Effect of Biologic Therapies on Airway Hyperresponsiveness and Allergic Response: A Systematic Literature Review

Biologics and airway remodeling in asthma: early, late, and potential preventive effects

Although airway remodeling in severe and/or fatal asthma is stil considered irreversible, its individual components as a cause of clinical symptoms and/or lung function changes remain largely unknown. While inhaled glucocorticoids have not consistently been shown to affect airway remodeling, biologics targeting specific pathways of airway inflammation have been shown to improve lung function, mucus plugging, and airway structural changes that can exceed those seen with glucocorticoids. This superiority of biologic treatment, which cannot be solely explained by insufficient doses or limited durations of glucocorticoid therapies, needs to be further explored. For this field of research, we propose a novel classification of the potential effects of biologics on airway remodeling into three temporal effects: early effects (days to weeks, primarily modulating inflammatory processes), late effects (months to years, predominantly affecting structural changes), and potential preventive effects (outcomes of early treatment with biologics). For the identification of potential preventive effects of biologics, we call for studies exploring the impact of early biological treatment on airway remodeling in patients with moderate-to-severe asthma, which should be accompanied by a long-term evaluation of clinical parameters, biomarkers, treatment burden, and socioeconomic implications.

Efficacy of dupilumab for airway hypersecretion and airway wall thickening in patients with moderate-to-severe asthma: A prospective, observational study

BACKGROUND

Dupilumab has clinical effects in patients with moderate-to-severe asthma. When considering interleukin (IL)-4 and IL-13 signaling, effects of dupilumab on airway mucus hypersecretion and airway remodeling are expected, but they have been reported in only a few short-term studies. Its efficacy for airway hyperresponsiveness (AHR) remains unknown. We comprehensively assessed the efficacy of dupilumab, especially for subjective and objective measures of airway mucus hypersecretion and airway dimensions in moderate-to-severe asthmatic patients.

METHODS

In 28 adult patients with moderate-to-severe uncontrolled asthma, the comprehensive efficacy of 48-week dupilumab treatment, including the Cough and Sputum Assessment Questionnaire (CASA-Q), radiological mucus scores and airway dimensions on computed tomography (CT), was assessed prospectively. Treatment responsiveness to dupilumab was analyzed.

RESULTS

With 48-week dupilumab treatment, all four cough and sputum domain scores of CASA-Q improved significantly. Radiological mucus scores and airway wall thickening on CT were significantly decreased. The decreases in mucus scores were significantly associated with improvements in Asthma Control Questionnaire scores, Asthma Quality of Life Questionnaire (AQLQ) overall scores, airway obstruction, and airway type 2 inflammation. When defined by > 0.5 improvement in AQLQ overall scores, 18 patients (64%) were identified as responders.

CONCLUSIONS

Dupilumab reversed subjective and objective measures of airway mucus hypersecretion and some aspects of airway remodeling in patients with moderate-to-severe uncontrolled asthma.

Airway hyperresponsiveness in asthma: The role of the epithelium

Airway hyperresponsiveness (AHR) is a key clinical feature of asthma. The presence of AHR in people with asthma provides the substrate for bronchoconstriction in response to numerous diverse stimuli, contributing to airflow limitation and symptoms including breathlessness, wheeze, and chest tightness. Dysfunctional airway smooth muscle significantly contributes to AHR and is displayed as increased sensitivity to direct pharmacologic bronchoconstrictor stimuli, such as inhaled histamine and methacholine (direct AHR), or to endogenous mediators released by activated airway cells such as mast cells (indirect AHR). Research in in vivo human models has shown that the disrupted airway epithelium plays an important role in driving inflammation that mediates indirect AHR in asthma through the release of cytokines such as thymic stromal lymphopoietin and IL-33. These cytokines upregulate type 2 cytokines promoting airway eosinophilia and induce the release of bronchoconstrictor mediators from mast cells such as histamine, prostaglandin D2, and cysteinyl leukotrienes. While bronchoconstriction is largely due to airway smooth muscle contraction, airway structural changes known as remodeling, likely mediated in part by epithelial-derived mediators, also lead to airflow obstruction and may enhance AHR. In this review, we outline the current knowledge of the role of the airway epithelium in AHR in asthma and its implications on the wider disease. Increased understanding of airway epithelial biology may contribute to better treatment options, particularly in precision medicine.

RGS4 controls airway hyperresponsiveness through GAP-independent mechanisms

Regulators of G protein signaling (RGS) proteins constrain G protein-coupled receptor (GPCR)-mediated and other responses throughout the body primarily, but not exclusively, through their GTPase-activating protein activity. Asthma is a highly prevalent condition characterized by airway hyper-responsiveness (AHR) to environmental stimuli resulting in part from amplified GPCR-mediated airway smooth muscle contraction. Rgs2 or Rgs5 gene deletion in mice enhances AHR and airway smooth muscle contraction, whereas RGS4 KO mice unexpectedly have decreased AHR because of increased production of the bronchodilator prostaglandin E2 (PGE2) by lung epithelial cells. Here, we found that knockin mice harboring Rgs4 alleles encoding a point mutation (N128A) that sharply curtails RGS4 GTPase-activating protein activity had increased AHR, reduced airway PGE2 levels, and augmented GPCR-induced bronchoconstriction compared with either RGS4 KO mice or WT controls. RGS4 interacted with the p85α subunit of PI3K and inhibited PI3K-dependent PGE2 secretion elicited by transforming growth factor beta in airway epithelial cells. Together, these findings suggest that RGS4 affects asthma severity in part by regulating the airway inflammatory milieu in a G protein-independent manner.

Pathogenesis-based application of biologics for chronic rhinosinusitis: Current and future perspectives

Chronic rhinosinusitis (CRS) is heterogeneous and contains diverse pathogenesis including type 1, type 2, and/or type 3 inflammation. For severe type 2 CRS especially CRS with nasal polyps (CRSwNP), biologics that target inflammatory molecules have recently been applied along with further changes in the treatment algorithm for CRS. Currently, a completed phase 3 clinical trial for biologics for severe CRSwNP with inadequate response to surgery and/or intranasal corticosteroids, including omalizumab (anti-IgE), mepolizumab (anti-IL-5), benralizumab (anti-IL-5Rα), and dupilumab (anti-IL-4Rα), have all shown efficacy. Similar phase 3 clinical trials for tezepelumab (anti-TSLP) and etokimab (anti-IL-33) are now underway and completed, respectively. Further studies need to evaluate how to optimally and cost-effectively use biologics for CRS and determine if any biomarkers are indicative of which biologics should be administered. A definition of complete and/or clinical remission of CRS is also needed to determine when to reduce or discontinue biologics. In addition, more precise basic research on CRS, such as endotyping and genotyping, will need to be undertaken in order to determine novel targets for biologics.

Efficacy of Biologics in Patients with Allergic Severe Asthma, Overall and by Blood Eosinophil Count: A Literature Review

Patients with uncontrolled, allergic severe asthma may be prescribed biologic therapies to reduce exacerbations and improve disease control. Randomized controlled trials (RCTs) of these therapies have differed in design, with varying results overall and by baseline blood eosinophil count (BEC). This study describes published annualized asthma exacerbation rate (AAER) reductions from RCTs in patients with allergic severe asthma, overall and by baseline BEC category. A literature search was performed to identify published phase 3 RCT data of US Food and Drug Administration-approved biologics for severe asthma in patients with severe, uncontrolled asthma and confirmed sensitization to perennial aeroallergens. Analyses focused on AAER reduction versus placebo in the overall population and/or in those with an elevated or low BEC at baseline or screening. Baseline serum total immunoglobulin E levels varied between RCT populations. In patients with allergic severe asthma across all BEC categories, data were available for tezepelumab, dupilumab, benralizumab and omalizumab only; the greatest AAER reduction was observed with tezepelumab. In patients with allergic severe asthma and BECs of ≥ 260 cells/µL or ≥ 300 cells/μL, AAER reductions were observed with all biologics (tezepelumab, dupilumab, mepolizumab, benralizumab and omalizumab); the greatest AAER reduction was observed with tezepelumab and the smallest AAER reduction was observed with omalizumab. In patients with allergic severe asthma and BECs of < 260 cells/µL or < 300 cells/μL (regardless of historical BEC), an AAER reduction was observed with tezepelumab but not with benralizumab or omalizumab. Differential mechanisms of action may explain the differences in results observed between biologics. Among patients with allergic severe asthma, the efficacy of biologics in RCTs varied considerably overall and by BEC. Tezepelumab was the only biologic to demonstrate AAER reductions consistently across all subgroups. These differences can inform provider treatment decisions when selecting biologic treatments for patients with allergic severe asthma.

Personalized and Precision Medicine in Asthma and Eosinophilic Esophagitis: The Role of T2 Target Therapy

The role of type 2 inflammation has been progressively associated with many diseases, including severe asthma, atopic dermatitis, nasal polyposis, eosinophilic granulomatosis with polyangiitis, and, recently, eosinophilic esophagitis. Despite this, the association between asthma and esophagitis is still poorly known, and this is probably because of the low prevalence of each disease and the even lower association between them. Nonetheless, observations in clinical trials and, subsequently, in real life, have allowed researchers to observe how drugs acting on type 2 inflammation, initially developed and marketed for severe asthma, could be effective also in treating eosinophilic esophagitis. For this reason, clinical trials specifically designed for the use of drugs targeted to type 2 inflammation were also developed for eosinophilic esophagitis. The results of clinical trials are presently promising and envisage the use of biologicals that are also likely to be employed in the field of gastroenterology in the near future. This review focuses on the use of biologicals for type 2 inflammation in cases of combined severe asthma and eosinophilic esophagitis.