A set-back in Pfizer's quest to expand the use of its cancer drug Ibrance.
Late-stage clinical trials failed to meet the desired goal of increasing the amount of time early-stage breast cancer patients survived without the cancer returning, the company said on Friday.
An independent data monitoring committee warned back in May of the drug's shortfall.
Th drug is already approved in the U.S. to treat certain adult patients with advanced breast cancer that has spread to other parts of the body.
The trial results put Ibrance at a relative disadvantage to a rival drug made by Eli Lilly, which has shown promising signs of reducing the risk of early-stage breast cancer from returning.
Shares of Pfizer were down slightly on the news.