Two late-stage clinical trials of a drug for Alzheimer’s disease have been stopped because they aren’t likely to produce promising results, two companies involved with the research announced Thursday.

The Phase 3 trials, named ENGAGE and EMERGE, were studying the effectiveness and safety of aducanumab in people with mild cognitive impairment due to Alzheimer’s disease and mild Alzheimer’s disease dementia, biotechnology company Biogen of Cambridge, MA, and pharmaceutical company Eisai Co. Ltd. of Tokyo said. An independent data monitoring committee determined that completed studies were unlikely to show that the investigational compound benefited people with Alzheimer’s when compared with placebo, the companies said.

“This disappointing news confirms the complexity of treating Alzheimer’s disease and the need to further advance knowledge in neuroscience,” Biogen CEO Michel Vounatsos said in a statement. “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.”

Biogen said researchers will share data from the two ended trials at future medical meetings so that others can learn from them.

The company also said it will discontinue its EVOLVE Phase 2 safety study and the long-term extension of the PRIME Phase1b study of aducanumab and is assessing whether to begin a Phase 3 secondary prevention trial of the drug.

Vounatsos said the company will continue studying other potential therapies for Alzheimer’s disease.

Biogen and Eisai have collaborated on the development and commercialization of aducanumab globally since October 2017. The Food and Drug Administration has granted “fast track” designation for the development of the drug, a status allowing for priority reviews of drugs with the potential to treat serious conditions and tackle key unmet medical needs.