The first new drug against Alzheimer's disease in nearly two decades received a conditional and controversial green light from U.S. drug regulators on Monday.
The U.S. Food and Drug Administration approved biotech company Biogen's antibody drug aducanumab. The drug reduces the amyloid plaques that riddle the brains of Alzheimer's patients.
But the approval drew sharp criticism from experts who note that the company has not proved that it slows the debilitating cognitive decline in patients with the disease.
The FDA will require Biogen to continue testing the drug after it is released and ultimately demonstrate that patients actually do fare better on the drug.
In the meantime, the company said the drug will cost each patient $56,000 per year, but is likely to be covered by most insurers, including Medicare.
Alzheimer's, a degenerative neurological disease, is responsible for roughly two-thirds of the 50 million cases of dementia worldwide, according to the World Health Organization.
Aducanumab, marketed as Aduhelm, is the first approved treatment to target the underlying disease process of Alzheimer's rather than just treat the symptoms.
In two clinical trials, aducanumab reduced amyloid plaques by 59% to 71% after 18 months.
However, those studies were stopped early because they did not show that patients taking aducanumab were declining in brain function any slower than patients who were not taking it.
Biogen reevaluated the data from a subset of patients in one trial and found a slight improvement in patients receiving the highest dose.
The FDA decided to approve the drug under what is called accelerated approval, which has a lower standard of evidence than full approval. The FDA said Biogen's data show that reducing amyloid plaques is "reasonably likely to result in clinical benefit."
"This pathway allows FDA to provide patients suffering with a serious disease earlier access to a potentially valuable drug when there is some residual uncertainty about the clinical benefit of the drug," Patrizia Cavazzoni, director of the U.S. Food and Drug Administration's Center for Drug Evaluation and Research, said on a call with reporters.
Patients' groups cheered.
"This approval is a victory for people living with Alzheimer’s and their families," Harry Johns, president and CEO of the Alzheimer’s Association, an advocacy group, said in a statement.
"It is a new day," he said. "This approval allows people living with Alzheimer’s more time to live better. For families it means being able to hold on to their loved ones longer. It is about reinvigorating scientists and companies in the fight against this scourge of a disease. It is about hope."
Not everyone agreed.
"The FDA is saying, 'Never mind the lack of determined effectiveness,'" said Lon Schneider, director of the California Alzheimer’s Disease Center at the University of Southern California.
Reducing plaques is not the same as slowing the patient's decline, he noted. It will be like doctors telling patients, "'You need to be confident (that) because we're knocking down the plaques, you're benefiting.'"
Others were skeptical that Biogen will do a satisfactory follow-up study to show its drug really works.
"Past experience with accelerated approval 'conditions' has been disappointing in a lot of respects," said Harvard Medical School professor Aaron Kesselheim, "with too many cases of 'confirmatory trials' taking too long, still testing surrogate measures rather than real clinical endpoints, and even keeping the drug indication on the labeling when the confirmatory trials are negative."
Other therapies are in the pipeline, and some hope that the FDA's move opens the door to better treatments down the road.
"History has shown us that approvals of the first drug in a new category invigorates the field, increases investments in new treatments and encourages greater innovation," the Alzheimer’s Association's chief science officer, Maria Carrillo, said in a statement.
"While today's approval is an important first step in our ongoing fight against Alzheimer's," the FDA's Cavazzoni said, "it's just that: the first step."