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Biogen to make case to skeptics for its controversial Alzheimer's drug

By Deena Beasley and Julie Steenhuysen

By Deena Beasley and Julie Steenhuysen

SAN DIEGO, Dec 5 (Reuters) - Biogen Inc, looking to win over skeptics and health regulators, later on Thursday will present highly anticipated data on its experimental Alzheimer's drug aducanumab, which the U.S. biotech company had declared a failure earlier this year.

The turnabout has raised concern that the company is being more optimistic than its trial results warrant as it makes a case for a desperately needed treatment that, if approved, could be the first to slow progression of the mind-wasting disease.

For Biogen, the financial prospects are enormous. Wall Street analysts have forecast annual aducanumab sales reaching nearly $4 billion a year by 2024.

The decades-long search for a disease-modifying Alzheimer's treatment is littered with failures, and experts say aducanumab still needs to overcome serious questions over Biogen's new analysis of the trials.

"I've never seen it done where a trial has been stopped (for futility) and then they come back and say, 'Hey, we did some more analysis and guess what? It's better,'" said Laurie Ryan, who heads the dementias of aging branch at the National Institute on Aging. "None of us has seen the raw data. We hope we see that."

Biogen's drug had been seen as a potential game changer, offering proof of the long-held theory that removing a toxic protein called beta-amyloid from the brain would slow progression of the disease.

Those hopes appeared to be dashed in March with an announcement that an interim analysis of two late-stage trials indicated they were likely to fail.

In October, however, Biogen surprised investors and the medical community, saying additional data showed a significant benefit in one of the twin trials, and that results for a subset of patients in the second trial support those findings.

Biogen said after discussions with the U.S. Food and Drug Administration, the agency encouraged it to file for approval.

The company will present the additional aducanumab data at the Clinical Trials on Alzheimer's Disease conference in San Diego.

Skeptics have raised numerous questions about scientific standards employed by Biogen in its more positive assessment, including a decision to compare results from a subset of patients who received a higher dose of aducanumab in each trial to the full placebo group.

Dr. Adam Boxer, head of the Alzheimer's clinical trials program at the University of California, San Francisco, said in a phone interview that a big question is "why did they see efficacy in one Phase III trial and not the other?"

Others have questioned the drug's safety data and other aspects of the trial analysis.

"The safety concern is swelling or even bleeding in the brain that may result from the process of lowering beta-amyloid levels," said Dr. Joshua Grill, a neurological disorders expert from the University of California, Irvine.

Some aducanumab patients were taken off the drug due to brain swelling and later allowed back into the trial, further complicating findings.

Biogen has partnered with Japan's Eisai Co Ltd to develop aducanumab as well as BAN2401, which works in a similar way. (Reporting by Julie Steenhuysen in Chicago and Deena Beasley in San Diego; editing by Bill Berkrot)