Platelet function testing and clinical events: review of the evidence and are they prime for incorporation in clinical

1. Platelet function testing and clinical events: review of the evidence and are they prime for incorporation in clinical practice? Mohan Sathyamoorthy, M.D., F.A.C.C. Vice-Chief, Cardiovascular Division Baylor All Saints Medical Center, Fort Worth, TX Adjunct Assistant Clinical Professor of Medicine Vanderbilt Medical Center, Nashville, TN Cardiologist, HeartPlace, Fort Worth, TX

2. Learning Objectives Understand the key clinical data related to platelet function testing in clinical cardiovascular medicine Understand the key controversies related to these data Can one incorporate this data into your day to day clinical practice

3. Disclosures Speakers Bureau for: Lantheus Medical Imaging Gilead Biosciences Consultant for: None Active Research Grants: None

4. The Clinical Effectiveness of an Antiplatelet Agent�. A Platelet�s Response to a Drug vs. A Drug�s Bioavailability to a Platelet

5. What Key Questions Would You Ask about Platelet Function Testing?

6. ACS and �Coronary Injury� is a �Platelet-Centric Disease�

7. What Affects a Platelet�s Response to a Drug Platelet Biology Surface Receptor Biology P2Y12 TP (Thromboplastin) VW (VonWillenbrand. i.e. 2b3a) PAR (Protease Activated Receptors) Granule Biology Levels of Circulating Receptor Agonists

8. Central Role of Platelets and Interaction With Coagulation in the Genesis of Thrombosis

9. What Affects A Drug�s �Bio�Availability to A Platelet? Absorption kinetics Gut Pharmacokinetics and dynamics Initial and steady state Concomitant Medications Drug-drug interactions Metabolism, i.e. Pharmacogenetics Liver Cytochromes and SNPs

10. Clopidogrel Metabolism and Effect

11. So How Do These Factors Relate to a Clinical Endpoint? Both of these phenomenon ultimately DETERMINE�.. VARIABILITY OF RESPONSE TO THERAPY i.e. hyporesponsiveness or �resistance�

13. Baylor All Saints CV Conference 2010: Advances in CV Therapy, M. Sathyamoorthy, MD, FACC A notable observation during the development of prasugrel was this cross over study in 66 healthy volunteers. Plotted on the left is the IPA response to 300 mg of clopidogrel�note the wide interpatient variablilty and a considerable proportion of subjects , shown in blue, who were hyporesponders. When given 60 mg of prasugrel these same individuals had much less interpatient variability, a higher mean IPA, and all of the hyporesponders to clopidogrel had a significant response to prasugrel. A notable observation during the development of prasugrel was this cross over study in 66 healthy volunteers. Plotted on the left is the IPA response to 300 mg of clopidogrel�note the wide interpatient variablilty and a considerable proportion of subjects , shown in blue, who were hyporesponders. When given 60 mg of prasugrel these same individuals had much less interpatient variability, a higher mean IPA, and all of the hyporesponders to clopidogrel had a significant response to prasugrel.

14. Baylor All Saints CV Conference 2010: Advances in CV Therapy, M. Sathyamoorthy, MD, FACC

15. Baylor All Saints CV Conference 2010: Advances in CV Therapy, M. Sathyamoorthy, MD, FACC Risks of any cardiovascular event in aspirin resistant and aspirin sensitive patients treated with aspirin alone, and aspirin and clopidogrel (with or without an inhibitor of platelet glycoprotein IIb/IIIa) Risks of any cardiovascular event in aspirin resistant and aspirin sensitive patients treated with aspirin alone, and aspirin and clopidogrel (with or without an inhibitor of platelet glycoprotein IIb/IIIa)

17. So how do we assess �Responsiveness� in 2011 We test PLATELET FUNCTION We should now consider PHARMACOGENETIC TESTING i.e. liver cytochrome genotypes

19. Baseline Platelet Reactivity* Determines Outcomes Following Coronary Stenting

20. Studies Linking High Ex-Vivo Platelet Reactivity to ADP and Ischemic Events

21. Prognostic significance of high on-clopidogrel platelet reactivity after percutaneous coronary intervention: systematic review and meta-analysis. METHODS Systematic review and meta-analysis on the clinical relevance of HPR , observation studies 2003-2010 Outcome measures : cardiovascular (CV) death, definite/probable stent thrombosis (ST), nonfatal myocardial infarction (MI), and a composite end point of reported ischemic events. RESULTS Twenty studies , 9,187 patients High on-clopidogrel platelet reactivity MI: 3.00 [2.26-3.99, STEMI: 4.14 [2.74-6.25] Composite: 4.95 [3.34-7.34] P < .00001 for all cases CONCLUSIONS: According to the meta-analysis, patients with HPR had a 3.4-fold higher risk for CV death compared with patients with normal ADP reactivity (odds ratio 3.35, 95% CI 2.39-4.70, P < .00001). High on-clopidogrel platelet reactivity, measured by an ADP-specific platelet function assay, is a strong predictor of CV death, MI, and ST in patients after percutaneous coronary intervention. ISSUES Methodology Definition of HPR between studies Meta-analysis/Review

23. VerifyNow Point-of-Care Platelet Function Assay* Correlates with Clinical Outcomes Post-DES Deployment High post-treatment platelet reactivity measured with a point-of-care platelet function assay is associated with post-discharge events after PCI with DES, including stent thrombosis. Investigation of alternative clopidogrel dosing regimens to reduce ischaemic events in high-risk patients identified by this assay is warranted. (Price et al. Eur Heart J. 2008;29:992). Aims: The aim of this study was to determine whether platelet reactivity on clopidogrel therapy, as measured by a point-of-care platelet function assay, is associated with thrombotic events after percutaneous coronary intervention (PCI) with drug-eluting stents (DESs). Methods and results: Platelet reactivity on clopidogrel (post-treatment reactivity) was measured with the VerifyNow P2Y12 assay (Accumetrics Inc., San Diego, CA, USA) in 380 patients undergoing PCI with sirolimus-eluting stents. Receiver-operating characteristic curve analysis was used to derive the optimal cut-off value for post-treatment reactivity in predicting 6 month out-of-hospital cardiovascular (CV) death, non-fatal MI, or stent thrombosis. The mean post-treatment reactivity was 184 � 85 PRU (P2Y12 reaction units). The optimal cut-off for the combined endpoint was a post-treatment reactivity 235 PRU [area under the curve 0.711 (95% confidence interval 0.529�0.893), P = 0.03], which was similar to the threshold of the upper tertile (231 PRU). Patients with post-treatment reactivity greater than the cut-off value had significantly higher rates of CV death (2.8 vs. 0%, P = 0.04), stent thrombosis (4.6 vs. 0%, P = 0.004), and the combined endpoint (6.5 vs. 1.0%, P = 0.008). Conclusion: High post-treatment platelet reactivity measured with a point-of-care platelet function assay is associated with post-discharge events after PCI with DES, including stent thrombosis. Investigation of alternative clopidogrel dosing regimens to reduce ischaemic events in high-risk patients identified by this assay is warranted. Key Words: Platelets � Thienopyridine � Stent � Clopidogrel � Thrombosis High post-treatment platelet reactivity measured with a point-of-care platelet function assay is associated with post-discharge events after PCI with DES, including stent thrombosis. Investigation of alternative clopidogrel dosing regimens to reduce ischaemic events in high-risk patients identified by this assay is warranted. (Price et al. Eur Heart J. 2008;29:992). Aims: The aim of this study was to determine whether platelet reactivity on clopidogrel therapy, as measured by a point-of-care platelet function assay, is associated with thrombotic events after percutaneous coronary intervention (PCI) with drug-eluting stents (DESs). Methods and results: Platelet reactivity on clopidogrel (post-treatment reactivity) was measured with the VerifyNow P2Y12 assay (Accumetrics Inc., San Diego, CA, USA) in 380 patients undergoing PCI with sirolimus-eluting stents. Receiver-operating characteristic curve analysis was used to derive the optimal cut-off value for post-treatment reactivity in predicting 6 month out-of-hospital cardiovascular (CV) death, non-fatal MI, or stent thrombosis. The mean post-treatment reactivity was 184 � 85 PRU (P2Y12 reaction units). The optimal cut-off for the combined endpoint was a post-treatment reactivity 235 PRU [area under the curve 0.711 (95% confidence interval 0.529�0.893), P = 0.03], which was similar to the threshold of the upper tertile (231 PRU). Patients with post-treatment reactivity greater than the cut-off value had significantly higher rates of CV death (2.8 vs. 0%, P = 0.04), stent thrombosis (4.6 vs. 0%, P = 0.004), and the combined endpoint (6.5 vs. 1.0%, P = 0.008). Conclusion: High post-treatment platelet reactivity measured with a point-of-care platelet function assay is associated with post-discharge events after PCI with DES, including stent thrombosis. Investigation of alternative clopidogrel dosing regimens to reduce ischaemic events in high-risk patients identified by this assay is warranted. Key Words: Platelets � Thienopyridine � Stent � Clopidogrel � Thrombosis

24. DES Thrombosis and Residual Platelet Reactivity

35. This plot illustrates the PRUs 12 to 24 hours after PCI in the patients who had events, stratified by group. The post-PCI PRUs in the patients without high reactivity were clustered within the upper range for that group, the majority near the threshold of 230 PRU. This observation must be considered exploratory and hypothesis-generating. This plot illustrates the PRUs 12 to 24 hours after PCI in the patients who had events, stratified by group. The post-PCI PRUs in the patients without high reactivity were clustered within the upper range for that group, the majority near the threshold of 230 PRU. This observation must be considered exploratory and hypothesis-generating.

36. In summary, In summary,

39. NeumannNeumann

40. ASCET (PFA-100) AHA SS 11/2010 Primary Objective: Clinical outcome (composite USA+MI+CVA+Death) over 2 years in patients with �stable� symptomatic CAD on ASA therapy as related to initial aspirin response via PFA-100 Secondary Objective: Investigate the difference in composite event rate between patients treated with ASA vs Clopidrogel

41. ASCET (PFA-100) AHA SS 11/2010 Results Composite Endpoint when ASA no RPR (n=373) 10.5% vs ASA high RPR (n=130) 13.1% p=0.44 Composite Endpoint with RPR on ASA when treated with ASA 13.1% (n=130) or Clopidrogel 7.8% (n=129) p=0.16 26% of patients had RPR while on ASA by PFA-100 Conclusions No difference in composite endpoints RPR by PFA-100 did NOT predict clinical outcome Trend seems to indicate fewer endpoints using clopidrogel in patients with high RPR vs. ASA

43. Platelet reactivity after clopidrogrel treatment assessed with point-of-care analysis (MEA) and early drug-eluting stent thrombosis. HYPOTHESIS: Does platelet reactivity to clopidogrel assessed with multiple electrode platelet aggregometry (MEA) correlate with the risk of early drug-eluting stent thrombosis? METHODS: 2/07-2/08, 1608 patients Before PCI, all patients received 600 mg clopidogrel. The ADP-induced platelet aggregation was assessed in whole blood with a MEA. The primary end point was definite ST at 30 days. RESULTS: Compared with normal responders (n = 1,285), low responders (MEA upper qunitile, n = 323) had a significantly higher risk of: definite ST within 30 days (2.2% vs. 0.2%; odds ratio [OR]: 9.4; 95% confidence interval [CI]: 3.1 to 28.4; p < 0.0001) Mortality rates were 1.2% in low versus 0.4% in normal responders (OR: 3.2; 95% CI: 0.9 to 11.1; p = 0.07). Composite of death or ST was higher in low versus normal responders (3.1% vs. 0.6%; OR: 5.1; 95% CI: 2.2 to 11.6; p < 0.001).

44. Clopidogrel response status assessed with Multi-plate point-of-care analysis (MEA) and the incidence and timing of stent thrombosis over six months following coronary stenting. 6 Month followup data from Sibbing D et al, J Am Coll Cardiol. 2009 Mar 10;53(10):849-56. Cumulative incidence of definite ST within six months was significantly higher in low responders [2.5% vs. 0.4%; OR 6.5; 95% CI, 2.4-17.0; P<0.001]. The combined incidence of definite or probable ST was higher as well in low vs. normal responders [4.1% vs. 0.7%; OR 5.8; 95% CI, 2.8-12.3; P<0.0001]. A significant inverse correlation of MEA values and the timing of definite or probable ST (in days) was observed (Spearman coefficient = -0.45; P=0.04) CONCLUSION MEA measurements are highly predictive for the occurrence of ST during the first six months following coronary stenting. In the majority of clopidogrel low responders suffering ST, the ischemic event occurs early in the course after the procedure.

45. STUDY DESIGN

46. VASP Guided PCI

47. VASP and LTA: limitations Not-user friendly Time consuming Require experienced lab personnel Require expensive equipment Not universally available Overall,�.expensive

48. Mechanism of Clopidogrel Response Variability

49. Residual Platelet Aggregation Stratified by CYP2C19*2 Genotype

50. Clopidogrel Non-ResponsivenessCorrelation With CYP3A4 Enzyme Activity

52. Strategies to Improve/Overcome Clopidogrel Response Increase clopidogrel dose (What data do we believe?? GRAVITAS implies NO!) Prasugrel! New pharmacologic agents coming�.(ticagrelor, AZD6140, cangrelor) Is there a role for CYP inducers (St. John�s Wort, etc.) to enhance conversion? Triple antiplatelet regimens (cilostazol, dipirydamole)?

53. Learning Objectives Understand the key clinical data related to platelet function testing in guiding clinical decision making OPTIMUS GRAVITAS TRIGGER-PCI ASCET MEA Studies (JACC 2010, TH 2010) Mega et al, NJEM 2009

54. Learning Objectives Understand the key controversies related to these data� Is there really a standard definition of �responsiveness or resistance� Cut points matter, and we fundamentally DO NOT have a consensus What is the best test? Do we combine platelet function testing and Genotype testing in a POC method?

55. Learning Objectives Can one incorporate this data into your day to day clinical practice and do we have GUIDELINES supporting this? ISTH Consensus Statement: Do not test ASA or clopidogrel resistance outside of clinical trials or to change therapy based on such testing. Why? NO clinically meaningful, standardized definition of resistance based on data linking therapy-dependent laboratory tests to clinical outcomes . Correct treatment of patients whose platelets are hyporesponsive to antiplatelet agents is unknown.

56. Guidelines Continued AHA/ACC/ASCI: Daily ASA therapy after PCI for patients without ASA ��resistance,�� but no definition of resistance is offered. Class IIb, level C recommendation For clopidogrel, the guidelines state that �� . . .in patients in whom stent thrombosis may be catastrophic or lethal. . . Platelet aggregation studies may be considered and the dose of clopidogrel increased to 150 mg per day if less than 50% inhibition of platelet aggregation is demonstrated.�� What about GRAVITAS??? Method to assess platelet inhibition is not described.