Medical Device Daily Associate

A new surgical/device application being developed by early-stage firm Asthmatx (Mountain View, California) may lessen the need for vigilant medical therapy compliance and help to greatly alleviate the symptoms of asthma sufferers, especially those who are refractory to medication or who are simply non-compliant in taking their medication.

The company has developed a catheter-based procedure for the treatment for asthma that employs bronchial thermoplasty (BT), via its Alair system, to deliver thermal energy to the airway walls to reduce the presence of airway smooth muscle, the tissue responsible for airway constriction and breathing difficulties in asthma patients.

A study published in the May 1 issue of the American Journal of Respiratory and Critical Care Medicine (AJRCCM) reported the results of the company's initial clinical study of this investigational outpatient procedure for the treatment of asthma. In addition, the lead editorial in this edition of the AJRCCM, titled "Hot Stuff" Bronchial Thermoplasty for Asthma," supports the potential of this procedure as a completely new approach for treating severe asthma. Interestingly, it is the lone device-based treatment in the asthma space.

The primary objective of this feasibility study was to evaluate the safety of performing BT in patients with mild to moderate persistent asthma by examining its impact on lung function and airway responsiveness over two years.

"The data from this study, suggesting that bronchial thermoplasty may elevate the current standard of medical care for certain patients with asthma, are very exciting," Glen French, CEO of Asthmatx, told Medical Device Daily. "We have also completed two larger randomized and controlled studies, both of which are expected to be reported later this year, and we are well underway with our fourth clinical study, an FDA-approved IDE pivotal study, called the AIR2 Trial, at more than 30 top-tier medical centers around the world," he said.

The safety data reported in the study published in AJRCCM indicate that BT is well tolerated, and the long-term safety assessment at two years showed no deterioration in respiratory health status.

Patients reported satisfaction with the procedure, all indicating they would "definitely" or "probably" undergo the procedure again.

While the study evaluated the feasibility and safety of BT, results also revealed significant improvements in peak expiratory flow and symptom-free days, according to the company.

The data "further demonstrated significant improvement in airway responsiveness, out to two years," said Gerard Cox, MB, professor of medicine at McMaster University (Hamilton, Ontario) and principal investigator of the study. "These findings are encouraging and provide important direction for the design of further studies to examine how bronchial thermoplasty may help asthma patients who do not respond well to current drug therapies."

French described BT as an out-patient procedure performed through a standard flexible bronchoscope introduced through the patient's nose or mouth and into the lungs.

The small-diameter Alair catheter is delivered into the airways through the working channel of this flexible bronchoscope. The tip of the Alair catheter is then expanded to contact the walls of targeted airways.

Controlled thermal energy is then delivered to the airway walls to reduce the presence of muscles within the airway wall that narrow the airways in patients with asthma. During the procedure radio frequency energy is delivered to the airway wall. The tissue heats up to about 149 degrees, high enough to reduce smooth muscle mass but low enough to avoid tissue destruction and scarring.

"[BT] targets airway smooth muscle with an absolute minimum of collateral damage," said French.

Although the procedure is still under clinical investigation, the data from this study supports the company's contention that reducing the amount of airway smooth muscle may reduce the ability of treated airways to constrict or narrow. The procedure, like many other flexible endoscopy procedures, is done under light anesthesia, and the patient returns home the same day. Usually three separate treatment episodes are required to treat all the accessible airways of both lungs.

The company poses the theory that the smooth muscle layer is an evolutional vestige, much like the appendix. Perhaps as an analogy, our distant mammalian relative, the whale, still has quite a lot of smooth muscle and likely uses it to keep its breathing apparatus pressurized during long dives.

In humans, smooth muscle is, unfortunately, a rather useless appendage, which often becomes inflamed and restricts the airways. Thus, French noted that this smooth muscle has been referred to as "the appendix of the lung."

In the U.S., French said the 300-patient AIR2 trial will investigate a much more severe asthma patient population than previous studies abroad and in Canada.

Under the auspices of an investigational device exemption, the U.S. pivotal trial will evaluate the use of BT "in patients who are taking the highest doses of state-of-the-art medication and yet are still symptomatic," French said.

These patients generally take a cocktail of inhaled corticosteroids and long-acting broncho dilators, both found in the popular asthma drug Advair.

This initial U.S. refractory patient population represents about 10% of asthma sufferers.

According to the American Lung Association (New York), more than 20 million Americans have asthma, and about two-thirds of these (13.3 million) patients are adults. Out of this eligible adult patient population, French said there are roughly 1.3 million patients who would fall into the U.S. pivotal study parameters.

"We have data that suggests that we may benefit patients across the spectrum of disease severity, essentially half of the market if you will," French said. He also noted that while the company cannot make the claim that the procedure is permanent, "it has data that to suggest that the procedure lasts for at least three years." And he cited the instance of one patient who has had positive results out to five years.

Asthmatx was founded by MedVenture Associates venture partner Michael Laufer, MD, an inventor who also founded Broncus Technologies (also Mountain View), which is developing the Exhale system, used in airway bypass procedures to reduce the hyper-inflation in patients with emphysema.

Asthmatx was spun off from Broncus in 2003 and most recently raised $27.2 million in a Series C round in December (Medical Device Daily, Dec. 21, 2005).