Amylyx Pharmaceuticals (Nasdaq:AML) has won FDA approval for Relyvrio (AMX0035; sodium phenylbutyrate and ursodoxicoltaurine), notching the first win for amyotrophic lateral sclerosis (ALS) in five years.
The drug received Health Canada approval in June. The drug is known as Albrioza in that country.
In a summary, FDA reviewers note that the limited clinical data available for the drug have resulted in “in a degree of residual uncertainty about the evidence of effectiveness” of the drug. The agency notes that the lack of clarity is acceptable given the significant disease burden of ALS.
“This approval provides another important treatment option for ALS, a life-threatening disease that currently has no cure,” said Dr. Billy Dunn, director of the Office of Neuroscience in the FDA’s Center for Drug Evaluation and Research, in a news release. “The FDA remains committed to facilitating the development of additional ALS treatments.”
AML shares were up 10.47%, hitting $33.35 in after-hours trading.
Its stock initially traded at $18.07 after its initial public offering on January 7, 2022.
Amylyx has yet to disclose the price for the drug in the U.S.
Other companies developing drugs for ALS include the biotech QurAlis with its novel molecule QRL-201 and Irvine, California-based Eledon Pharmaceuticals with tegoprubart.
Patient-advocacy groups such as the ALS Association have lobbied for the FDA approval of Relyvrio. The ALS Association donated $2.2 million to fund its development.
A Phase 2 study found that the combination of Relyvrio and the approved ALS drugs Riluzole (Rilutek) and edaravone (Radicava) resulted in a 25% reduction in disease progression at six months.
The Phase 2 CENTAUR trial involved 137 participants with ALS. Meeting its primary endpoint, the study had a six-month randomized placebo-controlled phase and an open-label extension long-term follow-up phase.
While FDA reviewers generally require Phase 3 results, its decision to approve the drug with Phase 2 data is an example of “regulatory flexibility. “[T]he single study with positive results on a clinically meaningful primary outcome accompanied by confirmatory evidence of an observed survival benefit provides substantial evidence of effectiveness,” FDA reviewers noted in a summary. “The benefits of AMX0035 outweigh the risk, as the drug appears well tolerated without any significant safety signals of concern.”
A 48-week Phase 3 study is underway. Results from that study are expected in 2024.
In March, however, an FDA advisory committee expressed skepticism about the drug’s potential to help ALS patients. The panel recommended against approval in March.
The FDA extended its initial deadline for deciding whether to approve the drug after a March meeting of an advisory committee that narrowly voted that the drug hadn’t been proven effective.
After that decision, FDA extended its deadline to decide whether to approve Relyvrio.
In early September, however, the FDA advisory committee reversed its decision, voting seven to two to recommend FDA approval of Relyvrio.