Sarepta files controversial Duchenne drug in EU

European regulators are to review Sarepta Therapeutics’ Duchenne muscular dystrophy drug, eteplirsen – a drug that has sparked controversy in the US, where it was approved by the FDA against the recommendations of its expert advisers.

US biotech Sarepta said the European Medicines Agency has accepted its filing for eteplirsen in Duchenne muscular dystrophy (DMD) patients amenable to exon 51 skipping – about 13% of the population with the rare muscle-wasting disease.

Sarepta seeks conditional approval following a review by the CHMP scientific committee based on early data – meaning the drug’s licence will have to be re-approved annually until confirmatory data are available.

The standard review period is 210 days, plus extra time for the applicant to respond to questions from the agency.

Eteplirsen binds to part of the pre-mRNA sequence, known as an “exon” and re-aligns it so that it produces a shorter, but functional version of the dystrophin protein that is lacking in patients with DMD.

Data from clinical studies of eteplirsen in a small number of DMD patients have demonstrated a consistent safety and tolerability profile.

But eteplirsen is controversial because it has been conditionally approved in the US, where it is now marketed as Exondys 51, even though its clinical benefit has not been established.

In Europe, PTC Therapeutics’ Translarna (ataluren) has already been approved, and in the UK has even been funded by the NICE cost-effectiveness body, despite its £220,000 a year price tag.

But the FDA earlier this year rejected a filing for Translarna, saying it did not meet its standards for efficacy.

The drug had failed endpoints in mid-stage trials but PTC had tried to argue that a post-hoc analysis in a subset of patients did show a benefit.

Sarepta’s drug made it through to an FDA advisory committee, which – despite a demonstration from patients and their families – said the drug was not effective.

The FDA delayed a decision as it considered the evidence, and the opinion of its advisory committee – and then conditionally approved the drug.

The news about the EU filing sparked a flurry of activity on twitter.

The EMA and FDA have very different decision-making processes, and although they often agree on whether drugs should make it to market, there’s no telling what will happen in this case.

The CHMP will have the same difficult job of balancing the need for a treatment for a devastating disease, and pressure from patient groups, against evidence that can only be described as flimsy.

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