Background: Immuno-oncology drugs face the challenge that cell lines and animal models cannot recapitulate the full intimacies of the tumor microenvironment. Although these models have aided in the discovery of new medical modalities, only 8% of these models have had a successful translation. Furthermore, the phenotype of the microenvironment of various tumor types has not been assessed in depth. Nilogen Oncosystems' proprietary 3D-EX vivo drug screening platform analyzes fresh patient tumor tissue that remains embedded in its natural environment. With our model, the characteristics of the tumor microenvironment can be accurately revealed in response to checkpoint inhibitors in non-small cell lung cancer (NSCLC) and correlates can be found among different platforms.

Methods: For the 3D-EX vivo platform, microspheres were produced from procured fresh tumor tissue from NSCLC cancer patients. They were then treated with Keytruda ex vivo and treatment-mediated changes in TIL subpopulations were analyzed using flow cytometric analysis, cytokine release by Bio-Rad's 17-plex cytokine assay as well as gene expression by NanoString's 770 gene Immune Panel.

Results: Ex vivo treatment of the 3D microspheres with Keytruda, showed significant changes in T-cell activation and immune cell populations in 26% of NSCLC tumors. This was observed by the simultaneous increase in IFN-γ and TNF-α upon cytokine analysis. Furthermore, we found a differential expression of signature genes such as CD8, CXCL10, CXCL9, EOMES, Granzyme A/B, IFN-γ, related to T-cell subpopulations via Nanostring analysis, which was accompanied by an increase in Granzyme B via flow cytometry.

Conclusion: The positive and negative associations between expression of immune function genes, TIL activation, and cytokine production by ex vivo treatment shows that Nilogen Oncosystems' 3D-Ex vivo platform can accurately recapitulate the tumor microenvironment and exhibits the importance of a comprehensive analysis of the tumor immune microenvironment for a better understanding of the mechanism of action of immuno-oncology drugs that may aid in developing biomarkers that can be used for patient selection.

Citation Format: Melanie Mediavilla-Varela, Melba Marie Page, Jenny Kreahling, Soner Altiok. Characterization of the immune landscape and analysis of tumor response after anti-PD-1 blockade in a 3D ex vivo system of non-small lung cancer [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 1020.