Almost all patients who develop gastrointestinal side effects from oral immunotherapy for severe food allergies develop some degree of esophageal eosinophilia, but that eventually resolves in most of them after a year of treatment, according to results of a pilot study that was to be presented at the American Academy of Allergy, Asthma & Immunology annual meeting. The AAAAI canceled the meeting and provided abstracts and access to presenters for press coverage.
Dr. Benjamin Wright
The findings may help identify biomarkers of persistent eosinophilia despite oral immunotherapy.
In January of this year the Food and Drug Administration approved oral immunotherapy (OIT), known as peanut allergen powder-dnfp, or peanut OIT (POIT), for severe food allergies. In an interview, lead study author Benjamin Wright, MD, of the Mayo Clinic, Phoenix, said OIT is a “promising proactive” treatment for food allergies. “But questions regarding the safety of immunotherapy remain,” he said. “About 30% of patients can develop GI side effects, including abdominal pain and vomiting; most concerning is that some patients develop eosinophilic esophagitis (EoE).”
The pilot study was a mechanistic substudy of 20 adult patients with immunoglobulin E–mediated peanut allergies enrolled in the phase 2 Peanut Oral Immunotherapy Safety, Efficacy and Discovery trial (POISED), with 15 randomized to treatment and the remainder to placebo. They had serial gastrointestinal biopsies at baseline (n = 20), 1 year (n = 7 treatment, 3 placebo) and 2 years (n = 7 treatment, 4 placebo) to evaluate eosinophils per high-power field (eos/hpf).
Baseline characteristics between the treatment and placebo groups were similar, with some having signs of preexisting disease. About 14% of them had clinically significant EoE, represented as a measure of more than 15 eos/hpf, Dr. Wright said. “One of the findings that was really fascinating to us was that all of the subjects had evidence of dilated intercellular spaces at baseline,” he said. “This indicates that all the subjects have some degree of epithelial barrier dysfunction before they start OIT.” Dilated intercellular spaces are a marker of inflammation.
Four patients in the treatment group had mild endoscopic findings at weeks 52 and 104, as did one patient on placebo, Dr. Wright said. A plot of eosinophil counts showed a peak at 52 weeks but near resolution at 104 weeks for all but one patient on OIT. “One of the most interesting trends that we noted was that, for most of patients, OIT-induced eosinophilia was transient and not fixed,” he said. “We noted a triangle pattern where tissue eosinophilia peaks and then resolves with the continuation of therapy.” EoE Histologic scoring system results followed a similar pattern in these patients, he added.
Also, results of the comprehensive GI Symptom Questionnaire, which assessed symptoms such as abdominal pain, difficulty swallowing, refusal to eat, and vomiting, showed that patient-reported GI symptoms did not correlate with tissue eosinophilia, Dr. Wright said. “To us, that suggests that perhaps eosinophils are not central to disease pathology or symptom development in these patients,” he said.
However, the findings validate that, in a small number of patients, OIT induces EoE, Dr. Wright said. He used a treadmill analogy to explain how OIT influences epithelial remodeling in some patients. “We’re constantly renewing our esophageal epithelium every 2 weeks, and when you challenge it with an antigen (i.e., OIT), the treadmill speeds up,” he said. “There may be some patients who will fall if the treadmill gets too fast, and they develop disease.”
He added, “Distinguishing someone’s fitness before they get on the treadmill is really going be a key moving forward in determining which subjects are good participants for OIT or how to dose OIT.”
Dr. Wright reported receiving grants from the Arizona Biomedical Research Consortium and Phoenix Children’s Hospital Foundation. Coauthors reported receiving grants from the National Institutes of Health and the Consortium for Food Allergy Research, as well as relationships with Aimmune Therapeutics, Regeneron Pharmaceuticals, Sanofi, Consortium for Food Allergy Research, DBV Technologies, Astellas, AnaptysBio, and Novartis.
SOURCE: Wright B et al. AAAAI, Session 2605, Abstract No. 259.