Good news or bad news? FDA delays decision for Amylyx's ALS drug—and shares rise

This could be good news, or bad news. Amylyx Pharmacueticals has received notice from the FDA that the decision date for its amyotrophic lateral sclerosis drug has been extended.

The therapy was voted down by an agency advisory committee in March in a tough vote that followed riveting patient testimony and calls for a shot at a potential treatment option. The FDA does not have to follow the advice of the committee, but these votes usually portend the outcome on a drug application.

Now, the FDA wants a bit more time to consider if AMX0035 can be approved to treat the progressive neurodegenerative disease. The agency will now act by September 29, a three-month extension from the original end-of-June date.

The FDA extended the timeline to review additional analyses of data submitted by the biotech. These additions to the new drug application were deemed a major amendment so the FDA's reviewers needed more time, the company said Friday (PDF).

“We are confident in the potential of AMX0035 to help people living with ALS and other neurodegenerative diseases, and we continue to work closely with the FDA as they complete their review,” said Justin Klee and Joshua Cohen, Co-CEOs and co-founders of Amylyx.

Investors appeared confident that the delay is a good sign. Shares of Amylyx rose 36% in pre-market trading Friday morning to $13.32 compared to $9.77 at close the day before. 

Amylyx’s application for AMX0035 is underpinned by a phase 2/3 trial called Centaur and an open-label extension, which showed a slowing of disease progression in patients with ALS. But the single study was “not exceptionally persuasive,” according to briefing documents the FDA released ahead of the March advisory meeting. The company is already conducting a phase 3 trial called Phoenix but was hoping for an accelerated approval in the meantime.

The accelerated approval pathway has been in the spotlight for the past year since the FDA granted one to Biogen and Eisai’s controversial Alzheimer’s disease therapy Aduhelm. Some industry watchers predicted the FDA might be more open to doing the same for Amylyx given AMX0035 may provide an option for patients who do not have any others and will rapidly progress. But the patient advocates, who called for access now, were unable to persuade the committee members, who flagged issues with missing data and the problematic single study.

AMX0035 is a combination of sodium phenylbutyrate and taurursodiol.