Stents Go Under the Microscope

A series of articles compares data on the Cypher and Taxus stents.
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Two drug-coated arterial stents have similar safety profiles, but the edge in some other measurements goes to the Cypher from

Johnson & Johnson

(JNJ) - Get Report

over Taxus by

Boston Scientific

(BSX) - Get Report

.

That's the theme of articles published today in the

Journal of the American Medical Association

and the

New England Journal of Medicine

. But it's unclear how these articles might affect sales of the products -- Taxus is the U.S. market leader -- because the authors say additional research is needed in order to make a better comparison.

"Our finding needs to be confirmed by longer follow-up studies," say the authors of an article in the

Journal of the American Medical Association

, which analyzed the results of six previous clinical trials involving the stents.

"A large-scale randomized trial may help settle this score more definitely," says an editorial in the

New England Journal of Medicine

, which also assessed previous clinical trials.

In examining the wire-mesh tubes that are inserted into arteries to improve blood flow, the

JAMA

article and the

NEJM

editorial say Cypher patients have a statistically significant lower rate of arterial reclogging and a lower rate of repeat treatments with stents.

Drug-coated stents are inserted into arteries to help reduce the risk of heart attack or stroke. They're inserted into patients who have undergone angioplasty, a process that unclogs an artery filled with plaque.

These drug-coated stents release a chemical to reduce this risk of reclogging, or restenosis. Drug-coated stents have virtually supplanted uncoated stents, which are also known as bare metal stents. Uncoated stents do a better job than angioplasty alone in reducing the risk of reclogging.

The

JAMA

and

NEJM

authors say they're not sure why the Cypher stent performed better than the Taxus stent in these medical indicators. The difference could be due to stent design, the mechanisms that enable the drugs to be released from the stents, or the drugs themselves. Cypher uses a drug called sirolimus, while Taxus uses the drug paclitaxel.

"Other unidentified factors may as well be responsible for the observed difference in performance between the two stents,"

JAMA

says.

None of the articles offers new research. The

JAMA

article and the

NEJM

editorial focused on a statistical compilation of previous clinical trials. Two other

NEJM

articles described clinical trial results that had been presented at medical conferences.

In

JAMA

, the authors concluded that Cypher had a lower rate of restenosis and a lower rate of target lesion revascularization, or the need to put in another stent at previously treated site.

The rates of death, heart attack and stent-related blood clots were statistically similar for both stents.

Researchers looked at six clinical trials involving 3,669 patients, conducting a statistical examination, known as meta-analysis, to integrate the data from several studies. The eight

JAMA

authors are affiliated with medical institutions in Germany, Spain and Switzerland. Although two have received research grants or lecture fees from some U.S. companies, they haven't received any payments from J&J or Boston Scientific.

The

NEJM

editorial adds that overall data suggest that Cypher provides a "clinical edge" but that Taxus "holds an edge on availablility, deliverability and cost."

In calling for a more definitive comparison, the editorial writer, Dr. David J. Moliterno noted that some of the tests that he reviewed "have limitations that affect the reliability of their findings." In two of the tests, for example, he said the number of patients tested was "moderate," and each clinical trial was conducted at only two study centers.

Moliterno added that the testing of second-generation stents and stent delivery systems "is already well under way." Moliterno is chief of cardiology and co-director of the Gill Heart Institute at the University of Kentucky. He has received payments from Boston Scientific and

Guidant

(GDT)

for serving on independent data-safety monitoring committees which evaluate clinical trials of stents.

Guidant is one of several U.S. companies trying to develop drug-coated stents. Other competitors include

Medtronic

(MDT) - Get Report

, which late last month received European Union approval for its Endeavor drug-coated stent, and

Abbott Laboratories

(ABT) - Get Report

. The various articles published today only looked at the J&J and Boston Scientific products.