A small number of British sufferers with mild-to-moderate stage Alzheimer's could get access to the drug, known as MK-8931, when the trial starts in the new year, The Telegraph reported.
Early tests indicate the drug could be remarkably effective at halting the biochemical process, known as the 'amyloid cascade', that causes the devastating brain disease.
Alzheimer's results from a mass die-off of brain cells, linked to the build-up of structures between cells called amyloid plaques.
Researchers are increasingly convinced that the best way to attack Alzheimer's is to stop the underlying disease before the plaques form in large numbers.
As a result they have started to look at agents which tackle the key ingredient of the plaques, a protein called beta amyloid.
In a pilot study of 200 healthy volunteers, drugs firm MSD showed that its agent MK-8931 reduced levels of beta amyloid in spinal fluid by 92 per cent.
Now it is rolling out the study to 1,700 people with mild-to-moderate Alzheimer's worldwide. Half will be randomly assigned the drug and half a placebo. Some of the study participants will be in Britain, although numbers have yet to be finalised.
"The idea of this drug is to stop the production of abnormal levels of beta amyloid in the brain. It's about getting in early, so that if less amyloid is produced less plaques will come together," Dr Richard Perry, a consultant neurologist at lecturer at Imperial College Healthcare National Health Service Trust, said.
"From what I have seen of the phase one trial results, this drug looks encouraging in terms of reducing the level of abnormal beta-amyloid in spinal fluid," Perry said.
The research scientists will measure rates of cognitive decline in those on the pill against those on the dummy, using mental ability tests and assessing how well they carry out normal day-to-day functions, the paper said.
They are not expecting it to improve the abilities of sufferers: most experts think that there is no way of reversing the damage Alzheimer's has already inflicted.
Since they are looking at relatively early-stage Alzheimer's, the differences will take some time to accrue and the researchers said results will not be ready until 2016.
The study was presented to the American Academy of Neurology.