Epicutaneous/transcutaneous allergen-specific immunotherapy: rationale and clinical trials

Safety and efficacy of epicutaneous immunotherapy with DBV712 (peanut patch) in peanut allergy

INTRODUCTION

DBV712 250 µg (also referred to as Viaskin Peanut or peanut patch; Viaskin is a trademark of DBV Technologies) is an innovative approach to epicutaneous immunotherapy (EPIT). The patch-based technology system facilitates peanut protein (allergen) absorption into the intact non-vascularized epidermis to promote desensitization to peanut while limiting systemic allergen exposure.

AREAS COVERED

Efficacy and safety in children have been evaluated in four completed phase 3 studies. Overall, the results from these studies have demonstrated the peanut patch to be superior in desensitization compared with placebo and safe for daily use over multiple years.

EXPERT OPINION

These findings, as well as supportive evidence from phase 2 studies, confirm the potential for an effective treatment of peanut allergy in children. The purpose of this review is to summarize the safety and efficacy of the peanut patch in the treatment of peanut allergy.

Comparison of microneedles and adhesive-tape stripping in skin preparation for epicutaneous allergen delivery

BACKGROUND

Epicutaneous immunotherapy targets the network of dendritic cells in the epidermis. Allergen exposure of the dermal layers should be limited as these contain mast cells and blood vessels, which increases the risk for local and systemic allergic reactions.

METHODS

This intraindividually controlled trial included 20 subjects with birch pollen allergy. Three areas of the volar forearms were treated by repeated adhesive-tape stripping, single-prick lancet piercing and microneedle array application. Four 10-fold dilutions of allergen extract were applied to each area and the IgE-mediated immediate-phase reactions and cell-mediated eczema were assessed.

RESULTS

Allergen application after tape stripping led to an immediate-phase reaction in 2 subjects (10%) at the highest allergen concentration of 10 HEP/ml. Both prick needle and microneedle pretreatment resulted in immediate-phase reactions in all subjects (100%). The reactivity pattern, however, differed significantly: 95% of the reactions after pricking occurred at concentrations of ≤0.1 HEP/ml, whereas 50% of the reactions after microneedle preparation were noted at ≥1 HEP/ml. In 3 subjects (15%), eczema was observed on the microneedle-treated skin area. No serious adverse events occurred.

CONCLUSIONS

Microneedles enhance stratum corneum penetration when compared to tape stripping. However, they do not resolve the problem of mast cell-mediated local reactions, possibly due to diffusion into the dermis. The occurrence of eczema after the microneedle treatment suggests induction of dendritic cell-mediated T cell responses. Therefore, skin preparation with microneedles may be a promising method for epicutaneous allergen immunotherapy.

Is The Allergen Really Needed in Allergy Immunotherapy?

Immunotherapy for type I allergies is well established and is regarded to be the most efficient treatment option besides allergen avoidance. As of today, different forms of allergen preparations are used in this regard, as well as different routes of application. Virus-like particles (VLPs) represent a potent vaccine platform with proven immunogenicity and clinical efficacy. The addition of toll-like receptor ligands and/or depot-forming adjuvants further enhances activation of innate as well as adaptive immune responses. CpG motifs represent intensively investigated and potent direct stimulators of plasmacytoid dendritic cells and B cells, while T cell responses are enhanced indirectly through increased antigen presentation and cytokine release. This article will focus on the function of VLPs loaded with DNA rich in nonmethylated CG motifs (CpGs) and the clinical experience gained in the treatment of allergic rhinitis, demonstrating clinical efficacy also if administered without allergens. Several published studies have demonstrated a beneficial impact on allergic symptoms by treatment with CpG-loaded VLPs. Subcutaneous injection of VLPs loaded with CpGs was tested with or without the adjuvant alum in the presence or absence of an allergen. The results encourage further investigation of VLPs and CpG motifs in immunotherapy, either as a stand-alone product or as adjuvants for allergen-specific immunotherapy.

A comparison of immunotherapy delivery methods for allergen immunotherapy

BACKGROUND

Allergic diseases are among the most common diseases in humans. Besides allergen avoidance, allergen-specific immunotherapy is the only causative treatment option. During recent years, many innovations of this therapy have emerged.

METHODS

Selective literature research in Medline and PubMed, under the inclusion of national and international guidelines and Cochrane meta analyses.

RESULTS

In several meta-analyses, the clinical efficacy of subcutaneous immunotherapy (SCIT) has been largely demonstrated. Recently, major research activities in mucosal immunotherapies focused on the sublingual application route. There are well-documented clinical data on the efficacy and safety of this form of immunotherapy. New application routes as well as new immune-modifying agents such as virus-like particles or CpG-motifs have also been investigated.

CONCLUSION

SIT is accepted to be the only causative treatment option for allergies. New application routes and new immune-modifying agents will allow for different delivery methods in the future.

Allergen immunotherapy: routes, safety, efficacy, and mode of action

Allergic rhinitis, allergic conjunctivitis, and allergic asthma have been steadily increasing in prevalence in recent years. These allergic diseases have a major impact on quality of life and are a major economic burden in the US. Although allergen avoidance and pharmacotherapy are currently the mainstays of therapy, they are not always successful in treating patients' symptoms effectively. If a patient fails allergen avoidance and medical therapy, immunotherapy may be indicated. Furthermore, immunotherapy is the only therapy that may change the course of the disease and induce long-term remission. Though subcutaneous administration has been the standard route for immunotherapy for many decades, there are several other routes of administration that have been and are currently being studied. The goal of utilizing alternative routes of immunotherapy is to improve safety without decreasing the efficacy of treatment. This paper will review the novel routes of immunotherapy, including sublingual, oral, local nasal, epicutaneous, and intralymphatic.

Therapeutic potential of semi-mature dendritic cells for tolerance induction

Dendritic cells (DCs) are major players in the control of adaptive tolerance and immunity. Therefore, their specific generation and adoptive transfer into patients or their in vivo targeting is attractive for clinical applications. While injections of mature immunogenic DCs are tested in clinical trials, tolerogenic DCs still are awaiting this step. Besides the tolerogenic potential of immature DCs, also semi-mature DCs can show tolerogenic activity but both types also bear unfavorable features. Optimal tolerogenic DCs, their molecular tool bar, and their use for specific diseases still have to be defined. Here, the usefulness of in vitro generated and adoptively transferred semi-mature DCs for tolerance induction is outlined. The in vivo targeting of semi-mature DCs as represented by steady state migratory DCs are discussed for treatment of autoimmune diseases and allergies. First clinical trials with transcutaneous allergen application may point to their therapeutic use in the future.

Induction of tolerance via the sublingual route: mechanisms and applications

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