Food Allergy Immunotherapy

Right now, there's no Food and Drug Administration-approved medical therapy to treat food allergies. The only treatment is one families and kids affected know all too well: avoid. Read every label. Talk to the school. Ask the waiter. Better yet, ask the waiter to get the chef.

That's about to change.

Current food allergy testing

At Children's Hospital Colorado's Allergy and Immunology Center, pediatric nurse-practitioner Lisa Hiers, MSN, is running food challenges. Her partner for the day, pediatric nurse Trey Bemis, RN, just ducked into room 12 to check on 10-month-old Izad,* who, about 20 minutes ago, ate 0.2 grams of peanut powder mixed into apple sauce.

"He's maybe got a little redness around his mouth and above his eyebrow," Trey reports. "Want to check it out?"

In the challenge room, Izad's mom pulls him into her lap so Lisa can examine his face. She lifts his shirt to check his belly and his back. He has eczema and had a positive peanut skin test, so a peanut allergy is suspected. But there's only one way to be sure.

"The most reliable test is whether you can eat that food without a reaction," says David Fleischer, MD, Director of the Allergy and Immunology Center. "We don't want kids to have to avoid foods unnecessarily. We want to get as many foods as possible into their diet, so if there's no history of ingestion with a reaction, we do food challenges."

If Izad has an allergic reaction, Lisa and Trey will end the challenge knowing exactly how much peanut it took to provoke it. Most of the time, because the dose amounts start so small, they can stop a reaction with a dose of antihistamine, sometimes epinephrine. But each challenge room is set up for worst-case scenarios: all the equipment necessary to treat a severe reaction, plus direct nurse supervision at all times.

Izad looks good, though, so Trey mixes another 0.5 grams of peanut powder into the apple sauce. Then he walks down to room 10 to give a gram of peanut butter to 8-year-old Noah,* who, like Izad, had a positive peanut skin test as a baby but has never actually eaten the food.

Treating peanut allergies in children

Back when Noah was Izad's age, the conventional wisdom was to keep kids away from peanut or tree nuts until at least 3 years old. That wisdom was effectively reversed with the publication of a 2015 study that followed more than 600 babies at high risk for peanut allergy for more than 5 years.

Half of the kids got peanut starting at 4 to 11 months. The other half avoided it for 5 years. By the end of that time, 17% of the kids who avoided peanut developed an allergy. Of the kids who got peanut, that figure was just 3%.

"So the thought is that, when you introduce these foods earlier into the GI system, that induces tolerance," says Dr. Fleischer. "The gut is the largest immune system in the body. You want to get it when it's less mature and won't see these proteins as potentially dangerous."

Why some kids' immune systems see proteins like peanut and egg as threats remains a mystery. But researchers do know that early-onset, persistent eczema correlates with food allergies, and for kids like Izad, the answer may be that some babies' first introduction to those proteins comes the wrong way: food particles in household dust absorb through the broken skin of eczema, causing kids to become sensitized to the protein before they ever eat it.

That's the theory, but what's been proven is that, just as immune systems can become sensitized to allergens, they can be desensitized as well.

Food desensitization and immunotherapy

Researchers like Dr. Fleischer and Matthew Greenhawt, MD, Director of the Center's Challenge and Research Unit, have been studying the idea of immune desensitization for well more than a century. But it's only in the last few decades that the work has had a benefit for kids with food allergies — through clinical trials with food immunotherapy products that will likely soon hit the market.

Dr. Fleischer served as a global primary investigator for one of the most impactful of those trials, and much of the actual testing took place in the Allergy and Immunology Center's 12 rooms dedicated specifically to clinical research. With the final phase of those trials wrapped up, he thinks two products are likely to be FDA-approved by the end of this year.

"This patch and protein powder will be the first actual treatments for peanut allergy to get approved," he says. "And we'll probably be starting final phase trials with a milk patch this year. It's important to us to be able to offer our patients the ability to participate in these trials."

The patch, which began its life as a potential new type of diagnostic test for milk allergy until researchers found it had desensitizing properties, delivers a constant dose of 250 micrograms of peanut protein through the skin (that's about one thousandth of a peanut). Patients start with several hours and work up to all-day application. The peanut protein powder therapy starts with a dose of half a milligram and works up to the equivalent of about one peanut daily.

Both are relatively safe when used in care of an allergist, and both are proven to desensitize — though neither is a cure, exactly.

Proactive food allergy management

"Parents of these kids want to be proactive," says Dr. Fleischer. "They don't want to wait for their kids to outgrow their allergies or potentially have a severe, life-threatening reaction. And most of these kids don't care if they ever eat a peanut butter and jelly sandwich. They want some protection from that severe reaction, and that's what these treatments are designed to do."

That's the case for Noah, who, as it turns out, does not care for peanut butter. Indeed, says Lisa, many of the kids who undergo food challenges don't like the foods they've been avoiding. The texture is odd. They're not used to it.

But it also turns out, in the end, that Noah isn't allergic to peanut. Neither is Izad. That's the case for many of the 50 to 75 patients who undergo food challenges at the Center each week. Some outgrow their allergies. Some never had one at all. But for the kids who do have them, the Center's ongoing allergy research offers a lot of hope — now and in the future.

"We want to give our patients and families choices," says Dr. Fleischer. "We're looking at treatments for other food allergies, including allergy shots and vaccines. This is just the first wave."

* Name changed to protect patient privacy.