Targeting PCSK9 With Antibodies and Gene Silencing to Reduce LDL Cholesterol.

The discovery of PCSK9 and its role in regulating the low-density lipoprotein (LDL) receptor, and the effect of loss-of-function mutations of its gene, identified it as a therapeutic target in 2006. Fully humanized monoclonal antibodies to PCSK9 (alirocumab and evolocumab) proved effective for lowering LDL cholesterol and subsequently for reducing atherosclerotic events in large outcome trials. Suppressing PCSK9 synthesis via gene silencing using inclisiran, a small interfering RNA, is another approach that effectively reduces LDL cholesterol, and a cardiovascular outcome trial is in progress. These treatments are given subcutaneously on a background of maximally tolerated statin treatment and are long-lasting: dosing is once or twice a month, self-administered, for alirocumab and evolocumab, and every 6 months for inclisiran, in the clinic, with an extra dose at 3 months in the initial year of therapy. These 3 agents produce mean LDL reductions of about 55% with no important adverse effects detectable to date. They are indicated in patients with atherosclerotic vascular disease or familial hypercholesterolemia who cannot achieve LDL cholesterol targets with maximally tolerated statin treatment. Such therapy can produce very low plasma LDL cholesterol and PCSK9, but there is no evidence this is harmful. Introduction into clinical practice has been impeded by economic considerations. The barrier to their use has not been scientific or medical, but rather the impact on healthcare resources. Prices have been reduced, but whether they are now cost-effective varies from country to country.

LDL Cholesterol-How Low Can We Go?

Combinations of lipid-lowering agents can often bring LDL cholesterol down to around 40 mg/dL (1 mmol/L). Randomized controlled trials indicate that this reduces the risk of atherosclerotic vascular events with minimal adverse effects. This has raised the question of whether there is any concentration of LDL cholesterol below which further lowering is futile and/or a source of new adverse effects. This article examines several lines of evidence that lead to the conclusion that there is no known threshold below which lowering LDL cholesterol is harmful, but reduction of LDL cholesterol below 25 mg/dL may provide little if any further benefit.

Lipid-Modifying Agents, From Statins to PCSK9 Inhibitors: JACC Focus Seminar.

Mendelian randomization studies and randomized trials have conclusively demonstrated that lower low-density lipoprotein (LDL) cholesterol results in fewer cardiovascular events. This review describes key stages in the evolution of LDL cholesterol-lowering treatment. Data from over 25 cardiovascular outcome trials confirm that, within a few years, statins lower the relative risk of major atherosclerotic events by about 22% per 38.7 mg/dl (1 mmol/l) reduction in LDL cholesterol, with similar benefit across patient subgroups. Meta-analyses of these trials have established the safety of statins with regard to nonvascular mortality and cancer. Other agents available for prescription include ezetimibe and proprotein convertase subtilisin/kexin type 9 (PCSK9) inhibitors, which both reduce major atherosclerotic events in proportion to their effects on LDL cholesterol and have good safety profiles, though PCSK9 inhibitors remain costly. Investigational LDL cholesterol-lowering agents currently being tested in cardiovascular outcome studies are bempedoic acid, an adenosine triphosphate-citrate lyase inhibitor that reduces cholesterol synthesis, and inclisiran, a double-stranded small interfering ribonucleic acid that inhibits PCSK9 synthesis.

Statin Safety and Associated Adverse Events: A Scientific Statement From the American Heart Association.

One in 4 Americans >40 years of age takes a statin to reduce the risk of myocardial infarction, ischemic stroke, and other complications of atherosclerotic disease. The most effective statins produce a mean reduction in low-density lipoprotein cholesterol of 55% to 60% at the maximum dosage, and 6 of the 7 marketed statins are available in generic form, which makes them affordable for most patients. Primarily using data from randomized controlled trials, supplemented with observational data where necessary, this scientific statement provides a comprehensive review of statin safety and tolerability. The review covers the general patient population, as well as demographic subgroups, including the elderly, children, pregnant women, East Asians, and patients with specific conditions such as chronic disease of the kidney and liver, human immunodeficiency viral infection, and organ transplants. The risk of statin-induced serious muscle injury, including rhabdomyolysis, is <0.1%, and the risk of serious hepatotoxicity is ≈0.001%. The risk of statin-induced newly diagnosed diabetes mellitus is ≈0.2% per year of treatment, depending on the underlying risk of diabetes mellitus in the population studied. In patients with cerebrovascular disease, statins possibly increase the risk of hemorrhagic stroke; however, they clearly produce a greater reduction in the risk of atherothrombotic stroke and thus total stroke, as well as other cardiovascular events. There is no convincing evidence for a causal relationship between statins and cancer, cataracts, cognitive dysfunction, peripheral neuropathy, erectile dysfunction, or tendonitis. In US clinical practices, roughly 10% of patients stop taking a statin because of subjective complaints, most commonly muscle symptoms without raised creatine kinase. In contrast, in randomized clinical trials, the difference in the incidence of muscle symptoms without significantly raised creatinine kinase in statin-treated compared with placebo-treated participants is <1%, and it is even smaller (0.1%) for patients who discontinued treatment because of such muscle symptoms. This suggests that muscle symptoms are usually not caused by pharmacological effects of the statin. Restarting statin therapy in these patients can be challenging, but it is important, especially in patients at high risk of cardiovascular events, for whom prevention of these events is a priority. Overall, in patients for whom statin treatment is recommended by current guidelines, the benefits greatly outweigh the risks.

The nocebo effect in the context of statin intolerance.

The nocebo effect, the inverse of the placebo effect, is a well-established phenomenon that is under-appreciated in cardiovascular medicine. It refers to adverse events, usually purely subjective, that result from expectations of harm from a drug, placebo, other therapeutic intervention or a nonmedical situation. These expectations can be driven by many factors including the informed consent form in a clinical trial, warnings about adverse effects communicated by clinicians when prescribing a drug, and information in the media about the dangers of certain treatments. The nocebo effect is the best explanation for the high rate of muscle and other symptoms attributed to statins in observational studies and clinical practice, but not in randomized controlled trials, where muscle symptoms, and rates of discontinuation due to any adverse event, are generally similar in the statin and placebo groups. Statin-intolerant patients usually tolerate statins under double-blind conditions, indicating that the intolerance has little if any pharmacological basis. Known techniques for minimizing the nocebo effect can be applied to the prevention and management of statin intolerance.

Statin tolerability: In defence of placebo-controlled trials.

BACKGROUND: Statin intolerance is a barrier to effective lipid-lowering treatment. A significant number of patients stop prescribed statins, or can take only a reduced dose, because of adverse events attributed to the statin, and are then considered statin-intolerant. METHODS: Examination of differences between statin and placebo in withdrawal rates due to adverse events - a good measure of tolerability - in statin cardiovascular outcome trials in patients with advanced disease and complex medical histories, who may be more vulnerable to adverse effects. The arguments commonly used to dismiss safety and tolerability data in statin clinical trials are examined. RESULTS: Rates of withdrawal due to adverse events in trials in patients with advanced disease and complex medical histories are consistently similar in the statin and placebo groups. We find no support for arguments that statin cardiovascular outcome trials do not translate to clinical practice. CONCLUSIONS: Given the absence of any signal of intolerance in clinical trials, it appears that statin intolerance in the clinic is commonly due to the nocebo effect causing patients to attribute background symptoms to the statin. Consistent with this, over 90% of patients who have stopped treatment because of an adverse event can tolerate a statin if re-challenged. Consequently, new agents, including monoclonal antibodies to proprotein convertase subtilisin/kexin type 9, will be useful when added to statin therapy but should rarely be used as a statin substitute.

Simvastatin: a review.

Simvastatin is a long-established hydroxy-methylglutaryl coenzyme A (HMG-CoA) reductase inhibitor, first introduced in 1988. At the maximal recommended dose of 80 mg/day, it produces an average reduction in low-density lipoprotein cholesterol (LDL-C) of 47%, accompanied by reductions in very LDL-C, triglycerides and apolipoprotein B, and a modest increase in high-density lipoprotein cholesterol. The only important, although rare, adverse effect of simvastatin is myopathy, an effect shared by all members of the class; when severe, this can take the form of rhabdomyolysis, which may lead to acute renal failure. The mechanism of the myopathy is not understood. The risk is increased by certain concomitant drugs, including gemfibrozil and potent inhibitors of cytochrome P450 3A4. Simvastatin has been studied in two large outcome trials, the Scandinavian Simvastatin Survival Study (4S), and the Heart Protection Study (HPS), both of which demonstrated strikingly beneficial effects on a variety of cardiovascular outcomes, with minimal adverse effects. 4S was the first study with a cholesterol-lowering agent to demonstrate an unequivocal reduction in all-cause mortality (30%; p = 0.0003). HPS showed that the beneficial effects of simvastatin were obtainable in a broad array of patients with, or at high risk of, coronary heart disease (CHD) in categories previously little studied, including women, the elderly, patients with diabetes without known CHD, and, perhaps most importantly, patients with LDL-C well below the UK population average. Simvastatin has recently become available in many countries as a combination product with the cholesterol absorption inhibitor, ezetimibe. Because of its long record of safety and demonstrated ability to reduce cardiovascular risk, simvastatin has recently become available without a prescription in the UK at the 10 mg dosage level.

Effects of simvastatin on the lipid profile and attainment of low-density lipoprotein cholesterol goals when added to thiazolidinedione therapy in patients with type 2 diabetes mellitus: A multicenter, randomized, double-blind, placebo-controlled trial.

BACKGROUND: Coronary heart disease is the major cause of mortality in individuals with diabetes mellitus (DM). Given the increasingly aggressive low-density lipoprotein cholesterol (LDL-C) goals for patients with DM set by the National Cholesterol Education Program Adult Treatment Panel III and the American Diabetes Association, many patients remain above target. Treatment with thiazolidinediones (TZDs) improves glycemic control but does not lower (and may raise) LDL-C concentrations. OBJECTIVE: This study assessed the lipid-modifying efficacy and tolerability of adding the hydroxymethylglutaryl coenzyme A-reductase inhibitor simvastatin to existing TZD therapy in patients with type 2 DM. METHODS: This was a multicenter, randomized, double-blind, placebo-controlled, parallel-group trial. Patients with type 2 DM who were taking a stable dose of pioglitazone or rosiglitazone and had a glycosylated hemoglobin (HbA1c) value < or =9.0% and an LDL-C concentration > 100 mg/dL were randomized to receive simvastatin 40 mg (the recommended initial dose for patients with DM) or placebo for 24 weeks. The primary end point was the effect of treatment on LDL-C concentrations. Other lipid, lipoprotein, and safety measures were also assessed. RESULTS: Two hundred fifty-three patients (127 [50.2%] men, 126 [49.8%] women; mean age, 56 years) were randomized to treatment (123 simvastatin, 130 placebo). At the end of the study, mean LDL-C concentrations were reduced 34.)% from baseline (from 134.3 to 89.5 mg/dL) in the simvastatin group and were unchanged in the placebo group (P<0.001). Simvastatin produced significant reductions in concentrations of total cholesterol, triglycerides (TG), non-high-density lipoprotein cholesterol, and apolipoprotein (apo) B compared with placebo (all, P<0.001 ) and significant increases in concentrations of high-density lipoprotein cholesterol (HDL-C) ( P=0.002 ) and apo A-I ( P=0.006 ). In patients who had not attained target concentrations of LDL-C (<100 mg/dL), TG (<150 mg/dL), or HDL-C (>45 mg/dL) at baseline, significantly more simvastatin recipients had achieved these goals at the end of the study compared with placebo recipients (LDL-C: 67.3% vs 5.2%, respectively, P<0.001; HDL-C: 95.3% vs 83.6%, P<0.05; TG: 40.8% vs 11.0%, P<0.001 ). Simvastatin was well tolerated, and no clinically meaningful differences in the incidence of serious adverse events, treatment-related adverse events, or discontinuations due to adverse events were observed between groups. There were no significant between-group differences in glycemic control (HbA1c) or concentrations of fasting insulin, creatine phosphokinase, or hepatic transaminases. CONCLUSION: Simvastatin was an effective and generally well tolerated treatment for hyperlipidemia when used in combination with TZD therapy in this population of patients with type 2 DM.

Lovastatin and beyond: the history of the HMG-CoA reductase inhibitors.

In the 1950s and 1960s, it became apparent that elevated concentrations of plasma cholesterol were a major risk factor for the development of coronary heart disease, which led to the search for drugs that could reduce plasma cholesterol. One possibility was to reduce cholesterol biosynthesis, and the rate-limiting enzyme in the cholesterol biosynthetic pathway, 3-hydroxy-3-methyl-glutaryl-CoA (HMG-CoA) reductase, was a natural target. Here, I describe the discovery and development of lovastatin--the first approved inhibitor of HMG-CoA reductase--and the clinical trials that have provided the evidence for the ability of drugs in this class to reduce the morbidity and mortality associated with cardiovascular disease.