Abstract 34: A high-content imaging platform for quantitative assessment of immunogenic tumor cell killing and T-cell proliferation in 3D tumoroids of fresh patient tumor samples

Abstract Introduction: Challenges in the development of immunotherapeutics still remain due to the lack of clinically relevant drug screening platforms that recapitulate the complexity of the tumor immune microenvironment. T-cell activation and immunogenic tumor cell death have been the most desired assay readouts to fully explore the efficacy of immuo-oncology drugs and to develop most effective rational drug combinations. Conventional cytotoxicity assays such as Cr51 and LDH release assays are limited in providing clinically relevant data about treatment mediated tumor cell killing by immune cells. Here, we describe a novel 3D live tumor explant model of fresh patient tumor tissue (3D-EXplore) to simultaneously and cost effectively evaluate T-cell activation and tumor cell killing by immuno-oncology drugs. Materials and Methods: All human tumor samples were obtained with patients’ consent and relevant IRB approval. Fresh patient tumor samples of various cancer types (lung, bladder, kidney) were processed to generate unpropagated 3D tumoroids of standard size (100-150 microns). 3D tumoroids were treated with pembrolizumab (Keytruda) and atezolizumab (Tecentriq) alone or in combination with conventional chemotherapeutic drugs. Various combinations of viability, vitality, cell proliferation and cell death fluorogenic dyes were utilized to label tumor cells prior to high content confocal imaging. Treatment-mediated changes in tumor cell death and T-cell activation were quantified by Nilogen’s QTDI-algorithm. The results were corroborated by multiplex flow cytometry and cytokine relase assays. Results: 3D-tumoroids were successfully prepared from different tumor types. Tumor cell viability and immune cell composition including CD4 and CD8 T-cells, Tregs, NK cells and M1/M2 macrophages were monitored over 5 days to ensure obtaining reliable results. Using high-content image analysis and flow cytometric analysis, in selected tumors we observed a significant increase in T-cell activation and tumor cell killing upon ex vivo treatment with pembrolizumab or atezolizumab alone, which was enhanced in the presence of carboplatin. Conclusion: Here we have described a cost-effective and rapid drug testing platform using clinically relevant unpropogated fresh patient tumor tissue for rapid testing of multiple drugs and drug combinations based on tumor cell killing and T-cell activation to accelerate drug discovery, which can be applied in clinical studies to improve personalized immunotherapy for individual patients. Citation Format: Melanie Mediavilla-Varela, Vijayendra Agrawal, Melba Marie Page, Jenny Kreahling, Soner Altiok. A high-content imaging platform for quantitative assessment of immunogenic tumor cell killing and T-cell proliferation in 3D tumoroids of fresh patient tumor samples [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 34.