Abstract 4003: Improved drug screening and resistance monitoring using cancer organoids derived from dissociated tumor cells and circulating tumor cells

Abstract Cancer is a complicated disease, and despite recent breakthroughs in cancer treatment, cancer remains the second leading cause of death globally, with metastatic cancers responsible for the large majority. To develop effective cancer drugs, we need reliable in vitro models that represent cancers accurately, particularly for metastatic cancers. However, current experimental models of human cancers in vitro face several limitations. Well-established cell lines typically emerged from long-term exposure to simple tissue culture conditions, while genomic and epigenetic instability contribute to their drift away from the characteristics of the original tumors. Because of the significant heterogeneity both within each tumor and within each type of cancer, cell lines fail to represent the diversity of the disease. Even using a very large number of cell lines still restricts the results to cancers whose cells grow on plastic in relatively uncomplex media formulations. Aiming to overcome these limitations, we are leveraging a novel system for culturing tumor organoids. We culture tumor organoids from dissociated tumor cells (DTCs) from primary tumors, or circulating tumor cells (CTCs) from the blood of patients with solid tumors, in our proprietary culture platform. We have successfully cultured a wide range of DTC and CTC samples into tumor organoids, including samples from breast, colon, renal, lung, pancreatic, and prostate cancers, and we continue to add to the list. The successful expansion of these samples enables us to overcome the limited availability of such material and to apply methods typically reserved for cell line-based drug screening. We tested the drug sensitivity of these organoids to standard-of-care chemotherapeutics and other approved anticancer drugs, by cell viability assay. We also monitored organoid morphology longitudinally by brightfield microscopy during the treatment period. To evaluate drug resistance, we plated tumor organoids into Corning Elplasia plates, separating organoids into individual microcavities and enabling longitudinal tracking of each organoid throughout treatment. We continued culturing the surviving drug-resistant organoids after the treatment period and evaluated their changes in phenotype, morphology, mutation status, and gene expression. To characterize the resistance of individual organoids, we tested whether single-organoid RNA-Seq could provide more useful insights than bulk RNA-Seq. DTC- and CTC-derived organoids typically exhibit differing sensitivities in our drug sensitivity screening. Since CTC-derived organoids resemble metastatic cancers, this platform enables the evaluation of anti-metastatic cancer drug efficacy, representing a major improvement over the current system. Citation Format: Yi-chun Han, David Hsieh, Shian-Jiun (SJ) Shih. Improved drug screening and resistance monitoring using cancer organoids derived from dissociated tumor cells and circulating tumor cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2025; Part 1 (Regular Abstracts); 2025 Apr 25-30; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2025;85(8_Suppl_1):Abstract nr 4003.