The F.D.A. has approved only two other A.L.S. medications. Riluzole, a tablet approved in 1995, can extend survival by several months and generally costs significantly less than $10,000 a year. Edaravone, marketed as Radicava, can slow symptom progression by about 33 percent. Radicava, which was originally approved in 2017 as an intravenous infusion, was approved this year in an oral form that carries a list price of $171,000 a year. Amylyx officials said they expected that, as in the company’s clinical trials, many patients would take Relyvrio, a powder that is mixed with water, along with one or both of the other medications.
Relyvrio was conceived by the founders of Amylyx, Mr. Klee and Joshua Cohen, when they were undergraduate students at Brown University less than a decade ago. They proposed that combining taurursodiol, an over-the-counter supplement sometimes used to regulate liver enzymes, and sodium phenylbutyrate, a prescription medication for a pediatric urea disorder, could protect neurons in the brain from damage in diseases like A.L.S. by preventing dysfunction of two structures in cells: mitochondria and the endoplasmic reticulum.
In an interview, Mr. Klee said the company expected that private insurers would cover the drug with no co-payments for patients, and he said that Amylyx would work to make it affordable for people on Medicare or Medicaid and provide it free to those without insurance who are financially struggling. Mr. Klee noted that patients had been obtaining the ingredients on their own for some time, buying the taurursodiol supplement from Amazon and paying up to $11,000 a month for the sodium phenylbutyrate.
“Now that our product is approved, we have to be laser-focused on making sure that people can access it,” Mr. Klee said.
Relyvrio’s clinical trials included patients who developed symptoms of A.L.S. within 18 months before the trial and were affected in at least three body regions, which is generally a sign of fast-progressing disease. The F.D.A.’s approval did not restrict which patients could use the medication. Mr. Cohen said in an interview that Amylyx didn’t have projections of how many would.
“There are patients who are just receiving the diagnosis today, and there are patients who are making end-of-life decisions today, and I think that people in different circumstances are going to make very different treatment decisions,” he said.
Amylyx has also conducted a small trial of Relyvrio in Alzheimer’s patients, and Mr. Cohen discussed plans to test it for other neurodevelopmental disorders.
“We conceived the drug to try to target pathways of neuronal death,” he said, “and neuronal death is an important part of not just A.L.S. but potentially many diseases.”