Molecular analysis of myelodysplastic syndrome with isolated deletion of the long arm of chromosome 5 reveals a specific spectrum of molecular mutations with prognostic impact: a study on 123 patients and 27 genes

Subunit-specific analysis of cohesin-mutant myeloid malignancies reveals distinct ontogeny and outcomes

Mutations in the cohesin complex components (STAG2, RAD21, SMC1A, SMC3, and PDS5B) are recurrent genetic drivers in myelodysplastic neoplasm (MDS) and acute myeloid leukemia (AML). Whether the different cohesin subunit mutations share clinical characteristics and prognostic significance is not known. We analyzed 790 cohesin-mutant patients from the Dana-Farber Cancer Institute (DFCI) and the Munich Leukemia Laboratory (MLL), 390 of which had available outcome data, and identified subunit-specific clinical, prognostic, and genetic characteristics suggestive of distinct ontogenies. We found that STAG2 mutations are acquired at MDS stage and are associated with secondary AML, adverse prognosis, and co-occurrence of secondary AML-type mutations. In contrast, mutations in RAD21, SMC1A and SMC3 share features with de novo AML with better prognosis, and co-occurrence with de novo AML-type lesions. The findings show the heterogeneous nature of cohesin complex mutations, and inform clinical and prognostic classification, as well as distinct biology of the cohesin complex.

Myelodysplastic syndromes del(5q): Pathogenesis and its therapeutic implications

Myelodysplastic syndromes (MDS) encompass a heterogeneous set of acquired bone marrow neoplastic disorders characterized by ineffective hematopoiesis within one or more bone marrow lineages. Nearly half of MDS patients carry cytogenetic alterations, with del(5q) being the most prevalent. Since its first description, del(5q) was consistently correlated with a typical clinical phenotype marked by anemia, thrombocytosis, and a low risk of evolving into acute leukemia. Presently, the World Health Organization (WHO) classification of myeloid neoplasms recognizes a specific subtype of MDS known as "myelodysplastic neoplasm with low blast and isolated del(5q)" identified by the sole presence of 5q deletion or in combination with one other abnormality excluding -7/del(7q). Several studies have sought to unravel the biological processes triggered by del(5q) in the development of MDS, revealing the involvement of various genes localized in specific regions of chromosome 5 referred to as common deleted regions (CDR). This intricate biological landscape makes the MDS cells with del(5q) exceptionally sensitive to lenalidomide. Several studies have confirmed the efficacy of lenalidomide in this context. Regrettably, the response to lenalidomide is not conclusive, prompting ongoing research into biological mechanisms that drive patients toward leukemia and strategies to circumvent lenalidomide resistance and disease progression.

Determinants of lenalidomide response with or without erythropoiesis-stimulating agents in myelodysplastic syndromes: the HOVON89 trial

A randomized phase-II study was performed in low/int-1 risk MDS (IPSS) to study efficacy and safety of lenalidomide without (arm A) or with (arm B) ESA/G-CSF. In arm B, patients without erythroid response (HI-E) after 4 cycles received ESA; G-CSF was added if no HI-E was obtained by cycle 9. HI-E served as primary endpoint. Flow cytometry and next-generation sequencing were performed to identify predictors of response. The final evaluation comprised 184 patients; 84% non-del(5q), 16% isolated del(5q); median follow-up: 70.7 months. In arm A and B, 39 and 41% of patients achieved HI-E; median time-to-HI-E: 3.2 months for both arms, median duration of-HI-E: 9.8 months. HI-E was significantly lower in non-del(5q) vs. del(5q): 32% vs. 80%. The same accounted for transfusion independency-at-week 24 (16% vs. 67%), but similar in both arms. Apart from presence of del(5q), high percentages of bone marrow lymphocytes and progenitor B-cells, a low number of mutations, absence of ring sideroblasts, and SF3B1 mutations predicted HI-E. In conclusion, lenalidomide induced HI-E in patients with non-del(5q) and del(5q) MDS without additional effect of ESA/G-CSF. The identified predictors of response may guide application of lenalidomide in lower-risk MDS in the era of precision medicine. (EudraCT 2008-002195-10).

Collaborative effect of Csnk1a1 haploinsufficiency and mutant p53 in Myc induction can promote leukemic transformation

ABSTRACT

It is still not fully understood how genetic haploinsufficiency in del(5q) myelodysplastic syndrome (MDS) contributes to malignant transformation of hematopoietic stem cells. We asked how compound haploinsufficiency for Csnk1a1 and Egr1 in the common deleted region on chromosome 5 affects hematopoietic stem cells. Additionally, Trp53 was disrupted as the most frequently comutated gene in del(5q) MDS using CRISPR/Cas9 editing in hematopoietic progenitors of wild-type (WT), Csnk1a1-/+, Egr1-/+, Csnk1a1/Egr1-/+ mice. A transplantable acute leukemia only developed in the Csnk1a1-/+Trp53-edited recipient. Isolated blasts were indefinitely cultured ex vivo and gave rise to leukemia after transplantation, providing a tool to study disease mechanisms or perform drug screenings. In a small-scale drug screening, the collaborative effect of Csnk1a1 haploinsufficiency and Trp53 sensitized blasts to the CSNK1 inhibitor A51 relative to WT or Csnk1a1 haploinsufficient cells. In vivo, A51 treatment significantly reduced blast counts in Csnk1a1 haploinsufficient/Trp53 acute leukemias and restored hematopoiesis in the bone marrow. Transcriptomics on blasts and their normal counterparts showed that the derived leukemia was driven by MAPK and Myc upregulation downstream of Csnk1a1 haploinsufficiency cooperating with a downregulated p53 axis. A collaborative effect of Csnk1a1 haploinsufficiency and p53 loss on MAPK and Myc upregulation was confirmed on the protein level. Downregulation of Myc protein expression correlated with efficient elimination of blasts in A51 treatment. The "Myc signature" closely resembled the transcriptional profile of patients with del(5q) MDS with TP53 mutation.

Fifth Edition of the World Health Classification of Tumors of the Hematopoietic and Lymphoid Tissue: Myeloid Neoplasms

In this manuscript, we review myeloid neoplasms in the fifth edition of the World Health Organization classification of hematolymphoid tumors (WHO-HEM5), focusing on changes from the revised fourth edition (WHO-HEM4R). Disease types and subtypes have expanded compared with WHO-HEM4R, mainly because of the expansion in genomic knowledge of these diseases. The revised classification is based on a multidisciplinary approach including input from a large body of pathologists, clinicians, and geneticists. The revised classification follows a hierarchical structure allowing usage of family (class)-level definitions where the defining diagnostic criteria are partially met or a complete investigational workup has not been possible. Overall, the WHO-HEM5 revisions to the classification of myeloid neoplasms include major updates and revisions with increased emphasis on genetic and molecular drivers of disease. The most notable changes have been applied to the sections of acute myeloid leukemia and myelodysplastic neoplasms (previously referred to as myelodysplastic syndrome) with incorporation of novel, disease-defining genetic changes. In this review we focus on highlighting the updates in the classification of myeloid neoplasms, providing a comparison with WHO-HEM4R, and offering guidance on how the new classification can be applied to the diagnosis of myeloid neoplasms in routine practice.

Erythroid Differentiation Enhances RNA Mis-Splicing in SF3B1-Mutant Myelodysplastic Syndromes with Ring Sideroblasts

Myelodysplastic syndromes with ring sideroblasts (MDS-RS) commonly develop from hematopoietic stem cells (HSC) bearing mutations in the splicing factor SF3B1 (SF3B1mt). Direct studies into MDS-RS pathobiology have been limited by a lack of model systems that fully recapitulate erythroid biology and RS development and the inability to isolate viable human RS. Here, we combined successful direct RS isolation from patient samples, high-throughput multiomics analysis of cells encompassing the SF3B1mt stem-erythroid continuum, and functional assays to investigate the impact of SF3B1mt on erythropoiesis and RS accumulation. The isolated RS differentiated, egressed into the blood, escaped traditional nonsense-mediated decay (NMD) mechanisms, and leveraged stress-survival pathways that hinder wild-type hematopoiesis through pathogenic GDF15 overexpression. Importantly, RS constituted a contaminant of magnetically enriched CD34+ cells, skewing bulk transcriptomic data. Mis-splicing in SF3B1mt cells was intensified by erythroid differentiation through accelerated RNA splicing and decreased NMD activity, and SF3B1mt led to truncations in several MDS-implicated genes. Finally, RNA mis-splicing induced an uncoupling of RNA and protein expression, leading to critical abnormalities in proapoptotic p53 pathway genes. Overall, this characterization of erythropoiesis in SF3B1mt RS provides a resource for studying MDS-RS and uncovers insights into the unexpectedly active biology of the "dead-end" RS.

SIGNIFICANCE

Ring sideroblast isolation combined with state-of-the-art multiomics identifies survival mechanisms underlying SF3B1-mutant erythropoiesis and establishes an active role for erythroid differentiation and ring sideroblasts themselves in SF3B1-mutant myelodysplastic syndrome pathogenesis.

Significance of SF3B1 Mutations in Myeloid Neoplasms

Myelodysplastic neoplasm with low blasts and SF3B1 mutation (MDS-LB-SF3B1) has undergone significant classification changes in the past year with the publication of the 5th edition of the World Health Organization Classification of Tumors of Haematopoietic and Lymphoid Tissues and the International Consensus Classification. This article reviews the basic biology of SF3B1, iron metabolism, and dysfunction that leads to the formation of ring sideroblasts. It highlights neoplastic and non-neoplastic considerations to the differential diagnoses. Finally, a review on the evolution of the prognostic scoring system and treatment regimens that are available to patients with a diagnosis of MDS is presented.

Genomics of deletion 7 and 7q in myeloid neoplasm: from pathogenic culprits to potential synthetic lethal therapeutic targets

Complete or partial deletions of chromosome 7 (-7/del7q) belong to the most frequent chromosomal abnormalities in myeloid neoplasm (MN) and are associated with a poor prognosis. The disease biology of -7/del7q and the genes responsible for the leukemogenic properties have not been completely elucidated. Chromosomal deletions may create clonal vulnerabilities due to haploinsufficient (HI) genes contained in the deleted regions. Therefore, HI genes are potential targets of synthetic lethal strategies. Through the most comprehensive multimodal analysis of more than 600 -7/del7q MN samples, we elucidated the disease biology and qualified a list of most consistently deleted and HI genes. Among them, 27 potentially synthetic lethal target genes were identified with the following properties: (i) unaffected genes by hemizygous/homozygous LOF mutations; (ii) prenatal lethality in knockout mice; and (iii) vulnerability of leukemia cells by CRISPR and shRNA knockout screens. In -7/del7q cells, we also identified 26 up or down-regulated genes mapping on other chromosomes as downstream pathways or compensation mechanisms. Our findings shed light on the pathogenesis of -7/del7q MNs, while 27 potential synthetic lethal target genes and 26 differential expressed genes allow for a therapeutic window of -7/del7q.

Novel scheme for defining the clinical implications of TP53 mutations in myeloid neoplasia

BACKGROUND

TP53 mutations (TP53MT) occur in diverse genomic configurations. Particularly, biallelic inactivation is associated with poor overall survival in cancer. Lesions affecting only one allele might not be directly leukemogenic, questioning the presence of cryptic biallelic subclones in cases with dismal prognosis.

METHODS

We have collected clinical and molecular data of 7400 patients with myeloid neoplasms and applied a novel model by identifying an optimal VAF cutoff using a statistically robust strategy of sampling-based regression on survival data to accurately classify the TP53 allelic configuration and assess prognosis more precisely.

RESULTS

Overall, TP53MT were found in 1010 patients. Following the traditional criteria, 36% of the cases were classified as single hits, while 64% exhibited double hits genomic configuration. Using a newly developed molecular algorithm, we found that 579 (57%) patients had unequivocally biallelic, 239 (24%) likely contained biallelic, and 192 (19%) had most likely monoallelic TP53MT. Interestingly, our method was able to upstage 192 out of 352 (54.5%) traditionally single hit lesions into a probable biallelic category. Such classification was further substantiated by a survival-based model built after re-categorization. Among cases traditionally considered monoallelic, the overall survival of those with probable monoallelic mutations was similar to the one of wild-type patients and was better than that of patients with a biallelic configuration. As a result, patients with certain biallelic hits, regardless of the disease subtype (AML or MDS), had a similar prognosis. Similar results were observed when the model was applied to an external cohort. In addition, single-cell DNA studies unveiled the biallelic nature of previously considered monoallelic cases.

CONCLUSION

Our novel approach more accurately resolves TP53 genomic configuration and uncovers genetic mosaicism for the use in the clinical setting to improve prognostic evaluation.

Secondary Acute Myeloid Leukemia in Myelodysplastic Syndrome Patients Aged Over 60 Years

In myelodysplastic syndrome (MDS), neoplastic cells originate in hematopoietic stem cells of the bone marrow, causing dysplasia in multiple cell lines. This may ultimately lead to cytopenia and anemia. MDS generally occurs in patients aged over 60 years, and if left unchecked, it can lead to secondary acute myeloid leukemia (AML), which has a worse prognosis than de novo AML. Hence, it is important to find methods to treat and manage MDS and prevent secondary AML. This review tries to point out the best methods to find out the best possible treatment for MDS, which can lead to its remission or possibly cure and prevent it from progressing into AML. In order to do this, the pathogenesis of MDS is taken into account, and it is clear that the various molecular mutations that lead to the hematologic neoplasms directly affect the different chemotherapy agents that can be used. The different common mutations leading to MDS and secondary AML have been reviewed along with the drugs best inclined to target them. Some mutations lead to a worse prognosis than others, and ongoing mutations can lead to drug-resistant neoplasms. Thus, drugs targeting the mutations need to be used. The feasibility of an allogeneic stem cell transplant is also taken into account, as this can lead to a total cure of MDS. Methods of decreasing post-transplant recovery time and complications have been looked into, and more studies need to be done on the matter. Currently, it is clear that a more personalized approach to each individual case with its own set of drug combinations is the best approach to treating MDS and secondary leukemia and increasing the overall survival (OS).

Molecular patterns identify distinct subclasses of myeloid neoplasia

Genomic mutations drive the pathogenesis of myelodysplastic syndromes and acute myeloid leukemia. While morphological and clinical features have dominated the classical criteria for diagnosis and classification, incorporation of molecular data can illuminate functional pathobiology. Here we show that unsupervised machine learning can identify functional objective molecular clusters, irrespective of anamnestic clinico-morphological features, despite the complexity of the molecular alterations in myeloid neoplasia. Our approach reflects disease evolution, informed classification, prognostication, and molecular interactions. We apply machine learning methods on 3588 patients with myelodysplastic syndromes and secondary acute myeloid leukemia to identify 14 molecularly distinct clusters. Remarkably, our model shows clinical implications in terms of overall survival and response to treatment even after adjusting to the molecular international prognostic scoring system (IPSS-M). In addition, the model is validated on an external cohort of 412 patients. Our subclassification model is available via a web-based open-access resource ( https://drmz.shinyapps.io/mds_latent ).

The Genetic Landscape of Myelodysplastic Neoplasm Progression to Acute Myeloid Leukemia

Myelodysplastic neoplasm (MDS) represents a heterogeneous group of myeloid disorders that originate from the hematopoietic stem and progenitor cells that lead to the development of clonal hematopoiesis. MDS was characterized by an increased risk of transformation into acute myeloid leukemia (AML). In recent years, with the aid of next-generation sequencing (NGS), an increasing number of molecular aberrations were discovered, such as recurrent mutations in FLT3, NPM1, DNMT3A, TP53, NRAS, and RUNX1 genes. During MDS progression to leukemia, the order of gene mutation acquisition is not random and is important when considering the prognostic impact. Moreover, the co-occurrence of certain gene mutations is not random; some of the combinations of gene mutations seem to have a high frequency (ASXL1 and U2AF1), while the co-occurrence of mutations in splicing factor genes is rarely observed. Recent progress in the understanding of molecular events has led to MDS transformation into AML and unraveling the genetic signature has paved the way for developing novel targeted and personalized treatments. This article reviews the genetic abnormalities that increase the risk of MDS transformation to AML, and the impact of genetic changes on evolution. Selected therapies for MDS and MDS progression to AML are also discussed.

Novel Scheme for Defining the Clinical Implications of TP53 Mutations in Myeloid Neoplasia

Background: TP53 mutations ( TP53 MT ) occur in diverse genomic configurations. Particularly, biallelic inactivation is associated with poor overall survival in cancer. Lesions affecting only one allele might not be directly leukemogenic, questioning the presence of cryptic biallelic subclones in cases with dismal prognosis. Methods: We have collected clinical and molecular data of 7400 patients with myeloid neoplasms and applied a novel model to properly resolve the allelic configuration of TP53 MT and assess prognosis more precisely. Results: Overall, TP53 MT were found in 1010 patients. Following the traditional criteria, 36% of cases were classified as single hits while 64% exhibited double hits genomic configuration. Using a newly developed molecular algorithm, we found that 579 (57%) patients had unequivocally biallelic, 239 (24%) likely contained biallelic, and 192 (19%) had most likely monoallelic TP53 MT . Such classification was further substantiated by a survival-based model built after re-categorization. Among cases traditionally considered monoallelic, the overall survival of those with probable monoallelic mutations was similar to the one of wild-type patients and was better than that of patients with a biallelic configuration. As a result, patients with certain biallelic hits, regardless of the disease subtype (AML or MDS), had a similar prognosis. Similar results were observed when the model was applied to an external cohort. These results were recapitulated by single-cell DNA studies, which unveiled the biallelic nature of previously considered monoallelic cases. Conclusion: Our novel approach more accurately resolves TP53 genomic configuration and uncovers genetic mosaicism for the use in the clinical setting to improve prognostic evaluation.

SF3B1 mutated MDS: Blast count, genetic co-abnormalities and their impact on classification and prognosis

Recently, MDS with mutated SF3B1 and blast count <5% was proposed as distinct entity with favorable prognosis by the international working group for the prognosis of MDS (IWG-PM), the 5th edition of the WHO classification and the International Consensus Classification. To further characterize this entity with respect to the genomic landscape, AML transformation rate and clinical outcome, we analyzed 734 MDS patients by whole genome sequencing. SF3B1 mutations were identified in 31% (n = 231), most frequently accompanied by TET2 mutations (29%). 144/231 (62%) SF3B1mut samples fulfilled entity criteria proposed by IWG-PM (SF3B1ent). These cases were associated with longer survival, lower AML transformation rate, normal karyotypes and harbored less accompanying mutations compared to SF3B1mut samples not falling into the proposed SF3B1 entity (SF3B1nent). Of SF3B1mut cases 7% (15/231; SF3B1ent: 3/144 [2%]; SF3B1nent: 12/87 [14%]) progressed to AML compared to 15% SF3B1 wild-type patients (75/503). Of these 15 SF3B1mut cases, 10 (67%) showed RUNX1 mutations at MDS or AML stage. Multivariate analysis revealed that del(5q) and RUNX1 mutations were independent negative prognostic factors for overall survival, while blast count >5% was not. In conclusion, SF3B1mut MDS has a favorable prognosis independent of blast count if karyotype and RUNX1 mutations are considered.

Myelodysplastic Syndromes with Isolated del(5q): Value of Molecular Alterations for Diagnostic and Prognostic Assessment

Myelodysplastic syndromes (MDS) are a group of clonal hematological neoplasms characterized by ineffective hematopoiesis in one or more bone marrow cell lineages. Consequently, patients present with variable degrees of cytopenia and dysplasia. These characteristics constitute the basis for the World Health Organization (WHO) classification criteria of MDS, among other parameters, for the current prognostic scoring system. Although nearly half of newly diagnosed patients present a cytogenetic alteration, and almost 90% of them harbor at least one somatic mutation, MDS with isolated del(5q) constitutes the only subtype clearly defined by a cytogenetic alteration. The results of several clinical studies and the advances of new technologies have allowed a better understanding of the biological basis of this disease. Therefore, since the first report of the "5q- syndrome" in 1974, changes and refinements have been made in the definition and the characteristics of the patients with MDS and del(5q). Moreover, specific genetic alterations have been found to be associated with the prognosis and response to treatments. The aim of this review is to summarize the current knowledge of the molecular background of MDS with isolated del(5q), focusing on the clinical and prognostic relevance of cytogenetic alterations and somatic mutations.

Prognostication in myelodysplastic syndromes (neoplasms): Molecular risk stratification finally coming of age

Accurate risk prognostication is central to the management of myelodysplastic syndromes, given the widely heterogeneous clinical outcomes of these bone marrow failure disorders. Over the past decade, the rapidly expanding compendium of molecular lesions in myelodysplastic syndrome (MDS) has offered unprecedented insight into MDS pathobiology. Recently, molecular prognostic models such as the Molecular International Prognostic Scoring System (IPSS-M) have leveraged the wellspring of genetic data to improve upon traditional risk models such as the Revised IPSS (IPSS-R), but also added substantial complexity. In this review, we highlight early MDS prognostic models, the significant advancements in MDS genomics since then, and the recent advent of molecular based prognostic models. We conclude by discussing important opportunities and challenges in the management of MDS as we arrive at the molecular frontier.

Therapeutic Outcomes and Prognostic Impact of Gene Mutations Including TP53 and SF3B1 in Patients with Del(5q) Myelodysplastic Syndromes (MDS)

BACKGROUND

Genetic alterations are increasingly being recognized to play an important role in both diagnosis and prognosis of MDS. In general, MDS patients with SF3B1 mutations (MT) are known to have favorable outcomes whereas those with TP53 mutations have dismal survivals. However, it is unclear if the impact of these mutations applies to all subtypes of MDS including del(5q) which is known for its response to lenalidomide and better prognosis.

MATERIALS AND METHODS

We retrospectively reviewed 132 del(5q) MDS patients who were treated at the Moffitt Cancer Center (2001-2019).

RESULTS

Among patients who received lenalidomide (n = 98), 50%, 42.9%, and 7.1% achieved hematologic improvement or better, no response, and disease progression/death with a median overall survival (mOS) of 93.2, 72.4, and 25.6 months, respectively (P < .0001). The mOS was 73.3 months but only 25.6 months after patients stopped lenalidomide. TP53 was the most common mutation accounting for 23.8% of the patients. Of the 63 patients with molecular data available, 23.8% harbored TP53 MT and 10% with SF3B1 MT. TP53 status did not impact OS (MT 86.4 vs. wild-type (WT) 73.3 months; P = .72) but those with SF3B1 mutations had a significantly shorter mOS compared to WT (23.9 vs. 83.5 months; P = .001). Multivariate analysis confirmed lenalidomide response and SF3B1 mutations are independently associated with outcomes.

CONCLUSION

Our findings indicate many del(5q) MDS patients will benefit from lenalidomide but survival after its failure is limited. Mutations known to have prognostic impact in MDS at large may not have the same implications in the del(5q) subset.

Towards Understanding the Pathogenicity of DROSHA Mutations in Oncohematology

Myelodysplastic syndrome (MDS) refers to a heterogeneous group of closely related clonal hematopoietic disorders, which are characterized by accumulation of somatic mutations. The acquired mutation burden is suggested to define the pathway and consequent phenotype of the pathology. Recent studies have called attention to the role of miRNA biogenesis genes in MDS progression; in particular, the mutational pressure of the DROSHA gene was determined. Therefore, this highlights the importance of studying the impact of all collected missense mutations found within the DROSHA gene in oncohematology that might affect the functionality of the protein. In this study, the selected mutations were extensively examined by computational screening, and the most deleterious were subjected to a further molecular dynamic simulation in order to uncover the molecular mechanism of the structural damage to the protein altering its biological function. The most significant effect was found for variants I625K, L1047S, and H1170D, presumably affecting the endonuclease activity of DROSHA. Such alterations arisen during MDS progression should be taken into consideration as evoking certain clinical traits in the malignifying clonal evolution.

Evaluating the Effect of 3'-UTR Variants in DICER1 and DROSHA on Their Tissue-Specific Expression by miRNA Target Prediction

Untranslated gene regions (UTRs) play an important role in controlling gene expression. 3'-UTRs are primarily targeted by microRNA (miRNA) molecules that form complex gene regulatory networks. Cancer genomes are replete with non-coding mutations, many of which are connected to changes in tumor gene expression that accompany the development of cancer and are associated with resistance to therapy. Therefore, variants that occurred in 3'-UTR under cancer progression should be analysed to predict their phenotypic effect on gene expression, e.g., by evaluating their impact on miRNA target sites. Here, we analyze 3'-UTR variants in DICER1 and DROSHA genes in the context of myelodysplastic syndrome (MDS) development. The key features of this analysis include an assessment of both "canonical" and "non-canonical" types of mRNA-miRNA binding and tissue-specific profiling of miRNA interactions with wild-type and mutated genes. As a result, we obtained a list of DICER1 and DROSHA variants likely altering the miRNA sites and, therefore, potentially leading to the observed tissue-specific gene downregulation. All identified variants have low population frequency consistent with their potential association with pathology progression.

Machine Learning Integrates Genomic Signatures for Subclassification Beyond Primary and Secondary Acute Myeloid Leukemia

While genomic alterations drive the pathogenesis of acute myeloid leukemia (AML), traditional classifications are largely based on morphology and prototypic genetic founder lesions define only a small proportion of AML patients. The historical subdivision of primary/de novo AML (pAML) and secondary AML (sAML) has shown to variably correlate with genetic patterns. Perhaps, the combinatorial complexity and heterogeneity of AML genomic architecture have precluded, so far, the genomic-based subclassification to identify distinct molecularly-defined subtypes more reflective of shared pathogenesis. We integrated cytogenetic and gene sequencing data from a multicenter cohort of 6,788 AML patients that were analyzed using standard and machine learning methods to generate a novel AML molecular subclassification with biological correlates corresponding to underlying pathogenesis. Standard supervised analyses resulted in modest cross-validation accuracy when attempting to use molecular patterns to predict traditional pathomorphological AML classifications. We performed unsupervised analysis by applying Bayesian Latent Class method that identified 4 unique genomic clusters of distinct prognoses. Invariant genomic features driving each cluster were extracted and resulted in 97% cross-validation accuracy when used for genomic subclassification. Subclasses of AML defined by molecular signatures overlapped current pathomorphological and clinically-defined AML subtypes. We internally and externally validated our results and share an open-access molecular classification scheme for AML patients. Although the heterogeneity inherent in the genomic changes across nearly 7,000 AML patients is too vast for traditional prediction methods, however, machine learning methods allowed for the definition of novel genomic AML subclasses indicating that traditional pathomorphological definitions may be less reflective of overlapping pathogenesis.

Prognosis in Myelodysplastic Syndromes: The Clinical Challenge of Genomic Integration

Myelodysplastic syndromes (MDS) are a group of clonal hematopoietic neoplasms characterized by ineffective hematopoiesis and myelodysplasia with a variable spectrum of clinical-biological features that can be used to build a prognostic estimation. This review summarizes the current most widely used prognostic scoring systems and gives a general view of the prognostic impact of somatic mutations in MDS patients.

Myelodysplastic syndromes and overlap syndromes

Myelodysplastic syndromes (MDS) are a heterogeneous group of clonal hematological neoplasms characterized by ineffective hematopoiesis, morphologic dysplasia, and cytopenia. MDS overlap syndromes include various disorders, such as myelodysplastic/myeloproliferative neoplasms and hypoplastic MDS with aplastic anemia characteristics. MDS overlap syndromes share the characteristics of other diseases, which make differential diagnoses challenging. Advances in genomic studies have led to the discovery of frequent mutations in MDS and overlap syndromes; however, most of the mutations are not specific for the diagnosis of these diseases. The molecular characteristics of the overlap syndromes usually do not show a just "in-between" form but rather heterogeneous features. Established diagnostic criteria for these diseases based on clinical, morphologic, and laboratory features are still useful when combined with genomic data. It is expected that further studies for MDS and overlap syndromes will place emphasis on the roles of mutations as therapeutic targets and prognostic indicators.

High mutation burden in the checkpoint and micro-RNA processing genes in myelodysplastic syndrome

A number of sequencing studies identified the prognostic impact of somatic mutations in myelodysplastic syndrome (MDS). However the majority of them focused on methylation regulation, apoptosis and proliferation genes. Despite the number of experimental studies published on the role of micro-RNA processing and checkpoint genes in the development of MDS, the clinical data about mutational landscape in these genes is limited. We performed a pilot study which evaluated mutational burden in these genes and their association with common MDS mutations. High prevalence of mutations was observed in the genes studied: 54% had mutations in DICER1, 46% had mutations in LAG3, 20% in CTLA4, 23% in B7-H3, 17% in DROSHA, 14% in PD-1 and 3% in PD-1L. Cluster analysis that included these mutations along with mutations in ASXL1, DNMT3A, EZH2, IDH1, RUNX1, SF3B1, SRSF2, TET2 and TP53 effectively predicted overall survival in the study group (HR 4.2, 95%CI 1.3-13.6, p = 0.016). The study results create the rational for incorporating micro-RNA processing and checkpoint genes in the sequencing panels for MDS and evaluate their role in the multicenter studies.

Traipsing Through Muddy Waters: A Critical Review of the Myelodysplastic Syndrome/Myeloproliferative Neoplasm (MDS/MPN) Overlap Syndromes

Myelodysplastic syndrome/Myeloproliferative neoplasms (MDS/MPNs) are molecularly complex, clinically heterogeneous diseases that exhibit proliferative and dysplastic features. Diagnostic criteria use clinical, pathologic, and genomic features to distinguish between disease entities, though considerable clinical and genetic overlap persists. MDS/MPNs are associated with a poor prognosis, save for MDS/MPN with ring sideroblasts and thrombocytosis, which can behave more indolently. The current treatment approach is risk-adapted and symptom-directed and largely extrapolated from experience in MDS or MPN. Gene sequencing has demonstrated frequent mutations involving signaling, epigenetic, and splicing pathways, which present numerous therapeutic opportunities for clinical investigation.

TET-dioxygenase deficiency in oncogenesis and its targeting for tumor-selective therapeutics

TET2 is one of the most frequently mutated genes in myeloid neoplasms. TET2 loss-of-function perturbs myeloid differentiation and causes clonal expansion. Despite extensive knowledge regarding biochemical mechanisms underlying distorted myeloid differentiation, targeted therapies are lagging. Here we review known biochemical mechanisms and candidate therapies that emerge from this. Specifically, we discuss the potential utility of vitamin C to compensate for TET-dioxygenase deficiency, to thereby restore the biochemical function. An alternative approach exploits the TET-deficient state for synthetic lethality, exploiting the fact that a minimum level of TET-dioxygenase activity is required for cell survival, rendering TET2-mutant malignant cells selectively vulnerable to inhibitors of TET-function.

Myelodysplastic syndromes: a review of therapeutic progress over the past 10 years

INTRODUCTION

Myelodysplastic syndromes (MDS) represent a range of bone marrow disorders, with patients affected by cytopenias and risk of progression to AML. There are limited therapeutic options available for patients, including hypomethylating agents (azacitidine/decitabine), growth factor support, lenalidomide, and allogeneic stem cell transplant.

AREAS COVERED

This review provides an overview of the progress made over the past decade for emerging therapies for lower- and higher-risk MDS (MDS-HR). We also cover advances in prognostication, supportive care, and use of allogeneic SCT in MDS.

EXPERT OPINION

While there have been no FDA-approved therapies for MDS in the past decade, we anticipate the approval of luspatercept based on results from the MEDALIST trial for patients with lower-risk MDS (MDS-LR) and ringed sideroblasts who have failed or are ineligible for erythropoiesis stimulating agents (ESAs). With growing knowledge of the biologic and molecular mechanisms underlying MDS, it is anticipated that new therapies will be approved in the coming years.

TP53 in Myelodysplastic Syndromes: Recent Biological and Clinical Findings

TP53 dysregulation plays a pivotal role in the molecular pathogenesis of myelodysplastic syndromes (MDS), identifying a subgroup of patients with peculiar features. In this review we report the recent biological and clinical findings of TP53-mutated MDS, focusing on the molecular pathways activation and on its impact on the cellular physiology. In MDS, TP53 mutational status is deeply associated with del(5q) syndrome and its dysregulation impacts on cell cycle, DNA repair and apoptosis inducing chromosomal instability and the clonal evolution of disease. TP53 defects influence adversely the MDS clinical outcome and the treatment response rate, thus new therapeutic approaches are being developed for these patients. TP53 allelic state characterization and the mutational burden evaluation can therefore predict prognosis and identify the subgroup of patients eligible for targeted therapy. For these reasons, in the era of precision medicine, the MDS diagnostic workup cannot do without the complete assessment of TP53 mutational profile.

Myeloid neoplasm with isolated del(5q) and the MPLW515L mutation fulfills the WHO diagnostic criteria for ET

A 70-year-old male was referred to our hospital for marked thrombocytosis without anemia. The patient simultaneously presented with an MPL W515L mutation, one of the major driver mutations in essential thrombocythemia (ET), and deletion of 5q, a characteristic cytogenetic abnormality in myelodysplastic syndrome (MDS). Bone marrow examination showed a combination of both mature hyperlobulated megakaryocytes, as found in ET, and small hypolobulated megakaryocytes, typically found in MDS with del(5q). The present case is consistent with the recently proposed category of myeloid neoplasms with isolated del(5q) and an MPN driver mutation.

Myelodysplastic/myeloproliferative neoplasms: are morphology and immunophenotyping still relevant?

The term myelodysplastic/myeloproliferative neoplasm (MDS/MPN) refers to a group of clonal hematopoietic neoplasms with overlapping clinical, morphologic and genetic myelodysplastic and myeloproliferative features observed at the time of first presentation. Impaired hematopoiesis morphologically associated with evidence of myelodysplasia manifests clinically with cytopenia/s. Simultaneously, myeloproliferation is seen within the bone marrow and leads to cytosis in the peripheral blood. The diagnostic category of MDS/MPN encompasses a heterogeneous group of diseases which share similarities among them, but at the same time have distinct clinical and pathologic features and eventually diverse prognosis; such differences justify their separation in a classification scheme. In the era of genetic and genomic tests, their distinction from conventional myelodysplastic syndromes or myeloproliferative neoplasms still relies on close clinocopathological correlation, with evaluation of both peripheral blood and bone marrow samples being essential in this sense. A multiparametric integration of clinicopathologic data and cytogenetics and molecular genetics results is the preferred diagnostic approach.

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.

How we manage adults with myelodysplastic syndrome

The prognosis in Myelodysplastic syndromes (MDS), although recently refined by molecular studies, remains largely based on conventional prognostic scores [International Prognostic Scoring System (IPSS), revised IPSS], classifying patients into "lower risk" MDS (LR-MDS) and "higher risk" MDS (HR-MDS). In LR-MDS, treatment mainly aims at improving cytopenias, principally anaemia, while in HR-MDS it aims at delaying disease progression and prolonging survival. In LR-MDS without deletion 5q, anaemia is generally treated first by erythropoietic stimulating factors, while second line treatments are currently not approved [lenalidomide, hypomethylating agents (HMA), luspatercept] or rarely indicated (antithymocyte globulin). Lenalidomide has major efficacy in LR-MDS with deletion 5q. Allogeneic stem cell transplantation (allo-SCT) is sometimes considered in LR-MDS, and iron chelation can be considered when multiple red blood cell transfusions are required. Allo-SCT is the only potentially curative treatment for HR-MDS; however, it is rarely applicable. It is generally preceded by intensive chemotherapy (IC) or HMA in patients with excess of marrow blasts (especially if >10%). In other patients, HMA can improve survival. The role of new drugs, including venetoclax or, in case of specific mutations, IDH1 or IDH2 inhibitors, is investigated. IC is mainly indicated as a bridge to allo-SCT, in the absence of unfavourable karyotype.

Clinical and Prognostic Significance of Cell Sensitivity to Chemotherapy Detected in vitro on Treatment Response and Survival of Leukemia Patients

Multidrug resistance (MDR) is a major challenge in leukemia treatment. The objective of this study was to identity predictors of MDR to allow for rapid and economical assessment of the efficacy of planned antitumor therapy for leukemia patients. The study included 113 patients with acute and chronic leukemias. Prior to antitumor therapy, we measured the sensitivity of tumor cells of patients to the panel of chemotherapeutic drugs, together with MDR1 mRNA and P-glycoprotein (P-gp) expression as one of the mechanisms of MDR, and compared these data with the response to therapy. The scales for leukemia patients according to therapy response, drug sensitivity of tumor cells, MDR1 mRNA and P-gp levels, and the presence of unfavorable immunological and cytogenetic markers were introduced for subsequent correlation analysis. We show that the drug resistance of tumor cells of leukemia patients estimated in vitro at diagnosis correlates with a poor response to chemotherapy and is usually combined with aberrant and immature immunological markers, cytogenetic abnormalities, and a high expression of MDR1 mRNA and P-gp. All together, these factors indicate unfavorable prognosis and low survival of leukemia patients. Thus, the sensitivity of tumor cells to chemotherapeutic drugs measured in vitro at diagnosis may have prognostic value for individual types of leukemia.

Effect of RNA splicing machinery gene mutations on prognosis of patients with MDS: A meta-analysis

BACKGROUND

Gene mutations with important prognostic role have been identified in patients with myelodysplastic syndrome (MDS). We performed a meta-analysis to investigate the effects of RNA splicing machinery gene mutations on prognosis of MDS patients.

METHODS

We searched English database including PubMed, Embase, Cochrane Library for literatures published within recent 10 years on the effect of RNA splicing machinery genes in MDS. Revman version 5.2 software was used for all the statistical processing. We calculated risk ratio and 95% confidence interval (CI) of continuous variables, and find hazard ratio (HR) and 95% CI of time-to-event data.

RESULTS

We included 19 studies enrolling 4320 patients. There is a significant superior overall survival (OS) in splicing factor 3b, subunit 1 (SF3B1)-mutation group compared to unmutated group (HR = 0.58, 95% CI: 0.5-0.67, P < .00001); OS decreased significantly in serine/arginine-rich splicing factor 2/ U2 auxiliary factor protein 1 (SRSF2/U2AF1) mutation group compared to unmutated group, (HR = 1.62, 95% CI: 1.34-1.97, P < .00001 and HR = 1.61, 95% CI: 1.35-1.9, P < .00001, respectively). In terms of leukemia-free survival (LFS), the group with SF3B1 mutation had better outcome than unmutated group, HR = 0.63 (95% CI: 0.53-0.75, P < .00001). Other RNA splicing gene mutation group showed significant poor LFS than unmutated groups, (HR = 1.89, 95% CI: 1.6-2.23, P < .00001; HR = 2.77, 95% CI: 2.24-3.44, P < .00001; HR = 1.48, 95% CI: 1.08-2.03, P < .00001; for SRSF2, U2AF1, and zinc finger CCCH-type, RNA binding motif and serine/arginine rich 2 [ZRSR2], respectively). As for subgroup of low- or intermediate-1-IPSS risk MDS, SRSF2, and U2AF1 mutations were related to poor OS. (HR = 1.83, 95% CI: 1.43-2.35, P < .00001; HR = 2.11, 95% CI: 1.59-2.79, P < .00001 for SRSF2 and U2AF1, respectively). SRSF2 and U2AF1 mutations were strongly associated with male patients. SF3B1 mutation was strongly associated with disease staging.

CONCLUSION

This meta-analysis indicates a positive effect of SF3B1 and an adverse prognostic effect of SRSF2, U2AF1, and ZRSR2 mutations in patients with MDS. Mutations of RNA splicing genes have important effects on the prognosis of MDS.

Society of Hematologic Oncology (SOHO) State of the Art Updates and Next Questions: Myelodysplastic Syndromes

In the past few months, 2 main streams of research have dominated the panorama of myelodysplastic syndrome (MDS) investigations: deepening the insight into the pathogenic role, hierarchy, and prognostic effect of somatic mutations and, as a consequence, into the effect of inherited congenital predisposing conditions and the second, quite interlinked with the first, analyzing inflammation and innate immunity in patients with MDS. The research devoted to clarifying the mechanisms of action and mechanisms of resistance to hypomethylating agents has also advanced, mostly resulting from different approaches to the study of DNA methylation. Recent observations have reinforced support for targeted therapies for selected subgroups of MDS patients.

The Molecular Pathology of Myelodysplastic Syndrome

The diagnosis and classification of myelodysplastic syndromes (MDS) are based on cytomorphology and cytogenetics (WHO classification). Prognosis is best defined by the Revised International Prognostic Scoring System (IPSS-R). In recent years, an increasing number of molecular aberrations have been discovered. They are already included in the classification (e.g., SF3B1) and, more importantly, have emerged as valuable markers for better classification, particularly for defining risk groups. Mutations in genes such as SF3B1 and IDH1/2 have already had an impact on targeted treatment approaches in MDS.