Ovarian Cancer Cases Research Articles

High-Grade Serous Ovarian Cancer during Pregnancy: From Diagnosis to Treatment.

Due to the rarity of ovarian cancer diagnosed during pregnancy, the literature on the treatment of subtypes of epithelial ovarian cancer in pregnancy is sparse. The aim of our review was to analyze cases of high-grade serous ovarian cancer in pregnancy. The PubMed and Scopus databases were searched for relevant articles published in English between January 2000 and December 2023. The references of all the relevant reviews found were also checked to avoid omitting eligible studies. Information on the all retrieved cases was extracted and reviewed in detail. The most important detail was the subtype of high-grade serous ovarian cancer, which was referred to as serous adenocarcinoma (grade 2 or grade 3) in older cases. We found eleven cases with relevant details of high-grade serous ovarian cancer diagnosed in pregnancy. Despite the small number of cases we found, our study demonstrated the importance of an accurate initial vaginal ultrasound at the first examination in pregnancy and the safety of diagnostic surgery and chemotherapy in pregnancy. There have not been long-term follow-ups of patients' oncologic and obstetric outcomes. As patients should be comprehensively informed, more detailed case reports or series with longer follow-up periods are needed.

Abstract 3947: Non-BRCA variants in hereditary breast and ovarian cancer patients in the Northern Mexico population

Abstract Background: Hereditary cancer syndromes explain 5-10% of all cancer cases. Germline pathogenic variants in BRCA1 and BRCA2 genes (BRCA) are present in 2-3% of all breast cancer (BC), and 15% of all ovarian cancer (OC) cases. BRCA1 and BRCA2 pathogenic variants (PV) represent 25-28% of BC and 40% of OC patients with a positive familial history. BRCAs are the most studied genes for the prevalence, family history, preventive surgeries, and target treatment options in both BC and OC. There are other genes, important in the diagnosis, pathogenesis, and treatment options of the patients: TP53, PALB2, CHEK2, among others. This study aims to identify the prevalence of non- BRCA genes related to the development of hereditary breast and ovarian cancer syndrome in patients of Northeast Mexico. Methods: This is a multicenter study that recruited patients from two reference oncology centers in Nuevo Leon, Mexico: the CECIL (The CUCC Early Cancer Detection Clinic) Hereditary Cancer Registry and Hereditary Cancer Program from Tec Salud. From March of 2016 to March of 2023, a total of 872 patients meeting NCCN criteria were evaluated by Medical Geneticists from both centers and were tested with NGS multigene cancer panels. Results: A total of 665 (76.26%) patients with a clinical diagnosis of HBOC (Hereditary Breast Hereditary Cancer Syndrome) were included. We found 310 (46.6%) patients had at least one variant, 180 (58%) with at least one pathogenic variant, and 130 (41%) with a VUS (a variant of uncertain significance). BRCA1 was found in 79 (43.8%) and BRCA2 in 32 (17.7%) of all PV. Non-BRCA PV were found in 69 (38.3%) patients: 4 ATM, 2 BLM, 3 BRIP1, 22 CHEK2, 4 CDKN2A, 5 MUTYH, 10 PALB2, 4 RAD51C, 2 SDHA, 2 TP53, 2 WRN, CDH1, CDK4, DICER, MSH3, NBN, PTEN, RAD50, USH2A one of each. Is remarkable that 19 of the 22 patients with CHEK2 and 5 of the 10 patients with PALB2 had the recurrent PV c.707T>C and c.2167_2168del, respectively. Conclusions: Non-BRCA PV in Northern Mexico corresponds to one-third of the BC and OC cases, including HRD (homologous recombination deficiency) genes. HDR patient carriers are potential targets of iPARP therapies. This project reinforces the fact that multigene panels should be employed to ensure a complete diagnosis in hereditary cancer patients. Citation Format: Carlos H. Burciaga-Flores, Diana C. Perez-Ibave, Maria L. Garza-Rodriguez, Oscar Vidal-Gutierrez, Cynthia M. Villarreal-Garza, Dione Aguilar y Mendez. Non-BRCA variants in hereditary breast and ovarian cancer patients in the Northern Mexico population [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3947.

Abstract 800: Spatial accessibility of gynecologic oncologists and time to surgery in a diverse cohort of women with ovarian cancer in Northern California

Abstract Introduction: To expand our understanding of factors contributing to racial and ethnic disparities in ovarian cancer outcomes, we examined the association between spatial accessibility of gynecologic oncologists and time from cancer diagnosis to surgery in the KPROCS Study, a diverse cohort of women diagnosed with ovarian cancer between 2000-2018 at Kaiser Permanente Northern California (KPNC). Spatial medical accessibility is a component of healthcare access that captures the proximity and availability of healthcare resources in the area. Methods: Ovarian cancer cases were identified through the KPNC Cancer Registry. Demographic and clinical information was extracted from KPNC databases. Neighborhood characteristics from the California Neighborhoods Data System were linked to the residential addresses of cases at the time of diagnosis. Spatial medical accessibility was measured using the 2-step floating catchment area method based on the location of the infusion centers where KPNC gynecologic oncologists practice and the residence location of cohort members. We used generalized estimating equations with independent correlation structure and robust standard errors to examine the association between spatial accessibility of gynecologic oncologists and time to ovarian cancer surgery, adjusting for year and age at diagnosis, stage, histotype, race, ethnicity, neighborhood socioeconomic status (nSES), and receipt of neoadjuvant chemotherapy. Results: The cohort comprised 4,910 women with ovarian cancer, of whom 3,304 had surgery at KPNC. Of this group, 13% were Hispanic, 14% were non-Hispanic (NH) Asian American women, 5% NH Black women, and 67% NH White women. The proportion of women residing in areas of the lowest spatial accessibility of gynecologic oncologists was highest among NH White women (26%) and women residing in the highest quintile of nSES (29%). The median time from diagnosis to surgery was 4 days (interquartile range 22 days). In adjusted analyses, not including the information on spatial accessibility, the time from diagnosis to surgery was 5.1 days longer (95% CI 1.5, 8.7) for NH Black women than NH White women. After adding information on spatial accessibility, this time did not considerably change, resulting in a 5.3-day (95% CI 1.7, 8.9) difference. In this model, the lowest quintile of spatial accessibility of gynecologic oncologists was associated with a longer time from diagnosis to surgery, but this association was not statistically significant (0.4 days difference, 95% CI -1.3, 2.0). Summary: In our preliminary analyses, spatial accessibility of gynecologic oncologists was not found to be a contributing factor to the disparity in time from diagnosis to surgery between NH Black and NH White women. Further analyses will examine time from diagnosis to chemotherapy overall and stratified by racial and ethnic groups. Citation Format: Ekaterina Chirikova, Pushkar P. Inamdar, Valerie McGuire, Salma Shariff-Marco, Valerie S. Lee, Lindsay J. Collin, Carola T. Sanchez-Diaz, Juraj Kavecansky, C Bethan Powell, Jennifer A. Doherty, Lawrence H. Kushi, Elisa V. Bandera, Scarlett L. Gomez. Spatial accessibility of gynecologic oncologists and time to surgery in a diverse cohort of women with ovarian cancer in Northern California [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 800.

Abstract 7135: Preclinical effects of Tumor Treating Fields (TTFields) with PARP inhibitors in ovarian cancer

Abstract Purpose: Among gynecological malignancies, ovarian cancer is the leading cause of mortality. Poly (ADP-ribose) polymerase inhibitors (PARPi) represent standard-of-care treatment for selected cases of advanced epithelial ovarian cancer. PARPi exhibit sensitivity in homologues recombination deficient (HRD) tumors, in which there are mutations in the Fanconi Anemia (FA)-BRCA pathway, while about 75% of ovarian cancer patients are homologues recombination proficient (HRP). TTFields are non-invasive electric fields that disrupt cellular processes critical for cancer cell viability and tumor progression. Recent research showed that TTFields induce an HRD-like state (also known as BRCAness state) in various cancer types. The current study aims to investigate the impact of TTFields applied together with PARPi in ovarian cancer preclinical models. Methods: In vitro, A2780 (HRP), OVCAR3 (HRD), and A2780cis (platinum-resistant) ovarian cancer cells were treated with TTFields (1 V/cm RMS, 200 kHz, 72 h), alone or with addition of PARPi (olaparib or niraparib, at various concentrations). Efficacy was measured by analyzing cell count, colony formation, and apoptosis induction. The overall effect was calculated by multiplying cell count with colony formation. TTFields-treated cells were evaluated for the expression of FA-BRCA pathway proteins and for formation of γH2AX, a DNA damage marker, using Western blot and fluorescent microscopy, respectively. In vivo, ID8-fLuc (HRP) cells were inoculated intraperitoneally to 6-8-week-old C57BL/6 mice. Seven days post inoculation, mice were treated with sham-vehicle, TTFields, olaparib (50 mg/kg), or both over a period of four weeks. Tumor growth was analyzed using bioluminescent imaging at treatment cessation, and survival analysis was performed. Results: TTFields application resulted in reduced cell count, increased overall effect, and increased apoptosis in vitro. When TTFields were applied together with PARPi, a high and moderate synergistic interaction was shown respectively the BRCA wild-type A2780 cells and the platinum-resistant A2780cis cells. However, in the BRCA mutant OVCAR-3 cells the effect was additive. A downregulation of FA-BRCA protein expression was confirmed after TTFields treatment of the ovarian cells, with consequent DNA damage. In the tumor-bearing mice, TTFields and olaparib co-treatment resulted in reduced tumor volume and a survival benefit relative to the monotherapies and to control-treated mice. Conclusions: The data suggest potential advantages for TTFields concomitant with PARPi in ovarian cancer, even without underlying BRCA mutations - consistent with the BRCAness state induced by TTFields - and also suggests benefits in platinum-resistant ovarian cancer. Citation Format: Yani Berckmans, Hila Ene, Kerem Ben-Meir, Antonia Martinez-Conde, Roni Monin, Bieke Van den Ende, Sara Van Mechelen, Roni Frechtel-Gerzi, Hila Gabay, Rotem Engelman, Eyal Dor-On, Adi Haber, Moshe Giladi, Uri Weinberg, Yoram Palti, Ignace Vergote, An Coosemans. Preclinical effects of Tumor Treating Fields (TTFields) with PARP inhibitors in ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7135.

Abstract 4688: EC359, A new therapeutic drug for the treatment of low grade serous ovarian cancer

Abstract Background: Ovarian cancer (OCa) is the deadliest of all gynecologic cancers in the United States. About 10% of all cases of serous ovarian cancer have the unusual histology named low-grade serous carcinomas (LGSOC), that has a distinct clinical behavior with a unique molecular landscape. LGSOC is characterized by a younger age at diagnosis, indolent progression, and chemotherapy resistance. BRAF and KRAS mutations occur in 33% and 35% of LGSOC cases, respectively. LGSOC is frequently detected when the malignancy is in advanced stage and LGSOC relapses in about 70% of patients with advanced disease. Therefore, new targeted therapies are required. Since LGSOC uniquely expresses mutations of either BRAF or KRAS, and because Leukemia Inhibitor Factor (LIF) expression is induced by oncogenes such as KRAS, we reason that the LIF/LIFR axis represents a unique target for treating LGSOC. The objective of this study is to test the utility of blocking LIF/LIFR axis using LIFR inhibitor EC359 in treating LGSOC. Methods: The expression of LIF and its receptor LIFR was profiled using multiple established LGSOC cells and primary LGSOC model cells. The effects of EC359 on LGSOC cells were evaluated using cell viability, colony formation, and apoptosis assays. Mechanistic investigations were conducted with Western blotting, reporter assays and RT-qPCR analysis. The in vivo efficacy of LIFR inhibitor EC359 as a targeted therapy was investigated using LGSOC cell-based xenografts. Results: Western blot analysis confirmed expression of LIFR and LIF in established LGSOC and primary LGSOC cells and functional autocrine loop of LIF/LIFR signaling. The treatment with the LIFR inhibitor EC359 significantly reduced LGSOC cell viability, cell survival, and increased apoptosis. The activation of downstream LIFR signaling including STAT3, mTOR, AKT, and p42/44 MAPKs markedly decreased by EC359 treatment. EC359 enhanced the efficacy of trametinib, a currently used medication of LGSOC. EC359+trametinib as a combination therapy showed more efficacy over monotherapy of EC359 or trametinib in reducing cell viability and colony formation. Using cell-based xenograft and PDX models, we demonstrated that the EC359 at 5mg/kg dose significantly reduced the LGSOC xenograft growth compared to the vehicle control. Conclusions: Together, our findings support the existence of LIF/LIFR autocrine loops, and EC359 is a viable treatment option for LGSOC. Citation Format: Yasmin Lyons, William Cole Arnold, Behnam Ebrahimi, Bindu Santhamma, Edward R. Kost, Hareesh B. Nair, Suryavathi Viswanadhapalli, Ratna K. Vadlamudi. EC359, A new therapeutic drug for the treatment of low grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4688.

Abstract 1649: Large scale multi-omics concordance study of cyclin E1 identifies high expressing tumors lacking CCNE1 gene alterations across multiple tumor indications

Abstract Cyclin E1 is a key regulator of the G1/S transition and is thought to cause excessive entry into the cell cycle. CCNE1 is amplified in a range of tumor indications, and its amplification is associated with poorer prognosis and resistance to chemotherapy. Cyclin E1 is also being investigated as a potential biomarker for inhibitors targeting the replication stress response. Understanding the best way to quantify cyclin E1 overexpression is fundamental to support patient selection approaches for these inhibitors. In many cases, gene amplification correlates with increased cyclin E1 protein expression; however, there are a proportion of high-grade serous ovarian cancer and basal-like breast cancer cases where cyclin E1 protein overexpression does not correlate with gene amplification. In this study, we investigate if this phenomenon is observed in other cancers and some of the potential mechanisms causing cyclin E1 overexpression. We used a multi-omics approach to assess cyclin E1 expression in 1417 formalin-fixed paraffin-embedded (FFPE) patient tumor resections across 6 indications (SCCHN, Bladder, NSCLC, TNBC, Ovarian & SCLC). We used copy number variation (CNV) determined by next generation sequencing (NGS), NanoString nCounter RNA analysis and protein expression by immunohistochemistry (IHC). 830 were evaluable for all 3 methods and demonstrated CCNE1 gene amplification by NGS (CNV normalized log2 ratio ≥1.5) in 3.3% cases. Using a threshold of mRNA z-score >2, 17% cases had high CCNE1 mRNA and 29% had high cyclin E1 protein (H-score ≥100). 15.7% (130/830) cases had high protein expression without gene amplification or gain, crucially this was found across all 6 indications (n=20/102 SCCHN, n=29/166 Bladder, n=34/232 NSCLC, n=15/76 SCLC, n=15/143 TNBC & n=17/118 Ovarian). Impaired protein degradation has been proposed as a mechanism that may result in high Cyclin E1 expression. From a panel of 1600 genes, we assessed the relationship between cyclin E1 and mRNA expression of 57 genes involved in the ubiquitin-proteasome pathway in 1239 samples across the 6 indications. We assessed mutations which could impair ubiquitination in 915 samples across the 6 indications. We also assessed the methylation status of 893 genes associated with ubiquitin ligases or deubiquitinases in a cohort of 170 TNBC samples. Further investigation into other mechanisms causing cyclin E1 overexpression is required. IHC provides an ideal platform to build our understanding of cyclin E1 expression spatially. Our results indicate that assessing Cyclin E1 protein overexpression instead of CCNE1 gene amplification could greatly broaden the population of patients who could benefit from replication stress response kinase inhibitors, as cyclin E1 overexpression correlates with genomic instability and replication stress. Citation Format: Sophie E. Willis, Gemma N. Jones, Shaan Gill, Emma V. Jones, Amelia Raymond, Barrett Nuttall, Sophie Kirschner, Sakshi Gulati, Paola Marco-Casanova, Benedetta Lombardi, David Jenkins, Felicia S. Ng, James Hadfield, Paul Waring, Helen K. Angell, Heike Laman. Large scale multi-omics concordance study of cyclin E1 identifies high expressing tumors lacking CCNE1 gene alterations across multiple tumor indications [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 1649.

Abstract 2195: Intrauterine device use and risk of invasive epithelial ovarian cancer: A population-based case-control study

Abstract Introduction: Ovarian, fallopian tube, and primary peritoneal cancers (hereafter referred to as ovarian cancer) are the most fatal gynecologic cancers. Thus, it is imperative to identify strategies that can reduce the risk of the disease. Several contraceptive methods have been shown to be associated with a reduced risk of ovarian cancer, including combined oral contraceptives, injectable progestins, and tubal ligation. However, the use of these contraceptive methods has been decreasing in the U.S., with a growing preference for intrauterine devices (IUDs) for pregnancy prevention. Previous case-control studies on the association between IUD use and ovarian cancer risk have found inconsistent results. Notably, previous studies had small sample sizes and did not restrict to invasive epithelial tumors. The current analysis assessed the association between IUD use and risk of invasive epithelial ovarian cancer in a large population-based case-control study. Methods: This analysis used data from 1,713 people diagnosed with primary invasive epithelial ovarian cancer (cases) and 2,348 cancer-free people (controls) participating in a case-control study conducted in Los Angeles, CA from 1992-2010. The study consisted of four waves of recruitment with similar enrollment and data collection methods. Logistic regression models were fit to assess the association between IUD use and risk of invasive epithelial ovarian cancer. All models were adjusted for age, race/ethnicity, education, first-degree family history of ovarian cancer, endometriosis, body mass index, duration of combined oral contraceptive use, parity, duration of breastfeeding, tubal ligation, and study wave. Heterogeneity across the study waves and the ovarian cancer histotypes was evaluated using standard meta-analysis techniques. Results: There was no statistically significant association between IUD use and risk of invasive epithelial ovarian cancer (odds ratio=1.09, 95% confidence interval 0.93-1.28). This result was consistent across the study waves and the ovarian cancer histotypes (p-values for heterogeneity>0.05). Conclusion: IUD use was not associated with the risk of invasive epithelial ovarian cancer. Analysis by IUD type (i.e., hormone-releasing vs copper IUDs) was not possible in this study as these data were not collected. Future research should examine whether the type of IUD (i.e. copper versus hormone-releasing) may have different effects on risk of ovarian cancer. Citation Format: Minh Tung Phung, Yuting Wang, Alice W. Lee, Malcolm C. Pike, Anna H. Wu, Celeste Leigh Pearce. Intrauterine device use and risk of invasive epithelial ovarian cancer: A population-based case-control study [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2195.

Abstract 2204: Evaluating ovarian cancer risk factors in the Mexican Teachers′ Cohort

Abstract Purpose: Ovarian cancer is the most lethal gynecologic cancer in North America, yet our understanding of ovarian cancer risk factors in Mexican women is limited. The aim of the present study was to prospectively evaluate associations between reproductive and lifestyle factors and incident ovarian cancer risk among Mexican women. Methods: The Mexican Teachers′ Cohort (ESMaestras) is a large, prospective, population-based cohort of women (n=115,306) living in a culturally, geographically, and economically diverse 12-state area in Mexico. Reproductive and lifestyle factors were collected on baseline questionnaires administered between 2006-2008, with additional questionnaires collected from the cohort in 2011, and 2014. During follow-up, 187 incident ovarian cancer cases were identified, including 101 via self-report on 2011 and 2014 questionnaires, as well as an additional 85 through linkage with mortality databases, and 3 via other administrative- and cancer registry-based linkages (2 of 3 were also identified via the mortality database linkage). Of the self-reported incident cases, 5 have been validated via mortality databases and 4 via linkage with an administrative database; validation of the remaining self-reported cases is ongoing. Primary analyses examined associations between established ovarian cancer risk factors and incident ovarian cancer. Age-adjusted hazard ratios (HRs) and 95% confidence intervals (CIs) were estimated using Cox proportional hazards regression. Results: Women in the Mexican Teachers′ Cohort that used hormonal contraceptives (HC), were parous, or had a tubal ligation experienced reduced ovarian cancer risks during follow-up (ever HC use vs. never HR 0.70 [95% CI 0.51-0.95], parous vs. nulliparous 0.48 [0.35-0.68], ever tubal ligation vs. never 0.87 [0.59-1.28]). Ovarian cancer risk was elevated among women with a positive family history of breast cancer (1.34 [0.76-2.36]). Women with a history of endometriosis were at increased ovarian cancer risk (3.43 [1.41-8.34]). Taller adult height (>159 cm vs <150 cm) was not associated with ovarian cancer risk among women in this cohort. Risk estimates were consistent and, in some instances, more pronounced (i.e., HC use and tubal ligation) when limited to incident ovarian cancer cases confirmed via linkage with mortality databases (n=90). Conclusions: Ovarian cancer risk factors identified in the Mexican Teachers′ Cohort were generally consistent with associations reported in predominantly non-Hispanic white populations. More research is needed to better understand ovarian cancer etiology among populations under-represented in cancer research. Citation Format: Britton Trabert, Liliana Gómez Flores Ramos, Marion Brochier, Elisa V. Bandera, Jennifer A. Doherty, Scarlett L. Gomez, Lawrence H. Kushi, Alejandro Mohar, Martín Lajous. Evaluating ovarian cancer risk factors in the Mexican Teachers′ Cohort [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2204.

Abstract 2334: Computational methods for optimizing marker selection, clonal lineage reconstruction, and longitudinal tracking of clonal dynamics via circulating tumor DNA (ctDNA)

Abstract Background: Technologies for blood-based profiling of tumor DNA (“liquid biopsy”) have offered great prospects for non-invasive early cancer diagnosis, treatment monitoring, and clinical guidance, but further advances in computational models and data analysis to optimize monitoring protocols and develop liquid biopsy as a robust quantitative assay of tumor clonal evolution. Methods: We propose new computational methods to improve our ability to characterize tumor clonal dynamics from circulating tumor DNA (ctDNA). Our methods address how to apply ctDNA assays most effectively to two distinct questions in profiling tumor clonal dynamics: 1) How to apply longitudinal ctDNA data to refine phylogenetic tree models of clonal evolution, and 2) how to most effectively characterize changes in clonal frequencies that may be indicative of treatment response or tumor progression. We pose these questions computationally in terms of a probabilistic framework for optimally identifying maximum likelihood markers for the preceding tasks and applying measured marker concentrations to their solution. We apply this framework by first evaluating the distribution of plausible clonal lineage models using bootstrap samples over pre-treatment tissue-based genetic variation data, then refining these lineage models and the clonal frequencies we can infer from them over successive longitudinal samples of selected markers. Results: We tested our method on synthetic data under various model assumptions and showed the method to be effective at refining distribution tree models and clonal frequencies over longitudinal samples so as to minimize measures of tree distance relative to the ground truth. We further apply the methods to a real ovarian cancer case and show their ability to develop and refine a clonal lineage model and assess clonal frequencies. Conclusion: Our methods show the power of ctDNA assays in conjunction with computational optimization to lead to improved marker selection, clonal lineage reconstruction, and tracking of clonal dynamics, with potential for more precise and quantitative profiling of tumor progression enabling improved clinical decision-making. Citation Format: Xuecong Fu, Yueqian Deng, Zhicheng Luo, William Laframboise, David Bartlett, Russell Schwartz. Computational methods for optimizing marker selection, clonal lineage reconstruction, and longitudinal tracking of clonal dynamics via circulating tumor DNA (ctDNA) [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2334.

Matrix Metalloproteinase-7 Promoter Site Single Nucleotide Polymorphism (-181A>G) in Epithelial Ovarian Cancer in the Eastern Indian Population.

Matrix metalloproteinase-7 (MMP7) plays multiple roles in different stages of tumor development. Elevated MMP7 activity has been reported in ovarian cancer. Single nucleotide polymorphism (SNP) of promoter sites of the MMP7 gene has been shown to cause alteration in gene expression, hence resulting in changes in susceptibility to various diseases and tumor development. The current study evaluated the association of epithelial ovarian cancer risk with MMP7 promoter site -181A>G polymorphism in the population of eastern India. The present case-control study included 64 histopathologically confirmed cases of epithelial ovarian cancer and 100 control subjects. The MMP7 -181A/G polymorphism was identified using polymerase chain reaction-restriction fragment length polymorphism. The association between genotypes and epithelial ovarian cancer risk was analyzed by odds ratio (OR) with a 95% confidence interval. The frequencies of AA, AG, and GG genotypes in ovarian cancer cases were 37.5%, 46.9%, and 15.6%, respectively, while that of control subjects were 56%, 36%, and 8%, respectively, in the study population. By taking the wild-type AA genotype as a reference, it was found that genotypeGG was associated with a significant risk for epithelial ovarian cancer (OR: 2.92). Frequency distribution of genotypes did not show any significant association with tumor characteristics like the International Federation of Gynecology and Obstetrics (FIGO) stage, histology, lymph node status, and distant metastasis. The present study demonstrated the association of MMP7 promoter site -181 GG genotype and the G allele with increased risk for epithelial ovarian cancer in the eastern Indian population.

Exploration of Preliminary Objective Triage by Menopause Score and CA 125 Result Prior to Accelerating Fast-Track Booking for Suspected Ovarian Cancer-A Role for the Pathway Navigator?

The 28-days-to-diagnosis pathway is the current expected standard of care for women with symptoms of ovarian cancer in the UK. However, the anticipated conversion rate of symptoms to cancer is only 3%, and use of the pathway is increasing. A rapid triage at the moment of receipt of the referral might allow resources to be allocated more appropriately. In secondary care, multidisciplinary teams (MDTs) use the risk of malignancy index (RMI) score, (multiply menopausal status pre = 1 or post = 3 × ultrasound score = 0 - 3 × the CA 125 level), using a score of >200, to triage urgency and management in possible ovarian cancer cases. The most powerful determinant of the RMI score variables is CA 125 level, an objective number. Could a simple modification of the RMI score retain a high sensitivity for cancer whilst improving specificity and, consequently, decrease the morbidity of false-positive classification? To test this hypothesis, a retrospective evaluation of an ovarian two-week-wait telephone clinic of one consultant gynaecological oncologist was undertaken. Enquiry re menopause status was scored as one for pre- and three for postmenopausal or uncertain. CA 125 levels of >67 u/mL for premenopausal and >23 u/mL for postmenopausal women were used to precipitate urgent cross-sectional imaging requests and MDT opinions. These CA 125 cut thresholds were calculated using an assumption that the RMI imaging score, regardless of whether the result was available, could be three. We contemplate that women who did not exceed a provisional RMI score of >200 might be informed they are extremely unlikely to have cancer, removed from the malignancy tracker and appropriate follow-up arranged. One hundred and forty consecutive cases were analysed; 43% were deemed premenopausal and 57% postmenopausal. Twenty of the women had cancer, eighteen (90%) of whom had an RMI > 200. One hundred and twenty were benign, and only twenty-three (19%) classified as urgent cases in need of accelerated referral to imaging. In contrast, CA 125 > 35 u/mL, whilst retaining the sensitivity of 90%, misclassified 36 (30%) of the benign cases. It is possible that a telephone triage via a questionnaire determining menopausal status and the CA 125 result could offer a sensitivity for cancer of 90% and urgent expert review of under 20% of benign cases. This rapid initial telephone assessment could be presented by a trained pathway navigator, physician associate or nurse specialist. Substantial savings in NHS cancer services resources, anxieties all around and reduced patient morbidity may occur as a result.

Abstract A045: Improving the diagnostic accuracy of an ovarian cancer triage test using a joint miRNA-protein model

Abstract Background: Multianalyte protein assays that combine several protein biomarkers with an individual’s menopausal status can aid in the preoperative prediction of ovarian cancer among women presenting with an adnexal mass. Serum microRNAs (miRNAs) are another class of biomarkers which have also shown potential to discriminate ovarian cancer cases from benign lesions or healthy controls. Here we investigate the complementarity of miRNA and protein-based approaches. Methods: The population consisted of serum samples from n=678 total study subjects. The training set was provided by Aspira Women’s Health, comprising n=568 women undergoing preoperative evaluation for an adnexal mass (n=333 benign and n=235 malignant). An independent, external validation set (n=110) comprised study subjects enrolled in prospective collection protocols at Brigham and Women’s Hospital, including n=59 subjects with benign masses or healthy controls and n=51 ovarian cancer cases. Among the 51 cases in the validation set, n=20 were FIGO Stage I/II and n=31 were FIGO Stage III/IV. Histologies included n=34 serous and n=17 non-serous. All samples underwent miRNA profiling using a custom 179-miRNA panel optimized for serum analysis using the Fireplex® circulating miRNA assay (Abcam, Cambridge, MA). Proteins were measured using ELISA kits by Aspira. Seven proteins were provided for each patient, including CA-125, as well as age and menopausal status. To reduce the dimensionality of the miRNA data, we employed a forward regression algorithm, which selects a subset of miRNA to optimize linear separation between cases and controls. The miRNA panel was combined with the protein and metadata to train a neural network to diagnose ovarian cancer. We used receiver operating characteristic curves to compare the effectiveness of models trained on miRNA + protein + metadata (joint) vs miRNA alone vs protein + metadata as assessed by the area under the curve (AUC). Results: The joint model produced an AUC 0.95 on the validation set. The miRNA and protein + metadata models offered an AUC of 0.84 and 0.9, respectively. By histology, the joint model offered the highest sensitivity among cancers which were serous and early-stage (89%) and among early-stage cancers overall (90%) when compared to miRNA alone (56% and 80%) or protein+metadata (67% and 65%). Conclusions: These results suggest that miRNA, protein, and metadata are complimentary tools, and the proposed model, which uses all data types simultaneously, is shown to offer the optimal AUC on the external validation set, when compared to the same model trained on miRNA alone or proteins and metadata. The joint model appears to be particularly effective for early-stage, high-risk histologies. This data will be useful to inform ovarian cancer screening and early detection efforts. Citation Format: James W. Webber, Laura Wollborn, Sudhanshu Mishra, Allison Vitonis, Daniel W. Cramer, Ryan Phan, Todd Pappas, Dipanjan Chowdhury, Kevin M. Elias. Improving the diagnostic accuracy of an ovarian cancer triage test using a joint miRNA-protein model [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A045.

Abstract B091: Mechanisms underlying the omental support of ovarian cancer peritoneal metastasis

Abstract More than 80% of ovarian cancer (OC) cases have metastasized to the peritoneal cavity at diagnosis. The five-year survival rate for these patients is 25%. Within the peritoneal cavity, the most common and early site of metastasis is the omentum, a well-vascularized, specialized adipose tissue that arises off the greater curvature of the stomach. Because OC homes to the omentum, it is removed as a standard of care for patients with peritoneal metastases. In mouse models, the omentum is also an early metastatic site, and omentectomy reduces tumor expansion. The mechanism by which the omentum promotes OC growth is unknown, perhaps due to the complex omental microenvironment. The omentum contains many features that could impact OC seeding. It is covered by a mesothelial lining that extends in a sheet anchoring the omentum to surrounding tissues and is highly perfused by blood vessels. It contains lymphoid aggregates or milky spots that may contribute to pro- and anti-tumor immunity. This study explores the association of OC metastases with specific omentum features. We intraperitoneally injected luciferase-expressing ID8 OC cells to mimic high-grade serous OC metastasis. Using high-resolution, spatial ex vivo bioluminescence imaging (BLI), we found that tumor nodules preferentially formed in adipocyte-rich regions of the omentum and the mesentery, another peritoneal tissue favorable for OC seeding. To determine whether adipocytes, the most abundant omental cell type, are the primary support of OC, we crossed Adiponectin Cre+ and DTA mice to generate mice lacking white and brown adipocytes from birth. To overcome the metabolic syndrome the fatless mice develop, they receive subcutaneous fat transplants dorsally, referred to as distal adipocyte rescue of lipodystrophy (DARL) mice. Littermate controls receive sham surgeries. The blood triglyceride, glucose, and insulin levels are normalized post-transplant. Thus, the peritoneal cavity lacks mature adipocytes, but the mice have typical metabolic profiles, allowing us to study the role of omental adipocytes in peritoneal metastasis. Once the mice recovered from surgery, they were intraperitoneally injected with luciferase-expressing ID8s. While it was hypothesized that OC metastatic seeding within the adipocyte-free omentum and associated peritoneum would be impaired without local mature adipocytes, BLI revealed that the tumor burden was not decreased in DARL mice. Notably, specific regions of OC seeding, where mature adipocytes would have localized if present, such as the omentum and mesentery, retained tumor nodules in DARL mice. This conserved OC localization suggests that other cells in this specific microenvironment might be responsible for metastatic spread. To identify these cells, studies are ongoing to profile these regions in the DARL and control mice via flow cytometry and single-cell RNA sequencing. By unraveling the support for OC cells in the omentum, therapeutic strategies can be identified to repolarize the metastatic milieu and halt further spread to improve patient outcomes. Citation Format: Rachel Mintz, Alexandre Gallerand, Jichang Han, Sarah Ning, Wei Zou, Mary Wohltmann, Bernd Zinselmeyer, Gwendalyn Randolph. Mechanisms underlying the omental support of ovarian cancer peritoneal metastasis [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B091.

Abstract A042: History of infertility and risk of ovarian cancer in the women’s health initiative

Abstract Background: Given the consistent relationship between reproductive factors (e.g. parity) and risk of epithelial ovarian cancer, several studies have investigated the relation between infertility and ovarian cancer with conflicting results. Prior research has suggested differences in risk by specific infertility subgroups, which may have contributed to the conflicting findings. Further, few studies examined associations by ovarian cancer histotypes or were able to disentangle the influence of infertility vs. fertility treatment. Differences across studies could also have been influenced by different study populations (e.g., population-based vs. clinical population/registry of in-vitro fertilization [IVF]) and lack of consistent statistical control for important confounding factors including nulliparity, number of pregnancies, and age at first pregnancy. Finally, prior prospective studies have had limited follow-up, thus not capturing cancers that occur after menopause and which may have different risk factor profiles. Our objective was to determine the association between history of infertility and risk of postmenopausal ovarian cancer in a population that had not received treatment with IVF. Methods: We utilized the Women’s Health Initiative (n=114,761) with over 25 years of follow-up. At study baseline participants were asked whether they had ever tried to become pregnant for more than one year without becoming pregnant and whether a reason was found. Cox proportional hazards models were used to calculate the hazard ratios (HRs) of incident ovarian cancer comparing participants with a history of infertility to parous participants without infertility. Logistic regression models were used to calculate odds ratios (OR) for prevalent ovarian cancer at study baseline. Results: Approximately 16% of participants reported a history of infertility. 1,376 participants reported prevalent ovarian cancer at study baseline and 852 cases of ovarian cancer were diagnosed during study follow-up. In the prospective analyses, no statistically significant association was observed between infertility and risk of ovarian cancer overall (HR=1.16; 95% CI=0.98-1.37), by histotype, or with any specific infertility diagnoses. When prevalent ovarian cancer was examined, those reporting a history of infertility had a greater odds of ovarian cancer diagnosis (1.34; 95% CI=1.13-1.58) at WHI cohort baseline. This association was present for most infertility diagnoses with the strongest associations for hormonal/ovulatory (OR=1.97;95% CI=1.24-3.12), tubal/uterine factor (OR=1.63; 95% CI=1.15-2.31), and male factor (OR=1.71; 95% CI=1.19-2.47) infertility. Conclusions: We observed no significant association between infertility history and incident ovarian cancer in our population of postmenopausal participants. An association between infertility and ovarian cancer was present when prevalent ovarian cancer cases were examined, consistent with prior analyses that show stronger associations between ovarian cancer risk factors and ovarian cancer among younger women. Citation Format: Holly Harris, Kimberly Lind, Cynthia Thomson, Nazmus Saquib, Aladdin Shadyab, Peter Schnatz, Rogelio Robles-Morales, Lihong Qi, Howard Strickler, Denise Roe, Leslie Farland. History of infertility and risk of ovarian cancer in the women’s health initiative [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A042.

Diagnostic accuracy of diffusion weighted imaging on MRI in suspected cases of ovarian cancer, keeping histopathology as gold standard.

Objective: To assess the diagnostic accuracy of diffusion weighted imaging on MRI in patients of ovarian cancer with histopathology considered as gold standard. Study Design: Cross-sectional study. Setting: Department of Radiology, Tertiary Care Hospital Kharian. Period: February 2022 to August 2022. Material & Methods: Non-probability, consecutive sampling was performed from 60 patients. After receiving informed consents, the suspected female patients with age 15 to 65 years went under MRI. The results were compared with histopathological findings and diagnostic potential of MRI was calculated by 2x2 table. The findings of both the modalities were compared by correlation analysis with p<0.05 considered as significant. Results: The sensitivity and specificity of MRI were estimated to be 92.68% and 73.68%. The positive predictive value and negative predictive value were estimated to be 88.37% and 82.35%. The diagnostic accuracy was found to be 86.66%. The findings of MRI and histopathology were significantly (p<0.05) correlated with a value of 0.685. Conclusion: The use of MRI is highly recommended in diagnosis of ovarian cancer.

Abstract B043: Feasibility of a traceback approach to facilitate genetic testing in the Genetic Risk Analysis in Ovarian Cancer (GRACE) study

Abstract Current guidelines state that genetic testing is clinically indicated for all individuals diagnosed with ovarian cancer (OC). Individuals with a prior diagnosis of OC who have not received genetic testing represent missed opportunities to identify individuals and their families with inherited variants that put them at a higher risk for cancer. The Genetic Risk Analysis in Ovarian Cancer (GRACE) study aims to address this significant healthcare gap using a “traceback testing” approach to identify individuals with a prior diagnosis of OC and to offer genetic risk information to them and their family members. Tumor registry data at two integrated health care systems (Kaiser Permanente Northwest and Colorado) identified cases of OC diagnosed 1998-2020 with no prior genetic testing or testing limited to BRCA1/2. The study aimed to provide genetic risk information to OC survivors as well as family members of patients who were deceased by leveraging stored pathology specimens for germline testing. Comprehensive genetic testing using a panel of 60 cancer risk genes was offered; genetic testing of the familial variant was offered to first- and second-degree relatives if a pathogenic or likely pathogenic variant was detected. A total of 317 eligible OC survivors were identified from tumor registry and medical record review; 79 (25%) consented for testing. Sixteen (21%) were found to carry a pathogenic or likely pathogenic variant in a cancer risk gene. Genes with pathogenic variants included BRCA1/2, BARD1, PMS2, DICER1, MUTYH, APC, and SDHB. Of 73 relatives eligible for cascade testing, 24 consented (≈ 33% uptake) and 9 were found to carry the familial variant. The uptake of testing by OC survivors and their relatives reflects a strong interest in genetic risk information. However, practical barriers must be addressed to provide genetic risk information to relatives of individuals who are deceased. The GRACE study can inform broad implementation of future traceback programs, providing information to prevent and mitigate the burden of ovarian and other hereditary cancers. Citation Format: Larissa L. White, Yolanda K. Prado, Ana A. Reyes, Jamilyn M. Zepp, Jennifer Sawyer, Mahesh Maiyani, Rachel Zucker, Sarah Vertrees, Alan F. Rope, Sheila Weinmann, Mika Caruncho, Sandra Soo-Jin Lee, Nora B. Henrikson, Heather Spencer Feigelson, Jessica Ezzell Hunter. Feasibility of a traceback approach to facilitate genetic testing in the Genetic Risk Analysis in Ovarian Cancer (GRACE) study [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B043.

Evaluation of antihypertensive medications use and survival in patients with ovarian cancer: a population-based retrospective cohort study

BackgroundDespite declining mortality in most countries and in Lithuania, ovarian cancer burden has remained high. Studies have indicated that antihypertensive medications use may help to improve ovarian cancer survival, however findings remain controversial. The aim of the study was to analyse the association between post-diagnosis antihypertensive medications intake and cancer-specific survival in ovarian cancer patients.MethodsThis retrospective cohort study included 588 ovarian cancer cases diagnosed between 2013 and 2015. Hazard ratios (HR) and corresponding 95% confidence intervals (95%CI) were estimated using multivariable Cox proportional hazards models to assess associations between antihypertensive medications and ovarian cancer-specific mortality.ResultsIn total, 279 (47%) patients died during the follow-up; 242 (87%) of them died due to ovarian cancer. The risk of ovarian cancer death was reduced in angiotensin-converting enzyme inhibitors (ACE inhibitors) users vs. non-users (HR 0.55, 95% CI: 0.36–0.83). Subgroup analysis showed better ovarian cancer survival in higher dose ACE inhibitors users (HR 0.46, 95% CI: 0.28–0.77, p for trend 0.002); the effect was also stronger in age 51–65 years, stage I–III, surgery or chemotherapy treatment, pre-diagnosis ACE inhibitor users’ and pre-diagnosis hypertension subgroups. The risk of cancer-specific death was slightly lower among calcium-channel blocker and angiotensin-receptor blocker users and higher among beta-blocker users as compared to non-users, however chance and confounding could not be ruled out. We found no association between the use of centrally and peripherally acting antiadrenergic agents and diuretics and risk of ovarian cancer-specific mortality.ConclusionsOur findings imply that post-diagnosis use of ACE inhibitors may be associated with reduced ovarian cancer-specific mortality; however, further research is needed for the comprehensive assessment.

Abstract B053: Lipid metabolism and lipidomics of ovarian clear cell carcinoma: a comprehensive analysis

Abstract Ovarian clear cell carcinoma (OCCC) is a chemoresistant subtype of ovarian cancer accounting for 5-12% of all epithelial ovarian cancer cases. Lipid metabolism has been reported to be involved in platinum resistance and resistance to ferroptosis induction in various cancer types. However, the metabolomic and lipidomic landscape of OCCC has not been characterized. To explore the metabolic processes driving the aggressive nature of advanced OCCC, we carried out global metabolomic and lipidomic profiling on 64 early and advanced ovarian cancer samples, including tumors with corresponding metastases. Snap frozen tissue from 29 OCCC, 22 high-grade serous carcinoma (HGSOC), and 13 endometrioid ovarian carcinoma (EnOC) cases were included. Hydrophilic interaction liquid chromatography (HILIC)-mass spectrometry was performed to quantify the relative steady-state level of 318 unique metabolites. Principal component analysis (PCA) showed a distinct separation between OCCC and HGSOC/EnOC samples, mainly driven by short and medium chain acylcarnitine and hydroxylated acylcarnitine esters that were significantly more abundant in OCCC. Acylcarnitines are intermediaries of fatty acid beta-oxidation (FAO), and their enrichment in OCCC patient samples might indicate a difference in fatty acid utilization and lipid metabolism compared to OCCC and HGSOC/EnOC. FAO has been linked to redox homeostasis in cancer cells, acting as a protective factor against lipid peroxidation through selective depletion of certain lipid species. To explore whether deeper lipidomic changes in OCCC accompany increased acylcarnitine production, we performed global complex lipid detection on 7 OCCCs and 3 HGSOC tissue samples using reverse phase liquid chromatography and mass spectrometry. Six-hundred and fifty-seven unique lipid species were successfully identified. A comparison of lipid class abundances between OCCC and HGSOC uncovered increased levels of medium chain acylcarnitines in OCCC, corroborating the HILIC findings. Moreover, the levels of cholesterol esters and ceramides with polyunsaturated fatty acid chains were also more abundant in OCCC. Conversely, choline plasmalogens, a lipid class known to induce lipid peroxidation and ferroptosis cell death exhibited significantly lower abundance in OCCC. Additionally, saturated ethanolamine plasmalogens and ceramides containing saturated fatty acids were decreased in OCCC. In summary, our study reports significant differences in the lipid metabolism of OCCC compared to other major ovarian cancer subtypes. The observed decrease in peroxidation-prone lipid species might indicate the involvement of FAO in OCCC’s redox homeostasis and highlights FAO as a potential novel mechanism of platinum resistance in OCCC. Ongoing studies, presented at the meeting include the metabolomic and lipidomic profiling of a large panel of ovarian cancer cell lines to identify those that best model patient sample metabolism. These models will subsequently be used for in vitro and in vivo studies to evaluate FAO as a potential therapeutic target in OCCC. Citation Format: Agnes J. Bilecz, Roya AminiTabrizi, Hardik Shah, Ernst Lengyel. Lipid metabolism and lipidomics of ovarian clear cell carcinoma: a comprehensive analysis [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B053.

Abstract B085: Carcinoma-associated mesenchymal stem cells promote high-grade serous ovarian cancer metastasis and drive tumor heterogeneity at the metastatic site through direct mitochondrial transfer

Abstract High-grade serous ovarian cancer (HGSC) is the most common and lethal form of ovarian cancer, accounting for over 70% of ovarian cancer cases. HGSC mortality is largely driven by early and diffuse transcoelomic spread from the primary site throughout the peritoneal cavity, resulting in roughly three-quarters of cases presenting with advanced stage disease at time of diagnosis. Following detachment from the primary tumor, disseminated ovarian cancer cells are spread by the peritoneal fluid and ascites where they must adapt to their new microenvironment to survive and successfully form metastases. Crucial to this spread is the formation of multicellular aggregates containing both cancer and non-malignant stromal cells, which enhance cancer cell survival and are associated with poor clinical outcome. While most studies on HGSC multicellular aggregates have focused on ovarian cancer cells alone, the interactions between ovarian cancer cells and other non-malignant cells have yet to be fully elucidated. Prior work by our group have shown that stromal-progenitor cells, termed carcinoma-associated mesenchymal stem/stromal cells (CA-MSCs), enhance HGSC metastasis through direct cellular interaction and formation of heterocellular CA-MSC:cancer cell complexes. Here we demonstrate CA-MSCs enhance metastasis by preferentially donating their mitochondria to cancer cells with the least amount of endogenous mitochondria content (‘mito poor’ cancer cells), increasing their ability to survive and driving tumor heterogeneity at the metastatic site in vivo. Mito poor cancer cells were shown to have decreased proliferative capacity, increased sensitivity to platinum-based chemotherapy and display decreased oxidative phosphorylation (OXPHOS) compared to ‘mito rich’ cancer cells. Primary patient-derived CA-MSCs rescue this vulnerable phenotype by increasing proliferation, chemoresistance and OXPHOS in mito poor cancer cells. These findings were validated in a fully autologous system using CA-MSCs and cancer cells derived from the same patient to prevent confounding effects of cellular response to foreign organelle/DNA. Through lentiviral knockdown of the mitochondrial motor protein MIRO1 we further demonstrate mitochondrial transfer is necessary for CA-MSC-mediated rescue of mito poor cancer cells. Further, we developed a haplotype-specific quantification of mitochondrial DNA to differentiate CA-MSC from endogenous cancer cell mitochondria which was used to quantify the amount of CA-MSC mitochondrial donation and demonstrate donated mitochondria persist in cancer cells up to 14 days. Importantly, CA-MSC mitochondrial donation occurred in vivo and was associated with decreased survival in an orthotopic ovarian cancer murine model. Genomic barcoding was used to quantify tumor cell clonal heterogeneity; using this system we demonstrate CA-MSC mitochondrial donation significantly enhance tumor cell heterogeneity at the metastatic site in vivo. Collectively, we report CA-MSC mitochondrial transfer as a driver of HGSC progression, heterogeneity and metastasis. Citation Format: Leonard G. Frisbie, Catherine A. Pressimone, Roja Baruwal, Geyon L. Garcia, Zanib Javed, Claudette St. Croix, Simon Watkins, Michael Calderone, Huda I. Atiya, Nadine Hempel, Alexander Pearson, Lan G. Coffman. Carcinoma-associated mesenchymal stem cells promote high-grade serous ovarian cancer metastasis and drive tumor heterogeneity at the metastatic site through direct mitochondrial transfer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr B085.

Abstract A013: Auranofin induces lethality driven by reactive oxygen species in high-grade serous ovarian cancer cells

Abstract High-grade serous ovarian cancer (HGSOC) accounts for 70% of ovarian cancer cases in the clinical setting; the survival rate for this disease remains remarkably low due to the lack of a long-term consolidation therapy following standard platinum-based chemotherapy. There is minimal improvement in the survival rate of this disease due to the development of resistance to platinum drugs as the disease recurs. The purpose of this study was to develop a novel treatment modality against HGSOC using the gold complex auranofin (AF). AF primarily functions as a pro-oxidant agent through the inhibition of thioredoxin reductase (TrxR), an antioxidant enzyme that is overexpressed in ovarian cancer. We explored the effect of AF on TrxR activity and various mechanisms of cytotoxicity using HGSOC cells that are clinically sensitive (PEO1) or resistant (PEO4) to platinum. We treated PEO1 cells and PEO4 cells with AF for 72 hours and analyzed its short-term toxicity by assessing cell viability and DNA content by flow cytometry, and the long-term anti-proliferative capacity using colony formation assays. We also assessed the mechanisms of cell death induced by AF including the activation of mechanisms of apoptosis, activation of executor caspases -3 and -7, cleavage of poly-(ADP-ribose) polymerase (PARP), changes in the mitochondrial membrane potential (MMP), and DNA damage. In addition, we studied the interaction between AF and another pro-oxidant, L-buthionine sulfoximine (L-BSO), an anti-glutathione (GSH) agent. We demonstrate that AF potently inhibits the activity of TrxR at non-cytotoxic concentrations while reducing the viability of HGSOC cells regardless of their sensitivities to platinum. We showed that AF induces accumulation of reactive oxygen species (ROS), triggers the depolarization of the mitochondrial membrane, and kills HGSOC cells by inducing apoptosis. AF-induced cell death and morphological effects were abrogated by the ROS scavenger, N-acetyl cysteine (NAC). In addition, the lethality of AF in HGSOC was associated with the activation of caspase-3/7, cleavage of PARP, and the generation of DNA damage, effects that were prevented by the ROS scavenger NAC. Finally, when AF and L-BSO were combined, we observed a synergistic lethality against HGSOC cells, which was mediated by a further increase in ROS with a decrease in the antioxidant, GSH. In summary, our results support the concept that AF can be used alone to kill HGSOC cells by causing ROS-mediated apoptosis. Furthermore, we demonstrate that a large depletion of antioxidants caused by combining AF and L-BSO is highly efficient in synergistically killing HGSOC cells. These findings suggest that the combination of AF and L-BSO is a potential option to develop a consolidation therapy against HGSOC, which can overcome the problem of platinum resistance during recurrent stages of the disease. Citation Format: Farah H. Abdalbari, Elvis M. Jaramillo, Benjamin N. Forgie, Estelle Tran, Alicia A. Goyeneche, Carlos M. Telleria. Auranofin induces lethality driven by reactive oxygen species in high-grade serous ovarian cancer cells [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A013.