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The Proteins of the Contact Activation System (CONTACT)

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. Read our disclaimer for details. Identifier: NCT02785718
Recruitment Status : Unknown
Verified May 2016 by Hospices Civils de Lyon.
Recruitment status was:  Recruiting
First Posted : May 30, 2016
Last Update Posted : June 1, 2016
Information provided by (Responsible Party):
Hospices Civils de Lyon

Brief Summary:

Cardiovascular diseases are important causes of morbidity and mortality in the industrialized world. Abnormalities in the coagulation system, causing a hypercoagulable state, are a known risk factor for arterial and venous thrombosis. The contact activation system is part of the coagulation system and consists of four proteins: coagulation factor XII (FXII), FXI, prekallikrein and high molecular weight kininogen (HMWK). Clinical studies indicate an important role for the contact activation system on the risk of arterial thrombosis. Furthermore, there is substantial evidence from mouse studies that FXII and FXI participate in the formation and stability of thrombi. In vitro studies show that collagen, present in the vascular wall, is able to activate FXII and hereby stimulate thrombin formation and potentiate the formation of platelet-fibrin thrombi and FXIIa is able to change the structure of fibrin clots by binding to fibrin(ogen) and by generation of additional thrombin. However, the contact system also participates in the process of fibrinolysis, which degrades thrombi.

The investigators would like to investigate the contribution of the contact activation system to the formation of thrombi. The formation of a thrombus within the vascular bed is the main cause for occlusion of an artery or vein, which can lead to an infarct such as a heart attack. Due to the other functions of the contact system it is important to fully understand how the contact system contributes to thrombus formation, before it can be used as a target in the treatment of arterial thrombosis. The aim of this study is to determine the contribution of the proteins of the contact system, mainly FXII and FXI, in the platelet mediated formation and degradation of thrombi. This will be studied in flow models (perfusion-flow model and Chandler loop), in a static model (ROTEM®) and using thrombin generation assay.

Condition or disease Intervention/treatment Phase
Factor XI Deficiency Factor XII Deficiency Other: Global Haemostasis assays Not Applicable

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Study Type : Interventional  (Clinical Trial)
Estimated Enrollment : 18 participants
Allocation: N/A
Intervention Model: Single Group Assignment
Masking: None (Open Label)
Official Title: The Influence of the Proteins of the Contact Activation System on Thrombus Formation in Human Blood
Study Start Date : June 2015
Estimated Primary Completion Date : September 2016
Estimated Study Completion Date : September 2016

Arm Intervention/treatment
Experimental: Patients with FXI or FXII deficiency
12 patients with FXI deficiency and 6 patients with FXII deficiency
Other: Global Haemostasis assays

Primary Outcome Measures :
  1. fibrinolytic degradation rate of the formed clots by ROTEM analysis [ Time Frame: 1 day (cross sectional) ]

Secondary Outcome Measures :
  1. the ex-vivo formation of platelet-mediated thrombi on collagen in a perfusion flow mode [ Time Frame: 1 day (cross sectional) ]
  2. biochemical composition of the thrombi formed in the Chandler loop [ Time Frame: 1 day (cross sectional) ]
  3. endogenous thrombin potential (ETP) of the platelet rich plasma of these patients [ Time Frame: 1 day (cross sectional) ]

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Ages Eligible for Study:   18 Years to 65 Years   (Adult, Older Adult)
Sexes Eligible for Study:   All
Accepts Healthy Volunteers:   No

Inclusion Criteria:

  • Deficiency in coagulation factor XII and factor XI (factor level<5%)
  • Subjects of both gender
  • Age ≥18 and ≤ 65
  • Written informed consent from the subject
  • Subject with a social security plan or beneficiary of such a plan.

Exclusion Criteria:

  • Age below 18
  • Age above 65
  • Other known abnormalities of the coagulation system
  • Thrombocytopenia
  • Known platelet disorders
  • Personal history of severe liver diseases
  • Symptoms of active disease (e.g. cancer)
  • The use of antiplatelet drugs
  • The use of drugs that interfere with coagulation
  • Ongoing diagnosed pregnancy upper 3 months
  • Adult patients protected by law
  • Concomitant participation to a biomedical research

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 identifier (NCT number): NCT02785718

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Contact: Yesim DARGAUD, MD PHD (0)4 72 11 88 25 ext +33

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Unité d'Hémostase Clinique Hôpital Louis Pradel Recruiting
Bron, France, 69500
Contact: Yesim Dargaud, MD, PhD    (0)4 72 11 88 25 ext +33   
Principal Investigator: Yesim Dargaud, MD, PhD         
Sponsors and Collaborators
Hospices Civils de Lyon
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Responsible Party: Hospices Civils de Lyon Identifier: NCT02785718    
Other Study ID Numbers: 2012.785
First Posted: May 30, 2016    Key Record Dates
Last Update Posted: June 1, 2016
Last Verified: May 2016
Keywords provided by Hospices Civils de Lyon:
Contact system
Factor XI deficiency
Factor XII deficiency
Global haemostasis assays
Additional relevant MeSH terms:
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Factor XI Deficiency
Factor XII Deficiency
Blood Coagulation Disorders, Inherited
Blood Coagulation Disorders
Hematologic Diseases
Coagulation Protein Disorders
Hemorrhagic Disorders
Genetic Diseases, Inborn