Evolution of antisense oligonucleotides: navigating nucleic acid chemistry and delivery challenges

INTRODUCTION: Antisense oligonucleotide (ASO) was established as a viable therapeutic option for genetic disorders. ASOs can target RNAs implicated in various diseases, including upregulated mRNA and pre-mRNA undergoing abnormal alternative splicing events. Therapeutic applications of ASOs have been proven with the Food and Drug Administration approval of several drugs in recent years. Earlier enzymatic stability and delivery remains a big challenge for ASOs. Introducing new chemical modifications and new formulations resolving the issues related to the nuclease stability and delivery of the ASOs. Excitingly, ASOs-based bioconjugates that target the hepatocyte have gained much attraction. Efforts are ongoing to increase the therapeutic application of the ASOs to the extrahepatic tissue as well. AREA COVERED: We have briefly discussed the mechanism of ASOs, the development of new chemistries, and delivery strategies for ASO-based drug discovery and development. The discussion focuses more on the already approved ASOs and those in the clinical development stage. EXPERT OPINION: To expand the clinical application of ASOs, continuous effort is required to develop precise delivery strategies for targeting extrahepatic tissue to minimize the off-target effects.