Sublingual immunotherapy for peanut allergy: clinical and immunologic evidence of desensitization

The future outlook on allergen immunotherapy in children: 2018 and beyond

Allergen immunotherapy (AIT) is the only currently available immune-modifying and aetiological treatment for patients suffering from IgE-mediated diseases. In childhood, it represents a suitable therapeutic option to intervene during the early phases of respiratory allergic diseases such as rhino-conjunctivitis and asthma, which is when their progression may be more easily influenced. A growing body of evidence shows that oral immunotherapy represents a promising treatment option in children with persistent IgE- mediated food allergy. The efficacy of AIT is under investigation also in patients with extrinsic atopic dermatitis, currently with controversial results. Furthermore, AIT might be a strategy to prevent the development of a new sensitization or of a (new) allergic disease. However, there are still some methodological criticisms, such as: a) the regimen of administration and the amount of the maintenance dose are both largely variable; b) the protocols of administration are not standardized; c) the description and classification of side effects is variable among studies and needs to be standardized; d) quality of life and evaluation of health economics are overall missing. All these aspects make difficult to compare each study with another. In addition, the content of major allergen(s) remains largely variable among manufacturers and the availability of AIT products differences among countries. The interest and the attention to AIT treatment are currently fervent and increasing. Well-designed studies are awaited in the near future in order to overcome the current gaps in the evidence and furtherly promote implementation strategies.

Clinical Applications of Sublingual Immunotherapy

Sublingual immunotherapy (SLIT) is effective for the treatment of allergic rhinitis and allergic asthma in adults and children. In a limited number of studies, SLIT efficacy has been demonstrated for the treatment of food allergy. SLIT has a higher safety profile versus subcutaneous immunotherapy, although some systemic reactions have been reported. Appropriate patient selection, meticulous patient education, and routine follow-up are key for the safe and effective administration of SLIT. With organization and attention to detail, adding SLIT to one's practice can provide a highly valued patient service.

Study design with staggered sampling times for evaluating sustained unresponsiveness to peanut sublingual immunotherapy

In this work, we delineate an altered study design of a pre-existing clinical trial that is currently being implemented in the Department of Pediatrics at the University of North Carolina at Chapel Hill. The purpose of the ongoing investigation of the desensitized pediatric cohort is to address the effectiveness of sublingual immunotherapy in achieving sustained unresponsiveness (SU) as assessed by repeated double-blind placebo-controlled food challenges (DBPCFC). With scarce published literature characterizing SU, the length of time off-therapy that would represent clinically meaningful benefit remains undefined. We use the new design features to assess time to loss of SU, an important efficacy endpoint, that to our knowledge, no prior study has investigated. Our work has two-fold objectives: first is to propose and discuss aspects of the altered design that would allow us to study SU and second is to explore methodology to evaluate the time to loss of SU and its association with risk factors in the context of the data originating from the trial. The salient feature of the new design is the allocation scheme of study subjects to staggered sampling timepoints when a subsequent DBPCFC is administered. Due to this feature, the time to loss of SU is either left or right censored. Additionally, some participants at study entry fail the DBPCFC, leading to what can be construed as an instantaneous failure. Through in-depth numerical studies, we examine the performance and power of a recently proposed mixture proportional hazards model specifically designed for the analysis of interval-censored data subject to instantaneous failures.

Tissue-Specific Expression of the Low-Affinity IgG Receptor, FcγRIIb, on Human Mast Cells

Immediate hypersensitivity reactions are induced by the interaction of allergens with specific IgE antibodies bound via FcεRI to mast cells and basophils. While these specific IgE antibodies are needed to trigger such reactions, not all individuals harboring IgE exhibit symptoms of allergy. The lack of responsiveness seen in some subjects correlates with the presence of IgG antibodies of the same specificity. In cell culture studies and in vivo animal models of food allergy and anaphylaxis such IgG antibodies have been shown to exert suppression via FcγRIIb. However, the reported absence of this inhibitory receptor on primary mast cells derived from human skin has raised questions about the role of IgG-mediated inhibition of immediate hypersensitivity in human subjects. Here, we tested the hypothesis that mast cell FcγRIIb expression might be tissue specific. Utilizing a combination of flow cytometry, quantitative PCR, and immunofluorescence staining of mast cells derived from the tissues of humanized mice, human skin, or in fixed paraffin-embedded sections of human tissues, we confirm that FcγRIIb is absent from dermal mast cells but is expressed by mast cells throughout the gastrointestinal tract. IgE-induced systemic anaphylaxis in humanized mice is strongly inhibited by antigen-specific IgG. These findings support the concept that IgG, signaling via FcγRIIb, plays a physiological role in suppressing hypersensitivity reactions.

Comparison of sublingual immunotherapy and oral immunotherapy in peanut allergy

The prevalence of food allergy has been increasing over the past few decades at an alarming rate with peanut allergy affecting about 2% of children. Both oral immunotherapy (OIT) and sublingual immunotherapy (SLIT) have shown promise as a treatment option for peanut allergy. Immunotherapy induces desensitization and reduces the risk of reaction during accidental ingestion and may also enable those who are successfully desensitized to include the food allergen in their diet. OIT has been very well studied and has been found to be more efficacious that SLIT with an acceptable safety profile. However, SLIT is associated with fewer side effects. Studies indicate that a combination of SLIT and OIT may together induce a significant increase in challenge thresholds with fewer adverse events. More head-to-head clinical trials that direct compare OIT and SLIT as well as SLIT and OIT combination studies are warranted.

Tree nut allergies: Allergen homology, cross-reactivity, and implications for therapy

Tree nut allergy is a potentially life-threatening disease that is increasing in prevalence, now affecting 1% of the general population in the United States. While other food allergies often resolve spontaneously, tree nut allergies are outgrown in less than 10% of cases. Due to the likelihood of cross-sensitization to multiple tree nut allergens, the current treatment guideline is strict avoidance of all nuts once one tree nut allergy has been diagnosed. For example, walnut and pecan are highly cross-reactive, along with cashew and pistachio, but the extent of clinical, IgE-mediated cross-reactivity among other tree nuts remains unclear, therefore making avoidance of all tree nuts a safe approach. There have been recent advances in immunotherapy for food allergies. For instance, there are investigational immunotherapies for milk, egg and peanut allergies, specifically oral immunotherapy, sublingual immunotherapy and epicutaneous immunotherapy. However, there are no large randomized controlled clinical trials for tree nut allergies. Even though there has been less research into tree nut allergy immunotherapies, the evidence of T-cell cross-reactivity among tree nuts exists in animal models and in T cells from allergic patients indicates that immunotherapeutic interventions may be possible. Here, we review the literature regarding epidemiology, allergen homology and cross-reactivity among tree nuts, and explore how current findings can be employed for effective therapy.

Safety and efficacy of epicutaneous immunotherapy for food allergy

Food allergy is increasingly common in children, affecting about 4%-8%. The mainstays of management remain allergen avoidance and emergency preparedness to treat allergic reactions with emergency medications. Unfortunately, these approaches are unsatisfactory for many patients and their families as the restrictions, constant vigilance, and unpredictable severity of allergic reactions negatively impact quality of life. In recent decades, there has been significant interest in developing treatments for food allergy that lead to desensitization to increase thresholds for triggering allergic reactions and decrease the risk of reacting to allergen-contaminated food products. Epicutaneous immunotherapy (EPIT) is a novel therapy that is currently under investigation, delivering allergen via repeated applications to the skin and targeting antigen-presenting cells in the superficial skin layers. Murine models have demonstrated that allergen uptake is an active process by skin dendritic cells with subsequent migration to draining lymph nodes. Allergen exposure to the non-vascularized epidermis limits systemic absorption, contributing to the high-safety profile. Results from murine experiments showed that EPIT has comparable efficacy as subcutaneous immunotherapy in terms of challenge outcomes, airway hyper-responsiveness, and immunologic parameters. Several clinical trials of EPIT have recently been completed or are ongoing. Results support the high safety and tolerability of this approach. Efficacy data suggest that the change in threshold eliciting dose following 1 year of therapy is less than that seen compared to high-dose (2-4 g peanut protein) oral immunotherapy, but more prolonged treatment with EPIT appears to lead to increasing desensitization. Additional data from larger-scale studies should provide a more robust assessment of safety and efficacy of EPIT.

BSACI guideline for the diagnosis and management of peanut and tree nut allergy

Peanut nut and tree nut allergy are characterised by IgE mediated reactions to nut proteins. Nut allergy is a global disease. Limited epidemiological data suggest varying prevalence in different geographical areas. Primary nut allergy affects over 2% of children and 0.5% of adults in the UK. Infants with severe eczema and/or egg allergy have a higher risk of peanut allergy. Primary nut allergy presents most commonly in the first five years of life, often after the first known ingestion with typical rapid onset IgE-mediated symptoms. The clinical diagnosis of primary nut allergy can be made by the combination of a typical clinical presentation and evidence of nut specifc IgE shown by a positive skin prick test (SPT) or specific IgE (sIgE) test. Pollen food syndrome is a distinct disorder, usually mild, with oral/pharyngeal symptoms, in the context of hay fever or pollen sensitisation, which can be triggered by nuts. It can usually be distinguish clinically from primary nut allergy. The magnitude of a SPT or sIgE relates to the probability of clinical allergy, but does not relate to clinical severity. SPT of ≥ 8 mm or sIgE ≥ 15 KU/L to peanut is highly predictive of clinical allergy. Cut off values are not available for tree nuts. Test results must be interpreted in the context of the clinical history. Diagnostic food challenges are usually not necessary but may be used to confirm or refute a conflicting history and test result. As nut allergy is likely to be a long-lived disease, nut avoidance advice is the cornerstone of management. Patients should be provided with a comprehensive management plan including avoidance advice, patient specific emergency medication and an emergency treatment plan and training in administration of emergency medication. Regular re-training is required.

Food Allergy

PURPOSE OF REVIEW

The goal of this review is to present an updated summary of the natural history of major childhood and adult food allergies and report recent advances in potential treatments for food allergy.

RECENT FINDINGS

The most common childhood food allergies are typically outgrown by adolescence or adulthood. However, peanut/tree nut allergies appear to more commonly persist into adulthood. Adults can develop new IgE-mediated food allergies; the most common is oral allergy syndrome. There are multiple different approaches being tried as possible treatments for food allergy. The prevalence of food allergy appears to be increasing but the varied approaches to treatment are being actively pursued such that an approved modality may not be too far in the future.

Food Allergy

PURPOSE OF REVIEW

The goal of this review is to present an updated summary of the natural history of major childhood and adult food allergies and report recent advances in potential treatments for food allergy.

RECENT FINDINGS

The most common childhood food allergies are typically outgrown by adolescence or adulthood. However, peanut/tree nut allergies appear to more commonly persist into adulthood. Adults can develop new IgE-mediated food allergies; the most common is oral allergy syndrome. There are multiple different approaches being tried as possible treatments for food allergy. The prevalence of food allergy appears to be increasing but the varied approaches to treatment are being actively pursued such that an approved modality may not be too far in the future.

The Nuts and Bolts of Food Immunotherapy: The Future of Food Allergy

Food allergies are on the rise and have a major impact on the quality of life of the food allergic child and their family. Currently, the mainstream treatment for food allergies is strict avoidance and elimination of the allergenic food(s) from the patient's diet in order to prevent an allergic reaction. However, recent advances in research have presented new therapeutic options for food allergic patients that are potentially becoming promising alternatives to traditional treatment. Food immunotherapy is the most popular of these new emerging interventions and has been studied intensively over the last decade for various foods. In this review, we discuss this exciting new development that is aspiring to become part of the mainstream therapy for food allergy.

EAACI Guidelines on allergen immunotherapy: IgE-mediated food allergy

Food allergy can result in considerable morbidity, impairment of quality of life, and healthcare expenditure. There is therefore interest in novel strategies for its treatment, particularly food allergen immunotherapy (FA-AIT) through the oral (OIT), sublingual (SLIT), or epicutaneous (EPIT) routes. This Guideline, prepared by the European Academy of Allergy and Clinical Immunology (EAACI) Task Force on Allergen Immunotherapy for IgE-mediated Food Allergy, aims to provide evidence-based recommendations for active treatment of IgE-mediated food allergy with FA-AIT. Immunotherapy relies on the delivery of gradually increasing doses of specific allergen to increase the threshold of reaction while on therapy (also known as desensitization) and ultimately to achieve post-discontinuation effectiveness (also known as tolerance or sustained unresponsiveness). Oral FA-AIT has most frequently been assessed: here, the allergen is either immediately swallowed (OIT) or held under the tongue for a period of time (SLIT). Overall, trials have found substantial benefit for patients undergoing either OIT or SLIT with respect to efficacy during treatment, particularly for cow's milk, hen's egg, and peanut allergies. A benefit post-discontinuation is also suggested, but not confirmed. Adverse events during FA-AIT have been frequently reported, but few subjects discontinue FA-AIT as a result of these. Taking into account the current evidence, FA-AIT should only be performed in research centers or in clinical centers with an extensive experience in FA-AIT. Patients and their families should be provided with information about the use of FA-AIT for IgE-mediated food allergy to allow them to make an informed decision about the therapy.

Current Status of Potential Therapies for IgE-Mediated Food Allergy

PURPOSE OF REVIEW

The goal of this review is to provide the reader with an updated summary of published trial data regarding the use of oral immunotherapy (OIT), sublingual immunotherapy (SLIT), and epicutaneous immunotherapy (EPIT) for treatment of IgE-mediated food allergies.

RECENT FINDINGS

Data from phase 2 trials for treatment of peanut allergy with OIT and EPIT reveal an increase in the threshold of reactivity for peanut-allergic children. Compared to EPIT, OIT promotes a greater increase in the threshold of reactivity; however, adverse events are more common with OIT. OIT, EPIT, and SLIT appear to modulate the immune response for some food-allergic individuals. Data regarding utility for treatment of food allergies regardless of modality is limited to few foods, as is investigation into treatment of food-allergic infants, young children, and adults. Future trials are likely to focus on young children, food allergies other than peanut, and treatment of multifood-allergic individuals.

Allergen-Specific Immunotherapies for Food Allergy

With rising prevalence of food allergy (FA), allergen-specific immunotherapy (AIT) for FA has become an active area of research in recent years. In AIT, incrementally increasing doses of inciting allergen are given with the goal to increase tolerance, initially through desensitization, which relies on regular exposure to allergen. With prolonged therapy in some subjects, AIT may induce sustained unresponsiveness, in which tolerance is retained after a period of allergen avoidance. Methods of AIT currently under study in humans include oral, sublingual, epicutaneous, and subcutaneous delivery of modified allergenic protein, as well as via DNA-based vaccines encoding allergen with lysosomal-associated membrane protein I. The balance of safety and efficacy varies by type of AIT, as well as by targeted allergen. Age, degree of sensitization, and other comorbidities may affect this balance within an individual patient. More recently, AIT with modified proteins or combined with immunomodulatory therapies has shown promise in making AIT safer and/or more effective. Though methods of AIT are neither currently advised by experts (oral immunotherapy [OIT]) nor widely available, AIT is likely to become a part of recommended management of FA in the coming years. Here, we review and compare methods of AIT currently under study in humans to prepare the practitioner for an exciting new phase in the care of food allergic patients in which improved tolerance to inciting foods will be a real possibility.

The clinical and immunological effects of Pru p 3 sublingual immunotherapy on peach and peanut allergy in patients with systemic reactions

BACKGROUND

The peach non-specific lipid transfer protein, Pru p 3, is the primary sensitizer in fruits and responsible for severe reactions in the Mediterranean area. Peach allergy is frequently associated with other allergies such as peanut. Therefore, it is important to assess how specific immunotherapy to Pru p 3 could affect both peach and peanut tolerance.

OBJECTIVES

To evaluate peach and peanut desensitization and immunological changes after 1 year of Pru p 3 sublingual immunotherapy (SLIT) in patients with systemic allergic reactions to peach and/or peanut.

METHODS

Forty-eight peach allergic patients, 36 treated with SLIT and 12 non-treated, were monitored for 12 months. Treated patients were subclassified as peanut allergic (Group A), sensitized (Group B) or tolerant (Group C). SLIT effect was evaluated by skin prick test (SPT) reactivity and food challenge. Immunological changes were evaluated by monitoring sIgE and sIgG4 levels and basophil reactivity.

RESULTS

After 1 year of SLIT, the weal area in SPT significantly decreased and a significant increase in peach threshold in treated patients was observed (P < 0.001). Patients in Group A showed a significant decrease in peanut SPT weal area and an increase in peanut threshold (P < 0.001). Immunological changes were observed in treated patients only, with a significant decrease in sIgE and a parallel increase in sIgG4, sIgG4/sIgE and basophil reactivity for both Pru p 3 and Ara h 9.

CONCLUSIONS AND CLINICAL RELEVANCE

After 1 year, Pru p 3 SLIT induces both desensitization and immunological changes not only for peach but also for other food allergens relevant in the induction of severe reactions such as peanut.

The current state of food allergy therapeutics

The prevalence of IgE mediated food allergy is an increasing public health concern. The current standard of treatment is strict avoidance of the offending food(s). There are no FDA approved treatments for food allergy. This review will provide an overview of strategies currently under investigation for the treatment of food allergy. The main focus of research has been directed at various forms of immunotherapy, including oral, sublingual and epicutaneous delivery routes. While oral immunotherapy (OIT) has shown the greatest promise for efficacy in terms of amount of protein that can be ingested, it has also demonstrated less tolerability and a less favorable safety profile as compared to sublingual immunotherapy (SLIT) and epicutaneous immunotherapy (EPIT), which offers the least protection but has the best safety and tolerability profile. Investigation is also underway for modified antigens that may be used for immunotherapy and for adjuncts that may help facilitate immunotherapy, including biologics such as anti-IgE therapy, and also probiotics. There are also a number of preclinical concepts that are being evaluated to manipulate the antigens and/or the immune system that may one day be translatable to patients.

Dermatophagoides pteronyssinus immunotherapy changes the T-regulatory cell activity

Subcutaneous specific immunotherapy (SCIT) has been shown to modify the Dermatophagoides pteronissinus (DP) allergic response, characterized by generation of Treg cells. However, studies have reported no changes in the proportion of Treg cells after immunotherapy, indicating that the effects may be due to modifications in their regulatory activities. We aimed to determine whether Tregs generated by DP-SCIT can switch the allergic response to tolerant and study the involvement of suppressive cytokines on it. Twenty-four DP-allergic rhinitis patients were recruited, 16 treated with DP-SCIT and 8 untreated. Treg and T effector cells were isolated before and after DP-SCIT, and cocultured in different combinations with α-IL-10, α-TGF-β blocking antibodies and nDer p 1. Treg cells after DP-SCIT increased Th1 and decreased Th2 and Th9 proliferation. Similarly, they increased IL-10 and decreased IL-4 and IL-9-producing cells. α-IL-10 affected the activity of Treg cells obtained after DP-SCIT only. Finally, DP-specific IgG4 levels, Treg percentage and IL-10 production were correlated after DP-SCIT. These results demonstrate that DP-SCIT induces Treg cells with different suppressive activities. These changes could be mediated by IL-10 production and appear to play an important role in the induction of the tolerance response leading to a clinical improvement of symptoms.

Oral immunotherapy for food allergy: A Spanish guideline. Egg and milk immunotherapy Spanish guide (ITEMS GUIDE). Part 2: Maintenance phase of cow milk (CM) and egg oral immunotherapy (OIT), special treatment dosing schedules. Models of dosing schedules of OIT with CM and EGG

INTRODUCTION

Cow's milk and egg are the most frequent causes of food allergy in the first years of life. Treatments such as oral immunotherapy (OIT) have been investigated as an alternative to avoidance diets. No clinical practice guides on the management of OIT with milk and egg are currently available.

OBJECTIVES

To develop a clinical guide on OIT based on the available scientific evidence and the opinions of experts.

METHODS

A review was made of studies published in the period between 1984 and June 2016, Doctoral Theses published in Spain, and summaries of communications at congresses (SEAIC, SEICAP, EAACI, AAAAI), with evaluation of the opinion consensus established by a group of experts pertaining to the scientific societies SEICAP and SEAIC.

RESULTS

Recommendations have been established regarding the indications, requirements and practical aspects of the different phases of OIT, as well as special protocols for patients at high risk of suffering adverse reactions.

CONCLUSIONS

A clinical practice guide is presented for the management of OIT with milk and egg, based on the opinion consensus of Spanish experts.

Physicians' experience and opinion on contraindications to allergen immunotherapy: The CONSIT survey

BACKGROUND

Allergen immunotherapy (AIT) is the only disease-modifying treatment in allergy but several contraindications limit its use.

OBJECTIVE

To collect the outcome of using AIT in theoretically contraindicated situations in real patients in the Contraindications to Specific ImmunoTherapy (CONSIT) survey.

METHODS

The CONSIT is an electronic European Academy of Allergy and Clinical Immunology survey conducted to gather the safety outcomes of patients undergoing subcutaneous, sublingual, or venom AIT and the opinions of physicians on each of 17 selected conditions: children younger than 5 years; starting AIT during pregnancy; controlled severe asthma; arrhythmias; coronary disease; cancer; autoimmune disease; bone marrow and solid organ transplantation; human immunodeficiency virus and acquired immunodeficiency syndrome; previous anaphylaxis during AIT; use of β-blockers, angiotensin-converting inhibitors, cyclosporine, and methotrexate; and inability to communicate. Safety using AIT was reported in a 3-point scale: 1, "no problems"; 2, "minor problems" (requiring only dose modifications); and 3, "major problems" (AIT not tolerated). Each physician was asked about the degree of contraindication that each condition should have: no contraindication (score 1), relative contraindication (score 2), or absolute contraindication (score 3).

RESULTS

Five hundred twenty physicians (75% Europeans, 89% allergists) reported on approximately 45,000 patients undergoing AIT with any of these conditions. Major problems were infrequent, occurring more frequently in patients with asthma (9.9%) and with previous anaphylaxis from AIT (9.5%). Regarding opinions, experienced physicians scored a significantly lower mean for all conditions than non-experienced physicians for all routes.

CONCLUSION

Major problems were infrequent and experienced physicians were less likely to be restrictive in the use of AIT.

Clinical aspects of oral immunotherapy for the treatment of allergies

Studies on oral immunotherapy (OIT) have been increasing worldwide. Nevertheless, some concerns exist with this treatment. The rate of long-term sustained unresponsiveness is quite low; moreover, the desensitization or sustained unresponsiveness does not equate to tolerance. Furthermore, adverse reactions are frequent. Therefore, safe and feasible methods for long-term therapies are needed. Novel therapies such as low-dose OIT, hypoallergenic products, and OIT in combination with omalizumab are reported as effective for inducing sustained unresponsiveness and may lead to fewer adverse reactions than standard OIT. Increased safety will contribute to feasibility of OIT. Currently, oral food challenge (OFC) with the low target dose has been reported. We may reduce the need for OIT by implementing low-dose OFC. More effective, safe, and feasible OIT strategies are needed.

Allergen immunotherapy for IgE-mediated food allergy: a systematic review and meta-analysis

BACKGROUND

The European Academy of Allergy and Clinical Immunology (EAACI) is developing Guidelines for Allergen Immunotherapy (AIT) for IgE-mediated Food Allergy. To inform the development of clinical recommendations, we sought to critically assess evidence on the effectiveness, safety and cost-effectiveness of AIT in the management of food allergy.

METHODS

We undertook a systematic review and meta-analysis that involved searching nine international electronic databases for randomized controlled trials (RCTs) and nonrandomized studies (NRS). Eligible studies were independently assessed by two reviewers against predefined eligibility criteria. The quality of studies was assessed using the Cochrane Risk of Bias tool for RCTs and the Cochrane ACROBAT-NRS tool for quasi-RCTs. Random-effects meta-analyses were undertaken, with planned subgroup and sensitivity analyses.

RESULTS

We identified 1814 potentially relevant papers from which we selected 31 eligible studies, comprising of 25 RCTs and six NRS, studying a total of 1259 patients. Twenty-five trials evaluated oral immunotherapy (OIT), five studies investigated sublingual immunotherapy, and one study evaluated epicutaneous immunotherapy. The majority of these studies were in children. Twenty-seven studies assessed desensitization, and eight studies investigated sustained unresponsiveness postdiscontinuation of AIT. Meta-analyses demonstrated a substantial benefit in terms of desensitization (risk ratio (RR) = 0.16, 95% CI 0.10, 0.26) and suggested, but did not confirm sustained unresponsiveness (RR = 0.29, 95% CI 0.08, 1.13). Only one study reported on disease-specific quality of life (QoL), which reported no comparative results between OIT and control group. Meta-analyses revealed that the risk of experiencing a systemic adverse reaction was higher in those receiving AIT, with a more marked increase in the risk of local adverse reactions. Sensitivity analysis excluding those studies judged to be at high risk of bias demonstrated the robustness of summary estimates of effectiveness and safety of AIT for food allergy. None of the studies reported data on health economic analyses.

CONCLUSIONS

AIT may be effective in raising the threshold of reactivity to a range of foods in children with IgE-mediated food allergy whilst receiving (i.e. desensitization) and post-discontinuation of AIT. It is, however, associated with a modest increased risk in serious systemic adverse reactions and a substantial increase in minor local adverse reactions. More data are needed in relation to adults, long term effects, the impact on QoL and the cost-effectiveness of AIT.

Differences and similarities between sublingual immunotherapy of allergy and oral tolerance

Allergen immunotherapy is the only treatment altering the natural course of IgE-mediated allergies. Whereas the subcutaneous route for immunotherapy (SCIT) has been historically considered as a reference, we discuss herein the relative advantages of the sublingual and oral routes as alternatives to SCIT in order to elicit allergen-specific tolerance. The buccal and gut immune systems are similarly organized to favor immune tolerance to antigens/allergens, due to the presence of tolerogenic dendritic cells and macrophages promoting the differentiation of CD4⁺ regulatory T cells. Sublingual immunotherapy (SLIT) is now established as a valid treatment option, with clinical efficacy demonstrated in allergic rhinoconjunctivitis (to either grass, tree, weed pollens or mite allergens) and encouraging results obtained in the management of mild/moderate allergic asthma. While still exploratory, oral immunotherapy (OIT) has shown promising results in the desensitization of patients with food allergies. We review at both biological and clinical levels the perspectives currently pursued for those two mucosal routes.

Quantitative Assessment of the Safety Benefits Associated with Increasing Clinical Peanut Thresholds Through Immunotherapy

BACKGROUND

Peanut immunotherapy studies are conducted with the aim to decrease the sensitivity of patients to peanut exposure with the outcome evaluated by testing the threshold for allergic response in a double-blind placebo-controlled food challenge. The clinical relevance of increasing this threshold is not well characterized.

OBJECTIVE

We aimed to quantify the clinical benefit of an increased threshold for peanut-allergic patients.

METHODS

Quantitative risk assessment was performed by matching modeled exposure to peanut protein with individual threshold levels. Exposure was modeled by pairing US consumption data for various food product categories with potential contamination levels of peanut that have been demonstrated to be present on occasion in such food products. Cookies, ice cream, doughnuts/snack cakes, and snack chip mixes were considered in the risk assessment.

RESULTS

Increasing the baseline threshold before immunotherapy from 100 mg or less peanut protein to 300 mg peanut protein postimmunotherapy reduces the risk of experiencing an allergic reaction by more than 95% for all 4 food product categories that may contain trace levels of peanut residue. Further increase in the threshold to 1000 mg of peanut protein had an additional quantitative benefit in risk reduction for all patients reacting to 300 mg or less at baseline.

CONCLUSIONS

We conclude that achieving thresholds of 300 mg and 1000 mg of peanut protein by peanut immunotherapy is clinically relevant, and that the risk for peanut-allergic patients who have achieved this increased threshold to experience an allergic reaction is reduced in a clinically meaningful way.

Expanding Diversity and Common Goal of Regulatory T and B Cells. II: In Allergy, Malignancy, and Transplantation

Regulation of immune response was found to play an important role in the course of many diseases such as autoimmune diseases, allergy, malignancy, organ transplantation. The studies on immune regulation focus on the role of regulatory cells (Tregs, Bregs, regulatory myeloid cells) in these disorders. The number and function of Tregs may serve as a marker of disease activity. As in allergy, the depletion of Tregs is observed and the results of allergen-specific immunotherapy could be measured by an increase in the population of IL-10⁺ regulatory cells. On the basis of the knowledge of anti-cancer immune response regulation, new directions in therapy of tumors are introduced. As the proportion of regulatory cells is increased in the course of neoplasm, the therapeutic action is directed at their inhibition. The depletion of Tregs may be also achieved by an anti-check-point blockade, anti-CD25 agents, and inhibition of regulatory cell recruitment to the tumor site by affecting chemokine pathways. However, the possible favorable role of Tregs in cancer development is considered and the plasticity of immune regulation should be taken into account. The new promising direction of the treatment based on regulatory cells is the prevention of transplant rejection. A different way of production and implementation of classic Tregs as well as other cell types such as double-negative cells, Bregs, CD4⁺ Tr1 cells are tested in ongoing trials. On the basis of the results of current studies, we could show in this review the significance of therapies based on regulatory cells in different disorders.

Mechanistic correlates of clinical responses to omalizumab in the setting of oral immunotherapy for milk allergy

BACKGROUND

In our recent clinical trial, the addition of omalizumab to oral immunotherapy (OIT) for milk allergy improved safety, but no significant clinical benefit was detected.

OBJECTIVE

We sought to investigate mechanisms by which omalizumab modulates immunity in the context of OIT and to identify baseline biomarkers that predict subgroups of patients most likely to benefit from omalizumab.

METHODS

Blood was obtained at baseline and multiple time points during a placebo-controlled trial of OIT for milk allergy in which subjects were randomized to receive omalizumab or placebo. Immunologic outcomes included measurement of basophil CD63 expression and histamine release and casein-specific CD4⁺ regulatory T-cell proliferation. Biomarkers were analyzed in relationship to measurements of safety and efficacy.

RESULTS

Milk-induced basophil CD63 expression was transiently reduced in whole blood samples from both omalizumab- and placebo-treated subjects. However, IgE-dependent histamine release increased in washed cell preparations from omalizumab- but not placebo-treated subjects. No increase in regulatory T-cell frequency was evident in either group. Subjects with lower rates of adverse reactions, regardless of arm, experienced better clinical outcomes. Pre-OIT basophil reactivity positively associated with occurrence of symptoms during OIT, whereas the baseline milk IgE/total IgE ratio correlated with the likelihood of achieving sustained unresponsiveness. A combination of baseline basophil and serologic biomarkers defined a subset of patients in which adjunctive therapy with omalizumab was associated with attainment of sustained unresponsiveness and a reduction in adverse reactions.

CONCLUSIONS

Combining omalizumab therapy with milk OIT led to distinct alterations in basophil reactivity but not T-cell responses. Baseline biomarkers can identify subjects most likely to benefit from adjunctive therapy with omalizumab.

Clinical practice recommendations for allergen-specific immunotherapy in children: the Italian consensus report

Allergen-specific immunotherapy (AIT) is currently recognized as a clinically effective treatment for allergic diseases, with a unique disease-modifying effect. AIT was introduced in clinical practice one century ago, and performed in the early years with allergenic extracts of poor quality and definition. After the mechanism of allergic reaction were recognized, the practice of AIT was refined, leading to remarkable improvement in the efficacy and safety profile of the treatment. Currently AIT is accepted and routinely prescribed worldwide for respiratory allergies and hymenoptera venom allergy. Both the subcutaneous (SCIT) and sublingual (SLIT) routes of administration are used in the pediatric population.AIT is recommended in allergic rhinitis/conjunctivitis with/without allergic asthma, with an evidence of specific IgE-sensitization towards clinically relevant inhalant allergens. Long-term studies provided evidence that AIT can also prevent the onset of asthma and of new sensitizations. The favorable response to AIT is strictly linked to adherence to treatment, that lasts 3-5 years. Therefore, several factors should be carefully evaluated before starting this intervention, including the severity of symptoms, pharmacotherapy requirements and children and caregivers' preference and compliance.In recent years, there have been increasing interest in the role of AIT for the treatment of IgE-associated food allergy and extrinsic atopic dermatitis. A growing body of evidence shows that oral immunotherapy represents a promising treatment option for IgE-associated food allergy. On the contrary, there are still controversies on the effectiveness of AIT for patients with atopic dermatitis.This consensus document was promoted by the Italian Society of Pediatric Allergy and Immunology (SIAIP) to provide evidence-based recommendations on AIT in order to implement and optimize current prescription practices of this treatment for allergic children.

Food-specific sublingual immunotherapy is well tolerated and safe in healthy dogs: a blind, randomized, placebo-controlled study

BACKGROUND

Food allergies are increasing in prevalence but no treatment strategies are currently available to cure dogs with food allergy. Over the past decade, experimental food allergen-specific sublingual immunotherapy (FA-SLIT) has emerged as a potential treatment for food allergies in human medicine. However, FA-SLIT has not been investigated in dogs. Therefore, the objective of this study was to prospectively evaluate the safety, tolerability and dispenser sterility of FA-SLIT in healthy dogs before testing it in food allergic dogs. Eight experimental healthy beagle dogs, never orally exposed to peanut, were randomized in two groups to receive SLIT with peanut or placebo for 4 months. Subjects were monitored daily for local and systemic adverse effects. Blood samples for complete blood count and serum biochemistry, and urine for urinalysis were collected and the dogs' body weight was recorded at day 0, 35 and 119 of the SLIT treatment. Sera for the determination of peanut-specific IgG and IgE were collected at day 0, 35, 49, 70, 91, 105 and 119. Intradermal tests were performed before (day 0) and after (day 119) the experiment. The content of each dispenser used to administer treatment or placebo was tested for sterility after usage. In order to assess the presence or absence of sensitization, dogs were challenged 6 months after the end of the study with 2000 μg of peanut extract daily for 7 to 14 days.

RESULTS

All dogs completed the study. The treatment did not provoke either local or systemic side-effects. Peanut-specific IgG significantly increased in treatment group. Even though a significant increase in peanut-specific IgE was also seen, intradermal tests were negative in all dogs before and after the experiment, and the challenge test did not trigger any adverse reactions in the treated dogs, which shows the protocol did not cause sensitization to peanut, but nevertheless primed the immune system as indicated by the humoral immune response. All dispenser solutions were sterile.

CONCLUSIONS

Our results demonstrate that the used peanut-SLIT protocol is well tolerated and safe in healthy dogs. Further studies should evaluate tolerability, safety and efficacy in dogs with food allergy.

Role of Regulatory Cells in Oral Tolerance

The immune system is continuously exposed to great amounts of different antigens from both food and intestinal microbes. Immune tolerance to these antigens is very important for intestinal and systemic immune homeostasis. Oral tolerance is a specific type of peripheral tolerance induced by exposure to antigen via the oral route. Investigations on the role of intestinal immune system in preventing hypersensitivity reactions to innocuous dietary and microbial antigens have been intensively performed during the last 2 decades. In this review article, we discuss how food allergens are recognized by the intestinal immune system and draw attention to the role of regulatory T (Treg) and B (Breg) cells in the establishment of oral tolerance and tolerogenic features of intestinal dendritic cells. We also emphasize the potential role of tonsils in oral tolerance induction because of their anatomical location, cellular composition, and possible usage to develop novel ways of specific immunotherapy for the treatment of allergic diseases.

Update on Potential Therapies for IgE-Mediated Food Allergy

PURPOSE OF REVIEW

Food allergy is common, affecting up to 8% of children in the USA. Currently, therapy is limited to avoidance of the implicated allergen and availability of self-injectable epinephrine. However, several new approaches to food allergy are under investigation. This article reviews the published data on these new approaches.

RECENT FINDINGS

Oral immunotherapy, in which allergic subjects are exposed to increasing amounts of antigen, can be accomplished in the majority of allergic individuals. However, this approach is not a cure as most patients will react after cessation of regular intake. In addition, there is a high rate of side effects. Other approaches include epicutaneous immunotherapy, therapy with anti-IgE medications, and use of Chinese herbs. Several novel approaches on food allergy are under study. At the current time, these approaches show promise for preventing severe reactions to accidental exposures. However, there is little evidence that current approaches will represent a true cure for food allergy.

New pharmaceutical approaches for the treatment of food allergies

INTRODUCTION

Allergic diseases constitute one of the most common causes of chronic illness in developed countries. The main mechanism determining allergy is an imbalance between Th1 and Th2 response towards Th2.

AREAS COVERED

This review describes the mechanisms underlying the natural tolerance to food components and the development of an allergic response in sensitized individuals. Furthermore, therapeutic approaches proposed to manage these abnormal immunologic responses food are also presented and discussed.

EXPERT OPINION

In the past, management of food allergies has consisted of the education of patients to avoid the ingestion of the culprit food and to initiate the therapy (e.g. self-injectable epinephrine) in case of accidental ingestion. In recent years, sublingual/oral immunotherapies based on the continuous administration of small amounts of the allergen have been developed. However, the long periods of time needed to obtain significant desensitization and the generation of adverse effects, limit their use. In order to solve these drawbacks, strategies to induce tolerance are being studied, such as the use of either adjuvant immunotherapy in order to facilitate the reversion of the Th2 response towards Th1 or the use of monoclonal antibodies to block the main immunogenic elements.

Epicutaneous immunotherapy for the treatment of peanut allergy in children and young adults

BACKGROUND

Peanut allergy is common, life-threatening, and without therapeutic options. We evaluated peanut epicutaneous immunotherapy (EPIT) by using Viaskin Peanut for peanut allergy treatment.

OBJECTIVE

We sought to evaluate the clinical, safety, and immunologic effects of EPIT for the treatment of peanut allergy.

METHODS

In this multicenter, double-blind, randomized, placebo-controlled study, 74 participants with peanut allergy (ages 4-25 years) were treated with placebo (n = 25), Viaskin Peanut 100 μg (VP100; n = 24) or Viaskin Peanut 250 μg (VP250; n = 25; DBV Technologies, Montrouge, France). The primary outcome was treatment success after 52 weeks, which was defined as passing a 5044-mg protein oral food challenge or achieving a 10-fold or greater increase in successfully consumed dose from baseline to week 52. Adverse reactions and mechanistic changes were assessed.

RESULTS

At week 52, treatment success was achieved in 3 (12%) placebo-treated participants, 11 (46%) VP100 participants, and 12 (48%) VP250 participants (P = .005 and P = .003, respectively, compared with placebo; VP100 vs VP250, P = .48). Median change in successfully consumed doses were 0, 43, and 130 mg of protein in the placebo, VP100, and VP250 groups, respectively (placebo vs VP100, P = .014; placebo vs VP250, P = .003). Treatment success was higher among younger children (P = .03; age, 4-11 vs >11 years). Overall, 14.4% of placebo doses and 79.8% of VP100 and VP250 doses resulted in reactions, predominantly local patch-site and mild reactions (P = .003). Increases in peanut-specific IgG₄ levels and IgG₄/IgE ratios were observed in peanut EPIT-treated participants, along with trends toward reduced basophil activation and peanut-specific T_H2 cytokines.

CONCLUSIONS

Peanut EPIT administration was safe and associated with a modest treatment response after 52 weeks, with the highest responses among younger children. This, when coupled with a high adherence and retention rate and significant changes in immune pathways, supports further investigation of this novel therapy.

Markers of tolerance development to food allergens

IgE-mediated reactions to food allergens are the most common cause of anaphylaxis in childhood. Although allergies to cow's milk, egg, or soy proteins, in contrast to peanut and tree nut allergens, resolve within the first 6 years of life in up to 60% due to natural tolerance development, this process is not well understood. At present, there is no cure or treatment for food allergy that would result in an induction of tolerance to the symptom-eliciting food. Avoidance, providing an emergency plan and education, is the standard of treatment. Oral immunotherapeutic approaches have been proven reasonable efficacy; however, they are associated with high rates of side-effects and low numbers of patients achieving tolerance. Nevertheless, mechanisms that take place during oral immunotherapy may help to understand tolerance development. On the basis of these therapeutic interventions, events like loss of basophil activation and induction of regulatory lymphocyte subsets and of blocking antibodies have been described. Their functional importance at a clinical level, however, remains to be investigated in detail. Consequently, there is eminent need to understand the process of tolerance development to food allergens and define biomarkers to develop and monitor new treatment strategies for food allergy.

Peanut Allergy: New Developments and Clinical Implications

Food allergies have increased in prevalence over the past 20 years, now becoming an important public health concern. Although there are no therapies currently available for routine clinical care, recent reports have indicated that immunotherapies targeting the mucosal immune system may be effective. Oral immunotherapy is conducted by administering small, increasing amounts of food allergen; it has shown promise for desensitizing individuals with peanut, egg, or milk allergies. Sublingual immunotherapy also desensitizes allergic patients to foods-two major studies have examined the effects of sublingual immunotherapy in subjects with peanut allergies. We review the complex nature of IgE-mediated food allergies and the therapies being evaluated in clinical trials. We focus on the diagnosis and management of food allergies and investigational therapies.

Advances in the Treatment of Food Allergy: Sublingual and Epicutaneous Immunotherapy

Food allergies continue to increase in prevalence. Standard care is a strict elimination diet, but life-threatening reactions still occur. Allergen immunotherapy has the most potential in treating food allergy. Subcutaneous immunotherapy has not been adopted into food allergy therapy. Oral immunotherapy has a high rate of adverse reactions. Sublingual immunotherapy (SLIT) uses the tolerogenic environment of the oral mucosa and epicutaneous immunotherapy (EPIT) uses the immune cells of the epidermis to transport antigens to afferent lymph nodes to activate immune responses. SLIT and EPIT can successfully desensitize patients. More research is needed to define optimal doses and administration protocols.

Desensitization for Peanut Allergies in Children

Immunotherapy for peanut allergy has been an exploding topic of study within the last few years. Sublingual, epicutaneous, and oral immunotherapy are being investigated and show promise in the treatment of peanut allergy. Oral immunotherapy has shown the most clinical benefit; however, sublingual and epicutaneous immunotherapy appear to have the most favorable safety profiles. Most studies to date suggest that only a minority of subjects achieve sustained unresponsiveness to peanut after discontinuation of immunotherapy. Recent efforts have been focused on identifying adjunct therapies, such as omalizumab, that may assist patients in achieving peanut desensitization more quickly and with greater success. Several underlying immunologic mechanisms, including a switch from IgE to IgG4 production and induction of T regulatory cells, have been studied although more research is needed to identify reliable biomarkers. This article will describe the immunotherapy approaches that are being investigated to induce peanut desensitization, and highlight the benefits and risks of these therapies that need to be considered before they are ready for routine clinical practice.

Molecular and cellular mechanisms of food allergy and food tolerance

Ingestion of innocuous antigens, including food proteins, normally results in local and systemic immune nonresponsiveness in a process termed oral tolerance. Oral tolerance to food proteins is likely to be intimately linked to mechanisms that are responsible for gastrointestinal tolerance to large numbers of commensal microbes. Here we review our current understanding of the immune mechanisms responsible for oral tolerance and how perturbations in these mechanisms might promote the loss of oral tolerance and development of food allergies. Roles for the commensal microbiome in promoting oral tolerance and the association of intestinal dysbiosis with food allergy are discussed. Growing evidence supports cutaneous sensitization to food antigens as one possible mechanism leading to the failure to develop or loss of oral tolerance. A goal of immunotherapy for food allergies is to induce sustained desensitization or even true long-term oral tolerance to food allergens through mechanisms that might in part overlap with those associated with the development of natural oral tolerance.

Local Side Effects of Sublingual and Oral Immunotherapy

Sublingual immunotherapy (SLIT) is increasingly used worldwide, and several products have been recently registered as drugs for respiratory allergy by the European Medicine Agency and the Food and Drug Administration. Concerning inhalant allergens, the safety of SLIT is overall superior to that of subcutaneous immunotherapy in terms of systemic adverse events. No fatality has been ever reported, and episodes of anaphylaxis were described only exceptionally. Looking at the historical and recent trials, most (>90%) adverse events are "local" and confined to the site of administration. For this reason, a specific grading system has been developed by the World Allergy Organization to classify and describe local adverse events. There is an increasing amount of literature concerning oral desensitization for food allergens, referred to as oral immunotherapy. Also, in this case, local side effects are predominant, although systemic adverse events are more frequent than with inhalant allergens. We review herein the description of local side effects due to SLIT, with a special focus on large trials having a declared sample size calculation. The use of the Medical Dictionary for Regulatory Activities nomenclature for adverse events is mentioned in this context, as recommended by regulatory agencies. It is expected that a uniform classification/grading of local adverse events will improve and harmonize the surveillance and reporting on the safety of SLIT.