Boston Scientific is awaiting approval by the Food and Drug Administration of its new drug-eluting stent, called TAXUS, now that results from a new study on patients with coronary artery disease have shown that it significantly reduces the need for repeat angioplasty or coronary artery bypass surgery within a year.
"Restenosis remains the Achilles heel of percutaneous (performed through the skin) coronary angioplasty," said Dr. Greg Stone, Director of the Cardiovascular Research Institute and the Lenox Hill Heart and Vascular Institute. He presented the findings of the TAXUS trial at the 2003 Transcatheter Cardiovascular Therapeutics meeting in September.
Doctors place metal stents in the coronary arteries to provide a scaffolding to keep the vessel open after it has been cleared of artery clogging plaque. In about 25 percent of patients, smooth muscle cells grow and clog up the stent within six months, almost like a scar forming over an injury, necessitating a repeat procedure. This is called restenosis.
To solve the problem of restenosis, companies like Boston Scientific have begun covering their stents with drugs that interrupt the biological processes that cause restenosis. The first company to receive FDA approval for their drug-eluting stent was Johnson and Johnson’s Cordis. It received approval to sell CYPHER in the United States last April.
The TAXUS stent elutes a drug called paclitaxel into the artery over several weeks. Its efficacy was tested in a trial of more than 1,300 patients with coronary artery disease, whose average age was 62 years. The TAXUS drug-eluting stent was placed in half of the patients in the trial, while the other half received an identical looking stent that did not have a drug coating. Neither the patients nor their doctors were aware of which stent was being placed.
Patients were assessed at one, four, and nine months, and they will continue to be followed for five years. TAXUS reduced the need for repeat angioplasty or bypass surgery due to restenosis by 73 percent versus the traditional stent at nine months. It also reduced the need for additional catheterizations in the same vessel by 61 percent.
In another way of looking at the data, Dr. Stone said that 96 percent of patients with the TAXUS stent did not have a restenosis at nine months, compared to 87.5 percent of patients in the standard stent group.
The TAXUS stent was particularly effective in diabetic patients, and the company hopes the study results will give it an advantage over Johnson and Johnson’s CYPHER. Diabetics are considered high risk for coronary artery disease. When the researchers looked specifically at these patients, TAXUS was shown to prevent restenosis in 70 percent of the study participants.
In wrapping up the presentation, Dr. Stone concluded that TAXUS, "is effective in a wide range of complex patients and lesions, including small vessels, long lesions, and patients with diabetes."
Boston Scientific is anticipating approval of its new stent later this year or early 2004. TAXUS has been sold in Europe and other international markets since February.
