Eli Lilly's Alzheimer's drug donanemab — sold as Kisunla — now has three years of evidence showing it can slow cognitive decline even after patients stop taking it. Data presented at the AD/PD 2026 conference in Copenhagen and the CTAD meeting in late 2025 confirm what researchers hoped: clearing amyloid plaques from the brain produces durable, growing benefits.
For the 55 million people worldwide living with dementia, this is the strongest signal yet that Alzheimer's can be meaningfully slowed — and possibly, in early stages, partially reversed.
- Drug: Donanemab-azbt (brand name Kisunla), by Eli Lilly
- Approved: FDA full approval July 2024; EU approval October 2025
- What it does: Clears amyloid plaques from the brain to slow cognitive decline
- Key finding: Benefits sustained for 3 years, even after treatment stops
- Cost: ~$32,000/year in the US (treatment can end once plaques clear)
What the New Data Shows
The TRAILBLAZER-ALZ 2 long-term extension study tracked patients for three years after their initial treatment. The results were striking:
Patients who completed donanemab treatment within 12 months continued to show cognitive and functional benefits for two additional years without further infusions. Compared to untreated individuals, treated patients showed a 1.2-point reduction in decline on the CDR-SB scale — the standard measure of Alzheimer's progression — at the three-year mark.
Critically, amyloid plaques reaccumulated at a slow rate of just 2.4 Centiloids per year after treatment ended. This means the "clean slate" donanemab creates in the brain stays relatively clean for years — a finding that distinguishes it from treatments requiring indefinite dosing.
How Donanemab Works — and Why It's Different
Donanemab targets N3pG amyloid, a specific modified form of the protein that makes up Alzheimer's plaques. Unlike older approaches that targeted amyloid broadly (and mostly failed), donanemab goes after the plaques themselves.
The most significant difference from its main competitor, lecanemab (Leqembi): donanemab is designed as a finite treatment. Patients receive monthly IV infusions until brain scans confirm their plaques have cleared — often within 6 to 12 months — then stop. Lecanemab, by contrast, currently requires ongoing maintenance dosing.
"Patients can stop treatment as early as 6 months once their amyloid plaque is cleared." — Anne White, President of Lilly Neuroscience
Donanemab vs Lecanemab: Head-to-Head
Two drugs now dominate the Alzheimer's treatment landscape. Here's how they compare:
| Feature | Donanemab (Kisunla) | Lecanemab (Leqembi) |
|---|---|---|
| Maker | Eli Lilly | Eisai / Biogen |
| FDA Approval | July 2024 | January 2023 |
| Target | Established amyloid plaques (N3pG) | Soluble amyloid protofibrils |
| Efficacy | 35% slowing of decline | 27-30% slowing of decline |
| Treatment Duration | Finite (6-18 months typical) | Ongoing maintenance |
| Administration | Monthly IV infusion | Biweekly IV or subcutaneous |
| Annual Cost (US) | ~$32,000 | ~$26,500 |
| ARIA-E Risk | 14% (with updated dosing) | ~13% |
| EU Approved | Yes (Oct 2025) | Yes |
The Safety Question
Both anti-amyloid drugs carry the risk of ARIA — amyloid-related imaging abnormalities that can cause brain swelling or microbleeds. In donanemab's original trial, ARIA-E occurred in 24% of patients.
However, a modified titration dosing schedule approved by the FDA in July 2025 cut that risk to 14% — a 41% relative reduction. The three-year extension study found no new safety signals beyond what was already known.
- First finite-duration Alzheimer's treatment (can stop once plaques clear)
- Benefits grow over 3 years even after stopping
- 84% average plaque clearance
- Updated dosing significantly reduces brain swelling risk
- EU and US approved with strong regulatory backing
- $32,000/year cost (though finite treatment lowers total spend)
- 14% risk of brain swelling even with updated dosing
- Requires specialized PET imaging not available everywhere
- Only works in early-stage disease (mild cognitive impairment or mild dementia)
- NICE initially deemed it not cost-effective for UK's NHS
The Road to Cognitive Recovery
Researchers are now shifting focus from "slowing decline" to actual cognitive recovery — reversing some of the damage Alzheimer's causes. In the TRAILBLAZER-ALZ 2 trial, 47% of patients on donanemab showed no clinical progression at one year, compared to 29% on placebo.
The next frontier is combination therapy. Eli Lilly and other companies are testing donanemab alongside tau-targeting therapies, which could address the second hallmark protein in Alzheimer's. If amyloid clearance stops new damage and tau clearance repairs existing damage, genuine cognitive recovery moves from theory to reality.
What Comes Next
Eli Lilly is scaling manufacturing at new facilities in Ireland and Germany to meet global demand. The company's 2026 revenue guidance of $80-83 billion reflects confidence in Kisunla as a growth driver.
Meanwhile, remternetug — Lilly's next-generation antibody that can be self-injected subcutaneously instead of requiring IV infusions — is in Phase 3 trials with results expected late 2026. If approved, it could dramatically simplify treatment access.
For the estimated 6.9 million Americans and 55 million people globally living with Alzheimer's, the message from the latest data is cautiously revolutionary: we cannot cure this disease yet, but for the first time, we can measurably slow it, stop treatment, and watch the benefits endure. The era of therapeutic nihilism in Alzheimer's is over.
