Myelodysplastic syndromes according to FAB and WHO classification. Single center experience

The results of clinical and laboratory observations of 119 MDS patients divided acc. to FAB, and - after excluding RAEB-t and CMML groups -- of 95 patients divided accordingly to WHO classification are presented. The diagnosis of MDS was based on medical interview, physical examination, blood biochemistry, peripheral blood (PB) and bone marrow (BM) cytomorphology and cytochemistry, trephine biopsy and cytogenetic examination. All hematologic examinations were done according to routine methods. Cytogenetic analyses were carried out on BM cells from 24-48 h cultures in standard conditions. At least 15-20 GTG-banded metaphases were analyzed in every patient. The survival time (ST) of patients differed significantly between the FAB or WHO groups, with p=0.0004 for FAB and p=0.02 for WHO. The progression to AML was more common in less favorable groups, with p=0.0001 for FAB and p=0.00016 for WHO. The distribution of IPSS prognostic index among the groups showed statistically significant difference (p=0.0004 for FAB, and p=0.0001 for WHO), whereas the distribution of karyotypic abnormalities did not. However, in univariate analysis statistically significant influence on ST showed, beside the both classification systems: cytogenetics, the presence of blasts in PB, age and IPSS index. In multivariate analysis the sole independent prognostic factors were: PB blasts and cytogenetics. The authors conclude that the WHO classification offers a good prognostic tool for MDS patients. However, the karyotype and the presence of blasts in PB should always be taken into account.     

Mutation of Ki-ras and N-ras oncogenes in myelodysplastic syndromes

Somatic mutation of the N-ras oncogene occurs frequently in de novo acute myeloid leukemia (AML). By virtue of their relation to AML, myelodysplastic syndromes (MDS) provide an in vivo model of human leukemogenesis. By using a strategy for analysis of gene mutation based on in vitro amplification of target sequences by the polymerase chain reaction (PCR) and selective oligonucleotide hybridization we analyzed the mutational status of codons 12, 13, and 61 of Ha-ras, K-ras, and N- ras in peripheral blood (PB) and/or bone marrow (BM) in 34 cases of primary MDS. Mutations at codon 12 of Ki-ras or N-ras were detected in three cases (9%): one of six cases of refractory anemia with excess blasts (RAEB) and two of nine cases of chronic myelomonocytic leukemia (CMML). The nucleotide substitution differed in each. In all cases the mutant allele was detectable in PB cells. A sustained hematologic remission was achieved after low-dose cytarabine therapy in the case of RAEB. Neither case of CMML exhibited signs of disease progression during follow-up at 7 and 12 months. In contrast, four of 31 patients without the ras mutation underwent transformation to AML within 12 months of genetic analysis. We conclude that ras mutations in MDS are heterogeneous and may develop at an early stage during the evolution of MDS. Their detection in PB cells illustrates the potential utility of ras mutation as a clonal marker in myeloid malignancy.     

Myelodysplastic syndromes, from French-American-British to World Health Organization: comparison of classifications on 431 unselected patients from a single institution.

In 1999 a working group of the World Health Organization (WHO) published a revised classification for myelodysplastic syndromes (MDS): RA, RARS, refractory cytopenia with multilineage dysplasia (RC+Dys), RAEB I and II, del (5q) syndrome, and MDS unclassifiable. Chronic myelomonocytic leukemia (CMML) and RAEB-t were excluded. Standard French-American-British (FAB) and new WHO classifications have been compared in a series of patients (n = 431) from a single center, analyzing morphologic, clinical, and cytogenetic data. According to the WHO findings, dysgranulocytopoiesis or dysmegakaryocytopoiesis only were found in 26% of patients with less than 5% medullary blasts. These patients are thus unclassified and should remain in the subgroups RA and RARS. Splitting of heterogeneous RAEB into 2 subgroups according to blast count was supported by a trend to a statistically significant difference in the single-center study population. Patients with CMML whose white blood cell counts are above 13 000/microL may be excluded from the MDS classification, as warranted by WHO, but a redistribution of patients with dysplastic CMML according to medullary blast count leads to more heterogeneity in other WHO subgroups. Although the natural courses of RAEB-T and acute myeloid leukemia (AML) with dysplasia are different, comparable median survival durations after treatment in patients with RAEB-T and AML were in favor of the proposed 20% medullary blast threshold for AML. The homogeneity of subgroups was studied by evaluating prognostic scores. A significant shift into lower IPSS risk groups was evident in the new classification. These data cannot provide evidence for the new WHO proposal, which should not be adopted for routine clinical use at present. Some of its aspects can provide a starting point for further studies involving refined cytogenetics and clinical results.     

A clinical study on myelodysplastic syndrome. Report of 64 cases

Systematic clinical and laboratory observations of 64 cases of myelodysplastic syndrome (MDS) were made. The results showed that malignant clone already exists in the bone marrow of patients with MDS. Eighteen cases of them have transformed into AML. The rates of transforming into AML in RAEB, RAEB-T and CMML were markedly higher than that in RA. The courses of MDS which transformed into AML from the various types were different. The transformation in RA was obviously longer than those in RAEB and RAEB-T. Two cases transformed into myelofibrosis. Diagnosis of CMML according to the FAB classification criteria revealed that it has two forms. One shows only increase of mature monocytes and it has no relation with the types of acute leukemia to be transformed. It is considered as a reactive monocytosis. The other form, in addition to increase of mature monocytes, also has increase of a few monoblasts and promonocytes. These are considered as true CMML and usually quickly developed into M4 or M5 which are related with monocytes.     

CBL mutation in chronic myelomonocytic leukemia secondary to familial platelet disorder with propensity to develop acute myeloid leukemia (FPD/AML)

Familial platelet disorder with a propensity to develop acute myeloid leukemia (FPD/AML) is a rare autosomal dominant disease characterized by thrombocytopenia, abnormal platelet function, and a propensity to develop myelodysplastic syndrome (MDS) and AML. So far, > 20 affected families have been reported. Recently, a second RUNX1 alteration has been reported; however, no additional molecular abnormalities have been found so far. We identified an acquired CBL mutation and 11q-acquired uniparental disomy (11q-aUPD) in a patient with chronic myelomonocytic leukemia (CMML) secondary to FPD with RUNX1 mutation but not in the same patient during refractory cytopenia. This finding suggests that alterations of the CBL gene and RUNX1 gene may cooperate in the pathogenesis of CMML in patients with FPD/AML. The presence of CBL mutations and 11q-aUPD was an important "second hit" that could be an indicator of leukemic transformation of MDS or AML in patients with FPD/AML.     

Flow cytometry immunophenotypic findings in chronic myelomonocytic leukemia and its utility in monitoring treatment response

Chronic myelomonocytic leukemia (CMML) is a myelodysplastic/myeloproliferative neoplasm, characterized by persistent monocytosis. Due to the lack of unique surface markers expressed by neoplastic monocytes and the frequent CD34‐negative blast immunophenotype, the diagnostic value of flow cytometric immunophenotyping (FCI) in CMML is rarely studied. In this study, by using a multicolor FCI assay, we assessed bone marrow (BM) immunophenotypical alterations in 118 CMML patients and follow‐up BM samples in 35 of these patients. The median BM monocytes as determined by FCI were 14% (1–63%), correlated with morphologic count (P = 0.0004). FCI alterations in monocytes were observed in 96% and granulocytes in 83% of cases. The percentage of CD34⁺ myeloblasts by FCI was low [median 0.6% (0.02–12.6%)], but exhibiting frequent aberrancies [median 6 (2–12)]. CD34⁺ B‐cell precursors were absent in 93% of cases. In 35 patients with follow‐up BM samples assessed, the CD34⁺ myeloblasts showed persistent FCI aberrancies in all 29 patients treated with hypomethylating agents and 3 patients on observation, but became normal in 3 patients following stem cell transplant. In conclusion, CMML exhibit numerous FCI alterations in monocytes, granulocytes, and more profound/frequent in CD34⁺ myeloblasts. These findings provide solid evidence for using FCI as an ancillary test in CMML diagnosis and also, in assessment of treatment responses.     

Phenotypic subtypes of leukaemic transformation in chronic myelomonocytic leukaemia

Chronic myelomonocytic leukaemia (CMML) is a haematological disorder with high risk of transformation to acute myeloid leukaemia (AML). To characterize the phenotypic and genomic patterns of CMML progression, we evaluated a cohort of 189 patients with AML evolving from CMML. We found that transformation occurs through distinct trajectories characterized by genomic profiles and clonal evolution: monocytic (Mo-AML, 53%), immature myeloid (My-AML, 43%) or erythroid (Ery-AML, 2%). Mo-AML, characterized by expansion of monoblasts and promonocytes (low CD34, CD117 expression; high CD14, CD33, CD56 and CD64 expression), were defined by SRSF2, TET2 and RAS pathway mutation co-dominance and were more likely to evolve from SRSF2-TET2 co-mutant CMML through emergence/expansion of RAS pathway mutant clones. Conversely, My-AML, characterized by expansion of immature myeloid blasts (high frequency of CD34, CD38, CD117; low frequency of CD14, CD64 and CD56 expression) were less likely to exhibit SRSF2-TET2 co-mutations or RAS pathway mutations and had higher frequency of CEBPA mutations. Ery-AML was defined by complex karyotypes and TP53 mutations. A trend towards improved OS and EFS with hypomethylating agent-venetoclax combination was observed in My-AML, but not Mo-AML. These findings define distinct progression of CMML and set the basis for future studies evaluating the role of phenotype-specific therapeutics.     

Functional response of leukaemic blasts to stromal cell-derived factor-1 correlates with preferential expression of the chemokine receptor CXCR4 in acute myelomonocytic and lymphoblastic leukaemia

The chemokine stromal cell-derived factor-1 (SDF-1) that is released by bone marrow (BM) stromal cells and contributes to stem cell homing may also play a role in the trafficking of leukaemic cells. We analysed SDF-1-induced intracellular calcium fluxes in leukaemic blasts from the peripheral blood of patients with newly diagnosed acute myeloid leukaemia (AML) and lymphoblastic leukaemia (B-lineage ALL), determined the effect of BM stromal cell-conditioned medium on in vitro transendothelial migration (TM) and measured expression of the SDF-1 receptor, CXCR4, by flow cytometry. AML FAB M1/2 blasts did not show calcium fluxes and TM was not stimulated. In myelomonocytic AML (M4/5), however, SDF-1 induced significant calcium fluxes and TM was increased twofold by the conditioned medium. M3 and M4 blasts with eosinophilia (M4eo) showed intermediate activity and M6 blasts showed no functional activity. In ALL, strong calcium fluxes and increased TM (2.5-fold) were observed. Accordingly, expression of CXCR4 was low in undifferentiated (M0) AML, myeloid (M1/2) AML and erythroid (M6) AML, but high [mean fluorescence (MF) > 50] in promyelocytic (M3) AML, myelomonocytic (M4/5) AML and B-lineage ALL. We conclude that, in AML, SDF-1 is preferentially active in myelomonocytic blasts as a result of differentiation-related expression of CXCR4. Functional activity of SDF-1 and high expression of CXCR4 in B-lineage ALL is in accordance with the previously described activity of SDF-1 in early B cells. SDF-1 may contribute to leukaemic marrow infiltration, as suggested by increased CXCR4 expression and migratory response in BM-derived blasts compared with circulating cells.     

Relative increase in leukemia-specific DNA in peripheral blood plasma from patients with acute myeloid leukemia and myelodysplasia

Using loss of heterozygosity (LOH) and X-chromosome inactivation, we compared peripheral blood (PB) plasma with bone marrow (BM) cells in detecting genomic abnormalities in patients with acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS). We detected LOH in the PB plasma of all 45 patients who had cytogenetically documented chromosomal abnormalities (5q-, 7-, +8, 17-, or 20-). BM cells from the same patients showed LOH in 89% of patients with MDS and 70% of patients with AML. Posttherapy samples from 16 of these patients demonstrated complete concordance between LOH and cytogenetics in detecting residual disease in 15 samples. Of the 16 samples, 4 showed LOH in plasma with normal BM morphology. Using X-chromosome inactivation, clonality was detectable in 19 (73%) of 26 BM samples, whereas all PB plasma samples showed clonality. These data support the conclusion that PB plasma is enriched by tumor-specific DNA and can replace BM cells for studying genomic abnormalities.     

Clonal analysis of myelodysplastic syndromes: evidence of multipotent stem cell origin

Restriction fragment length polymorphisms (RFLPs) of the X-chromosome genes hypoxanthine phosphoribosyl transferase (HPRT) and phosphoglycerate kinase (PGK) were studied in 34 female patients with primary myelodysplastic syndromes (MDS). Twelve patients (35%) were heterozygous at the HPRT or PGK loci for BamHI or BglI RFLPs, respectively. In eight patients showing PGK polymorphisms, clonality was determined by X-chromosome inactivation analysis. These included patients from different morphologic subtypes: four with refractory anemia (RA), two with RA and ring sideroblasts (RARS), one patient with RA with excess of blasts (RAEB), and one with chronic myelomonocytic leukemia (CMML). A monoclonal pattern of X-chromosome inactivation was observed in seven cases. In a further case characterized by bone marrow hypoplasia, peripheral blood (PB) leukocytes were polyclonal in origin. Following low-dose cytarabine therapy, reversion to polyclonal hematopoiesis was observed in a case of RAEB indicating the presence of residual normal hematopoietic stem cells with the capacity for marrow reconstitution. The clonal relation of lymphoid and granulocyte/monocyte lineages was studied directly in two cases of CMML exhibiting somatic mutations of N-ras or Ki-ras oncogenes. By selective oligonucleotide hybridization to ras gene sequences amplified in vitro by the polymerase chain reaction, a mutated ras allele was demonstrated in PB granulocytes, monocytes, and B and T lymphocytes of both patients. We conclude that MDS arise from a multipotent hematopoietic stem cell with the potential for myeloid and lymphoid differentiation.     

Malignant progenitors from patients with CD87+ acute myelogenous leukemia are sensitive to a diphtheria toxin-urokinase fusion protein

In previous studies, we demonstrated that the diphtheria toxin-urokinase fusion protein DTAT was selectively toxic to acute myeloid leukemia (AML) cell lines overexpressing the CD87 urokinase receptor. In the present study, we analyzed the sensitivity of patient leukemic progenitors to DTAT and correlated the sensitivity with CD87 expression.We isolated leukemic blasts by density gradient centrifugation and performed immunophenotyping by flow cytometry and blast sensitivity measurements by inhibition of cell proliferation and colony formation in semisolid media.We found CD87 overexpression in 18 (25%) of 71 patient leukemic blast samples, including 18 (28%) of 64 myeloid malignancies and 0 (0%) of 7 lymphoid malignancies. DTAT was toxic to patient leukemic blasts by both proliferation inhibition (IC50 85% inhibition by 10 nM DTAT in 11/41 evaluable samples). Only AML and chronic myeloid leukemia (CML) blast crisis blasts (18/61 [30%]) were sensitive to DTAT by the proliferation inhibition assay. Lymphoid leukemia and chronic phase CML/chronic myelomonocytic leukemia (CMML) progenitors were insensitive to DTAT by the proliferation inhibition assay (n = 7 and n = 3, respectively). Similarly, normal marrow progenitors were insensitive to DTAT by both proliferation inhibition (n = 2) and colony inhibition (n = 5) assays. The DTAT toxicity measured by both proliferation inhibition assay and colony inhibition assay correlated with CD87 density (p < 0.0001 and p = 0.001, respectively). DTAT toxicity results were similar for leukemic blasts measured by either of the two assays (p = 0.0002).This study provides the first evidence that a urokinase receptor targeted diphtheria fusion protein is toxic to patient AML blasts. The work also suggests that blast proliferation assays yield similar responses to leukemia colony-forming cell colony assays.     

Blast transformation in chronic myelomonocytic leukemia: Risk factors,genetic features,survival, and treatment outcome

Among 274 patients with chronic myelomonocytic leukemia (CMML) and followed for a median of 17.1 months, blast transformation (BT) occurred in 36 (13%). On multivariable analysis, risk factors for BT were presence of circulating blasts (HR 5.7; 95% CI 2.8–11.9) and female gender (HR 2.6; 95% CI 1.3–5.1); the results remained unchanged when analysis was restricted to CMML‐1. ASXL1/SRSF2/SF3B1/U2AF1/SETBP1 mutational frequencies were not significantly different between time of CMML diagnosis and BT. Median survival post‐BT was 4.7 months (5‐year survival 6%) and better with allogeneic stem cell transplant (SCT) (14.3 months vs. 4.3 months for chemotherapy vs. 0.9 months for supportive care; P = 0.03). Neither karyotype nor mutational status was independently associated with risk of BT or post‐BT survival. We conclude that female patients with CMML and those with circulating blasts are at a higher risk of BT. Post‐BT survival is dismal and our observations suggest consideration of allogeneic SCT prior to BT.Am. J. Hematol. 90:411–416, 2015. © 2015 Wiley Periodicals, Inc.     

Expression of EVI1 in myelodysplastic syndromes and other hematologic malignancies without 3q26 translocations

The EVI1 gene encodes a zinc-finger, DNA-binding protein originally described as the transforming gene associated with a common ecotropic viral insertion site in myeloid leukemias. Previous studies demonstrated EVI1 expression in human leukemias in cases with 3q26 translocations, but not in normal blood or bone marrow. These studies also suggested an association between EVI1 expression and chromosome 7 deletion (del). Because of this association, we examined expression of EVI1 using RNA polymerase chain reaction (PCR) in patients with myelodysplastic syndromes (MDS) and acute leukemia with and without 3q26 translocations. EVI1 RNA was expressed in 29% of 34 (95% confidence interval, 20% to 50%) patients with the MDS subtypes refractory anemia (RA), refractory anemia with excess blasts (RAEB), or refractory anemia with excess blasts in transformation (RAEB-T). The vast majority of these cases occurred in patients with RAEB and RAEB-T. EVI1 expression was not detected in patients with chronic myelomonocytic leukemia (CMML), normal bone marrow or cord blood, or a variety of other hematologic malignancies. EVI1 RNA was detected in three of 18 patients with acute myelogenous leukemia (AML) and in two of four patients with acute promyelocytic leukemia (APL). Karyotypes showed that only one AML patient had karyotype 3q26 abnormalities, indicating that EVI1 expression is associated with cases that do not have structural abnormalities involving chromosome 3q26. These studies document for the first time the abnormal expression of EVI1 RNA by patients with MDS, and suggest an important role for EVI1 in the pathogenesis or progression of some myeloid malignancies.     

Monosomal karyotype in adult acute myeloid leukemia: prognostic impact and outcome after different treatment strategies

We aimed to determine the prognostic impact of monosomal karyotype (MK) in acute myeloid leukemia (AML) in the context of the current World Health Organization (WHO) classification and to evaluate the outcome of MK(+) patients after allogeneic HSCT. Of 1058 patients with abnormal cytogenetics, 319 (30%) were MK MK(+). MK(+) patients were significantly older (P = .0001), had lower white blood counts (P = .0006), and lower percentages of BM blasts (P = .0004); MK was associated with the presence of -5/5q-, -7, 7q-, abnl(12p), abnl(17p), -18/18q-, -20/20q-, inv(3)/t(3;3), complex karyotype (CK), and myelodysplasia (MDS)-related cytogenetic abnormalities (P < .0001, each); and NPM1 mutations (P < .0001), FLT3 internal tandem duplications (P < .0001), and tyrosine kinase domain mutations (P = .02) were less frequent in MK(+). Response to induction therapy and overall survival in MK(+) patients were dismal with a complete remission rate of 32.5% and a 4-year survival of 9%. MK retained its prognostic impact in AML with CK, AML with MDS-related cytogenetic abnormalities, and in a revised definition (MK-R) excluding cases with recurrent genetic abnormalities according to WHO classification and those with derivative chromosomes not leading to true monosomies. In younger patients, allogeneic HSCT from matched related and unrelated donors resulted in a limited improvement of overall survival.     

Immunophenotypic clustering of myelodysplastic syndromes

Myelodysplastic syndromes (MDSs) are heterogeneous diseases of bone marrow (BM) cell precursors for which immunophenotypic characterization is still considered irrelevant despite the accuracy and sensitivity of flow cytometry techniques. The aim of this study was to determine whether immunophenotypic abnormalities could be defined in MDSs and could correlate with the French-American-British classification and cytogenetics. Analysis was performed on 275 BM samples (207 MDS patients, 68 controls) and 25 control blood samples. Immunophenotyping was based on a primary gating of blast cells, monocytes, and granulocytes according to CD45 antigen expression and side scatter light diffraction. Immunophenotypic hierarchical clustering was performed to analyze the results. The data obtained show that (1) immunophenotypic clustering partly discriminates patients with refractory anemia with excess blasts/refractory anemia with excess blasts in transformation (RAEB/RAEB-T), chronic myelomonocytic leukemia (CMML), and refractory anemia/refractory anemia with ring sideroblasts (RA/RARS) for CD45(lo) blast cells and patients with RA/CMML, RARS, and RAEB/RAEB-T for CD45(hi)/side scatter(hi) (SS(hi)) granulocytes; (2) the most discriminating markers were CD16, CD34, CD36, CD38, CD71, and HLA-DR for blast cells and CD11b, CD13, CD33, CD36, CD38, CD71, and HLA-DR for CD45(hi)/SS(hi) granulocytes; (3) clusters related to CD34 expression were associated with high levels of blast cells on BM smear; (4) clusters related to high levels of CD36 expression on CD45(lo) blast cells and CD45(hi)/SS(hi) granulocytes were associated with a poor International Prognosis Scoring System score; and (5) high levels of CD71 expression on CD45(hi)/SS(hi) granulocytes were associated with the RARS category. These results show a close relationship between immunophenotypic abnormalities and BM dysplasia and suggest that flow cytometry could be a future tool for the characterization of MDSs.     

Classification of patients with myelodysplastic syndromes according to the FAB co-operative group's proposals Proposals for a redefinition of blast cell type II

53 patients with the myelodysplastic syndromes (MDS) were classified according to the proposals of the FAB cooperative group 1982. 29 patients had refractory anaemia (RA), 10 refractory anaemia with excess of blasts (RAEB), 5 RAEB in transformation, 7 RA with ringed sideroblasts and 2 chronic myelomonocytic leukaemia (CMML). Counting blast cells type I and II involved no difficulties. 4 of 15 patients who developed acute myeloid leukaemia (AML) according to the FAB classification of 1976 did not fulfill the new 1982 criteria for AML. A redefinitioon of the blast cell type II to include a more granulated blast cells, without the characteristics of promyelocytes, would solve this problem. We conclude that a redefinition of the blast cell type II might turn out to be useful.     

Myelodysplastic syndromes: analysis of 131 cases according to the FAB classification

The clinical and haematological findings in 131 patients with myelodysplastic syndromes (MDS), none of which had previously received chemotherapy or radiotherapy, classified according to the FAB criteria, were analysed. The distribution among the 5 subgroups was: RA 31 patients, RAS 19, RAEB 23, CMML 29 and RAEBT 29 patients. There were difficulties in the classification of 24 patients. These included, first, 8 cases with myeloid hyperplasia of the bone marrow (BM) but without monocytosis or excess of blasts of the BM. They were classified as RA. Second, 8 cases with sideroblastosis but with monocytosis or excess of blasts of the BM were classified 3 as RAEB, 2 as CMML and 3 as RAEBT. Finally, 8 cases with absolute monocytosis and BM blasts 15-30% were classified as CMML. 37 of 82 dead patients (45.1%) had transformed to acute non-lymphoblastic leukaemia (ANLL). The incidence of evolution to ANLL was low for RA and RAS (6.30% and 12.5% respectively), while it was 37.5% for RAEB, 57.1% for CMML and 77.2% for RAEBT. The median survival for each subgroup was: RA 18 months; RAS 25; RAEB 13; CMML 14 and RAEBT 10 months. It is concluded that the FAB classification with some modifications recognises group of MDS with different prognosis.     

Vascular endothelial cell growth factor is an autocrine promoter of abnormal localized immature myeloid precursors and leukemia progenitor formation in myelodysplastic syndromes

Vascular endothelial growth factor (VEGF) is a potent angiogenic peptide with biologic effects that include regulation of hematopoietic stem cell development, extracellular matrix remodeling, and inflammatory cytokine generation. To delineate the potential role of VEGF in patients with myelodysplastic syndrome (MDS), VEGF protein and receptor expression and its functional significance in MDS bone marrow (BM) were evaluated. In BM clot sections from normal donors, low-intensity cytoplasmic VEGF expression was detected infrequently in isolated myeloid elements. However, monocytoid precursors in chronic myelomonocytic leukemia (CMML) expressed VEGF in an intense cytoplasmic pattern with membranous co-expression of the Flt-1 or KDR receptors, or both. In situ hybridization confirmed the presence of VEGF mRNA in the neoplastic monocytes. In acute myelogenous leukemia (AML) and other MDS subtypes, intense co-expression of VEGF and one or both receptors was detected in myeloblasts and immature myeloid elements, whereas erythroid precursors and lymphoid cells lacked VEGF and receptor expression. Foci of abnormal localized immature myeloid precursors (ALIP) co-expressed VEGF and Flt-1 receptor, suggesting autocrine cytokine interaction. Antibody neutralization of VEGF inhibited colony-forming unit (CFU)-leukemia formation in 9 of 15 CMML and RAEB-t patient specimens, whereas VEGF stimulated leukemia colony formation in 12 patients. Neutralization of VEGF activity suppressed the generation of tumor necrosis factor-alpha and interleukin-1beta from MDS BM-mononuclear cells and BM-stroma and promoted the formation of CFU-GEMM and burst-forming unit-erythroid in methylcellulose cultures. These findings indicate that autocrine production of VEGF may contribute to leukemia progenitor self-renewal and inflammatory cytokine elaboration in CMML and MDS and thus provide a biologic rationale for ALIP and its adverse prognostic relevance in high-risk MDS.     

Incorporating flow cytometry and next-generation sequencing in the diagnosis of CMML. Are we ready for prime?

In the last version of the WHO classification of myeloid malignancies, flow cytometry and molecular investigation are listed as potentially useful, yet non-essential diagnostic tools in hard-to-recognize chronic myelomonocytic leukemias (CMML). Flow recognition of CMML was initially based on an increase in the fraction of peripheral blood, CD14⁺,CD16^- classical monocytes ≥94% of total monocytes. An associated inflammatory disease can preclude the detection of classical monocyte fraction increase by inducing accumulation of CD14⁺,CD16⁺ intermediate monocytes. In such a situation, decrease in the Slan⁺,CD14^low,CD16⁺ non-classical monocyte fraction below 1.7% still supports CMML diagnosis. This robust, two-step flow cytometry assay identifies CMML with a very high sensitivity. Otherwise, detection of one or several acquired gene mutations with high variant allele frequency supports the diagnosis of CMML, oligomonocytic CMML or clonal monocytosis of clinical significance. Together, recent investigations support integration of flow cytometry analysis of peripheral blood monocyte subsets and new generation sequencing of a panel of 20–30 recurrently mutated genes in the diagnostic work-up of CMML.