Vorapaxar and Lower Extremity Bypass Grafts

A Double-blind, Randomized, Parallel Design Two Center Study to Compare the Effect of Vorapaxar vs. Placebo on Lower Extremity Vein Graft Maturation, Remodeling, and Function

There are no medical therapies indicated for reduction of limb ischemic events. Studies of dual-antiplatelet therapy with aspirin and clopidogrel versus aspirin alone (CASPAR) as well as studies of systemic anticoagulation (WAVE) have shown no benefit for either strategy in the reduction in limb vascular events. Surgical bypass grafting involves harvesting of the vein, warm ischemia with disruption of vaso vasorum, ischemia-reperfusion, and finally heightened hemodynamic stress in the new arterial environment. Vein grafts rapidly remodel in response to the increase in blood flow and pressure in an attempt to normalize them into physiological range. The investigators have previously identified 3 distinct temporal phases of the remodeling process: During the first 30 days following implantation is a critical period of luminal enlargement which appears to be an endothelium-independent process. The second phase occurs between 1 and 3 months and represents a period of stiffening of the vein graft indicating synthesis of fibrous proteins. The third period is referred to as biochemical remodeling wherein the vein recovers clinically measureable endothelial function. It is likely diabetes mellitus impacts each of these phases. TRA2°P-TIMI 50 demonstrated a reduction in acute limb ischemic (ALI) events (42% reduction) and urgent peripheral arterial revascularizations (35% reduction), a finding unique among medical therapies. While the temporal trend in reduction in ALI events occurred early and late after exposure suggestion an antithrombotic mechanism, the reduction in elective revascularization occurred later suggested beneficial effects beyond platelet inhibition. The purpose of this trial is to study the physiological impact of vorapaxar on lower extremity bypass graft maturation and function.

Study Overview

• Status: Withdrawn
• Conditions: Peripheral Artery Disease
• Intervention / Treatment: Drug: Vorapaxar; Drug: Placebos

Detailed Description

Peripheral artery disease (PAD) is characterized by atherosclerotic occlusive disease of the lower extremities. More than 8 million Americans and 200 million people globally have PAD. Recent data reveal a prevalence of 15% in the MEDICARE population. In populations at risk, patients with a history of diabetes or cigarette smoking, the risk may rise as high as 30%. In addition to the heightened risk of myocardial infarction and stroke, PAD increases the risk of lower extremity claudication and critical limb ischemia. Lower extremity bypass grafting is an important method of restoring blood flow to the distal limb, reducing symptoms of claudication, and preventing amputation in patients with severe PAD.

Vorapaxar is a protease activated receptor (PAR)-1 antagonist that inhibits thrombin activation of the PAR-1 receptor. Vorapaxar has been FDA approved for patients with PAD to reduce the rate of cardiovascular death, MI, stroke, and urgent coronary revascularization. It is prohibited in patients with a previous stroke. In addition, patients treated with vorapaxar were noted to have a significant reduction in the rates of acute limb ischemia. This study will be a randomized, double blind, placebo-controlled randomized study of vorapaxar vs. placebo in 80 patients undergoing femoral-popliteal bypass grafting for Rutherford 3 - 5 disease.

Baseline visit: Informed consent will be signed. Vital signs will be taken and blood drawn fasting for baseline values.

First visit, pre-surgery: Blood will be drawn for platelet activation testing. A 6 minute walk test will be performed. Brachial artery reactivity testing will be performed. An ankle-brachial index will be performed.

30 days: Platelet testing will be performed. 90 days: Limited history and physical exam. 180 days: Limited history and exam, blood draw for biomarkers, brachial artery reactivity testing. Vein bypass graft reactivity testing.

360 days: 6 minute walk test and ankle brachial index will be performed.

Randomization: The Investigational Pharmacy will create a block randomization. Patients in the active treatment group will receive vorapaxar 2.08 mg daily or matching placebo. Treatment will continue for 1 year.

In addition, 20 healthy subjects to serve as a control population to define normal parameters during a single visit day. The healthy subjects will not be administered vorapaxar or placebo.

• Study Type: Interventional
• Phase: Phase 4

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: 35 years to 75 years (Adult, Older Adult)
• Accepts Healthy Volunteers: No
• Genders Eligible for Study: All

Description

Inclusion Criteria:

• Male or female, age 35 years or older
• Atherosclerotic, infrainguinal PAD
• Rutherford classes 3-5 planned for lower extremity bypass grafting
• Adequate inflow into the index femoral artery
• Adequate popliteal, tibial, or pedal revascularization target
• Willing to comply with protocol, attend follow-up appointments, complete all study assessments, and provide informed consent

Exclusion Criteria:

• Complete occlusion of the iliac artery
• Aortoiliac occlusive disease or severe common femoral artery disease
• Presence of a femoral, popliteal or tibial aneurysm of the index limb
• Life expectancy less than 2 years
• A vascular disease prognosis that includes an anticipated above ankle amputation on index limb within 4 weeks of index procedure
• Renal dysfunction defined as MDRD eGFR ≤ 30ml/min/173 m2 at the time of screening
• Currently on dialysis or history of a renal transplant
• A documented hypercoagulable state
• Nonatherosclerotic occlusive disease
• Any prior infrainguinal revascularization
• Current immunosuppressive medication, chemotherapy or radiation therapy
• Absolute contraindication to iodinated contrast
• Women who are pregnant
• Women who are nursing

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Other
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

2

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Active Comparator: Experimental: Vorapaxar; Drug: Vorapaxar 2.08 mg orally daily for a year Other name: Zontivity	Drug: Vorapaxar; 2.08 mg oral tablet daily; Other Names: Zontivity
Placebo Comparator: Placebo Comparator: Placebos; Medication: Matching Placebo Daily tablet	Drug: Placebos; Placebo oral tablet daily; Other Names: Placebo

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Bypass Graft Flow Mediated Vasodilation under Fasted Conditions using B-mode ultrasonography on Day 180 for each treatment condition.	Ultrasonographic evaluation of the graft before and after sphygmomanometric cuff inflation on the calf is performed and the measure of interest is percent increase in vein graft diameter.	6 Months

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change From Baseline in Flow Mediated Vasodilation (FMD) Under Fasted Condition on Day 180 [ Time Frame: baseline and day 180 for each treatment arm ]	Ultrasonographic evaluation of the graft before and after sphygmomanometric cuff inflation on the arm is performed and the measure of interest is percent increase in brachial artery diameter.	6 Months
Platelet Activation blood testing	The investigators will be measuring levels of platelet dilysyl-MDA cross-links 30 days after treatment initiation. Higher levels indicate more platelet activation.	30 days
Change in Six Minute Walk Test from Baseline to 1 year	The distance walked in a 100 foot hallway in 6 minutes.	One year

Collaborators and Investigators

• Sponsor: Vanderbilt University
• Collaborators: Merck Sharp & Dohme LLC
• Investigators: Principal Investigator: Joshua A Beckman, Vanderbilt University Medical Center

Study record dates

Study Major Dates

• Study Start (Actual): October 1, 2017
• Primary Completion (Actual): January 10, 2018
• Study Completion (Actual): January 10, 2018

Study Registration Dates

• First Submitted: November 18, 2016
• First Submitted That Met QC Criteria: November 22, 2016
• First Posted (Estimate): November 29, 2016

Study Record Updates

• Last Update Posted (Actual): January 25, 2018
• Last Update Submitted That Met QC Criteria: January 23, 2018
• Last Verified: January 1, 2018

More Information

Terms related to this study

• Keywords: Atherosclerosis
• Additional Relevant MeSH Terms: Cardiovascular Diseases; Vascular Diseases; Arteriosclerosis; Arterial Occlusive Diseases; Atherosclerosis; Peripheral Vascular Diseases; Peripheral Arterial Disease; Platelet Aggregation Inhibitors; Vorapaxar
• Other Study ID Numbers: 161925

Plan for Individual participant data (IPD)

• Plan to Share Individual Participant Data (IPD)?: No
• IPD Plan Description: There is no plan to share IPD at this time.

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No
• product manufactured in and exported from the U.S.: No