Functional Analysis of LDLR (Low-Density Lipoprotein Receptor) Variants in Patient Lymphocytes to Assess the Effect of Evinacumab in Homozygous Familial Hypercholesterolemia Patients With a Spectrum of LDLR Activity

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Abstract

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Objective:

Homozygous familial hypercholesterolemia is a rare disease usually caused by LDLR (low-density lipoprotein receptor) mutations. Homozygous familial hypercholesterolemia is characterized by markedly elevated LDL-C (low-density lipoprotein cholesterol) levels and an extremely high risk of premature atherosclerotic cardiovascular disease. A phase 2, proof-of-concept study (NCT02265952) demonstrated that evinacumab, a fully human monoclonal antibody to ANGPTL3 (angiopoietin-like 3 protein), reduced LDL-C levels in 9 patients with genotypically confirmed homozygous familial hypercholesterolemia and was well tolerated. The aim of this study was to analyze the effects of evinacumab on LDLR activity in lymphocytes purified from patients in the proof-of-concept study.

Approach and Results:

LDLR activity was assessed in patient lymphocytes before and after treatment with evinacumab and versus lymphocytes carrying wild-type LDLR, and also in an LDLR-defective Chinese hamster ovary cell line (CHO- ldlA7) transfected with plasmids encoding the LDLR variants. Overall mean peak reduction in LDL-C with evinacumab was −58±18%, occurring between Week 4 and Week 12. Mutations identified in the 9 patients were shown to be pathogenic, with loss of LDLR activity versus wild type. Two of the LDLR variants, p.(Cys681*) and p.(Ala627Profs*38), were class 2 type mutations that are retained in the endoplasmic reticulum. Six variants were class 3 type mutations with impaired LDL-C binding activity: p.(Trp87Gly), occurring in 2 patients, p.(Gln254Pro), p.(Ser177Leu), p.(Gly335Val), and p.(Ser306Leu). Evinacumab had no effect on LDLR activity.

Conclusions:

These results suggest that evinacumab is effective for lowering LDL-C in patients with homozygous familial hypercholesterolemia, and the inhibition of ANGPTL3 in humans lowers LDL-C in a mechanism independent of the LDLR.

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Most cited references 35

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Effect of a monoclonal antibody to PCSK9, REGN727/SAR236553, to reduce low-density lipoprotein cholesterol in patients with heterozygous familial hypercholesterolaemia on stable statin dose with or without ezetimibe therapy: a phase 2 randomised controlled trial.

Evan A Stein, Dan Gipe, Jean Bergeron … (2012)

Inhibition of proprotein convertase subtilisin/kexin type 9 serine protease (PCSK9) resulted in large reductions of low-density lipoprotein cholesterol (LDL-C) in phase 1 trials. We assessed the efficacy and safety of various doses and dosing intervals of REGN727, a monoclonal antibody to PCSK9, added to statins, to further lower LDL-C in patients with heterozygous familial hypercholesterolaemia. This multicentre, randomised, placebo-controlled phase 2 trial was done at 16 lipid clinics in the USA and Canada. Between Jan 18, 2011, and Nov 7, 2011, we enrolled adults with heterozygous familial hypercholesterolaemia and LDL-C concentrations of 2·6 mmol/L or higher on stable diet and statin dose, with or without ezetimibe. Patients were randomly assigned to receive REGN727 150 mg, 200 mg, or 300 mg every 4 weeks, or 150 mg every 2 weeks, or placebo every 2 weeks (ratio 1:1:1:1:1). Randomisation was stratified by concomitant use of ezetimibe at baseline. Investigators, study staff, and patients were masked to treatment group. Blinding was maintained by administration of placebo alternating with REGN727 for the groups of 4 week dosing. The primary endpoint was mean percent reduction in LDL-C from baseline at week 12 and was analysed in the modified intention-to-treat population with an analysis of covariance (ANCOVA) model with treatment group. This trial is registered in ClinicalTrials.gov, number NCT 01266876. 77 patients were randomly assigned to study groups (15-16 patients per group) and all were analysed. Least-squares (LS) mean LDL-C reduction from baseline to week 12 was 28·9% (SE 5·08) for 150 mg every 4 weeks (p=0·0113), 31·54% (4·91) for 200 mg every 4 weeks (p=0·0035), 42·53% (5·09) for 300 mg every 4 weeks (p<0·0001), and 67·90% (4·85) for 150 mg every 2 weeks (p<0·0001), compared with 10·65% (5·04) with placebo. One serious adverse event was reported with placebo and none with REGN727. No increases of more than three times the upper limit of normal were reported for hepatic transaminases or creatinine kinase. The most common adverse event was injection-site reaction with one patient in the group of 300 mg REGN727 terminating treatment. REGN727 was well tolerated and achieved substantial further LDL-C reduction in patients with heterozygous familial hypercholesterolaemia and elevated LDL-C treated with high-dose statins, with or without ezetimibe. REGN727 has the potential to provide optimum control of LDL-C in patients with this disorder. Sanofi US and Regeneron Pharmaceuticals Incorporated. Copyright © 2012 Elsevier Ltd. All rights reserved.

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Rare loss-of-function mutations in ANGPTL family members contribute to plasma triglyceride levels in humans.

Aileen C. Cohen, Stefano Romeo, Julia Kozlitina … (2008)

The relative activity of lipoprotein lipase (LPL) in different tissues controls the partitioning of lipoprotein-derived fatty acids between sites of fat storage (adipose tissue) and oxidation (heart and skeletal muscle). Here we used a reverse genetic strategy to test the hypothesis that 4 angiopoietin-like proteins (ANGPTL3, -4, -5, and -6) play key roles in triglyceride (TG) metabolism in humans. We re-sequenced the coding regions of the genes encoding these proteins and identified multiple rare nonsynonymous (NS) sequence variations that were associated with low plasma TG levels but not with other metabolic phenotypes. Functional studies revealed that all mutant alleles of ANGPTL3 and ANGPTL4 that were associated with low plasma TG levels interfered either with the synthesis or secretion of the protein or with the ability of the ANGPTL protein to inhibit LPL. A total of 1% of the Dallas Heart Study population and 4% of those participants with a plasma TG in the lowest quartile had a rare loss-of-function mutation in ANGPTL3, ANGPTL4, or ANGPTL5. Thus, ANGPTL3, ANGPTL4, and ANGPTL5, but not ANGPTL6, play nonredundant roles in TG metabolism, and multiple alleles at these loci cumulatively contribute to variability in plasma TG levels in humans.

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ANGPTL3 Inhibition in Homozygous Familial Hypercholesterolemia

William Sasiela, Kuo-Chen Chan, Diane Brisson … (2017)

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Author and article information

Journal

Journal ID (nlm-ta): Arterioscler Thromb Vasc Biol

Journal ID (iso-abbrev): Arterioscler. Thromb. Vasc. Biol

Journal ID (publisher-id): ATV

Title: Arteriosclerosis, Thrombosis, and Vascular Biology

Publisher: Lippincott Williams & Wilkins

ISSN (Print): 1079-5642

ISSN (Electronic): 1524-4636

Publication date (Print): November 2019

Publication date (Electronic): 03 October 2019

Volume: 39

Issue: 11

Pages: 2248-2260

Affiliations

[1 ]From Regeneron Pharmaceuticals, Inc, Tarrytown, NY (P.B., K-C.C., M.T., P.J.S., R.P., D.A.G.)

[2 ]Biofisika Institute (UPV/EHU, CSIC) and Department of Biochemistry and Molecular Biology, UPV/EHU, Spain (A.B-V., K.B.U, C.M.)

[3 ]Unidade de I&D, Grupo de Investigação Cardiovascular, Departamento de Promoção da Saúde e Prevenção de Doenças Não Transmissíveis, Instituto Nacional de Saúde Doutor Ricardo Jorge, Lisboa, Portugal (A.C.A., M.B.)

[4 ]BioISI - Biosystems & Integrative Sciences Institute, Faculdade de Ciências, Universidade de Lisboa, Portugal (A.C.A., M.B.)

[5 ]Clinical Lipidology and Rare Lipid Disorders Unit, Department of Medicine, Université de Montréal Community Gene Medicine Center, Lipid Clinic Chicoutimi Hospital and ECOGENE-21 Clinical and Translational Research Center, Chicoutimi, Quebec, Canada (D.G.).

Author notes

Correspondence to: Cesar Martin, PhD, Biofisika Institute (UPV/EHU, CSIC), Barrio Sarriena, 48940 Leioa Bizkaia, Spain. Email cesar.martin@ 123456ehu.eus

Article

Accession ID: 00010

DOI: 10.1161/ATVBAHA.119.313051

PMC ID: 6818983

PubMed ID: 31578082

SO-VID: e963dd2c-5ad6-44a6-882a-c798f02d213d

License:

Arteriosclerosis, Thrombosis, and Vascular Biology is published on behalf of the American Heart Association, Inc., by Wolters Kluwer Health, Inc. This is an open access article under the terms of the Creative Commons Attribution Non-Commercial-NoDerivs License, which permits use, distribution, and reproduction in any medium, provided that the original work is properly cited, the use is noncommercial, and no modifications or adaptations are made.

History

Date received : 8 June 2019

Date accepted : 16 September 2019

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Keywords: hypercholesterolemia,lipoproteins,mutations,proof of concept study,rare disease

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Keywords: hypercholesterolemia, lipoproteins, mutations, proof of concept study, rare disease

Functional Analysis of LDLR (Low-Density Lipoprotein Receptor) Variants in Patient Lymphocytes to Assess the Effect of Evinacumab in Homozygous Familial Hypercholesterolemia Patients With a Spectrum of LDLR Activity

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Abstract

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Most cited references 35

Effect of a monoclonal antibody to PCSK9, REGN727/SAR236553, to reduce low-density lipoprotein cholesterol in patients with heterozygous familial hypercholesterolaemia on stable statin dose with or without ezetimibe therapy: a phase 2 randomised controlled trial.

Rare loss-of-function mutations in ANGPTL family members contribute to plasma triglyceride levels in humans.

ANGPTL3 Inhibition in Homozygous Familial Hypercholesterolemia

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