Immunotherapeutic targeting of allergic disease

Virus-like particles (VLP) in prophylaxis and immunotherapy of allergic diseases

BACKGROUND

Apart from active allergen avoidance, immunotherapy is regarded as the most effective form of treatment available for type I allergies. Such treatments involve the administration of allergen preparations in various forms and by various routes. Virus-like particles (VLPs) offer a very effective platform for immunization with the allergen and are characterized by high immunogenicity, low allergenicity and high clinical efficacy. Formulations that include Toll-like receptor ligands, T cell stimulatory epitopes and/or depot-forming adjuvants appear to enhance activation of the relevant immune cells. Short nucleotide sequences including CpG motifs have also been intensively explored as potent stimulators of dendritic cells and B cells.

METHODS

The present paper is based on a systematic literature search in PubMed and MEDLINE, and focuses on the pertinent immunological processes and on clinical data relating to use of VLPs and CpG motifs for the treatment of allergic rhinitis (AR).

RESULTS

Many published studies have reported positive clinical results following administration of VLPs, either alone or in combination with CpG motifs and, in some cases, even in the absence of the allergen-specific allergen.

CONCLUSIONS

These results indicate that VLPs modulate immune responses in ways which underline their exceptional promise as a platform for the immunotherapy of allergic disorders. However, clinical evaluations remain limited, and further large-scale and longer-term studies will be necessary to substantiate the efficacy and safety of these novel therapies.

Immunotherapy of type-1 allergies with virus-like particles and CpG-motifs

Immunotherapy of type-I-allergies is regarded as the most efficient treatment option besides allergen avoidance. Different forms of allergen preparations are used as well as different routes of application. Virus-like particles 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 immune cell activation. This article will focus on the function of virus-like particles loaded with DNA rich in CpG-motifs and discuss clinical experience in treatment of allergic rhinitis. Evidence will be presented that clinically effective treatment can be obtained even in the absence of allergens. Results encourage further investigation of virus-like particles and CpG-motifs in immunotherapy, either as a stand alone product, or as adjuvants for allergen-specific immunotherapy.

Immunotherapy of allergic rhinitis: new therapeutic opportunities with virus-like particles filled with CpG motifs

BACKGROUND

The incidence of allergic rhinitis (AR) has increased constantly over the last decades. The disease can significantly lower quality of life and subsequently might progress to allergic asthma. Allergen-specific immunotherapy is mostly used to cope with the cause of the disease. However, incidence of systemic reactions or limited compliance hampers the widespread use of this therapeutic approach. Therefore, new candidates are examined to improve immunotherapy of allergies. Recently, a new technology was developed with the aim to positively influence the immune system of allergic patients. Virus-like particles (VLPs) represent a potent vaccine platform that has been proven to be immunogenic and clinically effective. To enhance immune cell activation, addition of Toll-like receptor ligands and/or depot-forming adjuvants seems to be helpful. In this context, CpG motifs represent intensive investigated and potent stimulators of T cells. This article focuses on the function of VLPs and CpG motifs and their clinical experience for treatment of AR.

METHODS

A literature review was performed.

RESULTS

Several published studies showed a beneficial impact of the treatment on allergic symptoms. They tested VLPs filled with or without CpG motifs in combination with or without allergen.

CONCLUSION

Results encourage further investigations of VLPs and CpG motifs as adjuncts to or even alternative candidates for immunotherapy of allergic disorders.

New routes for allergen immunotherapy

IgE-mediated allergy is a highly prevalent disease in the industrialized world. Allergen-specific immunotherapy (SIT) should be the preferred treatment, as it has long lasting protective effects and can stop the progression of the disease. However, few allergic patients choose to undergo SIT, due to the long treatment time and potential allergic adverse events. Since the beneficial effects of SIT are mediated by antigen presenting cells inducing Th1, Treg and antibody responses, whereas the adverse events are caused by mast cells and basophils, the therapeutic window of SIT may be widened by targeting tissues rich in antigen presenting cells. Lymph nodes and the epidermis contain high density of dendritic cells and low numbers of mast cells and basophils. The epidermis has the added benefit of not being vascularised thereby reducing the chances of anaphylactic shock due to leakage of allergen. Hence, both these tissues represent highly promising routes for SIT and are the focus of discussion in this review.

Assessment of clinical efficacy of CYT003-QbG10 in patients with allergic rhinoconjunctivitis: a phase IIb study

BACKGROUND

Allergic symptoms are generally caused by exposure to substances to which people have become sensitized. Associated with this is an 'unbalanced' Th1/Th2 immune response with T cell responses skewed towards the production of Th2 cytokines, IL-4, 5, and 13 and high levels of IgE antibodies. Current immune modulating therapies require the use of allergens, carrying the risk to induce potentially severe allergic reactions.

OBJECTIVE

Goal of the present study was to assess the safety and efficacy of an allergen-free immune modulator in patients suffering from perennial allergy.

METHODS

In order to be protected from immediate degradation upon injection, a toll-like receptor 9 (TLR9) agonist was packaged into virus-like particles. These nanoparticles loaded with TLR9 ligands (CYT003-QbG10) were injected six times, at weekly intervals, into patients with house dust mite allergy in an attempt to ameliorate allergic symptoms by modifying the immune response towards allergens. Two different doses were compared against placebo in this double-blind, randomized phase IIb study (n=299). Public trial registry: http://clinicaltrials.gov (NCT00800332).

RESULTS

The treatment was safe and generally well tolerated. Rhinoconjunctivitis symptoms were significantly lower in patients treated with high dose of CYT003-QbG10 as compared with placebo (scores 0.31 vs. 0.52, P=0.04) based on a standardized average combined symptom and medication score. Furthermore, patients in the high dose group reported a significantly better quality of life score post-treatment than patients on placebo (scores 0.71 vs. 1.21, P=0.02). The conjunctival provocation test revealed a median 10-fold increase in allergen tolerance in the high dose group while in the placebo group it remained unchanged.

CONCLUSION AND CLINICAL RELEVANCE

Treatment with high-dose CYT003-QbG10 improved disease symptoms and reduced medication use in allergic individuals thus providing first evidence for a new potential immunotherapeutic.

Allergy vaccines: dreams and reality

Allergy, extrinsic asthma and atopic eczema derive from deregulated immune responses against innocuous antigens. The incidence of atopic diseases is actually affecting approximately 30% of the population in industrialized countries. Although much progress has been achieved in the development of efficient symptomatic treatments for allergic diseases, the only curative treatment remains allergen-specific immunotherapy. In contrast to classical vaccines, which elicit strong host immune responses after one or a few injections, allergen-specific immunotherapy might require a long treatment time of 3-5 years with up to 80 injections to confer some protection. The reality is that 'allergy vaccines' achieve beneficial effects through immunomodulation, which takes a long time to establish. The dream would be to develop highly efficient allergy vaccines able to cure the disease with a few injections.