Ovarian Cancer Microenvironment Research Articles

Recent advances in understanding the immune microenvironment in ovarian cancer.

The occurrence of ovarian cancer (OC) is a major factor in women's mortality rates. Despite progress in medical treatments, like new drugs targeting homologous recombination deficiency, survival rates for OC patients are still not ideal. The tumor microenvironment (TME) includes cancer cells, fibroblasts linked to cancer (CAFs), immune-inflammatory cells, and the substances these cells secrete, along with non-cellular components in the extracellular matrix (ECM). First, the TME mainly plays a role in inhibiting tumor growth and protecting normal cell survival. As tumors progress, the TME gradually becomes a place to promote tumor cell progression. Immune cells in the TME have attracted much attention as targets for immunotherapy. Immune checkpoint inhibitor (ICI) therapy has the potential to regulate the TME, suppressing factors that facilitate tumor advancement, reactivating immune cells, managing tumor growth, and extending the survival of patients with advanced cancer. This review presents an outline of current studies on the distinct cellular elements within the OC TME, detailing their main functions and possible signaling pathways. Additionally, we examine immunotherapy rechallenge in OC, with a specific emphasis on the biological reasons behind resistance to ICIs.

Paracrine Ovarian Cancer Cell-Derived CSF1 Signaling Regulates Macrophage Migration Dynamics in a 3D Microfluidic Model that Recapitulates In Vivo Infiltration Patterns in Patient-Derived Xenografts.

A high density of macrophages in the ovarian cancer microenvironment is associated with disease progression and poor outcomes. Understanding cancer-macrophage interaction mechanisms that establish this pro-tumorigenic microenvironment is critical for developing macrophage-targeted therapies. Here, 3D microfluidic assays and patient-derived xenografts are utilized to define the role of cancer-derived colony stimulating factor 1 (CSF1) on macrophage infiltration dynamics toward ovarian cancer cells. It is demonstrated that multiple ovarian cancer models promote the infiltration of macrophages into a 3D extracellular matrix in vitro in a cell density-dependent manner. Macrophages exhibit directional migration and increased migration speed under both direct interactions with cancer cells embedded within the matrix and paracrine crosstalk with cancer cells seeded in an independent microchannel. It is also found that platinum-based chemotherapy increases macrophage recruitment and the levels of cancer cell-derived CSF1. Targeting CSF1 signaling under baseline or chemotherapy-treatment conditions reduces the number of infiltrated macrophages. It is further shown that results obtained with the 3D microfluidic model reflect the recruitment profiles of macrophages in patient-derived xenografts in vivo. These findings highlight the role of CSF1 signaling in establishing macrophage-rich ovarian cancer microenvironments, as well as the utility of microfluidic models in recapitulating 3D tumor ecosystems and dissecting cancer-macrophage signaling.

DC-Derived CXCL10 Promotes CTL Activation to Suppress Ovarian Cancer

This study investigates the role of dendritic cells (DCs), with a focus on their CXCL10 marker gene, in the activation of cytotoxic T lymphocytes (CTLs) within the ovarian cancer microenvironment and its impact on disease progression. Utilizing scRNA-seq data and immune infiltration analysis, we identified a diminished DC presence in ovarian cancer. Gene analysis pinpointed CXCL10 as a key regulator in OV progression via its influence on DCs and CTLs. Prognostic analysis and in vitro experiments substantiated this role. Our findings reveal that DC-derived CXCL10 significantly affects CTL activation and proliferation. Reduced CXCL10 levels hinder CTL cytotoxicity, promoting ovarian cancer cell migration and invasion. Experimental studies using animal models have provided further evidence that the capacity of CTLs to suppress tumor development is significantly diminished when treated with DCs that have low expression of CXCL10. Dendritic cell-derived CXCL10 emerges as a pivotal factor in restraining ovarian cancer growth and metastasis through the activation of cytotoxic T lymphocytes. This study sheds light on the crucial interplay within the ovarian cancer microenvironment, offering potential therapeutic targets for ovarian cancer treatment.

ALKBH5 modulates macrophages polarization in tumor microenvironment of ovarian cancer

BackgroundMacrophages play an essential role in regulating ovarian cancer immune microenvironment. Studies have shown that m6A methylation could influence immune microenvironment in cancer. In this study, we investigated the roles of m6A demethylase ALKBH5 and m6A recognition protein IGF2BP2 played in regulating macrophages polarization in ovarian cancer.MethodsIn this study, we first explored the differentially expressed m6A methylation enzymes in M0 and M2 macrophages according to two independent GEO datasets. TIMER2.0 and GSCA database were used to explore the immune analysis of ALKBH5 and IGF2BP2 in ovarian cancer. K-M plotter and TIMER2.0 databases were used to evaluate the prognostic role of ALKBH5 and IGF2BP2 in ovarian cancer. For CNV mutation analysis of ALKBH5 and IGF2BP2, cBioPortal and GSCA databases were used. For single-cell analysis, sc-TIME and HPA softwares were used to analyze the roles of ALKBH5 and IGF2BP2 played in immune cells in ovarian cancer. To identify the role of ALKBH5 played in macrophage polarization, RT-PCR was used to verify the macrophage polarization related markers in vitro study. The function of ALKBH5 played in ovarian cancer was further analyzed through GO and KEGG analysis.FindingsIn this study, we found that ALKBH5 and IGF2BP2 were up-regulated in M2 macrophages, which showed closely correlation with immune cells expressions in ovarian cancer, especially with macrophages. Ovarian cancer patients with higher expression of ALKBH5 and IGF2BP2 showed worse prognosis, possibly because of their close correlation with immune response. ALKBH5 also correlated with macrophage phenotypes in single-cell levels analysis. However, the expression level of IGF2BP2 in ovarian cancer immune microenvironment was very low. The results of RT-PCR indicated the potential role of ALKBH5 in M2 polarization of macrophages.InterpretationALKBH5 participated in regulating macrophage M2 polarization in ovarian cancer immune microenvironment.

CAR-T Cell Therapy in Ovarian Cancer: Where Are We Now?

The success of chimeric antigen receptor T-cell (CAR-T) therapies in the treatment of hematologic malignancies has led to the investigation of their potential in the treatment of solid tumors, including ovarian cancer. While the immunosuppressive microenvironment of ovarian cancer has been a barrier in their implementation, several early phase clinical trials are currently evaluating CAR-T cell therapies targeting mesothelin, folate receptor a, HER2, MUC16, and B7H3. Ongoing challenges include cytokine-associated and "on-target, off-tumor" toxicities, while most common adverse events include cytokine release syndrome, hemophagocytic lymphohistiocytosis/macrophage activation-like syndrome (HLH/MAS), and neurotoxicity. In the present review, we summarize the current status of CAR-T therapy in ovarian cancer and discuss future directions.

Immunotherapy and the ovarian cancer microenvironment: Exploring potential strategies for enhanced treatment efficacy.

Despite progress in cancer immunotherapy, ovarian cancer (OC) prognosis continues to be disappointing. Recent studies have shed light on how not just tumour cells, but also the complex tumour microenvironment, contribute to this unfavourable outcome of OC immunotherapy. The complexities of the immune microenvironment categorize OC as a 'cold tumour'. Nonetheless, understanding the precise mechanisms through which the microenvironment influences the effectiveness of OC immunotherapy remains an ongoing scientific endeavour. This review primarily aims to dissect the inherent characteristics and behaviours of diverse cells within the immune microenvironment, along with an exploration into its reprogramming and metabolic changes. It is expected that these insights will elucidate the operational dynamics of the immune microenvironment in OC and lay a theoretical groundwork for improving the efficacy of immunotherapy in OC management.

Relationships of SIGLEC family-related lncRNAs with clinical prognosis and tumor immune microenvironment in ovarian cancer

Long non-coding RNAs (lncRNAs) and Sialic acid-binding immunoglobulin-type lectin (SIGLEC) family members play an important role in proliferation, apoptosis, immune-cell activation and tumor development. However, the relationships of SIGLEC family-related lncRNAs with clinical prognosis and tumor immune microenvironment in ovarian cancer (OC) are still unclear. 426 SIGLEC family-related lncRNAs were obtained according to the screening criteria R > 0.4 and p < 0.05 using Pearson correlation analysis. A risk model contained AL133279.1, AL021878.2, AC078788.1, AC039056.2, AC008750.1 and AC007608.3 was conducted based on the univariate Cox regression analysis, a least absolute shrinkage and selection operator (LASSO) Cox regression and multivariate Cox regression analyses. OC patient were divided into high-and low-risk group based on the median riskscore. K–M curve and ROC curve revealed that risk model has an abuset prognostic potential for OC patients. Moreover, we successfully validated the prognostic value of the model in the internal datasets, external datasets and clinical sample dataset. Finally, we found that the riskscore was positively correlated with the vast majority of immune cell infiltration. In conclusion, our research identified that a novel SIGLEC family-related lncRNAs risk model to predict the prognosis of OC patients. SIGLEC family-related lncRNAs risk model also has a positive relationship with the tumor immune microenvironment of OC, which may provide a new direction for immunotherapy of OC.

High-dimensional deconstruction of ovarian cancer at single-cell precision reveals HEBP2 that reshape the TIME and drive carboplatin resistance

BackgroundSingle-cell sequencing was employed to analyze the tumor immune microenvironment in ovarian cancer (OC) patients, exploring the evolutionary roles of various macrophage subgroups in OC progression and their correlation with fatty acid metabolism-related genes in contributing to drug resistance. MethodsThis study aimed to decipher the mechanisms underlying OC chemoresistance (OC-CR) and carboplatin resistance by integrating and analyzing multiple single-cell RNA sequencing datasets from OC patients. The tumor immune microenvironment in OC-CR patients exhibited notable alterations in cellular interactions and the proportions of different immune cell populations, in contrast to the cohort sensitive to OC chemotherapy. ResultsThe study demonstrates that the fatty acid-associated gene HEBP2 not only accelerates OC progression but also modifies the immune landscape of OC, driving the polarization from M0_TAM to M2_TAM. This shift results in a diminished efficacy of chemotherapy in OC. Furthermore, both in vitro and in vivo experiments underscored HEBP2′s role in boosting the proliferation of OC-resistant cell lines and suppressing apoptosis, thereby facilitating carboplatin resistance. ConclusionIn conclusion, the immune microenvironments of OC-CR significantly differ from those sensitive to chemotherapy, underscoring HEBP2′s role in fostering OC resistance. This establishes HEBP2 as a promising prognostic marker and a novel target for therapeutic strategies against OC resistance.

Abstract 2894: Targeting NOS2 and the tumor microenvironment in endometrioid ovarian cancer: Implications for treatment and survival

Abstract Purpose of the study: The final aim of the study is to disrupt the deleterious effect of the tumor microenvironment by targeting inducible Nitric Oxide Synthase 2 (NOS2). NOS2 has a role in cancer cell proliferation and immune cells inactivation. It is upregulated by cytokines released from the tumor proinflammatory environment and the adipose tissue. By targeting and reverting NOS2 functions, we want to develop a therapeutic modality that inhibits endometrioid ovarian cancer (EOC) progression and reactivates the immune response in the ovarian cancer tumor microenvironment (OC-TME). Experimental procedures: We analyzed ovarian cancer patients’ cohorts using TNMPlot, Kaplan-Meier Plotter and The Human Protein Atlas. We simulated the tumor proinflammatory microenvironment by administering Interferon-gamma (IFN-ϒ, 25 ng/mL), Interleukin 1 Beta (IL1-β, 10 ng/mL), Tumor Necrosis Factor-alpha (TNF-α, 10 ng/mL) on A2780 EOC human cell line. We also administered conditioned media (CM) from breast fat adipose tissue to assess the influence of lipid components on cytokines release. After upregulating NOS2, we tested the efficacy of Cisplatin in combination with L-NMMA, a NOS2 inhibitor, on A2780 cells through proliferation assays using RealTime-Glo™ MT Cell Viability Assay (Promega®). In addition, to assess the immune landscape in ovarian cancer, we developed a syngeneic model administering ID8 cells (murine OC cell line) through intraperitoneal injection (IP) in C57BL/6 mice. Results: The findings indicated higher NOS2 RNA expression levels in tumors than in normal samples according to TNMPlot (p = 6.84e-01). KMPlotter analysis revealed that patients with high NOS2 expression treated with Cisplatin had a significantly shorter survival rate (10.64 months) compared to those with lower NOS2 expression (25 months, p = 0.0088). Patients untreated with Cisplatin and exhibiting high NOS2 expression also showed lower survival rates (11 months) than those with lower NOS2 expression (34 months, p = 0.056). Furthermore, cytokine treatments increased NOS2 protein levels in A2780 cells after 48 hours, and CM similarly elevated NOS2 protein levels. Subsequent administration of Cisplatin and Cisplatin + L-NMMA to cytokine-treated A2780 cells notably reduced cell proliferation by 85% and 89%, respectively. Conclusion: Taken together, our results showed the importance of a proinflammatory environment and adipose tissue in NOS2 upregulation. These findings show a potential correlation between endometriosis, obesity, and endometrioid ovarian cancer. With the development of an in vivo and in vitro model, we can gain a better understanding of the role of NOS2 in immune inactivation as well as in cell proliferation in EOC. Citation Format: Gianmarco Melone, Mailin Li, Ivonne Uzair, Maria Chervo, Karina Ortega, Wei Qian, Jianying Zhou, Liliana Guzman, Sean Hynes, Sharon Glynn, Christoforos Thomas, Polina Matre, Lewis Francis, Jenny Chang. Targeting NOS2 and the tumor microenvironment in endometrioid ovarian cancer: Implications for treatment and survival [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 2894.

Abstract 7551: Combined epigenetic therapy and immune checkpoint blockade drive reshaping of the tumor microenvironment of platinum resistant ovarian cancer

Abstract Introduction: Immunotherapy has demonstrated modest effectiveness for patients with platinum-resistant ovarian cancer, which is in part related to the immunosuppressive tumor microenvironment (TME) of ovarian cancers. Epigenetic modulators in combination with immune checkpoint inhibitors (ICIs) may represent a potential way to sensitize ovarian cancer to immunotherapy by TME reprogramming. Methods: We evaluated the effect of epigenetic modulation in combination with ICI by comprehensive transcriptomic analyses of serially biopsied platinum-resistant/refractory ovarian cancer. Leveraging serial tumor samples from 30 patients that received oral azacitidine and pembrolizumab in the TRIO026 phase II clinical trial (NCT02900560), we performed bulk RNA sequencing and direct digital counting of 770 target genes using molecular barcodes (nCounter, NanoString) for 72 serial tumor samples, prior to treatment initiation and 6 weeks on-therapy. RNA sequencing of ~200 million reads for each sample was used for differential gene expression and gene set enrichment analysis (GSEA) and cell type deconvolution. Target gene expression data was normalized and analyzed for differential gene and pathway expression. Results: Differential gene expression analyses revealed an upregulation of inflammatory and cytolytic genes (IFNG, GZMA and GZMH; FDR-adjusted p=0.0184) as well as the co-inhibitory molecule CTLA-4 (FDR-adjusted p=0.0184). GSEA revealed an enrichment of IFNG response, natural killer cell mediated cytotoxicity, neutrophil degranulation, inflammatory response, and antigen processing/presentation related gene sets on-therapy (FDR-adjusted p &amp;lt; 0.001). Target gene expression analyses orthogonally confirmed these findings, which were also concordant with pathway scoring analyses showing an increased score for immune inflammatory pathways such as INFG signaling (Wilcoxon rank sum test p=0.01). Immune cell subset deconvolution suggested TME reshaping driven by a greater density of intra-tumoral T cells on-therapy (Wilcoxon rank sum test p=0.012). Higher IFNG, CXCL13, CXCR5 expression, CD8 T cell and NK cell density were associated with longer time on treatment, both at baseline and at the on-therapy timepoint. GSEA revealed an upregulation of interferon gamma, adaptive immunity, antigen presentation as well as conserved immune response gene sets on-therapy, for the patients attaining longer time on-treatment. Conclusion: Combination epigenetic and immunotherapy induces an inflammatory response and reshaping of the tumor microenvironment that may enhance their clinical efficacy, highlighting the therapeutic potential of utilizing epigenetic modulators as a way to sensitize platinum-resistant ovarian cancer to immune checkpoint inhibition. Citation Format: Blair V. Landon, Guneet Kaleka, Archana Balan, Julia L. Boland, Christopher Cherry, Gavin Pereira, Cynthia Zahnow, Boris Winterhoff, Stephen Baylin, Victor E. Velculescu, Gottfried E. Konecny, John A. Glaspy, Valsamo Anagnostou. Combined epigenetic therapy and immune checkpoint blockade drive reshaping of the tumor microenvironment of platinum resistant ovarian cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 7551.

Abstract 4986: Single-cell multimodal characterization of ovarian cancer microenvironment under neoadjuvant niraparib treatment informs an effective therapeutic strategy of suppressing HRD-dependent eTreg hyper-expansion

Abstract Homologous recombination deficiency (HRD) is a widespread hallmark in cancer, rendering tumors susceptible to PARP inhibition. Despite this well-established tumor-intrinsic vulnerability, the effects of HRD and related therapies on the tumor microenvironment (TME) remain poorly understood. In this study, utilizing single-cell RNA and T cell receptor profiling (scRNA/TCR-seq), we characterized 79 high-grade serous ovarian cancer (HGSOC) samples, both pre- and post-treatment, from 46 patients treated with neoadjuvant niraparib or chemotherapy in a phase II clinical trial (NCT04507841). This effort established the most comprehensive HGSOC TME atlas to date, encompassing over 700,000 cells. By integrating multiplex immunofluorescence imaging, flow cytometry, and bulk TCR-seq data from additional tumors and matched peripheral blood samples, we systematically assessed HRD-induced and treatment-perturbed dynamics of tumor-infiltrating and circulating immune cells. Surprisingly, among over 120 cell states across 10 cell types, effector regulatory CD4+ T cells (eTreg) exhibited the strongest enrichment in treatment-naïve HRD tumors and a marked treatment-induced reduction. Further analyses of transcriptional states and clonal kinetics revealed HRD-driven functional coordination between eTregs and exhausted CD8+ T cells (Tex), both displaying uniquely heightened tumor reactivity signatures and clonal co-expansions. The intra-population heterogeneity analysis of Tregs and Texs further demonstrated an effectiveness gradient, wherein the terminal subsets had a greater presence in HRD and were reversed by both niraparib and chemotherapy treatments. Delineating the clonal evolution of Tregs and Texs, we identified their notable crosstalk with other tumor-infiltrating T cell populations while remaining remarkably isolated from the peripheral blood repertoire, in line with their terminally differentiated status. Furthermore, we observed widespread, chronic activation of interferon signaling across TME components, downstream of HRD. This orchestrated CD4+ T cell anergy induction into Tregs, mainly through direct engagement by cancer cells that upregulated MHC-II molecules but lacked essential co-stimulatory ligands. Finally, we experimentally validated a therapeutic strategy to conjunctively and effectively break down these factors in HGSOC by combining PARP inhibition and eTreg deletion through a humanized therapeutic anti-CCR8 antibody in multiple syngeneic HGSOC mouse models. Our study unravels a key immunoregulatory role of eTregs in the HGSOC TME amplified by HRD. These findings underscore the underappreciated value of eTreg-focused therapeutics as novel immunotherapies for HGSOC and other genomically unstable cancers. Citation Format: Yikai Luo, Yu Xia, Dan Liu, Xiong Li, Huayi Li, Yi Zhao, Ding Ma, Yong Fang, Han Liang, Qinglei Gao. Single-cell multimodal characterization of ovarian cancer microenvironment under neoadjuvant niraparib treatment informs an effective therapeutic strategy of suppressing HRD-dependent eTreg hyper-expansion [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 4986.

A lactate metabolism-related signature predicting patient prognosis and immune microenvironment in ovarian cancer.

Ovarian cancer (OV) is a highly lethal gynecological malignancy with a poor prognosis. Lactate metabolism is crucial for tumor cell survival, proliferation, and immune evasion. Our study aims to investigate the role of lactate metabolism-related genes (LMRGs) in OV and their potential as biomarkers for prognosis, immune microenvironment, and immunotherapy response. Ovarian samples were collected from the TCGA cohort. And 12 lactate-related pathways were identified from the MsigDB database. Differentially expressed genes within these pathways were designated as LMRGs, which undergo unsupervised clustering to identify distinct clusters based on LMRGs. Subsequently, we assessed survival outcomes, immune cell infiltration levels, Hallmaker pathway activation patterns, and chemotaxis among different subtypes. After conducting additional unsupervised clustering based on differentially expressed genes (DEGs), significant differences in the expression of LMRGs between the two clusters were observed. The differentially expressed genes were subjected to subsequent functional enrichment analysis. Furthermore, we construct a model incorporating LMRGs. Subsequently, the lactate score for each tumor sample was calculated based on this model, facilitating the classification of samples into high and low groups according to their respective lactate scores. Distinct groups examined disparities in survival prognosis, copy number variation (CNV), single nucleotide variation (SNV), and immune infiltration. The lactate score served as a quantitative measure of OV's lactate metabolism pattern and an independent prognostic factor. This study investigated the potential role of LMRGs in tumor microenvironment diversity and prognosis in OV, suggesting that LMRGs play a crucial role in OV progression and the tumor microenvironment, thus serving as novel indicators for prognosis, immune microenvironment status, and response to immunotherapy.

Abstract PR-009: Reconstructing the metastatic tumor microenvironment of high grade serous ovarian cancer using human multicellular in vitro models

Abstract Effective treatment of high grade serous ovarian cancer (HGSOC) still represents a clinical challenge. This is partially due to poor understanding of the complexity of this disease and the highly immunosuppressive tumor microenvironment (TME) that makes HGSOC resistant to most of the newly discovered therapies. The lack of relevant and physiological human in vitro models represents a major issue as the development of new treatments are mostly based on mouse models that do not fully recapitulate the human disease. In this study, we developed 3-dimensional (3D) human multicellular in vitro models using as a template and validation, data collected in a previous study that ‘deconstructs’ the metastatic TME of HGSOC. Our human 3D in vitro pentaculture (five cell types) model is composed of patient-derived primary adipocytes, fibroblasts and mesothelial cells isolated from macroscopic normal omentum – the primary site of metastasis in HGSOC – of women undergoing a gynaeco-oncology surgery, combined with different high grade serous malignant cell lines and monocytes isolated from healthy individuals. We found that the peripheral blood monocytes were able to differentiate and polarize to macrophages in our model in a similar way that observed in human HGSOC omental metastasis. Interestingly, our pentaculture models self-rearrange at the cellular level in a different way depending on the malignant cell line used in the culture. RNAseq analysis of the pentacultures showed that the different cultures clustered according to the malignant cell line used suggesting that malignant cells have a major influence on the transcriptome of the TME. Moreover, we demonstrated that our pentacultures partially replicated human biopsies: some of the macrophage and fibroblast clusters identified in a previous scRNAseq experiment on human HGSOC biopsies were also found in the pentacultures. We then confirmed the presence of some these macrophages clusters at the protein level. Finally, these pentacultures reproduce some of the actions of macrophage modifying drugs that have previously been shown in vivo. In conclusion, the study of the immunosuppressive TME of HGSOC in these human 3D in vitro models allows us to identify the contribution of different cell types to tumor growth and spread and provides us a semi-high throughput platform for therapeutic screening. Citation Format: Beatrice Malacrida, Samar Elorbany, Eleni Maniati, Rachel Bryan-Ravenscroft, Sophie L.P. Skingsley, Florian Laforets, Ranjit Manchanda, Frances R. Balkwill. Reconstructing the metastatic tumor microenvironment of high grade serous ovarian cancer using human multicellular in vitro models [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr PR-009.

Abstract IA006: Friend or foe: Reevaluating the therapeutic potential of monocytes and tumor-associated macrophages in ovarian cancer

Abstract The hostile tumor microenvironment in ovarian cancer is an active deterrent to the efficacy of immunotherapeutic agents such as immune checkpoint inhibitors, Chimeric Antigen Receptor (CAR) T-cells, and Bispecific T-cell Engagers (BiTEs). Tumor-associated macrophages (TAMs) and Myeloid-Derived Suppressor Cells (MDSCs) have been shown to promote an immunosuppressive metabolic and cytokine tumor microenvironment that is detrimental to cytotoxic effector T-cell activity in ovarian cancer. These immunosuppressive cells are also associated with poor prognostic outcomes. The ideal approach to modulating TAMs and MDSCs is unknown. Data from preclinical models support reprogramming these cells to a more inflammatory phenotype or removing them from the tumor microenvironment entirely. However, neither approach has translated to clinical benefits. We have previously demonstrated that CAR-T cells modified to secrete IL-18 exerted their therapeutic effects partly via polarization of bone marrow macrophages towards an M1 phenotype. We also found that the depletion of TAMs improved CAR-T cell efficiency, even when these CAR-T cells were co-modified to secrete IL-12. Because of the propensity for monocytes to be recruited to the ovarian cancer tumor microenvironment, we evaluated the efficacy of monocytes genetically modified to secrete BiTEs. First, we designed and evaluated BiTEs that recognize the retained portion of MUC16 (Muc16-ecto) and CD3+ T-cells and showed that these BiTEs were efficacious in vitro and in vivo in a xenograft model of ovarian cancer. We validated that monocytes transduced to secrete Muc16-specific BiTEs (Mono-BiTEs) could effectively lyse tumor cells in vitro and suppress xenograft ovarian cancer cells in vivo. Adding IFN-alpha and IFN-gamma to Mono-BiTEs significantly improved Mono-BiTEs antitumor efficacy over BiTE therapy or unmodified monocyte therapy alone. Adoptive cell therapy with genetically engineered autologous monocytes could provide an alternative approach to reprograming or eliminating myeloid-derived cells in ovarian cancer. Citation Format: Oladapo Yeku. Friend or foe: Reevaluating the therapeutic potential of monocytes and tumor-associated macrophages in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr IA006.

Abstract B067: Omentin: A novel immune modulator in the pro-inflammatory omental microenvironment of high-grade serous ovarian cancer

Abstract B067: Omentin: A novel immune modulator in the pro-inflammatory omental microenvironment of high-grade serous ovarian cancer

Abstract A080: CD8+T-cell interplay with myeloid cells as spatial determinant of chemotherapy response in the tumor microenvironment of metastatic high-grade serous ovarian cancer

Abstract Our goal was to characterize the effects of chemotherapy on the tumor microenvironment of high-grade serous ovarian cancer (HGSC) and suggest effective combination treatment strategies. We employed comprehensive multiomic spatial and single-cell profiling techniques, including tissue cyclic immunofluorescence t-CycIF, scRNA sequencing, and spatial transcriptomics (GeoMx) to characterize the tumor microenvironment of a total of 70 HGSC samples obtained from 41 patients from our prospective, observational trials (DECIDER, ONCOSYS-OVA). The longitudinal samples were collected before and after neoadjuvant chemotherapy (NACT), and they predominantly originated from intra-abdominal metastases. Utilizing cell type calls from whole slide t-CycIF high-dimensional marker expression data, we observed a significant increase in antigen presentation in IBA1+CD11c+ macrophages and CD11c+ myeloid cells interacting with CD4+ and interferon activated CD8+T-cells following NACT. These interactions formed spatial gradients within the tissues. To further investigate spatial heterogeneity, we identified recurring cellular neighborhoods using spatial clustering of cell types across all samples. These multicellular structures exhibited varying proportions of the 18 different cell types. Four out of five immune hotspot neighborhoods primarily comprised different myeloid cells. Interestingly, while the expression of the terminal exhaustion marker TIM3 did not differ in CD8+T-cells overall between the pre- and post-chemotherapy samples, TIM3 expression was specifically higher in CD8+T-cells in myeloid cell-rich neighborhoods from the post-chemotherapy samples, highlighting spatially restricted exhaustion patterns in HGSC. Notably, the most significant differences in overall cell type composition and cell-cell interaction patterns in samples collected before and after NACT were observed in the neighborhood corresponding to the tumor-stromal interface. CD8+T-cells exhibited higher-than-expected interactions with various myeloid cells, while their interactions with tumor cells were lower-than-expected, suggesting potential immune modulation following chemotherapy. Ligand-receptor analysis using paired site-matched scRNAseq data revealed upregulation of chemokines CXCL5 and CCL7 in macrophages after NACT, potentially induced by TNF from tumor cells. Spatial transcriptomics analysis provided further insights into the gene expression programs occurring between macrophages, CD8+T-cells, and tumor cells localized at the tumor-stromal interface. The prognostic power of the main findings were tested in bulk RNA-seq data from 33 patients treated with NACT. In conclusion, our findings indicate that the tumor microenvironment undergoes alterations following NACT, characterized by increased spatially coordinated interactions between CD8+T-cells and myeloid cells, particularly at the tumor-stromal interface. These insights contribute to a better understanding of the complex dynamics within the tumor microenvironment, facilitating the development of novel treatment strategies for HGSC. Citation Format: Inga-Maria P. Launonen, Erdogan P. Erkan, Iga Niemiec, Ada Junquera Mencía, Angela Szabo, Fernando Perez, Essi Kahelin, Sampsa Hautaniemi, Jaana Oikkonen, Johanna Hynninen, Anni Virtanen, Tuulia Vallius, Ajit J. Nirmal, Peter Sorger, Anna Vähärautio, Anniina Färkkilä. CD8+T-cell interplay with myeloid cells as spatial determinant of chemotherapy response in the tumor microenvironment of metastatic high-grade serous ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A080.

Abstract A102: ROR2/Wnt5a signaling regulates directional cell migration and early tumor cell invasion in ovarian cancer

Abstract Adhesion to and clearance of the mesothelial monolayer are key events in the early metastatic seeding of ovarian cancer. To identify mediators of ovarian cancer cell adhesion and invasion, we developed and conducted a cellular, high-throughput genetic screen using a human kinome siRNA library. Through this screen, we identified ROR2 as a driver of ovarian cancer adhesion and invasion. ROR2 is a receptor tyrosine kinase that interacts with Wnt5a ligand to activate non-canonical Wnt signaling and has been previously shown to be upregulated in ovarian cancer tissue. However, no prior study has evaluated the mechanistic role of ROR2 in ovarian cancer. Using in vitro adhesion and mesothelial clearance assays, we show that ROR2 promotes ovarian cancer cell adhesion and clearance of the mesothelial monolayer, key early steps in ovarian cancer metastasis. Further, we show that depletion of ROR2 reduces metastatic tumor burden in a syngeneic mouse model of ovarian cancer. Additionally, using a microfluidic device capable of producing stable fluid gradients, we demonstrate that ROR2 expression in ovarian cancer cells serves to drive directed cell migration of tumor cells, preferentially to areas of high Wnt5a ligand. As Wnt5a has been previously shown to be produced and upregulated in the mesothelial cells of the ovarian cancer microenvironment, these findings represent a novel role for ROR2 to promote the homing of ovarian tumor cells to the mesothelial lined metastatic niche by using Wnt5a as a chemotactic cue. These findings support the role of ROR2 as a critical factor contributing to the steps of ovarian cancer metastasis. Therapeutic targeting of the ROR2/Wnt5a signaling axis could provide a means of improving treatment for patients with advanced ovarian cancer. Citation Format: Whitney R. Grither, Breanna Baker, Vasilios A. Morikis, Katherine C. Fuh, Gregoery D Longmore. ROR2/Wnt5a signaling regulates directional cell migration and early tumor cell invasion in ovarian cancer [abstract]. In: Proceedings of the AACR Special Conference on Ovarian Cancer; 2023 Oct 5-7; Boston, Massachusetts. Philadelphia (PA): AACR; Cancer Res 2024;84(5 Suppl_2):Abstract nr A102.

HIF-2α-dependent TGFBI promotes ovarian cancer chemoresistance by activating PI3K/Akt pathway to inhibit apoptosis and facilitate DNA repair process

Hypoxia-mediated chemoresistance plays a crucial role in the development of ovarian cancer (OC). However, the roles of hypoxia-related genes (HRGs) in chemoresistance and prognosis prediction and theirs underlying mechanisms remain to be further elucidated. We intended to identify and validate classifiers of hub HRGs for chemoresistance, diagnosis, prognosis as well as immune microenvironment of OC, and to explore the function of the most crucial HRG in the development of the malignant phenotypes. The RNA expression and clinical data of HRGs were systematically evaluated in OC training group. Univariate and multivariate Cox regression analysis were applied to construct hub HRGs classifiers for prognosis and diagnosis assessment. The relationship between classifiers and chemotherapy response and underlying pathways were detected by GSEA, CellMiner and CIBERSORT algorithm, respectively. OC cells were cultured under hypoxia or transfected with HIF-1α or HIF-2α plasmids, and the transcription levels of TGFBI were assessed by quantitative PCR. TGFBI was knocked down by siRNAs in OC cells, CCK8 and in vitro migration and invasion assays were performed to examine the changes in cell proliferation, motility and metastasis. The difference in TGFBI expression was examined between cisplatin-sensitive and -resistant cells, and the effects of TGFBI interference on cell apoptosis, DNA repair and key signaling molecules of cisplatin-resistant OC cells were explored. A total of 179 candidate HRGs were extracted and enrolled into univariate and multivariate Cox regression analysis. Six hub genes (TGFBI, CDKN1B, AKAP12, GPC1, TGM2 and ANGPTL4) were selected to create a HRGs prognosis classifier and four genes (TGFBI, AKAP12, GPC1 and TGM2) were selected to construct diagnosis classifiers. The HRGs prognosis classifier could precisely distinguish OC patients into high-risk and low-risk groups and estimate their clinical outcomes. Furthermore, the high-risk group had higher percentage of Macrophages M2 and exhibited higher expression of immunecheckpoints such as PD-L2. Additionally, the diagnosis classifiers could accurately distinguish OC from normal samples. TGFBI was further verified as a specific key target and demonstrated that its high expression was closely correlated with poor prognosis and chemoresistance of OC. Hypoxia upregulated the expression level of TGFBI. The hypoxia-induced factor HIF-2α but not HIF-1α could directly bind to the promoter region of TGFBI, and facilitate its transcription level. TGFBI was upregulated in cisplatin-sensitive and resistant ovarian cancer cells in a cisplatin time-dependent manner. TGFBI interference downregulated DNA repair-related markers (p-p95/NBS1, RAD51, p-DNA-PKcs, DNA Ligase IV and Artemis), apoptosis-related marker (BCL2) and PI3K/Akt pathway-related markers (PI3K-p110 and p-Akt) in cisplatin-resistant OC cells. In summary, the HRGs prognosis risk classifier could be served as a predictor for OC prognosis and efficacy evaluation. TGFBI, upregulated by HIF-2α as an HRG, promoted OC chemoresistance through activating PI3K/Akt pathway to reduce apoptosis and enhance DNA damage repair pathway.

INHBA(+) cancer-associated fibroblasts generate an immunosuppressive tumor microenvironment in ovarian cancer

Effective targeting of cancer-associated fibroblasts (CAFs) is hindered by the lack of specific biomarkers and a poor understanding of the mechanisms by which different populations of CAFs contribute to cancer progression. While the role of TGFβ in CAFs is well-studied, less attention has been focused on a structurally and functionally similar protein, Activin A (encoded by INHBA). Here, we identified INHBA(+) CAFs as key players in tumor promotion and immunosuppression. Spatiotemporal analyses of patient-matched primary, metastatic, and recurrent ovarian carcinomas revealed that aggressive metastatic tumors enriched in INHBA(+) CAFs were also enriched in regulatory T cells (Tregs). In ovarian cancer mouse models, intraperitoneal injection of the Activin A neutralizing antibody attenuated tumor progression and infiltration with pro-tumorigenic subsets of myofibroblasts and macrophages. Downregulation of INHBA in human ovarian CAFs inhibited pro-tumorigenic CAF functions. Co-culture of human ovarian CAFs and T cells revealed the dependence of Treg differentiation on direct contact with INHBA(+) CAFs. Mechanistically, INHBA/recombinant Activin A in CAFs induced the autocrine expression of PD-L1 through SMAD2-dependent signaling, which promoted Treg differentiation. Collectively, our study identified an INHBA(+) subset of immunomodulatory pro-tumoral CAFs as a potential therapeutic target in advanced ovarian cancers which typically show a poor response to immunotherapy.

Aneuploid serves as a prognostic marker and favors immunosuppressive microenvironment in ovarian cancer

Ovarian cancer is the most lethal gynecologic neoplasm, and most patients experience recurrence and chemoresistance. Even the promising immunotherapy showed limited efficacy in ovarian cancer, probably due to the immunosuppressive microenvironment. However, the behind mechanisms of the immune exclusion or cold phenotype in ovarian cancer still remain to be explored. As a cancer dominated by copy number variations instead of mutations, ovarian cancer contains a high fraction of aneuploid, which might correlate with immune inhibition. Nevertheless, whether or how aneuploid affects ovarian cancer is still unclear. For exploring the role of aneuploid cancer cells and the potential ploidy-immune relationship, herein, the ploidy information was first comprehensively analyzed combining the karyotype data and copy number variation data obtained from Mitelman and cBioPortal databases, respectively. Ovarian cancer showed strong ploidy heterogeneity, with high fraction of aneuploid and recurrent arm-level and whole chromosome changes. Furthermore, clinical parameters were compared between the highly-aneuploid and the near-diploid ovarian cancers. Aneuploid indicated high grade, poor overall survival and poor disease-free survival in ovarian cancer. To understand the biofunction affected by aneuploid, the differentially expressed genes between the highly-aneuploid and the near-diploid groups were analyzed. Transcription data suggested that aneuploid cancer correlated with deregulated MHC expression, abnormal antigen presentation, and less infiltration of macrophages and activated T cells and higher level of T cell exclusion. Furthermore, the ploidy-MHC association was verified using the Human Protein Atlas database. All these data supported that aneuploid might be promising for cancer management and immune surveillance in ovarian cancer.