The prognostic value of maturation-associated phenotypic abnormalities in myelodysplastic syndromes

A simple score derived from bone marrow immunophenotyping is important for prognostic evaluation in myelodysplastic syndromes

Immunophenotyping of bone marrow (BM) precursors has been used as an ancillary diagnostic tool in myelodysplastic syndromes (MDS), but there is no general agreement about which variables are the most relevant for prognosis. We developed a parsimonious prognostic model based on BM cell populations well-defined by phenotype. We analyzed 95 consecutive patients with primary MDS diagnosed at our Institution between 2005 and 2012 where BM immunophenotyping had been performed at diagnosis. Median follow-up: 42 months (4-199). Median age: 67 years (33-79). According to IPSS-R, 71 cases were low or intermediate risk. Flow variables significant in the univariate Cox analysis: "%monocytes/TNCs", "% CD16⁺ monocytes/TNCs", "total alterations in monocytes", "% myeloid CD34⁺ cells", "number of abnormal expressions in myeloblasts" and "% of B-cell progenitors". In the multivariate model remained independent: "% myeloid CD34⁺ cells", B-cell progenitors" and "% CD16⁺ monocytes/TNCs". These variables were categorized by the extreme quartile risk ratio strategy in order to build the score: % myeloid CD34⁺ cells" (≥ 2.0% = 1 point), B-cell progenitors" (< 0.05% 1 point) and "CD16⁺ monocytes/TNCs" (≥ 1.0% 1 point). This score could separate patients with a different survival. There was a weak correlation between the score and IPSS-R. Both had independent prognostic values and so, the flow score adds value for the prognostic evaluation in MDS.

The myelodysplastic syndromes flow cytometric score: a three-parameter prognostic flow cytometric scoring system

The prognosis of myelodysplastic syndromes (MDS) is currently estimated by using the revised International Prognostic Scoring System (IPSS-R). Several studies have shown that further refinement of prognostication for MDS can be achieved by adding flow cytometric parameters. However, widespread implementation of flow cytometry for the prognosis of MDS is hampered by complexity of the analysis. Therefore, the aim of this study was to construct a robust and practical flow cytometric score that could be implemented as a routine procedure. To achieve this, bone marrow aspirates of 109 MDS patients were analyzed by flow cytometry. A second cohort consisting of 103 MDS patients was used to validate the MDS flow cytometric score (MFS). The parameters forming the MFS were sideward light scatter and CD117 expression of myeloid progenitor cells and CD13 expression on monocytes. Three MFS risk categories were formed. Patients with MDS and intermediate MFS scores had significantly better overall survival (OS) compared with the patients with high MFS scores. The MFS further refined prognostication within the IPSS-R low-risk category, by identifying patients with worse OS in case of high MFS. In conclusion, a practical three parameter flow cytometric prognostic score was constructed enabling further refinement of prognostication of MDS.

Improving the differential diagnosis between myelodysplastic syndromes and reactive peripheral cytopenias by multiparametric flow cytometry: the role of B-cell precursors

Background

Immunophenotyping is a valuable ancillary technique for the differential diagnosis between myelodysplastic syndromes (MDS) with low bone marrow (BM) blast counts and a normal karyotype, and reactive peripheral (PB) cytopenias. Our aim was to search for the most important variables for this purpose. We also analyzed the age variation of BM B-cell precursors (BCP) and its differences in reactive and clonal cytopenias.

Methods

Immunophenotypic analyzes were performed in BM of 54 patients with MDS (76% with BM blasts <5%) and 35 cases of reactive cytopenias. Healthy allogeneic BM transplantation donors (n = 41) were used as controls. We used a four-color panel of antibodies analyzing 9 granulocytic, 8 monocytic and 6 CD34⁺ cell features.

Results

Asynchronous shift to the left in maturing granulocytes and increase in CD16⁺ monocytes were also found in reactive PB cytopenias, but the most important aberrancies in MDS were seen in myeloid CD34⁺ cells. Decrease in BCP, that is a hallmark of MDS, could also be found in reactive cytopenias, especially in patients >55 years. % BM BCP could be calculated by the formula: (−7.97 × log age) + (4.24 × log % CD34⁺cells) – (0.22 x nr. alterations CD34⁺cells) + 0.577. Corrected R² = 0.467.

Conclusion

Analysis of myelomonocytic precursors and CD34⁺ cells was satisfactory for the differential diagnosis between reactive PB cytopenias and MDS. The most specific alterations were found in CD34⁺ cells. Comparison of the values obtained with those of normal age-matched controls is recommended.

Bone marrow immunophenotyping by flow cytometry in refractory cytopenia of childhood

Refractory cytopenia of childhood is the most common type of childhood myelodysplastic syndrome. Because the majority of children with refractory cytopenia have a normal karyotype and a hypocellular bone marrow, differentiating refractory cytopenia from the immune-mediated bone marrow failure syndrome (very) severe aplastic anemia can be challenging. Flow cytometric immunophenotyping of bone marrow has been shown to be a valuable diagnostic tool in differentiating myelodysplastic syndrome from non-clonal cytopenias in adults. Here, we performed the first comprehensive flow cytometric analysis of immature myeloid, lymphoid cells and erythroid cells, and granulocytes, monocytes, and lymphoid cells in bone marrow obtained from a large prospective cohort of 81 children with refractory cytopenia. Children with refractory cyotopenia had a strongly reduced myeloid compartment, but not as severe as children with aplastic anemia. Furthermore, the number of flow cytometric abnormalities was significantly higher in children with refractory cytopenia than in healthy controls and in children with aplastic anemia, but lower than in advanced myelodysplastic syndrome. We conclude that flow cytometric immunophenotyping could be a relevant addition to histopathology in the diagnosis of refractory cytopenia of childhood. (The multi-center studies EWOG-MDS RC06 and EWOG-MDS 2006 are registered at clinicaltrials.gov identifiers 00499070 and 00662090, respectively).

Immunophenotyping in myelodysplastic syndromes can add prognostic information to well-established and new clinical scores

Background

myelodysplastic syndromes (MDS) are a heterogeneous group of hematopoietic clonal disorders. So, prognostic variables are important to separate patients with a similar biology and clinical outcome. We compared the importance of risk stratification in primary MDS of IPSS and WPSS with the just described revision of IPSS (IPSS-R), and examined if variables obtained by bone marrow immunophenotyping could add prognostic information to any of the scores.

Methods

In this prospective study of 101 cases of primary MDS we compared the relation of patients’ overall survival with WHO types, IPSS, IPSS-R, WPSS and phenotypic abnormalities of hematopoietic precursors. We examined aberrancies in myelomonocytic precursors and CD34⁺ cells. Patients were censored when receiving chemotherapy or BM transplantation. Survival analysis was made by Cox regressions and stability of the models was examined by bootstrap resampling.

Results

median age: 64 years (15–93). WHO types: 2 cases of 5q- syndrome, 7 of RA, 64 of RCDM and 28 of RAEB. In the univariate Cox analysis, increasing risk category of all scores, degree of anemia, higher percentage of BM blasts, higher number of CD34⁺ cells and their myeloid fractions besides increasing number of phenotypic abnormalities detected were significantly associated with a shorter survival. In the multivariate analysis comparing the three scores, IPSS-R was the only independent risk factor. Comparing WPSS with phenotypic variables (CD34⁺/CD13⁺ cells, CD34⁺/CD13⁻ cells and “total alterations”) the score and “CD34⁺/CD13⁺ cells” remained in the model. When IPSS was tested together with these phenotypic variables, only “CD34⁺/CD13⁺ cells”, and “total alterations” remained in the model. Testing IPSS-R with the phenotypic variables studied, only the score and “CD34⁺/CD13⁺ cells” entered the model.

Conclusions

Immunophenotypic analysis of myelomonocytic progenitors provides additional prognostic information to all clinical scores studied. IPSS-R improved risk stratification in MDS compared to the former scores.

Altered immunophenotypic features of peripheral blood platelets in myelodysplastic syndromes

BACKGROUND

Multiparameter flow cytometric analysis of bone marrow and peripheral blood cells has proven to be of help in the diagnostic workup of myelodysplastic syndromes. However, the usefulness of flow cytometry for the detection of megakaryocytic and platelet dysplasia has not yet been investigated. The aim of this pilot study was to evaluate by flow cytometry the diagnostic and prognostic value of platelet dysplasia in myelodysplastic syndromes.

DESIGN AND METHODS

We investigated the pattern of expression of distinct surface glycoproteins on peripheral blood platelets from a series of 44 myelodysplastic syndrome patients, 20 healthy subjects and 19 patients with platelet alterations associated to disease conditions other than myelodysplastic syndromes. Quantitative expression of CD31, CD34, CD36, CD41a, CD41b, CD42a, CD42b and CD61 glycoproteins together with the PAC-1, CD62-P, fibrinogen and CD63 platelet activation-associated markers and platelet light scatter properties were systematically evaluated.

RESULTS

Overall, flow cytometry identified multiple immunophenotypic abnormalities on platelets of myelodysplastic syndrome patients, including altered light scatter characteristics, over-and under expression of specific platelet glycoproteins and asynchronous expression of CD34; decreased expression of CD36 (n = 5), CD42a (n = 1) and CD61 (n = 2), together with reactivity for CD34 (n = 1) were only observed among myelodysplastic syndrome cases, while other alterations were also found in other platelet disorders. Based on the overall platelet alterations detected for each patient, an immunophenotypic score was built which identified a subgroup of myelodysplastic syndrome patients with a high rate of moderate to severe alterations (score>1.5; n = 16) who more frequently showed thrombocytopenia, megakaryocytic dysplasia and high-risk disease, together with a shorter overall survival.

CONCLUSIONS

Our results show the presence of altered phenotypes by flow cytometry on platelets from around half of the myelodysplastic syndrome patients studied. If confirmed in larger series of patients, these findings may help refine the diagnostic and prognostic assessment of this group of disorders.

Review of the relevance of aberrant antigen expression by flow cytometry in myeloid neoplasms

This article reviews the use of aberrant antigen expression detected by flow cytometry in the diagnosis and clinical handling of acute myeloid leukaemia (AML) and the myelodysplastic syndromes (MDS). Such aberrancies offer a valuable tool for the proper classification of these myeloid malignancies according the World Health Organization 2008 classification. Aberrant antigen expression by flow cytometry is also important for prognostification. This review supports the view, that minimal residual disease detection methods that make use of such aberrancies should be part of the routine management of AML patients to guide therapy, but also suggests the introduction of flow cytometry in MDS for diagnosis and treatment decisions in the near future.

High-level CD34 expression on megakaryocytes independently predicts an adverse outcome in patients with myelodysplastic syndromes

Expression of CD34 on mature-appearing megakaryocytes can be seen in various intrinsic bone marrow (BM) disorders as well as reactive bone marrows. In this study we investigate the clinical significance of CD34+ megakaryocytes in myelodysplastic syndromes (MDSs). Expression of CD34 on megakaryocytes was assessed on BM biopsies obtained from 202 patients with MDS. High-level (≥20%) CD34 expression on megakaryocytes was found in BM of 29 patients (14%). The expression of CD34 on megakaryocytes is correlated with severe cytopenia, higher numbers of myeloblasts, more frequent and higher risk cytogenetic abnormalities, and a shorter overall survival. Multivariate analysis indicated that the expression of CD34 on megakaryocytes could be a strong and an independent poor prognostic factor in MDS, with a hazard ratio of 2.53.

Germ plasm-like Dot cells maintain their wound regenerative function after in vitro expansion

1. Wounds in fetal skin heal without scarring; however, the mechanism for this is unknown. We have identified a novel group of protein and nucleotides-positive particles in fetal and adult mouse blood and in human blood, and termed them 'Dot cells'. Freshly isolated Dot cells regenerate wounds with less scarring and can be cultured without feeder layers. 2. Because the morphology of Dot cells has never been described, in the present study we describe the specific characterizations of Dot cells, including their growth pattern in vitro, and their expressions of stem cell markers using fluorescent cell sorting analyses and immunofluorescent histology. Our data indicates that cultured Dot cells express stem cell surface markers and embryonic stem cell transcription markers, such as Oct4, Nanog and Sox-2. In addition, Dot cells express VASA, the germ plasm specific marker. 3. To confirm whether Dot cells maintain their wound regenerative activity after in vitro expansion, in vitro cultured Dot cells were transplanted to wounded mice. Dot cells from albino mice maintain their wound regenerative activities after intravenous transplantation to black-background diabetic mice. In addition, Dot cells regenerate both the epithelial and dermal cells in the wounds of wild-type mice. The regenerated hair follicles, smooth muscle and dermal tissues express transiently to VASA. 4. Our data demonstrate that Dot cells are newly identified organisms located in the blood and bone marrow of mammals. They express germ cell, embryonic stem cell and adult stem cell markers. Dot cells maintain their regenerative function after in vitro expansion.

Diagnostic tools in the indications for allogeneic stem cell transplantation in myelodysplastic syndromes

The rates of allogeneic stem cell transplantation (SCT) to treat the myelodysplastic syndromes (MDS) is continually increasing. However, given the growing arsenal of therapeutic options in parallel to deeper insight into the heterogeneity of this disorder, determining the indications for SCT in MDS remains a difficult task. The International Prognostic Scoring System (IPSS) serves as a guideline for therapeutic decisions, but many aspects (eg, interpretation of rare cytogenetic abnormalities, combinations of chromosomal alterations and/or molecular markers, variant clinical courses within distinct biological subgroups) remain the subject of continuous investigation. In an effort to achieve a more well-differentiated risk categorization, attempts have been made to perform a more detailed cytogenetic categorization, and the use of various fluorescein in situ hybridization (FISH) techniques has improved the description of aberrations. Multicenter initiatives have standardized multiparameter flow cytometry techniques for diagnosis of MDS. In advanced MDS, screening for molecular mutations can identify cases with a high transformation risk. Finally, the new World Health Organization classification system provides a more homogenous morphological categorization of MDS compared with the former French-American-British system. Consequently, in the near future, risk stratification in MDS might incorporate additional diagnostic tools and categorization systems aimed at improving the timing and indication for SCT in this complex disorder.