FDA closes door to speedy OK for Amicus rare disease drug
- Amicus Therapeutics is finding the Food and Drug Administration's touted regulatory flexibility has limits, announcing Monday that the agency would not currently consider an accelerated approval for its experimental therapy for Pompe disease.
- Instead, the FDA wants to see more clinical data and has offered feedback on a pivotal study that Amicus plans to begin in the second half of this year. Running that trial will take time, spurring Leerink analyst Joseph Schwartz to push back the drug's forecasted market launch to 2022 from 2019.
- Amicus isn't giving up on its push to submit the therapy to regulators sooner, however. The biotech said in a statement it would continue to build on its clinical data set to "support further discussions on a potential pathway for accelerated approval with the FDA in 2019."
Amicus has benefited from what some have judged to be a friendlier stance on the part of the FDA toward applications from industry for new drug approvals.
Its Fabry disease drug won FDA approval last month, roughly a year after the agency reversed course and dropped a requirement for further clinical study of the treatment. That ask had been made in 2016, under prior commissioner Robert Califf. Current FDA chief Scott Gottlieb appears to be taking a more flexible approach in an effort to balance patient need for new treatments with the desire for conclusive clinical evidence.
Yet there are limits to that stance, as some recent Complete Response Letters to drugmakers have illustrated.
In the case of Amicus' Pompe disease drug, the FDA apparently wasn't sufficiently convinced by positive results from an early-stage study to agree to reviewing the drug for accelerated approval.
Amicus had hoped to win a conditional approval while it conducts a larger, confirmatory study of the drug, which is currently dubbed AT-GAA. That trial will enroll up to 100 Pompe patients for a primary study period of up to 12 months.
Participants will be measured on a 6-minute walk test designed to evaluate whether AT-GAA can help restore muscle function. Results from the early study showed treatment helped patients who had never received enzyme replacement therapy (ERT) — the current standard of care — walk an average of nearly 42 meters further at six months than they did when beginning treatment.
Those who switched from treatment with ERT also saw a benefit, according to the results.
The FDA's position mirrors that of the European Medicines Agency, which in June told Amicus that the current data package for AT-GAA was "not sufficient" for a conditional marketing authorization application.
Amicus' planned pivotal study incorporated feedback from both the FDA and EMA and, if successful, would serve to support approval in both the U.S. and EU.
The company, however, still hopes to win over regulators to its view. In its Sept. 10 statement, Amicus said it would keep generating data to support applying for a speedier OK. In particular, results from up to 10 additional ERT-switch patients to be added to the ongoing Phase 1/2 study are expected in 2019. Longer-term follow-up data from the original 19 patients in that study are due later this year as well.
Leerink's Schwartz thinks those results could open up new dialogue with the FDA, but still pushed out the firm's forecast launch for AT-GAA to 2022.
Shares in Amicus were trading down by about 2% Monday morning.
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