Background Advanced cancer causes necrosis and releases damage-associated molecular patterns (DAMPs). Mitochondrial DAMPs activate neutrophils, including generation of neutrophil extracellular traps (NETs), which are injurious, thrombogenic, and implicated in metastasis. We hypothesised that extracellular mitochondrial DNA (mtDNA) in ascites from patients with epithelial ovarian cancer (EOC) would correlate with worse outcomes. Methods Banked ascites supernatants from patients with newly diagnosed advanced EOC were analysed for mtDNA, neutrophil elastase, and activation of healthy donor neutrophils and platelets. TCGA was mined for expression of SELP and ELANE . Results The highest quartile of ascites mtDNA correlated with reduced progression-free survival (PFS) and a higher likelihood of disease progression within 12-months following primary surgery ( n = 68, log-rank, p = 0.0178 ). NETs were detected in resected tumours. Ascites supernatants chemoattracted neutrophils, induced NETs, and activated platelets. Ascites exposure rendered neutrophils suppressive, based on abrogation of ex vivo stimulated T cell proliferation. Increased SELP mRNA expression correlated with worse overall survival ( n = 302, Cox model, p = 0.02 ). Conclusion In this single-centre retrospective analysis, ascites mtDNA correlated with worse PFS in advanced EOC. Mitochondrial and other DAMPs in ascites may activate neutrophil and platelet responses that facilitate metastasis and obstruct anti-tumour immunity. These pathways are potential prognostic markers and therapeutic targets.

Objectives Epithelial ovarian cancer (EOC) typically presents with advanced disease. Even with optimal debulking and response to adjuvant chemotherapy, the majority of patients will have disease relapse. We evaluated cytokine and chemokine profiles in ascites at primary surgery as biomarkers for progression-free survival (PFS) and overall survival (OS) in patients with advanced EOC. Methods Retrospective analysis of patients (n =70) who underwent surgery at Roswell Park Cancer Institute between 2002-12, followed by platinum-based chemotherapy. Results The mean age at diagnosis was 61.8 years, 85.3% had serous EOC, and 95.7% had stage IIIB, IIIC, or IV disease. Univariate analysis showed that ascites levels of tumor necrosis factor (TNF)-α were associated with reduced PFS after primary surgery. Although the ascites concentration of interleukin (IL)-6 was not by itself predictive of PFS, we found that stratifying patients by high TNF-α and high IL-6 levels identified a sub-group of patients at high risk for rapid disease relapse. This effect was largely independent of clinical prognostic variables. Conclusions The combination of high TNF-α and high IL-6 ascites levels at primary surgery predicts worse PFS in patients with advanced EOC. These results suggest an interaction between ascites TNF-α and IL-6 in driving tumor progression and resistance to chemotherapy in advanced EOC, and raise the potential for pre-treatment ascites levels of these cytokines as prognostic biomarkers. This study involved a small sample of patients and was an exploratory analysis; therefore, findings require validation in a larger independent cohort.

Objectives The CD47 “don’t eat me” signal allows tumor immune evasion. We tested the association of CD47 expression with outcomes in EOC. Methods CD47 expression was examined within the TCGA database for ovarian carcinoma. For validation, IHC was performed on a TMA consisting of specimens from 265 patients with EOC. The medical records of the patients were also retrospectively reviewed to correlate demographic and survival data. Results CD47 was amplified in 15/316 (5%) ovarian serous cancers in TCGA. In the validation cohort, the majority of patients had stage III/IV disease (208/265, 78.4%). CD47 expression was seen in 210/265 (79.2%). Patients were categorized into CD47hi (129/265; 48.7%) versus CD47lo (136/265; 51.3%). Patients with CD47lo tumors were more likely to have a complete response to adjuvant therapy than CD47hi (65% vs 50%, p= 0.026). Although there was a trend towards an increase in median OS (37.64 vs 45.26 mos, p=0.92) in the CD47lo group compared with CD47hi, the difference was not significant. Conclusions CD47 is expressed at high frequency in EOC. Patients with CD47lo EOC had a better treatment response to standard therapy, and trended towards improved OS. This demonstrates that while CD47 may be an immunologic shield that may be considered for targeted therapies, it is likely that it operates in concert with other mechanisms of immune evasion. Future studies to evaluate CD47 expression with other known mechanisms of immune escape in the tumor microenvironment may help further define its role.

Epithelial ovarian cancer (EOC) is typically diagnosed at advanced stages, and is associated with a high relapse rate. Patients in remission are ideal candidates for immunotherapy aimed at cure or prolonging disease-free periods. However, immunosuppressive pathways in the tumor microenvironment are obstacles to durable anti-tumor immunity. In a metastatic syngeneic mouse model of EOC, immunosuppressive macrophages and myeloid-derived suppressor cells (MDSCs) accumulate in the local tumor environment. In addition, resident peritoneal macrophages from non-tumor-bearing mice were highly immunosuppressive, abrogating stimulated T cell proliferation in a cell contact-dependent manner. Immunization with microparticles containing TLR9 and NOD-2 ligands (MIS416) significantly prolonged survival in tumor-bearing mice. The strategy of MIS416 immunization followed by anti-CD11b administration further delayed tumor progression, thereby establishing the proof of principle that myeloid depletion can enhance vaccine efficacy. In patients with advanced EOC, ascites analysis showed substantial heterogeneity in the relative proportions of myeloid subsets and their immunosuppressive properties. Together, these findings point to immunosuppressive myeloid cells in the EOC microenvironment as targets to enhance vaccination. Further studies of myeloid cell accumulation and functional phenotypes in the EOC microenvironment may identify patients who are likely to benefit from vaccination combined with approaches that deplete tumor-associated myeloid cells.

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