Dysplasia and PNH-type cells in bone marrow aspirates of myelodysplastic syndromes.

BACKGROUND: Flow cytometry is increasingly applied in cytopenic patients suspected for myelodysplastic syndromes (MDS). Analysis includes evaluation of antigen expression patterns in granulocytes of which, for example, partial lack of CD16 may indicate dysplasia, but presence of paroxysmal nocturnal hemoglobinuria (PNH)-type cells should be considered. However, diagnostic bone marrow (BM) samples hamper PNH analysis because immature stages in the granulo-/monocytic compartment lack expression of certain glycophosphatidyl-inositol-anchored proteins. In this prospective study, we evaluated the presence of PNH-type cells in BM next to aberrancies from routine MDS immunophenotyping. METHODS: We combined antibodies defining maturation trajectories with FLAER. Validation of the designed method against routine PNH analysis and parallel analysis of BM and blood samples revealed similar results (granulocytes: Wilcoxon p = 0.25 and p = 0.82, respectively). We analyzed BM samples from 134 MDS, 17 chronic myelomonocytic leukemia, 15 aplastic anemia (AA), 1 PNH, 51 non-clonal cytopenic controls, and 12 normal controls. RESULTS: Most AA/PNH-BM samples showed clear PNH clones: median 1.1% (0%-35%); CD16 loss on mature neutrophils paralleled PNH-clone sizes. In MDS-BM, only 3.7% of cases showed ≥0.1% PNH-type cells, whereas partial CD16 loss was more frequent and abundant. CONCLUSIONS: Our findings confirm that dysplastic features in MDS-BM may point to presence of PNH-type cells, though only few cases displayed FLAER-negative cells. We showed that identification of these cells in the granulocyte compartment of BM specimen is feasible, but-according to international guidelines-results need to be confirmed in peripheral blood.

Flow cytometric analysis of myelodysplasia: Pre-analytical and technical issues-Recommendations from the European LeukemiaNet.

BACKGROUND: Flow cytometry (FCM) aids the diagnosis and prognostic stratification of patients with suspected or confirmed myelodysplastic syndrome (MDS). Over the past few years, significant progress has been made in the FCM field concerning technical issues (including software and hardware) and pre-analytical procedures. METHODS: Recommendations are made based on the data and expert discussions generated from 13 yearly meetings of the European LeukemiaNet international MDS Flow working group. RESULTS: We report here on the experiences and recommendations concerning (1) the optimal methods of sample processing and handling, (2) antibody panels and fluorochromes, and (3) current hardware technologies. CONCLUSIONS: These recommendations will support and facilitate the appropriate application of FCM assays in the diagnostic workup of MDS patients. Further standardization and harmonization will be required to integrate FCM in MDS diagnostic evaluations in daily practice.

Clinical application of flow cytometry in patients with unexplained cytopenia and suspected myelodysplastic syndrome: A report of the European LeukemiaNet International MDS-Flow Cytometry Working Group.

This article discusses the rationale for inclusion of flow cytometry (FCM) in the diagnostic investigation and evaluation of cytopenias of uncertain origin and suspected myelodysplastic syndromes (MDS) by the European LeukemiaNet international MDS Flow Working Group (ELN iMDS Flow WG). The WHO 2016 classification recognizes that FCM contributes to the diagnosis of MDS and may be useful for prognostication, prediction, and evaluation of response to therapy and follow-up of MDS patients.

Multiparameter flow cytometry in the evaluation of myelodysplasia: Analytical issues: Recommendations from the European LeukemiaNet/International Myelodysplastic Syndrome Flow Cytometry Working Group.

Multiparameter flow cytometry (MFC) is one of the essential ancillary methods in bone marrow (BM) investigation of patients with cytopenia and suspected myelodysplastic syndrome (MDS). MFC can also be applied in the follow-up of MDS patients undergoing treatment. This document summarizes recommendations from the International/European Leukemia Net Working Group for Flow Cytometry in Myelodysplastic Syndromes (ELN iMDS Flow) on the analytical issues in MFC for the diagnostic work-up of MDS. Recommendations for the analysis of several BM cell subsets such as myeloid precursors, maturing granulocytic and monocytic components and erythropoiesis are given. A core set of 17 markers identified as independently related to a cytomorphologic diagnosis of myelodysplasia is suggested as mandatory for MFC evaluation of BM in a patient with cytopenia. A myeloid precursor cell (CD34+ CD19- ) count >3% should be considered immunophenotypically indicative of myelodysplasia. However, MFC results should always be evaluated as part of an integrated hematopathology work-up. Looking forward, several machine-learning-based analytical tools of interest should be applied in parallel to conventional analytical methods to investigate their usefulness in integrated diagnostics, risk stratification, and potentially even in the evaluation of response to therapy, based on MFC data. In addition, compiling large uniform datasets is desirable, as most of the machine-learning-based methods tend to perform better with larger numbers of investigated samples, especially in such a heterogeneous disease as MDS.

Distinct bone marrow immunophenotypic features define the splicing factor 3B subunit 1 (SF3B1)-mutant myelodysplastic syndromes subtype.

Splicing factor 3B subunit 1 (SF3B1) mutations define a distinct myelodysplastic syndromes (MDS) patient group with a relatively favourable disease course and high response rates to luspatercept. Few data are available on bone marrow phenotype beyond ring sideroblasts in this subgroup of patients with MDS. In the present study, we identified immunophenotypic erythroid, myelomonocyte and progenitor features associated with SF3B1 mutations. In addition, we illustrate that SF3B1-mutation type is associated with distinct immunophenotypic features, and show the impact of co-occurrence of a SF3B1 mutation and a deletion of chromosome 5q on bone marrow immunophenotype. These genotype-phenotype associations and phenotypic subtypes within SF3B1-MDS provide leads that may further refine prognostication and therapeutic strategies for this particular MDS subgroup.

Monitoring treatment with 5-Azacitidine by flow cytometry predicts duration of hematological response in patients with myelodysplastic syndrome.

5-Azacitidine (AZA) therapy is used in high-risk myelodysplastic syndrome (MDS) patients who often show abnormalities in their immunophenotype. We explored the potential impact of AZA on these immunophenotypic abnormalities in serial bone marrow studies performed in 81 patients from five centers. We compared the immunophenotypic features before and after therapy with AZA, established definitions consistent with flow cytometry immunophenotyping (FCI) improvement, and explored its clinical significance. After a median of 6 cycles of AZA, 41% of patients showed a FCI improvement and this finding associated with best possible clinical response (P < 0.001). FCI improvement also correlated with hematological improvement (HI) (53/78 patients; 68%), independently of their eligibility for stem cell transplantation. Among patients who achieved a HI after 6 cycles of AZA, the probability of maintaining this response at 12 cycles of AZA was twice as large (67%) for those patients who also achieved a FCI improvement after 6 cycles of AZA as compared to patients who did not (33%, P < 0.01). These findings support that monitoring of the immunophenotypic abnormalities during therapy with AZA may assist in redefining the quality of response in patients with MDS.

Genomic array as compared to karyotyping in myelodysplastic syndromes in a prospective clinical trial.

Karyotyping is considered as the gold standard in the genetic subclassification of myelodysplastic syndrome (MDS). Oligo/SNP-based genomic array profiling is a high-resolution tool that also enables genome wide analysis. We compared karyotyping with oligo/SNP-based array profiling in 104 MDS patients from the HOVON-89 study. Oligo/SNP-array identified all cytogenetically defined genomic lesions, except for subclones in two cases and balanced translocations in three cases. Conversely, oligo/SNP-based genomic array profiling had a higher success rate, showing 55 abnormal cases, while an abnormal karyotype was found in only 35 patients. In nine patients whose karyotyping was unsuccessful because of insufficient metaphases or failure, oligo/SNP-based array analysis was successful. Based on cytogenetic visible abnormalities as identified by oligo/SNP-based genomic array prognostic scores based on IPSS/-R were assigned. These prognostic scores were identical to the IPSS/-R scores as obtained with karyotyping in 95%-96% of the patients. In addition to the detection of cytogenetically defined lesions, oligo/SNP-based genomic profiling identified focal copy number abnormalities or regions of copy neutral loss of heterozygosity that were out of the scope of karyotyping and fluorescence in situ hybridization. Of interest, in 26 patients we demonstrated such cytogenetic invisible abnormalities. These abnormalities often involved regions that are recurrently affected in hematological malignancies, and may therefore be of clinical relevance. Our findings indicate that oligo/SNP-based genomic array can be used to identify the vast majority of recurrent cytogenetic abnormalities in MDS. Furthermore, oligo/SNP-based array profiling yields additional genetic abnormalities that may be of clinical importance.

Implementation of erythroid lineage analysis by flow cytometry in diagnostic models for myelodysplastic syndromes.

Flow cytometric analysis is a recommended tool in the diagnosis of myelodysplastic syndromes. Current flow cytometric approaches evaluate the (im)mature myelo-/monocytic lineage with a median sensitivity and specificity of ~71% and ~93%, respectively. We hypothesized that the addition of erythroid lineage analysis could increase the sensitivity of flow cytometry. Hereto, we validated the analysis of erythroid lineage parameters recommended by the International/European LeukemiaNet Working Group for Flow Cytometry in Myelodysplastic Syndromes, and incorporated this evaluation in currently applied flow cytometric models. One hundred and sixty-seven bone marrow aspirates were analyzed; 106 patients with myelodysplastic syndromes, and 61 cytopenic controls. There was a strong correlation between presence of erythroid aberrancies assessed by flow cytometry and the diagnosis of myelodysplastic syndromes when validating the previously described erythroid evaluation. Furthermore, addition of erythroid aberrancies to two different flow cytometric models led to an increased sensitivity in detecting myelodysplastic syndromes: from 74% to 86% for the addition to the diagnostic score designed by Ogata and colleagues, and from 69% to 80% for the addition to the integrated flow cytometric score for myelodysplastic syndromes, designed by our group. In both models the specificity was unaffected. The high sensitivity and specificity of flow cytometry in the detection of myelodysplastic syndromes illustrates the important value of flow cytometry in a standardized diagnostic approach. The trial is registered at www.trialregister.nl as NTR1825; EudraCT n.: 2008-002195-10.

Multiparameter flow cytometry is instrumental to distinguish myelodysplastic syndromes from non-neoplastic cytopenias.

Mandatory for the diagnosis of myelodysplastic syndromes (MDS) is the presence of dysplasia in >10% of cells within one or more cell lineages or presence of >15% ring sideroblasts or presence of MDS-associated cytogenetic (CG) abnormalities. Discrimination between neo-plastic and non-neoplastic causes of cytopenias can be challenging when dysplastic features by cytomorphology (CM) are minimal and CG abnormalities are absent or non-discriminating from other myeloid neoplastic disorders. This study evaluated a standard diagnostic approach in 379 patients with unexplained cytopenias and highlights the additional value of flow cytometry (FC) in patients with indeterminate CM and CG. CM reached no clear-cut diagnosis in 44% of the patients. Here, CG was able to identify two additional patients with MDS; other CG results did not reveal abnormalities or were not contributory. Based on the FC results, patients without a diagnosis by CM and CG were categorized 'no MDS-related features' (65%), 'limited number of MDS-related changes' (24%), and 'consistent with MDS' (11%). Patients were followed over time in an attempt to establish or confirm a diagnosis (median follow-up 391 d, range 20-1764). The specificity (true negative) of MDS-FC analysis calculated after follow-up was 95%. FC can aid as a valuable tool to exclude MDS when CM and additional CG are not conclusive in patients with cytopenia.

Application of flow cytometry for myelodysplastic syndromes: Pitfalls and technical considerations.

The application of flow cytometry (FC) is recommended as part of the diagnostic approach for MDS. The complexity of flow cytometric analysis of bone marrow cells in MDS has been an obstacle for general application. However, in the past years several studies showed practical flow cytometric approaches for the diagnosis and prognosis of MDS. In this report we discuss technical considerations and highlight issues that require special attention when handling and analyzing bone marrow samples of patients with cytopenia and suspicion of MDS. © 2015 Clinical Cytometry Society.

Successful Combination of Sequential Gene Therapy and Rescue Allo-HSCT in Two Children with X-CGD - Importance of Timing.

We report on a series of sequential events leading to long-term survival and cure of pediatric X-linked chronic granulomatous disease (X-CGD) patients after gamma-retroviral gene therapy (GT) and rescue HSCT. Due to therapyrefractory life-threatening infections requiring hematopoietic stem cell transplantation (HSCT) but absence of HLAidentical donors, we treated 2 boys with X-CGD by GT. Following GT both children completely resolved invasive Aspergillus nidulans infections. However, one child developed dual insertional activation of ecotropic viral integration site 1 (EVI1) and signal transducer and activator of transcription 3 (STAT3) genes, leading to myelodysplastic syndrome (MDS) with monosomy 7. Despite resistance to mismatched allo-HSCT with standard myeloablative conditioning, secondary intensified rescue allo-HSCT resulted in 100 % donor chimerism and disappearance of MDS. The other child did not develop MDS despite expansion of a clone with a single insertion in the myelodysplasia syndrome 1 (MDS1) gene and was cured by early standard allo-HSCT. The slowly developing dominance of clones harboring integrations in MDS1-EVI1 may guide clinical intervention strategies, i.e. early rescue allo-HSCT, prior to malignant transformation. GT was essential for both children to survive and to clear therapy-refractory infections, and future GT with safer lentiviral self-inactivated (SIN) vectors may offer a therapeutic alternative for X-CGD patients suffering from life-threatening infections and lacking HLA-identical HSC donors.

Immunophenotyping for diagnosis and prognosis in MDS: ready for general application?

Myelodysplastic syndromes is a heterogeneous group of bone marrow diseases ranging from low risk to high risk subtypes that may rapidly evolve to acute myeloid leukemia. Flow cytometry (FCM) is added as a recommended tool for diagnostic purposes in MDS. In recent studies FCM has also shown applicable to predict prognosis and treatment response. This review summarizes current data about the diagnostic, prognostic and therapeutic value of FCM in MDS. The high sensitivity of FCM in the detection of dysplasia in myelo-/monocytic and erythroid cell lineages makes it a valuable tool to distinguish possible clonal causes of cytopenia(s) from non-clonal causes, and to detect multi-lineage dysplasia in addition to cytomorphology. The utility of FCM in prediction of treatment response is promising. Therefore, FCM is an essential tool in standard diagnostic strategies in case of suspected MDS, and ready for general application.

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.

Absence of aberrant myeloid progenitors by flow cytometry is associated with favorable response to azacitidine in higher risk myelodysplastic syndromes.

Background: In intermediate-2 and high risk patients with myelodysplastic syndromes (MDS), treatment with azacitidine is associated with hematological responses and prolonged overall survival in patients who respond to therapy. However, only half of the patients that are treated will benefit from this treatment. It is a major challenge to predict which patients are likely to respond to treatment. The aim of this study was to investigate the predictive value of immunophenotyping for response to treatment with azacitidine of Int-2 and high risk MDS patients. Methods: Bone marrow aspirates were analyzed by flow cytometry in 42 patients with Int-2 and high risk MDS, chronic myelomonocytic leukemia or low blast count acute myeloid leukemia before treatment and after every third cycle of azacitidine. A flow score was calculated using the flow cytometric scoring system (FCSS). Results: The presence of myeloid progenitors with an aberrant immunophenotype was significantly associated with lack of response (p=0.02). A low pretreatment FCSS was associated with significantly better overall survival compared with a high pretreatment FCSS (p=0.03). A significant decrease in FCSS was observed in patients with complete response after three cycles azacitidine compared to patients with progressive disease (p=0.006). Conclusions: Absence of aberrant myeloid progenitor cells at baseline and/or a decrease in the FCSS during treatment identified Int-2 and high risk MDS patients who are likely to respond to treatment with azacitidine. © 2014 Clinical Cytometry Society.

Absence of aberrant myeloid progenitors by flow cytometry is associated with favorable response to azacitidine in higher risk myelodysplastic syndromes.

BACKGROUND: In intermediate-2 (Int-2) and high risk patients with myelodysplastic syndromes (MDS), treatment with azacitidine is associated with hematological improvement and prolonged overall survival (OS) in patients who respond to therapy. However, only half of the patients who are treated will benefit from this treatment. It is a major challenge to predict which patients are likely to respond to treatment. The aim of this study was to investigate the predictive value of immunophenotyping for response to treatment with azacitidine of Int-2 and high risk MDS patients. METHODS: Bone marrow aspirates were analyzed by flow cytometry in 42 patients with Int-2 and high risk MDS, chronic myelomonocytic leukemia, or low blast count acute myeloid leukemia before treatment and after every third cycle of azacitidine. A flow score was calculated using the flow cytometric scoring system (FCSS). RESULTS: The presence of myeloid progenitors with an aberrant immunophenotype was significantly associated with lack of response (p = 0.02). A low pretreatment FCSS was associated with significantly better OS compared with a high pretreatment FCSS (p = 0.03). A significant decrease in FCSS was observed in patients with complete response after three cycles azacitidine compared to patients with progressive disease (p = 0.006). CONCLUSIONS: Absence of aberrant myeloid progenitor cells at baseline and/or a decrease in the FCSS during treatment identified Int-2 and high risk MDS patients who are likely to respond to treatment with azacitidine.

Rationale for the clinical application of flow cytometry in patients with myelodysplastic syndromes: position paper of an International Consortium and the European LeukemiaNet Working Group.

An international working group within the European LeukemiaNet gathered, aiming to determine the role of flow cytometry (FC) in myelodysplastic syndromes (MDS). It was agreed that FC has a substantial application in disease characterization, diagnosis and prognosis. FC may also be useful in predicting treatment responses and monitoring novel and standard therapeutic regimens. In this article the rationale is discussed that flow cytometry should be integrated as a part of diagnostic and prognostic scoring systems in MDS.

Azacitidine differentially affects CD4(pos) T-cell polarization in vitro and in vivo in high risk myelodysplastic syndromes.

CD4(pos) T-cell subsets play a role in myelodysplastic syndromes (MDS) pathogenesis and may be affected upon 5-azacitidine (Aza) treatment. Aza enhanced human T(H)1 frequencies in vitro but not in vivo. The proportion of functional FoxP3(pos) regulatory T cells (Treg) was enhanced by Aza in vitro (p < 0.0002), and a modest, temporary increase was observed in vivo (p = 0.08). The overall number of T(H)17 was reduced both in vitro (p < 0.03) and in vivo (p < 0.006), indicating that Aza directly affects CD4(pos) polarization during activation in vitro. Upon in vivo treatment in high risk MDS patients, particularly the T(H)17-Treg axis is affected.

Multicenter validation of a reproducible flow cytometric score for the diagnosis of low-grade myelodysplastic syndromes: results of a European LeukemiaNET study.

BACKGROUND: The current World Health Organization classification of myelodysplastic syndromes is based morphological evaluation of bone marrow dysplasia. In clinical practice, the reproducibility of the recognition of dysplasia is usually poor especially in cases that lack specific markers such as ring sideroblasts and clonal cytogenetic abnormalities. DESIGN AND METHODS: We aimed to develop and validate a flow cytometric score for the diagnosis of myelodysplastic syndrome. Four reproducible parameters were analyzed: CD34(+) myeloblast-related and B-progenitor-related cluster size (defined by CD45 expression and side scatter characteristics CD34(+) marrow cells), myeloblast CD45 expression and granulocyte side scatter value. The study comprised a "learning cohort" (n=538) to define the score and a "validation cohort" (n=259) to confirm its diagnostic value. RESULTS: With respect to non-clonal cytopenias, patients with myelodysplastic syndrome had increased myeloblast-related cluster size, decreased B-progenitor-related cluster size, aberrant CD45 expression and reduced granulocyte side scatter (P<0.001). To define the flow cytometric score, these four parameters were combined in a regression model and the weight for each variable was estimated based on coefficients from that model. In the learning cohort a correct diagnosis of myelodysplastic syndrome was formulated in 198/281 cases (sensitivity 70%), while 18 false-positive results were noted among 257 controls (specificity 93%). Sixty-five percent of patients without specific markers of dysplasia (ring sideroblasts and clonal cytogenetic abnormalities) were correctly classified. A high value of the flow cytometric score was associated with multilineage dysplasia (P=0.001), transfusion dependency (P=0.02), and poor-risk cytogenetics (P=0.04). The sensitivity and specificity in the validation cohort (69% and 92%, respectively) were comparable to those in the learning cohort. The likelihood ratio of the flow cytometric score was 10. CONCLUSIONS: A flow cytometric score may help to establish the diagnosis of myelodysplastic syndrome, especially when morphology and cytogenetics are indeterminate.

Implementation of flow cytometry in the diagnostic work-up of myelodysplastic syndromes in a multicenter approach: report from the Dutch Working Party on Flow Cytometry in MDS.

Flow cytometry (FC) is recognized as an important tool in the diagnosis of myelodysplastic syndromes (MDS) especially when standard criteria fail. A working group within the Dutch Society of Cytometry aimed to implement FC in the diagnostic work-up of MDS. Hereto, guidelines for data acquisition, analysis and interpretation were formulated. Based on discussions on analyses of list mode data files and fresh MDS bone marrow samples and recent literature, the guidelines were modified. Over the years (2005-2011), the concordance between the participating centers increased indicating that the proposed guidelines contributed to a more objective, standardized FC analysis, thereby ratifying the implementation of FC in MDS.