Eli Lilly’s Kisunla is now FDA approved for treating patients in the early stages of Alzheimer’s disease. In addition to slowing cognitive decline and disease progression, clinical trial results showed that amyloid beta plaques were reduced to the point where some patients could stop taking the infused therapy.

By Frank VinluanEli Lilly Alzheimer’s disease drug has received its long-awaited FDA approval, bringing patients a treatment that works similarly to an Eisai medication for the neurodegenerative disorder but with dosing advantages that patients might prefer.
The Tuesday regulatory decision comes less than a month after an FDA advisory committee voted unanimously that the benefits of the Lilly drug in slowing cognitive decline outweigh its safety risks. The approval covers the treatment of Alzheimer’s patients with mild cognitive impairment or mild dementia, the same population that was evaluated in clinical trials. Known in development as donanemab, Lilly will market its new Alzheimer’s medication under the brand name Kisunla.
One of the hallmark characteristics of Alzheimer’s is the aggregation of two types of protein in the brain: amyloid beta and tau. Kisunla is an antibody designed to target and reduce plaques of amyloid beta protein in the brain. Lilly supported its FDA submission with data from a placebo-controlled Phase 3 study that enrolled 1,736 patients with confirmed amyloid plaques and mild cognitive impairment or mild dementia due to Alzheimer’s. The main study goal was to measure the change in score according to a rating scale used to assess Alzheimer’s patients.
Over 18 months, the study drug arm evaluated two groups of patients: one with low-to-medium levels of tau and an overall population of patients with high levels of that protein. Results showed that the group with low-to-medium tau achieved a statistically significant 35% slowing of decline compared to placebo, as measured by a rating scale used to assess cognitive and functional ability in Alzheimer’s patients. In the overall study population, the slowing of decline was 22%. These results were also statistically significant. Furthermore, data from the study showed that Kisunla-treated patients had a 39% lower risk of progressing to the next stage of disease compared to those who received a placebo. The study results were published last year in the journal JAMA Network.
One of the secondary goals of the clinical trial was to measure clearance of amyloid from the brain. In the overall study population, medical imaging of brains showed treatment with Kisunla reduced amyloid plaques from baseline by an average of 61% at six months, by 80% at 12 months, and by 84% at 18 months. Patients confirmed to have reached specified levels of amyloid clearance were permitted to stop taking the drug and receive a placebo for the remainder of the trial. This unusual trial design played a role in regulatory setbacks that delayed an FDA decision for the drug.
In early 2023, the FDA turned down Lilly’s application, asking for more data from patients who took the drug for at least 12 months. At the time, Lilly did not have those data because the amyloid clearance achieved by Kisunla meant many patients were moving off of the study drug before hitting the 12-month mark. Lilly eventually gathered the requested data and resubmitted its application last summer. But this past March, the FDA told Lilly it would convene an advisory panel to weigh in on the drug, a move that was consistent with the reviews of Aduhelm and Leqembi, the antibody drugs from partners Biogen and Eisai that had each received accelerated FDA approval. While this additional layer of review further delayed the regulatory decision, the approval was welcomed by the Alzheimer’s community.
“This milestone will not only catalyze the next generation of therapies, but also reframe how we deliver treatments,” Howard Fillit, co-founder and chief science officer of the Alzheimer’s Drug Discovery Foundation, said in a prepared statement. “It’s promising to see that some patients essentially enter remission, where they achieve full amyloid clearance with no resurgence in substantial plaque buildup for several years to follow.”
Kisunla’s label carries a black box warning that alerts clinicians and patients about the risk of serious and potentially life-threatening brain bleeds and inflammation. The label also cautions that people who carry the ApoE 4 gene have a higher risk of developing these complications. These risks are associated with the class of antibody drugs for Alzheimer’s. The black box warning for Leqembi is similar.
While Biogen has stopped selling Aduhelm, Eisai leads the commercialization of Leqembi and is continuing to market that product. Leqembi, which received full FDA approval last July, is administered as an hourlong intravenous infusion every two weeks. By contrast, Lilly’s Kisunla is given as a 30-minute infusion administered once monthly.
Leqembi carries an annual price of $26,500, but comparing pricing with the Kisunla is tricky. Lilly has priced its new Alzheimer’s drug at $695.65 per vial, and like Leqembi, the number of vials needed is calculated according to a patient’s weight. But complicating the pricing picture is the dosing schedule. Unlike Leqembi, which patients will take indefinitely or until adverse effects warrant stopping treatment, the Lilly drug’s label permits stopping treatment after medical imaging shows removal of amyloid plaques — just as it did in its Phase 3 clinical trial. That means for some patients, a shorter duration of treatment is possible. Less frequent dosing and the possibility of stopping dosing entirely reduces a patient’s exposure to the therapy, which in turn lowers the safety risk to the patient.
Lilly provided several examples of treatment scenarios for its new drug. A patient needing 12 months of treatment with Kisunla would require 13 infusions for a total cost of $32,000, making it more expensive than one year of Leqembi. Six months of treatment would require six infusions totaling $12,522, while 18 months of treatment would require 19 doses at a total cost of $48,696. The out-of-pocket cost to patients will depend on the duration of treatment and the patient’s insurance. A Centers for Medicare and Medicaid Services coverage determination established for Aduhelm in 2022 covers the entire class of amyloid plaque-busting antibody drugs, including Kisunla.
Photo: Craig F. Walker/The Boston Globe, via Getty Images