Pathogenesis Of Myelodysplastic Syndromes Research Articles

P730: GENETIC LANDSCAPE OF SOMATIC MYELOID MUTATIONS IN THE PRESENCE OF RARE TERT VARIANTS AND THEIR RELATION WITH MYELOID NEOPLASIA

Background: Genetic variants in TERT, the gene that encodes telomerase reverse transcriptase, can result in accelerated telomere attrition. Impaired telomere maintenance is implicated in the pathogenesis of myelodysplastic syndromes (MDS), with mechanisms remaining to be elucidated. Aims: To explore the clinical and genetic associations of TERT variants in an unselected cohort of patients screened with a myeloid mutation next generation sequencing panel due to clinical suspicion of a myeloid neoplasia. Methods: Using a research protocol approved by the Mayo Clinic Institutional Review Board, we performed a retrospective chart review to identify a cohort of unselected individuals within all historical data at our institution that had undergone somatic mutational analysis for suspected myeloid neoplasia using our insitutional amplicon based next generation sequencing panel (42 genes, including exons 2 to 16 of TERT, with a read depth of at least 250X). TERT variants were classified into those with CADD score >20 and <20 in line with previous literature to identify variants within the top 1% according to their predicted deleteriousness. Additionally, we identified within our cohort individuals that received a diagnosis of MDS, clinical and survival information. Results: We identified 55 different TERT variants (46 missense, 3 in canonical splice sites, 4 synonymous and 2 small inframe deletions) in 148 individuals tested from April of 2016 to November of 2021 (Fig. 1A&B). The five most recurrent variants were c.1234C>T (48 patients), c.1323_1325del (29 patients), c.3164C>T (5 patients), c.604G>A (4 patients) and c.969G>A (4 patients), all with CADD<20. None of these patients were diagnosed with a bona fide telomere biology disorder and no clinical information about telomere length status was available. All variants were considered germline since their allele frequency was near 50%, although no germline confirmation was performed. All variants were clinically classified as uncertain significance according to the American College of Medical Genetics guidelines. Of the 148 total patients, 17 (12%) carried TERT variants with CADD>20 that were distributed thorough all the gene domains with no clustering or presence of hotspots (Fig.1A&B). 59% (10 patients) of CADD>20 variants carriers were diagnosed with MDS: 5 patients with <5% bone marrow blasts (4 with normal karyotype) and 5 patients with 5-19% blasts, all with complex karyotype. This percentage was significantly higher compared to CADD<20 variant carriers (34%, 49 patients, p=0.048 by Chi-square test, Fig. 1C). However, no major differences were found between the two groups in terms of age at diagnosis (median 70 vs 73 years old, p = 0.2305) or AML-free survival (median 10 vs 15.5 months since diagnosis, p=0.4674). Similarly, the percentage of patients presenting additional somatic variants in other myeloid-related genes was similar between CADD<20 and CADD>20 TERT variant carriers (60% vs 64%). The two most frequenly mutated genes in CADD>20 carriers were TP53 (22%), TET2 (18%), RUNX1 (9%), U2AF1 (9%) and BCOR (9%) while in the CADD<20 carriers were TET2 (14%), ASXL1 (11%), SRSF2 (9%), TP53 (7%) and JAK2 (6%). Our data showed that TP53 pathogenic variants were significantly enriched in CADD>20 TERT variant carriers compared to CADD<20 carriers. (22.7% vs 7.4%, p=0.0169, Fig. 1D). Image:Summary/Conclusion: Carriers of TERT variants with CADD score of >20 were more likely to be associated with a diagnosis of MDS and with somatic TP53 mutations in comparison to those with CADD score <20, findings that we plan to validate functionally and prospectively.

P733: DHX9 HELICASE DYSFUNCTION CONTRIBUTES TO DISEASE PROGRESSION IN PATIENTS WITH MYELODYSPLASTIC SYNDROMES

Background:DHX9 is a member of the DEAH (Asp-Glu-Ala-His) helicase family, and participates in regulating DNA replication and RNA processing. DHX9 dysfunction promotes tumorigenesis in several solid cancers. However, the role of DHX9 in myelodysplastic syndromes (MDS) is still unknown. Aims: to investigate the role of DHX9 in the pathogenesis of myelodysplastic syndromes. Methods:DHX9 expression was analyzed in 120 MDS patients and 42 non-MDS benign controls by quantitative PCR. Clinical significance of changes in DHX9 expression was investigated in disease progression and survival. Lentivirus-mediated DHX9 knockdown experiments were performed to investigate its biological function. The mechanistic involvement of DHX9 in MDS development was explored in cell functional assays, gene microarray and pharmacological intervention. Considering the importance of DHX9 in regulation of R-loop, we also investigated the role of DHX9 and R-loop in MDS. Results: We found that overexpression of DHX9 is frequent in MDS patients, and associated with poor survival and high risk of AML transformation. Cell functional assays showed that DHX9 is essential for the maintenance of malignant proliferation of leukemia cells, and knockdown of DHX9 results in increased cell apoptosis and growth inhibition. Gene expression profile and bioinformatics analysis reveal that DHX9 may be involved in PI3K-AKT signaling pathways. Validating experiments show that DHX9 is indispensable for the activation of PI3K-AKT signaling as knockdown of DHX9 inactivates the PI3K-AKT signaling, reduces the expression of anti-apoptosis genes such as CCND2, MYC and BCL2. In addition, we found that DHX9 knockdown leads to R-loop accumulation in MDS cells, and induces R-Loop-dependent DNA damage through ATR-Chk1 activation. It suggests that overexpressed DHX9 could counteract cell growth defect caused by R-Loop which is quite common in MDS patients especially in those with splicing genes mutations. Summary/Conclusion: Our data suggest that DHX9 contributes to disease progression by activation of PI3K-AKT signaling and correcting R-loop-mediated growth defect in MDS, and may serve as a novel prognostic marker for AML transformation and therapeutic target in MDS.

Apoptosis in myelodysplasia: Association with patient age, bone marrow cellularity and karyotypes

Background: Myelodysplastic syndrome (MDS) comprises a heterogeneous group of clonal hematopoietic stem cell diseases, characterized by dysplasias and apoptosis in bone marrow (BM) and cytopenias in peripheral blood. In this study, we analyzed apoptosis in MDS to verify associations with patient age, bone marrow cellularity and karyotypes and to investigate the role of apoptosis in MDS pathogenesis. Methods: Bone marrow cells were collected from 81 patients with primary MDS, of which 60 were adults and 21 children. BM cells were also collected from 10 healthy donors for bone marrow transplants, 5 adults and 5 children, as controls. The patients and controls came from public onco-hematology institutions in Rio de Janeiro. The percentage of apoptotic BM cells was assessed by flow cytometry using two combinations: annexin V-FITC/CD34PE/CD45PerCP and annexin V-FITC/CD14PE/CD45PerCP in BM cells. Cytogenetic analysis was performed by G-banding. Results: The comparison between adult and pediatric patients showed that these patients show a similar behavior with regard to apoptotic cells percentages in BM samples. Apoptosis occurs independently of BM cellularity, being more prominent in patients with hyper/normocellular BM. Patients with normal karyotypes, del(5q), del(17p) had higher apoptosis rates than patients with del(11q) and complex karyotypes. Cells committed to a differentiation program were associated with high rates of apoptosis, suggesting that apoptosis may be a consequence of inefficient hematopoiesis, such that the hematopoietic system may eliminate dysplastic cells at the beginning of the disease. Conclusions: Our results suggest that apoptosis is an important characteristic of BM cells from adult and pediatric MDS patients and may be a consequence of inefficient hematopoiesis. In addition, we suggest that apoptosis is not the main mechanism associated with hypocellular MDS, and it occurs preferentially in MDS cases of hyper/normocellular BM and is associated with a good prognosis. Keywords: Myelodysplastic Syndrome; Apoptosis; Patient age; Bone marrow cellularity; Karyotypes.

Miyelodisplastik sendrom hastalığında P53 polimorfizmlerinin önemi

Amaç: Miyelodisplastik sendrom (MDS) akut miyeloid lösemiye dönüşüm riski yüksek olan, artmış apoptozis ve azalmış hematopoez oranlarıyla karakterize klonal bir hastalıktır. MDS patogenezi tam olarak açıklanabilmiş değildir. Olguların ~%50' si anormal karyotiptedir ve bu oran ikincil MDS' de %80 civarındadır. P53 proteini kök hücre homeostazının önemli düzenleyicisidir ve hücre döngüsünün düzenlenmesi, apoptotik ile enflamatuar yanıt gibi bir dizi hücresel olayda yer alır. Genomik bütünlüğün korunmasında da önemli görevleri bulunan TP53 geni kanserlerde sıklıkla mutasyona uğramaktadır; ancak, mutasyonlarının yanında bazı gen polimorfizmlerinin de kanserle ilişkili oldukları bilinmektedir. Çalışmadaki amacımız, dört yaygın p53 tek nükleotid polimorfizminin MDS’ deki yaygınlıklarını ve hastalık gelişimi üzerine etkilerini belirlemektir. Bu amaçla, Ege Üniversitesi Tıp Fakültesi Dahiliye Anabilim Dalı Hematoloji Bilim Dalı' nda MDS tanısı ile takip edilen ya da yeni tanı almış 100 olgu çalışmaya dahil edildi. Gereç ve Yöntem: MDS’li olguların periferik kan lökositlerinden izole edilen DNA’lar gerçek-zamanlı PCR yöntemiyle çalışılarak, p53 polimorfizmleri (rs35163653, rs35993958, rs1800371, rs1042522) uygun probların kullanımıyla ve erime eğrisi analizleriyle belirlendi. Bulgular: İncelenen dört yaygın p53 polimorfizmin arasında özellikle rs1042522 polimorfizmindeki atasal olmayan G alelinin MDS’li olgularda artmış olduğu gözlenmiştir (C:%30.3; G:%69.7). Fonksiyonel olduğu, yani sentez edilen proteinin fonksiyonunu etkilediği bilinen bu polimorfizmde 417. pozisyonundaki C nukleotidinin G’ye transisyonu (C&amp;gt;G), proteinin 72. pozisyonundaki prolin amino asidinin arjinine (P72R) kodlanmasına yol açmaktadır. Sonuç: Çalışmamız, MDS hastalık grubunda rs35163653, rs35993958, rs1800371 ve rs1042522 p53 polimorfizmlerinin araştırıldığı ilk çalışmadır. Bunlardan, rs1042522 polimorfizminin kansere yatkınlık ve duyarlılıkla ilişkili olduğu yapılan diğer bazı çalışmalarla gösterilmiş olması nedeniyle, MDS hastalığı için de yüksek risk oluşturabileceği düşünülmektedir. Sonuç olarak, MDS hastalığı için gerçekleştirilen bu çalışmanın daha geniş bir olgu grubuyla tekrarlanmasıyla rs1042522 polimorfizmi ileride MDS teşhisinde belirteç olarak kullanılabilecektir.

Bioinformatics Analysis of Core Genes and Key Pathways in Myelodysplastic Syndrome

To screen differentially expressed gene (DEG) related to myelodysplastic syndrome (MDS) based on Gene Expression Omnibus (GEO) database, and explore the core genes and pathogenesis of MDS by analyzing the biological functions and related signaling pathways of DEG. The expression profiles of GSE4619, GSE19429, GSE58831 including MDS patients and normal controls were downloaded from GEO database. The gene expression analysis tool (GEO2R) of GEO database was used to screen DEG according to | log FC (fold change) |≥1 and P<0.01. David online database was used to annotate gene ontology function (GO). Metascape online database was used to enrich and analyze differential genes in Kyoto Encyclopedia of Genes and Genomes (KEGG). The protein-protein interaction network (PPI) was constructed by using STRING database. CytoHubba and Mcode plug-ins of Cytoscape were used to analyze the key gene clusters and hub genes. R language was used to diagnose hub genes and draw the ROC curve. GSEA enrichment analysis was performed on GSE19429 according to the expression of LEF1. A total of 74 co-DEG were identified, including 14 up-regulated genes and 60 down regulated genes. GO enrichment analysis indicated that BP of down regulated genes was mainly enriched in the transcription and regulation of RNA polymerase II promoter, negative regulation of cell proliferation, and immune response. CC of down regulated genes was mainly enriched in the nucleus, transcription factor complexes, and adhesion spots. MF was mainly enriched in protein binding, DNA binding, and β-catenin binding. KEGG pathway was enriched in primary immunodeficiency, Hippo signaling pathway, cAMP signaling pathway, transcriptional mis-regulation in cancer and hematopoietic cell lineage. BP of up-regulated genes was mainly enriched in type I interferon signaling pathway and viral response. CC was mainly enriched in cytoplasm. MF was mainly enriched in RNA binding. Ten hub genes and three important gene clusters were screened by STRING database and Cytoscape software. The functions of the three key gene clusters were closely related to immune regulation. ROC analysis showed that the hub genes had a good diagnostic significance for MDS. GSEA analysis indicated that LEF1 may affect the normal function of hematopoietic stem cells by regulating inflammatory reaction, which further revealed the pathogenesis of MDS. Bioinformatics can effectively screen the core genes and key signaling pathways of MDS, which provides a new strategy for the diagnosis and treatment of MDS.

Relationship of HIF‑1α expression with apoptosis and cell cycle in bone marrow mesenchymal stem cells from patients with myelodysplastic syndrome.

Myelodysplastic syndrome (MDS) is a group of abnormal clonal disorders with ineffective hematopoiesis, which are incurable with conventional therapy. Of note, MDS features an abnormal bone marrow microenvironment, which is related to its incidence. The hypoxia-inducible factor-1α (HIF-1α) transcriptional signature is generally activated in bone marrow stem/progenitor cells of patients with MDS. To analyze the expression of HIF-1α in bone marrow mesenchymal stem cells (BM-MSCs) and the apoptosis and cell cycle features associated with the disease, BM-MSCs were obtained from 40 patients with a definitive diagnosis of MDS and 20 subjects with hemocytopenia but a negative diagnosis of MDS as a control group. Reverse transcription-quantitative PCR and western blot analyses were used to measure HIF-1α expression in cells from the two groups and apoptosis and cell cycle were also analyzed and compared between the groups using flow cytometry assays. BM-MSCs from both the control group and the MDS group exhibited a fibroblast-like morphology, had similar growth cycles and were difficult to passage stably. It was observed that BM-MSCs from the MDS group had significantly higher HIF-1α expression levels than the control group (P<0.05). Furthermore, the BM-MSCs from the MDS group had a higher proportion of cells in early apoptosis (5.22±1.34 vs. 2.04±0.08%; P<0.0001) and late apoptosis (3.38±0.43 vs. 1.23±0.11%; P<0.01) and exhibited cell cycle arrest. This may be a noteworthy aspect of the pathogenesis of MDS and may be related to high HIF-1α expression under a hypoxic state in the bone marrow microenvironment. Furthermore, the expression of HIF-1α in bone marrow tissue sections from patients with MDS in the International Prognostic Scoring System (IPSS) lower-risk group was higher than that from patients with MDS in the IPSS high-risk group. These results revealed the role of HIF-1α as a central pathobiology mediator of MDS and an effective therapeutic target for a broad spectrum of patients with MDS, particularly for patients in the lower-risk group.

Pathophysiologic and clinical implications of molecular profiles resultant from deletion 5q.

SummaryBackgroundHaploinsufficiency (HI) resulting from deletion of the long arm of chromosome 5 [del(5q)] and the accompanied loss of heterozygosity are likely key pathogenic factors in del(5q) myeloid neoplasia (MN) although the consequences of del(5q) have not been yet clarified.MethodsHere, we explored mutations, gene expression and clinical phenotypes of 388 del(5q) vs. 841 diploid cases with MN [82% myelodysplastic syndromes (MDS)].FindingsDel(5q) resulted as founder (better prognosis) or secondary hit (preceded by TP53 mutations). Using Bayesian prediction analyses on 57 HI marker genes we established the minimal del(5q) gene signature that distinguishes del(5q) from diploid cases. Clusters of diploid cases mimicking the del(5q) signature support the overall importance of del(5q) genes in the pathogenesis of MDS in general. Sub-clusters within del(5q) patients pointed towards the inherent intrapatient heterogeneity of HI genes.InterpretationThe underlying clonal expansion drive results from a balance between the “HI-driver” genes (e.g., CSNK1A1, CTNNA1, TCERG1) and the proapoptotic “HI-anti-drivers” (e.g., RPS14, PURA, SIL1). The residual essential clonal expansion drive allows for selection of accelerator mutations such as TP53 (denominating poor) and CSNK1A1 mutations (with a better prognosis) which overcome pro-apoptotic genes (e.g., p21, BAD, BAX), resulting in a clonal expansion. In summary, we describe the complete picture of del(5q) MN identifying the crucial genes, gene clusters and clonal hierarchy dictating the clinical course of del(5q) patients.FundingTorsten Haferlach Leukemia Diagnostics Foundation. US National Institute of Health (NIH) grants R35 HL135795, R01HL123904, R01 HL118281, R01 HL128425, R01 HL132071, and a grant from Edward P. Evans Foundation.

Gut Microbiome and Plasma Metabolomic Analysis in Patients with Myelodysplastic Syndrome.

Myelodysplastic syndrome (MDS) is a heterogeneous group of clonal hematopoietic stem cell disorders. Studies have shown the involvement of an abnormal immune system in MDS pathogenesis. The gut microbiota are known to influence host immunity and metabolism, thereby contributing to the development of hematopoietic diseases. In this study, we performed gut microbiome and plasma metabolomic analyses in patients with MDS and healthy controls. We found that patients with MDS had a different gut microbial composition compared to controls. The gut microbiota in MDS patients showed a continuous evolutionary relationship from the phylum to the species level. At the species level, the abundance of Haemophilus parainfluenzae, Streptococcus luteciae, Clostridium citroniae, and Gemmiger formicilis increased, while that of Prevotella copri decreased in MDS patients compared to controls. Moreover, abundance of bacterial genera correlated with the percentage of lymphocyte subsets in patients with MDS. Metabolomic analysis showed that the concentrations of hypoxanthine and pyroglutamic acid were increased, while that of 3a,7a-dihydroxy-5b-cholestan was decreased in MDS patients compared to controls. In conclusion, gut microbiome and plasma metabolomics are altered in patients with MDS, which may be involved in the immunopathogenesis of the disease.

Inflammatory Cytokine Profiles Do Not Differ Between Patients With Idiopathic Cytopenias of Undetermined Significance and Myelodysplastic Syndromes.

Immune dysregulation has been highlighted as a key player in the pathogenesis of myelodysplastic syndromes (MDS), but little is known about cytokine profiles in patients with unexplained cytopenia with or without mutations in MDS-associated genes (clonal cytopenias of undetermined significance [CCUS] and idiopathic cytopenias of undetermined significance [ICUS], respectively), which often precede MDS. Here, we study the cytokine profiles in 111 patients with ICUS (N = 41), CCUS (N = 30), lower-risk MDS (LR-MDS; N = 22) and higher-risk MDS (HR-MDS; N = 18), and in healthy elderly controls (N = 21). Twenty cytokines were examined in blood plasma at time of diagnosis using Luminex assays and enzyme linked immunosorbent assays. The cytokine levels were compared between patient groups, and in patients versus controls. Associations between cytokines and MDS-associated mutations were evaluated. An aberrant cytokine profile was observed in all patient groups relative to healthy elderly controls. Patients had significantly higher levels of IL-6 (P< 0 .001), tumor necrosis factor α (P < 0.001), IL-10 (P < 0.001), and C-X-C motif chemokine 10 (P < 0.001) and lower levels of transforming growth factor beta 1 (P < 0.001), CCL5/regulated on activation normal T-cell expressed and secreted (P < 0.001), and S100A4 (P < 0.001) compared with healthy controls. Survival was significantly shorter in CCUS and MDS patients with a high systemic inflammatory cytokine load (median overall survival [OS] 21 months) compared with those with low-moderate systemic inflammatory cytokine load (median OS 64 months; P < 0.0001). These data suggest that patients with ICUS and CCUS have cytokine levels as abnormal as in LR-MDS. Indeed, high cytokine levels are present before MDS is diagnosed and cytokine levels are elevated irrespective of the presence or size of the myeloid clones. Cytokines may have a prognostic impact at a very early premalignant stage of myeloid disorders.

Efficacy and Safety of Hypomethylating Agents in Chronic Myelomonocytic Leukemia: A Single-Arm Meta-analysis.

Background Chronic myelomonocytic leukemia (CMML) is a myeloid neoplasm with features of the myelodysplastic syndromes (MDSs) and myeloproliferative neoplasm presenting with peripheral blood monocytosis and an inherent risk for transformation to acute myeloid leukemia, while the abnormal DNA methylation plays a critical role in the pathogenesis of MDS, which is a disease of disordered differentiation. Recently, with the rapid development of molecular biology, hypomethylating agents (HMAs) for the treatment of MDS has gradually become a research focus. The objective of this study was to evaluate the benefits and risks of HMAs for patients with CMML. Materials and Methods PubMed, Embase, the Cochrane Library, and three Chinese databases were searched for studies published before November 2020 that used HMAs in CMML. Results The pooled objective response rate (ORR), complete response (CR), and partial response (PR) were 50.0, 21.0, and 2.0%, respectively. The proportion of patients with minor response (MR) was significantly higher for decitabine (DAC) than for azacitidine (AZA). There was no significant difference in hematologic improvement, ORR, CR, and PR rates between the DAC and AZA groups. Hematological toxicity included neutropenia grade 3/4 (14.0%), anemia grade 3/4 (17.0%), and thrombocytopenia grade 3/4 (22.0%). Conclusion This study showed that HMAs were effective and safe in the treatment of CMML, but large multicenter study would be needed to confirm the efficacy of HMAs for the treatment of CMML with different risk level and genetic abnormality, to support individualization treatment theoretically.

Toll-like receptor and cytokine expression throughout the bone marrow differs between patients with low- and high-risk myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders, the pathogenesis of which involves enhanced immune signaling that promotes or selects for mutant hematopoietic stem and progenitor cells (HSPCs). In particular, toll-like receptor (TLR) expression and signaling are enhanced in MDS, and their inhibition is an attractive therapeutic strategy. Although prior studies have reported increased expression of TLR2 and its binding partners TLR1 and TLR6 in the CD34+ cells of patients with MDS (especially those with low-risk disease), TLR expression in other cell types throughout the bone marrow is largely unknown. To address this, we used mass cytometry to assess the expression of TLR1, TLR2, and TLR6 and cytokines in the bone marrow hematopoietic cells of six low/intermediate-risk and six high-risk unmatched MDS bone marrow samples, as well as healthy controls, both at baseline and in response to TLR agonists. We observed several consistent differences between the groups. Most notably, TLR expression was upregulated in multiple cell populations in the low/intermediate-risk, but not high-risk, patients. In addition, many cytokines, including interleukin-6, interleukin-8, tumor necrosis factor α, transforming growth factor β, macrophage inflammatory protein 1β, and granzyme B, were highly expressed from various cell types in low/intermediate-risk patients. However, these same cytokines, with the exception of transforming growth factor β, were expressed at lower levels in high-risk MDS. Together, these findings highlight the differential role of inflammation, and specifically TLR expression, in low/intermediate- versus high-risk MDS, and suggest that elevated TLR expression and cytokine production in multiple cell types likely influences the pathogenesis of MDS in lower-risk patients.

Role of p53 in regulation of hematopoiesis in health and disease.

Human aging is associated with an exponential increase in the occurrence of clonal hematopoiesis of indeterminate potential (CHIP). CHIP is associated with increased risks of de novo and therapy-related hematologic neoplasms and serves as a reservoir for leukemic relapse. Somatic mutations in the TP53 gene, which encodes the tumor suppressor protein p53, rank in the top five among genes that were mutated in CHIP. TP53 mutations in CHIP are associated with an increased incidence of myeloid neoplasms such as myelodysplastic syndromes (MDS) and acute myeloid leukemia (AML). This review focuses on mechanisms by which mutant p53 promotes CHIP progression and drives the pathogenesis of MDS and AML. We will also discuss potential therapeutic approaches that can target mutant p53 and improve treatment outcomes of MDS and AML. TP53 was frequently mutated in individuals with CHIP as well as in patients with MDS and AML. While clinical studies suggest that p53 mutant hematopoietic stem and progenitor cell expansion may predispose the elderly to hematologic neoplasms, the underlying mechanisms are not fully understood. Recent findings suggest that mutant p53 may utilize both cell autonomous and noncell autonomous mechanisms to promote CHIP development. Furthermore, we and others have demonstrated that several gain-of-function mutant p53 proteins have enhanced oncogenic potential beyond dominant-negative and loss-of-function effects. Notably, TP53 allelic state has important implications for genome stability, clinical presentation, and outcomes in MDS. Some small molecules reactivating wild-type p53 tumor suppressor activity show promising effects on some human MDS and AML cells with TP53 mutations in preclinical and early phases of clinical studies. TP53 mutations in MDS and AML are correlated with advanced disease, poor prognosis, reduced overall survival, and dismal outcomes. Deep understanding of the functions of mutant p53 proteins is essential to devise effective therapies for patients with myeloid neoplasms and other human cancers with TP53 mutations. Targeting mutant p53 directly or pathways regulated by mutant p53 holds great potential in preventing CHIP progression and treating MDS and AML patients with TP53 mutations.

Immunodepletion of MDSC by AMV564, a novel bivalent, bispecific CD33/CD3 T cell engager, ex vivo in MDS and melanoma

We have reported previously that CD33hi myeloid-derived suppressor cells (MDSCs) play a direct role in the pathogenesis of myelodysplastic syndromes (MDSs) and that their sustained activation contributes to hematopoietic and immune impairment, including modulation of PD1/PDL1. MDSCs can also limit the clinical activity of immune checkpoint inhibition in solid malignancies. We hypothesized that depletion of MDSCs may ameliorate resistance to checkpoint inhibitors and, hence, targeted them with AMV564 combined with anti-PD1 in MDS bone marrow (BM) mononuclear cells (MNCs) enhanced activation of cytotoxic Tcells. AMV564 was active invivo in a leukemia xenograft model when co-administered with healthy donor peripheral blood MNCs (PBMCs). Our findings provide a strong rationale for clinical investigation of AMV564 as a single agent or in combination with an anti-PD1 antibody and in particular for treatment of cancers resistant to checkpoint inhibitors.

Dysregulation of immune cell and cytokine signalling correlates with clinical outcomes in myelodysplastic syndrome (MDS).

Myelodysplastic syndromes (MDS) are characterised by ineffective haematopoiesis. Although hypomethylating agents (HMA) have improved survival in higher-risk MDS, most patients eventually succumb to progressive disease. Utilising samples collected prospectively from three MDS clinical trials, we analysed genetic and immunological biomarkers and correlated them with clinical outcomes. A hundred and fifty four samples were analysed from 133 de novo MDS patients for T-cell and myeloid cell immunophenotyping and gene expression analysis. Treatments were with HMA or immunomodulatory drug (IMiD) alone or in combination. We observed differences in immune cell subsets between lower- and higher-risk IPSS groups with NKT cells, MDSCs, intermediate-proinflammatory and non-classical monocytes being higher in the latter group, while naïve CD4+ T cells were reduced. Intermediate-proinflammatory monocytes were increased in non-responders and those failing to achieve at least a haematological improvement. Proinflammatory NKT cells were increased at diagnosis for patients failing to derive clinical benefit after 12months of treatment. Gene expression analysis of paired bone marrow (BM) colony-forming units (CFUs) from diagnosis and 4 cycles post-treatment confirmed that genes involved in cytokine signalling were downregulated in C4 normal colonies. These findings support the central roles of dysregulation in innate immunity and inflammatory signalling in the pathogenesis of MDS which correlated with clinical outcomes post-treatment.

Effect of Decitabine on Regulatory T Cells Relative Content in Peripheral Blood and Bone Marrow of Patients with Myelodysplastic Syndrome/Acute Myeloid Leukemia

To investigate regulatory T cells (Tregs) relative content in peripheral blood and bone marrow of patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) treated with or without decitabine (DAC), analyze the immunomodulatory of Tregs in pathogenesis and remission of MDS and AML, as well as effect of DAC on Tregs. From October 2018 to February 2019, 15 patients with MDS and 49 patients with AML (newly diagnosed, treated with DAC or other chemotherapy regimens) were enrolled in this study, and 14 cases with iron deficiency or megaloblastic anemia while without malignant tumor and autoimmune disease as controls. The Tregs relative contents in bone marrow and peripheral blood were analyzed by flow cytometry, meanwhile clinical data of the objects were collected. In peripheral blood and bone marrow of the patients with MDS and AML, the Tregs relative contents at newly diagnosed were higher than those of the control group (P=0.05, P=0.043). The Tregs relative content of AML patients in DAC regimen treatment group was significantly lower than that in the newly diagnosed group and non-DAC chemotherapy group (P<0.05). In DAC regimen treatment group, the Tregs relative contents was significantly lower in remission group than in non-remission group (P<0.05). There was no difference between DAC regimen treatment group and control group in Tregs relative content. DAC may increase the body's anti-tumor immunity by consuming Tregs content, enhance the body's immune function to identify and kill tumor cells, thereby promote the patients' reliefs.

Identification of a novel HOOK3-FGFR1 fusion gene involved in activation of the NF-kappaB pathway

BackgroundRearrangements involving the fibroblast growth factor receptor 1 (FGFR1) gene result in 8p11 myeloproliferative syndrome (EMS), which is a rare and aggressive hematological malignancy that is often initially diagnosed as myelodysplastic syndrome (MDS). Clinical outcomes are typically poor due to relative resistance to tyrosine kinase inhibitors (TKIs) and rapid transformation to acute leukemia. Deciphering the transcriptomic signature of FGFR1 fusions may open new treatment strategies for FGFR1 rearrangement patients.MethodsDNA sequencing (DNA-seq) was performed for 20 MDS patients and whole exome sequencing (WES) was performed for one HOOK3-FGFR1 fusion positive patient. RNA sequencing (RNA-seq) was performed for 20 MDS patients and 8 healthy donors. Fusion genes were detected using the STAR-Fusion tool. Fluorescence in situ hybridization (FISH), quantitative real-time PCR (qRT-PCR), and Sanger sequencing were used to confirm the HOOK3-FGFR1 fusion gene. The phosphorylation antibody array was performed to validate the activation of nuclear factor-kappaB (NF-kappaB) signaling.ResultsWe identified frequently recurrent mutations of ASXL1 and U2AF1 in the MDS cohort, which is consistent with previous reports. We also identified a novel in-frame HOOK3-FGFR1 fusion gene in one MDS case with abnormal monoclonal B-cell lymphocytosis and ring chromosome 8. FISH analysis detected the FGFR1 break-apart signal in myeloid blasts only. qRT-PCR and Sanger sequencing confirmed the HOOK3-FGFR1 fusion transcript with breakpoints located at the 11th exon of HOOK3 and 10th exon of FGFR1, and Western blot detected the chimeric HOOK3-FGFR1 fusion protein that is presumed to retain the entire tyrosine kinase domain of FGFR1. The transcriptional feature of HOOK3-FGFR1 fusion was characterized by the significant enrichment of the NF-kappaB pathway by comparing the expression profiling of FGFR1 fusion positive MDS with 8 healthy donors and FGFR1 fusion negative MDS patients. Further validation by phosphorylation antibody array also showed NF-kappaB activation, as evidenced by increased phosphorylation of p65 (Ser 536) and of IKBalpha (Ser 32).ConclusionsThe HOOK3-FGFR1 fusion gene may contribute to the pathogenesis of MDS and activate the NF-kappaB pathway. These findings highlight a potential novel approach for combination therapy for FGFR1 rearrangement patients.

Patient-specific MDS-RS iPSCs define the mis-spliced transcript repertoire and chromatin landscape of SF3B1-mutant HSPCs

AbstractSF3B1K700E is the most frequent mutation in myelodysplastic syndrome (MDS), but the mechanisms by which it drives MDS pathogenesis remain unclear. We derived a panel of 18 genetically matched SF3B1K700E- and SF3B1WT-induced pluripotent stem cell (iPSC) lines from patients with MDS with ring sideroblasts (MDS-RS) harboring isolated SF3B1K700E mutations and performed RNA and ATAC sequencing in purified CD34+/CD45+ hematopoietic stem/progenitor cells (HSPCs) derived from them. We developed a novel computational framework integrating splicing with transcript usage and gene expression analyses and derived a SF3B1K700E splicing signature consisting of 59 splicing events linked to 34 genes, which associates with the SF3B1 mutational status of primary MDS patient cells. The chromatin landscape of SF3B1K700E HSPCs showed increased priming toward the megakaryocyte- erythroid lineage. Transcription factor motifs enriched in chromatin regions more accessible in SF3B1K700E cells included, unexpectedly, motifs of the TEA domain (TEAD) transcription factor family. TEAD expression and transcriptional activity were upregulated in SF3B1-mutant iPSC-HSPCs, in support of a Hippo pathway-independent role of TEAD as a potential novel transcriptional regulator of SF3B1K700E cells. This study provides a comprehensive characterization of the transcriptional and chromatin landscape of SF3B1K700E HSPCs and nominates novel mis-spliced genes and transcriptional programs with putative roles in MDS-RS disease biology.

Radiation-induced hematopoietic disorders

Hematopoietic stem cells are one of the most sensitive tissues to radiation exposure. Epidemiological studies of atomic bomb survivors in Nagasaki and Hiroshima revealed a radiation dose-response relationship for acute myeloid leukemia, acute lymphoblastic leukemia, and Chronic myelogenous leukemia. In our study of myelodysplastic syndrome (MDS) in Nagasaki, the relative risk was higher in the proximal-exposed group. Additionally, the frequency of chromosome abnormalities associated with poor prognosis was higher in the proximal-exposed group than in the non-exposed group. However, no association between the exposure distance and prognosis was observed. We used next-generation sequencing to analyze the role of genetic abnormalities in the development of MDS. The results indicated that genetic mutations related to DNA methylation pathways, which are frequently observed in de novo MDS, were considerably less frequent in the proximal-exposed than in the distal-exposed group. These results suggest that the pathogenesis of MDS in atomic bomb survivors may be different from that of treatment-related and de novo MDS.

The Role of BAALC-Expressing Leukemia Precursor Cells in the Pathogenesis of Myelodysplastic Syndromes

The present paper provides evidence for a high detection rate of BAALC gene overexpression, also combined with WT1 gene overexpression, in patients with myelodysplastic syndromes (MDS) and FISH-verified chromosome defects. The BAALC and WT1 gene expression profiling of 16 MDS patients (6 out of them received allogeneic hematopoietic stem cell transplantation) showed an increased BAALC expression in 14 patients. The expression level in 2 patients was near the cut-off. Low expression levels were identified in a female patient with isolated 5q deletion in karyotype and also with its combination with complex karyotype. On the other hand, the highest expression levels were reported in patients with normal karyotype and 3q26 locus rearrangement, which was associated with EVI1 gene overexpression. Since the BAALC expression level, at least in patients with the major (except for М3 and М7) FAB-variants of acute myeloid leukemias (AML), was closely associated with BAALC-producing precursor cells of leukemia clone, a profound study of this phenomenon in MDS patients seems to be important for understanding the finest mechanisms underlying the pathogenesis of AML and AML relapses on the level of precursor cells.

Hematopoietic Stem Cells (HSC) and Granulocyte Macrophage Progenitors (GMP) are the Oxidative Stress Targets in Low/Intermediate-1 Risk Myelodysplastic Syndromes.

Myelodysplastic Syndromes (MDS) are a heterogenous group of clonal hematopoietic stem cell malignancies. Previous studies showed that Reactive Oxygen Species (ROS) play a role in the pathogenesis and clinical evolution of MDS, contributing to Hematopoietic Stem and Progenitor Cells (HSPC) genetic instability. Less is known about ROS levels in the various sub-populations of MDS HSPC and how they correlate with clinical data in MDS patients. Our study aims to analyze ROS levels in MDS Hematopoietic Stem Cells (HSC), common myeloid progenitors (CMP), Granulocyte Macrophages Progenitors (GMP) and megakaryocyte-erythrocyte progenitors (MEP); afterwards, we looked at the relationship between ROS levels and clinical data. thirty-eight MDS and 27 Normal Bone Marrow (NBM) samples were collected; ROS levels were analyzed via multicolor flow cytometry. In both NBM and MDS, HSC showed much higher ROS levels than progenitors (3 to 4 folds, p < 0.0001); HSC ROS were significantly more elevated in MDS-no excess blasts versus MDS with excess blasts and versus NBM. GMP from MDS-no excess blasts showed higher ROS compared to NBM GMP. The 3 MDS with Ringed Sideroblasts (RS) showed more elevated ROS in HSC and GMP compared to the not RS low/intermediate-1 MDS; the 2 monosomy 7 patients displayed higher ROS levels in each subpopulation compared to the normal karyotype MDS; the only del(5q) patient did not show relevant differences in ROS levels compared to the median of the normal karyotype MDS ROS. The 9 high transfusion burden patients exhibited higher ROS in HSC and GMP compared to NBM HSC and GMP. These data were not confirmed in low transfusion burden (n:2) and non-transfused patients (n:26). In low/intermediate-1 MDS, a direct correlation between ferritin values and ROS levels in progenitors, but not in HSC, was detected. Interestingly, low/intermediate-1 risk patients that are no longer responding to recombinant human erythropoietin (rh-EPO) showed higher ROS levels in GMP and HSC. Our data showed that ROS can play a role in the pathogenesis and maintenance of low and intermediate-1 risk MDS clone; ROS status can be influenced by several clinical factors as ferritin levels and rh-EPO treatment. In this scenario, high ROS levels can contribute to genetic instability and influence progression to AML. Further biological studies are needed to elucidate ROS role in MDS pathogenesis and analyze the possible benefit of antioxidant drugs added to the standard MDS treatments.