Merck & Co. hits Alzheimer’s setbacks

In the latest blow to the hypothesis that amyloid plaques on the brain cause Alzheimer’s disease, Merck & Co. is ending a study of verubecestat after an early review of data showed the compound was not benefiting patients. Verubecestat prevents new amyloid-β plaques from forming by blocking the enzyme β-secretase. The Phase II/III study being halted tested verubecestat in people with mild to moderate Alzheimer’s disease, a population that could already have too much plaque for the drug to be useful. Merck will continue a Phase III study of the drug in people with a very early form of Alzheimer’s.