Good morning, and welcome to the Wave Life Sciences 48 FORWARD-53 Data Update conference call. At this time, all participants are in a listen-only mode. As a reminder, this call is being recorded and webcast. I'll now turn the call over to Kate Rausch, Vice President of Investor Relations and Corporate Affairs. Please go ahead.
Thank you, Operator. This morning, we issued a press release announcing positive 48-week results from our FORWARD-53 clinical trial of WVE-N531 for the treatment of exon 53 amenable Duchenne muscular dystrophy. A press release and the presentation to accompany this call will be found in the Investor Relations section of the website, www.wavelifesciences.com. Before we begin, I'd like to remind you that discussions during this conference call will include forward-looking statements. These statements are subject to a number of risks and uncertainties that could cause our actual results to differ materially from those described in these forward-looking statements. The factors that could cause actual results to differ are discussed in the press release issued today and in our SEC filings, including our annual report on Form 10-K for the year ended December 31, 2024.
We undertake no obligation to update or revise any forward-looking statements for any reason. Today, Dr. Paul Bolno, President and Chief Executive Officer, will begin with opening remarks on the opportunity for WVE-N531. Next, Dr. Erik Ingelsson, Chief Scientific Officer, will present the FORWARD-53 clinical results. Paul will conclude the prepared remarks with next steps and anticipated milestones before turning it over to Q&A. Dr. Chandra Vargeese, Chief Technology Officer, will also be available to answer questions. I'd now like to turn the call to Paul.
Thanks, Kate. Good morning and thank you for joining us today. Wave was founded on the commitment to unlock the broad potential of RNA medicines to transform human health. Over a decade ago, we recognized the opportunity to leverage our innovations in chemistry and oligonucleotide design to provide new therapeutic options for Duchenne muscular dystrophy. We drew inspiration from the incredible resilience of the DMD community, including those that have participated in our clinical studies over the years, as we began advancing our WVE-N531 program in hopes of serving the vast unmet need in this devastating disease. DMD is one of the most severe forms of inherited muscular dystrophies. It's caused by mutations in the dystrophin genes that result in a lack of dystrophin protein and subsequently progressive muscle degeneration.
DMD impacts individuals early in life, with boys missing key motor milestones as early as age two or three. As the disease progresses, individuals living with DMD typically develop respiratory, orthopedic, and cardiac complications. Ultimately, the disease is fatal due to the irreversible loss of muscle function in the heart and diaphragm. There is an urgent unmet need for new, safe, and effective therapies. Each year, there are approximately 20,000 new cases of DMD, with up to 10% amenable to exon 53 skipping. With N531, we're utilizing an exon skipping approach aimed at restoring the reading frame of the dystrophin transcript to produce a functional dystrophin protein, such as those seen in Becker muscular dystrophy patients who have a milder disease course.
Within Becker, those that have levels of dystrophin of 5% or greater have later loss of ambulation and better functional outcomes, supporting the therapeutic relevance of this level. To be effective, a therapy must distribute broadly, including to the heart and diaphragm, as well as reach muscle stem cells and ultimately preserve and restore muscle function. N531 was designed with our best-in-class oligonucleotide platform, including PN chemistry, which enables differentiated muscle delivery, access to both myogenic stem cells and muscle fibers, and long half-lives for extended dosing intervals, all without the use of muscle delivery conjugates. In preclinical studies, we saw significantly greater concentrations and dystrophin expression in the heart and diaphragm, coupled with functional and survival benefits. Today's update is from the 48-week assessment in FORWARD-53, our open-label phase II study, which looked at safety, dystrophin expression, longitudinal muscle health, and functional outcomes.
Our N531 program began with part A, where after dose escalation, three boys received 10 milligrams per kilogram doses of N531 every other week. In this initial portion, we achieved differentiation in N531's profile, with industry-leading exon skipping of 53% and muscle tissue concentrations of 42,000 nanograms per gram, substantially higher than any muscle delivery conjugate program. We also saw initial evidence of uptake in muscle stem cells. N531 was also safe and well tolerated. In part B, we evaluated N531 every other week in 11 boys, with a novel design to take muscle biopsies following 24 and 48 weeks of treatment to evaluate the impact on longitudinal muscle health. In our planned 24-week interim analysis, we saw exon skipping and muscle tissue concentrations were consistent with part A results, suggesting they stabilized after three doses.
We also observed mean muscle content of the dystrophin expression of 9%, as well as a safe and well-tolerated profile. Tissue half-life was 61 days, which is supportive of a monthly dosing regimen. We also observed an improvement on key serum biomarkers, including creatine kinase, and compelling initial evidence of myofiber regeneration resulting from sustained high levels of dystrophin and our unique access to the myogenic stem cells. We're not aware of any other clinical data for exon skippers or gene therapy that have been able to demonstrate myogenic stem cell uptake in the clinic, as shown on the right of slide 11. These stem cells are the progenitor cells that produce new myoblasts and are essential for the regeneration of muscle. In DMD, the absence of dystrophin in muscle stem cells impairs both cell division and myogenesis by diminishing the self-renewal capacity of these important cells.
Thus, restoring dystrophin in muscle stem cells is expected to both preserve the renewal capacity of muscle and initiate productive repair of muscle fibers. It was exciting to see this begin to occur at 24 weeks. Following 48 weeks of treatment, our goal was to demonstrate these achievements translate to improvements in muscle health and functional outcomes, which we did. We're excited to share our 48-week results, which are unprecedented and strongly support N531 as a best-in-class treatment for boys amenable to exon 53 skipping. This includes the largest effect on Time-to-Rise at 48 weeks relative to any approved dystrophin restoration therapy. The Time-to-Rise results are statistically significant, reinforcing how substantial the effect size was in this study.
With an ability to evaluate muscle now at multiple time points, we saw substantial improvements in muscle health, as evidenced by a statistically significant reduction in fibrosis and CK, driven by decreases in inflammation and necrosis. For a dystrophin restoration therapeutic, this is the first time that a significant reversal in muscle fibrosis has been observed. In addition, we observed sustained and industry-leading muscle tissue concentrations, exon skipping, and dystrophin restoration with highly consistent dystrophin protein levels across boys and over time. WVE-N531 was safe and well tolerated with no serious adverse events or discontinuations. I'll now turn the call over to our Chief Scientific Officer, Dr. Erik Ingelsson, to review the detailed 48-week results.
Thanks, Paul. As Paul already outlined, FORWARD-53 is an open-label phase II study designed to evaluate safety, dystrophin expression over time, longitudinal muscle health, and functional outcomes. We enrolled 11 boys ranging from 5 to 11 years of age at baseline, all were on stable steroid regimens, 10 were ambulatory, and 1 non-ambulatory. Through 48 weeks of treatment, WVE-N531 continues to be safe and well tolerated. All drug-related events were mild to moderate in intensity. There were no serious adverse events and no study discontinuations. One participant experienced a non-drug-related severe treatment-emergent adverse event, which was a short-lived episode of gastroenteritis that resolved on its own. This is a favorable safety profile for next-generation exon skipping therapy, which we believe will be important for the DMD community and prescribers alike.
As a reminder, in FORWARD-53, we collected biopsies at two time points, after 24 weeks and after 48 weeks of treatment with WVE-N531. Two biopsies in the same boy during treatment is a unique aspect of FORWARD-53, as it for the first time ever enabled studies of dynamic changes to dystrophin levels and muscle pathology in boys under disease-modifying therapy for DMD. For these analyses, we focused on the eight ambulatory boys that had muscle biopsies available from both time points. exon skipping was highly consistent, averaging 54% between week 24 and 48. Similarly, we observed sustained and consistent production of functional dystrophin, both across study participants and over time. At the interim readout at week 24, we reported dystrophin of 9.0%, and now at week 48, we observed mean dystrophin of 6.4%.
The difference between these two measurements is within the established 30%-35% interactive variability of Western blotting. Being fully aware of the limitations of this method, especially in the context of longitudinal studies of muscle health, we ran an orthogonal dystrophin immunoassay. Where all paired samples from week 24 and week 48 were put on the same blot to minimize batch effects. As seen in the middle figure, the dystrophin levels from the two time points were highly consistent when analyzed together. This strongly supports that dystrophin levels stabilized at a therapeutically relevant level already after 24 weeks of treatment with WVE-N531 and emphasizes the strength of having two on-treatment measures in FORWARD-53, which allows us to calculate dystrophin levels over time with greater precision by averaging two measurements. Therefore, we're reporting the average dystrophin levels between week 24 and 48.
The mean dystrophin was 7.8%, with a 95% confidence interval of 5.4%-10.3%. On the right, you'll see that dystrophin levels were very consistent across participants, with 7 out of 8 or 88% achieving average dystrophin of greater than 5%. Overall, these data highlight our differentiated profile suggesting muscle regeneration and improved muscle health. I'll now share how the profile of N531 is translating to improvements in muscle health. As a reminder, in healthy individuals, muscles are built to repair themselves when they undergo damage. In DMD, muscle is very fragile, and damage accumulates because of the lack of dystrophin. This results in the inability to productively differentiate activated stem cells to mature muscle cells. As a result, chronic inflammation and tissue necrosis is induced, leading to increased muscle loss and fibrosis.
This regenerative process is constantly turned on, leading to lack of fiber maturation and ultimately replacement of muscle fibers with fibrotic and fatty tissue. Leveraging the unique features of N531 with delivery to both stem cells and muscle fibers, and induction of industry-leading exon skipping and dystrophin production, we expected to see changes to pathology reflecting healthier muscle. That is exactly what we saw, as I'll go over in the next few slides. Turning to slide 19, you can see muscle biopsies taken after 24 weeks of treatment with N531 on the left and after 48 weeks on the right. Across seven paired biopsies available for histopathology, we see a consistent improvement in the organization and uniformity of myofibers in muscle tissue. The purple dots represent the mixture of inflammatory cells and regenerating cells. In short, the fewer purple dots, the healthier it is.
We also looked at these muscle biopsies using semi-quantitative assessments. To evaluate inflammation and necrosis, muscle sections from biopsies at 24 and 48 weeks were evaluated using a severity scoring system, with higher numbers indicating more severe pathology. After 48 weeks of treatment, median scores shifted towards less severe inflammation, as shown on the left, and less severe necrosis, as shown on the right, when compared with samples evaluated at 24 weeks. In healthy muscle, acute inflammation promotes healthy muscle repair. Macrophages infiltrate muscle tissue and respond to damage and initiate a pro-inflammatory cascade. In DMD, the ability to limit these inflammatory signals is compromised, contributing to pathology. MCP-1 and IL-6 are both inflammatory cytokines in this cascade, and both were meaningfully lower after 48 weeks of treatment compared to baseline. These data suggest a lower level of systemic inflammation in response to N531 treatment.
Creatine kinase or CK is released from muscle fibers in response to damage, and serum CK levels are elevated in DMD, making it an important biomarker of muscle injury. In FORWARD-53, serum CK levels dropped rapidly with treatment onset and have plateaued at levels 50% lower than baseline, which matches levels consistent with a milder DMD phenotype. CK levels in boys on N531 were significantly lower than the matched C-Path natural history cohort. These significantly lower CK levels in combination with improved muscle architecture indicate a notable and unprecedented improvement in muscle health. During muscle regeneration, Pax7 in stem cells and internalized nuclei in myofibers mark different stages along the regeneration pathway. We quantified these features to evaluate the regenerative state of the tissue. Recall that at 24 weeks, we observed early signals that we had initiated regeneration of myofibers.
Now, at 48 weeks, we see a 20% decrease in the density of Pax7- positive stem cells, suggesting a shift past regeneration towards muscle maturation. We also see a decrease in the percentage of cells that exhibit internalized nuclei, which is a hallmark of late-stage myotubes. This decrease, as well as the profoundly improved appearance of the tissue sections, is also consistent with a shift from muscle fiber regeneration to maturation. Using a stain for fibrotic tissue, we were able to quantify fibrosis in biopsies after 24 and 48 weeks of treatment. As seen on the left, the percentage of fibrotic tissue in biopsies declined significantly between 24 and 48 weeks. Visualization of this profound change is illustrated by two representative boys on the right, where the red color indicates fibrotic tissue. In addition to the decrease of fibrotic tissue, the improved tissue organization at 48 weeks is readily apparent.
We're not aware of any exon skipping therapies that have demonstrated decreased muscle fibrosis. As you will have seen in the last few slides, muscle biopsies from the boys in FORWARD-53 indicate a considerable change in muscle health after 48 weeks of treatment with WVE-N531. If their DMD was progressing, we would see increased chronic inflammation and necrosis, high tissue regeneration without muscle maturation, and increased fibrosis. Remarkably, a very different picture is unfolding. After seeing evidence of increased stem cell activation and myofiber rejuvenation after 24 weeks of treatment, we're now moving past the regenerative stage to muscle maturation at week 48, as shown by decreases in stem cell density and fewer muscle fibers with internalized nuclei, suggesting engagement of a healthy feedback loop to preserve stem cells. Necrosis, inflammation, and fibrosis are all declining, as shown by both muscle pathology and circulating biomarkers.
This suggests a fundamental shift from dystrophic towards healthy muscle, where N531 is driving newly generated muscle fibers towards maturity. All of these changes are expected to lead to healthier muscle and improved function among boys treated with N531. For functional outcomes, we compared the FORWARD-53 cohort to a genetically matched exon 53 skipping amenable natural history cohort. Baseline characteristics between these cohorts were well matched in age and Time-to-Rise, or TTR, is an early sensitive functional measure, which is becoming increasingly recognized by regulators. It evaluates how long it takes for boys to rise from the floor, with shorter rise times indicating better function. Boys on N531 performed significantly better than natural history, and the 3.8-second mean difference was substantially higher than the minimal clinically important difference, or MCID, of 1.4 seconds, based on the baseline functional characteristics of boys in the study.
I'll also remind you that this statistically significant magnitude effect, almost 4 seconds at 48 weeks, is the largest observed for any dystrophin restoration therapy at this point, higher than what had been reported for gene therapies or other exon skippers. These marked improvements reinforce that the impact on muscle health that we observed is translating to functional benefits. In addition to TTR, we measured the North Star Ambulatory Assessment, or NSAA. NSAA is a 17-item composite rating scale, where higher numbers indicate better ambulatory function. Boys receiving N531 fared favorably relative to the PRO-DMD natural history cohort on NSAA, with 1.2 points higher mean score after 48 weeks of treatment. It should be noted that typically it takes longer to see a statistically significant change from composite scores than timed function tests like TTR, so we would expect the magnitude effect to become more pronounced with longer treatment.
Beyond NSAA and TTR, we also observed positive trends in handheld myometry, which was used to assess grip strength in the left and right hands. In FORWARD-53, grip strength improved in both hands by 48 weeks. While we are excited about the clinical results following 48 weeks of treatment with N531, we're constantly motivated by the very encouraging feedback we have been getting from investigators about the progress made by boys in the trial. On this slide are just a few comments we have received from investigators, highlighting the improved mobility, functional capabilities, and quality of life that the boys in our trial have experienced. These boys are an inspiration to all of us at Wave, and we're humbled and honored to be making a positive impact in their lives. I'll now turn the call back to Paul.
Thanks, Erik. Turning to the next steps for N531 and our exon skipping franchise. The FORWARD-53 trial remains ongoing, and all participants have progressed to monthly dosing in the extension portion of the study. To augment our monthly data and ensure a monthly regimen at launch, we're also expanding to include additional boys who will be dosed monthly. Following a positive and productive meeting with the FDA on our 24-week data and initial plans for our confirmatory trial, the FDA has confirmed to us that the accelerated approval pathway with dystrophin expression as a surrogate endpoint remains open. We are aligned with the agency on next steps for N531, and we intend to submit an NDA in 2026 for accelerated approval. In the interim, we'll continue to engage the agency with our new 48-week data, including functional outcomes and our planned global confirmatory trial.
Beyond N531, we are working diligently to advance our exon skipping franchise, which also uses our best-in-class chemistry. We anticipate filing CTAs for multiple candidates in 2026. With N531, we believe we have developed a transformational approach for boys with DMD amenable to exon skipping. For exon 53 amenable DMD, there are two marketed exon skipping therapies that are dosed weekly and carry labels of limited or inconsistent dystrophin restoration. Beyond this, VYONDYS 53 generates less than 1% dystrophin at 48 weeks, while AMONDYS 45, or golodirsen, has few patients achieving over 5% dystrophin at 24 weeks. Neither therapy has shown access to the regenerative muscle stem cells. In contrast, N531 had 88% of patients achieving average dystrophin of 5% over 24 and 48 weeks, while productively delivering to the myogenic stem cells and myofibers, where dystrophin is most important.
No other therapy has shown preclinical evidence supporting effective access to heart and diaphragm, as we've shown with N531. Most importantly, N531 has uniquely demonstrated a significant shift in muscle health, resulting in a statistically significant and clinically meaningful change in function, coupled with a strong safety profile. With monthly dosing in the label, we will significantly improve on the treatment burden from the current weekly administration. Despite the limitations of currently marketed therapies, sales of exon skipping therapies were about $1.1 billion in 2024, and the broader opportunity in DMD is substantial, representing a combined $2.4 billion opportunity for exons 53, 51, 45, 44, and 52 in the U.S. alone. Currently, up to half of the exons 53, 51, and 45 patients remain untreated with exon skipping therapy.
In our conversations with KOLs, this dynamic is in part due to the burden of weekly dosing and limited evidence of benefit. Starting with N531, there are multiple opportunities to drive growth, including with expanding the number of patients using exon skipping therapies. We also expect to drive switches from existing PMOs and ultimately see opportunities for ex-U.S. expansion, where limited treatment options are available today. With the advancement of N531 and our exon skipping pipeline, Wave is now on a path to transition to a commercial-stage company. Today's results accelerate the already strong momentum of our best-in-class pipeline and the strength and differentiation of our platform, which continues to translate in the clinic.
In just the past six months, we've delivered on the first-ever RNA editing in humans with WVE-006 for alpha-1 antitrypsin deficiency, which has the potential to be a first-in best-in-class therapy for patients that currently have limited treatment options. We're on track to deliver multi-dose data from our 200 mg cohort, as well as single-dose data from our 400 mg cohort this year. Data will demonstrate the treatment profile of this therapeutic. In obesity, we've rapidly advanced our inhibin GalNAc-siRNA into the clinic at the start of the year, and our INLIGHT clinical trial is off to an excellent start with the first cohort fully enrolled. This therapy has strong support from human genetics, a unique mechanism of action, and potential to be a transformative therapy for the 1 billion people living with obesity globally.
We expect initial data in the second half of this year, including safety, tolerability, and biomarkers reflective of healthy weight loss. Before turning the call over to questions, I would like to take a moment to thank all the boys participating in our FORWARD-53 study, their families, the clinicians involved, and the study site staff. These boys inspire the work we do every day, and from everyone at Wave, we'd like to express our sincerest gratitude. With that, I will turn it over to the operator for Q&A. Operator.
Thank you. At this time, if you would like to ask a question, please click on the raise hand button, which can be found on the black bar at the bottom of your screen.
When it is your turn, you will receive a message on your screen from the host allowing you to talk, and then you will hear your name called. Please accept, unmute your audio, and ask your question. We will wait one moment to allow the queue to form. Thank you. Our first question will come from Joon Lee at Truist Securities. Please unmute your line and ask your question.
Hey, can you guys hear me?
Yes, we can.
Great. Congrats on the impressive data, and thanks for taking our questions. The myogenic stem cell uptake of 531 is impressive. How much do you think that contributed to your clinical improvements, which looks numerically superior to other exon 53 skippers? How confident are you that your Alpha-1 antitrypsin oligos for other exons can also enter the muscle stem cells and demonstrate similar magnitude of efficacy?
I'd be remiss if I didn't ask, but can you elaborate on the dystrophin level at week 48 that is numerically lower than what you've shown at week 24, despite stable exon skipping? Thank you.
Yeah, I'll take the first question quickly, and then I think move to the second, because I think the first one we can answer, which is not that it's going down as much as it's stabilizing. Erik, I don't know.
Yeah, Joon, thanks for the question. As we spoke about already at the call, although the point estimates look different, they are within the interactive variability of a Western blot of 30%-35%. As far as we know, it could have been that the 9 was a little bit higher, and the 6.5 was a little bit lower than the real number.
That is why we did that orthogonal approach, where we put samples from 24 and 48 next to each other on a blot, so we were able to isolate and exclude any batch effect. That is where we saw that very high correlation and consistent levels. The situation is really that it stabilizes at the high therapeutic level at 24, and then it stays at that level.
I think it is really important as we think about your subsequent questions, which is the distribution and productive distribution of dystrophin. I think that has really been the key of we talk about these dystrophin levels in a context of everything being the same. I think where dystrophin is produced beyond what its number is, is really reflected going back to that discussion on the Becker phenotypes.
If you remember Becker patients, when we think about that 5% threshold, those patients are expressing that dystrophin level across all of their muscle cells, including their muscle stem cells. That steady state is what's giving them that better clinical profile. I think what we've seen as we went from our preclinical studies to, and that's now non-human primates, and then ultimately in our clinical studies, is exactly what you're reflecting on, which is the quality of where our dystrophin is being produced. Not just the production of functional dystrophin, but what cells are producing that dystrophin is really what's translating to an improvement in muscle health. The exciting part today is really to reflect, recognizing that we now have, and this is what's very unique about these two studies for dystrophin, is we're actually able to look at it in a dynamic effect, right?
Most of the time, we get single shots in time on an assay again that has variability. What we're doing here really is taking biopsies sequentially over periods of time, six weeks, 24 weeks, 48 weeks, for the first time to really study the dynamics of not a dystrophin output, but actually what does dystrophin translate to in muscle health and muscle repair and ultimately maturation, as we've shown today. Getting to those stem cells, which are repairing and regenerating muscle cells, are really key because as you fix a muscle cell, it's kind of like the medicine to move on to the next non-healthy cell. Rather than continuing to kind of see, which we expect to hopefully see, is the vast distribution systemically to get to different muscle groups.
I think what's important as well as we think about an indication on the clinical side, like Time-to-Rise, which is incredibly impressive, which is measuring legs, right? Leg strength, the ability to stand and rise versus the muscle biopsies that are happening in the upper extremity are giving us a good correlation that the distribution we're seeing is not just limited to a specific muscle group, but really doing what we intended to do, which is get broad distribution, and would be highly reflective of the work that we've done in our preclinical data to show in the improvement of muscle. We have 100% survival in the double knockout that's happening because we're getting broad distribution, not just the skeletal muscle, but the heart and diaphragm.
To answer your last question, or second to last question, which is, what should we think about for the other exons? Actually, this distribution is unique to the PN chemistry. I think by not using a conjugate that targets myofibers but really allows the distribution to happen to the myofibers and the stem cell compartment, which is unique about Wave's distribution and ultimately clinical effect we're seeing, that we have seen consistently across the chemistry formats on our other exons. We are excited about what 53 represents, not just for DMD 53 amenable boys, but what it can mean for boys amenable to exon skipping more broadly.
Thank you so much. I have a quick follow-up. Any plans for even deeper subtle architectural studies? Because as you mentioned, location of these things matter a lot.
I thought it was interesting to see that the maturation of the muscles, as evidenced by the locations of nuclei and things like that, are important. Just further subtle architectural EM, whatever studies that may show that your dystrophin that is made is being localized to the right place at the right time to do what it should be doing. Thank you.
No, absolutely, Joon. That is one of the things that we had done in earlier studies. We showed at the six months where we are getting distribution, the dystrophin is going to the right architecture within the myocyte. Again, it is not just the production of dystrophin that you can just quantitate. It is the quality where it is distributed and where it is going.
I think to your point, what's really interesting about having these sequential biopsies, again, a very unique aspect of FORWARD-53 that's not seen historically, is we're actually able to look at those dynamics. As you point out, that maturation of myocyte, where we see those internal nuclei now moved to the periphery, are actually what you see with maturing muscle cells. There is that dynamic effect. There is going to be change in regulation in cells that are maturing and might be how they produce dystrophin differently. I think what we're excited about is moving the conversation in DMD beyond a dystrophin level to really, what does it ultimately mean clinically and functioning for DMD boys?
I think by having these data we have today, I think we get to differentiate not only in the exon 53 space, but more broadly in dystrophin restoration and repairing therapies. Hence, across the microdystrophins in gene therapy, we're seeing the most significant Time-to-Rise relative to three years on gene therapy. I think these data are reflective of that.
Joon, maybe just to add, on the topic of location of dystrophin, I understand that your question was more on the cellular level, but also would remit to not to remind everyone that we see a very good distribution to diaphragm and heart as well in our preclinical studies. We'll continue to do preclinical studies of all of the other exons to understand how they continue to distribute.
Great. Thank you, guys.
Thank you.
Our next question comes from Jenny Gonzalez-Armenta from Leerink Partners.
Please unmute your line and ask your question.
Hi, guys. It's Jenny on for Joe Schwartz. Congrats on the consistent and comprehensive data set that you presented today. Just one question on the inflammation data. That's not something we typically see from exon skipping and gene therapies in DMD. Can you help us understand that a little more, put it into context what's happening with these patients on this front, and what are the implications of reducing these two biomarkers? Thanks.
Yeah, thank you for the question. I appreciate the acknowledgment. As we think about comprehensive data in DMD, it's really exciting, again, as I talk about longitudinal data, to really be able to follow the progress, as Erik really nicely laid out, of how muscle injury happens over time and ultimately leads to fibrosis and loss of clinical ambulation, and be able to actually walk that back.
Not just say there's a statistically significant change on Time-to-Rise at the substantial magnitude, but most importantly, be able to really walk through the scientific explanation of why that's happening. To that point, the first demonstration of reversal of fibrosis. And then, as you point out, that it's not just one metric of inflammation changing. DMD is a chronic inflammatory disease, right? In the absence of dystrophin, even just every step that gets taken creates an inflammatory process that starts degrading and causing necrosis of muscle cells. The ability to not just look at decays as a change in muscle inflammation and biology, but actually be able to tie that back to the inflammatory biomarkers that are actually continuing that cascade, gives us enriched confidence in terms of really changing the pathological process that drives the disease forward.
I think at the beginning of that, it stems from being able to repair and restore muscle fibers off of that dystrophin threshold levels that are required to do that. We look forward. These are great markers and indications to really walk through that histologic process. I think the last thing I'll say is they're not unique in one exemplar. I think what's been really important and meaningful is to look at that consistency across boys on studies. I think that gives us a lot of confidence in moving forward.
Thank you. Our next question comes from Mike Linden from Mizuho. Please unmute your line and ask your question.
Hi, good morning. This is Mike Linden on for Salim. Thanks for taking our questions and congrats on the data.
Now that you're planning to file an NDA in 2026 for N531, what sort of commercial prep should we expect to see across 2025 and into 2026? Similarly, specifically for Europe, what are possible plans here? Would you go it alone or potentially partner in Europe? Quickly, just a clarification, were any of the 11 boys in FORWARD-53 switched from a prior therapy, like a PMO? Thanks.
Start with your first question. Obviously, with these data in hand, and particularly now the clinical data where we have clinically meaningful and clinically statistically significant data, I do think we plan to take those data back to the agency as we continue to discuss opportunities on registrational pathways. Having statistically significant clinical data is exciting, and we plan to do that.
As it relates to building out potential for commercial activities, I think our step one is really building out the robust medical affairs organization and starting to think about, again, those plans over 2025 and 2026. We'll get more updates in terms of how we plan to phase that in. We're excited with these data in hand and looking ahead. As it relates to Europe, we have thought and reflected a lot about Europe and whether or not we would partner. I think those are conversations that we'll pursue after now these data being public. What's really important as we think about the European strategy is we do have now clinically significant data in hand. The ability to think about both in that clinical data beyond dystrophin lets us think about the European opportunity.
To your last question about boys switching, all boys were on this therapy and stable steroids, but were not on other exon skipping therapies prior to receiving N531.
Got it. Thanks.
Our next question comes from Ron Feiner from JP Morgan. Please unmute your line and ask your question.
Hi, guys. I wanted to ask, first of all, congrats on the data. And we wanted to ask maybe what parameters are going to satisfy filing for the months of dosing? Are you going to need to add anything additional beyond the PK? Is there an opportunity to do any additional assessment of dystrophin beyond the biopsies? And what kind of clinical parameters affect that decision? And then I have a follow-up. Thanks.
Okay. Yeah. No, thank you. The current FORWARD-53 study, as outlined, so that's the boys going on to monthly.
The extension is, as we said on the call, that expanded cohort within FORWARD-53 on monthly dosing would be sufficient to support the filing of that NDA in 2026. We will have those data to establish a monthly dosing parameter as we file next year. What I want to add to that, and again, which creates other opportunities, is now as we went to the agency with 24-week data in the absence of the data that we shared today. Being able to share now clinical data that's significant does let us have other conversations as we know that there were other programs where TTR was the basis for an approval. I think looking at these data, it's going to give us another opportunity to engage the agency, not just around dystrophin.
One of the other features that factors into is the powering assumptions to see clinical activity. As we think about one of the other requirements for filing is obviously a confirmatory study underway, we can now think differently about some of those powering calculations to see clinical changes, given that in this early study at 48 weeks, the effect size we saw on Time-to-Rise. I think all of these data are going to inform ultimately the pathway.
Okay. That's very helpful. Maybe, I guess you somewhat added to that, but if you can give some additional color on the timeline of 2026 and not quite early 2026, I guess you just said you will be adding the months of dosing data to this. Is that why it'll take a bit longer than maybe early 2026?
Without guiding into 2026, and you'll have to make a question of why not 2025, one has to remember for the filing, we need two other factors. Beyond getting support for monthly dosing is CMC, right, to be ready for the filing package. Secondly, the confirmatory study has to be substantially underway. When we look at those two features, in addition to supporting monthly, it's why the monthly dosing doesn't change the filing timeline. We'll get further guidance as we get farther, but 2026 is when we're guiding to.
Great. Thanks so much for taking my questions. Congrats.
Thank you.
Our next question comes from Roger Song from Jefferies. Please unmute your line and ask your question.
Great. Can you hear me?
Yes.
Awesome. Yes. Congrats for the data, and thanks for taking the question. Quick ones from us.
The first one is, since you're really building up a very differentiated skipper's therapy for the DMD, so in terms of those muscle and functional endpoints that you just elaborated quite a lot, what will be the key for the confirmatory study? You mentioned TTR may be sufficient for approval. Any other endpoint will be important for regulatory? Also, based on the investigator feedback, what will be the key endpoint will drive the clinical or commercial adoption for the therapy? Thank you.
Yeah. No, thank you for the question. I think obviously for the confirmatory study, we'll build in this series of the same endpoints that we've been looking at. There's Time-to-Rise, there's North Star, 4-Stair Climb. There's a lot of other metrics that we can continue to follow.
I think what we're seeing, whether we talk to the advocacy groups, we talk to clinicians, and even in seeing the regulatory framework shift, is Time-to-Rise is becoming a key determinant and differentiator early on clinical measurements. That'll be a subsequent discussion following these data as we affirm and lock in some of the core clinical measurements for the confirmatory study. Encouraged to see this early time point, and as we said at the call, the largest magnitude of effect on Time-to-Rise, both statistically significant and clinically meaningful. That's going to be important as we move forward. Your last question, I apologize.
Yeah, sure. Another, yes, just to.
Oh, differentiate. Thank you.
Yeah.
How we differentiate on the, yeah, I mean, I think a little bit of that too, as we just referred to on the Time-to-Rise is the key on magnitude is when we look at the exon skipping data from the exon 53 space, we're differentiated on our statistically significant clinically meaningful Time-to-Rise. I think the encouraging piece is seeing it at this early, early time point. As we think about the non-exon skipping therapies that are available to exon 53 boys, meaning gene therapies like Elevidys, we see better Time-to-Rise than on the clinical endpoint.
I think as we historically see the ability to have clinical differentiation be the main strategy, and we think about 50% of the exon 53 boys now currently and 50% of the current exon amenable boys where there are therapies available aren't going on study because there's some hesitancy in terms of lack of demonstration of a clinically meaningful benefit. I think coming into the commercial landscape, not just on a dystrophin number, but having a safe, well-tolerated, and clinically effective therapy that has shown, and I think that's the power of today's data beyond just the clinical measurements, that we're actually restoring, repairing, and reversing damage of muscle injury, I think gives us a highly compelling profile. All of that on a monthly versus weekly basis, I think creates a highly differentiated program.
Great. Thanks. Just one last question related to other exon programs.
Do you have any feedback from the regulator in terms of how you're going to pursue other exon, maybe in a large basket trial? Thank you.
Absolutely. I think that that's one of the conversations that's continuing of how the design of that study, right? The amount of work not just to get into the clinic, but how we can shorten the backside. What I'm encouraged with is that we're having those conversations not in isolation. The advocacy community has been engaging the agency independently on the designs for basket studies and how to more efficiently move multiple exons forward. Wave working in partnership with the advocacy community is working in collaboration to reflect on that. It's in line with how we're thinking about our CTA submissions in 2026 to be in line with that strategy.
Thank you.
Thank you very much. Our next question comes from Ananda Ghosh from H.C. Wainwright & Co. Please unmute your line and ask your question.
Hi, can you hear me?
Yes.
Yeah. Hi, Paul. Congrats on the data. Great data. I have three questions. I think the first one on the function of the TTR, which is absolutely impressive given the new EMBARK data we saw at the NDA. One question is, is there any long-term data which can correlate the TTR, NSAA, and SV95C given the data, given the consistency in terms of dystrophin expression or in terms of where the dystrophin is expressed in the sarcolemma or not? Is there a correlation which one can make between TTR, NSAA, or SV95C?
I mean, I think everybody's trying to, in the long term, put these pieces together with, if we think about that, the TTR, right?
If you think about that as early changes and then that's coming across the composites, I think there is a belief that early changes on Time-to-Rise are indicative long-term that you could see improvements in these other metrics. I think what's encouraging in the data we're seeing today, because we are seeing that beginning on the trend and separation on North Star, is that we would expect to see that over time. I think what's interesting is nobody's seen the early reversal changes that we've seen.
I think that's really, if I go back to the fundamental cascade of establishing dystrophin where it needs to be, getting into the regenerative cells that are being able to restore and make new myofibers, showing that you reduce the inflammatory process, you reduce fibrosis, and not just reduce it, but reverse it, and therefore actually start establishing normal healthy muscle, I think we're going to be able to see for the first time in longitudinal ways. That's what's exciting about the extension study and continuing further, being able to really see that progress of TTR translating because it's fundamentally, and this has been helped by the fact that we uniquely had these different biopsies at time points to look at the change in the disease progress, right? It's modifying the disease. It's ultimately to see that translation over time with an effective therapy that's changing muscle.
I think we're going to get an opportunity to look at that, and we're highly encouraged by the clinical data that we see .
Great. Just to follow up on that question, in the EMBARK data, there was a particular way in which they calculated the external control. How does it translate to the way you have calculated the external control when you are comparing the TTR?
I think it was helpful in our external controls as we have an exon 53 patient population that has been used and actually is very well matched. I think we're fortunate that that group actually correlated nicely so that we do have a benchmark to see those changes with.
Got it. The third is, since you have been focusing on differentiation right from the get-go, which is kind of reflected with the immunohistochemistry data, etc., do you plan to—there was a lot of discussion at the NDA in terms of the use of muscle MRI in the DMD as well as in the FSHD patient population. Do you plan to introduce muscle MRI as you get through the long-term extension studies? Does it add value if you are thinking about it from the perspective of level in the future?
I mean, I think with the data that we have today, we do reflect lots of times. It's always interesting to have more dynamic measurements over time to see that. I think it's historically why people are looking at that, because you do not ever see sequential biopsies.
People are trying to find better ways of looking at what's happening in muscle over time. We're encouraged by that, and we'll contemplate that in future studies. I think on a very functional level, right? An MRI will give you a growth picture of what's happening. I think what's encouraging is at the microscopic level in histology, we have kind of the absolute resolution, and as Erik showed, across boys on all the studies, where we could actually look at what's actually happening at the level of the fiber. I think what's really encouraging there is when you're taking a sample and looking at that and trying to say, "What is it doing?" Doing that over multiple time points, it's highly encouraging to see that at the cellular level before we even get to the macro level.
At the cellular level, we're changing the structure of muscle fibers. Ultimately, as we shared, changing that on a clinical outcome basis. Yes, MRI would be an interesting way to continue to follow that longitudinally.
Very nice. Thank you.
Thank you.
Our next question comes from Tiago Fauth from Wells Fargo. Please unmute your line and ask your question.
Hey, thanks for taking the question. Congrats again. Just a couple of follow-ups for me. You mentioned that you're going to include additional boys on the monthly dosing regimen for FORWARD-53. How many additional patients do you expect to enroll? Are they also potentially going to be a part of the regulatory package that you intend to submit? A bigger picture question, just thinking about capital needs and prioritization, right?
You're going to have a confirmatory trial, potentially expanding the exon skipping platform with other DMD mutations. There's AATD and Huntington's. How are you thinking about that right now in terms of creating the best value path forward? Thanks.
Yeah. I'll take your first question and then your second. Your first, including the more boys on monthly, we wouldn't expect that to be larger than the existing cohort. Those data would give us, and as I said, would be sufficient to include in the filing to support monthly dosing in the label. To your second question, I think we've been very methodical. We've said this over time with a variety of programs in the portfolio and how we think about allocation of capital across various assets. As we said, with HD, we've got the opportunity.
We'll provide further updates this year on the collaboration and partnership opportunities outside the United States and how that brings additional capital into the company. We have existing partnerships with GSK on Alpha-1. As we've said, when we're generating data there and we're moving that asset forward, one, that has potential for not only continued cash inflows, but actually decreases our clinical trial burn and expenses as that program eventually transitions from a cost standpoint to GSK at 100% once we reach the proof of concept portion of the study. As we think about those variety of opportunities, and t hen INHBE, the fact that we have a focus down that conjugated siRNA format that's going to de-risk target engagement, and as we said, be able to give us the opportunity to look at healthy, sustainable weight loss, that's a study we can manage.
As we think about being able to build out and think about the balance of where BD partnerships and opportunities, including, as we've talked about on the call today, whether we do collaborate outside the United States in terms of partnerships, all are ways for us to balance building a fully owned portfolio, building meaningful medicines for patients and delivering them, but also balancing those capital requirements with strategic partnerships and collaborations that allow us to globally commercialize without having to put the expense of building out a global commercial capability early on before we have an established commercial pipeline.
I'm going to say fair enough. Thanks again.
Our next question comes from Catherine Novack at Jones Trading. Please unmute your line and ask your question.
Hello?
Hi. Can you hear me now?
Yes.
Okay. Great. I have a question about cardiac outcomes. You mentioned cardiac expression in preclinical models. Is that something you'd ever explore clinically, understanding that these measurements could be high burden to patients? If you believe this to be a differentiating factor, is there a way to look at that in future studies?
There absolutely is. Thank you because it's one of the areas that we're spending time. Obviously, this study population is less likely to see a change in cardiac endpoints earlier. Encouraged not to see any changes that are detrimental, but being able to follow that at this time point, we're not able to assess that. What we do think about is being able to do that long-term. As we follow boys, the opportunity both on echo and cardiac MRI are two useful tools to be able to think about cardiac function.
In the prior question, I was thinking about MRIs in the context of skeletal muscle, but there are also very highly sensitive tools available to start looking at the cardiac endpoints. I think this really creates an interesting dynamic as we think about the patient population because everybody tends to think about the ambulatory population, boys 5 to 11. The unique opportunity that's really here for a program that distributes to heart diaphragm, in addition to getting the stem cells, means we get to think on one hand of talking about treating it much earlier in the disease setting. Imagine treating boys where we can get into the regenerative cells before they lose any ability to loss of ambulation and even show signs. Being able to help prevent kind of that early onset of the disease process of cascading from kicking in.
Equally important as we think about the later stage of non-ambulatory boys where cardiorespiratory function is critical, we see that as a very unique opportunity and fully intend to explore that because we do think that allows us to treat the entire DMD community from early all the way through the late setting.
Got it. Just one more about the confirmatory study. As you think about designing this, are you open to considering a European regulatory path, or how much does that factor into the way you're designing the functional outcomes of this study?
We think a lot about it. When you run this, you have a shot to look at endpoints that will meet the requirements of global regulators. Obviously, with the accelerated registration pathway, we need to make sure we affirm that from the accelerated approval side.
Yes, we are thinking about endpoints both in the U.S. and outside the U.S. As we said on the call, with these data now in hand with clinical significance, it does let us have important discussions, not just as we said with U.S. regulators, but ex-U.S. regulators. I think we're able to start answering for them important questions, which is the question that always comes up: does dystrophin translate actually to sustained clinical benefit of magnitude? I think we're able to draw a very conclusive line to where you produce dystrophin, how that translates to improvement of muscle health, how that reverses disease process underway in terms of reversing fibrosis, and ultimately how that translates to meaningful high-impact clinical outcome measurements.
I think bringing that to regulators, not just in the U.S., but outside the U.S., is going to be critical so that this global confirmatory study does sup port global registration.
Great. Thanks very much. Congrats on the data.
Thank you.
Our next question comes from Madison El-Saadi at B. Riley Securities. Please unmute your line and ask your question.
Hey, everyone. Thanks for taking our question, and congrats on the extensive update here. It really seems the regenerative data here seems to be kind of one of the take-home messages. I admit I'm still kind of digesting it, but are you seeing regenerative data as well in the non-ambulatory patient? I believe you have one non-ambulatory patient enrolled. And then do you know what percent of stem cells are being transfected?
How do you interpret the decline in the number of stem cells and myofibers with internalized nuclei? And then a follow-up.
Yeah. The first question is the non-ambulatory patient had their biopsies in the early portion of the study, the six weeks and 24. They are not included in this because patients can only have two biopsies during a study. That patient was not in this study from the biopsy standpoint. Still follow-up and still on treatment, but not with a 48-week biopsy. I think your second question, and Erik and I will both answer this, I think is exciting in thinking about what muscle regeneration and turnover means. When you think about the stem cell changes, I think we have to think about that it is not that they go away, that they go back into what you see with normal healthy muscle.
One of the things you see in exhaustion is when you're chronically injuring, you see this shift in the stem cell population that's trying to do its job. It's trying to create repair consistently to make new myofibers and can ultimately become exhausted. When you treat them over time and muscle gets better, they go back to their compartment to wait to be signaled to increase. That dynamic range is a function of actually muscles getting healthier, and you see that with the corresponding shift in internal nuclei. I don't know if Erik's going to have more on this regeneration.
Yeah, I think it's a fascinating opportunity here to really look at on treatment, really at three time points. Remember, we call it the six-week time point. We already have shown that our molecule gets taken up in the cell stem cells to a high degree.
That is kind of kickstarting the exon skipping right away and then starting building the dystrophin that we see then at week 24. And then at week 24, we have a lot of stem cells there. We are really creating this very regenerative environment and tissue rebuilding. We have this 48-week time point where we see that the muscle has really matured. That is kind of the trajectory here where the stem cells play a very important part in getting activated early. As Paul said, when it is maturing and getting healthier and we see all of that less fibrosis, they are less needed because the muscle health has improved. They basically settle down and the whole tissue becomes more mature and healthy.
Got it. Thank you. And then secondly, just quickly, how many additional patients will be enrolled in this new expanded cohort? Just kind of wondering what the total patient exposure requirement is. Thanks.
Yeah. I mean, we would not expect as a whole group, we would not expect this cohort to be any larger than the current number of patients on the study. We are going through that analysis now, but we would not expect it to be different.
Got it. Thanks.
Our next question comes from Ryan Deschner at Raymond James. Please unmute your line and ask your question.
Good morning. Congratulations on the data, and thanks for the question. Based on the results in your comments today, would you expect to continue to see meaningful decreases in muscle fibrosis and necrosis at later time points? Will we see additional fibrosis data in the extension or later in confirmatory studies? I have a follow-up.
Yeah. No, it's an important question because I think the dynamic range in dystrophin, we're so used to seeing these punctuated time points. We got to see it on longitudinal. Unfortunately, we're not going to continue to do biopsies. The opportunity we have to see continued muscle restoration actually comes from clinical output measurements. I think we already saw that, as we said, at the earlier time point, 48 weeks of disease of that magnitude. We expect to see that continue to improve. In terms of the real-world evidence for improvement in muscle fibrosis, improvement in muscle health, we do expect to see that continue to get better. I think that's just a function of realizing that with time and treatment, you just continue to expand muscle groups that get healthier.
I do think being able to see that coupled with exploring and watching things like respiratory function and delaying changes in loss of respiratory function and cardiac endpoints will give us that opportunity. It is why we think about longer studies. Are there other imaging tools that one can use that are non-invasive to look at that? Those are some of the things that we'll continue to explore to continue not to lose this longitudinal data set on muscle biology.
Okay. That's helpful. Also, just briefly, were there any additional decreases in AST or stabilization seen in week 48?
Yeah. There were stabilization, we think about similar to CKs, that those trended. Again, confirming that the CK trends were not in isolation. Again, other signals of improvement of muscle health.
I think what's most important beyond CK, obviously being very important, were the MCP-1 and IL-6. Being able to look at true other inflammatory markers that are showing muscles getting healthy. The best option is looking at muscle histology itself.
Okay. Thank you very much.
Our final question comes from Joon Lee at Truist Securities. Please unmute your line and ask your question.
Hey, guys. Thanks for taking our follow-up question. Also really intrigued by the reduced muscle destruction and turnover as evidenced by the lower muscle stem cells. I get this slide seen in a complete blood count, lower reticulocyte count, which is a good thing. Do you think that could have impacted your dystrophin restorative blood at week 48? Could reduced muscle turnover have led to reduced protein synthesis overall, including dystrophin, which may actually have been a good thing? Thank you.
We think a lot about that, Joon. We're always so careful of trying to hypothesize. We like to be reflective of the data we're seeing. I do think as we're showing a lot of dystrophin coming from various cells, there's dynamic range. In the absence of what historically gets done following these biopsies over time, there are lots of, and particularly what we've seen in an unprecedented way of actually muscles getting healthier and looking at the setting and the dynamics of muscle health improving, there are a lot of other possibilities that could be responsible for that. I think we felt like the stability when we went back and confirmed it. It's within the range. I don't want to say it's going down relative to this change simply because I don't have the data to say that because essentially our data supported that.
It didn't change. It's within the variability of the assay. Again, to Erik's early point, we even ran the orthogonal approach. Twenty-four and forty-eight weeks look similar, right? They're correlated. There are other plausible what happens over time if you look at dystrophin in healthy muscle. We don't have other further time points on the dynamic to biopsy, but there's lots of other plausible explanations. The most important, as you point out, is that all of it's reflective actually on muscles getting healthier and that most importantly, meaningfully translating to boys doing better, which is the most important thing in a DMD therapeutic. Yeah.
Just following up on Ryan's question, I know that you're not doing any more biopsies, but would you be following up with serum biomarkers of muscle health, including CK and LDH and things like that, that could help us gauge the health of the muscles that are being regenerated? Thank you.
Yeah, absolutely. I mean, serum biomarkers are great tools to continue to follow. There are other proteomic assessments that we can try to build in and do over time. We are thinking a lot of ways about not losing the comprehensive data set of really continuing to follow. I mean, this is a really, I think for the field, a comprehensive data set in improvement in muscle health. And it is important boys that participate in this study to help understand what happens in muscle improvement.
We will take every opportunity to continue to longitudinally follow this track improvement and ultimately hope to see continued improvements on clinical measurements. That is the most important thing.
Maybe this is also a good time to remind everyone that after week 48, these boys have transferred to monthly treatment as well. That is also becoming part of that filing package in the future. We will get that serum biomarker from those boys too.
Great. Thanks for taking our follow-up questions. Congrats.
Thank you.
Thank you. There are no further questions at this time. I will now turn the call back over to Dr. Paul Bolno.
Thank you, everyone, for joining the call this morning. I am grateful to every Wave Life Sciences employee for their dedication and focus on our mission and on the patients and families we serve.
Thank you again to the DMD community for your support and partnership. Have a great day.