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Vascular Stenting - The procedure involves an
introduction of a stent which is collapsed to a small diameter,
into the blood vessel on a balloon catheter. The
catheter is then maneuvered into the blocked area of the artery. When
deployed, the balloon is inflated and the stent expands to the appropriate diameter.
The balloon is deflated and withdrawn, the stent locks in place and forms a scaffold to
open the vessel lumen and reinstate blood flow.
With
most patients, the bare-metal stents produce no long-term
complications and little or no side effects but in
approximately 15%-30% of patients, the artery becomes
clogged again (a condition called restenosis) within a
year, and it must be treated again. When a
bare-metal stent is implanted in an artery, the body
reacts naturally to heal itself by producing a layer of
new cells which will eventually cover the stent. While this covering of the stent is a natural
healing response, the layer can become too thick,
leading to a narrowing of the vessel and reduced blood
flow.
In
recent years, doctors have used new types of
stents called drug-eluting stents. These are
coated with antithrombotic, anti-inflammatory
or antiproliferative drugs that are slowly
released and help keep the blood vessel from
reclosing. Clinical
trials have shown that after one year, patients
with uncoated stents, restenosis occurs in 14.7%
of patients while the restenosis rate in patients
who receive a drug-eluting stent is about 4.2%.
These patients require fewer repeat procedures
(e.g., additional angioplasty, bypass surgery) and
have a lower risk for heart attack.
A
drug-eluting stent has all the structural features
of a bare-metal stent. The major difference
between the two is that a drug-eluting stent has a
coating of a polymer which releases a restenosis-fighting
drug. The special polymer coating on the stent
provides for consistent and even distribution of
the drug from the stent. The
average cost for a drug-eluting stent, about
$3,000 per unit, is three times higher than that
of a bare-metal stent.
Major Players -
Newton, MA-based Boston
Scientific Corp (NYSE: BSX),
which received the U.S. Food and Drug Administration
(FDA)
approval to sell a coated stent in March, said in
July it had taken a 70 percent share of the U.S.
market for drug-eluting
stents with
its
TAXUS™ Express²™ Paclitaxel-Eluting Coronary Stent
System.
TAXUS which is one of two approved drug-coated stents by
the FDA, uses a cytostatic drug known as paclitaxel,
developed by British
Columbia-based Angiotech Pharmaceuticals Inc. (NASDAQ:ANPI;
TSX:ANP).
Paclitaxel, which is extensively used in cancer therapy,
interferes with the ability of the vessel cells to
divide and multiply, therefore reducing restenosis and
reduces rejection of the stent by slowing cell
division around the stent. The
TAXUS stent uses Translute™ Polymer, a
proprietary polymer carrier technology, to control
drug release.
In May 2004, Mr. Jim Tobin, President and Chief Executive Officer of Boston
Scientific announced that the TAXUS launch continued to go
extremely well, with sales growing and execution remaining
strong. "More broadly, April was the first full month
of TAXUS sales, which helped drive us
to nearly $500 million in total sales for the month, an annualized run rate of
approximately $6 billion...", added Mr.
Tobin.
The three recalls of Boston Scientific Corp. cardiac stents since July 2 affected
as many as 165,000 stent systems and had a financial impact
in a sales reversal of $35 million and an inventory write-off of $43
million in the second quarter 2004. Based upon
our estimation,
Angiotech Pharmaceuticals,
who is in a co-exclusive license agreement
with Boston Scientific, could receive as much as $150
million in royalties this year, based upon the
TAXUS
current forecasted sales.
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