Whole-Genome and Epigenomic Landscapes of Etiologically Distinct Subtypes of Cholangiocarcinoma
National University of Singapore1, Khon Kaen University2, Duke University3, Singapore General Hospital4, University of Tokyo5, Harvard University6, Chang Gung University7, Sun Yat-sen University8, Southern Medical University9, Federal University of São Paulo10, Yonsei University11, Los Alamos National Laboratory12
01 Oct 2017-Cancer Discovery (American Association for Cancer Research)-Vol. 7, Iss: 10, pp 1116-1135
TL;DR: In this paper, the authors analyzed 489 cholangiocarcinoma (CCA) from 10 countries, combining whole-genome (71 cases), targeted/exome, copy-number, gene expression, and DNA methylation information.
Abstract: Cholangiocarcinoma (CCA) is a hepatobiliary malignancy exhibiting high incidence in countries with endemic liver-fluke infection. We analyzed 489 CCAs from 10 countries, combining whole-genome (71 cases), targeted/exome, copy-number, gene expression, and DNA methylation information. Integrative clustering defined 4 CCA clusters-fluke-positive CCAs (clusters 1/2) are enriched in ERBB2 amplifications and TP53 mutations; conversely, fluke-negative CCAs (clusters 3/4) exhibit high copy-number alterations and PD-1/PD-L2 expression, or epigenetic mutations (IDH1/2, BAP1) and FGFR/PRKA-related gene rearrangements. Whole-genome analysis highlighted FGFR2 3' untranslated region deletion as a mechanism of FGFR2 upregulation. Integration of noncoding promoter mutations with protein-DNA binding profiles demonstrates pervasive modulation of H3K27me3-associated sites in CCA. Clusters 1 and 4 exhibit distinct DNA hypermethylation patterns targeting either CpG islands or shores-mutation signature and subclonality analysis suggests that these reflect different mutational pathways. Our results exemplify how genetics, epigenetics, and environmental carcinogens can interplay across different geographies to generate distinct molecular subtypes of cancer.Significance: Integrated whole-genome and epigenomic analysis of CCA on an international scale identifies new CCA driver genes, noncoding promoter mutations, and structural variants. CCA molecular landscapes differ radically by etiology, underscoring how distinct cancer subtypes in the same organ may arise through different extrinsic and intrinsic carcinogenic processes. Cancer Discov; 7(10); 1116-35. ©2017 AACR.This article is highlighted in the In This Issue feature, p. 1047.
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Carlos III Health Institute1, Ikerbasque2, University of the Basque Country3, University of Salamanca4, National Health Service5, University of Manchester6, Imperial College London7, Mayo Clinic8, Sapienza University of Rome9, University of Copenhagen10, University of Glasgow11, University of Regensburg12, Yale University13, University of Padua14, University of Edinburgh15, University of Minnesota16, Marche Polytechnic University17, University of Rennes18, University of Paris19, University of Florence20, University of Milano-Bicocca21, University of Zurich22, Erasmus University Rotterdam23, University of Barcelona24
TL;DR: This expert Consensus Statement, endorsed by the ENS-CCA, summarizes the latest advances in CCA, including classification, genetics and treatment, and provides recommendations for CCA management and priorities across basic, translational and clinical research.
Abstract: Cholangiocarcinoma (CCA) includes a cluster of highly heterogeneous biliary malignant tumours that can arise at any point of the biliary tree Their incidence is increasing globally, currently accounting for ~15% of all primary liver cancers and ~3% of gastrointestinal malignancies The silent presentation of these tumours combined with their highly aggressive nature and refractoriness to chemotherapy contribute to their alarming mortality, representing ~2% of all cancer-related deaths worldwide yearly The current diagnosis of CCA by non-invasive approaches is not accurate enough, and histological confirmation is necessary Furthermore, the high heterogeneity of CCAs at the genomic, epigenetic and molecular levels severely compromises the efficacy of the available therapies In the past decade, increasing efforts have been made to understand the complexity of these tumours and to develop new diagnostic tools and therapies that might help to improve patient outcomes In this expert Consensus Statement, which is endorsed by the European Network for the Study of Cholangiocarcinoma, we aim to summarize and critically discuss the latest advances in CCA, mostly focusing on classification, cells of origin, genetic and epigenetic abnormalities, molecular alterations, biomarker discovery and treatments Furthermore, the horizon of CCA for the next decade from 2020 onwards is highlighted
926 citations
University of Southampton1, University of Birmingham2, Clatterbridge Cancer Centre NHS Foundation Trust3, University of Liverpool4, University of Leeds5, University Hospitals Birmingham NHS Foundation Trust6, Leeds Teaching Hospitals NHS Trust7, Cambridge University Hospitals NHS Foundation Trust8, University of Bristol9, Weston Park Hospital10, University of Glasgow11, University College Hospital12, Heidelberg University13, University of Edinburgh14, University of Manchester15, University College London16
TL;DR: This randomised, controlled, multicentre, phase 3 study aimed to determine whether adjuvant capecitabine improved overall survival compared with observation following surgery for biliary tract cancer.
Abstract: BACKGROUND
Despite improvements in multidisciplinary management, patients with biliary tract cancer have a poor outcome. Only 20% of patients are eligible for surgical resection with curative intent, with 5-year overall survival of less than 10% for all patients. To our knowledge, no studies have described a benefit of adjuvant therapy. We aimed to determine whether adjuvant capecitabine improved overall survival compared with observation following surgery for biliary tract cancer.
METHODS
This randomised, controlled, multicentre, phase 3 study was done across 44 specialist hepatopancreatobiliary centres in the UK. Eligible patients were aged 18 years or older and had histologically confirmed cholangiocarcinoma or muscle-invasive gallbladder cancer who had undergone a macroscopically complete resection (which includes liver resection, pancreatic resection, or, less commonly, both) with curative intent, and an Eastern Cooperative Oncology Group performance status of less than 2. Patients who had not completely recovered from previous surgery or who had previous chemotherapy or radiotherapy for biliary tract cancer were also excluded. Patients were randomly assigned 1:1 to receive oral capecitabine (1250 mg/m twice daily on days 1-14 of a 21-day cycle, for eight cycles) or observation commencing within 16 weeks of surgery. Treatment was not masked, and allocation concealment was achieved with a computerised minimisation algorithm that stratified patients by surgical centre, site of disease, resection status, and performance status. The primary outcome was overall survival. As prespecified, analyses were done by intention to treat and per protocol. This study is registered with EudraCT, number 2005-003318-13.
FINDINGS
Between March 15, 2006, and Dec 4, 2014, 447 patients were enrolled; 223 patients with biliary tract cancer resected with curative intent were randomly assigned to the capecitabine group and 224 to the observation group. The data cutoff for this analysis was March 6, 2017. The median follow-up for all patients was 60 months (IQR 37-60). In the intention-to-treat analysis, median overall survival was 51·1 months (95% CI 34·6-59·1) in the capecitabine group compared with 36·4 months (29·7-44·5) in the observation group (adjusted hazard ratio [HR] 0·81, 95% CI 0·63-1·04; p=0·097). In a protocol-specified sensitivity analysis, adjusting for minimisation factors and nodal status, grade, and gender, the overall survival HR was 0·71 (95% CI 0·55-0·92; p=0·010). In the prespecified per-protocol analysis (210 patients in the capecitabine group and 220 in the observation group), median overall survival was 53 months (95% CI 40 to not reached) in the capecitabine group and 36 months (30-44) in the observation group (adjusted HR 0·75, 95% CI 0·58-0·97; p=0·028). In the intention-to-treat analysis, median recurrence-free survival was 24·4 months (95% CI 18·6-35·9) in the capecitabine group and 17·5 months (12·0-23·8) in the observation group. In the per-protocol analysis, median recurrence-free survival was 25·9 months (95% CI 19·8-46·3) in the capecitabine group and 17·4 months (12·0-23·7) in the observation group. Adverse events were measured in the capecitabine group only, and of the 213 patients who received at least one cycle, 94 (44%) had at least one grade 3 toxicity, the most frequent of which were hand-foot syndrome in 43 (20%) patients, diarrhoea in 16 (8%) patients, and fatigue in 16 (8%) patients. One (<1%) patient had grade 4 cardiac ischaemia or infarction. Serious adverse events were observed in 47 (21%) of 223 patients in the capecitabine group and 22 (10%) of 224 patients in the observation group. No deaths were deemed to be treatment related.
INTERPRETATION
Although this study did not meet its primary endpoint of improving overall survival in the intention-to-treat population, the prespecified sensitivity and per-protocol analyses suggest that capecitabine can improve overall survival in patients with resected biliary tract cancer when used as adjuvant chemotherapy following surgery and could be considered as standard of care. Furthermore, the safety profile is manageable, supporting the use of capecitabine in this setting.
FUNDING
Cancer Research UK and Roche.
652 citations
TL;DR: This work determined the single-cell transcriptomic landscape of liver cancer biospecimens from 19 patients and found a link between hypoxia-dependent vascular endothelial growth factor expression in tumor diversity and TME polarization.
365 citations
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TL;DR: In this article, the causes, diagnosis, molecular classification, and treatment of biliary tract cancer are discussed, including intrahepatic, perihilar, and distal cholangiocarcinoma as well as gallbladder cancer.
283 citations
TL;DR: The authors showed that the use of this drug remains widespread in Asia and particularly in Taiwan, and that it appears to increase the risk of multiple different cancer types, and proposed that additional measures aimed at primary prevention through avoidance of AA exposure and investigation of possible approaches to secondary prevention are warranted.
Abstract: Many traditional pharmacopeias include Aristolochia and related plants, which contain nephrotoxins and mutagens in the form of aristolochic acids and similar compounds (collectively, AA). AA is implicated in multiple cancer types, sometimes with very high mutational burdens, especially in upper tract urothelial cancers (UTUCs). AA-associated kidney failure and UTUCs are prevalent in Taiwan, but AA's role in hepatocellular carcinomas (HCCs) there remains unexplored. Therefore, we sequenced the whole exomes of 98 HCCs from two hospitals in Taiwan and found that 78% showed the distinctive mutational signature of AA exposure, accounting for most of the nonsilent mutations in known cancer driver genes. We then searched for the AA signature in 1400 HCCs from diverse geographic regions. Consistent with exposure through known herbal medicines, 47% of Chinese HCCs showed the signature, albeit with lower mutation loads than in Taiwan. In addition, 29% of HCCs from Southeast Asia showed the signature. The AA signature was also detected in 13 and 2.7% of HCCs from Korea and Japan as well as in 4.8 and 1.7% of HCCs from North America and Europe, respectively, excluding one U.S. hospital where 22% of 87 "Asian" HCCs had the signature. Thus, AA exposure is geographically widespread. Asia, especially Taiwan, appears to be much more extensively affected, which is consistent with other evidence of patterns of AA exposure. We propose that additional measures aimed at primary prevention through avoidance of AA exposure and investigation of possible approaches to secondary prevention are warranted.
268 citations
References
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TL;DR: SAMtools as discussed by the authors implements various utilities for post-processing alignments in the SAM format, such as indexing, variant caller and alignment viewer, and thus provides universal tools for processing read alignments.
Abstract: Summary: The Sequence Alignment/Map (SAM) format is a generic alignment format for storing read alignments against reference sequences, supporting short and long reads (up to 128 Mbp) produced by different sequencing platforms. It is flexible in style, compact in size, efficient in random access and is the format in which alignments from the 1000 Genomes Project are released. SAMtools implements various utilities for post-processing alignments in the SAM format, such as indexing, variant caller and alignment viewer, and thus provides universal tools for processing read alignments.
Availability: http://samtools.sourceforge.net
Contact: [email protected]
45,957 citations
"Whole-Genome and Epigenomic Landsca..." refers methods in this paper
...We removed PCR duplicates using SAMTools (55) and performed indel realignments using Genome Analysis Toolkit v1....
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TL;DR: Burrows-Wheeler Alignment tool (BWA) is implemented, a new read alignment package that is based on backward search with Burrows–Wheeler Transform (BWT), to efficiently align short sequencing reads against a large reference sequence such as the human genome, allowing mismatches and gaps.
Abstract: Motivation: The enormous amount of short reads generated by the new DNA sequencing technologies call for the development of fast and accurate read alignment programs. A first generation of hash table-based methods has been developed, including MAQ, which is accurate, feature rich and fast enough to align short reads from a single individual. However, MAQ does not support gapped alignment for single-end reads, which makes it unsuitable for alignment of longer reads where indels may occur frequently. The speed of MAQ is also a concern when the alignment is scaled up to the resequencing of hundreds of individuals.
Results: We implemented Burrows-Wheeler Alignment tool (BWA), a new read alignment package that is based on backward search with Burrows–Wheeler Transform (BWT), to efficiently align short sequencing reads against a large reference sequence such as the human genome, allowing mismatches and gaps. BWA supports both base space reads, e.g. from Illumina sequencing machines, and color space reads from AB SOLiD machines. Evaluations on both simulated and real data suggest that BWA is ~10–20× faster than MAQ, while achieving similar accuracy. In addition, BWA outputs alignment in the new standard SAM (Sequence Alignment/Map) format. Variant calling and other downstream analyses after the alignment can be achieved with the open source SAMtools software package.
Availability: http://maq.sourceforge.net
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43,862 citations
TL;DR: The Gene Set Enrichment Analysis (GSEA) method as discussed by the authors focuses on gene sets, that is, groups of genes that share common biological function, chromosomal location, or regulation.
Abstract: Although genomewide RNA expression analysis has become a routine tool in biomedical research, extracting biological insight from such information remains a major challenge. Here, we describe a powerful analytical method called Gene Set Enrichment Analysis (GSEA) for interpreting gene expression data. The method derives its power by focusing on gene sets, that is, groups of genes that share common biological function, chromosomal location, or regulation. We demonstrate how GSEA yields insights into several cancer-related data sets, including leukemia and lung cancer. Notably, where single-gene analysis finds little similarity between two independent studies of patient survival in lung cancer, GSEA reveals many biological pathways in common. The GSEA method is embodied in a freely available software package, together with an initial database of 1,325 biologically defined gene sets.
34,830 citations
TL;DR: The GATK programming framework enables developers and analysts to quickly and easily write efficient and robust NGS tools, many of which have already been incorporated into large-scale sequencing projects like the 1000 Genomes Project and The Cancer Genome Atlas.
Abstract: Next-generation DNA sequencing (NGS) projects, such as the 1000 Genomes Project, are already revolutionizing our understanding of genetic variation among individuals. However, the massive data sets generated by NGS—the 1000 Genome pilot alone includes nearly five terabases—make writing feature-rich, efficient, and robust analysis tools difficult for even computationally sophisticated individuals. Indeed, many professionals are limited in the scope and the ease with which they can answer scientific questions by the complexity of accessing and manipulating the data produced by these machines. Here, we discuss our Genome Analysis Toolkit (GATK), a structured programming framework designed to ease the development of efficient and robust analysis tools for next-generation DNA sequencers using the functional programming philosophy of MapReduce. The GATK provides a small but rich set of data access patterns that encompass the majority of analysis tool needs. Separating specific analysis calculations from common data management infrastructure enables us to optimize the GATK framework for correctness, stability, and CPU and memory efficiency and to enable distributed and shared memory parallelization. We highlight the capabilities of the GATK by describing the implementation and application of robust, scale-tolerant tools like coverage calculators and single nucleotide polymorphism (SNP) calling. We conclude that the GATK programming framework enables developers and analysts to quickly and easily write efficient and robust NGS tools, many of which have already been incorporated into large-scale sequencing projects like the 1000 Genomes Project and The Cancer Genome Atlas.
20,557 citations
TL;DR: This paper proposed parametric and non-parametric empirical Bayes frameworks for adjusting data for batch effects that is robust to outliers in small sample sizes and performs comparable to existing methods for large samples.
Abstract: SUMMARY Non-biological experimental variation or “batch effects” are commonly observed across multiple batches of microarray experiments, often rendering the task of combining data from these batches difficult. The ability to combine microarray data sets is advantageous to researchers to increase statistical power to detect biological phenomena from studies where logistical considerations restrict sample size or in studies that require the sequential hybridization of arrays. In general, it is inappropriate to combine data sets without adjusting for batch effects. Methods have been proposed to filter batch effects from data, but these are often complicated and require large batch sizes (>25) to implement. Because the majority of microarray studies are conducted using much smaller sample sizes, existing methods are not sufficient. We propose parametric and non-parametric empirical Bayes frameworks for adjusting data for batch effects that is robust to outliers in small sample sizes and performs comparable to existing methods for large samples. We illustrate our methods using two example data sets and show that our methods are justifiable, easy to apply, and useful in practice. Software for our method is freely available at: http://biosun1.harvard.edu/complab/batch/.
6,319 citations
Additional excerpts
...Batch effects were removed using ComBat (70)....
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