A groundbreaking dementia drug that could slow Alzheimer's disease before symptoms develop is being tested in a major trial involving approximately 1,600 participants. The treatment, known as trontinemab, works by removing toxic amyloid proteins from the brain and may prove more effective than previous medications.
How Trontinemab Works
Trontinemab is a next-generation anti-amyloid drug developed by Swiss pharmaceutical giant Roche. It combines a previously tested drug, gantenerumab, with a “shuttle” molecule that helps the antibody cross the blood-brain barrier more effectively. This innovative approach allows more of the drug to reach the brain, potentially increasing its efficacy.
Professor Rob Howard, an expert in old age psychiatry at University College London, explained: “The anti-amyloid antibodies that have been used in the past, probably about 1% of what’s infused into the patient actually gets into the brain. By linking one of the antibody molecules to a molecule of transferrin, you sort of trick the brain into taking it up and get more of the antibody into the brain, more quickly.”
Trial Details and Recruitment
The study is being conducted across 18 countries and is recruiting people aged 55 and over who do not have cognitive symptoms but may be at high risk of Alzheimer's disease. Blood tests will be used to identify patients who are most likely to benefit from the treatment. Trontinemab is administered in seven monthly infusions, followed by doses every three months.
Promising Early Results
Smaller studies have shown encouraging results. A study involving 178 patients and 477 brain scans found that trontinemab cleared amyloid in the brain in nine out of 10 patients after 28 weeks. Experts suggested that those on the highest dose could be free of amyloid in as little as three months. Additionally, the drug appears to cause fewer incidents of brain swelling and bleeding compared to earlier anti-amyloid drugs.
Dr Richard Oakley, associate director of research and innovation at Alzheimer's Society, said: “These trontinemab trials are among the most anticipated and exciting developments we have seen in Alzheimer’s research for some time, and we look forward to the results.”
Expert Reactions and Cautious Optimism
While many experts are optimistic, some urge caution until more data is available. Dr Rachel Buckley, associate professor of neurology at Harvard Medical School, stated: “If these trials are positive, the game changes.” However, Professor Howard warned: “What we don’t know yet is whether it has more of an effect on the actual Alzheimer’s disease process and the symptoms. No one has ever shown that you can actually reduce the number of people who move from having amyloid in their brains to having dementia with this treatment. It’s an interesting concept but until you’ve actually demonstrated that these drugs stop the emergence of dementia in people who were probably going to get it, we should be very careful about talking about ‘game-changers’.”
Dr Emer MacSweeney, consultant neuroradiologist and CEO at Re:Cognition Health, which is participating in the trial, said: “This is another hugely encouraging step forward in Alzheimer's research and reflects the remarkable momentum we are now seeing in the development of disease-modifying treatments.” She added that lecanemab and donanemab, two similar drugs licensed in the UK but rejected for NHS use due to cost, “have already begun to transform the lives of many patients with early Alzheimer's disease by slowing progression and allowing people to maintain their independence for longer.”
Comparison with Existing Drugs
Lecanemab and donanemab are anti-amyloid drugs that were licensed in the UK but were not approved for NHS use because their benefits were considered too small to justify their cost. Trontinemab aims to improve upon these treatments by delivering more of the antibody to the brain, potentially increasing efficacy and reducing side effects.
Hilary Evans-Newton, chief executive of Alzheimer’s Research UK, emphasized the need for larger trials to demonstrate meaningful benefits. She said: “The first wave of anti-amyloid drugs has already shown that it is possible to change the course of Alzheimer’s, moving from managing symptoms to targeting the underlying disease. Now, the next generation of potential treatments is asking an even bigger question: can we intervene earlier, more effectively and, we hope, more safely, before memory and thinking are badly affected? That is why the idea of one day protecting brain health before symptoms take hold with a ‘statin for the brain’ is so powerful.”
What This Means for Patients
If successful, trontinemab could represent a major step forward in the fight against Alzheimer's disease, potentially allowing early intervention before significant cognitive decline occurs. The trial is expected to provide crucial data on whether the drug can prevent or delay the onset of dementia in high-risk individuals.
