Merck clears an FDA panel with its clot-fighting vorapaxar

Merck ($MRK) is marching toward FDA approval for one of its more promising cardio drugs, convincing a panel of agency advisers to recommend the clot-busting vorapaxar to help prevent second events in patients who have already endured heart attacks.

The panel voted 10-1 that vorapaxar's benefits outweighed its risks in Merck's targeted population, which leaves out patients who have suffered strokes because of some potential bleeding issues. The drug is a first-in-class inhibitor of PAR-1, stopping the receptor from interacting with thrombin and thus halting the formation of blood clots, Merck said.

The well-traveled treatment was a key aspect of Merck's $41 billion deal for Schering-Plough back in 2009, when many believed the drug could carve out a blockbuster future by beating out warfarin. Three years later, however, serious bleeding risks came to light, leading Merck to leave out patients with history of stroke or transient ischemic attack and thereby trim some of vorapaxar's potential market.

Still, Merck believes it has a winner on its hands. There are about 7.6 million Americans who have suffered a heart attack, Cardiovascular Vice President Daniel Bloomfield said, and about 190,000 have a recurrent episode, creating a serious unmet need.

"The results of today's advisory committee mark an important milestone in our effort to bring vorapaxar to appropriate patients with a history of heart attack," Bloomfield said in a statement. "We look forward to working with the FDA as it completes its review."

The agency is not bound to follow the recommendations of its panels, though it generally does, especially when votes verge on unanimity. If vorapaxar wins approval, Merck will market the drug as Zontivity.

- read the statement