A major trial has been launched testing a new Alzheimer's drug designed to target the root cause of the disease.
The drug, MK-8931, suppresses production of molecular building blocks that create toxic protein in the brain.
Deposits of amyloid beta protein are thought to be the chief underlying cause of Alzheimer's.
The four-year Phase II/III Epoch study will eventually enrol up to 1,700 patients from around the world.
Dr Richard Perry, one of the trial investigators from Imperial College NHS Trust, said: "It is important that there's still a focus on Alzheimer's research and it is encouraging to see research being undertaken to bring new treatment options to patients in the future."
Dr Paul Robinson, medical director of the UK arm of drug manufacturer MSD (Merck & Co), said: "Although MK-8931 is very early in development and a long way off being licensed, taking promising potential treatments for Alzheimer's disease into phase II/III is a very important milestone."
Dr Eric Karran, from the charity Alzheimer's Research UK, said: "It takes many years of research in the lab before a clinical trial can begin, and it's great to see research into potential new treatments for Alzheimer's disease progressing in this way.
"This drug is designed to target the first step in the chain of events that produces the amyloid protein, which is a hallmark of Alzheimer's disease. The challenge for these trials will be to determine whether the drug is safe for use in people with Alzheimer's and, crucially, whether it has benefits for these people.
"We look forward to seeing the results of these trials in four years' time."