LAUSR

Greater than 10 million patients succumb to cancer each year. Cancer metastasis is responsible for more than 90% of all cancer-associated deaths due to treatment resistance and increased tumor burden. As a seed for metastases, circulating tumor cells (CTCs) present a new dimension and horizon for clinical doctors in diagnosis, prognosis prediction, treatment monitoring, disease mechanism, and drug development. CTCs could gradually replace tissue biopsies which are painful and may be difficult to obtain depending on tumor location. CTC isolation is feasible after minimally invasive liquid biopsy and provides the basis for a multitude of ex vivo and in vivo studies including establishment of CTCs-derived 2D and 3D cultures. Organoids are miniscule models of tissues that grow in a 3D semisolid extracellular matrix medium with specific growth factors supplied. CTCs-derived 3D organoids play a vital role in precision oncology because they can preserve tumor heterogeneity, imitate the tumor microenvironment (TME), mimic cancer hypoxia in the TME, and maintain cancer and metastasis phenotypes. Cytotoxic CD8+ T cells are the most powerful effectors in the anticancer immune response. We hypothesized that co-culture of CTCs-derived 3D organoids and autologous cytotoxic CD8+ T cells could maximize patient-relevance of laboratory assessment of cancer-treatment immune-system interactions to facilitate precision oncology practice. TellBio’s novel TellDx CTC technology allows for isolation of viable and intact CTCs in liquid biopsies, regardless of cancer type. Unlabeled CTCs were cultured in growth factor reduced Matrigel with organoid culture WENRAS medium. Magnetic beads labeled white blood cells (WBCs) were cultured with T cell culture medium - WBCs and magnetic beads usually separate in three days - cytotoxic CD8+ T cells were isolated with the EasySep™ Human CD8+ T Cell Isolation Kit. CTCs-derived 3D organoids and autologous cytotoxic CD8+ T cells were co-cultured with or without different drug treatments - cytotoxicity was measured with CellTiterGlo® 3D Cell Viability Assay and imaging, and further mechanistic studies were feasible. Our co-culture platform enables us to utilize a patient's peripheral blood or pleural effusions to create a patient-specific, in vivo-like TME and immune microenvironment to model and assess ex vivo responses to investigational and FDA-cleared cancer therapies, and potentially provide oncologists with insights to improve clinical outcomes. Citation Format: Lanlan Zhou, Leiqing Zhang, Lindsey Carlsen, Kelsey E. Huntington, Vida Tajiknia, Andrew George, Arielle De La Cruz, Arunasalam Navaraj, Praveen Srinivasan, Maximilian Schwermann, Benedito A. Carneiro, Wafik S. El-Deiry. Co-culture of circulating tumor cells (CTCs)-derived 3D organoids and autologous cytotoxic CD8+ T cells: A new functional precision oncology platform [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 6706.