The FDA Just Approved a “Milestone” Alzheimer’s Drug

On Thursday, the FDA approved the use of Leqembi (lecanemab) as a treatment for early Alzheimer’s disease. It is the first drug to show clear evidence for slowing down memory loss for people in the early stages of the condition.

“Leqembi is the first fully FDA approved drug that is disease modifying for Alzheimer’s disease; a milestone in this field,” says Thomas Wisniewski, the director of Alzheimer’s Disease Research Center at NYU Langone Health. “However, the drug is appropriate for a select set of patients with early disease and the clinical benefits are relatively modest.”

While Leqembi does not reverse or cure Alzheimer’s, the FDA’s recent approval makes it possible for people who are eligible for the drug to access it. Leqembi was first given accelerated approval in early January but since it did not undergo the complete approval process, Medicare refused to cover it. At a steep price tag of $26,500 a year, people had to pay out of pocket for this medication. The FDA’s latest decision paves the way to expand Medicare coverage for this drug in people 65 years and older — the age group most affected by Alzheimer’s.

Leqembi is a type of antibody that targets clumps of protein fragments in the brain called amyloid-beta plaques. For reasons scientists still do not fully understand, piles of protein begin sticking together between neurons and eventually these clumps become hard to avoid as their presence interferes with neurons sending important chemical messages to each other. 

The plaques also disrupt the cellular functions needed to keep neurons alive. Deprived of nutrients to sustain itself and unable to call for help, the neuron dies. There is also research suggesting the toxicity of amyloid-beta plaques stimulates the release of an immune cell called microglia. Microglia acts as the janitor of the brain, sweeping up any cellular debris and dysfunctional cells. The messy situation of amyloid-beta plaques could create an uncontrolled immune response where microglia crowd around the plaques as a way to limit neurotoxicity while also releasing inflammatory responses that injure nearby cells. 

Leqembi stops this neurodegenerative process from happening by reducing the number of amyloid-beta plaques in the brain. As an antibody, Leqembi hunts down the beta-amyloid protein. Once found, it tags the protein which tells the immune system that it needs to be removed from the body immediately. The decrease in amyloid plaques is expected to slow down disease progression and delay cognitive impairments, which could add up to extra time patients can spend with their loved ones.

The drug is a liquid administered as an intravenous infusion. The recommended dosage is 10 mg/kg delivered for one hour once every two weeks. The dosage can change depending on the amyloid-beta plaques in the brain.

Strong results from a phase 3 clinical trial testing the effectiveness of Leqembi convinced the FDA that the antibody is capable of preserving cognition in people with Alzheimer’s.

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