Efficacy and safety of alirocumab in high cardiovascular risk patients with inadequately controlled hypercholesterolaemia on maximally tolerated doses of statins: the ODYSSEY COMBO II randomized controlled trial

Hypercholesterolemia, low density lipoprotein receptor and proprotein convertase subtilisin/kexin-type 9

Atherosclerotic cardiovascular disease is the main cause of mortality and morbidity in the world. Plasma levels of low density lipoprotein cholesterol (LDL-C) are positively correlated with the risk of atherosclerosis. High plasma LDL concentrations in patients with hypercholesterolemia lead to build-up of LDL in the inner walls of the arteries, which becomes oxidized and promotes the formation of foam cells, consequently initiating atherosclerosis. Plasma LDL is mainly cleared through the LDL receptor (LDLR) pathway. Mutations in the LDLR cause familiar hypercholesterolemia and increase the risk of premature coronary heart disease. The expression of LDLR is regulated at the transcriptional level via the sterol regulatory element binding protein 2 (SREBP-2) and at the posttranslational levels mainly through proprotein convertase subtilisin/kexin-type 9 (PCSK9) and inducible degrader of the LDLR (IDOL). In this review, we summarize the latest advances in the studies of PCSK9.

Safety and efficacy of anti-PCSK9 antibodies: a meta-analysis of 25 randomized, controlled trials

BACKGROUND

Inhibition of proprotein convertase subtilisin/kexin type 9 (PCSK9) has been intensively studied to lower low-density lipoprotein cholesterol (LDL-C) levels. The purpose of this meta-analysis was to evaluate the safety and efficacy of anti-PCSK9 antibodies in randomized, controlled trials (RCTs).

METHODS

PubMed, EMBASE, CENTRAL databases, and recent conferences were searched. Safety outcomes were rates of common adverse events. Efficacy outcomes included percentages of LDL-C lowering and other lipid changes compared with placebo and ezetimibe, respectively.

RESULTS

Twenty-five RCTs encompassing 12,200 patients were included. The rates of common adverse events were firstly reported in our study by pooling together all evidence in RCTs, showing largely no significant difference between anti-PCSK9 antibodies and placebo (or ezetimibe), except that alirocumab was associated with reduced rates of death (relative risk (RR): 0.43, 95 % confidence interval (CI): 0.19 to 0.96, P = 0.04) and an increased rate of injection-site reactions (RR: 1.48, 95 % CI: 1.05 to 2.09, P = 0.02); evolocumab reduced the rate of abnormal liver function (RR: 0.43, 95 % CI: 0.20 to 0.93, P = 0.03), both compared with placebo. No significant difference in safety outcomes was detected between monthly 420 mg and biweekly 140 mg evolocumab treatments. Monthly 420 mg evolocumab treatment significantly reduced LDL-C by -54.6 % (95 % CI: -58.7 to -50.5 %) and by absolute -78.9 mg/dl (95 % CI: -88.9 to -68.9 mg/dl) versus placebo, and by -36.3 % (95 % CI: -38.8 to -33.9 %) versus ezetimibe, and increased high-density lipoprotein cholesterol (HDL-C) by 7.6 % (95 % CI: 5.7 to 9.5 %) versus placebo and 6.4 % (95 % CI: 4.3 to 8.4 %) versus ezetimibe. An equal or even greater change was observed following biweekly 140 mg administration. Significant and favorable changes were also detected in other lipids following evolocumab treatment. Biweekly 50 to 150 mg alirocumab lowered LDL-C by -52.6 % (95 % CI: -58.2 to -47.0 %) versus placebo, by -29.9 % (95 % CI: -32.9 to -26.9 %) versus ezetimibe, and increased HDL-C by 8.0 % (95 % CI: 4.2 to 11.7 %) versus placebo.

CONCLUSIONS

Evolocumab and alirocumab were safe and well-tolerated from our most-powered analyses. Both antibodies substantially reduced the LDL-C level by over 50 %, increased the HDL-C level, and resulted in favorable changes in other lipids.

Efficiency and safety of proprotein convertase subtilisin/kexin 9 monoclonal antibody on hypercholesterolemia: a meta-analysis of 20 randomized controlled trials

Background

Proprotein convertase subtilisin/kexin9 (PCSK9) monoclonal antibody significantly reduces low-density lipoprotein cholesterol level in patients with hypercholesterolemia. The goal of this study was to review recently reported randomized controlled trials to investigate the therapeutic effects and safety of PCSK9 inhibitors.

Methods and Results

The clinical randomized controlled trials published from inception to March 19, 2015 were identified from The Cochrane Library databases, PUBMED, and EBASE. Randomized controlled trials of at least 8 weeks duration using PCSK9 inhibitors in treating patients with hypercholesterolemia were included. Mean difference (MD) with a 95% CI was used to calculate the continuous data, the standardized mean difference with a 95% CI was used when the unit was not unified, and risk ratio with a 95% CI was used for dichotomous data. After screening, 20 trials fulfilled the inclusion criteria. PCSK9 inhibitors significantly decreased the levels of low-density lipoprotein cholesterol (MD=−65.29 mg/dL, 95% CI: −72.08 to −58.49), total cholesterol (MD=−60.04 mg/dL, 95% CI: −69.95 to −50.13), triglycerides (MD=−12.21 mg/dL, 95% CI: −16.21 to −8.22) and apolipoprotein-B (MD=−41.01 mg/dL, 95% CI: −46.07 to −35.94), lipoprotein(a) (standardized mean difference=−0.94, 95% CI: −1.12 to −0.77) and increased the levels of high-density lipoprotein cholesterol (MD=3.40 mg/dL, 95% CI: 3.12 to 3.68) and apolipoprotein-A1 (MD=6.75 mg/dL, 95% CI: 4.64 to 8.86). There was no significant difference in the incidence of treatment-emergent adverse events (risk ratio=1.01, 95% CI: 0.98 to 1.04), serious treatment-emergent adverse events (risk ratio=1.01, 95% CI: 0.88 to 1.17), and the discontinuation of treatment between the 2 groups (risk ratio=1.07, 95% CI: 0.86 to 1.34).

Conclusions

The meta-analysis indicated that PCSK9 inhibitors had a strong effect in lowering low-density lipoprotein cholesterol and other lipid levels with satisfactory safety and tolerability in patients with hypercholesterolemia.

Profile of evolocumab and its potential in the treatment of hyperlipidemia

Despite the proven efficacy of statins, they often fail to achieve low-density lipoprotein (LDL) cholesterol goals, especially in high-risk patients. Moreover, a large number of subjects cannot tolerate statins or full doses of these drugs, in particular patients with familial hypercholesterolemia. Thus, there is a need for additional effective LDL cholesterol-reducing agents. Evolocumab (AMG145) is a monoclonal antibody inhibiting proprotein convertase subtilisin/kexin type 9 that binds to the liver LDL receptor and prevents it from normal recycling by targeting it for degradation. Phase I, II, and III trials revealed that, on subcutaneous injection, either alone or in combination with statins, evolocumab is able to reduce high LDL cholesterol levels from 54% to 80%, apolipoprotein B100 from 31% to 61%, and lipoprotein(a) from 12% to 36%, in a dose-dependent manner. The incidence of side effects seems to be low and mainly limited to nasopharyngitis, injection site pain, arthralgia, and back pain. Evolocumab is an innovative powerful lipid-lowering drug, additive to statins and/or ezetimibe, with a large therapeutic range associated with a low rate of mild adverse events. If the available data are confirmed in long-term trials with strong outcome measures, evolocumab will become an essential tool in the treatment of a large number of high-risk patients, such as those affected by familial hypercholesterolemia, those who are unable to tolerate an efficacious statin dosage, and those at very high cardiovascular risk and unable to achieve their target LDL cholesterol levels with currently available lipid-lowering therapies.

PCSK9 (Proprotein convertase subtilisin/kexin type 9) inhibitors: past, present, and the future

Reduction in low-density lipoprotein cholesterol (LDL-C), mainly with statins, has decreased the risk of cardiovascular events over the last few decades. However, there are several patient populations that warrant further decrease in LDL-C by additional cholesterol-lowering therapy other than statins. Proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors are a new class of drugs that have been shown to further decrease LDL-C by 50-70% when administered as a monotherapy or on a background therapy with statins. Proprotein convertase subtilisin/kexin type 9 inhibitors are also an excellent example of drug development in which discovery of gene mutations and its clinical effects have rapidly progressed into successful preclinical and clinical studies with multiple Phases 1-3 clinical trials completed or ongoing to date. This review summarizes the rapid evolution of the drug from genetic discovery to identification of targets for the drugs, to animal and human testing, and to large clinical outcomes trials, followed by discussion on foreseeable challenges of PCSK9 inhibitors.

Targeting PCSK9 for therapeutic gains

Even though it is only a little over a decade from the discovery of proprotein convertase subtilisin/kexin type 9 (PCSK9) as a plasma protein that associates with both hypercholesterolemia and low cholesterol syndromes, a rich literature has developed describing its unique physiology and the impact of antagonism of this molecule on cholesterol metabolism for therapeutic purposes. Indeed, the PCSK9 story is unfolding rapidly, with many answers and more questions. This review summarizes the most recent data from phase II/III clinical trials of PCSK9 inhibition with the three leading antibodies, highlights the clinical significance of the ongoing studies, and suggests future areas of investigation based on recent basic science discoveries on the physiology of PCSK9.