By Deena Beasley and Julie Steenhuysen

SAN DIEGO/CHICAGO (Reuters) – Biogen Inc on Thursday laid out more data on its experimental Alzheimer’s drug that raised no major safety alarms but also offered little compelling evidence the drug, once declared a failure, actually works.

Experts had been watching closely for any statistical abnormalities or excess safety issues that would affect how the drug is reviewed by the U.S. Food and Drug Administration (FDA). If approved, aducanumab would be the first treatment designed to delay progression of the fatal, mind-robbing disease for millions of patients.

Biogen’s fairly neutral showing and supportive comments from a panel of experts chosen by the company buoyed investor hopes that the treatment has a reasonable shot at approval. Shares in the company rose more than 3%.

The reaction from other scientists attending the meeting, however, was more mixed, with some suggesting the company should do another trial. “It was a well-curated presentation. Biogen made the argument that response to the therapy was related to cumulative dose – how much drug was received over the course of the study,” said Dr. Adam Boxer, head of the clinical trials program at the University of California, San Francisco’s memory and aging center. “I would have liked to see more data to be convinced.”

Biogen had scrapped development of the drug in March, then reversed course in October, saying a more detailed analysis showed some patients with very early forms of the disease benefited from taking higher doses over and extended period of time.

The company has said it plans to file for U.S. approval of the drug early next year.


For decades, companies have tried and failed to crack the code of Alzheimer’s. It has been 16 years since the FDA last reviewed an application for a new treatment, and the need for an effective a drug is dire. Wall Street analysts estimate aducanumab could reap $4 billion in annual sales within a few years of approval.

According to the U.S. Centers for Disease Control and Prevention, the number of people in the United States living with Alzheimer’s is expected to triple to 13.8 million by 2050.

Alzheimer’s experts on a panel organized by Biogen, expressed confidence the complicated aducanumab studies showed that the drug was able to slow progression of the disease.

“All of the data suggests this is a disease modification. That means the impact of the treatment will continue to accrue with time,” said Dr. Paul Aisen, an Alzheimer’s expert from the University of Southern California.

Dr. Ronald Petersen, an Alzheimer’s expert from Mayo Clinic who moderated the panel and has been a paid adviser for Biogen, said while one of the two studies, known as Emerge, was “overwhelmingly positive,” the twin study known as Engage, was not. “Overall, I think it’s more positive than negative,” he said of the results.

Petersen was not too worried about the rates of a brain swelling side effect, known as ARIA-E, which occurred in 35% of patients in the high-dose group.

“The side effects are there. They’re not zero. They’re to be expected. But I think they’re manageable.”

Others, however, expressed skepticism, noting that the trials were cut short early and even after all the analysis, only one of the two phase 3 studies showed a statistically significant benefit at slowing declines in cognition and daily function using the Clinical Dementia Rating Scale Sum of Boxes, a tool commonly used to gauge dementia severity.

“This reinforces what I thought before. That we need a third study. The data are encouraging, but there are still questions about whether the drug has a clinical effect,” said Dr. Howard Fillit, chief science officer of the Alzheimer’s Drug Discovery Foundation, who was at the meeting.

Dr. Eric Siemers, a former Alzheimer’s researcher for Eli Lilly and a consultant on drugs for neurodegenerative disease who was not involved with the study, said based on his read of the data he does see a signal the drug is working.

“The regulators will have a very difficult job. Do you look at the totality of the data, or require more study, which would be years away,” he said.

Stifel analyst Paul Matteis said in a note to clients that he saw aspects that were both “incrementally better and worse than expected,” and puts the probability of the drug winning approval at less than 50%.

Biogen’s shares rose 3.41% to close at $299.39.

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, Deena Beasley in San Diego and Manas Mishra in Bengaluru; editing by Bill Berkrot, Nick Zieminski and Tom Brown)