Update on house dust mite immunotherapy: are more studies needed?

[Pitfalls in the diagnosis of house dust mite allergy]

House dust mite (HDM) is the most significant indoor allergen, responsible for not only many cases of rhinoconjunctivitis but also for many cases of bronchial asthma, rendering it of considerable socioeconomic relevance. Besides symptomatic treatment and avoidance measures, allergen immunotherapy (AIT) is crucial, as the only causal, disease-modifying therapeutic approach. However, high diagnostic certainty is essential for initiating AIT. The challenge in making a correct diagnosis lies in interpreting the demonstrated HDM sensitization regarding its clinical relevance (clinically silent sensitization vs. allergy). While the risk of allergy increases with the level of IgE titers against HDM extract, Der p 1, or Der p 2, as well as with the breadth of the molecular sensitization profile against HDM components (Der p 1, Der p 2, Der p 23), no threshold can be defined for the presence of allergy, nor can sensitization to a specific component be confidently considered allergy inducing. It should be noted that at least in Southern Bavaria, the prevalence of Der p 23 sensitization is too low to be considered a major allergen, and Der p 23 is not able to molecularly differentiate all HDM sensitizations when added to the two major allergens Der p 1 and Der p 2. Evidently, HDM possesses a diverse profile of allergens, with some relevant ones possibly yet to be described. Unfortunately, patient history does not provide a sufficient assessment of the clinical relevance of a demonstrated HDM sensitization, necessitating allergen provocation testing before initiating AIT with HDM, despite the relatively large effort involved.

Real-world evidence of subcutaneous allergoid immunotherapy in house dust mite-induced allergic rhinitis and asthma

BACKGROUND

The objective of this study was to analyze the effectiveness of allergen immunotherapy (AIT) with an allergoid in the treatment of house dust mites (HDM)-induced allergic rhinitis and/or asthma based on recent real-life data. The outcomes were measured using asthma incidence and consumption of corresponding medications as the indicator of persisting symptoms.

METHODS

In this retrospective cohort analysis of a German longitudinal prescription database, patients who received at least two relevant mite AIT prescriptions in two different successive seasonal cycles were compared with non-AIT patients who received at least three symptomatic allergic rhinitis (AR) prescriptions in successive mite seasons. Study endpoints included AR progression, asthma progression, asthma occurrence, and therapy adherence. We used multivariate regression analyses to estimate the effects of AIT, adjusting for relevant variables.

RESULTS

This study included 2350 patients receiving a mite allergoid and 64 740 control patients. After up to 6 years of follow-up, patients treated with mite allergoid required significantly fewer AR and asthma prescriptions (59.7% vs 10.8%) than the control group, and the probability of asthma development was significantly lower. The adherence of patients receiving allergoid was 63.8% at the end of the second year and 38.6% at the end of the third year.

CONCLUSIONS

This real-world evidence confirms the good efficacy of subcutaneous AIT with HDM mite allergoid in the treatment of allergic rhinitis and/or asthma. Up to 6 years of follow-up revealed significant effects in allergic rhinitis by measuring the number of AR medications and demonstrating significant reductions in asthma medications.

Clinical Practice of Allergen Immunotherapy for Allergic Rhinoconjunctivitis and Asthma: An Expert Panel Report

Allergen immunotherapy (AIT) reduces symptoms and medication use associated with allergic rhinitis with or without conjunctivitis and allergic asthma. Although several AIT guidelines exist, there remain unanswered questions about AIT that are relevant to everyday practice. Our objective was to prepare an evidence-based overview addressing the practical aspects of AIT in clinical practice based on published evidence and the experience of international experts in the field. Topics covered include interpretation and translation of clinical trial data into everyday clinical practice (eg, allergen doses and treatment duration), assessment of risk and treatment of local and systemic allergic reactions, recommendations for improvement of AIT guidelines, and identification of appropriate data for seeking regulatory approval, to name a few. Many informational gaps in AIT practice need further evaluation as products and practices evolve.

Sublingual Immunotherapy Tablets Relieve Symptoms in Adults with Allergic Rhinitis: A Meta-analysis of Randomized Clinical Trials

Background:

Sublingual immunotherapy (SLIT) has been proven to be effective against house dust mite-induced allergic rhinitis. However, the efficacy in adults with allergic rhinitis has never been reported on SLIT tablets. The current meta-analysis aimed to illustrate the differentiated efficacy of SLIT tablets on allergic rhinitis.

Methods:

Our systematic review and meta-analysis were performed on allergic rhinitis patients and aimed to summarize those randomized controlled studies (RCTs). PubMed, EMBASE, Cochrane library, and MEDLINE were screened for associated articles. We included RCTs on allergic rhinitis patients undergoing SLIT therapy and reporting outcomes on symptom relief and serum-specific IgE levels. The effect of SLIT tablets on the Rhinitis Quality Life Questionnaire Score (RQLQ), Rhinitis Total Symptom Score (RTSS), and serum-specific IgE levels was evaluated using RevMan 5.3.

Results:

Seven studies were included, with 2723 patients identified. All of the studies were RCT. The included seven studies were all conducted on adults. Among the included seven articles, five researches administered patients with SLIT tablets and were eligible for meta-analysis of RTSS, consisting of 1490 patients. Overall, RTSS was significantly reduced in the SLIT tablet group compared with that in the placebo group (standard mean difference = −0.33, 95% confidence interval [−0.54, −0.13], P < 0.01). There was no significant difference in specific IgE levels between SLIT and placebo patients.

Conclusions:

SLIT tablets effectively relieve rhinitis symptoms in adults with allergic rhinitis. Nevertheless, the current evidence may be limited due to sample size and the heterogeneity between studies. Large sample size and multiple center RCTs on the efficacy of different formulations of SLIT drugs are still needed to provide further evidence and a more precise recommendation.

Sublingual immunotherapy for pediatric allergic conjunctivitis: a meta-analysis of randomized controlled trials

BACKGROUND

Allergic conjunctivitis (AC) is a common chronic condition, especially in children. Ocular symptoms are often overlooked during treatment of allergic rhinoconjunctivitis (ARC). Pediatric ARC can be effectively treated using sublingual immunotherapy (SLIT), which is a guideline-recommended safe treatment approach. However, the therapeutic efficacy of SLIT in terms of ameliorating eye symptoms has not been effectively evaluated.

METHODS

We performed a meta-analysis of randomized controlled trials (RCTs) evaluating the use of SLIT for infants, children, and adolescents (aged from 3 to 18 years) with AC or ARC. We searched the Cochrane Library database, EMBASE, and Medline from November 1990 to 2017 to find papers dealing with the effects of SLIT on pediatric AC or ARC. We used standardized mean differences (SMDs) to assess therapeutic effects, employing a random effects model. Subgroup and sensitivity analyses were also conducted. The I² metric was used to evaluate heterogeneity.

RESULTS

In total, 13 clinical RCTs were included in our meta-analysis. SLIT reduced ocular symptoms to a level below that of controls (SMD = -0.21; 95% confidence interval [CI], -0.41 to -0.01; p = 0.04; I² = 55%). Notably, on subgroup analysis, SLIT clearly reduced pollen-induced pediatric AC (SMD = -0.36; 95% CI, -0.53 to -0.19; p < 0.0001; I² = 25%) but not mite-induced AC (SMD = 0.20; 95% CI, -0.20 to 0.60; p = 0.34; I² = 46%).

CONCLUSION

SLIT relieved ocular symptoms in children with ARC or AC. To confirm these results, future meta-analyses should evaluate high-quality, large-scale population-based trials.

Sublingual house dust mite immunotherapy has no impact on decrease of circulating erythrocytes upon airway allergen challenge in allergic rhinitis

House dust mite (HDM) allergy is a predominant cause for perennial allergic rhinitis (AR) in Europe. We recently reported that circulating erythrocyte numbers decrease after airway allergen challenge in a murine asthma model and in grass-pollen sensitized AR subjects. Consequently, we aimed to evaluate these findings in HDM sensitized AR subjects and the influence of preceding allergen immunotherapy. Seventy-seven (age 26.8 ± 7.3 years; 54.5% female) HDM-allergic rhinitis subjects previously enrolled in a randomized, monocentric sublingual immunotherapy (SLIT) trial at the Vienna Challenge Chamber (VCC) were included. Subjects had either received placebo (n = 22), low-dose HDM (n = 29) or high-dose HDM specific sublingual immunotherapy (n = 26) daily for 24 weeks. Blood sampling was performed before and after 6 hours of HDM allergen exposure. Overall, specific airway allergen challenge resulted in a significant decrease in circulating erythrocytes and hematocrit (p < 0.001), and elevation of leukocytes (p < 0.001), particularly segmented neutrophils (p < 0.001). Gender had no significant effect on the observed changes in circulating blood cells. Erythrocytes decreased and neutrophil counts increased significantly after airway allergen challenge regardless of preceding immunotherapy. These findings imply a rapid systemic mobilization of neutrophils occurring within immediate type hypersensitivity response upon a specific allergen challenge, which is possibly inversely linked with the erythrocyte numbers.

Guideline recommendations on the use of allergen immunotherapy in house dust mite allergy: Time for a change?

Guidelines on the treatment of asthma, allergic rhinitis (AR), and allergen immunotherapy (AIT) lack recommendations for house dust mite (HDM) allergy. An expert panel reviewed current guidelines in the light of new data to assess whether guidelines could be improved. Most guidelines and key position papers did not provide specific recommendations on treatment of allergic asthma (AA) caused by HDM allergy, although some included AIT as a treatment option for AA in general. Around half of the guidelines stated that AIT with HDM extract was an effective treatment for AR, with several indicating sublingual immunotherapy as an option. This heterogeneity is caused by quality issues affecting studies of AIT with perennial allergens in patients with AA and AR, including use of different diagnosis and severity criteria, lack of consistent scoring or grading systems for primary and safety outcomes, and lack of consensus on treatment parameters. There is a need for well-designed clinical trials to serve as a basis for guideline recommendations. Although results from recent studies strengthen the evidence base for the efficacy and safety of sublingual immunotherapy in patients with HDM-induced AA and AR, their effect on subsequent guideline updates will depend on the methodology and evidence model used by each guideline.

A 12-week DBPC dose-finding study with sublingual monomeric allergoid tablets in house dust mite-allergic patients

BACKGROUND

In sublingual immunotherapy, optimal doses are a key factor for therapeutic outcomes. The aim of this study with tablets containing carbamylated monomeric house dust mite allergoids was to determine the most effective and safe dose.

METHODS

In this double-blind, placebo-controlled dose-finding study, 131 patients with house dust mite-induced allergic rhinoconjunctivitis were randomized to 12-week treatments with 300 UA/day, 1000 UA/day, 2000 UA/day, 3000 UA/day or placebo. Conjunctival provocation tests (CPT) were performed before, during and after treatment. The change in mean allergic severity (primary endpoint), calculated from the severity of the CPT reaction, and the proportion of patients with an improved CPT threshold (secondary endpoint) determined the treatment effect.

RESULTS

The mean allergic severity decreased in all groups, including the placebo group. It was lower in all active treatment groups (300 UA/day: 0.14, 1000 UA/day: 0.15, 2000 UA/day: 0.10, 3000 UA/day: 0.15) than in the placebo group (0.30). However, this difference was not statistically significant (P < 0.1). The percentage of patients with an improved CPT threshold was higher in the active treatment groups (300 UA/day: 73.9%; 1000 UA/day: 76.0%; 2000 UA/day: 88.5%; 3000 UA/day: 76.0%) than in the placebo group (64.3%). The difference between placebo and 2000 UA/day was statistically significant (P = 0.04). In 13 (10%) exposed patients, a total of 20 treatment-related adverse events of mild severity were observed.

CONCLUSIONS

The 12-week daily treatment using 2000 UA/day monomeric allergoid sublingual tablets is well tolerated and reduces the CPT reaction in house dust mite-allergic patients.

Efficacy of Sublingual Immunotherapy for House Dust Mite-Induced Allergic Rhinitis: A Meta-Analysis of Randomized Controlled Trials

Purpose

Allergic rhinitis (AR) has become a global issue for a large part of the general population. Sublingual immunotherapy (SLIT) has been used extensively to treat persistent allergic rhinitis (PAR). Although systematic reviews have confirmed the effectiveness of SLIT for the treatment of AR, a considerable number of studies using extracts of house dust mites (HDMs) for immunotherapy found no consensus on basic treatment parameters and questioned the efficacy of SLIT.

Methods

In this study, we evaluated SLIT for PAR by a meta-analysis of randomized controlled trials (RCTs). Medline, Embase, and Cochrane Library database searches were performed for RCTs on the treatment of PAR by SLIT that assessed clinical outcomes related to efficacy through May 2016. Descriptive and quantitative information was abstracted. An analysis was performed with standardized mean differences (SMDs) under a fixed or random effects model. Subgroup analyses were performed. Heterogeneity was assessed using the I² metric.

Results

In total, 25 studies were eligible for inclusion in the meta-analysis for symptom scores and 15 studies for medication scores. SLIT was significantly different from the controls for symptom scores (SMD=1.23; 95% confidence interval [CI]=1.74 to 0.73; P<0.001). For medication scores, significant differences for SLIT were also observed versus the controls (SMD=-1.39; 95% CI=-1.90 to -0.88; P<0.001).

Conclusions

Our meta-analysis indicates that SLIT provided significant symptom relief and reduced the need for medications in PAR. In this study, significant evidence was obtained despite heterogeneity with regard to the use of mite extract. Specifically, the mite extract used was provided by the patients with PAR. Furthermore, to confirm both the objective outcomes and the effective doses of HDM allergen extracts, experimental data should be obtained from large high-quality population-based studies.

Efficacy of house dust mite sublingual immunotherapy tablet in North American adolescents and adults in a randomized, placebo-controlled trial

BACKGROUND

The house dust mite (HDM) sublingual immunotherapy (SLIT) tablet (MK-8237; Merck & Co, Kenilworth, NJ/ALK-Abelló, Hørsholm, Denmark) has demonstrated beneficial effects on allergic rhinoconjunctivitis and asthma outcomes in European trials.

OBJECTIVE

This is the first trial to assess the efficacy/safety of HDM SLIT-tablets in North American subjects with HDM-induced allergic rhinitis with or without conjunctivitis (AR/C).

METHODS

In this double-blind, multicenter trial (NCT01700192) 1482 subjects (aged ≥12 years) with HDM-induced AR/C with or without asthma were randomized to a daily SQ HDM SLIT-tablet (12 SQ-HDM dose) or placebo for up to approximately 52 weeks. A rhinitis daily symptom score (DSS; 4 nasal symptoms, maximum score = 12) of 6 or greater, or 5 or greater with 1 symptom being severe, on 5 of 7 consecutive days before randomization was required. The primary end point was the average total combined rhinitis score, which was defined as the rhinitis DSS plus rhinitis daily medication score (DMS), during the last 8 treatment weeks.

RESULTS

Treatment with 12 SQ-HDM improved the total combined rhinitis score by 17% (95% CI, 10% to 25%) versus placebo. Improvements versus placebo in the secondary end points of average rhinitis DSS, rhinitis DMS, total combined rhinoconjunctivitis score, and visual analog scale-assessed AR/C symptoms were 16%, 18%, 17%, and 16%, respectively. All nominal P values were less than .001 versus placebo, except rhinitis DMS (P = 0.15). No treatment-related adverse events meeting the International Council on Harmonization definition of a serious adverse event were reported; 1 nonserious treatment-related systemic allergic reaction occurred (assessed as moderate intensity) at first administration under medical supervision and was treated with epinephrine.

CONCLUSIONS

In the first North American trial of use of a SLIT-tablet for HDM allergy, 12 SQ-HDM was well tolerated and improved HDM-induced rhinitis symptoms in adults and adolescents.

Allergic Rhinitis: Mechanisms and Treatment

The prevalence of allergic rhinitis (AR) has been estimated at 10% to 40%, and its economic burden is substantial. AR patients develop specific immunoglobulin E (IgE) antibody responses to indoor and outdoor environmental allergens with exposure over time. These specific IgE antibodies bind to high-affinity IgE receptors on mast cells and basophils. Key outcome measures of therapeutic interventions include rhinitis symptom control, rescue medication requirements, and quality-of-life measures. A comprehensive multiple modality treatment plan customized to the individual patient can optimize outcomes.

The Future of Sublingual Immunotherapy in the United States

Sublingual immunotherapy (SLIT) is a safe and effective treatment for allergic rhinitis (AR) and allergic rhinoconjunctivitis (ARC). The Food and Drug Administration (FDA) in the USA has approved three SLIT tablets for the treatment of AR and ARC in relation to pollen. Specifically, Grastek® and Oralair® are two formulations approved to treat patients suffering with AR/ARC to grass pollen, and Ragwitek™ is a formulation approved to treat patients suffering with AR/ARC to ragweed pollen. Although these approvals provide support for physicians to prescribe SLIT, barriers to prescribing SLIT still remain such as FDA approval for additional formulations, a standard dose and dosing schedule, and cost/insurance coverage. In order to further support the use of SLIT, research is currently being conducted to expand the indication for SLIT to other common comorbidities to AR/ARC. For example, allergic asthma, food allergies, and atopic dermatitis are other diseases which are being explored. The future of SLIT in the USA is unknown; however, education will be necessary for both providers and patients.

House Dust Mite Respiratory Allergy: An Overview of Current Therapeutic Strategies

Although house dust mite (HDM) allergy is a major cause of respiratory allergic disease, specific diagnosis and effective treatment both present unresolved challenges. Guidelines for the treatment of allergic rhinitis and asthma are well supported in the literature, but specific evidence on the efficacy of pharmacotherapy treatment for known HDM-allergic patients is weaker. The standard diagnostic techniques--skin prick test and specific IgE testing--can be confounded by cross-reactivity. However, component-resolved diagnosis using purified and recombinant allergens can improve the accuracy of specific IgE testing, but availability is limited. Treatment options for HDM allergy are limited and include HDM avoidance, which is widely recommended as a strategy, although evidence for its efficacy is variable. Clinical efficacy of pharmacotherapy is well documented; however, symptom relief does not extend beyond the end of treatment. Finally, allergen immunotherapy has a poor but improving evidence base (notably on sublingual tablets) and its benefits last after treatment ends. This review identifies needs for deeper physician knowledge on the extent and impact of HDM allergy in respiratory disease, as well as further development and improved access to molecular allergy diagnosis. Furthermore, there is a need for the development of better-designed clinical trials to explore the utility of allergen-specific approaches, and uptake of data into guidance for physicians on more effective diagnosis and therapy of HDM respiratory allergy in practice.

Mite-Allergic Rhinitis: How to Evaluate Clinical Efficacy in Allergen-Specific Immunotherapy Trials?

House dust mite (HDM) allergen exposure is the most important cause of perennial allergic rhinitis and/or asthma. Although allergen-specific immunotherapy (AIT) with HDM is well established, published studies have been characterized by substantial heterogeneity in clinical endpoints. Standardization in measuring clinical efficacy is required. Moreover, when designing an AIT trial with HDM allergens, several considerations have to be taken into account. The history of HDM allergy is less clear cut than the typical history of pollen allergy. In addition, clinical features of HDM allergy may differ from those of pollen allergy. Moreover, although not easily measurable, fluctuation in allergen exposure may cause variation in symptom severity and determine the timing of assessment of clinical effects of HDM AIT. Key points 1. A combined symptom and medication score (CSMS) is recommended as standard for the primary endpoint in future house dust mite (HDM) allergen-specific immunotherapy trials. 2. The diagnosis of HDM allergy is based on a carefully taken history in combination with sensitization to HDM allergens. 3. Eye symptoms are less prominent in patients with HDM-induced allergic rhinitis. Nasal symptoms, but not eye symptoms, should be included in the CSMS and in symptom scores as well. 4. As methods to determine allergen exposure vary and the efficacy of environmental control is a matter of debate, a practical approach consists of restraining patients from implementing HDM-reducing measures, such as removing carpets and introducing anti-mite covers, after the start of the study. 5. Efficacy evaluation in the period with the highest exposure to mites is recommended.