The Japanese drugmaker Eisai said Tuesday that its experimental drug for Alzheimer's disease helped slow cognitive decline in patients in the early stages of the illness.
In a phase 3 clinical trial, the drug called lecanemab slowed cognitive decline by 27% after 18 months. The results have not been peer-reviewed and were announced in a news release.
The results may offer renewed hope to Alzheimer s patients after Biogen rolled out its drug, Aduhelm, last year. Biogen and Eisai partnered in the commercialization of the new drug, although Eisai led its development and phase 3 trial.
Outside experts urged caution in interpreting the results.
The results are a first step in the direction of making a significant impact on the disease, said Dr. Ronald Petersen, a neurologist at the Mayo Clinic in Rochester, Minnesota.
Alberto Espay, a neurologist at the University of Cincinnati College of Medicine, said the benefit was small and that it fell below the threshold of what would be meaningful to a patient. He said patients can view this with cautious optimism. The results were based on 1,795 patients randomly assigned to receive either the drug or a placebo every two weeks over the course of 18 months. Cognitive decline was measured using a clinical dementia rating scale that focused on six areas: memory, orientation, judgment and problem solving, community affairs, home and hobbies, and personal care.
Eisai plans to submit the trial data to the Food and Drug Administration for approval by March, as it will present the findings at an Alzheimer s conference in late November.
Eisai's drug is a monoclonal antibody designed to target amyloid plaques, clumps of protein in the brain that are long considered a hallmark of Alzheimer s.
Biogen's drug Aduhelm was shown to reduce amyloid in the brain, but that didn't translate into a slower progression of the disease. That is leading some scientists to shift from amyloid as a cause of Alzheimer's and look at other possibilities.
The single trial won't prove that amyloid is responsible for the decline in mental function seen in patients, Espay said.
Petersen, who is at the Mayo Clinic, said the trial may show that amyloid is one of several components that lead to the progression of the disease.
He said that the trial results were positive for the field. I think it's going to motivate more beneficial research down the road. He also advocated for more research into preventing the disease, noting that the new drug is not a cure by any means. Besides Biogen's drug, all other drugs approved by the FDA for Alzheimer s are aimed at helping symptoms, not actually slowing the progression of the disease, which is the seventh-leading cause of death in the U.S., according to the Centers for Disease Control and Prevention.
Two similar drugs — Roche and Eli Lilly — are expected to release late-stage clinical trial results over the next few months.