The Future of Food Allergy Management: Advancements in Therapies

PURPOSE OF REVIEW

To review current and future treatment options for IgE-mediated food allergy.

RECENT FINDINGS

Recent years have seen major developments in both allergen-specific and allergen-non-specific treatment options, with the first FDA-approved peanut oral immunotherapy (OIT) product becoming available in 2020. In addition to OIT, other immunotherapy modalities, biologics, adjunct therapies, and novel therapeutics are under investigation. Food allergy is a potentially life-threatening condition associated with a significant psychosocial impact. Numerous products and protocols are under investigation, with most studies focusing on OIT. A high rate of adverse events, need for frequent office visits, and cost remain challenges with OIT. Further work is needed to unify outcome measures, develop treatment protocols that minimize adverse events, establish demographic and clinical factors that influence candidate selection, and identify patient priorities.

From Skin to Solution: Exploring Epicutaneous Immunotherapy for Peanut Allergy-A Systematic Review and Meta-Analysis

Peanut allergy is a leading cause of severe food reactions. This meta-analysis evaluates the efficacy and safety of epicutaneous immunotherapy (EPIT) compared to placebo for peanut-allergic individuals. After prospectively registering on PROSPERO, we searched three databases (PubMed, Google Scholar, and Cochrane CENTRAL) and 2 trial registries till September 2023. Analysis was conducted via RevMan where data was computed using risk ratios (RR). The Cochrane Risk of Bias tool and GRADE criteria were used to appraise and evaluate the evidence. From 4927 records, six multicenter randomized placebo-controlled trials comprising 1453 participants were included. The 250 µg EPIT group had a significant increase in successful desensitization compared to placebo (RR: 2.13 (95% C.I: 1.72, 2.64), P < 0.01, I2 = 0%), while the 100 µg EPIT group did not (RR: 1.54 (95% C.I: 0.92, 2.58), P = 0.10, I2 = 0%) (moderate certainty evidence). Moreover, there was a significant increase in local (RR: 1.69 (95% C.I: 1.06, 2.68), P = 0.03, I2 = 89%) and systemic adverse events (RR: 1.75 (95% C.I: 1.14, 2.69), P = 0.01, I2 = 0%) with EPIT. Additionally, individuals administered EPIT have an increased probability of requiring rescue medications like epinephrine (RR: 1.91 (95% C.I: 1.12, 3.28), P = 0.02, I2 = 0%) and topical corticosteroids (RR: 1.49 (95% C.I: 1.29, 1.73), P < 0.01, I2 = 0%) to treat adverse events. The association of adverse events post-treatment including anaphylaxis (RR: 2.31 (95% C.I: 1.00, 5.33), P = 0.05, I2 = 36%), skin/subcutaneous disorders like erythema or vesicles (RR: 0.93 (95% C.I: 0.79, 1.08), P = 0.33, I2 = 0%), and respiratory disorders like dyspnea or wheezing (RR: 0.94 (95% C.I: 0.77, 1.15), P = 0.55, I2 = 0%) with EPIT is inconclusive. EPIT, although effective in desensitization, is linked to an increased risk of adverse events. PROSPERO registration: CRD42023466600.

New Approaches to Food Allergy Immunotherapy

Food allergy is an increasing public health problem in children and adults. In addition to the risk of potentially severe reactions, food allergy can have a significant burden on quality of life, nutrition, cost of living, and social activities. Traditionally, treatment has primarily included strict food allergen avoidance and use of emergency medications to treat an allergic reaction. However, in recent years, there have been significant strides in the advancement of food allergy treatment, including the approval of the first and only approved therapy (peanut oral immunotherapy) for food allergy in 2020. Clinical trials have primarily focused on food allergen immunotherapy (oral, epicutaneous, sublingual). Building off of a foundation of promising data supporting the efficacy of food oral immunotherapy and our greater understanding of the underlying mechanism of immunotherapy, newer approaches, including alternative routes of delivery, adjuncts to therapy, modified allergens, and utilization in younger patients, aim to provide safer and more effective treatment approaches to the millions of patients burdened by food allergy.

Flex-IT! Applying "Platform Trials" Methodology to Immunotherapy for Food Allergy in Research and Clinical Practice

There is an increasing trend in the management of food allergy toward active treatment using allergen immunotherapy (AIT). Although AIT is efficacious, treatment-related adverse events are common, particularly with oral immunotherapy in those with high levels of allergen-specific IgE sensitization. In clinical practice, these adverse events inevitably create challenges: clinicians and patients routinely face decisions whether to alter the dose itself, the frequency of dosing, and the pace of escalation, or indeed discontinue AIT altogether. Flexibility is therefore needed to adapt treatment, particularly in clinical practice, so that participants are "treated-to-target." For example, this may entail a significant change in the dosing protocol or even switching from one route of administration to another in response to frequent adverse events. We refer to this approach as flexible immunotherapy. However, there is little evidence to inform clinicians as to what changes to treatment are most likely to result in treatment success. Classical clinical trials rely, by necessity, on relatively rigid updosing protocols. To provide an evidence base to optimize AIT, the food allergy community should adopt adaptive platform trials, where a "master protocol" facilitates more efficient evaluation, including longer-term outcomes of multiple interventions. Within a single clinical trial, participants are able to switch between different treatment arms; interventions can be added or dropped without compromising the integrity of the trial. Developing platform trials for food AIT may initially be costly, but they represent a significant opportunity to grow the evidence base (with respect to both treatment outcomes and biomarker discovery) at scale. In addition, they could help understand longitudinal disease trajectories that are difficult to study in clinical trials for food allergy due to the time needed to demonstrate changes in efficacy. Finally, their adoption would achieve greater collaboration and consistency in approaches to proactive management of food allergy in routine clinical practice. As a community, we need to actively pursue this with funders and established research collaborations to deliver the very best outcomes for our patients and their families.

Sustained antigens delivery using composite microneedles for effective epicutaneous immunotherapy

Allergen-specific immunotherapy (SIT) is a desirable way of therapy for various allergic diseases such as food allergy (FA). However, frequent visits for more than 3 years and potential adverse effects often hinder patient compliance. Recently, many researchers started focusing on microneedles (MNs) as a new method for SIT. In this study, we proposed an implantable MNs system produced by a two-step casting process, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible polyvinyl alcohol (PVA) pedestal. Different from PVA, silk fibroin hydrogel has preferable vaccine release ability in vivo and in vitro. Once MNs are inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min and implant the OVA-loaded silk microneedle tips in dermal layer as a sustained antigen depot, thus inducing long-lasting immune response for at least 2 weeks. After receiving 3 doses of MN-based immunotherapy, the immune response in OVA-sensitized mice was successfully suppressed, with no apparent side effects. Compared to conventional subcutaneous immunotherapy (total dose of 150 [Formula: see text]g), MN immunotherapy ameliorated systemic anaphylaxis more effectively even at a lower dose (total dose of 30 [Formula: see text]g), demonstrating the antigen dose-sparing potential of the proposed MNs. Moreover, due to the prolonged release effect of silk-PVA composite MNs, the frequency of immunotherapy can be significantly reduced. To sum up, through prolonged skin exposure to antigen, this implantable designed MN may offer a new therapeutic strategy for FA treatment with significant improvements in efficacy and convenience. Schematic illustration of silk-PVA composite microneedles, consisting of OVA (antigen)-loaded silk microneedles and a dissolvable, flexible PVA pedestal. Once inserted into the skin, the PVA pedestal can dissolve in the interstitial fluid of the excised skin within 5 min. Subsequently, the OVA-loaded silk microneedle tips were implanted in the dermal layer as a sustained antigen depot and induced long-lasting immune response. This MNs-based immunotherapy can significantly modulate the Th1/Th2 imbalance of sensitized mice.

Efficacy and safety of peanut epicutaneous immunotherapy in patients with atopic comorbidities

Background

Co-occurring atopic conditions are common in children with peanut allergy. As such, it is important to examine the safety and efficacy of epicutaneous immunotherapy with Viaskin Peanut 250 μg patch (VP250) in peanut-allergic children with these conditions.

Objective

We sought to compare efficacy and safety of VP250 versus placebo in peanut-allergic children with/without ongoing atopic conditions at baseline, including asthma, atopic dermatitis/eczema, or concomitant food allergy.

Methods

A subgroup analysis of peanut-allergic children aged 4 to 11 years enrolled in PEPITES (12 months) and REALISE (6 months) randomized, placebo-controlled, phase 3 trials was conducted. The efficacy outcome measure was the difference in prespecified responder rate between placebo and VP250 groups at month 12 based on eliciting dose of peanut protein using double-blind, placebo-controlled food challenge in PEPITES. Safety profiles were evaluated by baseline concomitant disease subgroup in all randomized subjects who received 1 or more dose of the study drug in PEPITES and REALISE pooled data.

Results

Responder rates were significantly (P < .05, all comparisons) greater with VP250 compared with placebo treatment regardless of whether subjects had other atopic conditions. Safety and tolerability profiles were generally similar across subgroups, with no new safety concerns detected. A trend for both higher responder rates and rates of local reactions was observed in subjects with baseline atopic dermatitis versus those without. In subjects with concomitant food allergy at baseline, higher rates of treatment-emergent adverse events, but not study discontinuations or overall rates of anaphylaxis, were observed.

Conclusions

The results support the safety and efficacy of VP250 for treating peanut-allergic children with or without concomitant atopic conditions.

[The route is the destination-novel forms of application of allergen immunotherapy]

Allergen immunotherapy (AIT) is the only causal therapy of IgE-mediated allergies if allergen avoidance is not feasible. Already well established are subcutaneous (SCIT) and sublingual (SLIT) allergen application, and recently the first oral immunotherapy (OIT) for treating peanut allergy was approved. Interesting and promising new forms of allergen administration are intralymphatic (ILIT) and epicutaneous (EPIT) immunotherapy. Immunologic and clinical efficiency in terms of tolerance induction have been investigated in animal and clinical studies, including the first phase 3 studies. The findings as well as advantages and disadvantages, potential risks and challenges that still have to be addressed before routine clinical application can be envisioned will be comprehensively presented and discussed.

Aggravation of Food Allergy by Skin Sensitization via Systemic Th2 Enhancement

BACKGROUND

Recently, the relationship between antigen contact via skin (skin sensitization) and the development of food allergies has gained increasing attention. However, few studies have examined the effects of skin sensitization on healthy skin.

OBJECTIVE

To examine the effect of sensitization in healthy skin on IgE and cytokine production during food allergy development.

METHODS

The effect of skin sensitization on food allergy was evaluated using DO11.10 mice whose T cells express ovalbumin (OVA)-specific T-cell receptors. OVA was applied to the back skin of mice dehaired by various methods, and then food allergy was induced by providing them with an OVA-containing diet. OVA-specific IgE production in the sera and decreases in body temperature due to anaphylactic reaction were measured as indicators of food allergy. In addition, IL-4 production and proliferation of splenocytes were measured in mice with food allergy after skin sensitization.

RESULTS

Skin sensitization in healthy skin increased IgE production and exacerbated anaphylactic symptoms induced by ingesting the antigen. Moreover, skin sensitization enhanced IL-4 production from splenocytes during the onset of food allergy. In contrast, oral tolerance was induced even after establishing skin sensitization.

CONCLUSION

Skin sensitization temporarily exacerbated food allergy by enhancing systemic Th2 responses. These findings will help identify the mechanisms involved in food allergy and help develop treatments.

Improvements in Quality of Life in Children Following Epicutaneous Immunotherapy (EPIT) for Peanut Allergy in the PEPITES and PEOPLE Studies

BACKGROUND

Food allergy quality of life (FAQL) is impaired in children with peanut allergy. Food Allergy Quality of Life Questionnaires (FAQLQs) provide disease-specific insight into the burden of peanut allergy and potential FAQL changes after peanut immunotherapy.

OBJECTIVE

To examine FAQL changes in children after treatment with epicutaneous immunotherapy for peanut allergy (250 μg, daily epicutaneous peanut protein; DBV712 250 μg).

METHODS

FAQL was prospectively measured using the FAQLQ parent proxy form (Food Allergy Quality of Life Questionnaire-Parent Proxy Form [FAQLQ-PF], for children aged ≤12 years) and child form (Food Allergy Quality of Life Questionnaire-Child Form [FAQLQ-CF], child rated if aged ≥8 years) during the 12-month double-blind, randomized, controlled Peanut EPIT Efficacy and Safety Study (PEPITES) trial and the initial 12 months of the open-label PEPITES Open Label Extension Study (PEOPLE) follow-up study. Data were analyzed for between-group differences after treatment unblinding.

RESULTS

FAQLQs from placebo participants (FAQLQ-PF: 96; FAQLQ-CF: 47) and treatment group participants (FAQLQ-PF: 209; FAQLQ-CF: 105) were analyzed. Twenty-four-month global FAQL scores (FAQLQ-PF/FAQLQ-CF) were significantly improved in the treatment group versus the placebo group (least squares mean, 0.34, P = .008, and 0.46, P = .023, respectively). At 24 months, there was significant FAQLQ-PF score improvement in participants initially randomized to treatment who met the efficacy primary end point (n = 74; least squares mean, 0.55; P < .001) and in participants with any eliciting dose increase (n = 127; least squares mean, 0.66; P < .001). FAQLQ-PF improvements were observed in social dietary limitations (P = .002), food-related anxiety (P = .029), and emotional impact (P = .048) domains. FAQLQ-CF improvements were observed in risk of accidental exposure (P = .002) and allergen avoidance (P = .04) domains. Nearly all outcomes met a nontreatment context minimal clinically important difference previously cited for FAQLQ.

CONCLUSIONS

Epicutaneous immunotherapy treatment was observed to be associated with significant global and domain-specific FAQL improvement (FAQLQ-PF/FAQLQ-CF), largely driven by increases in eliciting dose, in children with peanut allergy.

Therapeutic perspectives in food allergy

BACKGROUND

In the last twenty years, several studies have been conducted in the search for new therapeutic strategies in patients with food allergy; in particular, after the failure of injection immunotherapy, three different routes of administration, oral immunotherapy (OIT), sublingual immunotherapy (SLIT), and epicutaneous immunotherapy (EPIT), have been tested. The aim of this manuscript is to review OIT, SLIT, and EPIT clinical trials on food allergies and to suggest advantages and limits of the different routes of immunotherapy administration.

MAIN BODY

Of the three different routes of immunotherapy used in the treatment of food allergy, OIT is, at present, the only one actually able to induce an increase in tolerance in the majority of patients. However, its use is affected by serious secondary effects, such as major abdominal symptoms and anaphylaxis. The combination with omalizumab reduces the percentage of serious side effects. There are not many studies with SLIT for food allergy, but they have nevertheless shown that it is possible to obtain an increase in tolerance; however, this increase is modest in comparison with that obtained by OIT. EPIT, performed through the diffusion of allergens on intact skin, is the most recent form of immunotherapy. Although there are many works on EPIT carried out in laboratory animals, only few clinical studies have been published in humans. EPIT, unlike OIT and SLIT, is not responsible for systemic secondary effects such as anaphylaxis and eosinophilic oesophagitis but only for local and mild effects in areas where the devices are applied. Moreover, EPIT is characterized by high patient adherence.

CONCLUSION

OIT seems to have a prevalent application in patients who do not report previous symptoms of systemic or gastroenteric anaphylaxis, while SLIT and EPIT, in particular, could be more preferentially used in patients with a risk of anaphylaxis.

Dc-specific aptamer decorated gold nanoparticles: A new attractive insight into the nanocarriers for allergy epicutaneous immunotherapy

Recently, the main goal of many allergy epicutaneous immunotherapy (EPIT) studies is to enhance the allergen delivery through the intact skin. Therefore, applying new strategies for tackling this issue are inevitable. For this purpose, ten groups of Che a 2-sensitized BALB/c mice were epicutaneously treated for a 6-week period with the rChe a 2-GNPs-Aptamer, rChe a 2-GNPs-Aptamer + skin-penetrating peptides (SPPs), rChe a 2-GNPs, rChe a 2, GNPs, and PBS. Afterward, the serum IgE and IFN-γ, TGF-β, IL-10, IL-4, IL-17a cytokine production, NALF analysis, and lung/nasal histological examinations were performed. The present study results demonstrate that, EPIT in aptamer treated groups had a significant increase of IFN-γ, TGF-β, and IL-10 concentrations and a significant decrease of IgE, IL-4, and IL-17a concentrations as well as NALF infiltrated immune cell count compared to the non-targeted ones. In addition, SPPs led to more significant improvement of immunoregulatory parameters, especially IL-10 cytokine. Accordingly, the targeted-GNPs with DC-specific aptamers could act as an efficient approach for the improvement of EPIT efficacy compared to the free allergen. Moreover, the application of SPPs might be considered as a useful tool in achieving a successful EPIT with lower doses of allergen at a shorter duration of the treatment.

The Efficacy and Safety of Epicutaneous Immunotherapy for Allergic Diseases: A Systematic Review and Meta-Analysis

OBJECTIVES

To systematically review the effect and safety of epicutaneous immunotherapy (EPIT) for allergic diseases.

METHODS

We searched PubMed, EMBASE, Cochrane Central Register of Controlled Trials, China National Knowledge Infrastructure, CQ VIP Database, Wanfang Data, and international trial register from their inception to July 29, 2019, without language restrictions, for randomized controlled trials (RCTs) that compared EPIT versus no EPIT for allergen-triggered allergic reactions. We assessed certainty of evidence by the GRADE approach.

RESULTS

Ten RCTs with 1,085 participants (aged from 10 months to 65 years) comparing EPIT with placebo for peanut, cow milk, or grass-pollen allergy met the eligibility criteria. A substantial benefit in terms of desensitization in EPIT group was more likely for peanut or cow milk protein allergy (risk ratio [RR] 2.34, 95% CI 1.69-3.23; I2 = 0%; high certainty evidence). EPIT increased local-treatment-related adverse events (L-TRAE; RR 1.56, 95% CI 1.03-2.36; I2 = 82%; moderate certainty evidence). But there were no significantly increased risk of any TRAEs (low certainty evidence) or systemic-TRAEs (S-TRAEs; very low certainty evidence) in EPIT group. The incidence rate of serious AEs, the use of rescue medications, and anaphylactic reactions stratified by organ systems including skin and mucosa, eyes and upper respiratory, lower respiratory, and gastrointestinal system in EPIT group were similar to placebo group. In subgroup analysis, desensitization of EPIT was significantly effective in peanut allergy (RR 2.29, 95% CI 1.64-3.21; I2 = 0%) and children <12 years (RR 2.85, 95% CI 1.92-4.24; I2 = 0%) with high certainty evidence. Only epicutaneous grass-pollen immunotherapy significantly increased the risk of S-TRAE (RR 4.65, 95% CI 1.10-19.64; I2 = 0%).

CONCLUSION

The systematic review suggests that EPIT might induce desensitization in peanut allergy and an increased risk of local AEs. These findings should be interpreted with caution owing to the limited study and heterogeneity. More data in the older (children ≥12 years and adults) and other allergic diseases are needed.

Delivery of allergen powder for safe and effective epicutaneous immunotherapy

BACKGROUND

More effective and safer immunotherapies to manage peanut allergy are in great demand despite extensive investigation of sublingual/oral immunotherapy and epicutaneous immunotherapy (EPIT) currently in the clinics.

OBJECTIVE

We sought to develop a powder-laden, dissolvable microneedle array (PLD-MNA) for epidermal delivery of powdered allergens and to evaluate the efficacy of this novel EPIT in peanut-sensitized mice.

METHODS

PLD-MNA was packaged with a mixture of powdered peanut allergen (PNA), 1,25-dihydroxyvitamin D₃ (VD3), and CpG. Its epidermal delivery and therapeutic efficacy were evaluated alongside PNA-specific forkhead box P3-positive regulatory T cells and IL-10⁺ and TGF-β1⁺ skin-resident macrophages.

RESULTS

PLD-MNA was successfully laden with PNA/VD3/CpG powder and capable of epidermal delivery of most of its content 1 hour after application onto intact mouse skin concomitant with no significant leakage into the circulation or skin irritation. PLD-MNA-mediated EPIT substantially reduced clinical allergy scores to 1 from 3.5 in sham control mice (P < .001) after 6 treatments accompanied by lower levels of PNA-specific IgE and intestinal mucosal mast cells and eosinophils over sham treatments. Moreover, in comparison with allergens administered intradermally, powdered allergens delivered by means of PLD-MNA preferentially attracted immunoregulatory macrophages and stimulated the cells to produce IL-10, TGF-β, or both at the immunization site, which might account for increased numbers of regulatory T-like cells in lymph tissues in association with systemic tolerance. PNA/VD3/CpG-laden PLD-MNA was safe and required only 6 treatments and one fifth of the PNA adjuvant dose, with improved outcomes when compared with 12 conventional intradermal immunotherapies.

CONCLUSIONS

PLD-MNA holds great promise as a novel, safe, effective, and self-applicable modality to manage IgE-mediated allergies.

The Role of Shared Decision Making in Pediatric Food Allergy Management

Shared decision making was first highlighted in a report by the Institute of Medicine in 2001. The primary aim of this initiative was to improve the quality of care provided to patients in the United States by creating a health care system that is safe, effective, efficient, and equitable. Currently, medical decision making is based on a patient-centered approach, with the individual's preferences, needs, and values guiding optimal care. Patients are frequently faced with various treatment choices with no absolute guarantee of any desired outcome and no clear indication of the "best or least worse" option. In fact, in healthcare, each of these options usually has potential trade-offs and outcomes. The process of how to choose a particular option becomes a discussion where the clinician and the patient have to jointly review the medical evidence, but also the patient's openness and preference for balancing particular attributes of the treatment (both positive and negative). Shared decision making is important for chronic diseases that require long-term management, such as most allergic conditions, including food allergies. The landscape of food allergies has changed considerably in recent years with multiple and significant scientific advances in both diagnostics and treatment, providing an ideal field for the use of shared decision making. For the purposes of this review, we will discuss different areas of food allergy management within a single complex case, focusing on the role of shared decision making.

Skin as an immune organ and clinical applications of skin-based immunotherapy

Background

The prevalence of food allergy is increasing, and allergen avoidance continues to be the main standard of care. There is a critical need for safe and effective forms of immunotherapy for patients with food allergy as well as other allergic diseases.

Findings

The skin is a multifunctional organ with unique immunologic properties, making it a favorable administration route for allergen-specific immunotherapy. Epicutaneous immunotherapy (EPIT) takes advantage of the skin’s immune properties to modulate allergic responses and is thus one of the allergen-specific immunotherapy approaches currently being investigated for food allergy. Advances made in the understanding of how epicutaneously applied proteins interact with the immune system and in the technology for facilitating such interactions offer many opportunities for clinical application. Research has shown that allergen delivered to intact skin via EPIT is taken up in the superficial layers of the skin by Langerhans cells, avoiding passive movement of allergen through the dermis and limiting systemic circulation. EPIT brings about allergen desensitization by activating a population of regulatory T cells (Tregs) with unique properties and the potential for inducing a sustained effect as well as the possibility (seen in animal models) for protection against further sensitizations. Several clinical trials investigating the therapeutic efficacy of EPIT for treatment of peanut allergy have been completed, as well as a Phase 2 trial for treatment of milk allergy.

Conclusions

Taken together, the reviewed literature supports the concept that EPIT activates the natural desensitization pathway of the skin, offering a progressive, possibly sustained response. EPIT offers a potential alternative for allergen immunotherapy that is less invasive and carries a lower risk for systemic reactions than oral immunotherapy.

Epicutaneous immunotherapy in rhino-conjunctivitis and food allergies: a review of the literature

Background

Epicutaneous immunotherapy (EPIT) is a new way of allergen administration that has a high rate of adherence and safety. The aim of this manuscript is to review clinical trials on EPIT for respiratory and food allergies published in the last 10 years, taking into account how different variables (i.e., dose, patch application duration, skin preparation, and efficacy and safety evaluation) have influenced study results.

Main body

From a review of the literature, we identified eight placebo-controlled, double-blind trials conducted on children and adults, including four studies on grass pollen rhino-conjunctivitis, one on cow’s milk allergy and three on peanut allergy. Different methods for skin pre-treatment, such as skin abrasion and tape stripping or stratum corneous hydration by an occlusive system, different endpoints and cumulative allergen doses, and different durations of patch application and tape stripping, were used in the rhino-conjunctivitis studies. A visual analogue system was used for the efficacy evaluation. Several local skin reactions (eczema) and some systemic adverse reactions were reported at higher rates in the active group compared to placebo in one study, but this was not shown by other authors. Local eczema reactions were correlated to the times for applying the tape stripping, while systemic side effects were correlated to the deepness of scraping. In the food allergy trials, differences in the food challenge thresholds, endpoints and allergen sites of the cutaneous patch application influenced the study results. A slight dose-dependent efficacy was found in the peanut allergy studies, which was confirmed by a more significant increase in the following progressive open study. Few adverse events and high adherence in all of the food allergen trials were reported.

Conclusions

Overall, the EPIT study results, even if they were affected by great heterogeneity among the methodologies applied, have shown not only the high safety and adherence with this kind of immunotherapy but also suggested the possibility for obtaining definitive evidence of the efficacy of EPIT, especially for food allergies.

Antigen Uptake by Langerhans Cells Is Required for the Induction of Regulatory T Cells and the Acquisition of Tolerance During Epicutaneous Immunotherapy in OVA-Sensitized Mice

The skin is a major immunologic organ that may induce protection, sensitization or tolerance. Epicutaneous immunotherapy (EPIT) has been proposed as an attractive strategy to actively treat food allergy and has been shown to induce tolerance in sensitized mice through the induction of Foxp3⁺ regulatory T cells (Tregs), especially CD62L⁺ Tregs. Among immune cells in the skin, dendritic cells are key players in antigen-specific immune activation or regulation. The role of different populations of skin DCs in tolerance induction remains to be elucidated. Using OVA-sensitized BALB/c mice, we demonstrated that the application of a patch containing OVA-A647 to the skin resulted in allergen uptake by Langerhans cells (LCs) and CD11b⁺ dermal cDC2 and subsequent migration into skin draining lymph nodes. These 2 populations induced Foxp3 expression in CD4⁺ cells in vitro. Only LCs induced LAP⁺ cells and CD62L⁺ Tregs. Using Langerin-eGFP-DTR mice, we analyzed the role of LCs in the mechanisms of tolerance induction by EPIT in vivo. Following complete depletion of LCs, a dramatic decrease in the number of OVA⁺ DCs and OVA⁺ CD11b⁺ dermal cDC2 was observed in skin draining lymph nodes 48 h after epicutaneous application. Likewise, 2 weeks of EPIT in non-depleted mice induced Foxp3⁺ Tregs, especially CD62L⁺, and LAP⁺ Tregs in skin draining lymph nodes and spleen, whereas no induction of Tregs was observed in LC-depleted mice. Following 8 weeks of treatment, EPIT-treated mice showed significant protection against anaphylaxis accompanied by a significant increase of Foxp3⁺ Tregs, especially CD62L⁺ Tregs, which was not seen in the absence of LCs. In summary, although both LCs and CD11b⁺ dermal cDC2s could induce regulatory T cells, the absence of LCs during EPIT impaired treatment efficacy, indicating their crucial role in skin-induced tolerance.

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.

Advances in Food Allergy

Food allergy has been increasing in prevalence for the last few decades, and numerous studies have evaluated ways of improving the allergy practitioner's ability to accurately diagnose patients who are truly food allergic, rather than sensitive but able to tolerate food. Once diagnosed, the current standard treatment is food elimination and avoidance, but other potential treatment options like oral immunotherapy, sublingual immunotherapy, and epicutaneous immunotherapy are becoming promising alternatives. Due the health care costs and potential for life-threatening adverse reactions, much attention has been given to the prevention of food allergies, resulting a shift in recent guideline recommendations.

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.

Current and Emerging Therapies for IgE-Mediated Food Allergy

Food allergies are a growing clinical problem leading to increased health care utilization and decreases in patient quality of life. Current treatment recommendations include strict dietary avoidance of the offending food as well as use of self-injectable epinephrine in case of accidental exposure with allergic reaction. Although many individuals will eventually outgrow their food allergies, a substantial number will not. Significant effort has been made to find novel treatments that protect patients from food-triggered reactions as well as to develop immune-modulating therapies that could lead to tolerance. In this review, three therapies that have shown the most promise for the treatment of food allergies are highlighted: oral immunotherapy, sublingual immunotherapy, and epicutaneous immunotherapy.

Epicutaneous immunotherapy induces gastrointestinal LAP+ regulatory T cells and prevents food-induced anaphylaxis

BACKGROUND

The attempt to induce oral tolerance as a treatment for food allergy has been hampered by a lack of sustained clinical protection. Immunotherapy by nonoral routes, such as the skin, may be more effective for the development of maintained tolerance to food allergens.

OBJECTIVE

We sought to determine the efficacy and mechanism of tolerance induced by epicutaneous immunotherapy (EPIT) in a model of food-induced anaphylaxis.

METHODS

C3H/HeJ mice were sensitized to ovalbumin (OVA) orally or through the skin and treated with EPIT using OVA-Viaskin patches or oral immunotherapy using OVA. Mice were orally challenged with OVA to induce anaphylaxis. Antigen-specific regulatory T (Treg)-cell induction was assessed by flow cytometry using a transgenic T-cell transfer model.

RESULTS

By using an adjuvant-free model of food allergy generated by epicutaneous sensitization and reactions triggered by oral allergen challenge, we found that EPIT induced sustained protection against anaphylaxis. We show that the gastrointestinal tract is deficient in de novo generation of Treg cells in allergic mice. This defect was tissue-specific, and epicutaneous application of antigen generated a population of gastrointestinal-homing LAP⁺Foxp3^- Treg cells. The mechanism of protection was found to be a novel pathway of direct TGF-β-dependent Treg-cell suppression of mast cell activation, in the absence of modulation of T- or B-cell responses.

CONCLUSIONS

Our data highlight the immune communication between skin and gastrointestinal tract, and identifies novel mechanisms by which epicutaneous tolerance can suppress food-induced anaphylaxis.

A practical view of immunotherapy for food allergy

Food allergy is common and sometimes life threatening for Korean children. The current standard treatment of allergen avoidance and self-injectable epinephrine does not change the natural course of food allergy. Recently, oral, sublingual, and epicutaneous immunotherapies have been studied for their effectiveness against food allergy. While various rates of desensitization (36% to 100%) and tolerance (28% to 75%) have been induced by immunotherapies for food allergy, no single established protocol has been shown to be both effective and safe. In some studies, immunologic changes after immunotherapy for food allergy have been revealed. Adverse reactions to these immunotherapies have usually been localized, but severe systemic reactions have been observed in some cases. Although immunotherapy cannot be recommended for routine practice yet, results from recent studies demonstrate that immunotherapies are promising for the treatment of food allergy.

State of the art on food allergen immunotherapy: oral, sublingual, and epicutaneous

IgE-mediated food allergy is a global health problem that affects millions of persons and affects every aspect of life for the patient. Developing effective treatment strategies to augment current practice standards of strict dietary avoidance of antigens and availability of self-injectable epinephrine has been a major focus of research teams, advocacy groups, funding agencies, and patients and their families. Significant progress has been made through the development of allergen-specific immunotherapy encompassing 3 major forms of treatment: oral, sublingual, and epicutaneous immunotherapy. These therapies are in various stages of clinical investigation, with some successes noted in clinical outcomes and modulation of immune mechanisms toward effective therapy. Here we review recent progress and areas of concern for the role of these forms of immunotherapy as an emerging treatment for food allergy.