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FDA To Delay Decision on New Alzheimer’s Drug Candidate

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Drugmaker Eli Lilly and Company (Lilly) has announced that their candidate amyloid-targeting drug for Alzheimer’s disease (AD), donanemab, will be further scrutinized by a US Food and Drug Administration (FDA) expert panel.

The drug, previously expected to be approved by the FDA this month, will instead be subject to review in light of safety results in donanemab-treated patients.

Risks of adverse events

“The FDA has decided to delay their licensing decision until an Advisory Committee of experts can determine whether the risks are justified by the benefits of the drug,” explained Professor Robert Howard, professor of old age psychiatry at University College London, who was not involved in the study.

“This delay in granting a US license is a major blow for Lilly and their amyloid antibody donanemab and is based on concerns about the brain swelling and bleeding seen with the drug.”

A similar drug – lecanemab – gained traditional approval by the FDA for AD in 2023. Both drugs work by targeting amyloid plaques in the brain – a key characteristic of AD – and carry risks of brain swelling and bleeding side effects.

However, data suggests donanemab carries twice the risk of these adverse events compared to lecanemab, prompting the FDA’s expert advisory committee meeting.

“The balance between the very modest benefits of the amyloid antibody treatments for Alzheimer’s disease and the risks that they carry is under ever closer scrutiny as the gap between the hype and reality around these drugs narrows,” Howard added.

FDA to address questions in advisory committee meeting

The data being reviewed comes from the Phase 3 TRAILBLAZER-ALZ 2 trial, published in the Journal of the American Medical Association. The study evaluated the safety and efficacy of donanemab, an antibody designed to clear amyloid plaques in the brain, in patients with early AD.

The trial’s participants were aged 60–85 with confirmed presence of tau pathology – the accumulation of misfolded tau proteins in the brain – which is another AD characteristic.

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Data from the randomized, placebo-controlled trial suggested donanemab modestly slowed cognitive decline, which continued even after patients stopped receiving the drug.

The review will enable the FDA to understand more about the trial’s dosing regimen and inclusion of patients based on tau levels. The limited-duration dosing schedule allowed patients to stop treatment when they reached a certain level of amyloid plaque.

The date for the advisory panel’s meeting, overseen by the Peripheral and Central Nervous System Drugs Advisory Committee (PCNS), has not yet been set. Expected action from the FDA is therefore expected to come after the first quarter of 2024.

"We are confident in donanemab's potential to offer very meaningful benefits to people with early symptomatic Alzheimer's disease,” explained Anne White, executive vice president of Lilly and president of Lilly Neuroscience, in a press release. “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. We will work with the FDA and the stakeholders in the community to make that presentation and answer all questions.”