A historical perspective on the development of antisense oligonucleotide treatments for Duchenne muscular dystrophy and spinal muscular atrophy.

Splice modulating antisense oligonucleotides (ASOs) have been approved for the treatment of spinal muscular atrophy (nusinersen) and Duchenne muscular dystrophy (eteplirsen) since 2016. Nusinersen obtained full approval based on convincing functional evidence in treated patients. The treatment is currently approved in over 40 countries. By contrast, eteplirsen received accelerated approval and functional evidence from clinical trials that treatment slows down disease progression is still lacking. Approval and access is restricted to the USA and several countries in the Middle-East. In this historical perspective we look back to the development paths of these two ASOs focusing on the differences between the approaches, the target tissues and the diseases. Based on this we propose learnings for future development of ASOs for progressive neuromuscular diseases.