Alzheimer's drug, Eli Lilly's donanemab, can slow disease by a few months, with risks, study finds
The experimental Alzheimer's drug donanemab can modestly slow the worsening of the mind-robbing disease by about four to seven months, researchers reported Monday.
In May, Lilly announced donanemab appeared to work but hadn't yet shared all its findings. On Monday, the full results of the 1,700-person study were published by the Journal of the American Medical Association and presented at the Alzheimer's Association International Conference in Amsterdam.
In the study, people ages 60 to 85 who were in early stages of Alzheimer's either received once-a-month infusions of donanemab or dummy infusions of a placebo for 18 months.
Participants in the donanemab group were switched to receive a placebo if enough amyloid, the nerve-disrupting substance in the brain needed for an Alzheimer's diagnosis, cleared.
The results showed both groups declined during the 18-month study but those given donanemab declined about 22% more slowly. Results also showed the drug appears to work better in earlier stages of the disease.
Is Eli Lilly's donanemab FDA approved?
Eli Lilly and Co. is seeking Food and Drug Administration approval of the drug. If cleared, it would be only the second Alzheimer's treatment convincingly shown to delay the disease — after the recently approved Leqembi from Japanese drugmaker Eisai.
The FDA defines Alzheimer's disease as "an irreversible, progressive brain disorder affecting more than 6.5 million Americans that slowly destroys memory and thinking skills and, eventually, the ability to carry out simple tasks." The medications are meant to slow the progression of the disease for people in early stages; they do not reverse dementia in those with more advanced cases.
"Finally there's some hope, right, that we can talk about," Lilly's Dr. John Sims told reporters Monday at the Alzheimer's conference.
"We don't cure the disease," he said. "Diabetes doesn't have a cure either — it doesn't mean you can't have very meaningful treatments for patients."
How does donanemab work? Are there risks?
Similar to Leqembi, the Eli Lilly drug is designed to target and clear away a sticky protein called beta-amyloid that builds up into brain-clogging plaques that are one hallmark of Alzheimer's. Both are lab-made antibodies administered by IV.
Both drugs also come with a serious safety concern: brain swelling or bleeding that in the Lilly study was linked to three deaths.
About a quarter of donanemab recipients showed evidence of swelling, and about 20% had microbleeds.
Scientists say while these drugs may mark a new era in Alzheimer's therapy, huge questions remain about which patients should try them and how much benefit they'll really notice.
"The modest benefits would likely not be questioned by patients, clinicians or payers if amyloid antibodies were low risk, inexpensive and simple to administer. However, they are none of these," Dr. Eric Widera of the University of California, San Francisco, wrote in a JAMA editorial accompanying Lilly's new data.
In a separate editorial, also published in JAMA, Drs. Gil D. Rabinovici and Renaud La Joie of the University of California, San Francisco, say the latest research shows "the field is making steady progress and gaining momentum in the fight against [Alzheimer's]." But they also note, "development of more impactful and safer treatments is still needed."