PURPOSE To analyze the frequency and associations with prognostic markers and outcome of mutations in IDH genes encoding isocitrate dehydrogenases in adult de novo cytogenetically normal acute myeloid leukemia (CN-AML). PATIENTS AND METHODS Diagnostic bone marrow or blood samples from 358 patients were analyzed for IDH1 and IDH2 mutations by DNA polymerase chain reaction amplification/sequencing. FLT3, NPM1, CEBPA, WT1, and MLL mutational analyses and gene- and microRNA-expression profiling were performed centrally. Results IDH mutations were found in 33% of the patients. IDH1 mutations were detected in 49 patients (14%; 47 with R132). IDH2 mutations, previously unreported in AML, were detected in 69 patients (19%; 13 with R172 and 56 with R140). R172 IDH2 mutations were mutually exclusive with all other prognostic mutations analyzed. Younger age (< 60 years), molecular low-risk (NPM1-mutated/FLT3-internal tandem duplication-negative) IDH1-mutated patients had shorter disease-free survival than molecular low-risk IDH1/IDH2-wild-type (wt) patients (P = .046). R172 IDH2-mutated patients had lower complete remission rates than IDH1/IDH2wt patients (P = .007). Distinctive microarray gene- and microRNA-expression profiles accurately predicted R172 IDH2 mutations. The highest expressed gene and microRNAs in R172 IDH2-mutated patients compared with the IDH1/IDH2wt patients were APP (previously associated with complex karyotype AML) and miR-1 and miR-133 (involved in embryonal stem-cell differentiation), respectively. CONCLUSION IDH1 and IDH2 mutations are recurrent in CN-AML and have an unfavorable impact on outcome. The R172 IDH2 mutations, previously unreported in AML, characterize a novel subset of CN-AML patients lacking other prognostic mutations and associate with unique gene- and microRNA-expression profiles that may lead to the discovery of novel, therapeutically targetable leukemogenic mechanisms.

The ELN classification clearly separates the genetic groups by outcome, supporting its use for risk stratification in clinical trials. Because they have different proportions of genetic alterations and outcomes, younger and older patients should be reported separately when using the ELN classification.

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.

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 mutationassociated 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. (Blood. 2011;118(26):6920-6929)

A B S T R A C T PurposeTo analyze the prognostic significance of NPM1 mutations, and the associated gene-and microRNA-expression signatures in older patients with de novo, cytogenetically normal acute myeloid leukemia (CN-AML) treated with intensive chemotherapy. Patients and MethodsOne hundred forty-eight adults age Ն 60 years with de novo CN-AML, enrolled onto Cancer and Leukemia Group B protocols 9720 and 10201, were studied at diagnosis for NPM1, FLT3, CEBPA, and WT1 mutations, and gene-and microRNA-expression profiles. ResultsPatients with NPM1 mutations (56%) had higher complete remission (CR) rates (84% v 48%; P Ͻ .001) and longer disease-free survival (DFS; P ϭ .047; 3-year rates, 23% v 10%) and overall survival (OS; P Ͻ .001; 3-year rates, 35% v 8%) than NPM1 wild-type patients. In multivariable analyses, NPM1 mutations remained independent predictors for higher CR rates (P Ͻ .001) and longer DFS (P ϭ .004) and OS (P Ͻ .001), after adjustment for other prognostic clinical and molecular variables. Unexpectedly, the prognostic impact of NPM1 mutations was mainly observed in patients Ն 70 years. Gene-and microRNA-expression profiles associated with NPM1 mutations were similar across older patient age groups and similar to those in younger (Ͻ 60 years) patients with CN-AML. These profiles were characterized by upregulation of HOX genes and their embedded microRNAs and downregulation of the prognostically adverse MN1, BAALC, and ERG genes. ConclusionNPM1 mutations have favorable prognostic impact in older patients with CN-AML, especially those age Ն 70 years. The gene-and microRNA-expression profiles suggest that NPM1 mutations constitute a marker defining a biologically homogeneous entity in CN-AML that might be treated with specific and/or targeted therapies across age groups.

The clinical impact of FLT3-internal tandem duplications (ITDs), an adverse prognostic marker in adults aged < 60 years with primary cytogenetically normal acute myeloid leukemia (CN-AML), requires further investigation in older patients. In CN-AML patients aged > 60 years treated on Cancer and Leukemia Group B frontline trials, we found that FLT3-ITD remained associated with shorter disease-free survival (P < .001; hazard ratio ‫؍‬ 2.10) and overall survival (P < .001; hazard ratio ‫؍‬ 1.97) in multivariable analyses. This impact on shorter disease-free survival and overall survival was in patients aged 60-69 (P < .001, each) rather than in those aged > 70 years. An

A B S T R A C T PurposeTo 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 MethodsFour 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. ResultsYounger (Ͻ 60 years; n ϭ 181) and older (Ն 60 years; n ϭ 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 ϭ 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 ϭ .03) and, by trend, overall survival (OS; P ϭ .07) than DNMT3A-wild-type patients. In multivariable analyses, DNMT3A mutations remained associated with shorter DFS (P ϭ .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 ϭ .002) and OS (P ϭ .02), whereas older patients with R882-DNMT3A mutations had shorter DFS (P ϭ .005) and OS (P ϭ .002) after adjustment for other clinical and molecular prognosticators. Gene-and microRNAexpression signatures did not accurately predict DNMT3A mutational status. ConclusionDNMT3A 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.

Purpose To evaluate the impact of miR-155 on the outcome of adults with cytogenetically normal (CN) acute myeloid leukemia (AML) in the context of other clinical and molecular prognosticators and to gain insight into the leukemogenic role of this microRNA. Patients and Methods We evaluated 363 patients with primary CN-AML. miR-155 levels were measured in pretreatment marrow and blood by NanoString nCounter assays that quantified the expression of the encoding gene MIR155HG. All molecular prognosticators were assessed centrally. miR-155–associated gene and microRNA expression profiles were derived using microarrays. Results Considering all patients, high miR-155 expression was associated with a lower complete remission (CR) rate (P < .001) and shorter disease-free survival (P = .001) and overall survival (OS; P < .001) after adjusting for age. In multivariable analyses, high miR-155 expression remained an independent predictor for a lower CR rate (P = .007) and shorter OS (P < .001). High miR-155 expressers had approximately 50% reduction in the odds of achieving CR and 60% increase in the risk of death compared with low miR-155 expressers. Although high miR-155 expression was not associated with a distinct microRNA expression profile, it was associated with a gene expression profile enriched for genes involved in cellular mechanisms deregulated in AML (eg, apoptosis, nuclear factor-κB activation, and inflammation), thereby supporting a pivotal and unique role of this microRNA in myeloid leukemogenesis. Conclusion miR-155 expression levels are associated with clinical outcome independently of other strong clinical and molecular predictors. The availability of emerging compounds with antagonistic activity to microRNAs in the clinic provides the opportunity for future therapeutic targeting of miR-155 in AML.