Friday, March 09, 2007

New Bedside- Diagnostics Tool

Continued from page 1

By Peter Fairley

Doyle says it would not be "unrealistic" to imagine commercializing the detection system within five years. The biggest challenge ahead, he says, is developing a more practical detection system. To date, he and his colleagues have used a jerry-rigged ultraviolet microscope--a bulky, impractical system that costs tens of thousands of dollars--to detect and identify particle probes bound to their targets. "I don't imagine that for bedside use, people are going to want a microscope in every single room," says Pregibon. "We need detectors that are portable and robust and can withstand repeated use."

Doyle and Pregibon predict that if they succeed, their system could play a role in the detection of disease but also in identifying DNA or protein signals indicating which therapies will be most successful for a given patient. In 2005 the Food and Drug Administration approved a microarray that does just that: the AmpliChip test produced by Swiss-based pharmaceutical maker Roche. The test probes for two genes that influence how drugs such as certain antidepressants break down, and it can therefore predict whether someone is at risk of an adverse reaction to the drug, or may not respond to the drug. That system's high price has limited its use.

Still, Groves warns that there's plenty of work ahead. "It is still the Wild West when it comes to microfluidics and automation," he says. "There are a lot of drastically different concepts out there, some of which are being developed into products, and many of which fail. It's hard to know what will prove to be an industry standard 10 years from now."

Groves points out that in order to be practical, the detection device will need to be able to crunch through large volumes of particles without clogging or otherwise failing. "I wonder about the fidelity of the system if it must run tens of thousands of assays continuously," he says.

Adam Singer, an emergency-medicine specialist at Stony Brook University whose research has confirmed the value of bedside diagnostics in speeding up treatment, offers another word of warning. Singer says that cheap multitarget tests like Pregibon's will be of little use if more science isn't done to nail down markers that are truly instructive. Most microarray tests developed to date, Singer says, provide "general direction" in diagnosing illness, but not much more. "We're still quite a ways away from being able to apply these technologies clinically. Sometimes the technologies are more advanced than the knowledge and the evidence."