Remodeling of the tumor microenvironment via blockade of LAIR-1 and TGF-ß signaling [single cell RNA-seq]

Collagens in the extracellular matrix (ECM) provide a physical barrier to tumor immune infiltration, while also acting as a ligand for immune inhibitory receptors. Transforming growth factor-ß (TGF-ß) is a key contributor to shaping the ECM by stimulating the production and remodeling of collagens. TGF-ß-activation signatures and collagen-rich environments have both been associated with T-cell exclusion and lack of responses to immunotherapy. Here we describe the effect of targeting collagens that signal through the LAIR-1 inhibitory receptor in combination with blockade of TGF-ß and programmed cell death ligand 1 (PD-L1). This approach remodeled the tumor collagenous matrix, enhanced tumor infiltration and activation of CD8+ T cells, and repolarized suppressive macrophage populations resulting in high cure rates and long-term tumor-specific protection across murine models of colon and mammary carcinoma. The results highlight the advantage of direct targeting of ECM components in combination with immune checkpoint blockade therapy. Overall design: Analysis of tumor infiltrating immune cells from control or immunotherapy treated tumor bearing mice.