Shares of the company, which posted fourth-quarter sales that narrowly missed estimates, were up marginally at $62.25 in premarket trading on Thursday. U.S. sales of Keytruda picked up substantially, likely benefiting from the U.S. Food and Drug Administration's approval in October for use as an initial therapy for lung cancer. Bristol-Myers Squibb & Co , which was the first to market potentially game-changing drugs that spur the immune system to fight cancer, was long perceived as the industry leader in immuno-oncology, with Merck hot on its heels and AstraZeneca Plc and Roche Holding AG playing catch-up.