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Noninvasive diagnostic technologies emerging
In science fiction, patients don't complain about the inconveniences associated with diagnostic testing. "With the Star Trek approach to medicine, you don't even need physical contact to diagnose illnesses," says Sayed Badrawi, vice president of marketing at Pacific Biometrics Inc. (Lake Forest, CA). "You can determine a patient's condition simply by scanning the body."
Hemoscan 1000 from Cytometrics measures hemoglobin and hematocrit levels without drawing blood.
In the real world, however, patients do complain about the constant poking and prodding that their physicians must subject them to in order to diagnose or monitor their conditions. So it's little wonder that diagnostic manufacturers are working to devise products that are more patient-friendly. While manufacturers haven't yet achieved Star Trek status, progress in the development of noninvasive diagnostic technologies is being made along several fronts, and for a variety of conditions. Some companies are employing existing technologies but substituting body fluids that can be obtained noninvasively—such as urine, saliva, or sweat—for blood. Other companies are developing new technologies. Still others are finding alternative applications for current testing methods.
Calypte Biomedical Corp. (Berkeley, CA) is developing an HIV-1 testing system that uses urine instead of blood. A urine-based HIV-1 test system is both less expensive and more effective than blood testing, according to the company. The first of the company's two-part test screens for the antibodies produced after exposure to HIV, the second confirms the presence of the antibodies. According to Bill Boeger, Calypte president and CEO, a noninvasive, inexpensive, and accurate test for HIV—such as the urine test—is needed to facilitate HIV-1 detection. "In the past, many people who may be at risk for HIV infection have declined testing because of the pain, cost, and inconvenience of having their blood drawn," says Boeger. He expects that by making urine HIV-1 testing widely available, many people who have previously declined blood testing will now come forward.
Salivasac saliva-collection and -processing device.
According to the company, the system's efficacy is similar to that of blood testing. Clinical trials were conducted on individuals who had previously been found to be HIV-1 antibody positive through blood testing. When their serum and urine samples were tested, the results showed that the sensitivity of the urine Western blot was 99.7%. In cases where blood testing was indeterminate, the urine test provided a definitive result of negative in 105 of 109 seroindeterminate samples. "The urine Western blot provides a remarkably low frequency of indeterminate results, which is a clear advantage over blood testing in a laboratory environment," says Toby Gottfried, Calypte director of research and development.
Like Calypte's urine test, the Salivasac saliva-collection and -processing device from Pacific Biometrics uses a noninvasively obtained body fluid to replace blood. The device automatically filters a saliva sample so that it can be used in a point-of-care assay. The company is developing a series of saliva-based point-of-care glucose measurement products for screening and eventual monitoring of diabetes. The company is also pursuing assays for cyclosporin monitoring, detection of drugs of abuse, and measurement of hormones and metabolic markers.
The Osteopatch sweat-collection device and proprietary quantitative assays for detecting biochemical markers of bone loss.
Representatives from both Calypte and Pacific Biometrics will be speaking about their noninvasive technologies at the American Association for Clinical Chemistry's Oak Ridge Conference, "On the Road to Noninvasive Testing," which will be held April 23–24 in San Jose. Cosponsored by IVD Technology, the conference will include sessions on the use of alternative body fluids in testing—technologies such as those of Calypte and Pacific Biometrics—and will also feature speakers from companies that are creating totally new technologies, as well as those that are making use of existing technologies for new, noninvasive diagnostic applications.
Cytometrics Inc. (Philadelphia) is one of the companies developing a new testing technology. Created in conjunction with the American Red Cross, the company's product is designed to screen for anemia in the blood. "Hemoscan 1000 measures hemoglobin and hematocrit levels using a noninvasive photonic-based imaging technique," says Tammy Duffy, Cytometrics market analyst. "The probe is placed under the tongue, eliminating the need for a needle stick."
The small, portable unit captures computer images of the blood flowing through the capillaries in the underlying mucous membranes of the mouth. The device reads these images and computes the donor's hemoglobin and hematocrit levels without drawing blood. According to Duffy, Cytometrics is planning to file a premarket notification with FDA by the middle of this year. The company intends to target the acute-care and blood-bank markets.
Some diagnostic companies are using existing technologies for new applications. Although the utility of sweat as a diagnostic fluid has been known for many years, Pacific Biometrics has applied a new collection technology to develop a test that measures bone loss and the rate of a patient's bone deterioration. According to Badrawi, the Osteopatch system includes both an optimized sweatpatch collection device and a proprietary quantitive assay for detecting biochemical markers of bone loss in sweat.
The patch is worn continuously for 2 to 5 days to accumulate the nonvolatile components of sweat and is then peeled off and mailed to the lab for processing. "Because the patch is constantly collecting sweat, it is equivalent to collecting multiple samples of urine or blood, providing a time-integrated representation of the patient's bone-marker concentrations," says Badrawi. "This is an important advantage when trying to measure analytes that exhibit significant diurnal or day-to-day variability."
The Osteopatch meets the need for a cost-effective diagnostic tool that will help identify those at risk for rapid bone loss and possible osteoporosis, according to Badrawi. It will also help physicians to select treatment options and monitor their effectiveness. The Osteopatch is currently undergoing clinical trials and is expected to be commercially available in the United States in approximately two years. The sweat-collection patch has recently received the CE mark and is commercially available in Europe. The immunoassay kits used in conjunction with the patch are also available in Europe.
With the new crop of technologies now in development, diagnostic companies predict that fulfilling the promise of science fiction is only a matter of time. "In terms of new-product revenues, this is a slow-growing field," says Badrawi, "but moving to noninvasive diagnostics is definitely the next big leap for diagnostic companies."—Susan Wallace
