Hello, welcome to this latest in the series of Fireside Chats here at the HCW BioConnect Conference. My name is Ram Selvaraju. I'm a Managing Director and Senior Healthcare Equity Research Analyst at the firm. It's my pleasure to introduce the next company, Entrada Therapeutics, which is traded on the Nasdaq under the ticker symbol TRDA. Here with me today is Nathan Dowden, President and Chief Operating Officer. Nathan, it's a pleasure to have you with us.
It's great to be here, Ram. Thank you very much. It's great to be back. I think this is, what, three, four years now? It's wonderful to get the invite again.
I think maybe it would be helpful to our audience if you could just run us through the key technology platform of Entrada, which is centered around a type of moiety called Endosomal Escape Vehicle or EEVs, and then maybe we can get into some questions around Entrada's activities, particularly in the Duchenne muscular dystrophy space.
Sounds good. Thank you very much. Endosomal Escape Vehicles are small cyclic peptides that we conjugate chemically to oligonucleotides, to proteins, et cetera, for a variety of different therapeutic applications. What differentiates the EEV, this particular cyclic peptide, is that it enables a tremendous amount of endosomal escape. For people who are familiar with the challenge of getting biological material into the cytosol and into the different organelles that you'd be targeting from a therapeutic perspective, what you know is historically you can only get about 1%-2% of biological material into the cytosol itself. Everything else gets either stuck on the surface or fails to escape the early endosome and gets processed through the lysosome.
What that means is, effectively, our therapeutic index, once we actually get to the cell, is significantly higher than anything anybody has ever done, has ever developed before. And we've seen that across a wide range of preclinical models and across a wide range of therapeutic applications. From the perspective of the simple math, we get about 90% of biological material into the cell after about 24 hours, and we get about 50% of that out of the endosome into the cytosol. When you just do the 50% versus 1%-2%, that's an easy win from a therapeutic index perspective.
Now turning to DMD. Many in the audience may be familiar with DMD. It's clearly one of the most well-known rare disease indications out there, clearly a debilitating, chronic condition. In particular, Entrada is unique because it is effectively developing a whole suite of exon-skipping candidates, and the lead of these recently produced the first clinical efficacy data in a phase I/II study. In your Cohort 1, you had reported plasma Cmax and AUC relative to healthy adult volunteers, and you had previously reported data in juvenile NHPs, non-human primates. I was wondering if you could walk us through the updated juvenile versus adult PK ratio and how that translates into the expected muscle tissue exposure in Cohort 2, which is gonna be the next cohort that you report data on.
For those in the audience who aren't directly familiar with this, Cohort 1 was at 6 mg/kg, right?
That's correct, yeah. 6 mg/kg . Just to take a quick step back, and to talk about the trial design overall. This is a multi-ascending dose trial, we're looking at 6 mg/kg , that was the data that we read out. We're currently dosing patients now at 12 mg/kg , the second cohort is dosing at 12 mg/kg. We've got license to go up to 18 mg/kg based on the chronic toxicology that we ran. Basically we're right in the middle of the trial. With respect to the first cohort of data, again, lowest dose, we based the starting dose on the healthy normal volunteer data that we read out in 2024.
That data looked quite good, and what we were excited about with respect to that data was that we saw no renal biomarker signals. For people who are familiar with this space, one of the issues with the oligonucleotide-based therapies, and particularly those that have been conjugated to linear peptides, to the first generation of peptides that were supposed to effectuate cell entry, is that they generally suffered renal toxicity. That was a big question. We thought with the NHP data that we had answered that question. People came back to us and they said, well, that was a single ascending dose study, and those were in healthy volunteers. What about patients? What about multiple doses? Fair question.
We're really happy to be able to present the fact that, with multiple doses in these patients who are, who are quite sick, we saw no movement in those renal biomarkers of interest whatsoever. You can see that in our corporate deck. We've actually shown patient-level data, and the reason we were able to show patient-level data without breaking the blind, is because you can't tell who's placebo and who's a patient. Nothing moved there. That's eGFR, that's cystatin C, which is your, probably your most sensitive biomarker you're looking at. Also, people had questions with respect to magnesium levels because that's been a real challenge for folks in the past. Magnesium levels didn't move. It looks really, really clean, so we're excited about that.
The next question was, okay, you've got great safety. The renal safety was good. By the way, in terms of adverse events, everything was mild, moderate, very well tolerated. Really happy about that. The question was, okay, dystrophin levels, exon skipping levels, where are you with that? Those came in lower than we had expected. When we went back and we did a retrospective analysis on this, hindsight's always 20/20 obviously, what we saw was the plasma Cmax and certainly the plasma AUC in the pediatric patients was quite a bit lower than what we'd seen in the healthy normal volunteers. You do generally allow for some allometric scaling between adults and juveniles, but this was a little bit of a surprise to us.
The other challenge we had is when we had been modeling, we were looking at the healthy normal volunteers because that's the data we had, and actually adult NHPs, because again, at the time that's the data we had. That's what we were using for our sub-chronic toxicology. Those numbers looked similar. Right on top of the pediatric data, we got our juvenile AUC numbers, and those were also quite a bit lower. What we see now, which we're now effectively correcting for as we think about our modeling is, you get about half the exposure in whether it's a pediatric patient or whether it's a juvenile NHP versus an adult of same species.
When we model that out, the key takeaway there is, and that's a long explanation, but there's no way around it, is that effectively what we're looking at is a right shift, we think, in terms of the efficacy. I say that because when we go back and we look at this juvenile NHP data and we looked at the, we looked at the plasma exposures, and we also looked at the exon skipping associated with that. The level that we expected to see in our first pediatric cohort based on adults is the level that you see in the second cohort in your NHPs. Everything just right shifts.
That's why we're excited and we're relatively confident that when this second cohort at 12 mg/ kg reads out at the end of the year, that's where we should basically see a jump across the threshold when it comes to AUC levels, but most importantly, exon skipping and dystrophin production. As I said before, that's our Cohort 2. We're also potentially able to go up to 18 mg/kg in a Cohort 3. Hopefully that's helpful.
Very helpful. Turning now to the functional data that you saw. You know, you have a statistically significant time to rise velocity benefit. Clearly in DMD historically, the correlation between increases in functional dystrophin levels and functional benefit has not always been particularly tight. Ultimately, at the end of the day, what matters most to patients is functional benefit. I was thinking that it might be helpful to walk us through some of the aspects of the functional benefit data that you've seen, the degree to which this potentially feeds into what you might identify as a potential approvable endpoint in a registrational program, and also the mechanistic case behind this, particularly from this perspective of satellite cell engagement.
Sure. Happy to. Yeah, we were pleasantly surprised that we saw a signal, that's ultimately what matters to the patients and the physicians, I mean, at the end of the day. You know, we've gone out, and obviously, we engage with the community all the time. And we've talked to a lot of KOLs, a lot of treating physicians, and what they tell us to a person is function's what matters. Safety and function. I was talking to one KOL a couple of weeks ago, and he said, you know, you guys care about dystrophin, and I understand why, because you need that to get an accelerated approval. If we don't see function, it's at least a harbinger that maybe we will see function down the road.
Ultimately, I treat a patient, and what I care about is function. From the perspective, just to get to the end there for a sec, from the perspective of an accelerated approval, what the FDA asks for is a statistically significant improvement in dystrophin and then a trend towards function. That's all you have to hit. It's kind of an intermediate step, and it's one that we fully expect to hit in Cohort 2. This time to rise measure was really exciting. To take a step back again, what you expect to see based on the signals that come first, second, third, fourth, as you're treating these patients is you expect time to rise to move relatively quickly. Time to rise, and this is time to rise from floor.
This is basically a child who's sitting on the floor who's told, stand up as fast as you can. They're not allowed to use any support whatsoever. There's no parent in the room. There's nobody cheering them on. It's under GCP conditions. It's very tightly controlled. They time it. It's one that's been shown to be extremely robust in terms of predicting functional decline. Now, some issues you can have with time to rise are you can get a relatively large distribution with fat tails as you might imagine, right? You have a nonlinear decline in the patient function. From a statistical perspective and from a registrational endpoint perspective, what agencies actually prefer is something called time to rise velocity, which is just the reciprocal. It's one over time to rise.
It gives you a number in rises per second. What that reciprocal does is it basically takes a little bit of a noise out of the measure. It brings it back closer to a normal curve, and it allows you to deal with this a little bit more effectively statistically. Not only did we see statistical significance in time to rise, but also in this time to rise velocity, and it was a very strong signal. When we looked at the number, and I know this is eight patients. It's our first cohort. It's our lowest dose. We're humble in the face of biology and statistics, but it's a big number. We compared that to, for instance, what vamorolone was able to show, and that's a registered product.
The physicians tell us, you know, do you know why we use steroids? Because we know they work, because they improve function. That vamorolone number versus placebo was 0.06, and we were able to show 0.09 at our lowest dose. There's a lot of excitement around that. Sarepta has actually put some supplemental information into the FDA. They were able to show a number. It was closer to 0.05. Dyne in their phase I/II trial looked at this metric as well. They were able to show an improvement versus placebo. Again, that was 0.05. We're feeling pretty good about this number. The question is, right, why? How did you show this number with a, with a relatively low dystrophin level? The overall dystrophin level, by the way, was about 6%, so not nothing.
That can be fairly significant in terms of the lifetime of a patient. If you compare a patient, for instance, who's a 44 skip amenable patient who has 6% dystrophin, and a patient, let's say untreated, who's 51 skip amenable who will have almost no baseline dystrophin, you'll see about a 4.5-year difference in terms of loss of ambulation. 6% is meaningful clinically. The question is, okay, the improvement was only about 2.5%, so what happened? One thing we've always talked about as a potential differentiator is our ability, we believe a unique ability maybe to get to the quiescent satellite cell. What people forget, and it's completely understandable, is dystrophin plays two very important roles in the biology of DMD.
The one role that everybody keys in on, and rightfully so, is as a shock absorbent to protect the membrane of the muscle as it undergoes contraction. The other really important function that dystrophin plays is it enables the proliferation and differentiation of muscle stem cells, the regeneration of muscle. These satellite cells, they live in highly vascular niche right alongside the mature myofibers. They get bathed in blood all the time, and they're basically there ready to go when the trophic signal goes out from the muscle that it's been damaged. They're supposed to proliferate, they're supposed to differentiate, and you're supposed to create new muscle. In these DMD patients, that's something that's significantly impaired because there's no dystrophin in that stem cell. What if you had dystrophin in that stem cell? You've now basically corrected the regenerative capacity of that patient.
Why might you see function before you see the biomarker? You might see function before you see the biomarker because those stem cells that are bathed in blood, which are therefore bathed in drug even before the mature myofiber sees uptake, that stem cell is now ready to be activated. That stem cell is ready to proliferate, to differentiate, and to rebuild healthy muscle. It's not just about protecting the damaged muscle that's already there, which quite frankly is probably going to stop spilling CK into the blood, right? If you repair that muscle, but isn't going to get much stronger because it's damaged muscle. If you're replacing that damaged muscle with healthy muscle even a little bit, you should see functional improvement. That's the hypothesis that we're testing now. We're going back to the biopsies.
We're doing nuclear staining to look to see if we've got PMO, you know, in these centrally nucleated fibers, so in these satellite cells, in the maturing myofibers before they become mature myofibers. I think if we see that, and we see replicates because we've got our Cohort 1 45 data coming out in midyear this year, which will be really exciting, that's a program we're really excited about for a variety of reasons. We have our Cohort 2 data coming out at the end of the year, we'll see if there's a dose-dependent relationship here, or at least there's a replicate. We also have our open label data coming from this Cohort 1 patient population. Patients, they've gotten three doses in the multi-ascending dose trial.
They're getting six more doses right now in an open-label trial, still blinded so that we can maintain because there are two placebo patients. The strongest data we should get is that crossover data, right, from those placebo patients. If that functional benefit is maintained or deepened, then I think there's a really strong case for this hypothesis. Then there's a potential to say maybe there is a bit of a paradigm shift here. Ram, as you said, nobody's really nailed down what is the relationship between dystrophin and functional benefit. It's not to say that dystrophin isn't important. Of course it's important, but everybody's using different tests, different assays, different patient populations, different genetics within the patient population they're looking at, et cetera. It's just noisy. What matters is safety and function.
You know, in that context, I wanted to ask about two other things. You know, it was previously noted that baseline dystrophin in both placebo and treatment arms from this ongoing study was lower than previously reported in competitive exon 44 studies, and that response generally correlates with higher baseline dystrophin. Since response typically correlates with higher baseline dystrophin, you know, why did these patients in your study run lower? You know, do you think that this was a function of biopsy site or other aspects of the methodology? To what extent how does this position your program relative to competing programs, particularly the golodirsen class assets and moxeparvovec? Does it make cross-trial comparisons more difficult? I would imagine that it does. The other question, again, relating to dose. You mentioned earlier the exemplary renal safety profile that you have.
What I'm wondering is, how are you thinking about the 6 mg/ kg dose at this point in terms of, you know, whether or not this would be definable as a minimal effective dose? How are you thinking about future long-term dosing flexibility given the fact that, you know, there are only two other doses scheduled to be studied in this trial? You know, given the renal safety that you have, you know, does this potentially point you to flexibility in terms of being able to go even higher if, you know, that were warranted?
Gotcha. Gotcha. Lots to unpack there. Let's see. Let's go back to front. Again, right now with the multi-ascending dose trial, we've got six, 12, and 8 associated with that trial, and we're continuing to dose the 12 mg/ kg right now. We're really excited to see, you know, what data comes from that. I think to your next question with respect to what do we think our registrational dose will be and what will we take forward in a confirmatory trial, let's see. Again, to your point, it's not just about the dystrophin, right? Do we need to see 30% dystrophin, 20% dystrophin, 15% dystrophin over baseline?
Well, I think it's going to depend on what functional signals we see and how those mature. Because you don't need a quote-unquote competitive dystrophin signal to register the product. What you need is a competitive functional signal to market the product once you're actually out there in market. We'll see on the 12 and 18 and if we want to go any higher. I can't really speak to that yet. You know, with respect to going back to, you know, what's the design going to look like, you know, there are a number of trials ongoing right now or about to start up where time to rise velocity is the primary endpoint in the phase III trial.
I think the fact that we've got a signal there is extremely helpful and we're hoping we see a lot more of that, and that gives us some confidence that, you know, once we go through the accelerated approval process, we'll be in good stead to have a discussion with the agencies about, you know, potentially using that as a primary endpoint. But again, we'll see. There's a lot of water to flow under the bridge before we get there. Sorry, what was the rest of your question?
You know, it was also about the baseline dystrophin levels.
The baseline dystrophin. Yeah. The challenge that you have here, right, is with respect to accruing the clinical trial, you get what you get to a certain extent. People have asked us, well, could you have inclusion/exclusion criteria that sets a lower bound on, you know, the dystrophin level that you get? Well, that would be difficult 'cause you don't know until you actually take the biopsy, right? Number one. Other people have said, well, what about the genetics? You can get different responses depending on the genetics of the patients. That really wouldn't be ethical. You do get what you get.
It is a very, very good point that I think if I remember correctly, across all the different trials that different competitors have run in exon 44 specifically, I think the range has been somewhere between 5% and 8.5% in terms of baseline dystrophin, and we know for a fact that the response is dependent on baseline dystrophin levels. Ours did unfortunately come in quite a bit lower, and so that probably did impact response. How much? I couldn't say. We couldn't possibly model that. Again, let's see what Cohort 2 brings.
This is just a question that I think, you know, some folks have probably previously asked, just given the nature of DMD and the fact that there's been a long history of accelerated approvals and kind of, you know, fast path to market in this indication, and there still remains obviously a very clear unmet medical need. If you were to see a meaningful functional improvement in Cohort 2, would that potentially lead you towards filing a registrational study plan at that juncture? Or is it the intent to wait until you have data from Cohort 3 as well?
Yeah. No, it's a great question. I think it's entirely possible. Again, if the dystrophin level looks like it's high enough to meet the bar from an accelerated approval perspective, and we're showing really robust functional benefits that we think could be meaningful for patients, I think there'll be, you know, there'll be a big push, not just from within the company, but from the patient community to get the drug out there and make it available as fast as possible. Yeah, we'll see.
Maybe you can just run us through kind of the cadence of data catalysts and clinical trial starts that you anticipate with the remainder of Entrada's exon-skipping portfolio, and also provide our audience with a sense of how comprehensive this portfolio would ultimately position you to be in terms of being able to address comprehensively all of the subpopulations within DMD.
Yeah. Yeah. As mentioned before, there's still a lot to come in the second half of this year, so we're really excited about it. Sticking with the 44 program, Cohort 1's read out, Cohort 2 by the end of the year, the open label associated with Cohort 1 by the end of the year. That's, that's gonna be safety and that's gonna be functional benefit. There are no more biopsies coming, that'll be safety and functional benefit. We're really excited about that. In the middle of that whole period, we should have the Cohort 1 from the 45 program. As you know, the bar for that from a competitive level is very, very low.
We're very excited to see what we get out of the 45 program, even in the first cohort. That's coming midyear. Then there's the Vertex partner program, VX-670, where they've now said they are gonna read out in the second half of the year. I think we're all waiting with bated breath on that one, because that's a very large global trial and a very large indication and it's a significant go-forward partnership with those guys from the perspective of economics. We're excited about that. You know, beyond that, we've got the 50 program and the 51 programs, which will round out the portfolio.
Ultimately, yeah, to your point, Ram, I think what we're excited about is nobody else is really pursuing the full portfolio in DMD at this point from a go-forward perspective. Nobody's, from the peptide perspective, has shown the renal safety we've shown. Nobody has shown early markers that are statistically significant of functional benefit as we've shown with this 44 program. There's a lot to be excited about. There's a lot to come, and we're looking forward to the rest of the year.
Just to wrap up, wanted to make sure I touched upon your endeavors in the ophthalmology space, and wanted to see when we might see a lead candidate progress into the clinic, particularly because obviously the eye is a surface organ. You know, there are lots of unmet medical needs within ophthalmology. Those are readily definable and evaluable, objective, and efficacy endpoints for the most part. Maybe you could talk just a little bit about Entrada's efforts in ophthalmology, particularly with the ENTR-801 candidate and, you know, when you expect that to be in the clinic, and I think that'll wrap us up.
Okay. Yeah, sure. These are preclinical programs, we haven't talked a lot about them. To your point, we've got ENTR-801, which is being developed for Usher syndrome type 2A. Fairly significant population, tremendous unmet need, basically nothing in development at this point in the clinic worth speaking about. You know, far from the perspective of the biology, the signals look quite good. The plan is to talk more about how that's gonna progress through next year. We also have another candidate in a very similar IRD that we expect to announce very soon. We'll be starting to build a portfolio of those ocular diseases as well.
To your point, with respect to some of these IRDs, the unmet need is tremendous. There's very little investment that goes into these vis-a-vis some of the other, say, the neuromuscular diseases, for instance. The competitive space is wide open, we've taken strategically the same approach we've taken with some of the neuromuscular disease. We've looked for extremely high unmet need, competition that clearly isn't meeting the bar, and a space where we know from the perspective of the biology, we have a competitive advantage that we can bring forward. That's really been the focus with ocular. More to come there in 2026, 2027.
Nathan, thank you so much for sharing, salient aspects of the Entrada story with us, and, thanks to our audience for their attention.