Tezepelumab and Mucus Plugs in Patients with Moderate-to-Severe Asthma

Tezepelumab in patients with allergic and eosinophilic asthma

Asthma is a heterogeneous disease commonly driven by allergic and/or eosinophilic inflammation, both of which may be present in severe disease. Most approved biologics for severe asthma are indicated for specific phenotypes and target individual downstream type 2 components of the inflammatory cascade. Tezepelumab, a human monoclonal antibody (immunoglobulin G2λ), binds specifically to thymic stromal lymphopoietin (TSLP), an epithelial cytokine that initiates and sustains allergic and eosinophilic inflammation in asthma. By blocking TSLP, tezepelumab has demonstrated efficacy across known asthma phenotypes and acts upstream of all current clinically used biomarkers. In a pooled analysis of the phase 2b PATHWAY (NCT02054130) and phase 3 NAVIGATOR (NCT03347279) studies, compared with placebo, tezepelumab reduced the annualized asthma exacerbation rate over 52 weeks by 62% (95% confidence interval [CI]: 53, 70) in patients with perennial aeroallergen sensitization (allergic asthma); by 71% (95% CI: 62, 78) in patients with a baseline blood eosinophil count ≥300 cells/μL; and by 71% (95% CI: 59, 79) in patients with allergic asthma and a baseline blood eosinophil count ≥300 cells/μL. This review examines the efficacy and mode of action of tezepelumab in patients with allergic asthma, eosinophilic asthma and coexisting allergic and eosinophilic phenotypes.

Airway remodelling in asthma and the epithelium: on the edge of a new era

Asthma is a chronic, heterogeneous disease of the airways, often characterised by structural changes known collectively as airway remodelling. In response to environmental insults, including pathogens, allergens and pollutants, the epithelium can initiate remodelling via an inflammatory cascade involving a variety of mediators that have downstream effects on both structural and immune cells. These mediators include the epithelial cytokines thymic stromal lymphopoietin, interleukin (IL)-33 and IL-25, which facilitate airway remodelling through cross-talk between epithelial cells and fibroblasts, and between mast cells and airway smooth muscle cells, as well as through signalling with immune cells such as macrophages. The epithelium can also initiate airway remodelling independently of inflammation in response to the mechanical stress present during bronchoconstriction. Furthermore, genetic and epigenetic alterations to epithelial components are believed to influence remodelling. Here, we review recent advances in our understanding of the roles of the epithelium and epithelial cytokines in driving airway remodelling, facilitated by developments in genetic sequencing and imaging techniques. We also explore how new and existing therapeutics that target the epithelium and epithelial cytokines could modify airway remodelling.

Tezepelumab for Severe Asthma: One Drug Targeting Multiple Disease Pathways and Patient Types

Asthma is a heterogeneous inflammatory disease of the airways, affecting many children, adolescents, and adults worldwide. Up to 10% of people with asthma have severe disease, associated with a higher risk of hospitalizations, greater healthcare costs, and poorer outcomes. Patients with severe asthma generally require high-dose inhaled corticosteroids and additional controller medications to achieve disease control; however, many patients remain uncontrolled despite this intensive treatment. The treatment of severe uncontrolled asthma has improved with greater understanding of asthma pathways and phenotypes as well as the advent of targeted biologic therapies. Tezepelumab, a monoclonal antibody, blocks thymic stromal lymphopoietin, an epithelial cytokine that has multifaceted effects on the initiation and persistence of asthma inflammation and pathophysiology. Unlike other biologic treatments, tezepelumab has demonstrated efficacy across severe asthma phenotypes, with the magnitude of effects varying by phenotype. Here we describe the anti-inflammatory effects and efficacy of tezepelumab across the most relevant phenotypes of severe asthma. Across clinical studies, tezepelumab reduced annualized asthma exacerbation rates versus placebo by 63-71% in eosinophilic severe asthma, by 58-68% in allergic severe asthma, by 67-71% in allergic and eosinophilic severe asthma, by 34-49% in type 2-low asthma, and by 31-41% in oral corticosteroid-dependent asthma. Furthermore, in all these asthma phenotypes, tezepelumab demonstrated higher efficacy in reducing exacerbations requiring hospitalizations or emergency department visits versus placebo. In patients with severe uncontrolled asthma, who commonly have multiple drivers of inflammation and disease, tezepelumab may modulate airway inflammation more extensively, as other available biologics block only specific downstream components of the inflammatory cascade.

Associations of fractional exhaled nitric oxide with airway dimension and mucus plugs on ultra-high-resolution computed tomography in former smokers and nonsmokers with asthma

BACKGROUND

Associations of fractional exhaled nitric oxide (FeNO) with airway wall remodeling and mucus plugs remain to be explored in smokers and nonsmokers with asthma. Ultra-high-resolution computed tomography (U-HRCT), which allows accurate structural quantification of airways >1 mm in diameter, was used in this study to examine whether higher FeNO was associated with thicker walls of the 3rd to 6th generation airways and mucus plugging in patients with asthma.

METHODS

The retrospective analyses included consecutive former smokers and nonsmokers with asthma who underwent U-HRCT in a hospital. The ratio of wall area to summed lumen and wall area was calculated as the wall area percent (WA%). Mucus plugging was visually scored.

RESULTS

Ninety-seven patients with asthma (including 59 former smokers) were classified into low (<20 ppb), middle (20-35 ppb), and high (>35 ppb) FeNO groups (n = 24, 26, and 47). In analysis including all patients and subanalysis including nonsmokers or former smokers, WA% in the 6th generation airways was consistently higher in the high FeNO group than in the low FeNO group, whereas WA% in the 3rd to 5th generation airways was not. In multivariable models, WA% in the 6th generation airways and the rate of mucus plugging were higher in the high FeNO group than in the low FeNO group after adjusting for age, sex, body mass index, smoking status, lung volume, and allergic rhinitis presence.

CONCLUSIONS

Higher FeNO may reflect the inflammation and remodeling of relatively peripheral airways in asthma in both former smokers and nonsmokers.

Do Biologic Therapies Decrease Mucus Plugging in Asthma?

Asthma researchers have long recognized that abnormal mucus production and clearance play a role in the pathophysiology of asthma.1 Mucus plugs are known to be common in patients with severe asthma, and mucus plug scores, for which higher scores indicate more severe plugging, are directly correlated with airflow obstruction and markers of eosinophilic airway inflammation (i.e., higher scores or marker levels are associated with more severe obstruction). Other work has shown that mucus plugs were associated with distal deficits in regional ventilation as delineated by hyperpolarized gas magnetic resonance imaging.2,3.