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A Study in Patients With Acute Major Bleeding to Evaluate the Ability of Andexanet Alfa to Reverse the Anticoagulation Effect of Direct and Indirect Oral Anticoagulants

This study is currently recruiting participants.
Verified April 2017 by Portola Pharmaceuticals
ClinicalTrials.gov Identifier:
First Posted: December 31, 2014
Last Update Posted: April 5, 2017
The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Know the risks and potential benefits of clinical studies and talk to your health care provider before participating. Read our disclaimer for details.
Population Health Research Institute
Information provided by (Responsible Party):
Portola Pharmaceuticals
The purpose of this study is to evaluate the hemostatic efficacy of andexanet alfa in patients receiving a factor Xa inhibitor who are experiencing an acute major bleed. The safety of andexanet will also be studied.

Condition Intervention Phase
Bleeding Biological: Andexanet Phase 3

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Primary Purpose: Other
Official Title: Prospective, Open-Label Study of Andexanet Alfa in Patients Receiving a Factor Xa Inhibitor Who Have Acute Major Bleeding (ANNEXA-4)

Resource links provided by NLM:

Further study details as provided by Portola Pharmaceuticals:

Primary Outcome Measures:
  • Proportion of patients with excellent or good hemostasis [ Time Frame: Stopping major bleed at 12 hours from the start of andexanet bolus ]

Estimated Enrollment: 350
Study Start Date: January 2015
Estimated Primary Completion Date: November 2022 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: Single Arm Biological: Andexanet


Information from the National Library of Medicine

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


  1. Acute major bleeding episode requiring urgent reversal of anticoagulation; defined by at least one of the following:

    • Acute bleeding that is potentially life-threatening, OR
    • Acute bleeding associated with a fall in hemoglobin level by ≥2 g/dL, OR
    • Acute bleeding associated with a hemoglobin level of ≤8 g/dL if no baseline hemoglobin is available, OR
    • Acute bleeding in a critical area or organ such as intraspinal, pericardial, or intracranial.
  2. If bleeding is intracranial or intraspinal, the patient must have undergone a head CT or MRI scan demonstrating the bleeding.
  3. Patient received or is believed to have received one of the following within 18 hours prior to andexanet administration: apixaban, rivaroxaban, edoxaban or enoxaparin.
  4. For patients with intracranial bleeding, there must be a reasonable expectation that andexanet treatment will commence within 2 hours of the baseline imaging evaluation.


  1. The patient is scheduled to undergo surgery in less than 12 hours, with the exception of minimally invasive surgery/procedures.
  2. A patient with an intracerebral hemorrhage has any of the following:

    • Glasgow coma score < 7, OR
    • Intracerebral hematoma > 60 cc as assessed by CT or MRI
  3. Patients with visible, musculoskeletal or intra-articular bleeding as their qualifying bleed.
  4. Expected survival of less than 1 month
  5. Recent history (within 2 weeks) of a diagnosed thrombotic event (TE) as follows: venous thromboembolism, myocardial infarction, disseminated intravascular coagulation (DIC), cerebral vascular accident, transient ischemic attack, unstable angina pectoris hospitalization or severe peripheral vascular disease within 2 weeks prior to screening.
  6. Severe sepsis or septic shock at the time of Screening.
  7. Pregnant or a lactating female.
  8. Patient has received any of the following drugs or blood products within 7 days of Screening:

    • Vitamin K antagonist (VKA)
    • Dabigatran
    • Prothrombin Complex Concentrate products (PCC) or recombinant factor VIIa (rfVIIa)
    • Whole blood, plasma fractions
  9. Treated with an investigational drug <30 days prior to Screening
  10. Planned administration of PCC, fresh frozen plasma (FFP) or rfVIIa from Screening until within 12 hours after the end of the andexanet infusion.
  Contacts and Locations
Information from the National Library of Medicine

To learn more about this study, you or your doctor may contact the study research staff using the contact information provided by the sponsor.

Please refer to this study by its ClinicalTrials.gov identifier (NCT number): NCT02329327

Contact: Patrick Yue, M.D. 650.246.7000 fXaantidote@portola.com

  Show 44 Study Locations
Sponsors and Collaborators
Portola Pharmaceuticals
Population Health Research Institute
  More Information

Publications automatically indexed to this study by ClinicalTrials.gov Identifier (NCT Number):
Responsible Party: Portola Pharmaceuticals
ClinicalTrials.gov Identifier: NCT02329327     History of Changes
Other Study ID Numbers: 14-505
First Submitted: December 18, 2014
First Posted: December 31, 2014
Last Update Posted: April 5, 2017
Last Verified: April 2017

Keywords provided by Portola Pharmaceuticals:
Factor Xa Inhibitors

Additional relevant MeSH terms:
Pathologic Processes
Factor Xa Inhibitors
Serine Proteinase Inhibitors
Protease Inhibitors
Enzyme Inhibitors
Molecular Mechanisms of Pharmacological Action