Biogen Hits High on Positive Test Results

Biogen Idec Inc. BIIB shares surged $29.60, or 6.8% in mid-morning trade Friday, to $463.25 U.S. -- a new 52-week high -- after the company reported positive data from an early study of an investigational Alzheimer's disease treatment.

The Phase 1b study of the drug called aducanumab showed positive results in patients with mild Alzheimer's, Biogen said in a statement.

The drug reduced amyloid plaque in the brain, which is believed to play a key role in creating the symptoms of the disease.

Biogen is planning to advance to a Phase 3 trial later this year. Shares have gained 20% in the last three months, while the S&P 500 has gained about 1%.

Biogen's 52-week low was $272.02 U.S., dating back to last April 15.