|Drug-Eluting Coronary Stents: An Opening for Cypher?|
At this year's annual meeting of the American College of Cardiology (ACC; Bethesda, MD), the confluence of three major comparative studies of drug-eluting coronary stents led industry observers to dub the event the great American stent shoot-out. Initial reports suggested that no clear-cut winner had emerged from the shoot-out between rivals Boston Scientific Corp. (Natick, MA) and Cordis Corp. (Miami Lakes, FL), a Johnson & Johnson company—the only two companies with FDA approval to market drug-eluting stents on the U.S. market. But later postings on the three studies presented at the recently concluded conference in Orlando, FL, were generally perceived to give one of the stents a definite edge.
In the main event, a Cordis-sponsored randomized study of 1386 patients matched for age, gender, coronary history, and other variables, put Boston Scientific's Taxus and Cordis' Cypher stents in a head-to-head comparison. The primary performance metric of the so-called Reality study was the degree to which each stent prevented restenosis, or reclogging of the treated artery.
The findings revealed that Taxus and Cypher performed equally well and were deemed “substantially equivalent” in preventing restenosis. In addition, the study indicated that both stents were “equally deliverable”—an area of concern in which the Taxus stent has benefited from the widely held perception among cardiovascular surgeons that its delivery system is superior to that of the Cypher stent.
Early reports from ACC, in both the medtech industry and general business press, heralded the findings as a kind of stent standoff. The reports typically noted that the Reality study failed to deliver the endpoint results sought by Cordis, which had hoped to demonstrate the superiority of its Cypher stent over Taxus.
But several hours later, when additional results from Reality were analyzed in conjunction with two other comparative studies of both stents, Cypher appeared to gain a clear edge over the rival Taxus stent.
Marie-Claude Morice, MD, lead investigator for the Reality study, reported that the incidence of blood clots at the stent site were 78% lower with the Cypher stent than with Taxus. “The difference in the rate of stent thrombosis raises concerns and demands further investigation,” said Morice. Additionally, she reported that Cypher patients had significantly less “late-loss” or tissue ingrowth into the stent and significantly larger vessel openings inside the stent at eight months follow-up—factors that determine the amount of blood that is delivered to the heart muscle. The results of the Reality study, she said, clearly demonstrated Cypher's superiority.
A Swiss research team, reporting on the noncommercially funded Sirtax study of 1005 patients, found that Cypher patients experienced significantly fewer adverse events, including heart attack, the need for repeat revascularization procedures, or death. Among patients in the Cypher sample of the study, 6.2% experienced such an event, compared with 11% of the Taxus patients. Almost all of the reported adverse advents were in the repeat procedure category. The Sirtax study included more patients with serious coronary disease and had no limit on the number or length of lesions or the number of vessels involved.
An additional smaller study with just 250 patients suggested that the Cordis stent might be more effective with certain high-risk populations such as diabetics, whose arteries are generally more susceptible to reclogging than those of nondiabetics. The Isar-Diabetes study found that restenosis, which the investigators defined as a renarrowing of the stented vessel by at least 50%, occurred in 17% of patients with a Taxus stent, compared with 6.9% of those implanted with Cypher.
Many researchers cautioned against reading too much into the findings and called for additional clinical studies. But the lead investigator on the Sirtax study, Stephan Windecker, MD, chief of the cardiac catheterization lab at University Hospital in Bern, Switzerland, described the Cypher stent as “superior.” He indicated that his hospital, which currently alternates between the two stents, will likely switch over to Cypher based on the findings.
LaViolette: No concessions.
In a conference call with analysts, Paul LaViolette, chief operating officer for Boston Scientific disputed any assessment that gave an advantage to Cypher over Taxus. He emphasized the finding of “substantial equivalence” reported in Cordis's own Reality study. “We were particularly pleased to see that Reality reaffirmed the safety of the Taxus stent system. As highlighted in the ACC presentation, there were ‘no significant differences' in safety endpoints between the Cypher and Taxus systems.”
Commenting on the ACC studies, Dennis Donohoe, MD, vice president for worldwide regulatory and clinical affairs at Cordis, said “There is a growing body of meaningful and predictive data to examine about the Cypher stent . . . and time and again, researchers continue to find that the Cypher offers benefit for many types of patients and lesions in the near- and long-term.”