Health

Study: Antibody Treatment Effective Against Early-Stage Alzheimer's

AUG 1 2025·Updated AUG 2 2025

Story

Above: Eisai Co. signage at the company's headquarters in Tokyo, Japan, on Feb. 3, 2023. Image credit: Akio Kon/Bloomberg/Getty Images

The Facts

Japanese pharmaceutical company Eisai and U.S. biotechnology firm Biogen presented data at the 2025 Alzheimer's Association International Conference, showing the effectiveness of lecanemab for early-stage Alzheimer's disease.
The Pharma Letter
Neurology Live
Lecanemab is a monoclonal antibody that targets soluble and insoluble forms of amyloid-beta in the brain. Amyloid-beta proteins can clump together to form plaques, a hallmark of Alzheimer's, which can disrupt brain function.
BMJ
The Telegraph
Eisai
The companies showcased the results of a Phase 3 study evaluating the effects of bi-weekly treatment with 10 mg/kg of lecanemab. The study involved 1,795 patients, 95% of whom continued to participate after the 18-month core study, with 478 receiving treatment for four years.
Eisai
The study found that patients who received over three years of lecanemab treatment experienced a 1.01 point reduction in cognitive decline compared to the expected natural progression of the disease, with a 1.75 point reduction after four years of treatment.
Biogen
Pharma Times
Among a low-tau subgroup of patients treated with lecanemab for four years or longer, the study reported that 69% showed improvement or no cognitive decline, while 56% showed improvement relative to the baseline.
Eisai
The trials also demonstrated a "consistent safety profile," with no new safety concerns found among those treated for more than four years, and decreasing rates of amyloid-related imaging abnormalities after 12 months, before remaining consistent thereafter.
Biogen

Sources Split

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The Spin

Narrative A

These results show that Alzheimer's patients can maintain cognitive function for years longer than previously thought possible with the proper treatment. The data show that early intervention clearly works, with some patients showing improvement rather than decline, validating investment in amyloid-targeting therapies and supporting broader access to these treatments.

The Telegraph

Narrative B

While the data appear promising, the study lacks a proper control group and requires further testing to confirm lecanemab's long-term safety and effectiveness. This is critical for informing healthcare providers about guidelines, costs and patient access — especially given the complexities associated with Alzheimer's diagnosis and treatment.