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The Pros and Cons of Oral Immunotherapy

One in 13 children and 32 million Americans live with food allergies, which requires constant vigilance. For many, accidental exposure, no matter how brief, can end in life-threatening anaphylaxis. The constant fear afflicting these individuals and their families is the driving reason behind the immunology community’s research into oral immunotherapy (OIT), a controversial treatment that can result in remission.

What is oral immunotherapy?

“With oral immunotherapy, we’re exposing people to the food that they’re allergic to starting in really tiny doses and then building up over weeks to months or even years,” Pamela A. Guerrerio, M.D. Ph.D., chief of the food allergy research unit at the National Institute of Allergy and Infectious Diseases, tells Florence Health.

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“The goal is to induce desensitization,” she continues. “That means that patients are able to tolerate a greater amount of the food after they’ve gone through therapy than they were able to tolerate before therapy.”

The process requires daily doses of the allergen for an extended period of time. Patients also must attend regular (often biweekly) visits with the clinician providing OIT to assess how they’re tolerating each dose level, according to the American Academy of Asthma, Allergy and Immunology. Home-monitoring for any doses taken outside a medical setting are another requirement.

What does the research around oral immunotherapy indicate?

Desensitization occurs in up to 80 percent of people while undergoing OIT, according to Dr. Guerrerio. What’s much less common is what experts call “sustained unresponsiveness” or “remission,” where a patient can tolerate the allergen even after stopping OIT.

Guerrerio estimates remission occurs in 20 percent of patients. “Most people need to be continually exposed to the food to maintain that state of unresponsiveness,” she adds. That said, success rates vary from trial to trial and food to food.

So far, there’s no clear answer to the question of how long a person must go through OIT to experience lasting effects — or how quickly after treatment the food allergy may return to its original state.

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“We think people need to take a [maintenance dose] daily,” Guerrerio says. “In some studies where patients stopped treatment and then were exposed to the food, a subset redeveloped their allergy after just one week off treatment.”

One of the most promising studies of OIT — analyzing the effects of Aimmune Therapeutics’ “peanut capsules” — will land in the Food and Drug Administration’s lap this September. A clinical trial of 500 kids with peanut allergies between 4 and 17 years old found two-thirds who took the pills could tolerate two nuts’ worth of peanut protein after a year of treatment. Participants who took the placebo did not fare so well.

The FDA will likely decide whether to approve the peanut pills, AR101, for consumer use early next year. As of August 2019, no methods of OIT (excluding clinical trials) have been approved by the FDA.

What are the pros and cons of OIT?

The controversy around OIT in part comes from the allergic reactions many patients have when going through the treatment. As Guerrerio explains it, “studies suggest people who undergo OIT have more reactions than people who practice strict avoidance.”

“In most cases, they’re mild to moderate — itchy mouth, maybe a few hives — but some people have severe reactions that require epinephrine, and they can happen unpredictably,” she continues. “Some patients will be on a stable, maintenance dose, and for various reasons, some of which we don’t understand, they will have a reaction at that dose.”

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Guerrerio adds that up to 20 percent of participants can’t complete treatment, usually due to gastrointestinal side effects, and as many as 5 percent develop eosinophilic esophagitis, when white blood cells called eosinophils accumulate in the esophagus. (Common symptoms of the former are abdominal pain, vomiting and cramping; with the latter, look for difficulty swallowing, vomiting and abdominal pain.) There’s also a psychological element to knowing you’re exposing yourself to a food you’re allergic to.

“It’s a trade-off,” Guerrerio says. “Most patients will be able to eat more of the food, but that comes at a cost of, in some cases, more allergic reactions. It’s the reassurance that you’re protected against accidental exposures versus knowing there’s a risk you’ll have a reaction to the treatment.”

What should clinicians tell patients interested in oral immunotherapy?

Right now, standard of care for food allergies is for patients to avoid the food and have epinephrine available in case of an accidental reaction — and not for clinicians practice OIT on their own.

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“It’s a safety issue. We know there’s frequent reactions, and we know some of those reactions can be severe,” Guerrerio states. “At this point, we’re advocating that it be done in the setting of research until we have a better sense of its safety and what measures need to be in place to ensure that.”

For patients or their parents interested in participating in a clinical trial, Guerrerio recommends visiting ClinicalTrials.gov or the Food Allergy Research & Education website for more information.

References:

The Current State of Oral Immunotherapy for the Treatment of Food Allergy, American Academy of Allergy, Asthma and Immunology.

AR101 Oral Immunotherapy for Peanut Allergy, The New England Journal of Medicine.

Eosinophilic esophagitis, Mayo Clinic.

Current Options for the Treatment of Food Allergy, US National Library of Medicine, National Institutes of Health.

Last updated on 8/20/2019

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