Biogen’s ‘positive’ Alzheimer’s trial has a problem with small numbers

At a medical conference in Spain, Biogen and partner Eisai presented data on the drug, BAN2401, meant to clear up concerns that its earlier observed benefits were a mirage. But the explanation revealed that BAN2401’s glimmer of promise is based on results from a small subset of patients in an otherwise large trial, which could be difficult to replicate in later studies.