The presence of clonal cell subpopulations in peripheral blood and bone marrow of patients with refractory cytopenia with multilineage dysplasia but not in patients with refractory anemia may reflect a multistep pathogenesis of myelodysplasia

3D Telomere Structure Analysis to DetectGenomic Instability and Cytogenetic Evolutionin Myelodysplastic Syndromes

The disease course of myelodysplastic syndromes (MDS) features chromosome instability and clonal evolution, leading to the sequential acquisition of novel cytogenetic aberrations and the accumulation of these abnormalities in the bone marrow. Although clonal cytogenetic abnormalities can be detected by conventional cytogenetics in 50% of patients with MDS, such distinguishing patterns are lacking in the other 50%. Despite the increase in the prognostic value of some biomarkers, none of them is specific and able to discriminate between stable and unstable patients that subsequently progress to acute myeloid leukemia. This pilot study aimed to investigate the potential use of the 3D telomere profiling to detect genomic instability in MDS patients with or without clonal cytogenetic evolution. The comparison between different time points in patients with cytogenetic changes showed that in the CD34+ MDS cells, there was a significant decrease in the total number of telomeric signals, the average intensity of signals and the total intensity of telomeres. By contrast, the number of aggregates increased during cytogenetic evolution (p < 0.001). This pattern was observed only for MDS patients with cytogenetic evolution but was absent in patients without cytogenetic changes. In conclusion, we demonstrated that the 3D nuclear telomere organization was significantly altered during the MDS disease course, and may have contributed to cytogenetic clonal evolution.

Detailed analysis of clonal evolution and cytogenetic evolution patterns in patients with myelodysplastic syndromes (MDS) and related myeloid disorders

Clonal cytogenetic evolution (CE) (i.e., acquisition of new chromosomal aberrations over time) is relevant for the progression of myelodysplastic syndromes (MDS). We performed detailed analysis of CE in 729 patients with MDS and related disorders. Patients with CE showed shorter survival (median OS 18.0 versus 53.9 months; P < 0.01), higher leukemic transformation rate (48.0% versus 21.4%; P < 0.01) and shorter intervals to leukemic transformation (P < 0.01). Two main CE patterns were detected: early versus late CE (median onset 5.3 versus 21.9 months; P < 0.01) with worse survival outcomes for early CE. In the case of CE, del (7q)/−7 (P = 0.020) and del (17p) (P = 0.002) were especially unfavorable. Extending the evolution patterns from Tricot et al. (1985) forming five subgroups, prognosis was best (median OS not reached) in patients with “transient clones/changing clone size”, whereas those with “CE at diagnosis” showed very poor outcomes (P < 0.01 for comparison of all). Detailed sequential cytogenetic analysis during follow-up improves prognostication in MDS patients and acknowledges the dynamic biology of the disease. Evidence, time-point, and patterns of cytogenetic clonal evolution should be included into future prognostic scoring systems for MDS.

Demonstration of the Cell Clonality in Canine Hematopoietic Tumors by X-chromosome Inactivation Pattern Analysis

X-chromosome inactivation pattern (XCIP) analysis has been widely used to assess cell clonality in various types of human neoplasms. In this study, a polymerase chain reaction–based canine XCIP analysis of the androgen receptor ( AR) gene was applied for the assessment of cell clonality in canine hematopoietic tumors. This XCIP analysis is based on the polymorphic CAG repeats in the AR gene and the difference of methylation status between active and inactive X chromosomes. We first examined the polymorphisms of 2 CAG tandem repeats in the AR gene in 52 male and 150 female dogs of various breeds. The 2 polymorphic CAG repeats contained 9 to 12 and 10 to 14 CAGs in the first and second CAG repeats, respectively. Of the 150 female dogs, 74 (49.3%) were heterozygous for the first and/or second polymorphic CAG tandem repeats, indicating the utility of XCIP analysis in these dogs. Canine XCIP analysis was then applied to clinical samples from female dogs with canine high-grade lymphoma, chronic myelogenous leukemia, acute myelogenous leukemia, and benign lymph node hyperplasia. Of 10 lymphoma cell samples, 9 (90%) showed skewed XCIPs, indicating their clonal origins, whereas all the nonneoplastic lymph node samples showed balanced XCIPs. Moreover, bone marrow specimen from a dog with acute myelogenous leukemia and peripheral leukocyte specimens from 2 dogs with chronic myelogenous leukemia showed skewed XCIPs. XCIP analysis was successfully employed to demonstrate the cell clonality of canine hematopoietic tumors in this study and will be applicable to evaluate the clonality in various proliferative disorders in dogs.

X-Chromosome Inactivation Pattern Analysis for the Assessment of Cell Clonality in Cats

X-chromosome inactivation pattern (XCIP) analysis has been widely used to assess cell clonality in various types of neoplasms in humans. In the present study, a polymerase chain reaction–based feline XCIP analysis using the feline androgen receptor gene was developed. To construct the system of the analysis, polymorphism in CAG tandem repeats within the feline androgen receptor gene was explored using somatic DNAs from 50 male and 103 female cats. CAG tandem repeats in exon 1 of the feline androgen receptor gene were found to be polymorphic, containing 15 to 22 CAG repeats. Of the 103 female cats, 70 (68%) were heterozygous for the number of CAG repeats, indicating the possible usefulness of XCIP analysis in cats. Application of the feline XCIP analysis to 3 feline mammary gland adenocarcinoma cell lines revealed distinctly skewed XCIPs in these cell lines, indicating their clonal origins. Twelve (80%) of the 15 primary tissue/cell samples obtained from cats with various neoplastic diseases showed skewed XCIPs. Moreover, bone marrow samples from 3 cats with myelodysplastic syndrome were also found to have skewed XCIPs. The polymerase chain reaction–based XCIP analysis developed in this study can provide information on cell clonality in female cats, potentially facilitating the differential diagnosis of various disorders in cats.

From cryptic chromosomal lesions to pathologically relevant genes: integration of SNP-array with gene expression profiling in myelodysplastic syndrome with normal karyotype

Myelodysplastic syndrome (MDS), a clonal disorder originating from hematopoietic stem cell, is characterized by a progressive character often leading to transformation to acute myeloid leukemia. We used single nucleotide polymorphism arrays (SNP-A) to identify previously cryptic chromosomal abnormalities such as copy number alterations and uniparental disomies (UPD) in cytogenetically normal MDS. In the aberrant regions, we attempted to localize candidate genes with potential relevance to the disease. Using SNP-A, we analyzed peripheral blood granulocytes from 37 MDS patients. The analysis identified 13 cryptic chromosomal defects in 10 patients (27%). Four UPD (affecting chromosomes 3q, 7q, 17q, and 20p), 5 deletions and 4 duplications were detected. Gene expression data measured on CD34+ cells were available for 4 patients with and 6 patients without SNP-A lesions. We performed an integrative analysis of genotyping and gene expression microarrays and found several genes with an altered expression located in the aberrant regions. The expression microarrays suggested BMP2 and TRIB3 located in 20p UPD as potential candidate genes contributing to MDS. We showed that the genome-wide integrative approach is beneficial to the comprehension of molecular backgrounds of diseases with incompletely understood etiopathology.

Diagnostic yield of bone marrow and peripheral blood FISH panel testing in clinically suspected myelodysplastic syndromes and/or acute myeloid leukemia: a prospective analysis of 433 cases

It is unclear how often and in what setting fluorescence in situ hybridization (FISH) panels for myelodysplastic syndrome (MDS)/acute myeloid leukemia (AML) provide additional information over metaphase cytogenetics alone. Furthermore, the usefulness of peripheral blood vs bone marrow FISH has also not been directly compared. We prospectively compared metaphase cytogenetics and FISH for -5/5q-, -7/7q-, +8, and 20q- in 433 cases of suspected MDS/AML. FISH testing was abnormal in 6 (14%) of 43 and 10 (19%) of 54 cases with fewer than 20 normal metaphases or no growth, respectively. FISH was only rarely abnormal in cases with 20 normal metaphases obtained (6/222 [2.7%]). Comparison of peripheral blood and bone marrow results in 48 cases showed abnormal peripheral blood FISH results in 18 (69%) of 26 cases with abnormal bone marrow FISH results and in 5 (23%) of 22 cases with normal bone marrow FISH results. These findings, the largest published comparison of FISH vs metaphase cytogenetics in MDS/AML, provide a rational strategy for FISH testing in peripheral blood and bone marrow.

The lower risk MDS patient at risk of rapid progression

Most patients with myelodysplastic syndrome (MDS) are classified at diagnosis as having a low/INT-I or INT-II/high risk disease, based on the classical International Prognostic Scoring System (IPSS) criteria. The low/INT-I risk patients are usually managed mildly with supportive care, including red blood cell (RBC) transfusions, erythroid stimulating agents (ESAs), other cytokines (G-CSF, platelet stimulating agents), as well as thalidomide and lenalidomide. Some patients receive immunosuppressive therapy, and iron chelation is indicated in iron overloaded patients. Aggressive approach (hypomethylating agents, chemotherapy and stem cell transplantation) is usually not applied in such patients. Occasionally, we observe a "low risk" patient with rapid progression of disease and poor outcome. Can we identify demographic, clinical, laboratory, cellular-biological and/or molecular parameters that can predict "poor prognostic features" (PPF) in "low risk" MDS patients? Clinical and laboratory parameters have been reported to be associated with poor prognosis, in addition to the known "classical" IPSS criteria. These include older age, male gender, poor performance status, co-morbidities, degree of anemia, low absolute neutrophile count (ANC) and platelet counts, RBC transfusion requirements, high serum ferritin, high LDH, bone marrow (BM) fibrosis, increased number of BM CD34+ cells and multi-lineage dysplasia. Certain immunophenotypes (low CD11b, high HLA-Dr, CD34, CD13 and CD45), clonal granulocytes, multiple chromosomal abnormalities, chromosomal instability, short telomeres and high telomerase activity were also reported as PPF. Studies of apoptosis identified Bcl-2 expression and high caspase 3 as PPF, while the reports on survivin expression have been confusing. Recent exciting data suggest that methylation of p15 INK4b and of CTNNA1 (in 5q-), high level of methylation of other genes, absence of the TET2 mutation, down regulation of the lymphoid enhancer binding factor 1 (LEF1), mutation of the polycomb-associated gene ASXL1 and a specific 6-gene signature in gene expression profiling - are all associated with poor prognosis in MDS. Do we have data suggesting a different treatment for "low risk" MDS patients displaying PPF? Two teams, the combined Nordic-Italian and the GFM groups have reported an improved survival with ESAs. The GFM has achieved prolonged survival with iron chelation. Recently, encouraging data with survival advantage in azacitidine-treated patients have been published, including a few INT-I patients. Finally, data suggest that low/INT-I MDS patients who undergo stem cell transplantation (SCT0 do better than INT-II/high risk patients). In summary, some patients, classified as "low risk MDS" carry PPF. An appropriate therapeutic approach is indicated. Future updated classifications and prospective trials may lead to a better outcome.

Myelodysplastic syndromes classification and risk stratification

Myelodysplastic syndromes (MDS) are spectrum of bone marrow failure disorders that share a common pathologic feature: cytologic dysplasia. The classification of MDS reflects the understanding of the disease. It is hoped that in the future classification and risk stratification will be based on underlying pathobiology of different disease subsets and molecular signatures where the pathologic classification represents their phenotype. This article reviews MDS classification and risk stratification highlighting differences between the various systems.

Epidemiology, classification and prognosis of adults and children with myelodysplastic syndromes

Myelodysplastic syndromes (MDS) belong to the most frequent bone marrow diseases with a crude incidence of about 4 in 100,000 per year. The diagnosis of MDS still is mainly based on morphologic findings in blood and marrow. The new WHO classification system takes into account the medullary and peripheral blast count as well as the degree of dysplasia in the different cell lines. To correctly identify MDS types, cytogenetic evaluation is of importance, as the WHO classification introduced the entity MDS with del(5q), which is characterized by special morphologic and hematologic features. The separation of MDS from acute leukemias has been redefined using a cutoff value of 20% peripheral and/or medullary blasts. The International Prognostic Scoring System still is the gold standard in prognostication, but new items like transfusion need will be used more and more and have been incorporated into the WHO adapted Prognostic Scoring System. In childhood, MDS is uncommon, accounting for less than 5% of all hematopoietic neoplasms in patients less than 14 years of age. To accommodate for the characteristics of pediatric MDS, a simple classification scheme based on morphological features and conforming with the WHO suggestions was proposed. The dysplastic prodrome of acute myeloid leukemia in Down syndrome is classified within myeloid leukemia in Down syndrome and excluded from the population-based studies of MDS.

Most pediatric patients with essential thrombocythemia show hypersensitivity to erythropoietin in vitro, with rare JAK2 V617F-positive erythroid colonies

Essential thrombocythemia (ET), a Philadelphia (Ph) chromosome negative chronic myeloproliferative disorder, is usually a disease of middle age and it is extremely rare in pediatric patients. In this report we studied 12 children diagnosed with ET and one child with thrombocytosis and family history of ET. We failed to detect JAK2 V617F mutation either in peripheral blood leukocytes or in separated platelets and granulocytes. Monoclonal hematopoiesis was noted in only one female patient. Erythroid progenitors of most of the patients displayed hypersensitivity to erythropoietin (Epo) in vitro; Epo-independent erythroid colonies (EECs) were detected in seven patients. Among EECs of three patients we observed rare colonies heterozygous or homozygous for the JAK2 V617F mutation. Our data suggest that childhood ET patients could bear minor JAK2 V617F-positive subclones.

World Health Organization classification in combination with cytogenetic markers improves the prognostic stratification of patients with de novo primary myelodysplastic syndromes

This study correlated chromosomal defects with French-American-British (FAB)/World Health Organization (WHO) classification subtypes, proposed a revised International Prognostic Scoring System (IPSS) cytogenetic grouping; and established which classification, when used with the IPSS cytogenetic categories, best predicted clinical outcome in the myelodysplastic syndromes (MDS). A higher prevalence of chromosomal defects and distinct defects were observed in patients with multi-lineage dysplasia and a blast cell percentage >10%. Abnormalities of the long arm of chromosome 3, del(7)(q31q35), trisomy 8, del(11)(q14q23), del(12p) and 20q- could be segregated from their respective IPSS cytogenetic categories and used to develop new cytogenetic subgroups. Clinical parameters, FAB/WHO classification, IPSS score and standard or revised cytogenetic categories were statistically relevant for overall survival (OS) and progression-free intervals (PFI) and were included within five distinct multivariate models compared by the Akaike Information Criterion. To predict OS, the best models included age, WHO classification and standard or revised IPSS cytogenetic categories; to predict PFI, the best model included the same variables and revised cytogenetic categories. In conclusion, (i) the WHO classification was associated with a more homogeneous cytogenetic pattern than the FAB classification, (ii) WHO classification and standard/revised IPSS cytogenetic categories were much more effective than IPSS for predicting MDS clinical outcome, (iii) revised cytogenetic subgroups predicted PFI more effectively than standard categories.

Detection of hematopoietic maturation abnormalities by flow cytometry in myelodysplastic syndromes and its utility for the differential diagnosis with non-clonal disorders

The diagnosis of myelodysplastic syndromes (MDS) is based on peripheral cytopenias, bone marrow (BM) morphology and karyotyping. This may be difficult in cases with few dysplastic elements in BM and a normal karyotype. We examined the utility of flow cytometric analysis for the differential diagnosis between MDS and non-clonal disorders (NCD) presenting peripheral cytopenias. Quantitative assessment of CD45, CD16, CD13, CD11b, CD10 and CD64 in granulocytes and monocytes, and CD71 and glycophorin A in erythroblasts besides CD34+ cell count was performed in BM of 31 consecutive newly diagnosed patients with MDS, 11 patients with NCD and 11 healthy controls (BM donors). In MDS, the median number of phenotypic abnormalities found was 3 (1-8). The WPSS score showed a correlation with the total number of changes per case (r=0.48; p=0.002). Decreased SSC in promyelocytes correlated with the peripheral neutrophil count (r=-0.46; p=0.007). In NCD, the normal variation of antigen expression along granulocytic and erythroblast maturation was always maintained. In the discriminant analysis, SSC of CD34+ cells, together with that of promyelocytes and metamyelocytes were able to correctly classify 87% of the cases as clonal or non-clonal. Our quantitative approach permitted to detect at least one abnormality in antigen expression in every case of MDS. However, the most important parameters for differential diagnosis with NCD were the analysis of the granularity in immature cells, especially of the granulocytic series.

The myelodysplastic syndromes: diagnosis, molecular biology and risk assessment

Myelodysplastic syndromes (MDS) are heterogeneous group of neoplastic clonal stem cell diseases characterized by dysplastic morphological features and clinical bone marrow failure. The FAB (French-American-British) system served as the gold standard for MDS classification for more than two decades. The WHO classification, built on the backbone of FAB classification, is an attempt to further improve the prognostic value of MDS classification as well as establish its clinical utility as a tool to select different treatments. In this article we review the epidemiology, pathogenesis, molecular biology, diagnosis and classification of MDS. We highlight the major differences between the FAB classification and the WHO MDS classification. We discuss in more detail the experience of using the new WHO classification since its publication and review the studies that tried to validate the prognostic value of the new classification or apply it to predict clinical responses to various treatments.

Who is WHO in myelodysplastic syndromes? Clinical implications of the WHO classification

Myelodysplastic syndromes (MDS) are a heterogeneous group of neoplastic clonal stem cell diseases characterized by dysplastic morphologic features with a varying percentage of leukemic blasts and clinical bone marrow failure. The French-American-British (FAB) system served as the gold standard of MDS classification for more than two decades. The World Health Organization (WHO) classification, built on the backbone of the FAB classification, is an attempt to further improve the prognostic value of MDS classification as well as to establish its clinical utility as a tool to select different treatments. In this article we highlight the major differences between the FAB classification and the WHO MDS classification. We discuss in more detail the experience of using the new WHO classification since its publication and review the studies that have tried to validate the prognostic value of the new classification or apply it to predict clinical responses to various treatments.

Classification and scoring systems in myelodysplastic syndromes: a retrospective analysis of 311 patients

The main objective of this study was to evaluate the role of the recent World Health Organization (WHO) classification for assessing prognosis in patients with myelodysplastic syndromes (MDS). To this effect, we analyzed the prognostic impact of the WHO and French-American-British (FAB) morphologic classifications and of four different scoring systems in a series of 311 patients with primary MDS diagnosed between October 1990 and June 2001. Both the FAB and WHO classifications identified groups with different prognoses (p<0.0001), those presenting refractory anemia (RA) and refractory anemia with ringed sideroblasts (RARS) showing the best prognosis. The WHO classification subdivided RA into RA with only red cell dysplasia, and refractory cytopenia with multilineage dysplasia (RCMD), and RARS into RARS plus refractory cytopenia with multilineage dysplasia and ringed sideroblast (RCMD-RS). In our population, we have shown that the two subtypes characterized by dysplasia affecting exclusively the erythroid population (RA and RARS) have a better prognosis, with a median survival of 122.2 and 81.9 months, respectively, than those with multilineage dysplasia (RCMD and RCMD-RS) with a median survival of 32.3 and 43.2 months, respectively. There were no significant differences in median survival comparing RA with RAS (p<0.95), or comparing RCMD with RSCMD (p<0.97). Besides, the four scoring systems discriminated our MDS patients in terms of survival, and an increase in prognostic capacity was achieved on adding the score to the morphological classifications. Risk scoring had a greater prognostic impact than the FAB and WHO classifications. Prognostic scoring systems may be an important tool for risk stratification in hematological practice, and add significance to morphological classification. Combined application of the WHO classification and score system is useful for improving the identification of patients with a poorer prognosis. The WHO classification establishes more homogeneous subcategories than the FAB classification and is also able to identify groups with different prognoses.

Maturation-associated immunophenotypic abnormalities in bone marrow B-lymphocytes in myelodysplastic syndromes

Recent studies concerning the pathophysiology of myelodysplastic syndromes (MDS) have shown evidences for the existence of complex interactions between hematopoietic stem cells and the bone marrow (BM) microenvironment. We analyzed the B-lymphocyte maturation in BM of patients with MDS. For this purpose, 41 newly-diagnosed patients were analyzed. Enumeration and characterization of CD34+ and CD34- B-cell precursors and mature B-lymphocytes was performed using multiparameter flow cytometry. BM from eight transplant donors and six orthopedic surgery patients were used as controls. CD34+/CD45(lo) B-cells were found in 17/22 patients with RA/RARS and in 5/13 with RAEB. In patients with RAEB-t and CMML no CD34+ B-cell precursors could be detected. A positive correlation was found between CD34+ and CD34- B-cell precursors (r=0.52). CD34+ B-cell precursors presented an inverse correlation with BM percentage of blasts and peripheral leukocytes and a positive one with hemoglobin. Asynchronous antigen expression (CD19+/CD79a- cells) was found in 7/11 cases of RA/RARS and 6/18 cases of RAEB in which this phenotype was examined. Abnormal patterns of expression for at least one antigen was found in 91% of RA/RARS cases and in 74% of RAEB. Underexpression of TdT and CD79a were the most frequent abnormalities. Our results present evidences of an abnormal B-cell maturation in MDS. This may be an evidence that B-lymphocytes are derived of the abnormal clone. But it may also be the consequence of influences of abnormalities of BM microenvironment leading to an impaired commitment and maturation of the B-cell line in MDS. Studies performed with purified well-characterized B-cells may further elucidate these abnormalities.