Sarepta has indicated that there could be a delay to getting its Duchenne muscular dystrophy therapy Exondys approved in Europe, revealing that the European Medicine Agency’s Committee for Medicinal Products for Human Use’s trend vote was negative.

“Based on discussions with CHMP representatives, it is our understanding that the CHMP did not conclude that eteplirsen is ineffective for exon 51 amenable patients, but rather that Sarepta has not yet met the regulatory threshold for conditional approval, in part due to the use of external controls as comparators in the studies,” said Doug Ingram, Sarepta’s president and chief executive.

Sarepta is now planning to file for re-examination and will request that a Scientific Advisory Group (SAG) - made up of DMD and neuromuscular specialists, be convened “to provide expert guidance and insight into, among other things, the validity of the external controls used and the importance of slowing pulmonary decline in patients with DMD,” he added.

Exondys 51 addresses the underlying cause of DMD by enabling the production of a functional dystrophin protein, and clinical studies have demonstrated a broadly favourable safety and tolerability profile as well as efficacy for the drug.

The injection is specifically indicated for patients who have a confirmed mutation of the dystrophin gene amenable to exon 51 skipping, which affects about 13 percent of the DMD population.

In 2016, US regulators issued a conditional approval for the therapy after concluding that the data submitted by Sarepta demonstrated an increase in dystrophin production that is reasonably likely to predict clinical benefit in some patients with DMD who have a confirmed mutation of the dystrophin gene amenable to exon 51 skipping.

But it also stressed at the time that a clinical benefit had not been established, and so asked the firm to carry a further clinical trial to convert the conditional approval into a full one.