Oral immunotherapy (OIT) is an effective medical treatment for allergic patients, designed to reduce the severity of allergic reactions and improve tolerance to specific allergens. The therapy involves gradually introducing tiny amounts of the allergen to desensitise their immune system and ultimately increase their threshold for triggering an allergic reaction. OIT has gained popularity recently, becoming a common treatment option for patients with severe food allergies.

The triggers for EoE are Non-IgE (non-allergic) delayed hypersensitivity responses however, people with EoE can commonly live with allergies (IgE) and carry EPI Pens or suffer from airborne allergies such as house dust-mite and tree pollen, explains Immunologist Dr Efrem Eren in our video - Allergy and EoE What's the Connection.

However, there is an ongoing discussion on the potential risks of this therapy, particularly its association with eosinophilic deceases.

A new study, "Oral Immunotherapy and Risk of Eosinophilic Esophagitis in Children: 15 Years' Experience", was published in the January 2023 issue of Gastroenterology and Nutrition by Morales-Cabeza et al.  

Researchers conducted a retrospective study over 15 years with 637 OITs performed. The study highlights the need to detect eosinophilic oesophagitis (EoE) before and after OIT, as it appeared to be an uncommon but significant adverse occurrence. 

Methods

During the years (2005–2020), researchers assessed the prevalence of EoE in a sizable cohort of children who received OIT at their facility, focusing on any clinical, endoscopic, or histologic variations depending on the food used for the procedure. 

They performed 637 OITs (277 cow's milk (CM-OIT), 322 egg-OIT, and eight peanut-OIT). 

The goal was to determine if there were any clinical, endoscopic, or histologic differences depending on the food used for the procedure. Researchers found some increased incidence of EoE diagnosis in children treated for cow's milk allergies compared to those who received egg-OIT. 

Results

The study found the highest prevalence in those who received OIT for cow's milk allergies (3.9%) than egg-OIT (2.2%) and confirmed diagnosis of EoE in 17 children (2.8% of patients). 

Symptoms of EoE appeared after the build-up phase of OIT, with dysphagia, stomach discomfort, and choking being the most common. 

The study informs that one-third of the patients had minor EoE-suggestive symptoms before starting the OIT and emphasises the importance of early screening for EoE before and after OIT using validated questionnaires and follow-ups, as symptoms can occur even years after OIT.

What Allergists Think About Oral Immunotherapy and Eosinophilic Esophagitis 

At the BSPGHAN Annual Meeting, Dr Nandinee Patel from Imperial College London presented a review of studies that support the conclusions of a recent study mentioned earlier.

In total, 110 studies were examined, involving 6366 patients:

• 32% of patients experienced abdominal pain (similar rates across egg, peanut, and milk allergies)
• 12% reported vomiting (mostly in peanut and egg allergies compared to milk: 17% vs 1%)

Out of the 82 studies that reported reasons for discontinuing treatment:

• 4.7% suggested possible eosinophilic esophagitis (EoE) symptoms

Among the 18 studies that conducted biopsies:

• 5.3% confirmed EoE (some patients continued OIT)

However, Dr Patel says OIT allows allergic patients more food freedom and improves social interactions and overall quality of life. 

OIT has massively helped me with my future career and given me the confidence when eating out. I can now eat out at restaurants with family and friends, - says one of Dr Patel's patients. 

Key Insights from Dr Patel's Presentation In Pre and Post-OIT Care

Dr Patel suggests balancing the risks and goals of OIT before the procedure and offers steps for improving the outcomes. 

1. Standardisation of symptom reporting and capture of long-term outcomes.
2. Consensus on criteria for pre-investigation and post-investigation. 
3. Research on the management options once patients present with EoE signs.
4. Pre-OIT assessments - early screening of possible EoE symptoms.
5. Development and use of non-invasive biomarkers (string tests, cytosponge, peripheral blood eosinophil progenitors, specific T-cell activation).
6. Follow-up of all patients, whether they continue or stop OIT, especially if they have gastrointestinal symptoms.
7. Providing EoE treatment when necessary.

Take Away For Patients and Healthcare Professionals

Allergies are common in those with EoE, and the allergy symptoms may not be present or be identified before OIT. The findings from both study reviews emphasise the significance of conducting early screenings before initiating OIT and maintaining long-term follow-ups with patients, as the future outcomes of EoE in OIT remain unclear.

References

Cafone J., Capucilli P., Hill DA, Spergel JM. Eosinophilic esophagitis during sublingual and oral allergen immunotherapy. Curr Opin Allergy Clin Immunol. 2019 Aug; 19 (4): 350-357

A study "Oral Immunotherapy and Risk of Eosinophilic Esophagitis in Children:15 Years' Experience".

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