Haemostasis and NovoSeven ®

1. Haemostasis and NovoSeven® The updated cell-based model of haemostasis and NovoSeven® (rFVIIa) mode of action

2. Chapter ► 1. The haemostatic system 2. Primary haemostasis 3. Secondary haemostasis 4. NovoSeven® mode of action

3. The haemostatic system – The three phases Primary haemostasis: • Vasoconstriction (immediate) • Platelet adhesion (within seconds) • Platelet aggregation and contraction (within minutes) Secondary haemostasis: • Activation of coagulation factors (within seconds) • Formation of fibrin (within minutes) Fibrinolysis: • Activation of fibrinolysis (within minutes) • Lysis of the plug (within hours)

4. The haemostatic system – Blood vessel and endothelium • Haemostasis requires and involves various physiological components: • The blood vessel wall • Endothelial cells • Subendothelial tissue • Smooth muscle cells • The components of blood • Platelets (thrombocytes) • Coagulation (clotting) factors • Fibrinolytic/ anticoagulant proteins

5. Chapter 1. The haemostatic system ► 2. Primary haemostasis 3. Secondary haemostasis 4. NovoSeven® mode of action

6. Primary haemostasis –Vasoconstriction • The first response to endothelial injury is the constriction of the damaged vessel which reduces the blood flow at the site of injury1

7. Primary haemostasis –Formation of a platelet plug • The exposure of subendothelial components such as collagen promotes platelet adhesion1,2 • The adherence of platelets to the sub-endothelium leads to platelet activation and the formation of platelet aggregates (platelet plug)2

8. Chapter 1. The haemostatic system 2. Primary haemostasis ► 3. Secondary haemostasis 4. NovoSeven® mode of action

9. Secondary haemostasis • Secondary haemostasis involves a series of interactions between coagulation factors which occur on the surface of tissue-factor-bearing cells and activated platelets1,2 • This results in the generation of a thrombin burst and the formation of a haemostatic plug at the site of vascular injury1,2 • Based on the “cell-based model”, coagulation occurs in three overlapping phases – initiation, amplification and propagation1,2

10. Secondary haemostasis –Initiation phase • Upon vessel wall injury, tissue factor (TF) is exposed to circulating endogenous factor VII/VIIa – leading to the TF/VIIa complex which initiates coagulation1,2 • At the surface of TF-bearing cells the TF/VIIa complex activates:1,2 • Factor IX to IXa  • Factor X to Xa  • Factor Xa binds to factor Va on the cell surface1,2 Adapted from Hoffman M et al., 2001.1

11. Secondary haemostasis – Amplification phase • The factor Xa/Va complex activates small amounts of prothrombin to thrombin at the surface of subendothelial cells1,2 • This limited amount of thrombin activates factors V, VIII and platelets3 • The activated plateletbinds factors Va, VIIIaand IXa1 Adapted from Hoffman M et al., 2001.1

12. Secondary haemostasis – Propagation phase • Thrombin-activated platelets change shape and expose negatively charged phospholipids to which the factor VIIIa/IXa complex binds • This results in factor X activation on the surface of activated platelets1,2 • The factor Xa/Va complex activates large amounts of prothrombin resulting in a “thrombin burst” which: • Converts fibrinogen to fibrin1,2 • Activates fibrin-stabilising factor XIII2 • The amount and rate of thrombin generation determines the strength of the haemostatic plug3 Adapted from Hoffman M et al., 2001.1

13. Secondary haemostasis – Thrombin burst The thrombin burst is particularly important because it: • Converts fibrinogen into fibrin monomers, which polymerise and form the mesh-work basis of the haemostatic plug1,2 • Activates more platelets and other factors, thereby further amplifying the system1,2 • Activates thrombin-activatable fibrinolysis inhibitor (TAFI) which protects the plug from fibrinolysis3 • Activates factor XIII, which helps stabilising the haemostatic plug4

14. Overview of secondary haemostasis1-3 • Upon vessel wall injury, tissue factor (TF) is exposedto circulating endogenousfactor VII/VIIa – leading tothe TF/VIIa complex, whichinitiates coagulation  • A limited amount ofthrombin activates factors V, VIII and platelets  • Activation of factor X leadsto the formation of the prothrombinase complex Xa/Va which subsequently generates large amounts of thrombin  • This “thrombin burst” induces the generation of a haemostatic plug thatprevents further blood loss  Adapted from Hoffman M et al., 2001.1

15. Chapter 1. The haemostatic system 2. Primary haemostasis 3. Secondary haemostasis ► 4. NovoSeven® mode of action

16. NovoSeven® (rFVIIa) mode of action • At pharmacological doses NovoSeven® (rFVIIa) directly activates factor X on the surfaces of activated platelets1-3 • Once activated factor Xa in combination with factor Va generates large amounts of thrombin4 • This “thrombin burst” leads to the formation of a stable haemostatic plug at the site of vascular injury1

17. NovoSeven® (rFVIIa) controls bleeding at the site of vascular injury only1 • rFVIIa works locally at the site of vascular injury, where tissue factor (TF) is exposed and activated platelets are found1 • Binding of factor VIIa or rFVIIa to TF initiates the coagulation generating small amounts of thrombin2 • At pharmacological doses rFVIIa directly activates factor X on the surface of activated platelets resulting in a “thrombin burst”3,4 • The thrombin burst leads to the formation of a stable haemostatic plug which controls the bleeding3 Adapted from Hoffman M et al., 2001.1