Eisai study reveals that patients on Alzheimer's drug Leqembi experience benefits over three years.

• The Alzheimer's drug Leqembi slowed disease progression in patients over three years, indicating the importance of long-term treatment.
• According to new data presented by Japanese drugmaker Eisai at a medical conference, the drug has shown promising results in treating Alzheimer's disease.
• The study results on Leqembi, which Eisai shares with Biogen, showed that the health of Alzheimer's patients who stop taking the therapy worsens.

New data from Japanese drugmaker Eisai shows that the breakthrough Alzheimer's drug Leqembi slowed disease progression in patients over three years, highlighting the importance of long-term treatment.

Eisai's study on Leqembi found that Alzheimer's disease worsens in patients who stop treatment. However, rates of adverse side effects associated with Leqembi, including brain bleeding and swelling, decreased after six months of treatment, according to Dr. Lynn Kramer, Eisai's chief clinical officer of deep human biology learning.

The decline is crucial: The brain side effects have raised concerns among some doctors and are the primary reason the European drug regulator rejected Leqembi last week.

The 24-month efficacy and safety data on Leqembi, which has faced challenges in its U.S. rollout since gaining regulatory approval last summer due to diagnostic test requirements and brain scans, was released by Eisai in November.

On Tuesday at the Alzheimer's Association International Conference in Philadelphia, Eisai presented the initial findings on the potential future of Alzheimer's patients' treatment with therapies such as Leqembi, which is currently administered twice a month through an infusion.

The drug Leqembi is a monoclonal antibody that targets toxic plaques in the brain called amyloid, a hallmark of Alzheimer's, to slow the progression of the disease during its early stages. Additionally, Leqembi works by clearing protofibrils, the building blocks of amyloid plaque.

Early and sustained treatment is crucial for individuals with a difficult-to-treat brain disorder, even after a drug eliminates amyloid plaque.

Kramer stated that maintaining cognition and functionality longer requires continuing treatment.

"Starting early with Leqembi can provide years of benefits, although it is not a cure," said Leqembi.

Eisai believes that patients can eventually switch to a maintenance dose of Leqembi after about 18 to 24 months of treatment, which could be more convenient and less frequent over the long term.

Leqembi, a drug developed by Eisai and Biogen, is being sought for regulatory approval for a monthly infusion, with a decision expected in January. Additionally, the drugmakers aim to bring an injectable form of Leqembi to the market, allowing patients to take it at home once a week.

According to Kramer, those two things will revolutionize the medical system, simplifying the process for patients and making it more efficient.

Almost 7 million Americans suffer from Alzheimer's, the fifth-leading cause of death for adults aged 65 and above, according to the Alzheimer's Association. The number of Alzheimer's patients in the U.S. is projected to increase to nearly 13 million by 2050.

Long-term study details

The findings of the research on Leqembi participants in mid-stage and late-stage trials have been analyzed.

A 36-month trial known as Clarity AD evaluated three distinct patient groups.

In the study, one group of participants received Leqembi for three years, while another group received a placebo for 18 months before switching to Eisai's drug for the same duration. Additionally, Eisai observed a group of patients who did not receive any treatment over three years.

According to an Eisai presentation, patients who began taking Leqembi early experienced a slower rate of cognitive decline over three years compared to the other two groups.

Kramer found that the difference in cognitive decline between the "early start" Leqembi group and patients who did not receive anything throughout the study period grew larger between 18 and 36 months.

"Early detection of the disease is crucial, as interrupting its natural progression can have a more significant impact," he stated.

Patients who initially received a placebo experienced a slower rate of cognitive decline after switching to Leqembi at 18 months, but their Alzheimer's disease was still worse than the group that began Leqembi earlier at the 36-month mark.

The trial's sub-study examined patients with low levels of tau protein, a marker of Alzheimer's severity, and found that they were at the earlier stages of the disease.

According to the presentation, 59% of people with no or very low tau levels who were on Leqembi for three years did not experience any progression of their Alzheimer's disease. However, a little over half of that patient population saw their condition improve.

An alternative version of the sentence could be: A phase two trial, known as Study 201, focused on patients who temporarily paused their treatment with Leqembi.

For 18 months, one group of participants received Leqembi while another group received a placebo. After a two-year gap, all patients began treatment with Leqembi for another 18 months.

The positive impact of Leqembi on a patient's disease persisted even after they discontinued treatment, as per the presentation.

Eisai stated in a release that the rate of cognitive decline in patients who stopped taking Leqembi returned to the rate of those who took a placebo during the gap period, indicating that the disease continues to progress even when amyloid plaque is removed.

Kramer stated that stopping would result in worsening of the concept.