Drug-Eluting Stents

Frost & Sullivan market estimates found that the global coronary stent market was valued at almost $8.9 billion in 2017. Learn more about several innovative companies in this space.

Coronary artery diseases (CADs) are a family of heart conditions that include myocardial infarction, stable and unstable angina and sudden cardiac death. The underlying cause of CADs is the accumulation of cholesterol, calcium and other minerals along the internal walls of coronary arteries. Over time, these substances solidify and form plaque along the artery walls, reducing vessel diameter and blood flow—a condition known as atherosclerosis. Atherosclerosis of the coronary artery that supplies blood to the heart results in a cardiac stroke, damaging the heart muscles (myocardial infarction). This manifests as chest pain and discomfort—two symptoms of a heart attack. CAD occurrence is increasing because of unhealthy lifestyles led by a lack of exercise and consumption of fatty food. The U.S. Centers for Disease Control and Prevention (CDC) estimates more than 380,000 adult Americans die every year from conditions stemming from CADs. 

Percutaneous transluminal angioplasty, or simply angioplasty, is a minimally invasive procedure that widens the narrowed arteries. Angioplasty involves inserting a thin, flexible catheter through a patient’s venous network and to the heart to manually expand the blocked artery. This is usually done with the help of a balloon catheter, which pushes the walls out to restore patency to the occluded vessel. An adjunct procedure may be performed along with this to make reocclusion less likely: a stent is placed at the site of the lesion to prop up the artery and prevent the walls from constricting again. 

Stents have been in use for decades and are viewed as a standard treatment option for these conditions. However, this procedure has disadvantages. The stent—usually made of biocompatible metals such as clinical-grade stainless steel or a chromium alloy—can contribute to fibrous connective tissue formation in situ, a condition known as fibrosis. While fibrosis itself is not pathological, it could lead to constriction of the blood vessels again. Also, bare metal stents (BMS) lead to clotting of the blood, or thrombosis. Together, thrombosis and fibrosis cause restenosis, or the recurrence of constriction. 

In order to prevent this, BMS platforms are coated with an anti-proliferative drug that can prevent cellular infiltration. The drug is either stored in reservoirs in the stent structure or coated along the outer wall of the stent for easy and effective release, hence the name drug-eluting stents (DES). The drug, usually a derivative of the limus family of drugs, acts on the proliferating cells by disrupting their metabolic pathways and inhibiting their cellular cycles. The anti-cancer drugs (including sirolimus, everolimus and zotarolimus) are designed to inhibit cells’ mitotic cycle and prevent them from dividing indefinitely. By curbing tissue growth and scar formation, they reduce the risk of restenosis. 

Frost & Sullivan market estimates found that the global coronary stent market was valued at almost $8.9 billion in 2017. Of this, the DES segment is the largest, amounting to 55% ($4.8 billion) as shown in Exhibit 1. Frost & Sullivan has also identified several innovative companies in this space. 

Medtronic (Minneapolis, Minn.)

In February 2018, global medical device major Medtronic announced U.S. Food and Drug Administration (FDA) approval for the smallest variant of its flagship DES product, Resolute Onyx. Sizes now range from 2 to 5 mm.  The stent backbone is made of a platinum-iridium core, ensconced in a cobalt alloy shell; the stent elutes the drug zotarolimus over a period of 30 days.

OrbusNeich (Hong Kong)

OrbusNeich’s Combo Dual Therapy Stent is designed so that both the internal and external surfaces are coated with a special biopharmaceutical layer. The internal surface is coated with a specific antibody known as anti-CD34, which attracts and captures certain endothelial progenitor cells—in other words, it promotes blood circulation in the lesioned area. The external surface, which faces the vessel wall, is coated with sirolimus, known for its anti-restenotic properties. The dual therapy effectively prevents restenosis and promotes the growth of endothelial cells to strengthen the damaged artery.

Boston Scientific (Boston, Mass.)

The Promus Premier from Boston Scientific is an everolimus-eluting stent built on a platinum-chromium platform. The alloy framework offers improved visualization during implantation, better flexibility, and high radial strength—all important attributes when a stent is being deployed through tortuous vessels and in sites with high stenosis. Promus Premier is FDA-approved, including for high-risk patients with diabetes mellitus.

The Road Ahead

Having a metallic structure left behind after healing may not be ideal when there is a bioabsorbable option available. Demand for DES is still strong; the market threat from bioabsorbable stent platforms that dissolve over time has yet to be determined. Boston Scientific, Elixir Medical (Sunnyvale, Calif.) and Abbott Vascular (Lake Bluff, Ill.) have developed a hybrid drug-eluting/bioabsorbable stent. While Elixir’s DESolve range of drug-eluting bioabsorbable scaffolds is available in Europe, Abbott announced a discontinuation of its bioabsorbable product, Absorb GT1, in September 2017. As growing clinical evidence boosts the confidence of regulatory agencies, physicians and patients, it is expected that the market will continue favoring DES over first-generation BMS products and the yet-to-be-accepted bioabsorbable products. 

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