A Medical Device Daily

Conor Medsystems (Menlo Park, California) reported this week that it has received FDA approval of an investigational device exemption (IDE) to begin its Cobalt chromium STent with Antiproliferative for Restenosis (COSTAR II) pivotal clinical trial.

The company said it expects the data from the trial to support U.S. regulatory approval of its CoStar cobalt chromium paclitaxel drug-eluting stent (DES) for the treatment of restenosis.

COSTAR II proposes enrollment of about 1,700 patients at up to 70 U.S. sites and 15 international sites. The trial will be a randomized, single-blind, non-inferiority study comparing Conor's CoStar stent against the Taxus Express2 drug-eluting stent made by Boston Scientific (Natick, Massachusetts) in the treatment of de novo lesions in patients with single or multi-vessel coronary artery disease. Patients will be asymmetrically randomized between CoStar and the control stent, with clinical follow-up at 30 days and eight months. In addition, a 350-patient subset will under-go follow-up angiography at nine months.

Conor said that the FDA's conditional approval of the IDE requires the company to provide additional information to the agency. The study is expected to begin by mid-year, with enrollment expected to take an estimated six to nine months for completion.

Azin Parhizgar, PhD, chief operating officer of Conor, called the approval a "significant milestone."

The company's expectation is to file an FDA premarket approval application for the stent in the second half of 2006. It noted that no second pivotal study is needed but Conor will be conducting a direct stenting registry.

Parhizgar said that the company thus far has developed positive safety and efficacy data on the CoStar stent, "most recently from the six-month follow-up data from our EuroSTAR trial. We believe these results are due to our stent's unique drug reservoir design, which allows for greater control over the direction, rate and duration of drug release. In the U.S. trial, we will use the low dose of 10 mcg of paclitaxel per 17 mm stent with a bioresorbable polymer. This system is designed to completely release the drug without any permanent residual polymers remaining at the target site."

The primary endpoint for the study will be major adverse cardiac events at eight months, defined as a composite of target vessel revascularization (TVR), myocardial infarction and cardiac-related death.

Other endpoints include target lesion revascularization (TLR), binary restenosis, and in-segment and in-stent late loss as measured by angiography.

The trial will include a registry for direct stenting. Principal investigators involved in the study include Dean Kereiakes, MD, of the Ohio Heart Health Center (Cincinnati); Mitchell Krucoff, MD, of Duke University Medical Center (Durham, North Carolina); and Patrick Serruys, MD, PhD, of the Thoraxcenter-Erasmus University (Rotterdam, the Netherlands).

Earlier this month, Conor reported positive six-month follow-up data from the first arm of the company's Euro-STAR study evaluating the CoStar stent. A total of 176 lesions were treated in 145 patients using the CoStar stent formulated to deliver a dose of 10 mcg of paclitaxel (per 17 mm stent) over about 30 days, based on in vitro measurements. The in-stent binary restenosis rate was 3.4% and the in-stent late loss was 0.26 millimeters. The in-segment binary restenosis rate was 4.7% and the in-segment late loss was 0.07 millimeters. The TLR rate was 1.7% and the MACE rate was 4.8%.

Data from the EuroSTAR trial was used to support the company's CE mark application, filed earlier this quarter for regulatory approval of the CoStar stent in the European Community. Conor said it anticipates receiving regulatory approval in Europe in the second half of this year.

A limited market release of the CoStar stent began this month in India with the company's South Asian distribution partner, Interventional Technologies.