FDA Extends Review Time for Pompe Disease Therapy

The FDA has extended the review by 90 days for Amicus Therapeutics’ AT-GAA, a therapeutic to treat patients with Pompe Disease, a genetic lysosomal disorder caused by deficiency of the enzyme acid alpha-glucosidase (GAA) that leads to severe muscle weakness that worsens over time.

AT-GAA contains two components: cipaglucosidase alfa, a recombinant human acid alpha-glucosidase (rhGAA) enzyme, and miglustat, a stabilizer of cipaglucosidase alfa.

The company had submitted two applications for this therapy, one for each component. This includes a biologics license application (BLA) for cipaglucosidase alfa, which has been extended to Oct. 29, 2022, and a new drug application (NDA) for miglustat, which has been extended to Aug. 29, 2022.

The FDA extended the PDUFA dates to allow additional time to review information submitted by the company as part of its ongoing reviews. The extension of the review timeline was not related to requests for any additional clinical data.

Amicus officials said in a press release that it expects the additional time will allow for the completion of the pre-license approval inspections necessary at the WuXi Biologics manufacturing site in China.

“We continue to work collaboratively with the FDA as it completes its review of the AT-GAA applications,” said John F. Crowley, chairman and chief executive officer at Amicus Therapeutics. “We want to thank the FDA for its continued diligence during the review process. We remain deeply committed to bringing AT-GAA to as many people living with Pompe disease as quickly as possible and delivering on our promise to become the potential new standard of care.”

The FDA had accepted Amicus’s filings for AT-GAA in September 2021. At that time, the FDA had set a PDUFA action date of May 29, 2022, for the NDA for miglustat and July 29, 2022, for the BLA for cipaglucosidase alfa.

The applications are based data from a phase 1/2 and phase 3 PROPEL studies, as well as data from an open-label extension study. In March 2022, Amicus released long-term data from the phase 1/2. Patients treated with AT-GAA for up to 36 months showed persistent and durable effects on six-minute walk test distance and other measures of motor function and muscle strength, stability or increases in forced vital capacity (FVC), and reductions in biomarkers of muscle damage and disease substrate. Side effects have been generally mild.

Results from the PROPEL study were published in November 2021 in The Lancet Neurology, which show that AT-GAA provided meaningful improvements over standard of care, even among those who had been receiving approved therapy for at least two years, a subgroup that has been shown to plateau or decline after several years on treatment.

The FDA has granted breakthrough therapy designation to AT-GAA for the treatment of late-onset Pompe disease. In the European Union, the marketing authorization applications were validated in the fourth quarter of 2021 and the Committee for Medicinal Products for Human Use (CHMP) opinion is expected in late 2022.