Enhanced antitumor efficacy of combined targeting of adenosine A2B receptor and PD-1 is mediated via multiple effects on different cell populations within tumor microenvironment

BACKGROUND: Immune checkpoint inhibitors (ICIs) have revolutionized the treatment of non-small cell lung cancer (NSCLC). However, their low response rates and poor 5-year survivals indicate a need for improvement. One key factor in this resistance may be molecules that mediate immunosuppression within the tumor microenvironment (TME), such as adenosine. Combining therapies that mitigate the effects of adenosine with ICIs could potentially overcome these limitations. METHODS: We utilized the Lewis lung carcinoma (LLC) and CMT167 murine lung carcinoma models to investigate the combined use of the A2B receptor antagonist PBF1129 and anti-PD-1 ICI. The mechanisms underlying the efficacy of this combination therapy were explored using single-cell RNA sequencing (scRNA-seq). RESULTS: In both models, combination therapy improved tumor control. Our scRNA-seq analysis characterized alterations in malignant cells, macrophages, cancer-associated fibroblasts (CAFs), T cells, and endothelial cells in the tumor after treatment. Malignant cells treated with combination therapy exhibited reduced inflammatory, epithelial-to-mesenchymal transition (EMT) and angiogenic signatures. Malignant cells and M2-like macrophages showed high expression of TGFβ pathway genes, which were significantly reduced in the combination therapy group. We also observed decreased interactions between M2-like macrophages and CAFs as well as T cells, and dramatically increased Gzmb expression in M1-like macrophages with combination therapy. Combination therapy modulated TGFβ-mediated cellular crosstalk and extracellular matrix (ECM) remodeling. CONCLUSIONS: Our findings suggest that inhibition of adenosine activity by blocking the A2B receptor reduces TGFβ signaling and enhances the efficacy of ICI therapy in NSCLC.