Ligand discovery for delineating cholesterol homeostasis in the brain

描绘大脑胆固醇稳态的配体发现

• 批准号: 10605057
• 负责人: Steven H Liang
• 金额: $ 77.48万
• 依托单位: EMORY UNIVERSITY
• 依托单位国家: 美国
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-01-01 至 2025-12-31
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/10605057
• 关键词: ABCB1 gene; Affinity; Alzheimer' s Disease; Alzheimer' s disease brain; Alzheimer' s disease therapeutic; Amyloid beta-Protein; Autopsy; Autoradiography; Binding; Biochemical Process; Biodistribution; Biological; Biological Assay; Biological Process; Blood specimen; Brain; Carbon Dioxide; Cerebellum; Cessation of life; Characteristics; Chemistry; Cholesterol; Cholesterol Homeostasis; Clinical; Corpus striatum structure; Deposition; Development; Disease; Disease Progression; Docking; Dose; Evaluation; Functional disorder; Goals; Human; Huntington Disease; Hydroxycholesterols; Image; Imaging Device; In Vitro; Kinetics; Label; Lead; Length; Libraries; Ligands; Mediating; Messenger RNA; Modeling; Molecular; Monitor; Neurodegenerative Disorders; Neurofibrillary Tangles; Penetration; Permeability; Pharmaceutical Chemistry; Pharmaceutical Preparations; Positioning Attribute; Positron-Emission Tomography; Protein Isoforms; Radioactivity; Radiolabeled; Research; Rodent; Schizophrenia; Site; Specificity; Standardization; Testing; Therapeutic; Transgenic Organisms; Translations; United States; Validation; Work; antagonist; brain tissue; cholesterol 24-hydroxylase; clinical translation; design; drug discovery; image translation; imaging study; improved; in vitro Assay; in vivo; in vivo evaluation; knockout gene; mouse model; nervous system disorder; next generation; nonhuman primate; novel; pharmacologic; prototype; radioligand; response; sample fixation; uptake

Alzheimer’s disease (AD) is a long-term neurodegenerative disorder that ranks sixth in the leading cause of all deaths in the United States and features amyloid β protein deposition and neurofibrillary tangles. At present, there are no drugs available to halt or reverse disease progression, and all efforts to create such therapies have failed. Recent studies have demonstrated that abnormalities of cholesterol homeostasis in the brain are strongly associated with several neurodegenerative diseases, including AD. The CYP46A1 enzymatic conversion of brain cholesterol into 24S-hydroxycholesterol is the major elimination mechanism to maintain brain cholesterol homeostasis. Disturbances in CYP46A1 is implicated in the AD physiopathology. Therefore, pharmacological modulation of CYP46A1 represents an attractive AD therapeutic approach. Positron emission tomography (PET) is capable of quantifying biochemical processes in vivo, and a suitable CYP46A1 ligand would substantially improve our understanding of CYP46A1-mediated cholesterol homeostasis under AD physiopathological conditions otherwise inaccessible by ex vivo (destructive) analysis. Quantification of CYP46A1 in living AD brain by PET would provide the assessment of distribution, target engagement and dose occupancy of new AD therapeutics. To date, no successful examples have been demonstrated to image CYP46A1 for clinical use, representing a significant deficiency of our ability to study this target in vivo. Therefore, we propose to develop a novel PET ligand that can fill this void, as the first translational imaging tool for AD. Our ligand [11C]CYP-507 demonstrated the first prototype for imaging towards CYP46A1, but was discontinued due to marginal binding specificity and low brain penetration. In our next generation, we successfully identified a lead molecule, CYP-812, which showed high binding affinity and high selectivity. An 11C-isotopologue of CYP-812 was synthesized and preliminary PET studies confirmed that we have overcome the major obstacles for CYP46A1 ligand development by achieving: 1) reasonable and regional-specific brain uptake; 2) moderate target specificity. Though CYP-812 is a promising lead, further optimizations aimed at higher brain permeability, improved potency and binding specificity with proper brain kinetics are sought for translational cross-species (rodents and nonhuman primates) imaging studies to achieve optimal CYP46A1 quantification for AD research. As specific goals, we will design and prepare a focused library of CYP46A1 modulators amenable for labeling with 11C or 18F, and evaluate their ability to quantify CYP46A1 activity and changes during drug challenge in rodents and nonhuman primates, as well as autoradiography and biological validation in postmortem human brain tissues. The impact of this work is not only to develop the first potent and selective CYP46A1 PET ligand for the study of AD-related biological processes, but also ultimately, via PET imaging validation in higher species, to advance this ligand for potential clinical translation and monitor target response of novel AD neurotherapeutics.

阿尔茨海默氏病（AD）是一种长期神经退行性疾病，在美国所有死亡的主要原因中排名第六，并具有淀粉样蛋白β蛋白质的沉积和神经纤维纤维缠结。目前，尚无停止或反向疾病进展的药物，创建此类疗法的所有努力都失败了。最近的研究表明，大脑中胆固醇稳态异常与包括AD在内的几种神经退行性疾病密切相关。 CYP46A1脑胆固醇酶促转化为24S-羟基胆固醇是维持脑胆固醇稳态的主要进化机制。 AD生理病理学中暗示了CYP46A1中的干扰。因此，CYP46A1的药物调节代表了一种有吸引力的AD治疗方法。正电子发射断层扫描（PET）能够在体内量化生化过程，而合适的CYP46A1配体可以大大提高我们对AD生理病理学条件下的CYP46A1介导的胆固醇稳态的理解，否则否则，否则，否则，Ex Vivo（destructive）分析无法获得。 PET对活广告大脑中CYP46A1的量化将评估分布，目标参与和新AD疗法的占用率。迄今为止，尚未证明成功的例子以形象CYP46A1进行临床使用，这代表了我们在体内研究该靶标的能力的严重缺陷。因此，我们建议开发一种可以填充该空隙的新型宠物配体，作为AD的第一个翻译成像工具。 我们的配体[11C] CYP-507展示了第一个用于对CYP46A1进行成像的原型，但由于边缘结合特异性和脑穿透低而停产。在下一代中，我们成功地鉴定了一个铅分子CYP-812，该分子表现出高结合亲和力和高选择性。合成了CYP-812的11C - 异位学，并初步研究证实，我们通过实现：1）合理和区域特异性的脑吸收来克服CYP46A1配体开发的主要障碍； 2）中等目标特异性。尽管CYP-812是一个承诺的潜在客户，但采用了旨在更高的大脑渗透性，提高效力和与适当脑动力学的结合特异性的进一步优化，以实现转化跨物种（啮齿动物和非人类素质）成像研究，以实现最佳的AD研究CYP46A1量化。作为具体目标，我们将设计和准备一个专注的CYP46A1调节器库，可用于标记11C或18F的标签，并评估其在啮齿动物和非人类隐私的药物挑战期间量化CYP46A1活性和变化的能力，以及在术后人类脑组织中的自显影和生物验证。这项工作的影响不仅是为了研究与AD相关的生物学过程的研究，还可以开发第一个潜力和选择性的CYP46A1 PET配体，而且最终通过较高物种的PET成像验证，以推动这种潜在的临床翻译和监测新型AD神经治疗剂的目标反应。