What you need to know about Leqembi

Last year, Eisai and Biogen reported that their new, experimental Alzheimer's drug, lecanemab, which has been branded as Leqembi, slowed cognitive and functional decline by 27% compared to a placebo over an 18-month clinical trial. The drug works by reducing abnormal clumps of beta amyloid, proteins that are typically a sign of Alzheimer's disease.

In the trial, 1,795 patients with mild cognitive impairment caused by Alzheimer's disease or early-stage Alzheimer's received either Leqembi or a placebo. At the end, the patients were tested using the Clinical Dementia Rating sum of boxes (CDR-SB), which measures six domains of cognitive decline with a score ranging from zero to 18, with a higher score meaning more severe cognitive decline.

During the 18 months of the study, patients who received lecanemab performed .45 points better on the CDR-SB than those receiving a placebo, results that the drugmakers said hit the threshold of statistical significance.

Around 21% of the participants in the study experienced brain swelling or brain bleeding that was visible on PET scans after taking Leqembi, and less than 3% of those patients had symptomatic cases. According to the companies, those side effects were within expectations.

In July, FDA granted full approval to Leqembi. According to Teresa Buracchio, acting director of FDA's office of neuroscience, Leqembi's approval "is the first verification that a drug targeting the underlying disease process of Alzheimer's disease has shown clinical benefit in this devastating disease."

Following the approval, CMS Administrator Chiquita Brooks-LaSure said CMS "will cover this medication broadly while continuing to gather data that will help us understand how the drug works."

Major health systems plan to offer Leqembi to patients soon

So far, several major health systems, including Mayo Clinic, Northwestern Memorial, and Cedars-Sinai, have said they plan to offer Leqembi to patients in the next few months after they work out logistics, such as payment/administrative policies and how to monitor and assess patients on the drug.

"The patients are lining up," said James Galvin, who leads the Alzheimer's research program at the University of Miami Miller School of Medicine. "They want to be treated, but it's difficult to rush right into it."

Before patients can be prescribed Leqembi, they must be screened and undergo several tests to ensure they are eligible for the treatment. Patients will be screened with cognitive tests to determine whether their Alzheimer's is still early enough to be treated. They will also undergo genetic tests to help understand their potential risks of side effects, as well as either a brain scan or spinal fluid test to confirm the presence of amyloid.

According to Galvin, the amyloid testing may lead to issues since hospitals and patients typically prefer amyloid PET scans, which are less invasive but have been limited to patients in clinical trials. Medicare currently pays for the spinal fluid test.

During treatment, providers will also have to carefully monitor patients for any brain swelling or bleedings. Patients will likely need to undergo several MRIs during treatment to watch for these potential side effects.

According to Sanjeev Vaishnavi, a clinal neurologist at Penn Memory Center, which plans to roll out Leqembi this month, the logistics of getting patients screened, tested, and on the drug will likely be challenging. If demand for Leqembi is high, some patients could end up waiting years for treatment, and by that time, they may no longer benefit from the drug.

"I think the concern is, how can we deliver appropriate care to the right individuals in a timely manner?" Vaishnavi said, adding that he's worried patients will end up "stuck in a morass of bureaucracy."

However, even with these potential issues, Vaishnavi said "it's an exciting time" for Alzheimer's treatments.

Jason Karlawish, co-director at the Penn Memory Center, expressed a similar sentiment, saying, "I'd much rather be in this place than where things were two or three years ago. This is what we've been waiting for for decades."

According to Eisai and Biogen, "[m]any physicians have been prescribing Leqembi and uptake continues to progress as anticipated." In an investor call, Eisai said it expects 10,000 patients to receive the drug by March 2024, which could increase to 100,000 patients by 2026. (Steenhuysen/Beasley, Reuters, 8/7; Scott, Vox, 7/7)

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