Dr. Salloway, a site principal investigator for trials of the drug, wasn’t paid for that work but has received research and consulting fees from Biogen. He said doctors should use the drug only for patients whose statuses match those in the clinical trials.
“There’s no evidence that it could be beneficial for any other stage of Alzheimer’s,” he said.
Mary Sano, director of the Mount Sinai Alzheimer’s Disease Research Center in New York City, said the criteria that she and other panelists outlined were “very important” and meant that “it’s going to be very restrictive and the ability to share this drug with a wide range of people will be significantly limited, at least at this time.”
Treating people only with mild symptoms would mean that for dementia clinicians, “most of your people in your current practice are probably not eligible,” Dr. Sano said.
In its decision, the F.D.A. acknowledged that there was not the level of evidence of benefit that the agency usually requires. As a result, it is making Aduhelm available under a program called accelerated approval, citing the drug’s ability to reduce levels of amyloid in the brain. But reducing amyloid is not the same thing as slowing symptoms of dementia. Many amyloid-reducing drugs have failed to slow decline in clinical trials, a history that makes some experts especially wary of placing confidence in Aduhelm based on the evidence produced so far.
Given the agency’s emphasis on amyloid in its approval decision, and the fact that all of the clinical trial participants had to have high amyloid levels, experts have also been surprised that the F.D.A. label does not require patients to be screened for the protein. Doctors at the Alzheimer’s Association forum all said that high levels of amyloid, typically measured by PET scan or spinal tap, should be a condition of treatment.
Several of the panelists said that, at least at the outset, relatively few doctors and clinics would have the ability to adequately diagnose, screen and treat patients.
“This is not a simple medication to use,” said Dr. Paul Aisen, director of the Alzheimer’s Therapeutic Research Institute at the University of Southern California and a co-author of an article that urged the F.D.A. to approve the drug. “I think that establishing the appropriate individuals for treatment, and monitoring treatment, requires knowledge and benefits from experience, and there are very few clinicians who have this experience.”