Development of a novel bronchoscopic therapy for asthma

RationaleWe developed a potential treatment for asthma, targeting smooth muscle, so as to reduce the severity and frequency of bronchoconstriction.MethodsBronchial Thermoplasty with the AlairTM System is a novel bronchoscopic procedure that delivers controlled thermal energy to the airway wall, leading to inhibition of muscle function, and reduction in potential for bronchoconstriction. Treatment parameters, including total energy, target temperature, duration of treatment, numbers of target sites, were identified through animal studies. The structural consequences were assessed by histology and the functional effects by local methacholine (MCh) challenge. The Alair™ System was then deployed in subjects with a range of asthma severity. Outcomes included spirometry, MCh challenge, and daily diary recordings of peak flow, symptoms and medication usage. Treatments of accessible airways, diameter 3–10 mm, was done at 3–4 sessions, approximately three weeks apart.ResultsSixteen subjects with asthma were treated and followed for up to 2 years. Side effects were transient and typical of bronchoscopy; the most frequent were cough (71%) and wheeze (68%). No serious device-related adverse events occurred. At 12 weeks, there was no significant change in pulmonary function but there were improvements in symptom-free days (p=0.012) and peak flow measurements (p=0.01). All patients had improvement in PC20 over baseline; mean increase greater than two doublings (p<0.001). All 7 patients examined at 1 year still had PC20 values greater than baseline.ConclusionsThis experience suggests that Bronchial Thermoplasty can be safely carried out in selected subjects with asthma. The efficacy of this procedure is being examined through further clinical studies.