PCSK9 Inhibitors: Clinical Relevance, Molecular Mechanisms, and Safety in Clinical Practice / Inibidores de PCSK9: Importância Clínica, Mecanismos Moleculares, e Segurança na Prática Clínica

Abstract Coronary artery disease (CAD) is one of the leading causes of mortality. High circulating levels of low-density lipoprotein (LDL) in the blood are associated with cardiovascular mortality, whether through an etiological role or through its association with the progression of CAD per se. Randomized clinical trials have shown that, when LDL levels are reduced, cardiovascular risk is also reduced, which reinforces this association. The first major trial involving a hypolipidemic agent of the statin family, the Scandinavian Simvastatin Survival Study (4S), was published in 1994 and found a significant reduction in mortality in patients at high cardiovascular risk. However, even in subsequent studies with different statins, a residual risk persisted, and this seems not to have changed over time; it is speculated that this risk may be due to statin intolerance. In this scenario, the potential exists for novel hypolipidemic agents to drive a true revolution in the therapy of dyslipidemia. The recent discovery of PCSK9 inhibitors (PCSK9i), a class of hypolipidemic monoclonal antibodies, is extremely promising. PCSK9 inhibition is capable of promoting a mean LDL reduction of up to 60%, with potential for very significant clinical repercussions, as every 38 mg/dL reduction in LDL appears to be associated with a 22% reduction in cardiovascular risk. This review addresses a brief history of PCSK9i, major trials of these drugs, cardiovascular outcomes, and aspects related to their efficacy and safety. Finally, the molecular mechanisms and possible pleiotropic effects of PCSK9i are also discussed.

Resumo A doença arterial coronariana (DAC) é uma das principais causas de mortalidade. Níveis circulantes elevados de lipoproteína de baixa densidade (LDL) no sangue estão associados com mortalidade cardiovascular, seja por um papel etiológico ou por sua associação com a progressão da DAC em si. Estudos clínicos randomizados mostram que, quando os níveis de LDL são reduzidos, o risco cardiovascular também é reduzido, o que reforça tal associação. O primeiro ensaio importante envolvendo um agente hipolipemiante da família da estatina, o estudo Scandinavian Simvastatin Survival Study (4S), foi publicado em 1994 e encontrou uma redução significativa na mortalidade de pacientes com risco cardiovascular elevado. Contudo, mesmo em estudos subsequentes com diferentes estatinas, observou-se um risco residual persistente, o qual aparentemente não mudou ao longo dos anos. Especula-se que esse risco se deve à intolerância às estatinas. Nesse cenário, existe um potencial para novos agentes hipolipemiantes que levem a uma verdadeira revolução no tratamento das dislipidemias. A descoberta recente dos inibidores de PCSK9 (PCSK9i), uma classe de anticorpos monoclonais, é extremamente promissora. A inibição da PCSK9 é capaz de promover uma redução média nos níveis de LDL de até 60%, com potencial para repercussões clínicas muito significativas, já que para cada redução de 38 mg/dL, parece haver uma redução de 22% no risco cardiovascular. Esta revisão aborda uma breve história dos PCSK9i, os principais ensaios envolvendo esses medicamentos, desfechos cardiovasculares, e aspectos relacionados a sua eficácia e segurança. Finalmente, os mecanismos moleculares e possíveis efeitos pleiotrópicos dos PCSK9i são também discutidos.

Serum Levels of PCSK9 Are Associated with Coronary Angiographic Severity in Patients with Acute Coronary Syndrome

BACKGROUND: Proprotein convertase subtilisin/kexin type 9 (PCSK9) is a circulating protein that promotes degradation of the low density lipoprotein receptor. PCSK9 has emerged as a target for lipid-lowering therapy, but the predictive value of the serum level of PCSK9 for the severity of coronary disease is largely unknown. METHODS: From December 2009 to July 2012, 121 individuals who underwent coronary angiography (CAG) because of clinically suspected acute coronary syndrome were enrolled in this study. Serum levels of PCSK9 and metabolic parameters were measured. SYNTAX (SYNergy between percutaneous coronary intervention with [paclitaxel-eluting] TAXUS stent and cardiac surgery) and GRACE (Global Registry of Acute Coronary Events) scores were calculated. RESULTS: Individuals with CAG lesions (n=100) had significantly higher levels of PCSK9 than those without lesions (n=21). The study population was stratified into three groups according to serum levels of PCSK9. The odds radio for occurrence of one or more CAG lesions was significantly higher in the group with the highest level of PCSK9 (odds ratio, 7.468; P=0.011) than in the group with the lowest level of PCSK9. Serum PCSK9 was positively associated with the number of involved coronary arteries. Multivariable linear regression indicated that levels of PCSK9 were positively correlated with GRACE risk scores and SYNTAX scores. CONCLUSION: Serum PCSK9 concentrations are higher in patients with coronary artery lesions, and are associated with SYNTAX and GRACE scores, suggesting that PCSK9 is a potential biomarker of the severity of coronary artery disease.