AR101 Oral Immunotherapy for Peanut Allergy

First Real-World Safety Analysis of Preschool Peanut Oral Immunotherapy

BACKGROUND

In 2017, a clinical trial of 37 subjects demonstrated that preschool peanut oral immunotherapy (P-OIT) was safe, with predominantly mild symptoms reported and only 1 moderate reaction requiring epinephrine.

OBJECTIVES

We sought to examine whether these findings would be applicable in a real-world setting.

METHODS

As part of a Canada-wide quality improvement project, community and academic allergists administered P-OIT to preschool-age children who had (1) skin prick test wheal diameter greater than or equal to 3 mm or specific IgE level greater than or equal to 0.35 kU/L and history of reaction and/or positive baseline oral food challenge, or (2) no ingestion history and specific IgE level greater than or equal to 5 kU/L. Over 16 to 22 weeks, patients had biweekly clinic visits for updosing, and consumed the dose daily at home between visits. Target maintenance dose was 300 mg peanut protein. Symptoms were classified using a modified World Allergy Organization Subcutaneous Immunotherapy Reaction Grading System (1 mildest, 5 fatal).

RESULTS

Of 270 patients who started P-OIT in the period 2017 to 2018, 243 reached maintenance, and 27 dropped out (10.0%); 67.8% of patients experienced reactions during buildup: 36.3% grade 1, 31.1% grade 2, and 0.40% grade 4. Eleven patients (4.10%) received epinephrine (10 patients received 1 dose, 1 patient received epinephrine on 2 separate days), representing 2.23% of reactions (12 of 538) and 0.029% of doses (12 of 41,020).

CONCLUSIONS

We are the first group to describe preschool P-OIT in a real-world multicenter setting. The treatment appears to be safe for the vast majority of patients because symptoms were generally mild and very few reactions received epinephrine; however, life-threatening reactions in a minority of patients (0.4%) can still occur.

Newly identified T cell subsets in mechanistic studies of food immunotherapy

Allergen-specific immunotherapy has shown promise for the treatment of food allergy and is currently being evaluated in clinical trials. Although immunotherapy can induce desensitization, the mechanisms underlying this process are not completely understood. Recent advances in high-throughput technologies along with concomitant advances in data analytics have enabled monitoring of cells at the single-cell level and increased the research focus on upstream cellular factors involved in the efficacy of immunotherapy, particularly the role of T cells. As our appreciation of different T cell subsets and their plasticity increases, the initial simplistic view that restoring Th1/Th2 balance by decreasing Th2 or increasing Th1 responses can ameliorate food allergy is being enhanced by a more complex model involving other T cell subsets, particularly Tregs. In this Review, we focus on the current understanding of T cell functions in food allergy, tolerance, and immunotherapy.

Walnut oral immunotherapy for desensitisation of walnut and additional tree nut allergies (Nut CRACKER): a single-centre, prospective cohort study

BACKGROUND

The safety and efficacy of oral immunotherapy for tree nut allergy has not been demonstrated to date, and its effectiveness is complicated by the high prevalence of co-allergies to several nuts. This study aimed to investigate the use of walnut oral immunotherapy in the desensitisation of walnut and additional tree nuts in patients who are co-allergic to several nuts.

METHODS

In a single-centre, prospective cohort study (the Nut Co-Reactivity ACquiring Knowledge for Elimination Recommendations study) at the Institute of Allergy, Immunology, and Paediatric Pulmonology at the Yitzhak Shamir Medical Centre, we recruited patients aged 4 years or older who were allergic to walnut, with or without co-allergy to pecan, hazelnut, and cashew. The diagnosis of each food allergy was based on a positive skin prick test or specific serum IgE (≥0·35 kU_A/L) to the corresponding nut together with a positive oral food challenge, unless an immediate (within 2 h of exposure) reaction in the past year had been documented. Patients with uncontrolled asthma or a medical contraindication to receive adrenaline were excluded. Patients were assigned to walnut oral immunotherapy or the control group (observation and strict dietary exclusion) on the basis of the order of presentation to the clinic. Oral immunotherapy began with a 4-day dose-escalation phase to establish the single highest tolerated dose, which was consumed daily at home for 24 days; subsequent monthly dose escalations were repeated until 4000 mg walnut protein was achieved. Patients who were desensitised to walnut continued to consume 1200 mg walnut protein daily for 6 months as maintenance. The primary outcome was walnut desensitisation (passing an oral food challenge with 4000 mg of walnut protein) at the end of the study, analysed by intention to treat. In patients who were co-allergic to pecan, hazelnut, and cashew, the proportion who achieved cross-desensitisation to these nuts in addition to walnut desensitisation was examined.

FINDINGS

73 patients with a walnut allergy were enrolled between May 15, 2016, and Jan 14, 2018. 49 (89%) of 55 patients in the oral immunotherapy group were desensitised to walnut compared with none of 18 patients in the control group (odds ratio 9·2, 95% CI 4·3-19·5; p<0·0001). Following walnut desensitisation, all patients who were co-allergic to pecan (n=46) were also desensitised to pecan. Additionally, 18 (60%) of 30 patients who were co-allergic to hazelnut or cashew, and 14 (93%) of 15 patients who were co-allergic to hazelnut alone, were either fully desensitised or responded to treatment. 47 (85%) of 55 patients had an adverse reaction (mostly grade 1 or 2) during up-dosing in the clinic; eight patients required intramuscular epinephrine in response to a dose at home. Of 45 patients who had follow-up data for the maintenance phase, all maintained walnut desensitisation and one patient required epinephrine during this period.

INTERPRETATION

Walnut oral immunotherapy can induce desensitisation to walnut as well as cross-desensitisation to pecan and hazelnut in patients who have tree nut co-allergies, with a reasonable safety profile. A low daily dose of the allergen maintains desensitisation.

FUNDING

None.

Microbial Adjuncts for Food Allergen Immunotherapy

PURPOSE OF REVIEW

Food allergen immunotherapy may benefit from adjunct therapies to enhance safety and efficacy. We review preclinical studies investigating the effects of probiotics and other microbial-based interventions on oral tolerance, describe the human clinical trial evidence thus far for microbial adjuncts, and discuss steps for translating research findings in this area to clinical therapy.

RECENT FINDINGS

Murine studies support that microbial-based interventions confer protection against sensitization and may augment treatment efficacy for food allergy. Microbial adjunct therapies can promote regulatory T cells and modulate Th1 vs. Th2 responses. There is a wide array of novel modalities utilizing microbial components. Ongoing efforts are focused on translating preclinical data into potential treatments. Probiotics, prebiotics, and microbial components have all been examined as microbial adjunct therapies in murine models of food allergy. The effects of probiotics appear to be strain-specific. Prebiotics and bacterial components are innovative modalities to modulate oral tolerance. Better characterization of dysbiosis in human cohorts with food allergy, deeper mechanistic understanding of microbial adjunct therapies, safety evaluation, and careful clinical trial design will be crucial for the development of microbial adjuncts for food allergen immunotherapy. Microbial adjunct therapies have the potential to enhance the efficacy, safety, and durability of food allergen immunotherapy.

Food allergen knowledge, attitude and practices among UK consumers: A structural modelling approach

Food allergies are becoming more prevalent and affect up to 1-2% of adults and 5-8% of children in the UK. This study investigated the food allergen knowledge, attitude towards food allergens and food allergy management practices among food allergic and intolerant consumers and/or their family members and carers. Questionnaires were distributed at three major Free From events in the UK in 2017 and 2018. Structural Equation Modelling (SEM) was used as a confirmatory technique to determine the model's validity. Cereals containing gluten, milk and eggs were the most common triggers reported by the consumers. Other trigger foods such as chocolate, garlic, maize, onions, red and white meat, spices, and fruits such as apples and cherries were also reported. Consumers demonstrated very good understanding on the severity of allergic reactions, prevention method and hidden egg ingredients. Overall, consumers were relatively good in the knowledge section. The participants were motivated in their personal allergen avoidance towards food allergens especially in checking food labels, preference for more free from product choices and handwashing. Consumers did not rely on dietary apps or social media to find out about allergen-free food products. Both knowledge and attitude did not translate into food allergy management practices. Significant correlation between knowledge and attitude was identified suggesting that as knowledge decreases, so will their attitude scores. This study suggests that targeted and systematic food allergy management topics and peer support could be used to improve consumers' knowledge and attitude to positively impact food allergen handling practices.

Harmonization of Terminology for Tolerated and Reactive Dose in Food Allergy Immunotherapy

Currently, there is no Food and Drug Administration-approved therapy for food allergy. Several new potential treatments are under investigation, including food allergen immunotherapy via various routes of administration, such as oral immunotherapy, epicutaneous immunotherapy, subcutaneous immunotherapy, and sublingual immunotherapy. The double-blind, placebo-controlled food challenge (DBPCFC) has traditionally been used for diagnostic purposes, but extrapolation of the specific terminology used in food allergy diagnosis to interpretation of efficacy in clinical trials is incongruent and difficult to apply. There is a need for standardization of the terminology used in food allergy clinical trials, because inconsistencies can lead to potential misinterpretation of end points. The reactive dose, previously referred to as the eliciting dose, is defined as the dose given that induces the onset of unequivocal allergic symptoms, or the dose that stops the challenge based on physician discretion. Conversely, the single highest tolerated dose is defined as the highest dose given during a food challenge that elicits either no symptoms or symptoms that do not meet stopping criteria per the study protocol. The evolving field of food allergy provides a novel opportunity to define those end points that are most meaningful for patients, which is fundamental for successful implementation, education, and safety.