Roche's Trontinemab Cuts Alzheimer's Brain Bleed Risk
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- Trontinemab, Roche's experimental antibody, piggybacks on the brain's iron-transport receptor to cross the blood-brain barrier, allowing much lower doses than existing amyloid-clearing drugs lecanemab and donanemab.
- Results presented on 14 July in London by Luka Kulic at Roche in Basel showed fewer than 5% of trontinemab participants developed amyloid-related imaging abnormalities (ARIA), versus around 20% with lecanemab and 40% with donanemab; ARIA can cause serious bleeds, swelling, and seizures.
- Trontinemab drove brain amyloid to normal levels in 92% of participants within six months of monthly dosing — a milestone that takes more than a year to reach in roughly three-quarters of patients on existing antibody drugs.
- Independent experts Nick Fox at University College London and Luciana Maffei at the University of Oxford said the drug's efficient brain entry makes it "less invasive" and predicted it could match or outperform approved therapies on cognitive decline, though Roche has not yet released cognitive-outcome data.
- Roche is now planning two larger trials: one to test whether trontinemab slows cognitive decline in early-stage Alzheimer's, and another to see whether it can prevent the disease in people at high risk.
Why it matters: If larger trials hold, trontinemab could neutralize the chief safety complaint against amyloid therapies (brain bleeds and swelling in up to 40% of patients), potentially unlocking NHS access in the UK where lecanemab and donanemab remain unavailable. Fewer infusions and monitoring scans per patient may also push costs down enough to justify reimbursement.
