New research suggests that the Alzheimer's drug donanemab could protect brain function for up to three years, according to findings presented at the Alzheimer's Association International Conference (AAIC) in London.
The drug, which has been licensed for use in the UK since 2024, aims to slow the progression of early Alzheimer's disease. While the National Institute for Health and Care Excellence (NICE) previously deemed its benefits insufficient to justify the cost for NHS availability, these new findings may bolster the case for its cost-effectiveness.
The study followed 1,200 patients, some of whom received donanemab for 18 months, while others initially received a placebo before switching to the drug. Researchers compared their progress with a control group using a dementia rating scale that assesses memory and thinking skills. After 18 months, a significant difference was observed between patients treated with donanemab and those who were not. This gap reportedly doubled after three years, suggesting patients may maintain memory and independence for longer.
In addition to its effects on cognitive decline, researchers noted that donanemab appeared to suppress tau, a protein linked to Alzheimer's disease. Elevated levels of phosphorylated tau (p-tau217), a marker associated with the buildup of beta-amyloid plaques and tau tangles in the brain, significantly decreased during the first 76 weeks of treatment in patients receiving the drug, while levels continued to rise in those not treated.
Alzheimer's disease is the most common form of dementia, affecting an estimated one million people in the UK, with projections indicating this number could rise to 1.4 million by 2040. Despite previous clinical trials showing donanemab's ability to slow cognitive decline, concerns have been raised regarding side effects such as brain bleeds. A review in April concluded that donanemab might offer only limited benefits, and the Cochrane Collaboration, analyzing 17 trials involving over 20,000 patients, found that while the treatments can slow progression, the effect is 'well below' what patients might notice as a clear benefit. Brain swelling and bleeding have been reported as potential risks, though experts are reportedly working to enhance the drug's tolerability.
Donanemab is administered via regular infusions, typically every two to four weeks. The cost of private treatment can be substantial, placing it beyond the reach of many patients. Hilary Evans-Newton, chief executive of Alzheimer's Research UK, stated that the new AAIC results suggest donanemab's clinical benefits may extend for years after treatment ceases. This, she noted, strengthens the evidence for both donanemab and lecanemab, another licensed drug in the UK, in slowing Alzheimer's progression, particularly when initiated early in the disease course. She added that this provides a different perspective to recent discussions questioning the benefits and safety of the anti-amyloid approach.