The drug is the first to show significant progress against the sticky brain plaques that are the hallmark of Alzheimer's disease.
The drug has proved highly effective at reducing the plaques, called beta-amyloid, that build up in the brains of people with Alzheimer's.
But does the drug actually slow the progression of the disease when it reduces the plaques? It's not yet clear. Two large studies offered conflicting evidence about whether the treatment slows declines in memory and thinking. A panel of expert advisers to the FDA recommended in November that the agency not approve the drug.
As a condition of approval, the FDA is requiring Biogen, the drug's maker, to conduct another clinical study to confirm that the reduction of amyloid plaques results in clinical improvement for patients. If the subsequent study doesn't show a clinical improvement, the agency could move to withdraw the approval.
There are also concerns that the FDA's approval will make it difficult for Biogen and Eisai, the companies marketing the drug, to find enough patients to participate in its next clinical trials as patients might not want to risk getting the placebo and can get the drug without being in a study.
The medicine will be marketed under the trade name Aduhelm.
The FDA acknowledged the controversy and attention the drug's approval has garnered from the Alzheimer's patient community, elected officials and others.
The agency opted to put Aduhelm on the FDA's accelerated approval pathway, which is meant to speed access to potentially valuable therapies for patients with serious diseases to serve an unmet need, and where a clinical benefit is expected — even if there is still some uncertainty about that benefit.
"[T]he Agency concluded that the benefits of Aduhelm for patients with Alzheimer's disease outweighed the risks of the therapy," Patrizia Cavazzoni, director of the FDA Center for Drug Evaluation and Research, said in a statement.
It could take several years to conclude the clinical trials the FDA is requiring. But in the meantime, Aduhelm will be available to patients.
Patients will receive the drug in monthly infusions. They will also need regular brain scans to detect a rare side effect: bleeding or swelling in the brain.
Biogen and Eisai said Monday that the annual wholesale cost for those taking maintenance doses would be $56,000 a year for a patient of average U.S. weight with mild cognitive impairment or mild dementia. The net price could change based on discounts and rebates.
Trading in Biogen shares was halted due to the announcement. After trading resumed midafternoon, shares were up more than $110, or 39%.
The Alzheimer's Association, which has been pushing for approval, applauded the news.
"This is the first drug that slows Alzheimer's disease. And, this is the beginning of a completely new future for Alzheimer's treatments," the group said in a statement. "This is a new type of Alzheimer's treatment; it addresses the disease in a way that has never been done before, compared to currently approved drugs."
But others say the drugmakers have not yet proved that aducanumab's benefits outweigh its risks.
In November, an FDA advisory committee of medical experts voted that the evidence did not show the drug to be effective at slowing Alzheimer's. One major study found that aducanumab slowed down the progress of Alzheimer's, while the other showed it didn't.
"Usually, you need two big studies finding the same thing to approve a drug," NPR reported after the vote last year. But at that meeting, "the FDA asked its experts to focus only on the positive study, and it also presented analysis of the data that was really very favorable to the drug. All of that did not go over well with these advisers. Some of them seemed to feel like they were being railroaded by the FDA."
An independent think tank also assessed the two phase 3 clinical trials of aducanumab and found the evidence "insufficient to conclude that the clinical benefits of aducanumab outweigh its harms or, indeed, that it reduces progression" of Alzheimer's disease.
Dr. Jason Karlawish, professor of medicine and medical ethics and an Alzheimer's expert at the University of Pennsylvania's Perelman School of Medicine, wrote last week that he would not prescribe aducanumab to his patients even with FDA approval, due to risks of small bleeds in the brain, financial cost and unclear benefits.
"[T]he data to make this case are murky and, even if they were clear, the drug's benefits are ambiguous at best and not worth this cost. Putting it on the market will stress Medicare's resources," he wrote.
MARY LOUISE KELLY, HOST:
Today the Food and Drug Administration approved a controversial drug to treat Alzheimer's disease. It's the first new treatment for the disease in nearly 20 years. It is also the first ever to treat the disease process underlying Alzheimer's. Joining us now to talk about the drug is NPR science correspondent Jon Hamilton.
JON HAMILTON, BYLINE: Hi.
KELLY: Hey. So give us the basics. What is this drug? How does it work?
HAMILTON: Well, until today, this drug was called Aducanumab. It will be marketed under the brand name Aduhelm. And it's meant for people in the early stages of Alzheimer's, you know, before memory and thinking have been severely affected. What this drug does is to help remove some of the sticky amyloid plaques that tend to build up in the brains of people with Alzheimer's. It will be given as a monthly infusion, so directly into the bloodstream. And patients on Aduhelm will need periodic brain scans because the drug can cause swelling in the brain.
KELLY: I mentioned this drug is controversial. How come?
HAMILTON: Because it's still not entirely clear how effective this drug is. Here's David Rind of the Institute for Clinical and Economic Review.
DAVID RIND: It's very hard to know right now whether this drug works and, if it does work, how well it works and whether any benefits it might have outweigh its harm.
HAMILTON: So the FDA reviewed two big studies of this drug. One showed that it helped patients. The other showed that it didn't. And a panel of scientists who advise the FDA said the agency should require another study before approving this drug. The FDA decided to approve it anyway, but they said the drug's maker will need to conduct that confirmatory study after the drug is already being sold.
KELLY: So questions about whether it will actually work. Where does that leave patients? Is having this drug on the market a good thing for Alzheimer's patients and their families?
HAMILTON: Well, you know, so at this point, having the drug - you know, you have groups like the Alzheimer's Association who say it is a good thing. And here's Harry Johns. He's the association's CEO.
HARRY JOHNS: Today, unlike yesterday, there is hope for a treatment that could add additional cognitive and functional time for an individual and for their loved ones.
HAMILTON: Right. So the Alzheimer's Association pushed really hard to get this drug approved. And their position is that having even a marginally effective drug will give patients hope and maybe some benefit. Until today, the only drugs out there just treated the symptoms of Alzheimer's - you know, the memory loss and that sort of thing. They did not treat the underlying disease. This drug has at least the potential of slowing down the disease by reducing plaques in the brain.
KELLY: OK, so that's the case for approving this drug. What about the other side? What are the downsides?
HAMILTON: Well, one fear is that people will have unreasonable expectations that this is some kind of a cure. I mean, it's not. And also it may become more difficult to study other new Alzheimer's drugs now because people won't want to gamble on some unknown treatment when there is already one out there that has been approved by the FDA.
KELLY: And before we let you go, Jon, how much is this going to cost?
HAMILTON: A lot, probably. The company is talking about a base cost of around $56,000 a year. But this drug - it has to be given in a medical setting, and it requires periodic brain scans. So the total cost is likely to be a lot more. And insurers, including Medicare, aren't going to pay the whole cost. So patients and their families could end up spending thousands of dollars a year out of pocket.
KELLY: NPR's Jon Hamilton - thank you, Jon.
HAMILTON: Thank you.
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