ProQR Therapeutics N.V. (PRQR) Earnings Call Transcript & Summary

Good morning, everyone, and welcome to the ProQR Therapeutics Virtual Investor and Analyst Educational Event. As a reminder, this call is being recorded, and a replay will be made available on the ProQR website following the conclusion of the event. I'd now like to turn the call over to Sarah Kiely, Vice President of Investor Relations and Corporate Affairs at ProQR Therapeutics. Please go ahead, Sarah.

Thank you all for joining us today. We're pleased to present our educational event, NTCP modulation in Biliary Atresia via liver-targeted RNA editing. During this presentation, we will make forward-looking statements, and actual results may differ materially from those described. Please refer to our SEC filings for a discussion of risks associated with an investment in ProQR. Let me now briefly walk you through today's agenda. We will start with opening remarks from our Founder and CEO, Daniel de Boer. Next, Dr. [indiscernible], our Head of Hepatology, will discuss the rationale for NTCP modulation in Biliary Atresia and our recent target engagement clinical data with AX8. We are also pleased to be joined today by Dr. Gideon Hirschfield, a leading hepatologist and professor of Gastroenterology and Hepatology at the Toronto Center for Liver Disease who will provide perspective on this and the role of bile acids in cholestatic liver disease. Dr. Christina Lopez Lopez, our Chief Medical Officer, will then discuss the next steps for our NTCP programs, including our clinical development plans in Biliary Atresia and how we will evaluate the upcoming AX-811 Phase I data. Finally, we will conclude with a Q&A session featuring today's speakers. With that, it is my pleasure to hand things over to Daniel. Daniel?

Thank you, Sarah. I'm Daniel De Boer, Founder and CEO of ProQR, the Lear in ADAR-mediated RNA editing. Through our Axiomer RNA editing platform, we are building a diversified pipeline across a range of diseases with multiple clinical data readouts expected over the next 12 months. Most recently, we reported the first clinical data from our wholly owned program, Axiomer-10. These results represent an important milestone for ProQR, providing the first clinical validation of our Axiomer platform in humans and demonstrating dose-dependent target engagement of NTCP the main hepatic transporter involved in bile acid uptake in the liver. Beyond NTCP, we are also advancing wholly owned programs in MPS I Hurler syndrome and PNPLA3 related MASH. In addition, our strategic partnership with [ Eli Lilly ] as well as our AI-enabled discovery efforts and collaboration with Kingo Bioworks accelerate the potential of the platform. Today, however, we are going to focus specifically on our NCTP programs and what the X80 data tell us about the potential of this approach. AX-A10 has now demonstrated human target engagement of NTCP and AX-811, our next-generation AI discovered anticipate program is designed to build on that foundation with greater potency and durability. Earlier this month, we announced the AX-811 Phase I study is now underway with initial data from the first 2 cohorts expected in early January 2027. These lead programs are being developed to address cholestatic liver disease, and our initial indication is Biliary Atresia, where we believe the biology of bile acid accumulation provides compelling rationale for NTCP modulation. The key question is how the human pharmacodynamics we have now observed with AX-810 may translate into meaningful benefit for patients with Biliary Atresia. Dr. Golnar Karmin ] will now take you through that rationale and data in more detail. Golnar .

Thank you, Daniel. Biliary Atresia is a severe pediatric cholestatic disease that affects approximately 20,000 patients worldwide and is driven by toxic bile acid accumulation in the liver. There are currently no approved pharmacological therapies that alter the course of the disease and recent late-stage trial results underscore the need for approaches that act directly on liver. The current standard of care is early surgical intervention with the Kasai portoenterostomy, which is intended to restore some bile flow. However, Kasai is often not sufficient, and most patients will continue to progress with 60% to 80% ultimately requiring liver transplantation in early childhood. This highlights both the severity of the disease and the urgent need for therapies that can modify disease progression. Our approach aims to selectively modulate NCTP to reduce toxic bile acid reuptake into the liver, lowering bile acid burden to reduce intrahepatic cholestasis. Let's take a closer look at the normal enterohepatic cycle to understand the biology. In healthy individuals, bile acids are continuously recycled between the liver and intestine where they support digestion and absorption of lipids and fat-soluble vitamins. Approximately 95% of bile acids are absorbed from the intestine and return to the liver through blood circulation. NTCP is the main transporter responsible for recycling conjugated bile acids back into hepatocytes. In biliary atresia, however, this tightly regulated system is disrupted because bile flow is impaired toxic bile acids accumulate in the liver and spill over into the circulation by increased activity of MRP 3 and 4 transporters. This leads to an increase in conjugated and total bile acids in plasma. Persistent hepatic bile acid accumulation contributes to ongoing liver injury and intrahepatic cholestasis. Early in the disease, this leads to an increase in liver enzymes such as ALT, AST and gamma GT as well as negative impact on newer function as seen with an increase in plasma bilirubin and other fibrosis biomarkers. In Biliary Atresia, this is associated with worse outcomes, including progression and reduced native liver survival. By modulating NTCP activity via RNA editing, our therapeutic approach aims to decrease the amount of bile acid reentering hepatocytes. Increasing bile acid levels in the plasma and in turn, excretion in the urine of these bile acids. This pharmacodynamic pattern of relieving the burden of toxic bile acids in the liver aims to improve liver health biomarkers and ultimately clinical outcomes. The distinction between plasma and hepatic bile acids is central to understanding both our mechanism and the clinical data I will review shortly. Our in vivo preclinical data set supports this approach. Starting on the left, in an advanced humanized mouse model, AX-811 demonstrates a decrease in hepatocyte bile acid levels by 67%, and showing effective modulation of NTCP-mediated bile acid uptake. There were corresponding reductions in bile acid levels downstream in the bile docs in the middle of the slide and in the portal vein on the middle right. On the far right of the slide, the same model was challenged with a DTC diet, which induces bile duct obstruction and mimics key features of cholestatic liver disease. In that setting Axiomer mediated an NTCP modulation reduced histological cholestasis scores by 67%, as assessed by an independent external histopathologist. Together, these data provide compelling proof-of-concept for the therapeutic mechanism that reducing NTCP-mediated biased uptake via RNA editing can protect the liver from toxic bile acid accumulation and substantially reduce in [indiscernible]Turning now to the clinical data we reported earlier this year with AXA. The first in human Phase I study was designed to assess safety, tolerability and pharmacokinetics and to evaluate biomarker-based target engagement. Healthy volunteers received 4 weekly subcutaneous doses of AX-810, and we assessed target engagement using 3 complementary biomarker approaches. First, we assessed clearance of orally administered [indiscernible] which was intentionally selected because of its preferential NTCP-mediated uptake. Second, we assessed bile acid profile, including conjugated bile acids, which are specifically regulated through NTCP and provide a more direct assessment of the mechanism. And third, we measure total bile acids in plasma with reduced NTCP-mediated hepatic uptake, we expected to see a concordant increase in bile acids in circulation. The current data set includes data from cohorts 1 and 2, evaluating the 3 and 6-milligram per kilogram dose levels, respectively. Here are the baseline characteristics, which show nice consistency across groups. Turning to safety. AX-810 has demonstrated a favorable safety and tolerability profile with Cohort 1 and 2 to date. There were no serious adverse events, and we observed no clinically significant changes in liver enzymes. In particular, we noted there was no occurrence of pruritus and no changes in hormone and vitamin D levels. We also saw no changes in bilirubin across cohorts, providing evidence that AX-810 had no off-target effect on OATP, the main transporter of bilirubin as expected with RNA editing. The pharmacokinetic profile was also consistent with our expectations with the available data supporting an estimated half-life of 8 weeks. Turning now to target engagement. We observed concurrent durable, statistically significant and dose-dependent evidence of target engagement across all 3 independent biomarkers. The left and center panels demonstrate the specificity of our approach for NTCP rather than other hepatic transporters. Following an oral challenge, we observed a dose-dependent reduction in plasma to car clearance, providing direct evidence of selective NTCP modulation. The specificity is further supported by the conjugated bile acids shown in the center panel. Now on the right, we observed up to an eightfold increase in serum total bile acids. Consistent with the mechanism we described earlier, reduced hepatic uptake and retention of bile acids in plasma following NTCP modulation. The consistent dose-dependent responses across these 3 biomarkers strengthen our confidence in the robustness of the target engagement data and evidence that AX-810 is engaging NTCP as intended. Looking more closely at the relationship between plasma and renal clearance. The urinary data show that these conjugated bile acids are eliminated through renal excretion in a manner that is directionally aligned with the increase in plasma bile acids. When we relate these findings back to the enterohepatic cycle, this is consistent with the pharmacology we would expect. Rather than accumulating within the hepatocytes, conjugated bile acids in the plasma are redirected toward urinary excretion. Together, these data support the proposed mechanism of action and demonstrate the potential of NTCP modulation with RNA editing to reduce intrahepatic cholestasis. The next question is how this may translate into benefit for patients with cholestatic disease. Continuing our examination of plasma conjugated bile acids. In the disease state, there is a toxic dynamic between bile acid levels in the liver and in plasma, as you can see in the middle graph. The red line shows the level at which accumulation of bile acids becomes toxic and leads to intrahepatic cholestasis. This is associated with deterioration of liver held biomarkers disease severity and worse clinical outcomes. Chronic treatment can do this selectively, while preserving other functions of anticipates such as hormonal and drug transport. This, combined with the durability we are seeing with Axiomer, distinguishes our approach from broader [indiscernible] and from therapies that act primarily in the intestine. Now to help put our findings into a broader clinical and disease context, I'm very pleased to hand over to Professor Gideon Hirschfield who will discuss in more detail the role of bile acids in the p athophysiology of cholestasis and why these changes in bile acids modulation are relevant as therapeutic approach. Professor Hirschfield is a world-renowned expert in the liver disease field, and his research focuses on advancing therapies for liver diseases to prevent the need for transplantation. Professor Hirschfield.

Thank you, Gunnar. My name is Gideon Hirschfield. It's a pleasure to be here today. And what I'd like to do for the next sort of 15 minutes or so is talk to you about the importance of bile acids and intrahepatic circulation in cholestatic diseases. Really, when we think about cholestasis, we really need to take a mechanistic approach to understanding it. And we need to think beyond the fact that cholestasis is the presence of bile in blood and think about the etiologies and the site of the hepatobiliary injury. Cholestasis, in fact, is driven from the hepatocytes through the [indiscernible] into the large bile ducts. And we see hepatocellular injury, small b injury and large bar injury across the spectrum of cholestatic liver diseases that adults and children live with. When we think about the causes of cholestasis, we're therefore able to divide it into intrahepatic and extrahepatic. And here, I demonstrate for you the wide variety of adult and children's diseases for which cholestasis is so important. You'll see that biliary atresia, as an example, has both extrahepatic and intrahepatic cholestasis as dominant features of the disease. Understanding the site and cause of cholestasis helps us as we think about better treatments for people living with these chronic inflammatory and fibrotic and symptomatic diseases. The helicopter view, however, is important to recognize the very close relationship between the liver and the bowl. Indeed, there's a very significant relationship between [indiscernible] biliary ion of conjugated bile acids into the bowel, modification of bile acids by the microbiome to create secondary bile acids. And then an exquisitely sensitive and controlled hepatic recirculation going from the ileoluman into the pool vein and then back into the liver using a number of very important transporters. Bile acids are very important in liver and intestinal disease. This slide from the late Allan Hoffmann, who really was the bile acid pioneer, just highlights for you some of the functions of bile acids and why they're so important. Cholesterol illumination, stimulation of bile flow itself, stimulation of biliary phospho colon secretion feedback inhibition of bile acid and cholesterol biosynthesis and of course, lipid absorption as well as stimulation of intestinal motility. We therefore have an exquisitely sensitive and important part of biology that when injured causes liver damage. But equally, we have the opportunity to use bile acids and bile acid transporters as therapies for our patients. Now trying to understand these diseases has been challenging because frequently, we don't know the exact etiology. On the left, you can see a pictogram, which really applies to sclerosing cholangitis diseases. So that would include primaryclosing cholangitis and biliary atresia, where you can see the importance of genes in the environment, the importance of the immune system, the importance of normal biliarypithelial function to protect itself against acid and then a crosstalk and a progressive fibrosis. Where we've landed is that we have recognized that toxic bile acid accumulation is very important as part of the injurious process. The failed metabolic homeostasis because of different triggers leads to cell stress and cell death, leads to inflammation and leads to fibrosis. And so this opens up opportunities for novel therapeutic strategies to stop the progressive biliary injury and help our patients have no further fibrosis and indeed potentially reverse fibrosis alongside hopefully improving symptoms. Bile acid biology is not separate to immunology, and we now recognize that bile acid metabolites, in fact, control immunoregulation, and we have a number of papers that show this in the gut and gut bacteria are relevant as well and that they produce -- the bile acids can inhibit [indiscernible] cell function, which may be relevant to inflammatory disorders. This is also relevant in the liver itself and not just in the gut compartment. Finally, there's actually some very exciting data just published about how bile acid retention, and you'll remember, that's a fundamental part of cholestatic injury in children and adults. But that bile acid retention, in fact, drives pro-inflammatory programs in macrophages. So in this work just published in the Journal of Experimental Medicine in models of [indiscernible] cholangitis, bile acid laden apoptotic parenchymal cells are changing the program in macrophages such that it drives a pro-inflammatory program, and that contributes to chronic hepatic inflammation. It speaks further to the important opportunity to reduce bile acid retention in the hepatic compartment. Bile acids are very, very complex chemicals, and they have very complex physiology, but equally complex potential toxicity. The primary bile acids from the -- starting from cholesterol and conjugated in the liver, leading to secondary bile acids in the gut with a variety of different deconjugation, dehydroxylation and again, repeat conjugation. And some of these bile acids are particularly toxic. In particular, the natural hydroxy bile acids, hinodeoxycholic acid and deeoxycholic acid bind tightly to an absorbent as a measure of hydrophobicity and are highly cytotoxic. That's unlike ursideoxycholic acid which is considered to be devoid of cytotoxic properties and colic acid is somewhere as an intermediate in terms of toxicity. This means that if we can reduce the toxic bile acids from the correct compartment, we should be able to improve inflammation. So how is the system tightly regulated. The 3 major protein transporters for conjugated violates of NTCP, BSEP and IBA. And you can see how this works in the enterohepatic circulation in this stylized picture demonstrating the cycle of these conjugated bile assets into the liver out the liver and then reabsorb from the gut. Now at a more microscopic and cellular level, you're then able to see on the left how this pathway is interacting with other pathways, which we know to be anticholestatic and which we know have been used for therapies. So on the left, you see the hepatocyte and the [indiscernible] you see this intrahepatic circulation. You see the relationship to FXR and FGF19, and you understand this is one of the homeostatic and then pathophysiological pathways of note in cholestatic diseases. On the right, you start to see the overlay with PPARs, which you'll also know have been shown to be very effective therapies and particularly in adult cholestatic disease and particularly primary biliary cholangitis, where we have a number of ligands for PPA receptors. So this pathway is tightly regulated and interacting with pathways of physiological and pathophysiological relevance. What happens if you have NTCP deficiency. This leads to conjugated hypercholanemia but without a clinical phenotype. As you can see in this original paper of a number of patients with this very, very rare genetic deficiency. You can see that there is biased retention in the systemic circulation but there is no pruritus because serum biases are not the [ peritogen. ] The intrahepatic bile acid levels are low and there's low bile acid levels in the small in testing, but there is no significant liver injury. So here, we have a very selective deficiency of a very key transporter in bile acid recirculation. If we want to then target intrahepatic cholestasis and be novel about our targeting, we then can think about a number of approaches. And clearly, we're going to focus on NTCP inhibition as a highly logical therapeutic target. But other people have talked about systemic IBAT inhibition in terms of the kidney access, synthesis inhibition, inhibition of passive absorption changing BSEP transport capacity, surgical diversion is already practiced. And then we already know a lot about IBAT inhibition as we've seen that as a successful therapy for some other very rare liver diseases. Biliary Atresia represents a highly logical target for NTCP inhibition. Biliary Atresia is a destructive inflammatory process that affects extrahepatic paras that leads to fibrosis, an obliteration of the biliary tree and development of binary cirrhosis. We don't have a log, but we fundamentally understand that it is a chronic cholestatic and progressive disease. We understand that there's a role for genes and environment, immune disregulation. But importantly, there's clear injury and persistent and progressive cholestasis, including after Kasai enterostomy, where intrahepatic [indiscernible] bile acid retention is very important in driving further injury for these unfortunate children. There is a very high unmet medical need for people living with Biliary Atresia. It's a very rare disease. It's a pediatric disease, that patients are symptomatic and they will progress to cirrhosis and portal hypertension. Standard of care is early Kasia's first-line therapy. But after that, there's a very high need for liver transplant in later life. So even though biliary obstruction is overcome with the Kasai, this does not change the progressive intrahepatic cholestasis and the progressive nature of this disease. And that's why Biliary Atresia remains responsible for about 45% of all pediatric liver transplantation. Here, you can see over a number of years that this number hasn't changed. The unmet need is real and important. And there is the opportunity to deliver new therapies. When you look under the microscope and you see what's happening, you can this cholestatic process. There's expansion of the portal track with stromal edema. There's prominent liver fibrosis. There's bile duct proliferation, and there are bile plugs. You can see some of this cholestasis. And therefore, this [indiscernible] liver disease is one where the unmet need aligns with new therapeutic opportunities to use our knowledge of bile acid recirculation to change intrapatic bile acid retention as a potential therapy. When we look at mRNA expression of SLC [indiscernible] which is NTCP in Biliary Atresia, we see that it is significantly upregulated in response to this persistent cholestatic injury. So NTCP expression is high in patients living with Biliary Atresia. So we come to the fundamental hypothesis, the accumulation of [indiscernible] in the liver is a major factor in the pathophysiology of disease. In healthy individuals, we see that bile acid levels in each compartment are tightly regulated, whether that's the liver the blood, the intestine, the kidney. In Biliary Atresia patients, we see consistent increases in bile acids in the liver and the serum. This is toxic bile acids, which are associated with further liver injury. Therefore, NTCP modulation has the potential to lead to the opposite pattern of bile assets between liver and plasma. So we can see that we will aim to reduce the bile acid and retention in the liver. We will move the bile acids into serum and excrete them in the kidney, and we will reduce bile acids into the intestine or keep it at the same level. So if we look at disease versus NTCP modulation in the disease state, the untreated biliary atresia patient, they have very high plasma bile acids, their liver bile acids are very high, and this toxic load is profibrotic and their expected outcome, unfortunately, without liver transplant is mortality. Now NTCP modulation editing therapy to change NTCP function will lead to high plasma bile acids, and we can already show in healthy volunteers, target engagement liver bile acids will go down, and that's been shown in animal models. And that leads to the hypothesis and therapeutic intent that with a decrease in liver bile acid load, there is a potential real opportunity to decrease negative outcomes. With that, I'll now hand over to Christina.

Thank you, Professor Hirschfield. What you have just heard provides important clinical context for the AX-810 data we reviewed earlier. In our first in-human study of AXA, we have demonstrated clear dose-dependent target engagement across 3 predefined biomarkers together with a favorable safety and tolerability profile to date. This data provides the first clinical validation of our RNA editing approach to NTCP modulation. This gives us an important anchor for our NTCP strategy. The next question is how far we can drive that pharmacology, and that is where AX811comes in. Preclinically, AX 811 demonstrates greater potency and longer durability than AX 810, using the same translational framework anchored by the AX 810 human PK data, our modeling predicts approximately 40% editing at the 2-milligram per kilogram dose level, and approximately 65% editing at the 4-milligram dose level. These projected levels of editing are achieved at lower doses than AX-0810. As such, we expect that AX-811 has the potential for lower dose levels and less frequent dosing in the clinic with a product that half-life greater than 3 months. AX-0811 is now in a first-in-human study. We announced the first participant dose earlier this month and initial target engagement data are expected by early January 2027. We AX-0810 provides us with evidence of human target engagement and a clear framework for evaluating AX-0811. We will use the same 3 target engagement measures with a particular emphasis. [indiscernible] will be our most sensitive measure for comparing pharmacodynamic effect, given its specificity for NTCP and the controlled challenged conditions. -- conjugated by asset profile will be important for understanding translation into the disease setting. And total biased will remain an additional supportive measure of target engagement. We expect AX-0811 to outperform AX-0810 in all biomarkers across equivalent cohorts. Then we have a clear path to clinical translation. AX-0810 has shown that we can alter bioacid handling in humans, while our preclinical data show that reducing liver blast uptake can over intrahepatic toxic biased burden and improve cholestasis. Our studies in Biliary Atresia will now test in patients how this can translate into measurable improvements in [indiscernible] with the ultimate goal of preservation of native liver health. An investigator-initiated trial in China will evaluate 2 dose levels in 10 patients, aged 5 to 11 years post-Kasai with her native live. The study will assess safety, PK, target engagement and biomarkers of liver health, including measures such as ALT, AST and GGT liver function and fibrosis biomarkers and never stiffness by ultrasound elastography. We expect interim analysis in the first half of 27 and these findings will help inform our subsequent Phase II program. For the Phase II program, the study is expected to enroll 2 cohorts of post case patients with their native liver. The study will assess improvements in liver health biomarkers as well as clinical outcomes. We are planning an interim analysis after 12 weeks currently expected in mid-2020. We will provide additional detail regarding endpoints and the overall registration pathway at a later date and following regulatory interactions. Bringing this all together, I'd like to leave you with 2 key takeaways from today. First, we will use the same 3 target engagement biomarkers with [indiscernible] with a defined biomarker framework to assess how great a potency and durability translates. Second, we have a clear path to test clinical translation from human anti target engagement to impact on liver health. AX-0810 has shown that we can alter by laced handling in humans via RNA editing and modulation and our preclinical data show that reducing hepatic [indiscernible] can lower liver by lased burden and improve cholestasis. Our BIT will assess how changes in bile acid handling translate into improvement in liver injury enzymes, function, fibrosis and stiffness with a goal of prolonging native liver health. Beyond NTCP, our broader Axiomer pipeline is also advancing with multiple clinical catalysts ahead across our pipeline, including data from X-22 a targeting MPS I Hurler syndrome and [indiscernible] for PNPLA3 related match in the first half of 2027. We we look forward to keeping you updated on our progress. Operator, we'll now take questions.

[Operator Instructions] So our first question comes from Steve Seedhouse at Cantor Fitzgerald.

Great. Thanks so much for hosting the event and for walking through all that. Maybe just real quick, I wanted to check if prior to the early January data update on AX-0811, if you would be sharing the highest dose cohort data for AX-0810 just to sort of look at the continued dose response there? And then maybe a more sort of scientific question. Obviously, you showed the increase in urinary bile acid excretion. Wondering if there would be any expectation for side effects associated with that sort of analogous to the diarrhea that you see with IBAT inhibition when there's an increase in fecal bile acid excretion and on that point, like I'm curious if you actually had a chance to look at the fecal bile acid excretion in Phase I. And if it changes at all either up or down with NTCP inhibition and the corresponding changes you see in serum.

Steve, this is Daniel. Thank you for the questions. So I'll take the first one. For AX0810, as we have communicated before, we'll share the full data on the studies, and it includes third cohort as well as the 12-week follow-up data on all 3 cohorts at a scientific or medical conference later this year. And so that will be ahead of the AX0811 data and that is on track. For your question with respect to the side effects, I'll ask Golar.

Regarding -- you had 2 questions. One was about the side effect of the -- on the kidney. In urinary excretion of bile acids is something that happens also naturally in patients who have cholestasis. And based on the data that is currently available, cholestatic patients often do not suffer from a kidney disease. So we don't expect to upside effects on the kidney. Unlike the [indiscernible] that cause diarrhea by excluding more bile acid through the [indiscernible] .

And just quick, did you -- have you looked at fecal bile acid excretion. I'm curious if it similarly goes up just -- and is the form of elimination from the [indiscernible], that actually goes down because you're lowering the liver levels?

Yes. So Steve, I don't think we've measured that Lucid the data we don't have already here. But it also has to do with the size of the mechanism, right? The IBAT inhibitor blocks the uptake of the ballast back into the blood from the intestine and therefore, the bar assets are cleared through the intestine and up in phases. With the NCB mechanism, they are cleared through the urine as we have also seen in the target engagement study.

Our next question comes from Alec Stranahan at Bank of America.

Great to see the updates today. I guess 2 for me. Your AI-driven design systems projecting, I think, 40% to 65% editing efficacy more efficiency versus 0810. So just trying to think through whether that gap will translate 1:1 to the human PK/PD data that you're expecting? And how might a big efficiency job maybe change the dosing frequency you'd be targeting in the Phase II? And then maybe one for Dr. Hirschfield, if he's still on the call. Any important treatment-related adverse events you'll be tracking that could arise from blocking some of the other functions of maybe hormone transport for growth or drug transport for other medicines, these kids may be taken just trying to think about additional data points that could validate the specificity of a procures approach.

As I look for the question. So with respect to the 811 molecule that's now in the clinic, the fast fuller molecule ran that indeed in preclinical studies showed about 6x higher editing efficiency -- we do expect that to translate into human in hopefully, a similar way. We've seen that when we correlated the 10 data back from the clinic to the lab, to the annual models that were used, we saw a really good correlation of the PK and linking that to the editing efficiency allowed us to then extrapolate what the editing efficiency in human would be for AX-0811. And we do anticipate that at the lower doses, so the 2-milligram per kilogram and the mere kilogram the editing efficiency in human will be 40% and 65%, respectively. So we're looking forward to see what that will lead to in terms of biomarker responses. We have also shared earlier that AX-0811 has a significantly extended half compared to 0810. And with that in mind, we do expect that, that molecule will have a less frequent dosing regimen. We currently anticipate it to be less frequent than once every quarter. For your second question, I'll refer to Dr. Hirschfield.

Yes, thanks for the question. I think it's a good question. I suppose I frame it in a number of ways. One is that there are a few families in the world who, of course, don't have NTCP function. And in those patients, they actually have a very benign clinical phenotype, which is reassuring including no liver renal injuries and no itch. The mechanism here, of course, is meant to be selective, but I'm sure the sponsor will be interested in following pruritus I think given the role of bile acids fat-soluble vitamin absorption in these patients, I think will be relevant to be following fat-soluble vitamins. And I'm sure they'll be interested to check there are not more nary tract infections and equally no other hormonal or growth-related concerns. But I don't think that -- the study is going to be overly burdened so more complex in that regard. I think the concept is quite clear, prevent intrahepatic toxicity from bile acids move the toxicity from one compartment into a different compartment and therefore, preserved liver function. And you wouldn't predict beyond what we've already talked about in the other predictable treatment adverse events.

Our next question comes from Costas Biliouris.

And the helpful overview here. A couple of questions from us for Professor Hirschfield. The first one is what would you like to see in the first readout in patients across the different liver function, fibrosis and stiffness end points to feel comfortable with the drug effect here. Is there a specific biomarker or endpoint, you are watching in patients to assess the effect? And the second question is -- from a physician perspective, can you talk a little bit about the potential advantages of a treatment that requires an infrequent injection compared to a treatment that requires daily peers in the pediatric population?

Yes, very good question cost us. I mean I think then in an early phase study beyond safety and the same pharmacokinetics that you've seen. We're going to be looking at liver enzymes. And in children, you're probably going to be focusing more on gamma GT and transaminases. Alphos is complicated with growth. I think we'd like to see, as we've seen in other cholestatic liver disease trials. Sometimes you can pick up changes in proceed fibrosis, and you can also pick up changes actually in the e.l.f. test. So I think there's enough in the simple part of the things that we measure in a clinical trial to get very early signals that effective protection of this hepatocyte that is being mentalized damaged by the retention of toxic bile acids does lead to changes in serve liver tests and fibrosis markers. And I think that will then neatly dovetail with the reproduction of the Phase I data in these kids when they get the drug. I don't actually think it's hard for patient sell to think about a drug that you talk every 2 to 3 months. The biggest challenge is adherence in therapies, particularly in children, particularly as we transition them. Here, you have the opportunity to have highly targeted rational therapy, in vivo adjustment of protein function -- and then for the patient or the patient caregiver to only need to administer every 2 to 3 months. That would be a massive step forward in Biliary Atresia and ultimately in other colystatic liver diseases. Particularly if it's highly predictable and at least the Phase I data is really encouraging as to the site moving quite quickly into humans and into the clinic.

Our next question comes from Gavin Clark-Gartner at Evercore.

This is Issy on for Gavin. Super helpful. Two questions from me. one, I was wondering for the biliary atresia of this disease. How much of the ongoing disease can still happen after this Casa procedure like that is still driven by this intracellular bile acid exposure versus some other already happened inflammation or some duct injury. So because I thought IIT trial, the patients enrolled are like 5% to 11%. So just wondering at that age, how much fibrosis or other disease [indiscernible] be like reversible through this bile acid unloading. And the second question is also like disease biology related. So in the patients with stellar trace NTCP expression upregulated because we see previously in healthy volunteer, we've been targeting like a twofold increase in total sell acid as a relevant biomarkers. So if patients already see this upregulated and NTCP expression, should we expect to see a higher level of the bioassay change to anchor to the potential clinical benefit?

I'm happy to address the clinical question. I think the science can answer the second question. Remember that elutes remains the leading cause of liver transplant despite Kasai port enterostomy and whilst, of course, the timing of [indiscernible] is very important in outcome for Biliary Atresia. The majority of these patients are ending up with secondary biliary cirrhosis from progressive [indiscernible] injury over time, and that's why they end up needing a liver transplant to prolong their life. So I don't I don't foresee that the concept that Kasai does not take away the cholestatic injury and it doesn't change the fact that the hepatocytes in kids at Biliary Atresia are retaining too much bile acid and we believe that, that hepatocyte bile acid retention is driving some of the toxicity and the progression of the disease. So you're right, there is always heterogeneity in all of these rare diseases. And that would be something to be really thought about in later-stage clinical trials. But in the early phase of moving into disease, I think you can be confident that patients are cholestatic that they are retaining too much bar assets, and you should be able to get the early proof of concepts in terms of efficacy from the broad trial design that you've heard.

And for the second question, broadly for Axiomer RNA editing, higher expression of the target typically leads to better editing efficiency. So yes, we anticipate that higher expression of the NCP in Biliary Atresia patients will be favorable for the editing efficiency. Golmar, can you comment on what effect it will have on the disease biology?

Yes. So in these patients, because already they have a high level of the bile acids in the serum due to their cholestatic situation. having at baseline higher NTCP expression means that they are exposed to also higher [indiscernible] now when we have a better target engagement because of the higher expression of the NTCP, we have also a better chance of reducing the intrahepatic cholestasis specific in Biliary Atresia. So how we should look at it. It's not about looking how much we increase the bile acids in the serum compartment up, but how much we will reduce the intrahepatic cholestasis and how much we improve the liver health biomarkers and that is, I think, the results of this higher chance of target engagement.

Our next question comes from Catherine Novack at Jones Trading.