US drugmaker Merck & Co. has said it will halt its APECS randomized, placebo-controlled, parallel-group, double-blind Phase 3 clinical trial evaluating the efficacy and safety of verubecestat MK-8931 in people with prodromal Alzheimer’s disease (AD).

MK-8931 is an investigational small molecule inhibitor of the beta-site amyloid precursor protein cleaving enzyme 1 (BACE1).

The company known outside the US as MSD said the decision to stop the study follows a recommendation by the external Data Monitoring Committee (eDMC), which assessed the overall benefit/risk during a recent interim safety analysis. Merck said the eDMC concluded it was unlikely that a positive benefit/risk could be established if the trial continued.

The US drugmaker said the data from the study will be presented at an upcoming medical meeting.

Merck became the second within days to reveal the lack of success in an advanced clinical trial with a hitherto promising Alzheimer’s candidate. Germany’s Boehringer Ingelheim said earlier this week it planned to shift the focus of its investigational compound BI 409306 to ongoing clinical trials with schizophrenia patients after the drug failed to outperform a placebo in Phase II trials with 450 patients for the indication Alzheimer's.

Commenting on the US company’s problems, Roger M. Perlmutter, president of Merck Research Laboratories, said Merck remains committed to developing novel therapies for the treatment of Alzheimer’s and other neurodegenerative diseases.”