Genomic patterns associated with hypoplastic compared to hyperplastic myelodysplastic syndromes

Comparison of the 2022 world health organization classification and international consensus classification in myelodysplastic syndromes/neoplasms

In 2022, two novel classification systems for myelodysplastic syndromes/neoplasms (MDS) have been proposed: the International Consensus Classification (ICC) and the 2022 World Health Organization (WHO-2022) classification. These two contemporary systems exhibit numerous shared features but also diverge significantly in terminology and the definition of new entities. Thus, we retrospectively validated the ICC and WHO-2022 classification and found that both systems promoted efficient segregation of this heterogeneous disease. After examining the distinction between the two systems, we showed that a peripheral blood blast percentage ≥ 5% indicates adverse survival. Identifying MDS/acute myeloid leukemia with MDS-related gene mutations or cytogenetic abnormalities helps differentiate survival outcomes. In MDS, not otherwise specified patients, those diagnosed with hypoplastic MDS and single lineage dysplasia displayed a trend of superior survival compared to other low-risk MDS patients. Furthermore, the impact of bone marrow fibrosis on survival was less pronounced within the ICC framework. Allogeneic transplantation appears to improve outcomes for patients diagnosed with MDS with excess blasts in the ICC. Therefore, we proposed an integrated system that may lead to the accurate diagnosis and advancement of future research for MDS. Prospective studies are warranted to validate this refined classification.

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.

Comparison of the International Consensus and 5th WHO edition classifications of adult myelodysplastic syndromes and acute myeloid leukemia

Several editions of the World Health Organization (WHO) classifications of lympho-hemopoietic neoplasms in 2001, 2008, and 2016 served as the international standard for diagnosis. Since the 4th WHO edition, here referred as WHO-HAEM4, significant clinico-pathological, immunophenotypic, and molecular advances have been made in the field of myeloid neoplasms, which have contributed to refine diagnostic criteria, to upgrade entities previously defined as provisional and to identify new entities. This process has resulted in two recent classification proposals of myeloid neoplasms: the International Consensus Classification (ICC) and the 5th edition of the WHO classification (WHO-HAEM5). In this paper, we review and compare the two classifications in terms of diagnostic criteria and entity definition, with a focus on adult myelodysplastic syndromes/neoplasms (MDS) and acute myeloid leukemia (AML). The goal is to provide a tool to facilitate the work of pathologists, hematologists and researchers involved in the diagnosis and treatment of these hematological malignancies.

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.

Clonality in immune aplastic anemia: Mechanisms of immune escape or malignant transformation

Aplastic anemia (AA) is the prototypic bone marrow failure syndrome and can be classified as either acquired or inherited. Inherited forms are due to the effects of germline mutations, while acquired AA is suspected to result from cytotoxic T-cell mediated immune attack on hematopoietic stem and progenitor cells. Once thought to be a purely "benign" condition, clonality in the form of chromosomal abnormalities and single nucleotide variants is now well recognized in AA. Mechanisms underpinning this clonality likely relate to selection of clones that allow immune evasion or increased cell survival the marrow environment under immune attack. Widespread use and availability of next generation and other genetic sequencing techniques has enabled us to better understand the genomic landscape of aplastic anemia. This review focuses on the current concepts associated with clonality, in particular somatic mutations and their impact on diagnosis and clinical outcomes in immune aplastic anemia.

The 5th edition of the World Health Organization Classification of Haematolymphoid Tumours: Myeloid and Histiocytic/Dendritic Neoplasms

The upcoming 5th edition of the World Health Organization (WHO) Classification of Haematolymphoid Tumours is part of an effort to hierarchically catalogue human cancers arising in various organ systems within a single relational database. This paper summarizes the new WHO classification scheme for myeloid and histiocytic/dendritic neoplasms and provides an overview of the principles and rationale underpinning changes from the prior edition. The definition and diagnosis of disease types continues to be based on multiple clinicopathologic parameters, but with refinement of diagnostic criteria and emphasis on therapeutically and/or prognostically actionable biomarkers. While a genetic basis for defining diseases is sought where possible, the classification strives to keep practical worldwide applicability in perspective. The result is an enhanced, contemporary, evidence-based classification of myeloid and histiocytic/dendritic neoplasms, rooted in molecular biology and an organizational structure that permits future scalability as new discoveries continue to inexorably inform future editions.

Hypoplastic myelodysplastic syndrome and acquired aplastic anemia: Immune‑mediated bone marrow failure syndromes (Review)

Hypoplastic myelodysplastic syndrome (hMDS) and aplastic anemia (AA) are rare hematopoietic disorders characterized by pancytopenia with hypoplastic bone marrow (BM). hMDS and idiopathic AA share overlapping clinicopathological features, making a diagnosis very difficult. The differential diagnosis is mainly based on the presence of dysgranulopoiesis, dysmegakaryocytopoiesis, an increased percentage of blasts, and abnormal karyotype, all favouring the diagnosis of hMDS. An accurate diagnosis has important clinical implications, as the prognosis and treatment can be quite different for these diseases. Patients with hMDS have a greater risk of neoplastic progression, a shorter survival time and a lower response to immunosuppressive therapy compared with patients with AA. There is compelling evidence that these distinct clinical entities share a common pathophysiology based on the damage of hematopoietic stem and progenitor cells (HSPCs) by cytotoxic T cells. Expanded T cells overproduce proinflammatory cytokines (interferon-γ and tumor necrosis factor-α), resulting in decreased proliferation and increased apoptosis of HSPCs. The antigens that trigger this abnormal immune response are not known, but potential candidates have been suggested, including Wilms tumor protein 1 and human leukocyte antigen class I molecules. Our understanding of the molecular pathogenesis of these BM failure syndromes has been improved by next-generation sequencing, which has enabled the identification of a large spectrum of mutations. It has also brought new challenges, such as the interpretation of variants of uncertain significance and clonal hematopoiesis of indeterminate potential. The present review discusses the main clinicopathological differences between hMDS and acquired AA, focuses on the molecular background and highlights the importance of molecular testing.

The clinical and laboratory evaluation of patients with suspected hypocellular marrow failure

The overlap in clinical presentation and bone marrow features of acquired and inherited causes of hypocellular marrow failure poses a significant diagnostic challenge in real case scenarios, particularly in nonsevere disease. The distinction between acquired aplastic anemia (aAA), hypocellular myelodysplastic syndrome (MDS), and inherited bone marrow failure syndromes presenting with marrow hypocellularity is critical to inform appropriate care. Here, we review the workup of hypocellular marrow failure in adolescents through adults. Given the limitations of relying on clinical stigmata or family history to identify patients with inherited etiologies, we outline a diagnostic approach incorporating comprehensive genetic testing in patients with hypocellular marrow failure that does not require immediate therapy and thus allows time to complete the evaluation. We also review the clinical utility of marrow array to detect acquired 6p copy number-neutral loss of heterozygosity to support a diagnosis of aAA, the complexities of telomere length testing in patients with aAA, short telomere syndromes, and other inherited bone marrow failure syndromes, as well as the limitations of somatic mutation testing for mutations in myeloid malignancy genes for discriminating between the various diagnostic possibilities.

Biology and clinical management of hypoplastic MDS: MDS as a bone marrow failure syndrome

Hypoplastic MDS is a subset of MDS characterized by marrow hypocellularity diagnosed in 10-15% of MDS patients. The pathogenesis of this disease shares features of aplastic anemia with activation of the effector T cells against hematopoietic stem and progenitor cells and high-risk MDS with acquisition of somatic mutations that provide survival and growth advantage of these cells in the inflammatory bone marrow microenvironment. Clonal evolution in hypoplastic MDS may be associated with accumulation of DNA damage and progression to AML while clonal hematopoiesis in aplastic anemia is strongly related to immune escape of the hematopoietic cells. Distinction of hypoplastic MDS from other acquired and inherited bone marrow failure syndromes is frequently challenging but it is critical for the appropriate clinical management of the patients. Treatment with immunosuppression is an important component of the clinical approach to patients with hypoplastic MDS while hypomethylating agents and early allogeneic bone marrow transplantation are also considerations in some patients. In this review, we summarize the current literature on the biology of hypoplastic MDS, the differences between this disease and other bone marrow failure syndromes, and the treatment algorithm for patients with this subtype of MDS.

Hypoplastic Myelodysplastic Syndromes: Just an Overlap Syndrome?

Simple Summary

Hypoplastic myelodysplastic syndromes (hMDS) represent a diagnostic conundrum. They share morphologic and clinical features of both MDS (dysplasia, genetic lesions and cytopenias) and aplastic anemia (AA; i.e., hypocellularity and autoimmunity) and are not comprised in the last WHO classification. In this review we recapitulate the main clinical, pathogenic and therapeutic aspects of hypo-MDS and discuss why they deserve to be distinguished from normo/hypercellular MDS and AA. We conclude that hMDS may present in two phenotypes: one more proinflammatory and autoimmune, more similar to AA, responding to immunosuppression; and one MDS-like dominated by genetic lesions, suppression of immune surveillance, and tumor escape, more prone to leukemic evolution.

Abstract

Myelodysplasias with hypocellular bone marrow (hMDS) represent about 10–15% of MDS and are defined by reduced bone marrow cellularity (i.e., <25% or an inappropriately reduced cellularity for their age in young patients). Their diagnosis is still an object of debate and has not been clearly established in the recent WHO classification. Clinical and morphological overlaps with both normo/hypercellular MDS and aplastic anemia include cytopenias, the presence of marrow hypocellularity and dysplasia, and cytogenetic and molecular alterations. Activation of the immune system against the hematopoietic precursors, typical of aplastic anemia, is reckoned even in hMDS and may account for the response to immunosuppressive treatment. Finally, the hMDS outcome seems more favorable than that of normo/hypercellular MDS patients. In this review, we analyze the available literature on hMDS, focusing on clinical, immunological, and molecular features. We show that hMDS pathogenesis and clinical presentation are peculiar, albeit in-between aplastic anemia (AA) and normo/hypercellular MDS. Two different hMDS phenotypes may be encountered: one featured by inflammation and immune activation, with increased cytotoxic T cells, increased T and B regulatory cells, and better response to immunosuppression; and the other, resembling MDS, where T and B regulatory/suppressor cells prevail, leading to genetic clonal selection and an increased risk of leukemic evolution. The identification of the prevailing hMDS phenotype might assist treatment choice, inform prognosis, and suggest personalized monitoring.

Eltrombopag monotherapy can improve hematopoiesis in patients with low to intermediate risk-1 myelodysplastic syndrome

Myelodysplastic syndromes (MDS) are a group of clonal myeloid disorders characterized by low blood counts and a propensity to develop acute myeloid leukemia. The management of lowerrisk (LR) MDS with persistent cytopenias remains suboptimal. Eltrombopag, a thrombopoietin-receptor agonist, can improve platelet counts in LR-MDS and trilineage hematopoiesis in aplastic anemia. We conducted a phase II dose modification study to investigate the safety and efficacy of eltrombopag in LR-MDS. The eltrombopag dose was escalated from 50 mg/day to a maximum of 150 mg/day over a period of 16 weeks. The primary efficacy endpoint was hematologic response at 16-20 weeks. Eleven of 25 (44%) patients responded; five and six patients had uni- or bi-lineage hematologic responses, respectively. The predictors of response were presence of a paroxysmal nocturnal hemoglobinuria clone, marrow hypocellularity, thrombocytopenia, and elevated plasma thrombopoietin levels at study entry. The safety profile was consistent with that found in previous eltrombopag studies in aplastic anemia; no patients discontinued the drug due to adverse events. Three patients developed reversible grade 3 liver toxicity and one patient had increased reticulin fibrosis. Ten patients discontinued eltrombopag after achieving a robust response (median time 16 months); four of them reinitiated eltrombopag because of declining blood counts, and all attained a second robust response. Six patients had disease progression not associated with expansion of mutated clones and no patient progressed to develop acute myeloid leukemia on study. In conclusion, eltrombopag was well-tolerated and effective in restoring hematopoiesis in some patients with low or intermediate-1 risk MDS. This study was registered at clinicaltrials.gov as #NCT00932156.

Outcome of allogeneic hematopoietic stem cell transplantation for hypoplastic myelodysplastic syndrome

The prognosis of patients with hypoplastic myelodysplastic syndrome (hMDS) after receiving allogeneic hematopoietic stem cell transplantation (allo-HSCT) remains unclear. This study aimed to evaluate the outcomes of patients with hMDS after allo-HSCT. Between September 2013 and October 2019, a total of 20 consecutive patients with hMDS and 1 patient with clonal cytopenia of undermined significance (CCUS) who underwent allo-HSCT, which included procedures with 9 matched sibling donors, 2 matched unrelated donors, 4 mismatched unrelated donors and 6 haploidentical donors, were enrolled in this study. The median time for myeloid engraftment was 11 days (range 9-17 days), and that for platelet engraftment was 10 days (range 7-17 days). The cumulative incidence (CI) of myeloid and platelet recovery was 95.2 ± 6.0% and 90.5 ± 7.3%, respectively. The CI rates were 40.0 ± 11.3% for grades II-III acute graft-versus-host disease (GVHD), 36.8 ± 11.5% for chronic GVHD and 23.8 ± 9.6% for nonrelapse mortality. No patients experienced relapse. Sixteen surviving patients were followed up for a median of 1113 days (range 110-2305 days), and the overall survival and relapse-free survival rates were both 72.7 ± 10.6%. This limited retrospective analysis suggests that patients with hMDS had a favorable survival after allo-HSCT.

Cui bono? Finding the value of allogeneic stem cell transplantation for lower-risk myelodysplastic syndromes

Introduction: The myelodysplastic syndromes (MDS) vary in their risk of disease progression; progression includes increasingly severe bone marrow failure, reclassification as acute myeloid leukemia (AML), and death. Prognostic tools guide recommendations for allogeneic stem cell transplantation (alloSCT), the only curative option. AlloSCT is typically reserved for patients with higher-risk MDS as defined by existing prognostic tools, although additional clinical and biological factors in lower-risk patients may influence this dogma.Areas covered: This review discusses the current understanding of MDS risk stratification as it pertains to the use of alloSCT in subpopulations of MDS patients with a particular focus on the use of alloSCT in patients with lower-risk disease.Expert commentary: Though high-quality data are lacking, some lower-risk MDS patients may benefit from alloSCT, which offers the only prospect of cure. Understanding the etiologic role and prognostic impact of recurring genetic events may improve existing risk stratification and become integral facets of prognostic schemata. The identification of additional factors influencing the prognoses of patients currently lumped together as 'lower-risk' will likewise improve the selection of MDS patients for early intervention or aggressive therapies such as alloSCT.

Distinctive and common features of moderate aplastic anaemia

The therapy algorithm for severe aplastic anaemia (sAA) is established but moderate AA (mAA), which likely reflects a more diverse pathogenic mechanism, often represents a treatment/management conundrum. A cohort of AA patients (n = 325) was queried for those with non‐severe disease using stringent criteria including bone marrow hypocellularity and chronic persistence of moderately depressed blood counts. As a result, we have identified and analyzed pathological and clinical features in 85 mAA patients. Progression to sAA and direct clonal evolution (paroxysmal nocturnal haemoglobinuria/acute myeloid leukaemia; PNH/AML) occurred in 16%, 11% and 1% of mAA cases respectively. Of the mAA patients who received immunosuppressive therapy, 67% responded irrespective of time of initiation of therapy while conservatively managed patients showed no spontaneous remissions. Genomic analysis of mAA identified evidence of clonal haematopoiesis with both persisting and remitting patterns at low allelic frequencies; with more pronounced mutational burden in sAA. Most of the mAA patients have autoimmune pathogenesis similar to those with sAA, but mAA contains a mix of patients with diverse aetiologies. Although progression rates differed between mAA and sAA (P = 0·003), cumulative incidences of mortalities were only marginally different (P = 0·095). Our results provide guidance for diagnosis/management of mAA, a condition for which no current standard of care is established.

Idiopathic aplastic anemia vs hypocellular myelodysplastic syndrome

Proper diagnostic distinction of bone marrow failure syndromes can often be challenging. In particular, for older patients with idiopathic aplastic anemia (AA), differential diagnosis includes myelodysplastic syndrome (MDS), which can atypically present in a hypocellular form. In addition to blasts and overt dysplasia, the presence of chromosomal abnormalities and a spectrum of somatic mutations may be revealing. Both clonal cytogenetic aberrations and somatic mutations most typically correspond to a clonal myelodysplasia, but clonal somatic mutations have also recently been found in AA. True driver myeloid mutations are uncommon in AA. Marrow hypocellularity in AA and occasionally in MDS patients points toward a similar immune mechanism responsible for deficient blood cell production and indicates that cytopenias in early hypocellular MDS might be treated with immunosuppressive modalities. Primary hypocellular MDS has to be distinguished from post-AA secondary MDS, most commonly associated with del7/7q. Post-AA MDS evolves at the rate of about 10% in 10 years, but recent observations suggest that widespread use of eltrombopag may influence the risk of progression to MDS. This complication likely represents a clonal escape, with founder hits occurring early on in the course of AA. A similar mechanism operates in the evolution of paroxysmal nocturnal hemoglobinuria (PNH) in AA patients, but PNH clones are rarely encountered in primary MDS.

Clinical, histopathological and molecular characterization of hypoplastic myelodysplastic syndrome

Diagnostic criteria for hypoplastic myelodysplasic syndrome (h-MDS) have not been clearly established, making the differential diagnosis from other bone marrow failure syndromes (BMF) challenging. In this study, we aimed to delineate clinical, histopathological, and molecular features of h-MDS, based on a large and well-annotated cohort of patients with bone marrow (BM) hypocellularity. The study included 534 consecutive adult patients with hypocellular BM (278 h-MDS and 136 aplastic anemia), and 727 with normo- or hypercellular MDS (n-MDS). Comparison of clinical features of patients with h-MDS as defined by BM cellularity ≤25% (n = 204) or reduced age-adjusted cellularity (n = 74) did not reveal significant differences. We developed a diagnostic score to discriminate h-MDS from non-malignant BMF based on histological and cytological variables with the highest specificity for MDS (h-score). The information from chromosomal abnormalities and somatic mutation patterns was then integrated into a cyto-histological/genetic score (hg-score). This score was able to segregate two groups of h-MDS with a significantly different risk of blast progression (P < 0.001). The integration of cyto-histological and genetic features in adult patients with hypocellular BM facilitated segregation into two distinct groups, one with clinical and genetic features highly consistent with myeloid neoplasm, and one with features more consistent with non-malignant BMF.

MDS overlap disorders and diagnostic boundaries

Myelodysplastic syndromes (MDS) are clonal diseases defined by clinical, morphologic, and genetic features often shared by related myeloid disorders. The diagnostic boundaries between these diseases can be arbitrary and not necessarily reflective of underlying disease biology or outcomes. In practice, measures that distinguish MDS from related disorders may be difficult to quantify and can vary as disease progression occurs. Patients may harbor findings that are not consistent with a single diagnostic category. Several overlap disorders have been formally described, such as the myelodysplastic/myeloproliferative neoplasms (MDS/MPNs). These disorders are characterized by hematopoietic dysplasia with increased proliferation of monocytes, neutrophils, or platelets. They may have mutational profiles that distinguish them from the disorders they resemble and reflect important differences in pathophysiology. MDS also shares diagnostic borders with other diseases. For example, aplastic anemia and hypoplastic MDS can be difficult to distinguish in patients with pancytopenia and bone marrow hypocellularity. Genetic features may help in this regard, because they can identify differences in prognosis and risk of progression. The boundary between MDS and secondary acute myeloid leukemia (sAML) is arbitrarily defined and has been redefined over the years. Genetic studies have demonstrated that sAML clones can precede clinical progression from MDS by many months, suggesting that MDS with excess blasts could be viewed as an overlap between a dysplastic bone marrow failure syndrome and an oligoblastic leukemia. This review will describe the diagnostic boundaries between MDS, MDS/MPNs, sAML, clonal hematopoiesis of indeterminate potential, clonal cytopenia of undetermined significance, and aplastic anemia and how genetic approaches may help to better define them.

Distinct mutation profile and prognostic relevance in patients with hypoplastic myelodysplastic syndromes (h-MDS)

Myelodysplastic syndromes (MDS) are a heterogeneous group of hematologic malignancies. Although most MDS patients have normal or increased BM cellularity (NH-MDS), some have hypocellular BM (h-MDS). The reports concerning the differences in genetic alterations between h-MDS and NH-MDS patients are limited. In this study, 369 MDS patients diagnosed according to the WHO 2008 criteria were recruited. h-MDS patients had lower PB white blood cell and blast counts, and lower BM blast percentages, than those with NH-MDS. h-MDS was closely associated with lower-risk MDS, defined by the International Prognostic Scoring System (IPSS) and revised IPSS (IPSS-R). IPSS-R could properly predict the prognosis in h-MDS (P<0.001) as in NH-MDS patients. The h-MDS patients had lower incidences of RUNX1, ASXL1, DNMT3A, EZH2 and TP53 mutations than NH-MDS patients. The cumulated incidence of acute leukemic transformation at 5 years was 19.3% for h-MDS and 40.4% for NH-MDS patients (P= 0.001). Further, the patients with h-MDS had longer overall survival (OS) than those with NH-MDS (P= 0.001), and BM hypocellularity remains an independent favorable prognostic factor for OS irrespective of age, IPSS-R, and gene mutations. Our findings provide evidence that h-MDS indeed represent a distinct clinico-biological subgroup of MDS and can predict better leukemia-free survival and OS.

A nationwide survey of hypoplastic myelodysplastic syndrome (a multicenter retrospective study)

Hypoplastic myelodysplastic syndrome (hMDS) is a distinct entity with bone marrow (BM) hypocellularity and the risk of death from BM failure (BMF). To elucidate the characteristics of hMDS, the data of 129 patients diagnosed between April 2003 and March 2012 were collected from 20 institutions and the central review team of the National Research Group on Idiopathic Bone Marrow Failure Syndromes, and compared with 115 non-hMDS patients. More RA and fewer CMMoL and RAEB-t in French-American-British (FAB) and more RCUD and MDS-U and fewer RCMD in World Health Organization (WHO) classifications were found in hMDS than non-hMDS with significant differences. The overall survival (OS) and AML progression-free survival (AML-PFS) of hMDS were higher than those of non-hMDS, especially in patients at age ≥50 and of lower risk in Revised International Prognostic Scoring System (IPSS-R). In competing risks analysis, hMDS exhibited decreased risk of AML-progression in lower IPSS or IPSS-R risk patients, and higher risk of death from BMF in patients at age ≥50. Poor performance status (PS ≥2) and high karyotype risks in IPSS-R (high and very high) were significant risk factors of death and AML-progression in Cox proportional hazards analysis.

Recent advances in understanding clonal haematopoiesis in aplastic anaemia

Acquired aplastic anaemia (AA) is an immune-mediated bone marrow failure disorder inextricably linked to clonal haematopoiesis. The majority of AA patients have somatic mutations and/or structural chromosomal abnormalities detected as early as at diagnosis. In contrast to other conditions linked to clonal haematopoiesis, the clonal signature of AA reflects its immune pathophysiology. The most common alterations are clonal expansions of cells lacking glycophosphotidylinositol-anchored proteins, loss of human leucocyte antigen alleles, and mutations in BCOR/BCORL1, ASXL1 and DNMT3A. Here, we present the current knowledge of clonal haematopoiesis in AA as it relates to aging, inherited bone marrow failure, and the grey-zone overlap of AA and myelodysplastic syndrome (MDS). We conclude by discussing the significance of clonal haematopoiesis both for improved diagnosis of AA, as well as for a more precise, personalized approach to prognostication of outcomes and therapy choices.