Vorapaxar in the secondary prevention of atherothrombosis

Dual antiplatelet therapy with aspirin, a platelet cyclooxygenase-1 inhibitor and P2Y12 receptor blockers, remains the major drug strategy to prevent ischemic event occurrence in patients with acute coronary syndromes and in patients undergoing coronary stenting, but there some limitations that can be overcome by targeting novel targets. Unlike direct thrombin inhibitors that bind directly to thrombin, targeting the platelet thrombin receptor, protease activated receptor (PAR)-1, may offer a better choice for the attenuation of atherosclerosis progression, thrombus-mediated ischemic events and restenosis without interfering with primary hemostasis. Vorapaxar - a synthetic analogue of himbacine, is a high affinity and highly selective PAR-1 antagonist that can effectively inhibit thrombin-induced platelet aggregation. In the TRACER trial, the addition of vorapaxar to standard therapy in patients with non-stent thrombosis-elevation- acute coronary syndromes did not significantly reduce the primary composite end point occurrence of cardiovascular (CV) death, myocardial infarction (MI), stroke, hospitalization for ischemia, or urgent revascularization, but significantly increased the GUSTO moderate and severe bleeding (p < 0.001) and intracranial hemorrhage (ICH). In the TRA 2°P-TIMI 50 trial, in patients with a history of MI and peripheral arterial disease (PAD) (67% of the total population), the end point of CV death, MI, or stroke was significantly (20%) reduced with vorapaxar whereas GUSTO moderate or severe bleeding was increased (1.5-fold), but not ICH or fatal bleeding and the net clinical outcome favoring the vorapaxar therapy. Based on these favorable results, the FDA approved vorapaxar for the reduction of thrombotic cardiovascular events in patients with prior MI or with PAD for long term therapy. A careful patient selection is needed to balance efficacy versus safety. At this time, patients with high risk for recurrent ischemic event occurrence such as patients with diabetes mellitus and previous MI can be safely treated with vorapaxar for long-term therapy.