Targeting ApoE4 as a Therapeutic Strategy for Alzheimer's Disease

描述（由申请人提供）：载脂蛋白（apo）E4是阿尔茨海默病（AD）的主要遗传危险因素，apoE 4携带者占AD病例的65-80%。ApoE 4增加了AD的发生率并降低了AD的发病年龄，大量证据表明它在AD的神经退行性变和病理生理学中具有基础性作用。我们发现，apoE 4，因为其独特的结构特征被称为apoE 4结构域相互作用，是高度敏感的神经元蛋白水解裂解，产生神经毒性片段。主要毒性片段apoE 4（1-272）在AD患者的脑和脑脊液中的水平比非痴呆个体和在神经元中表达人apoE 4的转基因小鼠中高得多。这些转基因小鼠有学习和记忆障碍和神经病理学，包括突触树突连接的丧失，这与学习缺陷的发生有关。由apoE 4和apoE 4（1-272）诱导的毒性通过其对线粒体功能的抑制介导，线粒体功能是导致AD中神经变性和认知障碍的初始事件。因此，许多研究已经证实apoE 4是AD药物的极好靶点。我们发现了结合apoE 4的小分子来修饰蛋白质的结构，以减少结构域相互作用和蛋白水解切割，从而防止其毒性。我们的主要apoE 4结构校正剂（apoE 4SC），PY-101，保护神经元免受apoE 4诱导的线粒体毒性，并逆转体外神经突生长的损伤。在体内，PY-101具有良好的药代动力学（PK）和脑生物利用度，阻断神经元特异性烯醇化酶（NSE）-apoE 4转基因小鼠脑中毒性apoE 4（1-272）的形成，并保护脑中线粒体损伤，这是AD疾病进展的初始事件。在U 01资助中，我们计划开展临床前研究，以评估PY-101作为治疗AD的独特药物的疗效。我们将在AD的NSE-apoE 4和APP/apoE 4动物模型中测试PY-101阻断认知障碍和神经病理学的功效，以验证PY-101作为治疗AD的药物。此外，我们将专注于使用基于PY-101的结构-活性关系的药效团模型优化apoE 4SCs的性质。我们将使用该模型围绕新的化学系列构建化学优化程序，以提高我们的原型apoE 4SC的效力，同时保持良好的PK和高脑渗透性。使用模型，药物化学和我们的高通量筛选试验，我们将优化我们的apoE 4SCs的功效和药物特性。为此，将针对我们的主要GFP-apoE 4-eDHFR FRET测定筛选小分子，该测定测量靶结合和破坏apoE 4结构域相互作用以增加apoE 4稳定性的能力。优化的apoE 4SC将进行稳定性、PK和药效学研究，以选择用于测试AD小鼠模型中的功效的先导物。主要的apoE 4SC将接受标准的研究性新药临床前开发，目的是启动临床研究，以测试治疗D的安全性和有效性，并进入IND。 公共卫生相关性：阿尔茨海默病是一种毁灭性的神经退行性疾病，在美国影响着500多万人，每年花费医疗保健社区1720亿美元。我们建议鉴定靶向载脂蛋白E4的新型小分子，这些小分子旨在中和这种蛋白质及其片段对线粒体的毒性，以防止神经变性和阿尔茨海默病的进展。在这些研究中发现的有效化合物将在临床前研究中开发，目的是在人类中测试选定的临床候选物在治疗阿尔茨海默病中的安全性和有效性。

DESCRIPTION (provided by applicant): Apolipoprotein (apo) E4 is the major genetic risk factor for Alzheimer's disease (AD), and apoE4 carriers account for 65-80% of AD cases. ApoE4 increases the occurrence and lowers the age of onset of AD, and considerable evidence suggests that it has a fundamental role in the neurodegeneration and pathophysiology of AD. We showed that apoE4, because of its unique structural feature referred to as apoE4 domain interaction, is highly susceptible to proteolytic cleavage in neurons, generating neurotoxic fragments. The primary toxic fragment, apoE4(1-272), is found at much higher levels in the brain and cerebrospinal fluid of AD patients than non-demented individuals and in transgenic mice expressing human apoE4 in neurons. These transgenic mice have learning and memory impairments and neuropathology, including loss of synaptodendritic connections, which correlates with the onset of learning deficits. The toxicity induced by apoE4 and apoE4(1-272) is mediated by their inhibition of mitochondrial function, an initial event leading to neurodegeneration and cognitive impairment in AD. Thus, a number of studies have validated apoE4 as an excellent target for AD drugs. We discovered small molecules that bind apoE4 to modify the protein's structure to reduce domain interaction and proteolytic cleavage to prevent its toxicity. Our lead apoE4 structure corrector (apoE4SC), PY-101, protects neurons from apoE4-induced mitochondrial toxicity and reverses the impairment of neurite outgrowth in vitro. In vivo, PY-101 has good pharmacokinetics (PK) and brain bioavailability, blocks formation of toxic apoE4(1-272) in neuron-specific enolase (NSE)-apoE4 transgenic mouse brain, and protects against mitochondrial impairment in brain, an initial event in disease progression in AD. In this U01 grant, we propose to conduct the preclinical studies to evaluate the efficacy of PY-101 as a unique drug to treat AD. We will test PY-101 for efficacy in blocking cognitive impairment and neuropathology in the NSE-apoE4 and APP/apoE4 animal models of AD to validate PY-101 as a drug to treat AD. In addition, we will focus on optimizing the properties of apoE4SCs using our pharmacophore model based on the structure-activity relationship around PY-101. We will use this model to build a chemical optimization program around a novel chemical series to improve the potency of our prototypical apoE4SC while maintaining good PK and high brain penetration. Using the model, medicinal chemistry, and our high-throughput screening assays, we will optimize the efficacy and pharmaceutical properties of our apoE4SCs. To do this, small molecules will be screened against our primary GFP-apoE4-eDHFR FRET assay, which measures target engagement and the ability to disrupt apoE4 domain interaction to increase apoE4 stability. Optimized apoE4SCs will be subjected to stability, PK, and pharmacodynamic studies to select leads to test for efficacy in AD mouse models. The lead apoE4SC will be subjected to standard investigational new drug-enabling preclinical development with a goal of initiating clinical studies to test for safety and efficacy in treating D and proceeding to an IND. PUBLIC HEALTH RELEVANCE: Alzheimer's disease is a devastating neurodegenerative disease that affects more than 5 million people in the U.S., and costs the healthcare community $172 billion annually. We propose to identify novel small molecules targeting apolipoprotein E4 that are designed to neutralize the toxicity this protein and its fragments exert on mitochondria to prevent neurodegeneration and progression of Alzheimer's disease. Effective compounds discovered in these studies will be developed in preclinical studies with the goal of testing a selected clinical candidate in humans for safety and efficacy in treating Alzheimer's disease.