Study protocol of a multicentre, randomised, controlled trial evaluating the effectiveness of probiotic and peanut oral immunotherapy (PPOIT) in inducing desensitisation or tolerance in children with peanut allergy compared with oral immunotherapy (OIT) alone and with placebo (the PPOIT-003 study)

Current state and advances in desensitization for peanut allergy in pediatric age

Peanut allergy affects about 1%-3% of the pediatric population in the world, with an important increase in the last decades. Nowadays, international guidelines recommend the early introduction of peanuts in the infant diet, with poor information about the quantity and the frequency of the intake. Allergen immunotherapy may represent the only therapeutic strategy able to modify the natural history of peanut allergy. In particular, oral immunotherapy showed the most promising results in terms of efficacy, but with significant rates of adverse reactions, mostly gastrointestinal. In 2020, the Food and Drug Administration and the European Medicines Agency approved Palforzia®, an oral drug for patients aged 4-17 years. Several studies are ongoing to improve the tolerability of oral immunotherapy and standardize the desensitization protocols. Sublingual immunotherapy permits to offer much lower doses than oral immunotherapy, but fewer adverse events are shown. Subcutaneous immunotherapy is associated with the greatest systemic adverse effects. Epicutaneous immunotherapy, for which Viaskin® patch was approved, has the highest safety profile. Innovative studies are evaluating the use of biological drugs, such as omalizumab or dupilumab, and probiotics, such as Lactobacillus rhamnosus, in monotherapy or associated with oral immunotherapy. Therapy for peanut allergy is constantly evolving, and new perspectives are ongoing to develop.

Probiotics in Infancy and Childhood for Food Allergy Prevention and Treatment

Food allergy represents a failure of oral tolerance mechanisms to dietary antigens. Over the past few years, food allergies have become a growing public health problem worldwide. Gut microbiota is believed to have a significant impact on oral tolerance to food antigens and in initiation and maintenance of food allergies. Therefore, probiotics have also been proposed in this field as a possible strategy for modulating both the gut microbiota and the immune system. In recent years, results from preclinical and clinical studies suggest a promising role for probiotics in food allergy prevention and treatment. However, future studies are needed to better understand the mechanisms of action of probiotics in food allergies and to design comparable study protocols using specific probiotic strains, defined doses and exposure times, and longer follow-up periods.

Association of Reaction Symptoms and Eliciting Dose With Health-Related Quality of Life in Children With Peanut Allergy

BACKGROUND

Food allergy adversely affects the health-related quality of life (HRQoL) of patients. It is unclear whether factors such as the reaction eliciting dose (ED) and the nature of allergic reaction symptoms affect HRQoL.

OBJECTIVE

To explore associations between reaction ED or the nature of allergic symptoms and HRQoL among children with peanut allergy.

METHODS

This study was a secondary analysis of baseline data from the PPOIT-003 randomized trial in 212 children aged 1 to 10 years with challenge-confirmed peanut allergy. Children's past reaction symptoms were collected by clinicians during screening. Associations between variables of interest and parent-reported child-proxy HRQoL were examined by univariable and multivariable linear regression.

RESULTS

Mean age of study participants was 5.9 years; 63.2% were male. Children with a low reaction ED of 80 mg peanut protein had significantly poorer HRQoL (β = -0.81; 95% CI, -1.61 to -0.00; P = .049) compared with children with a high ED of 2,500 mg peanut protein. Gastrointestinal symptoms (β = 0.45; 95% CI, 0.03-0.87; P = .037), lower airway symptoms (β = 0.46; 95% CI, 0.05-0.87; P = .030), multisystem involvement (β = 0.71; 95% CI, 0.25-1.16; P = .003), or anaphylaxis (β = 0.46; 95% CI, 0.04-0.87; P = .031) during a previous reaction were associated with worse HRQoL.

CONCLUSIONS

Peanut-allergic children with a lower allergen reaction threshold experienced a greater negative HRQoL impact compared with children with higher reaction thresholds. In addition, specific past allergic reaction symptoms were associated with comparatively worse HRQoL. Children experiencing these symptoms and those with lower reaction ED require increased clinical support to manage the food allergy and are likely to benefit from interventions that can improve HRQoL.

Probiotic peanut oral immunotherapy versus oral immunotherapy and placebo in children with peanut allergy in Australia (PPOIT-003): a multicentre, randomised, phase 2b trial

BACKGROUND

Oral immunotherapy is effective at inducing desensitisation to allergens and induces sustained unresponsiveness (ie, clinical remission) in a subset of patients, but causes frequent reactions. We aimed to investigate whether addition of a probiotic adjuvant improved the efficacy or safety of peanut oral immunotherapy.

METHODS

PPOIT-003, a multicentre, randomised, phase 2b trial, was conducted in three tertiary hospitals in Australia (Adelaide [SA], Melbourne [VIC], and Perth [WA]) in children aged 1-10 years, weighing more than 7 kg, with peanut allergy confirmed by a double-blind placebo-controlled food challenge (cumulative 4950 mg dose of peanut protein) and positive peanut skin prick test (≥3 mm) or peanut-specific IgE (≥0·35 kU/L). Children were randomly assigned (2:2:1) to receive probiotic and peanut oral immunotherapy (PPOIT), placebo probiotic and peanut oral immunotherapy (OIT), or placebo probiotic and placebo OIT (placebo) for 18 months, and were followed up until 12 months after completion of treatment. Oral immunotherapy consisted of increasing doses of peanut protein (commercially available food-grade 12% defatted peanut flour [50% peanut protein]) until a 2000 mg daily maintenance dose was reached. The probiotic adjuvant was a daily dose of 2 × 10¹⁰ colony-forming units of the probiotic Lactobacillus rhamnosus ATCC 53103. Placebo immunotherapy comprised maltodextrin, brown food colouring, and peanut essence, and placebo probiotic was maltodextrin. Dual primary outcomes were 8-week sustained unresponsiveness, defined as no reaction to a cumulative dose of 4950 mg peanut protein at treatment completion and 8 weeks after treatment completion, in the PPOIT versus placebo groups and the PPOIT versus OIT groups, analysed by intention to treat. Safety endpoints were adverse events during the treatment phase, and peanut ingestion and reactions in the 12-month post-treatment period. This study is registered with the Australian New Zealand Clinical Trials Registry, 12616000322437.

FINDINGS

Between July 4, 2016, and Sept 21, 2020, 201 participants were enrolled and included in the intention-to-treat analysis. 36 (46%) of 79 children in the PPOIT group and 42 (51%) of 83 children in the OIT group achieved sustained unresponsiveness compared with two (5%) of 39 children in the placebo group (risk difference 40·44% [95% CI 27·46 to 53·42] for PPOIT vs placebo, p<0·0001), with no difference between PPOIT and OIT (-5·03% [-20·40 to 10·34], p=0·52). Treatment-related adverse events were reported in 72 (91%) of 79 children in the PPOIT group, 73 (88%) of 83 children in the OIT group, and 28 (72%) of 39 children in the placebo group. Exposure-adjusted incidence of adverse events was 10·58 in the PPOIT group, 11·36 in the OIT, and 2·09 in the placebo group (ratio 0·92 [95% CI 0·85 to 0·99] for PPOIT vs OIT, p=0·042; 4·98 [4·11-6·03] for PPOIT vs placebo, p<0·0001; 5·42 [4·48-6·56] for OIT vs placebo, p<0·0001), with differences seen primarily in gastrointestinal symptoms and in children aged 1-5 years. During the 12-month post-treatment period, 60 (85%) of 71 participants in the PPOIT group, 60 (86%) of 70 participants in the OIT group, and six (18%) of 34 participants in the placebo group were eating peanut; rescue epinephrine use was infrequent (two [3%] of 71 in the PPOIT group, four [6%] of 70 in the OIT group, and none in the placebo group).

INTERPRETATION

Both PPOIT and OIT were effective at inducing sustained unresponsiveness. Addition of a probiotic did not improve efficacy of OIT, but might offer a safety benefit compared with OIT alone, particularly in preschool children.

FUNDING

National Health and Medical Research Council Australia and Prota Therapeutics.

Probiotics in food allergy

PURPOSE OF REVIEW

To perform a nonsystematic review of the literature on the possible role of probiotics for food allergy (FA).

RECENT FINDINGS

Animal model and in vitro evidence suggest that the gut microbiome could protect against FA and that probiotics could be a valid instrument. There is no consistent evidence in identifying the specific species, the dosage, and the optimal duration to obtain the correct immunomodulation. Early life supplementation with specific 'missing' immunomodulatory microbes - derived from machine learning approach to birth cohort studies - might represent a novel approach to the primary prevention of multiple human atopic diseases. However, further studies are needed.

SUMMARY

Currently, there is no positive recommendation from the main scientific societies to use probiotics neither for the treatment nor for the prevention of FA.