Immunotherapy Of Ovarian Cancer Research Articles

Immunotherapy in Ovarian Cancer: Are We There Yet?

Immunotherapy in Ovarian Cancer: Are We There Yet?

Naturally Killing the Silent Killer: NK Cell-Based Immunotherapy for Ovarian Cancer.

Ovarian cancer (OC) is diagnosed in ~22,000 women in the US each year and kills 14,000 of them. Often, patients are not diagnosed until the later stages of disease, when treatment options are limited, highlighting the urgent need for new and improved therapies for precise cancer control. An individual's immune function and interaction with tumor cells can be prognostic of the response to cancer treatment. Current emerging therapies for OC include immunotherapies, which use antibodies or drive T cell-mediated cancer recognition and elimination. In OC, these have been limited by adverse side effects and tumor characteristics including inter- and intra-tumoral heterogeneity, lack of targetable antigens, loss of tumor human leukocyte antigen expression, high levels of immunosuppressive factors, and insufficient immune cell trafficking. Natural killer (NK) cells may be ideal as primary or collateral effectors to these nascent immunotherapies. NK cells exhibit multiple functions that combat immune escape and tumor relapse: they kill targets and elicit inflammation through antigen-independent pathways and detect loss of HLA as a signal for activation. NK cells are efficient mediators of tumor immune surveillance and control, suppressed by the tumor microenvironment and rescued by immune checkpoint blockade. NK cells are regulated by a variety of activating and inhibitory receptors and already known to be central effectors across an array of existing therapies. In this article, we highlight interactions between NK cells and OC and their potential to change the immunosuppressive tumor microenvironment and participate in durable immune control of OC.

Combined Strategies with Poly (ADP-Ribose) Polymerase (PARP) Inhibitors for the Treatment of Ovarian Cancer: A Literature Review.

Poly (ADP-ribose) polymerase (PARP) inhibitors are the first clinically approved drugs designed to exploit synthetic lethality, and were first introduced as a cancer-targeting strategy in 2005. They have led to a major change in the treatment of advanced ovarian cancer, and altered the natural history of a disease with extreme genetic complexity and defective DNA repair via homologous recombination (HR) pathway. Furthermore, additional mechanisms apart from breast related cancer antigens 1 and 2 (BRCA1/2) mutations can also result in HR pathway alterations and consequently lead to a clinical benefit from PARP inhibitors. Novel combinations of PARP inhibitors with other anticancer therapies are challenging, and better understanding of PARP biology, DNA repair mechanisms, and PARP inhibitor mechanisms of action is crucial. It seems that PARP inhibitor and biologic agent combinations appear well tolerated and clinically effective in both BRCA-mutated and wild-type cancers. They target differing aberrant and exploitable pathways in ovarian cancer, and may induce greater DNA damage and HR deficiency. The input of immunotherapy in ovarian cancer is based on the observation that immunosuppressive microenvironments can affect tumour growth, metastasis, and even treatment resistance. Several biologic agents have been studied in combination with PARP inhibitors, including inhibitors of vascular endothelial growth factor (VEGF; bevacizumab, cediranib), and PD-1 or PD-L1 (durvalumab, pembrolizumab, nivolumab), anti-CTLA4 monoclonal antibodies (tremelimumab), mTOR-(vistusertib), AKT-(capivasertib), and PI3K inhibitors (buparlisib, alpelisib), as well as MEK 1/2, and WEE1 inhibitors (selumetinib and adavosertib, respectively). Olaparib and veliparib have also been combined with chemotherapy with the rationale of disrupting base excision repair via PARP inhibition. Olaparib has been investigated with carboplatin and paclitaxel, whereas veliparib has been tested additionally in combination with temozolomide vs. pegylated liposomal doxorubicin, as well as with oral cyclophosphamide, and topoisomerase inhibitors. However, overlapping myelosuppression observed with PARP inhibitor and chemotherapy combinations requires further investigation with dose escalation studies. In this review, we discuss multiple clinical trials that are underway examining the antitumor activity of such combination strategies.

Abstract 3208: Using T cell engineering plus triple checkpoint blockade to enhance the efficacy of adoptive immunotherapy in ovarian cancer

Abstract Over 20,000 women are diagnosed with ovarian cancer in the United States annually, and over half will die within 5 years. Outcomes have changed little in the last 20 years, highlighting the need for therapy innovation. One promising new strategy employs immune T cells engineered to target proteins uniquely overexpressed in tumors; such T cell immunotherapies have the potential to control tumor growth without toxicity to healthy tissues. In considering candidate immunotherapy targets, we focused on mesothelin (MSLN), which contributes to invasive progression and malignancy in ovarian cancer but has limited expression in healthy cells. We showed that T cells engineered to express a human or mouse MSLN-specific high-affinity T cell receptor (TCRMSLN) can kill human patient-derived ovarian cancer cell lines or the murine ID8 cell line, respectively. In a disseminated ID8 tumor model, adoptively transferred TCRMSLN T cells preferentially accumulated within established tumors, delayed ovarian tumor growth, and significantly prolonged mouse survival. However, our data also revealed that the ovarian tumor microenvironment (TME) limits engineered T cell persistence and cancer cell killing. To identify immunosuppressive features active in both the human and murine ovarian TME, we performed gene expression analyses. Deep transcriptome profiling confirmed similar gene expression signatures in human cancers and in the preclinical ID8 model. Among these, RNA sequencing detected PD-L1, Galectin-9 and Galectin-3, ligands for CD8 T cell-expressed PD-1, Tim-3 and Lag-3 ‘checkpoint’ receptors, respectively. We also measured PD-L1, Galectin-9 and Galectin-3 expression in human and mouse ovarian cancers by flow cytometry and immunohistochemistry, and multiplex immunohistochemistry of human ovarian tumors confirmed the presence of endogenous CD8 T cells expressing one, two or all three inhibitory receptors. Moreover, flow cytometry revealed that TCRMSLN-transduced T cells increase expression of the inhibitory receptors in ID8 tumors relative to cells in the spleen as early as three weeks after transfer, in association with decreased production of anti-tumor cytokines. Based on our results, we hypothesized that we could overcome engineered T cell suppression via inhibitory receptor ligation. We treated tumor-bearing mice with TCRMSLN T cells plus anti-PD-1, anti-Tim-3 and/or anti-Lag-3 checkpoint-blocking antibodies, targeting up to three inhibitory receptors simultaneously. Triple checkpoint blockade dramatically increased anti-tumor cytokine production by intratumoral TCRMSLN T cells. As many solid tumors both overexpress MSLN as well as PD-1, Tim-3 and Lag-3, the use of multi-checkpoint blockade with engineered T cells has real potential to also enhance the efficacy of engineered adoptive T cell therapy against other malignancies. Citation Format: Kristin G. Anderson, Madison G. Burnett, Valentin Voillet, Edison Y. Chiu, Breanna M. Bates, Nicolas M. Garcia, Raphael Gottado, Philip D. Greenberg. Using T cell engineering plus triple checkpoint blockade to enhance the efficacy of adoptive immunotherapy in ovarian cancer [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 3208.

Ovarian Cancer Immunotherapy: Turning up the Heat.

Epithelial ovarian cancer (EOC) is the leading cause of death among gynecological malignancies. Despite surgery and chemotherapy, 5-years survival rates have improved only modestly over the past few decades remaining at 45% for advanced stages. Therefore, novel therapies are urgently needed. The presence of tumor-infiltrating lymphocytes (TILs) in OC tumor microenvironment (TME) has already proved to be correlated with overall survival (OS), while immune evasion mechanisms are associated with poor prognosis. Although these data indicate that immunotherapy has a strong rationale in OC, single agent immune-checkpoints inhibitors (ICIs) have shown only modest results in this malignancy. In this review, we will discuss immune-targeting combination therapies and adoptive cell therapy (ACT), highlighting the challenges represented by these strategies, which aim at disrupting the stroma-tumor barrier to boost immune system against ovarian cancer.

Subsequent therapies and survival after immunotherapy in recurrent ovarian cancer

Subsequent therapies and survival after immunotherapy in recurrent ovarian cancer

Hypermetabolic activity by FDG-PET after immunogenic chemotherapy and multi-peptide immunotherapy in ovarian cancer.

e17079 Background: There are several reports of increased of SUV in the lymph nodes of cancer patients after immune manipulation such as the administration of vaccines and checkpoint inhibitors. However the clinical importance of these phenomena is poorly understood. The administration of two immunogenic drugs and eight peptides in HGSOC induced atypical bright zones in multiple lymph nodes and, in areas with microscopic disease where potentially we can have cancer stem cells (CSC’s). Methods: We enrolled N = 10 HGSOC after the local IRB ethic committee approval. All the patients had 3 recurrences with mPFS = 8 months of the third relapse. The last FDG-PET scan was used as basal image for the study. Blood was collected for cellular and humoral immunology analysis such as Granzyme B ELISPOT and ELISA. Tissue was used for IHC analysis for the evaluation of CD8, FOXP3, Th1, and proteins related with CSC’s. The patients received 50 mg of oxaliplatin and 30 mg of doxorubicin total dose every week four times simultaneously with multi peptide immunotherapy. A second FDG-PET scan was performed after the termination of the treatment. Results: After the treatment 100% of the patients showed intense atypical bright uptake areas in lymph nodes and in the peritoneum. There was a correlation between the brightness intensity (SUV), and the Granzyme B production (p = 0.001). We found multiple bright small lesions in the peritoneum that were not visible before treatment. We demonstrated the presence of proteins related with CSC’s in the original tumor tissue and an antibody immune response against EGFR (P = 0.005), Ape-1 (p = 0.003) and Bcl-2 (p = 0.05). Conclusions: Immunotherapy may produce hypermetabolic activity that could lead to overtreatment when evaluated by FDG-PET in HGSOC. Vaccination may activate lymph nodes and anti-cancer immune interventions may also activate CD8 and Th1 cells able to accumulate in CSC’s clusters and increased notably the SUV, which may lead to false relapse interpretation by the radiologists and oncologists.

Synergistic activity between IL-15 signaling and checkpoint blockade drives enhanced NK cell expansion and tumor control in ovarian cancer

Abstract Survival in ovarian cancer patients has not improved in the past 40 years, stressing a need for new lines of therapy. NK cell immunotherapy in ovarian cancer has not been extensively explored due to limited data showing defective NK cell function in these patients. Our previous work shows that an IL-15 super-agonist (NANT N-803 (formerly ALT-803)) can bypass some of the deficiencies. However, we show here that though N-803 enhances NK cell activation, it also induces NK PD-1 expression and inflammatory cytokines secreted by the NK cells induce PD-L1 expression on ovarian tumors. To bypass this negative feedback we combined N-803 with an anti-PD-L1 antibody (Avelumab) and show a potent increase in NK cell activation and long-term real-time in vitro tumor killing. Furthermore, combined N-803/Avelumab induces robust killing of ovarian cancer tumor spheroids, not seen with individual treatments. To evaluate the benefits of this combined treatment in vivo we tested them in a xenogeneic model of ovarian cancer containing human ovarian cancer cells (MA148lucs or OVCAR8lucs) and human NK cells. Our data clearly shows reduced tumor burden, by bioluminescent imaging, and potently increased NK cell expansion with the combined treatment when compared to individual treatments. Since Avelumab is capable of driving antibody dependent cell-mediated cytotoxicity (ADCC) we wanted to evaluate the impact of checkpoint signals in the synergy excluding ADCC using an anti-PD-1 antibody (Pembrolizumab). Combination of N-803 with Pembrolizumab yielded similar tumor control and NK cell expansion in the in vivo model, indicating that the synergy lies in checkpoint signals and IL-15 signaling, and not just in amplification of ADCC via N-803.

Combining Vascular Normalization with an Oncolytic Virus Enhances Immunotherapy in a Preclinical Model of Advanced-Stage Ovarian Cancer.

Intravenous delivery of oncolytic viruses often leads to tumor vascular shutdown, resulting in decreased tumor perfusion and elevated tumor hypoxia. We hypothesized that using 3TSR to normalize tumor vasculature prior to administration of an oncolytic Newcastle disease virus (NDV) would enhance virus delivery and trafficking of immunologic cell subsets to the tumor core, resulting in systemically enhanced immunotherapy and regression of advanced-stage epithelial ovarian cancer (EOC). Using an orthotopic, syngeneic mouse model of advanced-stage EOC, we pretreated mice with 3TSR (4 mg/kg per day) alone or followed by combination with fusogenic NDV(F3aa) (1.0 × 108 plaque-forming units). Treatment with 3TSR normalized tumor vasculature, enhanced blood perfusion of primary EOC tumors, and induced disease regression. Animals treated with combination therapy had the greatest reduction in primary tumor mass, ascites accumulation, and secondary lesions (50% of mice were completely devoid of peritoneal metastases). Combining 3TSR + NDV(F3aa) led to enhanced trafficking of immunologic cells into the primary tumor core. We have shown, for the first time, that NDV, like other oncolytic viruses, is a potent mediator of acute vascular shutdown and that preventing this through vascular normalization can promote regression in a preclinical model of advanced-stage ovarian cancer. This challenges the current focus on induction of intravascular thrombosis as a requisite for successful oncolytic virotherapy.See related commentary by Bykov and Zamarin, p. 1446.

Nanotechnology and Immunotherapy in Ovarian Cancer: Tracing New Landscapes.

Ovarian cancer (OC) is the seventh most common cancer in women worldwide. Standard therapeutic treatments involve debulking surgery combined with platinum-based chemotherapies. Of the patients with advanced-stage cancer who initially respond to current treatments, 50%-75% relapse. Immunotherapy-based approaches aimed at boosting antitumor immunity have recently emerged as promising tools to challenge tumor progression. Treatments with inhibitors of immune checkpoint molecules have shown impressive results in other types of tumors. However, only 15% of checkpoint inhibitors evaluated have proven successful in OC due to the immunosuppressive environment of the tumor and the transport barriers. This limits the efficacy of the existing immunotherapies. Nanotechnology-based delivery systems hold the potential to overcome such limitations. Various nanoformulations including polymeric, liposomes, and lipid-polymer hybrid nanoparticles have already been proposed to improve the biodistribution and targeting capabilities of drugs against tumor-associated immune cells, including dendritic cells and macrophages. In this review, we examine the impact of immunotherapeutic approaches that are currently under consideration for the treatment of OC. In this review, we also provide a comprehensive analysis of the existing nanoparticle-based synthetic strategies and their limitations and advantages over standard treatments. Furthermore, we discuss how the strength of the combination of nanotechnology with immunotherapy may help to overcome the current therapeutic limitations associated with their individual application and unravel a new paradigm in the treatment of this malignancy.

Immunotherapy in ovarian cancer: fake news or the real deal?

Cancer immunotherapy has emerged as one of the most promising approaches in oncology, and comprises the activation of the immune system to induce tumor immune surveillance or to reverse the tumor immune escape. Different therapeutic strategies for ovarian carcinoma have evolved over the years. Already 30 years ago, the first clinical studies focused on modulating the tumor cytokine network with special attention to interferon-mediated immune responses. With the exploration of specific tumor antigens such as NY-ESO-1, which is expressed in ovarian carcinoma and other malignancies, the development of therapeutic cancer vaccines has been pursued initiating the era of personalized anti-cancer medicine. Almost at the same time, the adoptive transfer of genetically modified autologous tumor-reactive T-cells occurred, but response rates in ovarian carcinoma were disappointing. Today, probably the most promising therapeutic approach in this context is the blockade of immune checkpoints, such as programed cell death protein 1 (PD-1) and one of its ligands (PD-L1) or cytotoxic T-cell lymphocyte-associated antigen 4 (CTLA-4), which has demonstrated impressive response rates in malignant melanoma and non-small cell lung cancer. Despite increasing availability of treatment approaches that target tumor immune surveillance in ovarian carcinoma, selecting patient groups that particularly benefit from these treatment modalities is clinically challenging as predictive biomarkers are lacking. Here, we summarize different immunotherapy approaches in ovarian cancer and discuss why immunotherapy in ovarian cancer is still in its infancy.

The 34th Annual Meeting of the Korean Society of Gynecologic Oncology 2019: meeting report.

The 34th Annual Meeting of Korean Society of Gynecologic Oncology (KSGO) was held in Busan, Korea from 26 to 27 April. Around 460 Korean and international clinicians gathered in Busan to share and discuss their latest work and key issues of gynecologic oncologic research and treatment. The scope of this meeting included recent clinical trials and updates in gynecologic oncology, advances in ovarian cancer treatment, targeted therapy and immunotherapy in gynecologic cancer, management of hereditary gynecologic cancer, and newly revised staging of cervical cancer. As expected, the ongoing debate regarding the recent clinical trial on minimally invasive surgery for early-stage cervical cancer was addressed throughout the congress and the initial outline of the KSGO position statement was open for discussion. The meeting was an opportunity for all participants to come together and explore scientific insights of gynecologic cancer.

Soluble forms of immune checkpoint receptor PD-1 and its ligand PD-L1 in plasma of patients with ovarian neoplasms

Background:Ovarian cancer is one of the most common oncologic diseases holding the frst place in mortality related to neoplasms of female genitalia. Along with active surgical intervention, contemporary ovarian cancer treatment includes various chemotherapeutic regimens which in many cases are quite effective, but relapse and death rates still remain high. In the recent years, major attention has been paid to the possibility of ovarian cancer immunotherapy associated with the discovery of the so-called “immune checkpoint” signaling, i.e. programmed cell death-1 / programmed death-ligand 1 (PD-1/PD-L) pathway, controlling intensity and duration of autoimmune response at physiologic conditions. Tumor PD-1 and/or PD-L1 expression is being actively studied as a predictor of anti-PD-1/PD-L treatment efficacy; however, this approach has certain limitations and problems that might be probably bypassed by determination of soluble PD-1 (sPD-1) and its ligand (sPD-L1) in serum or plasma.Aim:Comparative evaluation of sPD-1 and sPD-L1 content in plasma of healthy women and of patients with benign or borderline ovarian tumors and ovarian cancer, as well as the analysis of associations between these markers and main clinical and pathologic characteristics of ovarian cancer.Materials and methods:Sixty two (62) patients with ovarian neoplasms aged 32 to 77 (median, 56.5) years were enrolled into the study. Fifteen (15) patients had benign tumors, 9 had borderline, and 38, ovarian cancer. The control group included 17 healthy women aged 24 to 67 (median, 49) years. Plasma sPD-L1 and sPD-1 concentrations were measured with standard enzyme immunoassay kits (Afmetrix, eBioscience, USA).Results:Plasma sPD-L1 and sPD-1 levels in ovarian cancer patients (median, 41.3 and 48.0 pg/ml, respectively) did not differ significantly from those in the control group (49.5 and 43.8 pg/ml). sPD-L1 level in the patients with benign tumors (median, 22.2 pg/ml) was signifcantly lower than in the control (p < 0.01). The lowest sPD-1 level in plasma was found in the patients with borderline ovarian neoplasms, the difference with the ovarian cancer group being statistically signifcant (p < 0.05). No correlations between sPD-L1 and sPD-1 plasma levels were found in any of the study groups. sPD-L1 level signifcantly increased with disease stage (R = 0.44; p < 0.01), the most signifcant increase being observed at the most advanced IIIC stage (p < 0.05 as compared to all other stages). sPD-L1 was also signifcantly higher in the patients with ascites than in those without ascites. Plasma sPD-1 concentration was not associated with the indices of ovarian cancer progression, though its median was 1.3–1.44 times lower in the stage I than in the stage II–III patients, and decreased in those with the tumor size above 10 cm (assessed by ultrasound examination) and in the patients with ascites. No statistically signifcant associations of the markers' levels with tumor histological type and differentiation grade of ovarian cancer were found.Conclusion:sPD-L1 level in ovarian cancer patients correlates with disease progression and can be considered as a promising marker for monitoring of anti-PD-1/PD-L1 treatment efficacy. Potential clinical implications of sPD-1 require further studies.

Ovarian Cancer-Intrinsic Fatty Acid Synthase Prevents Anti-tumor Immunity by Disrupting Tumor-Infiltrating Dendritic Cells.

Fatty acid synthase (FASN), the key metabolic enzyme of de novo lipogenesis, provides proliferative and metastatic capacity directly to cancer cells have been described. However, the impact of aberrant activation of this lipogenic enzyme on host anti-tumor immune milieu remains unknown. In this study, we depicted that elevated FASN expression presented in ovarian cancer with more advanced clinical phenotype and correlated with the immunosuppressive status, which characterized by the lower number and dysfunction of infiltrating T cells. Notably, in a mouse model, we showed that tumor cell-intrinsic FASN drove ovarian cancer (OvCa) progression by blunting anti-tumor immunity. Dendritic cells (DCs) are required to initiate and sustain T cell-dependent anti-tumor immunity. Here, our data showed that constitutive activation of FASN in ovarian cancer cell lead to abnormal lipid accumulation and subsequent inhibition of tumor-infiltrating DCs (TIDCs) capacity to support anti-tumor T cells. Mechanistically, FASN activation in ovarian cancer cell-induced the resulting increase of lipids present at high concentrations in the tumor microenvironment. Dendritic cells educated by FASNhigh OvCa ascites are defective in their ability to present antigens and prime T cells. Accordingly, inhibiting FASN by FASN inhibitor can partly restore the immunostimulatory activity of TIDCs and extended tumor control by evoking protective anti-tumor immune responses. Therefore, our data provide a mechanism by which ovarian cancer-intrinsic FASN oncogenic pathway induce the impaired anti-tumor immune response through lipid accumulation in TIDCs and subsequently T-cells exclusion and dysfunction. These results could further indicate that targeting the FASN oncogenic pathway concomitantly enhance anti-tumor immunity, thus offering a unique approach to ovarian cancer immunotherapy.

The Inhibition of Platelets Restore Anti-Tumor Immune Response to Ovarian Cancer and Its Therapeutic Implication

The interactions between platelets and cancer cells activate platelets and enhance tumor growth. The ability of a cancer cell line to activate platelets in vitro, tumor cell-induced platelet aggregation (TCIPA), predicts the in vivo aggressiveness of that particular cancer cell line. We have found that platelets extravasate into tumor microenvironment. We also have shown that ovarian cancer cells secret ADP that activate platelets by binding to P2Y12 (an ADP receptor on platelets). In turn, activated platelets enhance proliferation of ovarian cancer cells and tumor growth. Activated platelets release TGFβ to the tumor microenvironment (TME) that enhances cancer cell proliferation in a TGFβ dose-dependent manner. Platelet TGFβ also functions as an immune modulator by enhancing differentiation of T cells toward T-reg. Platelets not only increase cancer cell proliferation but also alter the immune response to cancer by suppressing the function of tumor-infiltrating T cells. The presence of tumor-infiltrating lymphocytes (TIL) is associated with a significant improvement in the progression-free survival (PFS) and the overall survival (OS) of patients with ovarian cancer. In the current study, we investigated the effect of platelet inhibition on promoting the immune response to tumors and the therapeutic benefit of combining anti-platelet reagents with checkpoint inhibitors (CPIs) in murine models of ovarian cancer.We have shown before, P2Y12 deficient (P2Y12-/-) and platelet specific TGFβ knockout (TGFβfl/fl;PF4-cre) mice developed smaller tumors compared to control tumor-bearing mice in a murine ovarian cancer model. To determine the effect of anti-platelet reagent in platelet extravasation into the TME, we counted the number of platelets in the TME in four groups of tumor-bearing mice: control, aspirin-treated (ASA), platelet infused (Plt) and aspirin-treated + platelet-infused (Asp Plt) mice. Platelet extravasation increased after platelet infusion and reduced after aspirin treatment. The groups with a higher number of extravasated platelets developed larger tumors compared to those with less extravasated platelets.We investigated the role of platelet in regulation of immune response to tumor using mice with platelet specific defects in murine models of ovarian cancer. We immune profiled tumors induced in mice with platelet-specific TGFβ deficiency, P2Y12 deficient mice, and aspirin or Ticagrelor-treated mice. Overall platelet functional defects was associated with an increase in the number of T cells, DC, MØ and NK and a decrease in the number of MDSCs in tumors..We investigated the effect of immune check point inhibitors (CPI) on growth of murine ovarian cancer. We administrated 200µg of combination of CPIs (anti-CTLA4/ anti-PD-L1) into tumor-bearing mice. Combined CPI therapy had a minimal effect on the tumor burden (control=0.53± 0.082g vs. CPIs=0.33± 0.04g, p=0.15). Although CPI-treatment increased the number of CD8 cells inside tumors, it also increased the expression of VISTA (a negative) with an overall non-significant effect on the tumor growth. To investigate the effect of platelet inhibition on expression of checkpoint regulatory proteins in the TME, the expression of VISTA was examined in the tumors resected from TGFβfl/fl; PF4-cre tumor-bearing mice by quantitative RT-PCR (qRT-PCR), and was compared to that in tumors resected from WT tumor bearing mice. Tumors from TGFβfl/fl; PF4-cre mice expressed less VISTA mRNA (control= 1 vs. TGFβfl/fl; PF4-cre= 0.04 ± 0.01, p < 0.0001). Interestingly, P2Y12 deficiency and antiplatelet reagents (ticagrelor and aspirin) also reduced expression of VISTA in tumors. This is the first evidence for the effect of platelet inhibition on the expression of a checkpoint regulator in tumors.We hypothesize that platelet inhibition enhances anti-tumor immune response and can be used as an adjuvant to checkpoint inhibitors in immunotherapies for ovarian cancer. DisclosuresNo relevant conflicts of interest to declare.

Bevacizumab Antibody Affinity Maturation to Improve Ovarian Cancer Immunotherapy: In Silico Approach

Ovarian cancer is one of the most lethal gynecologic cancers. The high mortality rate is due to lack of early symptoms and developing drug resistance. Immunotherapy has emerged as a promising approach to treatment of cancer. Bevacizumab is a recombinant humanized monoclonal IgG antibody against VEGF A that used in cancer immunotherapy, especially in ovarian cancer therapy. For a successful cancer immunotherapy the different features of therapeutic antibodies such as binding affinity should be improved. Increased affinity enhances the biological action of the antibody, which in turn improves the therapeutic effects. Furthermore, the increased antibody affinity can reduce the therapeutic dose of the antibody, resulting in lower toxicity and handling cost. Considering the importance of this issue, using in silico analysis, we aimed to find the important amino acids of the Bevacizumab antibody, and then replaced these amino acids with others to improve antibody binding affinity. Finally, we examined the binding affinity of antibody variants to antigens. In conclusion, the designed antibodies could be potential candidates for binding to antigens with improved affinity.

Overview of CD24 as a new molecular marker in ovarian cancer

Ovarian cancer (OC) is the fifth leading cause of cancer-related death among women. The high mortality rate is due to lack of early symptoms, late diagnosis, limited treatment options, and also emerging of drug resistance. Todays, molecular markers have become promising in tumor-targeted therapy. Several molecular markers have been known in OC immunotherapy. Identification of the specific molecular markers with prognostic significance is interested. CD24 is a small sialoglycoprotein which is localized in lipid rafts through its glycosylphosphatidylinositol (GPI) anchor. It has been reported that CD24 is overexpressed in many cancers including OC. Also, CD24 is identified as a cancer stem cell marker in OC. The CD24 expression is associated with the development, invasion, and metastasis of cancer cells. The exact role of CD24 in cancer cells is not clearly understood. Recently, CD24 has been identified as an independent prognostic marker of survival in patients with OC. In this study, we reviewed the molecular targets in OC immune-targeted therapy and also presented an overview of the new molecular marker CD24 and its association with the OC by reviewing the recent literature.

Antigen-specific active immunotherapy for ovarian cancer.

This is the second update of the review first published in the Cochrane Library (2010, Issue 2) and later updated (2014, Issue 9).Despite advances in chemotherapy, the prognosis of ovarian cancer remains poor. Antigen-specific active immunotherapy aims to induce tumour antigen-specific anti-tumour immune responses as an alternative treatment for ovarian cancer. Primary objective• To assess the clinical efficacy of antigen-specific active immunotherapy for the treatment of ovarian cancer as evaluated by tumour response measured by Response Evaluation Criteria In Solid Tumors (RECIST) and/or cancer antigen (CA)-125 levels, response to post-immunotherapy treatment, and survival differences◦ In addition, we recorded the numbers of observed antigen-specific humoral and cellular responsesSecondary objective• To establish which combinations of immunotherapeutic strategies with tumour antigens provide the best immunological and clinical results SEARCH METHODS: For the previous version of this review, we performed a systematic search of the Cochrane Central Register of Controlled Trials (CENTRAL; 2009, Issue 3), in the Cochrane Library, the Cochrane Gynaecological Cancer Group Specialised Register, MEDLINE and Embase databases, and clinicaltrials.gov (1966 to July 2009). We also conducted handsearches of the proceedings of relevant annual meetings (1996 to July 2009).For the first update of this review, we extended the searches to October 2013, and for this update, we extended the searches to July 2017. We searched for randomised controlled trials (RCTs), as well as non-randomised studies (NRSs), that included participants with epithelial ovarian cancer, irrespective of disease stage, who were treated with antigen-specific active immunotherapy, irrespective of type of vaccine, antigen used, adjuvant used, route of vaccination, treatment schedule, and reported clinical or immunological outcomes. Two reviews authors independently extracted the data. We evaluated the risk of bias for RCTs according to standard methodological procedures expected by Cochrane, and for NRSs by using a selection of quality domains deemed best applicable to the NRS. We included 67 studies (representing 3632 women with epithelial ovarian cancer). The most striking observations of this review address the lack of uniformity in conduct and reporting of early-phase immunotherapy studies. Response definitions show substantial variation between trials, which makes comparison of trial results unreliable. Information on adverse events is frequently limited. Furthermore, reports of both RCTs and NRSs frequently lack the relevant information necessary for risk of bias assessment. Therefore, we cannot rule out serious biases in most of the included trials. However, selection, attrition, and selective reporting biases are likely to have affected the studies included in this review. GRADE ratings were high only for survival; for other primary outcomes, GRADE ratings were very low.The largest body of evidence is currently available for CA-125-targeted antibody therapy (17 studies, 2347 participants; very low-certainty evidence). Non-randomised studies of CA-125-targeted antibody therapy suggest improved survival among humoral and/or cellular responders, with only moderate adverse events. However, four large randomised placebo-controlled trials did not show any clinical benefit, despite induction of immune responses in approximately 60% of participants. Time to relapse with CA-125 monoclonal antibody versus placebo, respectively, ranged from 10.3 to 18.9 months versus 10.3 to 13 months (six RCTs, 1882 participants; high-certainty evidence). Only one RCT provided data on overall survival, reporting rates of 80% in both treatment and placebo groups (three RCTs, 1062 participants; high-certainty evidence). Other small studies targeting many different tumour antigens have presented promising immunological results. As these strategies have not yet been tested in RCTs, no reliable inferences about clinical efficacy can be made. Given the promising immunological results and the limited side effects and toxicity reported, exploration of clinical efficacy in large well-designed RCTs may be worthwhile. We conclude that despite promising immunological responses, no clinically effective antigen-specific active immunotherapy is yet available for ovarian cancer. Results should be interpreted cautiously, as review authors found a significant dearth of relevant information for assessment of risk of bias in both RCTs and NRSs.

Abstract A37: Epigenetic modification of ovarian cancer immunogenicity

Abstract Background: Ovarian high-grade serous carcinoma (HGSC) remains a poor prognosis disease due to its late presentation and lack of “actionable” mutations to target pharmacologically. The host immune system, however, plays a pivotal role with the presence of cytotoxic T lymphocytes and chemokines that regulate T-cell trafficking both having positive effect on survival in preclinical and clinical studies. HGSC cells can achieve immune escape via epigenetic silencing of key immune-related genes, including via DNA methylation; when DNA methylation is pharmacologically reversed, genes involved in antigen presentation, receptor-dependent immune cell stimulation, and chemokine release are reactivated. One of these genes encodes the angiostatic chemokine Cxcl10, which is a T-lymphocyte attractant. In order to elucidate other potential epigenetic mechanisms directly or indirectly involved in Cxcl10 gene silencing, we will screen a library of novel epigenetic probes that target bromodomains, methyltransferases, demethylases, and others epigenetic pathways (Structural Genomic Consortium library). Aims: We will use Trp53-/- ID8 ovarian cancer cells to perform a medium-throughput screening of 40 novel epigenetic probes, measuring cxcl10 production, with the demethylating drug decitabine as positive control. Methods: Trp53-/- ID8 cells were treated with decitabine for up to 72 hours. Cell-cycle analysis was assessed via BrdU incorporation assay. Cytokine/chemokine transcription was assessed using RT2 profiler 84 gene chemo/cytokine PCR array (Qiagen), and verified using qRT-PCR. Acid-hydrolysed DNA was subjected to mass spectrometry/liquid chromatography to quantify the mean ratio of methyl-cytosine/cytosine. Western immunoblotting was performed to test DNMT1 protein levels in protein lysates after decitabine treatment. Cxcl10 levels in supernatant were quantified by ELISA. Results: Treatment of Trp53-/- ID8 cells with decitabine (DAC), at non-cytostatic/cytotoxic doses causes upregulation of multiple chemokines, specifically Cxcl10. 200nM DAC for 48 hours increased Cxcl10 transcription 22-fold (95% CI 20.6-21.1-fold, p=0.0001, values normalized to Gapdh control), and protein levels in supernatant three-fold (t test p&amp;lt;0.0001). At this dose, DNTM1, the target enzyme of DAC, is downregulated on Western-blot analysis, and the methyl-cytosine/cytosine ratio decreases significantly (means compared with t test, p =0.002). Other statistically significant upregulated chemokine genes are Cxcl1 (p=0.002), Cxcl3 (p&amp;lt;0.001), Cxcl4 (p&amp;lt;0.001), Cxcl5 (p=0.03), and Ccl4 (p=0.01). Conclusions: Abrogation of DNA methylation with DAC in Trp53-/- ID8 cells induces an increase in the chemokine cxcl10, at both transcriptional and protein level. This provides a robust control for a medium-throughput screening of other epigenetic modifiers that are still at an early drug development stage, such as probes against bromodomains, methyltransferases, and demethylases. Such screening can unmask novel epigenetic mechanisms involved in immune-related gene transcription and offer new ways to potentiate immunotherapy in ovarian cancer. Citation Format: Pavlina Spiliopoulou, Josephine Walton, Suzanne Dowson, Alex Binks, Oliver Maddocks, Peter Adams, Iain McNeish. Epigenetic modification of ovarian cancer immunogenicity. [abstract]. In: Proceedings of the AACR Conference: Addressing Critical Questions in Ovarian Cancer Research and Treatment; Oct 1-4, 2017; Pittsburgh, PA. Philadelphia (PA): AACR; Clin Cancer Res 2018;24(15_Suppl):Abstract nr A37.

Abstract IA22: Reprogramming the tumor microenvironment and T cells for ovarian cancer immunotherapy

Abstract Immunologic destruction of tumors is a multistep, coordinated process that can be modulated or targeted at several critical points to elicit tumor rejection. These steps in the cancer immunity cycle include: (i) generation of sufficient numbers of effector T cells with high avidity recognition of tumor antigens in vivo; (ii) trafficking and infiltration into the tumor; (iii) overcoming inhibitory networks in the tumor microenvironment; (iv) direct recognition of tumor antigens and generation of an effector antitumor response; and (v) persistence of the antitumor T cells. Although several immune-based interventions have gained regulatory approval in many solid tumors and hematologic malignancies, there are currently no approved immune therapies for ovarian cancer. A major barrier to successful deployment of cancer immunotherapy for ovarian cancer patients is the immunosuppressive tumor microenvironment. Even if large numbers of tumor-specific T cells are generated in patients by active immunization or adoptive transfer, these T cells may not persist to readily destroy tumor targets in vivo. Previous studies by our group have defined some of the dominant immune resistance mechanisms in ovarian cancer to include extrinsic suppression of CD8+ effector cells by regulatory T cells (Tregs) (1, 2); metabolic deregulation via tryptophan catabolism by the immunoregulatory enzyme indoleamine-2,3-dioxygenase (IDO) (3, 4); engagement of inhibitory receptors such as PD-1 by the ligand PD-L1/B7-H1 (5-7); development of antigen loss variants (8); myeloid-derived suppressor cells (9); and inhibitory cytokines such as TGF-β. Collectively, this redundant immunosuppressive network facilitates tumor progression by actively restraining antitumor immunity and must be overcome in order to implement efficacious immunotherapeutic strategies. This presentation will be focused on our efforts at: (i) overcoming IDO-mediated innate and adaptive immune resistance as a strategy to reprogram the ovarian tumor microenvironment and (ii) novel “next-generation” strategies for reprograming T cells for adoptive immunotherapy of ovarian cancer.