US pharma giant Eli Lilly's experimental Alzheimer's drug slowed clinical decline by 35 per cent compared to placebo, and resulted in 40 per cent less decline on the ability to perform activities of daily living, said the company announcing phase-3 trial results.
The drug, donanemab administered intravenously once a month, works by removing plaque build ups in the brain known as amyloid -- a hallmark of Alzheimer's disease.
The phase-3 trial involved more than 1,700 patients with early symptomatic Alzheimer's disease.
Nearly 47 per cent of participants on donanemab showed no decline on a key measure of disease severity at one year (compared to 29 per cent of participants on placebo).
Further, as Donanemab cleared amyloid levels, 52 per cent of participants stopped their course of treatment by one year and 72 per cent by 18 months.
The study also enrolled a smaller number of people with high levels of tau, representing a later stage of disease progression.
A 35 per cent slowing in cognitive and functional decline was seen in the group with intermediate levels of tau, whose disease hadn't progressed as far. When this intermediate group was combined with the group with higher levels of tau, the figure was 22 per cent. The results have not been peer-reviewed or published in a journal.
"This is the first Phase-3 trial of any investigational medicine for Alzheimer's disease to deliver 35 per cent slowing of clinical and functional decline," said Daniel Skovronsky, Lilly's chief scientific and medical officer, in a statement.
Some side effects, and three deaths were also reported in the trial among people taking the drug -- of which two were attributed to adverse events such as brain swelling or microhemorrhages, known as amyloid-related imaging abnormalities or ARIA.
"We are encouraged by the potential clinical benefits that donanemab may provide, although like many effective treatments for debilitating and fatal diseases, there are associated risks that may be serious and life-threatening," said Mark Mintun, group vice-president Neuroscience Research & Development at Lilly.
"We note that these results suggest that people in the early pathological stage of disease could be the most responsive to therapeutics targeting amyloid," he added.
Based on the new results, the company said it aims to seek the US Food and Drug Administration (FDA) approval this year.
The company had filed for accelerated approval with the FDA based on its phase-2 trial. However, the FDA had rejected it in January this year.