Drugmaker Pfizer Inc. said Monday that a midstage study of its experimental drug for advanced breast cancer, palbociclib, met the main goal.
The world's second-biggest drugmaker said the drug, combined with another medicine called letrozole, increased the time patients survived without tumors growing, compared with women just getting letrozole.
Shares of New York-based Pfizer jumped more than 4 percent early on and closed trading up 21 cents at $30.61 while the broader markets fell sharply.
Analysts are closely watching palbociclib, which is for postmenopausal women with certain tumor characteristics found in about 60 percent of patients with advanced breast cancer. It's seen as a potential huge seller.