Abciximab clinical studies

Template:Abciximab Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]; Associate Editor(s)-in-Chief: Sheng Shi, M.D. [2], Pratik Bahekar, MBBS [3]

Clinical Studies

Abciximab has been studied in four Phase 3 clinical trials, all of which evaluated the effect of Abciximab in patients undergoing percutaneous coronary intervention (PCI): in patients at high risk for abrupt closure of the treated coronary vessel (EPIC), in a broader group of patients (EPILOG), in unstable angina patients not responding to conventional medical therapy (CAPTURE), and in patients suitable for either conventional angioplasty/atherectomy or primary stent implantation (EPILOG Stent; EPISTENT). Percutaneous intervention included balloon angioplasty, atherectomy, or stent placement. All trials involved the use of various, concomitant heparin dose regimens and, unless contraindicated, aspirin (325 mg) was administered orally two hours prior to the planned procedure and then once daily.

EPIC was a multicenter, double-blind, placebo-controlled trial of Abciximab in patients undergoing percutaneous transluminal coronary angioplasty or atherectomy (PTCA) who were at high risk for abrupt closure of the treated coronary vessel (7). Patients were allocated to treatment with: 1) Abciximab bolus plus infusion for 12 hours; 2) Abciximab bolus plus placebo infusion, or; 3) placebo bolus plus infusion. All patients received concomitant heparin (10,000 to 12,000 U bolus followed by an infusion for 12 hours).

The primary endpoint was the composite of death, myocardial infarction (MI), or urgent intervention for recurrent ischemia within 30 days of randomization. The primary endpoint event rates in the Abciximab bolus plus infusion group were reduced mostly in the first 48 hours and this benefit was sustained through 30 days (7), 6 months (8), and three years (9).

EPILOG was a randomized, double-blind, multicenter, placebo-controlled trial which evaluated Abciximab in a broad population of patients undergoing PCI (excluding patients with myocardial infarction and unstable angina meeting the EPIC high risk criteria) (10). Study procedures emphasized discontinuation of heparin after the procedure with early femoral arterial sheath removal and careful access site management (see PRECAUTIONS). EPILOG was a three-arm trial comparing Abciximab plus standard-dose heparin, Abciximab plus low-dose heparin, and placebo plus standard-dose heparin. Abciximab and heparin infusions were weight-adjusted in all arms. The Abciximab bolus plus infusion regimen was: 0.25 mg/kg bolus followed by a 0.125 μg/kg/min infusion (to a maximum of 10 μg/min) for 12 hours. The heparin regimen was either a standard-dose regimen (initial 100 U/kg bolus, target ACT ≥ 300 seconds) or a low-dose regimen (initial 70 U/kg bolus, target ACT ≥ 200 seconds).

The primary endpoint of the EPILOG trial was the composite of death or MI occurring within 30 days of PCI. The composite of death, MI, or urgent intervention was an important secondary endpoint. The endpoint events in the Abciximab treatment group were reduced mostly in the first 48 hours and this benefit was sustained through 30 days and six months (10) and one year (11). The (Kaplan-Meier) endpoint event rates at 30 days are shown in Table 1.

At the six-month follow up visit, the event rate for death, MI, or repeat (urgent or non-urgent) intervention remained lower in the Abciximab treatment arms (22.3% and 22.8%, respectively, for the standard- and low-dose heparin arms) than in the placebo arm (25.8%) and the event rate for death, MI, or urgent intervention was substantially lower in the Abciximab treatment arms (8.3% and 8.4%, respectively, for the standard- and low-dose heparin arms) than in the placebo arm (14.7%). The treatment associated effects continued to persist at the one-year follow up visit. The proportionate reductions in endpoint event rates were similar irrespective of the type of coronary intervention used (balloon angioplasty, atherectomy, or stent placement). Risk assessment using the American College of Cardiology/American Heart Association clinical/morphological criteria had large inter-observer variability. Consequently, a low risk subgroup could not be reproducibly identified in which to evaluate efficacy.

The EPISTENT trial was a randomized, multicenter trial evaluating three different treatment strategies in patients undergoing PCI: conventional PTCA with Abciximab plus low-dose heparin, primary intracoronary stent implantation with Abciximab plus low-dose heparin, and primary intracoronary stent implantation with placebo plus standard-dose heparin (12). The heparin dose was weight-adjusted in all arms. The JJIS Palmaz-Schatz stent was used in over 90% of the patients receiving stents. The two stent arms were blinded with respect to study agent (Abciximab or placebo) and heparin dose; the PCI arm with Abciximab was open-label. The Abciximab bolus plus infusion regimen was the same as that used in the EPILOG trial. The standard-dose and low-dose heparin regimens were the same as those used in the EPILOG trial. All patients were to receive aspirin; ticlopidine, if given, was to be started prior to study agent. Patient and access site management guidelines were the same as those for EPILOG, including a strong recommendation for early sheath removal.

The results demonstrated benefit in both Abciximab arms (i.e., with and without stents) compared with stenting alone on the composite of death, MI, or urgent intervention (repeat PCI or CABG) within 30 days of PCI (12). The (Kaplan-Meier) endpoint event rates at 30 days are shown in Table 2.

This benefit was maintained at 6 months: 12.1% of patients in the placebo/stent group experienced death, MI, or urgent revascularization compared with 6.4% of patients in the Abciximab/stent group (p<0.001 vs placebo/stent) and 9.2% in the Abciximab/PTCA group (p=0.051 vs placebo/stent). At 6 months, a reduction in the composite of death, MI, or all repeat (urgent or non-urgent) intervention was observed in the Abciximab/stent group compared with the placebo/stent group (15.4% vs 20.4%, p=0.006); the rate of this composite endpoint was similar in the Abciximab/PTCA and placebo/stent groups (22.4% vs 20.4%, p=0.467). (13)

CAPTURE was a randomized, double-blind, multicenter, placebo-controlled trial of the use of Abciximab in unstable angina patients not responding to conventional medical therapy for whom PCI was planned, but not immediately performed (14). The CAPTURE trial involved the administration of placebo or Abciximab starting 18 to 24 hours prior to PCI and continuing until one hour after completion of the intervention.

Patients were assessed as having unstable angina not responding to conventional medical therapy if they had at least one episode of myocardial ischemia despite bed rest and at least two hours of therapy with intravenous heparin and oral or intravenous nitrates. These patients were enrolled into the CAPTURE trial, if during a screening angiogram, they were determined to have a coronary lesion amenable to PCI. Patients received a bolus dose and intravenous infusion of placebo or Abciximab for 18 to 24 hours. At the end of the infusion period, the intervention was performed. The Abciximab or placebo infusion was discontinued one hour following the intervention. Patients were treated with intravenous heparin and oral or intravenous nitrates throughout the 18- to 24-hour Abciximab infusion period prior to the PCI.

The Abciximab dose was a 0.25 mg/kg bolus followed by a continuous infusion at a rate of 10 μg/min. The CAPTURE trial incorporated weight adjustment of the standard heparin dose only during the performance of the intervention, but did not investigate the effect of a lower heparin dose, and arterial sheaths were left in place for approximately 40 hours. The primary endpoint of the CAPTURE trial was the occurrence of any of the following events within 30 days of PCI: death, MI, or urgent intervention. The 30-day (Kaplan-Meier) primary endpoint event rates are shown in Table 3.

The 30-day results are consistent with the results of the other three trials, with the greatest effects on the myocardial infarction and urgent intervention components of the composite endpoint. As secondary endpoints, the components of the composite endpoint were analyzed separately for the period prior to the PCI and the period from the beginning of the intervention through Day 30. The greatest difference in MI occurred in the post-intervention period: the rates of MI were lower in the Abciximab group compared with placebo (Abciximab 3.6%, placebo 6.1%). There was also a reduction in MI occurring prior to the PCI (Abciximab 0.6%, placebo 2.0%). An Abciximab-associated reduction in the incidence of urgent intervention occurred in the post-intervention period. No effect on mortality was observed in either period. At six months of follow up, the composite endpoint of death, MI, or all repeat intervention (urgent or non-urgent) was not different between the Abciximab and placebo groups (Abciximab 31.0%, placebo 30.8%, p=0.77).

Mortality was uncommon in all four trials. Similar mortality rates were observed in all arms within each trial. Patient follow-up through one year of the EPISTENT trial suggested decreased mortality among patients treated with Abciximab and stent placement compared to patients treated with stent alone (8/794 vs. 19/809, p=0.037). Data from earlier studies with balloon angioplasty were not suggestive of the same benefit. In all four trials, the rates of acute MI were significantly lower in the groups treated with Abciximab. Most of the Abciximab treatment effect was seen in reduction in the rate of acute non-Q-wave MI. Urgent intervention rates were also lower in Abciximab-treated groups in these trials.

Anticoagulation

EPILOG and EPISTENT

Weight-adjusted low dose heparin, weight-adjusted Abciximab, careful vascular access site management and discontinuation of heparin after the procedure with early femoral arterial sheath removal were used.

The initial heparin bolus was based upon the results of the baseline ACT, according to the following regimen:

ACT < 150 seconds: administer 70 U/kg heparin

ACT 150 - 199 seconds: administer 50 U/kg heparin

ACT ≥ 200 seconds: administer no heparin

Additional 20 U/kg heparin boluses were given to achieve and maintain an ACT of ≥ 200 seconds during the procedure.

Discontinuation of heparin immediately after the procedure and removal of the arterial sheath within six hours were strongly recommended in the trials. If prolonged heparin therapy or delayed sheath removal was clinically indicated, heparin was adjusted to keep the APTT at a target of 60 to 85 seconds (EPILOG) or 55 to 75 seconds (EPISTENT).

CAPTURE trial

Anticoagulation was initiated prior to the administration of Abciximab. Anticoagulation was initiated with an intravenous heparin infusion to achieve a target APTT of 60 to 85 seconds. The heparin infusion was not uniformly weight adjusted in this trial. The heparin infusion was maintained during the Abciximab infusion and was adjusted to achieve an ACT of 300 seconds or an APTT of 70 seconds during the PCI. Following the intervention, heparin management was as outlined above for the EPILOG trial.

References

Adapted from the FDA Package Insert.