Abstract 1072: The EsomiR project: A case control study to assess the role of exosomal miRNAs in breast cancer cancerogenesis

Abstract Introduction: One of the unmet needs in Breast Cancer (BC) prevention is how to identify women at higher risk of developing this disease, who might benefit from periodic surveillance and/or from chemoprevention. The goal of this retrospective study is to assess the role miRNAs isolated from extracellular vesicles (EV-miRNAs) as possible early biomarkers for identifying patients with higher risk of developing BC, in order to personalize their screening programme. To this goal, EV-miRNAs from cyst fluid derived from women with Gross Cyst Disease of the Breast (GCDB - a benign disease of the mammary gland associated with a 2-4-fold increase in the risk of developing BC) have been analysed. Methodology: Cyst fluids have been selected among samples from a cohort of 600 patients diagnosed with GCDB between 1985 and 1993, some of whom developed BC during follow-up. EV-miRNAs have been extracted from cyst fluid using the exoRNeasy midi kit (Qiagen), qualitatively evaluated by Bioanalyzer (Agilent) and quantified by Qubit™ using the microRNA Assay Kit (Thermo Fisher Scientific). The MiRNome profiles have been assessed by microarray using an optimised protocol on Agilent platform (labelling and hybridization on SurePrint Human miR Microarrays 8 × 60 K and images acquisition by G2565CA scanner). Results: A total of 117 samples (58 cases and 59 controls, paired on the bases of clinical and pathological variables) have been analysed. Single variable logistic regression analysis on the most expressed EV-miRNAs (logFC = 6 (n=329) ), selected six EV-miRNAs (miR-6076, miR-202-3p, miR-6872-3p, miR-769-3p, miR-5195-3p, miR-4443) and one (miR-4713-3p) negatively and positively associated with BC development, respectively (raw p-value 0. 05). A risk score combining the seven EV-miRNAs was derived by multivariable logistic regression modelling and reported an AUC=0. 73 (95% CI 0. 6427-0. 8231). The model was refined including clinical variables and applying step-wise logistic regression analysis. The combination of 3 EV-miRNAs (miR-6076, miR-6872-3p, miR-5195-3p) with menopausal status, familiarity and type of cyst yielded an AUC of 0. 8 (95% CI 0. 7015-0. 8847). Logistic regression was also performed on Type I cysts (n=78), that are correlated with a higher risk of developing BC, pointing in evidence 3 EV-miRNAs with a negative (miR-6076, miR-6872-3p) or positive (miR-4515) correlation with BC development risk (AUC = 0. 74, 95% CI 0. 6278-0. 8475). In the model comprehensive of clinical variables, two of those EV-miRNAs (miR-6872-3p, miR-4515) together with familiarity and menopausal status were selected, giving an AUC of 0. 8 (95% CI 0. 6961-0. 8991). Conclusion: This study allowed the identification of a EV-miRNA-based BC risk signature obtained by liquid biopsy on cyst fluid. The final purpose of this project is to transfer this signature in the clinic by testing it prospectively on plasma samples. Citation Format: Barbara Cardinali, Patrizia Piccioli, Francesco Boccardo, Alessandra Rubagotti, Linda Zinoli, Andrea Sciutto, Simona Coco, Giovanna Chiorino, Paola Ostano, Emir Sehovic, Zita Cavalieri, Cristina Bruzzo, Silvia Marconi, Roberta Tasso, Rodolfo Quarto, Davide Ceresa, Paolo Malatesta, Lucia Del Mastro. The EsomiR project: A case control study to assess the role of exosomal miRNAs in breast cancer cancerogenesis 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 (6Suppl): Abstract nr 1072.