Vascular STING activation facilitates NK cell anti-tumor immunity in small cell lung cancer.

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 the quantitative spatial profiling of the SCLC immune microenvironment in patient samples reveals that effector immune cells, including NK cells, are excluded from MHC-I(low/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 the 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.