The news darkened the prospects for an Alzheimer's treatment any time soon, and raised still more questions about why so many efforts to develop one have failed, leaving nearly 6 million Americans with no options.
Then, in an October turnabout that shocked the Alzheimer's field, Biogen reversed itself and said that parsing the data differently suggested aducanumab was effective, at high doses. The announcement met plenty of skepticism and concern.
Now, the company has presented more detailed data backing up its claim at a major Alzheimer's conference in San Diego. On the Biogen panel on Thursday, behavioral neurologist Sharon Cohen, who helped lead the aducanumab testing, said the data showed that the drug could help people with early Alzheimer's function better for longer.
"The community at large fears Alzheimer's disease — and rightly so — largely because of the loss of autonomy that comes with this disease," she said. "So slowing loss of autonomy, for me as a clinician, is key."
The Biogen presentation dug into the two late-stage clinical trials of the drug and the differences in their findings.
"The data is complex," said panel member Dr. Paul Aisen of the USC Alzheimer's Therapeutic Research Institute.
Central among the complexities: The trials of more than 3,000 patients with early Alzheimer's included different sub-groups who were given different doses and yielded differing results.
Still, Aisen said, "I think we are left with an overall positive interpretation of the data from the aducanumab studies that therefore represents a truly major advance for the field."
Many questions remain, including — as put to the panelists — "How big a deal is this?" The testing lasted 18 months and found an advantage for the patients on the drug, but their decline still continued.
"We're looking for a biological foothold against Alzheimer's that we can build on," said panel member Steven Salloway of Brown University. "So these effects are small, but I think they are meaningful and I hope they're the beginning of a process that we can add to."
The data presented found that the drug did make a difference with two hallmarks of Alzheimer's: plaques and tangles that gum up the brain.
Biogen plans to apply for federal approval to be able to bring aducanumab to market next year. Its stock rose slightly after the presentation.
Dr. Rudy Tanzi, a professor of neurology at Harvard and Massachusetts General Hospital, watched the Biogen presentation and came away saying the data looked great for the amyloid hypothesis, which posits that clumps of amyloid beta protein are key to Alzheimer's.
"I think it will open the door for many other drugs that target amyloid, some of which we're working on at Mass. General," he says.
Now, Tanzi says, "I think the big question will be whether they get approval, and how many restrictions there will be on it," because the clinical trials turned up safety concerns: the drug caused transitory brain swelling in some patients.
And one more question, he says, if aducanumab is approved: "How do we afford it? It's a very expensive therapy" — a monthly infusion — " and right now you want to use it very early in the disease, preferably even pre-symptomatically."
That could mean millions of people on a monthly infusion that costs thousands of dollars per dose. Work is under way, Tanzi says, on a pill that could help keep amyloid accumulations at bay, so one eventual possibility would be using aducanumab first and then a cheaper pill.
More immediately, he expects the FDA to need at least a year or two to decide whether to approve the drug and if so, which restrictions to impose on its use.
This segment aired on December 6, 2019.