NEW YORK - In a small clinical trial, an experimental Alzheimer's drug slowed the rate at which patients lost the ability to think and care for themselves, drug maker Eli Lilly has announced.
The findings have not been published in any form and have not been widely reviewed by other researchers.
If accurate, it is the first time a positive result has been found in a so-called Phase 2 study, said Dr Lon S. Schneider, a professor of psychiatry, neurology and gerontology at the University of Southern California.
Other experimental drugs against Alzheimer's were never tested in Phase 2 trials, moving straight to larger Phase 3 trials, or failed to produce positive results.
The Phase 3 studies themselves have repeatedly had disappointing results.
The two-year study involved 272 patients with brain scans indicative of Alzheimer's disease. Their symptoms ranged from mild to moderate.
The drug, donanemab, a monoclonal antibody, binds to a small part of the hard plaques in the brain made of a protein, amyloid, that are hallmarks of Alzheimer's disease. Patients received the drug by infusion every four weeks.
Participants who received the drug had a 32 per cent deceleration in the rate of decline, compared with those who got a placebo.
In six to 12 months, plaques were gone and stayed gone, said Dr Daniel Skovronsky, the company's chief scientific officer.
At that point, patients stopped getting the drug - they got a placebo instead - for the rest of the study.
The small study needs to be replicated, noted Dr Michael Weiner, a leading Alzheimer's researcher at the University of California, San Francisco.
Still, "this is big news", he said.
"This holds out hope for patients and their families."
Eli Lilly did not release the sort of pertinent data needed for a thorough analysis, Dr Schneider said.
For example, the company provided only percentages describing declines in function among the participants, not the actual numbers.
Eli Lilly will provide that data at a subsequent meeting and in an article in a medical journal, Dr Skovronsky said.
He said the company would be talking to the United States Food and Drug Administration and regulatory authorities in other countries about helping patients gain access to the drug.
"Certainly the data are exciting," he said. "But we will have to see what the regulators say."