Maintenance dosing for sublingual immunotherapy by prominent European allergen manufacturers expressed in bioequivalent allergy units

Delivery options for sublingual immunotherapy for allergic rhinoconjunctivitis: clinical considerations for North America

Background: Sublingual immunotherapy (SLIT) can be delivered via tablets (SLIT-T) or aqueous drops (SLIT-D). SLIT-D dosing recommendations using North American extracts were published in 2015. We review the 2015 recommendations in the context of recent research, and compare and contrast dosing, efficacy, safety, adherence, and cost of SLIT-T and SLIT-D for allergic rhinoconjunctivitis (ARC) in North America. Methods: Randomized controlled trials (RCT) of SLIT-D and SLIT-T trials were identified by a systematic PubMed search through March 1, 2022. Results: Dose-finding studies have been conducted for all approved SLIT-T; efficacy in North American populations was demonstrated in 11 RCTs. Approved SLIT-T are uniform internationally. Few dose-finding studies for SLIT-D have been conducted using North American extracts; efficacy was demonstrated in 2 RCTs. Extrapolation of dosing from SLIT-D studies conducted with extracts from other geographic regions is unreliable. Since the 2015 SLIT-D dosing recommendations, no new RCTs of SLIT-D have been conducted with North American extracts, whereas 6 SLIT-T RCTs have since been conducted in North America. Local allergic reactions are the most common adverse events with SLIT-T and SLIT-D, but both can induce systemic allergic reactions. Adherence to SLIT-D and SLIT-T remains a challenge. Patients must pay for SLIT-D directly, whereas SLIT-T is usually covered by insurance. Conclusion: As part of shared decision-making, patients should be informed about the scientific evidence supporting the use of SLIT-T and SLIT-D for ARC.

Comparison of weight per volume and protein nitrogen units in non-standardized allergen extracts: implications for prescribing subcutaneous immunotherapy

Background

Allergen extracts used in subcutaneous immunotherapy can be standardized or non-standardized. Standardized extracts are available in specific biological potencies, presumably making their biological activity more consistent. The majority of allergen extracts are non-standardized and may have less consistent potencies. Non-standardized extracts are labeled as weight per volume or protein nitrogen units (PNUs). Neither method provides direct information regarding the extract’s biologic potency. The purpose of this study was to compare weight per volume versus PNU concentrations for 4 non-standardized allergen extracts prepared by two allergen manufacturers. The potencies were compared to current North American practice recommendations.

Methods

The weight per volume and PNU values were provided for 4 non-standardized extracts—birch, short ragweed, dog hair and Alternaria—from HollisterStier and Stallergenes Greer. Weight per volume and PNU concentrations were compared for each of these extracts from both manufacturers. From the raw data, we calculated the corresponding PNU values for a weight per volume of 1:100 and 1:200 for each extract. Similarly, we calculated the corresponding weight per volume including a range of PNU values, for 1000, 2000, 3000, 4000 and 5000 PNU/ml.

Results

Birch extract has low PNU concentration, below 5000, for a weight per volume of 1:200 for both HollisterStier and Stallergenes Greer. In contrast, for both HollisterStier and Stallergenes Greer ragweed extract, a weight per volume of 1:200 corresponds to a PNU concentration greater than 5000. Dog extract for a weight per volume of 1:200, and even for 1:100, corresponds to very low PNUs for both companies. For Alternaria, corresponding PNU concentrations for HollisterStier is low at only 500 while over 5000 for Stallergenes Greer.

Conclusions

Our results show variability when comparing weight per volume and PNU concentrations for both Hollister-Stier and Stallergenes Greer products. We suggest selecting a PNU dose that corresponds to a weight per volume of 1:200 as this may improve patient safety. Our recommendations for starting PNU dose for the four non-standardized extracts are 1500 for birch, 5000 for ragweed, 25 for dog, and 500 for Alternaria when using HollisterStier products; 2300 for birch, 5000 for ragweed, 1200 for dog, and 5000 for Alternaria when using Stallergenes Greer products. If the starting PNU concentration is considerably below 5000 for a weight per volume of 1:200 slow up-titration is advised. Conversely, for PNU concentrations above 5000 for weight per volume of 1:200 we suggest a maintenance dose of 5000 PNU.

Personalized medicine for allergy treatment: Allergen immunotherapy still a unique and unmatched model

The introduction of personalized medicine (PM) has been a milestone in the history of medical therapy, because it has revolutionized the previous approach of treating the disease with that of treating the patient. It is known today that diseases can occur in different genetic variants, making specific treatments of proven efficacy necessary for a given endotype. Allergic diseases are particularly suitable for PM, because they meet the therapeutic success requirements, including a known molecular mechanism of the disease, a diagnostic tool for such disease, and a treatment blocking the mechanism. The stakes of PM in allergic patients are molecular diagnostics, to detect specific IgE to single-allergen molecules and to distinguish the causative molecules from those merely cross-reactive, pursuit of patient's treatable traits addressing genetic, phenotypic, and psychosocial features, and omics, such as proteomics, epi-genomics, metabolomics, and breathomics, to forecast patient's responsiveness to therapies, to detect biomarker and mediators, and to verify the disease control. This new approach has already improved the precision of allergy diagnosis and is likely to significantly increase, through the higher performance achieved with the personalized treatment, the effectiveness of allergen immunotherapy by enhancing its already known and unique characteristics of treatment that acts on the causes.

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.

Clinical aspects of sublingual immunotherapy tablets and drops

BACKGROUND

Sublingual immunotherapy (SLIT) is administered via tablets (SLIT-T) or liquid drops (SLIT-D). In North America, currently 4 SLIT-T formulations are approved by the US Food and Drug Administration for allergy immunotherapy, and SLIT-D is an off-label use of subcutaneous immunotherapy (SCIT) extracts.

OBJECTIVE

To compare and contrast aspects of SLIT-T and SLIT-D, including physical characteristics, mechanism of action, dosing, efficacy, safety, adherence, and cost.

DATA SOURCES

PubMed literature review (no limits), product prescribing information, and manufacturer websites.

STUDY SELECTIONS

Publications related to physical characteristics, mechanism of action, dosing, efficacy, safety, and adherence.

RESULTS

Published evidence indicates that tablet and drop formulations differ in regard to physical characteristics, dosing, and strength of evidence for efficacy. Whether there are any differences in absorption and mechanism of action between the 2 formulations is currently unknown. Optimal dosing, efficacy, and safety have been established for SLIT-T. In contrast, in North America there is little support for efficacy of SLIT-D from randomized double-blind, placebo-controlled trials, and dose ranges have not been appropriately evaluated. SLIT-T treats a single allergen, whereas in the United States SLIT-D often contains multiple allergens to treat polysensitization. The safety profiles of SLIT-T and SLIT-D appear similar, and both formulations are considered safer than SCIT.

CONCLUSION

Professional guidelines should make a clear distinction between SLIT-T and SLIT-D in their recommendations to minimize confusion with the umbrella term SLIT.

Ragweed Pollen Allergy: Burden, Characteristics, and Management of an Imported Allergen Source in Europe

Ambrosia artemisiifolia, also known as common or short ragweed, is an invasive annual flowering herbaceous plant that has its origin in North America. Nowadays, ragweed can be found in many areas worldwide. Ragweed pollen is known for its high potential to cause type I allergic reactions in late summer and autumn and represents a major health problem in America and several countries in Europe. Climate change and urbanization, as well as long distance transport capacity, enhance the spread of ragweed pollen. Therefore ragweed is becoming domestic in non-invaded areas which in turn will increase the sensitization rate. So far 11 ragweed allergens have been described and, according to IgE reactivity, Amb a 1 and Amb a 11 seem to be major allergens. Sensitization rates of the other allergens vary between 10 and 50%. Most of the allergens have already been recombinantly produced, but most of them have not been characterized regarding their allergenic activity, therefore no conclusion on the clinical relevance of all the allergens can be made, which is important and necessary for an accurate diagnosis. Pharmacotherapy is the most common treatment for ragweed pollen allergy but fails to impact on the course of allergy. Allergen-specific immunotherapy (AIT) is the only causative and disease-modifying treatment of allergy with long-lasting effects, but currently it is based on the administration of ragweed pollen extract or Amb a 1 only. In order to improve ragweed pollen AIT, new strategies are required with higher efficacy and safety.

Allergen manufacturing and quality aspects for allergen immunotherapy in Europe and the United States: An analysis from the EAACI AIT Guidelines Project

Adequate quality is essential for any medicinal product to be eligible for marketing. Quality includes verification of the identity, content and purity of a medicinal product in combination with a specified production process and its control. Allergen products derived from natural sources require particular considerations to ensure adequate quality. Here, we describe key aspects of the documentation on manufacturing and quality aspects for allergen immunotherapy products in the European Union and the United States. In some key parts, requirements in these areas are harmonized while other fields are regulated separately between both regions. Essential differences are found in the use of Reference Preparations, or the requirement to apply standardized assays for potency determination. As the types of products available are different in specific regions, regulatory guidance for such products may also be available in one specific region only, such as for allergoids in the European Union. Region-specific issues and priorities are a result of this. As allergen products derived from natural sources are inherently variable in their qualitative and quantitative composition, these products present special challenges to balance the variability and ensuring batch-to-batch consistency. Advancements in scientific knowledge on specific allergens and their role in allergic disease will consequentially find representation in future regulatory guidelines.

EAACI Guidelines on Allergen Immunotherapy: Allergic rhinoconjunctivitis

Allergic rhinoconjunctivitis (AR) is an allergic disorder of the nose and eyes affecting about a fifth of the general population. Symptoms of AR can be controlled with allergen avoidance measures and pharmacotherapy. However, many patients continue to have ongoing symptoms and an impaired quality of life; pharmacotherapy may also induce some side-effects. Allergen immunotherapy (AIT) represents the only currently available treatment that targets the underlying pathophysiology, and it may have a disease-modifying effect. Either the subcutaneous (SCIT) or sublingual (SLIT) routes may be used. This Guideline has been prepared by the European Academy of Allergy and Clinical Immunology's (EAACI) Taskforce on AIT for AR and is part of the EAACI presidential project "EAACI Guidelines on Allergen Immunotherapy." It aims to provide evidence-based clinical recommendations and has been informed by a formal systematic review and meta-analysis. Its generation has followed the Appraisal of Guidelines for Research and Evaluation (AGREE II) approach. The process included involvement of the full range of stakeholders. In general, broad evidence for the clinical efficacy of AIT for AR exists but a product-specific evaluation of evidence is recommended. In general, SCIT and SLIT are recommended for both seasonal and perennial AR for its short-term benefit. The strongest evidence for long-term benefit is documented for grass AIT (especially for the grass tablets) where long-term benefit is seen. To achieve long-term efficacy, it is recommended that a minimum of 3 years of therapy is used. Many gaps in the evidence base exist, particularly around long-term benefit and use in children.

Bioavailability of House Dust Mite Allergens in Sublingual Allergy Tablets Is Highly Dependent on the Formulation

BACKGROUND

In sublingual immunotherapy (SLIT), the immune system is addressed by solubilized allergen that interacts with immunocompetent cells of the oral mucosa, the efficiency of which is governed by 2 main factors of SLIT allergen bioavailability: the allergen concentration and the mucosal contact time. Recently, 3 house dust mite (HDM) SLIT tablets were developed that differ with regard to allergen content, nominal strength (maintenance doses: 6 SQ-HDM/10,000 Japanese Allergen Units [JAU], 12 SQ-HDM/ 20,000 JAU, and 300 IR/57,000 JAU), and formulation (freeze-dried/compressed). Here, the importance of the SLIT tablet formulation for HDM major allergen bioavailability is examined.

METHODS

The HDM major allergen content, tablet disintegration times, and allergen release kinetics were determined. Dissolution kinetics (allergen concentration vs. time) of Der f 1, Der p 1, and Der 2 were measured. Area under the curve (AUC) was used as a surrogate parameter for allergen bioavailability.

RESULTS

The release of HDM major allergens from the freeze-dried tablets was complete after 30 s, while only partial release was achieved with the compressed tablets, even after prolonged dissolution. At 1 min, i.e., the recommended sublingual holding time for the freeze-dried tablets, the allergen bioavailability (AUC) of the compressed 300 IR/57,000 JAU tablet was 4.7-fold (Der f 1), 10.8-fold (Der p 1), and 23.6-fold (Der 2) lower than that of the freeze-dried 12 SQ-HDM/20,000 JAU tablet and similar to (Der f 1) and 5.3-fold (Der p 1) and 12.5-fold (Der 2) lower than that of the freeze-dried 6 SQ-HDM/10,000 JAU tablet.

CONCLUSIONS

SLIT tablet allergen bioavailability depends highly on the tablet formulation. Only the fast-dissolving freeze-dried tablets provide maximal delivery of soluble allergens and achieve allergen concentrations that reflect the nominal tablet strengths within the recommended sublingual holding time.

Major allergen content consistency of SQ house dust mite sublingual immunotherapy tablets and relevance across geographic regions

BACKGROUND

Consistency in composition and potency, particularly regarding major allergens, is crucial for the quality of extracts for allergen immunotherapy.

OBJECTIVE

To characterize the major allergen composition of house dust mite (HDM) extracts commercially available in the United States and the SQ HDM sublingual immunotherapy (SLIT) tablet, and to relate the composition to patient sensitization patterns.

METHODS

Der 1/Der 2 ratios were determined in 10,000- and 30,000-AU/mL HDM extracts from 5 US companies and the SQ HDM SLIT-tablet. Allergen content was analyzed by enzyme-linked immunosorbent assay and compared with an in-house reference. Sensitivity toward Der p 1, Der p 2, and Der p 10 was determined in serum from randomly selected subgroups of 220 individuals from North American and European SQ HDM SLIT-tablet trials.

RESULTS

Mean Der 1/Der 2 ratios in US HDM extracts ranged from 0.4 to 20.5. For the SQ HDM SLIT-tablet (20 batches), variability did not exceed 12% regarding content of Der f 1 (SD, 11.9%; 95% confidence interval [CI], 0.94-1.06), Der p 1 (SD, 6.1%; 95% CI, 0.97-1.03), and combined Der 2 allergen (SD, 6.4%; 95% CI, 0.97-1.03), indicating a consistent Der 1/Der 2 ratio. High allergen sensitivity frequencies toward Der p 1 and Der p 2 were observed regardless of geographic region. Efficacy of the SQ HDM SLIT-tablet has been demonstrated in 5 clinical trials.

CONCLUSION

The SQ HDM SLIT-tablet has efficacy potential for a broad range of patients because it includes a consistent 1:1 ratio of the 2 major HDM allergens to which individuals were most frequently sensitized across geographic regions. Efficacy has been demonstrated.

Minor allergen patterns in birch pollen allergen products-A question of pollen?

BACKGROUND

Contrary to the scientific differentiation between major and minor allergens, the regulatory framework controlling allergen products in the EU distinguishes relevant and non-relevant allergens. Given the lack of knowledge on their clinical relevance, minor allergens are usually not controlled by allergen product specifications. Especially, in birch pollen (BP) allergen products, minor allergens are commonly disregarded.

OBJECTIVES

To quantify three minor allergens in BP allergen products from different manufacturers and to assess the influence of the utilized BP on minor allergen patterns.

METHODS

Apart from common quality parameters such as Bet v 1 content, Bet v 4, Bet v 6 and Bet v 7 were quantified in 70 BP allergen product batches from six manufacturers, using ELISA systems developed in-house. Batch-to-batch variability was checked for agreement with a variability margin of 50%-200% from mean of the given batches for individual allergen content. Subsequently, minor allergen patterns were generated via multidimensional scaling and related to information on the pollen lots used in production of the respective product batches.

RESULTS

Like the already established Bet v 4 ELISA, the ELISA systems for quantification of Bet v 6 and Bet v 7 were successfully validated. Differences in minor allergen content between products and batch-to-batch consistency were observed. Correlations between minor and major allergen content were low to moderate. About 20% of batches exceeded the variability margin for at least one minor allergen. Interestingly, these fluctuations could not in all cases be linked to the use of certain BP lots.

CONCLUSIONS AND CLINICAL RELEVANCE

The impact of the observed minor allergen variability on safety and efficacy of BP allergen products can currently not be estimated. As the described differences could only in few cases be related to the used pollen lots, it is evident that additional factors influence minor allergens in BP allergen products.

Quality control of house dust mite extracts by broad-spectrum profiling of allergen-related enzymatic activities

BACKGROUND

Diagnosis and immunotherapy of allergy against mites is based on complex extracts from large-scale cultures. However, the analysis of their composition using specific antibodies is limited. By taking advantage of the prevailing enzymatic nature of mite allergens, we have developed a broad-spectrum biochemical method for the standardization of native mite products.

METHODS

Microplate-based assays have been implemented for thirteen Dermatophagoides pteronyssinus enzymatic activities, associated with Der p 1, 3, 4, 6, 8, 9, 15 and 20 allergens. The dynamics of these activities along culture growth, and their profile in purified fractions (bodies and faeces) and international reference standards (WHO/IUIS, two CBER/FDA), have been characterized. The stability of enzymatic activities and major allergens under stress conditions (40°C) has been assessed in the presence/absence of specific protease inhibitors.

RESULTS

The analysis of enzymatic activities revealed distinct profiles along culture growth and between fractions (bodies and faeces). Remarkable differences were found when comparing international reference standards, being consistent with their source material (purified bodies or whole cultures). After 72 h at 40°C, only trypsin and alpha-amylase maintained high activity. Notably, the prominent role of trypsins in the hydrolytic degradation of major allergens is demonstrated by the use of inhibitors.

CONCLUSIONS

Our method offers a robust approach to assess the complexity of mite extracts and highlights the critical importance of source materials for the composition and stability of finished products. The implementation of this approach in industry-based quality control procedures would contribute to the standardization of allergenic extracts used for diagnosis and immunotherapy.

Similar biological activity in skin prick test for Oralair® (8200 BAU) and Grazax® (6200 BAU) reinforces effective SLIT dosing level

In Europe, allergen extracts are standardized based on skin prick wheal size in 20-30 allergic subjects. To understand the biological activity of clinically effective Sublingual immunotherapy, we used this method to determine the biological activity of solution and tablet Timothy grass pollen (TIM) extracts, compared to an FDA-approved extract (Reference) of 10 000 BAU/ml. Blinded, quadruplicate skin prick tests with concentrate and three serial half-log dilutions allowed the construction of a semilogarithmic regression line per extract. Bioequivalent allergy units (BAU) values were obtained from the comparison with reference. Extracts and dilutions showed a neat linear dose response (all: R² > 0.98) in 33 rhinitis patients. Relative potencies: Staloral^® 12 000 BAU/ml, Soluprick^® 10 300 BAU/ml, Oralair^® 8200 BAU, and Grazax^® 6200 BAU. Even though all extract concentrates differed in wheal size (P = 0.01-0.001), Grazax^® producing a 25% smaller wheal size than Oralair^® , and the biological activity of these clinically effective TIM tablets led in the same range (6200-8200 BAU; 0.92-1.23 cm² ). SLIT dose-finding studies for other pollens might start with allergen extracts producing 1.1 cm² wheal surface.

Standardization of allergen products: 3. Validation of candidate European Pharmacopoeia standard methods for quantification of major birch allergen Bet v 1

BACKGROUND

The BSP090 project aims at establishing European Pharmacopoeia Reference Substances in combination with the corresponding ELISA methods for the quantification of major allergens in allergen products. Two sandwich ELISAs proved suitable for quantification of Bet v 1, the major birch pollen allergen, in preceding phases of BSP090.

METHODS

Two Bet v 1-specific ELISA systems were compared with respect to accuracy and precision in a ring trial including 13 laboratories. Model samples containing recombinant rBet v 1.0101 as well as native birch pollen extracts were measured independently at least three times in each facility. The assessment was completed with a comparative quantification of Bet v 1 in 30 marketed birch allergen products in one laboratory, simulating the future use as reference method.

RESULTS

In the collaborative study, both candidate ELISAs confirmed their suitability to quantify recombinant and native Bet v 1. ELISA-A showed higher precision and lower interlaboratory variability, yet ELISA-B exhibited slightly higher accuracy. Subsequent parallel measurement of Bet v 1 in a panel of 'real-life' birch allergen products indicated better repeatability of ELISA-B. Both systems detected substantial differences in Bet v 1 content between allergen products, but the effect was more pronounced using ELISA-B due to persistently higher values compared to ELISA-A.

CONCLUSIONS

In the collaborative study, no deciding differences were observed between the two candidate ELISAs. Further comparison under conditions simulating the intended use combined with the criterion of long-term availability enabled the selection of one Bet v 1-specific ELISA for proposal as European Pharmacopoeia standard method.

Patient selection for subcutaneous versus sublingual immunotherapy

PURPOSE OF REVIEW

With the Food and Drug Administration's approval of sublingual allergen-specific immunotherapy (SL-AIT) tablets for grass and ragweed pollen, SL-AIT is progressively gathering importance not only in Europe, but also in the United States and other parts of the world. We reviewed issues related to the selection of patients for the sublingual or the subcutaneous route for allergic patients, based on what has been published since January 2014 on subcutaneous-versus-SL-AIT efficacy, safety and other issues. (Figure is included in full-text article.)

RECENT FINDINGS

As patient's adherence seems one of the major problems in real-life AIT, investigators have sought how to enhance AIT simplicity by changing the route to home-administrated SL-AIT, and by shortening the subcutaneous-allergen-specific immunotherapy (SC-AIT) build-up or maintenance phase. The latter was safe with several hypoallergenic extracts. As for SL-AIT, double blind placebo-controlled large trials in patients with allergic rhinitis and asthma have shown the efficacy and safety of ragweed pollen and house dust mite SLIT tablets and highly concentrated liquid formulations, primarily in adults. A large trial with SLIT in 3-year-old children was effective.

SUMMARY

With the improvement of SL-AIT efficacy, the selection of SC-versus-SL-AIT will probably increasingly be based not on efficacy, but on practical aspects, without losing sight of which SL-AIT products have proven efficacy.

Standardization and Regulation of Allergen Products in the European Union

Product-specific standardization is of prime importance to ensure persistent quality, safety, and efficacy of allergen products. The regulatory framework in the EU has induced great advancements in the field in the last years although national implementation still remains heterogeneous. Scores of methods for quantification of individual allergen molecules are developed each year and also the challenging characterization of chemically modified allergen products is progressing. However, despite the unquestionable increase in knowledge and the subsequent improvements in control of quality parameters of allergen products, an important aim has not been reached yet, namely cross-product comparability. Still, comparison of allergen product potency, either based on total allergenic activity or individual allergen molecule content, is not possible due to a lack of standard reference preparations in conjunction with validated standard methods. This review aims at presenting the most recent developments in product-specific standardization as well as activities to facilitate cross-product comparability in the EU.

Math-free guides for glycerin and allergens at variable subcutaneous injection volumes: How's my dosing? Update

BACKGROUND

Current summaries of effective maintenance dose ranges for subcutaneous immunotherapy (SCIT) are based on administration of 0.5-mL volumes. Extract formulations delivering equivalent dose ranges for practices using different injection volumes have not been reported, and calculation of the final glycerin concentrations in these solutions remains an inconvenient and repetitive process.

OBJECTIVE

To create math-free guides for allergen doses and glycerin concentrations that identify the extract concentrate volumes required to deliver doses within the ranges cited in the 2011 immunotherapy practice parameters for clinicians using 5.0-mL maintenance vials and injection volumes ranging from 0.2 to 1.0 mL.

METHODS

Algebraic calculations were performed to determine the specific combinations of extract concentrate strengths, volumes of these products in patient vaccines, and injection volumes needed for administration of target allergen doses spanning the current SCIT practice parameter recommendations.

RESULTS

For each product or group (nonstandardized extracts), tables were constructed to define the allergen doses provided by various combinations of extract concentrate volumes and injection volumes. The values within the effective dose ranges for each product were highlighted to facilitate comparisons of specific conditions relevant to allergy specialists. Glycerin tables were also created to permit convenient assessments of the final concentrations of this stabilizer in patient prescriptions.

CONCLUSION

SCIT dosing and glycerin tables are useful tools to assist allergists with practice decisions that involve variable patient formulas and injection volumes and can help identify suitable conditions for treatment of patients presenting with diverse allergen sensitivities and specificity profiles.

Variation in allergen content in sublingual allergen immunotherapy with house dust mites

Background

Allergen immunotherapy is a treatment modality which can be applied using different vaccines. The aim of this study was to quantify and compare the allergen content of different house dust mites (HDM)’ sublingual treatments and to review the evidence on their efficacy.

Methods

Five sublingual allergen immunotherapy (SLIT) products were ordered and purchased at an ordinary pharmacy and masked for blinding before the study was started. Detection of Dermatophagoides pteronyssinus and Dermatophagoides farinae allergens Der p 1, Der f 1, Der p 2 and Der f 2 was carried out by immunoblotting and fluorescent multiplex. A literature search for meta‐analyses and systematic reviews that included SLIT‐HDM products was performed.

Results

Der p 1 concentrations ranged from 0.6 to 14.5 μg/ml; similar figures were found for Der f 1 that ranged from 0.2 to 12.4 μg/ml. Der p 2+ Der f 2 ranged from 0.2 to 1.5 μg/ml. Data on efficacy are scarce for most of the five products.

Conclusions

Substantial variations regarding allergen content were found among these five SLIT‐HDM products. Therefore, it can be necessary to guarantee the quality of the SLIT‐HDM products and to demonstrate their effectiveness before they are marketed. It seems necessary, for the moment, to take into account these characteristics of the products before prescribing.

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.

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.

"The value of pre- and co-seasonal sublingual immunotherapy in pollen-induced allergic rhinoconjunctivitis"

Allergen immunotherapy (AIT) is a guidelines-approved, disease-modifying treatment option for respiratory allergies, including allergic rhinitis (AR) induced by pollen. The various AIT regimens employed to date in pollen-induced AR can be classified as continuous (i.e. year-round) or discontinuous (i.e. pre-seasonal alone, co-seasonal alone or pre- and co-seasonal). Pre-and co-seasonal regimens are typically used for sublingual allergen immunotherapy (SLIT) and have economic and compliance advantages over perennial (year-round) regimens. However, these advantages must not come at the expensive of poor efficacy or safety. The results of recent double-blind, placebo-controlled, randomized clinical trials show that pre- and co-seasonal SLIT is safe and effective in patients with AR induced by grass pollen (treated with a tablet formulation) or by birch pollen (treated with a liquid formulation). Progress in SLIT has been made in defining the optimal dose of major allergen, the administration frequency (daily), the duration of pre-seasonal treatment (four months) and the number of treatment seasons (at least three). Post-marketing, "real-life" trials of pre- and co-seasonal birch or grass pollen SLIT regimens have confirmed the efficacy and safety observed in the clinical trials. In the treatment of pollen-induced AR, pre- and co-seasonal SLIT regimens appear to be at least as effective and safe as perennial SLIT regimens, and are associated with lower costs and good compliance. Good compliance may mean that pre- and co-seasonal SLIT regimens are inherently more effective and safer than perennial SLIT regimens. When considering the pre- and co-seasonal discontinuous regimen in particular, a 300 IR five-grass-pollen formulation is the only SLIT tablet with a clinical development programme having provided evidence of short-term, sustained and post-treatment efficacy.

Japanese Society of Allergology task force report on standardization of house dust mite allergen vaccines - secondary publication

BACKGROUND

In the 1990s, the Japanese Society of Allergology (JSA) standardized Japanese cedar pollen allergen vaccines. In the present study, the task force for house dust mite (HDM) allergen standardization of the Committee for Allergens and Immunotherapy of JSA reports the standardization of HDM allergen vaccines in Japan.

METHODS

In vivo allergenic potency was determined by intradermal testing of 51 Japanese adults with positive serum specific IgE to HDM allergens. In vitro total IgE binding potency was analyzed by competition ELISA using a pooled serum, with sera obtained from 10 allergic patients. The amounts of HDM group 1 (Der 1) and group 2 major allergens in eight HDM allergen extracts were measured by sandwich ELISAs. Correlation between the in vitro total IgE binding potency and major allergen levels was analyzed.

RESULTS

We selected a JSA reference HDM extract and determined its in vivo allergenic potency. The in vitro total IgE binding potency significantly correlated with Der 1 content, group 2 allergen content, and their combined amount, indicating that measurement of major allergen contents can be used as a surrogate in vitro assay.

CONCLUSIONS

The task force determined the in vivo allergenic potency (100,000 JAU/ml) and Der 1 content (38.5 μg/ml) of the JSA reference HDM extract, selected the measurement of Der 1 content as the surrogate in vitro assay, and decided that manufacturers can label a HDM allergen extract as having a titer of 100,000 JAU/ml if it contains 22.2-66.7 μg/ml of Der 1.

In vitro evaluation of allergen potencies of commercial house dust mite sublingual immunotherapy reagents

Purpose

The clinical efficacy of allergen-immunotherapy is known to be dose dependent. However, optimal maintenance dosage has not yet been determined for sublingual immunotherapy (SLIT). Furthermore, since companies adopt their own units for expression of allergenicity, the allergen concentrations of individual reagents cannot be compared easily. We sought to measure and compare the allergenicities of 3 commercially available house dust mite (HDM) SLIT regents and a subcutaneous immunotherapy reagent.

Methods

We measured the HDM allergenic potency of the maintenance dosages of three SLIT reagents: Staloral® (300 index of reactivity [IR] /mL, recommended maintenance dosage [MD]: 120 IR), SLITone® (1,000 standard therapeutic unit [STU]/mL, recommended MD: 200 STU), Wolwopharma® (100 µg/mL, recommended MD: 20 µg), and subcutaneous immunotherapy regents of Hollister-Stier (10,000 allergy unit [AU] /mL). The allergenic potency was assessed by measuring the total protein concentrations, mite group 1 and 2 allergens using 2-site ELISA, and an inhibition test against IgE specific to Dermatophagoides farinae and Dermatophagoides pteronyssinus.

Results

The protein content of the Wolwopharma® reagent was 1.5-261.4 times higher than that of the other 2 SLIT reagents. The concentration of group 1 major allergens in Staloral® (132.03 µg/mL) was 33- to 44.5-fold higher than in SLITone® (4.00 µg/mL) and Wolwopharma® (2.97 µg/mL). The concentration of group 2 major allergen was also 8.9- to 10.5-fold higher in Staloral® (15.7 µg/mL) than in SLITone® (1.8 µg/mL) or Wolwopharma® (1.5 µg/mL). An ELISA inhibition study against HDM-specific IgE showed that the allergen potency of Staloral® reagent is 8.5-fold and 21-fold higher than that of SLITone® or Wolwopharma®, respectively. The differences between the maintenance dosages are further exaggerated by the differences in the recommended volumes of SLIT reagents.

Conclusions

The allergen potencies of commercially available HDM SLIT reagents are markedly different. Consensus regarding the optimal allergen concentration for SLIT reagents used to treat HDM respiratory allergies is needed.

Sublingual immunotherapy: recent advances

The practice of administering sublingual immunotherapy for respiratory allergy is gaining more and more diffusion worldwide as a consequence of the robust demonstration of clinical efficacy and safety provided by recent high-powered and well-designed studies, confirming for individual seasonal allergens the results of previous metanalyses in adult and pediatric populations. Preliminary evidence derives from recent rigorous trials on perennial allergens, like house dust mites, and specifically designed studies addressed the benefits on asthma. Emerging research suggests that SLIT may have a future role in other allergic conditions such as atopic dermatitis, food, latex and venom allergy. Efforts to develop a safer and more effective SLIT for inhalant allergens have led to the development of allergoids, recombinant allergens and formulations with adjuvants and substances targeting antigens to dendritic cells that possess a crucial role in initiating immune responses. The high degree of variation in the evaluation of clinical effects and immunological changes requires further studies to identify the candidate patients to SLIT and biomarkers of short and long term efficacy. Appropriate management strategies are urgently needed to overcome the barriers to SLIT compliance.

Sublingual immunotherapy: World Allergy Organization position paper 2013 update

We have prepared this document, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2013 Update", according to the evidence-based criteria, revising and updating chapters of the originally published paper, "Sublingual Immunotherapy: World Allergy Organization Position Paper 2009", available at http://www.waojournal.org. Namely, these comprise: "Mechanisms of sublingual immunotherapy;" "Clinical efficacy of sublingual immunotherapy" - reporting all the data of all controlled trials published after 2009; "Safety of sublingual immunotherapy" - with the recently published Grading System for adverse reactions; "Impact of sublingual immunotherapy on the natural history of respiratory allergy" - with the relevant evidences published since 2009; "Efficacy of SLIT in children" - with detailed analysis of all the studies; "Definition of SLIT patient selection" - reporting the criteria for eligibility to sublingual immunotherapy; "The future of immunotherapy in the community care setting"; "Methodology of clinical trials according to the current scientific and regulatory standards"; and "Guideline development: from evidence-based medicine to patients' views" - including the evolution of the methods to make clinical recommendations.Additionally, we have added new chapters to cover a few emerging crucial topics: "Practical aspects of schedules and dosages and counseling for adherence" - which is crucial in clinical practice for all treatments; "Perspectives and new approaches" - including recombinant allergens, adjuvants, modified allergens, and the concept of validity of the single products. Furthermore, "Raising public awareness about sublingual immunotherapy", as a need for our patients, and strategies to increase awareness of allergen immunotherapy (AIT) among patients, the medical community, all healthcare stakeholders, and public opinion, are also reported in detail.

Immunotherapy preparation guidelines, rules, and regulation

Allergen immunotherapy has been used to treat allergic diseases for more than 100 years. In the U.S., the preparation of diagnostic and therapeutic extracts requires the cooperation of the extract manufacturer, who provides the individual allergen concentrates, and the practicing physician who formulates, dilutes, and administers the final patient-specific treatment extract. The guidelines, rules, and regulations for these activities have been established and continue to be developed as progress is made. The molecular characterization and standardization of allergenic extracts has allowed for improvements in defining the potency of these products. In turn, these advances have led to improved dosing regimens and formulation practices. This review will describe in detail some of these interactions and will identify issues that require more attention.

A molecular diagnostic algorithm to guide pollen immunotherapy in southern Europe: towards component-resolved management of allergic diseases

Correct identification of the culprit allergen is an essential part of diagnosis and treatment in immunoglobulin E (IgE)-mediated allergic diseases. In recent years, molecular biology has made important advances facilitating such identification and overcoming some of the drawbacks of natural allergen extracts, which consist of mixtures of various proteins that may be allergenic or not, specific for the allergen source or widely distributed (panallergens). New technologies offer the opportunity for a more accurate component-resolved diagnosis, of benefit especially to polysensitized allergic patients. The basic elements of molecular diagnostics with potential relevance to immunotherapy prescription are reviewed here, with a focus on Southern European sensitization patterns to pollen allergens. We propose a basic algorithm regarding component-resolved diagnostic work-up for pollen allergen-specific immunotherapy candidates in Southern Europe; this and similar algorithms can form the basis of improved patient management, conceptually a 'Component-Resolved Allergy Management'.

Perception and practice of sublingual immunotherapy among practicing allergists in the United States: a follow-up survey

BACKGROUND

Limited information regarding current trends of sublingual immunotherapy (SLIT) use, perception, and prescribing patterns among allergists in the United States is available.

OBJECTIVE

To obtain information about current allergist perception and practice of SLIT compared with 2007.

METHODS

On behalf of the American College of Allergy, Asthma and Immunology (ACAAI) Immunotherapy and Diagnostics Committee, an electronic survey was sent to all practicing allergists of the ACAAI in August 2011.

RESULTS

Fifty-nine of 519 US respondents (11.4%) reported experience using SLIT compared with 45 of 766 (5.9%) in 2007 (P < .001). Lack of Food and Drug Administration (FDA) approval was the primary barrier in using SLIT in the United States among 469 of 520 respondents (90.2%), which was increased from 471 of 763 (61.7%) in 2007 (P < .001). Among US respondents, 344 of 516 (66.7%) believed that SLIT was safer than subcutaneous immunotherapy (SCIT) compared with 554 of 755 (73.4%) in 2007 (P < .01). In total, 22 of 51 SLIT users (43.1%) reported SLIT efficacy equal to or even greater than SCIT, which was similar to 21 of 38 (55.3%) reported in 2007 (P < .36).

CONCLUSION

Rates of SLIT use reported by US respondents have nearly doubled in the last 4 years, with 11.4% of US respondents reporting SLIT use. Because the greatest barrier to SLIT use in the United States is the lack of FDA approval, it is anticipated that once an FDA-approved product is available, there will be widespread use of SLIT in the United States. Practice guidelines, which include effective dosages and schedules, will be critical to the broad implementation of SLIT in the United States.

Differences in IgE mediated basophil degranulation induced by proteic fractions from whole flea body extract in patients with papular urticaria by flea bite and healthy controls

Background

Papular urticaria by flea bite (PUFB) is a chronic inflammatory disease in children. The aim of this study was to assess the functional activity of IgE to protein fractions from flea body extract, through basophil degranulation in PUFB patients and controls.

Methods

Basophil degranulation, measured by overexpression of CD63 surface molecules, was evaluated by flow cytometry in samples from patients and controls. Cell stimulation was performed with three fractions with different molecular weight from flea body extract using a Basotest® modified protocol. Mann–Whitney U-test was used for comparisons.

Results

Specific IgE from PUFB patients and healthy controls induced basophil degranulation to flea body extract with no significant differences between them (16.2 ± 3.1% vs 13.6 ± 2.8% p = 0.77). However, when flea extract was analyzed in fractions with proteins ranging different molecular weights, significant differences were observed on the response from patients compared with controls to <50 kD (14.9 ± 5.1% vs 9.7 ± 2.1% p = 0.0058) and 50–100 kD proteic fractions (8.3 ± 3.2% vs 2.8 ± 1.6% p = 0.0021).

Conclusion

In this study, was established that the differential response by IgE, in PUFB, depends from the molecular weight of the antigens contained in the flea extract. These antigens may be related to 30–35 kD proteins previously described as major allergens.

Survey on immunotherapy practice patterns: dose, dose adjustments, and duration

BACKGROUND

Practical issues dealing with the administration of allergen immunotherapy (AIT) by European and US allergists are not well known. Several concerns are only partially covered by guidelines.

OBJECTIVE

To survey AIT practice patterns among worldwide members of the American Academy of Allergy, Asthma and Immunology (AAAAI).

METHODS

A web-based survey was conducted among AAAAI members on dosing, dose adjustment after missed doses, and duration of AIT.

RESULTS

A total of 1,201 replies (24.7% response rate of which 10% of responses were from non-US and non-Canada members). A total of 57% to 65% of the US-Canadian dosing falls within the recommended Practice Parameter ranges (9.4%-19% too low). Dose adjustment after missed doses is based on time elapsed since the last administered dose by 77% of US-Canadian and 58% of non-US-Canadian allergists. Doses are reduced when a patient comes in more than 14 days for 5 weeks after the last administration and initial dosing restarted after more than 30 days for 12 weeks since last administration during the build-up or maintenance stage. After missing 1 to 3 doses, the dosing schedules were mostly followed (build-up phase: repeat last dose, reduce by 1 dose, reduce by 2doses; maintenance phase: reduce by 1 dose, reduce by 2 doses, reduce by 3 doses). AIT is prescribed for a median of 3 years by non-US-Canadian allergists but for a median of 5 years by 75% of US-Canadian allergists. Main reasons for continuing beyond 5 years were "after stopping, symptoms reappeared" or "patient afraid to relapse."

CONCLUSION

Many patients receive less than recommended doses. Two areas in which to plan further research are establishment of an optimal dose-adjustment plan for missed applications and exploration of the maximum appropriate duration of immunotherapy.

How's my dosing? A one-step, math-free guide for comparing your clinic's maintenance immunotherapy doses to current practice parameter recommendations

BACKGROUND

Immunotherapy dose recommendations for allergens specified in practice parameter updates have varied from version to version, and no convenient methods are available to incorporate dose changes or targets into maintenance vial formulations for patients.

OBJECTIVES

To compare the allergen immunotherapy dose recommendations published between 2003-2011, and to provide math-free dosing tables that translate dose targets for single or multiple extracts into maintenance vial compositions.

METHODS

Dose recommendations obtained from immunotherapy practice parameters published in 2003, 2007 and 2011, plus a worksheet created in 2004, were tabulated and compared. Conversion tables were created based on the fixed mathematical relationships between extract concentrate strengths and maintenance immunotherapy dose targets. Considerations of stock mixes, glycerin levels, and allergen compatibilities were applied using two examples of common extract formulations.

RESULTS

Changes to immunotherapy dose ranges for standardized extracts included adjustment of upper limits (short ragweed), lower limits (pasture grasses), or both (cat, dust mites, Bermuda grass). Dose ranges for non-standardized products have also been modified over time. Conversion tables specified the extract concentrate volumes or percentages required to deliver minimum, midrange and maximum recommended doses with 0.5 mL injection volumes.

CONCLUSIONS

These dosing guides, used in conjunction with cross-reactivity, compatibility and glycerin tolerance information, provide clinicians with a convenient and systematic method for determining the numbers and strengths of extracts that can be combined into treatment vials at various dose levels, and can facilitate optimization of maintenance immunotherapy mixtures for patients exhibiting a wide range of allergen sensitivities and specificities.