Lecanemab: Status of EISAI and Biogen New Alzheimer’s Drug

Last Updated: July 12, 2021


What is Lecanemab?

Another drug by the makers of Aduhelm (the newest Alzheimer’s medication, approved by the FDA in June 2021) is being tested and might also offer relief for people in the early stages of Alzheimer’s disease. It’s called lecanemab, and clinical studies show that it may help the brain by reducing the buildup of harmful plaques between cells.

Lecanemab is a monoclonal antibody designed to attach itself to amyloid-beta and signal the immune system to attack. For people in the early stages of dementia, the reduction of amyloid-beta protein tangles can help with thinking and memory. Alzheimer’s disease is progressive, meaning it gets worse over time, but researchers believe the progression can be slowed down if those harmful amyloid-beta plaques are reduced in the brain.

As the number of Alzheimer’s cases climbs above 6 million in America, new pharmaceuticals offer hope for treatment. The FDA, in fact, has already begun working with lecanemab’s creators to speed up the process toward approval. For more on when lecanemab might become available to the public, see below.


Benefits & Side Effects of Lecanemab

It looks like lecanemab reduces the development of harmful amyloid-beta plaques in the brains of people with mild Alzheimer’s disease, and therefore slows down the devastating effects of the disease. Lecanemab cannot cure Alzheimer’s, but someone with the disease can potentially hold onto memories and mental sharpness for a longer period of time by taking the medication.

The companies that make lecanemab, Eisai and Biogen, are currently in Phase 3 of clinical trials. In Phase 2, 856 people with mild Alzhiemer’s disease were given either lecanemab or a placebo.

Tests during Phase 2 showed the following, compared to placebo:

– Those who received lecanemab had less amyloid-beta in their brains
– The progression of dementia symptoms slowed down

Placebos are like a sugar pill. Administering a placebo to half the people in the study gives researchers a comparison to see if the drug is working. And researchers can tell whether someone’s decline in memory and thinking is faster or slower than normal by using the integrated Alzheimer’s Disease Assessment Scale, which combines brain scans and tests including the Mini Mental State Exam with an evaluation of how well instrumental activities of daily living (IADLs) like using a phone or preparing meals can be performed.

Promising test results for lecanemab earned the drug a “breakthrough therapy” designation from the Food and Drug Administration in June 2021. This means lecanemab has shown enough promise that it was put on a faster track toward FDA approval, a process requiring time-consuming reviews of research and study data.

Side Effects
Researchers said there was an association in trial subjects between lecanemab and greater brain-volume loss (specifically in the hippocampus, which holds memories) than the subjects who took placebo. Some subjects who took the drug also saw a higher rate of amyloid-related imaging abnormalities (ARIA, also called “cerebral edema”), which are associated with brain swelling.


How Lecanemab Works

Lecanemab is an antibody that sticks to clumps of amyloid-beta found in the brains of people with Alzheimer’s disease. The drug signals the immune system to attack those clumps and clear them out. More specifically, lecanemab is a protofibril antibody that was designed to attack amyloid-beta in the brains of mice and then, after promising results, modified to work similarly in humans with mild Alzheimer’s disease.

Amyloid-beta is a protein found in healthy brains, but people with Alzheimer’s disease have been shown to experience a notable buildup of these proteins around brain cells. The buildups turn over time into plaques that affect communication between cells. Before becoming plaques, however, amyloid beta in brains with Alzheimer’s collect into fibrils, which are smaller than plaques but can cluster together into plaques that appear on PET and MRI scans of people with the disease. It’s during that stage, before the plaques form, that lecanemab can target and help reduce the amount of amyloid-beta.

Compared to Other Alzheimer’s Medications
Lecanemab is made in part by the company Biogen, which grabbed headlines in June 2021 when their drug Aduhelm (generic name aducanumab) became the first Alzheimer’s drug to receive FDA approval in almost 20 years. Both lecanemab and aducanumab are administered intravenously. Aducanumab and lecanemab both target amyloid-beta, though in slightly different ways. A big distinction is obviously that aducanumab has achieved FDA approval and is available now, whereas lecanemab is probably still years away. More information on aducanumab (brand name Aduhelm) is available at this link.

Other medications that specifically target Alzheimer’s disease and related dementias are cholinesterase inhibitors (brand names Aricept, Razadyne, and Exelon) and memantine (brand name Namenda). These medications are administered in pill form. Studies show they can help strengthen communication between brain cells, which improves symptoms like memory loss and slows down mental decline.

Medicare can cover cholinesterase inhibitors and memantine if they are prescribed by a doctor. Medicare has not announced yet whether aducanumab will be covered (though those with Medicare Part D and Medicare Advantage can probably get help with costs), and a decision on coverage for lecanemab is probably several years away.


Status of Clinical Trials of Lecanemab

Lecanemab is currently in the third stage of trials, and, unfortunately, enrollment is full so there are no longer openings to participate. The Phase 3 study has 1,795 participants taking either the experimental drug or a placebo. Biogen has announced that phase 3 for lecanemab should end in September 2022.

During Phase 2, lecanemab was tested for safety and effectiveness by giving 856 people with mild Alzheimer’s either the drug or a placebo. Researchers saw a reduction of amyloid-beta in the brains of those who took lecanemab, as well as a slower progression of the disease.


When Will Lecanemab Become Available?

The phase 3 trial for lecanemab, with 1,795 people with mild Alzheimer’s taking either the drug or a placebo, is expected to conclude in September 2022. FDA approval requires a thorough review of the data, and that process usually takes between 6 months and a year. The bottom line is that the soonest lecanemab would be made available is probably 2023.

There was a promising development for lecanemab in June 2021, when the Food and Drug Administration granted it the “breakthrough therapy” designation. The FDA considers breakthrough therapies to have shown significant progress, or demonstrated they can help a significant number of people with an important illness. Earning breakthrough therapy status means the process of reviewing the drugs can be sped up.