Standardization of flow cytometry in myelodysplastic syndromes: report from the first European LeukemiaNet working conference on flow cytometry in myelodysplastic syndromes

The myelodysplastic syndromes are a group of clonal hematopoietic stem cell diseases characterized by cytopenia(s), dysplasia in one or more cell lineages and increased risk of evolution to acute myeloid leukemia (AML). Recent advances in immunophenotyping of hematopoietic progenitor and maturing cells in dysplastic bone marrow point to a useful role for multiparameter flow cytometry (FCM) in the diagnosis and prognostication of myelodysplastic syndromes. In March 2008, representatives from 18 European institutes participated in a European LeukemiaNet (ELN) workshop held in Amsterdam as a first step towards standardization of FCM in myelodysplastic syndromes. Consensus was reached regarding standard methods for cell sampling, handling and processing. The group also defined minimal combinations of antibodies to analyze aberrant immunophenotypes and thus dysplasia. Examples are altered numbers of CD34⁺ precursors, aberrant expression of markers on myeloblasts, maturing myeloid cells, monocytes or erythroid precursors and the expression of lineage infidelity markers. When applied in practice, aberrant FCM patterns correlate well with morphology, the subclassification of myelodysplastic syndromes, and prognostic scoring systems. However, the group also concluded that despite strong evidence for an impact of FCM in myelodysplastic syndromes, further (prospective) validation of markers and immunophenotypic patterns are required against control patient groups as well as further standardization in multi-center studies. Standardization of FCM in myelodysplastic syndromes may thus contribute to improved diagnosis and prognostication of myelodysplastic syndromes in the future.     

The prognostic impact of karyotypic subgroups in myelodysplastic syndromes is strongly modified by sex

The prognostic impact of karyotypic patterns in a consecutive series of 389 adult myelodysplastic syndromes (MDS) was investigated. Time period did not significantly influence the survival times. In the analyses, the MDS cases were subdivided into the cytogenetic subgroups used in the International Prognostic Scoring System, i.e. favourable [-Y, del(5q) or del(20q) as single aberrations or normal karyotype, n = 241], poor [-7, del(7q), der(1;7) or complex karyotypes, i.e. > or = three abnormalities, n = 89] and intermediate (other aberrations, n = 59). The survival times correlated well with the prognostic subgroups, confirming that the cytogenetic classification was valid. Expressed as hazard ratios (HRs), with the favourable subgroup as the reference, the intermediate and poor subgroup HRs increased to 1.5 (95% confidence interval, 1.1-2.1) and 3.2 (2.4-4.1) respectively. Sex, age, morphological subtype and smoking habits significantly modified this prognostic impact. Shorter survival was detected for men in the favourable and the intermediate subgroups, but not in the poor prognosis subgroup. Using women in the favourable subgroup as the reference and adjusting for age, the HR for men was 1.6 (1.2-2.1) in the favourable subgroup. Adjusting for smoking habits as well decreased the HR to 1.4 (1.1-2.0) and, when also excluding cases with del(5q) as the sole anomaly, no significant difference could be discerned [HR 1.2 (0.9-1.6], suggesting that the better outcome for women in the favourable subgroup was mainly as a result of the '5q-syndrome' and to smoking habits. In the intermediate subgroup, the corresponding HRs were 3.0 (1.5-6.0) when adjusted for age and 2.7 (1.3-5.5) when also adjusted for smoking habits. Different survival times between men and women have never previously been reported for this MDS group. Although it remains to be elucidated whether environmental and/or constitutional factors cause the observed sex-related difference, these observations have obvious clinical ramifications, not least in designing and evaluating therapy protocols.     

High flow cytometric scores identify adverse prognostic subgroups within the revised international prognostic scoring system for myelodysplastic syndromes

The estimation of survival of myelodysplastic syndromes (MDS) and risk of progression into acute myeloid leukaemia is challenging due to the heterogeneous clinical course. The most widely used prognostic scoring system (International Prognostic Scoring System [IPSS]) was recently revised (IPSS‐R). The aim of this study was to investigate the prognostic relevance of flow cytometry (FC) in the context of the IPSS‐R. Bone marrow aspirates were analysed by FC in 159 patients with MDS. A flow score was calculated by applying the flow cytometric scoring system (FCSS). Patients were assigned to IPSS and IPSS‐R risk groups. The FCSS correlated with the World Health Organization classification, IPSS and IPSS‐R risk groups. Mild flow cytometric abnormalities were associated with significantly better overall survival (OS) and lower risk of disease evolution. The presence of aberrant myeloid progenitors was associated with transfusion dependency and disease progression. Most importantly, the FCSS identified prognostic subgroups within the IPSS‐R cytogenetic good risk and low risk group. Flow cytometric analysis in patients with MDS provides additional prognostic information and is complementary to the IPSS‐R. The addition of a flow cytometric score next to the clinical parameters within the IPSS‐R is a further refinement of prognostication of patients with MDS.     

Lenalidomide is active in Japanese patients with symptomatic anemia in low- or intermediate-1 risk myelodysplastic syndromes with a deletion 5q abnormality

Lenalidomide is an immunomodulatory agent recently reported to be effective in the treatment of transfusion-dependent anemia due to low- or intermediate-1 risk myelodysplastic syndromes (MDS) associated with a deletion 5q (del 5q) cytogenetic abnormality. We conducted a multicenter, single-arm clinical trial to evaluate the safety and efficacy of lenalidomide in Japanese patients with anemia in low- or intermediate-1 risk MDS associated with the del 5q cytogenetic abnormality. Eleven patients (5 with transfusion-dependent anemia; 6 with transfusion-independent symptomatic anemia) received once daily oral administrations of 10 mg of lenalidomide for 21 consecutive days in a 28-day treatment cycle. The efficacy was assessed by the IWG criteria. At an interim analysis after ≥24 weeks of therapy, hemoglobin increase was noted in all 11 patients, with a median increase of 6.0 g/dL (range, 0.9–10.9) from the baseline. All transfusion-dependent patients achieved transfusion independence. Histopathologic and cytogenetic improvement was also noted. Neutropenia and thrombocytopenia were the most common adverse events related to lenalidomide. The adverse events were manageable, and no patients experienced serious adverse events or adverse events requiring treatment discontinuation. The results indicate that lenalidomide can be a useful agent for treating Japanese patients with anemia associated with low- or intermediate-1 risk MDS with the del 5q cytogenetic abnormality.     

Diagnostic utility of flow cytometry in low-grade myelodysplastic syndromes: a prospective validation study

Background

The diagnosis of myelodysplastic syndromes is not always straightforward when patients lack specific diagnostic markers, such as blast excess, karyotype abnormality, and ringed sideroblasts.

Design and Methods

We designed a flow cytometry protocol applicable in many laboratories and verified its diagnostic utility in patients without those diagnostic markers. The cardinal parameters, analyzable from one cell aliquot, were myeloblasts (%), B-cell progenitors (%), myeloblast CD45 expression, and channel number of side scatter where the maximum number of granulocytes occurs. The adjunctive parameters were CD11b, CD15, and CD56 expression (%) on myeloblasts. Marrow samples from 106 control patients with cytopenia and 134 low-grade myelodysplastic syndromes patients, including 81 lacking both ringed sideroblasts and cytogenetic aberrations, were prospectively analyzed in Japan and Italy.

Results

Data outside the predetermined reference range in 2 or more parameters (multiple abnormalities) were common in myelodysplastic syndromes patients. In those lacking ringed sideroblasts and cytogenetic aberrations, multiple abnormalities were observed in 8/26 Japanese (30.8%) and 37/55 Italians (67.3%) when the cardinal parameters alone were considered, and in 17/26 Japanese (65.4%) and 42/47 Italians (89.4%) when all parameters were taken into account. Multiple abnormalities were rare in controls. When data from all parameters were used, the diagnostic sensitivities were 65% and 89%, specificities were 98% and 90%, and likelihood ratios were 28.1 and 8.5 for the Japanese and Italian cohorts, respectively.

Conclusions

This protocol can be used in the diagnostic work-up of low-grade myelodysplastic syndromes patients who lack specific diagnostic markers, although further improvement in diagnostic power is desirable.     

Expression and prognostic significance of heat-shock proteins in myelodysplastic syndromes

Using flow cytometry, we investigated the clinical and hematologic relevance of expression of heat-shock proteins (HSP) HSP27, HSP60, HSP70, HSP90 and HSP110 in bone marrow of 142 patients with newly diagnosed myelodysplastic syndromes, together with that of the membrane differentiation antigen CD34 and the drug-resistance related protein, P170 (Pgp).     

Evaluation of the prognostic relevance of L-selectin and ICAM1 expression in myelodysplastic syndromes

Objectives:  An aberrant pattern of expression of l -selectin and intercellular adhesion molecule 1 (ICAM1) may characterise CD34⁺ blast cells in myelodysplastic syndromes (MDS) and secondary acute myeloid leukaemia (sAML).
Methods:  In a three-colour flow cytometric assay, we evaluated the expression of l -selectin and ICAM1 on CD34⁺ blast cells from the bone marrow (BM) of 66 MDS patients; for the purpose of comparison CD34⁺ blast cells of 18 sAML and CD34⁺ stem cells of 17 normal donors were also analysed.
Results:  The ratio of l -selectin/ICAM1 expression was identified as a parameter correlated with the percentage of BM blast infiltration and the time to leukaemic progression among MDS patients. In fact, the values of l -selectin/ICAM1 ratio were inversely correlated with the BM blast infiltration ( r  = –0.34, P  = 0.004). Furthermore, MDS patients with a baseline ratio <1 had a higher leukaemic progression rate (41% vs. 19%, P  = 0.008); the actuarial risk of disease progression for this subgroup of MDS patients was also higher (64% vs. 11% at 2 yr, P  = 0.002). Furthermore, in two patients a decrease of the ratio was observed when overt leukaemic transformation occurred; conversely, restoration of a normal ratio was observed in two patients after a chemotherapy-induced remission.
Conclusion:  (i) l -selectin is defective in the stem cell compartment of MDS and sAML, whereas ICAM1 is overexpressed; (ii) the ratio of their expression has a prognostic role; and (iii) a ratio <1 significantly predicts progression to overt leukaemia in MDS patients.     

Mechanisms and prognostic value of cell kinetics in the myelodysplastic syndromes

Cell kinetics were studied by quantitative autoradiography in 29 patients with myelodysplastic syndromes (MDS) and in four with smouldering leukaemia (SML) in a prospective 6–year study. Cellular turnover in all FAB groups was characterized by reduced labelling index and prolonged DNA synthesis time indicating reduced proliferative activity. Two more parameters were derived from the measurements. (1) The relative cell production rate, which is increased in proerythroblasts and myeloblasts in most cases. This could be attributed to an increased number of divisions in early recognizable precursors in the absence of maturation, and (or) an increased influx from the progenitor compartments. (2) The maturation index of a cell lineage was determined by the ratio of relative cell production rate increase from the first to the last proliferative compartment over the corresponding normal value. It showed a high degree of abnormality in all FAB subgroups, indicating premature cell death in the bone marrow. None of the kinetic parameters proved to be of value in predicting the evolution of leukaemia. In contrast, an excellent correlation was found between the myeloid maturation index and survival ( P <0.0001). No correlation, however, was found between survival and the erythroid maturation index, which was relatively normal in the worst prognostic group. These findings indicate that although in vitro cell kinetic studies can not predict the evolution of overt leukaemia, the myeloid maturation index is a useful predictor of survival in patients with MDS and SMI.     

Evaluation of apoptosis as a prognostic factor in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) are a group of disorders characterized by peripheral pancytopenia despite normo- or hypercellular bone marrow. This is thought to be as a result of the apoptosis of haematopoietic bone marrow cells resulting in ineffective haematopoiesis. To clarify the relationship between prognosis and apoptosis and/or cell proliferation in the bone marrow, we studied 51 cases with MDS. Bone marrow biopsies were stained immunohistochemically for MIB-1 (marker for proliferating cells) and CD34 (marker for stem cells). Apoptosis was visualized by detection of DNA fragmentation using TdT incorporation of nucleotides on 3' ends of DNA (TUNEL technique) and expressed as the apoptotic rate. MDS patients included 32 with refractory anaemia (RA), one RA with ringed sideroblasts (RARS) patient, seven RA with excess of blasts (RAEB) patients, eight patients with RAEB in transformation (RAEB-t) and three patients with chronic myelomonocytic leukaemia (CMMoL). In addition, we also studied six cases with acute myeloid leukaemia (AML) arising from MDS (AML-MDS) and ten control subjects. Fatal pancytopenia was the cause of death in 19 out of 51 patients. The apoptotic rate was higher in MDS patients (5.5%) than in control subjects (0.6%) and AML-MDS patients (0.4%). The percentage of MIB-1 positive cells was higher in MDS and AML-MDS than in control. The percentage of CD34-positive cells was higher in AML-MDS, RAEB, RAEB-t and CMMoL patients than control subjects and RA patients. Our findings indicate the activation of both the proliferative and apoptotic rates in MDS. Poor prognosis correlated significantly with higher apoptotic rates, but not with percentages of MIB-1 and CD34-positive cells. Our results suggest that apoptosis might be a useful prognostic factor and inhibition of apoptotic mechanisms may induce leukaemic transformation in MDS.     

Flow cytometry for diagnosis and assessment of prognosis in patients with myelodysplastic syndromes

The Myelodysplastic Syndrome (MDS) comprises a spectrum of hematopoietic stem cell disorders. Identification of additional parameters that might distinguish different risk groups or entities would be useful. Flow cytometric studies have begun to characterize individual or composite immunophenotypic abnormalities as well as light scatter properties that may be helpful for diagnosis and of prognostic value for the natural course of the disease and for outcome after therapy. Here we review the current state of the art of the use of flow cytometry in patients with MDS.     

Platelet mass has prognostic value in patients with myelodysplastic syndromes

Platelet mass (mean platelet volume x platelet count) can be derived from data obtained from the routine full blood count and separates patients with myelodysplastic syndromes (MDS) at diagnosis into three distinct prognostic groups: low platelet mass group - median survival 5 months and 5-year survival 0%; intermediate platelet mass group - median survival 30 months and 5-year survival 34%; high platelet mass group median survival - not reached at 82 months follow-up with a 5-year survival of 82%. These data provide a simple rapid prognostic index at the time of diagnosis in MDS.     

Prevalence and prognostic significance of allelic imbalance by single-nucleotide polymorphism analysis in low-risk myelodysplastic syndromes

Low-risk myelodysplastic syndrome (MDS) with normal cytogenetics accounts for approximately 50% of MDS patients. There are no pathognomonic markers in these cases and the diagnosis rests on cytomorphologic abnormalities in bone marrow and/or peripheral blood. Affymetrix high-resolution single-nucleotide polymorphism (SNP) genotyping microarrays allow detection of cytogenetically cryptic genomic aberrations. We have studied 119 low-risk MDS patients (refractory anemia [RA] = 22; refractory cytopenia with multilineage dysplasia [RCMD] = 51; refractory anemia with ringed sideroblasts [RARS] = 12; refractory cytopenia with multilineage dysplasia with ringed sideroblasts [RCMD-RS] = 12; 5q- syndrome = 16; refractory anemia with excess blasts [RAEB] = 6) using SNP microarrays to seek chromosomal markers undetected by conventional cytogenetics. Loss of heterozygosity (LOH) detected by 50K arrays was verified using 250K and 500K arrays. We demonstrate the presence of uniparental disomy (UPD) in 46%, deletions in 10%, and amplifications in 8% of cases. Copy number (CN) changes were acquired, whereas UPDs were also detected in constitutional DNA. UPD on 4q was identified in 25% of RARS, 12% of RCMD with normal cytogenetics, 17% of RAEB, and 6% of 5q- syndrome cases. Univariate analysis showed deletions (P = .04) and International Prognostic Scoring System (IPSS; P < .001) scores correlated with overall survival; however, on multivariate analysis only IPSS scores retained prognostic significance (P < .001). We show, for the first time, that SNP microarray analysis in low-risk MDS patients reveals hitherto unrecognized UPD and CN changes that may allow stratification of these patients for early therapeutic interventions.     

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.     

The prognostic value of circulating myeloblasts in patients with myelodysplastic syndromes

The prognostic value of peripheral blasts (PB) is not well-studied in patients with myelodysplastic syndromes (MDS). We evaluated the impact of PB on overall survival (OS) and transformation to acute myeloid leukemia (AML) in a large cohort. The MDS database at the Moffitt Cancer Center was retrospectively reviewed to identify patients with ≥?1% PB (PB-MDS) and those without PB (BM-MDS). We also assessed the correlation between PB and gene mutations. One thousand seven hundred fifty-eight patients were identified, among whom 13% had PB near the time of diagnosis. PB-MDS patients were more likely to be younger with trilineage cytopenia, complex karyotype, higher-risk disease, transfusion dependence, and therapy-related MDS. The rate of AML transformation was 49 vs. 26% (p?<?0.005) and median OS was 16.5 vs. 45.8 months (p?<?0.005) in the PB-MDS and BM-MDS groups, respectively. In Cox regression analysis, the presence of PB was an independent prognostic covariate for OS, HR 1.57 (95% CI 1.2–2). Among 51 patients with an available gene panel, the rate of ≥?1 gene mutation in the PB-MDS group (n?=?4) was 100% compared to 81% in the BM-MDS group (n?=?47). The presence of PB in MDS is an adverse independent prognostic variable that refines prognostic discrimination.     

Phase 2 study of lenalidomide in transfusion-dependent, low-risk, and intermediate-1 risk myelodysplastic syndromes with karyotypes other than deletion 5q

Lenalidomide is approved for red blood cell (RBC) transfusion-dependent anemia due to low or intermediate-1 (int-1) risk myelodysplastic syndromes (MDSs) associated with a chromosome 5q deletion with or without additional cytogenetic abnormalities. We report results of a multicenter, phase 2 trial evaluating lenalidomide therapy for transfusion-dependent patients with low- or int-1-risk MDS without deletion 5q. Eligible patients had 50,000/mm(3) or more platelets and required 2 U or more RBCs within the previous 8 weeks; 214 patients received 10 mg oral lenalidomide daily or 10 mg on days 1 to 21 of a 28-day cycle. The most common grade 3/4 adverse events were neutropenia (30%) and thrombocytopenia (25%). Using an intention-to-treat analysis, 56 (26%) patients achieved transfusion independence (TI) after a median of 4.8 weeks of treatment with a median duration of TI of 41.0 weeks. In patients who achieved TI, the median rise in hemoglobin was 32 g/L (3.2 g/dL; range, 10-98 g/L [1.0-9.8 g/dL]) from baseline. A 50% or greater reduction in transfusion requirement occurred in 37 additional patients, yielding a 43% overall rate of hematologic improvement (TI response + ||>or= 50% reduction in transfusion requirement). Lenalidomide has clinically meaningful activity in transfusion-dependent patients with low- or int-1-risk MDS who lack the deletion 5q karyotypic abnormality.     

Identification and characterization of liver nonparenchymal cells by flow cytometry

Our objective was to correlate biochemical or functional properties that could be measured by fluorescence to individual nonparenchymal cell types by the simultaneous detection of forward angle light scatter and fluorescence. Cells were released from liver following selective digestion of hepatocytes by Pronase perfusion. To fractionate the cells according to size, isolates were subjected to unit gravity sedimentation on a 1 to 5% sucrose gradient. Flow cytometry was used to analyze the resulting fractions as well as the original unfractionated cells. This reaffirmed that forward angle light scatter is linearly related to the sedimentation velocity (size) of the cells and that it can be used to assess cell sizes in an unfractionated population. Endocytosis of fluorescently tagged particulates was studied by injecting either fluorescein isothiocyanate-tagged colloidal albumin or Coumarin-tagged latex beads (0.57 micron diameter) prior to Pronase perfusion. Beads were found only in the largest cells (Kupffer cells). Since endothelial cells could endocytose only colloidal albumin, they were readily differentiated from nonendocytosing, nonsinusoidal cells ("lymphocytes"). Staining cell protein with fluorescein isothiocyanate made possible the determination of relative protein content per cell ("lymphocyte": endothelial:Kupffer cell was 0.57:1.0:2.0). To determine relative esterase activities, mixed cell isolates were incubated in fluorescein diacetate ("lymphocyte":endothelial:Kupffer cells was 0.13:1.0:2.4). Uptake of rhodamine 123 was used to assess mitochondrial function ("lymphocyte":endothelial:Kupffer cells was 0.45:1.0:14.6). Mitochondrial volume per cell is known to be 1:2 for endothelial:Kupffer cells. Therefore, the large difference in rhodamine uptake is not related to volume.     

Hypoalbuminemia is an independent prognostic factor for overall survival in myelodysplastic syndromes

We hypothesized that hypoalbuminemia is an independent prognostic factor in patients with myelodysplastic syndromes (MDS). We analyzed records of 767 patients treated at Moffitt Cancer Center between January 2001 and December 2009 to evaluate the relationship between serum albumin (SA) at the time of presentation and overall survival (OS). Patients (median age of 69 years) were stratified into three groups based on SA concentration (≤3.5, 3.6–4.0, and >4.0 g/dL). Two‐thirds of the patients had low or intermediate‐1 International Prognostic Scoring System (IPSS)‐based risk for MDS. Median OS by SA concentration of ≤3.5, 3.6–4.0, and >4.0 g/dL was 11, 23, and 34 months, respectively (P < 0.005), whereas rate of acute myeloid leukemia progression was highest in patients with low SA (≤3.5 g/dL). The SA level offered prognostic discrimination for outcomes within the lower and higher IPSS risk groups, as well as with the MD Anderson risk model. In multivariable analysis, SA was a significant independent co‐variate for OS after adjustment for IPSS, age, serum ferritin, and transfusion dependence (hazard ratio = 0.8; 95% CI 0.6–0.9; P = 0.004). Our findings indicate that hypoalbuminemia is an independent prognostic biomarker that may serve as a surrogate representative of disease biology or comorbidities in patients with MDS. Am. J. Hematol., 2012. © 2012 Wiley Periodicals, Inc.