Biomarkers to enable ASO prevention trials in genetic prion disease carriers

人类朊病毒病是一种罕见的，异常迅速的，普遍致命的神经退行性疾病。虽然 目前无法治疗的所有朊病毒疾病都遵循一种单一的明确的分子机制， 由朊病毒蛋白基因（PRNP）编码的天然朊病毒蛋白（PrP）错误折叠成致病性构象。 这些所谓的朊病毒模板的构象腐败的健康PrP分子，推动传播 朊病毒和朊病毒引起的神经毒性。作为朊病毒转化的必要底物， 天然PrP已成为朊病毒疾病中有吸引力的治疗靶点。数十年的证据表明， 天然PrP的减少对朊病毒疾病具有剂量依赖性保护作用。全面淘汰赛授予总 预防疾病，动物和人类的证据表明，减少PrP应该是很好的， 容忍。鉴于这些有希望的概念证明，我们正在与Ionis Pharmaceuticals合作， 开发降低PrP的反义寡核苷酸（ASO），通过靶向PrP RNA降低脑中的PrP， 降解初步的临床前研究表明，抗朊病毒蛋白的ASO有效地延长了 朊病毒感染的动物，预防性治疗提供了最大的好处。我们的初步约定 与FDA的合作表明，对症状前朊病毒病突变携带者进行的一级预防试验可以 是可行的，降低脑脊液（CSF）中的PrP可能是加速的一个可行的替代终点 一种降PrP治疗药物的批准。根据FDA的参与情况，以下三个目标将收集关键的 1）评估短期受试者内的重测稳定性 CSF PrP在症状前遗传性朊病毒病突变携带者和非携带者对照中的作用。我们将 使用经技术验证的ELISA测定重复捐献的CSF样本中PrP水平的短期稳定性 遗传性朊病毒病携带者和对照者在2-4个月的时间间隔内。2)确定以下各项之间的相关性 大鼠脑和CSF PrP敲低，以及小鼠脑PrP敲低与存活之间的关系。我们将 分析ASO处理的啮齿动物组织，以模拟脑和CSF PrP水平之间的关系，以及 脑PrP敲低与生存期延长之间的关系。3)收集病理生物标志物数据 为了评估在症状前患者中是否存在生物化学可检测的朊病毒病前驱期， 人类携带者我们将分析症状前人血浆和/或CSF样本中的神经元标志物， 朊病毒种子的损伤和存在，已知与症状性朊病毒疾病相关的生物标志物， 出于试验设计和分层的目的，了解症状前携带者是否显示出 在症状发作之前的生化可检测的病理前驱期。

Human prion disease is a rare, exceptionally rapid, universally fatal neurodegenerative disease. Though currently untreatable, all prion disease follows a single well-characterized molecular mechanism by which the native prion protein (PrP), encoded by the prion protein gene (PRNP), misfolds into a pathogenic conformation. These so-called prions template the conformational corruption of healthy PrP molecules, propelling the spread of prions and prion-induced neurotoxicity across the brain. As the necessary substrate for prion conversion, native PrP has emerged as an attractive therapeutic target in prion disease. Decades of evidence indicate that reduction of native PrP is dose-dependently protective against prion disease. Full knockout confers total protection against disease, with animal and human evidence indicating that PrP reduction should be well tolerated. In light of these promising proofs of concept, we are collaborating with Ionis Pharmaceuticals to develop PrP-lowering antisense oligonucleotides (ASOs) that reduce PrP in the brain by targeting PrP RNA for degradation. Preliminary preclinical studies suggest that ASOs against prion protein potently extend survival of prion-infected animals, with prophylactic treatment conferring the greatest benefit. Our preliminary engagement with the FDA indicates that primary prevention trials in pre-symptomatic prion disease mutation carriers could be feasible, and that lowering PrP in cerebrospinal fluid (CSF) may be a viable surrogate endpoint for Accelerated Approval of a PrP-lowering therapeutic. Informed by FDA engagement, the following three aims will gather critical and time-sensitive data to enable this clinical path. 1) Assess short-term within-subject test-retest stability of CSF PrP in pre-symptomatic genetic prion disease mutation carriers and non-carrier controls. We will use a technically validated ELISA to determine short-term stability of PrP levels in repeat CSF samples donated by genetic prion disease carriers and controls over 2-4 month intervals. 2) Determine the correlation between brain and CSF PrP knockdown in rats, and between brain PrP knockdown and survival in mice. We will analyze ASO-treated rodent tissues to model the relationship between brain and CSF PrP levels, as well as the relationship between brain PrP knockdown and extension of survival. 3) Gather pathological biomarker data to assess presence of a biochemically detectable prodromal phase of prion disease in pre-symptomatic human carriers. We will analyze pre-symptomatic human plasma and/or CSF samples for markers of neuronal damage and presence of prion seeds, biomarkers known to be associated with symptomatic prion disease, to understand for purposes of trial design and stratification whether pre-symptomatic carriers show evidence of a biochemically detectable pathological prodromal phase prior to symptom onset.