Chemical engineering of therapeutic RNAs for extrahepatic delivery

项目摘要 小干扰RNA(SiRNAs)是一种信息性药物，可以设计用来治疗由基因决定的 疾病，从而重塑我们对待人类医学的方法。SiRNAs的临床应用取决于 功能递送到感兴趣的组织和细胞类型，这又由寡核苷酸化学定义。 当一种化学结构--即寡核苷酸修饰模式--提供功能性和非功能性 对组织的毒性传递是优化的，可以快速开发候选药物来治疗其他疾病 同样的组织受累。目前，siRNA的临床应用仅限于肝脏，其中结合 三价N-乙酰半乳糖胺(GalNAc)部分可有效地递送到肝细胞和治疗 一次注射后一年的活动量。 为了将siRNAs的用途扩展到肝脏以外的组织，我们必须(I)优化化学修饰模式，以 完全稳定的siRNA，无毒并与沉默机制兼容；(Ii)了解 确定siRNA药代动力学和药效学行为的机制；以及(3)确定和 设计新的配体，使其能够靶向组织传递并保持体内疗效。我们有 在有机化学、组合化学、寡核苷酸化学、RISC 生物学和siRNA药理学需要解决这些问题。到目前为止，我们已经完全从化学上确定了 表现出最小毒性和免疫原性的稳定的siRNA支架；经工程设计的新型结合物 支持对肝脏、肾脏、心脏、脂肪、肌肉和肺的功能性递送；定义了化学方法来 动态调节siRNA清除；合成新的主干修饰(膦酸变异体) 这提高了siRNA的稳定性，当放置在指定的位置时，增强了RISC的效力和特异性。 在这些最新进展的基础上，我们提出了四个主要的研究方向，寻求(I)化学 能够使体内任何RNA序列完全稳定和持续有效的工程siRNA支架； (2)建立作为调节治疗性RNA特性的新的主干的磷酸酸盐变体；(3) 设计和发现新的配体，将siRNA输送到肝脏以外的组织；以及(Iv)与网络合作 的专家合作者，以研究新的化学配置在模型中的治疗潜力 医疗需求未得到满足的疾病。 这些研究的完成将建立能够实现肝外功能的siRNA化学结构 SiRNAs的传递，并导致发现几种有可能改变治疗方法的化合物 针对一系列疾病的治疗方法。

Project Summary Small interfering RNAs (siRNAs) are informational drugs that can be designed to treat genetically defined disorders and thereby reshape our approach to human medicine. The clinical utility of siRNAs depends on functional delivery to a tissue and cell type of interest, which is in turn defined by oligonucleotide chemistry. When a chemical architecture—i.e., oligonucleotide modification pattern—that provides functional and non- toxic delivery to a tissue is optimized, candidate drugs can be quickly developed to treat other diseases with the same tissue involvement. Currently, the clinical utility of siRNA is limited to liver, where conjugation of trivalent N-acetylgalactosamine (GalNAc) moiety enables efficient delivery to hepatocytes and therapeutic activity for a year after a single injection. To expand the utility of siRNAs to tissues beyond liver, we must (i) optimize chemical modification patterns that fully stabilize siRNAs and are non-toxic and compatible with the silencing machinery; (ii) understand the mechanisms that define siRNA pharmacokinetic and pharmacodynamic behavior; and (iii) identify and engineer novel ligands that enable targeted tissue delivery and sustained in vivo efficacy. We have the demonstrated expertise in organic chemistry, combinatorial chemistry, oligonucleotide chemistry, RISC biology, and siRNA pharmacology needed to solve these problems. To date, we have identified fully chemically stabilized siRNA scaffolds that exhibit minimal toxicity and immunogenicity; engineered novel conjugates that support functional delivery to liver, kidneys, heart, fat, muscle, and lung; defined chemical approaches to dynamically modulate siRNA clearance; and synthesized novel backbone modifications (phosphonate variants) that improve siRNA stability and, when placed in defined positions, enhance RISC efficacy and specificity. Building on these recent advances, we propose four principal research directions that seek to (i) chemically engineer siRNA scaffolds that enable complete stability and sustained efficacy of any RNA sequence in vivo; (ii) establish phosphonate variants as a new backbone for the modulation of therapeutic RNA properties; (iii) engineer and discover novel ligands that deliver siRNAs to tissues other than liver; and (iv) work with a network of expert collaborators to investigate the therapeutic potential of novel chemical configurations in models of diseases with unmet medical needs. The completion of these studies will establish siRNA chemical architectures that enable functional extrahepatic delivery of siRNAs and lead to the discovery of several compounds with the potential to transform therapeutic approaches for range of diseases.