Design And Development Of Experimental Therapeutics

实验疗法的设计和开发

• 批准号: 6530309
• 负责人: Nigel H. Greig
• 金额: --
• 依托单位: NATIONAL INSTITUTE ON AGING
• 依托单位国家: 美国
• 资助国家: 美国
• 起止时间: 至
• 项目状态: 未结题
• 来源: https://reporter.nih.gov/project-details/6530309
• 关键词: Alzheimer's disease; Parkinson's disease; aging; brain disorder chemotherapy; cardiovascular agents; cardiovascular disorder chemotherapy; cardiovascular pharmacology; drug design /synthesis /production; drug screening /evaluation; endocrine pharmacology; human subject; human therapy evaluation; hypoglycemic agents; neuropharmacologic agent; neuropharmacology; noninsulin dependent diabetes mellitus; patient oriented research; stroke

Design and Development of Drugs and Pharmacologic Probes The goal of the Drug Design & Development Section is to develop novel agents against rate-limiting steps involved in the pathophysiology of diseases associated with aging, with particular interest in neurological diseases, such as Alzheimer's disease (AD) and stroke, as well as in systemic diseases, such as diabetes. Alzheimer's Disease: Although the neuropathological quantification of beta-amyloid (Ab) plaques and neurofibrillary tangles in the AD brain is the basis for confirming disease diagnosis after death, it is the neocortical synapses rather than the plaques and tangles that correlates best to psychometric indices of cognitive performance in AD. The loss of cholinergic synaptic markers in selected brain regions remains one of the earliest events leading to AD, with the cholinergic system being the most affected of the neurotransmitters and intimately involved in memory processing. Anticholinesterases: Our efforts have focused on augmenting the cholinergic system, but maintaining the normal temporal pattern of neurotransmitter release by selectively inhibiting the enzyme acetylcholinesterase (AChE), acetylcholine?s (ACh) degrading enzyme. Extensive studies involving chemistry, X-ray crystallography, biochemistry and pharmacology resulted in the ability to differentiate between the cholinesterase subtypes. This has provided us the ability to develop novel agents to selectively and reversibly inhibit either AChE or butyrylcholinesterase (BChE) in either the brain or periphery for an optimal duration for the potential treatment of a variety of diseases, such as AD, Myasthenia Gravis, and as chemical warfare prophylactics. Acetylcholinesterase: Two of numerous novel synthesized AChE inhibitors are in development for the treatment of AD; specifically, the pure non-competitive inhibitors, phenserine and tolserine. Both are phenylcarbamates of physostigmine that are 70- and 190-fold selective for AChE vs. BChE. Compared to current agents for AD treatment, they have a favorable toxicologic profile and robustly enhances cognition in animal models. Studies were undertaken to determine their time-dependent effects on cholinergic function, AChE activity, brain and plasma drug levels and brain extracellular ACh concentrations in rodents to support clinical studies. They possess along duration of action, coupled with a short pharmacokinetic half-life, reduces dosing frequency, decreases body drug exposure and minimizes the dependence of drug action on the individual variations of drug metabolism commonly found in the elderly In a collaboration with Axonyx Corp. (New York), clinical studies were undertaken to evaluate the safety, maximum tolerated dose (MTD), pharmacokinetics (PK), and pharmacodynamics (PD) of phenserine tartrate, in healthy elderly subjects to support efficacy trials. Specifically, a Phase I, blinded, placebo controlled, dose escalation study, was undertaken in healthy elderly volunteers (n=32) that received single oral doses (5 to 20 mg). In conclusion, phenserine tartrate was safe and well tolerated as a single oral dose of either 5 or 10 mg. Further studies demonstrated safety following twice daily dosing for 5 consecutive days, and the agent is currently in phase II clinical efficacy trials in volunteers with mild to moderate AD. Butyrylcholinesterase: In the normal brain, approximately 80% of brain cholinesterase activity is AChE, 20% is BChE. AChE activity is concentrated mainly in neurons, while BChE is primarily associated with glial cells. Kinetic evidence indicates a role for BChE, in hydrolysing excess ACh. In advanced AD, however, AChE activity decreases to 15% of normal levels in specific brain regions, whereas BChE activity increases. The ratio of BChE to AChE is set in normal brain to achieve optimal brain activity and changes dramatically in cortical regions as AD progresses, thereby changing BChE?s role. Highly potent BChE inhibitors have been synthesized and are in preclinical assessment to evaluate their potential AD drug candidates. Molecular events associated with AD: The reduction in levels of the potentially toxic amyloid-b peptide (Ab) has emerged as an important therapeutic goal in AD. Key targets for this goal are factors that affect the expression and processing of the Ab precursor protein (bAPP). Our earlier research showed that our AChE inhibitor, phenserine, reduces bAPP levels in vivo. We therefore studied the mechanism of phenserine's actions to define the regulatory elements in bAPP processing. Phenserine treatment resulted in decreased secretion of soluble bAPP and Ab in cultured human neuroblastoma cells without toxicity. This activity was unrelated to its action as an anticholinesterase, but was post-transcriptional as it suppressed bAPP protein expression without altering bAPP mRNA levels. This was mediated via 5' untranslated region (5 UTR) of bAPP mRNA. We have synthesized novel agents to both characterize the target as well as to selectively and optimally regulate bAPP mRNA translation to reduce Ab synthesis. Stroke and Parkinson's disease: Drugs currently used in patients with stroke and Parkinson's disease (PD) provide temporary relief of symptoms, but do not prevent the cell death. Cell death in both results from a process called apoptosis, which may be triggered by mitochondrial impairment and oxidative stress. As up-regulation of p53 has been described as a common feature of several neurodegenerative disorders, and is a critical and rate-limiting step in the cascade of biochemical events that leads to apoptosis, it represents a potential target for interventive drug development. As a consequence, we recently designed and synthesized a novel series of tetrahydrobenzothiazole analogues that are based on the structure of the antihelminthic compound, pifithrin-a . Compounds are currently being assessed for neuroprotective action in tissue culture and in animal models to select agents of potential for evaluation as drug candidates. Diabetes: Type 2 diabetes is a prevalent disease in the elderly. It is caused by a relative deficiency of insulin and a decrease in insulin action at insulin-sensitive tissues. Present treatments are less than satisfactory. In collaborative studies with Josephine Egan, M.D. (Diabetes Section, LCS, NIA), we have extensive experience with GLP-1, a peptide that is actively secreted from the gut in response to food and is a potent secretagogue (i.e., insulinotropic), as a potential treatment for diabetes. When given continuously to diabetic subjects, pharmacological concentrations of GLP-1 can maintain blood glucose levels within their normal range. However, a major shortcoming of GLP-1 given exogenously as a potential therapeutic is its brief biological half-life, it is cleared within minutes in both rodents and humans. As a consequence, GLP-1 was used as a starting point to develop longer acting peptides Studies with exendin-4, an endogenous peptide from the Gila monster lizard that shares 53% homology with GLP-1, have shown that it, is (i) more potent and (ii) maintains higher plasma levels of insulin over, (iii), a longer time duration than does GLP-1, and (iv) have supported the development of exedin-4 into phase II efficacy studies for the treatment of type 2 diabetes. Novel, chimeric peptides that combine the best features of GLP-1 and exendin-4 have been design, synthesized and are under assessment in a variety of cell culture and animal models to assess their potential for clinical development.

药物和药理学探测药物设计与开发部分的设计和开发是针对与衰老相关的疾病病理生理学涉及的限制性限制性步骤，对神经系统疾病特别感兴趣，例如阿尔茨海默氏病（AD）和中风（AD）和系统疾病，以及在系统性疾病中以及系统性疾病。阿尔茨海默氏病：尽管AD脑中的β-淀粉样蛋白（AB）斑块和神经原纤维缠结的神经病理学定量是确认死后疾病诊断的基础，但它是新皮质突触的诊断，而不是斑块和​​缠结，而不是与AD的认知性能表现最好的斑块。选定大脑区域中胆碱能突触标记的丧失仍然是导致AD的最早事件之一，胆碱能系统是神经递质中受影响最大的人，并且密切参与记忆处理。抗胆碱酯酶：我们的努力集中在增强胆碱能系统上，但通过选择性抑制乙酰胆碱酯酶（ACHE），乙酰胆碱？S（ACH）降解酶来维持神经递质释放的正常时间模式。涉及化学，X射线晶体学，生物化学和药理学的广泛研究导致区分胆碱酯酶亚型的能力。这为我们提供了开发新型药物的能力，可以选择性地抑制大脑或周围的ACHE或丁酰胆碱酯酶（BCHE），以最佳持续时间，以便对多种疾病的潜在治疗，例如AD，疗程，肌无力，重力疗法，以及作为化学狂热的预言。乙酰胆碱酯酶：众多新型合成的ACHE抑制剂中有两个正在开发AD治疗。具体而言，纯的非竞争性抑制剂，保透明碱和托尔赛因。两者都是Physostigmine的苯基钙化，对于ACHE与BCHE的选择性为70倍和190倍。与当前的AD治疗药物相比，它们具有良好的毒性特征，并且在动物模型中稳健地增强了认知。进行研究以确定其对胆碱能功能，ACHE活性，大脑和血浆药物水平以及啮齿动物中脑外部ACH浓度的时间依赖性影响，以支持临床研究。它们具有行动持续时间，再加上短的药代动力学半衰期，降低了给药频率，减少了人体药物的暴露，并最大程度地减少了药物作用对与Axonyx Corp.（纽约）合作的老年人通常在老年人中常见的药物代谢变化的依赖，临床研究的最大程度可以评估安全性（POK），供应（PK）（PK）（PK），PK）（PK），MT），MTING（MT），MT）在健康的老年受试者中，Phenserine tartrate的药效学（PD）支持疗效试验。具体而言，在健康的老年志愿者（n = 32）中进行了单次口服剂量（5至20 mg）的健康老年志愿者（n = 32）进行了I期，盲目的安慰剂控制，剂量升级研究。总而言之，金酸脂酸盐是安全且耐受性良好的单一口服剂量的5或10 mg。进一步的研究表明，连续5天每天两次给药后安全性，并且该药物目前正在轻度至中度AD的志愿者中进行II期临床疗效试验。丁乙酸酯酶：在正常大脑中，大约80％的脑胆碱酯酶活性是疼痛，20％是BCHE。 ACHE活性主要集中在神经元中，而BCHE主要与神经胶质细胞有关。动力学证据表明BCHE在水解过量ACH中的作用。然而，在晚期AD中，在特定大脑区域中，ACHE活性降至正常水平的15％，而BCHE活性增加。 BCHE与ACHE的比率在正常的大脑中设定为达到最佳的大脑活动，并随着AD的进展而在皮质区域发生巨大变化，从而改变了BCHE的作用。高度有效的BCHE抑制剂已经合成，并且正在临床前评估以评估其潜在的AD候选药物。与AD相关的分子事件：潜在毒性淀粉样蛋白-B肽（AB）水平的降低已成为AD中重要的治疗目标。该目标的主要目标是影响AB前体蛋白（BAPP）表达和处理的因素。我们较早的研究表明，我们的ACHE抑制剂Phenserine在体内降低了BAPP水平。因此，我们研究了Phenserine行动定义BAPP处理中的调节元素的机制。 Phenserine治疗导致培养的人类神经母细胞瘤细胞中可溶性BAPP和AB的分泌减少，而无需毒性。该活性与其作为抗胆碱酯酶的作用无关，但在转录后是因为它抑制了BAPP蛋白表达而不改变BAPP mRNA水平。这是通过BAPP mRNA的5'未翻译区（5 UTR）介导的。我们已经合成了新型药物来表征靶标，以及选择性和最佳调节BAPP mRNA翻译以减少AB合成。中风和帕金森氏病：中风和帕金森氏病（PD）目前使用的药物可暂时缓解症状，但不能防止细胞死亡。两种过程中的细胞死亡都是由称为凋亡的过程的结果，该过程可能是由线粒体损伤和氧化应激触发的。由于p53的上调被描述为几种神经退行性疾病的共同特征，并且是一系列生化事件的关键和限制性步骤，导致凋亡，它代表了干预药物发育的潜在目标。结果，我们最近设计和合成了一系列新型的四氢苯甲酸苯二唑类似物，这些类似物基于抗固有化合物Pifithrin-A的结构。目前正在评估化合物在组织培养和动物模型中的神经保护作用，以选择具有评估的药物作为候选药物。糖尿病：2型糖尿病是老年人的普遍疾病。它是由胰岛素的相对缺乏和胰岛素敏感组织中胰岛素作用降低引起的。目前的治疗不令人满意。在与M.D. Josephine Egan（糖尿病部分，LCS，NIA）的合作研究中，我们在GLP-1方面具有丰富的经验，GLP-1是一种肽，该肽是对食物的反应，是一种有力的促分泌物（即胰岛素），是对糖尿病的潜在治疗。当连续地注入糖尿病患者时，GLP-1的药理学浓度可以在其正常范围内维持血糖水平。然而，作为潜在治疗性的外源性治疗的GLP-1的主要缺点是其短暂的生物半衰期，在啮齿动物和人类中，它都可以在几分钟内清除。结果，GLP-1被用作开发更长的作用肽研究的起点，它是Exendin-4（一种来自Gila Monster Lizard的内源性肽，与GLP-1具有53％同源性共享53％的同源性，表明它是（i）更有效的，并且（II）维持比（II）更高的胰岛素及时（III）的持续时间（III）更长，（III）的效率更高（III）。 Exedin-4进入II期疗效研究，用于治疗2型糖尿病。结合了GLP-1和Exendin-4最佳特征的新型嵌合肽已设计，合成并正在评估各种细胞培养和动物模型中，以评估其临床发育的潜力。