Biogen Inc. laid out more data Thursday on its experimental Alzheimer's drug, raising no major safety alarms but also offering little compelling evidence that the drug, once declared a failure, actually works.

Experts had been watching closely for any statistical abnormalities or excess safety issues that would affect how the drug is reviewed by the U.S. Food and Drug Administration (FDA). If approved, aducanumab would be the first treatment designed to delay progression of the fatal, mind-robbing disease for millions of patients.

Biogen's fairly neutral showing, and supportive comments from a panel of experts chosen by the company, buoyed investor hopes that the treatment has a reasonable shot at approval. Shares in the company rose more than 3 percent.