1. Clopidogrel Pharmacogenetics: Ready for Prime-Time?
Stephen D Wiviott MD
Brigham and Women’s Hospital
TIMI Study Group
Harvard Medical School

2. Conflicts of Interest
Research Funding: Eli Lilly, Daiichi Sankyo, Merck/Schering Plough
Consulting, CME Speaking Honoraria: Eli Lilly, Daiichi Sankyo, sanofi-aventis, Schering Plough, Astra Zeneca, ARENA, Novartis, Bayer

3. Why do we give patients clopidogrel?
It’s NOT MAGIC, It’s drug effect:
Clopidogrel is metabolized to an active metabolite
The active metabolite binds to platelets and inhibits platelet activation/aggregation
Inhibition of platelet aggregation results in less platelet mediated thrombosis
Less platelet mediated thrombosis results in fewer clinical ischemic events in patients

4. Why Genetics Matters When Choosing Antiplatelet Therapy
Reduced Function Alleles of CYP 2C19
Associated with less efficient metabolism of clopidogrel
Associated with less platelet inhibition on clopidogrel
Associated with worse ischemic outcomes in ACS with PCI
Less effect in conditions with less clopidogrel effect (AF, Chronic CAD)
Not associated with worse outcomes with more potent agents

5. Clopidogrel → Active MetaboliteN S O Cl
CH3 C
Compliance
Pro-drug
Clopidogrel
Environmental
Drug-Drug
Genetics
Hydrolysis
(Esterases)
85% Inactive Metabolites
hCE1
Active Metabolite
HOOC
* HS N O Cl
OCH3
Oxidation
(Cytochrome P450)
CYPs: 1A2 2B6 2C19
CYPs: 3A 2B6 2C9 2C19 S
CH3 C
Kurihara A. et al. Drug Metab. Rev. 37(S2): 99 (2005)
Tang M. et al. JPET 319: (2006) 5 5

6. GWAS of Platelet Aggregation in Response to Clopidogrel14 1 2 3 4 5 6 7 8 9 10 11 12 13 15 16 18 20 22
CYP2C18-CYP2C19-CYP2C9-CYP2C8
Cluster
Chromosome
-log10 (P Value)
GWAS = genome-wide association study.
Shuldiner A, et al. JAMA. 2009;302: 6

7. GRAVITAS: Pharmacodynamic Outcomes
Effect of study drug in patients with high OTR
Events in Patients Treated with 75 mg
However, it appeared that high-dose clopidogrel provided a variable and modest reduction in on-treatment reactivity compared with standard dose therapy.
High-dose provided variable and modest reduction in on-treatment reactivity (OTR)
Post-hoc: “responders” with events had OTR clustered just below 230 PRU
Price MJ, AHA 2010

8. Predicted CYP2C19 Metabolic Phenotype Is A Major, Independent Predictor of High OTR Post-PCI
Ultra, Ultra-rapid; Ext, Extensive; Int, Intermediate
Adjusted for BMI, gender, age, current smoking, CrCl<60 ml/min, DM, CHF, HTN, hyperlipidemia

9. Results: Influence of PON1, CYP2C19, and ABCB1 on the Primary Endpoint
P < for statistical significance
On-Treatment Reactivity at Screening (12-24 hrs post-PCI) N=1013
SNP R2
PON1 Q192R
0.2%
P = 0.42
CYP2C19*2
6.5%
P = 2.2 x 10-15
CYP2C19*17
0.5%
P = 0.08
ABCB CT
0.1%
P = 0.61
Change in On-Treatment Reactivity at 30 days N=714
SNP R2
PON1 Q192R 0%
P = 0.71
CYP2C19*2
5.1%
P = 1.4 x 10-5
CYP2C19*17
1.2%
P = 0.02
ABCB CT
P = 0.40
Co-dominant model, adjusted for tx and characteristics associated with OTR.

10. Effects of CYP2C19*2 and *17 Combined
ACC 2010 Montalescot FINAL_030810
Effects of CYP2C19*2 and *17 Combined
N=445 patients; 24 hours post 600-mg clopidogrel loading dose
Slow
Normal
Fast
Frequency 3%
3.5%
PRI=platelet reactivity index; VASP=vasodilator-stimulated phosphoprotein. Frére C, et al. J Thromb Haemost. 2009;7(8): 10 10

11. CYP2C19*2 and Clinical Outcomes With Clopidogrel
ACC 2010 Montalescot FINAL_030810
ACC 2010 Montalescot CE Approved_030210
CYP2C19*2 and Clinical Outcomes With Clopidogrel
Mega/p 359/Figure 3A
Collet/p 314/Figure 3A
Simon/p 372/Figure 2B 3
Collet JP, Hulot JS, Pena A, et al. Cytochrome P450 2C19 polymorphism in young patients treated with clopidogrel after myocardial infarction: a cohort study. Lancet. 2009;373(9660):
Simon T, Verstuyft C, Mary-Krause M, et al; French Registry of Acute ST-Elevation and Non-ST-Elevation Myocardial Infarction (FAST-MI) Investigators. Genetic determinants of response to clopidogrel and cardiovascular events. N Engl J Med. 2009;360(4):
*Death, nonfatal myocardial infarction, or urgent revascularization. †Composite of death from cardiovascular causes, myocardial infarction, or stroke. 1Reprinted with permission from Collet JP, et al. 2009;373(9660): Reprinted with permission from Mega JL, et al. N Engl J Med. 2009;360(4): Reprinted with permission from Simon T, et al. N Engl J Med. 2009;360(4): 11 11

12. CYP2C19 and Treatment with Clopidogrel Predominantly for PCI
Hazard Ratio (95% CI)
P Value
N=9,685
91.5% PCI
CVD, MI, or Stroke
1 or 2 CYP2C19 RFA vs Non-Carriers
1.57 ( )
0.006
1 CYP2C19 RFA vs Non-Carriers
1.55 ( )
0.01
2 CYP2C19 RFA vs Non-Carriers
1.76 ( )
0.002
1 CYP2C19 RFA vs Non-Carriers
2 CYP2C19 RFA vs Non-Carriers
2.67 ( )
3.97 ( )
<0.001
0.001
Stent Thrombosis
1 or 2 CYP2C19 RFA vs Non-carriers
2.81 ( )
<0.0001
N=5,894
1.0 2 5 10
Risk Lower with
CYP2C19 Variant
Risk Higher with
CYP2C19 Variant
Mega JL, Simon T, Collet JP et al.
JAMA 2010;304(16):
RFA=reduced-function allele

14. CURE Genetics Substudy
No association seen between CYP2C19 and outcomes in clopidogrel arm.
BUT, patients treated conservatively (only ~15% rate of PCI).
Pare et al. NEJM 2010; 363(18): 14

15. CYP2C19 and Treatment with Clopidogrel
CVD, MI, or Stroke:
Carriers of 1 or 2 CYP2C19 Variants vs Non-Carriers
Est. Hazard Ratio (95% CI)
Meta-Analysis (91.5% PCI)
1.57 ( )
PLATO (66% planned PCI)
Meta-Analysis + PLATO
1.43 ( )
CHARISMA (stable CAD or risk factors)
CURE (15.5% PCI)
Meta-Analysis + PLATO + CURE + CHARISMA
1.32 ( )
0.5
1.0
1.5
3.0
Risk Lower with
CYP2C19 Variant
Risk Higher with
CYP2C19 Variant
Mega JL, Simon T, Collet JP et al.
JAMA 2010;304(16):

16. Clopidogrel Reloading Among Genetic Carriers
Bonello et al JACC 2010

17. Study Design R Clopidogrel Dose A Clopidogrel Dose B Clopidogrel
Schedule
0 weeks
2 weeks
4 weeks
6 weeks
8 weeks
Visit 1
Visit 2
Visit 3
Visit 4
Visit 5
Stable CAD Patients on Clopidogrel 75 mg per day
(>4 Weeks and <6 Months Post-ACS or PCI)
Resume Pre-study Antiplatelet Medication R
Clopidogrel
Dose A
Clopidogrel
Dose B
Clopidogrel
Dose C
Clopidogrel
Dose D
Genetic Sample
Platelet Function Testing
(VASP & VerifyNow)
Platelet Function Testing
(VASP & VerifyNow)
Platelet Function Testing
(VASP & VerifyNow)
Platelet Function Testing
(VASP & VerifyNow)
Platelet Function Testing
(VASP & VerifyNow) 17

18.  Clopidogrel in CYP2C19*2 Heterozygotes
vs. 75 mg in Non-Carriers
Non-
Carriers
CYP2C19*2
Heterozygotes
PRUdiff +61
P<0.001
PRUdiff +24
P=0.02
PRUdiff -10
P=0.31
PRU
PRUdiff -37
P<0.001
Clopidogrel Daily Dose (mg)
Squares represent the means and vertical lines the 95% confidence intervals. Differences are reported as least squares differences.

19. Platelet Reactivity with  Clopidogrel
Non-
Carriers
CYP2C19*2
Heterozygotes
CYP2C19*2
Homozygotes
PRU
Clopidogrel Daily Dose (mg)
Squares represent the means and vertical lines the 95% confidence intervals.

20. Alternative Treatments: Pharmacodynamics
Clopidogrel
Prasugrel
100
Storey RF, et al. JACC 2010; 122(11):
Clopidogrel
Ticagrelor
100
200
300
400
500
Peak
235
PRU 80 60
IPA (%) 40 20
Clopidogrel Responder
Clopidogrel Non-responder
*Responder = 25% IPA at 4 and 24 h
-20
Brandt JT et al., Am Heart J 2007;153:e9-e16.

21. TRITON-TIMI 38 Genetic Substudy
1477 Pts w/ ACS and Planned PCI Clopidogrel
1466 Pts w/ ACS and Planned PCI
Prasugrel
CYP2C19 Reduced-Function Allele Carriers
Non-carriers of a CYP2C19
reduced function allele
Non-carriers
Carriers
CV Death, MI, or Stroke (%)
CV Death, MI, or Stroke (%)
HR 1.53 (95% CI )
P=0.014
P=0.046 for interaction between benefit of prasugrel vs. clopidogrel and CYP2C19 genotype
Mega JL, Close SL, Wiviott SD et al. Circulation 2009; 119:
Matetzky S, Shenkman B, Guetta V, et al. Clopidogrel resistance is associated with increased risk of recurrent atherothrombotic events in patients with acute myocardial infarction. Circulation. 2004;109:

22. PLATO Genetic Substudy: Ticagrelor vs Clopidogrel
CYP2C19 non-carriers
14% RRR, P=NS 1.2% abs Δ, NNT 84
CYP2C19 LOF Carriers
23% RRR, P= % abs Δ, NNT 39
Pinteraction=0.46
At 30 days:
4% RRR in non-carriers vs.
27% RRR in CYP2C19 LOF carriers
Wallentin L, et al. Lancet 2010; 376(9749):1320-8

23. Clopidogrel Label
Tests are available to identify a patient's CYP2C19 genotype and can be used as an aid in determining therapeutic strategy.
Consider alternative treatment or treatment strategies in patients identified as CYP2C19 poor metabolizers.
Note increase or alternative agents

24. ACCF/AHA Clinical Alert Approaches to the FDA Boxed Warning
Recommendations
Follow existing ACCF/AHA guidelines for antiplatelet therapy
Use clinical judgment to assess importance of clopidogrel response variability for the individual patient
Be aware that genetic variability in CYP enzyme alters clopidogrel metabolism
Areas of uncertainty
Information regarding predictive value of pharmacogenomic testing is limited
Evidence base is insufficient to recommend routine genetic or platelet function testing
PPI = proton pump inhibitor Holmes DR Jr, et al. Circulation. 2010;122:

25. Nissen, S JAMA 2011
“Overall, no significant association between genotype and cardiovascular events.”
--Holmes, MV et al JAMA 2011

26. Conservatively managed
Magnitude of PGx Interaction Will Depend on Relative Benefit of Clopidogrel
85% Risk Reduction
Conservatively managed
Invasively managed
0.14
Placebo
HR 1.25
HR 0.80
Aspirin Monotherapy
0.12
HR 6.67
HR 0.15
0.10
0.08
Clopidogrel
CV Death, MI, Stroke
0.06
0.04
Dual Antiplatelet Therapy
0.02
0.0 3 6 9 12
Months of follow-up
CURE. NEJM 2001;345:
STARS. NEJM 1998; 339: 1665.

27. CYP2C19 and Treatment with Clopidogrel Mega JL et al. & Sabatine MS.
CVD, MI, or Stroke:
Carriers of 1 or 2 CYP2C19 Variants vs Non-Carriers
Est. Hazard Ratio (95% CI)
Meta-Analysis (91.5% PCI)
1.57 ( )
PLATO Invasive Strategy (77% PCI)
PREDOMINANTLY INVASIVE
1.48 ( )
P heterogeneity = 0.013
CURE (15.5% PCI)
CHARISMA (stable CAD or risk factors)
PLATO Conservative Strategy (21% PCI)
PREDOMINANTLY CONSERVATIVE
0.98 ( )
0.5
1.0
1.5
3.0
Mega JL et al. & Sabatine MS.
JAMA 2010;304:1821
Risk Lower with
CYP2C19 Variant
Risk Higher with
CYP2C19 Variant
Wallentin. Lancet 2011; 377:637

28. Ready for Prime Time? Little value for PON-1 or ABCB1 at this time
CYP 2C19 Testing
Associated with less metabolism of clopidogrel
Associated with less platelet inhibition
Associated with worse clinical outcomes in ACS with PCI on clopidogrel
Not associated with worse outcomes on prasugrel or ticagrelor
Major outcomes trials missing, but strong associative evidence suggests value to use