Thank you, everybody, for coming today to this session. We have a great cast here, Marie Boudave from Cleveland Clinic, Deb Levine from Stanford University, and I'll be talking from a surgical perspective from Baylor College of Medicine, Houston, Texas. Thanks a lot for joining us. I think this is clearly a very important topic in lung transplantation, and it's probably one of the most important things that we deal with, at least after the transplant. So we'll start with the first talk, which is going to be on perioperative aspects, and then we're going to go to Dr. Levine's talk that's going to look at how we can diagnose and identify CLAD early and novel, state-of-the-art elements of that. And then we're going to get into treatment with Dr. Boudave's talk. So I hope that at the end of this, you'll get a rounded-out sense of how we can identify and manage what is probably the most important complication right now in lung transplantation. So my talk, as I mentioned here, is Novel Donor and Operative Risk Factors Associated with Development of CLAD. I'm Gabriel Lohr. I work in Houston, Texas. My disclosures are shown there. Perhaps the biggest disclosure is I'm not an immunologist. I'm actually a surgeon, and I want to be an immunologist, so that's kind of a bad combination. But I've done a lot of work around acute and perioperative aspects of transplant and donor preservation, and the more I've done this over 10-plus years in practice, I've developed a much greater appreciation for us to understand the long-term implications of the graft. So chronic lung allograft dysfunction is the most formidable obstacle that we have to offering lung transplantation to more patients in need. If it wasn't for CLAD, we'd probably be offering transplant to many more patients who have advanced ILD, cystic fibrosis, if needed COPD, multiple forms of irreversible lung diseases. But because of CLAD and its effect on the long-term function of the allograft, we have to be a little bit more selective about offering transplant for people who are definitely going to benefit and how many years that's going to mean. CLAD, as you all probably know, affects an estimated 50% of patients who undergo lung transplantation by five years after transplant. CLAD is chronic lung allograft dysfunction. It's broadly defined as a 20% drop in their FEV1 post-lung transplant. After ruling out non-immune reasons. So largely we're talking about an immune-mediated event. There are some important surrogates to CLAD that I think we have to consider here, and that's when we look at the literature or what's been done, any research that's been done on this, a lot of times you're going to hear BOS, bronchiolitis obliterans syndrome. It's only recently that we really changed the definition full-heartedly to go towards CLAD in a very important consensus document from the ISHLT. But since it takes a while, like three to seven years to actually see this, detect this, it's important for us to look back at studies which have looked at BOS and survival even as some relative proxies or surrogates for what we understand as CLAD. So a lot of what I'm going to discuss here on the perioperative side, and I think that this is probably the least important talk here in this session, but what I'm going to be stressing is things that we do in the operating room or around donor preservation that may or may not heighten the recipient's alertness to this new foreign donor and all of the foreign antigens that this foreign donor brings with them. And whether or not that conceivably triggers a lifelong recognition of this organ and potentially increases the likelihood of having rejection down the line. So as a brief review, our immune system is broadly divided, in order for us to understand it better, by immunologists, it's divided up into two different aspects, the innate immune system and the adaptive immune system. The innate immunity are cells that are just constantly circulating, they're the first line of defense, immediately activated irrespective of MHCs or any compatibility issues. It's simply a reaction to damage, to stress. We now think that there are actual particles that activate this, I'll talk about this a little bit more, damage associated molecular patterns, for example. So innate immunity is very easy to activate and anything, for example, ischemia or reperfusion injury that comes with every transplant is going to activate the innate immune system. Adaptive immunity takes longer, so adaptive immunity brings in T-cells and B-cells to develop antibodies to launch a more sophisticated and prolonged attack on the organ. And this does require recognition of foreign antigens for the most part and foreign MHCs. So that happens down the road and that's likely what leads to CLAD as we know it. But there's, it's not difficult to imagine that there's crosstalk between these two elements as innate immunity tries to trigger adaptive immunity. So let's look at innate immunity and primary graft dysfunction. Primary graft dysfunction is what a lot of us, especially in surgery, tend to research. It's a very acute outcome, non-immune mediated, except for rather innate immunity is considered to be important for it. But it's not rejection, in other words. So primary graft dysfunction is edema that happens to the graft. You develop hypoxia. There's a disruption of the endothelial cell layer. Probably early on, a reactive oxygen species mediated event, you get some injury to the lining of the endothelial cells and circulating neutrophils that are always policing us in the body get activated, migrate into the lung, start causing immediate damage. But during this, there is a release of cytokines and signals to the adaptive network that comes later. So we looked at this a lot actually. This is just one representative study that showed that there in fact are a series of pro-inflammatory markers that are expressed very early on and are very predictive of patients who have primary graft dysfunction and different levels of primary graft dysfunction. You can see these elements here, IL-1RA. So a series of interleukins, chemokines, growth factors as well. And any of us that know anything about immunology, we know that these elements are precisely what then goes on to alert T cells and B cells to start doing what they're going to do down the road. We can see that there's some elements like IP10 that are elevated within six hours. Most of these are elevated within six hours of reperfusion. It's pretty striking in patients who develop primary graft dysfunction compared to those who don't. But you can see that the patients who don't develop primary graft dysfunction have a very flat curve. They're almost immune silent in many ways. So that's very intriguing. And if we look at apoptotic markers, we see that in people who develop severe primary graft dysfunction, these apoptotic factors start to grow slowly in the circulation, much more so than if they did not have primary graft dysfunction. So the Lung Transplant Outcomes Group has looked at this actually for a long time now with very elegant studies, a very large registry at the importance of innate immunity. It's actually formed the basis of our knowledge to date. So the idea that kind of collectively has branched into it, we have some of the members here today, so hopefully they can comment, but there's a fundamental signaling mechanism for a lot of these innate immune cells, which is the TOL-like receptors and NOD-like receptors. And what's striking is whether you take biopsies from the blood or from the tissue or from the BAL, you almost always see this increased TLR, NLR signaling in patients who develop primary graft dysfunction. And this is a very ubiquitous receptor found in many immune cells, and it leads to the upregulation of all of these genes that we saw in the prior slide, which was all the interleukins and the chemokines and the cytokines. So PGD definitely activates innate immunity. What binds to these TLR receptors? It's usually these damage-associated molecular patterns. They may be released when the endothelial cells are damaged at the time of ischemiary perfusion, and it's kind of a nebulous term here, DAMPs, but you'll hear about it a lot, and it's a lot of different compounds, uric acid, mitochondrial DNA, histones, parts and fragments of the cell. Basically anything that's abnormal and shouldn't be there has the potential to be recognized by TLR-NLR pathways. This study by UCLA was kind of interesting in 2016, and they noticed that even transient primary graft dysfunction, so that that comes in the first few hours and goes away, led to a substantial reduction in BOS-free survival. So already this was telling us that some elements of primary graft dysfunction definitely lead to this. And even prior to that, Whitson's group, while he was studying this at the University of Minnesota in 2007, saw similar findings. So patients with severe graft dysfunction had worse long-term outcomes in terms of BOS-free survival than patients that did not. And again, my hypothesis, this boils down to a lot of activation of these T cells that will then go on to recognize these MHC and foreign antigens throughout the lung. So these T cells are always circulating. They know that you have a foreign organ inside of you, but it's probably best for us to try to limit poking a bear, so to speak. So if you have these T cells and B cells out there that are already potentially going to interact, you're already keeping them at bay with ProGraft and with steroids and with CellCept. So if there's anything that we can do to limit exposure of additional damps that would heighten their alertness, it's probably a good idea. There are multiple potential injuries that can lead to this initial activation of the innate immune system, more so than just PGD, although some of these are implicated in PGD. So donor injuries, barotrauma, trauma, DCD organs that have some element of hypoxia, re-oxygenation, prolonged ischemic times, injury, infection. Several recipient perioperative factors, too, that we deal with commonly, such as whether we use extracorporeal support during the operation or not. As many of you know, that's a tubing, and blood goes through the tubing and can activate the innate immune system simply by blood going through a tubing to support the patient during the transplant. Prolonged ventilation, acute rejection, obviously pneumonia and aspiration are just some of the many potential injury sources that happen perioperatively that could increase activation of T-cells down the road. So I want to talk a little bit about extracorporeal supports, where we were looking at this earlier. So there's different modes of support that we use to conduct a transplant safely. This one is kind of the most invasive, if you will, but it was a very common one that we did up until maybe about less than a decade ago. So cardiopulmonary bypass used every day for heart surgery allows us to decompress the heart, delivers blood into a reservoir and a pump and an oxygenator, and then that blood is delivered back to the body. You can see it actually looks pretty complicated. That's because there's a lot of different tubings, a lot of different roller pumps, and not to mention there's a volume reservoir, which allows an air-blood interface. So there's a lot of potential for activating an innate immune response and circulating complement in the blood that is circulating through this on the way to the patient. There's also ECMO. So ECMO is much more commonly used now, mostly as a way of reducing bleeding because you need a little less heparin use. So it has some advantages. It's certainly a smaller circuit, it does not have the volume reservoir, and so there are some hazards where you may not be able to filter out air and things like that. But given that it's a much smaller circuit and no air-blood interface, it is conceivable that there's less activation of the immune system with it. The last option for doing these transplants, of course, is single lung ventilation. So if the patient comes for transplant evaluation early enough and has a contralateral lung that can actually function reasonably well during the operation, then we can actually very easily use the contralateral lung to ventilate as we implant the first donor lung. And then once that donor lung is implanted, we use that one to complete the operation. So this is also a very nice way to do it. And so we did a study within our group that was published just last year. But broadly speaking, it was 59 patients. We quantified cytokine release in three different groups, in bypass, in ECMO, and in no support. And we did notice that there was more graft dysfunction in the bypass group, and second most was in the ECMO group, and then the smallest was in the off-pump group. But this is a small cohort. But what was interesting is that we also saw that the bypass group had a lot more endothelial damage, as evidenced by angiotensin 2, angiotensin 1 ratios. And then both bypass and ECMO had similarly increased amounts of cytokine activation. And so both extracorporeal support devices and ischemia reperfusion injury as well likely lead to release of DAMPs that then activate these TLR receptors and cause increase of pro-inflammatory cytokines. So as you can see here, IP10, this is one of the chemokines that we saw very importantly with primary graft dysfunction. This was substantially elevated in the bypass group and in the ECMO patients, and pretty immune silent in the off-pump groups, which was interesting. We thought was interesting. The MIP1 beta had a similar pattern and interleukin 1 RA. And then this shows our endothelial cell markers that show greater, a more deleterious ratio in the bypass serum than in the ECMO or the off-pump patients. So this gave us a little bit of a glimpse that it is possible that some of the choices that we make related to extracorporeal support in the operating room may or may not translate into increased immune activation and potentially downstream activation of T cells. I wanted to look at this a little bit more. This is not published yet, but it's a small cohort of complete CLAD data from our institution. It had 108 patients in this. Our coordinators put this together. All double lungs, excluded singles, and excluded redos. What we noticed here is that our bypass cases had, in fact, the worst survival overall. And then when we looked at CLAD-free survival, it was the same thing. So the bypass cases seemed to have a little bit more graft dysfunction in the front end, but also in the long-term. Interestingly, and this is still too small of a cohort, we're flushing this out more, but the ECMO group seemed to do the best. So that was encouraging. It was a fair number of ECMO cases. So perhaps that smaller circuit is advantageous. There was no difference here between these two right now. So we're going to have to add more patients to flush this out. But these kind of studies are challenging to do because you're looking at early events and CLAD. So you have to either wait for five, six-year follow-up, or you have to look really meticulously at cohorts, earlier cohorts that you have. Interestingly, acute rejection followed a similar pattern. So the bypass had the highest number of acute rejections, followed by ECMO and off-pump being fairly similar. So again, are we doing things that are poking a bear here a bit and getting these T cells a little bit more alerted to the fact that we have a foreign organ inside of us? And if we are, then it's important for us to identify these and, within reason, try to alter them whenever possible. So we looked at PGD a couple of other ways, too. So this was severe PGD resulting in tracheostomy and found that, certainly in those cases, also there was a substantial reduction in BOS-free survival. So these were cases that had PGD and a trach for prolonged ventilation, so kind of a very sensitive marker for truly impactful PGD. And this matched what we had seen earlier with Witson's data as well. Interestingly, in our institution today, and we look at PGD scored with the most updated ISHLT scoring system, we don't see a difference in long-term survival. And it's possible because there's different grades of PGD. There's probably no two PGDs that are probably identical to each other, or we're getting better at treating them. So there's a lot of different options here. However, when we looked at CLAD-free survival, we did see the same thing where we saw transient PGD making the CLAD-free survival worse. But interestingly, severe PGD was similar to no PGD. So I think that the verdict is still out. And this is where we may have to turn to biomarkers. So this was a nice study by Keller and colleagues that basically showed that if you had patients that had PGD and had CLAD compared to patients that had PGD and did not have CLAD, the ones that had CLAD had greater release of cell-free DNA, perhaps a proxy for damage-associated molecular patterns. So I do believe that probably we're going to need to have better molecular biomarker readouts for PGD. This was a study by Dr. Bharat in Chicago showing that there certainly is plenty of potential for an immunologic link between PGD and CLAD with several of these markers that up-regulate T cells. Interestingly, he found that in PGD cases that activated HLA-2 antibodies, these were the ones most likely to proceed to CLAD. So there may be specific subtypes of PGD that become more important for downstream development of CLAD. Now, very briefly, EBLP is something, obviously, that is being done a lot. That certainly is a circuit, and it's using a lung in a circuit. So there's a lot of different considerations. Whether it increases inflammation, or maybe it washes out the inflammation, maybe extended criteria donor lungs that were transplanted, maybe that's bringing in more CLAD potential, or maybe this is an opportunity to immunomodulate. So this was a study out of Toronto, very extended criteria donors in the EBLP group compared to the no-EBLP group, and they saw no difference in CLAD. So that was very encouraging, obviously. And they also saw no difference in DSAs. And this is a practice of fairly extended criteria donors. This is data from our group showing the portable normothermic organ care system, early reduction in primary graft dysfunction, and no difference in BOS-free survival at the very end in five years. So certainly not making BOS worse. And if anything, maybe there's a trend that it's making it better, which is interesting and I think is going to require a lot more study. This is our extended criteria study, the EXPAND trial, using DCD donors, low PF ratios, et cetera, very high utilization in this trial. And as you can see that the BOS-free survival, the incidence of BOS was actually quite low in this extended criteria cohort compared to a standard ICE comparator historical control. That was evident at three years for sure, a little less evident at four years. But it is interesting and a little counterintuitive that EVLP doesn't make the organ perhaps a little bit more immunologic. We looked at the increase in cytokines at six hours after reperfusion and found no differences between EVLP and non-EVLP. And this is a look at extended criteria donors, looking at a donor discard rate. So donor discard rates at the very far end are the most extended. And when you saw transplants that used those, the five-year mortality was pretty similar to the ones that had lower discard rates. So either extended criteria organs on EVLP or extended criteria donors across the board don't seem uniformly to be contributing to increased rejection. And this is interesting aspect of perioperative stuff also. This is the bronchial artery revascularization. We don't typically revascularize the bronchial artery in transplants because it's a challenging kind of thing to do, requires full bypass support. But when it's done, clearly the organ has less ischemia up front. It has a more complete circulation. And when you look at complete bronchial artery revascularization compared to incomplete, there's a trend towards less bronchiolitis obliterans. So it's something I think we'll also have to take a look at in terms of perioperative factors that we might be able to have an impact on. I'm going to skip through these. So perioperative insults are likely to have an effect on the occurrence of CLAD. There are trends supporting a positive correlation with primary graft dysfunction and cardiopulmonary bypass use, potentially a negative correlation with EVLP or an inverse correlation with EVLP in bronchial artery revascularization. Perioperative factors may play a role, but the signal has not been consistent. I think this is going to require further study. I think there's an urgent need to look at early biomarkers that we can use as readouts. And if we identify these early biomarkers for CLAD, we should look at trials to reduce those so that we can hopefully impact CLAD on the long-term basis. So I'm very optimistic that we're going to start making a good impact in this to increase organ availability. And thank you very much. Thank you. Thank you, Gabe. That was beautiful. I'm going to grab my mic. That was a beautiful talk. Now for something a little more clinical. Let me just try to get this. And today, thank you to Gabe and to Chess for inviting me to talk about chronic lung allograft dysfunction, getting to the diagnosis. So I have no disclosures. But if you didn't hear this this morning at the AMR talk, if you find yourself on the windward side of the island, you have to try to get to Kailua Beach. Kailua Beach is the biggest kite surfing beach in the world and probably one of the most beautiful, if not the most beautiful beach. So if you can get over there 20 minutes away on the H3, you can do it. You've all seen this slide before multiple times for a long time. But I think it's always important to start where we have success. And I think we can all congratulate ourselves internationally for the increase or the exponential increase in numbers we've had over the last 10 to 15 years. Unfortunately, we haven't seen the same success in really changing our outcomes over the last couple of years. And what's that secondary to? Well, it's a clad session. So we're talking about clad. Chronic lung allograft dysfunction is the primary reason for graft failure as well as patient morbidity and mortality after a year. So how did we get here? And I think I want to take a little journey of how we got to clad and where we are now. So let's take a step back. I'm gonna move this over. Transplant, when you start looking at 1960s when the first transplant was done by Dr. James Hardy, that patient really didn't live long enough for us to evaluate whether he had clad or not, right? He only lived two weeks or a little less than two weeks. And he died really from infection and renal failure. His lungs were actually pristine after he died. It was about 10 years later or a little bit less when DIRM showed one case study of a patient who lived 10 months. And at six months, he started to decline significantly. When he did the autopsy, they saw that he had this weird looking pattern called obliterative bronchiolitis, which really by chance had just really been introduced to the pulmonary world in itself. So it was pretty intense. It took about another eight to 10 years when two more authors, I think we all know Dr. Alan Glanville and Dr. Burke, who really put out larger case studies looking at this weird pattern of patients who had done poorly and died. And these were autopsy studies. I think Burke had four patients, and I don't know what happened to the slide. You missed the actual graph. And then on Dr. Glanville's, he had way many more. Tazilar was a pathologist, and he adjudicated all of this work by looking at multiple patterns and finding that BOS or obliterative bronchiolitis was the main reason. A few years later, Kramer said, hey, you know what, looking at all these patterns, it's pretty patchy, and it's heterogeneous, and it's not gonna be easily identified by bronch. So he put in the idea that we all know that bronchs and transbronchial biopsies are not the best way to evaluate patients with bronchiolitis obliterans syndrome. Same year, Dr. Cooper finally did a working formulation for the nomenclature of chronic lung dysfunction. And that really led to Dr. Etienne's work in terms of the first update on BOS and some of the really good work in terms of updating both the classification as well as the severity score. It was a few years later that Conan and Packel really started to look at this new thing of upper lobe fibrosis, and where are we going with that? Is it really chronic dysfunction? Is there something else going on? And it was Vierlinden in 2014 who identified the new classification system of chronic lung allograft dysfunction, or CLAD, and really incorporated these different types of phenotypes. And in 2019, both Vierlinden and Glanville brought us to where we are today, with Vierlinden giving us the classification and criteria for the new CLAD criteria, and then Dr. Glanville and his group who really spearheaded the RAS, or restrictive allograft syndrome, that really probably was starting to get known in the early 2000s. And so that's where we are today. How's it going? How's the criteria going for all of you? I think we are doing well, but we probably still have some things to do. So let's start with just the clinical definition. And what is CLAD? CLAD really has a spirometric, as Dr. Lohr had told us, a spirometric definition. CLAD means that you have a decrease in your FEV1 below 20% for a length of over three months. And that sounds pretty straightforward, right? You just find a point where it goes down 20%, once for three months, and then you have the diagnosis for CLAD. Pretty easy. But let's take it step by step, because it may not be as straightforward, and there may be areas that we can work on in the future to find out how we can identify CLAD a little bit earlier. So let's start at the beginning, when you're first seeing a patient, and you drop your FEV1 by greater than 10%, what do we all do? We all look for causes that could be causing that. And there's many. There's so many causes. But really what it's done for, it's trying to exclude causes other than CLAD. So really we're not asking, sorry, we're not asking what is CLAD. For this part, we're asking what isn't CLAD. And they have a whole list of things and a list of etiologies that really are not included in the CLAD definition. And those are the usual suspects. We all know what they are. Pneumonia, effusion, weight gain, acute rejection, frailty, and even plural effusions. And there's many more. But these are the things that we all do. This is our day-to-day life. We want to rule those out so that we could eventually, possibly rule in CLAD as early as possible. So we have what's there and we have what's not. And we say, hey, we've got to figure out what to do with this drop in greater than 20%. And you have to find it from the reference value baseline. I think an author from a while ago showed us this is very difficult. Sangeeta Bharade did a little project that looked at how we all look at where our baseline is and how the trajectory goes for CLAD. And it's still, it's not easy to say that it's easy, but it's not as easy as we think. So, for example, what is the baseline? What's the reference level? What is that? Well, maybe on something like this, it may be easy to find that. But then you look at what it really means. And what you're talking about is the baseline means that it's the mean of the two best post-operative FEV1 measurements taken greater than three weeks apart. So we have the definition. So now we talk about, okay, we have a baseline. We have everything else that's excluded. And then how you decide the level of certainty of this progression of CLAD is based on time. If it's less than three weeks, you might have it possibly. If it's greater than three weeks, but less than three months, you probably have it. But if it's greater than three months and you've ruled everything out, then you have definite CLAD. And once you decide that, you then start adding other platforms like CAT scans and the total lung capacity to kind of evaluate the different phenotypes of CLAD. And remember, we know now of two major phenotypes, both CLAD and RAS, and we know that CLAD is, I mean, BAS and RAS, BAS being the more common, up to 60 to 75%, and RAS being the least common, but probably more detrimental. And we also know, sorry, that there's multiple other phenotypes, both the mixed and the undefined, but probably even more. So what about severity? Is everybody the same? So I have CLAD, you have CLAD, we all do the same thing? No, I think back in 1993 and again in 2001, basically they knew that we have to grade it in terms of severity, and that's what they did, both for Kramer starting in 1993 and Etienne, adjusting that and adjudicating that there may be a role for something called BAS OP, so that we, or 0P, so we can really start identifying it earlier, because at that point, we know that we have to start treating. So in 2019, obviously, the name changed from BAS to CLAD when we decided that CLAD was the overarching title, including BAS, and they took out the OP, but they added a more severe score of less than 35% of CLAD-4. So we know kind of where we are when we're differentiating. More for patient, or actually center-to-center research projects, rather than just paints the severity of patient has a 36% FEV1, there's probably not gonna be clinically as much importance as someone that's less than 35. We know they're doing poorly, and maybe this is a point we'd say, hey, in a clinical trial, this person is way too far into the irreversible stages. So this kind of helps us to decide when we're talking about setting up studies together, and what severity we wanna look at, and I think that's important when you start talking about the heterogeneity of this syndrome. So I don't know if anyone's gone to HANA, but it's a pretty rigorous drive, and some people think it's beautiful there, but it might not be worth the drive, so I don't know if you guys wanna go there or not, but diagnosing CLAD, why isn't it always straightforward? I mean, it seems like it should be, but why isn't it? Number one, CLAD is identified spirometrically, right? It's a diagnosis based on spirometry. There's so much bias that we can see on that. Number one, there's a fluctuating baseline. Look at this, where's the baseline on either of these? I don't know if you guys can raise your hand, but basically that's subjective, it's not objective. We have, I mean, person to person, center to center, we misinterpret or even kind of just re-adjudicate the definition and data every time we see a new patient. Then there's the people who just never did well. They never gained that adequate FEV1. How do you look at them? They might have an FEV1 of .9, and then they have a .8 and .6. What does that even mean? I mean, it's not truly something that we can really evaluate. What about the patients that just can't do PFTs? They can't, they have a trach, they can't, you know, they're not PFTable, I guess. And then there's always these other diagnoses that we can't exclude, they're kind of mixed together and they're concurrent, so how do you adjudicate them? So there's problems with the actual definition because it's based on spirometry. Number two, and probably most important, is that CLAD is a diagnostic heterogeneous syndrome. It is not one disease. So it's probably the most untalked about, unappreciated challenge that we have, but it's clinically, functionally, and likely molecularly heterogeneous, and it's not one distinct disease, and I think we all have to realize that when we're doing studies, when we're trying to think about therapies, and when we're trying to see patients daily. Clinically and functionally, it's definitely a heterogeneous system. I mean, if someone drops their FEV1 from 4.2 to three, they're gonna be clinically different than someone who drops from 1.2 to .9, even though they may have the same drop. They both have CLAD, but the guy up on top, he's probably going, running a marathon, with the guy on the bottom, that little bit of drop is going to really make his life significantly worse. So clinically and functionally heterogeneous, but of course, we all always know, also know, sorry, that it's pathologically or histologically heterogeneous as well. So both RAS, BOS, and probably everything else in between. What a difficult syndrome to diagnose. You know, you have CLAD, I have CLAD. We're different. This is a different process for every patient. So CLAD, again, clinically, pathologically, and functionally heterogeneous, and a syndrome that's heterogeneous, I don't even know if I said that, heterogeneity, is challenging, both in identifying and diagnosing the disease. So first of all, who has it? But also, it really gives us a huge challenge when we're trying to study the disease, and when we're trying to treat. There's probably numerous studies that show that the therapies have not shown benefit. Well, if you had someone way back there with the 0.9, and then someone with the 0.3, all mixed together, you're treating them the same way, and adjudicating that data the same way, it's gonna be no benefit, because you're not really finding who can benefit and who can't. We're mixing everybody together. So added to this difficult situation is the fact that phenotypes are great, but our patients have phenotypes that are both distinctive and shared. So they have both. They're not like, totally, this is BAS, this is RAS. They share certain criteria, and they also are different on many features. So it makes it even more, in terms of looking at more difficult, and looking for prognostic manifestations, as well as how they will do over time. So these and other diagnostic challenges really limit us identifying CLAD early, and just like Gabe said, that's probably the most important thing, not just to treat, but also to kind of develop the risk stratification, and introduce some of these therapies that we need so badly. Because of that, there's a strong motivation to help develop new diagnostic and predictive tools, and platforms to identify each phenotype. These platforms can be one of many. Radiographic, meaning CT scans, whether it be some of these new volumetric, or functional CT scans, or MRIs, or some of this new phase-resolved functional perfusion scan. All of these things are becoming interesting to us, because we know that if we can find some difference between a subset of patients, we may be able to identify that subset patient earlier, and start to treat. So radiographic platforms. Other diagnostic platforms that don't really fit into anything special, this electronic nose looking for CLAD that's been looked at a few different places, as well as this whole thing with methacoline challenge, and looking at even oscillometry. There was a lot on oscillometry at ISHLT last year, and it was very interesting that just looking at the tools we have, we can actually start kind of identifying areas that we can make them better. So radiographics, PFTs with methacoline. I don't know about the electronic nose, that's kind of a new platform. But really before we start looking at some of the things that we are looking at in the near and distant future, and those are definitely increasing in time. Increasing numbers of platforms, whether it's radiographic, histologically, molecular, serologically, or cellular. There's a lot of things coming up the pike that are so important for our patients to get, to be adjudicated, to be actually used clinically, as well as in research. Sorry about that. Thank you, thank you so much. Anyways, several of these are almost ready for prime time, and I think this is so exciting for us. I think in the last three to five years, we have so many things that are opportunities for us to move into. And I think the next generation of transplanters is so lucky they're gonna have way more than radiographics and histology, and maybe even DSAs. So I mean, and that's, you know, I love DSAs. You guys know that, so that's something. But I think that's where we're going, and I think that's where we have to focus our attention. One thing that's important to know, though, is that there's not one of these strategies that's gonna work. It's going to have to be really a combination of these. I mean, you may be able to find an increase in injury, maybe with cell-free DNA or something else, but how do we know what that injury is? We have to bring technology together, as well as some of these platforms, so that we move together in one direction. And maybe someday we will have that drop of blood that has everything in it. So getting to the diagnosis. This has been a clinical talk, but it really shows us areas that we have to work on in each area, because getting to the clinic is where it ends. This is where we are helping patients day-to-day. But we're not quite there yet. We're close, but just like Dr. Alan Glanville always told me, step-by-step, we're gonna get there, adding to the 50 years of CLAD exploration, even if you're trying to get to this windy road called CLAD. And one more thing is this is a cute little cartoon. So you're gonna have to change to fit into the system, and these guys are saying, no, how about you change the system so we can all fit? And UNK is unknown, because there's so much still unknown that isn't gonna fit into our own system. So I thank you so much. Good morning, everyone. Why don't we go ahead and get started. Welcome again to this session. I wanna begin by first thanking the organizers and the society for the opportunity to present today. Over the next 20 to 21 minutes, because I timed this out exactly, I'll be talking about the therapies and the various therapies that we have for the treatment of chronic lung allograft dysfunction. I have no conflicts of interest or financial disclosures in relation to this talk, but I will be discussing several pharmacological therapies that are not FDA approved for the use in lung transplantation. This is our agenda for today. It's quite robust, so we'll go ahead and get started. In Dr. Levine and Dr. Laura's lectures, this audience can recognize, and many of you are transplanters, that chronic lung allograft dysfunction or CLAD is the Achilles heel of lung transplantation. And really, our treatment therapies in 2023 are quite limited, and I'll go into that in quite a bit of detail over the next few slides. This slide, I think Dr. Levine shared with you, and I think I wanna remind the audience that lung transplantation has the highest incidence as well as chronic rejection among all solid organ transplants. And therefore, the long-term outcomes in lung transplant recipients remain inferior to those of other solid organ transplant recipients due to the high incidence and rate of CLAD that's present. Except, I have to say, small bowel transplants have worse outcomes, so we're still above them. So if you look at registry data, and at five years, you can see post-transplant, 50% of lung transplant recipients will be diagnosed with a BOS phenotype of CLAD. And in fact, this diagnosis of BOS-CLAD or this phenotype of BOS-CLAD remains the leading cause of death after a lung transplant at one year. Now again, in 2023, our CLAD treatment options are actually suboptimal. I'm not gonna come up here and tell you I have a definitive treatment for CLAD. In fact, the reason why our treatments remain suboptimal is because we don't understand the definition of CLAD. We need a better definition. But more, the trials that we've had in place for various treatment options have been really poorly constructed. These trials are poor quality. There are many retrospective studies that are single-center studies. Many times, they don't even have a comparison or a control group. So our goals for the treatment of CLAD in 2023 are actually quite modest. We're hoping just to stabilize lung function. We really don't have a cure for CLAD. I'll talk a little bit about re-transplantation and its role. But again, in 2023, our goal is to stabilize lung function and to try to keep FEV1 as stable as possible without further loss. Dr. Laura talked about some of the risk factors that lead to the development of CLAD. But when you have a patient with established CLAD, it's important to come back and look at several risk factors that are listed here. And some of these risk factors look at reduction in treatment of viral or bacterial infections, updating immunizations, readdressing prophylaxis for CMV and preventing CMV breakthrough, especially in specialized populations such as the short telomere patients. And this was discussed at the symposium yesterday by Dr. Patel. Also, maybe it may include the introduction of cyclical antibiotics in hopes to reduce bacterial colonization in patients and readdressing GERD management, whether it's pharmacologically or based on a patient's FEV1, if they could tolerate surgical intervention or if they would benefit from a non-surgical approach. But these risk factors need to be addressed. The point is to reduce lung inflammation and therefore mitigate loss of FEV1. Let's say a few words about re-transplantation. This is really reserved for a small population of patients that are suffering from end-stage CLAD. In fact, if you look at registry analysis, only about four to 6% of reported re-transplants make up the total number of transplants in the registry. Most transplant centers or a limited number of transplant centers offer re-transplantation to their recipients who are suffering from CLAD. Ed Cantu and the group from UPenn looked at the ISHLT registry and found over 1,500 re-transplant recipients from a time period of 2005 to 2017. What they found was that the one-year survival in this cohort of re-transplants was about 74%, and this survival was inferior to primary transplants at all significant time points. 43% of this cohort had BOS as the primary indication for re-transplantation, and if you actually look at the Kaplan-Meier curve on the right-hand side of your screen, you can see the outcomes in this population. BOS as a phenotype indication has actually had better outcomes compared to other indications for re-transplantations such as RAS, airway dehiscence, or acute graft failure. Now, let's switch from the surgical therapies and talk about some of the medical therapies that are available. Probably the most famous drug or the most popular drug that's been used to treat or prevent BOS is azithromycin. Everyone in this audience knows azithromycin is a macrolide antibiotic. It reduces airway neutrophilia and decreases inflammation through several different pathways. The long transplant community was introduced to azithromycin as a possible therapy for chronic rejection or established BOS in a pilot study back in 2003. It was only six patients that were studied. These patients had a drop in FEV1, had established what was called BOS at that time, and azithromycin was instituted three times a week and showed a subsequent improvement in FEV1. About a decade later, there was a meta-analysis consisting of about 10 observational studies on 140 patients. In seven of these studies, there was an overall mean increase in FEV1 of about 9% in patients that were treated with azithromycin. The Newcastle group with all cores actually conducted a retrospective control or randomized control trial in 2015 and 46 patients that were either randomized to placebo versus azithromycin. In nine out of 46 patients, there was an improvement in overall FEV1 of approximately 10%. And again, this was in the group that was treated with azithromycin. There are several other studies out there looking at azithromycin as a treatment for chronic rejection, especially the BOS phenotype. These studies, as well as the studies that I shared with you, led to the 2014 ISHLT guidelines to recommend azithromycin be instituted for at least three months in patients that are diagnosed with the BOS phenotype of CLAB, irrespective of what their BAL shows in terms of cellular makeup. Another drug that's gotten a lot of attention in terms of treatment for chronic rejection is a leukotriene receptor antagonist, Montelukast, which is used in the treatment of asthma. The first pilot study that was looked at Montelukast consisted of 11 patients in 2011. These patients had established BOS. They were on azithromycin. And with the addition of Montelukast, there was a decrease in the FEV1 decline in these patients at a six-month time period after treatment was initiated. There was also a single center randomized control trial of 30 patients that had late onset of BOS. They were randomized to either getting placebo or Montelukast. There was no effect that was seen on decline of lung function in comparison to the pilot study that I described a few minutes earlier. But interestingly enough, in a subgroup analysis at six months, 50% of patients that had early BOS, BOS stage one, saw an improvement in their FEV1, and no improvement was seen in the placebo group. Now, in terms of standard immunosuppression, what do we know about standard immunosuppression and what we use, and how does that treat BOS? Well, there isn't a whole lot of evidence out there. I'll tell you, when I was a fellow, there was this practice of conversion. I think some of you are about the same age as I am. But this was where, no matter what sort of immunosuppressive regimen you were on, we just switched to another regimen. So if you were on cyclosporine, you went to Tacro. If you were on Tacro, you went to Cyclo. And there was no evidence for this, but we did it. This has fallen out of favor. And it's clear that we don't have any randomized control trials to evaluate the efficacy of substituting Tacro for cyclosporine to treat BOS. But we do have randomized control trials looking at Tacrolimus and showing that Tacrolimus is superior to cyclosporine in the prevention of BOS, but not in the treatment of BOS. We do have several case studies out there that show conversion from cyclosporine to Tacrolimus may reduce or slow down the decline in overall lung function. But we don't have a whole lot of robust data out there that I can actually share with you. Well, now I'm gonna talk about some of the immunodepleting therapies that we have out there. I'm gonna talk about allotuzumab, ATG, and total lymphoid irradiation. So these are many times referred to and called salvage therapies or augmented immunosuppression. The studies that are out there are not robust. They're quite limited. Many of these studies, if they're prospective, they don't even have a control group. Now, I would caution you, when you're looking at these salvage therapies or thinking about using them in your patient, be careful of the risk-benefit profile. Again, the risk profiles are substantial with some of these drugs. And if these therapies don't work, and for example, you're gonna look at retransplantation for your patient, you don't wanna have an infectious barrier or an issue with CMV that may become an issue that you can't control, limiting this patient's access to retransplantation. So again, be very careful when you're looking at these salvage therapies or considering using them. Now, the first salvage therapy I wanna talk about, which is commonly used across the country at various transplant centers, is ATG. There is a single-center study, which is probably the landmark study, although there are several other studies looking at ATG, but this single-center study looked at 71 patients with established BOS phenotype. Now, these patients received ATG, and 23% of the patients improved or stabilized their FEV1. 40% of these patients had an attenuated FEV1 decline. However, 37% of these patients continued to have a worse decline in their FEV1. So this is a study that many people actually refer to when they consider using ATG as a salvage therapy. There are several centers in the United States that are starting to use alituzumab as a salvage therapy, and the first time we heard about alituzumab being used this way was actually back in 2007. In 10 patients that had established chronic rejection or BOS at that time, these patients all failed increases in steroids or pulse doses of steroids and ATG. When these patients were given alituzumab, they had a transient increase. Seven out of 10 patients had a transient increase in their FEV1, but no improvement in their long-term outcomes. Our largest experience with alituzumab comes out of UPMC and Chris Anser and his group, wherein 51 patients with early BOS, they were given alituzumab and showed stabilization, if not slight increase in the FEV1. But in this cohort, there was a really relatively large incidence or high incidence of infection. The group from the Brigham actually looked at three patients with short telomere and BOS, and they were given alituzumab in attempts to stabilize lung function. In this very small cohort, there was no increased incidence of infection like we've seen in the Anser cohort, but this cohort did not benefit with the administration or with alituzumab being given. And in fact, this cohort had significant evidence of cytopenias requiring transfusion as well as hospitalization. A few more words about alituzumab. If you look at the studies, it seems that alituzumab administration attenuates lung function, and it may actually work better in the BOS phenotype patients, but I'm gonna share with you two other studies. But one thing about this statement, I want you to keep in mind, it's not clear if this is just the course of BOS that we're seeing, or is this the direct effect of this drug. Again, these studies are quite muddled, they're quite dirty, it's difficult to draw some conclusions. But sustained results have been seen in two studies using alituzumab. There's a study that looked at alituzumab versus ECP for CLAD. In both groups, the FEV1 decline was diminished, but in the alituzumab cohort, this was very beneficial in the patients that had RAS and had a rapid decline in FEV1. And this was better than seen in the ECP group. In the alituzumab group, there was no increased infection that was seen compared to the ECP group, but overall survival between the two groups was the same. In another study that came out several years ago, in 14 patients with advanced CLAD, this is stage two and three CLAD, alituzumab was administered, and subsequently at one year, in these patients that had advanced chronic lung dysfunction, they had a 64% survival and stabilization of FEV1. So there might be some role for alituzumab in these patients that have more pronounced or more advanced chronic lung allograft dysfunction. Now a few words about total lymphoid irradiation, or TLI. It's best known for its treatment in cancer therapy. This is a therapy that's not often used in the United States, although certain centers have tried using this. It's more commonly used in the UK and Europe. It has a very strong immunosuppressive impact when it's used, and it's very long-acting. And sort of the manipulation of immunosuppressive drugs can be difficult with this therapy as well. Patients can develop bone marrow suppression, holding of anti-metabolites may be necessary. There may be an increased risk of infection. We don't have a whole lot of data about TLI. The data is quite scarce, but what we have seen that it may be effective in the treatment of both phenotypes RAS and BAS, and that it actually may be very effective in those patients that have a rapid decline in overall lung function. We learned about this therapy back in 1998, but the most recent studies, because these old studies were not very favorable back in the 90s, the most recent study published in 2022 has shown that there's a significant attenuation of the FEV1 slope in patients that are both rapid and slow responders. These are RAS and BAS phenotypes. So keep an eye on TLI. It's not really widely available. Insurance is difficult to cover this. Again, it's mainly used in Europe and the UK. I want to talk a little bit about the immunomodulating therapies that we have, including methotrexate and cyclophosphamide, also the mTOR inhibitors and the ECP for the next few minutes. So methotrexate, along with cyclophosphamide, are therapies that have been around for quite a long time, decades. Now, interestingly enough, methotrexate, we don't have a whole lot of evidence about it. We have some single-center studies that have shown stabilization of FEV1, but in these many studies, there has been discontinuation of the drug at pretty high rates due to GI intolerance and leukopenia as well as fatigue. But there is some evidence now and recently we've noticed that methotrexate may have some anti-inflammatory effects via the inhibitor of JAK1 STAT pathway. This may be a less expensive alternative to JAK1 inhibitors that I'll talk about in a few minutes and Dr. Diamond has a lot of experience with who's in the audience today. Cyclophosphamide is another drug that's been around forever, and we have some case series that have looked at cyclophosphamide and its use in chronic rejection and treating chronic rejection. We only have most recently a case study that was published in 1999 in seven patients that showed an improvement in FEV1 in 86% of the patients in this clinical trial and lung function stabilized. But the role of both methotrexate and cyclophosphamide are quite limited in the treatment of CLAD. The mTOR inhibitors, specifically sirolimus and everolimus, we have two clinical trials that have showed that they may have some benefit in the treatment of CLAD. Cahill et al. looked at 12 patients where mTOR inhibitors were initiated for CLAD therapy. They found that it was most effective, the mTORs, in the patients that had rapid lung loss, leading to stabilization of their FEV1 and slight improvement. In another clinical trial of 26 patients that had 10 of these patients having the phosphine type and seven of them having the RAS phenotype, when they were switched to everolimus and followed for a year after initiation of therapy, they saw that the RAS patients really didn't benefit. They continued to lose lung function. But the BAS patients continued to have an FEV1 improvement and showed stability at six months. There's really still, we're not at the place for clear evidence that mTOR inhibitors should be used in the treatment of CLAD, but this is something to keep in mind. Now, I want to say a few words about ECP. It's a leukotheresis-based immunomodulatory procedure. I think most people in this audience know how ECP functions or how we perform ECP. It is not FDA approved for CLAD after lung transplantation, but it has other FDA approvals. It is not reimbursed by most insurance companies in the United States and worldwide, and therefore it has limited some of its use. We don't know how long it takes ECP to work. We don't really know, if you stop ECP therapy, how long the effects of ECP will last. There are many questions we have around this therapy, including how does it really work and what's the mechanism of action, although we suspect it has to do with apoptosis of the lymphocytes. Because we have all these questions, up till recently, we had no randomized control data that was available to answer some of our questions, but I'm happy to report to you the CMS multicenter RCT study did end at the end of 2022, and those results are currently pending. We do have several observational studies that look at ECP and the outcomes from ECP. These are non-randomized studies, but they showed a decrease in FEV1 decline and improved survival in certain studies, but this response was quite variable depending on the study that you were looking at. We did learn from these observational studies that if you developed BOS greater than three years out from transplant, or if you had RAS, or a drop that was rapid in your FEV1, or you started ECP very late at your BOS stage, you would have a worse response to therapy. But I'm hoping this randomized control trial that just concluded from CMS will actually show us and answer some more of our questions. Now, in terms of future therapies that are out there, I want to share with you, we are getting a lot of information, and we're sharing a lot of information with our hematology colleagues. There are many similarities between CLAD, the BOS phenotype, and chronic graft-versus-host disease, and the drug I want to talk about from this list that I shared with you is tocilizumab. It is an IL-6 inhibitor. It prevents biting of IL-6 to its receptor, and it inhibits downstream JAK-STAT signaling. There are several studies in graft-versus-host disease that show that it is effective in the treatment of graft-versus-host disease, as well as prevention. There is a case report in lung transplant in a recipient that had a COPA mutation and developed CLAD and had stabilization of their FEV1 with tocilizumab therapy. Boston recently published an abstract of nine patients that received tocilizumab therapy for the treatment of CLAD, specifically the BOS phenotype, and it showed treatment in these patients that were treated. They had stabilization of their lung function at three months. Now, a few words about the JAK inhibitors. Dr. Josh Diamond had actually presented this data in 2022 at the ISHLT meeting. Josh is right back there if you want to ask him more questions, but this specific JAK1 inhibitor was studied in 23 patients that had a BOS phenotype. Our center actually was a multi-center study, and this specific JAK1 inhibitor resulted in stabilization of the FEV1 and had an absolute increase of 10% that was seen in 22% of patients. The phase two study has now been completed and the extension study is underway, so we'll have more data regarding the use of JAK1 inhibitors. A few words about inhaled liposomal cyclosporin A. You can never talk about a treatment for BOS without including this. This is a nebulized CNI therapy. We have had prior studies and a randomized controlled trial including 21 patients that showed stabilization of the FEV1 and FEC, but ongoing decline in the control group in this study. The Boston 1 and 2 trial, which was an international randomized controlled trial, multi-center trial, completed and closed in spring of 2023, and we're awaiting results from that study. Few words about perfenadone and nitindinib, our antifibrotics. We have several case series that have now been published looking at perfenadone in the RAS phenotype and that it actually attenuates the drop in FEV1 and FEC decline. The European trial looking at perfenadone has just recently closed and we're awaiting data from that trial. I want to say a few words about other future therapies including metformin that has been looked at in rat models and mesenchymal stromal cell therapy, which is currently going through phase three trials. Now I'm going to close with a suggested algorithm for the treatment of CLAD. After you've diagnosed CLAD as you were instructed by Dr. Levine and her excellent talk, you then want to look at the optimization of immunosuppression in your patient. You want to look at their immunosuppression levels. You want to make sure they're not super therapeutic. You want to make sure they're not sub-therapeutic. You may consider changing immunosuppression, especially going from cyclosporine to tacrolimus and azathioprine to mycophenolate. The role for pulse dose steroids in patients that are showing a drop in FEV1 is quite controversial and still people do it. They get to do a bronchoscopy, look at transponkyl biopsies and there's no evidence of infection or rejection they will go ahead and pulse patients because there's something to do and hopefully they can attack or target some sort of inflammation in the lung. So this is still controversial but should be considered part of the algorithm if appropriate for your patient. I've showed you the evidence regarding the use of azithromycin and the ISHLT guidelines about instituting this in patients that are diagnosed with CLAD, specifically the BAS phenotype. It's very important that obviously you follow these patients very closely. You need to know what resources you have available. Look at the profile of your patients. What's their infectious profile? Do they have more of a RAS phenotype? Is a mixed phenotype? Are they infected? These are all important points to take into account. And if you continue to see disease progression or have a hint that disease is progressing with the drop in FEV1, this is time to consider whether or not you wanna use salvage therapy based on your center and its protocol or do you wanna consider initiating ECP? And if you're in Europe, maybe considering TLI. Other things that you need to consider in the care of these patients and treating these patients that have chronic rejection is reducing their infection risk, reducing their reduction of reflux and managing their reflux, enrolling these patients, if you can, in pulmonary rehabilitation, giving them oxygen and monitoring them for oxygen or need for supplemental oxygen when it is time appropriate. It's important and at the Cleveland Clinic, we refer all of our patients that are diagnosed with CLAD to palliative therapy for symptom control. We also get nutrition involved and our mental health team not only to support the patient or the recipient but also their caregivers. So the key takeaway points that I have is that there is no consensus on the most effective treatment for all these CLAD phenotypes. Currently, you wanna balance the risk and benefit ratio of using ATG, ECP or TLI if that's available to you but it's clear that single center studies that I've shared with you, they're great to generate a hypothesis but we truly need large multi-center randomized control trials to assess the efficacy of our current treatments and to develop future treatments. I wanna thank you for your attention. I wanna thank my team at the Cleveland Clinic for covering for me so I can be here in Hawaii and actually present to you and I'm happy to take any questions that you may have. Thank you again for your attention. Thank you.

lung transplantation

chronic lung allograft dysfunction

CLAD

perioperative aspects

early detection

treatment options

immunomodulating therapies

mTOR inhibitors

liposomal cyclosporine A

clinical trials