Alzheimer’s disease research has taken another hit with the failure of AstraZeneca and Eli Lilly’s experimental (BACE) inhibitor lanabecestat.

The firms said they would discontinue two Phase III trials of the experimental drug after an independent data monitoring committee found that they were unlikely to meet their primary endpoints.

The AMARANTH trial randomised patients with early Alzheimer’s disease to receive lanabecestat, 20mg or 50mg, or placebo orally once daily for 104 weeks, to assess the drug’s effect on change from baseline on the 13-item Alzheimer's Disease Assessment Scale-Cognitive Subscale (ADAS-Cog13).

The DAYBREAK-ALZ trial, which had the same endpoint, randomised patients with mild Alzheimer’s disease dementia to receive either lanabecestat, 20mg or 50mg, or placebo orally once daily for 156 weeks.

“We are saddened by this outcome as our researchers are working tirelessly to find a solution for the many people who are impacted by this devastating disease,” said Menelas Pangalos, executive vice president, IMED Biotech Unit, AZ.

“We are committed to ensuring our findings can be used to inform further research in the Alzheimer’s community, given the importance of finding a treatment for this disease.”

The AZ and Lilly BACE alliance for lanabecestat remains in place and the companies will now work with the clinical trial sites involved to implement the discontinuations, the firms noted.

Evidence suggests that inhibiting BACE could reduce amyloid plaque formation and modify the progression of Alzheimer's disease. However, this area of research has been marred by a couple of high-profile setbacks.

Safety concerns prompted Janssen to pull the plug on a development programme testing its BACE inhibitor atabecestat for Alzheimer’s disease back in May, while MSD terminated a second trial testing its BACE inhibitor verubecestat in February, after an external data monitoring committee concluded that it was unlikely that a positive benefit/risk would be established.

On the plus side, Biogen’s BACE inhibitor elenbecestat has been showing early signs of promise, having shown itself to be safe as well as effective in reducing brain amyloid beta levels in a recently presented Phase II clinical trial.