Small-cap companies also working on treatments also climbed. Cassava Sciences Inc. surged 19%, while Annovis Bio Inc. gained 31%. The Nasdaq Biotech Index traded to a session high led by other Alzheimer’s stock plays like AC Immune and Prothena Corop.
Trial Reversal
Two years ago, aducanumab appeared destined to take its place on the heap of failed Alzheimer’s disease drugs. In early 2019, Biogen and Tokyo-based Eisai discontinued the two big trials after an initial analysis indicated they were unlikely to work. The drug appeared to be all but dead.
But later that year, the companies stunned outside researchers when they reversed course, and declared that one of the trials had worked after all.
In November 2020, the FDA issued an unusual joint report with Biogen ahead of a meeting of an agency advisory panel, calling the data backing the drug “exceptionally persuasive.” That seemed to put it on a glide path for approval.
Days later, the FDA’s outside panel of medical experts showed itself to be far more skeptical. It voted 8-1, with two undecided, that the single successful trial was insufficient to prove the drug’s efficacy.
In January, Biogen and Eisai said the FDA pushed back its deadline to decide on the drug by three months to June 7. The companies submitted an analysis and clinical data in response to an FDA request for information that would take additional time to review, they said at the time.
Patient Push
In the months leading up to the decision, patients and advocates pushed hard for approval. The Alzheimer’s Association helped organize a session for patients to talk to FDA staff in January. In May, the group followed up with a five-day advertising and social media blitz. Critics of the drug have also been outspoken in recent months, publishing journal articles and opinion pieces highlighting flaws in the drug’s data.
The approval is likely to put new strains on health-care systems. A 2017 Rand Corp. analysis estimated that 88 million Americans 55 and older might be eligible for initial screening for a drug like aducanumab, but only 2.4 million would ultimately be candidates for treatment.
Each step between screening and treatment poses a potential bottleneck. A limited number of dementia specialists are available to evaluate patients. Infusion treatment centers were preparing for a rush of demand before the decision, with some weighing extending their hours or adding capacity.
“One thing we know is there’s probably not enough infusion chairs in America to support the potential onslaught of people,” Charlie Schadewald, CEO of Wasatch Infusion in Utah, said in an interview in May.
Coverage Pressure
Payers including private insurers and Medicare will have to determine how to reimburse for the drug and associated care. Medicare doesn’t cover most scans for amyloid. The agency said last month that it was evaluating coverage and payment rules for aducanumab ahead of the FDA decision.
Doctors worry that there may be pressure to approve therapy for additional Alzheimer’s patients. That decision is complicated by wiggle room in interpreting results of cognitive assessments.
“There are specific criteria, but they’re a little bit fuzzy,” said Erik Musiek, a neurologist at Washington University in St. Louis in a May interview.
He said he’s concerned that physicians might feel pressure from patients whose impairment is either too severe or not sufficient to meet the criteria for aducanumab.
—With assistance from Anna Edney, John Tozzi and Cristin Flanagan.
This article was provided by Bloomberg News.