Antisense Oligonucleotides with 5′-decoy technology triggers nonsense-mediated decay of SCN9A to elicit long-lasting analgesia

The voltage-gated sodium channel NaV1.7 (SCN9A) is a genetically validated target for pain therapy, but achieving therapeutic isoform selectivity remains a formidable challenge for small-molecule inhibitors. Here, we overcome this bottleneck through a highly selective RNA-targeted strategy that dictates SCN9A alternative splicing. We first identified ASO50 as the most potent baseline candidate antisense oligonucleotide (ASO). Subsequent 5'-decoy (5D) sequence screening yielded an upgraded candidate, L9C-ASO50, which is engineered to competitively intercept U1 snRNA, achieving a cooperative spatial hindrance that robustly suppresses exon 5 recognition. This targeted exon exclusion introduces a frameshift that triggers robust, obligate transcript clearance via the nonsense-mediated mRNA decay (NMD) pathway, ensuring complete functional silencing without cross-reacting with homologous NaV channels. Mechanistically, we define the underlying cis-trans regulatory architecture, revealing a homeostatic tug-of-war where the RNA-binding protein ELAVL2 enforces exon inclusion, paradoxically antagonized by the canonical SR protein family. Crucially, CNS-restricted delivery of L9C-ASO50 produces profound and sustained mechanical and thermal analgesia. These findings establish splice-modulated transcript degradation as a viable therapeutic paradigm for chronic pain and provide a broadly applicable blueprint for engineering targeted RNA therapeutics.