Viltolarsen for the treatment of Duchenne muscular dystrophy

Duchenne muscular dystrophy is the most common lethal X-linked genetic disorder, characterized by progressive muscle loss, with cardiac and respiratory complications. It is caused by a lack of dystrophin protein due to mutations in the DMD gene, which can disrupt the reading frame of the dystrophin primary transcript. Antisense oligonucleotides such as phosphorodiamidate morpholino oligomers (PMOs) can induce exon skipping during pre-mRNA splicing and restore the reading frame of the DMD primary transcript. The resulting dystrophin protein is internally deleted but partially functional. Viltolarsen, also known as NS-065/NCNP-01, is a PMO developed through comprehensive sequence optimization and is designed to skip exon 53 on the DMD primary transcript. Exclusion of exon 53 from the DMD primary transcript can treat 8-10% of DMD patients worldwide. This review paper summarizes the mechanism of action, pharmacokinetics and safety of viltolarsen from preclinical and clinical trials.