Tenax Therapeutics, Inc. Aktie

Good afternoon, and welcome to the Tenax Therapeutics Virtual KOL Call. [Operator Instructions] Please note, today's call is being recorded. I'd now like to turn the call over to Chris Giordano, President and CEO of Tenax Therapeutics. Please go ahead.

Thank you, Betsy, and welcome, everyone, to an in-depth discussion of the science behind Tenax's ongoing development program in PH-HFpEF. We're developing TNX-103, an oral formulation of levosimendan, which we believe has the potential to be a first-in-class treatment for PH-HFpEF. TNX-103 is currently in late-stage development in the Phase III level study with top line data expected in the second half of 2026 and also LEVEL-2, a global Phase III study on track to initiate this year.

Tenax is not alone in focusing on patients with the most common form of PH for which no drug is approved. And it's great to see more and more investigational strategies being evaluated in these patients, considering the grave unmet need that patients with PH-HFpEF face. At Tenax, we get a lot of questions about the differences between our PH-HFpEF program and work done in the space by other researchers. For example, we focus on a different physiologic target than other drugs in development. We have a unique mechanism of action and aspects of our trial design designs are really different to other PH-HFpEF trials, et cetera.

So we thought we'd spend an hour today. We thought it'd be good to dig into these differences and explain that these differences are intentional. Demonstrate they're grounded in established science and a deep understanding of the disease and of this patient and hopefully build your understanding of why these differences could be important. Also, we thought it would be good to provide you a viewpoint on these differences from experts outside the company.

So before I introduce our speakers today, I'd like to remind everyone that we'll be making forward-looking statements during the event, and please review our disclaimer shown on the slides. Today's discussion will be led by Dr. Stuart Rich, Chief Medical Officer of Tenax. Stuart is joined by Dr. Barry Borlaug, Professor of Medicine and Cardiology at Mayo Clinic; and Dr. Sanjiv Shah, Director of the HFpEF program at Northwestern University's Feinberg School of Medicine. So Stuart will present viewpoints on these key issues that we face when addressing the PH-HFpEF and then moderate discussions among these experts before we open the lines at the end of the call for live Q&A.

So I'll now hand over to you, Stuart, to begin the panel discussion. And thanks again, everyone, for joining us.

Thank you, Chris. So I'm going to start with the topic of volume overload. The question that we often get is, isn't it accepted that excessive blood volume in the heart and lungs of patients is a cause of PH-HFpEF. So the title of this slide is the title of a paper that was published by Milton Packer, one of the most renowned KOLs in heart failure history. And it's entitled Impaired Systemic Venous Capacitance, the neglected mechanism in patients with heart failure and a preserved ejection fraction. This was published in 2020 right after we had published the results of our Phase II HELP study and the assessment of the mechanism of action of levosimendan.

And as Dr. Packer points out, it's not something new. It's something that's been neglected. And in the paper, when he discussed the dominant phenotypes of patients with this disease, the hypertensive phenotype and the obese phenotype, he acknowledges that venous blood volume is increased in both of the phenotypes. If you're not familiar with what we mean when we talk about excessive blood volume in the venous circulation, take a look at this lady's neck vein. It's markedly distended and it's filled with blood. It's almost like a monometer telling you that the pressure in that vein is quite high. The blood volume is so high that it's not only distending her vein, it's overloading the right side of her heart, her lungs and the left side of her heart at the same time. This is a fundamental problem in HFpEF and in PH-HFpEF.

So to try to explain to you the physiology, if you look on the left side of this slide of a healthy person, you will see at the top, there are lungs, then there is the heart and then there's a splanchnic reservoir. Splanchnic refers to the abdominal organs, which consist of the liver, the spleen, and the small and large intestine. It has a very large blood supply and actually holds about 30% of all of the blood in your body. It's a reservoir because it's there for when you need it, just like gas in the gas tank of your car.

And so when you are sleeping at night, your physiology kind of looks like this. The reservoir is filled. The lungs, not so much because you don't need a lot of blood in your lungs to take up oxygen while you're sleeping. If you're one of these people who jogs in the morning, when you get up, you need the extra blood volume so that you can run, you get a signal from your sympathetic nervous system to constrict the blood vessels in the splanchnic reservoir, kind of like squeezing a sponge and getting more water out, that blood will go into your heart and then into your lungs and then into your body with more oxygen.

The arrow drawn next to it going in two directions tells you that all day long, this is going on in you. But depending on what you're doing, there are times when you're resting and the blood volume is in your abdomen and times when you're running and the blood volume shifts into your heart and lungs. On the right side, however, is an illustration of what happens in patients with PH-HFpEF. And here, if you look at the lungs, the lungs are totally full and totally full all the time.

Splanchnic reservoir, however, is constricted and not entirely filled. And this is why you see that lady's neck vein being so distended because so much blood is coming out of the reservoir into her neck, into her heart and her lungs. And we've drawn this large arrow to show you that it's kind of one way, which means that this is continuous happening all the time during the day. And thus, our goal is to try to change this abnormal physiology of PH-HFpEF and restore it back towards a healthy physiology. So let me stop here and ask our experts what their thoughts are about this mechanism. Sanjiv, why don't you start?

Thank you, Stuart. Yes, I think that this is something that's been around in our sort of history of physiology since the 1960s and '70s is sort of this excessive splanchnic blood volume. And it's something that I think was forgotten for a long time until it was resurrected about 10, 15 years ago and people started getting interested in again because we started noticing with implantable pulmonary artery monitoring like CardioMEMS and others like it that you'd see a phenomenon that was different than what we thought typical.

So I think in doctors' minds, we think, okay, heart failure patient, they have a high -- maybe they're eating a lot of salty food. They're eating too much fluid. They're not taking their medications and all of a sudden, over weeks and days, they slowly have a buildup of volume and then they get hospitalized for heart failure. But once we had these implantable hemodynamic monitors, what we saw was that it actually happened a lot more abruptly than that in many cases. So it wasn't this gradual increase in body weight or something like that or pressures. It was an acute rise in pressure, let's say, in the pulmonary artery in the case of CardioMEMS. And it was that acute volume load that led someone to a hospitalization.

So it was the shift of blood volume from the splanchnic to the chest and to the heart and lungs that were stiff that seem to be causing it. And so there's sort of two things. I would agree with you that this can cause, I would say, an exacerbation or worsening. I mean the primary thing that's going on is you have a congested or you have a remodeled heart. You have a stiff heart muscle, you have maybe elevated sort of remodeling and elevated resistance in your pulmonary artery. So there's disease there. That -- but the disease people can live with. It's the fact that then the body has this excessive splanchnic vasoconstriction, excessive blood volume that's going to the chest that it can't handle. And that's what causes the symptoms. That's what causes the heart failure hospitalizations. That's what causes the exercise intolerance. And so by reducing the load on the heart and the lungs, patients can feel a whole lot better.

Barry, do you want to add to that?

Yes. I mean, obviously, this system exists, it's evolutionarily selected for. This has a teleological use. So in the example here, on the left, that's at rest. We have this going to the right that instead of being PH-HFpEF, the bottom part at least could be like a normal human like in the setting of stress. So when you jump up and try to run away from a tiger that's chasing you, your autonomic nervous system is activated and you get venoconstriction in all the veins in the splanchnic reservoir. So it goes from being on the left to the right. I mean that's what we need in order to enhance blood return to the heart so that the heart can then rapidly pump that blood out to the body. So this is a good thing.

But the problem in chronic heart failure is chronic heart failure, including PH-HFpEF, is associated with pathologic chronic elevation of that autonomic activation. So those veins are just constantly constricted. That's because our bodies aren't -- we didn't evolve to live through heart failure. These mechanisms are there to help us in fight or flight stress systems. But when you activate these pathways chronically, you get this excessive venoconstriction and then you're squeezing all this blood into a heart that, as Sanjiv points out, is stiff, cannot accommodate that increase in blood. So you're just making it much worse. So essentially, the body's so-called adaptation or what I think it's doing as an adaptation is making the disease much worse. And we think that, that's an important therapeutic target.

Thank you, Barry. So going on to the next question regarding proof of concept. Is there data that shows reducing the blood volume in the heart and lungs of patients with PHFpEF will result in hemodynamic improvement. So I'm going to show you some proof-of-concept slides of things that were done. The first one was a mechanical approach to pre-load reducing devices. Pre-load and volume load should be considered the same thing. And what they did is they took catheters with balloons on the end. The one on the left is an SVC balloon that stands for superior vena cava and partially occludes the major vein coming into the heart from the upper body. The experiment on the right used the IBC, inferior vena cava and inflated a balloon into the major vein going in the heart, receiving blood from the lower part of the body.

But what they showed with the SVC balloon experiment, which was to inflate the balloon and let the patient lie there for hours to see what would happen is a dramatic reduction in the pulmonary wedge pressure shown in blue and the right atrial pressure shown in red over time. On the right side, they wanted to look at the effect on rest and exercise. And so they kept the balloon up while the patients were exercising and then noted also that during exercise, there was a fall in that right atrial pressure, pulmonary pressure, but no change in the cardiac output that is necessary to be able to perform the exercise.

Building on to that, the Duke University Faculty said that if, in fact, this is the sympathetic nervous system triggering this, can we block the ganglion that controls splanchnic circulation and maybe treat it that way. And so the illustration on the left shows that they take a spinal needle and put it into patients and inject lidocaine, which will paralyze that nerve for about 6 hours. And the hemodynamic results are shown on the right. This is data from rest and exercise right heart cath. So if you look at the right atrial pressure screen, you're seeing baseline data in blue, nerve block data in red, and the conditions that they are measured is lying down with their legs flat, their legs up, exercising and then stopping exercise.

So what you see is the right atrial pressure, which is normally about 5, markedly elevated before coming down dramatically at rest and exercise. Similarly, if you move to the wedge pressure, normal should be about 10, you're seeing a dramatic elevation in wedge pressure before coming down substantially with the nerve block. But important to point out, the ability for the heart to pump normal amount of blood, the cardiac index was not negatively impacted. So this is the science behind our development of levosimendan, a drug that has site-specific venodilatation properties on the splanchnic circulation.

And so in our Phase II HELP study, we had two parts, the first of which was based on mechanism of action. Patients came in for a rest and exercise heart cath, we hospitalized so they could receive an intravenous infusion of levosimendan for 24 hours and then came back to the lab the following day so that we could see what kind of changes existed in the filling pressures of the central venous pressure and pulmonary wedge pressure. Same format, you see the baseline pressures in blue and the treatment pressures in red, legs down, legs up and biking. And you can see dramatic falls in all three conditions in these patients.

Interestingly, all of the patients that were in this study, we targeted the peak increase in wedge pressure as the primary endpoint and 85% of the patients enrolled in that trial responded to a reduction in the exercise wedge pressure, the first time that has ever been demonstrated. Then we took the data from this with the volumetric data obtained with simultaneous echocardiography and Dan Burkhoff in his laboratory was able to compute the blood volume changes. And what you're seeing, levosimendan on the left and splanchnic nerve block data on the right, that it was a reduction in that blood volume that was accountable for the hemodynamic changes we saw. Barry, what do you think about this data?

Yes. I mean I think that this is a good model, which explains what we saw in the trial. And we didn't see a lot of other effects in terms of contractility and that could -- or diastolic function that could account for the observed hemodynamic benefit. So this really does point to more of a venodilator effect, which we think is key for all the reasons that we articulated in the earlier slides.

Sanjiv, your thoughts?

Yes. Well, we've learned a lot from studies in HFpEF. And I want to contrast what we saw in the reduced LAP-HF2 atrial shunt trial, and that's where we're actually increasing load to the right side. And then the sort of the Axon rebalance trial where we're doing the splanchnic nerve block and level and what we see there. And so what's interesting is that if you just block the splanchnic nerve or you give a pure venodilator like nitrates. And of course, nitrates have a lot of other properties that may not be good in HFpEF.

But let's just say the splanchnic nerve block when you do that, you're reducing pre-load, you're reducing the very thing we're talking about. But it didn't -- in the trial, we did rebalance, it actually seemed to not work very well in patients with pulmonary hypertension. And the reason I think is because the -- you're just dropping the nerve and you're not doing anything else. We know that levosimendan has other properties. And I think it was supporting the right ventricle.

Normally, if you reduce blood volume with exercise, your cardiac output can go down. Now the right atrial pressure in our patients in the HELP trial was very high. And so you often don't see that. But we can't argue with the nerve block results. On the other hand, with the shunt, when you increase blood to the right side, the ejection fraction goes up. And so I think that my personal opinion is levosimendan doing two things. It's sort of relaxing the blood vessels in the splanchnic, but also supporting the right ventricle, so it doesn't respond poorly to that, especially during exercise.

So I would have expected that we might have seen a slight reduction in cardiac output with what -- if it was just venodilating the splanchnic vasculature, but the fact that the cardiac output maintained and was constant, I think, is a sign that this is really the best of both worlds. And I think that's why it works so well in this patient population.

I think another point that's specific to patients with pulmonary hypertension, and this is a little bit more complicated and not really shown in these slides. But they have the right heart and the left side of the heart compete for space. And in these patients, a lot of times, the right heart is very dilated and it squishes down on the left heart. So the pressure in the left ventricle, which is what causes fluid to build up in the lungs is high, but the left heart itself is small and underfilled. So a little bit of reduction in blood coming back to the right heart can paradoxically improve the left heart filling, and that can offset any potential reductions that you might see from this.

I think the other key difference between this strategy and the splanchnic nerve block is that -- I mean, you're killing the nerve. It's only one nerve, but it's gone. Whereas this is just kind of taking the top off. Splanchnic nerves can still fire with like a drug that causes venodilation. So it might be a little bit better tolerated, too. That's another alternative explanation. This is all -- what we're saying here is speculative. We don't know at this point, but this is what we believe.

Great. Thank you for that comment. All right. Now we are often asked how has the Phase III level study been derisked to assure a positive outcome. So there's three points I'd like to make. The first one is that the Phase II HELP study that we did confirmed that levosimendan produces a reduction in wedge pressure with exercise in these patients. The illustration for those unfamiliar shows a patient lying on a cath table with a mounted bike. And when we talk about rest and exercise right heart cath, that's kind of what it looks like.

The hemodynamics on the right side of this slide actually come from Dr. Borlaug in a paper that he published. And what he elegantly demonstrated is that patients without HFpEF and normal wedge pressures at rest have very little increase in the wedge pressure when they exercise. But those patients with HFpEF shown in red, have a dramatic increase in their wedge pressure with exercise because they are unable to handle that increased volume loading at the time. If we are doing a clinical trial where our primary endpoint is going to be a measurement of exercise capacity, we felt it was essential to know what the hemodynamic changes would be when our patients exercise. To my knowledge, no other study in PH-HFpEF has ever provided supporting exercise hemodynamic data the way we have.

Secondly, we've enriched our Phase III trial based on the hemodynamic profile of the patients in the Phase II HELP study that responded to the drug. And so we're kind of assuring ourselves that the patients we're enrolling are ones that have the best opportunity to have a favorable response to the drug. The hemodynamics are shown on this slide. At rest, they must have a wedge pressure of 18 or higher, a mean pulmonary artery pressure of 30 or higher that goes to 20 and 32 with leg raise and 25 and 35 with exercise. These are very high pressures. It's a sick population with intention.

Finally, I want to point out that all of the level data that preceded the trial came from the use of intravenous levosimendan. The patients in the HELP study got an infusion of levosimendan once a week, knowing that the drug would wear off as the week went on. The active drug is this metabolite 1896. And when we did our 6-minute walk assessment after 6 weeks, it was done towards the end of the week when the level of 1896 was low, and we received a 29-meter treatment effect, which was considered remarkable, in fact, the only positive study in this group of patients.

We then are going to an oral formulation, as you probably know, in our Phase III program. We have legacy studies with oral levosimendan administered chronically for over 6 months in patients with heart failure and 12 months in patients with ALS, and that has provided us with a great amount of data on the optimal daily dosing, the efficacy and safety of the trial. So one would assume that if the patients now are taking daily drug, with a therapeutic level of drug, they would respond better to the oral rather than the IV.

We did a transition study of the patients who were in the open-label extension of the HELP trial on IV therapy for up to 2 years, who all wanted to take oral levosimendan in its place. And as we had anticipated, they would feel better, walk farther and have better cardiac output and the results of that transition study showed 6 of 7 positive improvement in symptom domains of the KCCQ and additional improvement in the 6-minute walk of another 7 meters and a measure of the natriuretic peptide down 23% over the level from the IV therapy. Sanjiv, what do you think of this?

I think the graph show it all. I mean I think that it really seemed to dramatically reduce and improve hemodynamics. It also improved exercise capacity and did what we thought it was going to do. I think if you're not doing the studies and you're not in the room when this is happening in these multicenter studies, exercise invasive hemodynamics is really kind of messy. I mean it's like the patient is moving around, the catheter is whipping all over the place, and it's really hard to show a benefit.

And so the fact that we saw these reductions in the hemodynamics, especially when we were thinking about when was this repeat right heart cath done, it was like a trough level of when the levosimendan IV was getting infused. And then on top of that, we see that the patients transitioning to oral did even better, I think, is really quite fascinating. I mean I didn't -- I have to say like I was worried that you go from IV to oral and what we saw in the patients was really remarkable.

And so I do think that it's active, and we're hitting what we typically don't. I mean, it's very difficult to improve 6-minute walk distance on -- in HFpEF. I mean GLP-1 receptor agonists have done it. We had one trial with an SGLT-2 inhibitor that did it. It was called PRESERVED, the rest of it didn't. But these are like 20-meter increases. I mean we had more than that here in a sicker population, which I thought was remarkable.

And sometimes you'll see like a fluke, these are small studies, even though it was randomized, you might see a fluke, maybe there was an outlier here or there. But I mean, we had -- it wasn't just that there was like a random 6-minute walk distance improvement. There was real hemodynamic improvement, and it was more pronounced in the stress blood volume and it was more pronounced at low levels of exercise, which is what -- where patients live. So I think it's a small randomized trial, but it really set the scene for where we are now with LEVEL-1 and LEVEL-2.

Barry, you're one of the highest enrollers in HELP and one of the highest enrollers in LEVEL. So what's your sense from the patients that you've enrolled in these trials?

Well, I think patients love it. I don't think. I know they do. I think it's really telling that for the IV formulation, I mean, patients had to get -- they had to have a PICC line, like a permanent IV line placed, which is associated with infection and clots and things like that, and they had to get an infusion once a week, real pain in the butt. And as Sanjiv points out, the levels would decade just until as the days elapse and you get closer to your next dose, it would kind of wear off. And despite all that, they were just dying to remain on the medicine because it was really helping them to feel substantially better.

So the fact that we now can do this with a pill is incredible. And as this Slide 15 shows that even above and beyond the IV, the pill was not only maintaining the benefits that we saw in the acute trial, but actually improving upon that. And in the LEVEL study, there is an open-label extension. So even the patients that received placebo initially have an opportunity to get the real drug, and it's really been life altering for many people. And I've participated like Dr. Shah, we've both been involved in a lot of different clinical trials over the last 20 years in HFpEF. But I would say that the effects that we're seeing here that the patients are telling us are really, really impressive.

So now I want to discuss pulmonary vascular resistance or PVR. We are asked, is the change in PVR an appropriate hemodynamic endpoint to measure drug efficacy in PH-HFpEF because we do not use PVR as a meaningful hemodynamic measure of efficacy. So for those unfamiliar, the pulmonary vascular resistance cannot be measured directly in people. And so as a surrogate, this equation was developed back in the 1950s, which is derived from the mean pulmonary artery pressure minus the mean pulmonary capillary wedge pressure divided by the cardiac output. And so the PVR is considered lower is better.

And so you can lower the number overall if the cardiac output goes up, and/or if the pressures come down. So this slide kind of is meant to show you why the PVR can go in the opposite direction that you would consider it to be a useful representative. It has been used in the Group 1 PAH trials, and it seems to be helpful. However, I want to remind everyone that the wedge pressure is normal in those patients and doesn't change. So if you look at the example on the right, I've chosen numbers that are kind of really realistic numbers that we see in patients, a baseline PA pressure of 40, a wedge pressure of 25, and a cardiac output of 5, that computes to 3 wood units.

If you want to make your endpoint lowering PVR after treatment with a typical pulmonary arterial vasodilator for Group 1, what you will see is a drop in the mean PA pressure and an increase in the cardiac output. The wedge pressure may stay the same or may even be higher. And in this example, you see a typical hemodynamic effect with the wedge pressure from 3:1 going down 60%, and this is an adverse response in this disease.

Look to the example on the left. This is an example to represent what we've seen with levosimendan, same baseline hemodynamic numbers, 3 wood units. After treatments, we dropped the wedge pressure from 25 to 15 upper limit of normal, maintain the cardiac output and lower the PA pressure. Now the PVR computes to 4 wood units, you would say, hey, you increase your pulmonary resistance by 30%. Is that bad? And we would say no, it's actually a very good treatment response. Barry, what do you think about this?

Sorry, I had trouble getting off mute there. Yes, I think that this is -- for this very reason, this can be misleading here. A high wedge, we think a high -- the wedge pressure, of course, is a surrogate measure of the left atrial pressure, and that's the proximate cause that leads to the lung congestion, water accumulation in the lungs. And if that goes up, that's exactly the opposite that we want to achieve in patients with heart failure and preserved ejection fraction. So I think this example is illustrative in that way.

Sanjiv, do you have some thoughts?

Yes. I mean I think that it boggles my mind because we -- of course, I work on all these trials with all these companies. And two things just drive me crazy. One is this hyper focus on the pulmonary vascular resistance, and I've told them all that because the right ventricle compared -- I mean, what it cares about either at rest or exercise is, I think, the total load. Like what's the total load it's seeing when it's trying to contract? And what is that total after load? And it doesn't care if it's the PVR or it's -- what part is coming from the left atrium pulmonary veins. It's all the -- it's sort of the total load.

And so separating out the PVR makes sense, like you said, when you have a very low wedge pressure in pulmonary arterial hypertension, but doesn't make sense at all when you have pulmonary venous hypertension or a combined post and precapillary. So there's so much more that's important that we don't focus on. And I think in the patients, what we see is, obviously, what we really care about is do they improve their exercise. I mean, their ability to do things and their 6-minute walk distance, their excise capacity. And what that usually translates to is that they have -- they're decongesting and lowering the PVR doesn't necessarily mean that.

So I just -- I think that there are better ways. And the other thing is it really boggles my mind that we don't do exercise more. We're not like trying to see what -- I mean, these patients are really symptomatic with exertion. So if we don't do exercise or some sort of maneuver to see what happens when you're stressing the system, then you're going to totally miss out. I mean the splanchnic vasoconstriction, that typically happens when the patient is under stress and either they're exerting themselves or some other stressor. And so if they're just lying there, you're doing your study at total rest, you just won't see it. So those are the two innovations, I think we see here in the LEVEL trial that makes it different than every other pulmonary hypertension development going on.

Go ahead, Barry.

Yes. I mean I think just to expand on that, I mean, this is the concern with using isolated pulmonary vasodilators in patients with HFpEF because you're basically unlocking the screws to let more blood go through the lungs, and it's going to go to a left atrium that already can't accommodate that. So if you're not treating the high left atrial pressure at the same time, and Stuart is, I think, going to show some of the examples of pulmonary vasodilator trials in HFpEF. I think we really need something that's going to lower that left atrial pressure. And that's really shown nicely on this Slide 18, the difference between the good and the bad scenario.

Okay. So by the way, you're setting me up pretty well, Barry, for the next question here. We are going to just quickly give you our views about other clinical trials in PH-HFpEF, as Chris acknowledged from the start, there are other companies actively pursuing treatments, and we applaud that. The question that we're asked is about data showing that pulmonary vasodilators or relaxing analogs in PH-HFpEF will result in hemodynamic or clinical improvement.

So currently, there are three trials ongoing that are including patients with PH-HFpEF. That one is the CADENCE trial with sotatercept, which is an FDA-approved pulmonary arterial vasodilator. One is a relaxin analog being developed by Tectonic called the APEX trial, and one is a relaxin analog being developed by AstraZeneca called the Re-PHIRE trial. All three studies enroll patients based on a standard definition of PH-HFpEF without enrichment, meaning that all they need is a mean PA pressure above 20 and a wedge pressure above 15.

My concern here is just that this sets themselves up for misclassification of some of the patients because the definition of PAH would be a wedge pressure of 15 or less and Group-2 PH, a wedge pressure of 16. And the fidelity in many cath labs with the fluid field catheters may not be able to discriminate correctly those two separate groups. In addition, as we just reviewed, all three of these studies have designated a reduction in PVR at rest as the primary endpoint. All three drugs also have as a mechanism of action, a pulmonary arterial vasodilator. There have been now six randomized clinical trials in the approved pulmonary vasodilators for HFpEF and all of them have failed.

So I want to kind of go a little deeper into this as Barry kind of set me up as to what is going on as why they're getting a bad result. So this drawing, I did to show what has been called protective pulmonary arterial hypertension, something that was clarified way back at the time we had mitral stenosis as a cause of pulmonary hypertension. So I'm going to talk you through the drawing. You see RV stands for the right ventricle. P is the pulmonary artery. That pulmonary artery goes into the capillary next to the alveolus. We call that the alveolar capillary interface. And this is where oxygen, the O2 is -- this is where oxygen is exchanged from the lungs into the capillary bed. That blood flow then goes into the pulmonary venous side, which is the capital letter P and then the left ventricle.

And so patients with PH-HFpEF have an enlargement in their left atrium because of the very high pressures in the left atrium. Those pressures will move backwards and start to injure that very precious interface, we call the alveolar capillary interface. And the net result is oxygenation is difficult. That is a threatening biologic signal to the survival of the person. And so the body does its best to try to come up with an adaptive response to protect against that injury. And the adaptive response is number three, constriction of the pulmonary arterial bed. The constriction of that bed limits the blood going from the right ventricle and pulmonary artery into the pulmonary vein and does its best to prevent that elevation in the wedge pressure, especially with exercise, which goes ahead and injures that interface again.

If your drug treatment is targeting #3 to dilate the pulmonary arterials, as Barry alluded to, more blood will start going into the left atrium that wedge pressure gets higher and the injury gets worse. So these are the results of two trials that were presented this year that were unsuccessful in HFpEF. It just so happens our KOLs were the PIs in the trial. The macitentan trial is known as SERENADE and the volenrelaxin trial is known as HFpEF. What I've demonstrated are the outcomes curves that were published in those manuscripts, and I'm going to let the authors of these papers talk to you about them themselves. So Sanjiv, what can you tell us about the SERENADE trial?

Yes. Well, we thought we were clever, and I have to say I thought it was a valiant effort. We know that endothelin receptor antagonist do cause fluid retention. We also know endothelin is a major player in heart failure and pulmonary hypertension. So we wanted to try to design a smart trial that maybe would take advantage of this. And what we based that on was the fact that it seemed like in early trials of endothelin receptor antagonist and heart failure reduced CF, if patients did not have congestion at rest and they had more of -- they weren't fluid overload and they didn't have increased fluid in response to endothelin receptor antagonist that they could do better.

So we designed the trial with a run-in period for 4 weeks on placebo, then 5 weeks on macitentan, everyone got it. And if they developed fluid overload or were unstable, they were out. And then we randomized them. And as you can imagine, it was a very hard to enroll trial. And yet, as you can see, I mean, it wasn't statistically significant, but the signal is certainly there. Macitentan, despite all that, was still ineffective and in fact, worse. It still caused the fluid overload despite everything we did. So that really was the nail on the coffin for me. And when I'm thinking about it, and we'll see what Barry has to say about volenrelaxin and I'll let him talk about that one.

But what I think happens with a lot of these medications is that there's a neurohormonal response. So there's -- it could be a direct drug effect. It could be the fact that the body is responding to that hemodynamic signal with trying to retain fluid, probably a little bit of both of that. I think the problem with endothelin receptor antagonist is that they cause increased capillary leak, but also a lot of fluid retention at the level of the kidney. And we know that endothelin blockade itself basically goes to the cardiomyocyte natriuretic peptide, NPPB and NPPA promoter region and shuts off natriuretic peptide. So if you block the endothelin receptor, your body is going to think that it needs to lower natriuretic peptide gene expression. So that's not good. So there's many reasons. And I think that's why that doesn't work. And I think any drug that's a pulmonary vasodilator, you have to really kind of look at what other ill effects it might be having.

Barry, can you shed some light on the volenrelaxin trial for us?

Yes. So relaxin is a peptide hormone that's made by the placenta, and it's a vasodilator and it's responsible for a lot of the adaptations that happen in women when they're pregnant to support the fetal circulation. And there were trials years ago of IV relaxin in acute heart failure, and it showed a lot of evidence of positive benefits, including hemodynamic benefits with decreases in PVR and decreases in left atrial pressure and pulmonary artery pressure. But it's IV, so it can only be given for a couple of days. That led many different companies, including Eli Lilly, who made volenrelaxin, but others, as Stuart pointed out, with active compounds to try to engineer a longer-acting formulation of relaxin.

So that's what we tested in patients with HFpEF, and we're very hopeful based on the acute responses that had been previously shown with IV relaxin that we'd see a benefit. But unfortunately, as you can see here, we did not. This is just an exploratory safety analysis here, but this is showing a 2.6-fold non-significant increased risk in heart failure hospitalization in patients who were with HFpEF were treated with volenrelaxin as compared to placebo. And it wasn't just this. We saw the signal through multiple other metrics. We saw decreases in hematocrit indicating dilution of the blood from water overload and worsening congestion.

We saw an increase in NT-proBNP level, which is a biomarker that's reflective of fluid status. Patients were less likely to have an improvement in functional class, it was really a consistent bad message across the board. So again, it's the same point that Sanjiv was just making. A lot of times, some of these drugs that dilate can have other untoward effects that promote volume retention and you end up shooting yourself in the foot. So I think that's been a big concern for these and other studies that have looked at other drugs like PDE5 inhibitors have also shown evidence for either neutral or for harm that is a different kind of pulmonary vasodilator. So I think we need to be clever, and I think we are being clever with levosimendan through its distinct mechanism of action.

So I do want to thank both of you for shedding your brilliance over these topics. I'm going to now shift back to the operator for an open question-and-answer session. Thank you so much, guys.

[Operator Instructions] The first question today comes from Dave Risinger with Leerink Partners.

I apologize about the background noise. So thank you very much for the very detailed presentation and for sharing all of your perspectives and insights. I have two questions, please. So I'm going to go out to a little bit higher level. First, could you talk about the requirements for FDA filing and whether an accelerated filing might be possible after you collect additional safety data in 2027 before the LEVEL 2 trial reads out later in the decade. It would seem to me that, that might be possible, obviously, depending upon the magnitude of benefit, but considering the unmet need.

And then second, could you talk a little bit about the method of use patent protection, which appears to me to be very solid, but I think it would be helpful for you to characterize why you think it will be fully blocking and the duration of that protection.

Okay. So regarding accelerated approval, it seems very attractive. And one might argue, given the fact that this is a serious, potentially fatal disease with no treatment, it would depend on the effect size of the LEVEL trial. A very robust improvement would be a powerful stimulus to -- for the agency to consider this, but you also need to remember about the requirements for a safety database. And even though this drug has been used in 20 countries for 25 years and has an excellent safety record, the use has been short-term IV for heart failure.

So I can't speak for the agency, but my sense is they really want a robust safety database because there are so many patients who may end up taking this drug due to the fact that it will be oral and effective. So David, I can't really -- I don't really have a sense at this time. I think we'll wait for the level trial readout and then we can have some discussions and get a better sense to that. But at the present time, at least from the company side, we're anticipating going through both trials and then submitting at that time.

Now regarding the patent status, we have four patents. The patents are method of use patents. They essentially patent the label. So they're indicated for HFpEF, PH-HFpEF, they're indicated for any formulation, IV, oral, subcu, et cetera. They run into 2040 and with a patent extension would give us another few years on top of that. We have been told from experts who've looked at that those patents seem to be very solid. So I think our patent estate is pretty strong here.

And then just a follow-up, could you just articulate briefly why the patent estate is so solid for method of use patents?

Well, it covers not only levosimendan, but levosimendan with other drugs. So if someone were to get an indication of HFpEF or PH-HFpEF, it's extended over both, that would be a violation of the patent. So that would limit competitors only to development of a drug for PH-HFrEF, if you wish, or HFrEF by itself. And that I think is what -- is where we're focusing. We are not even trying to say that we're going to look at any other features of this heart failure community other than HFpEF and PH-HFpEF. And as I say, because of the multiple patents, which covers routes and doses and combinations, we think it's very strong.

The next question comes from Yasmeen Rahimi with Piper Sandler.

Thank you so much for the detailed discussion from Dr. Borlaug and Dr. Shah. Wonderful to hear your voices on the call. A few questions. I think the first question was how patients are feeling really well when they were part of the HELP study. So I just want to get a view on, as Dr. Shah and Dr. Borlaug, you're involved in the LEVEL-1 study, you're seeing the same phenomenon on patients feeling and functioning better or expressing that. Obviously, you don't know who's on the therapy. But if you could maybe voice over your commentary that you're seeing so far, that could be really helpful. That's sort of question one.

Question two is we often get is given that there is -- we went from an IV dose to an oral dose in the LEVEL study, a lot of investors try to understand the switch between these formulation if it could introduce any variability or any -- I guess, help us understand sort of like the translation and feeling confident that the change still predicts a high probability of success. And then the third question is to Dr. Borlaug. Do you have a good grasp on whether the difference or relaxin, as you know, Lilly has one that they discontinued, Astra has one, and Tectonic. How do these constructs differ? And is it more about patient selection? Is it the biology? Appreciate any color there.

Okay. So let me -- let the first one go to Dr. Shah because Dr. Shah also was an enroller in HELP and has been a very active enroller in LEVEL. So Sanjiv, do you want to share your feelings about what the patients are telling you?

Yes. I mean it's kind of phenomenal. I mean -- so you're right, we are blinded for the first 12 weeks, but then the patients undergo a few weeks where they go a washout and then they go into the open-label extension. So in the LEVEL trial, we now have a lot of experience of patients being on the open-label drug. And we always have to remind ourselves that there's potentially a placebo effect and they're unblinded. We are all unblinded when they go on open label. But we see things we never see in trials unless they're like positive in a positive way. Like -- so sure, when you unblind, you do see a bump up in patients who feel better now that I'm on the real thing. But what we've seen, which is really interesting is we saw patients who felt better during the randomized phase and then they go -- they wash out for 2 weeks and they feel worse again, and then they start feeling better again.

So I think that this is kind of what we saw when we did the IV to oral transition in the previous HELP trial. So it's very promising. I mean I'm not going to pretend that there's -- that this is definitive by any means. But I have to say, I mean, it's rare in patients with HFpEF, especially PH-HFpEF, where they're really debilitated, that anything makes them feel better. So that is -- it's quite different than other medications we've seen in this patient population.

So regarding the transition to oral, we have a lot of legacy data, including a MAD study that identifies what the level of the 1896 is associated with the oral dosing. And an early MAD study suggested somewhere between 1 and 4 milligrams a day would be the ideal. We then have a lot of chronic data on the metabolite from the two long-term oral studies, knowing at what level we would kind of want to target in the patients that were in the health trial.

When we did the oral transition, we up-titrated from 1 to 2 to 3 milligrams a day over 2-week intervals and measure those metabolite levels as well. And so seeing comparable levels of metabolite at the levels that we would anticipate to be therapeutic is giving us the confidence that we have the right dose. There is no problem from the metabolite because the levosimendan itself is highly well absorbed. And the metabolite is predictably produced in these patients reaching steady state over 2 weeks.

So we really feel from the PD/PK standpoint that we have hit the ideal dose. The dose also is a little higher than was used in chronic heart failure studies before because the patients weigh more. And remember, IV is weight-based where oral is standardized. And so we wanted to cover that potential gap as well. And Barry, do you want to answer her question about relaxant?

Yes. I mean, first, just to expand on some of the earlier, we -- some of the stories are just really outrageous. I mean people that have been like converted to becoming totally sedentary, men are out there in the fields, shooting dear and dragging the buck carcass all the way back to their truck and stuff like that. And women just telling me these stories that they're just life and day, just really life altering, that word is used.

And as Sanjiv says, I mean, we're unblinded in the open-label extension, but I mean, I can't tell you how many times people have said, I'm feeling a little worse because in the open-label extension, you go back down to b.i.d. dosing, twice daily dosing before you go up to 3x a day. And they'll say, I'm feeling a little worse than I was a couple of weeks ago, but I'm still better than the start of the trial, and then they get back up to 3x a day and they're feeling better. So it really -- again, it's -- you've got to always take it with a grain of salt when it's unblinded and the placebo effect is real. But really, I mean, it's quite convincing to me.

In terms of relaxin, there are different formulations. They have different pharmacokinetic properties. They're attached to different molecules that allow for the longer half-life, basically, so that you can give it once a week. But fundamentally, this is all human relaxin. Every one of these different molecules is human relaxin. It's not like some kind of close receptor agonist. It's just relaxin that's attached to like in the Eli Lilly compound, a formulation of albumin. So I just don't -- I don't think it's going to be that much different.

Now some of the companies, I think, are using different dosages. It's possible that could be different. We'll see. And the patient population in the volenrelaxin trial, we enrolled patients with a recently decompensated state. We did that because we thought that would have the best chance of success. Relaxin also improves renal blood flow and we thought GFR, and there was a signal for that in the trial. And we know that patients with recent hospitalization, that's a really sodium avid state, meaning those patients are very congested. They're really holding on to sodium. So we wanted something that would improve kidney function and reduce that sodium avidity or that proclivity to sodium retention. So we thought that, that was the right choice.

In the end, it might have allowed us to see a signal a little easier by selecting that patient population. But I think if the drug is worsening congestion in anybody with HFpEF, yes, if you take somebody who is ambulatory, far away from the hospital, they're going to have more reserve to handle any sort of volume accumulation that you would get from a relaxin, assuming that's what is doing, but it's still not going to be a good thing. And eventually, I would imagine that it would promote volume retention. But we'll see. We have to look at the totality of the evidence. There'll be more data coming soon. I'm really [Technical Difficulty]

I think we lost Barry.

Are you still on?

I'm still here. I just finished -- I don't know if you heard what -- I kind of ended on and I'm excited to see the other data when it comes. We'll see.

[Operator Instructions] The next question comes from Matt Phipps with William Blair.

Thanks for the very comprehensive walk through PH-HFpEF. Dr. Borlaug and Shah, just curious, what do you -- what would be your expectations for a patient on placebo, not treated with anything for like a 6-minute walk decline over a 12-week period? And then similarly, like what would be a level of 6-minute walk benefit that would get you excited? I mean there's obviously plenty of anecdotes, I guess, to get you excited, but just on that point specifically, maybe.

I think a decline -- I mean, there's always going to be a little bit of noise, especially with small sample sizes and individual patients are like five patients, you may see some people that just decline and it's just sort of noise. That's why we have to do larger trials. So we kind of eliminate that noise and we can see the signal. I think -- what level gets me more excited? I think like a 20-meter improvement would be really phenomenal. That would be something that I would consider to be very, very significant. If it's more than that, then the enthusiasm just continues to grow. But I'd say at least 15 to 20 probably would be what I would be looking for.

Yes. I think we have to think about it differently than pulmonary arterial hypertension, where the standard has been 30 meters because like even GLP-1 receptor agonist which caused a tremendous amount of weight and did a lot to help these patients in both the STEP-HFpEF and SUMMIT trials, it was only about 20 meters. And so here, we're not -- the patients aren't losing a ton of body weight, which plays into 6-minute walk distance a lot. And so 20 meters, I think, 15 to 20 meters would be really remarkable. And that's the kind of improvement that we see and patients are like -- they really feel it and they tell you about it.

I think that interesting thing happens, I think in most HFpEF trials and heart failure trials, there's a bit of a placebo effect and patients just being better when they're in trials. So their 6-minute walk distance, their KCCQ, the lower it starts out, the more it kind of improves during their -- even if they're in the placebo group and stuff like that, we see that -- but in PH-HFpEF is the most severe form of HFpEF. And you do see in severe disease, you see progression and you see progression of RV failure over time in HFpEF.

So it's conceivable that there are patients who, like in transthyretin cardiomyopathy, they're actually worsening. They're in the part of the disease state where they're actually -- no matter what you do, they're worsening. So you sometimes get very sick patients like that. But I think the majority of worsening even on a placebo is what Barry was saying, like you get these patients, they might come in one day and they're depressed or something, their spouse passed away or something. And these are real things that happen. So I think that's why we always push for adequately powered larger trials to make sure that what we're seeing is real.

That's really helpful. And kind of on that front of the PH-HFpEF versus HFpEF, I get some questions from investors when they're looking at this space of the SGLT2 class or recent approval for none. I mean, obviously for HFpEF and I guess, some different definitions there. But do you see those playing a role in this patient population? Would this be something you'd use on combination with levosimendan? Just curious if there would be any overlap.

Yes, I think definitely. Sorry, Sanjiv, go ahead.

No, I think we're going to say the same thing. You'd use this on top of those. I mean they're totally compatible and those are sort of standard of care and finerenone is really, I think the data is best for like -- in terms of it being better than spironolactone or eplerenone is in lower GFR as lot of these patients have cardiorenal syndrome. So yes, we'd use it on top of those.

The next question comes from Seamus Fernandez with Guggenheim.

This is Colleen on for Seamus. Maybe first, I was wondering if you could talk a little bit more about any learnings from the REBALANCE trial that might relate to LEVEL. Are there any differences in the patient population or trial design we should all should be thinking about? And any concerns with hypotension? And then secondly, can you talk through how or why over-indexing on the HELP study not achieving stat sig on the primary endpoint is likely flawed and the difficulty of that endpoint?

Yes. I mean I can take the first one. The Axon trial, when we were designing it, it was like I mean it was a totally revolutionary like going in there and ablating the splanchnic nerve. We really didn't know who it was going to help. I mean there were reasons why we thought it might help people at the earlier end of the spectrum of HFpEF, the so-called exercise-induced left atrial hypertension, where the pressures are normal at rest and go way up with exercise.

And then there were reasons why we thought it would help patients like those we enrolled in help with very high right atrial pressures, PH-HFpEF, maybe CpcPH because they also have very high RA pressures. And so you're reducing the -- we thought we might be reducing the resting sort of splanchnic vasomotor tone and things. And I think -- so if you want to think about differences, it was that the HELP patient population was a subset, same with LEVEL, it's a subset of a more broad population that we enrolled in the REBALANCE trial with AXON.

And what we saw there is something that is really, I think, to me, apparent now that I've done all these trials and I think about it when I see the patients in clinic. There are some patients who are pre-load insufficient. So those patients are -- they -- and COVID can do this autonomic dysfunction, diabetic neuropathy, Parkinson's. It's basically like they're the patients who -- they've got this syndrome, but they can't get out of bed without feeling lightheaded and dizzy. Their right atrial pressure is normal usually. They're not the HELP, they're not the LEVEL patients. They're not the ones that we want.

Then there's patients who are preload dependent, meaning that if you don't do anything else and you just drop their preload, they're going to feel like crap. They still might have a less number of hospitalizations for heart failure, but they're going to feel like crap because they depend on their preload to augment cardiac output to fill a very stiff ventricle and you're not doing anything else for them. And then there's the final group, which is a large group. I mean it's what I call the preload overload. And that's what we were studying in help.

And that's the kind of patient who has a very high right atrial pressure and they're kind of -- they've got way too much preload and reducing it with levosimendan helps. But even if they were sort of edging into that preload dependent state where they're like got a sicker right ventricle, that's what I was talking about earlier. I think that levosimendan is doing other things to improve right ventricular function and in that way, has some advantages over things like splanchnic nerve ablation.

So I'll address the question about the endpoint issue in the health trial. So for those not familiar, we identified the drop in pulmonary wedge pressure during peak exercise as the primary hemodynamic endpoint for the health trial. So we were faced with several challenges. The first one is that intravenous levosimendan had never been given to anyone outside of an intensive care unit. And here, we were giving it at home to patients with a home infusion pump and a permanent IV line. It would require the patient to be homebound for a day.

We knew that the half-life of the active metabolite was about 4 days, but we didn't know what kind of carryover effect we might be able to anticipate by giving it once a week versus twice a week. Going back and forth, we thought twice a week would be difficult for the patients to adhere to, even once a week asking that to doing was tough. And so we had -- and we did not have any access to oral. So we planned it thinking that if successful, we would go with IV into the Phase III trial. Agency would want to see trough levels from the IV to see about efficacy. And so the design was to give it once a week IV and measure their hemodynamics and 6-minute walk at the end of the week.

Now what you've heard from both Dr. Shah and Dr. Borlaug is that many of these patients were very sensitive to the dose that they were getting in that when they were on the 2-milligram dose, they were less robust, a little more shorter breath, which improved at the 3-milligram dose. So I think it's no surprise that at the end of the week when we did the 6-minute walk, and the hemodynamics that even though the wedge pressure at rest and with legs up, which is a stress, had the same effect, it diminished itself when it went with peak exercise.

And I attribute that to the fact that they didn't have enough drug on board. So we don't look at that as a failure of the drug. We look at it as part of the design of the trial that allowed that to emerge. We also did a mixed model assessment of the wedge pressure at 6 weeks with rest and exercise, and it was highly significant there. But the data is the data, and we don't hide from it. I think what the data just educated us to is that we needed a drug that had longer-acting efficacy and the oral was the solution.

Yes. I'd add on that the data quality can be a little worse during exercise. Patients are -- they're breathing heavy and heart rate is fast. They're breathing rapidly. It makes it a little bit more difficult. So just the signal is maybe a little bit clearer at rest when they're totally relaxed and then feed up, they're still relaxed. They're still breathing normally. So that also might have contributed to the inability to see the effect. But I think that's a lesser effect than the fact that the drug was at trough levels, like Stuart mentioned.

Although it was interesting, Barry, that the central venous pressure was the same at exercise. It had the same treatment effect. So it kind of tells you, I think, that it's the left-sided wedge pressure that's the hardest target to treat, which we thought going in.

This concludes our question-and-answer session. I would like to turn the conference back over to Chris for any closing remarks.

Thank you, Betsy. Thanks, everyone, for joining us today, especially Dr. Shah and Dr. Borlaug, who took time out of your extremely busy schedules. And thanks to all of the questioners. We really appreciate the thought that you guys have given this. So the goal today was to address some of the most frequent questions we get on our program and on levosimendan, and you guys have really illuminated some of the key areas of inquiry. So thank you.

It's an exciting time for Tenax to be at the forefront of an evolving field where there is so much unmet need. And we talked a lot about different strategies today. The trials over time will inform us if there is a single new solution, if there are two solutions, maybe complementary solutions. So -- we're looking forward to the time and the trials answering these questions. So thank you again to everyone, and we look forward to speaking to you in the future.

The conference has now concluded. Thank you for attending today's presentation. You may now disconnect.