Amicus Therapeutics expects US filing delay for Fabry disease drug migalastat

Amicus Therapeutics' shares declined as much as 59 percent Friday after announcing it was unlikely to apply for US approval of its experimental Fabry disease drug migalastat by the end of the year, as it had recently suggested it would do, because the FDA asked the company for more information from clinical trials. According to Amicus, "the timing of a [new drug application] submission will be based on the determination of the optimal regulatory pathway."

Specifically, the FDA asked Amicus to further integrate data from previous clinical trials on migalastat, which the company said "will require more time to complete." Amicus also indicated it is working with the agency to assess "several US pathways, including potentially generating additional data on migalastat's effect on gastrointestinal symptoms in Fabry disease to support submission requesting full approval."

CEO John Crowley noted "Amicus remains committed to making migalastat available to Fabry patients with amenable mutations in the US as rapidly as possible," adding that "we are appreciative of the FDA's ongoing collaboration in this programme."

Last year, the company reported Phase III results from Study 012 demonstrating that migalastat efficacy was comparable to Sanofi's Fabrazyme (agalsidase beta) and Shire's Replagal (agalsidase alfa), the current standard-of-care enzyme replacement therapies (ERTs), and that it was also generally safe and well-tolerated. Prior to that, six-month data from Study 011 showed the drug had failed to significantly improve the proportion of patients achieving at least a 50-percent reduction in kidney interstitial capillary globotriaosylceramide levels, versus placebo.

In 2013, Amicus said it would delay its US filing for migalastat, which it had been co-developing with GlaxoSmithKline. However, the UK drugmaker has since returned the rights to migalastat, as well as a next-generation ERT for Fabry disease, back to Amicus. Migalastat has been awarded orphan drug status by regulators in the US, EU and Japan.

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