Long-term treatment with egg oral immunotherapy enhances sustained unresponsiveness that persists after cessation of therapy

Background We previously reported the results of a randomized placebo-controlled study of egg oral immunotherapy (eOIT) in which 27.5% of subjects achieved sustained unresponsiveness (SU) after 2 years. Here we report the results of treatment through 4 years and long-term follow-up. Objective We sought to evaluate the efficacy and safety of eOIT in participants treated up to 4 years. Methods Children with egg allergy (5-18 years old) received eOIT (n = 40) for up to 4 years or placebo (n = 15) for 1 year or less. The key outcome was the percentage of subjects achieving SU by year 4. Safety and immunologic assessments were performed, and long-term follow-up questionnaires (LFQs) were administered after study conclusion (LFQ-1) and 1 year later (LFQ-2). Results Of 40 eOIT-treated subjects, 20 (50.0%) of 40 demonstrated SU by year 4. For those subjects still dosing during years 3 and 4, mild symptoms were present in 12 (54.5%) of 22 subjects. At the time of the LFQ, more subjects receiving eOIT (LFQ-1, 23/34 [68%]; LFQ-2, 21/33 [64%]) were consuming unbaked and baked egg versus placebo (LFQ-1, 2/11 [18%], P =.006; LFQ-2, 3/12 [25%], P =.04). Of subjects achieving SU, 18 (90%) of 20 completed the LFQ, with 18 (100%) of 18 reporting consumption of all forms of egg. When compared with subjects not achieving SU, subjects achieving SU had higher IgG₄ values (P =.001) and lower egg skin prick test scores (P =.0002) over time and a lower median baseline ratio of egg-specific IgE to total IgE (1.1% vs 2.7%, P =.04). Conclusions SU after eOIT is enhanced with longer duration of therapy and increases the likelihood of tolerating unbaked egg in the diet.