Programmed Instability of Ligand Conjugation Manifold for Efficient Hepatocyte Delivery of Therapeutic Oligonucleotides

Dynamic and static control of the off-target interactions of antisense oligonucleotides using toehold chemistry

Off-target interactions between antisense oligonucleotides (ASOs) with state-of-the-art modifications and biological components still pose clinical safety liabilities. To mitigate a broad spectrum of off-target interactions and enhance the safety profile of ASO drugs, we here devise a nanoarchitecture named BRace On a THERapeutic aSo (BROTHERS or BRO), which is composed of a standard gapmer ASO paired with a partially complementary peptide nucleic acid (PNA) strand. We show that these non-canonical ASO/PNA hybrids have reduced non-specific protein-binding capacity. The optimization of the structural and thermodynamic characteristics of this duplex system enables the operation of an in vivo toehold-mediated strand displacement (TMSD) reaction, effectively reducing hybridization with RNA off-targets. The optimized BROs dramatically mitigate hepatotoxicity while maintaining the on-target knockdown activity of their parent ASOs in vivo. This technique not only introduces a BRO class of drugs that could have a transformative impact on the extrahepatic delivery of ASOs, but can also help uncover the toxicity mechanism of ASOs.

Chemistry of Therapeutic Oligonucleotides That Drives Interactions with Biomolecules

Oligonucleotide therapeutics that can modulate gene expression have been gradually developed for clinical applications over several decades. However, rapid advances have been made in recent years. Artificial nucleic acid technology has overcome many challenges, such as (1) poor target affinity and selectivity, (2) low in vivo stability, and (3) classical side effects, such as immune responses; thus, its application in a wide range of disorders has been extensively examined. However, even highly optimized oligonucleotides exhibit side effects, which limits the general use of this class of agents. In this review, we discuss the physicochemical characteristics that aid interactions between drugs and molecules that belong to living organisms. By systematically organizing the related data, we hope to explore avenues for symbiotic engineering of oligonucleotide therapeutics that will result in more effective and safer drugs.