Features Of Myelodysplastic Syndromes Research Articles

Higher prevalence of poor prognostic markers at a younger age in adult patients with myelodysplastic syndrome – evaluation of a large cohort in India

BackgroundThe karyotype is a major determinant of prognosis in myelodysplastic syndrome (MDS). Details of the cytogenetic profile of MDS in South Asia are limited because cytogenetic services are not widely available.MethodsWe performed a retrospective analysis of the cytogenetic and clinicopathologic profile of adult primary MDS seen consecutively at a tertiary-care centre in South India between 2003 and 2017. Patients were re-categorised according to the 2022 World Health Organisation (WHO) and the International Consensus classifications (ICC).ResultsThere were 936 patients aged 18–86 years (median age 53, 65% males), with MDS with del 5q, low blasts and increased blasts in 7.5%, 58.4% and 34.1% respectively. Clonal abnormalities were seen in 55% of patients, with solitary abnormalities in 29.8% and complex karyotypes (CK, ≥ 3 abnormalities) in 15%. The most frequent abnormalities were monosomy 7/deletion 7q (16.1%), deletion 5q (14.5%), trisomy 8 (11.5%), and deletion 20q (5.1%). Cytogenetic prognosis groups were distributed as follows: very good, 2%; good, 55.6%; intermediate, 16.2%; poor, 15%; very poor, 11.2%. Clinical (IPSS-R) risk stratification (842 patients) showed: very low-risk, 3.9%; low-risk, 30.9%; intermediate-risk, 24.2%; high-risk, 21%; very high-risk, 20%. Age-adjustment (IPSS-RA) raised the very low-risk group to 12.4%; the other groups decreased by 1–3% each.ConclusionThe most significant finding of this cytogenetic analysis of MDS in India is that abnormal karyotypes with poor prognosis markers including monosomy 7 and CK were more frequent than in most other reports, among patients who were overall younger. Trisomy 8, deletion 20q, the IPSS-R intermediate-risk and both high-risk groups were more common than in the West. Trisomy 8 was less common than in South-East Asia while CK and deletion 20q were comparable. Evaluation of such large cohorts highlights the unique features of MDS in different parts of the world. These findings suggest that there could be differences in predisposing factors, environmental or genetic, and emphasise the need for further exploration to better understand the varied nature of MDS.

The E592K variant of SF3B1 creates unique RNA missplicing and associates with high-risk MDS without ring sideroblasts

AbstractAmong the most common genetic alterations in myelodysplastic syndromes (MDS) are mutations in the spliceosome gene SF3B1. Such mutations induce specific RNA missplicing events, directly promote ring sideroblast (RS) formation, and generally associate with a more favorable prognosis. However, not all SF3B1 mutations are the same, and little is known about how distinct hotspots influence disease. Here, we report that the E592K variant of SF3B1 associates with high-risk disease features in MDS, including a lack of RS, increased myeloblasts, a distinct comutation pattern, and a lack of favorable survival seen with other SF3B1 mutations. Moreover, compared with other hot spot SF3B1 mutations, E592K induces a unique RNA missplicing pattern, retains an interaction with the splicing factor SUGP1, and preserves normal RNA splicing of the sideroblastic anemia genes TMEM14C and ABCB7. These data have implications for our understanding of the functional diversity of spliceosome mutations, as well as the pathobiology, classification, prognosis, and management of SF3B1-mutant MDS.

Cutaneous manifestations of myelodysplastic syndrome: A systematic review.

Myelodysplastic syndrome (MDS) may present with specific skin lesions, such as leukaemia cutis, which is a well known poor prognostic marker of leukaemia with a high risk of acute leukaemic transformation. However, less is known regarding non-specific cutaneous manifestations of MDS including the prevalence, types and their prognostic and therapeutic significance, which we aimed to determine through this systematic review. We searched electronic databases (PubMed, Medline and EMBASE) from inception up to 26 January 2023 for studies reporting cutaneous manifestations of MDS. Eighty eight articles (case reports n=67, case series n=21), consisting of 134 patients were identified. We identified 6 common cutaneous manifestations: neutrophilic dermatoses (n=64), vasculitis (n=21), granulomatous (n=8), connective tissue disease (CTD) (n=7; composed of dermatomyositis (n=5), cutaneous lupus erythematosus (n=1), and systemic sclerosis (n=1)), panniculitis (n=4), immunobullous (n=1), and other (n=29). Cutaneous features either occurred at time of MDS diagnosis in 25.3%, preceding the diagnosis in 34.7% (range 0.5-216months), or after diagnosis in 40.0% (range 1-132months). Prognosis was poor (40.2% death) with 34.1% progressing to acute myeloid leukaemia (AML). 50% of those with MDS who progressed to AML had neutrophilic dermatoses (p=0.21). Myelodysplastic syndrome was fatal in 39.2% of neutrophilic dermatoses (median time from onset of cutaneous manifestation: 12months), 50% of vasculitis (7.5months), 62.5% of granulomatous (15.5months) and 14.3% of CTD (7months). Recognition of patterns of cutaneous features in MDS will improve early diagnosis and risk stratification according to subtype and associated prognosis.

The future of myelodysplastic syndrome-patient priorities and outcomes that matter.

Without a definitive curative option available to many patients, learning to live with myelodysplastic syndrome (MDS) and manage symptoms effectively becomes a priority in their care. Anaemia is an almost universal feature of MDS. Individuals suffer differently and better individualisation of care is needed. Most MDS patient information offers scant appreciation for disease heterogeneity, variable response to treatment and each patient's likely trajectory. We undertook a two-part, online workshop to discuss what matters most to people living with MDS. Patients generated questions about their condition which they felt should be addressed by research or change how their care is delivered. Patients voted on the importance of each topic, creating a "prioritised" list of issues. Fourteen participants of varying age and experience took part raising 56 unique questions under the themes of: prognosis; end of life; treatment; supportive care; medical staff training; diagnosis and communication. These reflect the symptoms of MDS, improving quality of life (QoL) and communication. Although haemoglobin (Hb) levels have correlation to QoL, it is widely reported that other factors are important in determining QoL and need for transfusions varies despite stable Hb levels. We showed that Hb level and the need for transfusions is not comparable between different patients and even non-comparable over time meaning that the maximal benefit and timing of transfusions cannot be determined from Hb alone. This workshop highlighted patient dissatisfaction with the "numbers-led" approach and the need for an alternative method to determine when to transfuse.

Pathogenetic Subtypes of Pure Red Cell Aplasia and Therapeutic Management Strategies : A Single Centre Experience in the United Kingdom of 75 Patients over 10 Years

Introduction Pure red cell aplasia (PRCA) is a syndrome characterised by a severe anemia, reticulocytopenia and severe depletion of erythroid precursors in an otherwise unremarkable bone marrow. PRCA arises congenitally in Diamond-Blackfan Anemia and usually presents in childhood. Acquired PRCA can occur at any age, can be transient due to infections such as from parvovirus B19, or more chronic, secondary to autoimmune conditions, malignancies especially thymoma, erythropoiesis stimulating agents, , pregnancy and ABO incompatible hematopoetic stem cell transplantation. PRCA is also known to arise from drug and toxin exposure. Haematological malignancy/clonal disorders for e.g. CLL, MGUS, T-LGLs have well known associations with PRCA. PRCA can also be a feature of myelodysplastic syndrome and can herald evolution to aplastic anemia. Despite the heterogeneity in aetiology, the mainstay of treatment remains immunosuppression with steroids and/or ciclosporin. Here, we report our single centre experience of a large cohort of 75 patients with PRCA, referred to our centre over a 10 year period. Methods Patients with pure red cell aplasia referred to the Department of Hematological Medicine at King's College Hospital were identified by interrogation of the Electronic Patient Record (EPR) and pathology systems. The search terms used were a clinical or pathological diagnosis of ‘pure red cell aplasia’ or ‘PRCA’. Our hospital receives diagnostic samples from the South East of England, therefore data was collected only for patients with clinical information available. Patients (n=33) who developed PRCA post-allogeneic stem cell transplant were excluded. Results A total of 75 patients with both a pathological diagnosis of PRCA and available clinical information were identified, 31 (41.3%) were female. Median age was 51 years (range 9 - 84). The majority of patients had underlying conditions known to be associated with PRCA. Of the haematological conditions, PRCA was most seen in association with MDS (Table 1). Of the 75 patients in our cohort, 82% (61/75) required treatment for PRCA and 57% (43/75) required two or more lines of therapy. In total 25.3% (19/75) patients received corticosteroids as first line therapy. Of those, 75% showed a response, with 50% achieved a complete response. The response rate was less favourable (57%) in those patients in whom ciclosporin was used as first line therapy. Most common second line therapy was Ciclosporin (22.3%) followed by Cyclophosphamide (4%), Sirolimus (2.7%) and Anti-Thymocyte Globulin (1.33%). Of the cohort with an underlying MDS, 52% (11/21) responded to treatment, compared to 65% of those with idiopathic PRCA, likely reflective of the recalcitrant nature of PRCA in MDS. Other therapies received were IVIG, erythropoietin and disease-directed therapy,e.g lenalidomide for MDS with 5q- and thymectomy. Median follow of patients were 42 months.The overall survival of PRCA since last follow up was 50% for the cohort as a whole and 63% for those without an associated malignancy or clonal disorder. D iscussion In this large single centre experience of PRCA, we describe a lower incidence of idiopathic PRCA, lower median age despite a large proportion of MDS and increased incidence in male as compared to published literature. Response to initial therapy was seen in the majority of idiopathic PRCA patients, however response was lower in patients with an underlying malignancy. Of note we identified STAT3 mutations in two patients, highlighting the role of molecular testing and keeping a broad differential diagnosis when presented with this rare condition.

STAG2 Somatic Mutations Are Associated with Specific Dysplastic Megakaryocytic and Myeloid Cell Features in Myelodysplastic Syndrome

Introduction: Although myelodysplastic neoplasms/myelodysplastic syndromes (MDS) are driven by genetic mutations, their diagnosis relies on morphologic evaluation of abnormal hematopoiesis in the bone marrow. Only a small number of genetic abnormalities define bone marrow morphologic features in MDS, such as those harboring SF3B1 mutations and deletions of chromosome 5q. We hypothesized that there are additional genetic alterations and dysplastic morphologic features in MDS that have not been well-described in the literature. We assessed genetic morphologic associations between 50 commonly mutated genes and 10 morphologic features in a cohort of MDS bone marrows with a high degree of dysplasia. We validated and extended these findings in an independent cohort of myeloid neoplasms. STAG2 mutations were strongly associated with specific dysplastic megakaryocytic and myeloid cell features in both cohorts. Methods: We reviewed bone marrow core biopsies and aspirates from 272 MDS clinical cases (2013-2014) and selected 89 for further study based on the presence of prominent dysplastic features. Each case was independently evaluated by two pathologists for the following dysplastic features: small hypolobated megakaryocytes, widely separated megakaryocyte nuclei; abnormal myeloid nuclear segmentation, myeloid hypogranulation, Auer rods; ring sideroblasts, erythroid binucleation, irregular erythrocyte nuclei, erythroid nuclear cytoplasmic dyssynchrony, and erythroid karyorrhexis. Targeted next generation sequencing was performed using a 50 gene panel comprising the most common somatic myeloid mutations. For each dysplastic feature, univariate risk analysis was used to identify genetic mutations for use in multivariable analysis. Significant associations were validated through blinded morphologic review in an independent cohort of 155 bone marrow biopsies of myeloid neoplasms, comprised of 83 myelodysplastic syndromes, 33 myelodysplastic/myeloproliferative neoplasms and 39 acute myeloid leukemias, diagnosed between 2014 and 2019 and selected for mutations identified in the initial discovery cohort ( STAG2, RUNX1, SRSF2, ASXL1 and SETBP1) . Results: Pairwise analyses demonstrated broad patterns of genetic associations with myeloid/megakaryocytic dysplasia versus erythroid dysplasia (Panel 1). In multivariable analysis, STAG2 and SRSF2 mutations were significantly associated with megakaryocytes with widely separated nuclei ( STAG2, OR = 25.5, 95% CI [4.17, 493.5], P = 0.003; SRSF2, OR = 10.1, 95% CI [2.07, 75.0], P = 0.008). Mutations in STAG2 and SETBP1 were significantly associated with abnormal myeloid nuclear segmentation ( STAG2, OR = 7.08, 95% CI [1.94, 28.0], P = 0.003; SETBP1, OR = 12.2, 95% CI [1.29, 267.4], P = 0.04). Furthermore, STAG2 mutations were significantly associated with myeloid cell hypogranulation (OR = 12.7, 95% CI [3.10, 86.3], P = 0.002). Because this initial cohort was relatively small, which led to wide confidence intervals suggesting estimation instability, we validated and extended these findings in an independent cohort of myeloid neoplasms. In the validation cohort (enriched for mutations in STAG2, SRSF2, and SETBP1), STAG2 mutations were significantly associated with separated megakaryocyte nuclei (univariate OR = 4.18, 95% CI [1.98, 8.80], P = 0.0002), abnormal myeloid nuclear segmentation (univariate OR = 3.47, 95% CI [1.47, 8.22], P = 0.008), and myeloid cell hypogranulation (multivariable OR = 5.28, 95% CI [2.18, 13.4], P = 0.0003) (Panel 2). In contrast, morphologic associations with SRSF2 and SETBP1 mutations were not validated. Conclusion: STAG2 genetic alterations are strongly associated with the presence of separated megakaryocyte nuclei, abnormal myeloid nuclear segmentation and myeloid cell hypogranulation in MDS. Our data suggest that STAG2 may affect pathways involved in nuclear shape control and secondary granule formation. Panel 1: Pairwise associations between gene mutation and bone marrow morphology in MDS. N, number. Panel 2: Multivariable (black) and univariate (white) analysis in two independent cohorts showing significant gene associations with megakaryocytes with separated nuclei, abnormal myeloid nuclear segmentation, and myeloid cell hypogranulation. CI, confidence interval.

AG-946, an Activator of Pyruvate Kinase, Improves Ineffective Erythropoiesis in the Bone Marrow of Mouse Models of Myelodysplastic Syndromes

Background: Myelodysplastic syndromes (MDS) are a heterogeneous group of hematologic malignancies characterized by ineffective erythropoiesis. Anemia is the most common cytopenia and major clinical problem in MDS. Acquired pyruvate kinase (PK) deficiency has been observed in MDS, and a direct impact on the glycolytic pathway in the pathogenesis of anemia associated with MDS has been demonstrated. AG-946 is an investigational, small-molecule, allosteric activator of PK that has the potential to enhance red blood cell (RBC) functionality and survival by increasing glycolysis and adenosine triphosphate (ATP) production, and improve differentiation of erythroid cells in bone marrow, potentially improving anemia caused by ineffective erythropoiesis in MDS. Previous findings showed that RBCs from patients with MDS treated ex-vivo with AG-946, led to an increase in PK activity. Here, we used two MDS-related mouse models to evaluate the effects of the PK activator AG-946 in this mechanism of anemia. Aim: Evaluate the effect of AG-946 treatment on impaired erythropoiesis in the bone marrow of two mouse models of MDS. Methods:NUP98-HOXD13 (NHD13) is a fusion gene mutation observed in some patients with MDS. Mouse models with this mutation develop key characteristics of MDS such as impaired erythropoiesis and progressive anemia leading to malignant leukemia around 12 months of age. Male and female NHD13 and C57BL/6J mice were placed on 0.006% AG-946 (approximate dose 10 mg/kg/day) formulated diet starting at 10 months given ad libitum and continuing for 3 months. Numbers of animals for wild type (WT) Control, WT AG-946, NHD13 Control, NHD13 AG-946 were 10, 10, 13, and 11, respectively.Polg D257A (Polg) mouse model, while not a mutation observed in patients with MDS, does display many key features of MDS, such as impaired erythropoiesis and progressive anemia. Male and female Polg mice were placed on 0.006% AG-946 (approximate dose 10 mg/kg/day) formulated diet starting at 4 months given ad libitum and continuing for 8 months. Numbers of animals for WT Control, WT AG-946, Polg Control, Polg AG-946 were 10, 10, 19, and 18, respectively. Bone marrow from 1 femur per mouse was collected and analyzed by flow cytometry. Bone marrow cell pellets were washed and treated with ACK lysing buffer prior to staining. Samples with fewer than 1000 Ter119+ events were removed from analysis due to insufficient cell count. Bone marrow erythroblast populations were gated using Single Cells/Live/B220-/Ter119+/CD44 vs FSC, which were then gated into three populations: basophilic erythroblasts (BasoE), polychromatic erythroblasts (PolyE), and orthochromatic erythroblasts and reticulocytes (OrthoE + Retic). Results:No differences in any erythroblast populations were observed between untreated WT and NHD13 mice. No changes in the BasoE population were observed in WT or NHD13 mice. The PolyE population in NHD13 mice treated with AG-946 was significantly decreased compared with both the NHD13 and WT untreated mice (p=0.0021 and 0.0003, respectively). NHD13 mice treated with AG-946 showed significant increases in the OrthoE + Retic populations over the untreated NHD13 mice (p=0.0275).No differences in BasoE or OrthoE + Retic populations were observed between untreated WT and Polg mice while the PolyE population was significantly decreased in Polg mice compared with WT (p<0.0001). The BasoE population was significantly decreased in Polg mice treated with AG-946 compared with untreated Polg (p=0.0002). No difference in PolyE population was observed in Polg mice with AG-946. OrthoE + Retic population was significantly increased in Polg mice treated with AG-946 compared with WT and Polg untreated mice (p=0.0001 and 0.0304, respectively). Data graphed as average +/- SEM. Conclusions: Our data suggest AG-946 treatment improves erythroblast maturation in two MDS mouse models as demonstrated by a reduction in early-stage erythroblasts (BasoE, PolyE) coupled with an increase in late-stage erythroblast populations (OrthoE + Retic). These data are the first to suggest that PK activation by AG-946 could improve ineffective erythropoiesis in MDS.

Clinical characteristics of Japanese patients with myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis.

Myelodysplastic/myeloproliferative neoplasm with ring sideroblasts and thrombocytosis (MDS/MPN-RS-T) is a rare disease, which presents with features of myelodysplastic syndromes with ring sideroblasts and essential thrombocythemia, as well as anemia and marked thrombocytosis. SF3B1 and JAK2 mutations are often found in patients, and are associated with their specific clinical features. This study was a retrospective analysis of 34 Japanese patients with MDS/MPN-RS-T. Median age at diagnosis was 77 (range, 51-88) years, and patients had anemia (median hemoglobin: 9.0g/dL) and thrombocytosis (median platelet count: 642 × 109/L). Median overall survival was 70 (95% confidence interval: 68-not applicable) months during the median follow-up period of 26 (range: 0-91) months. A JAK2V617F mutation was detected in 46.2% (n = 12) of analyzed patients (n = 26), while an SF3B1 mutation was detected in 87.5% (n = 7) of analyzed patients (n = 8). Like those with myelodysplastic syndromes or myeloproliferative neoplasms, patients often received erythropoiesis-stimulating agents and aspirin to improve anemia and prevent thrombosis. This study, which was the largest to describe the real-world characteristics of Japanese patients with MDS/MPN-RS-T, showed that the patients had similar characteristics to those in western countries.

Distinct Clinical and Prognostic Features of Myelodysplastic Syndrome in Patients from the Middle East, North Africa, and Beyond: A Systemic Review.

Myelodysplastic syndrome (MDS) describes a group of bone marrow malignancies with variable morphologies and heterogeneous clinical features. The aim of this study was to systematically appraise the published clinical, laboratory, and pathologic characteristics and identify distinct clinical features of MDS in the Middle East and North Africa (MENA) region. We conducted a comprehensive search of the PubMed, Web of Science, EMBASE, and Cochrane Library databases from 2000 to 2021 to identify population-based studies of MDS epidemiology in MENA countries. Of 1935 studies, 13 independent studies published between 2000 and 2021 representing 1306 patients with MDS in the MENA region were included. There was a median of 85 (range 20 to 243) patients per study. Seven studies were performed in Asian MENA countries (732 patients, 56%) and six in North African MENA countries (574 patients, 44%). The pooled mean age was 58.4 years (SD 13.14; 12 studies), and the male-to-female ratio was 1.4. The distribution of WHO MDS subtypes was significantly different between MENA, Western, and Far East populations (n = 978 patients, p < 0.001). More patients from MENA countries were at high/very high IPSS risk than in Western and Far East populations (730 patients, p < 0.001). There were 562 patients (62.2%) with normal karyotypes and 341 (37.8%) with abnormal karyotypes. Our findings establish that MDS is prevalent within the MENA region and is more severe than in Western populations. MDS appears to be more severe with an unfavorable prognosis in the Asian MENA population than the North African MENA population.

Correlation of Mutational Profiles and Cytogenetics with Morphologic Dysplasia in Myelodysplastic Syndromes

Introduction: Myelodysplastic syndromes (MDS) are a spectrum of clonal bone marrow failure disorders demonstrating cytopenias, dysplasia, and risk of progression. Although ~50% of MDS patients have normal karyotype (NK), a subset of MDS exhibits genetic alterations that result in an abnormal karyotype. However, the relationship between the molecular landscape and histologic features in MDS have not been well explored. Using next generation sequencing (NGS) and cytogenetics, we sought to correlate genetic abnormalities in MDS with morphologic dysplasia. Methods: After IRB approval, we retrospectively identified NGS studies performed with a 164 gene panel in patients with MDS at Stanford (2018-2021). Molecular and cytogenetic data were collected for 225 MDS patients. Peripheral blood and bone marrow (BM) slides were collected from 61 patients for histological review. As controls, 32 staging BMs were obtained from untreated lymphoma patients. A hematopathologist performed a blinded intense morphologic review. A subset of cases was reviewed by 2 other hematopathologists and the intraclass correlation coefficient (ICC) was calculated to evaluate concordance. The degree of dysplastic features and overall dysplasia was scored. The standardized mean difference (SMD) was calculated to quantify the degree of dysplasia between comparison groups. Statistical analysis was performed using R (3.6.3); p value < 0.05 was considered statistically significant. Results: MDS cases had higher degrees of dysplasia than control cases in megakaryocytic (median 37.5% vs 0%), granulocytic (median 20% vs 0%), and erythroid (median 10% vs 0%) lineages. To assess specificity, using a cutoff of 10%, 1/31 control cases (3.1%) showed megakaryocytic dysplasia, 2/32 (6.3%) had erythroid dysplasia, while none showed granulocytic dysplasia. Dysplasia in > 2 lineages in >10% of cells was specific for MDS, detected in 49/61 (80.3%) of MDS cases vs 0/32 control cases (Table 1). Within the MDS group, lack of multilineage dysplasia was more common in NK (8/25; 32%) vs non-NK (3/36; 8.3%), suggesting MDS-NK is morphologically subtle. Using a cutoff of 10%, 13/25 (52%) NK lacked granulocytic dysplasia vs 10/36 (27.8%) in non-NK, 8/25 (32%) of NK lacked erythroid dysplasia vs 10/36 (27.8%) in non-NK, and 5/25 (20%) NK lacked megakaryocytic dysplasia vs 3/35 (8.3%) in non-NK. The most strongly associated dysplastic features for MDS included erythroid megaloblastic change (SMD=1.25), erythroid nuclear features (SMD=1.041), atypical megakaryocyte nuclei (SMD=1.189), separated megakaryocyte nuclei (SMD=1.131), and hypogranulated granulocytes (SMD=1.096). Based on 10 MDS and 5 control cases, rough concordance on overall dysplasia was demonstrated among 3 hematopathologists. Granulocytic dysplasia showed the highest reproducibility (ICC for granulocytic = 0.948, erythroid = 0.547, megakaryocytic = 0.531). The percent of cells with dysplasia in the MDS cohort did not correlate with number of mutations. The overall number of mutations between MDS with NK and non-NK were relatively similar (Figure 1). The non-NK group exhibited a greater frequency of pathogenic TP53 variants than NK (31.5% vs 2.6%, p < 0.0001). Conversely, SF3B1 and TET2variants occurred more frequently in the NK cohort than non-NK (SF3B1: 32.5% vs 12.6%; TET2: 29.8% vs 12.6%, both p values < 0.003). In MDS cases with a TET2 variant, NK was associated with a significantly higher total number of mutations than non-NK cases (median [IQR]: 5[5-7] vs 4[3-6], p = 0.031). Using Random Forest models, exploratory multivariate analysis identified the presence of mutations in TP53, SF3B1, TET2, and overall megakaryocytic, granulocytic, and erythroid dysplasia as the prominent parameters that distinguished NK from non-NK MDS cases. There was no significant difference in age at diagnosis between NK and non-NK MDS in all NGS cases (median age 74 vs 70, p = 0.10) and morphologically scored cases (median age 70 in both groups). Conclusion: Our study demonstrates that granulocytic dysplasia was the most specific morphologic finding for MDS with high reproducibility among 3 hematopathologists. Detection of dysplasia in > 2 lineages in >10% cells was also specific for MDS, while MDS-NK appear morphologically subtle. Mutations in TET2 were more frequent in MDS-NK. Our findings highlight the importance of NGS and histopathology in helping establish a diagnosis of MDS-NK. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

The Transcriptional Factor ONECUT3 Is a Driver and Therapeutic Target for Complex Karyotype MDS

Myelodysplastic Syndrome (MDS) represents a group of clonal hematopoietic disorders characterized by ineffective hematopoiesis and morphological dysplasia. Chromosomal instability is a prominent biological feature of MDS, with over 50% of patients with MDS harboring chromosomal abnormalities or complex karyotypes (CK). The mechanisms underlying mitotic and chromosomal defects associated with MDS remain elusive. In recent years, most studies have focused on the associations of TP53 mutation or deactivation with CK (Bernard et al, Nat Med 2020). Hitherto, besides TP53, few genes were reported associated with cytogenetic aberration in MDS (Bernard et al, Nat Med 2020). To fill this knowledge gap, RNA-Seq was conducted to find the CK-associated transcriptional factors and showed that ONECUT3 is significantly upregulated in MDS with CK, independent of TP53 mutation. Intriguingly ONECUT3 predicted poor survival of MDS patients. Our work indicates that ONECUT3 overexpression gave rise to multinucleated variants and complex karyotype in both TP53-KO MEF and TP53-WT MEF. Mechanistically, overexpressed ONECUT3 transcriptionally activated INCENP and CDCA8 through the direct binding to unique genomic regions, which was performed by RNA-seq and ChIP-seq concurrently. Upregulations of INCENP and CDCA8 induced the assembly of chromosome passenger complex (CPC) that were accumulated in addition to cell equator and midbody during the mitotic phases, consequently causing cytokinesis failure and defective chromosome segregation. As ONECUT3-OE cells attenuated chemo-sensitivity, we explored whether the compounds targeting the ONECUT3-CPC axis could alleviate chemoresistance. Homeobox domain was identified to function as the DNA binding by domain-deleted mutants and structural modeling (AlphaFold - DeepMind). One novel lead-compound C5484617 was later identified by protein structure-based drug virtual screening, to specifically target ONECUT3 and synergically re-sensitize the hypomethylating reagents in MDS with minimized cytotoxicity. In summary, the current study demonstrated that CK-associated TF ONECUT3 upregulates the CPC components in MDS, leading to mitotic defects and decreasing chemo-sensitivity. The Aurora B inhibitor (Barasertib) and a lead compound (C5484617) could help increase the sensitivity of MDS cells to HMA. Our findings are mechanistically significant and of great clinical relevance. The present investigation provides the foothold for further studies to identify novel approaches for MDS patients with limited therapeutic options. Moreover, our findings may be implemented for other cancer types, given that CK/genomic instability is a hallmark of cancer. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Differentiation Scoring (DS) Derived from Cellworks Computational Omics Biology Model (CBM) Predicts Response to Hypomethylating Agents (HMA) and Patient Survival in Myelodysplastic Syndrome (MDS)

Background: Differentiation arrest resulting from aberrant methylation represents a key pathogenic and phenotypic feature of MDS. Hypomethylating agents (HMA) can reverse epigenetic dysregulation, but as single agents fail to control the disease in approximately 50% of patients, many of whom progress to AML and carry a dismal prognosis. We hypothesized that Differentiation Scoring (DS) derived from Cellworks Computational Omics Biology Model (CBM) of each patient's genomic aberrations could serve as a biomarker to predict response to HMA. Methods: We studied 169 MDS patients treated with azacytidine (n = 86) or decitabine (n = 83) whose genomic aberrations and clinical outcomes were available from public databases. Biosimulation of the disease state was computationally derived from pathways that were up- or down-regulated by individual genomic aberrations. DS was defined as the ratio of the quantified impact of key differentiation biomarkers in myeloid malignancies (CEBPA, GATA1, SPI1 and ITGAM) divided by the impact of HOXA9 transcription, a known repressor of differentiation, and normalized on a log2 scale. We also used CBM to determine the change in DS attributable to HMA to define an efficacy score (ES) as a parameter of drug response. A Pearson correlation coefficient was obtained using the two variables. DS in clinical responders (R) and non-responders (NR) was evaluated with the Student t-test. We defined DS > 1.5 as DS-high and < 1.5 as DS-low. Survival data were available for 101 patients and correlated with DS-high (n=49) and DS-low (n=52) groups using a KM-curve. Results: Median age of this cohort was 69 years (range, 20-87 years), including 56 females, 111 males, and 2 of unknown sex. Regarding HMA response, 62 patients were R while 107 were NR. Prior to therapy, 86 patients had DS-high and 83 had DS-low scores. Post-treatment DS were correlated with HMA ES (R = 0.58, p < 2.2e-16), and showed a favorable HMA response for DS-high patients. Biosimulation showed the incremental benefit on DS of HMA was greater for people with DS-high than DS-low scores (44% vs 16%, p = 7.51 e-17). Median DS was higher in R than NR (p=0.00232). Patients with DS-high scores had superior survival compared to those with DS-low scores (log rank p = 0.0016). (Figure 1a) Different genomic aberrations contributed to the DS scores. DS-high patients had more TP53 mutations, 17p del, 8q amp, and 5q del. On the other hand, DS-low patients more often had mutations in ASXL1, SRSF2, RUNX1, DNMT3A, EZH2, NF1, NRAS, CBL, or 7q deletion. (Figure 1b) Loss of TP53 due to mutation or deletion upregulates DNMT1 and silences HOXA9 transcription, leading to DS-high scores. KAT6A (8q) amp also upregulates EZH2 and CpG methylation, while 5q del causes GATA1 transcription, increasing CpG methylation via SALL4 to produce high ß-catenin signaling that led to DS-high scores. By contrast, 7q loss, ASXL1, SRSF2, and EZH2 mutations downregulated EZH2, diminished CpG methylation and unsilenced HOXA9 transcription. As a result, HOXA9 arrested differentiation results in DS-low scores. Additionally, NF1 or NRAS mutations upregulate ERK signaling which inhibits CEBPA, and also caused DS-low scores. Conclusions: Computational biosimulation based on patients’ individual genomic aberrations reveals a spectrum of DS among patients with MDS. DS strongly predicted HMA response. In general, NR had lower DS and survival than DS-high patients. While patients with DS-low scores might have fared even worse without HMA therapy, we propose that DS-low patients should be considered for novel combination therapy at the time of diagnosis given their unsatisfactory outcomes with HMA therapy as a single agent. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Pediatric-Specific Patterns of Clonal Evolution Arising from Acquired Aplastic Anemia

Introduction Acquired aplastic anemia (aAA) occurs in both children and adults, though pathophysiology and clinical outcomes differ significantly by age. While clinical testing for paroxysmal nocturnal hemoglobinuria (PNH) clones is routine, targeted next generation sequencing (NGS) for myelodysplastic syndrome (MDS) associated variants has only recently been implemented. Furthermore, single nucleotide polymorphism array (SNP-A) assessing for copy neutral loss of heterozygosity in the human leukocyte antigen (HLA) region on chromosome 6p (6p CN-LOH) and HLA NGS assessing for allele specific loss of function (LoF) mutations, which together are seen in up to 25% of aAA cases, are only now being considered for clinical use. Recent studies have reported on the frequency and overlap of these 3 types of clonal evolution (PNH, MDS-associated, HLA-targeting) in adult aAA cohorts, but none focus specifically on pediatric patients, whose MDS-associated clonal evolution patterns are distinct. Delineating patterns of clonal hematopoiesis in pediatric aAA to determine whether evolution driven by immune escape (PNH and HLA loss) affects likelihood of MDS development is critical for personalizing therapeutic options. Thus, we aimed to describe the frequency, clinical significance, and overlap of clonal evolution including PNH, HLA loss, and MDS-associated gene mutations in a pediatric cohort of aAA patients. Methods This study identified 85 pediatric aAA patients treated at Children's Hospital of Philadelphia (CHOP) and enrolled on the IRB-approved CHOP/Penn BMF Registry and Repository in whom clinical testing for all patterns of clonal hematopoiesis was available or could be performed with biorepository samples. PNH flow cytometry was performed clinically in all cases; subjects with PNH > 0.05% in the granulocyte fraction were considered as having a PNH clone. Peripheral blood and bone marrow samples were used for SNP-A, HLA-NGS, and an institutional somatic mutation NGS panel for hematological malignancies encompassing 118 genes. Descriptive and contingency statistical analyses along with Fisher's Exact Test were performed using SAS (Cary, NC). Results Demographic composition of the 85 pediatric subjects with aAA included a median age of 10.7 years (1.7-20.8), male/female ratio of 59%/41%, and a representative race/ethnicity distribution (Table 1). In total, 66% displayed at least one clonal event. As expected, PNH clones were most common, present in 45% (38/85) of the cohort. An additional 16 (19%) exhibited acquired HLA loss by 6p CN-LOH (n=6), allele specific LoF mutations (n=6), or both (n=4). Fifteen (18%) had clonal hematopoiesis associated with MDS, of whom 3 had cytogenetic lesions that progressed to clinical MDS (3.5%), and 12 developed no morphologic features of MDS but demonstrated a total of 14 mutations in MDS-associated genes (BCOR/BCORL1 n=6, KMT2C/KMT2D n=3, RUNX1 n=1, ASXL1 n=1, SRSF2 n=1, PRPF8 n=1, CALR n=1). Critically, pediatric subjects with aAA who developed HLA loss did not develop MDS-associated mutations, with no patient demonstrating both subtypes of clonal events (Figure 1). In contrast, PNH and MDS-associated clonal events overlapped in 11% of the overall cohort. In total, 60% of patients with MDS-associated clonal hematopoiesis also possessed PNH clones, and 23% of patients with detectable PNH clones demonstrated at least one MDS-associated clonal event. Only 3.53% (n=3) of the cohort demonstrated both PNH and HLA loss, and PNH clone size was < 1% in all 3 patients. Furthermore, patients with HLA loss were significantly less likely to have PNH clones than those without HLA somatic alterations (19% vs 51%, p = 0.026). Correlations between patterns of clonal hematopoiesis and clinical outcomes will be presented. Concalusions Pediatric aAA patients treated with IST are at risk for developing MDS and hemolytic PNH. Presence and evolution of clonal hematopoiesis influenced decisions to pursue IST versus alternative donor transplant. Importantly, our study demonstrates that occurrence of clonal hematopoiesis by HLA loss does not increase and may even decrease the risk of developing MDS-associated or PNH clones. This finding strongly suggests that treatment decisions for aAA patients whose only clonal event is HLA loss need not be considered distinctly from patients with no clonal changes. Figure 1View largeDownload PPTFigure 1View largeDownload PPT Close modal

Acquired and hereditary bone marrow failure: A mitochondrial perspective.

The disorders known as bone marrow failure syndromes (BMFS) are life-threatening disorders characterized by absence of one or more hematopoietic lineages in the peripheral blood. Myelodysplastic syndromes (MDS) are now considered BMF disorders with associated cellular dysplasia. BMFs and MDS are caused by decreased fitness of hematopoietic stem cells (HSC) and poor hematopoiesis. BMF and MDS can occur de novo or secondary to hematopoietic stress, including following bone marrow transplantation or myeloablative therapy. De novo BMF and MDS are usually associated with specific genetic mutations. Genes that are commonly mutated in BMF/MDS are in DNA repair pathways, epigenetic regulators, heme synthesis. Despite known and common gene mutations, BMF and MDS are very heterogenous in nature and non-genetic factors contribute to disease phenotype. Inflammation is commonly found in BMF and MDS, and contribute to ineffective hematopoiesis. Another common feature of BMF and MDS, albeit less known, is abnormal mitochondrial functions. Mitochondria are the power house of the cells. Beyond energy producing machinery, mitochondrial communicate with the rest of the cells via triggering stress signaling pathways and by releasing numerous metabolite intermediates. As a result, mitochondria play significant roles in chromatin regulation and innate immune signaling pathways. The main goal of this review is to investigate BMF processes, with a focus mitochondria-mediated signaling in acquired and inherited BMF.

P1728: THE FUTURE OF MYELODYSPLASTIC SYNDROME – PATIENT PRIORITIES AND OUTCOMES THAT MATTER

Background: Without a definitive curative option available to many patients, learning to live with myelodysplastic syndrome (MDS) and manage symptoms effectively becomes a priority in their care. Anaemia is an almost universal feature of MDS but other cytopenias are common and may be linked to bleeding and infection. Individuals suffer differently and better individualisation of care is needed. Most MDS patient information offers scant appreciation for disease heterogeneity, variable response to treatment and each patient’s likely trajectory. Aims: We undertook to discuss what matters most to people living with MDS and provide feedback on discussions in patient support programmes. The aim was to inform lived experience views on research prioritisation in MDS. Methods: We conducted a 2-part interactive online workshop using Zoom and the online platform Miro, with the assistance of a skilled technical facilitator, to replicate a face-to-face environment (eg white board, post-it notes and sticky dots for voting). Patients were invited to generate questions about their condition which they felt should be addressed by research or a change in how their care is delivered. These were then grouped into themes, and reframed to create individual non-overlapping topics. Using a model inspired by the James Lind Alliance Priority Setting Partnerships, patients voted on the importance of each topic, creating a final “prioritised” list of issues. Results: 14 participants of varying age and experience took part raising 56 unique questions under the themes of: Prognosis; End of life; Treatment; Supportive Care; Medical Staff Training; Diagnosis; Communication; Organisations; resource sharing. Using the voting system, patients prioritised 14 key outcomes (shown in Figure 1). These reflect the symptoms of MDS, improving quality of life (QoL), communication, access to healthcare professionals and individualising care. Image:Summary/Conclusion: There are few studies in MDS where QoL is the primary outcome, hence the paucity of evidence around best practice when prioritising this. Given the pervasiveness of anaemia in MDS, managing this, and subsequent fatigue is of vital importance. Although haemoglobin (Hb) levels have been found to be correlated to QoL, it is widely reported that other factors are important in determining QoL and need for transfusions can vary despite a stable Hb level. Indeed, a key finding from patient discussions showed that Hb levels and the need for transfusions is not comparable between different patients and even non-comparable over time meaning that the maximal benefit and timing of transfusions cannot be determined from Hb level alone. Better communication with patients can ensure transfusions are given to improve symptoms. Previously, evaluation of success of transfusion and the clinical decision to transfuse has been determined only by the effect on Hb levels. This workshop highlighted patient dissatisfaction with the ‘numbers-led’ approach and the need for an alternative method to determine when to transfuse. While studies show using liberal transfusion targets improve QoL there are conflicting results showing a prolonged increase in Hb requires more transfusions which would in turn require more time in hospital. Further research is required to define optimal transfusion policies and improved use of blood products alongside other key outcomes highlighted in this workshop. There is growing evidence that treatment needs to be individualised and with the growing use of lifestyle monitoring devices such as smartwatches, this wealth of information could be utilised to determine transfusion need.

DNMT3A R882 Mutations Confer Unique Clinicopathologic Features in MDS Including a High Risk of AML Transformation

DNMT3A mutations play a prominent role in clonal hematopoiesis and myeloid neoplasms with arginine (R)882 as a hotspot, however the clinical implications of R882 vs. non-R882 mutations in myeloid neoplasms like myelodysplastic syndrome (MDS) is unclear. By data mining with publicly accessible cancer genomics databases and a clinical genomic database from a tertiary medical institution, DNMT3A R882 mutations were found to be enriched in AML (53% of all DNMT3A mutations) but decreased in frequency in clonal hematopoiesis of indeterminate potential (CHIP) (10.6%) or other myeloid neoplasms including MDS (27%) (p<.001). Next with the largest cohort of patients with DNMT3A R882 mutant MDS known to date from multiple institutions, DNMT3A R882 mutant MDS cases were shown to have more severe leukopenia, enriched SRSF2 and IDH2 mutations, increased cases with excess blasts (47% vs 22.5%, p=.004), markedly increased risk of AML transformation (25.8%, vs. 1.7%, p=.0001) and a worse progression-free survival (PFS) (median 20.3, vs. >50 months, p=.009) than non-R882 mutant MDS cases. DNMT3A R882 mutation is an independent risk factor for worse PFS, and importantly the differences in the risk of AML transformation between R882 vs. non-R882 mutant patients cannot be explained by different treatment approaches. Interestingly the higher risk of AML transformation and the worse PFS in DNMT3A R882 mutant MDS cases are mitigated by coexisting SF3B1 or SRSF2 mutations. The unique clinicopathologic features of DNMT3A R882 mutant MDS shed light on the prognostic and therapeutic implications of DNMT3A R882 mutations.

Acute Myleoid Leukaemia t(8:21)- A Close Differential Diagnosis to Myelodysplastic Syndrome with Excess Blasts 2: A Case Report

Acute Myeloid Leukaemia (AML) with t(8;21) (q22;22) is a distinct, rare type of AML, generally occurs in young patients which has a favorable prognosis. It is found in approximately 5% cases of all AML. This translocation (8;21) usually correlates with specific morphological features which include large blasts with Auer rods and large Pseudo-Chediak-Higashi granules in neutrophils. These features are also seen in myelodysplasia related changes, hence should be differentiated as the latter have worse prognosis. Detection of chromosomal abnormalities by cytogenetics is very important for risk stratification and prognosis. Hence, authors reports a very unusual case of AML t(8;21) in a 32-year-old female patient presented with features of Myelodysplastic Syndrome (MDS) with Excess Blasts-2.

Whole Transcriptome Analysis Identifies Distinct Gene Expression Profiles between SF3B1mut and SF3B1 wt Myelodysplastic Syndrome with Ring Sideroblasts

Background and aims - The 2016 revised WHO classification incorporated somatic mutation in SF3B1 spliceosome gene within the diagnostic criteria of myelodysplastic syndrome (MDS) with ring sideroblasts (RS). However, SF3B1wt MDS-RS display significantly different clinical features and outcome from those of SF3B1mut MDS-RS. Recently, the recognition of SF3B1-mutant MDS as a distinct nosologic entity has been proposed to overcome this limitation.Methods - To evaluate the biological relevance of this proposal, we studied a consecutive cohort of 132 MDS with RS >5% using a pangenomic approach (targeted-DNA sequencing, genome-wide copy number variation analysis and bulk RNA-sequencing of CD34+ bone marrow mononuclear cells). 16 age-matched healthy individuals and 43 MDS-SLD/MLD negative for both splicing mutation and RS were included in this study as controls.Results - Unsupervised clustering analysis based on mutation profiles identified two major clusters predicted by SF3B1 mutation (87 MDS-RS-SF3B1mut and 45 MDS-RS-SF3B1wt). The most recurrently mutated genes in MDS-RS-SF3B1wt were TP53(40%), SRSF2(38%), TET2 (33%), ASXL1 (21%) and DNMT3A (12%). SRSF2 and TP53 mutations were found to be mutually exclusive with SF3B1 (p-value <0.05), whereas no difference was found in TET2, DNMT3A and ASXL1 frequencies between MDS-RS-SF3B1 mutand MDS-RS-SF3B1wt subgroups. TP53-mutated MDS-RS exhibited shorter overall survival (median 1.3 years, log-rank p-value<0.0001) compared to SF3B1mut (median 7.6 years), SRSF2mut (median 3.4 years) and MDS-RS without the abovementioned aberrations (median 4.4 years). Notably, allelic imbalances analysis of oncogenic variants identified a significant enrichment of TP53 biallelic inactivation in MDS-RS-SF3B1wt (64% vs 0, p<0.01).Differential gene expression analysis results were incorporated into a specific expression signature highly predictive of MDS-RS-SF3B1 mutand MDS-RS-SF3B1wt subgroups (Figure 1). The resulting gene clusters were classified in RS-specific genes (cluster 1 and 2) and SF3B1-specific genes (cluster 3 and 4). RS-specific genes comprising heme and hypoxia genes were enriched (Figure 2AB) and correlated with RS percentage (p<0.01). Pathway analysis revealed a specific downregulation of adhesion molecules and an upregulation of G-protein coupled receptor signaling molecules in MDS-RS-SF3B1mut. Among SF3B1-specific genes (Figure 2CD), we confirmed ABCB7 downregulation and identified new molecular targets that may concur to the pathophysiology of SF3B1-driven myeloid neoplasms.Conclusions - This study contributes to unveil molecular features of SF3B1-mutant MDS and provides further evidence to support recognition of somatic SF3B1 mutation as a disease-defining genetic lesion. DisclosuresPapaemmanuil: Isabl Technologies: Divested equity in a private or publicly-traded company in the past 24 months; Kyowa Hakko Kirin Pharma: Consultancy.

A Focus on Phenotype and Genotype: Racial /Ethnic Disparities in Myelodysplastic Syndromes

Background: There is a paucity of research on racial and ethnic disparities in myelodysplastic syndromes (MDS). Research focused on racial and ethnic disparities for MDS is essential to improve knowledge and understanding to deliver racial and ethnic sensitive care. There are limited studies that delineate the incidence of cytogenetic and molecular features of MDS by race and ethnicity (Yan, et al. 2021, Ramadan, et al.,2016). The aim of this abstract is to report the difference in clinical phenotype, genotype and outcomes of White, Black and Hispanics from a large MDS data base.Methods: Adult patients were identified through the Moffitt Cancer Center MDS data base and divided into racial/ethnic categories. Fisher exact test and chi-square tests were used to compare categorical variables. Univariate survival analysis was estimated using the Kaplan-Meier method.Results: From analysis of 4414 patients with MDS, 4131 (93%) were White, 116 (3%) Black and 167 (4%) Hispanic. Table-1 summarizes baseline characteristics. There were more Black and Hispanic women diagnosed with MDS (p < .001). Black and Hispanic patients were younger at diagnosis (p<0.01), Hispanic patients had a lower platelet count at baseline (p=0.02). There were no racial differences in WHO 2016 MDS classification or disease risk according to R-IPSS. Black MDS patients had less complex karyotype (p<0.05) while abnormalities in chromosome 5 were more common in White patients 785(19.6%, p<0.05).Table-2 summarizes somatic mutations (SM) landscape among the different racial groups, IDH2 SM (p=0. 01) and NPM-1 SM (p=.004) were more common in Black MDS patients. MPL (p < 0.005) was observed more frequently among Hispanic patients.There was no difference in response to any modality of treatment based on race. Hispanic patients were more likely to undergo allogeneic hematopoietic stem cell transplant 50 (29.9%, p<0.01). Clinical trial participation rates among the groups were similar.The median overall survival (mOS) was 35 months (mo), 31 mo, and 52.5 mo for White, Black and Hispanic patients respectively, p= .01 shown in Figure 1. For very low/low R-IPSS the mOS was 67.6, 52 and 93 mo respectively, p= .028, Figure 2a. For intermediate risk R-IPSS the mOS was 33, 30 and 51 mo respectively, p=0.2, and for high/very high-risk R-IPSS the mOS was 16.8, 21.7, and 25 mo respectively, p=.025. See Figures 2b and 2c. There was no difference in rate of AML transformationConclusions: This large retrospective study revealed racial/ethnic differences in clinical and molecular features of MDS. Hispanic patients had better overall survival. Continued research in this area is recommended to better understand the phenotype and genotype of patients from diverse ethnic/racial backgrounds.Acknowledgement of Funding: NINR Grant # 1K23NR018488-01A [Display omitted] DisclosuresTinsley-Vance: Novartis: Consultancy; Celgene/BMS: Consultancy, Speakers Bureau; Taiho: Consultancy; Fresenius Kabi: Consultancy; Incyte: Consultancy, Speakers Bureau; Astellas: Speakers Bureau; Abbvie: Honoraria; Jazz: Consultancy, Speakers Bureau. Padron: Stemline: Honoraria; Blueprint: Honoraria; Kura: Research Funding; Taiho: Honoraria; Incyte: Research Funding; BMS: Research Funding. Sweet: Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol Meyers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; AROG: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees. Lancet: Celgene/BMS: Consultancy; BerGenBio: Consultancy; AbbVie: Consultancy; Daiichi Sankyo: Consultancy; ElevateBio Management: Consultancy; Millenium Pharma/Takeda: Consultancy; Astellas: Consultancy; Agios: Consultancy; Jazz: Consultancy. Kuykendall: PharmaEssentia: Honoraria; Novartis: Honoraria, Speakers Bureau; Incyte: Consultancy; Prelude: Research Funding; CTI Biopharma: Honoraria; Celgene/BMS: Honoraria, Speakers Bureau; BluePrint Medicines: Honoraria, Speakers Bureau; Abbvie: Honoraria; Protagonist: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding. Sallman: Incyte: Speakers Bureau; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Takeda: Consultancy; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees; Shattuck Labs: Membership on an entity's Board of Directors or advisory committees; Aprea: Membership on an entity's Board of Directors or advisory committees, Research Funding; Syndax: Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Magenta: Consultancy; Intellia: Membership on an entity's Board of Directors or advisory committees; Kite: Membership on an entity's Board of Directors or advisory committees. Komrokji: AbbVie: Consultancy; Geron: Consultancy; BMSCelgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Taiho Oncology: Membership on an entity's Board of Directors or advisory committees; PharmaEssentia: Membership on an entity's Board of Directors or advisory committees; Acceleron: Consultancy; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Speakers Bureau.

Germline DDX41 mutations cause ineffective hematopoiesis and myelodysplasia.

DDX41 mutations are the most common germline alterations in adult myelodysplastic syndromes (MDSs). The majority of affected individuals harbor germline monoallelic frameshift DDX41 mutations and subsequently acquire somatic mutations in their other DDX41 allele, typically missense R525H. Hematopoietic progenitor cells (HPCs) with biallelic frameshift and R525H mutations undergo cell cycle arrest and apoptosis, causing bone marrow failure in mice. Mechanistically, DDX41 is essential for small nucleolar RNA (snoRNA) processing, ribosome assembly, and protein synthesis. Although monoallelic DDX41 mutations do not affect hematopoiesis in young mice, a subset of aged mice develops features of MDS. Biallelic mutations in DDX41 are observed at a low frequency in non-dominant hematopoietic stem cell clones in bone marrow (BM) from individuals with MDS. Mice chimeric for monoallelic DDX41 mutant BM cells and a minor population of biallelic mutant BM cells develop hematopoietic defects at a younger age, suggesting that biallelic DDX41 mutant cells are disease modifying in the context of monoallelic DDX41 mutant BM.