THURSDAY, March 29 (HealthDay News) -- For the first time, a
genetic test done at a patient's bedside helped doctors choose the
right medicine, Canadian researchers report.
The test, which can be done by nurses and others, was able to
identify patients in whom the blood thinner Plavix might be
ineffective, putting the patients at risk for heart attacks or
"One of the shortcomings we have in medicine right now is that there isn't a quick and effective way of identifying these genetic variants," said lead researcher Dr. Derek So, from the University of Ottawa Heart Institute.
"We have created the world's first point-of-care genetic test," he said. "We now have the means of selecting the right drug for the right patient."
The report was published in the March 29 online edition of
To prove the test works, So's team randomly assigned 200
patients to either receive screening for a gene called CYP2C19*2
using the gene test, or to regular care.
All of the patients had undergone a procedure called angioplasty
to open a blocked heart artery and had a stent placed there to keep
the vessel open.
Standard care after the procedure is to give patients Plavix to
prevent clotting. However, many patients have this gene mutation,
which makes the drug ineffective and patients more likely to
develop a clot that could result in a heart attack or stroke.
Among those with European ancestry, about 30 percent have this
mutation, and among Asians it's as high as 50 percent, the
Normally, after starting a patient on Plavix, a platelet
function blood test is done to see how the patient reacts to the
In this study, those getting the gene test were given a low dose
of Plavix and the others received a regular dose. Both groups were
given the drug so the researchers could judge the accuracy of the
rapid gene test using the platelet function test as
The researchers found the gene test accurately identified all
the patients with the gene mutation. Patients who had the mutation
were switched to a newer drug called Effient, which is not affected
by this mutation.
After one week, 30 percent of those in the standard group were
identified by the platelet function test as having a raised risk
for clotting, while none of those in the gene test group showed an
increased risk for clotting, So said.
"This is the first step required for personalized medicine," So said. "Ours is a proof-of-concept study. Now that we have this tool we can apply this same technology to different groups of patients and alter patient's therapy. We have taken bench to bedside."
One expert, Dr. Kirk Garratt, the clinical director of
interventional cardiovascular research at Lenox Hill Hospital in
New York City, thinks more proof is needed of the benefits of this
particular test, but its real value is its potential.
"Before anybody can get too worked up about the application of this technology in the clinic, we will have to see evidence that acting on the information provided actually yields benefit," Garratt said.
"There is one really dazzling benefit," he added. "These researchers have now shown that you can take a minimally trained allied health person and do accurate genotyping on patients in the clinic -- that is really big news."
The test is given by taking a swab from the patient's cheek,
putting it in a machine and getting a result in about an hour. The
test can be done by people who have never done genetic testing
after just 30 minutes of training, So said.
Larger trials will be needed to see if the test makes a
difference in patient outcomes, So noted. Spartan Biosciences,
which makes the test used in the study, funded the trial.
In terms of cost, the machine goes for about $10,000 and each
test kit is about $300, So said. That's relatively inexpensive if
it prevents patients from getting the wrong drug.
One advantage is that the test can be given before patients
receive their first dose of Plavix, So pointed out.
In addition, as Plavix (clopidogrel) becomes a generic drug --
as it is in Canada -- its cost goes down, while the newer drugs
like Effient (prasugrel) and Brilinta (ticagrelor) are very
expensive and are associated with an increased risk of bleeding, he
Commenting on the study, Dr. Amber Beitelshees, an assistant
professor of medicine at the University of Maryland School of
Medicine in Baltimore and author of an accompanying journal
editorial, said that "for the first time, a point-of-care genetic
test has been developed which can be used to rapidly screen
individuals who carry a particular gene and may benefit from an
anti-platelet drug other than Plavix."
Beitelshees added that "this is important because rapid
genotyping is necessary in order for genotype-guided therapy to be
incorporated into clinical care of patients undergoing coronary
interventions outside of clinical trials."
However, another expert thinks much more needs to be shown about
the value of this test before it can start to be widely used.
Dr. Gregg Fonarow, director of the Ahmanson-UCLA Cardiomyopathy
Center and co-director of the UCLA Preventative Cardiology Program
in Los Angeles, said that "there has been great interest in using
genetic testing information to guide selection of medications and
dosing, yet to date there has been little evidence that this
testing can improve clinical outcomes."
However, Fonarow continued, "as neither genetic testing for
variant CYP2C19 or platelet-function testing has been demonstrated
to improve clinical outcomes and routine use of these tests are not
currently recommended, further studies demonstrating any clinical
utility, if any, are needed."
For more on angioplasty, visit the
U.S. National Heart, Lung, and Blood
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