Bronchial thermoplasty: Redefining its role

[Markers of severity and predictors of response to treatment in severe asthma]

Asthma is a multifactorial disease with complex pathophysiology. Knowledge of its immunopathology and inflammatory mechanisms is progressing and has led to the development over recent years of increasingly targeted therapeutic strategies. The objective of this review is to pinpoint the different predictive markers of asthma severity and therapeutic response. Obesity, nasal polyposis, gastroesophageal reflux disease and intolerance to aspirin have all been considered as clinical markers associated with asthma severity, as have functional markers such as bronchial obstruction, low FEV1, small daily variations in FEV1, and high FeNO. While sinonasal polyposis and allergic comorbidities are associated with better response to omalizumab, nasal polyposis or long-term systemic steroid use are associated with better response to antibodies targeting the IL5 pathway. Elevated total IgE concentrations and eosinophil counts are classic biological markers regularly found in severe asthma. Blood eosinophils are predictive biomarkers of response to anti-IgE, anti-IL5, anti-IL5R and anti-IL4R biotherapies. Dupilumab is particularly effective in a subgroup of patients with marked type 2 inflammation (long-term systemic corticosteroid therapy, eosinophilia≥150/μl or FENO>20 ppb). Chest imaging may help to identify severe patients by seeking out bronchial wall thickening and bronchial dilation. Study of the patient's environment is crucial insofar as exposure to tobacco, dust mites and molds, as well as outdoor and indoor air pollutants (cleaning products), can trigger asthma exacerbation. Wider and more systematic use of markers of severity or response to treatment could foster increasingly targeted and tailored approaches to severe asthma.

Cost Utility of Bronchial Thermoplasty for Severe Asthma: Implications for Future Cost-Effectiveness Analyses Based on Phenotypic Heterogeneity

Background

Asthma is a disease with tremendous phenotypic heterogeneity, and the patients who are most severely impacted by the disease are high utilizers of the United States healthcare system. In the past decade, there has been many advances in asthma therapy for those with severe disease, including the use of a procedure called bronchial thermoplasty (BT) and the use of biologic therapy for certain phenotypes, but questions remain regarding the long-term durability and cost effectiveness of these therapies. The purpose of this analysis was (1) to assess the cost utility of BT relative to usual care (base case) and (2) to assess the cost utility of BT relative to usual care plus biologic therapy (omalizumab) (scenario analysis) based on updated 10-year clinical trial outcomes.

Methods

A Markov cohort model was developed and used to estimate the cost utility of BT to estimate the costs and quality-of-life impact of BT versus the comparisons over a 10-year time frame using a limited societal perspective, which included both direct health utilization costs and indirect costs associated with missed days of work, among those with severe persistent asthma.

Results

In the base case and the scenario analysis, BT was the dominant treatment strategy compared to usual care alone and usual care plus biologic therapy. The net monetary benefit for BT was $483,555.49 over a 10-year time horizon.

Conclusion

Cost-utility models are central to policy decisions dictating coverage, and can be extended to inform the patient and provider, during clinical decision-making, of the relative trade-offs of therapy, assessing long-term clinical and cost outcomes. Phenotypic classification of severe asthma is central to patient management and should also be integrated into economic analysis frameworks, particularly as new biologic agents are developed that are specific to a phenotype. Despite a larger upfront cost of BT therapy, there is a durable clinical and economic benefit over time for those with severe asthma.

Endoscopic Options for Moderate COPD, Chronic Bronchitis, and Uncontrolled Asthma

Until now, interventional therapies for patients with chronic obstructive pulmonary disease have been available in the form of lung volume reduction procedures as end-stage options. Currently, the range of indications is expanding to include earlier stages of the diseases. Lung denervation is available for moderate COPD, and patients with chronic bronchitis are being evaluated for endoscopic goblet cell ablation. Rheoplasty, metered spray cryo technique, and Karakoca resector balloon are used for this indication. But also, for patients with severe uncontrolled asthma, several techniques are available today. In addition to thermoplasty as a long-proven procedure, new and currently under investigation is the targeted lung denervation.Most of these techniques are currently being tested in large pivotal trials and it will soon become clear in which phenotype which technique will be used in the different forms and stages of obstructive diseases. The current paper presents the techniques and the currently available literature.

[Bronchial thermoplasty for severe asthma]

Bronchial thermoplasty has been developed over the past fifteen years and is the first endoscopic technique approved in the management of severe asthma. This procedure uses radiofrequency applied to the airway wall to target bronchial smooth muscle. Patients treated in randomized controlled trials have experienced significant decreases in the use of rescue medications, urgent care visits, and exacerbations rate. The lack of reliable predictive markers of response to this expensive, minimally-invasive technique currently makes it a last-line treatment option. We review the principles and supposed mechanisms of action of this treatment, the results from the main trials and clinical registry data and discuss the place of bronchial thermoplasty in the current management of severe asthma. We also discuss perspectives to better characterize the mechanisms of action and identify the responder phenotype, the main challenge of current studies.