Nielsen and we expect to share data in the first quarter of next year. There is an immense need for effective therapies for AATD, which is caused by the aggregation of mutant Z-AAT protein in the liver and lack of functional AAT in the lungs. Damage in the lungs occurs during exacerbations that induce an inflammatory acute phase response. Healthy individuals are able to produce elevated levels of protective functional AAT protein during these events, and it protects the lung from damage. Progressive liver disease results from Z-AAT-induced proteotoxic stress. Treatment today is limited to weekly IV augmentation therapy for lung disease, which does not allow for protective increases in AAT protein during acute phase response without additional infusions. There are no approved therapies that address AATD liver disease, and the siRNA treatments in development could potentially exacerbate lung injury.
There are an estimated 200,000 homozygous PiZZ individuals in the U.S. and Europe. We've heard many powerful testimonials directly from the AATD community that speak to the harsh impact of this disease, which progresses over time as a result of accumulated injury and is often misdiagnosed. Risk for AATD is related to genotype, with MM being healthy and MZ individuals having low risk for disease. ZZ individuals have high risk for both severe lung and liver diseases due to the lack of wild type M-AAT protein in serum and misfolded Z-AAT protein trapped in the liver. Since the approval of weekly IV augmentation therapies to treat lung disease, the field has focused on keeping serum AAT levels above a minimum threshold, in part because ZZ individuals do not produce any M-AAT and have a limited ability to increase serum AAT levels during an acute phase response or exacerbation.
Editing by RNA at least 50% would shift ZZ individuals to an AAT biomarker profile consistent with the MZ phenotype with low risk of disease. One of the key treatment goals is to protect against lung injury by reducing the frequency and severity of exacerbations which drive disease progression. During these events, immune activity, proteolytic enzymes, and inflammation cause damage to the lungs because AAT protein, a key protector against these insults, is missing. On the left of slide eight, you can see the kinetic profile for C-reactive protein, or CRP, and AAT protein during an acute phase response. CRP spikes early, and the peak level impacts the intensity of the immune response. AAT protein expression is upregulated proportional to the CRP elevation. This ability to upregulate AAT is severely impaired in ZZ individuals with AATD, which is shown on the right of this slide.
The best way to limit exacerbations and the associated damage that drives disease progression would be to enable ZZ individuals to respond like an MZ or healthy individual and make protective AAT protein when it's needed. This is exactly what we were able to observe with WVE-006 during an acute phase response. Designed using our proprietary chemistry, which drives potency, stability, distribution, and delivery, WVE-006 has the potential to be the first treatment for AATD that enables patients to produce protective AAT protein when needed and address the root cause of the disease with a convenient and infrequent subcutaneously dosed therapeutic.
WVE-006 corrects the Z mutation, increasing circulating levels of wild type M-AAT protein and reducing mutant Z-AAT protein aggregation in the liver, thereby treating patients with lung manifestations, liver manifestations, or both. As Chris will share momentarily, our clinical data with WVE-006 strongly supports a differentiated therapeutic profile as we observed restoration of dynamic physiological AAT protein production during a non-drug-related acute phase response, efficient production of M-AAT, and corresponding decreases in mutant Z-AAT. Now, to review the clinical results, I'd like to turn the call over to our Chief Medical Officer, Dr. Chris Wright.
Thanks, Paul, and good morning to everybody on the call. Today, I'm excited to share an update from multiple cohorts of our Restoration 2 clinical trial. Our restoration program started with healthy volunteers in Restoration 1. This was a safety, tolerability, and PK dose escalation study that proceeded through single ascending and multiple ascending dose phases, ultimately evaluating up to three 600 mg doses of WVE-006 administered every other week. Data from Restoration 1 informed the starting dose of Restoration 2, our open-label dose escalation study, of individuals with AATD who have the homozygous PiZZ genotype. Each cohort was designed to enroll eight participants who began with a single dose of WVE-006 and then continued into the multi-dose cohort. Participants in the first lowest dose cohort of Restoration 2 received a single 200 mg dose of WVE-006 and were followed for at least 12 weeks.
These same participants then rolled over into the multi-dose portion, where they received seven 200 mg doses every other week for 12 weeks. They were then followed for 12 weeks after their final seventh dose. Today's update includes data from both the single and multi-dose portions of the 200 mg low-dose cohort, as well as data from the 400 mg single-dose cohort. I'll quickly touch on the safety and tolerability we observed in Restoration 1, the healthy volunteer study. The study enrolled 29 individuals on active drug, with participants receiving up to three 600 mg doses every other week in the highest dose cohort. WVE-006 was safe and well tolerated, with the related TAE being mild in intensity. In Restoration 2, we enrolled eight patients with AATD into each of the 200 mg and 400 mg cohorts.
Baseline characteristics were similar between the cohorts, with some minor differences in gender and weight. Participants mostly had no or mild evidence of liver or lung disease, as required by protocol, with one participant having moderate liver disease. All participants were required to be between 18 and 70, have a PiZZ genotype, and be non-smokers for at least one year prior to screening. WVE-006 was safe and well tolerated across all doses and regimens tested. All drug-related adverse events were mild to moderate in intensity. There were no serious adverse events or study discontinuations. Additionally, there were no clinically meaningful treatment-related lab, ECG, or vital sign changes. Overall, we're encouraged to see such a favorable safety profile for all evaluated doses. Now turning to our biomarker results in today's update. In the single and multiple dose cohorts, we observed a mean max total AAT of 12.9 μM and 11.9 μM, respectively.
These results were consistent across participants, as shown in the chart on the left, except for one individual with an acute phase response, which I will cover in more detail later. On the right side, we show the time course of RNA editing across the study periods. The bar graph shows the proportion of mutant Z-AAT in light blue and wild-type M-AAT in dark blue. Remember, individuals with the ZZ phenotype cannot make any M-AAT, so at baseline, circulating AAT protein is 100% Z-AAT. Even with a 200 mg single dose of WVE-006, M-AAT protein reached nearly 50% of total AAT, and editing effects persisted out to three months, marking the end of the follow-up period.
Looking at the multi-dose phase, where participants received seven total doses, one every other week, M-AAT protein reached a higher proportion of total AAT than in the single dose phase, with a mean max at around 64%. This proportion of M-AAT is consistent over most of the observation period, with the level still at approximately 50% edited protein two months after the last dose. These data indicate that the proportion of circulating M-AAT increases with multiple doses and that WVE-006's RNA editing activity is durable. Looking at the dynamic changes in M-AAT and Z-AAT at an individual level, you can see just how consistent the effects of WVE-006 were across participants, with everybody responding to treatment. On the top left, you see a substantial increase in M-AAT protein, which persists up to three months following a single dose.
There's a corresponding decrease in Z-AAT on the bottom left of the slide, consistent with the presence of significant RNA editing. A similar pattern with more substantial responses was observed in the MAD portion of the study, as shown in the middle of the slide in dark blue. Across both M-AAT and Z-AAT, there was a statistically greater effect in the MAD as compared to the SAD, shown on the right, supporting exposure-related enhancements of the effects. In the MAD, the mean max M-AAT reached 7.2 μM from zero at baseline, and there was a 60.3% reduction in mutant Z-AAT protein from 10.7 μM at baseline. If you look at the SAD data on the left again, you'll note one participant, also seen in the box plot on the upper right, had a very strong M-AAT response, followed by a decline over about four weeks.
In the next slide, I will focus on this response as it potentially is telling us something very unique and impactful about the effects of WVE-006. Looking closer at this individual response, serum total AAT increased to a level exceeding 20 μM. There was also a moderate elevation in C-reactive protein, or CRP, which is indicative of an acute phase response. After investigating this case further, it was noted that this 200 mg single dose participant experienced a kidney stone, which was unrelated to study drug. This presented us with a rare opportunity to assess the impact of WVE-006 on the dynamics of endogenous AAT protein production in the context of an acute phase response. As you can see, there's a simultaneous and rapid increase in both total and M-AAT levels, followed by a period in which AAT remains elevated. This pattern resembles a typical acute phase response.
To the right in the slide is the natural history data that you may recall from Paul's introduction, showing ZZ individuals are not expected to have increased serum AAT levels during an acute phase response. MZ and individuals both upregulate AAT when CRP levels are around 20 mg- 50 mg per liter. The observed strong AAT elevation in our ZZ participant affirms that WVE-006 enabled an MZ response. This participant illustrates that a single 200 mg dose of WVE-006 resulted in substantial upregulation of AAT when it was needed in a ZZ individual. Importantly, CRP elevations in this participant were moderate, so it's likely that WVE-006 could result in an even greater AAT elevation with a stronger acute phase response.
A longstanding goal of the AATD community has been to ensure individuals living with AATD are protected with sufficient serum AAT during exacerbations, restoring endogenous expression dynamics of AAT during an exacerbation when it's most needed to achieve this goal. These data represent the first ever therapeutic demonstrating restoration of dynamic physiologic AAT production during an acute phase response. Now turning to the 400 mg cohort, the single dose achieved serum total AAT of 12.8 μM and M-AAT of 5.3 μM. Circulating serum M-AAT levels reached 47.2% of total AAT, and Z-AAT decreased by 49% versus baseline. Relative to the 200 mg single dose cohort, greater M-AAT was produced and a larger decrease in Z-AAT was observed.
Based on the differences between dose levels in the SAD cohorts and the impact of multiple doses in the 200 mg cohort, we expect that the 400 mg multiple cohort may lead to even greater effects on AAT expression. The data gathered to date, along with the PK/PD modeling, supports monthly or less frequent dosing, and our 400 mg MAD cohort is currently ongoing with once monthly dosing. We look forward to sharing the complete 400 mg dataset with you in Q1 2026. I'll now turn the call back to Paul.
Thanks, Chris. Our goal in Restoration 2 was to recapitulate the MZ phenotype, including durable production of M-AAT, reduction of Z-AAT, and restoring the ability to produce a dynamic AAT response when needed. The results of our first cohort clearly show we have already achieved this goal. With efficient and durable RNA editing, we are restoring a biomarker profile in individuals living with AATD that is consistent with low risk of lung and liver disease, including total AAT protein levels of 13 μM and over 60% circulating M-AAT in the serum with no bystander edited protein. Consistent with what we would expect to see in MZ individuals, we are also restoring physiologic AAT production and the ability for ZZ patients to respond with increased protein levels during an acute phase response to prevent lung damage. By reducing Z-AAT levels, we have also had the potential to prevent liver damage.
Importantly, we have not observed any liver enzyme adverse events, nor do we use LNP delivery, which have known risks for hepatotoxicity. With convenient subcutaneous monthly or less frequent dosing, we have the potential to bring a truly transformative therapy to the AAT alpha-1 community, and we are incredibly encouraged by the safety profile we are observing today. GSK was early to recognize the potential of RNA editing and our multimodal platform more broadly. Their leadership in respiratory medicine development and commercialization makes them an ideal partner for WVE-006. We also continue to advance our GSK research collaboration programs. GSK has now selected a third program to advance the development candidate following achievement of target validation, which carries an associated milestone. Additionally, this collaboration enables expansion of our wholly owned pipeline of genetically validated targets, including inhibinE for the treatment of obesity.
Across WVE-WVE-006 and these collaboration programs, we are eligible for substantial milestone payments of up to $3.3 billion and anticipated payments in 2025 and beyond, which are not included in our cash runway. Our data with WVE-WVE-006 continue to demonstrate the clinical translation of our RNA editing capability, including safety, greater than 60% edited protein, and consistency across patients and impressive durability. Beyond WVE-006, we are building a wholly owned editing pipeline, which leverages these learnings. Our next expected clinical program is PNPLA3, a GalNAc-conjugated RNA editing program with the potential to address 9 million homozygous I148M carriers in the U.S. and Europe with liver disease. We have shown that RNA editing has the potential to be a superior approach to siRNA knockdown in liver disease patients with this genetic background due to the important role of wild-type protein.
We remain on track for CTA filing in 2026 for this program. Beyond WVE-006 and WVE-007, our siRNA program for obesity, we are continuing to advance a wholly owned discovery pipeline addressing hepatic as well as extrahepatic targets, and these programs utilize our proprietary chemistry to achieve best-in-class RNA editing and siRNA silencing in both rare and common diseases. Last year, we shared preclinical data highlighting our ability to direct silencing and editing to high-priority extrahepatic tissues, including CNS, skeletal muscle, adipose, heart, pancreas, and lung. We look forward to providing a further update from our emerging pipeline at our analyst and investor research day this fall. For over a decade, we've been relentlessly committed to unlocking the broad potential of RNA medicines to transform human health.
Today's results accelerate the already strong momentum of our best-in-class pipeline and the strength and differentiation of our platform, which continues to translate in the clinic. Building on today's results, we expect to share data in the first quarter of 2026 from our ongoing 400 mg multi-dose cohort, which is evaluating a monthly dosing regimen. In addition to our strong progress in AATD, our enlightened clinical trial in obesity is off to an excellent start. We've expanded and completed dosing in our second cohort, which evaluates a 240 mg dose, following favorable safety and tolerability, as well as robust active and E reduction observed in cohort one. We remain on track to report data from the expanded cohort two and data from cohort one in the fourth quarter of 2025, as well as data from cohort three during the first quarter of 2026.
Before turning the call over to questions, I would like to take a moment to thank all individuals participating in our Restoration clinical program, the clinicians involved, and the study staff. The patients we serve inspire the work we do every day, and from everyone at Wave, we'd like to express our sincerest gratitude. With that, I'll turn the call over to the operator for Q&A. Operator.
Thank you. At this time, if you would like to ask a question, please click on the raised hand button, which can be found at the bottom of your Zoom screen. You may remove yourself from the queue at any time by lowering your hand. When it is your turn, you'll hear your name called. Once you've been called upon, please unmute yourself and begin to ask your question. We ask that all participants limit themselves to one question. If you have additional questions, you may re-queue, and those questions will be addressed time permitting. We'll wait one moment to allow the queue to form. We'll take our first question from Joseph Schwartz with Leerink Partners. Please go ahead and ask your question.
Great, thanks so much, and congratulations on these groundbreaking results. I was just wondering, does it seem like there's an asymptotic set point above which it's hard to drive M-AAT, AAT protein levels when it's not needed? Why do you think that is? How do your models predict repeat dose 400 mg will work? Will it push the envelope further or push on a string?
I think it's a great question, Joe, and I appreciate the fact that we're actually going to be able to observe this over time in addition to the dynamic response rate. If we think about total AAT, it's a composition of Z, which obviously with editing would be expected to climb, which is what we saw, and M protein, which these patients don't have, increases. We do see that over time, so with longer exposure, the proportion of M-AAT in serum does increase. In fact, at higher doses, that M-AAT increases. Yes, we do think there's still a drive and more continued work that will push the M-AAT protein higher, both with time as well as increased exposure. What that is separate from, and I think this is really the unique aspect that we demonstrated today, is the dynamic response rate. This speaks to having more substrate to edit.
What we learned today, based on being able to observe what happens during an acute phase response, is during that response, you have an increase in transcription. There's more transcript to be edited. It tells us that we've got ample drug inside the cell with a catalytic enzyme with which to be able to edit. It's not substrate bound. If there's more substrate to be edited, as in the case of the acute phase response, we can continue to drive that editing higher to meet the challenges, as we saw getting up to 20 μMs where it's required. I'll ask Chris or Erik if there's anything else to share.
No, I think, Paul, you summarized it very nicely. I think the only additional thing to say is that I think we, as a field, need to kind of move away from this threshold at baseline. I think we're up over that threshold here already with the lowest dose. The most important part is to have a physiologically dynamic response to insult when it's needed. It's basically when AAT is needed as an acute phase protein, it can respond and go up into very high levels.
I think just to piggyback on Erik's last point, because I think it's an important one as we go through Q&A, is this notion of what's the therapeutic treatment for AATD? I do think the field comes at it with this concept of IV protein replacement therapy, to Erik's point on baseline, and this notion that if you infuse and sustain this kind of basal level, then it's there when you need it and needs to be at this threshold to mount the response. I think the data that we demonstrated today, which demonstrates actually that you can rise to meet the occasion wherever it is to drive down and protect during exacerbations, is the key therapeutic treatment for alpha-1 antitrypsin patients. I mean, that is the functional care. That's how you want to actually drive a response, is being there during these acute exacerbations to meet that need.
Taking ZZ patients who are non-responsive to these acute phase responses and now turning them to MZ heterozygous phenotypes to mount that response is huge in terms of the treatment goals.
Very helpful. Thank you for the insight.
Our next question comes from Joon Lee with Truist. Please unmute your audio and ask your question.
Hey, guys. Congrats on the data and thanks for taking our questions. Given competitive dynamics, including those from base editing, prime editing, and team writing, and some questions around the levels of M-AAT, do you have any plans to assess clinical outcomes to potentially differentiate from a commercial standpoint? Also, as a quick clarification, in your cohort two, how many have we had both liver and lung manifestations or one or the other? I just wanted to understand the baseline characteristics in terms of liver versus lung patients.
Yeah. On the last one, I think it's an interesting question to your point on how ultimately what do clinical outcome studies look like? I think there's no better partner for a respiratory outcome study than GSK with extensive experience in diseases of acute exacerbation in respiratory diseases. I think that is why they're excited about these data. I think this does demonstrate that ability to mount the response during acute exacerbations, which actually bode well for treating those clinical outcome studies.
If we think about the challenges in the field to date on IV protein replacement therapy and meeting those challenges have been, if you have these kind of trough levels that everybody's thinking about with a protein that's immediately consumed once you have these acute phase responses, then if somebody were at the trough at a point in time where they actually had an exacerbation that would be substantial, like in pneumonia, you could see that theoretically you'd consume all of the available protein that would be there to continue to protect the lung. When you have this opportunity, you're not rate limited. The body's making more, they're generating more protein, and you continue to meet those responses, which actually bode very well for continuing to follow those clinical outcome measurements.
I think there's a great partner thinking about that development pathway and commercial differentiation down the road that understands the space very, very well in conjunction with us. To your first question, I'll defer to Chris who can comment on the patient disposition.
Sure. Overall, our patient population had healthy or mild to moderate lung disease, as well as liver disease. You can look at the baseline table and you'll see that the majority of patients were F0, so didn't have any fibrosis. There were a couple that had F1 and one that had F2 levels. We allowed people into the study that had some degree of liver and lung disease since we don't really see any safety issues with this particular approach. They all performed well from the safety perspective.
I think the other piece, getting back to your question around just in general the commercial differentiation, besides just meeting the threshold levels and saying it's dynamic and it's there, I think as we think about an opportunity where you've got an infrequent subcutaneously administered GalNAc molecule, you can be thinking about quarterly, potentially even less frequently based on these dose exploration studies. I think highly differentiate the program and actually make it very amenable to patients to be able to use that and physicians to be able to monitor patients.
Oh, just a quick follow-up. Are there plans for cohort three? What does cohort three look like in terms of the dose and frequency? Thank you.
Obviously, as part of the collaboration, we have a partner who assumes the development on the other side. We are working closely with them in terms of the design of that third cohort. I think it's safe to assume, as Chris mentioned, we've got safety well to cover 600 and repeat dose. I think it would enable us to continue to build out the PK/PD curve, which could continue to support not just more AAT protein, M-AAT protein, but most importantly, derive this frequency strategy where we better understand the pharmacokinetics in terms of how infrequently do we need to administer this to mount a substantial response.
Thank you.
The next question comes from Salim Syed from Mizuho. Please unmute your audio and ask your question.
Hey guys, congrats on the data. Just one for me on cohort three. Paul, Chris, do you guys feel, Erik, do you guys feel like you have what you need here in terms of total AAT and M-AAT, just especially now given what we understand with the acute patient data? Are you more focused on durability or still pushing the actual levels here of AAT, M-AAT? Just related to that, with what we understand now with this acute patient data, it seems like we're still trying to understand the biology. Is there any room in the protocol here to add an additional cohort if you feel like you need to for the multi? Thank you.
Yeah, I think great question, Salim. Stepping back, thinking about the treatment goal, at the outset, the treatment goal on MZ was could you cross the 11 μM threshold of total with greater than 50% M protein. We had 12 μM with over 60% edited M protein, and that's still dynamically going up as we see time and the potential to increase dose. If we think about that, and I think the and is very important, the dynamic response, which is actually the biology of the disease, it's not an interesting finding between it. It's actually one of the important drivers in the disease. In fact, part of the differential diagnosis for the disease, if you see an individual, a patient who comes with a spike in CRP but doesn't have a corresponding elevation in alpha-1 antitrypsin deficiency, then part of that differential diagnosis is alpha-1 antitrypsin deficiency.
These are tightly linked in the literature and as part of clinical practice. As the KOLs we talk to have been talking about this being an opportunity for a long time for editing, I think they've been extraordinarily excited to see these data. As we think about those subsequent cohorts, they do give us the opportunity to do two things. One, continue to explore that dynamic range of total and M-AAT protein and what happens on those dynamics. Most importantly, as you point out, allow us to continue to explore the pharmacokinetic profile. I don't think given what we're modeling out quarterly or less frequently as we get to that third cohort, anticipate a need for any additional cohorts beyond that, because I think we'll have flushed out the dose range finding in terms of optimizing that dosing frequency across those three cohorts.
Got it. Thanks, Paul. Congrats again.
Thank you.
Our next question comes from Samantha Semenkow with Citi. Please unmute your audio and ask your question.
Hi, this is Benjamin Paluch on for Sam Semenkow. Thanks so much for taking the question. Recognizing that it's only an N of 1 with the patient that had the acute phase response, do you think the levels achieved with that patient could be sufficient to support approval?
It's a wonderful question. It's hard to contemplate approval. Obviously, above 11 μM, and that's consistent there. I think it demonstrates that one can get there. I think the key is continuing to explore the total profile. To your point, while it's one patient, that's the one patient that actually represents the dynamics of the disease. Being able to see what happens when you have an acute phase response, how ultimately do patients achieve, and being able to not just achieve an increase, but a substantial increase, 20 μM is the lower limit of what you see in a patient, is consequential. That ability to continue to explore that, and obviously with our collaborators in GSK who are thinking about not just the regulatory framework, but importantly, ways of elucidating. We keep talking about pushing the dose higher to explore total.
There's also this effect of what's that dynamic response and how much this, we saw that shortly after, so a patient leaves the office, they're more or less protected from those acute exacerbations. That's what you want. Given that that was at the lowest single dose, and again, just at the beginning of the study, and able to mount a response of 20 μM, I think really speaks well to editing and that editing is highly efficient, the drug's highly stable. It lets us think about the totality of the program and really exploring what do you need to have that response. I think 20 μM may just be the floor. This was a modest response in a kidney stone on CRP. If this were a pneumonia infection, you'd expect those CRP levels to be higher, and therefore with increase in transcription, actually drive higher levels of AAT protein.
It's interesting to continue to explore.
Our next question comes from Roger Song with Jefferies. Please unmute your line and ask your question.
Great, congrats for the data as well, and thank you for taking the question. Just a little bit more on the dose response from 200 mg to 400 mg. Very helpful to have this spider plot for the 200 mg SAD and the MAD patient. As far as I can tell, the 200 mg SAD mean peak is driven by two patients. Just curious how consistent for the 400 mg SAD, because you didn't give us the plot. I want to understand a little bit about the dose response from 200 mg to 400 mg on the SAD population and the MAD. Thank you.
I think from the 400 mg SAD perspective, we did see quite consistent responses, even broken down in terms of the individual responses at this time. I think what you can appreciate is if you remove the one outlier, which we're talking about, that had the acute phase response, the SAD max comes down slightly. You see more of a dose response, which is probably representative of the 200 mg versus the 400 mg. The 400 mg is already higher from the M protein production perspective. If you adjust the SAD from 200 mg, as I mentioned, you see that that's a bigger gap. We didn't want to sort of pull data points out and things like that. If you sort of look at the data and understand that outlier and sort of look at the mean without it included, you do see a bigger step up with the M-AAT with 400 mg.
We anticipate when you take 400 mg and go into a multiple dose study, you're going to see an equivalent sort of step up, just like we saw with the 200 mg MAD relative to the 200 mg SAD.
It is interesting, as Chris pointed out, if you take the M-AAT, and that's the best way to model the protein response with both repeat doses and exposure, you do see that continued increase in the 200 mg SAD to the 200 mg MAD. Ultimately, if you rebaseline that to 400 mg, I think the ultimate goal of what we're seeing is that that composition within the total protein of M continues to go up. That is really important. The dynamic response is ultimately what's going to be there to rise to meet the needs of patients when ultimately they have these acute exacerbations. I think we have both the threshold, as Chris is saying already, and you know, can expect to see more from 200 mg to 400 mg. Particularly important is that acute phase response and being there to meet that need starts early.
I have to say, that's why it was important for us to show not just mean plots, but actually all the patient responses. As Chris said, the responses were incredibly consistent. Everybody's seeing editing. It does speak to the fact that our GalNAc stable AMERs are delivering to those cells. There's adequate and substantial amounts of drug in that cell to be able to engage the machinery and ADAR. We see that in the concept of if you put more substrate into the cell, you can generate a lot more protein.
Got it. Thank you.
Our next question comes from Yun Zhong with Wedbush Securities. Please unmute your audio and ask your question.
Hi, good morning. Thank you very much for taking the question. I just want to confirm that when comparing data from single dose cohort versus repeat dosing cohort, the biggest impact is really the increase in M-AAT protein level instead of total AAT protein level. It doesn't seem to be quite the same as what you probably saw from preclinical data because the mouse continued to show increase in total AAT level as well. Is that a correct observation, please?
Yeah, I mean, I think if we step back and look at these data with M protein substantially increasing, Z protein substantially decreasing, that is the definition of what editing is supposed to do, right? Editing is derived to take the substrate that's inside the cell and correct it from Z to M. We see highly efficient, highly durable editing. I think as we look between the mouse to humans, we have to think about some of the implications of where those models are in terms of what substrate available for editing is. Knowing that we've got a stable, durable construct that in the animal model could drive that and see, as you said, we could continue to see more.
I think what's important here on highlighting what we can continue to see over more is we do believe that the trend in total, the trend in M should increase over time, like we saw in the model. The model in mice is obviously, I would say mice are faster, so the time horizon is more expedient. What we saw in the mouse was that actually we decreased aggregates in the liver. Again, demonstrating now Z protein substantially decreasing means we should be decreasing aggregates and buildup in the liver. That creates healthier hepatocytes. Those hepatocytes should be more functional in terms of producing protein. You get rid of the residual Z polymers. Essentially, the process gets more efficient. That's what we saw in the mouse model over time.
Given that what we see now in patients, which is this decrease in Z, substantial increase in M, it's reasonable to expect that with time too, those same features take place, right? You're improving ultimately hepatic health.
Would you expect a higher editing efficiency, say, with 600 mg?
I mean, that's exactly right. Yes. As we say, the difference between M, even between single and multi, the amount of M, that's the editing efficiency. The edited protein goes up and continues to go up over time. If we stop the study to do follow-up, it was still trending. If we see, again, at the 400 mg, we have another opportunity to see with multi-dose continued trend on editing going up on M protein. As you said, 600 mg. I think that's the piece to follow is that editing efficiency over time with M.
Great, thank you.
Our next question comes from Catherine Novack with Jones Trading. Please unmute your audio and ask your question.
Hi, can you hear me?
Yes.
Okay, great. Just trying to think about what is the scope of this study before turning the program over to GSK. You mentioned most of the patients were F0, but if there's a handful of patients who have some liver fibrosis, would you have the opportunity to look at improvement so that we can get beyond this focus on biomarkers between RNA and based editing and really look at some clinical outcomes?
Yes. If we think about the totality of this study, this study is designed to be that exploratory phase I/II study that's going to give us insights into the biology. Obviously, today we opened up a whole new portion of biology for actual treatment of MZ patients as it relates to response during those acute phase responses. As you point out, with having patients where we didn't have to exclude patients with pre-existing liver disease, it gives us opportunities to do biopsies and others over the course of the study to be able to do additional work as we evaluate patients through the cohort, particularly as we get to the highest dose cohort. We're in the middle dose now with the 400 mg monthly, one more higher dose to explore that lets us evaluate pharmacology and frequency.
It also just gives us an opportunity to continue to gain insights into what's happening in the liver and with editing. I think it's set up for us to be able to explore that.
Okay, great. Thanks.
Our next question comes from Madison El-Saadi from B. Riley Securities. Please unmute your audio and ask your question.
Hey guys, thanks for taking our question today. I just wanted to ask, why go from 200 mg biweekly to monthly in the 400 mg arm? Just wondering what drove that decision. Should we expect monthly dosing in the higher dose cohorts, or has that decision been made yet? Secondly, I guess maybe what's really driving the temporal change? How much of this is GalNAc, pharmacodynamic related versus editing efficiency related things?
Chris, I can take the first part of that question. Based on the data that we've seen today, and as I showed earlier today, there's quite a long tail to the editing. In the multiple dose, after you stop dosing, we have great editing that continues to be 50% edited out to two months after follow-up. We also have our 400 mg single dose data. Using that data, as well as some of the modeling, that supported moving forward with the 400 mg dose on a monthly basis. It's possible that we could have even less frequent dosing based on the PK we're seeing. That's part of the reason why we want to go forward with that 400 mg once monthly dosing. We'll consider what to do in that third cohort as the data comes in that might help us to support less frequent dosing than once monthly.
I think the second part of your question just builds on that, which is, you know, GalNAc is efficient at drug end, right? It gives us highly efficient drug access to the cell. It's all of the other chemistries that we've been driving as we think about PN and stability that allow us, as we're repeat dosing, to have a substantial amount of stable, durable drug inside the cell with which to continue to edit. That allows us to have two things. One, that durability and that less frequent administration over time, because you're actually continuing to accumulate. I think even as we give monthly, we'll continue to see that as we saw with M protein continuing up between just the 200 mg SAD and MAD. I think it's going to be interesting with more drugs sitting there.
Most importantly, and kind of getting back to this dynamics question, it's the fact that the uniqueness of the stability of the drug that's in the cell, right? If the drug wasn't stable, it wouldn't be there to meet the acute phase responses when they happen. Having really stable drug infrequently means that the drug's in the cell, it's poised to engage both the enzyme and a transcript in terms of editing. It can rise to meet that occasion wherever it comes. It really does get back to the chemistry beyond just GalNAc that gets you in, that drives that stability, the durability, and ultimately enables the dynamic response.
Got it. That's helpful. Thanks.
Our next question comes from Steve Seedhouse with Cantor Fitzgerald. Please unmute your audio and ask your question.
Hey, good morning. Thanks for the question and congrats on the milestone of really successfully translating safety, efficacy, and consistency, it looks like, of RNA editing into the clinic. I had actually two quick questions. First, can you comment on the LC-MS assay for quantifying AAT, the rationale for implementing that, sort of when it was implemented? It looks like that's potentially new based on the LLQ. Also, can you clarify or confirm if the acute phase response patient was one of the first two that were treated in a 200 mg SAD cohort?
I'll take your last question, and Erik will take the first question on the assay development. Yes, the patient with the acute phase response was in the initial pump patient.
Yeah, on the LC-MS assays, it's correct that we didn't have the C assay developed in the fall. That's a new addition. We have moved to M and C assays because they're highly sensitive and also highly specific. As we presented in one of the slides, the limit of quantification is very low, below 0.1 μM. They're highly sensitive. That was a move we made because the turbidometry assays, that way of measuring total AAT, have a lot of disadvantages. It's actually not at all sensitive. It's a 10- 100-fold higher LLQ. It's also designed for healthy individuals. It's known to underestimate C levels because it's an immunobased assay that doesn't really see the epitopes. For all of those reasons, we went for a highly sensitive and specific M assay and C assay with LC-MS.
I think just to add to the other point that, you know, as we validated, as Erik Ingelsson said, the validation that was done didn't take into account ZZ, MZ, and MN individuals. These ranges that we're seeing are within the ranges of the validated MZ component. I think it's just important as we test in cohort with the whole, the prior question, which is how do we evaluate editing? Editing is entirely evaluated based on the resolution to be able to see change from Z to M. Having highly sensitive tools with which to be able to quantitate that is critical in developing an editing molecule.
Thank you.
We'll take our last question from Angela Qian with Canaccord Genuity. Please unmute your line and ask your question.
Hey guys, thank you for taking my question. This is Angela on for Whitney. Just wanted to ask, is there a long-term extension cohort here? I don't think we've seen any, but curious if there's been any efforts to open one so patients could roll over and additional repeat dose data could be gathered to maybe capture more of these acute phase responses over time?
Yes, I guess the short answer is yes. There's the opportunity, like for all of our programs, to add on an OLE opportunity. Obviously, a lot of that past this third cohort and where we go is in conjunction with discussions with our collaborator. Yes, I think all of us would love to understand more about longer-term dynamics, particularly as we explore monthly dosing regimens and having longer-term data on frequency and numbers. Those are all opportunities we continue to have to explore long-term editing efficiency and changes ultimately in these proteins. Again, be able to have opportunities to capture more acute exacerbations and test these dynamic effects.
Thank you. That's helpful. Maybe if I could just add a quick one. Has there been any discussion either internally or externally around a serum AAT during the acute phase response as a potential path forward, like capturing that kinetic sensitive potential path?
I mean, it's a great question because we spent time when we saw it. It's like that is the exact threshold that, you know, frankly, isn't studied elsewhere other than in clinical outcome studies to see does it protect. Since we have that, and it's again across a threshold that would be expected at the lower limit of what could be in patient, that's interesting. I mean, we've discussed it. I think the view is we always say that those regulatory conversations happen with a better bit of the totality of the data. The study is ongoing. We're going to have potentially again continued higher levels of M protein editing total. I think establishing that parameter is an opportunity. It is consistent, the CRP response element to MZ, and it's consistent with what you would expect during an acute phase response. I think what we've demonstrated is exactly that.
It'll definitely be part of the discussion with our collaborator GSK as we think about both development paths forward, but also regulatory steps in terms of registration.
Thank you.
Thank you.
Thank you. There are no further questions at this time. I will now turn the call back over to Paul Bolno for closing remarks.
Thank you, everyone, for joining the call this morning. I am grateful to every Wave employee for their dedication and focus on our mission and on the patients and families we serve. Thank you again to the AATD community for your continued support and partnership. Have a great day.