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This study focused on the impact of the treatment with the hypomethylating agent 5-azacitidine on the redox status and inflammation in 24 MDS patients. Clinical and genetic features of MDS patients were recorded, and peripheral blood samples were used to determine the activity of the endogenous antioxidant defense system (superoxide dismutase, SOD; catalase, CAT; glutathion peroxidase, GPx; and reductase, GRd, activities), markers of oxidative damage (lipid peroxidation, LPO, and advanced oxidation protein products, AOPP). Moreover, pro-inflammatory cytokines and plasma nitrite plus nitrate levels as markers of inflammation, as well as CoQ10 plasma levels, were also measured. Globally, MDS patients showed less redox status in terms of a reduction in the GSSG/GSH ratio and in the LPO levels, as well as increased CAT activity compared with healthy subjects, with no changes in SOD, GPx, and GRd activities, or AOPP levels. When analyzing the evolution from early to advanced stages of the disease, we found that the GPx activity, GSSG/GSH ratio, LPO, and AOPP increased, with a reduction in CAT. GPx changes were related to the presence of risk factors such as high-risk IPSS-R or mutational score. Moreover, there was an increase in IL-2, IL-6, IL-8, and TNF-α plasma levels, with a further increase of IL-2 and IL-10 from early to advanced stages of the disease. However, we did not observe any association between inflammation and oxidative stress. Finally, 5-azacitidine treatment generated oxidative stress in MDS patients, without affecting inflammation levels, suggesting that oxidative status and inflammation are two independent processes.

Aim: The objective of this article was to compare the efficiency of azacitidine (AZA) and decitabine (DAC) in patients with myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) who are not suitable for high-dose chemotherapy., Materials and Methods: MDS and AML patients who were treated with hypomethylating agents (HMAs) between January 2005 and 2020 were evaluated retrospectively., Results: No statistically significant difference was found between the patients who received AZA or DAC in AML patients. In MDS group, the rate of patients who achieved remission was statistically significantly higher in patients who received DAC (p = 0.032)., Conclusion: The advantage in terms of response for MDS and no survival difference between AZA and DAC for AML and MDS patients will be an important contribution to the literature., Competing Interests: Financial & competing interests disclosure The authors have no relevant affiliations or financial involvement with any organization or entity with a financial interest in or financial conflict with the subject matter or materials discussed in the manuscript. This includes employment, consultancies, honoraria, stock ownership or options, expert testimony, grants or patents received or pending, or royalties. No writing assistance was utilized in the production of this manuscript., (© 2021 Istemi Serin.)

The natural history of patients with myelodysplastic syndrome (MDS) is dependent upon the presence and magnitude of diverse genetic and molecular aberrations. The International Prognostic Scoring System (IPSS) and revised IPSS (IPSS-R) are the most widely used classification and prognostic systems; however, somatic mutations are not currently incorporated into these systems, despite evidence of their independent impact on prognosis. Our manuscript reviews prognostic information for TP53, EZH2, DNMT3A, ASXL1, RUNX1, SRSF2, CBL, IDH 1/2, TET2, BCOR, ETV6, GATA2, U2AF1, ZRSR2, RAS, STAG2, and SF3B1. Mutations in TP53, EZH2, ASXL1, DNMT3A, RUNX1, SRSF2, and CBL have extensive evidence for their negative impact on survival, whereas SF3B1 is the lone mutation carrying a favorable prognosis. We use the existing literature to propose the incorporation of somatic mutations into the IPSS-R. More data are needed to define the broad spectrum of other genetic lesions, as well as the impact of variant allele frequencies, class of mutation, and impact of multiple interactive genomic lesions. We postulate that the incorporation of these data into MDS prognostication systems will not only enhance our therapeutic decision making but lead to targeted treatment in an attempt to improve outcomes in this formidable disease., Competing Interests: The authors declare no conflict of interest., (© 2021 The Authors. eJHaem published by British Society for Haematology and John Wiley & Sons Ltd.)

Background: Myelodysplastic syndrome (MDS) is a group of hematological malignancies that may progress to acute myeloid leukemia (AML). Bioinformatics-based analysis of high-frequency mutation genes in MDS-related patients is still relatively rare, so we conducted our research to explore whether high-frequency mutation genes in MDS-related patients can play a reference role in clinical guidance and prognosis., Methods: Next generation sequencing (NGS) technology was used to detect 32 mutations in 64 MDS-related patients. We classified the patients' genes and analyzed them by Gene Ontology (GO) analysis, Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis, protein-protein interaction (PPI) analysis, and then calculated the gene survival curve of high-frequency mutations., Results: We discovered 32 mutant genes such as ASXL1 , DNMT3A , KRAS , NRAS , TP53 , SF3B1 , and SRSF2 . The overall survival (OS) of these genes decreased significantly after DNMT3A , ASXL1 , RUNX1 , and U2AF1 occurred mutation. These genes play a significant role in biological processes, not only in MDS but also in the occurrence and development of other diseases. Through retrospective analysis, genes associated with MDS-related diseases were identified, and their effects on the disease were predicted., Conclusions: Thirty-two mutant genes were determined in MDS and when mutations occur in DNMT3A , ASXL1 , RUNX1 , and U2AF1 , their survival time decreases significantly. This results providing a theoretical basis for clinical and scientific research and broadening the scope of research on MDS., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at https://dx.doi.org/10.21037/atm-21-4094). The authors have no conflicts of interest to declare., (2021 Annals of Translational Medicine. All rights reserved.)

Simple Summary: Prognosis for acute myeloid leukemia (AML) patients is poor, particularly in TP53 mutated AML, secondary, relapsed, and refractory AML, and in patients unfit for intensive treatment, thus highlighting an unmet need for novel therapeutic approaches. Targeting the stem cell oncoprotein BMI1 in leukemic cells may represent a promising novel treatment option for poor risk AML patients, especially in combination with other targeted therapies. Here we tested the BMI1 inhibitor PTC596 in combination with a variety of targeted therapies in AML cell lines and patient samples in vitro. In addition, we defined the biomarkers of response to the combination treatments in the leukemic cells. The combination treatment with the BMI1 inhibitor PTC596 and the MCL1 inhibitor S63845 may be an effective treatment in CD34+ adverse risk AML with elevated MN1 gene expression and MCL1 protein levels, while combination treatment with BMI1 inhibitor PTC596 and the MEK inhibitor trametinib may be more effective in CD34+ adverse risk AML with elevated BMI1 gene expression and MEK protein levels. The determination of gene and protein expression levels in leukemic cells as biomarkers of response to targeted combination therapies may be helpful to optimize treatment efficacy. Purpose: Prognosis for acute myeloid leukemia (AML) patients is poor, particularly in TP53 mutated AML, secondary, relapsed, and refractory AML, and in patients unfit for intensive treatment, thus highlighting an unmet need for novel therapeutic approaches. The combined use of compounds targeting the stem cell oncoprotein BMI1 and activating the tumor suppressor protein p53 may represent a promising novel treatment option for poor risk AML patients. Experimental Design: The BMI1 inhibitor PTC596, MCL1 inhibitor S63845, and MEK inhibitor trametinib, as well as the p53 activator APR-246 were assessed as single agents and in combination for their ability to induce apoptosis and cell death in leukemic cells. AML cells represented all major morphologic and molecular subtypes including FLT3-ITD and FLT3 wild type, NPM1 mutant and wild type, as well as TP53 mutant and wild type AML cell lines and a variety of patient derived AML cells. Results: AML cell lines were variably susceptible to PTC596 and to combination treatments with PTC596 and MCL1 inhibitor S63845, MEK inhibitor trametinib, or TP53 activator APR-246, independent of TP53 mutational status. Susceptibility of patient samples for PTC596 in combination with S63845 or trametinib was significant for the majority of adverse risk primary and secondary AML with minimal efficacy in favorable risk AML, and correlated significantly with CD34 positivity of the samples. BMI1 and MN1 gene expression, and MCL1 and MEK1 protein levels were identified as biomarkers for response to PTC596 combination treatments. Conclusions: The combination of PTC596 and S63845 may be an effective treatment in CD34+ adverse risk AML with elevated MN1 gene expression and MCL1 protein levels, while PTC596 and trametinib may be more effective in CD34+ adverse risk AML with elevated BMI1 gene expression and MEK protein levels. [ABSTRACT FROM AUTHOR]

Tet methylcytosine dioxygenase 2 (TET2) is one of the most frequently mutated genes in myelodysplastic syndrome (MDS). TET2 is known to involve a demethylation process, and the loss of TET2 is thought to cause DNA hypermethylation. Loss of TET2 function is known to be caused by genetic mutations and miRNA, such as miR-22. We analyzed 41 MDS patients receiving hypomethylating therapy (HMT) to assess whether TET2 mutation status and miR-22 expression status were associated with their clinical characteristics and treatment outcomes. Responsiveness to HMT was not affected by both TET2 mutation (odds ratio (OR) 0.900, p = 0.909) and high miR-22 expression (OR 1.548, p = 0.631). There was a tendency for TET2 mutation to be associated with lower-risk disease based on IPSS (Gamma = -0.674, p = 0.073), lower leukemic transformation (OR 0.170, p = 0.040) and longer survival (Hazard ratio 0.354, p = 0.059). Although high miR-22 expression also showed a similar tendency, this tendency was weaker than that of TET2 mutation. In summary, the loss of TET2 function, including both TET2 mutation and high miR-22 expression, was not a good biomarker for predicting the response to HMT but may be associated with lower-risk disease based on IPSS, lower leukemic transformation and longer survival.

Iron overload is related to leukemia transformation in myelodysplastic syndrome (MDS) patients. Siderophores help to transport iron. Type 2-hydroxybutyrate dehydrogenase (BDH2) is a rate-limiting factor in the biogenesis of siderophores. Using qRT-PCR, we analyze BDH2mRNA expression in the bone marrow (BM) of 187 MDS patients, 119 de novo acute myeloid leukemia (AML) patients, and 43 lymphoma patients with normal BM. Elevated BDH2mRNA expression in BM is observed in MDS patients (n = 187 vs. 43, normal BM; P = 0.009), and this is related to ferritin levels. Patients with higher BDH2 expression show a greater risk of leukemia progression (15.25% vs. 3.77%, lower expression; P = 0.017) and shorter leukemia-free-survival (medium LFS, 9 years vs. 7 years; P = 0.024), as do patients with a ferritin level ≥350 ng/mL. Additionally, we investigate the mechanisms related to the prognostic ability of BDH2 by using BDH2-KD THP1. The cell cycle analysis, surface markers, and special stain studies indicate that BDH2-KD induces differentiation and decreases the growth rate of THP1 cells, which is associated with the retardation of the cell cycle. Moreover, many genes, including genes related to mitochondrial catabolism, oncogenes, tumor suppressor genes, and genes related to cell differentiation and proliferation influence BDH2-KD THP1 cells. Herein, we demonstrate that BDH2 is involved in cell cycle arrest and the inhibition of differentiation in malignant cells. Furthermore, the high BDH2 expression in MDS patients could be suggestive of a poor prognostic factor. This study provides a foundation for further research on the roles of BDH2 and iron metabolism in the pathogenesis of MDS. [ABSTRACT FROM AUTHOR]

Monitoring minimal residual disease (MRD) provides important information during treatment of hematologic malignancies. Chimerism analysis also provides key information after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Recent advances in next-generation sequencing (NGS) have enabled identification of various mutations and quantification of mutant allele burden. In this study, we developed a new analytic algorithm to monitor chimerism applicable to NGS multi-gene panel in use to identify mutations of myelodysplastic syndrome (MDS). We enrolled patients who were diagnosed with MDS and received allo-HSCT and their corresponding donors. Monitoring MRD by NGS assay was performed using 53 DNA samples by calculating mutant allele burden after treatment. For monitoring chimerism by NGS, we selected 121 single nucleotide polymorphisms (SNPs) after careful stepwise evaluation and calculated average donor allele burden. Data obtained from NGS were compared with bone marrow findings, chromosome analysis and short tandem repeat (STR)-based chimerism. SNP-based NGS chimerism analysis was accurate and even superior to conventional STR method by overcoming the various technical limitations of STR. In addition, simultaneous monitoring of mutation and chimerism using NGS could implement comprehensive pre- and post-HSCT monitoring of various clinical conditions such as complete donor chimerism, persistent mixed chimerism, early relapse, and even donor cell-derived diseases. [ABSTRACT FROM AUTHOR]

The mRNA expression level of the gene delta-like (Dlk), coding for a signal transducer related to the Delta-Notch family, was measured using real-time PCR methodology in a large series of control biopsies (n=61) and bone marrow trephines from patients with myelodysplastic syndrome (MDS) (n=93) and related myeloid disorders (AML, n=16 and chronic myeloproliferative disease (CMPD), n=38). It turned out that dlk is strongly overexpressed in a subset of MDS (16%) cases, however with higher frequency in blast rich MDS cases. Therefore, the quantitative detection of dlk mRNA can support the morphological diagnosis of MDS in selected cases. [Copyright &y& Elsevier]

Background: Myelodysplastic syndrome (MDS) is a group of disorders involving hemopoietic dysfunction leading to leukemia. Although recently progress has been made in identifying underlying genetic mutations, many questions still remain. Animal models of MDS have been produced by introduction of specific mutations. However, there is no spontaneous mouse model of MDS, and an animal model to simulate natural MDS pathogenesis is urgently needed., Methods: In characterizing the genetically diverse mouse strains of the Collaborative Cross (CC) we observed that one, designated JUN, had abnormal hematological traits. This strain was thus further analyzed for phenotypic and pathological identification, comparing the changes in each cell population in peripheral blood and in bone marrow., Results: In a specific-pathogen free environment, mice of the JUN strain are relatively thin, with healthy appearance. However, in a conventional environment, they become lethargic, develop wrinkled yellow hair, have loose and light stools, and are prone to infections. We found that the mice were cytopenic, which was due to abnormal differentiation of multipotent bone marrow progenitor cells. These are common characteristics of MDS., Conclusions: A mouse strain, JUN, was found displaying spontaneous myelodysplastic syndrome. This strain has the advantage over existing models in that it develops MDS spontaneously and is more similar to human MDS than genetically modified mouse models. JUN mice will be an important tool for pathogenesis research of MDS and for evaluation of new drugs and treatments., Competing Interests: The authors declared no conflict of interest., (© 2021 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

Background: Cytopenia is the primary phenomenon in myelodysplastic syndrome (MDS) amidst hypercellular bone marrow. The soluble CD40 ligand (sCD40L) is considered as a cytokine that can trigger synthesis of tumor necrosis factor α (TNFα) that promotes apoptosis. The objective of this study is to prove that recombinant human sCD40L (rh-sCD40L) exposure on bone marrow mononuclear cells (BMMC) MDS increases TNFα expression at mRNA level and at protein level., Methods: BMMC from MDS patients whom diagnosed and classified using the WHO 2008 criteria, were exposed to rh-sCD40L and antiCD40L. The expressions of TNFα mRNAs were quantified by qRT-PCR, level of TNFα were measured using the ELISA method., Results: Exposure of rh-sCD40L significantly increased the expression of TNFα mRNA. The similar exposure also significantly increased the level of TNFα compared to controls. TNFα mRNA expression on BMMC in MDS samples exposed to rh-sCD40L is 3.32 times compared to TNFα mRNA expression without exposure. level of TNFα in supernatant media exposed to rh-sCD40L in MDS samples was higher than that of control samples which were 44.44 and 4.85 pg/mL, P=0.018., Conclusions: The sCD40L plays a role in increasing the synthesis of TNFα in mRNA level and protein level in BMMC MDS., Competing Interests: Conflicts of Interest: All authors have completed the ICMJE uniform disclosure form (available at http://dx.doi.org/10.21037/sci-2020-025). Dr. AI reports in addition, she has a patent (Title: “Skema Mekanisme Induksi Sintesis TNFa Oleh SCD40L Pada BMMC MDS”; Entity: Universitas Indonesia) licensed to EC00201931070, 26 February 2019. The other authors have no conflicts of interest to declare., (2021 Stem Cell Investigation. All rights reserved.)

Myelodysplastic syndrome (MDS) is a malignant tumor of the hematological system characterized by long-term, progressive refractory hemocytopenia. In addition, the risk of leukemia is high, and once it develops, the course of acute leukemia is short with poor curative effect. Animal models are powerful tools for studying human diseases and are highly effective preclinical platforms. Animal models of MDS can accurately show genetic aberrations and hematopoietic clone phenotypes with similar cellular features (such as impaired differentiation and increased apoptosis), and symptoms can be used to assess existing treatments. Animal models are also helpful for understanding the pathogenesis of MDS and its relationship with acute leukemia, which helps with the identification of candidate genes related to the MDS phenotype. This review summarizes the current status of animal models used to research myelodysplastic syndrome (MDS)., (© 2021 The Authors. Animal Models and Experimental Medicine published by John Wiley & Sons Australia, Ltd on behalf of The Chinese Association for Laboratory Animal Sciences.)

Epigenetic modifications play crucial roles in regulating the self-renewal and differentiation of hematopoiesis. 4SC-202, a novel inhibitor of histone lysine-specific demethylase 1 (LSD1) and class I histone deacetylases (HDACs), is a potential therapeutic agent to treat myelodysplastic syndrome (MDS). However, it remains unclarified of the mechanism of 4SC-202. In the study, we found that 4SC-202 treatment could inhibit cell viability, induce apoptosis and cause G2/M cell cycle arrest in MDS cell line SKM-1. Heme oxygenase-1 (HO-1) was correlated with disease progression and chemotherapy resistance. Here, we reported that 4SC-202 could down-regulate the expression of HO-1, and up-regulation of HO-1 could significantly attenuate the 4SC-202-induced apoptosis in SKM-1 cells. In addition, the activation of NF-κB pathway was suppressed by 4SC-202, while up-regulation of HO-1 significantly weakened the 4SC-202-induced suppression of the NF-κB pathway, thereby attenuating the efficacy of 4SC-202. However, down-regulation of HO-1 enhanced the sensitivity of 4SC-202 against SKM-1 cells. Moreover, SKM-1 cells were transfected with HO-1 overexpression lentivirus, subsequently injected into the tail vein of NOD/SCID mice, followed by administration of 4SC-202 in mice. As a result, up-regulation HO-1 could partially attenuate 4SC-202-suppressed MDS cells growth in NOD/SCID mice. In conclusion, 4SC-202 could induce apoptosis via the NF-κB pathway, and our present finding may provide a novel therapeutic strategy for MDS., Competing Interests: None., (AJTR Copyright © 2020.)

A relationship has been reported between myelodysplastic syndrome (MDS) and autoimmune disease. Behçet's disease is a multisystem inflammatory disorder with mucocutaneous, articular, gastrointestinal, neurological, and vascular manifestations. The co-occurrence of MDS with trisomy 8 and Behçet's-like disease was recently demonstrated. We herein describe a case that shows the relationship between the acquisition of trisomy 8 and occurrence of Behçet's-like disease. Immune dysregulation and altered T-cell hemostasis play an important role in the pathogenesis of Behçet's-like disease and MDS with trisomy 8., (© 2020 The Author(s).)

Information on the use of hypomethylating agents (HMAs) as a pre-transplant cytoreductive therapy in MDS is limited. We retrospectively evaluated outcomes of 172 adult MDS patients, who underwent allogeneic hematopoietic stem cell transplantation between January 2000 and December 2016. Patients were divided into three groups: group 1 - pre-transplant blasts <5% with HMA ( n  = 42), group 2 - pre-transplant blasts ≥5% with HMA ( n  = 38), group 3 - no HMA ( n  = 92). With a median follow up of 4.08 years, 1-year survival and relapse rates for groups 1, 2, and 3 were 75%, 40.2%, and 60.71%, respectively; and 17.6%, 26.6%, and 9.8%, respectively. Multivariate analysis revealed adverse relapse (HR 3.54; p  = .03) in group 2 compared to groups 1 and 3, while no difference in overall survival was noticed. Our study shows no survival association with pre-transplant HMA; although, higher relapse rate was observed in the non-responding patients indicating possible chemotherapy resistant disease.

To determine the incidence, risk factors, and relative survival of acute myeloid leukemia (AML) secondary to myelodysplastic syndrome (MDS) in the Surveillance, Epidemiology, and End Results (SEER) database. Retrospective analysis of all patients with new MDS onset in the SEER-18 database from 2001 to 2013. We identified 36 558 patients with primary MDS. The rate of secondary AML (sAML) was 3.7% among patients 40 years or younger and 2.5% among those older than 40 (P = .039). The median transformation interval was significantly shorter for the younger group (4.04 vs 13.1 mo; P < .001). For both age groups, median overall and cancer-specific survival were significantly longer for patients who did not develop sAML. Although the younger patients survived longer than the older patients, sAML development had a more negative effect on the survival of younger patients. Female sex, age, and World Health Organization (WHO) type MDS with single lineage dysplasia (MDS-SLD) were associated with a decreased risk of sAML for older but not younger patients. Among older patients with MDS, a married status, Black race, female sex, shorter time to sAML, and WHO type MDS-SLD or MDS with ringed sideroblasts were favorable prognostic factors for survival. In the SEER database, the rate of sAML among patients with MDS is lower than that in previous reports, but these patients still have worse survival. Risk assessment should include clinical and demographic factors., (© 2019 The Authors. Hematological Oncology published by John Wiley & Sons Ltd.)

Myelodysplastic syndromes (MDS) are a heterogeneous, clonal haematopoietic disorder, with ~1/3 of patients progressing to acute myeloid leukaemia (AML). Many elderly MDS patients do not tolerate intensive therapeutic regimens, and therefore have an unmet need for better tolerated therapies. Epigenetics is important in the pathogenesis of MDS/AML with DNA methylation, and histone acetylation the most widely studied modifications. Epigenetic therapeutic agents have targeted the reversible nature of these modifications with some clinical success. The aim of this study was to characterise the molecular consequences of treatment of MDS and AML cells with the histone deacetylase inhibitor (HDACi) Romidepsin. Romidepsin as a single agent induced cell death with an increasing dose and time profile associated with increased acetylation of histone H3 lysine 9 (H3K9) and decreased HDAC activity. Gene expression profiling, qPCR, network and pathway analysis recognised that oxidation-reduction was involved in response to Romidepsin. ROS was implicated as being involved post-treatment with the involvement of TSPO and MPO. Genomic analysis uncoupled the differences in protein-DNA interactions and gene regulation. The spatial and temporal transcriptional differences associated with acetylated, mono- and tri-methylated H3K9, representative of two activation and a repression mark respectively, were identified. Bioinformatic analysis uncovered positional enrichment and transcriptional differences between these marks; a degree of overlap with increased/decreased gene expression that correlates to increased/decreased histone modification. Overall, this study has unveiled a number of underlying mechanisms of the HDACi Romidepsin that could identify potential drug combinations for use in the clinic., Competing Interests: CONFLICTS OF INTEREST The authors declare no conflicts of interest in relation to the work described in this manuscript.

We retrospectively analyzed 101 primary MDS patients with complex karyotype during January 2010 and April 2017.The median overall survival (OS) time was 13 (95% CI 9.98-16.02) months, and there was no significant difference in OS for different treatment. Chromosome 5/7 involvement was common (78.22%, 79/101) and associated with shorter OS (12 months vs. 28 months, P < 0.01) Monosomal karyotype (MK) is overlapped with CK in 79 patients, but was not statistically associated with shorter OS. While in 59 cases with genes sequenced, 57 (96.61%) patients were found to have at least one mutation of known significance, and TP53 was the most frequent (74.58%, 44/59), the median OS of patients with TP53 mutation was shorter than those without (10 vs. 27 months, P < 0.01). Multivariate analysis demonstrated that only TP53 mutation was the strongest independent prognostic factor for OS. Moreover, high variant allele frequency (VAF) of TP53 mutation (median VAF was 70.00%) was seen and associated with adverse survival (9 months vs. 13 months, p = 0.04). In conclusion, MDS patients with CK implied an unfavorable outcome regardless of any treatment, TP53 mutation occurs at a high frequency and has a higher VAF, both were associated with worse survival., (Copyright © 2018 Elsevier Inc. All rights reserved.)

The pathophysiology of impaired platelet function in acquired disorders is often poorly understood. We report two unrelated patients with hematologic malignancies associated with acquired severe bleeding diathesis, and complex platelet function abnormalities, including overproduction of the physiological inhibitor cyclic-AMP (cAMP). Patient 1, with mild macrocytic anemia and thrombocytopenia (100 x 10 9 /L), was diagnosed with chronic myelomonocytic leukemia a few months after the onset of her bleeding diathesis and our analysis of platelet function. Patient 2, with bleeding diathesis of recent onset, was studied when his myelodysplastic syndrome with excess blasts had already progressed to acute myeloid leukemia. In both patients, platelet aggregation/ATP secretion, serum thromboxane B 2 , intraplatelet content of ADP, ATP, serotonin, and fibrinogen were severely impaired. Baseline platelet cAMP levels were mildly elevated and markedly increased after stimulation by prostaglandin E 1 . In conclusion, these are the first patients with myeloid malignancies associated with acquired severe platelet dysfunction and overproduction of cAMP.

Paroxysmal nocturnal hemoglobinuria (PNH) is a rare but often debilitating disease which may lead to death in up to 35% of patients within 5 years if unrecognized and untreated. Detection of PNH and assessment of PNH clone size in RBC and WBC lineages by flow cytometric analysis has increased in importance due to the availability of novel therapies. These therapies typically block the hemolysis of red blood cells and thus significantly lower the morbidities and mortality associated with this disease. This chapter describes validated, state-of-the-art, high-sensitivity flow cytometric methodologies based on latest published testing guidelines for PNH.

The Revised International Prognostic Score and some somatic mutations in myelodysplastic syndrome (MDS) are independently associated with transformation to acute myeloid leukemia (AML). Immunity has also been implicated in the pathogenesis of MDS, although the underlying mechanism remains unclear. We performed a SNP array on chromosome 6 in CD34 + purified blasts from 19 patients diagnosed with advanced MDS and 8 patients with other myeloid malignancies to evaluate the presence of loss of heterozygosity (LOH) in HLA and its impact on disease progression. Three patients had acquired copy-neutral LOH (CN-LOH) on 6p arms, which may disrupt antigen presentation and act as a mechanism for immune system evasion. Interestingly, these patients had previously been classified at low risk of AML progression, and the poor outcome cannot be explained by the acquisition of adverse mutations. LOH HLA was not detected in the remaining 24 patients, who all had adverse risk factors. In summary, the clinical outcome of patients with advanced MDS might be influenced by HLA allelic loss, wich allows subclonal expansions to evade cytotoxic-T and NK cell attack. CN-LOH HLA may therefore be a factor favoring MDS progression to AML independently of the somatic tumor mutation load., Competing Interests: CONFLICTS OF INTEREST No potential conflicts of interest were disclosed.