New brain haemorrhage drug trial recruits first UK participant
30 July 2025
Publish date: 30 July 2025
UCLH has recruited the first participant in the UK to a study looking at a new investigational drug for patients with a condition affecting the blood vessels in the brain called cerebral amyloid angiopathy (CAA).
In CAA, proteins known as amyloids build up in the walls of blood vessels in the brain, causing problems such as bleeding into the brain. It is surprisingly common. Studies suggest 7% of healthy people aged 65-74 have CAA but approximately 70% of those over 85 might be affected.
Research is ongoing into developing a treatment to reduce amyloid deposition in the blood vessels, for example by reducing the production or improving how it is cleared from the body. There are also studies investigating why only some people with CAA suffer brain bleeding. However, there is of yet no specific treatment for CAA.
Professor David Werring, consultant neurologist at The National Hospital for Neurology and Neurosurgery, Queen Square and Professor of Clinical Neurology at the UCL Stroke Research Centre, is leading the study at UCLH which is looking at an investigational drug called ALN-APP.
ALN-APP is thought to work by reducing the production of amyloid precursor protein (APP). This in turn may reduce the unwanted build-up of the amyloid protein in the walls of blood vessels in the brain. The study wants to understand whether this reduction, if it occurs, will impact the progression of CAA, for example by reducing the amount of bleeding in the brain.
Participants will be randomly assigned to receive an injection into the fluid around the spinal cord of ALN-APP, or placebo. A placebo is an inactive substance or other intervention that looks the same as, and is given the same way as, an active drug or treatment being tested.
Professor Werring said, “This is an exciting milestone for cerebral amyloid angiopathy (CAA) treatment in the UK, as it is the first time we have been able to offer the chance to participate in a trial of a drug that might directly influence the biology of amyloid protein production and accumulation to reduce the risk of intracranial hemorrhage.”
Approximately 200 participants from six countries are expected to be recruited to the study.
The study is being conducted at UCLH at the NIHR UCLH Clinical Research Facility at the CRF site within the National Hospital for Neurology and Neurosurgery, Queen Square. The trial benefits from infrastructure funded by the BRC.
The sponsor of the trial is Alnylam Pharmaceuticals.
