This article needs to be updated.(May 2018) |
Apolipoprotein A-I Milano (also ETC-216, now MDCO-216) is a naturally occurring mutated variant of the apolipoprotein A1 protein found in human HDL, the lipoprotein particle that carries cholesterol from tissues to the liver and is associated with protection against cardiovascular disease. ApoA-I Milano was first identified by Dr. Cesare Sirtori in Milan, who also demonstrated that its presence significantly reduced cardiovascular disease, even though it caused a reduction in HDL levels and an increase in triglyceride levels. [1]
The ApoA-I Milano mutation was found by University of Milan researchers after their 1974 investigation of a low HDL / high triglyceride phenotype exhibited by Valerio Dagnoli of Limone sul Garda, a small village in northern Italy. [2] : 163 Limone had only 1,000 inhabitants at the time and when blood tests were run on the entire population of the village, the mutation was found to be present in about 3.5% of the local population. [2] : 163 The mutation was traced to one man, Giovanni Pomarelli, [3] who was born in the village in 1780 and passed it on to his offspring. [4] [2] : 163 [5] It is characterised by the replacement of arginine by cysteine at position 173 (197 for UniProt). [6] The mutation is known in single nucleotide polymorphism (SNP) nomenclature as rs28931573. [7]
In the 1990s, researchers at the Cedars-Sinai Medical Center showed that injection of a synthetic version of the mutant ApoA-I into rabbits and mice could reverse vascular plaque buildup. [2] : 164
The first examination of using the mutant ApoA-I in humans was conducted through a three way collaboration between the University of Milan and the companies Pharmacia and Upjohn in 1996, focusing on treatment of atherosclerosis. [2] : 164
The ApoA-I Milano Trial, published in JAMA in 2003, [8] was the first published placebo controlled, 2 dose level, trial in humans. This was a secondary prevention trial in that those included were individuals who presented to a participating hospital with unstable angina and agreed to consent to a rigorous trial, well beyond usual clinical practice testing and treatment, testing whether this HDL protein variant, which was so effective in animals, would also work in humans. This trial was initiated by Steven Nissen of the Cleveland Clinic after prompting by Roger Newton of Esperion to examine the effects of the mutant protein using intravascular ultrasound imaging. [2] : 164 Esperion provided the protein, code named ETC-216, for the duration of the trial. [8] : 2293
Due to its potential efficacy, it was speculated that development of synthetic ApoA-I Milano might be a key factor in eradicating coronary heart disease. [9]
Esperion Therapeutics, a high tech venture capital start-up, demonstrated efficacy in both animals and humans, spending many millions of dollars over several years to conduct a single human trial which showed impressive and rapid efficacy by IVUS of coronary arteries. However, over the course of the project they produced only enough ApoA-I Milano to partially treat thirty out of the forty-five people in the randomized trial, giving them one weekly dose each for five weeks. The results of the trial were published in JAMA (November 5, 2003). [8]
Currently, no drugs based on ApoA-1 Milano are commercially available. Rights to ApoA-I Milano were acquired in 2003 by Pfizer. Clinically known as ETC-216, Pfizer did not move trials forward, probably because the complex protein is very expensive to produce and must be administered intravenously, limiting its application compared to oral medications. [10] [11]
Pfizer, after the CETP agent torcetrapib failed in a large human safety trial, decided to exit the cardiovascular market in 2008, though they continue to market Lipitor aggressively.
Esperion, divested by Pfizer in 2008, [12] is back in business and continue to work on HDL mimetic therapies. [13] The company established an agreement with TransGenRx as a protein source. [14]
Calgary-based SemBioSys Genetics Inc. was a biotechnology company that was using Safflower to develop commercial quantities of ApoA-I Milano.[ citation needed ] On October 11, 2011, SemBioSys Genetics signed a multi-product commercialization and platform collaboration agreement with Tasly Pharmaceuticals of Tianjin (China). In May 2012, SemBioSys terminated its operations and announced that Tasly had terminated their agreement. [15]
On 22 December 2009 The Medicines Company announced it had entered into an exclusive worldwide licensing agreement with Pfizer Inc. for ApoA-I Milano which it then renamed MDCO-216. [16] [17]
On the 12th of July 2010 The Medicines Company signed a pharmaceutical development and manufacturing contract with OctoPlus (Netherlands-based drug delivery and drug development company) to perform process development and clinical manufacturing of MDCO-216. [18] After a trial study failed to produce significant enough results compared to other drugs being tested, in 2016 The Medicines Company discontinued development of MDCO-216. [19]
Cardigant Medical is a Los Angeles-based biotech company that worked to commercialize ApoA-I Milano to treat various vascular diseases. As of 2021, no new trials or commercialisation have been reported, and the web domain of the company website (http://www.cardigant.com Archived 2019-06-20 at the Wayback Machine ) has expired.
High-density lipoprotein (HDL) is one of the five major groups of lipoproteins. Lipoproteins are complex particles composed of multiple proteins which transport all fat molecules (lipids) around the body within the water outside cells. They are typically composed of 80–100 proteins per particle. HDL particles enlarge while circulating in the blood, aggregating more fat molecules and transporting up to hundreds of fat molecules per particle.
Low-density lipoprotein (LDL) is one of the five major groups of lipoprotein that transport all fat molecules around the body in extracellular water. These groups, from least dense to most dense, are chylomicrons, very low-density lipoprotein (VLDL), intermediate-density lipoprotein (IDL), low-density lipoprotein (LDL) and high-density lipoprotein (HDL). LDL delivers fat molecules to cells. LDL has been associated with the progression of atherosclerosis.
Chylomicrons, also known as ultra low-density lipoproteins (ULDL), are lipoprotein particles that consist of triglycerides (85–92%), phospholipids (6–12%), cholesterol (1–3%), and proteins (1–2%). They transport dietary lipids, such as fats and cholesterol, from the intestines to other locations in the body, within the water-based solution of the bloodstream. ULDLs are one of the five major groups lipoproteins are divided into based on their density. A protein specific to chylomicrons is ApoB48.
Limone sul Garda is a town and comune in the province of Brescia, in Lombardy, at the western bank of Lake Garda.
Apolipoproteins are proteins that bind lipids to form lipoproteins. They transport lipids in blood, cerebrospinal fluid and lymph.
Hyperlipidemia is abnormally high levels of any or all lipids or lipoproteins in the blood. The term hyperlipidemia refers to the laboratory finding itself and is also used as an umbrella term covering any of various acquired or genetic disorders that result in that finding. Hyperlipidemia represents a subset of dyslipidemia and a superset of hypercholesterolemia. Hyperlipidemia is usually chronic and requires ongoing medication to control blood lipid levels.
The low-density lipoprotein receptor (LDL-R) is a mosaic protein of 839 amino acids that mediates the endocytosis of cholesterol-rich low-density lipoprotein (LDL). It is a cell-surface receptor that recognizes apolipoprotein B100 (ApoB100), which is embedded in the outer phospholipid layer of very low-density lipoprotein (VLDL), their remnants—i.e. intermediate-density lipoprotein (IDL), and LDL particles. The receptor also recognizes apolipoprotein E (ApoE) which is found in chylomicron remnants and IDL. In humans, the LDL receptor protein is encoded by the LDLR gene on chromosome 19. It belongs to the low density lipoprotein receptor gene family. It is most significantly expressed in bronchial epithelial cells and adrenal gland and cortex tissue.
Cholesteryl ester transfer protein (CETP), also called plasma lipid transfer protein, is a plasma protein that facilitates the transport of cholesteryl esters and triglycerides between the lipoproteins. It collects triglycerides from very-low-density (VLDL) or Chylomicrons and exchanges them for cholesteryl esters from high-density lipoproteins (HDL), and vice versa. Most of the time, however, CETP does a heteroexchange, trading a triglyceride for a cholesteryl ester or a cholesteryl ester for a triglyceride.
Apolipoprotein E (Apo-E) is a protein involved in the metabolism of fats in the body of mammals. A subtype is implicated in Alzheimer's disease and cardiovascular diseases. It is encoded in humans by the gene APOE.
Apolipoprotein B (ApoB) is a protein that in humans is encoded by the APOB gene. It is commonly used to detect risk of atherosclerotic cardiovascular disease.
Familial hypercholesterolemia (FH) is a genetic disorder characterized by high cholesterol levels, specifically very high levels of low-density lipoprotein cholesterol, in the blood and early cardiovascular diseases. The most common mutations diminish the number of functional LDL receptors in the liver or produce abnormal LDL receptors that never go to the cell surface to function properly. Since the underlying body biochemistry is slightly different in individuals with FH, their high cholesterol levels are less responsive to the kinds of cholesterol control methods which are usually more effective in people without FH. Nevertheless, treatment is usually effective.
Lipoprotein(a) is a low-density lipoprotein variant containing a protein called apolipoprotein(a). Genetic and epidemiological studies have identified lipoprotein(a) as a risk factor for atherosclerosis and related diseases, such as coronary heart disease and stroke.
Apolipoprotein AI(Apo-AI) is a protein that in humans is encoded by the APOA1 gene. As the major component of HDL particles, it has a specific role in lipid metabolism.
Apolipoprotein C-III also known as apo-CIII, and apolipoprotein C3, is a protein that in humans is encoded by the APOC3 gene. Apo-CIII is secreted by the liver as well as the small intestine, and is found on triglyceride-rich lipoproteins such as chylomicrons, very low density lipoprotein (VLDL), and remnant cholesterol.
Hepatic lipase (HL), also called hepatic triglyceride lipase (HTGL) or LIPC (for "lipase, hepatic"), is a form of lipase, catalyzing the hydrolysis of triacylglyceride. Hepatic lipase is coded by chromosome 15 and its gene is also often referred to as HTGL or LIPC. Hepatic lipase is expressed mainly in liver cells, known as hepatocytes, and endothelial cells of the liver. The hepatic lipase can either remain attached to the liver or can unbind from the liver endothelial cells and is free to enter the body's circulation system. When bound on the endothelial cells of the liver, it is often found bound to heparan sulfate proteoglycans (HSPG), keeping HL inactive and unable to bind to HDL (high-density lipoprotein) or IDL (intermediate-density lipoprotein). When it is free in the bloodstream, however, it is found associated with HDL to maintain it inactive. This is because the triacylglycerides in HDL serve as a substrate, but the lipoprotein contains proteins around the triacylglycerides that can prevent the triacylglycerides from being broken down by HL.
Apolipoprotein A-V is a protein that in humans is encoded by the APOA5 gene on chromosome 11. It is significantly expressed in liver. The protein encoded by this gene is an apolipoprotein and an important determinant of plasma triglyceride levels, a major risk factor for coronary artery disease. It is a component of several lipoprotein fractions including VLDL, HDL, chylomicrons. It is believed that apoA-V affects lipoprotein metabolism by interacting with LDL-R gene family receptors. Considering its association with lipoprotein levels, APOA5 is implicated in metabolic syndrome. The APOA5 gene also contains one of 27 SNPs associated with increased risk of coronary artery disease.
Apolipoprotein A-II is a protein that in humans is encoded by the APOA2 gene. It is the second most abundant protein of the high density lipoprotein particles. The protein is found in plasma as a monomer, homodimer, or heterodimer with apolipoprotein D. ApoA-II regulates many steps in HDL metabolism, and its role in coronary heart disease is unclear. Remarkably, defects in this gene may result in apolipoprotein A-II deficiency or hypercholesterolemia.
Familial dysbetalipoproteinemia or type III hyperlipoproteinemia is a condition characterized by increased total cholesterol and triglyceride levels, and decreased HDL levels.
Steven E. Nissen is an American cardiologist, researcher and patient advocate. He was chairman of cardiovascular medicine at the Cleveland Clinic, in Cleveland, Ohio.
Apabetalone is an orally available small molecule created by Resverlogix Corp. that is being evaluated in clinical trials for the treatment of atherosclerosis and associated cardiovascular disease (CVD). In the phase II clinical trial ASSURE in patients with angiographic coronary disease and low high-density lipoprotein cholesterol (HDL-C) levels, apabetalone showed no greater increase in HDL-cholesterol (HDL-c) and apolipoprotein A-I (ApoA-I) levels or incremental regression of atherosclerosis than administration of placebo, while causing a statistically significant greater incidence of elevated liver enzymes. However, pooled analysis of the effect of apabetalone in three phase II clinical trials ASSERT, ASSURE, and SUSTAIN demonstrated increases in HDL-cholesterol (HDL-c) and apolipoprotein A-I (ApoA-I) levels, as well as decreases in the incidence of major adverse cardiac events (MACE). Reduction of MACE was more profound in patients with diabetes mellitus. In a short-term study in prediabetics, favorable changes in glucose metabolism were observed in patients receiving apabetalone. An international, multicenter phase III trial, “Effect of RVX000222 on Time to Major Adverse Cardiovascular Events in High-Risk Type 2 Diabetes Mellitus Subjects with Coronary Artery Disease” (BETonMACE) commenced in October 2015. The trial is designed to determine whether apabetalone in combination with statins can decrease cardiac events compared to treatment with statins alone.