New findings presented at the Alzheimer's Association International Conference (AAIC) in London indicate that the Alzheimer's drug donanemab may protect the brain for up to three years, potentially delaying disease progression and preserving cognitive function.
The research, which followed 1,200 patients, showed a significant difference in cognitive function between those who received donanemab and those who did not. After 18 months of treatment, the gap in dementia rating scale scores, which assess memory and thinking, had doubled by the three-year mark. Researchers suggest this indicates patients could maintain their memory and independence for longer.
Drug Mechanism and Biomarkers
The study also observed that donanemab appeared to suppress tau, a protein naturally present in the brain that is linked to Alzheimer's disease. While tau typically aids brain cell function, elevated levels, particularly p-tau217, are associated with the buildup of beta-amyloid plaques and tau tangles in the brain. The researchers reported a significant decrease in p-tau217 levels during the first 76 weeks of treatment in patients taking donanemab, while levels continued to rise in those not receiving the drug.
Donanemab, which is administered via transfusion every two to four weeks, was licensed for use in the UK in 2024. However, it has not been made available on the National Health Service (NHS) due to a prior assessment by the National Institute for Health and Care Excellence (NICE) that deemed its benefits insufficient to justify the cost.
Concerns and Future Outlook
Despite the promising new data, donanemab has been associated with side effects, including brain bleeds and swelling, observed in previous clinical trials. A review in April suggested that treatments designed to remove amyloid protein from the brain, including donanemab, might offer only limited benefits that are 'well below' what patients would notice as a clear improvement. The cost of private treatment also places it out of reach for many.
Hilary Evans-Newton, chief executive of Alzheimer's Research UK, commented that the new AAIC results strengthen the evidence for donanemab and a similar drug, lecanemab. She highlighted that these medications can slow Alzheimer's progression over the long term and are most beneficial when initiated early in the disease course. This perspective contrasts with recent discussions that have raised doubts about the efficacy and safety of amyloid-targeting treatments.