Prescription Drug Information: Clopidogrel (Page 4 of 6)

14 CLINICAL STUDIES

14.1 Acute Coronary Syndrome

CURE The CURE study included 12,562 patients with ACS without ST-elevation (UA or NSTEMI) and presenting within 24 hours of onset of the most recent episode of chest pain or symptoms consistent with ischemia. Patients were required to have either ECG changes compatible with new ischemia (without ST-elevation) or elevated cardiac enzymes or troponin I or T to at least twice the upper limit of normal.

Patients were randomized to receive clopidogrel (300-mg loading dose followed by 75 mg once daily) or placebo, and were treated for up to one year. Patients also received aspirin (75 to 325 mg once daily) and other standard therapies such as heparin. The use of GPIIb/IIIa inhibitors was not permitted for three days prior to randomization.

The patient population was largely White (82%) and included 38% women, and 52% age ≥ 65 years of age. Only about 20% of patients underwent revascularization during the initial hospitalization and few underwent emergent or urgent revascularization.

The number of patients experiencing the primary outcome (CV death, MI, or stroke) was 582 (9.3%) in the clopidogrel-treated group and 719 (11.4%) in the placebo-treated group, a 20% relative risk reduction (95% CI of 10% to 28%; p < 0.001) for the clopidogrel-treated group (see Table 4).

Table 4: Outcome Events in the CURE Primary Analysis
Outcome Clopidogrel (+ aspirin) *(n=6259) Placebo (+ aspirin) *(n=6303) Relative Risk Reduction (%) (95% CI)
*
Other standard therapies were used as appropriate.
The individual components do not represent a breakdown of the primary and co-primary outcomes, but rather the total number of subjects experiencing an event during the course of the study.

Primary outcome (Cardiovascular death, MI, stroke)

582 (9.3%)

719 (11.4%)

20% (10.3, 27.9) p < 0.001

All Individual Outcome Events:

CV death

318 (5.1%)

345 (5.5%)

7% (-7.7, 20.6)

MI

324 (5.2%)

419 (6.6%)

23% (11.0, 33.4)

Stroke

75 (1.2%)

87 (1.4%)

14% (-17.7, 36.6)

Most of the benefit of clopidogrel occurred in the first two months, but the difference from placebo was maintained throughout the course of the trial (up to 12 months) (see Figure 2).

Figure 2
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The effect of clopidogrel did not differ significantly in various subgroups, as shown in Figure 3. The benefits associated with clopidogrel were independent of the use of other acute and long-term cardiovascular therapies, including heparin/LMWH, intravenous glycoprotein IIb/IIIa (GPIIb/IIIa) inhibitors, lipid-lowering drugs, beta-blockers, and ACE-inhibitors. The efficacy of clopidogrel was observed independently of the dose of aspirin (75 to 325 mg once daily). The use of oral anticoagulants, non-study antiplatelet drugs, and chronic NSAIDs was not allowed in CURE.

Figure 3
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Figure 3 (cont)
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The use of clopidogrel in CURE was associated with a decrease in the use of thrombolytic therapy (71 patients [1.1%] in the clopidogrel group, 126 patients [2.0%] in the placebo group; relative risk reduction of 43%), and GPIIb/IIIa inhibitors (369 patients [5.9%] in the clopidogrel group, 454 patients [7.2%] in the placebo group, relative risk reduction of 18%). The use of clopidogrel in CURE did not affect the number of patients treated with CABG or PCI (with or without stenting) (2,253 patients [36.0%] in the clopidogrel group, 2,324 patients [36.9%] in the placebo group; relative risk reduction of 4.0%).

COMMIT In patients with STEMI, the safety and efficacy of clopidogrel were evaluated in the randomized, placebo-controlled, double-blind study, COMMIT. COMMIT included 45,852 patients presenting within 24 hours of the onset of the symptoms of myocardial infarction with supporting ECG abnormalities ( i.e. , ST-elevation, ST-depression or left bundle-branch block).

Patients were randomized to receive clopidogrel (75 mg once daily) or placebo, in combination with aspirin (162 mg per day), for 28 days or until hospital discharge, whichever came first.

The primary endpoints were death from any cause and the first occurrence of re-infarction, stroke or death.

The patient population was 28% women and 58% age ≥ 60 years (26% age ≥ 70 years). Fifty- five percent (55%) of patients received thrombolytics and only 3% underwent PCI.

As shown in Table 5 and Figure 4 and Figure 5 below, clopidogrel significantly reduced the relative risk of death from any cause by 7% (p=0.029), and the relative risk of the combination of re-infarction, stroke or death by 9% (p=0.002).

Table 5: Outcome Events in COMMIT
*
9 patients (2 clopidogrel and 7 placebo) suffered both a non-fatal stroke and a non-fatal MI.
Non-fatal MI and non-fatal stroke exclude patients who died (of any cause).

Event

Clopidogrel (+ aspirin) (N=22961)

Placebo (+ aspirin) (N=22891)

Odds ratio (95% CI)

p-value

Composite endpoint: Death, MI, or Stroke *

2121 (9.2%)

2310 (10.1%)

0.91 (0.86, 0.97)

0.002

Death Non-fatal MI Non-fatal Stroke

1726 (7.5%) 270 (1.2%) 127 (0.6%)

1845 (8.1%) 330 (1.4%) 142 (0.6%)

0.93 (0.87, 0.99) 0.81 (0.69, 0.95) 0.89 (0.70, 1.13)

0.029 0.011 0.33

Figure 4
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Figure 5
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The effect of clopidogrel did not differ significantly in various pre-specified subgroups as shown in Figure 6. The effect was also similar in non-prespecified subgroups including those based on infarct location, Killip class or prior MI history. Such subgroup analyses should be interpreted cautiously.

Figure 6
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14.2 Recent Myocardial Infarction, Recent Stroke, or Established Peripheral Arterial Disease

CAPRIE The CAPRIE trial was a 19,185-patient, 304-center, international, randomized, double-blind, parallel-group study comparing clopidogrel (75 mg daily) to aspirin (325 mg daily). To be eligible to enroll, patients had to have: 1) recent history of myocardial infarction (within 35 days); 2) recent histories of ischemic stroke (within 6 months) with at least a week of residual neurological signs; and/or 3) established peripheral arterial disease (PAD). Patients received randomized treatment for an average of 1.6 years (maximum of 3 years).

The trial’s primary outcome was the time to first occurrence of new ischemic stroke (fatal or not), new myocardial infarction (fatal or not), or other vascular death. Deaths not easily attributable to nonvascular causes were all classified as vascular.

Table 6: Outcome Events in the CAPRIE Primary Analysis
ClopidogrelAspirin
Patients n=9599 n=9586

Ischemic stroke (fatal or not)

438 (4.6%)

461 (4.8%)

MI (fatal or not)

275 (2.9%)

333 (3.5%)

Other vascular death

226 (2.4%)

226 (2.4%)

Total

939 (9.8%)

1020 (10.6%)

As shown in Table 6, clopidogrel was associated with a lower incidence of outcome events, primarily MI. The overall relative risk reduction (9.8% vs 10.6%) was 8.7%, p=0.045. Similar results were obtained when all-cause mortality and all-cause strokes were counted instead of vascular mortality and ischemic strokes (risk reduction 6.9%). In patients who survived an on-study stroke or myocardial infarction, the incidence of subsequent events was lower in the clopidogrel group.

The curves showing the overall event rate are shown in Figure 7. The event curves separated early and continued to diverge over the 3-year follow-up period.

Figure 7
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The statistical significance favoring clopidogrel over aspirin was marginal (p=0.045). However, because aspirin is itself effective in reducing cardiovascular events in patients with recent myocardial infarction or stroke, the effect of clopidogrel is substantial.

The CAPRIE trial enrolled a population that had recent MI, recent stroke, or PAD. The efficacy of clopidogrel relative to aspirin was heterogeneous across these subgroups (p=0.043) (see Figure 8). Nonetheless this difference may be a chance occurrence because the CAPRIE trial was not designed to evaluate the relative benefit of clopidogrel over aspirin in the individual patient subgroups. The benefit was most apparent in patients who were enrolled because of peripheral arterial disease and less apparent in stroke patients. In patients who were enrolled in the trial on the sole basis of a recent myocardial infarction, clopidogrel was not numerically superior to aspirin.

Figure 8
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