Remodeling the tumor microenvironment via blockade of LAIR-1 and TGF-β signaling enables PD-L1–mediated tumor eradication

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Abstract

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-β (TGF-β) is a key contributor to shaping the ECM by stimulating the production and remodeling of collagens. TGF-β 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 inhibitory leukocyte-associated immunoglobulin-like receptor-1 (LAIR-1) in combination with blockade of TGF-β 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.

Authors

Lucas A. Horn, Paul L. Chariou, Sofia R. Gameiro, Haiyan Qin, Masafumi Iida, Kristen Fousek, Thomas J. Meyer, Margaret Cam, Dallas Flies, Solomon Langermann, Jeffrey Schlom, Claudia Palena