Mutational landscape of AML with normal cytogenetics: biological and clinical implications

SIRT2 is an unfavorable prognostic biomarker in patients with acute myeloid leukemia

SIRT2 is a member of the NAD+ dependent deacetylases. In this study, the associations between SIRT2 expression and molecular and clinical characteristics of patients with acute myeloid leukemia (AML) were evaluated by data from The Cancer Genome Atlas. SIRT2 was overexpressed in the intermediate- and poor-risk groups of patients, compared to the favorable-risk group of patients (P = 0.002 and 0.004, respectively). High SIRT2 expression was associated with significantly shorter overall survival (OS; P = 0.0005) and event-free survival (EFS; P = 0.0002) than low SIRT2 expressio in a cohort of 167 patients with AML. Multivariate analyses revealed that high SIRT2 expression was associated with shorter OS (P = 0.031) and EFS (P = 0.020). Gene-expression profiling showed 259 differential expressed genes including CD4, CD14 and IL10. Gene sets like MAPK signaling pathway, VEGF signaling pathway and acute myeloid leukemia were upregulated in SIRT2^high patients. We also found different methylation patterns in these two groups. OS and EFS of SIRT2^high patients who did not undergo transplantation were significantly shorter than those of SIRT2^low patients (P = 0.0120 and P = 0.0107, respectively). Taken together, these findings suggest that high SIRT2 expression is a novel and unfavorable prognostic biomarker for AML risk-stratification.

Simultaneous detection of mutations and copy number variation of NPM1 in the acute myeloid leukemia using multiplex ligation-dependent probe amplification

The NPM1 gene encodes nucleophosmin, a protein involved in multiple cell functions and carcinogenesis. Mutation of the NPM1 gene, causing delocalization of the protein, is the most frequent genetic lesion in acute myeloid leukemia (AML); it is considered a founder event in AML pathogenesis and serves as a favorable prognostic marker. Moreover, in solid tumors and some leukemia cell lines, overexpression of the NPM1 gene is commonly observed. Therefore, the purpose of this study was to develop a new method for the detection of NPM1 mutations and the simultaneous analysis of copy number alterations (CNAs), which may underlie NPM1 gene expression deregulation. To address both of the issues, we applied a strategy based on multiplex ligation-dependent probe amplification (MLPA). A designed NPM1mut+ assay enables the detection of three of the most frequent NPM1 mutations: A, B and D. The accuracy of the assay was tested using a group of 83 samples from Polish patients with AML and other blood-proliferative disorders. To verify the results, we employed traditional Sanger sequencing and next-generation transcriptome sequencing. With the use of the NPM1mut+ assay, we detected mutations A, D and B in 14, 1 and 0 of the analyzed samples, respectively. All of these mutations were confirmed by complementary sequencing approaches, proving the 100% specificity and sensitivity of the proposed test. The performed sequencing analysis allowed the identification of two additional rare mutations (I and ZE). All of the mutations were identified exclusively in AML cases, accounting for 25% of those cases. We did not observe any CNAs (amplifications) of the NPM1 gene in the studied samples, either with or without the mutation. The presented method is simple, reliable and cost-effective. It can be easily introduced into clinical practice or developed to target both less-frequent mutations in the NPM1 gene and other cancer-related genes.

IL-27 Promotes Proliferation of Human Leukemic Cell Lines Through the MAPK/ERK Signaling Pathway and Suppresses Sensitivity to Chemotherapeutic Drugs

IL-27 is a pleiotropic cytokine of the IL-6/IL-12 family with diverse biological functions. Previous in vivo studies have suggested the antitumor activities of IL-27 in animal models, whereas clinical observations indicate the link of IL-27 in tumor progression. IL-27 has recently been shown to cause inhibition of proliferation on primary leukemic cells from pediatric patients, but information on its role in human leukemic cell lines is limited. In the present study, we investigated the ability of IL-27 to regulate cell growth and survival of various human leukemic cell lines. Our results showed that in human leukemic cell lines coexpressing both IL-27R chains, IL-27Rα and gp130, IL-27 did not inhibit cell growth, but caused dose-dependent proliferation of the acute myeloid leukemic cell line, OCI-AML5, and the erythroleukemic cell lines, TF-1, UT-7, and UT-7/EPO. Consistent with this, IL-27 promoted cell survival and reduced TNF-α-induced apoptosis of the leukemic cell lines. IL-27 also decreased the responsiveness of the leukemic cells to chemotherapeutic drugs, cytarabine and daunorubicin. We observed that IL-27 induced the activation of STAT1/3 and ERK1/2 in the leukemic cells. Growth stimulation by IL-27 was suppressed by the specific MEK inhibitor, U0126, indicating that IL-27-induced cell proliferation is mainly mediated through the activation of the MAPK/ERK signaling pathway. The present study is the first demonstration of the proliferative and antichemotherapeutic properties of IL-27 in human leukemic cell lines, suggesting that IL-27 can play an unfavorable role in tumor growth and can be an important determinant in the chemoresponsiveness of certain subtypes of human leukemia.

Molecular landscape in acute myeloid leukemia: where do we stand in 2016

Acute myeloid leukemia (AML) is a clonal disorder characterized by the accumulation of complex genomic alterations that define the disease pathophysiology and overall outcome. Recent advances in sequencing technologies have described the molecular landscape of AML and identified several somatic alterations that impact overall survival. Despite all these advancement, several challenges remain in translating this information into effective therapy. Herein we will review the molecular landscape of AML and discuss the impact of the most common somatic mutations on disease biology and outcome.

Transplant outcomes of the triple-negative NPM1/FLT3-ITD/CEBPA mutation subgroup are equivalent to those of the favourable ELN risk group, but significantly better than the intermediate-I risk group after allogeneic transplant in normal-karyotype AML

The prognostic significance of molecular mutations (FLT3-ITD, NPM1, and CEBPA mutations) was examined in patients with normal-karyotype acute myeloid leukaemia (NK-AML) after allogeneic haematopoietic cell transplantation (HCT). In total, 115 patients received allogeneic HCT for NK-AML and were evaluated for FLT3-ITD, NPM1, and CEBPA mutations in diagnostic samples and for long-term outcomes following HCT, retrospectively. The prevalences of FLT3-ITD(pos), NPM1 (mut), and CEBPA (dm) (double mutations) were 32.2, 43.5, and 24.6 %, respectively. The triple-negative group (NPM1 (wild)/FLT3-ITD(neg)/non-CEBPA (dm)) showed a similar transplant outcome to those in the favourable European LeukemiaNet (ELN) risk group for overall survival (OS) (60.9 vs. 63.7 %; p = 0.810), but a more favourable OS than others in the intermediate-I risk group (40.0 %; p = 0.034). Also, the triple-negative group showed a similar relapse rate at 5 years compared with those in the favourable risk group (9.7 vs. 15.5 %; p = 0.499), but a lower rate of relapse than the others in the intermediate-I risk group (15.5 vs. 48.6 %; p = 0.004). The 5-year relapse incidences were 4.0 % (NPM1 (mut)/FLT3-ITD(neg)), 14.7 % (CEBPA (dm)), 15.5 % (NPM1 (wild)/FLT3-ITD(neg)/non-CEBPA (dm)), 39.1 % (NPM1 (mut)/FLT3-ITD(pos)/non-CEBPA (dm)), and 66.7 % (NPM1 (wild)/FLT3-ITD(pos)/non-CEBPA (dm)). Thus, the triple-negative (NPM1 (wild)/FLT3-ITD(neg)/non-CEBPA (dm)) group showed favourable long-term outcomes after allogeneic HCT in NK-AML, similar to those of the favourable risk group by the ELN risk classification.

Impact of genomics in the clinical management of patients with cytogenetically normal acute myeloid leukemia

Acute myeloid leukemia (AML) is a clinically and molecularly heterogeneous disease. Cytogenetics and FISH have contributed to the stratification of AML patients into favorable, intermediate, and unfavorable risk categories. However, until recently, the prognostic stratification and treatment decision for the intermediate risk category, mostly comprising AML patients with normal cytogenetics (CN-AML), has been difficult due to the scarce knowledge of the molecular alterations underlying this large AML subgroup (which accounts for about 50% of all adult AML). During the past decade, the discovery of numerous mutations associated with CN-AML has resulted in significant advances in the AML field. Here, we review the biological characteristics of the most common mutations underlying CN-AML and outline their clinical impact in the following settings: (i) definition of new molecular leukemia entities in the WHO classification; (ii) risk stratification of CN-AML patients according to mutational profile; and (iii) monitoring of minimal residual disease by specific quantitative molecular assays.

The interplay of autophagy and β-Catenin signaling regulates differentiation in acute myeloid leukemia

The major feature of leukemic cells is an arrest of differentiation accompanied by highly active proliferation. In many subtypes of acute myeloid leukemia, these features are mediated by the aberrant Wnt/β-Catenin pathway. In our study, we established the lectin LecB as inducer of the differentiation of the acute myeloid leukemia cell line THP-1 and used it for the investigation of the involved processes. During differentiation, functional autophagy and low β-Catenin levels were essential. Corresponding to this, a high β-Catenin level stabilized proliferation and inhibited autophagy, resulting in low differentiation ability. Initiated by LecB, β-Catenin was degraded, autophagy became active and differentiation took place within hours. Remarkably, the reduction of β-Catenin sensitized THP-1 cells to the autophagy-stimulating mTOR inhibitors. As downmodulation of E-Cadherin was sufficient to significantly reduce LecB-mediated differentiation, we propose E-Cadherin as a crucial interaction partner in this signaling pathway. Upon LecB treatment, E-Cadherin colocalized with β-Catenin and thereby prevented the induction of β-Catenin target protein expression and proliferation. That way, our study provides for the first time a link between E-Cadherin, the aberrant Wnt/β-Catenin signaling, autophagy and differentiation in acute myeloid leukemia. Importantly, LecB was a valuable tool to elucidate the underlying molecular mechanisms of acute myeloid leukemia pathogenesis and may help to identify novel therapy approaches.

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.

Class III Receptor Tyrosine Kinases in Acute Leukemia - Biological Functions and Modern Laboratory Analysis

Acute myeloid leukemia (AML) is a complex disease caused by deregulation of multiple signaling pathways. Mutations in class III receptor tyrosine kinases (RTKs) have been implicated in alteration of cell signals concerning the growth and differentiation of leukemic cells. Point mutations, insertions, or deletions of RTKs as well as chromosomal translocations induce constitutive activation of the receptor, leading to uncontrolled proliferation of undifferentiated myeloid blasts. Aberrations can occur in all domains of RTKs causing either the ligand-independent activation or mimicking the activated conformation. The World Health Organization recommended including RTK mutations in the AML classification since their detection in routine laboratory diagnostics is a major factor for prognostic stratification of patients. Polymerase chain reaction (PCR)-based methods are well-validated for the detection of fms-related tyrosine kinase 3 (FLT3) mutations and can easily be applied for other RTKs. However, when methodological limitations are reached, accessory techniques can be applied. For a higher resolution and more quantitative approach compared to agarose gel electrophoresis, PCR fragments can be separated by capillary electrophoresis. Furthermore, high-resolution melting and denaturing high-pressure liquid chromatography are reliable presequencing screening methods that reduce the sample amount for Sanger sequencing. Because traditional DNA sequencing is time-consuming, next-generation sequencing (NGS) is an innovative modern possibility to analyze a high amount of samples simultaneously in a short period of time. At present, standardized procedures for NGS are not established, but when this barrier is resolved, it will provide a new platform for rapid and reliable laboratory diagnostic of RTK mutations in patients with AML. In this article, the biological and physiological role of RTK mutations in AML as well as possible laboratory methods for their detection will be reviewed.

Altered HLA Class I Profile Associated with Type A/D Nucleophosmin Mutation Points to Possible Anti-Nucleophosmin Immune Response in Acute Myeloid Leukemia

Nucleophosmin 1 (NPM1) mutations are frequently found in patients with acute myeloid leukemia (AML) and the newly generated sequences were suggested to induce immune response contributing to the relatively favorable outcome of patients in this AML subset. We hypothesized that if an efficient immune response against mutated nucleophosmin can be induced in vivo, the individuals expressing HLA alleles suitable for presenting NPM-derived peptides should be less prone to developing AML associated with NPM1 mutation. We thus compared HLA class I frequencies in a cohort of patients with mutated NPM1 (63 patients, NPMc+), a cohort of patients with wild-type NPM1 (94 patients, NPMwt) and in normal individuals (large datasets available from Allele Frequency Net Database). Several HLA allelic groups were found to be depleted in NPMc+ patients, but not in NPMwt compared to the normal distribution. The decrease was statistically significant for HLA B*07, B*18, and B*40. Furthermore, statistically significant advantage in the overall survival was found for patients with mutated NPM1 expressing at least one of the depleted allelic groups. The majority of the depleted alleles were predicted to bind potent NPM-derived immunopeptides and, importantly, these peptides were often located in the unmutated part of the protein. Our analysis suggests that individuals expressing specific HLA allelic groups are disposed to develop an efficient anti-AML immune response thanks to aberrant cytoplasmic localization of the mutated NPM protein.

Perspectives for therapeutic targeting of gene mutations in acute myeloid leukaemia with normal cytogenetics

The acute myeloid leukaemia (AML) genome contains more than 20 driver recurrent mutations. Here, we review the potential for therapeutic targeting of the most common mutations associated with normal cytogenetics AML, focusing on those affecting the FLT3, NPM1 and epigenetic modifier genes (DNMT3A, IDH1/2, TET2). As compared to early compounds, second generation FLT3 inhibitors are more specific and have better pharmacokinetics. They also show higher anti-leukaemic activity, leading to about 50% of composite complete remissions in refractory/relapsed FLT3-internal tandem duplication-mutated AML. However, rapid relapses invariably occur due to various mechanisms of resistance to FLT3 inhibitors. This issue and the best way for using FLT3 inhibitors in combination with other therapeutic modalities are discussed. Potential approaches for therapeutic targeting of NPM1-mutated AML include: (i) reverting the aberrant nuclear export of NPM1 mutant using exportin-1 inhibitors; (ii) disruption of the nucleolus with drugs blocking the oligomerization of wild-type nucleophosmin or inducing nucleolar stress; and (iii) immunotherapeutic targeting of highly expressed CD33 and IL3RA (CD123) antigens. Finally, we discuss the role of demethylating agents (decitabine and azacitidine) and IDH1/2 inhibitors in the treatment of AML patients carrying mutations of genes (DNMT3A, IDH1/2 and TET2) involved in the epigenetic regulation of transcription.

Molecular Genetic Markers in Acute Myeloid Leukemia

Genetics play an increasingly important role in the risk stratification and management of acute myeloid leukemia (AML) patients. Traditionally, AML classification and risk stratification relied on cytogenetic studies; however, molecular detection of gene mutations is playing an increasingly important role in classification, risk stratification, and management of AML. Molecular testing does not take the place of cytogenetic testing results, but plays a complementary role to help refine prognosis, especially within specific AML subgroups. With the exception of acute promyelocytic leukemia, AML therapy is not targeted but the intensity of therapy is driven by the prognostic subgroup. Many prognostic scoring systems classify patients into favorable, poor, or intermediate prognostic subgroups based on clinical and genetic features. Current standard of care combines cytogenetic results with targeted testing for mutations in FLT3, NPM1, CEBPA, and KIT to determine the prognostic subgroup. Other gene mutations have also been demonstrated to predict prognosis and may play a role in future risk stratification, although some of these have not been confirmed in multiple studies or established as standard of care. This paper will review the contribution of cytogenetic results to prognosis in AML and then will focus on molecular mutations that have a prognostic or possible therapeutic impact.

Mutational profiling of therapy-related myelodysplastic syndromes and acute myeloid leukemia by next generation sequencing, a comparison with de novo diseases

In this study we used a next generation sequencing-based approach to profile gene mutations in therapy-related myelodysplastic syndromes (t-MDS) and acute myeloid leukemia (t-AML); and compared these findings with de novo MDS/AML. Consecutive bone marrow samples of 498 patients, including 70 therapy-related (28 MDS and 42 AML) and 428 de novo (147 MDS and 281 AML) were analyzed using a modified-TruSeq Amplicon Cancer Panel (Illumina) covering mutation hotspots of 53 genes. Overall, mutation(s) were detected in 58.6% of t-MDS/AML and 56.8% of de novo MDS/AML. Of therapy-related cases, mutations were detected in 71.4% of t-AML versus 39.3% t-MDS (p=0.0127). TP53 was the most common mutated gene in t-MDS (35.7%) as well as t-AML (33.3%), significantly higher than de novo MDS (17.7%) (p=0.0410) and de novo AML (12.8%) (p=0.0020). t-AML showed more frequent PTPN11 but less NPM1 and FLT3 mutations than de novo AML. In summary, t-MDS/AML shows a mutation profile different from their de novo counterparts. TP53 mutations are highly and similarly prevalent in t-MDS and t-AML but mutations in genes other than TP53 were more frequent in t-AML than t-MDS. The molecular genetic profiling further expands our understanding in this group of clinically aggressive yet heterogeneous myeloid neoplasms.

Next generation sequencing of acute myeloid leukemia: influencing prognosis

Acute myeloid leukemia (AML) is a clonal disorder of the blood forming cells characterized by accumulation of immature blast cells in the bone marrow and peripheral blood. Being a heterogeneous disease, AML has been the subject of numerous studies that focus on unraveling the clinical, cellular and molecular variations with the aim to better understand and treat the disease. Cytogenetic-risk stratification of AML is well established and commonly used by clinicians in therapeutic management of cases with chromosomal abnormalities. Successive inclusion of novel molecular abnormalities has substantially modified the classification and understanding of AML in the past decade. With the advent of next generation sequencing (NGS) technologies the discovery of novel molecular abnormalities has accelerated. NGS has been successfully used in several studies and has provided an unprecedented overview of molecular aberrations as well as the underlying clonal evolution in AML. The extended spectrum of abnormalities discovered by NGS is currently under extensive validation for their prognostic and therapeutic values. In this review we highlight the recent advances in the understanding of AML in the NGS era.

Clonal hematopoiesis and blood-cancer risk inferred from blood DNA sequence

BACKGROUND

Cancers arise from multiple acquired mutations, which presumably occur over many years. Early stages in cancer development might be present years before cancers become clinically apparent.

METHODS

We analyzed data from whole-exome sequencing of DNA in peripheral-blood cells from 12,380 persons, unselected for cancer or hematologic phenotypes. We identified somatic mutations on the basis of unusual allelic fractions. We used data from Swedish national patient registers to follow health outcomes for 2 to 7 years after DNA sampling.

RESULTS

Clonal hematopoiesis with somatic mutations was observed in 10% of persons older than 65 years of age but in only 1% of those younger than 50 years of age. Detectable clonal expansions most frequently involved somatic mutations in three genes (DNMT3A, ASXL1, and TET2) that have previously been implicated in hematologic cancers. Clonal hematopoiesis was a strong risk factor for subsequent hematologic cancer (hazard ratio, 12.9; 95% confidence interval, 5.8 to 28.7). Approximately 42% of hematologic cancers in this cohort arose in persons who had clonality at the time of DNA sampling, more than 6 months before a first diagnosis of cancer. Analysis of bone marrow-biopsy specimens obtained from two patients at the time of diagnosis of acute myeloid leukemia revealed that their cancers arose from the earlier clones.

CONCLUSIONS

Clonal hematopoiesis with somatic mutations is readily detected by means of DNA sequencing, is increasingly common as people age, and is associated with increased risks of hematologic cancer and death. A subset of the genes that are mutated in patients with myeloid cancers is frequently mutated in apparently healthy persons; these mutations may represent characteristic early events in the development of hematologic cancers. (Funded by the National Human Genome Research Institute and others.).

Clinical massively parallel next-generation sequencing analysis of 409 cancer-related genes for mutations and copy number variations in solid tumours

Background:

In a clinical diagnostic laboratory, we evaluated the applicability of the Ion Proton sequencer for screening 409 cancer-related genes in solid tumours.

Methods:

DNA was extracted from formalin-fixed, paraffin-embedded (FFPE) tissue biopsy specimens of 55 solid tumours (20 with matched normal tissue) and four cell lines and screened for mutations in 409 genes using the Ion Proton system. The mutation profiles of these samples were known based on prior testing using the Ion Torrent Personal Genome Machine (46-gene hotspot panel), Sanger sequencing, or fluorescence in situ hybridisation (FISH). Concordance with retrospective findings and additional mutations were evaluated. Assay sensitivity and reproducibility were established. Gene copy number variations (CNVs) detected were confirmed by molecular inversion probe (MIP) array.

Results:

The average Ion Proton (409-gene panel) sequencing output per run was 8 gigabases with 128 million sequencing reads. Of the 15,992 amplicons in the 409-gene panel, 90% achieved a minimum average sequencing depth of 100X. In 59 samples, the Ion Proton detected 100 of 105 expected single-nucleotide variants (SNVs) and all expected deletions (n=8), insertions (n=5), and CNVs (n=7). Five SNVs were not detected due to failed amplification of targeted regions. In 20 tumours with paired normal tissue, Ion Proton detected 37 additional somatic mutations, several in genes of high prognostic or therapeutic significance, such as MET, ALK, TP53, APC, and PTEN. MIP array analysis confirmed all CNVs detected by Ion Proton.

Conclusions:

The Ion Proton (409-gene panel) system was found to be well suited for use in a clinical molecular diagnostic laboratory. It can simultaneously screen 409 genes for a variety of sequence variants in multiple samples using a low input of FFPE DNA with high reproducibility and sensitivity.

Role of genotype-based approach in the clinical management of adult acute myeloid leukemia with normal cytogenetics

Acute myeloid leukemia (AML) is the most common form of acute leukemia affecting adults. Although it is a complex disease driven by numerous genetic and epigenetic abnormalities, nearly 50% of patients exhibit a normal karyotype (CN-AML) with an intermediate cytogenetic risk. However, a widespread genomic analysis has recently shown the recurrence of genomic aberrations in this category (mutations of FLT3, CEBPA, NPM1, RUNX1, TET2, IDH1/2, DNMT3A, ASXL1, MLL and WT1) thus revealing its marked genomic heterogeneity. In this perspective, a global gene expression analysis of AML patients provides an independent prognostic marker to categorize each patient into clinic-pathologic subgroups based on its molecular genetic defects. Consistently such classification, taking into account the uniqueness of each AML patient, furnishes an individualized treatment approach leading a step closer to personalized medicine. Overall the genome-wide analysis of AML patients, by providing novel insights into biology of this tumor, furnishes accurate prognostic markers as well as useful tools for selecting the most appropriate treatment option. Moreover it provides novel therapeutic targets useful to enhance efficacy of the current anti-AML therapeutics. Here we describe the prognostic relevance of such new genetic data and discuss how this approach can be used to improve survival and treatment of AML patients.

CEBPA-dependent HK3 and KLF5 expression in primary AML and during AML differentiation

The basic leucine zipper transcription factor CCAAT/enhancer binding protein alpha (CEBPA) codes for a critical regulator during neutrophil differentiation. Aberrant expression or function of this protein contributes to the development of acute myeloid leukemia (AML). In this study, we identified two novel unrelated CEBPA target genes, the glycolytic enzyme hexokinase 3 (HK3) and the krüppel-like factor 5 (KLF5) transcription factor, by comparing gene profiles in two cohorts of CEBPA wild-type and mutant AML patients. In addition, we found CEBPA-dependent activation of HK3 and KLF5 transcription during all-trans retinoic acid (ATRA) mediated neutrophil differentiation of acute promyelocytic leukemia (APL) cells. Moreover, we observed direct regulation of HK3 by CEBPA, whereas our data suggest an indirect regulation of KLF5 by this transcription factor. Altogether, our data provide an explanation for low HK3 and KLF5 expression in particular AML subtype and establish these genes as novel CEBPA targets during neutrophil differentiation.

c-Met inhibition in a HOXA9/Meis1 model of CN-AML

BACKGROUND

Hematopoiesis is a paradigm for developmental processes, hierarchically organized, with stem cells at its origin. Hematopoietic stem cells (HSCs) replenish progenitor and precursor cells of multiple lineages, which normally differentiate into short-lived mature circulating cells. Hematopoiesis has provided insight into the molecular basis of tissue homeostasis and malignancy. Malignant hematopoiesis, in particular acute myeloid leukemia (AML), results from impaired development or differentiation of HSCs and progenitors. Co-overexpression of HOX and TALE genes, particularly the HOXA cluster and MEIS1, is associated with AML. Clinically relevant models of AML are required to advance drug development for an aging patient cohort.

RESULTS

Molecular analysis identified altered gene, microRNA, and protein expression in HOXA9/Meis1 leukemic bone marrow compared to normal controls. A candidate drug screen identified the c-Met inhibitor SU11274 for further analysis. Altered cell cycle status, apoptosis, differentiation, and impaired colony formation were shown for SU11274 in AML cell lines and primary leukemic bone marrow.

CONCLUSIONS

The clonal HOXA9/Meis1 AML model is amenable to drug screening analysis. The data presented indicate that human AML cells respond in a similar manner to the HOXA9/Meis1 cells, indicating pre-clinical relevance of the mouse model.

Immunotherapeutic strategies for relapse control in acute myeloid leukemia

Despite that the initial phases of chemotherapy induce disappearance of leukemic cells in many patients with acute myeloid leukemia (AML), the prevention of life-threatening relapses in the post-remission phase remains a significant clinical challenge. Allogeneic bone marrow transplantation, which is available for a minority of patients, efficiently prevents recurrences of leukemia by inducing immune-mediated elimination of leukemic cells, and over the past decades, numerous immunotherapeutic protocols have been developed aiming to mimic the graft-versus-leukemia reaction for the prevention of relapse. Here we review past and present strategies for relapse control with focus on overcoming leukemia-related immunosuppression in AML. We envisage future treatment protocols, in which systemic immune activators, such as vaccines, dendritic cell-based therapies, engineered variants of IL-2, or IL-15, are combined with agents that counter immunosuppression mediated by, e.g., the PD/PDL interaction, CTLA-4, CD200, reactive oxygen species, IDO expression, CXCR4, or the KIR/class I interaction, based on characteristics of the prevailing malignant clone. This combinatorial approach may pave the way for individualized immunotherapy in AML.

Impact of polymorphisms in drug pathway genes on disease-free survival in adults with acute myeloid leukemia

Acute myeloid leukemia (AML) is a clinically heterogeneous disease, with 5-year disease-free survival (DFS) ranging from under 10% to over 70% for distinct groups of patients. At our institution, cytarabine, etoposide and busulfan are used in first or second remission patients treated with a 2-step approach to autologous stem cell transplantation (ASCT). In this study, we tested the hypothesis that polymorphisms in the pharmacokinetic and pharmacodynamic pathway genes of these drugs are associated with DFS in AML patients. A total of 1659 variants in 42 genes were analyzed for their association with DFS using a Cox proportional hazards model. 154 genetically European patients were used for the primary analysis. An intronic SNP in ABCC3 (rs4148405) was associated with a significantly shorter DFS (HR=3.2, p=5.6 x 10(-6)) in our primary cohort. In addition a SNP in the GSTM1-GSTM5 locus, rs3754446, was significantly associated with a shorter DFS in all patients (HR=1.8, p=0.001 for 154 European ancestry; HR=1.7, p=0.028 for 125 non-European patients). Thus for the first time, genetic variants in drug pathway genes are shown to be associated with DFS in AML patients treated with chemotherapy-based autologous ASCT.