Abstract Background and Objective: Brain metastasis is a devastating complication in advanced cancers, particularly in breast cancer, where it significantly reduces patient survival. Despite its clinical relevance, early detection remains a challenge due to the absence of reliable biomarkers. Tumor-derived extracellular vesicles (EVs), key mediators of intercellular communication, have emerged as potential indicators of metastatic progression. This study aims to investigate whether EVs from breast cancer patients with brain metastasis possess pro-metastatic traits and could serve as predictive biomarkers for brain metastatic potential. Methods: Peripheral blood samples were collected from three groups: breast cancer patients with brain metastasis (n=10), primary breast cancer patients without metastasis (n=10), and healthy controls (n=10). EVs were isolated and profiled for epithelial-mesenchymal transition (EMT) -related gene expression (FN1, Vimentin, HIF1, VEGFA, CD44, SNAIL1, and TWIST1) using qRT-PCR. Functional validation was performed by incubating MDA-MB-231 cells with patient-derived EVs, followed by assays for EV uptake, proliferation, migration, invasion, cell cycle distribution, and gene expression. Results: EVs from brain metastatic patients showed significantly elevated expression of EMT markers compared to primary breast cancer and healthy controls. MDA-MB-231 cells efficiently internalized these EVs, which led to increased cell proliferation, migration, invasion, and EMT gene expression. Alterations in cell cycle phases were also observed, supporting a more aggressive phenotype post-EV exposure. Conclusion: Our findings suggest that circulating EVs from brain metastatic patients contribute to metastatic progression and may aid in forming a pre-metastatic niche, possibly facilitating blood-brain barrier disruption. This EV-based model offers a novel approach for predicting brain metastasis, enhancing current understanding beyond the traditional “seed and soil” hypothesis. EV profiling could become a valuable tool in non-invasive cancer diagnostics and metastasis prediction. Citation Format: Vinal Upadhyay, Kinjal Bhadresha, Rakesh Rawal. PREDICTING BRAIN METASTASIS THROUGH TUMOR-DERIVED EXTRACELLULAR VESICLES: ADVANCING THE SEED AND SOIL PARADIGM abstract. In: Proceedings of Frontiers in Cancer Science 2025; 2025 Nov 5-7; Singapore. Philadelphia (PA): AACR; Cancer Res 2026;86 (13Suppl): Abstract nr P34.
Upadhyay et al. (Thu,) studied this question.