Molecular pathways in myelodysplastic syndromes and acute myeloid leukemia: relationships and distinctions-a review

Functional association of NR4A3 downregulation with impaired differentiation in myeloid leukemogenesis

The coincident downregulation of NR4A1 and NR4A3 has been implicated in myeloid leukemogenesis, but it remains unknown how these two genes function in myeloid cells and how their combined downregulation promotes myeloid leukemogenesis. Since NR4A1 abrogation is thought to confer a survival and proliferation advantage to myeloid cells, we hypothesized that downregulation of NR4A3 may have a complementary effect on myeloid cell differentiation. First, we tested the association between differentiation status of leukemic cells and NR4A3 expression using two large clinical datasets from patients with different acute myeloid leukemia (AML) subtypes. The analysis revealed a close association between differentiation status and different subtypes of AML Then, we probed the effects of differentiation-inducing treatments on NR4A3 expression and NR4A3 knockdown on cell differentiation using two myeloid leukemia cell lines. Differentiation-inducing treatments caused upregulation of NR4A3, while NR4A3 knockdown prevented differentiation in both cell lines. The cell culture findings were validated using samples from chronic myeloid leukemia (CML) patients at chronic, accelerated and blastic phases, and in acute promyelocytic leukemia (APL) patients before and after all trans-retinoic acid (ATRA)-based differentiation therapy. Progressive NR4A3 downregulation was coincident with impairments in differentiation in patients during progression to blastic phase of CML, and NR4A3 expression was increased in APL patients treated with ATRA-based differentiating therapy. Together, our findings demonstrate a tight association between impaired differentiation status and NR4A3 downregulation in myeloid leukemias, providing a plausible mechanistic explanation of how myeloid leukemogenesis might occur upon concurrent downregulation of NR4A1 and NR4A3.

Circulating Small Noncoding RNAs Have Specific Expression Patterns in Plasma and Extracellular Vesicles in Myelodysplastic Syndromes and Are Predictive of Patient Outcome

Myelodysplastic syndromes (MDS) are hematopoietic stem cell disorders with large heterogeneity at the clinical and molecular levels. As diagnostic procedures shift from bone marrow biopsies towards less invasive techniques, circulating small noncoding RNAs (sncRNAs) have become of particular interest as potential novel noninvasive biomarkers of the disease. We aimed to characterize the expression profiles of circulating sncRNAs of MDS patients and to search for specific RNAs applicable as potential biomarkers. We performed small RNA-seq in paired samples of total plasma and plasma-derived extracellular vesicles (EVs) obtained from 42 patients and 17 healthy controls and analyzed the data with respect to the stage of the disease, patient survival, response to azacitidine, mutational status, and RNA editing. Significantly higher amounts of RNA material and a striking imbalance in RNA content between plasma and EVs (more than 400 significantly deregulated sncRNAs) were found in MDS patients compared to healthy controls. Moreover, the RNA content of EV cargo was more homogeneous than that of total plasma, and different RNAs were deregulated in these two types of material. Differential expression analyses identified that many hematopoiesis-related miRNAs (e.g., miR-34a, miR-125a, and miR-150) were significantly increased in MDS and that miRNAs clustered on 14q32 were specifically increased in early MDS. Only low numbers of circulating sncRNAs were significantly associated with somatic mutations in the SF3B1 or DNMT3A genes. Survival analysis defined a signature of four sncRNAs (miR-1237-3p, U33, hsa_piR_019420, and miR-548av-5p measured in EVs) as the most significantly associated with overall survival (HR = 5.866, p < 0.001). In total plasma, we identified five circulating miRNAs (miR-423-5p, miR-126-3p, miR-151a-3p, miR-125a-5p, and miR-199a-3p) whose combined expression levels could predict the response to azacitidine treatment. In conclusion, our data demonstrate that circulating sncRNAs show specific patterns in MDS and that their expression changes during disease progression, providing a rationale for the potential clinical usefulness of circulating sncRNAs in MDS prognosis. However, monitoring sncRNA levels in total plasma or in the EV fraction does not reflect one another, instead, they seem to represent distinctive snapshots of the disease and the data should be interpreted circumspectly with respect to the type of material analyzed.

The Role of FLT3-ITD Mutation on de Novo MDS in Chinese Population

BACKGROUND

FLT3 mutations have been well-studied in acute myeloid leukemia (AML), and the detection of the FLT3 gene has become a clinical routine. However, it has not been fully analyzed in other hematologic malignancies, such as myelodysplastic syndromes (MDS).

MATERIALS AND METHODS

Between 2010 and 2016, 304 adult patients with de novo MDS had the FLT3 sequence tested on their bone marrow sample. With 279 patients who had follow-up information, we also analyzed the impact of clinical and laboratory characteristics as well as FLT3 mutation status and treatment on prognosis.

RESULTS

We found that the transformation rate was 3 (42.9%) of 7 patients in the FLT3-ITD-positive group, compared with 31 (10.4%) of 297 among FLT3-ITD-negative patients (P = .033). The median progression-free survival of the FLT3-ITD mutated and wild-type groups were 43 days and 363.5 days, respectively (P < .0001). The median overall survival (OS) of the 2 groups were 218 days and 410.5 days, respectively (P < .0001). We also found that 5 factors had independent prognostic impact on OS: white blood cell counts, bone marrow blast percentage, cytogenetics, transplantation status, and FLT3-ITD mutation. Furthermore, compared with the transformation group, the non-progression group was younger (P = .034), with a lower platelet count (P = .022), a lower bone marrow blast percentage (P = .001), a lower FLT3-ITD incidence (P = .007), and a longer OS (P < .0001).

CONCLUSIONS

When observed at the MDS stage, patients harboring FLT3-ITD mutations had higher AML transformation rate, quicker disease progression, and shorter survival than wild-type patients. Nevertheless, once the disease progressed to leukemia, the impact of FLT3-ITD mutations on prognosis was slight. In addition, the prognosis of secondary AML was very poor whether there was an FLT3-ITD mutation or not.

Annotating function to differentially expressed LincRNAs in myelodysplastic syndrome using a network-based method

Motivation

Long non-coding RNAs (lncRNAs) have been implicated in the regulation of diverse biological functions. The number of newly identified lncRNAs has increased dramatically in recent years but their expression and function have not yet been described from most diseases. To elucidate lncRNA function in human disease, we have developed a novel network based method (NLCFA) integrating correlations between lncRNA, protein coding genes and noncoding miRNAs. We have also integrated target gene associations and protein-protein interactions and designed our model to provide information on the combined influence of mRNAs, lncRNAs and miRNAs on cellular signal transduction networks.

Results

We have generated lncRNA expression profiles from the CD34+ haematopoietic stem and progenitor cells (HSPCs) from patients with Myelodysplastic syndromes (MDS) and healthy donors. We report, for the first time, aberrantly expressed lncRNAs in MDS and further prioritize biologically relevant lncRNAs using the NLCFA. Taken together, our data suggests that aberrant levels of specific lncRNAs are intimately involved in network modules that control multiple cancer-associated signalling pathways and cellular processes. Importantly, our method can be applied to prioritize aberrantly expressed lncRNAs for functional validation in other diseases and biological contexts.

Availability and implementation

The method is implemented in R language and Matlab.

Contact

xizhou@wakehealth.edu.

Supplementary information

Supplementary data are available at Bioinformatics online.

DICER1 gene and miRNA dysregulation in mesenchymal stem cells of patients with myelodysplastic syndrome and acute myeloblastic leukemia

Multipotent mesenchymal stem cells (MSC) are key components of the bone marrow (BM) microenvironment. The contribution of this microenvironment to the pathophysiology of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) is not well defined. A recent study in mice demonstrated that DICER1 gene deletion in osteoprogenitor cells from the BM microenvironment suppressed osteogenic differentiation and induced MDS and AML-like haematological findings. The present study evaluated the expression profiles of microRNAs (miRNAs) and DICER1 gene in BM-derived MSC of patients with AML (n=12), MDS (n=10) and healthy controls (HC) (n=8).miRNA expression profiles were analyzed by microarray and confirmations were performed using quantitative real-time PCR (qRT-PCR). Patient MSC displayed impaired proliferative and differentiation potential compared to HC. DICER1 gene expression was lower in MSC from MDS and AML patients than HC and some differentially expressed miRNAs indicated the potential involvement of DICER1 in the pathogenesis of MDS and AML. qRT-PCR confirmation revealed down-regulated miRNAs (hsa-miR-30d-5p, hsa-miR-222-3p and hsa-miR-30a-3p in MDS; hsa-miR-1275, hsa-miR-4725-5p and hsa-miR-143-3p in AML) and over-expressed miRNAs (hsa-miR-4462 in MDS; hsa-miR-134-5p and hsa-miR-874-3p in AML) in MDS and AML. Thus, our findings validate the results of the aforementioned animal study and demonstrate downregulation of DICER1 gene and abnormal miRNA profile in MDS and AML, which may have implications for understanding MDS and AML pathogenesis and contribute to developing targeted treatment strategies.

Total coumarins of Hedyotis diffusa induces apoptosis of myelodysplastic syndrome SKM-1 cells by activation of caspases and inhibition of PI3K/Akt pathway proteins

ETHNOPHARMACOLOGICAL RELEVANCE

Hedyotis diffusa is an ethno-medicine used for anti-cancer treatment in the clinic of traditional Chinese medicine (TCM). The total coumarins of Hedyotis diffusa (TCHD) was a selected extract with observed antiproliferative activity, which has not been tested in treatment of myelodysplastic syndromes (MDS) or acute myeloid leukemia (AML).

AIM OF THE STUDY

This study aimed to evaluate the apoptosis-inducing effect of TCHD on human MDS cell line (SKM-1) and explore its action mechanism in association with caspase family and PI3K/Akt signaling pathway.

MATERIALS AND METHODS

The chemical constituents and total coumarins content of TCHD were determined by High Performance Liquid Chromatography-tandem mass spectrometry (HPLC-MS/MS) and UV-vis spectrophotometry, respectively. MTT assay, Hoechst 33258 staining, and Annexin V-FITC/PI double labeling were applied to evaluate TCHD's efficacy on SKM-1 cells. Western blot analysis was also used to clarify the action mechanism of TCHD on protein expression level.

RESULTS

Two compounds, p-coumaric acid and E-6-O-p-coumaroyl scandoside methyl ester, were identified in TCHD, and its total coumarins content reached 87.4%. By MTT assay, apoptosis-inducing effect of TCHD on SKM-1 cells was found in a dose-dependent manner after 24-48h treatment, with IC₅₀ values of 104.48μg/ml and 100.66μg/ml, respectively. Morphological and flow cytometry observation also confirmed such effect of TCHD. Western blot analysis clarified its action mechanism associating with the activation of caspases and inhibition of PI3K/Akt pathway proteins.

CONCLUSIONS

This is the first report regarding the apoptosis-inducing efficacy and mechanism of TCHD on SKM-1 cells, providing a promising candidate of TCM for MDS and AML therapy with fewer side effects.

Genomic Profile of Chronic Lymphocytic Leukemia in Korea Identified by Targeted Sequencing

Chronic lymphocytic leukemia (CLL) is extremely rare in Asian countries and there has been one report on genetic changes for 5 genes (TP53, SF3B1, NOTCH1, MYD88, and BIRC3) by Sanger sequencing in Chinese CLL. Yet studies of CLL in Asian countries using Next generation sequencing have not been reported. We aimed to characterize the genomic profiles of Korean CLL and to find out ethnic differences in somatic mutations with prognostic implications. We performed targeted sequencing for 87 gene panel using next-generation sequencing along with G-banding and fluorescent in situ hybridization (FISH) for chromosome 12, 13q14.3 deletion, 17p13 deletion, and 11q22 deletion. Overall, 36 out of 48 patients (75%) harbored at least one mutation and mean number of mutation per patient was 1.6 (range 0-6). Aberrant karyotypes were observed in 30.4% by G-banding and 66.7% by FISH. Most recurrent mutation (>10% frequency) was ATM (20.8%) followed by TP53 (14.6%), SF3B1 (10.4%), KLHL6 (8.3%), and BCOR (6.25%). Mutations of MYD88 was associated with moderate adverse prognosis by multiple comparisons (P = 0.055). Mutation frequencies of MYD88, SAMHD1, EGR2, DDX3X, ZMYM3, and MED12 showed similar incidence with Caucasians, while mutation frequencies of ATM, TP53, KLHL6, BCOR and CDKN2A tend to be higher in Koreans than in Caucasians. Especially, ATM mutation showed 1.5 fold higher incidence than Caucasians, while mutation frequencies of SF3B1, NOTCH1, CHD2 and POT1 tend to be lower in Koreans than in Caucasians. However, mutation frequencies between Caucasians and Koreans were not significantly different statistically, probably due to low number of patients. Collectively, mutational profile and adverse prognostic genes in Korean CLL were different from those of Caucasians, suggesting an ethnic difference, while profile of cytogenetic aberrations was similar to those of Caucasians.

Concurrent targeting Akt and sphingosine kinase 1 by A-674563 in acute myeloid leukemia cells

Akt signaling plays a pivotal role in acute myeloid leukemia (AML) development and progression. In the present study, we evaluated the potential anti-AML activity by a novel Akt kinase inhibitor A-674563. Our results showed that A-674563 dose-dependently inhibited survival and proliferation of U937 AML cells and six lines of human AML progenitor cells, yet sparing human peripheral blood mononuclear leukocytes (PBMCs). A-674563 activated caspase-3/9 and apoptosis in the AML cells. Reversely, the pan-caspase inhibitor z-VAD-CHO dramatically alleviated A-674563-induced AML cell apoptosis and cytotoxicity. For the molecular study, we showed that A-674563 blocked Akt activation in U937 cells and human AML progenitor cells. Further, A-674563 decreased sphingosine kinase 1 (SphK1) activity in above AML cells to deplete pro-survival sphingosine-1-phosphate (S1P) and boost pro-apoptotic ceramide production. Such an effect on SphK1 signaling by A-674563 appeared independent of Akt blockage. Significantly, K6PC-5, a novel SphK1 activator, or supplement with S1P attenuated A-674563-induced ceramide production, and subsequent U937 cell death and apoptosis. Importantly, intraperitoneal injection of A-674563 at well-tolerated doses suppressed U937 leukemic xenograft tumor growth in nude mice, whiling significantly improving the animal survival. The results of the current study demonstrate that A-674563 exerts potent anti-leukemic activity in vitro and in vivo, possibly via concurrent targeting Akt and SphK1 signalings.

Carcinogenesis: alterations in reciprocal interactions of normal functional structure of biologic systems

The evolution of biologic systems (BS) includes functional mechanisms that in some conditions may lead to the development of cancer. Using mathematical group theory and matrix analysis, previously, it was shown that normally functioning BS are steady functional structures regulated by three basis regulatory components: reciprocal links (RL), negative feedback (NFB) and positive feedback (PFB). Together, they form an integrative unit maintaining system’s autonomy and functional stability. It is proposed that phylogenetic development of different species is implemented by the splitting of “rudimentary” characters into two relatively independent functional parts that become encoded in chromosomes. The functional correlate of splitting mechanisms is RL. Inversion of phylogenetic mechanisms during ontogenetic development leads cell differentiation until cells reach mature states. Deterioration of reciprocal structure in the genome during ontogenesis gives rise of pathological conditions characterized by unsteadiness of the system. Uncontrollable cell proliferation and invasive cell growth are the leading features of the functional outcomes of malfunctioning systems. The regulatory element responsible for these changes is RL. In matrix language, pathological regulation is represented by matrices having positive values of diagonal elements (TrA > 0) and also positive values of matrix determinant (detA > 0). Regulatory structures of that kind can be obtained if the negative entry of the matrix corresponding to RL is replaced with the positive one. To describe not only normal but also pathological states of BS, a unit matrix should be added to the basis matrices representing RL, NFB and PFB. A mathematical structure corresponding to the set of these four basis functional patterns (matrices) is a split quaternion (coquaternion). The structure and specific role of basis elements comprising four-dimensional linear space of split quaternions help to understand what changes in mechanism of cell differentiation may lead to cancer development.

Increased expression of interferon signaling genes in the bone marrow microenvironment of myelodysplastic syndromes

Introduction

The bone marrow (BM) microenvironment plays an important role in the pathogenesis of myelodysplastic syndromes (MDS) through a reciprocal interaction with resident BM hematopoietic cells. We investigated the differences between BM mesenchymal stromal cells (MSCs) in MDS and normal individuals and identified genes involved in such differences.

Materials and Methods

BM-derived MSCs from 7 MDS patients (3 RCMD, 3 RAEB-1, and 1 RAEB-2) and 7 controls were cultured. Global gene expression was analyzed using a microarray.

Result

We found 314 differentially expressed genes (DEGs) in RCMD vs. control, 68 in RAEB vs. control, and 51 in RAEB vs. RCMD. All comparisons were clearly separated from one another by hierarchical clustering. The overall similarity between differential expression signatures from the RCMD vs. control comparison and the RAEB vs. control comparison was highly significant (p = 0), which indicates a common transcriptomic response in these two MDS subtypes. RCMD and RAEB simultaneously showed an up-regulation of interferon alpha/beta signaling and the ISG15 antiviral mechanism, and a significant fraction of the RAEB vs. control DEGs were also putative targets of transcription factors IRF and ICSBP. Pathways that involved RNA polymerases I and III and mitochondrial transcription were down-regulated in RAEB compared to RCMD.

Conclusion

Gene expression in the MDS BM microenvironment was different from that in normal BM and exhibited altered expression according to disease progression. The present study provides genetic evidence that inflammation and immune dysregulation responses that involve the interferon signaling pathway in the BM microenvironment are associated with MDS pathogenesis, which suggests BM MSCs as a possible therapeutic target in MDS.

Clinical implications of the quantitative detection of ID4 gene methylation in myelodysplastic syndrome

Background

Myelodysplastic syndrome (MDS) eventually transforms into acute leukemia (AL) in about 30% of patients. Hypermethylation of the inhibitor of DNA binding 4 (ID4) gene may play an important role in the initiation and development of MDS and AL. The aim of this study was to quantitatively assess ID4 gene methylation in MDS and to establish if it could be an effective method of evaluating MDS disease progression.

Methods

We examined 142 bone marrow samples from MDS patients, healthy donors and MDS-AL patients using bisulfite sequencing PCR and quantitative real-time methylation-specific PCR. The ID4 methylation rates and levels were assessed.

Results

ID4 methylation occurred in 27 patients (27/100). ID4 gene methylation was more frequent and at higher levels in patients with advanced disease stages and in high-risk subgroups according to WHO (P < 0.001, P < 0.001, respectively) and International Prognostic Scoring System (IPSS) (P = 0.002, P = 0.007, respectively) classifications. ID4 methylation levels changed during disease progression. Both methylation rates and methylation levels were significantly different between healthy donor, MDS patients and patients with MDS-AL (P < 0.001, P < 0.001, respectively). Multivariate analysis indicated that the level of ID4 methylation was an independent factor influencing overall survival. Patients with MDS showed decreased survival time with increased ID4 methylation levels (P = 0.011, hazard ratio (HR) = 2.371). Patients with ID4 methylation had shorter survival time than those without ID4 methylation (P = 0.008).

Conclusions

Our findings suggest that ID4 gene methylation might be a new biomarker for MDS monitoring and the detection of minimal residual disease.

Novel drugs for older patients with acute myeloid leukemia

Acute myeloid leukemia (AML) is the second most common form of leukemia and the most frequent cause of leukemia-related deaths in the United States. The incidence of AML increases with advancing age and the prognosis for patients with AML worsens substantially with increasing age. Many older patients are ineligible for intensive treatment and require other therapeutic approaches to optimize clinical outcome. To address this treatment gap, novel agents with varying mechanisms of action targeting different cellular processes are currently in development. Hypomethylating agents (azacitidine, decitabine, SGI-110), histone deacetylase inhibitors (vorinostat, pracinostat, panobinostat), FMS-like tyrosine kinase receptor-3 inhibitors (quizartinib, sorafenib, midostaurin, crenolanib), cytotoxic agents (clofarabine, sapacitabine, vosaroxin), cell cycle inhibitors (barasertib, volasertib, rigosertib) and monoclonal antibodies (gentuzumab ozogamicin, lintuzumab-Ac225) represent some of these promising new treatments. This review provides an overview of novel agents that have either completed or are currently in ongoing phase III trials in patients with previously untreated AML for whom intensive treatment is not an option. Other potential drugs in earlier stages of development will also be addressed in this review.

Radiation-induced bone marrow apoptosis, inflammatory bystander-type signaling and tissue cytotoxicity

PURPOSE

A study of irradiated (0.25-2 Gy) murine bone marrow has investigated the relationships between apoptotic responses of cells exposed in vivo and in vitro and between in vivo apoptosis and tissue cytotoxicity.

MATERIALS AND METHODS

The time course of reduction in bone marrow cellularity in vivo was determined by femoral cell counts and apoptosis measurements obtained using three commonly used assays. Inflammatory pro-apoptotic cytokine production at 24 h post-exposure in vivo was investigated using a bystander protocol.

RESULTS

In vivo, there is a dose- and time-dependent non-linear reduction in bone marrow cellularity up to 24 h post- irradiation not directly represented by apoptosis measurements. The majority of cells are killed within 6 h but there is on-going cell loss in vivo up to 24 h post-irradiation in the absence of elevated levels of apoptosis and associated with the induction of cytokines produced in response to the initial tumor protein 53 (p53)-dependent apoptosis.

CONCLUSION

The results demonstrate that small increases in measured apoptosis can reflect significant intramedullary cell death and with apoptotic processes being responsible for pro-inflammatory mechanisms that can contribute to additional on-going cell death. The findings demonstrate the importance of studying tissue responses when considering the mechanisms underlying the consequences of radiation exposures.

Myelodysplastic syndrome hematopoietic stem cell

Myelodysplastic syndromes (MDSs) are clonal hematopoietic stem cell (HSC) malignancies that are characterized by ineffective hematopoiesis and frequent progression to acute myeloid leukemia (AML). Thus far, few treatments can actually alter the natural history of this disease. Allogeneic stem-cell transplantation for high-risk MDS is becoming the only curative therapy probably because of the improvement of bone marrow transplant procedures. The lack of other options underscores the urgent need to develop new therapy. The prevailing model suggests that genetic and/or epigenetic alterations that occur in HSCs or HSC niche compromise HSC function, resulting in MDS; therefore, MDS HSCs are likely the ideal targets for MDS treatment. Recent encouraging advances--capturing a molecular portrait of the whole genome of MDS CD34(+) cells, including identifying altered signaling pathways and altered microRNAs--have improved our understanding of MDS pathogenesis and provided novel potential clinical targets for MDS. Here, I will briefly review the characteristics of MDS HSCs and discuss the therapeutic promise of targeting MDS HSCs.

Analyzing transformation of myelodysplastic syndrome to secondary acute myeloid leukemia using a large patient database

One-third of patients with myelodysplastic syndrome (MDS) progress to secondary acute myeloid leukemia (sAML), with its concomitant poor prognosis. Recently, multiple mutations have been identified in association with MDS-to-sAMLtransition, but it is still unclear whether all these mutations are necessary for transformation. If multiple independent mutations are required for the transformation, sAML risk should increase with time from MDS diagnosis. In contrast, if a single critical biological event determines sAML transformation; its risk should be constant in time elapsing from MDS diagnosis. To elucidate this question, we studied a database of 1079 patients with MDS. We classified patients according to the International Prognostic Scoring System (IPSS), using either the French-American-British (FAB) or the World Health Organization (WHO) criteria, and statistically analyzed the resulting transformation risk curves of each group. The risk of transformation after MDS diagnosis remained constant in time within three out of four risk groups, and in all four risk groups, when patients were classified according to FAB or to the WHO-determined criteria, respectively. Further subdivision by blast percentage or cytogenetics had no influence on this result. Our analysis suggests that a single random biological event leads to transformation to sAML, thus calling for the exclusion of time since MDS diagnosis from the clinical decision-making process.

Phase 1 dose-ranging study of ezatiostat hydrochloride in combination with lenalidomide in patients with non-deletion (5q) low to intermediate-1 risk myelodysplastic syndrome (MDS)

Background

Ezatiostat, a glutathione S-transferase P1-1 inhibitor, promotes the maturation of hematopoietic progenitors and induces apoptosis in cancer cells.

Results

Ezatiostat was administered to 19 patients with non-deletion(5q) myelodysplastic syndrome (MDS) at one of two doses (2000 mg or 2500 mg/day) in combination with 10 mg of lenalidomide on days 1–21 of a 28-day cycle. No unexpected toxicities occurred and the incidence and severity of adverse events (AEs) were consistent with that expected for each drug alone. The most common non-hematologic AEs related to ezatiostat in combination with lenalidomide were mostly grade 1 and 2 fatigue, anorexia, nausea, diarrhea, and vomiting; hematologic AEs due to lenalidomide were thrombocytopenia, neutropenia, and anemia. One of 4 evaluable patients (25%) in the 2500/10 mg dose group experienced an erythroid hematologic improvement (HI-E) response by 2006 MDS International Working Group (IWG) criteria. Four of 10 evaluable patients (40%) in the 2000 mg/10 mg dose group experienced an HI-E response. Three of 7 (43%) red blood cell (RBC) transfusion-dependent patients became RBC transfusion independent, including one patient for whom prior lenalidomide monotherapy was ineffective. Three of 5 (60%) thrombocytopenic patients had an HI-platelet (HI-P) response. Bilineage HI-E and HI-P responses occurred in 3 of 5 (60%), 1 of 3 with HI-E and HI-N (33%), and 1 of 3 with HI-N and HI-P (33%). One of 3 patients (33%) with pancytopenia experienced a complete trilineage response. All multilineage responses were observed in the 2000/10 mg doses recommended for future studies.

Conclusions

The tolerability and activity profile of ezatiostat co-administered with lenalidomide supports the further development of ezatiostat in combination with lenalidomide in MDS and also encourages studies of this combination in other hematologic malignancies where lenalidomide is active.

Trial registration

Clinicaltrials.gov: NCT01062152

The effects of increased expression of DLK1 gene on the pathogenesis of myelodysplastic syndromes

To study the potential role of Delta-like-1 (DLK1) in myelodysplastic syndromes (MDS), we carried out a series of experiments and found that DLK1 mRNA levels are dysregulated in patients with MDS or acute myelogenous leukemia (AML), and its overexpression leads to dysfunction of 32D and 3T3 cells. We conclude that DLK1 dysfunction may contribute to abnormal hematopoiesis of MDS and may be 1 of the antioncogenes. Delta-like-1 (DLK1) is frequently expressed at elevated levels in CD34(+) cells from patients with MDS. To investigate its role in the pathogenesis of MDS, we tested bone marrow samples from a panel of patients with MDS, AML, or myeloproliferative neoplasms, with real-time polymerase chain reaction (PCR). We show here that DLK1 mRNA levels are higher in MDS patients and lower in AML patients than in healthy individuals. Myeloid progenitor 32D cells overexpressing DLK1 display increased apoptosis, reduced differentiation, and decreased cell number expansion, which is also accompanied by changes in cell cycle progression. Immortalized fibroblastic 3T3 cells can grow into tumors in nude mice but the size of tumors are smaller from those overexpressing DLK1. These observations suggest that DLK1 dysfunction may contribute to the ineffective hematopoiesis of MDS.

Diagnosis of myelodysplastic syndromes in cytopenic patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

A new recurrent chromosomal translocation t(3;11)(q13;q14) in myelodysplastic syndromes associated with overexpression of the ILDR1 gene

Myelodysplastic syndromes (MDS) are a heterogeneous group of diseases characterized by ineffective hematopoiesis and an increased risk of evolution to acute myeloid leukemia (AML). In this study, the combination of conventional cytogenetic, FISH studies and molecular techniques allowed us to unveil a novel recurrent t(3;11)(q13;q14) causing the overexpression of the immunoglobulin-like domain-containing receptor (ILDR1) gene. The analysis of gene expression was extended to Refractory Anemia (RA) and Refractory Anemia with excess blasts (RAEB) cases revealing ILDR1 overexpression in 36% of RAEB subgroup. The biological implications of the ILDR1 overexpression in MDS pathogenesis and its potential prognostic significance should be further investigated.

Predicting survival of patients with hypocellular myelodysplastic syndrome: development of a disease-specific prognostic score system

BACKGROUND

Although most patients with myelodysplastic syndrome (MDS) exhibit bone marrow hypercellularity, a subset of them present with a hypocellular bone marrow. Specific factors associated with poor prognosis have not been investigated in patients with hypocellular MDS.

METHODS

The authors studied a cohort of 253 patients with hypocellular MDS diagnosed at The University of Texas MD Anderson Cancer Center between 1993 and 2007 and a cohort of 1725 patients with hyper-/normocellular MDS diagnosed during the same time period.

RESULTS

Patients with hypocellular MDS presented more frequently with thrombocytopenia (P < .019), neutropenia (P < .001), low serum β-2 microglobulin (P < .001), increased transfusion dependency (P < .001), and intermediate-2/high-risk disease (57% vs 42%, P = .02) compared with patients with hyper-/normocellular MDS. However, no difference in overall survival was observed between the 2 groups (P = .28). Multivariate analysis identified poor performance status (Eastern Cooperative Oncology Group ≥2), low hemoglobin (<10 g/dL), unfavorable cytogenetics (-7/7q or complex), increased bone marrow blasts (≥5%), and high serum lactate dehydrogenase (>600 IU/L) as adverse independent factors for survival.

CONCLUSIONS

A new prognostic model based on these factors was built that segregated patients into 3 distinct risk categories independent of International Prognostic Scoring System (IPSS) score. This model is independent from the IPSS, further refines IPSS-based prognostication, and may be used to develop of risk-adapted therapeutic approaches for patients with hypocellular MDS.

Bone marrow mesenchymal stem cells in myelodysplastic syndromes: cytogenetic characterization

AIM

This study compared genetic aberrations in hematopoietic cells (HCs) and mesenchymal stem cells of myelodysplastic syndrome (MDS-MSCs) patients.

METHODS

We obtained chromosomes with aberrations from 22 patients with MDS and chromosomes from 7 healthy individuals. Chromosomal aberrations in both HCs and MSCs were identified using G-banding. We then performed DNA content analysis of the HCs and MSCs.

RESULTS

Cytogenetic aberrations were detected in HCs from 13 of the 22 MDS patients (59%). Chromosomal aberrations in MSCs were detected in 15 of the 22 MDS patients (68%). No chromosomal abnormalities were identified in MSCs of the 7 healthy volunteers. We demonstrate herein that MSCs have distinct genetic abnormalities compared to HCs from the same individual. We observed a random loss of chromosomal material in significant proportions of MSCs. A high proportion of random loss may be a marker of chromosomal instability of MDS-MSCs. However, two case results showed that HCs and MSCs have different altered structural changes.

CONCLUSION

Our results suggest enhanced genetic susceptibility of these cells in MDS patients. Our data indicates that the genetic alterations in MSCs may constitute a particular biological mechanism of MDS pathogenesis.

Computerized texture analysis of atypical immature myeloid precursors in patients with myelodysplastic syndromes: an entity between blasts and promyelocytes

BACKGROUND

Bone marrow (BM) blast count is an essential parameter for classification and prognosis of myelodysplastic syndromes (MDS). However, a high degree of cell atypias in bone marrow hemopoietic cells may be found in this group of clonal disorders, making it difficult to quantify precisely myeloblasts, and to distinguish them from promyelocytes and atypical immature myeloid precursors. Our aim was to investigate whether computerized image analysis of routine cytology would help to characterize these cells.

METHODS

In May-Grünwald-Giemsa stained BM smears of 30 newly diagnosed MDS patients and 19 cases of normal BM, nuclei of blasts and promyelocytes were digitalized and interactively segmented. The morphological classification of the cells was done by consensus of two observers. Immature granulocytic precursors, which could not be clearly classified either as blasts or promyelocytes, were called "atypic myeloid precursors". Nuclear morphometry and texture features derived from the co-occurrence matrix and fractal dimension (FD) were calculated.

RESULTS

In normal BM, when compared to myeloblasts, nuclei of promyelocytes showed significant increase in perimeter and local texture homogeneity and a decrease in form factor, chromatin gray levels, Haralick's entropy, inertia, energy, contrast, diagonal moment, cluster prominence, the fractal dimension according to Minkowski and its goodness-of-fit. Compared to normal myeloblast nuclei, the chromatin texture of MDS myeloblasts revealed higher local homogeneity and goodness-of-fit of the FD, but lower values of entropy, contrast, diagonal moment, and fractal dimension. The same differences were found between nuclei of normal promyelocytes and those of MDS. Nuclei of atypical myeloid precursors showed intermediate characteristics between those of blasts and promyelocytes according to the quantitative features (perimeter, form factor, gray level and its standard deviation), but were similar to promyelocytes according to the texture variables inertia, energy, contrast, diagonal moment, cluster prominence, and Minkowski's fractal dimension.

CONCLUSION

BM atypical immature myeloid precursors are difficult to be correctly classified in routine cytology. Although their cytoplasm is more similar to that of myeloblasts, computerized texture analysis indicates a nuclear chromatin remodeling more close to the promyelocyte, thus indicating an asynchronous intermediate maturation stage between blast and promyelocyte.

Mesenchymal stromal cells of myelodysplastic syndrome and acute myeloid leukemia patients have distinct genetic abnormalities compared with leukemic blasts

Mesenchymal stromal cells (MSCs) are an essential cell type of the hematopoietic microenvironment. Concerns have been raised about the possibility that MSCs undergo malignant transformation. Several studies, including one from our own group, have shown the presence of cytogenetic abnormalities in MSCs from leukemia patients. The aim of the present study was to compare genetic aberrations in hematopoietic cells (HCs) and MSCs of myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) patients. Cytogenetic aberrations were detected in HCs from 25 of 51 AML patients (49%) and 16 of 43 MDS patients (37%). Mutations of the FLT3 and NPM1 genes were detected in leukemic blasts in 12 (23%) and 8 (16%) AML patients, respectively. Chromosomal aberrations in MSCs were detected in 15 of 94 MDS/AML patients (16%). No chromosomal abnormalities were identified in MSCs of 36 healthy subjects. We demonstrate herein that MSCs have distinct genetic abnormalities compared with leukemic blasts. We also analyzed the main characteristics of patients with MSCs carrying chromosomal aberrations. In view of these data, the genetic alterations in MSCs may constitute a particular mechanism of leukemogenesis.

Myelodysplastic syndrome and histone deacetylase inhibitors: "to be or not to be acetylated"?

Myelodysplastic syndrome (MDS) represents a heterogeneous group of diseases with clonal proliferation, bone marrow failure and increasing risk of transformation into an acute myeloid leukaemia. Structured guidelines are developed for selective therapy based on prognostic subgroups, age, and performance status. Although many driving forces of disease phenotype and biology are described, the complete and possibly interacting pathogenetic pathways still remain unclear. Epigenetic investigations of cancer and haematologic diseases like MDS give new insights into the pathogenesis of this complex disease. Modifications of DNA or histones via methylation or acetylation lead to gene silencing and altered physiology relevant for MDS. First clinical trials give evidence that patients with MDS could benefit from epigenetic treatment with, for example, DNA methyl transferase inhibitors (DNMTi) or histone deacetylase inhibitors (HDACi). Nevertheless, many issues of HDACi remain incompletely understood and pose clinical and translational challenges. In this paper, major aspects of MDS, MDS-associated epigenetics and the potential use of HDACi are discussed.

Mouse models of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are hematopoietic malignancies characterized by peripheral cytopenias in the face of normo- or hypercellular, dysplastic bone marrow that arise from mutations in the hematopoietic stem/progenitor cell (HSPC). The disease is characterized by multiple cytogenetic and molecular defects, which result in an extremely heterogeneous phenotype. Recently, significant efforts have been made to develop appropriate mouse models to study this complex disease. Because of the heterogeneity of MDS, no single model is able to capture the MDS phenotype in its entirety. In this review, we describe several MDS mouse models and discuss the advances made in our understanding of the different disease mechanisms within the malignant clone and the marrow microenvironment. In addition, we describe progress in xenotransplantation models of MDS and discuss questions that remain to be answered.

Identification of a risk dependent microRNA expression signature in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) display both haematological and biological heterogeneity with variable leukaemia potential. MicroRNAs play an important role in tumour suppression and the regulation of self-renewal and differentiation of haematopoietic progenitors. Using a microarray platform, we evaluated microRNA expression from 44 patients with MDS and 17 normal controls. We identified a thirteen microRNA signature with statistically significant differential expression between normal and MDS specimens (P < 0·01), including down-regulation of members of the leukaemia-associated MIRLET7 family. A unique signature consisting of 10 microRNAs was closely associated with International Prognostic Scoring System (IPSS) risk category permitting discrimination between lower (Low/Intermediate-1) and higher risk (Intermediate-2/High) disease (P < 0·01). Selective overexpression of MIR181 family members was detected in higher risk MDS, indicating pathogenetic overlap with acute myeloid leukaemia. Survival analysis of an independent cohort of 22 IPSS lower risk MDS patients revealed a median survival of 3·5 years in patients with high expression of MIR181 family compared to 9·3 years in patients with low MIR181 expression (P = 0·002). Our pilot study suggested that analysis of microRNA expression profile offers diagnostic utility, and provide pathogenetic and prognostic discrimination in MDS.

NF-κB as a potential therapeutic target in myelodysplastic syndromes and acute myeloid leukemia

IMPORTANCE OF THE FIELD

The inactive NF-κB-inhibitor of NF-κB (IκB) complex is activated by stimuli including pro-inflammatory cytokines, mitogens, growth factors and stress-inducing agents. The release of NF-κB facilitates its translocation to the nucleus, where it promotes cell survival by initiating transcription of genes encoding stress-response enzymes, cell-adhesion molecules, pro-inflammatory cytokines and anti-apoptotic proteins. NF-κB and associated regulatory factors (IκB kinase subunits and bcl-3) are implicated in hematological and solid tumour malignancies. NF-κB appears to be involved in cell proliferation control, apoptosis control, angiogenesis promotion and possibly regulation of diffusion of metastases. There are several reports that inhibition of NF-κB as a therapeutic target may have a role in tumour cell death or growth inhibition.

AREA COVERED IN THIS REVIEW

We review data about inhibition of NF-κB in acute myeloid leukemia (AML) and myelodysplastic syndromes (MDS). We describe the molecular mechanisms underlying NF-κB deregulation in these haematological malignancies.

WHAT THE READER WILL GAIN

Constitutive activation of NF-κB in the nucleus has been reported in some varieties of MDS/AML. The in vitro and in vivo results of NF-κB inhibition in myeloid malignancies are highlighted.

TAKE HOME MESSAGE

NF-κB selective inhibitory drugs may be useful, either as single agents or associated with conventional chemotherapy.

Myelodysplastic syndromes: an update on molecular pathology

The myelodysplastic syndromes (MDS) are a heterogeneous group of myeloid disorders characterised by impaired peripheral blood cell production due to bone marrow dysplasia affecting one or more of the major myeloid cell lines. MDS are one of five major categories of myeloid neoplasms according to the World Health Organization (WHO) classification system for haematological cancers. Given their cytological and cytogenetic heterogeneity, these diseases probably constitute a group of molecularly distinct entities with variable degrees of ineffective haematopoiesis and susceptibility to leukaemic transformation. Recent studies provide some insights into the physiopathology of MDS. In the early stages, one mechanism contributing to hypercellular marrow and peripheral blood cytopenia is a significant increase in programmed cell death (apoptosis) in haematopoietic cells. Furthermore, altered responses in relation to cytokines, the immune system and bone marrow stroma also contribute to the disease phenotype. Deletions of chromosome 5q31-q32 are the most common recurring cytogenetic abnormalities detected in MDS. The 5q- syndrome is a new entity recognised in the WHO classification since 2001 and is associated with a good prognosis. Haploinsufficiency of multiple genes mapping to the common deleted region at 5q31-32 may contribute to the pathogenesis of 5q- syndrome and other MDS with 5q- deletion. Many studies have demonstrated that altered DNA methylation and histone acetylation can alter gene transcription. Abnormal methylation of transcription promoter sites is universal in patients with MDS, and the number of involved loci is increased in high-risk disease and secondary leukaemias. A better understanding of the pathogenesis of MDS can contribute to the development of new treatments such as hypomethylating drugs, immunomodulatory agents such as lenalidomide, and immunosuppressive drugs aimed at reversing the specific alteration that results in improvement in patients with MDS.

Risk of Myelodysplastic Syndromes in People Exposed to Ionizing Radiation: A Retrospective Cohort Study of Nagasaki Atomic Bomb Survivors

Purpose

The risk of myelodysplastic syndromes (MDS) has not been fully investigated among people exposed to ionizing radiation. We investigate MDS risk and radiation dose-response in Japanese atomic bomb survivors.

Patients and Methods

We conducted a retrospective cohort study by using two databases of Nagasaki atomic bomb survivors: 64,026 people with known exposure distance in the database of Nagasaki University Atomic-Bomb Disease Institute (ABDI) and 22,245 people with estimated radiation dose in the Radiation Effects Research Foundation Life Span Study (LSS). Patients with MDS diagnosed from 1985 to 2004 were identified by record linkage between the cohorts and the Nagasaki Prefecture Cancer Registry. Cox and Poisson regression models were used to estimate relationships between exposure distance or dose and MDS risk.

Results

There were 151 patients with MDS in the ABDI cohort and 47 patients with MDS in the LSS cohort. MDS rate increased inversely with exposure distance, with an excess relative risk (ERR) decay per km of 1.2 (95% CI, 0.4 to 3.0; P < .001) for ABDI. MDS risk also showed a significant linear response to exposure dose level (P < .001) with an ERR per Gy of 4.3 (95% CI, 1.6 to 9.5; P < .001). After adjustment for sex, attained age, and birth year, the MDS risk was significantly greater in those exposed when young.

Conclusion

A significant linear radiation dose-response for MDS exists in atomic bomb survivors 40 to 60 years after radiation exposure. Clinicians should perform careful long-term follow-up of irradiated people to detect MDS as early as possible.

FLT3 and NPM1 mutations in myelodysplastic syndromes: Frequency and potential value for predicting progression to acute myeloid leukemia

We reviewed FLT3 and NPM1 mutation data in a large cohort of patients with myelodysplastic syndrome (MDS). The frequencies of FLT3 and NPM1 mutation were 2.0% and 4.4%, respectively, and mutations were restricted to cases of intermediate- and high-risk MDS. Cytogenetic abnormalities were identified in 46.9% of cases. FLT3 mutations were associated with a complex karyotype (P = .009), whereas NPM1 mutations were associated with a diploid karyotype (P < .001). FLT3 mutation (P < .001) was associated with progression to acute myeloid leukemia (AML), as were a higher bone marrow (BM) blast count (P < .001) and complex cytogenetics (P = .039). No patient with an NPM1 mutation alone had disease that progressed to AML. Cox proportional regression multivariate analysis indicated that FLT3 mutation, NPM1 mutation, complex cytogenetics, BM blast count, pancytopenia, and age were independent factors that correlated with progression-free survival. We conclude that FLT3 and NPM1 mutations are rare in MDS, but assessment of mutation status is potentially useful for predicting progression to AML.

Diagnosis of Myelodysplastic Syndromes in Cytopenic Patients

Sustained clinical cytopenia is a frequent laboratory finding in ambulatory and hospitalized patients. For pathologists and hematopathologists who examine the bone marrow (BM), a diagnosis of cytopenia secondary to an infiltrative BM process or acute leukemia can be readily established based on morphologic evaluation and flow cytometry immunophenotyping. However, it can be more challenging to establish a diagnosis of myelodysplastic syndrome (MDS). In this article, the practical approaches for establishing or excluding a diagnosis of MDS (especially low-grade MDS) in patients with clinical cytopenia are discussed along with the current diagnostic recommendations provided by the World Health Organization and the International Working Group for MDS.

Erythroid response and decrease of WT1 expression after proteasome inhibition by bortezomib in myelodysplastic syndromes

NF-kB is reported to be constitutively activated in a percentage of high-risk myelodysplastic syndrome carrying cytogenetic aberrations. Only few data are reported on the use of proteasome inhibitors in this subset of patients. We performed a study on efficacy and safety of bortezomib as a single agent in patients with myelodysplastic syndromes (MDS). Bortezomib was administered at 1.3mg/m(2) with a 1, 4, 8, 11-day schedule every 28 days, in 19 patients with IPSS low/intermediate 1 or intermediate2/high risk. Six out of 19 patients received all planned eight cycles. Hematologic toxicity was recorded in all patients, especially grade 3/4 neutropenia and grade 3/4 thrombocytopenia; non-hematologic side effects were recorded in 7 patients, but events were all of grade 1/2 toxicity. According to IWG 2006 criteria, 4 out of 19 patients (21%) achieved erythroid response and 9 patients (47%) showed stable disease. In patients with erythroid response bone marrow WT1 levels decreased from a median of 109 copies at baseline to a median of 14 copies at the end of treatment, whereas in patients with stable disease, median WT1 copies increased either in bone marrow and peripheral blood. In conclusion, bortezomib used alone in MDS shows modest hematologic efficacy but appears to affect the WT1 gene expression, which is typically increased in these diseases.

Acute erythroid leukemia as defined in the World Health Organization classification is a rare and pathogenetically heterogeneous disease

The diagnostic criteria for acute erythroid leukemia have been controversial since this disease was initially described. Using the current World Health Organization classification criteria, we retrospectively reviewed cases of acute myeloid leukemia or myelodysplastic syndrome in which erythroid precursors were >or=50% of the bone marrow nucleated cell population and the diagnosis of erythroleukemia was considered using older classification schemes. We collected 90 cases and separated them into four diagnostic groups: acute erythroid leukemia, erythroleukemia or erythroid/myeloid type (n=20); acute myeloid leukemia with myelodysplasia-related changes (n=22); therapy-related acute myeloid leukemia (n=32); and refractory anemia with excess blasts and preceding or concurrent history of erythropoietin therapy for anemia (n=16). Patients with acute erythroid leukemia were the youngest patient group and had the best overall survival. There was a statistically significant difference in overall survival between patients with acute erythroid leukemia versus acute myeloid leukemia with myelodysplasia-related changes (P=0.003) and between patients with acute erythroid leukemia versus therapy-related acute myeloid leukemia (P<0.0001). The presence of complex cytogenetic abnormalities (>3) was the only statistically significant independent variable that adversely affected survival in the acute erythroid leukemia group. Monosomy 5/del(5q) and monosomy 7/del(7q) were overrepresented in the context of complex chromosomal abnormalities. Our data suggest that acute erythroid leukemia, as currently defined in the World Health Organization classification, has become a rare disease. A majority of the cases reported previously as erythroleukemia are now classified as other entities. In addition, our data suggest that the current definition of acute erythroid leukemia, erythroleukemia type remains heterogeneous. One subset of acute erythroid leukemia patients has relatively low blast counts and are diploid. The prognosis of this patient subset is relatively good. The other subset has cytogenetic abnormalities similar to those in myelodysplastic syndromes and a poor prognosis.

Does cytogenetic evolution have any prognostic relevance in myelodysplastic syndromes? A study on 153 patients from a single institution

The present study was designed to establish the incidence of cytogenetic evolution (CE), defined as the acquisition of chromosomal defects during the course of MDS, in order to correlate it with the WHO classification and IPSS score, and to assess its impact on overall survival (OS) and risk of MDS/AML evolution (progression-free interval, PFI) by means of Cox models for time-dependent covariates. Adjustments for known risk factors were achieved by performing a bivariable analysis. The study was carried out in 153 MDS patients who were followed for a median period of 45.2 months. Disease progression occurred in 42.4% of patients after a 65.2-month median PFI, while CE occurred in 30.7% of patients. Our study shows that (1) CE was more common in advanced than in early MDS, and advanced MDS presented secondary chromosomal defects distinct from those of early MDS; (2) CE significantly affected OS and PFI independently of other prognostic variables; (3) del(7)(q31q34) was the only secondary chromosomal defect which significantly affected PFI; trisomy 8 had only a moderate influence.

Prognosis of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a very complex group of hematopoietic disorders. The degree of complexity relates not only to the intrinsic pathobiological characteristics of the disease, but also to the group of patients whom it affects most frequently: older individuals or those who have been exposed to prior forms of chemotherapy. It is therefore crucial to develop clinical tools to predict with a certain degree of precision the prognosis and outcome for patients with specific subtypes of MDS in specific clinical situations. At the present time, patients with MDS are diagnosed using a set of well-established histopathological criteria. Prognosis is established using classifications that include morphological features, percentage of blasts, and clinical and molecular characteristics such as peripheral cytopenias and cytogenetics. The International Prognostic Scoring System (IPSS) is a classic example of this type of classification. Over the last 5 years, there has been an intense effort to develop new prognostic systems for MDS, and new molecular alterations with potential prognostic value have been discovered. Over the same period of time, several new therapeutic interventions have been developed for patients with MDS. Biomarkers of response to these agents, in particular for the hypomethylating agents, are needed to predict clinical benefit. This review summarizes current prognostic models of MDS and new molecular alterations with potential prognostic potential.

Core binding factor at the crossroads: determining the fate of the HSC

Hematopoietic development requires coordinated actions from a variety of transcription factors. The core binding factor (CBF), consisting of a Runx protein and the CBFbeta protein, is a transcription factor complex that is essential for emergence of the hematopoietic stem cell (HSC) from an endothelial cell stage. The hematopoietic defects observed in either Runx1 or CBFbeta knockout mice underscore the necessity of this complex for definitive hematopoiesis. Despite the requirement for CBF in establishing definitive hematopoiesis, Runx1 loss has minimal impact on maintaining the HSC state postnatally, while CBFbeta may continue to be essential. Lineage commitment, on the other hand, is significantly affected upon CBF loss in the adult, indicating a primary role for this complex in modulating differentiation. Given the impact of normal CBF function in the hematopoietic system, the severe consequences of disrupting CBF activity, either through point mutations or generation of fusion genes, are obvious. The physiologic role of CBF in differentiation is subverted to an active process of self-renewal maintenance by the genetic aberrations, through several possible mechanisms, contributing to the development of hematopoietic malignancies including myelodysplastic syndrome and leukemia. The major impact of CBF on the hematopoietic system in both development and disease highlights the need for understanding the intricate functions of this complex and reiterate the necessity of continued efforts to identify potential points of therapeutic intervention for CBF-related diseases.

Progress in myelodysplastic syndromes

During the past 5 years, we have witnessed an explosion in our understanding, classification, and number of therapeutic opportunities for patients with myelodysplastic syndromes (MDS). These include the development of new histologic classifications, scoring systems, supportive care measures, and most importantly, effective treatments that are safe and can modify the natural history of this complex group of hematopoietic disorders. In this brief review, and as part of the Leukemia 2008, Fourth International Conference, held in Houston during September 2008, I summarize some of the most important recent developments in the field of MDS and try to identify new problems and opportunities for patients and researchers in this area.

Does MDS with der(1;7)(q10;p10) constitute a distinct risk group? A retrospective single institutional analysis of clinical/pathologic features compared to -7/del(7q) MDS

The der(1;7)(q10;p10) aberration is observed in about 1-3% of the myelodysplastic syndromes (MDS) and less commonly in acute myeloid leukemia (AML) and the myeloproliferative disorders. This unbalanced translocation is considered a "variant" of the del(7q)/-7 subgroup and has been assigned a poor risk karyotype score in the MDS International Prognostic Scoring System (IPSS). Recent reports suggest der(1;7) MDS should be considered a discrete MDS subgroup with an intermediate, not poor, karyotype score. At the City of Hope, we compared the clinical-pathologic features of 12 der(1;7) MDS patients to 51 MDS patients with del(7q) (n=10) or -7 (n=41), selected for a similar frequency of secondary aberrations. The der(1;7) patients showed older age at diagnosis, lower platelet counts, less trilineage dysplasia, and lower blast counts. The der(1;7) patients did not differ from del(7q)/-7 patients in subtypes of MDS by World Health Organization, French-American-British classifications, or bone marrow cellularity. Neither the proportion of therapy-related MDS nor the transformation to AML differed significantly among the three subgroups. Five-year survival rates for der(1;7), del(7q), and -7 (44.4, 32.0, and 23.6%, respectively) did not differ significantly (P=0.94). While der(1;7) MDS is associated with some clinically distinctive features, reassignment of risk category based on these data would be premature.

Phase 1 multicenter dose-escalation study of ezatiostat hydrochloride (TLK199 tablets), a novel glutathione analog prodrug, in patients with myelodysplastic syndrome

Phase 1 testing of ezatiostat, a glutathione S-transferase P1-1 inhibitor, for the treatment of myelodysplastic syndrome was conducted in a multidose-escalation study. Patients received 10 dose levels (200, 400, 1000, 1400, 2000, 2400, 3000, 4000, 5000, and 6000 mg) of ezatiostat tablets in divided doses on days 1 to 7 of a 21-day cycle for a maximum of 8 cycles. The safety and pharmacokinetics of ezatiostat were evaluated. Forty-five patients with low to intermediate-2 International Prognostic Scoring System risk myelodysplastic syndrome were enrolled. No dose-limiting toxicities were observed. The most common grade 1 or 2, respectively, treatment-related adverse events were nonhematologic: nausea (56%, 9%), diarrhea (36%, 7%), vomiting (24%, 7%), abdominal pain (9%, 0%), constipation (4%, 9%), anorexia (3%, 7%), and dyspepsia (3%, 7%). Concentration of the primary active metabolite, TLK236, increased proportionate to ezatiostat dosage. Seventeen hematologic improvement (HI) responses by International Working Group criteria were observed at dose levels of 200 to 6000 mg/day with 11 HI responses at doses of 4000 to 6000 mg/day. HI responses occurred in all lineages including 3 bilineage and 1 complete cytogenetic response. Decreased number of red blood cell and platelet transfusions and in some cases transfusion independence were attained. Extended dose schedules of ezatiostat tablets are under investigation. This study was registered at http://www.clinicaltrials.gov as NCT00280631.

Mutations of polycomb-associated gene ASXL1 in myelodysplastic syndromes and chronic myelomonocytic leukaemia

The myelodysplastic syndromes (MDSs) are a heterogeneous group of clonal haematological diseases characterized by ineffective haematopoiesis and predisposition to acute myeloid leukaemia (AML). The pathophysiology of MDSs remains unclear. A definition of the molecular biology of MDSs may lead to a better classification, new prognosis indicators and new treatments. We studied a series of 40 MDS/AML samples by high-density array-comparative genome hybridization (aCGH). The genome of MDSs displayed a few alterations that can point to candidate genes, which potentially regulate histone modifications and WNT pathways (e.g. ASXL1, ASXL2, UTX, CXXC4, CXXC5, TET2, TET3). To validate some of these candidates we studied the sequence of ASXL1. We found mutations in the ASXL1 gene in four out of 35 MDS patients (11%). To extend these results we searched for mutations of ASXL1 in a series of chronic myelomonocytic leukaemias, a disease classified as MDS/Myeloproliferative disorder, and found mutations in 17 out of 39 patients (43%). These results show that ASXL1 might play the role of a tumour suppressor in myeloid malignancies.