Biogen and Eisai have stopped two global Phase III trials of the Alzheimer's drug aducanumab, after interim analyses indicated that the agent was ineffective and would not meet the primary endpoint.

The ENGAGE and EMERGE studies were designed to evaluate the efficacy and safety of aducanumab in people with a confirmed diagnosis of mild cognitive impairment (MCI) or mild Alzheimer's disease.

The decision to stop the trials was said to be based on an analysis that suggested they were unlikely to improve people's memory and sufficient thinking by the end of the trial, and was not related to any safety concerns, the firms noted.

“Alzheimer’s is a complex disease and to reflect this we need a range of drug discovery programmes targeting different aspects of the disease. The Alzheimer’s Research UK Drug Discovery Alliance currently has 23 active drug discovery projects targeting harmful brain inflammation and other damaging processes in the disease,” said Hilary Evans, chief executive at Alzheimer’s Research UK.

“While today’s news is a set-back, it’s important to remember there are more than 20 potential Alzheimer’s drugs still in final stage clinical trials. We must continue to support the pioneering researchers across the world who are taking us closer to unravelling this complex disease. Now is the time to push even harder for the funding that will accelerate the search for that much-needed Alzheimer’s treatment.”

The drug is an antibody designed to target amyloid, a protein that builds up in the brains of people with Alzheimer's at an early stage in the disease process.

Biogen caused a stir back in 2014 by saying that it was moving the investigational Alzheimer’s drug into Phase III on the back of promising early-stage data in which patients exhibited statistically significant cognitive improvements by 54 weeks, at a time when the Alzheimer’s field was littered with failed compounds.