The FDA approved Eli Lilly’s anti-amyloid drug Kisunla (generic name donanemab) on July 2nd. While the drug does not reverse or cure the disease, it may slow its progression in the early stages. In clinical trials, the drug was able to clear out beta-amyloid plaques from patients in the earliest stages of Alzheimer’s—a process associated with a slower rate of cognitive decline. 

Kisunla joins Leqembi as one of two Alzheimer’s monoclonal antibody drugs approved by the FDA in the past year. Leqembi hit the market in July 2023. 

Is Kisunla effective?

To test whether the drug is effective, researchers compared Kisunla to a placebo over the course of 1.5 years. The study used two standardized scales to measure symptoms and disease progression. (Higher scores indicate more cognitive impairment on both scales.) The study participants who received Kisunla had a 22% slower progression on one of the scales and 29% slowing on the other scale. Participants who had higher levels of another Alzheimer’s biomarker called tau in their brains benefited less from the drug. After a year, half of the patients taking the drug were able to stop because the drug had cleared the amyloid in their brain below a minimum threshold.

During the FDA advisory committee hearing in June, Sandra Carlino spoke on behalf of her husband, George, who participated in the donanemab trial.

“Our experience in this trial has been life-changing,” she said. “We understand that his disease may never be cured, but his progression has slowed down [so] immensely that, to the point of a casual observer or acquaintance, they would not know he has this condition.”

This is glowing praise, but with previous drugs of this kind, there has been some debate among doctors as to whether the cognitive benefits are significant enough to make a tangible difference in patients’ day-to-day lives.

How is Kisunla different from Leqembi?

Kisunla and Leqembi target different forms of beta-amyloid. Leqembi targets beta-amyloid before it forms plaques, while donanemab attaches to the plaques themselves. 

Kisunla requires infusions less frequently than Leqembi—monthly instead of biweekly—and comes with stopping instructions. Unlike Leqembi, clinicians can stop treating patients with Kisunla once the levels of beta-amyloid in the brain drop below a minimal level. 

Does Kisunla have side effects?

Kisunla has similar side effects to other anti-amyloid antibody-based drugs. Kisunla may lead to brain swelling or brain bleeding—called amyloid-related imaging abnormalities (ARIA). Carriers of the Alzheimer’s risk gene APOE4 are at a higher risk of these side effects. 

Two in five patients who received the drug during the trials experienced some form of ARIA, and more than three in 10 patients taking the drug experienced brain bleeding. Often, people who develop ARIA don’t have any symptoms. However, the long-term impact of ARIA is unknown. Doctors may temporarily stop treatment until the ARIA resolves itself.