Avidity Biosciences, Inc. (RNAM) Earnings Call Transcript & Summary

Hello, everyone. I'm Kat Gallagher, Senior Vice President of Communications and Investor Relations at Avidity. Thank you so much for joining us today. Before we get started, we want to remind everyone that we will be making forward-looking statements based on the current expectations that are subject to and covered by the safe harbor protections provided under the Private Securities Litigation Reform Act of 1995 based on current expectations, including statements about the initiation of clinical trials. These forward-looking statements are not a guarantee of performance, and Avidity's actual results may differ materially from these forward-looking statements as a result of various important factors, including the risks and uncertainties related to the company's business. As discussed in the Risk Factors sections of Avidity 's SEC filings, including our recently filed 10-Q and 10-K. These statements are time-sensitive and represent Avidity's views as of today's date, and we disclaim any obligation to update these forward-looking statements following this presentation, except as required by law. Now this is the first in a series of investor and analyst events that we plan to hold this year. Welcome to Volume 1, where we'll be focusing on engineering AOCs. There will be a Q&A session at the end of the call today. So please feel free to submit questions to us at any time throughout the presentation. [Operator Instructions] With that, I'm going to hand the call over to Sarah Boyce, Avidity's President and CEO.

Thank you so much, Kat, and good morning and afternoon to everyone who's joining us on this call, which as Kat said, is the first of a series of webcast focusing on our whole journey as a company. One of the things, just to remind everyone, our vision and our goal is to be able to profoundly impact people's lives by what we believe is going to be a revolution in the delivery of RNA therapeutics through our technology, the Antibody Oligonucleotide Conjugates. One aspect in terms of looking at delivering on that vision -- there's a couple of elements. Firstly, if we look at platform, one of the things that we have done and developed entirely in-house with Art Levin and his team is develop what we believe is a new class of therapeutics, the Antibody Oligonucleotide Conjugates, and we've demonstrated preclinical proof of mechanism in multiple different tissue types. We're looking to broaden through other tissues and cell types as well through partnership and discovery. One of the first places we directed our technology was looking at muscle. We have a large pipeline, targeting a range of different muscle diseases. The first of those, AOC 1001 is set to enter the clinic in the second half of this year, which is hugely exciting for us as a company and also for the patient -- for the myotonic dystrophy patient community. In addition, we're also planning to initiate 2 clinical programs next year, AOC 1044 in DMD and our FHSD (sic) [ FSHD ] program as well. We're doing a lot of company building, as you would expect, and we firmly believe that people build companies. So we're very much focused on bringing in people with real deep experience in a broad range of areas, but in particular, rare disease and RNA therapeutics. Now taking a little bit of a broader look at our pipeline. And one of the things that I did talk about this morning, and hopefully those of you who are paying close attention, whether we actually now have selected our lead candidate, so we now have a candidate that we're entering into IND-enabling talks for DMD, and that is targeting Exon 44. So it's aptly and hopefully, somewhat appropriately named AOC 1044. And we're looking forward to entering the clinic the next year along with FHSD (sic - FSHD). And also we'll spend time today talking about AOC 1001, what we plan to initiate -- the Phase I/II study in the second half of this year. So in terms of moving from pipeline, and I started broad then onto pipeline. So let's focus specifically on the goals for today. Firstly, this is an opportunity to really provide a deep dive for the first time of the years of engineering that have been completed here at Avidity to support our AOC platform. We're also looking at how that platform then pulls through in relation to our pipeline. And we're also really looking forward to the panel discussion where we're getting into also offering a broader perspective on the history as well as the future of RNA therapeutics. For those of you who know us well, you know that we love engaging in discussion. We love talking about our science, our company, our technology. So very much looking forward to taking your questions as well as we go through today. So in terms of specifically looking at the highlights and what's new. So the first aspect is a deep dive on the AOC platform. We actually haven't done this to the depth that we're doing today before. It does 2 things. One, really demonstrates that data-driven approach and that aspect of following the data that took us through to the engineering of the technology as well as showing some previously unseen data that we will also use in specifically to choose the use of the monoclonal antibody. We're also going to look at AOC 1001 and the safety profile as we enter into the clinic. First is sharing additional non-GLP Tox data as well as really excitingly presenting the outcomes and data from our GLP Tox Studies as well. And then the third area around what new is really announcing that movement and progress with our pipeline, in particular, the naming of AOC 1044, which is now entering into IND-enabling talks. So looking towards the agenda for today. I'm going to be handing over to Art in a minute or so, who's going to go through the engineering and really looking towards the future of RNA therapeutics as well. We then have a panel looking at translating RNA research actually into medicines where we're delighted to be joined by 2 esteemed guests, Doctors Steven Dowdy and Phil Zamore, who are both experts with deep experience in the RNA space. We'll also do a Q&A session as well as part of that panel. And then also, I'll wrap up at the end with closing remarks. So moving to introducing our speakers. First off is Mike Flanagan. So Mike Flanagan is going to be facilitating the panel discussion. Mike joined us at the beginning of the year. He brings with him both deep expertise in the RNA space, in the antibody space as well as in the ADC space as well. We're thrilled to have Mike Flanagan join our company. The next key speaker, who I think needs no introduction, is Art Levin. Art is one of the leading experts in the RNA space and has really dedicated his career to bringing RNA medicines to patients. So with that, I'm going to hand over to Art, and we'll start to dive into the presentation. Art?

Thank you very much. Thank you for the kind introduction. And I would like to, first of all, thank the panelists for joining us today. And more importantly, I'd like to thank the folks in the audience who I wish I could see but can't. Unfortunately, that's not how this presentation works. But it's absolutely overwhelming the interest that we have today. And it's a great day when we can talk in-depth about the science. Earlier this week, we were talking about, am I excited about Science Day, and I had to laugh because in my world, every day is science day, I think. And so this is just a great opportunity to demonstrate where we came from and where we're going. So my talk is going to be broken up into 3 bits. The first will be a bit of a concentration on how we got to where we are, a little bit of our history. Some of the fundamental experiments that we did as we engineer this technology. Following that, we'll -- I'll show you how that engineering has been applied to our first clinical program, AOC 1001 for the treatment of myotonic dystrophy disease for which there are no currently approved therapies. And then finally, we'll talk a little bit more about the pipeline and then where we're moving from there to actually broaden out the platform where our AOC technology is broader than just skeletal muscle programs. And I'd like to talk a little bit about that going forward. So the company started years ago, and we were founded to use monoclonal antibodies to deliver oligonucleotides because the key issue in oligo therapeutics, of course, is delivery. And so at that point in time, we were using a nanoparticle formation. And in the process of engineering that nanoparticle formulation, we actually realized that -- and we were using a nanoparticle preparation that was decorated with the monoclonal antibodies in order to target our nanoparticles. As we engineered those particles, we realized that we're actually getting more effective delivery with the antibody oligonucleotide conjugate alone rather than the nanoparticle. So the company pivoted, again, based on data, to really become focused on using these direct conjugates. We reasoned, at the time, that taking advantage of the information that was available to us from the antibody -- sorry, the oligonucleotide conjugates that were being used in the liver. We realized that there were provisional transporters that could be exploited to deliver oligonucleotides into cells. And so we began a search, came up with a transferrin receptor, which was an obvious choice because the transferrin receptor is highly expressed and is quite active as a provisional transporter. And we began to develop a technology around that particular antibody. Note that this is pretty much different than the way other companies have developed oligonucleotides in the past. In the past, people have fallen in love with a particular molecular target, and they said, "Well, we cannot -- we can modulate that molecular target easily with an oligonucleotide therapeutic or with CRISPR or Cas and not realizing that mechanisms are great, but you really you have to get the oligonucleotide into the cell. And so we started from the opposite end of the spectrum. We said we can deliver oligonucleotides, and we found that we can deliver oligonucleotides well to muscle. And then we built a pipeline on that. And similarly, we're going down -- we're now exploring other monoclonal antibody cell surface pairs, each one of which may have the potential to build kind of a vertical platform -- vertical pipeline as we identify new receptors that we can use. So the problem, and I'm likely paraphrasing Steve Dowdy, one of our panelists today. The problem is that there are eons of evolutionary progress, which have made cells impermeable to external genetic material. So cells have evolved to actually keep out external genetic material. And when that goes awry, that's pretty disastrous. As we have learned in the past 15 months, and that's why we're all on Zoom today and not in a posh hotel ballroom somewhere in Boston or New York. Moving the genetic material, the genomic material for a virus, in this case COVID-19, has led to a worldwide pandemic. So when those barriers break down and the barriers to keeping genetic material out of cells break down, there's considerable trouble. So sales -- we've had to figure a way to get around that. And again, looking at nature, nature has used receptor-mediated uptake in order to facilitate the movement of various entities into cells. And so again, using receptor-mediated uptake here, we are taking advantage of the fact that cells can internalize our monoclonal antibody oligo conjugate. That oligo conjugate then binds -- is then degraded. The antibody is degraded, and the oligonucleotide can be released. So with monoclonal antibodies specifically, we can take advantage of their specificity, we can take advantage of their high affinity, and we can actually direct them to cells. Avidity didn't start out necessarily focused on monoclonal antibodies. In fact, we tried small molecule ligands in some of our programs. We tried peptide fragments in some of our early collaborations. But ultimately, we found that monoclonal antibodies performed the best and they have the greatest safety profile and the least technologic risk. Here's an example of a study that we did in nonhuman primates, where we compared an siRNA that was loaded onto a Fab fragment, we're looking at our plasma pharmacokinetics, versus an siRNA that was loaded onto a full-length monoclonal antibody. You can see quite clearly that the full-length monoclonal antibody has superior pharmacokinetics. So we optimized each of the components of our antibody. We started each of [ RP ] to the components of our AOC, starting with the antibody. So selection of the antibody was the first thing. We also selected the epitopes for this particular transferrin receptor that we built our muscle pipeline on, so it doesn't compete with endogenous transferrin. We've also made that, in particular, taking advantage of 30 years of monoclonal antibody engineering, we've been able to make that monoclonal antibody factor function null, so we're not going to induce ADCC. And we've also engineered where the monoclonal antibody is conjugated with the oligonucleotide. So each of these concepts was brought in for the initial step of, okay, let's select our targeting ligand. And in this case, we selected on the basis of data, letting data drive us to the monoclonal antibody, not small molecules, not peptides, not fragments. We've also engineered the linker. And then one of the things that I didn't make clear when we were talking about -- when I was talking about the fact that the company started out with nanoparticles, is that we brought in a number of bioengineers. And you know that bioengineers, of course, like to push systems. So this is an example where we pushed the system. We took a long-lived monoclonal antibody, injected it into the mouse and to which we've conjugated using 3 different linkers in siRNA. And what you can see here, there is remarkable differences in the -- again, the plasma circulation times of these oligonucleotides depending upon which linker was used. So this is -- when you're going to design a car and you want to test that car, you don't drive it around on suburban streets. You take it out onto the race course or you move it to the desert or you go to the Arctic and test it. This is kind of a worst-case scenario there. We took a very long-lived monoclonal antibody to which we then conjugated using different linkers. And we chose the one with the greatest selectivity. So we've engineered this specifically, maybe not for the transferrin receptor, which is actually relatively short monoclonal antibody of the transferrin receptor, which is actually relatively short-lived, one day half-life in certain species. But for the future, when we want to have a monoclonal antibody oligonucleotide conjugate there circulating for longer period -- periods of time. So we're using a noncleavable linker that is conjugated to our monoclonal antibody at the interchain disulfide bridges. Again, as we're moving through the AOC complex itself. So I talked about the optimization of the antibody, I talked a little bit about the optimization of the linker. One of the key pieces, and people have had tried making oligo antibody conjugates in the past. One of the key pieces that we really concentrated on was finding the right modification patterns. So what you're looking at here is an experiment that we did in the mouse, where we took different versions of a siRNA, in this case against myostatin. We made different chemical modifications to that, to that particular siRNA. And what you can see here is, depending upon the modification pattern, you can get very different behavior of this. Again, here we're looking at relative myostatin knockdown. You can see that in blue, we have a particular molecule that is long-lived, highly [ protin ] and long-lived. And so that modification patterns or modification-like patterns like those that we ultimately selected. So each one of these components was then, as I've told you, was optimized individually. And then, ultimately, how these molecules were arranged in space. So using our technology, we're taking advantage of decades worth of safety experience with the engineering of monoclonal antibodies and the fact that monoclonal antibodies provide very little technologic risk. Dozens of companies around the world know how to make monoclonal antibodies. Our linker is a linker that's been known and used before. It is highly stable, so that there's not going to be dose dumping when the drug is administered. We also know that that linker ultimately is irrelevant because the antibody is ultimately going to be degraded in the endosome life cell wall complex. And then finally, we modified the siRNA so that it could withstand lysosomal enzymes. And this is actually a key point because you'll see later on in my talk that our monoclonal antibody oligonucleotide conjugates are long -- have extraordinarily long-lived activity, which is great news for patients because it means that they can be dosed [ relative ]. We foresee them being dosed relatively infrequently in clinical and clinical usage. To get to the place where we had all of these engineering bits aligned, we did a lot of studies. We spent a lot of time doing studies in nonhuman primates. We use nonhuman primates specifically because they're going to have more direct readout to clinical trials. So you can see that very early on, we were looking at our delivery moiety. Should we be using the Fab fragment? Should we be using [ siRNA ]? Should we be using a mAb? Should we be using a full-length monoclonal antibody? Ultimately, for the reasons that I showed you and for reasons of the known safety profile of full-length monoclonal antibodies, we landed there. We did studies that would -- that allowed us to select a lead monoclonal antibody. We did studies in non-human primates that allowed us to actually select a lead siRNA and its modification pattern. And then we did an extraordinary study, what we're calling NHP Study 6, where we did an extensive pharmacokinetic analysis of the pharmacokinetic-pharmacodynamic interactions, and I'll show you those data in a few slides from now. And then finally, of course, the news for the day is that we've recently completed our GLP Tox Studies, and we'll now present the data from the primate studies. Spoiler alert, we're talking about -- the data are extraordinarily favorable to moving forward in the clinic. So while we're talking about moving [ charge ] to the clinic, our first drug, AOC 1001, really embodies a number of the key characteristics that I've tried to outline for you in the past few minutes. So talking about myotonic dystrophy. Of course, this is an irreversible disease at this point in time. It's not being -- there are no currently available therapies for these patients. These patients suffer from a mutation in a gene called DMPK. The mutation in this case, causes an expansion of a triple nucleotide, CUGs. Unlike other triple nucleotide repeat diseases, this does not ultimately result to -- the expansion of CUGs and the DMPK gene does not result in a toxic protein. It's the RNA itself that's toxic. And the manifestations of this disease are there a number of changes in skeletal muscle, cardiac muscle, respiration and in the GI tract, each of which can be explained on the basis of the following mechanism. The myotonic dystrophy -- the DMPK gene has these excess CUGs in them. Those excess CUGs in normal patients or normal people have 30 or less CUG repeats in their DMPK gene. Patients with the disease or people with the disease can have thousands of copies of CUG. Those CUGs form a hairpin loop. They're self-complementary. So Cs will bind to Gs on the other side of that hairpin. And this -- these high concentrations of CUGs that are associated with this messenger RNA attract a CUG binding protein, called muscleblind-like protein, here abbreviated MBNL. And if MBNL is inappropriately sequestered binding to these CUG repeats, it can't perform its downstream function and the downstream function of MBNL is to be a splice factor for other genes. So if all the MBNL is being sequestered in these large hairpin loops, the muscleblind-like protein is not going to be performing its normal function and the downstream genes that are normally processed by muscleblind-like protein are misprocessed. And so it is just actually the misprocessing of those messenger RNAs associated with other gene products that are responsible for the characteristics of the disease, the electrophysiologic changes that are associated with the characteristic myotonia where patients can't relax the muscle. And that's related to the fact that there's a chloride channel misplaced. There are cardiac conduction defects, which are probably related to either a chloride channel or the fact that there's also a calcium channel that's misplaced. Patients with myotonic dystrophy have an inappropriately spliced insulin receptor. So each of the manifestations of the disease can actually be explained by the mis-splicing of a number of proteins that have been -- mis-splicing a number of RNAs and ultimately, misprocessing of proteins. And of course, those can serve ultimately as biomarkers since we know what the downstream effects of muscleblind sequestration. The key here is that if you can reduce the number of CUGs in the nucleus, you can then reduce that sequestration of muscleblind-like protein, and you'll get normalization of the splicing patterns. And data to that effect have already been generated in a clinical trial that, unfortunately for the patients, was stopped because they were reaching -- with an oligonucleotide, were reaching levels of the drug which were potentially toxic. So in order to produce the pharmacologic effect that we're interested in here, you need to knock down the expression of DMPK, and we are interested in the concept of -- because DMPK is normally localized in the disease -- sorry, it's normally localized 50% in the cytoplasm and 50% in the nucleus. In the disease state, where there are all the extra CUGs, there's a significant fraction of the DMPK messenger RNA, which is trapped in the nucleus. So what I'm showing you here are data that demonstrate that our lead siRNA can knock down the -- both the cytoplasmic fraction of DMPK as well as the nuclear fraction. These are data that were produced by a -- sorry, that were collected from a DM1 patient, a patient with thousands of CUG repeats. And here, you can see quite clearly that we can knock down the expression of DMPK in the nucleus. If you knock down DMPK in the nucleus, you're going to see reduction in nuclear foci, and the next slide shows that quite nicely. So what you're looking at here, in the top panel on the left-hand side is encircled, are muscle cells, in which you can clearly see that the nuclear foci are present. When treated, you can see that the nuclear foci are missing. And on the left -- sorry, on the right-hand side, what you can see, in fact, is that we have a -- we've essentially saturated the pharmacology here, even a 1 nanomolar concentration of our siRNA is producing greater than a 50% reduction in the number of nuclear foci, all of which is very encouraging. I would also point out the fact that these are drugs that are active at the nanomolar range, which I think -- which I'll emphasize more coming up in the next few slides. So reducing foci are important. That's -- it's clearly something that you can visualize under a microscope, that's nice. But the real goal here is to change the ways that cells are splicing key genes. So in this particular experiment, I want you to compare the untreated cells, shown as the black diamonds on the right-hand side, with cells that have been treated with -- sorry, myotubes which have been treated with our lead siRNA. And here you can see that there's a 56% increase in the splicing index. This is a 100 -- unbiased selection of 100 different splicing events. And you can see that we moved the splicing pattern up about 56%, more towards the normal pattern, which is shown in either the blue circles or the black filled diamonds. So again, the key component here is the fact that we are producing a reduction in the gene expression of DMPK. We're reducing the number of nuclear foci. We're getting the kinds of splicing changes that you want in order to produce pharmacologic activity. This is all important, but now let's see what happens in vivo. So in vivo, these are some data in normal nonhuman primates. These nonhuman primates have been treated with a single dose of 2 milligrams per kilogram, gave this by intravenous administration. The dose is 2 milligrams per kilogram of the active siRNA or about 20 milligrams per kilogram of the total dose. And what you can see here is that there's greater than a 75% knockdown that lasts through to 12 weeks. Single dose 12 weeks at least worth of activity. Now there's no magic here. We understand quite well why we had such long-lived activity. Again, recall that I've mentioned that we've stabilized our siRNA preparations so that they are stable within the endosomal-lysosomal complex. And so the endosome actually works in our favor here. It works as a controlled release depot, allowing our oligonucleotide to pay out over time and continually loading the RNA inducible silencing complex. So by loading risk, we're going to maintain activity for long periods of time. And on the next slide, I'll show you a dose response curve that we did again, in nonhuman primates, single dose of 1 milligram, 2.5 or 5 milligrams per kilogram, reduces greater than 50 -- excuse me, greater than a 50% reduction in the expression of the key target gene here, DMPK, and again, it lasts for a long time. More importantly, note that our ED 50 here is less than 1 milligram per kilogram. And these are data that were taken at week 6. So again, long-lived activity, we're getting activity in the tissue types and cell types that are required in order to help these patients. We know their cardiac conduction defects. The previous slide showed you knockdown in skeletal muscle. And here, we also show the change in gene expression in the diaphragm. These are key areas for the patients with this disease in areas where we want to make sure that we have great activity. On the right-hand side, you can see, again, much like the skeletal muscle that data that I showed you on the previous slide, we have long-lived activity. So at single dose of 2 milligrams per kilogram still produces greater than 50% knockdown in the heart and almost 70% knockdown in the diaphragm. We think, although there is no -- there are no strong data to actually create a firm threshold, we believe that knocking down the toxic mRNA DMPK for greater than 50% is probably going to be required for activity. And those are -- and we will be treating -- we will be attempting to knock down gene expression to that degree in future clinical trials. The next slide shows that we get broad -- we get knockdown of gene expression in multiple muscle biopsies for multiple cell types. And here, at single dose of 6 milligrams per kilogram, 4 weeks after administration, you can see that there's greater than 80% knockdown of DMPK. Below each of the bars, what you can see is the tissue concentration in nanomolar. So when compared to data that had been generated previously and published or presented using an antisense construct, they were attempting to achieve micromolar concentrations, and these are data from clinical trials that has been reported by others. The tissue concentrations where we're getting activity are in nanomolar range. So clearly, there is extraordinary activity of an siRNA therapeutic to knock down gene expression across a broad range of muscles that are shown here, including muscles -- including organs or tissues, which are potentially enriched in smooth muscle, as is shown by the data from the jejunum and the ileum on the far right-hand side of this slide. As we were studying AC 1001, we did a pharmacokinetic, pharmacodynamic study, which also served as our non GLP Tox Study. And as you can see here, we did extensive plasma pharmacokinetic analyses. What's interesting about this particular slide is that with repeated administration of our AOC 1001, you get similar peak concentrations over time. You get similar trough concentrations from injection 1 to injection 2 and the slopes of the lines are similar for each of the dose groups going from injection 1 to injection 2 to injection 3. This indicates that there are no neutralizing antibodies to our AOC 1001 in the nonhuman primate. Why is that good news? It's good news because we're actually giving a human protein to a monkey and not seeing a large immune response, which is indicative of the fact that we've done a good job at designing our monoclonal antibody and designing our AOC, so that it's not inducing a significant immune response, which is going to change either the pharmacokinetics or the pharmacodynamics. Note that the plasma half-life for this particular construct is about 1 day in non-human primates. And it is slightly dose related. We might expect that this half-life will be a little bit longer in humans, but not significantly. So that's -- at this point in time, of course, speculation since we have yet to do the studies. The key point here is that even though we're giving a human protein to a monkey, we're not seeing neutralizing antibodies, which was really something that allowed us to rest easier because, of course, this was part of -- this was one of the unknowns we had moving forward. Is this construct going to have some sort of new immunogenic potential? And so far, and again, that's what you have to do before you get to a clinical trial. So far, the data suggests that that's not the case. The pharmacokinetics, as you saw, the plasma pharmacokinetics, as you saw on the last slide, were almost textbook. Beautiful first order kinetics. What you can see on the left-hand side is that we also have beautiful tissue kinetics. So what you're looking at on the left-hand side of this particular graph is that we have a concentration versus dose plot. And you can see that we have linear accumulation in skeletal muscle, depending upon dose. The right-hand side is -- really is a nice demonstration of the fact that we -- that just how good these kinetics are and just how thorough our analyses have been, and the kinds of data that we are giving to our clinicians as they're designing their first clinical trial. What you can see in the far right are the number of different dose groups that are represented in this particular study. You can see, again, a broad range of doses that we're using here. And what you're seeing on the right-hand side of this slide is the reduction in DMPK expression versus tissue concentration. And if you look at day 21 or day 28 post dosing, the effective concentration that produces 50% knockdown is less than 1/10 of a nanomolar. So again, we have a highly active siRNA that we can deliver effectively across a broad range of skeletal muscles, as I showed you a couple of slides ago. And these are the kinds of concentrations that are easily achievable in clinical trials with doses below which -- that we've already presented here. So the big reveal for the day is -- are the non -- or the GLP tox studies. And of course, the GLP tox studies are a key component of any investigation on new drug application or any CTA, and we're really quite proud of the data that have been generated, and I think you'll be impressed by the data as well. We saw no dose-limiting toxicities that were observed in the monkeys at the highest dose tested. We saw no changes in platelets or renal toxicity that are going to [ subphase ] with other oligonucleotide therapeutics in the past. There were no treatment-related changes in histopathology, no other changes in hematology, clinically adverse effects in hematology or serum biochemistry. We also looked at safety parameters, safety parameters such as cardiac, respiratory and neurologic changes, all of those were uniformly negative. The NOAELs -- no adverse effect levels, were the highest doses tested in the monkey. And as I'll show you on the next slide, the pharmacology was essentially saturated. We had similar results in the mouse and, of course, we think that the nonhuman primate is the most relevant, and that's what we'll concentrate on today. So this slide shows the reduction in gene expression of DMPK in our GLP tox studies. And what you can see here is that across a broad range of skeletal muscles, gastrocnemius, latissimus dorsi, vastus lateralis, diaphragm, intercostal muscles, left ventricle. In skeletal muscles, we're seeing almost 80% or 90% knockdown of gene expression that was essentially saturated across the doses that we used in this study. You see significant knockdown, greater than 75% knockdown in the left ventricle. So again, we -- the key point on this slide and the point that I want you to take-home with respect to our non-GLP -- our GLP tox studies, excuse me, is that there were no effects -- no adverse effects associated with the reduction of DMPK and no adverse effects associated with the administration of the transferrin-based AOC, AOC 1001. So again, outstanding pharmacology, essentially saturated pharmacology in most tissues and yet no adverse effects associated with these high dose exposures. These exposures are many-fold higher than the doses that are intended to be used in the clinic. So we're ready to move into clinical trials. Our planned Phase I/Phase II study is to initiate in the second half of this year. That's going to be -- that's based upon the fact that we can deliver this particular RNA therapeutic in a highly effective way. We get reductions in the key genes that we're interested in. Our EC50s are in the nanomolar or sub nanomolar range. We have activity weeks after administration of -- or even months after administration of a single dose. We have a favorable safety profile. And we have a safety profile, which also includes the fact that reductions in gene expressions are primarily localized to the key target tissues of interest. And finally, we recently received a patent for AOC 1001. So we're moving towards clinical trials with significant wind at our backs, and we're highly encouraged by the characteristics of this particular AOC. And we think this particular AOC bodes well and serves as a model for other AOCs that we'll be putting into clinical trials soon, and that brings up the concept of our pipeline. And so we're building upon our experience with AOC 1001. Of course, AOC 1001 has now completed IND-enabling studies. We're getting ready to move -- or we're moving our next clinical program, each building on the same transferrin monoclonal antibody into clinical trials, or into IND-enabling and then ultimately, clinical trials. So 2 programs that are moving forward in near parallel at this point in time. Our FSHD program, which is targeting a gene called DUX4, which is inappropriately expressed in patients with FSHD. And we have got a program in Exon skipping, where we can take advantage of our AOC technology to deliver a single-stranded morpholino oligonucleotide that's designed to skip particular exons in the dystrophin gene. In this case, Exon 44 suitable boys or treatable boys, and that compound is moving into GLP tox at this point in time. We also build on a number of other programs in Duchenne muscular dystrophy. Of course, this is a disease that is currently underserved. We think that our program offers significant advantages over some of the existing programs out there and the ability to use our monoclonal antibody platform to build a whole armamentarium in muscular dystrophy alone is extraordinarily useful. In addition, we've got programs in muscle atrophy and in Pompe disease, all of which are building upon the knowledge that we've gained from AOC 1001. The FSHD program is a really good example of how we could actually accelerate a program. Once we had the appropriate experience developing AOC 1001 it was relatively -- I don't want to make it sound too easy because the team worked all summer very long and under pandemic conditions, but it was relatively easy to identify an active molecule and then create not just the active siRNA, but then create the active AOC, the complete conjugate. So again, we are incredibly enthusiastic about the ability of us to build this pipeline based upon our existing experience with AOC 1001, allowing us to continue to move compounds into formal development and then ultimately, clinical development. In addition, the technology for antibody oligo conjugates is more broadly applicable. We know that there are other targets in the liver besides hepatic parenchymal cells, and you can find other monoclonal antibody receptor pairs that can perhaps target other cell types in the liver. We are looking currently with -- in a collaboration with Bristol-Myers and MyoKardia at delivery of oligonucleotides to the heart. I've already shown you data today that demonstrates that we have activity of our oligonucleotide therapeutics in cardiac muscle. We have data that support activity of our AOC technology in immunology in a collaboration with Eli Lilly, that's where Lilly has a defined number of targets in the immunology space and other diseases that are, in fact, allowing us to broaden our technology into immunology as well as having access to a library of monoclonal antibodies for a particular target step-up that Lilly is interested in. We get a lot to -- what we've done strategically is we're getting a lot of experience by interacting with these companies who are area experts in the particular areas that they're working in. And then finally, we have programs in-house, both in immunology and in immuno-oncology that are, again, taking advantage of our ability to find cell surface receptors and monoclonal antibodies to those cell surface receptors that can effectively deliver oligonucleotide therapeutics in order to get the appropriate activity of an oligo therapeutic. So the dream of oligonucleotide therapeutics has always been to be able to take advantage of Watson and Crick base sharing in order to rationally design therapeutic agents based upon genomic information. The problem has always been that if we were unable to deliver on that dream because we couldn't get the oligonucleotide therapeutic to the cell or tissue of interest. With our AOC technologies, we are taking advantage of, in this case, monoclonal antibodies to find new cell surface receptors or take advantage of cell surface receptors that are internalized, that will bring our oligonucleotide therapeutic into the cell. It's the result of years of engineering that we performed on this platform. And it's really taking advantage of the safety profile of full-length monoclonal antibodies and the safety profile of siRNAs that's really allowing us to build not just a muscle pipeline but potentially other pipelines in other therapeutic areas. And that's really the goal for the company. We want to treat patients with rare skeletal muscle diseases, but we also want to make sure that we can offer treatments to other patients with other diseases and other cell types where oligonucleotide therapeutics have an appropriate role, but where we've been unable to deliver them. So again, we've shown you data from -- in the general case, and we've also shown you data in the specific case of AOC 1001. We're poised to begin our Phase I/Phase II studies in the second half of this year. We have an expanding pipeline, as you've said, and certain -- as you've seen, and we certainly have the potential to administer AOCs for a number of different disease indications that are outside of liver, outside of skeletal muscle and in other tissues. And for today, we're focused on our newly declared candidate for -- in Exon skipping, for Exon 44, and the acceleration of our FSHD program into IND-enabling studies. But we have our focus on rare diseases and moving forward from that, of course, we have the potential to deliver oligonucleotide therapeutics for -- across a broad range of indications. So the technology has both a really nice vertical component with respect to our ability to have developed a pipeline of rare muscle diseases, but we also have the ability to develop other vertical pipelines with other -- in other therapeutic areas. And I think that's really where we would like to go with this technology in the future. So with that, I'm going to turn it over to Mike Flanagan, and Mike can introduce the panel speakers.

Thank you, Art, for sharing how we've followed the data to deliver RNAs to rare muscle diseases and beyond. I'm really happy to have our panel discussion today, delighted to have 2 accomplished RNA experts to continue the discussion of translating RNA research into medicines. Let me first introduce Doctors Phil Zamore and Steve Dowdy. Dr. Phil Zamore is a Gretchen Stone Cook Professor of Biomedical Sciences and Professor of Biochemistry and Molecular Pharmacology at UMass. Dr. Zamore is a Howard Hughes Medical Institute investigator and chair of the RNA Therapeutics Institute at UMass. Dr. Zamore is a leading expert in RNA-targeted therapeutics and has been associated with leading companies in the field. Phil received his AB and PhD in biochemistry and molecular biology from Harvard and then pursued post-doctoral studies at MIT and the Whitehead Institute. Thank you for joining us, Phil. Dr. Steve Dowdy is a professor in the Department of Cellular and Molecular Medicine at UC San Diego School of Medicine. Dr. Dowdy's research focuses on the delivery of novel therapeutics, especially RNAi, into cells and tissues. Dr. Dowdy has been involved in multiple RNA biotech start-ups and currently sits on 5 scientific advisory Boards. Steve received his PhD in molecular genetics from the University of California Irvine. Go Anteaters. And performed his post-doctoral fellowship at MIT and Whitehead. Welcome, Steve. And let's get started. So you liked the go Anteaters comment, Steve? So we have [indiscernible] we've had enormous advances around RNA therapeutics in the last decade. And both of you have played key roles in these advances. Let's start with Phil first. Phil, what do you think has been the single most important development in delivering RNA therapeutics beyond the liver?

Beyond the liver, I would say, delivery to the CNS by redesigning what we think of as siRNAs to have either different conjugates or to be dimers.

And Steve, thoughts?

Yes. I think the ability to go beyond the liver has really -- is really because of the chemistry that was developed with the GalNAc conjugates to the liver to understand what we needed to do in order to get conjugates to work and the metabolic stability. So it's really the chemistry that's been applied to the siRNA with that incredible up to 6-month stability inside of the endosome of the target tissues.

Yes. I totally agree with that. That stabilizing chemistry has turned what people thought was a huge weakness into an unexpected strength that makes these among the most durable oligonucleotides to date.

Yes. I think you can see that demonstrated in the data that we presented today, where a single dose of oligonucleotide, in this case, in a skeletal muscle that previously -- a tissue that previously was untargetable or undruggable with oligonucleotide therapeutics, where we have at least 12 weeks of activity after a single administration. I think that really speaks well to the fact that you can take advantage of the fact that there are internal depots of drug that are going to slowly pay out the drug over time, whether that's in the CNS, where, of course, there's long-lived activity or where that's in muscle or potentially other tissues. So I know Steve used that as a weakness.

[ Hysterical ] You're paraphrasing.

On the other hand, yes, we can actually take advantage of those long-lived depots. And that's how you get such remarkable activity, like I showed earlier, where a single dose produces activity for 12 weeks or even part even, as you saw.

The depot effect where the drug, the RNA, stays inside of the endosome is clearly a huge advantage. Again, because of the metabolic stability, the enzymes just aren't available in [ ELISA's ] overlay. Endosomes chew these up and degrade them. And so that gives you opportunity for this very slow, continuous release. We can just work in the future to enhance that, so we can tackle things like oncology, which is really [ untackleable ] today because of the rapid turnover of the cells and trying to get it delivered to all of those cells, for instance, too. But I think when you look at the RNA therapeutic chemistry today versus 10 years ago, it's black and white. It's absolutely night and day. You can't pull any of the data that we learned 10 years ago about [Technical Difficulty] it to drugs. None of that is relevant. So anything that you -- the audience may have heard 5, 10 years ago, these are unstable, they can't be delivered, all these sort of things. Yes, that is simply not true today. It's proven in human clinical trials, approved RNA drugs of ASOs and siRNAs. And so this is a brave new world of an amazing molecule. Can you imagine a drug you take once every 3 months or once every 6 months and perhaps in the future, as we continue to optimize the chemistry and the knowledge of delivery, maybe once a year. It's amazing. It's absolutely amazing.

Yes. If you look at the first lipid nanoparticle siRNA drug, ONPATTRO, right, that's 3-week dosing. And here we are looking toward widespread use, hopefully, of drugs that have semi-yearly dosing, it really totally changes the landscape of compliance issues. Patients will be taking their drugs without fail. I mean you're talking about just an effort to get the drug twice a year.

An add-on to that, too, is it doesn't stop at 3 months. So Art's knockdown doesn't stop -- or Avidity's knockdown doesn't stop at 3 months. It keeps going on and on so the patient doesn't have to show up at 3 months plus 1 day, otherwise all the therapeutic benefit is going to be thrown out. It can drag on longer than that. And so the patient has some flexibility to come in this week or next week to get their next dosing. It's not an absolute got to take it this morning, every morning, kind of a thing in order for it to work. Just an amazing, broad new world of medicine.

Yes. I mean, it is one of those things that is just -- even a few years ago, just -- you couldn't imagine just being able to dose so infrequently, especially for diseases in children where -- do you really want to take them out of soccer practice and go to the doctor and those kind of things, right? I mean we've all been there where you're doing sports and you're traveling and all those kind of things, where you may not be close to your doctor. So it's really beneficial for patients, I think. So the -- one other thing is that kind of thinking about this brave new world. We're constantly learning about new roles of RNA in biology. And it really -- we could argue about it, but it really truly is an RNA world. And I think one of the things, and maybe, Steve, I'll have you start on this, is that what role do you think oligonucleotides in general, and maybe conjugates and AOCS, in particular, could play in modulating these newly identified RNA functions?

Yes. Just to go back a little bit, like 3 billion years, it really was a primordial RNA world that then became encapsulated in the first lipid bilayer that essentially was the first living cell. And RNA then allowed the development or drove the development of DNA for more stable storage of genetic information, but we have to go back to the world and all the defenses that the cell has is based on RNA. So we exude RNases from our fingers. Our cell phones are covered in RNases. Everything we touch is covered in RNases because it was an RNA-centric world. And unfortunately, when we all went through graduate school, we were taught the standard -- central dogma of DNA to RNA to protein and then RNA can be converted back into DNA with reverse transcriptase, that it really is this RNA-centric world. And when you look at the regulatory mechanisms of RNA interference, PIWI RNAs, other regulatory RNAs, lincRNAs. It's just amazing how much RNA is central to life on this planet. And as we discover more and more of these RNA pathways, what better drug than an RNA that can base pair to that specific RNA. And that's the beauty of these precision genetic medicines is they're going after the root cause of the disorder, which is the RNA. And other small molecules just don't have the size of information embedded in them to specifically go after an RNA like we can get due to base pairing. And so we're -- this RNA therapeutic world is really set up as the next level of regulatory RNAs become discovered and shown to be involved in human disease, we can rapidly jump onto those with these RNA therapeutics.

I think the other thing that makes RNA drugs special is that the delivery modality and the targeting modality are discrete modules that can be shuffled. So if you have an siRNA that you know works against a target in liver with a GalNAc conjugate, that same siRNA can be delivered as an AOC to a muscle disease. You can take the same delivery method that's been demonstrated by nonhuman primate's [ inhibitidy ] and swap out the siRNA for a different target. And so these have truly become modular informational platforms where we're finally taking advantage of all of this genomic sequence and transcriptome profiling to design both the targeting moiety and to design the drug itself.

Mike, just to go even sort of further on the development of RNA therapeutics, not only can we go after every individual RNA because of the base pairing, but manufacturing from a CGMP manufacturing, the line that produces these is the same line for every molecule. Just as Phil said, all we're doing is changing the sequence of the RNAs and the targeting domain, in this case, the active site of the antibody. The rest of the processes are all the same. So we don't have to set up an entirely new line of manufacturing in these facilities. We just plug-in our particular sequence, plug-in whatever the targeting domain is, an antibody, and then, bam, the linkers and everything else is the same. So this modular approach really improves the overall efficiency of manufacturing and the consistency as well, too.

Yes. I mean, those are great points. I mean, I guess what I'm hearing from my point of view, I'm hearing like you guys are describing it as a platform. Where it's kind of you can plug different pieces and put different pieces together, depending on the disease and tissue type. Art, what are your thoughts about that?

And I think you're seeing the example of that here because we're going to move a lot faster on the second program, third program and fourth program than we -- than we did with the first. We did the engineering around the targeting moiety. In this case, the transferrin receptor. We understood that. And then obviously, it becomes -- I don't want to say, plug-and-play, but it's a lot more plug-and-play than developing a new small molecule every time. It allows us to take advantage of a delivery mechanism and then put on the appropriate therapeutic entity. So yes, it is extremely useful, and you can even see the fact that we could accelerate FSHD, our FSHD program faster than we thought because once we found an active moiety, an active sRNA, we then know how to perform the rest. So it is a little bit fortunately like Tinker Toys. I don't want to denigrate all the hard work that our chemists are doing and that our biologists have to do to make sure that we have the tinkertoy effect. But the -- in reality, we are getting significant synergies from one program to the next, which, of course, has always been the dream, the concept.

Yes. It's really impressive, Art. For those of you in the audience, Avidity is head and shoulders above any other group or company for making antibody oligo conjugate. So -- and the ability then to just plug and play. I don't think you're being excessive in saying that, Art, because I think it's really on the verge of being really straightforward in that sense.

Thank you. I can assure you the team -- thank you. Hopefully, the team is going to hear this, but they've been working hard to make it look plug and play.

And if you think about the way small molecule drugs are discovered, that's high throughput screening to identify a lead and then medicinal chemistry to make the lead a real drug, whereas you have the ability to spend all of that energy that you no longer have to spend on high-throughput screening on bringing a chain of incremental improvements to a great technology to make it better each pass, whereas you're not going back to the exact beginning again and searching for a new drug.

Yes. Great points. I think as we're talking about this and trying to think about how RNA Therapeutics fit into the broader landscape. We've had recent advances in technology. We talked a little about delivery, being able to deliver to different tissues. But we have gene editing on the horizon. We have gene therapies on the horizon that promise a single treatment for a lifelong effect. I think, Phil, maybe you can take this one. Kind of how do you see RNA therapies and sRNA in particular, kind of fitting into this future landscape of RNA therapeutics overall?

Well, the advantage of drugs over permanently modifying people's genomes is that you can alter dose, you can change the target, you can change the drug modality as people age as their condition develops as their diet or exercise changes. And so you have the ability to respond to the way the patient changes with time. With -- gene editing is premised on the idea that the defect is immutable relative to the person. And of course, we know that the interaction between the environment and genetics plays a huge role in the outcome of diseases. And so I think drugs will always have the advantage that you can stop them and change drugs. You can change doses. You can go to an improved therapeutic modality in a way that isn't possible with gene editing.

Yes. I think there's the notion of a hit and run approach with an RNA therapeutic, which is similar to small molecules and biologics as well, too. It's there when you want it to be there, and it's not there when you don't want it to be there, should there be an adverse effects or change in your overall physiology. And I think that the nonviral DNA therapeutics, the viral therapeutics, the editing. I think all of these will have places. I think the -- depending on what the disease is, the severity of the disease and the delivery of all of these agents to these specific disease cells, that it's going to dictate which modality you would use. And we're not going to do away with small molecules, for instance, either. So RNA therapeutics is not going to 100% displace small molecules or biologics. And likewise, permanent single dose modalities are also not going to replace RNAs or small molecules. I think there's plenty of unsolved human disease out there, unfortunately, and there's room for all of these modalities. And both the patients will decide what the risk they're willing to do and what they would like to take, whether they stick with statins or take an RNAi or be edited to solve hypercholesteremia, for instance. And there's 7 billion of us out here that need therapeutics for various diseases. So I think there's room for everybody. We're not even close to having things competitive against each other because there's so many untreatable diseases currently today.

And Art your thoughts?

Just building on what Steve was saying, with a multitude of untreatable diseases and now the ability of RNA therapeutics to come in and actually use rational drug design, design drugs based upon genomic information. That -- and then being able to deliver those tissues, that really will ultimately allow us to deliver on the promise of oligonucleotide therapeutics. We have all the genomic information. We know it. It's essentially digital. It's not binary information. It's quaternary information. But we have that information. And then with a little bit of empirical work, we all know that we have to do a gene walk at this point in time in order to find the right sequence, but with a little bit of work, you can find an active sequence relatively fast. I think that was the evidence for that is in our FSHD program. It could actually accelerate in the midst of a pandemic. And using that digital format that nature has given us, we can design -- rationally design drugs. And now if we can deliver them into a broad range of tissues, that really becomes a game changer for the way we think about disease. And that's always been a dream. Phil's got the Institute at UMass related to the dream.

Yes. And of course, most diseases are not genetic diseases. They're complex interactions among the level of mRNA expression in the patient. And so one can know the therapeutic target, even without understanding the underlying cause of the disease. So if you have high cholesterol, we know what to do, even if we don't really understand the complex genetic interactions that led you to have high cholesterol. And so for most diseases, it isn't even clear how you would use these more permanent nondrug approaches, the editing approaches because there isn't an obvious target.

Yes. The ability to target a disease gene without having to know its function or in structure, which is the case that you absolutely need to know those for small molecules, it's just really a paradigm-shifting approach. And it allows the power of genetics and DNA sequencing and RNAc to identify targets that RNA therapeutics can very rapidly jump on to. And going after FSHD, I have an MD -- PhD student in my lab, who has this disorder, and she's like, I can't believe if there's a company up the road that's going to start a clinical trial on this, and it's been hereditary in her father, her grandfather. So these are just -- it's really a brave new world. It's really a fantastic time in medicine to see these kind of things coming into clinical trials to help these patients that otherwise have absolutely no help with the prior modalities.

Yes. Yes, it is remarkable. So one of the things kind of we're thinking about this brave new world and kind of helping patients in a broad number of different diseases. Just wanted to think about, and this question might take a little bit of time because it's kind of a big future-looking question. But it took us like 30 years to deliver oligos beyond the liver. Like we're in the liver. If you have to pick an organ, liver is not bad. But you got to -- going beyond it, took us 30 years. So what is the next big dream? And how could it take us kind of 5 years rather than 30 years to kind of reach that next big dream for RNA therapeutics? And, Art, I don't want to leave you out. So Art, why don't you -- you can take a shot at the big dream picture first.

Yes. So the dream, and I think we've already -- we've already gotten to the dream to some extent. But the dream that I have and the dream that I really look forward to seeing come to fruition, is that we may have, at some point in the very near future, the ability to deliver oligonucleotide therapeutics to multiple cell and tissue types, perhaps have a library of monoclonal antibodies or library of bispecific antibodies that's going to allow us the specificity that we can use on the selectivity of targeting specific cells that we can use to deliver oligonucleotides therapeutics to a broad range of cell and tissue types so that we really do fulfill the promise that we've been talking about in the oligo space in my 25 years in the oligo space about this being another leg of the therapeutic stool, and that's so that we can really begin to utilize oligonucleotides therapeutics appropriately. And now with oligo therapeutics having such long pharmacologic activity, we really are talking about potential revolutions in a number of different areas. But my dream is having the ability -- having a library of delivery agents that's going to allow me to go to tissue X, Y or Z and target gene X, Y, Z. Again, this kind of the tinkertoy approach where we know how to -- we have our targeting ligand. We have our linker chemistry worked out. We then have our therapeutic. Pick your kits, pick your cell, pick your therapeutic target, link them together, off you go. It's my dream. I'd love to see it happen. I think we're very -- we're closer than we ever have been. And I think using the understanding that we're getting from this technology and perhaps developing other technologies like bispecifics for these kinds of approaches will really potentially revolutionize the way that we even think about oligonucleotide therapeutics, which is already a revolution.

I think for me, the prospect of siRNA drugs for CNS disorders will be fulfilled in 5 years. We began working on Huntington's within a few years of founding Alnylam. And to date, I think we're finally close enough that we'll see this in the clinic. However, the holy grail is to be able to deliver siRNAs intravenously to treat CNS disorders. And I think that is still a major challenge. Obviously, one is not going to deliver siRNAs to treat diseases where there are existing drugs, if you have to have direct administration to the CNS. That really raises the bar in terms of severity of disease and lack of options. So I'd love to see that develop.

So for me, we were -- before we started, we were talking about baseball. So I'm going to swing for the fences here. I'm a cancer biologist, and I would love in my lifetime to have patients go to the clinic, get biopsy, have their DNA of the tumor sequenced by mass spectrometry, which is instantly. And then the doctor says, "Oh, yes, you have KRAS 12 of LG mutation. So why don't you sit here, read a magazine, I just ordered your drug. It's sitting in a warehouse downtown. It will be here shortly by drone. I'll inject it into you. And you're going to come back in 3 months. We're going to do it all over again, see if any new tumors have any mutations have arise and if they have, we have all of these sitting on the shelf. And the model for this is when we order an siRNA today in a basic science laboratory from a reagent company, they don't make these siRNAs for us. They're already sitting on the shelf against KRAS, meG, every oncogene, every important regulatory gene, there's libraries of bedded, validated siRNAs, sitting in freezers on the shelf in reagent companies, and they show up the next day or 2 days later. I hope that model can be applied to not only oncology but to every or most human diseases. The one rate limiting, little tiny humongous problem is what's called endosomal escape. And this is part of the delivery problem. So these endosomes are like little vesicles like a stomach. It's like your stomach in your body and your food is sitting in there. And if the food can't get out of the stomach into your blood, it doesn't count. And for a cell, the stomach is this endosome. And the sRNA stand there, as we talked about earlier, as a depot, which is fantastic because it drips in, the sRNA slowly escape out of there. We just need to figure a way to enhance that maybe 5, tenfold would be fantastic and have control of it, and then we can really hit diseases like cancer, which because of the cellular division and the metabolics of the diseases are really difficult to treat. And if we can enhance that escape into the cytoplasm of the cell, this idea of being able to deliver to any tissue, any cell in the body with targeting domains just like Avidity has here. Yes, that's realizable in our lifetime. And it probably will happen sooner rather than later. The way this is really accelerating now. Again, because we're standing on the shoulder of the chemists that for 50 years solved every problem you're concerned about as an investor. The chemists have already solved that in the prior 50 years.

That was a -- I love the dream and the swinging for the fence. I love that. And specifically, the drones dropping off the silencing RNAs to clinics.

I was on the spot as I was thinking, right, you wouldn't use this -- by the time we can do this, you're not going to have a messenger on a bicycle doing this for you. It's going to be a drone.

Yes. That was awesome. So any kind of last things, Art, before we kind of wrap up the panel, on the dream?

I think we -- I don't -- I can't top Steve's dream and the drones and how that all works. No, I think -- look, I think that there is consensus that the dream is to have delivery systems that are reliable, that are cell specific and that can get the oligonucleotide therapeutics to where they need to get, whether that be the CNS, whether it be to tumor cells or tumor cells in a particular state or various cell and tissue types in other disease states. I think the dream is clear and similar amongst us. And I think it's a great place. And it really is a great place for us to open the questions up to more broadly to the audience and some of them will be directed at Avidity, and some of them will be directed at the experts that we have, but it really is a -- it really has been a pleasure to be part of this discussion. And I love the dreams. And yes, it is -- for those of us, Phil and Steve and I who have all really lived through the evolution of oligonucleotide therapeutics, it is nice to see when you make a jump to yet another system that works. So we made a jump from naked oligos or lipid nanoparticle oligos to conjugates and now we've got specific conjugates. So it's really -- it is gratifying and really fun and important in the field because we can now address more patients, and that's the key. Yes.

I'd like to just join Art in really thanking Steve and Phil for joining us on the panel. And I think some of your dreams are the same dreams that why I recently joined Avidity, right? The opportunity to create that broad delivery platform, discover RNA therapeutics really quickly and turn them into medicines and the opportunity to improve patients' lives. So all -- those were -- are my dreams also and the reason why I recently joined. So thanks to everyone. And I think, Art, you're going to be moderating questions from the audience.

I will be. And thanks, Mike, and thanks. Let's realize some of these dreams. So clearly, the audience hasn't held back of tough questions. The first one is…

Phil has a lot of answers. Fortunately, Phil has all the answers.

So this one is from Ritu at Cowen, and she's asking about the physiologic distribution of the -- sorry, let me welcome Sarah to the panel as well. Thank you, Sarah. Ritu is asking a question about the physiologic distribution of the transferrin receptor across organs and tissues. And I think I will take that one. And we do know that the transferrin receptor is ubiquitously distributed across a number of cell and tissue types. Interestingly, the liver has its own transferrin receptor, transferrin receptor 2, but the transferrin receptor 1 is ubiquitously localized or not localized. What we found in our studies, however, is that if you deliver an oligonucleotide, that's an siRNA, to a housekeeping gene that's conjugated to the transferrin receptor monoclonal antibody that the primary activity that we see is in striated muscle and to a lesser extent, smooth muscle. So we will see knockdown of our housekeeping gene, primarily only in cardiac, skeletal and, to a lesser extent, in smooth muscle. The data that we recently generated at toxicologically significant doses, demonstrates that there is a little bit more activity there than perhaps we had expected. But in general, the activity is not proportional to the expression of the transferrin receptor. It may be actually differences in tissue sensitivity are related to the way that the transferrin receptor traffics after it's been internalized. And so although we had expected, and really, we talked about this frequently in the past, we had expected that our AOC is built upon the transferrin receptor would have much broader activity than they did. We were given a gift here, much like the gift that the Galnac conjugates had for the liver where you only address hepatic parenchymal cells with our transparent monoclonal antibody, at least the one we're using. We're seeing activity primarily in striated muscle, and to a lesser extent, smooth, as I said, and very slight activity in a few other tissues, but the distribution of the receptor itself does not necessarily predict the activity in that particular tissue. Ritu also asked another question related to, did we see any effects on the kidney? And the answer is we did not see any effects in the kidney in our tox studies. So again, the data that we have is highly supportive of the fact that we're getting great activity, saturated pharmacologic activity in the absence of adverse effects with using the classical toxicology end points, which have been thoroughly analyzed in that study. The next question comes from Joe Schwartz at Leerink. And Joe is asking, and I'd like to have this one be a tossup for folks that we can go around the table. He was asking about nuclear siRNA. And is there any evidence of nuclear siRNA that siRNA works in the nucleus more effectively in rapidly dividing tissues or in slowly dividing tissues. And to date, I don't know there -- I've seen publicly patients that relate to that specifically. What we do know is that all of the components for siRNA are present in the nucleus. And I think Joe has recently done a review in that area. And I have not seen data that suggests that there are differences between rapidly and slowly dividing cells, but it's certainly an area. I don't know whether Steve or Phil have any ideas on this.

I've not heard that before. I've not read that or seeing that presented at a meeting.

No, I don't think we know the answer to that yet.

Yes. So clearly, the data that we've demonstrated today, and I think that the data that have been demonstrated by labs like David Corey's lab and others have demonstrated that there is nuclear activity of siRNA. And I think some of the data that I showed today demonstrates that we can take advantage of that -- of the nuclear localization of the siRNA machinery to actually knock down nuclear targets. And so that's obviously key to our first program where the toxic messenger RNA is trapped in the nucleus. So I think I'll take this one. And, Steve, you can have a crack at it as well. We have a question from Crédit Suisse -- from Judah from Crédit Suisse, who's asking, can you walk through the process of endosomal escape for the construct. And I'll take a crack at it and I'll let Steve have it. And Steve, of course, has been spending the past 7, 8 -- and I've probably lost track of time, looking at endosomal escape. So what I think is going on, and hopefully, Steve will concur is that there are -- once an oligonucleotide that has been stabilized or modified in order to withstand lysosomal enzymes, once it's in the lysosome, ultimately, the lysosomal membrane is being replaced and turning over, over time, or where there are faults in it, which can be detected using immunohistochemistry. If you look at some of the fluorescent proteins, like if you look at a fluorescent lamp antibody, you can see that the lamp where it will change over time. These are -- these are proteins that are associated with the lysosomal membrane. So we know that the lysosomes was essentially breathing. And it's at least my hypothesis that as the endosome breathes, the oligonucleotide can escape. The antibody has been… [Technical Difficulty]

Art froze, what he was going to say is the antibody has been degraded long prior to this. And it's kind of like going to the moon where you jettison the main rocket once you leave Earth, that's kind of the equivalent of the antibody. So once it's in the lysosome, then because of the chemistry of the siRNA, it's metabolically stable and it's trapped inside this lipid bilayer of the lysosome that is very similar to the lipid bilayer of cell membrane. The answer -- the direct answer to the question is we do not know how you escape from in here to get out here into the cytoplasm. But what we do know is it happens, because we have all these controls and activity, et cetera. As Art was starting to discuss, liposomes are not -- lysosomes are not just this static vesicle type of an endosome. They're constantly fusing with other endosomes with other vesicles as well, too, and they're spinning out MVBs and all these different biology is happening. And every time you fuse or you pinch off a vesicle, there's a breach of the lipid bilayer. And it may very well be that there is a modicum of escape that happens right as those vesicles get pinched off. It could be that there is actually a breach of the lipid bilayer of the lysosome. And then this happens when you look at the clinical trials in liver, it looks like maybe 5 siRNAs escape every hour for up to 6 months. And it may very well be that, plus this combination of the lysosomal vesicles that are fusing and pinching off that would lead to this amount of escape. You only need about 5 or 10 to escape every hour to continue to fill up Argonautes so that you're above this maximal number of siRNAs in the cytoplasm, which is only about 2,000, whereas a small molecule, it's about 100,000 to 500,000 molecules of that small molecule have to be in the cytoplasm in order for it to be active above its threshold concentration. So Art, you got cut off, and I sort of jumped in right in your...

Thank you for picking up the baton. Thank you. We went through 80 testing [ water stocks ] in the whole road show and I've never been cut off before. But I'm joining by my -- tethering my cell phone at the moment. So my apologies for getting cut-off. So I think I'm a lucky guy. I'm glad you are here to pick up at the baton because you might [ fresh ] with it.

So the thing that I would add about the endosome escape is, while we don't know the mechanism, and it may just be an sort of an artifact of evolution where for these really small RNA molecules, siRNAs, there wasn't this protection for having them invaded because prior to RNA interference, they didn't have any genetic information that could alter the nascent cell back in the primordial world. So while we don't understand these mechanisms, we do know that they happen and they happen at very low doses, you're looking at single doses of 3 mg per kg on average that give you a 3-month PD response. And so once we know what these mechanisms are, and academic laboratories like mine and many others around the world, are investigating this, they may present an opportunity for us to design the siRNA or the whole delivery molecule in a way that takes advantage of whatever this mechanism is so that we could further enhance the endosomal escape. We still have this depot effect of 80%, 90% of the molecule in the endosome in the lysosome that could slowly come out over 3 to 6 months, but we can enhance that escape if we understood these mechanisms. It's a new area of research that there was many problems to solve prior to this. This is now the rate-limiting problem is endosomal escape. And there's, as I said, labs around the world at universities and institutions that are investigating this as well as biotech companies. A solution will be identified that will be viable for the clinics at some time in the relatively near future.

Thanks, Steve. It's great to have you, the endosomal escape guy on the panel today, because I think that is a key question. We all know that there's orders of magnitude, more potency that we can get out. The question is whether we can do it safely. We have another question from Josh Schimmer from Evercore. He says great overview, thanks for hosting. More importantly, he's asking, we see a lot of promising preclinical data and do we have thoughts on why there's been a translational gap? Why we've not been able to translate so well from preclinical data to the clinic? And Mike, Phil, I don't know whether you want to take this one?

I'm not sure that's true anymore, right? I mean, I think the most established sRNA platforms can go from target identification to IND in less than 18 months. So you can't achieve that if the majority of your preclinical trials are failing. So I think they're having tremendous success at translating into viable clinical strategies. And thus far, right, there are 3 plus approved sRNA drugs on the market. So I think we're going to see an acceleration of successful clinical programs.

I would just add to that. I think that thinking is sort of in the black and white century, and now we're in the color century. So the molecules today, if they work in nonhuman primate, an NHP, then that's also one-to-one dose carryover and safety profile into humans. And so if you work in a mouse, you would say, wow, okay, maybe it's going to work, maybe it's not going to work. In all likelihood it will. But if it works in an NHP and all the RNA biotechs, including Avidity, I mean NHPs is the go-to model here because it tells us so much information of what the clinical trials will -- the protocol will be set up as what they'll look like. So yes, I think that's kind of a pre-conjugate question, whereas we're in the color world now that's entirely different, much higher odds of success.

And pulling out my toxicology card, since I'm a card-carrying toxicologist. I think many of the drugs that have failed where you didn't get the translation, is you ran into toxicity before you get pharmacologic activity. And with modern oligonucleotide therapeutics and particularly sRNAs and, of course, the relatively nontoxic PMOs, we don't -- we're not running into those problems anymore. So we have the ability to more effectively deliver. We have therapeutic agents which have lower levels of inherent toxicity. So when you combine lower levels of inherent toxicity with lower levels because you're now have targeted delivery, you're going to increase the probability that you're going to achieve pharmacologic action at levels which are therapeutically attractive and which are well within the therapeutic index of a particular compound. So I think -- what is it, Phil?

I'm just going to say, I think that is just a reflection of the fact that sRNAs work catalytically, that very, very small amounts of sRNAs are needed to have a very significant impact on the expression of a target gene. And so the big difference now is we have a platform where the therapeutic index is huge. And you're delivering a very small dose with most of the sRNA in the endosome.

Endosome is acting like a depot for us. So let's move on here a lot for -- we actually have a lot of questions. So we have another question from Chad Messer from Needham, who's looking at the one -- AOC 1001 IND-enabling studies. He's asking whether the differential -- I guess, I'll take this one as well. He's asking whether the differential in potency between skeletal and cardiac muscle is explainable by transferrin receptor biology. And I think the answer to your question, Chad, is that it may be. There are multiple factors that are going on here. I think there may also be greater nonspecific uptake in cardiac muscle so that you may have higher concentrations in cardiac [Technical Difficulty] there's nonspecific uptake of the antibody. But we don't know for sure how that receptor biology might be differing between skeletal muscle and cardiac muscle. But clearly, there are differences in the concentration response curves. On the other hand, clearly, and importantly, for the patients with myotonic dystrophy, we effectively delivered to the heart. And we get effective -- we get effective reductions in RNA, on the toxic RNA expression in cardiac muscle. And so the data suggests that while the potency may not be there, at the doses that we're giving there is -- there are, in fact, effective levels that are being achieved, and we're getting the reductions in the expression of DMPK in both cardiac as well as in skeletal muscle. Mike Flanagan, there is a question that's specifically directed towards you, lucky guy. And that is, should we expect AOC 1044 to be in the clinic before the FSHD AOC?

Yes. I guess, based on the announcement today, I think that's -- you might expect that AOC 1044 would be first, right, to enter in the clinic. But really, as we talked about, FSHD program has accelerated and they're really kind of neck and neck. And I'm not really sure which one is going to enter the clinic. But what I can tell you is that we're looking forward to both programs being in the clinic in 2022. And we'll see how the -- I hate to put it on the teams, but we'll see how neck and neck, we'll see who wins the race. But I think it's a good question on AOC 1044, and we're excited about both programs.

Mike, a question on BD strategy and how we're going to expand the utilities of AOCs and perhaps, Sarah, I can address that one to you.

So thanks, Art. So from a BD perspective, I think it's first important to note that for rare disease, they're the types of programs that we plan to develop and commercialize ourselves. When we look at BD, there's an element around how can we accelerate the technology? And I think 2 good examples of that are our collaborations with Lilly and then with MyoKardia. So the collaboration with Lilly, primarily focused on the immunology space, allowed us to be able to accelerate the technology into a new therapeutic area. It also enables us to work with an expert in that field. So that collaboration is a certain number of targets, 6 targets. So we have the rest of the space to work for our own programs. MyoKardia a similar type of structure, research collaboration single target in this case that allowed us to be able to work with experts in tox in the heart and to learn with them to also then, in turn, be able to develop our own programs. So as you see an approach with regards to expanding the technology, it's very much inclined to very much be a blend of both our own efforts internally as well as also partnering with respective leaders in certain therapeutic areas or certain aspects.

Great. So I have a question from Yanan at Wells, and he's asking in our first-in-human study. So I guess this one is directed to the Avidity team. In our first human study, would it be possible to achieve doses that enable the tissue concentration above the 10th nanomolar concentration that we shared in our EC50 for our nonhuman primate studies. So for example, the high potency of AOC 1001, it would be possible to achieve EC90 in clinical trials. So I guess I will take that one as well. The answer is, of course, we are -- as we negotiate with regulatory authorities for our starting doses and ultimately, the full dose range that we're going to be using in our clinical trials. We would certainly hope to be able to achieve the 10th nanomolar concentrations that were associated with the EC50 in our nonhuman primate studies. And as to whether we could achieve an EC90, I think, certainly, the data suggests that the concentrations that are required there are relatively modest and may be achievable. It really ultimately will depend upon some variables that we can't address today. That is where we start our clinical trials and also how well the data translate from the nonhuman primate to the human, in particular, we will expect that some differences in the disease subjects versus the nonhuman primates that we've been assaying up to this point. However, I think those differences are certainly are addressable with the high potency sRNAs that we're administering as part of our AOCs. There are a couple more questions.

Art, if I could just add one comment to that. So for the audience, when we talk about 3 milligrams per kilograms, because these are much larger molecules than small molecules, so an sRNA is about 25x the size of a small -- an average small molecule that the 3 mg per kg, the number of molecules that the patients being exposed to is 25x less than a small molecule drug exposure. And so the safety profiles are much better. So we're not -- we're talking milligrams. We really should be talking about nanomoles that are administered to the patient. But traditionally, because of small molecules in the pharmaceutical world, we're talking about amounts, milligrams per kilogram instead of nanomoles per kilogram, which would be an apples-to-apples comparison of the actual numbers of molecules. And the number of molecules the patient is exposed to is directly related to safety and toxicity profile.

We have a couple of more questions and then we'll wrap up. There's a question from Joe Schwartz at Leerink. He's asking, if we have positive results in our DM1 study, how much does that read to other diseases? Mike? Sarah?

Well, for me, I think proof of concept. First, proof of concept and just understanding the dose and response in patients is huge, right? You're building on a platform, you have the same transferrin receptor with different sRNAs. So I think that will tremendously help speed and accelerate our internal research to deliver new medicines faster.

Yes. Yes, I think, Mike, to build on your point, the aspects, looking back at our goals when the company was founded around tackling what has been one of the real challenges in the RNA therapeutic space, which is around delivery. So being a -- we're really looking forward to the aspect of starting a program where, being able to deliver RNA therapeutics to muscle. Of course, there's an element of platform in there, as Mike talked about, but also each program in our pipeline of different diseases. And one of the things that we know from rare diseases is that each development program is unique. And part of our strategy also builds very much where we built things like patient efficacy and medical affairs ally from an aspect of really understanding each disease, both from a patient and a physician experience to help us better design our clinical programs. So each clinical program is unique because each disease is unique as well. But of course, there is an element, very much a platform in here as well, which we're really excited about.

I think we've seen this already in the sRNA arena that, of course, the first conjugated sRNA begat the second, begat the third, begat the fourth. And again, you begin to pick up momentum. So I think getting some good momentum going with our DM1 program, where there really is a program where we're talking about a toxic RNA -- knocking down the expression of a toxic RNA really will provide us with a significant amount of momentum moving forward and will allow us to really get to an even faster cadence of drug discovery, getting drugs into the clinic and getting drugs approved for the patients who need them. There's also a question and perhaps Mike and I can address this one. Can you elaborate on the translational value to the nonhuman primate DMPK knockdown, that's the target gene we're talking about, in the healthy nonhuman primates compared to disease state?

Art, do you want to start first?

Sure. Of course. When was I ever shy? So we've obviously thought through that. And with existing data that we and others have generated, we are expecting that there will be a slight reduction in the potency of sRNA in the disease state. I think the data that I showed you, demonstrating that there are differences between nuclear and cytoplasmic knockdown. We saw that there was an 80% reduction in -- 70% -- 80% reduction of cytoplasmic fraction. We had slightly less in the nuclear fraction. We're somewhere around a reduction of 70%. So we know there's going to be a little bit of a difference in the translation there. So in a worst-case scenario, we -- you might think of a fivefold or a tenfold loss of activity. But because the agents that we're using are so potent, I think that any reduction activity we might have related to the disease state should actually end up translating quite well to the -- from the existing nonhuman primate data. So I think the data that we collected to date, the data from previous experience with other oligonucleotide therapeutics, particularly sRNAs, that suggests that the nonhuman primate generally underpredicts for man. Still all bode well for us even if we lose a little bit of potency in the disease state. And certainly, there's no surprise that the disease state, even though we've selected the sRNA, based upon knockdown of DMPK in cells from a human subject with myotonic dystrophy, we selected our sRNA specifically for that, we still know that there are going to be differences in the way that, that messenger RNA conforms in space. It's going to be crowded with muscle [ line ] like protein, which are going to be other proteins that bind to it. So we're expecting that there will be a slight reduction in the potency in the disease state. Certainly, the data -- and in nuclear, often in nuclear RNA -- mRNA. But the data that we've collected to date suggest that, that should be overcome by the sheer potency of the sRNA that we're using in this particular case.

Yes. I mean, when I look at it, the key things are -- as Steve and Phil had indicated, we have nonhuman primate data that translates quite well to humans. Second is that we're using sRNAs that have a broad therapeutic window. So I think given that we see activity in nonhuman primates, we have a broad therapeutic window. I think we can reach those doses that will knock down the mutant DMPK in the clinic. Now it's always a challenge, right? The clinic is always a challenge because patients come in with a variety of different number of repeats, different kind of clinical manifestations of disease, trying to understand how that knockdown of mutant relates to clinical benefit is always a challenge when you have a variety of unique patients coming through for clinical trials and then future treatments. But I'm really -- when I -- honestly, I did diligence before I started, right, on the company because, I mean, it's my career. So I mean I did that diligence and the nonhuman primate data is quite compelling. And for such an early company having 7 different nonhuman primate studies and now GLP, that looks really clean. I mean it's -- I think we have a really good chance.

Great. Thanks. I think that's a really great point to close the discussion and turn it over to Sarah for wrap up remarks. But before that, I got to -- I want to thank Steve and Phil for joining us today and for their expertise. Sarah?

Thanks so much, and thanks also from myself as well as on behalf of the team for Steve and Phil for joining us today. Really good. It's a pleasure to have you on the panel. So in terms of -- firstly, we hope you've really enjoyed the discussion. And thank you very much for also the questions. One of our goals for today was to provide that deep dive into the engineering that has really underpinned the technology as well as that aspect of what we have the potential to be able to do with our technology as well and with our different clinical programs as well as our progress that we've made both with AOC 1001 with regards to entering the clinic in the second half of this year. And then also in terms of advancing AOC 1044 into IND-enabling talks. One of the other aspects as well, very much here for me, I really enjoyed the broader perspective and some of those dreams on the future of the RNA therapeutic space. I very much enjoyed your questions. It's one of the things that we probably enjoy the most is being able to talk about our technology and get into those scientific discussions. So in terms of one of the aspects, we also spoke about a little on the panel is that the aspect of that preclinical proof-of-concept and also looking at additional skeletal muscle and other tissues. So very much AOC 1001 is the beginning with 2 other programs entering into the clinic behind it in 2022. And we hope in terms of much more to come from an aspect of delivering our goal to be able to really impact people's lives and in particular people living with rare diseases, people like Luke, who lives with DM1 today. With that, I'll close out and thanks very much, and enjoy the rest of your day. Take care.