FDA on Thursday approved a new drug to treat amyotrophic lateral sclerosis (ALS) from Amylyx Pharmaceuticals—the first new treatment for the disease in five years. And while ALS patients and advocates have praised the move, some health experts have voiced concerns about the drug's efficacy.

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FDA approves new ALS drug for the first time in 5 years

ALS, also known as Lou Gehrig's disease, is a relatively rare neurological disorder that destroys motor neurons in the spinal cord and brain, leading to weakened muscles, paralysis, and death. The disease often progresses rapidly, and many ALS patients die within two to five years of their diagnosis.

In the United States, around 30,000 people are currently living with ALS, and 6,000 new cases are diagnosed every year. Currently, only two drugs have been approved by FDA to treat ALS: riluzole, which was approved in 1995, and edaravone, which was approved in 2017. Both drugs have limited effectiveness.

On Thursday, FDA approved a new ALS drug from Amylyx Pharmeceuticals, which will be sold under the brand name Relyvrio. The drug consists of two generic medications, taurursodial and sodium phenylbutyrate, and is designed to slow ALS progression by protecting nerve cells in the brain and spinal cord.

According to the Washington Post, FDA based its approval on a 24-week Phase 2 study of 137 patients who randomly received Relyvrio or a placebo. The patients who received the drug saw a 25% slower rate of decline when performing essential activities, including walking and talking, compared to patients who received a placebo.

In its initial data submitted to FDA, Amylyx said that the drug helped patients live a median of 4.8 months longer than patients in the placebo group. Earlier this month, Amylyx presented a new analysis that estimated patients who received the treatment would have lived a median of 9.7 months longer than those received the placebo.

"This approval provides another important treatment option for ALS, a life-threatening disease that currently has no cure," said Billy Dunn, director of the FDA's office of neuroscience.

So far, Amylyx has not stated how much it will charge for the drug but said that its "goal is that every person who is eligible for Relyvrio will have access as quickly and efficiently as possible as we know people with ALS and their families have no time to wait."

FDA's back and forth on approving the drug

Based on Amylyx's initial submission, FDA reviewers said they were skeptical of the analyses and did not believe the data adequately supported the treatment's efficacy. In March, FDA's advisory committee narrowly voted 6-4 against approving Relyvrio.

However, patients and advocates sent FDA more than 10,000 emails campaigning for the treatment's approval, arguing that it had not received the same flexibility as new medicines for Alzheimer's and other neurological disorders, including Biogen's Aduhelm.

In response, FDA extended its initial deadline for the decision about the drug's approval and allowed Amylyx to submit more data. On Sept. 7, a second advisory committee met to reconsider the drug's approval.

At the meeting, FDA reviewers stood by their initial assessment and said they still considered the new data insufficient. However, the advisory committee ultimately voted 7-2 in support of approving Relyvrio after Amylyx officials said they would voluntarily withdraw the drug from the market if a larger trial was not successful.

In an online memo summarizing its decision, FDA said "regulatory flexibility" was acceptable in Relyvrio's approval because of the "the serious and life-threatening nature of ALS and substantial unmet need."

"It's hard to put into words how significant this approval is for the thousands of Americans who are living with ALS and their families," said Larry Falivena, a trustee of the ALS Association who was diagnosed with the disease in 2017. "The ALS community has proven that our advocacy can impact decisions that are being made about our health."

Will the drug make a difference for ALS patients?

Currently, some drug policy experts say there is insufficient evidence to show that Relyvrio is effective. Although Amylyx is conducting a larger clinical trial of the treatment with 600 patients, the results will not be available until late 2023 or early 2024.

"There is some evidence to support the efficacy of the product, but I don't think it hits the bar that the FDA typically requires," said G. Caleb Alexander, an internist and epidemiologist at the Johns Hopkins Bloomberg School of Public Health and a member of the FDA advisory committee that reviewed Relyvrio. "How much should the FDA lower the bar—if at all—for products for a devastating disease" that does not have effective treatments?

Diana Zuckerman, president of the National Center for Health Research, agreed with Alexander. "How many ineffective ALS drugs do we need?" she said. "It would be better to have one that has been proven to make a meaningful difference to live longer."

However, ALS specialists have largely applauded the approval, and many have said that they plan to prescribe the drug to their patients as soon as it's available.

"I see patients living with this disease, and I diagnose them every day," said Jinsy Andrews, an associate professor of neurology and director of neuromuscular clinical trials at Columbia University. "So to have another therapy for the tool kit is helpful." (Garde, STAT, 9/29; Walker, Wall Street Journal, 9/30; McGinley, Washington Post, 9/30; Belluck, New York Times, 9/29; Perrone, Associated Press, 9/30; FDA news release, 9/29)