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May 03, 2023

Eli Lilly says its experimental Alzheimer's drug slows cognitive decline

The company, which will seek FDA approval for donanemab, says it is encouraged by the results of a clinical trial. But it noted the treatment may cause serious side effects

Eli Lilly's experimental drug for Alzheimer's disease effectively reduced cognitive decline in a large clinical trial, the company said Wednesday.

The study found that 47% of Alzheimer's patients that took the drug, named donanemab, did not experience cognitive or functional declines during one year of treatment. That was true of only 29% of the patients who received a placebo.

The drug slows decline by removing amyloid plaque buildup in the brain. Amyloid proteins are considered a hallmark of Alzheimer's disease.

New drugs designed to treat Alzheimer's disease have been criticized over concerns their effectiveness is hard to measure. The U.S. Food and Drug Administration initially rejected Eli Lilly's application for accelerated approval for donanemab, requesting more data. With that data in hand, the company said it plans to seek full FDA approval by the end of June.

The study of more than 1,700 participants found that donanemab slowed clinical decline by 35% compared to the placebo and was associated with 40% less decline in the ability to perform daily tasks. The drug is given as an infusion once per month. 

There were some side effects associated with the drug during the trial, including three deaths. Two of the deaths were caused by brain swelling.

"We are encouraged by the potential clinical benefits that donanemab may provide, although like many effective treatments for debilitating and fatal diseases, there are associated risks that may be serious and life-threatening," said Dr. Mark Mintun, group vice president of Lilly's neuroscience research & development and president of Avid Radiopharmaceuticals.

He said the patients who appear to benefit the most from the drug are those in an early stage of disease progression.

Donanemab is among a class of drugs that has showed a lot of promise in Alzheimer's research, Dr. Daniel Skovronsky, Lilly's chief scientific and medical officer, told CNN. These drugs are able to quickly reduce large amounts of amyloid.

The FDA has approved two other Alzheimer's drugs – both monoclonal antibody treatments – in the last two years. These drugs are not cures, pose health risks, and only temporarily improve symptoms. 

Leqembi, developed by Eisai and Biogen, received accelerated FDA approval in January to be given to Alzheimer's patients with mild dementia. Tests also must show that the patients have brain plaque associated with Alzheimer's. 

Aduhelm, also developed by Biogen, received FDA conditional approval in June 2021. It was the first new Alzheimer's treatment in 20 years, but the FDA was criticized by scientists who said there wasn't enough evidence of its effectiveness. 

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