BIOFREEDOM: Polymer-Free Biolimus Stent Reduces Late Lumen Loss Compared With Taxus

September 28, 2010

September 27, 2010 (Washington, DC) — A polymer-free drug-eluting stent performed as well as a first-generation paclitaxel-eluting stent in a head-to-head comparison in patients with coronary artery disease, according to the results of a new study. After one year, the novel biolimus A9-eluting stent was statistically noninferior to the paclitaxel-eluting stent in terms of in-stent late lumen loss and trending toward superiority, report investigators.

Presenting the results of the first-in-human BIOFREEDOM study during the late-breaking clinical-trials session at TCT 2010, Dr Eberhard Grube (International Heart Center, Essen, Germany) said the surface of the stent has been modified to hold the limus drug in the stent's abluminal surface structures, "the hypothesis being that the polymer-free drug release might reduce late events caused by a polymer stent coating."

The hope, he continued, is that the polymer-free biolimus A9-eluting stent can reduce late adverse events attributed to the polymer, such as stent thrombosis, and potentially reduce the duration of dual antiplatelet therapy.


To test the hypothesis, the researchers randomized two cohorts to receive one of two biolimus-eluting stents that contained a standard dose of the limus drug or a lower dose, as well as to treatment with the paclitaxel-eluting stent (Taxus Liberté, Boston Scientific). Of these 182 patients within the two cohorts, 75 patients were followed for four months (cohort 1) before undergoing follow-up angiography and 107 patients were followed for 12 months (cohort 2) before undergoing angiography. All patients had symptomatic ischemic heart disease, with diseased native coronary arteries ranging in diameter from >2.25 mm to <3.0 mm.

Presenting the 12-month data last week, Grube reported that in-stent late lumen loss was statistically equivalent in all three groups: 0.17 mm among patients treated with the standard limus dose (15.6 µg/per mm of stent length), 0.22 mm for the low-dose biolimus A9-eluting arm (7.8 µg/per mm of stent length), and 0.35 mm for those treated with the Taxus stent (p=0.001 for noninferiority). There was no difference in 12-month rates of major adverse cardiac events (MACE), a composite that included all-cause mortality, emergent bypass surgery, or target lesion revascularization, and no reported cases of early or late stent thrombosis.

Speaking during the late-breaking clinical-trials panel discussion, Dr John Ormiston (Auckland City Hospital, New Zealand) said the hope with the polymer-free drug-eluting stent is a reduction in stent thrombosis, shorter duration of dual antiplatelet platelet, and a reduction in risk when dual therapy is stopped. He noted that the limus drug was already shown to be effective in the Limus Eluted from a Durable versus Erodable Stent Coating (LEADERS) trial. In that trial, the novel stent platform included a sirolimus analog eluted from a biodegradable polymer and was shown to be noninferior to the permanent-polymer sirolimus-eluting stent in terms of the primary end point of cardiac death, MI, and target-vessel revascularization.

Dr David Kandzari (Piedmont Heart Institute, Atlanta, GA) called the polymer-free biolimus A9-eluting stent a third-generation stent, coming as it did after the stent with biodegradable polymer and after the earlier first-generation stents. Important next steps, he said, will be the reproducibility of the stent's performance in larger populations and the durability of the results over time. Both Kandzari and Ormiston noted that late lumen loss basically doubled from four months--when cohort 1 underwent coronary angiography--to one year. At four months, in this cohort of 75 patients, late lumen loss in the standard- and low-dose stent arms was 0.08 mm and 0.12 mm, respectively.

"It's noticeable that the directional changes, roughly a doubling of late loss, are observed independent of dose in this particular study," said Kandzari.

Grube reports consulting for Boston Scientific, Cordis, Abbott Vascular, Mitralign, Claret, Embrella, Biosensors, Medtronic, and CoreValve and holding stock in Direct Flow Medical, Mitralign, Claret, Embrella, Biosensors, Medtronic, CoreValve, and Sadra Medical. Kandzari reports research support from Cordis and consulting fees from Cordis, Abbott Vascular, AngioScore, and Medtronic. Ormiston reports consulting for Boston Scientific and Abbott Vascular.