FDA changes tune on Amicus Fabry disease drug
- In a reversal, the Food and Drug Administration will allow Amicus Therapeutics to file for approval of its Fabry disease drug migalastat based on existing clinical evidence, dropping its previously communicated requirement for an additional year-long pivotal study.
- Amicus now plans to submit a New Drug Application for migalastat in the fourth quarter of this year, roughly two years ahead of when it could likely expect to do so if the FDA had continued to require the additional Phase 3 trial.
- Newly minted FDA Commissioner Scott Gottlieb has indicated his desire to speed regulatory review of new drugs and pushed the agency to become more flexible. The rare change of heart on Amicus' drug, as well as recent approval of a new indication for Vertex's cystic fibrosis drug Kalydeco (ivacaftor) based on real-world and in vitro data, can be seen as signs of that new approach.
While Gottlieb has unveiled new plans to foster greater competition in generic markets, the FDA under its new chief is looking more industry friendly for drugmakers looking to bring new products to market.
Rare disease drug developers, in particular, will likely cheer the FDA's reversal on Amicus' migalastat. The biotech had hoped to submit for approval on the basis of a Phase 3 study which had shown a reduction in a fatty substance known as GL-3 for patients with certain genetic mutations amenable to the drug.
In patients with Fabry disease, an enzyme that typically works to break down GL-3 doesn't work properly, leading to an accumulation of GL-3 in cells and subsequent organ damage.
Last year, the FDA told Amicus reduction in GL-3 levels would not be considered a basis for accelerated approval, requiring instead a 12-month, placebo-controlled cross-over study. That study would have involved roughly 35 patients, pushing back Amicus' timeline for migalastat in the U.S. significantly.
Now, the FDA has dropped that requirement and Amicus plans to hustle a New Drug Application in to regulator's desk by the end of the year.
The U.S. is the single largest market opportunity for migalastat, according to Amicus. The drug is already approved in Europe for those Fabry patients with amenable mutations and has been used in just over 100 patients as of the end of April
Since Amicus' study did not show a statistically significant benefit in patients without those mutations, any future approval for migalastat would likely be limited to the segment of the patient population most likely to benefit — as is the case in Europe.
Amicus estimates between 35% to 50% of Fabry patients globally carry the genetic mutations considered amenable to migalastat.
News of the FDA's reversal boosted shares in the company by more than 20% in value, propelled by the considerably hastened regulatory pathway to a potential approval.
A larger question, though, is whether the decision on Amicus is indicative of a more welcoming and flexible attitude on the part of the FDA towards experimental rare disease drugs. Clearing a path for an application does not mean the FDA will end up approving the drug, of course, but given Gottlieb's known attitudes on hastening approvals, drugmakers may be encouraged by the news.
- Amicus Therapeutics Press release
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