Casimersen sodium is an antisense oligonucleotide of the phosphorodiamidate morpholino oligomer subclass. Casimersen sodium binds to exon 45 of dystrophin pre-mRNA, restores the open-reading frame (by skipping exon 45) resulting in the production of an internally truncated but functional dystrophin protein. Casimersen sodium can be used for the research of Duchenne muscular dystrophy (DMD)^[1].