Haplotype-specific assembly of shattered chromosomes in esophageal adenocarcinomas

The epigenetic landscape of cancer is regulated by many factors, but primarily it derives from the underlying genome sequence. Chromothripsis is a catastrophic localized genome shattering event that drives, and often initiates, cancer evolution. We characterized five esophageal adenocarcinoma organoids with chromothripsis using long-read sequencing and transcriptome and epigenome profiling. Complex structural variation and subclonal variants meant that haplotype-aware de novo methods were required to generate contiguous cancer genome assemblies. Chromosomes were assembled separately and scaffolded using haplotype-resolved Hi-C reads, producing accurate assemblies even with up to 900 structural rearrangements. There were widespread differences between the chromothriptic and wild-type copies of chromosomes in topologically associated domains, chromatin accessibility, histone modifications, and gene expression. Differential epigenome peaks were most enriched within 10 kb of chromothriptic structural variants. Alterations in transcriptome and higher-order chromosome organization frequently occurred near differential epigenetic marks. Overall, chromothripsis reshapes gene regulation, causing coordinated changes in epigenetic landscape, transcription, and chromosome conformation.

Diagnostic utility of whole genome sequencing in adults with B-other acute lymphoblastic leukemia

Genomic profiling during the diagnosis of B-cell precursor acute lymphoblastic leukemia (BCP-ALL) in adults is used to guide disease classification, risk stratification, and treatment decisions. Patients for whom diagnostic screening fails to identify disease-defining or risk-stratifying lesions are classified as having B-other ALL. We screened a cohort of 652 BCP-ALL cases enrolled in UKALL14 to identify and perform whole genome sequencing (WGS) of paired tumor-normal samples. For 52 patients with B-other, we compared the WGS findings with data from clinical and research cytogenetics. WGS identified a cancer-associated event in 51 of 52 patients, including an established subtype defining genetic alterations that were previously missed with standard-of-care (SoC) genetics in 5 of them. Of the 47 true B-other ALL, we identified a recurrent driver in 87% (41). A complex karyotype via cytogenetics emerges as a heterogeneous group, including distinct genetic alterations associated with either favorable (DUX4-r) or poor outcomes (MEF2D-r and IGK::BCL2). For a subset of 31 cases, we integrated the findings from RNA sequencing (RNA-seq) analysis to include fusion gene detection and classification based on gene expression. Compared with RNA-seq, WGS was sufficient to detect and resolve recurrent genetic subtypes; however, RNA-seq can provide orthogonal validation of findings. In conclusion, we demonstrated that WGS can identify clinically relevant genetic abnormalities missed with SoC testing as well as identify leukemia driver events in virtually all cases of B-other ALL.

Serum testosterone and prostate cancer in men with germline BRCA1/2 pathogenic variants

Objectives

The relation of serum androgens and the development of prostate cancer (PCa) is subject of debate. Lower total testosterone (TT) levels have been associated with increased PCa detection and worse pathological features after treatment. However, data from the Reduction by Dutasteride of Prostate Cancer Events (REDUCE) and Prostate Cancer Prevention (PCPT) trial groups indicate no association. The aim of this study is to investigate the association of serum androgen levels and PCa detection in a prospective screening study of men at higher genetic risk of aggressive PCa due to BRCA1/2 pathogenic variants (PVs), the IMPACT study.

Methods

Men enrolled in the IMPACT study provided serum samples during regular visits. Hormonal levels were calculated using immunoassays. Free testosterone (FT) was calculated from TT and sex hormone binding globulin (SHBG) using the Sodergard mass equation. Age, body mass index (BMI), prostate-specific antigen (PSA) and hormonal concentrations were compared between genetic cohorts. We also explored associations between age and TT, SHBG, FT and PCa, in the whole subset and stratified by BRCA1/2 PVs status.

Results

A total of 777 participants in the IMPACT study had TT and SHBG measurements in serum samples at annual visits, giving 3940 prospective androgen levels, from 266 BRCA1 PVs carriers, 313 BRCA2 PVs carriers and 198 non-carriers. The median number of visits per patient was 5. There was no difference in TT, SHBG and FT between carriers and non-carriers. In a univariate analysis, androgen levels were not associated with PCa. In the analysis stratified by carrier status, no significant association was found between hormonal levels and PCa in non-carriers, BRCA1 or BRCA2 PVs carriers.

Conclusions

Male BRCA1/2 PVs carriers have a similar androgen profile to non-carriers. Hormonal levels were not associated with PCa in men with and without BRCA1/2 PVs. Mechanisms related to the particularly aggressive phenotype of PCa in BRCA2 PVs carriers may therefore not be linked with circulating hormonal levels.

Genetic and genomic analysis of acute lymphoblastic leukemia in older adults reveals a distinct profile of abnormalities: analysis of 210 patients from the UKALL14 and UKALL60+ clinical trials

Despite being predominantly a childhood disease, the incidence of acute lymphoblastic leukemia (ALL) has a second peak in adults aged 60 years and over. These older adults fare extremely poorly with existing treatment strategies and very few studies have undertaken a comprehensive genetic and genomic characterization to improve prognosis in this age group. We performed cytogenetic, single nucleotide polymorphism (SNP) array and next-generation sequencing (NGS) analyses on samples from 210 patients aged ≥60 years from the UKALL14 and UKALL60+ clinical trials. BCR-ABL1-positive disease was present in 26% (55/210) of patients, followed by low hypodiploidy/near triploidy in 13% (28/210). Cytogenetically cryptic rearrangements in CRLF2, ZNF384 and MEF2D were detected in 5%, 1% and <1% of patients, respectively. Copy number abnormalities were common and deletions in ALL driver genes were seen in 77% of cases. IKZF1 deletion was present in 51% (40/78) of samples tested and the IKZF1plus profile was identified in over a third (28/77) of cases of B-cell precursor ALL. The genetic good-risk abnormalities high hyperdiploidy (n=2), ETV6-RUNX1 (no cases) and ERG deletion (no cases) were exceptionally rare in this cohort. RAS pathway mutations were seen in 17% (4/23) of screened samples. KDM6A abnormalities, including biallelic deletions, were discovered in 5% (4/78) of SNP arrays and 9% (2/23) of NGS samples, and represent novel, potentially therapeutically actionable lesions using EZH2 inhibitors. Outcome remained poor with 5-year event-free and overall survival rates of 17% and 24%, respectively, across the cohort, indicating a need for novel therapeutic strategies.

Clonal diversification and histogenesis of malignant germ cell tumours

Germ cell tumours (GCTs) are a collection of benign and malignant neoplasms derived from primordial germ cells. They are uniquely able to recapitulate embryonic and extraembryonic tissues, which carries prognostic and therapeutic significance. The developmental pathways underpinning GCT initiation and histogenesis are incompletely understood. Here, we study the relationship of histogenesis and clonal diversification in GCTs by analysing the genomes and transcriptomes of 547 microdissected histological units. We find no correlation between genomic and histological heterogeneity. However, we identify unifying features including the retention of fetal developmental transcripts across tissues, expression changes on chromosome 12p, and a conserved somatic evolutionary sequence of whole genome duplication followed by clonal diversification. While this pattern is preserved across all GCTs, the developmental timing of the duplication varies between prepubertal and postpubertal cases. In addition, tumours of younger children exhibit distinct substitution signatures which may lend themselves as potential biomarkers for risk stratification. Our findings portray the extensive diversification of GCT tissues and genetic subclones as randomly distributed, while identifying overarching transcriptional and genomic features.

Unified classification and risk-stratification in Acute Myeloid Leukemia

Clinical recommendations for Acute Myeloid Leukemia (AML) classification and risk-stratification remain heavily reliant on cytogenetic findings at diagnosis, which are present in <50% of patients. Using comprehensive molecular profiling data from 3,653 patients we characterize and validate 16 molecular classes describing 100% of AML patients. Each class represents diverse biological AML subgroups, and is associated with distinct clinical presentation, likelihood of response to induction chemotherapy, risk of relapse and death over time. Secondary AML-2, emerges as the second largest class (24%), associates with high-risk disease, poor prognosis irrespective of flow Minimal Residual Disease (MRD) negativity, and derives significant benefit from transplantation. Guided by class membership we derive a 3-tier risk-stratification score that re-stratifies 26% of patients as compared to standard of care. This results in a unified framework for disease classification and risk-stratification in AML that relies on information from cytogenetics and 32 genes. Last, we develop an open-access patient-tailored clinical decision support tool.

Diverse mutational landscapes in human lymphocytes

The lymphocyte genome is prone to many threats, including programmed mutation during differentiation1, antigen-driven proliferation and residency in diverse microenvironments. Here, after developing protocols for expansion of single-cell lymphocyte cultures, we sequenced whole genomes from 717 normal naive and memory B and T cells and haematopoietic stem cells. All lymphocyte subsets carried more point mutations and structural variants than haematopoietic stem cells, with higher burdens in memory cells than in naive cells, and with T cells accumulating mutations at a higher rate throughout life. Off-target effects of immunological diversification accounted for approximately half of the additional differentiation-associated mutations in lymphocytes. Memory B cells acquired, on average, 18 off-target mutations genome-wide for every on-target IGHV mutation during the germinal centre reaction. Structural variation was 16-fold higher in lymphocytes than in stem cells, with around 15% of deletions being attributable to off-target recombinase-activating gene activity. DNA damage from ultraviolet light exposure and other sporadic mutational processes generated hundreds to thousands of mutations in some memory cells. The mutation burden and signatures of normal B cells were broadly similar to those seen in many B-cell cancers, suggesting that malignant transformation of lymphocytes arises from the same mutational processes that are active across normal ontogeny. The mutational landscape of normal lymphocytes chronicles the off-target effects of programmed genome engineering during immunological diversification and the consequences of differentiation, proliferation and residency in diverse microenvironments.

Abstract 226: Recurrent trisomies, variable selection and precancerous evolution in the normal gastric epithelium

Gastric cancer is the third leading cause of cancer-related mortality globally and is often associated with infectious agents such as the bacterium Helicobacter pylori. However, the background mutational landscape in normal gastric epithelium and the first genomic steps towards the formation of gastric cancer remain poorly understood. Here, we use whole-genome sequencing of microdissected gastric glands (n=271) from 30 patients, 18 of whom had gastric cancer. We show that gastric glands are clonal structures and accrue approximately 27 single base substitutions per year. While the mutational signatures in most normal glands reflect age-related mutagenesis, gastric glands sampled close to a tumor showed exposure to a mutagenic process enriched in tumors (COSMIC reference mutational signature SBS17). Phylogenetic analysis shows that acquisition of SBS17 substitutions is closely linked to overt malignant transformation. We also observe widespread trisomies of specific chromosomes, which are recurrently and independently acquired in many gastric glands of the same patient. Mutations in genes encoding epigenetic modifiers and chromatin remodelers showed evidence of positive selection and were highly enriched in some patients. This was confirmed by targeted sequencing of cancer genes in a further 1008 gastric glands. Strikingly, glands that exhibit driver mutations, a recurrent trisomy or elevated mutation loads only overlap minimally, suggesting a highly variable and patient-specific mutation and selection landscape in the normal gastric epithelium. Taken together, these results give novel insights into the preclinical evolution of gastric malignancies.

Citation Format: Tim H. Coorens, Grace Collord, Hyungchul Jung, Yichen Wang, Sonia Zumalave, Daniel Leongamornlert, Luiza Moore, Krishnaa Mahbubani, Kourosh Saeb-Parsy, Suet Yi Leung, Michael R. Stratton. Recurrent trisomies, variable selection and precancerous evolution in the normal gastric epithelium [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 226.

Prognostic impact of chromosomal abnormalities and copy number alterations in adult B-cell precursor acute lymphoblastic leukaemia: a UKALL14 study

Chromosomal abnormalities are established prognostic markers in adult ALL. We assessed the prognostic impact of established chromosomal abnormalities and key copy number alterations (CNA) among 652 patients with B-cell precursor ALL treated on a modern MRD driven protocol. Patients with KMT2A-AFF1, complex karyotype (CK) and low hypodiploidy/near-triploidy (HoTr) had high relapse rates 50%, 60% & 53% and correspondingly poor survival. Patients with BCR-ABL1 had an outcome similar to other patients. JAK-STAT abnormalities (CRLF2, JAK2) occurred in 6% patients and were associated with a high relapse rate (56%). Patients with ABL-class fusions were rare (1%). A small group of patients with ZNF384 fusions (n = 12) had very good survival. CNA affecting IKZF1, CDKN2A/B, PAX5, BTG1, ETV6, EBF1, RB1 and PAR1 were assessed in 436 patients. None of the individual deletions or profiles were associated with survival, either in the cohort overall or within key subgroups. Collectively these data indicate that primary genetic abnormalities are stronger prognostic markers than secondary deletions. We propose a revised UKALL genetic risk classification based on key established chromosomal abnormalities: (1) very high risk: CK, HoTr or JAK-STAT abnormalities; (2) high risk: KMT2A fusions; (3) Tyrosine kinase activating: BCR-ABL1 and ABL-class fusions; (4) standard risk: all other patients.

CDKN2A deletion is a frequent event associated with poor outcome in patients with peripheral T-cell lymphoma not otherwise specified (PTCL-NOS)

Nodal peripheral T-cell lymphoma not otherwise specified (PTCL-NOS) remains a diagnosis encompassing a heterogenous group of PTCL cases not fitting criteria for more homogeneous subtypes. They are characterized by a poor clinical outcome when treated with anthracycline-containing regimens. A better understanding of their biology could improve prognostic stratification and foster the development of novel therapeutic approaches. Recent targeted and whole exome sequencing studies have shown recurrent copy number abnormalities (CNAs) with prognostic significance. Here, investigating 5 formalin-fixed, paraffin embedded cases of PTCL-NOS by whole genome sequencing (WGS), we found a high prevalence of structural variants and complex events, such as chromothripsis likely responsible for the observed CNAs. Among them, CDKN2A and PTEN deletions emerged as the most frequent aberration, as confirmed in a final cohort of 143 patients with nodal PTCL. The incidence of CDKN2A and PTEN deletions among PTCL-NOS was 46% and 26%, respectively. Furthermore, we found that co-occurrence of CDKN2A and PTEN deletions is an event associated with PTCL-NOS with absolute specificity. In contrast, these deletions were rare and never co-occurred in angioimmunoblastic and anaplastic lymphomas. CDKN2A deletion was associated with shorter overall survival in multivariate analysis corrected by age, IPI, transplant eligibility and GATA3 expression (adjusted HR =2.53; 95% CI 1.006-6.3; p=0.048). These data suggest that CDKN2A deletions may be relevant for refining the prognosis of PTCL-NOS and their significance should be evaluated in prospective trials.

Convergent somatic mutations in metabolism genes in chronic liver disease

The progression of chronic liver disease to hepatocellular carcinoma is caused by the acquisition of somatic mutations that affect 20-30 cancer genes1-8. Burdens of somatic mutations are higher and clonal expansions larger in chronic liver disease9-13 than in normal liver13-16, which enables positive selection to shape the genomic landscape9-13. Here we analysed somatic mutations from 1,590 genomes across 34 liver samples, including healthy controls, alcohol-related liver disease and non-alcoholic fatty liver disease. Seven of the 29 patients with liver disease had mutations in FOXO1, the major transcription factor in insulin signalling. These mutations affected a single hotspot within the gene, impairing the insulin-mediated nuclear export of FOXO1. Notably, six of the seven patients with FOXO1S22W hotspot mutations showed convergent evolution, with variants acquired independently by up to nine distinct hepatocyte clones per patient. CIDEB, which regulates lipid droplet metabolism in hepatocytes17-19, and GPAM, which produces storage triacylglycerol from free fatty acids20,21, also had a significant excess of mutations. We again observed frequent convergent evolution: up to fourteen independent clones per patient with CIDEB mutations and up to seven clones per patient with GPAM mutations. Mutations in metabolism genes were distributed across multiple anatomical segments of the liver, increased clone size and were seen in both alcohol-related liver disease and non-alcoholic fatty liver disease, but rarely in hepatocellular carcinoma. Master regulators of metabolic pathways are a frequent target of convergent somatic mutation in alcohol-related and non-alcoholic fatty liver disease.

IKZF1 alterations are not associated with outcome in 498 adults with B-precursor ALL enrolled in the UKALL14 trial

IKZF1 deletions (ΔIKZF1) are commonly detected in B-precursor acute lymphoblastic leukemia (ALL; B-ALL) and are widely assumed to have a significant impact on outcome. We compared the ability of multiplex ligand-dependent probe amplification (MLPA) and polymerase chain reaction (PCR) to detect ΔIKZF1 and to determine the impact on event-free survival of patients with precursor B-ALL aged 23 to 65 years recruited to the completed trial UKALL14 (ISRCTN 66541317). From 655 recruits with BCR-ABL1+ and BCR-ABL1- B-ALL, all available diagnostic DNA samples (76% of the recruited population) were screened by multiplex end point PCR covering 4 deletions: dominant-negative (DN) Δ4-7 or the loss of function Δ2-7, Δ4-8, and Δ2-8 (n = 498), MLPA (n = 436), or by both (n = 420). Although patients with BCR-ABL1- ΔIKZF1 were more likely to have minimal residual disease at the end of induction, we did not find any impact of ΔIKZF1 (including subgroup analysis for DN or loss-of-function lesions) or the IKZF1plus genotype on event-free, overall survival, or relapse risk by univariable or multivariable analyses. Consistent with the technical approach, MLPA not only detected a wider range of deletions than PCR but also failed to detect some PCR-detected lesions. The main difference between our study and others reporting an association between ΔIKZF1 and outcome is the older age of participants in our population. The impact of ΔIKZF1 in ALL may be less marked in an older population of patients. Our study underscores the need for analyses in large, harmonized data sets. This trial was registered at www.clinicaltrials.gov as #NCT01085617.

The mutational landscape of human somatic and germline cells

Over the course of an individual's lifetime, normal human cells accumulate mutations1. Here we compare the mutational landscape in 29 cell types from the soma and germline using multiple samples from the same individuals. Two ubiquitous mutational signatures, SBS1 and SBS5/40, accounted for the majority of acquired mutations in most cell types, but their absolute and relative contributions varied substantially. SBS18, which potentially reflects oxidative damage2, and several additional signatures attributed to exogenous and endogenous exposures contributed mutations to subsets of cell types. The rate of mutation was lowest in spermatogonia, the stem cells from which sperm are generated and from which most genetic variation in the human population is thought to originate. This was due to low rates of ubiquitous mutational processes and may be partially attributable to a low rate of cell division in basal spermatogonia. These results highlight similarities and differences in the maintenance of the germline and soma.

Clinical utility of whole genome sequencing in hematological neoplasms

7028

Background: Hematological neoplasms are often characterized by acute onset and rapid disease progression. Cytogenetics, FISH, SNP arrays, targeted DNA and RNA sequencing are performed to inform diagnosis, risk stratification and guide treatment decisions. Whole genome sequencing (WGS) offers the opportunity to comprehensively characterize all putative biomarkers in a single assay. However, a limitation in current WGS implementation is the requirement for a germline sample, as sources of control tissue are frequently contaminated with leukemic cells resulting in false negative calls. Methods: To evaluate the clinical utility and feasibility of WGS in the diagnostic work up of leukemias, we analyzed 57 B-cell acute lymphoblastic leukemia (B-ALL) from the UKALL14 trial (NCT01085617) with no informative biomarkers at diagnosis. WGS analysis was performed on the leukemic sample and a matching control sample (with minimal residual disease level of <1%). Using this dataset, we trained the development of an unmatched (uWGS) analytical workflow (Isabl) for a tumor only WGS study. This workflow was validated across 20 hematologic neoplasms (12 B-ALL, 6 AML and 2 T-ALL). Results: Among the 57 cases, 5 failed QC owing to low tumor content (<25%). Of the remaining 52, putative biomarkers of clinical relevance were identified by WGS in 69% (36/52). These included delineation of aberrant karyotypes where conventional chromosome banding failed (4/52), the detection of newly described fusion genes (such as IGH-DUX4 and EP300-ZNF384 in 21/52) and recurrent gene mutations (i.e. PAX5 P80R, ZEB2 H1038R in 11/52). uWGS workflow in our training dataset captured 86% of biomarkers identified in the matched analysis (3/3 ploidy, 21/22 fusion and 7/11 coding). Concordance between the matched and uWGS workflow for arm-level and focal copy number alterations (CNAs), structural variants (SVs) and annotated hotspot mutations were 94%, 84%, 83% and 100% respectively. Independent validation of the uWGS workflow across 20 myeloid and lymphoid neoplasms, recapitulated all clinically reported biomarkers (14/15 CNAs, 16/16 SVs) as well as captured two novel findings not previously detected in two B-ALL patients, to include a focal deletion in BTG1 and the fusion gene P2RY8-CRLF2, as well as a NOTCH1 translocation in T-ALL. Conclusions: Our findings demonstrate that comprehensive WGS allows for the detection of the same biomarkers as a range of clinical assays using a single test, as well as the opportunity to discover novel clinical and research findings to support future correlative research and biomarker development. Additionally, we developed and validated an uWGS workflow that allows WGS analysis of hematopoietic neoplasms at diagnosis, enabling detection and reporting of clinically relevant biomarkers.

Revealing the impact of structural variants in multiple myeloma

The landscape of structural variants (SVs) in multiple myeloma remains poorly understood. Here, we performed comprehensive analysis of SVs in a large cohort of 752 multiple myeloma patients by low coverage long-insert whole genome sequencing. We identified 68 SV hotspots involving 17 new candidate driver genes, including the therapeutic targets BCMA (TNFRSF17), SLAMF and MCL1. Catastrophic complex rearrangements termed chromothripsis were present in 24% of patients and independently associated with poor clinical outcomes. Templated insertions were the second most frequent complex event (19%), mostly involved in super-enhancer hijacking and activation of oncogenes such as CCND1 and MYC. Importantly, in 31% of patients two or more seemingly independent putative driver events were caused by a single structural event, demonstrating that the complex genomic landscape of multiple myeloma can be acquired through few key events during tumor evolutionary history. Overall, this study reveals the critical role of SVs in multiple myeloma pathogenesis.

Timing the initiation of multiple myeloma

The evolution and progression of multiple myeloma and its precursors over time is poorly understood. Here, we investigate the landscape and timing of mutational processes shaping multiple myeloma evolution in a large cohort of 89 whole genomes and 973 exomes. We identify eight processes, including a mutational signature caused by exposure to melphalan. Reconstructing the chronological activity of each mutational signature, we estimate that the initial transformation of a germinal center B-cell usually occurred during the first 2nd-3rd decades of life. We define four main patterns of activation-induced deaminase (AID) and apolipoprotein B mRNA editing catalytic polypeptide-like (APOBEC) mutagenesis over time, including a subset of patients with evidence of prolonged AID activity during the pre-malignant phase, indicating antigen-responsiveness and germinal center reentry. Our findings provide a framework to study the etiology of multiple myeloma and explore strategies for prevention and early detection.

The mutational landscape of normal human endometrial epithelium

All normal somatic cells are thought to acquire mutations, but understanding of the rates, patterns, causes and consequences of somatic mutations in normal cells is limited. The uterine endometrium adopts multiple physiological states over a lifetime and is lined by a gland-forming epithelium1,2. Here, using whole-genome sequencing, we show that normal human endometrial glands are clonal cell populations with total mutation burdens that increase at about 29 base substitutions per year and that are many-fold lower than those of endometrial cancers. Normal endometrial glands frequently carry 'driver' mutations in cancer genes, the burden of which increases with age and decreases with parity. Cell clones with drivers often originate during the first decades of life and subsequently progressively colonize the epithelial lining of the endometrium. Our results show that mutational landscapes differ markedly between normal tissues-perhaps shaped by differences in their structure and physiology-and indicate that the procession of neoplastic change that leads to endometrial cancer is initiated early in life.

Type 1 Interferon Responses Underlie Tumor-Selective Replication of Oncolytic Measles Virus

The mechanism of tumor-selective replication of oncolytic measles virus (MV) is poorly understood. Using a stepwise model of cellular transformation, in which oncogenic hits were additively expressed in human bone marrow-derived mesenchymal stromal cells, we show that MV-induced oncolysis increased progressively with transformation. The type 1 interferon (IFN) response to MV infection was significantly reduced and delayed, in accordance with the level of transformation. Consistently, we observed delayed and reduced signal transducer and activator of transcription (STAT1) phosphorylation in the fully transformed cells. Pre-treatment with IFNβ restored resistance to MV-mediated oncolysis. Gene expression profiling to identify the genetic correlates of susceptibility to MV oncolysis revealed a dampened basal level of immune-related genes in the fully transformed cells compared to their normal counterparts. IFN-induced transmembrane protein 1 (IFITM1) was the foremost basally downregulated immune gene. Stable IFITM1 overexpression in MV-susceptible cells resulted in a 50% increase in cell viability and a significant reduction in viral replication at 24 h after MV infection. Overall, our data indicate that the basal reduction in functions of the type 1 IFN pathway is a major contributor to the oncolytic selectivity of MV. In particular, we have identified IFITM1 as a restriction factor for oncolytic MV, acting at early stages of infection.

Genomic landscape and chronological reconstruction of driver events in multiple myeloma

The multiple myeloma (MM) genome is heterogeneous and evolves through preclinical and post-diagnosis phases. Here we report a catalog and hierarchy of driver lesions using sequences from 67 MM genomes serially collected from 30 patients together with public exome datasets. Bayesian clustering defines at least 7 genomic subgroups with distinct sets of co-operating events. Focusing on whole genome sequencing data, complex structural events emerge as major drivers, including chromothripsis and a novel replication-based mechanism of templated insertions, which typically occur early. Hyperdiploidy also occurs early, with individual trisomies often acquired in different chronological windows during evolution, and with a preferred order of acquisition. Conversely, positively selected point mutations, whole genome duplication and chromoplexy events occur in later disease phases. Thus, initiating driver events, drawn from a limited repertoire of structural and numerical chromosomal changes, shape preferred trajectories of evolution that are biologically relevant but heterogeneous across patients.

Author Correction: A practical guide for mutational signature analysis in hematological malignancies

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A practical guide for mutational signature analysis in hematological malignancies

Analysis of mutational signatures is becoming routine in cancer genomics, with implications for pathogenesis, classification, prognosis, and even treatment decisions. However, the field lacks a consensus on analysis and result interpretation. Using whole-genome sequencing of multiple myeloma (MM), chronic lymphocytic leukemia (CLL) and acute myeloid leukemia, we compare the performance of public signature analysis tools. We describe caveats and pitfalls of de novo signature extraction and fitting approaches, reporting on common inaccuracies: erroneous signature assignment, identification of localized hyper-mutational processes, overcalling of signatures. We provide reproducible solutions to solve these issues and use orthogonal approaches to validate our results. We show how a comprehensive mutational signature analysis may provide relevant biological insights, reporting evidence of c-AID activity among unmutated CLL cases or the absence of BRCA1/BRCA2-mediated homologous recombination deficiency in a MM cohort. Finally, we propose a general analysis framework to ensure production of accurate and reproducible mutational signature data.

Abstract 970: The mutational landscape of normal human endometrial epithelium

Human endometrium is a highly dynamic tissue that undergoes hundreds of cycles of breakdown, rapid repair and remodelling in response to the oscillating levels of oestrogen and progesterone during female reproductive years. The marked regenerative capacity of this tissue’s epithelial compartment is maintained by intra-glandular adult stem cells (ASCs) that reside within the stratum basalis which is retained during menstruation. Although the endometrial ASCs were first described over a decade ago, they remain poorly characterised in comparison to their counterparts in other tissues, such as the small and the large intestines. In particular, the size of the stem cell pool within individual glands, the rates of their division, and mutational landscape are largely unknown. In this study, we isolated 215 morphologically normal endometrial glands from women aged 19 to 81 using laser capture microscopy. Analysis of whole-genome sequencing data identified that the overwhelming majority of the glands were clonal cell populations, and thus originating from a single ASC. Somatic mutations were found to accumulate at a linear rate during adult life. Elevated body mass index (BMI), a well-recognised risk factor for endometrial cancer, accelerated the rate of mutation acquisition. Surprisingly, despite the heterogeneity in age, reproductive history and BMI in our cohort, we find relatively homogenous mutational processes within normal endometrium. Comparison with cancer, shows lower somatic mutation burden and fewer operative signatures. Remarkably, we not only identify recurrent acquisitions of certain cancer-associated mutations, particularly those that are advantageous to cell growth, proliferation and migration, but also show that such events occur early in life, potentially even before adolescence. Over time, these mutant ASCs serve as a reservoir for the acquisition of further driver mutations to the extent that in some cases, the entire sampled endometrium becomes ‘neoplastic’ on the genomic level while still retaining the apparently normal phenotype. In older individuals, we observe a shift in the spectrum of acquired cancer-associated mutations, possibly reflecting post-menopausal changes in the levels of sex-steroid hormones and the resultant tissue microenvironment.

Citation Format: Luiza Moore, Daniel Leongamornlert, Tim Coorens, Mathijs Sanders, Peter Ellis, Francesco Maura, Kevin Dawson, Simon F. Brunner, Jyoti Nangalia, Henry Lee-Six, Raheleh Rahbari, Patrick Tarpey, Yvette Hooks, Krishnaa Mahbubani, Christine A. Iacobuzio-Donahue, Jan J. Brosens, Inigo Martincorena, Kourosh Saeb-Parsy, Peter J. Campbell, Michael R. Stratton. The mutational landscape of normal human endometrial epithelium [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 970.

Integration of transcriptional and mutational data simplifies the stratification of peripheral T-cell lymphoma

The histological diagnosis of peripheral T-cell lymphoma (PTCL) can represent a challenge, particularly in the case of closely related entities such as angioimmunoblastic T-lymphoma (AITL), PTCL-not otherwise specified (PTCL-NOS), and ALK-negative anaplastic large-cell lymphoma (ALCL). Although gene expression profiling and next generations sequencing have been proven to define specific features recurrently associated with distinct entities, genomic-based stratifications have not yet led to definitive diagnostic criteria and/or entered into the routine clinical practice. Herein, to improve the current molecular classification between AITL and PTCL-NOS, we analyzed the transcriptional profiles from 503 PTCLs stratified according to their molecular configuration and integrated them with genomic data of recurrently mutated genes (RHOA ^G17V , TET2, IDH2 ^R172 , and DNMT3A) in 53 cases (39 AITLs and 14 PTCL-NOSs) included in the series. Our analysis unraveled that the mutational status of RHOA ^G17V , TET2, and DNMT3A poorly correlated, individually, with peculiar transcriptional fingerprints. Conversely, in IDH2 ^R172 samples a strong transcriptional signature was identified that could act as a surrogate for mutational status. The integrated analysis of clinical, mutational, and molecular data led to a simplified 19-gene signature that retains high accuracy in differentiating the main nodal PTCL entities. The expression levels of those genes were confirmed in an independent cohort profiled by RNA-sequencing.

Author Correction: Association analyses of more than 140,000 men identify 63 new prostate cancer susceptibility loci

In the version of this article initially published, the name of author Manuela Gago-Dominguez was misspelled as Manuela Gago Dominguez. The error has been corrected in the HTML and PDF version of the article.

Association analyses of more than 140,000 men identify 63 new prostate cancer susceptibility loci

Genome-wide association studies (GWAS) and fine-mapping efforts to date have identified more than 100 prostate cancer (PrCa)-susceptibility loci. We meta-analyzed genotype data from a custom high-density array of 46,939 PrCa cases and 27,910 controls of European ancestry with previously genotyped data of 32,255 PrCa cases and 33,202 controls of European ancestry. Our analysis identified 62 novel loci associated (P < 5.0 × 10-8) with PrCa and one locus significantly associated with early-onset PrCa (≤55 years). Our findings include missense variants rs1800057 (odds ratio (OR) = 1.16; P = 8.2 × 10-9; G>C, p.Pro1054Arg) in ATM and rs2066827 (OR = 1.06; P = 2.3 × 10-9; T>G, p.Val109Gly) in CDKN1B. The combination of all loci captured 28.4% of the PrCa familial relative risk, and a polygenic risk score conferred an elevated PrCa risk for men in the ninetieth to ninety-ninth percentiles (relative risk = 2.69; 95% confidence interval (CI): 2.55-2.82) and first percentile (relative risk = 5.71; 95% CI: 5.04-6.48) risk stratum compared with the population average. These findings improve risk prediction, enhance fine-mapping, and provide insight into the underlying biology of PrCa1.

Abstract 1225: Rare variants in DNA damage repair genes are associated with male breast cancer predisposition

Male breast cancer accounts for approximately 1% of all breast cancers diagnosed each year in the UK. Germline mutations in DNA damage response genes are known to be associated with many forms of cancer, including breast cancer. In order to identify low frequency male breast cancer predisposition genes, we performed targeted resequencing of more than 300 genes that were selected on the basis of involvement in DNA maintenance and repair pathways. Using a cost-effective protocol based on an automated library preparation method and a multiplexed hybridization enrichment step, we sequenced 1,029 male breast cancer cases from the UK Breast Cancer Now male breast cancer study (MBCS) and 1,254 controls from the MBCS and the ICR1000 UK exome series. Rare variants localising to 19 genes were significantly associated with risk of male breast cancer. Genes with an excess of rare coding mutations included the known breast cancer susceptibility genes BRCA2, CHEK2 and ATM as well as multiple members of the Fanconi anaemia (FA) pathway. Loss of heterozygosity (LOH) affecting the wildtype allele of putative predisposition genes was observed more than 10% of cases with matched tumor samples. In addition to LOH in BRCA2 mutation carries, somatic losses were observed that affected CCNE1, ATM, PALB2, BARD1, CHEK2, POLL and RAD9A. These data represent the largest analysis of rare variants in male breast cancer to date and have enabled the identification of known and putative novel susceptibility genes.

Citation Format: Sarah L. Maguire, Katarzyna Tomczyk, Eleni Perrakis, Edward Saunders, Daniel Leongamornlert, ZSofia Kote-Jarai, Rosalind Eeles, Montserrat Garcia-Closas, Paul Pharoah, Douglas Easton, Christopher J. Lord, Alan Ashworth, Anthony Swerdlow, Nick Orr. Rare variants in DNA damage repair genes are associated with male breast cancer predisposition [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 1225.

Sequencing of prostate cancers identifies new cancer genes, routes of progression and drug targets

Prostate cancer represents a substantial clinical challenge because it is difficult to predict outcome and advanced disease is often fatal. We sequenced the whole genomes of 112 primary and metastatic prostate cancer samples. From joint analysis of these cancers with those from previous studies (930 cancers in total), we found evidence for 22 previously unidentified putative driver genes harboring coding mutations, as well as evidence for NEAT1 and FOXA1 acting as drivers through noncoding mutations. Through the temporal dissection of aberrations, we identified driver mutations specifically associated with steps in the progression of prostate cancer, establishing, for example, loss of CHD1 and BRCA2 as early events in cancer development of ETS fusion-negative cancers. Computational chemogenomic (canSAR) analysis of prostate cancer mutations identified 11 targets of approved drugs, 7 targets of investigational drugs, and 62 targets of compounds that may be active and should be considered candidates for future clinical trials.

DNA repair gene panel mutations in young onset prostate cancer cases in the

18

Background: Prostate cancer (PrCa) is the most common solid tumour in men in the Western world. There is substantial evidence that PrCa predisposition is due both to common and rare germline variation. Methods: We screened 167 genes from DNA damage response and repair pathways, within a UK based cohort of young onset cases (diagnosed at < 65 years) and controls. Samples were sequenced using a custom Agilent SureSelectXT bait library and Illumina HiSeq technology and processed using a BWA/GATK 2.8 pipeline. Following sample QC, data were analysed from 1,285 PrCa cases and 1,163 controls. Results: We identified 5,086 single nucleotide variants (SNVs) and 175 indels; 233 unique protein truncating variants (PTVs) with MAF < 0.5% in controls were found in 97 genes of the screening panel. The total proportion of PTV carriers in cases was higher than in controls (14.5% vs. 11.6%, P = 0.036; OR = 1.29, 95% CI 1.01-1.64). This enrichment was greater within the previously reported BROCA gene set of 22 tumour suppressor genes (4.5% vs 2.2%, P = 2.5x10-3; OR = 2.07, 95% CI 1.28-3.34). To identify genes which best to distinguish PrCa cases from controls, we applied the adaptive combination of P values algorithm, ADA, for genes with at least 2 carriers of PTVs. This analysis selected 10 genes, (OR = 3.37, 95% CI 2.05-5.66, PADA= 5.99x10-3); men with PTVs in these were about 3.4-fold more likely to have PrCa (5.8% vs. 1.8%). We subsequently compared aggressive cases (Gleason score ≥ 8, n = 204) with non-aggressive cases (Gleason score ≤ 7, n = 1049) and lethal PrCa cases (cause of death PrCa, n = 183) with indolent cases (Gleason score ≤ 6, n = 563) to evaluate genes associated with poor clinical prognosis. Using ADA, 4 genes were selected for aggressive PrCa ( PADA= 0.006) and 2 of these also for lethal PrCa ( PADA= 0.057). Conclusions: These gene sets provide an 11 gene panel which could be used for clinical testing and will help to facilitate the development of a PrCa specific sequencing panel with both predictive and prognostic potential.

Genome-wide association of familial prostate cancer cases identifies evidence for a rare segregating haplotype at 8q24.21

Previous genome-wide association studies (GWAS) of prostate cancer risk focused on cases unselected for family history and have reported over 100 significant associations. The International Consortium for Prostate Cancer Genetics (ICPCG) has now performed a GWAS of 2511 (unrelated) familial prostate cancer cases and 1382 unaffected controls from 12 member sites. All samples were genotyped on the Illumina 5M+exome single nucleotide polymorphism (SNP) platform. The GWAS identified a significant evidence for association for SNPs in six regions previously associated with prostate cancer in population-based cohorts, including 3q26.2, 6q25.3, 8q24.21, 10q11.23, 11q13.3, and 17q12. Of note, SNP rs138042437 (p = 1.7e(-8)) at 8q24.21 achieved a large estimated effect size in this cohort (odds ratio = 13.3). 116 previously sampled affected relatives of 62 risk-allele carriers from the GWAS cohort were genotyped for this SNP, identifying 78 additional affected carriers in 62 pedigrees. A test for an excess number of affected carriers among relatives exhibited strong evidence for co-segregation of the variant with disease (p = 8.5e(-11)). The majority (92 %) of risk-allele carriers at rs138042437 had a consistent estimated haplotype spanning approximately 100 kb of 8q24.21 that contained the minor alleles of three rare SNPs (dosage minor allele frequencies <1.7 %), rs183373024 (PRNCR1), previously associated SNP rs188140481, and rs138042437 (CASC19). Strong evidence for co-segregation of a SNP on the haplotype further characterizes the haplotype as a prostate cancer predisposition locus.

High burden of copy number alterations and c-MYC amplification in prostate cancer from BRCA2 germline mutation carriers

BACKGROUND

Germline BRCA2 mutations are associated with poorer outcome prostate cancer (PCa) compared with sporadic tumours but this association remains to be characterised. In this study, we aim to assess if there is a signature set of copy number alterations (CNA) that could aid to the identification of BRCA2-mutated tumours and would assist us to understand their aggressive clinical behaviour.

METHODS

High-resolution array comparative genomic hybridisation profiling of DNA from PCa and matched morphologically normal prostate samples from 9 BRCA2 germline mutation carriers and 16 non-carriers in combination with unsupervised analysis was used to define copy number features.

RESULTS

PCa from BRCA2 germline mutation carriers (B2T) harbour significantly more CNA than non-carrier tumours (NCTs) (P = 14 × 10(-6)). A hundred and sixteen regions had a significantly different distribution with both false discovery rate (FDR) and P value <0.01, including CNA in the genomic region containing c-MYC that was present in 89% B2T versus 12.5% NCT (P = 3 × 10(-4)). Loss of heterozygosity (LOH) at the BRCA2 locus was observed in 67% of B2T. Elevated CNA are already present in 50% of the morphologically normal prostate tissue from BRCA2 carriers.

CONCLUSION

The relative high amount of CNAs in morphologically normal prostate tissue of BRCA2 carriers implies a field effect and together with the observed LOH could be used as a marker of PCa risk in these men. Several features previously associated with poor PCa outcome have been found to be significantly more common in BRCA2-mutated PCa than in sporadic tumours and may help to explain their adverse prognosis and be of relevance for targeted therapies.

Multiple novel prostate cancer susceptibility signals identified by fine-mapping of known risk loci among Europeans

Genome-wide association studies (GWAS) have identified numerous common prostate cancer (PrCa) susceptibility loci. We have fine-mapped 64 GWAS regions known at the conclusion of the iCOGS study using large-scale genotyping and imputation in 25 723 PrCa cases and 26 274 controls of European ancestry. We detected evidence for multiple independent signals at 16 regions, 12 of which contained additional newly identified significant associations. A single signal comprising a spectrum of correlated variation was observed at 39 regions; 35 of which are now described by a novel more significantly associated lead SNP, while the originally reported variant remained as the lead SNP only in 4 regions. We also confirmed two association signals in Europeans that had been previously reported only in East-Asian GWAS. Based on statistical evidence and linkage disequilibrium (LD) structure, we have curated and narrowed down the list of the most likely candidate causal variants for each region. Functional annotation using data from ENCODE filtered for PrCa cell lines and eQTL analysis demonstrated significant enrichment for overlap with bio-features within this set. By incorporating the novel risk variants identified here alongside the refined data for existing association signals, we estimate that these loci now explain ∼38.9% of the familial relative risk of PrCa, an 8.9% improvement over the previously reported GWAS tag SNPs. This suggests that a significant fraction of the heritability of PrCa may have been hidden during the discovery phase of GWAS, in particular due to the presence of multiple independent signals within the same region.

Abstract 4606: Fine mapping of 64 prostate cancer GWAS regions identifies multiple novel association signals

Genome-wide association studies (GWAS) have identified 100 common prostate cancer (PrCa) susceptibility loci to date. We performed comprehensive fine-mapping of 64 GWAS regions using genotyping and imputation to a 1000 Genomes reference panel for 25,779 PrCa cases and 26,218 controls of European ancestry from the PRACTICAL Consortium and two UK GWAS studies. In order to identify independent variants associated to PrCa, SNPs significant at P ≤10-4 were included in a stepwise logistic regression (SLR). Where the initial SLR identified multiple independent SNPs in a region, we re-analysed the region conditioning on the top hit. The adjusted results were subsequently trimmed using a P-value cut-off of ≤10-5 and a second SLR performed to identify independently significant index SNPs. We observed a single independent signal at 39 regions, with a novel, more significantly associated index SNP at 35 of these. Amongst these, we confirmed association in the European population for 2 loci previously reported in Asian GWAS. At 16 regions there was evidence for multiple independent signals, 14 of these contain newly identified additional significant associations. Functional annotation using data from ENCODE filtered for PrCa cell lines showed enrichment for overlap with bio-features within the fine-mapped SNP set and eQTL analysis identified novel candidate genes regulated by SNPs discovered in this study. Furthermore, we observed a 7% (from 32%-to 39%) improvement in the estimated proportion of familial relative risk explained through these refined and newly identified genetic variants. This study demonstrates the utility of fine-mapping, in silico functional annotation and eQTL approaches to narrow down the number of candidate functional variants. In addition, since a greater proportion of GWAS loci contained multiple independent risk variants than previously appreciated; this may explain a proportion of the missing heritability of complex diseases.

Citation Format: Zsofia Kote-Jarai, Ali Amin Al Olama, Tokhir Dadaev, Dennis Hazelett, Qiuyan Li, Daniel Leongamornlert, Ed Saunders, Matthew Feedman, David Conti, Douglas Easton, Gerhard Coetzee, Rosalind Eeles, The PRACTICAL Consortium. Fine mapping of 64 prostate cancer GWAS regions identifies multiple novel association signals. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4606. doi:10.1158/1538-7445.AM2015-4606

Effect of BRCA Mutations on Metastatic Relapse and Cause-specific Survival After Radical Treatment for Localised Prostate Cancer

BACKGROUND

Germline BRCA mutations are associated with worse prostate cancer (PCa) outcomes; however, the most appropriate management for mutation carriers has not yet been investigated.

OBJECTIVE

To evaluate the response of BRCA carriers to conventional treatments for localised PCa by analysing metastasis-free survival (MFS) and cause-specific survival (CSS) following radical prostatectomy (RP) or external-beam radiation therapy (RT).

DESIGN, SETTING, AND PARTICIPANTS

Tumour features and outcomes of 1302 patients with local/locally advanced PCa (including 67 BRCA mutation carriers) were analysed. RP was undergone by 535 patients (35 BRCA); 767 received RT (32 BRCA). Median follow-up was 64 mo.

OUTCOME MEASUREMENTS AND STATISTICAL ANALYSIS

Median survival and 3-, 5-, and 10-yr survival rates were estimated using the Kaplan-Meier method. Generated survival curves were compared using the log-rank test. Cox regression analyses were used to assess the prognostic value of BRCA mutations.

RESULTS AND LIMITATIONS

A total of 67 BRCA carriers and 1235 noncarriers were included. At 3, 5, and 10 yr after treatment, 97%, 94%, and 84% of noncarriers and 90%, 72%, and 50% of carriers were free from metastasis (p<0.001). The 3-, 5- and 10-yr CSS rates were significantly better in the noncarrier cohort (99%, 97%, and 85%, respectively) than in carriers (96%, 76%, and 61%, respectively; p<0.001). Multivariate analysis confirmed BRCA mutations as an independent prognostic factor for MFS (hazard ratio [HR]: 2.36; 95% confidence interval [CI], 1.38-4.03; p=0.002) and CSS (HR: 2.17; 95% CI, 1.16-4.07; p=0.016).

CONCLUSIONS

BRCA carriers had worse outcomes than noncarriers when conventionally treated for local/locally advanced PCa.

PATIENT SUMMARY

Prostate cancer patients with germline BRCA mutations had worse outcomes than noncarriers when conventionally treated with surgery or radiation therapy.

Risk Analysis of Prostate Cancer in PRACTICAL, a Multinational Consortium, Using 25 Known Prostate Cancer Susceptibility Loci

BACKGROUND

Genome-wide association studies have identified multiple genetic variants associated with prostate cancer risk which explain a substantial proportion of familial relative risk. These variants can be used to stratify individuals by their risk of prostate cancer.

METHODS

We genotyped 25 prostate cancer susceptibility loci in 40,414 individuals and derived a polygenic risk score (PRS). We estimated empirical odds ratios (OR) for prostate cancer associated with different risk strata defined by PRS and derived age-specific absolute risks of developing prostate cancer by PRS stratum and family history.

RESULTS

The prostate cancer risk for men in the top 1% of the PRS distribution was 30.6 (95% CI, 16.4-57.3) fold compared with men in the bottom 1%, and 4.2 (95% CI, 3.2-5.5) fold compared with the median risk. The absolute risk of prostate cancer by age of 85 years was 65.8% for a man with family history in the top 1% of the PRS distribution, compared with 3.7% for a man in the bottom 1%. The PRS was only weakly correlated with serum PSA level (correlation = 0.09).

CONCLUSIONS

Risk profiling can identify men at substantially increased or reduced risk of prostate cancer. The effect size, measured by OR per unit PRS, was higher in men at younger ages and in men with family history of prostate cancer. Incorporating additional newly identified loci into a PRS should improve the predictive value of risk profiles.

IMPACT

We demonstrate that the risk profiling based on SNPs can identify men at substantially increased or reduced risk that could have useful implications for targeted prevention and screening programs.

Analysis of the genetic phylogeny of multifocal prostate cancer identifies multiple independent clonal expansions in neoplastic and morphologically normal prostate tissue

Genome-wide DNA sequencing was used to decrypt the phylogeny of multiple samples from distinct areas of cancer and morphologically normal tissue taken from the prostates of three men. Mutations were present at high levels in morphologically normal tissue distant from the cancer, reflecting clonal expansions, and the underlying mutational processes at work in morphologically normal tissue were also at work in cancer. Our observations demonstrate the existence of ongoing abnormal mutational processes, consistent with field effects, underlying carcinogenesis. This mechanism gives rise to extensive branching evolution and cancer clone mixing, as exemplified by the coexistence of multiple cancer lineages harboring distinct ERG fusions within a single cancer nodule. Subsets of mutations were shared either by morphologically normal and malignant tissues or between different ERG lineages, indicating earlier or separate clonal cell expansions. Our observations inform on the origin of multifocal disease and have implications for prostate cancer therapy in individual cases.

Prostate-specific antigen velocity as a predictive biomarker in a prospective prostate cancer screening study (IMPACT study)

16

Background: We retrospectively assessed the clinical application of Prostate Specific Antigen Velocity (PSA V) in the IMPACT study (Identification of Men with a genetic predisposition to ProstAte Cancer: Targeted screening in men at higher genetic risk and controls). This is a case-control prostate cancer (PrCa) screening study for men with a known genetic predisposition to PrCa; participants with a single PSA reading above 3ng/ml are offered diagnostic TRUS prostate biopsies (PB). Methods: We calculated PSA velocity (PSA V) using all three validated methods, including the arithmetic mean, the linear regression and the first and last readings equations. Pearson chi-square test was used to compare PSA V between four genetic groups: BRCA1 carriers and BRCA1 negative controls and BRCA2 carriers and BRCA2 negative controls. Results: PSA V data were evaluated in 191 men who underwent a PB with a total of 57 PrCas diagnosed. PSA V using both a threshold of 0ng/ml/year and 0.75ng/ml/year in any of the three methods was not predictive of PrCa diagnosis in BRCA1/2 controls and BRCA1 carriers. Conversely, BRCA2 carriers with a PSA V over 0.75ng/ml/year (by linear regression) were 5 times more likely to be diagnosed with PrCa [95%CI=1.5-14; p=0.003]. Interestingly PSA V using linear regression was predictive of clinically significant tumours as defined by Gleason Score (GS) >= 7. Regardless of their genetic status, men with a PSA V over 0.75/ng/ml/year were 3 times more likely to have a clinically significant PrCa [95% CI: 1.006-11.107; p=0.045] whereas men with a BRCA2 mutation were 12 times more likely [95%CI: 1.1-98; p=0.039]. Conclusions: PSA V is an important tool for identifying which men with a BRCA2 mutation would benefit from a prostatic biopsy and could be incorporated into a predictive model, along with the total PSA value. PSA V also predicts for tumour aggressiveness regardless of genetic predisposition, but more so for those with a known high risk gene mutation. Clinical trial information: NCT00261456.

Abstract 5065: Fine-mapping the HOXB region detects common variants tagging a rare coding allele: Evidence for synthetic association in prostate cancer

The HOXB13 gene has been implicated in prostate cancer susceptibility. We performed a high resolution fine-mapping analysis to comprehensively evaluate the association between common genetic variation across the HOXB genetic locus at 17q21 and PrCa risk. This involved genotyping 700 SNPs using a custom Illumina iSelect array (iCOGS) followed by imputation of 3195 SNPs in 20,440 prostate cancer cases and 21,469 controls in The PRACTICAL consortium. We identified a cluster of highly correlated common variants situated within or closely upstream of HOXB13 that were significantly associated with prostate cancer risk, described by rs117576373, OR 1.30, P = 2.62×10-14. Additional genotyping, conditional regression and haplotype analyses indicated that the newly identified common variants tag a rare, partially correlated coding variant in the HOXB13 gene, G84E, rs138213197, which has been identified recently as a moderate penetrance prostate cancer susceptibility allele. The potential for GWAS associations detected through common SNPs to be driven by rare causal variants with higher relative risks has long been proposed; however, to our knowledge this is the first experimental evidence for this phenomenon of synthetic association contributing to cancer susceptibility.

Citation Format: Zsofia Kote-Jarai, Edward Saunders, Tokhir Dadaev, Daniel Leongamornlert, Sarah Jugurnauth-Little, Malgorzata Tymrakiewicz, Koveela Govindasami, Fredrik Wiklund, Ali Amin Al Olama, Sara Benlloch, The PRACTICAL Consortium, Douglas Easton, Keneth Muir, Rosalind Eeles. Fine-mapping the HOXB region detects common variants tagging a rare coding allele: Evidence for synthetic association in prostate cancer. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 5065. doi:10.1158/1538-7445.AM2014-5065

A meta-analysis of 87,040 individuals identifies 23 new susceptibility loci for prostate cancer

Genome-wide association studies (GWAS) have identified 76 variants associated with prostate cancer risk predominantly in populations of European ancestry. To identify additional susceptibility loci for this common cancer, we conducted a meta-analysis of > 10 million SNPs in 43,303 prostate cancer cases and 43,737 controls from studies in populations of European, African, Japanese and Latino ancestry. Twenty-three new susceptibility loci were identified at association P < 5 × 10(-8); 15 variants were identified among men of European ancestry, 7 were identified in multi-ancestry analyses and 1 was associated with early-onset prostate cancer. These 23 variants, in combination with known prostate cancer risk variants, explain 33% of the familial risk for this disease in European-ancestry populations. These findings provide new regions for investigation into the pathogenesis of prostate cancer and demonstrate the usefulness of combining ancestrally diverse populations to discover risk loci for disease.

Frequent germline deleterious mutations in DNA repair genes in familial prostate cancer cases are associated with advanced disease

BACKGROUND

Prostate cancer (PrCa) is one of the most common diseases to affect men worldwide and among the leading causes of cancer-related death. The purpose of this study was to use second-generation sequencing technology to assess the frequency of deleterious mutations in 22 tumour suppressor genes in familial PrCa and estimate the relative risk of PrCa if these genes are mutated.

METHODS

Germline DNA samples from 191 men with 3 or more cases of PrCa in their family were sequenced for 22 tumour suppressor genes using Agilent target enrichment and Illumina technology. Analysis for genetic variation was carried out by using a pipeline consisting of BWA, Genome Analysis Toolkit (GATK) and ANNOVAR. Clinical features were correlated with mutation status using standard statistical tests. Modified segregation analysis was used to determine the relative risk of PrCa conferred by the putative loss-of-function (LoF) mutations identified.

RESULTS

We discovered 14 putative LoF mutations in 191 samples (7.3%) and these mutations were more frequently associated with nodal involvement, metastasis or T4 tumour stage (P=0.00164). Segregation analysis of probands with European ancestry estimated that LoF mutations in any of the studied genes confer a relative risk of PrCa of 1.94 (95% CI: 1.56-2.42).

CONCLUSIONS

These findings show that LoF mutations in DNA repair pathway genes predispose to familial PrCa and advanced disease and therefore warrants further investigation. The clinical utility of these findings will become increasingly important as targeted screening and therapies become more widespread.

Telomere length shows no association with BRCA1 and BRCA2 mutation status

This study aimed to determine whether telomere length (TL) is a marker of cancer risk or genetic status amongst two cohorts of BRCA1 and BRCA2 mutation carriers and controls. The first group was a prospective set of 665 male BRCA1/2 mutation carriers and controls (mean age 53 years), all healthy at time of enrollment and blood donation, 21 of whom have developed prostate cancer whilst on study. The second group consisted of 283 female BRCA1/2 mutation carriers and controls (mean age 48 years), half of whom had been diagnosed with breast cancer prior to enrollment. TL was quantified by qPCR from DNA extracted from peripheral blood lymphocytes. Weighted and unweighted Cox regressions and linear regression analyses were used to assess whether TL was associated with BRCA1/2 mutation status or cancer risk. We found no evidence for association between developing cancer or being a BRCA1 or BRCA2 mutation carrier and telomere length. It is the first study investigating TL in a cohort of genetically predisposed males and although TL and BRCA status was previously studied in females our results don't support the previous finding of association between hereditary breast cancer and shorter TL.

Translating genetic risk factors for prostate cancer to the clinic: 2013 and beyond

Prostate cancer (PrCa) is the most commonly diagnosed cancer in the male UK population, with over 40,000 new cases per year. PrCa has a complex, polygenic predisposition, due to rare variants such as BRCA and common variants such as single nucleotide polymorphisms (SNPs). With the introduction of genome-wide association studies, 78 susceptibility loci (SNPs) associated with PrCa risk have been identified. Genetic profiling could risk-stratify a population, leading to the discovery of a higher proportion of clinically significant disease and a reduction in the morbidity related to age-based prostate-specific antigen screening. Based on the combined risk of the 78 SNPs identified so far, the top 1% of the risk distribution has a 4.7-times higher risk of developing PrCa compared with the average of the general population.

Clinical implications of a prostate cancer risk SNP profile in two treatment cohorts

e16000

Background: Prostate cancer (PCa) has a heritable risk and genome-wide association studies (GWAS) have so far identified 76 single nucleotide polymorphisms (SNPs) associated with PCa risk. Currently these SNPs have only been evaluated against overall PCa risk and several disease parameters. Their clinical utility remains undefined. We explore the potential prognostic role of the risk SNP profile in 2 PCa cohorts; Active Surveillance (AS) and androgen deprivation therapy (ADT). Methods: PCa patients at the Royal Marsden Hospital who consented for DNA analyses were eligible. 2 separate cohorts were identified; those undergoing AS and those receiving ADT. The risk SNPs were genotyped using Sequenom or Fluidigm platforms. The cumulative SNP risk scores for each patient were calculated by summing risk alleles for each loci using the weighted effect as estimated in previous studies (log-additive model). For the AS group, the risk scores were analysed against defined adverse outcomes in AS, including adverse histology on repeat biopsy and time to treatment, to determine their prognostic value. For the ADT group, the risk scores were assessed against time to relapse, defined by either biochemical relapse or evidence of progression on imaging. Results: In the AS group, 391 patients’ DNA were studied. 31% of those have since undergone treatment and 30% have histological upgrade on repeat biopsies. On univariate analysis, there was no significant relationship between the risk scores and biopsy upgrade or time to treatment (p>0.05). When analysing differences in outcomes between the higher and lower risk groups (top 25% and lowest 25% of the genetic risk distribution), there was again no relationship (p>0.05). In the ADT group, 567 patients’ DNA were studied. The mean duration of response was 30 months. No significant associations were found when risk scores were analysed as a continuous variable against time to relapse on ADT, or when analysing difference between the top and bottom 25% of the risk distribution (p>0.05). Conclusions: PCa SNP risk scores have not been shown to be prognostic factors in either AS or ADT. This is the first study analysing the potential prognostic role of the latest GWAS risk SNPs in PCa treatment cohorts.

Germline BRCA mutations are associated with higher risk of nodal involvement, distant metastasis, and poor survival outcomes in prostate cancer

PURPOSE

To analyze the baseline clinicopathologic characteristics of prostate tumors with germline BRCA1 and BRCA2 (BRCA1/2) mutations and the prognostic value of those mutations on prostate cancer (PCa) outcomes.

PATIENTS AND METHODS

This study analyzed the tumor features and outcomes of 2,019 patients with PCa (18 BRCA1 carriers, 61 BRCA2 carriers, and 1,940 noncarriers). The Kaplan-Meier method and Cox regression analysis were used to evaluate the associations between BRCA1/2 status and other PCa prognostic factors with overall survival (OS), cause-specific OS (CSS), CSS in localized PCa (CSS_M0), metastasis-free survival (MFS), and CSS from metastasis (CSS_M1).

RESULTS

PCa with germline BRCA1/2 mutations were more frequently associated with Gleason ≥ 8 (P = .00003), T3/T4 stage (P = .003), nodal involvement (P = .00005), and metastases at diagnosis (P = .005) than PCa in noncarriers. CSS was significantly longer in noncarriers than in carriers (15.7 v 8.6 years, multivariable analyses [MVA] P = .015; hazard ratio [HR] = 1.8). For localized PCa, 5-year CSS and MFS were significantly higher in noncarriers (96% v 82%; MVA P = .01; HR = 2.6%; and 93% v 77%; MVA P = .009; HR = 2.7, respectively). Subgroup analyses confirmed the poor outcomes in BRCA2 patients, whereas the role of BRCA1 was not well defined due to the limited size and follow-up in this subgroup.

CONCLUSION

Our results confirm that BRCA1/2 mutations confer a more aggressive PCa phenotype with a higher probability of nodal involvement and distant metastasis. BRCA mutations are associated with poor survival outcomes and this should be considered for tailoring clinical management of these patients.

Abstract 2546: Fine-mapping identifies multiple prostate cancer risk loci at 5p15, one of which associates with TERT expression

We have previously reported an association between prostate cancer (PrCa) risk and rs2242652 on 5p15. rs2242652 lies in intron 4 of TERT, which encodes telomerase reverse transcriptase, the catalytic subunit of the telomerase ribonucleoprotein complex. Telomerase catalyzes the de novo addition of telomere repeat sequences on to chromosome ends and thereby counterbalances telomere-dependent replicative senescence. Associations between SNPs in the TERT region and multiple cancer types have been reported; however no correlation has been observed thus far between the cancer-associated SNPs in TERT and gene expression or telomere length. To comprehensively evaluate the association between genetic variation across this region and PrCa we performed a fine-mapping analysis by direct genotyping using either a custom Illumina iSelect array (114 SNPs on iCOGS) or Sequenom MassArray iPlex (25 SNPs) followed by imputation of 1,094 SNPs in 22,301 PrCa cases and 22,320 controls in the PRACTICAL consortium. To determine independently associated variants in this region, we performed multiple stepwise logistic regression analysis; SNPs were included in the model if they were significant at P&lt;10−4 after adjustment for other SNPs. Regression models identified multiple independent associations, reflecting the complexity of this region. These SNPs fall into four regions consisting of clusters of highly or moderately correlated variants, and there is only weak LD between SNPs in different regions. To investigate whether SNPs in any of these regions were associated with TERT gene expression, we performed qPCR assays on RNA from benign prostate tissue samples using the Fluidigm Biomark™ HD system. We found evidence that the risk reducing alleles of several variants in region one associated with elevated TERT expression, providing a plausible mechanism for the differential effect of SNPs on PrCa risk. Deep re-sequencing of these loci may help to further refine this region and facilitate selection of prospective causal variants for functional validation studies.

Citation Format: Zsofia Kote-Jarai, Edward Saunders, Daniel Leongamornlert, Malgorzata Tymrakiewicz, Tokhir Dadaev, Sarah Jugurnauth, Sara Benlloch, Ali Amin Al Olama, Helen Ross-Adams, David Neal, The UKGPCS Collaborators and The PRACTICAL Consortium, Douglas Easton, Rosalind Eeles. Fine-mapping identifies multiple prostate cancer risk loci at 5p15, one of which associates with TERT expression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2546. doi:10.1158/1538-7445.AM2013-2546

Effect of germ-line BRCA mutations in biochemical relapse and survival after treatment for localized prostate cancer

29

Background: Biochemical relapse after local treatment for prostate cancer (PCa) indicates recurrent disease and is associated with shorter cause-specific survival (CSS). Germline BRCA mutations are associated with worse PrCa outcomes. In this study, we analyzed biochemical-progression free survival (bPFS) after conventional treatments for localized PCa in a cohort of BRCA patients from the UK. Currently, BRCA1/2 carriers are treated with the same protocols used for non-carriers. Methods: In this retrospective case-control study, each BRCA carrier (10 BRCA1 and 34 BRCA2) treated with radical prostatectomy (RP) or external beam radiotherapy (RT) was matched with 3 non-carriers (NC) by: age at diagnosis (±5 yrs), TNM stage, Gleason score, presenting PSA, local treatment (RT or RP), androgen-deprivation therapy (ADT) and year of treatment (±5yrs). All NC were screened for BRCA1 and BRCA2 mutations. Biochemical failure was reviewed according to ASTRO and NCCN criteria. The Kaplan-Meier method and a multivariate Cox regression model adjusted by matching factors were employed. Results: 176 patients (pts) were included. Median follow-up was 97 months (ms). Median age at diagnosis was 58.5 yrs (43-75). 80 pts received RT (16 BRCA2, 4 BRCA1, 60 NC) and 85% also received ADT≥6 ms. 96pts underwent RP (18 BRCA2, 6 BRCA1 and 72 NC). Following RT treatment, 5yrs-CSS was 96% in NC and 47% in BRCA carriers (p=2x10-5), whilst no difference was seen after RP (5yrs-CSS was 98.5% in NC vs 93.3% in BRCA). Five-years bFPFS after RT was 74% in NC and 24% in BRCA (p=0.002). No difference was observed in 5yrs-bPFS between BRCA carriers and NC treated with RP (52% vs 66% , p=0.346). The adjusted MVA (including tumour stage, local treatment, ADT and BRCA status) confirmed the independent prognostic value of BRCA status for bPFS and CSS. Among BRCA carriers, the independent risk was greater when the analysis was limited to BRCA2 pts . Conclusions: Our results suggest that BRCA carriers have worse local disease control than NC when conventionally treated with RT. No differences in bPFS were observed in pts treated with RP after >8 yrs median follow-up. These results may have implications for tailoring clinical management in these patients.