Thirty-six experts in the field of Duchenne muscular dystrophy have signed a letter to the FDA saying that, based on existing scientific data, the agency should approve eteplirsen (Sarepta Therapeutics), which is awaiting a final verdict. The letter was delivered to the FDA’s Division of Neurology Products as well as to Janet Woodcock, director of the Center for Drug Evaluation and Research, last month, but has just been made public by the University of California, Los Angeles (UCLA).
The letter was written by the two co-directors of UCLA’s Center for Duchenne Muscular Dystrophy––Drs. Stan Nelson and Carrie Micelli––and was signed by 34 other globally recognized Duchenne experts.
Current data suggest that the drug has worked for more than four years in a small trial involving 12 patients, but observers question whether these limited findings are sufficient to earn a positive decision from the FDA. A large confirmatory study is under way to confirm the results of the smaller trial.
Advocates argue that because eteplirsen has been effective in the four-year study and has shown no serious adverse effects, it warrants temporary approval since Duchenne muscular dystrophy is an extremely rare disorder, making large trials difficult to conduct. Moreover, no drugs currently exist to treat the disease.
In their letter to the FDA, the experts state: “We suggest that the most scientifically robust way forward and the most ethical choice for the Duchenne community is in the context of an accelerated approval followed by a confirmatory trial.”
The underlying cause of DMD is a mutation in the gene for dystrophin, an essential protein involved in muscle fiber function. Sarepta is developing investigational therapies for DMD that are designed to skip an exon in the dystrophin pre-m RNA to enable the synthesis of a functional shorter form of the dystrophin protein. Eteplirsen skips exon 51. Approximately 13% of Duchenne patients may be amenable to exon 51 skipping.