Another Alzheimer's disease drug has failed to help patients.  This time, it's verubecestat, a BACE inhibitor from Merck (MRK) - Get Report .

On Tuesday night, the pharma giant said a phase II/III study of verubecestat was shutting down following an interim analysis conducted by independent study monitors. The monitors concluded that there was "virtually no chance of finding a positive clinical effect." The phase II/III study, dubbed EPOCH, enrolled patients with mild to moderate Alzheimers disease.

Merck said a separate clinical trial of verubecestat being conducted in patients with prodromal Alzheimer's disease is continuing, with results expected in February 2019. 

"Alzheimer's disease is one of the most pressing and daunting medical issues of our time, with inherent, substantial challenges to developing an effective disease-modifying therapy for people with mild-to-moderate disease. Studies such as EPOCH are critical, and we are indebted to the patients in this study and their caregivers," said Roger Perlmutter, president of Merck Research Laboratories, in a statement. "While we are disappointed that a benefit was not observed in this study, our work continues with APECS, which is studying verubecestat in people with less advanced disease."

Adam Feuerstein writes regularly for TheStreet. In keeping with company editorial policy, he doesn't own or short individual stocks, although he owns stock in TheStreet. He also doesn't invest in hedge funds or other private investment partnerships. Feuerstein appreciates your feedback; click here to send him an email.