Thanks, Greg, for the introduction. And as Greg said, I'm gonna talk about heart and lung transplant in the same setting of using hep C infected donors to uninfected recipients. So here are my disclosures. And so what I'm gonna do is cover similar topics to what we've heard from the first two speakers, but focus on heart and lung transplant, both about the concept of transmit and treat, and then the possibility of prophylaxis to potentially prevent infection. And we'll talk about some challenges and opportunities that exist in this area. So when we look in the interferon era, prior to the advent of DAAs, and we see these are data from lung transplantation, and you can see that using HCV positive donors led to both crude and propensity score matched worse outcomes in terms of both recipient and graft survival. And the concept was that infection was universal in recipients and outcomes were worse with higher graft loss and mortality. And so the consequence of this was because treatment was really difficult, if not impossible, in the interferon era, both because of tolerability and because of the probability of increasing the risk of rejection, it was really unacceptable to both providers and patients, and it pretty much just wasn't done anymore. So it fell off the radar. But it's important to consider the fact that in many scenarios, these are otherwise young and healthy donors, and so the organs are often very good, and this was potentially a loss. And of course, the hep C world has changed dramatically, and that has really opened the door to considering this not only in kidney transplant, where one could make the argument that this speeds up the time to transplantation, but at least in the immediate short term is not life saving, whereas when you think about heart and lung transplant and liver transplant, often there's a much higher mortality, at least acute and short term mortality on the wait list. And that's what led to this first publication of experience of doing hep C infected donors in uninfected recipients for heart transplant. And this early report came from Vanderbilt with 13 recipients, and these were 13 donors that were hep C antibody positive, nine of them were NAT positive, and they had a strategy of waiting for viremia and then treating, because this was early on, it wasn't clear exactly what would happen. The nine NAT positive donors did lead to viremic infection, and then they treated the genotype one infected recipients with sophlitiposphere, and the genotype three infected recipients with sofosburopatosphere. Now importantly, what you see here is that they also waited here, they were waiting to see if viremia occurred, and they waited between 24 and 47 days post transplant. And what I wanna highlight here is that the median HCV RNA here is quite high, 6.4 logs, but up to 7.4 logs in the recipients prior to the time to treatment, and as a consequence, the time to negativity once they started antiviral therapy is relatively long for a new infection at 31 median days. Now you see that eight of the nine achieved SVR, one of the patients died of an unrelated pulmonary embolism at week seven and a half. So this was successful, but I would point out these very high viral loads, which have already been discussed and I'll come back to. And then this larger study that was done by the Harvard group and led by Ann Woolley, where they did both lung and heart transplants, predominantly lung, you can see 36 lung and eight heart transplants from HCV NAT positive donors. And in this, similar to what was done in the Penn study, they gave the soft val, in this case, not prior to the transplant, but immediately post-op. So this was done about three hours after the transplant, the person came back from the OR. So slightly different, but very close to the same idea of giving early treatment. And they treated for a total of four weeks. So what you see is that, first of all, viremia wasn't universal in this setting. So 42 of the 44 patients became viremic. But what you see is that the median viral load really varied. So it was much, much lower than what I showed you with those heart transplants from Vanderbilt with a median viral load of 3.26 log. And you can see a range from zero to 4.6. So really much lower. And it correlated with the donor viral load, which is perhaps not surprising. And they rapidly cleared virus. All patients were negative within two weeks. You can see the viral load curves here. So you can see they're rapidly negative. And you can see that it does correlate quite closely with the donor viral load. And you see that there was a range of genotypes, and as might be expected, that the majority were genotype one and genotype three. And importantly, they had excellent both short and at least medium-term outcomes. So you can see that all of the patients achieved SVR, and all of them, there was 100% six-month graft in patient survival. So very good short outcomes. They had shorter hospital stay when they compared them to recipients of HCV-negative grafts. And this issue of rejection also arose in this trial, where you can see that they did have an adjusted, increased risk of acute cellular rejection in recipients of grafts from hep C-infected donors. But importantly, their median waiting time has been noted previously, which is particularly relevant for lung and heart transplant, where so many people are dying waiting for organs. You can see that it was quite short at 22 days from the time of signing consent for lung, and 78 days for heart, which was, compared to their hep C-negative donors, was much, much shorter. So the question that we asked when we thought about this from the lung transplant side is clearly there are some problems with transmission. So is there actually a way to prevent infection in the recipients? And so the first approach that we thought about doing with this, at our center, our lung transplant program is very large, and they have really pioneered a lot of the work on ex vivo lung perfusion. And we're curious to see whether, if the organ is perfused outside the body in this circuit, would that reduce viremia to the point that you might not transmit virus to the recipient? So our initial study design was to look at this, taking HCV NAT-positive lung donors. They were, all the lungs were put on ex vivo lung perfusion for six hours with the concept that this would reduce viremia, went into hep C uninfected recipients, and then we measured the viral load daily. And initially, because we weren't really sure how this was going to work, we did wait to initiate treatment for a minimum of two weeks, and then we started them on therapy with cefosporavilpatysphere. And so what we see in the first 11 patients is that they did all become infected. So EVLP is clearly inadequate to prevent transmission. The viral loads were much lower at the end of EVLP by as much as three logs, but it did not prevent infection. And they all initiated treatment, but I think what's really important to note about this initial experience is out of these 11 patients, two of them relapsed after a full course of 12 weeks of soft val. And I just want to highlight these relapses. Some of the points have already been made, but I want to reiterate these points. So first of all, by a couple of weeks after transplantation, the viral loads were super high in these patients who relapsed. So above seven logs, you can see in both of them, almost eight logs in this recipient. And you can see that they relapsed post-treatment, and when they did relapse, the relapse was quite dramatic, with the viral load going, in this case, up above eight logs. We had to dilute it down to actually be able to get an actual quantity. In this case, the person had an asymptomatic relapse with no associated hepatitis, but you can see a very complicated resistance profile with multiple resistance-associated substitutions in NS5A and NS3, none in NS5B. Now, fortunately, this patient was retreated with soft valvox with ribavirin for 24 weeks, with no great rationale for that, except that we felt we had to give long-duration aggressive therapy, and fortunately, it worked. So this person did achieve SVR. And it's important to point out that this individual was on ECMO at the time of transplant, and was almost certain to die had he not received this organ. So although we were concerned, very concerned about this outcome, we did recognize that we had probably at least done him a short-term benefit by the transplant. In the other individual, again, a very high viral load at the time of relapse, but in contrast here, there was a marked hepatitis. You can see the ALT went up to 1,200. We biopsied this patient because we actually weren't certain if this was all related to hepatitis C, and we saw early fibrose and cholestatic hepatitis. So this really concerned us. We started the patient immediately on the same treatment regimen, and fortunately, he too achieved SVR. So we were able to salvage both of these individuals, but I think it highlights the point that relapse can occur, in this case, even with a full course of therapy, and really makes the case for getting treatment started early. So we then thought about the possibility of adding to our prevention strategy, and so we thought about doing something during EVLP. And we looked in the lab, and we could show that using light-based therapy, we could reduce the infectivity of HCV. And so what you see here, pointer to work, here we, you can see that there's a reduction in the viral load with ultraviolet light exposure to the virus, but more importantly, with after an hour of exposure of UV light, you can see that there's a complete loss of infectivity. So a greater effect on the viral infectability than on the HCV RNA level, which is important because that's something that is difficult to measure in vivo, and we may underestimate the effect of UVC. So what we did then is applied UV light during the ex vivo lung perfusion to see if that would reduce the infectiousness of the virus, and perhaps prevent transmission. And what we saw is that this did have an effect, but it was a modest effect. So you can see that the viral loads were lower, and the time to doubling of the HCV RNA in the patients that received organs after ex vivo lung perfusion with UV exposure were slower. And we did prevent transmission in two patients that had from that positive donors, but clearly this was not enough on its own. So overall, the early outcomes were good. We had good graft and patient survival, and they were all cured of HCV, including these two relapses. We didn't see any association with rejection in this initial study in the lung transplant arena. So, but our takeaways from this were that it was generally safe and effective that ex vivo lung perfusion reduced the viral load, but it wasn't adequate to prevent infection. And although UV light delayed time to viremia and slowed viral expansion, it was not adequate alone. We also had some challenges in this population using SofVal, particularly drug interaction. Some of these patients had postoperidmias, and amiodarone is contraindicated with sofosbuvir. We did use it in a few patients. They were very carefully monitored, and fortunately we had no consequences, but it certainly rose my heart rate while we were doing this. We also ran into some patients with renal issues and challenges of, again, using sofosbuvir. And the relapses occurred with these complicated resistance profiles, including the possibility of fibrose and cholestatic hepatitis, and really, I think, pushed the point that delaying treatment's probably not a good idea because these very high viral loads, by the time of treatment, may be a reason for the relapses. And you've heard about this idea of prophylactic treatment, and we thought that this would be effective, as have others. So the other thing is that the use of lecaprevir proprentosphere might have some advantages here. It's also pangenotypic, it's safe in renal failure, and it has some drug interactions, but at least for the transplant population, other than cyclosporine, fewer relevant drug interactions. So this study done by the Harvard group looked at 20 heart transplant recipients from, again, NAT-positive donors, and here they gave the first dose of lecaprevir proprentosphere pre-op, and then for eight weeks, so a full course after. And notably, they did have five patients that were antibody-positive and NAT-negative, and here they waited to see if they were viremia with the intention to treat, and none of them became viremic. So what you see is that when they used this approach, only 12 of the 20 patients ever had detectable viremia, and all of them achieved SVR with eight weeks of treatment. And you see that their peak recipient HCvRNA was very low at 311 IU per ml, and their time to HCvRNA negativity was very rapid at under four days. So this was well-tolerated, highly effective, and all the patients were cured, and most of them never became, or at least a minority of them never became viremic. You can also see that it markedly shortened the wait list time. So we wondered about then combining strategies, and so we were interested in seeing whether we could block entry of the virus, and the HCV viral entry is a complicated process involving at least five entry factors, and I just wanna highlight this one that was demonstrated by Susan Uprichard's group, the Niemann-Pick C1-like cholesterol absorption receptor, which they showed in this nice study a number of years ago. If you silenced this receptor, you could block HCV infection in cells, and this also happens to be the ligand of ezetimibe, an approved, safe cholesterol medication which could reduce in cell culture the entry of HCV into cells, and more importantly, in a humanized mouse model, also limited HCV infection. And so with this, we had the idea to try to combine antiviral therapy with an entry inhibitor. So again, in this case, we decided to expand it to all organ recipients. For the lung recipients, we continued to give them EVLP if it was clinically indicated, and then the UV treatment as, because it seemed to have at least some effect. For the other recipients, they did not receive EVLP, so either the lungs that didn't need it clinically, or for kidney, heart, or kidney pancreas transplantation. They got one dose of pretreatment ezetimibe and glucapravir probrenosphere, and then afterwards were treated for seven days post-operatively to follow their course. We measured the HCVR on the daily for the first two weeks and then weekly out to 12 weeks. And so here are the donors and recipients, and you can see that 16 donors, because we were able to use multiple organs from the same donors, it went into 25 recipients. And just to highlight a few points about them, that the age was quite young. The donors were 36. They did have fairly high viral loads, up to seven logs, and a variety of genotypes, but the most common ones being genotypes one and three again. And you can see that this, so far we've done 25 recipients with 12 lungs, eight heart, four kidney, and one kidney pancreas. And so this sort of summarizes the results to date that we saw these high viral loads in the donors before transplantation, and you can see that in the recipients, the majority of them either had no or unquantifiable viremia after transplantation, and they rapidly became negative. And to date, we have 18 have reached 12 weeks of follow-up with no relapses, seven have reached six weeks of follow-up with no relapses. So we've been comforted by the fact that we've had no virological failures to date. And we can see that the same thing that was reported previously, that the major predictor of transient viremia in the recipient is the height of the donor viral load. So you see that seven of the patients had never had detectable viremia, and had much lower median viral load than either patients who had detectable but unquantifiable viremia, and those that had quantifiable viremia. And aside from that, the only other factor that was associated with transient viremia in the recipient was genotype three infection, which has been slightly harder to treat with direct acting antivirals to date. And interestingly, and it's hard to interpret it with the small numbers, but ex vivo lung perfusion was used in six of the 12 lung recipients, and you can see none of the six that had EVLP with ultraviolet light exposure had quantifiable viremia, whereas half of those that did not get EVLP did have quantifiable viremia. So the question that we continue to ask is whether this residual RNA is from the donor, or whether this is truly infection and replication in the liver. And it's one of the questions that I would even ask about that JCI study that Christine nicely showed is whether they were actually sequencing residual donor virus. And I know they tried to exclude that possibility, but it's a difficult thing to exclude, and at least it is one possible explanation for why there was such strong similarity between the donor virus and the early virus in the recipient. So in summary, short course therapy with one dose pre and seven days post transplant prevented infection in 25 recipients with high donor viral loads, varying genotypes, and a variety of organ types. And all heart and lung recipients completed their therapy prior to hospital discharge with no significant safety concerns. So another one of these pro and con slides, we all put them together, and I think they're similar. I think we highlight some similar themes here that there's the idea of prevention with either the strategy that we've used or some other strategy is really, I think some benefits are potentially finishing before hospital discharge, which is of course most relevant in the lung and heart transplantation and less so in kidney. This seemed to be well tolerated both orally and by NG2 when delivered in the ICU, but I think it's fair to say that we don't have a lot of data on the PK and reliability of delivery of these drugs using NG delivery. There was high patient acceptability. Obviously this reduces cost, and at least for us, because we didn't have to worry about the insurance, which is a benefit perhaps of being in Canada, but it's also a benefit that this can be rolled into the transplantation package if you consider this and it's part of the institutional cost for the transplant. So I think there is another way of getting them covered if you do it in this scenario. I would also argue that relapse is likely not to be resistant when you use high barrier drugs with short course therapy. That's been reported previously, although I think it's definitely notable that this very short course therapy that was tried by Rich Sterling and colleagues did lead to resistance even with very short exposures. Challenging of this approach is coordination of the pre-transplant dosing can be a bit tricky. Certainly these are very sick patients with multiple medical issues and that needs to be considered. We did see some mild liver toxicity, at least manifested as reversible transaminase elevations with Glucaprovera probrenosphere, and I think at least from our data, because it's uncontrolled, we can't really say too much about the role of ezetimibe. We had some hint that it's probably useful, but I certainly can't be certain about that. Contrasting this to treatment after transplantation with SoftVel, certainly it's well tolerated and these patients are more medically stable, and most of the data show very high cure rates, which is reassuring, but I think it's important to remember some of the drug issues, particularly the amiodarone concern in heart and lung, well, mostly lung transplant recipients. Cost and coverage become an issue for the outpatient. We've heard about that already, and this at least rare risk of relapse. So finally, to summarize, heart and lung transplant from hep C infected donors is generally safe and feasible. I think a short course therapy for prevention may have some significant advantages over post-transplant treatment, but both strategies work very well, and I do think it's important that we really don't lose sight of the fact that this really is a consequence of the opioid epidemic and the overdose crisis, and although we should absolutely be making some small good come out of these tragedies, we should still be working very hard to try to prevent these overdoses in the first place. Thank you very much. Thank you.

transplant

Hepatitis C

prophylaxis

antiviral therapy

opioid epidemics