Shares in Amicus Therapeutics plunged as much as 28 percent after the company disclosed that the FDA does not consider reductions in the biomarker globotriaosylceramide (GL-3) a basis for seeking accelerated approval of migalastat for Fabry disease. CEO John F. Crowley remarked "while we believe that the totality of the data from our studies...support the submission of a new drug application today, we acknowledge the FDA's position that accelerated approval based on kidney GL-3 reduction is not currently an option."
Instead, the agency asked Amicus to conduct another clinical study of migalastat to collect new data on gastrointestinal (GI) symptoms in Fabry patients who have an amenable mutation, with results expected in 2019. The company indicated that the primary endpoint of the 12-month trial, which is expected to start enrolling patients next year, will be to assess diarrhoea based upon established FDA irritable bowel syndrome guidance.
Crowley commented "we have...defined a plan to collect additional GI data to support full approval for migalastat that we believe is feasible in a reasonable amount of time and with a high likelihood of success based on positive GI data generated in our previous Phase III Study 011." Results  from Study 011 showed a significant decrease in diarrhoea in patients with amenable mutations treated with migalastat versus placebo during the six-month double-blind phase, which persisted after 18 to 24 months of treatment with the drug.
Migalastat was approved  earlier this year in Europe, where it is marketed as Galafold, as a first-line therapy for the long-term treatment of adults and adolescents aged 16 years and older with a confirmed diagnosis of Fabry disease and who have an amenable mutation. Amicus noted that it has launched Galafold in Germany and is undergoing the EU country-by-country processes to launch in the majority of European countries throughout 2016 and 2017.