Low-grade Serous Carcinoma Research Articles

Impressive clinical response following combined BRAF and MEK inhibition in a low-grade serous ovarian carcinoma patient with a BRAF V600E mutation

Introduction: Low-grade serous ovarian cancer (LGSOC) accounting for less than 10% of all serous ovary cancers. The chemoresistance inherent to this type of ovarian cancer narrows the therapeutic options, especially in the recurrent setting. It is thought that the mitogen-activated protein kinase (MAPK) pathway plays a significant role in the pathogenesis of these tumours, and about 2 to 20% of LGSOC harbour a BRAF mutation. 
 Case report: We present a case report of a 58-year-old woman with LGSOC FIGO stage IIIC who presented recurrence of the tumor process after total abdominal hysterectomy and systemic treatment. Thereafter, she underwent molecular profiling, which revealed a BRAF V600E mutation; accordingly, the patient was administered dabrafenib and trametinib combination therapy. The patient noted significant clinical improvement with normalization of CA 125 and radiological partial response. To date, the patient still maintains partial response, with good treatment tolerance and performance status ECOG 0/1 and good quality of life. 
 Conclusions: LGSOC represents the challenge that is managing a rare cancer with scarce therapeutic options. Given the prevalence of BRAF mutations in this type of tumour, it might be relevant to consider genetic testing. It may provide new treatment opportunities for patients with a known chemoresistant tumour, by identifying potential actionable targets and avoid potential toxicities associated with chemotherapy. Here we demonstrate that impressive clinical responses can be achieved in BRAF mutated LGSOC treated with combined BRAF and MEK inhibitor treatment.

Blood Plasma Small Non-Coding RNAs as Diagnostic Molecules for the Progesterone-Receptor-Negative Phenotype of Serous Ovarian Tumors.

The expression level of the progesterone receptor (PGR) plays a crucial role in determining the biological characteristics of serous ovarian carcinoma. Low PGR expression is associated with chemoresistance and a poorer outcome. In this study, our objective was to explore the relationship between tumor progesterone receptor levels and RNA profiles (miRNAs, piwiRNAs, and mRNAs) to understand their biological characteristics and behavior. To achieve this, we employed next-generation sequencing of small non-coding RNAs, quantitative RT-PCR, and immunohistochemistry to analyze both FFPE and frozen tumor samples, as well as blood plasma from patients with benign cystadenoma (BSC), serous borderline tumor (SBT), low-grade serous ovarian carcinoma (LGSOC), and high-grade serous ovarian carcinoma (HGSOC). Our findings revealed significant upregulation of MMP7 and MUC16, along with downregulation of PGR, in LGSOC and HGSOC compared to BSC. We observed significant correlations of PGR expression levels in tumor tissue with the contents of miR-199a-5p, miR-214-3p, miR-424-3p, miR-424-5p, and miR-125b-5p, which potentially target MUC16, MMP7, and MMP9, as well as with the tissue content of miR-16-5p, miR-17-5p, miR-20a-5p, and miR-93-5p, which are associated with the epithelial-mesenchymal transition (EMT) of cells. The levels of EMT-associated miRNAs were significantly correlated with the content of hsa_piR_022437, hsa_piR_009295, hsa_piR_020813, hsa_piR_004307, and hsa_piR_019914 in tumor tissues. We developed two optimal logistic regression models using the quantitation of hsa_piR_020813, miR-16-5p, and hsa_piR_022437 or hsa_piR_004307, hsa_piR_019914, and miR-93-5p in the tumor tissue, which exhibited a significant ability to diagnose the PGR-negative tumor phenotype with 93% sensitivity. Of particular interest, the blood plasma levels of miR-16-5p and hsa_piR_022437 could be used to diagnose the PGR-negative tumor phenotype with 86% sensitivity even before surgery and chemotherapy. This knowledge can help in choosing the most effective treatment strategy for this aggressive type of ovarian cancer, such as neoadjuvant chemotherapy followed by cytoreduction in combination with hyperthermic intraperitoneal chemotherapy and targeted therapy, thus enhancing the treatment's effectiveness and the patient's longevity.

H2Bub1 loss is an early contributor to clear cell ovarian cancer progression.

Epigenetic aberrations, including posttranslational modifications of core histones, are major contributors to cancer. Here, we define the status of histone H2B monoubiquitylation (H2Bub1) in clear cell ovarian carcinoma (CCOC), low-grade serous carcinoma, and endometrioid carcinomas. We report that clear cell carcinomas exhibited profound loss, with nearly all cases showing low or negative H2Bub1 expression. Moreover, we found that H2Bub1 loss occurred in endometriosis and atypical endometriosis, which are established precursors to CCOCs. To examine whether dysregulation of a specific E3 ligase contributes to the loss of H2Bub1, we explored expression of ring finger protein 40 (RNF40), ARID1A, and UBR7 in the same case cohort. Loss of RNF40 was significantly and profoundly correlated with loss of H2Bub1. Using genome-wide DNA methylation profiles of 230 patients with CCOC, we identified hypermethylation of RNF40 in CCOC as a likely mechanism underlying the loss of H2Bub1. Finally, we demonstrated that H2Bub1 depletion promoted cell proliferation and clonogenicity in an endometriosis cell line. Collectively, our results indicate that H2Bub1 plays a tumor-suppressive role in CCOCs and that its loss contributes to disease progression.

Uptake and Outcomes of Neoadjuvant Chemotherapy Among US Patients With Less Common Epithelial Ovarian Carcinomas

ImportanceRandomized clinical trials examining the effectiveness of neoadjuvant chemotherapy (NACT) for advanced ovarian cancer predominantly included patients with high-grade serous carcinomas. The use and outcomes of NACT in less common epithelial carcinomas are understudied.ObjectiveTo investigate the uptake and survival outcomes in treatment with NACT for less common histologic subtypes of epithelial ovarian cancer.Design, Setting, and ParticipantsA retrospective cohort study and systematic literature review with meta-analysis was conducted using the National Cancer Database from 2006 to 2017 and the National Cancer Institute’s Surveillance, Epidemiology, and End Results Program from 2006 to 2019. Data analysis was performed from July 2022 to April 2023. The evaluation included patients with stage III to IV ovarian cancer with clear cell, mucinous, or low-grade serous histologic subtypes who received multimodal treatment with surgery and chemotherapy.ExposuresExposure assignment per the sequence of treatment: primary debulking surgery (PDS) followed by chemotherapy (PDS group) or NACT followed by interval surgery (NACT group).Main Outcomes and MeasuresTemporal trends and characteristics of NACT use were assessed using multivariable analysis, and overall survival (OS) was assessed with the inverse probability of treatment weighting propensity score.ResultsA total of 3880 patients were examined in the National Cancer Database including 1829 women (median age, 56 [IQR, 49-63] years) with clear cell, 1156 women (median age, 53 [IQR, 42-64] years) with low-grade serous, and 895 women (median age, 57 [IQR, 48-66] years) with mucinous carcinomas. NACT use increased in patients with clear cell (from 10.2% to 16.2%, 58.8% relative increase; P < .001 for trend) or low-grade serous (from 7.7% to 14.2%, 84.4% relative increase; P = .007 for trend) carcinoma during the study period. This association remained consistent in multivariable analysis. NACT use also increased, but nonsignificantly, in mucinous carcinomas (from 8.6% to 13.9%, 61.6% relative increase; P = .07 for trend). Across the 3 histologic subtypes, older age and stage IV disease were independently associated with NACT use. In a propensity score–weighted model, the NACT and PDS groups had comparable OS for clear cell (4-year rates, 31.4% vs 37.7%; hazard ratio [HR], 1.12; 95% CI, 0.95-1.33) and mucinous (27.0% vs 26.7%; HR, 0.90; 95% CI, 0.68-1.19) carcinomas. For patients with low-grade serous carcinoma, NACT was associated with decreased OS compared with PDS (4-year rates, 56.4% vs 81.0%; HR, 2.12; 95% CI, 1.55-2.90). Increasing NACT use and histologic subtype–specific survival association were also found in the Surveillance, Epidemiology, and End Results Program cohort (n = 1447). A meta-analysis of 4 studies, including the current study, observed similar OS associations for clear cell (HR, 1.13; 95% CI, 0.96-1.34; 2 studies), mucinous (HR, 0.93; 95% CI, 0.71-1.21; 2 studies), and low-grade serous (HR, 2.11; 95% CI, 1.63-2.74; 3 studies) carcinomas.Conclusions and RelevanceDespite the lack of data on outcomes of NACT among patients with less common carcinomas, this study noted that NACT use for advanced disease has gradually increased in the US. Primary chemotherapy for advanced-stage, low-grade serous ovarian cancer may be associated with worse survival compared with PDS.

Neuroendocrine Marker Expression in Primary Non-neuroendocrine Epithelial Tumors of the Ovary: A Study of 551 Cases.

Expression of neuroendocrine (NE) markers in primary ovarian non-NE epithelial tumors has rarely been evaluated. The aim of our study was to evaluate the expression of the most widely used NE markers in these neoplasms and to determine any prognostic significance of NE marker expression. The cohort consisted of 551 primary ovarian tumors, including serous borderline tumors, low-grade serous carcinomas, high-grade serous carcinomas (HGSC), clear cell carcinomas, endometroid carcinomas, mucinous borderline tumors, and mucinous carcinomas. Immunohistochemical analysis was performed using antibodies against INSM1, synaptophysin, chromogranin, and CD56 on tissue microarray. Positivity for INSM1, synaptophysin, chromogranin, and CD56 was most frequently observed in mucinous tumors (48.7%, 26.0%, 41.5%, and 100%, respectively). The positivity for these NE markers was mostly restricted to nonmucinous elements distributed throughout the tumor. The mucinous borderline tumor and mucinous carcinomas groups had similar proportions of positivity (mucinous borderline tumor: 53%, mucinous carcinomas: 39%). In the other tumor types, except for HGSC, there was only focal expression (5%-10%) or negativity for NE markers. HGSC showed high CD56 expression (in 26% of cases). Survival analysis was only performed for CD56 in HGSC as this was the only group with sufficient positive cases, and it showed no prognostic significance. Except for mucinous tumors, expression of NE markers in non-NE ovarian epithelial tumors is low. CD56 expression in HGSC occurs frequently but is without diagnostic or prognostic value.

Trends in the use of neoadjuvant chemotherapy for low-grade serous ovarian cancer in the United States

ObjectiveTo describe trends in neoadjuvant chemotherapy (NACT) use for low-grade serous ovarian carcinoma (LGSOC) and to quantify associations between NACT and extent of cytoreductive surgery. MethodsWe identified women treated for stage III or IV serous ovarian cancer in a Commission on Cancer accredited program between January 2004–December 2020. Regression models were developed to evaluate trends in NACT use for LGSOC, to identify factors associated with receipt of NACT, and to quantify associations between NACT and bowel or urinary resection at the time of surgery. Demographic and clinical factors were used for confounder control. ResultsWe observed 3350 patients who received treatment for LGSOC during the study period. The proportion of patients who received NACT increased from 9.5% in 2004 to 25.9% in 2020, corresponding to an annual percent change of 7.2% (95% CI 5.6–8.9). Increasing age (rate ratio (RR) 1.15; 95% CI 1.07–1.24), and stage IV disease (RR 2.66; 95% CI 2.31–3.07) were associated with a higher likelihood of receiving NACT. For patients with high-grade disease, NACT was associated with a decrease in likelihood of bowel or urinary surgery (35.3% versus 23.9%; RR 0.68, 95% CI 0.65–0.71). For LGSOC, NACT was associated with a higher likelihood of these procedures (26.6% versus 32.2%; RR 1.24, 95% CI 1.08–1.42). ConclusionNACT use among patients with LGSOC has increased from 2004 to 2020. While NACT was associated with a lower rate of gastrointestinal and urinary surgery among patients with high-grade disease, patients with LGSOC receiving NACT were more likely to undergo these procedures.

Clinical Observations and Outcomes in Advanced Low-Grade Serous Carcinoma of the Ovary: Case Series from a Tertiary Cancer Center.

Low-grade serous carcinoma (LGSC) is a rare histologic subtype of ovarian cancer. We present detailed management of 15 cases of advanced LGSC from a tertiary cancer center of India. Fifteen cases of advanced LGSC who underwent cytoreductive surgery (CRS) were analyzed from a prospectively maintained database. Baseline demographic characteristics, surgical details, and chemotherapy details were recorded. Descriptive statistics were summarized, and progression-free survival (PFS) and overall survival (OS) were estimated. The median age was 37years. Nine patients had received NACT. All cases were FIGO stage III. Mean PCI was 15. Eleven patients had a completeness of cytoreduction score of 0-1. The median surgical time was 7.5h; nine patients required multiple gastrointestinal resections. Median blood loss was 2500ml. Median postoperative ventilation, ICU stay, and hospital stays were 1, 2, and 16days, respectively. One patient had a grade III complication. Four patients received adjuvant chemotherapy. There was no postoperative mortality at the end of 90days of surgery. All the patients except one were offered hormonal maintenance therapy. At a median follow-up of 43months, 4 patients were disease-free, 9 had a recurrence, one died of disease progression, and one was lost to follow-up. Most recurrences were locoregional in the peritoneal cavity or pelvis. Four-year OS and PFS were 71.8% and 29.7%, respectively. Advanced LGSCs occur mostly in young premenopausal women with favorable oncologic outcomes. Optimal CRS is the mainstay of treatment. Relative chemo-resistance and hormone receptor positivity provide an excellent therapeutic opportunity for endocrine therapy.

Rare Epithelial Ovarian Cancers: Low Grade Serous and Mucinous Carcinomas.

The ovarian epithelial cancer histotypes can be divided into common and rare types. Common types include high-grade serous ovarian carcinomas and the endometriosis-associated cancers, endometrioid and clear-cell carcinomas. The less common histotypes are mucinous and low-grade serous, each comprising less than 10% of all epithelial carcinomas. Although histologically and epidemiologically distinct from each other, these histotypes share some genetic and natural history features that distinguish them from the more common types. In this review, we will consider the similarities and differences of these rare histological types, and the clinical challenges they pose.

The effect of maintenance hormone therapy on overall survival in advanced-stage low-grade serous ovarian carcinoma: A risk-set matched retrospective study.

5568 Background: Low-grade serous ovarian carcinoma (LGSOC) is a rare malignancy often treated similarly to high-grade serous ovarian carcinoma (HGSOC) despite differences in clinical behavior and carcinogenesis. Observational studies suggest that, among patient with advanced-stage LGSOC, maintenance hormonal therapy (HT) following primary treatment is associated with improved progression free survival. We conducted a multi-institutional observational study to investigate whether HT is associated with an overall survival advantage in this setting. Methods: We included patients with histologically confirmed stage III or IV LGSOC diagnosed between Jan 1, 2004, and Dec 31, 2019, treated in Commission on Cancer accredited cancer programs in the US. Patients who received HT within 6 months of diagnosis were matched to controls who did not initiate HT during this timeframe. The primary outcome was risk of death from any cause, within five-years of initiation of HT or observation. For each treated patient, we employed risk-set propensity score matching to identify a control in a manner that avoided the introduction of immortal-time-bias, and balanced groups with respect to year of diagnosis, upfront treatment strategy, age, stage, race/ethnicity, comorbidity index, insurance status, zip-code median income, and cancer program type. Results: There were 296 patients who initiated HT within 6 months of diagnosis, and 2,805 potential controls. Patients who received HT were more often treated in academic medical centers (55% vs 44%), diagnosed later in the study period (62% vs 23% diagnosed in 2018-2019), and received upfront chemotherapy less frequently (55% vs 83%). After risk set and propensity score matching, we identified 204 patients treated with HT and 204 untreated controls, who were otherwise similar with respect to measured covariates. In the matched cohort, maintenance HT was associated with a reduction in the risk of death (hazard ratio 0.61; 95% CI 0.37-0.99), corresponding to a 60-month survival of 71% compared with 61%, and an improvement in 5-year life expectancy of 3.6 months (95% CI 0.004-7.2). Conclusions: Maintenance hormone therapy following primary management of LGSOC is associated with an overall survival benefit compared with observation.

A DMBA-induced ovarian cancer model: Could it be clinically useful to test OncoTherad and erythropoietin as anticancer approaches?

e17589 Background: The term ovarian carcinoma (OC) refers to a heterogeneous collection of five distinct diseases known as histotypes. While histotype-specific treatment is still a clinical challenge, well-characterized models are required for testing new therapies. OncoTherad is a nanoimmunotherapy developed by University of Campinas/Brazil, which exhibits antitumor properties. Erythropoietin (EPO) has cytoprotective effects including in the ovaries. We assessed whether a chemically-induced animal OC model was representative of human disease by evaluating which histotype it best represents. We evaluated both mutational and immunohistochemical (IHC) biomarkers routinely used for human OC and used the observed features to provide context in the evaluation of OncoTherad and EPO effects. Methods: Thirty-five Fischer rats were distributed into 5 groups: Control (Sham surgery); Cancer (7,12-dimethylbenzoanthracene – DMBA injection in the ovarian bursa, 1.25 mg/kg); OncoTherad (20mg/kg IP); EPO (8.4 µg/kg IP); and OncoTherad+EPO (same doses). Ovary specimens were formalin-fixed into paraffin-embedded donor blocks. After DNA extraction and tissue microarray construction, we assessed typical gene mutations directly by Sanger sequencing (Pik3ca, Ctnnb1, and Kras) or indirectly using IHC surrogates (Arid1a and p53). Finally, we examined biomarkers typical of different OC histotypes (Wt1, Pr, Hnf1β) as well as lymphocyte density (CD3) by IHC. Results: The results were consistent across the cancer-induced animals. The majority of abnormal epithelial cells were Wt1+, Pr-, and Hnf1b-. Therefore, our rat model of DMBA-induced ovarian cancer was most likely serous type ovarian carcinoma, in agreement with the histopathological analysis. The ovarian lesions were molecularly similar to low-grade serous ovarian carcinoma as abnormal pattern of p53 staining was rarely observed. Loss of immunoreactivity for Arid1a protein was seen in some abnormal epithelium. However, the interpretability of mutation surrogates in rat tissues may not always be consistent with IHC analysis systems applied for human tissues. Furthermore, DNA sequencing did not reveal driver mutations in any of the sampled specimens. The treatments, especially OncoTherad+EPO, increased the number of CD3 positive immune cells. After EPO treatment, the tumor and abnormal areas showed a higher number of CD3+ lymphocytes than the normal regions; following a previous work, this could be due to substantial presence of Foxp3 positive cells. Conclusions: The features analyzed favored a low-grade serous carcinoma model in which treatments with OncoTherad and EPO showed immunomodulatory properties related to the reduction of ovarian lesions seen in previous work. The overall data highlight the importance of further characterizations of animal models to provide a complete and specific panel for testing new drugs.

Cytopathological characterization of ascites for the diagnosis of serous ovarian carcinoma

Objective: To investigate the cytomorphological and immunocytochemical features of tumor cells in the ascites of ovarian plasmacytoma (SOC). Methods: Specimens of serous cavity effusions were collected from 61 tumor patients admitted to the Affiliated Wuxi People's Hospital of Nanjing Medical University from January 2015 to July 2021, including ascites from 32 SOC, 10 gastrointestinal adenocarcinomas, 5 pancreatic ductal adenocarcinomas, 6 lung adenocarcinomas, 4 benign mesothelial hyperplasia and 1 malignant mesothelioma patients, pleural effusions from 2 malignant mesothelioma patients and pericardial effusion from 1 malignant mesothelioma. Serous cavity effusion samples of all patients were collected, conventional smears were made through centrifugation, and cell paraffin blocks were made through centrifugation of remaining effusion samples. Conventional HE staining and immunocytochemical staining were applied to observe and summarize cytomorphological characteristics and immunocytochemical characteristics. The levels of serum tumor markers carbohydrate antigen 125 (CA125), carcinoembryonic antigen (CEA) and carbohydrate antigen 19-9 (CA19-9) were detected. Results: Of the 32 SOC patients, 5 had low-grade serous ovarian carcinoma (LGSOC) and 27 had high-grade serous ovarian carcinoma (HGSOC). 29 (90.6%) SOC patients had elevated serum CA125, but the difference was not statistically significant between them and patients with non-ovarian primary lesions included in the study (P>0.05); The serum CEA was positive in 9 patients with gastrointestinal adenocarcinoma and 5 patients with lung adenocarcinoma, and the positive rate was higher than that in SOC patients (P<0.001); The serum CA19-9 was positive in 5 patients with gastrointestinal adenocarcinoma and 5 patients with pancreatic ductal adenocarcinoma, and the positive rate was higher than that in SOC patients (P<0.05). The serum CA125, CEA and CA19-9 were within the normal range in 4 patients with benign mesothelial hyperplasia. LGSOC tumor cells were less heterogeneous and aggregated into small clusters or papillary pattern, and psammoma bodies could be observed in some LGSOC cases. The background cells were fewer and lymphocytes were predominant; the papillary structure was more obvious after making cell wax blocks. HGSOC tumor cells were highly heterogeneous, with significantly enlarged nuclei and varying sizes, which could be more than 3-fold different, and nucleoli and nuclear schizophrenia could be observed in some cases; tumor cells were mostly clustered into nested clusters, papillae and prune shapes; there were more background cells, mainly histiocytes. Immunocytochemical staining showed that AE1/AE3, CK7, PAX-8, CA125, and WT1 were diffusely positively expressed in 32 SOC cases. P53 was focally positive in all 5 LGSOCs, diffusely positive in 23 HGSOCs, and negative in the other 4 HGSOCs. Most of adenocarcinomas of the gastrointestinal tract and lung had a history of surgery, and tumor cells of pancreatic ductal adenocarcinoma tend to form small cell nests. Immunocytochemistry can assist in the differential diagnosis of mesothelial-derived lesions with characteristic "open window" phenomenon. Conclusion: Combining the clinical manifestations of the patient, the morphological characteristics of the cells in the smear and cell block of the ascites can provide important clues for the diagnosis of SOC, and the immunocytochemical tests can further improve the accuracy of the diagnosis.

SOX17 is a highly sensitive and specific marker for metastatic ovarian and endometrial carcinomas in cytology cell block specimens.

SOX17 (SRY-box transcription factor 17) was recently identified as a highly sensitive and specific marker for ovarian and endometrial carcinomas in surgical specimens. In this study, validation of the utility of SOX17 immunohistochemistry (IHC) in diagnosing metastatic gynecologic carcinomas in cytology specimens was sought. The study cohort included 84 cases of metastatic carcinomas that included 29 metastatic gynecologic carcinomas (24 ovarian high-grade serous carcinomas, two endometrial serous carcinomas, one low-grade serous carcinoma, one ovarian clear cell carcinoma, and one endometrial endometrioid carcinoma) and 55 cases of metastatic nongynecologic carcinomas (10 clear cell renal cell carcinomas, 10 papillary thyroid carcinomas, 11 gastrointestinal adenocarcinomas, 10 breast carcinomas, 10 lung adenocarcinomas, and four urothelial carcinomas). Cytology specimen types included peritoneal fluid (n=44), pleural fluid (n=25), and fine-needle aspiration (n=15). SOX17 IHC was performed on the cell block sections. The intensity of staining and percent positivity of the tumor cells were evaluated. SOX17 was highly expressed in all tested metastatic gynecologic carcinomas with diffuse and strong nuclear expression (29 of 29; 100%). SOX17 was negative in other metastatic nongynecologic carcinomas (54 of 55; 98.18%) except for one papillary thyroid carcinoma that showed low positivity (<10%). SOX17 is a highly sensitive (100%) and specific (98.2%) marker for the differential diagnosis of metastatic gynecologic carcinomas in cytology specimens. Therefore, SOX17 IHC should be included in the workup of differential diagnosis of metastatic gynecologic carcinomas in cytology specimens.

Whole exome sequencing of low grade serous ovarian carcinoma identifies genomic events associated with clinical outcome

ObjectivesLow-grade serous ovarian carcinoma (LGSOC) is a distinct, rare, ovarian cancer type characterised by younger patient age and intrinsic chemoresistance. Understanding the molecular landscape is crucial for optimising targeted therapy. MethodsGenomic data from whole exome sequencing of tumour tissue was analysed in a LGSOC cohort with detailed clinical annotation. Results63 cases were analysed and three subgroups identified based on single nucleotide variants: canonical MAPK mutant (cMAPKm: 52%, KRAS/BRAF/NRAS), MAPK-associated gene mutation (MAPK-assoc: 27%) and MAPK wild-type (MAPKwt: 21%). NOTCH pathway disruption occurred across all subgroups. Tumour mutational burden (TMB), mutational signatures and recurrent copy number (CN) changes varied across the cohort with co-occurrence of chromosome 1p loss and 1q gain (CN Chr1pq) a recurrent feature. Low TMB and CN Chr1pq were associated with inferior disease-specific survival (HR 6.43; p < 0.001 and HR 3.29, p = 0.011 respectively). Stepwise genomic classification in relation to outcome resulted in four groups (TMB low; CN Chr1pq; MAPKwt/MAPKassoc; cMAPKm). 5 year disease-specific survival was 46%, 55%, 79% and 100% respectively for these groups. The two most favourable genomic subgroups were enriched for the SBS10b mutational signature, particularly the cMAPKm subgroup. ConclusionsLGSOC comprises multiple genomic subgroups with distinct clinical and molecular features. Chr1pq CN arm disruption and TMB represent promising methods to identify individuals with poorer prognosis. Further investigation of the molecular basis for these observations is required. MAPKwt cases represent around a fifth of patients. NOTCH inhibitors represent a candidate therapeutic strategy worthy of exploration across these cases.

Distinct histopathological features are associated with molecular subtypes and outcome in low grade serous ovarian carcinoma

Low grade serous ovarian carcinoma (LGSOC) demonstrates unique clinical and molecular features compared to other ovarian cancer types. The relationship between common histological features of LGSOC and molecular events, such as hormone receptor expression patterns and MAPK gene mutation status, remains poorly understood. Recent data suggest some of these molecular features may be biomarkers of response to recently introduced biologically-targeted therapies, namely endocrine therapy and MEK inhibitors. We utilize a cohort of 63 pathologically-confirmed LGSOC cases with whole exome sequencing and hormone receptor expression data to investigate these relationships. LGSOC cases demonstrated uniformly high oestrogen receptor (ER) expression, but variable progesterone receptor (PR) expression intensity. 60% and 37% of cases demonstrated micropapillary and macropapillary patterns of stromal invasion, respectively. 63% of cases demonstrated desmoplasia, which was significantly associated with advanced disease stage and visible residual disease after cytoreductive surgery. MAPK-mutant cases (KRAS, BRAF, NRAS) more frequently demonstrated macropapillary stromal invasion, while Chr1p loss was associated with desmoplasia and low PR expression. Presence of micropapillary stromal invasion and low PR expression were associated with significantly poorer survival after accounting for stage and residual disease status. Together, these data identify novel relationships between histopathological features and molecularly-defined subgroups in LGSOC.

Deregulated Metabolic Pathways in Ovarian Cancer: Cause and Consequence.

Ovarian cancers are tumors that originate from the different cells of the ovary and account for almost 4% of all the cancers in women globally. More than 30 types of tumors have been identified based on the cellular origins. Epithelial ovarian cancer (EOC) is the most common and lethal type of ovarian cancer which can be further divided into high-grade serous, low-grade serous, endometrioid, clear cell, and mucinous carcinoma. Ovarian carcinogenesis has been long attributed to endometriosis which is a chronic inflammation of the reproductive tract leading to progressive accumulation of mutations. Due to the advent of multi-omics datasets, the consequences of somatic mutations and their role in altered tumor metabolism has been well elucidated. Several oncogenes and tumor suppressor genes have been implicated in the progression of ovarian cancer. In this review, we highlight the genetic alterations undergone by the key oncogenes and tumor suppressor genes responsible for the development of ovarian cancer. We also summarize the role of these oncogenes and tumor suppressor genes and their association with a deregulated network of fatty acid, glycolysis, tricarboxylic acid and amino acid metabolism in ovarian cancers. Identification of genomic and metabolic circuits will be useful in clinical stratification of patients with complex etiologies and in identifying drug targets for personalized therapies against cancer.

The impact of adjuvant antihormonal therapy versus observation on recurrence of borderline ovarian tumors: A retrospective cohort study

ObjectivesAdjuvant management of borderline ovarian tumors (BOT) after surgical diagnosis and staging is not standardized. While many patients undergo observation alone, some providers have introduced the use of adjuvant antihormonal therapy for BOT, extrapolating from studies suggesting improvement in progression-free survival in the low-grade serous ovarian carcinoma population. We hypothesized that adjuvant antihormonal therapy after surgical diagnosis of BOT would improve progression-free survival compared to surveillance alone. MethodsThis is a retrospective review of BOT at one academic institution over thirteen years comparing management with antihormonal therapy, including aromatase inhibitors, progestins, and selective estrogen receptor modulators, to surveillance alone. Patients with concurrent malignancy were excluded. Data were abstracted from electronic medical records. Groups were compared by bivariate statistics. ResultsWe identified 193 patients with BOT. Of these, 17 (8.8%) were treated with adjuvant antihormonal therapy and 24 (12.4%) recurred. Patients treated with antihormonal therapy were more likely to be obese (64.7% vs 37.9%, p = 0.032), have advanced-stage disease (70.6% vs 11.4%, p < 0.001), serous histotype (94.1% vs 59.4%, p = 0.005) or microinvasion (29.4% vs 9.7%, p = 0.030), and less likely to have undergone fertility-sparing surgery (18.8% vs 51.7%, p = 0.012). Use of antihormonal therapy was not associated with a difference in recurrence or survival. ConclusionsThis study is the first retrospective cohort review of adjuvant antihormonal therapy in BOT. We found that adjuvant antihormonal therapy for BOT is not associated with recurrence. While this single institution retrospective cohort study may lack the power to confirm or refute benefit, further studies could evaluate whether a subpopulation exists in whom antihormonal therapy is worthwhile.

Abstract 3402: In vivo efficacy of RAF/MEK clamp avutometinib (VS-6766) in combination with FAK inhibition in low grade serous ovarian cancer

Abstract Objective: Low grade serous carcinoma (LGSC) of the ovary is characterized by a high recurrence rate, resistance to most chemotherapeutic agents, and limited effective therapeutic options. Recently, LGSC has been found to often contain mutations in KRAS (~30%), NRAS (~10%), and BRAF (~8%). Avutometinib (VS-6766) is a RAF/MEK clamp that induces dominant negative complexes of RAF with MEK, and inhibits proliferation of KRAS, NRAS, BRAF, and CRAF mutant cell lines. VS-4718 is a focal adhesion kinase (FAK) inhibitor that has shown synergistic anti-tumor activity with avutometinib in other cancer models, as it blocks the potential of FAK to function as an adaptive resistance mechanism to RAF/MEK inhibition. This study aimed to determine the efficacy of the RAF/MEK clamp avutometinib with FAK inhibition in vivo in LGSC patient derived tumor xenograft (PDX) models. Methods: Whole-exome sequencing was used to evaluate mutations in two primary ovarian LGSC PDX models (OVA(K)250 and PERIT(M)17). OVA(K)250 and PERIT(M)17 cells were injected into SCID mice and animals were treated with either vehicle control (CTRL), RAF/MEK clamp avutometinib (MEKi), FAK inhibitor VS-4718, or the combination (MEKi/FAKi). Tumor volumes were measured twice per week. Results: Both the OVA(K)250 and PERIT(M)17 PDX models express wildtype KRAS and express RAF1 mutations at position 12641679 A&amp;gt;C, V207G. In PDX OVA(K)250 mice treated with MEKi/FAKi, day 9 tumor volume was significantly lower compared to mice treated with CTRL (p=0.0002). At day 9, tumor volume was also significantly lower in mice treated with MEKi alone compared to CTRL (p=0.0007). Mice treated with FAKi alone had tumor volumes that were significantly smaller than CTRL by day 12 (p=0.009). By day 23, CTRL mice had reached tumor volume characteristics requiring sacrifice. Combination MEKi/FAKi treatment resulted in improved overall survival (OS); median OS for combination or MEKi alone was not reached by 60 days. Treatment with FAKi led to median OS of 35 days; CTRL mice had median OS of 23 days (p=0.001). In vivo experiments with PDX PERIT(M)17 and PDX OVA(K)250 are ongoing. Conclusion: Combination of avutometinib with FAK inhibition showed improved in vivo preclinical anti-tumor efficacy relative to either agent alone in an LGSC PDX model with wildtype KRAS and with a RAF1 mutation. These data support an ongoing registration-directed study with avutometinib ± the FAK inhibitor defactinib for patients with recurrent LGSC (NCT04625270). Citation Format: Blair McNamara, Cem Demirkiran, Stefania Bellone, Levent Mutlu, Margherita Zipponi, Miguel S. Verzosa, Justin Harold, Tobias M. Hartwich, Gary Altwerger, Elena Ratner, Gloria Huang, Mitchell Clark, Vaagn Andikyan, Masoud Azodi, Peter E. Schwartz, Peter Dottino, Alessandro D. Santin. In vivo efficacy of RAF/MEK clamp avutometinib (VS-6766) in combination with FAK inhibition in low grade serous ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 3402.

Abstract 6417: Deciphering aberrant STING pathway and exploring oncolytic viruses therapy in low grade serous ovarian carcinoma

Abstract There are two serous ovarian cancer histotypes, low and high grade (LGSOC and HGSOC), which are distinct clinical and biological entities. LGSOC is a rare histotype with a relatively stable genome, while HGSC is more common and genomically unstable. Somewhat surprisingly LGSOC expresses high levels of the stimulator of the interferon genes (STING). The STING pathway recognizes cytoplasmic double-stranded DNA and mounts innate cellular immunity through interferon-beta type I production. Our objective is to investigate the aberrant STING signaling in LGSOC and test the effectiveness of oncolytic viruses against LGSOC. We used immunohistochemistry on tissue microarrays (TMAs) to assess STING protein expression in different ovarian cancer histotypes. Whole proteome analysis was applied to identify differentially expressed proteins in LGSOC and HGSOC patient samples (both n=9). Further, a semi-targeted proteomics approach was used to evaluate the expression levels of the STING pathway-related proteins in LGSOC, HGSOC, and LGSOC precursor tumors (each subtype, n=20). To evaluate the key transcription, phosphorylation, and translocation events in STING signaling, we treated LGSOC cell lines with an agonist (dsDNA90) and performed qPCR, immunoblotting, and immunofluorescence experiments, respectively. We tested the viability of the LGSOC cell lines in response to Vaccinia Virus (VV), and Vesicular Stomatitis Virus (VSV) based oncolytic vectors with or without immunostimulatory transgenes. Our results show that STING protein levels were consistently higher in LGSOC TMAs relative to other histotypes. Proteomics analysis showed that the half of the 16 most differentially expressed proteins were the effectors of STING signaling with unexpectedly lower expression in LGSOC, suggesting that despite the robust levels of STING in LGSOC tumors, the pathway is not fully active. Attenuated STING translocation and expression of IFNB1 and other cytokines in LGSOC cell lines confirm the aberrancy in the STING pathway. Semi-targeted proteomics revealed the considerable overexpression of STIM1 in LGSOC patient tumors, which has previously been shown to sequester STING in the endoplasmic reticulum. The treatment with VV and VSV oncolytic viruses significantly reduced the proliferation of LGSOC cell lines. In summary, we find attenuated STING signaling in LGSOC, possibly due to overexpression of STIM1 preventing STING translocation. Although oncolytic viruses show promising results in LGSOC cell lines, more research is needed to determine the optimal treatment strategy, testing oncolytic viruses expressing various transgenes and combination therapies. Citation Format: Almira Zhantuyakova, Dawn Cochrane, Gian Negri, Sandra E. Spencer Miko, Taha Azad, Jutta Huvila, Marta Llaurado Fernandez, Mark Carey, Gregg B. Morin, John Bell, David Huntsman. Deciphering aberrant STING pathway and exploring oncolytic viruses therapy in low grade serous ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6417.

Abstract 162: Individualizing treatment using patient derived organoids, BH3 profiling and microfluidics: A proof of concept in a patient with low-grade serous ovarian carcinoma

Abstract Background N of 1 treatment paradigms represent the pinnacle of personalized medicine in which a patient’s tumors are profiled to guide treatment. Low-grade serous ovarian cancer (LGSC) is a distinct subtype of ovarian cancer, comprising ~10% of serous carcinomas and typically characterized by a younger age of onset. Molecularly, these tumors are often characterized by alterations within the Ras signaling pathway, including KRAS mutations. Clinically, LGSC is often resistant to standard cytotoxic chemotherapy, but may have sensitivity to hormonal therapy or MEK inhibitors. Here we report on a platform and proof of concept in one LGSC patient to evaluate personalized tumor-directed therapy regimens using patient-derived organoids (PDOs), BH3 profiling and viability evaluation in 3D microfluidic devices. Methods A patient with LGSC presented to the Dana Farber Cancer Institute and was treated with carboplatin and paclitaxel before a total abdominal hysterectomy with a bilateral salpingo-oophorectomy. Tissue was obtained under an IRB approved protocol and PDOs were established. Standard of care and non-standard of care treatments including doxorubicin, abemaciclib, letrozole, alpelisib, tamoxifen, trametinib, venetoclax, and navitoclax were evaluated by two orthogonal assays. First, they were tested for delta priming by BH3 profiling (Bhola et.al., Sci Signal. 2020 ) and second for cell viability using 3D microfluidic devices by TMRM/DRAQ7 dual-color fluorescent staining. Standard of care treatments carboplatin and paclitaxel were evaluated as individual treatments and in combination in 3D microfluidic devices. Results We successfully established a PDO model from the patient’s tumor sample in 14 days. BH3 profiling at 24 hours and viability in 3D microfluidic devices after 6 days in treatment showed that from the eight tested drugs, the model was sensitive to navitoclax and venetoclax. Average percent change in viability was -91.5% and -89.9%, respectively, and the drugs had a dynamic BH3 profiling index of 551.4 AUC (+/- 76.63) and 488.9 AUC (+/- 21.46) with the threshold of response being &amp;gt;175 for BH3 profiling. Trametinib showed a clear response in 3D, with an average percent change of -72.6% compared to the control but no significant response in BH3 profiling. Neither carboplatin and paclitaxel alone, nor in combination, elicited a significant change in viability. This observation was consistent with the patient’s history prior to surgery, where the tumor did not demonstrate significant clinical response to neoadjuvant carboplatin and paclitaxel therapy. Conclusions We describe a proof of concept of a N of 1 response assessment platform for LGSC using PDOs, BH3 profiling and live/dead fluorescent staining in microfluidic devices and demonstrate that BH3 profiling and 3D viability assessment assays show good congruity. Citation Format: Brittany Meisenheimer, Ha V. Vo, Kelley E. McQueeney, Aisha L. Saldanha, Carina Feeney, Courtney H. Qi, Swati Narayan, Jennifer D. Curtis, Marisa R. Nucci, Anthony Letai, Cloud P. Paweletz, Joyce F. Liu, Ursula A. Matulonis, Elena Ivanova. Individualizing treatment using patient derived organoids, BH3 profiling and microfluidics: A proof of concept in a patient with low-grade serous ovarian carcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 162.

Chemotherapy response in low-grade serous ovarian carcinoma at a comprehensive cancer center: Readdressing the roles of platinum and cytotoxic therapies.

Data on platinum sensitivity of low-grade serous ovarian carcinoma (LGSOC) in the upfront setting is lacking, and there is limited and contradictory information on chemotherapy responses in recurrent disease. Patients with LGSOC seen at a comprehensive cancer center from January 1, 1998 to September 30, 2021 were identified from institutional databases. Response to neoadjuvant chemotherapy (NACT) or adjuvant platinum-based chemotherapy and to second- to fifth-line regimens was retrospectively characterized by Response Evaluation Criteria in Solid Tumors (RECIST) v1.1. Wilcoxon rank-sum and two-tailed Fisher exact tests were employed. Of 50 patients, 12 received platinum doublets for suboptimal residual disease and 11 as NACT. Of 12 patients with suboptimal residual disease, seven (58%) achieved objective responses (five partial responses [PRs] and two complete responses); of the 11 patients who underwent NACT, one (9%) achieved a PR (p=.027). The 15 remaining patients had stable disease on first-line platinum chemotherapy. Of 44 patients who recurred, 20 had RECIST-evaluable responses to second-line and 27 to third-line chemotherapy. Objective response rates to platinum-based chemotherapy were 22% (two of nine) in the second line and 10% (one of 10) in the third. In second and third lines, highest response rates were observed with nonplatinum chemotherapy with bevacizumab, at 100% (two of two) and 30% (three of 10), respectively. Primary platinum-based chemotherapy has moderate activity in LGSOC and minimal activity in the recurrent setting, suggesting standard definitions of platinum sensitivity may not apply in LGSOC. In the second and third lines, nonplatinum chemotherapy/bevacizumab elicited the highest response rates.