New drug donanemab slows cognitive decline in early Alzheimer’s

The experimental treatment donanemab is now the second antibody drug to slow cognitive decline in people with early stage Alzheimer’s disease, but questions remain about its real-world benefits and safety

By Alice Klein

4 May 2023

Plaques of the protein amyloid build up in the brains of people with Alzheimer’s disease

nobeastsofierce Science/Alamy

A drug called donanemab has been shown to slow cognitive decline by 35 per cent in people with early Alzheimer’s disease. However, there has been a mixed reaction as to how big of an impact this slowed decline will have on a person with Alzheimer’s life and some are concerned over the risk of serious brain swelling and bleeds.

Donanemab is an antibody treatment that is being developed by US pharmaceutical company Lilly. It binds to clumps of protein called amyloid plaques that build up in the brains of people with Alzheimer’s disease. This binding activates an immune response to clear them out.

The drug was evaluated in a clinical trial involving almost 1200 people aged 60 to 85 with early Alzheimer’s disease – defined as mild cognitive impairment and dementia due to the condition – in the US, Canada, UK, Australia, Japan and Europe. The participants received intravenous injections of donanemab or a placebo every two weeks over 18 months.

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At the beginning and end of the trial, the participants were assessed on their cognitive skills and ability to discuss current events, manage their finances and conduct other everyday tasks.

Those taking donanemab had 35 per cent slower decline in their overall scores than those in the placebo group, according to a results summary released by Lilly on 3 May.

“The results of this study are very encouraging,” says Bruce Brew at the University of New South Wales, Australia. “While the full results are yet to be published, the data that have been released show it significantly slows progression of Alzheimer’s.”