Medical Device Daily Executive Editor
NEW ORLEANS — If you're the kind of person who goes to the movies and actually enjoys the six previews before the main feature, you could appreciate the early peek at the new drug-eluting stent (DES) developments provided at this year's annual meeting of the American College of Cardiology (Washington).
Against the backdrop of the ongoing debates concerning efficacy and safety issues related to stenting — and DES in particular — these previews offered a look at the DES being prepared to challenge the Taxus from Boston Scientific (Natick, Massachusetts) and the Cypher from Cordis (Miami Lakes, Florida).
The most important report came from Abbott Vascular, the vascular unit of Abbott Laboratories (Abbott Park, Illinois), which rolled out, as has frequently predicted, results of the SPIRIT III trial of its Xience V Everolimus-eluting Coronary Stent System. Based on earlier study results, Xience has been projected as the next big DES, and according to some analysts, likely to elbow both Taxus and Cypher to the background.
The trial's primary endpoint is in-segment late loss (a key measure of vessel renarrowing) at eight months, and Xience V demonstrated superiority to Taxus with a 50% reduction in late loss compared to Taxus (0.14 +/- 0.41 mm Xience V, 0.28 +/- 0.48 mm TAXUS, p superior =0.004).
That was statistical significance with a large exclamation point.
Adding another exclamation point was Xience's superiority over Taxus in its major secondary endpoint, target vessel failure (TVF) at nine months. Xience demonstrated non-inferiority to Taxus with a 21% reduction in TVF compared to Taxus (TVF being a measure of re-treatment anywhere within the target vessel and including cardiac death or heart attack.)
"Not only did the SPIRIT III trial meet its primary and major secondary endpoints, but it showed a statistically significant reduction in major adverse cardiac events, favoring Xience V," said Gregg Stone, MD, of Columbia University Medical Center and the Cardiovascular Research Foundation (both New York), principal investigator of the SPIRIT III trial, in presenting the results.
And in a not very thinly veiled reference to the current DES safety debate, Stone called Xience "an important advance" because of its "enhanced freedom from adverse event."
While the trial showed the superiority of Xience over Taxus — and Xience likely to have quick uptake, once approved — Boston Scientific nevertheless mined good news from the SPIRIT III report, since it has a deal with Abbott for marketing rights to Xience.
Charles Rudnick, director of corporate communications for Boston Scientific, noted that half of the Xience products will be packaged and sold by it as Promus (the result of a distribution agreement developed last year).
The margin on sales won't be as great for Boston Scientific as for Abbott, Rudnick told Medical Device Daily, but he said that Boston Scientific will have a marketing edge by leveraging its position as having two DES products approved in the U.S., as well as overseas.
Less optimistic about that was Mark Richter, a device and diagnostics analyst for Jefferies & Company (New York). He wrote in a report that SPIRIT III doesn't offer "a death sentence for Boston's DES franchise" but "will hurt its market share in the near term and create volatility" in its stock.
Lawrence Biegelsen, analyst with Prudential Equity Group (New York), reported that he expects Abbott to file for Xience FDA approval in the 1Q08, with potential market launch the following quarter.
"[W]e are raising our peak market share estimate for combined Xience-V/Promus sales to 55% from 35% in the US and Europe/ROW," Biegelsen wrote in his report.
The Xience V system uses the drug everolimus, which Abbott says "has been shown to reduce tissue proliferation in the coronary vessels following stent implantation and is based upon the highly deliverable and proven Multi-Link Vision coronary stent platform." Xience was launched in Europe and Asia Pacific in 2006.
Abbott also provided a preview-type look at another group of stents poised to come on line — though more slowly and perhaps requiring a time line of three to four or more years — that of stents that are absorbed and completely disappear from the body.
It reported positive results from ABSORB, the company calling the study the "first clinical trial evaluating the overall safety and performance of a fully bioabsorbable drug-eluting stent platform for the treatment of coronary artery disease."
Six-month results from the first 30 patients in the trial demonstrated no stent thrombosis and a low (3.3%) "hierarchical" rate of ischemia-driven major adverse cardiac events (MACE), such as heart attack or repeat intervention.
"The encouraging results from the first 30 patients of ABSORB suggest that drug-eluting bioabsorbable stent technologies may be a promising future therapy option for physicians treating patients with heart disease," said Patrick Serruys, MD, PhD, professor of interventional cardiology at the Thoraxcentre, Erasmus University Hospital (Rotterdam, the Netherlands), co-principal investigator of the study.
He called that complete absorption "exciting," a view shared by many since that ability leaves no stent or polymer coating artifact to irritate vascular tissue.
The single major adverse event reported was a non-Q-wave myocardial infarction, and the patient underwent a repeat intervention at the site of the original procedure, resulting in the overall target lesion revascularization rate of 3.3%.
The company said that these results confirm a treatment effect of everolimus in the bioabsorbable stent similar to that seen in Abbott's studies of metallic DES devices, with everolimus actively inhibiting tissue growth into the artery.
The trial also showed a device placement success rate of 93.5%.
Abbott's everolimus-eluting bioabsorbable stent is made of polylactic acid, a biocompatible material commonly used in medical implants such as dissolvable sutures.
"Based on these encouraging safety results, Abbott will continue to advance this technology by enrolling the next cohort of patients in the ABSORB study in Europe and New Zealand," said John Capek, PhD, senior VP, Abbott Vascular.
ABSORB is a prospective, non-randomized (open label) study enrolling up to 60 patients in Belgium, Denmark, France, New Zealand, Poland and the Netherlands.