The U.S. Food and Drug Administration on Thursday approved Amylyx Pharmaceuticals Inc's drug for slowing progression of ALS, or amyotrophic lateral sclerosis, and potentially delaying death.

The Amylyx drug, to be sold under the brand name Relyvrio, is a combination of the generic compounds sodium phenylbutyrate and taurursodiol. The company says they 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 patient advocacy group The ALS Association.

Amylyx's case for approval was built on a recent analysis of clinical trial data that it said showed the drug slows progression of the disease and extends life expectancy by nearly 10 months.

The FDA's decision follows an approval recommendation from an outside panel of advisers in a rare reversal. The agency reconvened the panel in September to look at the new data analyzes after it had previously recommended against approving the drug in March.

Shares of the drugmaker were up nearly 7% in extended trading following the approval.