Abstract 3874: Engineered microphysiological systems for testing effectiveness of cell-based cancer immunotherapies in small cell lung cancer

Abstract Background: Immune cell trafficking into solid tumors has proven challenging due to immune cell exclusion by vascular barriers. Additionally, testing next-generation immune therapies remains difficult in animal models and requires sophisticated ex vivo systems to study human tumor biology and predict treatment response in real time. SCLC comprises approximately 15% of all lung cancer cases and despite recent incorporation of immune checkpoint blockade (ICB) into first line treatment, patients with SCLC continue to have a poor prognosis and limited treatment options. Notably, recent transcriptomic profiling of SCLC has indicated significant inter-tumoral and intra-tumoral heterogeneity. We have previously demonstrated that neuroendocrine SCLC subpopulations downregulate MHC I, whereas non-neuroendocrine SCLC subpopulations exhibit increased innate immune signaling and robust upregulation of MHC I antigen presentation. Here we interrogate the vulnerability of SCLC populations to NK cells and investigate their trafficking using a novel microphysiological ex vivo model. Methods: We developed a 3-dimensional (3D) microphysiological TME model of vascularized SCLC, comprising tumor spheroids embedded in a microvascular network self-assembled by endothelial cells and lung fibroblasts. Real time fluorescence imaging, cell-titer Glo and flow cytometry were used to quantify tumor cell viability in 2D and 3D microfluidic co-culture cytotoxicity assays, using primary NK cells and the NK92 cell line. Results: We demonstrated robust targeting of MHC-I low SCLC cells by primary human NK cells and NK92, and found that MHC-I high SCLC subpopulations show resistance to NK cell-mediated killing. To dissect the influence of vascular barriers on immune cell trafficking, we developed a 3D microphysiological TME model of vascularized SCLC, which successfully recapitulated tumor-vascular-immune interactions in a human-relevant platform as evidenced by vascular perfusion by NK cells. Using this model, we were able to demonstrate that the activation of cGAS-STING signaling in endothelial cells results in the secretion of CXCL10 and upregulation of adhesion molecules (ICAM-1, VCAM-1, E-selectin), promoting immune cell recruitment. Conclusions: We successfully developed a 3D microphysiological model of vascularized SCLC TME and show proof of principle that this model can be used for preclinical studies of cell therapies. Using this novel microphysiological system, we revealed that co-opting STING signaling can promote NK cell recruitment to the SCLC TME. Taken together, we show that microphysiological systems can be used to identify and test therapeutic vulnerabilities while studying immune infiltration and killing in the TME, offering an accurate and adaptable platform for biologic discovery and therapeutic development. Citation Format: Marco Campisi, Minyue Chen, Nathaniel Spicer, Patrick Lizotte, Erik H. Knelson, Cloud P. Paweletz, David A. Barbie, Navin R. Mahadevan. Engineered microphysiological systems for testing effectiveness of cell-based cancer immunotherapies in small cell lung cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2022; 2022 Apr 8-13. Philadelphia (PA): AACR; Cancer Res 2022;82(12_Suppl):Abstract nr 3874.