Challenges and advances for metabolically stabilizing siRNA

Therapeutic oligonucleotides revisited: Focus on siRNA and antisense technologies

This review first provides a concise overview of the mechanistic principles underlying oligonucleotide function and commonly employed chemical modification techniques, and highlights recent advancements in receptor-mediated delivery systems for extrahepatic targeting, and dual-targeting oligonucleotide engagement strategies.

Balancing stability and biological activity in microRNA therapeutic design

“RNA therapeutics as a whole have garnered a great deal of attention, and I think it is the next frontier of therapeutics.” Jokūbas Leikauskas, Editor, Nucleic Acid Insights , speaks to Shreyas Iyer, Graduate Student Researcher, Purdue University, about the unique chemical modification challenges involved in stabilizing microRNA therapeutics without disrupting their natural biology, alongside the major delivery hurdles, particularly endosomal escape, facing the field. They close by outlining targeted delivery, endosomal escape, and deeper mechanistic understanding as the key areas poised to advance microRNA therapeutics over the next decade.

Optimized Chemical Modifications Enhance Lipid Nanoparticle-Mediated siRNA Silencing of YAP1 and WWTR1

Lipid nanoparticles (LNPs) are clinically validated carriers for the delivery of small interfering RNA (siRNA). Their efficient tissue accessibility and cellular uptake complement conjugated siRNA approaches. While chemical modifications are critical for stabilizing siRNAs and enhancing their potency (particularly in conjugated formats), their contribution in LNP delivery is not fully understood. Here, we systematically evaluated advanced sequence-modification patterns in siRNAs targeting YAP1 and WWTR1 to define their impact on LNP-siRNAs. We found that siRNAs fully incorporating 2′-O-methyl (2′-OMe), 2′-fluoro nucleotides achieved superior knockdown efficacy in vivo compared with partially modified LNP-siRNAs typically used in clinical drugs. Further increasing the proportion of 2′-OMe to 86% did not impair RNA interference activity, and DNA substitutions provide additional opportunities for structural optimization to collectively enhance knockdown efficacy in mouse liver. In contrast, 5′-(E)-vinylphosphonate modification of the guide strand provides no benefit to knockdown efficacy in vitro or in vivo, likely owing to differences in endosomal trafficking between LNP and conjugated siRNAs. These findings provide a framework for chemical optimization of LNP-based siRNAs. The generation of siRNAs with greater efficacy and longer durability facilitates lower doses with less frequent administration, which mitigates LNP-associated toxicity and improves the therapeutic potential of LNP delivery systems.

Current landscape of RNA chemistry and delivery in cancer immunotherapy

Small interfering RNAs (siRNAs) are programmable nucleic acids that play key roles in chemical biology and can selectively silence disease-associated genes through RNA interference (RNAi). These programmable nucleic acids have emerged as a powerful class of medicines and chemical biology tools that can rewire tumor-immune signaling, target immunosuppressive genes, stimulate immune responses, and boost the immune system against immune-mediated diseases. Recent success in the rapid synthesis and applications of siRNA highlights the potential of this technology to address previously “undruggable” targets across a range of genetic, metabolic, and oncologic diseases. Despite the potential of these siRNA-based therapies, including those used in cancer immunotherapy, challenges such as off-target effects during delivery, chemical degradation of siRNA in the body, and immunogenicity limit their efficacy. This review provides a comprehensive overview of the chemical biology and chemical modifications inherent to the design of robust siRNA therapies; the nucleic acid structure–function relationships that dictate the cellular mechanisms underlying siRNA-mediated gene silencing and efficacy; and the current clinical landscape and safety of approved siRNA therapeutics for immunotherapy. We examine the growing role of computationally guided design strategies and emerging machine-learning-based methods in optimizing siRNA chemical design, and outline how recent advances in siRNA chemical modification are expected to improve targeted gene modulation in the clinic. Additionally, we examine the role of delivery systems in enhancing siRNA potency, with an emphasis on tumor-targeted and tissue-specific approaches, as well as emerging combination therapies integrating siRNA with chemotherapy, immune checkpoint blockade, siRNA and mRNA co-delivery, and prodrug activation.

Advances in applications of siRNA in cancer therapy: challenges and opportunities.

RNA Therapeutics and Delivery Strategies: Innovations, Challenges, and Clinical Translation

A rapidly growing class of medications called RNA therapeutics could transform indi-vidualized treatment and target "undruggable" areas. The different forms of RNA-based treat-ments, such as messenger RNAs (mRNAs), small interfering RNAs (siRNAs), and circular RNAs (circRNAs), are discussed in this paper along with their significance in gene regulation and the treatment of disease. Stability and efficient distribution to target cells are major challeng-es for RNA molecules. Hydrogels, dendrimers, and lipid nanoparticles are being developed to improve RNA therapy pharmacokinetics and cellular absorption. More accurate and efficient therapies are also being made possible by breakthroughs in self-amplifying RNA (saRNA) tech-nology and the application of artificial intelligence in RNA delivery design. The review also dis-cusses RNA modifications and synthetic biology in pharmaceutical design. Although good data from preclinical and clinical trials demonstrate the potential of RNA-based therapeutics, further research is necessary to tackle translational difficulties and improve delivery mechanisms for therapeutic usage. RNA treatments may revolutionize medical research by treating cancer and genetic defects.