Abstract LB-347: Integrated Comprehensive Analysis of Immune Cell Subsets and Assessment of Checkpoint Inhibitor Response in Head and Neck Squamous Cell Carcinoma, Urothelial Carcinoma and Renal Cell Carcinoma 3D Ex Vivo
Authors: Page Melba Marie , Varela Melanie Mediavilla , Kreahling Jenny , Altiok Soner 
Published: August 2018

Abstract
Background: Since FDA approval in 2014, PD-1 blocking antibodies including Keytruda (pembrolizumab) have been used in the treatment of different types of malignancies including head and neck squamous cell, urothelial and renal cell carcinoma. Each solid tumor type not only varies patient-to-patient, but also varies in its heterogeneity, including but not limited to, its immune cell infiltrate. The impact of checkpoint inhibitor treatment on tumor immune landscape is not fully understood in solid tumors. In this study, we used an integrated comprehensive strategy to interrogate tumor immune cell compositions and T-cell activation in intact tumors before and after ex vivo treatment with checkpoint inhibitors utilizing Nilogen Oncosystems' 3D-EX drug screening platform.
Methods: For the 3D-EX platform, 3D tumor microspheres were produced from fresh head and neck squamous cell carcinoma, urothelial carcinoma and renal cell carcinoma tumor tissue obtained from consented patients at the time of surgical resection. Flow cytometry, Nanostring's PanCancer Immune Profiling Panel and bioplex multiplex human cytokine assay were used to analyze tumor immune microenvironment and treatment-mediated changes by checkpoint inhibitors.
Results: The flow cytometry analysis revealed a significant heterogeneity in immune cell composition (TILs, macrophages and MDSCs), T-cell activation status and checkpoint expressions between different tumor types. In our studies tumor responses to treatment ex vivo varied significantly for each tumor types, as assessed by activation of CD8 and CD4 T-cells by flow. Furthermore, Nanostring analysis revealed increased expression of genes involved in T-cell activation as well as genes with compensatory regulatory functions such as IDO1, LAG3, TIM3 and PD-L1 in tumor samples responsive to treatment ex vivo. Bioplex cytokine assays performed on the media demonstrated increased release of cytokines such as IFNg, TNFa, IL2, IL1b, IL6, GM-CSF and MIP1 that closely correlated with T-cell activation.
Conclusion: 3D-EX platform can successfully detect checkpoint inhibitor-mediated activation in T-cells within microspheroids prepared from surgical samples obtained from fresh patient tumors. 3D-EX platform is versatile and provide valuable information on mechanisms involved in drug sensitivity and resistance. This approach might aid in development of rational mechanism-based combination strategies to block compensatory signaling mechanisms to impart clinical benefit.
Citation Format: Melba Marie Page, Melanie Mediavilla Varela, Jenny Kreahling, Soner Altiok. Integrated Comprehensive Analysis of Immune Cell Subsets and Assessment of Checkpoint Inhibitor Response in Head and Neck Squamous Cell Carcinoma, Urothelial Carcinoma and Renal Cell Carcinoma 3D Ex Vivo [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr LB-347.