Our Hope—And Questions—About Biogen and Eisai’s Latest Alzheimer’s Drug Trial Results

After years of failure, including some pharmaceutical companies calling off Alzheimer’s research altogether, Biogen offers a glimmer of hope: New data from a Phase 2 trial showed that a drug in preliminary testing stages might actually work to slow cognitive decline in Alzheimer’s patients.

The news comes as a surprise, considering that the treatment, a drug dubbed BAN2401, was considered a failure after reaching the one-year testing mark back in December 2017. But after looking at data over 18 months, Biogen and its Japanese drug manufacturing partner Eisai said that one dose they tried—the highest of five that were tested—was able to both reduce the beta-amyloid plaques in the brain, a hallmark of Alzheimer’s, and slow cognitive decline.

This is big news, since almost every other drug that attacked amyloid has resulted in failure—even when the drug was able to reduce the levels of amyloid in the brain.

It was an announcement that resulted in a $12 billion-dollar surge in Biogen’s valuation.

The drug was tested on 856 patients in the early stages of Alzheimer’s disease. After six months, those who were given the highest dose (10 mg) started showing a difference in cognition when compared to the placebo group, Biogen said in a statement. PET scans that measure beta-amyloid, the protein that accumulates in the brain of an Alzheimer’s patient, showed that the drug was able to reduce levels of the protein, too.

The drug’s success relies on the leading theory in Alzheimer’s—the amyloid hypothesis—being valid. That theory hypothesizes that beta-amyloid plaques cause the memory-obliterating effects in the brain. But it’s been contested as of late, especially after a drug that helped reduce the plaques did not slow down or stop cognitive decline in Alzheimer’s patients.

Biogen is not revealing the full results of the trial yet, though. According to the press release, those will be available at future academic conferences—most likely the Alzheimer’s Association conference on July 25.

The next question on everyone’s mind: When can I get my hands on this drug? Before the drug is available, a large-scale study needs to be conducted that proves its effectiveness. But before that happens, there are still other concerns to address.

Biogen used an in-house metric to measure cognitive decline rather than the standard tests used in Alzheimer’s studies, like the Montreal Cognitive Assessment. It’s expected that when the full results are revealed, outside researchers will be able to get a better handle on the significance of the cognitive differences between the placebo group and the high-dose group. And since we know the trial was divided into at least five doses, it’s unclear how many people participated in the one that was reportedly successful.

For now, though, the tentative success of BAN2401 is bolstering a field that needed some positive news. “This is really the first large study in which [beta-amyloid plaque] reduction correlated with a reduction in cognitive decline,” said Dr. Lynn Kramer, chief medical officer of Eisai, in a statement. “And that’s a very important correlation.”