Role of Genotyping and Point-of-Care of Testing in Clopidogrel, Prasugrel, and Ticagrelor Ron Waksman, MD Ron Waksman, MD Professor of Medicine (Cardiology), Georgetown University Associate Director, Division of Cardiology, Washington Hospital Center
UNDERSTANDING ANTIPLATELET RESPONSE VARIABILITY Pharmacogenomics, Metabolism, and Platelet Reactivity
Antiplatelet Drug Resistance / Response Variability: An Emerging Clinical Problem
Individual Response Variability to Dual Antiplatelet Therapy in the Steady State Phase of Treatment 20 ents er of Patie Numbe 15 10 5 Bleeding risk Ischemic risk 0 2.5 75 7.5 12.5 17.5 22.5 27.5 32.5 37.5 42.5 47.5 52.5 57.5 5 62.5 67.5 72.5 77.5 82.5 % Platelet Aggregation (LTA-ADP ADP 20µmol/L) 87.5 92.5 97.5 Adapted from Angiolillo DJ et al. Am J Cardiol. 2006;97:38-43.
Baseline Platelet Reactivity* Determines Clinical Outcomes** Following Coronary Stenting 10 1.0 0.9 Low Reactivity Group 0.8 0.7 High Reactivity Group 06 0.6 0.5 P=0.01 P=0.006 P=0.043 0 100 200 300 Time (Days) Kabbani SS et al. Am J Cardiol. 2003;91:876-878. * Fibrinogen binding in response to 0.2 µm ADP ** Composite MI, UR, Revascularization
Non-responsiveness to Clopidogrel Is a Predictor of Stent Thrombosis in Patients Receiving a DES Definite or prob bable stent throm bosis 100 98 96 94 92 90 88 86 84 82 Responders Nonresponders 98±1 Log rank P <0.001 91±3 80 0 30 60 90 120 150 180 Time (days) In 804 patients t undergoing stenting, stent thrombosis was found to be more prevalent in patients with post-treatment platelet aggregation 70% in response to 10 µm ADP The incidence of stent thrombosis was 8.6% in nonresponders and 2.3% in responders (P <0.001). Buonamici P et al. J Am Coll Cardiol. 2006;49:2312-2317.
Interindividual Variability in Platelet Reactivity to Clopidogrel in Patients Undergoing Coronary Stenting 2 Hours 24 Hours 24 Resistance Resistance = 63% Resistance 20 Resistance = 31% tients (%) Pa 12 10-30 (-20,-10] (-30,-20] (-10,0] (0,10] (10,20] (20,30] (30,40] (40,50] (50,60] >60-30 (-20,-10] (-30,-20] (-10,0] (0,10] (10,20] (20,30] (40,50] (30,40] (50,60] >60 22 5 Days Resistance Resistance = 31% 28 30 Days Resistance = 15% Pa atients (%) 11 14 Resistance -10 (-10,0] (0,10] (10,20] (20,30] (30,40] (40,50] (50,60] >60 Aggregation (%) -30 (-20,-10] (0,10] (20,30] (40,50] >60 (-30,-20] (-10,0] (10,20] (30,40] Aggregation (%) (50,60] Gurbel PA et al. Circulation. 2003;107:2908-2913.
Platelet Function Tests Platelet Aggregation Flow Cytometry Point-of-care Light transmittance aggregometry (LTA) Impedance platelet aggregation GPIIb/IIIa receptor activation P-selectin expression Monocyte-platelet aggregates Vasodilator-associated associated stimulated phosphoprotein (VASP) Ultegra rapid platelet function analyzer (VerifyNow) Thromboelastagraph (TEG) PFA-100 Plateletworks Genetic testing Cone and plate(let) analyzer (IMPACT) gold standard
How does the VerifyNow Assay Work? Whole blood, closed-tube sampling with no pipetting required Assay results in less than 5 minutes (assay time) Good correlation with LTA and VASP Light Source Mixing Chamber Agonists: Aspirin Assay AA P2Y12 assay ADP + PGE1 GpIIbIIIa assay iso-trap Agonist Platelets in whole blood maximally activated by agonist in mixing chamber + Fibrinogen-coated beads Agglutinated beads aggregate in clusters
GRAVITAS Trial Design Gauging Responsiveness with a VerifyNow Assay Impact on Thrombosis and Safety This trial is designed to evaluate whether tailored clopidogrel therapy, using a point-of-care platelet function assay, reduces major adverse cardiovascular events after DES implantation Stable angina/ischemia or non-st-elevation acute coronary syndrome undergoing PCI with DES Not High Residual Platelet Reactivity on Clopidogrel Therapy 12 to 24 hours Post PCI High Residual Platelet Reactivity on Clopidogrel Therapy 12 to 24 hours Post PCI Standard Dosing Clopidogrel 75 mg once daily x 6 months High Dose Clopidogrel 450 mg loading dose followed by 150 mg once daily x 6 months The primary end point is the time to first occurrence of cardiovascular death, nonfatal myocardial infarction, or definite/probable stent thrombosis. Price MJ et al. Am Heart J. 2009;157:818-824.
Power Analysis: Sample Size Estimate Assumptions: An event rate of 5% in patients on standard-dose clopidogrel at 6-months 50% risk reduction with high-dose clopidogrel 2200 patients needed to provide 80% power at a two-sided 0.05 significance level
GRAVITAS Patient Flow 5429 patients screened with VerifyNow P2Y12 12-2424 hours post-pci 2214 (41%) with high residual platelet reactivity (PRU 230) 3215 (59%) without high residual platelet reactivity (PRU < 230) Clopidogrel High Dose N=1109 Clopidogrel Standard Dose N=1105
Primary Endpoint: CV Death, MI, Stent Thrombosis Observed event rates are listed; P value by log rank test.
Bleeding Events: Safety Population Severe or life-threatening: Fatal bleeding, intracranial hemorrhage, or bleeding that causes hemodynamic compromise requiring blood or fluid replacement, inotropic support, or surgical intervention Moderate: Bleeding that leads to transfusion but does not meet criteria for severe bleeding P by log rank test; observed event rates listed. HD, high-dose; SD, standard dose
GRAVITAS Patient Flow: Secondary Analysis 5429 patients screened with VerifyNow P2Y12 12-2424 hours post-pci 2214 (41%) with high residual platelet reactivity (PRU 230) 3215 (59%) without high residual platelet reactivity (PRU < 230) Clopidogrel High Dose N=1109 Clopidogrel Standard d Dose N=1105 Clopidogrel Standard Dose N=586 Random selection Non-Randomized Comparison
Baseline Characteristics: Non-Randomized Comparison Characteristic SD SD Not High RPR High RPR N=1105 N=586 Residual platelet reactivity, 283 PRU 151 PRU (105 median (IQR) <0.001 (255-321) - 191) Age, years 64 ± 11 62± 10 <.0001 Male sex 65% 80% <0.001 Diabetes Mellitus 47% 29% <0.001001 Body mass index (median) 31 29 <0.001 Cr Cl< 60 ml/min 42% 27% <0.001 Proton pump inhibitor 30% 20% <0.001 Indication for PCI 0.41 Stable angina or ischemia 60% 56% UA, no ST depression 24% 28% NSTE-ACS UA, ST-dep, biomarker (-) 5% 5% Cardiac biomarker (+) 10% 11% p
Secondary Comparison: High vs. Not High Reactivity Observed event rates are listed. P value by log-rank test.
CV Events and Post-PCI PRU In Pts With High and Not High Reactivity Treated With Standard-Dose Clopidogrel 500 PRU 12-24 hrs post-pci 400 300 200 Red dots: patients with CV death, MI, or ST 230 PRU 100 0 N=1105 N= 586 ITT population High Residual Reactivity Not High Residual Reactivity
GRAVITAS: Possible Explanations Underpowered: patients low-risk, low event rates. Given HR of 1.01 after 2200 patients, t unlikely l that t a larger trial would show a clinically meaningful benefit Pharmacodynamic effect of the intervention was too weak? Stronger intervention, goal-directed therapy with serial measurements merit study Platelet reactivity is a non-modifiable risk factor? To be further examined in TARGET-PCI, ARCTIC, TRIGGER-PCI VerifyNow results not predictive of risk? However, at least 7 studies involving more than 3,000 patients demonstrate a correlation with MACE
GRAVITAS does not support a treatment strategy of high-dose clopidogrel in low-risk patients with high reactivity identified by a single platelet function test after PCI.
UNDERSTANDING PLATELET GENOMICS Pharmacogenomics, Metabolism, and Platelet Reactivity
Mechanism of Action of Prasugrel Bhatt DL. N Engl J Med. 2009;361:940-942.
Ticagrelor: Pharmacology A P2Y 12 purinoceptor antagonist t Does not require cytochrome P450 metabolic activation to exert its inhibitory effects on platelet aggregation No active metabolite Rapid onset of action Reversibly binds to the P2Y 12 receptor Potential advantage if needing to discontinue therapy due to surgery Compared with clopidogrel, produces a greater and more consistent inhibition of ADP-induced platelet aggregation Adapted from: Owen RT et al. AZD6140. Drugs of the Future. 2007;32:845-853.
Effects of CYP2C19*2 and *17 Combined N=445 patients; 24 hours post 600-mg clopidogrel loading dose Sl Slow Fast Frequency Normal 3% PRI=platelet reactivity index; VASP=vasodilator-stimulated phosphoprotein. Frére C, et al. J Thromb Haemost. 2009;7(8):1409-1411. 3.5%
CYP2C19 and CVD, MI, or Stroke N=1477 ACS/PCI Subjects Treated with Clopidgrel in TRITON-TIMI 38 CV Death, MI, or Stroke (%) 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 CYP2C19 Reduced-Function Allele Carriers Non-carriers Hazard Ratio 1.53 (95% CI 1.07-2.19) 219) P=0.014 12.1 8.0 0 30 90 180 270 360 450 Days After Randomization Number at Risk: Non-Carrier 1064 1009 999 980 870 755 542 Carrier 395 364 360 348 306 270 181 (%) finite or Probable Stent Thrombosis ( Def 4 3 2 1 0 Hazard Ratio 3.09 (95% CI 1.19-8.00) P=0.015 CYP2C19 Reduced-Function Allele Carriers Non-carriers 2.6 0.8 0 30 90 180 270 360 450 Days After Randomization Number at Risk: Non-Carrier 1014 1004 1001 989 885 765 547 Carrier 375 368 366 359 316 279 186 * Carriers ~30% of the population Mega JL, Close S, Wiviott SD et al. N Eng J Med. 2009; 360:354-62.
CYP2C19*2 and Outcomes Cumulative Event-Free (Death, MI, Urgent Revasc) Surviv al (%) Collet JP et al. Lancet 2009;373:309-317. Stent Thrombosis: (HR 6.02, 95% CI 1.81-20.04, P=0.0009)
CYP2C19*2 and Outcomes 1.98 (1.10-3.58) 1.00 0.69 (0.51-0.93) P=0.003 Simon T et al. N Eng J Med. 2009; 360:363-375.
CYP2C19 and Treatment with Clopidogrel Predominantly for PCI CVD, MI, or Stroke N=9,685 91.5% PCI Hazard Ratio (95% CI) P Value 1 or 2 CYP2C19 RFA vs Non-Carriers 157(1132 1.57 (1.13-2.16) 16) 0.006006 1 CYP2C19 RFA vs Non-Carriers 1.55 (1.11-2.17) 0.01 2 CYP2C19 RFA vs Non-Carriers 1.76 (1.24-2.50) 0.002 Stent Thrombosis N=5,894 1 or 2 CYP2C19 RFA vs Non-carriers 2.81 (1.81-4.37) <0.0001 1 CYP2C19 RFA vs Non-Carriers 2.67 (1.69-4.22) <0.001 2 CYP2C19 RFA vs Non-Carriers 3.97 (1.75-9.02) 0.001 RFA=reduced-function allele 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):1821-30.
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):1704-14.
Magnitude of PGx Interaction Will Depend on Relative Benefit of Clopidogrel l Conservatively managed Invasively managed 0.14 012 0.12 Placebo Aspirin Monotherapy CV De eath, MI, Stroke 0.10 0.08 Clopidogrel 85% Risk Reduction 0.06 0.02 20% Risk Reduction 0.04 Dual Antiplatelet Therapy 0.0 0 3 6 9 12 Months of follow-up CURE. NEJM 2001;345:494-502 STARS. NEJM 1998; 339: 1665.
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 (1.13-2.16) PLATO (66% planned PCI) Meta-Analysis + PLATO 1.43 (1.11-1.84) CURE (15.5% PCI) CHARISMA (stable CAD or risk factors) Meta-Analysis + PLATO + CURE + CHARISMA 1.32 (1.07-1.63) 0.5 Risk Lower with CYP2C19 Variant 1.0 1.5 3.0 Risk Higher with CYP2C19 Variant Mega JL, Simon T, Collet JP et al. JAMA 2010;304(16):1821-30.
Alternative Treatments: Pharmacodynamics 100 Clopidogrel Prasugrel 500 80 400 60 IPA (% %) 40 PRU 300 235 PRU 200 20 0 Clopidogrel Responder Clopidogrel Non-responder 100-20 *Responder = 25% IPA at 4 and 24 h 0 Clopidogrel l Ticagrelor Peak Brandt JT et al., Am Heart J 2007;153:e9-e16. Storey RF, et al. JACC 2010; 122(11):1056-67.
TRITON-TIMI 38 Genetic Substudy 1477 Pts w/ ACS and Planned PCI Clopidogrel 1466 Pts w/ ACS and Planned PCI Prasugrel or Stroke (% %) I, or Stroke (%) CV Death, MI CV Death, MI, 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Number at Risk: Non-Carrier Carrier CYP2C19 Reduced-Function Carriers Allele Carriers Non-carriers HR 1.53 (95% CI 1.07-2.19) 219) P=0.014 Hazard Ratio 1.53 (95% CI 1.07-2.19) 219) 12.1 8.0 0 30 90 180 270 360 450 Days After Randomization 1064 1009 999 980 870 755 542 395 364 360 348 306 270 181 or Stroke (% %) I, or Stroke (%) CV Death, CV Death, MI, M 14 13 12 11 10 9 8 7 6 5 4 3 2 1 0 Number at Risk: Non-Carrier Carrier Non-carriers of a CYP2C19 reduced function allele Non-carriers Carriers Carriers Hazard Ratio 0.89 (95% CI 0.60-1.31) P=0.27 9.8 8.5 0 30 90 180 270 360 450 Days After Randomization at o 1048 991 982 951 849 750 541 407 383 376 364 320 276 188 P=0.046 for interaction between benefit of prasugrel vs. clopidogrel and CYP2C19 genotype Mega JL, Close SL, Wiviott SD et al. Circulation 2009; 119:2553-2560.
http://www.fda.gov/drugs/drugsafety/postmarketdrugsafetyinformationforpatientsandproviders/ucm203888.htm#ds
STENT THROMBOSIS (n=4905) Odds Ratio, fixed model Bilateral CI, 95% for trials, 95% for MA 2C19*2 better 2C19*2 worse 2C19*2 2C19*1 Mega et al. (0.26) Collet et al. (0.15) Giusti et al. (0.34) 10/375 8/1014 8/73 4/186 13/247 11/525 Sibbing et al. (0.24) 10/680 7/1805 Total 41/1375 30/3530 OR 3.45 95% CI: 2.14 5.57, p<0.001, p het =0.78 Odds Ratio Rti events / size J Am Coll Cardiol 2010; 56(2):134-143
Collaborative Meta analysis: CYP2C19 and Stent Thrombosis in Patients on Clopidogrel l Carriers vs Noncarriers Heterozygotes vs Wild Type Homozygotes vs Wild Type Risk Ratio (95% CI) P value 2.81 (1.81 4.37) <.0001 2.67 (1.69 4.22) <.0001 3.97 (1.75 9.02) <.001 N = 5772 0.5 1.0 15.0 Risk Lower With Risk Higher With 5 CYP2C19 Variant CYP2C19 Variant Mega JL. American Heart Association; November 2009; Orlando, Florida.
Pharmacogenomics of Antiplatelet Therapies Carriers vs Non-carriers of a Reduced-function CYP2C19 Allele CLINICAL OUTCOMES Prasugrel 0.89 P=0.27 More Ischemic Events Less Ischemic Events 0.046 Clopidogrel 1.53 P=0.01 3.5 3.0 2.5 2.0 1.5 1.0 0.5 Odds Ratio Modified from: Mega JL et al. Circulation. 2009;119:2553-2560. * Data adapted from: Mega JL et al. N Engl J Med. 2009;360:354-362.
Event-free Survival Over 1 Year of Follow-up In Patients Treated with Clopidogrel Following PCI* No. of CYP2C19*2 alleles CYP2C19*2 variant accounts for 12% 0 1 aggregation to ADP. clopidogrel response variation of platelet ng Event % Experienci 50 40 30 20 10 All patients Patients taking clopidogrel at time of event Patients not taking clopidogrel at time of event 0 90 180 270 360 0 90 180 270 360 0 90 180 270 360 Days Days Days No. at risk No. of CYP2C19*2 alleles 0 158 154 150 144 143 66 64 62 58 57 92 90 88 87 86 1 67 61 56 53 50 27 23 18 17 16 40 38 38 36 33 * CYP2C19*2 variant accounts for 12% of clopidogrel response variation of platelet aggregation to ADP Shuldiner A et al. JAMA. 2009;302:849-858.
TRITON-TIMI 38 ABCB1 and CYP2C19 Polymorphisms Diminish Clopidogrel Antiplatelet Effect Both polymorphisms = highest risk 14 MI, No polymorphisms = lowest risk Cardiov vascular death, or stroke (%) p=0 0018 across genotype. 12 10 8 6 4 2 0 CYP2C19 reduced-function carrier and ABCB1 3435 TT CYP2C19 reduced-function non-carrier and ABCB1 3435 TT CYP2C19 reduced-function carrier and ABCB1 3435 CC/CT CYP2C19 reduced-function non-carrier and ABCB1 3435 CC/CT 0 30 60 90 120 150 180 210 240 270 300 330 360 390 420 450 CC = ABCB1 normal function; C T = ABCB1 reduced function; Post-hoc analysis. Mega JL, et al. Lancet. 2010;376:1312-1319. Days from randomisation 13 6 12 6 11 5 6 3
Genetic and Platelet Function Testing ENVIRONMENT GENOME TRANSCRIPTOME PROTEOME PHENOTYPE transcription translation post-translation modification ~2 10 4 genes ~10 7 SNPs >10 5 transcripts ~10 5 proteins ~10 6 modified proteins GENETIC TESTING Fixed Lifelong impact Easy to assess Distanced from phenotype PLATELET FUNCTION TESTING Proximal to phenotype Captures environmental & genetic variability More difficult to assess Varies with time
Clopidogrel Reloading Among Genetic Carriers Bonello et al JACC 2010
Tailoring Antiplatelet Therapy Based on Platelet Function Testing and Genotyping Paul Gurbel, August 2010 "The bottom line is we have no prospective studies at this time that alteration of therapy based on genotype or phenotype really affects patient outcomes White Paper, JACC 2010 (Bonello/Gurbel l et al) However, until the results of large scale trials of personalized antiplatelet therapy are available, the routine use of platelet function measurements in the care of patients with cardiovascular disease cannot be recommended 2010 ACCF/ACG/AHA Expert Consensus Document on the Concomitant Use of PPIs and Thienopyridines "The role of either pharmacogenomic testing or platelet-function testing in managing therapy with thienopyridines and PPIs has not yet been established"
Conclusions The CYP2C19 reduced function genotypes are associated with worse outcomes in the setting of treatment with clopidogrel. Novel antiplatelets appear to be less so. ABCB1 and PON-1 may offer similar risk stratification. Genetics and platelet function appear to offer complementary information. Routine use of genetic and platelet function testing for alteration of therapy is not ready for prime time