XIENCE V™ Everolimus Eluting Coronary Stent System

September 23, 2009 -- San Francisco -- A new study shows that after one year the second generation XIENCE V drug-eluting stent from Abbott (NYSE: ABT) was more effective in keeping coronary arteries open than Boston Scientific's (NYSE: BSX) older TAXUS stent. In presenting the results of the SPIRIT IV clinical trial at this morning's session of the TCT 2009 in San Francisco, principal investigator Dr. Gregg W. Stone stated, "The SPIRIT IV results show that XIENCE V significantly reduces a patient's risk of experiencing a heart attack, the need for a repeat procedure or stent thrombosis."

The results were striking: Target Lesion Revascularization (TLR) -- a situation where the stented artery has to be re-opened because of reduced blood flow -- occurred almost twice as often in patients who received the TAXUS (4.6%) as opposed to the XIENCE V (2.5%). Both of these measures, however, are far lower than the restenosis rates historically seen with bare metal stents, which hovered in the 15-25% range. Another measure, a new FDA-requested end-point, called Target Lesion Failure (TLF) had similar results. TLF is a composite of cardiac death, heart attack attributed to the target vessel (target vessel myocardial infarction), and ischemia-driven TLR (ID-TLR) and it occurred in 4.2% of XIENCE V patients and 6.8% for TAXUS, a 38% reduction for the Abbott stent.

The breakdown for cardiac death or MI (heart attack) favored XIENCE (2.2% vs 3.2%) but did not reach statistical significance. Another measure of safety that has been of much concern with drug-eluting stents was that of stent thrombosis. Again the data favored XIENCE (0.29% vs 1.06%) but even a trial of this size is not powered to compare very low frequency events, such as stent thrombosis.

SPIRIT IV enrolled a cohort of 3,690 patients. Dr. Stone, Professor of Medicine at Columbia University Medical Center in New York, noted that this was a more powerful trial than earlier SPIRITs and was the largest head-to-head comparison of two drug-eluting stents to date. The trial also included a large number of diabetic patients -- Dr. Stone noted that there were more diabetic patients in SPIRIT IV than the total number of patients in the SPIRIT II trial. An important difference from other studies was that clinical decisions about whether the coronary artery stayed open were measured by whether or not the patient required a second procedure, not by angiographic follow-up, making the trial results more "real-world".

Gregg W> Stone MD

Jeffrey J. Popma MD

Commenting on the study, Dr. Jeffrey J. Popma of Beth Israel in Boston, praised the trial's design, saying that by taking all comers, complex patient groups and not using angiographic follow-up as the measure, this was the "right study". Popma stated, "In some of the earlier studies of CYPHER vs. TAXUS, I had questions, I don't have any questions now about XIENCE vs. TAXUS." One question that some cardiologists have raised is that, with several recent studies showing a "late catch-up" effect with drug-eluting stents from three to five years out, with the possible exception of Medtronic's Endeavor, will the differences between the XIENCE and TAXUS remain as great in four more years?

For example, another study presented this morning, the SIRTAX-LATE showed that the differences between the CYPHER and TAXUS stents seen in the first year became statistically not significant by year five, because of a greater late catch-up effect with the CYPHER sirolimus-eluting stent.

One area where the XIENCE and TAXUS were no different was in diabetic patients. TAXUS, which uses the drug paclitaxel, has shown good results with diabetics over many trials. However, one take-away from this trial is the increased safety and efficacy of the second generation of drug-eluting stents. Dr. Stone attributed this improvement to a number of factors: a better stent platform with thinner struts, a new and thinner drug-eluting polymer, and a different drug. When asked what the clinical implications of the SPIRIT IV study were for him, he replied, "Whenever we have a patient in the cath lab, we want to choose the safest, most effective stent. And today that's the XIENCE -- for non-diabetics. For diabetics, it's not as clear."

Reported by Burt Cohen, September 23, 2009

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