The experimental Alzheimer’s disease drug lecanemab slowed the progression of cognitive decline by 27 percent in a large, late-stage clinical trial, the drugmakers Biogen and Eisai said.
Lecanemab is in a family of medicines designed to clear the brain of plaques formed by the buildup of a protein known as beta-amyloid, which is thought to play a role in the development of Alzheimer’s disease. In clinical trial results released by Biogen and Eisai on September 27, lecanemab also reduced amyloid levels in the brain and appeared to improve participants’ cognition and ability to perform daily tasks.
“Today’s announcement gives patients and their families hope that lecanemab, if approved, can potentially slow the progression of Alzheimer’s disease, and provide a clinically meaningful impact on cognition and function,” said Michel Vounatsos, the chief executive officer at Biogen, in a statement releasing some of the drug's trial results. “Importantly, the study shows that removal of aggregated amyloid beta in the brain is associated with a slowing of disease in patients at the early stage of the disease.”
For the trial, researchers randomly assigned almost 1,800 people with early Alzheimer’s disease to receive biweekly infusions of lecanemab or a placebo solution for 18 months. The trial included people with a wide range of chronic health problems such as obesity, diabetes, and high blood pressure — reflecting the real-life circumstances of many Alzheimer’s disease patients.
By the end of the study period, lecanemab reduced the decline in cognitive test scores by 27 percent more than placebo infusions. Researchers saw a statistically meaningful difference in cognitive scores with lecanemab starting after about six months of treatment.
Overall, 2.8 percent of trial participants who took lecanemab experienced symptoms from swelling in the brain, a side effect known as amyloid-related imaging abnormalities-edema/effusion (ARIA-E). None of the participants on placebo had these symptoms.
Symptoms of another side effect called ARIA-H, which involves iron accumulation in tissue and brain bleeding, occurred in 0.7 percent of people on lecanemab and 0.2 percent of those on the placebo.
These new clinical trial results for lecanemab haven’t yet been published in a medical journal or independently reviewed. But they offer some of the strongest evidence to date that targeting the accumulation of amyloid in the brain might ease Alzheimer’s disease symptoms.
“The combination of the biomarker change — reduced amyloid — plus slowing of cognitive decline in this study is encouraging news for the 57 million patients around the world living with Alzheimer’s,” said Howard Fillit, MD, the cofounder and chief science officer at the Alzheimer’s Drug Discovery Foundation, in a statement.
“However, amyloid-clearing drugs will provide an incremental benefit at best and there is still a pressing need for the next generation of drugs focused on other targets based on our knowledge of the biology of aging," he said.
Biogen won U.S. regulatory approval for the first amyloid-clearing drug, Aduhelm, in 2021 under an accelerated process that required additional testing because it didn’t show a clear clinical benefit. Earlier this year, Medicare, the U.S. health program for people 65 and older, limited coverage of Aduhelm to patients in clinical trials, citing a lack of definitive proof that it improves symptoms.
In July 2022, Eisai asked the U.S. Food and Drug Administration (FDA) to approve lecanemab under the same accelerated review process. On the basis of the new clinical trial results, Eisai said it now plans to seek traditional FDA approval for lecanemab by March 2023.