TMOD-06. Brain metastasis–induced neuroglial disruption: insights from a novel human organoid–brain slice co-culture model

Abstract BACKGROUND Brain metastases (BM) are the most common intracranial tumors, affecting over 170,000 individuals annually in the U.S., and are associated with significantly worse prognosis compared to other metastatic sites. Unlike primary tumors, BM evolve within the brain’s distinct cellular and immune environments, giving rise to unique tumor subpopulations with altered therapeutic responses. This study aimed to establish a patient-derived ex-vivo model to investigate how BM influence the surrounding brain parenchyma, with a focus on identifying mechanisms that contribute to neurological dysfunction beyond mere mass effect. METHODS Brain metastasis organoids (BMOs) were established from resected patient BM specimens and cultured with long-term viable human brain slices obtained from epilepsy disconnection surgeries. The interactions between BMOs and host brain tissue were monitored using fluorescent labeling live imaging. Transmission electron microscopy (TEM) and transcriptomic profiling were employed to characterize peritumoral alterations. Graph-based analysis and ligand-receptor interaction mapping were used to identify dysregulated signaling networks with therapeutic relevance. RESULTS TEM revealed localized axonal demyelination in patient resected peritumoral brain parenchyma—an effect not seen in glioblastoma or control tissues. BMOs integrated with brain slices and recapitulated key tumor behaviors. Transcriptomic profiling after 7 days of co-culture identified 1,247 differentially expressed genes, including significant downregulation of genes involved in myelination, synaptic transmission, and neurogenesis, along with upregulation of immune-related pathways. Network analysis identified critical regulators of neuronal and glial function, including a downregulated gene cluster essential for myelination (including MAG, PLP1,SOX10). Ligand-receptor analyses revealed alterations in BMP and TGF-β signaling. Comparisons with matched primary tumors showed distinct transcriptional reprogramming in BM. CONCLUSION This ex-vivo BMO–brain slice model faithfully replicates BM–brain interactions and uncovers tumor-induced molecular disruptions in brain tissue. It highlights actionable signaling pathways and serves as a platform for testing interventions aimed at preserving neurological function in patients with BM.