A newly approved drug called lecanemab is offering hope for people affected by Alzheimer’s disease. But what is lecanemab, and how does it slow the progression of dementia?
There are around 6.5 million people in the U.S. living with Alzheimer’s disease, and that number is increasing every year. Alzheimer’s disease is the most common form of dementia in older adults and the seventh leading cause of death in the U.S. Prior treatments have failed to slow the progression of the disease, leaving people and their families few options following a diagnosis.
However, there are new reasons to be cautiously hopeful about treatment: The U.S. Food and Drug Administration (FDA) recently granted accelerated approval to the drug lecanemab. Currently being used for people in the early stages of Alzheimer’s disease, lecanemab appears to actually slow the progression of cognitive decline.
While this is an exciting development for people living with Alzheimer’s and their families, it’s important to note that the drug is still being evaluated. This means that doctors can currently prescribe lecanemab, but the FDA has not finished fully evaluating its effectiveness and potential side effects.
Additionally, lecanemab has been shown to cause certain adverse side effects in some people, so it’s not the best option for everyone. Below we answer some pressing questions about this promising new drug and explain what it means to be granted accelerated approval from the FDA.
What Is Lecanemab?
Marketed under the name Leqembi, lecanemab targets the progression of Alzheimer’s disease rather than simply alleviating some of its symptoms. It was granted accelerated approval by the FDA after the results of an 18-month Phase 3 trial were published in the New England Journal of Medicine in November 2022. The Phase 3 trial found that lecanemab reduced cognitive decline by 27%—a promising result for people in the early stages of Alzheimer’s disease.
How Does Lecanemab Work?
Lecanemab is a monoclonal antibody. These types of drugs work by introducing lab-made molecules into the bloodstream to act as substitutes for the body’s natural antibodies and immune cells that aren’t functioning properly.
In this case, lecanemab binds to amyloid beta proteins—the main component of the amyloid plaques (clumps of misfolded proteins) found in the brains of people with Alzheimer’s. These amyloid plaques eventually damage the brain, resulting in cognitive decline and dementia. By binding to amyloid beta proteins, lecanemab reduces the formation of these amyloid plaques, in turn potentially reducing some of the brain damage that causes Alzheimer’s symptoms.
What Does It Mean That Lecanemab Received Accelerated FDA Approval?
The FDA’s Accelerated Approval Program allows for faster approval of drugs designed to treat serious conditions where there is currently a lack of effective treatments available. The drug must be shown to clearly affect a specific marker or measurement of a disease—such as the reduction of amyloid plaques in the brain—that is likely to result in successful treatment outcomes. This is different from the usual requirement for approved drugs to show that they definitely result in a measurable change in symptoms.
Once accelerated approval is granted, drug companies must still conduct studies to confirm the expected benefit of the medication—in this case, slowing the progression of cognitive decline in people with Alzheimer’s disease. If clinical trials confirm that the drug performs as expected, then the FDA grants traditional approval. If not, its accelerated approval may be revoked and the drug can be removed from the market.
The accelerated approval of drugs can be life-changing for people with previously untreatable and incurable diseases like Alzheimer’s. Earlier approval gives more people access to treatments that may significantly affect their symptoms and quality of life.
Potential Risks and Serious Side Effects
It’s important to note that drugs in the accelerated approval stage can have risks and side effects that have yet to be fully studied or understood. Not all people with Alzheimer’s will be good candidates for lecanemab.
Lecanemab’s Phase 3 trial revealed adverse side effects for 14% of those who took the drug, compared to 11.3% in the placebo group. The most commonly reported serious side effects were nausea, vomiting, and changes in blood pressure, as well as amyloid-related imaging abnormalities (ARIA) shown on MRI scans.
ARIA usually presents as brain swelling, sometimes accompanied by bleeding in the brain or on the brain’s surface. Some people experience dizziness, confusion, nausea, headache, seizures, and vision changes, though there are not always obvious symptoms. ARIA can occasionally cause hospitalization or lasting impairment. There have been three deaths linked to lecanemab’s extended trials, with the FDA continuing to evaluate the potential for serious side effects.
Next Steps in Alzheimer’s Treatment
The price of lecanemab is another concern. It currently costs $26,500 per year, and there is no guarantee that insurance companies will cover it. The Center for Medicare and Medicaid Services is currently reviewing lecanemab in light of its accelerated approval, but says that for now it will be covered only for people enrolled in registered clinical trials.
Despite the potential drawbacks, lecanemab’s accelerated approval is still an exciting development for people with Alzheimer’s disease. While it’s not a cure, lecanemab may be able to positively impact the lives of people in the early stages of the disease.
“These peer-reviewed, published results show lecanemab will provide patients more time to participate in daily life and live independently,” says the Alzheimer’s Association. “It could mean many months more of recognizing their spouse, children, and grandchildren.”
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