Abstract 4570: Expanding the 3D ex vivo patient tissue platform toolbox for (immuno)-oncology drug testing
Authors: Beztsinna Nataliia , Basten Sander , Aksoy Ezgi Kaya , Meesters Niels , Timiliotis Stefanos , van der Meer Donny , Yan Kuan , Spanjaard Emma , Vader Willemijn , Price Leo S. 
Published: April 2023

Abstract
Introduction: The fast-paced (immuno)-oncology drug development pipeline requires sophisticated and reliable in vitro models to accurately represent all players of complex human tumor microenvironment (TME). Our 3D Ex Vivo Patient Tissue (EVPT) platform is a short-term 3D ex vivo culture system utilizing ultra-fresh human tumor material processed to preserve the rich TME with high content image (HCI) analysis for higher throughput screening. The EVPT platform has previously been validated for standard of care (SoC) and immunological drug testing, including immune checkpoint inhibitors (ICI), in ovarian and non-small cell lung cancer (NSCLC) samples. Here, we present the expansion of the EVPT platform to other cancer indications, including resections from bladder, prostate, breast cancer, melanoma, glioblastoma (GBM) and hepatocellular carcinoma (HCC).
Methods: Tumor tissues from NSCLC, ovarian, bladder, prostate, breast cancer, melanoma, GBM and HCC patients were processed within 24 hours. Freshly isolated tumor clusters were embedded in a protein-rich hydrogel and exposed to panels of (immuno)-oncology treatments at various doses in a 384-well format for 5-7 days. Phenotypic effects of treatment on morphological features, such as tumor cell killing, growth arrest, and immune cell proliferation, were measured using our proprietary automated HCI platform. Whole blood samples were also collected and PBMCs were isolated for autologous co-culture assays with selected cancer samples. Additionally, biomarkers analysis, including IHC, FACS and cytokine measurements, was performed.
Results: At least two patient samples per new indication were processed. The success rate of the assay (30-40%) was primarily dependent on the sample quality, and the absence of necrotic, healthy, or fibrotic tissue within the sample. Panels of SoC drugs, targeted therapies, immunotherapies, and control compounds established for each indication were profiled per patient sample. For example, prostate cancer samples responded to Paclitaxel and Crizotinib, and one of GBM samples showed sensitivity to Regorafenib and Bevacizumab. Overall, similarly to clinical findings, about 20% of NSCLC and bladder cancer samples responded to ICI treatment, while 60-70% of the samples have responded to immunostimulatory controls (SEA and CD3/CD28).Although TME composition varied between NSCLC samples, IHC and FACs analysis showed a rich representation of immune compartment - T Cells (CD3+CD4+, CD3+CD8+), NK cells (CD16+), myeloid cells (CD14+, CD68+) alongside with EpCAM+ tumor cells.
Conclusion: Despite tissue quality remaining a challenge for many primary ex vivo assays, the gentle processing and short-term 3D culturing in our EVPT platform preserves the rich TME in a wide range of tumors. This makes our EVPT platform an innovative and translational tool for complex (immuno)-oncology drug testing in multiple cancer indications.
Citation Format: Nataliia Beztsinna, Sander Basten, Ezgi Kaya Aksoy, Niels Meesters, Stefanos Timiliotis, Donny van der Meer, Kuan Yan, Emma Spanjaard, Willemijn Vader, Leo S. Price. Expanding the 3D ex vivo patient tissue platform toolbox for (immuno)-oncology drug testing. [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 4570.