Ovarian Ascites Research Articles

Folate Receptor Beta as a Direct and Indirect Target for Antibody-Based Cancer Immunotherapy.

Folate receptor beta (FRβ) is a folate binding receptor expressed on myeloid lineage hematopoietic cells. FRβ is commonly expressed at high levels on malignant blasts in patients with acute myeloid leukemia (AML), as well as on M2 polarized tumor-associated macrophages (TAMs) in the tumor microenvironment of many solid tumors. Therefore, FRβ is a potential target for both direct and indirect cancer therapy. We demonstrate that FRβ is expressed in both AML cell lines and patient-derived AML samples and that a high-affinity monoclonal antibody against FRβ (m909) has the ability to cause dose- and expression-dependent ADCC against these cells in vitro. Importantly, we find that administration of m909 has a significant impact on tumor growth in a humanized mouse model of AML. Surprisingly, m909 functions in vivo with and without the infusion of human NK cells as mediators of ADCC, suggesting potential involvement of mouse macrophages as effector cells. We also found that TAMs from primary ovarian ascites samples expressed appreciable levels of FRβ and that m909 has the ability to cause ADCC in these samples. These results indicate that the targeting of FRβ using m909 has the potential to limit the outgrowth of AML in vitro and in vivo. Additionally, m909 causes cytotoxicity to TAMs in the tumor microenvironment of ovarian cancer warranting further investigation of m909 and its derivatives as therapeutic agents in patients with FRβ-expressing cancers.

Severe recurrent ascites in a Pseudo-Meigs’ syndrome variant

Background: Meigs’ syndrome is the triad of ovarian neoplasm, ascites and pleural effusion, while Pseudo-Meigs’ syndrome is the presence of ascites and pleural effusion with other pelvic tumors. Ascites resolves after tumor resection. Our case does not meet classic criteria for either but is likely a variant of Pseudo-Meigs’ syndrome. Case: A 30-year-old female had multiple Emergency Department visits for abdominal pain, distention, and shortness of breath. Imaging showed severe abdominal ascites with a large leiomyomatous uterus but no pleural effusions. Multiple paracenteses revealed benign cytology. After counselling, she underwent an abdominal myomectomy which resolved her recurrent ascites. Conclusion: Variants of Pseudo-Meigs’ syndrome should be considered in the differential of abdominal pain and leiomyomas with ascites, and surgical management should be offered.

Síndrome de pseudo-Meigs por tumor de células de la granulosa

Definimos síndrome de Meigs como la triada de tumor ovárico benigno, derrame pleural y ascitis, una condición clínica rara que se resuelve con la resección del tumor. Estas mismas características pueden presentarse en el síndrome de pseudo-Meigs que se asocia a tumores malignos, que agregan un aumento importante de los niveles del marcador CA-125. Es conocido por muchos años, pero su fisiopatología aún no está clara. Se presenta un caso de síndrome pseudo-Meigs y se hace una breve revisión bibliográfica de sus características más importantes.

Assessing the Usefulness of Severity Markers in Women with Ovarian Hyperstimulation Syndrome.

The present study aims to assess the usefulness of severity markers in women with ovarian hyperstimulation syndrome (OHSS). An observational study was designed including 76 women with varying degrees of severity of OHSS. Clinical history, physical examination, laboratory tests, and ultrasound measurement of the ovarian size and ascites index were carried out in all patients. Intra-abdominal pressure (IAP) was measured using an intravesical Foley Manometer catheter. Ascites index and ovarian volume increased progressively being highest in the most severe stage of OHSS. The median IAP in mild OHSS was found to be lower than that in the moderate and severe OHSS (4.0mm, 12mm, and 16.0mm, respectively). Critical cases of OHSS presented the highest IAP (25.0mm). IAP did not reach the level of intra-abdominal hypertension in mild OHSS, whereas moderate and severe OHSS was associated with intra-abdominal hypertension grade I and grade II-III, respectively. Values of IAP in critical OHSS were found similar to those observed in abdominal compartment syndrome patients. The IAP showed a strong positive correlation with ovarian volume and ascites index. The reduction of IAP after paracentesis was greater among critical OHSS patients. The ovarian volume and the level of intra-abdominal hypertension are related to the severity of OHSS and are of particular importance in the initialization of the syndrome. Ascites index is simple and convenient and can serve as an indirect marker of the abdominal reserve volume. In conjunction with clinical and laboratory data, ascites index and IAP values might be indicators for paracentesis.

Meigs\u2019 syndrome mimicking heart failure with preserved ejection fraction: a case report

BackgroundMeigs’ syndrome is a rare disease characterized by a triad of presentations, including benign ovarian tumor, ascites, and pleural effusion. However, a clinical diagnosis of Meigs’ syndrome remains challenging because pleural and ascitic effusions can be common findings in a variety of underlying conditions. Furthermore, these findings can often be misdiagnosed as pleural and peritoneal dissemination caused by potentially malignant tumors, leading to the administration of improper treatment.Case presentationWe described a case of an 85-year-old postmenopausal female patient with atypical Meigs’ syndrome presenting with right-sided pleural effusion, notable leg edema, and trivial ascites, which was initially mistaken as heart failure with preserved ejection fraction. However, pleural effusion was totally ineffective against diuretic therapy. Subsequently, thoracentesis yielded serosanguineous exudative effusion. Moreover, refractory pleural effusions and abdominal/pelvic computed tomography and magnetic resonance imaging findings strongly suggested bilateral malignant ovarian tumors with pleural dissemination. Repetitive negative cytological results allowed the patient to undergo bilateral salpingo-oophorectomy. Finally, a definitive diagnosis of Meigs’ syndrome was made by confirming the presence of a benign mitotically active cellular fibroma of the ovary by pathology and that pleural effusion resolved following tumor resection.ConclusionsOur case highlights the clinical importance of assessing Meigs’ syndrome in the diagnostic workup of pleural effusion in postmenopausal female patients. Given the favorable prognosis of Meigs’ syndrome, clinicians should consider surgical resection, even with potentially malignant ovarian tumors with accompanying pleural effusion, ascites, or both.

Abstract 3423: CLEC-1 suppress dendritic cell antigen presentation and is a novel myeloid immune checkpoint target for cancer immunotherapy

Abstract Recent literature demonstrates that tumor hijacks physiological mechanisms of C-type lectin receptors (CLRs) that normally restrain immune cell-mediated tissue damage to suppress myeloid cell activation and promotes immune escape. We previously demonstrated that the orphan CLR CLEC-1 expressed by myeloid cells, is enhanced by the immunosuppressive cytokine TGFβ and tempers downstream CD4+ Th1 and Th17 responses following sterile inflammation. Interestingly, we observed a high CLEC-1 expression by human CD11b+ myeloid cells from ovarian ascites and from in-vitro generated pro-tumoral M2 macrophages. Moreover, open-source data show that Clec1a is highly expressed by XCR1-expressing mouse dendritic cells (DC). As these cDC1 are specialized in cross-presentation of dead cell-associated antigens, we evaluated whether CLEC-1 could be a receptor of damaged cells and regulate anti-tumor immunity. Interestingly, we observed that both human and mouse CLEC-1 bind specifically to secondary necrotic cells. No binding was observed with viable, primary necrotic or with early apoptotic cells suggesting that the ligand(s) of CLEC-1 correspond(s) to Damage-Associated Molecular Pattern(s) induced by the cell death process. Then, to test if CLEC-1 in DCs influences cross-presentation of dead cell-associated antigens, we immunized WT and Clec1a KO mice with OVA-loaded dead cells and co-injected OVA-specific TCR transgenic CD8+ OT-I T cells. Impressively, we observed an increased proliferation of CD8+ T cells in the absence of CLEC-1, demonstrating that CLEC-1 in DCs tempers cross-presentation of dead cell-associated antigens. Interestingly, we observed in a model of subcutaneous MC38 colon carcinoma that the combination of the absence of CLEC-1 with cytotoxic and immunogenic chemotherapy (cyclophosphamide), reduces significantly the tumor growth and cures most of the mice. Similarly, in orthotopic models of mesothelioma (AK7) or hepatocarcinoma (Hepa1.6), we observed a prolongation of survival of Clec1a KO mice. Mechanistically, this was associated with an increase of effector CD69+ and of central memory CD44hi CD62Lhi CCR7hi CD4+ and CD8+ T cells in both liver and spleen. Furthermore, we observed a decrease in myeloid-derived suppressor cells. Besides, macrophages display a more mature phenotype relative to MHC class II expression. In addition, transcriptomics analysis performed in tumor-bearing liver of Clec1a KO mice revealed a profound decrease in CSF1 expression suggesting a defect in immunosuppressive myeloid cell recruitment. Moreover, we observed an increase in CCL17 and CCL7 expression, both known to activate CD8+ T cells through DCs and to enhance anti-tumor immunity. Taken together, these results suggest that CLEC-1 in DCs by acting as sensor of cell damage tempers immune response and represents a novel pharmacological target for cancer immunotherapy. Citation Format: Marion Drouin, Javier Saenz, Bérangère Evrard, Vanessa Gauttier, Géraldine Teppaz, Maria-Dolores Lopez-Robles, Cédric Louvet, Nicolas Poirier, Elise Chiffoleau. CLEC-1 suppress dendritic cell antigen presentation and is a novel myeloid immune checkpoint target for cancer immunotherapy [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 3423.

Laparoscopic Resection of a Subserosal Leiomyoma Presenting as Pseudo–Meigs' Syndrome

Background: The clinical triad presentation of a benign ovarian tumor (fibroma, thecoma, granulosa-cell tumor), ascites, and hydrothorax that resolve after removal of the aforementioned tumor chara...

Carcinoma-Associated Mesenchymal Stem Cells Promote Chemoresistance in Ovarian Cancer Stem Cells via PDGF Signaling.

Within the ovarian cancer tumor microenvironment, cancer stem-like cells (CSC) interact with carcinoma associated mesenchymal stem/stromal cells (CA-MSC) through multiple secreted cytokines and growth factors. These paracrine interactions have been revealed to cause enrichment of CSC and their chemoprotection; however, it is still not known if platelet-derived growth factor (PDGF) signaling is involved in facilitating these responses. In order to probe this undiscovered bidirectional communication, we created a model of ovarian malignant ascites in the three-dimensional (3D) hanging drop heterospheroid array, with CSC and CA-MSC. We hypothesized that PDGF secretion by CA-MSC increases self-renewal, migration, epithelial to mesenchymal transition (EMT) and chemoresistance in ovarian CSC. Our results indicate that PDGF signaling in the CSC-MSC heterospheroids significantly increased stemness, metastatic potential and chemoresistance of CSC. Knockdown of PDGFB in MSC resulted in abrogation of these phenotypes in the heterospheroids. Our studies also reveal a cross-talk between PDGF and Hedgehog signaling in ovarian cancer. Overall, our data suggest that when the stromal signaling via PDGF to ovarian CSC is blocked in addition to chemotherapy pressure, the tumor cells are significantly more sensitive to chemotherapy. Our results emphasize the importance of disrupting the signals from the microenvironment to the tumor cells, in order to improve response rates. These findings may lead to the development of combination therapies targeting stromal signaling (such as PDGF and Hedgehog) that can abrogate the tumorigenic, metastatic and platinum resistant phenotypes of ovarian CSC through additional investigations.

Abstract B03: Immunotherapy of ovarian cancer with glycomimetic peptides

Abstract Successful strategies for treating women with ovarian cancer remain elusive. Whereas chemotherapy with drugs such as paclitaxel and carboplatin extends survival, it bears a significant cost in toxicity. Immunotherapies with antibodies such as anti-PD-1, anti-PD-L1, or anti-VEGF have been successful in a fraction of patients. Inhibitors of poly(ADP-ribose) polymerase (PARP) have gained interest, particularly for the minority of patients who carry the BRCA-1/2 mutations. Ovarian cancer is highly inflammatory and recent reports described recruitment of monocytes, which then differentiate into a unique subset of dendritic cells (DCs) within the inflamed ascites environment. These monocyte-derived DCs (mo-DCs) have the potential to activate cytotoxic CD8+ T cells that attack tumor cells, but progression of disease is not abrogated without additional stimuli. We hypothesize that a means to actuate this role of mo-DCs will be an important component of a successful treatment of inflammatory tumors such as ovarian ascites. Mo-DCs along with CD1c+ DC2 subtypes express CD301, the Ca2+-dependent lectin domain family 10 member A (CLEC10A), which is a pathogen-recognition receptor specific for binding the ligand N-acetylgalactoasmine (GalNAc). A series of experiments were designed to test whether a novel peptide mimetic of GalNAc, designated sv6D, can enhance anticancer immune activity and limit the progression of ovarian cancer. CLEC10A is a type II transmembrane receptor that initiates a Ca2+ signal upon binding of sv6D and subsequent endocytosis. Production of IFN-γ by naïve T cells occurred when cultured with in vitro generated mo-DCs, which are similar to mo-DCs induced by inflammation, and 10 nM sv6D. In a syngeneic, orthotopic murine model of ovarian cancer, doses of 0.1 nmole/g of sv6D on alternate days completely suppressed ascites accumulation for several weeks, a measure of inhibition of tumor progression. Survival was also extended when sv6D was administered to mice previously treated with paclitaxel. Although treatment with anti-PD-1 was ineffective, i.p. injections of anti-PD-1 in combination with a tolerance-inducing treatment with sv6D provided maximal survival. Our studies demonstrate that 1) sv6D stimulates proliferation and differentiation of immune cells in the peritoneal cavity and serves as a trigger to promote the activation of CD8+ T cells by mo-DCs in ovarian ascites, 2) sv6D as a single agent inhibits progression of ovarian cancer and enhances survival in a mouse model of ovarian cancer, 3) sv6D in combination with paclitaxel or anti-PD-1 extends survival beyond that of either agent alone, and 4) sv6D is not antigenic and treatment with the peptide was not associated with evident toxicity. Taken together, these data demonstrate the potential for this novel approach of harnessing lectin receptors as a means toward an effective ovarian cancer treatment. Citation Format: Laura L. Eggink, J. Kenneth Hoober. Immunotherapy of ovarian cancer with glycomimetic peptides [abstract]. In: Proceedings of the AACR Special Conference on Advances in Ovarian Cancer Research; 2019 Sep 13-16, 2019; Atlanta, GA. Philadelphia (PA): AACR; Clin Cancer Res 2020;26(13_Suppl):Abstract nr B03.

The strategic combination of trastuzumab emtansine with oncolytic rhabdoviruses leads to therapeutic synergy

We have demonstrated that microtubule destabilizing agents (MDAs) can sensitize tumors to oncolytic vesicular stomatitis virus (VSVΔ51) in various preclinical models of cancer. The clinically approved T-DM1 (Kadcyla®) is an antibody-drug conjugate consisting of HER2-targeting trastuzumab linked to the potent MDA and maytansine derivative DM1. We reveal that combining T-DM1 with VSVΔ51 leads to increased viral spread and tumor killing in trastuzumab-binding, VSVΔ51-resistant cancer cells. In vivo, co-treatment of VSVΔ51 and T-DM1 increased overall survival in HER2-overexpressing, but trastuzumab-refractory, JIMT1 human breast cancer xenografts compared to monotherapies. Furthermore, viral spread in cultured HER2+ human ovarian cancer patient-derived ascites samples was enhanced by the combination of VSVΔ51 and T-DM1. Our data using the clinically approved Kadcyla® in combination with VSVΔ51 demonstrates proof of concept that targeted delivery of a viral-sensitizing molecule using an antibody-drug conjugate can enhance oncolytic virus activity and provides rationale for translation of this approach.

Abstract TMIM-063: TARGETING NEUROPILIN-1+ T REGULATORY CELLS IN PATIENTS WITH HIGH GRADE SEROUS OVARIAN CANCER DECREASES TREG-SPECIFIC SUPPRESSION OF CD8+ T CELLS

Abstract Regulatory T cells (Treg) are a subpopulation of CD4+ T cells that suppress autoimmune responses, but also prevent clearance of tumors and chronic viral infections. In high grades serous ovarian cancer, a higher frequency of tumor infiltrating (TIL) Treg are associated with poor prognosis, but mechanisms governing the suppressive activity of TIL Treg in this context are limited. Our group has recently described a signaling axis through neuropilin-1 (NRP1) on TIL Treg in murine models of cancer that promotes the survival and suppressive function of Treg. When NRP1 is specifically knocked out on murine TIL Treg, there is reduced tumor growth and increased survival similar to the complete knockout of TIL Tregs, however, without death from overt autoimmunity. Thus, NRP1 is a viable target to specifically reduce TIL Treg suppressive function in the tumor microenvironment (TME), ultimately leading to increased anti-tumor immunity without adverse events. Given the importance of NRP1+ TIL Treg in murine cancer models, we sought to understand the role of NRP1 on TIL Treg from patients with high grade serious ovarian cancer. Surface and total NRP1 expression was assessed by flow cytometry on CD4+CD25+CD127loFOXP3+ Treg from healthy donor PBL and ovarian cancer TIL or ascites fluid. Total NRP1 was expressed on a median of 1.8% (interquartile range [IQR]: 0.69% to 4.8%) of Treg from healthy donors compared with a median of 66% (IQR: 28% to 90%; p<0.001) and 82% (IQR: 38% to 99%; p=0.004) of Treg from ovarian TIL and ascites, respectively. Surface NRP1 was detected on 0.1% (IQR: 0% to 1%) of Treg in PBL from healthy donors, compared with 11.1% (IQR: 1.1% to 60%; p=0.01) on ovarian TIL and 82% (IQR: 14% to 82%; p=0.0015) on ascites. Further, in comparing expression of NRP1 on Treg from benign ovarian disease and malignant ovarian tumors, there was a trend toward increased NRP1 expression on Tregs from malignant disease (median 9.3% versus 54.5%, respectively; p=0.044). Finally, NRP1+ TIL Treg isolated from primary tumors or ascites fluid were capable of suppressing CD8+ T cell proliferation in a dose-dependent manner and suppression was abrogated by addition of an anti-NRP1 antibody. In summary, both surface and total NRP1 are expressed more frequently on Treg from TIL and ascites fluid compared to Treg from healthy donor PBL and NRP1+ Tregs in the TME are more suppressive compared to NRP1- Tregs. NRP1 is a viable target to reduce Treg suppressive function in ovarian cancer tumors, which can be immunologically ““cold””. This could ultimately lead to increased CD8+ T cell infiltration and function in these patient tumors, which could then increase responsiveness to anti-PD1 as it relies upon CD8 T cell infiltration to be effective. Citation Format: Anthony R. Cillo, Christopher A. Chuckran, Mengting Liao, Francesmary Modugno, Robert Edwards, Lan Coffman, Dario A.A. Vignali, Tullia C. Bruno. TARGETING NEUROPILIN-1+ T REGULATORY CELLS IN PATIENTS WITH HIGH GRADE SEROUS OVARIAN CANCER DECREASES TREG-SPECIFIC SUPPRESSION OF CD8+ T CELLS [abstract]. In: Proceedings of the 12th Biennial Ovarian Cancer Research Symposium; Sep 13-15, 2018; Seattle, WA. Philadelphia (PA): AACR; Clin Cancer Res 2019;25(22 Suppl):Abstract nr TMIM-063.

Abstract LB-022: Targeting glutamine metabolism as a mean of treating a murine model of ovarian cancer and ascites development

Abstract Malignant ascites in ovarian cancer develops in the setting of recurrent and advanced metastatic disease and is associated with poor prognosis. Emerging evidence has demonstrated that ovarian cancer patients have altered metabolism and an immunosuppressive environment in the ascites fluid. Inasmuch as the rapid proliferation of ovarian cancer cells and development of ascites is dependent on glutamine metabolism, we hypothesized that targeting the glutamine metabolism can inhibit the development of ascites and enhance anti-tumor immunity in ovarian cancer. To test this hypothesis, we developed a novel small molecule glutamine antagonist (prodrug of 6-Diazo-5-oxo-l-norleucine, JHU-083). By employing JHU-083, we evaluated this hypothesis in mice bearing an aggressive and metastatic ovarian cancer (ID8 cell line with an overexpression of Defb29 and Vegfa). Targeting glutamine metabolism led to markedly reduced progression of ascites along with reduced tumor cell numbers. Furthermore, JHU-083 treatment also led to a marked diminution of the volume of fluid in mice with already established ascites. Inhibition of glutamine metabolism also led to a less suppressive tumor microenvironment by blocking the recruitment of myeloid derived suppressor cells (MDSCs) and tumor-associated macrophages (TAMs) to the ascites fluid. Functionally, both the TAMs and tumor cells from the JHU-083 treated group showed a lower expression of PDL1 compared to the vehicle treated group. Additionally, we also observed reduced regulatory T cell (T regs) percentages and numbers with JHU-083 treatment. These findings are consistent with our previous observations that targeting glutamine metabolism can inhibit the generation and recruitment of MDSC and T regs by targeting both tumor cell and immune cell metabolism. Further, LC-MS based metabolite analysis of the ovarian cancer ascites fluid from JHU-083 treated mice revealed distinct differences in urea-ornithine pathway, nucleotide synthesis, and redox balance related metabolites. In light of these findings, ongoing experiments are examining the efficacy of JHU-083 in combination with epigenetic drugs, VEGF inhibitors, PARP inhibitors, and checkpoint blockade. These studies suggest that targeting glutamine metabolism may represent a novel approach to treating metastatic ovarian cancer and ascites. Citation Format: Min-Hee Oh, Meghan Travers, Stephen Brown, Liang Zhao, Im-Meng Sun, Im-Hong Sun, Matthew Arwood, Wei Xu, Samuel Collins, Robert Leone, Eva Prchalova, Rana Rais, Barbara Slusher, Maureen Horton, Cynthia Zahnow, Jonathan Powell. Targeting glutamine metabolism as a mean of treating a murine model of ovarian cancer and ascites development [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr LB-022.

An omentum-inspired 3D PEG hydrogel for identifying ECM-drivers of drug resistant ovarian cancer.

Ovarian cancer (OvCa) is a challenging disease to treat due to poor screening techniques and late diagnosis. There is an urgent need for additional therapy options, as patients recur in 70% of cases. The limited availability of clinical treatment options could be a result of poor predictions in early stage drug screens on standard tissue culture polystyrene (TCPS). TCPS does not capture the mechanical and biochemical cues that cells experience in vivo, which can impact how cells will respond to a drug. Therefore, an in vitro model that captures some of the microenvironment features that the cells experience in vivo could provide better insights into drug responses. In this study, we formed 3D multicellular tumor spheroids (MCTS) in microwells and encapsulated them in 3D omentum-inspired hydrogels. SKOV-3 MCTS were resistant to Paclitaxel in our 3D hydrogels compared to a monolayer on TCPS. Toward clinical application, we tested cells from patients [ovarian carcinoma ascites spheroids (OCAS)] who had been treated with Paclitaxel, and drug responses predicted by using the 3D omentum-inspired hydrogels demonstrated the lack of the Paclitaxel response of these samples. Additionally, we observed the presence of collagen production around the encapsulated SKOV-3 MCTS, but not significantly on TCPS. Our results demonstrated that our 3D omentum-inspired hydrogel is an improved in vitro drug testing platform to study the OvCa drug response for patient-derived cells and helped us identify collagen 3 as a potential driver of Paclitaxel resistance in 3D.

Nanoformulation of Talazoparib Delays Tumor Progression and Ascites Formation in a Late Stage Cancer Model.

Talazoparib, a potent PARP inhibitor, induces synthetic lethality in BRCA-deficient cancers making it an attractive candidate for ovarian cancer treatment. However, its potency lends itself to side effects associated more closely with traditional chemotherapeutics than other clinically approved PARP inhbitors. We sought to formulate Talazoparib in a nanoparticle delivery system, which allows the drug to be administered intraperitoneally. This was done to specifically target peritoneal dissemination of late stage metastatic ovarian cancer and increase talazoparib's therapeutic efficacy while minimizing toxic side effects. NanoTalazoparib was developed and characterized with regard to its size, loading, and surface charge. Talazoparib and NanoTalazoparib were tested on a panel of murine and human BRCA cell lines and the dose response was compared to Olaparib's, the currently used PARP inhibitor. Therapeutic efficacy was tested in vivo in a Brca peritoneal cancer model that mimics late stage disseminated disease. NanoTalazoparib has a diameter of about 70 nm with a neutral surface charge and ~75% encapsulation efficiency, which slowly releases the drug over several hours. Dose response analysis indicated that the murine cell lines with conditional BRCA1/2, PTEN, and TP53 deletions had the lowest IC50s. NanoTalazoparib administered on a schedule of three doses weekly slowed disease progression and resulted in significantly less mice with ascites at the end point compared to controls. These results indicate that the slow release nanoformulation, NanoTalazoparib, effectively delivers PARP inhibitor therapy to the peritoneal cavity for disseminated cancer treatment. The ability to decrease ascites formation with the introduction of intraperitoneal NanoTalazoparib suggests this treatment may be an effective way to treat ovarian cancer-associated ascites and slow disease progression.

A Case of Ovarian Carcinoid Heart Disease

We presented a 68-year-old lady who had total abdominal hysterectomy and bilateral salpingo-oophorectomy performed for a 7 cm complex ovarian tumor and ascites on ultrasound scan. Histopathology report confirmed the diagnosis of ovarian carcinoid tumor. This lady presented with gross ascites post-operatively, echocardiogram revealed right heart overload, tricuspid and pulmonary valve regurgitation compatible with carcinoid heart disease. Tricuspid and pulmonary heart replacement was performed for this lady and she had an uneventful recovery. J Clin Gynecol Obstet. 2019;8(1):29-31 doi: https://doi.org/10.14740/jcgo539

PRSS21/testisin inhibits ovarian tumor metastasis and antagonizes proangiogenic angiopoietins ANG2 and ANGPTL4.

Ovarian cancer is the leading cause of death among all the gynecological cancers in the USA. Ovarian cancer employs a unique mode of metastasis, as exfoliated tumor cells disseminate within the peritoneal cavity, colonizing in several sites as well as accumulating ascites. Tumor recurrence and widespread metastasis are significant factors contributing to poor prognosis. PRSS21 is a metastasis-associated ovarian cancer gene that encodes the glycosyl-phosphatidylinositol-linked serine protease, testisin. Testisin expression is increased in multiple ovarian tumor types, with relatively little expression in normal tissues, but is differentially decreased in metastatic ovarian serous carcinomas compared to primary tumors. Here we explored the function of testisin in late-stage ovarian cancer progression using a murine xenograft model of ovarian intraperitoneal tumor metastasis. Increased tumor testisin expression inhibited intra-peritoneal tumor seeding and colonization, ascites accumulation, and metastatic tumor burden that was dependent on catalytically active testisin. The known testisin substrate, protease-activated receptor-2 (PAR-2), is a target of testisin activity. Gene profiling and mechanistic studies demonstrate that testisin activity suppresses the synthesis and secretion of pro-angiogenic angiopoietins, ANG2 and ANGPTL4, which normally promote vascular leak and edema. These observations support a model wherein testisin activates PAR-2 to antagonize proangiogenic angiopoietins that modulate vascular permeability and ascites accumulation associated with ovarian tumor metastasis. KEY MESSAGES: Testisin inhibits metastatic ovarian tumor burden and ascites production. Testisin activity antagonizes ANG2 and ANGPTL4 synthesis and secretion. PAR-2 is a proteolytic target of testisin on the surface of ovarian cancer cells.

ПАРАМЕТРЫ ЭРИТРОПОЭЗА И ЦИТОАРХИТЕКТОНИКА ЦИРКУЛИРУЮЩИХ ЭРИТРОЦИТОВ КРЫС С АСЦИТНОЙ ОПУХОЛЬЮ ЯИЧНИКОВ

Developing neoplasm can affect the erythropoiesis of the tumor-bearer. It is found out that the degree and nature of such effect depend on tumor biological characteristics. The purpose of the study is to examine erythrocyte morphometric parameters and erythropoiesis change in tumor-bearing animals under neoplastic process development. Materials and Methods. Peripheral blood of experimental animals was used as trial material. Blood sampling was carried out during stationary (n=64) and terminal (n=64) tumor growth phases. Healthy adult rats (n=62) composed the control group. To assess erythropoiesis, the authors determined erythrocyte content, hemoglobin level, reticulocyte count, and erythropoietin concentration in the peripheral blood of tumor-bearing animals. Cytoarchitectonics was studied using atomic force microscopy. Results. Significant reduction in the number of red blood cells and decrease in hemoglobin level was established. The erythropoietin level in blood plasma increased during the stationary phase as well as the number of reticulocytes in blood during all periods of tumor growth. Erythrocyte cytoarchitectonics changed: echinocytes prevailed in the stationary phase (52%), spherocytes – in the terminal phase (50.8 %). Conclusion. The data obtained suggest that, on the background of intense erythropoiesis, the number of erythrocytes in peripheral blood falls, the hemoglobin level decreases, there is some change in cytoarchitectonics, which may indicate a toxic effect of the tumor on the hematopoietic system. Keywords: erythrocytes, erythropoietin, ovarian ascites tumor.

Abstract A056: Incessant ER stress responses promote dendritic cell dysfunction in ovarian cancer

Abstract Harnessing the intrinsic ability of our immune system to recognize and eliminate malignanT-cells represents the most promising anticancer strategy since the development of chemotherapy. However, hostile microenvironmental conditions within aggressive solid tumors inhibit the optimal activity of protective immune cells. Targeting immunosuppression and re-programming immune cell function in the tumor microenvironment are thus fundamental requirements for developing successful cancer immunotherapies. Our CRI postdoctoral project aims at identifying, understanding and disabling the molecular mechanisms by which endoplasmic reticulum (ER) stress responses inhibit the natural function of dendritic cells (DCs) in the ovarian cancer microenvironment. The central hypothesis of this study is that ovarian tumors trigger ER stress and aberrant activation of the IRE1-XBP1 pathway in infiltrating DCs to cripple key immuno-metabolic processes and impede the development of protective T-cell responses. To determine how IRE1α-XBP1 overactivation defines regulatory DC phenotypes in the ovarian cancer microenvironment, metastatic ovarian tumors were developed in ER stress-Activated Indicator (ERAI) reporter mice. We found that DCs demonstrating IRE1 activation in the tumor microenvironment overexpress tolerogenic and immunosuppressive molecules. Next, to determine whether tumor-derived factors may affect DC metabolism, we optimized an ex vivo culture system that recreates the tumor microenvironment using malignant ascites samples from ovarian cancer patients. We treated human monocyte-derived DCs from healthy donors with patient-derived ovarian cancer malignant ascites supernatants and assessed the bioenergetic profile of DCs. Oxygen consumption rate (OCR), which measures mitochondrial respiration, ATP production and spare respiratory capacity, was increased in DCs exposed to ascites supernatants. We found that these metabolic changes upon ascites treatment relied on IRE1a-XBP1 pathway. Further, since therapeutic DC-based vaccines have shown limited effects in ovarian cancer patients, we tested the novel translational hypothesis that XBP1-deficient bone marrow-derived DCs (BMDCs) would be better equipped to endure and function in the tumor microenvironment when used as therapeutic vaccines. While adoptive transfer of WT BMDCs did not induce any therapeutic effect, treatment with XBP1-deficient BMDCs elicited a marked increase in overall host survival. This result suggest that compared with WT BMDCs, their XBP1-deficient counterparts were resistant to the immunosuppressive effects of the tumor microenvironment. Our results provide a unique mechanistic rationale for targeting the IRE1-XBP1 arm of the ER stress response as a potent approach to reprogram and enhance antitumor immune cell function in cancer. These findings should also pave the way for devising a new generation of cancer immunotherapies that may improve the dismal survival of >21,000 American women affected by ovarian cancer each year. Citation Format: Chang-Suk Chae. Incessant ER stress responses promote dendritic cell dysfunction in ovarian cancer [abstract]. In: Proceedings of the Fourth CRI-CIMT-EATI-AACR International Cancer Immunotherapy Conference: Translating Science into Survival; Sept 30-Oct 3, 2018; New York, NY. Philadelphia (PA): AACR; Cancer Immunol Res 2019;7(2 Suppl):Abstract nr A056.

Suppression of chemotherapy-induced cytokine/lipid mediator surge and ovarian cancer by a dual COX-2/sEH inhibitor

Although chemotherapy is a conventional cancer treatment, it may induce a protumorigenic microenvironment by triggering the release of proinflammatory mediators. In this study, we demonstrate that ovarian tumor cell debris generated by first-line platinum- and taxane-based chemotherapy accelerates tumor progression by stimulating a macrophage-derived "surge" of proinflammatory cytokines and bioactive lipids. Thus, targeting a single inflammatory mediator or pathway is unlikely to prevent therapy-induced tumor progression. Here, we show that combined pharmacological abrogation of the cyclooxygenase-2 (COX-2) and soluble epoxide hydrolase (sEH) pathways prevented the debris-induced surge of both cytokines and lipid mediators by macrophages. In animal models, the dual COX-2/sEH inhibitor PTUPB delayed the onset of debris-stimulated ovarian tumor growth and ascites leading to sustained survival over 120 days postinjection. Therefore, dual inhibition of COX-2/sEH may be an approach to suppress debris-stimulated ovarian tumor growth by preventing the therapy-induced surge of cytokines and lipid mediators.

Sialic Acid-Dependent Inhibition of T Cells by Exosomal Ganglioside GD3 in Ovarian Tumor Microenvironments.

The tumor microenvironment is rendered immunosuppressive by a variety of cellular and acellular factors that represent potential cancer therapeutic targets. Although exosomes isolated from ovarian tumor ascites fluids have been previously reported to induce a rapid and reversible T cell arrest, the factors present on or within exosomes that contribute to immunosuppression have not been fully defined. In this study, we establish that GD3, a ganglioside expressed on the surface of exosomes isolated from human ovarian tumor ascites fluids, is causally linked to the functional arrest of T cells activated through their TCR. This arrest is inhibited by Ab blockade of exosomal GD3 or by the removal of GD3+ exosomes. Empty liposomes expressing GD3 on the surface also inhibit the activation of T cells, establishing that GD3 contributes to the functional arrest of T cells independent of factors present in exosomes. Finally, we demonstrate that the GD3-mediated arrest of the TCR activation is dependent upon sialic acid groups, because their enzymatic removal from exosomes or liposomes results in a loss of inhibitory capacity. Collectively, these data define GD3 as a potential immunotherapeutic target.