Effect of PCSK9 inhibition with evolocumab on lipoprotein subfractions in familial dysbetalipoproteinemia (type III hyperlipidemia)

Use of Apolipoprotein B in the Era of Precision Medicine: Time for a Paradigm Change?

Atherosclerotic cardiovascular disease (ASCVD) remains the leading cause of death worldwide and the risk of a major cardiovascular event is highest among those with established disease. Ongoing management of these patients relies on the accurate assessment of their response to any prescribed therapy, and their residual risk, in order to optimize treatment. Recent international guidelines and position statements concur that the plasma concentration of apolipoprotein B (apoB) is the most accurate measure of lipoprotein associated ASCVD risk. This is especially true for the growing number of individuals with diabetes, obesity, or the metabolic syndrome, and those on statin therapy. Most guidelines, however, continue to promote LDL-C as the primary risk marker due to uncertainty as to whether the greater accuracy of apoB is sufficient to warrant a paradigm shift. Recommendations regarding apoB measurement vary, and the information provided on how to interpret apoB results is sometimes insufficient, particularly for non-lipid specialists. Misinformation regarding the reliability of the assays is also frequently repeated despite its equivalent or better standardization than many other diagnostic assays. Thus, demand for apoB testing is relatively low, which means there is little incentive to increase its availability or reduce its cost. In this review, we examine the results of recent clinical outcomes studies and meta-analyses on the relative values of apoB, LDL-C, and non-HDL-C as markers of ASCVD risk. Although there is seemingly minimal difference among these markers when only population-based metrics are considered, it is evident from our analysis that, from a personalized or precision medicine standpoint, many individuals would benefit, at a negligible total cost, if apoB measurement were better integrated into the diagnosis and treatment of ASCVD.

Imine Derivatives of Benzoxazole Attenuate High-Fat Diet-Induced Hyperlipidemia by Modulation of Lipid-Regulating Genes

Purpose: Hyperlipidemia being the prominent risk factor of cardiovascular diseases and side effects associated with the current lipid-lowering drugs have attracted the interest of scientists in the quest for new alternatives. In view of the diverse pharmacological potentials of benzoxazole (BZX) compounds, this study was designed to evaluate the antihyperlipidemic activity of imine derivatives of BZX in high-fat diet (HFD)-fed rats. Methods: Hyperlipidemia was induced in Sprague-Dawley rats by using HFD for 28 days. On the 28th day, blood samples were collected, and animals having serum triglycerides (TG) greater than 400 mg/dL and total cholesterol (TC) greater than 280 mg/dL were selected for further study. Hyperlipidemic rats were daily treated with either a vehicle or simvastatin (SIM; 20 mg/kg) or BZX compounds (10, 20, and 30 mg/kg), for 12 consecutive days. After the specified time duration, hyperlipidemic biomarkers were evaluated in the blood samples of sacrificed rats. Liver samples were collected for histopathological and mRNA analyses. Binding affinities of BZX derivatives with different targets were assessed by molecular docking. Results: The present study revealed that the BZX derivatives dose-dependently reduced the serum levels of TC, TG, low-density lipoprotein, and very low-density lipoprotein along with improvement in high-density lipoprotein levels. Similarly, all the compounds reduced HFD-induced alanine transaminase and aspartate aminotransferase levels except BZX-4. Histopathology of liver samples demonstrated mild to moderate fatty changes upon treatment with BZX-1, BZX-2, and BZX-4. The hepatic architecture of the BZX-3-treated samples was close to normal, and only mild inflammation was witnessed in these samples. Moreover, all the compounds significantly increased superoxide dismutase and glutathione levels, indicating their antioxidant potentials. Gene expression data showed that BZX-1 and BZX-3 reduced lipid levels by inhibiting HMGCR, APOB, PCSK9, SRB1, and VCAM1 and via improving PPAR-α and APOE mRNA levels. BZX-2 demonstrated its antihyperlipidemic effects mainly due to inhibition of APOB, while BZX-4-mediated effects appeared to be due to attenuation of APOB, PCSK9, and SRB1. BZX derivatives displayed strong binding affinities with HMGCR, APOB, and VCAM1, which suggested that some of the interactions might be required for inhibition of these target proteins. Conclusions: Based on the current findings, it can be concluded that BZX derivatives exert their antihyperlipidemic effects via modulation of multiple lipid-regulating genes.

A Translational Tool to Facilitate Use of Apolipoprotein B for Clinical Decision-Making

BACKGROUND

Despite recent large-scale discordance studies showing definitively that atherosclerotic cardiovascular disease (ASCVD) risk correlates better with apolipoprotein B (apoB) than with low-density lipoprotein cholesterol (LDL-C), the latter remains the recommended metric for guiding lipid-lowering treatment decisions in the United States. A major barrier to change, in this regard, is the lack of guideline-recommended apoB treatment targets. We developed a simple method to "translate" apoB values into population-equivalent LDL-C units, allowing apoB-based treatment decisions to be made using LDL-C targets.

METHODS

Sequentially collected, population-based samples underwent standard lipid panel analysis and apoB testing by immunoassay. Those with triglycerides greater than 1000 mg/dl were excluded, leaving a study cohort of 15 153 individuals.

RESULTS

Linear regression of calculated LDL-C values against percentile-equivalent apoB values yielded an equation to convert apoB into percentile-equivalent LDL-C units: [LDL-C equivalents = 1.38(apoB) - 29] (R2 = 0.999). The extent of discordance between LDL-C and apoB was examined in subgroups with similar LDL-C, ranging from very low (55-70 mg/dL) to very high (175-190 mg/dL). Among individuals with very low LDL-C, 40% had discordantly higher apoB, indicating higher ASCVD risk. Of those with very high LDL-C, 49% had discordantly lower apoB. Across the range, a minority of patients (25%-40%) had concordant levels of apoB, confirming that discordance between these biomarkers is highly prevalent. Similar results were found in discordance analysis between apoB and non-high-density lipoprotein cholesterol (HDL-C).

CONCLUSIONS

Providing visibility to discrepancies among LDL-C, non-HDL-C, and apoB should help to facilitate more rapid and widespread adoption of apoB for managing ASCVD risk.

Effect of evolocumab on fasting and post fat load lipids and lipoproteins in familial dysbetalipoproteinemia

BACKGROUND

Familial dysbetalipoproteinemia (FD) is the second most common monogenic lipid disorder (prevalence 1 in 850-3500), characterized by postprandial remnant accumulation and associated with increased cardiovascular disease (CVD) risk. Many FD patients do not achieve non-HDL-C treatment goals, indicating the need for additional lipid-lowering treatment options.

OBJECTIVES

To evaluate the effect of the PCSK9 monoclonal antibody evolocumab added to standard lipid-lowering therapy on fasting and post fat load lipids and lipoproteins in patients with FD.

METHODS

A randomized placebo-controlled double-blind crossover trial comparing evolocumab (140 mg subcutaneous every 2 weeks) with placebo during two 12-week treatment periods. At the start and end of each treatment period patients received an oral fat load. The primary endpoint was the 8-hour post fat load non-HDL-C area under the curve (AUC). Secondary endpoints included fasting and post fat load lipids and lipoproteins.

RESULTS

In total, 28 patients completed the study. Mean age was 62±9 years and 93% had an Ɛ2Ɛ2 genotype. Evolocumab reduced the 8-hour post fat load non-HDL-C AUC with 49% (95%CI 42-55) and apolipoprotein B (apoB) AUC with 47% (95%CI 41-53). Other fasting and absolute post fat load lipids and lipoproteins including triglycerides and remnant-cholesterol were also significantly reduced by evolocumab. However, evolocumab did not have significant effects on the rise above fasting levels that occurred after consumption of the oral fat load.

CONCLUSIONS

Evolocumab added to standard lipid-lowering therapy significantly reduced fasting and absolute post fat load concentrations of non-HDL-C, apoB and other atherogenic lipids and lipoproteins in FD patients. The clinically significant decrease in lipids and lipoproteins can be expected to translate into a reduction in CVD risk in these high-risk patients.

Dysbetalipoproteinemia Is Associated With Increased Risk of Coronary and Peripheral Vascular Disease

CONTEXT

Dysbetalipoproteinemia (DBL) is a disorder in which remnant lipoproteins accumulate in the plasma due to a genetic apolipoprotein E dysfunction in conjunction with the presence of secondary metabolic factors. An increased risk of both coronary and peripheral vascular disease (PVD) has been observed in these patients in retrospective studies.

OBJECTIVE

The primary objective was to compare the incidence of atherosclerotic cardiovascular disease (ASCVD) and PVD in a cohort of patients with DBL compared with normolipidemic controls. As a secondary objective, the incidence of ASCVD and PVD was compared between patients with DBL and patients with familial hypercholesterolemia (FH).

METHODS

A total of 221 patients with DBL, 725 patients with FH, and 1481 normolipidemic controls were included in the study. The data were obtained by review of medical records.

RESULTS

In patients with DBL, there was an overall excess risk of PVD (hazard ratio [HR] 13.58, 95% CI 4.76-38.75) and ASCVD (HR 3.55, 95% CI 2.17-5.83) (P < .0001) when compared with normolipidemic controls. When compared with patients with FH, an increased risk of PVD (HR 3.89, 95% CI 1.20-12.55, P = .02) was observed in patients with DBL.

CONCLUSION

We demonstrated that the risks of ASCVD and PVD in DBL are >3-fold and >13-fold higher, respectively, than normolipidemic controls. Furthermore, the risk of PVD is ∼4-fold higher in DBL than in FH. Adequate screening of DBL is imperative to improve the clinical care of these patients by preventing the development of ASCVD.

Effect of PCSK9 inhibitors on remnant cholesterol and lipid residual risk: The LIPID-REAL registry

BACKGROUND

Monoclonal antibodies that inhibit the proprotein convertase subtilisin/kexin type 9 (PCSK9) reduce low-density lipoprotein cholesterol (LDLc) by 55%, regardless of baseline treatments. Nonetheless, the effect of other lipid parameters, such as cholesterol remnants or, the so-called lipid residual risk, is unknown.

METHODS

Multicenter and retrospective registry of patients treated with PCSK9 inhibitors from 14 different hospitals in Spain. Before and on-treatment lipid parameters were recorded. Residual lipid risk was estimated by (1) cholesterol remnants, (2) triglycerides/HDLc ratio (TG/HDL), (3) total cholesterol/HDLc (TC/HDL) and (4) the triglycerides-to-glucose index (TGGi).

RESULTS

Six hundred fifty-two patients were analysed, mean age of 60.2 (9.63) years, 24.69% women and mean LDLc before treatment 149.24 (49.86) mg/dl. Median time to second blood determination was 187.5 days. On-treatment LDLc was 67.46 (45.78) mg/dl, which represented a 55% reduction. Significant reductions were observed for TG/HDL ratio, cholesterol remnants, TC/HDL ratio and TGGi. As consequence, 34.61% patients had LDLc <55 mg/dl and cholesterol remnants <30 mg/dl; additionally, 31.95% had cholesterol remnants <30 mg/dl but LDLc >55 mg/dl. Patients who had levels of cholesterol remnants >30 mg/dl before initiating the treatment with PCSK9 had higher reductions in cholesterol remnants, TG/HDL ratio, TC/HDL and TGGi. By contrast, no reduction differences were observed according to baseline LDLc (< or > the mean), age, gender or obesity.

CONCLUSIONS

This multicenter and retrospective registry of real-world patients treated with PCSK9 inhibitors demonstrates a positive effect on cholesterol remnants and lipid residual risk beyond LDLc reductions.

Effect of Early Initiation of Evolocumab on Lipoprotein(a) in Patients with Acute Myocardial Infarction: Sub-Analysis of a Randomized Controlled Trial

Elevated circulating lipoprotein(a) levels are associated with an increased risk of cardiovascular events. We reported that early initiation of evolocumab, a proprotein convertase subtilisin/kexin type 9 inhibitor, in addition to a statin substantially reduced the lipoprotein(a) levels in patients with acute myocardial infarction (AMI) after primary percutaneous coronary intervention (PCI). This sub-analysis sought to investigate the effect of evolocumab on lipoprotein(a) based on baseline lipoprotein(a) levels and characteristics. This study was a prespecified analysis of a randomized controlled trial that enrolled 102 patients who underwent primary PCI for AMI. Patients received pitavastatin (2 mg/day) alone or pitavastatin and evolocumab 140 mg subcutaneously within 24 h and 2 weeks after the index PCI. The evolocumab group showed significantly suppressed lipoprotein(a) levels in patients with baseline lipoprotein(a) levels of ≤10 mg/dL, 10 < lipoprotein(a) ≤ 20 mg/dL, and >20 mg/dL compared with the control group, as well as similar reductions in lipoprotein(a) levels in all patient subgroups. Among these subgroups, evolocumab tended to show more favorable effects in patients with diabetes mellitus. In AMI patients, early initiation of evolocumab therapy within 24 h of primary PCI suppressed the increase in lipoprotein(a) levels within 4 weeks, regardless of baseline levels and characteristics.