Wave Life Sciences Ltd. (WVE) Earnings Call Transcript & Summary

Good morning, and welcome to the Wave Life Sciences Analyst and Investor Research Webcast. [Operator Instructions] As a reminder, this call is being recorded and webcast. I'll now turn the call over to Kate Rausch, Head of Investor Relations at Wave Life Sciences. Please go ahead.

Thank you, operator. Good morning and welcome to Wave's 2020 Analyst and Investor Research Webcast. The slide presentation that accompanies this webcast is available in the Investors section of our website at www.wavelifesciences.com. Before we begin, I would like to remind you that management may be making forward-looking statements during today's presentation. These statements are subject to a number of risks and uncertainties that could cause our actual results to differ materially from those described in these forward-looking statements. The factors that could cause actual results to differ are discussed in our SEC filings, including our annual report on Form 10-K for the year ended December 31, 2019, and our quarterly report on Form 10-Q for the quarter ended June 30, 2020. We undertake no obligation to update or revise any forward-looking statement for any reason. I would now like to introduce today's speakers. On the call with me today are Dr. Paul Bolno, President and CEO of Wave Life Sciences, who'll begin the presentation this morning with Wave's vision and strategy for becoming a fully integrated genetic sciences company. We also have Wave's Chief Technology Officer, Dr. Chandra Vargeese, who will present an update on our PRISM platform; and Dr. Kenneth Rhodes, Wave's Senior Vice President, Therapeutics Discovery, who will discuss our neurology pipeline and C9orf72 program. Following the presentations, we will open up the call for Q&A. I'd now like to turn the call over to Paul Bolno. Paul?

Thanks, Kate. Good morning, and thank you for joining us today for our 2020 analyst and investor research webcast. I'm truly excited about the updates we have to share with you today as they reflect years of learnings from an evolution of our platform as well as the hard work and innovation of everyone at Wave and our research collaborators. Throughout this dynamic period, our vision has remained clear, constant and compelling. And today, I'm proud to say we have taken significant steps forward towards the ability to develop effective treatments for patients diagnosed with genetically defined diseases. At Wave Life Sciences, we're building a fully integrated genetic medicines company to address the enormous unmet medical need and burden caused by mutations in the genome. Today, there are more than 6,000 genetically defined diseases, and the global prevalence of all monogenic disorders at birth is approximately 1 in 100. Across the globe, we see dramatic increases in genetic testing and a growing understanding and definition of diseases at the molecular level. We've built Wave to leverage these trends and alter the course of diseases that have proven to be intractable and beyond the reach of existing medicines. As a patient-focused, research-driven company, our sustained investment in our platform allows us to advance and deliver on our mission, and we have made great progress in the evolution of our unique RNA-focused platform. Our ability to control stereochemistry of oligonucleotides and rationally designed single drugs serves as a unique foundation to derive insights from chemistry and apply them to biology, resulting in the exciting platform and program data we will share today. The large body of data we have generated over the last 8 years across sequences, chemistries, modalities, tissues and cells has allowed us to leverage machine learning to further refine and accelerate our ability to rationally design potential medicines. We have remained focused on intervening at the RNA level where we have the potential to address diseases that are difficult to treat with small molecules or biologics, where we retain the ability to titrate dose and where we avoid permanent off-target genetic changes and other challenges associated with DNA editing or gene therapy approaches. To accomplish such an important mission, there are 4 key goals we set out to achieve as we built and evolved PRISM, our proprietary discovery and drug development platform. We needed the ability to address different types of targets and not be limited to a single modality. A significant advantage of our platform is that we can target RNA through several mechanisms, including silencing, such as RNase H-mediated degradation or Ago2-mediated RNAI; splicing; and ADAR editing. And it is because of our focus and continuous investment in understanding PRISM that we are able to reveal and unlock the ADAR editing modality, which has the potential for wide-ranging applications and is applicable across nearly all tissue types. Having the ability to edit RNA significantly expands our target universe, and we have been motivated by the enthusiasm of our ADAR editing capability from a diverse breadth of stakeholders. Next, we needed the ability to optimize the pharmacologic profile of therapeutic oligonucleotides. This morning, Chandra will focus on our ability to optimize potency, exposure and durability and will walk you through a set of preclinical data that demonstrates the evolution of our chemistry engine. Following that, Ken will provide deeper insights as to how we are employing these new chemistries and modalities to build a transformative neurology franchise as well as the latest data from our promising C9orf72 clinical candidate for the treatment of amyotrophic lateral sclerosis and frontotemporal dementia. Thirdly, the advances we have made to our platform enabled successful target engagement across different tissues. Within neurology specifically, we have demonstrated broad distribution to and target engagement in key cell types within the central nervous system. Our PRISM-derived compounds can access RNA in both the nucleus and cytoplasm without the need for a delivery vehicle. Lastly, we believe scalable and cost-effective manufacturing of nucleic acid technologies is critical. Unlike other technologies, oligonucleotides have the advantage of well-established manufacturing processes and validated test methods based on decades of improvements. We continue to invest in process development enhancements and have established a GMP manufacturing capacity that is scalable and ensures we have sufficient supply to advance our platform and all of our programs. We have invested significant capital in developing our platform over the past 8 years to address all of these goals. Now more than ever, I believe, we are in an exciting position with our pipeline, our technology and our team to deliver transformative results. So how do we put Wave's platform in the context of others? Oligonucleotides have a long history with the original PS chemistry modifications used to stabilize the backbone dating back to the 1970s, and there have been more than 30 years of innovations and learning since the traditional [ gapmer ] chemistry was introduced. While other backbone modifications have been developed along the way, their utility has been limited. With PRISM, we have leveraged those learnings while simultaneously charting new territory with our unique platform innovations. Core to the value of our platform is our ability to design and develop stereopure oligonucleotides as compared to stereorandom mixture-based ones being advanced by others. We have previously discussed, shared and published the preclinical work in support of our stereopure approach, including at our October 2019 Research Day. With this focus on stereochemical control, we intend to be the first to fully characterize and investigate the structure-activity relationship of all RNA therapeutics in our pipeline, as has become standard with small molecule and antibody development. We have recently seen others follow suit in this approach. Based on the exciting data we will share today, we remain committed to using stereochemistry as a foundation to elucidate structure-activity relationships and develop precise and rationally designed medicines that leverage the full potential of RNA therapeutics. We continue to push the boundaries of nucleic acid chemistry, including the use of a new backbone chemical modification in our oligonucleotide design. Controlling stereochemistry allows us to better understand structure-activity relationships relevant to chemistry and different sequences, and I'm excited to have Chandra share data on the benefits of our novel backbone chemistry shortly. In summary, our platform is more than just stereochemistry or 1 single chemical modification on its own. Through PRISM, we identify, aggregate, leverage and deploy pharmacological insights with a deep understanding of the interplay among sequence, chemistry and stereochemistry. Importantly, we have a strong and extensive intellectual property position relating to stereopure oligonucleotides and our novel backbone chemistry modifications. With each new target, we learn. These learnings feed into PRISM and are implemented into new programs. This is a continuous cycle that provides insight into the relationship between sequence, chemistry and stereochemistry and how to optimize compounds accordingly. As we showed last year, this has significantly improved the hit rates from our screens, starting with 10% to 15% hit rates with our stereorandom screens. Today, we are reaching hit rates of up to 80%, far exceeding industry standards. Additionally, we've been able to open up new sequence space that has been ignored or overlooked, allowing Wave to pursue new potential target sites and accelerate our discovery pipeline. While the opportunities for our technology are vast, we are focused on neurology where there is a very large and growing number of neurodegenerative and neurodevelopmental diseases with high unmet need. As others have just recently begun to recognize the opportunity in this space, our years of investment have positioned us well to succeed in this area. We have been able to achieve broad anatomical distribution with our PRISM design compounds in the CNS and demonstrated productive target engagement across multiple CNS cell types with multiple modalities. We have also built deep in-house neurology expertise across all functional areas. In CNS, our partner, Takeda, has an option to opt-in to any of our Category 1 Programs, which include our allele-selective HD programs, our C9 program and our SCA3 program. For the HD programs, this allows Takeda to review proof-of-mechanism clinical data from our promising SNP3 program in addition to the results from the ongoing PRECISION-HD clinical trials. Within the Category 1 Programs, there are potential milestones that would offset our development expenses. We are halfway through our 4-year exclusivity period with Takeda on our Category 2 CNS programs. We are collaborating with Takeda on up to 6 preclinical targets. We received annual committed research support payments for at least 4 years, with additional funding for ongoing programs committed for a period thereafter. And we are eligible to receive more than $1 billion in precommercial milestones and royalties for these programs. Beyond our collaboration with Takeda, we have significant growth opportunities using our prism toolkit to discover new targets and expand our wholly owned neurology pipeline. Most recently, we are particularly excited about targets that can be unlocked with our ADAR editing modality. Strategically, we believe that our focus on and capabilities in neurology will enable us to fulfill our vision and achieve the goal of building a fully integrated genetic medicines company. Ken will share more later as to how we are employing new chemistries and modalities to build a transformative neurology franchise later in the presentation. In developing our platform, we have and will continue to identify opportunities outside of neurology. As such, we are exploring several ways to leverage our platform discovery research and build out areas of potential new biology through collaborations, partnership and licensing agreements. We will remain disciplined. And while our focus is neurology, we have made strategic decisions to ensure that our innovative chemistry capability is available to external academic, advocacy and industry partners. The potential of PRISM is vast and the unmet medical need is enormous, and our ultimate goal is to ensure that we maximize the value of PRISM for our shareholders as well as patients and the advancement of science. As a prime example, we expect to announce our first ADAR editing program in a hepatic indication later this year, pushing the boundaries of what currently is believed to be possible, and we know this technology could be applicable to other therapeutic areas as well. Turning to our current pipeline. As I've just touched on, our pipeline is focused on neurology and is led by our first-in-class, allele-selective Huntington's disease, or HD, programs, including our SNP1 and SNP2 programs, which are currently in Phase IB/IIA clinical development. While our clinical studies will not be part of today's discussion, as we reported during our Q2 earnings call on August 10, we expect to report data from both the PRECISION-HD1 and PRECISION-HD2 studies as well as data from both open-label extension studies in the first quarter of 2021. Importantly, we take the learnings from 1 program and apply them to the next. A key example of this is our third allele-selective candidate for HD, SNP3, which we are introducing today at WVE-003. WVE-003 incorporates our new backbone chemistry in the candidate design as well as learnings from in vivo target engagement studies and were not possible with our SNP1 and SNP2 programs. There have also been clinical learnings from our PRECISION-HD1 and 2 studies incorporated into our SNP3 program, including methods for patient identification. We expect to submit a CTA for WVE-003 in the fourth quarter of this year. Our pipeline also includes our C9orf72 program for amyotrophic lateral sclerosis and frontotemporal dementia. And I am pleased to introduce our C9 candidate as WVE-004. We expect to submit a clinical trial application for WVE-004 in the fourth quarter, expanding our clinical neurology portfolio beyond Huntington's disease. All of us at Wave are excited to bring this candidate forward to address these 2 devastating neurologic disorders. Ken will be discussing more about the WVE-004 today and sharing new preclinical data. On Slide 13, you will notice that our preclinical and discovery programs are all stereopure, and our novel backbone chemistry, or PN, is incorporated or being explored in these programs. Chandra will describe PN chemistry in a few moments. Looking to the future, we are driven and motivated by the opportunity to realize the value of our clinical and preclinical programs as well as the innovations coming off our PRISM platform. We expect to have 4 global clinical neurology programs next year with multiple data readouts by 2022, and we are well positioned to deliver multiple clinical trial applications over the next 3 years. We are leveraging our platform to bring new neurology targets, including editing targets to the clinic, and we have the potential to realize further value through new collaborations. All of these exciting programs and assets have been derived from continuous learnings from our PRISM platform and our ability to isolate single isomers for rational drug design. Of course, behind these programs and innovations is an extremely talented and dedicated team at Wave. With that, I'd like to turn the call over to Chandra Vargeese, chief Technology Officer, to shed more light on our recent platform evolution and new chemistry advancements. Chandra?

Thanks, Paul. Good morning to everyone on the webcast, and thank you for joining. As someone who has been working in the oligonucleotide field for more than 30 years, I'm proud and excited by the data that we will share this morning. As many of you know, naturally occurring nucleic acid, both RNA and DNA, are not suitable for use as therapeutics. However, multiple features of the nucleic acids are amenable to chemical modifications. These features, sequence, chemistry of the sugar and backbone and stereochemistry of the backbone from the foundation of PRISM, our discovery and development platform. On PRISM, we have got an opportunity to investigate the relationship among these features with a depth that has not been possible with any other platform. We are uniquely poised to unlock the value of backbone stereochemistry and to understand its interaction with other features of the molecule, including sequence changes and chemical modifications. We talked with you before about how our chemistry advances allow us to control the stereochemistry of chiral backbone modifications, exemplified by phosphorothioate, our PS modifications. At Wave, our initial investigations into the impact of backbone chemistry and stereochemistry of the oligo pharmacology, focused on widely used PS and PS/PO backbone chemistry. Today, we are excited to share the expansion of our repertoire of backbone chemistries and modifications and their impact on oligonucleotide pharmacology within the introduction of -- with the introduction of PN backbone chemistry. With PN modifications, a nitrogen atom replaces a nonbridging oxygen atom. We'll focus on one of these new PN modifications, one containing phosphoryl guanidine, and show how judicious use of this backbone chemistry can profoundly impact the properties of our stereopure oligos. Like the PS modification, PN modifications are chiral. We have developed the building blocks and synthetic capabilities to control the chirality of this backbone linkage. As you can see in the center of the slide, Sp and Rp stereoisomers are PS modifications, which equate to the right-hand and the left-hand positions and are indicated by blue and red carrots. Likewise, you can see on the bottom right of the slide, we represent Sp and Rp chiral linkages of PN modifications with the blue and red brackets. So they are very distinguished from our stereo PO/PS modifications as well as PO modifications that may be included on the mixed backbone. Unlike PS modification, PN modifications are neutral, meaning that the negative charge in oligonucleotide is reduced with every PN modification added to the backbone. Essentially, PN modifications break up the charge of the backbone. The introduction of PN modifications under the oligo backbone retains complementary base pairing and specificity. So today, we'll demonstrate that rational application of PN modification affects oligonucleotide activity across modalities, including silencing, splicing and editing. With each modality, we will show you that incorporation of PN backbone chemistry modifications into PRISM is generally improving the pharmacological properties of our oligos by highlighting examples where it improves the potency, tissue exposure and durability of stereopure oligos. This is the framework I'll walk through on the upcoming slides. As we touch on each data set, I'll refer the mixed backbones of oligonucleotides that contain PN modifications as PN chemistry. To illustrate the impact of PN on potency of a silencing modality, I'll walk you through a data set from our screens for identifying RNase H-targeting sequences in iCell neurons in vitro using free uptake conditions. This screen was initially performed with stereopure molecules with PS/PO backbone modifications, and the potency of the oligos are rank ordered from left to right. Now I'm going to show you what this head-to-head comparison looks like with the same molecule, same sequence and same 2' chemistry but with the addition of PN chemistry at various backbone lengths. We repeated this screen with the safe molecule where we introduced just a few selectively placed PN linkages, as you can see in navy. The sequences and other chemical modifications on these molecules are unchanged from the molecules with PS/PO modification as shown teal. The introduction of few PN linkages significantly increases the potency of vast majority of stereopure PS/PO molecules, with approximately 80% of them yielding at least 75% knockdown. We are very excited by results such as these, which enable us to target sequence space which would otherwise be inaccessible and ensure that we are not restricted by regions in the target transcript. Now we need to -- so now we are moving to in vivo incorporation of PN chemistry. In vivo incorporation of PN chemistry is having a more significant impact on our RNase H molecule. We are looking at data from my evaluated 10 weeks after a single dose. By incorporating just a few linkages, we see persistent transfer knockdown by 80% to 90% throughout the central nervous system, including spinal cord, superficial brain regions, as the cortex, and deep brain regions, as the striatum. If you compare the persistence of knockdown and relative activities across tissues of CNS, this data illustrates the profound impact that PN chemistry can have on durability and tissue exposure. Again, we have observed similarly profound durability benefits in a second experiment, which uses the exact same 2 molecules in a different tissue type. In this experiment, we evaluated 9 months after single intravitreal dosing in the eye, and knockdown at the 50% threshold still persists. We expect the durability and tissue exposure benefit from PN chemistry illustrated on these 2 slides to open up new indications and target space for neurology pipeline. Turning to a second modality, slicing. Some of our initial work with the PN modification has been explored with exon skipping as a part of our earlier work in muscle. In fact, the Exon 53 program we had been advancing last year is the first real program to introduce PN modification. Today, I'll share several new data sets comparing the impact of few stereopure PN modification on the backbone of the compounds with identical sequences and 2' chemistry modification, as shown by the 2 structures on the right-hand side of the slide. These are both new compounds that we have never shared before, and this is the first time we are sharing data using a stereopure modification on an Exon 23 compound. Similar to the plot I showed previously for RNase H modalities, this plot shows PS/PO molecules depicted by teal dots rank ordered from left to right based on their potency in exon skipping assays in myoblast. Keep in mind that with exon skipping, we are restoring expression, so more potent molecule in this graph are shifted upwards. As you can see by the navy dots, judicious and rational applications of PN chemistry to otherwise identical molecules causes an overall upward shift in activity, representing a substantial potency gain for the most part. To highlight the impact of PN chemistry on exon skipping, we turned to DMD Exon 23 as an example. The graph on the left shows exon skipping data for compounds that differ only by the inclusion of a few PN linkages. At no concentration, the PN-containing oligos are about tenfold more potent than our stereopure competitor. On the right, we have evaluated the relative uptake of these molecules in cultured myoblast. We detect 2 to 3 fold more PN-containing molecules in both cytoplasm and in the nucleus compared to the PS/PO compounds, and this is statistically significant. So now turning to the -- turning to exon skipping. On the Exon 23 molecules, I highlight the impact of stereochemistry. We turn into DMD Exon 23 as an example. The graph on the left shows exon skipping data for compounds that differ only by the inclusion of few PN linkages. So now the improved nuclear uptake will be driving part of the potency benefits observed with PN chemistry as exon skipping oligos act on pre-mRNA in the nucleus. Now to determine whether exon skipping improvement due to PN modifications observed in vitro translate in vivo, we turn into mouse model for DMD with a devastating phenotype called the double knockout mice, or DKO mice. Unlike the MDX model, we only -- which only has a mutation that eliminates dystrophin expression, the DKO model has a utrophin dilution, which eliminates the compensatory activity of utrophin in mice. Because of the extreme phenotype, DKO mice had a very high bar for evaluating activity in preclinical models, and thus, they're challenging to work with. This work was performed in collaboration with Professor Matthew Wood at University of Oxford. In this slide, we show a survival curve that illustrates the natural lifespan for these mice in orange, with median lifespan of approximately 7 weeks. For context, MDX untreated control mice live a normal life span. Treatment with stereopure molecules with PS/PO backbone modification extends the median survival of this mice to approximately 12 weeks, as shown by the light blue curve. Treatment with the PN-containing molecule provided a profound survival benefit to these animals, extending median lifespan to at least 37 weeks, as shown by the navy line, when the experiment reached completion and was terminated to further evaluate tissues from these animals. And now repeating these experiments with PN-containing molecules is a biweekly 75 mg per kg dosing regimen, which is a 75% decrease in total dose compared to the initial study. Although this experiment is still ongoing, these mice are now more than 29 weeks old, and they still appear very healthy. We were surprised and excited by the survival results we just showed and, thus, elected to do more testing in these animals treated with PN chemistry-containing compounds. As shown by the PBS control group on this slide, DKO mice have a devastating penetrate and typically do not survive on. We evaluated rescue of other phenotypes associated with muscular dystrophy in these animals. Specific force normalizes maximum force produced by the muscles to its cross-sectional area. Specific force in DKO mice, as shown in orange on the left, is significantly reduced compared with wild-type controls, as shown in black. Mice treated with PN-containing molecules perform like wild-type mice in this analysis, shown by the navy line. Moving to the chart on the right. Eccentric contraction force measures force over sequential contraction as contractions-induced injury in dystrophic muscles can decrease muscle force over time. Once again, mice treated with PN containing molecules performed like wild-type mice in this analysis. One last example on exon skipping. We conducted a separate 6-week study designed to assess the PK/PD relationship for PN chemistry as compared to those with PS/PO modifications. We found that the PN-containing compound accumulated to higher levels in all muscle types compared to the PS/PO compound. The PN chemistry also led to more exon skipping and more dystrophin restoration in all muscles, but especially in the heart and diaphragm. But in another example, the introduction of just a few PN linkages with no delivery vehicle and no candidate significantly improves the PK/PD profile for stereopure compounds. The significant differences we see in difficult-to-reach muscles, like the heart and diaphragm, likely explains the profound survival benefit observed in these DKO mice. In summary, these data are very exciting and important to understanding the benefits of PN chemistry in the context of splicing. Now our third and newest modality, ADAR editing. It's one that I'm particularly excited to discuss with you today. We have only recently opened this modality as a direct result of the advances we have made with the PRISM platform over the past 8 years, including chiral control and PN chemistry modifications. In our ADAR editing approach to RNA editing, we employ sharp chemically modified oligonucleotides to recruit endogenous RNA editing advents called ADAR to change a specific adenosine to inosine in the target transfer, which the cells read as guanosine. The result is effectively a change of an A to G in RNA. A-to-I editing is a common post transcriptional RNA modification that generates transcriptomic diversity as ADAR enhance is ubiquitously expressed across tissues. Beyond offering advantages over gene editing. This technology is unique, within RNA editing. We are at the forefront of developing this capability by leveraging endogenous ADAR proteins, which avoids the risk of immunogenicity from exogenous proteins and the potential related off-target effects. Our technology does not require a delivery vehicle, such as AAV, and all of the nucleotides typically have 30 basis or fewer. Importantly, our ability to control the chirality of the backbone enables us to maximize the endogenous ADAR activity. In our initial therapeutic investigations, we are using GalNAc conjugated oligonucleotide for hepatic targets. And as we continue to build our RNA editing capabilities, we expect this technology could be used across various therapeutic indications. Nearly half of the human pathogenic SNPs are GTA mutations. The unique capability of ADAR to correct these mutations creates significant opportunities for us to potentially treat a broad spectrum of human diseases, including diseases that currently have no treatments or only suboptimal treatments. The application of PRISM to RNA editing opens the door to a whole range of therapeutic applications. ADAR can be used in multiple ways to restore protein function, to modify protein functions and to increase protein expressions. Over the past 8 years, we have made significant investments in our PRISM platform and have evaluated more than 1,000 ADAR editing oligonucleotide to produce insights into the relationship between an oligonucleotide structure and its ability to elicit ADAR editing activity. We have leveraged these learnings to accelerate movement into new modalities. Here, we show the activity of beta-actin editing stereopure oligonucleotides with and without PN linkages and compared to matched stereorandom controlled oligonucleotide, shown in black, in primary human hepatocytes. These oligonucleotides are GalNAc-conjugated to increase the uptake in hepatocytes. As you can see here, the additional PN chemistry to the backbone substantially improves both potency and editing efficiency. As we have previously described, we have achieved efficient RNA editing in vitro with our oligonucleotides across a wide variety of cell lines, including nonhuman primate and human primary hepatocytes. As shown here, we have observed potent, dose-dependent RNA editing with 3 chemically distinct stereopure oligonucleotides via GalNAc-mediated uptake. Our next task was to determine whether these results translated to an in vivo system, which they did. For this study, we dosed nonhuman primates subcutaneously once a day for 5 days with the same 3 chemically distinct RNA editing molecules. We took liver biopsy samples at baseline and 2 days after the last dose and evaluated editing of the transcript. As previously shown, we detected up to 50% editing as compared to baseline of 0, 2 days after the last dose. Remarkably, this effect is durable. We continue to see significant editing 45 days after the last dose, as shown in the chart on the left. Peak height area on the right confirms that a significant amount of oligonucleotide is still detectable in the liver at that time. Sanger sequencing allows ADAR to be quantified from peak heights of sequence traces. As you can see on the slide, these plots show 0 editing at baseline and durable editing at the target site 45 days after the last dose. Next, to evaluate specificity of ADAR editing oligonucleotides, we performed RNA, seeking primary human hepatocytes. On the left, you can see total sequence coverage across the Mpl beta acting transcript from the mock-treated group shown on the top and the oligo-treated samples shown on the bottom. The percentage of unedited T and edited C leagues are indicated for each group. As you can see, the editing is only detected at the targeted sequence in the acting transcript. To assess off-target for the whole transcriptome, we applied a mutation-calling software to call edit sites. From this analysis, we observed nominal off-target editing across the transcriptome. Sites where potential off-targeted editing occurred mapped predominantly to noncoding regions of the transcriptome and had either low rate coverage in analysis or occurred at low percentages of less than 10%, indicating that these are relatively rare events. In both analysis shown on the left and right, we find a high percentage of editing that is specific for the target site in the acting transcript. We have also performed off-target analysis in our nonhuman primate experiments and observed no overlap in vivo of the low confidence off-target seen in our in vitro sample, which further supports the specificity of ADAR editing. The next question we started to ask -- answer was if we could achieve ADAR editing without GalNAc conjugation. As the steps towards expansion -- expanding application of our RNA editing modality to the central nervous system, we have assessed editing in vitro in both neurons and astrocytes. Our PN-containing stereopure molecules elicit efficient editing in both iCell neurons and iCell astrocytes, with EC50 for astrocytes reaching the 200 nanomolar range in vitro. Keep in mind, these potencies are obtained with chemical modifications to the oligonucleotides alone under free uptake conditions. There is no delivery vector and no conjugate used in these experiments. I'm excited to share with you preliminary data from ongoing experiments investigating the suitability of RNA editing modality for CNS indications. We have now evaluated editing activities with PN-containing stereopure oligos after a single injection into the CNS of our proprietary humanized mouse model. We see approximately 20% editing activity across CNS tissue, with 50% or more editing activity in several of them. We're very excited about these results, as they are preliminary findings with editing compounds that targeted transcripts that is challenging to edit efficiently, and we are still detecting good editing efficiency throughout the CNS. Further optimization work of our stereo editing compounds is underway, and we look forward to sharing additional in vivo results in CNS very soon. Today, we have shown you that the judicious and rational use of PN modification leads to significant changes in the pharmacology of oligos across modalities. While PN chemistry is important and exciting, it's a proven platform that has allowed us to unlock the value of this novel modification. When we created PRISM, we began with a bold idea that backbone chemistry and stereochemistry matter. It's only because we looked beyond the 2' position of rivals and considered the entirety of chemical modification available to us that we have recognized the value of PN chemistry. With PN chemistry and other PRISM innovation, we have gone beyond silencing and slicing and unlocked ADAR editing with endogenous ADAR enzymes. We have been able to move swiftly with our discovery work, and we continue to expand -- continue to expect to announce our first ADAR editing program in a hepatic indication later in this year. We are working to quickly expand the repertoire of tissues where we can apply ADAR editing, including our focus in neurology. With that, I'll turn the call over to Ken Rhodes to discuss our growth opportunities in neurology specifically. Ken?

Thanks, Chandra, and good morning, everyone. The data that you have just seen underscore the many reasons why I'm excited to have joined the Wave team and have the opportunity to put this elegant and expanding platform to work in developing new therapeutics to address neurologic diseases. We're in an incredible period in neurology drug discovery. Key genetic drivers and risk factors for many neurologic diseases have been identified, enabling to leverage our PRISM platform to deliver medicines that directly target underlying disease mechanisms. With ADAR editing, we have a powerful new modality that can be used to advance novel therapies, and we expect ADAR to become an important component of our neurology strategy moving forward. Our growing neurology pipeline shapes up as follows: as Paul described, in the clinic, we have our allele-selective SNP1 and SNP2 programs for Huntington's disease with data from both ongoing trials as well as our open-label extension studies expected in the first quarter of 2021. Next, our allele-selective SNP3 program, also targeting Huntington's disease, is expected to begin clinical development with a CTA submission in the fourth quarter of this year. And our variant-selective C9orf72 program is also expected to begin clinical development with a CTA submission in the fourth quarter of this year. As Paul shared at the outset of this call, our SNP3 and C9orf72 programs incorporate our novel PN chemistry backbone modification designed to offer increased potency and duration of action. Behind those programs, our discovery in preclinical pipeline includes multiple programs, partnered with Takeda, targeting diseases of the central nervous system. Among these programs, we have incorporated or are exploring the incorporation of PN backbone chemistry modifications to our lead molecules. For the next portion of this presentation, I'll be speaking about our C9orf72, or C9, program and WVE-004, our C9 candidate. First, a bit of background on C9. C9orf72 hexanucleotide repeat expansions are the strongest known genetic driver for the more common, noninherited or sporadic and less common inherited forms of ALS and FTD. ALS is a fatal neuromuscular disease resulting from the degeneration of motor neurons in the brain and spinal cord. FTD is the second most common form of dementia after Alzheimer's disease and results from neurodegeneration in the frontal and anterior temporal lobes of the brain. Both diseases represent areas of high unmet need despite there being 2 approved therapies for ALS. There are no approved therapies or disease-modifying therapies for FTD. There are approximately 2,000 patients living in the U.S. with ALS that carry a C9 repeat expansion, and approximately 10,000 patients living in the U.S. with FTD that carry a C9 repeat expansion. The C9 gene provides instructions for making C9 protein, which appears to play a key role in neurons and immune cells where it functions in biological processes related to endosome trafficking, protein homeostasis and immune cell activation. Hexanucleotide repeat expansions in the C9 gene lead to reduced expression of C9 protein, accumulation of repeat transcripts and RNA-binding proteins in the form of nuclear RNA foci, an aberrant expression of neurotoxic dipeptide repeat proteins, or DPRs. The importance of wild-type C9 protein has been highlighted with the creation of mouse models that lack the mouse ortholog of C9orf72. These mice demonstrate an enhanced immune response and an enlarged spleen, indicating that the C9 protein plays a role in immune cell activation. Moreover, see when expression of C9 protein is reduced, neurons become more susceptible to toxicity caused by the dipeptide repeat proteins produced from the repeat containing C9 transcripts. The hexanucleotide repeats in C9orf72 likely contribute to ALS and FTD through multiple mechanisms that individually or collectively contribute to disease. First is the reduced levels of C9 protein caused by affluent efficiency of the repeat containing C9 allele. As mentioned previously, in preclinical models, loss of the normal C9 protein renders neurons more susceptible to DPR toxicity, making it imperative that any potential therapy preserve C9 protein. Second is the accumulation of RNA transcripts containing the hexanucleotide repeats. These repeat containing transcripts accumulate in cell nuclei, leading to an accumulation of RNA binding proteins forming large abnormal RNA foci, which can disrupt expression and processing of other genes. Last, the repeat containing mRNA transcripts can be translated through an atypical mechanism called RAM translation into aggregation prone polypeptides containing long dipeptide repeats, the DPR proteins. The DPRs can trigger cellular toxicity through a variety of downstream mechanisms. The goal of our C9 program is to reduce the accumulation of repeat containing transcripts, thereby reducing RNA foci and production of DPRs, while preserving expression of the normal C9orf72 protein. Our clinical candidate is designed to selectively silence the pre-mRNA repeat containing variance that ultimately lead to DPRs and RNA foci. These variants are commonly referred to as V1 and V3. Importantly, our candidate does not target the V2 transcript, which is the main contributors to C9 protein expression. The selectivity is achieved through a targeting strategy that directs our therapeutic candidate to a sequence that is only accessible in V1 and V3 transcripts. As you will see in the upcoming slides, our candidate provides potent, selective and durable knockdown of repeat containing C9 transcripts and the DPRs in preclinical model systems while preserving expression of the normal C9orf72 protein. WVE-004 is designed with our PN chemistry backbone modification and was optimized for potency and preferential activity against repeat containing V1 and V3 transcripts. In this experiment, we showed that our candidate potently and selectively reduce V3 transcripts in induced pluripotent stem cell-derived motor neurons made from a patient carrying C9orf72 repeat expansion. As shown in the figure on the left side of the slide, the IC50 of our candidate under free uptake conditions is approximately 200 nanomolar. On the right side of this slide, our data comparing our candidate with a non-targeting control ASO, showing the selectivity of our candidate for the repeat containing V3 transcripts. Building upon the potency observed in vitro, we next explore dose response relationships for WVE-004 in vivo using a mouse back transgenic model engineered to over-express the human C9orf72 repeat containing sequence. In this study, we gave ICD doses of our therapeutic candidate at increasing dose levels to the mouse. One dose was given on day 0, and the second dose was given on day 7. 6 weeks after dosing, we assessed the levels of V3 mRNA and the Poly(GP) DPR polypeptide. We also assessed tissue concentrations of our candidate. As you can see, administration of WVE-004 produced a dose and concentration dependent decrease in V3 transcripts and the Poly(GP) DPR in spinal cord tissue. In this same study, qualitatively similar dose-dependent knockdown of V3 transcripts and the Poly(GP) DPR protein were observed in mouse cortex. One of the important features of our PN containing molecules is they show potent knockdown of target sequences and a long duration of action in vivo. This slide shows the results of an in-vivo study in the back transgenic model where we gave a single ICV dose of our therapeutic candidate on day 0 and a second dose on day 7. 8 weeks later, we assessed levels of D3 transcripts Poly(GP) DPR protein and levels of C9 protein as a marker for the specificity of our targeting strategy. In spinal cord, we saw potent knockdown of V3 transcripts, reducing them by approximately 80% and also a dramatic reduction of a Poly(GP) DPR by over 90%. We also observed complete preservation of C9orf72 protein expression. These effects were sustained out to 8 weeks, the last time point of the study. As we've previously presented in this study, we also saw a potent and durable knockdown of V3 transcripts and Poly(GP) as well as preservation of C9 protein expression in the cervical cortex. Overall, this pattern of activity confirmed our variant selective targeting strategy and clearly demonstrated that our candidate has potent and sustained activity in brain regions associated with ALS and FTD. At the conclusion of this 8 week study, we used an In Situ Hybridization histochemistry method called ViewRNA to image the cellular and subcellular distribution of our therapeutic candidate in the CNS. To remind you of the experiment back transgenic mice received an ICV injection of WVE-004 or PBS on day 0 and day 7. 8 weeks later, brains were removed and sectioned and processed to visualize the distribution of WVE-004. The presence of our candidate is revealed as red punctate staining in the cytoplasm and nucleus of animals treated with a clinical candidate, but not in animals treated with PBS. As shown here, WVE-004 penetrates into motor neurons in the anterior horn of the spinal cord and neurons in the deep layers of neocortex. The clear signal for oligonucleotide in nucleus of label cells as marked by the Blue Arrow heads, indicates that the molecule has access to the cellular compartment or C9orf72 repeat containing pre mRNA transcripts are located. Together with the knockdown of V3 transcripts and DPRs, the ViewmRNA data, are very encouraging as they clearly demonstrate our clinical candidate reaches therapeutically relevant target neurons in spinal cord and cortex. WVE-004 also clearly evokes potent and durable pharmacodynamic responses in these regions. As in the examples that Chandra shared during her presentation, adding PN chemistry to the oligonucleotide backbones and our C9 program, improved potency in reducing repeat containing transcripts in vitro, PN chemistry also improved potency in vivo. When compared to an identical sequence without PN chemistry shown here in the light blue circles, the addition of the PN modification represented by the dark blue circles resulted in greater knockdown of C9 repeat containing transcripts at all oligonucleotide tissue concentration. Encouraged by these exciting in vivo results, we initiated a follow-on study designed to further explore the duration of action of our C9 candidate in transgenic mice. In this study, we examined the effects of single ICV doses of our candidate given on day 0 and day 7 on V3 transcripts and Poly(GP) out to 24 weeks or roughly 6 months following the initial doses. As shown here, we observed a remarkable 60% to 80% knockdown of V3 transcripts and spinal cord and 40% to 50% knockdown on repeat containing transcripts in cortex, 6 months after dosing. Moreover, 2 doses of WVE-004 on day 0 and day 7 of the study reproduced a greater than 90% knockdown of the Poly(GP) DPR protein in spinal cord and an 80% or greater knockdown of the Poly(GP) DPR in Cortex. As marked by the orange boxes, these dramatic effects persisted for at least 6 months following the initial dose. These impressive results are particularly exciting as we consider dosing at intervals in the clinic. I'll now provide a brief update on our clinical development plans for WVE-004. In our proof-of-concept clinical study, we plan to include both ALS and FTD patients with the intention to advance development in both indications. Specifically, we expect to enroll patients with confirmed diagnosis of ALS or FTD, and consistent with our precision medicine approach, a documented hexanucleotide expansion of the C9orf72 gene. Single and multiple ascending doses will be explored along with safety and tolerability. As in our preclinical in vivo studies, we have the ability to sensitively measure the Poly(GP) biomarker in human CSF which will afford us the opportunity to assess signals of target engagement in the clinic. We also intend to look at neurofilament light chain as well as other biomarkers. We expect to be able to share more details on the trial design once these are agreed upon with key stakeholders, including regulatory authorities. As mentioned earlier, we are on track to submit a CTA for this program in the fourth quarter of this year. Looking ahead, our PRISM platform affords a uniquely diverse toolkit with the potential to address a wide range of neurological disorders. Part of my focus at Wave will be to identify additional genetically validated targets and mechanisms that we will pursue in our next-generation of therapeutics discovery programs beyond those that are part of our ongoing collaboration with Takeda. As Chandra shared earlier, we are generating exciting proof-of-concept data for ADAR editing in the CNS, presenting us with a new therapeutic approach that will allow us to explore an array of exciting opportunities in neurology. And while we are not disclosing specific targets or programs today, we are incredibly excited about the future of our neurology portfolio, and I encourage you to watch this space. With that, I'll turn the call back over to Paul for closing remarks. Paul?

Thanks, Ken, and thank you, Chandra, for giving us an update on the tremendous progress within our platform. I would like to conclude by reemphasizing how much we've learned over the past 8 years, and how those learnings have shaped the platform and discovery and preclinical programs we are bringing forward today. The capabilities of PRISM enable us to unveil the potential of PN chemistry and the impact of adding these modifications to the backbones of our therapeutic candidates. We have unlocked at our editing a new and exciting modality that we are at the forefront of realizing value from. Altogether, these advancements will enable us to deliver a sustainable platform to feed our pipeline of RNA therapeutics and drive value for all of our stakeholders. And with that, I'd like to turn the call over to Q&A. Operator?

[Operator Instructions] Our first question comes from Joon Lee with Truist Securities.

I had one question for each program, the PN, ADAR and C9orf72. For the PN, I'm just curious if you have any immunogenicity data, regarding the new backbone, does introducing an unnatural and synthetic backbone cause any immunogenic response? And on the ADAR program, I know that ADAR knockouts are [ embryonic lethal ] and that they're highly active during embryogenesis. But what's the role of ADAR in adults? And how broadly is it expressed to be a therapeutic utility and what would be the consequence of diverting away ADARs from their normal activity to function editors endogenously? And on the last question, actually, I'll just stop there. I'll just hop back on the queue.

No worries. And it's good that we're keeping track of it. So with the first question as it relates to PN chemistry. And I'll hand a lot of these questions over to Chandra, but just to frame it, I mean, the work on chemistry that we've been using on PN, as we mentioned in our presentation, it's been integrated into a number of programs with which have high IND-enabling studies or CTA-enabling studies underway to support those submissions. And as we said earlier as well, have been incorporated into our exon 53 program, systemically, which we've used in -- as we said last year, have been planning to submit a CTA for before that we had discontinued suvodirsen. So we have an extensive support going forward. Obviously, safety is something that has to be assessed in the clinic. Chandra, do you have anything you want to update on as it relates to the PN chemistry modification specifically? And then we can take Adar as a separate subject.

To add to your point, PN chemistry, what we're using is very judiciously pacing in a few places. And these are, again, usual back bone. So the toxicity, to Paul's point, the toxicity and the immunogenicity is all looked up as a whole molecule with a different backbone chemistries. So it's not just a pure PN molecule.

I think the follow-up -- and just follow-up on that point, it's a great one, Chandra, because I think, Joon, this is one of the advantages that I think, as we've said from the very beginning, in characterizing single drug, is that we are able to characterize the whole molecule. So with the incorporation of the PN modification itself, that modification is also [ carly ] controlled. So we're still assessing each molecule, and we do evaluate immunogenicity of a molecule on the totality at that medicine. So we're able to still do those assessments individually. So you wouldn't expect to see that as a unique feature of the PN chemistry itself, but we continue to be able to assess it in the totality of the molecule. Did it answer your PN question? Then we can shift to the ADAR question.

Yes, yes, yes. That was very helpful. And then on the ADAR, I'm just really curious about what it does normally why -- and how you would...

Yes. Okay. The first question is probably an immunogenicity question too on here. I want to say that by using the endogenous system, you don't have the immunogenicity characteristics. So there's a number of components that are being explored with others that are putting in a new engineered enzyme. So by not having to ingenuity enzyme, to Chandra's earlier point during the discussion, is by not having to engineer it, there's not immunogenicity associated with the endogenous enzymes.

Yes, absolutely.

So [indiscernible], you want to -- your other questions, Joon, I just want to make sure I have it is on how to engage it away from -- you said ordinary function and just being able to utilize?

Yes. Just a -- little I know about ADAR is that they're important embryonically and they're lethal, if you don't have it, but how active is it in the adults -- in patients -- in adult patients that you hope to achieve a therapy effect in? And also if it is, actually broadly expressed, what would be the consequence of hijacking ADAR, thereby diverting them away from their normal function? And what would be the safety consequence of that in your thought?

I mean -- yes. I mean, just to take some of that on. I think as we approach this, again, safety [ is any therapeutic ] is something that has to get assessed clinically. I think being able to utilize it, it is expressed. Obviously, there's different ADAR enzymes that are in different tissues. I mean ADAR enzyme we're using has a broad distribution associated with it, which helps us get to a number of cell types that we can utilize. I don't look at it as necessarily high jacking it, but at least using it, and using it for an intended consequence of editing, to date hasn't shown any detrimental consequences. Obviously, there's a lot more work to be done in terms of clinical translation. But we're pretty excited by the fact that across species, as Chandra alluded to in this presentation today, both at the nonhuman primate level of editing in vivo and in a proprietary mouse model where we could assess it. In both circumstances, we've been able to look across the class. So it's still transient in the sense that we're not permanently hijacking, just to use your words, the enzyme. So there is this kind of ability to use it, edit it and that transient feature is great. And that's another reason why we've stayed away from, kind of, using viral vectors and other approaches to use it. And therefore, like any of the therapeutics, we can titrate the oligonucleotide to drive that intended effect. Does that answer?

Yes. Yes, absolutely. And what's your intellectual property around this? Obviously, you -- ADAR is endogenous. So it seems like anyone who has the ability to take advantage of endogenous ADAR could maybe potentially go and do ATG edits, which is about 50% of the diseases as you present. But how are you differentiated from potential other RNA editing companies that are out there? And I think there are a few, but I'm just curious your thoughts there.

Yes. I think one of the advantages our focus as it's -- in all of the categories we're going after is on the medicine. The molecules themselves. So you're right, the enzyme itself is endogenous, but because we're not doing something around engineering a new enzyme, but utilizing the endogenous enzyme. You're right, we're able to focus and train our intellectual property, but more importantly, our drug discovery and development efforts on the molecule itself. So our intellectual property is built around how we build the molecules that are themselves able to engage the enzyme and to promote other things. In the same way, we would do that in engaging RNase H for antisense media silencing Ago2 for RNAi silencing, splicing, et cetera. So we build the IP around how we build molecules.

Our next question comes from Paul Matteis with Stifel.

This is Alex on for Paul. Just a couple of questions on the new phosphoramidite backbone chemistry here. I guess I'm curious if you have any thoughts on, kind of, why this backbone seems to be better. Does it have to do with charge? Are the molecules getting into cells better? Is it sort of a geometry thing? Are they more rigid how is that happening? If you have any thoughts there, that would be helpful. Also, related to that, I'm just curious, like, when you're looking at a sequence comparison between the PS/PO and PS/PN combos, not -- it doesn't seem like PS/PN is always better. So I'm curious if you're really confident that the PN is really having that benefit all the time? And how you're thinking about all of the different sequences you could test as you're trying to optimize which sequences to go after?

That's great. I'll turn the call over to Chandra. But I think we've pretty much [indiscernible] extensively when we've done rank ordering of compounds, and there's always variability in screening. But when you look at the PS to the direct comparator of the addition of PN, in both the silencing applications as well as in splicing. So both in down-regulating and up-regulating, we see a direct comparison of what that gets us in terms of benefit in both approaches. I think what's really unique, and I think will be exciting is Chandra explaining the work that's underway in understanding PN chemistry. And this is very much a work in progress. I think we're excited by data we're generating and excited about what we're continuing to learn in the innovations. Chandra, do you want to share more about your thoughts around PN chemistry?

Yes. Sure. So the PN chemistry, to Paul, adding to Paul's thing, this is neutral. So what we always was interested in is that when we were using stereopure constructs, we saw these things taken up so rapidly by ourselves. So the next question we asked was okay, what do we introduce? Neutral backbone, so you break up some of the charges and then you try to explore more on the chemistry side. So when they did that, we saw this uptick was rapidly enhanced, and I showed that in the slide. So what we think is that it's a combination of charge, stability and also, to your point, about some of the confirmational changes that can actually help us to penetrate to the south and to travel through the cells. So again, some of the things we understand very well and some of the things we're still in the exploration mode. So we'll be publishing some of the data fairly soon. So -- but it's pretty exciting to see the addition of a couple of the PNs changes the whole profile of the molecule.

And then to Chandra's point, just to add it, it is about the concept of rational drug design. It is about, as Chandra said, the judicious use of where you put that. And as we built our intellectual property estate, both on the modification itself and where and how you use it, one of the things that had been explored is that the complete use of PN modifications actually yielded some optimal results. So it's not about just creating all PN. And I think this is really the value of what we've been able to unlock from the very beginning in the value of what studying single medicines gets us. And anybody who was at Research Day in 2019, can remember, Greg, our co-founders, reminding everybody that you can't optimize a mixture. And I think this is really the testament to how you create continued optimization in rational drug design. As to the benefits of a new modification is about where you put it. And I think we're excited about a lot of the work we're doing in terms of seeing this exposure. I think where we are today and which is exciting is we see it in multiple in vivo models, whether we're looking at the central nervous system, whether we're looking at muscle, whether we're looking in hepatic, and we're seeing it across multiple modalities, antisense RNAi, exon skipping and ADAR editing. So I think as we look at the totality, we're really excited about the movement we made with good in vivo modeling that then lets us help think about dose exposure and ultimately clinical translation, which is where we are today and thinking about a number of clinical and potential clinical programs that we're moving forward in our pipeline.

Our next question comes from Salim Syed with Mizuho.

Just a few for me, if I can. And hopefully, I'll have a question for everybody here. Paul, maybe just strategically, with regards to the PN chemistry, I couldn't help to notice that there was some mild blast data in mouse muscular discrete data for the PN portion of the slides. Is there any intention at all to use the PN chemistry to get back into DMD? And then also perhaps apply this to SNP1 and 2 for HD? Second question is on ADAR. Chandra, curious why -- just starting off with hepatic, was -- what's the back story there? Because I noticed you mentioned quickly into neurology. So why is hepatic the first indication here? Is there any link to move to neuro for that hepatic start and is that a commercial indication? Or is this something where you need it to get into neuro? And then also, what does quickly into neurology mean? And then just lastly, for Ken, Ken, I was curious why for the exploratory you using ALS-FRS and not ALS-FRS-R, which, if I recall, from the September 2019 FDA guidance specifically calls out the -R is perhaps better measure to use from the FDA guidance?

All right. So I have to listen in. So we'll start with the -- your exon 53 question, and then we'll move to ADAR hepatic and then Ken's question around the ALS. As it relates to exon 53, I mean, obviously, today's data and discussion was focused, and I think it's really important on understanding PN in the context of splicing. So I appreciate that, but I -- there is a combination first emphasis, and while it was extensive around myoblastic studying the impact in a really severe phenotypic model, it really gave us the ability to study what happens when PN chemistry and how does it access muscle tissue. Now we have profound results in a way that was extraordinarily exciting and gives us reason to be excited about the exon 53 molecule that did include PN chemistry. We are revisiting the 53 data, but we're exploring potential collaborations to advance the program. So there's a thought. We're not going to ignore the data that's driving it, but we're also proceeding in a very cautious way. As it relates to ADAR and, I'll hand it off to Chandra, but I think it's important that when you explore new molecules, one of the questions that we had with ADAR was by using GalNAc, we could target a specific cell types. And so I think there was kind of an initial approach when you're kind of building the SAR and building the understanding of individual molecule, to really -- to give it in a way to assess it in vivo, and in this case, particularly in NHPs. And so GalNac obviously leads to hepatic. I think you also asked a question around the commercial target and how we're thinking about it. Absolutely. I mean, we are thinking that if we are developing a potential molecule that we do think about a substantial indication in a way that also is not just about doing something that one can use doing a different modality. But really a target where we can explain why we would specifically utilize a correction mechanism versus, let's say, a silencing mechanism with GalNac. So that really drove us in terms of; one, hepatic, but two, we're thinking about within hepatic, where it's not just fast following another approach to silencing, but working on a disease whereby correcting gives us a unique insight, unique advantage in that target space. Chandra, I don't know if you have anything you want to add, and then I'll hand it off to Ken to answer the question around ALS.

Yes. So I can add to something like that. Expected levels of ADAR is also high in the liver. And so we can -- we also had all the infrastructure to understand about editing using primary hepatitides. So when we were evaluating the platform to show that endogenous ADAR can be added so as we found it actually very useful to look at it probably first in hepatocyte. And GalNac, of course, GalNac can deliver. So if you want something as a proof of concept, it was a very well suited place for us to try initially in hepatocytes. So now we got the confirmation, so we can now jump into other tissues. Again, ADAR is ubiquitously expressed in all the tissue. So that's where proof-of-concept was really our primary focus initially. But to Paul's point, we also will announce the target by the end of this quarter or sometime in 2020.

Just to add in follow-up because you also bundled into that question, Salim, I think a CMS question around just ADAR and in the central nervous system. And I think given that the enzyme that we're targeting is also present in those tissues that led itself nicely to continue that exploration in a non GalNac context. So obviously, the data we have today excited about, not just the in vitro editing in various cell types in the central nervous system. But also within the in vivo data that we just shared, gives us directional confidence that there's -- we can get exposure and develop drugs. I'll hand off to Ken to give a little bit of context on how we're thinking about that in neurology. But also to continue on the answer to your last question that related to the ALS topic.

Yes. So maybe I'll take the last question first, which is about ALS-FRS in our upcoming C9 trials. And I think we are using the ALS-FRS-R. I think the -R must have been left off the slide. But I think suffice it to say that our intention is to follow the latest guidance in our clinical development program. For ADAR and CNS, I think quickly is a relative term, but there was a fair bit of really interesting work going on with ADAR and CNS targets when I joined wave a few months ago. And as I become more familiar with the technology, we started to look more broadly at potential ADAR targets. And that process is ongoing, but moving very quickly. And so we hope to be able to talk about specific programs in the very near future.

Just to round out, I mean, I think the excitement around what is achievable with ADAR editing opens up unique target space. And I think the reason we started delivered GalNac was one reason, but not the least of which are a number of really compelling opportunities in that space. So I think as we look uniquely about building a genetic medicines toolbox that has the capability of going and expanding across multiple therapeutic and disease areas. I think we've built that capability in-house and are excited to continue to share that data as we progress.

Our next question comes from Debjit Chattopadhyay with H.C. Wainwright.

This is Aaron on for Debjit. I wanted to ask, [indiscernible] the ADAR editing program, primarily in changing pathological individual mutations, which I could see being a challenge in identifying a large reputable market, for a largely shared new patient? Or is there also opportunity that you're looking at to knock down or even enhance the expression [indiscernible]?

The line was definitely breaking up as you were speaking. But I'll just -- if we don't answer your question, let us know, but I think you're highlighting that there are unique number of approaches of using the editing piece, whether it's around correction, inducing stop codons. There's a variety of ways to think about using it to -- in a variety of different categories. I think initially, and again, to kind of distinguish it from silencing applications. And I think that's what's unique about our opportunity is we've got great tools to do balancing where we need that and utilizing expression. I think the idea of using ADAR has an opportunity to correct where there are unique opportunities like we're exploring in liver, where there are areas where down-regulation is important and others where up-regulation is important and really viewing it as how do you correct and correction being a different application than silencing.

[indiscernible]

It will become more clear as we think -- and we're happy to spend more time, and I think we did earlier in the presentation, kind of, laying out this, kind of, multitude of ways of thinking about that because I do think there are opportunities around that correction space. And as we think about the first target in hepatic, we'll be sharing more around that target that I think we'll put it in a lot more context is how we're thinking about correction. But the target space is pretty vast. And I think our first approaches are ones where it would not be ambiguous why we would choose this approach for that target.

Okay. Great. And then for the C9 program, why is it starting in [ ex U.S. ]? And what would you need to begin an active IND?

Well, given that we've not yet announced the final filing, I think we're not guiding to geography. I mean, I think we have full intention as we think about ALS as a critical disease of patients everywhere. I think we're looking at part of the global study. So there's nothing imminently now that would say preclude us from being in the U.S.-based on anything we think.

Our next question comes from Mani Foroohar with SVB Leerink.

A couple of quick ones. Although, fewer than the 37 than Joon had. In terms of drug delivery, can you talked a little bit last year around the value of backbone chemistry and some sort of machine learning technologies that you guys have when you think about improving cellular delivery. Can you give us a sense of how what you've learned from your experiences with suvodirsen hunting the interim data, et cetera, how those informed how you think about your delivery tools and how they might be applied to this new technology. And then beyond that, obviously, this is -- a lot of the expertise that you've built thus far applies here. Are there additional investments that you expect to be making around development and manufacturing infrastructure, specialized expertise you expect to bring in on the human capital side and how you think about the timing of those investments and build out as this technology continues to develop?

So the great news is when we're talking about enhancing delivery, we're not doing it via the need for building out new conjugate. The thing about building a new antibody conjugate its required build-out of antibody manufacturing. So the benefit of what we've done today is really a continuation of what we started at the very beginning, which is to build a world-class nucleic acid discovery engine that's capable of taking constant learnings and applying them and seeing where those advantages are. So the good news is it all leverages our existing infrastructure, our existing talent and our existing manufacturing competence so our GMP facility can manufacture the PN molecule. And this is really a testament to the fact that if you remember as we're moving into the latter part of last year, we were prepared to manufacture an exon 53 molecule. And so we've already built that manufacturing capability within our existing facilities. So there's no additional requirements or investments required to utilize PN chemistry. We've also been utilizing it as we've advanced our C9 program, our SNP3 programs. This is not something, again, today that we're saying it's going to be forward needing to be built out, but something that we've invested in and have already begun to realize that translational value. It's interesting because when we say delivery, there's a lot of different contexts that people think about delivery, oftentimes, it's around having this, kind of, conjugate strategy. And we talk about delivery, another way of thinking about it is accessibility. How do we see increased accessibility of cells and tissues with the modifications we're imparting. And I think that was the learning. And when we talk about machine learning, one of the things we've done is we've generated hundreds on oligos, the idea of being able to make drugs move those chemistries around it and have those be single medicines. So now the richness of the data sets that we're getting each time we look at a molecule, we're able to understand where do these molecules need to be placed in order to drive that efficacy and then be able to use that across multiple programs. As we said, we've been incorporating this chemistry into C9, SNP3. That's incorporated in our collaboration with Takeda. We're getting multiple programs that we're able to assess this with. And the data that we've generated in muscle was profound when we've shifted to the addition of PN chemistry in terms of exposure into muscle. And then we know that exposure is a key ingredient, hence, being able to reduce the doses substantially and being able to look at that exposure level. So I think we need to think about it as PN delivery just because I think it makes people think of a vehicle to deliver, whether it's LNPs or other stuff. That's not the approach that we're taking. It's enhancing the chemical backbone to enhance cellular uptake tissue uptake so that we can look and see differential outcomes with these medicines.

Our next question comes from Eun Yang with Jefferies.

Paul, I think you guys [indiscernible] the presentation, you guys touched upon this, but I want to specifically ask you a question. So when you look at your prior DMD exon 51 program, preclinical data was a remarkably good rate. It's very good, and it just didn't translate into humans in the clinical study. So would it be the PN chemistry with those attributes that you guys talked about, how do you think that it's going to help you -- help translate into better human outcome, chemo clinical testing results?

So I mean -- and I appreciate the question, Eun because I think the data that we show today demonstrates the impact of a PN backbone change. So changing the fundamental structure of the drug. When all the other variables are kept consistent, and we see an advantage. So we see an advantage both in terms of potency, and that relates to dose, so that even in vivo studies that we're doing now at a substantially reduced dose. I think the DKO, for us, was a very helpful model to understand this because it gives us a model that has a phenotype, I mean it has a severe phenotype in terms of spinal. So we have to, kind of, overcompensate on that. So I think the expansion into both new models as well as the advancement of new chemistry continues to give us insight. I think when we look at things from a very scientific point of view, I think what we take in every opportunity is an opportunity to learn, whether it's on clinical data or preclinical data. And I think that the team is always looking to answer questions and to derive understandings and differences. And I think the amount of work we've done in prosecuting how to advance PN chemistry has us excited. Not just looking at splicing, but as we look across the board, most recently with C9, where as we look out with the new durability data on silencing the DPR, the peptide, being able to see data out at 6 months and self-sustained knockdown. So I think there is a uniqueness in what we've built in terms of the chemical backbone that just continues to build on what we built fundamentally on the platform.

Okay. And then with the new PN chemistry and ADAR programs, does that open up more opportunities for potential partnerships going forward?

No. I mean, thank you, Yang. I mean, absolutely. I mean, I think what we've demonstrated today is whether we talk about various modalities, so moving in antisense RNAi, exon skipping, ADAR, and being able to utilize those across multiple therapeutic areas outside of neurology. Because I do think we're excited about building out our neurology franchise using a multimodal effort. But we've got tremendous opportunity. The data that we showed, and that was why it was important for us to look at muscle gets us extension in the heart and other tissues that gets us beyond thinking about just exon skipping in DMD, but thinking about opportunities much more broadly. Same thing as we think about the liver and the opportunities to think about the hepatic space in a very broad way and multiple tissues there. And as we've had a number of conversations that have been going since sharing this information, I think the conversations are fastening because I think we offer is the ability to think about multiple tools. As we think about some of the ophthalmology data we've shown, being able to think about working in the ophthalmology space. Where you have both tools of silencing and editing open up a tremendous universe. So I think what we're able to do both to commercial partners, but also academic partners in terms of getting chemistry and exploring new target space that can be unlocked that hasn't been able to be unlocked before, really lets us explore partnerships in a variety of ways, expanding data sets and also expanding commercial opportunities for Wave.

And our last question comes from Yaron Werber with Cowen.

This is Brendan on for Yaron. Just a couple of quick ones from us. I actually really want to focus on the C9orf72 program. Can you just quickly, kind of, give us a sense of how solid the clinical assays are to detect the repeat containing of C9orf72 proteins in the CFF and also the wild-type protein separately? Are these, kind of, pretty well established? Or you think it's going to require a little bit of optimizing, like, in HD program? And also, do you expect any kind of notable differences between the 2 indications, given that one is clearly more spinal cord centered and the others looking more at higher brain regions? And then I guess, just the second question really quickly. If you have any idea, if you can, kind of, let us know if there's -- just regarding kind of kinetics between the C9 knockdown and some of the biomarker changes, kind of, how long you would anticipate? Is it, like, pretty quickly that you would think that, given the mutant containing transcripts, and you'd see pretty substantial changes, in say, NFL or some of the other ones?

This is Ken. Thanks very much for the question. So I think the assays for measuring the Poly(GP) dipeptide repeats are very well-established and can be readily applied to our clinical program. There's not currently a widely used assay, quantitative assay for measuring the C9 protein. And so that's something that will require some development, should we choose to try and measure that in the clinic. I think what we've seen preclinically is that the candidate can access all parts of the CNS that are required for activity in both diseases. And so I don't know that we would expect to see any differences, a priority with regard to activity in either ALS or FTD. And I missed the last part of the question.

I think the speed of effect, I think, was one of the question.

The speed of effect. Yes. So the -- if you look at the data we showed, what you see is onset of action is actually quite rapid. But it's also quite persistent. And I think the recent data we've generated showing pharmacodynamic response being sustained out to 6 months in the mouse really gets us excited about the potential for a prolonged dosing interval in patients, which I think the patients would certainly appreciate.

I think there was one last question around FTD and ALS and similarities. And I think based on literature.

Yes. I mean, they're clearly a spectrum of disease from kind of pure ALS to pure FTD and then a range of clinical presentations in between. And I don't know that we would expect to see any strong differences in activity throughout that spectrum. I think the molecule would work equally well in either disease.

I think the Poly(GP) level is the same. So I mean, I think the idea of looking at those both and running that experiment, why we're excited to approach both indications simultaneously. I think a lot of the way as we think about it for C9 is an analogous way to some more of, like, an oncology focus to go after the genetic target. More so than what the phenotype is, recognizing that you have these, kind of, multiple phenotypes. So if we can develop our drug at the front end of thinking about it as C9orf72 targeted therapy then we target those diseases that have that mutation. So again, a different way of thinking about some of the CNS diseases that are -- can be genetically stratified.

This concludes the question-and-answer session. I would now like to turn the call back over to Dr. Paul Bolno for closing remarks.

Thank you, everyone, for joining the webcast, and thank you to everyone at wave for their hard work. We look forward to connecting with many of you after this call. Have a great day. Take care.

Ladies and gentlemen, this concludes today's conference call. Thank you for participating. You may now disconnect.