Eli Lilly's Alzheimer's drug delayed by FDA: ‘It was unexpected’

 The U.S. Food and Drug Administration has postponed a decision on Eli Lilly’s potential Alzheimer’s treatment donanemab with an unusual request to have an advisory committee examine the drug. 

On Friday, the FDA announced it wanted to further understand topics related to evaluating the "safety and efficacy of donanemab," including the safety results of donanemab-treated patients. 

Lilly had expected the FDA to decide on donanemab's approval by the end of the month

"We are confident in donanemab's potential to offer very meaningful benefits to people with early symptomatic Alzheimer's disease," Anne White, executive vice president of Eli Lilly and Company, and president of Lilly Neuroscience said in a statement. "It was unexpected to learn the FDA will convene an advisory committee at this stage in the review process, but we look forward to the opportunity to further present the TRAILBLAZER-ALZ 2 results and put donanemab's strong efficacy in the context of safety."

File: Brain scan images (Credit: Brian B. Bettencourt/Toronto Star via Getty Images)

The company said it will work with the FDA and the stakeholders in the community to make that presentation and answer all questions. No date has been set for the advisory committee meeting. 

TRAILBLAZER-ALZ 2 is a late-stage study to evaluate the safety and efficacy of donanemab in participants ages 60-85 years with early symptomatic Alzheimer's disease (MCI or mild dementia due to Alzheimer's disease). 

RELATED: Scientists find signs of Alzheimer's in dolphin brains

The trial enrolled more than 1,700 participants, across eight countries, who were selected based on cognitive assessments and imaging.

The 18-month study, published in the Journal of the American Medical Association (JAMA), showed that patients taking donanemab declined about 22% more slowly in terms of memory and cognitive ability than those who received a dummy infusion. The delay amounted to about four to seven months.

In the study, patients were taken off the drug once their brain plaque reached low levels. Most patients reached that point within a year.

Donanemab, if approved, would follow Eisai’s Leqembi, which was approved last year, and Biogen’s Aduhelm. Biogen announced earlier this year that it would stop selling Aduhelm.

The Lilly drug and Leqembi both treat mild or early cases of dementia caused by the fatal disease. The IV drugs target one of Alzheimer’s culprits, sticky amyloid plaque buildup in the brain.

RELATED: Alzheimer’s drug Leqembi granted full FDA approval and that means Medicare will pay for it

Donanemab, like Leqembi, comes with serious side effects that include brain swelling and bleeding. Those are common to all plaque-targeting drugs and require close monitoring.

About a quarter of donanemab recipients showed evidence of that swelling, and about 20% had microbleeds.

According to the Centers for Diseas Control and Prevention, Alzheimer's disease is the most common type of dementia. It is a progressive disease beginning with mild memory loss and possibly leading to loss of the ability to carry on a conversation and respond to the environment. Alzheimer's disease involves parts of the brain that control thought, memory, and language. 

This story was reported from Los Angeles. The Associated Press contributed.

HealthU.S.