By Deena Beasley and Julie Steenhuysen (Reuters) -Eisai Co Ltd and Biogen Inc on Tuesday said their experimental Alzheimer’s drug significantly slowed cognitive and functional decline in a large trial of patients in the early stages of the disease, marking a rare win in a field littered with failed drugs. The drug, lecanemab, slowed progress of the brain-wasting disease by 27% compared with a placebo, meeting the study’s main goal, and potentially offering hope for patients and their families desperate for an effective treatment. Eisai said the results from the 1,800-patient trial prove the lo…