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'Peanut patch' aims to desensitize those with severe allergy

Dealing with peanut allergy could be a piece of cake if a new "peanut patch" lives up to its promise.

Applied to the skin like a Band-Aid, the sticky appliqué resembles the nicotine patch that reduces tobacco cravings. But instead of nicotine, it releases trace amounts of the troublesome protein found in peanuts.

The experimental treatment is based on desensitization, a method that exposes patients to minute doses of an allergen to help them develop tolerance without triggering immune reactions.

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The peanut patch is in clinical trials at research centres in France and the United States, including Duke University Medical Center in Durham, N.C., and National Jewish Health in Denver, Colo.

Results of the safety trials will be released this September, according to a statement from DBV Technologies, the Paris-based company that developed the Viaskin Peanut patch.

Desensitization is a proven treatment for respiratory allergies caused by pollen and dust mites. Patients receive tiny amounts of allergens via injections or drops placed under the tongue, and in most cases their symptoms become milder over time.

Conventional desensitization treatments are dangerous for patients with food allergies, however, since they are at increased risk of life-threatening anaphylactic reactions when the allergen enters the bloodstream.

To minimize the risk, the peanut patch presents the allergen to the skin's Langerhans cells (which regulate immune reactions) while preventing its passage through the skin, according to DBV Technologies. Unlike drops and injections, the peanut patch can be removed to halt treatment instantly.

In addition to the peanut patch, DBV is testing a patch to treat milk allergy. A pilot study conducted in France found that after three months of treatment, five out of nine patients with severe milk allergy were able to ingest small amounts of milk proteins without symptoms.

About 2.5 million Canadians suffer from a significant food allergy, according to a survey published in June, 2010, in the Journal of Allergy and Clinical Immunology. Almost 2 per cent of Canadians may be allergic to peanuts, the study found.

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Desensitization for people with peanut allergy remains a highly experimental therapy, says Donald Stark, a clinical allergist at the University of British Columbia.

He said in 1996, a U.S. study in which children were injected with peanut extract ended after a child had a fatal reaction, dying within seconds. "And that was in the clinic," Dr. Stark said.

Nevertheless, recent peanut desensitization studies have been promising.

In a study published in February, 2011, in the Journal of Allergy and Clinical Immunology, researchers at Duke University Medical Center and Massachusetts General Hospital administered increasing doses of peanut extract in drops under the tongues of nine children with peanut allergy. After 12 months of treatment, the patients could safely consume 20 times more peanut protein (about 1,700 micrograms) than a control group.

Peanut desensitization studies in Europe have produced similar results. But it's likely that researchers on both continents excluded patients with the most severe peanut allergies for safety reasons, Dr. Stark says.

"There are certainly suggestions that for people who have milder symptoms, some of these desensitization approaches might be of benefit."

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But Dr. Stark adds that the treatment may not be suitable for the extremely allergic patients who need it most. "I don't think the data is there to show that this is, in fact, a safe procedure for those types of patients yet."

Even so, people with milder peanut allergies can hold onto the hope that, some day, treatment using a peanut patch may be a drugstore trip away.

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About the Author

Adriana Barton is based in The Globe and Mail’s Vancouver bureau. Her article on growing up with counterculture parents is published in a McGraw-Hill anthology, right after an essay by Margaret Atwood. She wishes her last name didn’t start with B. More

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