Targeted deep sequencing improves outcome stratification in chronic myelomonocytic leukemia with low risk cytogenetic features

Myelodysplastic Syndrome: Clinical Characteristics and Significance of Preclinically Detecting Biallelic Mutations in the TET2 Gene

Myelodysplastic syndrome (MDS) is a clonal disease derived from hematopoietic stem cells, characterized by ineffective hematopoiesis (resulting in peripheral blood cytopenia) and an increased risk of transformation into acute myeloid leukemia. MDS is caused by a complex combination of genetic mutations resulting in a heterogeneous genotype. Genetic studies have identified a set of aberrations that play a central role in the pathogenesis of MDS. In this article, we present a clinical case of MDS transformation into acute myeloid leukemia in the context of two cell lines exhibiting morphological, immunophenotypic, and dysmyelopoiesis markers and the presence of two heterozygous mutations in the TET2 gene.

Kidney and Urinary Tract Involvement in Chronic Myelomonocytic Leukemia

Chronic myelomonocytic leukemia (CMML) is a hematologic malignancy affecting the bone marrow and resulting in peripheral blood monocytosis. Kidney and urinary tract involvement is common and can present dramatically with life-threatening consequences. Kidney involvement can be the result of direct or indirect mechanisms, including prerenal azotemia, glomerular disease, tubulointerstitial involvement, and renovascular disorders. Urinary tract involvement, electrolyte and acid-base disorders, as well as nephrotoxicity from treatment of the disorder can also occur. Given this multifactorial pathogenesis involving several mechanisms concomitantly, nephrologists must exercise heightened awareness and maintain a low threshold for kidney biopsy. There is a pressing need for future research endeavors to elucidate and target the manifestations of CMML that involve the kidneys with the ultimate goal of augmenting overall prognosis and therapeutic outcomes.

Clinical and prognostic profile of SRSF2 and related spliceosome mutations in patients with acute myeloid leukemia

BACKGROUND

Mutations in splicing factor (SF) genes are frequently detected in myelodysplastic syndrome, but their clinical and prognostic relevance in acute myeloid leukemia (AML) have rarely been reported.

METHODS

A total of 368 newly diagnosed non-M3 AML patients were included in this study. Next generation sequencing including four SF genes was performed on the genomicDNA. The clinical features and survival were analyzed using statistical analysis.

RESULTS

We found that 64 of 368 patients harbored SF mutations. The SF mutations were much more frequently found in older or male patients. SRSF2 mutations were shown obviously co-existed with IDH2 mutation. The level of measurable residual disease after first chemotherapy was higher in SF-mutated patients compared to that in SF-wild patients, while the complete remission rate was significantly decreased. And the overall survival of SF-mutated patients was shorter than that of SF-wild patients. Moreover, our multivariable analysis suggests that the index of male, Kit mutation or ZRSR2 mutation was the independent risk factor for overall survival. SRSF2mut was associated with older age, higher proportion of peripheral blasts or abnormal cell proportion by flow cytometry.

CONCLUSION

SF mutation is a distinct subgroup of AML frequently associated with clinic-biological features and poor outcome. SRSF2mut could be potential targets for novel treatment in AML.

Comprehensive Validation of Diagnostic Next-Generation Sequencing Panels for Acute Myeloid Leukemia Patients

Next-generation sequencing has greatly advanced the molecular diagnostics of malignant hematological diseases and provides useful information for clinical decision making. Studies have shown that certain mutations are associated with prognosis and have a direct impact on treatment of affected patients. Therefore, reliable detection of pathogenic variants is critically important. In this study, we aimed to compare four sequencing panels with different characteristics, from number of genes covered to technical aspects of library preparation and data analysis workflows, to find the panel with the best clinical utility for myeloid neoplasms with a special focus on acute myeloid leukemia. Using the Acrometrix Oncology Hotspot Control DNA and DNA from acute myeloid leukemia patients, we evaluated panel performance in terms of coverage, precision, recall, and reproducibility and tested different bioinformatics tools that can be used for the evaluation of any next-generation sequencing panel. Taken together, our results support the reliability of the Acrometrix Oncology Hotspot Control to validate and compare sequencing panels for hematological diseases and show which panel-software combination (platform) has the best performance.

The utility of a myeloid mutation panel for the diagnosis of myelodysplastic syndrome and myelodysplastic/myeloproliferative neoplasm

INTRODUCTION

The diagnosis of myelodysplastic syndromes (MDS) and myelodysplastic/myeloproliferative neoplasms (MDS/MPN) is based on morphology and cytogenetics/FISH findings per 2017 WHO classification. With rare exceptions, somatic mutations have not been incorporated as the diagnostic criteria.

METHODS

We analyzed the utility of mutational analysis with a targeted 54-gene or 40-gene next-generation sequencing (NGS) panel in the diagnosis of MDS and MDS/MPN.

RESULTS

We retrospectively collected 92 patients who presented with unexplained cytopenia with or without cytosis, including 32 low-grade MDS (MDS-L), 18 high-grade MDS (MDS-H), 5 therapy-related MDS (MDS-TR), 19 MDS/MPN, and 18 negative cases. Of 92 patients, 197 somatic mutations involving 38 genes were detected and had variant allele frequency (VAF) ranging from 3% to 99%. The most common mutated genes were TET2, ASXL1, RUNX1, TP53, SRSF2, and SF3B1. MDS-L, MDS-H, MDS-TR, and MDS/MPN showed an average number of somatic mutations with a mean VAF of 1.9/33%, 2.6/30%, 2/36%, and 4/41%, respectively. SF3B1 mutations were exclusively observed in MDS-L and MDS/MPN. TP53 gene mutations were more frequently seen in MDS-H and MDS-TR. Among 34 patients with a diagnosis of MDS or MDS/MPN with normal cytogenetics, 31 patients (91%) had at least 1 mutation and 24 patients (71%) had ≥2 mutations with ≥10% VAF.

CONCLUSION

A myeloid mutational panel provides additional evidence of clonality besides cytogenetics/FISH studies in the diagnosis of cytopenia with or without cytosis. Two or more mutations with ≥10% VAF highly predicts MDS and MDS/MPN with a positive predictive value of 100%.

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.

Clinical and Molecular Approach to Adult-Onset, Neoplastic Monocytosis

PURPOSE OF REVIEW

In this review, we provide a comprehensive and contemporary understanding of malignant monocytosis and provide a framework by which the appropriate diagnosis with malignant monocytosis can be rendered.

RECENT FINDINGS

Increasing data support the use of molecular data to refine the diagnostic approach to persistent monocytosis. The absence of a TET2, SRSF2, or ASXL1 mutation has ≥ 90% negative predictive value for a diagnosis of CMML. These data may also reliably differentiate chronic myelomonocytic leukemia, the malignancy that is most associated with mature monocytosis, from several other diseases that can be associated with typically a lesser degree of monocytosis. These include acute myelomonocytic leukemia, acute myeloid leukemia with monocytic differentiation, myelodysplastic syndromes, and myeloproliferative neoplasms driven by BCR-ABL1, PDGFRA, PDGFRB, or FGFR1 rearrangements or PCM1-JAK2 fusions among other rarer aberrations. The combination of monocyte partitioning with molecular data in patients with persistent monocytosis may increase the predictive power for the ultimate development of CMM but has not been prospectively validated. Many conditions, both benign and malignant, can be associated with an increase in mature circulating monocytes. After reasonably excluding a secondary or reactive monocytosis, there should be a concern for and investigation of malignant monocytosis, which includes hematopathologic review of blood and marrow tissues, flow cytometric analysis, and cytogenetic and molecular studies to arrive at an appropriate diagnosis.

Risk-Adapted, Individualized Treatment Strategies of Myelodysplastic Syndromes (MDS) and Chronic Myelomonocytic Leukemia (CMML)

Myelodysplastic syndrome (MDS) and chronic myelomonocytic leukemia (CMML) are two distinct blood cancers with a variable clinical symptom burden and risk of progression to acute myeloid leukemia. Management decisions should be guided by individual patient and disease characteristics and based on validated risk stratification tools. While supportive care with red blood cell transfusions, erythropoiesis-stimulating agents, and iron chelation remains the mainstay of therapy for lower-risk (LR)-MDS patients, luspatercept has recently been approved for transfusion-dependent anemic LR-MDS patients ending a decade without any new drug approvals for MDS. For higher-risk patients, allogeneic hematopoietic cell transplant (allo-HCT) remains the only curative therapy for both MDS and CMML but most patients are not eligible for allo-HCT. For those patients, the hypomethylating agents (HMA) azacitidine and decitabine remain standard of care with azacitidine being the only agent that has shown an overall survival benefit in randomized trials. Although early results from novel molecularly driven agents such as IDH1/2 inhibitors, venetoclax, magrolimab, and APR-246 for MDS as well as tagraxofusp, tipifarnib, and lenzilumab for CMML appear encouraging, confirmatory randomized trials must be completed to fully assess their safety and efficacy prior to routine clinical use. Herein, we review the current management of MDS and CMML and conclude with a critical appraisal of novel therapies and general trends in this field.

Phenotypic characterization of leukemia-initiating stem cells in chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia (CMML) is a stem cell-derived neoplasm characterized by dysplasia, uncontrolled expansion of monocytes, and substantial risk to transform to secondary acute myeloid leukemia (sAML). So far, little is known about CMML-initiating cells. We found that leukemic stem cells (LSC) in CMML reside in a CD34⁺/CD38^- fraction of the malignant clone. Whereas CD34⁺/CD38^- cells engrafted NSGS mice with overt CMML, no CMML was produced by CD34⁺/CD38⁺ progenitors or the bulk of CD34^- monocytes. CMML LSC invariably expressed CD33, CD117, CD123 and CD133. In a subset of patients, CMML LSC also displayed CD52, IL-1RAP and/or CLL-1. CMML LSC did not express CD25 or CD26. However, in sAML following CMML, the LSC also expressed CD25 and high levels of CD114, CD123 and IL-1RAP. No correlations between LSC phenotypes, CMML-variant, mutation-profiles, or clinical course were identified. Pre-incubation of CMML LSC with gemtuzumab-ozogamicin or venetoclax resulted in decreased growth and impaired engraftment in NSGS mice. Together, CMML LSC are CD34⁺/CD38^- cells that express a distinct profile of surface markers and target-antigens. During progression to sAML, LSC acquire or upregulate certain cytokine receptors, including CD25, CD114 and CD123. Characterization of CMML LSC should facilitate their enrichment and the development of LSC-eradicating therapies.

Large-Scale Identification of Clonal Hematopoiesis and Mutations Recurrent in Blood Cancers

Clonal hematopoiesis of indeterminate potential (CHIP) is characterized by detectable hematopoietic-associated gene mutations in a person without evidence of hematologic malignancy. We sought to identify additional cancer-presenting mutations useable for CHIP detection by performing a data mining analysis of 48 somatic mutation studies reporting mutations at diagnoses of 7,430 adult and pediatric patients with hematologic malignancies. Following extraction of 20,141 protein-altering mutations, we identified 434 significantly recurrent mutation hotspots, 364 of which occurred at loci confidently assessable for CHIP. We then performed an additional large-scale analysis of whole exome sequencing data from 4,538 persons belonging to three non-cancer cohorts for clonal mutations. We found the combined cohort prevalence of CHIP with mutations identical to those reported at blood cancer mutation hotspots to be 1.8%, and that some of these CHIP mutations occurred in children. Our findings may help to improve CHIP detection and pre-cancer surveillance for both children and adults.

Analysis of Intratumoral Heterogeneity in Myelodysplastic Syndromes with Isolated del(5q) Using a Single Cell Approach

Simple Summary

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematopoietic stem cell malignancies characterized by ineffective differentiation of one or more bone marrow cell lineages. Only 50% of patients with de novo MDS will be found to have cytogenetic abnormalities, of which del(5q) is the most common. In 10% of MDS cases, del(5q) is found as a sole abnormality. In this work, a single cell approach was used to analyze intratumoral heterogeneity in four patients with MDS with isolated del(5q). We were able to observe that an ancestral event in one patient can appear as a secondary hit in another one, thus reflecting the high intratumoral heterogeneity in MDS with isolated del(5q) and the importance of patient-specific molecular characterization.

Abstract

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematological diseases. Among them, the most well characterized subtype is MDS with isolated chromosome 5q deletion (MDS del(5q)), which is the only one defined by a cytogenetic abnormality that makes these patients candidates to be treated with lenalidomide. During the last decade, single cell (SC) analysis has emerged as a powerful tool to decipher clonal architecture and to further understand cancer and other diseases at higher resolution level compared to bulk sequencing techniques. In this study, a SC approach was used to analyze intratumoral heterogeneity in four patients with MDS del(5q). Single CD34+CD117+CD45+CD19- bone marrow hematopoietic stem progenitor cells were isolated using the C1 system (Fluidigm) from diagnosis or before receiving any treatment and from available follow-up samples. Selected somatic alterations were further analyzed in SC by high-throughput qPCR (Biomark HD, Fluidigm) using specific TaqMan assays. A median of 175 cells per sample were analyzed. Inferred clonal architectures were relatively simple and either linear or branching. Similar to previous studies based on bulk sequencing to infer clonal architecture, we were able to observe that an ancestral event in one patient can appear as a secondary hit in another one, thus reflecting the high intratumoral heterogeneity in MDS del(5q) and the importance of patient-specific molecular characterization.

Moving towards a uniform risk stratification system in CMML - How far are we?

Many prognostic scoring systems have been developed for chronic myelomonocytic leukemia (CMML). Although these efforts have been informative, no single model has been considered the consensus for CMML prognostication and all models are only moderately prognostic. CMML clinical models utilize mainly hematology and morphology parameters to estimate risk. A better understanding of cytogenetics and the genomic landscape of CMML have resulted in integrated risk models such as CMML Prognostic Scoring System (CPSS)-Mol and Mayo Molecular that may provide better prognostic accuracy for an individual patient. For example, frameshift/nonsense ASXL1 mutations have been consistently shown to confer inferior outcomes leading to its incorporation into some of the major risk classification systems. Prognostication in the setting of therapeutic interventions such as hypomethylating agents and allogeneic hematopoietic cell transplantation have also garnered considerable interest. Despite having many validated risk models available, not a single system is universally adopted. Herein, we will provide an overview of how these systems evolved and progress toward a uniform system.

Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-U): More than just a "catch-all" term?

The clinicopathology of MDS and MPN are not mutually exclusive and for this reason the category of myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) exists. Several sub-entities have been included under the MDS/MPN umbrella, including MDS/MPN-unclassifiable (MDS/MPN-U) for those cases whose morphologic and clinical phenotype do not meet criteria to be classified as any other MDS/MPN sub-entity. Though potentially regarded as a wastebasket diagnosis, since its integration into myeloid disease classification, MDS/MPN-U has been refined with increasing understanding of the mutational and genomic events that drive particular clinicopathologic phenotypes, even within MDS/MPN-U. The prototypical example is the identification of SF3B1 mutations and its durable association with MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), an entity previously buried within, but now a separate category outside of MDS/MPN-U. Continued and enhanced study of those entities under MDS/MPN-U, a perhaps provisional category itself, is likely to progressively identify commonality between many "unclassifiables" to establish a new classifiable diagnosis.

Engaging chromatin: PRC2 structure meets function

Polycomb repressive complex 2 (PRC2) is a key epigenetic multiprotein complex involved in the regulation of gene expression in metazoans. PRC2 is formed by a tetrameric core that endows the complex with histone methyltransferase activity, allowing it to mono-, di- and tri-methylate histone H3 on lysine 27 (H3K27me1/2/3); H3K27me3 is a hallmark of facultative heterochromatin. The core complex of PRC2 is bound by several associated factors that are responsible for modulating its targeting specificity and enzymatic activity. Depletion and/or mutation of the subunits of this complex can result in severe developmental defects, or even lethality. Furthermore, mutations of these proteins in somatic cells can be drivers of tumorigenesis, by altering the transcriptional regulation of key tumour suppressors or oncogenes. In this review, we present the latest results from structural studies that have characterised PRC2 composition and function. We compare this information with data and literature for both gain-of function and loss-of-function missense mutations in cancers to provide an overview of the impact of these mutations on PRC2 activity.

Chronic Myelomonocytic Leukemia With Fibrosis Is a Distinct Disease Subset With Myeloproliferative Features and Frequent JAK2 p.V617F Mutations

A subset of patients with chronic myelomonocytic leukemia (CMML) presents with significance myelofibrosis. In myelodysplastic syndromes, significant myelofibrosis has been associated with adverse outcomes and p53 dysregulation. However, in CMML the clinical and molecular correlates of significant myelofibrosis at presentation remain poorly understood. From a cohort of 651 CMML patients, we identified retrospectively 20 (3.1%) cases with moderate to severe reticulin fibrosis (CMML-F) detected at diagnosis, and we compared them to CMML patients without fibrosis (n=631) seen during the same period. Patients with CMML-F had a median age of 69.8 years (range, 24.8 to 91.2 y) and most (13; 65%) were men. Patients with CMML-F differed significantly from other CMML patients across the following parameters: white blood count, absolute monocyte count, serum lactate dehydrogenase level, splenomegaly, and bone marrow blast percentage. Notably, the frequency of JAK2 p.V617F mutation was higher in CMML-F patients compared with other CMML patients (P<0.001). Most CMML-F patients (12/20; 60%) had myeloproliferative CMML. Dysregulation of p53 was uncommon in CMML-F. CMML-F patients tended to have a shorter median overall survival compared with other CMML patients (P=0.079). Multivariate analysis using the Cox proportional hazards model showed an independent association between CMML-F and overall survival (P=0.047). In summary, unlike typical CMML, CMML-F is commonly associated with JAK2 p.V617F. The high frequency of myeloproliferative features and JAK2 p.V617F mutation, and the low frequency of p53 dysregulation, suggest that fibrosis in the context of CMML has a different pathogenesis from that previously reported in myelodysplastic syndrome.

Update on the pathologic diagnosis of chronic myelomonocytic leukemia

The diagnostic criteria for chronic myelomonocytic leukemia were recently revised in the 2016 World Health Organization classification update and include new and revised subtypes. In addition, molecular genetic studies have provided new insights into the prognosis and diagnosis of this myeloid neoplasm. This review summarizes the 2016 changes to the diagnostic criteria, discusses potential future changes that may impact diagnosis and provides an overview of recent advances in the diagnosis and prognosis determination of chronic myelomonocytic leukemia.

Proposed diagnostic criteria for classical chronic myelomonocytic leukemia (CMML), CMML variants and pre-CMML conditions

Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm characterized by dysplasia, abnormal production and accumulation of monocytic cells and an elevated risk of transforming into acute leukemia. Over the past two decades, our knowledge about the pathogenesis and molecular mechanisms in CMML has increased substantially. In parallel, better diagnostic criteria and therapeutic strategies have been developed. However, many questions remain regarding prognostication and optimal therapy. In addition, there is a need to define potential pre-phases of CMML and special CMML variants, and to separate these entities from each other and from conditions mimicking CMML. To address these unmet needs, an international consensus group met in a Working Conference in August 2018 and discussed open questions and issues around CMML, its variants, and pre-CMML conditions. The outcomes of this meeting are summarized herein and include diag nostic criteria and a proposed classification of pre-CMML conditions as well as refined minimal diagnostic criteria for classical CMML and special CMML variants, including oligomonocytic CMML and CMML associated with systemic mastocytosis. Moreover, we propose diagnostic standards and tools to distinguish between 'normal', pre-CMML and CMML entities. These criteria and standards should facilitate diagnostic and prognostic evaluations in daily practice and clinical studies in applied hematology.

Clonal Hematopoiesis with Oncogenic Potential (CHOP): Separation from CHIP and Roads to AML

The development of leukemia is a step-wise process that is associated with molecular diversification and clonal selection of neoplastic stem cells. Depending on the number and combinations of lesions, one or more sub-clones expand/s after a variable latency period. Initial stages may develop early in life or later in adulthood and include premalignant (indolent) stages and the malignant phase, defined by an acute leukemia. We recently proposed a cancer model in which the earliest somatic lesions are often age-related early mutations detectable in apparently healthy individuals and where additional oncogenic mutations will lead to the development of an overt neoplasm that is usually a preleukemic condition such as a myelodysplastic syndrome. These neoplasms may or may not transform to overt acute leukemia over time. Thus, depending on the type and number of somatic mutations, clonal hematopoiesis (CH) can be divided into CH with indeterminate potential (CHIP) and CH with oncogenic potential (CHOP). Whereas CHIP mutations per se usually create the molecular background of a neoplastic process, CHOP mutations are disease-related or even disease-specific lesions that trigger differentiation and/or proliferation of neoplastic cells. Over time, the acquisition of additional oncogenic events converts preleukemic neoplasms into secondary acute myeloid leukemia (sAML). In the present article, recent developments in the field are discussed with a focus on CHOP mutations that lead to distinct myeloid neoplasms, their role in disease evolution, and the impact of additional lesions that can drive a preleukemic neoplasm into sAML.

Heterogeneous expression of cytokines accounts for clinical diversity and refines prognostication in CMML

Chronic myelomonocytic leukemia (CMML) is a clinically heterogeneous neoplasm in which JAK2 inhibition has demonstrated reductions in inflammatory cytokines and promising clinical activity. We hypothesize that annotation of inflammatory cytokines may uncover mutation-independent cytokine subsets associated with novel CMML prognostic features. A Luminex cytokine profiling assay was utilized to profile cryopreserved peripheral blood plasma from 215 CMML cases from three academic centers, along with center-specific, age-matched plasma controls. Significant differences were observed between CMML patients and healthy controls in 23 out of 45 cytokines including increased cytokine levels in IL-8, IP-10, IL-1RA, TNF-α, IL-6, MCP-1/CCL2, hepatocyte growth factor (HGF), M-CSF, VEGF, IL-4, and IL-2RA. Cytokine associations were identified with clinical and genetic features, and Euclidian cluster analysis identified three distinct cluster groups associated with important clinical and genetic features in CMML. CMML patients with decreased IL-10 expression had a poor overall survival when compared to CMML patients with elevated expression of IL-10 (P = 0.017), even when adjusted for ASXL1 mutation and other prognostic features. Incorporating IL-10 with the Mayo Molecular Model statistically improved the prognostic ability of the model. These established cytokines, such as IL-10, as prognostically relevant and represent the first comprehensive study exploring the clinical implications of the CMML inflammatory state.

DNA methylation profile in chronic myelomonocytic leukemia associates with distinct clinical, biological and genetic features

Chromosomal abnormalities are detected in 20-30% of patients with chronic myelomonocytic leukemia (CMML) and correlate with prognosis. On the mutation level, disruptive alterations are particularly frequent in chromatin regulatory genes. However, little is known about the consequential alterations in the epigenetic marking of the genome. Here, we report the analysis of genomic DNA methylation patterns of 64 CMML patients and 10 healthy controls, using a DNA methylation microarray focused on promoter regions. Differential methylation analysis between patients and controls allowed us to identify abnormalities in DNA methylation, including hypermethylation of specific genes and large genome regions with aberrant DNA methylation. Unsupervised hierarchical cluster analysis identified two main clusters that associated with the clinical, biological, and genetic features of patients. Group 1 was enriched in patients with adverse clinical and biological characteristics and poorer overall and progression-free survival. In addition, significant differences in DNA methylation were observed between patients with low risk and intermediate/high risk karyotypes and between TET2 mutant and wild type patients. Taken together, our results demonstrate that altered DNA methylation patterns reflect the CMML disease state and allow to identify patient groups with distinct clinical features.

Oligomonocytic chronic myelomonocytic leukemia (chronic myelomonocytic leukemia without absolute monocytosis) displays a similar clinicopathologic and mutational profile to classical chronic myelomonocytic leukemia

Chronic myelomonocytic leukemia is characterized by persistent absolute monocytosis (≥1 × 10⁹/l) in the peripheral blood and dysplasia in ≥1 lineages. In the absence of dysplasia, an acquired clonal genetic abnormality is required or causes for reactive monocytosis have to be excluded. Oligomonocytic chronic myelomonocytic leukemia showing increased monocytes but no absolute monocytosis in the peripheral blood occurs occasionally. These cases are likely classified as myelodysplastic syndrome or myelodysplastic/myeloproliferative neoplasm, unclassifiable. A subset eventually develop overt chronic myelomonocytic leukemia. Better characterization of oligomonocytic chronic myelomonocytic leukemia is essential since the distinction between chronic myelomonocytic leukemia and myelodysplastic syndrome is clinically relevant. We identified 44 cases of oligomonocytic chronic myelomonocytic leukemia (≥10% peripheral blood monocytes with absolute monocyte count of 0.5-1 × 10⁹/l) and 28 consecutive chronic myelomonocytic leukemia controls. Clinicopathologic features were compared and mutation analysis was performed. Oligomonocytic chronic myelomonocytic leukemia patients were significantly younger (median age of 65 vs 72). They had lower WBC and absolute neutrophil count, while the monocyte percentage, hemoglobin and platelet counts were similar in the two groups. The myeloid to erythroid ratio was predominantly decreased or normal, compared with the characteristic increase in chronic myelomonocytic leukemia (P=0.006). 38% of patients progressed to overt chronic myelomonocytic leukemia (median: 12 months). The overall percentage of mutations was significantly lower in oligomonocytic chronic myelomonocytic leukemia. However, the most frequent mutations in both groups were the 'signature' chronic myelomonocytic leukemia mutations in ASXL1, TET2 and SRSF2. Mutations in CBL were found exclusively in overt chronic myelomonocytic leukemia. In conclusion, we demonstrate clinical and genetic similarities between overt chronic myelomonocytic leukemia and oligomonocytic chronic myelomonocytic leukemia. The findings suggest that at least a subset of oligomonocytic chronic myelomonocytic leukemia represents early phase 'dysplastic type' chronic myelomonocytic leukemia.

Immunophenotypic, cytogenetic, and mutational characterization of cell lines derived from myelodysplastic syndrome patients after progression to acute myeloid leukemia

Leukemia cell lines have been widely used in the hematology field to unravel mechanistic insights and to test new therapeutic strategies. Myelodysplastic syndromes (MDS) comprise a heterogeneous group of diseases that are characterized by ineffective hematopoiesis and frequent progress to acute myeloid leukemia (AML). A few cell lines have been established from MDS patients after progression to AML but their characterization is incomplete. Here we provide a detailed description of the immunophenotypic profile of the MDS-derived cell lines SKK-1, SKM-1, F-36P; and MOLM-13. Specifically, we analyzed a comprehensive panel of markers that are currently applied in the diagnostic routine for myeloid disorders. To provide high-resolution genetic data comprising copy number alterations and losses of heterozygosity we performed whole genome single nucleotide polymorphism-based arrays and included the cell line OHN-GM that harbors the frequent chromosome arm 5q deletion. Furthermore, we assessed the mutational status of 83 disease-relevant genes. Our results provide a resource to the MDS and AML field that allows researchers to choose the best-matching cell line for their functional studies. © 2016 Wiley Periodicals, Inc.