Search

Heterozygous familial hypercholesterolemia (HeFH) is characterized by a prevalence of 1/200 (higher than 1/500 as previously estimated): based on this updated prevalence, in Italy there are about 250-300 000 subjects with HeFH. Patients with HeFH are significantly underdiagnosed (in Italy only 4-5% of total estimated HeFH are properly diagnosed), undertreated (only 1 in 5 to 10 HeFH at target for LDL-cholesterol), and characterized by a high or very high cardiovascular risk. There are simple criteria for the diagnosis of familial hypercholesterolemia such as those issued by the Dutch Lipid Clinic Network (DLCN), easy to implement both in general practice as well as by the specialists. Genetic diagnosis is strongly suggested to support the diagnosis of familial hypercholesterolemia. Lipid-lowering therapy with high dose of highly effective statins, often associated with ezetimibe, should be initiated immediately at diagnosis in adults and at age 8-10 years in childhood. Evolocumab and alirocumab are monoclonal antibodies against PCSK9. They are a highly innovative lipid-lowering approach, characterized by a good safety profile and a remarkable LDL-cholesterol lowering effect when associated with the maximally tolerated dose of statins plus ezetimibe. Studies with alirocumab and evolocumab in HeFH patients show a further LDL-cholesterol decrease by 50-60% vs intensive lipid-lowering therapy with statins ± ezetimibe, with 70-80% of HeFH patients achieving their LDL-cholesterol targets.

Evolocumab (Repatha(®)) is a monoclonal antibody targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) that is administered subcutaneously at a dosage of 140 mg every 2 weeks or 420 mg once monthly. Across 12-week phase III trials in patients with primary hypercholesterolemia or mixed dyslipidemia, evolocumab was more effective than placebo (treatment difference -54.8 to -76.3%) and/or ezetimibe (treatment difference -36.9 to -47.2%) at reducing low-density lipoprotein cholesterol (LDL-C) levels, including when added to statin therapy, when administered to statin-intolerant patients, when administered as monotherapy, and in patients with heterozygous familial hypercholesterolemia who were receiving statins with or without other lipid-lowering drugs. Evolocumab also significantly lowered LDL-C levels (treatment difference of ≈30% vs. placebo) in patients with homozygous familial hypercholesterolemia when added to statins with or without ezetimibe in a 12-week phase III trial. The efficacy of evolocumab was maintained in the longer term, and it was well tolerated. In conclusion, subcutaneous evolocumab is a valuable new treatment for use in primary hypercholesterolemia or mixed dyslipidemia and homozygous familial hypercholesterolemia, particularly in patients unable to reach LDL-C goals despite treatment with statins with or without other lipid-lowering therapies and in patients who do not tolerate or are not able to receive statins.

Objective: To review the mechanism of action for PCSK9 monoclonal antibodies and critically evaluate the therapeutic potential of evolocumab and alirocumab in the treatment of hypercholesterolemia., Data Sources: Ovid MEDLINE search from 1980 to August 2015 using the terms PCSK9, evolocumab, and alirocumab with forward and backward citation tracking., Study Selection and Data Extraction: English-language trials and studies assessing the mechanism, efficacy, or safety of PCSK9 monoclonal antibodies were included., Data Synthesis: PCSK9 monoclonal antibodies have a potent ability to reduce low-density lipoprotein (LDL) by almost 50% in controlled trials: -47.49% (95% CI = -69.6% to -25.4%). They have an acceptable safety profile with no significant elevations in Creatine Kinase (CK) (odds ratio [OR] = 0.72; 95% CI = 0.54 to 0.96) or serious adverse events (OR = 1.01; 95% CI = 0.87 to 1.18), and preliminary evidence suggests reductions in myocardial infarction (OR = 0.49; 95% CI = 0.26 to 0.93). Although it is effective in several familial hypercholesterolemia (FH) patient types, it does not work in homozygous patients with dual allele LDL receptor negative polymorphisms or those who are homozygous for autosomal recessive hypercholesterolemia., Conclusions: Although not preferred over statins because of limited clinical trial evidence of cardiovascular event reductions, dosing convenience, and expense, PCSK9 monoclonal antibodies will have a prominent role to play in the treatment of hypercholesterolemia, especially in patients needing large LDL reductions, including patients with many types of FH., (© The Author(s) 2015.)

Monoclonal antibodies (mAbs) to proprotein convertase subtilisin/kexin type 9 (PCSK-9) can further lower LDL-C by ≥60% in statin-treated patients. Preliminary data suggest they may reduce cardiovascular (CVD) events. Ongoing PCSK-9 mAb cardiovascular outcomes trials could provide the opportunity to determine whether a "legacy effect" similar to that observed for statins will occur over the post-trial observation period. We hypothesize these trials could demonstrate that (1) very aggressive LDL-C lowering with PCSK-9 mAbs added to background statin therapy will induce extensive atherosclerosis stabilization and regression in the large majority of treated patients, and (2) continued maintenance therapy with high intensity statin therapy (with or without ezetimibe) should then inhibit new plaque formation, with a long-term prevention of CVD events. The necessity of expensive lifetime treatment with PCSK-9 inhibitors could then be avoided in all but a small subset of patients who could benefit from longer treatment., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

Lilly PCSK9 antibody LY3015014 (LY) is a monoclonal antibody (mAb) that neutralizes proprotein convertase subtilisin-kexin type 9 (PCSK9). LY decreases LDL cholesterol in monkeys and, unlike other PCSK9 mAbs, does not cause an accumulation of intact PCSK9 in serum. Comparing the epitope of LY with other clinically tested PCSK9 mAbs, it was noted that the LY epitope excludes the furin cleavage site in PCSK9, whereas other mAbs span this site. In vitro exposure of PCSK9 to furin resulted in degradation of PCSK9 bound to LY, whereas cleavage was blocked by other mAbs. These other mAbs caused a significant accumulation of serum PCSK9 and displayed a shorter duration of LDL-cholesterol lowering than LY when administered to mice expressing the WT human PCSK9. In mice expressing a noncleavable variant of human PCSK9, LY behaved like a cleavage-blocking mAb, in that it caused significant PCSK9 accumulation, its duration of LDL lowering was reduced, and its clearance (CL) from serum was accelerated. Thus, LY neutralizes PCSK9 and allows its proteolytic degradation to proceed, which limits PCSK9 accumulation, reduces the CL rate of LY, and extends its duration of action. PCSK9 mAbs with this property are likely to achieve longer durability and require lower doses than mAbs that cause antigen to accumulate., (Copyright © 2015 by the American Society for Biochemistry and Molecular Biology, Inc.)

Background: Guidelines recommend statins as first-line therapy for dyslipidemia. Monoclonal antibodies targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) is a new lipid-lowering approach., Purpose: To assess the efficacy and safety of PCSK9 antibodies in adults with hypercholesterolemia., Data Sources: MEDLINE, PubMed Central, and Google Scholar; conference proceedings; and the ClinicalTrials.gov registry through 4 April 2015., Study Selection: Phase 2 or 3 randomized, controlled trials (RCTs) comparing treatment using PCSK9 antibodies with no anti-PCSK9 therapy in adults with hypercholesterolemia., Data Extraction: Two investigators independently extracted data on study characteristics and lipid and clinical outcomes, and rated risk of bias of trials. Prespecified primary end points were all-cause and cardiovascular mortality., Data Synthesis: Twenty-four RCTs comprising 10 159 patients were included. Compared with no antibody, treatment with PCSK9 antibodies led to marked reductions in low-density lipoprotein cholesterol levels (mean difference, -47.49% [95% CI, -69.64% to -25.35%]; P < 0.001] and other atherogenic lipid fractions, and it reduced all-cause mortality (odds ratio [OR], 0.45 [CI, 0.23 to 0.86]; P = 0.015; heterogeneity P = 0.63; I2 = 0%) and cardiovascular mortality (OR, 0.50 [CI, 0.23 to 1.10]; P = 0.084; heterogeneity P = 0.78; I2 = 0%). The rate of myocardial infarction was significantly reduced with use of PCSK9 antibodies (OR, 0.49 [CI, 0.26 to 0.93]; P = 0.030; heterogeneity P = 0.45; I2 = 0%), and increases in the serum creatine kinase level were reduced (OR, 0.72 [CI, 0.54 to 0.96]; P = 0.026; heterogeneity P = 0.65; I2 = 0%). Serious adverse events did not increase with administration of PCSK9 antibodies., Limitation: Results were derived from study-level data rather than patient-level data, and clinical outcome data are rare., Conclusion: PCSK9 antibodies seem to be safe and effective for adults with dyslipidemia., Primary Funding Source: CRC 1116 Masterswitches in Myocardial Ischemia, German Research Council DFG.

Low-density lipoprotein cholesterol (LDL-C) reduction with statins is the cornerstone of atherosclerotic cardiovascular disease (CVD) prevention. The LDL-C lowering non-statin therapy ezetimibe also modestly reduces CVD risk when added to statin therapy. There remains a clinical need for additional LDL-C lowering agents to reduce CVD risk in patients with genetic hypercholesterolemia, statin intolerance, or who are at high risk due to clinical CVD or diabetes. In clinical trials, proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibition using monoclonal antibodies has demonstrated robust LDL-C lowering efficacy of 50-65% and a favorable safety profile. These agents are a promising therapeutic strategy for addressing the unmet needs for additional CVD risk reduction. Regulatory approval for PCSK9 monoclonal antibodies may occur in the near future, and additional agents for PCSK9 inhibition are under development. This review focuses on the mechanism of LDL-C reduction using PCSK9 inhibition, as well as the phase I to III clinical trials of PCSK9 inhibitors. Results of the ongoing phase III CVD outcome trials are eagerly awaited., (Copyright © 2015 Elsevier Inc. All rights reserved.)

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., (© 2015 The Authors. Published on behalf of the American Heart Association, Inc., by Wiley Blackwell.)

The serine protease proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein (LDL) receptor (LDLR) and directs it to the lysosome for degradation. This results in decreased numbers of LDLR available on the cell surface to bind LDL particles and remove them from the circulation and a subsequent increase in circulating LDL-cholesterol (LDL-C) concentrations. Since the role PCSK9 plays in LDL-C metabolism has been discovered in 2003, there have been major efforts in finding efficient and safe methods to inhibit it. Amongst those, the PCSK9 antibodies are the furthest in development, with multiple phase III and cardiovascular endpoint trials already underway. These fully human monoclonal antibodies have been extensively studied in a wide range of subjects such as in those with statin intolerance, as add-on to statin therapy, as monotherapy and in patients with familial hypercholesterolemia. PCSK9 antibodies have shown to be associated with a consistent robust additional decrease in LDL-C concentrations of around 50-70%. If the safety data from the ongoing phase III trials remain as reassuring as the data available till now, PCSK9 antibodies are going to offer a new, powerful therapeutic option to decrease LDL-C concentrations and hopefully cardiovascular risk., (Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.)

The discovery of proprotein convertase subtilisin kexin 9 (PCSK9) has considerably changed the therapeutic options in the field of lipid management. PCSK9 reduces LDL receptor recycling, leading to a decrease of low-density lipoprotein cholesterol (LDL-C) receptors on the surface of hepatocytes and a subsequent increase of circulating LDL-C levels. In observational studies, the loss-of-function mutations of PCSK9 have been associated with a reduction of LDL-C levels and cardiovascular disease (CVD) events. In contrast, humans with high levels of PCSK9 have higher level of plasma LDL-C and significantly enhanced CVD risk during their lifetime, gain-of-function mutations on PCSK9 are, for instance, causatively associated with familial hypercholesterolaemia (FH). Inhibition of PCSK9 is therefore a promising therapeutic option for the lowering of LDL-C levels. The clinical development of human monoclonal antibodies against PCSK9 has progressed, with promising results reported from phase 2 clinical studies in patients with FH or intolerant to statin with LDL-C levels not on target levels. Phase I studies demonstrated safety and efficacy. In phase II, a 60%-70% reduction in LDL-C was observed, especially when subcutaneous injections were performed regularly every two weeks. No significant side effects were observed, with the exception of injection site reactions. Three large phase III programmes with the new anti PCSK9 antibodies are currently underway in patients with acute coronary syndrome (ACS) and LDL-C inadequately controlled by standard treatments. The main objective of these studies is to evaluate the effect of PCSK9 inhibition on the occurrence of CVD events in patients with ACS.

Proprotein convertase subtilisin/kexin type 9 (PCSK9) has emerged as an attractive therapeutic target for cardiovascular disease. Monoclonal antibodies (mAbs) that bind PCSK9 and prevent PCSK9:low-density lipoprotein receptor complex formation reduce serum low-density lipoprotein-cholesterol (LDL-C) in vivo. PCSK9-mediated lysosomal degradation of bound mAb, however, dramatically reduces mAb exposure and limits duration of effect. Administration of high-affinity mAb1:PCSK9 complex (1:2) to mice resulted in significantly lower mAb1 exposure compared with mAb1 dosed alone in normal mice or in PCSK9 knockout mice lacking antigen. To identify mAb-binding characteristics that minimize lysosomal disposition, the pharmacokinetic behavior of four mAbs representing a diverse range of PCSK9-binding affinities at neutral (serum) and acidic (endosomal) pH was evaluated in cynomolgus monkeys. Results revealed an inverse correlation between affinity and both mAb exposure and duration of LDL-C lowering. High-affinity mAb1 exhibited the lowest exposure and shortest duration of action (6 days), whereas mAb2 displayed prolonged exposure and LDL-C reduction (51 days) as a consequence of lower affinity and pH-sensitive PCSK9 binding. mAbs with shorter endosomal PCSK9:mAb complex dissociation half-lives (<20 seconds) produced optimal exposure-response profiles. Interestingly, incorporation of previously reported Fc-region amino acid substitutions or novel loop-insertion peptides that enhance in vitro neonatal Fc receptor binding, led to only modest pharmacokinetic improvements for mAbs with pH-dependent PCSK9 binding, with only limited augmentation of pharmacodynamic activity relative to native mAbs. A pivotal role for PCSK9 in mAb clearance was demonstrated, more broadly suggesting that therapeutic mAb-binding characteristics require optimization based on target pharmacology., (Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.)

Hyperlipidemia is a predominant risk factor for cardiovascular disease (CVD). Statins have been successfully used to treat patients with dyslipidemia and decrease the events of CVD in addition to application of various other non-statin-lowering cholesterol agents, such as ezetimibe and niacin. However, there are still residual risks in patients with atherosclerotic CVD. Recently, proprotein convertase subtilisin/kexin type 9 (PCSK9), which was first identified in 2003, has been suggested to play an important role in the metabolism of low-density lipoprotein cholesterol (LDL-C). PCSK9 degrades the LDL-receptor, which may be pharmacologically targeted to improve the lipoprotein profile and future cardiovascular outcomes in patients with dyslipidemia. Several approaches to inhibiting PCSK9 activity have been theoretically proposed. Among them, monoclonal antibodies have been considered as the most promising strategy because of their large effect on lowering lipids as monotherapy and in combination with statins or ezetimibe. In this review, we mainly focus on the current status of monoclonal antibodies of PCSK9 and clinical trial results for an update on clinical application of monoclonal antibodies of PCSK9. The particular effects of monoclonal antibodies of PCSK9 on lipid profiles are also discussed.

Bioanalytical data from early human studies conducted in normal volunteers are often used for building pharmacokinetic/pharmacodynamic models that can predict outcomes of future studies in diseased patients. Thus, it is important to develop and validate reliable and accurate bioanalytical assays that instill confidence that the intended therapeutic species (total or free) are being measured. Assays quantifying the free therapeutic species, the partially bound (for multivalent therapeutics) and unbound species, require much more characterization than assays that quantify the total therapeutic species. We have developed an immunoassay to measure free BMS-962476, an Adnectin protein therapeutic against soluble proprotein convertase subtilisin kexin (PCSK)-9, and performed an in-depth characterization of the accuracy of this assay with the assistance of modeling. The experimental data correlates with modeled data within 15% at all clinically relevant levels of PCSK9 in normal and diseased populations., (Copyright © 2015 Elsevier B.V. All rights reserved.)

Purpose of Review: Review novel insights into the biology of proprotein convertase subtilisin/kexin 9 (PCSK9) that may explain the extreme efficiency of PCSK9 inhibition and the unexpected metabolic effects resulting from PCSK9 monoclonal antibody therapy, and may identify additional patients as target of therapy., Recent Findings: For over 20 years, the practical knowledge of cholesterol metabolism has centered around cellular mechanisms, and around the idea that statin therapy is the essential step to control metabolic abnormalities for cardiovascular risk management. This view has been embraced by the recent AHA/ACC guidelines, but is being challenged by recent studies including nonstatin medications and by the development of a new class of cholesterol-lowering agents that seems destined to early US Food and Drug Administration approval. The discovery of PCSK9 - a circulating protein that regulates hepatic low-density lipoprotein (LDL) receptor and serum LDL cholesterol levels - has led to a race for its therapeutic inhibition. Recent findings on PCSK9 regulation and pleiotropic effects will help identify additional patient groups likely to benefit from the inhibitory therapy and unravel the full potential of PCSK9 inhibition therapy., Summary: Injectable human monoclonal antibodies to block the interaction between PCSK9 and LDL receptor are demonstrating extraordinary efficacy (LDL reductions of up to 70%) and almost the absence of any side-effects. A more moderate effect is seen on other lipoprotein parameters, with the exception of lipoprotein(a) levels. We describe mechanisms that can explain the effect on lipoprotein(a), predict a potential effect on postprandial triglyderides, and suggest a new category of patients for anti-PCSK9 therapy.

The serine protease proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to the low-density lipoprotein (LDL) receptor (LDLR) and directs it to lysosomes for intracellular degradation. This results in decreased numbers of LDLR available on the hepatic cell surface to bind LDL particles and remove them from the circulation and therefore to a subsequent increase in circulating LDL-cholesterol (LDL-C) plasma levels. Since 2003, when the role of PCSK9 in LDL-C metabolism was discovered, there have been major efforts to develop efficient and safe methods to inhibit it. Amongst those, monoclonal antibodies against PCSK9 are the furthest in development, with multiple phase 3 trials already published and with cardiovascular endpoint trials currently underway. Two fully human monoclonal antibodies, evolocumab (AMG 145) and alirocumab (REGN727/SAR236553), have been extensively studied in a wide range of subjects, such as those with statin intolerance, as an add-on to statin therapy, as a monotherapy and in patients with familial hypercholesterolemia. PCSK9 antibodies result in a consistent and robust decrease in LDL-C plasma levels ranging from 40% to 70%, either on top of statins or as a monotherapy. If the safety data from the on-going phase 3 trials remain as reassuring as the data available till now, PCSK9 antibodies will offer a novel, powerful therapeutic option to decrease LDL-C plasma levels and, hopefully, cardiovascular risk.

Background: Statin intolerance has been a major limitation in the use of statins, especially at higher doses. New effective treatments are needed for lowering low-density lipoprotein cholesterol (LDL-C) in patients who cannot tolerate daily statin doses., Objective: ODYSSEY ALTERNATIVE (NCT01709513) evaluates efficacy and safety of alirocumab, a fully human proprotein convertase subtilisin/kexin type 9 monoclonal antibody, in patients with well-documented statin intolerance and moderate to very high cardiovascular risk., Methods: This is a phase 3, multicenter, randomized, double-blind, double-dummy study in statin-intolerant patients. Intolerance was defined as inability to take at least 2 different statins because of muscle-related adverse events (AEs), 1 at the lowest approved starting dose. Patients first received single-blind subcutaneous and oral placebo for 4 weeks, and were withdrawn if they developed muscle-related AEs after the placebo treatment. Continuing patients were randomized (2:2:1 ratio) to alirocumab 75 mg self-administered via single 1 mL prefilled pen every 2 weeks or ezetimibe 10 mg/day or atorvastatin 20 mg/day (statin rechallenge), for 24 weeks. Alirocumab dose was increased to 150 mg every 2 weeks (also 1 mL) at week 12 depending on week 8 LDL-C level. The primary endpoint is percent change in LDL-C from baseline to week 24 by intent-to-treat analysis. Muscle-related AEs were assessed by spontaneous patient reports and clinic queries., Results: A total of 314 patients have been randomized., Conclusions: This is the first and only study of a new class of LDL-C-lowering agents in patients selected with a rigorously documented intolerance to statins, using a placebo run-in and statin control arm., (Copyright © 2014 National Lipid Association. Published by Elsevier Inc. All rights reserved.)

Background: Alirocumab is a fully human monoclonal antibody to proprotein convertase subtilisin kexin type 9 (PCSK9) under investigation for treatment of hypercholesterolemia and reduction of cardiovascular events., Methods/design: The COMBO studies, part of the Phase 3 ODYSSEY clinical trial program, are designed to evaluate the efficacy and safety of alirocumab as add-on therapy to stable, maximally tolerated daily statin, with or without other lipid-lowering therapy (LLT), in a planned 966 patients with hypercholesterolemia at high cardiovascular risk. COMBO I ( http://clinicaltrials.gov/show/NCT01644175) is placebo-controlled, with a double-blind treatment period of 52 weeks, and 306 planned patients who may receive other LLTs in addition to statin therapy. COMBO II ( http://clinicaltrials.gov/show/NCT01644188) has a double-blind treatment period of 104 weeks, comparing alirocumab with ezetimibe in 660 planned patients receiving statin therapy (but no other LLTs). The primary efficacy endpoint is the difference between treatment arms in percent change in low-density lipoprotein cholesterol (LDL-C) from baseline to week 24. Both studies utilized a starting dose of alirocumab 75 mg every 2 weeks (Q2W; administered as 1 mL solution via auto-injector). Patients with LDL-C levels ≥70 mg/dL after 8 weeks of treatment were up-titrated in a blinded manner at week 12 to alirocumab 150 mg Q2W (also 1 mL auto-injector)., Discussion: In conclusion, the COMBO studies will provide information on the long-term efficacy and safety of alirocumab in high-risk patients when administered in addition to maximally tolerated statin therapy, with a flexible dosing strategy which allows for individualized therapy based on the degree of LDL-C lowering needed to achieve the desired treatment response., Trial Registrations Combo I: NCT01644175 ( NCT01644175)., Combo Ii: NCT01644188 ( NCT01644188).

Aims: Prior trials with monoclonal antibodies to proprotein convertase subtilizin/kexin type 9 (PCSK9) reported robust low density lipoprotein cholesterol (LDL-C) reductions. However, the ability to detect potentially beneficial changes in other lipoproteins such as lipoprotein (a), triglycerides, high-density lipoprotein cholesterol (HDL-C), and apolipoprotein (Apo) A1, and adverse events (AEs) was limited by sample sizes of individual trials. We report a pooled analysis from four phase 2 studies of evolocumab (AMG 145), a monoclonal antibody to PCSK9., Methods and Results: The trials randomized 1359 patients to various doses of subcutaneous evolocumab every 2 weeks (Q2W) or 4 weeks (Q4W), placebo, or ezetimibe for 12 weeks; 1252 patients contributed to efficacy and 1314, to safety analyses. Mean percentage (95% CI) reductions in LDL-C vs. placebo ranged from 40.2% (44.6%, 35.8%) to 59.3% (63.7%, 54.8%) among the evolocumab groups (all P < 0.001). Statistically significant reductions in apolipoprotein B (Apo B), non-high-density lipoprotein cholesterol (non-HDL-C), triglycerides and lipoprotein (a) [Lp(a)], and increases in HDL-C were also observed. Adverse events (AEs) and serious AEs with evolocumab were reported in 56.8 and 2.0% of patients, compared with 49.2% and 1.2% with placebo. Adjudicated cardiac and cerebrovascular events were reported in 0.3 and 0% in the placebo and 0.9 and 0.3% in the evolocumab arms, respectively., Conclusion: In addition to LDL-C reduction, evolocumab, dosed either Q2W or Q4W, demonstrated significant and favourable changes in other atherogenic and anti-atherogenic lipoproteins, and was well tolerated over the 12-week treatment period., (Published on behalf of the European Society of Cardiology. All rights reserved. © The Author 2014. For permissions please email: journals.permissions@oup.com.)

RG7652 is a human IgG1 monoclonal antibody designed to inhibit proprotein convertase subtilisin/kexin type 9 (PCSK9) binding to hepatic low density lipoprotein receptor (LDL-r), thereby blocking PCSK9-mediated degradation of LDL-r. This therapeutic candidate is under development for the prevention of cardiovascular mortality and morbidity in dyslipidemic patients. The primary objective of this study was to evaluate the potential immunotoxicological effects of RG7652 when given to cynomolgus monkeys either alone or in combination with a daily oral dose of atorvastatin. Administration of RG7652 via subcutaneous injection every other week for 12 weeks (a total of seven doses), daily oral doses of atorvastatin (total of 85 doses), and combinations of each up to 15 and 20 mg/kg/dose, respectively, were well tolerated and there was no evidence of alteration in immune function. Administration of pharmacologically relevant doses of RG7652 in combination with atorvastatin to healthy monkeys does not result in clinically meaningful immunosuppression as measured by T-cell dependent antibody responses, natural killer cell activity, immunophenotype, or delayed type hypersensitivity. The only pharmacologically mediated changes observed during the dosing period were the anticipated changes in circulating cholesterol., (© The Author 2014. Published by Oxford University Press on behalf of the Society of Toxicology. All rights reserved. For permissions, please email: journals.permissions@oup.com.)

Objectives: This study sought to evaluate the efficacy and safety of subcutaneous evolocumab compared with oral ezetimibe in hypercholesterolemic patients who are unable to tolerate effective statin doses., Background: Statin intolerance, which is predominantly due to muscle-related side effects, is reported in up to 10% to 20% of patients. Evolocumab, a fully human monoclonal antibody to proprotein convertase subtilisin/kexin type 9 (PCSK9), demonstrated marked reductions in plasma low-density lipoprotein cholesterol (LDL-C) in a phase 2 study in statin-intolerant patients., Methods: The GAUSS-2 (Goal Achievement after Utilizing an Anti-PCSK9 Antibody in Statin Intolerant Subjects) trial was a 12-week, double-blind study of randomized patients (2:2:1:1) to evolocumab 140 mg every two weeks (Q2W) or evolocumab 420 mg once monthly (QM) both with daily oral placebo or subcutaneous placebo Q2W or QM both with daily oral ezetimibe 10 mg. Co-primary endpoints were percent change from baseline in LDL-C at the mean of weeks 10 and 12, and at week 12., Results: Three hundred seven patients (age 62 ± 10 years; LDL-C 193 ± 59 mg/dl) were randomized. Evolocumab reduced LDL-C from baseline by 53% to 56%, corresponding to treatment differences versus ezetimibe of 37% to 39% (p <0.001). Muscle adverse events occurred in 12% of evolocumab-treated patients and 23% of ezetimibe-treated patients. Treatment-emergent adverse events and laboratory abnormalities were comparable across treatment groups., Conclusions: Robust efficacy combined with favorable tolerability makes evolocumab a promising therapy for addressing the largely unmet clinical need in high-risk patients with elevated cholesterol who are statin intolerant. (Goal Achievement After Utilizing an Anti-PCSK9 Antibody in Statin Intolerant Subjects-2; NCT01763905)., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Background: Evolocumab, a monoclonal antibody that inhibits proprotein convertase subtilisin/kexin type 9 (PCSK9), significantly reduced low-density lipoprotein (LDL) cholesterol levels in phase 2 studies. We conducted a phase 3 trial to evaluate the safety and efficacy of 52 weeks of treatment with evolocumab., Methods: We stratified patients with hyperlipidemia according to the risk categories outlined by the Adult Treatment Panel III of the National Cholesterol Education Program. On the basis of this classification, patients were started on background lipid-lowering therapy with diet alone or diet plus atorvastatin at a dose of 10 mg daily, atorvastatin at a dose of 80 mg daily, or atorvastatin at a dose of 80 mg daily plus ezetimibe at a dose of 10 mg daily, for a run-in period of 4 to 12 weeks. Patients with an LDL cholesterol level of 75 mg per deciliter (1.9 mmol per liter) or higher were then randomly assigned in a 2:1 ratio to receive either evolocumab (420 mg) or placebo every 4 weeks. The primary end point was the percent change from baseline in LDL cholesterol, as measured by means of ultracentrifugation, at week 52., Results: Among the 901 patients included in the primary analysis, the overall least-squares mean (±SE) reduction in LDL cholesterol from baseline in the evolocumab group, taking into account the change in the placebo group, was 57.0±2.1% (P<0.001). The mean reduction was 55.7±4.2% among patients who underwent background therapy with diet alone, 61.6±2.6% among those who received 10 mg of atorvastatin, 56.8±5.3% among those who received 80 mg of atorvastatin, and 48.5±5.2% among those who received a combination of 80 mg of atorvastatin and 10 mg of ezetimibe (P<0.001 for all comparisons). Evolocumab treatment also significantly reduced levels of apolipoprotein B, non-high-density lipoprotein cholesterol, lipoprotein(a), and triglycerides. The most common adverse events were nasopharyngitis, upper respiratory tract infection, influenza, and back pain., Conclusions: At 52 weeks, evolocumab added to diet alone, to low-dose atorvastatin, or to high-dose atorvastatin with or without ezetimibe significantly reduced LDL cholesterol levels in patients with a range of cardiovascular risks. (Funded by Amgen; DESCARTES ClinicalTrials.gov number, NCT01516879.).

Statins effectively lower low-density lipoprotein cholesterol (LDL-C), reducing cardiovascular morbidity and mortality. Most patients tolerate statins well, but approximately 10% to 20% experience side effects (primarily muscle-related) contributing to diminished compliance or discontinuation of statin therapy and subsequent increase in cardiovascular risk. Statin-intolerant patients require more effective therapies for lowering LDL-C. Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a compelling target for LDL-C-lowering therapy. Evolocumab (AMG 145) is a fully human monoclonal antibody that binds PCSK9, inhibiting its interaction with the LDL receptor to preserve LDL-receptor recycling and reduce LDL-C. Phase 2 studies have demonstrated the safety, tolerability, and preliminary efficacy of subcutaneous evolocumab in diverse populations, including statin-intolerant patients. This article describes the rationale and design of the Goal Achievement After Utilizing an anti-PCSK9 Antibody in Statin-Intolerant Subjects 2 (GAUSS-2) trial, a randomized, double-blind, ezetimibe-controlled, multicenter phase 3 study to evaluate the effects of 12 weeks of evolocumab 140 mg every 2 weeks or 420 mg every month in statin-intolerant patients with hypercholesterolemia. Eligible subjects were unable to tolerate effective doses of ≥2 statins because of myalgia, myopathy, myositis, or rhabdomyolysis that resolved with statin discontinuation. The primary objective of the study is to assess the effects of evolocumab on percentage change from baseline in LDL-C. Secondary objectives include evaluation of safety and tolerability, comparison of the effects of evolocumab vs ezetimibe on absolute change from baseline in LDL-C, and percentage changes from baseline in other lipids. Recruitment of approximately 300 subjects was completed in August 2013., (© 2014 Wiley Periodicals, Inc.)

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is associated with autosomal dominant hypercholesterolemia, a state of elevated levels of LDL (low-density lipoprotein) cholesterol. Autosomal dominant hypercholesterolemia can result in severe implications such as stroke and coronary heart disease. The inhibition of PCSK9 function by therapeutic antibodies that block interaction of PCSK9 with the epidermal growth factor-like repeat A domain of LDL receptor (LDLR) was shown to successfully lower LDL cholesterol levels in clinical studies. Here we present data on the identification, structural and biophysical characterization and in vitro and in vivo pharmacology of a PCSK9 antibody (mAb1). The X-ray structure shows that mAb1 binds the module 1 of the C-terminal domain (CTD) of PCSK9. It blocks access to an area bearing several naturally occurring gain-of-function and loss-of-function mutations. Although the antibody does not inhibit binding of PCSK9 to epidermal growth factor-like repeat A, it partially reverses PCSK9-induced reduction of the LDLR and LDL cholesterol uptake in a cellular assay. mAb1 is also effective in lowering serum levels of LDL cholesterol in cynomolgus monkeys in vivo. Complete loss of PCSK9 is associated with insufficient liver regeneration and increased risk of hepatitis C infections. Blocking of the CTD is sufficient to partially inhibit PCSK9 function. Antibodies binding the CTD of PCSK9 may thus be advantageous in patients that do not tolerate complete inhibition of PCSK9., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Objectives: This study sought to define the ability of AMG 145, a monoclonal antibody directed against proprotein convertase subtilisin kexin type 9 (PCSK9), to enable subjects at high risk for major adverse cardiovascular events to achieve National Cholesterol Education Program-Adult Treatment Panel III (NCEP-ATP III) parameters for low-density lipoprotein cholesterol (LDL-C) and other lipid goals., Background: Many patients at high risk for adverse cardiovascular events are unable to achieve the NCEP-ATP III LDL-C goal of <70 mg/dl, even with high-potency statin therapy., Methods: In 282 subjects from the LAPLACE-TIMI 57 (LDL-C Assessment with PCSK9 monoclonaL Antibody Inhibition Combined With Statin thErapy-Thrombolysis In Myocardial Infarction 57) trial at high risk according to NCEP-ATP III criteria, we compared the proportion of subjects achieving the NCEP-ATP III recommended LDL-C goal of <70 mg/dl across treatment arms. Other outcomes included the triple goals of LDL-C <70 mg/dl, non-high-density lipoprotein cholesterol (HDL-C) <100 mg/dl, and apolipoprotein B (ApoB) <80 mg/dl., Results: During the dosing interval, more than 90% of subjects in both of the top dose groups every 2 weeks and every 4 weeks attained this lipid target over the dosing interval, with similar success rates for the triple lipid goal., Conclusions: PCSK9 inhibition with AMG 145 enables high-risk patients to achieve established lipid goals. If this therapy demonstrates efficacy for reducing cardiovascular events with a favorable safety profile in ongoing phase 3 trials, we believe it will have major public health implications., (Copyright © 2014 American College of Cardiology Foundation. Published by Elsevier Inc. All rights reserved.)

Objective: To evaluate the monoclonal antibodies to proprotein convertase subtilisin/kexin type 9 (PCSK9) in the management of dyslipidemias., Data Sources: MEDLINE/PubMed, NHS Evidence, TRIP database and EMBASE searches were conducted using the terms proprotein convertase subtilisin/kexin type 9, PCSK9, and monoclonal antibody. No date limits were utilized; search results were current to September 2013., Study Selection and Data Extraction: Articles were limited to phase 2 or 3 clinical trials of monoclonal antibodies to PCSK9 assessing surrogate markers of clinical end points., Data Synthesis: AMG145 and REGN727/SAR236553 are human monoclonal antibodies to PCSK9, a serine protease responsible for low-density lipoprotein cholesterol (LDL-C) regulation. PCSK9 binds to LDL receptors targeting them for intracellular degradation. AMG145 and REGN727/SAR236553 blocks the interaction between PCSK9 and the LDL receptor, increasing LDL receptor availability and allowing the removal of LDL-C from the circulation. These therapies have been evaluated as monotherapy and in combination with statins and ezetimibe in phase 2 trials and have demonstrated significant and dose-related reductions in LDL-C. LDL-C reductions were as high as 72% with REGN727/SAR236553 and 66% with AMG145. These agents were generally well tolerated; nasopharyngitis and injection site reactions were the most common reactions with both agents. Gastrointestinal disturbances and infections were also common with REGN727/SAR236553., Conclusions: These agents may eventually play a role as add-on therapy in those with dyslipidemias because of their significant effect on LDL-C. Further explorations in large phase 3 clinical trials are warranted to evaluate the effect of these therapies on cardiovascular clinical outcomes and long-term safety.

Published phase I and II trials with two fully human monoclonal antibodies to PCSK9 have provided comprehensive evidence that inhibiting PCSK9 is a very effective method to reduce low-density lipoprotein cholesterol (LDL-C). In all populations studied so far, whether on statins or LDL-C-reducing diet alone, with or without a genetic defect in the LDL receptor, and in subjects intolerant to statins, the LDL-C reductions have been large and consistent. Even the most efficacious statin, rosuvastatin, at its highest dose has not achieved such reductions. The clinical trials have established that monoclonal antibody therapy targeted to PCSK9 may be administered subcutaneously every two or four weeks. Current data suggest these drugs will provide an effective therapeutic option for LDL-C reduction and that, if proven safe in phase III trials, they will be as important to LDL-C control, and likely to cardiovascular disease risk reduction, as statins have been over the past three decades.

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death and disability in developed nations, and it is rising rapidly in other parts of the developing world. Levels of low-density lipoprotein cholesterol (LDL-C) are directly correlated with atherogenic risk, and statin-based therapy is the most common management for these patients. However, many patients exhibit resistance to and/or adverse effects from statin therapy, and there is a need for adjunctive therapies or statin alternatives for these patients. The recently discovered human protein proprotein convertase subtilisin/kexin type 9 (PCSK9) plays an important role in LDL-C metabolism. PCSK9 promotes LDL receptor (LDL-R) degradation with a consequent reduction in LDL-R density and an increase in LDL-C levels. Consequently, PCSK9 inhibition to reduce LDL-C levels has become a primary focus for drug development. Numerous clinical trials focusing on monoclonal antibodies against PCSK9 have demonstrated efficacy equal to or greater than statin therapy for lowering LDL-C levels. Long-term trials are underway to assess safety, tolerability, and ability to reduce ASCVD.

RG7652 is a human immunoglobulin 1 (IgG1) monoclonal antibody (mAb) targeting proprotein convertase subtilisin/kexin type 9 (PCSK9) and is designed for the treatment of hypercholesterolemia. A target-binding enzyme-linked immunosorbent assay (ELISA) was developed to measure RG7652 levels in human serum in a Phase I study. Although target-binding assay formats are generally used to quantify free therapeutic, the actual therapeutic species being measured are affected by assay conditions, such as sample dilution and incubation time, and levels of soluble target in the samples. Therefore, in the presence of high concentrations of circulating target, the choice of reagents and assay conditions can have a significant effect on the observed pharmacokinetic (PK) profiles. Phase I RG7652 PK analysis using the ELISA data resulted in a nonlinear dose normalized exposure. An investigation was conducted to characterize the ELISA to determine whether the assay format and reagents may have contributed to the PK observation. In addition, to confirm the ELISA results, a second orthogonal method, liquid chromatography tandem mass spectrometry (LC-MS/MS) using a signature peptide as surrogate, was developed and implemented. A subset of PK samples, randomly selected from half of the subjects in the 6 single ascending dose (SAD) cohorts in the Phase I clinical study, was analyzed with the LC-MS/MS assay, and the data were found to be comparable to the ELISA data. This paper illustrates the importance of reagent characterization, as well as the benefits of using an orthogonal approach to eliminate bioanalytical contributions when encountering unexpected observations.

Atherosclerotic cardiovascular disease (ASCVD) is the leading cause of death and disability in the United States and other developed nations, and is rising rapidly in the rest of the world. Low-density lipoprotein (LDL) is the major atherogenic particle in most patients at high risk for ASCVD events, and statin-based LDL-lowering treatment is the major focus of treatment for prevention of ASCVD. Despite this, an estimated 57 million US adults (25%) still have moderately elevated levels of LDL-cholesterol (LDL-C) > 160 mg/dL, and many others have an LDL-C above the level considered appropriate for their high-risk status. Although statins are very effective for lowering LDL-C, and other classes of LDL-lowering medications are available, many patients still cannot achieve adequate LDL-lowering with maximal tolerated doses of US Food and Drug Administration-approved treatments. Thus, there is an unmet medical need for statin adjuncts in these patients, as well as for statin alternatives in statin-intolerant patients. A recently discovered human protein, proprotein convertase subtilisin/kexin type 9 (PCSK9), plays an important role in LDL metabolism by promoting degradation of the LDL receptor, and thus reducing clearance of LDL and increasing LDL-C levels. Accordingly, inhibition of PCSK9 activity has become an attractive target for drug development for lowering LDL-C, and human monoclonal antibodies against PCSK9, are now in late-stage clinical development. These antibodies are at least as effective as statins for LDL-C lowering (or more so), and their effects are additive to those of statins. To date, they have been well tolerated and apparently safe in clinical trials. Long-term randomized, controlled trials of their safety, tolerability, and ability to reduce ASCVD are now underway.

Background: Homozygous familial hypercholesterolemia is a rare, serious disorder with a substantial reduction in low-density lipoprotein (LDL) receptor function, severely elevated LDL cholesterol, cardiovascular disease, and often death in childhood. Response to conventional drug therapies is modest. Monoclonal antibodies to proprotein convertase subtilisin/kexin 9 (PCSK9) reduce LDL cholesterol in heterozygous familial hypercholesterolemia. The effect in homozygous familial hypercholesterolemia is unknown and uncertain. We evaluated the efficacy and safety of AMG 145 in an open-label, single-arm, multicenter, dose-scheduling pilot study in patients with homozygous familial hypercholesterolemia., Methods and Results: Eight patients with LDL receptor-negative or -defective homozygous familial hypercholesterolemia on stable drug therapy were treated with subcutaneous 420 mg AMG 145 every 4 weeks for ≥12 weeks, followed by 420 mg AMG 145 every 2 weeks for an additional 12 weeks. All patients completed both treatment periods. Mean change from baseline in LDL cholesterol at week 12 was -16.5% (range, 5.2% to -43.6%; P=0.0781) and -13.9% (range, 39.9% to -43.3%; P=0.1484) with 4- and 2-week dosing, respectively. No reduction was seen in the 2 receptor-negative patients. Over the treatment periods, mean±SD LDL cholesterol reductions in the 6 LDL receptor-defective patients were 19.3±16% and 26.3±20% with 4- and 2-week dosing, respectively (P=0.0313 for both values), ranging from 4% to 48% with 2-week dosing. No serious side effects were reported., Conclusion: This study demonstrates significant and dose-related LDL cholesterol lowering with a PCSK9 monoclonal antibody in homozygous familial hypercholesterolemia patients with defective LDL receptor activity but no reduction in those who were receptor negative.

Background: Lipoprotein(a) [Lp(a)] is an emerging risk factor for cardiovascular disease. Currently, there are few available therapies to lower Lp(a). We sought to evaluate the impact of AMG145, a monoclonal antibody against proprotein convertase subtilisin kexin type 9 (PCSK9), on Lp(a)., Methods and Results: As part of the LDL-C Assessment With PCSK9 Monoclonal Antibody Inhibition Combined With Statin Therapy (LAPLACE)-Thrombolysis in Myocardial Infarction (TIMI) 57 trial, 631 patients with hypercholesterolemia receiving statin therapy were randomized to receive AMG145 at 1 of 3 different doses every 2 weeks or 1 of 3 different doses every 4 weeks versus placebo. Lp(a) and other lipid parameters were measured at baseline and at week 12. Compared with placebo, AMG145 70 mg, 105 mg, and 140 mg every 2 weeks reduced Lp(a) at 12 weeks by 18%, 32%, and 32%, respectively (P<0.001 for each dose versus placebo). Likewise, AMG145 280 mg, 350 mg, and 420 mg every 4 weeks reduced Lp(a) by 18%, 23%, and 23%, respectively (P<0.001 for each dose versus placebo). The reduction in Lp(a) correlated with the reduction in low-density lipoprotein cholesterol (ρ=0.33, P<0.001). The effect of AMG145 on Lp(a) was consistent regardless of age, sex, race, history of diabetes mellitus, and background statin regimen. Patients with higher levels of Lp(a) at baseline had larger absolute reductions but comparatively smaller percent reductions in Lp(a) with AMG145 compared with those with lower baseline Lp(a) values., Conclusions: AMG145 significantly reduces Lp(a), by up to 32%, among subjects with hypercholesterolemia receiving statin therapy, offering an additional, complementary benefit beyond robust low-density lipoprotein cholesterol reduction with regard to a patient's atherogenic lipid profile.

Monoclonal antibodies (mAbs) are established therapies for many conditions, including cancers, autoimmune conditions and infectious diseases. mAbs can offer benefits over conventional pharmacotherapy in terms of potency, dosing frequency and specificity for their target antigen. Mouse-derived antibodies were initially used in humans; however, patients often developed human anti-mouse antibodies, resulting in rapid antibody clearance (and a resulting loss of efficacy) and hypersensitivity reactions. Chimeric, humanized, and fully human antibodies were thus developed, with increasing amounts of human sequence, to reduce immunogenicity. Although generally well tolerated, mAbs may be associated with adverse events (AEs). Many AEs are target-related, and will be specific to the antibody target and the therapeutic area of use. However, off-target AEs, such as hypersensitivity reactions, are observed with many antibodies. Within the realm of cardiovascular medicine, new antibody-based therapies are under investigation to reduce low-density lipoprotein cholesterol (LDL-C) levels. Proprotein convertase subtilisin/kexin type 9 (PCSK9) regulates plasma LDL-C levels by increasing degradation of the LDL receptor (LDLR). Therefore, inhibition of the interaction between PCSK9 and the LDLR with mAbs targeting PCSK9 has great potential for patients with hypercholesterolaemia. Early clinical phase studies suggest these mAbs are effective and well tolerated; however, further studies are required to assess their long-term safety., (Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.)

Context: An estimated 10% to 20% of patients cannot tolerate statins or adequate doses to achieve treatment goals. Plasma proprotein convertase subtilisin/kexin type 9 (PCSK9) binds to low-density lipoprotein (LDL) receptors, promoting their degradation and increasing LDL cholesterol levels. In phase 1 studies, a human monoclonal antibody to PCSK9, AMG145, was well tolerated and reduced LDL cholesterol levels., Objective: To assess the efficacy and tolerability of AMG145 in patients with statin intolerance due to muscle-related side effects., Design, Setting, and Patients: A 12-week, randomized, double-blind, placebo- and ezetimibe-controlled, dose-ranging study conducted between July 2011 and May 2012 in statin-intolerant adult patients at 33 international sites., Intervention: Patients were randomized equally to 1 of 5 groups: AMG145 alone at doses of 280 mg, 350 mg, or 420 mg; AMG145 at 420 mg plus 10 mg of ezetimibe; or 10 mg of ezetimibe plus placebo. AMG145 or placebo was administered subcutaneously every 4 weeks., Main Outcome Measures: The primary end point was percentage change from baseline to week 12 in ultracentrifugation-measured LDL cholesterol. Other end points included measures of safety and tolerability of different doses of AMG145 and AMG145 plus ezetimibe., Results: Of 236 patients screened, 160 were randomized (mean age, 62 years; 64% female; mean baseline LDL cholesterol, 193 mg/dL); all patients had intolerance to 1 or more statins because of muscle-related events. At week 12, mean changes in LDL cholesterol levels were -67 mg/dL (-41%; 95% CI, -49% to -33%) for the AMG145, 280-mg, group; -70 mg/dL (-43%; 95% CI, -51% to -35%) for the 350-mg group; -91 mg/dL (-51%; 95% CI, -59% to -43%) for the 420-mg group; and -110 mg/dL (-63%; 95% CI, -71% to -55%) for the 420-mg/ezetimibe group compared with -14 mg/dL (-15%; 95% CI, -23% to -7.0%) for the placebo/ezetimibe group (P < .001). Four serious adverse events were reported with AMG145 (coronary artery disease, acute pancreatitis, hip fracture, syncope). Myalgia was the most common treatment-emergent adverse event during the study, occurring in 5 patients (15.6%) in the 280-mg group (n = 32); 1 patient (3.2%) in the 350-mg group (n = 31), 1 patient (3.1%) in the 420-mg group (n = 32), 6 patients (20.0%) receiving 420-mg AMG145/ezetimibe, and 1 patient (3.1%) receiving placebo/ezetimibe., Conclusion: In this phase 2 study in statin-intolerant patients, subcutaneous administration of a monoclonal antibody to PCSK9 significantly reduced LDL cholesterol levels and was associated with short-term tolerability. TRIAL REGISTRATION clinicaltrials.gov Identifier: NCT01375764.

Background: Proprotein convertase subtilisin/kexin type 9 (PCSK9) increases serum LDL-cholesterol (LDL-C) concentrations. We assessed the effects of AMG 145, a human monoclonal antibody against PCSK9, in patients with hypercholesterolaemia in the absence of concurrent lipid-lowering treatment., Methods: In a phase 2 trial done at 52 centres in Europe, the USA, Canada, and Australia, patients (aged 18-75 years) with serum LDL-C concentrations of 2·6 mmol/L or greater but less than 4·9 mmol/L were randomly assigned equally through an interactive voice response system to subcutaneous injections of AMG 145 70 mg, 105 mg, or 140 mg, or placebo every 2 weeks; subcutaneous AMG 145 280 mg, 350 mg, or 420 mg or placebo every 4 weeks; or oral ezetimibe 10 mg/day. The primary endpoint was percentage change from baseline in LDL-C concentration at week 12. Analysis was by modified intention to treat. Study personnel and patients were masked to treatment assignment of AMG 145 or placebo. Ezetimibe assignment was open label. This trial is registered with ClinicalTrials.gov, number NCT01375777., Findings: 406 patients were assigned to AMG 145 70 mg (n=45), 105 mg (n=46), or 140 mg (n=45) every 2 weeks; AMG 145 280 mg (n=45), 350 mg (n=45), or 420 mg (n=45) every 4 weeks; placebo every 2 weeks (n=45) or every 4 weeks (n=45); or ezetimibe (n=45). AMG 145 significantly reduced LDL-C concentrations in all dose groups (mean baseline LDL-C concentration 3·7 mmol/L [SD 0·6]; changes from baseline with every 2 weeks AMG 145 70 mg -41·0% [95% CI -46·2 to -35·8]; 105 mg -43·9% [-49·0 to -38·7]; 140 mg -50·9% [-56·2 to -45·7]; every 4 weeks AMG 145 280 mg -39·0% [-44·1 to -34·0]; 350 mg -43·2% [-48·3 to -38·1]; 420 mg -48·0% [-53·1 to -42·9]; placebo every 2 weeks -3·7% [-9·0 to 1·6]; placebo every 4 weeks 4·5% [-0·7 to 9·8]; and ezetimibe -14·7% [-18·6 to -10·8]; p<0·0001 for all doses vs placebo or ezetimibe). Treatment-emergent adverse events occurred in 136 (50%) of 271 patients in the AMG 145 groups, 41 (46%) of 90 patients in the placebo groups, and 26 (58%) of 45 patients in the ezetimibe group; no deaths or serious treatment-related adverse events were reported., Interpretation: The results of our study support the further assessment of AMG 145 in long-term studies with larger and more diverse populations including patients with documented statin intolerance., Funding: Amgen., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: LDL cholesterol (LDL-C) is a well established risk factor for cardiovascular disease. Proprotein convertase subtilisin/kexin type 9 (PCSK9) binds LDL receptors, targeting them for degradation. We therefore assessed the efficacy, safety, and tolerability of AMG 145, a human monoclonal IgG2 antibody against PCSK9, in stable patients with hypercholesterolemia on a statin., Methods: In a phase 2, dose-ranging study done in 78 centres in the USA, Canada, Denmark, Hungary, and Czech Republic, patients (aged 18-80 years) with LDL-C greater than 2·2 mmol/L on a stable dose of statin (with or without ezetimibe), were randomly assigned equally, through an interactive voice response system, to subcutaneous injections of AMG 145 70 mg, 105 mg, or 140 mg, or matching placebo every 2 weeks; or subcutaneous injections of AMG 145 280 mg, 350 mg, or 420 mg, or matching placebo every 4 weeks. Everyone was masked to treatment assignment within the every 2 weeks and every 4 weeks schedules. The primary endpoint was the percentage change in LDL-C concentration from baseline after 12 weeks. Analysis was by modified intention to treat. This study is registered with ClinicalTrials.gov, number NCT01380730., Findings: 631 patients with hypercholesterolaemia were randomly assigned to AMG 145 70 mg (n=79), 105 mg (n=79), or 140 mg (n=78), or matching placebo (n=78) every 2 weeks; or AMG 145 280 mg (n=79), 350 mg (n=79), and 420 mg (n=80), and matching placebo (n=79) every 4 weeks. At the end of the dosing interval at week 12, the mean LDL-C concentrations were reduced generally dose dependently by AMG 145 every 2 weeks (ranging from 41·8% to 66·1%; p<0·0001 for each dose vs placebo) and AMG 145 every 4 weeks (ranging from 41·8% to 50·3%; p<0·0001). No treatment-related serious adverse events occurred. The frequencies of treatment-related adverse events were similar in the AMG 145 and placebo groups (39 [8%] of 474 vs 11 [7%] of 155); none of these events were severe or life-threatening., Interpretation: The results suggest that PCSK9 inhibition could be a new model in lipid management. Inhibition of PCSK9 warrants assessment in phase 3 clinical trials., Funding: Amgen., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: Despite statin treatment, many patients with heterozygous familial hypercholesterolemia do not reach desired low-density lipoprotein cholesterol (LDL-C) targets. AMG 145, a fully human monoclonal antibody against proprotein convertase subtilisin/kexin type 9 (PCSK9) serine protease, demonstrated significant reductions in LDL-C in phase 1 studies. This phase 2, multicenter, double-blind, randomized, placebo-controlled, dose-ranging study evaluated the efficacy and safety of AMG 145 in heterozygous familial hypercholesterolemia patients., Methods and Results: Patients with heterozygous familial hypercholesterolemia diagnosed by Simon Broome criteria with LDL-C ≥2.6 mmol/L (100 mg/dL) despite statin therapy with or without ezetimibe were randomized 1:1:1 to AMG 145 350 mg, AMG 145 420 mg, or placebo-administered subcutaneously every 4 weeks. The primary end point was percentage change from baseline in LDL-C at week 12. Of 168 patients randomized, 167 received investigational product and were included in the full analysis set (mean [SD] age, 50 [13] years; 47% female; 89% white; mean [SD] baseline LDL-C, 4.0 [1.1] mmol/L (156 [42] mg/dL)). At week 12, LDL-C reduction measured by preparative ultracentrifugation (least squares mean [standard error (SE)]) was 43 (3)% and 55 (3)% with AMG 145 350 mg and 420 mg, respectively, compared with 1 (3)% increase with placebo (P<0.001 for both dose groups). Serious adverse events (not considered treatment-related) occurred in 2 patients on AMG 145., Conclusions: AMG 145 administered every 4 weeks yielded rapid and substantial reductions in LDL-C in heterozygous familial hypercholesterolemia patients despite intensive statin use, with or without ezetimibe, with minimal adverse events and good tolerability., Clinical Trial Registration: URL: http://www.clinicaltrials.gov. Unique identifier: NCT01375751.

Background: 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., Methods: 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., Findings: 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., Interpretation: 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., Funding: Sanofi US and Regeneron Pharmaceuticals Incorporated., (Copyright © 2012 Elsevier Ltd. All rights reserved.)

Background: Proprotein convertase subtilisin/kexin 9 (PCSK9), one of the serine proteases, binds to low-density lipoprotein (LDL) receptors, leading to their accelerated degradation and to increased LDL cholesterol levels. We report three phase 1 studies of a monoclonal antibody to PCSK9 designated as REGN727/SAR236553 (REGN727)., Methods: In healthy volunteers, we performed two randomized, single ascending-dose studies of REGN727 administered either intravenously (40 subjects) or subcutaneously (32 subjects), as compared with placebo. These studies were followed by a randomized, placebo-controlled, multiple-dose trial in adults with heterozygous familial hypercholesterolemia who were receiving atorvastatin (21 subjects) and those with nonfamilial hypercholesterolemia who were receiving treatment with atorvastatin (30 subjects) (baseline LDL cholesterol, >100 mg per deciliter [2.6 mmol per liter]) or a modified diet alone (10 subjects) (baseline LDL cholesterol, >130 mg per deciliter [3.4 mmol per liter]). REGN727 doses of 50, 100, or 150 mg were administered subcutaneously on days 1, 29, and 43. The primary outcome for all studies was the occurrence of adverse events. The principal secondary outcome was the effect of REGN727 on the lipid profile., Results: Among subjects receiving REGN727, there were no discontinuations because of adverse events. REGN727 significantly lowered LDL cholesterol levels in all the studies. In the multiple-dose study, REGN727 doses of 50, 100, and 150 mg reduced measured LDL cholesterol levels in the combined atorvastatin-treated populations to 77.5 mg per deciliter (2.00 mmol per liter), 61.3 mg per deciliter (1.59 mmol per liter), and 53.8 mg per deciliter (1.39 mmol per liter), for a difference in the change from baseline of -39.2, -53.7, and -61.0 percentage points, respectively, as compared with placebo (P<0.001 for all comparisons)., Conclusions: In three phase 1 trials, a monoclonal antibody to PCSK9 significantly reduced LDL cholesterol levels in healthy volunteers and in subjects with familial or nonfamilial hypercholesterolemia. (Funded by Regeneron Pharmaceuticals and Sanofi; ClinicalTrials.gov numbers, NCT01026597, NCT01074372, and NCT01161082.).

Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a promising therapeutic target for treating coronary heart disease. We report a novel antibody 1B20 that binds to PCSK9 with sub-nanomolar affinity and antagonizes PCSK9 function in-vitro. In CETP/LDLR-hemi mice two successive doses of 1B20, administered 14 days apart at 3 or 10 mpk, induced dose dependent reductions in LDL-cholesterol (≥ 25% for 7-14 days) that correlated well with the extent of PCSK9 occupancy by the antibody. In addition, 1B20 induces increases in total plasma antibody-bound PCSK9 levels and decreases in liver mRNA levels of SREBP-regulated genes PCSK9 and LDLR, with a time course that parallels decreases in plasma LDL-cholesterol (LDL-C). Consistent with this observation in mice, in statin-responsive human primary hepatocytes, 1B20 lowers PCSK9 and LDLR mRNA levels and raises serum steady-state levels of antibody-bound PCSK9. In addition, mRNA levels of several SREBP regulated genes involved in cholesterol and fatty-acid synthesis including ACSS2, FDPS, IDI1, MVD, HMGCR, and CYP51A1 were decreased significantly with antibody treatment of primary human hepatocytes. In rhesus monkeys, subcutaneous (SC) dosing of 1B20 dose-dependently induces robust LDL-C lowering (maximal ~70%), which is correlated with increases in target engagement and total antibody-bound PCSK9 levels. Importantly, a combination of 1B20 and Simvastatin in dyslipidemic rhesus monkeys reduced LDL-C more than either agent alone, consistent with a mechanism of action that predicts additive effects of anti-PCSK9 agents with statins. Our results suggest that antibodies targeting PCSK9 could provide patients powerful LDL lowering efficacy on top of statins, and lower cardiovascular risk.

Carboxyl terminal processing protease of D1 protein (CtpA) catalyzes carboxyl terminal processing of D1 protein, which is predicted to be an excellent target for a general broad-spectrum herbicide. In this study, the CtpA gene from spinach cDNA was cloned and overexpressed and the recombinant CtpA fusion protein (rCtpA) was used as antigen to immunize BALB/c mice for the production of monoclonal antibody (MAb). Western blot and ELISA results indicated that both rCtpA and the PDZ domain protein of CtpA had specific binding abilities to MAbs, while the specificity and sensitivity of rCtpA were much higher than that of the PDZ domain. These results suggest that parts of the antigen determinant of CtpA were located in the PDZ domain. The MAbs and related results obtained in this study proved the feasibility of high-throughput screening of lead compounds for protease as inhibitors and mechanism analysis of CtpA enzyme.