FDA Advisory Panel Recommends Approval
for Abbott's XIENCE™ V
Drug Eluting Heart Stent
9-1 Vote May Mean 4 Drug-Eluting Stents Will
Be Available in the U.S. Next Year
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November 29, 2007 -- Gaithersburg, Maryland --
The FDA Circulatory System Devices Advisory Panel, which met today
to hear data and opinions from the manufacturer, as well as outside
experts, on the safety and efficacy of Abbott's XIENCE V Drug-Eluting
Stent, has voted 9-to-1 to recommend approval. The FDA is not required
to follow the Panel's recommendation, but usually does.
The single dissenting vote came from Dr. John C.
Somberg, a professor of Clinical Pharmacology at Rush University
Medical Center, who had previously expressed concern that Abbott's
clinical trials had
not
yet provided sufficient safety assurance for the period beyond 12
months. The issue of late stent thrombosis, or
blood clots forming more than 12 months after stent implantation,
surfaced last year around the previously-approved drug-eluting
stents: the CYPHER, made by Cordis / Johnson & Johnson, and
the TAXUS, from Boston Scientific. The safety issue became paramount
and was the subject of a much-reported on two-day meeting of this
same FDA Panel on December 7-8, 2006, so the Panel members were already
quite sensitive to these concerns.
Post-Market Follow-up Required -- No Delay
Seen
The Panel recommended
approval, based to a great extent on Abbott's promise to do a long-term
post-market
follow-up to track the safety. Some financial analysts expressed
concern that the time needed for Abbott to design this longer term
follow-up
study might delay approval of the XIENCE. However, Abbott currently
has several larger XIENCE studies in process and recently announced
the hiring of Dr. Charles Simonton as Chief Medical Officer for the
cardiac group at Abbott Vascular. While at the Carolinas Heart Institute
in North Carolina, Dr. Simonton headed up the
STENT Registry, currently one of the largest data sets of stent patients
which has regularly issued long-term follow-up reports since its inception
4 years ago. His expertise and experience, along with clear indications
that the FDA was going to require all stent manufacturers to include
much
larger
and
longer
term post-market studies than the Agency had in the past, would indicate
that Abbott already is far along in designing such a study, and this
should not represent a significant delay.
"Stent Wars" Expand
For the past 3-4 years, the U.S. drug-eluting stent market has been
under the sole purview of the CYPHER and TAXUS stents, both of them
first generation devices. Last month Medtronic's Endeavor received
unanimous
FDA Panel
approval
-- along with today's vote, there may soon be four stents in the
U.S. market, with two of them being newer designs. According
to many cardiologists, these new DES are based on a more advanced
and better-performing stent platform. Prior to the introduction
of drug-eluting stents, Abbott's (formerly Guidant's) Multi-Link
and Medtronic's Driver bare metal stents, were thinner, stronger,
more
deliverable and showed a lower restenosis rate than other bare metal
stents. Additionally, both manufacturers claim to have developed
more biocompatible coatings.
The safety profile of Medtronic's new stent has
been borne out in large studies, with some data going out to five
years. Abbott's XIENCE V, while it doesn't have as large a data set,
has shown significantly improved results and in a recent study, demonstrated
a 43% reduction in MACE (Major Adverse Cardiac Events, such as heart
attacks, death, re-intervention) over its chief rival, Boston Scientific's
TAXUS.
The size of the drug-eluting stent market worldwide
has shrunk considerably over the past year, as safety concerns drove
a switch back to bare metal stents and as other studies even questioned
the need for some stent procedures. However, most observers of the
interventional cardiology scene
agree that,
if approved,
Medtronic
and Abbott will
be taking
major market share from Cordis and Boston Scientific -- although
Boston, as part of its acquisition agreement with Guidant, has the
right to sell Abbott's XIENCE under its own brand name PROMUS, so
it will in effect share in the fruits of its own flagship stent's
demise.
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