in NGS is the annotation of detected variants and reporting of their clinical significance. Automated bioinformatics tools are available to assist with annotation, but the final responsibility for interpretation and validation of the annotation rests with the pathologist who may be constrained by the pressures of clinical sign-out and limited training in NGS. In this manuscript, we detail our experience in outsourcing variant annotation to a high-quality vendor to improve quality, standardize reporting, and decrease turn-around time of NGS reporting in clinical practice. We describe the composition of the evaluation team, steps that should be taken to evaluate potential annotation vendors, and detailed parameters that should be addressed before contracting with a vendor to guarantee the clinical reliability of the reported annotations.

Detection Of Mutations In The Isocitrate Dehydrogenase Genes (IDH1/IDH2) Using castPCRTM In Patients With AML And Their Clinical Impact In Mexico City

Objective

Approximately 40–50% of patients with acute myeloid leukaemia (AML) have been reported to present with a normal karyotype and a variable disease-free period, most likely due to the molecular heterogeneity presented by these patients. A variety of mutations have been identified at the molecular level, such as those in the IDH1/2 gene, which causes a gain of function of the isocitrate dehydrogenase enzyme, generating high levels of the (R)-2-hydroxyglutarate oncometabolite, which competitively inhibits dioxygenase enzymes. Therefore, the objective of this study was to evaluate the incidence of IDH1/2 gene mutations in AML patients and their impact on survival.

Materials and methods

A total of 101 patients with a diagnosis of AML were included; mononuclear cells were obtained for DNA extraction and purification. Mutations were detected using TaqMan™ competitive allele-specific probes (castPCR™). Overall survival curves were plotted using IBM SPSS Statistics 23 software.

Results

The frequency of IDH gene mutations was 19.8%. For the IDH1 gene, 13.8% of the mutations identified included R132H, V178I, G105G and R132C. The frequency of mutations of the IDH2 gene was 5.9%; the variants included R172K and R140Q. The mean survival time in patients without IDH1 gene mutations was 173.15 days (120.20–226.10), while the mean survival time for patients with mutations was 54.95 days (9.7–100.18), p = 0.001.

Conclusion

The frequency of IDH1 and IDH2 gene mutations in the sample was similar to that reported in other studies. The analysis of these mutations in AML patients is of great importance as a prognostic factor due to their impact on survival and their use as potential therapeutic targets or as targets of inhibitors of IDH1(Ivosidenib, Tibsovo) and IDH2 (Enasidenib, Idhifa).

Gene mutation profile and risk stratification in AML1‑ETO‑positive acute myeloid leukemia based on next‑generation sequencing

Gene mutations play an important role in the development and progression of AML1-ETO-positive acute myeloid leukemia (AE-AML). Nevertheless, the gene mutation profile in this subtype of leukemia remains unclear. In addition, the clinical and prognostic effects of different mutant genes may be underestimated. In the present study, gene sequencing was conducted at diagnosis and relapse with next-generation sequencing (NGS) in 64 patients with newly diagnosed AE-AML, and 44/64 (68.8%) patients were found to present with a median of 2 (1–10) recurrent mutations at diagnosis and 6/11 (54.5%) cases were found to present with genetic alterations at relapse. c-KIT mutation was the most common in this cohort, with an incidence of 27/64 (42.2%) at diagnosis, followed by ASXL1 (n=10, 15.6%), MET (n=8, 12.5%), MLH1 (n=6, 9.4%), TET2 (n=5, 7.8%), and FBXW7, TP53 and DNMT3A (n=5, 7.8%). Survival analysis showed that c-KIT (exon 8, 17) but not exon 10 adversely affected survival. In addition, ASXL1 and TP53 were poor impact factors for recurrence-free survival (RFS) (P<0.05), and ASXL1, MET, FBXW7 and TP53 had a negative impact on overall survival (OS) (P<0.05). Multivariate analysis showed that c-KIT (exon 8, 17) [RFS: hazard ratio (HR) 3.36, 95% confidence interval (CI) 1.54–7.34, P=0.002; OS: HR 2.84, 95% CI 1.20–6.71, P=0.018] and ASXL1 mutations (RFS: HR 3.13, 95% CI 1.34–7.32, P=0.009; OS: HR 3.94, 95% CI 1.62–9.61, P=0.003) were independent adverse factors for survival. Further, co-mutation of these two genes showed even worse effect on disease outcome. Collectively, additional gene mutations play critical role in AE-AML. C-KIT and ASXL1 mutations are the two most common mutations in this subtype of leukemia. C-KIT (exon 8, 17) but not exon 10, and also the ASXL1 mutation poorly affect the disease outcome of this disease.

MicroRNA-425 upregulation indicates better prognosis in younger acute myeloid leukemia patients undergoing chemotherapy

The aim of the present study was to investigate whether the expression levels of microRNA-425 (miR-425) were associated with the prognosis of acute myeloid leukemia (AML) in patients treated with chemotherapy or allogeneic hematopoietic stem cell transplantation (allo-HSCT). A total of 162 AML patients were enrolled and divided into chemotherapy and allo-HSCT groups. Next, the overall survival (OS) and event-free survival (EFS) were compared between patients with high and low miR-425 expression in each of the treatment groups. In the chemotherapy group, high miR-425 expression was favorable for EFS (P=0.001) and OS (P=0.001) in younger patients (<60 years), whereas it had no effect on EFS and OS in older patients (≥60 years). In the allo-HSCT group, there was no association between miR-425 expression levels and clinical outcomes. Further analyses suggested that in the low miR-425 expression group, EFS and OS were longer in patients treated with allo-HSCT as compared with those treated with chemotherapy (both P<0.001), whereas no significant differences were observed in the high miR-425 expression group. In conclusion, the current data indicated that miR-425 is an independent favorable prognostic factor for younger AML patients undergoing chemotherapy, and its use may facilitate clinical decision-making in selecting treatment for AML patients. Patients with low miR-425 expression may benefit from allo-HSCT, whereas allo-HSCT did not appear to be beneficial in patients with high miR-425 expression.

Homoharringtonine exhibits potent anti-tumor effect and modulates DNA epigenome in acute myeloid leukemia by targeting SP1/TET1/5hmC

Homoharringtonine, a plant alkaloid, has been reported to suppress protein synthesis and has been approved by the US Food and Drug Administration for the treatment of chronic myeloid leukemia. Here we show that in acute myeloid leukemia (AML), homoharringtonine potently inhibits cell growth/viability and induces cell cycle arrest and apoptosis, significantly inhibits disease progression in vivo, and substantially prolongs survival of mice bearing murine or human AML. Strikingly, homoharringtonine treatment dramatically decreases global DNA 5-hydroxymethylcytosine abundance through targeting the SP1/TET1 axis, and TET1 depletion mimics homoharringtonine’s therapeutic effects in AML. Our further 5hmC-seq and RNA-seq analyses, followed by a series of validation and functional studies, suggest that FLT3 is a critical down-stream target of homoharringtonine/SP1/TET1/5hmC signaling, and suppression of FLT3 and its downstream targets (e.g. MYC) contributes to the high sensitivity of FLT3-mutated AML cells to homoharringtonine. Collectively, our studies uncover a previously unappreciated DNA epigenome-related mechanism underlying the potent antileukemic effect of homoharringtonine, which involves suppression of the SP1/TET1/5hmC/FLT3/MYC signaling pathways in AML. Our work also highlights the particular promise of clinical application of homoharringtonine to treat human AML with FLT3 mutations, which accounts for more than 30% of total cases of AML.

Epigenetic Therapy in a Patient With Down Syndrome and Refractory Acute Myeloid Leukemia

Acute myeloid leukemia (AML) associated with Down syndrome (DS-AML) is a unique entity of AML with superior treatment response and overall survival compared with children with non-DS-AML. Despite good outcomes in DS-AML, those who relapse or have refractory disease have poor survival. Successful treatment of these patients is challenged by increased incidence of treatment-related toxicities often encountered with high-dose chemotherapy. Here we report the experience of epigenetic modifying agents (decitabine and vorinostat) followed by fludarabine, cytarabine, and granulocyte colony stimulating growth factor for a child with refractory DS-AML. This combination was well tolerated and resulted in a brief clinical response.

Influence of diet and metabolism on hematopoietic stem cells and leukemia development following ionizing radiation exposure

PURPOSE

The review aims to discuss the prominence of dietary and metabolic regulators in maintaining hematopoietic stem cell (HSC) function, long-term self-renewal, and differentiation.

RESULTS

Most adult stem cells are preserved in a quiescent, nonmotile state in vivo which acts as a "protective state" for stem cells to reduce endogenous stress provoked by DNA replication and cellular respiration as well as exogenous environmental stress. The dynamic balance between quiescence, self-renewal and differentiation is critical for supporting a functional blood system throughout life of an organism. Stress-conditions, for example ionizing radiation exposure can trigger the blood forming HSCs to proliferate and migrate through extramedullary tissues to expand the number of HSCs and increase hematopoiesis. In addition, a wealth of investigation validated that deregulation of this balance plays a critical pathogenic role in various different hematopoietic diseases including the leukemia development.

CONCLUSION

The review summarizes the current knowledge on how alterations in dietary and metabolic factors could alter the risk of leukemia development following ionizing radiation exposure by inhibiting or even reversing the leukemic progression. Understanding the influence of diet, metabolism, and epigenetics on radiation-induced leukemogenesis may lead to the development of practical interventions to reduce the risk in exposed populations.

STK3 is a therapeutic target for a subset of acute myeloid leukemias

Acute myeloid leukemia (AML) is characterized by uncontrolled proliferation and accumulation of immature myeloblasts, which impair normal hematopoiesis. While this definition categorizes the disease into a distinctive group, the large number of different genetic and epigenetic alterations actually suggests that AML is not a single disease, but a plethora of malignancies. Still, most AML patients are not treated with targeted medication but rather by uniform approaches such as chemotherapy. The identification of novel treatment options likely requires the identification of cancer cell vulnerabilities that take into account the different genetic and epigenetic make-up of the individual tumors. Here we show that STK3 depletion by knock-down, knock-out or chemical inhibition results in apoptotic cells death in some but not all AML cell lines and primary cells tested. This effect is mediated by a premature activation of cyclin dependent kinase 1 (CDK1) in presence of elevated cyclin B1 levels. The anti-leukemic effects seen in both bulk and progenitor AML cells suggests that STK3 might be a promising target in a subset of AML patients.

5-Hydroxymethylcytosine correlates with epigenetic regulatory mutations, but may not have prognostic value in predicting survival in normal karyotype acute myeloid leukemia

Stem cells display remarkably high levels of 5-hydroxymethylcytosine (5hmC). Both TET2 and IDH1/2 mutations can impair the production of 5hmC, thus decreasing 5hmC levels. TET2 or IDH1/2 mutations are commonly observed in acute myeloid leukemia (AML). However, the implications of 5hmC on survival in normal karyotype AML patients have not been fully evaluated. The 5hmC levels were analyzed in 375 patients using ELISA. The levels of 5hmC in DNA samples were converted to a log scale for the analysis and correlations with TET2 and/or IDH1/2 mutations were evaluated. The median 5hmC level was 0.065% (range 0.001–0.999). Mutation rates were 13.1% for TET2^mut, 6.7% for IDH1^mut, and 13.9% for IDH2^mut. The prevalence of TET2 and/or IDH1/2 was 33.1% (124/375). TET2 and IDH1/2 mutated patients had significantly lower levels of log(5hmC) compared with patients without TET2 or IDH1/2 mutations (p<0.001). With a median follow-up of 55.5 months (range, 0.7–179.8), there was no significant difference in overall survival, event-free survival, and relapse risk according to TET2^mut or IDH1/2^mut (all, p>0.05). To identify its prognostic value, we sub-classified the levels of 5hmC into tertiles for 5hmC values. However, there was no significant association between the categories of 5hmC levels and survival or relapse risk (all p>0.05). Patients with TET2 or IDH1/2 mutations had lower levels of 5hmC. The 5hmC levels may not be predictive of survival in patients with normal karyotype AML.

Acute Myeloid Leukemia-Genetic Alterations and Their Clinical Prognosis

Acute myeloid leukemia (AML) is a group of hematological diseases, phenotypic and genetically heterogeneous, characterized by abnormal accumulation of blast cells in the bone marrows and peripheral blood. Its incidence rate is approximately 1.5 per 100,000 in infants younger than 1 year of age and 25 per 100,000 persons in octogenarians. Traditionally, cytogenetic markers are used to stratify patients in three risk categories: favorable, intermediate and unfavorable. However, the forecast stratification and the treatment decision for patients with normal karyotype shows difficulties due to the high clinical heterogeneity. The identification of several genetic mutations additional to classical molecular markers has been useful in identifying new entities. Nowadays, many different mutations and epigenetic aberrations have been implicated in the diagnostic, prognostic and treatment of AML. This review is focused on describing the most important molecular markers with implications for clinical practice.

RASSF1A hypermethylation is associated with ASXL1 mutation and indicates an adverse outcome in non-M3 acute myeloid leukemia

Objective

The purpose of this study was to evaluate the frequency of RASSF1A hypermethylation in patients with acute myeloid leukemia (AML), in an attempt to modify the current molecular model for disease prognosis.

Materials and methods

Aberrant RASSF1A promoter methylation levels were assessed in 226 newly diagnosed non-M3 AML patients and 30 apparently healthy controls, by quantitative methylation-specific polymerase chain reaction. Meanwhile, RASSF1A mRNA levels were detected by real-time quantitative polymerase chain reaction. Furthermore, hematological characteristics, cytogenetic abnormalities, and genetic aberrations were assessed. Finally, associations of RASSF1A hypermethylation with clinical outcomes were evaluated.

Results

RASSF1A hypermethylation was observed in 23.0% of patients with non-M3 AML (52/226), but not in controls. Meanwhile, hypermethylation of the RASSF1A promoter was significantly associated with ASXL1 mutation. Furthermore, the log-rank test revealed that RASSF1A hypermethylation indicated decreased relapse-free survival (RFS) and overall survival (OS) in patients with non-M3 AML (P=0.012 and P=0.014, respectively). In multivariate analysis, RASSF1A hypermethylation was an independent prognostic factor for RFS (P=0.040), but not for OS (P=0.060).

Conclusion

Hypermethylation of the RASSF1A promoter is associated with ASXL1 mutation in non-M3 AML patients, likely indicating poor outcome. These findings provide a molecular basis for stratified diagnosis and prognostic evaluation.

Semi-Quantitative Mass Spectrometry in AML Cells Identifies New Non-Genomic Targets of the EZH2 Methyltransferase

Alterations to the gene encoding the EZH2 (KMT6A) methyltransferase, including both gain-of-function and loss-of-function, have been linked to a variety of haematological malignancies and solid tumours, suggesting a complex, context-dependent role of this methyltransferase. The successful implementation of molecularly targeted therapies against EZH2 requires a greater understanding of the potential mechanisms by which EZH2 contributes to cancer. One aspect of this effort is the mapping of EZH2 partner proteins and cellular targets. To this end we performed affinity-purification mass spectrometry in the FAB-M2 HL-60 acute myeloid leukaemia (AML) cell line before and after all-trans retinoic acid-induced differentiation. These studies identified new EZH2 interaction partners and potential non-histone substrates for EZH2-mediated methylation. Our results suggest that EZH2 is involved in the regulation of translation through interactions with a number of RNA binding proteins and by methylating key components of protein synthesis such as eEF1A1. Given that deregulated mRNA translation is a frequent feature of cancer and that eEF1A1 is highly expressed in many human tumours, these findings present new possibilities for the therapeutic targeting of EZH2 in AML.

Epigenetically induced ectopic expression of UNCX impairs the proliferation and differentiation of myeloid cells

We here describe a leukemogenic role of the homeobox gene UNCX, activated by epigenetic modifications in acute myeloid leukemia (AML). We found the ectopic activation of UNCX in a leukemia patient harboring a t(7;10)(p22;p14) translocation, in 22 of 61 of additional cases [a total of 23 positive patients out of 62 (37.1%)], and in 6 of 75 (8%) of AML cell lines. UNCX is embedded within a low-methylation region (canyon) and encodes for a transcription factor involved in somitogenesis and neurogenesis, with specific expression in the eye, brain, and kidney. UNCX expression turned out to be associated, and significantly correlated, with DNA methylation increase at its canyon borders based on data in our patients and in archived data of patients from The Cancer Genome Atlas. UNCX-positive and -negative patients displayed significant differences in their gene expression profiles. An enrichment of genes involved in cell proliferation and differentiation, such as MAP2K1 and CCNA1, was revealed. Similar results were obtained in UNCX-transduced CD34⁺ cells, associated with low proliferation and differentiation arrest. Accordingly, we showed that UNCX expression characterizes leukemia cells at their early stage of differentiation, mainly M2 and M3 subtypes carrying wild-type NPM1. We also observed that UNCX expression significantly associates with an increased frequency of acute promyelocytic leukemia with PML-RARA and AML with t(8;21)(q22;q22.1); RUNX1-RUNX1T1 classes, according to the World Health Organization disease classification. In summary, our findings suggest a novel leukemogenic role of UNCX, associated with epigenetic modifications and with impaired cell proliferation and differentiation in AML.

Molecular Mutations and Their Cooccurrences in Cytogenetically Normal Acute Myeloid Leukemia

Adult acute myeloid leukemia (AML) clinically is a disparate disease that requires intensive treatments ranging from chemotherapy alone to allogeneic hematopoietic cell transplantation (allo-HCT). Historically, cytogenetic analysis has been a useful prognostic tool to classify patients into favorable, intermediate, and unfavorable prognostic risk groups. However, the intermediate-risk group, consisting predominantly of cytogenetically normal AML (CN-AML), itself exhibits diverse clinical outcomes and requires further characterization to allow for more optimal treatment decision-making. The recent advances in clinical genomics have led to the recategorization of CN-AML into favorable or unfavorable subgroups. The relapsing nature of AML is thought to be due to clonal heterogeneity that includes founder or driver mutations present in the leukemic stem cell population. In this article, we summarize the clinical outcomes of relevant molecular mutations and their cooccurrences in CN-AML, including NPM1, FLT3^ITD, DNMT3A, NRAS, TET2, RUNX1, MLL^PTD, ASXL1, BCOR, PHF6, CEBPA^biallelic, IDH1, IDH2^R140, and IDH2^R170, with an emphasis on their relevance to the leukemic stem cell compartment. We have reviewed the available literature and TCGA AML databases (2013) to highlight the potential role of stem cell regulating factor mutations on outcome within newly defined AML molecular subgroups.

miR-155 expression and correlation with clinical outcome in pediatric AML: A report from Children's Oncology Group

BACKGROUND

Aberrant expression of microRNA-155 (miR-155) has been implicated in acute myeloid leukemia (AML) and associated with clinical outcome.

PROCEDURE

We evaluated miR-155 expression in 198 children with normal karyotype AML (NK-AML) enrolled in Children's Oncology Group (COG) AML trial AAML0531 and correlated miR-155 expression levels with disease characteristics and clinical outcome. Patients were divided into quartiles (Q1-Q4) based on miR-155 expression level, and disease characteristics were then evaluated and correlated with miR-155 expression.

RESULTS

MiR-155 expression varied over 4-log10-fold range relative to its expression in normal marrow with a median expression level of 0.825 (range 0.043-25.630) for the entire study cohort. Increasing miR-155 expression was highly associated with the presence of FLT3/ITD mutations (P < 0.001) and high-risk disease (P < 0.001) and inversely associated with standard-risk (P = 0.008) and low-risk disease (P = 0.041). Patients with highest miR-155 expression had a complete remission (CR) rate of 46% compared with 82% in low expressers (P < 0.001) with a correspondingly lower event-free (EFS) and overall survival (OS) (P < 0.001 and P = 0.002, respectively). In a multivariate model that included molecular risk factors, high miR-155 expression remained a significant independent predictor of OS (P = 0.022) and EFS (0.019).

CONCLUSIONS

High miR-155 expression is an adverse prognostic factor in pediatric NK-AML patients. Specifically, high miR-155 expression not only correlates with FLT3/ITD mutation status and high-risk disease but it is also an independent predictor of worse EFS and OS.

Isocitrate dehydrogenase mutations in myeloid malignancies

Alterations to genes involved in cellular metabolism and epigenetic regulation are implicated in the pathogenesis of myeloid malignancies. Recurring mutations in isocitrate dehydrogenase (IDH) genes are detected in approximately 20% of adult patients with acute myeloid leukemia (AML) and 5% of adults with myelodysplastic syndromes (MDS). IDH proteins are homodimeric enzymes involved in diverse cellular processes, including adaptation to hypoxia, histone demethylation and DNA modification. The IDH2 protein is localized in the mitochondria and is a critical component of the tricarboxylic acid (also called the ‘citric acid' or Krebs) cycle. Both IDH2 and IDH1 (localized in the cytoplasm) proteins catalyze the oxidative decarboxylation of isocitrate to α-ketoglutarate (α-KG). Mutant IDH enzymes have neomorphic activity and catalyze reduction of α-KG to the (R) enantiomer of 2-hydroxyglutarate, which is associated with DNA and histone hypermethylation, altered gene expression and blocked differentiation of hematopoietic progenitor cells. The prognostic significance of mutant IDH (mIDH) is controversial but appears to be influenced by co-mutational status and the specific location of the mutation (IDH1-R132, IDH2-R140, IDH2-R172). Treatments specifically or indirectly targeted to mIDH are currently under clinical investigation; these therapies have been generally well tolerated and, when used as single agents, have shown promise for inducing responses in some mIDH patients when used as first-line treatment or in relapsed or refractory AML or MDS. Use of mIDH inhibitors in combination with drugs with non-overlapping mechanisms of action is especially promising, as such regimens may address the clonal heterogeneity and the multifactorial pathogenic processes involved in mIDH myeloid malignancies. Advances in mutational analysis have made testing more rapid and convenient, and less expensive; such testing should become part of routine diagnostic workup and repeated at relapse to identify patients who may benefit from treatments that target mIDH.

Epigenetics in Cancer: A Hematological Perspective

For several decades, we have known that epigenetic regulation is disrupted in cancer. Recently, an increasing body of data suggests epigenetics might be an intersection of current cancer research trends: next generation sequencing, immunology, metabolomics, and cell aging. The new emphasis on epigenetics is also related to the increasing production of drugs capable of interfering with epigenetic mechanisms and able to trigger clinical responses in even advanced phase patients. In this review, we will use myeloid malignancies as proof of concept examples of how epigenetic mechanisms can trigger or promote oncogenesis. We will also show how epigenetic mechanisms are related to genetic aberrations, and how they affect other systems, like immune response. Finally, we will show how we can try to influence the fate of cancer cells with epigenetic therapy.

Association of DNA methyltransferase polymorphisms with susceptibility to primary gouty arthritis

Gouty arthritis is the most common type of inflammatory and immune disease, and the prevalence and incidence of gout increases annually. Genetic variations in the DNA methyltransferases (DNMTs) gene have not, to the best of our knowledge, been reported to influence gene expression and to participate in the pathogenesis of gout. The aim of the present study was to investigate whether the DNMT1, DNMT3A and DNMT3B polymorphisms contribute to gout susceptibility. These polymorphisms were screened for in 336 gout patients and 306 healthy control subjects (from a South China population) for association with gout. The distribution frequencies of DNMT1 rs2228611 AA genotype (P=0.007) and A allele (P=0.002; odds ratio=1.508, 95% confidence interval=1.158-1.964) were found to be significantly increased in the gout patients when compared with those in the healthy control subjects. The rs1550117 in DNMT3A and rs2424913 in DNMT3B exhibited no significant associations with gout susceptibility between the patients and control subjects. These results demonstrated that the DNMT1 rs2228611 polymorphism may be involved in the pathogenesis of gout, while DNMT3A rs1550117 and DNMT3B rs2424913 did not show any obvious significance in the current study; thus, may not be used as risk factors to predict the susceptibility to gout. However, further studies are required to investigate the functions and regulatory mechanism of the polymorphisms of DNMTs in gout.

Comprehensive mutational profiling of core binding factor acute myeloid leukemia

Acute myeloid leukemia (AML) with t(8;21) or inv(16) have been recognized as unique entities within AML and are usually reported together as core binding factor AML (CBF-AML). However, there is considerable clinical and biological heterogeneity within this group of diseases, and relapse incidence reaches up to 40%. Moreover, translocations involving CBFs are not sufficient to induce AML on its own and the full spectrum of mutations coexisting with CBF translocations has not been elucidated. To address these issues, we performed extensive mutational analysis by high-throughput sequencing in 215 patients with CBF-AML enrolled in the Phase 3 Trial of Systematic Versus Response-adapted Timed-Sequential Induction in Patients With Core Binding Factor Acute Myeloid Leukemia and Treating Patients with Childhood Acute Myeloid Leukemia with Interleukin-2 trials (age, 1-60 years). Mutations in genes activating tyrosine kinase signaling (including KIT, N/KRAS, and FLT3) were frequent in both subtypes of CBF-AML. In contrast, mutations in genes that regulate chromatin conformation or encode members of the cohesin complex were observed with high frequencies in t(8;21) AML (42% and 18%, respectively), whereas they were nearly absent in inv(16) AML. High KIT mutant allele ratios defined a group of t(8;21) AML patients with poor prognosis, whereas high N/KRAS mutant allele ratios were associated with the lack of KIT or FLT3 mutations and a favorable outcome. In addition, mutations in epigenetic modifying or cohesin genes were associated with a poor prognosis in patients with tyrosine kinase pathway mutations, suggesting synergic cooperation between these events. These data suggest that diverse cooperating mutations may influence CBF-AML pathophysiology as well as clinical behavior and point to potential unique pathogenesis of t(8;21) vs inv(16) AML.

CDKN2B, SLC19A3 and DLEC1 promoter methylation alterations in the bone marrow of patients with acute myeloid leukemia during chemotherapy

Previous studies have demonstrated that promoter hypermethylation of tumor suppressor genes contributes to the occurrence and development of acute myeloid leukemia (AML). However, the association of DNA methylation with chemotherapeutic outcomes remains unknown. In the present study, 15 patients with AML were recruited, and the promoter methylation status of cyclin-dependent kinase inhibitor 2B (CDKN2B), solute carrier family 19 member 3 (SLC19A3) and deleted in lung and esophageal cancer 1 (DLEC1) genes was examined prior to and following various chemotherapeutic regimens in order to identify any alterations. The results suggested that chemotherapy-induced hypermethylation of CDKN2B and DLEC1 may be specific to males and females, respectively, and that there were no alterations in SLC19A3 methylation following chemotherapy. These results may provide an improved understanding of gene methylation to guide the development of an individualized chemotherapy for AML. Due to the complexity of AML and the wide range of treatment types, future studies with a larger sample size are required in order to verify the results of the present investigation.

High expression of dual-specificity phosphatase 5 pseudogene 1 (DUSP5P1) is associated with poor prognosis in acute myeloid leukemia

The purpose of this study was to investigate the expression status of Dual-Specificity Phosphatase 5 Pseudogene 1 (DUSP5P1) and its clinical relevance in patients with acute myeloid leukemia (AML). Real-time quantitative PCR (RQ-PCR) was performed to detect the status of DUSP5P1 expression in 89 patients with de novo AML and 24 normal controls. The level of DUSP5P1 expression was significantly up-regulated in AML compared to controls (P=0.031). The patients with high expression of DUSP5P1 had higher percentage of blasts in bone marrow (BM) than those without high expression (P=0.027). The occurrence rate of DUSP5P1 high expression was significantly higher in M1 (2/8, 25%) and M2 subtypes (9/33, 27%) than in M3 subtype (0/17, 0%) (P=0.034). At the same time, the frequency of DUSP5P1 high expression in patients with intermediate (13/53, 24%) and poor karyotypes (5/11, 45%) was significantly higher than that in patients with favorable karyotype (0/21, 0%) (P=0.003). Meanwhile, DUSP5P1 high-expressed patients had significantly shorter overall survival (OS) than those with low expression (median 4.5 vs. 10.5 months, respectively, P=0.038). Our findings indicated that high expression of DUSP5P1 may identify high-risk AML patients and is associated with poor prognosis in AML.

Novel angiogenin mutants with increased cytotoxicity enhance the depletion of pro-inflammatory macrophages and leukemia cells ex vivo

Immunotoxins are fusion proteins that combine a targeting component such as an antibody fragment or ligand with a cytotoxic effector component that induces apoptosis in specific cell populations displaying the corresponding antigen or receptor. Human cytolytic fusion proteins (hCFPs) are less immunogenic than conventional immunotoxins because they contain human pro-apoptotic enzymes as effectors. However, one drawback of hCFPs is that target cells can protect themselves by expressing endogenous inhibitor proteins. Inhibitor-resistant enzyme mutants that maintain their cytotoxic activity are therefore promising effector domain candidates. We recently developed potent variants of the human ribonuclease angiogenin (Ang) that were either more active than the wild-type enzyme or less susceptible to inhibition because of their lower affinity for the ribonuclease inhibitor RNH1. However, combining the mutations was unsuccessful because although the enzyme retained its higher activity, its susceptibility to RNH1 reverted to wild-type levels. We therefore used molecular dynamic simulations to determine, at the atomic level, why the affinity for RNH1 reverted, and we developed strategies based on the introduction of further mutations to once again reduce the affinity of Ang for RNH1 while retaining its enhanced activity. We were able to generate a novel Ang variant with remarkable in vitro cytotoxicity against HL-60 cells and pro-inflammatory macrophages. We also demonstrated the pro-apoptotic potential of Ang-based hCFPs on cells freshly isolated from leukemia patients.

Genomics-based Approach and Prognostic Stratification Significance of Gene Mutations in Intermediate-risk Acute Myeloid Leukemia

OBJECTIVE

Intermediate-risk acute myeloid leukemia (IR-AML), which accounts for a substantial number of AML cases, is highly heterogeneous. We systematically summarize the latest research progress on the significance of gene mutations for prognostic stratification of IR-AML.

DATA SOURCES

We conducted a systemic search from the PubMed database up to October, 2014 using various search terms and their combinations including IR-AML, gene mutations, mutational analysis, prognosis, risk stratification, next generation sequencing (NGS).

STUDY SELECTION

Clinical or basic research articles on NGS and the prognosis of gene mutations in IR-AML were included.

RESULTS

The advent of the era of whole-genome sequencing has led to the discovery of an increasing number of molecular genetics aberrations that involved in leukemogenesis, and some of them have been used for prognostic risk stratification. Several studies have consistently identified that some gene mutations have prognostic relevance, however, there are still many controversies for some genes because of lacking sufficient evidence. In addition, tumor cells harbor hundreds of mutated genes and multiple mutations often coexist, therefore, single mutational analysis is not sufficient to make accurate prognostic predictions. The comprehensive analysis of multiple mutations based on sophisticated genomic technologies has raised increasing interest in recent years.

CONCLUSIONS

NGS represents a pioneering and helpful approach to prognostic risk stratification of IR-AML patients. Further large-scale studies for comprehensive molecular analysis are needed to provide guidance and a theoretical basis for IR-AML prognostic stratification and clinical management.

Downregulated Poly-C binding protein-1 is a novel predictor associated with poor prognosis in Acute Myeloid Leukemia

Background

Depletion of Poly-C binding protein-1(PCBP1) is implicated in various human malignancies. However, the underlying biological effect of PCBP1 in cancers, including acute myeloid leukemia (AML), still remains elusive. The purpose of this study was to examine the expression and clinical outcome of PCBP1in acute myeloid leukemia.

Methods

Bone marrow fluids of 88 newly diagnosed AML patients were sampled, and the PCBP1 mRNA expression level was evaluated using quantitative RT-PCR. The association between PCBP1 expression and clinicopathological features or the survival status of the patients was assessed by Chi-square test and Kaplan-Meier method.

Results

Comparing newly diagnosed AML patients to normal healthy donors, PCBP1 expression was significantly decreased in AML patients (P < 0.001). Conversely, PCBP1 expression had accordingly recovered back to normal in patients with complete remission (P < 0.001). Clinical feature analyses showed that PCBP1 expression was negatively correlated with white blood cell count (P = 0.024). In addition, patients with low PCBP1 expression had poor disease-free survival (11.8 % vs. 45.3 %; P = 0.01) and overall survival (18.2 % vs. 42.4 %; P = 0.032), respectively.

Conclusions

Taken together, our results showed for the first time that expression of PCBP1 was down-regulated in newly diagnosed AML patients and might be an independent prognostic marker in AML and should to be further investigated.

Drugging the unfolded protein response in acute leukemias

The unfolded protein response (UPR), an endoplasmic reticulum (ER) stress-induced signaling cascade, is mediated by three major stress sensors IRE-1α, PERK, and ATF6α. Studies described the UPR as a critical network in selection, adaptation, and survival of cancer cells. While previous reviews focused mainly on solid cancer cells, in this review, we summarize the recent findings focusing on acute leukemias. We take into account the impact of the underlying genetic alterations of acute leukemia cells, the leukemia stem cell pool, and provide an outline on the current genetic, clinical, and therapeutic findings. Furthermore, we shed light on the important oncogene-specific regulation of individual UPR signaling branches and the therapeutic relevance of this information to answer the question if the UPR could be an attractive novel target in acute leukemias.

Targeting cell cycle regulators in hematologic malignancies

Hematologic malignancies represent the fourth most frequently diagnosed cancer in economically developed countries. In hematologic malignancies normal hematopoiesis is interrupted by uncontrolled growth of a genetically altered stem or progenitor cell (HSPC) that maintains its ability of self-renewal. Cyclin-dependent kinases (CDKs) not only regulate the mammalian cell cycle, but also influence other vital cellular processes, such as stem cell renewal, differentiation, transcription, epigenetic regulation, apoptosis, and DNA repair. Chromosomal translocations, amplification, overexpression and altered CDK activities have been described in different types of human cancer, which have made them attractive targets for pharmacological inhibition. Mouse models deficient for one or more CDKs have significantly contributed to our current understanding of the physiological functions of CDKs, as well as their roles in human cancer. The present review focuses on selected cell cycle kinases with recent emerging key functions in hematopoiesis and in hematopoietic malignancies, such as CDK6 and its role in MLL-rearranged leukemia and acute lymphocytic leukemia, CDK1 and its regulator WEE-1 in acute myeloid leukemia (AML), and cyclin C/CDK8/CDK19 complexes in T-cell acute lymphocytic leukemia. The knowledge gained from gene knockout experiments in mice of these kinases is also summarized. An overview of compounds targeting these kinases, which are currently in clinical development in various solid tumors and hematopoietic malignances, is presented. These include the CDK4/CDK6 inhibitors (palbociclib, LEE011, LY2835219), pan-CDK inhibitors that target CDK1 (dinaciclib, flavopiridol, AT7519, TG02, P276-00, terampeprocol and RGB 286638) as well as the WEE-1 kinase inhibitor, MK-1775. The advantage of combination therapy of cell cycle inhibitors with conventional chemotherapeutic agents used in the treatment of AML, such as cytarabine, is discussed.

Epigenetic Therapy in Acute Myeloid Leukemia: Current and Future Directions

Epigenetic modifications affect gene expression without changes in the actual DNA sequence. Two of the most important mechanisms include DNA methylation and histone tail modifications (especially acetylation and methylation). Epigenetic modulation is a part of normal physiologic development; its dysregulation is an important mechanism of pathogenesis of some cancers, including acute myeloid leukemia (AML). Despite significant progress in understanding the pathogenesis of AML, therapeutic options remain quite limited. Technological advances have facilitated understanding of aberrant DNA methylation and histone methylation/acetylation as key elements in the development of AML and uncovered several recurrent mutations in genes important for epigenetic regulation. However, much remains to be learned about how to exploit this knowledge for epigenetic therapeutic targeting. Currently, no epigenetic therapy is approved for the treatment of AML, although two DNA methyltransferase inhibitors (azacitidine and decitabine) are commonly used in clinical practice. Among the other epigenetic modifiers undergoing research in AML, the histone deacetylase inhibitors are the most studied. Other promising drugs, such as inhibitors of histone methylation (eg, EZH2 and DOT1L inhibitors), inhibitors of histone demethylases (eg, LSD1 inhibitors), inhibitors of bromodomain-containing epigenetic "reader" BET proteins, and inhibitors of mutant isocitrate dehydrogenases, are at early stages of clinical evaluation.