Stratified medicine in selecting biologics for the treatment of severe asthma

Biological treatments in childhood asthma

PURPOSE OF REVIEW

The aim is to update the information currently available for the use of biologics in severe asthma in children, in order to facilitate their prescription as far as possible.

RECENT FINDINGS

The appearance of biologics for the treatment of severe asthma has meant a revolutionary change in the therapeutic approach to this disease. Currently, five biologics have been approved for severe asthma in children and/or adolescents by the regulatory agencies: omalizumab, mepolizumab, benralizumab, dupilumab and tezepelumab. But despite their positive results in terms of efficacy, there are still relevant points of debate that should induce caution when selecting the most appropriate biologic in a child with severe asthma. Indeed, safety is essential and, for several of the existing treatments, the availability of medium-term to long-term data in this regard is scarce.

SUMMARY

The use of biologics can facilitate the therapeutic paradigm shift from pleiotropic treatments to personalized medicine. However, the choice of the most appropriate biologics remains a pending issue. On the other hand, to the extent that several of the biologics have been available for a relatively short time, the most robust evidence in terms of efficacy and safety in children is that of omalizumab.

[Hyper-IgE in internal medicine]

Hyper-IgE may be found under many pathological conditions. The role of IgE is essentially associated with the occurrence of allergic manifestations, which may be accompanied by an increase of their serum levels. Elevation of total IgE has also been reported in association with certain rare genetic immune deficiencies called hyper-IgE syndromes. Other circumstances such as infectious diseases, tumors or autoimmune diseases may also be accompanied by an excessive synthesis of IgE. Considering the diversity of these situations, discussion of the prognostic value of total IgE is useful to the internist.

Emerging biologics for the treatment of chronic rhinosinusitis

Chronic rhinosinusitis (CRS) is a prevalent chronic inflammatory disease of the nasal and paranasal cavities and is known to seriously impair quality of life in affected patients. CRS appears to be a heterogeneous group of diseases with different inflammatory and remodeling patterns, suggesting that not only different clinical phenotypes but also pathophysiological endotypes occur. CRS with nasal polyps (CRSwNP) is considered a more severe phenotype, especially when associated with comorbid asthma, as patients having this condition often do not respond to conventional treatment, including topical and systemic corticosteroids or surgery. Recently, studies with biologic agents have shown various effects in severe airway disease; specifically in Th2-biased CRSwNP, these effects were very promising. The greatest challenge for the future is to define the different endotypes of CRSwNP using easily accessible biomarkers to select the patients who have the best chance of a positive therapeutic response to innovative approaches.

[Personalised medicine for the diagnosis and treatment of allergic diseases]

Immunoglobulin E (IgE) mediated allergic diseases are characterised by heterogeneous clinical phenotypes and a large variety of different sensitisation patterns. Apart from genetic predisposition several environmental factors play a role in sensitisation and elicitation of symptoms. Since the majority of clinically relevant allergens are now available as purified recombinant allergens component-resolved in vitro diagnosis allows the sensitization profile of allergic patients to be determined at the molecular level. Such data may allow physicians to draw conclusions on the severity and persistence of a given allergic disease and to predict the outcome of allergen-specific immunotherapy (SIT) However, the potential of this approach needs to be demonstrated in controlled clinical trials. Moreover, in the context of atopic dermatitis, allergic rhinitis, allergic bronchial asthma as well as the atopic march several screening-biomarkers, diagnostic and prognostic biomarkers, biomarkers of severity and predictive biomarkers are presented and discussed in this article. Traditionally a relevant proportion of allergen-specific immunotherapies is performed in a personalised manner using named patient products manufactured on the basis of an individual prescription. Such named patient products are often mixtures containing several allergen extracts from different sources. However, there is no proven evidence for the safety and efficacy of this approach. In Germany the Therapy Allergen Ordinance ("Therapieallergene-Verordnung", TAV) regulates that in the future allergen products for SIT of insect venom allergies, allergies to pollen of early flowering trees and grass pollen and house dust mite allergies cannot be marketed as named patient products, but always require a marketing authorisation. Thus personalised SIT with named patient products is restricted to the treatment of less prevalent allergies, for which the generation of state-of-the-art clinical data is more difficult. Several recombinant allergens are currently evaluated in phase III clinical trials. In contrast to allergen extracts recombinant allergens offer the possibility to treat patients with a precisely adjusted mixture of the disease-eliciting allergen molecules. However, the implementation of this personalised approach to SIT within the given regulatory framework represents a challenge to regulators.

Pathophysiology of asthma: what has our current understanding taught us about new therapeutic approaches?

Current asthma therapy is based on the use of adrenergic bronchodilator and anti-inflammatory drugs the specificity, efficacy, duration of action, and safety of which have been derived through classical pharmacology and medicinal chemistry. That asthma is a T(H)2-type inflammatory disorder frequently associated with atopy and allergic comorbidities has led to a concentrated effort to find treatments that act selectively on this pathway. A systematic literature review was undertaken, as well as a review of the Web site Clinicaltrials.gov for ongoing trials. Targets have included T cells themselves and their associated cytokines, chemokines, and receptors mostly targeted with biological agents. With the exception of anti-human IgE, none of these have met the expectations predicted from animal models and human in vitro tests. For most of these new therapies, only a very small subpopulation appears to respond. A case is made for a different approach to drug discovery based on acquiring a greater understanding of asthma stratification, the relevant pathways involved, and the development of appropriate diagnostic tests enabling the targeting of selective treatments to those asthmatic phenotypes most likely to respond. The recognition that asthma is more than allergy mandates improved predictive animal models and an appreciation that many of the environmental insults that initiate, consolidate, and exacerbate asthma operate through an epithelium functioning in a disorderly fashion. An integrated model that places the epithelium at the forefront of asthma pathogenesis suggests that greater emphasis should be placed on therapeutics that increase the airways' resistance against the inhaled environment rather than focusing only on suppression of inflammation.