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Background: Non-coding RNAs (ncRNAs) have recently emerged as key regulators of diverse cellular processes, including leukemia. ncRNAs are classified according to their size as short (eg, microRNAs) or long ncRNAs. lincRNAs are long ncRNAs located in intergenic regions and have multiple regulatory functions, including gene expression regulation. Interestingly, active crosstalk between microRNAs and lincRNAs has been observed. lincRNAs are known to be deregulated in some cancers but their importance in acute myeloid leukemia (AML) is so far unknown. HOX genes play an important role in hematopoiesis and are deregulated in AML. lincRNAs are especially abundant in the clusters of HOX genes. HOTAIRM1, a myeloid lineage-specific lincRNA, is located at the 3’end of the HOXA cluster and seems to play a regulatory role in myelopoiesis. However, to date the potential prognostic role of HOTAIRM1 expression in AML has not been examined. Aims: To investigate first whether the expression of the lincRNA HOTAIRM1 is associated with the clinical, cytogenetic and molecular characteristics and microRNA expression in AML patients. Secondly, since intermediate risk (IR) AML patients have a highly diverse prognosis, we analyzed the potential prognostic value of HOTAIRM1 expression in IR-AML patients. Methods: To explore the expression level of HOTAIRM1 among different AML subtypes, we analyzed samples from 244 AML patients including CBF-rearranged AML (n=5), APL (n=4), MLL-rearranged AML (n=3), EVI1-rearranged AML (n=3), t(6;9) AML (n=9), AML with monosomal karyotype (n=3), and a large cohort of IR-AML (described below). For the analysis of prognostic value of HOTAIRM1, we analyzed specifically the outcome of 217 IR-AML patients (median age, 52; 51% males) sequentially included in CETLAM trials during the period 1995-2009. Molecular genotyping of this group identified NPM1 mutation (NPM1mut), FLT3-ITD, and biallelic CEBPA mutation (CEBPA mut) in 99 (45%), 79 (36%) and 17 (11%), respectively. The expression of HOTAIRM1 was analyzed using TaqMan® Gene Expression Assays (Applied Biosystems). microRNA and mRNA expression data were obtained in previous studies (Díaz-Beyá, Leukemia 2013). Statistical analyses were performed with BRB Array Tools, SPSS v20 and R v3.0. MaxStat package from R software was used to determine the optimal cutoff point of HOTAIRM1 expression. Results: Among all 244 patients, HOTAIRM1 expression was significantly different among the 7 included genetic subgroups (ANOVA p=0.0024), with the lowest levels observed in APL-AML patients and the highest in the t(6;9)AML patients. Within the IR-AML group, HOTAIRM1 overexpression was observed in NPM1mut patients (p The prognostic study showed that high HOTAIRM1 expression was associated with shorter 5-year overall survival (OS) (27+11% vs.47+8%; p=0.009) shorter 5-year disease-free survival (LFS) (22+12% vs. 53+9%; p Supervised analysis by means of t-test based on multiple permutations revealed a distinctive 33-microRNA signature which correlated with HOTAIRM1 expression including miR-196b (p Conclusion: The expression level of the lincRNA HOTAIRM1 varied among different molecularly-defined AML. Interestingly, HOTAIRM1 expression level showed independent prognostic value within the IR-AML group. Moreover, HOTAIRM1 expression strongly correlates with its neighboring HOXA4 gene and harbors a distinctive microRNA signature. Our findings can pave the way for further studies of HOX-related lincRNAs and microRNAs regulatory networks and their influence on clinical outcome. Acknowledgments: ISCIII RH13/00205, SEHH, FIS13/00999 Disclosures No relevant conflicts of interest to declare.

Abstract 2524 WT1 monitoring is an almost universal target to follow de novo AML. Its exppression in myeloid malignancies is upregulated in parallel to the blast percentage. Recently, WT1 determination has been standardized as result of an European Leukemia Net initiative. Early reports have demonstrated that the best results are obtained when peripheral blood is used to establish clinical predictions. Pediatric studies in AML have shown that raised WT1 levels after induction associate with unfavourable outcome. Despite all the mentioned, WT1 quantitation has not yet gained widespread use, in part because some AML show normal WT1 levels at diagnosis. To investigate the prognostic impact of the normalized bone marrow WT1 levels at diagnosis and post-induction in a consecutive series of de novo AML patients enrolled in the CETLAM group trials. Available bone marrow samples at diagnosis (586 cases) and post induction (367 cases) were obtained in each participating center and sent to the CETLAM repository center at the Hospital de la Santa Creu i Sant Pau for complete immunophenotype and molecular analyses. One μg of RNA was reverse transcribed to cDNA in a total reaction volume of 20μl containing Cl2Mg 5mM, 10× Buffer, DTT 10mM, dNTP's 10mM each, random hexamers 15μM, RNAsin 20 units (Promega) and 200 units of MMLV enzyme. WT1 expression levels were determined by real-time quantitative polymerase chain reaction (RQ-PCR) in an ABI PRISM 7700® Genetic Analyzer (Applied Biosystems, Foster City, CA) using the primers and conditions described by the ELN group (Cilloni et al J. Clin. Oncol 2009;27:5195-201). For WT1 copy number titration, the IPSOGEN® (Marseille, France) plasmid was employed. Results were expressed as copies and four normal bone marrow samples were used as test controls. Patients were treated between 2004 and 2011 according to the CETLAM03 protocol. Adults up to 70 years of age received induction chemotherapy with idarubicin, intermediate-dose cytarabine and etoposide, followed by consolidation with mitoxantrone and intermediate-dose ara-C. Subsequently, patients with favourable cytogenetics at diagnosis received one cycle of high-dose cytarabine.G-CSF priming during induction and consolidation was used. Patients with favorable cytogenetics and high leukocyte counts at diagnosis were treated with autologous transplantation instead of high-dose cytarabine. Furthermore, patients with a normal karyotype but an adverse molecular profile (FLT3 mutations or MLL rearrangements) were allocated to the treatment for unfavorable cases; this included allogeneic transplantation from an HLA-identical donor. Overall survival (OS) was measured from the date of enrolment until the date of death. Leukemia-free survival (LFS) for patients who achieved a CR was calculated from the date of CR to relapse or death. OS and LFS were plotted by the Kaplan-Meier method; differences between curves were analyzed by the log-rank test. The probability of relapse was calculated using cumulative incidence estimates and taking into account the competing risk of death in remission. A WT1 cut-off value of 5065.2 copies at diagnosis was obtained. Two hundred and four samples had WT1 levels greater than this value, whereas 382 samples showed levels below this cut-off. These groups had statistically different OS 55±3 vs 33±5 p As regards the post-induction results, four groups were established: Group 0 (135 patients) with WT1 levels between 0 and 17.5 copies, Group 1 (107 patients) with WT1 values ranging from 17.6 to 76 copies, Group 2 (54 patients) with WT1 between 76.1 and 170.5 copies and Group 3 (71 patients) with WT1 levels after induction greater than>170.6 copies. These groups showed statistically significant differences(p WT1 quantitation at diagnosis and post-induction provide a simple and well standardized measurement of the prognostic risk of adult AML patiens. Larger series need to be analyzed to ascertain whether this determination could be incorporated to initial AML risk stratification. Disclosures: No relevant conflicts of interest to declare.

Abstract 1452 Introduction: Acute myeloid leukemia (AML) is a heterogeneous group of neoplastic disorders characterized by the presence of acquired genetic alterations in hematopoietic progenitor and stem cells. The prognostic impact of immunophenotypic markers has long been controversial. Despite this, only a very limited number of studies have investigated the prognostic impact of the levels of cell surface membrane (Sm) proteins commonly expressed on AML blasts. In this study we analyzed the prognostic impact of the levels of expression of several markers associated with AML blasts and normal hematopoietic precursors, as asessed by Multiparameter Flow Cytometry (MFC) in de novo AML patients (pts). Methods: Overall, 122 adult de novo AML pts diagnosed between 12/2003 and 08/2011 were studied, after excluding acute promyelocytic leukemia. All cases were diagnosed and classified according to the WHO criteria and they were immunophenotyped using an extensive 4-color panel of monoclonal antibodies by MFC, as previously described. Patients were treated according to the multicenter CETLAM AML-03 trial. Blast cells were gated after excluding all other cell populations, as well-delineated clusters of SSC low/int/CD45dimevents (“blast gate”) using the merge function of the Infinicyt software (Cytognos SL, Salamanca, Spain). For each case, the reactivity for the following markers was evaluated in terms of mean fluorescence intensity (MFI; arbitrary units) in bone marrow samples: CD123, CD117, CD34 and CD7. Normal residual bone marrow lymphocytes were used as reference for internal quality control purposes. Cytogenetic and molecular risk stratifications were based on the European LeukemiaNet (ELN) recommendations and the molecular lesions were investigated using well established protocols. Overall survival (OS), disease-free survival (DFS) and relapse rate (RR) were measured by the Kaplan–Meier method and curves were compared with the log-rank test. Multivariate analysis was performed using the Cox regression model. P-values ≤0.05 were considered to be statistically significant. Results: Median AML patient age was of 54 years (range: 20–70 y) with a M/F ratio of 63/59. Twelve pts (10%) had good cytogenetic/molecular risk, 83 (68%) intermediate, 17 (14%) high risk and 10 (8%) pts were unknown. Fifteen cases (12%) had NPM1mut, 33 (27%) showed FLT3-ITDmut, 5 (4%) pts carried CEBPAmut, 41 (33.6%) pts with no mutations and 28 (23%) pts were unknown. The median follow-up of pts alive was 19 months (range 0–97 months) and the 5-year OS of all pts was 42±5%. Univariate analysis of prognostic factors showed an association between higher CD45 (MFI >232; p=.01), CD117 (MFI>259; p=.008), CD34 (MFI >242; p=.007) and CD7 (MFI> 19; p=.03) expression and both a shorter OS and DFS. In addition, high CD123 expression (MFI >248; p=.04) was associated with a shorter DFS. In multivariate analysis only a high CD45 (p=.03) and a high CD34 (p=.03) expression were identified as independent predictors for a shorter OS. In turn, higher levels of CD123 (p=.03) and of CD34 (p=.02) were independent predictors for DFS and relapse, even when age, gender and WBC were taken in account. Conclusion: In this study, we show that higher levels of expression of immunophenotypic markers associate with immature myeloid precursors (CD45, CD117, CD34 and CD7) as assessed by MFC, have a significantly adverse prognostic impact in AML, both as regards OS and DFS. Accordingly, higher levels of CD45 and CD34 were independent predictors for both a shorter OS whereas, greater CD123 and CD34 values were associated with an increased risk of relapse and a shorter DFS, supporting the adverse prognostic impact of a more immature blast cell phenotype in de novo AML. Disclosures: No relevant conflicts of interest to declare.

Abstract 4813 Accurate cytogenetic and molecular diagnosis of acute myeloid leukemia help to establish the prognosis and to select the best postconsolidation treatments. This genetic characterization is currently being performed by means cytogenetic techniques and molecular methods mainly based in PCR, capillary electrophoresis and Sanger sequencing. Recently, large and homogeneous series of AML patients have been analyzed by means expression arrays. These studies have helped to standardize the method and they are becoming an alternative to traditional methods in terms of simplicity and time. Objectives To assess the usefulness of the AMLprofiler™ in genetic stratification of de novo AML enrolled in a cooperative Group. To investigate the applicability of the array diagnostic platform in multicenter trials. To compare the AMLprofiler™ with the standard approach. Patients and methods Twenty one consecutive de novo AML cases enrolled in the Spanish CETLAM protocol were included in the study. Patients were recruited during 2012. Cytogenetic analysis was performed in each participating center and the results were sent to the HSCSP. Complete immunophenotype and molecular studies were performed centrally at the HSCSP. Purified DNA was employed to test FLT3-ITD and TKD mutations, NPM1, CEBPa and MLL. For each FLT3-ITD positive case, the allelic ratio was calculated. Given that FLT3 mutations are not detected by the AML-profiler™, this determination was common to both approaches. Purified RNA was used to assess the presence of the AML1-ETO and CBFb-MYH11 rearrangements and to test RNA integrity. We used the AMLprofiler™ assay which detects chromosomal aberrations (t(8;21), t(15;17), inv(16), mutations (CEBPA dm, NPM1 A/B/D) and genetic expresion of BAALC and EVI1. Only those cases fulfilling the quality required by the manufacturer were hybridized the AMLprofiler™array. Based on this requirement one case was ruled out. Results Twenty cases were analyzed with the AMLprofiler™ and with the conventional methods (21 intended/20 hybridized). There were 4 cases with FLT3-ITD. One case had a t(8;21) and it has been succesfully detected by both methods. There were 4 inv(16), in one case the RNA quality was not satisfactory and was not hybridized, in the remaining 3 cases the AMLprofiler detected the genetic lesion including one case with a cryptical translocation and in one case with a typical inv(16) but with a complex CBFb-MYH11 transcript. In 8 cases a NPM1 mutation was detected by molecular methods, in all NPM1 A, B or D, the AMLprofiler™ gave concordant results, one case with a non-ABD mutation was not detected. When considering technician times, AMLprofiler™ compared favorably with the conventional molecular biology techniques (mean times: 2958 min vs 3422 min). This figure does not take into consideration the cytogenetic workload performed in each participating center. Conclusions The AMLprofiler™ could be easily used to stratify de novo AML patients enrolled in multicenter trials. It provides accurate results and requiring less time than the currently employed methods in the CETLAM group. The AMLprofiler™ seems to be specially useful in the core binding-factor leukemias. The most important limitations are related to the need of an excellent RNA sample and the presence of rare NPM1 mutations. Disclosures: No relevant conflicts of interest to declare.

Abstract 1712 The study of chromosome alterations helps to classify acute myeloid leukemia (AML) into three prognostic groups, favorable, intermediate and adverse. The prognostic value of favorable risk and adverse risk abnormalities is well defined; in contrast, the outcome of intermediate-risk group is heterogeneous. Molecular characterization of patients with intermediate-risk AML has identified subcategories with diverse prognosis. All this knowledge has translated into a recent ELN proposal for the genetic classification of AML. Additionally, the intermediate and particularly the cytogenetically adverse groups have been refined by the HOVON group by introducing the concept of “monosomal karyotype” (MK), consisting of at least two autosomal monosomies or one monosomy plus a structural abnormality. Objective: To validate the recent ELN classification in a large series of AML patients and to investigate if the inclusion of MK improved the prognostic stratification. Patients and methods: 804 consecutive patients treated under the CETLAM AML-99 (n=353) and CETLAM-03 (n=451) trials were analyzed. The two protocols included idarubicin, intermediate-dose cytarabine and etoposide as induction and mitoxantrone and intermediate-dose cytarabine as consolidation. G-CSF priming was given in the CETLAM-03 trial. Following, risk-adapted treatment with chemotherapy or hematopoietic transplantation was administered. Parameters analyzed were relapse rate (REL), leukemia-free survival (LFS) and overall survival (OS). Results: Median age of the series was 46 years (range 16–60). Median follow-up of patients alive was 15 months. The ELN classification resulted in different prognostic risk groups. At 5 years, ELN favorable risk category had an OS of 60±4%, intermediate-I of 32±%, intermediate-II of 46±% and adverse of 17±3% (p Conclusion: In the present study, the ELN genetic classification did not discriminate the prognosis of patients in the intermediate-I and intermediate-II categories. In contrast, genetic grouping that considered CBF AML, favorable mutations in the intermediate cytogenetics category and that separated adverse karyotype with or without MK translated into significantly different OS. This classification, together with the study of mutations recently described and the expression of certain genes may contribute to a more precise prognostic stratification and risk-adapted therapy. Disclosures: No relevant conflicts of interest to declare.