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• Beyond BRCA deficiency: Clinical and molecular predictors of survival in patients with BRCA-deficient tubo-ovarian high-grade serous carcinoma

  Homologous recombination DNA repair deficient (HRD) tumors account for about 50% of tubo-ovarian high-grade serous carcinomas (HGSC) and are associated with a high response to platinum-based chemotherapy. However, a subset of patients with HRD tumors have unexpected resistance to chemotherapy and experience short survival. Our study compared BRCA-deficient and proficient HGSC among patients with short (<3 years, the lowest quartile of overall survival (OS)) versus longer-term (>3 year OS) to identify prognostic markers and potential therapeutic opportunities. Primary tumors from a cohort of patients with advanced-stage HGSC (n=154) enriched for those with HRD tumors and short survival (n=42) were analyzed using whole-genome sequencing, bulk RNA-sequencing, and DNA methylation profiling. A subset of HRD tumors (n=143) were characterized for immune cell densities by multiplex immunofluorescence. Clinicopathological features were assessed in 1,389 patients with HGSC, including 282 with pathogenic germline BRCA variants (gBRCApv). Findings were validated in two international HGSC cohorts: the Ovarian Tumor Tissue Analysis consortium (n=5,875) and Multisciplinary Ovarian Cancer Outcome Group (n=895). In gBRCApv-carriers, residual disease following surgical cytoreduction was not associated with shorter OS unlike in non-carriers where it was strongly associated. While most patients with gBRCApv had a more favorable OS compared to non-carriers, a survival advantage was not apparent in those with variants located outside of BRCA1 exon 10/23 and BRCA2 exon 11/27. Patient survival correlated with HRD score, such that those with a score ≥63 had significantly longer OS compared to those with HRD scores of 42-63 and <42. While higher HRD scores were associated with better survival outcomes, most gBRCApv carriers with a short survival had tumor HRD scores that exceeded the threshold typically considered predictive of a good response to carboplatin or PARP inhibitors. BRCA2-deficient HGSC with loss of the tumor suppressor NF1 was associated with exceptionally favorable outcome (median OS 17 years), whereas amplification of both PIK3CA and RAD21, was associated with poor outcome in BRCA2-deficient HGSC (median OS 2.9 years). The density of tumor-infiltrating CD8+ PD-1+ T cells was prognostic for OS in gBRCApv-carriers. In summary, rather than simply the presence or absence of a germline BRCA pathological variant influencing patient survival, the co-occurrence of specific somatic gene alterations, the extent of immune cell infiltration, the level of homologous recombination deficiency, and BRCA-variant location may modify clinical outcomes in patients with BRCA-deficient HGSC. Analysis of exceptional outcome patients, in this case gBRCApv-carriers with an atypically short survival, may identify determinants of outcome applicable to the wider HGSC patient population.

  Study EGAS00001008059

• Duplex sequencing

  A total of 387 buccal swab samples were subjected to error-corrected sequencing (duplex sequencing).

  Study EGAS50000000054

• DETECT-A protein data

  This dataset includes all protein biomarker measurements from the DETECT-A study. All protein biomarkers were evaluated with Luminex bead-based immunoassays obtained from Millipore.

  Dataset EGAD50000000444

• iRHOM2 Deficiency Causes Environmentally Directed Immunodysregulatory Disease

  We have conducted a study of two kindreds each with a unique mutation in the gene RHBDF2 that encodes the protein iRHOM2. Whole exome (kindred 1) and whole genome sequencing (kindred 2) have uncovered the first human loss-of-function mutations of RHBDF2 in 4 individuals. The affected patients are all children, 8 years old or younger, and were brought to our attention initially due to their suffering recurrent infections. Sequencing of their family members revealed parents with heterozygous RHBDF2 mutations, and heterozygous and wild type siblings – all of which were unaffected by this disease. A comprehensive investigation of this gene mutation through in vivo and in vitro experiments revealed that a loss of the protein iRHOM2 impairs the activity of the protease ADAM17 and subsequently compromises immune responses. This condition leads to the afflicted patients becoming vulnerable to different infections based on their unique environment and presenting with diverse clinical phenotypes. 

  Study phs002478

• Structurally Complex Osteosarcoma Genomes Exhibit Limited Heterogeneity within Individual Tumors and across Evolutionary Time

  A key characteristic of osteosarcoma is extensive and complex genomic rearrangements. However, published models explaining how these genomic rearrangements occur disagree about if these rearrangements occur early in tumor progression and then are stable afterwards, or if there is ongoing genomic instability. Previous studies have employed bulk sequencing technologies to characterize genomic alterations. A limitation of this approach is that it averages all changes within the bulk sample, essentially masking intra-sample heterogeneity and making evaluation of ongoing genomic instability difficult. To overcome this limitation and compliment previous work, we utilized single-cell whole genome sequencing to quantify somatic copy number alterations (SCNA). By interrogating individual cells within a sample, we were able to examine intra-sample heterogeneity. We found that the SCNA patterns between cells within a single sample were remarkably consistent, which supports the concept that the genomes of osteosarcoma tumors are relatively stable after early genome fragmentation events.

  Study phs003209

• Genomics and Methylation of Neuroendocrine Prostate Cancer from cfDNA (Cornell/Trento 2019)

  A subset of castration resistant prostate cancers develop small cell neuroendocrine prostate cancer (NEPC) as a mechanism of treatment resistance. Metastatic tissue biopsies to evaluate for NEPC transformation are invasive and challenging to perform serially. We performed whole exome and whole genome bisulfite sequencing of plasma cfDNA and matched tumor biopsy samples from 62 patients with metastatic prostate cancer along the disease spectrum to evaluate for NEPC associated genomic and epigenomic features. Multiple tissue biopsies and/or plasma time points were included for a subset of patients to characterize disease heterogeneity and dynamic changes. Computational analysis of clonality and allele specific quantification allowed for detailed comparison of matched tumor tissue and cfDNA data (CLONET v2). Methylation profiles detected from tissue and plasma data were compared and NEPC specific alterations were evaluated in cfDNA. The study supports the feasibility of a plasma based assay for the detection of NEPC.

  Study phs001752

• Childhood Cancer Data Initiative (CCDI): Integrating Longitudinal Clinical, Sociodemographic and Genomic Data into the NCCR

  The goal of this study is to contribute clinical and genomic data from a large institutional cohort of pediatric cancer patients who had tumor genomic profiling between 2013 and 2019 at Dana-Farber/Boston Children's Hospital Cancer and Blood Disorders Center. Clinical data include demographics, diagnosis (classified according to the International Classification of Diseases for Oncology (ICD-O-3.2), stage, and biospecimen associated data. Tumors were sequenced with OncoPanel, a targeted next-generation DNA sequencing panel of up to 447 cancer genes for detection of single-nucleotide variants (SNV), insertions, and deletions, and copy number alterations (CNA), as well as selected intronic regions for up to 60 genes for the detection of structural variants (SV). This dataset includes a patient and sample identifier (GENIE ID) that can be used to link the genomic data included in this dataset to additional longitudinal clinical cancer data on a subset of patients that was submitted to the National Childhood Cancer Registry (NCCR).

  Study phs002677

• Functional Genomic Landscape of Acute Myeloid Leukemia

  The implementation of targeted therapies for acute myeloid leukemia has been challenged by complex mutational patterns within and across patients as well as a dearth of pharmacologic agents for most mutational events. The initial findings from the Beat AML program were from a cohort of 672 tumor specimens collected from 562 patients. Additional patients have been added in subsequent versions. We assessed these specimens using whole exome sequencing, RNA-sequencing, and ex vivo drug sensitivity analyses. Our data reveal novel mutational events not previously detected in AML. We show association of drug response with mutational status, including instances of drug sensitivity that are specific to combinatorial mutational events. Integration with RNA-sequencing also revealed gene expression signatures, which predict a role of specific gene networks in drug response. Collectively, this report offers a dataset, accessible by the Beat AML data viewer (www.vizome.org), that can be leveraged to address clinical, genomic, transcriptomic, and functional inquiries into the biology of AML.

  Study phs001657

• Multiplexing cortical brain organoids for the longitudinal dissection of developmental traits at single cell resolution

  Dissecting human neurobiology at high resolution and with mechanistic precision requires a major leap in scalability, given the need for experimental designs to multiple individuals and, prospectively, population cohorts. To lay the foundation for this, we have implemented and benchmarked complementary strategies to multiplex brain organoids by pooling cells from different pluripotent stem cell lines (PSC) either during organoid generation (mosaic models) or before single cell-RNAseq library preparation (downstream multiplexing). We have also developed a new computational method, SCanSNP, and a consensus call to deconvolve cell identities, overcoming current criticalities in doublets prediction and low quality cells identification. We validated both multiplexing methods for charting neurodevelopmental trajectories at high resolution, thus linking specificity to genetic variation. Finally, we modelled their scalability across different multiplexing combinations and showed that mosaic organoids represent an enabling method for high-throughput settings. Together, this multiplexing suite of experimental and computational methods provides a highly scalable resource for disease modelling.

  Study EGAS50000000698

• 1000 Genomes Used for Cloud Testing

  WARNING: This is a test data set. The phenotype data was not checked to match 1000 Genomes project. Use with caution.This study provides public access to a demonstration subset of 1000 genomes sequence data in dbGaP. It is intended to be used by software developers who design, implement and validate pipelines for dbGaP data. While this project distributes only public data, it uses dbGaP security mechanisms which include a project-specific security key and a decryption password. Since the data are public, the key and password for this project will be included by SRA into public demonstration packages that permit users to test and validate the security of their computational pipelines. Note that all public users of this data will be logged under the same project and account ID. The datasets attached to this project must be restricted to 1000 Genomes data identical to the project's public FTP site. To access these test data using SRA toolkit use prj_phs710EA_test.ngc.

  Study phs000710

• Uncovering Gene Regulatory Differences between Human and Chimpanzee Neural Cells

  A major challenge in human evolutionary biology is to pinpoint the genetic differences that underlie phenotypic changes in the human lineage, such as increased neuron number and a prolonged period of neuronal maturation. Here, we used human-chimpanzee tetraploid cells to distinguish changes in gene expression due to cis-acting sequence variants that change local gene regulation, from trans expression changes due to species differences in the cellular environment, in neural progenitor cells and excitatory neurons using RNA-seq and ATAC-seq. Using a CRISPR inhibition screen with scRNA-seq, transcription factor motif analyses with CUT&Tag, and downstream single-locus studies with RNA-seq, we further characterized cis-acting gene regulatory differences, including changes to FOS, TNIK, FOSL2, and MAZ, that influence neurogenesis and neuronal maturation. This study identifies specific genomic changes that may contribute to human neural specializations and provides a general framework for understanding genetic differences that underlie human traits.

  Study phs004053

• Identification and characterization of molecular markers in aging and neuronal disorders

  Supercentenarians, people who have reached 110 years of age, are a great model of healthy aging. Their characteristics of delayed onset of age-related diseases and compression of morbidity imply that their immune system remains functional. We performed single-cell transcriptome analysis of peripheral blood mononuclear cells (PBMCs), derived from supercentenarians and younger controls. We identified a marked increase of cytotoxic CD4 T-cells (CD4 CTLs) as a novel signature of supercentenarians. Furthermore, single-cell T-cell receptor sequencing of two supercentenarians revealed that CD4 CTLs had accumulated through massive clonal expansion. The CD4 CTLs exhibited substantial heterogeneity in their degree of cytotoxicity as well as a nearly identical transcriptome to that of CD8 CTLs. This indicates that CD4 CTLs utilize the transcriptional program of the CD8 lineage while retaining CD4 expression. Our study reveals that supercentenarians have unique characteristics in their circulating lymphocytes, which may represent an essential adaptation to achieve exceptional longevity by sustaining immune responses to infections and diseases.

  Study JGAS000230

• Motif-directed chromatin repression by BCL11B shapes ectopic targeting and lineage commitment

  BCL11B encodes a critical T-lineage transcription factor that is implicated as both an oncogene and a tumor suppressor in acute leukemia. Despite its central role in development and malignancy, a basic understanding of the sequence determinants of BCL11B activity remains obscure. Here, we define two functionally distinct modes of BCL11B engagement with chromatin: Most detectable BCL11B binding events are determined by pre-existing patterns of chromatin accessibility and RUNX1 occupancy. In contrast, BCL11B directs chromatin closing at genomic regions enriched for DNA motifs containing the core “TGACC” sequence, which are most prevalent in non-T lineages. These BCL11B-closed target sites cannot be identified from conventional BCL11B chromatin profiling approaches yet represent the primary mechanism by which BCL11B regulates gene expression. We provide evidence that cell of origin impacts the ability of BCL11B to repress lineage-inappropriate gene programs, thereby promoting lineage skewing. Together, these findings define a motif-centered determinant of BCL11B repression and explain how BCL11B controls lineage specification.

  Study EGAS50000001719

• Single-cell Analysis of Neoplastic Plasma Cells Identifies Myeloma Pathobiology Mediators and Potential Targets

  Multiple myeloma is a clonal plasma cell (PC) dyscrasia that arises from precursors and has been studied utilizing approaches focused on CD138+ cells. By combining single-cell (sc)RNA- with scB-cell receptor (BCR)-sequencing, we differentiate monoclonal/neoplastic from polyclonal/normal PCs, and find more dysregulated genes, especially in precursor patients, than by analyzing bulk PCs. To determine if this approach can identify oncogenes that contribute to disease pathobiology, MAD2L1 and MAT2A are validated as targets with drug-like molecules that suppress myeloma growth in pre-clinical models. Moreover, functional studies show a role of LAMP5, which is uniquely expressed in neoplastic PCs, in tumor progression and aggressiveness via interactions with c-MYC. Finally, a monoclonal antibody recognizing cell-surface LAMP5 shows efficacy as an antibody-drug conjugate and in a chimeric antigen receptor-guided T-cell format. These studies provide additional insights into myeloma biology and identify potential targeted therapeutic approaches that can be applied to reverse myeloma progression.

  Study EGAS50000000802

• ucfDNA workflows for molecular profiling of malignant disease

  Urinary cell-free DNA (ucfDNA) is a promising liquid biopsy analyte obtained by a non-invasive sampling method, particularly valuable in urological cancers due to the proximity of biofluids to the tumor site. However, extremely high fragmentation and low abundance of ucfDNA pose significant analytical challenges. Improper handling and storage can severely affect ucfDNA quality, necessitating optimized pre-analytical workflows for clinical applications. We evaluated multiple pre-analytical workflows, including urine stabilization approaches against unstabilized urine samples. Our results demonstrated that without stabilization, ucfDNA degraded rapidly and minimal quantities remaining after 72 hours. In contrast, urine stabilization preserved ucfDNA integrity, enabling successful downstream analyses, including digital PCR and next-generation sequencing, for mutation detection in cancer-related genes and genome wide copy number profiling. These findings underscore the critical role of stabilization for a reliable ucfDNA analysis and highlight its potential in molecular diagnostics as a complementary tool to plasma-based liquid biopsies.

  Study EGAS50000001093

• Origination of Ovarian Cancer is Dependent on Specific Aneuploidy Landscape

  Ovarian high-grade serous carcinoma (HGSC), a highly chromosomally instable malignancy, develops through sequential stages of precursors in fallopian tubes including histologically unremarkable but TP53 mutated clones (p53 signature) and serous tubal intraepithelial carcinoma (STIC). Here, we applied RealSeqS to assess aneuploidy in 127 microdissected tubal regions. We found nearly all p53 signatures lost the entire Chr17 chromosome, offering a “two-hit” mechanism of both TP53 and BRCA1 in BRCA1 germline mutation carriers. Proliferatively active STICs harbor gains of 19q12 (CCNE1), 19q13.2, 8q24 (MYCyc), or 8q arm, while proliferatively dormant STICs show 22q loss. Based on aneuploidy patterns in a training set (n= 67), we developed an algorithm, REAL-FAST, to classify NFTE and STICs into 5 clusters. In an independent validation set (n= 72), REAL-FAST was able to detect STIC/HGSC with high sensitivity and specificity. Taken together, REAL-FAST promises a molecular test for diagnosing HGSC precursor lesions based on specific aneuploidy patterns.

  Study EGAS00001007220

• Exome sequencing in HIV+ Viremic Non-Progressors (VNPs) and HIV+ Progressors

  Viremic Non-Progressors (VNPs) maintain normal CD4+ T-cell counts despite uncontrolled HIV-1 replication, but mechanisms leading to CD4+ T-cell preservation are incompletely characterized. We aim to generate a comprehensive understanding of this infrequent phenotype by comparing rates of cellular infection, immunophenotype, genomics, single-cell transcriptomics, metabolomics, and levels of plasma biomarkers in 16 VNPs and 29 HIV+ Progressors. During chronic infection VNPs show lower frequency of HIV-1-infected cells in periphery, which is associated with reduced CCR5 expression and higher prevalence of CCR5Δ32 heterozygosity. The CD8+ T-cell compartment displays a less cytotoxic and less activated phenotype in VNPs. Moreover, despite similar viremia, we found lower bystander CD4+ T-cell death in the VNPs, together with weaker IFN responses, reduced plasma levels of zonulin (a biomarker of intestinal permeability), altered tryptophan catabolism, and preserved LPS responsiveness in vitro. Overall, a complex multifactorial mechanism, suggesting gut-associated lymphoid tissue preservation, underlies resistance to HIV pathogenesis in VNPs.

  Study EGAS50000000079

• Oncogenic FOXL2C134W has gain-of-function chromatin remodeling activity that reprograms glucocorticoid receptor occupancy to promote ovarian granulosa cell tumor growth

  Adult type ovarian granulosa cell tumors (AGCTs) are rare malignancies with near universal somatic mutation c.C402G (p.Cys134Trp) in FOXL2, a forkhead box-family transcription factor important for ovarian function. Relapsed AGCT is incurable and the mechanism of the unique FOXL2 mutation remains incompletely understood. To identify FOXL2C134W-dependent pharmacologic synergies, we created and characterized endogenous FOXL2 isogenic AGCT cells and an AGCT tumoroid biobank. A drug screen identified that glucocorticoids promote FOXL2C134W-dependent AGCT growth. Epigenetic investigation revealed that the Cys134Trp mutation exposes latent DNA sequence-specific pioneering activity in FOXL2, a unique oncogenic mechanism. FOXL2C134W pioneering activity redirects glucocorticoid receptor chromatin occupancy to drive hyaluronan synthase 2 gene expression and increase extracellular hyaluronan secretion. Treatment of AGCT models with hyaluronidase reduces viability and this effect can be rescued by dexamethasone. Thus, gain-of-function pioneering activity contributes to the oncogenic mechanism of FOXL2C134W and creates a potentially targetable synergy with glucocorticoid signaling.

  Study EGAS50000000622

• Whole_genome_sequencing_in_a_multiplex_Crohn_s_disease_family

  In 2009 we identified a four-generation family with over 700 members and 41 affected with Crohn's disease (CD). At the time we sequenced the exome of 6 affected individuals but did not identify any coding variants which appear to explain the high prevalence of disease. Since then we have collected DNA from a large number of additional family members, genotyped linkage arrays on the entire family to refine genomic regions shared by identity by descent and genotyped affected and unaffected members at known CD risk loci identified by Genome Wide Association Studies (GWAS). These analyses have confirmed that a significant unexplained excess of disease remains after accounting for all known genetic factors, and that several regions of the genome are shared by a large fraction of affected individuals. We therefore perform whole genomes sequencing from 8 individuals which will allow us to impute the complete sequence of nearly all the members of the two largest and most severely affected branches of the family.

  Study EGAS00001000060

• Engineering large chromosomal deletions by CRISPR-Cas9

  Arm-level chromosomal deletions are a prevalent and defining feature of cancer. A high degree of tumor-type and subtype specific recurrencies suggest a selective oncogenic advantage. However, due to their large size it has been difficult to pinpoint the oncogenic drivers that confer this advantage. Suitable functional genomics approaches to study the oncogenic driving capacity of arm-level deletions are limited. Here we present an effective technique to engineer arm-level deletions by CRISPR-Cas9 and create isogenic cell line models. We simultaneously induce double-strand breaks (DSBs) at two ends of a chromosomal arm and select the cells that have lost the intermittent region. Using this technique, we induced arm-level deletions on chromosome 11q (65 MB) and chromosome 6q (53 MB) in neuroblastoma cell lines. Such isogenic models enable further research on the role of arm-level deletions in tumor development and growth, and their possible therapeutic potential.

  Study EGAS00001005134

• Repli-seq data for 'Replication timing alterations are associated with mutation acquisition during tumour evolution in breast and lung cancer'

  The essential process of DNA replication timing during each cell cycle is highly regulated ensuring the correct duplication of the genome. The extent and importance of alterations in this process during malignant transformation has not been extensively explored. Here, we evaluate the impact of altered replication timing (ART) on cancer evolution by analysing replication-timing sequencing of cancer and normal cell lines and 952 whole-genome sequenced lung and breast tumours. We find 6%-18% of the cancer genome displays ART. Genomic regions with a change from early to late replication exhibit an increased mutation rate and distinct mutational signatures, while regions changing from late to early contain genes with increased expression and present a preponderance of APOBEC3-mediated mutation clusters and associated driver mutations. We demonstrate that ART is a relatively early event during cancer evolution and that ART may have a stronger correlation with mutation acquisition than alterations in chromatin structure.

  Study EGAS00001007773

• Serial assessment of measurable residual disease in medulloblastoma liquid biopsies

  Nearly one-third of children with medulloblastoma, a malignant embryonal tumor of the cerebellum, succumb to their disease. Conventional response monitoring by imaging and cerebrospinal fluid (CSF) cytology remains challenging and a marker for measurable residual disease (MRD) is lacking. Here, we show the clinical utility of CSF-derived cell-free DNA (cfDNA) as a biomarker of MRD in serial samples collected from children with medulloblastoma (123 patients, 476 samples) enrolled on a prospective trial. Using low-coverage whole-genome sequencing, tumor-associated copy-number variations (CNVs) in CSF-derived cfDNA are investigated as an MRD surrogate. MRD is detected at baseline in 85% and 54% of patients with metastatic and localized disease, respectively. The number of MRD-positive patients decline with therapy, yet those with persistent MRD have significantly higher risk of progression. Importantly, MRD detection precedes radiographic progression in half who relapse. Our findings advocate for the prospective assessment of CSF-derived liquid biopsies in future trials for medulloblastoma.

  Study EGAS00001005592

• SMARCB1 loss activates patient-specific distal oncogenic enhancers in malignant rhabdoid tumors

  Malignant rhabdoid tumor (MRT) is a highly malignant and often lethal childhood cancer. MRTs are genetically defined by bi-allelic inactivating mutations in SMARCB1, a member of the BRG1/BRM-associated factors (BAF) chromatin remodeling complex. Mutations in BAF complex members are common in human cancer, yet their contribution to tumorigenesis remains in many cases poorly understood. Here, we studied derailed regulatory landscapes as a consequence of SMARCB1 loss in the context of MRT. Our multi-omics approach on patient-derived MRT organoids revealed a dramatic reshaping of the regulatory landscape upon SMARCB1 reconstitution. Chromosome conformation capture experiments subsequently revealed patient-specific looping of distal enhancer regions with the promoter of the MYC oncogene. This intertumoral heterogeneity in MYC enhancer utilization is also present in patient MRT tissues as shown by combined single-cell RNA-seq and ATAC-seq. We show that loss of SMARCB1 drives patient-specific epigenetic reprogramming underlying MRT tumorigenesis.

  Study EGAS00001007590

• Genome-wide Rare Variant Score Associates With Morphological Subtypes of Autism Spectrum Disorder

  Defining different genetic subtypes of Autism Spectrum Disorder (ASD) can help predict developmental outcomes. Based on minor physical and major congenital anomalies, we categorized 325 Canadian children with ASD into dysmorphic and non-dysmorphic subgroupings. We developed a method to calculate a genome-wide rare variant score (GRVS) from whole-genome sequencing (WGS) data for each ASD proband. GRVS is a sum of the number of variants in morphology-associated coding and non-coding regions, weighted by their effect sizes. Probands with dysmorphic ASD had a significantly higher GRVS compared to those with non-dysmorphic ASD (P= 0.027). Using the polygenic transmission disequilibrium test, we observed an over-transmission of ASD-associated common variants in non-dysmorphic ASD probands (P= 2.9×10-3). We replicated our findings using 442 ASD probands that had accompanying morphology data in the Simons Simplex Collection. Our findings provide support for an alternative genomic classification of ASD subgroups using morphology data, which may inform intervention protocols.

  Study EGAS00001005753

• cfRRBS on cfDNA from pediatric cancer

  In the clinical management of pediatric solid tumors, histological examination of tumor tissue obtained by a biopsy remains the gold standard to establish a conclusive pathological diagnosis. The DNA methylation pattern of a tumor is known to correlate with the histopathological diagnosis across cancer types and is showing promise in the diagnostic workup of tumor samples. This methylation pattern can be detected in the cell-free DNA. Here, we provide proof-of-concept of histopathologic classification of pediatric tumors using cell-free reduced representation bisulfite sequencing (cf-RRBS) from retrospectively collected plasma and cerebrospinal fluid samples. We determined the correct tumor type in 49 out of 60 (81.6%) samples starting from minute amounts (less than 10 ng) of cell-free DNA. We demonstrate that the majority of misclassifications were associated with sample quality and not with the extent of disease. Our approach has the potential to help tackle some of the remaining diagnostic challenges in pediatric oncology in a cost-effective and minimally invasive manner.

  Study EGAS00001004194