Characterization of small molecules that lower mutant huntingtin protein as potential therapeutics for Huntington’s disease

摘要 亨廷顿病(HD)是一种常染色体显性、进行性和致命性神经退行性疾病。 影响全球20万人。尽管这种基因是在25年前和150多年前被发现的 临床试验表明，目前尚无有效的治疗HD的方法。任何减慢、停止、或 预防疾病将对患者及其家人产生重大影响。HD是由扩容引起的 在亨廷顿蛋白基因(HTT)中的CAG重复，导致亨廷顿蛋白中谷氨酸的扩展 蛋白。正常的亨廷顿蛋白(HTT)在整个身体和大脑中都是调节细胞生理所必需的 包括突触传递和神经保护、细胞分裂和分化、基因转录和 DNA损伤反应。在HD患者中，扩张的聚谷氨酰胺束导致突变的HTT(MHTT) 折叠异常，导致异常的翻译后修饰和切割，产生有毒的mHTT 碎片。N-末端mHTT片段形成与许多细胞蛋白相互作用的寡聚体，破坏 细胞功能，导致mHTT水平增加，并导致mHTT包涵体。实质神经元 纹状体中棘神经元(MSN)和大脑皮层出现功能障碍和死亡。实验 降低mHTT的程序可以逆转HD动物模型的疾病症状。然而，临床上 对这一作用机制的翻译已经停滞不前，部分原因被假设为非选择性降低 基本的HTT和mHTT。此外，临床试验中的一些候选药物针对的是 仅限于大脑，使用需要侵入性递送系统的治疗方式，并离开身体的其余部分 未经治疗。因此，一种口服的，系统分布的，脑穿透疗法，选择性地 消除有毒的mHTT，同时保留HTT的功能形式以支持正常生理，可提供 对所有HD患者有效治疗。通过应用其在筛查方面的专业知识，折纸治疗公司(OT) 鉴定了一种化学支架，由OR1-113表示，它可以防止mHTT聚集，并选择性地降低 细胞检测中通过自噬途径促进降解的mHTT水平 在HD患者来源的成纤维细胞中，人HD IPSC来源的中等刺神经元和活体皮质和 YAC128小鼠HD模型的纹状体。设计了12个ORI-113类似物。药效 并将比较OR1-113和12类似物在HD患者IPSC来源的MSN和 体外吸收、分布、代谢和排泄研究将提供有关新陈代谢的深入了解。 和药物化合物的潜在相互作用(目标1)。的药代动力学(PK)和脑暴露情况 从目标1中选择的四种先导化合物将在小鼠体内进行口服可利用度测定(目标2)。前两名 将在一项联合PK/药效学和安全性研究中评估排名的铅在YAC128小鼠中的口服 行政管理(目标3)。这些研究将确定一种主要的治疗药物候选药物，将进入 临床试验开始前需要进行的新药应用研究。

SUMMARY Huntington’s disease (HD) is an autosomal dominant, progressive and fatal neurodegenerative disease that effects 200,000 people worldwide. Despite discovery of the gene more than 25 years ago and more than 150 clinical trials, there is still no effective treatment for HD. The development of any therapy that slows, halts, or prevents disease would have a major impact on the patients and their families. HD is caused by the expansion of a CAG repeat in the huntingtin gene (HTT), resulting in an expanded stretch of glutamines in the huntingtin protein. Normal huntingtin protein (HTT) is essential throughout the body and brain to regulate cell physiology including synaptic transmission and neuroprotection, cell division and differentiation, gene transcription and the DNA damage response. In patients with HD, the expanded polyglutamine tract causes mutant HTT (mHTT) to fold abnormally, resulting in aberrant post-translational modifications and cleavage to generate toxic mHTT fragments. The N-terminal mHTT fragments form oligomers that interact with many cellular proteins, disrupting cell function, resulting in increased levels of mHTT and causing mHTT inclusions. Substantial neuronal dysfunction and death occur in striatal medium spiny neurons (MSNs) and the cerebral cortex. Experimental procedures that lower mHTT have reversed disease symptoms in animal models of HD. However, clinical translation of this mechanism of action has stalled and is, in part, hypothesized to be due to nonselective lowering of both the essential HTT as well as mHTT. In addition, some of the drug candidates in clinical trials target the brain exclusively, use therapeutic modalities that require invasive delivery systems and leave the rest of the body untreated. Therefore, an orally delivered, systemically distributed, brain-penetrant therapeutic that selectively eliminates toxic mHTT while sparing the functional forms of HTT to support normal physiology could offer an effective treatment for all HD patients. By applying its expertise in screening, Origami Therapeutics (OT) has identified a chemical scaffold, represented by OR1-113, that prevents mHTT aggregation, and selectively lowers mHTT levels in cell-based assays by enhancing degradation through an autophagy pathway as demonstrated in HD patient-derived fibroblasts, human HD iPSC-derived medium spiny neurons and in vivo in the cortex and striatum of the YAC128 mouse model of HD. Twelve analogues of ORI-113 have been designed. The efficacy and drug-like properties of OR1-113 and 12 analogues will be compared in HD patient iPSC-derived MSNs and in vitro absorption, distribution, metabolism, and excretion studies will provide insight regarding the metabolism and potential interactions of the drug compounds (Aim 1). Pharmacokinetic (PK) and brain exposure profiles of four lead compounds selected from Aim 1 will be determined in mice for oral availability (Aim 2). The top two ranked leads will be evaluated in a combined PK/Pharmacodynamic and safety study in YAC128 mice with oral administration (Aim 3). These studies will identify a lead therapeutic drug candidate that will move into Investigational New Drug Application studies that are required prior to initiation of clinical testing.