Children with peanut allergies treated with peanut oral immunotherapy for 3 years can tolerate increasingly higher exposures to peanuts. But avoidance of peanut-protein exposure for just a single month after the treatment leads to rapid and substantial decreases in tolerance, findings from a small study show.
The findings “underscore the fact that the desensitization achieved with peanut oral immunotherapy is a transient immune state,” report the authors of the study, published in December in The Journal of Allergy and Clinical Immunology: In Practice.
Therefore, “adherence to dosing [in peanut immunotherapy] is very important, and clinicians should expect a decline in tolerance with lapse in dosing,” first author Carla M. Davis, MD, director of the Texas Children’s Hospital Food Allergy Program at Baylor College of Medicine, Houston, told this news organization.
Oral immunotherapy, involving small exposures to peanut protein to build up desensitization, has been shown to mitigate allergic reactions, and, as reported by this news organization, the first peanut oral immunotherapy drug recently received approval from the U.S. Food and Drug Administration.
However, current approaches involve very low daily exposure of about 300 mg of peanut protein, equivalent to only about one to two peanuts, and research is lacking regarding the maximum tolerated doses, as well as on how long the tolerance is sustained if maintenance therapy is discontinued. “For the peanut-allergic population that would like to eat more than 1-2 peanuts, an achievable dose is currently unknown,” the study authors write. “The critical question, of the maximum tolerated dose achieved after POIT, has not been answered.”
To evaluate those issues in their phase 2 study, Dr. Davis and her colleagues enrolled 28 subjects between the ages of 5 and 13 with a diagnosis of eosinophilic esophagitis and peanut allergy.
The treatment protocol included a 1-year buildup phase of oral immunotherapy, followed by a 2-year daily maintenance phase with a dose of 3,900 mg of peanut protein.
After consenting, 11 patients dropped out of the study due to a lack of interest, and two more withdrew after failing to tolerate their first dose, leaving 15 who started treatment in the study, with a mean age of 8.7 years (range, 5.2-12.5 years), and 47% female.
Twelve patients reached the maintenance dose of 3,900 mg over a median of 13 months, and double-blind, placebo-controlled peanut challenges showed that, on average, their mean maximum cumulative tolerated dose after 12 months increased by 12,063 mg (P < .001), and the mean dose triggering a reaction increased by 15,667 mg.
Of the 12 patients, 11 (91.7%) were able to successfully tolerate at least 10,725 mg after 12 months of treatment, and six patients (50.0%) successfully tolerated at least 15,225 mg.
Two patients were able to tolerate up to the maximum cumulative target dose of 26,225 mg, equivalent to more than 105 peanuts.
“The ability to tolerate [greater than] 100 peanuts following peanut oral immunotherapy has never before been demonstrated and gives insight into the potential for food oral immunotherapy to be utilized in a subset of patients who have an immunologic phenotype accepting of this therapy,” the authors write.
“Understanding the risk of ingestion of peanut protein higher than the prescribed peanut oral immunotherapy maintenance dose will improve the safe, practical use of [the therapy],” they add.