Improving antiplatelet therapy for atherothrombotic disease - Preclinical and clinical results with SCH 530348, the first oral thrombin receptor antagonist selective for PAR-1

Morbidity and mortality in patients with atherothrombotic disease remain high despite the use of antiplatelet therapy with aspirin and an ADP receptor antagonist. Selective inhibition of the principal protease-activated receptor (PAR)-1 for thrombin, the most potent agonist for platelet activation, represents a promising novel strategy to reduce thrombosis and ischaemic events. SCH 530348, a potent thrombin receptor antagonist (TRA) selective for PAR-1, has been evaluated in preclinical studies, demonstrating complete and sustained inhibition of thrombin/TRAP-induced platelet aggregation without a concomitant increase in the risk of bleeding. Phase 2 studies in patients undergoing non-urgent or urgent PCI showed that treatment with SCH 530348 in addition to the standard of care (aspirin plus an ADP receptor antagonist) is not associated with an increased risk of TIMI bleeding and is well tolerated, with a rate of adverse events comparable to standard therapy alone. These studies also demonstrated that the use of SCH 530348 in combination with aspirin and an ADP receptor antagonist may reduce the incidence of major adverse cardiac events, specifically periprocedural myocardial infarction, vs aspirin plus an ADP receptor antagonist alone. On the basis of these encouraging results, 2 ongoing large phase 3 randomized trials are evaluating the efficacy and safety of SCH 530348 in combination with the standard-of-care therapy in approximate to 35000 patients with NSTE ACS or established atherosclerosis.