https://www.scientificamerican.com/article/reassessment-of-alzheimers-drug-raises-hope-and-concerns/

Pharmaceutical giant Biogen now admits that it made a mistake back in March when it stopped a pair of trials of an experimental Alzheimer’s drug. A deep analysis of the data, released Thursday, suggests the drug, called aducanumab, did make a difference for patients who took the highest dose for the longest period of time—but only in one of two studies.

Earlier results were muddied by the discontinuation of both studies after initial data suggested the drug failed to offer significant benefit and by unintended differences between the trials, which were meant to be identical. In a news conference on Thursday, Biogen  vice president Samantha Budd Haeberlein explained that more patients in the successful trial took the highest dose of the drug for longer.