Predicting response to bronchial thermoplasty in patients with severe uncontrolled asthma: An elusive goal

Bronchial thermoplasty in severe asthma: a real-world study on efficacy and gene profiling

Background

Bronchial thermoplasty (BT) is an effective treatment in severe asthma. How to select patients who more likely benefit from BT is an unmet clinical need. Moreover, mechanisms of BT efficacy are still largely unknown. We sought to determine BT efficacy and to identify potential mechanisms of response.

Methods

This retrospective cohort study evaluated clinical outcomes in 27 patients with severe asthma: 13 with T2-high and 14 with T2-low endotype. Expression levels of 20 genes were compared by real-time PCR in bronchial biopsies performed at the third BT session versus baseline. Clinical response was measured based on Asthma Control Questionnaire (ACQ) score < 1.5, asthma exacerbations < 2, oral corticosteroids reduction of at least 50% at 12 months post-BT. Patients were classified as responders when they had at least 2 of 3 outcome measures.

Results

81% of patients were defined as responders. BT induced a reduction in alpha smooth muscle actin (ACTA2) and an increase in CD68, fibroblast activation protein-alpha (FAP), alpha-1 and alpha-2 type I collagen (COL1A1, COL1A2) gene expression in the majority of patients. A higher reduction in ubiquitin carboxy-terminal-hydrolase L1 (PGP9.5) mRNA correlated with a better response based on Asthma Quality of Life Questionnaire (AQLQ). Lower changes in CD68 and FAP mRNAs correlated with a better response based on ACQ. Lower levels of occludin (OCLN), CD68, connective tissue growth factor (CTGF), higher levels of secretory leukocyte protease inhibitor (SLPI) and lower changes in CD68 and CTGF mRNAs were observed in patients who had less than 2 exacerbations post-BT. Lower levels of COL1A2 at baseline were observed in patients who had ACQ < 1.5 at 12 months post-BT.

Conclusions

BT is effective irrespective of the asthma endotypes and seems associated with airway remodelling. Quantification of OCLN, CD68, CTGF, SLPI, COL1A2 mRNAs could be useful to identify patients with better results.

Trial registration: The study protocol was approved by the Local Ethics Committee (Azienda USL-IRCCS of Reggio Emilia—Comitato Etico Area Vasta Nord of Emilia Romagna; protocol number: 2019/0014076) and all the patients provided written informed consent before participating in the study.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13223-022-00680-4.

The therapeutic effects of bronchial thermoplasty evaluated by cardiopulmonary exercise testing : a case series

Bronchial thermoplasty (BT) had been reported to improve the symptoms of severe asthma. However, the exertional responses of BT based on the mechanisms have not been elucidated. A 57-year-old man and a 60-year-old woman underwent BT due to intractable severe asthma. We evaluated the therapeutic effects of BT using cardiopulmonary exercise testing (CPET). After BT, the exercise time during CPET substantially prolonged reducing exertional dyspnea in the former (good), but not in the latter (poor). In the good responder, the high air remaining in the lung after expiration (i.e., inspiratory tidal volume minus expiratory tidal volume) during CPET decreased after BT. In contrast, in the poor responder, the high air remaining after expiration during exercise was not obtained before BT. Further investigations are necessary to confirm that the presence or absence of the exertional wasted ventilation on CPET may be informative to evaluate the therapeutic effects of BT. J. Med. Invest. 67 : 386-390, August, 2020.

Recent Developments In Bronchial Thermoplasty For Severe Asthma

PURPOSE

Bronchial thermoplasty is approved in many countries worldwide as a non-pharmacological treatment for severe asthma. This review summarizes recent publications on the selection of patients with severe asthma for bronchial thermoplasty, predictors of a beneficial response and developments in the procedure and discusses specific issues about bronchial thermoplasty including effectiveness in clinical practice, mechanism of action, cost-effectiveness, and place in management.

RESULTS

Bronchial thermoplasty is a treatment option for patients with severe asthma after assessment and management of causes of difficult-to-control asthma, such as nonadherence, poor inhaler technique, comorbidities, under treatment, and other behavioral factors. Patients treated with bronchial thermoplasty in clinical practice have worse baseline characteristics and comparable clinical outcomes to clinical trial data. Bronchial thermoplasty causes a reduction in airway smooth muscle mass although it is uncertain whether this effect explains its efficacy since other mechanisms of action may be relevant, such as alterations in airway epithelial, gland, and/or nerve function; improvements in small airway function; or a placebo effect. The cost-effectiveness of bronchial thermoplasty is greater in countries where the costs of hospitalization and emergency department are high. The place of bronchial thermoplasty in the management of severe asthma is not certain, although some experts propose that bronchial thermoplasty should be considered for patients with severe asthma associated with non-type 2 inflammation or who fail to respond favorably to biologic therapies targeting type 2 inflammation.

CONCLUSION

Bronchial thermoplasty is a modestly effective treatment for severe asthma after assessment and management of causes of difficult-to-control asthma. Asthma morbidity increases during and shortly after treatment. Follow-up studies provide reassurance on the long-term safety of the procedure. Uncertainties remain about predictors of response, mechanism(s) of action, and place in management of severe asthma.

Long-term responsiveness to mepolizumab after failure of omalizumab and bronchial thermoplasty: Two triple-switch case reports

Severe asthma affects between 5 and 10% of patients with asthma worldwide and requires best standard therapies at maximal doses. A subgroup of patients remains refractory to all treatments. We describe two case reports with severe allergic asthma who progressively worsened over the years despite the best therapy. The patients were first treated with omalizumab, which was completely ineffective, and then with bronchial thermoplasty (BT), again without clinical benefit. Since our patients met the AIFA criteria for inclusion in mepolizumab treatment, a therapy with this anti-IL5 biological agent was initiated. In the first case (a 53-year-old female), after the second mepolizumab administration, symptoms improved progressively, with a reduction in the number and severity of exacerbations, so the patient could finally be discharged from hospital. At follow-up, it was possible to reduce oral corticosteroids and continuing with inhaled corticosteroids/long-acting beta-agonists and montelukast. The patient had only one exacerbation/year. Symptom control and quality of life improved significantly. In the second case report (a 55-year-old male), after the sixth mepolizumab administration, symptoms improved progressively, with a reduction in the number and severity of exacerbations. At follow-up, it was possible to reduce and stop oral corticosteroids, continuing with inhaled therapy and montelukast. Symptom control and quality of life improved significantly.These are the first cases of patients unresponsive to sequential omalizumab and BT but with good and prolonged clinical response to mepolizumab. Both cases suggest that also after the failure of two consecutive third-line treatments, a third treatment (mepolizumab) should be attempted.