Angiogenesis in acute myeloid leukemia and myelodysplastic syndrome

Increased angiogenesis is important in the pathophysiology of solid tumors. Recent studies show that angiogenesis and angiogenic factors play an important role in hematological malignancies. Both acute myeloid leukemia (AML) and myelodysplastic syndrome (MDS) are associated with a substantial increase in vascularity in the bone marrow as well as increased levels of various angiogenic factors including vascular endothelial growth factor (VEGF), basic fibroblast growth factor, angiogenin, angiopoietin-1, platelet-derived growth factor, hepatocyte growth factor, epidermal growth factor, tumor necrosis factor-alpha, and transforming growth factor-alpha and transforming growth factor-beta. Most of these angiogenic factors appear to be secreted by the neoplastic hematopoietic cells and appear to promote the growth and proliferation of the leukemic cells in an autocrine fashion. More importantly, angiogenic factors play a role in the clinical behavior and outcome of both AML and MDS. Despite significant overlap between MDS and AML in many aspects, higher levels of cellular VEGF and lower levels KDR are seen in MDS than in AML. Antiangiogenic therapy may play a role in AML and MDS and some differences in response may exist between MDS and AML.     

Clinicopathological aspects of therapy-related acute myeloid leukemia and myelodysplastic syndrome

Therapy-related myeloid neoplasm (t-MN) is a rare but devastating consequence of chemotherapy and/or radiotherapy used for the treatment of solid cancers and various hematologic malignancies. Our current understanding of the etiology is that hematopoietic clones that are contemporaneous with the primary cancer and resistant to the cytotoxic exposure have the potential to undergo selective expansion and transformation to t-MN. Consequently, a large proportion of cases are associated with adverse risk factors, resulting in limited effective treatment options. Despite the emergence of some therapies with promising activity in t-MN, most effects are short-lived and allogeneic stem cell transplantation remains the only curative option for eligible patients. This review summarizes the current literature on t-AML and t-MDS, with the aim of providing practical recommendations on the clinical evaluation and management of these conditions.     

Autologous stem cell transplantation for therapy-related acute myeloid leukemia and myelodysplastic syndrome

We report the results of 65 patients with treatment-related myelodysplastic syndrome (MDS)/acute myelogenous leukemia (AML) who were transplanted from an autograft and reported to the EBMT. The median age was 39 years (range, 3-69), and stem cell source was bone marrow (n = 31), or peripheral blood progenitor cells (n = 30), or the combination of both (n = 4). The primary disease was solid tumors (n = 37), Hodgkin's disease (n = 13), non-Hodgkin's lymphoma (n = 10), acute lymphoblastic leukemia (n = 2) or myeloproliferative syndromes (n = 3). The types of MDS were as follows: RAEB (n = 1; 2%), RAEB-t (n = 3; 5%), or AML (n = 56; 87%). The median time between diagnosis and transplantation was 5 months (range, 3-86). The Kaplan-Meier estimates of the probability of 3-year overall and disease-free survival were 35% (95% CI: 21-49%) and 32% (95% CI: 18-45%), respectively. The median leukocyte engraftment was faster after transplantation with peripheral blood stem cells than with bone marrow: 12 (range, 9-26) vs 29 (range, 11-67) days (P<0.001). The cumulative incidence of relapse was 58% (95% CI: 44-72%) and of treatment-related mortality 12% (95% CI: 6-38%). Lower relapse rate was seen in patients transplanted in first complete remission (CR1 vs non-CR1: 3 years: 48 vs 89%; P = 0.05). Furthermore, age beyond 40 years resulted in a higher treatment-related mortality (47 vs 7%; P = 0.01). In a multivariate analysis, transplantation in CR1 age as well as their interaction influenced overall survival significantly. Autologous transplantation may cure a substantial number of patients with treatment-related MDS/AML, especially if they are in CR1 and of younger age.     

Simultaneous expression of lymphoid and myeloid phenotypes in acute leukemia arising from myelodysplastic syndrome

A 57-year-old female developed myelodysplastic syndrome (MDS) that terminated as a biphenotypic leukemia after exposure to chemoradiotherapy. Double staining of blast cells, using monoclonal antibodies specific for myeloid and lymphoid lineage, demonstrated that one-third of the leukemic cells simultaneously expressed the E rosette-associated antigen (OKT11) and myeloid-associated antigen (MY7). This finding suggests the possibility that some cases of MDS are clonal disorders that arise in a pluripotent stem cell that can also differentiate to T cell lineage.     

急性髓系白血病及骨髓增生异常综合征患者血管内皮生长因子表达的研究

目的了解血管内皮生长因子(VEGF)在急性髓系白血病(AML)和骨髓增生异常综合征(MDS)中血管新生的作用。方法用ELISA法检测20例AML及24例MDS患者骨髓单个核细胞培养上清VEGF的表达。结果AML患者骨髓细胞VEGF的水平(267.35～412.30ng/L)高于对照组(128.17ng/L),化疗后完全缓解组的VEGF水平明显下降(P<0.05)化疗后未缓解组的VEGF水平与治疗前比较无显著下降(P>0.05)。MDS高危型(RAEB或RAEBt)中VEGF水平与低危型(RA或RAS)及对照组相比均明显升高(P<0.05),其中RAEBt与AML患者相比差异无显著性(P>0.05)。结论AML及高危型MDS患者骨髓中存在血管新生,VEGF在AML及MDS发病中起着重要作用,VEGF的表达与MDS病程进展有关。     

Frequent genomic abnormalities in acute myeloid leukemia/myelodysplastic syndrome with normal karyotype

Background

Acute myeloid leukemia is a clonal hematopoietic malignant disease; about 45–50% of cases do not have detectable chromosomal abnormalities. Here, we identified hidden genomic alterations and novel disease-related regions in normal karyotype acute myeloid leukemia/myelodysplastic syndrome samples.

Design and Methods

Thirty-eight normal karyotype acute myeloid leukemia/myelodysplastic syndrome samples were analyzed with high-density single-nucleotide polymorphism microarray using a new algorithm: allele-specific copy-number analysis using anonymous references (AsCNAR). Expression of mRNA in these samples was determined by mRNA microarray analysis.

Results

Eighteen samples (49%) showed either one or more genomic abnormalities including duplication, deletion and copy-number neutral loss of heterozygosity. Importantly, 12 patients (32%) had copy-number neutral loss of heterozygosity, causing duplication of either mutant FLT3 (2 cases), JAK2 (1 case) or AML1/RUNX1 (1 case); and each had loss of the normal allele. Nine patients (24%) had small copy-number changes (< 10 Mb) including deletions of NF1, ETV6/TEL, CDKN2A and CDKN2B. Interestingly, mRNA microarray analysis showed a relationship between chromosomal changes and mRNA expression levels: loss or gain of chromosomes led, respectively, to either a decrease or increase of mRNA expression of genes in the region.

Conclusions

This study suggests that at least one half of cases of normal karyotype acute myeloid leukemia/myelodysplastic syndrome have readily identifiable genomic abnormalities, as found by our analysis; the high frequency of copy-number neutral loss of heterozygosity is especially notable.     

Intensive treatment strategies in patients with high-risk myelodysplastic syndrome and secondary acute myeloid leukemia

Stem cell transplantation may lead to prolonged disease-free survival in young patients with high-risk myelodysplastic syndrome (MDS) and secondary acute myeloid leukemia. About one-third of patients transplanted with an HLA-identical family donor will experience long-term disease-free survival. Outcome appears to be better for younger patients, patients with less advanced stages of MDS and treatment early in the course of the disease. The results of transplantation using partially matched family donors and phenotypically matched voluntary unrelated donors are still unsatisfactory, mainly due to significantly higher transplantation related mortality rate. For patients lacking a suitable sibling donor autologous stem cell transplantation may constitute an alternative. The presence of sufficient residual polyclonal stem cells and achieving a complete remission after chemotherapy forms a prerequisite for a successful transplantation. Further development of accurate prognostic classification systems will allow a risk-adapted strategy for an individual patient.     

Risk factors for evolution of acquired aplastic anemia into myelodysplastic syndrome and acute myeloid leukemia after immunosuppressive therapy in children

Long-term survivors of acquired aplastic anemia (AA) have an increased risk of developing myelodysplastic syndrome (MDS) and acute myeloid leukemia (AML) after immunosuppressive therapy (IST). It is uncertain whether the increased survival time simply discloses the natural history of AA as a premalignant disease or whether secondary disease is related to the therapy itself. Between November 1992 and September 1997, 113 AA children with normal cytogenetics at diagnosis were treated with IST using antithymocyte globulin, cyclosporin, and danazol with or without granulocyte colony-stimulating factor (G-CSF). We assessed risk factors for developing MDS/AML by Cox proportional hazards models. Twelve of 113 patients developed MDS between 9 and 81 months following the time of diagnosis, giving a cumulative incidence of 13.7 +/- 3.9%. The following cytogenetic abnormalities were observed at the time of diagnosis of MDS: monosomy 7 (6 patients), monosomy7/trisomy21 (1 patient), trisomy 11 (1 patient), del (11) (9?:14) (1 patient), add (9q) (1 patient), add 7 (q 32) (1 patient), and trisomy 9 (1 patient). The number of days of G-CSF therapy and nonresponse to therapy at 6 months were statistically significant risk factors by multivariate analysis. The present study suggests a close relationship between long-term use of G-CSF and secondary MDS in nonresponders to IST.     

Abrupt evolution of Philadelphia chromosome‐positive acute myeloid leukemia in myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a clonal disorder arising from an alteration in multipotent stem cells, which lose the ability of normal proliferation and differentiation. Disease progression occurs in approximately 30% MDS cases. Specific chromosomal alterations seem responsible for each step in the evolution of acute myeloid leukemia (AML). Multiple genetic aberrations occur during the clonal evolution of MDS; however, few studies report the presence of the Philadelphia (Ph) chromosome. We report a rare case of Ph‐positive AML, which evolved during the course of low‐risk MDS. The patient, a 76‐year‐old man with mild leukocytopenia, was diagnosed with MDS, refractory neutropenia (RN). After 1.5 yr, his peripheral blood and bone marrow were suddenly occupied by immature basophils and myeloblasts, indicating the onset of AML. A bone marrow smear showed multilineage dysplasia, consistent with MDS evolution. Chromosomal analysis showed an additional t(9;22)(q34;q11) translocation. Because progression occurred concurrently with emergence of the Ph chromosome, we diagnosed this case as Ph‐positive AML with basophilia arising from the clonal evolution of MDS. The patient was initially treated with nilotinib. A hematological response was soon achieved with disappearance of the Ph chromosome in the bone marrow. Emergence of Ph‐positive AML in the course of low‐risk MDS has rarely been reported. We report this case as a rare clinical course of MDS.     

Prognostic implications of CD14 positivity in acute myeloid leukemia arising from myelodysplastic syndrome

Secondary acute myeloid leukemia (s-AML) arising from myelodysplastic syndrome (MDS) shows different clinical features from de novo AML. We assessed the prognostic significance of immunophenotypic markers in patients with s-AML arising from MDS. Sixty-five adults diagnosed with AML arising from MDS between 1996 and 2010 were retrospectively analyzed. Immunophenotyping was performed for markers including CD3, CD7, CD10, CD13, CD14, CD19, CD33, CD34, CD41, CD45, CD56, CD65, CD117, HLA-DR, and TdT. Of these immunophenotypic markers, only CD14 positivity was significantly associated with lower complete remission rate (P = 0.034) and significantly shorter overall survival (OS, P < 0.001) and event-free survival (EFS, P < 0.001) on univariate analysis. On multivariate analysis, these differences remained significant in terms of OS [hazard ratio (HR) 4.49; P < 0.001] and EFS (HR 4.06; P < 0.001). Other significant prognostic variables included age ≥60 years [shorter OS (P = 0.003) and EFS (P = 0.020)], higher WBC count (>60,000/μL) [shorter OS (P < 0.001) and EFS (P = 0.001)], and poor cytogenetic risk group [shorter OS (P = 0.005)]. CD14 expression on leukemic blasts is an independent prognostic factor for survival outcomes in patients with AML arising from MDS.     

Therapy-related patterns of cytogenetic abnormalities in acute myeloid leukemia and myelodysplastic syndrome post polycythemia vera

A minor fraction of patients with polycythemia vera (PV) develop a terminal acute myeloid leukemia (AML) or myelodysplastic syndrome (MDS). Analysis of the cytogenetic abnormalities during AML or MDS may help in understanding if this development is part of the natural course of the disease or induced by myelosuppressive therapy. Thirty-six cases with AML or MDS post PV, collected in a single Swedish institution during a 33-year period, are described with special regard to time to development of AML or MDS, therapy given during active PV, and cytogenetic findings during AML or MDS. A further 118 cases of AML or MDS post PV, in whom type of therapy during active PV and cytogenetic findings during AML or MDS were reported, were collected from the literature. AML or MDS developed in our own series after 1–30 years with a fairly constant rate (two cases per year). The most frequent cytogenetic abnormalities were +1q, −5, 5q−, −7, 7q−, +8, +9, 11q−, 13q−, and 20q−. When patients in the total material (n = 154) were divided with regard to treatment during active PV, marked differences were observed. The highest frequency of abnormalities was found in patients given multiple lines of therapy (n = 61), dominating features being −5/5q− in 28 patients (46%), −7/7q− in 19 patients (31%), numerous translocations in 24 patients (39%), and unidentified markers in 22 patients (36%). Half of the patients treated with hydroxyurea alone showed a −5 or 5q− abnormality. In patients treated with phlebotomy alone, +8 and +9 were the most frequent findings. The type of therapy given during active PV influences the type of chromosome abnormalities present during terminal AML or MDS and can also be instrumental in the development of leukemia.     

Arsenic disulfide-triggered apoptosis and erythroid differentiation in myelodysplastic syndrome and acute myeloid leukemia cell lines

Objectives

Effects of arsenic disulfide (As₂S₂) were investigated by focusing on growth inhibition, apoptosis induction, and erythroid differentiation in MDS-L, F-36p and HL-60 cells, derived from myelodysplastic syndrome (MDS), MDS/acute myeloid leukemia (AML), and de novo AML, respectively.

Methods

Cell viability was determined by MTT assay. Apoptosis induction was analyzed using Annexin V/propidium iodide staining. Erythroid differentiation was assessed by the expression level of CD235a, a marker for detection of the erythroid cell lineage. The activation of p38 MAPK and the expression profile of apoptosis-related proteins Bcl-2 and Bid were analyzed using western blot.

Results

As₂S₂ inhibited cell growth of these cell lines. Of note, the IC₅₀ value of As₂S₂ in MDS-L cells was comparable to that in F-36p cells, and was half of that in HL-60 cells. A dose-dependent decrease in cell viability and concomitant increase in the percentage of apoptotic cells were observed in F-36p cells treated with 8 and 16 µM As₂S₂ for 72 hours. However, similar phenomena were only observed in HL-60 cells when treated with as high as 16 µM As₂S₂. Furthermore, As₂S₂ exerted more potent erythroid differentiation-inducing activity on F-36p cells than HL-60 cells. Interestingly, negative correlation between p38 MAPK signaling pathway and As₂S₂-induced erythroid differentiation was observed in HL-60 cells. Treatment with relatively high concentration of As₂S₂ resulted in the downregulation of Bcl-2 and Bid proteins in HL-60 cells.

Discussion

These results suggest that compared to AML cell line, MDS and MDS/AML cell lines are more sensitive to not only the erythroid differentiation-inducing activity of As₂S₂, but also its cytotoxicity associated with apoptosis induction. These findings further provide novel insight into As₂S₂ action toward its use for clinical application in patients with hematological disorders.     

Defective DNA mismatch repair in acute myeloid leukemia/myelodysplastic syndrome after organ transplantation

Immunosuppression after organ transplantation is an acknowledged risk factor for skin cancer and lymphoma. We examined whether there was also an excess of leukemia in patients after transplantation and whether this might be related to a particular immunosuppressive treatment. Data from more than 170 000 patients indicated that organ transplantation is associated with a significantly increased risk for acute myeloid leukemia (AML). AML was more frequent after heart transplantation and lung transplantation than after kidney transplantation and was associated with immunosuppression by azathioprine, a thiopurine prodrug. Cellular resistance to thiopurines is associated with DNA mismatch repair (MMR) deficiency. We demonstrate that thiopurine treatment of human cells in vitro selects variants with defective MMR. Consistent with a similar selection in patient bone marrow, in 7 of 7 patients, transplant-related AML/myelodysplastic syndrome (MDS) exhibited the microsatellite instability (MSI) that is diagnostic for defective MMR. Because MSI occurs infrequently in de novo AML, we conclude that the selective proliferation of MMR-defective, azathioprine-resistant myeloid cells may contribute significantly to the development of AML/MDS in patients who have received organ transplants. Identifying azathioprine as a risk factor for AML/MDS suggests that discontinuing the use of azathioprine as an immunosuppressant might reduce the incidence of posttransplantation AML/MDS.