Drug developers are working on treatments for Alzheimer’s disease, which is one of the leading causes of dementia.
Alzheimer’s Treatment
Only five months after the US Food and Drug Administration (FDA) granted “accelerated” approval for lecanemab, a drug developed by Biogen and Eisai to treat Alzheimer’s disease, another pharmaceutical company, Eli Lilly, has released “positive results” from phase 3 trials for its own candidate Alzheimer’s treatment, donanemab.
Donanemab, according to a press release issued on May 3, “significantly slowed cognitive and functional decline in people with early symptomatic Alzheimer’s disease.”
Because Eli Lilly has yet to publish the full results, the data has not been peer-reviewed or independently verified, and experts can only comment on the press release.
The Alzheimer’s Association’s chief science officer, Maria Carrillo, stated in the United States, “These are the strongest phase 3 data for an Alzheimer’s treatment to date.”
The news has also been welcomed by Alzheimer Europe.
However, Derek Lowe, a drug discovery expert, wrote in the journal Science that “we are surely looking at the most optimistic take possible — we’ll have to wait for filing with the FDA to see more.”
Eli Lilly says it plans to present its findings at a conference in July and to submit the drug to the FDA around the same time.
Goal is to treat Alzheimer’s disease and other forms of dementia
At least 55 million people worldwide are affected by Alzheimer’s disease. Alzheimer’s disease is the most common type of dementia, according to the World Health Organization, and “dementia is the seventh leading cause of death and one of the major causes of disability and dependency among older people globally.”
Dementia is one of the most difficult conditions to treat. As a result, pharmaceutical companies are known to discontinue research when it is unprofitable and their chances of success are slim.
However, there is a renewed push to find Alzheimer’s treatments. The goal of the United States’ National Alzheimer’s Disease Plan is to “prevent and effectively treat Alzheimer’s disease by 2025.”
The FDA states that it “may approve drugs for serious conditions where there is an unmet medical need,” which explains lecanemab’s quick approval, but this does not imply that the FDA lowers its standards in such cases.
The FDA denied Eli Lilly’s request for accelerated approval of donanemab in January. The FDA stated that it required more patient safety data.
Donanemab: How Does It Work?
Donanemab is not the first medication of its kind. Donanemab, like other antibody-based therapies such as lecanemab, is not a cure for Alzheimer’s.
Instead, they are antibodies that target various forms of amyloid-beta (A) proteins, which can clump together to form amyloid plaques in people’s brains, causing cognitive decline.
The medication is designed to remove plaques from the brain and slow the progression of the disease.
“Nearly half (47%) of participants on donanemab, compared to 29% on placebo, had no clinical progression at 1 year,” according to the Eli Lilly press release. “[The drug] resulted in a 40% reduction in the ability to perform daily activities.”
A placebo is a non-active substance used to compare results with an active substance (the one being tested).
How Does Donanemab Differ From Lecanemab?
According to Eli Lilly’s press release, donanemab slows cognitive decline by 35%. The results of the Lecanemab trial showed that it slowed cognitive decline by 27%.
Both drugs are administered intravenously, but the doses differ: donanemab was administered every four weeks, while lecanemab was administered every two weeks.
Both drugs have only been tested on people in the early stages of Alzheimer’s disease. As a result, it is unclear how effective the drugs are for people with more advanced forms of the disease.
Lecanemab is approved in the United States, but it is still being evaluated by the European Medicines Agency (EMA), the FDA’s European counterpart. Donanemab was not approved for use in the United States or Europe at the time of writing.
Three people were killed in the Donanemab Trials
Both donanemab and lecanemab have a high risk of side effects, according to a May 4 news article published in the journal Nature.
The side effects include “amyloid-related imaging abnormalities” — or ARIA — such as brain swelling or bleeding.
Eli Lilly reported brain swelling in 24% of trial participants and brain bleeding in 31% of trial participants. According to the company, three patients died as a result of these side effects.
“The majority of ARIA cases were mild to moderate in severity and were resolved or stabilized with appropriate management,” the company stated. The prevalence of severe ARIA was 1.6%.
“ARIA is usually asymptomatic,” said Frank Jessen, director of the Clinic and Polyclinic for Psychiatry and Psychotherapy at the University of Cologne in Germany.
Lecanemab’s phase 3 results revealed that 17% of participants experienced brain bleeds and 13% experienced brain swellings, which was lower than donanemab. However, Biogen and Eisai, the companies behind lecanemab, have reported three deaths linked to the drug.
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