DESENSITIZATION ORAL IMMUNOTHERAPY

What is oral immunotherapy?

OIT is a process by which a food-allergic patient is given very small amounts of the food by mouth in increasing doses every day over a long period of time in order to achieve tolerance to that food. Tolerance is defined as no symptoms or only having mild symptoms if the food is ingested. OIT and is still investigational as the studies examining its safety and effectiveness have only been around for a few years. OIT is NOT FDA-approved as a treatment for food allergy. However, published evidence has been supportive.

Why do OIT?

The goal of OIT is to prevent the person who is allergic from having an allergic reaction if they are accidentally exposed to their allergen or possibly if they eat a larger amount of the allergen. Some patients can continue to tolerate the allergen even after stopping OIT while others must continue OIT in order to stay desensitized. Patients undergoing OIT will need to continue to avoid their allergen and always carry their epinephrine auto-injectors with them.

How effective is OIT?

Depends on the food. For example, in clinical trials for peanut allergy about 80% of patients were able to be desensitized, meaning they were able to tolerate more peanut following OIT than they did prior to OIT.

What are the risks/side effects of OIT?

There are expected allergic reactions during OIT, the most severe tend to be on the initial escalation day and the build-up phase but can happen at any time even after being on maintenance for years. Reactions range from mild (runny nose, itchy eyes/mouth, hives around the lips, nasal congestion, etc.) to severe (shortness of breath, throat swelling, diarrhea, stomach pain, loss of consciousness, generalized hives, anaphylaxis) and death (theoretically) although this has not been reported for OIT that we are aware of.

There have also been a few reports of patients who are receiving OIT developing eosinophilic esophagitis, a condition characterized by inflammation of the esophagus and difficulty swallowing. Overall, about 10-20% of patients drop out from OIT, usually due to side effects like abdominal discomfort.

What does the schedule look like for OIT?

• Initial escalation day: this day takes about 6-7 hours and extremely small amounts of food protein is introduced by mouth (in a safe food that patient brings such as applesauce or yogurt) in increasing doses every 30 minutes. We find a dose at which the patient has very little or no symptoms and we use this as the home dose. Patient is to purchase an acceptable scale to measure doses at home, pick up medications to treat reactions, and have a journal to record daily doses, reactions, etc. All questions and details are addressed at this time including self-measurement of doses.
• Build-up phase: after initial escalation day, patient will continue this dose daily at home while eliminating all other ingestion of the food in the diet unless discussed with a provider. S/he will come back to the office every 1-4 weeks to do a dosage increase until we are able to reach a maintenance dose. If the patient is less than 3 years old, the maintenance dose will be lower.
• Maintenance phase: Once the maintenance dose is tolerated, the patient continues to ingest that dose of food daily at home in the maintenance phase and comes back to the office every 4-6 months to do a food challenge to see if s/he is able to tolerate a higher dose of that food. Goal of the maintenance phase is to continue the highest tolerated dose daily for the longest possible amount of time. We aim for at least 3 years but may recommend a longer duration depending on the clinical scenario. Some patients, after being on OIT for a few years, exhibit signs that they will tolerate that food indefinitely after stopping OIT. Others will need to continue maintenance phase to maintain tolerance. Evidence points to children under 3 years old benefiting more from OIT and having a higher chance of having tolerance after stopping OIT than older patients.

What is my responsibility as a patient and/or parent?

The desensitization process is laborious and requires vigilance, honesty, and determination from the patient and family involved. It can be a daunting process, but many believe the result is worth it.