Eli Lilly says new Alzheimer's drug donanemab slows early stages of disease by 35%

An Alzheimer's drug developed by Eli Lilly slowed cognitive and functional decline for people with early stages of the disease, a study that could lead to a new commercially available drug for the mind-robbing disease, the drug company said Wednesday.

Lilly said people on the experimental drug donanemab slowed decline by 35% compared to a placebo group based on a measure of daily activities such as driving, managing finances and talking about current events.

Lilly said it will submit an application by the end of June to the Food and Drug Administration seeking approval to market the amyloid plaque-busting drug.

"We hope that this is an exciting day for patients and their families," said Dawn Brooks, Lilly's global development leader for donanemab.

In January, the FDA rejected Lilly's attempt to get accelerated approval for donanemab because the agency said the midstage study did not include enough people over at least 12 months.

If the new late-stage study that enrolled more than 1,700 people is enough to warrant FDA approval, it would be the third amyloid-targeting Alzheimer's drug to gain approval.

In January, Eisai and Biogen received FDA approval to sell Leqembi for patients in the early stages of Alzheimer's disease. In 2021, Biogen's Aduhelm was the first to gain approval based on studies that delivered mixed results − an approval that prompted investigations from two U.S. House committees.

What did Lilly's new donanemab study find?

The Trailblazer 2 study found the drug slowed decline by 35% compared to the placebo based on the integrated Alzheimer's disease rating scale, which measures cognition and daily living activities.

Lilly also reported 47% of study participants on donanemab had no decline compared to 29% on placebo. Lilly said 52% completed their donanemab treatment within a year and 72% within 18 months.

Brooks said participants on the drug were allowed to switch to the placebo if the drug cleared all amyloid plaque before the end of the trial.

"Over half of the participants in the donanemab treatment (group) were able to complete the course of treatment in 12 months," Brooks said.

What were the side effects?

Drugs that target and clear amyloid can cause swelling or small bleeds in the brain. These are known as amyloid-related imaging abnormalities, or ARIA, detected by an MRI scan that patients must undergo.

Lilly said 24% of people on the drug had signs of brain swelling, known as ARIA-E, though most did not notice any symptoms. Tiny brain bleeds, known as ARIA-H, were detected in just over 31% on the drug compared to nearly 14% in the placebo group.

Two participants died as a result of ARIA, and a third person died after experiencing ARIA.

What's next for Alzheimer's drugs?

Donanemab, Leqembi and Aduhelm are part of a pipeline of treatments based on a decades-old theory that Alzheimer's disease is triggered by amyloid that accumulates in patients' brains and can be slowed by drugs that remove the buildup of this protein.

Both Leqembi and Biogen's Aduhelm received accelerated approval to get the drugs to market. The Aduhelm approval was controversial and prompted a probe from two U.S. House committees that found the FDA sidestepped outside experts who said trials failed to prove the clinical benefit of the drug.

Following Aduhelm's approval, the Centers for Medicare and Medicaid Services said it would pay for such drugs that received FDA accelerated approval only in clinical trials.

With more than 6 million Americans afflicted with the memory-scuttling disease, advocates are pushing centers to pay for these new drug treatments outside of clinical trials.

Maria Carrillo, Alzheimer's Association chief science officer, said the latest donanebab results are "the strongest Phase 3 data for an Alzheimer's treatment to date."

"The progress we've seen in this class of treatments, as well as the diversification of potential new therapies over the past few years, provides hope to those impacted by this devastating disease," she said. "Yet, Medicare stubbornly continues to block access for the people who could benefit."

Ken Alltucker is on Twitter as @kalltucker or can be emailed at alltuck@usatoday.com.

What Alzheimer's treatments are available?

In January, Eisai and Biogen received FDA approval to sell Leqembi for patients in early stages of Alzheimer's disease. In the Phase 3 clinical trials, the drug reduced cognitive decline by 27%,  but side effects included brain swelling and bleeding.