Study protocol of a phase 2, dual-centre, randomised, controlled trial evaluating the effectiveness of probiotic and egg oral immunotherapy at inducing desensitisation or sustained unresponsiveness (remission) in participants with egg allergy compared with placebo (Probiotic Egg Allergen Oral Immunotherapy for Treatment of Egg Allergy: PEAT study)

Introduction: Egg allergy is the most common food allergy in children but recent studies have shown persistence or delayed resolution into adolescence. As there is currently no effective long-term treatment, definitive treatments that improve quality of life and prevent fatalities for food allergies are required. We have previously shown that a novel treatment comprising a combination of the probiotic Lactobacillus rhamnosus CGMCC 1.3724 with peanut oral immunotherapy (OIT) is highly effective at inducing sustained unresponsiveness, with benefit persisting to 4 years after treatment cessation in the majority of initial treatment responders. In this study, we plan to extend the probiotic food OIT platform to another allergen, namely egg. We describe the protocol for a phase 2, dual-centre, randomised, controlled trial evaluating the effectiveness of probiotic and egg OIT at inducing desensitisation or sustained unresponsiveness (remission) in participants with egg allergy compared with placebo.

Methods and analysis: 80 participants aged 5-30 years of age with current egg allergy confirmed by double-blind placebo-controlled food challenge at study screening will be recruited from Australia and Singapore. There are two intervention arms-probiotic and egg OIT (active) or placebo. Interventions are administered once daily for 18 months. The primary outcome is the proportion of participants who attain 8-week sustained unresponsiveness in the active group versus placebo group.

Ethics and dissemination: This study has been approved by the Human Research Ethics Committees at the Royal Children's Hospital (HREC 2019.082) and the National Healthcare Group Domain Specific Review Board (2019/00029). Results will be published in peer-reviewed journals and disseminated via presentations at international conferences.

Trial registration number: ACTRN12619000480189.