Development of ex vivo patient-derived models to uncover the role of the tumor immune microenvironment in renal cell carcinoma 4463

Abstract Description With the rise of immune checkpoint inhibitors (ICIs) for the treatment of metastatic renal cell carcinoma (RCC), understanding the role of T cells in the tumor microenvironment (TME) is critical. Single-cell transcriptomics have provided insights into T cell phenotypes, but functional validation is needed to develop novel therapies. We developed a patient-derived tumor model (PDTM) to assess inhibitory immune interactions on T cell function and anti-tumor activity in the RCC TME. Fresh RCC tumor samples were minced into ∼1 mm3 pieces and cultured in an air-liquid interface system embedded in a collagen matrix with or without anti-PD-1 antibody. The PDTM system maintained the TME’s cellular architecture and immune composition over three days, as confirmed by immunohistochemistry and hematoxylin and eosin staining. Flow cytometry (FCM) identified well-preserved CA9+ tumor cells and immune cell populations, including CD4+ and CD8+ T cells, regulatory T cells, NK cells, B cells, and myeloid subsets. Anti-PD-1 treatment with low-dose T cell stimulation resulted in increased activated CD8 T cells (CD3+CD8+CD25+) by FCM and significantly increased IFN-γ production (p < 0.001, paired t-test) by ELISA, demonstrating PD-1 blockade’s functional relevance ex vivo. Our novel PDTM system preserves the RCC TME for functional interrogation and has extensive applications in studying RCC, including assessing the impact of ICIs and novel combination therapies on T cell function. Funding Sources This work was supported by DOD KCRP KC230003 and NIH grant 1R37CA279822-01. Topic Categories Tumor Immunology: Cellular Responses and Tumor Microevironment (TIME)