High BAALC Research Articles

Performance evaluation and clinical impact of the Oncomine Myeloid Research Assay for gene expression analysis in myeloid haematologic malignancies

AimGene expression analysis facilitates the detection of diagnostic and prognostic biomarkers for myeloid haematological malignancies. The Oncomine Myeloid Research Assay (OMA; Thermo Fisher Scientific, Massachusetts, USA) provides a comprehensive analysis...

BAALC gene expression tells a serious patient outcome tale in NPM1-wild type/FLT3-ITD negative cytogenetically normal-acute myeloid leukemia in adults

Acute myeloid leukemia with normal cytogenetics (CN-AML) is the largest group of AML patients which is associated with a variegated patient outcome. Multiple molecular markers have been used to risk-stratify these patients. Estimation of expression of BAALC gene (Brain and Acute Leukemia, Cytoplasmic) mRNA level is one of the predictive markers which has been identified in multiple studies. In this study, we examined the clinical and prognostic value of BAALC gene expression in 149 adult CN-AML patients. We also utilized multi-omics databases to ascertain the association of BAALC gene expression with comprehensive molecular and clinicopathologic features in AML. BAALC overexpression was associated with CD34 positivity on leukemic blasts (p = 0.0026) and the absence of NPM1 gene mutation (p < 0.0001), presence of RUNX1 gene mutation (p < 0.001) and poor patient outcomes, particularly in NPM1–wild type/FLT3-ITD negative adult CN-AML patients. Additionally, BAALC expression was associated with the alteration of methylation of its promoter. Further, pathway analysis revealed that BAALC expression is correlated with MYC targets and Ras signalling. We conclude that high BAALC expression associates with poor patient outcome in NPM1–wild type/FLT3-ITD negative adult CN-AML patients.

Physical interaction between BAALC and DBN1 induces chemoresistance in leukemia

BAALC is identified as a leukemia-associated gene and is highly expressed in CD34-positive hematopoietic stem cells. High BAALC expression is associated with poor prognosis in several types of acute myeloid leukemia. We explored binding partner proteins of BAALC by means of mass spectrometry and analyzed biological properties of BAALC-expressing leukemic cells. We found that BAALC physically interacts with DBN1, which is an actin-binding protein and promotes cell adhesion and mobility by forming cell membrane spines during cell-cell interactions. Drebrin1 downregulation impeded cell adhesion to bone marrow stromal cells, resulting in improvement of sensitivity to cytarabine. Taken together, our findings suggest that BAALC-DBN1 interaction contributes to the anchoring of BAALC-expressing cells in the bone marrow, which in turn leads to resistance to cytotoxic drugs. Therefore, the BAALC-DBN1 interaction provides us with an opportunity to overcome the chemotherapy resistance in BAALC-activated leukemia via functional blockage of these genes.

Comprehensive Analysis of Immunophenotype and Transcriptome in Indian T-Acute Lymphoblastic Leukemia - a Prospective Study

T-cell acute lymphoblastic leukemias (T-ALLs) are aggressive hematologic tumors that result from the malignant transformation of T-cell progenitors. T-ALLs are classified immunologically into immature (pro- and pre-T), cortical and mature T-ALL. ETP-ALL is a recently described subtype of immature T-ALL. T-ALL is characterized by overexpression of oncogenic transcription factors that drive the malignancy: TAL1, TAL2, LYL1,LMO1, LMO2; TLX1, TLX3, NKX2.1, NKX2.2, NKX2.5, MEF2C and HOX genes. This study was conducted to understand the landscape of protein-coding genes using RNAseq in immature, cortical and mature T-ALL patients in India. This was a prospective study done on 134 T-ALL cases. The T-ALL patients were divided into 2 cohorts: discovery (n=35; immature 13, cortical 17, mature 5) and validation cohort (n=99; immature 45, cortical 44, mature 10). Total RNA seq was done in the discovery cohort. Clinical and prognostic relevance of lesions identified in the discovery cohort were studied in validation cohort. On RNAseq, a total of 2,318 genes were most differentially expressed between the 3 subtypes. In immature T-ALL cases, transcription factors controlling early hematopoiesis (MEF2C, TP63, HHEX, RUNX2, HOXA10, HOXA9, RUNX1T1 and ZBTB16) were highly expressed. LYN, a tyrosine kinase gene was also highly expressed. BAALC and MN1 genes, previously reported in acute myeloid leukemia, but not emphasized in reported genomics studies in the West, were overexpressed. Interestingly, LMO2 was overexpressed in the absence of significant overexpression of LYL1, a gene reported to be critical for oncogenic functions of Lmo2. In cortical T-ALL, the cortical thymocyte-defining CD1A gene was overexpressed. Homoebox domain genes NKX2-1, TLX1, TLX3, involved in T-cell development were overexpressed. In addition, FAT1, FAT3, EREG, CD1C, AKAP-2, IL-4, PRTG, TCL-6, ZP1 and TRAV genes were overexpressed. On examining CD1a+/sCD3+ and CD1a+/sCD3- groups, we found that in contrast to reported literature, TLX1 was highly expressed in the former group and TLX3 in the latter. In mature T-ALL, APC2, BCL3, CCR4, CDKN2A, EML4, HIST1H4G, HIST2H2B, NCOR2, ST20 and TRAV22 genes were overexpressed. Conventional drivers of T-ALL leukemogenesis - LYL1, TAL1 and LMO1 were not differentially expressed in our patients suggesting a difference between Indian and Western T-ALL patients. The clinical significance of expression of MEF2C, BAALC, HHEX, LYL1, TAL1 and FAT1 genes was studied in validation cohort by real-time PCR. High expression of MEF2C and BAALC gene was associated with immature immunophenotype (IPT) as compared to cortical and mature IPT (p=0.009; 0.008, respectively). Patients with ETP-ALL had higher expression of MEF2C and BAALC gene (p=0.018; 0.014, respectively). High MEF2C and BAALC expression were associated with CD34 positivity (p=0.004; 0.032, respectively). High BAALC expression was also associated with aberrant expression of the myeloid markers (p=0.021). Although not statistically significant, high HHEX expression was associated with immature IPT (p=0.072) and ETP-ALL IPT (p=0.06). Although LYL1 expression did not correlate with immature IPT, ETP-ALL was associated with higher LYL1 expression (p=0.039). Higher expression of FAT1 gene was associated with cortical IPT (p=0.026). Low XIST expression was more frequently associated with non-ETP-ALL IPT (p=0.017). TAL1 expression did not correlate with IPT. On survival analysis, only MEF2C gene expression was associated with EFS and OS. Compared to low MEF2C expressors, patients with high MEF2C had a lower event free survival (EFS) (73.58% vs 51.38%, p=0.01). High expression was found to be a significant predictor of overall survival (OS) (81.11% vs 96.43%, p=0.012). MEF2C emerged as driving oncogene in our T-ALL patients which can be used as predictor of EFS and OS. Expression of BAALC, HHEX, LYL1, TAL1, FAT1 and XIST genes did not correlate with EFS and OS. In this first study correlating T-ALL IPT with transcriptome profile in Indian T-ALL patients, we noted interesting differences from the West, potential subjects of further study. MEF2C gene expression emerged as the predictor of poor EFS and OS in T-ALL patients. Lastly, increased expression of LYN gene in our patients suggests that our immature T-ALL patients may benefit from tyrosine kinase inhibitors targeting Lyn. Disclosures No relevant conflicts of interest to declare.

High BAALC copy numbers in peripheral blood prior to allogeneic transplantation predict early relapse in acute myeloid leukemia patients.

High BAALC expression levels at acute myeloid leukemia diagnosis have been linked to adverse outcomes. Recent data indicate that high BAALC expression levels may also be used as marker for residual disease following acute myeloid leukemia treatment. Allogeneic hematopoietic stem cell transplantation (HSCT) offers a curative treatment for acute myeloid leukemia patients. However, disease recurrence remains a major clinical challenge and identification of high-risk patients prior to HSCT is crucial to improve outcomes. We performed absolute quantification of BAALC copy numbers in peripheral blood prior (median 7 days) to HSCT in complete remission (CR) or CR with incomplete peripheral recovery in 82 acute myeloid leukemia patients using digital droplet PCR (ddPCR) technology. An optimal cut-off of 0.14 BAALC/ABL1 copy numbers was determined and applied to define patients with high or low BAALC/ABL1 copy numbers. High pre-HSCT BAALC/ABL1 copy numbers significantly associated with higher cumulative incidence of relapse and shorter overall survival in univariable and multivariable models. Patients with high pre-HSCT BAALC/ABL1 copy numbers were more likely to experience relapse within 100 days after HSCT. Evaluation of pre-HSCT BAALC/ABL1 copy numbers in peripheral blood by ddPCR represents a feasible and rapid way to identify acute myeloid leukemia patients at high risk of early relapse after HSCT. The prognostic impact was also observed independently of other known clinical, genetic, and molecular prognosticators. In the future, prospective studies should evaluate whether acute myeloid leukemia patients with high pre-HSCT BAALC/ABL1 copy numbers benefit from additional treatment before or early intervention after HSCT.

联合检测中危组成人急性髓系白血病患者MDR1与BAALC基因mRNA表达水平及其临床意义

急性髓系白血病(Acute myeloid leukemia, AML)是高度异质性疾病，存在多种具有不同功能的临床意义的基因或分子学异常。我们已经证明了MDR1、BAALC基因均为AML重要的独立预后指标。但是联合检测这两个指标对于中危组AML预后的意义尚未进行阐述。方法：使用实时定量PCR方法检测105例初治成人中危组AML的骨髓标本中MDR1和BAALC基因mRNA水平。将AML患者根据两个基因表达水平分别分为高表达组和低表达组，并统计分析两组病例中临床预后间差异。结果：105例中危组AML中首次诱导化疗后CR率为79.0% (83/105)，复发率为38.6% (32/83)。根据MDR1和BAALC基因表达情况，将105例患者分为4组。MDR1基因和BAALC基因均高表达组、MDR1基因高表达而BAALC基因低表达组、MDR1基因低表达而BAALC基因高表达组、MDR1基因和BAALC基因均低表达组。前三组间病人的一般情况及预后资料之间无统计学差异，因此将后组合并为一个组，即高MDR1和/或高BAALC基因表达组。低MDR1/低BAALC患者的CR率(91.4% vs 72.9%, P = 0.028)和OS (79.7% vs 25.3%, P = 0.000)明显高于高MDR1和/或高BAALC基因高表达组，而复发率明显低于MDR1和/或BAALC基因高表达组(15.6% vs 52.9%, P = 0.001)。结论：联合检测MDR1和BAALC基因表达有助于提高成人中危组AML的分层级预后判断，低MDR1/低BAALC的AML患者预后较好。 Objective: Acute myeloid leukemia (AML) is a heterogeneous disease, in terms of genetic/mole- cular abnormalities resulting into marked differences in outcome. We had demonstrated that MDR1, BAALC expression were of prognostic significance and high MDR1 expression correlated with a high BAALC expression in intermediate-risk AML in the prophase study. We founded that MDR1 and BAALC expression together would better identify the patient’s risk profile. Methods: Pretreatment bone marrow samples from 105 adult intermediate risk group AML (IR-AML) patients were analyzed for MDR1 and BAALC mRNA expression by real-time reverse transcriptase polymerase chain reaction. Patients were divided into different groups according to MDR1 and BAALC levels and were compared for clinical outcome. Results: 83 cases of 105 IR-AML patients got CR after the first block with a CR rate being 79.0%. However, 32 cases of the CR patients with IR-AML relapsed with the relapsed rate being 38.6%. On the basis of MDR1 and BAALC expression status, we identified four different subgroups: low MDR1/low BAALC (N = 35), low MDR1/high BAALC (N = 17), high MDR1/low BAALC (N = 17), and high MDR1/high BAALC (N = 36). Patients with high expression of MDR1 and/or BAALC were characterized by an inferior outcome with no significant differences between the three groups; thus, these patients were considered a single group. Patients with low MDR1/low BAALC had a superior CR rate (91.4% vs 72.9%, P = 0.028), OS (79.7% vs 25.3%, P = 0.000) and lower relapse rate 15.6% vs 52.9%, P = 0.001) than high MDR1 and/or high BAALC expression in IR-AML. Conclusion: The combined assessment of BAALC and MDR1 expression can improve treatment stratification in adult IR-AML. Low expression of both MDR1 and BAALC identifies IR-AML patients with a favorable long-term outcome.

Feasibility of BAALC gene expression for detection of minimal residual disease and risk stratification in normal karyotype acute myeloid leukaemia.

High BAALC gene expression has been associated with poor prognosis in cytogenetically normal acute myeloid leukaemia (CN-AML) and has been suggested as a suitable marker for assessing minimal residual disease (MRD). The purpose of this study was to substantiate these findings by the analysis of a large data set of 632 diagnostic and follow-up samples in 142 intensively treated CN-AML patients. Paired diagnostic/relapse samples of 35 patients revealed stable high BAALC expression in 89%, irrespective of a high proportion of clonal evolution found in 49% of these cases. High BAALC expression, both directly after induction chemotherapy and within 3-6months after induction chemotherapy, correlated significantly with shorter event-free survival and overall survival. Moreover, 8 of 10 patients displaying high BAALC expression levels after completion of induction therapy as well as 5 of 5 patients exhibiting high BAALC expression levels within 3-6months after induction chemotherapy experienced relapse with a median of 197 and 101days, respectively, from sampling to relapse. Thus, BAALC expression-based MRD detection during therapy may be considered a strategy to identify patients at high risk of relapse.

Unsupervised Cluster Analysis of Antigen Expression Patterns Identifies Subgroups with Distinct Biological and Clinical Features in Patients with Acute Myeloid Leukemia Undergoing Allogeneic Stem Cell Transplantation

Characterisation of antigen expression patterns is part of the standard diagnostic work-up in acute myeloid leukemia (AML). But the biological & clinical implication of such antigen expression patterns have not been studied extensively & remain unclear in AML patients (pts) undergoing allogeneic stem cell transplantation (SCT).We analyzed the diagnostic antigen expression patterns of 162 AML pts (median age 64.7 years [y, range 46.6-76.2y]) with available data who received allogeneic peripheral blood SCT after non-myeloablative conditioning (NMA-SCT) between 2001 & 2013 at our institution. Conditioning regimen was fludarabine 3x30mg/m2 & 2Gy total body irradiation. Donors were human leukocyte antigen (HLA) matched related (12%) or HLA matched (59%) or mismatched unrelated (29%). Mutation (mut) status of the NPM1, CEBPA, IDH1, IDH2 &DNMT3A gene, presence of FLT3 -ITD &FLT3-TKD & the expression status of BAALC, ERG, MN1, EVI1, miR-9 &miR-181a at diagnosis were accessed. Pts were grouped according to the European LeukemiaNet (ELN) genetic classification in 22% favorable (fav), 24% intermediate-I (int-I), 21% intermediate-II (int-II) & 32% adverse (adv). Median follow up was 3.2y. To assess antigen expression patterns at diagnosis for all pts, flow cytometric analysis utilizing a standard panel (CD2, CD7, CD11b, CD13, CD14, CD15, CD33, CD34, CD38, CD45, CD56, CD61, CD64, CD65, CD117 & Glycophorin A) of mononuclear cells in bone marrow (BM) was performed. Using R's gplot package we performed unsupervised hierarchical clustering of the antigen expression which revealed 4 subgroups with distinct antigen expression patterns (Figure 1).At diagnosis, pts grouped in cluster 1 (n=19) had higher white blood count (WBC, P =.004) & lower peripheral blood (PB) blast count (P =.03) & were more likely to have de novo AML (P =.05). They were also less likely to have trisomy 8 (P =.08) by trend & more likely to have normal karyotype (KT, P =.05), to have ELN fav risk (P =.04), to be NPM1 mut (P =.002) & to be DNMT3A mut by trend (P =.08) & had lower miR-181a (P =.04), lower BAALC (P<.001), lower ERG (P =.01) & lower MN1 expression (P<.001).Pts grouped in cluster 2 (n=35) had higher WBC (P<.001), PB blasts (P<.001) & BM blasts (P =.005) at diagnosis. They were less likely to have trisomy 8 (P =.008) & to have deletion (del) 7/7q (P =.07) by trend, were more likely to be NPM1 mut (P =.002) & to have FLT3 -ITD (P <.001) & had lower BAALC (P =.1) & lower EVI1 expression (P =.09) by trend.Pts grouped in cluster 3 (n=59) had lower WBC (P<.001), PB blasts (P<.001) & BM blasts (P<.001) at diagnosis & were less likely to have de novo AML (P<.001). They were more likely to have trisomy 8 (P =.05), del5/5q (P =.004), monosomal KT (P =.04), complex KT (P =.07) by trend & ELN adv risk (P =.04), were less likely to be NPM1 mut (P =.03) &FLT3 -ITD by trend (P =.08) & had lower ERG (P =.008) & higher miR-9 (P =.009) expression.Pts grouped in cluster 4 (n=49) had lower WBC (P =.03), higher PB blasts (P =.007) & BM blasts (P<.001) at diagnosis. They were less likely to have del5/5q (P =.008) &NPM1 mut (P <.001) & had lower miR-9 (P =.007) & higher BAALC (P<.001), ERG (P<.001) &MN1 (P<.001) expression.For the entire set of pts, belonging to one of the antigen expression clusters did not impact on outcome. However, when the ELN groups were regarded separately, within the ELN fav group, cluster 1 pts had a significantly shorter event free survival (EFS, P =.04, Figure 2A) & within the ELN int-I group, cluster 3 pts had a trend for better (P =.096) & cluster 4 pts for worse EFS (P =.087).In conclusion, the antigen expression patterns at diagnosis obtained by unsupervised cluster analysis associated with distinct biological & clinical features (Figure 2B): NPM1 mut were enriched in clusters 1 & 2. Cluster 1 was characterized by ELN fav risk, normal KT, de novo disease & lower BAALC, ERG, MN1 &miR-181a expression. Cluster 2 was characterized by a high incidence of FLT3-ITD. We found more pts with ELN adv risk, monosomal KT, secondary AML & low miR-9 expression in cluster 3 & higher miR-9 as well as lower BAALC, ERG &MN1 expression levels in cluster 4. Even though we did not observe a prognostic impact of the antigen expression patterns in the entire cohort, the patterns may help to refine the ELN risk classification for AML pts undergoing SCT. Assessing the diagnostic antigen expression patterns provides information on disease biology, clinical parameters and potentially disease aggressiveness in AML. [Display omitted] [Display omitted] DisclosuresFranke:BMS: Honoraria; MSD: Other: Travel Costs; Novartis: Other: Travel Costs. Niederwieser:Novartis: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau.

High Prognostic Value of a 3-Genes Molecular Score in Non-High Risk Acute Promyelocytic Leukemia Treated with AIDA 2000 Protocol: A Retrospective Study from a Regional Register

BACKGROUND AND AIMSNon high risk acute promyelocytic leukemia (APL) patients, as defined by WBC count at diagnosis, have nowadays a very good prognosis when treated with ATRA plus chemotherapy based protocols, with high rate of complete molecular remission after consolidation therapy. However, a small proportion of patients (roughly 10-15%) will eventually relapse, despite the achievement of molecular CR.In the past years, some groups showed that relapse risk could be predicted by testing for some gene alterations, such as FLT3-ITD, or by break point cluster region (BCR) analysis. However, those results were not confirmed in prospective trials.We retrospectively applied a simple 3 gene based molecular panel to low-intermediate risk acute promyelocytic patients, alongside with BCR analysis, in order to develop a risk score.MATERIALS AND METHODSFifty-nine low/intermediate risk APL patients, treated with the Italian age-adapted AIDA protocol from January 1st 2004 to December 31st 2014 in our center were retrospectively included in this study. Median age was 47 years (range 19-88), 16 patients were older than 60 years (27%).BCR analysis was available in all patients, 41 patients showed BCR1/2, whereas 18 patients had BCR3 (30%).Molecular profile included determination of FLT3-ITD mutation, WT1 and BAALC gene expression levels and was available in 38/59 patients (64%); bone marrow sample of diagnosis is available for all other 21 patients for further analysis. Cut-off values for WT1 (20000/abl x 104) and BAALC (450/abl x 104) were arbitrarily chosen after pre-analysis and comparison with our published data.Five patients had FLT3-ITD mutation (13%), 18 (45%) patients had higher WT1 expression levels and BAALC was overexpressed in 9 (24%) patients.Pre-analysis showed that FLT3-ITD, low WT1 levels, high BAALC levels but not the presence of BCR3 were associated with higher relapse risk. A molecular score including those 3 genes was built: 16 patients had no risk factors (42%), 17 patients had one risk factor (45%), 5 had two risk factors (13%).RESULTSFifty-four patients survived induction, all of them achieved CR, in 52 PML/RARα transcript was undetectable after last consolidation therapy. The two patients with molecular persistence of disease received further therapy and then achieved molecular CR. Nine patients (15%) relapsed after a median follow-up of 56 months, 45 patients are alive at the time of analysis (76%). Relapse risk was influenced only by the presence of at least one molecular risk factor (p<0.05), whereas age at diagnosis older than 60 years had only a borderline impact (p=0.105); none of the molecular alterations reached statistical significance if taken alone.Disease free survival (DFS) duration was significantly higher in patients who had none of the molecular risk factor, when compared to patients with at least one (3-years DFS of 100% and 70.8%, respectively, p<0.05, Figure 1). Younger patients had also a longer DFS, with a 3-years DFS of 90.7% and 72% for patients younger or older than 60 years, respectively (p<0.03).Overall survival (OS) analysis led to similar results: patients with no molecular risk factors had a very good outcome when compared to patients with at least one alteration (3-years OS of 100% and 71.5%, respectively, p<0.03). Survival was also influenced by age at diagnosis, as younger patients did significantly better, with 3-years OS of 90% (p<0.05).Again, none of the molecular alterations, if taken alone, had a significant impact on DFS or OS.CONCLUSIONSEven in our small cohort, molecular profile could identify a subset of low-intermediate APL patients at higher risk of relapse, who may take benefit from an intensified consolidation therapy, as it is currently applied to high risk patients defined by WBC at diagnosis. [Display omitted] DisclosuresNo relevant conflicts of interest to declare.

BAALC-associated miR-3151 is an Independent Prognostic Factor in Young Patients With Intermediate-Risk Cytogenetic Acute Myeloid Leukemia

Introduction Patients with intermediate-risk cytogenetic AML (IR-AML) have a heterogeneous prognosis, and are currently further stratified based on determined gene mutations. However, the optimal post-remission therapy, especially in younger patients, is unclear. Recently, miR-3151, a novel microRNA (miRNA) located in intron 1 of the BAALC gene, has been identified. High miR-3151 expression –either alone or in combination with high BAALC levels– independently correlates with poor prognosis in patients ≥ 60 years with normal cytogenetics AML (CN-AML) (Eisfeld AK, et al. Blood 2012). However, the prognostic value of miR-3151 in younger patients (≤60 years) with IR-AML has not been examined. We hypothesized that miR-3151 expression could also be a prognostic marker in younger patients. Aim To analyze whether miR-3151 expression – either alone or in combination with BAALC – improved prognostic assessment in younger patients (up to 60 years) with IR-AML and to characterize in this subset of patients the miRNA signature associated with high miR-3151 expression. Methods Samples were available from two separate cohorts of patients with IR-AML who had received intensive therapy: a training set of 76 patients from a single institution and a validation set of 108 patients from several centers who had been treated within the CETLAM AML-2003 protocol. Information on NPM1, FLT3- ITD and CEBPA was available for both patient cohorts. The expression levels of 670 miRNAs had previously been analyzed in the 76 patients in the training set. In the present study, the expression of miR-3151 and BAALC was analyzed using TaqMan® MicroRNA Assay and TaqMan® Gene Expression Assay (Applied Biosystems), respectively. Expression levels of miR-3151 and BAALC –both alone and in combination – were correlated with patient outcome. Statistical analyses were performed with SPSS v.15.0.1, R software v.2.9.0 and TIGR MultiExperiment Viewerv4.0. Results In the training set, higher expression of miR-3151(dichotomized by its median value of normalized expression) correlated with a shorter 5-year overall survival (OS) (32%±17% vs. 61±17%, p=0.029) and 5-year leukemia-free survival (LFS) (29%±17% vs. 58±17%, p=0.036) in patients ≤ 60 yrs. When the analysis was restricted to patients with CN-AML, miR-3151 expression retained its prognostic significance (p= 0.016). In addition, increased BAALC expression was associated with shorter OS (28%±20% vs. 58±14%, p=0.054) and LFS (17%±18% vs. 55±14%, p=0.039). In the multivariate analysis for OS and LFS, including age, WBC, NPM1 mut, FLT3 -ITD, BAALC and miR-3151 expression levels as covariates, miR-3151 showed independent prognostic significance for OS (p=0.016; HR=2.52, 95% CI: 1.2-5.4),and a statistical trend for LFS (p=0.09). Patients with low expression of both miR-3151 and BAALC had better prognosis (OS: 66%±18% vs. 34±16%, p=0.027; LFS: 67%±20% vs. 27±16%, p=0.009).Interestingly, the combination of both miR-3151 and BAALC retained a significant prognostic value for LFS within the favorable molecular subgroup/ ELN favorable subgroup (patients harboring NPM1 mut without FLT3 -ITD or biallelic CEBPA mut; LFS: 44%±30% vs. 100%, p=0.017) and showed a trend in the unfavorable molecular subgroup/ELN Intermediate II OS: p=0.064 and LFS: p=0.072). In the validation set, miR-3151 overexpression confirmed its prognostic impact in patients in the univariate analysis for OS (45%±12% vs. 26±19%, p=0.039) and LFS (51%±14% vs. 30±24%, p=0.034) and in the multivariate analysis for OS (OS: p=0.038; HR 1.88, IC 95%: 1.06-3.34) and LFS (p= 0.014; HR 2.411 (1.198-4.855) Finally, a supervised analysis revealed that samples exhibiting high levels of miR-3151 expression had a distinctive miRNA signature including miR-509, miR-135a, miR-100*, miR-186*, let-7a* and miR-501. Conclusion miR-3151 is an independent prognostic marker in patients with IR-AML. The study of miR-3151 refines the molecular prognostic stratification of these patients and hence could be of help to guide therapy. Acknowledgements Marina Diaz-Beya is supported by Fundacion Espanola de Hematologia y Hemoterapia. This research is supported by Sociedad Espanola de Hematologia y Hemoterapia and by grants from Fondo de Investigaciones Sanitarias FIS-PI080158. Disclosures: No relevant conflicts of interest to declare.

The Prognostic Relevance of BAALC and ERG Expression Levels in Cytogenetically Normal Pediatric Acute Myeloid Leukemia.

Cytogenetic aberrations are important prognostic factors in acute myeloid leukemia (AML). About 45% of de novo adult AML and 20% of pediatric AML lack cytogenetic abnormalities, so identification of predictive molecular markers might improve therapy. Mutation status of FLT3, NPM1 genes and gene expression levels of ERG, BAALC have been postulated as possible prognostic markers in pediatric AML with normal karyotype. Pretreatment blood samples from 47 cytogenetically normal AML patients were analysed for BAALC and ERG expression using real time RT-PCR. The patients were dichotomized at BAALC and ERG mean expression into low and high expression based on the median expression as cutoff. BAALC showed high expression in (24/47; 51.1%) of patients and ERG high expression was detected in (22/47; 46.6%). With follow-up for 1year, patients with high BAALC and high ERG had inferior EFS (P=0.001, P=0.017 respectively), overall survival (P=0.001, 0.08 respectively), and low rates of induction remission (P=0.001, P=0.0017 respectively) as compared to those with low expression. Also there was significant positive association between high expression of BAALC; ERG and FLT-ITD mutations (P=0.016; P=0.007 respectively). Multivariable analysis confirmed that high BAALC expression is an independent risk factor for EFS [HR for EFS 1.9(1.04-3.46) P=0.037]; and OS [HR OS 1.55(1.7-3.36) P=0.03]. Over expression of BAALC could predict adverse clinical outcome and may define important risk factor in cytogenetically normal pediatric AML.

NPM1 Mutated AML Is Associated With Lower Expression Of Poor Prognostic Markers BAALC, ERG and MN1 In Adult Patients With Acute Myeloid Leukaemia

Acute myeloid leukemia (AML) is a clinically and biologically complex and heterogeneous hematopoietic neoplasm. Recent advances in acute myeloid leukemia (AML) biology have lead to prognosticate and predict treatment outcome in AML based on molecular markers. Mutations in NPM1, CEBPA are considered good prognosis and High BAALC, ERG &MN1 expression associate with worse outcome in AML patients treated with standard chemotherapy. Although many efforts have been made to identify genetic mutations and modulated gene expression levels that can be used to predict outcomes in patients with AML, the association between these prognostic markers has not been evaluated. We have reported previously that the NPM1 mutated patients have significantly high dCK and hENT1 gene expression (involved in cytarabine metabolism) and low ABCG2 and ABCB1transporter expression (Abraham et al, ASH abstracts; Nov 2011; 118: 3481 and Nov 2012; 120: 143), suggesting that the good prognostic nature of this mutation is possibly due to the better metabolism and transport of the chemotherapeutic drugs used in induction therapy. We extended this study to look for association between NPM1/FLT3 mutation status and the RNA expression of other good or poor prognostic markers in patients with AML.We prospectively included 274 adult patients with AML in this study. The median age was 42 years (range 16-74y). AML was diagnosed according to the FAB and WHO classifications. There were 238 patients with de novo AML; Secondary AML -6; Therapy related AML- 2 and Relapsed AML-28. Bone marrow cytogenetics and immunophenotyping analysis was available for all patients at diagnosis and/or relapse. Diagnostic bone marrow MNCs were isolated by ficoll- density gradient centrifugation and stored in trizol reagent for RNA expression and mutation detection. RT-PCR was used to screen AML-ETO and Inv 16, and the expression of BAALC, ERG1, MN1, CXCR4 and WT1were analyzed using RQ-PCR. NPM1-c, FLT3 ITD and TKD were screened using DNA PCR followed by gene-scan, sequencing or RFLP methods. The basic demographics and the frequency of the markers are listed in Table 1. When analyzed separately in normal karyotype AML (NK-AML), the frequencies of the mutations were: NPM1: 52.2%; FLT3-ITD: 24%; TKD: 4.3%.When the RNA expression of BAALC, WT1, ERG1, CXCR4 and MN1 was compared in patients with NPM1 or FLT3 mutations, we noticed that patients with NPM1 had significantly low expression of BAALC, MN1 and ERG1 while those with FLT3 mutations (ITD or TKD) had higher expression of these genes (Figure1). There was no significant association with CXCR4 or WT1 expression and these mutations. When analyzed separately in the normal karyotype AML, these associations were still significant. In addition, the relapsed patients had significantly higher expression of BAALC, MN1, and ERG1 RNA compared to de-novoAML cases (data not shown).To conclude, we show that NPM1 or FLT3 mutations acquire the prognostic significance due to several factors including BAALC, ERG1 and MN1expression levels in addition to drug metabolizing enzymes' and drug transporter expression. These factors must be taken into consideration when attempting to personalize chemotherapy in AML. [Display omitted] Disclosures:No relevant conflicts of interest to declare.

ERG Overexpression Is Highly Associated With ERG Gene Amplifications In Patients With Myeloid Malignancies

BackgroundThe proto-oncogene ERG is located on chromosome 21q22 and overexpression of ERG was shown to have an adverse impact on outcome in cytogenetically normal AML (CN-AML). Acquired gain of chromosome 21 (+21) is a recurrent cytogenetic abnormality in AML, however, the pathogenetic impact remains elusive. Data indicate that +21 could be the underlying mechanism for altered expression of genes located in the respective regions, such as ERG, which might contribute to the pathogenesis in myeloid malignancies with +21. Aims1) To investigate a possible relationship between ERG copy numbers and variations in ERG mRNA expression levels in patients (pts) with myeloid malignancies. 2) Analysis of ERG expression in CN-AML to reveal a possible association between ERG overexpression and other relevant molecular markers and to ascertain the prognostic impact of ERGin context of these markers. MethodsERG mRNA expression and ERG copy numbers were analyzed using a hydrolysis probe based real-time PCR assay. 1) To address ERG expression in relation to +21 the following cohorts were analyzed: 62 AML pts with a complex karyotype including +21 (CK+21); 44 AML pts with a non-complex aberrant karyotype including +21 (AK+21); 19 pts with various myeloid malignancies (10 de novo AML, 3 MDS, 1 s-AML, 2 t-AML, 1 MDS/AML, 1 t-MDS, 1 MDS/MPN) all of them showing ERG amplification by interphase FISH and array CGH (ERG-Amp). In addition, 32 CK-AML and 330 CN-AML pts without +21 or ERGamplification were analyzed. Results were expressed as mean values±SEM. Expression levels/DNA copy numbers were compared by t-test. 2)ERG expression was assessed in a cohort of 330 patients (<65 years) with de novo CN-AML. Female/male ratio was 169/161. To distinguish low from high ERG expressers the median %ERG/ABL1 level was used. BAALC expression levels were analyzed accordingly. Expression levels were correlated with clinical outcome and with the presence of mutations (mut) in ASXL1 (n=330), CEBPA (n=330), DNMT3A (n=261), FLT3-TKD (n=330), IDH1R132 (n=328), IDH2R140 (n=328), IDH2R172 (n=328), NPM1 (n=330), NRAS (n=330), RUNX1 (n=329), TET2 (n=166), WT1 (n=329) and FLT3-ITD (n=330), and with MLL-PTD (n=330) and BAALCexpression (n=328). Results1) Analysis of pts with +21 or ERG-Amp revealed significantly higher expression levels of ERG in pts with +21 (AK+21 and CK+21 combined, 331 ± 28) and ERG-Amp (606 ± 127) as compared to pts with CN-AML (229 ± 10; p=0.001, p=0.008, respectively) or CK-AML (177 ± 36; p=0.001, p=0.004, respectively). Mean ERG expression was even higher in pts with ERG-Amp (606 ± 127) as compared to pts with +21 (331 ± 28, p=0.047). Quantification of ERG copy numbers on DNA level showed good correlation to ERG mRNA expression, with abundantly higher ERG DNA amount in +21 (3.25 ±0.14) and moreover in ERG-Amp (9.21 ±1.05) as compared to CN-AML and CK-AML (combined: 2.20 ± 0.05; p<0.001 and p<0.001, respectively). 2) In CN-AML, %ERG/ABL1 levels ranged from 0.078 to 1,016.027 (median: 188.904). High ERG expression was associated with lower age (mean: 48.7 vs. 52.4 years, p=0.002), higher white blood cell (WBC) count (mean: 64.8 vs. 44.4 x 109/L, p=0.019), FLT3-ITDmut/wt ratio≥0.5 (51/165, 30.9% vs. 24/165, 14.5%, p=0.001), IDH2R172mut (6/164, 3.7% vs. 0/164, 0.0%, p=0.030) and high BAALC expression (104/164, 63.4% vs. 59/164, 36.0%, p<0.001), as compared to low ERG expression. In contrast, NPM1mut (91/165, 55.2% vs. 118/165, 71.5%, p=0.003), IDH1R132mut (10/165, 6.1% vs. 29/163, 17.8%, p=0.001) and TET2mut (10/76, 13.2% vs. 22/90, 24.4%, p=0.077) were less frequent in high ERG expressers. Survival analysis revealed inferior overall survival (OS at 3 years: 52.2% vs. 68.7%, p=0.021) and event free survival (EFS at 3 years: 34.6% vs. 43.1%, p=0.052) for high ERG expressers as compared to low ERG expressers. In a multivariate analysis adjusted for age, WBC, BAALC expression, FLT3-ITDmut/wt ratio≥0.5, MLL-PTD and WT1mut, high ERG expression revealed a trend towards an adverse impact on OS (p=0.069), while no impact on EFS was observed. Conclusions1) Gain of chromosome 21 and especially amplification of chromosomal band 21q22 is a mechanism for ERG overexpression. This might indicate ERG as an important factor contributing to the pathogenesis and progression of myeloid malignancies with gain of chromosome 21. 2) In CN-AML, ERG overexpression is associated to several molecular markers and has a negative impact on OS and EFS. Disclosures:Weber:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Noel:MLL Munich Leukemia Laboratory: Employment. Alpermann:MLL Munich Leukemia Laboratory: Employment. Kern:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Schnittger:MLL Munich Leukemia Laboratory: Employment, Equity Ownership.

BAALC and WT1 expressions from diagnosis to hematopoietic stem cell transplantation: consecutive monitoring in adult patients with core‐binding‐factor‐positive AML

No consecutive analysis of BAALC and WT1 expressions associated with core-binding factor AML (CBF-AML) from diagnosis to hematopoietic stem cell transplantation (HSCT) has yet been reported. We investigated BAALC and WT1 expressions using a method of real-time quantitative polymerase chain reaction (RQ-PCR) at diagnosis, after induction chemotherapy, at pre-HSCT, and at post-HSCT period in 45 consecutive patients [t(8,21) (n = 28), inv(16) (n = 17)], who received HSCT as a post-remission treatment. BAALC and WT1 RQ-PCR decrement ratio (DR) was also calculated at post-induction chemotherapy, at pre-HSCT, and at post-HSCT compared with the diagnostic level. Higher BAALC expression at diagnosis showed significantly inferior OS (P = 0.031), EFS (P = 0.011), and higher CIR (P = 0.002) rates. At post-HSCT, both higher BAALC and WT1 expressions showed significantly inferior OS (P = 0.005, 0.016), EFS (P = 0.002, 0.006), and higher CIR (P = 0.001, 0.003) rates. A subgroup of t(8;21) showing higher BAALC and WT1 expressions at post-HSCT were also associated with inferior OS (P = 0.018, 0.015) and higher CIR rates (P = 0.019, 0.011). While BAALC DR showed no significant results on outcomes, WT1 DR more than 2-log at post-HSCT showed significantly lower CIR rate (P = 0.028). This study showed that higher post-HSCT BAALC and WT1 expressions in patients with CBF-AML may be good markers of minimal residual disease for the prediction of survival and relapse after HSCT.

A stem cell-like gene expression signature associates with inferior outcomes and a distinct microRNA expression profile in adults with primary cytogenetically normal acute myeloid leukemia

Acute myeloid leukemia (AML) is hypothesized to be sustained by self-renewing leukemia stem cells (LSCs). Recently, gene expression signatures (GES) from functionally defined AML LSC populations were reported, and expression of a 'core enriched' (CE) GES, representing 44 genes activated in LCSs, conferred shorter survival in cytogenetically normal (CN) AML. The prognostic impact of the CE GES in the context of other molecular markers, including gene mutations and microRNA (miR) expression alterations, is unknown and its clinical utility is unclear. We studied associations of the CE GES with known molecular prognosticators, miR expression profiles, and outcomes in 364 well-characterized CN-AML patients. A high CE score (CE(high)) associated with FLT3-internal tandem duplication, WT1 and RUNX1 mutations, wild-type CEBPA and TET2, and high ERG, BAALC and miR-155 expression. CE(high) patients had a lower complete remission (CR) rate (P=0.003) and shorter disease-free (DFS, P<0.001) and overall survival (OS, P<0.001) than CE(low) patients. These associations persisted in multivariable analyses adjusting for other prognosticators (CR, P=0.02; DFS, P<0.001; and OS, P<0.001). CE(high) status was accompanied by a characteristic miR expression signature. Fifteen miRs were upregulated in both younger and older CE(high) patients, including miRs relevant for stem cell function. Our results support the clinical relevance of LSCs and improve risk stratification in AML.

Implication of higher BAALC expression in combination with other gene mutations in adult cytogenetically normal acute myeloid leukemia

Data for 125 patients with cytogenetically normal acute myeloid leukemia (CN-AML) regarding BAALC and combinatorial molecular markers at diagnosis were evaluated. Fewer patients with higher BAALC expression at diagnosis achieved a complete remission (CR) (49.2 vs. 75.8%, p = 0.002) after the first cycle of chemotherapy, and there were more primary refractory cases (37.3 vs. 18.2%, p = 0.017). In a combinatorial analysis, FLT3-ITD-positive patients with higher BAALC showed more refractoriness and the worst overall survival (OS) (p < 0.001) and disease-free survival (DFS) (p < 0.001) in CN-AML. When NPM1-mutated CN-AML was combined with either FLT3-ITD mutation or higher BAALC expression, both OS (p = 0.043) and DFS (p = 0.008) were worse; when combined with both, it showed the worst OS (p < 0.001) and DFS (p = 0.004). Higher BAALC expression and FLT3-ITD mutation, both individually and in combination, were associated with worse survival outcomes in CN-AML, and this was also applicable in NPM1-mutated CN-AML, known as a favorable-risk group.

MicroRNA Dysregulation in Acute Myeloid Leukemia

In the article that accompanies this editorial, Marcucci et al present data on the clinical significance of the overexpression of miR-155 in patients with cytogenetically normal acute myeloid leukemia (CN-AML). miR-155 is a microRNA that is dysregulated in aggressive lymphomas, in the aggressive form of CLL, and in some solid malignancies such as lung, breast, and colorectal cancer. miR-155 has been shown to inhibit expression of tumor suppressors and genes involved in DNA repair. Interestingly, dysregulation of miR-155 in B cells of mice causes acute lymphoblastic leukemia and high-grade lymphomas. The authors carried out mRNA and microRNA profiling by using microarrays and measured the expression of the transcripts of the miR-155 gene by nCounter technology (NanoString, Seattle, WA), a sensitive amplification independent method. They investigated CN-AML patients, including 153 younger ( 60 years) and 210 older ( 60 years) patients, with untreated primary CN-AML who received intensive first-line therapy on CALGB trials and had diagnostic bone marrow or blood specimens available for molecular analyses. The results of their careful analysis show that miR-155 expression levels constitute an independent prognostic factor in patients with CN-AML. While higher miR-155 expression levels had a negative impact on the outcome of younger and older patients, higher miR-155 expression was associated with lower complete response (CR) rate, and shorter disease-free survival (DFS) and overall survival (OS) in younger patients. Higher miR-155 expression level was associated only with lower CR and shorter OS in older patients. Such findings could be related to biologic differences and differences in the intensity of consolidation therapy. At diagnosis, high miR-155 levels occurred more frequently in patients with AML who were FLT3-ITD positive, RUNX1-mutated, WT1 mutated, and had high ERG and BAALC expressors, and less frequently in CEBPA-mutated, IDH2-mutated and FLT3-tyrosine kinase–positive patients with AML. Thus, higher miR-155 levels associate with unfavorable prognosticators and predict worse CR and survival in both young and old patients. In multivariable analysis, patients with CN-AML with higher levels of miR-155 were approximately 50% less likely to achieve CR. Higher miR-155 expressors had also a 60% increased risk of death and were independent of FLT3-ITD. An international panel of experts on CN-AML on behalf of the European LeukemiaNet recommended a modified classification of patients with CN-AML. When the authors analyzed the prognostic significance of miR-155 in patients classified in the ENL favorable genetic group, younger patients with high miR-155 expression had significantly lower CR rates and shorter event-free survival and OS than patients with low expression, respectively. These correlations were not found with any other microRNA. This is the first clinical study, to our knowledge, where expression of miR-155 was evaluated by using the nCounter technology to understand how different expression levels of miR-155 may affect the aggressiveness of the disease, outcome, and response to treatment of patients with CN-AML. The results indicate that high levels of expression of miR-155 positively correlate with antiapoptotic activity and NF B activation. Although dysregulation of miR-155 in B cells and myeloid cells has been shown to be associated to aggressive malignancy and myeloproliferative disorders respectively in mouse models, the present study tries to assess the role of the dysregulation of this microRNA in patients with CN-AML. Their results support the hypothesis that miR-155 expression contributes to different degrees of aggressiveness in leukemia by affecting proliferation and survival of the leukemia cells. A conclusion of this study, as clearly indicated by the authors, is that if we want to have an effect in the treatment of this group of AML patients, we should try to revert miR-155 overexpression, for example, by using anti-miR-155 oligonucleotides or by inhibiting the pathways that regulate the levels of miR-155 expression. In addition, given that miR-155 is relatively easy to measure at diagnosis, we should consider the levels of miR-155 as a biomarker for risk stratification and guidance for treatment.

A standardized microarray assay for the independent gene expression markers in AML: EVI1 and BAALC

High levels of BAALC, ERG, EVI1 and MN1 expression have been associated with shorter overall survival in AML but standardized and clinically validated assays are lacking. We have therefore developed and optimized an assay for standardized detection of these prognostic genes for patients with intermediate cytogenetic risk AML. In a training set of 147 intermediate cytogenetic risk cases we performed cross validations at 5 percentile steps of expression level and observed a bimodal significance profile for BAALC expression level and unimodal significance profiles for ERG and MN1 levels with no statistically significant cutoff points near the median expression level of BAALC, ERG or MN1. Of the possible cutoff points for expression levels of BAALC, ERG and MN1, just the 30th and 75th percentile of BAALC expression level and the 30th percentile of MN1 expression level cutoff points showed clinical significance. Of these only the 30th percentile of BAALC expression level reproduced in an independent verification (extended training) data set of 242 cytogenetically normal AML cases and successfully validated in an external cohort of 215 intermediate cytogenetic risk AML cases. Finally, we show independent prognostic value for high EVI1 and low BAALC in multivariate analysis with other clinically relevant molecular AML markers. We have developed a highly standardized molecular assay for the independent gene expression markers EVI1 and BAALC.

Low MDR1 and BAALC expression Identifies a New Subgroup of Adult Cytogenetically Normal Acute Myeloid Leukemia with a Favorable Outcome

Abstract 4312 OBJECTIVE:Cytogenetically normal acute myeloid leukemia (AML) is a heterogeneous disease, in terms of genetic/molecular abnormalities resulting into marked differences in outcome. We demonstrated that MDR1, BAALC expression was of prognostic significance and high MDR1 expression correlated with a high BAALC expression (r=0.487, P<0.001) in cytogenetically normal AML in the prophase study then we hypothesized that MDR1 and BAALC expression together would better identify the patient’s risk profile. METHODS:Pretreatment bone marrow samples from 92 cytogenetically normal AML patients were analyzed for MDR1 and BAALC mRNA expression by real-time reverse transcriptase polymerase chain reaction. Patients were divided into low MDR1 and BAALC expression group and combined group (high MDR1 and/or high BAALC expression) according to MDR1 and BAALC levels and were compared for clinical outcome. RESULTS:73 cases of 92 cytogenetically normal AML patients got CR after the first block with a CR rate being 79.3%. However, 29 cases of the CR patients relapsed with the relapsed rate being 39.7%. In contrast, Patients with low expression of both MDR1 and BAALC had a higher CR rate (93.3%vs72.6%, P=0.021), lower relapse rate (7.1% vs. 42.5%, P=0.000), longer OS (50.3% vs 17.8%,P=0.001) than high MDR1 and/or high BAALC expression (combined group) in cytogenecally normal AML. Results showed no statistical difference in CR rate (93.3%vs85.7%, P=0.341),relapse rate (7.1% vs. 8.8%, P=0.000) and OS (50.3% vs 63.1%,P=0.431) for cytogenetically normal patients with both MDR1 and BAALC low expression comparing to those with low-risk cytogenetically abnormal. CONCLUSION:The combined assessment of BAALC and MDR1 expression can improve treatment stratification in adult cytogenetically normal AML. Low expression of both MDR1 and BAALC identifies cytogenetically normal AML patients with a favorable long-term outcome. Disclosures:No relevant conflicts of interest to declare.

High BAALC Expression in Cytogenetically Normal Acute Myeloid Leukemia Strongly Correlates with Adverse Markers Such As RUNX1mut, MLL-PTD and FLT3-ITD and Is Useful for Disease Monitoring

Abstract 1376▪▪This icon denotes a clinically relevant abstract Introduction:BAALC expression is thoroughly explored in cytogenetically normal AML (CN-AML) and has been shown to be associated with an adverse outcome. Nevertheless, its prognostic importance in relation to other molecular markers and its relevance for detection of minimal residual disease (MRD) remains to be defined. The objective of this study was to evaluate the prognostic impact of BAALC expression on clinical outcome in the context of other relevant molecular prognosticators and to examine its utility as a marker for detection of MRD in CN-AML. Patients:BAALC mRNA expression was analyzed in a cohort of 332 patients with de novo CN-AML. The cohort was composed of 169 females (50.9%) and 163 males (49.1%). Age ranged from 18.3 to 64.8 years (median: 52.9). Data on other molecular markers was available in: FLT3-ITD: n=332, NPM1: n=332, RUNX1: n=330, CEBPA: n=332, MLL-PTD: n=332, ASXL1: n=330, FLT3-TKD: n=331, IDH1G105: n=229, IDH1R132: n=253, IDH2: n=232, NRAS: n=254, WT1 mut: n=247, TET2: n=74 and TP53: n=182. In addition, BAALC expression was assessed in 25 follow-up samples of 8 patients in comparison with an established MRD marker. Methods:To assess BAALC mRNA expression levels RQ-PCR was performed by the use of the Applied Biosystems 7500 Fast Real Time PCR System. BAALC expression was normalized against the expression of the control gene ABL1. The median ratio BAALC/ABL1 was used to separate low from high BAALC expressers. Expression data of diagnostic samples was correlated to clinical outcomes and to the presence of molecular mutations. BAALC expression ratios of follow-up samples were also correlated to the status of other molecular markers available in the same patients. Results:1) Evaluation of prognostic relevance: Expression ratios of BAALC/ABL1 represented a continuum ranging from 0.001 to 80.199 (median: 0.321). In agreement with previous studies, patients with high BAALC expression had shorter overall survival (OS at 3 years: 51.4% vs 73.0%, p=0.046) and event free survival (EFS at 3 years: 38.5% vs 50.6%, p=0.021) as compared to low BAALC expressers. Though, associations of BAALC expression to other molecular markers were found. In high BAALC expressers, as compared to low BAALC expressers, the following mutations were more frequent: RUNX1 mut (32/164, 19.5% vs 2/166, 1.2%, p<0.001), MLL-PTD (22/166, 13.3% vs 5/166, 3.0%, p=0.001) and FLT3-ITDmut/wt ratio>0.5 (51/166, 30.7% vs 24/166, 14.5%, p=0.001), whereas NPM1 mut were less frequent (72/166, 43.3% vs 138/166, 83.1%, p<0.001). In univariable Cox regression analyses shorter OS and EFS was associated with higher age, higher WBC count, high BAALC expression and the presence of at least one of the established adverse markers RUNX1 mut, MLL-PTD, or FLT3-ITDmut/wt ratio>0.5 grouped together as one parameter (OS, p<0.001, <0.001, 0.0048, <0.001, respectively; EFS, p=0.002, <0.001, 0.022, <0.001, respectively). In multivariable models, BAALC expression had an independent impact on EFS (p=0.042) but not on OS. Further, Kaplan Meier analysis within the subgroup with adverse markers (RUNX1 mut, MLL-PTD, or FLT3-ITDmut/wt ratio>0.5, n=98) revealed no additional impact of BAALC expression on OS or EFS. Also within the prognostically favorable subgroup with NPM1 mut/FLT3-ITDmut/wt ratio<0.5 high BAALC expression had no impact on OS or EFS. 2) Validation as follow-up marker:To evaluate the impact of BAALC expression for disease monitoring during follow-up, the BAALC/ABL1 ratio of high BAALC expressers was compared to the %MLL-PTD/ABL1 or %RUNX1 mut levels in patients who had at least one of these aberrations in parallel. In total, 33 diagnostic and follow-up samples of 8 patients were analyzed. Comparison of BAALC/ABL1 ratios to mutational status of MLL-PTD and/or RUNX1 revealed a significant correlation (r=0.577, p<0.001). Additionally, in one case with paired samples at diagnosis and relapse, BAALC expression levels at diagnosis and at relapse were in the same range (BAALC/ABL1: 10.870 vs 17.600). Conclusion:1) BAALC expression in CN-AML predicts an adverse clinical outcome, but is associated with other well established prognostic markers. Thus, in our study BAALC expression had no independent prognostic impact on OS when analyzed together with RUNX1, MLL-PTD, FLT3-ITD and NPM1. 2) Correlation of BAALC expression with MLL-PTD and RUNX1 during follow up indicates that BAALC expression is a potential target for MRD monitoring. Disclosures:Weber:MLL Munich Leukemia Laboratory: Employment. Alpermann:MLL Munich Leukemia Laboratory: Employment. Eder:MLL Munich Leukemia Laboratory: Employment. Dicker:MLL Munich Leukemia Laboratory: Employment. Jeromin:MLL Munich Leukemia Laboratory: Employment. Kohlmann:MLL Munich Leukemia Laboratory: Employment. Fasan:MLL Munich Leukemia Laboratory: Employment. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Kern:MLL Munich Leukemia Laboratory: Equity Ownership. Haferlach:MLL Munich Leukemia Laboratory: Equity Ownership. Schnittger:MLL Munich Leukemia Laboratory: Equity Ownership.