Abstract B035: Evaluating drug sensitivity heterogeneity in cancer organoids derived from circulating tumor cells

Abstract Background: Drug resistance is a major challenge in cancer treatment, often driven by tumor cell heterogeneity. We cultivated circulating tumor cells (CTCs) from the blood of patients with solid tumors, including those preserved as frozen PBMCs, into cancer organoids. Two organoid lines, derived from renal and colon cancers, have been maintained and used extensively to assess drug sensitivity. During these experiments, viability assays revealed that a subset of organoids displayed resistance to certain drugs, resuming growth after initial inhibition. This prompted us to investigate this heterogeneity using specialized assays. Methods: To study variability in drug responses among CTC-derived organoids, we employed three complementary approaches: 1. Microcavity Plates: Corning's Elplasia plates with microcavities were used to segregate organoids, facilitating high-resolution, kinetic imaging for monitoring individual organoid growth and survival during drug treatment. 2. Image Analysis: Morphological changes in organoids during drug exposure were tracked using image analysis, allowing for the quantitation of resistant organoids and providing insights into variations in growth patterns and morphological changes. 3. Transcriptome Profiling: Using individual organoids, each with sufficient RNA for analysis, allowed detailed transcriptomic profiling and provided a comprehensive assessment of genetic responses in drug-resistant organoids. Results: Preliminary results from a limited set of one renal and one colon cancer organoids indicate that the three methods we employed show promise in detecting heterogeneity in drug sensitivity. The use of Elplasia plates allowed for consistent kinetic monitoring of individual organoid survival, and image analysis effectively captured morphological changes associated with varying drug responses. Initial transcriptomic profiling hinted at distinct genetic signatures in drug-resistant organoids, suggesting a potential reflection of physiological heterogeneity seen in patient tumors, potentially including metastatic ones. While these findings are encouraging, further studies with more samples are needed to confirm these observations and refine our approach. Conclusion and Future Directions: Our integrated approach appears to be promising in identifying and characterizing drug sensitivity heterogeneity in CTC-derived cancer organoids. We plan to expand this study to include more patient samples and cancer types, aiming to confirm our findings and identify potential biomarkers of resistance. Citation Format: Yi-chun Han, David Hsieh, Shian-Jiun Shih. Evaluating drug sensitivity heterogeneity in cancer organoids derived from circulating tumor cells [abstract]. In: Proceedings of the AACR Special Conference in Cancer Research: Functional and Genomic Precision Medicine in Cancer: Different Perspectives, Common Goals; 2025 Mar 11-13; Boston, MA. Philadelphia (PA): AACR; Cancer Res 2025;85(5 Suppl):Abstract nr B035.