Will drug-free therapy offer asthma relief?

Emma Baines reports on the development of a promising therapy for asthma patients

What is the story?
The first non-drug therapy for asthma has been hailed as ‘the biggest advance in treatment of the condition for a decade’ by the media.

The therapy, which involves inserting a probe into the lungs and ‘burning’ the muscle tissue, halves the risk of an asthma attack, the papers said.

They claimed the treatment works by altering the structure of the airways in the lungs and that the treatment could allow asthma patients to rely less on inhalers providing new hope for the millions asthmatics.

What is the research?
The media reports are based on a small safety and efficacy trial of a surgical procedure, known as bronchial thermoplasty.

Patients with severe asthma have previously been shown to have excess smooth muscle mass in their airway. This leads to increased bronchoconstriction and other asthma symptoms.

Bronchial thermoplasty is designed to improve asthma symptoms by reducing the smooth muscle tissue in the airways.

It involves inserting a catheter into the airway during bronchoscopy. It delivers 10-second bursts of radiofrequency energy to the airway wall, burning away the cells. Although the cell damage caused by the procedure heals over a three- to six-week period, the muscle cells removed by the heat do not grow back.

Patients undergo three bronchoscopies at three-week intervals during which between three and 10mm of smooth muscle tissue from the airway is removed.

The Asthma Intervention Re-search (AIR) trial was designed to test the safety and efficacy of this treatment for patients with moderate or severe asthma. It included 112 patients aged from 18 to 65 who had been treated with inhaled corticosteroids and long-acting beta2-adrenergic agonists (LABA). All had been shown to have poorly controlled asthma without inclusion of LABA treatment. The patients were assigned to bronchial thermoplasty or to continue with their usual treatment.

The researchers found that at three and 12 months after treatment, patients given bronchial thermoplasty suffered half as many mild asthma exacerbations as those on drug treatment alone.

After 12 months, their morning peak expiratory flow had improved by nearly 40 litres per minute. They also required rescue medication less often and had more symptom free days.

However, there was no statistically significant difference in the number of severe exacerbations experienced by patients in the bronchial thermoplasty or control groups.

In addition, patients who underwent bronchial thermoplasty were nearly four times as likely as those on usual therapy to have adverse respiratory events, such as dyspnoea, wheezing, productive cough and bronchospasm, during the six weeks following treatment.

There were six hospitalisations — four for exacerbation of asthma, one for the partial collapse of the left lower lobe and one for pleurisy.

What the researchers say?
Lead researcher Dr Gerard Cox, director of the division of respirology at McMaster University in Ontario, Canada, said: ‘These findings are very encouraging. They make us hopeful that bronchial thermoplasty may be a new option for asthma patients who have asthma symptoms despite use of current drug therapies.’

He said previous studies had shown that the clinical benefits of the treatment were stable up to two years following the procedure. Animal studies showed benefits lasting three years.

But the research is at an early stage and questions remain to be answered before the technique can be widely recommended to treat asthma, added Dr Cox: ‘We don’t yet know exactly which patients it is best suited to, or what happens to the cells, nerves, glands and other elements of the airway wall afterwards.’

He added that it was most likely to be used to treat moderate to severe asthma, and that patients would still have to take drug treatment afterwards.

‘Although we did find that patients needed less bronchodilator or rescue medication after bronchial thermoplasty, all patients in this trial still needed inhaled corticosteroids after treatment,’ he said.

What do other experts say?
Professor Martyn Partridge, professor of respiratory medicine at Imperial College in London, said that it was too soon to consider using bronchial thermoplasty as an alternative to drug treatment.

‘Each new study tells us more about the potential for bronchial thermoplasty but at this stage it is still helping us to understand the mechanisms involved in asthma and is not yet providing us with enough evidence that this intervention is a likely treatment for the average patient with asthma.’

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