High-grade Serous Ovarian Cancer Tumors Research Articles

A single-cell landscape of high-grade serous ovarian cancer.

Malignant abdominal fluid (ascites) frequently develops in women with advanced high-grade serous ovarian cancer (HGSOC) and is associated with drug resistance and a poor prognosis1. To comprehensively characterize the HGSOC ascites ecosystem, we used single-cell RNA sequencing to profile ~11,000 cells from 22 ascites specimens from 11 patients with HGSOC. We found significant inter-patient variability in the composition and functional programs of ascites cells, including immunomodulatory fibroblast sub-populations and dichotomous macrophage populations. We found that the previously described immunoreactive and mesenchymal subtypes of HGSOC, which have prognostic implications, reflect the abundance of immune infiltrates and fibroblasts rather than distinct subsets of malignant cells2. Malignant cell variability was partly explained by heterogeneous copy number alteration patterns or expression of a stemness program. Malignant cells shared expression of inflammatory programs that were largely recapitulated in single-cell RNA sequencing of ~35,000 cells from additionally collected samples, including three ascites, two primary HGSOC tumors and three patient ascites-derived xenograft models. Inhibition of the JAK/STAT pathway, which was expressed in both malignant cells and cancer-associated fibroblasts, had potent anti-tumor activity in primary short-term cultures and patient-derived xenograft models. Our work contributes to resolving the HSGOC landscape3-5 and provides a resource for the development of novel therapeutic approaches.

Unraveling tumor-immune heterogeneity in advanced ovarian cancer uncovers immunogenic effect of chemotherapy.

In metastatic cancer, the degree of heterogeneity of the tumor microenvironment (TME) and its molecular underpinnings remain largely unstudied. To characterize the tumor-immune interface at baseline and during neoadjuvant chemotherapy (NACT) in high-grade serous ovarian cancer (HGSOC), we performed immunogenomic analysis of treatment-naive and paired samples from before and after treatment with chemotherapy. In treatment-naive HGSOC, we found that immune-cell-excluded and inflammatory microenvironments coexist within the same individuals and within the same tumor sites, indicating ubiquitous variability in immune cell infiltration. Analysis of TME cell composition, DNA copy number, mutations and gene expression showed that immune cell exclusion was associated with amplification of Myc target genes and increased expression of canonical Wnt signaling in treatment-naive HGSOC. Following NACT, increased natural killer (NK) cell infiltration and oligoclonal expansion of T cells were detected. We demonstrate that the tumor-immune microenvironment of advanced HGSOC is intrinsically heterogeneous and that chemotherapy induces local immune activation, suggesting that chemotherapy can potentiate the immunogenicity of immune-excluded HGSOC tumors.

Effect on response to neoadjuvant chemotherapy in high-grade serous ovarian cancer by inhibiting the GAS6/AXL pathway and inducing homologous recombination deficiency.

6080 Background: Less than 10% of patients with high grade serous ovarian cancer (HGSC) have a complete pathologic response to neoadjuvant chemotherapy. We aimed to identify a biomarker predictive of response to neoadjuvant chemotherapy and to determine if GAS6/AXL inhibition with AVB500 (AVB) could increase platinum response. Methods: AVB was supplied by Aravive Biologics. HGSC tumor samples were obtained pre- and post-neoadjuvant chemotherapy. GAS6 expression was measured by tissue immunohistochemistry (IHC) and serum ELISA. Four HGSC cell lines were used for all experiments. Immunofluorescent (IF) assays targeting ɣH2AX for DNA damage, RAD51, BRCA1, and BRCA2 for homologous recombination (HR) and 53BP1 for non-homologous end joining (NHEJ) were performed. Flow cytometry was used to evaluate RPA binding. DNA fiber assays were performed. In vitro clonogenic assays were done on chemoresistant ovarian tumor cells treated with carboplatin (carbo) +/- AVB and olaparib +/- AVB. Synergy assays were analyzed using Combenefit software. Mouse models were used to evaluate the combination of carboplatin + AVB and olaparib + AVB on tumor burden. Results: Patients with high pretreatment tumor GAS6 IHC expression ( > 85%) or serum GAS6 concentrations ( > 25ng/mL) were more likely to have a poor response to neoadjuvant chemotherapy than those with low GAS6 (P = 0.002). Additionally, high GAS6 concentration was associated with decreased overall survival (24.4 months versus undefined, P = 0.009). Carbo + AVB resulted in decreased clonogenic colonies compared to carbo alone (p < 0.05). In vivo tumor mouse models treated with chemotherapy + AVB had significantly less tumor burden than those treated with chemotherapy alone (50mg vs 357mg, P = 0.003). We identified an induction in HR deficiency by a decrease in RAD51, BRCA1, and BRCA2 foci and RPA binding in cells treated with carbo + AVB compared to carbo (P < 0.05). There was increase in ɣH2AX and 53BP1 foci as well as replication fork slowing in tumor cells treated with carboplatin + AVB (P < 0.01). We also AVB and carboplatin were synergistic. Olaparib + AVB resulted in decreased clonogenic colonies (P < 0.05) and decreased tumor burden in mouse models (76mg vs 171mg, P = 0.03) compared to olaparib alone. Conclusions: GAS6 is a potential biomarker predictive of poor response to neoadjuvant chemotherapy in HGSC. Inhibition of this GAS6/AXL pathway with AVB improves sensitivity to traditional neoadjuvant chemotherapy by inducing a homologous recombination deficiency.

Tumor specific methylome in Chinese high-grade serous ovarian cancer characterized by gene expression profile and tumor genotype

ObjectiveExtensive genetic and limited epigenetics have been characterized by the Cancer Genome Atlas (TCGA) among Western High-grade serous ovarian cancer (HGSOC). The present study aimed to characterize Chinese HGSOC at genome scale. MethodsWe used reduced representation bisulfite sequencing to investigate whole-genome and tumor-specific DNA methylation in 21 HGSOC tumors paired with their normal tissues, followed by a replication study involving additional 41 HGSOC patients. Altered methylation patterns in HGSOC were further characterized by gene expression profiles and whole-exome sequencing data. ResultsComparing HGSOC tumors with normal tissues we observed global hypomethylation but with more specific hypermethylation in gene promoter. Totally, we revealed 159,881 differentially methylated regions (DMRs) and 4060 differentially expressed genes (DEGs). By integrating DNA methylation and mRNA expression data, we identified 153 negative (mainly in the upstream region) and 115 positive (mainly in the CDS regions) DMRs-DEGs correlated pairs, respectively. The negatively correlated DMRs-DEGs underlined Wnt and cell adhesion molecule binding as critical canonical pathways disrupted by DNA methylation. Eleven DMRs (in CAPS, FZD7, CDKN2A, PON3, KLF4, etc.), accompanied with a global DNA methylation marker, were validated in the replication samples. Whole-exome sequencing presented a relatively less dominated TP53 mutation in Chinese HGSOC compared to TCGA dataset. Unsupervised analysis of the three-level omics data identified differential methylation and expression subgroups based on tumor genetics, one of which presented increased DNA methylation and significantly associated with TP53 mutation. ConclusionsOur individual and integrated analyses contribute details about the tissue-specific genetic and DNA methylation landscape of Chinese HGSOC.

CtBP determines ovarian cancer cell fate through repression of death receptors

C-terminal binding protein 2 (CtBP2) is elevated in epithelial ovarian cancer, especially in the aggressive and highly lethal subtype, high-grade serous ovarian cancer (HGSOC). However, whether HGSOC tumor progression is dependent on CtBP2 or its paralog CtBP1, is not well understood. Here we report that CtBP1/2 repress HGSOC cell apoptosis through silencing of death receptors (DRs) 4/5. CtBP1 or 2 knockdown upregulated DR4/5 expression, and triggered autonomous apoptosis via caspase 8 activation, but dependent on cell-type context. Activation of DR4/5 by CtBP1/2 loss also sensitized HGSOC cell susceptibility to the proapoptotic DR4/5 ligand TRAIL. Consistent with its function as transcription corepressor, CtBP1/2 bound to the promoter regions of DR4/5 and repressed DR4/5 expression, presumably through recruitment to a repressive transcription regulatory complex. We also found that CtBP1 and 2 were both required for repression of DR4/5. Collectively, this study identifies CtBP1 and 2 as potent repressors of DR4/5 expression and activity, and supports the targeting of CtBP as a promising therapeutic strategy for HGSOC.

Abstract A080: Olaparib and the ATR inhibitor AZD6738 in relapsed, refractory cancer patients with homologous recombination (HR) repair mutations – OLAPCO

Abstract Introduction: Olaparib is a PARP inhibitor (PARPi) that provides significant clinical benefit in several BRCA-mutant cancers, including ovarian, breast, pancreas and prostate. The benefit is reduced considerably in patients with multiple prior lines of therapy and olaparib resistance has no specific treatment. PARP inhibition results in replication stress (RS) due to unrepaired single strand DNA breaks (SSB) and PARP trapping in BRCA- and other HR repair-deficient tumors. ATR has critical roles in the cellular response to SSB and RS. This makes ATR inhibitors an attractive partner with olaparib, since ATR inhibition has the potential to reverse the two major mechanisms of PARP inhibitor resistance, including restored HR or stabilization of stalled replication forks. The OLAPCO trial (NCT02576444 clinicaltrials.gov) investigated. the combination of olaparib and AZD6738, an inhibitor of ATR, in relapsed, refractory cancer patients with tumors harboring HR repair mutations and in patients with BRCA-mutated PARPi pre-treated/resistant high-grade serous ovarian cancer (HGSOC). Methods: Patients with treatment-refractory, relapsed cancer were enrolled at 4 participating centers. Germline and somatic mutations had to be deleterious by COSMIC or ClinVar for eligibility. Performance status and organ function requirements were standard for early phase trials. Olaparib was given at 300 mg bid daily and AZD6738 at 160 mg daily days 1-7 in a 28-day cycle. Patients were treated until progression. Objective response was assessed by RECIST1.1 and toxicity was assessed by CTCAE4.0. Endpoints were confirmed complete [CR] or partial [PR] response rate and clinical benefit (CB) rate (response [PR] and stable disease [SD] for > 16 weeks). Results: We enrolled 24 patients; 17 (71%) females; median age 59 (36-78) years. Patients were heavily pretreated, with a median of 4 (0-10) prior regimens. Myelosuppression, especially anemia and thrombocytopenia, was the most frequent toxicity but no patient required discontinuation. Two patients required olaparib reductions for anemia. At the time of data cut-off, 20 patients are evaluable for response assessment. One of 5 patients with ATM mutations had a CR, 2 patients have CB ongoing at 12+ months. Of 7 patients with HGSOC resistant to platinum and PARP inhibitors (1-3 prior agents), 1 achieved a PR ( -90%), 3 had a best response of SD with regression < 30% (1 ongoing at 1 year) and 3 patients had progression (PD) as best response (Table 1). No other mutation or cancer type demonstrated objective response. Conclusions: The combination of olaparib and the ATR inhibitor AZD6738 demonstrated preliminary activity in patients with tumors harboring ATM mutations and in PARPi-resistant BRCA1/2-mutated HGSOC. Activity in ATM loss with an ATR inhibitor is consistent with the expected synthetic lethality of these interwoven DNA repair pathways. The encouraging data in HGSOC patients who have already progressed on a PARP inhibitor warrants additional study to further define the potential of this regimen to reverse PARPi resistance in BRCA-mutated HGSOC and other relevant solid tumors. The durability of responses in both groups (4 >1 year) is promising. Table 1MutationATMBRCA prostate pancreasBRCA Prior PARPi HGSOCCHEK2MUS81PALB2IDH and SDHD #5471142 CR1 PR0 1 SD > 4 mos213 11 PD 33112 Inevaluable110 11 Citation Format: Joseph Paul Eder, Davendra Sohal, Haider Mahdi, Khanh Do, Vicki Keedy, Navid Hafez, Deborah Doroshow, Manuel Avedissian, Peter Mortimer, Colin Glover, Patricia LoRusso, Juliane M Juergensmeier, Geoffrey I Shapiro. Olaparib and the ATR inhibitor AZD6738 in relapsed, refractory cancer patients with homologous recombination (HR) repair mutations – OLAPCO [abstract]. In: Proceedings of the AACR-NCI-EORTC International Conference on Molecular Targets and Cancer Therapeutics; 2019 Oct 26-30; Boston, MA. Philadelphia (PA): AACR; Mol Cancer Ther 2019;18(12 Suppl):Abstract nr A080. doi:10.1158/1535-7163.TARG-19-A080

Differential DNA methylation in high-grade serous ovarian cancer (HGSOC) is associated with tumor behavior

The epigenome offers an additional facet of cancer that can help categorize patients into those at risk of disease, recurrence, or treatment failure. We conducted a retrospective, nested, case-control study of advanced and recurrent high-grade serous ovarian cancer (HGSOC) patients in which we assessed epigenome-wide association using Illumina methylationEPIC arrays to characterize DNA methylation status and RNAseq to evaluate gene expression. Comparing HGSOC tumors with normal fallopian tube tissues we observe global hypomethylation but with skewing towards hypermethylation when interrogating gene promoters. In total, 5,852 gene interrogating probes revealed significantly different methylation. Within HGSOC, 57 probes highlighting 17 genes displayed significant differential DNA methylation between primary and recurrent disease. Between optimal vs suboptimal surgical outcomes 99 probes displayed significantly different methylation but only 29 genes showed an inverse correlation between methylation status and gene expression. Overall, differentially methylated genes point to several pathways including RAS as well as hippo signaling in normal vs primary HGSOC; valine, leucine, and isoleucine degradation and endocytosis in primary vs recurrent HGSOC; and pathways containing immune driver genes in optimal vs suboptimal surgical outcomes. Thus, differential DNA methylation identified numerous genes that could serve as potential biomarkers and/or therapeutic targets in HGSOC.

Tumor Specific Methylome in Chinese High-Grade Serous Ovarian Cancer Characterized by Gene Expression Profile and Tumor Genotype

Background: Extensive genetic and limited epigenetics have been characterized by the Cancer Genome Atlas (TCGA) among Western High-grade serous ovarian cancer (HGSOC). However, Chinese HGSOC has not been characterized at genome scale. Methods: We used reduced representation bisulfite sequencing (RRBS) to investigate the whole-genome and tumor-specific DNA methylation in 21 HGSOC paired with their non-neoplastic normal tissues, followed by a replication study involving another 41 pairs of HGSOC tumor and normal tissues. Altered methylation patterns in HGSOC were further characterized by gene expression profiles and whole-exome sequencing data. Findings: The comparisons between HGSOC and normals revealed 159,881 differentially methylated regions (DMRs) and 4,060 differentially expressed genes (DEGs). By integrating DNA methylation and mRNA expression data, we identified 153 (mainly in the upstream region) and 115 genes (mainly in the CDS regions) with negative and positive correlation, respectively. Subsequently, 11 DMRs, accompanied with a global DNA methylation marker (1ong interspersed nuclear elements 1, LINE-1), were selected and validated in the independent replication samples. Whole-exome sequencing presented a different mutational landscape in Chinese HGSOC compared to TCGA dataset, with a relatively dominated TP53 mutation (52.3% vs 96%) and a less-frequently mutated BRCA1/2 (4.7% vs 22%). Unsupervised analysis of the three-level omics data of HGSOC identified differential methylation and expression subgroups based on tumor genetics, one of which presented increased DNA methylation and significantly associated with TP53 mutation. Interpretation: Our individual and integrated analyses contribute details about the tissue-specific genetic and DNA methylation landscape of HGSOC. Funding Statement: This work was supported by the National Key Research and Development Program of China (grant number: 2016YFC1302703), the National Natural Science Foundation of China (81320108022, 81502877, and 81973113), the Program for Changjiang Scholars and Innovative Research Team in University (PCSIRT) in China (IRT_14R40), Tianjin Science and Technology Committee Foundation (16JCYBJC26600 and 18YFZCSY00520), the American Cancer Society Research Professor Award. Declaration of Interests: The authors declare that they have no competing interests. Ethics Approval Statement: The Ethics Committee of Tianjin Medical University Cancer Institute and Hospital approved the study protocol, and written informed consent was obtained from all patients. This procedure was conducted in accordance with the approved guidelines.

Abstract GMM-034: CO-REGULATION AND FUNCTIONAL COOPERATIVITY BETWEEN FOXM1 AND RHNO1 BIDIRECTIONAL GENES IN HIGH-GRADE SEROUS OVARIAN CANCER

Abstract PURPOSE: The FOXM1 transcription factor is canonically involved in cell cycle progression, but also promotes DNA repair and drug resistance, via its transcriptional activity. We previously reported that FOXM1 is located within the Ch.12p13.33 amplicon, which sustains copy number gains in ~60% of high-grade serous ovarian cancer (HGSC). More recently, we discovered that FOXM1 is arranged in a head-to-head configuration with RHNO1, a gene involved in the ATR/CHK1-dependent DNA replication stress (DRS) response. By virtue of its role in the DRS response, RHNO1 promotes homologous recombination (HR) DNA repair. We hypothesized that FOXM1 and RHNO1 are co-expressed in HGSC due to their bidirectional configuration, and that they functionally cooperate to promote HGSC cell survival, HR repair, and PARPi resistance. METHODS: We used 5' RACE, reporter constructs, and CRISPR-Cas9 (CRISPR) to characterize the FOXM1-RHNO1 bidirectional promoter. We correlated FOXM1 and RHNO1 mRNA expression and copy number in normal tissue and cancer data, including single cell RNA sequencing (scRNA-seq) of immortalized fallopian tube epithelial (FTE) cells and HGSC cells. We used RNAi and CRISPR to disrupt FOXM1 and/or RHNO1 in HGSC cells, and determined the resulting impact on gene expression, cell cycle, cell survival, HR repair, and olaparib (PARPi) sensitivity. RESULTS: FOXM1 and RHNO1 mRNA expression significantly correlated in normal tissues, including FTE, and in HGSC tumors and cell lines, both in bulk cells/tissues and at the single cell level. Co-expression appeared to result from the FOXM1-RHNO1 bidirectional promoter, which showed similar activity in each direction in cell models and correlated with endogenous mRNA expression. FOXM1 knockdown in HGSC cells led to enriched gene expression signatures for the G2/M checkpoint and reduced clonogenic survival. RHNO1 knockdown attenuated ATR/CHK1 signaling, reduced HR repair efficiency, and reduced HGSC clonogenic survival. Dual targeting of FOXM1 and RHNO1 using shRNA caused an additive effect on HR repair and clonogenic survival and caused synergistic sensitization of HGSC cells to olaparib treatment. Critically, bidirectional promoter targeting via a CRISPR-KRAB repressor recapitulated the effects of shRNA knockdown. Finally, FOXM1/RHNO1 bidirectional promoter repression led to olaparib sensitization in an in vitro HGSC model of acquired olaparib resistance. CONCLUSIONS: We demonstrate that FOXM1 and RHNO1 are frequently co-expressed in HGSC, most likely due to coordinated activity from their bidirectional promoter. Importantly, the FOXM1/RHNO1 bidirectional unit exhibits functional cooperativity for HR DNA repair and cell survival, and synergistically promotes olaparib resistance. Based on our data, we suggest that functionally interactive bidirectional gene modules are an under-appreciated oncogenic mechanism. Finally, we suggest that FOXM1 and RHNO1, or their associated pathways, are promising combinatorial therapeutic targets in HGSC. Citation Format: Carter J Barger, Linda Chee, Connor Branick, Kunle Odunsi, Lee Zou, Adam R. Karpf. CO-REGULATION AND FUNCTIONAL COOPERATIVITY BETWEEN FOXM1 AND RHNO1 BIDIRECTIONAL GENES IN HIGH-GRADE SEROUS OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr GMM-034.

Abstract NT-119: TARGET DISCOVERY OF NATURAL PRODUCT INSPIRED PHYLLANTHUSMINS FOR TREATMENT OF HIGH GRADE SEROUS OVARIAN CANCER

Abstract BACKGROUND: High grade serous ovarian cancer (HGSOC) is a lethal gynecological malignancy with a need for new therapeutic agents. Many of the most widely used chemotherapeutic drugs are either derived from or are semi-synthetic derivatives of natural products. We developed potent synthetic analogs (PHYs) of the phyllanthusmin class inspired by prior natural product isolated from Phyllanthus poilanei Beille. MATERIALS & METHODS: HGSOC cell lines, OVCAR3 and OVCAR8, and non-tumorigenic controls, IOSE80 and FT33, were used in this study. Cytotoxicity assays included sulforhodamine B assay, and annexin X/PI staining and Western blotting for confirmation of apoptosis induction. A photo affinity labeling method was used to attach PHY analogs to solid phase support. Targets were isolated using a pulldown technique and mass spectrometry. CRISPR-Cas9 genome editing was used to knockout and confirm putative targets. RESULTS: The most potent analog, PHY34, has nanomolar potency in HGSOC cell lines in vitro and displayed cytotoxic activity through late-stage autophagy inhibition and activation of apoptosis. PHY34 was readily bioavailable through intraperitoneal administration in vivo where it significantly reduced HGSOC tumor burden. Targets were identified using photo affinity labeling-aided protein pulldown and mass spectrometry, and confirmed by generating knockout cell lines of targets. CONCLUSIONS: This class of compounds holds promise as a potential, novel chemotherapeutic approach and demonstrates the effectiveness of pleiotropically targeting autophagy and apoptosis as a viable strategy for combating high grade serous ovarian cancer. Citation Format: Alexandria N. Young, Steven Kurina, Andrew Huntsman, Rathnayake A. Rathnayake, Melissa Korkmaz, A. Douglas Kinghorn, Leslie Aldrich, Stephanie Cologna, James R. Fuchs, Joanna E. Burdette. TARGET DISCOVERY OF NATURAL PRODUCT INSPIRED PHYLLANTHUSMINS FOR TREATMENT OF HIGH GRADE SEROUS OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr NT-119.

Abstract AP12: FOXM1 INDUCES DNA REPLICATION STRESS AND PROMOTES GENOMIC INSTABILITY DOWNSTREAM OF CYCLIN E1 IN HIGH-GRADE SEROUS OVARIAN CANCER

Abstract PURPOSE: Genomic instability (GI) is a hallmark of high-grade serous ovarian cancer (HGSC), and induction of the FOXM1 transcription factor regulatory network is the second most frequent genetic alteration in HGSC. FOXM1 expression is associated with cancer GI, but the mechanistic link is unknown. DNA replication stress (DRS), which involves altered replication fork dynamics, is a key contributor to cancer GI. FOXM1 and cyclin E1 (CCNE1) are both expressed in STIC lesions in the fallopian tube epithelium (FTE), and CCNE1-CDK2 enhances FOXM1 transcriptional activity. Based on these observations, we hypothesized that: 1) FOXM1 is linked to cancer GI through the induction of DRS, and 2) FOXM1 promotes GI downstream of CCNE1, by promoting unscheduled M phase entry in cells that have not completed DNA synthesis. METHODS: We determined associations between FOXM1 and markers of DRS and GI in TCGA HGSC data. We overexpressed FOXM1c and a DNA binding domain mutant (DBD) in immortalized FTE cells and characterized the impact on DRS, DNA replication, and DNA damage. We determined the impact of CCNE1 on FOXM1 expression in immortalized FTE cells. We determined the combined effect of CCNE1 and FOXM1 on GI in FTE cells. RESULTS: FOXM1 was significantly associated with markers of DRS (CHK1-Ser345) and GI (fractional copy number altered genome (CNA)) in TCGA HGSC data. FOXM1 expression, but not its DBD mutant, induced biomarkers of DRS and DNA damage in hTERT/mutant Tp53 immortalized FTE cells. Unexpectedly, FOXM1c increased DNA replication fork rate in FTE cells. Increased fork rate is a novel and recently recognized cause of DRS. CCNE1 expression in FTE cells induced and activated FOXM1, promoting mitotic entry. FOXM1 and CCNE1 co-expression in FTE cells induced an expression signature of GI, and TCGA HGSC tumors with FOXM1 and CCNE1 co-expression showed significantly increased GI. CONCLUSIONS: We demonstrate that FOXM1 induces DRS and DNA damage in FTE cells, providing an explanation for the known link between FOXM1 and GI. Notably, FOXM1 induces a novel form of DRS involving increased replication fork rate. We show that CCNE1 activates FOXM1, which in turn promotes mitotic entry and GI. These data reveal a potentially major form of oncogenic collaboration in HGSC, and has implications for HGSC treatment approaches that promote DRS or inhibit the cellular DRS response. . Citation Format: Carter J Barger, Kajal Biswas, Linda Chee, Ronny Drapkin, Shyam Sharan, Adam R. Karpf. FOXM1 INDUCES DNA REPLICATION STRESS AND PROMOTES GENOMIC INSTABILITY DOWNSTREAM OF CYCLIN E1 IN HIGH-GRADE SEROUS OVARIAN CANCER [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr AP12.

Engineered Adoptive T-cell Therapy Prolongs Survival in a Preclinical Model of Advanced-Stage Ovarian Cancer.

Adoptive T-cell therapy using high-affinity T-cell receptors (TCR) to target tumor antigens has potential for improving outcomes in high-grade serous ovarian cancer (HGSOC) patients. Ovarian tumors develop a hostile, multicomponent tumor microenvironment containing suppressive cells, inhibitory ligands, and soluble factors that facilitate evasion of antitumor immune responses. Developing and validating an immunocompetent mouse model of metastatic ovarian cancer that shares antigenic and immunosuppressive qualities of human disease would facilitate establishing effective T-cell therapies. We used deep transcriptome profiling and IHC analysis of human HGSOC tumors and disseminated mouse ID8VEGF tumors to compare immunologic features. We then evaluated the ability of CD8 T cells engineered to express a high-affinity TCR specific for mesothelin, an ovarian cancer antigen, to infiltrate advanced ID8VEGF murine ovarian tumors and control tumor growth. Human CD8 T cells engineered to target mesothelin were also evaluated for ability to kill HLA-A2+ HGSOC lines. IHC and gene-expression profiling revealed striking similarities between tumors of both species, including processing/presentation of a leading candidate target antigen, suppressive immune cell infiltration, and expression of molecules that inhibit T-cell function. Engineered T cells targeting mesothelin infiltrated mouse tumors but became progressively dysfunctional and failed to persist. Treatment with repeated doses of T cells maintained functional activity, significantly prolonging survival of mice harboring late-stage disease at treatment onset. Human CD8 T cells engineered to target mesothelin were tumoricidal for three HGSOC lines. Treatment with engineered T cells may have clinical applicability in patients with advanced-stage HGSOC.

The clinical significance and biological function of lncRNA SOCAR in serous ovarian carcinoma

BackgroundOvarian cancer (OvCa) is one of the most lethal gynecologic malignancies worldwide. Pelvic and abdominal metastasis is a leading cause for the poor prognosis of OvCa patients. The relationship between long non-coding RNAs (lncRNAs) and OvCa remains unclear. Identifying key lncRNAs related with OvCa metastasis is crucial for research on the mechanism of OvCa metastasis. This study was designed to investigate the role of a novel lncRNA, which we named SOCAR, in serous OvCa. MethodsLncRNA microarray and Real-time PCR were used to examine SOCAR expression in high grade serous ovarian cancer (HGSOC) and normal ovary tissues. The proliferation, migration and invasion of OvCa cell lines SKOV-3 and OVCAR-3 were analyzed by CCK-8, Transwell and Scratch wound healing assays. Western blotting was used to detect the expression of Wnt/β-catenin pathway-related proteins. ResultsA novel serous OvCa-related lncRNA, SOCAR, was identified via microarray. SOCAR was overexpressed in primary HGSOC tumors compared with normal ovary tissues, and the expression of SOCAR correlated with progression in HGSOC patients. SOCAR also had higher expression in metastatic HGSOC tissues compared with primary cancer tissues. Moreover, upregulation of SOCAR promoted proliferation, migration and invasion in OvCa cells. Expression of Wnt1, β-catenin and MMP-9 were all increased by SOCAR overexpression. ConclusionSOCAR is related with HGSOC oncogenesis and progression. It may promote proliferation, migration and invasion in OvCa cells partially by upregulating MMP-9 through the Wnt/β-catenin pathway.

Abstract 467: Deep single-cell RNA-seq of the putative cell of origin revealed a novel molecular subtype of high-grade serous ovarian cancer with poor prognosis

Abstract Accurate molecular classification in cancer is essential for rationalized therapy. However, achieving stable subtyping is highly challenging due to the underlying genomic complexity of tumors. An example of the most successful classification is in breast cancer where it is possible to link individual tumor types, basal vs luminal, to individual cell types of origin. However, the generalization of such an approach has not been easy because of the lack of knowledge about subtypes of the putative cells of origin. For instance, it has been difficult to establish a stable molecular classification of high-grade serous ovarian cancer (HGSOC). More recent evidence strongly supports the notion that HGSOC originates from the secretory cells in fallopian tube epithelium (FTE). However, whether or not there are multiple subtypes of secretory cells and how such subtypes are linked to tumor molecular subtypes have remained elusive. To address this issue, we applied single-cell RNA sequencing (Smart-Seq2) on around 4000 FTE cells from patients with ovarian or endometrial cancers. We developed and employed an in-house differential-expression-based clustering method, termed ClinCluster, for clinical samples that takes into account inter-patient variability. Apart from the established secretory and ciliated cell types, we discovered four novel subtypes of secretory cells and a rare intermediate cell type that co-expresses secretory and ciliated markers. We termed these four novel secretory subtypes as cell cycle, progenitor, epithelial-mesenchymal transition (EMT) and immunoreactive subtypes. Based on fifty-three biomarkers of these subtypes, we designed a panel of transcriptomic signatures and exploited them to deconvolute two bulk expression datasets of ovarian cancer: the RNA-seq dataset of TCGA (The Cancer Genome Atlas) and the microarray dataset of AOCS (Australian Ovarian Cancer Study). The deconvolution analysis revealed a poor-prognostic EMThigh subtype of HGSOC, which was not driven by copy number aberrations. Cox regression analysis indicated that the EMThigh tumors were strongly associated with poor overall survival in the two independent datasets tested (hazard ratio = 2.7, 95% confidence interval = 1.4 - 5.1, P = 0.002, n = 307 for TCGA; hazard ratio = 3.2, 95% confidence interval = 1.7 - 6.1, P = 0.0002, n = 253 for AOCS). Importantly, we found that the PI3K-Akt signaling pathway is upregulated in the EMThigh tumors (FDR < 0.002 for the two independent datasets) giving a strong potential for effective rationalized therapies. In summary, our work portrays a new model for the landscape of fallopian tube epithelium, the putative origin of HGSOC, and illustrates that the cellular subtypes in FTE are related to the HGSOC tumor types with important prognostic and therapeutic implications. Citation Format: Zhiyuan Hu, Abdulkhaliq Alsaadi, Nina Wietek, Laura Santana González, Christopher Yau, Ahmed Ashour Ahmed. Deep single-cell RNA-seq of the putative cell of origin revealed a novel molecular subtype of high-grade serous ovarian cancer with poor prognosis [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 467.

Ovarian cancer and the evolution of subtype classifications using transcriptional profiling†.

Ovarian cancer is a complex disease with multiple subtypes, each having distinct histopathologies and variable responses to treatment. This review highlights the technological milestones and the studies that have applied them to change our definitions of ovarian cancer. Over the past 50 years, technologies such as microarrays and next-generation sequencing have led to the discovery of molecular alterations that define each of the ovarian cancer subtypes and has enabled further subclassification of the most common subtype, high-grade serous ovarian cancer (HGSOC). Improvements in mutational profiling have provided valuable insight, such as the ubiquity of TP53 mutations in HGSOC tumors. However, the information derived from these technological advances has also revealed the immense heterogeneity of this disease, from variation between patients to compositional differences within single masses. In looking forward, the emerging technologies for single-cell and spatially resolved transcriptomics will allow us to better understand the cellular composition and structure of tumors and how these contribute to the molecular subtypes. Attempts to incorporate the complexities ovarian cancer has resulted in increasing sophistication of model systems, and the increased precision in molecular profiling of ovarian cancers has already led to the introduction of inhibitors of poly (ADP-ribose) polymerases as a new class of treatments for ovarian cancer with DNA repair deficiencies. Future endeavors to define increasingly accurate classification strategies for ovarian cancer subtypes will allow for confident prediction of disease progression and provide important insight into potentially targetable molecular mechanisms specific to each subtype.

Abstract B36: FOXM1 induces DNA replication stress, and its bidirectional gene partner RHNO1 participates in the DNA replication stress response, in high-grade serous ovarian cancer

Abstract Purpose: FOXM1 is located at 12p13.33, which shows copy number gains in the majority of high-grade serous ovarian cancer (HGSC) cases. The 12p13.33 amplicon contains 33 genes, some of which may cooperate with FOXM1 to exert oncogenic function. Although FOXM1 overexpression is associated with genomic instability in cancer, whether FOXM1 contributes directly to this phenotype is unclear. We hypothesized that FOXM1 induces DNA replication stress (DRS), resulting in ATR-CHK1 activation. Intriguingly, we noted that RHNO1, a component of the 9-1-1 complex required for ATR-CHK1 activation, is contained within the 12p13.33 amplicon and is arranged in a head-to-head orientation with FOXM1. Here, we characterized the FOXM1/RHNO1 bidirectional promoter, FOXM1/RHNO1 expression, and determined the role of FOXM1/RHNO1 in DRS, the DRS response, and clonogenic growth of HGSC cells. Methods: We used reporter assays to characterize the FOXM1/RHNO1 bidirectional promoter and FOXM1 transcriptional activity. We analyzed copy number, mRNA, and protein expression datasets in TCGA, CCLE, and GTEX. We measured FOXM1/RHNO1 expression in HGSC cell lines and tumors. We overexpressed FOXM1 in human immortalized fallopian tube epithelial (FTE) cells to determine its contribution to DRS and DNA damage. We knocked down RHNO1 in HGSC cells to determine its contribution to the DRS response and clonogenic growth. We performed Western blot analyses to measure markers of DRS and DNA damage. We characterized FOXM1-induced DNA damage at single-cell resolution using Comet assays and flow cytometry measurement of γ-H2AX. Results: FOXM1/RHNO1 showed copy number gains or amplifications in 58% of TCGA HGSC tumors, and FOXM1/RHNO1 mRNA expression significantly correlated in TCGA HGSC tumors, CCLE HGSC lines, and GTEX normal tissues. The FOXM1/RHNO1 bidirectional promoter showed balanced activity in each direction in FTE and HGSC cells, and bidirectional promoter activity correlated with endogenous mRNA expression. TCGA HGSC data indicated that FOXM1 expression associates with markers of DNA replication, global copy number alterations, and CHK1-Ser345-P, a canonical marker of DRS. In agreement, FOXM1 overexpression in FTE cells induced phosphorylation of ATR-Thr1989, CHK1-Ser317/345, H2AX-Ser139, and the proportion of DNA in Comet tails. In contrast, a DNA-binding domain mutant of FOXM1 did not induce DRS or DNA damage. RHNO1 knockdown attenuated CHK1-Ser345-P in response to DRS and RHNO1 shRNA knockdown or CRISPR-Cas9 knockout severely reduced HGSC cell clonogenic growth. Importantly, the effects of RHNO1 disruption were rescued by WT RHNO1 expression, but not by a RHNO1 mutant defective for interaction with the 9-1-1 complex. Conclusion: Our data reveal that FOXM1/RHNO1 share a bidirectional promoter and that this may account for their frequent coexpression in HGSC. FOXM1 induces DRS, and this is dependent on its ability to bind DNA. Conversely, RHNO1 contributes to ATR-CHK1 signaling and promotes the clonogenic growth of HGSC cells. We hypothesize that balanced FOXM1/RHNO1 expression promotes HGSC development and progression. Ongoing studies are characterizing the impact of FOXM1/RHNO1 on DRS and genomic instability in model systems. Finally, our data suggest that the ATR-CHK1 pathway is a synthetic lethal vulnerability in HGSC tumors that overexpress FOXM1. Citation Format: Carter J. Barger, Linda Chee, Connor Branick, Kunle Odunsi, Ronny Drapkin, Adam R. Karpf. FOXM1 induces DNA replication stress, and its bidirectional gene partner RHNO1 participates in the DNA replication stress response, in high-grade serous ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B36.

Abstract B70: Mathematical model quantifies the effect of novel combination therapies in high-grade serous ovarian cancer

Abstract Purpose: We introduce here the most comprehensive mathematical model to date for high-grade serous ovarian cancer patient treatment response and use it to predict the effect of novel combination therapies. Introduction: Platinum-based chemotherapy constitutes the backbone for clinical care of advanced solid cancers, such as high-grade serous ovarian cancer (HGSOC). The vast majority of patients, however, become resistant to platinum, which eventually leads to generally fatal refractory disease. As HGSOC tumors are heterogeneous, cancer cells often have activated many resistant mechanisms, and targeting a single mechanism at a time is unlikely to result in significant improvement in survival rates. A systems biology approach, where resistance mechanisms are comprehensively considered, is required in efforts to overcome platinum resistance. Methods: Platinum resistance is a multifactorial process and the most important resistance mechanisms are: 1) reduced intake or increased efflux leading to reduced platinum bioavailability in a cell, 2) DNA repair mechanisms that overcome platinum-induced DNA adducts, and 3) dysfunctional apoptosis machinery. The herein established mathematical model is based on three major resistance mechanisms and it models tumor growth and evolution as a deterministic continuous time, multitype branching process. Importantly, we have used comprehensive pre- and postoperative clinical data, including high-resolution 18F-fluorodeoxyglucose positron emission tomography/computed tomography images, from a HGSOC patient cohort. This allows accurate calibration of the model parameters, which ensures that the model is able to capture clinical course of HGSOC patients. In addition to quantifying the effect of a platinum-taxane to tumor burden of an HGSOC patient, we have modeled the impact of debulking surgery. This enables us to use the mathematical model in simulating “virtual HGSOC patients” who undergo standard-of-care (SOC) therapy, i.e., debulking surgery and platinum-taxane therapy. Results: Our model-generated virtual patients show almost identical treatment responses with two validation HGSOC cohorts that together contain data from 105 HGSOC patients. The average virtual HGSOC patient has platinum-free interval (PFI) of six months, which is identical to the mean PFI in the training and independent validation cohorts. The ability to create in silico HGSOC patients whose responses correspond to real-life HGSOC cohorts was supported statistically by the Kolmogorov-Smirnov test. As our model can capture the heterogeneous responses of individual HGSOC patients, we utilized it to evaluate the added value of combining novel targeted therapies to the current first-line SOC therapy. The results from the virtual clinical trials with selected targeted agents are in line with the results from early-phase clinical trials and pinpoint the most effective combination strategies. Further, our results show that targeting the three most important platinum-resistant mechanisms simultaneously with clinically available agents provides a significant survival advance to HGSOC patients. Conclusions: High failure rate in translating preclinical results to successful clinical trials is a major issue in oncology. The herein introduced mathematical framework enables creating virtual patient cohorts that capture the response variation in real-life patient cohorts. This allows for rapid and reliable estimate of the added value of the novel therapy in comparison to SOC therapy to optimize clinical trial design. Here we focused on overcoming platinum resistance in HGSOC and our results show substantial added value of combining three early-phase clinical trial agents, which target the three major resistant mechanisms and have been individually combined with SOC. Citation Format: Sampsa Hautaniemi, Emilia Kozlowska, Anniina Färkkilä, Tuulia Vallius, Olli Carpen, Seija Grenman, Rainer Lehtonen, Johanna Hynninen, Sakari Hietanen. Mathematical model quantifies the effect of novel combination therapies in high-grade serous ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B70.

Abstract B35: Australian Ovarian Cancer Assortment Trial–Allocating ovarian cancer patients into clinical trials based on molecular profiling

Abstract Background: The Australian Ovarian Cancer Assortment Trial (ALLOCATE) was designed as a pilot study to demonstrate feasibility of molecularly profiling patients with recurrent ovarian cancer with the aim of allocating patients to targeted therapies based on the genomic profile of their tumors. Materials and Methods: Two next-generation sequencing (NGS) panels, as well as a BRCA1 methylation assay, were used for molecular profiling of most common subtypes of ovarian cancer. A custom Illumina TruSeq Amplicon Low Input (v2) panel with dual-strand coverage was designed to target 38 genes commonly mutated and clinically important in ovarian cancer. The second assay was a NGS modification of the Multiplex Ligation-dependent Probe Amplification (MLPA) assay that was designed to target 11 genes with common copy number alterations (CNA) in ovarian cancer, including extensive BRCA1/2 coverage for large exonic deletions (Kondrashova et al., 2015). A thorough analytic validation was performed to ensure that both tests were fit for diagnostic use. Patients with recurrent epithelial ovarian cancer were eligible for the study. Where feasible, patients underwent biopsies of recurrent tumor that were snap frozen. Otherwise, archival FFPE tumor blocks were retrieved. Sequencing was performed using Illumina Miseq and HiSeq 2500 with target median coverage of 2000x (amplicon panel) and 800x (MLPA-Seq). Data were analyzed using an internally built pipeline, an upgraded version of AmpliVar (Hsu et al 2015), with Variant Effect Predictor (Mclaren et al., 2016) used for variant annotation. Results: Between December 2013 and October 2016, 113 patients with recurrent ovarian cancer were recruited from two tertiary hospitals, with 15 cases (13%) excluded due to insufficient tumor material or poor-quality DNA. Ninety-eight cases (87%) were analyzed and reports issued back to the referring clinician. Fifty-six patients (61%) in the study had recurrent high-grade serous ovarian cancer (HGSC). Of these, TP53 mutations were identified in 91%. Events in genes other than TP53 were detected in 44 cases, most commonly MYC and CCNE1 amplifications and BRCA1/2 mutations. BRCA1/2 reversions were identified in two cases, explaining their lack of response to platinum/PARPi. Fifteen patients (16%) had recurrent low-grade serous ovarian cancer (LGSC), with KRAS or BRAF mutations identified in four cases. Two HGSC tumors were reclassified as LGSC on the basis of a lack of TP53 mutation, presence of KRAS mutation, and subsequent pathology review. Other cases in the study included mucinous, clear cell, and mixed-histology carcinomas and a metastatic carcinosarcoma. In terms of clinical utility, 6 patients (7%) received a matched therapy. Three HGSC patients with somatic BRCA1/2 mutations were treated with PARP inhibitors. Another HGSC patient with ERBB2 amplification was treated with trastuzumab. One LGSC patient with a BRAF mutation was enrolled on a BRAF inhibitor clinical trial. A second LGSC patient was enrolled in a trial of anastrazole. Furthermore, 7 patients (14%) with HGSC who were previously untested were found to have a germline BRCA1/2 mutation and were subsequently referred to a familial cancer clinic for further management and cascade testing. The limitations in the study included the turnaround time and advanced stage of disease at enrolment, which significantly affected the clinical utility of the test. Conclusion: We demonstrated that molecular profiling of recurrent ovarian cancer using the ALLOCATE panel was feasible and reflected the known genomic characteristics of the different subtypes. However, challenges remain, including appropriate patient selection and efficient turnaround time for reporting. Furthermore, improved access to targeted therapies or clinical trials will also enhance the clinical utility of the ALLOCATE panel. Citation Format: Olga Kondrashova, George Au-Yeung, Leakhena Leas, Gwo-Yaw Ho, Sebastian Lunke, Kathryn Alsop, Clare Scott, Anne Hamilton, Sumitra Ananda, Alison Freimund, Michael Quinn, Orla McNally, Nadia Traficante, Tiffany Cowie, Matthew Wakefield, Arthur Hsu, Alex Dobrovic, Michael Christie, Graham Taylor, David Bowtell, Linda Mileshkin, Paul Waring. Australian Ovarian Cancer Assortment Trial–Allocating ovarian cancer patients into clinical trials based on molecular profiling. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr B35.

Abstract A14: TP53 missense mutations associate with different metabolic pathways

Abstract Background: Deleterious TP53 mutations are found in 99% of patients with high-grade serous ovarian cancer (HGSOC). TP53 missense mutations, found in two-thirds of HGSOC tumors, endow the mutant protein with new gain-of-function (GOF) activities leading to altered expression of genes involved in maintaining controlled cellular metabolism and the development of drug resistance. Identification of specific altered pathways could be exploited therapeutically. We investigated whether all missense mutations alter the same metabolic pathways. Methods: We used publicly available data from The Cancer Genome Atlas (TCGA) and the Australia Ovarian Cancer Study (AOCS). TCGA and AOCS gene expression datasets were downloaded from the Curated Ovarian Data, a resource of uniformly prepared microarray data from 23 studies with curated and documented clinical metadata. We merged gene expression data from TCGA (Affymetrix HT_HG-U133A) and AOCS (Affymetrix HG-U133Plus2), subset to 12,211 features common to both datasets and included non-missing values of invasive HGSOC. TP53 mutations were downloaded from TCGA and obtained for AOCS and merged with the curated datasets. The final datasets consisted of 295 patients in TCGA (N=184 with missense mutations with putative GOF activity, and N=111 nonsense mutations with putative loss of function (LOF) activity and 21 wild-type) and 142 patients in AOCS (N=83 missense mutations with putative GOF activity, N=59 nonsense mutations with putative LOF activity and N=13 wild-type). Gene expression values were normalized in each dataset separately by subtracting the mean value of each gene and dividing by the standard deviation. Mutations were categorized according to missense vs nonsense mutation class and also according to specific mutations. We evaluated all gene sets in KEGG but focused a priori on the association of Oxidative Phosphorylation (OXPHOS), Fatty Acid Metabolism (FA), Glycolysis and Gluconeogenesis (GLY), and the P53 pathway with overall (OS) and progression-free survival (PFS) using Cox regression models stratified by mutation class and adjusted for age and stage. Results: There were no significant differences between TP53 missense vs nonsense mutation class for gene set expressions for a priori pathways of interest in TCGA, and a nominal difference for the P53 gene set expression (P=0.07) in AOCS. Comparing TCGA, AOCS, and the combined datasets, differential gene set expressions by TP53 mutation class were observed in all three datasets at P<0.10 for the sulfur relay system, melanogenesis, peroxisome, and purine metabolism pathways. In AOCS among patients with missense, but not nonsense, mutations, FA gene set expression (P=0.06) was associated with PFS, and FA (P=0.03) and P53 (P=0.09) gene set expressions were associated with OS. No significant associations were observed in TCGA or after combining datasets. When categorized according to specific TP53 mutations, we observed significant differences in gene set expressions. Compared to nonsense mutations, TP53 mutations p.I195N or p.I195T were associated with differentially expressed genes in the GLY pathway (P=0.04) and TP53 mutations p.Y220C or p.Y220H (P=0.01) as well as p.R248G, p.R248Q or p.R248W (P=0.04) were associated with differentially expressed genes in the P53 pathway. Compared with survival among patients with nonsense mutations (median 43.4 months, range 0.3-116 months), patients with p.I195 mutations had OS of 47.7 months (range 3-64 months), patients with Y220 mutations had OS of 37.5 months (range 5-69 months) and patients with p.R248 mutations had OS of 33.6 months (range 0.8-59). Patients with the longest median OS of 84.1 months (range 1-180 months) had mutations p.R273C, p.R273C/R248Q combined, p.R273H, p.R273H/R248Q combined, p.R273L, or p.R273P. Conclusions: Specific TP53 missense mutations are associated with different metabolic pathways and may lead to differences in survival. Citation Format: Linda E. Kelemen, James D. Brenton, David D. Bowtell, Brooke L. Fridley. TP53 missense mutations associate with different metabolic pathways. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A14.

Abstract IA27: Functional genetic architecture of serous ovarian cancer

Abstract The degree of genetic aberrations characteristic of high-grade serous ovarian cancer (HGSC) makes identification of the molecular features that drive tumor progression difficult. Here, we perform genome-wide RNAi screens and whole-kinome proteomics to identify genes that are critical to their survival. We report that the tetraspanin CD151 contributes to survival of a subset of HGSC cell lines associated with a ZEB transcriptional program and supports the growth of HGSC tumors. Moreover, we show that high CD151 expression is prognostic of poor clinical outcome. We have identified essential kinases that manage biosynthetic stress indicative of the ovarian cancer transformed state. These data suggest that targeting pathways that underlie adaptation to cellular stress states rather than driver oncogenes may provide new therapeutic avenues for treating HGSC. Citation Format: Kyle Francis, Helen Burston, Daphna Mokady, Melany Wagner, Mauricio Medrano, Robert Rottapel. Functional genetic architecture of serous ovarian cancer. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr IA27.