Optimizing virtual hits of human CGAS inhibitors to treat neurodegeneration

摘要 埃顿治疗公司正在开发模式识别受体cGAS(环状GMP-AMP合成酶)的抑制剂 激活刺痛并导致干扰素(β)的产生，作为治疗糖尿病的新疗法 阿尔茨海默病(AD)。AD是最常见的迟发性痴呆症，影响着近5000万人 全世界的人和估计有570万美国人。2020年，医疗保健总支出，长期 为65岁及以上痴呆症患者提供的护理和临终关怀服务估计为3050亿美元。这个 阿尔茨海默病患者认知功能减退与淀粉样蛋白β(Aβ)斑块和神经纤维的形成相关 在大脑中由过度磷酸化的tau组成的缠结。埃顿治疗公司寻求生产一种新的 通过开发cGAS抑制剂(CGASi)治疗AD。CGAS是一种胞质DNA传感蛋白，具有 与许多神经退行性疾病和炎症性疾病有关。在检测到胞浆中的DNA时 (由于病原体的存在、基因组/线粒体损伤或其他病理机制)，cGAS 催化ATP/GTP偶联生成2‘3’-cGAMP，这是一种强有力的STING配体，从而导致 干扰素-β。先前的研究表明，cGAS在后遗症小鼠模型中被异常激活，导致 干扰素反应与神经毒性慢性神经炎。相比之下，在PS19小鼠中，cGAS的遗传消融， 过度表达P301S突变tau并发展tau病理和认知缺陷，保护 认知缺陷和海马区突触丢失。这些发现有力地支持了 CGASi‘s可保护cGAS刺激性过度激活的负面影响，但现有化合物显示 仅适度抑制人THP1髓系细胞中的cGAS-STING通路。发展小说 CGASi‘s用于治疗tau介导的AD神经变性，在这个第一阶段项目中，Aeton Treateutics建议 目的：1.通过有效的HIT1和2的药物化学开发有效的h-cGASi。 已经通过虚拟屏幕确定了有希望的热门歌曲。我们将对h-进行优化和体外评估。 用来确定主要候选人的类比。目的2.测定h-cGASi在体内的PK、靶向性和有效性 人IPSC来源的小胶质细胞和类器官模型。显示大脑高度暴露的两条最佳线索将是 在野生型小鼠的PK研究中进行了评估，并在人类IPSC来源的小胶质细胞和器质中进行了评估。铅 H-cGASi必须减少关键的生物标志物，如CXCL4、Ifnb和TBK1/pTBK1。我们预计至少会确定 一种可以降低细胞和有机物中关键生物标记物的h-cGASi引线，是大脑渗透性的，对 老鼠，不会有偏离目标的效果。这将导致开发新的cGASi，很可能 对有毒的小胶质细胞反应进行重新编程，防止tau相关的认知功能下降。

Abstract Aeton Therapeutics is developing inhibitors of cGAS (cyclic GMP-AMP synthase)—a pattern recognition receptor that activates STING and results in the production of interferon (IFN)-β—as novel therapies for the treatment of Alzheimer’s disease (AD). AD is the most common form of late-onset dementia and affects nearly 50 million people worldwide and an estimated 5.7 million Americans. In 2020, total payments for healthcare, long‐term care, and hospice services for people aged 65 and older with dementia were estimated to be $305 billion. The cognitive decline associated with AD correlates with the formation of amyloid β (Aβ) plaques and neurofibrillary tangles composed of hyperphosphorylated tau in the brain. Aeton Therapeutics seeks to produce a novel therapeutic for AD by developing cGAS inhibitors (cGASi’s). cGAS is a cytosolic DNA sensing protein that has been linked to a number of neurodegenerative and inflammatory diseases. Upon sensing DNA in the cytosol (due to the presence of pathogens, genomic/mitochondrial damage, or other pathological mechanisms), cGAS catalyzes ATP/GTP coupling to produce 2’3’-cGAMP, a potent ligand of STING, resulting in the production of IFN-β. Previous studies suggest that cGAS is aberrantly activated in a tauopathy mouse model, resulting in an IFN response and neurotoxic chronic neuroinflammation. In contrast, genetic ablation of cGAS in PS19 mice, which overexpress P301S mutant tau and develop tau pathology and cognitive deficits, protects against those cognitive deficits and the loss of hippocampal synapses. These findings strongly support the development of cGASi’s to protect against the negative effects of cGAS-STING hyperactivation, but existing compounds exhibit only modest potency in inhibiting the cGAS-STING pathway in human THP1 myeloid cells. To develop novel cGASi’s to treat tau-mediated neurodegeneration in AD, in this Phase I project, Aeton Therapeutics proposes the following aims: Aim 1. Develop potent h-cGASi’s via medicinal chemistry of virtual hits 1 and 2. We have identified promising hits via a virtual screen. We will perform optimization and in vitro assessment of h- analogs to identify lead candidates. Aim 2. Determine PK, target engagement, and efficacy of h-cGASi’s in human iPSC-derived microglia and organoid model. The two best leads showing high brain exposure will be assessed in PK studies in wild-type mice and evaluated in human iPSC-derived microglia and organoids. Lead h-cGASi’s must reduce key biomarkers, such as Cxcl4, Ifnb, and TBK1/pTBK1. We expect to identify at least one lead h-cGASi that reduces key biomarkers in cells and organoids, is brain permeable, shows no toxicity in mice, and does not have off-target effects. This will lead to development of novel cGASi’s that are likely to reprogram toxic microglial responses and protect against tau-related cognitive decline.