Good morning, ladies and gentlemen, and welcome to the Sarepta Therapeutics Limb-Girdle Muscular Dystrophy Type 2E functional results call. At this time, all participants' lines are in a listen-only mode. After the speaker's presentation, there will be a question and answer session. To ask a question during the session, you will need to press star then one on your telephone. As a reminder, today's program is being recorded. If you require any further assistance, please press star then zero. Now I'd like to introduce your host for today's program, Ian Estepan, Senior Vice President, Chief of Staff and Corporate Affairs. Please go ahead.
Thank you, Crystal. Thank you all for joining today's call. Joining me today are Doug Ingram, Bo Cumbo, Dr. Louise Rodino-Klapac. After our formal presentation, we'll open up the call for Q&A. I'd like to note that during this call, we'll be making a number of forward-looking statements. Please take a moment to review our slide on the webcast, which contains our forward-looking statements. These forward-looking statements involve risks and uncertainties, which could materially differ from the objective results of operations, trading price of Sarepta's common stock. For a detailed description of applicable risks and uncertainties, we encourage you to review the company's most recent quarterly report on Form 10-Q filed with the Securities and Exchange Commission, as well as other companies' other SEC filings. The company does not undertake any obligation to publicly update its forward-looking statements.
With that, let me turn the call over to our CEO, Doug Ingram, for opening remarks.
Thanks, Ian. Good morning, thank you all for joining us. As you will recall, earlier this year, we reported expression, safety, and other biomarker results from our first three patient cohort for our gene therapy intended to treat Limb-Girdle Muscular Dystrophy Type 2E. Today, our head of gene therapy, Dr. Louise Rodino-Klapac, will provide an update with nine-month functional results for these three patients. With that, I will turn the call over to Dr. Klapac.
Thank you, Doug. Good morning, everyone. For today's call, I will be giving you an overview of Limb-Girdle Muscular Dystrophy Type 2E, I'll be reminding you of the expression data that we showed earlier this year. The new data that I'll be showing will be the updated functional data from 9 months of our LGMD2E trial. To remind you, limb-girdle muscular dystrophies are a devastating group of neuromuscular diseases. They're monogenic, they're rare. There's over 34 types of limb-girdle, accounting for tens of thousands of patients worldwide. There are dominant and recessive forms, with the recessive forms being 90% of all cases. Limb-girdles are progressive, debilitating muscle-wasting diseases. They affect both males and females equally. This is different than Duchenne muscular dystrophy that only affects boys. They affect skeletal muscle, cardiac muscle, have elevated creatine kinase levels.
To remind you, creatine kinase is an enzyme that's leaked into the serum upon significant muscle damage. In LGMD2E, as well as other limb-girdles, we see significantly elevated levels of creatine kinase. Symptoms in LGMD2E often begin before the age of 10, often very early between ages of 3 to 5, but definitely before the age of 10, with a loss of ambulation in teens. This is a more severe form, and it's Duchenne-like in effect in its severity of early onset, as well as a significant proportion of patients having cardiomyopathy and respiratory complications. Death can often result before the age of 30. If we look across our limb-girdle portfolio, we have five internal limb-girdle programs, with three of them being the sarcoglycans. beta-sarcoglycan, which is the protein that is missing or non-functional in LGMD2E, is one of these sarcoglycan proteins.
These are integral in the membrane. They're forming a complex with the membrane that also interacts with dystrophin. This is an important link. When beta-sarcoglycan is absent, you see a reduction in the other sarcoglycan proteins, as well as dystrophin. Correspondingly, in dystrophinopathies, when you see absence of dystrophin, you see a lack or reduction in the sarcoglycan protein. These all form together to form the dystrophin-associated protein complex. The other two limb girdle programs that we're working on are dysferlin and anoctamin 5, and these are important for failed regeneration or muscle membrane repair. We're focusing in today on beta-sarcoglycan, which is important. It forms the core of the sarcoglycan complex and binds to beta-dystroglycan, which is an important protein in the complex as well.
To remind you of our preclinical data, we did studies to look at dosing levels to see what amount of beta-sarcoglycan was important to improve function very early on. Using vascular delivery at a low dose of five times 10 to the 12th vector genomes per kilogram, we see about 20% of the fibers expressing beta-sarcoglycan. This led to significant improvement in function in preclinical models. This really determined the threshold for success in our first phase I trial that we'll talk to you about today. Now I'll go and remind you of the results that we previously showed you on expression levels in our 2E trial. To remind you, this is an open-label trial designed for six subjects with LGMD2E between the ages of four to 15.
Our first cohort was at low dose of 5 x 10^13 vector genomes per kilogram using systemic delivery. This is a single IV delivery. This is a single site with Dr. Mendell, Nationwide Children's as the PI. The inclusion criteria were confirmed sarcoglycan mutations, beta-sarcoglycan mutations in both alleles. Patients had to be negative for antibodies to AAVrh74 and be greater than 40% of normal on the 100-meter walk test. There were muscle biopsies at baseline and at 60 days post gene therapy. To remind you, Limb-Girdle patients are not on steroids as standard of care. In this case, to preclude any potential immune reaction, patients were put on prednisone at 1 milligram per kilogram 1 day prior to gene transfer, were maintained for 30 days before being tapered. This was a phase I trial, the primary endpoint is safety.
We also had expression co-primary endpoint with the threshold for success being determined as greater equal to 20% beta-sarcoglycan expression. We had various secondary endpoints, which included a decreased increase in kinase, and then functional endpoints, which include the North Star assessment for Limb-Girdle Muscular Dystrophy. This is a 54-point scale, so it's different than the North Star assessment that we use for Duchenne in that there are additional measures that account for a 54-point scale in total. The 100-meter walk test, 10-meter walk test, four stairs, and time to rise. We'll be going through each of these in detail when we show you the results. All right. To look at our first three subjects, again, this is cohort 1 of low dose. These are the subject demographics at baseline.
We had a wide range in age that ranged from 4 to 13 years of age, and also a large weight range from 17 to 55 kilograms. We've dosed larger patients in this trial. These are the largest patients that we've dosed throughout for gene therapy within our trials. The mutations were in exons 3 or 4. beta-sarcoglycan is a small gene, and it's only encoded by 6 exons total. Exons 3 through 6 encode the extracellular domain, and mutations in these exons lead to a complete absence of severely reduced expression of beta-sarcoglycan. That corresponds to a severe phenotype that includes cardiomyopathy. Now, as I previously mentioned, creatine kinase levels are increased in LGMD2E.
As you can see here, normal is about 150 units or less, whereas in these three LGMD2E patients, we see significant elevations between 10,000 and 12,000, and relatively consistent between the three patients. Next, this is the expression data that we saw in our three subjects. We're showing at baseline at the top three images, you can see almost a complete absence of beta-sarcoglycan, whereas post-treatment, in all three subjects, we see robust widespread distribution of beta-sarcoglycan that's correctly localized at the membrane. We quantify expression by immunofluorescence in multiple ways. One is just counting the number of fibers. When we did that, we saw a mean of 51% of fibers expressing beta-sarcoglycan. We also looked at intensity, this is the amount of beta-sarcoglycan at the membrane.
When we compare that to normal, we see, as you would expect, 47% compared to normal. In the next slide, I will show you the subject level data by both the percentage of beta-sarcoglycan positive fibers and mean intensity. What you can notice by looking at all three subjects is we see relatively consistent levels between the three subjects, ranging from 42%-63% for beta-sarcoglycan positive fibers, and between 38% and 57% in terms of intensity. We also looked at restoration of the beta-sarcoglycan complex. As I previously mentioned, restoring beta-sarcoglycan is important, but you also want to restore the entire dystrophin-associated protein complex in order to infer function. What we've seen here, we're looking at alpha-sarcoglycan expression, another component of the DAPC.
At the top, you can see again that there's almost a complete absence of alpha-sarcoglycan, whereas post-treatment, you see a significant upregulation of alpha-sarcoglycan at all three patients following treatment. To take it a step further, we looked in more detail and stained the biopsies for both beta-sarcoglycan and alpha-sarcoglycan at the same time. As you can see in the merged image, these proteins are localizing together at the muscle membrane, proving that this is indeed restoring the protein complex. We also quantified the amount of beta-sarcoglycan by Western blot analysis to look at the total amount of protein. We quantified this using a standard curve, using a recombinant beta-sarcoglycan protein, and looked at biopsies both pre- and post- for all three patients. As you can see, we saw high levels of expression. This is the full-length protein.
This is not a modified version in any way. This is the full length of beta-sarcoglycan protein. We can see a mean of 36.1% compared to normal. Again, when we look across all three subjects, we see a consistency between the patients in terms of the amount of expression that we see. Next, this is just summarizing the expression data that I showed you so far. Also, we looked at vector genome copy number, and this is the amount of copies of the vector that are present in the muscle. This just infers and really answers the question, did it get there in the first place? What we see is 0.6 copies per nucleus as a mean across our three patients.
What this really indicates that this copy number that we see robust expression and speaks to the power of the promoter and construct that we're using in terms of the corresponding expression of 51% of normal. Now I will start to show you the new data, and this is the functional data from nine months of the trial. This, again, is our first cohort at low dose of three patients. First, I'd like to start out by talking about the natural history for LGMD2E. This is data that was shared with us by Linda Lowes and Lindsay Alfano at Nationwide Children's Hospital, showing the natural history for LGMD2E patients in the age range of our subjects in this current trial. This is the North Star Ambulatory Assessment for Limb-Girdle Muscular Dystrophy. Remember, this is a 54-point scale.
What you notice here is that between the ages of 4 to 8, we see a relative consistency or plateauing of function in these LGMD2E patients. Whereas around the age of 10, we start to see a significant and dramatic decline in patients between the ages of 10 to 14 in the age range that we see in our trial. This is a small data set, and we have to further confirm this with additional patients, but this really sets the stage for what we would expect in this LGMD2E population. First, we looked at creatine kinase levels across our patients. What we're showing here is data from baseline all the way out to day 270. What you can appreciate is that we see a significant and consistent decrease in CK over the course of these nine months.
At nine months, we've seen 82% mean reduction in creatine kinase. What you notice is that we did in one case on subject 3 at day 180, we saw a peak of CK level that came back to baseline. This was associated with activity. This is consistent with what we've seen in Duchenne as well, that as patients feel better and they start to be more active, that you start to see transient spikes in CK. What's important is that it comes right back down to baseline at the next time point with a resting CK. Overall, these data are dramatically consistent throughout the course of the study in every single patient. Next, this is a busy slide. This is showing the summary of our clinical data at nine months.
The take home message that I'll show you throughout this slide is that at every single measure for all three patients, we see significant improvement in all of the functional tests that we've conducted. We'll walk you through it. First is the North Star Ambulatory Assessment. What you'll remember is that this is a 54-point scale, and from the natural history during the ages that we looked at, you would expect about a 6- to 8-point decline in the NSA-D score. What you'll see here to point out is that we're seeing significant increases in this score. If we look at patient 2 in particular, we saw a six-point gain in his NSA-D score, which remind you, this is the max score. He's essentially reached the normal level, reached normal for the North Star, so he cannot increase in any additional way.
We also saw a six-point gain in subject 3. We look at all of the time-measured functions, time to rise, four stairs, 100 meter, 10 meter, to remind you're looking for a decline in time in all of these functions. Again, here we're seeing dramatic decreases in the amount of time to conduct these activities. If we focus on subject 1, for example, her 100 meter has improved by six seconds. This is a dramatic improvement in this 13-year-old patient. We'll show you a video that really exemplifies this dramatic change that we're seeing on the timescale. To put this in further context, we're going to do some comparisons to natural history. Also, I think the video speaks a 1,000 words in terms of showing how these improvements in these measures translate into real life.
To look at the demographics of our age match natural history group, they're between the ages of four to 15. Generally, what you see in this population is that they're overall slightly younger than our treated patients, and also milder as well. What we're looking at in this slide is the age-matched natural history cohort. This is taking the same patients that we showed you previously and looking at the mean reduction or mean change from baseline in the NSA-D score in subjects between the ages of four to 15. What you can see is a average six-point drop over the course of six months. If we overlay our three treated patients on this, we see a significant increase in the NSA-D score over the course of nine months. Dramatically different than what we would expect from the natural history controls that we have.
All right. Next, we'll show you the videos which really speak 1,000 words. We'll start out by showing you patient 1. To remind you, this patient had a six-point improvement on her 100 meters scale. Let's start with the first baseline video. What you can appreciate in this video is the patient has a gait with difficulty with flexibility and limited hip extension and flexion while she is running. Now if we turn to the next video at nine months post gene therapy, what you notice is the dramatic difference in the quality of her movements and the speed as well. We can see she's running much faster, and she has very good hip extension and flexion, which is really leading to this faster time. Dramatic improvement. Again, this is a six-second improvement on her 100-meter walk/run test.
If we go to our next patient 2.
Okay. Sit back down.
What we tried to do is select videos across all of these functional measures. In particular, this patient, we're looking at one of the North Star Ambulatory Assessment measures, which is getting up from the floor. Our patient, who our youngest patient, at baseline, has significant difficulties getting up from the floor. He's got a lot of instability in his trunk muscles and poor trunk control, and is unable to get up unassisted.
Okay. Sit back down.
Now if we turn to the nine months post gene therapy.
Go.
I think you can appreciate the dramatic difference.
Go.
He gets right off the floor. I wish you could see his face because he's got.
Get up as fast as you can.
a very nice sense of satisfaction on his face, and he's very happy.
Go. Get up as fast as you can
Consistently.
Let go. Get up as fast as you can. Let go. Get up as fast as you can. Let go. Get up as fast as you can. Let go.
Now for our third patient.
Get up as fast as you can. Stand up without using your hands.
This is another component of the North Star Ambulatory Assessment, where a patient is asked to get up from a sitting position without using assistance of their hands. This third patient, if you look at baseline.
Can you show me how you would stand up?
has difficulty getting up and actually can't do the function. If you could see her face, she's saying that she cannot perform the function.
Okay. Can you show me how you would stand up?
Now, nine months later, as we look at the same patient, she can get right up without any assistance. A very dramatic difference, and this is a good example of not being able to do a function, to being able to do it without assistance. This would equate to a two-point change on the North Star Ambulatory Assessment.
Now can you stand up, keeping your feet planted? Good job.
Taken together, what you can appreciate is that we're very encouraged by these early results from these first three patients at our low dose of 5x10^13 vector genomes per kilogram. If we look at our safety assessments since our last update, we've not had any additional safety events since our last update at 90 days. To remind you, we did have two subjects that had elevated liver enzymes early on. One of these was designated as an SAE, as that subject had transient-associated increase in bilirubin. Both of these events occurred when the subjects were tapered off of oral steroids. As soon as oral steroids would re-administer, the elevated liver enzymes returned to baseline, and symptoms resolved within a few days. Then all patients were subsequently tapered off steroids completely by 90 days.
The patients have all been off steroids for at least 6 months at this point. Two of the patients had transient mild nausea, and this was generally within the first week when they just had steroids added. This did not correlate with liver enzyme elevations or other abnormalities. There were no other clinically significant laboratory findings, no decreases in platelets. Just to summarize this data so far, the construct that we're using for LGMD has been optimized. What you notice using our platform approach, we see a lot of similarities between our microdystrophin program and this LGMD2E program. We're using AAVrh74, which we've found efficiently transduces all muscle types. This includes skeletal muscle, diaphragm, heart. We know that AAVrh74 has low preexisting immunity across both the Duchenne and Limb-Girdle population. We've specifically chosen this MHCK7 promoter.
This allows for high expression in the heart and skeletal muscle, leading to these high levels that we've been demonstrating not only in this 2E trial, but also our microdystrophin trial. These preliminary results are very encouraging, that across a systemic dose of 5x10^13 vector gms per kilogram, we're seeing expression levels that are reaching 51% normal. These expression levels are restoring the DAPC complex, leading to a substantial reduction in CK. This is leading to consistent improvement across all three patients in all functional measures. The safety profile we've seen so far supports dose escalation. What are our next steps for this program?
Next step is to conduct a fourfold increase to do our cohort two, which is at a dose of 4 times, which is equivalent to the dose that we're using in our microdystrophin trial. From those two doses, we'll select the final dose for our registration trial. Coincidentally, or in parallel, we're engaging with global regulatory agencies to discuss pivotal trial designs. LGMD2E is a rare population, we want to make sure that we're taking advice from the agencies on how best to design these trials in a smaller population. Finally, just to remind you of our pipeline. We have a robust pipeline in LGMD. We have five internal programs, we're using a platform approach, again, where we're using the same AAVrh74 vector, the MHCK7 promoter in all but two cases, using a muscle-specific promoter in the others.
Really what we can say is that this first LGMD2E program is pioneering the way for success with these other programs, and the learnings can subsequently be applied to accelerate the pathway for the rest of these programs. With that, I will stop, and we can take questions.
Thank you. Ladies and gentlemen, if you have a question at this time, please press the star followed by the number 1 key on your touch-tone telephone. If your question has been answered or you wish to remove yourself from the queue, please press the pound key. Once again, to ask a question, please press star and then one now. Our first question comes from Salveen Richter from Goldman Sachs. Your line is open.
Good morning. Thanks for taking my question. Just in regard to the registrational pathway here, and I recognize that you're in discussions with the FDA, but is there flexibility here that you could use various components or composites of the functional endpoints that you've presented today? Maybe you could just walk us through that and as a follow-up?
This is Doug. Real quickly, let me say that it is our intention to meet with the agency in the near future and to have a discussion about the development pathway first, of course, for our 2E program, and then beyond that to the rest of our limb-girdle programs. We have views about ways in which one might be able to accelerate the development of these programs, given the fact that we are dealing with a serious monogenic disease and the gene therapy it issues replaces the actual native protein. Until we have those discussions, I think it would be premature to speculate on the exact development pathway. We certainly think there's opportunities to shorten development or to accelerate development, but that's going to require some discussions with the agency before we can discuss that with a sense of confidence.
Thanks. Then with regard to the other limb-girdle muscular dystrophy programs, could you just give us a sense of when you might start those and take them into the clinic and how you might design those trials given the read-through here?
There is a lot of read-through between the programs. Five of the six Limb-Girdle programs, as Dr. Louise Rodino-Klapac noted, use the same vector, and many of them use the same promoter, and all of them express the native protein. We will come back early next year and discuss the development pathway for not only this 2E Program, but for the rest of our Limb-Girdle programs. We have a lot of work to do in that regard, and we obviously want to work with a sense of urgency that matches the urgency that these families with these various Limb-Girdles feel. We need to think about a few things. As always the case with gene therapy, we need to work on manufacturing.
We are doing work right now, and I would say we're making very good progress on manufacturing process for the Limb-Girdle programs with our partner, Paragon, and with our own internal expertise, both in process development and analytical development as well. Of course, we also need to come to some views on the development regulatory pathway, and that is going to require an informed discussion with the agency to take their input and guidance. We'll get that all together, and we will come back and provide additional guidance on the pathway forward and the timelines in 2020.
Great. Thank you.
Thank you. Our next question comes from Martin Auster from Credit Suisse. Your line is open.
Hi, this is Martin from Marty. Congrats on the encouraging data. I guess two questions from me. First, would you be able to disclose how many patients you've dosed at the high dose at this time? In terms of the decision on which dose to use in the pivotal study, will it be based on the biopsy data and safety data, or are you also planning to wait for some functional data from those high-dose patients? Thank you.
Go ahead, Louise. Answer the second question.
Yeah. The dose will be selected. What we want to see is the maximum tolerated dose. We're very happy and encouraged with what we're seeing at the low dose so far, but we'll explore the higher dose. We'll look and evaluate both safety and function, and that's how we'll base our selection for the pivotal trial.
On the dosing, because remember, we're going to do one additional three-patient cohort. As Dr. Dino-Clayback noted, it'll be at one additional higher dose, actually four times higher at two times E to the 14. On that basis, as Louise said, we'll make the decision on which of the two doses has the right combination of tolerability and expression efficacy. We intend to dose those patients as soon as possible. We're actually screening patients even as we speak, so that should all occur fairly rapidly.
Thank you. Our next question comes from Alethia Young from Cantor Fitzgerald. Your line is open.
Hi, this is Eileen on for Alethia. Thanks so much for taking the question, and congrats on the data. Just one, if you could comment on how the data impact your view on the use of gene therapy in DMD, particularly as we think about older patients with the two 13-year-olds in this study. Thanks.
Yeah. In a lot of ways, it encourages us and makes more powerful to look at both older patients, larger patients. Just looking at what we'd expect from these two 13-year-olds, we really would expect a decline during this time point. What we're seeing is a reversal. We're seeing an improvement. We're not seeing just the stabilization of baseline. We actually saw improvement. I think that although we can't directly compare results between the two and how larger, older Duchenne patients would respond, I think gives us a lot of confidence leading into that we're going to see in terms of the results, positive results, and then also as far as safety.
We also get, remember, there is a lot of similarities between these various constructs, both the capsid and the AAVrh74, as well as the promoter, MHCK7, this heavy chain promoter that Louise and Dr. Jerry Mendell chose to use with these constructs. This is additional evidence that suggests, again, that it appears that we can dose at high levels, even in larger children safely, and that we get very good expression. I will remind you that the dose here was one-quarter of the dose that we used with Duchenne muscular dystrophy. Notwithstanding that, we got very robust expression, 51% on dystrophin-positive fibers and 36.5% on Western blot. I think we can't take it too far, but there is a significant amount of potential read-through to the microdystrophin program, giving us additional confidence there.
There's a lot of read-forward to the other limb-girdle programs, five of six of which share the same capsid. At least two of the other ones share the same promoter, and all of them share the same designers.
Thank you so much.
Yep.
Thank you. Our next question comes from Brian Abrahams from RBC Capital Markets. Your line is open.
Hi there. Thanks for taking my questions. Congratulations on the data. Two quick ones from me. Any more specifics that you can give us on where you stand with respect to commercial scale-up and timetable for supplying the market in Limb-Girdle? I'm sort of curious how your ongoing experience with golodirsen has influenced your thoughts on the potential for an accelerated path in Limb-Girdle. Thanks.
On the first one, we had good work on process development and analytical development on the limb-girdle programs generally. I'll have additional updates on that in 2020, early in 2020, hopefully. Remember, because the processes are nearly identical between these programs, both the microdystrophin program and the limb-girdle programs, as we're doing the same thing in all the programs. We're evolving from HYPERStack over to iCELLis units, both at Paragon and Brammer. The learning that we get from microdystrophin will significantly read through to the limb-girdle process development as well. The short answer is I'll come back and provide additional updates early next year, but we're making very good progress across all of these programs. The most advanced of which from a manufacturing perspective is, of course, our microdystrophin program. We're making good headway there, and I'll come back with updates next year.
There is no read-through from the, in my view, there's no read-through from the Golodirsen CRL to the views on any of these issues here. This is an entirely different part of the agency and entirely different issues. That issue really was unique to Golodirsen and with some read-through to casimersen as well, but it doesn't really read through in any way to this. Again, I don't want to get out ahead of our skis and start suggesting that we have the answer on the exact pathway for these limb-girdle programs. We do need to have discussions with the agency, and they need to be evidence-based discussions, and we'll come back and talk to the community once we have those. I will note a couple of things.
Note first that this is a, as is the case with Duchenne muscular dystrophy, a serious monogenic disease that results from a single missing protein that is extremely serious, life limiting, and very, very often life ending. That the gene therapy here is replacing the actual native protein, the absence of which is causing the death of these children in this extremely rare disease. With that said, I think there will be the opportunity to have discussions with the agency about the pathway forward and how one can be thoughtful about accelerating the pathway forward if we have robust expression and good correlates between that native protein and the restoration of function and benefit. We'll come back and have full discussions about that next year.
Thanks, Doug, and congrats again.
Thank you so much.
Thank you. Our next question comes from Debjit Chadha from H.C. Wainwright. Your line is open.
Hi. Thanks for taking my call. This is Aaron on for Debjit. I just have a couple questions. I'm sure you guys saw there was a recent study of 395 U.K.-based DMD patients, and they were able to classify patients into different progression trajectories based on their baseline SAA scores, rise from floor, and 10-meter walk/run. Do you think there could be a similar story with LGMD, and do you think you might incorporate some of these findings into clinical trial designs?
Louise, do you have a view on that?
Limb-Girdle, there's certainly differences in findings. As the North Star assessment was adapted for this population, additional measures were added. Certainly, one of the things that we're considering is looking at trajectories in patient, given the population, and something that we'll continue to take guidance on. We're looking at all of that as we assess our clinical development plan, and certainly looking at the Duchenne data that's relevant, but also with a mind's eye that there are important differences in Limb-Girdle.
Okay, thanks. Just real quick, could you tell us anything about the commercial supply study for microdystrophin? You're still planning on initiating the study prior to unveiling the data for the ongoing clinical supply study in the first half of 2020?
Yeah, our plans remain exactly as they were last time we talked, and we've made additional progress in that direction. As one might recall, at our last earnings call, if I'm not mistaken, we increased the N on what we call Study 102 to 40 patients, increasing the powering of that to nearly 95%. We're working on that this year. Our goal, since we have additional time, our goal was to commence Study 3 in the first half of 2020, and all of that remains on track.
Okay, great. Thank you, guys. Congrats on the day.
Thank you. Our next question comes from Matthew Harrison from Morgan Stanley. Your line is open.
Hey, good morning. Thanks for taking the questions. Two from me. One, can you just talk about what the plan is to demonstrate an impact in cardiac tissue in these patients, and how important you think that is, especially for some of the older patients who might already be declining? Second question is just around natural history data. You pointed out that the natural history data is maybe not as robust here as DMD. Just maybe remind us of the plan here and how important that is in terms of regulatory discussions. Thanks.
In terms of the cardiac delivery and expression, we're obviously monitoring cardiac activity. As said, we're doing cardiac MRIs at baseline and one year post. Really the impact of the cardiac success will be shown over the years as we start to look at these patients in more detail and realize that they're not succumbing or having the cardiac defects that we see in similar patients. We're definitely monitoring that. We can't do cardiac biopsies, but we're certainly monitoring cardiac activity through MRI, and we expect to see a significant improvement or absence of any cardiac defects in these patients. To your point, in older patients, this is a really significant part of the disease. Really, in a sense, not only are we doing a gene therapy trial for muscular dystrophy, but we're doing a cardiomyopathy trial in a sense as well.
The second question was about the.
Natural history.
natural history data. Yes, to your point, that we don't have the robust, in terms of numbers, amount of natural history with limb-girdle in general and especially 2E. This is something that we are certainly working with Nationwide Children's on collecting additional data. In a broader sense, we'll be doing a larger natural history study in not only LGMD2E, but also multiple limb-girdle subtypes, especially the ones that we're working on, to really gather additional data to inform both our trial design and ways to limit the amount of patients that would have to be included to see significant effects.
The one thing, I apologize if Dr. Louise Rodino-Klapac has already said that, but I would just remind you, and I think most people already know, which is while we can't take biopsies of the heart, it wouldn't be obviously ethical. There is a unique promoter being used here that was chosen specifically because of its preferential expression in the heart. As you may recall, in animal studies, we're seeing about 120% in the heart of whatever we see in the cardiac muscle. Gives us a lot of confidence that even before we begin to see manifestations of the benefit in the cardiac muscle, we're going to have very robust expression and very durable expression in the heart, given what we're seeing in the skeletal muscle.
Thank you. Our next question comes from Tazeen Ahmad from Bank of America. Your line is open.
Hi. Thanks for taking my questions. Maybe one about, to the extent that you can comment, do you have a bit more color on how older patients in the study performed, let's say before they started on gene therapy? Were they already showing signs of decline? Maybe as a follow-up as well, in relation to natural history, are there specific differences between exon three and exon four in how that impacts how the disease progresses? Thanks.
I'll answer the second question first. In terms of the exons three and four in the data sets that we have, we know in generally between exon three through six that we see a significant proportion of disease that is more severe than the others. We don't have the specificity to look at three versus four. We know that we see almost a complete absence of expression, and this corresponds to a more severe disease. In terms of the patients that we look at, we don't have a long trajectory on all the patients that were enrolled in the trial. What was clearly evident from the videos that we showed and their baseline scores is that these patients were significantly affected at baseline. These were not what you would expect, certainly divergent from what you would expect for their age.
When we look at the natural history, in line with what we expect, actually more severe than natural history in terms of their baseline NSA scores and their baseline function. I think you can just even appreciating from the videos, these patients were definitely affected.
You can see it objectively. If you go to the slide deck, you'll see the baseline immunohistochemistry images for all three of these children. As you'll see, they are basically entirely bereft of the protein of interest, which would certainly suggest that they're extremely severe versions of Limb-Girdle 2E.
Doug, would you think that in your advanced study, you would want to have more of the severe patients enrolled, or are you going to try to do evenly across age?
We're not at a place where we've made those decisions right now. Really, we need to sit with the agency. First of all, this is an extremely rare disease. That would by itself assume that we would even have the luxury of choosing particular subsets of Limb-Girdle 2E. Beyond that, of course, we've got to be careful not to choose subsets that end up creating issues for us from an access perspective. Our goal here is obviously if this therapy works, we're going to hit children around the world, children and adults around the world that have 2E and then the other limb girdles. We've got to sit with the agency and talk to the agency about the development pathway. We will do that, and we will come back next year and provide updates.
Thank you. Our next question comes from Ritu Baral from Cowen. Your line is open.
Hey, guys. Thanks for taking the question. Question on the next dosing cohort. Doug, can you confirm that you have the clinical supply for that dose manufactured, or is that the gating step for starting that higher dose cohort?
Yeah, we have it. We have the supply. We're screening the children, it should happen expeditiously. We have the supply.
Okay. What is the steroid dosing plan for these patients? Are you going to keep the extended steroid plan? Are you going to up the dosing? Can you talk about that?
Sure. We're going to keep the same steroid dosing plan, one milligram per kilogram per day. That we'll be closely monitoring it, extended as needed, as we did in the first cohort, corresponding to any liver enzyme elevation. We closely monitor and adjust as needed.
Is there any stopping criteria for liver enzyme changes?
No, there's no stopping criteria.
Got it. As I look at the data detail of the functional data, is there anything I guess, is there any pattern that stands out with the younger patient? I believe that was the four-year-old, patient 2. That patient had, I think, the most remarkable 100-meter run time improvement. How much could we think about that just being a four-year-old growing versus potential improvement in younger patients?
Yeah. I guess we could answer that in two ways. If you look at the natural history in the data set that we have, we would not expect improvements in this age group. To your great point, this 4-year-old did improve dramatically in his running times and also his North Star Ambulatory Assessment. He's basically maxed out, so we could not see any further improvements. Based on the natural history, we definitely would not expect these changes at this time point. Just thinking back to the video at baseline, you can see that he definitely was dramatically affected, had very significant instability in his trunk, not able to get off the floor. This certainly wasn't just a learning to test. This was a true improvement in strength that was able to make him get up from the floor without assistance.
Does this suggest to you that you may want to enroll younger patients in the next cohort or going forward?
I think overall, looking at this cohort, 4 to 13, we're very encouraged by the findings that we see in not only the youngest patients but the older patients as well. I think these are questions that were begging to be answered, and I think that we're now starting to get the answers as these older patients can not only just be stabilized but also improved. I don't think that just enrolling younger patients will be the answer. I think we can have significant benefit for all patients.
No, one thing I would note.
Got it. Thank you.
Look, this is three patients. We need to be careful to not overinterpret, but would note that every single patient, every single functional endpoint improved. Frankly, these girls, these older patients should be in decline right now. It would've been extraordinary if one could've arrested that decline. The fact that we're seeing functional improvements there is really exciting as well.
Great. Thanks for taking all the questions.
Thank you. Our next question comes from Christopher Moran from Nomura Instinet. Your line is open.
Good afternoon. Thanks for taking the question. Thinking about dosing the patients on the high-dose arm and their screening, are you looking at a wide age range of patients there? Are you still going to dose the 13-year-olds and beyond? Just with respect to the preclinical data in dose response, just remind me if you saw a dose response in, say, metrics like vector copy number in animal models. I have a follow-up. Thank you.
Can I take the second question? The second question was are we seeing a direct dose response in animals?
Yeah. In our animal models, we definitely did see a dose response in terms of dosing and corresponding function. Importantly, why we chose our threshold of 20% is that we saw significant improvements at that dosing level. I'll start with the first question. We are enrolling the same between ages of four to 15 for the second cohort, so we're not changing the age of enrollment at all.
Okay. Just thinking about the functional endpoints, what's the minimal clinically meaningful improvement on the North Star or other functional endpoints that you measured? Does that change across age groups? Maybe finally, just thinking about the three sarcoglycanopathies you're going after with your gene therapies here, I guess SRP-9004, SRP-9005. Would you consider a trial incorporating all three, so SRP-9003, SRP-9004, and SRP-9005 given the rarity of the disease and the fact that you're expressing the native protein, and phenotype probably looks pretty similar across the patients. Thank you.
I'll touch on the second one first, just simply say that is certainly one of the many things that we've pondered when one thinks about developing rapidly these programs. It will require us to have discussions with the agency before we have any confidence on that. I would say, just touching briefly, and then of course Dr. Louise Rodino-Klapac really ought to answer the first question. To the question, what level of improvement would be meaningful? I would at least argue that that might actually be a false argument because frankly, in these older patients, they're supposed to be declining. Had we arrested decline or significantly slowed decline, one could've assumed that that would be very meaningful. I can only imagine how much more we want to get a child into a therapy that could stop the decline of this ferocious disease.
We're not seeing that. We're actually seeing improvement. With that said, Louise.
Yeah, no, I agree with Doug. I just would add that in this early stage, we're still evaluating all that once we gather more natural history about it, do more predictions. Just thinking about it from a practical level, a two-point change on North Star is going from not being able to do one function to being able to do it, that in and of itself is significant. Being able to get off the floor without assistance, that's significant. I think when you think about it, we're trending towards evidence of these clinical trials as more real world that accounts to improvements in their daily living. From that perspective, those changes of just two points and above are significant in and of themselves.
Thank you. Our next question comes from Gena Wang from Barclays. Your line is open.
Hi. Thanks for taking our question. This is Peter for Gena. Just two quick questions from us. First, understanding that natural history is pretty variable and you have limited data set. For slide 20, could you give a sense of how comparable these are in terms of the patients that were being treated versus these natural histories? How do you have the confidence that these are representative control sets?
That's a good question. The comparability of the natural history cohort and their severity versus the severity of the children in our study, I suspect would be different.
Sure. Yeah, I think as I mentioned with these patients, if you look at the overall mean of their age, they're slightly younger, and if we look at their North Star, slightly milder in terms of their baseline characteristics.
Do they have same sort of molecular characteristics?
They're missing the same protein. I think you're asking if we know.
No, same serotype.
Yeah, we don't have that information.
We're not aware that there's a more severe phenotype than mutations on exons three through six, right?
Right.
Thank you. Our next question comes from Vincent Chen from Bernstein. Your line is open.
Congrats on the data, and thanks for taking the questions. A couple of them for me. The first is, recognizing the natural history data is limited, what's your current sense for range of variability in patients with LGMD2E? Looking toward a pivotal trial, recognizing there's a range of potential paths to approval, if you did have to power a trial for function, what would that imply for a number of patients needed to sufficiently power a LGMD2E pivotal trial as compared to a DMD trial? The second is, thinking about the endpoints, just help us understand how does the NSA-D and LGMD differ from the NSAA scale for DMD? In your discussions with KOLs, what's their sense for the potential degree of placebo effect in the two scales?
On the first one, let me say again, I hate to be a broken record on this, we've really got to sit down with the FDA and talk about the development pathways for 2E. On top of that, this is a very rare disease. The very fact that sort of pondering how one might power, for instance, a placebo trial for 2E with them, it raises the very point that we've got to find a better, more thoughtful, more expeditious pathway for these patients. We will have discussions with the FDA, come up with views on that, and come back to the community with the views. Then on the second issue.
Yeah. Just in comparison of the traditional NSAA that we use with DMD versus NSA-D for limb-girdle. The NSA-D just includes additional measures. For example, some of those are getting up from a squatting position. Some of these are looking at left versus right. Just additional measures in addition to the normal 34-point scale that we see. In terms of this scale has been used, a similar scale in a significant cohort of distal neuropathy patients, for example, and now it's being incorporated to many limb-girdle natural history studies across the board. It's definitely been endorsed by the larger community as appropriate for this limb-girdle community.
Thank you. As a reminder, ladies and gentlemen, in the interest of time, we do ask that you please limit yourself to one question. Our next question comes from Joel Beatty from Citi. Your line is open.
Hi, thanks for the question. Could you discuss where the liver enzyme elevations in the two older, heavier patients? If so, what are the implications of that for the higher dose cohort?
Yes. The two liver enzyme elevation were in the larger patients. As we stated before, we'll just continue to monitor patients very closely, and as soon as we see any elevations in liver enzymes, we'll either increase steroids or if it's happening during a potential taper period, we'll reintroduce steroids. We're definitely monitoring and tapering over a longer period of time compared to the first cohort to make sure that we don't see these increases in liver enzymes.
I will note, again, I think everyone knows, but this seems to be something that will occur at times with full body infusions. We've seen it in a microdystrophin study, and we've seen it here, but they all have responded to steroids, increasing the steroids, and went back to baseline. While it's certainly something we have to take very seriously and monitor closely, it does appear to be a manageable aspect of these gene therapy trials.
Thank you. Our next question comes from Joseph Schwartz from SVB Leerink. Your line is open.
Great. Thanks very much. In which types of patients, or in which ways do you think that a higher dose can offer a greater improvement above and beyond the benefits that you've seen now at the low dose? Are there certain functional areas or types of patients that you think have a particularly good opportunity to benefit more than others? Is the goal of a higher dose more about providing longer-lasting effects?
I'll broadly answer that. Before we lock down the dose and proceed and get informed not only about 2E but about some of the other limb-girdle programs as well, because I believe this dose selection is going to have read-through. We want to make sure that we have the most robust expression possible. We have the opportunity to do that with a higher dose, and so we're going to take that opportunity. I think generally speaking, the answer on expression is more is always better, certainly. Before we lock that down, we want to have the most robust potential expression, where we are frankly very excited about the fact, and we certainly were earlier this year, that even at what we thought was the lower dose, we got results that were multiples better than what we had predefined as success in the trial.
We don't want to just declare victory yet. Let's do one higher dose, compare expression and tolerability and safety, and then make that dose selection between the two. It is interesting to note, why do we keep focusing on expression? Conventional wisdom says focus on function. I would remind you that this is a monogenic disease that results in the lack of protein, and it is the only reason that these children are degenerating and dying. If we can restore the actual native protein, then it is exceedingly logical that the functional benefits are going to flow because we've restored the very issue that exists. Getting the highest expressions that are reasonably possible with a good safety margin has to be our ultimate goal, and that's the way we're going to look at these two doses.
At least you can correct me if I've-
Nope
misstated.
Exactly.
Thank you. Our next question comes from Danielle Brill from Piper Sandler. Your line is open.
Thanks, guys. Congrats on the data. I'm curious what the ages of initial onset of symptoms were across the patients, and also how variable were baseline symptoms like presence of muscle pain and macroglossia?
Did you have that answer?
Yeah. We don't have that information as far as the age of onset in these patients. Certainly our four-year-old, we know that the age of onset was significantly early. We don't have that information for the two older patients.
Thank you. Our next question comes from Anupam Rama from JPMorgan. Your line is open.
Hi all. This is Tessa filling in for Anupam this morning. Congratulations on the updates here from us. At the lower dose with data today, anything in terms of improvement you are seeing in patients that you don't think are captured by the scales you've used? Just one question on the high dose cohort. You are in the screening phase now. Will you aim to have these patients age match to cohort one, so two older patients, one younger patient, and similar baseline for the comparison, given variability in the population that has been previously noted? Thanks so much, guys.
Yes, to answer the question, one is that we'll be doing these, again, between ages of 4 to 15, so we won't have an age match exactly to our first cohort. I think to your other question, as far as beyond what we've seen with the functional scales, we have a lot of anecdotal data from the patients in endurance. I would say it's something that definitely stands out for these patients from the families is that they're able to do activities for a much longer period of time, and they certainly see differences at school. I think I remember hearing from Dr. Mendell that one patient in particular was able to carry her backpack for the first time, and that sounds like something that's maybe not meaningful, but being able to pick up your own backpack and carry it to school was significant for this family.
Certainly we definitely hear these anecdotal stories about endurance and being able to do activities they couldn't before.
One of the values of these videos, arguably anecdotal though they are, is that one sees qualitative issues in the video that don't get captured by the necessary stilted approach to taking, for instance, timed tests and the like. You may recall with our Duchenne program and microdystrophin when Dr. Jerry Mendell spoke last year about those videos. He was able to comment, for instance, on the reciprocal climbing that the children could do that they couldn't previously do, and the fact they didn't use the rail, none of which is captured, or even the quality of the way they run isn't captured. We're actually reflecting on some of these issues.
In addition to simply using videos and the like, we're actually pondering if there are ways as either an experimental measure or a secondary measure in the next trials that we do, if there's ways to capture that. There are ideas out there, wearables and the like that we're going to think about because I think that by necessity, these functional endpoints boil things down, for instance, to timed tests and the likes and sometimes miss some of the obvious qualitative issues. It's one thing to hear about NSA-D, for instance.
It's quite another to see the video of that boy who already at four years old cannot get up and then pops up with a massive smile on his face, or that 13-year-old girl who could not stand up in a chair, and if you had seen her face, you would see was embarrassed about the fact that she couldn't possibly do it and had to tell them that she wasn't able to do it. To see her actually being able to do it. We're going to try to find some objective way to capture what currently would be qualitative issues as we think about not only these limb-girdles, but of course, our microdystrophin program.
Yeah, just to add, Doug's commented on videos 2 and 3, if you think back to video 1 where the 13-year-old girl was running, the quality of her movement was significantly improved as she had much more flexibility in her hips. I think these are the types of things that aren't captured necessarily just on timed scales, the quality of movement. To Doug's good point, we're going to certainly evaluate ways that we could look at this and capture these measures as well.
Thank you. Our next question comes from Lisa Baco from JMP Securities. Your line is open.
Hi, this is John on for Lisa. Thanks for taking the questions. Just one from me. I'm wondering, what do you hear from patients as far as what they care about as far as functional improvements and what could be measured in a study? I remember from the recent national conference that patients would say things like, "I can walk just fine once I get going, but getting up is the real issue." In 2E, what do you want to key on as far as what you're hearing from patients would be the most meaningful change for them?
Yeah, I think you really hit the nail on the head and things that we hear is getting up from a chair. To your good point, I hear that all the time from limb-girdle patients, and often they'll continue to stand because they don't want to sit down because they don't want to get back up again. That's a really critically meaningful point to them. Our patient three that was able to get up from the chair, that is significant. The other story that I told about picking up a backpack and taking that to school, that was important. Those are the types of things that definitely matter to patients. That's what we've heard anecdotally.
I will say one thing. I just would remind us that the goal of this anyway is to replace the very protein the absence of which is killing these children. This is not a palliative therapy. Obviously with palliative therapies, that's a really important thing to think about, or a symptomatic therapy, that's an important thing to think about is this particular restoration of addressing this particular symptom, an important one. Here, the goal is frankly much more ambitious. The goal is to do full body infusions on children who have a mutation on the gene that codes for beta-sarcoglycan, the absence of which is going to cause them to degenerate. They're already degenerating, very likely to take their life.
Our goal is to restore that in such abundance that we can arrest decline, and at least in these early cohorts, perhaps provide function that has even been lost already.
Thank you. Our next question comes from Tim Chiang from BTIG. Your line is open.
Hi, thanks. Louise, Doug, I was just looking at the clinical trial protocol for this study. I guess the upper limit for age is about, what, 15 years? Are there any non-ambulatory patients at that age with 2E? I was just sort of wondering.
There are patients that are non-ambulatory in that age group, and so the inclusion criteria of being able to walk greater than 40% on the 100-meter timed test excludes those patients that are non-ambulatory, unfortunately, in this age cohort.
Just in some of the other limb-girdles, would you consider enrolling non-ambulatory patients?
The answer is yes to that. Let's be clear, we're talking only about dose selection for the next cohort. We don't intend to leave behind non-ambulatory Limb-Girdle 2E patients either. We have a criteria for the next cohort that does require ambulation. We will find an approach to our development path, and come back and talk to you about it, that will include non-ambulatory patients. First with 2E and then with the rest of limb-girdles. I know you guys know this, but so we're clear, and for microdystrophin and Duchenne muscular dystrophy as well. The next trial that we do, what we call Study 3, will include non-ambulatory patients. We're not going to leave them behind.
Thank you. Our next question comes from Hartaj Singh from Oppenheimer & Co. Your line is open.
Great. Thank you for the question. I just had a quick question. Maybe here I'm just confused, and I apologize for that if I am, because I think your protocol originally had six patients in this next cohort, right? Three at the higher dose, potentially three placebo. You were going to report that nine patients in total. Did that change? Are you just going to the high dose cohort, or are you still planning on including the three placebo patients? How will that help you sort of with your discussions with the FDA once all the nine patients have read out? Thank you.
Yeah, originally the protocol did anticipate a placebo patient in the second cohort. We've modified the protocol and we're just doing three patients at high dose. We'll have a total of six patients in this trial, three at the low dose, which we've already done, and three additional at the high dose.
Thank you. Our next question comes from Tim Lugo from William Blair. Your line is open.
Hey, this is Lachlan. This is Tim. Thanks for taking the question. I was just wondering, given the variability in CK, if you have any plans to look at other biomarkers to assess durability. Obviously there are limitations as to how frequently you can conduct a biopsy, but do you have plans to re-biopsy at some point to look at the durability of expression?
We are not looking at doing another biopsy in the near term for the simple reason that it borders on challenging from an ethical perspective to put these kids through another biopsy. Simply because there is no evidence from any of the preclinical models that would suggest in any way that you would have any diminution in durability over any of these reasonable period of times. If you look at animal models, in the mouse model, we would see durability for the entire normal life of a mouse. In the golden retriever models, we've been able to see full durability for as long as we've been able to look, which is eight years. This is obviously, I'm being a little bit agnostic. It's not Limb-Girdle 2E, but it's the neuromuscular generally. In the non-human primate, it's gone out much longer even still.
The issue is simply the time frames we're talking about are not time frames where we would rationally even worry about durability. Re-biopsying these kids would be a burden that would be unjustified.
Just to add to that, you mentioned particularly CK, and CK is variable. If you look at the data that we presented, we actually see consistent drop in CK over the course of the study in all three patients. Remembering that these patients are off steroids, there's no confounding factor at all. We did see very consistent results using CK as a biomarker in this study.
Thank you. I am showing no further questions from our phone lines, and I'd like to turn the conference back over to Doug Ingram for any closing remarks.
Well, thank you all for joining us today. I want to thank, obviously, Dr. Louise Rodino-Klapac. I would also be remiss if I did not take a moment to thank Dr. Jerry Mendell at Nationwide Children's Hospital. He is the principal investigator for this limb-girdle trial. He is the principal investigator for our current microdystrophin Duchenne trial. He was the investigator for the SMA program at AveXis. I don't think I'm being hyperbolic when I say that because of Dr. Mendell's dedication and unbelievably hard work, families of rare neuromuscular disease have real evidence-based reason for hope. If successful, many lives will be saved. I really want to make sure that we linger and thank Dr. Jerry Mendell today, as well as Louise.
With that said, we're very pleased to see the consistent functional improvements across all these patients correlated as they are with robust restoration of missing full-length protein in this monogenic and life-limiting, often life-ending disease. As Dr. Rodino-Klapac noted previously, we do believe it has the potential read-through to the rest of our limb-girdle portfolio. It's further confirmation of our DMD microdystrophin approach, and it is another important step in our strategy to build an enduring gene therapy engine that can expeditiously develop therapies to treat serious rare diseases, including these neuromuscular diseases. As I've said during the call and answered the questions, we will provide a further update next year on our development plans across our entire limb-girdle pipeline and portfolio. With that, have a good day, everyone.
Ladies and gentlemen, thank you for participating in today's conference. This does conclude the program. You may all disconnect. Everyone, have a wonderful day.