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.

CD73是一种代谢性免疫检查点（metabolic immune checkpoint），可将腺苷一磷酸（AMP）去磷酸化生成腺苷。腺苷可通过在不同免疫细胞表面表达的腺苷受体，在免疫抑制性肿瘤微环境（tumor microenvironment, TME）中发挥关键调控作用。AB680作为一种特异性CD73抑制剂，目前正针对高度难治性癌症开展临床试验。本研究探究了AB680对胶质母细胞瘤（glioblastoma, GBM）的抗肿瘤效应及其作用机制。通过分析原位G422TN-GBM移植瘤（接种后第7天）中所有细胞类型的CD73表达模式，我们发现相较于其他所有细胞类型，G422TN-GBM细胞的CD73表达水平显著升高。在人类GBM样本中同样检测到高CD73表达，且该表达与患者更短的总生存期显著相关。给予AB680治疗可显著延长原位G422TN-GBM荷瘤小鼠的生存期，缩小肿瘤体积、抑制肿瘤细胞增殖与血管生成，并增强小胶质细胞活化及抗肿瘤免疫应答。代谢组学分析显示，AB680可显著升高原位G422TN-GBM肿瘤微环境中的二磷酸腺苷（ADP）与AMP水平，进而激活P2RY12+小胶质细胞，使其发挥M1型抗肿瘤功能；该结论通过人类GBM单细胞RNA测序（single-cell RNA sequencing, scRNA-seq）及G422TN-GBM单细胞核RNA测序（single-nucleus RNA sequencing, snRNA-seq）结果得到了验证。此外，AB680与放疗（radiation therapy, RT）/替莫唑胺（temozolomide, TMZ）联合使用可发挥协同治疗效应，其机制包括逆转RT/TMZ诱导的腺苷水平升高，以及促进P2RY12+小胶质细胞的表型转化。综上，本研究证实，通过AB680靶向CD73可改变GBM微环境中的嘌呤代谢，促进P2RY12+小胶质细胞的表型转化，并触发强烈的抗肿瘤免疫应答。上述研究结果为基于AB680的GBM治疗临床试验提供了理论依据。