The genetic basis of myelodysplasia and its clinical relevance

Advances in Diagnosis and Risk Stratification of Acute Myeloid Leukemia and Myelodysplastic Syndromes

Advances in high-throughput DNA sequencing technology in the past decade have made a tremendous impact on basic science and clinical practice. Methods using the latest next generation sequencing technology can sequence an entire human genome within a few hours. Diagnosis and prognostication of hematologic neoplasms have moved from traditional histology and immunophenotyping to integration of cytogenetic and genomic alterations. Using illustrative cases, this chapter provides an overview of the utility of using genomic data for prognostication as well as treatment decision-making for patients with bone marrow neoplasms.

Co-occurrence of cohesin complex and Ras signaling mutations during progression from myelodysplastic syndromes to secondary acute myeloid leukemia

Myelodysplastic syndromes (MDS) are hematological disorders at high risk of progression to secondary acute myeloid leukemia (sAML). However, the mutational dynamics and clonal evolution underlying disease progression are poorly understood at present. To elucidate the mutational dynamics of pathways and genes occurring during the evolution to sAML, next generation sequencing was performed on 84 serially paired samples of MDS patients who developed sAML (discovery cohort) and 14 paired samples from MDS patients who did not progress to sAML during follow-up (control cohort). Results were validated in an independent series of 388 MDS patients (validation cohort). We used an integrative analysis to identify how mutations, alone or in combination, contribute to leukemic transformation. The study showed that MDS progression to sAML is characterized by greater genomic instability and the presence of several types of mutational dynamics, highlighting increasing (STAG2) and newly-acquired (NRAS and FLT3) mutations. Moreover, we observed cooperation between genes involved in the cohesin and Ras pathways in 15-20% of MDS patients who evolved to sAML, as well as a high proportion of newly acquired or increasing mutations in the chromatin-modifier genes in MDS patients receiving a disease-modifying therapy before their progression to sAML.

Single-cell transcriptomics dissects hematopoietic cell destruction and T-cell engagement in aplastic anemia

Aplastic anemia (AA) is a T cell-mediated autoimmune disorder of the hematopoietic system manifested by severe depletion of the hematopoietic stem and progenitor cells (HSPCs). Nonetheless, our understanding of the complex relationship between HSPCs and T cells is still obscure, mainly limited by techniques and the sparsity of HSPCs in the context of bone marrow failure. Here we performed single-cell transcriptome analysis of residual HSPCs and T cells to identify the molecular players from patients with AA. We observed that residual HSPCs in AA exhibited lineage-specific alterations in gene expression and transcriptional regulatory networks, indicating a selective disruption of distinct lineage-committed progenitor pools. In particular, HSPCs displayed frequently altered alternative splicing events and skewed patterns of polyadenylation in transcripts related to DNA damage and repair, suggesting a likely role in AA progression to myelodysplastic syndromes. We further identified cell type-specific ligand-receptor interactions as potential mediators for ongoing HSPCs destruction by T cells. By tracking patients after immunosuppressive therapy (IST), we showed that hematopoiesis remission was incomplete accompanied by IST insensitive interactions between HSPCs and T cells as well as sustained abnormal transcription state. These data collectively constitute the transcriptomic landscape of disrupted hematopoiesis in AA at single-cell resolution, providing new insights into the molecular interactions of engaged T cells with residual HSPCs and render novel therapeutic opportunities for AA.

The Genetics of Myelodysplastic Syndromes: Clinical Relevance

Myelodysplastic syndromes (MDS) are a clonal disease arising from hematopoietic stem cells, that are characterized by ineffective hematopoiesis (leading to peripheral blood cytopenia) and by an increased risk of evolution into acute myeloid leukemia. MDS are driven by a complex combination of genetic mutations that results in heterogeneous clinical phenotype and outcome. Genetic studies have enabled the identification of a set of recurrently mutated genes which are central to the pathogenesis of MDS and can be organized into a limited number of cellular pathways, including RNA splicing (SF3B1, SRSF2, ZRSR2, U2AF1 genes), DNA methylation (TET2, DNMT3A, IDH1/2), transcription regulation (RUNX1), signal transduction (CBL, RAS), DNA repair (TP53), chromatin modification (ASXL1, EZH2), and cohesin complex (STAG2). Few genes are consistently mutated in >10% of patients, whereas a long tail of 40-50 genes are mutated in <5% of cases. At diagnosis, the majority of MDS patients have 2-4 driver mutations and hundreds of background mutations. Reliable genotype/phenotype relationships were described in MDS: SF3B1 mutations are associated with the presence of ring sideroblasts and more recent studies indicate that other splicing mutations (SRSF2, U2AF1) may identify distinct disease categories with specific hematological features. Moreover, gene mutations have been shown to influence the probability of survival and risk of disease progression and mutational status may add significant information to currently available prognostic tools. For instance, SF3B1 mutations are predictors of favourable prognosis, while driver mutations of other genes (such as ASXL1, SRSF2, RUNX1, TP53) are associated with a reduced probability of survival and increased risk of disease progression. In this article, we review the most recent advances in our understanding of the genetic basis of myelodysplastic syndromes and discuss its clinical relevance.

Mechanistic Insights of Aberrant Splicing with Splicing Factor Mutations Found in Myelodysplastic Syndromes

Pre-mRNA splicing is an essential process for gene expression in higher eukaryotes, which requires a high order of accuracy. Mutations in splicing factors or regulatory elements in pre-mRNAs often result in many human diseases. Myelodysplastic syndrome (MDS) is a heterogeneous group of chronic myeloid neoplasms characterized by many symptoms and a high risk of progression to acute myeloid leukemia. Recent findings indicate that mutations in splicing factors represent a novel class of driver mutations in human cancers and affect about 50% of Myelodysplastic syndrome (MDS) patients. Somatic mutations in MDS patients are frequently found in genes SF3B1, SRSF2, U2AF1, and ZRSR2. Interestingly, they are involved in the recognition of 3' splice sites and exons. It has been reported that mutations in these splicing regulators result in aberrant splicing of many genes. In this review article, we first describe molecular mechanism of pre-mRNA splicing as an introduction and mainly focus on those four splicing factors to describe their mutations and their associated aberrant splicing patterns.

Diagnostic Challenge and Clinical Dilemma: The Long Reach of Clonal Hematopoiesis

BACKGROUND

Widespread application of massively parallel sequencing has resulted in recognition of clonal hematopoiesis in various clinical settings and on a relatively frequent basis. Somatic mutations occur in individuals with normal blood counts, and increase in frequency with age. The genes affected are the same genes that are commonly mutated in overt myeloid malignancies such as acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). This phenomenon is referred to as clonal hematopoiesis of indeterminate potential (CHIP).

CONTENT

In this review, we explore the diagnostic and clinical implications of clonal hematopoiesis. In addition to CHIP, clonal hematopoiesis may be seen in patients with cytopenia who do not otherwise meet criteria for hematologic malignancy, a condition referred to as clonal cytopenia of undetermined significance (CCUS). Distinguishing CHIP and CCUS from overt myeloid neoplasm is a challenge to diagnosticians due to the overlapping mutational landscape observed in these conditions. We describe helpful laboratory and clinical features in making this distinction. CHIP confers a risk of progression to overt hematologic malignancy similar to other premalignant states. CHIP is also associated with a proinflammatory state with multisystem implications and increased mortality risk due to cardiovascular events. The current approach to follow up and management of patients with clonal hematopoiesis is described.

SUMMARY

Nuanced understanding of clonal hematopoiesis is essential for diagnosis and clinical management of patients with hematologic conditions. Further data are needed to more accurately predict the natural history and guide management of these patients with respect to both malignant progression as well as nonhematologic sequelae.

Clinical relevance of clonal hematopoiesis in the oldest-old population

Clonal hematopoiesis of indeterminate potential (CHIP) is associated with increased risk of cancers and inflammation-related diseases. This phenomenon becomes very common in oldest-old individuals, in whom the implications of CHIP are not well defined. We performed a mutational screening in 1794 oldest-old individuals enrolled in two population-based studies and investigate the relationships between CHIP and associated pathologies. Clonal mutations were observed in one third of oldest-old individuals and were associated with reduced survival. Mutations in JAK2 and splicing genes, multiple mutations (DNMT3A, TET2, ASXL1 with additional genetic lesions) and variant allele frequency ≥0.096 had positive predictive value for myeloid neoplasms. Combining mutation profiles with abnormalities in red blood cell indices improved the ability of myeloid neoplasm prediction. On this basis, we defined a predictive model that identifies 3 risk groups with different probabilities of developing myeloid neoplasms. Mutations in DNMT3A, TET2, ASXL1 or JAK2 (most occurring as single lesion) were associated with coronary heart disease and rheumatoid arthritis. Cytopenia was a common finding in oldest-old population, the underlying cause remaining unexplained in 30% of cases. Among individuals with unexplained cytopenia, the presence of highly-specific mutation patterns was associated with myelodysplastic-like phenotype and a probability of survival comparable to that of myeloid neoplasms. Accordingly, 7.5% of oldest-old subjects with cytopenia had presumptive evidence of myeloid neoplasm. In conclusion, specific mutational patterns define different risk of developing myeloid neoplasms vs. inflammatory-associated diseases in oldest-old population. In individuals with unexplained cytopenia, mutational status may identify those subjects with presumptive evidence of myeloid neoplasms.

Oligomonocytic and overt chronic myelomonocytic leukemia show similar clinical, genomic, and immunophenotypic features

Oligomonocytic chronic myelomonocytic leukemia (OM-CMML) is defined as those myelodysplastic syndromes (MDSs) or myelodysplastic/myeloproliferative neoplasms, unclassifiable with relative monocytosis (≥10% monocytes) and a monocyte count of 0.5 to <1 × 109/L. These patients show clinical and genomic features similar to those of overt chronic myelomonocytic leukemia (CMML), although most of them are currently categorized as MDS, according to the World Health Organization 2017 classification. We analyzed the clinicopathologic features of 40 patients with OM-CMML with well-annotated immunophenotypic and molecular data and compared them to those of 56 patients with overt CMML. We found similar clinical, morphological, and cytogenetic features. In addition, OM-CMML mirrored the well-known complex molecular profile of CMML, except for the presence of a lower percentage of RAS pathway mutations. In this regard, of the different genes assessed, only CBL was found to be mutated at a significantly lower frequency. Likewise, the OM-CMML immunophenotypic profile, assessed by the presence of >94% classical monocytes (MO1s) and CD56 and/or CD2 positivity in peripheral blood monocytes, was similar to overt CMML. The MO1 percentage >94% method showed high accuracy for predicting CMML diagnosis (sensitivity, 90.7%; specificity, 92.2%), even when considering OM-CMML as a subtype of CMML (sensitivity, 84.9%; specificity, 92.1%) in our series of 233 patients (39 OM-CMML, 54 CMML, 23 MDS, and 15 myeloproliferative neoplasms with monocytosis and 102 reactive monocytosis). These results support the consideration of OM-CMML as a distinctive subtype of CMML.

Genetic Aspects of Myelodysplastic/Myeloproliferative Neoplasms

Simple Summary

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are clonal myeloid neoplasms characterized, at the time of their presentation, by the simultaneous presence of both myelodysplastic and myeloproliferative features. In MDS/MPN, the karyotype is often normal but mutations in genes that are common across myeloid neoplasms can be detected in a high proportion of cases by targeted sequencing. In this review, we intend to summarize the main genetic findings across all MDS/MPN overlap syndromes and discuss their relevance in the management of patients.

Abstract

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are myeloid neoplasms characterized by the presentation of overlapping features from both myelodysplastic syndromes and myeloproliferative neoplasms. Although the classification of MDS/MPN relies largely on clinical features and peripheral blood and bone marrow morphology, studies have demonstrated that a large proportion of patients (~90%) with this disease harbor somatic mutations in a group of genes that are common across myeloid neoplasms. These mutations play a role in the clinical heterogeneity of these diseases and their clinical evolution. Nevertheless, none of them is specific to MDS/MPN and current diagnostic criteria do not include molecular data. Even when such alterations can be helpful for differential diagnosis, they should not be used alone as proof of neoplasia because some of these mutations may also occur in healthy older people. Here, we intend to review the main genetic findings across all MDS/MPN overlap syndromes and discuss their relevance in the management of the patients.

Myelodysplasia Syndrome, Clonal Hematopoiesis and Cardiovascular Disease

Simple Summary

The development of blood cancers is a complex process that involves the acquisition of specific blood disorders that precede cancer. These blood disorders are often driven by the accumulation of genetic abnormalities, which are discussed in this review. Likewise, predicting the rate of progression of these diseases is difficult, but it appears to be linked to which specific gene mutations are present in blood cells. In this review, we discuss a variety of genetic abnormalities that drive blood cancer, conditions that precede clinical symptoms of blood cancer, and how alterations in these genes change blood cell function. Additionally, we discuss the novel links between blood cancer development and heart disease.

Abstract

The development of myelodysplasia syndromes (MDS) is multiphasic and can be driven by a plethora of genetic mutations and/or abnormalities. MDS is characterized by a hematopoietic differentiation block, evidenced by increased immature hematopoietic cells, termed blast cells and decreased mature circulating leukocytes in at least one lineage (i.e., cytopenia). Clonal hematopoiesis of indeterminate potential (CHIP) is a recently described phenomenon preceding MDS development that is driven by somatic mutations in hemopoietic stem cells (HSCs). These mutant HSCs have a competitive advantage over healthy cells, resulting in an expansion of these clonal mutated leukocytes. In this review, we discuss the multiphasic development of MDS, the common mutations found in both MDS and CHIP, how a loss-of-function in these CHIP-related genes can alter HSC function and leukocyte development and the potential disease outcomes that can occur with dysfunctional HSCs. In particular, we discuss the novel connections between MDS development and cardiovascular disease.

Point Mutation Specific Antibodies in B-Cell and T-Cell Lymphomas and Leukemias: Targeting IDH2, KRAS, BRAF and Other Biomarkers RHOA, IRF8, MYD88, ID3, NRAS, SF3B1 and EZH2

B-cell and T-cell lymphomas and leukemias often have distinct genetic mutations that are diagnostically defining or prognostically significant. A subset of these mutations consists of specific point mutations, which can be evaluated using genetic sequencing approaches or point mutation specific antibodies. Here, we describe genes harboring point mutations relevant to B-cell and T-cell malignancies and discuss the current availability of these targeted point mutation specific antibodies. We also evaluate the possibility of generating novel antibodies against known point mutations by computationally assessing for chemical and structural features as well as epitope antigenicity of these targets. Our results not only summarize several genetic mutations and identify existing point mutation specific antibodies relevant to hematologic malignancies, but also reveal potential underdeveloped targets which merit further study.

Prognostic mutation constellations in acute myeloid leukaemia and myelodysplastic syndrome

PURPOSE OF REVIEW

In the past decade, numerous studies analysing the genome and transcriptome of large cohorts of acute myeloid leukaemia (AML) and myelodysplastic syndrome (MDS) patients have substantially improved our knowledge of the genetic landscape of these diseases with the identification of heterogeneous constellations of germline and somatic mutations with prognostic and therapeutic relevance. However, inclusion of integrated genetic data into classification schema is still far from a reality. The purpose of this review is to summarize recent insights into the prevalence, pathogenic role, clonal architecture, prognostic impact and therapeutic management of genetic alterations across the spectrum of myeloid malignancies.

RECENT FINDINGS

Recent multiomic-studies, including analysis of genetic alterations at the single-cell resolution, have revealed a high heterogeneity of lesions in over 200 recurrently mutated genes affecting disease initiation, clonal evolution and clinical outcome. Artificial intelligence and specifically machine learning approaches have been applied to large cohorts of AML and MDS patients to define in an unbiased manner clinically meaningful disease patterns including, disease classification, prognostication and therapeutic vulnerability, paving the way for future use in clinical practice.

SUMMARY

Integration of genomic, transcriptomic, epigenomic and clinical data coupled to conventional and machine learning approaches will allow refined leukaemia classification and risk prognostication and will identify novel therapeutic targets for these still high-risk leukaemia subtypes.

Mutations in genes affecting DNA methylation enhances responses to decitabine in patients with myelodysplastic syndrome

BACKGROUND/AIMS

In this study, we tested whether mutations in the methylation pathway genes ten-eleven-translocation 2 (TET2) and DNA methyltransferase gene 3A (DNMT3A) improve the responses of patients with myelodysplastic syndrome (MDS) to decitabine.

METHODS

We retrospectively sequenced the TET2 and DNMT3A genes from 70 patients diagnosed with de novo MDS between June 2008 and December 2011 and treated with a 5-day regimen of decitabine (290 cycles). We then analyzed treatment outcomes.

RESULTS

Patients with hematological improvement survived longer than those without hematological improvement (22.9 months vs. 10.9 months, p = 0.006). Among the 70 patients, 12 (17.1%) carried TET2 or DNMT3A mutations. The baseline characteristics of patients with wild type or mutated genes were similar. Patients with mutations in TET2 or DNMT3A had a higher overall response rate than those with the wild type genes (82.3% vs. 46.6%, p = 0.023). Multivariate analysis demonstrated that the TET2 or DMNT3A mutation status was associated with improved treatment responses and better overall survival among patients receiving decitabine.

CONCLUSION

These results demonstrate that TET2 mutations enhance the treatment response of MDS patients to hypomethylating agents like decitabine.

Myelodysplastic syndromes with ring sideroblasts (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T) - "2021 update on diagnosis, risk-stratification, and management"

DISEASE OVERVIEW

Ring sideroblasts (RS) are erythroid precursors with abnormal perinuclear mitochondrial iron accumulation. Two myeloid neoplasms defined by the presence of RS, include myelodysplastic syndromes with RS (MDS-RS) and MDS/myeloproliferative neoplasm with RS and thrombocytosis (MDS/MPN-RS-T).

DIAGNOSIS

MDS-RS is a lower risk MDS, with single or multilineage dysplasia (MDS-RS-SLD/MLD), <5% bone marrow (BM) blasts, <1% peripheral blood blasts and ≥15% BM RS (≥5% in the presence of SF3B1 mutations). MDS/MPN-RS-T, now a formal entity in the MDS/MPN overlap syndromes, has diagnostic features of MDS-RS-SLD, along with a platelet count ≥450 × 10⁹ /L and large atypical megakaryocytes.

MUTATIONS AND KARYOTYPE

Mutations in SF3B1 are seen in ≥80% of patients with MDS-RS-SLD and MDS/MPN-RS-T, and strongly correlate with the presence of BM RS; MDS/MPN-RS-T patients also demonstrate JAK2V617F (50%), DNMT3A, TET2 and ASXL1 mutations. Cytogenetic abnormalities are uncommon in both.

RISK STRATIFICATION

Most patients with MDS-RS-SLD are stratified into lower risk groups by the revised-IPSS. Disease outcome in MDS/MPN-RS-T is better than that of MDS-RS-SLD, but worse than that of essential thrombocythemia (MPN). Both diseases are associated with a low risk of leukemic transformation.

TREATMENT

Anemia and iron overload are complications seen in both and are managed similar to lower risk MDS and MPN. Luspatercept, a first-in-class erythroid maturation agent is now approved for the management of anemia in patients with MDS-RS and MDS/MPN-RS-T. Aspirin therapy is reasonable in MDS/MPN-RS-T, especially in the presence of JAK2V617F, but the value of platelet-lowering drugs remains to be defined.

Molecular Targeted Therapy in Myelodysplastic Syndromes: New Options for Tailored Treatments

Simple Summary

Myelodysplastic syndromes (MDS) are a group of diseases in which bone marrow stem cells acquire genetic alterations and can initiate leukemia, blocking the production of mature blood cells. It is of crucial importance to identify those genetic abnormalities because some of them can be the targeted. To date only very few drugs are approved for patients manifesting this group of disorders and there is an urgent need to develop new effective therapies. This review gives an overview of the genetic of MDS and the therapeutic options available and in clinical experimentation.

Abstract

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic disorders characterized by ineffective hematopoiesis, progressive cytopenias and increased risk of transformation to acute myeloid leukemia. The improved understanding of the underlying biology and genetics of MDS has led to better disease and risk classification, paving the way for novel therapeutic opportunities. Indeed, we now have a vast pipeline of targeted agents under pre-clinical and clinical development, potentially able to modify the natural history of the diverse disease spectrum of MDS. Here, we review the latest therapeutic approaches (investigational and approved agents) for MDS treatment. A deep insight will be given to molecularly targeted therapies by reviewing new agents for individualized precision medicine.

Classification and Personalized Prognostic Assessment on the Basis of Clinical and Genomic Features in Myelodysplastic Syndromes

Recurrently mutated genes and chromosomal abnormalities have been identified in myelodysplastic syndromes (MDS). We aim to integrate these genomic features into disease classification and prognostication.

Exosomes and Extracellular Vesicles in Myeloid Neoplasia: The Multiple and Complex Roles Played by These "Magic Bullets"

Simple Summary

Extracellular vesicles (EVs) are released by the majority of cell types and can be isolated from both cell cultures and body fluids. They are involved in cell-to-cell communication and may shuttle different messages (RNA, DNA, and proteins). These messages are known to influence the microenvironment of cells and their behavior. In recent years, some evidence about the involvement of EVs and exosomes, an EV subgroup, in immunomodulation, the transfer of disease markers, and the treatment of myeloid malignancies have been reported. Little is known about these vesicles in this particular setting of hematologic neoplasia; here, we summarize and critically review the available results, aiming to encourage further investigations.

Abstract

Extracellular vesicles (exosomes, in particular) are essential in multicellular organisms because they mediate cell-to-cell communication via the transfer of secreted molecules. They are able to shuttle different cargo, from nucleic acids to proteins. The role of exosomes has been widely investigated in solid tumors, which gave us surprising results about their potential involvement in pathogenesis and created an opening for liquid biopsies. Less is known about exosomes in oncohematology, particularly concerning the malignancies deriving from myeloid lineage. In this review, we aim to present an overview of immunomodulation and the microenvironment alteration mediated by exosomes released by malicious myeloid cells. Afterwards, we review the studies reporting the use of exosomes as disease biomarkers and their influence in response to treatment, together with the recent experiences that have focused on the use of exosomes as therapeutic tools. The further development of new technologies and the increased knowledge of biological (exosomes) and clinical (myeloid neoplasia) aspects are expected to change the future approaches to these malignancies.

Clonal hematopoiesis in adult pure red cell aplasia

Idiopathic pure red cell aplasia (PRCA) and secondary PRCA associated with thymoma and large granular lymphocyte leukemia are generally considered to be immune-mediated. The PRCA2004/2006 study showed that poor responses to immunosuppression and anemia relapse were associated with death. PRCA may represent the prodrome to MDS. Thus, clonal hematopoiesis may be responsible for treatment failure. We investigated gene mutations in myeloid neoplasm-associated genes in acquired PRCA. We identified 21 mutations affecting amino acid sequences in 11 of the 38 adult PRCA patients (28.9%) using stringent filtering of the error-prone sequences and SNPs. Four PRCA patients showed 7 driver mutations in TET2, DNMT3A and KDM6A, and 2 PRCA patients carried multiple mutations in TET2. Five PRCA patients had mutations with high VAFs exceeding 0.3. These results suggest that clonal hematopoiesis by stem/progenitor cells might be related to the pathophysiology of chronic PRCA in certain adult patients.

The Importance of Targeted Next-Generation Sequencing Usage in Cytogenetically Normal Myeloid Malignancies

Advanced diagnostic methods give an advantage for the identification of abnormalities in myeloid malignancies. Various researchers have shown the potential importance of genetic tests before the disease's onset and in remission. Large testing panels prevent false-negative results in myeloid malignancies. However, the critical question is how the results of conventional cytogenetic and molecular cytogenetic techniques can be merged with NGS technologies. In this paper, we drew an algorithm for the evaluation of myeloid malignancies. To evaluate genetic abnormalities, we performed cytogenetics, molecular cytogenetics, and NGS testing in myeloid malignancies. In this study, we analyzed 100 patients admitted to the Medical Genetics Laboratory with different myeloid malignancies. We highlighted the possible diagnostic algorithm for cytogenetically normal cases. We applied NGS 141 gene panel for cytogenetically normal patients, and we detected two or more pathogenic variations in 61 out of 100 patients (61%). NGS's pathogenic variation detection rate varies in disease groups: they were present in 85% of A.M.L. and 23% of M.D.S. Here, we identified 24 novel variations out of total pathogenic variations in myeloid malignancies. A total of 18 novel variations were identified in A.M.L., and 6 novel variations were identified in M.D.S. Despite long turnaround times, conventional techniques are still a golden standard for myeloid malignancies but sometimes cryptic gene fusions or complex abnormalities cannot be easily identified by conventional techniques. In these conditions, advanced technologies like NGS are highly recommended.

Identification of Novel Insertions and Deletions in Haematopoietic Stem/Progenitor Cells in de novo Myelodysplastic Syndromes

Myelodysplastic Syndromes (MDS) are clonal haematological stem cell disorders. The molecular basis of MDS is heterogeneous and the molecular mechanisms underlying biology of this complex disorder are not fully understood. Genetic variations (GVs) occur in about 90% of patients with MDS. It has been shown that in addition to the single nucleotide variations, insertions and deletions (indels) in the key genes that are known to drive MDS, could also play a role in pathogenesis of MDS. However, only a few genetic studies have analyzed indels in MDS. The present study reports indels of bone marrow (BM) derived CD34⁺ haematopoietic stem/progenitor cells of 20 newly diagnosed de novo MDS patients using next generation sequencing.A total of 88 indels (9 insertions and 79 deletions) across 28 genes were observed. The genes that showed more than five indels are BCOR (N=6), RAD21 (N=6), TP53 (N=8), ASXL1 (N=9), TET2 (N=9) and BCORL1 (N=10). Deletion in the BCORL1 gene (c.3957_3959delGGA, TGAG>TGAG/T) was the most recurrent deletion and was observed in 4/20 patients. The other recurrent deletions reported were EZH2 (W15X, N=2) and RAD21 (G274X, N=3). The recurrent insertions were detected in the FLT3 (E598DYVDFREYE, N=3) and in the NPM1 (L287LCX, N=3) genes. The findings of this study may have a diagnostic, prognostic and a therapeutic value for MDS after validation using a larger cohort.

Epigenetic modifiers in normal and aberrent erythropoeisis

Erythroid differentiation program is comprised of lineage commitment, erythroid progenitor proliferation, and termination differentiation. Each stage of the differentiation program is heavily influenced by epigenetic modifiers that alter the epigenome in a dynamic fashion influenced by cytokines/humeral factors and are amicable to target by drugs. The epigenetic modifiers can be classified as DNA modifiers (DNMT, TET), mRNA modifiers (RNA methylases and demethylases) and histone protein modifiers (methyltransferases, acetyltransferases, demethylases, and deacetylases). Here we describe mechanisms by which these epigenetic modifiers influence and guide erythroid-lineage differentiation during normal and malignant erythropoiesis and also benign diseases that arise from their altered structure or function.

The altered transcriptome of pediatric myelodysplastic syndrome revealed by RNA sequencing

Pediatric myelodysplastic syndrome (PMDS) is a very rare and still poorly characterized disorder. In this work, we identified novel potential targets of PMDS by determining genes with aberrant expression, which can be correlated with PMDS pathogenesis. We identified 291 differentially expressed genes (DEGs) in PMDS patients, comprising genes involved in the regulation of apoptosis and the cell cycle, ribosome biogenesis, inflammation and adaptive immunity. Ten selected DEGs were then validated, confirming the sequencing data. These DEGs will potentially represent new molecular biomarkers and therapeutic targets for PMDS.

DNA methylation identifies genetically and prognostically distinct subtypes of myelodysplastic syndromes

Recurrent mutations implicate several epigenetic regulators in the early molecular pathobiology of myelodysplastic syndromes (MDS). We hypothesized that MDS subtypes defined by DNA methylation (DNAm) patterns could enhance our understanding of MDS disease biology and identify patients with convergent epigenetic profiles. Bisulfite padlock probe sequencing was used to measure DNAm of ∼500 000 unique cytosine guanine dinucleotides covering 140 749 nonoverlapping regulatory regions across the genome in bone marrow DNA samples from 141 patients with MDS. Application of a nonnegative matrix factorization (NMF)-based decomposition of DNAm profiles identified 5 consensus clusters described by 5 NMF components as the most stable grouping solution. Each of the 5 NMF components identified by this approach correlated with specific genetic abnormalities and categorized patients into 5 distinct methylation clusters, each largely defined by a single NMF component. Methylation clusters displayed unique differentially methylated regulatory loci enriched for active and bivalent promoters and enhancers. Two clusters were enriched for samples with complex karyotypes, although only one had an increased number of TP53 mutations. Each of the 3 most frequently mutated splicing factors, SF3B1, U2AF1, and SRSF2, was enriched in different clusters. Mutations of ASXL1, EZH2, and RUNX1 were coenriched in the SRSF2-containing cluster. In multivariate analysis, methylation cluster membership remained independently associated with overall survival. Targeted DNAm profiles identify clinically relevant subtypes of MDS not otherwise distinguished by mutations or clinical features. Patients with diverse genetic lesions can converge on common DNAm states with shared pathogenic mechanisms and clinical outcomes.

Prognostic Markers of Myelodysplastic Syndromes

Myelodysplastic syndrome (MDS) is a clonal disease characterized by multilineage dysplasia, peripheral blood cytopenias, and a high risk of transformation to acute myeloid leukemia. In theory, from clonal hematopoiesis of indeterminate potential to hematologic malignancies, there is a complex interplay between genetic and epigenetic factors, including miRNA. In practice, karyotype analysis assigns patients to different prognostic groups, and mutations are often associated with a particular disease phenotype. Among myeloproliferative disorders, secondary MDS is a group of special entities with a typical spectrum of genetic mutations and cytogenetic rearrangements resembling those in de novo MDS. This overview analyzes the present prognostic systems of MDS and the most recent efforts in the search for genetic and epigenetic markers for the diagnosis and prognosis of MDS.

SF3B1-mutant MDS as a distinct disease subtype: a proposal from the International Working Group for the Prognosis of MDS

The 2016 revision of the World Health Organization classification of tumors of hematopoietic and lymphoid tissues is characterized by a closer integration of morphology and molecular genetics. Notwithstanding, the myelodysplastic syndrome (MDS) with isolated del(5q) remains so far the only MDS subtype defined by a genetic abnormality. Approximately half of MDS patients carry somatic mutations in spliceosome genes, with SF3B1 being the most commonly mutated one. SF3B1 mutation identifies a condition characterized by ring sideroblasts (RS), ineffective erythropoiesis, and indolent clinical course. A large body of evidence supports recognition of SF3B1-mutant MDS as a distinct nosologic entity. To further validate this notion, we interrogated the data set of the International Working Group for the Prognosis of MDS (IWG-PM). Based on the findings of our analyses, we propose the following diagnostic criteria for SF3B1-mutant MDS: (1) cytopenia as defined by standard hematologic values, (2) somatic SF3B1 mutation, (3) morphologic dysplasia (with or without RS), and (4) bone marrow blasts <5% and peripheral blood blasts <1%. Selected concomitant genetic lesions represent exclusion criteria for the proposed entity. In patients with clonal cytopenia of undetermined significance, SF3B1 mutation is almost invariably associated with subsequent development of overt MDS with RS, suggesting that this genetic lesion might provide presumptive evidence of MDS in the setting of persistent unexplained cytopenia. Diagnosis of SF3B1-mutant MDS has considerable clinical implications in terms of risk stratification and therapeutic decision making. In fact, this condition has a relatively good prognosis and may respond to luspatercept with abolishment of the transfusion requirement.

Combined loss of function of two different loci of miR-15/16 drives the pathogenesis of acute myeloid leukemia

Double knockout of the two miR-15/16 loci in mouse resulted in the development of acute myeloid leukemia (AML). This result suggested that, at least, a fraction of human AMLs could be due to a similar mechanism. We analyzed the role of the two miR-15/16 clusters in 93 myelodysplastic syndrome (MDS) patients divided in three subgroups: patients with MDS, patients with MDS before transforming into AML (MDS-T), and patients with AML evolving from MDS (MDS-AML). Then, we tested 139 AML cases and 14 different AML cell lines by assessing microRNA (miRNA) expression, target protein expression, genetic loss, and silencing. MDS-T and MDS-AML patients show a reduction of the expression of miR-15a/-15b/-16 compared to MDS patients. Each miRNA can significantly predict MDS and MDS-T groups. Then, 79% of primary AMLs show a reduced expression of miR-15a and/or miR-15b. The expression of miR-15a/-15b/-16 significantly stratified AML patients in two prognostic classes. Furthermore, 40% of AML cell lines showed a combined loss of the expression of miR-15a/-15b and overexpression of their direct/indirect targets. As potential mechanisms involved in the silencing of the two miR-15/16 loci, we identified a genetic loss of miR-15a and miR-15b and silencing of these two loci by methylation. We identified a potential driver oncogenic role in the loss of expression of both miR-15/16 clusters in the progression of MDS into AML and in AML pathogenesis. The stratification of AML patients, based on miR-15/16 expression, can lead to targeted and combination therapies for the treatment of this incurable disease.

Combined Cohesin-RUNX1 Deficiency Synergistically Perturbs Chromatin Looping and Causes Myelodysplastic Syndromes

STAG2 encodes a cohesin component and is frequently mutated in myeloid neoplasms, showing highly significant comutation patterns with other drivers, including RUNX1. However, the molecular basis of cohesin-mutated leukemogenesis remains poorly understood. Here we show a critical role of an interplay between STAG2 and RUNX1 in the regulation of enhancer-promoter looping and transcription in hematopoiesis. Combined loss of STAG2 and RUNX1, which colocalize at enhancer-rich, CTCF-deficient sites, synergistically attenuates enhancer-promoter loops, particularly at sites enriched for RNA polymerase II and Mediator, and deregulates gene expression, leading to myeloid-skewed expansion of hematopoietic stem/progenitor cells (HSPC) and myelodysplastic syndromes (MDS) in mice. Attenuated enhancer-promoter loops in STAG2/RUNX1-deficient cells are associated with downregulation of genes with high basal transcriptional pausing, which are important for regulation of HSPCs. Downregulation of high-pausing genes is also confirmed in STAG2-cohesin-mutated primary leukemia samples. Our results highlight a unique STAG2-RUNX1 interplay in gene regulation and provide insights into cohesin-mutated leukemogenesis. SIGNIFICANCE: We demonstrate a critical role of an interplay between STAG2 and a master transcription factor of hematopoiesis, RUNX1, in MDS development, and further reveal their contribution to regulation of high-order chromatin structures, particularly enhancer-promoter looping, and the link between transcriptional pausing and selective gene dysregulation caused by cohesin deficiency.This article is highlighted in the In This Issue feature, p. 747.

Molecular Landscape of Acute Myeloid Leukemia: Prognostic and Therapeutic Implications

PURPOSE OF REVIEW

The field of acute myeloid leukemia (AML) has been revolutionized in recent years by the advent of high-throughput techniques, such as next-generation sequencing. In this review, we will discuss some of the recently identified mutations that have defined a new molecular landscape in this disease, as well as their prognostic, predictive, and therapeutic implications.

RECENT FINDINGS

Recent studies have shown how many cases of AML evolve from a premalignant period of latency characterized by the accumulation of several mutations and the emergence of one or multiple dominant clones. The pattern of co-occurring mutations and cytogenetic abnormalities at diagnosis defines risk and can determine therapeutic approaches to induce remission. Besides the genetic landscape at diagnosis, the continued presence of particular gene mutations during or after treatment carries prognostic information that should further influence strategies to maintain remission in the long term. The recent progress made in AML research is a seminal example of how basic science can translate into improving clinical practice. Our ability to characterize the genomic landscape of individual patients has not only improved our ability to diagnose and prognosticate but is also bringing the promise of precision medicine to fruition in the field.

Do next-generation sequencing results drive diagnostic and therapeutic decisions in MDS?

This article has a companion Point by Thol and Platzbecker.

Invariant phenotype and molecular association of biallelic TET2 mutant myeloid neoplasia

Somatic TET2 mutations (TET2 ^MT) are frequent in myeloid neoplasia (MN), particularly chronic myelomonocytic leukemia (CMML). TET2 ^MT includes mostly loss-of-function/hypomorphic hits. Impaired TET2 activity skews differentiation of hematopoietic stem cells toward proliferating myeloid precursors. This study was prompted by the observation of frequent biallelic TET2 gene inactivations (biTET2 ⁱ ) in CMML. We speculated that biTET2 ⁱ might be associated with distinct clinicohematological features. We analyzed TET2 ^MT in 1045 patients with MN. Of 82 biTET2 ⁱ cases, 66 were biTET2 ^MT, 13 were hemizygous TET2 ^MT, and 3 were homozygous TET2 ^MT (uniparental disomy); the remaining patients (denoted biTET2 ^- hereafter) were either monoallelic TET2 ^MT (n = 96) or wild-type TET2 (n = 823). Truncation mutations were found in 83% of biTET2 ⁱ vs 65% of biTET2 ^- cases (P = .02). TET2 hits were founder lesions in 72% of biTET2 ⁱ vs 38% of biTET2 ^- cases (P < .0001). In biTET2 ⁱ , significantly concurrent hits included SRSF2 ^MT (33%; P < .0001) and KRAS/NRAS ^MT (16%; P = .03) as compared with biTET2 ^- When the first TET2 hit was ancestral in biTET2 ⁱ , the most common subsequent hits affected a second TET2 ^MT, followed by SRSF2 ^MT, ASXL1 ^MT, RAS ^MT, and DNMT3A ^MT BiTET2 ⁱ patients without any monocytosis showed an absence of SRSF2 ^MT BiTET2 ⁱ patients were older and had monocytosis, CMML, normal karyotypes, and lower-risk disease compared with biTET2 ^- patients. Hence, while a second TET2 hit occurred frequently, biTET2 ⁱ did not portend faster progression but rather determined monocytic differentiation, consistent with its prevalence in CMML. Additionally, biTET2 ⁱ showed lower odds of cytopenias and marrow blasts (≥5%) and higher odds of myeloid dysplasia and marrow hypercellularity. Thus, biTET2 ⁱ might represent an auxiliary assessment tool in MN.

The Clinical, Molecular, and Mechanistic Basis of RUNX1 Mutations Identified in Hematological Malignancies

RUNX1 plays an important role in the regulation of normal hematopoiesis. RUNX1 mutations are frequently found and have been intensively studied in hematological malignancies. Germline mutations in RUNX1 cause familial platelet disorder with predisposition to acute myeloid leukemia (FPD/AML). Somatic mutations of RUNX1 are observed in various types of hematological malignancies, such as AML, acute lymphoblastic leukemia (ALL), myelodysplastic syndromes (MDS), myeloproliferative neoplasm (MPN), chronic myelomonocytic leukemia (CMML), and congenital bone marrow failure (CBMF). Here, we systematically review the clinical and molecular characteristics of RUNX1 mutations, the mechanisms of pathogenesis caused by RUNX1 mutations, and potential therapeutic strategies to target RUNX1-mutated cases of hematological malignancies.

Impact of somatic mutations in myelodysplastic patients with isolated partial or total loss of chromosome 7

Monosomy 7 [-7] and/or partial loss of chromosome 7 [del(7q)] are associated with poor and intermediate prognosis, respectively, in myelodysplastic syndromes (MDS), but somatic mutations may also play a key complementary role. We analyzed the impact on the outcomes of deep targeted mutational screening in 280 MDS patients with -7/del(7q) as isolated cytogenetic abnormality (86 with del(7q) and 194 with -7). Patients with del(7q) or -7 had similar demographic and disease-related characteristics. Somatic mutations were detected in 79% (93/117) of patients (82% in -7 and 73% in del(7q) group). Median number of mutations per patient was 2 (range 0-8). There was no difference in mutation frequency between the two groups. Patients harbouring ≥2 mutations had a worse outcome than patients with <2 or no mutations (leukaemic transformation at 24 months, 38% and 20%, respectively, p = 0.044). Untreated patients with del(7q) had better overall survival (OS) compared with -7 (median OS, 34 vs 17 months, p = 0.034). In multivariable analysis, blast count, TP53 mutations and number of mutations were independent predictors of OS, whereas the cytogenetic subgroups did not retain prognostic relevance. This study highlights the importance of mutational analysis in terms of prognosis in MDS patients with isolated -7 or del(7q).

Humanized mice as preclinical models for myeloid malignancies

Humanized mice have proven to be invaluable for human hematological translational research since they offer essential tools to dissect disease biology and to bridge the gap between pre-clinical testing of novel therapeutics and their clinical applications. Many efforts have been placed to advance and optimize humanized mice to support the engraftment, differentiation, and maintenance of hematopoietic stem cells (HSCs) and the human hematological system in order to broaden the scope of applications of such models. This review covers the background of humanized mice, how they are used as platforms to model myeloid malignancies, and the various current and potential approaches to further enhance their utilization in biomedical research.

Acute Myeloid Leukemia: Aging and Epigenetics

Acute myeloid leukemia (AML) is an aggressive hematological disorder mainly affecting people of older age. AML initiation is primarily attributed to mutations in crucial cellular regulators such as epigenetic factors, transcription factors, and signaling genes. AML’s aggressiveness and responsiveness to treatment depends on the specific cell type where leukemia first arose. Aged hematopoietic cells are often genetically and/or epigenetically altered and, therefore, present with a completely different cellular context for AML development compared to young cells. In this review, we summarize key aspects of AML development, and we focus, in particular, on the contribution of cellular aging to leukemogenesis and on current treatment options for elderly AML patients. Hematological disorders and leukemia grow exponentially with age. So far, with conventional induction therapy, many elderly patients experience a very poor overall survival rate requiring substantial social and medical costs during the relatively few remaining months of life. The global population’s age is increasing rapidly without an acceptable equal growth in therapeutic management of AML in the elderly; this is in sharp contrast to the increase in successful therapies for leukemia in younger patients. Therefore, a focus on the understanding of the biology of aging in the hematopoietic system, the development of appropriate research models, and new therapeutic approaches are urged.

Targeting Immune Signaling Pathways in Clonal Hematopoiesis

BACKGROUND

Myeloid neoplasms are a diverse group of malignant diseases with different entities and numerous patho-clinical features. They arise from mutated clones of hematopoietic stem- and progenitor cells which expand by outperforming their normal counterparts. The intracellular signaling profile of cancer cells is the sum of genetic, epigenetic and microenvironmental influences, and the multiple interconnections between different signaling pathways make pharmacological targeting complicated.

OBJECTIVE

To present an overview of known somatic mutations in myeloproliferative neoplasms (MPN), myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) and the inflammatory signaling pathways affected by them, as well as current efforts to therapeutically modulate this aberrant inflammatory signaling.

METHODS

In this review, we extensively reviewed and compiled salient information with ClinicalTrials.gov as our source on ongoing studies, and PubMed as our authentic bibliographic source, using a focused review question.

RESULTS

Mutations affecting immune signal transduction are present to varying extents in clonal myeloid diseases. While MPN are dominated by a few common mutations, a multitude of different genes can be mutated in MDS and AML. Mutations can also occur in asymptomatic persons, a finding called clonal hematopoiesis of indeterminate potential (CHIP). Mutations in FLT3, JAK, STAT, CBL and RAS can lead to aberrant immune signaling. Protein kinase inhibitors are entering the clinic and are extensively investigated in clinical trials in MPN, MDS and AML.

CONCLUSION

In summary, this article summarizes recent research on aberrant inflammatory signaling in clonal myeloid diseases and the clinical therapeutic potential of modulation of signal transduction and effector proteins in the affected pathways.

Genetic alterations in 47 patients with a novel myelodysplastic syndrome diagnosis at a single center

At least one mutation is present in 70–80% of patients with myelodysplastic syndrome (MDS). Genetic alterations and other molecular biological markers have been included in the diagnostic and treatment guidelines for MDS. The aim of the present study was to analyze the association between genetic alterations and clinicopathological features among 47 Chinese patients with a novel diagnosis of MDS using a next-generation sequencing approach. The results indicated that from the 47 patients, 66.0% had genetic alterations. Furthermore, seven genes, U2 small nuclear RNA auxiliary factor 1 (23.4%), splicing factor 3b subunit (12.8%), ASXL transcriptional regulator 1 (10.6%), tet methylcytosine dioxygenase 2 (8.5%), BCL6 corepressor (8.5%), TP53 (8.5%) and DNA methyltransferase 3^α (6.4%), indicated a higher prevalence of alterations in >5% of patients. Among the 16 (51.6%) patients with ≥2 mutations, 12 (75%) had mutations in different genetic functional groups. Variant allele frequencies in signaling pathways were generally low, suggesting that mutations in the corresponding genes were acquired relatively late during the evolution of the leukemic clones. The mutation prevalence rates of Janus kinase 2 and SH2B adaptor protein 3 were significantly higher in the MDS unclassified group and in the very high-risk groups with a karyotype as a prognostic indicator, respectively (both P<0.05). The mutation prevalence rates of SET binding protein 1 and enhancer of zeste 2 polycomb repressive complex 2 subunit were significantly higher in the high-risk group (both P<0.05). In summary, 66.0% of the 47 patients with a novel MDS diagnosis had a genetic mutation as detected by 127-target gene next-generation sequencing. The results for the genetic alterations in the present study will supplement the database of patients with MDS in China.

Spanish Guidelines for the use of targeted deep sequencing in myelodysplastic syndromes and chronic myelomonocytic leukaemia

The landscape of medical sequencing has rapidly changed with the evolution of next generation sequencing (NGS). These technologies have contributed to the molecular characterization of the myelodysplastic syndromes (MDS) and chronic myelomonocytic leukaemia (CMML), through the identification of recurrent gene mutations, which are present in >80% of patients. These mutations contribute to a better classification and risk stratification of the patients. Currently, clinical laboratories include NGS genomic analyses in their routine clinical practice, in an effort to personalize the diagnosis, prognosis and treatment of MDS and CMML. NGS technologies have reduced the cost of large-scale sequencing, but there are additional challenges involving the clinical validation of these technologies, as continuous advances are constantly being made. In this context, it is of major importance to standardize the generation, analysis, clinical interpretation and reporting of NGS data. To that end, the Spanish MDS Group (GESMD) has expanded the present set of guidelines, aiming to establish common quality standards for the adequate implementation of NGS and clinical interpretation of the results, hoping that this effort will ultimately contribute to the benefit of patients with myeloid malignancies.

The evolving role of next generation sequencing in myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are clonal haematological disorders characterized by haematopoietic cell dysplasia, peripheral blood cytopenias, and a predisposition for developing acute myeloid leukaemia (AML). Cytogenetics have historically been important in diagnosis and prognosis in MDS, but the growing accessibility of next generation sequencing (NGS) has led to growing research in the roles of molecular genetic variation on clinical decision-making in these disorders. Multiple genes have been previously studied and found to be associated with specific outcomes or disease types within MDS and knowledge of mutations in these genes provides insight into previously defined MDS subtypes. Knowledge of these mutations also informs development of novel therapies in the treatment of MDS. The precise role of NGS in the diagnosis, prognosis and monitoring of MDS remains unclear but the improvements in NGS technology and accessibility affords clinicians an additional practice tool to provide the best care for patients.

Cell-lineage level-targeted sequencing to identify acute myeloid leukemia with myelodysplasia-related changes

Acute myeloid leukemia (AML) is a clonal myeloid neoplasm that typically arises de novo; however, some cases evolve from a preleukemic state, such as myelodysplastic syndrome (MDS). Such secondary AMLs and those with typical MDS-related clinical features are known as AMLs with myelodysplasia-related changes (AML-MRC). Because patients with AML-MRC have poor prognosis, more accurate diagnostic approaches are required. In this study, we performed targeted sequencing of 54 genes in 3 cell populations (granulocyte, blast, and T-cell fractions) using samples from 13 patients with MDS, 16 patients with clinically diagnosed AML-MRC, 4 patients with suspected AML-MRC but clinically diagnosed as AML not otherwise specified (AML-NOS), and 11 patients with de novo AML. We found that overlapping mutations, defined as those shared at least by the blast and granulocyte fractions, were significantly enriched in patients with MDS and AML-MRC, including those with suspected AML-MRC, indicating a substantial history of clonal hematopoiesis. In contrast, blast-specific nonoverlapping mutations were significantly enriched in patients with de novo AML. Furthermore, the presence of overlapping mutations, excluding DNMT3A, TET2, and ASXL1, effectively segregated patients with MDS and AML-MRC or suspected AML-MRC from patients with de novo AML. Additionally, the presence of ≥3 mutations in the blast fraction was useful for distinguishing patients with AML-MRC from those with MDS. In conclusion, our approach is useful for classifying clinically diagnosable AML-MRC and identifying clinically diagnosed AML-NOS as latent AML-MRC. Additional prospective studies are needed to confirm the utility of this approach.

FF-10501 induces caspase-8-mediated apoptotic and endoplasmic reticulum stress-mediated necrotic cell death in hematological malignant cells

FF-10501 is a novel inhibitor of inosine monophosphate dehydrogenase (IMPDH). Clinical trials of FF-10501 for myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML) are currently being conducted in the United States. Although it has been shown that FF-10501 induces apoptosis in hematological malignant cells, the intracellular mechanisms of this effect have not been characterized. We conducted an in vitro study to elucidate the mechanisms of FF-10501-induced cell death using 12 hematological malignant cell lines derived from myeloid and lymphoid malignancies. FF-10501 suppressed the growth of each cell line in a dose-dependent manner. However, the clinically relevant dose (40 μM) of FF-10501 induced cell death in three cell lines (MOLM-13, OCI-AML3, and MOLT-3). Investigation of the cell death mechanism suggested that FF-10501 induces both apoptotic and necrotic cell death. FF-10501-induced apoptosis was mediated by caspase-8 activation followed by activation of the mitochondrial pathway in MOLM-13 and MOLT-3 cells. FF-10501 induced necrotic cell death via endoplasmic reticulum stress in OCI-AML3 cells. The present study is the first to identify intracellular pathways involved in FF-10501-induced cell death.

[Outcomes and prognostic factors of myelodysplastic syndrome patients with allogeneic hematopoietic stem cell transplantation]

Objective: To evaluate the outcomes and prognostic factors of myelodysplasia syndrome (MDS) patients who received allogeneic hematopoietic stem cell transplantation (allo-HSCT) . Methods: 165 cases of MDS who underwent allo-HSCT from Jan. 2010 to Mar. 2018 were analyzed retrospectively, focusing on the overall survival (OS) , disease free survival (DFS) , relapse, non-relapse mortality (NRM) and their related risk factors. Results: Of all the 165 cases, 105 were male and 60 were female. The 3-year OS and DFS rate were 72.5% (95%CI 64.9%-80.1%) and 67.4% (95%CI 59.17%-75.63%) , respectively. The 3-year cumulative incidence of relapse and NRM were 12.11% (95%CI 7.03%-18.65%) and 20.44% (95%CI 14.15%-27.56%) , respectively. HCT-comorbidity index (P=0.042, HR=2.094, 95%CI 1.026-4.274) was identified as independent risk factor for OS by the multivariate analysis. Intensive chemotherapy before HSCT or hypomethylation agents treatment had no effects on OS[ (67.0±7.5) %vs (57.7±10.9) %, χ(2)=0.025, P=0.874]. Conclusions: allo-HSCT is a promising means for MDS, and NRM is the major cause of treatment failure. MDS with refractory anemia with excess blasts and secondary acute myeloid leukemia patients may not benefit from intensive chemotherapy or hypomethylation agents treatment before HSCT.

Myelodysplastic Syndromes: Laboratory Workup in the Context of New Concepts and Classification Criteria

PURPOSE OF REVIEW

This review provides a comprehensive update of myelodysplastic syndromes (MDS) and their diagnostic criteria, with emphasis on novel concepts and state-of-the-art laboratory workup, including multiparameter/multicolor flow cytometry, chromosome analysis, and mutation profiling.

RECENT FINDINGS

Recent advances in genetics and molecular technologies have provided unprecedented insights into the pathogenic mechanisms and genomic landscape of MDS and its precursor lesions. This has resulted in revised diagnostic criteria in the World Health Organization (WHO) classification and proposed new terminology for early lesions such as clonal hematopoiesis of indeterminate potential (CHIP). Against this landscape, a thorough understanding of the advantages and limitations of laboratory tests employed in the evaluation of patients with cytopenia has gained unprecedented importance. Healthcare providers involved in the care of patients with hematologic diseases should be aware of the intricacies of laboratory workup of such patients, particularly in view of the novel concepts and classification criteria of MDS.

Signal Transduction in Ribosome Biogenesis: A Recipe to Avoid Disaster

Energetically speaking, ribosome biogenesis is by far the most costly process of the cell and, therefore, must be highly regulated in order to avoid unnecessary energy expenditure. Not only must ribosomal RNA (rRNA) synthesis, ribosomal protein (RP) transcription, translation, and nuclear import, as well as ribosome assembly, be tightly controlled, these events must be coordinated with other cellular events, such as cell division and differentiation. In addition, ribosome biogenesis must respond rapidly to environmental cues mediated by internal and cell surface receptors, or stress (oxidative stress, DNA damage, amino acid depletion, etc.). This review examines some of the well-studied pathways known to control ribosome biogenesis (PI3K-AKT-mTOR, RB-p53, MYC) and how they may interact with some of the less well studied pathways (eIF2α kinase and RNA editing/splicing) in higher eukaryotes to regulate ribosome biogenesis, assembly, and protein translation in a dynamic manner.

Binimetinib, a novel MEK1/2 inhibitor, exerts anti-leukemic effects under inactive status of PI3Kinase/Akt pathway

A MEK1/2 inhibitor, binimetinib is promising as a therapeutic agent for malignant melanoma with N-RAS mutation. We examined in vitro effects of binimetinib on 10 human myeloid/lymphoid leukemia cell lines, and found that three of five cell lines with N-RAS mutation and one of five without N-RAS mutation were responsive to treatment with binimetinib. Binimetinib inhibited cell growth mainly by inducing G₁ arrest and this action mechanism was assisted by gene set enrichment analysis. To identify signaling pathways associated with binimetinib response, we examined the status of MAP kinase/ERK and PI3Kinase/Akt pathways. The basal levels of phosphorylated ERK and Akt varied between the cell lines, and the amounts of phosphorylated ERK and Akt appeared to be reciprocal of each other. Interestingly, most of the binimetinib-resistant cell lines revealed strong Akt phosphorylation compared with binimetinib-sensitive ones. The effect of binimetinib may not be predicted by the presence/absence of N-RAS mutation, but rather by Akt phosphorylation status. Moreover, combination of binimetinib with a PI3K/Akt inhibitor showed additive growth-suppressive effects. These results suggest that binimetinib shows potential anti-leukemic effects and the basal level of phosphorylated Akt might serve as a biomarker predictive of therapeutic effect.

Secreted nuclear protein DEK regulates hematopoiesis through CXCR2 signaling

The nuclear protein DEK is an endogenous DNA-binding chromatin factor regulating hematopoiesis. DEK is one of only 2 known secreted nuclear chromatin factors, but whether and how extracellular DEK regulates hematopoiesis is not known. We demonstrated that extracellular DEK greatly enhanced ex vivo expansion of cytokine-stimulated human and mouse hematopoietic stem cells (HSCs) and regulated HSC and hematopoietic progenitor cell (HPC) numbers in vivo and in vitro as determined both phenotypically (by flow cytometry) and functionally (through transplantation and colony formation assays). Recombinant DEK increased long-term HSC numbers and decreased HPC numbers through a mechanism mediated by the CXC chemokine receptor CXCR2 and heparan sulfate proteoglycans (HSPGs) (as determined utilizing Cxcr2-/- mice, blocking CXCR2 antibodies, and 3 different HSPG inhibitors) that was associated with enhanced phosphorylation of ERK1/2, AKT, and p38 MAPK. To determine whether extracellular DEK required nuclear function to regulate hematopoiesis, we utilized 2 mutant forms of DEK: one that lacked its nuclear translocation signal and one that lacked DNA-binding ability. Both altered HSC and HPC numbers in vivo or in vitro, suggesting the nuclear function of DEK is not required. Thus, DEK acts as a hematopoietic cytokine, with the potential for clinical applicability.