Eli Lilly and Co on Saturday said its experimental Alzheimer's drug slowed the rate of decline in a measure of cognition and function by 32% compared with a placebo in a mid-stage trial of patients at an early stage of the mind wasting disease.
The drug, donanemab, also showed positive trends that failed to reach statistical significance on a range of secondary trial goals, the company said, providing details for the first time.
The 18-month, 272-patient study showed, for instance, that patients treated with donanemab had a 23% slower rate of decline in a measure known as the Clinical Dementia Rating Scale Sum of Boxes, a tool commonly used to gauge dementia severity.
The ability to carry out activities like dressing and eating is often impacted by Alzheimer's disease, which reduces cognitive ability like memory and language.
Donanemab is an antibody designed to remove clumps of the Alzheimer's-related protein beta amyloid from the brain. It targets a specific type of beta amyloid that Lilly believes can be rapidly cleared, enabling short-term, but durable treatment.
Patients in the study stopped receiving donanemab and were switched to placebo once their brain plaques reached levels seen in healthy people.
Beta amyloid has been a popular target for dozens of experimental Alzheimer's drugs, all of which have failed so far.
Unlike other drugs aimed at alleviating symptoms, Lilly is "thinking about Alzheimer's disease as a pathology of the brain - more like cancer that you treat," said Daniel Skovronsky, Lilly's chief scientific officer.
In the study, the drug provided the most benefit to patients who entered the trial with lower levels of plaque.
A brain swelling side effect, known as ARIA-E, occurred in 27% of trial patients treated with donanemab, the company said.
Skovronsky said the company is continuing to study the drug in a second, 500-patient trial.
The US Food and Drug Administration is expected to decide in June whether to approve aducanumab, an experimental amyloid-targeting drug developed by Biogen Inc that has demonstrated mixed trial results.
The number of Americans living with Alzheimer's is expected to rise to around 13 million by 2050 from more than 6 million currently, according to the Alzheimer's Association.