The study included 257 patients with early symptomatic Alzheimer’s disease; 131 received donanemab, while 126 received a placebo. The researchers found that donanemab decreased the decline in cognition and daily function in patients with Alzheimer’s by 32% after 76 weeks, compared with those who received a placebo.
Over the course of 18 months, the 32% decline in decline could have a notable impact on Alzheimer’s patients, noted Maria Carrillo, scientific director of the Alzheimer’s Association, who was not involved in the study.
“In 18 months, compared to people who did not receive the drug, these people were decreasing six months more slowly,” said Carrillo. “There are six more months of better cognition, better memories, better pleasant moments with your family.”
Decline was measured using the Integrated Alzheimer’s Disease Assessment Scale, which measures cognitive and functional capacity, such as memory and the ability to perform daily tasks.
Carrillo said the results of the Phase 2 trial are initial, but promising, and represent some of the most robust data on the ability of a single drug to slow the progression of Alzheimer’s disease.
“This has a lot of potential,” added Carrillo. “It could be a first step towards slowing down, or stopping, cognitive decline in these early stages, which would be really transformative for our field.”
The researchers also looked at the drug’s impact on the accumulation of amyloid beta plaque and tau proteins, which are considered to be hallmarks of Alzheimer’s disease.
In 52 weeks, almost 60% of the participants achieved negative amyloid status, which means that their levels were equal to those of healthy people. At the 76th week, amyloid plaque levels – measured in centroids – decreased by 85 centiloids more than in those who received the placebo, the researchers reported.
Patients who reached these low levels of amyloid beta plaque were withdrawn from donanemab and received the placebo.
Mitigating the disease
“Once these participants were eliminated from amyloid in the brain, the drug was withdrawn, and the slowdown still continued,” Carrillo. “This is important because then you don’t have continuous monitoring for any security or adverse events.”
Participants who received donanemab also showed a greater reduction in the overall burden of tau than those who received the placebo.
Carrillo said that this study was the only one that tracked participants for the presence of beta amyloid plaque and tau before entering the study.
Some researchers in the field believe that “if you stop amyloid early enough and slow down this tau, you may be able to slow down Alzheimer’s,” said Carrillo. “This is what this article is trying to show, and it is one of the first times that we have seen this.”
Research on donanemab is still early, and the researchers say that increasingly large trials are needed to determine the drug’s safety and efficacy.
“We are extremely pleased with these positive results for donanemab as a potential therapy for people living with Alzheimer’s disease, the single leading cause of death without treatment that slows the disease’s progression,” Dr. Mark Mintun, vice president of Eli Lilly’s pain and neurodegeneration, said in a January statement announcing the test results. Mintun said additional research underway is aimed at replicating the findings.
No new treatment approved since 2004
The US Food and Drug Administration has not approved a new Alzheimer’s drug since 2004. The experimental Alzheimer’s drug, aducanumab, developed by the pharmaceutical company Biogen and its Japanese partner Eisai, is currently under review by the FDA.
Many of the more promising Alzheimer’s drug candidates target amyloid beta plaques and tau proteins, since their accumulation correlates with the progression of Alzheimer’s disease. The goal with medications like donanemab is not to cure the disease, but to preserve a person’s memory and cognition for longer.
Alzheimer’s disease is the most common form of dementia and currently affects 6.2 million Americans aged 65 and over, according to the Alzheimer’s Association. The Centers for Disease Control and Prevention in the United States says that number is expected to increase to at least 14 million people by 2060.