Online Appendix for the following JACC article
TITLE: Reduction in Platelet Reactivity With Prasugrel 5 mg in Low-Body-Weight Patients Is Noninferior to Prasugrel 10 mg in
Higher-Body-Weight Patients: Results From the FEATHER Trial
AUTHORS: David Erlinge, MD, PhD, Jurrien Ten Berg, MD, PhD, David Foley, MD, Dominick J. Angiolillo, MD, PhD, Henrik
Wagner, MD, Patricia B. Brown, BSN, RN, Chunmei Zhou, PhD, Junxiang Luo, PhD, Joseph A. Jakubowski, PhD, Brian Moser, MS,
David S. Small, PhD, Thomas Bergmeijer, MD, Stefan James, MD, PhD, Kenneth J. Winters, MD
Supplemental Table 1. Pharmacodynamic measures in LBW patients treated with 5-mg prasugrel and in HBW treated with
10-mg prasugrel during period 1.
LBW
HBW
Adjusted
Prasugrel 5mg
Prasugrel 10mg
p-value
N=33
N=37
Measure
N
32
37
Mean (SD)
48.10 (13.89)
47.92 (15.18)
0.087
MPA to 20 µM ADP
MPA to 5 µM ADP
∆MPA to 20 µM ADP
∆MPA to 5 µM ADP
LS mean difference (95% CI)
N
Mean (SD)
5.52 (-0.82, 11.86)
32
37
36.12 (14.19)
38.67 (14.56)
LS mean difference (95% CI)
N
Mean (SD)
2.21 (-2.69, 7.11)
32
27.18 (13.40)
LS mean difference (95% CI)
N
32
37
30.01 (16.46)
0.371
0.087
-5.52 (-11.86, 0.82)
37
0.371
Mean (SD)
IPA to 20 µM ADP
IPA to 5 µM ADP
RPA to 20 µM ADP
RPA to 5 µM ADP
IRPA to 20 µM ADP
IRPA to 5 µM ADP
VN-P2Y12
(device reported %)
VN-P2Y12
(PRU)
VASP PRI
31.15 (10.47)
33.90 (9.88)
LS mean difference (95% CI)
N
Mean (SD)
-2.21 (-7.11, 2.69)
32
36.00 (17.09)
LS mean difference (95% CI)
N
Mean (SD)
-6.91 (-16.16, 2.33)
32
37
47.37 (17.34)
47.81 (14.27)
LS mean difference (95% CI)
N
Mean (SD)
-3.63 (-10.84, 3.57)
31
28.51 (17.30)
37
37.28 (24.69)
37
29.11 (21.66)
LS mean difference (95% CI)
N
Mean (SD)
31
13.75 (13.08)
LS mean difference (95% CI)
N
Mean (SD)
0.31 (-5.11, 5.73)
31
37
61.63 (22.60)
61.99 (31.46)
LS mean difference (95% CI)
N
Mean (SD)
-8.21 (-21.04, 4.62)
LS mean difference (95% CI)
N
Mean (SD)
0.140
0.317
0.220
5.55 (-3.41, 14.52)
31
79.48 (18.25)
37
18.11 (16.38)
37
75.82 (18.99)
0.910
0.205
0.772
-1.12 (-8.80, 6.56)
32
58.9 (19.57)
34
67.1 (22.07)
LS mean difference (95% CI)
N
Mean (SD)
32
129.53 (62.14)
LS mean difference (95% CI)
N
Mean (SD)
28.64 (-0.31, 57.59)
32
36
33.54 (15.77)
27.79 (18.13)
0.075
-8.80 (-18.52, 0.92)
34
102.09 (69.49)
0.052
0.196
LS mean difference (95% CI)
5.49 (-2.91, 13.89)
Abbreviations: ADP=adenosine diphosphate; CI=confidence interval; HBW=higher body weight; IPA= inhibition of platelet
aggregation; IRPA= inhibition of residual platelet aggregation; LBW=low body weight; LS=least squares; MPA=maximum platelet
aggregation; PRI=platelet reactivity index; PRU=P2Y12 reaction units; RPA= residual platelet aggregation; VN-P2Y12=VerifyNow®
P2Y12; VASP=vasodilator-associated phosphoprotein.
Supplemental Table 2.
LBW
HBW
Prasugrel 5 mg
Prasugrel 10 mg
N=33
N=37
MPA to 20µM ADP >50%, n (%)
14 (43.8)
14 (37.8)
0.633
IPA to 20 µM ADP <20%, n (%)
6 (18.8)
6 (16.2)
1.000
RPA 5 µM ADP >14%, n (%)
9 (29.0)
18 (48.6)
0.137
VN-P2Y12 PRU >235, n (%)
1 (3.1)
1 (2.9)
1.000
VN-P2Y12 <15%, n (%)
2 (6.3)
1 (2.9)
0.608
VASP-PRI ≥50%, n (%)
4 (12.5)
5 (13.9)
1.000
p-value
Abbreviations: ADP=adenosine diphosphate; HBW=high body weight; IPA=inhibition of platelet
aggregation; LBW=low body weight; MPA=maximum platelet aggregation; PRI=platelet reactivity
index; PRU=P2Y12 reaction units; RPA=residual platelet aggregation.
Supplemental Methods
Trial Design
At screening (Visit 1), patients were weighed and categorized as either low body weight (<60 kg,
LBW) or higher body weight (>60 kg, HBW). At the end of the aspirin run-in phase, patients in
each cohort were randomized into two treatment sequences on a continued background of
aspirin. All LBW patients received prasugrel 5-mg during Period 1, were subsequently
randomized to either prasugrel 10-mg or clopidogrel 75-mg for Period 2, then were crossed over
to the alternate study dose of either clopidogrel 75-mg or prasugrel 10-mg for Period 3. All
HBW patients received prasugrel 10-mg for Period 1, received either prasugrel 5-mg or
clopidogrel 75-mg for Period 2, and were crossed over to the alternate treatment for Period 3.
Period 1 was conducted in a single-blind fashion (only patients were blinded to treatment) to
allow study investigators to monitor initial tolerability to treatment; Periods 2 and 3 were
conducted double-blind. Before proceeding to Period 2, LBW patients needed to have tolerated
the 5-mg prasugrel dose in Period 1 (with tolerability defined as an absence of a study drugrelated adverse event that resulted in interruption and/or discontinuation of study drug, per
investigator opinion). Daily study treatment in Periods 1, 2, and 3 consisted of three tablets, one
active treatment (prasugrel 5-mg, prasugrel 10-mg, or clopidogrel 75-mg), and two placebos to
match the other two study drugs. The study was performed at 5 clinical sites in 4 countries
(Ireland, the Netherlands, Sweden, and USA) from March 2010 to August 2011.
Participants
Key trial exclusion criteria included unstable CAD (defined as newly diagnosed, increased, or
resting angina; hospitalization for unstable angina or myocardial infarction within the prior 30
days; or percutaneous coronary intervention (PCI) or coronary artery bypass grafting (CABG)
within the prior 90 days), a history of refractory ventricular arrhythmias within the last 6 months
or prior implantation of a defibrillator device, congestive heart failure of New York Heart
Association class III or IV within 6 months prior to screening, uncontrolled hypertension
(systolic blood pressure >180 mm Hg or diastolic blood pressure >110 mm Hg at screening),
planned coronary revascularization or other surgical procedures planned within 60 days
following randomization, or a prior history or presence of significant bleeding disorders,
abnormal bleeding tendency, or coagulation disorders. Additionally, patients could not be
enrolled if they had used antiplatelet agents (excluding aspirin) within 10 days prior to screening,
had used (or planned to use) heparin, oral anticoagulants, or fibrinolytic agents within 30 days of
screening, or were being treated with nonsteroidal anti-inflammatory drugs or cyclooxygenase-2
inhibitors that could not be discontinued for the duration of the study.
Study Objectives and Measures
The primary objective of FEATHER was to compare MPA responses to 20 µM adenosine
diphosphate (ADP) by light transmission aggregometry (LTA) in LBW patients receiving
prasugrel 5-mg versus HBW patients receiving prasugrel 10-mg. Secondary pharmacodynamic
(PD) measures included MPA response to 5µM ADP, residual platelet aggregation (RPA),
inhibition of platelet aggregation (IPA), P2Y12 reaction units (PRU) as assessed by the
VerifyNow® P2Y12 (VN-P2Y12) assay, and vasodilator-associated stimulated phosphoprotein
(VASP) phosphorylation levels. VASP phosphorylation levels were expressed as the platelet
reactivity index, PRI. For LTA and VASP, samples were collected into citrate blood collection
tubes at baseline and during the predose trough at the end of Periods 1, 2 and 3 (Day 12 ± 2).
Citrated Greiner™ tubes were used for sample collection for the VN-P2Y12 assay at the same
time points. LTA (without adjustment of platelet count), VN-P2Y12, and VASP assays were
conducted as described in previous publications (1,2).
Plasma samples for pharmacokinetic (PK) analysis were collected at 0.5, 1, 2, 3, and 4 hours
following the first dose of each period and the last dose of Period 3, and prasugrel’s and
clopidogrel’s active metabolite concentrations were assayed as described in previous
publications (3,4). Resulting data were analyzed noncompartmentally using the log-linear
trapezoidal method of WinNonlin version 5.3, Model 200 (Pharsight, Cary, NC). The primary
parameter for analysis was the area under the concentration–time curve calculated through the
last quantifiable concentration up to 4 hours postdose, AUC(0-tlast).
Safety data included the recording of adverse events, clinical laboratory evaluations,
measurements of vital signs, electrocardiograms, and physical examinations.
Statistical Analysis
The primary non-inferiority analysis compared the median of MPA to 20 µM ADP for prasugrel
5-mg in LBW patients to the 75th percentile of the MPA for prasugrel 10-mg in HBW patients at
the end of Period 1. The upper limit of the one-sided 97.5% confidence interval (CI) of the
difference was estimated from resampling data with replacement through bootstrap methodology
and was compared with the pre-specified margin of 15 percentage points.
Based on the LTA data from four previous studies of prasugrel in aspirin-treated patients with
CAD (5,6,7,8), we assumed an 8 percentage point mean difference of MPA to 20 µM ADP
between prasugrel 5-mg in LBW patients and prasugrel 10-mg in HBW patients, an SD of 18%
for prasugrel 5-mg in LBW patients, and an SD of 12% for prasugrel 10-mg in HBW patients;
under these assumptions, having data for the primary endpoint on 33 patients in each arm
provides >80% power for the non-inferiority test of the primary endpoint at a one-sided 2.5%
significance level.
Pre-specified HPR thresholds were: MPA to 20 μM ADP >50% (9); inhibition of platelet
aggregation (IPA) to 20 μM ADP <20% (10) ; RPA to 5 μM ADP >14% (11); VN-P2Y12
PRU>235 (12); VN-P2Y12, device-reported inhibition <15% (13); VASP based PRI ≥50% (14).
Within each BW cohort, the comparisons between treatment groups on PD response were
performed using a mixed-effect model with repeated measure analysis on PD response after 12 ±
2 days of daily dosing were performed by a mixed-effect model with repeated measure analysis
with treatment (prasugrel 5-mg, prasugrel 10-mg and clopidogrel 75-mg), study site, period,
treatment sequence and the baseline value as the fixed effects, and patient as a random effect.
Within each BW cohort, rate of HPR was compared between treatment groups using a
generalized linear model with repeated measures, through generalized estimating equations.
All statistical analyses were performed using SAS version 9.1 (Cary, North Carolina USA).
1. Jakubowski JA, Payne CD, Li YG, Brandt JT, Small DS, Farid NA, Salazar DE, Winters KJ.
The use of the VerifyNow P2Y12 point-of-care device to monitor platelet function across a range
of P2Y12 inhibition levels following prasugrel and clopidogrel administration. Thromb Haemost
2008: 99(2):409-15
2. Jakubowski JA, Bourguet N, Boulay-Moine D, et al. Comparison of a new ELISA assay with
the flow cytometric assay for platelet vasodilator-associated stimulated phosphoprotein (VASP)
phosphorylation in whole blood to assess P2Y12 inhibition. Thromb Haemost 2011: 107(2)
3. Farid NA, McIntosh M, Garofolo F, et al. Determination of the active and inactive metabolites
of prasugrel in human plasma by liquid chromatography/tandem mass spectrometry. Rapid
Commun Mass Spectrom 2007; 21(2):169-179.
4. Takahashi M, Pang H, Kawabata K, et al. Quantitative determination of clopidogrel active
metabolite in human plasma by LC-MS/MS. J Pharm Biomed Anal 2008; 48:1219-1224.
5. Jernberg T, Payne CD, Winters KJ, et al. Prasugrel achieves greater inhibition of platelet
aggregation and a lower rate of non-responders compared with clopidogrel in aspirin-treated
patients with stable coronary artery disease. Eur Heart J. 2006;27(10):1166-1173.
6. Wallentin L, Varenhorst C, James S, et al. Prasugrel achieves greater and faster P2Y12
receptor-mediated platelet inhibition than clopidogrel due to more efficient generation of its
active metabolite in aspirin-treated patients with coronary artery disease. Eur Heart J 2008;
29(1):21-30.
7. Wiviott SD, Trenk D, Frelinger AL, et al. Prasugrel compared with high loading- and
maintenance-dose clopidogrel in patients with planned percutaneous coronary intervention: the
Prasugrel in Comparison to Clopidogrel for Inhibition of Platelet Activation and AggregationThrombolysis in Myocardial Infarction 44 trial. Circulation 2007; 116(25):2923-2932.
8. Montalescot G, Sideris G, Cohen R, et al. Prasugrel compared with high-dose clopidogrel in
acute coronary syndrome. Thromb Haemost 2010; 103(1):213-223.
9. Angiolillo DJ, Shoemaker SB, Desai B, et al. Randomized comparison of a high clopidogrel
maintenance dose in patients with diabetes mellitus and coronary artery disease: results of the
Optimizing Antiplatelet Therapy in Diabetes Mellitus (OPTIMUS) study. Circulation 2007;
115(6):708-716
10. Weerakkody GJ, Brandt JT, Payne CD, et al. Clopidogrel poor responders: an objective
definition based on Bayesian classification. Platelets 2007; 18(6):428-435.
11. Hochholzer W, Trenk D, Bestehorn H-P, et al. Impact of the degree of peri-interventional
platelet inhibition after loading with clopidogrel on early clinical outcome of elective coronary
stent placement. J Am Coll Cardiol 2006; 48(9):1742-1750.
12. Price MJ, Endemann S, Gollapudi RR, Valencia R, et al. Prognostic significance of postclopidogrel platelet reactivity assessed by a point-of-care assay on thrombotic events after drugeluting stent implantation. European Heart Journal 2008; 29(8):992–1000.
13. Cuisset T, Hamilos M, Sarma J, et al. Relation of low response to clopidogrel assessed with
point-of-care assay to periprocedural myonecrosis in patients undergoing elective coronary
stenting for stable angina pectoris. Am J Cardiol 2008; 15(12):1700-1703
14. Barragan P, Bouvier JL, Roquebert PO, et al. Resistance to thienopyridines: clinical detection
of coronary stent thrombosis by monitoring of vasodilator-stimulated phosphoprotein
phosphorylation. Cathet Cardiovasc Intervent 2003; 59:295-302.