Sustained unresponsiveness to peanut in subjects who have completed peanut oral immunotherapy.

BACKGROUND: Although peanut oral immunotherapy (OIT) has been conclusively shown to cause desensitization, it is currently unknown whether clinical protection persists after stopping therapy. OBJECTIVE: Our primary objective was to determine whether peanut OIT can induce sustained unresponsiveness after withdrawal of OIT. METHODS: We conducted a pilot clinical trial of peanut OIT at 2 US centers. Subjects age 1 to 16 years were recruited and treated for up to 5 years with peanut OIT. The protocol was modified over time to permit dose increases to a maximum of 4000 mg/d peanut protein. Blood was collected at multiple time points. Clinical end points were measured with 5000-mg double-blinded, placebo-controlled food challenges once specific criteria were met. RESULTS: Of the 39 subjects originally enrolled, 24 completed the protocol and had evaluable outcomes. Twelve (50%) of 24 successfully passed a challenge 1 month after stopping OIT and achieved sustained unresponsiveness. Peanut was added to the diet. At baseline and the time of challenge, such subjects had smaller skin test results, as well as lower IgE levels specific for peanut, Ara h 1, and Ara h 2 and lower ratios of peanut-specific IgE/total IgE compared with subjects not passing. There were no differences in peanut IgG4 levels or functional activity at the end of the study. CONCLUSIONS: This is the first demonstration of sustained unresponsiveness after peanut OIT, occurring in half of subjects treated for up to 5 years. OIT favorably modified the peanut-specific immune response in all subjects completing the protocol. Smaller skin test results and lower allergen-specific IgE levels were predictive of successful outcome.

A randomized controlled study of peanut oral immunotherapy: clinical desensitization and modulation of the allergic response.

BACKGROUND: Open-label oral immunotherapy (OIT) protocols have been used to treat small numbers of patients with peanut allergy. Peanut OIT has not been evaluated in double-blind, placebo-controlled trials. OBJECTIVE: To investigate the safety and effectiveness of OIT for peanut allergy in a double-blind, placebo-controlled study. METHODS: In this multicenter study, children ages 1 to 16 years with peanut allergy received OIT with peanut flour or placebo. Initial escalation, build-up, and maintenance phases were followed by an oral food challenge (OFC) at approximately 1 year. Titrated skin prick tests (SPTs) and laboratory studies were performed at regular intervals. RESULTS: Twenty-eight subjects were enrolled in the study. Three peanut OIT subjects withdrew early in the study because of allergic side effects. During the double-blind, placebo-controlled food challenge, all remaining peanut OIT subjects (n = 16) ingested the maximum cumulative dose of 5000 mg (approximately 20 peanuts), whereas placebo subjects (n = 9) ingested a median cumulative dose of 280 mg (range, 0-1900 mg; P < .001). In contrast with the placebo group, the peanut OIT group showed reductions in SPT size (P < .001), IL-5 (P = .01), and IL-13 (P = .02) and increases in peanut-specific IgG(4) (P < .001). Peanut OIT subjects had initial increases in peanut-specific IgE (P < .01) but did not show significant change from baseline by the time of OFC. The ratio of forkhead box protein 3 (FoxP3)(hi): FoxP3(intermediate) CD4+ CD25+ T cells increased at the time of OFC (P = .04) in peanut OIT subjects. CONCLUSION: These results conclusively demonstrate that peanut OIT induces desensitization and concurrent immune modulation. The current study continues and is evaluating the hypothesis that peanut OIT causes long-term immune tolerance.

Sublingual immunotherapy for peanut allergy: clinical and immunologic evidence of desensitization.

BACKGROUND: There are no treatments currently available for peanut allergy. Sublingual immunotherapy (SLIT) is a novel approach to the treatment of peanut allergy. OBJECTIVE: We sought to investigate the safety, clinical effectiveness, and immunologic changes with SLIT in children with peanut allergy. METHODS: In this double-blind, placebo-controlled study subjects underwent 6 months of dose escalation and 6 months of maintenance dosing followed by a double-blind, placebo-controlled food challenge. RESULTS: Eighteen children aged 1 to 11 years completed 12 months of dosing and the food challenge. Dosing side effects were primarily oropharyngeal and uncommonly required treatment. During the double-blind, placebo-controlled food challenge, the treatment group safely ingested 20 times more peanut protein than the placebo group (median, 1,710 vs 85 mg; P = .011). Mechanistic studies demonstrated a decrease in skin prick test wheal size (P = .020) and decreased basophil responsiveness after stimulation with 10(-2) µg/mL (P = .009) and 10(-3) µg/mL (P = .009) of peanut. Peanut-specific IgE levels increased over the initial 4 months (P = .002) and then steadily decreased over the remaining 8 months (P = .003), whereas peanut-specific IgG4 levels increased during the 12 months (P = .014). Lastly, IL-5 levels decreased after 12 months (P = .015). No statistically significant changes were found in IL-13 levels, the percentage of regulatory T cells, or IL-10 and IFN-γ production. CONCLUSION: Peanut SLIT is able to safely induce clinical desensitization in children with peanut allergy, with evidence of immunologic changes suggesting a significant change in the allergic response. Further study is required to determine whether continued peanut SLIT is able to induce long-term immune tolerance.

Safety of a peanut oral immunotherapy protocol in children with peanut allergy.

BACKGROUND: Oral immunotherapy (OIT) offers a promising therapeutic option for peanut allergy. Given that during OIT an allergic patient ingests an allergen that could potentially cause a serious reaction, the safety of OIT is of particular concern. OBJECTIVE: The purpose of this study was to examine safety during the initial escalation day, buildup phase, and home dosing phase in subjects enrolled in a peanut OIT study. METHODS: Skin, upper respiratory tract, chest, and abdominal symptoms were recorded with initial escalation day and buildup phase dosings. Subjects also maintained daily diaries detailing symptoms after each home dosing. A statistical analysis of these data was performed. RESULTS: Twenty of 28 patients completed all phases of the study. During the initial escalation day, upper respiratory tract (79%) and abdominal (68%) symptoms were the most likely symptoms experienced. The risk of mild wheezing during the initial escalation day was 18%. The probability of having any symptoms after a buildup phase dose was 46%, with a risk of 29% for upper respiratory tract symptoms and 24% for skin symptoms. The risk of reaction with any home dose was 3.5%. Upper respiratory tract (1.2%) and skin (1.1%) symptoms were the most likely after home doses. Treatment was given with 0.7% of home doses. Two subjects received epinephrine after 1 home dose each. CONCLUSIONS: Subjects were more likely to have significant allergic symptoms during the initial escalation day when they were in a closely monitored setting than during other phases of the study. Allergic reactions with home doses were rare.