Evaluation of Cardiovascular Outcomes After an Acute Coronary Syndrome During Treatment With Alirocumab - ODYSSEY OUTCOMES
Contribution To Literature:
The ODYSSEY OUTCOMES trial showed that use of alirocumab, taken every other week, significantly reduces ischemic events, including all-cause mortality and MI, compared with placebo among patients with an ACS event within the preceding 1-12 months.
The goal of the trial was to compare the safety and efficacy of alirocumab compared with placebo among patients with recent acute coronary syndrome (ACS) already on intensive or maximum-tolerated statin therapy.
Patients who were 1-12 months out from an ACS event were randomized, after a run-in phase of 2-16 weeks on high-intensity statin therapy, to alirocumab q2 weeks (n = 9,462 subcutaneously or placebo (n = 9,462). Drug was titrated between 75 and 150 mg to keep the low-density lipoprotein cholesterol (LDL-C) between 25 and 50 mg/dl, but above 15 mg/dl.
- Total number of enrollees: 18,924
- Duration of follow-up: 48 months
- Mean patient age: 58 years
- Percentage female: 25%
- Age ≥40 years
- 1-12 months prior to randomization
- Acute myocardial infarction (MI) or unstable angina
- High-intensity statin therapy (or documented intolerance to statins)
- Atorvastatin 40-80 mg daily, or
- Rosuvastatin 20-40 mg daily, or
- Maximum tolerated dose of one of these agents for ≥2 weeks
- Inadequate control of lipids
- LDL-C ≥70 mg/dl (1.8 mmol/L), or
- Non-HDL-C ≥100 mg/dl (2.6 mmol/L), or
- Apolipoprotein B ≥80 mg/dl
- Uncontrolled hypertension
- New York Heart Association class III or IV heart failure; left ventricular ejection fraction <25% if measured
- History of hemorrhagic stroke
- Fasting triglycerides >400 mg/dl (4.52 mmol/L)
- Use of fibrates other than fenofibrate or fenofibric acid
- Recurrent ACS within 2 weeks prior to randomization visit
- Coronary revascularization performed within 2 weeks prior to randomization visit, or planned after randomization
- Liver transaminases >3 x upper limit of normal (ULN); hepatitis B or C infection
- Creatine kinase (CK) >3 x ULN
- Estimated glomerular filtration rate <30 ml/min/1.73 m2
- Positive pregnancy test
Other salient features/characteristics:
- Diabetes mellitus: 29%
- Prior MI: 19%
- Time from ACS to randomization: 2.6 months (median)
- ACS type: non-ST-segment elevation MI (NSTEMI): 49%, STEMI: 35%
- Revascularization for index ACS: 72%
- Baseline LDL-C: 87 mg/dl, HDL-C: 43 mg/dl, triglycerides: 129 mg/dl
- High-dose atorvastatin/rosuvastatin: 89%; ezetimibe: 3%
The primary outcome, major adverse cardiac events (MACE), for alirocumab vs. placebo, was 9.5% vs. 11.1%, hazard ratio (HR) 0.85, 95% confidence interval 0.78-0.93, p = 0.0003.
- Coronary heart disease (CHD) death: 2.2% vs. 2.3%, p = 0.38
- MI: 6.6% vs. 7.6%, p = 0.006
- Ischemic stroke: 1.2% vs. 1.6%, p = 0.01
- Unstable angina: 0.4% vs. 0.6%, p = 0.02
Secondary outcomes (for alirocumab vs. placebo):
- Death/MI/ischemic stroke: 10.3% vs. 11.9%, p = 0.0003
- All-cause mortality: 3.5% vs. 4.1%, p = 0.026
- Ischemia-driven coronary revascularization: 7.7% vs. 8.8%, p = 0.009
- ALT >3 x ULN: 2.3% vs. 2.4%
- CK >10 x ULN: 0.5% vs. 0.5%
- Neutralizing antidrug antibodies: 42 vs. 6
- New-onset diabetes: 9.6% vs. 10.1%
On-treatment analysis, LDL-C reduction in alirocumab vs. placebo at 4 months (37.6 mg/dl vs. 93.3 mg/dl, 62.7% reduction), at 48 months (53.3 vs. 101.4 mg/dl, 54.7% reduction).
Patients with baseline LDL-C ≥100 mg/dl appeared to derive the highest benefit: MACE: 11.5% vs. 14.9%, HR 0.76; CHD death: 2.5% vs. 3.4%, cardiovascular death: 2.9% vs.4.2%, all-cause mortality: 4.1% vs. 5.7%, although the p-value for interaction based on baseline LDL-C levels was not significant.
The results of this landmark trial indicate that the use of alirocumab, taken every other week, significantly reduces ischemic events, including all-cause mortality and MI, among patients with an ACS event within the preceding 1-12 months. Nearly 90% of these patients were on a high dose of a potent statin (atorvastatin or rosuvastatin). Of note, the target LDL-C in this trial was 25-50 mg/dl, and the dose was adjusted to keep the LDL-C above 15 mg/dl. LDL-C reductions of >50% were observed early, and appeared more or less sustained during follow-up.
A few points to consider: This trial differs from the other PCSK9 inhibitor outcomes trial (FOURIER – evolocumab) in the patient population enrolled – post-ACS vs. stable established atherosclerotic disease. Differences in mortality noted in this trial were not noted in FOURIER, possibly due to the higher risk patient population enrolled in ODYSSEY OUTCOMES; reductions in LDL-C seemed qualitatively similar. Secondly, this trial further reinforces the “lower is better” hypothesis with LDL-C, and will likely once again reopen the debate about treating patients based on lipid levels rather than intensity of statin therapy alone. Interestingly, the CTT meta-analysis suggests an approximate 22% reduction in CHD events with every 1 mmol/L (38 mg/dl) reduction in LDL-C; the benefits noted in this trial seem somewhat attenuated compared with this maxim. Next, there was a slight attenuation of reduction in LDL-C over long-term follow-up in this trial. This trend upward in the LDL is thought to be due to the study design of reducing treatment dose in the face of very low LDL levels and not due to a significant presence of neutralizing antibodies. The SPIRE trial program with bococizumab had to be abandoned due to this issue of neutralizing antibodies.
Finally, PCSK9 inhibitors are very expensive medications; cost-effectiveness analyses will be important going forward. Based on the subgroup analysis based on LDL-C levels, the cost-benefit ratio is likely to be most favorable in this patient population.
Presented by Dr. Philippe Steg at the American College of Cardiology Annual Scientific Session (ACC 2018), Orlando, FL, March 10, 2018.
Clinical Topics: Acute Coronary Syndromes, Cardiac Surgery, Diabetes and Cardiometabolic Disease, Dyslipidemia, Invasive Cardiovascular Angiography and Intervention, Prevention, Cardiac Surgery and Arrhythmias, Lipid Metabolism, Nonstatins, Novel Agents, Statins, Interventions and ACS
Keywords: ACC18, ACC Annual Scientific Session, Acute Coronary Syndrome, Antibodies, Monoclonal, Angina, Unstable, Apolipoproteins B, Brain Ischemia, Cholesterol, HDL, Cholesterol, LDL, Coronary Disease, Cost-Benefit Analysis, Diabetes Mellitus, Dyslipidemias, Hydroxymethylglutaryl-CoA Reductase Inhibitors, Lipids, Myocardial Infarction, Myocardial Revascularization, Secondary Prevention, Stroke, Treatment Outcome
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