June 1, 2009
Now you see stents; soon you won't. That could be the case, at least, if bioabsorbable stents live up to their hype.
Since the first bare-metal stent was approved for use in the United States 15 years ago, stent manufacturers have been plagued by the problem of stent thrombosis. Potentially fatal, stent thrombosis occurs when a clot forms inside the stent--an adverse event for which the likelihood increases exponentially with implant duration. However, some researchers think that fully bioabsorbable stents could be the solution, especially to late stent thrombosis. The rationale: A stent can't cause clots if it no longer exists.
Recent drug-eluting stent designs have included a biodegradable polymer matrix that houses the therapeutic agent and degrades over time. Building on this concept--not to mention the success of resorbable sutures--researchers are developing drug-eluting stents that are fully metabolized and then absorbed into the body after serving their designated purpose.
Leading the charge is Abbott Vascular. About to expand into Phase II clinical trials, the company's Absorb coronary stent features a bioabsorbable polylactic acid backbone coated with an absorbable layer of everolimus drug. Although several other companies are working on the development of fully biodegradable or bioabsorbable stents, Abbott claims to be the only one that has long-term patient data. In its initial phase of clinical trials, the Absorb stent demonstrated efficacy in treating coronary artery disease and was fully absorbed by patients' bodies within two years. Furthermore, the study showed that there were zero instances of stent thrombosis two years after stent implantation and no new major adverse cardiac events.
"A fully bioabsorbable stent solves many of the challenges of metal stents. There is no metal left in the body that would impede future medical procedures--for example, if a new stent had to be inserted, there would be no metal in the artery blocking the way," notes Jonathon Hamilton, Abbott Vascular public affairs. "Also, when a metal stent is put in an artery, the stented portion remains rigid and immovable. Our two-year data in patients shows that our stent fully absorbs, and it leaves the vessel to expand and contract as if it never had a stent, allowing healthy, normal movement."
Abbott is currently hoping for a 2012 or 2013 product launch, although it has not yet specified a U.S. time frame. As with all devices, though, it's now a wait-and-see game as Abbott (and its competitors) awaits the more-definitive answers to be gained in expanded clinical trials. There's no doubt that challenges lie ahead for the Absorb, like reducing absorption time and proving its worth against existing stents. But if Abbott's bioabsorbable stent gets to market with the current statistics, it could be a game-changer for stent manufacturers and patients alike. Because, let's face it, a bioabsorbable stent is a disappearing act that has the potential to please any crowd.
Copyright ©2009 Medical Product Manufacturing News
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