Mutational landscape of myelodysplastic/myeloproliferative neoplasm-unclassifiable

Genomic Landscape of Myelodysplastic/Myeloproliferative Neoplasms: A Multi-Central Study

The accurate diagnosis and classification of myelodysplastic/myeloproliferative neoplasm (MDS/MPN) are challenging due to the overlapping pathological and molecular features of myelodysplastic syndrome (MDS) and myeloproliferative neoplasm (MPN). We investigated the genomic landscape in different MDS/MPN subtypes, including chronic myelomonocytic leukemia (CMML; n = 97), atypical chronic myeloid leukemia (aCML; n = 8), MDS/MPN-unclassified (MDS/MPN-U; n = 44), and MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T; n = 12). Our study indicated that MDS/MPN is characterized by mutations commonly identified in myeloid neoplasms, with TET2 (52%) being the most frequently mutated gene, followed by ASXL1 (38.7%), SRSF2 (34.7%), and JAK2 (19.7%), among others. However, the distribution of recurrent mutations differs across the MDS/MPN subtypes. We confirmed that specific gene combinations correlate with specific MDS/MPN subtypes (e.g., TET2/SRSF2 in CMML, ASXL1/SETBP1 in aCML, and SF3B1/JAK2 in MDS/MPN-RS-T), with MDS/MPN-U being the most heterogeneous. Furthermore, we found that older age (≥65 years) and mutations in RUNX1 and TP53 were associated with poorer clinical outcomes in CMML (p < 0.05) by multivariate analysis. In MDS/MPN-U, CBL mutations (p < 0.05) were the sole negative prognostic factors identified in our study by multivariate analysis (p < 0.05). Overall, our study provides genetic insights into various MDS/MPN subtypes, which may aid in diagnosis and clinical decision-making for patients with MDS/MPN.

Myeloproliferative Neoplasms: Contemporary Review and Molecular Landscape

Myelofibrosis (MF), Myeloproliferative neoplasms (MPNs), and MDS/MPN overlap syndromes have a broad range of clinical presentations and molecular abnormalities, making their diagnosis and classification complex. This paper reviews molecular aberration, epigenetic modifications, chromosomal anomalies, and their interactions with cellular and other immune mechanisms in the manifestations of these disease spectra, clinical features, classification, and treatment modalities. The advent of new-generation sequencing has broadened the understanding of the genetic factors involved. However, while great strides have been made in the pharmacological treatment of these diseases, treatment of advanced disease remains hematopoietic stem cell transplant.

Cytogenetics in the management of myeloproliferative neoplasms, mastocytosis and myelodysplastic/myeloproliferative neoplasms: Guidelines from the Group Francophone de Cytogénétique Hématologique (GFCH)

Myeloproliferative neoplasms, mastocytosis, myeloid/lymphoid neoplasms with hypereosinophilia and tyrosine kinase gene fusions, and myelodysplastic/myeloproliferative neoplasms are clonal hematopoietic cancers that, with the exception of certain entities, have an indolent course. In addition to their increasingly important role in the diagnosis of these entities, as shown by the recent classification of hematolymphoid tumors in the 5th edition of the World Health Organization and the International Consensus Classification of myeloid neoplasms and acute leukemias, identification of the profile of acquired genetic abnormalities is essential for adapting patient management and early detection of patients at high risk of progression. Alongside molecular abnormalities, cytogenetic abnormalities play an important role in the diagnosis, prognosis and follow-up of these diseases. Here, we review the recent literature on the impact of chromosomal abnormalities in these different entities and provide updated cytogenetic recommendations and guidelines for their management.

Age and sex associate with outcome in older AML and high risk MDS patients treated with 10-day decitabine

Treatment choice according to the individual conditions remains challenging, particularly in older patients with acute myeloid leukemia (AML) and high risk myelodysplastic syndrome (MDS). The impact of performance status, comorbidities, and physical functioning on survival is not well defined for patients treated with hypomethylating agents. Here we describe the impact of performance status (14% ECOG performance status 2), comorbidity (40% HCT-comorbidity index ≥ 2), and physical functioning (41% short physical performance battery < 9 and 17% ADL index < 6) on overall survival (OS) in 115 older patients (age ≥ 66 years) treated on a clinical trial with a 10-day decitabine schedule. None of the patient-related variables showed a significant association with OS. Multivariable analysis revealed that age > 76 years was significantly associated with reduced OS (HR 1.58; p = 0.043) and female sex was associated with superior OS (HR 0.62; p = 0.06). We further compared the genetic profiles of these subgroups. This revealed comparable mutational profiles in patients younger and older than 76 years, but, interestingly, revealed significantly more prevalent mutated ASXL1, STAG2, and U2AF1 in male compared to female patients. In this cohort of older patients treated with decitabine age and sex, but not comorbidities, physical functioning or cytogenetic risk were associated with overall survival.

Progression in Myeloid Neoplasms: Beyond the Myeloblast

Disease progression in myelodysplastic syndromes (MDS), myelodysplastic-myeloproliferative neoplasms (MDS/MPN), and myeloproliferative neoplasms (MPN), altogether referred to as myeloid neoplasms (MN), is a major source of mortality. Apart from transformation to acute myeloid leukemia, the clinical progression of MN is mostly due to the overgrowth of pre-existing hematopoiesis by the MN without an additional transforming event. Still, MN may evolve along other recurrent yet less well-known scenarios: (1) acquisition of MPN features in MDS or (2) MDS features in MPN, (3) progressive myelofibrosis (MF), (4) acquisition of chronic myelomonocytic leukemia (CMML)-like characteristics in MPN or MDS, (5) development of myeloid sarcoma (MS), (6) lymphoblastic (LB) transformation, (7) histiocytic/dendritic outgrowths. These MN-transformation types exhibit a propensity for extramedullary sites (e.g., skin, lymph nodes, liver), highlighting the importance of lesional biopsies in diagnosis. Gain of distinct mutations/mutational patterns seems to be causative or at least accompanying several of the above-mentioned scenarios. MDS developing MPN features often acquire MPN driver mutations (usually JAK2), and MF. Conversely, MPN gaining MDS features develop, e.g., ASXL1, IDH1/2, SF3B1, and/or SRSF2 mutations. Mutations of RAS-genes are often detected in CMML-like MPN progression. MS ex MN is characterized by complex karyotypes, FLT3 and/or NPM1 mutations, and often monoblastic phenotype. MN with LB transformation is associated with secondary genetic events linked to lineage reprogramming leading to the deregulation of ETV6, IKZF1, PAX5, PU.1, and RUNX1. Finally, the acquisition of MAPK-pathway gene mutations may shape MN toward histiocytic differentiation. Awareness of all these less well-known MN-progression types is important to guide optimal individual patient management.

Genomics of myelodysplastic/myeloproliferative neoplasm

Myelodysplastic/ Myeloproliferative neoplasms (MDS/MPN) demonstrate overlapping pathologic and molecular features of myelodysplastic (MDS) and myeloproliferative (MPN) neoplasms. Diagnosis is difficult based on morphology alone, requiring exclusion of various non-neoplastic causes for CBC abnormalities and morphologic findings and other myeloid neoplasms. Identifying a clonal abnormality by cytogenetics or molecular studies has vastly improved our ability to diagnose MDS/MPN and has been incorporated in the different classification schemas. Currently two separate classification systems are in use- The 5^th edition WHO and international consensus classification. The two competing classifications emphasize genetic work-up and are similar on many levels; however, they do introduce diagnostic dilemma when diagnosing certain entities such as chronic myelomonocytic leukemia in the presence of NPM1 mutations. The genetic profile overlaps among different subentities; however, the combination and the incidence of mutations; together with the clinical features and morphology helps in further subclassification. In this review, we discuss the advances in molecular characterization of MDS/MPN. We attempt to summarize the differences between the various classification schemes, and highlight the changes made in the diagnostic criteria.

Triple-Negative Primary Myelofibrosis: A Bone Marrow Pathology Group Study

Primary myelofibrosis (PMF) is a clonal myeloproliferative neoplasm driven by canonical gene mutations in JAK2, CALR, or MPL in >80% of the cases. PMF that lacks these canonical alterations is termed triple-negative PMF (TN-PMF). The pathologic and genetic characteristics of TN-PMF compared with those of conventional PMF with canonical driver mutations (DM-PMF) have not been well studied. We aimed to identify clinicopathologic and molecular genetic differences between patients with TN-PMF (n = 56) and DM-PMF (n = 89), all of whom fulfilled the 2016 World Health Organization diagnostic criteria for PMF. Compared with the control group, patients in the TN-PMF group were more likely to have thrombocytopenia and less likely to have organomegaly. The bone marrow in patients with TN-PMF showed fewer granulocytic elements and more frequent dyserythropoiesis. Cytogenetic analysis showed a higher incidence of trisomy 8. Targeted next-generation sequencing revealed a lower frequency of ASXL1 mutations but enrichment of ASXL1/SRSF2 comutations. Our findings demonstrated several clinicopathologic and molecular differences between TN-PMF and DM-PMF. These findings, particularly the observed mutation profile characterized by a higher frequency of ASXL1 and SRSF2 comutation, suggest that at least a subset of TN-PMF may be pathogenetically different from DM-PMF, with potential prognostic implications.

The ABNL-MARRO 001 study: a phase 1-2 study of randomly allocated active myeloid target compound combinations in MDS/MPN overlap syndromes

BACKGROUND

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) comprise several rare hematologic malignancies with shared concomitant dysplastic and proliferative clinicopathologic features of bone marrow failure and propensity of acute leukemic transformation, and have significant impact on patient quality of life. The only approved disease-modifying therapies for any of the MDS/MPN are DNA methyltransferase inhibitors (DNMTi) for patients with dysplastic CMML, and still, outcomes are generally poor, making this an important area of unmet clinical need. Due to both the rarity and the heterogeneous nature of MDS/MPN, they have been challenging to study in dedicated prospective studies. Thus, refining first-line treatment strategies has been difficult, and optimal salvage treatments following DNMTi failure have also not been rigorously studied. ABNL-MARRO (A Basket study of Novel therapy for untreated MDS/MPN and Relapsed/Refractory Overlap Syndromes) is an international cooperation that leverages the expertise of the MDS/MPN International Working Group (IWG) and provides the framework for collaborative studies to advance treatment of MDS/MPN and to explore clinical and pathologic markers of disease severity, prognosis, and treatment response.

METHODS

ABNL MARRO 001 (AM-001) is an open label, randomly allocated phase 1/2 study that will test novel treatment combinations in MDS/MPNs, beginning with the novel targeted agent itacitinib, a selective JAK1 inhibitor, combined with ASTX727, a fixed dose oral combination of the DNMTi decitabine and the cytidine deaminase inhibitor cedazuridine to improve decitabine bioavailability.

DISCUSSION

Beyond the primary objectives of the study to evaluate the safety and efficacy of novel treatment combinations in MDS/MPN, the study will (i) Establish the ABNL MARRO infrastructure for future prospective studies, (ii) Forge innovative scientific research that will improve our understanding of pathogenetic mechanisms of disease, and (iii) Inform the clinical application of diagnostic criteria, risk stratification and prognostication tools, as well as response assessments in this heterogeneous patient population.

TRIAL REGISTRATION

This trial was registered with ClinicalTrials.gov on August 19, 2019 (Registration No. NCT04061421).

Myelodysplastic/myeloproliferative neoplasms-unclassifiable with isolated isochromosome 17q represents a distinct clinico-biologic subset: a multi-institutional collaborative study from the Bone Marrow Pathology Group

Classification of myeloid neoplasms with isolated isochromosome i(17q) [17p deletion with inherent monoallelic TP53 loss plus 17q duplication] is controversial. Most cases fall within the WHO unclassifiable myelodysplastic/myeloproliferative neoplasms (MDS/MPN-U) category. The uniformly dismal outcomes warrant better understanding of this entity. We undertook a multi-institutional retrospective study of 92 adult MDS/MPN-U cases from eight institutions. Twenty-nine (32%) patients had isolated i(17q) [MDS/MPN-i(17q)]. Compared to MDS/MPN without i(17q), MDS/MPN-i(17q) patients were significantly younger, had lower platelet and absolute neutrophil counts, and higher frequency of splenomegaly and circulating blasts. MDS/MPN-i(17q) cases showed frequent bilobed neutrophils (75% vs. 23%; P = 0.03), hypolobated megakaryocytes (62% vs. 20%; P = 0.06), and a higher frequency of SETBP1 (69% vs. 5%; P = 0.002) and SRSF2 (63% vs. 5%; P = 0.006) mutations that were frequently co-existent (44% vs. 0%; P = 0.01). TP53 mutations were rare. The mutation profile of MDS/MPN-U-i(17q) was similar to other myeloid neoplasms with i(17q) including atypical chronic myeloid leukemia, chronic myelomonocytic leukemia, myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis, myelodysplastic syndrome and acute myeloid leukemia, with frequent concomitant SETBP1/SRSF2 mutations observed across all the diagnostic entities. Over a median follow-up of 52 months, patients with MDS/MPN-i(17q) showed a shorter median overall survival (11 vs. 28 months; P < 0.001). The presence of i(17q) retained independent poor prognostic value in multivariable Cox-regression analysis [HR 3.686 (1.17-11.6); P = 0.026] along with splenomegaly. We suggest that MDS/MPN-i(17q) warrants recognition as a distinct subtype within the MDS/MPN-U category based on its unique clinico-biologic features and uniformly poor prognosis.

How I manage myeloproliferative neoplasm-unclassifiable: Practical approaches for 2022 and beyond

Myeloproliferative neoplasm (MPN)-unclassifiable (MPN-U) or not otherwise specified represents a rare, poorly defined and heterogeneous group of MPNs. Disease incidence is difficult to define but likely represents close to 5% of all MPNs when strict World Health Organisation (WHO) criteria are applied. Dynamic review over time is required to assess if the disease can be re-classified into another MPN entity. A diagnosis of MPN-U leads to many challenges for both the patient and physician alike including lack of agreed monitoring and therapeutic guidelines, validated prognostic markers and licenced therapies coupled with exclusion from clinical trials. MPN-U has an inherent risk of an aggressive clinical course and transformation in some but who, and when to treat in the chronic phase, including identifying who may require more aggressive therapy at an earlier stage, remains elusive. Moreover, despite the significant thrombotic risk, there is no agreement on systematic primary thromboprophylaxis. We hereby provide a contemporary overview of MPN-U in addition to four illustrative cases providing our collective suggested approaches to clinical challenges.

MDS/MPN-Unclassifiable with t(X;17)(q28;q21) and KANSL1-MTCP1/CMC4 Fusion Gene

Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-U) is a poorly characterized entity among overlap myeloid syndromes. Recent studies have shown heterogeneous mutational profiles in this group being able to subclassify them into entities closely related to the more well-established disorders under the umbrella term of the MDS/MPN group. Recurrent cytogenetic alterations are, nonetheless, rare in MDS/MPN-U. Here, for the first time, we report a case of MDS/MPN-U with a t(X;17)(q28;q21) chromosomal rearrangement leading to the KANSL1-MTCP1 fusion gene.

Hybrid or Mixed Myelodysplastic/Myeloproliferative Disorders - Epidemiological Features and Overview

The WHO-category Myelodysplastic/Myeloproliferative neoplasms (MDS/MPNs) recognizes a unique group of clonal myeloid malignancies exhibiting overlapping features of myelodysplastic as well as myeloproliferative neoplasms. The group consists of chronic myelomonocytic leukemia (CMML), atypical chronic myeloid leukemia, BCR-ABL1-negative (aCML), juvenile myelomonocytic leukemia (JMML), myelodysplastic/myeloproliferative neoplasm with ringed sideroblasts and thrombocytosis (MDS/MPN-RS-T), and myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN-U). The most frequent entity in this category is CMML, while all other diseases are extremely rare. Thus, only very limited data on the epidemiology of these subgroups exists. An appropriate diagnosis and classification can be challenging since the diagnosis is still largely based on morphologic criteria and myelodysplastic as well as myeloproliferative features can be found in various occurrences. The diseases in this category share several features that are common in this specific WHO-category, but also exhibit specific traits for each disease. This review summarizes published data on epidemiological features and offers a brief overview of the main diagnostic criteria and clinical characteristics of the five MDS/MPN subgroups.

A comprehensive genome-wide analysis of long non-coding RNA and mRNA expression profiles of JAK2V617F-positive classical myeloproliferative neoplasms

Aberrant expression of long non-coding RNAs (lncRNAs) is involved in the progression of myeloid neoplasms, but the role of lncRNAs in the JAK2V617F-positive subtype of classical myeloproliferative neoplasms (cMPNs) remains unclear. This study was conducted to clarify the expression and regulation patterns of lncRNAs in JAK2V617F-positive cMPNs, and to explore new potential carcinogenic factors of cMPNs. Bioinformatics analysis of microarray detection and wet testing verification were performed to study the expression and regulation signature of differentially expressed lncRNAs (DELs) and related genes (DEGs) in cMPNs. The expression of lncRNAs and mRNAs were observed to significantly dysregulated in JAK2V617F-positive cMPN patients compared with the normal controls. Co-expression analysis indicated that there were significant differences of the co-expression pattern of lncRNAs and mRNAs in JAK2V617F-positive cMPN patients compared to normal controls. GO and KEGG pathway analysis of DEGs and DELs showed the involvement of several pathways previously reported to regulate the pathogenesis of leukemia and cMPNs. Cis- and trans-regulation analysis of lncRNAs showed that ZNF141, DHX29, NOC2L, MAS1L, AFAP1L1, and CPN2 were significantly cis-regulated by lncRNA ENST00000356347, ENST00000456816, hsa-mir-449c, NR_026874, TCONS_00012136, uc003lqp.2, and ENST00000456816, respectively, and DELs were mostly correlated with transcription factors including CTBP2, SUZ12, REST, STAT2, and GATA4 to jointly regulate multiple target genes. In summary, expression profiles of lncRNAs and mRNAs were significantly altered in JAK2V617F-positive cMPNs, the relative signaling pathway, co-expression, cis- and trans-regulation were regulated by dysregulation of lncRNAs and several important genes, such as ITGB3, which may act as a promising carcinogenic factor, warrant further investigation.

Canonical Wnt: a safeguard and threat for erythropoiesis

Myeloid dysplastic syndrome (MDS) reflects a preleukemic bone marrow (BM) disorder with limited treatment options and poor disease survival. As only a minority of MDS patients are eligible for curative hematopoietic stem cell transplantation, there is an urgent need to develop alternative treatment options. Chronic activation of Wnt/β-catenin has been implicated to underlie MDS formation and recently assigned to drive MDS transformation to acute myeloid leukemia. Wnt/β-catenin signaling therefore may harbor a pharmaceutical target to treat MDS and/or prevent leukemia formation. However, targeting the Wnt/β-catenin pathway will also affect healthy hematopoiesis in MDS patients. The control of Wnt/β-catenin in healthy hematopoiesis is poorly understood. Whereas Wnt/β-catenin is dispensable for steady-state erythropoiesis, its activity is essential for stress erythropoiesis in response to BM injury and anemia. Manipulation of Wnt/β-catenin signaling in MDS may therefore deregulate stress erythropoiesis and even increase anemia severity. Here, we provide a comprehensive overview of the most recent and established insights in the field to acquire more insight into the control of Wnt/β-catenin signaling in healthy and inefficient erythropoiesis as seen in MDS.

Pathogenic Mutations and Atypical Flow Cytometric Findings Characterize the Majority of Unclassifiable Myelodysplastic/Myeloproliferative Neoplasms

OBJECTIVES

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are a group of rare and heterogeneous hematopoietic disorders that frequently present a diagnostic challenge. Here we present our institutional experience with next-generation sequencing (NGS), together with morphologic, flow cytometric, and cytogenetic evaluation, in the diagnosis of MDS/MPN, with particular emphasis on MDS/MPN unclassifiable (MPN-U).

METHODS

We evaluated the morphologic, flow cytometric, cytogenetic, and molecular characteristics of all MDS/MPN cases that underwent NGS at our institution between April 2016 and February 2019.

RESULTS

Thirty-seven cases of MDS/MPN were identified, including 14 cases of MDS/MPN-U. Ninety-seven percent harbored mutations and immunophenotypic aberrancies (36/37), while only 38% had cytogenetic abnormalities (12/32). The MDS/MPN-U group had the highest rate of myeloblast phenotypic abnormalities and had a high mutation rate of approximately 2.7 mutated genes per case, most commonly in JAK2, SRSF2, and ASXL1.

CONCLUSIONS

No single ancillary study was abnormal in every case, but all cases had at least one abnormal finding, demonstrating the usefulness of a multiparameter approach to the diagnosis of MDS/MPN. Although a few specific mutations were found exclusively in MDS/MPN-U and JAK2 mutations were most prevalent, larger studies are needed to determine whether MDS/MPN-U has a mutational "fingerprint," which may aid in diagnosis and targeted therapy.

Examining disease boundaries: Genetics of myelodysplastic/myeloproliferative neoplasms

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are clonal myeloid malignancies that are characterized by dysplasia resulting in cytopenias as well as proliferative features such as thrombocytosis or splenomegaly. Recent studies have better defined the genetics underlying this diverse group of disorders. Trisomy 8, monosomy 7, and loss of Y chromosome are the most common cytogenetic abnormalities seen. Chronic myelomonocytic leukemia (CMML) likely develops from early clones with TET2 mutations that drive granulomonocytic differentiation. Mutations in SRSF2 are common and those in the RAS-MAPK pathway are typically implicated in disease with a proliferative phenotype. Several prognostic systems have incorporated genetic features, with ASXL1 most consistently demonstrating worse prognosis. Atypical chronic myeloid leukemia (aCML) is most known for granulocytosis with marked dysplasia and often harbors ASXL1 mutations, but SETBP1 and ETNK1 are more specific to this disease. MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) most commonly involves spliceosome mutations (namely SF3B1) and mutations in the JAK-STAT pathway. Finally, MDS/MPN-unclassifiable (MDS/MPN-U) is least characterized but a significant fraction carries mutations in TP53. The remaining patients have clinical and/or genetic features similar to the other MDS/MPNs, suggesting there is room to better characterize this entity. Evolution from age-related clonal hematopoiesis to MDS/MPN likely depends on the order of mutation acquisition and interactions between various biologic factors. Genetics will continue to play a critical role in our understanding of these illnesses and advancing patient care.

Molecular landscape and clonal architecture of adult myelodysplastic/myeloproliferative neoplasms

More than 90% of patients with myelodysplastic/myeloproliferative neoplasms (MDSs/MPNs) harbor somatic mutations in myeloid-related genes, but still, current diagnostic criteria do not include molecular data. We performed genome-wide sequencing techniques to characterize the mutational landscape of a large and clinically well-characterized cohort including 367 adults with MDS/MPN subtypes, including chronic myelomonocytic leukemia (CMML; n = 119), atypical chronic myeloid leukemia (aCML; n = 71), MDS/MPN with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T; n = 71), and MDS/MPN unclassifiable (MDS/MPN-U; n = 106). A total of 30 genes were recurrently mutated in ≥3% of the cohort. Distribution of recurrently mutated genes and clonal architecture differed among MDS/MPN subtypes. Statistical analysis revealed significant correlations between recurrently mutated genes, as well as genotype-phenotype associations. We identified specific gene combinations that were associated with distinct MDS/MPN subtypes and that were mutually exclusive with most of the other MDSs/MPNs (eg, TET2-SRSF2 in CMML, ASXL1-SETBP1 in aCML, and SF3B1-JAK2 in MDS/MPN-RS-T). Patients with MDS/MPN-U were the most heterogeneous and displayed different molecular profiles that mimicked the ones observed in other MDS/MPN subtypes and that had an impact on the outcome of the patients. Specific gene mutations also had an impact on the outcome of the different MDS/MPN subtypes, which may be relevant for clinical decision-making. Overall, the results of this study help to elucidate the heterogeneity found in these neoplasms, which can be of use in the clinical setting of MDS/MPN.

Gender-related differences in the outcomes and genomic landscape of patients with myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes

Myelodysplastic syndrome/myeloproliferative neoplasm (MDS/MPN) overlap syndromes show a male predominance and men with MDS/MPN have worse outcomes, but it is unknown if the mutational burden differs between genders. We reviewed 167 patients with MDS/MPN and found that men had worse overall survival [hazard ratio (HR) 2·09, 95% confidence interval (CI) 1·16-3·75; P = 0·013] independent of subtype, Revised International Prognostic Scoring System score and age at diagnosis. We analysed the genomic data of a subset of 100 patients. Men had 0·88 more somatic mutations on average (95% CI 0·20-1·56, P = 0·011) independent of subtype, sample source and blast percentage. More somatic mutations was associated with a higher incidence of transformation to acute myeloid leukaemia (subdistribution HR 1·30, 95% CI 1·01-1·70; P = 0·046). Men had 0·70 more mutations in high-risk genes [additional sex combs like-1 (ASXL1), enhancer of zeste homolog 2 (EZH2), Runt-related transcription factor 1 (RUNX1), SET binding protein 1 (SETBP1), NRAS proto-oncogene, GTPase (NRAS), stromal antigen 2 (STAG2)] on average (95% CI 0·11-1·29, P = 0·021), and 13-times higher odds of harbouring an EZH2 mutation (95% CI 1·64-102·94, P = 0·015). The presence of an EZH2 mutation was associated with worse survival among men (HR 2·98, 95% CI 1·1-8·0; P = 0·031). Our present findings suggest that the worse outcomes in men with MDS/MPN are associated with a higher number of somatic mutations, especially in high-risk genes. These results warrant validation in larger cohorts and investigation of the underlying mechanisms.

Development of a myelodysplastic/myeloproliferative neoplasm-unclassifiable in a patient with acute myeloid leukemia: a case report and literature review

Myelodysplastic/myeloproliferative neoplasms (MDS/MPNs) are a heterogeneous group of hematologic malignancies characterized by dysplastic and myeloproliferative overlapping features in the bone marrow and blood. The occurrence of the disease is related to age, prior history of MPN or MDS, and recent cytotoxic or growth factor therapy, but it rarely develops after acute myeloid leukemia (AML). We report a rare case of a patient diagnosed with AML with t(8; 21)(q22; q22) who received systematic chemotherapy. After 4 years of follow-up, MDS/MPN-unclassifiable occurred without signs of primary AML recurrence.

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.

Genetic Aspects of Myelodysplastic/Myeloproliferative Neoplasms

Simple Summary

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

Abstract

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

Sex-Related Differences in Chronic Myeloid Neoplasms: From the Clinical Observation to the Underlying Biology

Chronic myeloid neoplasms are clonal diseases with variable clinical course and outcomes and despite the introduction of novel therapies, patients with high-risk disease continue to have overall poor outcomes. Different groups have highlighted that men have overall worse survival and higher incidence of transformation to acute leukemia compared to women across neoplasms such as myelodysplastic syndrome (MDS), myeloproliferative neoplasms (MPN), MDS/MPN overlap neoplasms, and CML. More recent studies evaluating the genomic profile of patients with these neoplasms demonstrated a male predominance for mutations in high-risk genes including ASXL1, U2AF1, SRSF2 and ZRSR2. The understanding of the underlying biology is limited but a number of hypotheses have been developed and are currently being investigated. This review summarizes the current knowledge about sex-related differences in the clinical outcomes and genomic profile of patients with chronic myeloid neoplasms and discusses the hypothesized biologic mechanisms as an attempt to explain these observations.

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.

Navigating Myelodysplastic and Myelodysplastic/Myeloproliferative Overlap Syndromes

Myelodysplastic syndromes (MDS) and MDS/myeloproliferative neoplasms (MPNs) are clonal diseases that differ in morphologic diagnostic criteria but share some common disease phenotypes that include cytopenias, propensity to acute myeloid leukemia evolution, and a substantially shortened patient survival. MDS/MPNs share many clinical and molecular features with MDS, including frequent mutations involving epigenetic modifier and/or spliceosome genes. Although the current 2016 World Health Organization classification incorporates some genetic features in its diagnostic criteria for MDS and MDS/MPNs, recent accumulation of data has underscored the importance of the mutation profiles on both disease classification and prognosis. Machine-learning algorithms have identified distinct molecular genetic signatures that help refine prognosis and notable associations of these genetic signatures with morphologic and clinical features. Combined geno-clinical models that incorporate mutation data seem to surpass the current prognostic schemes. Future MDS classification and prognostication schema will be based on the portfolio of genetic aberrations and traditional features, such as blast count and clinical factors. Arriving at these systems will require studies on large patient cohorts that incorporate advanced computational analysis. The current treatment algorithm in MDS is based on patient risk as derived from existing prognostic and disease classes. Luspatercept is newly approved for patients with MDS and ring sideroblasts who are transfusion dependent after erythropoietic-stimulating agent failure. Other agents that address red blood cell transfusion dependence in patients with lower-risk MDS and the failure of hypomethylating agents in higher-risk disease are in advanced testing. Finally, a plethora of novel targeted agents and immune checkpoint inhibitors are being evaluated in combination with a hypomethylating agent backbone to augment the depth and duration of response and, we hope, improve overall survival.

Favorable outcome of a patient with an unclassifiable myelodysplastic syndrome/myeloproliferative neoplasm treated with allogeneic hematopoietic stem cell transplantation

The entity myelodysplastic syndrome/myeloproliferative neoplasm overlap syndrome is characterized by the coexistence of both myeloproliferative and myelodysplastic features in the bone marrow. Risk assessment and treatment recommendations have not been standardized, and clinicians rely on updated patient studies and reviews to make decisions for treatment approaches. Histopathological features have traditionally been important, although in the last decade, several studies have reported mutational profiles of this rare disease. Here, we present a case, wherein the patient presented with leukocytosis and the diagnostic work-up revealed features of myelodysplastic syndrome/myeloproliferative neoplasm overlap syndrome. Mutational profiling revealed mutations in four genes associated with myeloid malignancies, namely, EZH2, CUX1, TET2, and BCOR. After initial therapy with hydroxyurea and interferon-α, the patient underwent allogeneic hematopoietic stem cell transplantation, with reduced intensity conditioning and a matched sibling donor. He had no signs of relapsed disease 2 years after the transplant. Based on the patient outcome, we summarize the diagnostic and therapeutic approaches for patients diagnosed with myelodysplastic syndrome/myeloproliferative neoplasm overlap syndrome, and review the current literature, emphasizing the role of genetic mutations and allogeneic hematopoietic stem cell transplantation. Larger and more detailed clinical studies are strongly needed to optimize and standardize diagnostic and therapeutic approaches for this disease.

Genomics of myelodysplastic syndrome/myeloproliferative neoplasm overlap syndromes

Myelodysplastic syndrome (MDS)/myeloproliferative neoplasm (MPN) overlap syndromes are uniquely classified neoplasms occurring in both children and adults. This category consists of 5 neoplastic subtypes: chronic myelomonocytic leukemia (CMML), juvenile myelomonocytic leukemia (JMML), BCR-ABL1-negative atypical chronic myeloid leukemia (aCML), MDS/MPN-ring sideroblasts and thrombocytosis (MDS/MPN-RS-T), and MDS/MPN-unclassifiable (U). Cytogenetic abnormalities and somatic copy number variations are uncommon; however, >90% patients harbor gene mutations. Although no single gene mutation is specific to a disease subtype, certain mutational signatures in the context of appropriate clinical and morphological features can be used to establish a diagnosis. In CMML, mutated coexpression of TET2 and SRSF2 results in clonal hematopoiesis skewed toward monocytosis, and the ensuing acquisition of driver mutations including ASXL1, NRAS, and CBL results in overt disease. MDS/MPN-RS-T demonstrates features of SF3B1-mutant MDS with ring sideroblasts (MDS-RS), with the development of thrombocytosis secondary to the acquisition of signaling mutations, most commonly JAK2V617F. JMML, the only pediatric entity, is a bona fide RASopathy, with germline and somatic mutations occurring in the oncogenic RAS pathway giving rise to disease. BCR-ABL1-negative aCML is characterized by dysplastic neutrophilia and is enriched in SETBP1 and ETNK1 mutations, whereas MDS/MPN-U is the least defined and lacks a characteristic mutational signature. Molecular profiling also provides prognostic information, with truncating ASXL1 mutations being universally detrimental and germline CBL mutations in JMML showing spontaneous regression. Sequencing information in certain cases can help identify potential targeted therapies (IDH1, IDH2, and splicing mutations) and should be a mainstay in the diagnosis and management of these neoplasms.

Efficacy of ruxolitinib in a patient with myelodysplastic/myeloproliferative neoplasm unclassifiable and co-mutated JAK2, SF3B1 and TP53

Myelodysplastic/myeloproliferative neoplasm, unclassifiable (MDS/MPN-U) is a rare but heterogeneous subtype of MDS/MPN, with no specific genetic alterations and standard treatments. ASXL1, SRSF2, TET2, JAK2 and NRAS are commonly mutated in MDS/MPN-U. Double gene mutations could be detected in MDS/MPN-U, however, co-mutations of 3 and more genes in this disease entity are very rare. Here, we present a case of MDS/MPN-U with triple mutations involving JAK2, SF3B1, and TP53. After failure of traditional therapy including hydroxyurea and interferon-α, the patient received ruxolitinib monotherapy and achieved hematological response quickly. Though mutations in TP53 implied a poor prognosis in myeloid malignancies, this patient has maintained no AML transformation for 26 months since diagnosis. Further research on complex mutations in the pathogenesis and prognosis of MDS/MPN-U is warranted.

Progression, transformation, and unusual manifestations of myelodysplastic syndromes and myelodysplastic-myeloproliferative neoplasms: lessons learned from the XIV European Bone Marrow Working Group Course 2019

Disease progression in myelodysplastic syndromes (MDS) and myelodysplastic-myeloproliferative neoplasms (MDS/MPN) is a major source of mortality. The European Bone Marrow Working Group organized a dedicated workshop to address MDS and MDS/MPN progression, and myeloid neoplasms with histiocytic and lymphoblastic outgrowths in 2019 in Frankfurt, Germany. In this report, we summarize clinical, histopathological, and molecular features of 28 cases. Most cases illustrate that prognostic mutational profiles change during follow-up due to accumulation of high-risk mutations in the trunk clone, and that results from repeated molecular testing can often explain the clinical progression, suggesting that regular genetic testing may predict transformation by early detection of aggressive clones. Importantly, identical mutations can be linked to different clinical behaviors or risks of fibrotic progression and/or transformation in a context-dependent manner, i.e., MDS or MDS/MPN. Moreover, the order of mutational acquisition and the involved cell lineages matter. Several cases exemplify that histiocytic outgrowths in myeloid neoplasms are usually accompanied by a more aggressive clinical course and may be considered harbinger of disease progression. Exceptionally, lymphoblastic transformations can be seen. As best estimable, the histiocytic and lymphoblastic compounds in all occasions were clonally related to the myeloid compound and-where studied-displayed genomic alterations of, e.g., transcription factor genes or genes involved in MAPK signaling that might be mechanistically linked to the respective type of non-myeloid outgrowth.

Outcome of Allogeneic Hematopoietic Stem Cell Transplantation in Patients with Myelodysplastic/Myeloproliferative Neoplasms-Unclassifiable: A Retrospective Nationwide Study of the Japan Society for Hematopoietic Cell Transplantation

To date, there are no data focusing on outcomes of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with myelodysplastic/myeloproliferative neoplasms, unclassifiable (MDS/MPN-U). This study aimed to evaluate outcomes and prognostic factors in patients with MDS/MPN-U after allo-HSCT using Japanese nationwide registry data. The primary endpoint was 3-year overall survival (OS); secondary endpoints included the cumulative incidence of relapse and nonrelapse mortality (NRM). We evaluated the prognostic factors for 3-year OS by univariate analysis using the log-rank test. In our cohort of 86 patients with MDS/MPN-U, we found a 3-year OS of 48.5%, cumulative incidence of relapse of 23.7%, and NRM of 26.3%. The 3-year OS was significantly worse in patients age ≥50 years compared with those age <50 years (38.1% versus 65.0%; P = .049) and in patients with disease progression compared with those without disease progression (28.4% versus 57.2%; P = .042). Our results suggest that allo-HSCT may offer a curative option for patients with MDS/MPN-U, and that age and disease status could be important indicators in helping clinicians determine treatment options for these patients.

Neoantigens in Hematologic Malignancies

T cell cancer neoantigens are created from peptides derived from cancer-specific aberrant proteins, such as mutated and fusion proteins, presented in complex with human leukocyte antigens on the cancer cell surface. Because expression of the aberrant target protein is exclusive to malignant cells, immunotherapy directed against neoantigens should avoid “on-target, off-tumor” toxicity. The efficacy of neoantigen vaccines in melanoma and glioblastoma and of adoptive transfer of neoantigen-specific T cells in epithelial tumors indicates that neoantigens are valid therapeutic targets. Improvements in sequencing technology and innovations in antigen discovery approaches have facilitated the identification of neoantigens. In comparison to many solid tumors, hematologic malignancies have few mutations and thus fewer potential neoantigens. Despite this, neoantigens have been identified in a wide variety of hematologic malignancies. These include mutated nucleophosmin1 and PML-RARA in acute myeloid leukemia, ETV6-RUNX1 fusions and other mutated proteins in acute lymphoblastic leukemia, BCR-ABL1 fusions in chronic myeloid leukemia, driver mutations in myeloproliferative neoplasms, immunoglobulins in lymphomas, and proteins derived from patient-specific mutations in chronic lymphoid leukemias. We will review advances in the field of neoantigen discovery, describe the spectrum of identified neoantigens in hematologic malignancies, and discuss the potential of these neoantigens for clinical translation.

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

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

Defining the Boundary Between Myelodysplastic Syndromes and Myeloproliferative Neoplasms

In this article we provide a practical and comprehensive review of myeloid neoplasms with overlapping myelodysplastic (MDS) and myeloproliferative (MPN) features, with emphasis on recent updates in classification, particularly the utility of morphologic, cytogenetic, and molecular findings in better defining and classifying these disease entities. We provide the reader with a summary of the most recent developments and updates that have helped further our understanding of the genomic landscape, clinicopathologic features, and prognostic elements of myeloid neoplasms with MDS/MPN features.

Challenges in Myelodysplastic/Myeloproliferative Neoplasms (MDS/MPN)

Myelodysplastic/myeloproliferative neoplasms (MDS/MPN) are hybrid group of chronic myeloid neoplasms combining features of both MDS and MPN. The World Health Organization classification coined this group designation in 2008 to include chronic myelomonocytic leukemia, atypical chronic myeloid leukemia, juvenile myelomoncoytic leukemia, refractory anemia with ring sideroblasts and thrombocytosis as a provisional entity, and MDS/MPN unclassified. In this review, we highlight the challenges in diagnosing this group of the diseases, summarize the updates in classification, and discuss recent evolving understanding of the genetic landscape. We review risk-stratification models and overview the current management largely adapted from current MDS or MPN therapies. We define clinical benefit of therapy based on new proposed response criteria developed specifically for these groups of neoplasms. Finally, we introduce future opportunities including the planned international ABN MARRO (A Novel therapy combinations in untreated MDS/MPN And Relapsed/Refractory Overlap Syndromes) clinical study led by the MDS/MPN International Working Group.