Publications by authors named "John V Pearson"

84 Publications

Patient-derived xenograft models capture genomic heterogeneity in endometrial cancer.

Genome Med 2022 Jan 10;14(1). Epub 2022 Jan 10.

School of Biomedical Sciences, Queensland University of Technology located at the Translational Research Institute, Brisbane, QLD, Australia.

Background: Endometrial cancer (EC) is a major gynecological cancer with increasing incidence. It comprises four molecular subtypes with differing etiology, prognoses, and responses to chemotherapy. In the future, clinical trials testing new single agents or combination therapies will be targeted to the molecular subtype most likely to respond. As pre-clinical models that faithfully represent the molecular subtypes of EC are urgently needed, we sought to develop and characterize a panel of novel EC patient-derived xenograft (PDX) models.

Methods: Here, we report whole exome or whole genome sequencing of 11 PDX models and their matched primary tumor. Analysis of multiple PDX lineages and passages was performed to study tumor heterogeneity across lineages and/or passages. Based on recent reports of frequent defects in the homologous recombination (HR) pathway in EC, we assessed mutational signatures and HR deficiency scores and correlated these with in vivo responses to the PARP inhibitor (PARPi) talazoparib in six PDXs representing the copy number high/p53-mutant and mismatch-repair deficient molecular subtypes of EC.

Results: PDX models were successfully generated from grade 2/3 tumors, including three uterine carcinosarcomas. The models showed similar histomorphology to the primary tumors and represented all four molecular subtypes of EC, including five mismatch-repair deficient models. The different PDX lineages showed a wide range of inter-tumor and intra-tumor heterogeneity. However, for most PDX models, one arm recapitulated the molecular landscape of the primary tumor without major genomic drift. An in vivo response to talazoparib was detected in four copy number high models. Two models (carcinosarcomas) showed a response consistent with stable disease and two models (one copy number high serous EC and another carcinosarcoma) showed significant tumor growth inhibition, albeit one consistent with progressive disease; however, all lacked the HR deficiency genomic signature.

Conclusions: EC PDX models represent the four molecular subtypes of disease and can capture intra-tumor heterogeneity of the original primary tumor. PDXs of the copy number high molecular subtype showed sensitivity to PARPi; however, deeper and more durable responses will likely require combination of PARPi with other agents.
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http://dx.doi.org/10.1186/s13073-021-00990-zDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8751371PMC
January 2022

Multiomic profiling of checkpoint inhibitor-treated melanoma: Identifying predictors of response and resistance, and markers of biological discordance.

Cancer Cell 2022 Jan 23;40(1):88-102.e7. Epub 2021 Dec 23.

Melanoma Institute Australia, The University of Sydney, Sydney, NSW 2065, Australia; Charles Perkins Centre, The University of Sydney, Sydney, NSW 2006, Australia; Faculty of Medicine and Health, The University of Sydney, Sydney, NSW 2006, Australia; Department of Medical Oncology, Royal North Shore Hospital, Sydney, NSW 2065, Australia; Mater Hospital, Sydney, NSW 2060, Australia. Electronic address:

We concurrently examine the whole genome, transcriptome, methylome, and immune cell infiltrates in baseline tumors from 77 patients with advanced cutaneous melanoma treated with anti-PD-1 with or without anti-CTLA-4. We show that high tumor mutation burden (TMB), neoantigen load, expression of IFNγ-related genes, programmed death ligand expression, low PSMB8 methylation (therefore high expression), and T cells in the tumor microenvironment are associated with response to immunotherapy. No specific mutation correlates with therapy response. A multivariable model combining the TMB and IFNγ-related gene expression robustly predicts response (89% sensitivity, 53% specificity, area under the curve [AUC], 0.84); tumors with high TMB and a high IFNγ signature show the best response to immunotherapy. This model validates in an independent cohort (80% sensitivity, 59% specificity, AUC, 0.79). Except for a JAK3 loss-of-function mutation, for patients who did not respond as predicted there is no obvious biological mechanism that clearly explained their outlier status, consistent with intratumor and intertumor heterogeneity in response to immunotherapy.
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http://dx.doi.org/10.1016/j.ccell.2021.11.012DOI Listing
January 2022

Ask the people: developing guidelines for genomic research with Aboriginal and Torres Strait Islander peoples.

BMJ Glob Health 2021 11;6(11)

Aboriginal and Torres Strait Islander Health, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia

In health and medical research, guidelines are a set of statements and recommendations, whereby experts or stakeholders assess published literature to generate practical advice for a specific audience. This emphasis on guidelines development with expert consultation and published literature is not practical or inclusive when working in disciplines with minimal data and addressing issues that concern under-represented communities. Here we describe the process used for developing guidelines for the conduct of genomic research projects in partnership with Aboriginal and Torres Strait Islander peoples. A new technology with individual and community level ethical and social implications, and First Nations peoples with cultural and community expectations for research. We developed the guidelines through a consultation process that used participatory action research to engage with various stakeholders during multiple rounds of tailored activities. The end product, 'Genomic Partnerships: Guidelines for Genomics Research with Aboriginal and Torres Strait Islander peoples of Queensland' reflects the needs of the end-users and perspectives of the Aboriginal and Torres Strait Islander peoples, communities and organisations that participated. Through this process, we have identified recommendations for developing guidelines with other under-represented communities.
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http://dx.doi.org/10.1136/bmjgh-2021-007259DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8572381PMC
November 2021

Deep learning in cancer diagnosis, prognosis and treatment selection.

Genome Med 2021 09 27;13(1):152. Epub 2021 Sep 27.

Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane, 4006, Australia.

Deep learning is a subdiscipline of artificial intelligence that uses a machine learning technique called artificial neural networks to extract patterns and make predictions from large data sets. The increasing adoption of deep learning across healthcare domains together with the availability of highly characterised cancer datasets has accelerated research into the utility of deep learning in the analysis of the complex biology of cancer. While early results are promising, this is a rapidly evolving field with new knowledge emerging in both cancer biology and deep learning. In this review, we provide an overview of emerging deep learning techniques and how they are being applied to oncology. We focus on the deep learning applications for omics data types, including genomic, methylation and transcriptomic data, as well as histopathology-based genomic inference, and provide perspectives on how the different data types can be integrated to develop decision support tools. We provide specific examples of how deep learning may be applied in cancer diagnosis, prognosis and treatment management. We also assess the current limitations and challenges for the application of deep learning in precision oncology, including the lack of phenotypically rich data and the need for more explainable deep learning models. Finally, we conclude with a discussion of how current obstacles can be overcome to enable future clinical utilisation of deep learning.
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http://dx.doi.org/10.1186/s13073-021-00968-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8477474PMC
September 2021

Tumor Signature Analysis Implicates Hereditary Cancer Genes in Endometrial Cancer Development.

Cancers (Basel) 2021 04 7;13(8). Epub 2021 Apr 7.

Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane 4006, Australia.

Risk of endometrial cancer (EC) is increased ~2-fold for women with a family history of cancer, partly due to inherited pathogenic variants in mismatch repair (MMR) genes. We explored the role of additional genes as explanation for familial EC presentation by investigating germline and EC tumor sequence data from The Cancer Genome Atlas ( = 539; 308 European ancestry), and germline data from 33 suspected familial European ancestry EC patients demonstrating immunohistochemistry-detected tumor MMR proficiency. Germline variants in MMR and 26 other known/candidate EC risk genes were annotated for pathogenicity in the two EC datasets, and also for European ancestry individuals from gnomAD as a population reference set ( = 59,095). Ancestry-matched case-control comparisons of germline variant frequency and/or sequence data from suspected familial EC cases highlighted , , , and as candidates for large-scale risk association studies. Tumor mutational signature analysis identified a microsatellite-high signature for all cases with a germline pathogenic MMR gene variant. Signature analysis also indicated that germline loss-of-function variants in homologous recombination (, , ) or base excision (, ) repair genes can contribute to EC development in some individuals with germline variants in these genes. These findings have implications for expanded therapeutic options for EC cases.
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http://dx.doi.org/10.3390/cancers13081762DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC8067736PMC
April 2021

Radiomics Biomarkers Correlate with CD8 Expression and Predict Immune Signatures in Melanoma Patients.

Mol Cancer Res 2021 06 2;19(6):950-956. Epub 2021 Apr 2.

The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, Queensland, Australia.

Treatment for metastatic melanoma includes targeted and/or immunotherapy. Although many patients respond, only a subset has complete response. As late-stage patients often have multiple tumors in difficult access sites, non-invasive techniques are necessary for the development of predictive/prognostic biomarkers. PET/CT scans from 52 patients with stage III/IV melanoma were assessed and CT image parameters were evaluated as prognostic biomarkers. Analysis indicated patients with high standard deviation or high mean of positive pixels (MPP) had worse progression-free survival ( = 0.00047 and = 0.0014, respectively) and worse overall survival ( = 0.0223 and = 0.0465, respectively). Whole-exome sequencing showed high MPP was associated with mutation status ( = 0.0389). RNA-sequencing indicated patients with immune "cold" signatures had worse survival, which was associated with CT biomarker, MPP4 ( = 0.0284). Multiplex immunofluorescence confirmed a correlation between CD8 expression and image biomarkers ( = 0.0028). IMPLICATIONS: CT parameters have the potential to be cost-effective biomarkers of survival in melanoma, and reflect the tumor immune-microenvironment. VISUAL OVERVIEW: http://mcr.aacrjournals.org/content/molcanres/19/6/950/F1.large.jpg.
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http://dx.doi.org/10.1158/1541-7786.MCR-20-1038DOI Listing
June 2021

Considerations for using population frequency data in germline variant interpretation: Cancer syndrome genes as a model.

Hum Mutat 2021 05 1;42(5):530-536. Epub 2021 Mar 1.

Genetics & Computational Biology, QIMR Berghofer Medical Research Institute, Herston, Queensland, Australia.

Aggregate population genomics data from large cohorts are vital for assessing germline variant pathogenicity. However, there are no specifications on how sequencing quality metrics should be considered, and whether exome-derived and genome-derived allele frequencies should be considered in isolation. Germline genome sequence data were simulated for nine read-depths to identify a minimum acceptable read-depth for detecting variants. gnomAD exome-derived and genome-derived datasets were assessed for read-depth, for six key cancer genes selected for variant curation by ClinGen expert panels. Non-Finnish European allele frequency (AF) or filter AF of coding variants in these genes, assigned into frequency bins using modified ACMG-AMP criteria, was compared between exome-derived and genome-derived datasets. A 30X read-depth achieved acceptable precision and recall for detection of substitutions, but poor recall for small insertions/deletions. Exome-derived and genome-derived datasets exhibited low read-depth for different gene exons. Individual variants were mostly assigned to non-divergent AF bins (>95%) or filter AF bins (>97%). Two major bin divergences were resolved by applying the minimal acceptable read-depth threshold. These findings show the importance of assessing read-depth separately for population datasets sourced from different short-read sequencing technologies before assigning a frequency-based ACMG-AMP classification code for variant interpretation.
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http://dx.doi.org/10.1002/humu.24183DOI Listing
May 2021

DNA methylation patterns identify subgroups of pancreatic neuroendocrine tumors with clinical association.

Commun Biol 2021 02 3;4(1):155. Epub 2021 Feb 3.

University of Sydney, Sydney, New South Wales, 2006, Australia.

Here we report the DNA methylation profile of 84 sporadic pancreatic neuroendocrine tumors (PanNETs) with associated clinical and genomic information. We identified three subgroups of PanNETs, termed T1, T2 and T3, with distinct patterns of methylation. The T1 subgroup was enriched for functional tumors and ATRX, DAXX and MEN1 wild-type genotypes. The T2 subgroup contained tumors with mutations in ATRX, DAXX and MEN1 and recurrent patterns of chromosomal losses in half of the genome with no association between regions with recurrent loss and methylation levels. T2 tumors were larger and had lower methylation in the MGMT gene body, which showed positive correlation with gene expression. The T3 subgroup harboured mutations in MEN1 with recurrent loss of chromosome 11, was enriched for grade G1 tumors and showed histological parameters associated with better prognosis. Our results suggest a role for methylation in both driving tumorigenesis and potentially stratifying prognosis in PanNETs.
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http://dx.doi.org/10.1038/s42003-020-01469-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7859232PMC
February 2021

Verifying explainability of a deep learning tissue classifier trained on RNA-seq data.

Sci Rep 2021 01 29;11(1):2641. Epub 2021 Jan 29.

QIMR Berghofer Medical Research Institute, Brisbane, QLD, 4006, Australia.

For complex machine learning (ML) algorithms to gain widespread acceptance in decision making, we must be able to identify the features driving the predictions. Explainability models allow transparency of ML algorithms, however their reliability within high-dimensional data is unclear. To test the reliability of the explainability model SHapley Additive exPlanations (SHAP), we developed a convolutional neural network to predict tissue classification from Genotype-Tissue Expression (GTEx) RNA-seq data representing 16,651 samples from 47 tissues. Our classifier achieved an average F1 score of 96.1% on held-out GTEx samples. Using SHAP values, we identified the 2423 most discriminatory genes, of which 98.6% were also identified by differential expression analysis across all tissues. The SHAP genes reflected expected biological processes involved in tissue differentiation and function. Moreover, SHAP genes clustered tissue types with superior performance when compared to all genes, genes detected by differential expression analysis, or random genes. We demonstrate the utility and reliability of SHAP to explain a deep learning model and highlight the strengths of applying ML to transcriptome data.
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http://dx.doi.org/10.1038/s41598-021-81773-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7846764PMC
January 2021

Pathogenic germline variants are associated with poor survival in stage III/IV melanoma patients.

Sci Rep 2020 10 19;10(1):17687. Epub 2020 Oct 19.

The University of Queensland Diamantina Institute, The University of Queensland, Woolloongabba, QLD, 4102, Australia.

Patients with late stage resected cutaneous melanoma have poor overall survival (OS) and experience irreversible adverse events from systemic therapy. There is a clinical need to identify biomarkers to predict outcome. Performing germline/tumour whole-exome sequencing of 44 stage III/IV melanoma patients we identified pathogenic germline mutations in CDKN2A, CDK4, ATM, POLH, MRE11A, RECQL4 and XPC, affecting 7/44 patients. These mutations were associated with poor OS (p = 0.0082). We confirmed our findings in The Cancer Genome Atlas (TCGA) human skin cutaneous melanoma cohort where we identified pathogenic variants in 40/455 patients (p = 0.0203). Combining these cohorts (n = 499) further strengthened these findings showing germline carriers had worse OS (p = 0.0009). Additionally, we determined whether tumour mutation burden (TMB) or BRAF status were prognostic markers of survival. Low TMB rate (< 20 Mut/Mb; p = 0.0034) and BRAF p.V600 mutation (p = 0.0355) were associated with worse progression-free survival. Combining these biomarkers indicated that V600 mutant patients had significantly lower TMB (p = 0.0155). This was confirmed in the TCGA (n = 443, p = 0.0007). Integrative analysis showed germline mutation status conferred the highest risk (HR 5.2, 95% CI 1.72-15.7). Stage IV (HR 2.5, 0.74-8.6) and low TMB (HR 2.3, 0.57-9.4) were similar, whereas BRAF V600 status was the weakest prognostic biomarker (HR 1.5, 95% CI 0.44-5.2).
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http://dx.doi.org/10.1038/s41598-020-74956-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7572377PMC
October 2020

Whole-genome sequencing of acral melanoma reveals genomic complexity and diversity.

Nat Commun 2020 10 16;11(1):5259. Epub 2020 Oct 16.

Center for Rare Melanomas, University of Colorado Cancer Center, Aurora, Colorado, USA.

To increase understanding of the genomic landscape of acral melanoma, a rare form of melanoma occurring on palms, soles or nail beds, whole genome sequencing of 87 tumors with matching transcriptome sequencing for 63 tumors was performed. Here we report that mutational signature analysis reveals a subset of tumors, mostly subungual, with an ultraviolet radiation signature. Significantly mutated genes are BRAF, NRAS, NF1, NOTCH2, PTEN and TYRP1. Mutations and amplification of KIT are also common. Structural rearrangement and copy number signatures show that whole genome duplication, aneuploidy and complex rearrangements are common. Complex rearrangements occur recurrently and are associated with amplification of TERT, CDK4, MDM2, CCND1, PAK1 and GAB2, indicating potential therapeutic options.
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http://dx.doi.org/10.1038/s41467-020-18988-3DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7567804PMC
October 2020

Tumor Mutation Burden and Structural Chromosomal Aberrations Are Not Associated with T-cell Density or Patient Survival in Acral, Mucosal, and Cutaneous Melanomas.

Cancer Immunol Res 2020 11 11;8(11):1346-1353. Epub 2020 Sep 11.

Melanoma Institute Australia, The University of Sydney, North Sydney, New South Wales, Australia.

Tumor mutation burden (TMB) has been proposed as a key determinant of immunogenicity in several cancers, including melanoma. The evidence presented thus far, however, is often contradictory and based mostly on RNA-sequencing data for the quantification of immune cell phenotypes. Few studies have investigated TMB across acral, mucosal, and cutaneous melanoma subtypes, which are known to have different TMB. It is also unknown whether chromosomal structural mutations [structural variant (SV) mutations] contribute to the immunogenicity in acral and mucosal melanomas where such aberrations are common. We stained 151 cutaneous and 35 acral and mucosal melanoma patient samples using quantitative IHC and correlated immune infiltrate phenotypes with TMB and other genomic profiles. TMB and SVs did not correlate with the densities of CD8 lymphocytes, CD103 tumor-resident T cells (Trm), CD45RO cells, and other innate and adaptive immune cell subsets in cutaneous and acral/mucosal melanoma tumors, respectively, including in analyses restricted to the site of disease and in a validation cohort. In 43 patients with stage III treatment-naïve cutaneous melanoma, we found that the density of immune cells, particularly Trm, was significantly associated with patient survival, but not with TMB. Overall, TMB and chromosomal structural aberrations are not associated with protective antitumor immunity in treatment-naïve melanoma.
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http://dx.doi.org/10.1158/2326-6066.CIR-19-0835DOI Listing
November 2020

Using whole-genome sequencing data to derive the homologous recombination deficiency scores.

NPJ Breast Cancer 2020 7;6:33. Epub 2020 Aug 7.

Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, QLD Australia.

The homologous recombination deficiency (HRD) score was developed using whole-genome copy number data derived from arrays as a way to infer deficiency in the homologous recombination DNA damage repair pathway (in particular or deficiency) in breast cancer samples. The score has utility in understanding tumour biology and may be indicative of response to certain therapeutic strategies. Studies have used whole-exome sequencing to derive the HRD score, however, with increasing use of whole-genome sequencing (WGS) to characterise tumour genomes, there has yet to be a comprehensive comparison between HRD scores derived by array versus WGS. Here we demonstrate that there is both a high correlation and a good agreement between array- and WGS-derived HRD scores and between the scores derived from WGS and downsampled WGS to represent shallow WGS. For samples with an HRD score close to threshold for stratifying HR proficiency or deficiency there was however some disagreement in the HR status between array and WGS data, highlighting the importance of not relying on a single method of ascertaining the homologous recombination status of a tumour.
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http://dx.doi.org/10.1038/s41523-020-0172-0DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7414867PMC
August 2020

Whole genome landscapes of uveal melanoma show an ultraviolet radiation signature in iris tumours.

Nat Commun 2020 05 15;11(1):2408. Epub 2020 May 15.

QIMR Berghofer Medical Research Institute, Brisbane, QLD, Australia.

Uveal melanoma (UM) is the most common intraocular tumour in adults and despite surgical or radiation treatment of primary tumours, ~50% of patients progress to metastatic disease. Therapeutic options for metastatic UM are limited, with clinical trials having little impact. Here we perform whole-genome sequencing (WGS) of 103 UM from all sites of the uveal tract (choroid, ciliary body, iris). While most UM have low tumour mutation burden (TMB), two subsets with high TMB are seen; one driven by germline MBD4 mutation, and another by ultraviolet radiation (UVR) exposure, which is restricted to iris UM. All but one tumour have a known UM driver gene mutation (GNAQ, GNA11, BAP1, PLCB4, CYSLTR2, SF3B1, EIF1AX). We identify three other significantly mutated genes (TP53, RPL5 and CENPE).
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http://dx.doi.org/10.1038/s41467-020-16276-8DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7229209PMC
May 2020

Mutation Marks an Aggressive Subtype of Mutant Colorectal Cancers.

Cancers (Basel) 2020 May 6;12(5). Epub 2020 May 6.

QIMR Berghofer Medical Research Institute, Herston, QLD 4006, Australia.

Background: WNT activation is a hallmark of colorectal cancer. mutation is present in 15% of colorectal cancers, and the role of mutations in WNT signaling regulators in this context is unclear. Here, we evaluate the mutational landscape of WNT signaling regulators in mutant cancers.

Methods: we performed exome-sequencing on 24 BRAF mutant colorectal cancers and analyzed these data in combination with 175 publicly available BRAF mutant colorectal cancer exomes. We assessed the somatic mutational landscape of WNT signaling regulators, and performed hotspot and driver mutation analyses to identify potential drivers of WNT signaling. The effects of Apc and Braf mutation were modelled, in vivo, using the Apc and Braf/Villin-Cre mouse, respectively.

Results: RNF43 was the most frequently mutated WNT signaling regulator (41%). Mutations in the beta-catenin destruction complex occurred in 48% of cancers. Hotspot analyses identified potential cancer driver genes in the WNT signaling cascade, including MEN1, GNG12 and WNT16. Truncating APC mutation was identified in 20.8% of cancers. Truncating APC mutation was associated with early age at diagnosis (p < 2 × 10), advanced stage (p < 0.01), and poor survival (p = 0.026). Apc/Braf animals had more numerous and larger SI and colonic lesions (p < 0.0001 and p < 0.05, respectively), and a markedly reduced survival (median survival: 3.2 months, p = 8.8 × 10), compared to animals with Apc or Braf mutation alone.

Conclusions: the WNT signaling axis is frequently mutated in BRAF mutant colorectal cancers. WNT16 and MEN1 may be novel drivers of aberrant WNT signaling in colorectal cancer. Co-mutation of BRAF and APC generates an extremely aggressive neoplastic phenotype that is associated with poor patient outcome.
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http://dx.doi.org/10.3390/cancers12051171DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC7281581PMC
May 2020

Running Genomic Analyses in the Cloud.

Stud Health Technol Inform 2019 Aug;266:149-155

QIMR Berghofer Medical Research Institute, Brisbane, Australia.

Genomic testing is rapidly moving into healthcare practice. However it comes with informatics challenges that the healthcare system has not previously faced - the raw data can be hundreds of gigabytes per test, the compute demands can be thousands of CPU hours, and the test can reveal deeply private health-srelated information that can have implications for anyone related to the person tested. While not a panacea, cloud computing has particular properties that can ameliorate some of these difficulties. This paper presents some of the key lessons learned while deploying a set of genomic analyses on cloud computing for Queensland Genomics.
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http://dx.doi.org/10.3233/SHTI190787DOI Listing
August 2019

Whole-genome landscape of mucosal melanoma reveals diverse drivers and therapeutic targets.

Nat Commun 2019 07 18;10(1):3163. Epub 2019 Jul 18.

Department of Pathology, University of California, San Francisco, CA, 94143, USA.

Knowledge of key drivers and therapeutic targets in mucosal melanoma is limited due to the paucity of comprehensive mutation data on this rare tumor type. To better understand the genomic landscape of mucosal melanoma, here we describe whole genome sequencing analysis of 67 tumors and validation of driver gene mutations by exome sequencing of 45 tumors. Tumors have a low point mutation burden and high numbers of structural variants, including recurrent structural rearrangements targeting TERT, CDK4 and MDM2. Significantly mutated genes are NRAS, BRAF, NF1, KIT, SF3B1, TP53, SPRED1, ATRX, HLA-A and CHD8. SF3B1 mutations occur more commonly in female genital and anorectal melanomas and CTNNB1 mutations implicate a role for WNT signaling defects in the genesis of some mucosal melanomas. TERT aberrations and ATRX mutations are associated with alterations in telomere length. Mutation profiles of the majority of mucosal melanomas suggest potential susceptibility to CDK4/6 and/or MEK inhibitors.
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http://dx.doi.org/10.1038/s41467-019-11107-xDOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6639323PMC
July 2019

Molecular Genomic Profiling of Melanocytic Nevi.

J Invest Dermatol 2019 08 14;139(8):1762-1768. Epub 2019 Feb 14.

Melanoma Institute Australia, The University of Sydney, New South Wales, Australia; Sydney Medical School, The University of Sydney, Sydney, New South Wales, Australia.

The benign melanocytic nevus is the most common tumor in humans and rarely transforms into cutaneous melanoma. Elucidation of the nevus genome is required to better understand the molecular steps of progression to melanoma. We performed whole genome sequencing on a series of 14 benign melanocytic nevi consisting of both congenital and acquired types. All nevi had driver mutations in the MAPK signaling pathway, either BRAF V600E or NRAS Q61R/L. No additional definite driver mutations were identified. Somatic mutations in nevi with higher mutation loads showed a predominance of mutational signatures 7a and 7b, consistent with UVR exposure, whereas nevi with lower mutation loads (including all three congenital nevi) had a predominance of the ubiquitous signatures 1 and 5. Two nevi had mutations in promoter regions predicted to bind E26 transformation-specific family transcription factors, as well as subclonal mutations in the TERT promoter. This paper presents whole genome data from melanocytic nevi. We confirm that UVR is involved in the etiology of a subset of nevi. This study also establishes that TERT promoter mutations are present in morphologically benign skin nevi in subclonal populations, which has implications regarding the interpretation of this emerging biomarker in sensitive assays.
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http://dx.doi.org/10.1016/j.jid.2018.12.033DOI Listing
August 2019

Intratumoural Heterogeneity Underlies Distinct Therapy Responses and Treatment Resistance in Glioblastoma.

Cancers (Basel) 2019 Feb 6;11(2). Epub 2019 Feb 6.

Cell and Molecular Biology Department, QIMR Berghofer Medical Research Institute, Brisbane 4006, QLD, Australia.

Glioblastomas are the most common and lethal neoplasms of the central nervous system. Neighbouring glioma cells maintain extreme degrees of genetic and phenotypic variation that form intratumoural heterogeneity. This genetic diversity allows the most adaptive tumour clones to develop treatment resistance, ultimately leading to disease recurrence. We aimed to model this phenomenon and test the effectiveness of several targeted therapeutic interventions to overcome therapy resistance. Heterogeneous tumour masses were first deconstructed into single tumour cells, which were expanded independently as single-cell clones. Single nucleotide polymorphism arrays, whole-genome and RNA sequencing, and CpG methylation analysis validated the unique molecular profile of each tumour clone, which displayed distinct pathologic features, including cell morphology, growth rate, and resistance to temozolomide and ionizing radiation. We also identified variable sensitivities to AURK, CDK, and EGFR inhibitors which were consistent with the heterogeneous molecular alterations that each clone harboured. These targeted therapies effectively eliminated the temozolomide- and/or irradiation-resistant clones and also parental polyclonal cells. Our findings indicate that polyclonal tumours create a dynamic environment that consists of diverse tumour elements and treatment responses. Designing targeted therapies based on a range of molecular profiles can be a more effective strategy to eradicate treatment resistance, recurrence, and metastasis.
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http://dx.doi.org/10.3390/cancers11020190DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6406894PMC
February 2019

Diff-Quik Cytology Smears from Endobronchial Ultrasound Transbronchial Needle Aspiration Lymph Node Specimens as a Source of DNA for Next-Generation Sequencing Instead of Cell Blocks.

Respiration 2019;97(6):525-539. Epub 2019 Feb 7.

Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, Queensland, Australia.

Background: Next-generation sequencing (NGS) in lung cancer specimens from endobronchial ultrasound transbronchial needle aspiration (EBUS-TBNA) is usually performed on formalin-fixed paraffin-embedded cell block material.

Objectives: Since DNA can be damaged by this process, we investigated the potential of using DNA extracted from Diff-Quik cytology smears made for rapid on-site evaluation during EBUS-TBNA.

Methods: In a prospective study, 67 patients undergoing diagnostic EBUS-TBNA were ana-lysed. We compared cell blocks and smears for DNA yields and sequencing (TruSeq Amplicon Cancer Panel) outcomes. Smears were also evaluated for tumour cell fraction and overall cellularity (cell count).

Results: Primary lung cancer was diagnosed in 64 patients and metastatic malignancy in 3 patients. The DNA yield from smears was significantly higher than that obtained from matched cell blocks (mean 1,740 vs. 434 ng; p = 0.001). For 33 cases with matched smears and cell blocks the mutation profiles were similar. Smears with abundant malignant cells (using a cut-off of > 25% tumour cell fraction and > 1,000 cells) accurately predicted high (> 50 ng) DNA yield and therefore success in triaging samples to sequencing. In terms of tissue workflow, using only smears as source DNA for sequencing was an improvement in the use of only cell blocks (54/67 [80.6%] vs. 41/67 [61.2%]); however, the use of cell blocks when smears were not available or did not yield sufficient DNA further improved the success rate to 62/67 (92.5%) cases.

Conclusion: We recommend smears in laboratory workflows as the primary source of DNA for NGS following an EBUS procedure.
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http://dx.doi.org/10.1159/000495661DOI Listing
September 2020

Complex structural rearrangements are present in high-grade dysplastic Barrett's oesophagus samples.

BMC Med Genomics 2019 02 4;12(1):31. Epub 2019 Feb 4.

Surgical Oncology Group, Diamantina Institute, The University of Queensland, Translational Research Institute, Woolloongabba, Brisbane, QLD, 4102, Australia.

Background: Oesophageal adenocarcinoma (EAC) incidence is increasing and has a poor survival rate. Barrett's oesophagus (BE) is a precursor condition that is associated with EAC and often occurs in conjunction with chronic gastro-oesophageal reflux, however many individuals diagnosed with BE never progress to cancer. An understanding of the genomic features of BE and EAC may help with the early identification of at-risk individuals.

Methods: In this study, we assessed the genomic features of 16 BE samples using whole-genome sequencing. These included non-dysplastic samples collected at two time-points from two BE patients who had not progressed to EAC over several years. Seven other non-dysplastic samples and five dysplastic BE samples with high-grade dysplasia were also examined. We compared the genome profiles of these 16 BE samples with 22 EAC samples.

Results: We observed that samples from the two non-progressor individuals had low numbers of somatic single nucleotide variants, indels and structural variation events compared to dysplastic and the remaining non-dysplastic BE. EAC had the highest level of somatic genomic variations. Mutational signature 17, which is common in EAC, was also present in non-dysplastic and dysplastic BE, but was not present in the non-progressors. Many dysplastic samples had mutations in genes previously reported in EAC, whereas only mutations in CDKN2A or in the fragile site genes appeared common in non-dysplastic samples. Rearrangement signatures were used to identify a signature associated with localised complex events such as chromothripsis and breakage fusion-bridge that are characteristic of EACs. Two dysplastic BE samples had a high contribution of this signature and contained evidence of localised rearrangements. Two other dysplastic samples also had regions of localised structural rearrangements. There was no evidence for complex events in non-dysplastic samples.

Conclusions: The presence of complex localised rearrangements in dysplastic samples indicates a need for further investigations into the role such events play in the progression from BE to EAC.
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http://dx.doi.org/10.1186/s12920-019-0476-9DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6360790PMC
February 2019

Phenotypic and molecular dissection of metaplastic breast cancer and the prognostic implications.

J Pathol 2019 02 20;247(2):214-227. Epub 2018 Dec 20.

Department of Histopathology, Sullivan Nicolaides Pathology, Bowen Hills, Australia.

Metaplastic breast carcinoma (MBC) is relatively rare but accounts for a significant proportion of global breast cancer mortality. This group is extremely heterogeneous and by definition exhibits metaplastic change to squamous and/or mesenchymal elements, including spindle, squamous, chondroid, osseous, and rhabdomyoid features. Clinically, patients are more likely to present with large primary tumours (higher stage), distant metastases, and overall, have shorter 5-year survival compared to invasive carcinomas of no special type. The current World Health Organisation (WHO) diagnostic classification for this cancer type is based purely on morphology - the biological basis and clinical relevance of its seven sub-categories are currently unclear. By establishing the Asia-Pacific MBC (AP-MBC) Consortium, we amassed a large series of MBCs (n = 347) and analysed the mutation profile of a subset, expression of 14 breast cancer biomarkers, and clinicopathological correlates, contextualising our findings within the WHO guidelines. The most significant indicators of poor prognosis were large tumour size (T3; p = 0.004), loss of cytokeratin expression (lack of staining with pan-cytokeratin AE1/3 antibody; p = 0.007), EGFR overexpression (p = 0.01), and for 'mixed' MBC, the presence of more than three distinct morphological entities (p = 0.007). Conversely, fewer morphological components and EGFR negativity were favourable indicators. Exome sequencing of 30 cases confirmed enrichment of TP53 and PTEN mutations, and intriguingly, concurrent mutations of TP53, PTEN, and PIK3CA. Mutations in neurofibromatosis-1 (NF1) were also overrepresented [16.7% MBCs compared to ∼5% of breast cancers overall; enrichment p = 0.028; mutation significance p = 0.006 (OncodriveFM)], consistent with published case reports implicating germline NF1 mutations in MBC risk. Taken together, we propose a practically minor but clinically significant modification to the guidelines: all WHO_1 mixed-type tumours should have the number of morphologies present recorded, as a mechanism for refining prognosis, and that EGFR and pan-cytokeratin expression are important prognostic markers. Copyright © 2018 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.
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http://dx.doi.org/10.1002/path.5184DOI Listing
February 2019

Whole genome sequencing of melanomas in adolescent and young adults reveals distinct mutation landscapes and the potential role of germline variants in disease susceptibility.

Int J Cancer 2019 03 21;144(5):1049-1060. Epub 2018 Nov 21.

Melanoma Institute Australia, The University of Sydney, Sydney, Australia.

Cutaneous melanoma accounts for at least >10% of all cancers in adolescents and young adults (AYA, 15-30 years of age) in Western countries. To date, little is known about the correlations between germline variants and somatic mutations and mutation signatures in AYA melanoma patients that might explain why they have developed a cancer predominantly affecting those over 65 years of age. We performed genomic analysis of 50 AYA melanoma patients (onset 10-30 years, median 20); 25 underwent whole genome sequencing (WGS) of both tumor and germline DNA, exome data were retrieved from 12 TCGA AYA cases, and targeted DNA sequencing was conducted on 13 cases. The AYA cases were compared with WGS data from 121 adult cutaneous melanomas. Similar to mature adult cutaneous melanomas, AYA melanomas showed a high mutation burden and mutation signatures of ultraviolet radiation (UVR) damage. The frequencies of somatic mutations in BRAF (96%) and PTEN (36%) in the AYA WGS cohort were double the rates observed in adult melanomas (Q < 6.0 × 10 and 0.028, respectively). Furthermore, AYA melanomas contained a higher proportion of non-UVR-related mutation signatures than mature adult melanomas as a proportion of total mutation burden (p = 2.0 × 10 ). Interestingly, these non-UVR mutation signatures relate to APOBEC or mismatch repair pathways, and germline variants in related genes were observed in some of these cases. We conclude that AYA melanomas harbor some of the same molecular aberrations and mutagenic insults occurring in older adults, but in different proportions. Germline variants that may have conferred disease susceptibility correlated with somatic mutation signatures in a subset of AYA melanomas.
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http://dx.doi.org/10.1002/ijc.31791DOI Listing
March 2019

Telomere sequence content can be used to determine ALT activity in tumours.

Nucleic Acids Res 2018 06;46(10):4903-4918

Telomere Length Regulation Unit, Children's Medical Research Institute, University of Sydney, Westmead, New South Wales, Australia.

The replicative immortality of human cancer cells is achieved by activation of a telomere maintenance mechanism (TMM). To achieve this, cancer cells utilise either the enzyme telomerase, or the Alternative Lengthening of Telomeres (ALT) pathway. These distinct molecular pathways are incompletely understood with respect to activation and propagation, as well as their associations with clinical outcomes. We have identified significant differences in the telomere repeat composition of tumours that use ALT compared to tumours that do not. We then employed a machine learning approach to stratify tumours according to telomere repeat content with an accuracy of 91.6%. Importantly, this classification approach is applicable across all tumour types. Analysis of pathway mutations that were under-represented in ALT tumours, across 1,075 tumour samples, revealed that the autophagy, cell cycle control of chromosomal replication, and transcriptional regulatory network in embryonic stem cells pathways are involved in the survival of ALT tumours. Overall, our approach demonstrates that telomere sequence content can be used to stratify ALT activity in cancers, and begin to define the molecular pathways involved in ALT activation.
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http://dx.doi.org/10.1093/nar/gky297DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC6007693PMC
June 2018

Malignant cells from pleural fluids in malignant mesothelioma patients reveal novel mutations.

Lung Cancer 2018 05 9;119:64-70. Epub 2018 Mar 9.

National Centre for Asbestos Related Disease, University of Western Australia, Nedlands, Western Australia, 6009, Australia. Electronic address:

Objectives: Malignant mesothelioma (MM) is an asbestos related tumour affecting cells of serosal cavities. More than 70% of MM patients develop pleural effusions which contain tumour cells, representing a readily accessible source of malignant cells for genetic analysis. Although common somatic mutations and losses have been identified in solid MM tumours, the characterization of tumour cells within pleural effusions could provide novel insights but is little studied.

Materials And Methods: DNA and RNA were extracted from cells from short term cultures of 27 human MM pleural effusion samples. Whole exome and transcriptome sequencing was performed using the Ion Torrent platform. Somatic mutations were identified using VarScan2 and SomaticSniper. Copy number alterations were identified using ExomeCNV in R. Significant copy number alterations were identified across all samples using GISTIC2.0. The association between tumour intrinsic properties and survival was analyzed using the Cox proportional hazards regression model.

Results: We identified BAP1, CDKN2A and NF2 alterations in the cells from MM pleural effusions at a higher frequency than what is typically seen in MM tumours from surgical series. The median mutation rate was 1.09 mutations/Mb. TRAF7 and LATS2 alterations were also identified at a high frequency (66% and 59% respectively). Novel regions of interest were identified, including alterations in FGFR3, and the regions 19p13.3, 8p23.1 and 1p36.32.

Conclusion: Short term cultures of tumour cells from MM pleural effusions offer an accessible alternative to surgical tumour biopsies in the study of MM genomics and reveal novel mutations of interest. Pleural effusion tumour cells provide an opportunity for the monitoring of tumour dynamics, treatment response and the clonal evolution of MM tumours.
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http://dx.doi.org/10.1016/j.lungcan.2018.03.009DOI Listing
May 2018

Mixed ductal-lobular carcinomas: evidence for progression from ductal to lobular morphology.

J Pathol 2018 04 9;244(4):460-468. Epub 2018 Mar 9.

Centre for Clinical Research, Faculty of Medicine, The University of Queensland, Brisbane, Australia.

Mixed ductal-lobular carcinomas (MDLs) show both ductal and lobular morphology, and constitute an archetypal example of intratumoural morphological heterogeneity. The mechanisms underlying the coexistence of these different morphological entities are poorly understood, although theories include that these components either represent 'collision' of independent tumours or evolve from a common ancestor. We performed comprehensive clinicopathological analysis of a cohort of 82 MDLs, and found that: (1) MDLs more frequently coexist with ductal carcinoma in situ (DCIS) than with lobular carcinoma in situ (LCIS); (2) the E-cadherin-catenin complex was normal in the ductal component in 77.6% of tumours; and (3) in the lobular component, E-cadherin was almost always aberrantly located in the cytoplasm, in contrast to invasive lobular carcinoma (ILC), where E-cadherin is typically absent. Comparative genomic hybridization and multiregion whole exome sequencing of four representative cases revealed that all morphologically distinct components within an individual case were clonally related. The mutations identified varied between cases; those associated with a common clonal ancestry included BRCA2, TBX3, and TP53, whereas those associated with clonal divergence included CDH1 and ESR1. Together, these data support a model in which separate morphological components of MDLs arise from a common ancestor, and lobular morphology can arise via a ductal pathway of tumour progression. In MDLs that present with LCIS and DCIS, the clonal divergence probably occurs early, and is frequently associated with complete loss of E-cadherin expression, as in ILC, whereas, in the majority of MDLs, which present with DCIS but not LCIS, direct clonal divergence from the ductal to the lobular phenotype occurs late in tumour evolution, and is associated with aberrant expression of E-cadherin. The mechanisms driving the phenotypic change may involve E-cadherin-catenin complex deregulation, but are yet to be fully elucidated, as there is significant intertumoural heterogeneity, and each case may have a unique molecular mechanism. © 2018 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of Pathological Society of Great Britain and Ireland.
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http://dx.doi.org/10.1002/path.5040DOI Listing
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5873281PMC
April 2018

Germline and somatic variant identification using BGISEQ-500 and HiSeq X Ten whole genome sequencing.

PLoS One 2018 10;13(1):e0190264. Epub 2018 Jan 10.

Department of Genetics and Computational Biology, QIMR Berghofer Medical Research Institute, Brisbane, Queensland, Australia.

Technological innovation and increased affordability have contributed to the widespread adoption of genome sequencing technologies in biomedical research. In particular large cancer research consortia have embraced next generation sequencing, and have used the technology to define the somatic mutation landscape of multiple cancer types. These studies have primarily utilised the Illumina HiSeq platforms. In this study we performed whole genome sequencing of three malignant pleural mesothelioma and matched normal samples using a new platform, the BGISEQ-500, and compared the results obtained with Illumina HiSeq X Ten. Germline and somatic, single nucleotide variants and small insertions or deletions were independently identified from data aligned human genome reference. The BGISEQ-500 and HiSeq X Ten platforms showed high concordance for germline calls with genotypes from SNP arrays (>99%). The germline and somatic single nucleotide variants identified in both sequencing platforms were highly concordant (86% and 72% respectively). These results indicate the potential applicability of the BGISEQ-500 platform for the identification of somatic and germline single nucleotide variants by whole genome sequencing. The BGISEQ-500 datasets described here represent the first publicly-available cancer genome sequencing performed using this platform.
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http://journals.plos.org/plosone/article?id=10.1371/journal.pone.0190264PLOS
http://www.ncbi.nlm.nih.gov/pmc/articles/PMC5761881PMC
February 2018

Homologous Recombination DNA Repair Pathway Disruption and Retinoblastoma Protein Loss Are Associated with Exceptional Survival in High-Grade Serous Ovarian Cancer.

Clin Cancer Res 2018 02 23;24(3):569-580. Epub 2017 Oct 23.

Peter MacCallum Cancer Centre, Melbourne, Victoria, Australia.

Women with epithelial ovarian cancer generally have a poor prognosis; however, a subset of patients has an unexpected dramatic and durable response to treatment. We sought to identify clinical, pathological, and molecular determinants of exceptional survival in women with high-grade serous cancer (HGSC), a disease associated with the majority of ovarian cancer deaths. We evaluated the histories of 2,283 ovarian cancer patients and, after applying stringent clinical and pathological selection criteria, identified 96 with HGSC that represented significant outliers in terms of treatment response and overall survival. Patient samples were characterized immunohistochemically and by genome sequencing. Different patterns of clinical response were seen: long progression-free survival (Long-PFS), multiple objective responses to chemotherapy (Multiple Responder), and/or greater than 10-year overall survival (Long-Term Survivors). Pathogenic germline and somatic mutations in genes involved in homologous recombination (HR) repair were enriched in all three groups relative to a population-based series. However, 29% of 10-year survivors lacked an identifiable HR pathway alteration, and tumors from these patients had increased Ki-67 staining. CD8 tumor-infiltrating lymphocytes were more commonly present in Long-Term Survivors. RB1 loss was associated with long progression-free and overall survival. HR deficiency and RB1 loss were correlated, and co-occurrence was significantly associated with prolonged survival. There was diversity in the clinical trajectory of exceptional survivors associated with multiple molecular determinants of exceptional outcome in HGSC patients. Concurrent HR deficiency and RB1 loss were associated with favorable outcomes, suggesting that co-occurrence of specific mutations might mediate durable responses in such patients. .
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http://dx.doi.org/10.1158/1078-0432.CCR-17-1621DOI Listing
February 2018

and Mutations Co-occur and Cooperate in Low-Grade Serous Ovarian Carcinomas.

Cancer Res 2017 08 23;77(16):4268-4278. Epub 2017 Jun 23.

Centre for Cancer Research, The Westmead Institute for Medical Research, Sydney, New South Wales, Australia.

Low-grade serous ovarian carcinomas (LGSC) are associated with a poor response to chemotherapy and are molecularly characterized by RAS pathway activation. Using exome and whole genome sequencing, we identified recurrent mutations in the protein translational regulator and in , and RAS pathway mutations were mutually exclusive; however, we found significant co-occurrence of mutations in and Missense mutations were clustered at the N-terminus of the protein in a region associated with its role in ensuring translational initiation fidelity. Coexpression of mutant and proteins promoted proliferation and clonogenic survival in LGSC cells, providing the first example of co-occurring, growth-promoting mutational events in ovarian cancer. .
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http://dx.doi.org/10.1158/0008-5472.CAN-16-2224DOI Listing
August 2017
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