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

Utility of silver birch and house dust mite extracts derived from licensed sublingual tablets for nasal allergen challenge

BACKGROUND

Nasal allergen challenge (NAC) is used to investigate the effects of allergen exposure and assess treatment efficacy in allergic rhinitis (AR). This study aims to establish dose-responses to NAC using licensed silver birch (SB) pollen and house dust mite (HDM) sublingual tablets as sources of the allergen extracts in participants with AR.

METHODS

Sixteen volunteers with HDM-induced perennial AR and 15 volunteers with SB pollen-induced seasonal rhinitis underwent a graded up-dosing NAC with extracts derived from HDM allergen (Acarizax®) and SB (Itulazax®) tablets, respectively. Total nasal symptom score (TNSS, range 0-12) and peak nasal inspiratory flow (PNIF) were recorded before, at 10 min and at the end of the NAC. The dose of each allergen that provoked a TNSS of at least 7 ("provoking dose 7") in most allergic participants was identified. NACs using the "provoking dose 7" were performed on 5 non-allergic individuals to test for irritant effects. The "provoking dose 7" of HDM extract was used in a subgroup of two SB allergic, non-HDM allergic, volunteers, and vice versa for SB extract, to test for allergen specificity of the responses.

RESULTS

Most patients experienced a TNSS of at least 7/12 at a median concentration of 1500 AU/mL for both SB pollen and HDM. The average decline in PNIF at this dose was 63.15% for SB and 63.99% for HDM. NACs using the 1500 AU/mL concentrations were performed on 5 non-allergic individuals with no symptomatic or PNIF response. 1500 AU/mL of HDM extract produced no symptoms in SB allergics nor 1500 AU/mL SB extract in HDM allergics.

CONCLUSION

For both SB and HDM extracts, the optimal allergen dose for NAC to cause a moderate-severity response ("provoking dose 7/12") was 1500 AU/mL. Licensed sublingual allergen tablets provide a readily available and inexpensive source of SB and HDM extracts for use in future interventional studies in AR.

SQ sublingual immunotherapy tablets for children with allergic rhinitis: A review of phase three trials

AIM

To provide paediatricians with a summary of efficacy and safety of SQ sublingual immunotherapy (SLIT) tablets from phase three, randomised, double-blind, placebo-controlled trials in children and adolescents with allergic rhinitis or rhinoconjunctivitis, with and without asthma.

METHODS

PubMed searches were conducted and unpublished data were included if necessary.

RESULTS

Of the 93 publications, 12 were identified reporting 10 trials. One trial was excluded as paediatric-specific efficacy data were unavailable. The nine eligible trials evaluated grass, house dust mite, ragweed and tree SLIT tablets. Consistent reductions in allergic rhinitis or rhinoconjunctivitis symptoms and medication use were observed with SQ SLIT tablets versus placebo. In a five-year trial, sustained reduction of allergic rhinoconjunctivitis symptoms, asthma symptoms and medication use were observed with SQ grass SLIT tablet versus placebo. The number-needed-to-treat to prevent asthma symptoms and medication use in one additional child during follow-up was lowest in younger children. SQ SLIT tablets were generally well tolerated across trials.

CONCLUSION

Evidence supports use of SQ SLIT tablets in children and adolescents with allergic rhinitis or rhinoconjunctivitis, with and without asthma. Long-term data demonstrate disease-modifying effects of SQ grass SLIT tablet and suggest the clinical relevance of initiating allergy immunotherapy earlier in the disease course.

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.

Japanese Cedar Pollen Allergens in Japan

Pollen from members of the Cupressaceae tree family is one of the most important causes of allergic disease in the world. Cryptomeria japonica (Japanese cedar) and Chamaecyparis obtusa (Japanese cypress) are Japan's most common tree species. The pollen dispersal season is mainly from February to May. The major allergens of Japanese cedar and Japanese cypress exhibit high amino acid sequence similarity due to the phylogenetic relationship between the two species. An epidemiological study has shown that the prevalence of Japanese cedar pollinosis is approximately 40%. Younger children (5 to 9 years old) showed a high prevalence of Japanese cedar pollinosis as 30% in 2019, indicating that season pollinosis is getting worse. Pharmacotherapy is the most common treatment for pollinosis induced by Japanese cedar and Japanese cypress. Patients' satisfaction with pharmacotherapy is low due to insufficient experienced effect and daytime somnolence. Unlike pharmacotherapy, allergy immunotherapy (AIT) addresses the basic immunological mechanisms of allergic disease and activates protective allergen-reactive pathways of the immune system. AIT is now recognized as the only treatment option with the potential to provide long-term post-treatment benefits and alter the natural course of the allergic disease, including Japanese cedar pollinosis.

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.

Allergen Release Profiles of Fast-Dissolving Freeze-Dried Orodispersible Sublingual Allergy Immunotherapy Tablets

Background

Sublingual allergy immunotherapy tablets (SLIT-tablets) provide a well-tolerated and clinically efficacious treatment for allergic disease such as allergic rhinitis and allergic asthma. In SLIT, uptake of allergen by immune-competent cells in the oral mucosa activates the immune system and leads to tolerance toward the sensitizing allergen. The ability to deliver the full allergen content into solution within the recommended sublingual holding time is therefore an essential quality of SLIT-tablets that must be supported by the tablet formulation for all relevant allergen sources. SLIT-tablets based on a fast-dissolving orodispersible freeze-dried formulation (Zydis) are currently available for 5 of the most prevalent allergens: tree (birch and related species from the birch-homologous group), grass, ragweed, Japanese cedar, and house dust mite.

Objectives

The purpose of this study was to examine the allergen release properties of three freeze-dried SLIT-tablets containing tree, ragweed, and Japanese cedar extracts, respectively. The correlation between SLIT-tablet allergen release and the level of allergen-specific T-cell activation was examined for the tree SLIT-tablet.

Methods

Allergen release kinetics and tablet disintegration times for the 3 freeze-dried SLIT-tablets were examined. For all 3 tablets, the magnitude of solubilized major allergen relative to time in solution was compared to external controls to achieve a measure of the total allergen release. Additional assessments of allergen release occurring after the initial timepoint (15 or 30 seconds in solution) were done independently of external controls by linear regression analyses. For the tree SLIT-tablet, the immunological potency of the released major allergen was assessed at each experimental timepoint by a Bet v-specific T-cell activation assay.

Results

All 3 SLIT-tablets disintegrated within 1 second after contact with assay buffer without any detectible residue. Complete release of major allergens (Bet v 1, Amb a 1, and Cry j 1, respectively) was seen at the earliest experimental time points (15 or 30 seconds). For the tree SLIT-tablet, full T-cell activation was achieved at 30 seconds (earliest experimental time point).

Conclusions

The freeze-dried SLIT-tablet formulation consistently provides rapid and complete release of allergen from a wide range of species in a standardized in vitro assay. Full release of the SLIT-tablet allergen content within the sublingual holding time is a prerequisite for maximal exposure of allergens to the sublingual mucosa immune system. The freeze-dried SLIT-tablet formulation examined here supports short sublingual holding times and furthermore offers a convenient administration form of allergy immunotherapy.

The Use of Megamolecular Polysaccharide Sacran in Food and Biomedical Applications

Natural polymer is a frequently used polymer in various food applications and pharmaceutical formulations due to its benefits and its biocompatibility compared to synthetic polymers. One of the natural polymer groups (i.e., polysaccharide) does not only function as an additive in pharmaceutical preparations, but also as an active ingredient with pharmacological effects. In addition, several natural polymers offer potential distinct applications in gene delivery and genetic engineering. However, some of these polymers have drawbacks, such as their lack of water retention and elasticity. Sacran, one of the high-molecular-weight natural polysaccharides (megamolecular polysaccharides) derived from Aphanothece sacrum (A. sacrum), has good water retention and elasticity. Historically, sacran has been used as a dietary food. Moreover, sacran can be applied in biomedical fields as an active material, excipient, and genetic engineering material. This article discusses the characteristics, extraction, isolation procedures, and the use of sacran in food and biomedical applications.

State of the Art: Development of a Sublingual Allergy Immunotherapy Tablet for Allergic Rhinitis in Japan

Allergic rhinitis (AR) caused by house dust mite (HDM) and Japanese cedar pollen (JCP) represents a significant, expanding health problem in Japan. Allergic symptoms often have a severe impact on the QOL such as sleep disturbance and reduced school and work performance. In addition to the classical symptoms, AR is known to be a risk factor for the development of allergic asthma, a potentially life-threatening condition. Allergy immunotherapy (AIT) is a well-documented, safe, effective treatment option for respiratory allergic disease. It has been demonstrated that AIT can provide relief from clinical symptoms and that AIT has the potential to provide long-term post-treatment effect. Although the mechanism of AIT is not fully understood, it can actively modulate protective allergen-reactive pathways of the immune system and alter the natural course of disease. Unlike pharmacotherapy, AIT addresses the basic immunological mechanisms that are responsible for the development and persistence of allergic conditions. Currently two main routes of AIT administration are commonly available, subcutaneous immunotherapy (SCIT) and sublingual immunotherapy (SLIT). Both SCIT and SLIT are clinically effective, and SLIT is particularly well tolerated, with a lower risk of systemic allergic reactions compared with SCIT. To date, SLIT tablets have been developed for a range of different allergies including HDM and JCP and are the best-documented AIT treatment form. Here we introduce the current status of development of a SLIT tablet in Japan for AR, examine the clinical aspects and mechanism of action of AIT, and discuss the future directions of SLIT.

Compromising between European and US allergen immunotherapy schools: Discussions from GUIMIT, the Mexican immunotherapy guidelines

Background

Allergen immunotherapy (AIT) has a longstanding history and still remains the only disease-changing treatment for allergic rhinitis and asthma. Over the years 2 different schools have developed their strategies: the United States (US) and the European. Allergen extracts available in these regions are adapted to local practice. In other parts of the world, extracts from both regions and local ones are commercialized, as in Mexico. Here, local experts developed a national AIT guideline (GUIMIT 2019) searching for compromises between both schools.

Methods

Using ADAPTE methodology for transculturizing guidelines and AGREE-II for evaluating guideline quality, GUIMIT selected 3 high-quality Main Reference Guidelines (MRGs): the European Academy of Allergy, Asthma and Immunology (EAACI) guideines, the S2k guideline of various German-speaking medical societies (2014), and the US Practice Parameters on Allergen Immunotherapy 2011. We formulated clinical questions and based responses on the fused evidence available in the MRGs, combined with local possibilities, patient's preference, and costs. We came across several issues on which the MRGs disagreed. These are presented here along with arguments of GUIMIT members to resolve them. GUIMIT (for a complete English version, Supplementary data) concluded the following.

Results

Related to the diagnosis of IgE-mediated respiratory allergy, apart from skin prick testing complementary tests (challenges, in vitro testing and molecular such as species-specific allergens) might be useful in selected cases to inform AIT composition. AIT is indicated in allergic rhinitis and suggested in allergic asthma (once controlled) and IgE-mediated atopic dermatitis. Concerning the correct subcutaneous AIT dose for compounding vials according to the US school: dosing tables and formula are given; up to 4 non-related allergens can be mixed, refraining from mixing high with low protease extracts. When using European extracts: the manufacturer's indications should be followed; in multi-allergic patients 2 simultaneous injections can be given (100% consensus); mixing is discouraged. In Mexico only allergoid tablets are available; based on doses used in all sublingual immunotherapy (SLIT) publications referenced in MRGs, GUIMIT suggests a probable effective dose related to subcutaneous immunotherapy (SCIT) might be: 50-200% of the monthly SCIT dose given daily, maximum mixing 4 allergens. Also, a table with practical suggestions on non-evidence-existing issues, developed with a simplified Delphi method, is added. Finally, dissemination and implementation of guidelines is briefly discussed, explaining how we used online tools for this in Mexico.

Conclusions

Countries where European and American AIT extracts are available should adjust AIT according to which school is followed.

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.

Safety of Timothy Grass Sublingual Immunotherapy Tablet in Children: Pooled Analyses of Clinical Trials

BACKGROUND

Timothy grass sublingual immunotherapy (SLIT) tablets are indicated for children with allergic rhinitis with or without conjunctivitis.

OBJECTIVE

To use pooled analyses to assess the short- and long-term tolerability and safety of timothy grass SLIT-tablet in children.

METHODS

Data from 9 double-blinded, randomized European or North American trials that included children with allergic rhinitis with or without conjunctivitis treated up to 3 years with once-daily timothy grass SLIT-tablet or placebo were pooled.

RESULTS

In all, 1818 (timothy grass SLIT-tablet, n = 923; placebo, n = 895) subjects were included in the analysis. The frequency of treatment-emergent adverse events (AEs) was 86% in the SLIT-tablet group and 83% in the placebo group, and the frequency of treatment-related AEs (TRAEs) was 59% and 23%, respectively. Most (98%) TRAEs were mild to moderate in severity. The 2 most common TRAEs with SLIT-tablet were oral pruritus (33%) and throat irritation (19%), which had a median onset of 1 day and recurrence of 14.5 and 5 days, respectively. In all, 8% of subjects in the SLIT-tablet group and 2% in the placebo group discontinued because of AEs. There were 7 serious AEs assessed as related to SLIT-tablet, 1 systemic allergic reaction (severe with a drop in blood pressure), 3 epinephrine administrations, no eosinophilic esophagitis events, and no serious airway obstructions. The safety profile was similar in subjects across geographic regions and with and without asthma.

CONCLUSIONS

Pooled data indicate that short- and long-term timothy grass SLIT-tablet is well tolerated in children, regardless of geographic region. AEs were generally local, mild, and transient allergic reactions.

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.

The Effective Allergenic Reactivity of House Dust Mite Sublingual Immunotherapy Tablets Is Determined by Tablet Formulation

House dust mite (HDM) sublingual immunotherapy (SLIT) in the form of SLIT-tablets is now an established treatment option for HDM allergy and HDM-induced allergic asthma. In SLIT-tablet immunotherapy allergen extracts are formulated as dry tablets and administered under the tongue where it must be solubilized in saliva in order to be able to interact with the immune system of the sublingual mucosa. Solubilization of the extract must occur within a short time span of about one minute after administration, determined by the sublingual holding time recommended by the manufacturer. Currently, two types of HDM SLIT-tablets are available. Both tablet types contain natural HDM extracts from two common HDM species as the active ingredient, but differ with regard to formulation as one tablet type is based on a freeze-dried tablet formulation while the other is based on a compressed formulation. HDM extracts contain a number of major and minor allergens, which in combination provide the allergenic activity that drives the immunological response and in turn the clinical efficacy of the tablets. Here, a biologically relevant human immunoglobulin E (IgE)-based assay is used to compare the ability of the two HDM SLIT-tablet types to deliver HDM allergenic reactivity from the dry tablet into soluble form. The experiments demonstrate that the freeze-dried formulation delivers HDM allergenic activity into solution faster and more efficiently than the compressed formulation.

SQ house dust mite sublingual immunotherapy for the treatment of adults with house dust mite-induced allergic rhinitis

Introduction: Allergic rhinitis (AR) is one of the most common chronic conditions affecting both children and adults. The house dust mites (HDM) account for a substantial part of the overall sources of allergens. In patients where allergen avoidance and symptom-relieving pharmacotherapy do not provide adequate disease control, specific allergen immunotherapy (AIT) is indicated. While subcutaneous injection (SCIT) is considered as a time-consuming and invasive treatment regimen, sublingual allergy immunotherapy (SLIT) appears as more convenient treatment strategy.Areas covered: This Drug Profile reviews the clinical data behind the development of the SQ HDM SLIT-tablet, including both the early studies and the pivotal studies, which formed the basis for regulatory approval in Europe, Japan, and the U.S.Expert opinion: The clinical trials behind the development of the SQ HDM-SLIT have demonstrated that the tablet provides a safe, well-tolerated and robust efficacy in the treatment of HDM-induced allergic rhinoconjunctivitis. Further, studies show that the SQ HDM SLIT-tablet is a cost-effective treatment option compared with SCIT.

Treatment duration-dependent efficacy of Japanese cedar pollen sublingual immunotherapy: Evaluation of a phase II/III trial over three pollen dispersal seasons

BACKGROUND

We conducted a randomized, placebo-controlled, double-blind clinical trial to investigate the optimal dose and long-term efficacy and safety of Japanese cedar (JC) pollen tablets for SLIT (JapicCTI-142579). Here, we report details of the effects of the JC pollen SLIT tablet on rhinitis and conjunctivitis symptoms over three pollen dispersal seasons.

METHODS

A total of 1042 JC pollinosis patients (aged 5-64 years) were randomized to receive tablets containing placebo (P), 2000, 5000, or 10,000 Japanese allergy units (JAU) of JC pollen for 15 months to identify an optimal dose. Patients receiving P (n = 240) and the optimal dose (5000 JAU; A, n = 236) were then randomized to receive P or A for an additional 18 months (AA, AP, PA, and PP groups, allocation ratio 2:1:1:2). Nasal and ocular symptoms, rescue medication use, and quality of life (QOL) were assessed on quantitative scales.

RESULTS

In the second and third seasons, the AA, AP, and PA groups exhibited significantly better improvements in nasal, ocular, and medication scores compared with the PP group in the order AA > AP > PA > PP during the second season and AA > PA > AP > PP during the third season. Rescue medication use and QOL scores were also significantly better in the AA, AP, and PA groups compared with the PP group.

CONCLUSIONS

The JC pollen SLIT tablet relieved nasal and ocular symptoms and medication use and improved QOL in a treatment duration-dependent manner. Continuous dosing regimens appear to enhance the efficacy of the drug.

Efficacy and Safety of HDM SLIT Tablet in Japanese Adults with Allergic Asthma

BACKGROUND

The standardized quality (SQ) house dust mite (HDM) sublingual immunotherapy (SLIT) tablet has demonstrated efficacy and safety for allergic asthma (AA) in European trials.

OBJECTIVE

To evaluate the efficacy and safety of SQ HDM SLIT tablet treatment for up to 19 months in Japanese adults with AA.

METHODS

In this randomized, double-blind, placebo-controlled trial, patients aged 18 to 64 years with AA were randomly assigned (1:1:1) to SQ HDM SLIT doses of 10,000 or 20,000 Japanese Allergy Unit or placebo. Subjects had Asthma Control Questionnaire score of 1.0 to 1.5 and daily inhaled corticosteroid use of 200 to 400 μg of fluticasone propionate at randomization. The primary end point was the time from randomization to the first asthma exacerbation as the inhaled corticosteroid dose was being reduced.

RESULTS

Of the 826 randomized subjects, 693 (84%) completed the trial. No statistically significant differences between the active groups and the placebo group were observed for the primary or any other efficacy end points. However, post hoc analysis indicated a significant difference between the 20,000 Japanese Allergy Unit and placebo groups among subjects who used a short-acting β₂-agonist during the baseline period (hazard ratio, 0.70; 95% CI, 0.48-1.00; P = .04997). No deaths or anaphylactic reactions were reported. Most adverse events were mild to moderate in severity.

CONCLUSIONS

The trial demonstrated a favorable safety profile of the SQ HDM SLIT tablet in Japanese adult patients with AA. The treatment appeared to be efficacious in patients requiring rescue medication (ie, short-acting β₂-agonist) at baseline in the efficacy assessment using asthma exacerbation during inhaled corticosteroid reduction (JapicCTI number 121847).

Clinical efficacy of sublingual immunotherapy tablets for allergic rhinitis is unlikely to be derived from in vitro allergen-release data

Introduction: Allergen bioavailability underpins the efficacy and safety of SLIT tablets. Three product-related factors are likely to influence this: tablet potency, formulation and sublingual holding time. Areas covered: Tablet formulation determines the rate and extent of solubilized allergen release. Using validated in vitro dissolution assays, the two licensed grass pollen SLIT tablets are shown to release ≥85% of their total allergenic activity within several minutes. Sublingual holding time affects the contact duration between solubilized allergens and sublingual tissue. Maximal uptake of allergens by sublingual tissue requires ~5 minutes, with little uptake occurring within the first minute. A higher potency tablet with longer sublingual holding time would provide higher bioavailability, while faster rates of allergen release in vitro are unlikely to translate to a greater increase in bioavailability. Differences in dissolution times cannot serve as a surrogate of in vivo bioavailability, and are not related to differences in efficacy at the marketed tablet dosages. Rapid in vitro dissolution is likely not a key requirement for inducing a potent immune response. Expert opinion: In vitro dissolution cannot predict the clinical efficacy of SLIT tablets but could be important in immune tolerance and safety. In addition, a discontinuous administration regimen may have benefits for adherence and cost without compromising efficacy.

GRAZAX®: a sublingual immunotherapy vaccine for Hay fever treatment: from concept to commercialization

Allergen immunotherapy has been used for more than 100 y, but only recently underlying immunological mechanisms have started to be understood. New Allergy vaccines are now considered to be full pharmaceutical products, that should comply with general as well as specific pharmaceutical legal framework. GRAZAX® is the first global allergy vaccine developed in compliance with the new legal environment and is thus a reference for developing new allergy vaccines. Here, we provide a rationale description of GRAZAX®, providing a sequential description of its pharmaceutical and clinical development. With more than 25 clinical trials, involving more than 8000 patients, including as well three 5-y prospective clinical trials, GRAZAX® is a key product to understand the unique position of allergen-specific immunotherapy as a disease-modifying intervention.

Persistent regulatory T-cell response 2 years after 3 years of grass tablet SLIT: Links to reduced eosinophil counts, sIgE levels, and clinical benefit

Background

In the first 2 years of grass tablet sublingual immunotherapy treatment, we have previously demonstrated a progressive development of a regulatory T‐cell response, which was preceded by an early decrease in the frequency of both IL‐4+ cells and sIgE levels. A progressive increase in sIgG₄ levels and FAB blockage were also found.

Methods

By monitoring immunological kinetics during 3 years of active treatment + 2 years of follow‐up, we aimed to identify key immunological parameters that could explain sustained clinical benefit of grass tablet sublingual immunotherapy.

Results

Thirty patients completed the 5‐year clinical trial protocol. Although individual responses were heterogeneous, reduction in both sIgE and circulating IL‐4+ cells compared to the initial 1‐ to 4‐month peak was maintained throughout the 3‐year treatment period and for 2 years after discontinuation. Meanwhile, after a 2‐year increase in sIgG4, the levels were stabilized during the third year and decreased post‐therapy. FAB inhibition remained significantly inhibited throughout the study compared to preimmunotherapy in 83% of patients. A sustained regulatory T‐cell response, after IT cessation, occurs in two‐thirds of the patients. There was a statistical association between this regulatory response, the maintenance of lower eosinophil counts during grass pollen seasons, and sIgE titers lower than before immunotherapy treatment, and the latter were significantly associated with clinical response.

Conclusion

Our results suggest that the immunological mechanisms underlying the sustained response after 2 years of cessation of immunotherapy (3‐year treatment period) are linked to the acquisition and maintenance of a regulatory T‐cell response.

The SQ tree SLIT-tablet is highly effective and well tolerated: Results from a randomized, double-blind, placebo-controlled phase III trial

BACKGROUND

The SQ tree sublingual immunotherapy (SLIT)-tablet (ALK-Abelló, Hørsholm, Denmark) is developed for treatment of tree pollen-induced allergic rhinoconjunctivitis (ARC).

OBJECTIVE

The aim of this pivotal phase III trial was to demonstrate the efficacy and safety of the SQ tree SLIT-tablet.

METHODS

This was a randomized, double-blind, placebo-controlled trial with 634 subjects (12-65 years) with moderate-to-severe ARC despite use of symptom-relieving medication. Eligible subjects were randomized 1:1 to active or placebo treatment. The primary end point was the average daily ARC total combined score (TCS) during the birch pollen season (BPS) analyzed for subjects with diary data during the BPS. Secondary end points included average daily symptom scores (DSS) during the BPS, average TCS and DSS during the tree pollen season (TPS), and average daily medication scores (DMS) in the BPS and TPS.

RESULTS

The primary and key secondary end points demonstrated statistically significant and clinically relevant effects of the SQ tree SLIT-tablet compared with placebo. For the BPS, absolute (relative) differences from placebo were 3.02 (40%) for TCS, 1.32 (37%) for DSS, and 1.58 (49%) for DMS (all P < .0001). For the TPS, absolute (relative) differences from placebo were 2.27 (37%) for TCS, 0.99 (33%) for DSS, and 1.20 (47%) for DMS (all P < .0001). Treatment was well tolerated. The most frequently reported treatment-related adverse events were mild or moderate local reactions related to sublingual administration.

CONCLUSION

The trial demonstrated the efficacy and safety of the SQ tree SLIT-tablet compared with placebo during the BPS and TPS in adolescents and adults with birch pollen-induced ARC (EudraCT 2015-004821-15).

Efficacy and safety of SQ house dust mite sublingual immunotherapy-tablet in Japanese children

BACKGROUND

The SQ house dust mite (HDM) sublingual immunotherapy (SLIT)-tablet (TO-203, Torii, Japan/ALK, Denmark) treatment has been effective against respiratory allergic diseases in patients aged ≥12 years during European, Japanese, and North American trials. This trial was conducted to investigate the efficacy and safety of this treatment in Japanese children (5-17 years) with moderate-to-severe HDM allergic rhinitis (AR).

METHODS

In this randomized, double-blind, placebo-controlled trial, 458 Japanese children were randomly assigned to a daily SQ HDM SLIT-tablet [10 000 Japanese Allergy Unit (JAU), equivalent to 6 SQ-HDM in Europe and the US] or placebo (1:1) treatment for 1 year. Inclusion required an AR symptom score of ≥7 on at least 7 days during a 14-day run-in period while symptomatic treatment was withdrawn. The primary endpoint was the total combined rhinitis score (TCRS) comprising AR symptom and medication scores during the last 8 weeks of the treatment period.

RESULTS

The analysis of primary endpoint demonstrated statistically significant absolute reduction in TCRS of 1.22 with a relative difference of 23% (95% confidence interval, 14% to 31%) in the 10 000 JAU compared with placebo. Predefined stratified analyses revealed the same degree of efficacy of 1.11 (P = 0.002), 21% (8% to 32%) and 1.36 (P = 0.001), 26% (11% to 38%), respectively, in pediatric (5-11 years) and adolescent subjects (12-17 years). The treatment was well tolerated by both pediatric and adolescent subjects.

CONCLUSION

This trial, for the first time, demonstrated the efficacy and safety of the HDM SLIT-tablet in pediatric patients with moderate-to-severe HDM AR (JapicCTI-152953).

Safety profile of the SQ house dust mite sublingual immunotherapy-tablet in Japanese adult patients with house dust mite-induced allergic asthma: a randomized, double-blind, placebo-controlled phase I study

Objective: The SQ house dust mite (HDM) sublingual immunotherapy (SLIT)-tablet has demonstrated effective treatment of HDM-induced allergic asthma in patients 18 years or older in European trials. This study investigated its safety and immunology profile in Japanese adult patients with mild-to-moderate HDM-induced allergic asthma. Methods: In this randomized, double-blind, placebo-controlled study, 48 Japanese patients were randomly assigned to a daily treatment of SQ HDM SLIT-tablet or placebo (3:1) for 14 d with or without an up-dosing regimen. Active groups comprised 5000, 10,000 or 20,000 Japanese Allergy Unit (JAU) for 14 d, and the up-dosing group comprised 5,000 JAU in day 1-3, 10,000 JAU in day 4-7 and 20,000 JAU in day 8-14. Results: No marked differences were observed in the incidence rate of adverse events (AEs) and their severity among active groups. The five most common investigational medicinal product (IMP)-related AEs were local events at the application site observed within 30 min after the intake of the SQ HDM SLIT-tablet. Although most events recovered within 1 h, mouth edema indicated a different profile of duration with more than 25% of the events lasting for more than 1 h. Conclusions: The SQ HDM SLIT-tablet of up to 20,000 JAU was well tolerated, and safety profile was acceptable for Japanese subjects with HDM-induced allergic asthma.

Allergen Extracts for In Vivo Diagnosis and Treatment of Allergy: Is There a Future?

Today, in vivo allergy diagnosis and allergen-specific immunotherapy (AIT) are still based on allergen extracts obtained from natural allergen sources. Several studies analyzing the composition of natural allergen extracts have shown severe problems regarding their quality such as the presence of undefined nonallergenic materials, contaminants as well as high variabilities regarding contents and biological activity of individual allergens. Despite the increasing availability of sophisticated analytical technologies, these problems cannot be overcome because they are inherent to allergen sources and methods of extract production. For in vitro allergy diagnosis problems related to natural allergen extracts have been largely overcome by the implementation of recombinant allergen molecules that are defined regarding purity and biological activity. However, no such advances have been made for allergen preparations to be used in vivo for diagnosis and therapy. No clinical studies have been performed for allergen extracts available for in vivo allergy diagnosis that document safety, sensitivity, and specificity of the products. Only for very few therapeutic allergen extracts state-of-the-art clinical studies have been performed that provide evidence for safety and efficacy. In this article, we discuss problems related to the inconsistent quality of products based on natural allergen extracts and share our observations that most of the products available for in vivo diagnosis and AIT do not meet the international standards for medicinal products. We argue that a replacement of natural allergen extracts by defined recombinantly produced allergen molecules and/or mixtures thereof may be the only way to guarantee the supply of clinicians with state-of-the-art medicinal products for in vivo diagnosis and treatment of allergic patients in the future.

The efficacy of sublingual immunotherapy for allergic diseases in Asia

Sublingual immunotherapy (SLIT) has been proven to be safe and effective from an abundance of Western literature, but data from Asia is less complete. This review aims to examine the basic science, safety and efficacy of SLIT in Asian patients, and to determine future research needs in Asia. We performed a literature search on PUBMED, Scopus, and Cochrane Library database for articles on SLIT originating from Asian countries through Nov 2017. There were 18 randomized, double-blind, placebo-controlled trials, of which 9 involved solely paediatric subjects. Overall, sublingual immunotherapy is safe and is efficacious in Asian populations in allergic rhinitis (AR) and asthma. House dust-mite SLIT is effective in both mono- and polysensitized AR patients. Efficacy of SLIT is comparable to subcutaneous immunotherapy. Data on long term efficacy is lacking. A disproportionate majority of research originates from China and Japan, reflecting an asymmetry of access to SLIT within Asia. Significant disparities exist in the development of the allergy speciality, prescription patterns of SLIT, and pharmacological potencies of different SLIT products within and between Asian nations. We conclude that current available evidence suggests SLIT is efficacious in Asians but data quality of evidence is hampered by non-placebo controlled studies with methodological limitations. More data is needed in South and Southeast Asian populations. Future efforts may be directed towards improving access to SLIT in developing countries, standardization of SLIT dosage, and evaluating long term clinical outcomes.

Current status of sublingual immunotherapy for allergic rhinitis in Japan

Japanese cedar pollen (JCP) and house dust mite (HDM) are two major allergens that cause allergic rhinitis (AR) in Japan and the prevalence of AR is increasing. Pharmacothearpy is a commonly used treatment, but the level of patient satisfaction is very low. Allergen immunotherapy (AIT) is the only therapeutic modality that provides not only symptom relief but also quality of life improvement that leads to a high rate of satisfaction. In particular, sublingual immunotherapy (SLIT) is a safe and effective treatment for AR. Here we introduce a large-scale double-blind, placebo-controlled trial of SLIT in Japanese patients using JCP droplets or HDM tablets conducted in Japan. The immediate future of SLIT in Japan is also discussed.

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.