Anti-tumor efficacy of novel cGAS-STING pathway agonists

项目摘要 该提案的目标是对激活先天性免疫缺陷的新型化合物进行分子和免疫学检查。 由蛋白质环GMP-AMP（cGAMP）合酶（cGAS）和免疫刺激因子介导的免疫信号传导 干扰素基因（STING）。先天免疫在模式识别受体参与后启动， 指示微生物感染或垂死细胞的分子。这些导致了适应性免疫的协调， 随后消除癌变或感染组织的反应。cGAMP是主要的活化配体， STING及其合成由CGAS和胞质DNA之间的接触触发。巨噬细胞、树突状细胞 (DCs)内皮细胞在吞噬凋亡细胞的物质后暴露于胞质DNA 包括肿瘤微环境中的那些。STING介导的信号传导导致I型干扰素的分泌 IFN-1和促炎细胞因子，然后激活抗原呈递细胞（APC），从而促进免疫应答。 抗原导向的T细胞杀伤。事实上，STING是启动免疫反应所必需的， 肿瘤细胞有趣的是，STING依赖性过程的药理学激活可导致自发性 肿瘤清除和甚至肿瘤抗原衍生的保护性免疫。许多努力是 因此，重点是了解STING介导的治疗性免疫缺陷的分子和免疫学基础， 结果，以及确定新的分子实体，可以安全地引发这些。我们的工作已经确定了六个 诱导cGAS介导的cGAMP合成而不影响胞质DNA水平的小分子类似物。 这些直接激活人和鼠细胞中的STING依赖性表型。此外，瘤内 在小鼠癌症模型中施用原始母体分子导致肿瘤生长受损， 延长动物生存期。我们假设，我们改进的类似物，当与优化的配方配对时， 对于体内使用，将表现出增强的抗肿瘤活性。据我们所知，这些代表了第一个合成的直接 cGAS介导的信号传导的诱导剂。因此，它们在建立cGAS方面具有独特的地位 (and可能是一般的STING调节蛋白）作为可行的药物靶点，也揭示了新的见解， cGAS-STING在抗肿瘤免疫中的作用。因此，我们建议进行一个深入和比较 免疫学和分子反应、抗肿瘤能力和潜在不良反应的表征 本发明的新型cGAS激动剂制剂在癌症的鼠模型中的作用。结果将允许一个机械的 评估其免疫效用，特别是与临床研究相比 分子和涉及与检查点抑制剂组合的疗法。我们历史上的合作小组 拥有先天免疫、分子生物学、T细胞免疫学和癌症免疫治疗方面的专业知识， 因此，我们有能力进行这些研究。

PROJECT SUMMARY The goal of this proposal is a molecular and immunological examination of novel compounds that activate innate immune signaling mediated by the proteins cyclic GMP-AMP (cGAMP) synthase (cGAS) and Stimulator of Interferon Genes (STING). Innate immunity is initiated following engagement of pattern recognition receptors by molecules indicative of microbial infection or dying cells. These lead to the orchestration of adaptive immune responses that subsequently eliminate cancerous or infected tissues. cGAMP is the primary activating ligand of STING and its synthesis is triggered by contact between cGAS and cytosolic DNA. Macrophages, dendritic cells (DCs), and endothelial cells are exposed to cytosolic DNA following phagocytosis of material from apoptotic cells including those in the tumor microenvironment. STING-mediated signaling leads to secretion of type I interferons (IFN-I) and proinflammatory cytokines that then activate antigen-presenting cells (APCs), thereby facilitating antigen-directed T-cell killing. STING is, in fact, required for initiating immune responses capable of clearing tumor cells. Intriguingly, pharmacologic activation of STING-dependent processes can lead to spontaneous tumor clearance and even tumor antigen-derived protective immunity in murine models. Numerous efforts are thus focused on understanding the molecular and immunological bases of STING-mediated therapeutic outcomes as well as identifying new molecular entities that can safely elicit these. Our work has identified six small molecular analogs that induce cGAS-mediated synthesis of cGAMP without affecting cytosolic DNA levels. These directly activate STING-dependent phenotypes in both human and murine cells. Moreover, intratumoral administration of the original parent molecule in mouse models of cancer led to impaired tumor growth and prolonged animal survival. We hypothesize that our improved analogs, when paired with formulations optimized for in vivo use, will exhibit enhanced antitumor activity. To our knowledge these represent the first synthetic direct inducers of cGAS-mediated signaling yet described. As such, they are uniquely positioned to establish cGAS (and perhaps STING regulatory proteins in general) as a viable drug target and also reveal new insights into the role of cGAS-STING in antitumor immunity. We thus propose to undertake a penetrative and comparative characterization of the immunological and molecular responses, anti-tumor capacities, and potential adverse effects of our novel cGAS agonist formulations in murine models of cancer. Results will allow a mechanistic assessment to be made of their immunotherapeutic utility, especially in comparison to clinically pursued molecules and in therapies involving combination with checkpoint inhibitors. Our historically collaborative group possesses expertise in innate immunity, molecular biology, T cell immunology, and cancer immunotherapy and is thus well positioned to execute these studies.