Biogen and Eisai have announced that they are discontinuing the ENGAGE and EMERGE trials, which were designed to test the efficacy and safety of aducanumab in patients with mild cognitive impairment caused by Alzheimer’s disease and mild Alzheimer’s disease dementia.

The phase 3, multicenter, randomized, double-blind, placebo-controlled, parallel-group trials were canceled not because of safety concerns but because of a futility analysis conducted by an independent data monitoring committee that indicated the drug would not meet the trials’ primary endpoint, which was the slowing of cognitive and functional impairment as measured by changes in Clinical Dementia Rating–Sum of Boxes score, compared with placebo.

In addition to ENGAGE and EMERGE, the phase 2 EVOLVE safety study and the long-term extension of the phase 1b PRIME study have also been canceled. Data from the ENGAGE and EMERGE trials will be presented at future medical meeting.

Aducanumab is a human monoclonal antibody derived from B cells collected from healthy elderly subjects with no cognitive decline or those with unusually slow cognitive decline through Neurimmune’s technology platform called Reverse Translational Medicine. It was granted Fast Track designation by the Food and Drug Administration.

This disappointing news confirms the complexity of treating Alzheimer’s disease and the need to further advance knowledge in neuroscience. We are incredibly grateful to all the Alzheimer’s disease patients, their families, and the investigators who participated in the trials and contributed greatly to this research,” Michel Vounatsos, CEO at Biogen, said in a press release.