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Phase 2 Study of the Safety, Tolerability and Pilot Efficacy of Oral Factor Xa Inhibitor Betrixaban Compared to Warfarin (EXPLORE-Xa)

This study has been completed.
Information provided by (Responsible Party):
Portola Pharmaceuticals Identifier:
First received: August 26, 2008
Last updated: July 12, 2017
Last verified: July 2017
Prevention of stroke in patients with atrial fibrillation (AF). Hypothesis: In patients with non-valvular AF, orally administered betrixaban will provide similar or better efficacy and safety than warfarin and it will offer the advantage of not requiring dose adjustments due to INRs outside the target range of 2.0 to 3.0 and a more consistent level of anticoagulation over time.

Condition Intervention Phase
Atrial Fibrillation Drug: betrixaban Drug: Warfarin Phase 2

Study Type: Interventional
Study Design: Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: Quadruple (Participant, Care Provider, Investigator, Outcomes Assessor)
Primary Purpose: Treatment
Official Title: A Phase 2, Randomized, Parallel Group, Dose-Finding, Multicenter, Multinational Study of the Safety, Tolerability and Pilot Efficacy of Three Blinded Doses of the Oral Factor Xa Inhibitor Betrixaban Compared With Open-Label Dose-Adjusted Warfarin in Patients With Non-Valvular Atrial Fibrillation (EXPLORE Xa)

Resource links provided by NLM:

Further study details as provided by Portola Pharmaceuticals:

Primary Outcome Measures:
  • The primary endpoint will be the occurrence of major or clinically relevant non-major bleeding. [ Time Frame: Up to one year ]

Enrollment: 508
Study Start Date: October 2008
Study Completion Date: November 2009
Primary Completion Date: August 2009 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Arm 1: Betrixaban
Betrixaban, 40 mg, orally, once daily for at least 3 months.
Drug: betrixaban
blinded and randomly assigned: 40 mg, 60mg or 80mg doses, orally, once daily for at least 3 months
Experimental: Arm 2: Betrixaban
Betrixaban, 60 mg, orally, once daily for at least 3 months
Drug: betrixaban
blinded and randomly assigned: 40 mg, 60mg or 80mg doses, orally, once daily for at least 3 months
Experimental: Arm 3: Betrixaban
Betrixaban, 80 mg, orally, once daily for at least 3 months
Drug: betrixaban
blinded and randomly assigned: 40 mg, 60mg or 80mg doses, orally, once daily for at least 3 months
Active Comparator: Arm 4: Warfarin
Warfarin will be prescribed by investigators according to the standard of care.
Drug: Warfarin
Warfarin will be prescribed by the investigator according to the standard of care.
Other Names:
  • Coumadin
  • Acenocoumarol

Detailed Description:

To assess the safety and tolerability of betrixaban at doses of 40 mg, 60 mg and 80 mg given orally once a day for at least 3 months compared to dose-adjusted warfarin in patients with non-valvular atrial fibrillation (AF).

This is a Phase 2, exploratory, randomized, parallel group, multicenter, active comparator, dose finding study of patients with documented non-valvular AF. Patients will be randomized (1:1:1:1) to 1 of 4 treatment groups (approximately 125 patients per group) using an IVRS. A dynamic randomization will be used to balance patients by country, concurrent aspirin use (yes or no) and antecedent warfarin (yes or no). The study will be open label for randomization to warfarin versus betrixaban, but the three daily doses of betrixaban, 40 mg, 60 mg or 80 mg, will be double-blind (identical capsules for all three dose levels). The warfarin-treated patients will be managed according to each center's usual clinical routine with INR monitoring and dose-adjustments in order to maintain a target INR of 2.0 to 3.0 at maximum intervals of four weeks. No loading doses or dose titrations will be used for betrixaban. The betrixaban dose should be ingested in the evening (e.g. at bedtime), preferably at least 2 hours after the evening meal. Note: acenocumerol may be substituted for warfarin as indicated by local practice.


Ages Eligible for Study:   18 Years and older   (Adult, Senior)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Male or female, age ≥18 years.
  • If the patient is a woman, she must be without reproductive potential (i.e., postmenopausal for ≥2 years or after hysterectomy).
  • AF at the time of enrollment (randomization) or documented within the last year by Holter, ECG, rhythm strip, pacemaker or other intracardiac recording, resulting in an indication for anticoagulation with warfarin, acenocumerol, phenprocoumon, or other Vitamin K antagonist in the opinion of the treating physician.
  • One or more of the following risk factor(s) for stroke:

    1. Age 75 years or older.
    2. Prior stroke, TIA or systemic (i.e., central nervous system) embolus at least 30 days remote from the time of screening.
    3. Symptomatic congestive heart failure within 3 months echocardiography, radionuclide study or contrast angiography.
    4. Hypertension requiring pharmacological treatment.
    5. Diabetes.
    6. Age of 55 years or older and previous coronary artery disease or known peripheral artery disease.

Exclusion Criteria:

  • Body weight less than 40 kg (88 lbs).
  • Need for either hemodialysis or peritoneal dialysis (or likely to require it within one year).
  • AF due to reversible causes (e.g., thyrotoxicosis, pericarditis, cardiac surgery, pulmonary embolism).
  • Mechanical prosthetic valve (bioprosthetic valve is allowed) or valvular disease likely to be operated on within one year.
  • History (including family history) or symptoms of a congenital or acquired bleeding disorder or vascular malformation; or a history of intracranial, retroperitoneal, or intraocular bleeding within the last 6 months; or is felt to be at high risk for bleeding for other reasons including from significant liver disease. This also includes gastrointestinal bleeding within 90 days before randomization or endoscopically verified ulcer disease within 30 days of screening.
  • Conditions other than AF that require chronic anticoagulation (e.g. prosthetic mechanical heart valve).
  • Persistent, uncontrolled hypertension (SBP >160 mm Hg on repeated measurements).
  • Active infective endocarditis.
  • Scheduled major surgery.
  • Planned pulmonary vein ablation or surgical procedure for cure of AF or flutter.
  • Recent ischemic stroke, systemic embolic event or acute coronary syndrome within 30 days.
  • Severe co-morbid condition with life expectancy of ≤1 year.
  • Previous known history of genetic coagulopathy (e.g., Factor V Leiden, Protein C Deficiency, Protein S Deficiency, Antiphospholipid Syndrome, etc.).
  • Evidence at Screening of:

    1. Platelet count <100,000/mm3.
    2. Serum alanine aminotransferase (ALT) or aspirate aminotransferase (AST) >2 times ULN.
    3. A history (including family history) of "Long QT Syndrome".
  • Aspirin >162 mg daily.
  • Use of verapamil (pending the availability of a drug interaction study with betrixaban).
  • Active alcohol or drug abuse, or psychosocial reasons that make study participation impractical.
  • Use of an investigational drug or device within the past 30 days.
  • Inability to comply with INR monitoring or other protocol-related activities.
  • Unable to give written informed consent.
  Contacts and Locations
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Please refer to this study by its identifier: NCT00742859

United States, California
Portola Investigational Site
Anaheim, California, United States
United States, Colorado
Portola Investigational Site
Colorado Springs, Colorado, United States
United States, Florida
Portola Investigational Site
Melbourne, Florida, United States
Portola Investigational Site
Miami, Florida, United States
Portola Investigational Site
Ormond Beach, Florida, United States
Portola Investigational Site
Pensacola, Florida, United States
Portola Investigational Site
Port Charlotte, Florida, United States
United States, Illinois
Portola Investigational Site
Aurora, Illinois, United States
United States, Maine
Portola Investigational Site
Auburn, Maine, United States, 04210
United States, Maryland
Portola Investigational Site
Columbia, Maryland, United States
Portola Investigational Site
Salisbury, Maryland, United States
Portola Investigational Site
Towson, Maryland, United States
United States, Mississippi
Portola Investigational Site
Tupelo, Mississippi, United States
United States, Missouri
Portola Investigational Site
Saint Louis, Missouri, United States
United States, New York
Portola Investigational Site
Poughkeepsie, New York, United States
United States, Oregon
Portola Investigational Site
Hillsboro, Oregon, United States
United States, Pennsylvania
Portola Investigational Site
Wynnewood, Pennsylvania, United States
United States, South Dakota
Portola Investigational Site
Rapid City, South Dakota, United States
United States, Virginia
Portola Investigational Site
Norfolk, Virginia, United States
Canada, Quebec
Portola Investigational Site
Longueuil, Quebec, Canada
Portola Investigational Site
Montreal, Quebec, Canada
Sponsors and Collaborators
Portola Pharmaceuticals
Study Chair: Stuart Connolly, MD, FRCP Population Health Research Institute, McMaster University
Study Director: Rafael Diaz, MD Instituto Cardiovascular de Rosario, Argentina
Study Director: Paul Dorian, MD University of Toronto, Canada
Study Director: Michael Ezekowitz, MD, PhD, Lankenau Institute for Medical Research and The Heart Center, United States
Study Director: Stefan H. Hohnloser, MD Johann Wolgang Goethe University, Frankfurt, Germany
  More Information

Responsible Party: Portola Pharmaceuticals Identifier: NCT00742859     History of Changes
Other Study ID Numbers: 08-015
Study First Received: August 26, 2008
Last Updated: July 12, 2017

Keywords provided by Portola Pharmaceuticals:
Atrial Fibrillation
Factor Xa inhibitor

Additional relevant MeSH terms:
Atrial Fibrillation
Arrhythmias, Cardiac
Heart Diseases
Cardiovascular Diseases
Pathologic Processes
Factor Xa Inhibitors
Serine Proteinase Inhibitors
Protease Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action processed this record on August 18, 2017