Peanut immunotherapy

Palforzia for Peanut Allergy: A Narrative Review and Update on a Novel Immunotherapy

With Palforzia appearing as the first oral immunotherapy for patients with peanut allergy, the present investigation aims to summarize recent clinical trials, the mechanism of dosing, and the real-world usage of this novel therapy. Palforzia offers a new avenue for treating the human allergic response in previous immune modulation refractory patients or patients who have undergone immune environment sensitivity testing, which allows for more specialized treatment. Current studies are focusing on certain age groups that have been shown to be more receptive to treatment. Further, studies are tailoring oral immunotherapy treatment alongside other immune modulators to elicit greater targeted immune tolerance. With an increasing prevalence of patient allergies, many questions remain surrounding the optimization of therapies in reaching therapeutic goals. Overall, Palforzia offers a hopeful treatment for peanut-allergic patients to attenuate their immune response while furthering research in related therapies.

Psychosocial Mediators of Change and Patient Selection Factors in Oral Immunotherapy Trials

Health-related quality of life (HRQL) is influenced by physiological, psychological, and environmental variables and can be best understood by considering the interactions of factors that cut across multiple levels. One of the most important issues relating to treatment in food allergy is to identify, describe, and define predictors that may contribute to modify HRQL outcomes. The research presented demonstrates that measures of HRQL are able to distinguish key features of known groups (e.g. relating to reaction severity, treatment, allergen type/number, expectation of outcome) and delineate impact on hitherto unknown groups (e.g. relating to personality types and coping styles). This heterogeneity may explain why HRQL or other patient-related outcomes may differ in individuals during, or following any treatment or intervention. Patient-reported outcomes are relatively poorly defined to date. Since HRQL has only been studied in relatively few oral immunotherapy trials to date, primarily looking at caregiver HRQL, it is unclear which factors, measures, or subscales are most predictive of short- and/or long-term treatment outcomes for which type of patient, and which time points for measurement are most informative. A standardised protocol that incorporates HRQL and other relevant patient-related outcome measures and agreed definitions of outcomes would allow for the comparison of efficacy of food allergy treatments between centres, trials, or countries. Further evidence-based research aimed at exploring the effects of interventions on outcomes in food allergy is needed, including the influence of patient and parent factors on protocol design. To this end, it is vital that patient-related outcomes such as improved HRQL are seen as a primary outcome and are measured at multiple intervals during the trial duration and beyond. The creative use of methods and designs (both qualitative and quantitative) to better understand the role of HRQL in immunotherapy treatment trials will enable improved modelling of the costs, risks, and benefits of any treatment. Systematic analysis and modelling of antecedent factors, mediators, and outcomes will be important to boost intervention effects and to maximise the overall benefits of treatment.

New modalities of allergen immunotherapy

Allergen immunotherapy is a rapidly evolving field. Although subcutaneous immunotherapy has been practiced for over a hundred years, improved understanding of the underlying immunological mechanisms has led to the development of new, efficacious and better tolerated allergen-derivatives, adjuvants and encapsulated allergens. Diverse routes of allergen immunotherapy - oral, sublingual, epicutanoeus and intralymphatic - are enabling immunotherapy for anaphylactic food allergies and pollen-food allergy syndrome, while improving the tolerability and effectiveness of aeroallergen immunotherapy. The addition of Anti-IgE therapy decreases adverse effects of subcutaneous and oral immunotherapy.

Effects of different thermal processing methods on the structure and allergenicity of peanut allergen Ara h 1

Boiling and frying can alter the structure of peanut allergens and therefore change the IgE-binding capacity of the Ara h 1. In this research, we aim to clarify the connections between structural changes and the allergenicity alteration, and recommend an effective thermal method to minimize the allergenicity of Ara h 1. Anion exchange chromatography was used to isolate Ara h 1 from non/heat-treated peanuts. Ara h 1 in boiled peanuts has a relatively low hydrophobic index, reduced maximum emission wavelength in the fluorescence, less content of α-helix, and the lowest IgE-binding efficiency. On the contrary, Ara h 1 in fried peanuts present a much higher degeneration degree, a red shift in fluorescence, and a decrease in the content of α-helix. These data indicate that boiling can reduce the allergenicity of Ara h 1, thus can be utilized in peanut processing from a security point of view.

Immunotherapy with Native Molecule rather than Hypoallergenic Variant of Pru p 3, the Major Peach Allergen, Shows Beneficial Effects in Mice

Background

The use of hypoallergenic derivatives is considered beneficial to promote the safety and efficacy of allergen-specific immunotherapy. We aimed to assess the efficacy of reduced and alkylated (R/A) Pru p 3, a hypoallergenic folding variant of the major peach allergen, in subcutaneous immunotherapy (SCIT) using a murine model of peach allergy.

Methods and Results

After sensitization with Pru p 3, BALB/c mice received SCIT with Pru p 3 or R/A Pru p 3 and were challenged with Pru p 3. SCIT with Pru p 3, but not with R/A Pru p 3, suppressed anaphylaxis upon the challenge significantly. SCIT with Pru p 3 did not suppress Pru p 3-specific IgE and IgG1 production, but enhanced IgG2a production. In contrast, SCIT with R/A Pru p 3 suppressed IgE and IgG1 production, but enhanced IgG2a production only moderately. The therapeutic efficacy of SCIT with Pru p 3 was associated with induction of IL-10 and IFN-γ.

Conclusion

Hypoallergenic folding variant of Pru p 3 is not likely an efficacious therapeutic component in SCIT of peach allergy. The lower efficacy of R/A Pru p 3 might be attributed to poor antigenicity and/or weak stability due to its unfolded conformation.

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.

Benefit of SLIT and SCIT for Allergic Rhinitis and Asthma

Allergen immunotherapy (AIT) has been in use since more than one century, when Leonard Noon experimentally proved its efficacy in hayfever (Noon, in Lancet 1:1572-3, 1911). Since then, AIT was administered only as subcutaneous injections (SCIT) until the sublingual route (SLIT) was proposed in 1986. The use of SLIT was proposed following several surveys from the USA and UK that repeatedly reported fatalities due to SCIT (Lockey et al. in J Allergy Clin Immunol 75(1): 166, 1985; Lockey et al. in J Allergy Clin Immunol 660-77, 1985; Committee on the safety of medicines. CSM update. Desensitizing vaccines. Br Med J, 293: 948, 1986). These reports raised serious concerns about the safety and the risk/benefit ratio of AIT. Many cases of life-threatening events with SCIT were due to avoidable human errors in administration, but a relevant fraction of them remained unexplained and unpredictable (Aaronson and Gandhi in J Allergy Clin Immunol 113: 1117-21, 2014). Subsequently, in a few years, SLIT gained credibility and was included in the official documents and guidelines (Table 1) (Bousquet et al. in J Allergy Clin Immunol 108(5 Supp):S146-S150, 2001; Canonica et al. in Allergy 64 (Supp 91):1-59, 2009) as a viable alternative to traditional SCIT. Of note, the local bronchial (aerosol) and the intranasal route of administration were attempted after the 1970s as alternatives to SCIT: the bronchial route was soon abandoned due to the poor efficacy and/or side effects, and the local nasal route, although effective and safe, was judged substantially impractical (Canonica and Passalacqua in J Allergy Clin Immunol 111: 437-48, 2003). In contrast to SCIT, SLIT was tested in very large clinical trials (need references), including hundreds of patients and with dose-ranging experimental designs, so that some products (tablets) for grass, mite, and ragweed were officially approved as commercial drugs by regulatory agencies such as the Food and Drug Administration and the European Medicines Agency and the optimal content for the maintenance dose was identified for selected allergens. In parallel, the knowledge on the mechanisms of action of AIT was rapidly refined, leading to further improvements, such as the chemically modified extracts and the use of adjuvants to enhance efficacy and safety. In addition, in the last 10 years, there has been an increasing scientific and clinical interest in AIT applied to food allergies, in particular in children, with the use of orally administered extracts (Albin and Nowak-Węgrzyn in Immunol Allergy Clin North Am 35: 77-100, 2015). The results are so far encouraging, at least for cow's milk, egg, and peanut, although the use of treatment is still restricted to clinical trials or within specialized centers. Finally, the introduction of molecular- or component-resolved diagnosis has allowed detailing the prescription of AIT, by better delineating true sensitization versus cross-reactivity (Canonica et al. in World Allergy Organ J 6(1):17, 2013). This latter point is also in strict relation to the use of recombinant, engineered or highly purified molecules, instead of raw extracts, for the desensitization process.

[Food-induced anaphylaxis - data from the anaphylaxis registry]

Anaphylactic reactions due to food occur in the context of food allergy and, together with venom and drugs, are the most frequent elicitors of severe allergic reactions. In small children the most frequent elicitors of severe allergic reactions according to data from the anaphylaxis registry are hen's egg and milk, whereas in school children peanut and hazelnut are frequent elicitors of allergic reactions. Other frequent elicitors of anaphylactic reactions in childhood are wheat and soy. In adults the most frequent elicitors of severe allergic reactions due to food, based on data from the anaphylaxis registry, are wheat, soy, celery, shellfish and hazelnut. Rare elicitors of food-induced anaphylaxis in German-speaking countries are mustard and cabbage. However, the panel of rare elicitors of food-induced anaphylaxis show regional differences. As of March 2015, 17 cases of fatal anaphylaxis were registered and among these seven were food-induced. Co-factors can either trigger the elicitation of a severe allergic reaction or affect its severity. Among such co-factors are physical activity, the intake of certain drugs, and psychological stress. The data on the role of cofactors is sparse. The management of food-induced anaphylaxis includes acute management according to current guidelines, but also long-term management, which should include educational measures regarding treatment but also information about the food allergen in daily life.

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.

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.

Orphan immunotherapies for allergic diseases

OBJECTIVE

As confirmed by systematic reviews and meta-analyses, allergen immunotherapy is clinically effective in the treatment of allergic diseases. In particular, subcutaneous immunotherapy is a pivotal treatment in patients with severe reactions to Hymenoptera venom, whereas subcutaneous immunotherapy and sublingual immunotherapy are indicated in the treatment of allergic rhinitis and asthma by inhalant allergens. Other allergies related to animal dander (other than cat, which is the most studied), such as dog, molds, occupational allergens, and insects, have also been recognized. For these allergens, immunotherapy is poorly studied and often unavailable. Thus, use of the term orphan immunotherapies is appropriate.

DATA SOURCES

We used MEDLINE to search the medical literature for English-language articles.

STUDY SELECTION

Randomized, controlled, masked studies for orphan immunotherapies were selected. In the remaining cases, the available reports were described.

RESULTS

The literature on food desensitization is abundant, but for other orphan allergens, such as mosquito, Argas reflexus, dog, or occupational allergens, there are only a few studies, and most are small studies or case reports.

CONCLUSION

Orphan immunotherapy is associated with insufficient evidence of efficacy from controlled trials, an erroneous belief of the limited importance of some allergen sources, and the unlikelihood for producers to have a profit in making commercially available extracts (with an expensive process for registration) to be used in few patients. It should be taken into consideration that adequate preparations should be available also for orphan allergens.

Current developments for improving efficacy of allergy vaccines

Allergic diseases are prevalent worldwide. Allergen immunotherapy (AIT) is a current treatment for allergy, leading to modification of the natural course of disease. Mechanisms of efficacy include Treg through release of IL-10 and TGF-β and specific IgG4 blocking antibodies. Subcutaneous and sublingual routes are popular, but uptake is limited by inconvenience and safety concerns. Inclusion criteria limit application to a small proportion of allergic patients. New forms of immunotherapy are being investigated for more efficacious, convenient and safer options with promising advances in recent years. The rationale of reducing vaccine allergenicity to increase safety while improving immunogenicity led to investigation of T-cell epitope-based peptides and recombinant allergen derivatives. Additionally, different routes of administration and adjuvants and adjunct therapies are being explored. This review discusses the current status of AIT and recent advances to improve clinical efficacy, safety and long-term immune tolerance.

Anaphylaxis to food

This article provides a clinically focused review of food-induced anaphylaxis that includes epidemiology, risk factors, allergens, diagnosis, and management. Currently, there is no treatment for food allergy. Dietary avoidance and emergency preparedness are the cornerstones of management. Effective and safe therapies to reduce the risk of serious food-induced reactions are urgently needed, as are reliable biomarkers to predict severity.