Bronchial Thermoplasty Comparable to Omalizumab for Severe Asthma

A once-in-lifetime intervention of bronchial thermoplasty (BT) was found comparably effective to once or twice-monthly injections of omalizumab (Xolair, Genentech and Novartis) for uncontrolled severe asthma, in a novel comparison of their respective clinical trials.

Robert Niven, MD (pictured), of the University of Manchester, in the UK, and colleagues undertook an Indirect Treatment Comparison (ITC) of the 2 interventions, as both have been suggested in allergist guidelines for uncontrolled severe asthma, but without direct comparisons available to help guide choice.

"No trial has directly compared BT and omalizumab and, while a randomized controlled trial comparing these 2 treatments would be ideal, there would be significant, perhaps intractable challenges in maintaining subject blinding when comparing an interventional procedure with an injected drug," the authors wrote.

"It is not hard to imagine a treatment that you do once and appears to last for 5 years might turn out to be more cost-effective than treatments that need to be given continuously,” Niven told MD Magazine. “Hence, the concept of an indirect cost-effective analysis; as a direct one is unrealistic as a project.”

Niven and colleagues based their ITC analysis on the Bucher method which, they explained, enables comparison of treatment effect magnitude in studies of different treatment modalities which use a common reference, such as placebo, and randomize patients to the active and control conditions.

The researchers identified 1 trial with BT that was double-blind and utilized a sham procedure as control, albeit noting that the sham control in this population would now likely be considered unethical. Two randomized, double-blind placebo-controlled trials with OM also met inclusion criteria for the ITC. The double-blind design offered the least bias and best quality data available for each treatment, Niven and colleagues indicated.

The BT procedure involves delivery of controlled thermal energy to the airway wall, reducing airway smooth muscle mass and reducing muscular capacity to constrict the airway in either allergic or non-allergic asthma. Omalizumab is 1 of the monoclonal antibody treatments which target serum-free immunoglobulin E (IgE) to interrupt the inflammatory cascade in allergic asthma. Each of the interventions has been evaluated in their respective clinical trials and found safe and effective.

This ITC assessed the respective rate ratios (RR) of severe asthma exacerbations, and exacerbation related events such as hospitalizations, emergency department visits, and unscheduled physician office visits; as well as a change in total score on the asthma-related quality-of-life questionnaire (AQLQ).

The researchers found BT had lower RR for asthma-related emergency department visits, while OM had statistically lower RR for asthma-related exacerbations. There was no statistical difference between the treatments in the exacerbation-related hospitalizations or unscheduled physician office visits. The treatments were also similar in the association with significant improvement in AQLQ total scores, and in the proportion of patients achieving the threshold of apparent clinical improvement.

"There is a large proportion of patients within severe asthma clinics who are not suitable for omalizumab or, indeed, mepolizumab (Nucala, GlaxoSmithKline), or who don't respond and there is an apathy internationally to attempt to use BT as an alternative in this group," Niven commented. "As a result, patients are being under-treated and are missing out on a valuable and cost-effective treatment option."

The Indirect Treatment Comparison of bronchial thermoplasty and omalizumab for uncontrolled severe asthma was published online July 14 in the Journal of Asthma.