By increasing the quantity of an abnormal, but potentially functional, dystrophin protein, the objective is to slow or prevent the progression of DMD. Nature and sequence of oligo and target
Eteplirsen is a morpholino phosphorodiamidate antisense oligomer. CTCCAACATCAAGGAAGATGGCATTTCTAG (sequence source: US FDA ETEPLIRSEN BRIEFING DOCUMENT NDA 206488),
30-mer,
20% G,
43% CG,
Predicted Tm: 88.9 °C at 10 μM oligo. Oligo complement
CTAGAAATGCCATCTTCCTTGATGTTGGAG
DMD-001 Exon 51, ENST00000357033.8 in Ensembl.org, RNA target site marked. Given that the target site is within an exon, this is likely blocking binding of an exonic splice enhancer protein and so altering splicing by interfering with splice regulation. CTCCTACTCAGACTGTTACTCTGGTGACACAACCTGTGGTTACTAAGGAAACTGCCATCT
CCAAA[CTAGAAATGCCATCTTCCTTGATGTTGGAG]GTACCTGCTCTGGCAGATTTCAACC
GGGCTTGGACAGAACTTACCGACTGGCTTTCTCTGCTTGATCAAGTTATAAAATCACAGA
GGGTGATGGTGGGTGACCTTGAGGATATCAACGAGATGATCATCAAGCAGAAG

Pharmacokinetics
Following single or multiple intravenous infusions, the majority of drug elimination occurred within 24 hours of intravenous administration. Elimination half-life of eteplirsen was 3 to 4 hours. History
New Drug Applications (NDA) for eteplirsen and a similar drug drisapersen were filed with the US Food and Drug Administration (FDA) in August 2015. The Prescription Drug User Fee Act (PDUFA) goal dates for these were December 27, 2015 for drisapersen and February 26, 2016, for eteplirsen. Following FDA rejection of drisapersen, the agency announced a three-month time extension for its review of eteplirsen. The FDA panel decision was controversial because the FDA staff and the panel used a stricter standard of evidence than Sarepta and patient groups used. The FDA panel said that it was required by law to apply the standard of "substantial evidence" of effectiveness. This required randomized, controlled trials showing effectiveness of a meaningful clinical outcome, such as the ability to function in daily life.
Eteplirsen (brand name Exondys 51) is a medication to treat, but not cure, some types of Duchenne muscular dystrophy (DMD), caused by a specific mutation. Eteplirsen only targets specific mutations and can be used to treat about 14% of DMD cases. Eteplirsen is a form of antisense therapy. Eteplirsen was developed by Steve Wilton, Sue Fletcher and colleagues at the University of Western Australia and commercialized by Sarepta Therapeutics. After a controversial debate surrounding the drugs efficacy, during which two FDA review panel members resigned in protest, eteplirsen received accelerated approval from the US Food and Drug administration in late 2016. The Committee for Medicinal Products for Human Use (CHMP) of the European Medicines Agency (EMA) refused to authorize the use of eteplirsen. Adverse effects
The following adverse events were observed in at least 10% of people who received eteplirsen in trials: vomiting, contusion, excoriation, arthralgia, rash, catheter site pain, and upper respiratory tract infection. Mechanism of action
Duchenne muscular dystrophy is caused when a mutation in the DMD gene changes the DMD mRNA so that it no longer codes for functional dystrophin protein, usually due to a nonsense mutation that introduces a premature stop codon into the mRNA. If an exon with an appropriate number of bases lies near the mutation, by removing the defective exon the downstream reading frame can be corrected and production of partially functional dystrophin can be restored.