March 21 (UPI) -- Biotechnology giant Biogen, which was developing an Alzheimer's disease drug with Japanese-based Eisai Co. Ltd., announced Thursday that it was ending its Phase 3 trial of the drug because it was not likely to "meet their primary endpoint."
The drug aducanumab was being developed as an effective treatment for those with mild cognitive impairment due to Alzheimer's and dementia. Biogen had been developing it on its own until it joined forces with Eisai in 2017.
"This disappointing news confirms the complexity of treating Alzheimer's disease and the need to further advance knowledge in neuroscience," Michel Vounatsos, chief executive officer at Biogen, said in a statement.
"Biogen's history has been based on pioneering innovation, learning from successes and setbacks. Driven by our steadfast commitment to patients and our strong business foundation, we will continue advancing our pipeline of potential therapies in Alzheimer's disease and innovative medicines for patients suffering from diseases of high unmet need," he added.
Shares in Biogen tumbled 28 percent Thursday off of the news. Biogen is one of the largest biotech companies in the world with a market value of $63 billion.
Effective treatments for Alzheimer's continue to be elusive for some of the world's top drug makers. Roche Holding AG also stumbled in past tests and trials in hopes of developing effective regiments.
"This was the largest opportunity and the most high-profile pipeline event for trial events in the entire space, you could argue, let alone for Biogen," Jared Holz, a healthcare analyst at Jefferies, told CNBC.
"We've been talking about this for several years with an expectation we'd get a readout in 2020. There was obviously a chance you could have a futility analysis in 2019, but investors thought we were past that point," Holz continued.