Amylyx Pharmaceuticals Inc said on Thursday the U.S. Food and Drug Administration approved its drug for slowing the progression of ALS, or amyotrophic lateral sclerosis, and potentially delaying death, sending shares of the company up nearly 14 per cent in extended trading.

The company added healthcare professionals can soon write prescriptions for the drug, to be sold under the brand name Relyvrio, even as it works on the launch.

"We know people living with ALS have no time to wait and, for this reason, Amylyx is prepared to move quickly with commercialization in the U.S.," Co-Chief Executive Officers Josh Cohen and Justin Klee said in a statement.Amylyx's drug is a combination of generic compounds sodium phenylbutyrate and taurursodiol that work together to prevent nerve cells in the brain and spinal cord from dying prematurely.

ALS, also known as Lou Gehrig's disease, breaks down nerve cells in the brain and spinal cord that make muscles work, leading to progressive paralysis and death. It affects more than 30,000 patients in the United States, according to the patient advocacy group ALS Association. 

NOT A MAGIC TREATMENT

The average life expectancy of ALS patients is between two and five years, but some patients, such as Stephen Hawking, have lived for much longer. "I think we are all aware this drug is not the magic treatment that is going to cure the disease but will hopefully slow its progression," said Dr Jinsy Andrews, associate professor of neurology at Columbia University Vagelos College of Physicians and Surgeons, ahead of the approval.

Andrews, an investigator in Amylyx's ongoing late-stage trial, added that there was consensus across the ALS patient community that better treatments would be developed. Amylyx's drug has already been granted conditional approval in Canada, in June. Relyvrio becomes the third ALS drug to be approved by the FDA after Japanese firm Mitsubishi Tanabe's Radicava and the generic drug riluzole.

Goldman Sachs analyst Chris Shibutani earlier this month said he expects a strong adoption of the drug from the start and forecast annual sales reaching $767 million in 2026.SVB Securities analyst Marc Goodman forecast U.S. sales of over $1 billion for Amylyx's drug in 2026.

A RARE REVERSAL

Amylyx's case for approval was built on a recent analysis of clinical trial data said showed the drug slows the progression of the disease and extends life expectancy by nearly 10 months. Earlier this month, the FDA staff expressed concerns the additional analysis came from the same small mid-stage trial as initial data and could not be considered as a confirmation of the drug's benefits.

The agency's decision follows an approval recommendation, a rare reversal, from an outside panel of advisers which was reconvened in September to look at the new data analysis. The panel had previously recommended against the approval of the drug in March.

Billy Dunn, head of the FDA's Office of Neuroscience which reviewed the drug, had urged the advisers to consider "regulatory flexibility" in making their decision, saying the drug could be pulled from the market if it failed in a larger trial currently underway.

The FDA decision also follows months of lobbying by patients who urged the regulator to approve the drug based on its relative safety and the potential for increased survival.