Higher G Research Articles

High BAALC expression associates with other molecular prognostic markers, poor outcome, and a distinct gene-expression signature in cytogenetically normal patients younger than 60 years with acute myeloid leukemia: a Cancer and Leukemia Group B (CALGB) study

AbstractBAALC expression is considered an independent prognostic factor in cytogenetically normal acute myeloid leukemia (CN-AML), but has yet to be investigated together with multiple other established prognostic molecular markers in CN-AML. We analyzed BAALC expression in 172 primary CN-AML patients younger than 60 years of age, treated similarly on CALGB protocols. High BAALC expression was associated with FLT3-ITD (P = .04), wild-type NPM1 (P < .001), mutated CEBPA (P = .003), MLL-PTD (P = .009), absent FLT3-TKD (P = .005), and high ERG expression (P = .05). In multivariable analysis, high BAALC expression independently predicted lower complete remission rates (P = .04) when adjusting for ERG expression and age, and shorter survival (P = .04) when adjusting for FLT3-ITD, NPM1, CEBPA, and white blood cell count. A gene-expression signature of 312 probe sets differentiating high from low BAALC expressers was identified. High BAALC expression was associated with overexpression of genes involved in drug resistance (MDR1) and stem cell markers (CD133, CD34, KIT). Global microRNA-expression analysis did not reveal significant differences between BAALC expression groups. However, an analysis of microRNAs that putatively target BAALC revealed a potentially interesting inverse association between expression of miR-148a and BAALC. We conclude that high BAALC expression is an independent adverse prognostic factor and is associated with a specific gene-expression profile.

Wilms Tumor 1 (WT1) Gene Mutations Predict Poor Outcome in Adults with Cytogenetically Normal (CN) Acute Myeloid Leukemia (AML): A Cancer and Leukemia Group B (CALGB) Study.

The WT1 gene on chromosome 11p13 encodes a zinc-finger protein regulating gene transcription. A recent study conducted on 70 CN-AML patients (pts) found that 7 (10%) harbored WT1 mutations (WT1mut) and suggested that WT1mut are associated with failure to achieve complete remission (CR) (Summers et al., Leukemia 2007; 21:550). However, the prognostic impact of WT1mut remains to be elucidated in a larger set of homogeneously treated adults with de novo CN-AML and in the context of established prognostic molecular markers. We studied the prevalence and prognostic impact of WT1mut in 196 younger [<60 years (yrs)] adults with de novo CN-AML who were intensively treated on frontline CALGB protocols incorporating autologous stem cell transplantation for consolidation, i.e. 9621 or 19808. The median follow-up for pts alive was 4.2 yrs (range, 1.2–8.9 yrs). Diagnostic bone marrow and/or blood specimens were studied for WT1mut by denaturing high-performance liquid chromatography and DNA direct sequencing. The samples were also analyzed for FLT3-ITD, FLT3-TKD, MLL-PTD, NPM1 and CEBPA mutations, and ERG and BAALC expression levels. Twenty-one (11%) of the 196 pts had WT1mut [15 had WT1mut in exon 7 (WT1mut7), 5 WT1mut in exon 9 (WT1mut9) and 1 WT1mut in both exons]. WT1mut7 were frameshift or nonsense mutations predicted to result in a truncated WT1 protein; WT1mut9 were missense mutations leading to single amino-acid substitutions. At diagnosis, WT1mut pts had higher white blood cell counts (WBC; P=0.01), more frequently harbored FLT3-ITD (P=0.06) and were more often high ERG (P=0.01) and high BAALC (P=0.006) expressers than unmutated WT1 (WT1wt) pts. While CR rates were not significantly different between WT1mut and WT1wt pts (76% vs 84%, P=0.36), WT1mut pts had worse disease-free survival [(DFS); P<0.001; 3-yr DFS rates, 13% vs 50%; Figure A] and worse overall survival [(OS); P<0.001; 3-yr OS rates, 10% vs 56%; Figure B] than WT1wt pts. In a multivariable analysis, WT1mut independently predicted worse DFS (P=0.009) when controlling for CEBPA (CEBPAmut vs CEBPAwt, P=0.005) and FLT3-ITD/NPM1 risk status (FLT3-ITD-negative and NPM1mut vs all other combinations of FLT3-ITD and NPM1 mutation status, P<0.001). The risk of relapse was 2.9 times higher for WT1mut pts than for WT1wt pts (95% CI: 1.3–6.3). WT1mut also independently predicted worse OS (P<0.001), and conferred a 3.6 times higher risk of death compared with WT1wt pts (95% CI: 1.8–7.2), when controlling for CEBPA (P=0.02), FLT3-ITD/NPM1 risk status (P<0.001), and WBC (P=0.01). In conclusion, we show here for the first time, in a relatively large set of intensively treated younger CN-AML pts, that WT1mut independently predicts very poor outcome. We propose that in future trials, WT1mut analysis should be considered for molecularly-based risk assessment and risk-adapted treatment stratification of CN-AML pts. [Display omitted]

Differential Expression of ERG Isoforms in Acute Myeloid and T-Lymphoblastic Leukemia Is Regulated by DNA-Methylation.

The oncogenic ETS transcription factor ERG is involved in various cellular pathways including developmental regulation, proliferation, and differentiation. In hematopoiesis ERG plays a specific role during normal T-cell differentiation showing high expression levels in stem cells and down regulation in the progenitor compartment. In this regard, it is intriguing that aberrant expression of ERG was found in a subset of patients with acute T-lymphoblastic leukemia (T-ALL) and was associated with an inferior outcome. Furthermore, high level ERG expression was of adverse prognostic significance in patients with newly diagnosed acute myeloid leukemia (AML), thus highlighting ERG's potential role in myeloid as well as T-lineage leukemogenesis. ERG3 (NM_182918) and ERG2 (NM_004449) represent the main isoforms and show abundant expression in myeloid and lymphoid hematopoietic progenitor cells. The expression pattern of specific ERG isoforms in acute leukemias has yet to be investigated. To further elucidate the nature of aberrant ERG expression we have determined the existence and transcriptional regulation of ERG isoforms in pretreatment bone marrow samples of adult T-ALL (n=21) and AML (n=20) patients as well as in normal CD34+ hematopoietic cells of healthy volunteers (n=5). 5′RACE revealed the presence of a new ERG isoform (ERG3Δex12) characterized by expression of exon 5 and absence of exon 12. Expression of ERG3Δex12 was verified by RT-PCR in AML, T-ALL, and CD34+ cells. In addition, real-time RT-PCR showed concomitant expression of the two main isoforms ERG2 and ERG3 in AML and normal CD34+ cells. In contrast, T-ALL patients lacked expression of ERG isoforms harboring exon 4 (ERG2). Promoter analyses of ERG2 and ERG3 revealed the presence of two CpG islands in the ERG2 promoter region, whereas no CpG island was predicted in the ERG3 promoter. Bisulfit conversion of genomic DNA and sequencing of cloned PCR products revealed a significantly higher degree of methylation of CpG island 2 in T-ALL samples (median: 86.4%, range: 16.0 – 98.8%) as compared to AML (median: 38.1%, range: 10.9 – 60.7%; P-value=0.0002 - two sided T-test). As for CpG island 1, CD34+ cells had the lowest rate of methylation in CpG island 2 (median: 7.7%, range: 2.4 – 20.7%). Thus, the differential expression of ERG isoforms is mediated by epigenetic silencing of exon 4 containing transcripts in T-ALL. In conclusion, the identification of the new ERG isoform (ERG3Δex12) suggests the association with different partners as the central exons, including exon 12, guide the interaction with different proteins. Furthermore, the distinct expression of specific ERG transcripts controlled by methylation adds to the complexity of ERG directed downstream pathways in different leukemic subtypes.

Identification of a new subgroup of adult acute T-lymphoblastic leukemia (T-ALL) with a very favorable outcome using low ERG and BAALC expression

7014 Background: High expression of the oncogenic ETS transcription factor ERG is an independent adverse prognostic factor in T-ALL and acute myeloid leukemia (AML). The gene BAALC similarly shows high expression in hematopoietic progenitors, downregulation with onset of differentiation, and prognostic significance in AML. Therefore, we assessed whether combined expression of ERG and BAALC would better predict outcome in T-ALL. Methods: ERG and BAALC mRNA expression was determined by realtime RT-PCR in pretherapy bone marrow of 152 adults with newly diagnosed T-ALL treated on German ALL protocols (05/93, 06/99). Patients (pts) were designated low (n=76) or high (n=76) ERG expressers based on median ERG expression and as low (n=111) or high (n=37) BAALC grouping the lower quartiles 1–3 vs. quartile 4. HOX11 and HOX11L2 expression was determined and immunophenotyping differentiated 3 T-ALL groups (early, thymic, mature). Results: High BAALC expression correlated with immature T-ALL with a higher frequency of early T-ALL (P&lt;0.0001), CD34 positivity (P&lt;0.0001), co-expression of myeloid markers (CD13 and/or CD33; P=0.03), and high ERG expression (P=0.02). Pts with high BAALC had fewer complete remissions (73% vs. 89%, P=0.03) and a higher relapse rate (67% vs. 32%, P=0.01) than low BAALC pts. Excluding 33 pts that had received stem cell transplantation (SCT), high expression of ERG (P=0.002) and of BAALC (P=0.0004) was associated with inferior relapse-free survival (RFS) and overall survival (OS, ERG: P=0.004; BAALC: P=0.0001) compared to low expression of ERG and BAALC, respectively. In contrast, pts with low expression of both ERG and BAALC had the most favorable outcome (5y-RFS: low ERG/low BAALC 81% vs. high ERG and/or high BAALC 33%, P&lt;0.0001; 5y-OS: low ERG/low BAALC 69% vs. high ERG and/or high BAALC 26%, P=0.0001). On multivariable analysis low ERG/low BAALC expression was of independent favorable prognostic significance (RFS, HR: 0.18, P=0.0003; OS, HR: 0.3, P=0.001); the only other prognostic factor was the immunophenotype. Conclusions: Low expression of both ERG and BAALC identifies T-ALL pts with a distinctly favorable long term outcome, thus detecting pts that may not benefit from further treatment intensification including SCT. No significant financial relationships to disclose.

MicroRNA (miR) expression signatures in molecular subsets of cytogenetically normal (CN) acute myeloid leukemia (AML): A Cancer and Leukemia Group B (CALGB) study

7010 Background: Aberrantly expressed miRs contribute to malignant transformation by hybridizing to specific mRNA targets and suppressing their translation into proteins. In CN AML, the largest cytogenetic AML subset, several molecular markers are associated with favorable [e.g., NPM1 mutation (mutNPM1)] or unfavorable [e.g., FLT3 internal tandem duplication (ITD) or high ERG expression (↑ERG)] outcome. We explored if differentially expressed miRs are associated with the aforementioned markers. If so, this might indicate a role for miRs in leukemogenesis and prognosis in CN AML. Methods: Diagnostic samples from 100 adults &lt;60 years, treated on CALGB 19808 (Blood 2005; 106:122a), were analyzed on miR microarrays. Among 305 miR probes, we identified differentially expressed miRs (P&lt;0.005) when comparing patients (pts) with or without mutNPM1, FLT3 ITD or ↑ERG. Results: Nine miRs were differentially expressed in FLT3 ITD compared with FLT3 wild-type pts. miR 155, previously reported in aggressive cancers, was upregulated in FLT3 ITD pts. Strong signatures were associated with mutNPM1 (42 miR probes) and ↑ERG groups (54 miR probes). Consistent with their better prognosis, pts with mutNPM1 had upregulated miRs 10 and 196 targeting HOX genes, miRs 15 and 16 targeting BCL2 and let-7 targeting RAS. Consistent with a more aggressive phenotype, ↑ERG pts had downregulation of let-7 and miR 15 and 16 but also miRs 30, 103, and 24 which target, respectively, CDK6, FBXW11 and MAPK14, all involved in cell cycle regulation and proliferation. Four miRs were associated with event free survival (EFS); all were also associated with ↑ERG. High expression of miRs 124, 129, and 194 was significantly associated with worse EFS and ↑ERG. Low expression of miR 181 was associated with worse EFS and ↑ERG. Notably, downregulation of mir 181 has also been reported in pts with aggressive B-cell chronic lymphocytic leukemia. Conclusions: We report the first miR expression signatures within molecular subsets of CN AML. Further study is warranted to elucidate mechanisms by which miRs contribute to leukemogenesis and impact prognosis, and to determine whether miRs can be therapeutically targeted. No significant financial relationships to disclose.

High Expression Levels of the ETS-Related Gene, ERG, Predict Adverse Outcome and Improve Molecular Risk-Based Classification of Cytogenetically Normal Acute Myeloid Leukemia: A Cancer and Leukemia Group B Study

To validate ERG overexpression as an adverse predictor and assess its prognostic value in the context of other molecular markers in cytogenetically normal (CN) -acute myeloid leukemia (AML). Seventy-six adult patients with primary CN-AML, younger than 60 years and treated on Cancer and Leukemia Group B (CALGB) trial 19808, were evaluated for ERG expression by quantitative reverse transcriptase polymerase chain reaction. They were then combined with 72 patients enrolled onto CALGB 9621 for analyses that included other molecular markers. Similar to patients enrolled onto CALGB 9621, high ERG expressers on CALGB 19808 had fewer complete remissions (CRs; P = .03) and worse event-free survival (EFS; P = .016) than low ERG expressers. In the combined set, high expressers (n = 55) had fewer CRs (P = .004) and shorter EFS (P < .001) than low expressers (n = 93). High ERG predicted failure to achieve CR (P = .004) after adjusting for BAALC expression (P = .04) and age (P = .008), and EFS (P = .004) after adjusting for FLT3 internal tandem duplication (ITD; P < .001). Among patients without FLT3-ITD (FLT3-ITD negative), only high ERG predicted shorter EFS (P = .001). Among NPM1-mutated (NPM1 positive) patients, high ERG predicted shorter EFS (P = .003), after adjusting for FLT3-ITD (P < .001). When all three markers were considered together, in the favorable FLT3-ITD-negative/NPM1-positive subset, high ERG was the only factor predicting shorter EFS (P = .002). We validated ERG overexpression as an adverse predictor in CN-AML. Moreover, by using ERG expression levels, we improved the previously proposed molecular-risk classification of CN-AML based on the presence or absence of FLT3-ITD and NPM1 mutations, given that we identified subsets with different outcome among FLT3-ITD-negative, NPM1-positive, and FLT3-ITD-negative/NPM1-positive patients.

The Identification of ERG Related Pathways Pinpoints to Mechanisms Implicated in the Inferior Outcome of Acute T-Lymphoblastic Leukemia (T-ALL) with High ERG Expression.

The ETS transcription factor ERG is expressed during early, normal T-cell development and shut off once T-cell commitment is complete. In addition, ERG is involved in various chromosomal translocations and implicated in oncogenic pathways in Ewing sarcoma, prostate cancer, and acute myeloid leukemia. Due to the specific regulation during T-cell development and its oncogenic potential we investigated the prognostic impact of ERG expression in T-lymphoblastic leukemia (T-ALL). We have shown in a cohort of 105 adult patients (pts) with newly diagnosed T-ALL that high ERG expression is an independent risk factor predicting inferior relapse-free survival (RFS, P=0.003; 5-year RFS: high ERG 34% vs. low ERG 72%; Baldus et al., JCO. Vol. 24 10/2006). Gene expression profiling (Affymetrix U133 plus 2.0) was performed on diagnostic bone marrow samples of 31 adult T-ALL pts to define an ERG related gene expression signature indicative of its pathogenic role in T-ALL. ERG mRNA expression levels were determined by quantitative real-time RT-PCR and pts were dichotomized at ERG′s median expression level into low ERG (n=16) and high ERG expressers (n=15). After a filtering step that reduced the number of probe sets to just over 10,000, we identified 39 probe sets (representing 35 known genes) differentially expressed (P<0.001) between low ERG and high ERG expressers. Compared to the low ERG group, 23 probe sets had significantly higher expression levels in the high ERG group, and 16 probe sets had significantly lower expression levels in the high ERG group. This signature contained three probe sets for ERG, each one showing about a 2-fold higher expression in the high ERG group as compared to the low ERG group; supporting our RT-PCR results. Of the overexpressed genes in the high ERG group, 5 genes were involved in DNA binding (MYO18A, DNAJC1) or transcription factor activity (ERG, ETV6, DIP). ERG and ETV6 are both ETS transcription factors and are frequently rearranged resulting in oncogenic fusion genes involved in leukemia. Moreover, ETV6 has been shown to be essential for the establishment of early hematopoiesis. In addition, genes with ATPase and ATP binding activity (ATP2B4, ATP2C1, MYO18A), potentially involved in signal transduction pathways were related to high ERG expression. Up-regulation of AKR1C1, a member of the aldo-keto reductase superfamily, was demonstrated in the high ERG group. Interestingly, overexpression of AKR1C1 has been found in various types of cancers and was correlated with tumor progression and resistance to chemotherapy. In conclusion, an ERG associated gene expression signature was identified in T-ALL and provides insights into ERG co-regulated genes. The delineation of these ERG related pathways may pinpoint mechanisms responsible for the more malignant phenotype resulting in the inferior outcome of T-ALL with high ERG expression.

TMPRSS2 Fusions with Oncogenic ETS Factors in Prostate Cancer Involve Unbalanced Genomic Rearrangements and Are Associated with HDAC1 and Epigenetic Reprogramming

Translocations fusing the strong androgen-responsive gene, TMPRSS2, with ERG or other oncogenic ETS factors may facilitate prostate cancer development. Here, we studied 18 advanced prostate cancers for ETS factor alterations, using reverse transcription-PCR and DNA and RNA array technologies, and identified putative ERG downstream gene targets from the microarray data of 410 prostate samples. Out of the 27 ETS factors, ERG was most frequently overexpressed. Seven cases showed TMPRSS2:ERG gene fusions, whereas the TMPRSS2:ETV4 fusion was seen in one case. In five out of six tumors with high ERG expression, array-CGH analysis revealed interstitial 2.8 Mb deletions between the TMPRSS2 and ERG loci, or smaller, unbalanced rearrangements. In silico analysis of the ERG gene coexpression patterns revealed an association with high expression of the histone deacetylase 1 gene, and low expression of its target genes. Furthermore, we observed increased expression of WNT-associated pathways and down-regulation of tumor necrosis factor and cell death pathways. In summary, our data indicate that the TMPRSS2:ERG translocation is common in advanced prostate cancer and occurs by virtue of unbalanced genomic rearrangements. Activation of ERG by fusion with TMPRSS2 may lead to epigenetic reprogramming, WNT signaling, and down-regulation of cell death pathways, implicating ERG in several hallmarks of cancer with potential therapeutic importance.

High Expression of the ETS Transcription Factor ERG Predicts Adverse Outcome in Acute T-Lymphoblastic Leukemia in Adults

In adult T-lymphoblastic leukemia (T-ALL) disease-free survival remains limited to 32% to 46%. The adverse prognosis in T-ALL has not been attributed to cytogenetic or molecular aberrations. We have determined the prognostic impact of the oncogenic transcription factor ERG in T-ALL. ERG expression was analyzed by real-time polymerase chain reaction (PCR) in 105 adults with newly diagnosed T-ALL treated on the German ALL protocols. Patients were dichotomized at ERG's median expression into low (n = 52) and high (n = 53) expressers. Homeobox (HOX) 11 and HOX11L2 expression was determined by real-time PCR. High ERG expressers compared with low ERG expressers had an inferior overall survival (OS, P = .02; 5-year OS: high ERG 26% v low ERG 58%) and relapse-free survival (RFS, P = .003; 5-year RFS: high ERG 34% v low ERG 72%). On multivariable analysis high ERG expression (P = .005), immunophenotypic subgroups (early v mature v thymic T-ALL; overall P = .04), HOX11L2 positivity (P = .055), and absence of HOX11 (P = .017) were independent adverse risk factors predicting RFS. Patients with high ERG expression had a hazard ratio (HR) for relapse of 3.2. Within the good prognostic subgroup of thymic T-ALL (n = 57), high ERG (HR, 4.1; P = .02) and presence of HOX11L2 (HR, 6.6; P = .008) were independent adverse factors for RFS. High expression of ERG is an adverse risk factor in adult T-ALL. Within thymic T-ALL, otherwise classified as standard-risk, high ERG expression-identified patients that were four times more likely to fail long-term RFS. The prognostic impact of ERG may assist treatment stratification and suggest the need of alternative regimens.

High expression of the transcription factor ERG predicts unfavorable outcome in acute T-lymphoblastic leukemia (T-ALL) in adults

6505 Background: In adult T-ALL long-term survival remains limited to 32–46%. Transcription factors are frequently targeted by chromosomal translocations resulting in disruption of hematopoietic proliferation and differentiation. The oncogenic ETS transcription factor ERG is expressed during early T-cell development and shut off once T-cell commitment is complete. We hypothesized that due to its specific involvement in T-cell maturation and oncogenic potential, ERG might contribute to leukemogenesis. Thus we have determined the prognostic impact of ERG expression in T-ALL. Patients and Methods: ERG mRNA expression was analyzed by real-time RT-PCR in pretreatment marrow samples of 105 adults with T-ALL treated on German ALL protocols. Patients (pts) were dichotomized at ERG’s median expression into low (n=52) and high (n=53) expressers. HOX11 and HOX11L2 expression was determined by real-time RT-PCR. Immunophenotyping was performed differentiating T-ALL into 3 subtypes: pre-T (CD2-), thymic (CD1a+), and mature (sCD3+). Results: High ERG expression was associated with a higher relapse rate (45%) compared to pts with low ERG expression (20%; P=0.01). High ERG expressers compared to low ERG expressers had an inferior overall survival (OS, P=0.02; 5-year OS: high ERG 26% vs low ERG 58%) and relapse-free survival (RFS, P=0.003; 5-year RFS: high ERG 34% vs low ERG 72%). On multivariable analysis high ERG expression (P=0.005), immunophenotypic subgroups (pre-T vs mature vs thymic; overall P=0.04), HOX11L2 positivity (P=0.055) and absence of HOX11 expression (P=0.017) were independent adverse risk factors predicting RFS. Patients with high ERG expression had a hazard ratio (HR) for relapse of 3.2. Within the good prognostic subgroup of thymic T-ALL (n=57) high ERG (HR 4.1; P=0.02) and presence of HOX11L2 (HR 6.6; P=0.008) were independent adverse factors for RFS. Conclusion: High expression of the oncogene ERG is an adverse factor in adult T-ALL. Within thymic T-ALL otherwise classified as standard risk, high ERG expression identified pts that were more than four times likely to fail long-term RFS. The prognostic impact of ERG may assist treatment stratification and suggest the need of more intensive regimens for these high risk thymic T-ALL pts. No significant financial relationships to disclose.

Overexpression of the ERG Gene Is an Adverse Prognostic Factor in Acute Myeloid Leukemia (AML) with Normal Cytogenetics (NC): A Cancer and Leukemia Group B Study (CALGB).

Around 45% of adults with AML have NC and are included in an intermediate-risk group. However, their 5-year (yr) overall survival (OS) rates vary between 24 and 42%, likely due to the prognostic impact of submicroscopic genetic alterations, e.g., mutations in FLT3, CEBPA, MLL and NPM genes and overexpression of BAALC. We recently showed that ERG, an ETS-Related Gene mapped to 21q22, is often overexpressed in AML with unfavorable complex karyotypes, and in a subset of NC AML (PNAS 2004; 101:3915), suggesting that ERG overexpression contributes to an aggressive phenotype in AML. Here we analyzed ERG expression levels by real-time RT-PCR in pretreatment blood from 84 adults with NC AML, aged <60 yrs, treated on CALGB 9621 and characterized for BAALC expression (Blood 2003; 102:1613). Patients (pts) were divided into quartiles according to ERG levels and dichotomized into 2 groups: the uppermost quartile of ERG expression values (Q4) and a group comprising 3 lower quartiles (Q1-3), as relapse risk was significantly different for Q4 compared with Q1 (P=.024), Q2 (P=.002) and Q3 (P=.009). The complete remission rates were similar for the 2 groups (76% vs. 83%; P=.532). With a median follow-up of 5.7 yrs, Q4 pts had a worse cumulative incidence of relapse (CIR; P<.001) and OS (P=.011) than Q1-3 pts. For Q4 pts, the estimated 5-yr CIR and OS rates were, respectively, 81% and 19% compared with 33% and 51% for Q1-3 pts. In multivariable models, high ERG expression (Q4) adversely impacted CIR (P<.001), whereas an interaction between ERG and BAALC expression (P=.013) was observed for OS, where Q4 predicted shorter survival only in low BAALC expressers (P=.002; Table 1).Table 1Multivariable analysis for pts divided into Q4 and Q1-3 groups according to ERG expressionEndpointVariableHazard ratio (95% CI)PCIRERG expression (Q4 vs. Q1-3)3.71 (1.88 to 7.31)<.001Present vs. absent MLL PTD2.70 (1.12 to 6.52).027OSInteraction ERG of and BAALC.013 - Pts with low BAALC expression, ERG expression (Q4 vs. Q1-3)5.40 (1.87 to 15.64).002 - Pts with high BAALC expression, ERG expression (Q4 vs. Q1-3)1.04 (0.50 to 2.16).922Log[WBC]1.35 (1.07 to 1.70).012When ERG expression was evaluated in the context of pts with known FLT3 internal tandem duplication (ITD) status, including those with the very unfavorable FLT3ITD/-genotype, i.e., lacking the FLT3 wild-type allele, a multivariable analysis showed that higher risk of relapse and death was independently predicted by both high ERG expression values (i.e., Q4) (P=.023 and P=.002, respectively) and FLT3 ITD mutations (P≤ .001 and P=.002, respectively). We also used Affymetrix U133 plus 2.0 GeneChips to identify genes differentially expressed (P≤ .001) between Q4 and Q1-3 pts. Q4 pts displayed a signature characterized by overexpression of 63 genes and 49 expressed-sequenced tags. Fourteen genes, including general (GTF2H2) and lineage-specific (BCL11A, HEMGN) transcription regulators and genes involved in cell proliferation (RAB10, GAS5) and apoptosis (IKIP, DAPK), had at least a two-fold difference in expression levels between the Q4 and Q1-3 groups. In conclusion, we show for the first time that ERG overexpression in NC AML constitutes an adverse prognostic factor and is associated with a distinct gene-expression signature.