Good morning and welcome to Sarepta's EMBARK three-year data top-line results call. As a reminder, today's program is being recorded. At this time, I'll turn the call over to Doug Ingram, Sarepta's Chief Executive Officer. Please go ahead.
Thank you very much. First, before we begin, I must remind you that we will be making forward-looking statements today, so please review our various public filings for the risks and uncertainties that come when one makes statements like that. Now, with that, first, thank you all for joining us as we present the three-year top-line results from EMBARK, which is the ELEVIDYS Phase 3 pivotal trial. The results from EMBARK year three are remarkably important. While we have seen longer-term results in Study 101, a small four-participant proof-of-concept study, the results discussed today are the first time in history anyone has measured the disease-modifying impact of a gene therapy over a three-year period in a large, well-controlled clinical trial. ELEVIDYS is different than some other therapies.
It works not by providing palliative relief only, but by generating a functional shock-absorbing form of dystrophin, the goal of which is to restore protection to the muscle and thereby modify the trajectory of disease. With three-year results, we can confirm not merely the benefits of the therapy, something we have done repeatedly in past readouts, but we can test whether those benefits meaningfully diverge and widen against natural history over time, something one would predict for a disease-modifying therapy. That test has implications for the long-term value of commencing ELEVIDYS treatment as soon as reasonably possible to change trajectory and to avoid the irreparable damage that occurs daily without disease-modifying treatment. Now, with that, I will turn the call over to Dr. Louise Rodino-Klapac. Louise.
Thank you, Doug. It's a pleasure to be here today to share the newest results from the EMBARK study. Next slide, please. As you will have seen in our press release that was just issued, top-line functional results in patients who were treated with ELEVIDYS in EMBARK Part 1 demonstrate a dramatic shift in disease trajectory after three years. In a few moments, Dr. Richardson will take you through the data in detail. But briefly, on average, ELEVIDYS treated patients remain above baseline three years after treatment, as measured by the North Star Ambulatory Assessment, or NSAA. In addition, ELEVIDYS treated patients have a 70% or greater reduction in disease progression relative to the propensity-weighted external control group. This is measured by time to rise and 10-meter walk/run.
This is long-term data in a robust controlled clinical data set and demonstrates the power of a disease-modifying therapy targeting the underlying cause of Duchenne. These statistically significant benefits not only persist but continue to strengthen over time, creating a sustained and growing separation from the expected disease trajectory and the known relentless decline from Duchenne. Understanding the disease trajectory is important. Next slide, please. In Duchenne, the course of the disease follows a well-understood and predictable path of decline, as shown here via scores on the North Star Ambulatory Assessment, a composite measure of motor function skills. Individuals with Duchenne typically reach their peak physical function around age 6 and then decline as a result of increasing fibrosis, decreasing muscle mass, and waning regenerative capacity.
The aim of dystrophin restoration treatments like ELEVIDYS is to alleviate this constant downward pressure on the development and maintenance of these skills that produce this curve. Next slide, please. As mentioned, Duchenne occurs because of the relentless underlying muscle pathology, including muscle fiber loss and corresponding fat and fibrotic replacement. This process begins before birth and progresses over time, as shown in these cross-sectional images of skeletal muscle from one year of age to eight years of age. This again highlights the importance of early treatment with dystrophin restoration to slow this progression. Next slide, please. As shown in this slide, the goal is to stabilize or slow the decline resulting from the degenerative process of Duchenne. As a result, change from baseline alone is not adequate in measuring therapeutic benefit. Comparison to the expected disease trajectory is critical.
As illustrated in this graph, the therapeutic potential of dystrophin restoration is demonstrated and grows over time based on the divergence of the external control decline contrasted with the stabilization or slowing of progression in treated individuals. Next slide, please. We have the most comprehensive data set in Duchenne, with greater than 1,200 patients treated with ELEVIDYS clinically and commercially. ELEVIDYS has been dosed in a wide range of individuals from as young as two to adults with advanced disease. Next slide, please. As a reminder, EMBARK is a double-blind placebo-controlled trial with the primary readout one year following treatment. At the end of year one, the placebo patients crossed over and received ELEVIDYS, and patients already treated received a placebo infusion. And all patients received the per protocol increase in corticosteroids around the time of dosing. Participants, investigators, and the study team remained blinded for the second year.
After 1 year, an external control is required in place of placebo for comparisons as all study participants have now been treated. Today, we're sharing the 3-year data from participants treated in Part 1 that are now enrolled in the long-term extension study, Study 305. Next slide, please. Before looking to the new 3-year data, here's a reminder of the functional results for all Part 1 patients treated out to 2 years. All measures strongly favored ELEVIDYS and were statistically significant versus external control. The results, known as Part 2 from EMBARK, were just published in the peer-reviewed journal Neurology and Therapy earlier this month. Next slide, please. I'd also like to remind you of the muscle MRI data. Muscle MRI provides an objective approach to assess underlying muscle pathology, measuring the level of fatty infiltration and T2 signal to correlate strongly to and predict future physical function.
Lower levels of fat fraction and T2 indicate healthier muscle. In the absence of an external control, here we are showing the 2-year data in 2 representative muscles versus the 1-year placebo data. We see modest to no increase in fat fraction from baseline to 2 years, and levels at 2 years are well below what is seen at 1 year in the placebo patients. This is consistent across muscle groups. Even though you see that improvement in NSAA and other functional measurements, you see the impact of treatment being delayed even 1 year. The damage to the muscle continues, and you will never achieve the same level of fat fraction as patients treated a year earlier. We're pleased with the treatment effect in a blinded study and reconfirmed with MRI imaging. This highlights the importance of treating as soon as possible to preserve muscle. Next slide, please.
Over the past year, we've also presented and published cardiac MRI data through two years in EMBARK, which have no new signals, and cardiac function remains within normal range. Next slide. I'm going to now turn the call over to Dr. James Richardson, our CMO, to share the new three-year data from EMBARK in greater detail. James.
Thank you, Louise. It's my pleasure now to present to you the 3-year results from the EMBARK Part 1 treated patients. These pre-specified analyses take data from the complete 2 years of EMBARK and then the first year of our long-term extension study EXPEDITION, also known as Study 305. This is by far the largest long-term follow-up of patients treated with the gene therapy for Duchenne muscular dystrophy, and it's all conducted within the rigor of a clinical trial setting. Next slide, please. We compared the 3-year functional data from the treated patients followed within our clinical trials to a propensity-weighted control. As you'll know, propensity weighting represents the gold standard of external control analysis. The outcomes analyzed were NSAA, time to arise, and 10-meter walk/ run. This was based on the availability of these measures in appropriate external control data sets.
These three measures are well established as clinically relevant and highly predictive of future disease progression. Having served as the primary and key secondary endpoints in EMBARK Part 1, they were defined as the three co-primary outcomes in the pre-specified year two and year three statistical analysis plan. That plan also included all the technical aspects of the analysis, including the methodology and criteria for selecting the external control. The external control data themselves are taken from contemporary natural history of placebo-armed sources. All these studies were prospectively selected and represent current standards of care, including the use of chronic corticosteroid therapy. External control patients were initially selected out from this pool of data of over 1,200 patients based on inclusion criteria that align with the availability of the required data and the baseline characteristics of the EMBARK trial participants.
Individual weighting is then applied to their data to further prove the comparability of the treated patients. Next slide, please. This approach has yielded an extremely well-matched comparator, as you can see in the table on the left here. The table on the right shows that a large number of external control patients were available for comparison at each time point, further speaking to the rigor of these analyses. You may note that 11 patients did not progress from the end of the EMBARK study into EXPEDITION. Thorough analyses of these withdrawals provide no evidence that this introduced any bias in the subsequent analyses. Next slide. Beginning with NSAA, here we see a 4.39-point difference at year 3 between the treated and external control, with a highly statistically significant p-value of 0.0002.
This delta is a little under twice that observed at year 2, and a little more than twice over the published MCID. Even if we focus purely on the treated patients, we see that on average they're remaining above their baseline 3 years after treatment. As a reminder, the mean age at this point for these patients is around nine, an age within the natural history of Duchenne when most patients undergo a rapid decline in the NSAA. In fact, we can see this rapid decline if we turn back to the external control, who have lost nearly 4 points from their baseline 3 years prior. Next slide, please.
Moving on to time to arise, there is extensive published natural history work demonstrating time to arise as the most sensitive and earliest time function test to worsen in this age group, and that it is a significant predictor of loss of ambulation. The relentless decline of Duchenne is demonstrated by the progression of the external control group, whose time to arise, which at baseline was only 3.5 seconds on average, has now increased by a further 8 seconds. The resultant difference of 6 seconds between the control and the treated patients is again highly statistically significant, with a p-value of less than 0.0001. This delta represents a slowing of disease progression of more than 70% and a threefold widening of the treatment effect between the treated group and control since year two. Next slide, please.
As with NSAA and time to arise, we again observe the highly clinically and statistically significant difference in the 10-meter walk/ run assessment of 2.7 seconds, with a p-value of 0.0039. This represents an approximately 70% slowing of disease progression. And again, we see this widening treatment effect over time, with a doubling in the separation between the treated population and external controls between years two and three. Next slide. No new safety signals were observed in year three of this cohort, and no treatment-related serious adverse events were reported. This is consistent with our understanding of the safety profile of ELEVIDYS gathered through over 1,200 exposures in clinical trials and in commercial use. Next slide, please. EMBARK and the EXPEDITION study represent by far the largest long-term follow-up in a clinical trial setting of a gene therapy for DMD.
Using a pre-specified analysis, the results show definitive and profound slowing of the progression of the disease in patients who are now, on average, approximately nine years of age, time at which the untreated natural history is one of significant loss of function. On NSAA, in stark contrast to the predicted trajectory, patients remain above their baseline three years following treatment. Disease progression, as measured either by the time to arise or 10-meter walk/ run, is being slowed by approximately 70%. Equally important, there are no new safety signals. Long-term follow-up of patients will continue, and we'll work to present and publish these data and more data in scientific forums. While the data provide us with powerful information to inform changes in how we treat disease, none of these results are possible without the individuals and their families who participated in our studies.
We are incredibly grateful for all of their contributions, along with the contributions of investigators and site teams and my fellow Sarepta colleagues, who continue to inform our understanding of Duchenne and ways to change the course of this terrible disease. With that, I will turn the call back over to Doug.
Thank you, Dr. Richardson. I would like to now invite to provide her perspective on these results, Dr. Crystal Proud, a well-renowned thought leader in the care and treatment of those with Duchenne muscular dystrophy. In addition to caring for children with general neurological conditions, Dr. Proud is a board-certified pediatric neuromuscular neurologist with an expertise in caring for children with Duchenne muscular dystrophy, spinal muscular atrophy, Charcot-Marie-Tooth neuropathy, other muscular dystrophies, congenital myopathies, and MS. Dr. Proud received subspecialty training at Stanford University in both child neurology and pediatric neuromuscular neurology, participating in clinical research trials for children with muscular dystrophy and SMA. Dr. Proud is currently the chief of neurology and director of neuromuscular medicine at Children's Hospital of The King's Daughters, CHKD, in Norfolk, Virginia, where she works collaboratively to provide a comprehensive approach to patients with neuromuscular diseases.
With her research focused on the development of therapeutic trials for spinal muscular atrophy and Duchenne muscular dystrophy, she is the primary investigator for several clinical trials evaluating novel treatments for patients with various neuromuscular conditions. She also serves as the medical director for the CHKD Novel Therapeutics and Gene Therapy Center, with a commitment to optimizing clinical care and offering participation in clinical research to patients and families affected by rare disease. I am honored to turn to Dr. Proud for her perspective on these results. Dr. Proud?
Thank you, Doug. Thank you for having me here today. I think that these results are incredibly encouraging, and to be honest, they're consistent with my continued expectations for this therapeutic program. They also mirror my observations personally from my treated patients within the clinical setting. The beneficial impacts of ELEVIDYS really have been very tangible and measurable, and the distinction from my untreated patients is quite clear. The results demonstrate that ELEVIDYS really is changing what was known to be the natural history for these boys with Duchenne muscular dystrophy, and treatment has led to differences in their abilities to walk, to run, to perform everyday activities that many of us can very easily take for granted.
So overall, I look forward really to the continued data updates as we can look forward to a new horizon for Duchenne, and this continues to demonstrate that we're continuing to push the envelope of expectation and hope. So I'm incredibly encouraged to see these results today.
Thank you so much for that. With that, let's open the line for Q&A.
Thank you. To ask a question, please press star one one on your telephone and wait for your name to be announced. To withdraw your question, please press star one one again. We ask you, please limit yourself to one question each. Our first question is going to come from Brian Abrahams with RBC Capital Markets. Sir, your line is open.
Hey, good morning, guys. Thanks so much for taking my question, and really nice to see the patients in the study continuing to drive benefits over the longer term here. Maybe just a question just in terms of process. I guess I'm curious if you could maybe walk us through any differences in the external control here versus in the 2-year cut. I think the press release suggests there's maybe some subtle differences, and I'm just kind of wondering if that was due to the matching to the cohort that you have now that are in this open-label extension. And then I guess I'm curious how you're going to be using some of the learnings here to really hone in on the messaging to clinicians and centers around the efficacy benefits that you're planning to focus on this year. Thanks.
Thank you very much for your two questions. I will turn the first part of the question over to Dr. Richardson. Before I do that, I'll answer the second part by just reminding everyone, and we discussed this at JP Morgan, that we have a real opportunity in front of us today to really rebalance the discussion talk, obviously, about the safety of our therapy and the proper administration and monitoring, but also balance that with all of the wealth of efficacy data we have. That is going to be a big part of our strategic goals over the course of 2026 and beyond. And to that goal, we have already—we're in the process, actually, of doubling the size of our sales force book. We're going to have much more robust and well-balanced promotional activity as well. We've got peer-to-peer discussions on that.
We'll be talking to the community to make sure the community is aware of what we're doing so that we're fully transparent with them. So we have a lot of things to do this year to discuss broadly with everyone who can benefit from it, HCPs and the community, the accurate and balanced information around this therapy. And there is no doubt, Brian, to your very good question, that this three-year data and what it means for the long-term benefits of this therapy over time is going to play a significant role in those communications. With that, I'm going to turn it over to Dr. Richardson to answer the first part of that question.
Thanks, Doug. Thank you for the question. So just to reiterate, the sources selected for external control and the methodology for years 2 and year 3 were both pre-specified. I think the disparity that you're pointing out to is simply the availability of patients in external control with 3 years of follow-up that otherwise meet the criteria for matching. So that's why we see a slightly lower number in the external control at that point. But as you can see from the baseline characteristics, they remain extremely well-matched, and I think it's still a very significantly sized comparison.
That's really helpful. Thank you.
Thank you. The next question is going to come from Andrew Tsai with Jefferies. Your line is open.
Hey, good morning. Thanks for taking my question. So given this trajectory that you're seeing, would you expect to see some kind of mortality benefit soon, especially for the older ambulatory patients, or would that take a little bit longer? I'd imagine seeing something like that could really drive real-world adoption. Thanks.
I will once again turn this over to Dr. Richardson. Thank you for the question again. So I mean, I think that looking at these disease milestones, which obviously mortality is the most significant, is something that we continue to do. It's really about the number of events that you see that will drive our ability to demonstrate a statistically significant difference. So I think that seeing that in mortality will take a number of years given the natural history of Duchenne. I think that we'll see it in other milestones like loss of ambulation sooner.
Thank you.
Thank you. Our next question will come from Yun Zhong with BTIG. Your line is open.
Hi, good morning. Thank you very much for taking the questions. It's very nice to see the positive data coming out from three years of treatment. My question is, so for those clinicians and patients that might be more concerned about safety rather than efficacy, because efficacy apparently is a very good separation from natural history studies, so will you be able to provide any additional safety data, maybe not necessarily from this study, but from additional studies in 2026 to address those patient and clinician concerns, please?
Yeah, that's a very good question. James, you want to take that?
So I mean, obviously, our safety team are constantly updating our understanding of the safety signals created both in the clinical trials and the real-world setting. That's something that is communicated, obviously, near real-time with the FDA and will be reflected on one hand in future label updates if necessary, which I don't expect at the moment. And then in terms of making them more widely available, yes, we certainly do have some publications in mind, publications in mind for 2026 that will continue to keep prescribers and the community aware of the growing body of data we have regarding the safety of this drug.
Great. Thank you.
Thank you. And our next question is going to come from Ritu Baral with TD Cowen. Your line is open.
Good morning, guys. Thanks for taking the question and the update this morning. I wanted to just focus on slide 20 and the year 3 Expedition trial SAEs. Can you give any more detail on the 4 newly emergent SAEs as detailed on slide 20? And in the footnotes, it clearly says something about excludes unresolved events that began prior to this period. Can you characterize sort of the ongoing unresolved events over the year? And then if there's any detail on the dropouts. Thank you.
Once again, Dr. Richardson.
Yes. So just to take that question, I think in the parts that I heard. So first of all, the unrelated SAEs in year three were a variety of conditions, I think, assessed both by the company and the investigator as unrelated, including, for example, an appendicitis, to give one example. The footnote around the continuing AEs or SAEs between years is mostly just an ability to be able to tabulate these data with, I think, any sense, because we will have events that cross that period between year one and year two, and we need to understand where we're going to capture that. It's not, I think, because of any very prolonged SAEs that we're seeing within these patients.
Thanks.
Thank you. And our next question will come from Yigal Nochomovitz with Citigroup. Your line is open.
Yeah. Hi. Thank you for the question. For Dr. Proud, I was just wondering if you could speak a little more to what struck you the most in the long-term data that perhaps wasn't apparent from your anecdotal experience with ELEVIDYS in your clinic.
Yeah.
Thank you for that question. So I think that my clinical experience really mimics the data that you've seen, Dr. Richardson, present here today. I've been able to observe higher North Star Ambulatory Assessment scores than what I would otherwise have expected in my untreated patients. I've been able to see my patients continue to rise from the floor in times that are quite impressive given their age at a time where I might expect for them, based on the natural history data, for us to be able to see a decline where they take longer to rise from the floor or longer to ambulate 10 meters. I'm seeing that those numbers have stayed quite low compared to what I would expect for their age. And this is really meaningful to me because this is how I provide prognosis to families and preparation for families.
Once a child hits a 10-meter walk time of 10 seconds or greater, they are expected to be in a wheelchair and non-ambulatory within the next couple of years. These are things that really help to facilitate my conversations with families as they navigate this disease. We're changing expectations now based on these results. So I'm incredibly pleased to be having a different dialogue these days with those families.
Thank you. Just one quick one for the company. When you look at this data, I'm just curious if you did any sensitivity work around the conclusions if you were simply to look at just the natural history components of the synthetic control or just say the RCT component, if things generally look the same that way? Thanks.
James.
Sorry, I'm not fully understanding that question. Could you repeat it, please?
Well, I believe you had an RCT component in the control and then two natural history controls. I'm just wondering if you were to run the analysis, say, with just the natural history controls, would that still support the conclusions or?
Understood. Understood. Yeah. We haven't done that analysis as of yet, but it's a good thought. I don't imagine it would make a difference, but we can certainly look at that.
Great. Okay. Thank you very much.
Thank you. Our next question will come from Kostas Biliouris with BMO Capital Markets. Your line's open.
Thanks for taking my question and congratulations on the data. One question for Dr. Proud and one for management, please. Maybe for Dr. Proud, to what extent do the unfortunate deaths in non-ambulatory patients last year impact your decision to treat ambulatory patients with ELEVIDYS currently, especially given these three-year efficacy data? For management, now that you have two-year data post-dosing for all patients from the two groups, have you looked into how the NSAA trajectory compares between the two groups from year one to year two post-dosing? You had shown this last year. I don't know if you have done this analysis this year again. Thank you.
Yeah. So I'll have James touch on the second of the two questions, and then we'll turn to Dr. Proud for her thoughts.
I'm sorry. Could you repeat that question?
I think the question that Costas had is basically, we had shown 2-year data for the part 1. We'll have 2 year data for the part two. Have we done an analysis or a pooled analysis of those 2 to see what that might look like?
Yeah. Sorry. Thank you. Yeah, yeah, absolutely. So we have done a pooled analysis looking at all patients dosed over up to a 2-year period. The Part 2 patients are obviously dosed a year older and assessed a year older. So it's a slightly different analysis set to what you might want to compare with just the Part 1 patients dosed on their own. Nonetheless, the results are highly concordant.
And then Dr. Proud?
Yeah. So my conversations with families these days involve discussion around the updated prescribing information and making sure that my patients and families are aware of all of the potential benefits and the possible risks that go along with this therapy, just like any other therapy that I might prescribe. Of course, I'm optimistic as we are able to consider the future clinical trial landscape and the knowledge that we might gain from expanding the opportunity to older and non-ambulatory patients by looking at the Cohort 8 data set that will eventually be generated through addition of sirolimus in hopes that this may reduce some of that risk that we had been noticing regarding liver events in the previous cohorts. So as we generate more data, that will then inform that continued dialogue that I have with my families.
But those safety events do not necessarily augment my capacity to be able to offer this to families.
Thank you so much.
Thank you. Our next question will come from Salveen Richter with Goldman Sachs. Your line is open.
Good morning. Thanks for taking my question. In the context of the data that you're seeing to date, maybe help us understand how long you think a patient should be treated on this drug.
I'm not. Apologies for that. I'm not sure. This is a one-time therapy, right? So.
Yes, but the duration of benefit that you're seeing in patients is usually at three, drug-arm versus control-arm, year-over-year.
Oh, apologies. Yeah, yeah. Apologies for that. I mean, James, do you have any thoughts on that? I mean, I will say, generally speaking, obviously, we have not seen any diminution of effect either preclinically in our animals over a long period of time. And of course, now we have a very small group of patients all the way up to published five-year data. And then, of course, now we have in these patients a widening divergence of benefit versus external control as you're tracking. The long-term benefits we'll only know together over the next, hopefully, 10-20 years. But Dr. Richardson, do you have any additional thoughts on this?
No, I think that captures it, Doug. I mean, as you said, we don't see any diminution of effect yet. We're clearly impacting the natural history over these three years that we're presenting, and we'll continue to understand more about this as the data evolves.
Yeah. And I'll just say one more time. And of course, if we really want to look over the very long term, the only thing we can do is look to some of our preclinical data. And again, we have seen continuing benefits from this therapy for as long as we've been able to look, which the last time I think I was updated was somewhere in the 9-year range. So very good long-term benefits from this therapy.
As we can see, both in a pilot study, what was called 101, small group of patients, and now with a well-controlled clinical trial, pre-specified results, we're seeing not only a maintenance of benefit, but a significant divergence of benefit versus external control, which is exactly what one would anticipate from a disease-modifying therapy like ELEVIDYS, which works by providing to patients a functional form of the very dystrophin that protects their muscles that they are missing, which is the sole cause of this disease.
Thank you. Our next question will come from Uy Ear with Mizuho. Your line is open.
Yeah. Thanks, guys, for taking our questions. So maybe one question for management and one question for Dr. Proud. For management, what do you expect to do with the data with respect to the label? Are you going to the FDA and try to get this data and serve it into the label? And for Dr. Proud, you mentioned sirolimus use, and we're just wondering, based on your conversations with your colleague, how prevalent or do you see a trend moving into larger sirolimus use? Thanks.
Yeah. I will touch on the management question very briefly to tell you that these top-line results are hot off the press. And so we haven't made any decisions, for instance, about whether one would benefit from an updated label. Of course, these results are very consistent with the labeled indication that we have, which, as you know, is a traditional approval for all ambulatory patients four years and above. So they will play a significant role in our future communications about the benefits and risks of this therapy, whether we choose to make a label update based on something that we have to assess later to decide if it was necessary or helpful. And with that, I'll turn the second question on the use of sirolimus to Dr. Proud.
Yeah. Thank you for that question. It's an interesting one. I think that we have a lot to learn about the potential benefit of adding sirolimus to our treatment paradigm. And of course, we'd like to try to mitigate risk as best we can. And so I think that what we'll have to do is really look towards the data to be able to inform us most comprehensively. Once we can analyze the impact of sirolimus addition to therapeutic protocols, then we can truly understand the benefit and whether or not this is something that we need to be incorporating into our clinical practice in the future.
Thank you.
Thanks, Crystal. I just wanted, if I could, to offer a little bit more color going back on a question that I think that I missed around the patients who had adverse events between year two and three and patients who dropped out between year two and three. So I think, first of all, just to clarify that the one serious adverse event in year two has resolved, so that patient is not still suffering an ongoing serious adverse event in year three. As regards to the patients who dropped out, this was largely for personal reasons. And as said during the presentation, the impact of this has been looked at fairly rigorously with a number of different ways, particularly looking at their performance in years one to two. And their functional performance was very much in keeping with the other patients that continued on into year three.
If you conduct an analysis of all the patients, so a full analysis set is what we presented to you today, and compare that to a complete analysis set, the patients who have data in year one, year two, and year three, we see no real discordance, which is not what you would expect if these dropouts were impacting results overall. Apologies for missing that question first up, and hopefully, that satisfies.
Thank you. And the next question will come from Kristen Kluska with Cantor Fitzgerald. Your line is open.
Good morning. Thanks for taking my question. As you think about patients, physicians, or caregivers that have been more hesitant about ELEVIDYS use, how much of this was ultimately driven by questions still around efficacy? And now that you have these data on hand, do you think that you could sway some that were on the fence prior?
I'm just going to answer that in the broadest senses, which is I think there is, I think, given some of the challenges of 2025 and the obvious requirement that we spend a lot of our time talking through the safety and the like, I think there's a real need in the community and in the patient community and the physician community to fully understand this therapy with respect both to safety and to the benefits of this therapy. And so I do think there's a real value that will come from additional education around this.
We have plans throughout the course of this year and into next year to really educate physicians and patients and their families on the benefits of this therapy, all of the prior study results that we've seen and what we're seeing out there, as well as the results of this year three from our pivotal trial in EMBARK, and to talk to them as well about not only the safety of the therapy, but also the administration of the therapy, updated practice. Our label, as you know, we updated it late last year. It includes additional monitoring to support safety. It includes advice on more proactive reaction if there are labs that are different. So we'll educate on all of these things.
There is no doubt that having an opportunity to really talk to families and physicians about the objective benefits of this therapy from our clinical trials is going to be meaningful to them. There's a lot of educational opportunity in all of this.
Thank you. The next question will come from Biren Amin with Piper Sandler. Your line's open.
Yeah. Hi, guys. Thanks for sharing the data update. Maybe just a question on for the three-year, did you measure left ventricular ejection fraction at year three? And can you share details around stabilization and improvement of that endpoint? And also, was there any evaluation done on respiratory function, like forced vital capacity? Thanks.
Sure. Dr. Richardson .
So cardiac function was measured both with echocardiography and with cardiac MRI in a subgroup. We haven't analyzed that data yet, but we'll be doing so in the coming weeks, and we'll be making that public when we have the opportunity. As regards to respiratory function, due to the age of these patients, respiratory function wasn't measured in the EMBARK study. We are measuring it in EXPEDITION. So we will have data on these patients as they stay in the study over years, but there is nothing meaningful to share at this time, given it's just happening in the EXPEDITION study.
Thank you. And the next question will come from Sami Corwin with William Blair. Your line's open.
Hi there. Thanks for taking my question. I was curious if you've seen any correlation on the individual level between microdystrophin expression or other biomarkers earlier on in this long-term functional benefit. And then I was also curious if you've seen any functional cardiac benefit over this longer duration of follow-up. Thank you.
Dr. Richardson.
So I think that the association between dystrophin expression and function is more clearly seen as we have more patients over a larger period of time, but it's, I think, a complex relationship and a non-linear one. In terms of cardiac function, I just refer back to my previous answer. So I think that, I mean, I think, first of all, these patients are still relatively young to see a lot of cardiac decline, even in the natural history. But we are certainly interested in continuing to follow these patients to both ensure that they're stable from a cardiac perspective and that over time, as a natural history, would predict a decline in cardiac function with seeing a treatment benefit with ELEVIDYS. But those data for year three are still pending analysis, and I think will become more interesting as well in subsequent years.
Great. Thank you.
Thank you. The next question will come from Mitchell Kapoor with H.C. Wainwright & Co. Your line's open.
Hi. Good morning. This is Katie on for Mitchell. Looking at your data, it's mostly presented as means. And I guess my question is around the variability within that data set. Are there outliers on either end of that response? And have you considered presenting that data in terms of milestones in the future, something like TTR greater than five seconds?
Sure. Dr. Richardson.
The individual pattern of response is, in general, one of stabilization of their disease path, as we would expect from a dystrophin-restoring therapy and a reduction in the frequency of patients with rapid decline. In terms of milestone analysis, yes, absolutely. We're super interested in milestone analyses. I think that in terms of loss of functions, whether that's a timed function test or loss of ambulation, the absolute numbers losing those functions in the external controls are still relatively low, which is inhibiting our ability to produce analysis right now. But we are continuing to look at the data, and I'm confident that we'll be able to show an effect on important clinical milestones in the future.
Thank you.
Thank you. The next question will come from David Hoang with Deutsche Bank. Your line is open.
Hi. Good morning. This is Sean for David. I just have one question that I have is around the ambulatory status. So can you comment on the ambulatory status of patients, if there was any patient during the three-year window who transitioned from ambulatory to non-ambulatory? And my second question is more broad. So how do you think this three-year data set could impact prescribing patterns and commercial uptake as we progress through 2026?
Yeah. Answering the second question, of course, it's all about education so that both the patient community and the caregiver and the physician community, both treating physicians and referring physicians, have a balanced understanding of the profile of this therapy, including the benefits, not only the immediate benefits of the therapy when watching it over a short 12-month period, but seeing the diverging benefits in trajectory when you have a disease-modifying therapy that's changing the future for these patients. So that will all come down to education. And we certainly are strong believers that education works insofar as it allows for an informed group to consider therapeutic options. So we'll more to come on that. And as relates to the first question, I will turn it over to Dr. Richardson today.
Thanks, Doug. So I think this also relates to the last question about milestone analysis. So we had 2 patients in the treated arm who lost ambulation over that 3 years, which is roughly about half the number that lost ambulation in the external control. We see a similar signal on other milestones. As I said, the absolute numbers are relatively small now to be able to come out with a formal analysis.
Thank you. The next question will come from Gil Blum with Needham & Company. Your line is open.
Good morning, everyone. Thanks for the comprehensive update. Maybe this is just one question as it relates to the NSAA change in the treatment arm from year two to year three. So it does appear that there's a certain level of decline, obviously, not nearly as much as seen in the external control. Can you put the decline in context? Is this within error margins, or how should we view this? Thank you.
Sure. Again, Dr. Richardson.
Excellent question. So I think, again, what we're seeing is largely a stabilization of the treatment trajectory of patients. And so we do see patients who are declining post-treatment. But if you look at the individual trajectories, those are overall declining less steeply if they're declining than the external controls. So I think that to see no decline in the NSAA in treated patient s is not a realistic treatment expectation, but I think to see a greatly modified disease trajectory is a realistic expectation.
Thank you. The next question will come from Anupam Rama with JP Morgan. Your line's open.
Hi, guys. This is Priyanka on for Anupam. Thanks for the update. It might be too early to tell, but are there noticeable differences in treatment effect in those who are treated at a really young age, like four years, versus the relatively older population of seven years? Thanks.
Dr. Richardson, do you have that information?
We haven't completed an analysis of these by age yet, but historically, we have seen, across our data sets, good treatment effect both in younger patients and patients closer to an older age. There tends to be different sensitivities depending on the timed function test or whether we're looking at the NSAA, which is related to how sensitive those particular tests are to the age group and when that age group expects to lose that particular function.
And just to remind everyone that Dr. Richardson is speaking to the functional test manifestations. But remember, while the average boy is diagnosed somewhere in the 4, 4.5-year range, this disease is causing damage even in utero. So even by the time a boy is born, they're beginning the process of damaging their muscles. And remember also that a therapy like ELEVIDYS and any other therapy that is possible today with respect to Duchenne muscular dystrophy, you cannot bring muscle back that has been damaged. It can only slow or stop future damage. I mean, I'm talking even broadly about other therapies as well. So the concept of early intervention, just Occam's razor tells us that it is going to be beneficial to get to patients as soon as reasonably possible to stop the damage that could occur from disease.
Thank you. As a reminder to ask a question, please press star one one on your telephone. Our next question comes from Yanan Zhu with Wells Fargo. Your line's open.
Oh, great. Thanks for the update. Maybe a quick question for the company and a question for the doctor. Is there any planned muscle biopsy in year three and also in future, if not, perhaps anything planned in future years? For the doctor, I was wondering, could Dr. Proud comment on patient interest for ELEVIDYS in the ambulatory population at your practice, and how has it evolved since the initial safety update in early 2025? Do you think it could recover to pre-safety update level with enhanced education and promotion? Thank you.
Sure. Let's turn first to Dr. Proud, and then we'll turn back to answering the first part of your question.
Sure. So interest from my patients in clinic, I have not seen a shift as far as any sort of decline in interest. I think that my patients know, based on the dialogue that I have with them routinely, that my primary objective for them is to pursue a dystrophin-restoring therapy as the foundation for their treatment. And so as ELEVIDYS is a dystrophin-restoring therapy, that would be something that we would have dialogue about. So I've not necessarily seen any change over time or decrease in that level of interest. I think that data like the data that has been shared today is certainly something that they will be eager to discuss with me as they make decisions on their treatment moving forward.
And then, Dr. Richardson, can you just confirm my understanding that there wouldn't be biopsies associated with these year three patients? Is that correct?
That's correct. There's no biopsies in the pivotal extension protocol.
Yeah. I mean, just so we understand, there's a lot of reasons why it would be very difficult. First, it is unbelievably intrusive to do a biopsy. It is one of the most difficult parts of a clinical trial for these families. So limiting the number of biopsies to those that are absolutely required is an important overarching goal. And second of all, one of the issues we have with the long-term follow-up on this study and studies like it is this is a one-time therapy. So these families that are participating and staying in the study for multiple years are really doing an enormous service to other families since they've fully received the benefits of their therapy. If one burdens them with additional biopsies, it would very likely cause either reluctance to enter studies like this or, frankly, higher dropout rates than would be acceptable.
I think it would be very difficult to do that.
Great. Thank you for the comment.
Yeah. Do you disagree with me on any of that, Dr. Richardson? Oh, sorry, Louise. Apologies. I interrupted you.
Yeah. No, I just wanted to remind that we did do multiple time points of biopsies previously in EMBARK. The one-year results for the later time points were actually consistent to somewhat higher in terms of expression over time. We've looked in series at multiple time points previously and saw consistency and actually some growth over time.
Great. Thanks for the comment.
Thank you. And the next question will come from Andy Chen with Wolfe Research. Your line is open.
Hey, this is Brandon on for Andy, and thanks for taking the question. The work that you've done, we're curious to know, are you able to quantify the group amid the DMD community that leads with a hesitancy to take the therapy because of more of a safety concern, or is it broadly the skepticism around how efficacious the drug could actually be?
Well, I think generally speaking, I think we would say, and I'll turn this to Patrick if he has any additional direct objective market research on this. But broadly speaking, it really is an information deficit issue. We just need to provide fully balanced information on the benefits and the safety profile of this therapy. But Patrick, you can provide any additional color that you have on that.
Yeah. I mean, you've hit the nail on the head. This data, it's extremely important, and we're going to factor all of this into our conversations both with physicians as well as patients and families. Just a reminder, this is the first time we've had this type of data for a gene therapy. So we are going to lean in and balance our discussion as we talk about both safety and efficacy.
Thank you. I am showing no further questions in the queue at this time. I would now like to turn the conference back over to Doug Ingram for closing remarks.
Thank you for that. Let me just say thank you to a few folks. Before we conclude, I want to thank once again, Echo, Dr. Richardson, and Dr. Rodino-Klapac. Thank you to both the families that participated in this study, as well as our investigators who have committed themselves to these patients and played a significant role in these studies. I want to thank specifically Dr. Crystal Proud for her willingness to take time out of her very, very busy schedule to provide her valuable perspective and insight on the meaningfulness of these results. I want to thank all of you for joining us today and for your very thoughtful questions.
We really appreciate that and look forward over the course of this year to providing additional updates on all of the work that we're going to be doing, including, as we've talked about today, our various education plans to talk about not only these results, but the broader issue of the benefits of this therapy and the entire profile of this therapy ELEVIDYS. We also, as you will remember, have some really interesting results from the rest of our pipeline, including our siRNA therapies, both DM1 and FSHD, which will happen right around the very late first quarter of this year. So looking forward to updating you across the year as we continue to serve the communities that we serve and execute on our plans. With that, have a wonderful day, everybody.
This concludes today's conference call. Thank you for participating, and you may now disconnect.