放疗通过c-GAS/Sting通路诱导OX40在PD-L1低表达肺癌中免疫激活效应的机制研究

Non-small cell lung cancer patients with low expression of PD-L1 were insensitive to the current routine therapy and had poor prognosis. Most of the patients showed tumor regression and increased the expression of ox40 on T cells after high dose radiotherapy. In the mice lung cancer model treated with radiotherapy and ox40 agonist, it was found that the number of infiltrating lymphocytes and M1 macrophages increased significantly, and the innate immune cgas/sting pathway was both activated. We speculate that radiotherapy may activate the cgas/sting and ox40/ox40l pathways and enhance the systemic anti-tumor immune response through network interaction. This application based on the previous studies is intended to elucidate the specific mechanism of cgas/sting pathway in ox40/ox40l immune activation effect and the regulatory mechanism of polarized macrophages on the expression of ox40 in tumor infiltrating CD4+T lymphocytes at the animal and cell levels. Meanwhile, the dynamic changes of tumor and immune environment after radiotherapy combined with ox40 agonist were observed in order to find a new therapeutic target for this type of lung cancer patients.

PD-L1低表达的非小细胞肺癌患者对当前临床常规治疗手段皆不敏感且预后差，申请者前期临床发现，PD-L1低表达的大部分患者在高剂量放射治疗后出现肿瘤消退现象且其T细胞OX40表达增加；同时，应用放疗联合OX40激动剂的小鼠肺癌模型中发现瘤内浸润淋巴细胞和M1型巨噬细胞数量明显增多，且小鼠体内固有免疫cGAS/Sting通路被激活。由此，我们推测放疗可能激活了cGAS/STING和 OX40/OX40L通路，并通过网络互作共同增强机体全身抗肿瘤免疫反应。本申请拟在前期基础上，在动物和细胞层面上阐明cGAS/STING通路在OX40/OX40L免疫激活效应的具体机制，及其极化巨噬细胞对肿瘤浸润CD4+T淋巴细胞表达OX40的调节机制。同时，动物实验动态观察放疗联合 OX40激动剂处理后肿瘤及其免疫环境不同时间窗变化，以期为此类型肺癌患者找到新的治疗靶点。

c-GAS/STING信号通路在肿瘤细胞中既可产生免疫效应又可使癌细胞凋亡，在肿瘤细胞中由于染色体大量复制，DNA 泄露在细胞质中，加大其与DNA感受器结合的概率，进而激活c-GAS/STING通路，产生抗肿瘤免疫效应；许多证据表明c-GAS/STING激动剂与免疫疗法结合可有效根除肿瘤，诱导持久抗肿瘤免疫反应。与T细胞启动和增殖相关的共刺激受体OX40具有相当的研究价值，而OX40异常表达与PD-L1低表达肺癌发生发展密切相关，但确切机制亟待阐明。本项目首先研究cGAMP联合OX40瘤内注射对荷瘤小鼠的治疗作用；继而从细胞分子水平揭示通过cGAS/STING通路激动剂联合αOX40/CpG的原位疫苗策略克服典型的αPD-1耐药恶性肿瘤的机制；最后开发以CpG/OX40/cGAMP为基石的新型治疗性及预防性全细胞疫苗，为转移性黑色素瘤和其他恶性肿瘤的临床治疗提供了新思路。