Sublingual Immunotherapy Appears Viable in Treating Peanut Allergies in Kids

Peanut sublingual immunotherapy (SLIT) achieved clinically significant desensitization to peanut allergens in the majority of children in an open-label, prospective study.

Among 47 kids who completed therapy and the 48-month double-blind, placebo-controlled food challenge, 70% achieved clinically significant desensitization (successfully consumed dose [SCD] >800 mg), and 36% achieved full desensitization (SCD 5,000 mg), reported Edwin H. Kim, MD, MS, of the University of North Carolina School of Medicine in Chapel Hill, and co-authors.

The mean SCD of peanut protein during the food challenge increased from 48.4 mg at baseline to 2,723 mg after 48 months (P<0.0001), and desensitization lasted more than 17 weeks following treatment discontinuation, they noted in the Journal of Allergy and Clinical Immunology.

As of 2021, it has been estimated that about 4.6 million adults in the U.S. have some form of peanut allergy, with 800,000 having developed the allergy during adulthood. Approximately 200,000 people in the U.S. are sent to the emergency department following a food-related allergic reaction each year.

“The typical approach of strict allergen avoidance has been shown to greatly reduce the frequency of allergic reactions; however, over time most patients experience accidental ingestions with unpredictable and sometimes severe symptoms,” Kim and team wrote. “Furthermore, strict allergen avoidance has led to the unintended consequence of a significant decrease in quality of life driven by factors such as anxiety, social isolation, restricted daily activities, and financial burden. Immunotherapy has been the best studied approach to treatment with numerous positive studies of oral immunotherapy (OIT) leading to the recent regulatory approval of the first product for peanut OIT.”

In the study, peanut skin prick testing for the per-protocol population was significantly decreased by 12 months of treatment and remained this way over the course of treatment, from a mean wheal size of 16.5 mm at baseline to 9.1 mm after 48 months (P<0.0001).

Peanut-specific immunoglobulin E levels had significantly decreased by 24 months and through the duration of treatment, from a mean baseline level of 213.0 kU_A/L to 60.7 kU_A/L after 48 months (P<0.0001), following an initial increase from baseline to 6 months. Peanut-specific immunoglobulin G4, however, increased from an average of 0.8 mg/L at baseline to an average of 20.6 mg/L after 48 months (P<0.0001).

Mean percentage of CD63+ basophils decreased from baseline at both the 10 ng/mL dilution, which was significant throughout the 48 months, and the 1 ng/mL dilution, which was significant at the 24- and 48-month time points.

T_H2 cytokine levels after peanut stimulation also decreased over time, with average IL-4, IL-5, IL-13, and IFN-gamma levels significantly reduced over 48 months.

“With the goal of peanut allergy treatment increasingly focused on protection from accidental ingestions of peanut, our data for peanut SLIT supports a treatment response in the majority of patients that importantly appears to be able to withstand lapses in therapy of up to several weeks,” Kim and colleagues wrote.

“When considering that tolerance does not appear likely with food immunotherapy and that treatment is likely to be required long-term if not indefinitely, these results demonstrating the feasibility and safety of keeping up the daily peanut SLIT regimen for multiple years take on particular importance,” they added.

For this study, 54 peanut-allergic children ages 1 to 11 years (mean age 7.1, 63% boys, 90.7% white) were treated with open-label 4-mg peanut SLIT for 48 months, and 47 completed therapy. At baseline, 70.4% of children reported atopic dermatitis, 59.3% reported allergic rhinitis, 40.7% reported asthma, and 27.8% reported other food allergies. Dosing compliance was high, with 97.6% of doses administered.

Desensitization after SLIT was assessed by a 5,000-mg double-blind, placebo-controlled food challenge. A randomly assigned avoidance period between 1-17 weeks was followed by a food challenge. Skin prick testing, immunoglobulins, basophil activation testing, TH1, TH2, and IL-10 cytokines were measured longitudinally. Safety was assessed through patient-reported diaries.

Symptoms were reported after 4% of home-administered doses. Lip swelling and oropharyngeal itching were the most common symptoms, occurring with 3.7% of doses. Belly pain, vomiting, diarrhea, and skin symptoms were reported with 0.1% of doses. Three participants withdrew as the result of abdominal reactions or food aversion. While 0.14% of the administered doses required the use of antihistamines, epinephrine was not given at any point during the course of the study.

Kim and team noted that there was no blinding of the treatment or avoidance phases of the study, which was a limitation. Children can also “spontaneously outgrow” a peanut allergy, though the authors said this was unlikely in their cohort.