Reversal of Tau Pathology with MSUT2 siRNA Conjugates

项目摘要 遗传学和病理学证据表明，进行性核上性麻痹(PSP)是一种“单纯的”自发性疾病。 皮质基底膜变性(CBD)和某些额颞性痴呆(FTD)直接与tau有关 AS导致神经细胞死亡，而在阿尔茨海默病(AD)中，tau的积累与发育相关 和认知障碍的进展。由于(到目前为止)针对淀粉样β蛋白的药物失败，tau已经 现在，在寻找疾病修饰药物的过程中，它已成为“下一个最好的”治疗目标。目前有 在AD和PSP中使用抗tau抗体的2个活跃的2期临床研究正在进行中，另外还有tau抗体 目标特工正在开发中。在这里，我们提出了一种新颖的替代策略来改善神经元tau。 以MSUT2基因表达为靶点的毒性。支持这种方法的知识体系包括 在表达病理基因的转基因动物中剔除MSUT2后体内tau毒性的改善 在体外，敲除MSUT2的siRNA具有细胞保护作用。有效的体内递送 SiRNA结合，较低的MSUT2水平将提供一种独特的手段，以干预与 有一条可行的发展人类治疗方法的途径的优势。我们假设 SiRNA介导的MSUT2水平的降低将在体内保护并可能逆转 由tau蓄积引起的神经退行性变。DTX Pharma创造了一种新的、专有的脂肪酸主题 在体内将siRNA传递到包括中枢神经系统神经元在内的多个细胞/组织中，从而实现有效的靶基因 击倒对手。在这里，我们概述了与Brian Kraemer合作的药物发现计划的初始步骤 使用DTX基序将MSUT2特异性siRNA递送到体内的神经元，以测试MSUT2的敲除是否 Tau介导的变性小鼠模型的神经保护作用。如果成功，这种方法 将先进地产生铅、脂肪酸修饰的MSUT2 siRNA，用于潜在的治疗应用 紧张症。我们提出了3个特定的目标：SA1、MSUT2 siRNAs的产生和筛选 MSUT2表达细胞的活性。最活跃的siRNA与DTX脂肪酸基序的偶联 细胞系和原代神经元中基因敲除效率的评估。SA2，体内实验优化 DTX偶联MSUT2 siRNA的剂量、活性持续时间和潜在毒性评估 野生型老鼠。SA2中发现的一种高效、安全、有效的siRNA SA3将用于治疗突变的tau 在治疗性试验中表达小鼠(PS19)。分析将包括对记忆功能的测量， 磷酸化tau的积聚、聚集性/寡聚体tau的沉积、神经炎症和 神经原纤维变性。我们将比较siRNA介导的MSUT2基因敲除对tau病理的影响 与先前在使用抗tau抗体(C2N/Abbvie)和tau靶向反义的相同小鼠模型中的结果相同 支持目前处于第二阶段的新疗法进展的寡核苷酸(离子/生物遗传) 临床试验。如果我们有类似或更好的活性-我们将寻求推进领先的MSUT2靶向siRNA。

Project Summary Genetic and pathologic evidence in 'pure' tauopathies such as Progressive Supranuclear Palsy (PSP), Corticobasilar Degeneration (CBD) and some cases of Fronto-temporal Dementia (FTD) directly implicate tau as causing neuronal cell death, while in Alzheimer’s Disease (AD) tau accumulation correlates with development and progression of cognitive impairment. Because of failure (to date) of drugs targeting amyloid beta, tau has now emerged as 'the next best' therapeutic target in the search for disease modifying drugs. There are currently 2 active phase 2 clinical studies using anti-tau antibodies in both AD and PSP underway, with additional tau targeting agents under development. Here, we propose a novel, alternative strategy to ameliorate neuronal tau toxicity by targeting MSUT2 gene expression. The body of knowledge supporting this approach includes amelioration of tau toxicity in vivo when MSUT2 is knocked out in transgenic animals expressing a pathologic tau species and in vitro where siRNA's that knock down MSUT2 are cytoprotective. Effective in vivo delivery of siRNA conjugates that lower MSUT2 levels will provide a distinct means of intervening against tauopathy with the advantage of having a viable pathway forward for development of a human therapeutic. We hypothesize that siRNA-mediated reduction of MSUT2 levels will protect against and potentially reverse in vivo neurodegeneration driven by tau accumulation. DTx Pharma has created a novel, proprietary fatty acid motif that delivers siRNA in vivo into multiple cells/tissues, including CNS neurons, allowing efficient target gene knockdown. Here we outline the initial steps of a collaborative drug discovery program with Brian Kraemer that uses the DTx motif to deliver MSUT2 specific siRNA to neurons in vivo to test whether knockdown of MSUT2 is neuro-protective in a well-characterized mouse model of tau-mediated degeneration. If successful, this approach would be advanced to generate lead, fatty acid-modified, MSUT2 siRNAs for potential therapeutic application in tauopathies. We propose 3 specific aims: SA1, generation and screening of MSUT2 siRNAs for gene knockdown activity in MSUT2 expressing cells. Conjugation of the most active siRNAs to the DTx fatty acid motif for evaluation of knockdown efficiency in cell lines and primary neurons. SA2, in vivo experiments to optimize dosing, evaluate duration of activity and assess for potential toxicities of DTx-conjugated MSUT2 siRNAs in wildtype mice. SA3, a potent, safe and efficacious siRNA identified in SA2 will be used to treat mutant tau expressing mice (PS19) in a therapeutic trial. Analyses will include the measurement of memory function, accumulation of phosphorylated tau, deposition of aggregated/oligomeric tau, neuroinflammation, and neurofibrillary degeneration. We will compare the effect of siRNA mediated MSUT2 knockdown on tau pathology with prior results in the same mouse model using anti-tau antibodies (C2N/Abbvie) and tau-targeted antisense oligonucleotides (Ionis/Biogen) that supported advancement of novel therapeutics that are currently in phase 2 clinical trials. If we have similar or better activity—we will seek to advance a lead MSUT2 targeted siRNA.