New 'peanut patch' could help toddlers with allergies build tolerance

Almost 2.5% of American children suffer from a peanut allergy, a potentially life-threatening affliction that can make any restaurant or kitchen an unsafe space.

While there's no way to eliminate a peanut allergy, new research suggests a promising method to treat it. According to a study published in the New England Journal of Medicine, continuous use of a "peanut patch" can help desensitize toddlers with peanut allergies, increasing their tolerance for the legume over time.

The study was co-authored by Dr. Terri Brown-Whitehorn, an attending physician in CHOP's division of allergy and immunology. The Philly children's hospital was one of 51 sites where research was conducted from the summer of 2017 through April 2022. Brown-Whitehorn and her colleagues found that kids who wore the peanut patch for a few hours every day were able to consume higher doses of peanut protein a year later, making accidental exposures potentially less dangerous.

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"We've had kids who react to 1/50 of a peanut," Brown-Whitehorn said. "That to me is unbelievable, right? You had to give epinephrine. But if you take that same child and suddenly, they may have mild symptoms at 300 milligrams, which is a little bit more than a peanut, and you don't need to give them an epi? It's just exciting to me and for the families."

362 children between the ages of 1 and 3 were included in the trials. When the kids joined the study, doctors administered "food challenges," giving them small doses of peanut protein to gauge and record their reactions. Two-thirds of the toddlers then received the peanut patch for daily use while the other 118 took a placebo. About a year later, the children took the food challenges again.

The study found that 67% of the kids who used the peanut patch had a much higher peanut tolerance. Only 33.5% of those in the placebo group did.

"I think the exciting part of this study is that...for the two-thirds in which it worked, if the child has an accidental exposure, the child may be okay," Brown-Whitehorn said. "And before that, before wearing the patch for a year, they would have an allergic reaction for sure."

The patch, which is worn on the back, releases a freeze-dried peanut protein through the skin. While the children in the study initially wore it for three hours under medical supervision, families adjusted the length of time once they took it home. According to Brown-Whitehorn, "children can run, play (or) jump" while wearing the patch, as well as swim or take a bath. 

The results are promising, but the study is somewhat narrow in its subject pool. The team focused exclusively on toddlers, who tend to respond better, Brown-Whitehorn said, due to their more "malleable" immune systems. But children with very severe peanut allergies were excluded for their safety. The kids involved were mainly male (68.8%) and white (63.3%); only two Black toddlers were included in the trials.

"If you look at any food allergy study, it's a problem," Brown-Whitehorn said of participant diversity. "It's a big time commitment for the families, too. It's a big question, because you have to give your child something they're allergic to and know they may get really sick. So it's not taken lightly."

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