MSD’s Alzheimer’s drug failure undermines potential treatment pathway

MSD, known as Merck in North America, has announced that it has been forced to cancel a Phase 2/3 trial studying the potential therapeutic effects of verubecestat in Alzheimer’s patients. The failure of the drug to show efficacy draws into question how amyloid plaques are being targeted and whether this is now a viable target for treatment.

The trial was stopped by an independent panel of experts that concluded that there was "virtually no chance of finding a positive clinical effect". The news comes as a further blow to the hope of developing a new treatment for Alzheimer’s, which has not had a new form of treatment reach the market in over a decade. It is the second such failure to occur within the industry in the last few months, with Lilly having to abandon its own Alzheimer’s treatment after it displayed no statistical difference to patients compared with the placebo arm.

It’s a disappointing development for MSD but the real worry lies in the method by which the treatment was predicted to improve patients. The drug targets the plaques that build up within the brain of Alzheimer’s patients, called amyloid, but so far treatment that have targeted the plaque have failed to show benefits.

As the full data is yet to be released, there is only speculation as to why the treatment did not work but there is a suspicion that treating patients after the plaques have already developed is not enough to prevent damage. Potentially, treating patients early may have the desired affects or not enough of the drug was reaching the brain. It could also mean that the beta amyloid theory that currently speculates that the abnormal protein clusters are not one of the main causes of the news.

"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 Dr. Roger M. Perlmutter, President of MSD Research Laboratories. "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."

As mentioned by Perlmutter, MSD will continue with studies of the drug in another clinical trial – with results from this trial expected by February 2019.

Ben Hargreaves