Gamma Radiation Treatment of Coronary Ateries

[Michael J Vala <michael.vala@bms.com>]

RadSafers -

Below is a press release from Cordis detailing the outcome of a
study evaluating the effectiveness of radiation treatment to
prevent the restenosis of coronary arteries.  They are using
Ir192 to internally administer 13.5 Gray doses to the affected
areas.  Can't they use something less energetic than Ir192 to
irradiate such a localized area?  They don't specify source
strength or exposure times but if the arteries are receiving 13.5
Gray, what about the patient's thyroid and sternum or the
attending medical staff?

Regards,

Mike Vala
Bristol-Myers Squibb
michael.vala@bms.com
*******************************************************

Thursday September 23, 2:15 pm Eastern Time

Company Press Release

SOURCE: Cordis Corporation

GAMMA 1: Major Clinical Trial Cites Efficacy and
Safety of Gamma Radiation At Nine Months for Treating Reclogged
Stents
in Coronary Arteries

WASHINGTON, Sept. 23 /PRNewswire/ -- Nine-month follow-up results
of a newly completed landmark randomized
clinical trial using a catheter-based, gamma radiation (Ir-192
[Iridium]) ribbon for reduction of in-stent restenosis [patients
with
reoccluded or reclogged stents] indicates this treatment
significantly reduces repeat blockage and may reduce the need for

follow-up treatment of the affected artery.

The study utilized gamma-ribbon radiation therapy licensed from
Best Medical, Inc. by Cordis Corporation, which funded the
clinical trial. Cordis is a Johnson & Johnson company.

Known as the GAMMA 1 Study, highlights of the clinical trial were
presented today during annual scientific sessions of the
Transcatheter Cardiovascular Therapeutics symposium, an
interventional cardiology meeting in Washington, D.C. Cordis
submitted the results on schedule in a full PMA review submission
to the FDA in June of this year.

Martin B. Leon, M.D., Chairman, Cardiology Research Foundation,
Washington Hospital Center, Washington, D.C., and
Principal Investigator, said the study is the first major
randomized, multicenter, placebo-controlled clinical trial to
evaluate the
efficacy of gamma radiation treatment for in-stent restenosis.
Conducted at 12 sites in the United States, the study included
252
patients with native coronary artery disease and in-stent
restenosis.

The results reported at the Transcatheter Cardiovascular
Therapeutics (TCT) meeting represent six-month angiographic and
nine-month clinical follow-up of these patients. The Cordis gamma
radiation treatment system employed in the study is a
closed-end lumen catheter that accommodates a 0.030-in. diameter
ribbon with 6, 10, or 14 seeds of Ir-192.

All patients in the study were diagnosed with severe in-stent
restenosis. Average lesion length in the GAMMA 1 trial was
20.0-mm and patients were randomized to receive radiation or
placebo after treatment of their in-stent restenosis with PTCA
[angioplasty], certain atheroablative techniques or an additional
stent. The mean dose of radiation administered was 13.5 Gy
[Gray] at a distance of 2-mm from the ribbon source.

``The key findings of this landmark study were a 41% reduction of
in-lesion restenosis (p = .001) and a 57% reduction of
in-stent restenosis (p < .001),'' Dr. Leon said.

``Analysis of an intravascular ultrasound subgroup revealed
decreased intimal hyperplasia [tissue proliferation] and
increased
lumen area [vessel diameter] in radiation-treated patients at
follow-up,'' he continued. ``It is worth noting these impressive
results were obtained despite the fact that 50% of the patients
had suboptimal placement of the radiation device ['geographical
misses'],'' Dr. Leon said.

``The results were even more impressive in patients with shorter
lesions, treated with 6- and 10-seed ribbons, and in diabetic
patients,'' said Dr. Leon. ``In addition,'' he said, ``there were
very few procedural problems. Coronary radiation therapy was
associated with similar (and infrequent) in-hospital adverse
events (3.2% placebo vs. 2.3% radiation therapy).''

``A clear dose response relationship was observed for the
radiation patients, which supports the use of higher (> 14 Gy at
2mm) radiation doses to achieve optimal angiographic results,''
he said.

Paul Teirstein, M.D., Director, Interventional Cardiology, of the
Scripps Clinic, La Jolla, Calif. and one of the key investigators

in the trial, made the following additional observations about
the details of the study: ``Late stent closure (30-270 days
post-procedure) was more frequent in the radiation-treated
patients compared to the placebo group. However, it is important
to note all of these events occurred in patients who had a new
stent placed at the time of the radiation, and none of these
events
occurred in patients who were still receiving ticlopidine or
clopidogrel [antiplatelet therapies].

``Therefore, I think we need to be very careful to avoid placing
new stents at the time of radiation, if at all possible, and to
continue antiplatelet therapy for at least six months,'' Dr.
Teirstein continued. ``In my view, this will resolve the problem
and
maximize the risk-benefit value of this very important therapy.
It is worth noting the reduction in restenosis with radiation was

even greater in the patients who did not have new stents
placed.''

Dr. Leon stated: ``These results are extraordinarily impressive
for the first multicenter study for in-stent restenosis. This
clinical
trial definitively shows gamma radiation with Iridium 192 is not
only feasible but is the treatment of choice for physicians
wanting
to give their patients with severe in-stent restenosis the best
treatment, keep precise control over the procedure and get it
right
first time. Gamma radiation can be used safely and effectively in
patients with one of the most intractable cardiovascular
problems that we face today.

``Furthermore,'' Dr. Leon noted, ``this provides critical
confirmation of the important pioneering work previously reported
in
single-center trials by Dr. Teirstein in the SCRIPPS Trial, and
Dr. Ron Waksman, of Washington Hospital Center, in the
WRIST Trial. It also shows these results may be generalized to a
wide range of other institutions.''

Since its establishment in 1959, Cordis Corporation, along with
its subsidiaries, has been a pioneer in circulatory disease
management, and is the world's largest, most comprehensive
developer and manufacturer of innovative products for
interventional medicine, minimally invasive computer-based
imaging, and electrophysiology. In 1996, it merged with Johnson &

Johnson to form Cordis, a Johnson & Johnson company, with
approximately 3,500 employees worldwide.

SOURCE: Cordis Corporation

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