After the Food and Drug Administration granted approval to the first Alzheimer’s drug in nearly two decades, Biogen's Aduhelm (aducanumab), doctors are left triaging patient calls in a bid to find the appropriate patient with a mild, early course of disease.
Dr. Douglas Scharre, a neurologist and director of the division of Cognitive Neurology at Ohio State Wexner Medical Center, and clinical investigator on Biogen’s studies, explains the antibody treatment works by clearing toxic amyloid proteins from brain tissue, though patients with late stage Alzheimer’s disease are unlikely to benefit.
However the FDA issued a broad indication for approval.
"If the person is too far along in their disease, it’s not going to work, we don’t want to waste important health care dollars," Scharre told Fox News in an interview.
According to Scharre, amyloid is "a key initiating constituent" for Alzheimer’s disease, but is only the beginning. He compared the toxic amyloid protein buildup to a boulder rolling down a hill: if we can remove the boulder, perhaps we can prevent an avalanche, which underscores the idea of removing amyloid from the brain early.
If a patient starts treatment early, studies suggested a 23% slow in decline, though the Aduhelm data are complicated and not without controversy. The uncertainty surrounding whether it would receive regulatory approval involves two phase 3 clinical trials. One study met the primary endpoint and showed a reduction in clinical decline, while the other did not.
"It's not a cure, it doesn't reverse anything, it's a pretty modest impact," Scharre said. "We’ll take it, we don't have it right now so we’ll take anything."
As doctors field calls from patients interested in the drug, clinical trials are simultaneously studying the other cascade of effects, like mitigating for the tau protein, reducing chronic inflammation, keeping brain cells healthier and addressing metabolic issues, the neurologist said.
"The true help with Alzheimer's I think is going to come when we have five or six of these treatments that we can all focus on these individuals, and then we will see real, significant impact on the devastation of this disease."
The drug has its potential side effects, such as microhemorrhages and swelling, however, the clinical significance is less clear. Scharre explains that as the drug removes amyloid from the brain, it goes into the brain tissue, grabs the amyloid, takes it up through the blood vessels and carries the large protein through the blood vessel wall.
"Sometimes it causes a little bit of a leak," he said.
The microhemorrhages can accumulate right by the blood vessel wall, and easily appears on scans, though, Scharre said, "we don't really know the meaning of these things…Does it really impact brain or brain function? It's hard to say, we really don't know, it may not be very impactful at all."
He suspects lots of the microbleeds are likely unhealthy for the brain, but by itself "just small piece of blood is not necessarily destructive."
Another side effect involves swelling, which occurs when fluid carrying the blood cells leaks out and causes edema. Most patients are completely asymptomatic, and the side effect tends to crop up earlier on, though some patients experience so much swelling, it can impact their thinking and cause added confusion. However, this effect appears transient and typically resolves if the regimen is temporarily paused and recontinued.
Nearly 180 clinical trials later and 28 years in the field, Scharre is optimistic about the drug's approval. However, he noted a concerning bottleneck issue stemming from the millions of Alzheimer’s patients eligible for treatment under the FDA’s broad indication, and a significant shortage in dementia specialists, in helping to determine which patients would be appropriate to receive the drug.
"I'm sure that there's going to be a number of people that will want to have the medication even though they would not be a good candidate and that's probably going to be an issue for a lot of us."
Fox News' Alexandria Hein contributed to this report.