The U.S. Food and Drug Administration has approved a controversial treatment for Alzheimer’s, the first to promise to slow the destruction of the disease in the brain, not just improve symptoms.
The drug, adducanumab, is also the first new Alzheimer's treatment approved since 2003. It does not cure or reverse Alzheimer's disease, which affects more than 6 million people in the United States and is expected to affect nearly 13 million. of people by 2050.
The path to drug approval has not been smooth. In 2019, adducanumab was nearly discarded after it appeared unlikely to succeed in two major clinical trials. But after reanalyzing more data that came in later, the developer of the drug, Biogen, based in Cambridge, Massachusetts, saw signs that the drug might work in the end and decided to seek FDA approval (SN: 12/5 / 19).
Still, today’s decision refers to some doctors and scientists who see the FDA’s move as premature because they are not convinced that the drug, also known as Aduhelm, actually works. Adopting a drug that is not effective would cause Alzheimer’s research to backfire and offer patients false hope, those experts argue.
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“This is a great day for Biogen and its shareholders, but a bleak day for the field of Alzheimer’s research,” says Michael Greicius, a neurologist at Stanford University. Advancing in the "illusion of progress," he says, "will come at a cost to genuine progress in the search for effective treatment for this devastating disease."
Others disagree that the evidence is scarce and are delighted to have a new tool to combat a disease that has eluded effective treatment for so long. “We’ve been waiting for this for decades,” says neuroscientist Maria Carrillo, scientific director of the Alzheimer’s Association in Chicago. A drug that delays the decline due to Alzheimer’s promises to patients and their families to “maintain independence, keep memories longer, stay with families longer,” he says. "That's important."
The drug, which is administered intravenously, is a laboratory antibody targeting small and large groups of the sticky protein amyloid-beta. Some researchers suspect that in Alzheimer’s, A-beta upsets connections between nerve cells and damages brain tissue, ultimately causing Alzheimer’s symptoms. But that idea, called the amyloid hypothesis, has not yet been resolved (SN: 25/02/11).
Brain scans reveal that indiranumab is effective in reducing A-beta in the brain. What is less clear is whether this reduction includes consistent improvements in people’s quality of life. That uncertainty led an FDA advisory panel to firmly object to drug approval. In November, that group concluded that the evidence was too weak to show that the drug effectively treated Alzheimer’s (SN: 11/06/20).
Dudanumab has potentially serious side effects. Brain scans show that about 40 percent of people who received the highest dose of adducanumab in a clinical trial had swelling or bleeding in the brain. Although most of these people showed no symptoms, some had headaches, nausea, and dizziness.