CHICAGO, July 25 (Reuters) - Biogen Inc and partner Eisai Co Ltd said patients with early-stage Alzheimer's disease treated with their experimental drug BAN2401 experienced 30 percent less cognitive decline than patients who got a placebo in a highly anticipated midstage trial.
The second-highest dose of the drug also showed some benefit, but did not meet statistical significance, according to data presented on Wednesday at the Alzheimer's Association International Conference in Chicago.
Analysts prior to the presentation had said a slowing of dementia symptoms by about 20 percent would be a positive signal, and some said even a 15 percent difference would be favorable.
The results, based on traditional statistical methods after 18 months of treatment, followed 12-month results that failed to meet the study's main cognitive decline goal based on a complex predictive Bayesian statistical model.
The BAN2401 trial involved 856 patients with early Alzheimer's disease who had beta amyloid in their brains as confirmed by brain scans. The highest does of 10 mg/kg bi-weekly - one of five doses tested - was given to 161 patients.
Another 253 patients were treated with the second-highest dose of 10 mg/kg monthly, while 247 were in the placebo group.
Reporting by Julie Steenhuysen Editing by Bill Berkrot