Analysis Shows Small Rate of Eosinophilic Esophagitis in Peanut Immunotherapy Trial

The eosinophilic esophagitis responded to treatment or resolved after the peanut oral immunotherapy stopped.

The rate of developing eosinophilic esophagitis (EoE) during a trial for a peanut oral immunotherapy was about 1%, according to a report published last month.

The EoE responded to treatment or resolved after the peanut oral immunotherapy stopped. EoE is a chronic immune-inflammatory disease triggered by food and/or environmental allergens, and its onset has also been reported in patients using oral immunotherapy for not only peanut food allergy but also milk and egg allergy.

The product, Palforzia (peanut Arachis hypogaea allergen powder-dnfp), was approved 2 years ago by the FDA for use in children 4 to 17 years old. It is contraindicated in patients with a history of EoE and should be discontinued if EoE develops taking it.

Data for all participants in the clinical trial program for Palforzia were reviewed to identify those with EoE as of December 15, 2018, and calculate overall incidence. Researchers also sought to outline baseline clinical characteristics, symptoms, and treatment.

The clinical trial program included 2 phase 2 trials and 6 phase 3 trials; 1217 participants aged 4 to 55 years received the therapy. Of those, 62 patients withdrew from the studies due to gastrointestinal symptoms and 28 were referred for gastroenterology evaluation.

Of the 28 sent for further evaluation, 17 underwent esophagogastroduodenoscopy (EGD), with 12 receiving a diagnosis of EoE, yielding an EoE incidence of approximately 1%.

The overall exposure-adjusted EoE event rate was 0.9 per 100 patient-years.

Most EoE cases occurred in children, and most of those were male. There was 1 EoE case in an adult female.

Eleven of the 12 had asthma and 10 of the 12 had allergic rhinitis. Other atopic diseases were other food allergies (n = 9) and atopic dermatitis (n = 5).

Common EoE symptoms included globus sensation, gastroesophageal reflux, regurgitation, vomiting, and postprandial abdominal pain.

It is unknown whether there was a subset of patients who would have had transient esophageal eosinophilia or developed EoE but did not undergo EGD.

In 11 cases, symptom improvement or resolution occurred within 12 days to 12 months of ending peanut oral immunotherapy and starting EoE therapy, most with a proton pump inhibitor with or without a topical corticosteroid (fluticasone and/or budesonide).

Ten cases were considered related to Palforzia treatment (4 had a history of chronic or recurrent gastrointestinal symptoms) and 2 were considered unrelated, as gastrointestinal symptoms may have been present before starting therapy.

Three cases were classified as mild, 7 moderate, and 2 severe; none were considered serious. The median (range) Palforzia dose at EoE diagnosis was 160 mg (12-950 mg).

The 1% of patients who did develop EoE did not include 5% of participants who ended treatment because of gastrointestinal symptoms that were not further investigated.

The incidence of EoE may be underestimated, the researchers said.

In addition, because the data came from multiple clinical trials, "it cannot provide the same quality of evidence as a true longitudinal incidence study of EoE," the authors noted. In addition, the low rate of EoE may have been affected by the fact that participants were excluded from the trials if they already had a history of gastrointestinal issues.


Nilsson C, Scurlock AM, Dellon ES, et al. Onset of eosinophilic esophagitis during a clinical trial program of oral immunotherapy for peanut allergy. J Allergy Clin Immunol Pract. 2021;9(12):4496-4501. doi:10.1016/j.jaip.2021.07.048