Abstract: Myeloproliferative neoplasms (MPN) that have evolved into accelerated or blast phase disease (MPN-AP/BP) have poor outcomes with limited treatment options and therefore represent an urgent unmet need. We have previously demonstrated in a multicenter, phase 1 trial conducted through the Myeloproliferative Neoplasms Research Consortium that the combination of ruxolitinib and decitabine is safe and tolerable and is associated with a favorable overall survival (OS). In this phase 2 trial, 25 patients with MPN-AP/BP were treated at the recommended phase 2 dose of ruxolitinib 25 mg twice daily for the induction cycle followed by 10 mg twice daily for subsequent cycles in combination with decitabine 20 mg/m2 for 5 consecutive days in a 28-day cycle. Nineteen patients died during the study follow-up. The median OS for all patients on study was 9.5 months (95% confidence interval, 4.3-12.0). Overall response rate (complete remission + incomplete platelet recovery + partial remission) was 11/25 (44%) and response was not associated with improved survival. We conclude that the combination of decitabine and ruxolitinib was well tolerated, demonstrated favorable OS, and represents a therapeutic option for this high-risk patient population. This trial was registered at www.clinicaltrials.gov as #NCT02076191.

Abstract: Therapy-related myelodysplastic syndrome and acute leukemias (t-MDS/AL) are a major cause of nonrelapse mortality among pediatric cancer survivors. Although the presence of clonal hematopoiesis (CH) in adult patients at cancer diagnosis has been implicated in t-MDS/AL, there is limited published literature describing t-MDS/AL development in children. Experimental Design: We performed molecular characterization of 199 serial bone marrow samples from 52 patients treated for high-risk neuroblastoma, including 17 with t-MDS/AL (transformation), 14 with transient cytogenetic abnormalities (transient), and 21 without t-MDS/AL or cytogenetic alterations (neuroblastoma-treated control). We also evaluated for CH in a cohort of 657 pediatric patients with solid tumor. Results: We detected at least one disease-defining alteration in all cases at t-MDS/AL diagnosis, most commonly TP53 mutations and KMT2A rearrangements, including involving two novel partner genes (PRDM10 and DDX6). Backtracking studies identified at least one t-MDS/AL-associated mutation in 13 of 17 patients at a median of 15 months before t-MDS/AL diagnosis (range, 1.3–32.4). In comparison, acquired mutations were infrequent in the transient and control groups (4/14 and 1/21, respectively). The relative risk for development of t-MDS/AL in the presence of an oncogenic mutation was 8.8 for transformation patients compared with transient. Unlike CH in adult oncology patients, TP53 mutations were only detectable after initiation of cancer therapy. Last, only 1% of pediatric patients with solid tumor evaluated had CH involving myeloid genes. Conclusions: These findings demonstrate the clinical relevance of identifying molecular abnormalities in predicting development of t-MDS/AL and should guide the formation of intervention protocols to prevent this complication in high-risk pediatric patients.

Abstract: Background In patients with Myelodysplastic Syndromes (MDS), TP53 mutations associate with high-risk presentation, complex karyotype, acute myeloid leukemia (AML) progression and poor response to hematopoietic stem cell transplantation. These associations highlight the relevance of TP53 as a prognostic and predictive biomarker. Consistent with its role as a tumor suppressor, bi-allelic targeting of the TP53 locus is a frequent but not an obligatory event. Despite the central role of TP53 in MDS, the clinical implications of TP53 mutations in the context of allelic state have not been extensively studied. Methods Under the auspices of the International Working Group for Prognosis in MDS, we sequenced a representative cohort of 3,324 peri-diagnosis MDS patients on a next generation sequencing (NGS) panel optimized for myeloid disease. Conventional G-banding analysis (CBA) was available for 2,931 patients. Focal (~3MB) gains and deletions and regions of NGS-derived copy-neutral loss of heterozygosity (cnLOH) were assessed using an in-house algorithm CNACS. Putative oncogenic mutations in TP53 were characterized by consideration of normal controls and established population databases. A validation cohort of 1,120 samples with independent but comparable molecular and clinical annotation was sourced from a compendium of Japanese MDS data to include JALSG-MDS212, JMDP registry, and regional registries. Results NGS-derived ploidy alterations and CBA show a high genome-wide concordance. From NGS profiles, 11% of patients (n=360) are subject to cnLOH, of which 80 target the TP53 locus. We characterize 490 TP53 mutations in 380 patients, representing 11% of the cohort. Amongst those patients, 22% (n=85) and 21% (n=78) have a deletion or a cnLOH involving the TP53 locus, respectively. Taken together, these segregate patients into two TP53 states: a mono-allelic state where one wild type allele remains (33% of TP53 mutated patients, n=126); and a multi-hit state where TP53 is altered multiple times by either mutations, deletions or cnLOH (67% of TP53 mutated patients, n=254). We find that TP53 state shapes clinical presentation and outcomes. Mono-allelic TP53 patients present with more favorable disease than multi-hit TP53 patients: they are less cytopenic, have lower bone marrow blasts (median 4 vs. 9%, p & lt;0.0001) and are enriched in low risk WHO subtypes. We show that the established association between mutated TP53 and complex karyotype is specific to the multi-hit TP53 state (OR=66, CI: 33-141, p & lt;0.0001). Critically, we show that multi-hit TP53 associates with worse overall survival as compared to mono-allelic TP53 (HR=3.7, CI: 2.7-5.1, p & lt;0.0001; Figure 1a) and more pronounced AML transformation (HR=5.3, CI: 3.1-8.9, p & lt;0.0001; Figure 1b). Patients with mono-allelic TP53 mutations have a similar survival to that of wild type TP53 patients and track overall IPSS-R, whereas multi-hit TP53 stratifies adverse prognostic subgroups independent of the IPSS-R. We formally test this using multivariate models that consider age, peripheral blood counts, blasts and IPSS-R cytogenetic score and show that multi-hit TP53 state is an independent prognostic factor for overall survival and AML transformation, whilst mono-allelic TP53 state is not significant. We also observe a significant difference in overall survival between TP53 states in the context of therapy-related MDS (HR=3.1, CI: 1.2-7.9, p=0.03). Last, analyses of 12 serial samples identify multi-hit targeting of the TP53 locus as a critical driver of AML transformation in the context of TP53-mutated MDS. These findings are replicated in the validation cohort. Conclusions TP53 is a natural candidate for incorporation in molecularly informed risk stratification schemas (molecular IPSS-R). We show that TP53 state rather than mutation alone is an independent diagnostic and prognostic biomarker in MDS. We propose that ascertainment of TP53 state is critical in prospective clinical sequencing for risk estimation, disease monitoring and future correlative research into predictors of response to established and investigational therapies. Disclosures Bernard: Celgene: Research Funding. Hasserjian:Jazz Pharmaceuticals: Consultancy; Promedior, Inc.: Consultancy. Germing:Celgene: Honoraria, Research Funding; Novartis: Honoraria, Research Funding; Jazz Pharmaceuticals: Honoraria; Amgen: Honoraria. Cargo:Celgene: Research Funding. Santini:Acceleron: Membership on an entity's Board of Directors or advisory committees; Amgen: Membership on an entity's Board of Directors or advisory committees; Menarini: Membership on an entity's Board of Directors or advisory committees; Johnson & Johnson: Honoraria; Novartis: Honoraria, Membership on an entity's Board of Directors or advisory committees; Celgene Corporation: Honoraria, Membership on an entity's Board of Directors or advisory committees. Kotsianidis:Celgene: Research Funding. Takaori-Kondo:Pfizer: Honoraria; Chugai: Research Funding; Janssen: Honoraria; Kyowa Kirin: Research Funding; Takeda: Research Funding; Ono: Research Funding; Bristol-Myers Squibb: Honoraria, Research Funding; Celgene: Honoraria, Research Funding; Novartis: Honoraria. Savona:Selvita: Membership on an entity's Board of Directors or advisory committees; Takeda: Membership on an entity's Board of Directors or advisory committees, Research Funding; Karyopharm Therapeutics: Consultancy, Equity Ownership, Membership on an entity's Board of Directors or advisory committees; AbbVie: Membership on an entity's Board of Directors or advisory committees; Boehringer Ingelheim: Patents & Royalties; Celgene Corporation: Membership on an entity's Board of Directors or advisory committees; Incyte Corporation: Membership on an entity's Board of Directors or advisory committees, Research Funding; TG Therapeutics: Membership on an entity's Board of Directors or advisory committees, Research Funding; Sunesis: Research Funding. Ades:Takeda: Membership on an entity's Board of Directors or advisory committees; Novartis: Membership on an entity's Board of Directors or advisory committees; Silence Therapeutics: Membership on an entity's Board of Directors or advisory committees; Celgene: Membership on an entity's Board of Directors or advisory committees; Helsinn Healthcare: Membership on an entity's Board of Directors or advisory committees; Agios: Membership on an entity's Board of Directors or advisory committees; Jazz: 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; Amgen: Research Funding. Neuberg:Pharmacyclics: Research Funding; Madrigal Pharmaceuticals: Equity Ownership; Celgene: Research Funding. Stevenson:Celgene: Research Funding. Fenaux:Jazz: Honoraria, Research Funding; Astex: Honoraria, Research Funding; Aprea: Research Funding; Celgene Corporation: Honoraria, Research Funding. Platzbecker:Novartis: Consultancy, Honoraria; Abbvie: Consultancy, Honoraria; Celgene: Consultancy, Honoraria. Heuser:Synimmune: Research Funding; Bayer Pharma AG, Berlin: Research Funding. Valent:Blueprint: Research Funding; Pfizer: Honoraria; Celgene: Honoraria; Novartis: Consultancy, Honoraria, Research Funding; Deciphera: Honoraria, Research Funding. Miyazaki:Nippon-Shinyaku: Honoraria; Dainippon-Sumitomo: Honoraria; Otsuka: Honoraria; Chugai: Research Funding; Novartis: Honoraria; Kyowa-Kirin: Honoraria. Finelli:Novartis: Consultancy, Speakers Bureau; Celgene Corporation: Consultancy, Research Funding, Speakers Bureau; Janssen: Consultancy, Speakers Bureau. Atsuta:CHUGAI PHARMACEUTICAL CO., LTD.: Honoraria; Kyowa Kirin Co., Ltd: Honoraria. Gattermann:Novartis: Honoraria; Takeda: Research Funding; Alexion: Research Funding. Ebert:Broad Institute: Other: Contributor to a patent filing on this technology that is held by the Broad Institute.; Celgene: Research Funding; Deerfield: Research Funding. Bejar:Celgene: Consultancy; Takeda Pharmaceuticals: Research Funding; AbbVie/Genentech: Consultancy, Honoraria; Astex/Otsuka: Consultancy; Modus Outcomes: Consultancy; Daiichi-Sankyo: Consultancy. Greenberg:Notable Labs: Research Funding; Celgene: Research Funding; Genentech: Research Funding; H3 Biotech: Research Funding; Aprea: Research Funding; Novartis: Membership on an entity's Board of Directors or advisory committees. Ogawa:Qiagen Corporation: Patents & Royalties; ChordiaTherapeutics, Inc.: Consultancy, Equity Ownership; RegCell Corporation: Equity Ownership; Dainippon-Sumitomo Pharmaceutical, Inc.: Research Funding; Kan Research Laboratory, Inc.: Consultancy; Asahi Genomics: Equity Ownership. Papaemmanuil:Celgene: Research Funding.

Abstract: Background: Recapitulation of the full spectrum of genomic changes driving patient tumors have resulted in increased use of patient-derived xenograft (PDX) models in studies of basic cancer biology and preclinical drug development. Given the translational potential of PDXs and limited availability of pediatric cancer models, we established a PDX program to expand the existing collection of pediatric PDXs in the community and enable pre- and post-clinical studies. Methods: PDX generation requests were integrated into clinical workflows to maximize identification of eligible patients for informed consent and tissue collection at Memorial Sloan Kettering Cancer Center. Methodologies for tissue procurement and cryopreservation were optimized to facilitate implantation into host immunodeficient mice and enable multi-institutional tissue exchange for model building. A bioinformatics pipeline was established to allow molecular validation of engrafted PDXs using a next-generation targeted gene panel (MSK-IMPACT) evaluating concordance based on acquired mutations, copy number alterations and clonal structure. Results: Between November 2016 - October 2021, 379 PDX models were developed (265 distinct models) representing 69 discrete diagnoses. Sarcoma represents the most common model type (50 discrete osteosarcoma, 20 desmoplastic small round cell tumor, 14 Ewing sarcoma, 24 rhabdomyosarcoma, 2 CIC/DUX4 and 2 BCOR-rearranged sarcoma) followed by neuroblastoma (n=35), leukemia (n=44), and Wilms tumor (n=15). While the majority of PDXs were established from recurrent or metastatic tissue, 7 paired diagnostic/pre-therapy and post-therapy or relapse models were generated. Genomic characterization of PDXs demonstrate excellent concordance and recapitulation of single nucleotide variants (90%), structural (88%) and copy number variants (94%) between patient tumor and matched PDX. Discrepancies between matched patient/PDX pairs are due to sub-clonal heterogeneity in source tumors with clonal outgrowth in the PDX. Analysis of serial PDX passages also demonstrate stable recapitulation of the genomic profile. Establishment of a diverse PDX collection allowed preclinical evaluation of 10 targeted agents across a spectrum of pediatric tumors and provided the preclinical rationale for 3 investigator-initiated pediatric clinical trials. Conclusions: Investment in the development of a phenotypically diverse and biologically faithful collection of pediatric PDX models enables the goals of precision medicine. Optimization of PDX workflows and methods has also enabled the development of a pediatric PDX consortium (PROXC - Pediatric Research in Oncology Xenografting Consortium) to further support the development of pre- and post-clinical studies for pediatric cancer. Citation Format: Filemon S. Dela Cruz, Joseph G. McCarter, Daoqi You, Nancy Bouvier, Xinyi Wang, Kristina C. Guillan, Armaan H. Siddiquee, Katie B. Souto, Hongyan Li, Teng Gao, Dominik Glodzik, Daniel Diolaiti, Neerav N. Shukla, Joachim Silber, Umeshkumar K. Bhanot, Faruk Erdem Kombak, Diego F. Coutinho, Shanita Li, Juan E. Arango Ossa, Juan S. Medina-Martinez, Michael V. Ortiz, Emily K. Slotkin, Michael D. Kinnaman, Sameer F. Sait, Tara J. O'Donohue, Marissa Mattar, Maximiliano Meneses, Michael P. LaQuaglia, Todd E. Heaton, Justin T. Gerstle, Nicola Fabbri, Chelsey M. Burke, Irene M. Rodriquez-Sanchez, Christine A. Iacobuzio-Donahue, Julia L. Glade Bender, Ryan D. Roberts, Jason T. Yustein, Nino C. Rainusso, Brian D. Crompton, Elizabeth Stewart, Alejandro Sweet-Cordero, Leanne C. Sayles, Andrika D. Thomas, Michael H. Roehrl, Elisa de Stanchina, Elli Papaemmanuil, Andrew L. Kung. Development of a patient-derived xenograft (PDX) modeling program to enable pediatric precision medicine [abstract] . In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 704.

Abstract: Background Therapy-related myelodysplastic syndrome (MDS) and acute leukemias represent a major cause of non-relapse morbidity and mortality in childhood cancer survivors, and have been associated with exposure to cytotoxic therapies (e.g. radiation, alkylators, topoisomerase inhibitors). Neuroblastoma (NB) patients receive multimodality therapy with intensive chemotherapy, radiation, and immunotherapy, and have had high rates of treatment-related leukemias (Kushner, Cheung et al. 1998). Whilst specific therapeutic modalities have been associated with distinct cytogenetic and molecular abnormalities, our understanding of the relationships between timing of mutation acquisition, dynamics of clonal selection in relation to specific therapeutic modalities, and how these in unison result in overt leukemia, remains limited. Motivated to study these relationships and inform future screening guidelines, we characterized serial bone marrow (BM) samples obtained during surveillance for NB recurrence and therapy-related leukemias. Methods We studied a total of 219 serial samples from 55 NB patients treated at MSKCC over a 21-year period. These included 19 patients with MDS or leukemic transformation (median time following NB diagnosis 4.4 years), 15 with transient cytogenetic abnormalities (median time to abnormality 3.1 years), and 21 matched controls (median disease-free follow-up 8.1 years). On average, we analyzed 4 samples per transformation patient, representative of pre-treatment timepoints at NB diagnosis, during NB treatment, and throughout follow-up, with a lead time of 18 years - 1 month prior to transformation, and at time of leukemic transformation. Comprehensive genomic profiling with targeted gene sequencing (MSK-IMPACT Heme), RNA-seq, and Archer FusionPlex was performed to capture acquired gene mutations, chromosome-level copy number alterations (CNA), and fusion genes at the time of diagnosis. Backtracking studies were performed in longitudinal samples with complete molecular and clonal characterization. Results We detected at least one disease-defining alteration in all cases with MDS or leukemic transformation at time of diagnosis, with a total of 61 putative oncogenic events across all patients (median 3 alterations per patient, range 1-12). As expected, the most frequent events were MLL fusions (n=6 patients), and mutations in TP53 (n=5 patients). The remaining cases harbored chromosomal aneuploidies or acquired gene mutations in NPM1, IDH1, PTPN11, NRAS, BCOR, CUX1, STAG2, WT1, amongst other genes, at a median variant allele frequency 24% (range 4-68%). Backtracking studies identified at least one of these mutations in 81% of patients at a sampling time point prior to diagnosis. In contrast, only two patients (2/15) from the cohort with transient cytogenetic abnormalities had acquired somatic mutations detected at a median VAF of 3%, with resolution of the molecular alterations in subsequent samples. One of the control cases also had an identified mutation, though this patient died of NB with limited hematologic follow-up. The median time of detection of a putative driver alteration was 6 months prior to leukemic transformation, with the earliest identified at 2.8 years prior to disease transformation. At least 3 cases of MLL fusions were detected 2.2, 14.5, and 20.9 months prior to diagnosis. Mutations in TP53 co-occurred with CNAs in all patients in our cohort, and has been shown to be predictive of chemoresistant disease. Mutations in TP53 were also identified in at least 2 pre-leukemic samples per patient in 4 of 5 cases, at a median VAF 5% (range 5-20%). In all of these cases, TP53 mutations preceded clinically detectable CNA. Genetic evolution led clonal dominance, which, intriguingly, often preceded disease presentation in the context of normal hematopoeisis. We also found evidence of clonal drifts, possibly as a consequence of treatment effects. Conclusions Our preliminary data demonstrate that NB patients at risk of developing secondary leukemia can be identified by molecular profiling of BM aspirates obtained during routine disease surveillance for NB. These findings present an opportunity for the development of early detection studies for patients with pediatric malignancies undergoing intensive therapy and importantly inform studies into mechanisms of leukemic transformation and specific gene-treatment effects. Disclosures Cheung: Ymabs: Patents & Royalties.

Abstract: Despite a detailed understanding of the genes mutated in myelodysplastic syndromes (MDS), diagnostic and treatment decisions for patients with MDS rely primarily on clinical and cytogenetic variables as considered by the Revised International Prognostic Scoring System (IPSS-R). Here we describe the recently developed Molecular IPSS (IPSS-M), a clinico-genomic risk stratification system that considers clinical, cytogenetic and genetic parameters; the implementation of a web portal to facilitate its adoption, a strategy to handle missing variables, and the worldwide utilization of the web calculator as a clinical support tool. The IPSS-M was trained on 2,957 clinically annotated diagnostic MDS samples profiled for mutations in 156 driver genes. To maximize the clinical applicability of the IPSS-M and account for missing genetic data (i.e genes missing from a sequencing panel), we implemented a strategy to calculate a risk score under three scenarios: best, worst and average. Last, we developed an online calculator as a standalone single-page web application using VueJs, and D3Js for the interactive visualizations, deployed through a CI/CD pipeline on AWS, where collection of anonymous usage analytics allows to track adoption and usability of the new proposed model. The model incorporates clinical, morphological, genetic variables informed by cytogenetics and constructed from the presence of oncogenic mutations in 31 genes. It delivers a unique risk score for each individual patient, as well as an assignment to one of six IPSS-M risk strata. Compared to the IPSS-R the IPSS-M re-stratified 46% of MDS patients. The model was validated in an external dataset of 754 MDS patients. We released an open-access IPSS-M web calculator available at https://mds-risk-model.com. By specifying the patient clinical and molecular profiles, the tool returns the patient-specific IPSS-M risk score and category, and the probability estimates over time for three clinical endpoints, i.e. leukemia free survival (LFS), overall survival, and incidence of leukemic transformation. Since its launch in June 2022, the calculator has been used by & gt;6000 users in & gt;75 countries, reaching a daily average of 100 users per day. Risks have been calculated for & gt;45,000 patient profiles. 99.28% of the sessions initiated reach an IPSS-M score, suggesting that the calculator is intuitive and easy to use. We trained and validated the IPSS-M on 3,711 patients, a patient tailored risk stratification tool for patients with MDS that considers clinical, morphological and genetic variables inclusive of cytogenetics and mutations in one of 31 genes. The development of a web based tool was instrumental to the global dissemination of the model, enabling non-expert users to leverage the power of molecular biomarkers in risk stratification for patients with MDS. Citation Format: Elsa Bernard, Juan E. Arango Ossa, Heinz Tuechler, Peter L. Greenberg, Robert P. Hasserjian, Yasuhito Nannya, Sean M. Devlin, Maria Creignou, Philippe Pinel, Lily Monier, Juan S. Medina-Martinez, Dylan Domenico, Martin Jädersten, Ulrich Germing, Guillermo Sanz, Arjan A. van de Loosdrecht, Olivier Kosmider, Matilde Y. Follo, Felicitas Thol, Lurdes Zamora, Ronald F. Pinheiro, Andrea Pellagatti, Detlef Haase, Pierre Fenaux, Monika Belickova, Michael R. Savona, Virginia M. Klimek, Fabio P. Santos, Jacqueline Boultwood, Ioannis Kotsianidis, Valeria Santini, Francesc Solé, Uwe Platzbecker, Michael Heuser, Peter Valent, Kazuma Ohyashiki, Carlo Finelli, Maria Teresa Voso, Lee-Yung Shih, Michaela Fontenay, Joop H. Jansen, José Cervera, Norbert Gattermann, Benjamin L. Ebert, Rafael Bejar, Luca Malcovati, Mario Cazzola, Seishi Ogawa, Eva Hellström-Lindberg, Elli Papaemmanuil. Implementation and adoption of a web tool to support precision diagnostic and treatment decisions for patient with myelodysplastic syndromes [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6168.

Abstract: Genome profiling represents a critical pillar for clinical, translational, and basic research studies. Hospitals, core facilities, and research enterprises invest significant resources to generate genomic data sets. Yet, data management and analysis is frequently manual, which demands significant operator time and often results in siloed resources rendering them as single-use assets. Centralization of the genomic capital in a framework that enables automated processing, metadata integration and continuous interrogation maximizes return for investment and serves as the critical catalyst for research innovation, clinical translation and reproducible research. We developed Isabl, a plug-and-play infrastructure for scalable bioinformatics operations. Isabl provides solutions for databasing, assets management, tracking, automated and reproducible data processing. Dynamic reporting and meta-analysis across data assets is enabled. Isabl is built on four main components. First, an individual-centric and extensible relational database with tracking support for samples (temporal, spatial, aliquot), experimental data (assays, platforms, sequencing runs), cohorts (clinical trials, research projects) and versioned bioinformatics applications (assembly aware, tools, results). Second, the database is exposed through a fully featured RESTful API that enables horizontal integration with information systems such as sequencing cores LIMS, variant visualization platforms like cBioPortal, and where applicable, clinical and biospecimen institutional databases. Third, a Software Development Kit (SDK) built for Next Generation Sequencing assets management. The SDK enables automated execution of data import and language-agnostic bioinformatics applications (alignment, variant calling, post-processing) with support for cohort and individual level reporting features. Furthermore, the SDK facilitates dynamic retrieval of results using vertical and horizontal queries (individual and cohort level, respectively). Lastly, Isabl comes with a Single Page Web Application that fosters user interaction with multidisciplinary teams (i.e. researchers, project coordinators, engineers, clinicians) facilitating tracking of analyses, results visualization, and dynamic query processing. Isabl is currently supporting the Memorial Sloan Kettering Genome Pediatrics Precision Medicine Initiative, a prototype platform that delivers integrated, real-time automated reporting of clinical targeted gene re-sequencing, research whole genome and transcriptome profiling data; as well as linked data from pre-clinical models (i.e. PDX) and single cells studies. As an open-source tool, Isabl democratizes access to a purpose built, automated, scalable and fully integrable bioinformatics architecture. Isabl will be available at https://github.com/isabl-io. Citation Format: Juan S. Medina-Martínez, Juan E. Arango-Ossa, Gunes Gundem, Max F. Levine, Minal Patel, Noushin R. Farnoud, Venkata D. Yellapantula, Gao Teng, Joseph G. Mccarter, Elsa Bernard, Franck Rapaport, Dominik Glodzik, Ross L. Levine, Andrew Kung, Elli Papaemmanuil. A plug-and-play infrastructure for scalable bioinformatics operations [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 5105.

Abstract: Background Stably acquired mutations in hematopoietic cells represent substrates of selection that may lead to clonal hematopoiesis (CH), a common state in cancer patients that is associated with a heightened risk of leukemia development. Owing to technical and sample size limitations most CH studies have characterized gene mutations or mosaic chromosomal alterations (mCAs) individually. The relationship between acquired gene mutations and mCAs in CH and their joint roles in leukemia development have not been systematically investigated. Methods We developed a method to reliably map mCAs at low cell fractions from deep targeted sequencing data. We applied this method in a cohort of 32,442 solid tumor patients who have undergone prospective clinical sequencing (MSK-IMPACT). We characterized gene mutations in our patient cohort using an established variant calling procedure from our previous studies. Results We jointly characterized 383 mCA events (median aberrant cell fraction 32%, range 10%-90%) and 14,789 mutations across 457 genes. mCA was significantly associated with age (OR=1.8, P & lt;0.001), male gender (OR=1.4, P=0.012), white race (OR=1.5, P=0.033) and prior receipt of external beam radiation therapy (OR=1.7, P=0.022). 217 (63%) mCAs co-occurred with at least one gene mutation, while 129 (37%) did not (OR=3.9, P & lt;0.001). mCA was especially enriched in CH cases with high mutation number and VAF, detectable in 5.8% of subjects with ≥3 gene mutations and 4.8% of those with mutations at & gt;20% VAF, compared to 1% of the general cohort. We identify co-mutational patterns characteristic of diverse mechanisms of clonal selection. We observe that mutations in DNMT3A, TET2, JAK2, MPL, EZH2, TP53 and ATM form recurrent double-hits with deletions or CNLOHs, resulting in either oncogene mutant dosage adjustment or inactivation of tumor suppressors. Notably, certain mCA events were highly directed events acting on previously acquired gene mutations in the corresponding loci. Of six events of 7qCNLOH, all six co-localized with an EZH2 (7q36.1) mutation (q & lt;0.001). Of 12 cases with 9pCNLOH, 11 (92%, q & lt;0.001) co-localized with a JAK2 V617F mutation. 4 out of 9 (44%, q & lt;0.001) 1pCNLOH events co-localized with a MPL (1p34.2) mutation. In addition, we observe recurrent composite genotypes (4q24-/SRSF2, 7qCNLOH/ASXL1, 20q-/U2AF1) indicative of co-operating or epistatic interactions as well as loss of gatekeeper function (i.e. TP53) presenting with multiple chromosomal aneuploidies (5-, 7-, 3+). In total, these recurrent composite genotypes resembling known genetic interactions in leukemia genomes underlie 23% of all detected autosomal mCAs. During patient follow-up, the 3-year cumulative incidence of leukemias was significantly higher in patients with composite CH genotypes (14.6%, CI: 7-22%) as compared to patients with either mCA, gene mutation alone or no CH, of which all had a 3-year cumulative incidence of & lt;1% (Figure 1). We performed a multivariable cause-specific Cox regression model and showed that mCA was independently predictive of subsequent leukemia diagnosis (HR=14, 95% CI: 6-33, P=1.2e-09) after adjusting for number of gene mutations and VAF in putative drivers. Conclusions Our joint characterization of gene mutations and mCAs in a large prospective sequencing cohort reveals a previously unrecognized layer of complexity in the evolutionary dynamics of clonal hematopoiesis that converges towards characteristic genotypes associated with distinct leukemia subtypes. This puts mCAs in the context of the continuous evolutionary process of oncogenesis that can often span years and sheds new lights on its patterns of acquisition and progression. We demonstrate that the integration of chromosomal aberrations provides additional resolution to risk stratification as well as interpretation of clinical phenotypes and that mCAs should be screened in conjunction with gene mutations to improve existing CH surveillance programs in cancer patients. Disclosures Bolton: GRAIL: Research Funding. Medina:Isabl: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Mantha:MJH Associates: Honoraria; Physicians Education Resource: Honoraria. Solit:Pfizer: Honoraria; Loxo Oncology: Honoraria; Lilly Oncology: Honoraria; Illumina: Honoraria; Vivideon Therapeutics: Honoraria. Diaz:Neophore: Consultancy, Current equity holder in private company; Merck: Consultancy; Johns Hopkins University: Patents & Royalties; Jounce Therapeutics: Current equity holder in private company; Thrive Earlier Detection: Current equity holder in private company; Personal Genome Diagnostics: Consultancy, Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees. Berger:Illumina: Research Funding; Roche: Consultancy; Grail: Research Funding. Levine:Lilly: Consultancy, Honoraria; Janssen: Consultancy; Roche: Consultancy, Honoraria, Research Funding; Loxo: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Imago: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; C4 Therapeutics: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Isoplexis: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; Celgene: Consultancy, Honoraria, Research Funding; Prelude Therapeutics: Research Funding; Gilead: Honoraria; Amgen: Honoraria; Morphosys: Consultancy; Novartis: Consultancy; Astellas: Consultancy; Qiagen: Current equity holder in publicly-traded company, Membership on an entity's Board of Directors or advisory committees. Zehir:Memorial Sloan Kettering Cancer Center: Current Employment; Illumina: Honoraria. Papaemmanuil:Celgene: Consultancy, Honoraria, Research Funding; Prime Oncology: Consultancy, Honoraria; Novartis: Consultancy, Honoraria; Illumina: Consultancy, Honoraria; Kyowa Hakko Kirin: Consultancy, Honoraria; Isabl: Current equity holder in private company, Membership on an entity's Board of Directors or advisory committees; MSKCC: Patents & Royalties.