Abstract Prostate cancer (PCa) is the most frequently diagnosed cancer in men and metastasizes predominantly to bone, lymph node, liver, and lung. Liver metastasis has been shown to associate with the worst patient outcomes with a median overall survival of 13. 5 months and treatment options for metastatic castration resistant PCa are limited to chemotherapy. Retrospective analysis of liver metastatic biopsies identified an enrichment of genetic alterations in p53, Rb1, and PTEN tumor suppressor genes. Current pre-clinical models have limited capability to assess the effect of these genomic alterations on tumor progression in the liver tumor microenvironment (TME). Thus, there is a critical need to develop new models of liver metastatic PCa for discovery to identify transcriptomic profiles that associate with high-risk disease and assess potential therapeutic vulnerabilities. We report the development of a novel, fully humanized ‘tumor on a chip” model of the liver metastatic niche that incorporate human liver stroma and PCa organoids. We utilize a microfluidic platform, LumeNEXT, which allows 3D culture of multicellular TME networks in the context of an endothelial lined lumen. We have optimized media conditions to co-culture HepG2 hepatocytes, LNCaP tumor organoids and HUVEC endothelial cells in hydrogel matrix. Confocal microscopy is performed for live cell, multi-parameter analysis of spatio-temporal investigation of the liver TME. Direct, in-chip, live cell analysis of cell viability is performed with Hoechst nuclear labeling, Calcein AM and Ethidium homodimer staining. Culture conditions have been optimized to maintain 85% viability for each cell type after 3 days of co-culture. We demonstrated that HUVEC cells were able to form endothelial lined vessels that maintained 3D structure within this multi-cellular TME. This platform enables future testing of different cellular compositions of liver TME, including different immune cell and stromal populations. We are currently incorporating CRISPR engineered LNCaP cell lines with p53 and Rb1 loss to evaluate the functional impact of the liver TME in the context of high-risk genomic mutations. This novel model system may expedite discovery of the molecular drivers behind this aggressive form of disease and allow identification of targetable mechanisms to develop more effective treatment strategies to improve outcomes for patients with PCa liver metastasis. More recent iterations implement a normal hepatocyte model of THLE-2, SV40 immortalized normal hepatocytes, to replace HepG2, liver carcinoma cells. Future model development will include incorporating primary patient-derived liver cells such as hepatocytes, Kupffer cells and stellate cells, matched with prostate tumor cells for a personalized medicine approach to treatment strategies. Citation Format: Katherine Vietor, Erika Heninger, Gabriel Eades, Adeline B. Ding, Cristina Sanchez de Diego, David A. Quigley, Sheena C. Kerr, Joshua M. Lang. Development of a fully humanized vascularized "tumor on a chip" model for prostate cancer liver metastasis abstract. In: Proceedings of the AACR Special Conference in Cancer Research: Innovations in Prostate Cancer Research and Treatment; 2026 Jan 20-22; Philadelphia PA. Philadelphia (PA): AACR; Cancer Res 2026;86 (2Suppl): Abstract nr PR023.
Vietor et al. (Tue,) studied this question.