New Therapy for Food Allergy Builds Tolerance Through Exposure

Researchers are applying an old principle to a new treatment for food allergy -- fight fire with fire.

The technique is called oral immunotherapy, and it essentially attempts to build a child's tolerance by gradually exposing them via oral ingestion to the food proteins that typically trigger a severe allergic reaction, or anaphylactic shock.

"The purpose of immunotherapy is to change your immune response over a period of months to years," said Dr. Wesley Burks, chief of pediatric allergy and immunology at Duke University and a pioneer in oral immunotherapy. "So you start off being allergic and at the end of that therapy, you are no longer allergic."

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Right now, the treatment is only available in clinical trials because it is experimental. While some allergists may offer it in their practices, those investigating the treatment caution against routinely attempting this approach because doing so can have unpredictable, and sometimes dangerous, results.

Still, many allergists and patients are banking on the promise of oral immunotherapy because there are so few treatment options for food allergy aside from avoidance and keeping injectible epinephrine handy at all times.

Oral immunotherapy involves first giving the child a very small dose -- as little as a thousandth of a percent -- of the protein he or she is allergic to, whether it's egg, peanut or milk.

The physician will then gradually increase the dose, usually over a period of weeks. In the meantime, the child takes a "maintenance" dose of the allergen at home every day.

Early results of one of the first randomized controlled trials -- the gold standard of evidence-based medicine -- of oral immunotherapy for peanut allergies were presented last month at the American Academy of Allergy, Asthma, and Immunology meeting in New Orleans.

Burks and his team found that after 48 weeks of oral immunotherapy food-allergic children could tolerate eating the equivalent of 20 peanuts.

Children who were on a sham treatment, or a placebo, could only eat the equivalent of 1.5 peanuts.

"Certainly the early studies indicate that it is promising," Burks said. However, he warned that the research "isn't quite there yet."

Exposure Treatment Can Be Unpredictable

Dr. Hugh A. Sampson, of the Jaffe Food Allergy Institute at Mount Sinai Medical Center in New York who is involved in a randomized controlled trial of oral immunotherapy for egg allergy, said the treatment can bring unpredictable risks.

"Even under very conservative protocols," he said, "we still see adverse reactions."

Most reactions are mild -- abdominal pain, vomiting, swelling -- but trials have reported cases of anaphlaxis, some in the physician's office while upping the dose, others at home while taking maintenance dosing.

"We especially don't want parents trying this at home because kids can have these fairly severe reactions," Sampson said.

The next step, he said, is to investigate which will be least likely to have these adverse reactions, as well as which patients will benefit most from the treatment.

Another issue to consider is whether children will maintain their tolerance once they've been off oral immunotherapy for a longer period of time.

Given the amount of research that still needs to be done, Burks says it will likely take several years before the treatment is widely available.

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