Eli Lilly says FDA delays approval of Alzheimer's drug in surprise move

Eli Lilly said Friday that the Food and Drug Administration has pushed back its approval decision deadline for the drugmaker's experimental Alzheimer's treatment donanemab in a surprise move.

The agency plans to call a last-minute meeting of its outside advisors to further review the treatment's safety and efficacy in a late-stage trial, Eli Lilly said. The FDA has not disclosed the date of that meeting, so a potential approval would likely come after this month.

The FDA was expected to decide whether to greenlight the medicine by the end of the first quarter. That deadline was already delayed from an expected approval last year. 

Eli Lilly's drug significantly slowed Alzheimer's progression in a late-stage trial. But the treatment, along with similar drugs, carries safety concerns related to brain swelling and bleeding.

The agency's decision to call for an advisory meeting reflects the high stakes of developing treatments for Alzheimer's. The condition affects more than six million Americans and currently has no cure, leaving patients who have it with few effective care options. 

It's another setback for Eli Lilly, which is racing to compete with Biogen and Eisai. Their treatment Leqembi won approval last year, becoming the first medicine proven to slow the progression of Alzheimer's in people at the early stages of the memory-robbing disease. 

Both Leqembi and Eli Lilly's drug are monoclonal antibodies that target buildups of a protein in the brain called amyloid plaque, which is considered a hallmark of the disease.

Eli Lilly called the delay "unexpected," but said it is confident in donanemab's "potential to offer very meaningful benefits to people with early symptomatic Alzheimer's disease," according to a release. 

"We will work with the FDA and the stakeholders in the community to make that presentation and answer all questions," said Anne White, president of neuroscience at Eli Lilly, in a release.

Eli Lilly noted that while it is unusual for the FDA to hold an advisory panel meeting after a set action date, the agency has convened similar meetings for two other amyloid plague-targeting therapies that it previously approved.

The FDA often turns to an advisory panel for advice on whether an unapproved product is safe and effective.

The agency usually follows the recommendations of its advisors, but isn't required to. In 2021, the FDA approved an earlier, ill-fated Alzheimer's drug called Aduhelm from Biogen and Eisai, despite a negative recommendation from the agency's advisory panel.

The FDA will examine an 18-month phase three trial, which followed more than 1,700 patients in the early stages of Alzheimer's who had a confirmed presence of amyloid plaque. The agency is interested in understanding the safety results and how the trial's "unique" design affected efficacy.

Eli Lilly's study allowed patients to stop taking the drug once the amyloid plaques were shown to be cleared from the brain. Alzheimer's drugs, including Leqembi, don't have designated stopping points for patients.

Eli Lilly's drug showed positive results in that trial. Patients who received the drug demonstrated a 35% slower decline in memory, thinking and their ability to perform daily activities compared with those who did not receive the treatment, data shows.

But 37% of people who took donanemab had brain swelling or bleeding, including three who died, according to the trial. That compares with around 15% of people who received a placebo. 

Those side effects have also been observed in Leqembi.