Ovarian Cancer Histotypes Research Articles

Genomic and TCR profiling data reveal the distinct molecular traits in epithelial ovarian cancer histotypes.

Epithelial ovarian cancer (EOC) is classified into five major histotypes: high-grade serous (HGSOC), low-grade serous (LGSOC), clear cell (CCOC), endometrioid (ENOC), and mucinous (MOC). However, the landscape of molecular and immunological alterations in these histotypes, especially LGSOC, CCOC, ENOC, and MOC, is largely uncharacterized. We collected 101 treatment-naive EOC patients. The resected tumor tissues and paired preoperative peripheral blood samples were collected and subjected to target sequencing of 1021 cancer-associated genes and T cell repertoire sequencing. Distinct characteristics of mutations were identified among the five histotypes. Furthermore, tumor mutation burden (TMB) was found to be higher in CCOC and ENOC, but lower in LGSOC and HGSOC. Alterations associated with DNA damage repair (DDR) pathways and homologous recombination deficiencies (HRD) were prevalent in five histotypes. CCOC demonstrated increased level of T cell clonality compared with HSGOC. Interestingly, the proportion of the 100 most common T cell clones was associated with TMB and tumor neoantigen burden in CCOC, highlighting more sensitive anti-tumor responses in this histotype, which was also evidenced by the enhanced convergent recombination of T cell clones. These findings shed light on the molecular traits of genomic alteration and T cell repertoire in the five major EOC histotypes and may help optimize clinical management of EOC with different histotypes.

A multi-level investigation of the genetic relationship between endometriosis and ovarian cancer histotypes

SummaryEndometriosis is associated with increased risk of epithelial ovarian cancers (EOCs). Using data from large endometriosis and EOC genome-wide association meta-analyses, we estimate the genetic correlation and evaluate the causal relationship between genetic liability to endometriosis and EOC histotypes, and identify shared susceptibility loci. We estimate a significant genetic correlation (rg) between endometriosis and clear cell (rg = 0.71), endometrioid (rg = 0.48), and high-grade serous (rg = 0.19) ovarian cancer, associations supported by Mendelian randomization analyses. Bivariate meta-analysis identified 28 loci associated with both endometriosis and EOC, including 19 with evidence for a shared underlying association signal. Differences in the shared risk suggest different underlying pathways may contribute to the relationship between endometriosis and the different histotypes. Functional annotation using transcriptomic and epigenomic profiles of relevant tissues/cells highlights several target genes. This comprehensive analysis reveals profound genetic overlap between endometriosis and EOC histotypes with valuable genomic targets for understanding the biological mechanisms linking the diseases.

Altered cervicovaginal microbiota in premenopausal ovarian cancer patients.

Nearly three hundred thousand female patients are diagnosed with ovarian cancer in the world annually, and this number shows an increasing trend. However, characteristic symptoms caused by ovarian cancer are so few that early diagnosis remains challenging, and an effective screening method has not yet been established. Here, we conducted a case-control study in Japan to analyze the association between cervicovaginal microbiome and ovarian cancer, using 16S rRNA amplicon sequencing. Analysis of DNA extracted from cervical smear samples revealed Lactobacillus-dominant and Lactobacillus-deficient, highly-diversified bacterial communities in premenopausal and postmenopausal healthy controls, respectively, as reported for vaginal microbiota previously. We found that cervicovaginal microbiota in ovarian cancer patients, regardless of their menopausal status, were frequently a diversified community and similar to those in healthy subjects at postmenopausal ages. The diverse microbiota was associated with the major histotypes of epithelial ovarian cancer, including serous ovarian cancer and ovarian clear cell cancer. The present study implies the potential of a cervicovaginal microbiome biomarker in screening ovarian cancer in premenopausal women.

Abstract PO-232: Racial differences in the tumor immune landscape and survival of high-grade serous ovarian carcinoma

Abstract A survival benefit has been consistently observed for tumor infiltrating lymphocytes (TILs) among ovarian cancer patients; however, prior studies consist of predominantly white women and little work has been conducted in racially diverse cohorts. Here, we investigate racial differences in the tumor immune landscape and survival among African-American (AA) and white women with high-grade serous ovarian carcinoma (HGSOC), the most common histotype of ovarian cancer. Leveraging two population-based case-control studies of ovarian cancer, the African-American Cancer Epidemiology Study and the North Carolina Ovarian Cancer Study, treatment-naïve AA women with HGSOC were matched to white women with HGSOC by stage and age. Multiplex immunofluorescence staining was performed on formalin-fixed paraffin-embedded whole tissue sections to measure TILs (CD3+) and T-cell subsets, cytotoxic (CD3+CD8+) and regulatory (CD3+FoxP3+) T-cells. Image analysis was completed on three regions of interest (ROI) selected from the intratumoral region. We categorized immune cell abundance within the tumor, stroma, and overall as <1% and ≥1% positive cells. Multivariable Cox proportional hazard regression models were used to examine the association between immune cell abundance and survival overall and by race. Among 121 AA and 121 white women with HGSOC, more than half (56%) had a higher TIL infiltrate overall, while 33% and 11% had higher levels of cytotoxic and regulatory T-cells, respectively. No differences in immune cell abundance were observed by race. Mean follow-up time was 4.3 ± 5.2 years, and 72% of the women are deceased. Higher levels of TILs and cytotoxic T-cells were associated with better outcomes overall (hazard ratio [HR]=0.68, 95% confidence interval [CI]=0.53, 0.88 and HR=0.59, 95% CI=0.44, 0.80, respectively) and these associations were similar irrespective of tumor/stroma. No association with survival was observed for T-regulatory cells overall and in the tumor; however, improved survival was noted for higher levels of T-regulatory cells in the stroma (HR=0.69, 95% CI=0.49, 0.96). Associations with survival among white women were consistent with the overall findings, but among AA women, all associations were attenuated and not statistically significant. For example, white women with higher overall TILs had a 42% lower risk of all-cause mortality (HR=0.58, 95% CI=0.41, 0.82), whereas the association among AA women was weaker and not statistically significant (HR=0.79, 95% CI=0.54, 1.17). Adjusting for frontline treatment did not substantively impact these findings. Our results add to the existing evidence that a robust TIL infiltrate confers a survival advantage among women with HGSOC; however, AA women may not experience the same survival benefit as white women with HGSOC. An external replication in a larger cohort of ovarian cancer patients and additional investigation, particularly further characterization of the T-cells (e.g., exhaustion, activation) and their co-localization with other prognostically relevant immune cells, is warranted. Citation Format: Lauren C Peres, Christelle Colin-Leitzinger, Sweta Sinha, Jeffrey R. Marks, Jose R. Conejo-Garcia, Anthony J. Alberg, Elisa V. Bandera, Andrew Berchuck, Melissa L. Bondy, Brock C. Christensen, Michele L. Cote, Jennifer A. Doherty, Patricia G. Moorman, Carlos Moran Segura, Jonathan V. Nguyen, Edward S. Peters, Ann G. Schwartz, Paul D. Terry, Christopher M. Wilson, Brooke L. Fridley, Joellen M. Schildkraut. Racial differences in the tumor immune landscape and survival of high-grade serous ovarian carcinoma [abstract]. In: Proceedings of the AACR Virtual Conference: 14th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2021 Oct 6-8. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2022;31(1 Suppl):Abstract nr PO-232.

DNA Methylation Profiles of Ovarian Clear Cell Carcinoma.

Ovarian clear cell carcinoma (OCCC) is a rare ovarian cancer histotype that tends to be resistant to standard platinum-based chemotherapeutics. We sought to better understand the role of DNA methylation in clinical and biological subclassification of OCCC. We interrogated genome-wide methylation using DNA from fresh frozen tumors from 271 cases, applied nonsmooth nonnegative matrix factorization (nsNMF) clustering, and evaluated clinical associations and biological pathways. Two approximately equally sized clusters that associated with several clinical features were identified. Compared with Cluster 2 (N = 137), Cluster 1 cases (N = 134) presented at a more advanced stage, were less likely to be of Asian ancestry, and tended to have poorer outcomes including macroscopic residual disease following primary debulking surgery (P < 0.10). Subset analyses of targeted tumor sequencing and IHC data revealed that Cluster 1 tumors showed TP53 mutation and abnormal p53 expression, and Cluster 2 tumors showed aneuploidy and ARID1A/PIK3CA mutation (P < 0.05). Cluster-defining CpGs included 1,388 CpGs residing within 200 bp of the transcription start sites of 977 genes; 38% of these genes (N = 369 genes) were differentially expressed across cluster in transcriptomic subset analysis (P < 10-4). Differentially expressed genes were enriched for six immune-related pathways, including IFNα and IFNγ responses (P < 10-6). DNA methylation clusters in OCCC correlate with disease features and gene expression patterns among immune pathways. This work serves as a foundation for integrative analyses that better understand the complex biology of OCCC in an effort to improve potential for development of targeted therapeutics.

Ovarian cancer survival by stage, histotype, and pre-diagnostic lifestyle factors, in the prospective UK Million Women Study

BackgroundOvarian cancer is the fifth leading cause of cancer mortality in UK women. Ovarian cancer survival varies by disease stage at diagnosis, but evidence is mixed on the effect of tumour histological type (histotype) and other factors. Methods1.3 million UK women completed a detailed health questionnaire in 1996–2001 and were followed for incident cancers and deaths via linkage to national databases. Using Cox regression models, we estimated adjusted relative risks (RRs) of death from ovarian cancer, by stage at diagnosis, tumour histotype, and 16 other personal characteristics of the women. ResultsDuring 17.7 years’ average follow-up, 13,222 women were diagnosed with ovarian cancer, and 8697 of them died from the disease. Stage at diagnosis was a major determinant of survival (stage IV vs I, RR=10.54, 95% CI: 9.16–12.13). Histotype remained a significant predictor after adjustment for stage and other factors, but associations varied over the follow-up period. Histotype-specific survival was worse for high-grade than low-grade tumours. Survival appeared worse with older age at diagnosis (per 5 years: RR=1.19, 95% CI: 1.15–1.22), higher BMI (per 5-unit increase: RR=1.06, 95% CI: 1.02–1.11), and smoking (current vs never: RR=1.17, 95% CI: 1.07–1.27), but there was little association with 13 other pre-diagnostic reproductive, anthropometric, and lifestyle factors. ConclusionStage at diagnosis is a strong predictor of ovarian cancer survival, but tumour histotype and grade remain predictors of survival even after adjustment for stage and other factors, contributing further evidence of biological dissimilarity between the ovarian cancer histotypes. Obesity and smoking represent potentially-modifiable determinants of survival, but the stronger association with stage suggests that improving earlier diagnosis would have a greater impact on increasing ovarian cancer survival.

An Assessment of Ovarian Cancer Histotypes Across the African Diaspora.

ObjectiveOvarian cancer in Black women is common in many West African countries but is relatively rare in North America. Black women have worse survival outcomes when compared to White women. Ovarian cancer histotype, diagnosis, and age at presentation are known prognostic factors for outcome. We sought to conduct a preliminary comparative assessment of these factors across the African diaspora.MethodsPatients diagnosed with ovarian cancer (all histologies) between June 2016-December 2019 in Departments of Pathology at 25 participating sites in Nigeria were identified. Comparative population-based data, inclusive of Caribbean-born Blacks (CBB) and US-born Blacks (USB), were additionally captured from the International Agency for Research on Cancer and Florida Cancer Data Systems. Histology, country of birth, and age at diagnosis data were collected and evaluated across the three subgroups: USB, CBB and Nigerians. Statistical analyses were done using chi-square and student’s t-test with significance set at p<0.05.ResultsNigerians had the highest proportion of germ cell tumor (GCT, 11.5%) and sex-cord stromal (SCST, 16.2%) ovarian cancers relative to CBB and USB (p=0.001). CBB (79.4%) and USB (77.3%) women were diagnosed with a larger proportion of serous ovarian cancer than Nigerians (60.4%) (p<0.0001). Nigerians were diagnosed with epithelial ovarian cancers at the youngest age (51.7± 12.8 years) relative to USB (58.9 ± 15.0) and CBB (59.0± 13.0,p<0.001). Black women [CBB (25.2 ± 15.0), Nigerians (29.5 ± 15.1), and USB (33.9 ± 17.9)] were diagnosed with GCT younger than White women (35.4 ± 20.5, p=0.011). Black women [Nigerians (47.5 ± 15.9), USB (50.9 ± 18.3) and CBB (50.9 ± 18.3)] were also diagnosed with SCST younger than White women (55.6 ± 16.5, p<0.01).ConclusionThere is significant variation in age of diagnosis and distribution of ovarian cancer histotype/diagnosis across the African diaspora. The etiology of these findings requires further investigation.

The Protein Landscape of Mucinous Ovarian Cancer: Towards a Theranostic.

Simple SummaryMucinous ovarian cancer (MOC) is a rare type of epithelial ovarian cancer, and current treatment regimens for late stage and recurrent disease are inadequate. The ‘gold standard’ treatments are based on large clinical trials that evaluated potential therapies for all ovarian cancer, but MOC was poorly represented in these studies. As such, what works for most cases may not work for MOC. In this review, we discuss the advances in MOC treatment and explore the concept of theranostics—using therapeutic and diagnostic radionuclides against single cell surface receptors expressed highly in MOC. Additionally, we highlight the previous literature that demonstrates the overexpression of certain targets, exploring their potential to be used as theranostic targets.MOC is a rare histotype of epithelial ovarian cancer, and current management options are inadequate for the treatment of late stage or recurrent disease. A shift towards personalised medicines in ovarian cancer is being observed, with trials targeting specific molecular pathways, however, MOC lags due to its rarity. Theranostics is a rapidly evolving category of personalised medicine, encompassing both a diagnostic and therapeutic approach by recognising targets that are expressed highly in tumour tissue in order to deliver a therapeutic payload. The present review evaluates the protein landscape of MOC in recent immunohistochemical- and proteomic-based research, aiming to identify potential candidates for theranostic application. Fourteen proteins were selected based on cell membrane localisation: HER2, EGFR, FOLR1, RAC1, GPR158, CEACAM6, MUC16, PD-L1, NHE1, CEACAM5, MUC1, ACE2, GP2, and PTPRH. Optimal proteins to target using theranostic agents must exhibit high membrane expression on cancerous tissue with low expression on healthy tissue to afford improved disease outcomes with minimal off-target effects and toxicities. We provide guidelines to consider in the selection of a theranostic target for MOC and suggest future directions in evaluating the results of this review.

Body Fat Distribution and Risk of Breast, Endometrial, and Ovarian Cancer: A Two-Sample Mendelian Randomization Study.

Simple SummaryThe causal impact of body fat distribution on female-specific cancers is largely unknown. For the first time we used a two-sample multivariable Mendelian randomization (MR) approach to elucidate the role and causal relations of body composition assessed by segmental bioelectrical impedance analysis on the risks of breast, endometrial and ovarian cancers and their subtypes. We found that abdominal fat content increases the risk for ovarian cancer and its endometrioid and clear cell subtypes independent of overall fat content. General adiposity has a protective effect on risk of breast cancer and its ER- and ER+ subtypes but increases the risk for endometrial cancer, ovarian cancer, and the endometrioid ovarian cancer subtype. This study extends the literature by addressing specifically the causal role of visceral fat on female-specific cancers.Background: Mounting evidence shows that adiposity increases female-specific cancer risk, but the role of body fat distribution is less clear. We used a two-sample Mendelian randomization (MR) approach to elucidate causal relations of body fat distribution to the risks of breast, endometrial and ovarian cancers and their subtypes. Methods: Body composition was assessed using segmental bioelectrical impedance analysis, yielding trunk, arm, and leg fat ratios (TFR, AFR, LFR) and BMI including 195,043 and 434,794 European women, respectively. The sample sizes for the outcomes ranged between 58,396 and 228,951. Causal effects were estimated per one standard deviation increment in the respective exposure within the radial regression framework. Robust sensitivity analyses were performed to verify MR assumptions. In a multivariable MR setting, the proportion of risk attributable to overall and abdominal fat content was assessed. Results: TFR, which represents abdominal fat content, was associated with ovarian cancer and its clear cell and endometrioid histotypes independent of overall fat content. BMI was inversely associated with breast cancer and its ER− and ER+ subtypes, but positively with endometrial cancer and ovarian cancer, including its endometrioid histotype. These estimates were confirmed using AFR as proxy for overall body fat. Conclusions: Visceral adiposity seems to be a driver of elevated ovarian cancer risk, particularly of the endometrioid and clear cell ovarian cancer histotypes. General adiposity decreases the risk of breast cancer but increases the risk of endometrial and ovarian cancer.

Single-cell transcriptomes reveal heterogeneity of high-grade serous ovarian carcinoma.

BackgroundHigh‐grade serous ovarian carcinoma (HGSOC) is the most common and aggressive histotype of epithelial ovarian cancer. The heterogeneity and molecular basis of this disease remain incompletely understood.MethodsTo address this question, we have performed a single‐cell transcriptomics analysis of matched primary and metastatic HGSOC samples.ResultsA total of 13 571 cells are categorized into six distinct cell types, including epithelial cells, fibroblast cells, T cells, B cells, macrophages, and endothelial cells. A subset of aggressive epithelial cells with hyperproliferative and drug‐resistant potentials is identified. Several new markers that are highly expressed in epithelial cells are characterized, and their roles in ovarian cancer cell growth and migration are further confirmed. Dysregulation of multiple signaling pathways, including the translational machinery, is associated with ovarian cancer metastasis through the trajectory analysis. Moreover, single‐cell regulatory network inference and clustering (SCENIC) analysis reveals the gene regulatory networks and suggests the JUN signaling pathway as a potential therapeutic target for treatment of ovarian cancer, which is validated using the JUN/AP‐1 inhibitor T‐5224. Finally, our study depicts the epithelial‐fibroblast cell communication atlas and identifies several important receptor‐ligand complexes in ovarian cancer development.ConclusionsThis study uncovers new molecular features and the potential therapeutic target of HGSOC, which would advance the understanding and treatment of the disease.

Abstract 1045: Combined targeting of actin/tropomyosin and microtubules underlies a potential treatment strategy of epithelial ovarian cancer with cell-cycle dependent synergy

Abstract Anti-microtubule agents are widely used to treat ovarian cancers in the first line and recurrent setting either in combination with platinum or as single agents. However, the majority of patients will experience a recurrence, and most will die with drug resistant disease. We investigated co-targeting the actin cytoskeleton in combination with anti-microtubule agents to increase efficacy of treatment in epithelial ovarian cancers and potentially overcome resistance mechanisms. We examined the presence of actin/tropomyosin 3.1 (Tpm3.1) filaments in a large cohort of clinical specimens from patients with epithelial ovarian cancer of all histotypes using immunohistochemistry. Combinatorial effects of an anti-Tpm3.1 compound (ATM) with both vinorelbine and paclitaxel were evaluated in three ovarian cancer cell lines using cell viability and apoptosis assays. The mechanisms of synergy of both combinations were established using live-cell imaging, fluorescent microscopy, and pathway analysis. We found that Tpm3.1 is abundant and overexpressed in 97% of ovarian cancers examined (558 of 577) representing all histotypes of epithelial ovarian cancer. High levels of Tpm3.1 were also present in all sites sampled and similar at primary diagnosis and at recurrence. ATM displayed both single agent activity as well as synergy with both anti-microtubule drugs to reduce cell viability in all ovarian cancer cell lines tested, including one with platinum resistance. Only vinorelbine, however, synergised with ATM in the induction of apoptosis. Vinorelbine-induced mitotic arrest was significantly prolonged by ATM with elevated activity of the spindle assembly checkpoint, leading to almost one third of total cells dying in mitosis. In contrast, ATM showed minor impact on paclitaxel-induced mitotic defects. Both combinations resulted in a substantial increase in cells arrested in the subsequent G1 phase with a large decrease of both cyclin D1 and E1 as compared to single agents. Upregulation of p21Cip and p27Kip were associated with both combinations. In summary, targeting Tpm3.1-associated actin filaments in combination with anti-microtubule drugs is a promising treatment strategy that should be tested in clinical trials and is potentially applicable to all histotypes of ovarian cancer. Citation Format: Xing Xu, Yao Wang, Nicole Bryce, Katrina Tang, Nicola S. Meagher, Eun Young Kang, Linda E. Kelemen, Martin Köbel, Susan J. Ramus, Michael Friedlander, Caroline E. Ford, Edna C. Hardeman, Peter W. Gunning. Combined targeting of actin/tropomyosin and microtubules underlies a potential treatment strategy of epithelial ovarian cancer with cell-cycle dependent synergy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 1045.

Abstract 2202: Genetic characterization of metastasis and prognosis in high-grade serous ovarian cancer

Abstract High-grade serous ovarian cancer (HGSC) is the most lethal histotype of ovarian cancer and is highly prone to metastasis, with the majority of patients presenting at advanced stages of disease. There are few targeted treatment options for HGSC patients, especially for women with high metastatic tumor burdens. In order to identify potential genetic targets in metastatic disease, we characterized the genomic and transcriptomic alterations of metastatic tumors in HGSC patients. In this study, matched normal tissue, primary, and metastatic tumors from 23 HGSC short-term (ST) survivors (overall survival [OS] &amp;lt;3.5 years) and 14 long-term (LT) survivors (OS &amp;gt;5 years) underwent whole exome and RNA sequencing. We compared somatic mutations, copy number alternations, mutational burdens, differential expression, immune cell fractions, and gene fusion predictions between the primary and metastatic tumors of the ST and LT survival groups. We confirmed that tumors of LT survivors were more likely to have BRCA1 alterations and more copy-altered segments when compared to tumors of ST survivors. There was a higher percentage of shared variants between the primary and metastatic tumors for ST survivors compared to LT survivors. ST survivors also had a greater mutational burden and more predicted gene fusions than LT. We observed few differentially expressed genes between primary and metastatic tumors, but we did observe significant differences between the transcriptomes of LT and ST survivors' tumors. Overall, we observed that HGSC primary and metastatic tumors had similar genomic and transcriptomic landscapes, but we identified genetic characteristics specific to metastatic tumors that correlate with survival. Citation Format: Emilee N. Kotnik, Nicholas C. Spies, Tiandao Li, Matthew Inkman, Jin Zhang, Fernanda Martins-Rodrigues, Ian S. Hagemann, Carolyn K. McCourt, Premal H. Thaker, Andrea R. Hagemann, Matthew A. Powell, David G. Mutch, Christopher A. Maher, Christopher A. Miller, Katherine C. Fuh. Genetic characterization of metastasis and prognosis in high-grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 2202.

Abstract 794: Trends of ovarian cancer incidence by histotype and race/ethnicity in the U.S.: 1992-2017

Abstract Background: Ovarian cancer incidence rates in the U.S. decreased since the early 1970s, which was largely attributed to increasing parity among birth cohorts through 1935 and the introduction of combined oral contraceptives (COCs) in the 1960s. However, COC use prevalence has dramatically declined among 20-34 year-olds since the early 2000s as has parity. Ovarian cancer histotypes share many risk factors, including parity and COC use, but the magnitude of the effects differs by histotype. In addition, the prevalence of these risk factors differs by race/ethnicity. Understanding the trends in ovarian cancer incidence by histotype and race/ethnicity will allow us to consider the impact of changes in risk factor profiles. Methods: Ovarian cancer incidence rates in 1992-2017 were obtained from the Surveillance, Epidemiology, and End Results (SEER) 13 registry. Age-standardized ovarian cancer incidence trends for the three most common histotypes (high-grade serous (HGS), endometrioid and clear cell) and four racial/ethnic groups (Hispanic, Asian/Pacific Islander (API), non-Hispanic Black (NHB), and non-Hispanic White (NHW)) were analyzed using joinpoint regression. Temporal trends of each histotype were analyzed using age-period-cohort models. Results: Joinpoint regression analysis: NHW had the highest incidence rates for HGS and endometrioid cancers, while API had the highest rate for clear cell cancer. HGS cancer incidence declined in all racial/ethnic groups during 1992-2017; NHW had the greatest reduction. Endometrioid cancer incidence decreased in NHW and NHB but increased in Hispanics in recent years. All racial/ethnic groups showed an increasing trend of clear cell cancer incidence. Age-period-cohort analysis: HGS cancer incidence has been decreasing in NHW and API by birth cohort, but not in NHB or Hispanics. There is a decreasing trend in HGS cancer incidence by period in NHW, but no clear period-specific pattern was observed among other racial/ethnic groups. Endometrioid cancer incidence has been decreasing in NHW and API, but increasing in NHB and Hispanics in recent cohorts. Clear cell cancer incidence has been increasing by birth cohort in all racial/ethnic groups. Conclusions: HGS and endometrioid cancer incidence has been decreasing overall, but clear cell cancer incidence has been increasing. This may be due to an improvement in diagnosis with a shift from classifying “carcinoma, not otherwise specified” to clear cell cancer. It is also possible that the impact of shifting patterns of lower COC use and parity are having a bigger impact on clear cell cancer given that these exposures are more protective for this histotype. Further, the introduction of opportunistic salpingectomy may balance any impact of COC use or parity changes for HGS cancer. There are differences in the ovarian cancer incidence trends by histotype and race/ethnicity, highlighting the impact of different preventive strategies. Citation Format: Minh Tung Phung, Celeste Leigh Pearce, Rafael Meza, Jihyoun Jeon. Trends of ovarian cancer incidence by histotype and race/ethnicity in the U.S.: 1992-2017 [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr 794.

STING pathway expression in low-grade serous carcinoma of the ovary: an unexpected therapeutic opportunity?

Ovarian carcinoma histotypes are distinct diseases with variable clinical outcomes and response to treatment. There is a need for new subtype‐specific treatment modalities, especially for women with widespread and chemo‐resistant disease. Stimulator of interferon genes (STING) is a part of the cGAS–STING pathway that mediates innate immune defence against infectious DNA‐containing pathogens and also detects tumour‐derived DNA and generates intrinsic antitumour immunity. The STING signalling pathway is suppressed by several mechanisms in a variety of malignant diseases and, in some cancers that may be a requirement for cellular transformation. The aim of this study was to use immunohistochemistry to evaluate STING protein expression across normal tissue, paratubal and ovarian cysts, and ovarian tumour histotypes including ovarian carcinomas. Herein, we show that the fallopian tube ciliated cells express STING protein, whereas the secretory cells are negative. STING expression differs among ovarian cancer histotypes; low‐grade serous ovarian carcinomas and serous borderline tumours have uniform high STING expression, while high‐grade serous and endometrioid carcinomas have heterogeneous expression, and clear cell and mucinous carcinomas show low expression. As low‐grade serous carcinomas are known to be genomically stable and typically lack a prominent host immune response, the consistently high STING expression is unexpected. High STING expression may reflect pathway activation or histogenesis and the mechanisms may be different in different ovarian carcinoma histotypes. Further studies are needed to determine whether the STING signalling pathway is active and whether these tumours would be candidates for therapeutic interventions that trigger innate immunity activation.

Differential Expression and Copy Number Variation of Gasdermin (GSDM) Family Members, Pore-Forming Proteins in Pyroptosis, in Normal and Malignant Serous Ovarian Tissue.

Gasdermins (GSDM) are members of a family of pore-forming effector proteins which lead to membrane permeabilization and pyroptosis, a lytic cell death with pro-inflammatory characteristics. Recently, two members of the gasdermin family, gasdermin B (GSDMB) and gasdermin E (GSDME), were shown to suppress tumor growth, through the involvement of cytotoxic lymphocytes. Other studies also reported the important functions of gasdermins in various cancer types including gastric cancer, hepatocarcinoma, and cervix and breast cancer. However, gasdermins have not been previously studied in the context of serous ovarian cancer. Here, we showed that gasdermin D (GSDMD) and gasdermin C (GSDMC) expression increases in serous ovarian cancer; in contrast, the expression of GSDME and PJVK (Pejvakin, DFNB59) is downregulated, compared to healthy ovaries, in multiple independent gene expression datasets. We found that copy number gains are highly frequent (present in approximately 50% of patients) in genes encoding GSDMD and GSDMC in ovarian cancer, in line with their upregulated expression in serous ovarian cancer. Moreover, we observed that the expression of GSDMB and GSDMD, but not of GSDME, is different among several histotypes of epithelial ovarian cancer. Therefore, we propose that differential expression and copy number variations of certain gasdermins might be associated with the development of serous ovarian cancer, in which different members of the family have distinct functions; however, further research is required in in vivo models to understand how changes in gasdermin family members mechanistically contribute to serous ovarian cancer.

Targeting the actin/tropomyosin cytoskeleton in epithelial ovarian cancer reveals multiple mechanisms of synergy with anti-microtubule agents.

Anti-microtubule agents are widely used to treat ovarian cancers, but the efficacy is often compromised by drug resistance. We investigated co-targeting the actin/tropomyosin cytoskeleton and microtubules to increase treatment efficacy in ovarian cancers and potentially overcome resistance. The presence of tropomyosin-3.1 (Tpm3.1) was examined in clinical specimens from ovarian cancer patients using immunohistochemistry. Combinatorial effects of an anti-Tpm3.1 compound, ATM-3507, with vinorelbine and paclitaxel were evaluated in ovarian cancer cells via MTS and apoptosis assays. The mechanisms of action were established using live- and fixed-cell imaging and protein analysis. Tpm3.1 is overexpressed in 97% of tumour tissues (558 of 577) representing all histotypes of epithelial ovarian cancer. ATM-3507 displayed synergy with both anti-microtubule agents to reduce cell viability. Only vinorelbine synergised with ATM-3507 in causing apoptosis. ATM-3507 significantly prolonged vinorelbine-induced mitotic arrest with elevated activity of the spindle assembly checkpoint and mitotic cell death; however, ATM-3507 showed minor impact on paclitaxel-induced mitotic defects. Both combinations substantially increased post-mitotic G1 arrest with cyclin D1 and E1 downregulation and an increase of p21Cip and p27Kip. Combined targeting of Tpm3.1/actin and microtubules is a promising treatment strategy for ovarian cancer that should be further tested in clinical settings.

Reduced SKP1 and CUL1 expression underlies increases in Cyclin E1 and chromosome instability in cellular precursors of high-grade serous ovarian cancer

BackgroundHigh-grade serous ovarian cancer (HGSOC) is the most common and lethal ovarian cancer histotype. Chromosome instability (CIN, an increased rate of chromosome gains and losses) is believed to play a fundamental role in the development and evolution of HGSOC. Importantly, overexpression of Cyclin E1 protein induces CIN, and genomic amplification of CCNE1 contributes to HGSOC pathogenesis in ~20% of patients. Cyclin E1 levels are normally regulated in a cell cycle-dependent manner by the SCF (SKP1–CUL1–FBOX) complex, an E3 ubiquitin ligase that includes the proteins SKP1 and CUL1. Conceptually, diminished SKP1 or CUL1 expression is predicted to underlie increases in Cyclin E1 levels and induce CIN.MethodsThis study employs fallopian tube secretory epithelial cell models to evaluate the impact diminished SKP1 or CUL1 expression has on Cyclin E1 and CIN in both short-term (siRNA) and long-term (CRISPR/Cas9) studies.ResultsSingle-cell quantitative imaging microscopy approaches revealed changes in CIN-associated phenotypes and chromosome numbers and increased Cyclin E1 in response to diminished SKP1 or CUL1 expression.ConclusionsThese data identify SKP1 and CUL1 as novel CIN genes in HGSOC precursor cells that may drive early aetiological events contributing to HGSOC development.

246P Impact of genetically predicted elevated concentrations of C-reactive protein on ovarian cancer risk: A Mendelian randomization study

C-reactive protein (CRP) is the inflammation-responsible protein and a significant rise of the plasma concentration of CRP is pervasive in the progress of ovarian cancer. However, there are few studies that comprehensively evaluate the correlation between CRP concentrations and ovarian cancer and the causal effect remains unknown. With a Mendelian randomization (MR) approach, we were able to investigate the causal relationship between genetically predicted CRP levels and ovarian cancer risk. Utilizing 32 CRP-related single nucleotide polymorphisms as instrumental variables identified by the latest genome-wide association studies, we investigated the correlation between genetically predicted CRP and ovarian cancer risk using summary statistics from the Ovarian Cancer Association Consortium (25,509 cases and 40,941 controls). The Inverse variance weighted (IVW) method was applied to estimate the causality between genetically elevated CRP concentrations and ovarian cancer risk. To further evaluate the pleiotropy, the weighted median and the MR-Egger regression method were implemented. Subgroup analyses according to different histotypes of ovarian cancer were also conducted. An inverse association was observed between genetically predicted one-unit increase in the log-transformed CRP concentrations and ovarian cancer (OR = 0.93, 95%CI = 0.87-1.00 p = 0.047). When results were examined by histotypes, an inverse association was observed between genetically predicted one-unit increase in the log-transformed CRP concentrations and endometrioid ovarian cancer (OR = 0.80, 95%CI = 0.70-0.91 p = 0.001), low-grade serous ovarian cancer (OR = 0.70, 95%CI = 0.58-0.86 p = 0.001) and serous ovarian cancer (OR = 0.84, 95%CI = 0.74-0.96 p = 0.012). Additionally, the results demonstrated the absence of the horizontal pleiotropy. MR findings provide evidence for a causal relationship between genetically predicted one-unit increase in the log-transformed CRP concentrations and reduced ovarian cancer risk, overall and among specific histotypes. Further studies are warranted to investigate the underlying mechanism.

Low junctional adhesion molecule-A expression is associated with an epithelial to mesenchymal transition and poorer outcomes in high-grade serous carcinoma of uterine adnexa

High-grade serous carcinoma of uterine adnexa (HGSC) is the most frequent histotype of epithelial ovarian cancer and has a poor 5-year survival rate due to late-stage diagnosis and the poor efficacy of standard treatments. Novel biomarkers of cancer outcome are needed to identify new targetable pathways and improve personalized treatments. Cell-surface screening of 26 HGSC cell lines by high-throughput flow cytometry identified junctional adhesion molecule 1 (JAM-A, also known as F11R) as a potential biomarker. Using a multi-labeled immunofluorescent staining coupled with digital image analysis, protein levels of JAM-A were quantified in tissue microarrays from three HGSC patient cohorts: a discovery cohort (n = 101), the Canadian Ovarian Experimental Unified Resource cohort (COEUR, n = 1158), and the Canadian Cancer Trials Group OV16 cohort (n = 267). Low JAM-A level was associated with poorer outcome in the three cohorts by Kaplan–Meier (p = 0.023, p < 0.001, and p = 0.036, respectively) and was an independent marker of shorter survival in the COEUR cohort (HR = 0.517 (0.381–703), p < 0.001). When analyses were restricted to patients treated by taxane–platinum-based chemotherapy, low JAM-A protein expression was associated with poorer responses in the COEUR (p < 0.001) and OV16 cohorts (p = 0.006) by Kaplan–Meier. Decreased JAM-A gene expression was an indicator of poor outcome in gene expression datasets including The Cancer Genome Atlas (n = 606, p = 0.002) and Kaplan–Meier plotter (n = 1816, p = 0.024). Finally, we observed that tumors with decreased JAM-A expression exhibited an enhanced epithelial to mesenchymal transition (EMT) signature. Our results demonstrate that JAM-A expression is a robust prognostic biomarker of HGSC and may be used to discriminate tumors responsive to therapies targeting EMT.

Abstract 5123: Proteogenomic characterization reveals mitotic kinase and replication stress implicated in ovarian high-grade serous cancer

Abstract High-grade serous cancer (HGSC), the most prevalent histotype of ovarian cancer, has the lowest survival rates and is the leading cause of gynecological cancer-related deaths in the developed world. HGSC is characterized by the presence of nearly universal TP53 mutations, diverse and widespread chromosomal instability, and a general shortage of targetable driving mutations. The major clinical needs in HGSC include the identification of alternative therapeutic targets and an improved understanding of the mechanisms driving chromosomal heterogeneity. We prospectively collected 83 new ovarian HGSC samples and 20 normal precursor tissue samples (Fallopian tube, FT) for deep characterization at the genomic, transcriptomic, proteomic, and phosphoproteomic levels. We were also able to obtain cytobrush samples of Fallopian tube epithelium and provide the first extensive comparison of HGSC and FT proteomes and phosphoproteomes that used surgical specimens rather than cell lines. The ability to compare tumor and normal precursor tissues provided new biological insights regarding the role of increased proliferation in promoting replication stress in a DNA repair-deficient background, potentially explaining the high degree of chromosomal instability associated with HGSC. Our collection protocols were specifically designed to minimize the effect of ischemia on protein phosphorylation, which has been identified as a significant confounding variable. Thus, we were able to identify novel signaling interactions that would have been lost in the background of ischemic stress, most notably the activation of CDK4 and CDK7. Widespread increases in protein phosphorylation and pathway activation in tumors compared to normal tissues, particularly in the proliferation-associated CDK/RB and AURKA pathways that are targetable by FDA-approved inhibitors, provide a rational basis for the use of these therapeutics in ovarian cancer. Phosphosite-specific analysis of CDKs and FANCD was consistent with an elevated response to replication stress, potentially induced by proliferative signals. Additionally, pathway-level observations from the retrospective TCGA cohort were conserved in the prospective cohort, including histone acetylation marks associated with homologous repair deficiency. In addition to confirming key features of HGSC from previous proteogenomic study, analysis of prospectively collected HGSC samples provided significant new insights stemming from direct comparisons to normal precursor tissues; deep phosphoproteomics revealed new insights regarding the potential role of proliferation-induced replication stress in promoting the characteristic chromosomal instability of HGSC and suggested novel therapeutic targets for use in precision medicine trials. Citation Format: Jason McDermott, Osama Arshad, Vladislav Petyuk, Yi Fu, Marina Gritsenko, Chia-Feng Tsai, Samuel Payne, Mathangi Thiagarajan, Christopher Kinsinger, Ana Robles, Emily Boja, Henry Rodriguez, Daniel Chan, Bing Zhang, Zhen Zhang, Li Ding, Richard Smith, Tao Liu, Karin Rodland. Proteogenomic characterization reveals mitotic kinase and replication stress implicated in ovarian high-grade serous cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 5123.