The drug, the third ALS drug approved in the US, destroys nerve cells needed for basic functions such as walking, talking and swallowing.

WASHINGTON – A a widely discussed drug for Lou Gehrig’s disease won approval in the US on Thursday, a long-awaited victory for patients that is likely to renew questions about the scientific rigor of government reviews of experimental drugs.

The Food and Drug Administration approved the drug from Amylyx Pharmaceuticals based on the results of one small, mid-stage study in which patients with the debilitating disease appeared to progress more slowly and survive several months longer. Generally, the FDA requires two large studies or one study with “very convincing” survival results for approval.

“This approval provides another important treatment option for ALS, a life-threatening disease that is currently incurable,” FDA Director of Neurology Dr. Billy Dunn said in a statement.

Relyvrio is the third drug approved in the US for amyotrophic lateral sclerosis, or ALS, which destroys nerve cells needed for basic functions such as walking, talking and swallowing. About 20,000 people in the US live with this disease.

The FDA review has become a flashpoint in a broader debate about the regulatory agency, including how flexible it should be in reviewing drugs for deadly diseases and how much weight it should give to patient feedback and other outside voices.

“I think it shows the FDA’s ability to be lenient, and I think it shows a lot of tenacity on the part of ALS patients and advocates,” said Dr. Kathryn Lomen-Hurt, an ALS specialist at the University of California, San Francisco. “The company really tried to do everything possible to make this potentially promising drug available to patients.”

The drug Amilix is ​​the last in a line with neurological drugs which received FDA approval despite questionable efficacy data. Agency still faces two government investigations to approve Alzheimer’s drug Aduhelm last year, which has yet to be proven to slow the disease.

In an online memo summarizing its decision, the FDA said “regulatory flexibility” is appropriate for Relyvrio’s approval “given the serious and life-threatening nature of ALS and the significant unmet need.”

The latest approval has had an extremely tumultuous journey, including two negative feedback by internal FDA scientists who called the company’s results “borderline” and “inconclusive.” A panel of external advisers supported this negative view in March, narrow voting against drugs.

But the FDA balked strong pressure from ALS patients, advocates and members of Congress. In recent weeks, the agency has received more than 1,300 written comments from the ALS community supporting the treatment.

The spill helped influence the same panel of experts when the FDA reconvened them earlier this month to review the drug Amylyx. The second time they supported the drug, 7-2. The vote was not binding but appeared to open the door to FDA approval.

Several panelists said they were also reassured by an unusual exchange at the meeting, in which the FDA’s Dr. Dunn asked — and Amylyx confirmed — that the company voluntarily withdraw its drug from the market if a large, ongoing study failed to confirm its benefit.

This study, involving 600 patients, is expected to produce results in 2024.

But experts pointed to many potential problems with such an informal commitment. The FDA and the company may disagree about whether the final data support the drug; or a company acquiring the drug in the future may not feel bound by Amylyx’s promise.

The powder-based drug is a combination of two old ingredients: a prescription drug for treating liver disease and a dietary supplement associated with traditional Chinese medicine. Amylyx, based in Cambridge, Mass., has patented the combination and says the chemicals work together to keep cells from dying prematurely.

Some ALS patients already take both drugs separately, sometimes paying $5,000 a month for the prescription component, doctors said. The FDA approval is expected to force insurers to cover the Amylyx drug.

Amylyx did not immediately disclose the price Thursday, but said it plans to make the announcement during a call with investors Friday morning. In Canada, where the drug was approved in June, the company offered a price of $165,000.

One third-party group that analyzes the cost-effectiveness of new treatments pegged the cost of the drug at between $9,100 and $30,700 a year. The Institute for Clinical and Economic Review also noted that many patients are expected to take the drug Amylyx in combination with older therapies that cost more than $170,000 a year.

Sunny Bruce was diagnosed with ALS in 2015, and hopes to add Relyvrio to the two older FDA-approved medications she already takes for the disease.

“I’ve made it this far without this drug, and I’m hoping that using it now will extend my life,” said Bruce, who is 35 and lives near Fort Worth, Texas.

The Amylyx data comes from a 6-month study in 137 patients that showed some benefit in slowing the disease, based on functionality questionnaires completed by patients. Patients who continued to take Relyvrio after the study ended seemed to survive longer than patients who initially received a placebo, the FDA noted.

“The ALS community has proven that our advocacy can influence the decisions that are made about our health,” Larry Falivena, an ALS Association board member who was diagnosed with the disease in 2017, said in an emailed statement. The group invested $2.2 million in Amylyx’s early-stage research and could recoup $3.3 million from drug sales.