Drugmakers Biogen and Eisai say their experimental drug lecanemab slowed the progress of Alzheimer’s disease in a large human study the companies did. The results could mean a rare victory in a field filled with failed experiments to find an effective treatment for the disease. The companies said early results showed that the treatment reduced cognitive loss by 27 percent when compared to a placebo, an inactive substance. The 18-month-long study involved 1,800 subjects. All had been identified with early-stage Alzheimer’s. The patients were measured for mental decline and their ability to do daily activities like putting on clothes and feeding themselves. Dr. Jeff Cummings is the director of the Chambers-Grundy Center for Transformative Neuroscience at the University of Nevada Las Vegas. The expert told Reuters, If you can slow a disease by almost 30 percent, that's fantastic. Expert Ronald Petersen also praised the findings. It's not a huge effect, but it's a positive effect, he said. Peterson directs the Mayo Clinic Alzheimer's Disease Research Center in Rochester, Minnesota. A statement from the Alzheimer’s Association called the findings the most hopeful to date for possible treatments of the disease causes. Eisai said it would discuss the full results from the study in late November. It also plans to publish findings in a medical publication. And the company said it is seeking quick approval for the drug in the United States, Japan and Europe by early next year.