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New Drug-Eluting Stents Under Study

New Drug-Eluting Stents Under Study NEW ORLEANS—The first generation of drug-eluting stents has come under fire in recent months for inappropriate use in some patients with stable coronary artery disease and for possibly promoting late-event thrombosis. But stents remain essential tools for cardiologists treating patients with a variety of coronary problems, and researchers and manufacturers continue to design and test new versions, with the aim of improving outcomes while diminishing adverse events. Results from an array of drug-eluting stent trials were presented here in March at the annual meeting of the American College of Cardiology. Among the new types of stents discussed were those with a thin metal platform using a new drug; a biodegradable stent that may solve the late-event thrombosis concern; a stent using two drugs; and a stent that captures endothelial progenitor cells (EPCs). This bioabsorbable stent is one of a number of new stents that are being studied to determine if they can prevent restenosis while avoiding late-event thrombosis. (Photo credit: Abbott) In a comparison trial involving 1002 patients at 65 US sites, an everolimus-eluting stent resulted in significantly less late lumen loss at 9 months than did the paclitaxel-eluting stent (0.14 mm vs 0.28 mm). Gregg W. Stone, MD, of Lenox Hill Hospital, New York City, and lead investigator of the SPIRIT III trial, said target vessel failure (myocardial infarction, cardiac death, or revascularization) was 7.2% for the Xience everolimus stent (Abbott Laboratories, Abbott Park, Ill) compared with 9.0% for the Taxus paclitaxel stent(Boston Scientific Corp, Natick, Mass). The trial design and sample size suggest equivalence in treatment of target vessel failure between the 2 stents (the investigators said significance was established for noninferiority but not for superiority of the everolimus-eluting stent compared with the paclitaxel-eluting stent). SPIRIT III was intended to add to the body of evidence Abbott Laboratories will bring to the US Food and Drug Administration when it seeks approval of Xience in the states. Ted E. Feldman, MD, professor of medicine at Northwestern University Feinberg School of Medicine, in Chicago and a past president of the Society of Society for Cardiac Angiography and Interventions, called SPIRIT III “evolutionary vs revolutionary,” in that it tested a conventional stent coated with a drug whose molecular structure is slightly different from current medicines found on drug-eluting stents. The disappearing stent The disappearing stent More intriguing, said Feldman, are the findings from the ABSORB trial, the first human trial of a bioabsorbable everolimus-eluting stent, manufactured by Abbott Laboratories. The rationale behind a bioabsorbable stent centered on the two adverse outcomes associated with stenting, in-stent restenosis for bare metal and late-term thrombosis for drug-eluting stents. A bioabsorbable stent should be able to deliver a drug to prevent restenosis while the artery fully absorbs and slowly metabolizes it. This leaves a patent vessel in its place with no stent remaining to cause thrombosis. In contrast, scar tissue tends to form around a bare metal stent, which shields it from causing thrombosis but may lead to restenosis. The disappearing stent In this trial, conducted by investigators from Erasmus Medical Center in Rotterdam, the Netherlands, 30 patients at 4 sites in Europe and New Zealand received a stent composed of a biodegradable material (a polyester derived from lactic acid) for treatment of a single coronary artery lesion. At 30 days, device success was 93.5%, while ease of deployment and safety was 100%, with no patients experiencing a major adverse coronary event or stent thrombosis. At 180 days, major adverse coronary events were at 3.3% and there were no cases of stent thrombosis. However, the restenosis rate was 11.5%, which was attributed to unexpected shrinkage of the implanted stent. Feldman said the 93.5% success rate at 30 days was acceptable for placement of a first-generation device and that a 98% success rate is the norm in inserting current stents. The disappearing stent Patrick Serruys, MD, PhD, a co–principal investigator of the ABSORB trial, said the stent was being redesigned to address the shrinkage issue and noted that this trial represented an early first step in bringing biodegradable stents into clinical practice. The disappearing stent Feldman said that given the safety data on the biodegradable stent, he would have no reservations in enrolling patients in any subsequent trials of this stent. “The consequences of a stent going away are not known by anyone, but in the end you're left with your own artery and no foreign body. So it's attractive to be in this kind of trial,” he said. Drug combo fails Drug combo fails In another approach to avoiding restenosis and late-event thrombosis, researchers from Deutsches Herzzentrum of Technische Universität, in Munich, Germany, studied 502 patients treated with a stent containing two drugs—rapamycin and estradiol. The hope was that adding estradiol, a hormone that is associated with promoting endothelial growth, would encourage these smooth cells to proliferate and quickly cover the stent, thus helping to avoid formation of scar tissue that can begin the restenosis process. Unfortunately, 6-month and 12-month follow-up showed no trends toward superiority of the dual-drug stent. Drug combo fails “Estradiol worked with stents in animals, but it didn't work in a human trial, so is the concept forever gone?” Feldman asked. “The answer is ‘maybe.’ It was used [in the trial] with rapamycin and a polymer, so it might work with a different drug and polymer—but that would require a different study.” Drug combo fails Another approach focusing on promoting endothelial growth to avoid in-stent restenosis came from researchers from the Netherlands. In a single-center registry study of 87 patients, the researchers implanted the EPC-capturing stent (OrbusNeich, Hong Kong). This device is coated with an antibody (CD34+) that attracts EPCs, which results in functional endothelial tissue layering the artery, thus accelerating healing and possibly reducing in-stent restenosis. At 6 months, the researchers said the stent had shown excellent procedural success with target vessel revascularization at 3.7%. Feldman said he expected to see a more rigorous randomized trial of the EPC-capturing stent in the near future. http://www.deepdyve.com/assets/images/DeepDyve-Logo-lg.png JAMA American Medical Association

New Drug-Eluting Stents Under Study

Mitka, Mike
JAMA , Volume 297 (19) – May 16, 2007
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Publisher
American Medical Association
Copyright
Copyright © 2007 American Medical Association. All Rights Reserved.
ISSN
0098-7484
eISSN
1538-3598
DOI
10.1001/jama.297.19.2064
Publisher site
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Abstract

NEW ORLEANS—The first generation of drug-eluting stents has come under fire in recent months for inappropriate use in some patients with stable coronary artery disease and for possibly promoting late-event thrombosis. But stents remain essential tools for cardiologists treating patients with a variety of coronary problems, and researchers and manufacturers continue to design and test new versions, with the aim of improving outcomes while diminishing adverse events. Results from an array of drug-eluting stent trials were presented here in March at the annual meeting of the American College of Cardiology. Among the new types of stents discussed were those with a thin metal platform using a new drug; a biodegradable stent that may solve the late-event thrombosis concern; a stent using two drugs; and a stent that captures endothelial progenitor cells (EPCs). This bioabsorbable stent is one of a number of new stents that are being studied to determine if they can prevent restenosis while avoiding late-event thrombosis. (Photo credit: Abbott) In a comparison trial involving 1002 patients at 65 US sites, an everolimus-eluting stent resulted in significantly less late lumen loss at 9 months than did the paclitaxel-eluting stent (0.14 mm vs 0.28 mm). Gregg W. Stone, MD, of Lenox Hill Hospital, New York City, and lead investigator of the SPIRIT III trial, said target vessel failure (myocardial infarction, cardiac death, or revascularization) was 7.2% for the Xience everolimus stent (Abbott Laboratories, Abbott Park, Ill) compared with 9.0% for the Taxus paclitaxel stent(Boston Scientific Corp, Natick, Mass). The trial design and sample size suggest equivalence in treatment of target vessel failure between the 2 stents (the investigators said significance was established for noninferiority but not for superiority of the everolimus-eluting stent compared with the paclitaxel-eluting stent). SPIRIT III was intended to add to the body of evidence Abbott Laboratories will bring to the US Food and Drug Administration when it seeks approval of Xience in the states. Ted E. Feldman, MD, professor of medicine at Northwestern University Feinberg School of Medicine, in Chicago and a past president of the Society of Society for Cardiac Angiography and Interventions, called SPIRIT III “evolutionary vs revolutionary,” in that it tested a conventional stent coated with a drug whose molecular structure is slightly different from current medicines found on drug-eluting stents. The disappearing stent The disappearing stent More intriguing, said Feldman, are the findings from the ABSORB trial, the first human trial of a bioabsorbable everolimus-eluting stent, manufactured by Abbott Laboratories. The rationale behind a bioabsorbable stent centered on the two adverse outcomes associated with stenting, in-stent restenosis for bare metal and late-term thrombosis for drug-eluting stents. A bioabsorbable stent should be able to deliver a drug to prevent restenosis while the artery fully absorbs and slowly metabolizes it. This leaves a patent vessel in its place with no stent remaining to cause thrombosis. In contrast, scar tissue tends to form around a bare metal stent, which shields it from causing thrombosis but may lead to restenosis. The disappearing stent In this trial, conducted by investigators from Erasmus Medical Center in Rotterdam, the Netherlands, 30 patients at 4 sites in Europe and New Zealand received a stent composed of a biodegradable material (a polyester derived from lactic acid) for treatment of a single coronary artery lesion. At 30 days, device success was 93.5%, while ease of deployment and safety was 100%, with no patients experiencing a major adverse coronary event or stent thrombosis. At 180 days, major adverse coronary events were at 3.3% and there were no cases of stent thrombosis. However, the restenosis rate was 11.5%, which was attributed to unexpected shrinkage of the implanted stent. Feldman said the 93.5% success rate at 30 days was acceptable for placement of a first-generation device and that a 98% success rate is the norm in inserting current stents. The disappearing stent Patrick Serruys, MD, PhD, a co–principal investigator of the ABSORB trial, said the stent was being redesigned to address the shrinkage issue and noted that this trial represented an early first step in bringing biodegradable stents into clinical practice. The disappearing stent Feldman said that given the safety data on the biodegradable stent, he would have no reservations in enrolling patients in any subsequent trials of this stent. “The consequences of a stent going away are not known by anyone, but in the end you're left with your own artery and no foreign body. So it's attractive to be in this kind of trial,” he said. Drug combo fails Drug combo fails In another approach to avoiding restenosis and late-event thrombosis, researchers from Deutsches Herzzentrum of Technische Universität, in Munich, Germany, studied 502 patients treated with a stent containing two drugs—rapamycin and estradiol. The hope was that adding estradiol, a hormone that is associated with promoting endothelial growth, would encourage these smooth cells to proliferate and quickly cover the stent, thus helping to avoid formation of scar tissue that can begin the restenosis process. Unfortunately, 6-month and 12-month follow-up showed no trends toward superiority of the dual-drug stent. Drug combo fails “Estradiol worked with stents in animals, but it didn't work in a human trial, so is the concept forever gone?” Feldman asked. “The answer is ‘maybe.’ It was used [in the trial] with rapamycin and a polymer, so it might work with a different drug and polymer—but that would require a different study.” Drug combo fails Another approach focusing on promoting endothelial growth to avoid in-stent restenosis came from researchers from the Netherlands. In a single-center registry study of 87 patients, the researchers implanted the EPC-capturing stent (OrbusNeich, Hong Kong). This device is coated with an antibody (CD34+) that attracts EPCs, which results in functional endothelial tissue layering the artery, thus accelerating healing and possibly reducing in-stent restenosis. At 6 months, the researchers said the stent had shown excellent procedural success with target vessel revascularization at 3.7%. Feldman said he expected to see a more rigorous randomized trial of the EPC-capturing stent in the near future.

Journal

JAMA – American Medical Association

Published: May 16, 2007

Keywords: stents,drug-eluting stents

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