New Research in Airway Diseases: An Interview With Gaetane C. Michaud, MD
In the fifth of this 6-part series, Gaetane C. Michaud, MD, chief of interventional pulmonary medicine at New York University (NYU) Langone Medical Center and associate professor of medicine, speaks with Pulmonology Advisor about upcoming research in airway stenting, particularly in COPD and asthma.
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I have been involved in a lot of airway interventions for benign airways disease, particularly small airways disease, including asthma and COPD. The most recent trial I have been involved in is what has been called the RENEW trial, which was published in JAMA in the spring of 2016.
The trial involved putting coils into the airways that are made of a piece of metal made of memory fibers that regains its coiled shape and shortens and stents open the airways, allowing trapped gas to escape. Initially we didn't quite understand what was happening, but based on the results of the RENEW trial, we know that it decreases that residual volume, so patients are able to get that volume out. When you think about what it feels like to have COPD, you can get the air in, but you can't get the air back out. You basically stack it up and then you worsen your mechanics. This allows the hemidiaphragms to go back into a better position. We give them back the mechanical advantage, so we have the muscles in a better position to function.
The study showed marked reduction in hyperinflation and marked loss of residual volume. This also translated into an improvement in quality of life and exercise tolerance. The study was a controlled trial in which we had patients randomly assigned either to controls or to intervention. With the study I participated in while I was at working at Yale, and despite it being a smaller site that didn't have a transplant program, we had a very large number of patients involved. A significant thing that came out of this trial is that we don't know who are going to be the responders yet. It is a study that are working on now with the company and with a couple of the other investigators. We are the lead site. What we are trying to do is figure out whether we can identify who is going to respond. At first we thought we were getting a lot of pneumonias and a lot of chest infections, and there were even points when we thought about having to close the trial because we were having so many pneumonias. It turns out that those pneumonias were really not infectious, and they were actually associated with the coils. I think that they were probably inflammatory responses to the coils, and what ends up happening is that you get these inflammatory responses and then you get fibrosis of the airway that doesn't allow hyperexpansion anymore, so patients feel remarkably better.
The study that I am working on now is looking to see whether or not there are correlates between the radiographic findings and the clinical syndrome that presents as the patient starting to feel unwell. They get flu-like symptoms and they start to have increased cough. So, we are trying to find heralds of good response. That way, we can turn around and look at those people and say, "What is different about those people compared to everybody else?" We can then perhaps look at a more focused population to see who is really going to benefit. Certainly the people who did benefit benefited significantly.
Sciurba FC, Criner GJ, Strange C, et al. Effect of endobronchial coils vs usual care on exercise tolerance in patients with severe emphysema: The RENEW randomized clinical trial. JAMA. 2016;315(20):2178-2189