Biomarkers for new anticoagulants – vice and virtue Dagmar Kubitza, MD AGAH, München 2014 Page 1
Definition of Biomarkers?
….Surrogate markers are primary measures the effectiveness of investigational drugs….
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Biomarkers for new oral anticoagulants… …which biomarkers?
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Charles Esmon, Ann Rev Cell Biol 1993
Biomarkers for new anticoagulants -the „old fashioned way“?
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Mani et al, Thrombosis Journal 2013
Direct inhibitors of Factor Xa prolong PT
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Samama et al, Thrombosis Research 2011
Samama et al, Thrombosis Haemostasis 2010
Direct inhibitors of Factor Xa prolong PT
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Samama et al, Thrombosis Research 2011
Samama et al, Thrombosis Haemostasis 2010Douxfils et al, Thrombosis Haemostasis 2013
Direct inhibitors of Factor Xa prolong PT
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Samama et al, Thrombosis Research 2011
Samama et al, Thrombosis Haemostasis 2010Douxfils et al, Thrombosis Haemostasis 2013
Fonaparinux has no effect on PT
Some direct inhibitors of Factor Xa prolong PT
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Samama et al, Thrombosis Research 2011
Samama et al, Thrombosis Haemostasis 2010Douxfils et al, Thrombosis Haemostasis 2013
Fonaparinux has no effect on PT
Calculation of INR does not decrease the variablility of the results of the different thromboplastin reagents
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Samama et al, Thrombosis Research 2011
Background information about PT PT assays are designed to reliably measure the effect of Vitamin K
antagonists
Different reagents use different thromboplastins to start the clot formation ex vivo, e.g. rabbit brain, placenta, recombinant
Concentrations of phospholipids and ions vary between tests and evenbetween lots.
Components are added to ensure the optimal performance of tests, someassays even contain heparins.
ISI (international sensitivity index) should ensure comparability between tests, but they are optimized for Vitamin K antagonists.
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What influences the PT sensitivity of direct Factor Xa inhibitors?
PT sensitivity of Rivaroxaban varies depending on the composition of thethromboplastin reagent PT sensitivity increases with Decreasing concentrations of tissue factor Increasing concentratíons of phospholipids and NaCL Presence of phosphadidylethanolamine
PT sensitivity decreases with Increasing percentage of phosphadidylserine
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Smith & Morrissey, Blood 2007
Why? Hpothesis The faster that factor Xa is generated and assembled into the prothrombinase
complex, the less sensitive will the clotting time be on Rivaroxabanconcentration.
Perhaps this is because it allows factor Xa to generate thrombin before Rivaroxaban can inhibit it effectively during the very short duration of most clotting tests.
It remains unclear why Apixaban behaves different than Rivaroxaban and Edoxaban.
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Smith & Morrissey, Blood 2007
Is PT a useful biomarker?PT can be used to provide insights into the pharmacodynamic effects of anticoagulants if … comparisons are made for one compound comparisons are made from preclinical to clinical study results, provided that
the same assay is used comparisons are made between studies of one compound and a central lab
has been used
Comparisons of pharmacodynamic effects between different compounds cannotbe reliably done with PT
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Will a broader view on the coagulationsystem provide better insights?
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Endogenous thrombin potential (ETP)• Is the total amount of thrombin which is generated in plasma• It reflects the sum of the activity and concentration of pro-coagulant and
anti-coagulant substances
ETP-AUCtotal amount of thrombin that can be generated
PeakMaximal hight of the TG curve
Lag timeTime interval until thrombin generation starts
Time to peakTime interval until the peak of thrombin generationoccurrs
Influence of Dabigatran on Thrombin Generation
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Dabigatran mainly delayed the initiation phase with strong dose-dependent increase of lag time and time to peak and a slight dose-dependent decrease in peak hight and ETP
Douxfils et al, Thromb Haemost 2012
Influence of Rivaroxabanon Thrombin Generation
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a contolb 5nM ~ 2,2 µg/Lc 10nM ~ 4,4 µg/Ld 20nM ~ 8,7µg/Le 50nM ~21,7µg/Lf 80nM ~34,9µg/Lg100nM ~43,5µg/L
Gerotziafas et al, J Thromb Haemost 2007
Influence of Rivaroxaban and Edoxabanon Thrombin Generation
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a contolb 5nM ~ 2,2 µg/Lc 10nM ~ 4,4 µg/Ld 20nM ~ 8,7µg/Le 50nM ~21,7µg/Lf 80nM ~34,9µg/Lg100nM ~43,5µg/L
Gerotziafas et al, J Thromb Haemost 2007 Samama et al, Thrombosis Research 2012
Rivaroxaban and Edoxaban affect the initiation and amplificationphase of thrombin generation by affecting all parameters of TG
Influence of Apixaban and Fondaparinuxon Thrombin Generation
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Apixaban and Fondaprinux mainly act on the amplificationphase of TG by affecting the peak and the velocity rate index
Douxfils et al, Thrombosis Haemost 2013 Samama et al, Thrombosis Research 2012
Will a broader view on the coagulation systemprovide better insights? Thrombin Generation is a sensitive marker for anticoagulant effects
independent of the mode of action. Compounds with a different mode of action have different effects on TG. Compounds with the same mode of action have different effects on TG.
☻ Comparisons of pharmacodynamic effects between different compoundscannot be reliably done.
☻It remains unclear what the clinical relevance of the differences in influence of individual parameters of TG is.
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Dabigatran can be measured with HTIHemoclot Thrombin Inhibitor
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Hemoclot Thrombin Inhibitor shows a concentation dependent prolongation of clottingtime with linear relation and a good reproducibility
Douxfils et al, Thromb Haemost 2012
Anti-Xa assays with specific calibrators and controls forRivaroxabanshow linear concentration dependent decrease in OD
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Hyphen Biomed, France
Samama et al, J Thromb Thrombolysis, 2012
Samama et al, Thromb Heamost, 2010
Anti-Xa assays with specific calibrators and controlsfor Rivaroxaban and Edoxaban show linear concentration dependent decrease in OD
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Samama et al, Thrombosis Research 2012
Hyphen Biomed, France
Samama et al, J Thromb Thrombolysis, 2012
Samama et al, Thromb Heamost, 2010
Anti-Xa assays with specific calibrators and controlsfor Apixaban
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Douxfils et al, Thrombosis Haemost 2013
Most sensitive reagents show an exponential correlation but the dynamicrange of quantification is lower.
Can the DOAKs be reliably measuredin clinical practice?
Chromogenic assays with drug specific calibrators and controls can be usedto reliably measure direct oral anticoagulants
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Biomarkers for new anticoagulants –vice and virtue
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Mani et al, Thrombosis Journal 2013
Yes, the pharmacodynamic effects of the DOACs can be determined by biomarkersBUT …
Biomarkers for new anticoagulants –vice and virtue
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Mani et al, Thrombosis Journal 2013
Yes, the pharmacodynamic effects of the DOACs can be determined by biomarkersBUT
Many influencing factors have to be considered in interpreting the results.