CD73 inhibitor AB680 suppresses glioblastoma in mice by inhibiting purine metabolism and promoting P2RY12+ microglia transformation
CD73 is the metabolic immune checkpoint that dephosphorylates AMP to produce adenosine, adenosine plays a pivotal role in immunosuppressive tumor microenvironment (TME) through adenosine receptors expressed in different immune cells. AB680, a specific CD73 inhibitor, is currently undergoing clinical trials for highly refractory cancers. In this study we investigated the antitumor effects and mechanisms of AB680 on glioblastoma (GBM). By analyzing the expression pattern of CD73 in all cell types in orthotopic G422TN-GBM tumors (d 7), we found that CD73 were significantly elevated in G422TN-GBM cells compared to all other cell types. High CD73 expression was also found in human GBM samples that was correlated to shorter patient survival. Administration of AB680 significantly prolonged survival in G422TN-GBM-bearing mice, reduced tumor size/cell proliferation/angiogenesis, and boosted microglia activation and anti-tumor immune responses. Metabolomic analysis revealed that AB680 markedly increased ADP and AMP levels in the TME of orthotopic G422TN-GBM, thereby stimulating P2RY12+ microglia activation to exert their M1-like anti-cancer functions that were confirmed by human GBM scRNA-seq and G422TN-GBM snRNA-seq results. Furthermore, AB680 combined with RT/TMZ exhibited synergistic therapeutic effects by reversing RT/TMZ-enhanced adenosine levels, as well as promoting P2RY12+ microglia transformation. Overall, this study demonstrates that targeting CD73 with AB680 alters purine metabolism in GBM microenvironment, promotes the transformation of P2RY12+ microglia, and triggers robust anti-tumor immune responses. These results support the rationale for AB680-based therapeutic clinical trials for GBM.