Biogen Inc. will ask U.S. drug regulators to approve the company’s experimental Alzheimer’s therapy, reviving the nearly abandoned treatment after a new analysis of data from two failed clinical trials showed promising results.

The company said it made the decision after talking with the Food and Drug Administration, and reviewing data from a set of experimental trials showing that the therapy appeared to help Alzheimer’s patients’ cognitive function and their ability to perform basic tasks.

Biogen surged 22 per cent in trading before the market opened in New York. The Cambridge, Massachusetts-based drugmaker said in a statement that it plans to send its application to the FDA early next year. It is developing the treatment in partnership with Japanese drugmaker Eisai Co.

The gamble by Biogen -- if successful -- would be one of the drug industry’s most dramatic reversals of fortune in decades. In March, the company said a major trial of the drug, aducanumab, had been a failure. The announcement sent Biogen’s shares down by more than 25 per cent and raised questions about the company’s future.

In the new analysis, Biogen looked at data from the two final-stage trials of more than 3,000 patients. A subset of patients treated with the highest dose of aducanumab had what the company said was a statistically significant slowing of decline of cognitive ability and basic activities of daily living.