ApoE4-targeted therapeutics that normalize SirT1

 描述（由申请人提供）：我们的研究首次将阿尔茨海默病的主要风险因素-ApoE 4-与主要长寿决定因素Sirtuins联系起来;并确定了针对这种新联系的第一种候选疗法。阿尔茨海默病（AD）目前在美国折磨着超过540万人，估计每年给社会造成的成本超过2000亿美元。目前批准的AD药物仅提供短期症状缓解，但不会改变疾病进展。阿尔茨海默病（AD）的主要危险因素是载脂蛋白E（ApoE 4）的E4 -4（e4）等位基因，约三分之二的AD患者中存在该等位基因。ApoE 4等位基因（染色体位点19 q13）增加了散发性和迟发型AD（LOAD）的风险。尽管十多年来人们已经认识到ApoE 4等位基因在某种程度上对疾病过程有贡献，但ApoE 4相关AD风险的确切分子机制仍不清楚。我们的研究揭示了ApoE 4介导的毒性的一种新机制，并揭示了一种关键介质-SirT 1-受ApoE 4与ApoE 3的不同影响。有趣的是，虽然ApoE 3和ApoE 4都与APP结合，但只有ApoE 4以纳摩尔亲和力结合，（Kd ~ 80 nM），并且只有ApoE 4显著：（a）降低sAPPa与APPa的比率;（B）降低SirT 1表达，导致SirT 1水平和神经保护性SirT 1与神经毒性SirT 2的比率显著降低;（c）触发tau和APP磷酸化;和（d）诱导程序性细胞死亡。在我们对临床图书馆的初步筛选中， 我们已经鉴定了一种有希望的命中物（A03），其是再利用的候选物，是高度脑渗透性的，并且逆转SirT 1水平的降低。作为该提案的一部分，我们计划完成A03的临床前试验，并开发A03的新化学实体（NCE）类似物以进行进一步开发。此外，通过筛选和“点击到铅”优化，我们计划发现新的铅候选人进行进一步的测试。该提案的最终目标是为非GLP毒性试验提供1-2种候选药物。我们的数据支持这一假设，即神经元连接-受关键介质的比例影响，包括sAPPa：ApoA，SirT 2：SirT 1，APP：p-APP和tau：p-tau -被ApoE 4编程改变。与临床中心和Gylys实验室的合作在该项目中非常重要，因为它将提供来自ApoE基因型患者的血浆和CSF样本的SirT 1水平的初步分析。这些数据对于未来开发ApoE 4靶向候选药物进行临床测试以及SirT 1作为MCI/AD的潜在血浆生物标志物非常有用。此外，计划将SirT 1与血浆/CSF中受sirtuin/NFkB信号影响的其他生物标志物进行比较，这将有助于进一步阐明ApoE 4在AD中的作用。该项目的总体主要目标是确定有效的、口服活性的、脑渗透性的SirT 1增强型先导候选药物，这些药物适合作为首个针对AD的ApoE 4靶向SirT 1治疗药物进行进一步的临床前IND开发，并开发确定靶点参与和疗效所需的工具。

 DESCRIPTION (provided by applicant): Our studies link for the first time the major risk factor for Alzheimer's disease - ApoE4 - with major longevity determinants, the Sirtuins; and identify the first candidate therapeutics that target this new link. Alzheimer's disease (AD) currently afflicts more than 5.4 million people in the US at an estimated cost to society of greater than $200 billion per year. The currently approved drugs for AD provide only short-term symptomatic relief but do not alter disease progression. The dominant risk factor for Alzheimer's disease (AD) is the epsilon-4 (e4) allele of apolipoprotein E (ApoE4), which is present in about two-thirds of AD patients. The ApoE4 allele (chromosomal locus 19q13) confers increased risk for sporadic and late-onset AD (LOAD). Despite over a decade of knowledge that the ApoE4 allele is somehow contributory to the disease process, the precise molecular mechanisms underlying ApoE4-associated AD risk remain unclear. Our studies shed light on a novel mechanism for ApoE4-mediated toxicity and revealed a key mediator - SirT1 - that is differentially affected by ApoE4 vs. ApoE3. Interestingly, while both ApoE3 and ApoE4 bind to APP, only ApoE4 associates with nanomolar affinity (Kd ~80nM), and only ApoE4 significantly: (a) reduces the ratio of sAPPa to Aß; (b) reduces SirT1 expression, resulting in a marked reduction of SirT1 levels and in the ratio of neuroprotective SirT1 to neurotoxic SirT2; (c) triggers tau and APP phosphorylation; and (d) induces programmed cell death. In our initial screen of a clinical library we have identified a promising hit (A03) that is a repurposing candidate, is highly brain permeable, and reverses the reduction of SirT1 levels. As part of this proposal we plan to complete the preclinical testing of A03 and develop new chemical entity (NCE) analogs of A03 for further development. In addition, through screening and "hit-to-lead" optimization we plan to discover new lead candidates for further testing. The eventual goal of the proposal is to provide 1-2 candidates for non-GLP toxicity testing. Our data support the hypothesis that neuronal connectivity - influenced by the ratios of critical mediators including sAPPa:Aß, SirT2:SirT1, APP:p-APP, and tau:p-tau - is programmatically altered by ApoE4. The collaboration with the Clinical Core and the Gylys lab is important in this project, as it would provide preliminary analysis of plasma and CSF samples from ApoE genotyped patients for levels of SirT1. Such data would be extremely useful for future development of ApoE4-targeted drug candidates to clinical testing and SirT1 as a potential plasma biomarker in MCI/AD. In addition, comparing SirT1 with other biomarkers in plasma/CSF that are affected by the sirtuin/NFkB signaling is planned and would help further elucidate the role of ApoE4 in AD. The overall primary objective of this project is to identify potent, orally active, brain permeable SirT1-enhancing lead candidates that are suitable for further preclinical IND development as the first ApoE4- targeted SirT1 therapeutics for AD and to development the tools necessary to ascertain target engagement and efficacy.