Nov 15, 2000
Intravascular Beta Radiation Therapy Shown to Reduce Recurrence of Coronary Artery Blockages

Data from INHIBIT Trial Shows In-Stent Restenosis Reduction With Radiotherapy

Indianapolis, Ind. and Santa Clara, Calif. - Results from the INHIBIT (INtimal Hyperplasia Inhibition with Beta In-stent Trial) trial show that use of Guidant Corporation's (NYSE and PCX: GDT) Intravascular Radiotherapy System can reduce the recurrence of coronary artery blockages in patients who have received a successful interventional cardiology procedure. Clinical data show that treating a previously stented artery with a small dose of beta radiation significantly reduced the rate of re-occurring blockages in coronary arteries. Ron Waksman, M.D., who served as the principal investigator for the INHIBIT clinical trial, presented the data today at the 73rd Scientific Sessions of the American Heart Association in New Orleans. Waksman is director of experimental angioplasty and vascular brachytherapy, Washington Hospital Center, Washington, D.C.

Key findings from the INHIBIT trial show:

• Recurrent restenosis rates for patients treated with radiotherapy were 50 percent lower than patients in the control group, with a recurrent restenosis rate of 26 percent for radiotherapy patients as compared to 52 percent for patients in the control group.

• The incidence of the primary endpoint of major adverse cardiac event (MACE, a composite of death, Q-wave myocardial infarction and repeat vascularization of the target site) among radiotherapy patients at nine months was 56 percent lower than patients in the control group. Data from radiotherapy patients show a MACE rate of 14 percent, as compared to 31 percent for the control group.

The trial was designed to evaluate Guidant Corporation's Intravascular Radiotherapy System for the treatment of in-stent restenosis in native coronary arteries with diameters from 2.4 mm to 3.7 mm and a maximum treated length less than 47 mm. The prospective, double blinded, multi-center randomized trial enrolled 332 patients suffering from coronary artery disease at 27 centers worldwide.

"Results of the INHIBIT trial show that intravascular radiotherapy can significantly reduce recurrent restenosis, offering patients a new, promising treatment for coronary artery disease," said Waksman. "It is clear from the INHIBIT trial that Guidant's Intravascular Radiotherapy System significantly reduces recurrent restenosis by stopping excessive cell proliferation within the artery."

Restenosis - re-occurring blockages of coronary arteries - is caused by excessive cell growth in previously treated coronary arteries as a response to an interventional procedure such as angioplasty and stenting. It is one of the biggest challenges in cardiovascular medicine today. More than 1.5 million people worldwide undergo coronary angioplasty and related procedures each year. However, 30 percent to 50 percent of angioplasty patients experience re-blockages within six months of their initial procedure.

Coronary stents, which are tiny metal tubes that function as scaffolding to hold previously blocked arteries open, have been greatly successful in reducing restenosis. This condition, however, still develops in approximately 20 percent of patients implanted with stents. Intravascular radiotherapy has shown to be effective in allowing a significant number of patients to avoid repeated interventions and, in some cases, coronary bypass surgery.

Patients enrolled in INHIBIT underwent treatment utilizing Guidant's Intravascular Radiation System. The system, which is fully automated and utilizes beta radiation, is a three-component system consisting of a centering catheter, source wire and source delivery unit. Following angioplasty and/or stenting, the physician advances the centering catheter through the artery until it reaches the treatment area. The source delivery unit automatically advances the source wire, containing the radioisotope Phosphorus 32 (32P), through the centering catheter to the diseased coronary artery. An automatically calculated, precise dose of beta radiation is then delivered to that exact area for a predetermined period of time ranging from three to five minutes. The source wire is then automatically retracted back into the source delivery unit to complete the procedure.

"Data from the INHIBIT trial show that Guidant's Intravascular Radiotherapy System significantly reduces the incidence of re-occurring blockages in previously stented arteries," said John M. Capek,Ph.D., president of Guidant's Vascular Intervention Group. "As awareness of this new treatment and the radiotherapy field in general grows, we're confident that Guidant's beta radiation system will be the treatment of choice among physicians."

In May 2000, Guidant announced that its GALILEO(tm) Intravascular Radiotherapy System received CE Mark approval, making the system available in Europe and in other countries that base regulatory approval for medical devices on the European CE Mark. The approval was based on results of the PREVENT (Proliferation REduction with Vascular ENergy Trial) clinical trial, which showed that patients who received radiotherapy had a restenosis rate of 8 percent at the lesion site, compared to a 39 percent restenosis rate for control patients who did not receive radiotherapy. The GALILEO System is currently limited to investigational use in the U.S.

In conjunction with the international launch of the GALILEO System, Guidant is currently enrolling patients in the VISION (Vascular Intervention Study with IONizing Radiation) trial. This is a non-randomized evaluation of the GALILEO System in the treatment of patients with de novo (first time), restenotic (re-occurring) and in-stent restenotic native coronary artery lesions.

A global leader in the medical technology industry, Guidant Corporation provides innovative, minimally invasive and cost-effective products and services for the treatment of cardiovascular and vascular disease.