Pathogenesis Of Myelodysplastic Syndromes Research Articles

Pathogenesis and inflammaging in myelodysplastic syndrome.

Myelodysplastic syndromes (MDS) are a genetically complex and phenotypically diverse set of clonal hematologic neoplasms that occur with increasing frequency with age. MDS has long been associated with systemic inflammatory conditions and disordered inflammatory signaling is implicated in MDS pathogenesis. A rise in sterile inflammation occurs with ageing and the term "inflammaging" has been coined by to describe this phenomenon. This distinct form of sterile inflammation has an unknown role in in the pathogenesis of myeloid malignancies despite shared correlations with age and ageing-related diseases. More recent is a discovery that many cases of MDS arise from clonal hematopoiesis of indeterminate potential (CHIP), an age associated, asymptomatic pre-disease state. The interrelationship between ageing, inflammation and clonal CHIP is complex and likely bidirectional with causality between inflammaging and CHIP potentially instrumental to understanding MDS pathogenesis. Here we review the concept of inflammaging and MDS pathogenesis and explore their causal relationship by introducing a novel framing mechanism of "pre-clonal inflammaging" and "clonal inflammaging". We aim to harmonize research on ageing, inflammation and MDS pathogenesis by contextualizing the current understanding of inflammaging and the ageing hematopoietic system with what is known about the etiology of MDS via its progression from CHIP.

Pediatric Myelodysplastic Syndrome.

Myelodysplastic syndromes (MDSs) are rare in children and have unique clinical manifestations and implications. To review the clinical features, pathogenesis, and classification of pediatric MDS. Published literature and personal experience. Pediatric MDS vastly differs from adult MDS. Evaluation for the presence of an underlying germline predisposition syndrome is critical for optimal classification and management. Because of the rarity of cases, resources to aid with the recognition, diagnosis, and management of pediatric MDS are limited, and multi-institutional collaborative studies are needed for the future.

Iron overload impact on peripheral blood cells, lymphocytes and karyotypes in newly diagnosed myelodysplastic syndromes (MDS) patients: a single-center retrospective analysis

We conducted a retrospective analysis of 68 newly diagnosed myelodysplastic syndrome (MDS) patients who were treated in the Department of Hematology at Yuncheng Central Hospital affiliated to Shanxi Medical University from October 2017 to March 2022. Based on the serum ferritin (SF) level, the newly diagnosed MDS patients were divided into two groups: iron overload (IOL) group (SF > 1000 ng/mL) and non-iron overload (NIOL) group(SF ≤ 1000 ng/mL). General clinical data, peripheral blood cells, lymphocyte subsets and marrow karyotypes were compared. We found that MDS patients with IOL had lower hemoglobin (Hb), lower reticulocyte (RET) counts, and lower absolute natural killer (NK) cell counts compared with NIOL group (p < 0.05). The correlation analysis also showed a negative correlation between the NK cell counts and SF level (r = −0.270, P = 0.026). Furthermore, we found IOL group had higher incidence of complex and poor karyotypes. In conclusion, we found that IOL is correlated with anemia in MDS patients, which may lead to a decrease in T lymphocyte cells, especially in NK cells, that play a role in the immune pathogenesis of MDS, thereby suppressing immune surveillance function. Additionally, IOL may contribute to the pathogenesis of MDS by affecting karyotypes.

Inflammation in myelodysplastic syndrome pathogenesis

Inflammation is a key driver of the progression of preleukemic myeloid conditions, such as clonal hematopoiesis of indeterminate potential (CHIP) and clonal cytopenia of undetermined significance (CCUS), to myelodysplastic syndromes (MDS). Inflammation is a critical mediator in the complex interplay of the genetic, epigenetic, and microenvironmental factors contributing to clonal evolution. Under inflammatory conditions, somatic mutations in TET2, DNMT3A, and ASXL1, the most frequently mutated genes in CHIP and CCUS, induce a competitive advantage to hematopoietic stem and progenitor cells, which leads to their clonal expansion in the bone marrow. Chronic inflammation also drives metabolic reprogramming and immune system deregulation, further promoting the expansion of malignant clones. This review underscores the urgent need to fully elucidate the role of inflammation in MDS initiation and highlights the potential of the therapeutical targeting of inflammatory pathways as an early intervention in MDS.

Understanding MDS stem cells: Advances and limitations

In work spanning several decades, extensive studies have focused on the properties of malignant stem cells that drive the pathogenesis of acute myeloid leukemia (AML). However, relatively little attention has been devoted to several serious myeloid malignancies that occur prior to the onset of frank leukemia, including myelodysplastic syndrome (MDS). Like leukemia, MDS is hypothesized to arise from a pool of immature malignant stem and progenitor cells (MDS-SCs) that serve as a reservoir for disease evolution and progression1. While multiple studies have sought to identify and characterize the biology and vulnerabilities of MDS-SCs, yet translation of scientific concepts to therapeutically impactful regimens has been limited. Here, we evaluate the currently known properties of MDS-SCs as well as the post-transcriptional mechanisms that drive MDS pathogenesis at a stem and progenitor level. We highlight limits and gaps in our characterization and understanding of MDS-SCs and address the extent to which the properties of MDS-SC are (and can be) inferred from the characterization of LSCs.

Spontaneous Splenic Rupture in a Patient with Myelodysplastic Syndrome

Introduction: Myelodysplastic syndrome (MDS) is a clonal hematopoietic disorder with a risk of progression to acute myeloid leukaemia. This case report discusses a rare instance of spontaneous splenic rupture in a patient with MDS. Case Report: A 76-year-old male with a history of MDS presented with acute abdominal pain and was found to have a splenic rupture. Despite declining chemotherapy, the patient underwent an emergency splenectomy after a CT scan revealed hemoperitoneum. Post-surgery, the patient experienced hypovolemic shock, necessitating a second operation. Discussion: Splenic rupture in MDS is uncommon and its pathogenesis is not fully understood. Management of MDS is complex, often requiring a multidisciplinary approach. This case emphasizes the importance of considering patient preferences in treatment decisions and highlights the role of next-generation sequencing in understanding MDS pathogenesis. Conclusion: The case underscores the need for vigilance in managing MDS due to potential complications like splenic rupture. It also illustrates the importance of personalized care and advances in genetic profiling in predicting prognosis and guiding treatment in MDS.

Hypermethylation of GSTM5 and its effect on oxidation in myelodysplastic syndrome

AbstractBackgroundHypermethylation of glutathione‐S‐transferase 5 (GSTM5) and its effect on oxidation in the pathogenesis of myelodysplastic syndrome (MDS) were investigated.MethodsGSTM5 methylation was detected in bone marrow (BM) samples from MDS patients, acute myeloid leukemia (AML) patients, and control individuals using methylation‐specific PCR and MassARRAY analysis. Bisulfite sequencing PCR was performed to verify methylation levels, while mRNA levels were determined using reverse transcription polymerase chain reaction. Correlations between GSTM5 methylation and clinical parameters were analyzed. The MDS cell line, SKM‐1, was treated with decitabine, buthionine sulfoximine, or overexpression of GSTM5, and the glutathione level and cell viability were detected.ResultsThe MassARRAY analysis revealed significant differences in GSTM5 methylation levels between the MDS and control groups. GSTM5 methylation levels were significantly increased in the high‐risk subgroup and showed a significant association with MDS progression to AML (hazard ratio = 3.6). Levels of GSTM5 mRNA were significantly decreased in the MDS group, exhibiting a negative correlation with the GSTM5 gene methylation level. Normal BM HS‐5 cells exhibited significantly lower levels of GSTM5 methylation than SKM‐1 cells. Overexpression of GSTM5 in SKM‐1 cells or treatment with buthionine sulfoximine or decitabine resulted in inhibition of proliferation and significantly decreased glutathione levels.ConclusionsGSTM5 plays an anti‐oxidative role in MDS and the tumor suppressor effect of GSTM5 may be mediated by reducing glutathione levels. GSTM5 hypermethylation and low levels of GSTM5 expression may be prognostic markers for MDS.

Inflammatory profile of lower risk myelodysplastic syndromes.

The precise link between inflammation and pathogenesis of myelodysplastic syndrome (MDS) is yet to be fully established. We developed a novel method to measure ASC/NLRP3 protein specks which are specific for the NLRP3 inflammasome only. We combined this with cytokine profiling to characterise various inflammatory markers in a large cohort of patients with lower risk MDS in comparison to healthy controls and patients with defined autoinflammatory disorders (AIDs). The ASC/NLRP3 specks were significantly elevated in MDS patients compared to healthy controls (p < 0.001) and these levels were comparable to those found in patients with AIDs. The distribution of protein specks positive only for ASC was different to ASC/NLRP3 ones suggesting that other ASC-containing inflammasome complexes might be important in the pathogenesis of MDS. Patients with MDS-SLD had the lowest levels of interleukin (IL)-1β, tumour necrosis factor (TNF), IL-23, IL-33, interferon (IFN) γ and IFN-α2, compared to other diagnostic categories. We also found that inflammatory cytokine TNF was positively associated with MDS progression to a more aggressive form of disease and IL-6 and IL-1β with time to first red blood cell transfusion. Our study shows that there is value in analysing inflammatory biomarkers in MDS, but their diagnostic and prognostic utility is yet to be fully validated.

Germline MYOF1::WNK4 and VPS25::MYOF1 Chimeras Generated by the Constitutional Translocation t(17;19)(q21;p13) in Two Siblings With Myelodysplastic Syndrome.

Constitutional chromosomal aberrations are rare in hematologic malignancies and their pathogenetic role is mostly poorly understood. We present a comprehensive molecular characterization of a novel constitutional chromosomal translocation found in two siblings - sisters - diagnosed with myelodysplastic syndrome (MDS). Bone marrow and blood cells from the two patients were examined using G-banding, RNA sequencing, PCR, and Sanger sequencing. We identified a balanced t(17;19)(q21;p13) translocation in both siblings' bone marrow, blood cells, and phytohemagglutinin-stimulated lymphocytes. The translocation generated a MYO1F::WNK4 chimera on the der(19)t(17;19), encoding a chimeric serine/threonine kinase, and a VPS25::MYO1F on the der(17), potentially resulting in an aberrant VPS25 protein. The t(17;19)(q21;p13) translocation found in the two sisters probably predisposed them to myelodysplasia. How the MYO1F::WNK4 and/or VPS25::MYO1F chimeras, perhaps especially MYO1F::WNK4 that encodes a chimeric serine/threonine kinase, played a role in MDS pathogenesis, remains incompletely understood.

Potential Diagnostic Value of Abnormal Pyroptosis Genes Expression in Myelodysplastic Syndromes (MDS): A Primary Observational Cohort Study.

Background: Myelodysplastic syndromes (MDS) are determined by ineffective hematopoiesis and bone marrow cytological dysplasia with somatic gene mutations and chromosomal abnormalities. Accumulating evidence has revealed the pivotal role of NLRP3 inflammasome activation and pyroptotic cell death in the pathogenesis of MDS. Although MDS can be diagnosed with a variety of morphologic and cytogenetic tests, most of these tests have limitations or problems in practice. Materials and Methods: In the present study, we evaluated the expression of genes that form the inflammasome (NLRP3, ASC, and CASP1) in bone marrow specimens of MDS patients and compared the results with those of other leukemias to evaluate their diagnostic value for MDS. Primary samples of this observational cohort study were collected from aspiration samples of patients with myelodysplastic syndromes (27 cases) and patients with non-myelodysplastic syndrome hematological cancers (45 cases). After RNA extraction and c.DNA synthesis, candidate transcripts and housekeeping transcripts were measured by real-time PCR method (SYBER Green assay). Using Kruskal-Wallis the relative gene expressions were compared and differences with p value less than 0.05 were considered as significant. Discrimination capability, cut-off, and area under curve (AUC) of all markers were analyzed with recessive operation curve (ROC) analysis. Results: We found that Caspase-1 and ASC genes expressed at more levels in MDS specimens compared to non-MDS hematological malignancies. A relative average expression of 10.22 with a p-value of 0.001 and 1.86 with p=0.019 was detected for Caspase-1 and ASC, respectively. ROC curve analysis shows an AUC of 0.739 with p=0.0001 for Caspase-1 and an AUC of 0.665 with p=0.0139 for ASC to MDS discrimination. Conclusion: Our results show that Caspase-1 and ASC gene expression levels can be used as potential biomarkers for MDS diagnosis. Prospective studies with large sample numbers are suggested.

Caspase 8 deletion causes infection/inflammation-induced bone marrow failure and MDS-like disease in mice

Myelodysplastic syndromes (MDS) are a heterogeneous group of pre-leukemic hematopoietic disorders characterized by cytopenia in peripheral blood due to ineffective hematopoiesis and normo- or hypercellularity and morphologic dysplasia in bone marrow (BM). An inflammatory BM microenvironment and programmed cell death of hematopoietic stem/progenitor cells (HSPCs) are thought to be the major causes of ineffective hematopoiesis in MDS. Pyroptosis, apoptosis and necroptosis (collectively, PANoptosis) are observed in BM tissues of MDS patients, suggesting an important role of PANoptosis in MDS pathogenesis. Caspase 8 (Casp8) is a master regulator of PANoptosis, which is downregulated in HSPCs from most MDS patients and abnormally spliced in HSPCs from MDS patients with SRSF2 mutation. To study the role of PANoptosis in hematopoiesis, we generated inducible Casp8 knockout mice (Casp8−/−). Mx1-Cre-Casp8−/− mice died of BM failure within 10 days of polyI:C injections due to depletion of HSPCs. Rosa-ERT2Cre-Casp8−/− mice are healthy without significant changes in BM hematopoiesis within the first 1.5 months after Casp8 deletion. Such mice developed BM failure upon infection or low dose polyI:C/LPS injections due to the hypersensitivity of Casp8−/− HSPCs to infection or inflammation-induced necroptosis which can be prevented by Ripk3 deletion. However, impaired self-renewal capacity of Casp8−/− HSPCs cannot be rescued by Ripk3 deletion due to activation of Ripk1-Tbk1 signaling. Most importantly, mice transplanted with Casp8−/− BM cells developed MDS-like disease within 4 months of transplantation as demonstrated by anemia, thrombocytopenia and myelodysplasia. Our study suggests an essential role for a balance in Casp8, Ripk3-Mlkl and Ripk1-Tbk1 activities in the regulation of survival and self-renewal of HSPCs, the disruption of which induces inflammation and BM failure, resulting in MDS-like disease.

Construction and experimental validation of a novel ferroptosis-related gene signature for myelodysplastic syndromes.

Myelodysplastic syndromes (MDS) are clonal hematopoietic disorders characterized by morphological abnormalities and peripheral blood cytopenias, carrying a risk of progression to acute myeloid leukemia. Although ferroptosis is a promising target for MDS treatment, the specific roles of ferroptosis-related genes (FRGs) in MDS diagnosis have not been elucidated. MDS-related microarray data were obtained from the Gene Expression Omnibus database. A comprehensive analysis of FRG expression levels in patients with MDS and controls was conducted, followed by the use of multiple machine learning methods to establish prediction models. The predictive ability of the optimal model was evaluated using nomogram analysis and an external data set. Functional analysis was applied to explore the underlying mechanisms. The mRNA levels of the model genes were verified in MDS clinical samples by quantitative real-time polymerase chain reaction (qRT-PCR). The extreme gradient boosting model demonstrated the best performance, leading to the identification of a panel of six signature genes: SREBF1, PTPN6, PARP9, MAP3K11, MDM4, and EZH2. Receiver operating characteristic curves indicated that the model exhibited high accuracy in predicting MDS diagnosis, with area under the curve values of 0.989 and 0.962 for the training and validation cohorts, respectively. Functional analysis revealed significant associations between these genes and the infiltrating immune cells. The expression levels of these genes were successfully verified in MDS clinical samples. Our study is the first to identify a novel model using FRGs to predict the risk of developing MDS. FRGs may be implicated in MDS pathogenesis through immune-related pathways. These findings highlight the intricate correlation between ferroptosis and MDS, offering insights that may aid in identifying potential therapeutic targets for this debilitating disorder.

Impaired binding affinity of YTHDC1 with METTL3/METTL14 results in R-loop accumulation in myelodysplastic neoplasms with DDX41 mutation

DEAD box helicase 41 (DDX41) mutations are the most prevalent predisposition to familial myelodysplastic syndrome (MDS). However, the precise roles of these variants in the pathogenesis of MDS have yet to be elucidated. Here, we discovered a novel mechanism by which DDX41 contributes to R-loop-induced DNA damage responses (DDR) in cooperation with the m6A-METTL complex (MAC) and YTHDC1 using DDX41 knockout (KO) and DDX41 knock-in (KI, R525H, Y259C) cell lines as well as primary samples from MDS patients. Compared to wild type (WT), DDX41 KO and KI led to increased levels of m6A RNA methylated R-loop. Interestingly, we found that DDX41 regulates m6A/R-loop levels by interacting with MAC components. Further, DDX41 promoted the recruitment of YTHDC1 to R-loops by promoting the binding between METTL3 and YTHDC1, which was dysregulated in DDX41-deficient cells, contributing to genomic instability. Collectively, we demonstrated that DDX41 plays a key role in the physiological control of R-loops in cooperation with MAC and YTHDC1. These findings provide novel insights into how defects in DDX41 influence MDS pathogenesis and suggest potential therapeutic targets for the treatment of MDS.

The role of genetic factors in pediatric myelodysplastic syndromes with different outcomes

BackgroundPediatric myelodysplastic syndromes (MDS) are rare disorders with an unrevealed pathogenesis. Our aim is to explore the role of genetic factors in the pathogenesis of MDS in children with different outcomes and to discover the correlation between genetic features and clinical outcomes as well as disease characteristics.MethodsWe conducted an analysis of archived genetic data from 26 patients diagnosed with pediatric MDS at our institution between 2015 and 2021, examining the association between different genetic characteristics and clinical manifestations as well as prognosis. Additionally, We presented three cases with distinct genetic background and outcomes as examples to elaborate the role of genetic factors in pediatric MDS with different prognoses.ResultsGenetic variations were detected in 13 out of the 26 patients, including 8 patients with co-occurrence of somatic and germline mutations (CSGMs) and 5 patients with somatic mutations alone. Our analysis revealed that advanced MDS (4/8, 50% vs. 1/5, 20% and 4/11, 36.4%), PD (3/8, 37.5% vs. 1/5, 20% and 1/11 9.1%), and TD (6/8, 75% vs. 2/5, 40% and 2/11, 18.2%) were more common in patients with CSGMs than those with somatic mutations alone or without any mutations. We also found out in our study that 8 patients with CSGMs had evidently different clinical outcomes, and we presented 3 of them as examples for elaboration. Case 1 with germline and somatic mutations of unknown significance had a relatively slow disease course and a good prognosis. Case 2 with compound heterozygous germline SBDS variants and somatic mutations like del20q had a stable disease course and a reversed outcome. Case 3 with a germline GATA2 variant and somatic mutations including − 7 had a rapidly progressive disease course and a worst prognosis.ConclusionOur findings indicate that genetic background of pediatric MDS is closely linked with disease characteristics as well as outcomes and that CSGMs may lead to disease progression. It should be emphasized that the interaction between certain germline variants and somatic mutations, such as SBDS and del20q, may result in hematopoietic stem cell adaptation (improved hematopoiesis) and reversed clinical outcomes, which can facilitate the development of targeted therapy.

Infection stress and a driver mutation interact to promote transformation to hematological malignancies

Myelodysplastic syndrome (MDS) is a refractory cancer that arises from hematopoietic stem cells and predominantly affects elderly adults. In addition to driver gene mutations, which are also found in clonal hematopoiesis in healthy elderly people, systemic inflammation caused by infection or collagen disease has long been known as an extracellular factor in the pathogenesis of MDS. Wild-type HSCs have an "innate immune memory" that functions in response to infection and inflammatory stress, and my colleagues and I used an infection stress model to demonstrate that the innate immune response by the TLR-TRIF-PLK-ELF1 pathway is similarly critical in impairment of hematopoiesis and dysregulation of chromatin in MDS stem cells. This revealed that not only are MDS stem cells expanded by the TRAF6-NF-kB pathway, the innate immune response is also involved in generating MDS stem cells. In this review, I will present research findings related to "innate immune memory," one of the pathogenic mechanisms of blood cancer, and discuss future directions for basic pathological research and potential therapeutic development.

Pathogenesis of myelodysplastic syndromes by excessive mitochondrial fragmentation

Myelodysplastic syndromes (MDS) are a group of heterogenous hematopoietic stem cell (HSC) malignancies characterized by ineffective hematopoiesis in which clonal progenitor expansion occurs alongside impaired myelopoiesis. Inflammatory signaling activation due to dysregulated innate immunity is also a hallmark of MDS pathogenesis. We recently established a useful preclinical tool that recapitulates bona fide MDS phenotypes and gene expression profiles based on previously unreported co-mutations discovered during our clinical surveillance of mutations in patients with MDS. Notably, we focused unbiased transcriptome analysis on determining the distinct underlying mediators of MDS etiology, and identified excessive mitochondrial fission-mediated fragmentation in mutant HSCs and progenitors (HSC/Ps). We confirmed excessive mitochondrial fragmentation in HSC/Ps obtained from patients with MDS regardless of the mutational profile. Importantly, in vivo pharmacological inhibition of mitochondrial fission significantly attenuated inflammatory signaling activation, dysplasia formation and ineffective hematopoiesis phenotype, and prolonged survival of MDS mice, suggesting that excessive mitochondrial fragmentation could be a fundamental trigger of MDS pathogenesis. These findings provide new insights into the mechanistic basis of ineffective hematopoiesis, and a clue for targeting bone marrow failure caused by ineffective hematopoiesis in MDS.

MicroRNA dysregulation in myelodysplastic syndromes: implications for diagnosis, prognosis, and therapeutic response.

Myelodysplastic syndromes (MDS) are a group of malignant clonal hematological disorders with heterogeneous clinical course and risk of transformation to acute myeloid leukemia. Genetic and epigenetic dysregulation, including alterations in microRNA (miRNA) expression, plays a pivotal role in MDS pathogenesis influencing disease development and progression. MiRNAs, known for their regulatory roles in gene expression, have emerged as promising biomarkers in various malignant diseases. This review aims to explore the diagnostic and prognostic roles of miRNAs in MDS. We discuss research efforts aimed at understanding the clinical utility of miRNAs in MDS management. MiRNA dysregulation is linked to specific chromosomal abnormalities in MDS, providing insights into the molecular landscape of the disease. Circulating miRNAs in plasma offer a less invasive avenue for diagnostic and prognostic assessment, with distinct miRNA profiles identified in MDS patients. Additionally, we discuss investigations concerning the role of miRNAs as markers for treatment response to hypomethylating and immunomodulating agents, which could lead to improved treatment decision-making and monitoring. Despite significant progress, further research in larger patient cohorts is needed to fully elucidate the role of miRNAs in MDS pathogenesis and refine personalized approaches to patient care.

Caspase 8 Deletion Causes Infection/Inflammation-Induced MDS-like Bone Marrow Failure in Mice

Myelodysplastic syndromes (MDS) are a heterogeneous group of pre-leukemic hematopoietic disorders characterized by persistent cytopenia in peripheral blood (PB) and normo- or hypercellular and morphologic dysplasia in bone marrow (BM) due to ineffective hematopoiesis, as well as resulting in an elevated risk for leukemic transformation. Bacterial or viral infections increase the severity of MDS patients' symptoms. An inflammatory BM micro-environment and programmed cell death of hematopoietic stem/progenitor cells (HSPCs) have been thought to be the major causes leading to ineffective hematopoiesis. Three types of programed cell death, apoptosis, necroptosis and pyroptosis, were observed in BM tissues of MDS patients, suggesting PANoptosis might play a critical role in the pathogenesis of MDS. Caspase 8 (Casp8) is a master regulator of PANoptosis. Casp8 is downregulated in HSPCs from patients with MDS, and is associated with increased Ripk1 protein, which is another master regulator of PANoptosis. To study the role of PANoptosis in normal hematopoiesis and the pathogenesis of MDS, we generated Mx1-Cre and Rosa-ERT 2Cre-mediated inducible C asp8 knockout mice ( Casp8 -/-). Mx1-CreCasp8 -/- mice died of BM failure within 10 days of three polyI:C injections (administered every other day) due to the massive depletion of HSPCs. This could be completely rescued by Ripk3 deletion, suggesting that HSPCs were eliminated by necroptosis. Rosa-ERT 2Cre- Casp8 -/- mice are completely normal without any significant changes in BM hematopoiesis after induction by five doses of tamoxifen (TAM) when maintained in specific pathogen-free facilities. However, such mice developed a spontaneous BM failure phenotype when maintained in quarantine facilities. This BM failure can be attenuated by antibiotic treatment, suggesting that the phenotype is infection-induced. In addition, low dose polyI:C injections or treatment with LPS also induces BM failure in Rosa-ERT 2Cre - Casp8 -/- mice living in germ-free conditions. Detailed analysis suggested that Casp8 -/- HSPCs are hypersensitive to polyI:C, LPS, TNFα and IFNα/γ-induced cell death. Most importantly, all these phenotypic and functional abnormalities observed in Rosa-ERT 2Cre- Casp8 -/- mice can be completely prevented by Ripk3 deletion. In addition, serial transplantationstudy demonstrated that Casp8 -/- HSCs have impaired self-renewal capacity. Interestingly, the self-renewal of Casp8 -/-Ripk3 -/- HSCs is significantly enhanced compared to Wild-type HSCs. Our study suggests an essential role for a balance in Casp8 and Ripk3 activities in the regulation of normal hematopoiesis and the self-renewal of HSCs, the disruption of which might induce inflammation and BM failure, resulting in MDS-like disease.

Changes in Immune-Related Indicators in Patients with Hematopoietic Abnormalities and Their Impact on Clinical Symptoms

Background: The pathogenesis of myelodysplastic syndrome (MDS) is mainly driven by specific genetic lesions involving stem cell compartments. But recent studies have found that MDS also appears to be related to immune mechanisms. There is still no consensus on which immune pathway is involved. As a result, we investigated the potential implications of various immune cell subpopulations on hematopoietic abnormalities disease occurrence and development. Methods: 69 MDS patients in our hospital and 31 normal controls are involved. Clinical data were collected and immune-related indicators were detected through blood routine testing, flow cytometry, ELISA, and other testing methods. Then we analyzed the differences between immune groups in patients and normal individuals, as well as the correlation between the immune group and clinical symptoms. Results: In lymphocytes, the activated T cell population was significantly increased in patients with MDS (p&amp;lt;0.01), with CD4 + T cell being the most significantly elevated (p&amp;lt;0.01). In atypical T cell subtypes, NK-T was the most significantly reduced (p&amp;lt;0.01). Among immune cell receptors, the NK-P46 was significantly increased (p&amp;lt;0.01). And there was a significant decrease in immune cell activity experiments (p&amp;lt;0.01). In the correlation study, we found a negative correlation between neutrophils and NK-NKG2D cells (r=-0.52, p&amp;lt;0.01), and a positive correlation between bone marrow progenitor cells and Th17 (r=0.47, p&amp;lt;0.05). (figure 1) Conclusion: It has been confirmed that the immune mechanism has indeed had an impact on MDS. We found a significant increase in the T cell population but a decrease in immune cell function in patients with MDS. Indicating a new direction for studying immune mechanisms in MDS patients.

Impact of Genomic Landscape and Mutational Burden on Primary Endpoint Responses in the COMMANDS Study

Background: Myelodysplastic syndromes (MDS)-related anemia leads to significant morbidity, due to impaired oxygen transport and red blood cell transfusion (RBCT)-related iron overload. Erythropoiesis-stimulating agents (ESAs) are used to treat anemia and decrease transfusion burden and are effective in ~ 35% of patients (pts) with lower-risk (LR)-MDS. Luspatercept is approved for pts with LR-MDS refractory/intolerant to ESAs who need regular RBCTs. Primary resistance to ESAs is frequent, and ~ 70% of responders relapse in &amp;lt; 2 years. Baseline (BL) erythropoietin level ≤ 200 U/L and ≤ 2 somatic mutations are prognostic factors for better ESA response. An association of driver gene mutations with deteriorating clinical outcomes is well established in LR-MDS (Papaemmanuil E, et al. Blood 2013;122:3616-3627; Bersanelli M, et al. J Clin Oncol 2021;39:1223-1233; Nazha A, et al. J Clin Oncol 2021;39:3737-3746). The Molecular International Prognostic Scoring System (IPSS-M; Bernard E, et al. NEJM Evidence 2022;1(7):EVIDoa2200008) was developed to improve upon the shortcomings of the Revised IPSS (IPSS-R) and restratified ~ 46% of pts by adding genomic profiling to existing hematologic and cytogenetic parameters. Pts with LR-MDS typically harbor a median of 2-3 driver mutations in genes involved in MDS pathogenesis. Methods: Individual pt bone marrow samples were prepared for sequencing using the Illumina ® DNA prep with enrichment and the xGen™ hybridization capture of DNA libraries. Exon coverage was ≥ 400X for 3% sensitivity. Sequencing libraries were run on the NovaSeq6000 (Illumina ®) system and statistical analyses were conducted using R. A targeted panel of 82 genes was used. Results: At BL, 322/363 pts enrolled in the COMMANDS trial had somatic mutations in ≥ 1 gene; 11 pts did not have mutation data. Most mutations had a variant allele frequency of 3%-50%. In the intent-to-treat (ITT) population, the luspatercept arm did not show any significant differences in BL mutational burden (MB, defined as the number of gene mutations from the myeloid gene panel) between responders (R) and non-responders (NR). Interestingly, R in the ESA arm trended ( P = 0.065) towards lower MB compared with NR. Subgroup analysis revealed that ring sideroblast (RS)− pts in the ESA arm had lower MB at BL (median 1 gene mutation) compared with RS+ pts (2 gene mutations; P = 0.0004). However, no significant difference was observed in the luspatercept arm. In the ITT population (and the RS+ subgroup), compared with ESAs, luspatercept showed robust responses (Figure A) in pts with 1 (63% vs 40%; Fisher's P = 0.040), 2 (70% vs 27%; Fisher's P &amp;lt; 0.001), and 3 (72% vs 40%; Fisher's P = 0.018) gene mutations. However, in the RS− subgroup, luspatercept and ESAs had similar response rates independent of MB. Interestingly, more RS− pts in the luspatercept arm had ≥ 4 gene mutations (12/47 pts [26%]) versus the ESA arm (only 3 pts [6.4%]). Furthermore, these ≥ 4 mutations were in genes associated with shorter leukemia-free survival, overall survival, and progression-free survival. Of the RS− pts in the luspatercept arm, 9/12 were NR, compared to 2/3 in the ESA arm. Luspatercept showed superior clinical benefit in pts with difficult-to-treat mutations (such as ASXL1, TET2 DNMT3A ZRSR2) and favorability in pts with mutations in SRSF2 EZH2, TP53, DTA.SF3B1.n and IDH2. Primary endpoint analysis by IPSS-M (Figure B) also showed superior clinical benefit of luspatercept across risk groups compared with ESAs: Low (75% vs 38%); Moderate low (61% vs 38%); Moderate high (44% vs 21%); and High (36% vs 24%). Conclusion: In pts in the COMMANDS trial,BL MB impacted response to ESAs but not to luspatercept. In both ITT and RS+ pts, luspatercept showed either superior or comparable clinical benefit in pts with LR-MDS with various BL MB. Interestingly, both luspatercept and ESAs had similar clinical benefit across various MB in the RS− subgroup. However, lower MB favored higher responses to ESAs in the RS− subgroup, and higher MB in genes associated with poor prognosis significantly impacted response rates in the luspatercept arm. Despite the presence of these imbalances in BL MB, RS− pts had similar response rates to luspatercept as to ESAs. Pts with LR-MDS with difficult-to-treat mutations also showed superior or favorable clinical benefit with luspatercept. Finally, luspatercept showed superior clinical benefit to ESAs in pts with LR-MDS across all IPSS-M risk groups.