These stents are superior to the older metal-only stents in that the drug released by the polymer is aimed at preventing the vascular vessel from reclogging. But recent research suggests that one or more components of these stents are causing inflammation and thrombosis in some patients. Research has yet to point out the culprit; the stent itself, the polymer, or the drug.
Recently, the FDA and other organizations have concluded that while thrombosis does occur from the use of these stents, the risk is small enough to allow its continued use. The debates, however, have motivated various companies, including JNJ and Boston Scientific, to bring to the market a new class of drug-eluted stent that minimizes the degree or incidence of clotting in patients.
Endeavor, which is developed by Medtronic (NYSE:MDT), could be the first on the U.S. market, as the company filed with the FDA back in November, and could receive approval in the second half of 2007. Endeavor uses a type of polymer that research has shown to reduce inflammation and induce healing of tissue.
Abbot Laboratories (NYSE:ABT) has filed for FDA approval of Xience. This stent uses a very thin film of polymer that could cause less inflammation. The stent could receive marketing approval in the U.S. by early next year.
Johnson & Johnson acquired Conor Medsystems recently to get its hands on CoStar, a new stent that reduces inflammation by reducing the contact time of the polymer and drug with the artery. The polyer and the drug dissolve within six months, leaving the bare metal stent.
All three stents, the Endeavor, Xience, and CoStar are already on the market in select international nations.
Boston Scientific's next generation stent, Taxus Liberte, uses the same polymer and drug as the original Taxus, but is designed to be thinner, and could produce less irritation and inflammation. The approval of Taxus Liberte is on hold, however, until the FDA lifts a warning letter it attached to the stent's submission papers. The company hopes the letter is lifted soon, as investors and Wall Street have pounded the stock, losing half of its value in just two years.
Biosensors International's BioMatrix is expected to receive marketing approval from the European Union soon, and enter U.S. trials possibly later this year. The stent uses a polymer that also dissolves over time, and a new, safer drug.
Researchers and doctors are excited about the promise of this new class of stents, but caution that more data is needed. Medtronic is the only company that has a large data set on its stent, comprising 1300 patients over two years. By contrast, Abbott has a two year study on 27 patients, and data for one year on 300 patients.