On second thought, Amicus won't be filing its lead drug this year

Amicus CEO John Crowley

Amicus Therapeutics ($FOLD), a biotech comeback story, is walking back plans to submit its rare disease treatment for FDA approval this year, rethinking its whole regulatory strategy after follow-up conversations with the agency.

In September, Amicus said it had a positive meeting with the FDA about migalastat, a treatment for the rare genetic disorder Fabry disease, and promised to submit the drug by year's end. However, looking over the minutes of that meeting this week, Amicus is no longer so bullish.

After "additional follow-up interactions" with the FDA, the company said it is now reconsidering how to move forward with migalastat in the U.S. The FDA wants "further integration" of the existing clinical data on the drug, Amicus said, which will take time to complete. And, more alarming, the company said it may need to run yet another trial on migalastat to determine its effect on gastrointestinal symptoms in Fabry, a prospect that would further delay its FDA submission.

The news sent Amicus' shares plummeting nearly 60% on Friday morning, reversing what had been a notable return from the depths.

The company reached its nadir in 2012 when migalastat missed its primary endpoint in a pivotal trial, and then-partner GlaxoSmithKline ($GSK) washed its hands of the drug shortly thereafter. But Amicus persevered, last year convincing the FDA to consider a different biomarker for improving Fabry symptoms and to evaluate migalastat solely in a subset of patients. The plan, as recently as last month, was to file the drug for accelerated approval based on surrogate endpoints and run postmarket studies to confirm migalastat's benefits for Fabry patients.

Now the New Jersey biotech is going back to the regulatory drawing board, "further evaluating several U.S. pathways" outside of accelerated approval. And Amicus said it can't speculate on the timing of a future FDA filing until it picks one.

"Amicus remains committed to making migalastat available to Fabry patients with amenable mutations in the U.S. as rapidly as possible," CEO John Crowley said in a statement. "We are appreciative of the FDA's ongoing collaboration in this program."

- read the statement

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