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GenTel BioSciences Developing Allergen Chip to Compete with Common Skin-Prick Allergy Test


GenTel BioSciences is developing a 22-allergen chip to test for respiratory allergies that it expects will compete with standard skin-scratch tests, the company said this week.

GenTel recently received a two-year, $1.2 million Phase II Small Business Innovation Research grant from the National Institutes of Health to develop the allergy test kit. According to Todd Strother, the principal investigator and R&D team leader for the project, the company expects to have a test available for clinical beta testing within a year, and a test out on the market in the US by the end of 2008.

"We want to be competitive with the skin test, and the skin test is in the neighborhood of $15 to $20 per allergen, or skin prick," said Strother. "We want to be cheaper and faster. Our ultimate goal is to place this system in primary care physicians' offices. We want this to be cheap, fast, and easy enough to use so that nurses and technicians in a regular doctor's office can take a pin prick sample, put it on our device, and within the length of time of a normal doctor's visit, have an answer."

According to a report by the Genesis Group, a market research company based in Montclair, NJ, about 17 million people in the US are tested every year for allergies. This means that the market GenTel will be entering is around $7.5 billion on the high end.

"We want to be competitive with the skin test, and the skin test is in the neighborhood of $15 to $20 per allergen, or skin prick. Our ultimate goal is to place this system in primary care physicians' offices. We want this to be cheap, fast, and easy enough" for nurses and technicians in doctors' offices.

GenTel's flagship product is its PATH nitrocellulose slide, which was originally licensed from Decision Biomarkers and launched in late 2004. The slide serves as a "blank chip" on which customers print their own proteins.

GenTel is now expanding on its PATH slide to develop chips with content. The company began developing its allergen chip in the beginning of 2005. During the first phase of development, funded by a six-month, $180,000 Phase I SBIR grant, Strother's research team immobilized five different allergens on slides, and used the slides to test serum samples from about 10 different patients.

The researchers then compared the results of their chip test with results from skin tests and ELISA tests that were done on the same patients.

"I don't have the exact statistics worked out, but pretty much nine out of 10 times, or 11 out of 12 times, a positive reaction on the skin test showed elevated antibody binding on the chip test," said Strother.

With traditional skin tests, patients are stuck with a shallow prick that has a particular allergen on it. If they develop a red spot and welt in the place where the prick was stuck, they are likely to be allergic to that allergen. A typical skin prick-based allergy test tests for 22 different allergens. GenTel is looking to mimic that test by spotting down 22 different allergens on a chip, Strother said.

The main advantage of the chip test over the skin test is that patients only have to be pricked once in the finger, rather than being stuck with a multitude of different pricks with different antigens on them.

"Puncture tests are uncomfortable, particularly for children and the elderly. And in some cases, puncture tests can elicit severe adverse allergic reactions," said Strother.

The chip test is also advantageous over ELISA tests in that it requires much less blood, and it is faster, said Strother. While an ELISA test requires a few milliliters of blood, the chip test requires only one to two microliters of blood. And while it may take a few days, or even weeks to get results from an ELISA test, results from the chip test can be delivered in about two hours, Strother said.

For the Phase I, five-allergen chip, which contained allergens from cat, mold, and two dust mites, the allergens were purified proteins. However, for its Phase II, 22-allergen chip, GenTel is considering using allergen extracts.

"When you buy an extract, they grind up the cat hair, or dust mite, or whatever, get rid of what's not dissolved, and there's a bunch of stuff in there that's not protein, and only a few proteins of interest in there that actually cause the allergic reactions," Strother explained.

The main advantage of using extracts over purified proteins is that extracts are cheaper, Strother said. In addition, extracts could conceivably decrease the number of false positive results, because an extract could contain multiple proteins that cause allergic reactions, while a purified protein is only one protein that causes an allergic response.

"With dust mites, there's not just one protein that causes allergic response," said Strother. "If we only printed one down, we might miss people who are allergic to another dust mite protein."

Immobilizing extracts presents some technological problems in that the multitude of proteins and soluble carbohydrates may interfere with binding of antibodies, resulting in a high background, Strother said.

"If it doesn't work, we can use purified proteins," he said. "There are just fewer of them that are available out there."

GenTel's major collaborator so far in testing out its allergen chip is Robert Bush, a professor of medicine at the University of Wisconsin-Madison School of Medicine and Public Health. Bush has supplied GenTel with serum samples and patient histories, including results from patients' skin tests and ELISA tests.

"There is great potential here for a much simpler allergy diagnostic tool that can improve patient care, comfort, and time of diagnosis," said Bush.

Aside from developing the allergen chip, GenTel is also developing a coagulation chip to help diagnose blood clotting disorders, such as hemophilia and thrombosis, and a cancer chip that targets prostate and pancreatic cancer. According to GenTel CEO Alex Vondenlich, the coagulation chip is expected to launch mid-summer.

— Tien-Shun Lee ([email protected])

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