Merck's Promising Early Alzheimer's Data Can't Quell Efficacy Concerns

Phase I data for Merck & Co. Inc.'s BACE1 inhibitor, verubecestat, were published earlier this week in Science Translational Medicine (STM), spurring headlines that the first successful Alzheimer's therapy in over a decade may be upon us in 2017. But, while the early-stage data have been called encouraging, they are not enough to douse the flames of doubt that inevitably surround all Phase III Alzheimer's trials – an R&D space prone to late-stage failures. (Also see "Alzheimer's Disease: Learning the Lessons Of The Past To Prepare For The Future" - Scrip, 8 December, 2015.)

Merck confounded analysts when, on the back of a few early-stage studies, it launched two late-stage trials for verubecestat in Alzheimer's patients. First data from these Phase III and Phase...