Severe thrombocytopenia is a major risk factor for haemorrhage, and yet platelet function and bleeding risk at low platelet counts are poorly understood because of limitations of platelet function testing at very low platelet counts.
To examine and compare platelet function in severely thrombocytopenic patients with acute myeloid leukaemia (AML) or myelodysplasia (MDS) to patients with immune thrombocytopenia (ITP).
Whole blood flow cytometric measurement of platelet activation and platelet reactivity to agonists was correlated with the immature platelet fraction (IPF) and bleeding symptoms.
Compared with patients with ITP, patients with AML/MDS had smaller platelets, lower IPF, and substantially lower platelet surface expression of activated GPIIb/IIIa and GPIb both with and without addition of ex vivo ADP or TRAP. In both ITP and AML/MDS, increased platelet surface GPIb on circulating platelets and expression of activated GPIIb/IIIa and GPIb on ex vivo activated platelets correlated with a higher IPF. Whereas platelet reactivity was higher for AML/MDS patients with bleeding than those with no bleeding, platelet reactivity was lower for ITP patients with bleeding than those with no bleeding.
AML/MDS patients have lower in vivo platelet activation and ex vivo platelet reactivity than patients with ITP. The proportion of newly-produced platelets correlates with the expression of platelet surface markers of activation. These differences might contribute to differences in bleeding tendency between AML/MDS and ITP. This study is the first to define differences in platelet function between AML/MDS patients and ITP patients with equivalent degrees of thrombocytopenia.
Autoimmunity; bleeding; flow cytometry; haemorrhage; thrombocytopenia; thrombopoiesis
RUNX1 is generally considered a tumor suppressor in myeloid neoplasms. Inactivating RUNX1 mutations have frequently been found in patients with myelodysplastic syndrome (MDS) and cytogenetically normal acute myeloid leukemia (AML). However, no somatic RUNX1 alteration was found in AMLs with leukemogenic fusion proteins, such as core-binding factor (CBF) leukemia and MLL fusion leukemia, raising the possibility that RUNX1 could actually promote the growth of these leukemia cells. Using normal human cord blood cells and those expressing leukemogenic fusion proteins, we discovered a dual role of RUNX1 in myeloid leukemogenesis. RUNX1 overexpression inhibited the growth of normal cord blood cells by inducing myeloid differentiation, whereas a certain level of RUNX1 activity was required for the growth of AML1-ETO and MLL-AF9 cells. Using a mouse genetic model, we also showed that the combined loss of Runx1/Cbfb inhibited leukemia development induced by MLL-AF9. RUNX2 could compensate for the loss of RUNX1. The survival effect of RUNX1 was mediated by BCL2 in MLL fusion leukemia. Our study unveiled an unexpected prosurvival role for RUNX1 in myeloid leukemogenesis. Inhibiting RUNX1 activity rather than enhancing it could be a promising therapeutic strategy for AMLs with leukemogenic fusion proteins.
RUNX1/AML1 is required for definitive hematopoiesis and is frequently targeted by chromosomal translocation in acute myeloid leukemias (AML). The t(8;21) related AML1-ETO fusion protein blocks differentiation of myeloid progenitors. Here, we show by immunofluorescence microscopy that during interphase, endogenous AML1-ETO localizes to nuclear microenvironments distinct from those containing native RUNX1/AML1 protein. At mitosis, we clearly detect binding of AML1-ETO to nucleolar organizing regions (NORs) in AML derived Kasumi-1 cells and binding of RUNX1/AML1 to NORs in Jurkat cells. Both RUNX1/AML1 and AML1-ETO occupy ribosomal DNA repeats during interphase, as well as interact with the endogenous RNA Pol I transcription factor UBF-1. Promoter cytosine methylation analysis indicates that RUNX1/AML1 binds to rDNA repeats that are more highly CpG methylated than those bound by AML1-ETO. Down-regulation by RNA interference reveals that RUNX1/AML1 negatively regulates rDNA transcription, while AML1-ETO is a positive regulator in Kasumi-1 cells. Taken together, our findings identify a novel role for the leukemia-related AML1-ETO protein in epigenetic control of cell growth through upregulation of RNA Pol I-mediated ribosomal gene transcription, consistent with the hyper-proliferative phenotype of myeloid cells in AML patients.
acute myelogenous leukemia; Runx1; ribosomal DNA transcription; RNA polymerase I; UBF1; nucleolar organizing region
The transition of patients with ≥20% <30% bone marrow (BM) blast from the FAB category of myelodysplasia to the family of acute myeloid leukemia (AML) according to the recent WHO classification has not resolved the argument as to whether the natural history and responsiveness to therapy of these diseases is comparable to that of AML with > 30% BM blast. These controversies are even more manifest when it comes to elderly patients in whom concern for intensive chemotherapy (IC) related toxicity is the critical determinant for the therapeutic choice. In fact, due to concerns of treatment-related morbidity and mortality associated with delivery of IC, approximately only 30% of all patients ≥65 years are considered eligible for this approach. Therefore, a great deal of attention has been dedicated to alternative agents such as hypomethylators (azacitidine and decitabine). Actually, these agents have shown efficacy with reduced toxicity when administered to elderly patients with 20–30% BM blasts and not eligible for IC. In the present review, we will discuss the clinical results achieved in the treatment of elderly patients with 20%–30% BM blasts AML using intensive chemotherapy (IC) or hypomethylating agents. Overall, our survey of the literature suggests that only controlled, randomized, clinical trials will answer the question as to whether hypomethylating agents has the potential to substitute for IC even in elderly patients with an optimal functional status.
Therapy-related myelodysplasia or acute myelogenous leukemia (t-MDS/AML) is a lethal complication of autologous hematopoietic stem-cell transplantation (aHCT) for Hodgkin's lymphoma (HL) and non-Hodgkin's lymphoma (NHL). Here, we investigated the hypothesis that accelerated telomere shortening after aHCT could contribute to the development of t-MDS/AML.
Patients and Methods
A prospective longitudinal cohort was constructed to investigate the sequence of cellular and molecular abnormalities leading to development of t-MDS/AML after aHCT for HL/NHL. This cohort formed the sampling frame for a nested case-control study to compare changes in telomere length in serial blood samples from patients who developed t-MDS/AML with matched controls who did not develop t-MDS/AML.
An initial increase in telomere length at day 100 after aHCT was followed by an accelerated telomere shortening in t-MDS/AML patients when compared with controls. These telomere alterations preceded the onset of t-MDS and were independent of other known risk factors associated with development of t-MDS/AML on multivariate analysis. Additionally, we observed reduced generation of committed progenitors in patients who developed t-MDS/AML, indicating that these telomere alterations were associated with reduced regenerative capacity of hematopoietic stem cells.
The development of t-MDS/AML after aHCT is associated with and preceded by markedly altered telomere dynamics in hematopoietic cells. Accelerated telomere loss in patients developing t-MDS/AML may reflect increased clonal proliferation and/or altered telomere regulation in premalignant cells. Genetic instability associated with shortened telomeres may contribute to leukemic transformation in t-MDS/AML.
The rare but recurrent RUNX1-USP42 fusion gene is the result of a t(7;21)(p22;q22) chromosomal translocation and has been described in 6 cases of acute myeloid leukemia (AML) and one case of refractory anemia with excess of blast. In the present study, we present the molecular genetic analysis and the clinical features of a t(7;21)(p22;q22)-positive AML case. PCR amplified two RUNX1-USP42 cDNA fragments but no reciprocal USP42-RUNX1 fragment indicating that the RUNX1-USP42 is the leukemogenic fusion gene. Sequencing of the two amplified fragments showed that exon 6 or exon 7 of RUNX1 (accession number NM_001754 version 3) was fused to exon 3 of USP42 (accession number NM_032172 version 2). The predicted RUNX1-USP42 fusion protein would contain the Runt homology domain (RHD), which is responsible for heterodimerization with CBFB and for DNA binding, and the catalytic UCH (ubiquitin carboxyl terminal hydroxylase) domain of the USP42 protein. The bone marrow cells in the present case also had a 5q deletion, and it was revealed that 5 out of the 8 reported cases (including the present case) with t(7;21)(p22;q22)/RUNX1-USP42 also had cytogenetic abnormalities of 5q. The fact that t(7;21) and 5q- occur together much more often than chance would allow seems to be unquestionable, although the pathogenetic connection between the two aberrations remains unknown.
acute myeloid leukemia; cytogenetic; t(7;21)(p22;q22); 5q aberration; RUNX1; USP42; fusion gene
Acute promyelocytic leukemia (APL) is a relatively common form of acute myeloid leukemia (AML) that has an excellent prognosis. In contrast, secondary acute myeloid leukemias, including therapy-related AML and AML with myelodysplasia-related changes, have a relatively poor prognosis. We identified 9 cases of APL at our institution in which there was a history of chemotherapy, radiotherapy, chronic immunosuppression, or antecedent myelodysplastic syndrome. The clinical and pathologic findings in these cases of secondary APL were compared with the clinical and pathologic findings in cases of de novo APL. We found that secondary and de novo APL had abnormal promyelocytes with similar morphologic and immunophenotypic features, comparable cytogenetic findings, comparable rates of FMS-like tyrosine kinase mutations, and similar rates of recurrent disease and death. These data suggest that secondary APL is similar to de novo APL and, thus, should be considered distinct from other secondary acute myeloid neoplasms.
Acute promyelocytic leukemia; APL; Therapy-related acute myeloid leukemia; Therapy-related myeloid neoplasm; Acute myeloid leukemia with myelodysplasia-related changes; Flow cytometry
Severe congenital neutropenia (SCN) is associated with a marked propensity to develop myelodysplasia (MDS) or acute myeloid leukemia (AML). Truncation mutations of CSF3R, encoding the G-CSF receptor (G-CSFR), are associated with the development of MDS/AML in SCN. However, a causal relationship between CSF3R mutations and leukemic transformation has not been established. Herein, we show that truncated G-CSFR cooperates with the PML-RARα oncogene to induce AML in mice. Expression of truncated G-CSFR significantly shortens the latency of AML in a G-CSF dependent fashion, and it is associated with a distinct AML presentation characterized by higher blast counts and more severe myelosuppression. Basal and G-CSF-induced STAT3, STAT5, and Erk1/2 phosphorylation were highly variable but similar in leukemic blasts expressing wild type and truncated G-CSFR. These data provide new evidence suggesting a causative role for CSF3R mutations in human AML.
Acute myeloid leukemia; neutropenia; severe congenital neutropenia; myelodysplastic syndrome; granulocyte-colony stimulating factor (G-CSF); STAT3; STAT5
Therapy-related myelodysplasia or acute myeloid leukemia (t-MDS/AML) is a major complication of cancer treatment. We compared gene expression in CD34+ cells from patients who developed t-MDS/AML after autologous hematopoietic cell transplantation (aHCT) for lymphoma with controls who did not develop t-MDS/AML. We observed altered gene expression related to mitochondrial function, metabolism, and hematopoietic regulation in pre-aHCT samples from patients who subsequently developed t-MDS/AML. Progression to overt t-MDS/AML was associated with additional alterations in cell-cycle regulatory genes. An optimal 38-gene PBSC classifier accurately distinguished patients who did or did not develop t-MDS/AML in an independent group of patients. We conclude that genetic programs associated with t-MDS/AML are perturbed long before disease onset, and accurately identify patients at risk for this complication.
Granulocytic sarcoma (GS) is a rare extramedullary solid tumor defined as an accumulation of myeloblasts or immature myeloid cells. It can cooccur with or precede the acute myeloid leukemia (AML) as well as following treated AML. The incidence of GS in AML patients is 3–8% but it significantly rises in M2 FAB subtype AML. This variety of AML harbors t(8;21) in up to 20–25% of cases (especially in children and black ones of African origin) and, at a molecular level, it is characterized by the generation of a fusion gene known as RUNX1-RUNX1T1. Approximately 10% of M2 AML patients will develop GS, as a consequence, the t(8;21) and the relative transcript represent the most common cytogenetic and molecular abnormalities in GS. FLT3-ITD mutation was rarely described in AML patients presenting with GS. FLT3 ITD is generally strongly associated with poor prognosis in AML, and is rarely reported in patients with t(8;21). GS presentation is extremely variable depending on organs involved; in general, cranial bones and sinus are very rarely affected sites. We report a rare case of GS occurring as a recurrence of a previously treated t(8;21), FLT3-ITD positive AML, involving mastoid bones and paravertebral tissues.
We sought to improve outcome of childhood acute myeloid leukemia (AML) by applying risk-directed therapy based on the genetic abnormalities of the leukemic cells and measurements of minimal residual disease (MRD) as determined by flow cytometry during treatment.
From October 13, 2002 to June 19, 2008, 232 patients with de novo AML (n=206), therapy- or myelodysplasia-related AML (n=12), or mixed-lineage leukemia (n=14) were enrolled at eight centers. Block, nonblinded randomization, stratified by cytogenetic or morphologic subtype, assigned patients to high-dose (18 g/m2, n=113) or low-dose (2 g/m2, n=117) cytarabine (A), given together with daunorubicin (D) and etoposide (E) (Induction I); achievement of MRD negative status was the primary endpoint. Induction II consisted of ADE with or without gemtuzumab ozogamicin (GO); consolidation therapy included three additional courses of chemotherapy or hematopoietic stem cell transplantation (HSCT). Levels of MRD were used to allocate GO and determine the timing of Induction II; both MRD and genetic abnormalities at diagnosis were used to determine final risk classification. Low-risk patients (n=68) received 5 courses of chemotherapy, whereas high-risk patients (n=79), as well as standard-risk patients (n=69) with matched sibling donors, were eligible for HSCT (performed in 48 high and 8 standard-risk patients). All randomized patients (n=230) were analyzed for the primary endpoint. The other analyses were limited to the 216 patients with AML, excluding mixed-lineage leukemia. This trial, closed to accrual, is registered with ClinicalTrial.gov, number NCT00136084.
The complete remission rates were 80% (173 of the 216) after Induction I and 94% (203 of 216) after Induction II. Induction failures included two toxic deaths and 10 cases of resistant leukemia. The introduction of high-dose cytarabine did not significantly lower the rate of MRD positivity after Induction I therapy (34% vs. 42%, P=0.17). The cumulative incidences of grade 3 or greater infection were 79.3% ± 4.0% and 75.5% ± 4.2% for patients treated on the high-dose or low-dose arms. The 3-year estimates (± SE) of event-free and overall survival were 63.0% ± 4.1% and 71.1% ± 3.8%, respectively. Achievement of MRD < 0.1% after Induction II identified a large group of patients (80%) with a cumulative incidence of relapse of only 17% ± 3%. Post-Induction I MRD ≥ 1% was the only independent adverse prognostic factor that was statistically significant (P < 0.05) for both event-free (HR, 2.41; CI 1.36–4.26; P=0.003) and overall survival (HR, 2.11; CI 1.09–4.11; P=0.028).
Our findings suggest that the use of targeted chemotherapy and HSCT, in the context of a comprehensive risk-stratification strategy based on genetic features and MRD findings, can improve the outcome of childhood AML.
t(8;21)(q22;q22) results in the AML1-ETO (A1E) fusion gene and is a common cytogenetic abnormality in acute myeloid leukemia (AML). Although insertions at the breakpoint region of the A1E fusion transcripts have been reported, additional structural alterations are largely uncharacterized. By RT-PCR amplifications and DNA sequencing, numerous in-frame and out-of-frame AML1b-ETO and AML1c-ETO transcripts were identified in 13 pediatric t(8;21) AMLs, likely resulting from alternate splicing, internal deletions, and/or breakpoint region insertions involving both the AML1 (RUNX1) and ETO regions. The in-frame A1E fusion transcript forms represented minor forms. These structure alterations were found in AML1c-ETO but not AML1b-ETO transcripts in 2 adult t(8;21) AMLs. Although no analogous alterations were detected in native AML1b transcripts, identical alterations in native ETO transcripts were identified. When transfected into HeLa cells, only AML1b, and not the in-frame A1E forms, transactivated the GM-CSF promoter. In co-transfection experiments, the effects of A1E proteins on GM-CSF transactivation by AML1b ranged from repressive to activating. Our results demonstrate a remarkable and unprecedented heterogeneity in A1E fusion transcripts in t(8;21) myeloblasts and suggest that synthesis of alternate A1E transcript and protein forms can significantly impact the regulation of AML1 responsive genes.
t(8;21); AML1-ETO; acute myeloid leukemia; fusion transcripts
Despite progress in understanding the biology of acute myeloid leukemia (AML), and despite advances in treatment, the majority of patients with AML die from the disease. The observation that Vitamin D can induce AML blast cells in vitro to differentiate along the monocytic lineage was made 30 years ago; however, it remains to translate this into a clinically meaningful strategy. This is a review of published clinical experience regarding the use of Vitamin D and its analogs, either alone or in combination with other agents, to treat AML. In many of these reports, investigators included patients with myelodysplasia (MDS) as well as AML patients in their treatment cohorts; therefore reports of Vitamin D and its analogs in treating MDS are included. This review documents heterogeneity in selection criteria for patients treated in these studies, the spectrum of Vitamin D analogs used in various studies, and the differing dosing strategies employed by investigators. Despite examples of occasional clinical efficacy, barriers remain to the successful application of Vitamin D in the treatment of MDS and AML. These include the lack of definition of a particularly sensitive target population, and the as yet unknown optimal choice of Vitamin D analog and dosing schedule.
RUNX1 is a transcription factor that regulates critical processes in many aspects of hematopoiesis. RUNX1 is also integral in defining the definitive hematopoietic stem cell. In addition, many hematological diseases like myelodysplastic syndrome and myeloproliferative neoplasms have been associated with mutations in RUNX1. Located on chromosomal 21, the RUNX1 gene is involved in many forms of chromosomal translocations in leukemia. t(8;21) is one of the most common chromosomal translocations found in acute myeloid leukemia (AML), where it results in a fusion protein between RUNX1 and ETO. The RUNX1-ETO fusion protein is found in approximately 12% of all AML patients. In this review, we detail the structural features, functions, and models used to study both RUNX1 and RUNX1-ETO in hematopoiesis over the past two decades.
RUNX1; AML1; CBFA2; RUNX1-ETO; AML1-ETO; RUNX1-RUNX1T1; Hematopoiesis; Hematopoietic Stem Cells; Leukemia; AML; Leukemogenesis; Mouse Models; Review
We reviewed and categorized 638 of 809 patients who were registered in the Japan Adult Leukemia Study Group acute myeloid leukemia (AML)-97 protocol using morphological means. Patients with the M3 subtype were excluded from the study group. According to the WHO classification, 171 patients (26.8%) had AML with recurrent genetic abnormalities, 133 (20.8%) had AML with multilineage dysplasia (MLD), 331 (51.9%) had AML not otherwise categorized, and 3 (0.5%) had acute leukemia of ambiguous lineage. The platelet count was higher and the rate of myeloperoxidase (MPO)-positive blasts was lower in AML with MLD than in the other WHO categories. The outcome was significantly better in patients with high (≥50%) than with low (<50%) ratios of MPO-positive blasts (P < 0.01). The 5-year survival rates for patients with favorable, intermediate, and adverse karyotypes were 63.4, 39.1, and 0.0%, respectively, and 35.5% for those with 11q23 abnormalities (P < 0.0001). Overall survival (OS) did not significantly differ between nine patients with t(9;11) and 23 with other 11q23 abnormalities (P = 0.22). Our results confirmed that the cytogenetic profile, MLD phenotype, and MPO-positivity of blasts are associated with survival in patients with AML, and showed that each category had the characteristics of the WHO classification such as incidence, clinical features, and OS.
AML; WHO classification; Myeloperoxidase; Multilineage dyplasia; 11q23 abnormalities
Trisomy 11 (+11) as an isolated abnormality is a rare event in patients with acute myeloid leukemia (AML) and is associated with poor prognosis. We describe the clinicopathologic features of 18 AML patients with isolated +11 and their mutation status of NPM1, FLT3, NRAS ,KRAS, and KIT. Fourteen patients had de novo AML and 4 patients had a history of myelodysplastic syndrome (MDS). Fifteen patients had a progressive clinical course with refractory or relapsed disease. The median overall survival was 5 months (range, 2 to 48 months). Only 1 patient achieved complete remission after undergoing stem cell transplantation. The bone marrow median blast count was 65% (range, 22 to 86) and 14 patients had blasts >50%. The most common type of AML was AML without maturation (7 patients) classified by the World Health Organization classification system, or M1 (10 patients) by the French-American-British (FAB) system. FLT3 mutations were detected in 3 of 15 (20%) cases tested. RAS mutation was present in 1 of 16 (6%) cases and there was no evidence of NPM1 of KIT mutations (each tested in 12 cases). Our findings confirm previous reports that isolated +11 is associated with a poor prognosis in patients with AML and tends to be associated with FAB-M1 morphologic features. No evidence of NPM1 or KIT mutations were identified.
Isolated trisomy 11; acute myeloid leukemia; gene mutations; prognosis
Dominant RUNX1 inhibition has been proposed as a common pathway for CBF-leukemia. CBFβ-SMMHC, a fusion protein in human acute myeloid leukemia (AML), dominantly inhibits RUNX1 largely through its RUNX1 high-affinity binding domain (HABD). However, the type I CBFβ-SMMHC fusion in AML patients lacks HABD. Here we report that the type I CBFβ-SMMHC protein binds RUNX1 inefficiently. Knock-in mice expressing CBFβ-SMMHC with a HABD deletion developed leukemia quickly, even though hematopoietic defects associated with Runx1-inhibition were partially rescued. A larger pool of leukemia initiating cells, increased MN1 expression, and retention of RUNX1 phosphorylation are potential mechanisms for accelerated leukemia development in these mice. Our data suggest that RUNX1 dominant inhibition may not be a critical step for leukemogenesis by CBFβ-SMMHC.
Fanconi’s anemia (FA) is an inherited bone marrow failure syndrome that carries a higher risk of transformation to acute myeloid leukemia (AML) when compared with general population. AML is the initial presentation in approximately one third of patients.
A 17 year old male presented to the emergency room with history of high grade fever since two weeks. Examination revealed pallor, short stature and thumb polydactyly. There was no visceromegaly or lymphadenopathy. Complete blood count showed haemoglobin 3.4 gm/dl, MCV 100 fl and MCH 36 pg, white blood cell count 55.9 × 10 E9/L and platelet count 8 × 10E9/L. Peripheral blood smear revealed 26% blast cells. Bone marrow was hypercellular exhibiting infiltration with 21% blast cells. Auer rods were seen in few blast cells. These findings were consistent with acute myelomonocytic leukemia. These blasts cells expressed CD33, CD13, HLA-DR, CD117, CD34 antigens and cytoplasmic myeloperoxidase on immunophenotyping. Bone marrow cytogenetics revealed 46, XY, t (8:21) (q22; q22)  / 46, XY, add (2) (q37), t (8; 21)  / 46, XY . Molecular studies showed positivity of FLT 3 D835 variant and negativity of NPM 1 and FLT3 ITD (internal tandem domain) mutation. Peripheral blood analysis for chromosomal breakage exhibited tri-radial and complex figures. He received induction chemotherapy with cytarabine and daunorubicin (3 + 7). Day 14 marrow revealed clearance of blast cells.
The recognition of specific cytogenetic abnormalities present in FA known to predispose to AML is crucial for early haematopoietic stem cell transplant (HSCT) before transformation to leukemia.
Fanconi anemia; Acute myeloid leukemia; Cytogenetic abnormalities
The RUNX1 transcription factor gene is frequently mutated in sporadic myeloid and lymphoid leukemia through translocation, point mutation or amplification. It is also responsible for a familial platelet disorder with predisposition to acute myeloid leukemia (FPD-AML). The disruption of the largely unknown biological pathways controlled by RUNX1 is likely to be responsible for the development of leukemia. We have used multiple microarray platforms and bioinformatic techniques to help identify these biological pathways to aid in the understanding of why RUNX1 mutations lead to leukemia.
Here we report genes regulated either directly or indirectly by RUNX1 based on the study of gene expression profiles generated from 3 different human and mouse platforms. The platforms used were global gene expression profiling of: 1) cell lines with RUNX1 mutations from FPD-AML patients, 2) over-expression of RUNX1 and CBFβ, and 3) Runx1 knockout mouse embryos using either cDNA or Affymetrix microarrays. We observe that our datasets (lists of differentially expressed genes) significantly correlate with published microarray data from sporadic AML patients with mutations in either RUNX1 or its cofactor, CBFβ. A number of biological processes were identified among the differentially expressed genes and functional assays suggest that heterozygous RUNX1 point mutations in patients with FPD-AML impair cell proliferation, microtubule dynamics and possibly genetic stability. In addition, analysis of the regulatory regions of the differentially expressed genes has for the first time systematically identified numerous potential novel RUNX1 target genes.
This work is the first large-scale study attempting to identify the genetic networks regulated by RUNX1, a master regulator in the development of the hematopoietic system and leukemia. The biological pathways and target genes controlled by RUNX1 will have considerable importance in disease progression in both familial and sporadic leukemia as well as therapeutic implications.
Retrospective analyses in non-randomised cohorts suggest that regimens containing fludarabine/Ara C and/or idarubicin/ara C may be more effective than daunorubicin/AraC (DA)-containing regimens in cases of acute myeloid leukaemia (AML) overexpressing p-glycoprotein (Pgp). We prospectively measured Pgp protein and function by flow cytometry in CD45-gated blasts from 434 AML15 trial patients randomised to remission induction therapy with two courses of FLAG-Ida or DA±etoposide (DA/ADE). In all, 34% were positive for Pgp protein and 38% for function. Pgp protein-positive cases had a higher incidence of resistant disease (14% vs 5%), adjusted odds ratio 2.67 (1.14–6.24). There was a trend towards a higher cumulative incidence of relapse at 5 years for Pgp-positive cases (46% vs 55%), adjusted hazard ratio 1.42 (0.98–2.07) (P=0.06). For patients treated with FLAG-Ida, the complete remission (CR) rate was 86% for both Pgp-positive and Pgp-negative patients. In patients treated with DA/ADE, 78% of Pgp-positive and 90% of Pgp-negative cases achieved CR (P=0.06). In analyses of overall survival, there was no interaction between treatment received and Pgp expression. Data for Pgp function followed similar trends. Our data suggest that FLAG-Ida may improve the remission rate for Pgp-positive AML, but the malignant clone is reduced rather than eradicated such that the relapse rate remains high in Pgp-positive patients.
p-glycoprotein; trial; AML; multi-drug resistance
Epigenetic modulations, including changes in DNA cytosine methylation, are implicated in the pathogenesis and progression of acute myeloid leukemia (AML). Azacitidine is a hypomethylating agent that is incorporated into RNA as well as DNA. Thus, there is a rationale to its use in patients with AML. We determined whether baseline and/or early changes in the methylation of long interspersed element (LINE)-1 or CDH13 correlate with bone marrow blast clearance, hematological response, or survival in patients with AML treated with azacitidine.
An open label, phase I/II trial was performed in 40 AML patients (median bone marrow blast count was 42%) unfit for intensive chemotherapy treated with azacitidine 75 mg/m2/day subcutaneously for 5 days every 4 weeks. Bone marrow mononuclear cell samples were taken on day 0 (pretreatment) and day 15 during the first treatment cycle; LINE-1 and CDH13 methylation levels were quantified by methylation-specific, semiquantitative, real-time polymerase chain reaction.
Treatment with azacitidine significantly reduced LINE-1 but not CDH13 methylation levels over the first cycle (P < 0.0001). Absolute LINE-1 methylation levels tended to be lower on day 0 (P = 0.06) and day 15 of cycle 1 (P = 0.03) in patients who went on to achieve subsequent complete remission, partial remission or hematological improvement versus patients with stable disease. However, the decrease in LINE-1 methylation over the first treatment cycle did not correlate with subsequent response (P = 0.31). Baseline methylation levels of LINE-1 or CDH13 did not correlate with disease-related prognostic factors, including cytogenetic risk, relapsed/refractory AML, or presence of NPM1 or FLT3 mutations. No correlation was observed between LINE-1 or CDH13 methylation levels and overall survival.
Analysis of baseline LINE-1 methylation levels may help identify elderly AML patients who are most likely to respond to azacitidine therapy.
DNA methylation; acute myeloid leukemia; azacitidine; clinical response; CDH13; LINE-1 methylation
A relevant role of septins in leukemogenesis has been uncovered by their involvement as fusion partners in MLL-related leukemia. Recently, we have established the MLL-SEPT2 gene fusion as the molecular abnormality subjacent to the translocation t(2;11)(q37;q23) in therapy-related acute myeloid leukemia. In this work we quantified MLL and SEPT2 gene expression in 58 acute myeloid leukemia patients selected to represent the major AML genetic subgroups, as well as in all three cases of MLL-SEPT2-associated myeloid neoplasms so far described in the literature.
Cytogenetics, fluorescence in situ hybridization (FISH) and molecular studies (RT-PCR, qRT-PCR and qMSP) were used to characterize 58 acute myeloid leukemia patients (AML) at diagnosis selected to represent the major AML genetic subgroups: CBFB-MYH11 (n = 13), PML-RARA (n = 12); RUNX1-RUNX1T1 (n = 12), normal karyotype (n = 11), and MLL gene fusions other than MLL-SEPT2 (n = 10). We also studied all three MLL-SEPT2 myeloid neoplasia cases reported in the literature, namely two AML patients and a t-MDS patient.
When compared with normal controls, we found a 12.8-fold reduction of wild-type SEPT2 and MLL-SEPT2 combined expression in cases with the MLL-SEPT2 gene fusion (p = 0.007), which is accompanied by a 12.4-fold down-regulation of wild-type MLL and MLL-SEPT2 combined expression (p = 0.028). The down-regulation of SEPT2 in MLL-SEPT2 myeloid neoplasias was statistically significant when compared with all other leukemia genetic subgroups (including those with other MLL gene fusions). In addition, MLL expression was also down-regulated in the group of MLL fusions other than MLL-SEPT2, when compared with the normal control group (p = 0.023)
We found a significant down-regulation of both SEPT2 and MLL in MLL-SEPT2 myeloid neoplasias. In addition, we also found that MLL is under-expressed in AML patients with MLL fusions other than MLL-SEPT2.
The leukemia-associated fusion protein RUNX1/ETO is generated by the chromosomal translocation t(8;21) which appears in about 12% of all de novo acute myeloid leukemias (AMLs). Essential for the oncogenic potential of RUNX1/ETO is the oligomerization of the chimeric fusion protein through the nervy homology region 2 (NHR2) within ETO. In previous studies, we have shown that the intracellular expression of peptides containing the NHR2 domain inhibits RUNX1/ETO oligomerization, thereby preventing cell proliferation and inducing differentiation of RUNX1/ETO transformed cells. Here, we show that introduction of a recombinant TAT-NHR2 fusion polypeptide into the RUNX1/ETO growth-dependent myeloid cell line Kasumi-1 results in decreased cell proliferation and increased numbers of apoptotic cells. This effect was highly specific and mediated by binding the TAT-NHR2 peptide to ETO sequences, as TAT-polypeptides containing the oligomerization domain of BCR did not affect cell proliferation or apoptosis in Kasumi-1 cells. Thus, the selective interference with NHR2-mediated oligomerization by peptides represents a challenging but promising strategy for the inhibition of the leukemogenic potential of RUNX1/ETO in t(8;21)-positive leukemia.
This study investigated the spectrum of chromosomal abnormalities in 325 leukemia patients and developed optimal profiles of leukemic fusion genes for multiplex RT-PCR. We prospectively analyzed blood and bone marrow specimens of patients with acute leukemia. Twenty types of chromosomal abnormalities were detected in 42% from all patients by commercially available multiplex RT-PCR for detecting 28 fusion genes and in 35% by cytogenetic analysis including FISH analysis. The most common cytogenetic aberrations in acute myeloid leukemia patients was PML/PARA, followed by AML1/MGT8 and MLL1, and in acute lymphoid leukemia patients was BCR/ABL, followed by TEL/AML1 and MLL1 gene rearrangement. Among the negative results for multiplex RT-PCR, clinically significant t(3;3)(q21;q26.2), t(8;14)(q24;q32) and i(17)(q10) were detected by conventional cytogenetics. The spectrum and frequency of chromosomal abnormalities in our leukemia patients are differed from previous studies, and may offer optimal profiles of leukemic fusion genes for the development of new molecular detection systems.
Leukemia; Chromosomal Abnormalities; Molecular Detection System
The presence of central nervous system (CNS) disease in pediatric acute myeloid leukemia (AML) is often thought to confer a worse prognosis. This study examined the outcome of children with AML who had CNS disease at diagnosis.
Patients enrolled on Children's Cancer Group protocols 2861, 2891, 2941 and 2961 being treated for de novo AML were classified for the presence of CNS disease at diagnosis as CNS1 (< 5 WBC in the CSF without blasts), CNS2 (< 5 WBC in the CSF with blasts) or CNS3 (≥5 WBC in the CSF with blasts). CNS disease at diagnosis was then analysed regarding patient characteristics and outcome.
There was an incidence of CNS disease (i.e., CNS3 status) of 11% in the 1459 patients analyzed in this study. The risk factors found are young age, high white cell count, hepatomegaly or splenomegaly at diagnosis, M4 subtype, chromosome 16 abnormalities and hyperdiploid cytogenetics. There were no significant differences in overall survival, event free survival, or remission rates between the groups; however, a significant difference was seen between the CNS1 and CNS3 groups in disease free survival and isolated CNS relapse risk.
Patients with CNS disease at diagnosis have similar survival to those without CNS disease, although they have an increased incidence of isolated CNS relapse. Patients with CNS disease at diagnosis may warrant more aggressive CNS directed therapy.
central nervous system; leukemia; AML; pediatric