Innovations in Pulmonary Stents for Cancer Patients

Podcast Transcript

Dale Shepard, MD, PhD: Cancer Advances at Cleveland Clinic podcast for medical professionals, exploring the latest innovative research in clinical advances in the field of oncology. Thank you for joining us for another episode of Cancer Advances. I'm your host, Dr. Dale Shepard, a medical oncologist here at Cleveland Clinic overseeing our Taussig Phase I and Sarcoma Programs. Today I'm happy to be joined by Dr. Tom Gildea, an interventional pulmonologist and Section Head of Bronchology in the Respiratory Institute here at Cleveland Clinic. He's here today to talk to us about pulmonary stents for patients with lung cancer. So welcome, Tom. Thanks for joining us today. Maybe you can start by telling us a little bit about what you do here at Cleveland Clinic.

Thomas Gildea, MD: Thanks Dale. Thanks for having me. Well, I'm an interventional pulmonologist. An interventional pulmonologist is a relatively new subspecialty of pulmonary or critical care medicine. It requires some extra training. That specialty actually is only been around a number of years. We wrote a board certification, I think back in 2014, and now it's an extra year of training beyond pulmonary care. I've been doing that for a number of years and it's specialized training around procedures and special expertise around doing things related to sort of rigid and flexible bronchoscopy and medical plural procedures, really around therapeutic interventions in plural and airway space for patients with lung disease. So I'm the sort of program director and head of that section. And I'm oversee the clinical operations of a large group of individuals who work in that section. And we take care of lots of patients who have basic and advanced bronchoscopy everything from diagnostic procedures up through major therapeutic interventions.

Dale Shepard, MD, PhD: Excellent. So today we're going to talk about pulmonary stents and maybe we have a wide range of people who listen to this podcast. So if we can start basic, what is a stent? Tell us about what a stent is.

Thomas Gildea, MD: Sure. So a stent is really a device or a prosthesis that people are probably more familiar with from the cardiac space. So a lot of people are familiar with a cardiac stent. It's a tube like structure that's put in there in a person to try to hold a vessel open. In the case of a cardiac stent. We have a similar device that we put into the airway. It could be put in the trachea or a bronchus, literally designed to hold open the airway so people can breathe better or to cough out mucus or secretions. It's the same general concept. And we have lots of different kinds of stents. So the cardiac folks, the vascular people put in stents, we also have stents made of metal or plastic, silicone stents, and same general concept of what they're used for.

Dale Shepard, MD, PhD: Excellent. So when we think about pulmonary stents, what are the most common things that you use stents for? You mentioned things about secretions and is this mostly for patients who come in with a new diagnosis or complications of their treatments, or what is the usual setting that you see patients?

Thomas Gildea, MD: So, unfortunately, most of the time, these are placed in patients with a symptomatic airflow obstruction. So we call this central airway obstruction and the most common circumstances, individuals with cancers. And typically that would mean an advanced stage cancer. So as we all know, patients with cancer that is spread to the middle of the chest or the mediastinum that causes compression or obstruction of an airway is typically an advanced stage cancer. When that happens, people feel very short of breath, and there are times when we can intervene to either open up the airway by some mechanism of sort of burning out the tumor or lasering out the tumor, or just cutting out the tumor, or when we can't do that, we can put in these stents to hold open the airway so they can breathe better. So we can be of initial treatment, or it could be part of palliative treatment. If, for example, a surgery or more definitive therapy is not amenable or they're not available to the patient. Dale Shepard, MD, PhD: So I know that you've been working with stents for a number of years. How, how did you get involved with sort of developing stents and tell me a little bit about that journey that you've taken to sort of really come up with more custom stents.

Thomas Gildea, MD: So generally speaking, putting a stent in someone is general bad. We do everything humanly possible to not put stents in. So when you can imagine that you have these amazing resources, amazing reflexes that your body has to cough things in out. So generally speaking, you're not supposed to have things in your lungs. We try to cough everything out. And so when we have to go and put something in your airway to hold it open your body doesn't like that. And so stents are universally not well tolerated by people. You really have to put them in only if they're absolutely necessary. So stents are prone to having problems with granulation tissue. So when the stent is sitting there and it can rub against the walls, we can have problems with tissue being formed up at the ends because the air goes in and out, and the mucus has to be coughed out.

The stent can sometimes cover up that surface, the airway that's designed to move mucus out. Mucus can get stuck in the stent. And so we have to be on medicines to keep that clear and that can be a problem over time. And then you can get infected. The stents can have that mucus get stuck on there. It can get infected. So, that can be a problem. And of course, if people get treatments or the stent doesn't sit right, it can get coughed loose and move. And so the vast majority of patients, if the stent is left in long enough will cause problems. It can have any of those problems, either one individually or multiple. And so a stent is always an option of last resort. And so we spend a lot of time and effort managing patients with stents for all the complications. And so because of that, I've spent a great number of years learning how to use stents in the best of circumstances, how to use stents only when absolutely necessary, trying to find other techniques to use instead of stents. And then when I do have to use the stent, we have different kinds of stents to use in special circumstances. And then we've gotten even to the point of learning how to modify the stents. To use them to avoid some of the complications. So in the case of say, silicone stents, silicone stents had been out since the early 1990s, that's a plastic device that we can put in that requires a rigid bronchoscope and a really an operative procedure. When we put those stents in, because they're plastic, I can cut them, I can shape them, I can cut holes in them. And because I can do that, I can really make it almost any configuration of size that I want, but because they only come in tube sizes, I can sometimes take them in so additional branches on and really craft them into what I want them to be.

And so for a number of years, we would take stents like that and make exactly what we want to fit into patients. Similar to work that's been done here by other folks in the vascular space years ago, and we've sort of modify those ideas for the airway. And so as patients have been fortunate enough to live longer with folks like you in the oncology world, doing amazing things with radiation and chemotherapy, or in cases of patients with non-cancerous disease that can live longer. The stents, if you live long enough will become the problem. So we worked on processes of using 3D printing to make appropriate size stents and making stents that would fit exactly to the airway. And so that's the projects that we've been working on for a number of years.

Dale Shepard, MD, PhD: And so with the 3D modeling, for instance, what sort of timeframe is involved. So certainly some of the other implants and things that utilize 3D printing, it's kind of long process. These sound like patients who are pretty sick and may not have a lot of time for design. So, what kind of timeframe does that entail?

Thomas Gildea, MD: Yeah, so for the most part, patients with cancer, we generally use off the shelf stents and we stabilize the airways. But again, if they are fortunate enough to live a long time and they need something custom made, we can make a custom, or make a 3D printed, or 3D printing associated, or augmented stent. It takes about a week to make one of those, but that requires a few steps. So we get the patient's cat scan. We use the cat scan as the base model. We take that cat scan and we do, what's called segmentation. We take the airway component of the cat scan out, and we make a three dimensional model of the airway from that three dimensional model. I can overlay a prescription of what I think that airway stent should look like. And then we take that three dimensional prescription off into the manufacturing world.

They convert that into a mold. That mold is then printed. And then we do the pressure inject to the Silicon. That whole process takes about a week. And that's just today. We hope to be able to shorten that time down quite a bit and it's just a full disclosure. I'm the inventor of this. And the Cleveland Clinic has a spinoff company and all that's sort of in the works. And so we do have those things in place around that kind of stuff. So right now it takes about a week to get those products off the ground. And so, if it's not really used in emergency, but it's used as a long term management plan for individuals who really need stents for long term and who are going to survive long enough to need them.

Dale Shepard, MD, PhD: And you mentioned this was used a rigid bronchoscope and is kind of an operative procedure to put these stents in from a patient perspective. What does the process look like? What sort of recovery time? How long is a procedure? What does that look like?

Thomas Gildea, MD: Yeah, for the most part, these are outpatient procedures. We do them under general anesthesia, but you can still come in and go home on the same day, as long as they're not in the hospital to begin with for some other respiratory problem. So it's a general anesthesia procedure. There's no incision. So we just go through the mouth under general anesthesia with a scope down through the open mouth, into the airway. Rigid scope is essentially a hollow tube, several millimeters of an empty tube. And we ventilate the patient through that tube. I will then go into the airway and then load up the silicone stent and squish it down into a small tube and then deploy it in the airway, and then fix it in position using some instruments to sort of rotate it and twist it and get it in spot.

And then once it's in position, that's it. Once it's in, I just back out and take some nice pictures and then there it is. And then within a few minutes, you can wake up. We take all the tubes out. You're breathing on your own and you should feel much better. Most people feel much better from a breathing standpoint, almost immediately. It's not painful in any way. Again, there're no incisions. And we put, let people wake up in the recovery and we give them some inhalers and medications to go home on to help keep their secretions clean. And then they go home. And the idea is that we generally see them back in about four to six weeks to go in and check in on a stent, clean it up, look inside and I'd make sure there are no problems. And, and then we just manage it. The expectation is those stents stand for about a year. Although, we do have to go in occasionally to clean up any of the expected complications I described, any mucus clearance or granulation tissue. And there's also an opportunity from time to change the prescription. If the airways change over time, or if I need to make some adjustments, I can do that on the fly. So really it's an outpatient procedure. It's not really painful in any way. Just some scratches to the throat. People basically go home the same day.

Dale Shepard, MD, PhD: When we think about the airways that you're working with, trying to open up those airways. How far down into the lungs? How small are the airways that you end up putting stents? I guess at some point, probably if you get peripheral enough, you don't really get a lot of benefits. So, how large of an airway do you put stent into?

Thomas Gildea, MD: Yeah, that's a Great question. So right now, most of the world's literature is basically limited to large central airways. So the trachea and the main bronchus, both bright and main bronchus are most commonly done. We can also do the airway between the right upper and the right lower that's called the bronchus intermedius. But right now we do have the ability to get into the low bar airways, both the upper and lower lungs.

Dr. Sethi here, my partner has done some work looking at salvaging lobes, getting down to that level of detail. The custom stents, we can go down to six millimeter airways when necessary with really just lobes and the 3d printing and all that sort of stuff. They're all why stents are all branch stents. So we're really looking at lobes as the smallest possible airway that we can salvage, but most things are done at the level of individual, right or left lung. That's pretty much the major extent of these things. Anything that extends beyond those larger airways, either a lobe or a main bronchus. The chances of recovering the airway are very, very small. The chances of deriving any benefit are very, very small and the risks go very, very high. So if we start to dig into very, very small airways, we can run into problems with blood vessels and harming the patient. At that point, they don't have much value beyond that size.

Dale Shepard, MD, PhD: Makes sense. You previously mentioned that you really tried to do stents only when you need to. And there were some other techniques that were being developed to help out? What are some of those other techniques that someone might consider instead of a stent? When you're having a discussion with a patient about doing a stent, what other alternatives do you typically offer?

Thomas Gildea, MD: So if there is a possibility that we can just sort of clear the tumor out from the airway, just sort of snipping it out, or burning it out. That's usually the first option. Clearly, if they're a surgical candidate, if they can be operated upon and have that cancer removed from their body, that would be the best option. So if they are a surgical candidate and they can be cured, or at least have a long term surgical outcome, we would prefer that. If they're not curable and we can't sort of get it out of the airway and they're not feeling terribly bad, radiation and chemotherapy as primary therapies to try to keep from instrumenting the airway. Sometimes we can do balloon dilation. Sometimes there are therapies like photodynamics therapy or cryotherapy, or a number of other endoluminal therapies to try to treat tumor from coming back quickly are available to us.

There are things on the experimental horizons around microwave therapy and other endoluminal chemotherapy options and stuff that are on the horizon. But really it comes down to cancer treatment. If you can get the cancer treatment, right, we hopefully will never have to use under bronchial prosthetic devices.

Dale Shepard, MD, PhD: Makes sense. So when we think about people who might be listening, thinking about, "well, hey I have a patient that might benefit from a stent at some point." What are the kinds of things that you see that we can do here at the Cleveland Clinic that might not be available locally? So, I guess the question is how widespread is the ability for patients to get stents? And are what would be an ideal patient you would like to see? Because you might be able to offer them something maybe in an addition to what they could get locally.

Thomas Gildea, MD: Sure. So anytime that there is tumor wrapped around the central airway, around the central trachea, or somewhere near the mainstem bronchi, where there's seems to be impingement, these are patients that we'd like to know about sooner rather than later, so that there may be an opportunity to treat them. Any time we see that there's collapsed lung, Atelectasis. We'd like to know about them recognizing that sometimes the tumor is distal and we can't fix them. But anytime that there's obstruction such that lung is collapsed is a good patient for us to see. There is some ideas that patients who are symptomatic and there's consideration of doing radiation or a therapy in the airway. There's some data that says that doing a stent or some sort of therapy in the airway upfront may actually improve survival in those patients. So we're looking for patients who have symptomatic obstruction, radiographic evidence of impingement on the central airways, for people who may be candidates for end of bronchial therapy in as an to additional therapies. That's really who we're looking for as our, as our primary candidates.

Dale Shepard, MD, PhD: When knowing that you're very, very innovative in terms of how you think about things. What do you see as the gaps as you see patients? What are the things that you say, if only. Like, what's the next step? Is it better materials? Is it better techniques? What's going to drive this field forward and improve our ability to take care of patients?

Thomas Gildea, MD: Literally all the above. So, right now we talk about rigid bronchoscopy that was invented in the late 1800s. We're literally talking about passing in stainless steel tubes to develop these devices. Really that's just material science. So, being able to deliver a piece of silicone into the airway requires that kind of devices. Certainly there is an opportunity to direct 3d print material that is much more amenable to implantation than what we currently have. Silicone technology, I love it's easy to work with. But we're using it because it was FDA approved and worked the system in the 1990s. Certainly there's things that we can do in that realm. The ability to put in implants that can not only provide structural support, that may be also able to deliver medication support. We could impregnate these devices with say, anti-infective material.

We can impregnate them with chemotherapeutic drugs. We can impregnate them even with low dose radiation delivery products, if necessary. All those things are theoretically possible, just based on the science instrumentation. I could build a stent in the airway without having to manufacture a week in advance. Theoretically, there are some ways that even the dentists put these devices in there and then turn on a blue light and polymerize things in real time. So when I turn my inventor's brain on, I can imagine pulling all sorts of interesting ways of building things in the body in real time and finding ways of delivering drugs into the airway, finding ways of making new materials work for us in different ways.

So the opportunities are endless when it comes to finding new and better ways to make airways work. And of course, if we even get into the really exciting stuff with term of regenerative medicine, taking and replacing entire cell lines, replacing mucosa, replacing cartilage, we still have no viable way of replacing the trachea. Tracheal transplant is really something on the science fictiony almost even the folks that have attempted have been very controversial. So the idea of doing a full tracheal replacement and replacing central airways, even after radiation or something, building back some of these structures can be done with regenerative medicine technologies and can do endoluminal. So really so many opportunities, so many things could be done. And it's just really chipping away at the iceberg. A way of thinking about these things, for me.

Dale Shepard, MD, PhD: What's the biggest challenge with the trachea? Why has that been so resistant to be replaced?

Thomas Gildea, MD: Well, it's a couple things when you talk about real estate. It's real estate's location, location, location, and really the trachea is a tricky thing. So it's in the middle of everything. So it's not really an accessible organ for the most part. And secondly, its blood supply is really tricky. So the upper part of the trachea is blood supply is limited. It comes from around the thyroid and then the lower part of the trachea comes off branches of aorta. And so the trachea is very prone to problems with blood supply. And so if you try to put a trachea or replace a trachea and you can't reattach a blood supply and it's under tension, it just breaks apart. And because of where it is, it lives in the middle of everything important. It's just been so notoriously different to figure out how to manage it. And so those are the the critical things. And there are surgeons who make a career out of managing trachea problems and I'm just happy to work alongside them.

Dale Shepard, MD, PhD: You mentioned some of the things that or possibilities to move the field forward. Are we doing research in any of those areas here at the Clinic?

Thomas Gildea, MD: Yeah. There are folks doing different things here. Mostly we're a clinical machine, but there are some surgeons, an ENT space. They're doing some interesting stuff. You know, we are working a lot around cancer diagnostics here and, but not so much into the basic science things in my field. There are some folks around the country that we try to establish collaborations with.

Dale Shepard, MD, PhD: Well, that's great. So Tom, you've provided some great insight in the area here today and we appreciate you joining us.

Thomas Gildea, MD: Thank you, Dale. It's really interesting stuff you're doing, and I appreciate the opportunity to chat.

Dale Shepard, MD, PhD: This concludes this episode of Cancer Advances. You'll find additional podcast episodes on our website, Clevelandclinic.org/canceradvancespodcast. Subscribe to the podcast on iTunes, Google Play, Spotify SoundCloud, or wherever you listen to podcasts. And don't forget, you can access real time updates from Cleveland Clinic’s Cancer Center experts on our Consult QD website at consultqd.clevelandclinic.org/cancer. Thank you for listening. Please join us again soon.