Bleeding risk clouds Merck's hopes for vorapaxar franchise

Vorapaxar isn't shaping up to be the mega hit that Merck ($MRK) had hoped for. Once billed as a promising successor to warfarin, Merck was left to explain marginal benefits and a serious added risk of bleeding for patients. And some analysts were left to speculate that the drug may never make it to the hands of sales reps.

Dr. David Morrow of Brigham and Women's Hospital in Boston told the gathering at the American College of Cardiology that 11.2% of the patients taking vorapaxar experienced a cardiovascular event, such as heart attack, stroke or death, compared to 12.4% of the patients in the control arm. Here's the killer, though: 4.2% of patients taking vorapaxar experienced moderate or severe bleeding, compared to 2.5% in the control arm receiving standard of care plus a placebo.

The investigators zeroed in on a large group of patients with a history of heart attack, tracking a net benefit that could open a path to an approval. Now Merck has to decide for itself where it takes the program from here. 

Merck knew that it had a problem on its hands at the beginning last year, when troubling safety data forced investigators to stop using the drug to treat patients with a history of stroke. But despite the mixed results and continued problems with bleeding, Merck--which paid $41 billion for Schering-Plough in part to get its hands on the drug--still sees the glass more half full than half empty.

"We are extremely excited by the results," Francis Plat, Merck's head of cardiovascular clinical research, told Reuters. "This is a positive trial." Some analysts, though, have already zeroed out any expected earnings from the pill.

- get the press release
- read the Reuters story
- here's the AP report