The Food and Drug Administration on Monday approved a controversial drug to treat Duchenne muscular dystrophy, a rare disease that confines boys to wheelchairs and condemn them to an early death. The decision came after months of protracted debate about whether drug maker Sarepta Therapeutics had provided enough evidence to demonstrate that its medication, called eteplirsen, had a meaningful impact on patients.
In reaching its decision, the agency essentially overruled its own medical staffers, who earlier this year questioned the effectiveness of the drug over concerns about a small clinical trial. The wrangling raised still larger questions about standards for approving a drug, but some FDA officials also acknowledged that unmet medical needs for patients with some rare diseases warranted endorsement under a program known as accelerated approval.
“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,” said Dr. Janet Woodcock, who heads the agency division that reviews medicines, in a statement.
As a condition of the approval, however, Sarepta will have to conduct a two-year, randomized controlled trial to verify the clinical benefit of the drug. The purpose is to determine whether the drug actually improves motor functions. If the trial fails, the FDA could move to withdraw approval.
The approval delighted a frazzled, but vociferous community of parents, whose determined lobbying efforts were reminiscent of the movement three decades ago to force regulators to greenlight AIDS treatments. And the FDA endorsement also jazzed investors, who sent Sarepta shares soaring, while breathing new life into still other companies that are investigating Duchenne treatments. The stock was up 70 percent on the initial news.
The fate of the Sarepta drug has been closely watched as a litmus test for an intensifying struggle between the FDA and patient groups that want the agency to take a more expansive view toward approving medicines for unmet medical needs. In this instance, patient advocates hoped the FDA would use the accelerated approval process to endorse eteplirsen. This approach relies on a substitute outcome in a clinical trial to suggest a drug may have, but does not guarantee, a benefit.
It was a long and complicated road, however, to this moment, as the FDA and Sarepta squabbled repeatedly over several technical, but significant details.
A key issue was whether the drug can sufficiently produce higher levels of a protein called dystrophin. Without this protein, muscle fibers degenerate and voluntary movement becomes impossible. The FDA also raised doubts about the results of a small, 12-patient clinical trial that Sarepta relied on to make its case, as well as the viability of six-minute walking tests that trial participants underwent. Moreover, the company failed to conduct a larger trial involving the use of a placebo, as the FDA had requested.
In light of these concerns, an FDA advisory panel in April voted that the drug should not be approved and, by a narrow margin, also agreed that the drug does not appear to be effective. Their recommendations were made at a day-long meeting that was punctuated by a parade of emotional pleas from parents and children, some of whom appeared in wheelchairs.
Despite the outcome, the agency appeared to signal that parents should not lose hope. In remarks designed to appease the crowd, Janet Woodcock, who heads the agency division that approves drugs, said that “It’s possible to reach different conclusions based on the data presented today … Failing to approve a drug that actually works in devastating diseases—these consequences are extreme.”
And so, the FDA made an unexpected request for Sarepta to provide more data about muscle biopsies from 13 boys who participated in an ongoing trial in order to determine the extent to which the medicine may produce dystrophin. The move suggested that the FDA tried to find other ways to approve the drugs, although some believed the agency was attempting to lay the groundwork to argue that they had left no stone unturned before issuing a rejection.