LEQEMBI LEADER Study: Real-World Data at AAIC 2026
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Eisai and Biogen's real-world LEADER study of LEQEMBI (lecanemab) offers fresh evidence on early Alzheimer's care. Presented at AAIC 2026 on July 14, the interim data show most treated patients stayed stable or improved over about 17 months. Eisai, based in Tokyo, leads the program with deep ties across the Asia-Pacific region.
Key Takeaways
Nearly 83% of early Alzheimer's patients stayed stable (75.9%) or improved (6.6%) on LEQEMBI.
The average treatment ran about 17 months, or roughly 520 days across 26 doses.
Results were consistent across sex, race, ethnicity, and APOE genotype.
LEQEMBI (lecanemab) comes from Tokyo-based Eisai, developed with Biogen.
What did the LEADER study find?
Eisai and Biogen said nearly 83% of enrolled early Alzheimer's patients stayed stable or improved on LEQEMBI. In detail, 75.9% remained stable and 6.6% improved. The average follow-up was 17 months. The results held across sex, race, ethnicity, and APOE genotype, per the companies' LEADER study announcement.
The data came from routine clinical care rather than a controlled trial, a real-world perspective that matters to physicians weighing the long-term value of continued treatment.
How was the LEADER study designed?
LEADER is a three-year, multicenter, retrospective real-world study. It draws on chart and electronic medical record data from 13 US sites. This interim analysis covered 432 early Alzheimer's patients. Each had received at least seven LEQEMBI infusions as of May 2026.
At baseline, the mean age was 74 years, and 55.8% were women. About 63.9% had mild cognitive impairment due to Alzheimer's, while the other 36.1% had mild Alzheimer's dementia. The mean treatment ran 520 days across 26 doses.
How does LEQEMBI work?
LEQEMBI (lecanemab) is an anti-amyloid antibody that clears amyloid plaque and toxic protofibrils from the brain, an action intended to slow the loss of memory and daily function. The drug treats early Alzheimer's, which spans mild cognitive impairment and mild dementia.
Why does the APAC angle matter?
Eisai is headquartered in Tokyo and leads the lecanemab program. The pivotal Clarity AD trial enrolled sites across Asia, including Japan, China, South Korea, Singapore, and Australia. Lecanemab has since won approval in several markets, including Japan. New real-world data feed into how Asia-Pacific doctors and payers judge its long-term value, a theme we track in China's NMPA and FDA approval pathways.
What the pivotal Clarity AD trial showed
Clarity AD was a global Phase 3 study in 1,795 people with early Alzheimer's. Patients received 10 mg/kg of lecanemab every two weeks, or placebo, for 18 months. The drug met its main goal on the CDR-SB scale, a measure of dementia severity, as recorded in the Clarity AD registry entry (NCT03887455). The full results were published in the New England Journal of Medicine in 2023.
What remains unproven?
The LEADER analysis is interim and retrospective. It has no placebo group, so it cannot prove cause and effect. Amyloid-related imaging abnormalities remain a known safety risk with this drug class. Longer follow-up will test whether early gains hold and how the drug performs across diverse Asia-Pacific populations.
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Frequently Asked Questions
What did the LEQEMBI LEADER study find?
In the real-world LEADER study, nearly 83% of early Alzheimer's patients stayed stable (75.9%) or improved (6.6%) on LEQEMBI over an average of 17 months. Results held across sex, race, ethnicity, and APOE genotype.
How is LEQEMBI (lecanemab) connected to the Asia-Pacific region?
LEQEMBI is led by Tokyo-based Eisai with Biogen. The pivotal Clarity AD trial ran across Asian sites, including Japan, China, South Korea, Singapore, and Australia, and lecanemab is approved in markets including Japan.
How does LEQEMBI treat early Alzheimer's disease?
LEQEMBI (lecanemab) is an anti-amyloid antibody. It clears amyloid plaque and toxic protofibrils from the brain, which aims to slow the loss of memory and daily function in early Alzheimer's disease.
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