Abstract A089: Influence of pre-diagnosis aspirin use on epithelial ovarian cancer tumor immune microenvironment markers: results from the Nurses’ Health Study (NHS) and NHSII

Abstract Background: Daily aspirin use versus never use is associated with a 10-20% lower risk of developing epithelial ovarian cancer (EOC). Among women with EOC, aspirin use after diagnosis compared with never use is associated with a 30% improvement in ovarian cancer-specific survival. Inhibition of enzymes in prostaglandin synthesis is a key mechanism responsible for the anti-inflammatory and anti-neoplastic effects of aspirin. Prostaglandins influence immune inflammatory cells in the tumor microenvironment therefore our objective was to evaluate how aspirin use may influence the EOC tumor immune microenvironment. Methods: Tissue microarrays (TMAs) representing EOC tumor tissues from participants in the Nurses’ Health Study (NHS) and NHSII were assessed for total T cells, T cell activation and T cell exhaustion markers within the tumor (epithelium) area using multiplex immunofluorescence. Data on aspirin use and information on EOC risk factors and lifestyle variables were collected by questionnaire every two years. Beta-binomial models were used to estimate odds ratios (ORs) and 95% CIs; these models estimate the odds that a cell was positive for the marker (s) of interest comparing recent regular aspirin use (2+ times per week in the questionnaire cycle prior to diagnosis) versus never use, accounting for the total tumor cells in each core. Former users of aspirin were excluded. Multivariable models were adjusted for cohort, histotype (type 1 versus type 2), age and year of cancer diagnosis, number of CD3+ T cells (in tertiles), hysterectomy, tubal ligation, duration of oral contraceptive use, family history of breast or ovarian cancer, parity and body mass index (as fixed effects) and the participant (random effect) to account for multiple tissue cores per case. Results: We compared tumor tissues from 209 participants with recent pre-diagnosis use of aspirin with 88 participants who never used aspirin. Compared with cases who never used aspirin, recent aspirin users had higher odds of having tumors with recently activated cytotoxic T cells (CD3+CD8+CD69+, OR=1. 69, 95% CI: 1. 10, 2. 59) and T cells expressing exhaustion markers (CD3+Lag-3+, OR=1. 63, 95% CI: 1. 09, 2. 43; CD3+Tim-3+, OR= 1. 62, 95% CI: 0. 96, 2. 72). In contrast, there was no association between recent aspirin use versus never use and odds of a tumor being positive for total T cells (CD3+, OR=1. 20, 95% CI: 0. 80, 1. 79). Conclusions: Our data suggest that recent aspirin use before diagnosis was associated with higher odds of having EOC tumors expressing both recently activated cytotoxic T cells and T cell exhaustion markers. By improving our biological understanding of how aspirin use influences the ovarian tumor immune microenvironment, these results will assist to inform the optimal use of aspirin to improve EOC patient outcomes. Future work will focus on additional immune markers, assess non-aspirin nonsteroidal anti-inflammatory drug (NSAID) use and evaluate associations between aspirin/NSAID use with EOC survival considering the context of tumor immune microenvironment biomarkers. Citation Format: Nicola S. Meagher, Cassandra Hathaway, Mary K. Townsend, Mollie E. Barnard, Jose R. Conejo-Garcia, Brooke L. Fridley, Daryoush Saeed-Vafa, Britton Trabert, Shelley S. Tworoger, Melissa A. Merritt. Influence of pre-diagnosis aspirin use on epithelial ovarian cancer tumor immune microenvironment markers: results from the Nurses’ Health Study (NHS) and NHSII 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 Suppl₂): Abstract nr A089.