Epidemiological and etiological aspects of myelodysplastic syndromes

Trends of classification, incidence, mortality, and survival of MDS patients in Switzerland between 2001 and 2012

Myelodysplastic syndromes (MDS) are emerging disorders of the elderly with an increasing burden on healthcare systems. He we report on the first population-based, epidemiological analysis of patients diagnosed with MDS in Switzerland between 2001 and 2012. The aim of this study was to characterize the extent and limitations of currently available population-based, epidemiological data and formulate recommendations for future health services research. The investigated outcomes comprised trends of annual case frequency, classification of morphological subtypes, incidence, mortality and survival. Annual case frequency increased by 20% (from 263 to 315 cases per year), whereas age-standardized incidence-/mortality-rates remained stable (2.5/1.1 per 100'000 person-years). This observation reflects population growth as well as higher diagnostic awareness and not an increase of age-specific risk. However, it will inevitably influence the future prevalence of MDS and the impact on healthcare systems. Reporting of classification in MDS subtypes was poor with modest improvement from 20% to 39% and increased awareness for mainly higher-risk diseases. Relative survival for all patients at 5-years (RS) ranged between 37 and 40%. Significant better RS was found for younger compared to older higher-risk MDS patients (48% vs. 17%), reflecting the effect of allogeneic hematopoietic stem-cell transplantation. However, no survival advantage was found in elderly patients after introduction of hypomethylating agents as standard for care in this patient group. Our data is in line with results from other MDS and cancer registries. It allows formulating recommendations for future collaborative health services research on MDS patients with national and international partners.

Recurrent Abnormal Clones in Myelodysplastic Syndrome Marrow Originate from Cells at a Pluripotent Stem Level and Maintain Their Early Differentiation Potency

OBJECTIVE

The present study aimed to investigate the origins and differentiation potencies of 4 common malignant clonal cell types (+8, 5q-/-5, 20q-/-20, 7q-/-7) in myelodysplastic syndrome (MDS) and to investigate whether the trisomy of chromosome 8 occurs subsequently to other chromosomal abnormalities.

METHODS

The present study analyzed a total of 46 cases of chromosomal abnormalities in MDS patients. The magnetic activated cell sorting technique (MACS) was used to sort the CD34(+)CD38(-) (pluripotent hematopoietic stem cells) and CD34(+)CD38(+) cells (committed progenitor cells) from the bone marrow mononuclear cells (BMNCs) of these patients; the sorted cells were then individually smeared. Meanwhile, cytospins were prepared from the remaining CD34(-) BMNCs after cell sorting. The clonal cell proportions in these three types of smears were detected by fluorescence in situ hybridization (FISH). Cases in which +8 was associated with another abnormality (2 cases each in combination with abnormalities in chromosomes 7, 5, and 20) were dually hybridized with the cep8 probe and another corresponding probe.

RESULTS

(1) for abnormalities of +8, 5q-/-5, 20q-/-20 or chromosome 7 involvements, clonal cells above the baseline level were detected in the pluripotent stem cell level. (2) The average clonal cell proportion in the committed progenitor cells of the 46 cases increased to 75.3% from 57.3% at the level of stem cell (p < 0.001). The groups with +8 and chromosome 5 abnormalities showed a statistically significant increase in clonal cells at the progenitor cell stage. At the individual level, 33 of 46 cases showed significant increases in clonal cells at the progenitor cell stage relative to the stem cell stage, whereas the clonal cell proportion in the CD34(-) BMNCs generally did not increase relative to the committed progenitor cell population. (3) The dual hybridization analysis showed that if +8 and another abnormality were present in the same abnormal clone according to G-banding, +8 always coexisted with the other chromosomal abnormality at the single cell level; there were no situations in which +8 occurred later than the other chromosomal abnormality.

CONCLUSION

It seems that the all malignant MDS clones originated at the pluripotent hematopoietic stem cell stage and that the proliferation and differentiation potencies were retained partly in these clonal cells. The present study failed to confirm that the trisomy 8 occurred subsequently to the other abnormalities, but some in vitro or transplant experiments maybe prove the succession of clonal origination.

What's all the fuss about? facts and figures about bone marrow failure and conditions

The epidemiology of bone marrow failure conditions is not well understood. Although several population-based studies conducted in the last two decades have generated a wealth of information, it is still very challenging to interpret disease incidence and prevalence, particularly due to changes in disease classification, misdiagnosis of patients, frequent underreporting and use of different referent populations to calculate rates. Despite these limitations, the available epidemiologic data have revealed significant ethnic, geographic and clinical differences in disease biology that have implications for prevention and treatment strategies. With advances made in targeted therapies facilitated by identification of molecular biomarkers and increased use of curative bone marrow transplantation approach, the natural history of these disease entities is already changing. The epidemiology of these diseases seems to be the next frontier as knowledge gained about the risk factors and pathobiologic correlates could significantly help in designing patient-specific therapies with improved outcomes.

Human blood and marrow side population stem cell and Stro-1 positive bone marrow stromal cell numbers decline with age, with an increase in quality of surviving stem cells: correlation with cytokines

Hematological deficiencies increase with aging leading to anemias, reduced hematopoietic stress responses and myelodysplasias. This study tested the hypothesis that side population hematopoietic stem cells (SP-HSC) would decrease with aging, correlating with IGF-1 and IL-6 levels and increases in bone marrow fat. Marrow was obtained from the femoral head and trochanteric region of the femur at surgery for total hip replacement (N=100). Whole trabecular marrow samples were ground in a sterile mortar and pestle and cellularity and fat content determined. Marrow and blood mononuclear cells were stained with Hoechst dye and the SP-HSC profiles acquired. Marrow stromal cells (MSC) were enumerated flow cytometrically employing the Stro-1 antibody, and clonally in the colony forming unit fibroblast (CFU-F) assay. Plasma levels of IGF-1 (ng/ml) and IL-6 (pg/ml) were measured by ELISA. SP-HSC in blood and bone marrow decreased with age but the quality of the surviving stem cells increased. MSC decreased non-significantly. IGF-1 levels (mean=30.7, SEM=2) decreased and IL-6 levels (mean=4.4, SEM=1) increased with age as did marrow fat (mean=1.2mmfat/g, SEM=0.04). There were no significant correlations between cytokine levels or fat and SP-HSC numbers. Stem cells appear to be progressively lost with aging and only the highest quality stem cells survive.

Myelodysplastic syndromes: biology and treatment

Optimal management of patients with myelodysplastic syndromes (MDS) requires an insight into the biology of the disease and the mechanisms of action of the available therapies. This review focuses on low-risk MDS, for which chronic anaemia and eventual progression to acute myeloid leukaemia are the main concerns. We cover the updated World Health Organization classification, the latest prognostic scoring system, and describe novel findings in the pathogenesis of 5q- syndrome. We perform in depth analyses of two of the most widely used treatments, erythropoietin and lenalidomide, discussing mechanisms of action, reasons for treatment failure and influence on survival.

Epidemiology of myelodysplastic syndromes

Myelodysplastic syndromes (MDS) are one of the most common hematological conditions among the elderly. Differences in disease classification and diagnosis have made population-based studies an arduous endeavor. A variety of risk factors have been linked with increased risk (smoking and exposure to solvents and agrochemicals) or decreased risk of MDS (wine drinking), but the majority of cases remain unexplained. One area that has not been explored is the influence of diet in MDS development. Much still needs to be learned about what causes MDS and the genetic factors that increase susceptibility. Multi-institutional studies with a molecular-epidemiologic approach are necessary to develop a MDS risk predictive model.

Reduced-intensity conditioning for allogeneic hematopoietic stem cell transplantation with fludarabine and melphalan is associated with durable disease control in myelodysplastic syndrome

We retrospectively evaluated the outcome of reduced-intensity conditioning (RIC) followed by allogeneic hematopoietic stem cell transplantation (HCT) in 43 patients with myelodysplastic syndrome (MDS) or AML arising from MDS. All patients received fludarabine plus melphalan followed by an allogeneic HCT from an HLA-identical sibling (SIB: n=19) or unrelated donor (MUD: n=24). Median age was 58 years (range: 30-71). Diagnoses at transplantation were RA (n=8), RARS (n=1), RAEB (n=13), RAEB-T (n=6), or AML arising from MDS (n=15). Of 28 patients with MDS, two patients had low, 10 had intermediate-1, nine had intermediate-2 and seven had high-risk MDS by IPSS criteria. All patients initially engrafted with the median neutrophil recovery of 15 days (range: 9-27). The 2-year overall survival, disease-free survival, relapse and transplant-related mortality were 53.5% (CI 45.2-61.1), 51.2% (CI 43.3-58.5), 16.3% (CI 7.9-30.7) and 35.2% (26.4-45.7), respectively. Grade II-IV acute graft-versus-host disease occurred in 27 (63%) patients. There was no significant survival difference between SIB and MUD-HCT, but the relapse rate was higher among SIB donor recipients when compared to MUD (38.5 versus 7%, P=0.02). RIC with fludarabine plus melphalan was associated with durable disease control and acceptable toxicity in this high-risk cohort.

The spectrum of myelodysplastic syndromes post-solid organ transplantation: A single institutional experience

An increased incidence of acute myeloid leukemia (AML) has recently been documented in patients post-solid organ transplantation but the incidence and types of myelodysplastic syndromes (MDS) occurring in this patient population are not known. We identified 5 patients (3M, 2F, age 48-64 years) who developed MDS ranging from 1.8 to 25 years (median 4.2 years) post-solid organ transplantation, only 2 patients had received azathioprine. The cumulative incidence of MDS in heart and lung transplant recipients at 15 years was 0.5% and 1.8%, respectively, which is markedly higher compared to the general population. Low-risk types of MDS predominated, 3 of 5 patients are alive (median 3.9 years) since diagnosis. Deletions of chromosome 20q, which have not been previously reported in post-transplant MDS/AML, were identified in 3 cases. Our findings expand the morphologic and cytogenetic spectrum of MDS occurring post-solid organ transplantation and suggest that mechanisms beside azathioprine toxicity might be important in disease pathogenesis.

Cytogenetic aspects of adult primary myelodysplastic syndromes: Clinical implications

Myelodysplastic syndrome (MDS) is a heterogeneous disease from the clinical, biological and morphological point of view. The pathogenesis of MDS is not well established and it appears to occur complex changes in the stem cell biology. Clonal chromosomal aberrations are found in 30-50% of primary MDS and no specific cytogenetic abnormality has as yet been defined. The chromosomal abnormalities are predominantly characterized by partial/total chromosomal losses or chromosomal gains. These chromosomal abnormalities include mainly -5/del(5q), -7/del(7q), del(11q), del(12p), del(20q), -Y, and +8. The role of cytogenetic analysis in the diagnosis, prognosis, taking treatment decisions and follow up of patients with MDS has been clearly defined. Despite its difficulties in obtaining for analysis high quality metaphases conventional cytogenetics continues to be the basic technique for cytogenetic evaluation of a MDS patient. Other molecular cytogenetic methods have been shown to be complementary, without replacing the information obtained with this technique. Further investigations with both conventional and molecular cytogenetics in relation to clinical features as well as other molecular methods will undoubtedly contribute to improve understanding of the underlying genetic events responsible for the development and evolution of MDS leading to more accurate classification and management of MDS patients.

5-azacytidine and decitabine monotherapies of myelodysplastic disorders

OBJECTIVE

To review and differentiate the pharmacology, toxicology, pharmacokinetics, and results of major clinical trials of 5-azacytidine (5-AzaC) and 5-aza-2'-deoxycytidine (decitabine) therapy of myelodysplastic disorders.

DATA SOURCES

A PubMed/MEDLINE search was conducted (1966-October 2004) using the following terms: DNA methylation, myelodysplastic disorders, 5-azacytidine, and 5-aza-2'-deoxycytidine (decitabine). Additional data sources included bibliographies from identified articles and manufacturer information.

STUDY SELECTION AND DATA EXTRACTION

Clinical trials for the treatment of various malignancies by hypomethylating agents were selected from data sources. All published, major clinical trials evaluating 5-AzaC or decitabine in myelodysplastic disorders and transformed myeloid leukemia treatment were included.

DATA SYNTHESIS

Myelodysplastic disorders are a group of bone marrow stem cell hyperplasias and dysplasias that result in ineffective hematopoiesis. Myelodysplastic disorders and transformed leukemia have poor prognosis and minimal response to chemotherapy. DNA hypomethylating agents have been shown to improve overall response rates (increased neutrophil, leukocyte, and platelet counts), time to leukemic progression, and quality of life compared with supportive therapy. The incidence of the most common adverse effects (nausea, vomiting, myelosuppression) can be reduced by low-dose, continuous, or extended-interval infusion.

CONCLUSIONS

Since appropriate dosing schedules of decitabine are being investigated, comparison of the clinical effectiveness of 5-AzaC and decitabine would be premature at this time. DNA hypomethylating agents show promise as monotherapies of myelodysplastic disorders and transformed leukemia and may be useful as a component of combination chemotherapy of various malignancies.

Myelodysplastic syndromes in patients under 50 years old: a single institution experience

We report on our experience relating to 62 patients with myelodysplastic syndrome (MDS) aged less than 50 years, seen at our Institution and conservatively treated from July 1983 to December 2000. Patients demographics and clinical features at diagnosis were analysed for their prognostic value on survival and on risk of transformation to acute leukaemia. The median age at diagnosis was 43 years (range 21-50). According to FAB criteria there were 30 patients with refractory anaemia (RA), 3 with refractory anaemia with ringed sideroblasts (RARS), 18 with refractory anaemia with excess of blasts (RAEB), 6 with refractory anaemia with excess of blasts in transformation (RAEB-t) and 5 with chronic myelomonocytic leukaemia (CMML). Fifty patients had evaluable cytogenetic analysis: the most frequent karyotypic change was trisomy of chromosome 8 (10%), followed by monosomy 7 (6%); partial chromosome deletions and translocations were also common abnormalities, occurring on the whole in 16% of patients. At a median follow-up of 15 months 19 patients (31%) progressed to acute myeloid leukaemia (AML). From univariate analysis we identified some features, which appeared to be predictive of outcome and risk of transformation to AML. Age above 40 years (p = 0.002) and high risk according to IPSS score (p = 0.002) were found to be predictive for a shorter survival; FAB grouping (p = 0.0001), percentage > 5% of blasts in the bone marrow (p = 0.001) and high risk by IPSS score (p = 0.0003) were found to be predictive for a higher risk of transformation to AML. Presenting features in young MDS patients may identify subjects at higher risk of unfavourable outcome.

Novel therapies for myelodysplastic syndromes

BACKGROUND

The assessment of patients with myelodysplastic syndromes (MDS) and the choice of therapies remain challenging. New therapies are now emerging after the identification of molecular targets that result in improvement of hematologic parameters and may hold promise for the prevention of disease progression.

METHODS

A review of the English literature was performed that included original articles and related reviews from MEDLINE (PubMed) and abstracts based on published meeting material.

RESULTS

MDS is a heterogeneous group of disorders. Although current classification and prognostic schemes have proven valid to define subgroups, they are insufficient to take into consideration the significant biologic diversity of MDS. New molecular targets are identified as the mosaic of pathophysiologic pathways in MDS is being unraveled. Novel and targeted therapeutic agents, such as the inhibition of farnesyl transferases and receptor tyrosine kinases, more potent thalidomide analogs, and arsenic trioxide, have shown encouraging results and may offer durable benefit to patients with MDS.

CONCLUSIONS

Although progress has been made in the understanding of clinical manifestations and some of the molecular pathways underlying ineffective hematopoiesis and leukemic transformation in MDS, intensive clinical and laboratory research continues to 1) identify further relevant pathophysiologic pathways, 2) better define MDS subgroups, and 3) develop new drugs based on a clearer understanding of disease biology.

Update on myelodysplastic syndromes: New approaches to classification and therapy

Myelodysplastic syndromes have long provided hematologists with difficult therapeutic challenges, and until recently treatment options beyond supportive care were limited. Recent advances in our understanding of hematopoiesis, immunology, and genetics have led to a better understanding of the natural history of these disorders and have facilitated development of more rational and targeted treatment approaches. A number of promising agents are in various phases of study, including arsenic trioxide, CC5013, the farnesyltransferase inhibitors, and DNA methyltransferase inhibitors. In addition, less intensive strategies for allogeneic stem cell transplantation now permit us to offer potentially curative therapy to a larger proportion of patients. Optimal management of an individual patient requires consideration of the disease and its expected course, available treatment options, the patient's age and condition, and an ongoing assessment of the goals of therapy.

Comparison of interphase FISH and metaphase cytogenetics to study myelodysplastic syndrome: an Eastern Cooperative Oncology Group (ECOG) study

Cytogenetic analysis can be important in determining the prognosis and diagnosis of a number of hematological disorders, including myelodysplastic syndromes (MDS). Here, we compared metaphase chromosomal analyses on bone marrow aspirates from MDS patients with interphase fluorescence in situ hybridization (FISH) using probes specific for chromosomes nos. 5, 7, 8, 11, 13 and 20. Forty-three patients enrolled in ECOG protocol E1996 for low risk MDS and five patients enrolled in ECOG protocol E3996 for high risk MDS were studied by both metaphase chromosomal analysis and interphase FISH. Excluding those with a clonal loss of the Y chromosome, an abnormal clone was detected by cytogenetic analysis in 18 of 48 samples (37.5%). In comparison, our FISH panel detected an abnormal clone in 17 of 48 samples (35.4%). Twenty-nine of 30 samples with apparently normal karyotypes, including those with a missing Y chromosome, were also normal by our FISH panel. One patient had an occult deletion of chromosome 11 that was detected by FISH. These results indicate that around 60% of patients with MDS do not have abnormalities that are detectable by either chromosomal or FISH studies. In addition, it appears that interphase FISH studies are nearly as sensitive as cytogenetic analyses and can be a useful tool in studying bone marrow aspirates where cytogenetic analysis is not possible.

[Biologic and clinical relevance of cytogenetic analysis in primary myelodysplastic syndromes]

Cytogenetic abnormalities in myelodysplastic syndromes (MDS) are complex and heterogeneous. The most frequent rearrangements (gains or losses of genetic material) vary from patient to patient, and within the same patient. The prognostic value of these rearrangements has been extensively studied. They allowed the definition of a risk based classification system for MDS (the International Scoring System for evaluating Prognosis, IPSS), proven to be a highly useful method for evaluating prognosis in MDS patients. Despite recent progress in mapping and definition of minimally deleted chromosomal regions, the primary critical genetic events remain to be determined. The recurrent cytogenetic abnormalities associated with MDS are likely to be secondary events contributing to but not initiating the neoplastic phenotype of the disease.

The myelodysplastic syndrome(s): a perspective and review highlighting current controversies

The myelodysplastic syndrome (MDS) includes a diverse group of clonal and potentially malignant bone marrow disorders characterized by ineffective and inadequate hematopoiesis. The presumed source of MDS is a genetically injured early marrow progenitor cell or pluripotential hematopoietic stem cell. The blood dyscrasias that fall under the broad diagnostic rubric of MDS appear to be quite heterogeneous, which has made it very difficult to construct a coherent, universally applicable MDS classification scheme. A recent re-classification proposal sponsored by the World Health Organization (WHO) has engendered considerable controversy. Although the precise incidence of MDS is uncertain, it has become clear that MDS is at least as common as acute myelogenous leukemia (AML). There is considerable overlap between these two conditions, and the former often segues into the latter; indeed, the distinction between AML and MDS can be murky, and some have argued that the current definitions are arbitrary. Despite the discovery of several tantalizing pathophysiological clues, the basic biology of MDS is incompletely understood. Treatment at present is generally frustrating and ineffective, and except for the small subset of patients who exhibit mild marrow dysfunction and low-risk cytogenetic lesions, the overall prognosis remains rather grim. In this narrative review, we highlight recent developments and controversies within the context of current knowledge about this mysterious and fascinating cluster of bone marrow failure states.

Myelodysplastic syndrome

The last decade has witnessed a multistep evolution in the understanding of the natural history, clinical manifestations, and some of the molecular mechanisms that underlie the ineffective hematopoiesis and leukemic transformation in the myelodysplastic syndrome (MDS). The international prognostic scoring system, FAB, and WHO classifications have helped define specific subgroups with their characteristic cytogenetic, molecular and immunological abnormalities. Until recently the mainstay of the treatment has been entirely supportive with blood and platelet transfusions. What is increasingly manifest now is the considerable excitement generated by the emergence of novel therapeutic strategies based on painstaking research findings from the laboratories. In Section I, Dr. Alan List reviews the therapeutic strategies with the specific emphasis on the relevance of molecular mechanism of apoptosis and targeted therapies using small molecules. Of particular interest is the excitement surrounding the clinical benefit obtained from potent immunomodulatory derivative (IMiD) of thalidomide CC5013. The review provides an update of the role of small molecule inhibitors of VEGF receptor tyrosine kinase, arsenic trioxide, oral matrix metalloprotease inhibitors, farnesyl transferase inhibitors, and imatinib mesylate in the treatment of MDS subgroups. In Section II, Dr. Steven Gore describes the results of clinical trials of inhibitors of DNA methylation such as 5 azacytidine (5 AC) and 5-aza 2-deoxycytidine (Decitabine). The review also provides an update on the rationale and results obtained from the combination therapy using histone deacetylases (HDAC) and DNA methyltransferase inhibitors in the treatment of MDS. In Section III, Professor Ghulam Mufti and Dr. Aloysius Ho describe the role of bone marrow transplantation with particular emphasis on recent results from reduced-intensity conditioned transplants, exploiting the graft versus leukemia effect without significant early treatment-related mortality. The section provides an update on the results obtained from the manipulation of the host's immune system with immunosuppressive agents such as ALG and/or cyclosporine A.

Expression and prognostic significance of Bcl-2 family proteins in myelodysplastic syndromes

Excessive apoptosis is implicated in the pathogenesis of myelodysplastic syndromes (MDS). We assessed by flow cytometry the expression of several members of the Bcl-2 family in bone marrow mononuclear cells (BMMNC) of 168 MDS samples at diagnosis. The proteins studied were Bcl-2, Bcl-xL (anti-apoptotic), Bax, Bad, Bak, and Bcl-xS (pro-apoptotic). The percentage of BMMNC expressing Bcl-2 and Bcl-xL was higher in refractory anemia with excess of blasts (RAEB), RAEB in transformation (RAEB-T), and chronic myelomonocytic leukemia (CMML) than in refractory anemia (RA) and RA with ringed sideroblasts (RAS). Conversely pro-apoptotic proteins Bad, Bak, and Bcl-xS were detected in a higher percentage of cells in RA and RAS. RA and RAS were associated with an increased Bcl-xS/Bcl-xL ratio. The expression of anti-apoptotic proteins was also correlated with that of CD34 and P170 and with the percentage of blast cells. Two-color analyses demonstrated that CD34 and Bcl-2 were usually expressed in the same cells. No significant correlation was found with cytogenetic abnormalities. Higher expression of pro-apoptotic Bcl-2-family proteins (Bak, Bad, Bcl-xS) and higher Bcl-xS/Bcl-xL ratio were associated with longer survival and decreased risk of leukemic transformation in univariate analysis, whereas expression of anti-apoptotic proteins was associated with decreased survival. Consequently Bcl-2 proteins expression was well correlated with the International Prognostic Scoring System (IPSS). Our data confirm that the control of apoptosis is deregulated in MDS cells. Moreover, the study of markers such as CD34 (or Bcl-2), Bcl-xL, and Bcl-xS provides additional prognostic information.

Primary myelodysplastic syndrome with normal cytogenetics: utility of 'FISH panel testing' and M-FISH

The myelodysplastic syndromes (MDS) are a clinically heterogeneous group of hematologic disorders. Cytogenetic analysis is crucial as it can provide both diagnostic and prognostic information. Herein, 32 cytogenetically normal patients with primary MDS were analyzed both by multiple FISH probes on interphase nuclei (FISH panel testing) and by M-FISH (metaphase nuclei). One patient had a chromosome 13q-arm deletion, while the remaining 31 patients had normal results. These findings confirm standard cytogenetics as an excellent technique in identifying the common chromosomal abnormalities associated with MDS and suggest limited utility for either a FISH panel test or M-FISH in primary MDS.

Clonality in the myelodysplastic syndromes

The myelodysplastic syndromes (MDSs) comprise a heterogeneous group of stem cell disorders involving cytopenia and dysplastic changes in 3 hematopoietic lineages. Although it is accepted that MDS is a clonal disorder, the exact nature of the involvement of multipotent stem cells and progenitor cells has not been resolved. Most clonality studies of MDS support the proposal that the primary neoplastic event occurs, in most patients, at the level of a committed myeloid progenitor cell, capable of differentiation into multiple myeloid lineages. The extent of the involvement of T and B lymphocytes in MDS remains controversial. Much of the variation reported may result from disease heterogeneity and technical issues such as skewed methylation patterns occurring in studies analyzing X-chromosome inactivation patterns (XCIP) and possible impurities in lymphocyte preparation. A great deal of the evidence in support of T-lymphocyte involvement in MDS has been generated by XCIP studies, and some of these data need to be treated with caution, especially data from studies in which appropriate controls were omitted. In contrast, B-lymphocyte involvement in some patients with MDS is based on studies using more robust technology including combined immunophenotyping and fluorescence in situ hybridization. Clonality studies involving myeloid and lymphoid cells in MDS have yielded discrepant results with regard to the potential involvement of multipotent (lympho-myeloid) hematopoietic stem cells (HSCs). However, failure to detect a clonal marker in all cells of all lineages does not preclude multipotent-HSC involvement. Some recent studies have produced compelling evidence to show that, in some patients with MDS, the multipotent HSC is the target of the primary neoplastic event. It now seems probable that MDS arises in multipotent HSCs more commonly than previously recognized. Such data not only provide important new insights into the biology of MDS but also may have therapeutic implications. The determination of whether multipotent HSCs are involved in the MDS clone may be important for the use of autologous stem cell transplantation in these patients.

Phase II study of combination human recombinant GM-CSF with intermediate-dose cytarabine and mitoxantrone chemotherapy in patients with high-risk myelodysplastic syndromes (RAEB, RAEBT, and CMML): an Eastern Cooperative Oncology Group Study

A Phase II study of GM-CSF with intermediate-dose cytarabine and mitoxantrone was conducted in patients with high-risk myelodysplastic syndrome. It was designed to evaluate if priming with growth factor could increase the efficiency of chemotherapy. In this older population only two of 10 patients achieved a bone marrow CR, including one patient whose leukemic blasts had an "S" phase increase of 2.55x at 48 hr. Unexpected hepatotoxicity was noted. This regimen cannot be recommended for this elderly population of patients.

Intensive treatment strategies in patients with high-risk myelodysplastic syndrome and secondary acute myeloid leukemia

Stem cell transplantation may lead to prolonged disease-free survival in young patients with high-risk myelodysplastic syndrome (MDS) and secondary acute myeloid leukemia. About one-third of patients transplanted with an HLA-identical family donor will experience long-term disease-free survival. Outcome appears to be better for younger patients, patients with less advanced stages of MDS and treatment early in the course of the disease. The results of transplantation using partially matched family donors and phenotypically matched voluntary unrelated donors are still unsatisfactory, mainly due to significantly higher transplantation related mortality rate. For patients lacking a suitable sibling donor autologous stem cell transplantation may constitute an alternative. The presence of sufficient residual polyclonal stem cells and achieving a complete remission after chemotherapy forms a prerequisite for a successful transplantation. Further development of accurate prognostic classification systems will allow a risk-adapted strategy for an individual patient.

Transcription mapping of the 5q- syndrome critical region: cloning of two novel genes and sequencing, expression, and mapping of a further six novel cDNAs

The 5q- syndrome is a myelodysplastic syndrome with the 5q deletion ¿del(5q) as the sole karyotypic abnormality. We are using the expressed sequence tag (EST) resource as our primary approach to identifying novel candidate genes for the 5q- syndrome. Seventeen ESTs were identified from the Human Gene Map at the National Center for Biotechnology Information that had no significant homology to any known genes and were assigned between DNA markers D5S413 and D5S487, flanking the critical region of the 5q- syndrome at 5q31-q32. Eleven of the 17 cDNAs from which the ESTs were derived (65%) were shown to map to the critical region of the 5q- syndrome by gene dosage analysis and were then sublocalized by PCR screening to a YAC contig encompassing the critical region. Eight of the 11 cDNA clones, upon full sequencing, had no significant homology to any known genes. Each of the 8 cDNA clones was shown to be expressed in human bone marrow. The complete coding sequence was obtained for 2 of the novel genes, termed C5orf3 and C5orf4. The 2.6-kb transcript of C5orf3 encodes a putative 505-amino-acid protein and contains an ATP/GTP-binding site motif A (P loop), suggesting that this novel gene encodes an ATP- or a GTP-binding protein. The novel gene C5orf4 has a transcript of 3.1 kb, encoding a putative 144-amino-acid protein. We describe the cloning of 2 novel human genes and the sequencing, expression patterns, and mapping to the critical region of the 5q- syndrome of a further 6 novel cDNA clones. Genomic localization and expression patterns would suggest that the 8 novel cDNAs described in this report represent potential candidate genes for the 5q- syndrome.

Malignant hematopoietic cell lines: in vitro models for the study of myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are clonal myeloid disorders characterized by bone marrow cell dysplasia and ineffective hematopoiesis leading to peripheral refractory cytopenias. The course of the disease ranges from a chronic status with progressively impaired hematopoiesis to rapid evolution to acute myeloid leukemia (AML). A panel of continuous malignant hematopoietic cell lines has been established from the whole spectrum of MDS variants and also from the different stages of the diseases, namely from the MDS phase or the overt leukemia post-MDS phase. Ten cell lines were derived from the various MDS subtypes; 17 cell lines were established from patients with leukemia (mainly AML) post-MDS. While most cell lines display myelocytic, monocytic or erythroid features, some cell lines carry lymphoid characteristics (precursor B-cell, B-cell, or T-cell), With regard to these lymphoid MDS-derived cell lines, more detailed authentication (prove of derivation from the assumed patient) and verification (prove of the malignant nature of the cell line and derivation from the assumed neoplastic cells) are required to validate the cell lines as true in vitro representatives of MDS and to exclude any cross-contamination with other cells or immortalization of normal bystander cells. On the other hand, lymphoid MDS-derived cell lines may attest to the clonal nature of MDS which may afflict progenitor cells giving rise to lymphoid or myelomonocytoid cells. Many of the MDS-derived cell lines carry cytogenetic and molecular genetic abnormalities typically associated with MDS: gain or loss of all or parts of chromosomes 5, 7, 8 and 20 (-5/5q-, -7/7q-, + 8, 20q-); alterations of oncogenes and tumor suppressor genes (IRF-1, p15, p16, p53, RAS, RB). In summary, the present panel of cell lines provides continuously growing cells and thus unlimited cell material for use as in vitro paradigms covering the whole spectrum of MDS-related hematopoetic malignancies. Properly authenticated and verified MDS-derived cell lines which should be made freely available will represent important research tools for the study of MDS biology.

Concurrent inflammatory bowel disease and myelodysplastic syndromes

Myelodysplastic syndromes (MDS) may be associated with inflammatory bowel disease (IBD). We characterized the clinical features and outcomes of patients with concurrent IBD and MDS. Using a diagnostic index, we identified all patients with both IBD and MDS at our center between 1976 and 1997. We also calculated an incidence rate of MDS in IBD using population-based data from Olmsted County, Minnesota, between 1950 and 1993. Among approximately 15,000 IBD patients seen, 25 (approximately 0.17%) were diagnosed with MDS. Fourteen had Crohn's disease and 11 had ulcerative colitis. The median age at diagnosis of IBD, particularly Crohn's disease, was higher than expected. Median age at diagnosis of MDS was typical. All but one ulcerative colitis patient was diagnosed before the diagnosis of MDS, while one-half of Crohn's disease patients were diagnosed with both ailments simultaneously. Five patients who had been diagnosed with IBD first were persistently anemic for at least 1 year prior to diagnosis of MDS. Two Crohn's disease patients had received purine analogs in the past. Median follow-up after MDS diagnosis was 1 year. Seven patients died, including two who progressed to acute myeloid leukemia. The incidence rate of MDS in IBD based on Olmsted County data was 0 cases per 100,000 person-years (95% CI, 0-55.2). The seemingly high frequency of myelodysplastic syndromes in a large referral-based group of patients with IBD suggests an association; however, an increased risk of MDS was not observed in a small regional cohort of IBD patients. Patients with MDS are diagnosed with concurrent IBD at an age older than expected. Simultaneous diagnoses were made in one-half of Crohn's disease patients. MDS should be considered in the differential diagnosis of anemia in IBD patients.

Paroxysmal nocturnal haemoglobinuria clones in patients with myelodysplastic syndromes

Among acquired stem cell disorders, pathological links between myelodysplastic syndromes (MDS) and aplastic anaemia (AA), and paroxysmal nocturnal haemoglobinuria (PNH) and AA, have been often described, whereas the relationship between MDS and PNH is still unclear. We analysed blood cells of patients with MDS to determine the incidence of the PNH clone, and analysed the PIG-A gene to find mutations characteristic of the PNH clone in MDS. In four (10%) of 40 patients with MDS, flow cytometry showed affected erythrocytes and granulocytes negative for decay-accelerating factor (DAF) and CD59. The population of affected erythrocytes was smaller in MDS patients with PNH clone (MDS/PNH) than in patients with de novo PNH, and haemolysis was milder in the MDS/PNH patients. PIG-A mutations were found in granulocytes of all patients with MDS/PNH. In type and site, the PIG-A mutations were heterogeneous, similar to that observed in de novo PNH; i.e. no mutation specific to MDS/PNH was identified. Of note, three of four patients with MDS/PNH each had two PNH clones with different PIG-A mutations, suggesting that PIG-A is mutable in patients with MDS/PNH. In a MDS/PNH patient with trisomy 8, FISH detected a distinct karyotype in a portion of granulocytes with PNH phenotype, indicating that PNH and MDS partly shared affected cells. Thus, MDS predisposes to PNH by creating conditions favourable to the genesis of PNH clone. Considering the increasing prevalence and incidence of MDS, these disorders could be useful for investigating the mechanism by which PIG-A mutation is induced.

Increasing incidence of myelodysplastic syndromes: real or fictitious?

Over the past 10-20 years, there has been a growing interest in the myelodysplastic syndromes (MDS). Due to difficulties of diagnosis, classification and case recording, the epidemiological features of MDS are still poorly defined. Recently, a number of cancer registries have published data on the regional occurrence of MDS, suggesting that MDS are much more common than previously thought. The crude incidence of MDS in these studies was 3.5-12.6 per 100,000 population per year. In people over the age of 70 years, incidence rates varied between 15 and 50 per 100,000 per year. Contrary to the assumption of most hematologists, cancer surveys usually failed to demonstrate a rising incidence of MDS. In those studies showing a significant increase in MDS, the rising number of cases was probably due to increased physician awareness and extended use of invasive diagnostic procedures in elderly people. Differences in incidence figures between regional studies may be attributed to several causes, including regional variations in disease incidence, small and ill-defined reference populations, bias due to patient referral patterns, varying intensity of diagnostic procedures and different observation periods. Because of the paucity of clinical symptoms and insignificance of morphological bone marrow changes particularly in early stage MDS, the currently available incidence figures are likely to underestimate the true incidence of MDS. Large-scale epidemiological studies are required for obtaining truly representative statistics on the incidence and prevalence of the MDS. In industrialized countries, a dramatic increase in these disorders can be expected over the next few decades due to the 'greying' of the population.

Thrombopoietin level in young patients is related to megakaryocyte frequency and platelet count

PURPOSE

To examine the relationships among platelet counts, bone marrow megakaryocyte frequency, and circulating thrombopoietin (TPO) levels.

PATIENTS AND METHODS

TPO levels in 17 children and one young adult with chronic or recurrent thrombocytopenia were measured by ELISA and megakaryocyte frequency was analyzed by light microscopy. Three groups of patients were studied: Group I patients had aplastic anemia and absent or decreased megakaryocytes; Group II patients had intermittent periods of chemotherapy-induced thrombocytopenia; and Group III patients had normal or increased megakaryocytes. Controls consisted of 77 healthy adults.

RESULTS

Patients in Group I had markedly increased TPO levels compared to normal controls. Their levels were significantly different (p = 0.03) from those of patients in Group III. The latter had normal or only mildly increased TPO levels except for one patient with myelodysplastic syndrome. Patients in Group II had markedly elevated TPO levels. After their bone marrow and platelet counts recovered from chemotherapy, their TPO levels decreased. In all three groups, a transient increase in platelet count (e.g., after platelet transfusion or anti-D immune globulin therapy) was associated with a moderate decrease in TPO.

CONCLUSIONS

From this study, three conclusions can be made: 1) TPO levels are inversely related to megakaryocyte frequency; 2) platelet counts have a modest influence on TPO level; and 3) TPO levels may have clinical utility in diagnosis and management and further our understanding of the pathobiology of the disorders that cause thrombocytopenia.

Pathogenetic Aspects of Myelodysplastic Syndromes

The myelodysplastic syndromes (MDS) are acquired clonal disorders of the bone marrow. They were clearly defined in morphological terms by the French-American-British (FAB) group in 1982, as five conditions each with their own diagnostic criteria, but with the shared characteristics of ineffective blood cell production in one or more cell line, morphological dysplasia and a variable propensity to evolve into acute myeloid leukaemia (AML). In clinical practice patients typically present in old age with macrocytic anaemia, cytopenias, monocytosis and accumulation of marrow blast cells leading in time to fatal bone marrow failure or AML. To date treatment is unable to alter the natural history of MDS except in those few individuals who are able to undergo allogeneic progenitor cell transplantation.

Hematopoietic and lymphatic malignancies in vehicle mechanics

Although it is generally acknowledged that benzene causes leukemia, especially acute myeloid leukemia, considerable divergences persist in the assessment of the leukemia risk due to occupational low-level benzene exposure. Specifically, the risk for vehicle mechanics is considered by some authors as being nondetectable with epidemiologic methods, whereas others calculated that the incidence rate of leukemia (all types) in vehicle mechanics is increased more than 60 times. The purpose of this review is to examine the publications on this topic in light of criteria for causal inference and to discuss the possible role of bias, confounding factors, and chance. The results of this analysis reveal that there are surprisingly few epidemiologic observations supporting an increased incidence of leukemia in vehicle mechanics. Apparently, publications suggesting a leukemogenic effect of low-level benzene exposure in garage mechanics are more often quoted than their negative counterparts, although they are not better designed.

Diagnostic and prognostic significance of cytogenetics in adult primary myelodysplastic syndromes

Cytogenetic analysis has proven to be a mandatory part of the diagnosis of myelodysplastic syndromes (MDS) as well as a major indicator for predicting clinical course and outcome. This review concentrates on the cytogenetic classifications, the incidence and types of chromosome defects and the prognostic significance of the karyotype in adult primary MDS. Two cytogenetic classifications are currently used: one is based on the karyotype complexity (normal, single, double or complex defects), the other on clonal status (all metaphases normal, abnormal or admixture of normal and abnormal clones). Chromosome abnormalities are of both numerical and structural types. Aside from the 5q-syndrome, no specific clinico-cytogenetic entity has been reported. However, several distinct clinical and cellular features have been identified that correlate with the presence of specific chromosome defects such as inv(3)/t(3;3), +6, t(5;12), del(17p) and del(20q). The presence of complex defects is associated with reduced survival and a high risk of leukemic transformation. Among single defects, specific abnormalities may define distinct prognostic groups. Patients with del(5q) as a sole chromosome defect and a refractory anemia without excess of blasts have a favourable prognosis. For patients with trisomy 8 or monosomy 7 there may be distinct types of clinical evolution. Most patients with the 3q21q26 syndrome have a short survival. The presence of two chromosome defects may constitute an independent cytogenetic entity probably associated with relative poor prognosis. Karyotypic evolution generally represents a poor risk factor. The combination of cytogenetics with clinical and hematological features has proven to provide for a better prediction of patients' survival, leukemic transformation and response to treatment. Several scoring systems have been developed. They have to be improved by the study of new patients according to strict clinical and cytogenetic criteria and by the addition of newly recognized prognostic indicators such as histopathological features and molecular genetic mutations.