Sublingual-swallow immunotherapy (SLIT) in patients with asthma due to house-dust mites: a double-blind, placebo-controlled study

The evidence for commercial house dust mite immunotherapy products: A pragmatic systematic review with narrative synthesis

House dust mite (HDM) allergen immunotherapy (AIT) has an established role in the treatment of perennial allergic rhinitis (AR) and allergic asthma (AA) triggered by HDM sensitization. We aimed to identify all double-blind, randomized, placebo-controlled trials of HDM AIT for the treatment of AR and AA in humans and to summarize the evidence for AIT products that are currently manufactured and available for clinical use. A total of 56 eligible double-blind, randomized, placebo-controlled trials of HDM AIT for the treatment of AA and/or AR in humans fit the inclusion criteria and investigated a total of 14 commercial AIT products; together, the 56 studies enrolled a total of 14,619 patients. Of the 56 studies, 39 studies investigated the current manufacturer-recommended maintenance dose (MRMD) of the product, and 17 investigated other doses. We identified 39 studies (12,539 patients randomized) for 8 sublingual immunotherapy (SLIT) products and 17 studies (2,080 patients randomized) for subcutaneous immunotherapy products. For AR, 3 products, the ALK 12 standardized-quality (SQ-HDM) SLIT tablet, the ALK 6 SQ-HDM tablet, and the SG 300 index of reactivity SLIT tablet, had both dose-finding studies (DFSs) and phase III definitive studies (DSs) to demonstrate efficacy of the MRMD of the product. For AA, 2 products, the ALK 12 SQ-HDM SLIT tablet and the ALK 6 SQ-HDM tablet, had both DFSs and DSs for the MRMD. No subcutaneous immunotherapy product had a paired DFS and DS supporting the MRMD. A total of 30 studies of products no longer commercially manufactured were excluded. This study will help to inform clinical care and product selection for the treatment of HDM-induced AR and AA.

Standardization of clinical outcomes used in allergen immunotherapy in allergic asthma: An EAACI position paper

INTRODUCTION

In allergic asthma patients, one of the more common phenotypes might benefit from allergen immunotherapy (AIT) as add-on intervention to pharmacological treatment. AIT is a treatment with disease-modifying modalities, the evidence for efficacy is based on controlled clinical trials following standardized endpoint measures. However, so far there is a lack of a consensus for asthma endpoints in AIT trials. The aim of a task force (TF) of the European Academy of Allergy and Clinical Immunology (EAACI) is evaluating several outcome measures for AIT in allergic asthma.

METHODS

The following domains of outcome measures in asthmatic patients have been evaluated for this position paper (PP): (i) exacerbation rate, (ii) lung function, (iii) ICS withdrawal, (iv) symptoms and rescue medication use, (v) questionnaires (PROMS), (vi) bronchial/nasal provocation, (vii) allergen exposure chambers (AEC) and (viii) biomarkers.

RESULTS

Exacerbation rate can be used as a reliable objective primary outcome; however, there is limited evidence due to different definitions of exacerbation. The time after ICS withdrawal to first exacerbation is considered a primary outcome measure. Besides, the advantages and disadvantages and clinical implications of further domains of asthma endpoints in AIT trials are elaborated in this PP.

CONCLUSION

This EAACI-PP aims to highlight important aspects of current asthma measures by critically evaluating their applicability for controlled trials of AIT.

Can development of asthma and bronchial hyperreactivity be reduced by subcutaneous immunotherapy in adult patients with allergic rhinitis?

BACKGROUND

Allergic rhinitis can be associated with bronchial hyperreactivity (BHR) and create an increased risk for allergic asthma development. We aimed to investigate the effects of subcutaneous immunotherapy (SCIT) on BHR and asthma development in adult patients with allergic rhinitis.

METHODS

The retrospective case-control study was carried out between November 2018 and May 2019 in Süreyyapaşa Chest Diseases and Thoracic Surgery Training and Research Hospital. In this study, data was recorded for patients with a mite and/or grasses/cereals pollen allergy who were tested for BHR before planned SCIT, and who had allergic rhinitis, with or without asthma. The SCIT group was selected as those who received SCIT for at least one year. The control group was selected from those who were scheduled to receive SCIT but were waived and still receiving medication. Symptom scores, prick test results, PC20 levels (methacholine challenge that is a provocative concentration causing a 20% fall in FEV1), and the presence of asthma were recorded and compared with data from at least one year after treatment.

RESULTS

A total of sixty-eight subjects (22 males, 46 females; mean age 40.54 ± 12.27 years; SCIT: 40, Control: 28) were enrolled.Although the changes in log PC20 levels were not statistically significant in both SCIT and control groups after an average of 30-35 months of treatment, it was found to be significant in favor of the SCIT group when two groups were compared in terms of the change in log PC20 (p = 0.026). The development and improvement of asthma were not significantly different between the SCIT and control group but tended to increase in the control group. The percentage of patients with progressed/BHR was significantly higher in the controls (70.6% vs. 38.1%, p = 0.046).

DISCUSSION

In our real life study we have demonstrated the preventative effect of SCIT on BHR, but not on asthma developmen.

Study on Effects of Sublingual Immunotherapy in Allergic Rhinitis Patients

Allergic Rhinitis is one of the most common allergic disease and characterized by sneezing, rhinorrhea, nasal congestion and nasopharyngeal itching. The initial management includes pharmacological treatment and the patients who are refractory to pharmacological treatment are then reffered for immunotherapy. SLIT has been widely used for treatment of allergic rhinitis and has proven its clinical efficacy. The objective of the present study was to assess the clinical effects, safety and tolerability of sublingual immunotherapy (SLIT) among the patients suffering from allergic rhinitis. The study was conducted from Aug 2018 to April 2021 and 40 patients with convincing history, positive skin prick test to one or more allergen extracts were recruited. SLIT was conducted with antigens (mix), namely dust mites, tree pollens, grass pollens and weed pollens in patients of allergic rhinitis for 1 year. There was significant improvement in quality of life and symptoms severity(Nasal and Non-Nasal) from base line to end of 1 year. SLIT lowers the total IgE, absolute eosinophilic count and medication requirement. Sublingual Immunotherapy for specific allergens decreases clinical symptoms in patients with allergic rhinitis and sensitivity to multiple allergen.

Current advances in house dust mite allergen immunotherapy (AIT): Routes of administration, biomarkers and molecular allergen profiling

Allergy to house dust mites (HDM) is a perennial respiratory disease that affect more than half a billion people worldwide. Dermatophagoides pteronyssinus and D. farinae, two HDM species, are major sources of indoor allergens triggering allergic inflammation. Although symptomatic drugs are widely used to block the allergic reaction, allergen immunotherapy is the only curative treatment of IgE-mediated type I respiratory allergies. In this article, we review recent advances in various routes of allergen immunotherapy. We particularly focus on subcutaneous (SCIT) and sublingual (SLIT) immunotherapy, used as a reference therapy since they have transformed allergic treatments by improving symptoms (asthma and rhinitis) as well as the quality of life of patients. We also highlight recent data in more exploratory routes (i.e., oral, intralymphatic, epicutaneous and intradermal) and discuss respective advantages of various route, as well as their foreseen modes of action. Finally, we provide an update on biomarkers as well as on the relevance of the molecular profiling of allergic individuals related to treatment efficacy or asthma prediction.

Immune mechanisms induced by sublingual immunotherapy in allergic respiratory diseases

Allergic respiratory diseases (ARDs) are still a major burden on global public health. Sublingual immunotherapy (SLIT) is a mode of allergen immunotherapy (AIT) which involves administration of the allergen under the tongue, and benefits from tolerogenic properties of the oral mucosa. Studies revealed reduced levels of eosinophilia and eosinophil-dominated inflammation in airways of both animals and humans after SLIT. SLIT was also suggested to lower basophil responsiveness and innate lymphoid cell-2 function in blood samples collected from patients with ARD. Moreover, apart from shifting pathogenic type 2 (TH2) to a type 1 (TH1) and protective regulatory (Treg) polarization of helper T-cell immune response, antibody isotype switch from IgE to IgG1, IgG2, IgG4 and IgA was also reported in patients with ARD receiving SLIT. Today, the literature on SLIT-mediated activities is still scarce and more studies are required to further enlighten the mechanisms utilized by SLIT for the induction of tolerance. The aim of this review is to summarize the current knowledge about the immune-regulatory mechanisms induced by SLIT against ARDs.

Allergen Immunotherapy in Asthma

Allergen immunotherapy (AIT) is a specific treatment involving the administration of relevant allergens to allergic patients, with subtypes including subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT). In asthma, AIT using the house dust mite (HDM) alleviates clinical symptoms and decreases airway hyper responsiveness and medication dose. In addition, AIT can improve the natural course of asthma. For example, the effects of AIT can be preserved for at least a few years, even after ending treatment. AIT may increase the remission rate of asthma in children and suppress sensitization to new allergens. If AIT is introduced in pollinosis, AIT may prevent the development of asthma. Moreover, AIT can control other allergic diseases complicated by asthma, such as allergic rhinitis, which also improves the control of asthma. The indication of HDM-SCIT for asthma is mild-to-moderate HDM-sensitized allergic asthma in a patient with normal respiratory function. To date, HDM-SLIT is applicable in Japan for allergic rhinitis, not for asthma. However, the effect of SLIT on asthma has been confirmed internationally, and SLIT is available for asthma in Japan if allergic rhinitis is present as a complication.

Sublingual Immunotherapy: How Sublingual Allergen Administration Heals Allergic Diseases; Current Perspective about the Mode of Action

Owing to the successful application of sublingual immunotherapy (SLIT), allergen immunotherapy (AIT) has become one of the leading treatments for allergic diseases. Similar to the case with other AITs, such as subcutaneous and oral immunotherapies, not only the alleviation of allergic symptoms, but also the curing of the diseases can be expected in patients undergoing SLIT. However, how and why such strong efficacy is obtained by SLIT, in which allergens are simply administered under the tongue, is not clearly known. Various potential mechanisms, including the induction of blocking antibodies, T cell tolerance, regulatory B and T cells, CD103^-CD11b⁺ classical dendritic cells, and CD206⁺ macrophages, and the reduction of innate lymphoid cells, mast cells, and basophils, have been suggested. Recently, through a comparative analysis between high- and non-responder patients of SLIT, we have successfully proposed several novel mechanisms. Here, we introduce our recent findings and summarize the current understanding of the mechanisms underlying the strong efficacy of SLIT.

The safety of sublingual immunotherapy, can the rare systemic reactions be prevented?

Introduction: The safety of subcutaneous immunotherapy (SCIT), and particularly the dramatic issue of fatal reactions, has been an obstacle that limited the implementation of a therapy with unique characteristics of action on the causes of allergy. The introduction of sublingual immunotherapy (SLIT) was aimed at solving safety problems while maintaining clinical efficacy.Areas covered: For more than 20 years, SLIT has been based on allergen extracts in drops at low average doses. As evidenced by meta-analyses, the typical adverse events (AE) have consisted of local reactions in the mouth and throat. Unlike the injection route, no correlation was observed between the administered dose and AEs. The development of SLIT products in tablets, based on higher doses than drops, has somewhat changed the concept of SLIT safety. Although large trials, performed to obtain regulatory agency approval, have shown overall high safety, rare anaphylactic reactions have been described.Expert opinion: SLIT is globally safe, and no fatal reactions have ever been reported, but with currently available high biological potency products it is necessary to follow prudential rules, such as the administration of the first dose under medical supervision and the thorough education of patients to avoid taking of higher doses than recommended.

Role of Allergen Immunotherapy in Asthma Treatment and Asthma Development

Allergen immunotherapy may modify the natural course of allergic diseases and induce remission. It includes subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT). For asthma, allergen immunotherapy using house dust mite (HDM) improves clinical symptoms and airway hyperresponsiveness and decreases drug requirements. Furthermore, it has been suggested that allergen immunotherapy also has the following effects: (1) the effect can be maintained for more than a year even if the treatment is terminated, (2) the remission rate of childhood asthma can be increased, (3) new allergen sensitization can be suppressed, and (4) asthma development can be prevented if allergen immunotherapy was performed in the case of pollinosis. Allergen immunotherapy differs from conventional drug therapy, in particular the effect of modifying the natural course of allergic diseases and the effect of controlling complicated allergic diseases such as rhinoconjunctivitis. The general indication for HDM-SCIT in asthma is HDM-sensitized atopic asthma with mild-to-moderate disease and normal respiratory function. HDM allergens should be involved in the pathogenesis of asthma, and a duration of illness of less than 10 years is desirable. HDM-SLIT is available for allergic rhinitis but not for asthma in Japan. However, as the efficacy of SLIT for asthma has been fully proven internationally, SLIT is also applied in asthmatics with complicated allergic rhinitis in Japan.

Use of Sublingual Immunotherapy for Aeroallergens in Children with Asthma

Asthma is a heterogeneous disease that in children is often allergen-driven with a type 2 inflammation. Sublingual immunotherapy represents an important progress in the use of personalized medicine in children with allergic asthma. It is a viable option for house dust mite-driven asthma and in subjects with the asthma associated with allergic rhinitis. The use and indications for isolated asthma caused by other allergens are still controversial owing to heterogeneity of commercially available products and methodological limitations of studies in children. Nevertheless, most studies and meta-analyses found the efficacy of sublingual immunotherapy. Sublingual immunotherapy is safe but cannot be recommended in children with uncontrolled asthma.

Sublingual immunotherapy for asthma

BACKGROUND

Asthma is a common long-term respiratory disease affecting approximately 300 million people worldwide. Approximately half of people with asthma have an important allergic component to their disease, which may provide an opportunity for targeted treatment. Sublingual immunotherapy (SLIT) aims to reduce asthma symptoms by delivering increasing doses of an allergen (e.g. house dust mite, pollen extract) under the tongue to induce immune tolerance. Fifty-two studies were identified and synthesised in the original Cochrane Review in 2015, but questions remained about the safety and efficacy of sublingual immunotherapy for people with asthma.

OBJECTIVES

To assess the efficacy and safety of sublingual immunotherapy compared with placebo or standard care for adults and children with asthma.

SEARCH METHODS

The original searches for trials from the Cochrane Airways Group Specialised Register (CAGR), ClinicalTrials.gov, WHO ICTRP, and reference lists of all primary studies and review articles found trials up to 25 March 2015. The most recent search for trials for the current update was conducted on 29 October 2019.

SELECTION CRITERIA

We included parallel randomised controlled trials, irrespective of blinding or duration, that evaluated sublingual immunotherapy versus placebo or as an add-on to standard asthma management. We included both adults and children with asthma of any severity and with any allergen-sensitisation pattern. We included studies that recruited participants with asthma, rhinitis, or both, providing at least 80% of trial participants had a diagnosis of asthma. We selected outcomes to reflect recommended outcomes for asthma clinical trials and those most important to people with asthma. Primary outcomes were asthma exacerbations requiring a visit to the emergency department (ED) or admission to hospital, validated measures of quality of life, and all-cause serious adverse events (SAEs). Secondary outcomes were asthma symptom scores, exacerbations requiring systemic corticosteroids, response to provocation tests, and dose of inhaled corticosteroids (ICS).

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results for included trials, extracted numerical data, and assessed risk of bias, all of which were cross-checked for accuracy. Any disagreements were resolved by discussion. We analysed dichotomous data as odds ratios (ORs) or risk differences (RDs) using study participants as the unit of analysis; we analysed continuous data as mean differences (MDs) or standardised mean differences (SMDs) using random-effects models. We considered the strength of evidence for all primary and secondary outcomes using the GRADE approach.

MAIN RESULTS

Sixty-six studies met the inclusion criteria for this update, including 52 studies from the original review. Most studies were double-blind and placebo-controlled, varied in duration from one day to three years, and recruited participants with mild or intermittent asthma, often with comorbid allergic rhinitis. Twenty-three studies recruited adults and teenagers; 31 recruited only children; three recruited both; and nine did not specify. The pattern of reporting and results remained largely unchanged from the original review despite 14 further studies and a 50% increase in participants studied (5077 to 7944). Reporting of primary efficacy outcomes to measure the impact of SLIT on asthma exacerbations and quality of life was infrequent, and selective reporting may have had a serious effect on the completeness of the evidence; 16 studies did not contribute any data, and a further six studies could only be included in a post hoc analysis of all adverse events. Allocation procedures were generally not well described; about a quarter of the studies were at high risk of performance or detection bias (or both); and participant attrition was high or unknown in around half of the studies. The primary outcome in most studies did not align with those of interest to the review (mostly asthma or rhinitis symptoms), and only two small studies reported our primary outcome of exacerbations requiring an ED or hospital visit; the pooled estimate from these studies suggests SLIT may reduce exacerbations compared with placebo or usual care, but the evidence is very uncertain (OR 0.35, 95% confidence interval (CI) 0.10 to 1.20; n = 108; very low-certainty evidence). Nine studies reporting quality of life could not be combined in a meta-analysis and, whilst the direction of effect mostly favoured SLIT, the effects were often uncertain and small. SLIT likely does not increase SAEs compared with placebo or usual care, and analysis by risk difference suggests no more than 1 in 100 people taking SLIT will have a serious adverse event (RD -0.0004, 95% CI -0.0072 to 0.0064; participants = 4810; studies = 29; moderate-certainty evidence). Regarding secondary outcomes, asthma symptom and medication scores were mostly measured with non-validated scales, which precluded meaningful meta-analysis or interpretation, but there was a general trend of SLIT benefit over placebo. Changes in ICS use (MD -17.13 µg/d, 95% CI -61.19 to 26.93; low-certainty evidence), exacerbations requiring oral steroids (studies = 2; no events), and bronchial provocation (SMD 0.99, 95% CI 0.17 to 1.82; low-certainty evidence) were not often reported. Results were imprecise and included the possibility of important benefit or little effect and, in some cases, potential harm from SLIT. More people taking SLIT had adverse events of any kind compared with control (OR 1.99, 95% CI 1.49 to 2.67; high-certainty evidence; participants = 4251; studies = 27), but events were usually reported to be transient and mild. Lack of data prevented most of the planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Despite continued study in the field, the evidence for important outcomes such as exacerbations and quality of life remains too limited to draw clinically useful conclusions about the efficacy of SLIT for people with asthma. Trials mostly recruited mixed populations with mild and intermittent asthma and/or rhinitis and focused on non-validated symptom and medication scores. The review findings suggest that SLIT may be a safe option for people with well-controlled mild-to-moderate asthma and rhinitis who are likely to be at low risk of serious harm, but the role of SLIT for people with uncontrolled asthma requires further evaluation.

Sublingual allergen immunotherapy for respiratory allergy: a systematic review

The objective of the systematic review is to provide complete and updated information on efficacy and safety of sublingual immunotherapy (SLIT) formulations for the treatment of allergic respiratory diseases (ARDs). The literature search was conducted on PubMed database, involving double-blind, randomized clinical trials published between January 1992 and 2018, written in English, and performed in humans. The number of articles finally selected for review was 112. Data from the majority of properly controlled clinical trials demonstrate that SLIT is effective not only with short-term use (first year) but also with long-term use (up to the third year of active therapy), for treating ARDs in children and adults. Both continuous and discontinuous schemes of administration showed significant reductions in symptom and medication scores. Moreover, a SLIT-induced disease-modifying effect has been documented mainly with grass pollen extracts, since improvement is maintained during at least 2 years of follow-up after a 3-year treatment period. Additionally, allergen immunotherapy should also be considered a preventive strategy, especially for decreasing bronchial asthma incidence in children and adolescents with allergic rhinitis treated with SLIT. This therapy is also safe, producing only a few mainly local and mild-to-moderate adverse events, and usually self-limited in time. The registration and authorization of allergen SLIT preparations (grasses and house-dust mite tablets) as drugs by regulatory agencies, such as the United States Food and Drug Administration (FDA) and the European Medicines Agency (EMA), has represented a landmark in allergy immunotherapy research. Further long-term studies, specially designed with allergens other than grass pollen or house-dust mites, not only in allergic rhinoconjunctivitis but also on asthmatic subjects, as well as studies comparing different administration schedules and/or routes, are required in order to continue the progress in the modern development of this particularly promising therapy.

Quality-of-life outcomes in patients who underwent subcutaneous immunotherapy and sublingual immunotherapy in a real-world clinical setting

OBJECTIVE

To compare changes in quality of life (QOL) that resulted from sublingual immunotherapy (SLIT) and subcutaneous immunotherapy (SCIT) in a real-world clinical setting.

BACKGROUND

SLIT is established as a viable alternative to SCIT for the treatment of allergic rhinitis. Although comparative trials are increasingly available, few studies have examined QOL outcomes between these two treatments.

METHODS

One hundred and five participants who underwent immunotherapy for airborne allergies were enrolled in this prospective, single-center study. Forty participants completed the Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ) at initiation of therapy, after 6 months, and after 1 year of therapy. Only patients with complete time points were included in the ultimate analysis. Twenty-nine of these participants underwent SCIT and 11 underwent SLIT. The effects of age, sex, and asthma history were also examined.

RESULTS

The participants in both groups demonstrated improvements in QOL regarding allergic rhinoconjunctivitis over the study period. However, the change in the RQLQ score from both baseline to 6 months and baseline to 1 year was only statistically significant in the SCIT group (p = 0.002, 6 months and 1 year). The participants in the SCIT group also demonstrated statistically significant improvement from baseline to 1 year in the specific domains of practical and emotional functioning, nasal symptoms, non-nasal/eye symptoms, and sleep. After 1 year, both SCIT and SLIT demonstrated a minimally important difference from baseline in the overall RQLQ score. Age <35 years in the SCIT group had a significant positive impact on QOL improvement (p = 0.038).

CONCLUSION

Although improvements in QOL were noted in both groups, changes in overall scores and the majority of domains only achieved statistical significance in the SCIT group. A small study population and difficulties adhering to immunotherapy dosing schedules in the SLIT group may be contributing factors.

House dust mite sublingual immunotherapy in allergic rhinitis

Allergen immunotherapy has been shown to be effective in treatment of allergic rhinitis (AR). Sublingual immunotherapy (SLIT) is generally recommended for treating seasonal AR in adults and children; however, questions remain in regard to AR treatment in relation to house dust mite (HDM). Due to heterogeneous formulations, different outcome reporting systems, and the lack of a standardized dose, HDM SLITs have not been standardized in published studies. Nevertheless, studies continuously report positive effects of HDM SLIT in AR, and HDM SLIT remains a treatment option for patients with HDM-induced allergic asthma that frequently co-exists with AR. Therefore, it is likely that HDM SLIT usage will increase. This review will focus on HDM SLIT in AR exclusively.

Allergen immunotherapy for allergic asthma: A systematic review and meta-analysis

BACKGROUND

To inform the development of the European Academy of Allergy and Clinical Immunology's (EAACI) Guidelines on Allergen Immunotherapy (AIT) for allergic asthma, we assessed the evidence on the effectiveness, cost-effectiveness and safety of AIT.

METHODS

We performed a systematic review, which involved searching nine databases. Studies were screened against predefined eligibility criteria and critically appraised using established instruments. Data were synthesized using random-effects meta-analyses.

RESULTS

98 studies satisfied the inclusion criteria. Short-term symptom scores were reduced with a standardized mean difference (SMD) of -1.11 (95% CI -1.66, -0.56). This was robust to a prespecified sensitivity analyses, but there was evidence suggestive of publication bias. Short-term medication scores were reduced SMD -1.21 (95% CI -1.87, -0.54), again with evidence of potential publication bias. There was no reduction in short-term combined medication and symptom scores SMD 0.17 (95% CI -0.23, 0.58), but one study showed a beneficial long-term effect. For secondary outcomes, subcutaneous immunotherapy (SCIT) improved quality of life and decreased allergen-specific airway hyperreactivity (AHR), but this was not the case for sublingual immunotherapy (SLIT). There were no consistent effects on asthma control, exacerbations, lung function, and nonspecific AHR. AIT resulted in a modest increased risk of adverse events (AEs). Although relatively uncommon, systemic AEs were more frequent with SCIT; however no fatalities were reported. The limited evidence on cost-effectiveness was mainly available for sublingual immunotherapy (SLIT) and this suggested that SLIT is likely to be cost-effective.

CONCLUSIONS

AIT can achieve substantial reductions in short-term symptom and medication scores in allergic asthma. It was however associated with a modest increased risk of systemic and local AEs. More data are needed in relation to secondary outcomes, longer-term effectiveness and cost-effectiveness.

Biomarkers for monitoring clinical efficacy of allergen immunotherapy for allergic rhinoconjunctivitis and allergic asthma: an EAACI Position Paper

BACKGROUND

Allergen immunotherapy (AIT) is an effective treatment for allergic rhinoconjunctivitis (AR) with or without asthma. It is important to note that due to the complex interaction between patient, allergy triggers, symptomatology and vaccines used for AIT, some patients do not respond optimally to the treatment. Furthermore, there are no validated or generally accepted candidate biomarkers that are predictive of the clinical response to AIT. Clinical management of patients receiving AIT and efficacy in randomised controlled trials for drug development could be enhanced by predictive biomarkers.

METHOD

The EAACI taskforce reviewed all candidate biomarkers used in clinical trials of AR patients with/without asthma in a literature review. Biomarkers were grouped into seven domains: (i) IgE (total IgE, specific IgE and sIgE/Total IgE ratio), (ii) IgG-subclasses (sIgG1, sIgG4 including SIgE/IgG4 ratio), (iii) Serum inhibitory activity for IgE (IgE-FAB and IgE-BF), (iv) Basophil activation, (v) Cytokines and Chemokines, (vi) Cellular markers (T regulatory cells, B regulatory cells and dendritic cells) and (vii) In vivo biomarkers (including provocation tests?).

RESULTS

All biomarkers were reviewed in the light of their potential advantages as well as their respective drawbacks. Unmet needs and specific recommendations on all seven domains were addressed.

CONCLUSIONS

It is recommended to explore the use of allergen-specific IgG4 as a biomarker for compliance. sIgE/tIgE and IgE-FAB are considered as potential surrogate candidate biomarkers. Cytokine/chemokines and cellular reponses provided insight into the mechanisms of AIT. More studies for confirmation and interpretation of the possible association with the clinical response to AIT are needed.

Applications and mechanisms of immunotherapy in allergic rhinitis and asthma

Clinical and immunologic tolerance are hallmarks of successful allergen immunotherapy (AIT). Clinical benefits such as reduced symptoms, pharmacotherapy intake and improvement of quality of life persist following cessation of treatment. Successful AIT is associated with suppression of allergic inflammatory cells such as mast cells, eosinophils and basophils in target organs. Furthermore, AIT down-regulates type 2 innate lymphoid cells and allergen-specific type 2 T-helper (Th2) cells. The immunologic tolerant state following AIT is associated with the induction of distinct phenotypes of regulatory T-cells (T-regs) including interleukin (IL)-10-, IL-35- and transforming growth factor (TGF)-β- producing T-regs and FoxP3⁺ T-regs. B-cell responses, including the induction of IL-10⁺ regulatory B-cells (B-regs) and the production of IgG4-associated blocking antibodies are also induced following successful AIT. These events are associated with the suppression of antigen-specific Th2 responses and delayed immune deviation in favour of Th1 type responses. Insight into the mechanisms of AIT has allowed identification of novel biomarkers with potential to predict the clinical response to AIT and also novel therapeutic strategies for more effective and safer AIT.

Allergen specific sublingual immunotherapy in children with asthma and allergic rhinitis

BACKGROUND

The incidence of asthma and allergic rhinitis (AR) is significantly increased, especially in younger children. Current treatment for children with asthma and allergic rhinitis include allergen avoidance, standard pharmacotherapy, and immunotherapy. Since standard pharmacotherapy is prescribed for symptoms, immunotherapy at present plays an important role in the treatment of allergic diseases. This article presents insights into the up-to-date understanding of immunotherapy in the treatment of children with allergic rhinitis and asthma.

DATA SOURCES

PubMed articles published from 1990 to 2014 were reviewed using the MeSH terms "asthma", "allergic rhinitis", "children", and "immune therapy". Additional articles were identified by hand searching of the references in the initial search.

RESULTS

Numerous studies have shown that sublingual application of allergen specific immunotherapy (SLIT) is an adequate, safe and efficient substitution to subcutaneous route of allergens administration (SCIT) in the treatment of IgE-mediated respiratory tract allergies in children. According to the literature, better clinical efficacy is connected with the duration of treatment and mono sensitized patients.

CONCLUSIONS

At least 3 years of treatment and stable asthma before the immunotherapy are positive predictors of good clinical efficacy and tolerability of SLIT. SLIT reduces the symptoms of allergic diseases and the use of medicaments, and improves the quality of life of children with the diseases.

Analysis of the quality of life of patients with asthma and allergic rhinitis after immunotherapy

Aim

To assess the quality of life of Polish patients with asthma and/or allergic rhinitis before the implementation and after 30–36 months of immunotherapy.

Material and methods

Two hundred patients have been involved in the study: 101 with allergic asthma and 99 with pollinosis. In order to collect research material, the Polish versions of AQLQ (Asthma Quality of Life) and RQLQ (Rhinoconjunctivitis Quality of Life) questionnaires have been used. The self-administered questionnaires concerned such data as age, sex and the patients’ subjective evaluation of their quality of life.

Results

The average increase in quality of life of patients with asthma was 0.84 and of patients with allergic rhinitis – 1.50. A hypothesis was made that changes of quality of life in each examined group differed significantly. A test for two fractions showed that for patients with asthma it was 7.74 and for patients with allergic rhinitis – 10.38. A statistical analysis showed no such relation in the group of patients with asthma (coefficient of correlation = 0.08) and a slight correlation in the group of patients with allergic rhinitis (coefficient of correlation = 0.20). Applied tests did not show any significant differences, which means that an average increase in quality of life does not depend on sex and age of both examined groups.

Conclusions

On the basis of the research conducted among patients before and after a 3-year period of immunotherapy, the following conclusions have been drawn: 1) immunotherapy significantly improves the objective quality of life in both groups; 2) a slight correlation has been identified between the objective and subjective dimension of quality of life amongst patients with asthma, what contributes to a better quality of life; 3) in both study groups, no significant relationship between gender or age and improvement in quality of life has been noted; 4) immunotherapy, from the point of view of the improvement of quality of life, is a valuable therapeutic tool in patients with atopic bronchial asthma and allergic rhinitis.

Safety profile of sublingual immunotherapy

Sublingual immunotherapy (SLIT) was proposed for clinical practice about 20 years ago with the main aim of improving the safety and avoiding the adverse effects of traditional treatment for allergic airways disease. To date, 32 randomized controlled trials and 6 postmarketing surveys have been published that provide a robust documentation of the safety profile of the treatment.Looking at the randomized trials it emerges that the more frequent adverse event of SLIT is oral itching or swelling, followed by gastrointestinal complaints. These adverse events are invariably described as mild and easily managed by adjusting the dose. Relevant systemic adverse events (asthma, urticaria, angioedema) occur sporadically and, with the exception of oral/gastrointestinal adverse events, the incidence of adverse events seems not to differ between the placebo and active groups. The safety profile of SLIT does not differ between adults and children.The postmarketing surveys consistently show that the incidence of adverse events associated with SLIT is less than 10%, corresponding to less than 1 adverse event per 1000 doses, and is thus quite superior to the safety profile of subcutaneous immunotherapy. Of note, the most recent data show that the rate of adverse events with SLIT is not increased in children below the age of 5 years.

Intrasubject Variability in Total IgE Levels in Patients with Moderate to Severe Persistent Allergic Asthma Over 1 Year

BACKGROUND

Longitudinal variability in serum IgE levels has not been prospectively studied in people with moderate to severe allergic asthma.

OBJECTIVE

We investigated change in serum IgE concentrations over 1 year, and its relationship with lung function, asthma control, asthma pharmacotherapy, allergy season, asthma exacerbations, body mass index, and demographic factors.

METHODS

Seventeen patients with moderate to severe persistent allergic asthma were followed for 1 year. Variability in serum IgE level was explored using a linear mixed regression model treating a change of 10% or more in IgE concentration and combined change of 10% or more and an absolute change of 50 IU/mL as dichotomous variables.

RESULTS

For consecutive visits every 2 months, the mean percent change in serum IgE level was 23 ± 3 (P < .001). Probability of having a greater than 10% change in serum IgE level in a subsequent visit was 69% (95% CI, 58%-78%; P < .001). Variability in IgE level could have affected clinical decisions for anti-IgE treatment (dosing and/or treatment candidacy) in 7 of 17 patients. There were no statistically significant associations of IgE level variability with demographic characteristics and lung function, exacerbations, allergy season, Asthma Control Test scores, peak flow rates, pharmacotherapy, or body mass index.

CONCLUSIONS

Serum IgE concentrations exhibit variability over time among individuals with moderate to severe persistent allergic asthma. The factors that contribute to IgE level variability and the impact of these findings on clinical outcomes deserve further study.

[Seasonality in asthma: Impact and treatments]

The role of seasons should be taken into account in the management of asthma. The environment varies between seasons and it is well documented that asthma is modulated by environment. Viruses cause asthma exacerbations peak, in winter, in adults while the peak is present in September in children. Allergens are probably a less powerful source of asthma exacerbation than viruses but pollen involvement in spring and summer and dust mites in autumn are indisputable. Air pollutants, present in summer during the hottest periods, are also highly involved in asthma exacerbations. Indoor air pollution, in winter, is also implicated in asthma disease. All these environmental factors are synergistic and increase the risk of asthma exacerbation. Therapies should be adapted to each season depending on environmental factors potentially involved in the asthma disease.

Sublingual immunotherapy for asthma

BACKGROUND

Asthma is a common long-term respiratory disease affecting approximately 300 million people worldwide. Approximately half of people with asthma have an important allergic component to their disease, which may provide an opportunity for targeted treatment. Sublingual immunotherapy (SLIT) aims to reduce asthma symptoms by delivering increasing doses of an allergen (e.g. house dust mite, pollen extract) under the tongue to induce immune tolerance. However, it is not clear whether the sublingual delivery route is safe and effective in asthma.

OBJECTIVES

To assess the efficacy and safety of sublingual immunotherapy compared with placebo or standard care for adults and children with asthma.

SEARCH METHODS

We identified trials from the Cochrane Airways Group Specialised Register (CAGR), ClinicalTrials.gov (www.ClinicalTrials.gov), the World Health Organization (WHO) trials portal (www.who.int/ictrp/en/) and reference lists of all primary studies and review articles. The search is up to date as of 25 March 2015.

SELECTION CRITERIA

We included parallel randomised controlled trials (RCTs), irrespective of blinding or duration, that evaluated sublingual immunotherapy versus placebo or as an add-on to standard asthma management. We included both adults and children with asthma of any severity and with any allergen-sensitisation pattern. We included studies that recruited participants with asthma, rhinitis, or both, providing at least 80% of trial participants had a diagnosis of asthma.

DATA COLLECTION AND ANALYSIS

Two review authors independently screened the search results for included trials, extracted numerical data and assessed risk of bias, all of which were cross-checked for accuracy. We resolved disagreements by discussion.We analysed dichotomous data as odds ratios (ORs) or risk differences (RDs) using study participants as the unit of analysis; we analysed continuous data as mean differences (MDs) or standardised mean differences (SMDs) using random-effects models. We rated all outcomes using GRADE (Grades of Recommendation, Assessment, Development and Evaluation) and presented results in the 'Summary of findings' table.

MAIN RESULTS

Fifty-two studies met our inclusion criteria, randomly assigning 5077 participants to comparisons of interest. Most studies were double-blind and placebo-controlled, but studies varied in duration from one day to three years. Most participants had mild or intermittent asthma, often with co-morbid allergic rhinitis. Eighteen studies recruited only adults, 25 recruited only children and several recruited both or did not specify (n = 9).With the exception of adverse events, reporting of outcomes of interest to this review was infrequent, and selective reporting may have had a serious effect on the completeness of the evidence. Allocation procedures generally were not well described, about a quarter of the studies were at high risk of bias for performance or detection bias or both and participant attrition was high or unknown in around half of the studies.One short study reported exacerbations requiring a hospital visit and observed no adverse events. Five studies reported quality of life, but the data were not suitable for meta-analysis. Serious adverse events were infrequent, and analysis using risk differences suggests that no more than 1 in 100 are likely to suffer a serious adverse event as a result of treatment with SLIT (RD 0.0012, 95% confidence interval (CI) -0.0077 to 0.0102; participants = 2560; studies = 22; moderate-quality evidence).Within secondary outcomes, wide but varied reporting of largely unvalidated asthma symptom and medication scores precluded meaningful meta-analysis; a general trend suggested SLIT benefit over placebo, but variation in scales meant that results were difficult to interpret.Changes in inhaled corticosteroid use in micrograms per day (MD 35.10 mcg/d, 95% CI -50.21 to 120.42; low-quality evidence), exacerbations requiring oral steroids (studies = 2; no events) and bronchial provocation (SMD 0.69, 95% CI -0.04 to 1.43; very low-quality evidence) were not often reported. This led to many imprecise estimates with wide confidence intervals that included the possibility of both benefit and harm from SLIT.More people taking SLIT had adverse events of any kind compared with control (OR 1.70, 95% CI 1.21 to 2.38; low-quality evidence; participants = 1755; studies = 19), but events were usually reported to be transient and mild.Lack of data prevented most of the planned subgroup and sensitivity analyses.

AUTHORS' CONCLUSIONS

Lack of data for important outcomes such as exacerbations and quality of life and use of different unvalidated symptom and medication scores have limited our ability to draw a clinically useful conclusion. Further research using validated scales and important outcomes for patients and decision makers is needed so that SLIT can be properly assessed as clinical treatment for asthma. Very few serious adverse events have been reported, but most studies have included patients with intermittent or mild asthma, so we cannot comment on the safety of SLIT for those with moderate or severe asthma. SLIT is associated with increased risk of all adverse events.

Dosing of sublingual immunotherapy for allergic rhinitis: evidence-based review with recommendations

BACKGROUND

Since the mid 1980s, the clinical use of sublingual immunotherapy (SLIT) has dramatically increased. However, 1 of the primary barriers to providing SLIT is lack of a published dosing recommendations. The purpose of this work is to provide a range of effective SLIT dosing based upon a rigorous review of the existing evidence base. An appendix with SLIT dosing recommendations is also included.

METHODS

A comprehensive search of the past 25 years of the medical literature using PubMed was performed for specific antigens. Inclusion criteria for articles included: randomized, placebo-controlled studies of SLIT, studies with clinical allergic rhinitis outcomes, and dosing units available to determine the micrograms per month of major allergen administered. The extracted data was used to compile a range of effective SLIT dosing for individual antigens.

RESULTS

Seventy-five articles met the inclusion criteria, providing a range of effective dosing for some allergens. There was commonly a wide range in doses for particular antigens between the individual studies. For some antigens, there was significant overlap in dosage amount between studies showing efficacy and lack of efficacy. Clinical trials meeting inclusion criteria are not available for many allergens.

CONCLUSION

This study provided a comprehensive review of the published sublingual dosing ranges for specific antigens. The review provided a range of effective sublingual doses for some allergens, whereas for other allergens there was insufficient published data to determine specific doses. Recommendations for SLIT dosing were produced based on the data revealed in the review and expert opinion.

Clinical and cytokine responses to house dust mite sublingual immunotherapy

BACKGROUND

Cytokine responses accompanying sublingual immunotherapy (SLIT) responder phenotypes have not previously been reported.

OBJECTIVE

To investigate clinical and cytokine responses of house dust mite (HDM) sensitive patients with allergic rhinitis receiving HDM SLIT or placebo for 2 years.

METHODS

Sixty adults were randomized to receive SLIT or placebo. Clinical symptoms were measured using the Total 5 Symptom Score (TSS5) and Juniper Rhinitis Quality of Life Questionnaire. HDM specific IgE, IgG, skin prick tests, and HDM-stimulated release of interleukin (IL) 5 and interferon γ (IFN-γ) in peripheral blood mononuclear cells was studied at 0, 6, 12, and 24 months and IL-13, IL-4, and IL-10 at 0 and 24 months.

RESULTS

A total of 32 of 39 SLIT and 16 of 21 placebo patients completed the study. There was significant clinical improvement in both the SLIT and placebo groups. Median T5SS decreased from 14.75 to 5.25 in the SLIT group (P < .001) and 12.7 to 6.0 in the placebo group (P = .003). The median quality-of-life score also decreased in the SLIT group (P < .001) and the placebo group (P < .001). A subgroup analysis of patients found a 60% or greater improvement (on the T5SS and the Juniper Rhinitis Quality of Life Questionnaire) in the good responders group and a 30% to 59% improvement or no improvement in the intermediate responders group. This subgroup analysis also found more good responders in the SLIT group (47%) compared with the placebo group (25%; P = .07). Significant decreases in the IL-5/IFN-γ (P < .001), IL-13/IFN-γ (P < .001), and IL-4/IFN-γ (P = .03) ratios were found in the combined good clinical improvement group at 24 months.

CONCLUSION

A good clinical response (≥60% improvement in both TSS5 and quality of life) is associated with significant decreases in IL-5, IL-13, and IL-4 relative to IFN-γ during 2 years of SLIT therapy for HDMs.

A milestone in house dust-mite-allergen immunotherapy: the new sublingual tablet S-524101 (actair)

Subcutaneous allergen-specific immunotherapy has long been used in the treatment of allergic rhinitis and/or asthma and its efficacy has been confirmed. However, due to the discomfort of injections and the risk of severe adverse reactions, alternative routes of allergen administration have emerged. Delivery of allergens through the mucosal route had been proposed and investigated thoroughly, confirming the sublingual route to be the most efficacious. Later, the efficacy and safety of this route have been documented by numerous controlled trials both for house dust mite (HDM) and pollens. Recently, sublingual orodispersable grass pollen allergen tablets were in use followed by the newly developed HDM allergen tablets with satisfactory clinical results: Moreover, very recently 1 year of HDM tablet treatment was demonstrated to exert its clinical efficacy 1 year after discontinuation of tablet IT. The persistence of efficacy after only 1 year of treatment is a new and promising era. Currently, Sublingual Immunotherapy is the most easily administered and safe treatment option until more immunogenic, less allergenic and more efficient allergen extracts are developed.

Monitoring of occupational and environmental aeroallergens-- EAACI Position Paper. Concerted action of the EAACI IG Occupational Allergy and Aerobiology & Air Pollution

Exposure to high molecular weight sensitizers of biological origin is an important risk factor for the development of asthma and rhinitis. Most of the causal allergens have been defined based on their reactivity with IgE antibodies, and in many cases, the molecular structure and function of the allergens have been established. Significant information on allergen levels that cause sensitization and allergic symptoms for several major environmental and occupational allergens has been reported. Monitoring of high molecular weight allergens and allergen carrier particles is an important part of the management of allergic respiratory diseases and requires standardized allergen assessment methods for occupational and environmental (indoor and outdoor) allergen exposure. The aim of this EAACI task force was to review the essential points for monitoring environmental and occupational allergen exposure including sampling strategies and methods, processing of dust samples, allergen analysis, and quantification. The paper includes a summary of different methods for sampling and allergen quantification, as well as their pros and cons for various exposure settings. Recommendations are being made for different exposure scenarios.

An update on allergen immunotherapy and asthma

PURPOSE OF REVIEW

The aim is to review recent literature up to July 2013 concerning the effect of allergen-specific immunotherapy (AIT) on asthma. AIT, effective in combined allergic rhinitis and asthma, was previously described as a convenient approach able to improve clinical outcomes and reduce bronchial hyperresponsiveness. In addition, long-term and preventive effects on the onset of new sensitizations and progression from allergic rhinitis to asthma have been shown.

RECENT FINDINGS

Recent investigations, mainly based on observational or small open trials, confirmed previous findings, showing improvement in asthma control, symptoms and medication usage and steroid-sparing effects, sometimes inconsistent with changes in lung function. Some meta-analyses support the clinical benefit on adult and paediatric asthma. Only few trials, however, were specifically designed to explore asthma endpoints.

SUMMARY

Clinical studies primarily have focused on AIT, and research on asthma endpoints is scarce; however, the evidence of beneficial effect of AIT for the treatment of adults and children affected by allergic rhinitis with or without asthma suggests that this treatment can favourably affect asthma. In children, sublingual AIT has been more extensively investigated than injective. Confirmatory, adequately powered trials are needed to reinforce the evidence of efficacy for individual AIT products. The main drawback in using injective AIT for asthma is the risk of serious adverse reactions and uncontrolled asthma. The sublingual route is better tolerated and does not appear inferior. As standard controller pharmacotherapy seems unable to affect the natural course of asthma, the potentially disease-modifying effect of AIT represents an appealing perspective that requires further investigation.

Dropouts in sublingual allergen immunotherapy trials - a systematic review

Participant dropouts can reduce the power of allergen immunotherapy clinical trials. Evaluation of the dropout rate and reasons for dropout are important not only in the planning of clinical studies but are also relevant for adherence to immunotherapy in daily clinical practice. A systematic review was carried out in order to establish the overall dropout rate among published double-blind, placebo-controlled randomized clinical trials of sublingual immunotherapy for respiratory allergic diseases. Dropouts were analysed in regards to allergen, formulation, treatment schedule, participant age, study size, number of centres and type of allergic disease. Relative dropout rates in placebo and active groups as well as reasons for dropout were also assessed. A total of 81 studies, comprising 9998 patients, were included. Dropout rates in sublingual immunotherapy controlled studies do not appear to be a major problem with a composite dropout percentage of 14% (95% CI:11.9-16). Furthermore, they are not different for active compared to placebo-treated participants. This lends support to the positive clinical outcomes seen in meta-analyses of these trials.

Efficacy of sublingual immunotherapy for allergic asthma: retrospective meta-analysis of randomized, double-blind and placebo-controlled trials

BACKGROUND

Allergen-specific immunotherapy (SIT) is the only available curative choice with a disease-modifying effect against respiratory allergies. The efficacy of SIT via the sublingual route was demonstrated by a number of clinical trials. This meta-analysis was performed to investigate the clinical efficacy and safety of sublingual-specific immunotherapy (SLIT) for allergic asthma.

METHODS

PubMed, EMBASE and the Cochrane Central Register of Controlled Trials were searched for randomized, double-blind and placebo-controlled (DBPC) trials evaluating the efficacy and safety of SLIT on allergic asthma. Subgroup analyses were performed according to age, type of allergen and duration of SLIT treatment.

RESULTS

Sixteen randomized DBPC trials comprising 794 patients in total met the inclusion criteria. The results suggest that SLIT significantly reduces both symptom [standardized mean difference (SMD), -0.74; P=0.006] and medication scores (SMD, -0.78; P=0.02) compared with placebo. SLIT offers a better clinical response in mite sensitive asthmatics but without confirmed proof from subgroup analyses. Prolonged duration of treatment for more than 12 months brings no additive effects. Improvement in the skin prick test was also observed following immunotherapy. There was no consistent effect on forced expiratory volume in 1 s, serum levels of antigen-specific immunoglobulin G4 and immunoglobulin E in the treated group. The risk of adverse effects was relative risk 2.23 (P=0.01).

CONCLUSIONS

SLIT is safe and clinically effective in reducing symptoms and medication use for allergic asthma. Our subgroup analyses failed to identify a disproportionate benefit of SLIT in any specific group of asthmatics, but some possible trends did emerge.

Guideline on allergen-specific immunotherapy in IgE-mediated allergic diseases: S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Society for Pediatric Allergy and Environmental Medicine (GPA), the Medical Association of German Allergologists (AeDA), the Austrian Society for Allergy and Immunology (ÖGAI), the Swiss Society for Allergy and Immunology (SGAI), the German Society of Dermatology (DDG), the German Society of Oto- Rhino-Laryngology, Head and Neck Surgery (DGHNO-KHC), the German Society of Pediatrics and Adolescent Medicine (DGKJ), the Society for Pediatric Pneumology (GPP), the German Respiratory Society (DGP), the German Association of ENT Surgeons (BV-HNO), the Professional Federation of Paediatricians and Youth Doctors (BVKJ), the Federal Association of Pulmonologists (BDP) and the German Dermatologists Association (BVDD)

The present guideline (S2k) on allergen-specific immunotherapy (AIT) was established by the German, Austrian and Swiss professional associations for allergy in consensus with the scientific specialist societies and professional associations in the fields of otolaryngology, dermatology and venereology, pediatric and adolescent medicine, pneumology as well as a German patient organization (German Allergy and Asthma Association; Deutscher Allergie- und Asthmabund, DAAB) according to the criteria of the Association of the Scientific Medical Societies in Germany (Arbeitsgemeinschaft der Wissenschaftlichen Medizinischen Fachgesellschaften, AWMF). AIT is a therapy with disease-modifying effects. By administering allergen extracts, specific blocking antibodies, toler-ance-inducing cells and mediators are activated. These prevent further exacerbation of the allergen-triggered immune response, block the specific immune response and attenuate the inflammatory response in tissue. Products for SCIT or SLIT cannot be compared at present due to their heterogeneous composition, nor can allergen concentrations given by different manufacturers be compared meaningfully due to the varying methods used to measure their active ingredients. Non-modified allergens are used for SCIT in the form of aqueous or physically adsorbed (depot) extracts, as well as chemically modified allergens (allergoids) as depot extracts. Allergen extracts for SLIT are used in the form of aqueous solutions or tablets. The clinical efficacy of AIT is measured using various scores as primary and secondary study endpoints. The EMA stipulates combined symptom and medication scores as primary endpoint. A harmonization of clinical endpoints, e. g., by using the combined symptom and medication scores (CSMS) recommended by the EAACI, is desirable in the future in order to permit the comparison of results from different studies. The current CONSORT recommendations from the ARIA/GA2LEN group specify standards for the evaluation, presentation and publication of study results. According to the Therapy allergen ordinance (TAV), preparations containing common allergen sources (pollen from grasses, birch, alder, hazel, house dust mites, as well as bee and wasp venom) need a marketing authorization in Germany. During the marketing authorization process, these preparations are examined regarding quality, safety and efficacy. In the opinion of the authors, authorized allergen preparations with documented efficacy and safety, or preparations tradeable under the TAV for which efficacy and safety have already been documented in clinical trials meeting WAO or EMA standards, should be preferentially used. Individual formulations (NPP) enable the prescription of rare allergen sources (e.g., pollen from ash, mugwort or ambrosia, mold Alternaria, animal allergens) for specific immunotherapy. Mixing these allergens with TAV allergens is not permitted. Allergic rhinitis and its associated co-morbidities (e. g., bronchial asthma) generate substantial direct and indirect costs. Treatment options, in particular AIT, are therefore evaluated using cost-benefit and cost-effectiveness analyses. From a long-term perspective, AIT is considered to be significantly more cost effective in allergic rhinitis and allergic asthma than pharmacotherapy, but is heavily dependent on patient compliance. Meta-analyses provide unequivocal evidence of the efficacy of SCIT and SLIT for certain allergen sources and age groups. Data from controlled studies differ in terms of scope, quality and dosing regimens and require product-specific evaluation. Therefore, evaluating individual preparations according to clearly defined criteria is recommended. A broad transfer of the efficacy of certain preparations to all preparations administered in the same way is not endorsed. The website of the German Society for Allergology and Clinical Immunology (www.dgaki.de/leitlinien/s2k-leitlinie-sit; DGAKI: Deutsche Gesellschaft für Allergologie und klinische Immunologie) provides tables with specific information on available products for AIT in Germany, Switzerland and Austria. The tables contain the number of clinical studies per product in adults and children, the year of market authorization, underlying scoring systems, number of randomized and analyzed subjects and the method of evaluation (ITT, FAS, PP), separately given for grass pollen, birch pollen and house dust mite allergens, and the status of approval for the conduct of clinical studies with these products. Strong evidence of the efficacy of SCIT in pollen allergy-induced allergic rhinoconjunctivitis in adulthood is well-documented in numerous trials and, in childhood and adolescence, in a few trials. Efficacy in house dust mite allergy is documented by a number of controlled trials in adults and few controlled trials in children. Only a few controlled trials, independent of age, are available for mold allergy (in particular Alternaria). With regard to animal dander allergies (primarily to cat allergens), only small studies, some with methodological deficiencies are available. Only a moderate and inconsistent therapeutic effect in atopic dermatitis has been observed in the quite heterogeneous studies conducted to date. SCIT has been well investigated for individual preparations in controlled bronchial asthma as defined by the Global Initiative for Asthma (GINA) 2007 and intermittent and mild persistent asthma (GINA 2005) and it is recommended as a treatment option, in addition to allergen avoidance and pharmacotherapy, provided there is a clear causal link between respiratory symptoms and the relevant allergen. The efficacy of SLIT in grass pollen-induced allergic rhinoconjunctivitis is extensively documented in adults and children, whilst its efficacy in tree pollen allergy has only been shown in adults. New controlled trials (some with high patient numbers) on house dust mite allergy provide evidence of efficacy of SLIT in adults. Compared with allergic rhinoconjunctivitis, there are only few studies on the efficacy of SLIT in allergic asthma. In this context, newer studies show an efficacy for SLIT on asthma symptoms in the subgroup of grass pollen allergic children, adolescents and adults with asthma and efficacy in primary house dust mite allergy-induced asthma in adolescents aged from 14 years and in adults. Aspects of secondary prevention, in particular the reduction of new sensitizations and reduced asthma risk, are important rationales for choosing to initiate treatment early in childhood and adolescence. In this context, those products for which the appropriate effects have been demonstrated should be considered. SCIT or SLIT with pollen or mite allergens can be performed in patients with allergic rhinoconjunctivitis using allergen extracts that have been proven to be effective in at least one double-blind placebo-controlled (DBPC) study. At present, clinical trials are underway for the indication in asthma due to house dust mite allergy, some of the results of which have already been published, whilst others are still awaited (see the DGAKI table "Approved/potentially completed studies" via www.dgaki.de/Leitlinien/s2k-Leitlinie-sit (according to www.clinicaltrialsregister.eu)). When establishing the indication for AIT, factors that favour clinical efficacy should be taken into consideration. Differences between SCIT and SLIT are to be considered primarily in terms of contraindications. In individual cases, AIT may be justifiably indicated despite the presence of contraindications. SCIT injections and the initiation of SLIT are performed by a physician experienced in this type of treatment and who is able to administer emergency treatment in the case of an allergic reaction. Patients must be fully informed about the procedure and risks of possible adverse events, and the details of this process must be documented (see "Treatment information sheet"; available as a handout via www.dgaki.de/Leitlinien/s2k-Leitlinie-sit). Treatment should be performed according to the manufacturer's product information leaflet. In cases where AIT is to be performed or continued by a different physician to the one who established the indication, close cooperation is required in order to ensure that treatment is implemented consistently and at low risk. In general, it is recommended that SCIT and SLIT should only be performed using preparations for which adequate proof of efficacy is available from clinical trials. Treatment adherence among AIT patients is lower than assumed by physicians, irrespective of the form of administration. Clearly, adherence is of vital importance for treatment success. Improving AIT adherence is one of the most important future goals, in order to ensure efficacy of the therapy. Severe, potentially life-threatening systemic reactions during SCIT are possible, but - providing all safety measures are adhered to - these events are very rare. Most adverse events are mild to moderate and can be treated well. Dose-dependent adverse local reactions occur frequently in the mouth and throat in SLIT. Systemic reactions have been described in SLIT, but are seen far less often than with SCIT. In terms of anaphylaxis and other severe systemic reactions, SLIT has a better safety profile than SCIT. The risk and effects of adverse systemic reactions in the setting of AIT can be effectively reduced by training of personnel, adhering to safety standards and prompt use of emergency measures, including early administration of i. m. epinephrine. Details on the acute management of anaphylactic reactions can be found in the current S2 guideline on anaphylaxis issued by the AWMF (S2-AWMF-LL Registry Number 061-025). AIT is undergoing some innovative developments in many areas (e. g., allergen characterization, new administration routes, adjuvants, faster and safer dose escalation protocols), some of which are already being investigated in clinical trials. Cite this as Pfaar O, Bachert C, Bufe A, Buhl R, Ebner C, Eng P, Friedrichs F, Fuchs T, Hamelmann E, Hartwig-Bade D, Hering T, Huttegger I, Jung K, Klimek L, Kopp MV, Merk H, Rabe U, Saloga J, Schmid-Grendelmeier P, Schuster A, Schwerk N, Sitter H, Umpfenbach U, Wedi B, Wöhrl S, Worm M, Kleine-Tebbe J. Guideline on allergen-specific immunotherapy in IgE-mediated allergic diseases - S2k Guideline of the German Society for Allergology and Clinical Immunology (DGAKI), the Society for Pediatric Allergy and Environmental Medicine (GPA), the Medical Association of German Allergologists (AeDA), the Austrian Society for Allergy and Immunology (ÖGAI), the Swiss Society for Allergy and Immunology (SGAI), the German Society of Dermatology (DDG), the German Society of Oto-Rhino-Laryngology, Head and Neck Surgery (DGHNO-KHC), the German Society of Pediatrics and Adolescent Medicine (DGKJ), the Society for Pediatric Pneumology (GPP), the German Respiratory Society (DGP), the German Association of ENT Surgeons (BV-HNO), the Professional Federation of Paediatricians and Youth Doctors (BVKJ), the Federal Association of Pulmonologists (BDP) and the German Dermatologists Association (BVDD). Allergo J Int 2014;23:282-319.

An evidence-based analysis of house dust mite allergen immunotherapy: a call for more rigorous clinical studies

BACKGROUND

According to meta-analyses and reviews, subcutaneous allergen immunotherapy (SCIT) and sublingual allergen immunotherapy (SLIT) are beneficial in patients with allergic rhinitis (AR) and allergic asthma (AA) induced by house dust mites (HDMs). However, the reported effect sizes have varied greatly from one study to another.

OBJECTIVE

We sought to perform an evidence-based medicine assessment of commercially available SCIT and SLIT formulations in patients with HDM-induced AA and HDM-induced AR.

METHODS

We searched for double-blind, placebo-controlled randomized clinical trials and analyzed study designs, doses, regimens, patient-reported outcomes, safety reporting, and compliance.

RESULTS

Forty-four studies met our inclusion criteria. Some studies tested both SLIT and SCIT or scored both AA and AR outcomes; therefore we reviewed 35 treatment arms in patients with AA (20 for SCIT and 15 for SLIT) and 23 treatment arms in patients with AR (7 for SCIT and 16 for SLIT). The treatment duration ranged from 6 weeks to 3 years. For SCIT, the dose of Der p 1 major allergen (when reported) ranged from 7 to 30 μg for maintenance doses and 60 to 420 μg for cumulative doses. For SLIT, the doses of Der p 1 (when reported) were 0.8 to 70 μg for maintenance doses and 60 to 23,695 μg for cumulative doses. Safety data were often absent or poorly reported. A statistically significant active versus placebo symptom score was observed more frequently for SCIT than for SLIT.

CONCLUSION

There is no consensus on basic treatment parameters (eg, dose and duration) in HDM SCIT and SLIT. There is an urgent need for rigorous, long-term, double-blind, placebo-controlled randomized clinical trials with an efficacy criterion that reflects the particular features of HDM-induced allergic disease.

Allergen immunotherapy for house dust mite: clinical efficacy and immunological mechanisms in allergic rhinitis and asthma

INTRODUCTION

There is an increasing prevalence of atopic diseases such as allergic rhinitis and asthma with house dust mite (HDM) being the common allergen that is highly associated with allergic rhinitis and asthma. Allergen avoidance and pharmacotherapy are part of treatment but it has proved difficult to change the course of HDM-related allergic diseases. Allergen immunotherapy (AIT) has been in use for the past century and has been shown to be effective in the treatment of allergic respiratory disease.

AREAS COVERED

This review exclusively focuses on HDM-AIT and discusses the differences in clinical efficacy and safety, long-term effect after discontinuation and immunological changes observed in both HDM-subcutaneous immunotherapy (SCIT) and HDM-sublingual immunotherapy (SLIT) in the treatment of allergic rhinitis and asthma in both pediatric and adult populations.

EXPERT OPINION

The majority of studies involved small numbers of patients, variable doses of major allergens and are of variable quality. There is good evidence for HDM-SCIT efficacy and its long-term effect in adults and children, whereas at the present time, evidence for HDM-SLIT is unconvincing, particularly in children. In carefully selected patients, HDM-SCIT is effective and safe. More definitive trials are needed before HDM-SLIT can be recommended in routine practice for rhinitis and/or asthma.

Absence of IgE neosensitization in house dust mite allergic patients following sublingual immunotherapy

BACKGROUND

The impact of sublingual immunotherapy (SLIT) on IgE neosensitization remains to be evaluated in large cohorts of patients.

OBJECTIVES

The aim of this study was to assess the dynamics of antibody responses induced in patients with allergic rhinitis during a 12-month treatment with sublingual tablets of house dust mites (HDM) allergen extracts.

METHODS

Antibody responses were assessed in relationship with neosensitization and clinical benefit in sera from 509 European house dust mite-allergic patients before and after 1 year of daily sublingual immunotherapy, using tablets containing Dermatophagoides pteronyssinus plus D farinae extracts or placebo (ClinicalTrials.gov NCT00674700). Patients were followed for one additional year after treatment cessation. IgE and IgG4 antibodies specific for mite extracts or purified group 1, 2 and 10 allergens were assessed using Immulite, Immunocap and ISAC assays.

RESULTS

After 1 year of SLIT, mite-specific IgE and IgG4 titres increased by 1.5-fold and fourfold, respectively, in the active, but not in the placebo group. A strong IgG4 induction occurred in a subgroup (i.e. 10-15%) of "immunoreactive" patients, without any correlation with improvement in the average adjusted symptom score. Pre-existing IgE levels to purified mite allergens were not impacted during immunotherapy, and no de novo IgE responses to group 1, 2, 10 allergens were induced in patients who were unsensitized prior to immunotherapy. Similarly, no IgE neosensitization to wheat germ or yeast components used in the mite culture medium was observed.

CONCLUSIONS AND CLINICAL RELEVANCE

We document in a cohort of 509 patients followed over a 2-year period that SLIT does not induce any IgE neosensitization to allergens contained in the vaccine, such as groups 1, 2 as well as the food-related group 10 allergen. This observation further corroborates the safer safety profile of SLIT over SCIT.

Efficacy and safety of sublingual immunotherapy in Asian children

OBJECTIVE

Sublingual immunotherapy is currently accepted as a suitable alternative to subcutaneous immunotherapy because of its easy and painless administration and improved safety. Many clinical trials have demonstrated that sublingual immunotherapy is an effective and safe treatment for pollen or mite allergic rhinitis. However, there have been very few studies overall on children with allergic rhinitis who are sensitized to house-dust mites in Asia. The purpose of the present study was to investigate the efficacy and safety of sublingual immunotherapy in children with allergic rhinitis to house-dust mites.

METHODS

A total of 112 patients under the age of 15 who had allergic rhinitis to Dermatophagoides pteronyssinus and Dermatophagoides farinae were included. All patients were treated with sublingual immunotherapy (Staloral(®)). Symptom scores and quality of life were evaluated by questionnaires until one year after sublingual immunotherapy. The medication score was assessed monthly using a diary medication card and serologic tests were evaluated before and 6 and 12 months after treatment. Adverse effects and compliance were also investigated.

RESULTS

All nasal and non-nasal symptoms and quality of life were significantly improved after treatment. The total medication score was decreased significantly after sublingual immunotherapy. There was no significant change in serologic tests. Some minor adverse effects were reported, however there were no systemic reactions. The drop-out rate was 21%.

CONCLUSIONS

Sublingual immunotherapy is a valuable therapy for the treatment of allergic rhinitis in Asian children sensitized to house-dust mites.

Novel routes for allergen immunotherapy: safety, efficacy and mode of action

Allergen immunotherapy is the only curative treatment of IgE-mediated type I respiratory allergies. Subcutaneous immunotherapy (SCIT) is used as a reference therapy and has transformed allergic treatments; it improves symptoms (asthma and rhinitis) as well as the quality of life of patients. SCIT requires repetitive administration and carries the risk of severe systemic adverse effects, including anaphylaxis. Sublingual immunotherapy is now a valid noninvasive alternative to SCIT, as a safe and efficacious treatment for respiratory allergies. In this article, we compare various routes of allergen immunotherapy, including SCIT and sublingual immunotherapy, as well as more exploratory routes currently under investigation (i.e., intralymphatic, epicutaneous, intranasal and oral). We discuss their respective advantages, as well as their foreseen modes of action.

Requirements for acquiring a high-quality house dust mite extract for allergen immunotherapy

The house dust mite is a major cause of respiratory allergy worldwide. The management of mite allergy is based on avoidance measures, drug treatment, and allergen immunotherapy, but only allergen immunotherapy is able to modify the natural history of the disease. Injectable subcutaneous immunotherapy was introduced a century ago, while sublingual immunotherapy was proposed in the 1980s and emerged in the ensuing years as an effective and safe option to subcutaneous immunotherapy. However, the quality of the extracts to be used in allergen immunotherapy is crucial for the success of treatment. The mite extract for sublingual immunotherapy known as Staloral 300 was developed to offer optimal characteristics concerning the mite culture medium, standardization, and allergen dose. Double-blind, placebo-controlled trials with Staloral 300 have provided a substantial part of the clinical evidence analyzed in a meta-analysis of the efficacy of allergen immunotherapy in mite-induced rhinitis and asthma. Safety and tolerability are very good, mild local reactions in the mouth being the most common side effect. This makes it feasible to carry out sublingual immunotherapy for the 3–5-year duration needed to achieve long-lasting tolerance to the specific allergen. The performance of Staloral 300 may provide optimal conditions for an effective and safe sublingual immunotherapy in patients with mite-induced respiratory allergy.

Clinically significant variability of serum IgE concentrations in patients with severe asthma

OBJECTIVE

To determine the magnitude of immunoglobulin E (IgE) variability in a cohort of patients with severe asthma considered for omalizumab therapy.

METHODS

Retrospective chart review identified 65 patients with two or more IgE determinations out of the 124 patients referred to the Cleveland Clinic Respiratory Institute for treatment with omalizumab from 2003 to 2011. Patients with conditions known to affect IgE concentrations were excluded. Demographic data, pulmonary function testing, medications, smoking status, and atopy were recorded. The range of variability and percent variability in relation to baseline serum IgE were calculated.

RESULTS

The median difference of serum IgE between the minimal and maximal values was 94.9 IU/ml (IQR 26.3-324.1 IU/ml). Percent variability from minimum value had a median of 75.5% (IQR 23.3-152.6%). There was no correlation between age, body mass index, lung function, and IgE variability. Greater variability was associated with female gender (p = .06). There was no association with peripheral eosinophilia, systemic corticosteroid use, and leukotriene modifier use at presentation. The observed variability would have affected omalizumab dosing in 20 out of 42 patients. Six patients who may have qualified at different time points would not have been deemed candidates based on an IgE concentration <30 IU/ml or >700 IU/ml.

CONCLUSION

Serum IgE concentration may have clinically significant variability over time, affecting candidacy and dosing of omalizumab. Our findings imply that repeating serum IgE determinations merits consideration for patients whose initial concentrations are <30 or >700 IU/ml. Prospective studies are warranted to delineate the factors that contribute to IgE variability.

Induction of tolerance via the sublingual route: mechanisms and applications

The clinical efficacy of sublingual immunotherapy (SLIT) with natural allergen extracts has been established in IgE-dependent respiratory allergies to grass or tree pollens, as well as house dust mites. Sublingual vaccines have an excellent safety record, documented with approximately 2 billion doses administered, as of today, in humans. The oral immune system comprises various antigen-presenting cells, including Langerhans cells, as well as myeloid and plasmacytoid dendritic cells (DCs) with a distinct localisation in the mucosa, along the lamina propria and in subepithelial tissues, respectively. In the absence of danger signals, all these DC subsets are tolerogenic in that they support the differentiation of Th1- and IL10-producing regulatory CD4(+) T cells. Oral tissues contain limited numbers of mast cells and eosinophils, mostly located in submucosal areas, thereby explaining the good safety profile of SLIT. Resident oral Th1, Th2, and Th17 CD4(+) T cells are located along the lamina propria, likely representing a defence mechanism against infectious pathogens. Second-generation sublingual vaccines are being developed, based upon recombinant allergens expressed in a native conformation, possibly formulated with Th1/T reg adjuvants and/or mucoadhesive particulate vector systems specifically designed to target oral dendritic cells.

Effect of one-year subcutaneous and sublingual immunotherapy on clinical and laboratory parameters in children with rhinitis and asthma: a randomized, placebo-controlled, double-blind, double-dummy study

BACKGROUND

It has been reported that both sublingual (SLIT) and subcutaneous (SCIT) allergen-specific immunotherapy have clinical efficacy, yet there are rather few comparative placebo studies of children. We aimed to investigate the clinical and immunological efficacy of mite-specific SLIT and SCIT versus a placebo in rhinitis and asthma in children.

METHODS

The outcomes of this 1-year, randomized, placebo-controlled, double-blind, double-dummy study were symptom and medication scores, visual analog scores (VAS), titrated skin prick tests, nasal and bronchial allergen provocation doses, serum house dust mite-specific immunglobulin E (HDM-sIgE), sIgG4, IL-10 and IFN-γ levels.

RESULTS

Clinical and laboratory parameters were evaluated in 30 patients. SCIT significantly diminished symptom and medication scores for rhinitis and asthma (p = 0.03 and p = 0.05 for rhinitis; p = 0.01 and p = 0.05 for asthma) and VAS. SLIT also reduced VAS, symptoms associated with rhinitis and asthma as well as medication usage for rhinitis, but this reduction was not significant when compared with the placebo. Skin reactivitiy to HDM and HDM-sIgE levels was reduced significantly in both immunotherapy groups. Serum IL-10 levels and nasal provocative doses increased significantly with both SCIT and SLIT. Nasal eosinophil increments after nasal challenge decreased with two treatment modes, but bronchial provocative doses and sputum eosinophil increments after bronchial challenge were reduced only with SCIT. In both treatment arms, there was no change in IFN-γ levels. Serum sIgG4 levels increased significantly only in the SCIT group.

CONCLUSION

Based on the limited number of patients at the end of the 1-year immunotherapy, the clinical efficacy of SCIT on rhinitis and asthma symptoms was more evident when compared with the placebo.

Evaluation of therapeutic sublingual vaccines in a murine model of chronic house dust mite allergic airway inflammation

BACKGROUND

Second generation therapeutic vaccines based upon recombinant allergens or natural extracts, potentially formulated in vector systems or adjuvants, are being developed. To this aim, preclinical studies in relevant animal models are needed to select proper allergens, formulations and administration schemes.

OBJECTIVE

To develop a chronic house dust mite (HDM) allergy model to evaluate sublingual therapeutic vaccine candidates.

METHODS

The BABL/c mice that were used were sensitized with Dermatophagoides pteronyssinus (Dpte) and Dermatophagoides farinae (Dfar) mite extracts by intraperitoneal injections followed by aerosol exposures. Animals subsequently underwent sublingual immunotherapy (SLIT) with either Dpte, Dfar or Dpte/Dfar extracts, twice a week for 8 weeks. SLIT efficacy was assessed by whole body plethysmography, lung histology and broncho-alveolar lavages cell counts. Specific T cell and antibody responses to major and minor HDM allergens were monitored in tissues and serum/saliva, respectively.

RESULTS

Mice sensitized to Dpte and Dfar allergens exhibited strong airway hyperresponsiveness (AHR) and lung inflammatory infiltrates including eosinophils. Sensitized animals mounted Th2-biased cellular and humoral responses specific for group 1 and 2 major allergens, as well as group 5, 7 and 10 minor allergens. This phenotype was sustained for at least 2 months, allowing the evaluation of immunotherapeutic protocols with HDM extracts-based vaccines. In this model, SLIT decreased AHR and Th2 responses and induced HDM-specific IgAs in saliva. The Dpte/Dfar mix proved the most efficacious when compared to Dpte or Dfar extracts alone.

CONCLUSIONS AND CLINICAL RELEVANCE

The efficacy of a sublingual vaccine based on a Dpte/Dfar allergen extract mix was demonstrated in a well standardized murine model of chronic allergic airway inflammation based on clinically relevant mite allergens. The latter will be used as a benchmark for evaluation of future vaccines, including recombinant allergens. This HDM allergic airway inflammation animal model is a useful tool to design and select candidate vaccines to be tested in humans.

Sublingual immunotherapy for allergic respiratory diseases: efficacy and safety

Subcutaneous immunotherapy (SCIT) is effective and safe when properly prescribed and administered. However, a certain risk of severe side effects exists, even when the reaction is managed correctly. These potential adverse effects stimulated the search for new administration routes (nasal, bronchial, oral, sublingual), which were expected to be safer. Not all of these alternative routes provided an improved benefit-safety profile compared with SCIT. The sublingual route (SLIT) seemed to be a good candidate for the clinical practice because of its satisfactory safety profile and is now considered an acceptable alternative to SCIT in adults and children.