Researchers have been searching for a drug that can slow the progression of dementia for decades, but they have come up empty handed – until now.
A new drug called lecanemab, developed by Eisai and Biogen, has shown to slow the rate of decline in memory and thinking in early stage Alzheimer’s patients. This is the first time a drug has proven effective at changing the trajectory of the disease.
The study involved roughly 1,800 patients with early stage Alzheimer’s disease. According to the results, the cognition of patients taking the drug declined by 27% less than those on a placebo treatment after 18 months. Patients on lecanemab received two infusions of the drug every other week. The drug slows the decline by reducing toxic plaques in the brain that likely contribute to memory and thinking decline.
“This is a historic moment for dementia research, as this is the first phase 3 trial of an Alzheimer’s drug in a generation to successfully slow cognitive decline,” said Dr Susan Kohlhaas, the director of research at Alzheimer’s Research U.K. “Many people feel Alzheimer’s is an inevitable part of aging. This spells it out: if you intervene early, you can make an impact on how people progress.”
However, around a fifth of patients receiving the drug experienced some side effects, including brain swelling or brain bleeding visible on PET scans, but only 3% reported symptomatic side effects.
The results of the clinical trial give credence to what’s known as the “amyloid hypothesis,” which suggests that these sticky plaques seen in dementia patients are responsible for damaging brain cells that contribute to cognitive decline.
Several previous Alzheimer’s drugs tested on dementia patients successfully reduced the presence of these plagues without demonstrating meaningful clinical results, which led some researchers to doubt the amyloid hypothesis.
But the latest development suggests these plaques may play a role in cognitive decline after all.
“This is an unambiguously statistically positive result and represents something of an historic moment when we see the first convincing modification of Alzheimer’s disease. God knows, we’ve waited long enough for this,” said Rob Howard, a professor of old age psychiatry at University College London (UCL).
Eisai and Biogen plan to apply for regulatory approval in the U.S. and Europe by the end of the year. And the drug is likely to be approved for dementia patients based on the results of the latest clinical trial.
Once it gets approved by the FDA, healthcare providers will have to decide whether or how to fund the drug. There is no word yet on how much it will cost. They will also need to determine who is eligible considering the patients included in the study fall just below a commonly used benchmark for dementia progression.
On the 14-point scale used to assess progression, patients taking the drug scored 0.45 higher than those on the placebo treatment, with an Alzheimer’s patient being expected to decline by about 1 point a year.
“The accepted minimum worthwhile difference ranges from 0.5 to 1.0 points, [meaning] that there are going to be some very difficult conversations and decisions in the next weeks and months,” Howard explained.
Administering the drug to some 6.5 million Alzheimer’s patients in the U.S. would be no easy undertaking. Europe is facing similar concerns if the drug is approved. According to a recent survey in the U.K., just one in three psychiatric facilities would be ready to administer the drug within a year, considering it requires two infusions every two weeks.
There are also questions as to whether patients taking the drug will continue to experience benefits after 18 months, which the current data can’t answer.
Eisai is also looking into whether the drug could be used to prevent Alzheimer’s at even early stages. The company is currently recruiting patients with severe risk of dementia but do not yet have symptoms for another clinical trial to answer these questions.
“This will require a radical change in how we deliver our services,” said Prof Jon Schott, the chief medical officer of Alzheimer’s Research U.K. and a professor of neurology at UCL.
“If this is licensed and this gets through Nice [the National Institute for Health and Care Excellence], the demand will be huge. We’re not ready to deliver this at scale and we need to address that now.”