A Proof of Concept Trial of a Sirtuin-NAD+ Activator in Alzheimer's Disease

总结 在临床前模型中，沉默调节蛋白-NAD+途径通过增加细胞内NAD+通过 给予NAD前体，如β-烟酰胺单核苷酸（βNMN）， 并预防或减弱阿尔茨海默病（AD）病理。与许多AD药物相比， 尽管AD的发病机制是靶向一种机制，但NAD前体可通过多种机制预防AD病理： 通过改善线粒体能量学;诱导淀粉样蛋白转换为非淀粉样蛋白生成加工 前体蛋白（APP）由于α-分泌酶活性增加;防止小胶质细胞依赖性Aβ毒性; 减轻神经炎症;促进神经元再生;和改善胰岛素作用。NAD- 前体是在柜台上出售的，尽管人们普遍声称它们的好处和越来越多的使用NAD 前体，其药理学，功效和安全性的仔细控制研究有限。 为回应检讨委员会的建议，我们已对研究报告作出广泛修订，现建议 一项在24名受试者中进行的小型、单中心、90天随机化、安慰剂对照、平行组、双盲试验 患有轻度AD痴呆的患者，以证明：1）CNS穿透血脑屏障的能力;和2） 口服NMN以增加大脑NAD水平，使用创新的超高场7 T磁共振 波谱（MRS）方法。为了确定βNMN是否穿透人类的血脑屏障，我们 将测量基线和基线时βNMN及其关键代谢物的脑脊液（CSF）浓度， 第90天（目标1）。我们将通过测量β-NMN的丰度来评估β-NMN是否参与靶机制。 使用超高场7 T MRS和外周血单核细胞中的脑中NAD+（SIRT 1底物） 使用经验证的LC-MS/MS测定法（目的2）。我们将确定βNMN对循环生物标志物的影响 老年科学专家建议的衰老（HbA 1C，IGF 1，T3，IL 6，TNFα和尿F2- 异前列烷）（目的3）。这项试验既不足够长，也不足够大，无法确定βNMN对 临床结果和AD生物标志物。然而，我们也包括了AD的CSF和血清生物标志物， 作为整体认知、日常生活工具性活动和神经精神症状的指标， 探索性结局，以估计设计参数，例如结局变化的偏倚和精密度，以及 前后相关性，以指导后续疗效试验的设计。 在拟议的原理证明试验中，科学的严谨性和创新性是通过使用一个高 βNMN的高质量结晶制剂;通过仔细进行药代动力学分析确定的给药方案 研究;严格的样品收集程序，以确保分析前的稳定性;以及评估参与情况 使用超高场7 T MRS研究大脑中的sirtuin-NAD+通路。该试验将提供重要的 关于目标机制参与情况的信息，这些信息对于指导逐步推进 这种有前途的分子用于更大的功效试验。

Summary In preclinical models, the upregulation of the sirtuin-NAD+ pathway by increasing intracellular NAD+ through administration of NAD precursors, such as β nicotinamide mononucleotide (βNMN), engages the mechanisms of aging and prevents or attenuates Alzheimer's disease (AD) pathology. In contrast to many AD drugs in development that target one mechanism, NAD precursors may prevent AD pathology by multiple mechanisms: by improving mitochondrial energetics; inducing a switch to non-amyloidogenic processing of amyloid precursor protein (APP) due to increased α-secretase activity; preventing microglia-dependent Aβ toxicity; attenuating neuroinflammation; promoting neuronal regeneration; and improving insulin action. NAD- precursors are sold over the counter, and despite widespread claims of their benefits and growing use of NAD precursors, carefully controlled studies of their pharmacology, efficacy, and safety have been limited. In response to the Reviewers' recommendations, we have extensively revised the study and now propose a smaller, single-site, 90-day randomized, placebo-controlled, parallel group, double-blind, trial in 24 participants with mild AD dementia to demonstrate: 1) CNS penetration across the blood-brain barrier; and 2) the ability of oral NMN to increase brain levels of NAD, using an innovative ultra-high field 7T magnetic resonance spectroscopy (MRS) method. To determine whether βNMN penetrates the blood-brain barrier in humans, we will measure the cerebrospinal fluid (CSF) concentrations of βNMN and its key metabolites at baseline and on day 90 (Aim 1). We will assess whether βNMN engages the target mechanism by measuring the abundance of NAD+ (a SIRT1 substrate) in the brain using ultra-high field 7T MRS and in peripheral blood mononuclear cells using a validated LC-MS/MS assay (Aim 2). We will determine the effects of βNMN on circulating biomarkers of aging that the geroscience experts have recommended (HbA1C, IGF1, T3, IL6, TNFα, and urinary F2- isoprostane) (Aim 3). This trial is neither long enough nor large enough to determine the effects of βNMN on clinical outcomes and AD biomarkers. However, we have included CSF and serum biomarkers of AD as well as measures of global cognition, instrumental activities of daily living, and neuropsychiatric symptoms as exploratory outcomes to estimate design parameters such as bias and precision of changes in outcomes, and pre-post correlation to guide the design of subsequent efficacy trials. The scientific rigor and innovation in the proposed proof-of-principle trial is underscored by the use of a high quality crystalline formulation of βNMN; a dose-regimen informed by carefully performed pharmacokinetic studies; rigorous sample collection procedures to ensure preanalytical stability; and evaluating the engagement of the sirtuin-NAD+ pathway in the brain using ultra-high field 7T MRS. The trial will provide important information on the engagement of target mechanisms that is necessary for guiding the stepwise progression of this promising molecule towards larger efficacy trials.