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Background: The development of new genetic profiling techniques such as Next Generation Sequencing (NGS) have helped to unravel the genomic landscape of a large number of hematological diseases. In acute myeloblastic leukemia (AML), many mutations have been found at diagnosis or during the course of the disease, either alone or in combination. Nevertheless, the clinical significance of most of them has not been well established. That is particularly true regarding infrequent gene mutations and their co-mutations as they are underrepresented in most case series that have been analyzed so far. The big data platform of HARMONY alliance provides the excellent basis for addressing this problem as it assimilates clinical and genomic information about AML patients from over 100 organisations in 18 European countries comprising more than 5000 patients. Anonymised and harmonized using OMOP standards, data collected in HARMONY are optimal for studying the impact of gene-gene-interactions overcoming differences related to data providers. Aims: To identify clinically significant genetic patterns of 2 or more concurrent mutations using the Harmony alliance AML database Methods: From the HARMONY alliance database, we selected ~3600 AML patients with NGS molecular panel analysis. We first performed survival analysis between each gene combination and then we rendered those with statistically significant differences in one easy-to-read graph using the Gephi platform (Fig. A). We then highlighted promising or unexpected associations and analyzed them one by one in greater detail. Finally, these results were validated on an independent cohort. Results: We found that the co-mutation of RAD21 (RAD21mut) in DNMT3A mutated (DNMT3Amut) AML impacted outcome compared to DNMT3Amut alone patients (Fig. B, 3-year survival, 81% vs 52%, p=0.016). However, this effect was exclusively seen in allogeneic transplant recipients. In order to identify possible bias that could be generated if RAD21mut were associated with other well-known favorable prognosis mutations, we compared the frequency of each mutation in our DNMT3Amut / RAD21mut subgroup with the global AML cohort. NPM1 co-mutation was more frequent in the DNMT3Amut / RAD21mut group (Fig. C 3, 84% of patients with NPM1 mutation (NPM1mut) vs 26% in the global cohort), potentially explaining the higher survival. Next, we tried to isolate the positive effect of NPM1 on outcome by comparing DNMT3Amut / NPM1mut patients with and without the RAD21 co-mutation. This analysis showed a favorable outcome only in RAD21mut patients compared to RAD21 wildtype (Fig. D, 3-year survival, 83% in RAD21mut / DNMT3Amut / NPM1mut vs 50% in DNMT3Amut / NPM1mut with RAD21 wildtype, p=0.016), one more time only in allogeneic transplant recipients. Finally in order to validate our results we reproduced this study from the beginning using an independent cohort of 3125 AML patients. The Gephi graph confirmed an association of DNMT3Amut / RAD21mut patients with better survival over DNMT3A alone (3 year-survival, 75% vs 37%, p Conclusions: Using the HARMONY alliance database we tested for potential gene co-mutations in AML patients, often very infrequently represented in other studies. Our data suggest that RAD21mut has a positive effect on outcome in patients receiving an allogeneic transplant with concurrent mutation of DNMT3A and NPM1. Even though NPM1mut is much more frequent in the DNMT3Amut / RAD21mut group, its association with favourable outcome seems to depend on the presence of an additional RAD21mut Keywords: AML , gene combinations, RAD21, DNMT3A, NPM1, HARMONY, big data. Figure: Graphical results. A. View obtained from the Gephi platform with the gene combinations and their effect on survival. B. Survival curves respectively of the DNMT3A+RAD21 cohort and the DNMT3A-only one. 1. Representation of the proportions of each mutation in the overall cohort (red) compared to the DNMT3A+RAD21 cohort (blue). D. Survival curves respectively of the NPM1+DNMT3A+RAD21 cohort and the NPM1+DNMT3A one. Figure 1 Figure 1. Disclosures Sobas: Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Heckman: Novartis: Research Funding; Orion Pharma: Research Funding; Celgene/BMS: Research Funding; Oncopeptides: Consultancy, Research Funding; Kronos Bio, Inc.: Research Funding. Ayala: Incyte Corporation: Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria; Celgene: Honoraria. Dombret: Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Servier: Research Funding; Abbvie: Honoraria; Daiichi Sankyo: Honoraria; BMS-Celgene: Honoraria. Sierra: Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Jazz Pharmaceuticals: Research Funding; Novartis: Honoraria, Research Funding, Speakers Bureau; BMS Celgene: Honoraria, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Honoraria; Roche: Other: Educational grant; Janssen: Other: Educational grant; Amgen: Other: Educational grant; Alexion: Other: Educational grant. Mayer: Principia: Research Funding. Voso: Celgene: Consultancy, Research Funding, Speakers Bureau; Novartis: Speakers Bureau. Sanz: Helsinn Healthcare: Consultancy, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Speakers Bureau; Gilead Sciences: Other: Travel, accommodations, and expenses; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Research Funding. Calado: Novartis: Current Employment. Döhner: Janssen: Honoraria, Other: Advisory Board; Jazz Roche: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Astellas: Research Funding; Agios and Astex: Research Funding; Daiichi Sankyo: Honoraria, Other: Advisory Board; Celgene/BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Gaidzik: Janssen: Speakers Bureau; Pfizer: Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Heuser: AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Membership on an entity's Board of Directors or advisory committees, Research Funding; Jazz: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm: Research Funding; BergenBio: Research Funding; BMS/Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees, Research Funding; Tolremo: Membership on an entity's Board of Directors or advisory committees; Astellas: Research Funding; Bayer Pharma AG: Research Funding. Haferlach: MLL Munich Leukemia Laboratory: Other: Part ownership. Turki: Jazz Pharma: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau; CSL Behring: Consultancy. Schulze-Rath: Bayer: Current Employment. Hernández Rivas: Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees. Bullinger: Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Bristol-Myers Squibb: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Hexal: Consultancy; Gilead: Consultancy; Abbvie: Consultancy, Honoraria; Menarini: Consultancy; Novartis: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Amgen: Honoraria; Astellas: Honoraria; Sanofi: Honoraria; Seattle Genetics: Honoraria; Bayer: Research Funding. Döhner: Jazz: Honoraria, Research Funding; Janssen: Honoraria; GEMoaB: Honoraria; Astellas: Honoraria, Research Funding; Astex: Honoraria; Agios: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding; Roche: Honoraria; Pfizer: Research Funding; Novartis: Honoraria, Research Funding; Oxford Biomedicals: Honoraria; Helsinn: Honoraria; BMS: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; AstraZeneca: Honoraria; Berlin-Chemie: Honoraria; Amgen: Honoraria, Research Funding. Ossenkoppele: Servier: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Abbvie, AGIOS, BMS/Celgene Astellas,AMGEN, Gilead,Servier,JAZZ,Servier Novartis: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Gilead: Consultancy, Honoraria.

In the international randomized phase 3 RATIFY (Randomized AML Trial In FLT3 in patients less than 60 Years old) trial, the multikinase inhibitor midostaurin significantly improved overall and event-free survival in patients 18 to 59 years of age with FLT3-mutated acute myeloid leukemia (AML). However, only 59% of patients in the midostaurin arm achieved protocol-specified complete remission (CR), and almost half of patients achieving CR relapsed. To explore underlying mechanisms of resistance, we studied patterns of clonal evolution in patients with FLT3-internal tandem duplications (ITD)-positive AML who were entered in the RATIFY or German-Austrian Acute Myeloid Leukemia Study Group 16-10 trial and received treatment with midostaurin. To this end, paired samples from 54 patients obtained at time of diagnosis and at time of either relapsed or refractory disease were analyzed using conventional Genescan-based testing for FLT3-ITD and whole exome sequencing. At the time of disease resistance or progression, almost half of the patients (46%) became FLT3-ITD negative but acquired mutations in signaling pathways (eg, MAPK), thereby providing a new proliferative advantage. In cases with FLT3-ITD persistence, the selection of resistant ITD clones was found in 11% as potential drivers of disease. In 32% of cases, no FLT3-ITD mutational change was observed, suggesting either resistance mechanisms bypassing FLT3 inhibition or loss of midostaurin inhibitory activity because of inadequate drug levels. In summary, our study provides novel insights into the clonal evolution and resistance mechanisms of FLT3-ITD–mutated AML under treatment with midostaurin in combination with intensive chemotherapy.

Background: The decision to perform allogeneic haematopoietic stem cell transplantation (alloHSCT) in acute myeloid leukemia (AML) is based on the risk-benefit ratio (non relapse mortality vs reduction of relapse risk). In 2017, the European LeukemiaNet (ELN) proposed a risk score based on cytogenetic and molecular genetic characteristics to facilitate this decision. Despite this improved classification of the genetic landscape of AML, the assessment of risk of relapse should be more precise. However, large cohorts are needed to analyze the clinical outcome of specific genetic alterations. Within the HARMONY alliance, we have now collected harmonized clinical and analytical data for a large number of AML patients. Aims: This study focuses on AML patients who achieved first complete remission (CR1) that, according to ELN risk (low/intermediate) assessment are not classical candidates for alloHSCT as consolidation therapy. The aim of this study is to create a more accurate risk prediction in this setting based on an on-line tool that can visualize the likelihood of relapse and thereby help to determine in which patient alloHSCT should be performed in CR1. Methods: The data included in the HARMONY alliance database was provided by 100 organisations in 18 European countries. In order to be accepted, they passed through quality control, anonymisation and harmonisation processes before being included in the database. Harmonisation is carried out according to the Observational Medical Outcomes Partnership (OMOP) Common Data Model (CDM), which is specially designed to accommodate both administrative claims and medical records, making it possible to bring together all the information from different data sources and to speed up its subsequent analysis. Through the analysis platform, we selected patients from the ~5700 patients available that matched the target population of the study. We filtered out those patients without sufficient information on their clinical course, those who did not achieve complete remission and patients with a poor prognosis (adverse risk according to ELN2017), as the study focuses on patients who a priori did not have an indication for alloHSCT. This process resulted in a sample of 842 patients. In the next steps, variable selection was performed together with the treatment of incomplete cases by imputation. Multiple Machine Learning (ML) techniques, both parametric and non-parametric, were tested for predictions (Random Forest, Weibull distribution), all of them taking into account censored data. Other sets of methods were applied to explain the information handled by the previous models and to present graphically, for each prediction, a breakdown of the influence that each feature had on that prediction. Validation of the results is being performed both by testing by medical specialists and by means of statistical indicators, such as Harrell's index. Results: The study population of 842 AML patients included 47% females and the median age was 49 years. The most frequent mutation was NPM1 (50%), followed by DNMT3A (31%) and NRAS (26%). The tool first displays a panel in which characteristics such as age, gender, and possible mutations and cytogenetic abnormalities are selected from a list based on information in the HARMONY database. Once the desired profile has been selected, graphical results are provided: 1). the probability of Relapse-Free Survival (RFS) over time. In parallel, as a reference, the probability of RFS of patients corresponding to each category of the ELN2017 can be seen. 2). a breakdown of the relative weight of each feature in the model at a specific time point, as well as the positive/negative effect that the presence/absence of these features has on the prognostic factor of relapse, adapting all this information in each individual simulation. This preliminary research tool can integrate new data and be expanded with new tools to provide useful results in a simple and accessible way. Conclusion: Building big data platforms, such as the HARMONY Alliance, are absolutely essential to facilitate the creation of tools to support research and ultimately clinical practice. Big data analysis should be considered a very useful field in disease research and it is necessary to share the results with easy-to-use tools that are available at all times. This new ML tool for AML aims to achieve these goals through its simple design and its implementation in mobile devices. Figure 1 Figure 1. Disclosures Sobas: Novartis: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Heckman: Kronos Bio, Inc.: Research Funding; Oncopeptides: Consultancy, Research Funding; Novartis: Research Funding; Orion Pharma: Research Funding; Celgene/BMS: Research Funding. Dombret: Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Research Funding; Pfizer: Honoraria, Research Funding; Servier: Research Funding; Abbvie: Honoraria; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. Sierra: Jazz Pharmaceuticals: Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Amgen: Other: Educational grant; BMS Celgene: Honoraria, Research Funding; Alexion: Other: Educational grant; Novartis: Honoraria, Research Funding, Speakers Bureau; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Roche: Other: Educational grant; Janssen: Other: Educational grant; Pfizer: Honoraria. Mayer: Principia: Research Funding. Voso: Celgene: Consultancy, Research Funding, Speakers Bureau; Novartis: Speakers Bureau. Sanz: Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Speakers Bureau; Gilead Sciences: Other: Travel, accommodations, and expenses; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Consultancy, Membership on an entity's Board of Directors or advisory committees; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses; Helsinn Healthcare: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Research Funding. Calado: Novartis: Current Employment. Döhner: Celgene/BMS: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria, Other: Advisory Board; Astellas: Research Funding; Jazz Roche: Consultancy, Honoraria; Agios and Astex: Research Funding; Abbvie: Consultancy, Honoraria; Janssen: Honoraria, Other: Advisory Board; Novartis: Consultancy, Honoraria, Research Funding. Gaidzik: Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Speakers Bureau; Janssen: Speakers Bureau. Heuser: Jazz Pharmaceuticals: Consultancy, Honoraria, Other: Research funding for institution; Janssen: Honoraria; Novartis: Consultancy, Honoraria, Other: Research funding for institution; Abbvie: Consultancy; BMS/Celgene: Consultancy; Daiichi Sankyo: Consultancy, Other: Research funding for institution; Pfizer: Consultancy, Other: Research funding for institution; Roche: Consultancy, Other: Research funding for institution; Tolremo: Consultancy; Astellas: Other: Research funding for institution; Bayer Pharma AG: Other: Research funding for institution; BergenBio: Other: Research funding for institution; Karyopharm: Other: Research funding for institution. Haferlach: MLL Munich Leukemia Laboratory: Other: Part ownership. Turki: CSL Behring: Consultancy; MSD: Consultancy, Speakers Bureau; Jazz Pharma: Consultancy, Speakers Bureau. Reinhardt: Astellas Pharma Inc.: Research Funding; Eusa: Other: Advisory board; Novartis: Other: Advisory board; BluebirdBio: Other: Advisory board; Janssen: Other: Advisory board; Abbvie: Other: Advisory board; JAZZ: Other: Advisory board; BMS: Other: Advisory board. Schulze-Rath: Bayer: Current Employment. Dohner: Berlin-Chemie: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; GEMoaB: Honoraria; Gilead: Honoraria; Helsinn: Honoraria; Janssen: Honoraria; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Oxford Biomedica: Honoraria; Pfizer: Research Funding; Roche: Honoraria; AstraZeneca: Honoraria; Astex Pharmaceuticals: Honoraria; Astellas: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Abbvie: Honoraria, Research Funding. Ossenkoppele: Abbvie, AGIOS, BMS/Celgene Astellas,AMGEN, Gilead,Servier,JAZZ,Servier Novartis: Consultancy, Honoraria; Agios: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; Gilead: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Jazz: Consultancy, Honoraria. Bullinger: Pfizer: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Menarini: Consultancy; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Astellas: Honoraria; Sanofi: Honoraria; Seattle Genetics: Honoraria; Bayer: Research Funding; Amgen: Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Gilead: Consultancy; Celgene: Consultancy, Honoraria; Hexal: Consultancy. Hernández-Rivas: Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding.

Summary: Over the past years growing knowledge about biological processes and pathways revealed complex interaction networks involving many genes. In order to understand these networks, analysis of differential expression has continuously moved from single genes towards the study of gene sets. Various approaches for the assessment of gene sets have been developed in the context of gene set analysis (GSA). These approaches are bridging the gap between raw measurements and semantically meaningful terms. We present a novel approach for assessing uncertainty in the definition of gene sets. This is an essential step when new gene sets are constructed from domain knowledge or given gene sets are suspected to be affected by uncertainty. Quantification of uncertainty is implemented in the R-package GiANT. We also included widely used GSA methods, embedded in a generic framework that can readily be extended by custom methods. The package provides an easy to use front end and allows for fast parallelization. Availability and implementation: The package GiANT is available on CRAN. Contacts: hans.kestler@leibniz-fli.de or hans.kestler@uni-ulm.de

Background. Acute myeloid leukemia (AML) with a complex karyotype (CK-AML) is an AML subtype with a still dismal outcome despite recent therapeutic advances. The prognosis is even worse when the underlying structural variants (SVs) lead to an extremely complex pattern of rearrangements, called chromothripsis, with a median overall survival of only 120 days. Except for the presence of inactivating TP53 aberrations in about 70% of all AML-CK cases, the pathogenesis is poorly understood. To gain novel insights into the molecular mechanisms underlying CK-AML reliable high precision SV delineation is needed, which so far has been a major limitation in cancer research. Aim. We developed a SV detection pipeline by integrating Oxford Nanopore Technology (ONT) based whole genome sequencing (WGS) and Hi-C sequencing. This pipeline generated precise characterization of SVs for which the impact on gene expression and the emergence of novel fusion genes was studied by RNA-seq and ONT transcriptome sequencing. Patients and Methods. We applied our WGS and Hi-C SV detection pipeline to a cohort of 11 AML-CK cases. Nanopore DNA Sequencing was performed until a genomic coverage >10x per patient was reached. The samples of 9 patients were also subjected to Nanopore cDNA sequencing for fusion gene analysis and Illumina based RNA-seq for transcript quantification. As controls for Hi-C and Illumina RNA sequencing, CD34+ hematopoietic stem cell enriched samples from five healthy donors were used. Results. Our SV detection pipeline enabled us to fully reconstruct the derivate chromosome structure even of very complex, chromothriptic rearrangements in CK-AML. This enabled us to identify features of chromothripsis, that could previously not be detected using conventual technologies. We found local clustering of breakpoints in three of the patients with up to 31 Inversions and Translocations located in a genomic region of just 2.7 kb. These breakpoints were present in the Hi-C as well as in our Nanopore SV dataset. Our SV pipeline also showed that in these highly clustered regions, the very small rejoined fragments (in many cases less than 1 kb in size) often showed an elevated copy number (CN) state, i.e. small amplifications. We termed this newly discovered phenomenon chromothripsis-in-chromothripsis or (chromothripsis)². The precise knowledge about these breakpoints, which were validated by two different technologies, enabled us to study the pathogenesis of CK-AML at a so far unprecedented resolution. Fusion transcripts could be very precisely mapped and the impact of the breakpoints and CN changes on gene expression levels could be validated, thereby indicating functional relevance of the respective aberrations. Conclusions. The combination of Hi-C and long-read sequencing for SV detection proved to be a powerful tool for precise SV detection. Our SV pipeline allowed us to discover a new level of complexity in chromothripsis. Application of this pipeline to leukemias as well as other types of cancer can improve the precision of SV detection, thereby raising new opportunities for functional interpretation of complex genomic aberrations of pathogenic relevance. Disclosures Döhner: Sunesis Pharmaceuticals: Research Funding; Astex Pharmaceuticals: Consultancy; Pfizer: Research Funding; Bristol-Myers Squibb: Research Funding; Arog: Research Funding; Roche: Consultancy; Novartis: Honoraria, Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Daiichi Sankyo: Honoraria; Abbvie: Consultancy; Agios: Consultancy; Janssen: Consultancy, Honoraria; Amgen: Consultancy, Research Funding; Astellas Pharma: Consultancy; Celgene: Consultancy, Honoraria. Schrezenmeier:Alexion Pharmaceuticals Inc.: Honoraria, Research Funding. Bullinger:Amgen: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Menarini: Membership on an entity's Board of Directors or advisory committees.

Background: Acute myeloid leukemias (AML) with rearrangements of core-binding factor (CBF) complex genes (CBF-AML), comprising t(8;21) and inv(16) subgroups, are considered as diseases with favorable outcome. Nevertheless, CBF-AML relapse rates remain high, with ~40% of patients (pts) relapsing after standard intensive chemotherapy. Aim: To dissect the biology of relapse in CBF-AML, we performed whole exome sequencing (WES) in a large cohort of 101 cases at the time of diagnosis and for 47 cases also at the time of relapse. Methods: All pts were treated either with standard chemotherapy or with standard chemotherapy and kinase inhibitor dasatinib within clinical trials of the German-Austrian AML Study Group (AMLSG). Using the Nextera Rapid Capture Exome kit (Illumina) we performed WES of paired diagnostic (dx), remission and relapse samples of 47 pts, namely 21 pts with t(8;21) and 26 pts with inv(16). RNAseq was performed in 18 of these pts using the Ribo Zero RNA-sequencing kit (Illumina). To better define genomic signatures related to CBF-AML relapse, we included WES data previously published by our group (Faber et al. Nat Genet 2016). This set comprised dx samples of 8 t(8;21) and 10 inv(16) pts who relapsed as well as a control group of 20 t(8;21) and 16 inv(16) CBF-AML pts, who did not experience relapse. Results: For the new cohort, WES sequencing of 47 pts was performed with a mean coverage of 127-fold. In t(8;21), we identified a median of 3.5 mutations exclusively present at dx (range: 0-8), 11.6 mutations persistent from dx to relapse (range: 4-19), and 4.0 mutations gained at relapse (range: 2-7). For the inv(16) subgroup a median of 2.0 mutations were dx specific (0-7), 6.0 mutations persisted during tumor evolution (3-26) and 2.5 were gained at relapse (0-9). As previously reported, the spectrum of genes affected by mutations showed little overlap between t(8;21) and inv(16), except for commonly affected 'signaling' genes such as KIT, RAS, FLT3 and epigenetic players such as TET2. In total, in t(8;21) we identified 94 relapse-specific mutations or mutations displaying a strong increase in variant allele frequency (VAF) at relapse, and 63 of such relapse-specific alterations in inv(16) pts. In addition to the previously reported RUNX1 and cohesin complex gene mutations showing an increase in VAF at relapse, we found recurrent novel relapse-specific mutations in LAMC3, which occurred exclusively in the t(8;21) subgroup affecting 9% of pts. In inv(16), recurrent mutations in the tumor suppressor gene WT1 occurred in 12% of pts, either acquired at relapse or already present at dx as a minor subclone. Remarkably, mutations in relapsed t(8;21) pts often affected genes involved in PI3K-AKT and in cell cycle regulation pathways. In the inv(16) relapse group, in addition to dysregulation of the MAPK signaling pathway, we found several non-recurrent mutations in genes involved in ribosomal RNA metabolism, like in PRNAD1. Conclusion: Our WES sequencing results already provide first insights into the molecular composition and mechanisms underlying relapse in CBF-AML which often affect pathways linked to proliferation, such as PI3K-AKT and MAPK signaling. While we are currently validating additional hits, updated results will be provided at the ASH meeting, which will also address combinatorial mutation patterns underlying chemotherapy resistance in t(8;21) and inv(16) positive AML. Disclosures Götze: Celgene: Research Funding. Fiedler:Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria; ARIAD/Incyte: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Other: support for meeting attendance, Patents & Royalties, Research Funding; Daiichi Sankyo: Other: support for meeting attendance; Gilead: Other: support for meeting attendance; Jazz Pharmaceuticals: Honoraria, Other: support for meeting attendance; Abbvie: Membership on an entity's Board of Directors or advisory committees; Morphosys: Consultancy, Honoraria; Celgene: Membership on an entity's Board of Directors or advisory committees. Thol:Celgene: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees. Heuser:PriME Oncology: Honoraria; Abbvie: Consultancy; Stemline Therapeutics: Consultancy; Karyopharm: Research Funding; Roche: Research Funding; Bayer: Consultancy, Research Funding; Amgen: Research Funding; BerGenBio ASA: Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Pfizer: Consultancy, Honoraria, Research Funding; Janssen: Consultancy; Daiichi Sankyo: Consultancy, Research Funding; Astellas: Research Funding. Ganser:Novartis: Consultancy; Celgene: Consultancy. Paschka:Agios Pharmaceuticals: Consultancy, Speakers Bureau; Astex Pharmaceuticals: Consultancy; Astellas Pharma: Consultancy, Speakers Bureau; Celgene: Consultancy, Other: Travel, accommodations or expenses; Jazz Pharmaceuticals: Consultancy, Speakers Bureau; Novartis: Consultancy, Speakers Bureau; Otsuka: Consultancy; Pfizer: Consultancy, Speakers Bureau; Sunesis Pharmaceuticals: Consultancy; AbbVie: Other: Travel, accommodation or expenses, Speakers Bureau; Amgen: Other; Janssen Oncology: Other; BerGenBio ASA: Research Funding. Döhner:GEMoaB: Consultancy, Honoraria; AROG: Research Funding; Astellas: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding; Helsinn: Consultancy, Honoraria; Jazz: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria, Research Funding; Bristol Myers Squibb: Consultancy, Honoraria, Research Funding; Astex: Consultancy, Honoraria; Roche: Consultancy, Honoraria; Pfizer: Research Funding; Oxford Biomedicals: Consultancy, Honoraria; Amgen: Consultancy, Honoraria, Research Funding; Agios: Consultancy, Honoraria, Research Funding; Abbvie: Consultancy, Honoraria; AstraZeneca: Consultancy, Honoraria; Sunesis: Research Funding. Döhner:Novartis: Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Daiichi Sankyo: Honoraria; Abbvie: Consultancy; Sunesis Pharmaceuticals: Research Funding; Pfizer: Research Funding; Bristol-Myers Squibb: Research Funding; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Astex Pharmaceuticals: Consultancy; Astellas Pharma: Consultancy; Amgen: Consultancy, Research Funding; Agios: Consultancy; Roche: Consultancy; Arog: Research Funding. Bullinger:Amgen: Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Membership on an entity's Board of Directors or advisory committees; Gilead: Membership on an entity's Board of Directors or advisory committees; Abbvie: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Hexal: Membership on an entity's Board of Directors or advisory committees; Janssen: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Menarini: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sanofi: Membership on an entity's Board of Directors or advisory committees; Seattle Genetics: Membership on an entity's Board of Directors or advisory committees.

Physiologically, Notch signal transduction plays a pivotal role in differentiation; pathologically, Notch signaling contributes to the development of cancer. Transcriptional activation of Notch target genes involves cleavage of the Notch receptor in response to ligand binding, production of the Notch intracellular domain (NICD), and NICD migration into the nucleus and assembly of a coactivator complex. Posttranslational modifications of the NICD are important for its transcriptional activity and protein turnover. Deregulation of Notch signaling and stabilizing mutations of Notch1 have been linked to leukemia development. We found that the methyltransferase CARM1 (coactivator-associated arginine methyltransferase 1; also known as PRMT4) methylated NICD at five conserved arginine residues within the C-terminal transactivation domain. CARM1 physically and functionally interacted with the NICD-coactivator complex and was found at gene enhancers in a Notch-dependent manner. Although a methylation-defective NICD mutant was biochemically more stable, this mutant was biologically less active as measured with Notch assays in embryos of Xenopus laevis and Danio rerio. Mathematical modeling indicated that full but short and transient Notch signaling required methylation of NICD.

The large acute myeloid leukemia (AML) patient-derived data sets collected within the European HARMONY alliance allows to study the molecular heterogeneity underlying AML in detail. Especially, how cytogenetic and molecular genetic aberrations differentially affect patients. Here, we report first results on the differences in mutational patterns in males and females. We studied a cohort of AML patients characterized by a panel of 70 molecular abnormalities comprising both cytogenetic and genetic observations. We quantified the differences of molecular patterns between sexes in two ways: 1) by comparing the number of gene-gene mutation co-occurrence and mutual mutation exclusivity with a χ 2 test, 2) exploiting the Hierarchical Dirichlet process (HDP) for molecular components discovery. In particular, we added sex as a further layer of the hierarchy allowing the same molecular components to be differently re-weighted based on gender. The HARMONY AML cohort comprised 2796 patients with detailed molecular information from targeted sequencing of 41 genes and detailed cytogenetic information condensed into 29 cytogenetic properties, known, a priori, to be relevant for the disease. Male to female ratio was 52% vs. 48% and median age was 52.0 (18.2 - 91.4) years. The entry data of the analysis were in the form of a binary matrix reporting the presence/absence of a given alteration in a patient. The χ 2 test based on the relative co-occurrence of mutation pairs suggested a significant difference between men and women solely for RUNX1 and NPM1. The number of co-occurrences was higher in male than in females. No significant mutual exclusive mutations were found between the populations. By using a two hierarchic levels HDP clustering we identified 11 overall molecular components shared by all AML patients. Six of these components are characterized by one or more genetic drivers, namely: NPM1, RUNX1, Complex-Karyotype-TP53, FLT3-IDH2, IDH2, CEPBA-biallelic, while the others were driven by cytogenetic abnormalities: t(6;9), t(8;21), inv(3), rearrangement of 11q23, inv(16). These results were in agreement with the current WHO AML classification and with other recent studies, which have attempted to improve stratification/classification of patients based on their molecular aberration patterns. While the molecular components were the same for all patients, major differences were observed in the contribution of NPM1 and RUNX1 components to males' and females' genotypes. On one side, NPM1 component has a double weight in females with respect to males. On the other hand, RUNX1 impacts males much more than females. The other aberrations were equally represented in both sexes. To test the robustness of the differences found between sexes, we compared these results with random splits of the datasets finding no differences in component weights, thereby validating our observations. Big data collections such as the HARMONY Alliance data base ensure data comparability via OMOP common data model harmonization approaches thereby offering the possibility to study large cohort that allow meaningful subgroup analyses such as the one focusing on gender imbalances. Proving the concept of the HARMONY Alliance data hub, our study confirms a female preponderance for NPM1 mutations and an association of RUNX1 mutations with male gender. Impact on patient outcome is currently evaluated and will be presented at the annual meeting. Figure 1 Figure 1. Disclosures Heckman: Celgene/BMS: Research Funding; Orion Pharma: Research Funding; Novartis: Research Funding; Oncopeptides: Consultancy, Research Funding; Kronos Bio, Inc.: Research Funding. Dombret: Abbvie: Honoraria; Amgen: Honoraria, Research Funding; Incyte: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; NOVARTIS: Research Funding; pfizer: Honoraria, Research Funding; servier: Research Funding; BMS-Celgene: Honoraria; Daiichi Sankyo: Honoraria. Montesinos: Tolero Pharmaceutical: Consultancy; Agios: Consultancy; Stemline/Menarini: Consultancy; Teva: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Karyopharm: Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Incyte: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Forma Therapeutics: Consultancy; Glycomimetics: Consultancy; AbbVie: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Astellas Pharma, Inc.: Consultancy, Honoraria, Other: Advisory board, Research Funding, Speakers Bureau. Sierra: Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Novartis: Honoraria, Research Funding, Speakers Bureau; Jazz Pharmaceuticals: Research Funding; Janssen: Other: Educational grant; Roche: Other: Educational grant; Pfizer: Honoraria; BMS Celgene: Honoraria, Research Funding; Alexion: Other: Educational grant; Amgen: Other: Educational grant; Abbvie: Honoraria, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Mayer: Principia: Research Funding. Voso: Novartis: Speakers Bureau; Celgene: Consultancy, Research Funding, Speakers Bureau. Sanz: Roche: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Takeda: Consultancy, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Speakers Bureau; Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Boehringer Ingelheim: Consultancy, Membership on an entity's Board of Directors or advisory committees; Janssen: Consultancy, Membership on an entity's Board of Directors or advisory committees; Gilead Sciences: Other: Travel, accommodations, and expenses; Helsinn Healthcare: Consultancy, Membership on an entity's Board of Directors or advisory committees; Abbvie: Consultancy, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Other: Travel, accommodations, and expenses, Research Funding. Calado: Novartis: Current Employment. Döhner: Agios and Astex: Research Funding; Daiichi Sankyo: Honoraria, Other: Advisory Board; Jazz Roche: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Janssen: Honoraria, Other: Advisory Board; Astellas: Research Funding; Celgene/BMS: Consultancy, Honoraria, Research Funding; Novartis: Consultancy, Honoraria, Research Funding. Gaidzik: Pfizer: Speakers Bureau; Janssen: Speakers Bureau; Abbvie: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau. Heuser: BergenBio: Research Funding; Jazz Pharmaceuticals: Honoraria, Research Funding; BMS/Celgene: Research Funding; Bayer AG: Honoraria, Research Funding; Astellas: Research Funding; Daichi Sankyo: Honoraria, Research Funding; Karyopharm: Research Funding; Novartis: Honoraria, Research Funding; Pfizer: Honoraria, Research Funding; Roche: Research Funding; Tolremo: Honoraria; AbbVie: Honoraria; Janssen: Honoraria. Haferlach: MLL Munich Leukemia Laboratory: Other: Part ownership. Sobas: Celgene: Consultancy, Honoraria; Novartis: Consultancy, Honoraria. Turki: CSL Behring: Consultancy; Jazz Pharma: Consultancy, Speakers Bureau; MSD: Consultancy, Speakers Bureau. Schulze-Rath: Bayer: Current Employment. Hernández Rivas: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene/BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Membership on an entity's Board of Directors or advisory committees. Döhner: Abbvie: Honoraria, Research Funding; Agios: Honoraria, Research Funding; Amgen: Honoraria, Research Funding; Astellas: Honoraria, Research Funding; Astex Pharmaceuticals: Honoraria; AstraZeneca: Honoraria; Berlin-Chemie: Honoraria; Bristol Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; GEMoaB: Honoraria; Gilead: Honoraria; Helsinn: Honoraria; Janssen: Honoraria; Jazz Pharmaceuticals: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Oxford Biomedica: Honoraria; Pfizer: Research Funding; Roche: Honoraria. Ossenkoppele: Abbvie, AGIOS, BMS/Celgene Astellas,AMGEN, Gilead,Servier,JAZZ,Servier Novartis: Consultancy, Honoraria; Servier: Consultancy, Honoraria; Agios: Consultancy, Honoraria; Astellas: Consultancy, Honoraria; BMS/Celgene: Consultancy, Honoraria; Jazz: Consultancy, Honoraria; Gilead: Consultancy, Honoraria. Bullinger: Menarini: Consultancy; Amgen: Honoraria; Hexal: Consultancy; Novartis: Consultancy, Honoraria; Bristol-Myers Squibb: Consultancy, Honoraria; Pfizer: Consultancy, Honoraria; Jazz Pharmaceuticals: Consultancy, Honoraria, Research Funding; Janssen: Consultancy, Honoraria; Celgene: Consultancy, Honoraria; Daiichi Sankyo: Consultancy, Honoraria; Astellas: Honoraria; Abbvie: Consultancy, Honoraria; Gilead: Consultancy; Sanofi: Honoraria; Seattle Genetics: Honoraria; Bayer: Research Funding.