New Bedside Genetic Screen Yields Results In An Hour
A new point-of-care system accurately screens a patient's DNA for a single gene in an hour. The shoebox-sized device from Canadian-based Spartan Bioscience analyzes cheek swabs taken from heart attack patients for a common genetic variant, responsible for a potentially deadly reaction to the antiplatelet drug Plavix® (clopidogrel). As recently reported in The Lancet (unfortunately, the article is behind a paywall, but you can read the abstract here), the bedside system dubbed the Spartan RX enabled doctors to identify every patient in the study who was a carrier of the gene, allowing doctors to provide alternative medications for treatment. The device is the fruit of a joint venture with the University of Ottawa Heart Institute, which is Canada's largest cardiovascular center.
With plans to reduce analysis time by 50% and broaden the methodology to other genes, the Spartan device is a breakthrough for on-the-spot genetic testing and personalized medicine.
The story of the Spartan RX is a case in which the medicine is the sickness, not in a direct way, but in the sense that an administered drug in some patients does nothing because their body chemistry is different. When someone has a heart attack, it's a common procedure for a doctor to administer Plavix to prevent blood clots from forming, which could cause another heart attack or a stroke. This is done either within a few hours of the heart attack or after an angioplasty is performed to open up the arteries around the heart and a stent is installed to keep them expanded. Stents themselves promote blood clotting in certain patients, which is why some are designed to release antiplatelet agents themselves. In the U.S. alone, over a million stents are placed into patients every year, so this is an incredibly common procedure. Additionally, some patients take Plavix for up to a year, which is part of the reason why it is the second best-selling drug in the world (in 2011, it had $7 billion in revenue and it's about to become a generic drug, increasing its affordability).
However, patients with the genetic variant of the CYP2C19 gene, present in about 30% of Caucasians, 50% of Asians, and 55% of East Indians, have enzymes that are unable to activate Plavix, so the drug doesn't stop clotting. In fact, the study showed that patients who received a stent and were carriers of the variant were at a higher risk of death, stroke, or heart attack by as much as 42%. So the problem is that if patients can't activate the drug, it's as if they aren't taking anything. That means clotting can start right away, triggering another cardiac event (up to 50% occur within the first 48 hours). So the stakes couldn't be higher as the FDA issued a warning about Plavix in 2010 in regard to this problem.
So it's imperative that carriers of the genetic variant be identified and fast. Previously, the only option was to send a sample of the patient's blood out for analysis, which could take up to a week to get a result. But in the meantime, doctors were forced to gamble with Plavix.
But this latest report suggests that the Spartan RX changes all that and in an incredibly simple way. A nurse takes a cheek swab from a patient, even as the stent procedure is underway, and places the sample in the device. The sample is optically analyzed and an hour later, a printout provides the analysis of the genetic marker, even before the patient is ready for the first dose. By having such a straightforward methodology, it requires little additional training (30 minutes, according to the 200-patient study). And it's as sensitive and specific as standard DNA sequencing.
On top of being incredibly good news for anyone currently suffering or soon-to-be suffering with cardiovascular disease (and let's face it, that's a hell of a lot of us), the Spartan RX is the first step in rapid genetic analysis for the purpose of personalized medicine. Other genetic markers should be able to be screened with this methodology, allowing for even more bedside analysis for individualized care. As genetic research has implicated specific genes responsible for conditions, the bottleneck in genetic medicine has been shifting to the utility of this information in the clinical setting. Because the Spartan RX study was such a proof-of-concept investigation, it sets the standard for selecting genetic markers that can direct therapeutic decision-making in such a clear way.
The device is currently approved in Europe and is working on FDA approval in the U.S.; however, larger clinical trials will likely need to be conducted in order to demonstrate the utility of the device across a much larger section of the demographic and in a variety of clinical environments. Still, these initial results are very promising.
Hopefully, the day will come when every patient's genetic profile is immediately accessible so that all critical genes can be identified to determine the best treatment choices. Obviously, medicine isn't there yet, even as genetic testing becomes more convenient. But Spartan Bioscience has taken an important step forward in producing a device that, within an hour, allows doctors to fulfill that part in the Hippocratic Oath which says, "I will give no deadly medicine to any one if asked."
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