SF3B1 mutation identifies a distinct subset of myelodysplastic syndrome with ring sideroblasts

Altered RNA export by SF3B1 mutants confers sensitivity to nuclear export inhibition

SF3B1 mutations frequently occur in cancer yet lack targeted therapies. Clinical trials of XPO1 inhibitors, selinexor and eltanexor, in high-risk myelodysplastic neoplasms (MDS) revealed responders were enriched with SF3B1 mutations. Given that XPO1 (Exportin-1) is a nuclear exporter responsible for the export of proteins and multiple RNA species, this led to the hypothesis that SF3B1-mutant cells are sensitive to XPO1 inhibition, potentially due to altered splicing. Subsequent RNA sequencing after XPO1 inhibition in SF3B1 wildtype and mutant cells showed increased nuclear retention of RNA transcripts and increased alternative splicing in the SF3B1 mutant cells particularly of genes that impact apoptotic pathways. To identify novel drug combinations that synergize with XPO1 inhibition, a forward genetic screen was performed with eltanexor treatment implicating anti-apoptotic targets BCL2 and BCLXL, which were validated by functional testing in vitro and in vivo. These targets were tested in vivo using Sf3b1K700E conditional knock-in mice, which showed that the combination of eltanexor and venetoclax (BCL2 inhibitor) had a preferential sensitivity for SF3B1 mutant cells without excessive toxicity. In this study, we unveil the mechanisms underlying sensitization to XPO1 inhibition in SF3B1-mutant MDS and preclinically rationalize the combination of eltanexor and venetoclax for high-risk MDS.

Clinical Outcomes and Healthcare Resource Utilization for Patients With Lower-Risk Myelodysplastic Syndromes Treated With Erythropoiesis-Stimulating Agents

INTRODUCTION

Real-world studies of lower-risk myelodysplastic syndromes (LR-MDS) are limited. We evaluated treatment patterns, clinical outcomes, and healthcare resource utilization (HCRU) among patients with LR-MDS treated with erythropoiesis-stimulating agents (ESAs) in the United States.

PATIENTS AND METHODS

This retrospective study included patients with LR-MDS who initiated treatment with ESAs between January 1, 2016 and June 30, 2019. The primary analysis assessed patient demographic and clinical characteristics, treatment patterns, clinical outcomes (hematologic response, transfusion requirements, disease progression), and HCRU (medical encounters, laboratory tests, and medication use). Subgroup analyses of patients repeatedly treated with ESA therapy evaluated selected clinical outcomes and primary ESA failure by SF3B1 mutational status, per recently updated NCCN Clinical Practice Guidelines in Oncology (NCCN Guidelines©).

RESULTS

A total of 142 patients were included with a median follow-up time of 17 months (interquartile range [IQR], 7-33). Median age at ESA initiation was 79 years (IQR, 73-85). Patients were predominantly male (54%), overweight or obese (32% and 23%, respectively), of White race (96%) and non-Hispanic ethnicity (89%). Overall, 57% patients were initially treated with darbepoetin alfa and 43% with epoetin alfa. Clinical outcomes were poor, and there was a significant burden on both the health system and individual patients treated with ESA therapies. Hematologic improvement- erythroid was only seen in 26% of 142 patients treated with ESAs, and 65% of 82 retreated patients experienced primary ESA failure.

CONCLUSION

Our results indicate that primary ESA failure is largely unrecognized and that many patients should be considered for alternative treatments.

Incorporation mutational profile might reduce the importance of blast count in prognostication of low-risk myelodysplastic syndromes

Addition of molecular data to prognostic models has improved risk stratification of myelodysplastic neoplasms (MDS). However, the role of molecular lesions, particularly in the group of low-risk disease (LR-MDS), is uncertain. We evaluated a set of 227 patients with LR-MDS. Overall survival (OS) and probability of leukaemic progression were the main endpoints. RUNX1 was associated with lower OS and SF3B1 with a reduced risk of death (HR: 1.7, 95% CI, 1.1-2.9; p = 0.05; and HR: 0.23, 95% CI 0.1-0.5; p < 0.001; respectively). TP53 and RUNX1 mutations were predictive covariates for the probability of leukaemic progression (p < 0.001). Blast percentage, neither analysed as categorical (<5% vs. 5%-9%; HR: 1.3, 95% CI, 0.7-2.9; p = 0.2) nor as a continuous variable (HR: 1.07, 95% CI, 0.9-1.1; p = 0.07), had impact on survival or probability of progression (sHR: 1.05, 95% CI, 0.9-1.1; p = 0.2). These results retained statistical significance when analysis was restricted to the definition of LR-MDS according to the WHO 2022 and ICC classifications (<5% blasts). Thus, with the incorporation of molecular data, blast percentage happens to lose clinical significance both for survival and probability of progression in the group of patients with LR-MDS.

Chronic myelomonocytic leukemia with ring sideroblasts/SF3B1 mutation presents with low monocyte count and resembles myelodysplastic syndromes with-RS/SF3B1 mutation in terms of phenotype and prognosis

Introduction

Chronic myelomonocytic leukemia (CMML) and myelodysplastic syndromes (MDS) with ring sideroblasts (RS) or SF3B1 mutation (MDS-RS/SF3B1) differ in many clinical features, but share others, such as anemia. RS and SF3B1 mutation can also be found in CMML.

Methods

We compared CMML with and without RS/SF3B1 and MDS-RS/SF3B1 considering the criteria established by the 2022 World Health Organization classification.

Results

A total of 815 patients were included (CMML, n=319, CMML-RS/SF3B1, n=172 and MDS-RS/SF3B1, n=324). The percentage of RS was ≥15% in almost all CMML-RS/SF3B1 patients (169, 98.3%) and most (125, 72.7%) showed peripheral blood monocyte counts between 0.5 and 0.9 x109/L and low risk prognostic categories. CMML-RS/SF3B1 differed significantly from classical CMML in the main clinical characteristics, whereas it resembled MDS-RS/SF3B1. At a molecular level, CMML and CMML-RS/SF3B1 had a significantly higher frequency of mutations in TET2 (mostly multi-hit) and ASXL1 (p=0.013) and CMML had a significantly lower frequency of DNMT3A and SF3B1 mutations compared to CMML/MDS-RS/SF3B1. Differences in the median overall survival among the three groups were statistically significant: 6.75 years (95% confidence interval [CI] 5.41-8.09) for CMML-RS/SF3B1 vs. 3.17 years (95% CI 2.56-3.79) for CMML vs. 16.47 years (NA) for MDS-RS/SF3B1, p<0.001. Regarding patients with CMML and MDS, both with SF3B1 mutation, survival did not significantly differ. CMML had a higher risk of transformation to acute myeloid leukemia (24% at 8 years, 95%CI 19%-30%).

Discussion

CMML-RS/SF3B1 mutation resembles MDS-RS/SF3B1 in terms of phenotype and clearly differs from CMML. The presence of ≥15% RS and/or SF3B1 in CMML is associated with a low monocyte count. SF3B1 mutation clearly improves the prognosis of CMML.

Predicting survival in patients with myelodysplastic/myeloproliferative neoplasms with SF3B1 mutation and thrombocytosis

We investigated data from 180 consecutive patients with myelodysplastic/myeloproliferative neoplasms with SF3B1 mutation and thrombocytosis (MDS/MPN-SF3B1-T) who were diagnosed according to the 2022 World Health Organization (WHO) classification of myeloid neoplasms to identify covariates associated with survival. At a median follow-up of 48 months (95% confidence interval [CI] 35-61 months), the median survival was 69 months (95% CI 59-79 months). Patients with bone marrow ring sideroblasts (RS) < 15% had shorter median overall survival (OS) than did those with bone marrow RS ≥ 15% (41 months [95% CI 32-50 months] versus 76 months [95% CI 59-93 months]; P < 0.001). According to the univariable analyses of OS, age ≥ 65 years (P < 0.001), hemoglobin concentration (Hb) < 80 g/L (P = 0.090), platelet count (PLT) ≥ 800 × 10E + 9/L (P = 0.087), bone marrow RS < 15% (P < 0.001), the Revised International Prognostic Scoring System (IPSS-R) cytogenetic category intermediate/poor/very poor (P = 0.005), SETBP1 mutation (P = 0.061) and SRSF2 mutation (P < 0.001) were associated with poor survival. Based on variables selected from univariable analyses, two separate survival prediction models, a clinical survival model, and a clinical-molecular survival model, were developed using multivariable analyses with the minimum value of the Akaike information criterion (AIC) to specifically predict outcomes in patients with MDS/MPN-SF3B1-T according to the 2022 WHO classification.

Understanding iron homeostasis in MDS: the role of erythroferrone

Myelodysplastic neoplasms (MDS) are a heterogenous group of clonal stem cell disorders characterized by dysplasia and cytopenia in one or more cell lineages. Anemia is a very common symptom that is often treated with blood transfusions and/or erythropoiesis stimulating factors. Iron overload results from a combination of these factors together with the disease-associated ineffective erythropoiesis, that is seen especially in MDS cases with SF3B1 mutations. A growing body of research has shown that erythroferrone is an important regulator of hepcidin, the master regulator of systemic iron homeostasis. Consequently, it is of interest to understand how this molecule contributes to regulating the iron balance in MDS patients. This short review evaluates our current understanding of erythroferrone in general, but more specifically in MDS and seeks to place in context how the current knowledge could be utilized for prognostication and therapy.

Biological relevance of alternative splicing in hematologic malignancies

Alternative splicing (AS) is a strictly regulated process that generates multiple mRNA variants from a single gene, thus contributing to proteome diversity. Transcriptome-wide sequencing studies revealed networks of functionally coordinated splicing events, which produce isoforms with distinct or even opposing functions. To date, several mechanisms of AS are deregulated in leukemic cells, mainly due to mutations in splicing and/or epigenetic regulators and altered expression of splicing factors (SFs). In this review, we discuss aberrant splicing events induced by mutations affecting SFs (SF3B1, U2AF1, SRSR2, and ZRSR2), spliceosome components (PRPF8, LUC7L2, DDX41, and HNRNPH1), and epigenetic modulators (IDH1 and IDH2). Finally, we provide an extensive overview of the biological relevance of aberrant isoforms of genes involved in the regulation of apoptosis (e. g. BCL-X, MCL-1, FAS, and c-FLIP), activation of key cellular signaling pathways (CASP8, MAP3K7, and NOTCH2), and cell metabolism (PKM).

GPATCH8 modulates mutant SF3B1 mis-splicing and pathogenicity in hematologic malignancies

Mutations in the RNA splicing factor gene SF3B1 are common across hematologic and solid cancers and result in widespread alterations in splicing, yet there is currently no therapeutic means to correct this mis-splicing. Here, we utilize synthetic introns uniquely responsive to mutant SF3B1 to identify trans factors required for aberrant mutant SF3B1 splicing activity. This revealed the G-patch domain-containing protein GPATCH8 as required for mutant SF3B1-induced splicing alterations and impaired hematopoiesis. GPATCH8 is involved in quality control of branchpoint selection, interacts with the RNA helicase DHX15, and functionally opposes SURP and G-patch domain containing 1 (SUGP1), a G-patch protein recently implicated in SF3B1-mutant diseases. Silencing of GPATCH8 corrected one-third of mutant SF3B1-dependent splicing defects and was sufficient to improve dysfunctional hematopoiesis in SF3B1-mutant mice and primary human progenitors. These data identify GPATCH8 as a novel splicing factor required for mis-splicing by mutant SF3B1 and highlight the therapeutic impact of correcting aberrant splicing in SF3B1-mutant cancers.

Validation and comparison of 5th edition World Health Organization classification (WHO 2022) and International Consensus Classification proposals for MDS-SFB31

The criteria of myelodysplastic syndromes (MDS) with mutated SFB31 (MDS-SFB31) proposed by the 5th edition of the WHO classification (WHO 2022) and the International Consensus Classification (ICC) need validation. We analysed 125 consecutive MDS cases with SFB31 mutation or ring sideroblasts (RS) ≥15% without excess blasts. We found that SFB31-negative MDS with RS had significantly different clinical features and worse prognosis. According to WHO 2022, the detection of ≥15% RS may substitute for SF3B1 mutation and our analyses support this proposal for similar prognosis of two groups after excluding high-risk genetic features referred by WHO 2022. Patients with variant allele frequency (VAF) <10% SFB31 tend to have briefer survival, supporting the VAF 10% threshold of ICC. Patients with multilineage dysplasia (MLD) had significantly shorter OS than those with single lineage dysplasia. MLD is still a powerful morphological marker of worse outcome in WHO 2022 and ICC-defined MDS-SF3B1.

A Brief Overview of the Molecular Landscape of Myelodysplastic Neoplasms

Myelodysplastic neoplasm (MDS) is a heterogeneous group of clonal hematological disorders that originate from the hematopoietic and progenitor cells and present with cytopenias and morphologic dysplasia with a propensity to progress to bone marrow failure or acute myeloid leukemia (AML). Genetic evolution plays a critical role in the pathogenesis, progression, and clinical outcomes of MDS. This process involves the acquisition of genetic mutations in stem cells that confer a selective growth advantage, leading to clonal expansion and the eventual development of MDS. With the advent of next-generation sequencing (NGS) assays, an increasing number of molecular aberrations have been discovered in recent years. The knowledge of molecular events in MDS has led to an improved understanding of the disease process, including the evolution of the disease and prognosis, and has paved the way for targeted therapy. The 2022 World Health Organization (WHO) Classification and the International Consensus Classification (ICC) have incorporated the molecular signature into the classification system for MDS. In addition, specific germline mutations are associated with MDS development, especially in pediatrics and young adults. This article reviews the genetic abnormalities of MDS in adults with a brief review of germline predisposition syndromes.

Role of reactive oxygen species in myelodysplastic syndromes

Reactive oxygen species (ROS) serve as typical metabolic byproducts of aerobic life and play a pivotal role in redox reactions and signal transduction pathways. Contingent upon their concentration, ROS production not only initiates or stimulates tumorigenesis but also causes oxidative stress (OS) and triggers cellular apoptosis. Mounting literature supports the view that ROS are closely interwoven with the pathogenesis of a cluster of diseases, particularly those involving cell proliferation and differentiation, such as myelodysplastic syndromes (MDS) and chronic/acute myeloid leukemia (CML/AML). OS caused by excessive ROS at physiological levels is likely to affect the functions of hematopoietic stem cells, such as cell growth and self-renewal, which may contribute to defective hematopoiesis. We review herein the eminent role of ROS in the hematological niche and their profound influence on the progress of MDS. We also highlight that targeting ROS is a practical and reliable tactic for MDS therapy.

Accelerated DNA replication fork speed due to loss of R-loops in myelodysplastic syndromes with SF3B1 mutation

Myelodysplastic syndromes (MDS) with mutated SF3B1 gene present features including a favourable outcome distinct from MDS with mutations in other splicing factor genes SRSF2 or U2AF1. Molecular bases of these divergences are poorly understood. Here we find that SF3B1-mutated MDS show reduced R-loop formation predominating in gene bodies associated with intron retention reduction, not found in U2AF1- or SRSF2-mutated MDS. Compared to erythroblasts from SRSF2- or U2AF1-mutated patients, SF3B1-mutated erythroblasts exhibit augmented DNA synthesis, accelerated replication forks, and single-stranded DNA exposure upon differentiation. Importantly, histone deacetylase inhibition using vorinostat restores R-loop formation, slows down DNA replication forks and improves SF3B1-mutated erythroblast differentiation. In conclusion, loss of R-loops with associated DNA replication stress represents a hallmark of SF3B1-mutated MDS ineffective erythropoiesis, which could be used as a therapeutic target.

Myelodysplastic Neoplasms (MDS) with Ring Sideroblasts or SF3B1 Mutations: The Improved Clinical Utility of World Health Organization and International Consensus Classification 2022 Definitions, a Single-Centre Retrospective Chart Review

Myelodysplastic neoplasms (MDS) with ring sideroblasts (RS) are diagnosed via bone marrow aspiration in the presence of either (i) ≥15% RS or (ii) 5-14% RS and an SF3B1 mutation. In the MEDALIST trial and in an interim analysis of the COMMANDS trial, lower-risk MDS-RS patients had decreased transfusion dependency with luspatercept treatment. A total of 6817 patients with suspected hematologic malignancies underwent molecular testing using a next-generation-sequencing-based genetic assay and 395 MDS patients, seen at our centre from 1 January 2018 to 31 May 2023, were reviewed. Of these, we identified 39 evaluable patients as having lower-risk MDS with SF3B1 mutations: there were 20 (51.3%) males and 19 (48.7%) females, with a median age of 77 years (range of 57 to 92). Nineteen (48.7%) patients had an isolated SF3B1 mutation with a mean variant allele frequency of 35.2% +/- 8.1%, ranging from 7.4% to 46.0%. There were 29 (74.4%) patients with ≥15% RS, 6 (15.4%) with 5 to 14% RS, one (2.6%) with 1% RS, and 3 (7.7%) with no RS. Our study suggests that a quarter of patients would be missed based on the morphologic criterion of only using RS greater than 15% and supports the revised 2022 definitions of the World Health Organization (WHO) and International Consensus Classification (ICC), which shift toward molecularly defined subtypes of MDS and appropriate testing.

Targeting the Warburg effect: A revisited perspective from molecular mechanisms to traditional and innovative therapeutic strategies in cancer

Cancer reprogramming is an important facilitator of cancer development and survival, with tumor cells exhibiting a preference for aerobic glycolysis beyond oxidative phosphorylation, even under sufficient oxygen supply condition. This metabolic alteration, known as the Warburg effect, serves as a significant indicator of malignant tumor transformation. The Warburg effect primarily impacts cancer occurrence by influencing the aerobic glycolysis pathway in cancer cells. Key enzymes involved in this process include glucose transporters (GLUTs), HKs, PFKs, LDHs, and PKM2. Moreover, the expression of transcriptional regulatory factors and proteins, such as FOXM1, p53, NF-κB, HIF1α, and c-Myc, can also influence cancer progression. Furthermore, lncRNAs, miRNAs, and circular RNAs play a vital role in directly regulating the Warburg effect. Additionally, gene mutations, tumor microenvironment remodeling, and immune system interactions are closely associated with the Warburg effect. Notably, the development of drugs targeting the Warburg effect has exhibited promising potential in tumor treatment. This comprehensive review presents novel directions and approaches for the early diagnosis and treatment of cancer patients by conducting in-depth research and summarizing the bright prospects of targeting the Warburg effect in cancer.

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.

The clinical, molecular, and prognostic features of the 2022 WHO and ICC classification systems for myelodysplastic neoplasms

Myelodysplastic neoplasms (MDS) are clonal disorders of bone marrow failure exhibiting a variable risk of progression to acute myeloid leukemia. MDS exhibit certain prognostic genetic or cytogenetic abnormalities, an observation that has led to both the pathologic reclassification of MDS in the 2022 World Health Organization (WHO) and International Consensus Classification (ICC) systems, as well as to an updated prognostic schema, the Molecular International Prognostic Scoring System (IPSS-M). This single-institution study characterized the molecular patterns and clinical outcomes associated with the 2022 WHO and ICC classification schemas to assess their clinical utility. Strikingly, with the exception of one individual, all 210 patients in our cohort were classified into analogous categories by the two pathologic/diagnostic schemas. Most patients (70%) were classified morphologically while the remaining 30% had genetically classified disease by both criteria. Prognostic risk, as assessed by the IPSS-M score was highest in patients with MDS with biallelic/multi-hit TP53 mutations and lowest in pts with MDS-SF3B1. Median leukemia-free survival (LFS) was shortest for those with MDS with biallelic/multi-hit TP53 (0.7 years) and longest for those with MDS with low blasts (LFS not reached). These data demonstrate the clear ability of the 2022 WHO and ICC classifications to organize MDS patients into distinct prognostic risk groups and further show that both classification systems share more similarities than differences. Incorporation of the IPSS-M and IPSS-R features provide additive prognostic and survival components to both the WHO and ICC classifications, which together enhance their utility for evaluating and treating MDS patients.

Hypomethylating agents (HMAs) show benefit in AML rather than in intermediate/high-risk MDS based on genetic mutations in epigenetic modification (EMMs): from a retrospective study

Since HMAs were recommended for treatments in AML and MDS, we wondered whether HMAs could provide similar benefit to AML and intermediate/high-risk MDS under the direction of next-generation sequencing. Here we retrospectively analyzed the prognosis of 176 AML and 128 intermediate/high-risk MDS patients treated with HMAs or non-HMA regimens. For AML, HMAs regimen was related to better CR rate compared with non-HMA regimen in elder cohort, while the situation was the opposite in younger cohort. In consolidation phase, EMM (+) patients could benefit from HMAs regimen. Relapsed AML patients receiving HMAs regimen rather than non-HMA regimen had better post-relapse survival. Multivariate analysis identified HMA regimen as an independent prognostic factor for OS in EMM (+) cohort. For intermediate/high-risk MDS patients not undergoing HSCT, however, HMA regimen showed no survival advantage in EMM (+) cohort and was conversely associated with shorter survival in EMM (-) cohort compared with non-HMA regimen. And among those undergoing HSCT, HMA prior to HSCT predicted poor prognosis compared with upfront HSCT regardless of the existence of EMMs. Therefore, HMAs had better therapeutic value in AML rather than in intermediate/high-risk MDS based on EMMs.

Recent advances in the application of induced pluripotent stem cell technology to the study of myeloid malignancies

Acquired myeloid malignancies are a spectrum of clonal disorders known to be caused by sequential acquisition of genetic lesions in hematopoietic stem and progenitor cells, leading to their aberrant self-renewal and differentiation. The increasing use of induced pluripotent stem cell (iPSC) technology to study myeloid malignancies has helped usher a paradigm shift in approaches to disease modeling and drug discovery, especially when combined with gene-editing technology. The process of reprogramming allows for the capture of the diversity of genetic lesions and mutational burden found in primary patient samples into individual stable iPSC lines. Patient-derived iPSC lines, owing to their self-renewal and differentiation capacity, can thus be a homogenous source of disease relevant material that allow for the study of disease pathogenesis using various functional read-outs. Furthermore, genome editing technologies like CRISPR/Cas9 enable the study of the stepwise progression from normal to malignant hematopoiesis through the introduction of specific driver mutations, individually or in combination, to create isogenic lines for comparison. In this review, we survey the current use of iPSCs to model acquired myeloid malignancies including myelodysplastic syndromes (MDS), myeloproliferative neoplasms (MPN), acute myeloid leukemia and MDS/MPN overlap syndromes. The use of iPSCs has enabled the interrogation of the underlying mechanism of initiation and progression driving these diseases. It has also made drug testing, repurposing, and the discovery of novel therapies for these diseases possible in a high throughput setting.

Acute Myeloid Leukemia Arising from Myelodysplastic Syndromes

Myelodysplastic syndromes (MDS) are a group of myeloid neoplasms characterized by clonal hematopoiesis and abnormal maturation of hematopoietic cells, resulting in cytopenias. The transformation of MDS to acute myeloid leukemia (AML) reflects a progressive increase in blasts due to impaired maturation of the malignant clone, and thus MDS and many AML subtypes form a biological continuum rather than representing two distinct diseases. Recent data suggest that, in addition to previously described translocations, NPM1 mutations and KMT2A rearrangements are also AML-defining genetic alterations that lead to rapid disease progression, even if they present initially with less than  20% blasts. While some adult patients <20% blasts can be treated effectively with intensive AML-type chemotherapy, in the future, treatment of individual patients in this MDS/AML group will likely be dictated by genetic, biological, and patient-related factors rather than an arbitrary blast percentage.

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.

Morphologic Characteristics of Myelodysplastic Syndromes

Morphologic characterization remains a cornerstone in the diagnosis and classification of myelodysplastic syndromes (MDS) in the updated International Consensus Classification (ICC) and 5th edition World Health Organization Classification of Myeloid Neoplasms (Arber, Orazi, & Hasserjian, 2022; Khoury & Solary, 2022). The presence of dysplasia is one of the key diagnostic criteria required for establishing a diagnosis of MDS, and the percentage of myeloblasts in the blood and bone marrow impacts both disease classification and prognostication. Morphologic features also aid in distinguishing MDS from a myriad of other myeloid neoplasms and non-neoplastic mimics. Additional key morphologic features that should be recorded in any MDS case are the bone marrow cellularity and the degree of reticulin fibrosis. In this review, the morphologic assessment of the bone marrow biopsy, bone marrow aspirate, and peripheral blood smear as it pertains to the diagnosis and up-to-date classification of MDS will be described. The implications of the findings on classification and prognosis will also be discussed.

Targeted NGS on sequential bone marrow biopsies aids in the evaluation of cytopenias and monocytosis and documents clonal evolution-a proof of principle study

Differential diagnosis of clonal versus reactive cytopenia and monocytosis, respectively, frequently presents a diagnostic challenge. With the two recent classifications of myeloid disorders, mutational analysis has gained importance as a diagnostic tool. However, reports on its utility on trephine bone marrow biopsies (BMB) are sparse. The aim of our proof of principle study was to determine the suitability of targeted sequencing for the longitudinal evaluation of cytopenia and monocytosis and demonstration of clonal evolution on sequential BMB. Seventy-seven EDTA-decalcified BMB of 33 patients with peripheral cytopenia and/or monocytosis, including at least one follow-up biopsy/patient, were included. Initial morphological diagnoses were idiopathic cytopenia of undetermined significance (ICUS, 8 cases), MDS (without blast increase, 7 cases), MDS with increased blasts/excess blasts (MDS-IB/EB) (11 cases), and CMML (7 cases). Thirty-one genes relevant for myeloid disorders were examined using two custom AmpliSeq NGS panels. Mutations were found in the initial BMB of 5/8 cases of ICUS, thus changing the diagnosis to clonal cytopenia of unknown significance (CCUS), 5/7 MDS, 10/11 MDS-IB/EB, and 7/7 CMML. Clonal evolution was observed in 14/33 (42%) cases, mostly associated with disease progression. None of the wild-type patients acquired mutations during follow-up. NGS-based mutation profiling is a robust diagnostic tool for BMB and provides valuable additional information, especially for cases with no/minimal dysplasia, and for better risk stratification of MDS. Tracking variant allele frequency and appearance of mutations over time allows for observing clonal evolution or relapse.

Deep immunophenotypic analysis of the bone marrow progenitor cells in myelodysplastic syndromes

BACKGROUND

Diagnosis of myelodysplastic syndromes (MDS) is often challenging and requires integration of clinical, morphologic, cytogenetics and molecular information. Flow cytometry immunophenotyping (FCIP) can support the diagnosis by demonstration of numerical and immunophenotypic abnormalities of progenitor and maturing myelomonocytic and erythroid populations. We have previously shown that comprehensive immunophenotypic analysis of the progenitor population is valuable in the diagnosis of MDS and myelodysplastic/myeloproliferative neoplasms (MDS/MPN). This study was designed to improve the analysis method and confirm its value in a larger cohort of patients.

METHODS

FCIP of bone marrow samples from 105 patients with cytopenia(s) (with or without leukocytosis) and clinical concern for MDS or MDS/MPN was performed using a single-tube/10-color/13-marker assay. A modified analysis approach was used to obtain 11 progenitor parameters and 2 myelomonocytic parameters.

RESULTS

Significantly higher number of abnormalities were identified in MDS and MDS/MPN cases when compared to cytopenic patients not meeting the diagnostic criteria for MDS (Non-MDS). A FCIP score that combined the 13 parameters showed a sensitivity of 89.8% and specificity of 93.5% for the diagnosis of MDS and MDS/MPN. The sensitivity was 100% for both MDS/MPN and higher-risk MDS, and 81.3% for lower-risk MDS.

CONCLUSION

This study confirms that detailed immunophenotypic analysis of the progenitor population is powerful in the diagnosis of MDS and MDS/MPN. The combination of markers used in the panel allowed for evaluation of two relatively new parameters, namely myeloid progenitor heterogeneity and stem cell aberrancy, which improved the sensitivity of the assay for lower-risk MDS.

Phenotypic clues that predict underlying cytogenetic/genetic abnormalities in myeloid malignancies: A contemporary review

Precise subclassification of myeloid malignancies per the World Health Organization (WHO) classification system and the International Consensus Classification of Myeloid Neoplasms and Acute Leukaemias (ICC) requires investigation and documentation of the presence of cytogenetic and/or molecular genetic changes. These ancillary studies not only help in diagnosis, but also the prognosis of disease; however, they take time to be completed. In contrast, morphological evaluation of material from the blood and bone marrow specimens of cases where myeloid malignancies are suspected is usually completed quickly. Cytomorphological assessment may predict genetic changes and can be helpful in triaging acuity. This is especially true in haematological emergencies such as acute promyelocytic leukaemia (APL), where prompt APL-specific therapy can be life changing. Similarly, some morphological clues may help identify core binding factor leukaemias where a diagnosis of acute myeloid leukaemia (AML) could be rendered without reaching the 20% blast cutoff with immediate treatment-decision implications, or even a subset of cases of AML with FLT3 ITD/NPM1 mutation(s) which show characteristic features. Even though FISH/cytogenetics and/or PCR are still required for establishing the final diagnosis, evaluation for the presence of specific cytomorphological features that help predict genetic changes can be a useful tool to help guide early therapy.

Integrated Genomic and Transcriptomic Analysis Improves Disease Classification and Risk Stratification of MDS with Ring Sideroblasts

PURPOSE

Ring sideroblasts (RS) define the low-risk myelodysplastic neoplasm (MDS) subgroup with RS but may also reflect erythroid dysplasia in higher risk myeloid neoplasm. The benign behavior of MDS with RS (MDSRS+) is limited to SF3B1-mutated cases without additional high-risk genetic events, but one third of MDSRS+ carry no SF3B1 mutation, suggesting that different molecular mechanisms may underlie RS formation. We integrated genomic and transcriptomic analyses to evaluate whether transcriptome profiles may improve current risk stratification.

EXPERIMENTAL DESIGN

We studied a prospective cohort of MDSRS+ patients irrespective of World Health Organization (WHO) class with regard to somatic mutations, copy-number alterations, and bone marrow CD34+ cell transcriptomes to assess whether transcriptome profiles add to prognostication and provide input on disease classification.

RESULTS

SF3B1, SRSF2, or TP53 multihit mutations were found in 89% of MDSRS+ cases, and each mutation category was associated with distinct clinical outcome, gene expression, and alternative splicing profiles. Unsupervised clustering analysis identified three clusters with distinct hemopoietic stem and progenitor (HSPC) composition, which only partially overlapped with mutation groups. IPSS-M and the transcriptome-defined proportion of megakaryocyte/erythroid progenitors (MEP) independently predicted survival in multivariable analysis.

CONCLUSIONS

These results provide essential input on the molecular basis of SF3B1-unmutated MDSRS+ and propose HSPC quantification as a prognostic marker in myeloid neoplasms with RS.

Mutational Profile Enables the Identification of a High-Risk Subgroup in Myelodysplastic Syndromes with Isolated Trisomy 8

Trisomy 8 (+8) is the most frequent trisomy in myelodysplastic syndromes (MDS) and is associated with clinical heterogeneity and intermediate cytogenetic risk when found in isolation. The presence of gene mutations in this group of patients and the prognostic significance has not been extensively analyzed. Targeted deep sequencing was performed in a cohort of 79 MDS patients showing isolated +8. The most frequently mutated genes were: TET2 (38%), STAG2 (34.2%), SRSF2 (29.1%) and RUNX1 (26.6%). The mutational profile identified a high-risk subgroup with mutations in STAG2, SRSF2 and/or RUNX1, resulting in shorter time to acute myeloid leukemia progression (14 months while not reached in patients without these mutations, p < 0.0001) and shorter overall survival (23.7 vs. 46.3 months, p = 0.001). Multivariate analyses revealed the presence of mutations in these genes as an independent prognostic factor in MDS showing +8 isolated (HR: 3.1; p < 0.01). Moreover, 39.5% and 15.4% of patients classified as low/intermediate risk by the IPSS-R and IPSS-M, respectively, were re-stratified as a high-risk subgroup based on the mutational status of STAG2, SRSF2 and RUNX1. Results were validated in an external cohort (n = 2494). In summary, this study validates the prognosis significance of somatic mutations shown in IPSS-M and adds STAG2 as an important mutated gene to consider in this specific subgroup of patients. The mutational profile in isolated +8 MDS patients could, therefore, offer new insights for the correct management of patients with a higher risk of leukemic transformation.

Computational analysis of peripheral blood smears detects disease-associated cytomorphologies

Many hematological diseases are characterized by altered abundance and morphology of blood cells and their progenitors. Myelodysplastic syndromes (MDS), for example, are a group of blood cancers characterised by cytopenias, dysplasia of hematopoietic cells and blast expansion. Examination of peripheral blood slides (PBS) in MDS often reveals changes such as abnormal granulocyte lobulation or granularity and altered red blood cell (RBC) morphology; however, some of these features are shared with conditions such as haematinic deficiency anemias. Definitive diagnosis of MDS requires expert cytomorphology analysis of bone marrow smears and complementary information such as blood counts, karyotype and molecular genetics testing. Here, we present Haemorasis, a computational method that detects and characterizes white blood cells (WBC) and RBC in PBS. Applied to over 300 individuals with different conditions (SF3B1-mutant and SF3B1-wildtype MDS, megaloblastic anemia, and iron deficiency anemia), Haemorasis detected over half a million WBC and millions of RBC and characterized their morphology. These large sets of cell morphologies can be used in diagnosis and disease subtyping, while identifying novel associations between computational morphotypes and disease. We find that hypolobulated neutrophils and large RBC are characteristic of SF3B1-mutant MDS. Additionally, while prevalent in both iron deficiency and megaloblastic anemia, hyperlobulated neutrophils are larger in the latter. By integrating cytomorphological features using machine learning, Haemorasis was able to distinguish SF3B1-mutant MDS from other MDS using cytomorphology and blood counts alone, with high predictive performance. We validate our findings externally, showing that they generalize to other centers and scanners. Collectively, our work reveals the potential for the large-scale incorporation of automated cytomorphology into routine diagnostic workflows.

Current landscape of translational and clinical research in myelodysplastic syndromes/neoplasms (MDS): Proceedings from the 1st International Workshop on MDS (iwMDS) Of the International Consortium for MDS (icMDS)

Biological events that contribute to the pathogenesis of myelodysplastic syndromes/neoplasms (MDS) are becoming increasingly characterized and are being translated into rationally designed therapeutic strategies. Herein, we provide updates from the first International Workshop on MDS (iwMDS) of the International Consortium for MDS (icMDS) detailing recent advances in understanding the genetic landscape of MDS, including germline predisposition, epigenetic and immune dysregulation, the complexities of clonal hematopoiesis progression to MDS, as well as novel animal models of the disease. Connected to this progress is the development of novel therapies targeting specific molecular alterations, the innate immune system, and immune checkpoint inhibitors. While some of these agents have entered clinical trials (e.g., splicing modulators, IRAK1/4 inhibitors, anti-CD47 and anti-TIM3 antibodies, and cellular therapies), none have been approved for MDS. Additional preclinical and clinical work is needed to develop a truly individualized approach to the care of MDS patients.

Assessment and validation of the molecular international prognostic scoring system for myelodysplastic syndromes

The Molecular International Prognostic Scoring System (IPSS-M) is a novel risk stratification model for myelodysplastic syndromes (MDS) that builds on the IPSS and IPSS-R by incorporating mutational data. The model showed improved prognostic accuracy over the IPSS-R across three endpoints: overall survival (OS), leukemia-free survival (LFS) and leukemic transformation. This study aimed to validate the findings of the original in a large cohort of MDS patients, as well as assess its validity in therapy-related and hypoplastic MDS. We retrospectively reviewed clinical, cytogenetic and molecular data for 2355 MDS patients treated at the Moffitt Cancer Center. Correlative analysis between IPSS-R and mean IPSS-M scores and outcome predictions was performed on LFS, OS and leukemic transformation. Using the IPSS-M, patients were classified as Very Low (4%), Low (24%), Moderate-Low (14%), Moderate-High (11%), High (19%) and Very-High risk (28%). Median OS was 11.7, 7.1, 4.4, 3.1, 2.3, and 1.3 years from VL to VH risk subgroups. Median LFS was 12.3, 6.9, 3.6, 2.2, 1.4, and 0.5 years respectively. For patients with t-MDS and h-MDS the model retained its prognostic accuracy. Generalized use of this tool will likely result in more accurate prognostic assessment and optimize therapeutic decision-making in MDS.

The Times, They Are A-Changing: The Impact of Next-Generation Sequencing on Diagnosis, Classification, and Prognostication of Myeloid Malignancies With Focus on Myelodysplastic Syndrome, AML, and Germline Predisposition

Myeloid malignancies are a manifestation of clonal expansion of hematopoietic cells driven by somatic genetic alterations that may arise in a potential background of deleterious germline variants. As next-generation sequencing technology has become more accessible, real-world experience has allowed integration of molecular genomic data with morphology, immunophenotype, and conventional cytogenetics to refine our understanding of myeloid malignancies. This has prompted revisions in the classification and the prognostication schema of myeloid malignancies and germline predisposition to hematologic malignancies. This review provides an overview of significant changes in the recently published classifications of AML and myelodysplastic syndrome, emerging prognostic scoring, and the role of germline deleterious variants in predisposing to MDS and AML.

Impact of the International Consensus Classification of myelodysplastic syndromes

The impact of the 2022 International Consensus Classification (ICC) of myelodysplastic syndromes (MDS) needs study. We analysed data from 989 MDS subjects classified using the 2016 World Health Organization (WHO) criteria to determine the impact of the new proposal. Our analyses suggested the ICC criteria of MDS-SF3B1 identifies a more homogenous disease entity than the WHO 2016 criteria of myelodysplastic syndromes with ring sideroblasts (MDS-RS). MDS, not otherwise specified with single lineage dysplasia (MDS, NOS-SLD) patients had a better prognosis than MDS, NOS with multilineage dysplasia (MDS, NOS-MLD) patients. MDS with mutated TP53 and MDS/acute myeloid leukaemia with mutated TP53 patients had the briefest survivals. These data support the ICC of MDS, which allows more accurate diagnoses and risk stratification.

A deep dive into future therapies for microcytic anemias and clinical considerations

INTRODUCTION

Microcytic anemias (MA) have frequent or rare etiologies. New discoveries in understanding and treatment of microcytic anemias need to be reviewed.

AREAS COVERED

Microcytic anemias with a focus on most frequent causes and on monogenic diseases that are relevant for understanding biocellular mechanisms of MA. All treatments excepting gene therapy, with a focus on recent advances. Pubmed search with references selected by expert opinion.

EXPERT OPINION

As the genetic and cellular background of dyserythropoiesis will continue to be clarified, collaboration with bioengineering of treatments acting specifically at the protein domain level will continue to provide new therapies in haematology as well as oncology and neurology.

CHIPing away the progression potential of CHIP: A new reality in the making

Over the past few years, we have gained a deeper understanding of clonal hematopoiesis of indeterminate potential (CHIP), especially with regard to the epidemiology, clinical sequelae, and mechanical aspects. However, interventional strategies to prevent or delay the potential negative consequences of CHIP remain underdeveloped. In this review, we highlight the latest updates on clonal hematopoiesis research, including molecular mechanisms and clinical implications, with a particular focus on the evolving strategies for the interventions that are being evaluated in ongoing observational and interventional trials. There remains an urgent need to formulate standardized and evidence-based recommendations and guidelines for evaluating and managing individuals with clonal hematopoiesis. In addition, patient-centric endpoints must be defined for clinical trials, which will enable us to continue the robust development of effective preventive strategies and improve clinical outcomes.

SOHO State of the Art Updates and Next Questions: Treatment of Lower Risk Myelodysplastic Syndromes

MDS is a clonal stem cell neoplasm with a spectrum from lower risk disease to short term life threatening higher risk disease. The disease risk is dictated by clinical and molecular features. Majority of MDS patients including lower risk disease unfortunately succumb from disease related complications namely cytopenia. While cytopenias may be mild early upon diagnosis and can be surveilled, ultimately treatment is required. Anemia is the hall mark of disease and most common indication to treat in lower risk MDS. Erythroid stimulating agents are used in the first line setting. Treatment can be a personalized approach as in select patient such as patients with del(5q) and those with ringed sideroblasts, lenalidomide, and luspatercept can be extremely effective respectively at improving cytopenias. Younger patients and hypoplastic MDS have also shown and improved response to immunosuppressive therapy. Hypomethylating agents can be option for patients with higher risk features or thrombocytopenia/neutropenia. Refractory cytopenias still poses frustration as options are limited and there is need to add more treatments to our armamentarium.

Impact of gene alterations on clinical outcome in young adults with myelodysplastic syndromes

Young adults with myelodysplastic syndrome (MDS) are rare, and the clinical significance of driver mutations has not yet been analysed. We analysed the gene mutations and copy number alterations (CNAs) in younger MDS patients using next-generation sequencing, targeting 68 genes that were recurrently mutated in myeloid malignancies, to investigate the correlation between their genetic alterations and clinical outcomes. We enrolled 55 patients retrospectively (aged < 50 years). At least one mutation was detected in 56% of the patients. The most frequently mutated genes were ASXL1 and RUNX1, 13% each. We defined higher-risk patients as those with ≥ 2 mutations, except for SF3B1 mutation, and/or CNA. The 3-year overall survival (OS) in patients with a higher-risk was lower than that in those with a lower-risk (50.8% vs. 71.8%, P = 0.024). Among the 44 transplant recipients, patients with higher-risk had a significantly lower OS and tended to have a higher cumulative incidence of relapse (CIR) than those with a lower-risk (3-year OS: 38.0% vs. 64.4%, P = 0.039; 3-year CIR: 44.0% vs. 24.1%, P = 0.076). Our results showed that genetic aberrations can predict clinical outcomes in younger MDS patients, despite the low rate of genetic mutations.

Comparison of demographics, disease characteristics, and outcomes between Black and White patients with myelodysplastic syndromes: A population-based study

Racial disparities in cancer care and outcomes have been well documented in various malignancies, with Black patients having the highest death rate and shortest survival of any racial/ethnic group in the United States (US) for most cancers. However, there have been limited studies on racial/ethnic disparities in myelodysplastic syndromes (MDS). Our study characterized and compared differences in baseline demographics, clinical characteristics, socioeconomic factors, and overall survival (OS) between Black and White patients with MDS in the US. We used the Surveillance, Epidemiology, and End Results (SEER) Program and included 37,562 patients (Black, 8.1 %; White, 91.9 %) diagnosed between 2001 and 2013. We observed significant differences in baseline characteristics between cohorts. In a univariate analysis, Black race was associated with longer survival (hazard ratio [HR]: 0.83; 95 % confidence interval [CI], 0.79-0.86; p < 0.001). The association between race and survival was attenuated but remained significant in various models to adjust for differences in baseline characteristics (HR in multivariable analysis, 0.92; 95 % CI, 0.87-0.96); p < 0.001). Subgroup analysis by histology revealed differences in the association between race and OS. Refractory anemia (RA), RA with ring sideroblasts, and MDS-not otherwise specified, a category in SEER representing a poorly defined MDS subset for 52 % of cases in our study, favored Black patients. RA with excess blasts favored White patients. The overall finding that Black race is associated with better OS outcomes, when compared with White patients, needs to be interpreted with caution and nuanced by histology. Additional research to explore these associations is warranted.

Allogeneic stem cell transplantation for patients with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are a heterogenous group of clonal hematopoietic stem cell neoplasms primarily affecting older persons, associated with dysplastic changes of bone marrow cells, peripheral cytopenias, and various risk of leukemic transformation. Although treatment with several drugs has shown improved disease control, allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains the only curative treatment for MDS. The number of patients receiving a transplant, as well as survival, have increased past years because of the use of reduce-intensity conditioning regimens (RIC) as well as the use of haploidentical donors for transplantation. With treatment-related mortality as main limitation, pre-transplant evaluation is essential to assess risks for this older group of patients. In a recent randomized study, allo-HSCT with RIC for patients >50 years old with higher-risk MDS demonstrated superiority in survival compared with hypomethylating agents. Genetic mutations have been shown to significantly impact treatment outcomes including after transplant. Recently, a transplant-specific risk score (which includes age, donor type, performance status, cytogenetic category, recipient's cytomegalovirus status, percentage of blasts, and platelet count) has shown superiority in transplantation outcome prediction, compared with previous scoring systems. Survival remains low for most patients with TP53 mutations and novel treatment strategies are needed, such as administration of natural killer cells post-transplant, as there is no clear evidence that maintenance therapy after transplantation can improve outcomes.

The International Consensus Classification of myelodysplastic syndromes and related entities

The International Consensus Classification (ICC) of myeloid neoplasms and acute leukemia has updated the classification of myelodysplastic syndromes (MDSs) and placed MDS in a broader group of clonal cytopenias that includes clonal cytopenia of undetermined significance (CCUS) and related entities. Although subject to some interobserver variability and lack of specificity, morphologic dysplasia remains the main feature that distinguishes MDS from other clonal cytopenias and defines MDS as a hematologic malignancy. The ICC has introduced some changes in the definition of MDS whereby some cases categorized as MDS based on cytogenetic abnormalities are now classified as CCUS, while SF3B1 and multi-hit TP53 mutations are now considered to be MDS-defining in a cytopenic patient. The ICC has also recognized several cytogenetic and molecular abnormalities that reclassify some cases of MDS with excess blasts as acute myeloid leukemia (AML) and has introduced a new MDS/AML entity that encompasses cases with 10-19% blasts that lie on the continuum between MDS and AML. Two new genetically defined categories of MDS have been introduced: MDS with mutated SF3B1 and MDS with mutated TP53, the latter requiring bi-allelic aberrations in the TP53 gene. The entity MDS, unclassifiable has been eliminated. These changes have resulted in an overall simplification of the MDS classification scheme from 8 separate entities (including 1 that was genetically defined) in the revised 4th edition WHO classification to 7 separate entities (including 3 that are genetically defined) in the ICC.

Splicing factor mutations in the myelodysplastic syndromes: Role of key aberrantly spliced genes in disease pathophysiology and treatment

Mutations of splicing factor genes (including SF3B1, SRSF2, U2AF1 and ZRSR2) occur in more than half of all patients with myelodysplastic syndromes (MDS), a heterogeneous group of myeloid neoplasms. Splicing factor mutations lead to aberrant pre-mRNA splicing of many genes, some of which have been shown in functional studies to impact on hematopoiesis and to contribute to the MDS phenotype. This clearly demonstrates that impaired spliceosome function plays an important role in MDS pathophysiology. Recent studies that harnessed the power of induced pluripotent stem cell (iPSC) and CRISPR/Cas9 gene editing technologies to generate new iPSC-based models of splicing factor mutant MDS, have further illuminated the role of key downstream target genes. The aberrantly spliced genes and the dysregulated pathways associated with splicing factor mutations in MDS represent potential new therapeutic targets. Emerging data has shown that IRAK4 is aberrantly spliced in SF3B1 and U2AF1 mutant MDS, leading to hyperactivation of NF-κB signaling. Pharmacological inhibition of IRAK4 has shown efficacy in pre-clinical studies and in MDS clinical trials, with higher response rates in patients with splicing factor mutations. Our increasing knowledge of the effects of splicing factor mutations in MDS is leading to the development of new treatments that may benefit patients harboring these mutations.

Erythropoiesis in lower-risk myelodysplastic syndromes and beta-thalassemia

The hematologic disorders myelodysplastic syndromes and beta-thalassemia are characterized by ineffective erythropoiesis and anemia, often managed with regular blood transfusions. Erythropoiesis, the process by which sufficient numbers of functional erythrocytes are produced from hematopoietic stem cells, is highly regulated, and defects can negatively affect the proliferation, differentiation, and survival of erythroid precursors. Treatments that directly target the underlying mechanisms of ineffective erythropoiesis are limited, and management of anemia with regular blood transfusions imposes a significant burden on patients, caregivers, and health care systems. There is therefore a strong unmet need for treatments that can restore effective erythropoiesis. Novel therapies are beginning to address this need by targeting a variety of mechanisms underlying erythropoiesis. Herein, we provide an overview of the role of ineffective erythropoiesis in myelodysplastic syndromes and beta-thalassemia, discuss unmet needs in targeting ineffective erythropoiesis, and describe current management strategies and emerging treatments for these disorders.

Comparison of the revised 4th (2016) and 5th (2022) editions of the World Health Organization classification of myelodysplastic neoplasms

We used data from 852 consecutive subjects with myelodysplastic neoplasms (MDS) diagnosed according to the 2016 (revised 4th) World Health Organization (WHO) criteria to evaluate the 2022 (5th) edition WHO classification of MDS. 30 subjects previously classified as MDS with an NPM1 mutation were re-classified as acute myeloid leukaemia (AML). 9 subjects previously classified as MDS-U were re-classified to clonal cytopenia of undetermined significance (CCUS). The remaining 813 subjects were diagnosed as: MDS-5q (N = 11 [1%]), MDS-SF3B1 (N = 70 [9%]), MDS-biTP53 (N = 53 [7%]), MDS-LB (N = 293 [36%]), MDS-h (N = 80 [10%]), MDS-IB1 (N = 161 [20%]), MDS-IB2 (N = 103 [13%]) and MDS-f (N = 42 [5%]) and MDS-biTP53 (N = 53 [7%]). 34 of these subjects came from the 53 (64%) MDS-biTP53 previously diagnosed as MDS-EB. Median survival of subjects classified as MDS using the WHO 2022 criteria was 45 months (95% Confidence Interval [CI], 34, 56 months). Subjects re-classified as MDS-biTP53 and MDS-f had significantly briefer median survivals compared with other MDS sub-types (10 months, [8, 12 months] and 15 months [8, 23 months]). In conclusion, our analyses support the refinements made in the WHO 2022 proposal.

SF3B1, RUNX1 and TP53 Mutations Significantly Impact the Outcome of Patients With Lower-Risk Myelodysplastic Syndrome

INTRODUCTION

Prognosis of patients with myelodysplastic syndrome (MDS), particularly the group with lower-risk disease (LR-MDS) is very heterogeneous. Several studies have described the prognostic value of recurrent somatic mutations in MDS including all risk categories. Recently, the incorporation of genomic data to clinical parameters defined the new Molecular International Prognostic Scoring System (IPSS-M).

MATERIALS AND METHODS

In this study, we evaluated the impact of molecular profile in a series of 181 patients with LR-MDS and non-proliferative chronic myelomonocytic leukemia.

RESULTS

Epigenetic regulators (TET2, ASXL1) and splicing (SF3B1) were the most recurrent mutated pathways. In univariate analysis, RUNX1 or TP53 mutations correlated with lower median overall survival (OS). In contrast, SF3B1 mutation was associated with prolonged median OS [95 months (95% IC, 32-157) vs. 33 months (95% CI, 19-46) in unmutated patients (P < 0.01)]. In a multivariate Cox regression model, RUNX1 mutations independently associated with shorter OS, while SF3B1 mutation retained its favorable impact on outcome (HR: 0.24, 95% CI, 0.1-0.5; P = 0.001). In addition, TP53 or RUNX1 mutations were identified as predictive covariates for the probability of leukemic progression (P < 0.001).

CONCLUSION

Incorporation of molecular testing in LR-MDS identified a subset of patients with expected poorer outcome, either due to lower survival or probability of leukemic progression.

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

Myelodysplastic syndromes (MDS) are a family of myeloid cancers with diverse genotypes and phenotypes characterized by ineffective haematopoiesis and risk of transformation to acute myeloid leukaemia (AML). Some epidemiological data indicate that MDS incidence is increasing in resource-rich regions but this is controversial. Most MDS cases are caused by randomly acquired somatic mutations. In some patients, the phenotype and/or genotype of MDS overlaps with that of bone marrow failure disorders such as aplastic anaemia, paroxysmal nocturnal haemoglobinuria (PNH) and AML. Prognostic systems, such as the revised International Prognostic Scoring System (IPSS-R), provide reasonably accurate predictions of survival at the population level. Therapeutic goals in individuals with lower-risk MDS include improving quality of life and minimizing erythrocyte and platelet transfusions. Therapeutic goals in people with higher-risk MDS include decreasing the risk of AML transformation and prolonging survival. Haematopoietic cell transplantation (HCT) can cure MDS, yet fewer than 10% of affected individuals receive this treatment. However, how, when and in which patients with HCT for MDS should be performed remains controversial, with some studies suggesting HCT is preferred in some individuals with higher-risk MDS. Advances in the understanding of MDS biology offer the prospect of new therapeutic approaches.

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.

Targeting the EIF2AK1 Signaling Pathway Rescues Red Blood Cell Production in SF3B1-Mutant Myelodysplastic Syndromes With Ringed Sideroblasts

SF3B1 mutations, which occur in 20% of patients with myelodysplastic syndromes (MDS), are the hallmarks of a specific MDS subtype, MDS with ringed sideroblasts (MDS-RS), which is characterized by the accumulation of erythroid precursors in the bone marrow and primarily affects the elderly population. Here, using single-cell technologies and functional validation studies of primary SF3B1-mutant MDS-RS samples, we show that SF3B1 mutations lead to the activation of the EIF2AK1 pathway in response to heme deficiency and that targeting this pathway rescues aberrant erythroid differentiation and enables the red blood cell maturation of MDS-RS erythroblasts. These data support the development of EIF2AK1 inhibitors to overcome transfusion dependency in patients with SF3B1-mutant MDS-RS with impaired red blood cell production.

SIGNIFICANCE

MDS-RS are characterized by significant anemia. Patients with MDS-RS die from a shortage of red blood cells and the side effects of iron overload due to their constant need for transfusions. Our study has implications for the development of therapies to achieve long-lasting hematologic responses. This article is highlighted in the In This Issue feature, p. 476.

Novel Therapies for Unmet Clinical Needs in Myelodysplastic Syndromes

Simple Summary

Several novel therapies are being developed to improve the management of patients with myelodysplastic syndromes. They include drugs aimed at improving hematopoiesis and differentiation of myeloid precursors, hypomethylating agents, several compounds that target intracellular molecular pathways, and immunotherapies. In this review article, we discuss how the novel drugs may address the several unmet needs of lower- and higher-risk patients.

Abstract

Myelodysplastic syndromes (MDS) are a very heterogeneous disease, with extremely variable clinical features and outcomes. Current management relies on risk stratification based on IPSS and IPSS-R, which categorizes patients into low (LR-) and high-risk (HR-) MDS. Therapeutic strategies in LR-MDS patients mainly consist of erythropoiesis stimulating agents (ESAs), transfusion support, and luspatercept or lenalidomide for selected patients. Current unmet needs include the limited options available after treatment failure, and the consequent transfusion burden with several hospital admissions and poor quality of life. Therapeutic approaches in HR-MDS patients are aimed at changing the natural course of the disease and hypometylating agents (HMA) are the first choice. The only potentially curative treatment is allogeneic stem cell transplant (allo-HCT), restricted to a minority of young and fit candidates. Patients unfit for or those that relapse after the abovementioned options harbor an adverse prognosis, with limited overall survival and frequent leukemic evolution. Recent advances in genetic mutations and intracellular pathways that are relevant for MDS pathogenesis are improving disease risk stratification and highlighting therapeutic targets addressed by novel agents. Several drugs are under evaluation for LR and HR patients, which differ by their mechanism of action, reported efficacy, and phase of development. This review analyzes the current unmet clinical needs for MDS patients and provides a critical overview of the novel agents under development in this setting.

Eprenetapopt triggers ferroptosis, inhibits NFS1 cysteine desulfurase, and synergizes with serine and glycine dietary restriction

The mechanism of action of eprenetapopt (APR-246, PRIMA-1^MET) as an anticancer agent remains unresolved, although the clinical development of eprenetapopt focuses on its reported mechanism of action as a mutant-p53 reactivator. Using unbiased approaches, this study demonstrates that eprenetapopt depletes cellular antioxidant glutathione levels by increasing its turnover, triggering a nonapoptotic, iron-dependent form of cell death known as ferroptosis. Deficiency in genes responsible for supplying cancer cells with the substrates for de novo glutathione synthesis (SLC7A11, SHMT2, and MTHFD1L), as well as the enzymes required to synthesize glutathione (GCLC and GCLM), augments the activity of eprenetapopt. Eprenetapopt also inhibits iron-sulfur cluster biogenesis by limiting the cysteine desulfurase activity of NFS1, which potentiates ferroptosis and may restrict cellular proliferation. The combination of eprenetapopt with dietary serine and glycine restriction synergizes to inhibit esophageal xenograft tumor growth. These findings reframe the canonical view of eprenetapopt from a mutant-p53 reactivator to a ferroptosis inducer.

Diagnosis and Treatment of Myelodysplastic Syndromes: A Review

IMPORTANCE

Myelodysplastic neoplasms (MDS), formerly known as myelodysplastic syndromes, are clonal hematopoietic malignancies that cause morphologic bone marrow dysplasia along with anemia, neutropenia, or thrombocytopenia. MDS are associated with an increased risk of acute myeloid leukemia (AML). The yearly incidence of MDS is approximately 4 per 100 000 people in the United States and is higher among patients with advanced age.

OBSERVATIONS

MDS are characterized by reduced numbers of peripheral blood cells, an increased risk of acute myeloid leukemia transformation, and reduced survival. The median age at diagnosis is approximately 70 years, and the yearly incidence rate increases to 25 per 100 000 in people aged 65 years and older. Risk factors associated with MDS include older age and prior exposures to toxins such as chemotherapy or radiation therapy. MDS are more common in men compared with women (with yearly incidence rates of approximately 5.4 vs 2.9 per 100 000). MDS typically has an insidious presentation, consisting of signs and symptoms associated with anemia, thrombocytopenia, and neutropenia. MDS can be categorized into subtypes that are associated with lower or higher risk for acute myeloid leukemia transformation and that help with therapy selection. Patients with lower-risk MDS have a median survival of approximately 3 to 10 years, whereas patients with higher-risk disease have a median survival of less than 3 years. Therapy for lower-risk MDS is selected based on whether the primary clinical characteristic is anemia, thrombocytopenia, or neutropenia. Management focuses on treating symptoms and reducing the number of required transfusions in patients with low-risk disease. For patients with lower-risk MDS, erythropoiesis stimulating agents, such as recombinant humanized erythropoietin or the longer-acting erythropoietin, darbepoetin alfa, can improve anemia in 15% to 40% of patients for a median of 8 to 23 months. For those with higher-risk MDS, hypomethylating agents such as azacitidine, decitabine, or decitabine/cedazuridine are first-line therapy. Hematopoietic cell transplantation is considered for higher-risk patients and represents the only potential cure.

CONCLUSIONS AND RELEVANCE

MDS are diagnosed in approximately 4 per 100 000 people in the United States and are associated with a 5-year survival rate of approximately 37%. Treatments are tailored to the patient's disease characteristics and comorbidities and range from supportive care with or without erythropoiesis-stimulating agents for patients with low-risk MDS to hypomethylating agents, such as azacitidine or decitabine, for patients with higher-risk MDS. Hematopoietic cell transplantation is potentially curative and should be considered for patients with higher-risk MDS at the time of diagnosis.