Merck, known as MSD outside the United States and Canada, announced that it will be stopping protocol 019, also known as the APECS study, a phase 3 study evaluating verubecestat (MK-8931), an investigational small molecule inhibitor of the beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), in people with prodromal Alzheimer’s disease (AD). The decision to stop the study follows a recommendation by the external Data Monitoring Committee (eDMC), which assessed overall benefit/risk during a recent interim safety analysis. The eDMC concluded that it was unlikely that positive benefit/risk could be established if the trial continued. Data from the APECS study will be presented at an upcoming medical meeting.

“We are disappointed with this outcome, especially given the lack of treatment options for patients suffering from Alzheimer’s disease,” said Dr. Roger M. Perlmutter, president, Merck Research Laboratories. “We are grateful to the patients and caregivers who participated in this study, and despite this outcome, Merck remains committed to developing novel therapies for the treatment of Alzheimer’s and other neurodegenerative diseases.”

APECS is a randomized, placebo-controlled, parallel-group, double-blind phase 3 clinical trial evaluating the efficacy and safety of verubecestat in people with prodromal AD. Subjects are randomized to receive placebo, or 12 mg or 40 mg verubecestat, once-daily. The primary efficacy outcome of the study is change from baseline in the Clinical Dementia Rating Scale-Sum of Boxes (CDR-SB) score following 104 weeks of treatment.