The efficacy of oligonucleotide-based gene therapeutics in gene silencing

Oligonucleotide-based gene therapeutics (OGTs) have emerged as a promising strategy for treating a variety of diseases, offering a tool for gene modulation at the mRNA level. Despite significant progress in OGTs development, their efficacy in both experimental and clinical settings has often fallen short of expectations. Current estimates suggest that less than 1% of transfected OGTs are released into the cytosol, significantly limiting the interaction with target RNA. Moreover, data suggests that only about 2% of the tested siRNAs achieve the expected 70% target gene knockdown in vitro. Clinically approved OGTs appear to be effective only against genetic disorders that lack effective alternative treatment, and even in these cases their therapeutic contribution remains marginal. Notably, the majority of approved OGTs, as well as those currently in clinical trials, are antisense oligonucleotides (ASOs) despite cell culture data showing that small interfering RNAs (siRNAs) exhibit greater potency. The delayed commercialization of siRNAs, despite high research interest, may be attributed to passenger stand-dependent off target effect and the immaturity of their design and modification strategies. This review critically evaluates the factors influencing therapeutic efficacy of OGTs and highlights the persistent gap between theoretical promise and clinical reality.