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Low-grade serous ovarian carcinoma (LGSC) is a rare and lethal subtype of ovarian cancer. LGSC is pathologically, biologically, and clinically distinct from the more common high-grade serous ovarian carcinoma (HGSC). LGSC arises from serous borderline ovarian tumours (SBTs). The mechanism of transformation for SBTs to LGSC remains poorly understood. To better understand the biology of LGSC, we performed whole proteome profiling of formalin-fixed, paraffin-embedded tissue blocks of LGSC (n = 11), HGSC (n = 19), and SBTs (n = 26). We identified that the whole proteome is able to distinguish between histotypes of the ovarian epithelial tumours. Proteins associated with the tumour microenvironment were differentially expressed between LGSC and SBTs. Fibroblast activation protein (FAP), a protein expressed in cancer-associated fibroblasts, is the most differentially abundant protein in LGSC compared with SBT. Multiplex immunohistochemistry (IHC) for immune markers (CD20, CD79a, CD3, CD8, and CD68) was performed to determine the presence of B cells, T cells, and macrophages. The LGSC FAP + stroma was associated with greater abundance of Tregs and M2 macrophages, features not present in SBTs. Our proteomics cohort reveals that there are changes in the tumour microenvironment in LGSC compared with its putative precursor lesion, SBT. These changes suggest that the tumour microenvironment provides a supportive environment for LGSC tumourigenesis and progression. Thus, targeting the tumour microenvironment of LGSC may be a viable therapeutic strategy. © 2024 The Pathological Society of Great Britain and Ireland., (© 2024 The Pathological Society of Great Britain and Ireland.)

Background: For patients with high grade serous carcinoma of the ovary (HGSC), survival rates have remained static for the last half century. Despite the presence of tumor mutations and infiltration of immune cells, existing immunotherapies have achieved little success against HGSC. These observations highlight a gap in the understanding of how the immune system functions and interacts within HGSC tumors., Methods: We analyzed duplicate core samples from 939 patients with HGSC to understand patterns of immune cell infiltration, localization, and associations with clinical features. We used high-parameter immunohistochemical/Opal multiplex, digital pathology, computational biology, and multivariate analysis to identify immune cell subsets and their associations with HGSC tumors., Results: We defined six patterns of cellular infiltration by spatially restricted unsupervised clustering of cell subsets. Each pattern was represented to some extent in most patient samples, but their specific distributions differed. Overall (OS) and progression-free survival (PFS) corresponded with higher infiltration of CD16a + cells, and their co-localization with macrophages, T cells, NK cells, in one of six cellular neighborhoods that we defined with our spatial assessment., Conclusions: Immune cell neighborhoods containing CD16a+ cells are associated with improved OS and PFS for patients with HGSC. Patterns of immunologic neighborhoods differentiate patient outcomes, and could inform future, more precise approaches to treatment., Competing Interests: Author AM is employed by Akoya Biosciences. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest., (Copyright © 2024 Nersesian, Arseneau, Mejia, Lee, Westhaver, Griffiths, Grantham, Meunier, Communal, Mukherjee, Mes-Masson, Arnason, Nelson and Boudreau.)

High-grade serous ovarian cancer (HGSC) is frequently characterized by homologous recombination (HR) DNA repair deficiency and, while most such tumors are sensitive to initial treatment, acquired resistance is common. We undertook a multiomics approach to interrogate molecular diversity in end-stage disease, using multiple autopsy samples collected from 15 women with HR-deficient HGSC. Patients had polyclonal disease, and several resistance mechanisms were identified within most patients, including reversion mutations and HR restoration by other means. We also observed frequent whole-genome duplication and global changes in immune composition with evidence of immune escape. This analysis highlights diverse evolutionary changes within HGSC that evade therapy and ultimately overwhelm individual patients., (© 2023. The Author(s), under exclusive licence to Springer Nature America, Inc.)

Purpose: Tumor-infiltrating lymphocytes (TIL) are strongly associated with survival in most cancers; however, the tumor-reactive subset that drives this prognostic effect remains poorly defined. CD39, CD103, and PD-1 have been independently proposed as markers of tumor-reactive CD8 + TIL in various cancers. We evaluated the phenotype, clonality, and prognostic significance of TIL expressing various combinations of these markers in high-grade serous ovarian cancer (HGSC), a malignancy in need of more effective immunotherapeutic approaches., Experimental Design: Expression of CD39, CD103, PD-1, and other immune markers was assessed by high-dimensional flow cytometry, single-cell sequencing, and multiplex immunofluorescence of primary and matched pre/post-chemotherapy HGSC specimens., Results: Coexpression of CD39, CD103, and PD-1 ("triple-positive" phenotype) demarcated subsets of CD8 + TIL and CD4 + regulatory T cells (Treg) with a highly activated/exhausted phenotype. Triple-positive CD8 + TIL exhibited reduced T-cell receptor (TCR) diversity and expressed genes involved in both cytolytic and humoral immunity. Triple-positive Tregs exhibited higher TCR diversity and a tumor-resident phenotype. Triple-positive TIL showed superior prognostic impact relative to TIL expressing other combinations of these markers. TIGIT was uniquely upregulated on triple-positive CD8 + effector cells relative to their CD4 + Treg counterparts., Conclusions: Coexpression of CD39, CD103, and PD-1 demarcates highly activated CD8 + and CD4 + TIL with inferred roles in cytolytic, humoral, and regulatory immune functions. Triple-positive TIL demonstrate exceptional prognostic significance and express compelling targets for combination immunotherapy, including PD-1, CD39, and TIGIT., (©2021 American Association for Cancer Research.)

Objective: We recently showed that tumors with an immunologically 'cold' phenotype are enriched for expression of stemness-associated genes and PVR/CD155, the ligand of the immunosuppressive molecule TIGIT. To explore the therapeutic implications of this finding, we investigated the relationship between PVR/CD155 expression, tumor-infiltrating lymphocytes (TIL), and prognosis in high-grade serous ovarian cancer (HGSC) and other cancers., Methods: Expression of CD155, TIGIT, PD-1, PD-L1, and other immune markers in HGSC was assessed by high-dimensional flow cytometry, multi-color histological imaging, and/or gene expression profiling. The prognostic significance of PVR/CD155 and CD274/PD-L1 expression was assessed bioinformatically in HGSC and 32 other cancers in The Cancer Genome Atlas., Results: T cells from HGSC frequently co-expressed TIGIT and PD-1, and the ratio of TIGIT to PD-1 expression increased markedly after in vitro expansion with a clinically relevant protocol. CD155 was commonly expressed on malignant epithelium in HGSC and showed a negative or non-significant association with TIL. In contrast, PD-L1 was predominantly expressed by tumor-associated macrophages and positively associated with TIL. These contrasts between CD155 and PD-L1 were seen across HGSC patients, across metastatic sites within individual patients, and even within individual tumor deposits. PVR/CD155 and CD274/PD-L1 exhibited divergent prognostic associations across diverse cancer types in TCGA, including HGSC., Conclusions: CD155 and PD-L1 exhibit contrasting expression patterns, TIL associations and prognostic significance, suggesting they represent non-redundant immunosuppressive mechanisms. The CD155/TIGIT pathway represents a compelling immunotherapeutic target for HGSC and for immunologically cold tumors in general., Competing Interests: Declaration of competing interest No potential conflicts of interest to disclose., (Crown Copyright © 2020. Published by Elsevier Inc. All rights reserved.)

Purpose: Women with epithelial ovarian cancer generally have a poor prognosis; however, a subset of patients has an unexpected dramatic and durable response to treatment. We sought to identify clinical, pathological, and molecular determinants of exceptional survival in women with high-grade serous cancer (HGSC), a disease associated with the majority of ovarian cancer deaths. Experimental Design: We evaluated the histories of 2,283 ovarian cancer patients and, after applying stringent clinical and pathological selection criteria, identified 96 with HGSC that represented significant outliers in terms of treatment response and overall survival. Patient samples were characterized immunohistochemically and by genome sequencing. Results: Different patterns of clinical response were seen: long progression-free survival (Long-PFS), multiple objective responses to chemotherapy (Multiple Responder), and/or greater than 10-year overall survival (Long-Term Survivors). Pathogenic germline and somatic mutations in genes involved in homologous recombination (HR) repair were enriched in all three groups relative to a population-based series. However, 29% of 10-year survivors lacked an identifiable HR pathway alteration, and tumors from these patients had increased Ki-67 staining. CD8 + tumor-infiltrating lymphocytes were more commonly present in Long-Term Survivors. RB1 loss was associated with long progression-free and overall survival. HR deficiency and RB1 loss were correlated, and co-occurrence was significantly associated with prolonged survival. Conclusions: There was diversity in the clinical trajectory of exceptional survivors associated with multiple molecular determinants of exceptional outcome in HGSC patients. Concurrent HR deficiency and RB1 loss were associated with favorable outcomes, suggesting that co-occurrence of specific mutations might mediate durable responses in such patients. Clin Cancer Res; 24(3); 569-80. ©2017 AACR See related commentary by Peng and Mills, p. 508 ., (©2017 American Association for Cancer Research.)

Objective: As a negative regulator of T cells, Programmed Death Ligand 1 (PD-L1) is both an indicator and inhibitor of anti-tumor immune responses, which has led to confusion about its prognostic significance. We investigated the primary source of PD-L1 expression in epithelial ovarian cancer and its relationship to tumor-infiltrating lymphocytes (TIL) and associated gene products., Methods: Tissue microarrays containing high-grade serous carcinomas (HGSC) and endometrioid, clear cell and mucinous ovarian cancers from optimally debulked patients were assessed by immunohistochemistry for expression of PD-L1 and other markers (CD68, CD3, CD8, PD-1, CD103, FoxP3 and CD25). The Cancer Genome Atlas was interrogated for associations between PD-L1 expression and immune-related transcriptional and genomic features of HGSC., Results: PD-L1 was primarily expressed by tumor-associated CD68(+) macrophages rather than tumor cells. PD-L1(+) cells frequently co-localized with CD8, CD4 and PD-1(+) TIL, CD25(+)FoxP3(+) Tregs, and other TIL subsets. PD-L1(+) cells were prognostically favorable in HGSC. Moreover, the presence of both PD-L1(+) cells and CD8 TIL was associated with better prognosis than CD8 TIL alone. PD-L1 gene expression was independent of BRCA status. At the transcriptional level, PD-L1 was associated with both cytolytic (granzyme B, T-bet and IFN-γ) and suppressive (PD-1, CTLA-4, LAG3 and IDO-1) gene products., Conclusions: PD-L1 is primarily expressed by macrophages in ovarian cancer and is strongly associated with both cytolytic and regulatory TIL subsets, resulting in a net positive association with survival. Tumors containing PD-L1(+) macrophages appear caught in an immunological stalemate that may require multi-pronged immunotherapy to alleviate., (Crown Copyright © 2016. Published by Elsevier Inc. All rights reserved.)

Background: The presence of CD8(+) tumor-infiltrating lymphocytes (TIL) is associated with prolonged survival in high-grade serous ovarian cancer (HGSC) and other epithelial cancers. Survival is most strongly associated with intraepithelial versus intrastromal CD8(+) TILs; however, the mechanisms that promote the intraepithelial localization of TILs remain poorly understood. We hypothesized that intraepithelial CD8(+) TILs, like normal mucosal intraepithelial lymphocytes, might express CD103, a subunit of αE/β7 integrin, which binds E-cadherin on epithelial cells., Methods: A large collection of primary ovarian tumors (HGSC, endometrioid, mucinous, and clear cell) was analyzed by immunohistochemistry for the presence of TIL-expressing CD103. The activation and differentiation status of CD103(+) TILs were assessed by flow cytometry. The prognostic significance of TIL subsets was evaluated by Kaplan-Meier analysis., Results: CD103(+) TILs were present in all major ovarian cancer subtypes and were most abundant in HGSC. CD103(+) TILs were preferentially localized to epithelial regions of tumors and were comprised predominantly of CD8(+) T cells expressing activation (HLA-DR, Ki-67, PD-1) and cytolytic (TIA-1) markers, as well as CD56(+) NK cells. Tumor infiltration by CD103(+) TILs was strongly associated with patient survival in HGSC. Tumors containing CD8(+) TILs that were CD103(-) showed poor prognosis equivalent to tumors lacking CD8(+) TILs altogether., Conclusions: CD103(+) TILs comprise intraepithelial, activated CD8(+) T cells, and NK cells and are strongly associated with patient survival in HGSC. CD103 may serve as a useful marker for enriching the most beneficial subsets of TILs for immunotherapy., (©2013 AACR.)

Background: When T cells infiltrate the tumor environment they encounter a myriad of metabolic stressors including hypoxia. Overcoming the limitations imposed by an inadequate tumor vasculature that contributes to these stressors may be a crucial step to immune cells mounting an effective anti-tumor response. We sought to determine whether the functional capacity of tumor infiltrating lymphocytes (TIL) could be influenced by the tumor vasculature and correlated this with survival in patients with ovarian cancer., Methodology and Principal Findings: In 196 high-grade serous ovarian tumors, we confirmed that the tumor vascularity as measured by the marker CD31 was associated with improved patient disease-specific survival. We also found that tumors positive for markers of TIL (CD8, CD4 and forkhead box P3 (FoxP3)) and T cell function (granzyme B and T-cell restricted intracellular antigen-1 (TIA-1)) correlated significantly with elevated vascularity. In vitro, hypoxic CD8 T cells showed reduced cytolytic activity, secreted less effector cytokines and upregulated autophagy. Survival analysis revealed that patients had a significant improvement in disease-specific survival when FoxP3 expressing cells were present in CD31-high tumors compared to patients with FoxP3 expressing cells in CD31-low tumors [HR: 2.314 (95% CI 1.049-5.106); p = 0.0377]. Patients with high vascular endothelial growth factor (VEGF) expressing tumors containing granzyme B positive cells had improved survival compared to patients with granzyme B positive cells in VEGF-low tumors [HR: 2.522 (95% CI 1.097-5.799); p = 0.0294]., Significance: Overall, this data provides a rationale for developing strategies aimed at improving the adaptability and function of TIL to hypoxic tumor conditions.

Introduction: Tumor-infiltrating CD8(+) T cells are strongly associated with survival in high-grade serous ovarian cancer, but their functional phenotype remains poorly defined. The mucosal integrin CD103 (alpha(E)/beta(7)) facilitates the infiltration of T cells into epithelial tissues, including gut and lung mucosa, solid organ allografts, and various epithelial cancers. We reasoned that CD103 might also be expressed by tumor-reactive T cells in ovarian cancer., Methods: Flow cytometry was used to assess the frequency and phenotype of CD103-expressing T cells in primary ascites fluid from 13 patients with high-grade serous ovarian cancer and 2 patients with recurrent disease., Results: We report that a subset of patients with advanced serous ovarian cancer have profoundly elevated frequencies of CD103-expressing CD8(+) cells in ascites (between 20% and 70% of CD8(+) cells in ascites were CD103(+)) and that CD103 expression correlated with levels of TGF-beta in ascitic fluid. Conversely, CD103 was not expressed on CD4(+) cells, even in those patients with very high frequencies of CD8(+)CD103(+) cells. CD8(+)CD103(+) cells were antigen-experienced (CD45RA(-)CD45RO(+)CD62L(lo)CCR7(-)) and of an intermediate (EM2) effector memory phenotype (CD27(+)CD28(-)). TCR repertoire analysis indicated significant skewing between CD8(+)CD103(-) and CD8(+)CD103(+) T cell subsets, suggesting the two populations contain distinct antigenic specificities. Lastly, HLA pentamer analysis revealed that one patient in the cohort harbored a high frequency of CD8(+) T cells in ascites that were specific for the tumor antigen NY-ESO-1, and that approximately 75% of these NY-ESO-1 specific CD8(+) T cells were CD103(+)., Conclusions: CD103(+) may be a marker of activated and tumor-reactive CD8(+) T cells in high-grade serous ovarian cancer., (Copyright 2010 Elsevier Inc. All rights reserved.)