To examine the effectiveness and safety of peanut oral immunotherapy (POIT) after 1 year of maintenance in preschool-aged children.

In the study, researchers included 161 patients aged 9 to 70 months who successfully completed 1 year of maintenance POIT and were eligible for follow-up oral food challenge (OFC). The inclusion criteria were having a history of objective reaction to peanut and a positive test result (either a skin-prick test [SPT] or peanut-specific immunoglobulin E [ps-IgE]) or at least 1 objective reaction with dosing during build-up, along with a predetermined ps-IgE level and SPT wheal size.

Preschoolers enrolled in the study were given gradually increasing peanut protein doses over 16–22 weeks at clinic visits, building up to a maintenance dose of 300 mg. The children then ingested 300 mg of peanut protein daily for a year. After ∼12 months, the participants were invited to participate in a follow-up peanut OFC. SPT and/or ps-IgE were obtained at baseline and selectively throughout the maintenance and follow-up OFC visits. Symptoms of allergic reactions occurring were recorded and graded 1 to 5.

Of the patients who received a year of maintenance therapy and underwent follow-up OFC (n = 117), 92 (78.6%) tolerated a cumulative dose of 4000 mg peanut protein without any symptoms, and 115 (98.3%) tolerated at least 1000 mg. The dose tolerated had increased on average by 3969 mg in those with a negative follow-up OFC and by 3376 mg in those with a positive follow-up OFC. SPT wheal size was also significantly decreased after a year regardless of follow-up OFC result; however, the decrease in ps-IgE was not statistically significant. Those with reactions at the follow-up OFC had either grade 1 (14.5% of all who underwent OFC), grade 2 (6%), or grade 3 (0.85%). No one had a grade 4 or 5 reaction. Of the 124 patients with safety outcomes analyzed during maintenance therapy, 111 (89.5%) were symptom-free during POIT dosing, 10 (8.1%) had grade 1 reactions, 3 (2.4%) had grade 2 reactions, and only 2 (1.6%) required epinephrine for POIT dosing reactions.

POIT is effective for preschoolers, protecting against at least 1000 mg peanut protein exposure after one year of maintenance therapy in 98.3% of children and allowing consumption of up to 4000 mg in 78.6%. It is also safe during maintenance, with nearly 90% of children symptom-free during maintenance dosing.

POIT has emerged as a patient-preference–sensitive option to increase tolerance to peanut protein and protect against accidental exposure. Previous studies have revealed that increasing the peanut threshold to 1000 mg provides 99% protection from accidental exposures, and commercial POIT product is now approved in children 4 to 17 years old. This is the first real-world study revealing that the majority of preschoolers (98.3%) are able to tolerate 1000 mg after a year of POIT maintenance therapy. Mounting evidence suggests POIT may be safer and more effective when initiated at younger ages, likely because of a milder allergic phenotype, less patient aversion, and opportunity for better adherence from close parental supervision. Preschool POIT is a promising disease-modifying intervention that, in the context of shared decision-making with an experienced pediatric allergist, is likely to dramatically improve health and economic outcomes for patients and families.