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The outcome of AML patients (pts) ≥ 70 years is poor. Defining the best treatment option remains controversial especially when choosing between intensive chemotherapy (IC) and hypomethylating agents (HMAs). We set up a multicentric European database collecting data of AML pts ≥ 70 y. The primary objective was to compare overall survival in pts selected for IC or HMAs. Individual pt data were collected from 3 European AML registries (DATAML, SAL and PETHEMA). All pts ≥70 y newly diagnosed between 01/01/2007 and 06/30/2018 were included. Variables were age, sex, diagnosis date, AML status, WBC, BM blasts %, cytogenetic risk, NPM1, FLT3-ITD mutations, first-line therapy, response, allo-SCT in first complete remission (CR), date of relapse and/or death. First-line treatments included IC, a semi-intensive regimen (fludarabine, cytarabine, filgrastim), HMAs, low-dose cytarabine (LDAC) or supportive care (SC). 3 700 AML pts ≥ 70y were identified. Pts treated with semi-intensive chemotherapy (n=464), LDAC (n=127) or SC (n=837) were not included in this analysis. Thus, the study population included 1 199 IC pts and 1 073 HMA pts. The median follow-up was 49.5 months. In the HMA group, pts were older, had lower WBC count and BM blast %, and they more frequently had ECOG > 1, secondary AML (sAML) and adverse-risk cytogenetics (CG) compared to the IC group. NPM1 and FLT3-ITD mutations were more frequent in the IC group. IC regimens were daunorubicin-AraC (n=432, 36.0%), idarubicin-AraC (n=381, 31.8%) or ida-AraC-CCNU (n=214, 17.8%). AlloSCT was performed in 70 IC pts (5.8%) and only in 7 HMA pts (0.7%) (P CR/CRi was achieved in 673 (56.1%) and 211 (19.7%) pts in the IC and HMA groups (P 1, adverse-risk CG and WBC >30 giga/L were significantly associated with a lower response rate whereas NPM1 mutation was significantly associated with a higher response rate. HMA treatment was associated with a lower response rate than IC (OR, 0.25; 95%CI : 0.20-0.31 ; P Day-60 death occurred in 247 (20.6%) and 194 (18.1%) pts in the IC and HMA groups (P=0.129). MV analysis showed that age ≥ 75 years, ECOG > 1, adverse-risk CG and WBC > 30 giga/L were significantly associated with a higher d60 death rate. HMA treatment was associated with a lower d60 death rate than IC (OR, 0.69; 95%CI : 0.54-0.88 ; P=0.003). The median OS was 10.9 (95%CI: 9.7-11.6) and 9.2 months (95%CI: 8.3-10.2) in the IC and HMA groups. OS at 1, 3 and 5 y was 46.0 (95%CI: 43.0-48.9) vs. 40.6% (95%CI: 37.6-43.7), 20.8 (95%CI: 18.3-23.4) vs. 8.3% (95%CI: 6.5-10.4) and 12.4 (95%CI: 10.2-14.9) vs 2.8% (95%CI: 1.7-4.4) in the IC and HMA groups. In MV analysis, ECOG > 1, adverse-risk CG, WBC > 30 giga/liter and sAML were significantly associated with a poorer OS. The treatment effect on OS was time-dependent (Fig 1A). To account for the non-proportionality of risks, we used a Royston and Parmar model, which took into account the interactions between time and treatment effect and allowed graphical representation of the adjusted risk of death at all times during follow-up. This model showed that HMA pts had a significantly lower risk of death before 1.5 months of follow-up ; there was no significant difference between both groups between 1.5 and 4.0 months, and OS was significantly better with IC from 4.0 months of follow-up (Fig 1B). There was no significant interaction between treatment (HMAs vs. IC) and all confounding factors (in particular age, performance status or CG risk). We also used the propensity score method. A MV logistic regression model was generated to estimate for each pt a propensity score to receive HMAs or IC. The performance of the model was estimated with the c 2-Hosmer-Lemeshow statistic (P-value= 0.169) and the C-statistic (0.82, 95%CI: 0.81-0.84). The mean propensity score was 0.320 (±0.232) in IC (N=1199) and 0.642 (±0.234) in HMA (N=1073). Based on propensity score, 532 subjects with IC were matched with 532 subjects with HMAs. The mean propensity score was the same in IC and HMA (0.491 ± 0.219) in the matched sample. The results of HMAs vs. IC comparisons on response, early mortality and overall survival (Fig 1C-D) in this subgroup of propensity score-matched pts were similar to those of the MV analysis. With a fairly long median follow-up and a large number of pts, this study shows that IC remains the treatment strategy that offers better chances for prolonged survival compared with HMAs even in AML pts ≥ 70y. Figure 1 Figure 1. Disclosures Recher: Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Roche: 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; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Incyte: Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MaatPharma: Research Funding. Bertoli: Astellas: Consultancy; BMS Celgene: Consultancy; AbbVie: Consultancy; Jazz Pharmaceuticals: Consultancy. Dumas: Daiichi-Sankyo: Consultancy; Astellas: Consultancy; BMS Celgene: Consultancy. Tavitian: Novartis: Consultancy. Platzbecker: AbbVie: Honoraria; Geron: Honoraria; Celgene/BMS: Honoraria; Takeda: Honoraria; Novartis: Honoraria; Janssen: Honoraria. Müller-Tidow: Janssen: Consultancy, Research Funding; Bioline: Research Funding; Pfizer: Research Funding. Baldus: Novartis: Honoraria; Amgen: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria. de la Fuente: Incyte: Consultancy, Speakers Bureau; Abbie: Consultancy, Speakers Bureau; Novartis: Research Funding; BMS: Consultancy, Speakers Bureau. Delabesse: Novartis: Consultancy; Astellas: Consultancy. Pigneux: Roche: Consultancy, Research Funding; BMS Celgene: Consultancy, Research Funding; Sunesis: Consultancy, Research Funding; Amgen: Consultancy; Novartis: Consultancy, Research Funding. Montesinos: Stemline/Menarini: Consultancy; Sanofi: Membership on an entity's Board of Directors or advisory committees, Speakers Bureau; Teva: 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; Novartis: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Pfizer: Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Daiichi Sankyo: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; 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; Glycomimetics: Consultancy; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; Tolero Pharmaceutical: Consultancy; Forma Therapeutics: Consultancy; Agios: 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.

Introduction: Acute Myeloid Leukemia (AML) is a heterogeneous disorder characterized by a wide range of cytogenetic and molecular aberrations, that affect prognosis and guide treatment decisions. However there is a still large group of patients (pts) considered at intermediate risk whose outcome needs to be better defined. Next-generation sequencing (NGS) can simultaneously detect various mutations, leading to better define its prognostic profile. The role of some mutations, including isocitrate dehydrogenase (IDH) mutations (IDHm), is still controversial. Aim: We evaluated by NGS monitoring at different time points the prognostic role of IDH1/2m in AML pts with normal karyotype, both in the subgroup with mutations of NPM1 (NPM1m) or FLT3 (FLT3m) and in the subgroup without detectable mutations (wt-AML). Methods: Using Sophia Myeloid Solution kit (SOPHiA Genetics), we performed targeted NGS, covering 30 gene regions, in 104 bone marrow samples collected at diagnosis (53), after first consolidation (30) and at relapse (21), in 53 pts (M/F: 24/29; median age: 56 y, range 22-74), treated according to NILG-AML00 protocol (NCT00400673). Standard PCR to detect NPM1m and FLT3m was performed and we identified 20 NPM1m, 3 NPM1+FLT3-ITDm, 4 FLT3-ITDm and 26 wt-AML. Results: At diagnosis, among 219 pathogenic mutations detected, IDHm represented 10.5% of them (median VAF: 39.1%; range 6.2-49.6%). IDHm was observed in 23/53 pts (43.4%) (IDH1m in 11 and IDH2m in 12). In these pts , more frequently commutated genes were DNMT3A (28%), NPM1 (13%), FLT3-ITD/TKD (14%), ASXL1 (6%), SRSF2 and NRAS (9% each). Complete remission (CR) was achieved in 49/53 (92.5%) pts without difference in response rate according to IDH status (86% in IDHm vs 94% in IDH wild-type, wt). Relapse occurred in 28/49 (57%) pts after a median of 11 months (mo), range 2-61. The frequency of relapse was not significantly different across all types of mutations identified, except for IDH2m which was associated with a higher risk of relapse (10/11 in IDH2m vs 18/38 in IDH2wt; p: 0.014), without differences between R172K and R140Q. On the contrary, IDH1m, present in 18% of relapsed pts, did not impact on relapse (5/10 vs 23/39, p: 0.7). Particularly, in the wt-AML group, the IDH2m was prevalent in pts developing relapse (6/11, 54.5%) and all pts with IDH2m relapsed, with median of 13 mo, range 6-24 (6/6 in IDH2m vs 5/17 in IDH2wt, p:0.0046). Among the co-occurrence mutations, the IDH2/DNMT3A was associated with higher relapse risk (9/9 vs 19/40; p: 0.0063). DNMT3A associated with other mutations did not impact on relapse risk. At a median follow-up of 23 mo, median relapse free survival (RFS) and overall survival (OS) of whole population were 24 and 53 mo, respectively. The IDH2m impacted on OS: 23.5 mo in IDH2m vs 72 in IDH2wt pts (p:0.0093) (Fig 1a), but not in RFS (13 vs 29 mo in IDH2m and IDH2wt, respectively (p:0.1). Considering the subgroups of wt-AML, the RFS (Fig. 1b) and OS were 13 and 23.5 mo in IDH2m vs undefined in IDH2-wt (p:0.0014 and p:0.1), respectively. In pts with NPM1 or FLT3m, RFS and OS were 9 and 53 mo in IDH2m vs 29 and 73 mo in IDH2-wt (p:0.2 and p:0.15), respectively. We did not find the other genomic pattern predicting relapse in this group. After consolidation, NGS monitoring was performed in 30 pts in CR. Of the 13 IDH AML pts evaluated, no mutations was observed in 4 (28.5%); the persistence of IDHm was not associated with a significantly higher relapse (p:0.5). Among other mutations present at diagnosis, NGS clearance after consolidation occurred in pts with NRAS, KRAS, PTPN11 and FLT3-ITD/TKD. Conversely, it was limited for the following mutations: TET2 (8/11), DNMT3A (7/13), SRSF2 (6/6), IDH2 (4/5), ASXL1 (2/2), IDH1 (2/4) and NPM1 (1/12). Overall, the persistence of any type of gene mutations after consolidation was predictive of relapse (2/9 vs 6/7, p:0.04), only in wt-AML subgroup. At relapse, of the 11 IDHm pts analyzed, 7/7 IDH2m and 3/4 IDH1m showed the reappearance of mutations. Conclusion: In this retrospective monocentric study, the presence at diagnosis of IDH2m correlated with relapse risk and with survival, suggesting that additional treatment with targeted agents and or consolidation with allogeneic transplant should be considered. In addition, in AML without NPM1m or FLT3m, the persistence of genes mutation detected by NGS monitoring after consolidation had a significant prognostic value to predict subsequent relapse. Figure 1 Figure 1. Disclosures Borlenghi: Amgen, Janssen: Consultancy. Rossi: Janssen: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Jazz: Membership on an entity's Board of Directors or advisory committees; Astellas: Membership on an entity's Board of Directors or advisory committees; Daiichi Sankyo: Consultancy, Honoraria; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Alexion: Membership on an entity's Board of Directors or advisory committees; Pfizer: Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria; Abbvie: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees. Tucci: Gentili: Membership on an entity's Board of Directors or advisory committees; janssen: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees.

Hyperleukocytic AML (HL-AML) is characterised by a high risk of early death and poor prognosis. We previously reported the impact of adding dexamethasone (DEX) to intensive chemotherapy in this situation (Bertoli et al, Haematologica 2018). The aim of this study was to give a comprehensive description of HL-AML at the molecular level and to investigate interactions between molecular lesions and DEX treatment. In the earlier study which included 160 patients (pts) (18 - 75 years old) with WBC > 100 x 10 9/L or > 50 x 10 9/L with leukostasis symptoms, multivariate analyses had shown that DEX treatment was significantly associated with better DFS, EFS and OS (Bertoli S, Haematologica 2018). In this pre-midostaurin registration patient cohort (2004-2015), no pt received a FLT3 inhibitor. Diagnostic samples for NGS analyses were available for 154 pts (96.3% of the initial cohort), 59 pts who received DEX with 3+7 induction chemotherapy and 95 pts who did not. The presence of FLT3-ITD was tested as described (Larochelle O, Oncotarget 2011). CEBPA screening was performed by Sanger sequencing (Pabst T, Nat Genet 2001). Extended DNA resequencing was performed using an Illumina NextSeq500 and Sureselect target enrichment system (Agilent, Santa Clara, CA), targeted on the complete coding regions of 79 genes commonly mutated in myeloid malignancies. The cytogenetic risk was favorable, intermediate or adverse in 15 (9.7%), 121 (78.6%) and 18 (11.7%) pts. A total of 616 mutations were identified with an average of 4 mutations/pt (0 to 10 mutations/pt). Only one pt with inv(16) had no mutation detected. The most frequently mutated genes were FLT3 (62%), NPM1 (53%), DNMT3A (34%), TET2 (23%), NRAS (21%), IDH2 (12%), WT1 (11%), PTPN11 (10%), RUNX1 (10%), KRAS (9%) and IDH1 (9%). Of the 71 pts (46%) with FLT3-ITD mutations, 32 (45.1%) had an allelic ratio > 0.5. Mutations in the RAS pathway were detected in 67 pts (44%), including NRAS (n=32, 21%), PTPN11 (n=15, 10%), KRAS (n=14, 9%) and NF1 (n=6, 4%). Overall, a large majority of pts had mutations in signaling genes (n=131, 85.1%). Drug-actionable mutations such as FLT3 (n=96), IDH2 (n=17), IDH1 (n=14), KIT (n=11), TP53 (n=4) or JAK2 (n=1) were detected in 113 patients (73.4%). In patients with FLT3 mutations (n=96), 12 had co-mutations in IDH1 and 12 pts had co-mutations in IDH2. The prognostic impact of the AML genomic classification (Papaemmanuil E, NEJM 2018), NPM1/FLT3-ITD/DNMT3A status, functional gene categories (Bullinger L, JCO 2017) ELN 2017 classification and individual genes was assessed. AML with inv(16)/CBFB-MYH11, CEBPA mutations, NPM1 mutations and myeloid transcription factor gene fusions or mutations were significantly and independently associated with better OS whereas the chromatin-modifying gene subset, NPM1/FLT3-ITD/DNMT3A triple mutations, ELN 2017-adverse risk and DNMT3A mutations were associated with poorer OS. NPM1/FLT3-ITD/DNMT3A triple mutations were observed in 25 pts (16%), 23 of whom died. Compared to this triple mutated subset, lower HRs were found in double mutant NPM1mut/FLT3-ITD (HR, 0.43; 95%CI: 0.19-0.97; P=0.041) or NPM1mut/DNMT3Amut (HR, 0.47; 95% CI: 0.21-1.07; P=0.074). The prognostic impact of each individual gene was assessed using the LASSO statistical method. CBFB-MYH11 (HR, 0.10; 95% CI: 0.02-0.43; P=0.002), CEBPA (HR, 0.22; 95% CI: 0.09-0.53; P=0.001), NPM1 (HR, 0.33; 95% CI: 0.19-0.58; P Median DFS (13.6 months vs 66.3, P=0.002), EFS (11.3 vs 39.4, P=0.002) and OS (18.3 vs not reached, P=0.006) were significantly better in pts who received DEX. In multivariate analyses, no significant interaction between DEX and classifications or gene mutations was found, indicating that the effect of DEX did not differ significantly between the various genetic subsets. This may be due to insufficient numbers or DEX may have broader effects on biological phenomena such as inflammation. Since more than 80% of pts have mutations in signaling genes, inhibition of signaling pathways could improve prognosis of HL-AML. The impact of midostaurin will be interesting to analyse in this setting. Inhibition of the RAS pathway could also be a valuable avenue. Figure 1 Figure 1. Disclosures Bertoli: Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees; BMS: Honoraria, Membership on an entity's Board of Directors or advisory committees; Daiichi-Sankyo: Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Honoraria, Membership on an entity's Board of Directors or advisory committees; Sanofi: Honoraria, Membership on an entity's Board of Directors or advisory committees. Tavitian: Novartis: Consultancy. Vergez: Pierre Fabre Laboratory: Research Funding; Roche: Research Funding. Huguet: Novartis: Other: Advisor; Jazz Pharmaceuticals: Other: Advisor; Celgene: Other: Advisor; BMS: Other: Advisor; Amgen: Other: Advisor; Pfizer: Other: Advisor. Delabesse: Novartis: Consultancy; Astellas: Consultancy. Recher: Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; Janssen: Honoraria; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; MaatPharma: Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, 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; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. OffLabel Disclosure: dexamethasone in hyperleukocytic AML.

DNA replicative stress is associated with malignant transformation. Mini-chromosome maintenance 2 (hereafter Mcm2) is a component of the DNA helicase complex that plays a pivotal role in DNA replication. The Mcm2-7 complex is loaded onto chromatin during the G1-phase of the cell cycle and is required for initiation of DNA replication in the subsequent S-phase. Mice with a Cre cassette inserted into the 3'UTR of the Mcm2 gene (designated Mcm2 Cre) were generated as a tool to assess Mcm2 expression. Unexpectedly, mice with two copies of this allele (Mcm2 Cre/Cre) had decreased expression of Mcm2 protein (~20-30% of the wild type (WT) expression level), likely due to decreased RNA stability caused by insertion of the Cre cassette. Surprisingly, all Mcm2 Cre/Cre mice developed a lethal pre-T lymphoblastic leukemia/lymphoma (pre-T LBL) with a median survival of under 3 months. These pre-T LBL were characterized by 10-20 interstitial deletions of approximately 50-1000 kb, often involving genes known to be mutated or deleted in human pre-T LBL, such as Notch1, Pten, Tcf3, and Cdkn2a. Thus, Mcm2 Cre/Cre mice display a novel mutator/deletor phenotype that results in malignant transformation. Although the Mcm2 hypomorph is a germline defect, the malignancies we identified in Mcm2 Cre/Cre mice were restricted to thymocytes. We hypothesized that Mcm2 Cre/Cre mice were susceptible to non-thymocyte malignancies, but due to the early onset of pre-T LBL (within 4 months of age), these putative non-thymocyte malignancies did not have an opportunity to develop. We transplanted Mcm2 Cre/Cre Lin-Sca-1+Kit+ (LSK) hematopoietic stem/progenitor cells (HSPCs) isolated from 5-week-old Mcm2 Cre/Cre bone marrow into WT recipients, which led to marked anemia and thrombocytopenia without evidence of leukemic transformation at 5 months post-transplant. Consistent with this finding, bone marrow from 5-week-old Mcm2 Cre/Cre mice also showed decreased LSK and Lin-Sca-1-Kit+ (LK) cells compared to WT mice, suggesting that the bone marrow failure was uncovered by the more prolonged survival of Mcm2 Cre/Cre LSK recipients vs. non-transplanted Mcm2 Cre/Cre mice (5 mos. vs. As an alternate approach to preventing pre-T LBL, we crossed the Mcm2 Cre allele onto a nude (nu/nu) background, as nude mice lack thymic epithelial cells, preventing T cell development. Mcm2 Cre/Cre nu/nu mice had markedly prolonged survival compared to Mcm2 Cre/Cre (median 296.5 vs. 80.5 days, respectively; P < 0.0001). Most of the Mcm2 Cre/Cre nu/nu mice succumbed to B-cell precursor acute lymphoblastic leukemia (BCP-ALL) within 10 months of life. To determine whether Mcm2 Cre/Cre nu/nu would develop acute myeloid leukemia (AML) if placed on myeloid leukemia sensitized background, we crossed Mcm2 Cre/Cre nu/nu mice with mice expressing a NUP98-PHF23 (NP23) transgene, as the NP23 fusion gene predisposes mice to develop AML. All Mcm2 Cre/Cre nu/nu NP23 mice died within 5 months of age, primarily due to BCP-ALL. Sparse whole-genome sequencing (WGS) was used to detect copy number aberration (CNA), and we identified recurrent deletions of 100-1000 kb that involved genes known or suspected to be involved in BCP-ALL, including Pax5, Ikzf3, Il7r, and Bcor. Whole-exome sequencing identified recurrent mutations, Jak1/Jak3, Ptpn11, and Kras. In an effort to identify 100-1000 kb interstitial deletions in non-hematopoietic tissue, we used sparse WGS to identify CNA in single-cell cloned mouse embryo fibroblasts (MEF) from Mcm2 Cre/Cre, Mcm2 Cre/Wt, and Mcm2 Wt/Wt mice. Very few CNAs were identified in any of the MEFs. We conclude that this unique deletor phenotype found in Mcm2 Cre/Cre mice is a powerful tool for the identification of tumor suppressor genes in lymphoid leukemia, and that B- and T- lymphocytes are uniquely susceptible to this deletor phenotype. Disclosures No relevant conflicts of interest to declare.

Introduction In the acute myeloid leukemia (AML) setting, artificial intelligence has mainly been used to facilitate diagnosis or to identify biological subcategories. In this work, we trained and compared machine learning and deep learning predictive models of outcome on the data of 3687 consecutive adult AML patients included in the DATAML registry between 2000 and 2019. We also trained a model to predict the best treatment for newly diagnosed AML over 70 years. Methods Feature engineering and selection were done to keep the most relevant variables among clinical and biological characteristics at diagnosis. We worked with 54 features per patient, as well as information about the treatment received (intensive chemotherapy (IC) or azacitidine (AZA)), response and survival. We compared the performance of a gradient boosting algorithm (XGBoost) and three neural networks architectures: a multilayer perceptron (MLP), a neural oblivious decision ensemble model (NODE) and a recurrent relational network (RRN). We calibrated XGBoost with a grid search algorithm, and used 5-fold cross-validation on the dataset to evaluate all the models. The Shapley Additive Explanations method (SHAP) was used to showcase the importance and influence of variables on the predictions. The Boruta algorithm was then used to extract the most important features for prediction. Results In our cohort, 3030 patients (82.2%) received IC and 657 (17.8%) AZA as first line treatment. Median overall survival (OS) was 18 and 9 months, respectively. We first designed models for OS prediction. In the IC cohort, we achieved an accuracy of 68.5% on predicting OS at the 18-month mark, an improvement of 17.5% over a naïve predictor. The Boruta algorithm selected 13 variables as the most important, with decreasing order of importance: age, cytogenetic risk, WBC, LDH, platelets count, albumin, MPO, mean corpuscular volume, CD117, NPM1 mutation, AML status, multilineage dysmyelopoiesis, ASXL1 mutation (Figure 1). When training with only these 13 variables, we achieved an accuracy of 67.8%. In the AZA cohort, we achieved an accuracy of 62.1% on predicting OS at the 9-month mark, an improvement of 11.1% over a naïve predictor. Here the Boruta algorithm selected only 7 variables: blood blasts, serum ferritin, CD56, LDH, hemoglobin, CD13 and the presence of a disseminated intravascular coagulation. When training with only these 7 variables, we achieved a 61.9% accuracy. We then designed models to predict the best treatment between IC and AZA for the 1032 patients older than 70 years. We achieved a 88.5% accuracy, which is 37.5% more than a naïve predictor given the distribution of the cohort: 51% having received IC and 49% having received AZA. For this model, 12 features out of 54 were selected by the Boruta algorithm as the most important: age, TP53 mutation, bone marrow blasts, AML status, disseminated intravascular coagulation, blood blasts, cytogenetic risk, IDH2 mutation, IDH1 mutation, presence of an infection at diagnosis, ASXL1 mutation and presence of leukostasis. Conclusion We show that predictive models can be trained on our database to predict with characteristics at diagnosis the treatment that would be chosen by an expert hematologist between IC and AZA in newly diagnosed AML, give an indication of OS with each treatment, and outperform classical statistical analysis or naïve predictors. For the task of predicting OS, the improvement over naïve predictors is maximal at the median time of OS. We show with the Boruta algorithm that a small number of variables can recapitulate the accuracy of neural networks, which renders this type of model of high interest for routine practice, especially with the advent of targeted therapies. Figure 1 Figure 1. Disclosures Vergez: Pierre Fabre Laboratory: Research Funding; Roche: Research Funding. Dumas: BMS Celgene: Consultancy; Astellas: Consultancy; Daiichi-Sankyo: Consultancy. Tavitian: Novartis: Consultancy. Delabesse: Astellas: Consultancy; Novartis: Consultancy. Pigneux: Amgen: Consultancy; Sunesis: Consultancy, Research Funding; BMS Celgene: Consultancy, Research Funding; Roche: Consultancy, Research Funding; Novartis: Consultancy, Research Funding. Recher: Pfizer: Honoraria, Membership on an entity's Board of Directors or advisory committees; Novartis: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenics: Honoraria, Membership on an entity's Board of Directors or advisory committees; MaatPharma: Research Funding; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Janssen: Honoraria; Incyte: Honoraria; Daiichi Sankyo: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; BMS/Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Roche: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; Agios: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; AbbVie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding. Bertoli: Astellas: Consultancy; BMS Celgene: Consultancy; Abbvie: Consultancy; Jazz Pharmaceuticals: Consultancy.

Introduction Clonal selection is one of the mechanisms leading to therapy-related myeloid neoplasms (TRMN). A preexisting somatic mutation in hematopoietic stem cell (defined as clonal hematopoiesis [CH]) emerges under pressure of chemotherapy or radiotherapy, leading to TRMN development. Most of these mutations belong to the DNA damage response (DDR) pathway as TP53 or PPM1D mutations and are known to confer a dismal prognosis. Recently authorized for the treatment of ovarian cancers (OC), the poly (ADP-ribose) polymerase inhibitors (PARPi) represent a promising targeted therapy. However, by inducing DNA damage and altering DNA repair process, PARP inhibition could represent a challenge for the genetic stability of the healthy tissues. Thus, we assessed the effect of PARP inhibition on the development of CH and TRMN after PARPi treatment for OC (TRMN-PARPi) in combination with chemotherapies. Methods Firstly, we performed a targeted 77 genes mutational analysis using Next Generation Sequencing (NGS) in 13 patients exposed to PARPi without TRMN. Secondly, we retrospectively identified, with the help of the UNIHEM group of Unicancer, 17 patients who experienced TRMN-PARPi. Clinical, biological and survival data were collected and compared to 23 OC patients with TRMN not treated with PARPi (Gustave Roussy institutional database). Lastly, NGS was performed for 3 patients with TRMN-PARPi with sequential sampling. Patient's samples were obtained with informed consent. Results Thirteen OC patients during maintenance treatment with PARPi without TRMN were explored by NGS. Median age at NGS was 64.5 years old (yo) (40.5-75.3). 4/13 (31%) patients harbored BRCA1/2 germline mutation. Time between OC diagnosis and NGS was 4.3 y (1-11.6). The median number of chemotherapy line at PARPi initiation was 2 (1-3). 7 received Olaparib, 5 Niraparib and 1 Rucaparib. The median duration of PARPi treatment before NGS was 4.7 months (1.1-25.1). 12/13 patients experienced hematological toxicities during the PARPi treatment. CH was found in 10/13 (77%) patients (Figure 1a), including mutations of DDR genes in 8/10 (80%). 6/8 (75%) patients had 2 or more gene mutations. Next we identified 17 cases of TRMN occurring during or after PARPi administration for OC (6/17 [35%] t-AML and 11/17 [65%] t-MDS). 12/17 (71%) patients had BRCA germline mutations (7 BRCA1 and 5 BRCA2). All received Olaparib with a median dose of 600mg/d (400-1200). Median duration of Olaparib treatment was 1.7 years (0.2-4.6). TRMN-PARPi were described 1.4 months (0-10.9) after the end of PARPi administration. We compared these patients to a cohort of TRMN post OC not treated by PARPi. Number of therapy lines for OC, time between TRMN and OC diagnosis, median age at TRMN, were, for TRMN-PARPi, 2 (1-8), 5.9 y (0.9-20.8), 64.4 yo (46-74); respectively, compared to 3 (1-8), 4.9 y (1.7-36.9), 59.3 yo (35.7-85.7); (p=ns). TRMN-PARPi cytogenetic was unfavorable for 16/17 (94%) (including 11/17 [65%] complex karyotype) compared to 16/23 (70%) (11/23 [48%] complex karyotype). C Median survival was significantly lower in the TRMN-PARPi group 3.9 months 95%CI [2.0-9.7] and 6.1 months 95%CI [4.1-15.8] respectively, p=0.046, Fig 1b). However, median survival from OC diagnosis was not different between the two groups 6.2 y 95%CI [5.6-NA] for TRMN-PARPi vs 5.6 y 95%CI [5.0-11.6]. NGS was available for 8/17 TRMN-PARPi and revealed mutations in DDR genes in 7/8 patients (6 patients with TP53 mutation, 2 with PPM1D mutation). For 3 patients, we had samples from OC stage, before PARPi administration. We found that mutations from TRMN stage were present at lower frequency, confirming clonal selection by PARPi treatment (Figure 1c). Conclusions Here we described, for the first time, a cohort of TRMN patients previously treated with PARPi for an OC. Intriguingly, most of these TRMN occurred with a short latency at the end of PARPi treatment, with unfavorable cytogenetic and very short OS. Moreover, we found a very high percentage of CH involved in the DDR pathway (62%) in patients under PARPi treatment without TRMN suggesting a potential clonal selection which could lead ultimately to TRMN. PARPi are now indicated in 1rst line high grade OC regardless of BRCA status, which should expand indications. Benefit for OC patients is not questionable; however, caution will be warranted for patients with CH before PARPi treatment, especially implicating DDR mutations. Disclosures Etienne: Incyte: Consultancy, Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Bristol-Myers Squibb: Consultancy, Research Funding, Speakers Bureau; Novartis: Consultancy, Research Funding, Speakers Bureau.

Introduction: While progress has been made in the treatment of childhood leukemia, the outlook for patients >60 years of age with acute lymphoblastic leukemia (ALL) is poor with complete remission rates (CR) of approximately 60% and 3-year survivals (OS) of less than 15%. Intensified treatment in a later CALGB trial showed little improvement with a CR=61% and 5-year OS=6% (Stock, Cancer 2013). Ixazomib is an oral proteasome inhibitor, which has shown single agent activity and promising combination activity in pediatric ALL patients (Messinger, Blood 2012). We sought to assess the safety and tolerability, as well as early efficacy of adding ixazomib to a current MGH-DFCI/HCC multi-agent regimen for older adults with ALL. Methods: Patients aged 51 to 75 years of age with newly diagnosed B-ALL and T-ALL were screened for eligibility. Patients with mature ALL (including Burkitt's) were excluded. Patients with Philadelphia chromosome positive ALL (BCR-ABL1+) were eligible, and dasatinib was added to the chemotherapy on Day 10 for these patients. The chemotherapy treatment schedule from induction through maintenance is outlined in Table 1. A standard 3 + 3 patient cohort dose escalation design was used to determine the maximum tolerated dose (MTD) of ixazomib during induction for these patients, the primary objective of the trial. After consolidation I, patients in complete remission (CR) with a suitable donor were offered a hematopoietic stem cell transplantation (HSCT) as per institutional guidelines. Those not going to HSCT continued therapy as noted in the table. Results: There were 19 patients with B-ALL enrolled, none with T-ALL. Among these patients, 7 harbored BCR-ABL1 rearrangements. The median age was 65 years, 74% were male, and 90% had a performance status 0 or 1. The MTD was 2.3 mg of ixazomib, as 2 patients at 3.0 mg developed DLT's: a grade 3 peripheral neuropathy and a grade 5 acute kidney injury (Table 2). Grade 3 and 4 toxicities encountered at any time consisted mainly of grade 4 neutropenia in 13 patients and grade 4 thrombocytopenia in 12 patients. One patient experienced grade 3 neutropenia and 5 patients experienced grade 3 thrombocytopenia. Two patients with grade 2 neuropathy did not meet the definition of DLT. Among the 19 patients, 15 (79%, [95% confidence interval (CI), 54-94%]) achieved CR (14) or CRi (1), and 5 patients went on to HSCT. The median follow-up time was 2 years (range, 1-5) for 8 patients remaining alive. The 1-year overall survival estimate was 53% [95% CI, 29-72%], while the 2-year overall survival estimate was 47% [95% CI, 24-67%]. Conclusions: A dose of 2.3 mg of ixazomib in combination with induction chemotherapy among older patients with ALL was well-tolerated and associated with a promising rate of complete remission. Disclosures Amrein: Takeda: Research Funding; AstraZeneca: Consultancy, Research Funding; Amgen: Research Funding. Brunner:Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Takeda: Research Funding; AstraZeneca: Research Funding; Forty-Seven Inc: Membership on an entity's Board of Directors or advisory committees; Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Novartis: Research Funding. Hobbs:Novartis: Honoraria; Celgene/BMS: Honoraria; Jazz: Honoraria; Constellation: Honoraria, Research Funding; Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding. Neuberg:Celgene: Research Funding; Pharmacyclics: Research Funding; Madrigak Pharmaceuticals: Current equity holder in publicly-traded company. Fathi:Takeda: Consultancy, Research Funding; Agios: Consultancy, Research Funding; PTC Therapeutics: Consultancy; Amphivena: Consultancy; Astellas: Consultancy; Daiichi Sankyo: Consultancy; Novartis: Consultancy; Newlink Genetics: Consultancy; Pfizer: Consultancy; Blueprint: Consultancy; Trillium: Consultancy; Kura Oncology: Consultancy; Forty Seven: Consultancy; Jazz: Consultancy; Boston Biomedical: Consultancy; BMS/Celgene: Consultancy, Research Funding; Kite: Consultancy; Trovagene: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Abbvie: Consultancy. OffLabel Disclosure: MLN 9708, ixazomib is FDA approved for multiple myeloma. In this trial it is used to treat acute lymphoblastic leukemia.

Introduction: Outcomes for acute myeloid leukemia (AML) among older patients has remained largely unchanged for decades. Long-term survival for patients aged >60 years is poor (median survival 10.5 months). Targeting the proteasome in AML is attractive, since leukemia stem cells have demonstrated sensitivity to proteasome inhibition in preclinical models, perhaps through down regulation of nuclear NF-KB (Guzman, Blood 2001). AML cell lines are susceptible to synergistic cytotoxicity when bortezomib, a proteasome inhibitor, is combined with daunorubicin and cytarabine. We have shown that adding bortezomib to standard treatment in AML results in a high remission rate, although grade 2 sensory neurotoxicity was noted in approximately 12% of treated patients. A newer generation proteasome inhibitor, ixazomib, is less frequently associated with neurotoxicity, and, therefore, was selected for combination with conventional chemotherapy in this phase I trial. The primary objective of this study was to determine the maximum tolerated dose (MTD) of ixazomib in combination with conventional induction and consolidation chemotherapy for AML. Herein are the initial results of this trial. Methods: Adults >60 years of age with newly diagnosed AML were screened for eligibility. Patients with secondary AML were eligible, including those with prior hypomethylating agent therapy for myelodysplastic syndromes (MDS). We excluded those with promyelocytic leukemia. There were 2 phases in this study. In the first phase (A), the induction treatment consisted of the following: cytarabine 100 mg/m2/day by continuous IV infusion, Days 1-7; daunorubicin 60 mg/m2/day IV, Days 1, 2, 3, and ixazomib was provided orally at the cohort dose, Days 2, 5, 9, and 12. Consolidaton or transplant was at the discretion of the treating physician in phase A. In the second phase (B), induction was the same as that with the determined MTD of ixazomib. All patients were to be treated with the following consolidation: cytarabine at 2 g/m2/day, days 1-5 with ixazomib on days 2, 5, 9, and 12 at the cohort dose for consolidation. A standard 3 + 3 patient cohort dose escalation design was used to determine whether the dose of ixazomib could be safely escalated in 3 cohorts (1.5 mg/day, 2.3 mg/day, 3.0 mg/day), initially in induction (phase A) and subsequently in consolidation (phase B). The determined MTD of ixazomib in the first portion (A) of the trial was used during induction in the second portion (B), which sought to determine the MTD for ixazomib during consolidation. Secondary objectives included rate of complete remission, disease-free survival, and overall survival (OS). Results: Thirty-six patients have been enrolled on study, and 28 have completed dose levels A-1 through A-3 and B1 through B-2. Full information on cohort B-3 has not yet been obtained, hence, this report covers the experience with the initial 28 patients, cohorts A-1 through B-2. There were 12 (43%) patients among the 28 with secondary AML, either with prior hematologic malignancy or therapy-related AML. Nineteen patients (68%) were male, and the median age was 68 years (range 61-80 years). There have been no grade 5 toxicities due to study drug. Three patients died early due to leukemia, 2 of which were replaced for assessment of the MTD. Nearly all the grade 3 and 4 toxicities were hematologic (Table). There was 1 DLT (grade 4 platelet count decrease extending beyond Day 42). There has been no grade 3 or 4 neurotoxicity with ixazomib to date. Among the 28 patients in the first 5 cohorts, 22 achieved complete remissions (CR) and 2 achieved CRi, for a composite remission rate (CCR) of 86%. Among the 12 patients with secondary AML 8 achieved CR and 2 achieved CRi, for a CCR of 83%. The median OS for the 28 patients has not been reached (graph). The 18-month OS estimate was 65% [90% CI, 50-85%]. Conclusions: The highest dose level (3 mg) of ixazomib planned for induction in this trial has been reached safely. For consolidation there have been no serious safety issues in the first 2 cohorts with a dose up to 2.3 mg, apart from 1 DLT in the form of delayed platelet count recovery. The recommended phase 2 dose of ixazomib for induction is 3 mg. Accrual to cohort B-3 is ongoing. Notably, to date, no grade 3 or 4 neurotoxicity has been encountered. The remission rate in this older adult population with the addition of ixazomib to standard chemotherapy appears favorable. Figure Disclosures Amrein: Amgen: Research Funding; AstraZeneca: Consultancy, Research Funding; Takeda: Research Funding. Attar:Aprea Therapeutics: Current Employment. Brunner:Jazz Pharmaceuticals: Membership on an entity's Board of Directors or advisory committees; Forty-Seven Inc: Membership on an entity's Board of Directors or advisory committees; AstraZeneca: Research Funding; Takeda: Research Funding; Celgene: Membership on an entity's Board of Directors or advisory committees, Research Funding; Novartis: Research Funding. Hobbs:Constellation: Honoraria, Research Funding; Novartis: Honoraria; Incyte: Research Funding; Merck: Research Funding; Bayer: Research Funding; Jazz: Honoraria; Celgene/BMS: Honoraria. Neuberg:Celgene: Research Funding; Madrigak Pharmaceuticals: Current equity holder in publicly-traded company; Pharmacyclics: Research Funding. Fathi:Blueprint: Consultancy; Boston Biomedical: Consultancy; BMS/Celgene: Consultancy, Research Funding; Novartis: Consultancy; Kura Oncology: Consultancy; Trillium: Consultancy; Amgen: Consultancy; Seattle Genetics: Consultancy, Research Funding; Abbvie: Consultancy; Pfizer: Consultancy; Newlink Genetics: Consultancy; Forty Seven: Consultancy; Trovagene: Consultancy; Kite: Consultancy; Daiichi Sankyo: Consultancy; Astellas: Consultancy; Amphivena: Consultancy; PTC Therapeutics: Consultancy; Agios: Consultancy, Research Funding; Takeda: Consultancy, Research Funding; Jazz: Consultancy. OffLabel Disclosure: Ixazomib is FDA approved for multiple myeloma. We are using it in this trial for acute myeloid leukemia.

NPM1 mutations are frequent in acute myeloid leukemia (AML) and define a distinct entity according to the 2016 WHO classification. NPM1 mutations are generally associated with chemosensitivity and a favorable prognosis. However, outcome may vary according to co-mutational events, and still approximately 40% of patients relapse after achieving complete response. Wild-type NPM1 is mainly located in the nucleolus where it plays a key role in the regulation of ribosome biogenesis, protein synthesis and tumor suppression through TP53 activation. Mutated NPM1 loses its predominant nucleolar location and accumulates in cytoplasm contributing to leukemogenesis (Falini B, Blood 2011). Moreover, this mutational event leads to haploinsufficiency and cytoplasmic retention of wild type NPM1 creating a vulnerability to nucleolar stress. Indeed, complete responses have been observed in NPM1-mutated AML patients with dactinomycin, a nucleolar stress-inducing drug (Falini B, NEJM 2015). Here, we report our experience of off-label dactinomycin in untreated or relapsed/ refractory NPM1-mutated AML. Inclusion criteria for this retrospective study were: age ≥ 18 years-old, AML with NPM1 mutation, relapsed or refractory disease as well as treatment-naive patients unfit for intensive chemotherapy. Patients should also have completed one cycle of dactinomycin 12.5 µg/kg/day for 5 days every 28 days. From September 2015 to February 2019, 26 patients received dactinomycin. Median age was 62.5y, WBC count was > 50 giga/L in 8 patients (31%), 13 patients (50%) had FLT3-ITD mutation whereas 10 (38%) and 11 (42%) patients were classified as favorable or intermediate-I according to the ELN-2010 classification. There were 7 (27%) relapses post-allogeneic transplantation. Median number of dactinomycin cycle was 1 (1-8) and 7 patients (27%) received more than 3 cycles. Sorafenib was added in 6 patients with associated FLT3-ITD mutations whereas 2 others patients received ATRA in combination with dactinomycin. Dactinomycin was administered in different situations: front-line treatment in 4 unfit patients (16%); morphologic (n=16, 62%) or molecular relapses (n=4, 16%) following intensive chemotherapy, refractory disease (n=1, 13%) or post remission therapy in second complete response (CR) following salvage chemotherapy (n=1, 13%). Three out of 17 patients (18%) in morphologic relapse or refractory to chemotherapy reached complete remission after the first cycle of dactinomycin. The duration of response was 4 and 6 months in 2 patients whereas the third patient is still in CR 3 years after dactinomycin. One out of 4 patients in molecular relapses achieved a complete molecular remission with dactinomycin. None of the 4 patients unfit for intensive chemotherapy responded to dactinomycin as front-line therapy. The only patient treated in post-CR2 with dactinomycin achieved a complete molecular remission before allogeneic transplantation. Overall, 5 patients (19%) appeared to benefit from dactinomycin treatment. Grade 3-4 adverse events were thrombocytopenia (n=11, 42%), neutropenia (n=11, 42%), GI toxicity (n=6, 23%), mucositis (n=5, 19%), lung infection (n=5, 19%) and skin rash (n=2, 7.6%). Dactinomycin is an inexpensive and easily available drug that may induce significant responses in AML patients with NPM1 mutations with an acceptable safety profile. Prospective and controlled clinical trials are mandatory to clearly define the role of this agent in AML with NPM1 mutations. Disclosures Tavitian: Novartis: Membership on an entity's Board of Directors or advisory committees. Bertoli:Sanofi: Honoraria. Huguet:Incyte Biosciences: Honoraria; Servier: Honoraria; Amgen: Honoraria; Pfizer: Honoraria; BMS: Honoraria; Jazz Pharmaceuticals: Honoraria; Novartis: Honoraria. Bories:Abbvie: Consultancy. Recher:Novartis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Incyte: Honoraria; Abbvie: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees; Jazz: Consultancy, Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding; Celgene: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Macrogenics: Consultancy, Membership on an entity's Board of Directors or advisory committees; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Amgen: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Sunesis: Consultancy, Membership on an entity's Board of Directors or advisory committees, Research Funding; Astellas: Consultancy, Membership on an entity's Board of Directors or advisory committees. OffLabel Disclosure: NPM1 mutations are frequent in acute myeloid leukemia (AML) and define a distinct entity according to the 2016 WHO classification. Wild-type NPM1 is mainly located in the nucleolus where it plays a key role in the regulation of ribosome biogenesis, protein synthesis and tumor suppression through TP53 activation. Mutated NPM1 loses its predominant nucleolar location and accumulates in cytoplasm contributing to leukemogenesis (Falini B, Blood 2011). Moreover, this mutational event leads to haploinsufficiency and cytoplasmic retention of wild type NPM1 creating a vulnerability to nucleolar stress. Indeed, complete responses have been observed in NPM1-mutated AML patients with dactinomycin, a nucleolar stress-inducing drug (Falini B, NEJM 2015).