Alzheimer's drug that can slow disease gets backing from FDA advisers

A highly anticipated Alzheimer's drug from Eli Lilly received support from federal health advisers on Monday, setting the stage for its likely approval for treating mild dementia caused by the disease.

Food and Drug Administration (FDA) advisers unanimously endorsed the drug donanemab, stating that its benefits in slowing Alzheimer's progression outweigh the risks, which include potential brain swelling and bleeding that will need to be monitored.

"I thought the evidence was very strong in the trial showing the effectiveness of the drug," said Dean Follmann, a statistician from the National Institutes of Health, to the Associated Press.

The FDA is expected to decide on the drug later this year. If approved, donanemab would be the second Alzheimer's drug in the U.S. to slow cognitive decline and memory problems convincingly. Last year, the FDA approved a similar drug, Leqembi, from Japanese drugmaker Eisai.

Debate over the drug's impact

The effectiveness of both drugs amounts to a few months of slowed progression, and experts are divided on whether patients or their families will notice the difference.

Lilly's study of its once-a-month treatment raised questions from FDA reviewers, as patients were grouped based on their levels of a brain protein called tau, which predicts the severity of cognitive decline. This led the FDA to consider whether patients should undergo brain scans for tau before receiving the drug. However, most panelists believed there was sufficient evidence to prescribe the drug broadly without such screening.

"Imposing a requirement for tau imaging is not necessary and would raise serious practical and access concerns to the treatment," said Dr. Thomas Montine of Stanford University, who chaired the panel and summarized its opinion.

Similar results to Leqembi

Lilly’s results were similar to those of Leqembi, with both drugs showing modest cognitive improvement in early-stage Alzheimer’s patients. In a 1,700-patient study, Lilly found that patients receiving monthly IV infusions of donanemab declined about 35% more slowly than those on a placebo.

The FDA had been expected to approve donanemab in March but opted to have its panel of neurology experts publicly review the data, leading to an unexpected delay that surprised analysts and investors.

Several unique aspects of Lilly's testing prompted the meeting. One was measuring patients' tau levels and excluding those with very low or no protein levels. Despite this, panelists felt confident that nearly all patients could benefit from the drug, regardless of their tau levels.

Another unique approach was studying patients who stopped the drug when they reached low levels of amyloid, a brain plaque associated with Alzheimer's. Lilly suggested this could reduce side effects and costs, but FDA staff noted there was little data on the optimal time to stop or restart treatment.

Safety concerns and mitigation

Despite these questions, many panelists thought the possibility of stopping doses held promise. 

"It’s a huge cost savings for society, we’re talking about expensive treatment, expensive surveillance," said Dr. Tanya Simuni of Northwestern University. She and other experts noted that patients would need to be tracked and tested to determine if and when they should resume treatment.

The primary safety issue with donanemab was brain swelling and bleeding, a problem common to all amyloid-targeting drugs. Most cases identified in Lilly's trial were mild. Three deaths in the study were linked to the drug, all involving brain swelling or bleeding, with one death caused by a stroke, a complication more frequent among Alzheimer's patients.

The Associated Press contributed to this story. It was reported from Los Angeles.