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High-grade serous ovarian carcinoma (HGSOC) is the most genomically complex cancer, characterized by ubiquitous TP53 mutation, profound chromosomal instability, and heterogeneity. The mutational processes driving chromosomal instability in HGSOC can be distinguished by specific copy number signatures. To develop clinically relevant models of these mutational processes we derived 15 continuous HGSOC patient-derived organoids (PDOs) and characterized them using bulk transcriptomic, bulk genomic, single-cell genomic, and drug sensitivity assays. We show that HGSOC PDOs comprise communities of different clonal populations and represent models of different causes of chromosomal instability including homologous recombination deficiency, chromothripsis, tandem-duplicator phenotype, and whole genome duplication. We also show that these PDOs can be used as exploratory tools to study transcriptional effects of copy number alterations as well as compound-sensitivity tests. In summary, HGSOC PDO cultures provide validated genomic models for studies of specific mutational processes and precision therapeutics.

Chromosomal instability (CIN) results in the accumulation of large-scale losses, gains, and rearrangements of DNA(1). The broad genomic complexity caused by CIN is a hallmark of cancer(2), however, there is no systematic framework to measure different types of CIN and their impact on clinical phenotypes pan-cancer. Here, we evaluate the extent, diversity and origin of chromosomal instability across 7,880 tumours representing 33 cancer types. We present a compendium of 17 copy number signatures characterising specific types of CIN, with putative aetiologies supported by multiple independent data sources. The signatures predict drug response and identify new drug targets. Our framework refines the understanding of impaired homologous recombination, one of the most therapeutically targetable types of CIN. Our results illuminate a fundamental structure underlying genomic complexity in human cancers and provide a resource to guide future CIN research.

Supplementary Table from The Genomic Landscape of Early-Stage Ovarian High-Grade Serous Carcinoma

Purpose:Ovarian high-grade serous carcinoma (HGSC) is usually diagnosed at late stage. We investigated whether late-stage HGSC has unique genomic characteristics consistent with acquisition of evolutionary advantage compared with early-stage tumors.Experimental Design:We performed targeted next-generation sequencing and shallow whole-genome sequencing (sWGS) on pretreatment samples from 43 patients with FIGO stage I–IIA HGSC to investigate somatic mutations and copy-number (CN) alterations (SCNA). We compared results to pretreatment samples from 52 patients with stage IIIC/IV HGSC from the BriTROC-1 study.Results:Age of diagnosis did not differ between early-stage and late-stage patients (median 61.3 years vs. 62.3 years, respectively). TP53 mutations were near-universal in both cohorts (89% early-stage, 100% late-stage), and there were no significant differences in the rates of other somatic mutations, including BRCA1 and BRCA2. We also did not observe cohort-specific focal SCNA that could explain biological behavior. However, ploidy was higher in late-stage (median, 3.0) than early-stage (median, 1.9) samples. CN signature exposures were significantly different between cohorts, with greater relative signature 3 exposure in early-stage and greater signature 4 in late-stage. Unsupervised clustering based on CN signatures identified three clusters that were prognostic.Conclusions:Early-stage and late-stage HGSCs have highly similar patterns of mutation and focal SCNA. However, CN signature analysis showed that late-stage disease has distinct signature exposures consistent with whole-genome duplication. Further analyses will be required to ascertain whether these differences reflect genuine biological differences between early-stage and late-stage or simply time-related markers of evolutionary fitness.See related commentary by Yang et al., p. 2730

The drivers of recurrence and resistance in ovarian high grade serous carcinoma (HGSC) remain unclear. We established BriTROC-1 to investigate the acquisition of resistance by collecting tumour biopsies from women with recurrent ovarian HGSC that had relapsed following at least one line of platinum-based chemotherapy. Patients underwent biopsy or secondary debulking surgery, with tumour samples fixed in methanol-based fixative. Normal and tumour DNA samples underwent tagged-amplicon panel sequencing. Tumour DNA underwent shallow whole genome sequencing (sWGS). Tissue microarrays (TMA), created from diagnosis samples, were stained for CD3, CD8, CD20 and FoxP3. 276 patients were recruited (209 platinum-sensitive, 67 platinum-resistant). Panel sequencing showed close concordance between diagnosis and relapse, with only 4 discordant cases, and no revertant mutations inBRCA1orBRCA2were identified in relapse samples. CN signatures were strongly correlated with immune cell infiltration. There was very strong concordance in copy number (CN) between diagnosis and relapse, with no significant difference in purity, ploidy or focal somatic CN alterations, even when stratified by platinum sensitivity or prior chemotherapy lines. Small increases in CN signature 3 and 7 exposure were observed between diagnosis and relapse across the whole cohort but were not present in matched sample pairs. Diagnosis samples from patients with primary platinum resistance had increased rates ofCCNE1andKRASamplification and CN signature 6 exposure. The HGSC genome is remarkably stable between diagnosis and relapse and acquired chemotherapy resistance does not select for common copy number drivers. We have identified new genomic events at diagnosis, includingKRASamplification and CN signature 6 exposure, that are associated with primary platinum resistance.

High grade serous ovarian carcinoma (HGSOC) is characterised by poor outcome and extreme chromosome instability (CIN). Therapies targeting centrosome amplification (CA), a key mediator of chromosome missegregation and CIN, may have significant clinical utility in HGSOC. However, the prevalence of CA in HGSOC, its relationship to genomic biomarkers of CIN and its potential impact on therapeutic response have not been defined. Using high-throughput multi-regional microscopy on 287 clinical HGSOC tumour tissues and 73 ovarian cancer cell lines, we show that CA through centriole overduplication is a highly recurrent and heterogeneous feature of HGSOC and is strongly associated with CIN and genome subclonality. Cell-based studies showed that high prevalence CA is phenocopied in ovarian cancer cell lines, and that high CA is associated with increased multi-treatment resistance; most notably to paclitaxel which is the most common treatment used in HGSOC. CA in HGSOC may therefore present a potential driver of tumour evolution and a powerful biomarker for response to standard-of-care treatment.

High-grade serous ovarian carcinoma (HGSOC) is the most genomically complex cancer, characterised by ubiquitous TP53 mutation, profound chromosomal instability and heterogeneity. The mutational processes driving chromosomal instability in HGSOC can be distinguished by specific copy number signatures. To develop clinically relevant models of these mutational processes we derived 15 continuous HGSOC patient-derived organoids (PDOs). We carried out detailed bulk transcriptomic, bulk genomic, single cell genomic, and drug sensitivity characterisation of the organoids. We show that PDOs comprise communities of different clonal populations and represent models of different causes of chromosomal instability including homologous recombination deficiency, chromothripsis, tandem-duplicator phenotype and whole genome duplication. We also show that these PDOs can be used as exploratory tools to study transcriptional effects of copy number alterations as well as compound-sensitivity tests. In summary, HGSOC PDO cultures provide a genomic tool for studies of specific mutational processes and precision therapeutics.

PurposeHigh grade serous carcinoma (HGSC) is the commonest type of ovarian cancer. Nearly all HGSC cases are diagnosed at late stage and it is not clear whether early stage HGSC has unique characteristics compared to late stage tumours.Experimental DesignWe analysed samples from 45 patients with FIGO stage I - IIA HGSC - 40 from the pathology archives of three large UK cancer centres and 5 from the BriTROC-1 study. We performed shallow whole genome sequencing (sWGS) and targeted next generation sequencing to investigate somatic mutations and copy number alterations. We compared results to 51 stage IIIC/IV HGSC patients from the BriTROC-1 study.ResultsThere was no difference in median age between the early stage (median 61.3 years, range 40-84) and late stage (median 62.3 years, range 34-76) patients at diagnosis. TP53 mutations were near-universal (92% early stage, 100% late stage samples) and there were no significant differences in the rates of other somatic mutations, including BRCA1 and BRCA2, or focal copy number alterations between early- and late-stage cohorts. There were also no unique amplifications or deletions in either cohort. However, median ploidy was greater in late stage (median 3.1) than early stage (median 2.0) samples. In addition, there were higher numbers of breakpoints per 10MB and per chromosome arm and higher absolute copy number in late stage than early stage cohorts; early stage samples had longer segment length. Overall copy number signature exposures were significantly different between early and late stage samples with greater signature 3 exposure in early stage and greater signature 4 in late stage. Both simplex plot and unsupervised hierarchical clustering suggested that a subset of late stage samples retain early stage appearances with high signature 3 and co-clustering with the early stage samplesConclusionsThese data suggest that there are no unique mutations or focal copy number alterations in early stage HGSC. However, whole genome duplication is significantly more common in late-stage disease, suggesting evolution during disease progression. However, a subset of late stage HGSC retains early-stage features, which are associated with improved overall survival.

Background: High grade serous carcinoma (HGSC) is the most common and poorest prognosis subtype of ovarian cancer. The large majority of patients present with advanced (stage IIIC or IV) disease with a median survival of only 3-4 years. By contrast, approximately 10% patients are diagnosed with early stage disease, confined to the ovary/fallopian tube, of whom 90% are cured with surgery and platinum-based chemotherapy. Beyond TP53 mutation, classic activating oncogene mutations are rare in HGSC. Rather, HGSC is marked by extreme copy number (CN) abnormalities, and this complexity has prevented detailed understanding of the mutational processes underpinning outcomes in HGSC. We have used shallow whole genome sequencing (sWGS) to develop novel CN signatures that are able to deconvolute the complexity of HGSC genomes. However, nearly all genomics studies in HGSC have examined advanced stage disease, and little is known about the genomics of early stage HGSC - specifically, it is unclear whether these tumors are identified purely by chance or whether they represent a specific subset that does not metastasize. Hypotheses: We hypothesized that early stage HGSC has a distinct copy number landscape compared to stage IIIC/IV disease. Methods and results: We have identified 43 cases of FIGO stage I-IIA HGSC from the pathology archives of three large London Gynaecological Cancer Centres and 52 late-stage (stage IIIC-IV) cases from BriTROC-1 cohort. Median age at diagnosis was 61.3 years vs 62.3 years respectively. There were no significant differences in mutation rates of TP53 and BRCA1/2, and TP53 mutations were near-universal in both cohorts. We also did not find cohort-specific focal SCNA that could explain biological behavior. However, ploidy was significant higher in late-stage (median 3.0) than early-stage (median 1.9) samples. CN signature exposures were significantly different between early and late stage cohorts. Relative exposure of signature 3 was greater in early-stage and greater signature 4 in late-stage. Unsupervised clustering based on CN signatures identified three clusters that were prognostic. Summary:This project identifed that early stage and late stage HGSC have highly similar patterns of mutation and focal SCNA. However, genome-wide analysis indicates that the abnormalities seen in advanced disease are not present in early stage disease, which may represent a discrete subset with reduced metastatic potential. By identifying and characterizing the copy number signature changes, these data suggest that diagnosis at early-stage might reflect biological differences and not fortuitous chance. These data improve understanding of HGSC biology and may reveal potential new treatment strategies. Citation Format: Zhao Cheng, Hasan B. Mirza, Darren P. Ennis, Philip Smith, Lena Morrill Gavarró, Chishimba Sokota, Gaia Giannone, Teodora Goranova, Thomas Bradley, Anna Piskorz, Michelle Lockley, Baljeet Kaur, Naveena Singh, Laura A. Tookman, Jonathan Krell, Jackie McDermott, Geoff Macintyre, Florian Markowetz, James D. Brenton, Iain A. McNeish. The copy number landscape of early stage ovarian high grade serous carcinoma [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 53.

Human liver cancer research currently lacks in vitro models that can faithfully recapitulate the pathophysiology of the original tumor. We recently described a novel, near-physiological organoid culture system, wherein primary human healthy liver cells form long-term expanding organoids that retain liver tissue function and genetic stability. Here we extend this culture system to the propagation of primary liver cancer (PLC) organoids from three of the most common PLC subtypes: hepatocellular carcinoma (HCC), cholangiocarcinoma (CC) and combined HCC/CC (CHC) tumors. PLC-derived organoid cultures preserve the histological architecture, gene expression and genomic landscape of the original tumor, allowing for discrimination between different tumor tissues and subtypes, even after long-term expansion in culture in the same medium conditions. Xenograft studies demonstrate that the tumorogenic potential, histological features and metastatic properties of PLC-derived organoids are preserved in vivo. PLC-derived organoids are amenable for biomarker identification and drug-screening testing and led to the identification of the ERK inhibitor SCH772984 as a potential therapeutic agent for primary liver cancer. We thus demonstrate the wide-ranging biomedical utilities of PLC-derived organoid models in furthering the understanding of liver cancer biology and in developing personalized-medicine approaches for the disease.