How Alzheimer’s drugs Leqembi and Kisunla treat the cause of dementia

With over 7 million people over the age of 65 dealing with the degenerative disease — and the number expected to almost double by 2050 — Alzheimer’s is the most common form of dementia.

But two new groundbreaking drugs could pull the reigns on the memory impairment and overall brain decline associated with the disease.

While there’s no known cure for Alzheimer’s, both treatments have been shown to slow down dementia from progressing and getting worse when prescribed in early stages.

Leqembi

Leqembi, from the drugmaker Eisai & Biogen, was fully approved by the FDA in July 2023. It’s administered by intravenous infusion, once every two weeks.

Treatment is ongoing, but after 18 months, some patients can often transition to a monthly at-home injections, which were just approved this past summer.

It improves mild cognitive impairment or dementia by clearing amyloid plaques from the brain.

Known as a monoclonal antibody, the medication binds to beta-amyloid, the protein fragment that forms the plaques, a hallmark sign of the disease.

Leqembi also removes protofibrils, another type of protein clump that is thought to be especially harmful to brain cells.

Patients showed improved results from brain scans and thinking tests.

Kisunla

Kisunla, from Eli Lilly, was approved by the FDA in July 2024.

It works similarly to Leqembi, removing amyloid plaques from the brain. It is also administered via IV, but once every four weeks.

It may be slightly more effective than Leqembi: Studies show Kisunla slows cognitive decline by 35%, while Leqembi users saw a 27% improvement. However, these stats are from two different studies — the drugs have yet to be tested head-to-head, so one can’t be said definitively to trump the other.

How much do they cost?

Both drugs are pretty expensive when paid for out of pocket. Leqembi is about $26,500/year, while Kisunla is about $32,000/year.

Fortunately, Medicare covers both at about 80%. Many private insurers require prior authorization.

Leqembi and Kisunla side effects

However, both Leqembi and Kisunla still have potential side effects.

The most significant risk of both is Amyloid-Related Imaging Abnormalities (ARIA), which can include temporary brain swelling or small spots of bleeding.

Symptoms like headache, confusion, dizziness or changes in vision can also occur.

There’s also the risk of side effects related to getting infusions, like fever, chills, nausea or headache.

The IV also goes into a vein in the arm or the back of the hand, and bruising is common.

Despite the possible side effects, these two medications are breakthroughs for early treatment.

“We know these medicines have the greatest potential benefit when people are treated earlier in their disease,” said Anne White, EVP at Eli Lilly and Company, back in a 2024 press release. “Each year, more and more people are at risk for this disease, and we are determined to make life better for them.”