Biogen Inc. shares fell 28% in premarket trading Thursday after Biogen and Eisai Co. Ltd., a Japan pharmaceutical company, said they are ending two Phase 3 trials for a treatment for Alzheimer’s disease.
The companies said that an analysis by an independent data-monitoring committee found “the trials were unlikely to meet their primary endpoint.” The companies said safety concerns weren’t the basis for that recommendation.
Biogen and Eisai have worked together on the treatment—called aducanumab—since October 2017, the companies said. The trials were supposed to evaluate the treatment for people who had mild Alzheimer’s disease dementia and people with mild cognitive impairment as a result of Alzheimer’s.
The treatment was also given fast-track designation from the U.S. Food and Drug Administration.
“This disappointing news confirms the complexity of treating Alzheimer’s disease and the need to further advance knowledge in neuroscience,” Biogen Chief Executive Michel Vounatsos said in prepared remarks.
The companies said they would also end a Phase 2 safety study and the extension of a Phase1b study for the treatment. They will decide whether to initiate a Phase 3 secondary prevention trial for the treatment, they said, after continuing to look at data.