Prognostic significance of, and gene and microRNA expression signatures associated with, CEBPA mutations in cytogenetically normal acute myeloid leukemia with high-risk molecular features: a Cancer and Leukemia Group B Study

Molecular evaluation of CEBPA gene mutation in normal karyotype acute myeloid leukemia: a comparison of two methods and report of novel CEBPA mutations from Indian acute myeloid leukemia patients

BACKGROUND AND AIM

Mutation in the CAAT/enhancer binding protein-α (CEBPA) gene has been reported as being one of the common genetic abnormalities in acute myeloid leukemia (AML) and is associated with a good clinical outcome. We intend to explore the prevalence of CEBPA mutations and evaluate the efficacy of fragment and sequencing analysis methods for CEBPA mutation detection in Indian AML patients.

MATERIALS AND METHODS

The coding region of the CEBPA gene was screened in 36 normal karyotype AML patients by fragment analysis and direct sequencing.

RESULTS

We identified five CEBPA sequence variations in three patient samples (8.3%) by direct sequencing analysis, of which three were novel mutations. These mutations were clustered mostly in the TAD1 and basic region leucine zipper region of the CEBPA protein. Six cases demonstrated a previously reported polymorphism. Two of the three positive cases showed double mutations, and one case had a single mutation. All five mutations were also detected by fragment analysis, indicating a sensitivity of 100% (5/5). No correlation with clinical parameters including age, sex, white blood cell count, hemoglobin, and platelet count between patients with and without mutation was observed. Interestingly, CEBPA mutations were significantly higher in patients with WT1 mutation, while no correlation with FLT3 and NPM1 was observed.

CONCLUSION

We report for the first time the frequency of CEBPA mutation from an Indian patients (8.3%). The identification of novel CEBPA mutations added new insights into the genetic heterogeneity of AML. Our result suggests that the optimal approach for detecting CEBPA mutations in AML can be a combination of fragment analysis and direct sequencing.

Acute myeloid leukemia and transcription factors: role of erythroid Krüppel-like factor (EKLF)

We have investigated the role of erythroid transcription factors mRNA expression in patients with acute myeloid leukemia (AML) in the context of cytogenetic and other prognostic molecular markers, such as FMS-like Tyrosine Kinase 3 (FLT3), Nucleophosmin 1 (NPM1), and CCAAT/enhance-binding protein α (CEBPA) mutations. Further validation of Erythroid Krüppel-like Factor (EKLF) mRNA expression as a prognostic factor was assessed.We evaluated GATA binding protein 1 (GATA1), GATA binding protein 2 (GATA2), EKLF and Myeloproliferative Leukemia virus oncogen homology (cMPL) gene mRNA expression in the bone marrow of 65 AML patients at diagnosis, and assessed any correlation with NPM1, FLT3 and CEBPA mutations. EKLF-positive AML was associated with lower WBC in peripheral blood (P = 0.049), a higher percentage of erythroblasts in bone marrow (p = 0.057), and secondary AMLs (P = 0.036). High expression levels of EKLF showed a trend to association with T-cell antigen expression, such as CD7 (P = 0.057). Patients expressing EKLF had longer Overall Survival (OS) and Event Free Survival (EFS) than those patients not expressing EKLF (median OS was 35.61 months and 19.31 months, respectively, P = 0.0241; median EFS was 19.80 months and 8.03 months, respectively, P = 0.0140). No correlation of GATA1, GATA2, EKLF and cMPL levels was observed with FLT-3 or NPM1 mutation status. Four of four CEBPA mutated AMLs were EKLF positive versus 10 of 29 CEBPA wild-type AMLs; three of the CEBPA mutated, EKLF-positive AMLs were also GATA2 positive. There were no cases of CEBPA mutations in the EKLF-negative AML group. In conclusion, we have validated EKLF mRNA expression as an independent predictor of outcome in AML, and its expression is not associated with FLT3-ITD and NPM1 mutations. EKLF mRNA expression in AML patients may correlate with dysregulated CEBPA.

MicroRNA-181b regulates NF-κB-mediated vascular inflammation

EC activation and dysfunction have been linked to a variety of vascular inflammatory disease states. The function of microRNAs (miRNAs) in vascular EC activation and inflammation remains poorly understood. Herein, we report that microRNA-181b (miR-181b) serves as a potent regulator of downstream NF-κB signaling in the vascular endothelium by targeting importin-α3, a protein that is required for nuclear translocation of NF-κB. Overexpression of miR-181b inhibited importin-α3 expression and an enriched set of NF-κB-responsive genes such as adhesion molecules VCAM-1 and E-selectin in ECs in vitro and in vivo. In addition, treatment of mice with proinflammatory stimuli reduced miR-181b expression. Rescue of miR-181b levels by systemic administration of miR-181b "mimics" reduced downstream NF-κB signaling and leukocyte influx in the vascular endothelium and decreased lung injury and mortality in endotoxemic mice. In contrast, miR-181b inhibition exacerbated endotoxin-induced NF-κB activity, leukocyte influx, and lung injury. Finally, we observed that critically ill patients with sepsis had reduced levels of miR-181b compared with control intensive care unit (ICU) subjects. Collectively, these findings demonstrate that miR-181b regulates NF-κB-mediated EC activation and vascular inflammation in response to proinflammatory stimuli and that rescue of miR-181b expression could provide a new target for antiinflammatory therapy and critical illness.

MAGIA²: from miRNA and genes expression data integrative analysis to microRNA-transcription factor mixed regulatory circuits (2012 update)

MAGIA² (http://gencomp.bio.unipd.it/magia2) is an update, extension and evolution of the MAGIA web tool. It is dedicated to the integrated analysis of in silico target prediction, microRNA (miRNA) and gene expression data for the reconstruction of post-transcriptional regulatory networks. miRNAs are fundamental post-transcriptional regulators of several key biological and pathological processes. As miRNAs act prevalently through target degradation, their expression profiles are expected to be inversely correlated to those of the target genes. Low specificity of target prediction algorithms makes integration approaches an interesting solution for target prediction refinement. MAGIA² performs this integrative approach supporting different association measures, multiple organisms and almost all target predictions algorithms. Nevertheless, miRNAs activity should be viewed as part of a more complex scenario where regulatory elements and their interactors generate a highly connected network and where gene expression profiles are the result of different levels of regulation. The updated MAGIA² tries to dissect this complexity by reconstructing mixed regulatory circuits involving either miRNA or transcription factor (TF) as regulators. Two types of circuits are identified: (i) a TF that regulates both a miRNA and its target and (ii) a miRNA that regulates both a TF and its target.

Epigenomics of leukemia: from mechanisms to therapeutic applications

Leukemogenesis is a multistep process in which successive transformational events enhance the ability of a clonal population arising from hematopoietic progenitor cells to proliferate, differentiate and survive. Clinically and pathologically, leukemia is subdivided into four main categories: chronic lymphocytic leukemia, chronic myeloid leukemia, acute lymphocytic leukemia and acute myeloid leukemia. Leukemia has been previously considered only as a genetic disease. However, in recent years, significant advances have been made in the elucidation of the leukemogenesis-associated processes. Thus, we have come to understand that epigenetic alterations including DNA methylation, histone modifications and miRNA are involved in the permanent changes of gene expression controlling the leukemia phenotype. In this article, we will focus on the epigenetic defects associated with leukemia and their implications as biomarkers for diagnostic, prognostic and therapeutic applications.

miR-3151 interplays with its host gene BAALC and independently affects outcome of patients with cytogenetically normal acute myeloid leukemia

High BAALC expression levels are associated with poor outcome in cytogenetically normal acute myeloid leukemia (CN-AML) patients. Recently, miR-3151 was discovered in intron 1 of BAALC. To evaluate the prognostic significance of miR-3151 expression levels and to gain insight into the biologic and prognostic interplay between miR-3151 and its host, miR-3151 and BAALC expression were measured in pretreatment blood of 179 CN-AML patients. Gene-expression profiling and miRNA-expression profiling were performed using microarrays. High miR-3151 expression was associated with shorter disease-free and overall survival, whereas high BAALC expression predicted failure of complete remission and shorter overall survival. Patients exhibiting high expression of both miR-3151 and BAALC had worse outcome than patients expressing low levels of either gene or both genes. In gene-expression profiling, high miR-3151 expressers showed down-regulation of genes involved in transcriptional regulation, posttranslational modification, and cancer pathways. Two genes, FBXL20 and USP40, were validated as direct miR-3151 targets. The results of the present study show that high expression of miR-3151 is an independent prognosticator for poor outcome in CN-AML and affects different outcome end points than its host gene, BAALC. The combination of both markers identified a patient subset with the poorest outcome. This interplay between an intronic miR and its host may have important biologic implications.

Heritable polymorphism predisposes to high BAALC expression in acute myeloid leukemia

Overexpression of the brain and acute leukemia, cytoplasmic (BAALC) gene is implicated in myeloid leukemogenesis and associated with poor outcome in both acute myeloid leukemia (AML) and acute lymphoblastic leukemia patients. Additionally, high BAALC expression occurs in glioblastoma, melanoma, and childhood gastrointestinal stroma tumors, suggesting an oncogenic role for BAALC. However, the mechanisms underlying the deregulated expression are unknown. We hypothesized that a common heritable genetic feature located in cis might account for overexpression of BAALC in an allele-specific manner. By sequencing the genomic region of BAALC we identified nine informative single nucleotide polymorphisms (SNPs) and tested them for a possible association with BAALC expression levels. We show that BAALC overexpression occurs in the presence of the T allele of SNP rs62527607[GT], which creates a binding site for the activating RUNX1 transcription factor in the BAALC promoter region. The mechanism is demonstrated experimentally in vitro using luciferase reporter assays and electrophoretic mobility shift assay (EMSA) analysis. The association of high BAALC expression with the T allele and its correlations with RUNX1 expresser status are shown in vivo in a test set (n = 253) and validation set (n = 105) of samples from cytogenetically normal AML patients from different populations. Thus, we identify a heritable genomic feature predisposing to overexpression of an oncogene, thereby possibly leading to enhanced AML leukemogenesis. Our findings further suggest that genomic variants might become useful tools in the practice of personalized medicine.

Diagnostic and prognostic value of cytogenetics in acute myeloid leukemia

The last 4 decades have seen major advances in understanding the genetic basis of acute myeloid leukemia (AML), and substantial improvements in survival of children and young adults with the disease. A key step forward was the discovery that AML cells harbor recurring cytogenetic abnormalities. The identification of the genes involved in chromosomal rearrangements has provided insights into the regulation of normal hematopoiesis and how disruption of key transcription factors and epigenetic modulators promote leukemic transformation. Cytogenetics has been widely adopted to provide the framework for development of risk-stratified treatment approaches to patient management.

C/EBPα dysregulation in AML and ALL

The transcription factor CCAAT/enhancer binding protein a (C/EBPα) is a critical regulator of myeloid development, directing granulocyte, and monocyte differentiation. As such, it is dysregulated in more than half of patients with acute myeloid leukemia (AML). C/EBPα expression is suppressed as result of common leukemia-associated genetic and epigenetic alterations such as AML1-ETO, BCR-ABL, FLT3-ITD, or CEBPA promoter methylation. In addition, 10-15% of patients with AML with intermediate risk cytogenetics are characterized by mutations of the CEBPA gene. Two classes of mutations are described. N-terminal changes result in expression of a truncated dominant negative C/EBPαp30 isoform. C-terminal mutations are in-frame insertions or deletions resulting in alteration of the leucine zipper preventing dimerization and DNA binding. Often, patients carry both N- and C-terminal mutations each affecting a different allele, and a mouse model recapitulates the human phenotype. Patients with mutated CEBPA AML comprise a clinically distinct group with favorable outcome consistently seen in patients with biallelic mutations. In addition, C/EBP family members are aberrantly expressing from the immunoglobulin heavy chain locus in 2% of pre-B ALLs. This review summarizes the normal hematopoietic developmental pathways regulated by C/EBPα and discusses the molecular pathways involved in mutated CEBPA AML and ALL.

Age-related prognostic impact of different types of DNMT3A mutations in adults with primary cytogenetically normal acute myeloid leukemia

PURPOSE

To determine the frequency of DNMT3A mutations, their associations with clinical and molecular characteristics and outcome, and the associated gene- and microRNA-expression signatures in primary cytogenetically normal acute myeloid leukemia (CN-AML).

PATIENTS AND METHODS

Four hundred fifteen previously untreated adults were analyzed for DNMT3A mutations and established prognostic gene mutations and expression markers. Gene- and microRNA-expression profiles were derived using microarrays.

RESULTS

Younger (< 60 years; n = 181) and older (≥ 60 years; n = 234) patients had similar frequencies of DNMT3A mutations (35.3% v 33.3%). Missense mutations affecting arginine codon 882 (R882-DNMT3A) were more common (n = 92; 62%) than those affecting other codons (non-R882-DNMT3A). DNMT3A-mutated patients did not differ regarding complete remission rate, but had shorter disease-free survival (DFS; P = .03) and, by trend, overall survival (OS; P = .07) than DNMT3A-wild-type patients. In multivariable analyses, DNMT3A mutations remained associated with shorter DFS (P = .01), but not with shorter OS. When analyzed separately, the two DNMT3A mutation types had different significance by age group. Younger patients with non-R882-DNMT3A mutations had shorter DFS (P = .002) and OS (P = .02), whereas older patients with R882-DNMT3A mutations had shorter DFS (P = .005) and OS (P = .002) after adjustment for other clinical and molecular prognosticators. Gene- and microRNA-expression signatures did not accurately predict DNMT3A mutational status.

CONCLUSION

DNMT3A mutations are frequent in CN-AML, and their clinical significance seems to be age dependent. DNMT3A-R882 mutations are associated with adverse prognosis in older patients, and non-R882-DNMT3A mutations are associated with adverse prognosis in younger patients. Low accuracy of gene- and microRNA-expression signatures in predicting DNMT3A mutation status suggested that the role of these mutations in AML remains to be elucidated.

Up-regulation of a HOXA-PBX3 homeobox-gene signature following down-regulation of miR-181 is associated with adverse prognosis in patients with cytogenetically abnormal AML

Increased expression levels of miR-181 family members have been shown to be associated with favorable outcome in patients with cytogenetically normal acute myeloid leukemia. Here we show that increased expression of miR-181a and miR-181b is also significantly (P < .05; Cox regression) associated with favorable overall survival in cytogenetically abnormal AML (CA-AML) patients. We further show that up-regulation of a gene signature composed of 4 potential miR-181 targets (including HOXA7, HOXA9, HOXA11, and PBX3), associated with down-regulation of miR-181 family members, is an independent predictor of adverse overall survival on multivariable testing in analysis of 183 CA-AML patients. The independent prognostic impact of this 4-homeobox-gene signature was confirmed in a validation set of 271 CA-AML patients. Furthermore, our in vitro and in vivo studies indicated that ectopic expression of miR-181b significantly promoted apoptosis and inhibited viability/proliferation of leukemic cells and delayed leukemogenesis; such effects could be reversed by forced expression of PBX3. Thus, the up-regulation of the 4 homeobox genes resulting from the down-regulation of miR-181 family members probably contribute to the poor prognosis of patients with nonfavorable CA-AML. Restoring expression of miR-181b and/or targeting the HOXA/PBX3 pathways may provide new strategies to improve survival substantially.

Allogeneic stem cell transplantation in first complete remission

PURPOSE OF REVIEW

The optimal postremission therapy of acute myeloid leukemia (AML) in first complete remission (CR1) is uncertain. This review summarizes the recent developments in the clinical research and therapeutic applications defining the role of allogeneic hematopoietic stem cell transplantation (allo-HCT) in CR1.

RECENT FINDINGS

Molecular markers in combinations with cytogenetics have improved the risk stratification and informed decision-making in patients with AML in CR1. In parallel, several important advances in the transplant field, such as better supportive care, improved transplant technology, increased availability of alternative donors, and reduced-intensity conditioning, have improved the safety as well as access of allo-HCT for a larger number of patients.

SUMMARY

The progress in risk stratification and in transplant technology dictate that early donor identification search should be initiated for all eligible AML patients in CR1.

Prognostic implications of genetic aberrations in acute myelogenous leukemia with normal cytogenetics

Acute myelogenous leukemia (AML) is a genetically heterogeneous disease in which somatic mutations, that disturb cellular growth, proliferation, and differentiation, accumulate in hematopoietic progenitor cells. Cytogenetic findings, at diagnosis, have been proven to be one of the most important prognostic indicators in AML. About half of the patients with AML are found to have "normal" cytogenetic analysis by standard culture techniques. These patients are considered as an intermediate risk group. Cytogenetically normal AML (CN-AML) is the largest cytogenetic risk group, and the variation in clinical outcome of patients in this group is greater than in any other cytogenetic group. Besides mutation testing, age and presenting white blood cell count are important predictors of overall survival, suggesting that other factors independent of cytogenetic abnormalities, contribute to the outcome of patients with AML. The expanding knowledge at the genetic and molecular levels is helping define several subgroups of patients with CN-AML with variable prognosis. In this review, we describe the clinical and prognostic characteristics of CN-AML patients as a group, as well as the various molecular and genetic aberrations detected in these patients and their clinical and prognostic implications.

ASXL1 mutations identify a high-risk subgroup of older patients with primary cytogenetically normal AML within the ELN Favorable genetic category

The associations of mutations in the enhancer of trithorax and polycomb family gene ASXL1 with pretreatment patient characteristics, outcomes, and gene-/microRNA-expression profiles in primary cytogenetically normal acute myeloid leukemia (CN-AML) are unknown. We analyzed 423 adult patients for ASXL1 mutations, other prognostic gene mutations, and gene-/microRNA-expression profiles. ASXL1 mutations were 5 times more common in older (≥ 60 years) patients (16.2%) than those younger than 60 years (3.2%; P < .001). Among older patients, ASXL1 mutations associated with wild-type NPM1 (P < .001), absence of FLT3-internal tandem duplications (P = .002), mutated CEBPA (P = .01), and with inferior complete remission (CR) rate (P = .04), disease-free survival (DFS; P = .03), overall survival (OS; P = .006), and event-free survival (EFS; P = .002). Within the European LeukemiaNet (ELN) genetic categories of older CN-AML, ASXL1 mutations associated with inferior CR rate (P = .02), OS (P < .001), and EFS (P < .001) among ELN Favorable, but not among ELN Intermediate-I patients. Multivariable analyses confirmed associations of ASXL1 mutations with unfavorable CR rate (P = .03), DFS (P < .001), OS (P < .001), and EFS (P < .001) among ELN Favorable patients. We identified an ASXL1 mutation-associated gene-expression signature, but no microRNA-expression signature. This first study of ASXL1 mutations in primary CN-AML demonstrates that ASXL1-mutated older patients, particularly within the ELN Favorable group, have unfavorable outcomes and may be candidates for experimental treatment approaches.

Clinical outcome and gene- and microRNA-expression profiling according to the Wilms tumor 1 (WT1) single nucleotide polymorphism rs16754 in adult de novo cytogenetically normal acute myeloid leukemia: a Cancer and Leukemia Group B study

BACKGROUND

The alleles of the Wilms tumor 1 (WT1) polymorphism rs16754 harbor adenine (A) or guanine (G). Recently, rs16754 has been reported to affect the outcome of patients with cytogenetically normal acute myeloid leukemia. To validate this finding, we investigated pretreatment features and outcome associated with rs16754 in a large cohort of patients with cytogenetically normal acute myeloid leukemia.

DESIGN AND METHODS

Four-hundred and thirty-three intensively treated and molecularly characterized cytogenetically normal patients with de novo acute myeloid leukemia (18-83 years old) were analyzed for rs16754. To gain biological insights, we studied the gene- and microRNA-expression profiles for associations with rs16754.

RESULTS

Three-hundred and nine (71%) patients were homozygous for A (WT1(AA)), 112 (26%) were heterozygous (WT1(AG)) and 12 (3%) were homozygous for G (WT1(GG)). For comparison with previous studies, we grouped WT1(AG) and WT1(GG) patients and compared them with WT1(AA) patients divided into younger (<60 years) and older (≥60 years) adults. We found no independent prognostic impact of WT1(AA). However, WT1(GG) patients, who were less often Caucasian than WT1(AG) (P=0.001) or WT1(AA) (P=0.008) patients, and had TET2 mutations more often than WT1(AG) (P=0.02) patients, had, among patients with FLT3-internal tandem duplication and/or NPM1 wild-type, better disease-free (P=0.02) and overall survival (P=0.04) than WT1(AA) and WT1(AG) patients combined. Unsupervised and supervised analyses of the gene- and microRNA-expression profiles suggested that there were no distinct expression patterns associated with any rs16754 genotype.

CONCLUSIONS

We did not observe the previously reported adverse impact of WT1(AA) but found favorable outcomes associated with the homozygous WT1(GG). Considering its low frequency, confirmatory studies are necessary. The biological significance of rs16754 remains questionable as no distinct expression profiles were associated with the genotypes.

NUP98 gene fusions and hematopoietic malignancies: common themes and new biologic insights

Structural chromosomal rearrangements of the Nucleoporin 98 gene (NUP98), primarily balanced translocations and inversions, are associated with a wide array of hematopoietic malignancies. NUP98 is known to be fused to at least 28 different partner genes in patients with hematopoietic malignancies, including acute myeloid leukemia, chronic myeloid leukemia in blast crisis, myelodysplastic syndrome, acute lymphoblastic leukemia, and bilineage/biphenotypic leukemia. NUP98 gene fusions typically encode a fusion protein that retains the amino terminus of NUP98; in this context, it is important to note that several recent studies have demonstrated that the amino-terminal portion of NUP98 exhibits transcription activation potential. Approximately half of the NUP98 fusion partners encode homeodomain proteins, and at least 5 NUP98 fusions involve known histone-modifying genes. Several of the NUP98 fusions, including NUP98-homeobox (HOX)A9, NUP98-HOXD13, and NUP98-JARID1A, have been used to generate animal models of both lymphoid and myeloid malignancy; these models typically up-regulate HOXA cluster genes, including HOXA5, HOXA7, HOXA9, and HOXA10. In addition, several of the NUP98 fusion proteins have been shown to inhibit differentiation of hematopoietic precursors and to increase self-renewal of hematopoietic stem or progenitor cells, providing a potential mechanism for malignant transformation.

Current findings for recurring mutations in acute myeloid leukemia

The development of acute myeloid leukemia (AML) is a multistep process that requires at least two genetic abnormalities for the development of the disease. The identification of genetic mutations in AML has greatly advanced our understanding of leukemogenesis. Recently, the use of novel technologies, such as massively parallel DNA sequencing or high-resolution single-nucleotide polymorphism arrays, has allowed the identification of several novel recurrent gene mutations in AML. The aim of this review is to summarize the current findings for the identification of these gene mutations (Dnmt, TET2, IDH1/2, NPM1, ASXL1, etc.), most of which are frequently found in cytogenetically normal AML. The cooperative interactions of these molecular aberrations and their interactions with class I/II mutations are presented. The prognostic and predictive significances of these aberrations are also reviewed.

Stem cell gene expression programs influence clinical outcome in human leukemia

Xenograft studies indicate that some solid tumors and leukemias are organized as cellular hierarchies sustained by cancer stem cells (CSCs). Despite the promise of the CSC model, its relevance in humans remains uncertain. Here we show that acute myeloid leukemia (AML) follows a CSC model on the basis of sorting multiple populations from each of 16 primary human AML samples and identifying which contain leukemia stem cells (LSCs) using a sensitive xenograft assay. Analysis of gene expression from all functionally validated populations yielded an LSC-specific signature. Similarly, a hematopoietic stem cell (HSC) gene signature was established. Bioinformatic analysis identified a core transcriptional program shared by LSCs and HSCs, revealing the molecular machinery underlying 'stemness' properties. Both stem cell programs were highly significant independent predictors of patient survival and were found in existing prognostic signatures. Thus, determinants of stemness influence the clinical outcome of AML, establishing that LSCs are clinically relevant and not artifacts of xenotransplantation.

Expression of HOXB genes is significantly different in acute myeloid leukemia with a partial tandem duplication of MLL vs. a MLL translocation: a cross-laboratory study

In acute myeloid leukemia (AML), the mixed lineage leukemia (MLL) gene may be rearranged to generate a partial tandem duplication (PTD), or fused to partner genes through a chromosomal translocation (tMLL). In this study, we first explored the differentially expressed genes between MLL-PTD and tMLL using gene expression profiling of our cohort (15 MLL-PTD and 10 tMLL) and one published data set. The top 250 probes were chosen from each set, resulting in 29 common probes (21 unique genes) to both sets. The selected genes include four HOXB genes, HOXB2, B3, B5, and B6. The expression values of these HOXB genes significantly differ between MLL-PTD and tMLL cases. Clustering and classification analyses were thoroughly conducted to support our gene selection results. Second, as MLL-PTD, FLT3-ITD, and NPM1 mutations are identified in AML with normal karyotypes, we briefly studied their impact on the HOXB genes. Another contribution of this study is to demonstrate that using public data from other studies enriches samples for analysis and yields more conclusive results.

MicroRNA-335 acts as a metastasis suppressor in gastric cancer by targeting Bcl-w and specificity protein 1

Aberrant expression of miR-335 has been frequently reported in cancer studies, suggesting that there is a close correlation between miR-335 and cancer during its development, progression, metastasis and prognosis. The expression of miR-335 in gastric cancer and its effects are not known. Relative expression of miR-335 in 4 gastric cancer cell lines and in 70 gastric cancer tissues was confirmed by real-time quantitative reverse transcriptase-PCR compared with controls. Transwell cell migration and Matrigel invasion assay in vitro and metastasis formation assay in vivo were used to examine the effects of miR-335 expression on gastric cancer cell invasion and metastasis. The effect of miR-335 expression on gastric cancer cell proliferation was estimated by the 3-(4,5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay. Luciferase reporter assay and western blot were used to examine the potential target genes and related pathways. Gene silencing with small-interfering RNA was used to examine the effects of target genes on gastric cancer cell invasion. miR-335 was dramatically downregulated in gastric cancer cell lines than in the normal gastric cell line GES-1. Low expression of miR-335 was significantly associated with lymph-node metastasis, poor pT stage, poor pN stage and invasion of lymphatic vessels. Overexpression of miR-335 suppressed gastric cancer cell invasion and metastasis in vitro and in vivo, but has no significant effects on cell proliferation. Furthermore, miR-335 might suppress gastric cancer invasion and metastasis by targeting Bcl-w and specificity protein 1 (SP1). Taken together, our results provide evidence that miR-335 might function as a metastasis suppressor in gastric cancer by targeting SP1 directly and indirectly through the Bcl-w-induced phosphoinositide 3-kinase-Akt-Sp1 pathway. miR-335 showing altered expression at different stages of gastric cancer could be a target for gastric cancer therapies and could be further developed as a potential prognostic factor.

Long-Term Prognosis of Acute Myeloid Leukemia According to the New Genetic Risk Classification of the European LeukemiaNet Recommendations: Evaluation of the Proposed Reporting System

Purpose

The current European LeukemiaNet (ELN) recommendations for acute myeloid leukemia (AML) propose a new risk reporting system, integrating molecular and cytogenetic factors and subdividing the large heterogenous group of intermediate-risk patients into intermediate-I (IR-I) and intermediate-II (IR-II). We assessed the prognostic value of the new risk classification in a large cohort of patients.

Patients and Methods

Complete data for classification were available for 1,557 of 1,862 patients treated in the AML96 trial. Patients were assigned to the proposed genetic groups from the ELN recommendations, and survival analyses were performed using the Kaplan-Meier method and log-rank test for significance testing.

Results

The median age of all patients was 67 years. With a median follow-up of 8.3 years, significant differences between all risk categories were observed in patients age ≤ 60 years regarding the time to relapse, relapse-free survival, and overall survival (OS). Patients in the IR-II group had a better prognosis than patients in the IR-I group. The median OS times in young patients with favorable risk (FR), IR-I, IR-II, and adverse risk (AR) were 5.3, 1.1, 1.6, and 0.5 years, respectively. Separate analyses in the age group older than 60 years revealed significant differences between FR, AR, and IR as a whole, but not between IR-I and IR-II.

Conclusion

In younger patients with AML, the ELN classification seems to be the best available framework for prognostic estimations to date. Caution is advised concerning its use for prospective treatment allocation before it has been prospectively validated. In elderly patients, alternative prognostic factors are desirable for further risk stratification of IR.

Strategy for robust detection of insertions, deletions, and point mutations in CEBPA, a GC-rich content gene, using 454 next-generation deep-sequencing technology

CEBPA mutations are of prognostic relevance in acute myeloid leukemia (AML) and are currently detected using a combination of denaturing high-performance liquid chromatography (DHPLC), gene scan/fragment length analysis, and direct Sanger sequencing. Next-generation deep pyrosequencing, principally, allows for the highly sensitive detection of molecular mutations. However, standard 454 chemistry laboratory procedures lack efficient amplification of guanine-cytosine (GC)-rich amplicons during the emulsion PCR (emPCR) steps allowing direct massively parallel clonal amplification of PCR products. To solve this problem, we investigated six distinct emPCR conditions. The coding sequence of CEBPA was subdivided into four overlapping amplicons: GC content for amplicon 1, 74%; amplicon 2, 76%; amplicon 3, 77%; and amplicon 4, 69%. A new emPCR condition, improving the standard titanium assay, presents a robust solution to sequence amplicons with a GC content of up to 77%. Moreover, this assay was subsequently tested on a larger independent cohort of 23 AML patients. For each patient, a median of 737 reads was generated (coverage range, 397-fold to 1194-fold) and therefore allowed a robust detection of insertions, deletions, and point mutations. In conclusion, next-generation amplicon sequencing enables the highly sensitive detection of molecular mutations and is a feasible assay for routine assessment of GC-rich content amplicons.

Molecular diagnosis and prognosis with DNA microarrays

Microarray analysis makes it possible to determine thousands of gene expression values simultaneously. Changes in gene expression, as a response to diseases, can be detected allowing a better understanding and differentiation of diseases at a molecular level. By comparing different kinds of tissue, for example healthy tissue and cancer tissue, the microarray analysis indicates induced gene activity, repressed gene activity or when there is no change in the gene activity level. Fundamental patterns in gene expression are extracted by several clustering and machine learning algorithms. Certain kinds of cancer can be divided into subtypes, with different clinical outcomes, by their specific gene expression patterns. This enables a better diagnosis and tailoring of individual patient treatments.

An integrated genomic approach to the assessment and treatment of acute myeloid leukemia

Traditionally, new scientific advances have been applied quickly to the leukemias based on the ease with which relatively pure samples of malignant cells can be obtained. Currently, our arsenal of approaches used to characterize an individual's acute myeloid leukemia (AML) combines hematopathologic evaluation, flow cytometry, cytogenetic analysis, and molecular studies focused on a few key genes. The advent of high-throughput methods capable of full-genome evaluation presents new options for a revolutionary change in the way we diagnose, characterize, and treat AML. Next-generation DNA sequencing techniques allow full sequencing of a cancer genome or transcriptome, with the hope that this will be affordable for routine clinical care within the decade. Microarray-based testing will define gene and miRNA expression, DNA methylation patterns, chromosomal imbalances, and predisposition to disease and chemosensitivity. The vision for the future entails an integrated and automated approach to these analyses, bringing the possibility of formulating an individualized treatment plan within days of a patient's initial presentation. With these expectations comes the hope that such an approach will lead to decreased toxicities and prolonged survival for patients.

Deficient CEBPA DNA binding function in normal karyotype AML patients is associated with favorable prognosis

CCAAT/enhancer binding protein-α (CEBPA) mutations in acute myeloid leukemia (AML) patients with a normal karyotype (NK) confer favorable prognosis, whereas NK-AML patients per se are of intermediate risk. This suggests that blocked CEBPA function characterizes NK-AML with favorable outcome. We determined the prognostic significance of CEBPA DNA binding function by enzyme-linked immunosorbent assay in 105 NK-AML patients. Suppressed CEBPA DNA binding was defined by 21 good-risk AML patients with inv(16) or t(8;21) (both abnormalities targeting CEBPA) and 8 NK-AML patients with dominant-negative CEBPA mutations. NK-AML patients with suppressed CEBPA function showed a better overall survival (P = .0231) and disease-free survival (P = .0069) than patients with conserved CEBPA function. Suppressed CEBPA DNA binding was an independent marker for better overall survival and disease-free survival in a multivariable analysis that included FLT3-ITD, NPM1 and CEBPA mutation status, white blood cell count, age and lactate dehydrogenase. These data indicate that suppressed CEBPA function is associated with favorable prognosis in NK-AML patients.

Integrative prognostic risk score in acute myeloid leukemia with normal karyotype

To integrate available clinical and molecular information for cytogenetically normal acute myeloid leukemia (CN-AML) patients into one risk score, 275 CN-AML patients from multicenter treatment trials AML SHG Hannover 0199 and 0295 and 131 patients from HOVON/SAKK protocols as external controls were evaluated for mutations/polymorphisms in NPM1, FLT3, CEBPA, MLL, NRAS, IDH1/2, and WT1. Transcript levels were quantified for BAALC, ERG, EVI1, ID1, MN1, PRAME, and WT1. Integrative prognostic risk score (IPRS) was modeled in 181 patients based on age, white blood cell count, mutation status of NPM1, FLT3-ITD, CEBPA, single nucleotide polymorphism rs16754, and expression levels of BAALC, ERG, MN1, and WT1 to represent low, intermediate, and high risk of death. Complete remission (P = .005), relapse-free survival (RFS, P < .001), and overall survival (OS, P < .001) were significantly different for the 3 risk groups. In 2 independent validation cohorts of 94 and 131 patients, the IPRS predicted different OS (P < .001) and RFS (P < .001). High-risk patients with related donors had longer OS (P = .016) and RFS (P = .026) compared with patients without related donors. In contrast, intermediate-risk group patients with related donors had shorter OS (P = .003) and RFS (P = .05). Donor availability had no impact on outcome of patients in the low-risk group. Thus, the IPRS may improve consolidation treatment stratification in CN-AML patients. Study registered at www.clinicaltrials.gov as #NCT00209833.

Role of microRNAs in hematological malignancies

microRNAs (miRNAs) are short noncoding RNAs that function as post-transcriptional negative regulators of gene expression. They have been shown to be involved in the control of cell proliferation and differentiation, as well as acting as oncogenes or tumor-suppressor genes, suggesting their involvement in cancer development and progression. Expression profiles of human miRNAs have shown that many of them are aberrantly expressed in hematological malignancies. Therefore, miRNA profiling may be useful to distinguish between normal and tumor cells, and to create signatures for a variety of leukemia subtypes. Here, we review recent evidence for the involvement of miRNAs in the pathogenesis of different hematopoietic malignancies and their potential applications in diagnosis, prognosis and therapy of human leukemia.

Functional implications of microRNAs in acute myeloid leukemia by integrating microRNA and messenger RNA expression profiling

BACKGROUND

The expression of microRNAs (miRNAs) is deregulated in acute myeloid leukemia (AML), but the corresponding functional miRNA-controlled pathways are poorly understood. Integration of messenger RNA (mRNA) and miRNA expression profiling may allow the identification of functional links between the whole transcriptome and microRNome that are involved in myeloid leukemogenesis.

METHODS

We integrated miRNA and mRNA expression profiles obtained from 48 newly diagnosed AML patients by using 2 different microarray platforms and performed correlation, gene ontology, and network analysis. Experimental validation was also performed in AML cell lines using miRNA oligonucleotide mimics and functional assays.

RESULTS

Our analysis identified a strong positive correlation between HOX-related genes and miR-10 and miR-20a. Furthermore, we observed a negative correlation between miR-181a and miR-181b, miR-155, and miR-146 expression with that of genes involved in immunity and inflammation (eg, IRF7 and TLR4) and a positive correlation between miR-23a, miR-26a, miR-128a, and miR-145 expression with that of proapoptotic genes (eg, BIM and PTEN). These correlations were confirmed by gene ontology analyses, which revealed the enrichment of members of the homeobox, immunity and inflammation, and apoptosis biological processes. Furthermore, we validated experimentally the association of miR-145, miR-26a, and miR-128a with apoptosis in AML.

CONCLUSION

Our results indicate that by integrating the transcriptome and microRNome in AML cells, it is possible to identify previously unidentified putative functional miRNA-mRNA interactions in AML.

First report of multiple CEBPA mutations contributing to donor origin of leukemia relapse after allogeneic hematopoietic stem cell transplantation

Donor cell leukemia after allogeneic hematopoietic stem cell transplantation might provide a unique human model for our understanding of leukemogenesis in vivo. We hypothesized that the "2-genetic-hits model" may contribute to the "leukemization" of donor cells and first evaluated these genetic mutations that are implicated in the development of acute myeloid leukemia in a donor cell leukemia patient and donor. The patient and his donor-sister both harbored a germline mutation in CEBPA (584_589dup). Susceptible donor hematopoietic cells evolved to overt acute myeloid leukemia by developing 2 somatic CEBPA mutations (247dupC and 914_916dup) in the patient's microenvironment. These were identical to the acquired mutations identified in leukemic cells that originated from the patient during de novo acute myeloid leukemia. Our results provide the first report of multiple mutations of CEBPA contributing to the transformation of donor cells to the leukemic phenotype and provide clues to support the multiple-genetic-hits mechanism of donor cell leukemia.

TET2 mutations improve the new European LeukemiaNet risk classification of acute myeloid leukemia: a Cancer and Leukemia Group B study

PURPOSE

To determine the frequency of TET2 mutations, their associations with clinical and molecular characteristics and outcome, and the associated gene- and microRNA-expression signatures in patients with primary cytogenetically normal acute myeloid leukemia (CN-AML).

PATIENTS AND METHODS

Four-hundred twenty-seven patients with CN-AML were analyzed for TET2 mutations by polymerase chain reaction and direct sequencing and for established prognostic gene mutations. Gene- and microRNA-expression profiles were derived using microarrays.

RESULTS

TET2 mutations, found in 23% of patients, were associated with older age (P < .001) and higher pretreatment WBC (P = .04) compared with wild-type TET2 (TET2-wt). In the European LeukemiaNet (ELN) favorable-risk group (patients with CN-AML who have mutated CEBPA and/or mutated NPM1 without FLT3 internal tandem duplication [FLT3-ITD]), TET2-mutated patients had shorter event-free survival (EFS; P < .001) because of a lower complete remission (CR) rate (P = .007), and shorter disease-free survival (DFS; P = .003), and also had shorter overall survival (P = .001) compared with TET2-wt patients. TET2 mutations were not associated with outcomes in the ELN intermediate-I-risk group (CN-AML with wild-type CEBPA and wild-type NPM1 and/or FLT3-ITD). In multivariable models, TET2 mutations were associated with shorter EFS (P = .004), lower CR rate (P = .03), and shorter DFS (P = .05) only among favorable-risk CN-AML patients. We identified a TET2 mutation-associated gene-expression signature in favorable-risk but not in intermediate-I-risk patients and found distinct mutation-associated microRNA signatures in both ELN groups.

CONCLUSION

TET2 mutations improve the ELN molecular-risk classification in primary CN-AML because of their adverse prognostic impact in an otherwise favorable-risk patient subset. Our data suggest that these patients may be candidates for alternative therapies.

Identification of a risk dependent microRNA expression signature in myelodysplastic syndromes

The myelodysplastic syndromes (MDS) display both haematological and biological heterogeneity with variable leukaemia potential. MicroRNAs play an important role in tumour suppression and the regulation of self-renewal and differentiation of haematopoietic progenitors. Using a microarray platform, we evaluated microRNA expression from 44 patients with MDS and 17 normal controls. We identified a thirteen microRNA signature with statistically significant differential expression between normal and MDS specimens (P < 0·01), including down-regulation of members of the leukaemia-associated MIRLET7 family. A unique signature consisting of 10 microRNAs was closely associated with International Prognostic Scoring System (IPSS) risk category permitting discrimination between lower (Low/Intermediate-1) and higher risk (Intermediate-2/High) disease (P < 0·01). Selective overexpression of MIR181 family members was detected in higher risk MDS, indicating pathogenetic overlap with acute myeloid leukaemia. Survival analysis of an independent cohort of 22 IPSS lower risk MDS patients revealed a median survival of 3·5 years in patients with high expression of MIR181 family compared to 9·3 years in patients with low MIR181 expression (P = 0·002). Our pilot study suggested that analysis of microRNA expression profile offers diagnostic utility, and provide pathogenetic and prognostic discrimination in MDS.

Molecular genetics of adult acute myeloid leukemia: prognostic and therapeutic implications

Molecular analyses of leukemic blasts from patients with acute myeloid leukemia (AML) have revealed a striking heterogeneity with regard to the presence of acquired gene mutations and changes in gene and microRNA expression. Multiple submicroscopic genetic alterations with prognostic significance have been discovered. Application of gene- and microRNA profiling has identified genome-wide expression signatures that separate cytogenetic and molecular subsets of patients with AML into previously unrecognized biologic and/or prognostic subgroups. These and similar future findings are likely to have a major impact on the clinical management of AML because many of the identified genetic alterations not only represent independent prognosticators, but also may constitute targets for specific therapeutic intervention. In this report, we review genetic findings in AML and discuss their clinical implications.

New Prognostic Markers in Acute Myeloid Leukemia: Perspective from the Clinic

Acute myeloid leukemia (AML) is a disease with marked heterogeneity in both response to therapy and survival. Cytogenetics, age, and performance status have long determined prognosis and therapy. The advent of molecular diagnostics has heralded an explosion in new prognostic factors, including gene mutations in KIT, FLT3 (Fms-like tyrosine kinase 3), NPM1 (nucleophosmin 1), and CEBPA (CCAAT enhancer-binding protein-α). Microarray technology can now identify unique gene expression signatures associated with prognosis. Similarly microRNA expression, single nucleotide polymorphism arrays, and DNA methylation signatures have recently described important new prognostic subgroups of AML, and are contributing to our understanding of AML disease biology. Combined with proteomic profiling, these technologies have helped identify new targets and signaling pathways, and may soon help to identify individual patients likely to benefit from specific therapies, including allogeneic hematopoietic cell transplantation. In summary, new clinical and molecular prognostic markers have begun to significantly improve our understanding of AML biology. We are now close to a time when we will be able to use these prognostic factors and technologies to identify new targets for therapy and to determine who may benefit from that therapy, and ultimately change how we treat individual patients with AML.

Molecular pathogenesis of acute myeloid leukemia: a diverse disease with new perspectives

Acute myeloid leukemia (AML) is a very heterogeneous neoplasm of the hematopoietic stem cell. Despite important achievements in the treatment of AML, the long term survival of patients with the disease remains poor. Understanding the pathogenesis of AML better is crucial for finding new treatment approaches. During AML development, hematopoietic precursor cells undergo clonal transformation in a multistep process through acquisition of chromosomal rearrangements and/or different gene mutations. Over recent years, novel gene mutations have been found in patients with AML. These mutations can be divided into two important categories, class I mutations that confer a proliferation advantage and class II mutations that inhibit myeloid differentiation. Screening for some of these mutations is now part of the initial diagnostic workup in newly diagnosed AML patients. Information about the mutation status of specific genes is useful for risk-stratification, minimal residual disease (MRD) monitoring and increasingly also for targeted therapy, especially for patients with cytogenetically normal AML (CN-AML). Besides chromosomal rearrangements and gene mutations, epigenetic regulation of genes - meaning changes in gene expression by mechanisms other than changes in the underlying DNA sequence - also represents an important mechanism of leukemogenesis. This article reviews some of the most common mutations in CN-AML and gives a perspective of the translation of these discoveries from bench to bedside.

Allogeneic hematopoietic cell transplantation for adults with acute myeloid leukemia: myths, controversies, and unknowns

Progress in the last decade has improved the understanding of leukemia biology. Molecular markers in combinations with cytogenetics have improved the risk stratification of acute myeloid leukemia (AML) and informed decision-making. In parallel, several important advances in the transplant field, such as better supportive care, improved transplant technology, increased availability of alternative donors, and reduced-intensity conditioning have improved the safety as well as access of allogeneic hematopoietic cell transplantation (HCT) for a larger number of patients. In this review, the positioning of HCT in the management of patients with AML is evaluated in view of changing risk/benefit ratios associated with both conventional treatments and transplantation, and some of the controversies are addressed in light of emerging data. Increasing data demonstrate outcomes of alternative donor transplantation approaching HLA-identical sibling donors in high-risk AML supporting the inclusion of alternative donors in trials of prospective studies evaluating post remission strategies for high-risk AML. The use of reduced-intensity conditioning has expanded the eligibility of HCT to older patients with AML, and outcome data are encouraging. Continued study of HCT versus alternative therapies is required to optimize patients' outcomes in AML.

Acute myeloid leukemia diagnosis in the 21st century

CONTEXT

Rapid advances in understanding the molecular biology of acute myeloid leukemia are transforming the approach to diagnosis, prognostication, and treatment of these cases.

OBJECTIVE

To briefly review the current state of AML classification with a particular emphasis on the role of molecular studies and their impact on the management of acute myeloid leukemia and other malignancies.

DATA SOURCES

Current literature and experience of the authors.

CONCLUSIONS

While morphology, immunophenotyping, cytogenetics, and clinical history continue to play an important role, an increasing number of molecular tests are now required to properly classify these cases.

Prognostic significance of expression of a single microRNA, miR-181a, in cytogenetically normal acute myeloid leukemia: a Cancer and Leukemia Group B study

PURPOSE

To evaluate the prognostic significance of expression levels of a single microRNA, miR-181a, in the context of established molecular markers in cytogenetically normal acute myeloid leukemia (CN-AML), and to gain insight into the leukemogenic role of miR-181a.

PATIENTS AND METHODS

miR-181a expression was measured in pretreatment marrow using Ohio State University Comprehensive Cancer Center version 3.0 arrays in 187 younger (<60 years) adults with CN-AML. Presence of other molecular prognosticators was assessed centrally. A gene-expression profile associated with miR-181a expression was derived using microarrays and evaluated by Gene-Ontology analysis.

RESULTS

Higher miR-181a expression associated with a higher complete remission (CR) rate (P=.04), longer overall survival (OS; P=.01) and a trend for longer disease-free survival (DFS; P=.09). The impact of miR-181a was most striking in poor molecular risk patients with FLT3-internal tandem duplication (FLT3-ITD) and/or NPM1 wild-type, where higher miR-181a expression associated with a higher CR rate (P=.009), and longer DFS (P<.001) and OS (P<.001). In multivariable analyses, higher miR-181a expression was significantly associated with better outcome, both in the whole patient cohort and in patients with FLT3-ITD and/or NPM1 wild-type. These results were also validated in an independent set of older (≥60 years) patients with CN-AML. A miR-181a-associated gene-expression profile was characterized by enrichment of genes usually involved in innate immunity.

CONCLUSION

To our knowledge, we provide the first evidence that the expression of a single microRNA, miR-181a, is associated with clinical outcome of patients with CN-AML and may refine their molecular risk classification. Targeted treatments that increase endogenous levels of miR-181a might represent novel therapeutic strategies.

The prognostic and functional role of microRNAs in acute myeloid leukemia

Expression of microRNAs, a new class of noncoding RNAs that hybridize to target messenger RNA and regulate their translation into proteins, has been recently demonstrated to be altered in acute myeloid leukemia (AML). Distinctive patterns of increased expression and/or silencing of multiple microRNAs (microRNA signatures) have been associated with specific cytogenetic and molecular subsets of AML. Changes in the expression of several microRNAs altered in AML have been shown to have functional relevance in leukemogenesis, with some microRNAs acting as oncogenes and others as tumor suppressors. Both microRNA signatures and a single microRNA (ie, miR-181a) have been shown to supply prognostic information complementing that gained from cytogenetics, gene mutations, and altered gene expression. Moreover, it has been demonstrated experimentally that antileukemic effects can be achieved by modulating microRNA expression by pharmacologic agents and/or increasing low endogenous levels of microRNAs with tumor suppressor function by synthetic microRNA oligonucleotides, or down-regulating high endogenous levels of leukemogenic microRNAs by antisense oligonucleotides (antagomirs). Therefore, it is reasonable to predict the development of novel microRNA-based therapeutic approaches in AML. We review herein results of current studies analyzing changes of microRNA expression in AML and discuss their potential biologic, diagnostic, and prognostic relevance.

Dose escalation of lenalidomide in relapsed or refractory acute leukemias

PURPOSE

Lenalidomide is effective in myeloma and low-risk myelodysplastic syndromes with deletion 5q. We report results of a phase I dose-escalation trial of lenalidomide in relapsed or refractory acute leukemia.

PATIENTS AND METHODS

Thirty-one adults with acute myeloid leukemia (AML) and four adults with acute lymphoblastic leukemia (ALL) were enrolled. Lenalidomide was given orally at escalating doses of 25 to 75 mg daily on days 1 through 21 of 28-day cycles to determine the dose-limiting toxicity (DLT) and maximum-tolerated dose (MTD), as well as to provide pharmacokinetic and preliminary efficacy data.

RESULTS

Patients had a median age of 63 years (range, 22 to 79 years) and a median of two prior therapies (range, one to four therapies). The DLT was fatigue; 50 mg/d was the MTD. Infectious complications were frequent. Plasma lenalidomide concentration increased proportionally with dose. In AML, five (16%) of 31 patients achieved complete remission (CR); three of three patients with cytogenetic abnormalities achieved cytogenetic CR (none with deletion 5q). Response duration ranged from 5.6 to 14 months. All responses occurred in AML with low presenting WBC count. No patient with ALL responded. Two of four patients who received lenalidomide as initial therapy for AML relapse after allogeneic transplantation achieved durable CR after development of cutaneous graft-versus-host disease, without donor leukocyte infusion.

CONCLUSION

Lenalidomide was safely escalated to 50 mg daily for 21 days, every 4 weeks, and was active with relatively low toxicity in patients with relapsed/refractory AML. Remissions achieved after transplantation suggest a possible immunomodulatory effect of lenalidomide, and results provide enthusiasm for further studies in AML, either alone or in combination with conventional agents or other immunotherapies.

C/EBPα regulated microRNA-34a targets E2F3 during granulopoiesis and is down-regulated in AML with CEBPA mutations

The transcription factor, CCAAT enhancer binding protein alpha (C/EBPα), is crucial for granulopoiesis and is deregulated by various mechanisms in acute myeloid leukemia (AML). Mutations in the CEBPA gene are reported in 10% of human patients with AML. Even though the C/EBPα mutants are known to display distinct biologic function during leukemogenesis, the molecular basis for this subtype of AML remains elusive. We have recently showed the significance of deregulation of C/EBPα-regulated microRNA (miR) in AML. In this study, we report that miR-34a is a novel target of C/EBPα in granulopoiesis. During granulopoiesis, miR-34a targets E2F3 and blocks myeloid cell proliferation. Analysis of AML samples with CEBPA mutations revealed a lower expression of miR-34a and elevated levels of E2F3 as well as E2F1, a transcriptional target of E2F3. Manipulation of miR-34a reprograms granulocytic differentiation of AML blast cells with CEBPA mutations. These results define miR-34a as a novel therapeutic target in AML with CEBPA mutations.

BAALC and ERG expression levels are associated with outcome and distinct gene and microRNA expression profiles in older patients with de novo cytogenetically normal acute myeloid leukemia: a Cancer and Leukemia Group B study

BAALC and ERG expression levels are prognostic markers in younger (< 60 years) cytogenetically normal acute myeloid leukemia (CN-AML) adults; their prognostic impact in older (≥ 60 years) patients requires further investigation. We evaluated pretreatment expression of BAALC and ERG in 158 de novo patients treated on cytarabine/daunorubicin-based protocols. The patients were also characterized for other established molecular prognosticators. Low BAALC and ERG expression levels were associated with better outcome in univariable and multivariable analyses. Expression levels of both BAALC and ERG were the only factors significantly associated with overall survival upon multivariable analysis. To gain biological insights, we derived gene expression signatures associated with BAALC and ERG expression in older CN-AML patients. Furthermore, we derived the first microRNA expression signatures associated with the expression of these 2 genes. In low BAALC expressers, genes associated with undifferentiated hematopoietic precursors and unfavorable outcome predictors were down-regulated, whereas HOX genes and HOX-gene-embedded microRNAs were up-regulated. Low ERG expressers presented with down-regulation of genes involved in the DNA-methylation machinery, and up-regulation of miR-148a, which targets DNMT3B. We conclude that in older CN-AML patients, low BAALC and ERG expression associates with better outcome and distinct gene and microRNA expression signatures that could aid in identifying new targets and novel therapeutic strategies for older patients.