Long-term treatment (up to 36 months) with lecanemab continued to produce benefits for patients with early Alzheimer’s disease (AD), especially those who got the earliest starts on this anti-amyloid treatment, according to a study issued by Alzheimer’s and Dementia.Why It’s Relevant
Two previous randomized controlled trials showed that lecanemab can reduce amyloid levels and slow clinical decline over 18 months while being generally well-tolerated. This open-label extension study, funded by lecanemab drugmakers Eisai and Biogen, shows that patients continue benefit in the longer term without any indication of new safety concerns.
By the Numbers
- Participants included adults (ages 50 to 90) with early AD and confirmed amyloid pathology; 898 had received 18 months of lecanemab in a prior study while 718 had received placebo and then converted to lecanemab for this study.
- Lecanemab continued to suppress amyloid plaque levels and slow clinical decline on multiple measures of cognition, function, and quality of life for individuals taking it for months 19 to 36.
- The group that switched from placebo did not catch up to the early-start group in their scores on the Clinical Dementia Rating–Sum of Boxes scale, reflecting the importance of prompt treatment with lecanemab, the researchers wrote.
- The cumulative rate of adverse events continued to rise with longer lecanemab exposure, including the occurrence of potentially serious or life-threatening brain bleeding and swelling—though the data continued to suggest that bleeding and swelling were more likely to occur within the first six months of treatment.
The Other Side
As an open-label study, there was no longer any control group with which to compare lecanemab’s efficacy and safety.
What's Next
The long-term extension study will continue collecting patient data through 48 months—stay tuned for more findings.
The long-term extension study will continue collecting patient data through 48 months—stay tuned for more findings.
Related Info
Source
Christopher H. van Dyck, et al. Long-term safety and efficacy of lecanemab in early Alzheimer’s disease: results from the clarity AD open-label extension study. Alzheimer’s & Dementia. Published December 7, 2025. https://doi.org/10.1002/alz.70905
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