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Conor Medsystems Presents Positive Results from PISCES Drug Eluting Stent Trial

Menlo Park, California, May 25, 2004 - Conor Medsystems, Inc., today presented acute and follow-up data from its PISCES (Paclitaxel In-Stent Controlled Elution Study) clinical trial at the EuroPCR meeting in Paris, a leading international conference in interventional cardiology. Results from PISCES support the safety of Conor's stents and, importantly, demonstrated in one of the study arms a binary restenosis rate of 0 percent. These findings provide clear indications of optimal dosing and a superior kinetic release profile for paclitaxel in reducing restenosis using the company's novel vascular drug delivery stent platform in the treatment of native coronary artery lesions.

PISCES is the most comprehensive pilot study conducted to-date of drug dosing and kinetics with drug eluting stents. Professor Patrick Serruys of Erasmus University in Rotterdam is the Principal Investigator of the trial, which is a multi-center study involving 191 patients from ten sites across seven countries, comparing the safety and performance of paclitaxel delivered at different rates and doses using Conor Medsystem's stainless steel MedStent™. Each patient participating in the PISCES trial received one of six different formulations of paclitaxel that varied by dose, drug release rate (fast, medium and slow) and directionality (drug release to only the arterial wall vs. release to both the wall and the lumen). There were at least 30 patients in each dosing group, with an average patient age of 59.

At four-month follow-up, all six formulations were determined to be safe, with a subacute thrombosis rate of 0.5 percent and 0 percent death from discharge to follow-up. Two groups with slow release (30-day) formulations had particularly good outcomes. In the 39 patient group receiving a 10mcg (per 17mm stent) slow release formulation delivered to the vessel wall, the in-stent binary restenosis rate was 0 percent and the in-stent angiographic late loss was 0.38 millimeters, with a 7.7 percent volume obstruction by Intravascular Ultrasound (IVUS). The target lesion revascularization (TLR) rate was 2.6 percent (intent to treat basis). In the 30 patient group receiving a 30mcg slow release formulation delivered to the vessel wall, the in-stent binary restenosis rate was 3.7 percent, with in-stent angiographic late loss of 0.30 millimeters, and 5.1 percent volume obstruction determined by IVUS. The TLR rate was 3.3 percent (intent to treat basis).

By comparison, the remaining four groups with faster release kinetics, ranging from 5 to 10 days for either 10mcg or 30mcg per stent, had less efficacy with respect to angiographic and IVUS endpoints. The results indicate that the drug release rate and direction of delivery have an effect on treatment outcomes, as well as confirm dosing regimens for the company's current clinical program.

"For the first time, we have a clear indication of the benefits of kinetic release and controlled dosing in improving patient outcomes," said Frank Litvack, M.D., Chairman and Chief Executive Officer at Conor. "We are pleased with these encouraging results which address significant problematic issues in this field and which support our unique stent and polymer platforms. The dosing information obtained from this study is contributing to the planning of our COSTAR and EUROSTAR studies, and the validation of the benefits of kinetic release has positive implications for the broad application of our platform for vascular drug delivery."

Unlike conventional drug eluting stents, Conor's are the first non-surface-coated stents specifically designed with polymer reservoirs for controlled, tailored release kinetics with the use of a fully bio-erodable polymer. Pre-clinical studies have demonstrated that there is no residual polymer or drug after the specified release period. Comparatively, MedStent required approximately one-tenth to one-quarter of the drug dose currently used with commercially available stents delivering paclitaxel.

Conor Medsystems is engaged in several international clinical trials for each of its drug delivery stent platforms – stainless steel and cobalt chromium. In addition to the PISCES trial for the company's stainless steel stent, Conor has two trials under way with its paclitaxel eluting cobalt chromium stent: COSTAR® (CObalt chromium STent with Antiproliferative for Restenosis) and EUROSTAR (EUROpean cobalt chromium STent with Antiproliferative for Restenosis). The company plans to seek regulatory approval for its proprietary cobalt chromium stent worldwide.

Release Kinetics
The Conor stent consists of hundreds of non-deforming reservoirs that house and protect the drug, providing up to six times the drug dose capacity compared to surface-coated stents. The reservoirs are the key to tailored release kinetics for controlled drug release (e.g., all at once or slowly metered out) and targeted delivery, including spatial and directional control (e.g., into the arterial wall or into the lumen). The reservoirs have the capability to release a broad spectrum of drugs and polymers – including lipophilic and hydrophilic compounds and biologics. In addition, the Conor stent can deliver multiple drugs with independent release rates and directionality.

In the Conor stent, the stresses and strains of the stent expansion are concentrated in and controlled by small, specially contoured features called "ductile hinges" which absorb all expansion forces. These hinges preserve the shape of the drug reservoirs preventing polymer deformation or extrusion during stent expansion.

Conor Medsystems, Inc.
Conor Medsystems, Inc., founded in 1999, is a pioneer in controlled vascular drug delivery. The company has developed novel stent and polymer technologies specifically designed for delivery of a broad spectrum of therapeutic agents. Conor's proprietary technologies allow release profiles to be tailored to the requirements of a drug and enable the delivery of multiple compounds to various sites in the body.

Conor Medsystems is positioned to become a technical, clinical, and market leader in the emerging field of vascular drug delivery with next generation drug delivery stents. The company's initial focus is on the treatment of restenosis and vascular disease, a market expected to exceed $4 billion by 2006. Conor is also exploring additional indications where controlled drug release from a medical device is expected to provide therapeutic advantage.