LONDON, Sep 19 (APM) - The U.S. Food and Drug Administration (FDA) on Monday announced the first approval for a drug for rare muscle-wasting condition Duchenne muscular dystrophy (DMD) in the U.S.
Sarepta's eteplirsen was granted accelerated approval by the FDA under the brand name Exondys 51 to treat patients who have a confirmed mutation of the dystrophin gene amenable to exon 51 skipping, which affects about 13% of the population with DMD.
The accelerated approval scheme allows drugs for serious diseases to be authorised in the U.S. based on earlier stage data while the company conducts clinical studies to verify the predicted clinical benefit.
The decision is a significant moment for the DMD community in the U.S. and for Sarepta, which has faced several hurdles this year in getting approval from the FDA.
An advisory committee to the FDA was meant to assess the drug as a DMD treatment in January, but this was postponed due to snowstorms on the east coast of the U.S., causing the FDA to delay a decision on the drug from late February to May 26 (APMMA 46283).
In that time, a group of leading U.S. doctors in DMD wrote a letter to the FDA urging the regulator to approve eteplirsen, describing accelerated approval as the "most ethical choice" for the regulator considering the severity of the condition - which leads to premature death - and the lack of viable treatments (APMMA 47019).
However, when the advisory committee finally met in April to discuss eteplirsen they narrowly voted that there was not enough evidence to prove the drug was effective (APMMA 47557).
The FDA in May then delayed a decision on the drug a second time as it was not possible to make a decision in time for the deadline (APMMA 48000), before announcing in June that it requested more data from Sarepta, with the company agreeing to submit data from 13 patient biopsy samples, at baseline and week 48, to the FDA (APMMA 48182).
This was enough to satisfy the FDA for an accelerated approval, with the regulator announcing that the data submitted by Sarepta demonstrated Exondys 51 can lead to 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.
DMD is caused by an absence of dystrophin, a protein that helps keep muscle cells intact. People with the condition progressively lose the ability to perform activities independently and often require use of a wheelchair by their early teens before dying in their late 20s or early 30s.
However, the FDA added that the clinical benefit of Exondys 51, including improved motor function, has not been established. Under the conditions of the accelerated approval, the FDA is requiring Sarepta to conduct a trial to assess whether the drug improves motor function, and if the trial fails to verify clinical benefit, the FDA may initiate proceedings to withdraw approval of the drug.
Janet Woodcock, director of the FDA's Center for Drug Evaluation and Research, said: "In rare diseases, new drug development is especially challenging due to the small numbers of people affected by each disease and the lack of medical understanding of many disorders.
"Accelerated approval makes this drug available to patients based on initial data, but we eagerly await learning more about the efficacy of this drug through a confirmatory clinical trial that the company must conduct after approval."
In Europe, PTC Therapeutics was the first company to have a DMD drug approved when regulators backed Translarna (ataluren) under conditional approval in 2014. The drug remains the only DMD treatment approved in the region, and is now available and reimbursed in several countries.
However, the U.S. filing for Translarna was also turned down by the FDA in February this year, with the regulator commenting that the company's filing was incomplete.
BioMarin announced in May its plans to discontinue development of Kyndrisa (drisapersen) as a treatment for DMD after the FDA rejected the drug, and European regulators looked to be going the same way (APMMA 48100).
Santhera also faces a lengthy delay for a decision on its drug Raxone (idebenone) in order to complete a trial. Other companies working in the area include Summit Therapeutics (APMMA 49562).
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