Serous Carcinoma Research Articles

Spatial transcriptomics reveals discrete tumour microenvironments and autocrine loops within ovarian cancer subclones

High-grade serous ovarian carcinoma (HGSOC) is genetically unstable and characterised by the presence of subclones with distinct genotypes. Intratumoural heterogeneity is linked to recurrence, chemotherapy resistance, and poor prognosis. Here, we use spatial transcriptomics to identify HGSOC subclones and study their association with infiltrating cell populations. Visium spatial transcriptomics reveals multiple tumour subclones with different copy number alterations present within individual tumour sections. These subclones differentially express various ligands and receptors and are predicted to differentially associate with different stromal and immune cell populations. In one sample, CosMx single molecule imaging reveals subclones differentially associating with immune cell populations, fibroblasts, and endothelial cells. Cell-to-cell communication analysis identifies subclone-specific signalling to stromal and immune cells and multiple subclone-specific autocrine loops. Our study highlights the high degree of subclonal heterogeneity in HGSOC and suggests that subclone-specific ligand and receptor expression patterns likely modulate how HGSOC cells interact with their local microenvironment.

Mesothelioma: morphologic and immunohistochemical findings.

This paper reviews some basic and some new concepts in the diagnosis of mesothelioma. The term "malignant mesothelioma" is no longer recommended; rather, any tumor labeled "mesothelioma" is presumed to be malignant. Clinical and radiologic information is very useful in the diagnosis of mesothelioma; in particular, nodular pleural thickening on CT is usually amarker of malignancy. The literature on markers that separate mesotheliomas from metastatic carcinomas has become very complex and frequently misleading, with many recommended markers actually demonstrating poor specificity. However, newer data show that acombination of HEG1 (clone SKM9-2) and claudin‑4 staining provides extremely high accuracy in separating epithelioid mesotheliomas from non-small-cell lung carcinomas with just two immunostains. This combination works at other sites as well, but caution should be used when high-grade serous carcinoma is in the differential, because all "mesothelioma" markers can also stain high-grade serous carcinomas. There are, unfortunately, no sensitive or specific markers for sarcomatoid mesotheliomas. Avariety of immunohistochemical and fluorescence in situ hybridization (FISH) markers are useful in separating benign from malignant mesothelial proliferations; immunohistochemal staining for BAP1, MTAP (or CDKN2A FISH), and NF2/Merlin (or NF2 FISH) will enable the diagnosis of most mesotheliomas. Mesothelioma in situ is now recognized as either asingle layer of bland cuboidal mesothelial cells that have lost BAP1, and sometimes MTAP, on immunohistochemical staining, or aprocess that is morphologically identical to awell-differentiated papillary mesothelial tumor that has lost BAP1/MTAP. Mesothelioma in situ probably always progresses to invasive mesothelioma, but this process is often quite slow.

Proteomic profiles of peritoneal fluid-derived small extracellular vesicles correlate with patient outcome in ovarian cancer.

Cancer-derived small extracellular vesicles (sEVs) are capable of modifying the tumor microenvironment and promoting tumor progression. Ovarian cancer (OvCa) is a lethal malignancy that preferentially spreads through the abdominal cavity. Thus, the secretion of such vesicles into the peritoneal fluid could be a determinant factor in the dissemination and behavior of this disease. We designed a prospective observational study to assess the impact of peritoneal fluid-derived sEVs (PFD-sEVs) in OvCa clinical outcome. For this purpose, 2 patient cohorts were enrolled: patients with OvCa who underwent a diagnostic or cytoreductive surgery and nononcological patients, who underwent abdominal surgery for benign gynecological conditions and acted as the control group. Systematic extraction of PFD-sEVs from surgical samples enabled us to observe significant quantitative and qualitative differences associated with cancer diagnosis, disease stage, and platinum chemosensitivity. Proteomic profiling of PFD-sEVs led to the identification of molecular pathways and proteins of interest and to the biological validation of S100A4 and STX5. In addition, unsupervised analysis of PFD-sEV proteomic profiles in high-grade serous ovarian carcinomas (HGSOCs) revealed 2 clusters with different outcomes in terms of overall survival. In conclusion, comprehensive characterization of PFD-sEV content provided a prognostic value with potential implications in HGSOC clinical management.

Ovarian serous carcinoma with stomach metastasis: a rare case report and literature review.

Ovarian cancer is a common tumor among women. It is often asymptomatic in the early stages, with most cases already at stage III to IVE at the time of diagnosis. Direct spread and lymphatic metastasis are the primary modes of metastasis, whereas hematogenous spread is rare. An initial diagnosis of ovarian cancer that has metastasized to the stomach is also uncommon. Therefore, clear treatment methods and prognostic data for such metastasis are lacking. In our hospital, we encountered a patient with an initial imaging diagnosis of a gastric tumor and a history of an ovarian tumor with endoscopic abdominal metastasis. Based on the characteristics of the case, the two tumors were considered to be the same. After chemotherapy, a partial response was observed in the stomach and pelvic lesions, suggesting the effectiveness of the treatment. Through three treatments of recurrence, gastroscopy confirmed the stomach to be a metastatic site. Therefore, determining the primary source of advanced tumors is crucial in guiding treatment decisions. Clinicians must approach this comprehensively, relying on thorough evaluation and personal experience.

Survival prediction of ovarian serous carcinoma based on machine learning combined with pathological images and clinical information

Survival prediction of ovarian serous carcinoma based on machine learning combined with pathological images and clinical information

TP53 mutations and the association with platinum resistance in high grade serous ovarian carcinoma

ObjectivesAlterations in the tumor suppressor TP53 gene are the most common mutations in high grade serous ovarian carcinoma. The impact of TP53 mutations on clinical outcomes and platinum resistance is controversial. We sought to evaluate the genomic profile of high grade serous ovarian carcinoma and explore the association of TP53 mutations with platinum resistance. MethodsNext generation sequencing data was obtained from our institutional database for patients with high grade serous ovarian carcinoma undergoing primary treatment. Sequencing data, demographic, and clinical information was reviewed. The primary outcome analyzed was time to recurrence or refractory diagnosis. Associations between the primary outcome and different classification schemes for TP53 mutations (structural, functional, hot spot, pathogenicity scores, immunohistochemical staining patterns) were performed. Results209 patients met inclusion criteria. TP53 mutations were the most common mutation. There were no differences in platinum response with TP53 hotspot mutations or high pathogenicity scores. Presence of TP53 gain-of-function mutations or measure of TP53 gain-of function activity were not associated with platinum resistance. Immunohistochemical staining patterns correlated with expected TP53 protein function and were not associated with platinum resistance. ConclusionsTP53 hotspot mutations or high pathogenicity scores were not associated with platinum resistance or refractory disease. Contrary to prior studies, TP53 gain-of-function mutations were not associated with platinum resistance. Estimation of TP53 gain-of-function effect using missense mutation phenotype scores was not associated with platinum resistance. The polymorphic nature of TP53 mutations may be too complex to demonstrate effect using simple models, or response to platinum therapy may be independent of initiating TP53 mutation.

The CHK1 inhibitor prexasertib in BRCA wild-type platinum-resistant recurrent high-grade serous ovarian carcinoma: a phase 2 trial

The multi-cohort phase 2 trial NCT02203513 was designed to evaluate the clinical activity of the CHK1 inhibitor (CHK1i) prexasertib in patients with breast or ovarian cancer. Here we report the activity of CHK1i in platinum-resistant high-grade serous ovarian carcinoma (HGSOC) with measurable and biopsiable disease (cohort 5), or without biopsiable disease (cohort 6). The primary endpoint was objective response rate (ORR). Secondary outcomes were safety and progression-free survival (PFS). 49 heavily pretreated patients were enrolled (24 in cohort 5, 25 in cohort 6). Among the 39 RECISTv1.1-evaluable patients, ORR was 33.3% in cohort 5 and 28.6% in cohort 6. Primary endpoint was not evaluable due to early stop of the trial. The median PFS was 4 months in cohort 5 and 6 months in cohort 6. Toxicity was manageable. Translational research was an exploratory endpoint. Potential biomarkers were investigated using pre-treatment fresh biopsies and serial blood samples. Transcriptomic analysis revealed high levels of DNA replication-related genes (POLA1, POLE, GINS3) associated with lack of clinical benefit [defined post-hoc as PFS < 6 months]. Subsequent preclinical experiments demonstrated significant cytotoxicity of POLA1 silencing in combination with CHK1i in platinum-resistant HGSOC cell line models. Therefore, POLA1 expression may be predictive for CHK1i resistance, and the concurrent POLA1 inhibition may improve the efficacy of CHK1i monotherapy in this hard-to-treat population, deserving further investigation.

High-dose ascorbate exerts anti-tumor activities and improves inhibitory effect of carboplatin through the pro-oxidant function pathway in uterine serous carcinoma cell lines

ObjectiveUterine serous carcinoma is a highly aggressive non-endometrioid subtype of endometrial cancer with poor survival rates overall, creating a strong need for new therapeutic strategies to improve outcomes. High-dose ascorbate (vitamin C) has been shown to inhibit cell proliferation and tumor growth in multiple preclinical models and has shown promising anti-tumor activity in combination with chemotherapy, with a favorable safety profile. We aimed to study the anti-tumor effects of ascorbate and its synergistic effect with carboplatin on uterine serous carcinoma cells. MethodsCell proliferation was evaluated by MTT and colony formation assays in ARK1, ARK2 and SPEC2 cells. Cellular stress, antioxidant ability, cleaved caspase 3 activity and adhesion were measured by ELISA assays. Cell cycle was detected by Cellometer. Invasion was measured using a wound healing assay. Changes in protein expression were determined by Western immunoblotting. ResultsHigh-dose ascorbate significantly inhibited cell proliferation, caused cell cycle arrest, induced cellular stress, and apoptosis, increased DNA damage, and suppressed cell invasion in ARK1 and SPEC2 cells. Treatment of both cells with 1 mM N-acetylcysteine reversed ascorbate-induced apoptosis and inhibition of cell proliferation. The combination of ascorbate and carboplatin produced significant synergistic effects in inhibiting cell proliferation and invasion, inducing cellular stress, causing DNA damage, and enhancing cleaved caspase 3 levels compared to each compound alone in both cells. ConclusionsAscorbate has potent antitumor activity and acts synergistically with carboplatin through its pro-oxidant effects. Clinical trials of ascorbate combined with carboplatin as adjuvant treatment of uterine serous carcinoma are worth exploring.

Podocalyxin promotes the formation of compact and chemoresistant cancer spheroids in high grade serous carcinoma

High grade serous carcinoma (HGSC) metastasises primarily intraperitoneally via cancer spheroids. Podocalyxin (PODXL), an anti-adhesive transmembrane protein, has been reported to promote cancer survival against chemotherapy, however its role in HGSC chemoresistance is unclear. This study investigated whether PODXL plays a role in promoting chemoresistance of HGSC spheroids. We first showed that PODXL was expressed variably in HGSC patient tissues (n = 17) as well as in ovarian cancer cell lines (n = 28) that are more likely categorised as HGSC. We next demonstrated that PODXL-knockout (KO) cells proliferated more slowly, formed less compact spheroids and were more fragile than control cells. Furthermore, when treated with carboplatin and examined for post-treatment recovery, PODXL-KO spheroids showed significantly poorer cell viability, lower number of live cells, and less Ki-67 staining than controls. A similar trend was also observed in ascites-derived primary HGSC cells (n = 6)—spheroids expressing lower PODXL formed looser spheroids, were more vulnerable to fragmentation and more sensitive to carboplatin than spheroids with higher PODXL. Our studies thus suggests that PODXL plays an important role in promoting the formation of compact/hardy HGSC spheroids which are more resilient to chemotherapy drugs; these characteristics may contribute to the chemoresistant nature of HGSC.

Методы сохранения фертильности у больных с серозными пограничными опухолями яичников

Over the past decades, there have been great advances in the understanding of serous borderline tumors of the ovary. Although most serous borderline tumors have a favorable outcome, recurrence and progression to carcinoma are possible. Serous borderline tumor of the ovaries is the most common among all borderline tumors. They are an intermediate group between benign and malignant formations. Most often, serous borderline tumors have a favorable outcome, but there are also cases of relapse and progression to malignancy. In this review, we will try to clarify what a serous borderline tumor is.

Global epidemiology of epithelial ovarian cancer.

Globally, ovarian cancer is the eighth most common cancer in women, accounting for an estimated 3.7% of cases and 4.7% of cancer deaths in 2020. Until the early 2000s, age-standardized incidence was highest in northern Europe and North America, but this trend has changed; incidence is now declining in these regions and increasing in parts of eastern Europe and Asia. Ovarian cancer is a very heterogeneous disease and, even among the most common type, namely epithelial ovarian cancer, five major clinically and genetically distinct histotypes exist. Most high-grade serous ovarian carcinomas are now recognized to originate in the fimbrial ends of the fallopian tube. This knowledge has led to more cancers being coded as fallopian tube in origin, which probably explains some of the apparent declines in ovarian cancer incidence, particularly in high-income countries; however, it also suggests that opportunistic salpingectomy offers an important opportunity for prevention. The five histotypes share several reproductive and hormonal risk factors, although differences also exist. In this Review, we summarize the epidemiology of this complex disease, comparing the different histotypes, and consider the potential for prevention. We also discuss how changes in the prevalence of risk and protective factors might have contributed to the observed changes in incidence and what this might mean for incidence in the future.

Metastasis of serous ovarian carcinoma to the breast: a case report and review of the literature

BackgroundBreast metastasis from primary ovarian cancer is rare, with an estimated frequency of 0.07%. More than 110 cases are reported in the literature of metastatic spread of ovarian cancer to the breast and axilla. This entity usually represents aggressive late disease characterized by multi-drug chemoresistance and a poor prognosis with a median survival time of 16 months. Currently no standardized treatment protocol exists for this condition.Case presentationWe present a case of a 59-year-old Caucasian female with recurrent high-grade serous ovarian cancer who was diagnosed with symptomatic unilateral breast metastasis while on fourth line chemotherapy with weekly paclitaxel. She was treated with local radiation with 2300 cGy to the right breast with a complete response. She then had a subsequent recurrence in the ipsilateral breast 8 months after completion of post treatment imaging. She remains alive to date approximately 2 years after her initial diagnosis of breast metastasis on seventh line treatment.ConclusionsBreast metastasis from primary ovarian cancer is rare and represents advanced disease characterized by multi-drug chemoresistance and a poor prognosis. This case describes radiation therapy as a safe, effective treatment option to improve local control and quality of life in these patients, but with limited durability of response.

A Deep Learning–Based Assessment Pipeline for Intraepithelial and Stromal Tumor-Infiltrating Lymphocytes in High-Grade Serous Ovarian Carcinoma

Tumor-infiltrating lymphocytes (TILs) are associated with improved survival in patients with epithelial ovarian cancer. However, the evaluation of TILs has not been applied to routine clinical practice due to reproducibility issues. We developed two convolutional neural network models to detect TILs and to determine their spatial location in whole-slide images, and established a spatial assessment pipeline to objectively quantify intraepithelial and stromal TILs in patients with high-grade serous ovarian carcinoma. The predictions of the established models showed a significant positive correlation with the number of CD8+ T cells and immune gene expressions. We demonstrated that patients with a higher density of intraepithelial TILs had a significantly prolonged overall survival (OS) and progression-free survival (PFS) in multiple cohorts. Based on the density of intraepithelial and stromal TILs, we classified patients into three immunophenotypes: immune-inflamed, excluded, and desert. The immune-desert subgroup showed the worst prognosis. Gene expression analysis showed that the immune-desert subgroup had lower immune cytolytic activity (CYT) and T-cell-inflamed gene-expression profile (GEP) scores, whereas immune-excluded subgroup had higher expression of interferon-γ and programmed death 1 receptor (PD-1) signaling pathway. Our established evaluation method provides detailed and comprehensive quantification of intraepithelial and stromal TILs throughout hematoxylin and eosin (H&E)-stained slides, and has potential for clinical application for personalized treatment of patients with ovarian cancer.

Integrated analysis of scRNA-seq and bulk RNA-seq identifies FBXO2 as a candidate biomarker associated with chemoresistance in HGSOC

BackgroundHigh-grade serous ovarian carcinoma (HGSOC) is the most prevalent and aggressive histological subtype of epithelial ovarian cancer. Around 80% of individuals will experience a recurrence within five years because of resistance to chemotherapy, despite initially responding well to platinum-based treatment. Biomarkers associated with chemoresistance are desperately needed in clinical practice. MethodsWe jointly analyzed the transcriptomic profiles of single-cell and bulk datasets of HGSOC to identify cell types associated with chemoresistance. Copy number variation (CNV) inference was performed to identify malignant cells. We subsequently analyzed the expression of candidate biomarkers and their relationship with patients' prognosis. The enrichment analysis and potential biological function of candidate biomarkers were explored. Then, we validated the candidate biomarker using in vitro experiments. ResultsWe identified 8871 malignant epithelial cells in a single-cell RNA sequencing dataset, of which 861 cells were associated with chemoresistance. Among these malignant epithelial cells, FBXO2 (F-box protein 2) is highly expressed in cells related to chemoresistance. Moreover, FBXO2 expression was found to be higher in epithelial cells from chemoresistance samples compared to those from chemosensitivity samples in a separate single-cell RNA sequencing dataset. Patients exhibiting elevated levels of FBXO2 experienced poorer outcomes in terms of both overall survival (OS) and progression-free survival (PFS). FBXO2 could impact chemoresistance by influencing the PI3K-Akt signaling pathway, focal adhesion, and ECM-receptor interactions and regulating tumorigenesis. The 50% maximum inhibitory concentration (IC50) of cisplatin decreased in A2780 and SKOV3 ovarian carcinoma cell lines with silenced FBXO2 during an in vitro experiment. ConclusionsWe determined that FBXO2 is a potential biomarker linked to chemoresistance in HGSOC by combining single-cell RNA-seq and bulk RNA-seq dataset. Our results suggest that FBXO2 could serve as a valuable prognostic marker and potential target for drug development in HGSOC.

Metabolomic Analysis of Amino Acid and Organic Acid Profiles in Tissue From Ovarian Cancer Patients Using High-Performance Liquid Chromatography-Tandem Mass Spectrometry (HPLC-MS/MS) and Gas Chromatography-Tandem Mass Spectrometry (GC-MS/MS)

Targeted metabolomics studies on organic acids (OAs) and amino acids (AAs) were performed to search for biomarkers for ovarian cancer progression. Simultaneous AA profiling analysis method was developed through LC-MS/MS. Under optimal conditions, method showed good linearity (r ≥ 0.998) with limits of detection (LOD) ≤ 0.22 ng/mL and limits of quantification (LOQ) of ≤0.72 ng/mL. Repeatability varied from 1.4 to 17.3 relative standard deviation (%RSD) and accuracy varied from −20.6% to 12.1% relative error (% RE). Twenty-six AAs and 13 OAs were detected in the analyses of ovarian tissue from patients with benign ovarian tumors (BOT), borderline tumors (BT), and ovarian serous carcinoma (OSC). Star pattern recognition analysis was performed by normalizing each group to the BOT group. The star symbol plots in the BT and OSC groups were distinct and easily distinguished from those in the BOT group. The BT and the OSC groups exhibited higher 3-hydroxybutyric acid and lactic acid levels, lower pyruvic acid and OA levels in the TCA cycle, and alterations in AA metabolic patterns in comparison to the BOT group. Especially, citrulline and leucine were significantly reduced, while fumaric acid and malic acid significantly increased in the OSC group compared to the BT group. The BT and the OSC groups were completely separated in orthogonal partial least squares-discriminant analysis (OPLS-DA) and heatmap analysis. These findings, elevated ketone body levels, increased anaerobic glycolysis, reduced energy production related to mitochondrial dysfunction in the TCA cycle, and AA metabolic patterns associated with the impaired antioxidant system, may explain the characteristic metabolic reprogramming and Warburg effect related to the progression of the OSC into malignancy.

Prediction of homologous recombination deficiency from Oncomine Comprehensive Assay Plus correlating with SOPHiA DDM HRD Solution.

Poly(ADP-ribose) polymerase (PARP) inhibitors are used for targeted therapy for ovarian cancer with homologous recombination deficiency (HRD). In this study, we aimed to develop a homologous recombination deficiency prediction model to predict the genomic integrity (GI) index of the SOPHiA DDM HRD Solution from the Oncomine Comprehensive Assay (OCA) Plus. We also tried to a find cut-off value of the genomic instability metric (GIM) of the OCA Plus that correlates with the GI index of the SOPHiA DDM HRD Solution. We included 87 cases with high-grade ovarian serous carcinoma from five tertiary referral hospitals in Republic of Korea. We developed an HRD prediction model to predict the GI index of the SOPHiA DDM HRD Solution. As predictor variables in the model, we used the HRD score, which included percent loss of heterozygosity (%LOH), percent telomeric allelic imbalance (%TAI), percent large-scale state transitions (%LST), and the genomic instability metric (GIM). To build the model, we employed a penalized logistic regression technique. The final model equation is -21.77 + 0.200 × GIM + 0.102 × %LOH + 0.037 × %TAI + 0.261 × %LST. To improve the performance of the prediction model, we added a borderline result category to the GI results. The accuracy of our HRD status prediction model was 0.958 for the test set. The accuracy of HRD status using GIM with a cut-off value of 16 was 0.911. The Oncomine Comprehensive Assay Plus provides a reliable biomarker for homologous recombination deficiency.

Abstract 4940: Unraveling ctDNA features in high-grade serous ovarian carcinoma and insights from genomic and transcriptomic integration

Abstract High-grade serous carcinoma (HGSC) is often diagnosed at advanced stages with less than 40% of patients surviving for five years after diagnosis. Circulating tumor DNA (ctDNA) is a minimally invasive technology that can provide crucial insights into tumor biology. Unique features from ctDNA, fragment patterns and nucleosome footprints at transcription start sites (TSS), complement genomic variants. Our study explored ctDNA features in HGSC, integrating with tumor biopsies' genomic and transcriptomic profiles. We focus on two aspects in HGSC: understanding how ctDNA features assist genomic profiling and track dynamic changes during treatment and exploring the biological factors impacting ctDNA release. We used 500+ longitudinal plasma and 400+ pretreatment tissue samples from HGSC patients in the DECIDER study (NCT04846933). Shallow whole-genome sequencing (sWGS) with 0.4x average coverage was conducted on plasma. Integration of DNA and RNA pretreatment tissue data was performed for 98 and 91 patients with available plasma before treatment, respectively. Plasma samples underwent analysis for fragment patterns and TSS signals. Somatic mutations and mutational signatures were retrieved for patients with available WGS tissue data. Pathway enrichment analysis was applied to diverse gene expression profiles. WGS data from 29 healthy individuals (Zhu, G. et al. (2023)) served as controls. DNA fragment profiles and TSS signals distinguish ctDNA from healthy samples. The ability to cluster sample phases based on ctDNA features facilitates tracking longitudinal changes. Integrating tissue DNA and RNA data reveals a positive correlation between high ctDNA release and mutational burden, single-base substitution signature SBS1 as a marker for cell division/mitotic clock and doublet-base substitution signatures linked to late replication. These mechanisms help explain why high ctDNA release group (n=40) is associated with a shorter progression-free survival. Additionally, transcriptomics data indicates associations with proliferation pathways in cancer cells and ctDNA release. The concordance in results from DNA and RNA points to a higher proliferation rate in patients with high ctDNA release, suggesting the need for alternative treatment compared to those with low ctDNA release. In conclusion, our results provide a multifaceted perspective on ctDNA in HGSC. The identification of longitudinal ctDNA features signifies the capability to stratify sample states and show the potential findings through fragment profiles and the discernment of key TSS regions. The proposed aetiologies and enriched pathways associated with ctDNA release, mutation burden and proliferation, shed light on potential treatment avenues. These findings contribute to our understanding of ctDNA in HGSC and offer insights for personalized treatment strategies and monitoring approaches. Citation Format: Mai TN Nguyen, Jaana Oikkonen, Yilin Li, Daria Afentave, Johanna Hynninen, Sampsa K. Hautaniemi. Unraveling ctDNA features in high-grade serous ovarian carcinoma and insights from genomic and transcriptomic integration [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 4940.

Abstract 2418: Copy number variation status of DNA in extracellular vesicles as novel biomarkers of high-grade serous ovarian carcinoma

Abstract Objective: Ovarian cancer is a gynecologic malignancy with a dismal prognosis due to the lack of accurate methods for early diagnosis methods and effective therapies. High-grade serous ovarian carcinoma (HGSOC) is the most common subtype and copy number variations (CNVs) are the dominant genomic events in HGSOC. Extracellular vesicles (EVs) circulate in body fluids and carry pathological genomic information positively. In this study, we evaluated the significance of EV-DNA as novel biomarkers for HGSOC patients. Methods: A total of 124 samples from HGSOC patients and cell lines were analyzed. EVs were isolated using the ultracentrifuge method. Comprehensive CNV statuses were analyzed by whole genome sequencing (WGS) and SNP array. In reference to the Ovarian Cancer Moon Shot database, 30 dominant CNVs in HGSOC were selected as dominant targets for analysis by droplet digital PCR (ddPCR). For predicting the response to PARP inhibitors, HGSOC patients who were treated with olaparib were collected, and DNA was extracted from FFPE tissue at the time of surgery. Results: NTA assays and cryo-electron microscopic analyses showed that the EVs were successfully isolated from all samples. Both WGS and SNP arrays detected correlating CNVs in cell-DNA and EV-DNA for cell lines, and in tissue-DNA and EV-DNA in ascites for patients. The CNV status was also accurately measured by ddPCR. Copy numbers of RAD51, BRCA1, AKT2, CCNE1, and MSH6 were significantly higher in malignant tissue than in benign tissue (p&amp;lt;0.0001, p&amp;lt;0.0001, p=0.0012, p=0.002. p=0.0328, respectively), and were detectable in EV-DNA from ascites. Additionally, the amount of DNA in malignant ascites was significantly higher than in benign ascites (p=0.016), and increased DNA in ascites itself suggested the presence of malignancy. Furthermore, EV-DNA more accurately reflected the CNV status of tumor DNA than cell-free DNA in ascites. Regarding the prediction of PARP inhibitor response, the CNV status in EV-DNA from patients who were treated with olaparib, a PARP inhibitor, demonstrated a marked difference between responders and non-responders. The equation calculated based on the combination of six genes (RB1, GABRA6, CTNNB1, MYC, RAD51, BARD1) could predict the response to olaparib (AUC: 1.0). The selected genes were validated in vitro using EV-DNA, and responders could be identified using the prediction equation calculated from CNV status of the selected genes in EV-DNA from ascites. Conclusion: CNV status of EV-DNA was correctly evaluated and can serve as novel diagnostic and prognostic biomarkers for HGSOC. Citation Format: Ryosuke Uekusa, Akira Yokoi, Kosuke Yoshida, Juntaro Matsuazki, Yusuke Yamamoto, Hiroaki Kajiyama. Copy number variation status of DNA in extracellular vesicles as novel biomarkers of high-grade serous ovarian carcinoma [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 2418.

Abstract 6166: A whole-organ ex vivo optical imaging technique for non-destructive, more precise identification of serous tubal intraepithelial carcinoma (STIC) in fallopian tubes

Abstract Objective With the recent discovery of the fallopian tube (FT) origin of the most common and lethal type of ovarian cancer, high grade serous cancer (HGSC), engineering solutions to overcome the limitations of standard histopathology to more reliably identify incipient HGSCs and their serous tubal intraepithelial carcinoma (STIC) precursors are much needed. This investigation tests the potential of whole-organ ex vivo optical imaging of freshly excised FTs to label and sample abnormal tubal epithelium prior to formalin fixation and paraffin embedding for standard histopathology. Methods This investigation prototyped “OVASEEK”, a whole-organ, near-infrared optical imaging platform for identification of STICs. This prospective biospecimen protocol with annotated clinical data was approved by the IRB. Following salpingectomy at the time of hysterectomy for benign indications, FTs from study participants are longitudinally bivalved. Half of the FT is retained for routine evaluation using the Sectioning and Extensively Examining the Fimbriated end (SEE-FIM) protocol by Johns Hopkins gynecologic pathologists (Gyn Path), while the other half is sent overnight in organ transplant media to MIT for imaging on OVASEEK. Hyperspectral “label free” first pass imaging is performed using a series of band-pass filters. Second pass fluorescence imaging is then performed using nanoparticles tagged with anti-LAMC1 antibodies targeting laminin γ1, a known STIC surface marker. Abnormal signal(s) on OVASEEK imaging of the FT epithelium are tattooed with black ink, the tissue is formalin fixed and returned to Gyn Path for serial sectioning. Research findings are reported in an addendum to the formal pathology report in the electronic medical record and discussed with the patient by the gynecologic oncologist co-investigator. Results OVASEEK enabled non-destructive imaging over a wide field-of-view ~ 12×12 cm, with features of interest in the 1,050-1,550 nm range. In this pilot study, OVASEEK identified histopathologic abnormalities missed by standard SEE-FIM in 20% of FTs (n=2 out of 10). In each case, OVASEEK found microscopic (~200 µm) foci of salpingitis, a lymphoplasmacytic infiltrate consistent with inflammation. Performance of serial sectioning and histopathologic examination of the tattooed epithelium yielded this diagnosis. Conclusion Work is ongoing to improve the resolution, speed and sensitivity of OVASEEK for STIC detection. Identification of µm-sized foci of inflammation using OVASEEK is proof-of-principle that whole-organ ex vivo imaging of freshly excised FTs may be an innovation that improves the diagnostic performance of routine histopathology. Accurate and reproducible diagnosis of STIC and concurrent microscopic HGSC is imperative to the understanding of the early pathogenesis of HGSC in clinically actionable ways. Citation Format: Neelkanth M. Bardhan, Vivek Rastogi, Rebecca L. Stone, Angela M. Belcher. A whole-organ ex vivo optical imaging technique for non-destructive, more precise identification of serous tubal intraepithelial carcinoma (STIC) in fallopian tubes [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 6166.

Abstract 7287: High-grade serous ovarian carcinoma detected with TP53 mutation panel and SiMSen-Seq

Abstract Background: Ovarian carcinoma (OC) has the highest mortality among gynecologic malignancies due to absent or unspecific symptoms. The high-grade serous ovarian carcinoma (HGSC) accounts for over 60% of the OC associated deaths. The most frequent genetic aberrations in HGSC are mutations in the TP53 gene, detected in approximately 96% of the tumors. Previous studies have proposed potential diagnostic utility of detecting mutations in circulating tumor DNA (ctDNA) from OC patients. However, the need for diagnostic methods capable of detecting asymptomatic HGSC is unmet. Objectives: The primary aims of this study were to design a screening tool for identification of HGSC and to evaluate the suitability of various clinical specimen types for diagnostic applications. Methods: In this study, we designed a highly sensitive and robust screening tool using the simple, multiplexed, PCR-based barcoding of DNA for sensitive mutation detection using sequencing (SiMSen-Seq) technique for identification of HGSC (n=11) by TP53 mutation profile in various clinical specimen for diagnostic applications. Specimens sampled included primary tumors, ascites, plasma, vaginal samples, and both liquid and solid samples from cyst-, endocervical-, and endometrial origin (n=94). Results: The in-house designed panel amplified 17 regions, encompassing 619 nucleotide positions within the TP53 gene. Pathogenic variants were identified in 10/11 of the primary tumors, with a VAF ≥ 9% (range: 9-91). Preliminary data indicated that all (100%) paired samples obtained corresponding somatic mutations between two or more of the different compartments from the same patient. In total 10/10 ascites-, 16/16 cyst-, 8/8 plasma-, 5/8 vaginal-, 17/22 endocervical-, and 14/19 endometrial samples showed somatic variants at a consensus read depth of 3 and a minimum VAF ≥ 0.1%. Conclusion: The present study suggests that the TP53 mutation panel can identify somatic variants in a variety of non-invasive liquid biopsies. Additionally, the assessment of the TP53 mutation panel exhibits potential for forthcoming clinical utilization as a diagnostic tool. Citation Format: Amanda Olsson Widjaja, Peter Micallef, Benjamin Ulfenborg, Maria Lycke, Ulf Gyllensten, Therese Carlsson, Tobias Österlund, Anders Ståhlberg, Anna Linder, Karin Sundfeldt. High-grade serous ovarian carcinoma detected with TP53 mutation panel and SiMSen-Seq [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 7287.