Vorapaxar is a selective antagonist for the protease-activated receptor-1 on platelets that inhibits platelet aggregation by thrombin by a route that is independent of the action of other antiplatelet drugs, such as aspirin and clopidogrel. Study results from a prior major study of vorapaxar in nearly 13,000 patients with non–ST-elevation acute coronary syndrome had shown no efficacy benefit from adding the drug in this patient population and showed a similar increased rate of moderate and severe bleeds and intracranial hemorrhage. At the time these results from the TRACER (Thrombin Receptor Antagonist for Clinical Event Reduction in Acute Coronary Syndrome) trial were reported last November at the American Heart Association annual meeting, experts concluded that, in TRACER, treatment with vorapaxar had failed to balance safety and efficacy, at least with the dosage regimen tested in that study.
The study was sponsored by Merck. Dr. Morrow said that he has received research support from and has served as an unpaid consultant to Merck and to several other drug companies. Dr. O’Gara, Dr. Holmes, and Dr. Antman said that they had no relevant disclosures.