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Therapy to suppress peanut allergies is reported

By taking small but increasing doses of the food, five children can now freely eat items containing peanuts, an allergist says in presenting the results of two clinical trials.

March 16, 2009|Melissa Healy

After years of frustration, allergists meeting in Washington proclaimed a small but significant victory against life-threatening peanut allergies.

Five children, long urged to avoid peanuts like the plague, today tote peanut-butter-and-jelly sandwiches in their lunch boxes, blithely share candy with friends and accept snacks at other people's homes without quizzing their hosts on the treats' ingredients.

The children appear to have lost their allergies, said Dr. Wesley Burks, a Duke University pediatric allergist who presented the results of two clinical trials Sunday at a meeting of the American Academy of Allergy, Asthma and Immunology.

The unpublished trials tested whether peanut-allergic patients could be helped to tolerate peanuts by consuming tiny but increasing doses of the food, which induces hives, itching or swelling and is responsible for about half of the 150 annual deaths associated with food allergies in the United States. The studies are the first in a series of promising efforts to push back this dangerous, and growing, allergy.

As many as 3 million Americans have an allergy to peanuts, and usually also to tree nuts such as almonds and walnuts. The percentage of U.S. children with a food allergy jumped 18% in the decade leading to 2007, according to the Centers for Disease Control and Prevention, and there has been a fourfold increase in children's hospitalizations for food allergies in recent years. Researchers have puzzled over the cause of this rapid rise; some have suggested that childrens' dwindling exposure to dirt, soil and animals has driven the increase.

Though the studies are small and preliminary, Burks said the group planned to enroll more children in the research, and he hoped that within two to three years, the first of several treatments for peanut allergies will be available to physicians.

"We're encouraged," said Robert Pacenza, executive director of the Food Allergy Initiative, a patient group active in promoting research and educating the public about the dangers of food allergies. Though only five children have so far had a seemingly complete reversal of their allergy, that's five that have never been seen before, he said.

In the studies, conducted by a joint team of researchers from Duke University Medical Center and the Arkansas Children's Hospital Research Institute, children started on the equivalent of 1/1,000th of a peanut and progressively worked their way up.

In the first study, 33 highly allergic children underwent the so-called oral immunotherapy treatment. Burks reported on nine who had been followed for 2 1/2 years. Five had weathered several food challenges -- eating a substantial helping of peanuts -- without incident, under the eyes of a researcher armed with a syringe full of epinephrine to counter any sudden reaction that might occur.

All five started the trial with slightly lower allergic sensitivity than the average subject. They have been allowed to discontinue daily therapy, though their peanut intake is still monitored, as are immune reactions that might signal a return of their peanut sensitivity.

Burks said that he was unsure how long the effect would last but that the five children were the first ever to exhibit "long-term tolerance" of peanuts after having been diagnosed as allergic.

"They're eating peanut candy, peanut-butter-and-jelly sandwiches, whatever they want," Burks said.

The second study, though very small, is of a design that is considered to be the gold standard of research. In it, 18 subjects were divided into two groups, one of which got oral immunotherapy and the second, a placebo. The children were fed small but growing portions of peanut protein and were periodically tested to see whether the dose could be increased without reaction.

In Burks' report on the 10 children who had been in treatment longest (from six to eight months), five given the placebo treatment could tolerate the equivalent of about one peanut before experiencing allergic symptoms. All five on oral immunotherapy could eat the equivalent of 13 to 15 peanuts without distress.

The studies, which were the buzz of the allergists' conference this year, are among the first products of a new Food Allergy Research Consortium, established by the National Institutes of Health in 2005 with a $22-million grant.

Some of the consortium's other early findings received their first public airing at the allergy meeting. A study using mice found that a traditional Chinese herbal medicine showed promise in reducing allergic reactions to peanuts; another trial showed that applying small amounts of peanut extract on the skin appeared to build tolerance in peanut-allergic mice.

Other approaches promise more advanced therapies down the road. One -- expected to begin human trials this year -- is a peanut allergy vaccine, designed to trick the human immune system into giving up its defense against peanuts.

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