Factorial Effects of Evolocumab and Atorvastatin on Lipoprotein Metabolism.

BACKGROUND: Monoclonal antibodies against proprotein convertase subtilisin kexin type 9 (PCSK9), such as evolocumab, lower plasma low-density lipoprotein (LDL)-cholesterol concentrations. Evolocumab is under investigation for its effects on cardiovascular outcomes in statin-treated, high-risk patients. The mechanism of action of PCSK9 monoclonal antibodies on lipoprotein metabolism remains to be fully evaluated. Stable isotope tracer kinetics can effectively elucidate the mode of action of new lipid-regulating pharmacotherapies. METHODS: We conducted a 2-by-2 factorial trial of the effects of atorvastatin (80 mg daily) and subcutaneous evolocumab (420 mg every 2 weeks) for 8 weeks on the plasma kinetics of very-low-density lipoprotein (VLDL)-apolipoprotein B-100 (apoB), intermediate-density lipoprotein-apoB, and LDL-apoB in 81 healthy, normolipidemic, nonobese men. The kinetics of apoB in these lipoproteins was studied using a stable isotope infusion of D3-leucine, gas chromatography/mass spectrometry, and multicompartmental modeling. RESULTS: Atorvastatin and evolocumab independently accelerated the fractional catabolism of VLDL-apoB (P<0.001 and P.032, respectively), intermediate-density lipoprotein-apoB (P=0.021 and P=.002, respectively), and LDL-apoB (P<0.001, both interventions). Evolocumab but not atorvastatin decreased the production rate of intermediate-density lipoprotein-apoB (P=0.043) and LDL-apoB (P<0.001), which contributed to the reduction in the plasma pool sizes of these lipoprotein particles. The reduction in LDL-apoB and LDL-cholesterol concentrations was significantly greater with combination versus either monotherapy (P<0.001). Whereas evolocumab but not atorvastatin lowered the concentration of free PCSK9, atorvastatin lowered the lathosterol/campesterol ratio (a measure of cholesterol synthesis/absorption) and apoC-III concentration. Both interventions decreased plasma apoE, but neither significantly altered lipoprotein lipase and cholesteryl ester protein mass or measures of insulin resistance. CONCLUSIONS: In healthy, normolipidemic subjects, evolocumab decreased the concentration of atherogenic lipoproteins, particularly LDL, by accelerating their catabolism. Reductions in intermediate-density lipoprotein and LDL production also contributed to the decrease in LDL particle concentration with evolocumab by a mechanism distinct from that of atorvastatin. These kinetic findings provide a metabolic basis for understanding the potential benefits of PCSK9 monoclonal antibodies incremental to statins in on-going clinical end point trials. CLINICAL TRIAL REGISTRATION: URL: http://www.clinicaltrials.gov. Unique identifier: NCT02189837.

Effect of the proprotein convertase subtilisin/kexin 9 monoclonal antibody, AMG 145, in homozygous familial hypercholesterolemia.

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.

Biologics for the treatment of dyslipidemias: a look beyond conventional therapy.

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.

Evaluation of Evolocumab (AMG 145), a Fully Human Anti-PCSK9 IgG2 Monoclonal Antibody, in Subjects With Hepatic Impairment.

Evolocumab binds PCSK9, increasing low-density lipoprotein cholesterol (LDL-C) receptors and lowering LDL-C. Target-mediated evolocumab elimination is attributable to PCSK9 binding. As circulating PCSK9 and LDL-C levels are primarily regulated by the liver, we compared evolocumab pharmacokinetics, pharmacodynamics, and safety in individuals with and without hepatic impairment. An open-label, parallel-group study evaluated the pharmacokinetics of evolocumab in hepatic-impaired (Child-Pugh Class A or B) or healthy adults. Participants were classified as having no, mild, or moderate hepatic impairment (n = 8/group) and received a single 140-mg evolocumab dose. Assessments of unbound evolocumab and PCSK9 were made predose and postdose. Adverse events were monitored throughout the study. No significant association was observed between baseline PCSK9 and increasing level of hepatic impairment. No difference in extent and time course of PCSK9 or LDL-C reduction was observed despite an apparent decrease in mean unbound evolocumab exposure with increasing hepatic impairment (Jonckheere-Terpstra trend test; maximum serum concentration P = .18; area under the curve P = .09). Maximum reductions were observed in moderately impaired subjects vs healthy individuals: mean maximum serum concentration -34%; mean area under the concentration-time curve (AUC) -47%. On average, unbound PCSK9 serum concentrations fell by >80% at 4 hours after a single evolocumab dose. Mean (95% confidence interval) maximum LDL-C reductions in the healthy, mild, and moderate groups were -57% (-64% to -48%), -70% (-75% to -63%), and -53% (-61% to -43%), respectively. No safety risks were identified. These results support evolocumab use without dose adjustment in patients with active liver disease and mild or moderate hepatic impairment.

Profile of evolocumab and its potential in the treatment of hyperlipidemia.

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

Efficacy and safety profile of evolocumab (AMG145), an injectable inhibitor of the proprotein convertase subtilisin/kexin type 9: the available clinical evidence.

INTRODUCTION: Despite the proven efficacy of statins, they are often reported to be inadequate to achieve low-density lipoprotein cholesterol (LDL-C) goals (especially in high-risk patients). Moreover, a large number of subjects cannot tolerate statins or full doses of these drugs. Thus, there is a need for additional effective LDL-C reducing agents. AREAS COVERED: Evolocumab (AMG145) is a monoclonal antibody inhibiting the proprotein convertase subtilisin/kexin type 9 that binds to the liver LDL receptor and prevents it from normal recycling by targeting it for degradation. Phase I and II trials revealed that its subcutaneous injection, either alone or in combination with statins, is able to reduce LDL-C from 40 to 80%, apolipoprotein B100 from 30 to 59% and lipoprotein(a) from 18 to 36% in a dose-dependent manner. The incidence of side effects seems to be low and mainly limited to nasopharyngitis, injection site pain, arthralgia and back pain. EXPERT OPINION: Evolocumab is an innovative powerful lipid-lowering drug, additive to statins and with an apparently large therapeutic range associated to a low rate of mild adverse events. If available data will be confirmed in long-term trials with strong outcomes, Evolocumab will provide an essential tool to treat high-risk patients who need to reach ambitious LDL-C target.