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BACKGROUND: Patients with metastatic colorectal cancer with the BRAF V600E mutation have a poor prognosis, with a median overall survival of 4 to 6 months after failure of initial therapy. Inhibition of BRAF alone has limited activity because of pathway reactivation through epidermal growth factor receptor signaling. METHODS: In this open-label, phase 3 trial, we enrolled 665 patients with BRAF V600E-mutated metastatic colorectal cancer who had had disease progression after one or two previous regimens. Patients were randomly assigned in a 1:1:1 ratio to receive encorafenib, binimetinib, and cetuximab (triplet-therapy group); encorafenib and cetuximab (doublet-therapy group); or the investigators' choice of either cetuximab and irinotecan or cetuximab and FOLFIRI (folinic acid, fluorouracil, and irinotecan) (control group). The primary end points were overall survival and objective response rate in the triplet-therapy group as compared with the control group. A secondary end point was overall survival in the doublet-therapy group as compared with the control group. We report here the results of a prespecified interim analysis. RESULTS: The median overall survival was 9.0 months in the triplet-therapy group and 5.4 months in the control group (hazard ratio for death, 0.52; 95% confidence interval [CI], 0.39 to 0.70; P

Preclinical evidence suggests that concomitant BRAF and EGFR inhibition leads to sustained suppression of MAPK signaling and suppressed tumor growth in BRAFV600E colorectal cancer models. Patients with refractory BRAFV600-mutant metastatic CRC (mCRC) were treated with a selective RAF kinase inhibitor (encorafenib) plus a monoclonal antibody targeting EGFR (cetuximab), with (n = 28) or without (n = 26) a PI3Kα inhibitor (alpelisib). The primary objective was to determine the maximum tolerated dose (MTD) or a recommended phase II dose. Dose-limiting toxicities were reported in 3 patients receiving dual treatment and 2 patients receiving triple treatment. The MTD was not reached for either group and the phase II doses were selected as 200 mg encorafenib (both groups) and 300 mg alpelisib. Combinations of cetuximab and encorafenib showed promising clinical activity and tolerability in patients with BRAF-mutant mCRC; confirmed overall response rates of 19% and 18% were observed and median progression-free survival was 3.7 and 4.2 months for the dual- and triple-therapy groups, respectively.Significance: Herein, we demonstrate that dual- (encorafenib plus cetuximab) and triple- (encorafenib plus cetuximab and alpelisib) combination treatments are tolerable and provide promising clinical activity in the difficult-to-treat patient population with BRAF-mutant mCRC. Cancer Discov; 7(6); 610–9. ©2017 AACR.See related commentary by Sundar et al., p. 558.This article is highlighted in the In This Issue feature, p. 539

Salivary duct carcinomas (SDC) and Her2/Neu3-overexpressing invasive breast carcinomas (HNPIBC/IBC) are histologically indistinguishable. We investigated whether common histopathologic and immunophenotypic features of SDC and IBC are mirrored by a similar microRNA (miRNA) profile. MiRNA profiling of 5 SDCs, 6 IBCs Her2/Neu3+, and 5 high-grade ductal breast carcinoma in situ (DCIS) was performed by NanoString platform. Selected miRNAs and HOXA1 gene were validated by RT-PCR. We observed similar miRNA expression profiles between IBC and SDC with the exception of 2 miRNAs, miR-10a and miR-142-3p, which were higher in IBC tumors. DCIS tumors displayed increased expression of miR-10a, miR-99a, miR-331-3p and miR-335, and decreased expression of miR-15a, miR-16 and miR-19b compared to SDC. The normal salivary gland and breast tissues also showed similar expression profiles. Interestingly, miR-10a was selectively increased in both IBC and normal breast tissue compared to SDC and normal salivary gland tissue. Moreover, our NanoString and RT-PCR data confirmed that miR-10a was upregulated in IBC and DCIS compared to SDC. Finally, we show downregulation of HOXA1, a miR-10 target, in IBC tumors compared to normal breast tissue. Taken together, our data demonstrates that, based on miRNA profiling, SDC is closely related to HNPIBC. Our results also suggest that miR-10a is differentially expressed in IBC compared to SDC and may have potential utility as a diagnostic biomarker in synchronous or metachronous malignant epithelial malignancies involving both organs. In addition, miR-10a could be playing an important role as a mammary-specific oncogene, involved in breast cancer initiation (DCIS) and progression (IBC), through mechanisms that include modulation of HOXA1 gene expression. ELECTRONIC SUPPLEMENTARY MATERIAL: The online version of this article (10.1007/s12105-018-0971-x) contains supplementary material, which is available to authorized users.

Receptor-interacting protein kinase-3 (RIP3 or RIPK3) is an essential part of the cellular machinery that executes "programmed" or "regulated" necrosis. Here we show that programmed necrosis is activated in response to many chemotherapeutic agents and contributes to chemotherapy-induced cell death. However, we show that RIP3 expression is often silenced in cancer cells due to genomic methylation near its transcriptional start site, thus RIP3-dependent activation of MLKL and downstream programmed necrosis during chemotherapeutic death is largely repressed. Nevertheless, treatment with hypomethylating agents restores RIP3 expression, and thereby promotes sensitivity to chemotherapeutics in a RIP3-dependent manner. RIP3 expression is reduced in tumors compared to normal tissue in 85% of breast cancer patients, suggesting that RIP3 deficiency is positively selected during tumor growth/development. Since hypomethylating agents are reasonably well-tolerated in patients, we propose that RIP3-deficient cancer patients may benefit from receiving hypomethylating agents to induce RIP3 expression prior to treatment with conventional chemotherapeutics.

Emerging data demonstrate important roles for the TYRO3/AXL/MERTK receptor tyrosine kinase (TAM RTK) family in diverse cancers. We investigated the prognostic relevance of GAS6 expression, encoding the common TAM RTK ligand, in 270 adults (n=71 aged

Recently, we showed that increased miR-181a expression was associated with improved outcomes in cytogenetically normal acute myeloid leukemia (CN-AML). Interestingly, miR-181a expression was increased in CN-AML patients harboring CEBPA mutations, which are usually biallelic and associate with better prognosis. CEBPA encodes the C/EBPα transcription factor. We demonstrate here that the presence of N-terminal CEBPA mutations and miR-181a expression are linked. Indeed, the truncated C/EBPα-p30 isoform, which is produced from the N-terminal mutant CEBPA gene or from the differential translation of wild-type CEBPA mRNA and is commonly believed to have no transactivation activity, binds to the miR-181a-1 promoter and up-regulates the microRNA expression. Furthermore, we show that lenalidomide, a drug approved for myelodysplastic syndromes and multiple myeloma, enhances translation of the C/EBPα-p30 isoform, resulting in higher miR-181a levels. In xenograft mouse models, ectopic miR-181a expression inhibits tumor growth. Similarly, lenalidomide exhibits antitumorigenic activity paralleled by increased miR-181a expression. This regulatory pathway may explain an increased sensitivity to apoptosis-inducing chemotherapy in subsets of AML patients. Altogether, our data provide a potential explanation for the improved clinical outcomes observed in CEBPA-mutated CN-AML patients, and suggest that lenalidomide treatment enhancing the C/EBPα-p30 protein levels and in turn miR-181a may sensitize AML blasts to chemotherapy.

Purpose To identify a robust prognostic gene expression signature as an independent predictor of survival of patients with acute myeloid leukemia (AML) and use it to improve established risk classification. Patients and Methods Four independent sets totaling 499 patients with AML carrying various cytogenetic and molecular abnormalities were used as training sets. Two independent patient sets composed of 825 patients were used as validation sets. Notably, patients from different sets were treated with different protocols, and their gene expression profiles were derived using different microarray platforms. Cox regression and Kaplan-Meier methods were used for survival analyses. Results A prognostic signature composed of 24 genes was derived from a meta-analysis of Cox regression values of each gene across the four training sets. In multivariable models, a higher sum value of the 24-gene signature was an independent predictor of shorter overall (OS) and event-free survival (EFS) in both training and validation sets (P < .01). Moreover, this signature could substantially improve the European LeukemiaNet (ELN) risk classification of AML, and patients in three new risk groups classified by the integrated risk classification showed significantly (P < .001) distinct OS and EFS. Conclusion Despite different treatment protocols applied to patients and use of different microarray platforms for expression profiling, a common prognostic gene signature was identified as an independent predictor of survival of patients with AML. The integrated risk classification incorporating this gene signature provides a better framework for risk stratification and outcome prediction than the ELN classification.

Purpose To determine the association of RUNX1 mutations with therapeutic outcome in younger and older patients with primary cytogenetically normal acute myeloid leukemia (CN-AML) and with gene/microRNA expression signatures. Patients and Methods Younger (< 60 years; n = 175) and older (≥ 60 years; n = 225) patients with CN-AML treated with intensive cytarabine/anthracycline-based first-line therapy on Cancer and Leukemia Group B protocols were centrally analyzed for RUNX1 mutations by polymerase chain reaction and direct sequencing and for established prognostic gene mutations. Gene/microRNA expression profiles were derived using microarrays. Results RUNX1 mutations were found in 8% and 16% of younger and older patients, respectively (P = .02). They were associated with ASXL1 mutations (P < .001) and inversely associated with NPM1 (P < .001) and CEBPA (P = .06) mutations. RUNX1-mutated patients had lower complete remission rates (P = .005 in younger; P = .006 in older) and shorter disease-free survival (P = .058 in younger; P < .001 in older), overall survival (P = .003 in younger; P < .001 in older), and event-free survival (P < .001 for younger and older) than RUNX1 wild-type patients. Because RUNX1 mutations were more common in older patients and almost never coexisted with NPM1 mutations, RUNX1 mutation–associated expression signatures were derived in older, NPM1 wild-type patients and featured upregulation of genes normally expressed in primitive hematopoietic cells and B-cell progenitors, including DNTT, BAALC, BLNK, CD109, RBPMS, and FLT3, and downregulation of promoters of myelopoiesis, including CEBPA and miR-223. Conclusion RUNX1 mutations are twice as common in older than younger patients with CN-AML and negatively impact outcome in both age groups. RUNX1-mutated blasts have molecular features of primitive hematopoietic and lymphoid progenitors, potentially leading to novel therapeutic approaches.

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

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

We compared the outcomes of patients age 60-70 years with acute myelogenous leukemia receiving reduced-intensity allogeneic hematopoietic cell transplantation (HCT) in first remission (CR1) reported to the Center for International Blood and Marrow Research (n = 94) with the outcomes in patients treated with induction and postremission chemotherapy on Cancer and Leukemia Group B protocols (n = 96). All patients included had been in CR1 for at least 4 months. The HCT recipients were slightly younger than the chemotherapy patients (median age, 63 years vs 65 years; P < .001), but there were no significant between-group differences in the proportion with therapy-related leukemia or in different cytogenetic risk groups. Time from diagnosis to CR1 was longer for the HCT recipients (median, 44 days vs 38 days; P = .031). Allogeneic HCT was associated with significantly lower risk of relapse (32% vs 81% at 3 years; P < .001), higher nonrelapse mortality (36% vs 4% at 3 years; P < .001), and longer leukemia-free survival (32% vs 15% at 3 years; P = .001). Although overall survival was longer for HCT recipients, the difference was not statistically significant (37% vs 25% at 3 years; P = .08). Our findings suggest that reduced-intensity conditioning allogeneic HCT in patients age 60-70 with acute myelogenous leukemia in CR1 reduces relapse and improves leukemia-free survival. Strategies that reduce nonrelapse mortality may yield significant improvements in overall survival.

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.

688 Background: BRAFV600E mutation occurs in 10%-–15% of patients (pts) with mCRC and confers a poor prognosis. After first-line therapy, standard second-line therapies provide limited benefit, with objective response rates (ORRs) < 10%, and overall survival (OS) of 4–6 months (mo). BEACON CRC (NCT02928224) is a 3-arm phase 3 trial of triplet therapy with the BRAF inhibitor ENCO + MEK inhibitor BINI + anti–EGFR antibody CETUX vs ENCO + CETUX vs a control arm (irinotecan/FOLFIRI + CETUX) in pts with BRAFV600E mCRC in the second or third-line setting. A safety lead-in (SLI) of the triplet therapy was conducted in 30 pts prior to initiation of the randomized part of the trial. Previously reported confirmed ORR in 29 pts with BRAFV600E mCRC was 48% and median progression-free survival (PFS) was 8.0 mo (Van Cutsem E, et al. Ann Oncol. 2018;29:O-027). Here we present updated safety and efficacy results including mature OS. Methods: All pts in the SLI received ENCO 300 mg once daily + BINI 45 mg twice daily + CETUX standard weekly dose. Assessments included efficacy (ORR, duration of response, time to response, PFS, and OS), safety, and tolerability. Results: Among 30 pts treated, 1 had a BRAF non-V600E mutation and is not included in the efficacy analyses. At data cutoff, the median follow-up time for survival was 18.2 mo and median exposure was 7.8 mo (range 0.5–21.4 mo). The confirmed ORR and median PFS remain unchanged from the previous report (ORR, 48% [95%CI, 29.4–67.5]; PFS, 8.0 mo [95% CI, 5.6–9.3 mo]). Mature median OS is 15.3 mo (95% CI, 9.6 mo–not reached). The triplet continues to be well-tolerated with no unexpected toxicities. The most common grade 3/4 toxicities were fatigue (13%), anemia, increases in creatine phosphokinase and/or aspartate aminotransferase, and urinary tract infections (each 10%). The rate of grade 3/4 skin toxicities continues to be lower than generally observed with CETUX in mCRC. Conclusions: With longer follow-up, triplet therapy with ENCO + BINI + CETUX continues to be well tolerated. Median PFS and now mature median OS are substantially improved over historical data for current standard-of-care options. Clinical trial information: NCT02928224.

Purpose To evaluate the prognostic significance of expression levels of a single microRNA, miR-181a, in the context of established molecular markers in cytogenetically normal acute myeloid leukemia (CN-AML), and to gain insight into the leukemogenic role of miR-181a. Patients and Methods miR-181a expression was measured in pretreatment marrow using Ohio State University Comprehensive Cancer Center version 3.0 arrays in 187 younger (< 60 years) adults with CN-AML. Presence of other molecular prognosticators was assessed centrally. A gene-expression profile associated with miR-181a expression was derived using microarrays and evaluated by Gene-Ontology analysis. Results Higher miR-181a expression associated with a higher complete remission (CR) rate (P = .04), longer overall survival (OS; P = .01) and a trend for longer disease-free survival (DFS; P = .09). The impact of miR-181a was most striking in poor molecular risk patients with FLT3-internal tandem duplication (FLT3-ITD) and/or NPM1 wild-type, where higher miR-181a expression associated with a higher CR rate (P = .009), and longer DFS (P < .001) and OS (P < .001). In multivariable analyses, higher miR-181a expression was significantly associated with better outcome, both in the whole patient cohort and in patients with FLT3-ITD and/or NPM1 wild-type. These results were also validated in an independent set of older (≥ 60 years) patients with CN-AML. A miR-181a-associated gene-expression profile was characterized by enrichment of genes usually involved in innate immunity. Conclusion To our knowledge, we provide the first evidence that the expression of a single microRNA, miR-181a, is associated with clinical outcome of patients with CN-AML and may refine their molecular risk classification. Targeted treatments that increase endogenous levels of miR-181a might represent novel therapeutic strategies.

The 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 associ-ated 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 FLT3-ITD–associated gene-expression signature revealed overexpression of FLT3, homeobox genes (MEIS1, PBX3, HOXB3), and immunotherapeutic tar-gets (WT1, CD33) and underexpression of leukemia-associated (MLLT3, TAL1) and erythropoiesis-associated (GATA3, EPOR, ANK1, HEMGN) genes. An FLT3-ITD–associated microRNA-expression signature included overexpressed miR-155 and underexpressed miR-144 and miR-451. FLT3-ITD identifies older CN-AML patients with molecular high risk and is associated with gene- and microRNA-expression signatures that provide biologic insights for novel therapeutic approaches.

Cancer and Leukemia Group B 19808 (CALGB 19808) is the only randomized trial of a second-generation P-glycoprotein (Pgp) modulator in untreated patients with acute myeloid leukemia (AML) younger than age 60 years. We randomly assigned 302 patients to receive induction chemotherapy regimens consisting of cytosine arabinoside (Ara-C; A), daunorubicin (D), and etoposide (E), without (ADE) or with (ADEP) PSC-833 (P). The incidence of complete remission was 75% with both regimens. Reversible grade 3 and 4 liver and mucosal toxicities were significantly more common with ADEP. Therapy-related mortality was 7% and did not differ by induction arm. Excess cardiotoxicity was not seen with high doses of D in ADE. The median disease-free survival was 1.34 years in the ADE arm and 1.09 years in the ADEP arm (P = .74, log-rank test); the median overall survival was 1.86 years in the ADE arm and 1.69 years in the ADEP arm (P = .82). There was no evidence of a treatment difference within any identifiable patient subgroup. Inhibition of Pgp-mediated drug efflux by PSC-833 did not improve clinical outcomes in younger patients with untreated AML. This trial was registered at www.clinicaltrials.gov as #NCT00006363.

Purpose To 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 Methods One hundred forty-eight adults age ≥ 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. Results Patients with NPM1 mutations (56%) had higher complete remission (CR) rates (84% v 48%; P < .001) and longer disease-free survival (DFS; P = .047; 3-year rates, 23% v 10%) and overall survival (OS; P < .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 < .001) and longer DFS (P = .004) and OS (P < .001), after adjustment for other prognostic clinical and molecular variables. Unexpectedly, the prognostic impact of NPM1 mutations was mainly observed in patients ≥ 70 years. Gene- and microRNA-expression profiles associated with NPM1 mutations were similar across older patient age groups and similar to those in younger (< 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. Conclusion NPM1 mutations have favorable prognostic impact in older patients with CN-AML, especially those age ≥ 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.

Purpose To evaluate the prognostic significance of CEBPA mutations in the context of established molecular markers in cytogenetically normal (CN) acute myeloid leukemia (AML) and gain biologic insights into leukemogenesis of the CN-AML molecular high-risk subset (FLT3 internal tandem duplication [ITD] positive and/or NPM1 wild type) that has a significantly higher incidence of CEBPA mutations than the molecular low-risk subset (FLT3-ITD negative and NPM1 mutated). Patients and Methods One hundred seventy-five adults age less than 60 years with untreated primary CN-AML were screened before treatment for CEBPA, FLT3, MLL, WT1, and NPM1 mutations and BAALC and ERG expression levels. Gene and microRNA (miRNA) expression profiles were obtained for the CN-AML molecular high-risk patients. Results CEBPA mutations predicted better event-free (P = .007), disease-free (P = .014), and overall survival (P < .001) independently of other molecular and clinical prognosticators. Among patients with CEBPA mutations, 91% were in the CN-AML molecular high-risk group. Within this group, CEBPA mutations predicted better event-free (P < .001), disease-free (P = .004), and overall survival (P = .009) independently of other molecular and clinical characteristics and were associated with unique gene and miRNA expression profiles. The major features of these profiles were upregulation of genes (eg, GATA1, ZFPM1, EPOR, and GFI1B) and miRNAs (ie, the miR-181 family) involved in erythroid differentiation and downregulation of homeobox genes. Conclusion Pretreatment testing for CEBPA mutations identifies CN-AML patients with different outcomes, particularly in the molecular high-risk group, thus improving molecular risk-based classification of this large cytogenetic subset of AML. The gene and miRNA expression profiling provided insights into leukemogenesis of the CN-AML molecular high-risk group, indicating that CEBPA mutations are associated with partial erythroid differentiation.

Purpose Because both t(8;21) and inv(16) disrupt core binding factor (CBF) in acute myeloid leukemia (AML) and confer relatively favorable prognoses, these cytogenetic groups are often treated similarly. Recent studies, however, have shown different gene profiling for the two groups, underscoring potential biologic differences. Therefore, we sought to determine whether these two cytogenetic groups should also be considered separate entities from a clinical standpoint. Patients and Methods We analyzed 144 consecutive adults with t(8;21) and 168 with inv(16) treated on Cancer and Leukemia Group B front-line studies. We compared pretreatment features, probability of achieving complete remission (CR), overall survival (OS) and cumulative incidence of relapse (CIR) between the two groups. Results With a median follow-up of 6.4 years, for CBF AML as a whole, the CR rate was 88%, 5-year OS was 50% and CIR was 53%. After adjusting for covariates, patients with t(8;21) had shorter OS (hazard ratio [HR] = 1.5; P = .045) and survival after first relapse (HR = 1.7; P = .009) than patients with inv(16). Unexpectedly, race was an important predictor for t(8;21) AML, in that nonwhites failed induction more often (odds ratio = 5.7; P = .006) and had shorter OS than whites when certain secondary cytogenetic abnormalities were present. In patients with t(8;21) younger than 60 years, type of induction also correlated with relapse risk. For inv(16) AML, secondary cytogenetic abnormalities (especially +22) and male sex predicted better outcome. Conclusion When the prognostic impact of race, secondary cytogenetic abnormalities, sex, and response to salvage treatment is considered, t(8;21) and inv(16) AMLs seem to be distinct clinical entities and should be stratified and reported separately.

MLL (ALL-1) chimeric fusions and MLL partial tandem duplications (PTD) may have mechanistically distinct contributions to leukemogenesis. Acute myeloid leukemia (AML) blasts with the t(9;11)(p22; q23) express MLL-AF9 and MLL wild-type (WT) transcripts, while normal karyotype AML blasts with the MLLPTD/WT genotype express MLL PTD but not the MLL WT. Silencing of MLL WT in MLLPTD/WT blasts was reversed by DNA methyltransferase (DNMT) and histone deacetylase (HDAC) inhibitors, and MLL WT induction was associated with selective sensitivity to cell death. Reduction of MLL PTD expression induced MLL WT and reduced blast colony-forming units, supporting opposing functions for MLL PTD and MLL WT whereby the MLL PTD contributes to the leukemic phenotype via a recessive gain-of-function. The coincident suppression of the MLL WT allele with the expression of the MLL PTD allele, along with the functional data presented here, supports the hypothesis that loss of WT MLL function via monoallelic repression contributes to the leukemic phenotype by the remaining mutant allele. These data from primary AML and the pharmacologic reversal of MLL WT silencing associated with a favorable alteration in the threshold for apoptosis suggest that these patients with poor prognosis may benefit from demethylating or histone deacetylase inhibitor therapy, or both.

627 Background: The SLI of the BEACON CRC phase 3 study assessed the safety and efficacy of the combination of the BRAF inhibitor encorafenib (ENCO) + MEK inhibitor binimetinib (BINI) + anti-EGFR antibody cetuximab (CETUX) in pts with BRAFV600E-mutant mCRC after 1 or 2 prior regimens. CEA and CA19-9 are tumor markers that are widely used to monitor the effectiveness of systemic therapies for mCRC; here we report on the association of CEA and CA19-9 changes while on treatment with clinical outcomes in pts from the SLI. Methods: Pts in the SLI received the triplet of ENCO 300 mg QD + BINI 45 mg BID + CETUX 400 mg/m2 (initial dose) then 250 mg/m2 QW in 28-day cycles. Pts were evaluated for safety, radiographic response, and change in tumor markers CEA and CA19-9. Results: 30 pts were treated. The triplet was generally well tolerated, and adverse events were consistent with known BRAF, MEK, and EGFR inhibitor toxicities. The rate of severe skin toxicities (grade 3/4) was lower than generally observed for CETUX in mCRC. Of the 29 pts with a BRAFV600E mutation, the median time on study treatment was 5.6 mo (range, 1.0–9.3 mo), and 22 (76%) remained on study treatment at the time of data cutoff. The confirmed overall response rate (ORR) was 41%, with 1 complete and 11 partial responses. In addition, 9 pts had prolonged stable disease (SD) up to 9.3 mo.CEA and CA19-9 were analyzed in 28 pts. CEA and CA19-9 decreased in 96% and 82% of these pts, respectively. Among 15 pts with treatment duration ≥5.6 mo, median/mean % decreases were 97%/79% for CEA and 92%/82% for CA19-9 in confirmed responders (n=6). Respective decreases in pts with prolonged SD (n=9) were similar: 84%/68% for CEA and 89%/68% for CA19-9. Updated safety, efficacy, and tumor marker results will be provided. Conclusions: ENCO + BINI + CETUX is generally well tolerated and has encouraging clinical activity in BRAFV 600E mCRC, with a confirmed ORR of 41%. In pts with study treatment duration ≥5.6 mo, the tumor markers CEA and CA19-9 decreased markedly and to the same degree in responders vs pts with prolonged SD, providing additional evidence of the meaningful clinical activity of this regimen. Clinical trial information: NCT02928224.

Current treatments for acute myeloid leukemia (AML) are designed to target rapidly dividing blast populations with limited success in eradicating the functionally distinct leukemia stem cell (LSC) population, which is postulated to be responsible for disease resistance and relapse. We have previously reported high miR-126 expression levels to be associated with a LSC-gene expression profile. Therefore, we hypothesized that miR-126 contributes to “stemness” and is a viable target for eliminating the LSC in AML. Here we first validate the clinical relevance of miR-126 expression in AML by showing that higher expression of this microRNA (miR) is associated with worse outcome in a large cohort of older (≥60 years) cytogenetically normal AML patients treated with conventional chemotherapy. We then show that miR-126 overexpression characterizes AML LSC-enriched cell subpopulations and contributes to LSC long-term maintenance and self-renewal. Finally, we demonstrate the feasibility of therapeutic targeting of miR-126 in LSCs with novel targeting nanoparticles (NP) containing antagomiR-126 resulting in in vivo reduction of LSCs likely by depletion of the quiescent cell subpopulation. Our findings suggest that by targeting a single miR, i.e., miR-126, it is possible to interfere with LSC activity, thereby opening potentially novel therapeutic approaches to treat AML patients.

TPS3622 Background: BRAF mutations are found in ≈10% of mCRC cases. Pts with BRAFV600E mCRC have a poor prognosis, with shorter progression-free survival (PFS) and overall survival (OS) than pts with BRAFwt mCRC (Van Cutsem et al 2011; Modest et al 2012; Sorbye et al 2015). The benefits of combined BRAF + EGFR inhibition in mCRC have been demonstrated in vitro (Corcoran et al 2012; Prahallad et al 2012; Yang et al 2012), and preclinical evidence suggests that adding MEK signaling inhibition improves antitumor activity. Early clinical data indicate that BRAF + EGFR + MEK inhibition has greater activity than BRAF + EGFR inhibition in pts with BRAFV600E mCRC (Van Cutsem et al 2016). Our study will examine the combination of BINI (a MEK inhibitor) + ENCO (a selective BRAF kinase inhibitor) + CTX (an anti-EGFR antibody) and of ENCO + CTX in pts with BRAFV600E mCRC. Methods: BEACON CRC (NCT02928224) is enrolling pts with BRAFV600E mCRC whose disease has progressed after 1 or 2 prior regimens in the metastatic setting. A safety lead-in phase (≈30 pts) will determine the safety and tolerability of oral ENCO 300 mg QD + oral BINI 45 mg BID + intravenous CTX 400 mg/m2 followed by 250 mg/m2 QW. In the phase 3 portion, ≈615 pts will be randomized 1:1:1 to triplet (ENCO + BINI + CTX), doublet (ENCO + CTX), or control (investigator’s choice of IRI/CTX or FOLFIRI/CTX) arms. Pts will be treated in 28-day cycles until disease progression, unacceptable toxicity, withdrawal of consent, initiation of subsequent anticancer therapy, or death. The primary endpoint is OS (triplet vs control). Secondary endpoints include OS (doublet vs control), confirmed investigator-assessed objective response rate according to RECIST version 1.1 (triplet or doublet vs control; triplet vs doublet), PFS (triplet or doublet vs control), duration of response, time to response, pharmacokinetics, and pt-reported outcomes. Safety will be summarized using standard adverse event reporting. Clinical trial information: NCT02928224.

9519 Background: Simultaneous inhibition of MEK and CDK4/6 may suppress MAPK pathway activation and cell-cycle checkpoint dysregulation in NRAS-mutant melanoma, resulting in enhanced antitumor activity. Phase 1b data are reported. Methods: The phase 1b primary objective was to determine maximum tolerated dose (MTD)/RP2D. A 28-d cycle of oral ribociclib (RIBO) once daily (QD) for 21 d + oral binimetinib (BINI) twice daily (BID) for 28 d, and a 21-d cycle of RIBO QD + BINI BID, both for 14 d per cycle, were evaluated. Secondary objectives were to evaluate efficacy, safety and pharmacodynamics. Results: Based on dose escalation (van Herpen, ESMO 2015), MTD was 600mg RIBO/45mg BINI for the 21-d and 200/45 for the 28-d regimens. Due to promising activity, the 28-d cycle was selected as RP2D(unconfirmed partial response [PR] with limited follow-up occurred in 35% of pts). This finding was supported by comparable and manageable safety and the Bayesian logistic regression model.As of Jan 2017, the RP2D was received by 16 pts in phase 1b (ECOG PS 0/1/2, 63%/31%/6%; elevated lactate dehydrogenase, 44%; stage IVM1c disease, 50%; prior ipilimumab [ipi], 44%; prior anti–programmed death [PD]-1/PD-L1, 31%). Median (range) exposure was 4 (0–13) mo. Common adverse events (AEs) were increased blood creatine phosphokinase, elevated AST, peripheral edema, acneiform dermatitis, diarrhea and fatigue. Common grade 3/4 AEs were elevated AST and ALT (19%/6%), nausea (19%/0%), rash (19%/0%), vomiting (6%/6%) and neutropenia (12%/0%). Confirmed PR (cPR) occurred in 4 pts (25%; time to response, 48–168 d), stable disease in 7 pts (44%), disease progression in 3 pts (19%); 2 pts (12%) were not evaluable. Among cPR pts, 3 had prior ipi and/or anti–PD-1/PD-L1. Median progression-free survival (mPFS) was 6.7 (95% CI, 3.5–9.2) mo. Sequence analysis of synchronous non- RAS genetic alterations will be presented. Conclusions: Combined RIBO/BINI at the selected RP2D had a manageable safety profile and favorable efficacy (based on mPFS) for NRAS-mutant melanoma in phase 1b. Based on these promising data, the phase 2 expansion is underway to assess antitumor activity at the RP2D. Clinical trial information: NCT01781572.

Background The purpose of this study is to determine whether microRNA for pluripotent stem cells are also expressed in breast cancer and are associated with metastasis and outcome. Methods We studied global microRNA profiles during differentiation of human embryonic stem cells (n =26) and in breast cancer patients (n = 33) and human cell lines (n = 35). Using in situ hybridization, we then investigated MIR302 expression in 318 untreated breast cancer patients (test cohort, n = 22 and validation cohort, n = 296). In parallel, using next-generation sequencing data from breast cancer patients (n = 684), we assessed microRNA association with stem cell markers. All statistical tests were two-sided. Results In healthy tissues, the MIR302 (high)/MIR203 (low) asymmetry was exclusive for pluripotent stem cells. MIR302 was expressed in a small population of cancer cells within invasive ductal carcinoma, but not in normal breast (P < .001). Furthermore, MIR302 was expressed in the tumor cells together with stem cell markers, such as CD44 and BMI1. Conversely, MIR203 expression in 684 breast tumors negatively correlated with CD44 (Spearman correlation, Rho = -0.08, P = .04) and BMI1 (Rho = -0.11, P = .004), but positively correlated with differentiation marker CD24 (Rho = 0.15, P < .001). Primary tumors with lymph node metastasis had cancer cells showing scattered expression of MIR302 and widespread repression of MIR203. Finally, overall survival was statistically significantly shorter in patients with MIR302-positive cancer cells (P = .03). Conclusions In healthy tissues the MIR302(high)/MIR203(low) asymmetry was characteristic of embryonic and induced pluripotency. In invasive ductal carcinoma, the MIR302/MIR203 asymmetry was associated with stem cell markers, metastasis, and shorter survival.

Prognostic gene mutations and distinct gene- and microRNA-expression signatures in acute myeloid leukemia with a sole trisomy 8

Purpose Cytogenetically normal (CN) acute myeloid leukemia (AML) is the largest and most heterogeneous cytogenetic AML subgroup. For the practicing clinician, it is difficult to summarize the prognostic information of the growing number of clinical and molecular markers. Our purpose was to develop a widely applicable prognostic model by combining well-established pretreatment patient and disease characteristics. Patients and Methods Two prognostic indices for CN-AML (PINA), one regarding overall survival (OS; PINAOS) and the other regarding relapse-free survival (RFS; PINARFS), were derived from data of 572 patients with CN-AML treated within the AML Cooperative Group 99 study ( www.aml-score.org ). Results On the basis of age (median, 60 years; range, 17 to 85 years), performance status, WBC count, and mutation status of NPM1, CEBPA, and FLT3-internal tandem duplication, patients were classified into the following three risk groups according to PINAOS and PINARFS: 29% of all patients and 32% of 381 responding patients had low-risk disease (5-year OS, 74%; 5-year RFS, 55%); 56% of all patients and 39% of responding patients had intermediate-risk disease (5-year OS, 28%; 5-year RFS, 27%), and 15% of all patients and 29% of responding patients had high-risk disease (5-year OS, 3%; 5-year RFS, 5%), respectively. PINAOS and PINARFS stratified outcome within European LeukemiaNet genetic groups. Both indices were confirmed on independent data from Cancer and Leukemia Group B/Alliance trials. Conclusion We have developed and validated, to our knowledge, the first prognostic indices specifically designed for adult patients of all ages with CN-AML that combine well-established molecular and clinical variables and that are easily applicable in routine clinical care. The integration of both clinical and molecular markers could provide a basis for individualized patient care through risk-adapted therapy of CN-AML.

The inv(16)(p13q22)/t(16;16)(p13;q22) in acute myeloid leukemia results in multiple CBFB-MYH11 fusion transcripts, with type A being most frequent. The biologic and prognostic implications of different fusions are unclear. We analyzed CBFB-MYH11 fusion types in 208 inv(16)/t(16;16) patients with de novo disease, and compared clinical and cytogenetic features and the KIT mutation status between type A (n = 182; 87%) and non–type A (n = 26; 13%) patients. At diagnosis, non–type A patients had lower white blood counts (P = .007), and more often trisomies of chromosomes 8 (P = .01) and 21 (P < .001) and less often trisomy 22 (P = .02). No patient with non–type A fusion carried a KIT mutation, whereas 27% of type A patients did (P = .002). Among the latter, KIT mutations conferred adverse prognosis; clinical outcomes of non–type A and type A patients with wild-type KIT were similar. We also derived a fusion-type–associated global gene-expression profile. Gene Ontology analysis of the differentially expressed genes revealed—among others—an enrichment of up-regulated genes involved in activation of caspase activity, cell differentiation and cell cycle control in non–type A patients. We conclude that non–type A fusions associate with distinctclinical and genetic features, including lack of KIT mutations, and a unique gene-expression profile.

Purpose To evaluate the prognostic significance of the international European LeukemiaNet (ELN) guidelines for reporting genetic alterations in acute myeloid leukemia (AML). Patients and Methods We analyzed 1,550 adults with primary AML, treated on Cancer and Leukemia Group B first-line trials, who had pretreatment cytogenetics and, for cytogenetically normal patients, mutational status of NPM1, CEBPA, and FLT3 available. We compared complete remission (CR) rates, disease-free survival (DFS), and overall survival (OS) among patients classified into the four ELN genetic groups (favorable, intermediate-I, intermediate-II, adverse) separately for 818 younger (age < 60 years) and 732 older (age ≥ 60 years) patients. Results The percentages of younger versus older patients in the favorable (41% v 20%; P < .001), intermediate-II (19% v 30%; P < .001), and adverse (22% v 31%; P < .001) genetic groups differed. The favorable group had the best and the adverse group the worst CR rates, DFS, and OS in both age groups. Both intermediate groups had significantly worse outcomes than the favorable but better than the adverse group. Intermediate-I and intermediate-II groups in older patients had similar outcomes, whereas the intermediate-II group in younger patients had better OS but not better CR rates or DFS than the intermediate-I group. The prognostic significance of ELN classification was confirmed by multivariable analyses. For each ELN group, older patients had worse outcomes than younger patients. Conclusion 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 DNMT3A mutations, their associations with clinical and molecular characteristics and outcome, and the associated gene- and microRNA-expression signatures in primary cytogenetically normal acute myeloid leukemia (CN-AML). Patients and Methods Four hundred fifteen previously untreated adults were analyzed for DNMT3A mutations and established prognostic gene mutations and expression markers. Gene- and microRNA-expression profiles were derived using microarrays. Results Younger (< 60 years; n = 181) and older (≥ 60 years; n = 234) patients had similar frequencies of DNMT3A mutations (35.3% v 33.3%). Missense mutations affecting arginine codon 882 (R882-DNMT3A) were more common (n = 92; 62%) than those affecting other codons (non–R882-DNMT3A). DNMT3A-mutated patients did not differ regarding complete remission rate, but had shorter disease-free survival (DFS; P = .03) and, by trend, overall survival (OS; P = .07) than DNMT3A–wild-type patients. In multivariable analyses, DNMT3A mutations remained associated with shorter DFS (P = .01), but not with shorter OS. When analyzed separately, the two DNMT3A mutation types had different significance by age group. Younger patients with non–R882-DNMT3A mutations had shorter DFS (P = .002) and OS (P = .02), whereas older patients with R882-DNMT3A mutations had shorter DFS (P = .005) and OS (P = .002) after adjustment for other clinical and molecular prognosticators. Gene- and microRNA-expression signatures did not accurately predict DNMT3A mutational status. Conclusion DNMT3A mutations are frequent in CN-AML, and their clinical significance seems to be age dependent. DNMT3A-R882 mutations are associated with adverse prognosis in older patients, and non–R882-DNMT3A mutations are associated with adverse prognosis in younger patients. Low accuracy of gene- and microRNA-expression signatures in predicting DNMT3A mutation status suggested that the role of these mutations in AML remains to be elucidated.

The alleles of the Wilms tumor 1 (WT1) polymorphism rs16754 harbor adenine (A) or guanine (G). Recently, rs16754 has been reported to affect the outcome of patients with cytogenetically normal acute myeloid leukemia. To validate this finding, we investigated pretreatment features and outcome associated with rs16754 in a large cohort of patients with cytogenetically normal acute myeloid leukemia.Four-hundred and thirty-three intensively treated and molecularly characterized cytogenetically normal patients with de novo acute myeloid leukemia (18-83 years old) were analyzed for rs16754. To gain biological insights, we studied the gene- and microRNA-expression profiles for associations with rs16754.Three-hundred and nine (71%) patients were homozygous for A (WT1(AA)), 112 (26%) were heterozygous (WT1(AG)) and 12 (3%) were homozygous for G (WT1(GG)). For comparison with previous studies, we grouped WT1(AG) and WT1(GG) patients and compared them with WT1(AA) patients divided into younger (60 years) and older (≥60 years) adults. We found no independent prognostic impact of WT1(AA). However, WT1(GG) patients, who were less often Caucasian than WT1(AG) (P=0.001) or WT1(AA) (P=0.008) patients, and had TET2 mutations more often than WT1(AG) (P=0.02) patients, had, among patients with FLT3-internal tandem duplication and/or NPM1 wild-type, better disease-free (P=0.02) and overall survival (P=0.04) than WT1(AA) and WT1(AG) patients combined. Unsupervised and supervised analyses of the gene- and microRNA-expression profiles suggested that there were no distinct expression patterns associated with any rs16754 genotype.We did not observe the previously reported adverse impact of WT1(AA) but found favorable outcomes associated with the homozygous WT1(GG). Considering its low frequency, confirmatory studies are necessary. The biological significance of rs16754 remains questionable as no distinct expression profiles were associated with the genotypes.

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

We previously reported the adverse prognostic impact of Wilms tumor 1 gene (WT1) mutations in younger adult cytogenetically normal acute myeloid leukemia (CN-AML). Here, we investigated 243 older (≥ 60 years) primary CN-AML patients. WT1 mutated (WT1mut) patients (7%) had FLT3-ITD more frequently (P < .001), lower hemoglobin (P = .01), higher white blood cell count (P = .03) and percentage blood blasts (P = .03), and a shorter overall survival (P = .08) than WT1 wild-type (WT1wt) patients. Comparing older and younger WT1mut patients, they had similar pretreatment characteristics and outcome. By contrast, among WT1wt CN-AML, younger patients had a significantly better outcome. A WT1 mutation-associated gene-expression signature, reported here for the first time, included CD96, a leukemia stem cell-specific marker, and genes involved in gene regulation (eg, MLL, PML, and SNRPN) and in proliferative and metabolic processes (eg, INSR, IRS2, and PRKAA1), supporting the role of mutated WT1 in deregulating multiple homeostatic processes. Our results indicate that WT1mut CN-AML represents a distinct entity with poor treatment response across age groups. This study has been registered at www.clinicaltrials.gov as #NCT00900224.

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.

Item does not contain fulltext The GFI1 gene encodes a transcriptional repressor, which regulates myeloid differentiation. In the mouse, Gfi1 deficiency causes neutropenia and an accumulation of granulomonocytic precursor cells that is reminiscent of a myelodysplastic syndrome. We report here that a variant allele of GFI1 (GFI1(36N)) is associated with acute myeloid leukemia (AML) in white subjects with an odds ratio of 1.6 (P < 8 x 10(-5)). The GFI1(36N) variant occurred in 1806 AML patients with an allele frequency of 0.055 compared with 0.035 in 1691 healthy control patients in 2 independent cohorts. We observed that both GFI1 variants maintain the same activity as transcriptional repressors but differ in their regulation by the AML1/ETO (RUNX1/RUNX1T1) fusion protein produced in AML patients with a t(8;21) translocation. AML1/ETO interacts and colocalizes with the more common GFI1(36S) form in the nucleus and inhibits its repressor activity. However, the variant GFI1(36N) protein has a different subnuclear localization than GFI1(36S). As a consequence, AML1/ETO does not colocalize with GFI1(36N) and is unable to inhibit its repressor activity. We conclude that both variants of GFI1 differ in their ability to be regulated by interacting proteins and that the GFI1(36N) variant form exhibits distinct biochemical features that may confer a predisposition to AML.

Purpose To determine the prognostic importance of the meningioma 1 (MN1) gene expression levels in the context of other predictive molecular markers, and to derive MN1 associated gene– and microRNA–expression profiles in cytogenetically normal acute myeloid leukemia (CN-AML). Patients and Methods MN1 expression was measured in 119 untreated primary CN-AML adults younger than 60 years by real-time reverse-transcriptase polymerase chain reaction. Patients were also tested for FLT3, NPM1, CEBPA, and WT1 mutations, MLL partial tandem duplications, and BAALC and ERG expression. Gene- and microRNA-expression profiles were attained by performing genome-wide microarray assays. Patients were intensively treated on two first-line Cancer and Leukemia Group B clinical trials. Results Higher MN1 expression associated with NPM1 wild-type (P < .001), increased BAALC expression (P = .004), and less extramedullary involvement (P = .01). In multivariable analyses, higher MN1 expression associated with a lower complete remission rate (P = .005) after adjustment for WBC; shorter disease-free survival (P = .01) after adjustment for WT1 mutations, FLT3 internal tandem duplications (FLT3-ITD), and high ERG expression; and shorter survival (P = .04) after adjustment for WT1 and NPM1 mutations, FLT3-ITD, and WBC. Gene- and microRNA-expression profiles suggested that high MN1 expressers share features with high BAALC expressers and patients with wild-type NPM1. Higher MN1 expression also appears to be associated with genes and microRNAs that are active in aberrant macrophage/monocytoid function and differentiation. Conclusion MN1 expression independently predicts outcome in CN-AML patients. The MN1 gene- and microRNA-expression signatures suggest biologic features that could be exploited as therapeutic targets.

Purpose RAS mutations occur in 12% to 27% of patients with acute myeloid leukemia (AML) and enhance sensitivity to cytarabine in vitro. We examined whether RAS mutations impact response to cytarabine in vivo. Patients and Methods One hundred eighty-five patients with AML achieving complete remission on Cancer and Leukemia Group B study 8525 and randomly assigned to one of three doses of cytarabine postremission were screened for RAS mutations. We assessed the impact of cytarabine dose on cumulative incidence of relapse (CIR) of patients with (mutRAS) and without (wild-type; wtRAS) RAS mutations. Results Thirty-four patients (18%) had RAS mutations. With 12.9 years median follow-up, the 10-year CIR was similar for mutRAS and wtRAS patients (65% v 73%; P = .31). However, mutRAS patients receiving high-dose cytarabine consolidation (HDAC; 3 g/m2 every 12 hours on days 1, 3, and 5 or 400 mg/m2/d × 5 days) had the lowest 10-year CIR, 45%, compared with 68% for wtRAS patients receiving HDAC and 80% and 100%, respectively, for wtRAS and mutRAS patients receiving low-dose cytarabine (LDAC; 100 mg/m2/d × 5 days; overall comparison, P < .001). Multivariable analysis revealed an interaction of cytarabine dose and RAS status (P = .06). After adjusting for this interaction and cytogenetics (core binding factor [CBF] AML v non-CBF AML), wtRAS patients receiving HDAC had lower relapse risk than wtRAS patients receiving LDAC (hazard ratio [HR] = 0.67; P = .04); however, mutRAS patients receiving HDAC had greater reduction in relapse risk (HR = 0.28; P = .002) compared with mutRAS patients treated with LDAC. Conclusion AML patients carrying mutRAS benefit from higher cytarabine doses more than wtRAS patients. This seems to be the first example of an activating oncogene mutation favorably modifying response to higher drug doses in AML.

Purpose To analyze the prognostic impact of Wilms’ tumor 1 (WT1) gene mutations in cytogenetically normal acute myeloid leukemia (CN-AML). Patients and Methods We studied 196 adults younger than 60 years with newly diagnosed primary CN-AML, who were treated similarly on Cancer and Leukemia Group B (CALGB) protocols 9621 and 19808, for WT1 mutations in exons 7 and 9. The patients also were assessed for the presence of FLT3 internal tandem duplications (FLT3-ITD), FLT3 tyrosine kinase domain mutations (FLT3-TKD), MLL partial tandem duplications (MLL-PTD), NPM1 and CEBPA mutations, and for the expression levels of ERG and BAALC. Results Twenty-one patients (10.7%) harbored WT1 mutations. Complete remission rates were not significantly different between patients with WT1 mutations and those with unmutated WT1 (P = .36; 76% v 84%). Patients with WT1 mutations had worse disease-free survival (DFS; P < .001; 3-year rates, 13% v 50%) and overall survival (OS; P < .001; 3-year rates, 10% v 56%) than patients with unmutated WT1. In multivariable analyses, WT1 mutations independently predicted worse DFS (P = .009; hazard ratio [HR] = 2.7) when controlling for CEBPA mutational status, ERG expression level, and FLT3-ITD/NPM1 molecular-risk group (ie, FLT3-ITDnegative/NPM1mutated as low risk v FLT3-ITDpositive and/or NPM1wild-type as high risk). WT1 mutations also independently predicted worse OS (P < .001; HR = 3.2) when controlling for CEBPA mutational status, FLT3-ITD/NPM1 molecular-risk group, and white blood cell count. Conclusion We report the first evidence that WT1 mutations independently predict extremely poor outcome in intensively treated, younger patients with CN-AML. Future trials should include testing for WT1 mutations as part of molecularly based risk assessment and risk-adapted treatment stratification of patients with CN-AML.

A role of microRNAs in cancer has recently been recognized. However, little is known about the role of microRNAs in acute myeloid leukemia (AML).Using microRNA expression profiling, we studied samples of leukemia cells from adults under the age of 60 years who had cytogenetically normal AML and high-risk molecular features--that is, an internal tandem duplication in the fms-related tyrosine kinase 3 gene (FLT3-ITD), a wild-type nucleophosmin (NPM1), or both. A microRNA signature that was associated with event-free survival was derived from a training group of 64 patients and tested in a validation group of 55 patients. For the latter, a microRNA compound covariate predictor (called a microRNA summary value) was computed on the basis of weighted levels of the microRNAs forming the outcome signature.Of 305 microRNA probes, 12 (including 5 representing microRNA-181 family members) were associated with event-free survival in the training group (P0.005). In the validation group, the microRNA summary value was inversely associated with event-free survival (P=0.03). In multivariable analysis, the microRNA summary value remained associated with event-free survival (P=0.04) after adjustment for the allelic ratio of FLT3-ITD to wild-type FLT3 and for the white-cell count. Using results of gene-expression microarray analysis, we found that expression levels of the microRNA-181 family were inversely correlated with expression levels of predicted target genes encoding proteins involved in pathways of innate immunity mediated by toll-like receptors and interleukin-1beta.A microRNA signature in molecularly defined, high-risk, cytogenetically normal AML is associated with the clinical outcome and with target genes encoding proteins involved in specific innate-immunity pathways.

Background Cytogenetically normal acute myeloid leukemia (CN-AML) is the largest and most heterogeneous cytogenetic AML subgroup. For the practicing clinician it is difficult to know how to use the prognostic information of the growing number of clinical and molecular markers. Our purpose was to develop a widely applicable prognostic model by combining well-established pre-treatment patient and molecular characteristics. Patients and methods Two prognostic indices for CN-AML, one with regard to overall survival (PINAOS) and the other regarding relapse-free survival (PINARFS) were derived based on a cohort of 669 CN-AML patients treated within the AML Cooperative Group 99 (AMLCG99) study. Results Based on age (median: 60 years [range: 17-85 years]), performance status, white blood count, and presence or absence of NPM1 mutation, biallelic CEBPA mutation, and FLT3-ITD, patients were classified into three risk groups according to PINAOS and PINARFS: 29% of all and 32% of responding patients had low risk (5-year OS 72%; 5-year RFS 55%), 56% and 39% intermediate risk (5-year OS 28%; 5-year RFS 27%), and 15% and 29% high risk disease (5-year OS 3%; 5-year RFS 8%) (Figure 1). PINAOS and PINARFS further subdivided the European LeukemiaNet (ELN) favorable-genetic group as well as the ELN intermediate-I-genetic group. Both, PINAOS and PINARFS were confirmed in a large, independent, and comparable CN-AML cohort of 529 patients from the Cancer and Leukemia Group B (CALGB/Alliance) trials (Figure 2). Conclusions We have developed and validated the first prognostic indices specifically designed for CN-AML patients of all ages combining well-established molecular and clinical variables easily applicable in routine clinical care. The integration of both clinical and molecular markers could provide a basis for individualized patient care by risk-adapted therapy of CN-AML. Disclosures: No relevant conflicts of interest to declare.

1387 [][1] miR-155 is upregulated in aggressive subtypes of solid tumors and leukemia. In AML, higher miR-155 expression is associated with FLT3 -ITD. However, whether miR-155 upregulation impacts on clinical outcome independently from FLT3 -ITD and other prognosticators is unknown. We evaluated the prognostic impact of miR-155 in 363 CN-AML pts (153 age ( (

Abstract 1293 Receptor tyrosine kinases (RTKs) constitutively activated by gene mutation, overexpression and/or autocrine activation via ligand expression have been shown to negatively impact on outcomes of AML patients (pts). AXL, a member of the TAM (TYRO3, AXL, MERTK) RTK gene family was reported to be overexpressed and associated with poor survival in AML (Rochlitz, et al, Leukemia, 1999: 13:1352–8). No AXL mutations have been described, suggesting its activation may occur via aberrant expression in leukemic blasts of a TAM RTK ligand, GAS6. GAS6 was shown to be overexpressed in AML (Dirks, et al Leuk. Res. 23:643–51); yet its prognostic relevance is unknown. We report clinical and molecular associations and prognostic impact of aberrant GAS6 expression, in the context of TAM RTKs and known prognostic markers in de novo CN-AML pts (n=270; aged 18–83 y) treated with cytarabine/anthracycline-based therapies. Sixty-nine (26%) pts expressed GAS6 (>background signal; derived from microarray gene expression profiles of AML samples). TYRO3 expression status [positive (+) vs negative (–)] was similar in GAS6+ and GAS6– pts (P=.74), while AXL+ (P Table. MVA models Variable CR DFS OS EFS P OR (95% CI) P HR (95% CI) P HR (95% CI) P HR (95% CI) GAS6 expression, + v – .02 0.46 (0.24, 0.88) .03* 1.78 (1.07, 2.96) .05* 1.59 (1.00, 2.52) .03* 1.59 (1.06, 2.41) NPM1, mut v wt .001 2.97 (1.53, 5.77) – – – – .006 0.64 (0.46, 0.88) FLT3-ITD, present v absent – – .003 1.66 (1.19, 2.33) – – .005 1.55 (1.14, 2.11) WT1, mut v wt – – – – ORs > ( ( *There are interactions between GAS6 and TYRO3/AXL dual receptor status for DFS (P=.16), OS (P=.06) and EFS (P=.12). The P-values, HRs and CIs are for comparisons of GAS6+ v GAS6– pts within the TYRO3–/AXL– subset. Disclosures: No relevant conflicts of interest to declare.

Abstract 773 Altered expression of SPARC, [secreted protein, acidic, cysteine-rich (osteonectin)] a gene encoding a protein that modulates cell-matrix interactions, has been reported in cancer and leukemia, but its precise contribution to malignant transformation is unknown. We previously reported that SPARC was among the most upregulated genes in the gene-expression profile (GEP) associated with IDH2-R172 mutations (mut; Marcucci et al. JCO 2010;28:2348) and among the most downregulated genes associated with NPM1 mut (Becker et al. JCO 2010;28:596) in cytogenetically normal (CN) AML. Both mutations have strong but opposite impact (IDH2-R172 mut, adverse; NPM1 mut, favorable) on clinical outcome. Thus, we hypothesized that SPARC may act as an oncogene and contribute to AML aggressiveness. To determine functional and mechanistic activities of SPARC in AML, we conducted gain- and loss-of-function experiments in cell lines and primary blasts collected from patients under the OSU Leukemia Tissue Bank protocol. In vitro, ectopic expression and knockdown of SPARC in THP-1 and Kasumi-1 AML cells led to increase (2.5-fold P=0.03) and decrease (45%, P=0.03) in colony forming ability, respectively. Clonogenic assays in SPARC- vs empty vector (EV)-infected AML blasts also showed 2-fold increase in colony-formation (P=.01) supporting a role of SPARC overexpression in promoting leukemia growth. The leukemogenic activity of the SPARC protein was likely mediated by its binding to αvβ3 integrin and in turn by the activation of the kinase ILK. This induced GSK3β phosphorylation (p) and in turn activation of β-catenin, previously reported to contribute to AML. Indeed, while ILK knockdown abolished SPARC-induced p-GSK3β, ectopic SPARC expression led to a 4-fold increased p-GSK3β, measured by p-GSK3β (Ser-9) immunoblot assay, and to stabilization of β-catenin, measured by p-β-catenin(Ser-552) and p-β-catenin(Ser-675) immunoblot assays in AML blasts. As a result, we observed increase in translocation of β-catenin to the nucleus in SPARC overexpressing cells by confocal microscopy. Nuclear β-catenin led to increased activity of the TCF/LEF transcription factors as shown by a TCF/LEF luciferase reporter assay (5.8-fold, P The results in the preclinical models prompted us to evaluate whether higher SPARC expression associated with aggressive human disease. Thus, SPARC expression levels were measured by NanoString nCounter assay in a cohort of CN-AML patients (pts; n=362; age, 18–83 years) comprehensively characterized for mutations in the NPM1, FLT3, CEBPA, WT1, TET2, MLL, IDH1, IDH2, RUNX1, ASXL1 and DNMT3A genes, and treated with cytarabine-anthracycline based regimens. Higher SPARC expressers were more likely classified in the European Leukemia Net (ELN) Intermediate-I (CEBPA wt, NPM1 mut with FLT3-ITD, or NPM1 wt) than the ELN Favorable Genetic Group (CEBPA mut and/or NPM1 mut without FLT3-ITD; P60 years); shorter DFS (P=.07), once adjusted for FLT3-ITD, RUNX1, WBC and age group; and shorter OS (P In conclusion, high SPARC expression contributes to aggressive AML growth via β-catenin activation-mediated mechanisms. SPARC overexpression independently predicted worse outcome in CN-AML pts, and may represent a potentially novel prognostic marker and therapeutic target in AML. Disclosures: No relevant conflicts of interest to declare.

Introduction: Risk-adapted therapy of AML patients (pts) is presently based on cytogenetic and molecular findings. However, the outcome remains poor for the majority of pts. Overexpression of BAALC is implicated in leukemogenesis and poor survival of CN-AML pts, but the underlying mechanisms are unknown. We hypothesized that the elevated expression of BAALC might result from a genetic variant in or close to the gene (in cis). Methods and Results: BAALC and RUNX1 expression were measured in pre-therapy samples from a test set of 253 CN-AML pts (Cancer And Leukemia Group B) using Affymetrix U133 plus 2.0 arrays. Pts were grouped as high or low BAALC and high or low RUNX1 expressers using the median expression value as the cut-off and screened for single nucleotide polymorphisms (SNPs) by direct sequencing of the BAALC gene. Nine informative SNPs were identified. By genotyping, marker rs62527607, a non-coding SNP in the promoter region correlated with high BAALC expression (rs62527607G>T: genotypes TT/GT vs. GG: P=2.01E-04). Luciferase reporter constructs (pGL4.11) spanning the respective alleles demonstrated that the T allele (“risk allele”) of rs62527607 increased luciferase activity compared to the G allele (P=1.0E-02). The T allele of rs62527607 is predicted to create a binding site for the transcription factor RUNX1. Indeed, RUNX1-cotransfection showed an increase in luciferase activity for the T allele of rs62527607 (P=2.0E-02) but not for the G allele (P=2.7E-01). An Electrophoretic Mobility Shift Assay comparing the binding activity of the two alleles showed highly increased binding activity of RUNX1 to the T allele vs. the G allele. Testing of the pt samples for a potential correlation of RUNX1 and BAALC expression levels revealed a positive correlation in pts with genotypes TT/GT but not GG when restricting the analysis to the high RUNX1 expressing group (P=1.18E-04). For validation of our findings, a set of 105 CN-AML pts comprising 52 high and 53 low BAALC expressers (AML Study Group [AMLSG], quantitative Real-Time PCR [qPCR]) was genotyped for rs62527607, determined for RUNX1 expresser status (qPCR) and analyzed alone and in combination with the test set. A non-significant association of TT/GT vs. GG with high BAALC expression (31% vs. 19%; P=1.6E-01) was seen. Analyzing both sets combined resulted in a P-value of 9.3E-05 (Odds Ratio [OR]=2.59 [1.62, 4.22; 95%CI]). Combining the results of the CALGB & AMLSG series showed a highly significant association between RUNX1 and BAALC expression in pts with genotypes TT/GT belonging to the high RUNX1 expressing group (P=7.97E-05, OR=4.02 [2.05, 8.21; 95%CI]). Conclusion: We show that the risk allele of rs62527607 creates a RUNX1 binding site, thereby leading to increased transcription of BAALC. The observation that a heritable trait is involved in the leukemogenesis process might initiate a new era of personalized medicine in AML. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1307. doi:1538-7445.AM2012-1307

Abstract 2514 Approximately 8% of de novo AML pts have inv(16)(p13q22) or t(16;16)(p13;q22) [inv(16)] and this cytogenetic group is associated with high complete remission (CR) rates and a relatively favorable outcome after cytarabine/daunorubicin (ara-c/dnr)-based induction and high-dose ara-c (HiDAC) consolidation therapy. However, ∼40% of these pts still relapse. The molecular mechanisms that impact on the prognosis of inv(16) pts remain to be fully elucidated. We and others reported that presence of the mutated KIT (mutKIT) gene is associated with worse outcome, but other contributing factors may play a role. Molecularly, inv(16) results in disruption of the MYH11 gene at 16p13 and CBFB gene at 16q22, creating a CBFB-MYH11 fusion gene. Since the genomic breakpoints within CBFB and MYH11 are variable and the fusion transcripts depend on the exons fused, at least 11 different sized CBFB-MYH11 fusion transcript variants have been found. The frequency of each fusion varies, with ∼85% being type A and ∼5% each types D and E; types B, C, and F-K were reported in single cases (hereafter we refer to non-type A fusions as “rare”). To our knowledge, only one study (Schnittger et al. Leukemia 2007;21:725) has examined the biological and clinical significance of rare CBFB-MYH11 fusions in AML. Fusion type was not found to be prognostic, but the cohort included pts with therapy-related and secondary AML. Thus, further studies are warranted. Accordingly, we analyzed 149 de novo CBFB-MYH11 positive AML pts aged Disclosures: No relevant conflicts of interest to declare.

Abstract 1462 Despite progress made in understanding the biology and risk-adapted treatment of AML, prognosis of older pts [age ≥60 years (y)] remains poor. We have shown that high expression of the BAALC gene bestows worse outcome in older CN-AML pts. Yet, the mechanism(s) by which BAALC affects response to therapy remain unknown. MicroRNAs (miRs) are small noncoding RNAs that hybridize to target mRNAs and inhibit their translation or promote degradation, resulting in downregulation of the corresponding proteins. Recently, miR-3151 was discovered embedded in intron 1 of BAALC. We thus hypothesized that miR-3151 might be co-expressed with BAALC and contributes alone or in concert with its host to poor prognostic impact in older CN-AML. MiR-3151 and BAALC expression were measured by quantitative real time (RT) PCR in pretreatment blood of 179 older CN-AML pts enrolled on Cancer and Leukemia Group B (CALGB) cytarabine/daunorubicin-based protocols. The expression values of miR-3151 and BAALC were normalized to the internal controls SNORD44 and RN18S1, respectively. MiR-3151 expression correlated only weakly with the expression of BAALC (Spearman correlation r= 0.3). For clinical and prognostic analyses pts were dichotomized into high and low miR-3151 and BAALC expressers at the median miR and gene transcript expression values and analyzed for other molecular prognosticators (FLT3 -ITD, FLT3 -TKD, CEBPA, IDH1, IDH2, NPM1, TET2, WT1 mutations and ERG expression). Gene (GEP) and microRNA (MEP) expression profiles associated with miR-3151 expression were derived, using Affymetrix U133 plus 2.0 & OSU CCC v4.0 arrays, respectively. At diagnosis, higher miR-3151 expression was associated with lower % blood blasts (P =.02), FAB types M4 and M5 (P =.05), and wild-type NPM1 (P Disclosures: No relevant conflicts of interest to declare.

Abstract 236 Altered expression of microRNAs (miRNAs, a class of small regulatory RNAs) is associated with various types of cancers, including acute myeloid leukemia (AML). We showed previously that increased expression of miR-181a with or without miR-181b was associated with a favorable prognosis for patients with cytogenetically normal AML (CN-AML). However, the prognostic value of miR-181 expression in cytogenetically abnormal AML (CA-AML) remains elusive, even though CA-AML represents the majority of human AML. To investigate the association of expression signatures of miR-181 family members and of their potential target genes with outcome in patients with primary CA-AML, we employed two independent sets of 86 CA-AML patients to investigate the association of expression signatures of miR-181 family members with outcome. We also used four independent sets of 454 CA-AML patients to identify and validate a prognostic signature of miR-181 targets. In addition, we investigated the biological functions of miR-181a/b and target(s) in leukemia cell lines and in a leukemia mouse model. As with CN-AML, we found that both miR-181a and miR-181b expression signatures are significantly (P Disclosures: No relevant conflicts of interest to declare.

Abstract 414 The ELN standardized system for reporting cytogenetic and select molecular findings was created to enable comparisons of studies correlating treatment outcome with genetic data in AML (Döhner et al. Blood 2010;115:453). The ELN classification is based on published reports on prognostic import of cytogenetic and molecular alterations, but has not been tested in large cohorts of similarly treated AML pts, except for 1 study comprising ∼20% secondary AML pts (Röllig et al. JCO 2011;29:2758). Thus our goal was to assess the prognostic utility of the ELN classification in a relatively large cohort lacking the confounding effects of AML type (de novo v secondary) or different therapies [chemotherapy v allogeneic stem cell transplant (SCT)]. We analyzed 1,550 de novo AML pts (excluding AML M3, which is not part of the ELN classification) treated with cytarabine-daunorubicin-based chemotherapy on Cancer and Leukemia Group B frontline protocols; no pt received SCT in 1st complete remission (CR). Since consolidation therapy of younger [ The pts were classified into the 4 ELN Genetic Groups: Favorable (Fav), Intermediate I (Int I), Intermediate II (Int II) or Adverse (Adv). Younger pts were classified in the Fav Group twice as often and in the Int II and Adv Groups ∼30% less often than older pts (Table 1). Within the Fav Group, core binding factor AML [t(8;21), inv(16) or t(16;16)] was twice as common (P After a median follow-up for younger and older pts alive of, respectively, 7.6 y (range, 0.6–19.1) and 6.1 y (range, 2.3–16.4), CR rates, disease-free (DFS) and overall (OS) survival differed significantly across the ELN Groups in both age groups (Table 2, Fig. 1). Pairwise comparisons between individual ELN Groups also yielded significant differences for all of them, except for the comparison between the Int I and Int II Groups, which did not show significant differences for any outcome endpoint in older pts nor for CR rates or DFS in younger pts; OS of younger Int II pts was longer than OS of Int I pts (P=.02; Fig. 2). For each ELN Group, the outcome of older pts was worse than that of younger pts. We conclude that despite differences in frequencies of younger and older pts classified into Fav, Int II and Adv ELN Groups and subsets within these Groups, the ELN classification allows prognostic grouping of both younger and older de novo AML pts. It is hoped that new markers (eg, TET2, ASXL1 mut) will improve pt classification to ELN Int I and Fav Groups.Table 2.Outcomes according to the ELN GroupsOutcomeFavInt IInt IIAdvPYounger pts, n=818n=339n=144n=156n=179 CR rate, %96767950 Disclosures: No relevant conflicts of interest to declare.

Abstract 98 Mutations in the TET2 gene were recently identified in a variety of myeloid neoplasms including AML. However, the frequency and clinical relevance of TET2 mutations in CN-AML, the largest cytogenetic subgroup of adult AML, have not been well defined. We report here the frequency and spectrum of TET2 mutations, and their associations with clinical and molecular characteristics, treatment outcomes and genome-wide gene- and microRNA (miR)-expression signatures in a relatively large cohort of 427 patients (pts) with primary CN-AML. The pts, aged 18–83 years, were intensively treated on CALGB frontline protocols, and were analyzed centrally for TET2 mutations by PCR and direct sequencing, and for other prognostic gene mutations (FLT3 internal tandem duplications [ITD] and tyrosine kinase domain mutations, MLL partial tandem duplications, and mutations in NPM1, CEBPA, WT1 and IDH1&IDH2). If available, buccal swabs or remission marrow samples were used to determine TET2 germline status. Gene- and miR-expression profiles were derived using microarrays (Affymetrix HG-U133 plus 2.0 and OSUCCC custom miR array v4.0). At least 1 sequence variation in TET2 was found in 104 pts. Frameshift (n=59) and nonsense (n=34) variations were distributed throughout all coding exons, while missense changes (n=37) clustered mainly (28/37) in 2 evolutionarily conserved domains of TET2. The remaining missense variations in 9 pts were located outside the conserved domains, and analysis of available buccal swabs or remission samples showed that these sequence changes were present in the germline. Since it is unclear whether they represent innocent polymorphisms or disease-relevant mutations, these 9 pts were excluded from further analyses. TET2-mutated (TET2-mut) pts were older (P Disclosures: No relevant conflicts of interest to declare.