Duchenne muscular dystrophy is caused by mutations that halt dystrophin production, and exon-skipping therapies are tailored to specific mutation subsets. Amondys 45 (casimersen) serves patients amenable to exon 45 skipping.
Casimersen is a phosphorodiamidate morpholino antisense oligonucleotide that masks exon 45 during RNA processing, letting cells produce a shortened but partially functional dystrophin protein. Infused weekly, it treats patients with a confirmed mutation amenable to exon 45 skipping.
The approval was granted under the accelerated pathway based on increased dystrophin in skeletal muscle, leaving the confirmatory trial obligation as the key open question. It is one of several mutation-specific oligonucleotides from the same developer and relevant to tracking how the exon-skipping class matures.
