Vascular STING activation facilitates NK cell anti-tumor immunity in small cell lung cancer [scRNA-seq]
Small cell lung cancer (SCLC) typically displays a "cold" tumor microenvironment with a paucity of immune infiltrate. Neuroendocrine SCLC cells also profoundly repress MHC-I expression, rendering them vulnerable to NK cell-mediated cytotoxicity. Here, we confirm that neuroendocrine SCLC cells are sensitive to NK cell mediated attack, yet quantitative spatial profiling of the SCLC immune microenvironment in patient samples reveals that effector immune cells, including NK cells, are excluded from MHC-Ilow/neg SCLC regions. To study this biology, we develop dynamic single cell RNA sequencing of microphysiological immune tumor environments (DynaMITE-seq) and integrate findings with spatial transcriptomics in patient tissue, unveiling the microvasculature as a major checkpoint restricting NK cell extravasation/recruitment. We demonstrate that activation of vascular Stimulator of Interferon Genes (STING) signaling restores NK cell infiltration and killing of neuroendocrine SCLC, suggesting a strategy to overcome this key SCLC immunologic barrier and prime therapeutic response to DLL3-targeted CAR-NK cell therapy. Overall design: A 3D microphysiological immune tumor environment (MITE) system comprises a microvascular network (MVN) composed of human umbilical vein endothelial cells (HUVEC) and human lung fibroblasts (HLF), surrounding MHC-Ilow/neg CORL47 SCLC (for 6 days). Human NK cells were perfused through the vasculature either without or with human monocytes, without or with the endogenous STING ligand, 2'3'-cGAMP (day 7, endpoint). Next, we developed a dynamic scRNAseq of the MITE (DynaMITE-seq) to investigate the phenotypes of the individual components of the MITE, effectively liberating and recovering cells from the extracellular matrix for scRNAseq at 7 days endpoint.  Experimental conditions (control; cGAMP; control + monocyte; and cGAMP + monocyte).