LRP1B deletion in high-grade serous ovarian cancers is associated with acquired chemotherapy resistance to liposomal doxorubicin

Radiogenomics of High-Grade Serous Ovarian Cancer: Multireader Multi-Institutional Study from the Cancer Genome Atlas Ovarian Cancer Imaging Research Group

Purpose To evaluate interradiologist agreement on assessments of computed tomography (CT) imaging features of high-grade serous ovarian cancer (HGSOC), to assess their associations with time-to-disease progression (TTP) and HGSOC transcriptomic profiles (Classification of Ovarian Cancer [CLOVAR]), and to develop an imaging-based risk score system to predict TTP and CLOVAR profiles. Materials and Methods This study was a multireader, multi-institutional, institutional review board-approved, HIPAA-compliant retrospective analysis of 92 patients with HGSOC (median age, 61 years) with abdominopelvic CT before primary cytoreductive surgery available through the Cancer Imaging Archive. Eight radiologists from the Cancer Genome Atlas Ovarian Cancer Imaging Research Group developed and independently recorded the following CT features: characteristics of primary ovarian mass(es), presence of definable mesenteric implants and infiltration, presence of other implants, presence and distribution of peritoneal spread, presence and size of pleural effusions and ascites, lymphadenopathy, and distant metastases. Interobserver agreement for CT features was assessed, as were univariate and multivariate associations with TTP and CLOVAR mesenchymal profile (worst prognosis). Results Interobserver agreement for some features was strong (eg, α = .78 for pleural effusion and ascites) but was lower for others (eg, α = .08 for intraparenchymal splenic metastases). Presence of peritoneal disease in the right upper quadrant (P = .0003), supradiaphragmatic lymphadenopathy (P = .0004), more peritoneal disease sites (P = .0006), and nonvisualization of a discrete ovarian mass (P = .0037) were associated with shorter TTP. More peritoneal disease sites (P = .0025) and presence of pouch of Douglas implants (P = .0045) were associated with CLOVAR mesenchymal profile. Combinations of imaging features contained predictive signal for TTP (concordance index = 0.658; P = .0006) and CLOVAR profile (mean squared deviation = 1.776; P = .0043). Conclusion These results provide some evidence of the clinical and biologic validity of these image features. Interobserver agreement is strong for some features, but could be improved for others. ^© RSNA, 2017 Online supplemental material is available for this article.

Comprehensive genomic profiling of different subtypes of nasopharyngeal carcinoma reveals similarities and differences to guide targeted therapy

BACKGROUND

To date, no targeted therapy has been approved for nasopharyngeal carcinoma (NPC), and this underscores the need for an in-depth understanding of clinically relevant genomic alterations (CRGAs).

METHODS

Comprehensive genomic profiling was performed for 190 NPC patients, including 20 patients with nasopharyngeal adenocarcinoma (NPAC), 62 patients with nasopharyngeal squamous cell carcinoma (NPSCC), and 108 patients with nasopharyngeal undifferentiated carcinoma (NPUC). The associations of genes and pathways with subtypes, Epstein-Barr virus (EBV) infections, and the tumor mutation burden (TMB) were statistically evaluated.

RESULTS

Although the overall rates of genomic alterations were similar, the 3 NPC subtypes exhibited different mutational landscapes. Notably, mutations in a proven-treatable target gene, isocitrate dehydrogenase 2 (IDH2), were significantly associated with NPUC but not with NPAC or NPSCC. The top 5 ranked CRGAs included CDKN2A (29%), IDH2 (16%), SMARCB1 (7%), PIK3CA (6%), and NF1 (5%) in NPUC; CDKN2A (27%), PIK3CA (23%), FBXW7 (11%), PTEN (11%), and EGFR (8%) in NPSCC; and CDKN2A (20%), KRAS (15%), CCND1 (10%), MAP3K1 (10%), and NOTCH1 (10%) in NPAC. The incidence of EBV infections significantly correlated with the subtypes and with TP53, CDKN2A, and CDKN2B. The TMB status correlated with the subtypes and with LRP1B, FBXW7, and PIK3CA mutations as well as DNA repair, phosphoinositide 3-kinase/mammalian target of rapamycin, and mitogen-activated protein kinase pathways.

CONCLUSIONS

These results indicate that different NPC subtypes harbor different CRGAs. Both EBV infections and the TMB are associated with the NPC subtypes as well as the alterations of individual genes and pathways. The high frequency of IDH2 mutations in NPUC may facilitate potential targeted therapy and will ultimately point to new therapeutic strategies. Cancer 2017;123:3628-37. © 2017 American Cancer Society.

Revealing cancer subtypes with higher-order correlations applied to imaging and omics data

Background

Patient stratification to identify subtypes with different disease manifestations, severity, and expected survival time is a critical task in cancer diagnosis and treatment. While stratification approaches using various biomarkers (including high-throughput gene expression measurements) for patient-to-patient comparisons have been successful in elucidating previously unseen subtypes, there remains an untapped potential of incorporating various genotypic and phenotypic data to discover novel or improved groupings.

Methods

Here, we present HOCUS, a unified analytical framework for patient stratification that uses a community detection technique to extract subtypes out of sparse patient measurements. HOCUS constructs a patient-to-patient network from similarities in the data and iteratively groups and reconstructs the network into higher order clusters. We investigate the merits of using higher-order correlations to cluster samples of cancer patients in terms of their associations with survival outcomes.

Results

In an initial test of the method, the approach identifies cancer subtypes in mutation data of glioblastoma, ovarian, breast, prostate, and bladder cancers. In several cases, HOCUS provides an improvement over using the molecular features directly to compare samples. Application of HOCUS to glioblastoma images reveals a size and location classification of tumors that improves over human expert-based stratification.

Conclusions

Subtypes based on higher order features can reveal comparable or distinct groupings. The distinct solutions can provide biologically- and treatment-relevant solutions that are just as significant as solutions based on the original data.

Electronic supplementary material

The online version of this article (doi:10.1186/s12920-017-0256-3) contains supplementary material, which is available to authorized users.

Reversion of BRCA1/2 Germline Mutations Detected in Circulating Tumor DNA From Patients With High-Grade Serous Ovarian Cancer

Purpose Germline BRCA1 or BRCA2 mutations in patients with high-grade serous ovarian cancer (HGSC) are associated with favorable responses to chemotherapy. However, secondary intragenic (reversion) mutations that restore protein function lead to clinically significant rates of acquired resistance. The goal of this study was to determine whether reversion mutations could be found in an unbiased manner in circulating cell-free DNA (cfDNA) to predict treatment response in HGSC. Patients and Methods Plasma and tumor samples were obtained from 30 patients with HGSC with either BRCA1 or BRCA2 germline mutation. Two cohorts were ascertained: patients with a malignancy before undergoing primary HGSC debulking surgery (n = 14) or patients at disease recurrence (n = 16). Paired tumor and plasma samples were available for most patients (24 of 30). Targeted amplicon, next-generation sequencing was performed using primers that flanked germline mutations, whose design did not rely on prior knowledge of reversion sequences. Results Five patients were identified with intragenic mutations predicted to restore BRCA1/2 open reading frames, including two patients with multiple independent reversion alleles. Reversion mutations were only detected in tumor samples from patients with recurrent disease (five of 16) and only in cfDNA from patients with a tumor-detected reversion (three of five). Findings from a rapid autopsy of a patient with multiple independent reversions indicated that reversion-allele frequency in metastatic sites is an important determinant of assay sensitivity. Abundance of tumor-derived DNA in total cell-free DNA, as measured by TP53 mutant allele frequency, also affected assay sensitivity. All patients with reversions detected in tumor-derived DNA were resistant to platin- or poly ADP ribose polymerase inhibitor-based chemotherapy. Conclusion Reversion mutations can be detected in an unbiased analysis of cfDNA, suggesting clinical utility for predicting chemotherapy response in recurrent HGSC.

Molecular Characterization of Epithelial Ovarian Cancer: Implications for Diagnosis and Treatment

Epithelial ovarian cancer is a highly heterogeneous disease characterized by multiple histological subtypes. Molecular diversity has been shown to occur within specific histological subtypes of epithelial ovarian cancer, between different tumors of an individual patient, as well as within individual tumors. Recent advances in the molecular characterization of epithelial ovarian cancer tumors have provided the basis for a simplified classification scheme in which these cancers are classified as either type I or type II tumors, and these two categories have implications regarding disease pathogenesis and prognosis. Molecular analyses, primarily based on next-generation sequencing, otherwise known as high-throughput sequencing, are allowing for further refinement of ovarian cancer classification, facilitating the elucidation of the site(s) of precursor lesions of high-grade serous ovarian cancer, and providing insight into the processes of clonal selection and evolution that may be associated with development of chemoresistance. Potential therapeutic targets have been identified from recent molecular profiling studies of these tumors, and the effectiveness and safety of a number of specific targeted therapies have been evaluated or are currently being studied for the treatment of women with this disease.

FGFR1 and NTRK3 actionable alterations in "Wild-Type" gastrointestinal stromal tumors

Background

About 10–15% of adult, and most pediatric, gastrointestinal stromal tumors (GIST) lack mutations in KIT, PDGFRA, SDHx, or RAS pathway components (KRAS, BRAF, NF1). The identification of additional mutated genes in this rare subset of tumors can have important clinical benefit to identify altered biological pathways and select targeted therapies.

Methods

We performed comprehensive genomic profiling (CGP) for coding regions in more than 300 cancer-related genes of 186 GISTs to assess for their somatic alterations.

Results

We identified 24 GIST lacking alterations in the canonical KIT/PDGFRA/RAS pathways, including 12 without SDHx alterations. These 24 patients were mostly adults (96%). The tumors had a 46% rate of nodal metastases. These 24 GIST were more commonly mutated at 7 genes: ARID1B, ATR, FGFR1, LTK, SUFU, PARK2 and ZNF217. Two tumors harbored FGFR1 gene fusions (FGFR1–HOOK3, FGFR1–TACC1) and one harbored an ETV6–NTRK3 fusion that responded to TRK inhibition. In an independent sample set, we identified 5 GIST cases lacking alterations in the KIT/PDGFRA/SDHx/RAS pathways, including two additional cases with FGFR1–TACC1 and ETV6–NTRK3 fusions.

Conclusions

Using patient demographics, tumor characteristics, and CGP, we show that GIST lacking alterations in canonical genes occur in younger patients, frequently metastasize to lymph nodes, and most contain deleterious genomic alterations, including gene fusions involving FGFR1 and NTRK3. If confirmed in larger series, routine testing for these translocations may be indicated for this subset of GIST. Moreover, these findings can be used to guide personalized treatments for patients with GIST.

Trial registration NCT 02576431. Registered October 12, 2015

Electronic supplementary material

The online version of this article (doi:10.1186/s12967-016-1075-6) contains supplementary material, which is available to authorized users.

Common fragile sites (CFS) and extremely large CFS genes are targets for human papillomavirus integrations and chromosome rearrangements in oropharyngeal squamous cell carcinoma

Common fragile sites (CFS) are chromosome regions that are prone to form gaps or breaks in response to DNA replication stress. They are often found as hotspots for sister chromatid exchanges, deletions, and amplifications in different cancers. Many of the CFS regions are found to span genes whose genomic sequence is greater than 1 Mb, some of which have been demonstrated to function as important tumor suppressors. CFS regions are also hotspots for human papillomavirus (HPV) integrations in cervical cancer. We used mate-pair sequencing to examine HPV integration events and chromosomal structural variations in 34 oropharyngeal squamous cell carcinoma (OPSCC). We used endpoint PCR and Sanger sequencing to validate each HPV integration event and found HPV integrations preferentially occurred within CFS regions similar to what is observed in cervical cancer. We also found that many of the chromosomal alterations detected also occurred at or near the cytogenetic location of CFSs. Several large genes were also found to be recurrent targets of rearrangements, independent of HPV integrations, including CSMD1 (2.1Mb), LRP1B (1.9Mb), and LARGE1 (0.7Mb). Sanger sequencing revealed that the nucleotide sequences near to identified junction sites contained repetitive and AT-rich sequences that were shown to have the potential to form stem-loop DNA secondary structures that might stall DNA replication fork progression during replication stress. This could then cause increased instability in these regions which could lead to cancer development in human cells. Our findings suggest that CFSs and some specific large genes appear to play important roles in OPSCC. © 2016 Wiley Periodicals, Inc.

Genetic and epigenetic heterogeneity of epithelial ovarian cancer and the clinical implications for molecular targeted therapy

Epithelial ovarian cancer (EOC) is the most lethal gynaecological malignancy, and tumoural heterogeneity (TH) has been blamed for treatment failure. The genomic and epigenomic atlas of EOC varies significantly with tumour histotype, grade, stage, sensitivity to chemotherapy and prognosis. Rapidly accumulating knowledge about the genetic and epigenetic events that control TH in EOC has facilitated the development of molecular-targeted therapy. Poly (ADP-ribose) polymerase (PARP) inhibitors, designed to target homologous recombination, are poised to change how breast cancer susceptibility gene (BRCA)-related ovarian cancer is treated. Epigenetic treatment regimens being tested in clinical or preclinical studies could provide promising novel treatment approaches and hope for improving patient survival.

Recently identified drug resistance biomarkers in ovarian cancer

Ovarian cancer, consisting mainly of ovarian carcinoma, is the most lethal gynecologic malignancy. Improvements in outcome for patients with advanced-stage disease are limited by intrinsic and acquired chemoresistance and by tumor heterogeneity at different anatomic sites and along disease progression. Molecules and cellular pathways mediating chemoresistance appear to be different for the different histological types of ovarian carcinoma, with most recent research focusing on serous and clear cell carcinoma. This review discusses recent data implicating various biomarkers in chemoresistance in this cancer, with focus on studies in which clinical specimens have been central.

Rethinking ovarian cancer II: reducing mortality from high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) accounts for 70-80% of ovarian cancer deaths, and overall survival has not changed significantly for several decades. In this Opinion article, we outline a set of research priorities that we believe will reduce incidence and improve outcomes for women with this disease. This 'roadmap' for HGSOC was determined after extensive discussions at an Ovarian Cancer Action meeting in January 2015.

Rethinking ovarian cancer II: reducing mortality from high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) accounts for 70-80% of ovarian cancer deaths, and overall survival has not changed significantly for several decades. In this Opinion article, we outline a set of research priorities that we believe will reduce incidence and improve outcomes for women with this disease. This 'roadmap' for HGSOC was determined after extensive discussions at an Ovarian Cancer Action meeting in January 2015.

Rethinking ovarian cancer II: reducing mortality from high-grade serous ovarian cancer

High-grade serous ovarian cancer (HGSOC) accounts for 70-80% of ovarian cancer deaths, and overall survival has not changed significantly for several decades. In this Opinion article, we outline a set of research priorities that we believe will reduce incidence and improve outcomes for women with this disease. This 'roadmap' for HGSOC was determined after extensive discussions at an Ovarian Cancer Action meeting in January 2015.

LRP1B deletion is associated with poor outcome for glioblastoma patients

INTRODUCTION

Deletion of the tumor suppressor gene LRP1B has been reported in glioblastoma, the most aggressive primary brain tumor in adults. Our objective was to analyze frequency and prognostic impact of LRP1B deletion and expression levels.

METHODS

We retrospectively included all the primary IDH1/2 wild-type GBM patients with available clinical follow-up, DNA and RNA from our database. Deletions were analyzed by SNP-array. LRP1B mRNA expression was analyzed by reverse transcription quantitative polymerase chain reaction.

RESULTS

178 patients were included with a median age of 62.36 years. LRP1B deletions were observed for 10.1% of patients (complete: 2.8%, partial: 7.3%). LRP1B deletions were associated with poor progression-free survival (PFS) (p=0.004) and overall survival (OS) (p=0.001). By multivariate analysis, LRP1B deletions remained significant for both PFS (p=0.003, hazard ratio (HR): 2.261) and OS (p=0.001, HR: 2.609). LRP1B was down expressed with a mean relative expression of 46% comparatively to normal tissue. No association between LRP1B mRNA and patient outcome was observed. No correlation was found between the deletions and the mRNA down-expression. These results were validated using GBM TCGA data.

CONCLUSION

LRP1B presents with frequent molecular alterations which impact patient outcome, highlighting the potential interest of this gene for glioblastoma patients.

Whole-genome characterization of chemoresistant ovarian cancer

Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.

Whole-genome characterization of chemoresistant ovarian cancer

Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.

Whole-genome characterization of chemoresistant ovarian cancer

Patients with high-grade serous ovarian cancer (HGSC) have experienced little improvement in overall survival, and standard treatment has not advanced beyond platinum-based combination chemotherapy, during the past 30 years. To understand the drivers of clinical phenotypes better, here we use whole-genome sequencing of tumour and germline DNA samples from 92 patients with primary refractory, resistant, sensitive and matched acquired resistant disease. We show that gene breakage commonly inactivates the tumour suppressors RB1, NF1, RAD51B and PTEN in HGSC, and contributes to acquired chemotherapy resistance. CCNE1 amplification was common in primary resistant and refractory disease. We observed several molecular events associated with acquired resistance, including multiple independent reversions of germline BRCA1 or BRCA2 mutations in individual patients, loss of BRCA1 promoter methylation, an alteration in molecular subtype, and recurrent promoter fusion associated with overexpression of the drug efflux pump MDR1.

Spatial and temporal heterogeneity in high-grade serous ovarian cancer: a phylogenetic analysis

BACKGROUND

The major clinical challenge in the treatment of high-grade serous ovarian cancer (HGSOC) is the development of progressive resistance to platinum-based chemotherapy. The objective of this study was to determine whether intra-tumour genetic heterogeneity resulting from clonal evolution and the emergence of subclonal tumour populations in HGSOC was associated with the development of resistant disease.

METHODS AND FINDINGS

Evolutionary inference and phylogenetic quantification of heterogeneity was performed using the MEDICC algorithm on high-resolution whole genome copy number profiles and selected genome-wide sequencing of 135 spatially and temporally separated samples from 14 patients with HGSOC who received platinum-based chemotherapy. Samples were obtained from the clinical CTCR-OV03/04 studies, and patients were enrolled between 20 July 2007 and 22 October 2009. Median follow-up of the cohort was 31 mo (interquartile range 22-46 mo), censored after 26 October 2013. Outcome measures were overall survival (OS) and progression-free survival (PFS). There were marked differences in the degree of clonal expansion (CE) between patients (median 0.74, interquartile range 0.66-1.15), and dichotimization by median CE showed worse survival in CE-high cases (PFS 12.7 versus 10.1 mo, p = 0.009; OS 42.6 versus 23.5 mo, p = 0.003). Bootstrap analysis with resampling showed that the 95% confidence intervals for the hazard ratios for PFS and OS in the CE-high group were greater than 1.0. These data support a relationship between heterogeneity and survival but do not precisely determine its effect size. Relapsed tissue was available for two patients in the CE-high group, and phylogenetic analysis showed that the prevalent clonal population at clinical recurrence arose from early divergence events. A subclonal population marked by a NF1 deletion showed a progressive increase in tumour allele fraction during chemotherapy.

CONCLUSIONS

This study demonstrates that quantitative measures of intra-tumour heterogeneity may have predictive value for survival after chemotherapy treatment in HGSOC. Subclonal tumour populations are present in pre-treatment biopsies in HGSOC and can undergo expansion during chemotherapy, causing clinical relapse.

WWOX, large common fragile site genes, and cancer

WWOX is a gene that spans an extremely large chromosomal region. It is derived from within chromosomal band 16q23.2 which is a region with frequent deletions and other alterations in a variety of different cancers. This chromosomal band also contains the FRA16D common fragile site (CFS). CFSs are chromosomal regions found in all individuals which are highly unstable. WWOX has also been demonstrated to function as a tumor suppressor that is involved in the development of many cancers. Two other highly unstable CFSs, FRA3B (3p14.2) and FRA6E (6q26), also span extremely large genes, FHIT and PARK2, respectively, and these two genes are also found to be important tumor suppressors. There are a number of interesting similarities between these three large CFS genes. In spite of the fact that they are derived from some of the most unstable chromosomal regions in the genome, they are found to be highly evolutionarily conserved and the chromosomal region spanning the mouse homologs of both WWOX and FHIT are also CFSs in mice. Many of the other CFSs also span extremely large genes and many of these are very attractive tumor suppressor candidates. WWOX is therefore a member of a very interesting family of very large CFS genes.

Transposon mutagenesis identifies genes and evolutionary forces driving gastrointestinal tract tumor progression

To provide a more comprehensive understanding of the genes and evolutionary forces driving colorectal cancer (CRC) progression, we performed Sleeping Beauty (SB) transposon mutagenesis screens in mice carrying sensitizing mutations in genes that act at different stages of tumor progression. This approach allowed us to identify a set of genes that appear to be highly relevant for CRC and to provide a better understanding of the evolutionary forces and systems properties of CRC. We also identified six genes driving malignant tumor progression and a new human CRC tumor-suppressor gene, ZNF292, that might also function in other types of cancer. Our comprehensive CRC data set provides a resource with which to develop new therapies for treating CRC.

Very large common fragile site genes and their potential role in cancer development

Common fragile sites (CFSs) are large chromosomal regions that are hot-spots for alterations especially within cancer cells. The three most frequently expressed CFS regions (FRA3B, FRA16D and FRA6E) contain genes that span extremely large genomic regions (FHIT, WWOX and PARK2, respectively), and these genes were found to function as important tumor suppressors. Many other CFS regions contain extremely large genes that are also targets of alterations in multiple cancers, but none have yet been demonstrated to function as tumor suppressors. The loss of expression of just FHIT or WWOX has been found to be associated with a worse overall clinical outcome. Studies in different cancers have revealed that some cancers have decreased expression of multiple large CFS genes. This loss of expression could have a profound phenotypic effect on these cells. In this review, we will summarize the known large common fragile site genes and discuss their potential relationship to cancer development.

Harnessing the potential of lipid-based nanomedicines for type-specific ovarian cancer treatments

Epithelial ovarian cancers are a group of at least five histologically and clinically distinct diseases, yet at this time patients with these different diseases are all treated with the same platinum and taxane-based chemotherapeutic regimen. With increased knowledge of histotype-specific differences that correlate with treatment responses and resistance, novel treatment strategies will be developed for each distinct disease. Type-specific or resistance-driven molecularly targeted agents will provide some specificity over traditional chemotherapies and it is argued here that nanoscaled drug delivery systems, in particular lipid-based formulations, have the potential to improve the delivery and specificity of pathway-specific drugs and broad-spectrum cytotoxic chemotherapeutics. An overview of the current understanding of ovarian cancers and the evolving clinical management of these diseases is provided. This overview is needed as it provides the context for understanding the current role of drug delivery systems in the treatment of ovarian cancer and the need to design formulations for treatment of clinically distinct forms of ovarian cancer.

NCI Workshop Report: Clinical and Computational Requirements for Correlating Imaging Phenotypes with Genomics Signatures

The National Cancer Institute (NCI) Cancer Imaging Program organized two related workshops on June 26–27, 2013, entitled “Correlating Imaging Phenotypes with Genomics Signatures Research” and “Scalable Computational Resources as Required for Imaging-Genomics Decision Support Systems.” The first workshop focused on clinical and scientific requirements, exploring our knowledge of phenotypic characteristics of cancer biological properties to determine whether the field is sufficiently advanced to correlate with imaging phenotypes that underpin genomics and clinical outcomes, and exploring new scientific methods to extract phenotypic features from medical images and relate them to genomics analyses. The second workshop focused on computational methods that explore informatics and computational requirements to extract phenotypic features from medical images and relate them to genomics analyses and improve the accessibility and speed of dissemination of existing NIH resources. These workshops linked clinical and scientific requirements of currently known phenotypic and genotypic cancer biology characteristics with imaging phenotypes that underpin genomics and clinical outcomes. The group generated a set of recommendations to NCI leadership and the research community that encourage and support development of the emerging radiogenomics research field to address short-and longer-term goals in cancer research.

Somatic copy number alterations predict response to platinum therapy in epithelial ovarian cancer

OBJECTIVE

Platinum resistance remains an obstacle in the treatment of epithelial ovarian cancer (EOC). The goal of this study was to profile EOCs for somatic copy number alterations (SCNAs) as predictive markers of platinum response.

METHODS

SCNAs were assessed in a discovery (n=86) and validation cohort (n=115) of high risk stage I or stage II-IV EOCs using high-resolution SNP arrays. ASCAT and GISTIC identified all significantly overrepresented amplified or deleted chromosomal regions. Cox regression and univariate analysis assessed which SCNAs correlated with overall survival (OS), progression-free survival (PFS), platinum-free interval (PFI) and platinum response. Relevant SCNAs were also assessed in a pooled analysis involving both cohorts and published SCNA data from The Cancer Genome Atlas (TCGA; n=227).

RESULTS

We identified 53 regions to be significantly overrepresented in EOC. Of these, 6 were associated with OS, PFS or PFI in the discovery cohort at P<0.05. In the validation cohort, amplifications of chromosomal region 14q32.33, which contains AKT1 as a potential driver gene, also correlated with OS (OR=1.670; P=0.018). In a pooled analysis of 428 tumors, involving the discovery, validation and TCGA cohorts, 14q32.33 amplifications significantly reduced OS, PFS and PFI (HR=2.69, P=1.7×10(-4); HR=1.82, P=1.9×10(-2) and HR=1.80, P=2.2×10(-2) respectively). Moreover, AKT1 mRNA expression correlated with the number of chromosomal copies of the 14q32.33 region (P=2.8×10(-11);R(2)=0.26).

CONCLUSIONS

We established that amplifications in 14q32.33 were associated with reduced OS, PFS, PFI and platinum resistance in three independent cohorts, suggesting that AKT1 amplifications act as a potentially predictive marker for EOC treated with platinum-based chemotherapy.

Massively-parallel sequencing assists the diagnosis and guided treatment of cancers of unknown primary

The clinical management of patients with cancer of unknown primary (CUP) is hampered by the absence of a definitive site of origin. We explored the utility of massively-parallel (next-generation) sequencing for the diagnosis of a primary site of origin and for the identification of novel treatment options. DNA enrichment by hybridization capture of 701 genes of clinical and/or biological importance, followed by massively-parallel sequencing, was performed on 16 CUP patients who had defied attempts to identify a likely site of origin. We obtained high quality data from both fresh-frozen and formalin-fixed, paraffin-embedded samples, demonstrating accessibility to routine diagnostic material. DNA copy-number obtained by massively-parallel sequencing was comparable to that obtained using oligonucleotide microarrays or quantitatively hybridized fluorescently tagged oligonucleotides. Sequencing to an average depth of 458-fold enabled detection of somatically acquired single nucleotide mutations, insertions, deletions and copy-number changes, and measurement of allelic frequency. Common cancer-causing mutations were found in all cancers. Mutation profiling revealed therapeutic gene targets and pathways in 12/16 cases, providing novel treatment options. The presence of driver mutations that are enriched in certain known tumour types, together with mutational signatures indicative of exposure to sunlight or smoking, added to clinical, pathological, and molecular indicators of likely tissue of origin. Massively-parallel DNA sequencing can therefore provide comprehensive mutation, DNA copy-number, and mutational signature data that are of significant clinical value for a majority of CUP patients, providing both cumulative evidence for the diagnosis of primary site and options for future treatment.

Phylogenetic quantification of intra-tumour heterogeneity

Intra-tumour genetic heterogeneity is the result of ongoing evolutionary change within each cancer. The expansion of genetically distinct sub-clonal populations may explain the emergence of drug resistance, and if so, would have prognostic and predictive utility. However, methods for objectively quantifying tumour heterogeneity have been missing and are particularly difficult to establish in cancers where predominant copy number variation prevents accurate phylogenetic reconstruction owing to horizontal dependencies caused by long and cascading genomic rearrangements. To address these challenges, we present MEDICC, a method for phylogenetic reconstruction and heterogeneity quantification based on a Minimum Event Distance for Intra-tumour Copy-number Comparisons. Using a transducer-based pairwise comparison function, we determine optimal phasing of major and minor alleles, as well as evolutionary distances between samples, and are able to reconstruct ancestral genomes. Rigorous simulations and an extensive clinical study show the power of our method, which outperforms state-of-the-art competitors in reconstruction accuracy, and additionally allows unbiased numerical quantification of tumour heterogeneity. Accurate quantification and evolutionary inference are essential to understand the functional consequences of tumour heterogeneity. The MEDICC algorithms are independent of the experimental techniques used and are applicable to both next-generation sequencing and array CGH data.

Resistance to CDK2 inhibitors is associated with selection of polyploid cells in CCNE1-amplified ovarian cancer

PURPOSE

Amplification of cyclin E1 (CCNE1) is associated with poor outcome in breast, lung, and other solid cancers, and is the most prominent structural variant associated with primary treatment failure in high-grade serous ovarian cancer (HGSC). We have previously shown that CCNE1-amplified tumors show amplicon-dependent sensitivity to CCNE1 suppression. Here, we explore targeting CDK2 as a novel therapeutic strategy in CCNE1-amplified cancers and mechanisms of resistance.

EXPERIMENTAL DESIGN

We examined the effect of CDK2 suppression using RNA interference and small-molecule inhibitors in SK-OV-3, OVCAR-4, and OVCAR-3 ovarian cancer cell lines. To identify mechanisms of resistance, we derived multiple, independent resistant sublines of OVCAR-3 to CDK2 inhibitors. Resistant cells were extensively characterized by gene expression and copy number analysis, fluorescence-activated cell sorting profiling and conventional karyotyping. In addition, we explored the relationship between CCNE1 amplification and polyploidy using data from primary tumors.

RESULTS

We validate CDK2 as a therapeutic target in CCNE1-amplified cells by showing selective sensitivity to suppression, either by gene knockdown or using small-molecule inhibitors. In addition, we identified two resistance mechanisms, one involving upregulation of CDK2 and another novel mechanism involving selection of polyploid cells from the pretreatment tumor population. Our analysis of genomic data shows that polyploidy is a feature of cancer genomes with CCNE1 amplification.

CONCLUSIONS

These findings suggest that cyclinE1/CDK2 is an important therapeutic target in HGSC, but that resistance to CDK2 inhibitors may emerge due to upregulation of CDK2 target protein and through preexisting cellular polyploidy.

Distinct evolutionary trajectories of primary high-grade serous ovarian cancers revealed through spatial mutational profiling

High-grade serous ovarian cancer (HGSC) is characterized by poor outcome, often attributed to the emergence of treatment-resistant subclones. We sought to measure the degree of genomic diversity within primary, untreated HGSCs to examine the natural state of tumour evolution prior to therapy. We performed exome sequencing, copy number analysis, targeted amplicon deep sequencing and gene expression profiling on 31 spatially and temporally separated HGSC tumour specimens (six patients), including ovarian masses, distant metastases and fallopian tube lesions. We found widespread intratumoural variation in mutation, copy number and gene expression profiles, with key driver alterations in genes present in only a subset of samples (eg PIK3CA, CTNNB1, NF1). On average, only 51.5% of mutations were present in every sample of a given case (range 10.2-91.4%), with TP53 as the only somatic mutation consistently present in all samples. Complex segmental aneuploidies, such as whole-genome doubling, were present in a subset of samples from the same individual, with divergent copy number changes segregating independently of point mutation acquisition. Reconstruction of evolutionary histories showed one patient with mixed HGSC and endometrioid histology, with common aetiologic origin in the fallopian tube and subsequent selection of different driver mutations in the histologically distinct samples. In this patient, we observed mixed cell populations in the early fallopian tube lesion, indicating that diversity arises at early stages of tumourigenesis. Our results revealed that HGSCs exhibit highly individual evolutionary trajectories and diverse genomic tapestries prior to therapy, exposing an essential biological characteristic to inform future design of personalized therapeutic solutions and investigation of drug-resistance mechanisms.

The integrated landscape of driver genomic alterations in glioblastoma

Glioblastoma is one of the most challenging forms of cancer to treat. Here we describe a computational platform that integrates the analysis of copy number variations and somatic mutations and unravels the landscape of in-frame gene fusions in glioblastoma. We found mutations with loss of heterozygosity in LZTR1, encoding an adaptor of CUL3-containing E3 ligase complexes. Mutations and deletions disrupt LZTR1 function, which restrains the self renewal and growth of glioma spheres that retain stem cell features. Loss-of-function mutations in CTNND2 target a neural-specific gene and are associated with the transformation of glioma cells along the very aggressive mesenchymal phenotype. We also report recurrent translocations that fuse the coding sequence of EGFR to several partners, with EGFR-SEPT14 being the most frequent functional gene fusion in human glioblastoma. EGFR-SEPT14 fusions activate STAT3 signaling and confer mitogen independence and sensitivity to EGFR inhibition. These results provide insights into the pathogenesis of glioblastoma and highlight new targets for therapeutic intervention.

New horizons for lipoprotein receptors: communication by β-propellers

The lipoprotein receptor (LR) family constitutes a large group of structurally closely related receptors with broad ligand-binding specificity. Traditionally, ligand binding to LRs has been anticipated to involve merely the complement type repeat (CR)-domains omnipresent in the family. Recently, this dogma has transformed with the observation that β-propellers of some LRs actively engage in complex formation too. Based on an in-depth decomposition of current structures and sequences, we suggest that exploitation of the β-propellers as binding targets depends on receptor subgroups. In particular, we highlight the shutter mechanism of β-propellers as a general recognition motif for NxI-containing ligands, and we present indications that the generalized β-propeller-induced ligand release mechanism is not applicable for the larger LRs. For the giant LR members, we present evidence that their β-propellers may also actively engage in ligand binding. We therefore advocate for an increased focus on solving the structure-function relationship of this group of important biological receptors.

Integrated genomic characterization of endometrial carcinoma

We performed an integrated genomic, transcriptomic and proteomic characterization of 373 endometrial carcinomas using array- and sequencing-based technologies. Uterine serous tumours and ∼25% of high-grade endometrioid tumours had extensive copy number alterations, few DNA methylation changes, low oestrogen receptor/progesterone receptor levels, and frequent TP53 mutations. Most endometrioid tumours had few copy number alterations or TP53 mutations, but frequent mutations in PTEN, CTNNB1, PIK3CA, ARID1A and KRAS and novel mutations in the SWI/SNF chromatin remodelling complex gene ARID5B. A subset of endometrioid tumours that we identified had a markedly increased transversion mutation frequency and newly identified hotspot mutations in POLE. Our results classified endometrial cancers into four categories: POLE ultramutated, microsatellite instability hypermutated, copy-number low, and copy-number high. Uterine serous carcinomas share genomic features with ovarian serous and basal-like breast carcinomas. We demonstrated that the genomic features of endometrial carcinomas permit a reclassification that may affect post-surgical adjuvant treatment for women with aggressive tumours.

An integrative genomic analysis of several hundred endometrial carcinomas shows that a minority of tumour samples carry copy number alterations or TP53 mutations and many contain key cancer-related gene mutations, such as those involved in canonical pathways and chromatin remodelling; a reclassification of endometrial tumours into four distinct types is proposed, which may have an effect on patient treatment regimes.

This paper from The Cancer Genome Atlas Research Network presents an in-depth genome-wide analysis of endometrial (uterine) carcinomas from more than 350 patients. Based on a series of genomic features including newly identified hotspot mutations in the DNA polymerase gene POLE, and novel mutations in the ARID5B DNA-binding protein, the authors propose a reclassification of endometrial tumours into four distinct types. This might have clinical relevance for post-surgical adjuvant treatment of women with aggressive tumours.

Genome and transcriptome sequencing in prospective metastatic triple-negative breast cancer uncovers therapeutic vulnerabilities

Triple-negative breast cancer (TNBC) is characterized by the absence of expression of estrogen receptor, progesterone receptor, and HER-2. Thirty percent of patients recur after first-line treatment, and metastatic TNBC (mTNBC) has a poor prognosis with median survival of one year. Here, we present initial analyses of whole genome and transcriptome sequencing data from 14 prospective mTNBC. We have cataloged the collection of somatic genomic alterations in these advanced tumors, particularly those that may inform targeted therapies. Genes mutated in multiple tumors included TP53, LRP1B, HERC1, CDH5, RB1, and NF1. Notable genes involved in focal structural events were CTNNA1, PTEN, FBXW7, BRCA2, WT1, FGFR1, KRAS, HRAS, ARAF, BRAF, and PGCP. Homozygous deletion of CTNNA1 was detected in 2 of 6 African Americans. RNA sequencing revealed consistent overexpression of the FOXM1 gene when tumor gene expression was compared with nonmalignant breast samples. Using an outlier analysis of gene expression comparing one cancer with all the others, we detected expression patterns unique to each patient's tumor. Integrative DNA/RNA analysis provided evidence for deregulation of mutated genes, including the monoallelic expression of TP53 mutations. Finally, molecular alterations in several cancers supported targeted therapeutic intervention on clinical trials with known inhibitors, particularly for alterations in the RAS/RAF/MEK/ERK and PI3K/AKT/mTOR pathways. In conclusion, whole genome and transcriptome profiling of mTNBC have provided insights into somatic events occurring in this difficult to treat cancer. These genomic data have guided patients to investigational treatment trials and provide hypotheses for future trials in this irremediable cancer.