The Absence of a Clinically Significant Effect of Food on the Single Dose Pharmacokinetics of Vorapaxar, a PAR-1 Antagonist, in Healthy Adult Subjects

Protease-Activated Receptor Antagonist for Reducing Cardiovascular Events - A Review on Vorapaxar

Acute Coronary Syndrome (ACS) is a term that describes pathologies related to myocardial ischemia, and is comprised of unstable angina, non-ST elevation myocardial infarction, and ST elevation myocardial infarction. Urgent management of ACS is typically necessary to prevent future morbidity and mortality. Current medical recommendations of ACS management involve use of dual antiplatelet therapy, typically with aspirin and clopidogrel. However, newer therapies are being designed and researched to improve outcomes for patients with ACS. Vorapaxar is a novel antiplatelet therapy that inhibits thrombin-mediated platelet aggregation to prevent recurrence of ischemic events. It has been Food and Drug Administration approved for reduction of thrombotic cardiovascular events in patients with a history of MI or peripheral arterial disease with concomitant use of clopidogrel and/or aspirin, based upon the findings of the TRA 2°P-TIMI 50 trial. However, Vorapaxar was also found to have a significantly increased risk of bleeding, which must be considered when administering this drug. Based upon further subgroup analysis of both the TRA 2°P-TIMI 50 trial and TRACER trial, Vorapaxar was found to be potentially beneficial in patients with peripheral artery disease, coronary artery bypass grafting, and ischemic stroke. There are current trials in progress that are further evaluating the use of Vorapaxar in those conditions, and future research and trials are necessary to fully determine the utility of this drug.

Exploring the Relationship of Drug BCS Classification, Food Effect, and Gastric pH-Dependent Drug Interactions

Food effect (FE) and gastric pH-dependent drug-drug interactions (DDIs) are both absorption-related. Here, we evaluated if Biopharmaceutics Classification System (BCS) classes may be correlated with FE or pH-dependent DDIs. Trends in FE data were investigated for 170 drugs with clinical FE studies from the literature and new drugs approved from 2013 to 2019 by US Food and Drug Administration. A subset of 38 drugs was also evaluated to determine whether FE results can inform the need for a gastric pH-dependent DDI study. The results of FE studies were defined as no effect (AUC ratio 0.80-1.25), increased exposure (AUC ratio ≥1.25), or decreased exposure (AUC ratio ≤0.8). Drugs with significantly increased exposure FE (AUC ratio ≥2.0; N=14) were BCS Class 2 or 4, while drugs with significantly decreased exposure FE (AUC ratio ≤0.5; N=2) were BCS Class 1/3 or 3. The lack of FE was aligned with the lack of a pH-dependent DDI for all 7 BCS Class 1 or 3 drugs as expected. For the 13 BCS Class 2 or 4 weak base drugs with an increased exposure FE, 6 had a pH-dependent DDI (AUC ratio ≤0.8). Among the 16 BCS Class 2 or 4 weak base drugs with no FE, 6 had a pH-dependent DDI (AUC ratio ≤0.8). FE appears to have limited correlation with BCS classes except for BCS Class 1 drugs, confirming that multiple physiological mechanisms can impact FE. Lack of FE does not indicate absence of pH-dependent DDI for BCS Class 2 or 4 drugs. Graphical Abstract.

Vorapaxar: The Current Role and Future Directions of a Novel Protease-Activated Receptor Antagonist for Risk Reduction in Atherosclerotic Disease

Introduction

Despite the current standard of care, patients with cardiovascular disease remain at a high risk for recurrent events. Inhibition of thrombin-mediated platelet activation through protease-activated receptor-1 antagonism may provide reductions in atherosclerotic disease beyond those achievable with the current standard of care.

Objective

Our primary objective is to evaluate the clinical literature regarding the role of vorapaxar (Zontivity™) in the reduction of cardiovascular events in patients with a history of myocardial infarction and peripheral artery disease. In particular, we focus on the potential future directions for protease-activating receptor antagonists in the treatment of a broad range of atherosclerotic diseases.

Data Sources

A literature search of PubMed and EBSCO was conducted to identify randomized clinical trials from August 2005 to June 2016 using the search terms: ‘vorapaxar’, ‘SCH 530348’, ‘protease-activated receptor-1 antagonist’, and ‘Zontivity™’. Bibliographies were searched and additional resources were obtained.

Results

Vorapaxar is a first-in-class, protease-activated receptor-1 antagonist. The Thrombin Receptor Antagonist for Clinical Event Reduction (TRACER) trial did not demonstrate a significant reduction in a broad primary composite endpoint. However, the Thrombin-Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events (TRA 2°P-TIMI 50) trial examined a more traditional composite endpoint and found a significant benefit with vorapaxar. Vorapaxar significantly increased bleeding compared with standard care. Ongoing trials will help define the role of vorapaxar in patients with peripheral arterial disease, patients with diabetes mellitus, and other important subgroups. The use of multivariate modeling may enable the identification of subgroups with maximal benefit and minimal harm from vorapaxar.

Conclusion

Vorapaxar provides clinicians with a novel mechanism of action to further reduce the burden of ischemic heart disease. Identification of patients with a high ischemic risk and low bleeding risk would enable clinicians to maximize the utility of this unique agent.

Electronic supplementary material

The online version of this article (doi:10.1007/s40268-016-0158-4) contains supplementary material, which is available to authorized users.

No Pharmacokinetic Drug-Drug Interaction Between Prasugrel and Vorapaxar Following Multiple-Dose Administration in Healthy Volunteers

Vorapaxar is a first-in-class antagonist of the protease-activated receptor-1, the primary thrombin receptor on human platelets, which mediates the downstream effects of thrombin in hemostasis and thrombosis. Prasugrel is a platelet inhibitor that acts as a P2Y12 receptor antagonist through an active metabolite, R-138727. This study investigated the interaction of these 2 platelet antagonists when coadministered. This was a randomized, open-label, multiple-dose study in 54 healthy volunteers consisting of a fixed-sequence crossover and a parallel group design. In sequence 1, 36 subjects received prasugrel 60 mg on day 1 and then prasugrel 10 mg once daily on days 2 to 7, followed by vorapaxar 40 mg and prasugrel 10 mg on day 8 and then vorapaxar 2.5 mg and prasugrel 10 mg orally once daily on days 9 to 28. In sequence 2, 18 subjects received vorapaxar 40 mg on day 1 and then vorapaxar 2.5 mg once daily on days 2 to 21. The geometric mean ratios (90% confidence intervals) for AUCτ and C_max of coadministration/monotherapy for vorapaxar (0.93 ng·h/mL[0.85-1.02 ng·h/mL] and 0.95 ng/mL [0.86-1.05 ng/mL]) and R-138727 (0.91 ng·h/mL [0.85- 0.99 ng·h/mL] and 1.02 ng/mL [0.89-1.17 ng/mL]) were within prespecified bounds, demonstrating the absence of a pharmacokinetic interaction between vorapaxar and prasugrel. There was no specific safety or tolerability risk associated with multiple-dose coadministration of vorapaxar and prasugrel. In conclusion, in this study in healthy volunteers, there was no pharmacokinetic drug-drug interaction between vorapaxar and prasugrel. Multiple-dose coadministration of the 2 drugs was generally well tolerated.

Impact of selective platelet inhibition in reducing cardiovascular risk - role of vorapaxar

This article reviews the pharmacology, clinical efficacy, and safety of vorapaxar in reducing cardiovascular risk. Vorapaxar is a tricyclic himbacine-derived reversible inhibitor of platelet surface protease activator receptor-1, which prevents thrombin from activating platelets. Two Phase III clinical trials and multiple subanalyses from the two trials with vorapaxar have been published. In patients with recent acute coronary syndrome, vorapaxar, when added to standard therapy, did not reduce the composite cardiovascular end point. In contrary, in a study of secondary prevention for patients with cardiovascular diseases, vorapaxar reduced the risk of cardiovascular death or ischemic events (myocardial infarction, stroke) in patients with stable atherosclerosis who were receiving standard therapy. Vorapaxar is approved in the US for use with aspirin and/or clopidogrel in the secondary prevention of thrombogenic cardiovascular events in stable patients with peripheral arterial disease or a history of myocardial infarction. Vorapaxar increases risk of bleeding and is contraindicated in patients with previous cerebrovascular events. It is essential to balance individual patient’s bleeding risk to any further cardiovascular benefits that they may get. Future investigation is also needed to evaluate use of vorapaxar with newer antiplatelet agents such as ticagrelor and cangrelor, as well as its role as monotherapy.

Vorapaxar: A Protease-Activated Receptor Antagonist for the Prevention of Thrombotic Events

Antiplatelet therapy reduces the risks for cardiovascular morbidity and mortality in patients with atherosclerotic disease, and it is also beneficial in managing peripheral arterial disease (PAD). These agents work through various therapeutic pathways to achieve antithrombotic effects. Although single- or two-drug regimens have been deployed to prevent vascular events, approximately 10% of the patients with acute coronary syndrome remain at risk for recurrent thrombotic events and may need a more aggressive preventative strategy. Vorapaxar offers a unique mechanism for platelet inhibition via the antagonism of protease-activated receptor-1. It is approved for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction (MI) or PAD. This new drug approval was mainly based on the results from subgroup analyses from a large landmark trial (Thrombin Receptor Antagonist in Secondary Prevention of Atherothrombotic Ischemic Events-Thrombolysis in Myocardial Infarction 50), which found that vorapaxar reduces the rate of the combined end point of cardiovascular death, MI, stroke, and urgent coronary revascularization when used in addition to aspirin and/or clopidogrel in patients without a history of stroke. In this study, vorapaxar was discontinued in patients with a history of stroke due to excessive risk for intracranial hemorrhage after 2 years of therapy. As an adjunctive therapy to standard regimens, vorapaxar provides a greater net clinical benefit in MI patients who are at a lower risk for bleeding. In patients with PAD, it reduces the rates of recurrent acute limb ischemia with rehospitalization or peripheral revascularization. The most concerning adverse effect is bleeding. Vorapaxar should not be used in patients with a history of stroke, transient ischemic attack, intracranial hemorrhage, or active pathological bleeding. The risks and benefits of adding vorapaxar to intensify antiplatelet regimens should be assessed in individual patients to aim for additional therapeutic outcomes with minimal bleeding risks.

Vorapaxar: A novel agent to be considered in the secondary prevention of myocardial infarction

Patients receiving therapy for the secondary prevention of myocardial infarction (MI) are still at high risk of a major cardiovascular event or death despite the use of currently available treatment strategy. Vorapaxar, an oral protease-activated receptor antagonist, is a novel antiplatelet drug that has been recently approved to provide further risk reduction. The results of two Phase III trials (thrombin receptor antagonists for clinical event reduction and the TRA 2°P-TIMI 50) have showed that vorapaxar, in addition to standard of care therapy, has the potential to provide further risk reduction in patients with prior MI. A search was made on PubMed on articles related to clinical trials and clinical consideration with the use of vorapaxar. This review article summarizes the results of Phase II trials, Phase III trials, subgroup analysis, precautions, and drug interaction with the use of vorapaxar.

Review of vorapaxar for the prevention of atherothrombotic events

INTRODUCTION

Atherosclerosis is frequently caused by clot blockage of the coronary or peripheral arteries, and may lead to myocardial infarction (MI) or peripheral arterial disease (PAD). Despite advancements in management of atherosclerosis, mortality and ischemic rates remain high. Vorapaxar is a protease activated receptor-1 (PAR-1) antagonist, and prevents thrombin activation of PAR-1 receptors on platelets.

AREAS COVERED

Vorapaxar was studied in 2 landmark trials in patients with acute coronary syndrome (ACS) and in those with history of atherosclerosis. For patients with ACS, vorapaxar did not significantly reduce rates of the primary efficacy outcome as compared to placebo. For patients with a history of atherosclerosis, vorapaxar significantly reduced rates of primacy outcome. However, in both landmark trials, vorapaxar significantly increased risks of bleeding, and significantly increases risks of intracranial hemorrhage in patients with a history of stroke. Vorapaxar was approved in 2014 in the US for patients with a history of MI or PAD, and in the European Union for patients with a history of MI.

EXPERT OPINION

Use of vorapaxar may be limited due to its high potential for causing bleeding. Efficacy of vorapaxar in addition to aspirin and prasugrel or ticagrelor for the management of ACS should be studied in the future.

Vorapaxar: first global approval

Vorapaxar [Zontivity(®) (US)], an orally active protease-activated receptor-1 (PAR-1) receptor antagonist, has been developed by Merck & Co for the reduction of thrombotic cardiovascular events in patients with a history of myocardial infarction (MI) or peripheral arterial disease (PAD). Vorapaxar has received its first global approval for this indication in the US. This article summarizes the milestones in the development of vorapaxar leading to this first approval for the reduction of thrombotic cardiovascular events in patients with a prior MI or PAD.

Vorapaxar in atherosclerotic disease management

OBJECTIVE

To review the pharmacology, efficacy, and safety of vorapaxar, a protease activator receptor-1 (PAR-1) antagonist, in the management of atherosclerotic diseases.

DATA SOURCES

Peer-reviewed clinical trials and review articles were identified from MEDLINE and Current Content database (both 1966 to December 31, 2014) using the search terms vorapaxar and protease activator receptor antagonist.

STUDY SELECTION AND DATA EXTRACTION

A total of 30 clinical studies were identified (16 clinical trials, including subanalyses, 14 related to pharmacology, pharmacokinetics, and pharmacodynamics and drug interactions).

DATA SYNTHESIS

Two phase III clinical trials with vorapaxar have been published. In patients with non-ST segment elevation myocardial infarction (MI), vorapaxar failed to significantly reduce the primary efficacy end point (composite of cardiovascular death, MI, stroke, recurrent ischemia with hospitalization, and urgent coronary revascularization). Conversely, in a study of secondary prevention for patients with cardiovascular disease, the composite end point of cardiovascular death, MI, or stroke was significantly reduced. In both trials, the safety end points of major/minor bleeding were increased compared with placebo. In the secondary prevention trial, an increased incidence of intracranial hemorrhage led to the exclusion of patients with a prior history of stroke.

CONCLUSION

Vorapaxar is approved for use with aspirin and/or clopidogrel in the secondary prevention of cardiovascular events in stable patients with peripheral arterial disease or a history of MI. However, the addition of vorapaxar to other antiplatelets can significantly increase the risk of bleeding. It is, therefore, essential to balance the need for further reduction of risk of thrombotic event with patient's individual bleeding risk.