Chemical Stabilization of shRNAs and their development as hepatitis C drugs

描述（由申请人提供）：丙型肝炎病毒（HCV）是一个全球性的健康问题，其治疗和预防仍然是一个重大挑战。现有的治疗方法只有部分有效，并有严重的副作用。目前没有疫苗可用。RNA干扰（RNAi）为治疗HCV感染提供了一种新的治疗方法。我们已经鉴定了一类称为sshRNA的shRNA，它们的长度更短，并且似乎通过与普通shRNA或siRNA不同的途径起作用。我们进一步鉴定了靶向HCV内部核糖体进入位点（IRES）的非常有效的sshRNA（IC 50 < 10 pM），IRES是病毒RNA的高度保守和必需但“不可用药”的部分。在第一阶段，我们测试了大量这些抑制剂的化学修饰版本，以发现修饰的类型和模式，这些类型和模式可以在血清中稳定它们而不影响它们的活性。我们确定了有效修饰的规则，并发现这种修饰消除了未修饰的sshRNA可能发生的对先天免疫系统的任何刺激，特别是如果它们是平端的。这些研究最近发表在RNA上的两篇论文中。在第二阶段，我们将：1）使用I期鉴定的规则合成我们的替代性前导shRNA的化学修饰版本，并验证它们的效力和缺乏免疫刺激特性; 2）找到前导shRNA的最佳组合以最小化shRNA介导的HCV病毒抗性变体; 3）使用小鼠报告模型完成纳米颗粒制剂的筛选以鉴定提供最佳sshRNA递送至肝脏的平台; 4）研究铅配制的shRNA的毒性;和5）验证铅配制的shRNA在支持HCV感染的动物模型中的治疗功效。完成这项工作后，我们将处于非常有利的地位，吸引合作伙伴资助剩余的IND使能临床前研究，提交IND，并继续进行临床试验。 公共卫生相关性：丙型肝炎病毒（HCV）是最常见的血液传播感染之一，也是一个全球性的健康问题。它是终末期肝病的主要原因，其治疗和预防仍然是一个重大挑战。RNA干扰（RNAi）为治疗HCV感染提供了一种有吸引力的新方法。我们已经确定了化学修饰的，高效的短发夹RNA（sshRNA）靶向HCV基因组的保守元件。本申请的目标是这些分子的临床前开发，以进行I期临床试验。

DESCRIPTION (provided by applicant): Hepatitis C virus (HCV) is a worldwide health problem, and its treatment and prevention remain a major challenge. Existing therapies are only partially effective and have serious side effects. No vaccine is currently available. RNA interference (RNAi) offers a novel therapeutic approach for treating HCV infections. We have identified a class of shRNAs, called sshRNAs, which have smaller length and appear to act via a somewhat different pathway than ordinary shRNAs or siRNAs. We have further identified very potent sshRNA (IC50 < 10 pM) targeting the HCV internal ribosome entry site (IRES), a highly conserved and essential but "undruggable" part of the viral RNA. In Phase I, we tested a large number of chemically modified versions of these inhibitors to find types and patterns of modification that would stabilize them in serum without compromising their activity. We identified rules for effective modification and found that such modifications eliminate any stimulation of the innate immune system that can occur with unmodified sshRNAs, particularly if they are blunt-ended. These studies were recently published in two papers in RNA. In Phase II, we will: 1) synthesize chemically modified versions of our alternative lead shRNA using the rules identified in Phase I, and verify their potency and lack of immunostimulatory properties; 2) find optimal combinations of lead shRNAs to minimize shRNA-mediated HCV viral resistant variants; 3) complete screening of nanoparticle formulations to identify the platform that provides the best sshRNA delivery to liver using a mouse reporter model; 4) investigate the toxicity of lead formulated shRNA; and 5) verify the therapeutic efficacy of lead formulated shRNA in an animal model that supports HCV infection. Upon completion of this work, we will be in a very strong position to attract a partner to fund the remaining IND-enabling preclinical studies, file an IND, and proceed with clinical trials. PUBLIC HEALTH RELEVANCE: Hepatitis C virus (HCV) is one of the most common blood-borne infections and a worldwide health problem. It is a major cause of end-stage liver disease and its treatment and prevention remain a major challenge. RNA interference (RNAi) offers an attractive new approach for treating HCV infections. We have identified chemically modified, highly potent short small hairpin RNAs (sshRNAs) targeting a conserved element of the HCV genome. The goal of this application is the preclinical development of these molecules toward a Phase I clinical trial.