Novartis has disclosed, alongside its 2026 half-year results, that it submitted an application in the US for accelerated approval of delpacibart zotadirsen, an antibody-oligonucleotide conjugate (AOC) developed by Avidity Biosciences (now owned by Novartis), for Duchenne muscular dystrophy patients with exon 44-skipping mutations (DMD44). The candidate comprises a humanised anti-TfR1 antibody conjugated to multiple phosphorodiamidate morpholino oligomers (PMOs) that induce exon 44 skipping and restore dystrophin reading frame. Phase II EXPLORE44 data showed meaningful increases in exon skipping, dystrophin expression, and positive fibre percentage versus placebo, alongside functional improvements in the open-label extension.

The candidate represents one of only two AOC programmes globally to reach regulatory submission, the other being Dyne Therapeutics' zeleciment rostudirsen for exon 51-skipping DMD. By pairing muscle-targeted delivery with splice-modulating oligonucleotides, Novartis is positioning itself in the emerging RNA-antibody conjugate class alongside its broader neuromuscular and genetic medicine ambitions.