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 following withdrawal of OIT. Methods We conducted a pilot clinical trial of peanut OIT at two U.S. centers. Subjects aged 1–16 were recruited and treated for up to five years with peanut OIT. The protocol was modified over time to permit dose increases to a maximum of 4000 mg peanut protein/day. Blood was collected at multiple time points. Clinical endpoints 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. 12/24 (50%) successfully passed a challenge one 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 tests as well as lower IgE levels specific for peanut, Ara h 1, and Ara h 2, and lower ratios of peanut-specific:total IgE, compared to subjects not passing. There were no differences in peanut IgG4 levels or functional activity at end-of-study. Conclusions This is the first demonstration of sustained unresponsiveness after peanut OIT, occurring in half of subjects treated up to five years. OIT favorably modified the peanut-specific immune response in all subjects completing the protocol. Smaller skin tests and lower allergen-specific IgE levels were predictive of successful outcome.

Background-There are no treatments currently available for peanut allergy. Sublingual immunotherapy is a novel approach to the treatment of peanut allergy.

Background Oral immunotherapy (OIT) is an effective experimental food allergy treatment that is limited by treatment withdrawal and the frequent reversibility of desensitization if interrupted. Newly-diagnosed preschool children may have clinical and immunological characteristics more amenable to treatment. Objective To test the safety, effectiveness, and feasibility of early OIT (E-OIT) in the treatment of peanut allergy. Methods We enrolled 40 children aged 9–36 months with suspected or known peanut allergy. Qualifying subjects reacted to peanut during an entry food challenge and were block-randomized 1:1 to receive E-OIT at goal maintenance doses of 300 or 3000 mg/day in a double-blinded fashion. The primary endpoint, sustained unresponsiveness at four weeks after stopping E-OIT (4-SU), was assessed by DBPCFC either upon achieving four pre-specified criteria, or after three maintenance years. Peanut-specific immune responses were serially analyzed. Outcomes were compared to 154 matched standard-care controls. Results Of 40 consented subjects, three (7.5%) did not qualify. Overall, 29/37 (78%) in the intent-to-treat analysis achieved 4-SU (300 mg arm, 17/20 [85%]; 3000 mg, 12/17 [71%], p=0.43) over a median of 29 months. Per-protocol, the overall proportion achieving 4-SU was 29/32 (91%). Peanut-specific IgE levels significantly declined in E-OIT-treated children, who were 19 times more likely to successfully consume dietary peanut than matched standard-care controls, in whom peanut-specific IgEs significantly increased (RR 19.42 [95%CI 8.7 – 43.7], p<0.001). Allergic side effects during E-OIT were common but all were mild-moderate. Conclusion At both doses tested, E-OIT had an acceptable safety profile and was highly successful in rapidly suppressing allergic immune responses and achieving safe dietary reintroduction.

Background Peanut-allergic subjects have highly stable pathologic antibody repertoires to the immunodominant B cell epitopes of the major peanut allergens Ara h 1-3. Objective We used a peptide microarray technique to analyze the effect of treatment with peanut oral immunotherapy (OIT) on such repertoires. Methods Measurements of total peanut-specific IgE (psIgE) and psIgG4 were made with CAP-FEIA. We analyzed sera from 22 OIT subjects and 6 controls and measured serum specific IgE and IgG4 binding to epitopes of Ara h 1-3 using a high-throughput peptide microarray technique. Antibody affinity was measured using a competitive peptide microarray as previously described. Results At baseline, psIgE and psIgG4 diversity were similar between subjects and controls, and there was broad variation in epitope recognition. After a median 41 months of OIT, polyclonal psIgG4 increased from a median 0.3 mcg/mL (IQR 0.1-0.43) at baseline to 10.5 mcg/mL (3.95-45.48) (p<0.0001) and included de novo specificities. PsIgE was reduced from a median baseline of 85.45 kUA/L (23.05-101.0) to 7.75 kUA/L (2.58-30.55) (p<0.0001). Affinity was unaffected. Although the psIgE repertoire contracted in most OIT-treated subjects, several subjects generated new IgE specificities even as the total psIgE decreased. Global epitope-specific shifts from IgE to IgG4 binding occurred, including at an informative epitope of Ara h 2. Conclusion OIT differentially alters Ara h 1-3 binding patterns. These changes are variable between subjects, not observed in controls, and include a progressive polyclonal increase in IgG4, with concurrent reduction in IgE amount and diversity.

Egg OIT is associated with tolerance acquisition in children with persistent egg allergy. Individualized dosing regimens may be necessary to achieve a full therapeutic effect in some patients.