Good morning and welcome to Wave's 2021 Analyst and Investor Research Webcast. The slides that accompany today's presentation will be available in the Investors section of our website at www.wavelifesciences.com following the webcast. Before we begin, I would like to remind you that management may make 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 ks for the year ended December 31, 2020, and our quarterly report on Form 10 Q for the quarter ended June 30, 2021.
We undertake no obligation to update or revise any forward looking statement for any reason. In the room with me today are Doctor. Paul Bono, President and CEO of Wave Life Sciences, who will begin the presentation this morning with opening remarks. We also have Doctor. Chandra Varghese, Wave's Chief Technology Officer, who will be discussing Wave's Prism platform and progress towards building a best in class ADAR editing capability.
Followed by Doctor. Ken Rose, Senior Vice President, Therapeutics Discovery, who will discuss ADAR editing in the CNS. And finally, Doctor. Paloma Giongande, VP of Discovery Sciences and Biology will present an update on our Alpha-one antitrypsin deficiency program. Following the presentations, we will open the call up for Q and A.
I'd now like to turn the
call over to Paul. Paul?
Thanks, Kate. Good morning, and welcome to Wave's 2021 Analyst and Investor Research Webcast. We're excited to share with you today the recent progress we have made on our Prism platform and how we are applying that to new targets with the ultimate goal of advancing life changing treatments for patients diagnosed with genetically defined diseases. Today, we are participants in a genetic revolution where breakthroughs in understanding the human genome and how mutations drive disease pathology have provided enormous opportunity to make an impact for millions of people and their families. There are more than 6,000 known genetically defined diseases that are driven by mutations in single genes and new genetic links to both rare and common diseases will continue to emerge.
Advances in genetic testing have enabled more rapid identification of patients with specific mutations who would be eligible for genetically targeted treatment. So this begs the question, if we know the genetic cause of 1,000 of diseases and how to rapidly identify likely responders, then what is the bottleneck to bringing more disease modifying solutions forward? The answer is up to 85 percent of genetic diseases are beyond the reach of traditional treatments. At Wave, we are building a leading genetic medicines company focused on harnessing the endogenous machinery in our bodies to drug the transcriptome, thereby modulating the expression of faulty genes. By intervening at the RNA level, we can design therapeutics tailored to address underlying genetic drivers of disease with an opportunity to achieve potent and durable effects within frequent adjustable dosing.
We can take advantage of simplified delivery strategies, leveraging free uptake and endogenous enzymes to avoid delivery vehicles. RNA targeting therapeutics have an ideal balance of precision, durability, potency and safety, as well as a clear line of sight to commercialization with established regulatory access and reimbursement pathways. Our focus on the transcriptome goes hand in hand with a fundamental truth that the biological machinery to address genetic diseases already exist in ourselves. It just needs to be controlled with the right tools. We are able to achieve this through the rational design highly specific oligonucleotides.
We have built a genetic toolkit comprised of 3 modalities, all with the capability of modulating gene expression by efficiently and precisely harnessing existing cellular machinery. Most recently, we have been able to utilize ADAR enzymes to establish what we believe is a best in class RNA editing modality. You'll hear a lot about this capability today, including how we are applying editing in the CNS and other tissue types. Using ADAR to edit single bases in RNA gives us the dexterity to restore functional protein or even up regulate expression or control how it functions. The ability to access all these mechanisms with one platform enables us to develop the tools to optimally address disease biology.
Our PRISM platform can therefore be summed up in one simple concept, a unique ability to unlock the body's own ability to treat genetic disease using oligonucleotides. Through the lens of stereochemistry and the ability to control the 3 structural features of oligonucleotides, we can design precise tools that work in unison with the body's biological machinery. Again, these are short and fully chemically modified genetic medicines that are either freely taken up by cells or compatible with Galmec delivery. Through Prism, we identify, aggregate, leverage and deploy pharmacologic insights with a deep understanding of the interplay among sequence, chemistry and stereochemistry. We have unique backbone chemistry, including our PN modifications, which positively impact the pharmacology of all of our modalities as Chandra will review today.
Naturally occurring acids are not suitable for use as therapeutics due to a lack of stability. In addition to sugar modifications, backbone chemical modifications, including phosphorthioate, that are used to stabilize different types of therapeutics including antisense, RNAi and guide strengths. With each chiral chemical modification, oligonucleotides. Why is this important? Because chirality matters.
Stereochemistry affects pharmacology of oligonucleotides in vitro and in vivo. Recently others in the nucleic acid field including Alnylam have been following our lead with scientific publications recognizing the positive impact of chirality. We're excited to share more on the impact of stereochemistry shortly. Controlling chirality is core to how we design, optimize and manufacture our therapeutic oligonucleotide candidates. With PRISM, we have the ability to apply this control to every step the drug discovery and development process and we have built a dominant IP position in this space.
While others may assume this could add cost and complexity, we are able to do this efficiently and at a comparable cost to stereo random methods. For nearly a decade, we have been investing in and iterating on our PRISM platform. Our vision is to take genetically defined targets, predict the sequence and apply the therapeutic modality best suited for the biology. We use our platform engine to screen candidates and optimize the pharmacologic profile based on predefined design principles. This process is powered by predictive modeling and our machine learning capability.
With the learnings from each program, we refine and improve design principles and deploy them to subsequent programs. For this reason, the platform today is distinct from the understanding and technology used in our initial programs. The evolution of our platform is reflected in the significant improvements of our hit rates from our screens of silencing therapeutic candidates. Years ago, our hit rates were approximately 10% to 15% with our stereo random screens on par with industry standards. With the application of chiral control to every screen, chemistry enhancements, including PN chemistry and machine learning, we are sustaining hit rates of 80%.
While these reflect our screens for our silencing oligonucleotides, we are on track to achieve similar progression with our other modalities. Additionally, we have 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. We are also applying data sciences to identify and explore new targets with our splicing modality. An example of this recent work that will be presented at the OTS conference this week, our data science team use large genomic data sets to develop a model that identifies exons amenable to exon skipping allogonucleotides. They predicted more than 2,500 potential targets, most of which were previously undiscovered.
From this work, we have identified multiple targets that could fuel new exploratory programs. Our portfolio of Stereopure TN modified oligonucleotide spans multiple modalities, including our 3 clinical programs, WVE-four, our variant selective silencing candidate targeting C9orf72 for ALS and FTD WVE-three, our allele selective silencing candidate targeting SNP3 for HD and WVEN531, our exon 50 3 exon skipping candidate for DMD. We expect to generate data from clinical trials for these candidates through 2022, which represents the 1st clinical data with PN modified compounds. In a moment, Chandra will review our PRISM platform and why we are so excited about these modifications. Quickly evolving editing capability, including an update on our AATD program from Paloma and the application of ADAR editing in the CNS from Ken.
It's an exciting time for nucleic acid therapeutics and we are only just beginning to realize the full potential of our PRISM platform and its ability to redefine oligonucleotide therapeutics. And now I'd like to turn the call over to Chandra Varni's Chief Technology Officer to review our Prism platform and ADAR editing modality. Chandra?
Thanks, Paul. Good morning to everyone on the webcast and thank you for joining. Our Prism platform is built on the reality that there exists enormous opportunity to tune the pharmacological properties of Each of these features can be modulated. We can change the sequence or incorporate a modified base. We can change and innovate on the chemistry of ribose of the backbone and we can control chirality of all stereo centers, including those in the backbone.
We leverage this rich diversity to design molecules with desirable profiles. Wave is uniquely positioned to rationally design our molecules because of our deep understanding of the interplay between these tunable features and our ability to control them. With Prism, we modulate these features to design therapeutic candidates with favorable activity profiles and compressing their potency, tissue exposure and duration of activity. To optimize activity profiles, some of our design principles are universal. For example, with the stability and tissue exposure across modalities.
On the contrary, potency is fine tuned based on the interaction of polygonucleotides and the endogenous enzymes requiring our unique ability to control sequence chemistry and stereochemistry. Since Dave's inception, we have initially generated stereo pure molecules, those in which the chirality at every stereo center in the phosphothiade or PS modified backbone is controlled. Without this control, oligonucleotides are a mixture of potentially millions of different isomerge. Last year, we unveiled our proprietary phospholiguanidine based modification or PN chemistry, which like the PS modification introduces a chiral center into the backbone. We also developed the capabilities to control the chirality of these PN linkages in order to fully integrate PN chemistry properties to our stereo pure molecules.
Because it is neutral, it even breaks up the negative charge on the backbone and we believe that this property drives tissue exposure benefits. Oligonucleotides with GN backbones retain complementary base pairing properties and consequently it retains the resulting specificity inherent to these molecules. In the last year, we have shown you many examples of how the addition of few judiciously placed PN linkages into our oligonucleotide backbone has positively impacted the pharmacology of our molecules. What has been truly remarkable and differentiates this modification is the magnitude and consistency of benefits we see regardless of the modality, splicing, silencing or editing. I'll review several datasets that demonstrates this impact on potency, tissue exposure and durability of our oligonucleotides on the coming slides.
On Slide 20, we show how the interaction of just a few rationally placed PM linkages provides a notable potency benefit across modalities in vitro. On the left, we compare a series of stereo pure silencing molecules that act to an RNase H dependent silencing mechanism with PS modification shown in light blue or with a few PN modifications shown in dark blue. Across multiple sequences, we observe a downward shift indicating a potency gain for this modality. In the middle, we compare a series of splicing molecules with PN modifications or with a few PN with PS modification or with a few PN modifications. Across multiple sequences, we observe an upward shift indicating a potency gain for this modality.
On the right, we illustrate the dramatic improvement in both potency and maximum editing driven by the application of Stereopure PS and PN backbone modifications. I will provide more detailed updates on our editing capabilities a little later. Importantly, these potency shifts with PM chemistry in vitro translate in vivo. Here we show PKPD profiles for 2 molecules from our C9OR of 72 discovery efforts. These PFPO and PM containing silencing molecules engage RNA SeH to decrease pathological C9orf72 transcripts and they illustrate the potency and tissue exposure benefits that we observe with TN chemistry.
The graph shows exposure on the x axis and mRNA expression on the y axis. The PM molecule shown in dark blue shifts rightward indicating increased exposure and downward indicating increased RNA silencing compared with the PSPO molecule of the same sequence and same chemical modification pattern. Now for the splicing modality, we highlight 2 examples from our DMD discovery efforts that illustrate that meaningful biological benefits can be realized with the addition of a few PN backbone linkages. The graph shows data from a survival study we performed in a double knockout, our DKO mouse model for DMD with an aggressive and lethal phenotype. In these DKO mice, treatment with 1 of our PM containing exon skipping compounds shown in green led to a 100% survival for the duration of a 40 week study when administered at a 75% lower dose than the PS modified molecule shown in light blue.
In a separate 6 week experiment, in the same DKO mouse model, the PM containing molecules accumulated to higher levels in all muscle types compared with the PSPO oligo as shown on the top of the slide. The PN molecule also led to more exon skipping and more dystrophin restoration in all muscles evaluated. These differences are most dramatic in the diaphragm and heart, which likely explains the performed survival benefit observed in these mice. They have also applied our Stereopur PSPN modification in another silencing modality RNAi. To engage the RNAi pathway, we use double stranded siRNAs.
These molecules engage with AIGO2 with the guide strand loading onto the enzyme and interacting with the RNA to form a substrate that is cleaned, ultimately leading to the degradation of the target RNA. To study our saRNAs, we benchmarked our molecules to reference molecules from the literature that are well studied in ESE and advanced ESE format. We then generated double stranded GalNAc conjugated siRNAs targeting transparitene mRNA or TTR. Because TTR protein is secreted into serum, we can track levels of TTR protein in serum over time in the same mice. Both control of stereochemistry and application of PN chemistry drive a threefold increase in potency, 2 fold increase in durability of effect and an unprecedented 35 fold increase in AGO2 loading as compared to reference EFC.
Then we applied PRISM to the state of the art RNAi design based on an advanced EFC chemistry. We again observed a significant benefit from the molecules containing PM chemistry shown in dark blue with a 50% increase in duration of activity after a single dose of 1 week per kg compared with the reference molecule shown in black at the 2 month time points. We're excited about these data because they highlight that stereochemistry and PN chemistry enhance pharmacology of yet another oligonucleotide modality, this time one relying on double stranded RNA. Now with PRISM, we leverage the full diversity of nucleic acid chemistry, including diversity resulting from stereochemistry to optimize our molecules. This enable us to understand structural activity relationship or SAR, which is the standard practice in the industry for all types of modalities, including small molecule and antibiotics.
The oligonucleotide space has ignored this diversity for decades, missing out on an entire dimension of therapeutic optimization. Thus far, I've highlighted how we use Prism to optimize potency and duration of activity. Through PRISM, we are also able to identify and adjust for the impact of stereochemistry on the tolerability of our molecules in vivo. I'll walk you through 2 examples where we show the dramatically different profiles for closely related stereo isomers, enabling us to tune tolerability while maintaining potency by selecting the right isomer. In the first example, we highlight 2 GalNAc conjugated molecules that promote RNase H dependent silencing of a liver target.
At the top of the slide, we illustrate 2 stereo isomers that are identical in design, except at a single stereo center. As seen in the graph on the left, these 2 isomers have comparable activity against the target mRNA in vivo. By contrast, the graphs in the middle and to the right show how they differ dramatically in tolerability with isomer 1 leading to a significant expression of multiple tolerability markers, including liver enzymes, ASV and ALT and TNF receptors that induces apoptosis. By contrast, isomer II does not induce significant expression of any of these markers. In the second example, we highlight molecules that promote RNA stage dependent balancing for an undisclosed CNS target.
At the top of the slide, we illustrate 2 stereo isomers that only differ at 3 stereo centers in the backbone. Once again, as seen on the left, these isomers have comparable and potent activity against the target mRNA in vivo. They again differ in how well they are tolerated with the isomer 2 leading to a dramatic and significant body weight loss beginning almost immediately after treatment. By contrast, mice treated with isomer 1 gain weight comparably to those treated with PDS. For these examples, we have ignored if we had ignored stereochemistry, we would have either selected for a mixture containing isomers with unfavorable profiles with potential risk for tolerability issues emerging over time.
Or these isomers may have driven us to avoid this target sequence and potentially sacrifice potency. By controlling stereo chemistry, we can design around tolerability signals without compromising potency. With our Prism platform, we applied novel chemistry and unique design principles across modalities to truly innovate on oligonucleotide discovery and development. Our Stereopyr PS and PN backbone modifications represent a breakthrough in the nucleic acid field. 1 of the best ways to demonstrate this is to discuss how we leverage Prisam to develop our RNA editing modality.
We were inspired by early academic publications in the field demonstrating that oligonucleotides can lead to RNA editing with endogenous ADAR dating back to Todd Wolf's publication in 1995. We took early structural insights into ADAR RNA substrate interactions and initiated our work on this modality with the aim of expanding our capabilities to include editing all through free uptake of chemically modified oligonucleotide. We evaluated more than 1,000 ADAR Oligon Nucleotides to produce new insights into the relationship between the molecule structure and its ability to elicit robust ADOT editing activity. What was most exciting, it was not until we applied chiral control and PN modifications to our oligonucleotides that we saw the strong potential for this capability enabling us to rapidly progress to demonstrating efficient in vivo editing. Today, we are introducing our AMESH, short chemically modified oligonucleotide to recruit endogenous ADAR enzymes to change a specific adenosine or A to inosine or I, which cells read as a guanosine or G.
For the rest of the presentation, we will refer to our ADAR editing oligonucleotides as AMERSH. A2i editing is a common post transcriptional RNA modification that generates transcriptomic diversity and the ADAR enzymes are ubiquitously expressed across tissues. We are at the forefront of this modality defining new levels of editing that can be achieved as well as the tissues and cell types amenable to this approach. I'm excited to have the opportunity to share more with you today. I'll start out with how ADAR expands our toolkit to address diseases with RNA therapeutics by enabling protein restoration, upregulation and even modification of protein function.
Next, I'll describe how we design, optimize our AMOS, which differentiates us from other editing technologies. Last, I'll discuss how we have built our success with our GalNAc conjugated AMERS and to use our unique chemistry to expand beyond editing in the liver. Nearly half of known pathogenic SNPs are G2A mutations. Many of these are loss of function mutations. The unique ability of ADAR to correct these mutations and to restore protein expression creates significant opportunities for us to potentially treat a broad spectrum of human diseases.
Later in the presentation, Kennen Paloma will walk through our data supporting how we use this application on the therapeutic targets, including restoration of functional protein to address alpha-one antitrypsin deficiency. The application of PRISM to RNA editing opens the door to therapeutic applications extending beyond the restoration of protein function. We can use ADAR to upgrade protein expression, to modify protein function by also in post translational modifications or protein protein interactions or to alter protein stability. Ken will share data on an example of this later on. Now, I'll highlight how we apply our unique capabilities to design and optimize AMOS.
Each of our AMOS have several consistent features. They're single stranded oligonucleotides that are typically 30 basis or fewer. They're fully chemically modified, including modified nuclear bases and stereo pure PS and PN backbone modifications. They are able to be conjugated to ligands to aid in tissue targeting. By utilizing our unique chemistry platform, we can rationally design A MUSH for each target to efficiently recruit ADAR to maximize editing.
Here, we show the activity of GalNAc conjugated beta actin stereo pure AMR with and without PN linkages and compared to the matched stereo random control shown in black in primary hepatocytes. The addition of PN chemistry substantially improves both potency and editing efficiency. We have confidence that the endogenous ADAR editing capacity of a cell is sufficient to support therapeutic ADAR editing without disrupting homeostatic ADOR activity. In the graph, we highlight editing levels observed in 3 transcripts when we evaluated editing for each transcript in isolation shown in light blue or when all the 3 transcripts were targeted in the same experiment in the same cells in the same time shown in dark blue. Under both conditions, editing levels of each transcript are almost the same, suggesting there is ample reservoir of ADAR editing capacity for us to tap into.
A challenge for ADAR is the defined sequence phase of the target. To navigate this, we have evaluated sequences complementary to the ERADIS side as one dimension of a rational approach to designing AMOS. For this investigation, we changed the sequence motive on the AMR independently of the sequence motive in the target in over 300 AMR. This heat map shown on the right of the slide reveals a clear pattern in the design that helps us define the sequences in our AMERS that support the most robust editing. And datasets like this example enable us to predict sequence design in our AMERS to optimize for editing.
We have developed AMIRS, the direct editing of multiple endogenous transcripts. This graph highlights editing at 8 different targets. These observations helped build our confidence that we can develop an editing technology that with some optimization to the target can be applied more broadly. Next, I will show how we translated RNA editing in vivo. In this section, I'll highlight the work we have done to establish proof of concept in vivo in multiple tissues, starting with GalNA conjugated AMERS in liver and expanding to CNS, ophthalmology and beyond.
It is important our AMRs are optimized for human ADAR. While we have demonstrated editing in non human primates, we know some diseases targets some disease targets will be unavailable in non human primates to evaluate in vivo target engagement. As such, we developed a transgenic human mouse ADAR mouse with human ADAR, which expresses human ADAR in liver and neurons at levels that are equivalent with human tissues as shown by the western blots on the right hand side of the slide. This model enables us for the assessment of in vivo target engagement with human ADAL and is especially important for disease targets that are unavailable in non human primates. Now I'll start by reviewing the success we have had with GalNAc conjugated AMESH to achieve highly specific automated editing in liver with subcutaneous administration.
As we have previously described, we achieved efficient RNA editing in vitro with GalNAc conjugated AMOS across a variety of cell lines, including non human primate and human primary hepatocytes. We then moved in vivo dosing non human primates subcutaneously once a day for 5 days with 3 chemically distinct AMOS. We detected up to 50% editing as compared to a baseline at an initial time point, which was remarkably durable out of 45 days post last dose as shown in the middle of the slide. We also determined that these amers are highly specific. We performed full transcriptome RNA Seq in primary human hepatocytes.
We only detected editing at the target sequence in the acting transcript and observed nominal off target editing across the transcriptome as shown on the right. These results drove our decision to initiate our 1st therapeutic program with GalNA conjugated AMOS for AATD. Now building on our progress with GalNAc Conjugated AMERS, we then explored unconjugated AMERS to CNS and eye. As Ken will discuss later on, these data have led us to our MECP2 discovery program and undisclosed exploratory programs in neurology. In a recent study, we observed dose dependent editing of the UGP-two in the posterior compartment of the eye including the retina at multiple time points post injection.
We used intravitreal injections, a clinically relevant route of administration to deliver these AMAs to mouse eyes. At 1 week post dose, we observe up to 50% mean editing and these high levels of editing persist for at least 1 month post dose. We also observe wide distribution of AMOS at the 1 month time point in the sections from these eyes as shown by the pink staining on the right side of the slide. These data suggest our platform may support development of AMOS for ophthalmology diseases. Turning to CNS.
Last year, we demonstrated editing in multiple CNS cell types as shown on the left and in the CNS mice in the CNS of mice at single time point with the UGP-two targeting AMO. The initial result was exciting and we saw to replicate it and explore durability of editing in CNS. We performed a follow-up study where mice received that same single 100 microgram dose, but were followed over a much longer window of time. As in the previous experiment, we observed editing throughout the brain with peak editing observed approximately 1 month post dose in all the tissues and the robust editing persisting for at least 4 months post dose. We're very excited by the durability of this editing as this result is consistent with what we have demonstrated with GalNAc conjugated AMERSH and stereo pure PN modified constructs across other modalities.
We also evaluated tissues from 3 month time point and observed wide distribution of AMERS throughout the CNS as shown by the pink staining in the top two rows of the slide. As the target landscape for ADAR editing outside liver CNS and ophthalmology is vast, We also evaluated the potential of unconjugated AMRUs using systemic delivery. In preliminary studies in NHPs, we observed in several tissues of interest, including kidney, liver, lung and heart after a single subcutaneous dose. While desired editing levels will vary by targets, these results are compelling, particularly in hard to reach tissues such as heart. We're also evaluating the potential of unconjugated AMOS for delivery to the immune system are cells found in human peripheral blood.
Cells of the immune system are known to be difficult to edit, but editing in D cells holds great promise for the treatment of many diseases, including cancer and autoimmune diseases. After AMR treatment in vitro using free uptake, we observed robust editing in variety of immune cells in PBMCs, including CD4 positive and CD8 positive T cells, monocytes, B cells, NK cells and regulatory T cells. The work we are doing to expand the capacity of our ADAR editing modality is in its infancy. Many of the experiments I have shared so far today reflect our preliminary designs. Our work to improve our designs and to explore new applications for this technology is ongoing.
As we have demonstrated with our silencing compounds, as learnings from our platform inform our design principles, we can significantly improve the activity of these editing molecules. On this final slide, I show you a preview of what is coming. Much of the data I shared today were obtained with an AMR with an initial chemistry that edited UGP-two. The activity of this AMR in cultured neuron is illustrated in light green on the left hand left of the slide. On the right in dark blue, you can see that we are seeing 75% more editing in the same cells under the same conditions with our optimized chemistry.
We are currently applying optimized AIMAGE to therapeutic targets as we are about to hear from Ken and Philoma. Our ADAR editing modality has come a long ways in a short period of time. We have an elegant approach to RNA editing enabled by chemistry and biology expertise. We'll continue to establish our leadership position as we advance the therapeutic programs and scientific publications. I look forward to updating you again soon.
With that, I'll now turn the call over to Ken. Ken?
Thanks, Chandra, and good morning, everyone. Over the last several years, the evolution of our PRISM platform has shaped our neurology pipeline. Our 3 ongoing clinical programs, WVE-four for ALS and FTD, three for HD and N531 for DMD incorporate PN backbone modifications and leverage translational in vivo models providing greater insight into dose response relationships and target engagement. As these programs advance, we continue to apply lessons learned to characterize and bring forward new therapeutic candidates. Today, I'm excited to describe how we're applying ADAR within our neurology discovery pipeline to access targets previously thought to be undruggable.
Following on Chandra's update on the progress of our ADAR platform, we can now expand our neurology portfolio to include diseases where restoration of protein function is required and where we would like to access pharmacology that is currently beyond the reach of other oligonucleotide based approaches. RNA editing provides a unique approach to treat a wide array of neurological diseases that cannot be targeted through silencing or exon skipping mechanisms. As Chandra presented, we've demonstrated that we can achieve robust RNA editing in CNS tissues. Using UGP-two as an example and using 1st generation AMER molecules, we've demonstrated potent, widespread and sustained editing throughout the mouse CNS with the effect persisting out to at least 16 weeks following a single ICV dose. These data indicate that PN chemistry is driving widespread and durable effect when applied to AMIRs.
As described in Slide 57, there are several ways in which we could use ADAR to address disease mechanisms or disease causing mutations across a diverse spectrum of neurologic diseases from epilepsies to dementia, haploinsufficiencies to gain of function mutations. To provide one example of how we're using RNA editing in our neurology portfolio, I'll focus on correction of a specific nonsense mutation that leads to reduced expression of MECP2, a protein found in the nucleus of neurons and glial cells that is required for normal brain development. Mutations in MECP2 are the cause of Rett syndrome, a devastating neurological disorder mainly affecting girls and characterized by profound neurodevelopmental delays and seizures. MECP2 regulates expression of a variety of genes involved in neuronal development and synaptic plasticity. Nonsense mutations in MECP2 lead to truncation of MECP2 protein, a loss of the ability of MECP2 protein to localize to the cell nucleus and the loss of the ability of MECP2 to recruit other proteins required to carry out its normal function as a regulator of gene expression during brain development.
Using ADAR, we can edit nonsense mutations in MECP2 to restore expression and activity of MECP2 protein. Although individual patients can have distinct mutations in MECP2, our initial focus is on a common and prevalent mutation R168x, where X represents a signal to stop mRNA translation. Based on success in editing R168x, we can apply this approach to expand our RET program to develop AMIRs that address additional disease causing MECP2 nonsense mutations. In the example on Slide 59, we used ADAR to edit the R168x nonsense mutation. As you can see in this figure, using our AMER constructs, we obtained concentration dependent editing of MECP2 up to about 70%.
Incorporation of PN chemistry in the AMER molecules greatly improves editing activity. As shown in the bottom right figure, we see that ADAR editing restores full length MECP2 expressed here as a GFP fusion protein in this in vitro system. ADAR editing of the R168x mutation replaces the missense stop codon with an mRNA triplet encoding the amino acid tryptophan. As tryptophan is not normally present at that location in the wild type MECP2 protein, it became important for us to show that the edited MECP2 retains its normal cellular localization and is able to associate with other nuclear proteins that are required for MECP2 to carry out its role as a modulator of gene expression. As I mentioned earlier, MECP2 is a nuclear protein.
In Slide 60, we show that edited MECP2 is present in the nucleus of transfected cells. We see this using immunofluorescence staining of epitope tagged MECP2 shown in blue in the left hand figure. We also see this using subcellular fractionation shown in the figure on the right where we demonstrate that MECP2 is found in the nuclear fraction and not in the cytoplasmic fraction of transfected cells. To further demonstrate that edited MECP2 retains its normal function, we use the co immunoprecipitation strategy to show that edited MECP2 associates with members of a protein complex that work in concert with MECP2 to regulate the expression of target genes. As shown on the right side of Slide 61, immunoprecipitation of MECP2 from transfected cells also pulls down other members of the protein complex that are critical for MECP2 to regulate gene expression.
Together, these data strongly indicate that edited MECP2 is present in the nucleus and associates with binding partners that are important for its normal function. Ongoing studies are looking to demonstrate that edited MECP2 restores regulation of known target genes. Changing gears now to an often discussed use of ADAR editing, which is to modulate protein protein interactions. Protein protein interactions have been notoriously difficult to drug using small molecules, particularly when the interaction interface is shallow, large and hydrophobic or buried deep within a protein fold. In addition, small molecules targeting these interactions often have properties that give them poor specificity and poor selectivity for the desired target.
RNA editing to change amino acids within a protein interaction interface can overcome the limitations of small molecules and provides a novel approach to modulating this class of targets. To exemplify our ability to modulate protein protein interactions using ADAR, we turn to the well characterized HEAP-one Nrf2 system. The transcription factor Nrf2 is the master regulator of the cellular antioxidant response, is involved in the metabolism of xenobiotics and is involved in immune cell activation. An important role in the pharmacological activity of immunomodulatory drugs used to treat CNS indications such as multiple sclerosis. Under normal cellular conditions, Nrf2 is bound to the regulatory protein KEEP1.
Binding to KEEP1 retains Nrf2 in the cytoplasm and targets it for degradation by the proteasome. However, under conditions of oxidative stress, the interaction between Nrf2 and KEAP1 is disrupted, stabilizing Nrf2 and allowing it to translocate to the nucleus where it activates expression of a host of genes involved in the cellular antioxidant response. As a proof of concept experiment, we look to see if we could mimic the cellular stress response by using ADAR to edit individual amino acids at the protein protein interaction interface between Nrf2 and KEEP1. If these edits work as designed, we would expect to see downstream activation of the Nrf2 gene expression program even in the absence of cellular stressors. On Slide 65, we demonstrate successful mRNA editing of KEAP1 and Nrf2 at 8 unique sites within each protein.
Each site was edited using a unique AMR. As you can see on the right, editing ranged between 20% to 60% across these targeted sites. To confirm that the edits were biologically meaningful, we next looked at the expression of genes dependent on the stabilization and nuclear translocation of Nrf2. The right side of this slide shows the effects of individual AMR treatments. As expected, treatment with each AMR resulted in increased expression AMR resulted in increased expression of known downstream Nrf2 target genes involved in the antioxidant response.
Control treatment did not result in increased expression of any of the Nrf2 target genes indicating that AMR treatment did not lead to Nrf2 dependent gene expression changes through non specific mechanisms such as increased cellular stress. In summary, we continue to advance our neurology portfolio. In our silencing programs, we've previously shared potent and extremely durable target engagement and widespread drug distribution throughout rodent and non human primate brain. Although relatively new and in early stages of discovery and preclinical characterization, our use of ADAR editing in the CNS provides additional opportunities to address unmet needs in patients suffering from neurodegenerative disease, allowing access to targets and mechanisms that cannot be approached through modalities such as silencing or exon skipping or using small molecules. This is truly an exciting new frontier for WAVE and for neuroscience, opening an array of new opportunities in neurologic disease.
With that, I'll turn the call over to Paloma to discuss our alpha-one antitrypsin program.
Paloma? Thanks, Ken. Hi, everyone. I'm very excited to be speaking with you all today. As Chandra described, we demonstrated our AMRs are GalNA compatible and can achieve significant RNA editing in vivo and liver, including in the liver of NHP.
These results have led us to rapidly advance our first ADAR editing program for a hepatic indication, alpha-one antitrypsin deficiency or AATD. AATD is an inherited genetic disorder that is most commonly caused by a point mutation in the SERPINA1 gene, commonly known as the Z allele. This mutation leads to misfolding and aggregation of alpha-one antitrypsin protein or ZAAT in hepatocyte and the lack of functional AAT in circulation, which results in progressive lung damage, liver damage or both. With ADAR editing, we aim to correct the SERPINA1 mRNA to restore circulating functional wild type alpha-one antitrypsin protein or MAAT to protect the lungs and reduce ZAAT protein aggregation in liver, all while retaining the innate physiological regulation of MAAT. With our GalNec conjugated stereo pure AMRs, we anticipate replacing chronic weekly IV AAT augmentation therapy with a subcutaneous administered therapy that addresses all goals of treatment.
This is superior to a silencing modality, which would only impact the liver. Of note, approximately 200,000 people in the U. S. And EU are homozygous for the ZZ mutation with the highest risk of lung and liver disease. Earlier this year, we presented data demonstrating restoration of wild type MAT in vivo with ADAR editing with our initial AMR design.
Today, I will start by reviewing those data and will provide an update on the specificity of editing and durability of protein restoration from that study. Using PRISM based chemistry optimization, we continue to enhance the editing potency of our GalNec AMERS. I will share data demonstrating how this optimization translates to protein restoration in vivo. Finally, I'll speak to our path to selecting a development candidate. We started with the in vitro evaluation of multiple bottleneck gamers with unique chemistry.
Shown here on Slide 71 are SA1-1 and SA1-two. We successfully demonstrated upwards of 60% editing of the SERPINA1Z allele transcript to wild type in hepatocytes in vitro, which led to a threefold increase in functional wild type AAT protein. Supported by these results, we developed a proprietary transgenic mouse model containing both human SERPINA1 and human ADAR that enables pharmacokinetic and pharmacodynamic assessment of human specific GalNAc AMRs in vivo. This human ADAR mouse enables us to optimize AMERS to human ADAR, which is expected to improve translation into the clinic. Of note, aggregation of human AAT protein in liver, which is observed in Slide 71.
We next advanced 2 distinct AMRs, SA1-three and SA1-four into an initial in vivo study to assess editing and protein restoration after 1 week. Following 3 subcutaneous doses, we achieved up to 40% editing at day 7. We were encouraged by these initial results as they approached the level of correction representative of a heterozygous MZ patient with very low risk of disease. To evaluate the specificity of the SA1-four GalNAcamer, we performed RNA Seq. On the left, you can see total sequence coverage across the entire SERPINA1 transcript for the AMR treated samples.
The percentage of unedited T and edited series are indicated for each group. Editing is only detected at the intended on target sequence in the SERPINA1 transcript. Thus, the protein being produced using this approach is truly wild type MAAT protein. This also confirms there is no editing of bystander residues as has been seen with DNA targeting approaches. Furthermore, to assess off target editing for the whole transcriptome, we applied a mutation calling software to search edit sites.
From this analysis, we observed nominal off target editing across the transcriptome. Sites where potential off target editing occur at either low read coverage in the analysis or occurred at low percentage of less than 10%, indicating that these are rare events. In both analyses shown on the left and right, we find a high percentage of editing that is specific for the target site in the SERPIN A1 transcript. Next, we looked at how this level of editing impacted the circulating human AAT protein. We saw a 3 fold increase in circulating AAT as compared to PBS control at this initial time point.
This magnitude of increase is promising as it is representative of 1, the fold increase that may achieve phenotypes with lower risk of disease and 2, total circulating AAT concentrations approaching 570 micrograms per ml or 11 micromolar in these mice. This result established a floor from which to optimize potency, which I'll discuss later on. Using mass spectrometry, we investigated the isoforms of the circulating AAT protein and confirmed that the majority was restored wild type MAAT. It was very exciting to see such levels of wildtype protein being generated post editing at this first time point. As you can see on the right of Slide 75, we also observed that there was a significant increase in neutrophil LSPACE inhibition post editing, confirming the functionality of this restored wild type MAAT protein.
Our next step was to understand how durable this protein restoration was over time. We repeated this experiment with the SA1-four Galenic AMR out to a 35 day time point. As shown on the left hand side of Slide 76, following 3 initial doses, we observed a significant and durable increase of greater than or equal to 3 fold over PBS control out to 35 days. Notably, with our initial AMER chemistry, we maintain 11 micromolar threshold for approximately 3 weeks in the disease model. As shown on the right side of the slide, we confirm the presence of wild type MAAT protein at the day 35 Also, at this time point, we observed elevated zaAT protein levels in the AMERT treated group as compared to PBS.
This suggests clearance of intracellular DAT aggregates with AMER treatment. So next, we wanted to understand if chemistry optimization could further improve potency and durability. In vitro, we demonstrated that we could design more potent editing AMRs. With sequences held constant, we adjusted chemistry and stereo chemistry to optimize the potency of the SA1-four GalNIC AMR. With 2 optimized Galenic AMRs, SA1-five and SA1-six, we demonstrated ADAR editing of approximately 50% with half the dose used in our first study in mice at the same day 7 time point.
Next, we wanted to understand how optimization impacted protein restoration. We repeated the initial in vivo study with an optimized version of the SA1-four AMR named SA1-five and look the circulating AAT protein at an initial day 7 times point. Consistent with an increase in percent editing, as shown on the right of Slide 78, the total serum AAT relative to PBS was increased from 3 fold to 4 fold or greater than 15 micromolar with a SA1-five AIMR. When evaluated with mass spectrometry, the proportion of wild type MAAT was increased from 75% to approximately 85% of total AAP. Importantly, the optimization in chemistry establishes a range within which to advance dose range studies over longer duration.
In summary, our initial in vivo study has demonstrated that our AMIRs restore therapeutically meaningful levels of functional wild type MAAT protein at an initial time point. These AMRs are highly specific with no notable off target or bystander editing. This protein restoration is durable with significant levels of wild type MAT detected in serum at over 30 days post last dose. We continue to optimize our AMIRs and we have demonstrated that we can improve editing efficiency, drive AAT protein above 15 micromolar and also increase the overall percentage of circulating wild type protein to 85% of total. Our focus today is advancing ongoing and planned studies that will assess durability, dose response and PK PD of optimized AMERS.
We'll also be looking at the reduction in VAAT protein aggregates in liver and changes in liver pathology. We expect to have an AATD development candidate in 2022. Next, I'll turn back to Paul. Paul?
Thank you, Paloma, and thank you Chandra and Ken for speaking in detail about these exciting updates. With dosing underway in WVE-four and three clinical trials and in 531 soon behind, we are entering a potentially transformational period of data generation for WAVE. We believe clinical data will unlock value in multiple ways, including insights into the clinical effects of PN chemistry by way of biomarker results and implications for dosing intervals. Through 2022, we will also gain insight into the ability of PN chemistry to improve cellular uptake and distribution with our exon skipping modality. Our advances in chemistry sets us apart from others in the field and are enabling us to lead the way in developing ADAR editing therapeutics.
Starting with our Alpha-one antitrypsin program, we are on a path to generate proof of principle that we can harness human biological machinery to treat genetic diseases the liver and beyond. And with that, I'd like to turn the call back to the operator to begin the Q and A portion of our program.
Our first question comes from Salim Syed with Mizuho. Your line is open.
Great. Thanks so much for all the detailed color guys. Looks great. Just a few for me if I can. Paul, just a high level strategy question here.
Obviously, the presentation today focused a lot on ADAR. And when I look at your pipeline slide right now, it's just the Alpha-one antitrypsin program. So just curious how you're thinking about the longer term strategy here with your ADAR platform. How much of your pipeline do you think will be ADAR if we were to think about this in a 3 year timeframe or a 5 year timeframe? And the second question, maybe just I don't know, I guess anybody can take this one.
On Slide 20, this is a slide that you guys had presented prior regarding the silencing and the splicing of PSPO chemistry versus PSPN chemistry. And I'm curious, why the darker blue dots seem to have a little bit more variability than the teal dots, so the PNB in the darker blue here. Is there some natural variability or more variability on the PN chemistry side versus the PSPO? Thank you.
Great question. So we'll do we'll take the strategy question first and then we'll cover the PSPO. And I really appreciate really trying to think about the advancement of ADR. Obviously, we're rapidly pushing the AATD program forward and it's because it does 2 things. 1, obviously, it's an important and meaningful disease with a substantial number of patients who could be potentially amenable to the therapy.
So very important for what we're developing it for. Equally important is the human proof of principle data that comes from that in demonstrating our ability to measure on target engagement of editing measuring the alpha-one antitrypsin program. So this program really allows us to do both features, 1, in a meaningful medicine, but also 2, be able to validate ADAR in humans. Secondly is, as you point out, and that was really I'm glad you picked up on it today is really the breadth of where ADAR ADAR can potentially go. And I think there's really 2 areas of focus and I think you heard that today.
One is obviously based on the exploration of ATD continuing to explore Galmec conjugated medicines that have the potential to edit. And we do see the opportunity to expand the pipeline there. I think the other that's equally important is the work that Ken was speaking to about opening up an area of biology that we have extensive experience in, which is neurology. And so across the path around 4 therapeutic areas, we do see a substantial build out of, ADAR editing capability. I I think we'll continue to also view the opportunity to collaborate with others as we expand into other therapeutic areas as well.
But I think the key is really, as we said at the very beginning of the call, that it really opens up the ability to utilize multiple endogenous machineries and cells of silencing, splicing and now editing. So that as we think about important and meaningful diseases, we have this unique position now to be able to pick the right tool to do the right job. And so there is a vast universe of therapeutic potential that over the next 3 to 5 years, we can open up. So we're pretty excited about that. But I think what we've also learned from the past is a data driven approach.
And I think that's why also today it was really important for us is as we talked about new ways of utilizing ADAR like nonsense mutations or drugging and modulating protein protein interactions, it was important us to go beyond the statement and demonstrate that indeed we could build AIMERS that have that capability. So we're excited about what's to come and we're marching through with the portfolio to do that. Your second question that relates to the rank order, Ask Chandra if she wants to add to that, because they are rank ordered by sequence. But Chandra, do you want to add to that?
Yes, sure. So the graph is actually plotted in a way that we rank ordered using that PSPO compound as a reference. So everything is towards that. So we didn't rank order the PN. So that's why you see a uniform line for the PSPO.
Got it. Okay. Makes sense. All right. Thanks guys.
Thank you.
Thank you. Our next question comes from Mani Foroohar with SVB Leerink. Your line is open.
Hey guys, thanks for taking the question. I guess tightening a little bit more narrowly at Alport antitrypsin, you kind of being in the clinic perhaps next year, obviously, there's quite a bit of optimization that goes into before you go into humans. Can you give us
a sense of what are kind
of the key metrics or hurdles you're looking to clear before getting into 1st in human? And then I have a follow-up on regulatory pathway.
Sure. And it's a great question. I hope and I think what you pointed out was really our path to candidate selection in 2022 and that will really inform the clinical timeline. So to that point, I think Paloma did a really nice job of assessing where we are. I think we were able to achieve substantial chemical optimization on potency.
I think we're there. I think the next piece that we're evaluating is that PKPD dose response and looking at durability, so that we want to go into the clinic as quickly as possible. We also want to go there with a molecule that we think can really go the distance. So I think there's a piece around durability, dose response. And then one of the other features that's pretty interesting that Colombo pointed out as well is we do see the ability potentially to actually see a removal of the aggregates from the liver.
So being able to treat both hepatic by clearance of those aggregates as well as lung is something we'll evaluate as we build the total package together to the clinic. But I think the key is we need to establish that candidate and along the way ample opportunities for us to provide updates both on the data that we're generating and as well as how that informs the clinical timeline. But it's an exciting place to be starting at now that we see substantial editing.
Great. That makes sense to me. And then I guess also on AAT, we've seen a little bit of regulatory clarity from Arrowhead. Obviously, that's a very different oligotherapeutic technology. What do you draw from what a potential regulatory pathway would be towards the pivotal indication?
At what point do you think you need to have a study with a biopsy endpoint? And how quickly would you be able to move into that?
I think we have 2 ways to think about this. And it's really 1st and foremost a different approach to the silencing approaches to your point right now, which is heavily focused on aggregate removal from the liver and what's the impact of the liver, which is what's unique about editing is restoration of the functional protein and protection of the lung. So I do think we have opportunities as part of those studies to be able to assess both. I think what we'll be starting with in the proof of principle study is answering the first most important question, which is do we edit and do we create measurable functional protein that's in the serum. So that'll be a critical inflection as we think about benchmarks from some of the protein infusion therapies.
And instead of kind of having to go for weekly IV infusions, bring patients to the potential of actually restoring functional balance of wild type protein that's there when the patient needs it, not over expressed, but there when it needs to be. I think the unique opportunity as we were just saying around the potential is also see clearance of the aggregates, let's us really think about the opportunity on both ends of the spectrum, liver and lung. And then that obviously to your point will require potential evaluation of the liver. But I think we'll also be able to assess measurements in the serum of what's happening to the Z protein that could be leaving the liver. So we could have a biomarker assessment that's at least enabling us in the clinic to look at whether or not we're having an impact on both liver clearance of aggregates as well as restoration of protein function.
So that's part 1. And then obviously first step is getting into the clinic and then that's clearly the assessment that we do as part of that proof of proof of mechanism study. I think what's important on a third piece is not only liver and lung, but also what that opens up for the entire ADAR editing capability in general. So there's an ability to assess this particular therapeutic program, but by doing that really unlocking our capability to expand much more broadly across other editing modalities.
Great. That's really helpful. I think I have another a lot of the questions waiting so I
can hop in the queue. Great. Thanks, Sean.
Our next question comes from Joon Lee with Tuohyst. Your line is open.
Hi. In addition to optimizing your AMERS for editing efficiency, is there a way to screen for immunogenicity? Do certain stereo pure oligonucleotides have more or less immunogenicity compared to other stereo pure ones? And do AMERS form secondary structures? Just curious because a company developing antisense oligo for engiman has impressive efficacy, but has some inflammation issues that the FDA may be concerned about.
So any thoughts there would be helpful. And I have a follow-up. Yes.
No, and we have a lot of thoughts there, because I think when we think about programs like you brought up before, I mean, I think that brings up just the challenges that Chandra spoke to at the very beginning of the call, which is when you're dealing with mixtures of 1,000, even 1,000,000 of oligos depending on the length, you have all different isomers, right? So isomers are not a wave issue. Isomers are a mixture issue. What we have is the ability to do what you're saying, which is how do we create. And that's really the work that we've done now over the last years, which is being able to build characterization of individual isomers before we go into study.
So to your point, the work that goes into assessing a molecule that we're going to potentially bring to the clinic would involve that assessment around tolerability and immunogenicity. I think part of the characterization process that goes into identifying the individual oligo. The benefit of that and really getting back to the whole thesis when we started around really rationally designing and why you move forward with a single drug is, once we do characterize it, that will be the isomer that goes into a patient. So you can have fluctuations of what dominant isomers are and what aggregates. And I think that can cause some of those that changes you're alluding to.
So as part of the buildup to selecting the program, yes, we do that analysis, not just in how we pick the sequence, but actually on the design of that individual oligo before it goes into the clinic. In terms of structure, and I'll just see if I don't completely answer a little bit for Chandra. But I think one of the other pieces that's important for us using short therapeutically relevant size oligonucleotides is to avoid really long oligos that can form secondary structures. So by staying in the size range we are and the modifications we are, we're not concerned about that. That's obviously a bigger concern as people build potentially bigger and longer molecules.
Okay. And you were either in Q2, I had a second question.
Yes. How does the reach of 8R editing system compare to CAS13 and now CAS7-three eleven editing capabilities? If you can compare and contrast some
of the pros and cons there, it
would be great. Thank you.
Yes. And I'm happy also to kind of keep opening up as we look back. But I think stepping back again on why we approached RNA editing and RNA editing via ADAR is 1st and foremost to use an endogenous machinery inside the cell so that we could drug it, attack it, right? So to be able to utilize an endogenous based editor inside a cell to do the work we need to do. We like RNA for the period of pieces that we brought up at the beginning, which is when we can control re dosing, so we can give the drug more frequently.
It's reversible. We can characterize and make sure that by targeting RNA, we're not permanently editing the human genome, right? So we're not interfering with DNA. So there's a whole bunch of pieces that really drive our piece of building a reducible, titratable, reversible RNA editing capability that we see as a core feature as we think about editing differently than to your point some of the other tools that are available for editing.
Great. Thank you. Yes.
Our next question comes from Paul Matteis with Stifel. Your line is open.
Hey, thanks for taking our question. This is Alex on for Paul. On the AAT program, the 15 micromolar is great. I'm just curious if you're hoping to get more towards the normal serum concentration in the 20 plus range as you move forward? And would that need to be all wild type?
How are you thinking about sort of the target for achieving that serum level for your lead candidate? Thanks.
Yes. No, and we appreciate it. And when we think about the range, this is why that threefold number becomes really important is, what we are trying to do in an attempt for these patients who are homozygous. So if we think about the homozygous patient population about 200,000 patients in the U. S.
And Europe, the premise for the treatment for these patients is to restore a heterozygous phenotype. Therefore, by achieving even that these patients who go on to get protein replacement therapy at 11 micromolar weekly, Our view is the ability to give them a restorative protein where they can consistently stay above that threshold in a way that they can self administer subcutaneously and hopefully do that infrequently. So I think as we get to your point on 50 micromolar, we think we're above that range. Obviously, the steps that will go forward as we kind of move to the clinic is really assessing how durable that is, where they stay in that range, and what the redosing intervals are. But our view is on a potency threshold, we're there, we'll have to continue to evaluate that as we move toward the clinic.
But again, the ultimate goal of therapy for these patients is getting back to an MZ phenotype, MZ and that we believe we can achieve based on where we are now. So that's the current plan, but we want to be able to evaluate, again, how frequently they need to administer. I mean, we think as we talk to physicians and patients, the ability to have subcutaneous administration that doesn't require patients to go in frequently, whether it's 1 or even to emergence to 3, having to go into hospitals for IV infusion, that's important. I think the second piece just not to forget that right now we're talking about a threshold and protein, which again provides pulmonary protection. But I think what we're also interested in evaluating we think about the characterization for looking at the liver clearance of the aggregate opens up the second piece where we see the advantages of an editing approach now, which is both the protein production that you're referring to, but also the removal of the liver aggregates, right, which ultimately can provide hepatic protection.
So if you go back, I mean, we're already achieving with that dose that Paloma was sharing 50% editing, which is kind of where you theoretically want to be for a heterozygous phenotype. So I think that was really the important update for us today was moving even from where we were to where we are and now really setting us on the course to bring in program forward. So we're excited.
Thanks. And then one follow-up question to beyond sort of standard safety studies, what sort of work can you do, if any, in non human primates to kind of get a better understanding of those properties before getting into the clinic in humans? Thanks.
No, great question. So what's unique is there aren't transgenic NHTs. So for us, it really is about really evaluating the PKPD from the SERPINA1 level. And then ultimately, like we would do for any program, evaluate distribution, safety and all of the other work that you do in HP. The support we have and I think this is why we're excited about this program really becoming a defining program for ADAR and editing for us is there is very good correlation between PKPD from a mouse with Galmec to an NHP with Galmec to a human.
And so leveraging on the
Galmec distribution work, we can lean on that in terms
of looking at correlations of C9, as we think about SNP3, as we think about N531, it's C9, as we think about SNP3, as we think about N531 is being able to have PKPD modeling to support dosing and then animal models to support therapeutic index and ultimately have that translate to an efficient starting dose in the clinic. And I think we're on the path to evaluating that with the alpha-one antitrypsin program.
Great. Thanks so much.
I don't
know, Ken, if there's anything you want to add, but
No, I would just follow-up. It becomes just like any other development program, right, where we want to learn about dose response relationships and tolerability in a highly relevant pharmacological species as we prepare to go into the clinic.
Thank you.
Our next question comes from Luca Izzi with RBC. Your line is open.
Great. Thanks so much for taking my question and congrats on all the progress. Great to see the editing efficiency going up to higher doses. Maybe one question on business development and the other one on the clinical path here. So on business development, I think we'd love to hear your thoughts on how you're thinking about BD in the context of ADAR.
It looks to me that the ProQR and Eli Lilly deal as well the Shape deal with Roche were really designed to share the long term upside more than optimizing for the upfront cash. Wondering if a similar deal will be of interest to you. And then maybe on clinical, just double clicking on a prior conversation. I know early days, but how are you thinking about the ultimate endpoint that is required for approval for A1AT? Will A1AT serum level be sufficient?
Or do you need to show either an SPV1 benefit, maybe a fibrosis benefit or possibly both? Any thoughts on that would be great. Thanks so
Yes. No, I'm excited to talk about both of those topics. I'll just say at the beginning, one of the things that was exciting as it relates to the 50% editing we shared is we actually saw the 50% editing at half the dose. So I think the improvement of potency is not just about being able to push doses higher to see more editing, which is obviously exciting in and of itself. But I think what was critical, at least from the take home is that 50% number was achieved at half the dose from those initial data sets we shared previously.
So this is an important note. As it relates to BD, I think you summed it up really nicely for us, which is there's a tremendous amount of value that we can create with the current program on its pathway. And I think we want to make sure that as it relates at least now in alpha-one antitrypsin that we can make sure that that program, as I said, goes the distance to get to clinical evaluation and assessment of protein and really validate the underlying principle of editing. Now as it relates to being able to expand the universe of things we can do, and as we said, there's a substantial number of different indications as we share today from everything from immunology and what we can do in immune cells through CNS. I think we're very disciplined around spending the resources and the capital that we have in areas that are aligned with our core strategy.
And I think as we think about the ability in CNS and other tissues to drive it there. So I think there are opportunities as we just have discussions with a number of ways of expanding our portfolio. BD is a core driver. But it's important in another piece that we've used in the past is that we also want deals that not just fully fund the work that we're going to do, but really bring additional capital into Wave that are runway extending. So deals that are runway extending, deals that expand the portfolio are critical to us.
So as we look around, it's great to see interest shaping up in this space. But BD has always been part of our strategy and will continue to be. As it relates to clinical endpoints, as we shared earlier as well, the initial clinical endpoints will be really focused on are really that assessment of protein because it's going to tell us a lot, right. The ability, 1, to see and characterize wild type protein is going to give us the ability to characterize our editing And so as we think about that core initial data set that's going to provide critical information to us, that's really important. And then once we have that, there's advances on two fronts.
1 is obviously how the program progresses around threshold levels of protein and what happens to the liver in terms of demonstrating protection of both and how we think about studies that can build the label appropriately. But then there's also the critical feature, which is again unlocking the full potential of ADAR where we will be driving ADAR programs across the portfolio that gets supported by that. So a lot of activity in this space and that's why we're excited to share that today with you.
Got it. Thanks a lot.
Thank you. Our next question comes from Eun Yang with Jefferies. Your line is open.
Thank you. So for the optimized AAT formulation, you mentioned the clinical candidate selection next year. Once you selected a candidate, I assume that you're going to be running an IND enabling study, which could take about a year. So is it reasonable to assume that clinical studies start sometime in 2023?
So before we guide to when the study is going I think you're right. So the good news is they don't take lots of years. And we view it as a lot of work goes into that candidate initially that defines its pharmacology. And then the next thing happens, as you pointed out, are what are the IND enabling studies that need to be done. Now the benefit again of being a RNA therapeutic that in a lot of ways is similar to what we've done before is with 3 clinical programs already underway and having a pretty precedent path and characterization, we would take this through the standard IND enabling studies.
I don't know, Ken, if there's anything you think we should add to that?
No, I think that's right, Paul. It's going to be a fairly standard and straightforward IND enabling study package. Really only wrinkle is the duration of action and how long those studies need to run. But we'll have more information about that as a lead emerge or candidate emerges when we get ready for those studies.
Okay. And then one of the gating factors before choosing the clinical candidate is obviously durability. So can you talk about what's the kind of like a durability you are looking for, number 1? And the second question is on the Q2 conference call, you guided that there would be additional durability and dose response data in second half of this year. So does that apply to the optimized AAT formulation?
So I'll answer both those questions. So we provided the durability on the first construct and I think that's what we were sharing in terms of where we were in durability. That got us as Paloma showed out for 3 weeks. I think our view is given that right now on the protein, it's a weekly IV infusion and those is more work. We want to go as long as possible.
I mean, the advantage of this therapy is 1, the potential for self administered sub q therapies. So the key for us is to push that dosing interval out as long as possible. Step 1 in that was, could we achieve higher potency? So push that curve up and as you saw in the data today, we could achieve that. And the next is to see how that characterizes itself out in terms of durability.
But I think we've learned across the PM platform that that is a core characteristic of our medicines. We go back to the C9 preclinical data. We had data, I remember, out at 6 months still with complete knockdown of the poly GP. So I think to Ken's point earlier on the work that gets done, we're going to be characterizing that durability work. But the first core threshold that we needed to achieve was substantial potent editing that puts us well within the range that we would like to be in.
And with achieving that, I think now is about the optimization of the rest of the pharmacology.
I see. So are we expecting additional data before year end or is it going to be more in 2022?
So I think there's always a potential with a lot of work underway to deliver data. I think guiding on that is always difficult, but the clinic and it is appropriate, we'll continue to provide updates on key drivers that kind of build to the program. So I assume we'll have ample opportunities to continue to provide updates on the program. You did mention one thing at the beginning and I think it's important because we do know that others are using like liposomal formulations. And so obviously you put a formulation into a vial, but important to remember is that these are Galanec conjugated oligos.
So we're not formulating them in timothosomes or LNP.
I see. Thank you very much.
Thank
you. Thank you. This concludes the Q and A portion of today's webcast. I will now turn the call back to Paul Polno, President and CEO of Wave Life Sciences for closing remarks.
Thank you everyone for joining the webcast and thank you everyone at Wave for their hard work and especially in preparing the data and presentation today. We look forward to connecting with many of you after this call. Have a great day. Thank you.