During the past three years two drugs (Aduhelm and Leqembi) that were designed to slow the progression of Alzheimer’s disease, have been approved.

A verdict by the FDA on a third drug, Eli Lilly’s donanemab, had been scheduled for the end of March. However, efforts by the FDA seeking additional information on its safety will delay the March deadline.
The current delay comes on the heels of Eli Lilly’s attempt to receive Accelerated Approval for the drug last year based on its Phase 2 trial.

A Unique Design

The unique design of the underlying study associated with Eli Lilly’s application allows patients to stop taking donanemab once the amyloid protein has been removed from the brain.

The Advisory Committee

Lilly suggested that it was unusual that the FDA would schedule the advisory committee meeting at this point in the drug’s evaluation. Lilly also stated that a panel’s negative vote may influence the FDA’s review. However, the company recalled that outside advisers were summoned to review Leqembi and Aduhelm yet both drugs were approved.

A Conciliary Word

Howard Fillit, co-founder of Alzheimer’s Drug Discovery Program, offered a conciliary word about the FDA’s review. He said that it is a step in the right direction rather than a setback. He added that it is simply the FDA’s involvement in its due diligence before the drug is distributed to patients.

A Type of Brain Swelling

The agency’s concern is that donanemab, and similar drugs, have been associated with a form of brain swelling. Biogen’s Aduhelm has been taken off the market due to disappointing sales and lack of sufficient effectiveness.

Biogen and Eisai’s Leqembi remains on the market but only 2,000 patients in the United States have received the drug since February 2024. Although Leqembi and donanemab have not been tested against each other, clinical testing showed donanemab to have more of an impact on slowing disease progression.

Encouraging Data

Data from a more recent study, TRAILBLAZER-ALZ2, was reported four months subsequent to the Phase 2 trial with positive results. Patients who took donanemab saw a 35% slower disease progression than patients taking a placebo.