By Leroy Leo
(Reuters) – Advisers to the U.S. Food and Drug Administration will discuss Sarepta Therapeutics Inc’s gene therapy for Duchenne muscular dystrophy (DMD) at a closely-watched meeting on Friday, days after the agency raised concerns over clinical trial data on the therapy.
The potential one-time treatment is the first gene therapy for the rare muscle-wasting disorder to reach the FDA’s doorstep, and could change the way patients with the disease are treated if approved.
DMD is estimated to affect one in 3,500 male births worldwide, according to the National Organization for Rare Disorders, causing progressive muscle failure. Most people with DMD do not survive beyond their thirties.
Sarepta’s currently approved DMD therapies only treat a subset of patients with certain gene mutations. Other treatments include corticosteroids that have side effects if used long-term, such as excess weight gain and osteoporosis.
In a mid-stage trial, Sarepta’s gene therapy was able to produce a mini version of the dystrophin protein needed to help keep muscles intact, but did not improve patient clinical outcomes like walking and standing ability.
That data was criticized by FDA staff reviewers in briefing documents published on Wednesday, saying the trial did not provide “unambiguous evidence” that the gene therapy will benefit patients with DMD.
Sarepta is conducting a late-stage trial, with data expected in September, that may be better able to demonstrate the therapy’s benefits.
Investors are hoping it will gain an accelerated approval, which would allow the treatment on the market based on surrogate biomarkers that predict the likelihood of benefit, versus hard clinical outcomes, such as improved physical function or extended survival.
A top FDA official, Peter Marks, said in March the FDA is moving to encourage use of disease related biomarkers that may predict efficacy for gene therapies for diseases with small patient populations.
Evercore ISI analysts put the chance of approval at 50%-60%, while SVB Securities analyst Joseph Schwartz said the FDA briefing documents create a shaky backdrop for the advisory panel.
The FDA typically follows the advise of its independent experts but is not obligated to do so. The agency is expected to make a final decision on the therapy by the end of the month.
(Reporting by Leroy Leo in Bengaluru; Editing by Manas Mishra and Bill Berkrot)
