GAITHERSBURG, MD. – A Food and Drug Administration advisory panel on Oct. 13 voted 11-0 that the benefits of a drug-eluting stent outweighed its risks as a treatment for patients with symptomatic atherosclerotic stenosis of the femoropopliteal arteries.
The FDA’s Circulatory System Devices Panel also unanimously voted that the available data provided "reasonable assurance" that the Zilver PTX drug-eluting stent (DES) was safe and effective for the proposed indication. The panel did not specifically vote on whether to recommend approval.
The Zilver PTX stent is a self-expanding, nitinol stent coated with paclitaxel, which is the active ingredient in the chemotherapy treatment Taxol and in the FDA-approved Taxus coronary stent. Its delivery system is the same as the one used with the Zilver vascular stent, a bare-metal stent (BMS) that is FDA approved for use in iliac arteries.
The Zilver PTX stent’s manufacturer, Cook Medical Inc., has proposed that the Zilver PTX be approved for "improving luminal diameter for the treatment of de novo or restenotic symptomatic lesions in vascular disease of the above-the-knee femoropopliteal arteries," with reference vessel diameters from 4 mm to 9 mm and total lesion lengths measuring up to 140 mm/limb and 280 mm/patient. The same stent has been approved for use in femoropopliteal arteries in Europe since 2009, according to Cook.
If approved, it will be the first drug-eluting stent approved in the United States for treating femoropopliteal arteries.
The pivotal study, a randomized, controlled open-label trial in the United States, Japan, and Germany, enrolled almost 500 patients (mean age 68 years) with up to two stenotic or occluded atherosclerotic lesions of above-the knee femoropopliteal arteries (up to one in each limb), measuring a maximum of 14 cm or less in length, and randomized then to treatment with the Zilver PTX stent (240 patients) or percutaneous transluminal angioplasty (238). Patients whose angioplasty results were suboptimal (120) were randomized a second time to treatment with the Zilver bare metal stent (56 patients) or the Zilver PTX stent (64). Patients were treated with clopidogrel, which was started either before or during the procedure (patients in Japan received ticlopidine), and for 60 days after the procedure, with aspirin indefinitely.
At 12 months, the patency rate was 83% among those treated with the Zilver PTX stent, compared with 33% of those who had angioplasty. Among those who had been randomized a second time, the patency rate at 12 months was 90% among those who had the Zilver PTX stent, compared with 73% of those who received the Zilver BMS.
The primary safety end point was "event-free survival" at 12 months defined as "freedom" from death, target lesion revascularization, worsening symptoms, or ischemia of the target limb requiring surgery of the target vessel – which was 84% among those treated with angioplasty, compared with 90% of those treated with the Zilver PTX stent.
The FDA usually follows the recommendations of its advisory panels. Panel members have been cleared of potential conflicts before the meeting.