Abstract 935: Optimization of checkpoint inhibitor-TKI combinations in renal cell carcinoma using an ex vivo 3D tumor organoid model of fresh patient tissue with intact TME
Authors: Ehrhart Jared C. , Pabón Mibel M. , Agrawal Vijayendra , Pastoor Tina , Kreahling Jenny M. , Altiok Soner 
Published: September 2020

Abstract
Introduction: Renal Cell Carcinoma (RCC) is highly resistant to systemic chemotherapy. Different tyrosine kinase inhibitors (TKIs), such as sunitinib, sorafenib and axitinib have been introduced in the treatment of RCC with improved outcomes in the subsets of RCC patients. Tumor microenvironment (TME) plays a critical role in response to TKIs as well as to immuno-oncology drugs including the PD1 inhibitor nivolumab. Given the heterogeneity of the TME in each patient's tumor, optimization of combination treatments is highly desirable. Here, we employed an ex vivo 3D-tumor organoid model with unaltered TME to identify the most effective TKI-nivolumab combinations in individual RCC tumors and further explored the impact on both tumor cell viability and immune cell activation.
Materials and Methods: All RCC tumor samples were obtained with patient consent and relevant IRB approval. For the ex vivo assays 3D organoids measuring 150 micron in size were treated with sunitinib, sorafenib, axitinib alone or in combination with nivolumab ex vivo. Treatment-mediated changes in tumor immune cell composition including CD4 and CD8 T-cells, Tregs, NK cells, macrophages, cell surface expression of checkpoint proteins as well as T-cell activation were evaluated by multiplex flow cytometry. Multiplex cytokine assays were performed to assess drug-induced changes in cytokine release. High content confocal analysis was used to quantify tumor cell killing.
Results: We showed that TKI and nivolumab treatments alone had limited immune cell activation and tumor cell killing efficacy in RCC while their combination showed significant variations in T-cell activation by flow cytometry analysis and tumor cell killing by high content confocal imaging among different patient samples. We correlated tumor response to ex vivo treatments with tumor characteristics and further characterized the impact of treatment on TME in each tumor sample in an attempt to identify markers associated with drug responsiveness.
Conclusion: In this comprehensive study we used a physiologically relevant 3D tumor organoid model to demonstrate the impact of the heterogeneity of TME on TKI/nivolumab treatments in renal cell carcinoma. This approach can be used to identify the most effective drug and drug combinations in RCC and may improve personalized immunotherapy for individual patients in clinical studies.
Citation Format: Jared C. Ehrhart, Mibel M. Pabón, Vijayendra Agrawal, Tina Pastoor, Jenny M. Kreahling, Soner Altiok. Optimization of checkpoint inhibitor-TKI combinations in renal cell carcinoma using an ex vivo 3D tumor organoid model of fresh patient tissue with intact TME [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 935.