ProQR Therapeutics N.V. Aktie

Good morning, everyone, and welcome to the ProQR Therapeutics Virtual Investor and Analyst Educational Event. [Operator Instructions] 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. Golnar Karimian, our Head of Hepatology, will discuss the rationale for NTCP modulation in biliary atresia and our recent target engagement clinical data with AX-0810. We are also pleased to be joined today by Dr. Gideon Hirschfield, a leading hepatologist and Professor of Gastroenterology and Hepatology at the Toronto Centre for Liver Disease, who will provide perspective on this and the role of bile acids in cholestatic liver disease.

Dr. Cristina 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-0811 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 leader 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, AX-0810. 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 Ginkgo Bioworks, accelerate the potential of the platform. Today, however, we are going to focus specifically on our NTCP programs and what the AX-0810 data tell us about the potential of this approach. AX-0810 has now demonstrated human target engagement of NTCP. And AX-0811, our next-generation AI-discovered NTCP program, is designed to build on that foundation with greater potency and durability.

Earlier this month, we announced the AX-0811 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-0810 may translate into meaningful benefit for patients with biliary atresia. Dr. Golnar Karimian 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 NTCP 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 the intestine where they support digestion and absorption of lipids and fat-soluble vitamins. Approximately 95% of bile acids are reabsorbed from the intestine and returned 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 via increased activity of MRP3 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 liver 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-0811 demonstrates a decrease in hepatocytes bile acid levels by 67%, showing effective modulation of NTCP-mediated bile acid uptake. There were corresponding reductions in bile acid levels downstream in the bile ducts 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 DDC diet, which induces bile duct obstruction and mimics key features of cholestatic liver disease. In that setting, Axiomer-mediated 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 bile acid uptake via RNA editing can protect the liver from toxic bile acid accumulation and substantially reduce intrahepatic cholestasis.

Turning now to the clinical data we reported earlier this year with AX-0810. 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-0810, and we assessed target engagement using 3 complementary biomarker approaches. First, we assessed clearance of orally administered TUDCA, which was intentionally selected because of its preferential NTCP-mediated hepatic uptake. Second, we assessed bile acids profile, including conjugated bile acids, which are specifically regulated through NTCP and provide a more direct assessment of the mechanism. And third, we measured 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-0810 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-0810 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 concordant, 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 TUDCA clearance, providing direct evidence of selective NTCP modulation. This 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-0810 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 health biomarkers, disease severity and worse clinical outcomes.

By selectively reducing hepatic uptake through NTCP modulation, as shown on the right, RNA editing can prevent conjugated bile acids transport from the serum into the liver, protect the liver from toxic conjugated bile acids with the goal to prolong native liver health. For chronic treatment, it is also important that we can do this selectively while preserving other functions of NTCP such as hormonal and drug transport. This, combined with the durability we are seeing with Axiomer, distinguishes our approach from broader NTCP inhibition 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 pathophysiology 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, Golnar. 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 cholangiocytes into the large bile ducts. And we see hepatocellular injury, small bile injury and large bile 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 bowel. Indeed, there's a very significant relationship between biliary secretion 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 ileal lumen into the portal 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 Alan Hofmann, 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 elimination, stimulation of bile flow itself, stimulation of biliary phosphocholine 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 primary sclerosing cholangitis and biliary atresia, where you can see the importance of genes and the environment, the importance of the immune system, the importance of normal biliary epithelial 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 Th17 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 primary sclerosing 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 [indiscernible] 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 dihydroxy bile acids, chenodeoxycholic acid and deoxycholic acid, bind tightly to an absorbent as a measure of hydrophobicity and are highly cytotoxic. That's unlike ursodeoxycholic acid, which is considered to be devoid of cytotoxic properties and cholic 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 bile acids are NTCP, BSEP and IBAT. And you can see how this works in the intrahepatic circulation in this stylized picture, demonstrating the cycle of these conjugated bile acids into the liver, out of the liver and then reabsorbed 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 anti-cholestatic and which we know have been used for therapies.

So on the left, you see the hepatocyte and the enterocyte. 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, particularly in adult cholestatic liver disease and particularly primary biliary cholangitis, where we have a number of ligands for PPAR receptors. So this pathway is tightly regulated and is 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 bile acid retention in the systemic circulation, but there is no pruritus because serum bile acids are not the pruritogen. The intrahepatic bile acid levels are low and there's low bile acid levels in the small intestine, 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 axis, 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 bile ducts that leads to fibrosis and obliteration of the biliary tree and development of biliary cirrhosis. We don't have an etiology, 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 dysregulation. But importantly, there's clear injury and persistent and progressive cholestasis, including after Kasai portoenterostomy, where intrahepatic cholestasis 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. The patients are symptomatic, and they will progress to cirrhosis and portal hypertension. Standard of care is early Kasai as 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 see this cholestatic process. There's expansion of the portal tract 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 cholestatic liver disease is one where the unmet need aligns with new therapeutic opportunities to use our knowledge of bile acid recirculation to change intrahepatic bile acid retention as a potential therapy. When we look at mRNA expression of SLC10A1, 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 that accumulation of bile acid 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 acids between liver and plasma. So we can see that we will aim to reduce the bile acid 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 Cristina.

Thank you, Professor Hirschfield. What you have just heard provides important clinical context for the AX-0810 data we reviewed earlier. In our first-in-human study of AX-0810, we have demonstrated clear dose-dependent target engagement across 3 predefined biomarkers, together with a favorable safety and tolerability profile to date. This data provide 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 AX-0811 comes in. Preclinically, AX-0811 demonstrates greater potency and longer durability than AX-0810. Using the same translational framework anchored by the AX-0810 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-0811 has the potential for lower dose levels and less frequent dosing in the clinic with a projected 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. 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. TUDCA will be our most sensitive measure for comparing pharmacodynamic effect given its specificity for NTCP and the controlled challenge conditions. Conjugated bile acid profile will be important for understanding translation into the disease setting and total bile acids 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 bile acid handling in humans, while our preclinical data show that reducing liver bile acid uptake can lower intrahepatic toxic bile acid burden and improve cholestasis. Our studies in biliary atresia will now test in patients how this can translate into measurable improvements in liver function 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 their native liver.

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 liver stiffness by ultrasound elastography. We expect interim analysis in the first half of 2027, 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-Kasai 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-2028. 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 AX-0811, with a defined biomarker framework to assess how greater potency and durability translates. Second, we have a clear path to test clinical translation from human NTCP target engagement to impact on liver health. AX-0810 has shown that we can alter bile acid handling in humans via RNA editing and modulation and our preclinical data show that reducing hepatic bile acid uptake can lower liver bile acid burden and improve cholestasis. Our BA IIT 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 AX-0422 targeting MPS I Hurler syndrome and AX-2911 for PNPLA3-related MASH in the first half of 2027. 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.

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 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. I'm 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 AX-0810, we -- as we have communicated before, we'll share the full data on that study, and that includes the 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 AX-0811 data, and that is on track. For your question with respect to the side effects, I'll ask Golnar.

For -- regarding -- you had 2 questions. One was about the side effect of the -- on the kidney. And 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 have side effects on the kidney, unlike the IBATs that cause diarrhea by excreting more bile acid through the feces.

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

Yes. So Steve, I don't think we've measured that, at least the data we don't have already here. But it also has to do with the site of the mechanism, right? The IBAT inhibitor block the uptake of the bile acids back into the blood from the intestine. And therefore, the bile acids are cleared through the intestine and end up in feces. With the NTCP mechanism, they're 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 system is projecting, I think, 40% to 65% editing efficacy or 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 jump maybe change the dosing frequency you'd be targeting in a 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 NTCP, maybe hormone transport for growth or drug transport for other medicines these kids may be taking? Just trying to think about additional data points that could validate the specificity of ProQR's approach?

Thanks, Alec, for the question. So with respect to the 0811 molecule that's now in the clinic, the fast follower molecule for NTCP, 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 0810 data back from the clinic to the lab to the animal 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 4-milligram per 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-life compared to 0810. And with that in mind, we do expect that, that molecule will have a less frequent dosing regimen. We currently anticipate that to be less frequent than once every quarter.

For your second question, I'll defer 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 or 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 it will be relevant to be following fat soluble vitamins.

And I'm sure they'll be interested to check there are not more urinary tract infections and equally no other hormonal or growth-related concerns. But I don't think that the study is going to be overly burdensome or 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, preserve liver function. And you wouldn't predict beyond what we already talked about any other predictable treatment adverse events.

Our next question comes from Kostas Biliouris.

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 endpoints 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 pills in this pediatric population?

Yes. Very good questions, Kostas. I mean, I think that 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. Alk phos 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 PRO-C3 fibrosis and you can also pick up changes actually in the ELF 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 compartmentalized damaged by the retention of toxic bile acids does lead to changes in serum 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 [ cell ] to think about a drug that you took 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 it every 2 to 3 months. That would be a massive step forward in biliary atresia and ultimately in other cholestatic liver diseases, particularly if it's highly predictable and at least the Phase I data is really encouraging as to the science moving quite quickly into humans and into the clinic.

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

This is [indiscernible] on for Gavin. Super helpful. Two questions from me. So one, I was wondering for the biliary atresia disease, how much of the ongoing disease can still happen after this Kasai 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 the IIT trial, the patients enrolled age are like 5 to 11. So just wondering, at that age, how much fibrosis or other disease phenotype can be like reversible through this bile acid unloading?

And the second question is also like disease biology related. So in the patients with biliary atresia, is NTCP expression upregulated? Because we see previously in healthy volunteers, we've been targeting like a twofold increase in total bile acid as a relevant biomarker. So if patients already see this upregulated NTCP expression, are we -- should we expecting to see a higher level of the bile acid change to anchor to see a potential clinical benefit?

I'm happy to address the clinical question. I think the scientist can answer the second question. Remember that biliary atresia remains the leading cause of liver transplant despite Kasai portoenterostomy. And whilst, of course, the timing of Kasai portoenterostomy is very important in outcome for kids with biliary atresia, the majority of these patients are ending up with a secondary biliary cirrhosis from progressive cholestatic injury over time, and that's why they end up needing a liver transplant to prolong their life. So I don't foresee that the concept that Kasai does not take away the cholestatic injury and doesn't change the fact that the hepatocytes in kids with 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 the patients are cholestatic, that they are retaining too much bile acids 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.

Thank you. 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 NTCP in biliary atresia patients will be favorable for the editing efficiency.

Golnar, can you comment on what effect that 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 intrahepatic cholestasis. 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, specifically 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 JonesTrading.

I have one for Dr. Hirschfield again on biliary atresia. Just curious about the etiology of biliary atresia with regard to the IIT, which I believe is going to be conducted ex U.S. Are there any geographic differences in causes and triggers of BA that might -- we should be aware of that might complicate the translation of ex-U.S. data to U.S. patients or European patients? Any color you can give on geographic differences would be helpful.

I think the simple answer is no. I think the complex answer is, of course, this is a combination of genes and environment, and there's been lots of different hypothesis about which is dominant. But we've never really come up with a conclusion about where is this window of exposure probably for the babies in utero that triggers what then becomes a progressive fibro-obliterative cholangiopathy. So clinically, the patients are behaving the same once they've got the clinical diagnosis of biliary atresia. So long as the sponsor, which I'm sure they will, is working with the appropriate expertise in pediatric hepatology to make the diagnosis correctly and exclude the other cholestatic liver diseases, which is not easy to do, but is very doable and there's a very clear structure to diagnosing biliary atresia as opposed to, say, Alagille's or other genetic cholestasis or other concerns. And I think the clinical phenotype is consistent between the U.S. and ex U.S. But it's a good question.

Our next question comes from Sushila Hernandez at Kempen.

So we were just wondering whether you can give more color on continuing either 0810 or 0811, also considering your expectations of 0811 and which factors or data might impact that decision?

Sushila, thank you for the question. So yes, we are expecting the AX-0811 initial data readouts to the first 2 cohorts of target engagement data in early January. That data will finalize the decision if it will be 0810 or 0811 that we'll use in the IIT that we will run in biliary atresia. And then likely that same molecule, we will take forward into the Phase II in biliary atresia. So that will be driven by that data readout. Having that said, based on the preclinical data, we see that AX-0811 is much more potent. So our expectation is that AX-0811 will move forward into those next steps.

Perfect. And if you could also give some color on how that would inform or like the Chinese investigator-initiated trial, how that would inform a subsequent Phase II design or how you see its role alongside the development?

Happy to. I'll have Cristina Lopez Lopez, our Chief Medical Officer, address that.

Thank you so much for the question. So as we presented, we have 2-step approach. On one side, we have the investigator-initiated trial where we are moving from healthy volunteers into a children pediatric indication, 5 to 11 years. This will give us a lot of information regarding PK/PD safety and tolerability, and this will totally inform the Phase II that we're planning to do. In the slide that I presented, I mentioned that we have like 2 groups, 2 cohorts. So we are planning to go to infants below 2 years old. And we are discussing with regulators how this study could look like to ensure that we have meaningful outcomes moving forward. And in terms of the endpoints that we're going to be looking at, we're going to really look at the liver health combined with biochemical biomarkers, imaging biomarkers and also hard clinical outcomes.

Our next question comes from Ryan Deschner at Raymond James.

For Dr. Hirschfield, after the Kasai procedure is done in your patients, in cases where it's successful, do you consider the cholangiopathy component to be largely solved? In other words, what does the ceiling look like in terms of what an effective NTCP inhibitor could theoretically deliver to BA patients? And then also I was curious specifically why bulevirtide, for example, as an NTCP inhibitor hasn't been used off-label in biliary atresia patients. Is it more of a therapeutic window issue or something more specific to its interaction with NTCP versus 0810, 0811's mechanism?

Well, I'll answer it backwards. I mean, clearly, NTCP, there are many people thinking about NTCP in cholestatic liver disease. So this approach is more unique and more targeted and more transformational, but there are other sponsors who've obviously done exactly -- who thought exactly as to your point about what would be the role in different cholestatic liver diseases. I think bulevirtide is just not accessible. So no one's actually realistically given it and to give it to a child, I think, would be very difficult when it's not really used in children. We don't use it for delta hepatitis, which is treated in adults.

I think you're then alluding to -- and I'm an adult physician, not a pediatric physician. So I don't claim to have all knowledge about biliary atresia. But I think what you're saying is can we predict who does badly after Kasai. And there are features biochemically and sort of liver stiffness and growth and bile acid levels that can be used to identify the patients who are not going to get the best outcome from a Kasai. But is it possible in any of these rare diseases to get rid of heterogeneity? No, of course not, because there's a window when you make the diagnosis and then get the kid to have the Kasai portoenterostomy. And so that must be an area of heterogeneity. And that must contribute to why some kids rapidly progress despite the Kasai and other kids are living into their teens, but then running into end-stage biliary cirrhosis and needing a liver transplant late.

So it's fair to say that going beyond the proof of concept will require extra attention to the heterogeneity. I don't think it's particularly relevant in the early phase of proof of concept. But as with any sort of complex rare disease, the next steps will require careful sort of alignment of patient phenotyping to really choose the bigger population to prove your ultimate efficacy.

Our next question comes from Jon Wolleben at Citizens.

Along the same lines, I was hoping for a comment from Dr. Hirschfield and management. How are you thinking about a potential registrational path here in BA? Do you think outcomes will be necessary? Or are you going to be proposing some composite biomarker endpoints? And for Dr. Hirschfield, if it's not outcomes, what would you want to see that would be most convincing either singularly or in a composite?

Dr. Hirschfield, if you could go ahead to address the question and then the second part for Cristina, please.

I mean, it's a great question, and you know we're highly vexed of it in the adult world. I think there's a little bit more leeway in the pediatric world for these ultra-rare diseases where clearly, the regulators recognize the incredible obstacles to doing outcome studies, which will take a long time and are very -- clearly would be impossible to do placebo-controlled without access to registry data. So I would imagine that there will be a lot of opportunity to look at registry data, to look at real-world data and comparators.

And whilst, of course, we'd like to show liver transplant-free survival, I think other things such as stabilization of bilirubin, stabilization of liver stiffness, growth trajectories for children, frequency of clinical advancement to end-stage liver disease would be probably opportunities to try and overcome, as you point out, what is a complex regulatory pathway for ultra-rare diseases with slow progression, heterogeneity, inability to do placebo. But I think there will be a willingness from regulators, particularly in the pediatric setting to take that on collaboratively.

And we will learn a lot when other sponsors publish their data on their efforts in biliary atresia. So although we're aware that an IBAT was tried in biliary atresia, what we're not aware of is all the data that will come from that study, which I think will inform the community to do a better study. So it may not have worked for that drug, but it may actually still help the field as a whole.

Yes. I would like just to echo what our colleague, Gideon just mentioned. And this is exactly the path that we would like to move forward in partnership with the regulators. So at the moment, obviously, we are thinking about the hard clinical outcomes, but based on the clinical outcomes, we know that it may take a long time, et cetera. But we are really looking at many different outputs that go at 3 levels. A, clinical outcomes that relate to health resource utilization, meaning native liver survival, hypertension -- portal hypertension. We are thinking about imaging biomarkers or ultrasound biomarkers when we're thinking about fibrosis and when we're thinking about liver stiffness.

And we're also looking about biochemical biomarkers when we're thinking about liver health. So our current conversations that we're going to do with health authorities across the 3 different regions, U.S., Europe and also Asia will rely potentially on a composite to ensure that we can capture the entire value of this drug. And I think that this is very much aligned with our colleague that just presented today.

Our next question comes from Keay Nakae at Chardan.

With respect to AX-0422 for Hurler's and 2911 for PNPLA, when you report that initial data, can you give us a little more color on what you might report for each of those?

Okay. Keay, thanks for the questions. So AX-0422 for MPS I, we have earlier said that we expect initial clinical data by mid next year. That's on track. There's no changes to that guidance. And that will be the usual endpoints for MPS I. So it's typically GAG reductions as a biomarker after subcutaneous administration of AX-0422 in the first cohort. AX-2911 is targeting PNPLA3, which is a genetic driver in certain subgroups of MASH, particularly lean MASH. There, we'll look at a whole range of different liver health biomarkers and imaging. And more detail on that is to come. We've earlier said that, that program will start clinical studies in the first half of next year, and that guidance is still on track.

Our final question comes from Ananda Ghosh at H.C. Wainwright.

One question for Dr. Hirschfield. I just wanted to dig more deep into his comment on the heterogeneity issue and how does it -- and how would he think a potential design might include the variability issue with the heterogeneity in a Phase II study?

It's a good question. And again, I don't claim to be a pediatrician, but I think what pediatricians are looking for is what's happening to the patient's bile acid levels, what's happening to their serum liver tests and what's happening to them then clinically. And I think it will be important in the design of the investigator-initiated to only have patients who've got active cholestasis because clearly, that will be -- to be very important. And at the same time, not to have patients who've crossed the line to too advanced disease with deep jaundice and are too sick to benefit because the liver's failed. And therefore, you don't have the opportunity to use your compartmentalized approach to treatment.

So I think that's how it's going to be tackled at a practical level. And I think as long as it's tackled that way and the patients enter with active cholestasis, then you're going to get the information that you want very quickly because of the encouraging Phase I data suggesting very effective target engagement as to whether or not adjusting NTCP function selectively as this therapy does, it drives down the cholestatic injury one would predict very quickly.

Great. Maybe one follow-up question. Given BOLD missed on native liver survival despite bilirubin being accepted prognostic bridge, like do you still consider bilirubin as an adequate surrogate for BA?

Yes. But I mean, of course, it's an adequate surrogate. I mean, I think what BOLD teaches us is that there's some unrealism from the regulators. But equally, you have to have a drug that's very effective. So one of the challenges in all these discussions that we have is that when we do suddenly bring in really, really targeted, highly effective rational therapies, then some of the challenges that we face with drugs of less efficacy will disappear. I think it's just the fact that any outcome study in liver disease and any outcome study of rare liver disease and any outcome study of rare pediatric liver disease is an incredibly high threshold for the regulators to be looking for. And many of you will know that even in PBC and PSC in the adult world, it causes us lots of angst and discussion and disconnect between the investigators and the regulators.

So this concludes the Q&A session for today and also the virtual investor and analyst educational event. We thank you all for joining, and you may now disconnect.

Good morning, and welcome to the ProQR Therapeutics Virtual Investor and Analyst Event. [Operator Instructions]. 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. Please go ahead, Sarah.

Thank you, and good day, everyone. We appreciate you taking the time to join us today. I'm Sarah Kiely, Vice President of Investor Relations and Corporate Affairs at ProQR. Before we begin, I'd like to briefly walk through today's agenda and introduce our speakers.

We will start with opening remarks from our CEO, Daniel de Boer, who will provide an overview of our pipeline and recent advances. Following that, our Chief Medical Officer, Dr. Cristina Lopez Lopez, will discuss AX-0810, including a reminder of our ongoing Phase I healthy volunteer trial, expectations for the upcoming target engagement readout as well as an overview of our initial indication selection.

Next, our Chief Scientific Officer, Gerard Platenburg, will present updates on our platform and discovery efforts, including the introduction of new pipeline programs and recent preclinical data across our pipeline.

Cristina will cover the corresponding development plans and clinical strategy for these programs. We'll conclude with remarks from our Chief Financial Officer, Dennis Hom, followed by Q&A with covering analysts and our management team. We're looking forward to sharing these updates with you today. Today's event is being recorded, and a replay along with the presentation slides will be available on our website following the event.

Before we get into the program, please note the forward-looking statements on Slide 3. During today's presentations, 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 these risks. I will now turn the program over to Daniel. Daniel?

Good morning, everyone. Thank you all for joining our investor and analyst event. Today, we will share a number of important and exciting updates across our pipeline and development strategy, including 2 new programs and multiple clinical data readouts within our current runway. To start with our lead program, AX-0810 for cholestatic diseases, the trial execution is going according to plan, and we remain on track to report target engagement data from healthy volunteers later this quarter.

This is a key milestone for ProQR, where we expect to demonstrate target engagement on bile acid transport, which is the key driver in cholestatic diseases. Cristina will briefly review this trial and also announce that we have selected biliary atresia as the initial indication for Phase II development.

We will also share how we are advancing the platform with our AI-enabled discovery engine. Over the last 18 months, we have built an AI model that enables us to accelerate discovery and generate improved RNA editing medicines. To further scale this capability, we have announced a strategic partnership with Ginkgo Bioworks, which enables roboticized high-throughput data generation to feed our AI-enabled drug discovery.

In addition, we have established an AI advisory board with leading experts in this space to maximize the use of AI and machine learning to deliver medicines for patients. Together, the AI-guided model, the high-throughput screening now enabled with robotics and the external expertise enable us to generate and optimize lead candidates more efficiently and improve editing performance across our programs in a very meaningful way. One example is AX-0811, a next-generation Axiomer editing oligonucleotide that is targeting NTCP.

As Gerard will present today, our AI-enabled discovery engine produced an optimized EON for NTCP with multifold higher editing performance in vivo at lower dose levels. As we are committed to bringing continued innovation forward to patients, we are advancing this program in parallel with AX-0810 in the clinic. For AX-0811, we expect to file the CTA in mid-2026 and initial clinical data is expected by the end of this year. With the involvement of John Maraganore and Martin Maier at ProQR, we're modeling this strategy to the example of Alnylam, who advanced multiple generations of siRNAs targeting TTR in parallel as their platform evolves, a successful business strategy that led to multiple approved drugs for patients.

This program reflects our continued platform innovation and is designed to extend our NTCP franchise over time, building durable therapeutic area leadership. We are also introducing a new pipeline program for Hurler syndrome or MPS1 named AX-0422. This program addresses the high unmet need in liver and CNS in patients with the most common mutation in the IDUA gene. This program originated from our internal discovery efforts and was advanced as part of the partnership with Eli Lilly.

As a result of a portfolio review, ProQR will regain full rights to AX-0422, allowing us to advance it as a wholly owned asset. The Lilly partnership continues to progress very well with multiple programs advancing in the collaboration. AX-0422 for Hurler syndrome is currently in CTA-enabling activities with a CTA filing expected early 2027 and initial clinical data in patients expected in the first half of 2027.

The emergence of the Hurler program offers a unique opportunity to bridge from liver into CNS given its dual tissue biology. This allows us to build on our existing validation in liver and extend Axiomer into CNS in a derisked way, using the same underlying molecule to unlock CNS, which we see as a key area of opportunity for the Axiomer platform.

As a result, we're ordering our CNS programs in a stepwise manner. Therefore, we will continue to work on the RET program and advance it from a stronger and more validated foundation after successful clinical translation of Hurler in CNS. Today, we will also shine more light on AX-2911, targeting PNPLA3 for MASH. Gerard will walk us through the preclinical proof of concept in a relevant animal model, and Cristina will outline the clinical development strategy. Taken together, this reflects progress across our portfolio with AX-0810 as our lead program, our commitment to cholestatic disease with a focus on biliary atresia and our continued innovation across our platform and pipeline.

Within our current runway, we now expect to generate multiple clinical data readouts across the pipeline. We're excited for the upcoming AX-0810 clinical data and the broader pipeline progress. I will now hand it over to our Chief Medical Officer, Cristina, to discuss our programs after a brief refresher on AX-0810. Cristina?

Thank you, Daniel. I will start with AX-0810, our lead program and first clinical proof point for Axiomer. AX-0810 is ProQR lead investigational RNA editing oligonucleotide targeting NTCP, the key transporter responsible for bile acid uptake from the bloodstream into the liver. By modulating NTCP, AX-0810 is designed to reduce bile acid transport into hepatocytes and thereby limit the toxic bile acid accumulation that drives cholestatic diseases.

Bile acids are produced in the liver and then list the liver through the bile ducts to the intestine. Subsequently, they come back into the systemic circulation and are taking back up into the liver by NTCP. Approximately 95% of the bile acids in the liver get there through NTCP reuptake. In a liver with cholestatic disease and in particular, with biliary atresia, there is an obstruction or an absence of bile ducts, preventing bile acids from leaving the liver.

This leads to accumulation of bile acids in hepatocytes, which causes inflammation and automatic fibrosis. In an attempt to protect itself, the liver activates alternative channels like MSR3, MSR4 and OST alpha, beta to pump bile acids out of the hepatocytes into the bloodstream. This only has a marginal effect as the NTCP channel is continuously taking up bile acids from blood, which maintains the high concentration of bile acids in the liver.

AX-0810 converts wild-type NTCP into the protective Q68R variant. This NTCP variant limits bile acid retake. By limiting bile acid uptake into the cells, the liver has the opportunity to normalize the concentration of bile acids by pumping out bile acids through MSR3, MSR4 and OST alpha, beta which removes the driver of the liver disease. This therapeutic strategy has been demonstrated in multiple cholestatic disease animal models by our collaborator, Professor de Graaf at the Amsterdam University Medical Center.

NTCP was blocked in the cholestatic disease animal models, which led to a two to threefold increase in bile acid in serum as observed on the left and resulted in a normalization of liver weights and fibrosis markers as observed on the right, a robust validation of the therapeutic strategy.

With this mechanism, we believe AX-0810 has the potential to be a disease-modifying therapy, alleviating symptoms and slowing or preventing disease progression. Our ongoing first-in-human study in healthy volunteers is designed to assess safety and tolerability, pharmacokinetics and importantly, biomarker-based target engagement. Earlier this year, we announced that initial data from our first cohort demonstrate a favorable safety and tolerability profile with pharmacokinetics consistent with our nonclinical observations.

A key objective of this study is to demonstrate target engagement through biomarkers. We are using 3 complementary readouts. First, total bile acids in serum, where we expect to see an increase as less bile acids are taking up into the liver. We are targeting a twofold increase as considered a meaningful indicator of NTCP modulation. Second, bile acid profile, which allow us to assess the specificity of the effect, particularly the shift to conjugated bile acids. And third, TUDCA challenge, which provides a functional readout of NTCP-mediated transport by administering a synthetic form of TUDCA and measuring clearance.

Together, these biomarkers allow us to directly measure target engagement, confirm mechanism and inform dose selection. We look forward to reporting target engagement data from the Phase I this quarter. Following the healthy volunteer assessments, we plan to open a cohort in the trial for PSC patients with data at the end of this year.

As part of our development strategy, we are pleased to share today that we have selected biliary atresia as the initial indication for Phase II development. Biliary atresia is a severe pediatric cholestatic disease, affecting approximately 20,000 patients worldwide. There are currently no approved pharmacological therapies that modify disease progression. And despite early surgical intervention, most patients still progress.

In fact, biliary atresia accounts for approximately 45% of all pediatric liver transplants and even with Kasai portoenterostomy, 60% to 80% of patients ultimately require liver transplantation before adulthood. Even with a successful Kasai procedure and liver transplant, patients have a significantly shortened life expectancy. This underscores both the severity of the disease and the lack of effective treatment options to alter its course. Based on this, we have selected biliary atresia as our initial indication for Phase II. There are several key factors that support this decision.

First, as already mentioned, the severity and high unmet medical need. Next, a strong biological rationale. Importantly, this is where Axiomer is uniquely suited. AX-0810 is designed to precisely modulate NTCP function at the RNA level, selectively reducing bile acid uptake into the liver without affecting other functions of the protein. By doing so, we aim to lower bile acid accumulation in hepatocytes, which is a central driver of liver disease.

Also, clinical study execution. Patients are diagnosed early and managed in specialized centers, allowing for efficient study execution and clear assessment of disease progression. Patients with biliary atresia represent a well-defined and relatively homogeneous population, supporting more interpretable clinical outcomes. Finally, a clear development pathway supported by established pediatric regulatory guidance, leveraging liver biomarkers such as diuretic bilirubin, GGT, liver stiffness and the [ PELD ] score to support development and potential accelerated approval alongside clinical outcomes such as transplant-free survival and bilirubin normalization.

Taken together, biliary atresia offer a strong combination of biological rationale, unmet need and development feasibility, including strategic launching considerations. At the same time, we continue to see significant potential in PSC, which represents a larger patient population and remains an important follow-on opportunity where the same mechanism applies.

Overall, this gives us confidence in both the clinical path for AX-0810 and the broader potential of NTCP modulation across cholestatic diseases. In parallel, with the progress AX-0810 is making in the clinic, we are continuing to evolve the platform and expand the pipeline, including next-generation approaches targeting NTCP.

We are now using AI-driven high-throughput screening models trained on 12 years of Axiomer data to develop our next generation of Axiomer, as Daniel noted. This enables us to predict key parameters such as editing efficiency and stability before we even make them. That means we can move faster, reducing time from the discovery process plus the AI keeps learning from every round, getting smarter each time. Here are clear examples of how our AI-enabled discovery process translates into measurable improvements.

What used to take us up to 3 years using manual discovery can now be completed in roughly 6 months, reflecting a significant reduction in discovery time lines, making the process about 90% faster. In addition to speed, we also see improvements in candidate quality, including EONs with up to sixfold increases in editing efficiency compared to the earlier designs. The next generation of EON for our NTP program, AX-0811, reflects the impact of our AI-driven discovery and HTS capabilities. In humanized large models, we see editing efficiencies of around 60% with AX-0811, representing a threefold increase compared to the previous generation, and this is also combined with improved stability.

Together, these data demonstrate how our ongoing platform optimization translates into improved performance at the molecular level. Building on this data, let me walk you through the clinical development plan for AX-0811. The AX-0811 clinical trial design closely mirrors that of AX-0810, featuring ascending doses across multiple cohorts of healthy volunteers. The study will evaluate safety, pharmacokinetics and target engagement. We are advancing this program rapidly with CTA submission expected midyear and initial clinical data by year-end.

This study will also allow us to better understand the relationship between editing performance and biological effect. AX-0810 represents our first clinical validation of NTCP editing. AX-0811 builds on this with our next generation of Axiomer, reflecting continued innovation in editing oligonucleotide design and performance. Together, these programs allow us to build an NTCP franchise over time, similar to, for example, how other RNA-based platforms have evolved across multiple generations of products.

Now let me introduce AX-0422, our RNA editing therapy targeting IDUA for Hurler syndrome, the most severe form of mucopolysaccharidosis type 1 or MPS I. Hurler syndrome is a lysosomal storage disorder affecting multiple organs early in patients' life, leading to significant morbidity and reduced life expectancy. It is caused by mutations in the IDUA gene, resulting in deficiency of the alpha-L-iduronidase enzyme. This results in the toxic accumulation of glycosaminoglycans or GAGs driving the disease pathology.

The most common mutation is a nonsense variant, the tryptophan 402X variant, which is present in up to 60% of patients with a severe phenotype. AX-0422 uses our Axiomer RNA editing platform to directly correct this mutation to wild type at the RNA level, restoring production of functional IDUA enzyme. By doing so, we aim to decrease toxic GAG levels in lysosomes. Current treatment options like enzyme replacement therapy and hematopoietic stem cell transplantation do not fully address all disease manifestations and present some limitations.

As mentioned, Hurler syndrome represents the most severe form of the MPS1 spectrum. Patients present with a range of debilitating symptoms like hepato and splenomegaly as well as neurological impairment. From a biochemical perspective, even a small increase in IDUA enzymatic activity can have a meaningful clinical impact. The attenuated forms, Hurler-Scheie and Scheie have higher enzymatic activity and are associated with a better prognosis.

Looking at current treatment options, there are important limitations. Enzyme replacement therapy can improve some of the systemic symptoms, but does not cross the blood-brain barrier. So it has little to no impact on CNS manifestations. In addition, its efficacy may be reduced over time due to antibody formation against the recombinant IDUA enzyme. Stem cell transplantation can provide some benefit, including effects on neurological outcomes, but it comes with significant risk, requiring specialized centers and suitable donors.

And even after transplant, patients often continue to experience significant disease burden. As such, there remains a clear unmet medical need, especially for therapies that can address both systemic and neurological aspects of the disease. This is where AX-0422 is designed to play a role. In our preclinical data, AX-0422 drives both enzymatic recovery and biomarker normalization. Following subcutaneous delivery, there's a robust restoration of IDUA enzymatic activity in liver, reaching approximately 20% of wild-type levels at 8 weeks. Importantly, this level of restoration translate into meaningful biomarker impact and substantial and dose-dependent reductions in GAG levels on the order of 50% in the liver to almost 90% in the urine compared to control, demonstrating effective toxic substrate clearance.

Taken together, these data show that AX-0422 can achieve levels of enzyme restoration that are within the range expected to drive clinical benefit, along with clear reductions in disease-relevant biomarkers. When comparing RNA editing to standard of care, our data show improved effects in biomarker normalization and functional outcomes. On the biomarker side, we see a great reduction in urinary GAGs over 90% with RNA editing compared to around 60% with ERT.

And this translates into functional benefit where RNA editing shows improvement in the motor skill test compared to the standard of care. Beyond systemic effect, we evaluated the potential of AX-0422 following delivery to the brain. And the preclinical studies demonstrated meaningful restoration of enzymatic activity across multiple brain regions. Our experience shows that the Axiomer EON enables robust and sustained editing in the CNS. These findings support the potential of AX-0422 to address the neurological manifestations of Hurler syndrome.

In summary, AX-0422 is designed to address both the systemic and neurological aspect of Hurler syndrome with a single targeted approach. From a patient perspective, this means potential for additional clinical benefit over the current standard of care. We are developing AX-0422 with a 2-step approach. First, focus on the liver with our lead compound now being in IND-enabling stage, followed by addressing neurological symptoms through intrathecal administration. Cristina will now give you more details about the development plan.

Our initial clinical approach focuses on liver-directed editing, where we have already established nonclinical delivery and pharmacology. This provides a clear and efficient path to generate early clinical data and demonstrate proof of concept in patients. From there, we plan to expand into the central nervous system through intrathecal administration, building on the translational insights generated in the liver and extending our understanding of editing performance across tissues and routes of administration.

Hurler syndrome is a severe multisystem disease, affecting both the liver and the brain. This creates a unique opportunity to bridge liver correction to addressing the neurological symptoms that drive long-term patient outcomes. Our stage approach is designed to derisk development early while building toward a therapy that can address the full burden of disease over time.

It also directly supports our broader CNS strategy, including programs such as Rett syndrome. Overall, this program not only addresses a high unmet need in Hurler syndrome, but also serves as a critical step in expanding Axiomer into CNS indications. Our Hurler program is advancing towards the clinic with CTA-enabling activities ongoing for AX-0422, a CTA filing expected in early 2027 and initial clinical data anticipated in the first half of 2027.

Let's now focus on our Axiomer program, AX-2911, targeting PNPLA3 to address MASH. MASH is a highly prevalent disorder and increasing worldwide. Individuals with the disease have a high unmet medical need due to progression into cirrhosis, hepatocellular carcinoma and liver-related mortality with limited therapeutic options available. PNPLA3 or patatin-like phospholipase domain-containing 3 148 methionine variant is the strongest known genetic risk factor for liver disease progression with approximately half the MASH patients carrying the variant.

PNPLA3 represents a genetic driver of disease that is independent of metabolic factors. That means that even when metabolic pathways are addressed, patients carrying this mutation may continue to progress, highlighting an important unmet need in current treatment approaches. Indeed, patients with this variant may be less responsive to existing therapies such as GLP-1 agonists. From an epidemiology perspective, homozygous carriers of this variant represent approximately 8 million individuals in the U.S. and EU. By editing the methionine to a valine in this variant, AX-2911 is designed to restore wild-type protein function and address the root cause of MASH.

To evaluate AX-2911, we use a humanized PNPLA3 148 methionine model. Unlike standard preclinical models, which rely on diet or chemical injury, this model incorporates primary human hepatocytes carrying the homozygous variant. As such, this model closely reflects human disease progression compared to standard models. And together with an established Western diet, it provides a highly translatable and efficient system to assess therapeutic impact.

We use this model to compare 2 different approaches. PNPLA3 knockdown using ASO previously evaluated in clinical studies and correction of the mutation with AX-2911. Approximately 90% of PNPLA3 messenger RNA knockdown with ASO led to a 36% reduction in lipid droplets. In contrast, 23% RNA editing of PNPLA3 with AX-2911 led to approximately 80% reduction in lipid droplets. Lipid droplets accumulation reflects excess liver fat, a key driver of disease progression in MASH.

Taken together, these results show that correcting the underlying genetic variant can drive a stronger functional outcome than simply reducing PNPLA3 148 methionine expression. This supports the potential of AX-2911 in addressing the unmet medical need in MASH.

As Gerard highlighted, this program is supported by a strong human genetic and preclinical evidence linking PNPLA3 to MASH disease biology, providing a highly validated target. From a development perspective, we declared a development candidate earlier this year and are planning to advance this program through an investigator-initiated trial in China. This approach allow us to efficiently generate early clinical data, leveraging local clinical expertise, access to well-characterized patient populations and a streamlined development environment. The study is designed to assess safety, pharmacokinetics and exploratory biomarkers related to liver fat and disease activity. This approach enable us to generate a clear early read on clinical potential while maintaining capital discipline and flexibility on next steps.

Thanks, Cristina. I'll close by briefly summarizing our expanded pipeline of Axiomer-based RNA editing programs and the key milestones ahead. As you've heard today, our lead program, AX-0810 targeting NTCP for cholestatic diseases is on track to read out target engagement data in healthy volunteers later this quarter, followed by initiation of a patient cohort later this year.

At the same time, we are advancing additional clinical catalysts within our cash runway. For AX-0811, our next-generation NTCP program, we expect to file the CTA this year with initial clinical data in healthy volunteers before year-end. For AX-0422, targeting IDUA for Hurler syndrome, CTA-enabling activities are ongoing. We expect to file the CTA in early 2027 and read out initial clinical data in the first half of 2027.

And for AX-2911, targeting PNPLA3 for MASH, we are actively planning an investigator-initiated trial in China. In addition to our programs, we will continue to advance our Axiomer platform, including AI-driven discovery and high-throughput screening capabilities, as Gerard highlighted. Taken together, this reflects a pipeline that is progressing across both liver and CNS indications, supported by the breadth of our Axiomer platform.

In addition, through our partnership with the Rett Syndrome Research Trust, we are working on AX-2402, our RNA editing approach for MECP2, aligned with our broader CNS strategy. And we continue to progress our collaboration with Eli Lilly, which is focused on advancing multiple RNA editing targets enabled by the Axiomer platform and supports the scalability of our approach.

Financially, we continue to be funded into mid-2027, consistent with prior guidance while delivering existing and new clinical data catalysts across the pipeline in this period. With that, we'll open the call for questions with our covering analysts.

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

I have a couple of questions actually, if that's okay. First, I just wanted to ask about the strategy of focusing 0810 in biliary atresia as opposed to PSC, given that's where, obviously, the initial patient data will be generated. And if that means that 0811 may be is earmarked for PSC? Or are you thinking about development away from PSC altogether?

Steve, thank you for the question. I'm going to ask Cristina to address this for you.

Cristina, you may be on mute [Operator Instructions].

Okay. With that in mind, I will address the question for you, Steve. So we've gone through a rigorous indication selection process to select our primary indication. We are not moving away from PSC, but we are prioritizing biliary atresia as we see that is the strongest combination of the unmet medical needs, the biological clarity and development feasibility.

As you know, BA is a very severe pediatric disease with no approved therapies, and the mechanism is very clean. Bile acid toxicity is the key driver in that disease. And patients are diagnosed early. They're treated in specialized centers and the disease course is well characterized. So that supports efficient and rapid trial development.

At the same time, PSC, we are also very excited about, but we decide to stage that subsequently to biliary atresia.

Okay, Daniel. Second question, and then I just have one quick one after. On Rett, it's interesting. I think you mentioned that you wanted to get some clinical translational data in CNS first and leverage that for the Rett program. But that program is also largely funded, I think, by the external grant with RSRT. So just curious about the decision to sort of step back from Rett and slow that program down. And is it just a function of the Hurler program being closer to the clinic or something else?

Yes, that's a great question, Steve. And yes, so of course, the Rett program is really important to us. We're pursuing that in a partnership with Rett Syndrome Research Trust who are co-funding the work here with 50% in the program.

The RET program would directly go into CNS. And I think the IDUA program that is novel to our pipeline and now recently added gives us the opportunity to really bridge in a staged way.

We can leverage the dual tissue biology that allows us to take one molecule into the liver first and subsequently bridge into CNS, which is a very elegant way to, in a stepwise and derisked way go into CNS. And that will be very informative as we translate RET. So we think on the base of that, we could take the RET program in a much more validated and derisked way into trials.

Great. And then just lastly, with the return of that program, the Hurler program from Lilly, just curious if you could comment on the current status of that collaboration, if they're working on one or multiple other programs preclinically that they retained following this pipeline review that ultimately sent the Hurler program back to ProQR.

Yes, absolutely. So obviously, in the Lilly collaboration, we have many different targets that we're pursuing. This program is a program that, as a result of their prioritization review was decided to come back to ProQR. And we're actually very pleased with it. I think it's a program that fits very well with our pipeline. It's a program that we know well. And it's one that is mid-IND-enabling stage, so allows us to rapidly progress into clinical trials. This also on the Lilly side frees up a lot of resource to really allocate to other programs that are more strategically aligned with their portfolio. So the Lilly collaboration is going forward without any change in priority, and we're really excited about the progress that's being made there.

Our next question comes from Joe Thomas at Oppenheimer.

This is Joe on for Kostas. Maybe just a quick clarification about the bar for success in the upcoming readout with bile acid increase. Is the 2x referring to versus baseline or versus placebo? Just looking for some clarification because in the NHP data, we saw an increase in placebo as well. I was wondering if you're expecting to see the same in the human data.

Joe, thank you for that question, and thank you for dialing into our call today. So the bar for success is multifold. So we're going to look at 3 different measures. We're going to look at the total bile acid, which is a holistic view of the bile acid accumulation in the periphery and in the serum.

Then we will look at bile acid profile, which looks specifically at the conjugated bile acids versus the unconjugated bile acids, and we are specifically interested in the conjugated bile acids as those are the ones that are regulated through NTCP. And then as a third endpoint, we're going to look at TUDCA challenge. TUDCA is a chemical form of bile acid that is orally administered and that is regulated through NCP, and we can completely isolate TUDCA from the other bile acids as it's separate. To answer your question, the twofold threshold we have set for the total bile acid, and we're going to look at it both compared to baseline as well as compared to placebo. And then for the other measures, we're going to look at the qualitative change towards an increase in conjugated bile acid.

Okay. And maybe just a quick follow-up, if I may. Just thinking about the choice to proceed with biliary atresia and PSC data coming at the end of the year, what would the read-through be do you think in PSC patients to potential efficacy in BA?

Yes, that's a great question. So the patient cohorts will indeed be conducted in PSC patients because this is an adult population. So while biliary atresia is the key indication, we plan to pursue AX-0810 for both PSC and biliary atresia. The PSC cohorts will allow us to understand the translation from healthy volunteers to the disease context.

And we think that will be very valuable information to help us bridge towards the biliary atresia Phase II, which is going to be a pediatric study. So we think the totality of the data will help us inform dose, dose frequency and expected effect size.

Congrats on all the progress.

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

Great to see all the updates. Just one quick clarification on 0810 first. All 3 of those cohorts, they all unblind at the same time, right? So you haven't actually seen any of the unblinded data internally. That's right?

Yes, correct. Thank you for the question. So the study is a double-blind, placebo-controlled study, and the study remains blinded.

Perfect. All right. So then for 0810 in biliary atresia, when are you planning to start dosing patients relative to their Kasai procedure? Like are you planning to do more of a focus on long-term outcomes like Ipsen is doing with Bylvay? Or could there be some type of accelerated path here by looking at bilirubin maybe earlier on?

Yes. So obviously, this is to be discussed with the regulators. But the plan is that we indeed pursue an accelerated development path where we look at liver biomarkers and liver health, liver stiffness. And those will help us towards an accelerated approval with a long-term follow-up as a post-market commitment. We expect to treat different stages of the disease post Kasai procedure, but it's still to be designed what exactly we will do in the Phase II. So you will have to stay tuned for that.

Sounds great. And just one last quick question on the Hurler commercial opportunity. I guess how big of an issue are ADAs or discontinuations for any reason for Aldurazyme today? How much efficacy do they kind of leave on the table, especially on the CNS side? Really just trying to understand how much 0422 could expand this market further.

Yes. Thanks for the question. So the CNS part of Hurler syndrome is largely untreated. The Aldurazyme enzyme replacement therapy does not cross the blood-brain barrier. So it does not treat the CNS element of the disease. We think AX-0422 has the opportunity to treat both the liver and the CNS. Currently, patients take a weekly IV administration of the enzyme replacement therapy, which is obviously fairly burdensome and takes quite a bit of time.

In addition to that, our preclinical data, the animal model data suggests that there is additional efficacy to be gained with AX-0422 when we compare this head-to-head in the disease model. So we think that the therapeutic proposition for patients with Hurler syndrome is very significant, both for CNS as well as for the liver.

Our next question comes from Catherine Novack at JonesTrading.

Just curious about for the Hurler syndrome program, how frequently would 0422 be delivered intrathecally? What's the expected half-life for subcu versus IT delivery?

Catherine, thank you for the question. So our molecules delivered IT for CNS are generally very stable and AX-0422 is no exception to that. If anything, it is a bit more durable than other molecules that we work with. So we anticipate that this is probably once every 9- to 12-month administration IT for the CNS element.

Got it. And the subcu element for -- what's the anticipated dosing regimen in that?

So the liver residence time of any oligonucleotide, and this molecule is no outlier there is shorter than for IT. So we expect to dose once every 3 to 6 months subcutaneously for the liver treatment. And that compares to the current standard of care that is weekly dosed through intravitreal administration.

Got it. And then are you thinking about your enrolling PSC patients in the Phase Ib. Is there anything you would see in patients that might impact your decision to prioritize biliary atresia?

Could you repeat the question? I didn't completely get it, Catherine.

When you -- you're still enrolling -- plan to enroll PSC patients into the Phase Ib. Is that correct? And is there anything that you would see that would impact your decision to prioritize biliary atresia as the target for 0810?

Yes. I think that's a good question. I don't think there's anything that would change our plan for the Phase II. We think the plan for the Phase II is set to have the lead indication in BA. But I do want to stress that we're not moving away from PSC. PSC remains a very important indication for us to target. It's just a matter of staging.

Our next question comes from Suzanne van Voorthuizen at Kempen.

On BA, I appreciate the trial design is yet to be determined, but could you elaborate on how 0810 could be positioned in the current care and management of patients? And then I also have a clarification on 0810 and 0811. How do you foresee the development of these programs beyond the Phase I? Should we expect that to choose the next-gen over first? Or is there a reason to believe these programs can coexist in different indications or settings?

Yes. Thank you, Suzanne, for the questions. So I'll take the second question first. We think that AX-0810 and AX-0811 can each stand on their own legs. AX-0810 is our lead program and represents the fastest path to clinical proof of concept and potentially fastest path to market where AX-0811 reflects our continued platform optimization and is part of our broader NCP strategy.

Importantly, for both of them, we are in parallel generating clinical data, and that will accelerate our learning and maximize opportunity around the targets, and we are committed to bringing the best medicine to patients. We think that through this approach, we will learn a lot. And ultimately, with this, we are following a quite successful business strategy that was pursued by companies like Alnylam, who pursued multiple targets, multiple programs for TTR in the clinic and actually to approval and what Vertex did in cystic fibrosis. So you can compare it to what they've done. For your first question, I'm going to see if Cristina is back online. Cristina?

Yes. I'm here. Absolutely. Can you hear me well? My apologies.

Yes, we can hear you all clear.

Okay. Fantastic. So basically, what we're trying to achieve here is a staggered approach. First, we really want to validate the platform, meaning that we can target NTCP; second, to move from healthy volunteers to patients and to patients when we're thinking about the [ tox ] program in adults, PSC as this is a driver mechanism for all cholestatic diseases.

PSC, it was the right indication to try in the Phase Ib cohort. And after based on very established regulatory requirements, we can extrapolate for different populations. And this is why we have decided to go to Phase II with biliary atresia because as we mentioned, there was the unmet medical need, biological rationale and the clear developability. Saying that, as Daniel nicely say, PSC is still in the bank, and this will be part actually of the life cycle management. In terms of 0810 and 0811, I think that Daniel repeat this very nicely. We will really optimize the best molecule to the patient population, trying to establish an NTCP franchise that could serve all the population.

Got it. And maybe one additional question on 2911 on MASH. Can you remind us how the hypothesis you test with correcting PNPLA3, how that differs from the previously tested ASO? You highlighted a stronger effect on liver droplets, but is it a matter of potency? Or is there more to it? And maybe if you can also give some color on the rationale to go for an IIT in China, that would also be helpful.

Thanks for the question, Suzanne. Gerard will address your first question on the mechanism.

Thanks for the question. The rationale behind the technologies is such as follows. Where we see the knockdown approach giving rise to a limited, let's say, decrease in steatosis, we see that by limited editing, by creating a functional protein, we see a massive decrease in steatosis up to 80%. We feel that by correcting the protein to a wild-type like protein is the major differentiator there. So you need a little bit of a function of the protein for it to be most active.

Cristina will address your second question on the IIT.

Actually, this is a beautiful question. So thank you for asking. There are different pathways to actually to derisk programs. One pathway is definitely to go to the standard IND or CTA submission. Another pathway is to go to investigator initiated trials. In investigator initiated trials, there are a possibility to have exploratory hypothesis with a much more focused IND or CTA profile while keeping flexibility in terms of capital, derisking and learning for IND-enabling activities.

This is why we have decided to go with 0911 for an IIT in China. You have seen that this potential mechanism cannot address MASH in general, but actually can optimize link-MASH and non-link MASH for those therapies that are not so responsive to treatment. So using the local regulations in China, we are really hoping that we are really going to deliver a clinical meaningful outcome to derisk the program and optimize our clinical development plan, meaning we will optimize pharmacology, PK, PD, biomarkers that will translate and the population to follow to maximize the effect and to get as soon as possible to the patients that deserve this treatment.

Our next question comes from Ryan Deschner at Raymond James.

Thanks for the question. We've already mentioned this and I missed it, but has 0811 shown higher preclinical editing levels versus 0810? And then I have a follow-up question on 0422.

Ryan, yes, thanks for the question. So AX-0811 showed about a threefold higher editing in the animal model that we use. So it showed about 60% editing in the humanized mice.

Got it. And then for 0422, the 2 different delivery administrations, what differences are there between the actual drug format going into the liver versus what's going into the intrathecal version? And what PD metrics will we be targeting for each administration on this?

Yes. Thanks for the question, Ryan. I'm going to have Gerard address this question for you.

Yes. Thanks. That's a great question. I think the interesting idea is we see a staged path towards the clinic where we are starting with liver and then to expand intrathecal dosing into CNS. We are actually testing a GalNAc molecule taking forward into the liver as we would do typically.

And we are now testing also different molecules to go into the CNS. So we are testing both the GalNAc molecule as the naked oligo to be tested in the CNS as well. What we do see is that we see restoration of the IDUA enzyme activity across the relevant brain regions. And we also see reductions or activation of the enzyme activity across the brain. So that reflects the target engagement in a disease model as well.

And if I may add to continue with the clinical development plan, this is what is so fantastic about this program that, as Daniel mentioned, we have a single molecule that could not only address the peripheral symptoms, but also the CNS symptoms. And for those that are following the pathway, presently not in Hurler, but in Hunter, FDA was willing to have a conditional approval using a biomarker and actually, this particular biomarker were using us in terms of intrathecal administration.

So at the end of the day, we will have a single clinical development path where we're going to be targeting peripheral and CNS looking at the gaps in the peripheral compartment in the central compartment, supported by clinical data in the periphery, most likely post editor capacity and 6-minute walk test.

And in the CNS, it has already optimized depending on the age of the patient with neurocognitive assessment we will be looking at because we're talking about a progressive neurodegenerative with early neurodevelopmental symptoms. It's a complicated disease, but with Axiomer, it can target both peripheral and CNS and this is why we are so excited about that.

Our next question comes from Catherine Okoukoni at Citizens JMP.

This is Catherine on for John. I just had kind of a quick question about biliary atresia. I think you mentioned that potentially even partial improvements in bile flow could have an impact. Can you just expand on that? And if you have kind of a clinical target in biliary atresia that you would want to see in patients that would be clinically meaningful? And what might be potential -- like is there any precedent for what might be meaningful as far as reductions go?

Catherine, thank you for that question. I'm going to have Cristina address this for you.

Yes. This is a very smart question. So thank you for asking. In biliary atresia, what we like about the disease is that we have a single cause, a single etiology.

So basically you have an abstract in terms of the release of bile acids, bile acids accumulate in the liver and therefore, it cause the disease. After surgery and after the Kasai procedure, you start to release the liver. When the bile acids accumulate, the [indiscernible] bilateral of the hepatocytes try to get rid of the bile acids is not sufficient. Why? Because the NTCP is still working, meaning that we are pumping bile acids from the periphery into the hepatocytes.

By blocking the NTCP, we're doing is we're really helping the liver to release the toxic bile acids in the hepatocytes. So one could ask, are we going really to get rid of entire cholestatic disease markers, for example, bilirubin normalization, et cetera. We don't know yet, but we are going to measure those. But what is most important is that the toxic driver of the disease, we're going to be cutting by decreasing the uptake from the NTCP and helping the bilateral receptors get pumped out of the toxic bile acids.

We are going to try different agents in the disease, and we're going to see how we can optimize and maximize the benefit for the entire disease spectrum.

Our next question comes from Keay Nakae at Chardan. You might be on mute.

Sorry about that. A question for Gerard. The 3x improvement in 0811, can you talk about a little more detail how you're able to achieve that? Is it substitutions in the sequence? Is it the length of the sequence?

Yes. Thanks for the question. I think the -- this translation of the knowledge that we've gained over 12 years gets together now on the AI. And we are looking at indeed variations of length, chemical modifications and the stability of the molecule.

So we won't disclose any specifics on the improvements. However, the optimizations, you can look into that area. But we now start to understand way better how to optimize these molecules through our HTS AI.

That optimization you're getting with 0811 in the liver, are they applicable to engaging ADAR in other tissue types?

Yes, yes. So we are expanding that to different liver programs as well as in the CNS, and we're seeing very impressive improvements across the board. So the system is learning. We are feeding the data back into the AI. And across the board, we see very nice improvements. So yes.

So our final question comes from Ananda Ghosh at H.C. Wainwright.

So I have one structural related question with respect to the biliary atresia program. So if you look at the definition of biliary atresia, the issue is actually the absence of bile drainage or the entire drainage system. So I was wondering how does blocking the NTCP channel kind of fit into the mechanistic aspect of disease modification? And then I have one follow-up question on this and one for the Hurler syndrome.

Ananda, thank you for that question. So yes, you're completely correct. Physiological defect in patients with biliary atresia is blockage of the bile duct or absence drug. The cells have a mechanism to get rid of excess bile acid through alternative channels like MRP3, MRP4 and others who can pump bile acids into the blood through the basolateral side of the cell.

What happens, though, is that through NTCP, those same cells are taking those bile acids back up into the cell. So it's a circular pump. And what we do is we break that cycle by reducing the uptake through NTCP. And therefore, a normal balance can evolve inside the liver cells.

Got it. Then I had 2 questions on the upcoming data readout. If you can remind me how are you defining measuring NTCP editing efficiency in the HV setting? And if you have thought about like the NTCP turnover kinetics as you were thinking about designing the trial?

Yes. Thank you for the question. Gerard, would you like to address this question?

Yes. So sorry. So we don't measure editing in the trial. In the trial, we cannot measure editing because the editing takes place inside the liver. And in healthy volunteers, we cannot take biopsies. So therefore, we will not be able to measure editing directly. What we can measure though is the biomarkers that will allow us to correlate it back to the preclinical data, which will allow us to establish an approximate editing efficiency. Could you remind me of your second question?

Yes, regarding the turnover NTCP.

Yes. Correct. Correct. And for the NTCP, we are really looking at the natural history in terms of the disease, cholestatic diseases to see NTCP expression. And the good news is that in biliary atresia, NTCP is alpha regulated and actually can correlate with bile acids and long-term outcomes.

So we are confident that we have sufficient expression of the target that we can maximize the efficacy meaning because this target keeps contributing to the disease by inhibiting NTCP that is upregulated biliary atresia, we can actually block this uptake of the toxic bile acids that drives inflammation, fibrosis and ultimately to transplantation.

And I don't know if you remember, but it's up to 80% of children that despite the Kasai procedures need to go to liver transplantation. So definitely, we believe that this can be a transformative mechanism.

Got it. Maybe a last question on the Hurler syndrome program. How much of wild-type restoration do you think can be disease modifying? And what kind of editing efficiency can that equate to?

Yes. Thanks, for the question. Gerard, do you want to address the Hurler editing efficiency?

Yes. That's a great question. I think the idea is that the editing levels that we are seeing in the Hurler models are sufficient to overcome nonsense mediated decay, restoring a more stable IDUA messenger RNA and enabling enzyme production because IDUA functions through a catalytic turnover, even modest increases of enzyme levels drive a disproportionate large reduction in the substrate GAGs.

We believe the level of restoration is really meaningful because the literature shows that restoration of approximately 1% to 15% of normal IDUA enzymatic function can already improve disease phenotype. So what we see is that restoration of 21% drives to close to normalization of urinary GAG levels. So yes, we do see a field that is really very meaningful.

And in addition, jus to -- sorry, in addition to support Gerard's comments, when you think about the different phenotypes and percentage of IDUA enzymatic activity, when you think about the 3 spectra, the ones that have close to 1%, they don't have a phenotype.

As soon as we go to 8.5%, 3.1, then it's life threatening disease. So if this data that we're showing translates into humans, we are really thinking about revolutionary transformation, not only in the periphery but also in the CNS.

So actually, beyond preclinical data that Gerard just mentioned, when you look at the clinical data and the deficiency in the [ enzyme ] this tell us that we are well above the threshold to show clinical meaningful results.

So this concludes today's Q&A session and the overall event. We thank everyone for joining today. You may now disconnect. All right. If you're still on, we're no longer live. Great job, guys.

Yes. Thank you, everyone. Great job. Yes.

Thanks guys. Congrats.

Yes, you guys can -- I know you guys are going to have your internal...

Good afternoon, everybody. Welcome to the Citizens Life Science Conference Day 2. My name is Jon Wolleben, Senior analyst here. Pleased to have ProQR Therapeutics, a name we've covered for quite some time in many iterations, but I think this is the most interesting version of the company we have today, and we have Chief Financial Officer, Dennis Hom, here joining us. So Dennis, thanks for coming down and talking to us.

Thanks, John. I appreciate the invite and for Citizens for setting all this up for us.

And then with ProQR, tell us what are you guys working on? Like what's the strategy and goal with ProQR Therapeutics?

Sure. So the company has evolved over time, as you alluded to. But since 2022, we've been exclusively focused on developing our Axiomer technology, which is our version of RNA editing. So the strategy we're taking is fairly straightforward. We're developing our own, wholly-owned pipeline of programs based on Axiomer and we continue to innovate on that technology. I would mention that we are the pioneers of RNA editing. So ADAR-mediated RNA editing, we started looking into in 2014, really before anyone even thought this was possible. So it's all homegrown. We don't rely on any external IP, and we probably have the broadest IP estate of any RNA editing company.

And you came on board a little over 1 year ago. Talk to us about what drew you to ProQR and then also how that first year has been compared to your expectations?

Sure. what drew me really was the potential of the science. So I'm probably not like most CFOs you'll meet. I'm very much driven by what's fun and interesting in science to me. My education was in biology, but I've been in and around biotech and pharma for my entire career.

And so when I looked at ProQR first, initially, I thought RNA, wow, when I used to work at RNA in a lab, you could not get that stuff to stick around long enough to do anything with it. But over the last couple of decades, RNA therapeutics has really blown up, and in particular, when we talk about RNA editing, the potential of it is really amazing. It's essentially DNA-based editing without the downside. So you don't have -- maybe it's too much of a blanket statement to make. There's always downside to any therapeutic, right? But think of the potential as you can create proteins with modified function of your choosing without permanent genetic modifications.

And is that -- the DNA editing, we're getting there, and we're making progress, but obviously, a lot of overhanging concerns. And so the benefit of RNA editing is the potential reversibility, the lack of that overhang safety risk primarily?

Right, exactly.

Do you miss anything from an editing capability, editing RNA versus DNA or application?

Sure. Of course. When you think about what makes sense for gene therapy or base editing of DNA, it's this one-and-done hope. But as it turns out, as we study that more and more, one-and-done really isn't one and done. There's a waning of durability of gene therapy over time. There are the challenges of not being able to re-dose because most of gene therapy and those other approaches require all the machinery to do the edit to be delivered alongside the gene that you're trying to replace.

So yes, the downside of RNA editing is that it's transient, but that's also its upside. But keep in mind, what we're using to attract the enzyme to do the edit, is purely an oligo. So what we're delivering to the body is just an oligonucleotide, about 30 bases of RNA. And the kinetics, the safety of that has been well studied in other uses of RNA therapeutics.

And when you say transient, what are you guys thinking as far as the target durability and dosing administration schedule?

Yes. In our initial indication or initial program targeting cholestatic disease, we're thinking 3 months, is the target. For CNS indications where we believe the oligo will stick around a little bit longer, 6 to 9 months. So that's -- those are the things we're aiming for.

And the tricky part also with these technologies, RNA editing, oligos is delivery. So talk a little bit about kind of a lot of advance in the past 10 years in delivery of oligos. How are you guys getting your medicines to where you need them to be?

Yes, that's a great question. We have purposely chosen target organs where the delivery is well known and established. So for example, in our lead program for cholestatic disease that targets the liver. So GalNAc delivery or GalNAc conjugation of oligonucleotides has been demonstrated by multiple companies now in marketed products. So that sort of eliminates that risk. In the CNS, for example, we are looking at intrathecal administration of a naked oligonucleotide. So again, a proven method of administration for getting drugs into the brain.

And you mentioned your lead program, AX-0810 in the clinic now. So that's a big step forward fundamentally. Tell us a little bit about that program and asset?

Yes, absolutely. That is a huge milestone for us and the field of RNA editing. We are the second one to get into the clinic behind Wave with their AATD program, but we think that once -- I feel sort of like we're on the cusp of showing Wall Street, the real potential of this technology once you have more than one indication, more than one gene target.

So the lead program goes after a transporter in the liver called NTCP. And what's unique about our approach here versus a mutation correction approach that companies pursuing AATD are going after, we're looking at modulating protein function. That's the real power of this technology. We're taking the transporter and blocking its ability to uptake bile acids from the blood into the liver, but we're allowing the transport of other molecules like thyroid hormones, vitamin D. And so we're hoping that, that preserves sort of the regular function of those other molecules, but blocks the sort of bad function that we're trying to stop here, which is excess accumulation of bile acids in the liver.

And you guys put out some early data in January. What have you guys shown so far and talked about?

Yes. So the early January data was really the -- a little bit of a check the box. But keep in mind, this is a Phase I safety program. So that check the box is important for the first time our technology has gone into the clinic. It was the first few participants in the Phase I, cohort 1. And so the PK was as expected as we modeled and no safety signals so far.

And it is healthy volunteers. So talk us through what we're going to learn in Phase I. Obviously, with the newer modality, safety is super important, but what else can we glean from this first initial study?

Yes. Great question. Unlike many Phase Is, where you're really just testing safety, in this case, we can learn a lot more because of the modification we're making to NTCP. So when you modify NTCP the way we're attempting to do, you're going to keep the bile acids in the blood. So that's what we're going to look at. We're going to see, does this mechanism work as expected and therefore, should work as expected in patients. But in healthies, what we're looking for are 3 biomarkers of target engagement. The first one is a fairly blunt one. We're just looking at total bile acids. So if you block the uptake into the liver, the bile acids will stay behind in the blood, so you should see elevated levels.

And to be specific, we're looking for a sort of a threshold of 2x increase in bile acid levels, and that's based on a lot of things. There is, one, a cholestatic animal model that has shown, when you achieve a 2x increase in bile acid levels, you should see improvements in liver health. There's also clinical proof of this mechanism with another company's drug that is a peptide sort of nonspecifically blocking the NTCP transporter. And that's approved in Hepatitis D. And so in that case, you see patients with Hepatitis D, though, who do not respond virologically, so in other words, the virus is still there with the insult. But in those patients, you're seeing an increase in level of bile acid in the blood. So you're seeing that the block is working and you're seeing liver health improvement. So a 2x increase in bile acid levels is translating to liver health improvement in those patients.

And we've tried to do this before is thinking about you guys are -- your mechanism...

Sorry, I should mention, besides total bile acid, we're also looking at the portion of conjugated versus unconjugated. So that's also important because we're drilling down on NTCP itself. So NTCP is specific for conjugated bile acids. So you should also see the portion of conjugated bile acids increase in blood. The third thing, which is probably the most important is a TUDCA challenge. So essentially, it's a tracer study. So it's as specific as you can get for the action of NTCP. So TUDCA is a synthetic bile acid that we're administering to these healthy volunteers, and we'll see how much of it stays in the blood versus gets moved into the liver. So that's an important one.

How do we think about RNA editing efficiency and what's needed? Like preclinically, we're trying to line up all the different data points we've seen. And you guys have shown some interesting preclinical data, but not like 100% editing. Do we need 100% editing? And then if we hit these metrics that you're talking about in humans, does it -- the drug is working, right? And how much confidence do you have?

So I think there's been a lot of focus on editing percentages. While it's a good measure or when you don't have human clinical readouts. Ultimately, human clinical readouts are the more important functional measures, right? So are you doing what you think, what you need to be doing in a human and disease.

So to answer your question directly, I don't think 100% is required for any of these programs across companies. I know a lot that we've been asked often, do you think there's a theoretical ceiling? And indeed, there isn't because in our hands, not for every target, but there are targets where we've looked at where we've seen up to 80%, 90% editing.

And sorry, I should also mention endogenously, so normally, without drugs or anything, the human uses this enzyme to edit 100% of certain transcripts. So the efficiency is possible to get to 100%, right? You just have to design the right oligo, which is not -- I don't want to make it sound like it's easy to just come up with an oligo that can do 100% efficiency. It's not easy, right?

But I just wanted to like level set so people understand the background. But I completely agree that once you have clinical data in patients, that kind of fixes everything or answers a lot of questions.

Right. So you don't need 100%.

And when are we getting the further data from the Phase I?

So we have told The Street that we'll be announcing data from all 3 healthy cohorts, in the first half of this year. So there's only a few more months left, but yes.

And you said 3 cohorts, have you guys talked about dosing, like levels that you're doing? Do you expect to see a dose response? How important is that in the readout to get more confidence?

So we do have 3 dose levels, 3 mg per kg, 6 and 9. We would hope to see a dose response. So that's what we're expecting.

And then so we have data coming soon. If we hit the targets, what's next?

So if if we hit the targets and the 3, PD readouts are concordant, which we would hope they would be, we would move next into a patient cohort under the same protocol as the healthy volunteers. So that's 4 weeks of treatment period. So we would expect to translate some of the mechanistic data that we see in the healthies to potentially disease biomarkers. But I would caution that in these patients, 4 weeks of treatment is very, very short.

Sure. And when we say cholestatic disease, a lot of options there. Like what makes sense, what may not make sense for an application?

So we've specifically narrowed down on those cholestatic diseases where there are no available treatments. And for us, that currently means we're looking at PSC and BA. PSC being Primary Sclerosing Cholangitis, and BA being Biliary Atresia. We have not announced which one we'll go with. We'll do that alongside the release of the the Phase I data in healthies. So that data will help inform that.

Got it. So we'll get the data. We'll get an idea of therapeutic area and then what -- then we can start level setting expectations for the subsequent data readout and proof of concept?

That's right.

Got it. single center study, correct?

Correct. Single center in the Netherlands.

And then you're just adding on the cohort. So it should be a really streamlined path to moving forward?

That's right.

Got it. And I think this might be a good time as we're talking about therapeutic areas, the development strategy you guys are taking. The other players in the space are going after the same disease that has options out there, which gives investors the ability to benchmark and see how things are going. But as far as the actual application and use, brings in a lot of questions where you're going after more fresh powder. So obviously, part of the strategy big picture-wise, but walk us through how you guys think about prioritization and where you guys are going ahead?

Yes. When we thought about what are the targets that make sense, we have a very strong target hunting group, we call them, and it factors in things like where RNA editing has an advantage over other modalities or existing therapies. And generally, we try to pick therapeutic areas where there is no current treatment.

So PSC and BA are a good example of that, but not always. So our second program in Rett Syndrome, there is an available therapy, but it is primarily focused on symptoms. So our strategy is generally to pick indications where we can showcase the sort of advantage of RNA editing.

And 0810 is in the clinic now, but you mentioned you have subsequent candidates in the pipeline in Rett Syndrome. You have a MASH candidate moving forward as well. Tell us about the earlier candidates and where those are?

Sure. So Rett syndrome, we announced in January that we selected a clinical candidate. So we're going to be going into IND-enabling studies. And the first in-human for that will start in the first half of 2027. The third program that we've talked about is targeting PNPLA3 for fatty liver disease, and that will go -- we actually have not announced our specific development plan for that. We expect to have more on that later this year.

And then with those targets and those conditions, can you talk about, you mentioned RET where there's something available that you think you could have an advantage. What are the advantages that you're going to be going for from a target product profile?

Sure. Well, clearly, with what's available right now commercially, this -- our approach is, a correction of the mutation. So the mutation here is in a gene called MECP2. And so there are clear advantages to addressing the underlying problem, which is the mutated protein, than to what's available now. I think maybe the more apt comparison is with the 2 programs that are gene therapy programs that are in development. And so here, you have to think a little bit about the cause of the disease, which is the mutation in MECP2.

When there are mutations, of course, that's a bit analogous to an under-expression of the gene. But the flip side, there's also a problem. So with over-expression of MECP2, you have something called Duplication Syndrome, which have very similar symptoms to Rett Syndrome. And in levels as low as 1.5x expression, you can already see symptoms. And when you get to 3x over-expression of MECP2, that can be lethal. So when you think about gene therapy and how that's delivered, tight control of expression will be critical.

In addition, well, so I should contrast that with an RNA editing approach like us. An RNA editing approach relies on the existing mRNA. So there's no need to regulate expression because we are not touching what exists endogenously or what's already there. So there's no over-expression or under-expression danger. In terms of durability, of course, the gene therapy approaches are hoping to be one-and-done. But as we're finding out the sort of the durability of these one-and-done approaches are not really one and done, right? The effect can wane over time as the cells turn over. But also you have to think about distribution. Is the gene therapy getting to the various areas of the CNS and the brain? That are needed to help with the disease.

And with 0810 in the lead, how should we think about read-through on the platform, the technology to subsequent programs? Is it one of these where there's enough overlap that we have success here, we feel better about everything moving forward? Or are these more bespoke applications and targets that require their own vetting more thoroughly?

Yes. I'd love to say it's -- the easy answer would be, yes, of course, it's...

This works, that will work...

Yes, every program will be exactly the same. But as we're finding out, indeed, each target has its unique challenges in designing an oligonucleotide that can edit effectively. But having said that, the chemistries we use and the modifications we make to the oligonucleotides are repeatable from target to target. So one program going into the clinic and being successful and shown to be safe, absolutely has a read-through effect on the other programs based on our specific Axiomer technology.

And we mentioned your MASH program targeting PNPLA3. Obviously, investors are very keen on seeing that space evolve because Madrigal's launch has done so well. But you guys are going to be going after a subset of patients. So what's the thesis on going after a subset, when people can go after a drug that targets the more broader, bigger population?

That's a great question. So PNPLA3 is the strongest genetic driver of NASH. So whilst programs like thyroid beta agonist, can address the whole population at a very high upstream level. So it's addressing the metabolic drivers of NASH, those individuals who have -- who are carrier for PNPLA3 may not be served as well from a broad focused medication like a THR-beta. Same goes for GLP-1, same goes for FGF21.

What PNPLA3, you have to think a little bit about what it does. And PNPLA3 is involved in the breakdown of lipid droplets in the liver as well as breakdown of triglycerides, for example. So you can imagine that even when you're treating the upstream effects, the liver is still having trouble breaking down those lipid droplets. I should also mention one thing that these metabolic approaches do not address is also lean MASH. So lean MASH accounts for 10% to 20% of the MASH population. And PNPLA3 is at an even higher prevalence. So carriers in certain populations are seen to have -- account for 70% to 80% of the lean MASH population. So it has very high prevalence in lean MASH.

It is a really interesting genetic subtype and target when you're in the weeds and things. And I think once people realize that, they'll start being even more compelled by that program. But when you talk about cholestatic disease, I guess, MASH could fit in that bucket. Rett syndrome, something different. When you're in charge of capital allocation decisions, how do you think about -- we're at the early innings of really cool science and figuring out where these could go. But then at some point, we're going to have to start funding development programs and potential commercialization. So how do you think about what can stay, what can go with a partnership or how you choose and prioritize these things?

I suppose that really aligns with our company strategy, which is to focus on a wholly-owned pipeline, continue to innovate on our technology. We really view ourselves as sort of -- if you think about other areas of RNA therapeutics, there have been similar companies that have sort of built first, second, third generations of that modality. And that's what we really aspire to be. And then the third leg of that stool is partnerships.

So I didn't mention, but we have quite a massive partnership with Lilly across 10 targets. So we received $125 million upfront from them. It's a total partnership worth about $4 billion. Of course, those are bio-bucks, but between non-dilutive funding from partnerships, and moving our wholly-owned pipeline forward, that's kind of how we focus our resources.

And maybe in the last minute or so, can you remind us to that point, your cash position and what kind of runway that gives you?

Sure. We have about, I want to say $109 million at the end of September, and that takes us through mid-2027. So in terms of milestones on the clinical side, there are three key milestones that will get us through. I mentioned the target engagement readout of the healthy volunteers, that's this half of the year. The last half of the year is initiating the patient cohort of the 810 trial, Phase I trial. Then the third is the initiation of the first-in-human trial for the Rett syndrome program. In terms of other things to look for, as our Lilly program -- Lilly programs, plural, progress, we'll continue to recognize additional milestones. So you should look out for that. And then also, we'll give an update on PNPLA3 and the path forward for that program.

So a lot going on. So we'll keep an ear to the ground. We've got an update coming soon and then giving us more guidance on target indications will allow us to better capture the potential value down the road. So you guys got a lot going on.

Dennis, thanks so much for coming and telling us more about the story today.

Yes. Thanks for having me.

Welcome, everyone, for today's first session. This would be with ProQR Therapeutics. We're joined by the CEO here, Daniel. Welcome. Maybe to start off, can you just give us a quick overview of where things have been? What were you able to accomplish this year?

Absolutely. Thank you for having us today. I do want to say that there's risk associated with an investment in ProQR and our statements around that can be found on the website of ProQR. ProQR is a biopharmaceutical company. We're based in the Netherlands and Europe. Our shares are traded on NASDAQ in New York. And we're focused on the development of RNA editing medicines.

RNA editing is an innovative technology that allows us to treat genetic and common disease by modifying the human messenger RNA. And with that, creates a template to make proteins that enhance health. We can do that by introducing variants that create de novo proteins that have a beneficial effect on the health of people or by targeting mutations that we can restore back to a normal wild-type sequence. This technology we invented at the ProQR Labs about 10 years ago, and we control all the foundational IP around the technology.

And over the years following, we've optimized the technology to a point that in 2021, we entered into a collaboration with Eli Lilly. That is a $4 billion partnership in which we received $125 million in upfront payments. And in that collaboration, we are partnering on up to 15 different targets where ProQR does all the discovery work and Lilly takes it into development and commercialization. We can make up to $250 million in milestone payments for each target, and we will receive royalties on the approved product.

That partnership is proceeding -- progressing really well. There's a lot of scientific progress being made. And hopefully, soon, there will be more to say about development progress from that collaboration. In parallel to that, we are pursuing this technology for a wholly owned pipeline, where we focus on the use of this technology in liver and CNS indications. We have a pipeline of both rare and more common indications that we are developing in liver and CNS.

The lead program in our pipeline is called AX-810 for cholestatic diseases. And this program, we have an open CTA for and are starting a clinical study right now. For this program, we expect to have first human clinical data, PD data in the first half of next year. So that is something we're very much looking forward to. In addition to that, we have a whole range of other programs in our pipeline for cardiovascular disease, for other liver disease.

We have a program for Rett syndrome, which is a neurodevelopmental disease. So a wide variety of applications and significant opportunity to advance our pipeline towards the future.

Okay. Perfect. Maybe before starting with the lead program here that you've announced the trial design for, can you just let us know how did you go about prioritizing PSCBA first? Why not something else like AATD, et cetera? And then we'll take it from there.

Yes, absolutely. So the target universe for ADAR editing is very significant. We can apply this technology across hundreds of different targets and potentially generate a deep pipeline of medicines based on this approach. We see there is a number of different ways to utilize the technology. So for correction of mutations, which you would do in the context of AATD or to introduce de novo variants that actually have a health benefit.

Given this is a platform technology, we set out to generate a robust initial human translational data set. And for that reason, we picked a target where we can measure target engagement in healthy volunteers. We picked NTCP, which is the main contributor to bile acid concentration in the liver. And that is the underlying causality of cholestatic diseases like PSC and biliary atresia. And between those diseases, there's a very high unmet medical need.

There's no approved therapies and both of these diseases are life-threatening. So we think that with this approach, we can both generate a significant data set that validates the technology, helps us to understand the translatability of the science from the lab to the clinic and at the same time, develop a medicine for a really high unmet medical need.

Okay. Perfect. Can you -- okay. So let's start with the PSC and BA program. So you recently announced the trial design. Can you just give us a quick overview of how many cohorts, what doses are you testing? And when can we start expecting some of the results from the trial?

Yes. So the AX-810 program, which we are developing for NTCP, which is a protein that is responsible for the uptake of bile acid from the blood into the liver is being pursued for cholestatic diseases, which do include PSC and BA. The initial trial that we're doing is a trial in healthy volunteers as we can actually measure target engagement in healthy volunteers.

So we don't need to include patients. And that gives us a lot of advantages because the recruitment of a trial with healthy volunteers is quicker and easier. There's less background noise in the data, and it allows us to proper sample size the study to get to a robust outcome. The trial is set up to look at bile acid concentration because we're modulating the transport of bile acid and because of that, the bile acid in serum, so in the blood will increase, and that's something we can measure.

We will also look at the bile acid ratio between conjugated and unconjugated bile acids. And we will do a specific challenge with synthetic bile acid, that's called the [ TUDCA ] challenge in which we can isolate the function of NTCP specifically and measure that post treatment with oligonucleotide. The trial is set up in Europe, where we're based in the Netherlands, where we will conduct a study close to home.

It will enroll 33 subjects across 3 cohorts, 11 in each cohort, which is a randomized, placebo-controlled and double-blinded. So we will treat with 4 doses over the period of 5 weeks. And after we will follow the subjects for another 12 weeks. The study is now about to start. We'll be dosing a patient, first subject in the coming few days. And then we expect an initial look at the safety and the PK data around the end of this year. And all the PD data, so all the target engagement data and the biomarkers will come in the first half of next year.

Okay. Perfect. So one of the things, concerns or rather challenges in liver disease, especially PSCBA is the time line for showing benefit. What is -- is there a path for accelerated approval here? What would that look like? What are you going to measure to see that?

And as a continuation to that question, are you measuring liver stiffness or any other biomarkers like circulating C4, et cetera, for this one, so that could kind of give you a leg up or a head start?

Yes, that's a really good question. So the current Phase I study is set up in healthy volunteers. On the back of the healthy volunteer study, we will do a Phase Ib, which is one cohort of PSC subjects that we plan to dose in the second half of next year and then have results before the end of next year. This will be a 1-month treatment period, similar to the healthy volunteer part of the study.

And that is likely not sufficient to measure a change in the clinical outcomes like liver stiffness. But we will obviously be looking at all the biomarkers and clinical measures that we can, and that includes indeed liver imaging, combined with certain biomarker measurements that we think combined could provide a path to an accelerated approval.

It depends also a bit on the indication because we have not selected yet if we will lead with PSC or BA in the Phase II, and each of them will have a different registration path. But given the high unmet medical needs and the absence of disease-modifying therapeutics for both indications, we think that with a novel therapeutic strategy like targeting NTCP here, there is a potential to develop that in an accelerated manner.

Okay. Got it. And what is the priority in development for BA? How are you going to prioritize that?

So we're currently working through indication selection with key opinion leaders to define if our first study, first inpatient Phase II development study is going to be in BA or PSC. And the factors we're weighing there are developability from a feasibility perspective in recruitment. I think there's the biological rationale for the 2 indications that is slightly different.

And obviously, PSC moves a bit slower. It's largely an adult population. And BA is a much more aggressive disease, which is mostly affecting a pediatric population. So they're -- both have a very different proposition and there's pros and cons to both. But in parallel to conducting our Phase I in healthy volunteers, we will also make a decision on indication selection, and we'll announce that in conjunction with the results of the Phase I.

Okay. Perfect. And on the safety side, can you just give us a quick recap of why pruritus won't be an issue? And how should investors have confidence that that's not going to be a continuing issue with the program?

Yes, absolutely. So pruritus is itch, significant itch that is caused by inflammation in the liver. Inflammation markers signal and lead to itch across the body. This is called pruritus and is a significant symptom of the disease in patients. It's often considered that high levels of bile acid and serum leads to pruritus. We believe that's not the case. We think it's coinciding.

High levels of bile acid and serum coincides with inflammation, but the inflammation drives the itch, not the bile acid itself. And there's 2 important data points to support that. First of all, the mutation that we are creating with ADAR editing is rooted in human genetics. So there is a natural population that lives with the variant that we're creating.

And these are healthy people, healthy people that live with really high bile acid levels in their blood up to 40, 40x higher than a wild-type individual. And these people do not suffer from pruritus. They do not have itch. So although they have 40x higher bile acid, they don't have itch. That's one. The second data point...

Sorry, and there's no variability among patients there. It's all patients with that mutation don't have the pruritus?

So these are healthy individuals. They don't have any disease manifestation whatsoever. The only clinical phenotype they represent -- they present with is high bile acid concentration. The second data point is a clinical trial that Gilead did with Bulevirtide, which is a peptide for hepatitis D that targets NTCP as well. As a result of their study, they concluded that they significantly increased the bile acid concentration in blood, and that was not associated with pruritus in that study. So I think between that, there is a high conviction that this approach will not lead to pruritus.

Okay. Got it. And in terms of outcomes from the healthy volunteer study, just can you just set the stage for what to expect? How are you defining what success looks like? And then as a continuation to that, what is a good percentage of editing that you'd like to achieve? And how is that going to translate into outcomes? Yes.

So we believe on the basis of publications in the field but also work we've done ourselves that if you increase the bile acid level in serum by twofold, you will stop the progression of the disease. So that is the, let's say, the hurdle we've set. We want to increase the bile acids in serum by at least twofold or more. We would like to see that paired up with a shift in the ratio of conjugated versus unconjugated bile acids in favor of the conjugated bile acids.

And then we would like to see the change in the clearance rate after [ TUDCA ] challenge. If we are able to establish that those 3 biomarkers move, and we crossed the twofold increase in bile acid and serum, we believe we have a developable product that will hold the progression of cholestasis. In addition to that, we're also looking for safety and a dose regimen that is acceptable. We dose frequently because it's a Phase I, but the TPP for this program is that we would like to dose once every quarter. And generally, with oligonucleotides that is achievable with the PK of these molecules.

Got it. And is the percent of editing directly correlated to the change in the serum bile acid?

Yes. Good question. So we've published data at ASGTC that shows that there is a relatively linear correlation between editing and bile acid concentration in the serum. And we see that with 5% editing, you get a twofold increase in bile acid. With 10% editing, you get a fourfold increase in bile acid in blood. So that's relatively linear. And in this study, we will not be able to measure editing because we cannot take a liver biopsy. But we will be able to correlate it back to the nonclinical data.

Okay. Is there such a thing as too much editing being bad or?

We don't think so. Certainly not for this target, but probably in general for the use case of RNA editing.

Okay. Perfect. And then once you have the data from the healthy volunteer trial, what does the time line look like to starting the next phase of trials? Would it be a pivotal trial? Or can you just lay the path for that?

Yes, potentially, although we can't commit to that yet. It depends on the data and the indication selection. So we are working through those plans right now. We are looking at accelerated development plans to get the drug would it prove to be efficacious, approved as quick as possible. But the plans for that, we will unveil once we have the clinical data in hand.

Okay. Perfect. Anything else you want to highlight on the program? Or should we move on to the Rett program?

Let's move on to the next program.

Okay. Got it. So to start off with, what is the level of priority for Rett?

So Rett is a very high unmet medical need. It's affecting people that are born with normal cognitive function, but then develop this neurodevelopmental disease due to the absence of the MECP2 protein. We can, for certain genetic variants, reverse that by restoring normal function of the protein through RNA editing and with that potentially take away the underlying defect of the disease that would allow for people to gain normal developmental function even later in life.

So it's not a neurodegenerative disease. It's a neurodevelopmental disease. So animal data suggests that if you reintroduce the protein later on in life, normal function can be restored. This program is really important. We developed this in a partnership with the Rett Syndrome Research Trust that is cofinancing the development thereof. And if all goes to plan, we will select a clinical candidate in the very short term and then rapidly advance that into clinical studies.

Okay. Got it. And do you have a DC for this yet or?

We have not announced a clinical data.

Okay. Got it. Okay. Perfect. Quickly, how do you -- how does this program differentiate from gene therapy? What is the value proposition there?

Yes. I think it's great for the Rett field that there's so much activity. We learn a lot collectively. Hopefully, there's therapeutics that will reach these patients because it's such a severe disease. Rett syndrome is a very unique indication because you cannot overexpress the MECP2 protein. If you overexpress it, you actually get into what's called duplication syndrome.

So it needs to be very tightly regulated. And I think value proposition of RNA editing here is that you restore the present messenger RNA and with that can never overexpress the MECP2 protein. So that gives a lot of comfort that you stay within the range of where the protein needs to be expressed. We can target this on a mutation-by-mutation basis. So the most severe form of Rett is caused by stop codon mutations.

And there's 4 of those stop codon mutations that each have about 5,000 patients that we can target with individual editing oligonucleotides. So we're bringing the first one into the clinic. And then if that succeeds, I think there's a strong case to go into the other stop codons as well.

Okay. Perfect. A lot more to discuss. We have run out of time. So let's leave it there. Thank you so much for coming.

Thank you.

Good morning, and welcome to the ProQR Therapeutics Virtual Investor and Analyst Event. [Operator Instructions] As a reminder, this webinar 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.

Good day, everyone, and thank you for joining us. I'm Sarah Kiely, Vice President of Investor Relations and Corporate Affairs at ProQR. To begin, let's briefly review today's agenda and introduce our speakers, which you'll find on Slide 2. First, Daniel de Boer, our Founder and CEO, will provide a brief strategic overview of the business. Following that, Dr. Cristina Lopez Lopez, our Chief Medical Officer, will welcome Professor Henkjan Verkade from the Beatrix Children's Hospital and University Medical Center of Groningen.

He will share insights into unmet medical needs, disease pathophysiology and key biomarkers for assessing NTCP modulation in cholestatic diseases. Then Cristina will provide an in-depth review of the design of our Phase I trial of AX-0810 in healthy volunteers to assess safety, tolerability and PK of this first editing oligonucleotide to enter the clinic from our Axiomer platform and expectations for biomarkers and proof-of-target engagement.

Finally, Dennis Hom, our Chief Financial Officer, will provide a corporate outlook update. We're looking forward to sharing these updates with you today. Following the presentations, our management team, Daniel, Cristina, Dennis and Chief Scientific Officer, Gerard Platenburg, will host a Q&A session with covering analysts.

Today's event is being recorded, and both the replay and the presentation slides will be available on our website afterward. Before we get into the program, I ask that you note Slide 3, which includes our forward-looking statement. During the presentations today, we will make forward-looking statements. There are risks and uncertainties associated with an investment in ProQR, which are described in detail in our SEC filings. I will now turn the program over to Daniel de Boer. Daniel?

Thank you, Sarah, and good morning, everyone, and thank you for joining us today. We stand at the threshold of a major milestone for ProQR. With our CTA authorized in Europe, our Phase I trial in healthy volunteers beginning and initial data towards the end of the year, this is the moment where our science begins to translate into the clinic on the path to help patients.

At the core of ProQR is Axiomer, our proprietary RNA editing platform. Axiomer harnesses the body's own editing enzyme, ADAR, and uses short chemically modified oligonucleotides to direct it precisely where we wanted to edit the RNA. Editing an adenosine into an inosine, which is translated as if it was a guanosine. What this means in practice is that we can repair mutations, restore or fine-tune protein function and even modulate protein activities in ways that opens up entirely new therapeutic possibilities.

In short, Axiomer's versatility allows us to fix, fine-tune and reprogram proteins at the RNA level without altering the DNA. That's the power of the platform that we've been incubating for over 10 years. Our strategy with Axiomer is grounded in 2 pillars: our pipeline, where we're advancing multiple proprietary programs, which are rooted in human genetics and our partnerships, most notably our $3.9 billion collaboration with Eli Lilly, which is exclusively focused on Axiomer RNA editing.

Together, these pillars underpin how we create value through our science, our pipeline to bring these new medicines to patients, our partnerships, our team and our financial strength. And today, I want to highlight how all those drivers are converging at this important stage for ProQR.

First, scientific innovation. Our Axiomer platform is built on our proprietary editing oligonucleotide science invented here at ProQR. With a leading IP estate and robust editing efficiency demonstrated in liver and across CNS, Axiomer is poised to enable transformative impact for patients. Second, our pipeline. AX-0810, now with an authorized CTA is starting human trials to generate target engagement data. We're also building a leading capability in RNA editing in CNS and have demonstrated durable and efficient editing across regions of the CNS.

AX-2402, our first wholly owned CNS program, targets the MECP2 protein for Rett syndrome. And beyond Rett, we see CNS as a major area of opportunity where our platform can deliver transformative therapies. Behind these, earlier programs such as AX-1412 for cardiovascular disease and AX-2911 for MASH broaden the scope into larger common diseases.

Third, our partnerships. Our strategic collaborations with Eli Lilly and the Rett Syndrome Research Trust validate the strength of our science and accelerate development with important financial and other resources and expertise. Fourth, our team. We've built deep in-house expertise in RNA science, drug development and clinical execution. This year, we further strengthened the management team with the appointment of Dennis Hom as our Chief Financial Officer; and Dr. Cristina Lopez Lopez as our Chief Medical Officer, positioning us to execute on this next stage of growth.

You'll hear more from both of them today. And finally, our financial strength. We're funded into mid-2027 with a runway to achieve multiple clinical and platform milestones. So how does this translate in what we'll be sharing today? We look at 3 horizons in our pipeline, the near term, where today, we will zoom in on AX-0810, our lead program targeting NTCP for the treatment of cholestatic diseases.

Now that the CTA is approved, we are starting a target engagement first-in-human trial. And today, in this event, we'll walk in detail through the trial design, the endpoints and the expectations for the data. Next, our CNS capability and first pipeline program, AX-2402 for Rett syndrome, advancing rapidly towards candidate selection, uniquely positioning ProQR as a leader in neurological RNA editing medicines.

And beyond, we have several other pipeline programs, including AX-1412 for cardiovascular disease and AX-2911 for MASH, which leverage and advance our platform, strengthening the portfolio and opening the door to previously unaddressable targets. These 3 horizons position ProQR strongly and make clear that we are poised for value creation at every stage. Today, Cristina will walk us through AX-0810 and the trial in more detail. The centralized review process of our CTA submission in Europe took longer than we had expected, reflecting the relative newness of the process and variability in review timelines. Now that the CTA is open, we look forward to walk you through the specifics of the trial in more detail.

For that, I will hand over the call to our Chief Medical Officer, Dr. Cristina Lopez Lopez, to take you through AX-0810, our lead program and the first clinical trial for this program. Cristina?

Thank you, Daniel. I'm excited to present today on our most advanced program, AX-0810, which has just received CTA approval and will now begin its first in-human clinical trial. We're also delighted to be joined by Professor Verkade from Beatrix Children's Hospital of the University Medical Center of Groningen, a world-renowned expert in pediatric liver disease, who will share insights into NTCP and the biomarkers selected for this trial.

Before we dive into the details of the trial, I would like to briefly remind you of our strategic rationale for targeting NTCP in cholestatic diseases and why we are so enthusiastic about this compound. We believe AX-0810 has the potential to become a first-in-class therapy targeting NTCP by acid reuptake to address one of the core drivers for cholestatic diseases. The fact that we are modulating a protein through RNA editing is a major milestone for the field and a step toward transformational therapies for patients with severe unmet needs.

Let me provide you with some additional details about cholestatic diseases. Cholestatic diseases include a wide range of conditions affecting individuals from childhood to adulthood. They progress from inflammation to fibrosis, leading to chronic liver injury. Despite their diversity, they share a common biological denominator, toxic accumulation of bile acids in the liver that contributes to inflammation, cell damage and fibrosis.

This all converges to create a powerful therapeutic opportunity to target bile acid toxicity as a shared disease mechanism. Bile acids are released in the intestine from the liver and are mainly used by the body to digest fat. Bile acids are costly for the body to produce. To conserve energy, the body relies on an efficient recycling system that transports bile acids from the bloodstream back into the liver.

One of the key factors in this process is called sodium tau correlate co-transporting polypeptide or NTCP. As Daniel mentioned, one of the most striking aspects of our Axiomer platform is its versatility, particularly its potential to enable entirely new therapeutic approaches, including precise protein modulation.

AX-0810 is the first other RNA editing oligonucleotide designed to modulate wild-type protein to enter the clinic. Through a specific A-to-I RNA edit, AX-0810 fine-tunes NTCP protein to limit bile acid reuptake from the bloodstream into the liver, directly reducing the toxic bile acid accumulation inside the hepatocytes that drives cholestatic diseases.

With this novel mechanism, this program is positioned as a disease-modifying therapy with the potential to alleviate symptoms, encourage static diseases and most importantly, prevent or delay disease progression, ultimately reducing health care resource utilization and the risk of fatal outcomes. Our conviction comes from the converging evidence, biological rationale, human genetics and preclinical data all reinforcing AX-0810's potential as a transformative approach.

Let me walk you through the scientific rationale and the supportive evidence. First, a strong biological rationale. As I mentioned, NTCP is the main transporter for bile acid reuptake. Elevated intrahepatic bile acid levels are directly linked to cholestasis, inflammation and fibrosis. Second, NTCP as a target is validated in human genetics. Healthy individuals with NTCP variants have reduced bile acid uptake but no adverse effects, demonstrating both safety and efficacy potential.

Third, we see clear target engagement with Axiomer editing in preclinical models. Axiomer editing reduces bile acid uptake and increases plasma bile acid levels. Fourth, we have functional relevance confirmed both preclinically and clinically. In vitro and in vivo studies show that modulating NTCP decreases bile acid uptake, increases serum bile acids and improves biomarkers of liver health.

Furthermore, clinical proof of concept in hepatitis D demonstrated that NTCP modulation improves liver health. And finally, AX-0810 is highly selective and specific. Our approach precisely modulates the sodium binding pocket of NTCP without affecting expression or membrane localization, demonstrating its potential to modulate the target without significant off-target effects or impacting other functions.

Taken together, this body of evidence builds a robust derisk case for AX-0810 as a first-in-class disease-modifying therapy for cholestatic diseases. Within the broad spectrum of cholestatic diseases, we have the potential to target multiple indications. Among these, 2 stand out for the significant unmet medical need. The first is primary sclerosing cholangitis or PSC, which affects more than 80,000 adults across the U.S. and Europe. The second is congenital biliary atresia or BA, a devastating pediatric disease that impacts approximately 20,000 children worldwide.

Both conditions are severe, progressive, life-threatening and may require liver transplantation, and option associated with significant clinical and economic burden. Importantly, there are no approved disease-modifying therapies available today, highlighting the need for truly transformational treatment options. This is exactly where AX-0810 has the potential to make a profound impact.

And we are very pleased to be joined today by Professor Verkade, one of the world's foremost experts in pediatric liver disease, who will give you more information regarding these cholestatic diseases and the unmet need. His groundbreaking research has shaped the field's understanding of hepatic lipid metabolism, bile acid transport, metabolism and signaling in health and pediatric liver disease. Importantly, his work has direct relevance to the development of NTCP modulating therapies such as AX-0810. It's a true privilege to have Professor Verkade with us today to share his expertise and perspective on NTCP biology and biomarkers in our upcoming first-in-human trial. Professor Verkade, over to you.

Thank you, Cristina. It's my pleasure to illustrate a little bit the findings and the problems of cholestatic liver diseases. It will be a short presentation of which title will be therapeutic targeting of bile acid circulation in cholestatic liver diseases to disclose other interests are that I have a consultancy, advisory board appointments with different companies and have some funded research, both the fees for this are actually paid to the institution.

There is a high unmet medical need in different cholestatic diseases. And one of them is, for example, primary sclerosis cholangitis or PSC. This is a disease that this table shows the main characteristics that's actually occurring both in children and in adults, in children, mostly in the second decade between 10 and 20 years of age starting, but also in adults between 30 and 50 years of age. The disease is so severe because we -- at this very moment, we don't have very effective drugs that prevent the cause of progression of disease and frequently, it goes into the need for transplantation.

Annual transplant rate in children is between 17% to 30% and lifelong, probably closer to 50% as we know now. In adults, it actually is worse in the sense that it even adds up to 1% to 2% per year of the patients, and that's not only everything. The problem is also that after transplant, between 20% and 40% of the patients experience a recurrence of the disease, which may actually necessitate another transplantation or even a third transplant. And certainly has been associated with a shortened expected lifespan of these patients.

Another disease I would like to have your attention to is biliary atresia. Also, biliary atresia has high unmet medical needs, as an example of the cholestatic diseases. Biliary atresia is purely a pediatric disease. It becomes apparent in the first weeks of life, mostly by exaggerated or remaining jaundice and at some point in pale stools. The population incidence is low. Only 1 in the 10,000 to 20,000 birth neonatal jaundice appears. The progression, however, is rapid and without surgical treatment, the survival does not extend the second birth [Technical Difficulty].

In the '60s, there was a surgery development successful, which is called the Kasai procedure. Nevertheless, however, even with the Kasai procedure, about 70% to 80% of these children with biliary atresia do need a liver transplantation before they reach adulthood at age 18. This major cause of disease going to transplantation can actually be also derived from these data on the 16,000 present liver transplantations, which have been performed in Europe since the '70s, divided into 3 -- approx, 3 eras before 2000 to 2009 and the recent area since 2010.

It shows that the blue part of the graph, which is biliary atresia, has been consistently about 40% to 50% of all pediatric transplantations. So biliary atresia is responsible for almost half of the liver transplant at pediatric age. To discuss biliary atresia and PSC or in general cholestatic diseases, it's very helpful and I think understanding that we delineate what is the enterohepatic circulation of bile acids.

This scheme shows the liver and as a central organ in the enterohepatic circulation of bile acids. The liver is the place in which bile acids are synthesized, depicted here by the green balls and are secreted into the bile duct, gallbladder here and to the intestine.

At the end of the small intestine, they are taken up for the majority, 95%, reabsorbed and transported through the portal vein towards the liver to undergo again, cycling a secretion into bowel and thereby filling the cycle, the enterohepatic cycle, enter from the intestines to the hepatic, the liver, and this goes on. This is very efficient and in humans with normal physiology, this cycle takes place about 4 to 6 times per day.

Cholestatic disease is, in general, the process in which the bile acids do not sufficiently get out of the liver into the intestine. This can be by hard block at the bile duct level, but it can be also by genetic diseases or immunological diseases like PSC or biliary atresia that the bile ducts are actually disappearing through a damaging process, a fibrotic process before and after birth.

And this leads to the accumulation of bile acids in the liver where they have toxic effects. And secondarily, the bile acids are also spilling over into the systemic circulation. And that's why cholestatic liver disease is frequently also defined by an increase of bile acids in the systemic circulation measured by elevated serum bile acid levels.

The mechanisms by which bile acids actually damaging are damaging the liver and thereby the whole system is, for example, occurring here through the bile acids generating cell stress and cell death. And you can see it on the left of this graph, either by genetic factors or environmental factors, you get this cholestatic liver disease, you get these immunological processes that may actually be the origin or contribute to the propagation of the disease and actually provide actually damaging patterns into the hepatocytes as well as sometimes in the bile duct.

And the NTCP modulation as a therapeutic strategy that this company now is propagating in their approach is to prevent bile acids to enter the liver where they are mostly toxic. And if the bile acids are not entering the liver, you are expected to reduce the hepatocyte bile acid concentration, the [ intrahepatic ]bile acid concentration and thereby hepatocyte stress and cell death and secondarily, to reduce liver inflammation and fibrosis.

This paper published this year is on the second disease I was creating biliary atresia. Biliary atresia, as I tried to explain, has been greatly helped by the development of Kasai portoenterostomy. However, a major fraction of the patients still need at some point in their pediatric life, childhood life, liver transplantation. And this study published in JHEP this year illustrates that is strongly associated with the amount of total bile acids in serum after Kasai surgery from -- to come back to the problem of enterohepatic circulation, cholestasis, as I explained, is that bile acids are remaining in the liver and are not being excreted as was suggested here into the blood, but largely remain in the liver to prevent to prevent the [ enterohepatic ] circulation, there are several strategies.

One strategy is to prevent, if you have still some bile acid secretion into bile to prevent the reabsorption of bile acids. The reabsorption of bile acids is an effective way to drain the enterohepatic circulation and thereby, the amount of bile acids that needs to be secreted into bile is actually decreasing because the liver new synthesis of bile acids cannot compensate for the complete loss of bile acids by the tools.

So this way will actually decrease the amount of bile acids that need to be secreted into bile. Accordingly, the bile acid levels in the spillover of bile acids into the systemic circulation usually decrease as well. And this is a good example for the so-called progressive familial intrahepatic cholestatic liver diseases or BSEP deficiency in which there is this IBAT inhibitors, the inhibitors that have recently been approved by EMA and FDA that inhibit the secretion -- the reabsorption of bile acids from the intestine and in some patients, a fraction of the patients actually decrease the symptoms of cholestasis and also the biochemical effects of cholestasis.

The point is that I inhibitors do not work in all conditions. And the major one to consider is you do need at least some bile acids to be secreted from the liver into the intestine because these I inhibitors are not absorbable in the intestine and only prevent the reuptake of secreted bile acids. Therefore, in conditions that bile acids are not or minimally excreted only into the bile, IBAT inhibitors do not work. And that is, for many diseases, the case that the bile production and the biliary secretion of bile acids is severely compromised, which is expected not to be amenable to IBAT inhibition.

Rather, for those conditions, you would prefer to have a prevention of bile acids secretion in the liver where they are, of course, expected to liver to damage. So therefore, this uptake inhibition pathway or strategy to inhibit MTCP bile acid uptake is actually clearly needed perhaps for these diseases to some extent, but certainly also for other diseases.

In the hepatocyte, this is the picture here to the bottom right bottom, and that's boxed with the red line, try to -- the concept tries to prevent bile acids entering the liver by inhibiting NTCP. What is the background of this approach? Because you would maybe guess that an increase in bile acids in the systemic circulation is a bad situation in a bad condition.

I think the whole medical field has thought the same way until this paper appeared in 2005, that was, I think, 2015, 10 years ago, in which there was an NTCP deficiency patient identified actually in the Netherlands. And these patients appear to have an NTCP deficiency without a very clear phenotype. But for example, this child did not have conjugated -- did not have pruritus and also no liver disease to an appreciable amount.

This slide shows, for example, over time, this is a girl with values between 0.8 years of age to 5.3 years of age. And these are the liver, the conventional liver enzymes like transaminases and look at this, they are in a normal range between 30 and 40. Bilirubin, normal between 5 and 14, ALP normal and [ gamma-glutamyl ] normal, although at the expense, quite interestingly, the total serum bile acids, which are normally about up to 15 or 20 were between 400 and actually 1,225.

So extremely high bile acid levels, no pruritus, no clinically significant liver disease. And actually, this child only had a problem with -- problem with too much but at least symptoms of a little bit well absorption of fat-soluble vitamins, which is the function of conjugated bile acids in the intestine, but this could be overcome by secretion.

If you have these high bile acids not in the liver, you still have them, of course, in the plasma, in the systemic circulation. But the good news is that the liver and other organs can take care of it that you can sulfate bile acids that actually can allow their secretion into the urine. So the sulfation or other approach of bile acids that are circulating in the systemic circulation, they make them more hydrophilic, less hydrophobic and actually enhance their disposal from the body. So it's not that these bile acids continue to increase every day and live longer. But in contrast, you get rid of it and partly by excretion via the urine.

One specific NTCP inhibitor, bulevirtide has been approved for hepatitis D, and this illustrates the power of this approach to decrease an activity, not only for the hepatitis D, but also for the secondary effects on the liver physiology. First, as expected, if you do increase -- if you do inhibit NTCP, the bile acid increase. And in this case, this was 3 to 4 -- two to fourfold in plasma over time in 30 weeks up to 50 weeks, 1 year.

Interestingly, dose dependently, this drug in these patients decreased liver stiffness significantly and also improved on the bottom panels, the initially abnormal liver enzymes. Even in patients that did not respond theoretically. So the inhibition of bile acid accumulation and the bile acid uptake by NTCP blockade is suggested to have anti-inflammatory effects on different immune cells and actually confers hepatoprotection in this condition.

And the company has chosen for 3 independent parameters that complement each other to allow an unequivocal conclusion that if they all go in the same direction, indeed decrease NTCP-mediated bile acid uptake. The first, as can be derived already from what I explained just before, if you do decrease NTCP activity and the transplant activity, one can expect that total bile acid levels in plasma do increase. because, as said before, NTCP is the single-entry point for conjugated bile acids and -- which make up the majority of bile acids in serum anyway in the plasma.

So the first parameter is a change and in fact, an increase in plasma total bile levels. Secondly, and that goes to the composition of bile acids, bile acids are in different forms and compositions as species, but the major discrimination is conjugated bile acids versus unconjugated bile acids. NTCP is particularly involved in the process of conjugated bile acid uptake by the hepatocytes.

And accordingly, not only total bile acids will increase if you do decrease NTCP level activity, but particularly the change will be in plasma conjugated bile acid levels as a second parameter to confirm that there is a mediated bile acid uptake decrease.

Finally, and completly independent experiment to further delineate an effect on conjugated bile acid uptake, it has been chosen to go for an administration of a conjugated bile acid, which is quite uncommon in physiology of humans, although it's used therapeutically in other cases, it is a bile acid with a specific name taurine conjugate tauroursodeoxycholic acid or TUDCA or TUDCA.

Since this is very lowly present in the condition of a healthy human, by administration, you can tailor its cause in the system. If you do administer this specific bile acids orally, it will be taken up by the intestine and appear in serum. And since this is a perfect substrate for NTCP, its disappearance from the plasma compartment will be strongly dependent on NTCP activity. And accordingly, if NTCP-mediated uptake is decreased by the therapeutic manipulation and the mRNA impairment, it will be expected that the clearance of UDCA from the plasma compartment will be delayed compared to the condition in which there has been no manipulation.

So by these 3 different mechanisms and parameters, it's possible to assess the effect on the transport activity for total bile acids, the specificity for NTCP of conjugated bile acids and also of a conjugated exogenous bile acids to further prove the point. And this information will on top of this more mechanistic information, also likely inform on dosing regimens for future trials in the disease population.

In summary, I hope to have illustrated to you that there is a high unmet medical need for different cholestatic liver diseases, for example, PSC, which is both an adult and a pediatric disease as well as biliary atresia, purely pediatric liver disease. And unmet medical need extends even to the need for liver transplantation, which is very high in these diseases and particularly for PSC also leads to retransplantation.

The mechanism that these diseases are actually playing out in the body is that there is an inadequate metabolic adaptation to the bile acid overload of hepatocytes. The different -- the disease is different. So we are sure that the other factors play a role as well. But the concept of hepatocyte stress and death that trigger inflammation and fibrosis is a common denominator in these types of diseases.

Since NTCP is the key transporter mediating bile acid uptake from bam into the liver, blocking NTCP decreases is expected to decrease the uptake of bile acids into the hepatocyte and thereby has certainly the potential to reduce hepatic stress and cell death and secondarily then reduce liver inflammation and fibrosis or progression of fibrosis.

This is an interesting assessment of target engagement. It needs first-in-human safety and tolerability, of course. And I'm quite interested to look at the future of the development of this drug.

Thank you very much for your attention, and I would like to give the word back to Cristina.

Thank you, Professor Verkade, for this excellent presentation and your insights into cholestatic disease biology, NTCP targeting and relevant biomarkers. I would now like to give you more details on the design of our first-in-human study, which will assess AX-0810 in healthy volunteers.

We are very pleased that our innovative study design, which does not require a traditional single ascending dose approach has been positively reviewed and supported by regulatory agency in Europe. This design offers several important advantages. It allow us to properly assess pharmacokinetics, safety and tolerability at different dose levels, while also enabling generation of pharmacodynamic data.

Ultimately, this approach is designed to position us to move rapidly and confidently into patients. The study will enroll 33 healthy volunteers with 24 participants receiving active treatment and 9 receiving placebo across 3 dose cohorts. The design includes 4 subcutaneous injections. With the first 2 injections given 15 days apart, we will fully assess the effect of single doses on safety, tolerability and PK. And with the following injections given weekly, we aim to achieve meaningful concentrations in the liver in order to relatively quickly understand the pharmacodynamic readouts.

After the dosing phase, there will be a 12-week safety follow-up period. An independent data monitoring committee will conduct safety reviews before each step of dose escalation. For pharmacodynamic assessment, we plan to investigate biomarkers related to target engagement. This will ensure we capture the most relevant data and signals to guide the next steps of AX-0810 development.

I will provide more details of these biomarkers in the next part of my presentation. We expect initial safety, tolerability and PK data towards the end of the year. And furthermore, we will present the target engagement data in the first half of next year. We are excited about this progress, and we look forward to sharing these important updates with you very soon.

Let's take a closer look at the study objectives, starting with safety and tolerability. Our study design and optimized dose regimen in this first-in-human study enable us to achieve pharmacologically active liver concentrations efficiently. This approach ensures that we can robustly assess the safety and tolerability of AX-0810 for potential long-term use in patients with cholestatic liver disease.

Next, let's look at how we are capturing relevant outcomes to guide future development using a carefully selected panel of biomarkers designed to provide meaningful insights into therapeutic activity. Our PD assessment is designed to capture the full picture of AX-0810's potential in humans. Specifically, we are measuring NTCP engagement via multidimensional assessments. 3 key biomarkers will be assessed, chosen for their ability to provide information about target engagement, selectivity and discriminatory potential among doses for future therapeutic intervention.

Total bile acid levels in plasma to assess the effect on bile acid transporter activity, bile acid profile to measure the ratio between conjugated and unconjugated for specificity and via TUDCA challenge, which mimics the abundance of bile acid in plasma in the disease and will inform dosing regimen.

Additionally, we are collecting samples to further investigate exploratory biomarkers to further elucidate what will happen in the disease compared to healthy volunteers. Zooming in on each of the key biomarkers, let's have a look at total bile acids in plasma. NTCP transporter is responsible for more than 90% of total bile acid reuptake from the bloodstream back to the liver.

By modulating NTCP function with AX-0810, we then expect to see an increase in plasma total bile acids as they cannot enter in the liver anymore. A twofold change in plasma total bile acids as presented by Professor Verkade will be considered clinically meaningful in cholestatic patients. And our preclinical studies confirm that Axiomer treatment can lead to more than twofold increases in plasma bile acid levels.

With that foundation, the next step is confirming AX-0810 specificity for NTCP. NTCP is the main transporter responsible for the uptake of bile acids and has a specificity towards conjugated bile acids. As such, a step-wise increase in these specific bile acids in the plasma will further demonstrate that increasing bile acids is driven by AX-0810 specificity for NTCP transporter only. And this data were also confirmed from our preclinical model in mice, where a shift of conjugated versus unconjugated bile acids in the plasma was achieved.

To further strengthen the evidence, we introduced a TUDCA challenge to mimic an overall boost of bile acids in the periphery as would happen in cholestatic diseases. Tau conjugated bile acid or TUDCA, it is produced in very limited quantity in human and exclusively taken up into the liver by NTCP. Thereby, external administration of TUDCA mimics the disease in healthy volunteers, help us to assess in a very targeted and specific manner, NTCP bile acid function.

The TUDCA challenge will also provide a discriminatory effect between doses to inform dose regimen selection. A decrease in plasma clearance as reported by an increase in TUDCA plasma levels is expected to further confirm AX-0810 target engagement. In our preclinical studies, a decrease in TUDCA clearance was observed. To ensure that these readouts are robust, we have also optimized how and when we capture biomarker changes.

We know bile acid levels fluctuate naturally through the day, depending on circadian rhythm and diet. To address this, our first-in-human study has carefully standardized conditions, including optimized time points, meals and controlled diet. This rigorous design gives us confidence that we can distinguish between baseline variability and drug-induced changes compared to placebo.

To summarize, our plan is designed to meet multiple objectives: one, to demonstrate precise target engagement; two, to confirm disease relevance; and three, to provide a detailed mechanistic understanding as well as dose response and durability of the effect. Together, these factors give us conviction in the translational potential of NTCP as a therapeutic approach in cholestatic diseases. When translating these learnings into the disease population, we expect to see a consistent pattern in bile acid biomarkers.

In patients with cholestasis, plasma total bile acids are already elevated. As such, AX-0810 intervention is expected to further increase in plasma. And in addition, we expect an increase in the conjugated versus unconjugated ratio. What is critical is that this change in bile acids will help to release hepatocytes from excessive toxic bile acid levels.

And this is expected to be accompanied with meaningful clinically relevant improvements in patients such as reduction in liver enzymes, decrease in cholestasis markers and decline in fibrosis.

Finally, let's look ahead at the development path and the upcoming milestones. We anticipate announcing safety, tolerability and PK data from Cohort 1 towards the end of the year, followed by target engagement data in the first half of 2026. In parallel, activities to include a patient cohort in this first-in-human following completion of the healthy volunteers part are already underway.

The objective here is to generate early data in a disease setting in a timely manner to support next steps in clinical development. This cohort will proceed following additional regulatory approval. We expect to have some data from this around the end of 2026. We will provide guidance when the cohort is started. We are very excited about the progress of AX-0810 and the milestones ahead. We are confident our first-in-human design will deliver a comprehensive safety, PK and PD profile and position AX-0810 for rapid advancement into patients.

And with that, I will hand it over to Dennis Hom, our Chief Financial Officer, to share more.

Thanks, Cristina. I'd like to wrap up by emphasizing some of the key value drivers that Daniel covered today. I joined ProQR about 6 months ago because I was super excited by the scientific innovation happening here and the broad potential of the Axiomer platform. ProQR invented RNA editing as a therapeutic modality and holds the foundational patents in the field. We have been making good progress with the pipeline. And as you heard today, we're entering the clinic with AX-0810 for cholestatic diseases, the first-in-human study using Axiomer.

Beyond this, we're advancing applications in CNS with AX-2402 for Rett syndrome and in broader indications such as NASH and cardiovascular disease. Together, these pipeline programs illustrate the breadth and scalability of the platform. We have done all of this alongside our strong partnerships with Lilly and the Rett Syndrome Research Trust. These collaborations validate the strength of our science and provide valuable resources and expertise to accelerate Axiomer progress.

From a team perspective, we've strengthened leadership this year with the addition of Dr. Cristina Lopez Lopez as our Chief Medical Officer. She brings deep development and translational expertise, particularly in CNS. I bring a background spanning investment banking, big pharma and biotech across finance and corporate development roles. Finally, we're fortunate to be funded well into mid-2027, having ended June with about EUR 120 million on the balance sheet, providing us runway that funds multiple clinical and platform milestones.

Taken together, these value drivers position ProQR to advance RNA editing medicines for patients and create long-term value for shareholders. Thanks for joining us today, and we look forward to updating you in the months ahead.

We will now open the call for Q&A with our covering analysts.

Our first question comes from Steven Seedhouse at Cantor Fitzgerald .

Actually, I had 3. I'll just ask them one at a time. The first is on the patient cohort that looks like you're planning to add in Phase I. What indication are you planning for there? Or will it be a mix of different cholestatic patients?

Steve, thank you for the question. I'll let Cristina address this question.

Thank you so much, Steve. For our patient cohort that we are planning to initiate after we have the data in healthy volunteers, we are planning to include PSC patients.

Great. And then one of the differences between NTCP and IBAT inhibition, I think, would be the expectation that NTCP inhibition would also reduce de novo bile acid synthesis. Curious if you could comment on that and if there is a circulating biomarker, something like C4 that might allow you to assess that. I didn't see that in the plans. And I'm just curious if there's a reason why not or if there's sort of a weakness in that biomarker in healthy volunteers or something.

As I mentioned before, our key biomarkers for target engagement, selectivity and discriminatory effect are the ones that I described in the presentation, total bile acids, the profile and the TUDCA challenge. However, we are collecting biomarkers for exploratory purposes, samples that will be analyzed at the end of the study. And this indeed includes C4. So we are basically assessing the entire bile acid pathways to elucidate potential feedback loops.

Terrific. Last question, just -- there's some recent data from a, I guess, next-generation NTCP inhibitor. This is Assembly's molecule. It drove a lot of increase in circulating bile acids like several hundred-fold in healthy volunteers at their highest dose. I'm just curious, assuming you saw those data, what you make of those data, does it change your expectations at all for what the dynamic range of circulating bile acids would be and what sort of effect you might be able to drive with an RNA editing oligo.

Thank you. Actually, we are following that to better understand that data, but we still are convinced that our -- the potential of AX-0810 fulfill the unmet medical need -- potential fulfill of the unmet medical need for the indications that we are interested.

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

Really informative event. Let me just follow up on Steve's -- one of Steve's questions. So let's just say that your NHP data translates really well into healthy volunteers. Like let's say you get four or fivefold plasma bile acid increases from baseline or maybe even more. How do you think about which dose you'll take into patients? Like what is the level you believe may result in very strong or kind of near maximal efficacy in patients?

Gavin, thanks for the question, Cristina.

In the current study, we are really trying to explore the entire dynamic range of potential -- based on the preclinical data of the potential editing change in bile acids while also assessing the safety and tolerability profile. We know that from 5% editing onwards, we will start to see changes in bile acids. In principle, we will really try to target and to maximize the editing, but always with an acceptable window in terms of safety and tolerability.

Yes. So to add to that, Gavin, we complete the healthy volunteer cohorts. And on the basis of the readout of those cohorts, we will select the dose that will go into the patient cohorts that will conclude in the second half of next year.

Okay. Great. And then maybe on the safety side, can you just walk through the key elements you're looking to derisk in the Phase I study, I guess, specifically kind of calling out pruritus or any transient liver enzyme elevations or anything else you're looking to not see?

Absolutely. So in terms of the safety assessments of the first in humans, we are doing the standard safety and tolerability assessments. This will include any potential adverse events. We will perform ECG data. We will perform labs. And as part of those labs, for example, we are going to measure, of course, liver enzyme.

Based on the paper presented by Professor Verkade, this increase in bile acids in the periphery did not translate in pruritus. So we don't have evidence that we will have pruritus. However, of course, we are going to be measuring any potential skin or dermatological reactions, including itching as part of our safety data set.

Awesome. I'm just going to squeeze in one last one. What's the relative focus we should place on some of the different pharmacodynamic measures? Or really is the key point that the different measures should be concordant?

For the bile acids, the total bile acids, what we are really trying to assess is the type of -- to assess the modulation of AX-0810, blocking the uptake in general of the bile acids and therefore, preventing the uptake into the hepatocytes where they can cause toxicity.

With the second, the conjugated versus the unconjugated, meaning the bile acid profile, what we are assessing is the selectivity of our RNA editing because we know that NTCP blocks primary sorry, by blocking the binding pocket of NPCP, we block specifically the conjugated bile acids. The third biomarker is a challenge so that we are performing in healthy volunteers, a, to mimic the disease because we are giving orally a pool of an external bile acid to increase the bile acids in plasma.

So we expect, if we are very selective to impact the clearance of TUDCA because it will not go inside the hepatocyte. Additionally, TUDCA will give us additional discriminatory effect to distinguish between doses because sometimes when we look at total bile acids, we could have different variability. As I mentioned in my presentation, to minimize the variability, we have really standardized the conditions when we give the meals as well we take samples at the same time of the day to minimize impact of card variability.

Our next question comes from Jon Wolleben at Citizens.

A couple for me. You guys have given us preclinical data before for some first-generation oligos. And now that we have the in-human dosing, hoping you could talk a little bit about what you saw preclinically at this dose range to give you confidence you're in the right range there? And if you expect this 3-milligram per kilogram dose to be therapeutic? Or is this just kind of the first low dose, and we'll have to wait to see more from the higher doses?

Thanks for the question. So preclinically, we've seen the proof of target engagement in several species. We've been looking into humanized mouse model to understand the impact on bile acids while editing. We have been using NHP data to basically inform us about safety dosing regimen and liver concentration. And basically, the combination of those data helped us to get excited to move forward into the clinic. So basically, the combination of the data helped us to determine target engagement markers and to move forward. So that's the basis of our current moving forward.

And Jon, you asked a question about if the 3-milligram level would potentially lead to PD biomarker changes. We think that could be the case, but we're going to review all the 3 cohorts together. And on the basis, there of draw conclusions on the response and the potential dose response curve.

Yes. Just on that point, Daniel, so the data around year-end is just going to be safety, PK, tolerability, and then you'll be giving us the target engagement from that first cohort with every -- with all 3 cohorts later in 2026.

Correct. Our next question comes from Ryan Deschner at Raymond James.

Thanks for the question. How broadly do you think an NTCP targeted therapy like 10 could be applied to cholestatic diseases? And do you think the therapy like this could be effective in diseases where IBAT inhibitors are currently used? And do you have any feel for why bulevirtide is not being used or developed in BA and PSC?

Ryan, thank you for the question. So we think that the NTCP therapeutic approach is a novel and very differentiated approach from anything else that is out there and has been tested before. NTCP is a target that directly sits on the liver.

And because of that, we think it may have a much more direct effect on the disease of cholestatic diseases, which is largely driven by the accumulation of bile acids in the hepatocytes that leads to inflammation to fibrosis and ultimately liver failure.

We believe that with this approach, we could target a wide variety of different cholestatic diseases, including PSC and BA, which are the ones that we are currently predominantly focused on. But there is a potential to expand into other indications as well. You asked why bulevirtide, the peptide by Gilead for hepatitis D has not been tested in cholestatic diseases. We can't comment to that. It's not our molecule. So we don't know why that has never been tested.

Got it. And maybe one more quick one. Do you anticipate looking at liver stiffness or pruritus at all in Phase I?

At the moment, we don't have finalized the protocol for the addition of the patient cohort. However, based on the treatment duration because the study will mimic in terms of the doses because we want to replicate the biomarker signature that we see in healthy volunteers. For the duration of the study, we will not anticipate to see changes in biomarkers, for example, FibroScan.

However, we can definitely as soon as the protocol develops together with regulators, we could potentially add specific measurement as exploratory endpoints. But I should mention that the main objective for this patient cohort is to replicate the biomarker signature and to determine that we are actually engaging the target in patients with cholestatic diseases.

Our next question comes from Andreas Argyrides at Oppenheimer.

Also for this very informative presentation. Two from us. Can you provide additional color on kind of ongoing discussions with regulators around the use of these biomarkers to support potential accelerated approval? And then what factors would go into the decision to advance AX-0810 in biliary atresia?

Thank you, Andreas. Cristina, go ahead.

Yes. So I will split my answers in the 2 buckets. I mean, first, about the biomarkers and the clinical significance of those biomarkers and to address about the potential accelerated approval. So in terms of the meaning of those biomarkers, these biomarkers were selected specifically to address the objectives of the first-in-human trial, not to assess clinical efficacy as it will happen in subsequent trials.

These biomarkers we discussed with regulators and was part of our interactions in the CTA. They basically just approved and they approved the scientific validity, and there was no questioning about the use of these biomarkers also in terms of the decision-making. When we are talking about the population moving forward for Phase II onwards. We are still having both indications and our investigation. We believe that both BA and PSC, both there are 2 indications that have a very high unmet medical need.

And based on the scientific rationale and the tractability of the hypothesis, we believe that we could develop both clinical development plans. After we get the results for the first in human for the Phase I, we will provide additional guidance about what will be our indication of interest. When we are talking about potential biomarkers to be used as surrogate end points or potential for accelerated approval, we have planned additional health authority interactions when we present the data from our first-in-human trial.

Our next question comes from Keay Nakae at Chardan.

Two questions. First, in terms of the dosing interval, does your preclinical data suggest that, that could be stretched out at all beyond what you're evaluating here?

Keay, thank you for the question. Cristina?

Yes. So the dosing interval, so with the dosing interval that we are implementing in the first-in-human trial, basically on one side, we use this dosing interval based on what we have learned preclinical. And we have 2 main objectives with this particular dosing interval.

The first one is after the first injection, we don't provide the second injection after 15 days. And the reason is we would like to fully assess the safety and tolerability and potential PD after a single dose administration. The subsequent injections, what we are really trying to do is to get sufficient exposure into the liver as fast as possible in order to understand the safety and in order to get pharmacodynamic readouts of therapeutic potential. You also mentioned about the stretch the dose regimen. Can you please further elaborate what did you mean?

Yes. Can the dosing interval as you enter into patients be longer?

The dosing interval that we are using in our first-in-human trial do not reflect the dose regimen that we are going to implement subsequently. It was only to achieve our objectives in a timely manner to get into the patients as quick as possible.

Yes. okay. We -- our TPP says that we want to dose every few months. Just for the purpose of the first-in-human study, we're dosing weekly to load up as much drug in this 4-week window as we can.

Great. So I appreciate that. And then in terms of the plasma bile acid biomarker, while you mentioned that a 2x increase would be clinically meaningful in patients, at least at your starting dose, how much of an increase in the healthy volunteers would you hope to see?

Yes. So we believe that a twofold increase in bile acid is indeed where the disease changes. So that's what we see as a minimum for the first-in-human study. As we indicated before, we're testing several doses to hopefully establish a dose response curve with levels that are increasing the total bile acids beyond that.

And in addition to that, we will better understand the dynamics of the bile acids, as Cristina alluded to in her presentation, using the different measures of both conjugated bile acids as well as looking at the TUDCA challenge.

Our next question comes from Catherine Novack at JonesTrading.

I have a question about the TUDCA challenge in NHPs. Can you tell us whether this was AX-0810 or a different Axiomer? And was this delivered with GalNAc or LNP?

So thanks for the question. That was done previously, and that was with another research tool molecule that we tested for the TUDCA challenge. However, the pharmacodynamic effect of that was completely the same. So it showed editing of the target to actually show the target engagement and thereby also the reduced clearance of TUDCA. So it was like that.

And was it GalNAc?

No. I think the initial studies, if you may recall, we tested different formulations to get the drug into the NHP. And these particular experiments were done with LNPs. Subsequently, we went over to GalNAc molecules for the subsequent development of the molecule for AX-0810, sorry.

Okay. And then for the EON Axiomer, you also used LNP to deliver, I think, up to 4 mg per kg dose. How do we think about translating this LNP data from EON-A into GalNAc in humans? You've given us data comparing Axiomer AX-0810, but I'm not sure how to look -- how to think about the LNP dose versus the GalNAc.

Yes. I think the general way that we view is that LNP provided us with a very useful tool to get tissue exposure of the drug, but the subsequent development of GalNAc liver targeting or hepatocyte targeting extrapolating from the LNP data provides us with the basis for the next, let's say, development. And I think GalNAc in our hands is preferable for development further into the clinical setting.

And what was the reason for weight-based dosing versus fixed dosing of the oligo in humans?

This is a good question. And in this first in human, we really wanted to minimize variability and to really adjust exposure very precisely to the healthy volunteers to really optimize the study design and to get robust conclusions.

[Operator Instructions] So our next question comes from Ananda Ghosh at H.C. Wainwright.

I have 3 questions. The first one would be, is there any idea of what's the turnover rate of NTCP and how does it correlate with the editing efficiency and also with respect to the durability of the ADAR? That will be the first question.

Yes. Thank you for the question. Gerard, do you want to address this?

I think the turnover rate of the protein itself is relatively short. I can't give you a day rate or something like that, but it's relatively fast. I think that is also the reason why the bulevirtide needs to be dosed on a daily basis. And could you?

Yes. Maybe to add to that, the durability of the effect is not driven by the stability of the protein. It's driven by the stability of the EONs that subsequently lead to the edit. And we believe the EONs are catalytic, so they can edit multiple target messenger RNAs. So the durability of the effect is driven by the stability of the molecules.

Great. Maybe from the safety perspective, the elevated bile acids, particularly hydrophobic bile acids are considered to be toxic. Is there a protocol to measure hydrophobic index in your -- the HV trial?

Well, what we really like about this target is that we're essentially mimicking what human genetics has already established. So there is a wild-type healthy population -- sorry, there's a healthy population that's living with this specific variant that do not have any side effects from living with the variant. So the change that we're introducing does not negatively affect individuals, and that's already established. And therefore, we don't expect any side effects of just the change in NTCP function.

And we are measuring the entire profile of bile acids. So in case that we see anything, we can do some subgroup analysis to better understand any potential signal for the hydrophobic bile acids.

Got it. Very helpful. And maybe the last one. The increase in bile acid is also known to be linked with FGFR and FGF19 and FXR expression in intestine. Did you see any change in the preclinical model so far? And does it -- and can those changes act as another validation of the biomarker data, which you plan to see with respect to the bile acid profile?

So thank you for the question. Very interesting. Yes, we do feel that, that's an important market to follow. And as Cristina alluded to, we will be -- as an exploratory market, we'll be monitoring that in a subsequent clinical trial. But for sure, it's an important market to follow, yes. Thank you.

Great. Thank you for the questions. So this concludes today's Q&A session and the event. Thank you, everyone, for joining. You may now disconnect.