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Purpose:The stromal and immune bone marrow (BM) landscape is emerging as a crucial determinant for acute myeloid leukemia (AML). Regulatory T cells (Treg) are enriched in the AML microenvironment, but the underlying mechanisms are poorly elucidated. Here, we addressed the effect of IFNγ released by AML cells in BM Treg induction and its impact on AML prognosis.Experimental Design:BM aspirates from patients with AML were subdivided according to IFNG expression. Gene expression profiles in INFγhigh and IFNγlow samples were compared by microarray and NanoString analysis and used to compute a prognostic index. The IFNγ release effect on the BM microenvironment was investigated in mesenchymal stromal cell (MSC)/AML cell cocultures. In mice, AML cells silenced for ifng expression were injected intrabone.Results:IFNγhigh AML samples showed an upregulation of inflammatory genes, usually correlated with a good prognosis in cancer. In contrast, in patients with AML, high IFNG expression was associated with poor overall survival. Notably, IFNγ release by AML cells positively correlated with a higher BM suppressive Treg frequency. In coculture experiments, IFNγhigh AML cells modified MSC transcriptome by upregulating IFNγ-dependent genes related to Treg induction, including indoleamine 2,3-dioxygenase 1 (IDO1). IDO1 inhibitor abrogated the effect of IFNγ release by AML cells on MSC-derived Treg induction. In vivo, the genetic ablation of IFNγ production by AML cells reduced MSC IDO1 expression and Treg infiltration, hindering AML engraftment.Conclusions:IFNγ release by AML cells induces an immune-regulatory program in MSCs and remodels BM immunologic landscape toward Treg induction, contributing to an immunotolerant microenvironment.See related commentary by Ferrell and Kordasti, p. 2986

Supplementary Data from Release of IFNγ by Acute Myeloid Leukemia Cells Remodels Bone Marrow Immune Microenvironment by Inducing Regulatory T Cells

Purpose: The stromal and immune bone marrow (BM) landscape is emerging as a crucial determinant for acute myeloid leukemia (AML). Regulatory T cells (Treg) are enriched in the AML microenvironment, but the underlying mechanisms are poorly elucidated. Here, we addressed the effect of IFNγ released by AML cells in BM Treg induction and its impact on AML prognosis. Experimental Design: BM aspirates from patients with AML were subdivided according to IFNG expression. Gene expression profiles in INFγhigh and IFNγlow samples were compared by microarray and NanoString analysis and used to compute a prognostic index. The IFNγ release effect on the BM microenvironment was investigated in mesenchymal stromal cell (MSC)/AML cell cocultures. In mice, AML cells silenced for ifng expression were injected intrabone. Results: IFNγhigh AML samples showed an upregulation of inflammatory genes, usually correlated with a good prognosis in cancer. In contrast, in patients with AML, high IFNG expression was associated with poor overall survival. Notably, IFNγ release by AML cells positively correlated with a higher BM suppressive Treg frequency. In coculture experiments, IFNγhigh AML cells modified MSC transcriptome by upregulating IFNγ-dependent genes related to Treg induction, including indoleamine 2,3-dioxygenase 1 (IDO1). IDO1 inhibitor abrogated the effect of IFNγ release by AML cells on MSC-derived Treg induction. In vivo, the genetic ablation of IFNγ production by AML cells reduced MSC IDO1 expression and Treg infiltration, hindering AML engraftment. Conclusions: IFNγ release by AML cells induces an immune-regulatory program in MSCs and remodels BM immunologic landscape toward Treg induction, contributing to an immunotolerant microenvironment. See related commentary by Ferrell and Kordasti, p. 2986

Although targeting of cell metabolism is a promising therapeutic strategy in acute myeloid leukemia (AML), metabolic dependencies are largely unexplored. We aimed to classify AML patients based on their metabolic landscape and map connections between metabolic and genomic profiles. Combined serum and urine metabolomics improved AML characterization compared with individual biofluid analysis. At intracellular level, AML displayed dysregulated amino acid, nucleotide, lipid, and bioenergetic metabolism. The integration of intracellular and biofluid metabolomics provided a map of alterations in the metabolism of polyamine, purine, keton bodies and polyunsaturated fatty acids and tricarboxylic acid cycle. The intracellular metabolome distinguished three AML clusters, correlating with distinct genomic profiles: NPM1-mutated(mut), chromatin/spliceosome-mut and TP53-mut/aneuploid AML that were confirmed by biofluid analysis. Interestingly, integrated genomic-metabolic profiles defined two subgroups of NPM1-mut AML. One was enriched for mutations in cohesin/DNA damage-related genes (NPM1/cohesin-mut AML) and showed increased serum choline + trimethylamine-N-oxide and leucine, higher mutation load, transcriptomic signatures of reduced inflammatory status and better ex-vivo response to EGFR and MET inhibition. The transcriptional differences of enzyme-encoding genes between NPM1/cohesin-mut and NPM1-mut allowed in silico modeling of intracellular metabolic perturbations. This approach predicted alterations in NAD and purine metabolism in NPM1/cohesin-mut AML that suggest potential vulnerabilities, worthy of being therapeutically explored.

Somatic mutations of DNMT3A occur in about 20% of acute myeloid leukemia (AML) patients. They mostly consist in heterozygous missense mutations targeting a hotspot site at R882 codon, which exhibit a dominant negative effect and are associated with high myeloblast count, advanced age, and poor prognosis. Other types of mutations such as truncations, insertions, or single-nucleotide deletion also affect the DNMT3A gene, though with lower frequency. The present study aimed to characterize two DNMT3A gene mutations identified by next-generation sequencing (NGS), through analysis of protein stability and DNA methylation status at CpG islands. The first mutation was a single-nucleotide variant of DNMT3A at exon 20 causing a premature STOP codon (c.2385G > A; p.Trp795∗; NM_022552.4). The DNMT3A mutation load increased from 4.5% to 38.2% during guadecitabine treatment, with a dominant negative effect on CpG methylation and on protein expression. The second mutation was a novel insertion of 35 nucleotides in exon 22 of DNMT3A (NM_022552.4) that introduced a STOP codon too, after the amino acid Glu863 caused by a frameshift insertion (c.2586_2587insTCATGAATGAGAAAGAGGACATCTTATGGTGCACT; p. Thr862_Glu863fsins). The mutation, which was associated with reduced DNMT3A expression and CpG methylation, persisted at relapse with minor changes in the methylation profile and at protein level. Our data highlight the need to better understand the consequences of DNMT3A mutations other than R882 substitutions in the leukemogenic process in order to tailor patient treatments, thus avoiding therapeutic resistance and disease relapse.

Acute Myeloid Leukemia (AML) is a clonal disease developing from a rare population of leukemic stem cells. Alongside the identification of disease-specific alleles harbored by AML clones, the contribution that cell-extrinsic factors have in AML generation and persistence by influencing AML cell genomic landscape and therapy-resistance is gaining increasing interest. In the cross-talk between AML cells and their microenvironment, several membrane receptors sense the external changes by triggering intracellular signals. Among these, the largest group belongs to the family of G protein-couple receptors (GPCRs). Bitter taste receptors (T2Rs) comprise 25 distinct members of the GPCR family. Initially described in the oral cavity, T2Rs are actually widely expressed in different tissues and in various cancer cell types. In the present work, we showed that AML cells expressed fully functional T2R subtypes. Their activation substantially modified the AML cell transcriptomic profile and deregulated relevant cellular processes, resulting in inhibited clonogenic capacity, proliferation and cell motility and induced apoptosis. In addition, T2R stimulation with agonist altered mitochondrial bioenergetic capacity and made AML cells more prone to oxidative and metabolic stress. Given the effect of T2R activation on crucial AML cell function, we tested the therapeutical potential of targeting T2Rs. Interestingly, we observed that T2R stimulation had a synergistic effect with cytarabine, reducing leukemia cell viability and allowing to reach high toxicity using lower doses of chemotherapic agent. Then we analyzed T2Rs expression and function on normal hematopoietic stem cells (HSCs). HSCs expressed several T2R subtypes with some differences compare to AML cells. T2Rs activation didn't affect HSCs viability and motility, conversely to AML cells, but significantly inhibited clonogenic capacity, by reducing the frequency of precursors. Our data may suggest a role for microenvironment “bitter” molecules in regulating normal and leukemic hematopoiesis. Notably, many common drugs, such as antibiotics, chloroquine, haloperidol, procainamide, are bitter tasting and are thus effective ligands for T2Rs. For this reason, they could exhibit an off-target effect in T2R expressing cells, including leukemic and normal hematopoietic cells. Our results may have implications in understanding the off-target actions of diverse drugs and could reveal potential new therapeutic targets Citation Format: Valentina Salvestrini, Valentina Pensato, Marilena Ciciarello, Giorgia Simonetti, Samantha Bruno, Martina Pazzaglia, Elena De Marchi, Dorian Forte, Stefania Orecchioni, Giovanni Martinelli, Francesco Bertolini, Simon Mendez-Ferrer, Elena Adinolfi, Michele Cavo, Antonio Curti. Bitter taste receptors system is expressed and functional in both HSCs and leukemic cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 4946.

Introduction: PPM1D (wild-type p53-inducible protein phosphatase WIP1) is a member of the PP2C family serine/threonine phosphatase involved in negative regulation of cell stress response pathways, leading to suppression of p53 after stress. To restore p53 function through MDM2 inhibition (Nutlin-3a) is a promising approach in AML. Promising results of the combination of MDM2 inhibitors and WIP1 inhibitor (WIP1i), obtained in many preclinical studies of solid tumors, paved the way for their application in AML. We investigated whether the inhibition of WIP1 (GSK2830371) could sensitize AML cell lines and primary cells to Nutlin-3a (Nut-3a) in order to obtain a novel therapeutic strategy for AML patients, based on restoration of p53 activity. Methods: In vitro viability (by WST-1 reagent) and Annexin-V/PI apoptosis assay were performed on a panel of TP53-wt AML cells (MOLM-13, MV-4-11 and OCI-AML3), on TP53-mutated NOMO-1 AML cells and on primary AML samples. Gene expression profile (GEP) and Western Blot (WB) analyses were performed on MV-4-11 and NOMO-1 after 16h. Results: Combined inhibition of increasing dosage of Nut-3a (0.5 to 5 uM) and WIP1i (5 to 20 uM) synergistically reduces TP53-wt AML cells viability, while NOMO-1 resulted to be insensitive to the combination. The combination index analyses showed a synergistically effect of the combination of both compounds on TP53-wt AML cells. Annexin V/PI staining showed that WIP1i sensitizes TP53-wt AML cell lines and primary samples to Nut-3a-induced apoptosis, when compared with single treatment. No effect was seen in NOMO-1. GEP demonstrated that MV-4-11 cells exhibits a major response to drug combination with an upregulation of cell cycle control genes, a downregulation of DNA repair machinery genes, upregulation of MDM2 and of TP53-downstream genes (eg.CDKN1A), confirming the activation of p53 pathway. NOMO-1 cells showed upregulation of resiliency-mechanism and confirmed insensitivity to both treatment. WB analysis confirmed GEP data showing an increased expression of p53 and p21 in wt-TP53 cell line after 16h of combined-treatment. Conclusions: We identified a novel synergistic drug combination between Nut-3a and WIP1i that induces apoptosis in AML cell lines and primary samples. GEP and WB of TP53-wt MV-4-11 and TP53-mutated NOMO-1 cells showed mechanisms underlying drug sensitivity and resistance giving novel insights on potential markers of response and novel drugable targets. In vivo studies are needed to confirm these preclinical data. Supported by: AIRC, FP7-NGS-PTL, Fondazione del Monte, HARMONY. Citation Format: Maria Chiara Fontana, Jacopo Nanni, Giovanni Marconi, Martina Pazzaglia, Matteo Bocconcelli, Antonella Padella, Simona Soverini, Ilaria Iacobucci, Cristina Papayannidis, Anna Ferrari, Maria Teresa Bochicchio, Enrica Imbrogno, Michele Cavo, Andrea Ghelli Luserna di Rora, Giorgia Simonetti, Giovanni Martinelli. Pharmacological inhibition of WIP1 by GSK2830371 sensitizes AML cells to MDM2 inhibitor Nutlin-3a [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2964.

Genomic and functional alterations of enzymatic activity drive cancer metabolic reprogramming along with mutations of tumor suppressors and oncogenes. IDH1/2 lesions represent a paradigmatic example in acute myeloid leukemia (AML). The study aimed to stratify AML patients based on their metabolic landscape and to map potential connections between their metabolic and genomic profile. The genomic landscape of 166 AML patients was obtained by whole exome sequencing. Variants were called by MuTect and Varscan2. Six additional cases were analyzed by targeted sequencing (SOPHiA GENETICS). Metabolites were quantified by mass spectrometry of bone marrow cells (35 CD34+ and 15 CD33+ AML from the above-mentioned cohort) and compared with CD34+ cord blood and CD33+ healthy blood cells (n=21 each, Metabolon) by Welch's t-test. In AML, 17% of somatic variants targeted metabolism-related genes: 38% were enzymes (according to Recon2), including 3% of electron transport chain genes encoded by mitochondrial DNA (COX1-3, ND1-6), 3% were AML-related genes with a known involvement in cell metabolism (e.g. IDH1/2, MYC, KRAS) and 59% were metabolic regulators, defined by gene ontology annotation. Ninety-one% of patients carried at least one mutation in a metabolism-related gene, with 43% of variants rated as damaging. The most represented pathways were lipid, carbohydrate, nucleotide (AK9, H6PD), amino acids (IDO2) and glucose metabolism (PKM, HK3). Principal component analysis of metabolic data showed a distinct profile between AML and healthy cells, with a predictive accuracy of 86% and 95% for CD34+ and CD33+ cells, respectively. Conversely, few differences were observed between CD34+ and CD33+ AML. Unsupervised hierarchical clustering clearly defined 3 AML clusters (C1-3). Moreover, 3 subgroups could be identified in C3 without ambiguous assignments. C1 was enriched for NPM1-mutated (mut) cases (83%, 33%, 27% in C1, C2 and C3, respectively, p=0.03). NPM1-mutated AML were distinguished by a 12-metabolites signature. They showed increased levels of spermidine, cytidine 2′ or 3′-monophosphate (P), thymidine 3′-monoP, uridine-2',3'-cyclic monoP and decrease of inosine 5'-monoP, suggesting altered polyamine, pyrimidine and purine metabolism. Moreover, NPM1-mut AML had reduced levels of intermediates involved in acyl carnitine, lysophospholipid, phosphatidylethanolamine and sphingolipid metabolism. Overall, mutations of metabolism-related genes are common in AML. We defined a metabolic-based classification of AML and identified a new metabolic signature based on 12 metabolites that distinguish NPM1-mut AML from wild-type cases and healthy CD34+/CD33+ cells. Major alterations in the nucleotide and polyamine pathways suggest novel potential therapeutic approaches. Supported by: EHA research fellowship award, AIRC, FP7-NGS-PTL, Fondazione del Monte. Citation Format: Giorgia Simonetti, Antonella Padella, Eugenio Fonzi, Martina Pazzaglia, Margherita Perricone, Maria Chiara Fontana, Samantha Bruno, Maria Teresa Bochicchio, Eugenia Franchini, Jacopo Nanni, Giovanni Marconi, Italo F. do Valle, Rossella De Tommaso, Anna Ferrari, Enrica Imbrogno, Claudio Cerchione, Cristina Papayannidis, Emanuela Ottaviani, Daniel Remondini, Giovanni Martinelli. Metabolic profiling defines a new characterization of acute myeloid leukemia and identifies NPM1-mutated cases as a distinct subgroup [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 5279.

Introduction Monosomy 7 (-7) and interstitial deletions of chromosome 7 (7q-) are among the most recurrent chromosomal aberrations found in myeloid neoplasms. Patients carrying these cytogenetical alterations present a poor overall survival (OS), mainly due to a low sensitivity to standard chemotherapy and a high incidence of relapse. In our study, we aimed to disentangle the biology of patients with -7/7q- and find new candidate therapeutic targets for a disease with such a dismal prognosis, by integrating wide genomic approaches. Methods We collected bone marrow samples from 487 adult patients at diagnosis, treated in 3 institutions: Institute L. & A. Seragnoli (Italy, n = 213), CEMM (Austria, n = 160), University of Michigan (US, n = 114, GSE23452). Three hundred ninety-five samples were analyzed by SNP arrays (Affymetrix™), 51 samples by mass spectrometry (Metabolon™) and 57 samples by GEP (Affymetrix™) approaches. Chi-squared, fisher's exact test and ANOVA were used to test differences in proportion and distributions. False discovery rate, Bonferroni correction, and Welch's correction were calculated whenever appropriate. Results Among the 474 patients with evaluable karyotype, 65 (13.7%) had -7/7q-; 47 (9.9%) had -7, while 18 (3.8%) had 7q-. In our sets, the median age at AML diagnosis was 64 years (21-86) and most of the subjects had a de novo AML (65.1%). WBC count at diagnosis was significantly lower in -7/7q- patients (10.4 vs 35.2 k/mm3 p Within patients tested for FLT3, NPM1 and TP53 mutation at diagnosis, 1/50 among -7/7q- patients vs 59/300 controls harbored FLT3 ITD mutation (350 patients tested, 2% vs 19.7%, p In terms of outcome, -7/7q- AML had a median of overall survival of 10.3 months (95% C.I 5.8-14.8), which accounted for 49.5 months (95% C.I. 40.5-58.4) in other AML cases. GEP data of a cohort of 57 patients (8 with -7/7q- and 49 controls) revealed that 24 genes were under-expressed in -7/7q- AML (with e-4 significance threshold, Figure 1A). Twenty-three out of 24 genes mapped on chromosome 7; one gene, COX17, mapped on chromosome 3 (Figure 1A). COX17 plays a role in the recruitment of copper to mitochondria. By metabolomic analyses, we considered quantitative data of 300 different metabolites in 32 patients (4 with -7/7q- vs 28 controls, 19 patients were excluded because samples at diagnosis were not available). In -7/7q- AML, fatty acids (sphingomyelin, 1-linoleoylglycerol), β-cytrilglutamate and the UDP were overrepresented if compared with other AML cases; on the other hand, galactiol and 1-(1-enyl-palmitoyl)-2-linoleoyl-GPC were underrepresented in -7/7q- patients. Furthermore, -7/7q- AML cells seem to accumulate 3-hydroxy-3-methylglutarate and to have lower levels of 2-Hydroxyglutarate (Figure 1C). With SNP arrays, we considered copy number alterations in 395 patients (52 -7/7q- patients vs 343 controls, Figure 1B). 5q was the most recurrent concurrent deletion, with a minimal common deleted region (MCDR) in q31.3-q33.3. Additionally, 17p (MCDR p11.2 - p13.1), 12p (MCDR p12.3-p13.1), 16q (MCDRs q11.2-q12.1, q21-q22.1 and q24.2-q24.3), 16p (MCDR p11.2) and chromosome 4 (MCDRs q34.1 and q35.2) deletions also co-occurred in -7/7q-, listed per frequencies (Figure 1B). These regions are enriched for genes controlling cell signaling, DNA transcription, post-transcriptional modifications (such as SUMOylation), mRNA splicing and cellular senescence. Conclusions SNP, GEP and metabolomic approaches gave new insights on -7/7q- AML biology, identifying 24 new genes differentially expressed in -7/7q-, and 6 MCDR associated with -7/7q- AML. Deletion of chromosome 16q and 4 were never reported in literature associated to AML. Furthermore, for the first time, we described metabolites associated with -7/7q- AML. These data may represent a useful backbone to search for candidate targets in the setting of one of the most aggressive AML subtypes. Supported by:EHA Non-Clinical Junior Research Fellowship,HARMONY,Fondazione del Monte,FP7-NGS-PTL,AIRC. *MCF and MO equally contributed &CP and GS shared the last authorship Disclosures Haferlach: MLL Munich Leukemia Laboratory: Employment, Equity Ownership. Kralovics:MyeloPro Diagnostics and Research GmbH: Equity Ownership. Soverini:Incyte Biosciences: Consultancy; Bristol Myers Squibb: Consultancy; Novartis: Consultancy. Martinelli:Ariad/Incyte: Consultancy; Celgene: Consultancy, Speakers Bureau; Novartis: Speakers Bureau; Pfizer: Consultancy, Speakers Bureau; Amgen: Consultancy; Janssen: Consultancy; Abbvie: Consultancy; Roche: Consultancy; Jazz Pharmaceuticals: Consultancy. Cavo:Celgene: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau; GlaxoSmithKline: Honoraria, Membership on an entity's Board of Directors or advisory committees; Adaptive Biotechnologies: Honoraria, Membership on an entity's Board of Directors or advisory committees; Amgen: Honoraria, Membership on an entity's Board of Directors or advisory committees; Takeda: Honoraria, Membership on an entity's Board of Directors or advisory committees; AbbVie: Honoraria, Membership on an entity's Board of Directors or advisory committees; Bristol-Myers Squibb: Honoraria, Membership on an entity's Board of Directors or advisory committees; Janssen: Honoraria, Membership on an entity's Board of Directors or advisory committees, Research Funding, Speakers Bureau.

Functional profiling is an emerging trend in precision medicine. Manual laboratory methods proved to be effective in predicting the response to drug treatments both in patients stratified according to genetic profiling and in patients without any specific molecular aberration. In this work, we validated the predictive power of an innovative functional profiling platform, based on lab-on-a-chip technology, which allows testing the response of live tumor cells exposed to anticancer drugs in a fully-automated process, requiring only a Ficoll stratification as a manual step. 15 AML patients (Age: 40% 70 years; Gender: 40% Female; ELN Classification: 20% Favorable, 26% Intermediate-I, 33% Intermediate-II, 14% Adverse; AML stage: 53% De novo, 7% Relapse, 40% Refractory; Treatment: 20% FLAI-3, 40% FLAI-5, 26% Decitabine; 7% Cytarabine, 7% 5-azacitidine) were treated at the Policlinico Sant'Orsola in Bologna. At the same time, bone marrow samples were challenged with the same drugs at scaled concentrations in the functional profiling platform developed by CellPly and an output score was extracted from time-lapse fluorescence image analysis of patient tumor cells exposed to the drug or drug combination for 24 hours. Clinical follow up resulted in the following classification: complete hematologic response (CR) was found in 6/15 patients (6/6 with a De Novo disease), while the remaining 9/15 patients (2/9 de novo; 1/9 Relapse; 6/9 Refractory) were classified as stable disease (SD). In-vitro functional profiling of 14 patients provided a correlation with the clinical outcome (p=0.01) irrespective of the stage of the disease. 100% of the patients identified as responders by functional profiling (n = 5), resulted in a CR outcome. 89% of the patients identified as non-responders (n = 9) resulted in an SD outcome. The same patient samples were also investigated for the molecular assessment of the most relevant genes commonly analyzed in AML patients. FLT3-ITD mutation was found in 2/14 patients, both in SD. Negative FLT3 was not correlated to clinical outcome. FLT3-TKD mutation was found in 3/14 patients, 2/3 resulted in CR, 1/3 in SD. TP53 mutation was found in 1/13 patients, classified as SD. Intronic variant rs1625895 was found in 6/13 patients equally distributed in CR and SD. NPM1 mutation was identified in 4/13 patients, 2/4 resulted in CR, 2/4 in SD indicating no direct correlation. IDH2 was found in 1/11 patients (with R172K mutation) with an SD. As a conclusion, functional profiling proved to be highly correlated with clinical outcome irrespective of patient stage and demonstrated a superior predictive power compared to molecular profiling. Citation Format: Laura Rocchi, Andrea Faenza, Viviana Guadagnuolo, Laura Rambelli, Giovanni Marconi, Maria Chiara Fontana, Martina Pazzaglia, Cristina Papayannidis, Giorgia Simonetti, Nicola Pecorari, Luca Giulianelli, Dario Biscarini, Marco Bettelli, Michele Federici, Rita Ruggiano, Giovanni Martinelli, Roberto Guerrieri, Massimo Bocchi. Lab-on-a-chip-based in-vitro functional profiling proves to be effective in predicting therapy outcome in AML patients [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 3613.