Acquired alpha-thalassemia in association with myelodysplastic syndrome and other hematologic malignancies

Abnormalities of hemoglobin synthesis are usually inherited but may also arise as a secondary manifestation of another disease, most commonly hematologic neoplasia. Acquired hemoglobin disorders can be seen in any population and are not restricted to areas of the world with high incidences of inherited hemoglobinopathies. In fact, the acquired hemoglobinopathies may be more readily recognized where inherited hemoglobin abnormalities are rare and less likely to cause diagnostic confusion. Acquired alpha-thalassemia is the best characterized of the acquired red blood cell disorders in patients with hematologic malignancy, and it is almost always associated with a myelodysplastic syndrome (MDS). At least 2 molecular mechanisms for acquired alpha-thalassemia are now recognized: acquired deletion of the alpha-globin gene cluster limited to the neoplastic clone and, more commonly, inactivating somatic mutations of the trans-acting chromatin-associated factor ATRX, which cause dramatic down-regulation of alpha-globin gene expression. Here we review the clinical, hematologic, and molecular genetic features of alpha-thalassemia arising in a clonal myeloid disorder, and we discuss howATRX might affect gene expression in normal and abnormal hematopoiesis through epigenetic mechanisms.     

Activation of EVI1 gene expression in human acute myelogenous leukemias by translocations spanning 300-400 kilobases on chromosome band 3q26.

Retroviral activation of Evi-1 gene expression is one of the most common transforming events in murine myeloid leukemias. To evaluate the role of the EVI1 gene in human acute myelogenous leukemia (AML), leukemic blasts or cell lines from 116 patients were examined. In eight patients the EVI1 gene was expressed and all but one had cytogenetically detectable translocations of chromosome 3q26 where the EVI1 gene has been localized. To identify breakpoints, a restriction map that spans 1700 kilobases (kb) of the EVI1 locus was developed by pulsed-field gel electrophoresis. In one case, t(3;3)(q21;q26), a rearrangement was localized to 170-330 kb 5' of the gene. In a second case, t(3;3)(q21;q26), there was a rearrangement 13 kb 5' of the gene. This rearrangement was cloned and shown to be due to the fusion of sequences from 3q21-22 with the EVI1 locus. In the third case, ins(3)-(q21q25q27), there was a rearrangement that mapped 150 kb downstream from the 5' end of the gene.     

High EVI1 levels predict adverse outcome in acute myeloid leukemia: prevalence of EVI1 overexpression and chromosome 3q26 abnormalities underestimated

Inappropriate expression of EVI1 (ecotropic virus integration-1), in particular splice form EVI1-1D, through chromosome 3q26 lesions or other mechanisms has been implicated in the development of high-risk acute myeloid leukemia (AML). To validate the clinical relevance of EVI1-1D, as well as of the other EVI1 splice forms and the related MDS1/EVI1 (ME) gene, real-time quantitative polymerase chain reaction was performed in 534 untreated adults with de novo AML. EVI1-1D was highly expressed in 6% of cases (n = 32), whereas 7.8% were EVI1⁺ (n = 41) when all splice variants were taken into account. High EVI1 predicted a distinctly worse event-free survival (HR = 1.9; P = .002) and disease-free survival (HR = 2.1, P = .006) following multivariate analysis. Importantly, we distinguished a subset of EVI1⁺ cases that lacked expression of ME (EVI1⁺ME^–; n = 17) from cases that were ME⁺ (EVI1⁺ME⁺; n = 24). The atypical EVI1⁺ME^– expression pattern exhibited cytogenetically detectable chromosomal 3q26 breakpoints in 8 cases. Fluorescence in situ hybridization revealed 7 more EVI1⁺ME^– cases that carried cryptic 3q26 breakpoints, which were not found in the EVI1⁺ME⁺ group. EVI1⁺ME^– expression predicts an extremely poor prognosis distinguishable from the general EVI1⁺ AML patients (overall survival [OS]: P < .001 and event-free survival [EFS]: P = .002). We argue that EVI1/ME quantitative expression analysis should be implemented in the molecular diagnostic procedures of AML.     

Detection of t(3 ; 21) (q26 ; q22) with AML1/EVI1 mRNA during progression of myelodysplastic syndrome to acute myeloid leukemia]

A 74-year-old woman had myelodysplastic syndrome (MDS) in 1986. In June 1994, she suffered exacerbation of pancytopenia with no chromosomal abnormalities, but AML1/EVI1 chimeric mRNA was detected by RT-PCR. Two months later, an increase in bone marrow blasts (5%) was noted, and chromosomal analysis detected t(3 ; 21) (q26 ; 22), del(7) (q22), del(11) (q23). In 1995, the marrow blasts increased to 30% and the patient died of disease progression. The AML1/EVI1 gene has been shown to cause blast crisis in chronic myelogenous leukemia. This case suggested that the AML1/EVI1 gene may be involved in the progression of MDS together with del(7) (q22) and del(11) (q23).     

EVI1 overexpression in t(3;17) positive myeloid malignancies results from juxtaposition of EVI1 to the MSI2 locus at 17q22

Chromosomal translocations involving the EVI1 locus are a recurrent finding in myeloid leukemia and are associated with poor prognosis. In this study, we performed a detailed molecular characterization of the recurrent translocation t(3;17)(q26;q22) in 13 hematologic malignancies. The EVI1 gene locus was rearranged in all 13 patients and was associated with EVI1 overexpression. In 9 out of 13 patients, the 17q breakpoints clustered in a 250 kb region on band 17q22 encompassing the MSI2 (musashi homologue 2) gene. Expression analyses failed to demonstrate ectopic MSI2 expression or the presence of an MSI2/EVI1 fusion gene. In conclusion, we show for the first time that the t(3;17) is indeed a recurrent chromosomal aberration in myeloid malignancies. In keeping with findings in other recurrent 3q26 rearrangements, overexpression of the EVI1 gene appears to be the major contributor to leukemogenesis in patients with a t(3;17).     

Clinical and hematologic characteristics in acute leukemia with 11q23 translocations

We studied the clinical, morphological, and immunologic characteristics of 11 patients with 11q translocation-associated acute leukemia. There were three patients with t(9;11)(p22;q23), one with a variant of the t(9;11), three with t(11;19)(q23;p13), two with t(1;11)(p32;q23), one with t(10;11)(p15;q22or23), and one with t(11;17) (q23;q25). The breakpoints in chromosome 11 clustered in band q23. The morphological feature was FAB-M5 in two patients, FAB-M2 in one, FAB-L1 in six, and lymphoblastic lymphoma in one. The remaining patient underwent morphological changes from FAB-L1 seen at the time of diagnosis to M5b at relapse. Immunologic marker studies in ten patients revealed that one had T cell type; another pre-B cell type; three CALLA- Ia- non-T, non-B type; two CAL-LA- Ia+ non-T, non-B type; two monocytic type (positive Fc-receptor); and the remaining one underwent phenotypic changes from CALLA+ Ia+ non-T, non-B type to monocytic type. The patients were usually young; five were under 1 year and two were 9 and 13 years. Hyperleukocytosis was observed in eight of the ten patients with acute leukemia, and two of the eight died of intracranial hemorrhage within two days of admission, associated with disseminated intravascular coagulation. These findings indicate that leukemia with the 11q23 translocation share certain characteristics in common, irrespective of the recipient chromosome, even though the latter may have some influence on the morphological and immunologic phenotype. Our data provide a hypothesis that multipotent stem cells are involved in the genesis of the 11q translocation-associated leukemia.     

An interphase fluorescence in situ hybridisation assay for the detection of 3q26.2/EVI1 rearrangements in myeloid malignancies

Chromosome rearrangements involving band 3q26.2 are associated with myeloid malignancies, aberrant expression of the human ecotropic virus integration site-1 (EVI1) gene, an unfavourable prognosis and an aggressive clinical course. The 3q26.2 rearrangements are characteristically heterogeneous and typically difficult to detect in poor quality metaphases. To develop a dual-colour fluorescence in situ hybridisation (FISH) assay for the detection of 3q26.2/EVI1 aberrations, a series of 10 BAC clones corresponding to the EVI1 gene region were systematically evaluated and narrowed down to two probe sets; one probe set encompassed the EVI1 gene extending centromeric, while the second probe set covered the EVI1 gene and extends telomeric. Both probe sets were evaluated on 35 patient samples with cytogenetically defined 3q26.2 rearrangements collected at various treatment time points, the inv(3)(q21q26.2) Kasumi-4 cell line, and 10 known negative samples. The two-probe set strategy identified all samples, despite the vast breakpoint heterogeneity observed. In samples from acute myeloid leukaemia and myelodysplastic syndrome cases, the majority of inversion breakpoints were 3' to EVI1 whereas 3q26.2 translocation breakpoints frequently mapped 5' to EVI1. However, two 3q26.2 translocation samples had breakpoints 3' to EVI1. Most inv(3q) chronic myeloid leukaemia samples showed breakpoints within the EVI1 gene. This study demonstrated that, despite the extensive breakpoint heterogeneity observed with 3q26.2 aberrations, this FISH strategy is effective for the detection of 3q26.2 abnormalities in myeloid malignancies.     

Lenalidomide in lower-risk myelodysplastic syndromes with karyotypes other than deletion 5q and refractory to erythropoiesis-stimulating agents

Lenalidomide (LEN) has been shown to yield red blood cell (RBC) transfusion independence in about 25% of lower risk myelodysplastic syndromes (MDS) without del(5q), but its efficacy in patients clearly refractory to erythropoiesis-stimulating agents (ESA) is not known. We report on 31 consecutive lower-risk non-del(5q) MDS patients with anaemia refractory to ESA and treated with LEN in a compassionate programme, 20 of whom also received an ESA. An erythroid response was obtained in 15 patients (48%), including 10 of the 27 (37%) previously transfusion-dependent (RBC-TD) patients, who became transfusion-independent (RBC-TI). Nine of the responders relapsed, whereas 6 (40%) were still responding and transfusion-free after 11(+)-31(+) months. Median response duration was 24 months. The erythroid response rate was lower in refractory cytopenia with multilineage dysplasia (27% vs. 60%) and tended to be higher in patients treated with LEN + ESA (55% vs. 36%). Response duration was significantly longer in responders who obtained RBC-TI and in patients treated with LEN after primary resistance to ESA. The main toxicity of LEN was cytopenias. We confirm that, in a patient population of lower risk MDS without del 5q clearly resistant to ESA, LEN is an interesting second line therapeutic option. Its combination with ESAs in this context warrants prospective studies.     

The role of lenalidomide in the treatment of patients with chromosome 5q deletion and other myelodysplastic syndromes

PURPOSE OF REVIEW: The aim of this article is to discuss the relevant pathobiologic effects of lenalidomide and the most recent clinical evidence to support its use in patients with myelodysplastic syndrome. RECENT FINDINGS: Lenalidomide is an immunomodulatory agent with biological activity in several hematologic malignancies, including myelodysplastic syndrome. The precise mechanism yielding benefit in patients with myelodysplastic syndrome and 5q- syndrome is not clear, but various molecular and pathogenic targets have been identified. Enhancement of cellular immunity through T-cell and NK-cell activation and suppression of inflammatory cytokines and pro-angiogenic peptides upon lenalidomide treatment has been demonstrated in in-vitro models of myelodysplastic syndrome. Furthermore, lenalidomide induces a direct cytotoxic effect against 5q- clones in leukemia cell lines and enhances ligand-induced erythropoietin receptor signaling in erythroid progenitors. Clinical trials with lenalidomide in myelodysplastic syndrome have supported the in-vitro evidence of karyotype-dependent activity by demonstration of a high frequency of cytogenetic and pathologic responses in patients with myelodysplastic syndrome and deletion of chromosome 5q. Lenalidomide was approved for the treatment of transfusion-dependent patients with low to intermediate risk myelodysplastic syndrome and chromosome 5q deletion. SUMMARY: Lenalidomide is an active immunomodulatory agent for the treatment of myelodysplastic syndrome with encouraging erythropoetic and cytogenetic remitting activity that is karyotype dependent.     

Molecular pathogenesis of myelodysplastic syndromes with deletion 5q

The molecular pathogenesis of deletion 5q (del(5q)) myelodysplastic syndrome (MDS) has recently been realized as a result of major advances in our understanding of the mechanisms responsible for clinical phenotype. Identification of commonly deleted genes such as RPS14, miRNA‐145, HSPA9, CD78, and CSNK1a1 have elucidated the precise biological changes responsible for the anemia, leukopenia, and thrombocytosis that characterizes del(5q) MDS and highlighted the importance of allelic haploinsufficiency in the hematological phenotype. Recent elegant investigations have also identified a critical role of innate immune signaling in del(5q) pathogenesis. TP53 and Wnt/β‐catenin pathways have also been found to be involved in clonal expansion and progression of the disease as well as resistance and poor outcomes to available therapy. Understanding the molecular pathogenesis of the disease has provided a critical foundation in identifying the biological targets of lenalidomide in del(5q) MDS, which has led to the development of novel therapeutic agents in hematologic malignancies as well as potential alternative targets to exploit in patients who have failed lenalidomide treatment.     

胰岛素样生长因子-I受体在MDS患者骨髓细胞中的表达和意义

目的:探讨骨髓增生异常综合征(MDS)患者骨髓造血细胞胰岛素样生长因子-I受体(IGF-IR)基因的定量表达情况.方法:用实时定量PCR(real time RT-PCR)方法检测胰岛素样生长因子-I受体mRNA的表达量.结果:IGF-IR基因表达量在MDS各亚组和正常对照存在不同:RAEB组(1.31E-04)和CMML组患者(1.99E-04)均明显高于正常对照(1.45E-05,P值分别<0.05和0.01),而与正常对照相比,RA组患者IGF-IR基因表达量(5.75E-06)未显示统计学差异.结论:IGF-IR 基因在高危组MDS(RAEB/CMML)患者造血细胞存在过度表达,而未见于低危组(RA)患者,提示IGF-IR可能参与MDS疾病的发生、发展.