Biogen stock price: Biogen shares tumble as Alzheimer's drug trial disappoints

Biogen stock price: Biogen shares tumble as Alzheimer's drug trial disappoints

Alzheimer's is the most common form of dementia.

Biogen - the largest biotech based in MA - and its Japanese partner Eisai said they were halting two late-stage clinical trials of the drug after concluding it was unlikely to benefit patients.

The news that trials for the drug called aducanumab was a huge blow to the Alzheimer's community because this drug was meant to be one of the most promising drugs on the market for combating early-onset Alzheimer's. Without potential future revenue from Alzheimer's, Biogen has poor growth prospects as it faces patent issues over its big-selling multiple sclerosis drug Tecfidera and possible competition to spinal muscular atrophy drug Spinraza, Wall Street analysts said. But drugmakers "keep trying, hoping that the path they are on is going to give blockbuster drugs".

"This one hurts", Isaacson said.

The companies will also discontinue a mid-stage study and a long-term extension study of aducanumab, which was created to target the brain-destroying protein beta-amyloid. Results from the studies aren't expected for about another two years. Despite that dominance, drug development in Alzheimer's has yielded a long string of failures.

"It was a huge gamble from the start", said Harvard neurologist Dr. Rudy Tanzi, who directs the Genetics and Aging Research Unit at Massachusetts General Hospital.

The idea that blocking the formation of the amyloid plaques that are seen in the brains of people with AD has dominated drug development of the disease for years - but has seen dozens of anti-amyloid candidates fail in clinical testing. In 2013, Pfizer scrapped another antibody, bapineuzumab, when it didn't surpass placebo effects in another phase three trial.

MSD also tried to treat dementia by inhibiting the production of beta-amyloid with a β-secretase (BACE) inhibitor, verubecestat. That's despite analysts' expectations that the second drug would also likely be discontinued. This will determine if a monthly dosage of Aducanumab can effectively slow down the cognitive and functional impairment in patients.

The decision was taken following a futility analysis conducted by an independent data monitoring committee ("IDMC"). It found the trials were unlikely to meet their primary goals at completion.

"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.

Those finer details may uncover ways in which amyloid-attacking drugs might be helpful to those diagnosed with Alzheimer's, Isaacson said.

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