Today, I'm John McHutchison, CEO and President of Assembly Bio, and I'd like to welcome you all to our event today. We're excited to introduce another new research program that our Chief Scientific Officer, Bill Delaney, and his team have underway, focused on inhibiting the entry of both hepatitis B and hepatitis delta viruses.
Also, we have with us Professor Michael Manns, who I will introduce in a moment. While hepatitis delta virus may be less well-known in the U.S. healthcare landscape than hepatitis B or C, hepatitis delta infection also remains a significant and serious health problem without adequate treatment in many parts of Europe and Africa, the Middle East Asia, and parts of South America.
Hepatitis delta is referred to as a satellite virus because it can only infect those already infected with hepatitis B or infect individuals at the same time as they acquire hepatitis B infection.
Most recent estimates conservatively suggest that approximately 5% of the nearly 300 million individuals chronically infected with hepatitis B globally are infected with hepatitis delta. In those 12 million people, the added burden of delta infection is known to accelerate disease progression, increase the incidence of liver cirrhosis and liver cancer, and it is thus ultimately associated with higher morbidity and mortality. This, of course, also creates a greater burden on our healthcare systems.
In our mission at Assembly to deliver finite and curative treatments for patients with hepatitis B, we also have with this program an important opportunity to address the urgent need of those individuals concurrently infected with hepatitis delta and B with the aim of improving their quality of life and outcomes.
The three of us on this call today and many others on the Assembly Bio team were involved in the efforts to turn hepatitis C into a curable disease, where it was imperative that we think broadly and creatively about how to suppress and eradicate the virus. The same is true with hepatitis B, where we are exploring multiple ways to effectively and completely shut down viral replication as we are doing with our core inhibitor candidates or to blocking new virus from entering uninfected cells.
This latter approach is the focus of the new research program that you will hear more about today. In fact, we plan to also introduce several additional new programs during 2022 that build upon the strength of our existing pipeline of potent core inhibitor candidates and expand our portfolio with novel approaches for treating viral diseases more broadly, leveraging the exceptional experience our team has in this area.
We are also very fortunate to have with us today Professor Michael Manns, an international expert in liver diseases and viral hepatitis, including hepatitis B and delta. For more than 35 years, Professor Manns has served in clinical and research roles at leading medical and academic institutions, and he is currently president and board member for research and education and at Hannover Medical School in Hannover, Germany.
He's also a founder and chairman of HepNet, an important national network on viral hepatitis and the German Liver Foundation. Over the years, Professor Manns has received numerous awards, including the International Hans Popper Award and the EASL Recognition Award, and he has published more than 1,000 articles in international peer-reviewed journals. We are grateful that he has made the time to join us and share his expertise and overview of delta infection and his views on new potential treatments.
After Professor Manns' overview, Bill Delaney will tell you more about our hepatitis B, hepatitis delta viral entry inhibitor program. He'll cover things including what we are aiming to achieve, where we are with our research activities and what we have seen to date, why we are excited and confident about the program, and what to look from us as this body of work progresses.
Since I joined Assembly in mid-2019, I've made it a priority to assemble what I believe is the dream team for virology R&D. We've worked to move more and more potent core inhibitors into the clinic, but at the same time catalyze novel programs to combat hepatitis B and other viral diseases. Bill has headed those efforts with the outstanding group of scientists he has now assembled in his group here, and I'm pleased that you'll be hearing about this work today and more throughout the year also.
Before I turn this over to Professor Manns, I'll quickly touch on a few housekeeping items regarding today's event. I'd like to remind you that we will be making forward-looking statements. Please refer to our SEC filings for a full list of disclosures.
This webcast will also be available for replay on the Assembly Bio website shortly after the event has concluded. The slide presentation will also be available there for download. Following the prepared remarks today, we'll be hosting a Q&A session. You may submit your questions at any time during the event by entering the text into the Q&A box at the bottom of the video player.
If you experience any technical issues during the broadcast, please first refresh your browser and then if the issue persists, please message the technical support team using the chat box at the bottom right corner of your screen. With that, I'd like to turn the event over to Professor Manns for his remarks. So, Michael.
Yeah. Hello, John, ladies and gentlemen. Welcome and greetings from Hannover, Germany. Hepatitis D, also called hepatitis D virus infection, is the biggest unmet need in hepatology, I would say, at least in viral hepatitis. I would like to introduce you to this very specific virus and explain to you why we need so urgently treatments. Next slide. I want to discuss with you the epidemiology and natural history of the disease, the standard of care we are providing today, and the new treatment concepts for future therapies .
Next. Epidemiology and natural history. This is very interesting. Next slide. You can see that this is a virus which is an RNA virus. It's the smallest of all animal viruses. There are no enzymes, but ribozymes, and the genetic information only encodes for the small hepatitis D antigen.
There is also the small and the large hepatitis delta antigen. The small one increases replication. What is also very important, that this virus needs a co-infection with the hepatitis B virus infection since the hepatitis B virus provides the coat for the hepatitis delta virus. Without this coat, there is no uptake of the virus into the liver cell. Next slide. This is a global prevalence figure showing the hepatitis delta virus infection all over the globe. You see there are some hotspots.
You see Mongolia in red. There are also hotspots in the Amazonian basin in tribal villages. Then you have high prevalences in areas of the Middle East, of eastern countries, and others, as you can see here. Limited information is available for many parts of the world, including Africa.
Since it's a co-infection of hepatitis B and D, we have to look which of the hepatitis B carriers is infected with hepatitis D virus. We estimate from the studies so available so far that at least 12 million chronic hepatitis delta virus carriers are there around the world. Next slide. As I mentioned before, this is a very rapidly progressing disease. It's the biggest unmet need because we are lacking therapies.
What is shown here, it's a very early study by Dr. Fattovich from Italy, that when we look at the progression to liver cirrhosis, that patients with hepatitis delta, HDV/HBV co-infection, have a more rapid course compared to mono infection with hepatitis B alone. Next slide. This is more recent data from Dr. Manesis, and it shows the cumulative incidence of liver events, meaning signs of decompensation of cirrhosis, including cancer.
Again, the hepatitis D co-infection has a higher rate over time of cumulative incidence of liver events compared to hepatitis B mono infection, as you can see here. Next slide. When we look at cancer, it's known that liver cirrhosis is a precancerous state, and that the risk to develop liver cancer on the basis of an underlying cirrhosis is between 2% and 8%.
What you can see here, that if you have a co-infection of hepatitis B and D, there is an increased risk of hepatitis B mono infection, which is very important to underline that a hepatitis D co-infection of B means a more progressive disease. Next slide. Now I want to discuss treatment.
Since this is a co-infection, we need to tackle hepatitis B, but we have learned over years that suppressing hepatitis B is not suppressing the progression of liver disease due to hepatitis delta. Next slide. First of all, before discussing the results of treatment, we have to look at screening procedures. Everybody with hepatitis B, according to the European guidelines, EASL, should be tested for hepatitis D.
First, we test for antibodies, and if the patient has a hepatitis D antibody, then we test for hepatitis D RNA to look whether the replication is evident. EASL is very strict, recommending every HBsAg positive individual should be screened for delta, which I also agree and support. In America, the recommendation is that hepatitis B carrier patients should be tested for delta if they have a risk. Next slide.
This is data from a study that Dr. Wedemeyer from our center and myself published, the so-called HIDIT-1 study. For a long time, we know, in particular based on the studies from Italy, that interferon is improving ALT transaminases liver enzymes and also hepatitis delta RNA. However, this was the largest study of its kind, testing pegylated interferon given once a week, either alone or together with adefovir, at that time a nucleotide analog used to treat hepatitis B.
What you can see that the hepatitis B treatment by adefovir alone had no impact on hepatitis delta RNA. That interferon had a significant decrease in hepatitis delta RNA. However, the addition of the HBV drug, adefovir, had no beneficial effect. Next slide.
When we look at the surface antigen, you see that the combination, you see a decline in hepatitis B surface antigen, not so if you give interferon mono or adefovir alone. Next slide. We then, some years later, did a study with the German HepNet that Dr. McHutchison introduced to you. It's an international study, German centers from Romania, Greece, and Turkey. We compared pegylated interferon alpha-2a alone or the combination with tenofovir.
That time, the widely used hepatitis B drug, also nucleotides. You see between 23% and 30% was after 96 weeks, the outcome result. What it means, HDV RNA negativity. However, these 96 weeks results were not superior to 48 weeks, and tenofovir had no significant beneficial effect. Over the years, we learned that interferon is beneficial, however, only in one out of four patients.
Next slide. When we look on long-term results, this is Dr. Cihan Yurdaydin also from our center, you can see that interferon is associated with an improved clinical outcome in hepatitis delta. Here you see the cumulative event-free survival. These data confirm previous study out of Italy, the country where the hepatitis delta virus was discovered by Dr. Rizzetto. Next slide. Now we discuss new treatments and new treatment concepts. None of them is approved yet, apart from one, which I will discuss. Next slide.
Regulatory and guideline recommendations on efficacy endpoints are as follows. When we discuss treatment, we also have to discuss the endpoint. There is some consensus between the FDA and AASLD and EASL that the treatment goal should be to achieve at least two log reduction of hepatitis delta RNA and also normalization of ALT.
FDA asks for normalization of ALT, while EASL and AASLD mainly ask for log reduction of delta RNA. Next slide. Here is the life cycle of the hepatitis D delta virus. You see, number one, the uptake of the virus via the receptor, and the receptor has been identified some years ago by a Chinese group. It's the bile acid receptor NTCP. After uptake in the liver, you see the processing of the virus, including various steps, including a prenylation.
There are several therapeutic targets. You have bulevirtide, which is inhibiting the uptake at the receptor at one, then you can have interferon, and then you can have RNAi, no approved drug yet. You can have lonafarnib as a prenylation inhibitor, and you have nucleic acid polymers, which are inhibiting the secretion of the virus out of the liver cell.
Next slide. There is bulevirtide, which has conditional approval in the European Union by EMA. The summary of the results with bulevirtide monotherapy are as follows. In 50%-60%, we see an HDV RNA decline of at least two log. At the same time, ALT normalization of 43%-73%. However, this drug does not lead to a decline of hepatitis B surface antigen in the serum, which means this drug will not lead to cure of hepatitis B, but significant improvement in hepatitis delta.
There are side effects, asymptomatic, dose-dependent elevation of bile salts, injection site reactions, and discontinuation of bulevirtide may lead to reactivation of both hepatitis D and hepatitis B, and also exacerbation of hepatitis. Next slide. There is a phase III study ongoing. These are preliminary data presented at last year's EASL meeting, the International Liver Congress, ILC.
We will see the final results at EASL in June this year. You see here you have a placebo arm, and you have two doses of bulevirtide. As you can see on the right side that bulevirtide giving subcutaneously significantly has advantage over placebo, meaning both RNA reduction and ALT normalization. Next slide. There is also a phase II study available looking at the combination of bulevirtide with pegylated interferon, and you see that the combination is superior to the monotherapy.
This is also a view to the future that a combination of bulevirtide and interferon will be beneficial. Next slide. This is a summary now of the drugs that are under clinical development.
Bulevirtide has conditional approval in the European Union, based on phase II and phase III results. We can combine it with interferon, and we could demonstrate both HDV RNA decline and ALT decline and normalization, safety issues, mainly local reaction, increase in bile acids. The replication inhibitor is also in phase III, and it has demonstrated also in phase II HDV RNA and ALT combined with pegylated interferon alpha. Interesting is peg interferon lambda.
Since the receptor for interferon lambda is only expressed in the liver cell, it has efficacy like interferon alpha, but less side effects. Here we have data available on HDV RNA. Other more data will come soon. Less side effects than pegylated interferon alpha. The nucleic acid polymers, so far only phase II results of efficacy on HDV RNA.
Finally, JNJ-3989 is an siRNA approach, phase II, but however, no published data. Next slide. Ladies and gentlemen, I hope I could demonstrate that hepatitis delta is the worst form of viral hepatitis. 12 million chronic HDV carriers may be an underestimation due to incomplete global epidemiology. There's a high prevalence of delta in risk groups like IV drug abusers, dialysis patients, and migrant populations. In Germany, 20, 30 years ago, patients came from the south of Europe, of Greece, of Turkey. Now they come from eastern countries of the former Soviet Union.
Unfortunately, globally, we have no universal hepatitis delta screening of surface antigen carriers. I support the guidelines of European Association for the Study of the Liver that every surface antigen-positive hepatitis B carrier should be tested first for hepatitis delta antibody and, in the case of positivity, of hepatitis delta RNA.
We need efficacious, tolerable, and affordable HDV targeted therapies. Hopefully, I could demonstrate this by the presentation that I did. Next slide. The opportunities we have in delta is that it's the greatest unmet need in viral hepatitis, and we need therapies for hepatitis D. There are several molecular targets that have been identified. There are several molecules at various stages of clinical development. Interferon is a candidate for combination therapy, and curing HBV would also cure HDV.
So far, although there are many drugs in development, in clinical development for the treatment of hepatitis B in order to cure hepatitis B, the development of cure for B is still early. This is another argument that we need urgently specific drugs to interfere with the life cycle of the hepatitis D virus to prevent progression. Next slide.
Thanks to Markus Cornberg, working with me in the field and helping me to prepare this. Finally, I want to thank you for your attention. Next slide. This is the cartoon of the virus again. Please remember, it's the more smallest of all animal viruses we know. It's based on an RNA encoding for the delta antigen, but you need co-infection with HBV providing the surface, otherwise the virus would not be taken up to the liver. Thank you very much again.
Thank you, Professor Manns. Your comments, Michael, and summary of the disease due to delta, the current therapies and what's new that's going on in the area and what the unmet needs are fantastically and importantly and extremely relevant. You've summarized it beautifully for us. As you said today, you said to me in the past as well, it really is one of the most important liver diseases that the field and the liver practitioners and academics are working on. We feel it's very important as well.
Next, I'd like to hand things over to Bill to provide that overview of Assembly Bio's viral entry inhibitor program. Bill has been with us approximately two years.
When we first sat down and talked about Bill coming to the company and what he would like to work on, delta virus was one of the first things he actually said to me. I'm glad we're now at that stage now where Bill can start to talk about the fantastic progress he and the research group have made here. Bill, over to you.
Yeah. Thank you, John. I'll start just by summarizing some of the key points highlighted by Professor Manns during his presentation, then talk a little bit more detail about hepatitis B and molecular virology of B and delta. I will share some of the exciting progress on our internal entry program. As Professor Manns said, HDV infection represents the most severe form of viral hepatitis, and there are very few current treatment options.
However, I would say that some of the data that Professor Manns shared about bulevirtide and some of the other emerging therapies is very encouraging, indicating that lowering viral load does improve patient outcomes. However, the current treatment options have drawbacks. Inconvenience, both interferon and bulevirtide are injectable, with bulevirtide being daily injectable.
The side effects of interferon have been well documented and challenges in managing patients through long treatment courses of interferon. Therefore, hepatitis delta patients would definitely benefit from a safe, simple, and effective oral therapy in the same way that many other chronic viral diseases have been managed by single-pill regimens.
This slide depicts a diagram of hepatitis B on the left and hepatitis delta on the right. I'll talk briefly about some of the similarities and important differences between these viruses. Both are small envelope viruses that replicate in the liver in hepatocytes. However, they have very different genomes and belong to different viral families. In the case of hepatitis B, it has a partially double-stranded DNA genome. It's a small virus at 3.2 kilobases.
In the case of hepatitis delta, as Michael Manns says, it's the smallest known animal virus with only a 1.7 kilobase circular RNA genome. Hepatitis B being a DNA virus versus HBV being an RNA virus. Despite its small size, hepatitis B encodes a number of proteins, including the core antigen, which we've talked about a lot at Assembly, which forms the shell around the viral genome and the nucleocapsid. HBV also secretes and produces e-antigen.
It encodes its own viral polymerase, which is able to replicate by reverse transcription with this polymerase. Three forms of surface antigen that are in the envelope of the virus, and then finally, HBx, a small protein that ensures the transcriptional activation of cccDNA in the affected cells.
In contrast, hepatitis delta encodes only the delta antigen, two forms of the delta antigen, small and large delta antigen. Then finally, as Professor Manns pointed out, importantly, HDV is a satellite virus of HBV. It requires the expression of the envelope proteins in HBV in order to be enveloped and in order to secrete infectious particles that can complete the replication cycle and infect new cells.
Stepping quickly through the viral life cycle for hepatitis delta, it enters the cell through a receptor-mediated process using the NTCP bile acid transporter. Once inside the cell, it can uncoat. It comes in as a negative stranded RNA. This can be replicated by host RNA polymerases into a positive strand of the genome. That positive strand can then be re-amplified back into more negative strands.
It can also be translated into the small and large delta antigens. Those newly synthesized antigens, along with the newly replicated negative stranded genomes, can form new ribonucleoproteins or nucleocapsids. Those can be enveloped by the surface antigen of hepatitis B and secreted. I want to highlight that there are relatively few specific targets for this virus. You'll notice it uses mostly host machinery in terms of host polymerases for replication, host transcription and translation machinery.
There are a few classical targets, such as a polymerase, a helicase or a protease, like many other viruses have. One target that's been validated is the entry procedure and blocking the interaction between the virus and its receptor. That will be the highlight for the remainder of the presentation.
We can move on to the next slide. A little bit more about NTCP. It stands for sodium taurocholate cotransporting polypeptide. As we said, it's a bile acid transporter. It has multiple transmembrane domains. It's expressed selectively on hepatocytes, and it's important for regulating the uptake of bile acids into the liver.
It was in seminal work from Wenhui Li's lab in Beijing identified NTCP as the receptor for both hepatitis B and hepatitis delta virus. A lot of elegant virology coming from Stephan Urban's lab has really characterized the interaction between the pre-S1 protein of or the large surface antigen of hepatitis B and this receptor to mediate entry.
Thinking about NTCP as a target for drug discovery, this has been well-validated by data generated with bulevirtide, spanning the laboratory through human clinical studies. I'm sharing some data on the left. These are data from Stephan Urban's lab looking at the ability of bulevirtide to block entry of delta virus into tissue culture cells expressing the receptor. In this particular experiment, they've used delta that's been enveloped by the large surface antigen and surface protein of HBV from all the different genotypes A through H, so all eight known HBV genotypes.
You can see the bulevirtide effectively blocks entry regardless of which genotype of HBV is enveloping delta virus. These in vitro results have also been reproduced in a humanized mouse model.
In this model, mice that are transplanted with human primary human hepatocytes can be infected with both hepatitis B and hepatitis delta. In untreated mice, the viruses, both viruses spread throughout the liver, and you can see they achieve quite substantial viral loads. However, in a four-week treatment course with bulevirtide in this model, you can see blocks spread of both hepatitis B and hepatitis delta to below detectable levels.
Finally, as Professor Mann shared, the efficacy of bulevirtide in clinical studies has been established. Here again summarizing some of the 24-week treatment data, and you can see approximately two-log drop in patients' viral load for delta antigen with the treatment. Bulevirtide has shown safety and efficacy, but challenges with bulevirtide include that it's a very large, complex molecule, and again, it requires daily injections.
There's an opportunity here to develop a small molecule approach and have a safe and effective once daily medication. This would improve greatly convenience for patients and has the potential to enhance treatment uptake with an easier to take treatment and also to improve diagnosis rates, which is another important factor for the field. The target profile for our entry inhibitor program is as follows. Starting with the virology, it will be a potent single-digit nanomolar inhibitor of both hepatitis B entry and delta entry.
It'll be pangenotypic for both hepatitis B and hepatitis delta. In terms of PK profile, it'll be a once daily oral medication at a reasonable dose. It'll achieve plasma trough concentrations at least tenfold in excess of the protein adjusted EC50.
Finally, it'll be suitable for a conventional formulation, and this will also allow co-formulation for use for hepatitis B or hepatitis delta thinking forward. In terms of safety profile, no clinically significant side effects, so it'll be suitable for chronic dosing in patients and low potential for drug-drug interactions. I'm gonna share some activity data for some of our inhibitors that we've discovered here at Assembly Biosciences, but first I wanna quickly walk through the assays that we use to profile our compounds.
The top depicts an entry assay looking at blocking the entry of hepatitis B virus, and the bottom represents a similar assay we're developing for hepatitis D virus. Let me just walk quickly through how the experiments are done. We seed HepG2 cells that express the HBV receptor NTCP.
We can then infect the cells with hepatitis B virus and also treat with compound. We give the virus a day to attach and infect the cells, and after which we wash off the viral inoculum along with the compounds. We give the cells four days to incubate so that they can form cccDNA and begin to have transcription and then produce proteins. At the end of the assay, we can monitor the presence of e-antigen that's been secreted into the media of the cells.
An e-antigen would be a, then a marker for successful infection, formation of cccDNA and antigen formation. If we can block the formation of e-antigen, it shows that we've blocked the entry process for the virus.
We're developing a very similar assay for hepatitis delta, with the main difference being that we infect with the delta virus instead of hepatitis B. We give the cells slightly longer to replicate delta virus and express delta antigen, and then we will have an immunoassay to measure the delta antigen in those cells. Blocking the formation of delta antigen will indicate that we've blocked the entry procedure and infection of the cells.
On the next slide, I'll share some of the activity data with some of our new compounds using the hepatitis B entry assay. I'm showing a summary of a series of five chemically differentiated small molecules.
The EC50 curves are shown on the left, and the EC50s for blocking e-antigen production as a result of blocking the entry procedure are shown on the table on the right. You can see that these are all low single-digit nanomolar inhibitors ranging between 1 and 3 nanomolar. We've also included boceprevir in these experiments as a control. As you can see, it is a very potent inhibitor at about 200 picomolar. This number agrees very well with what's been published in the literature.
I do wanna point out the boceprevir is a very large 47 amino acid peptide and, as such, it has a high molecular weight and biologics such as antibodies or polypeptides like this are typically able to drive high potency through the large number of interactions they can have by virtue of being large molecules.
Again, just to reinforce that our molecules are small molecules with a molecular weight of 500. In fact, if we adjust for the weight difference and express the EC50s in a nanogram per mL format, you can see that, on this weight-adjusted basis, that these compounds are all coming in around one nanogram per mL, very similar to boceprevir.
We're extremely excited about the potency that we have been able to achieve and with these small molecules. The status of the program, it's currently in lead optimization. It's highly resourced here at Assembly, and our goal is to push for a development candidate as quickly as possible. As I indicated, we have multiple chemically differentiated leads of single-digit nanomolar potency. We have entry assay in place for hepatitis B, and we'll have one in place shortly for delta virus.
We look forward to sharing some of that data at a meeting later this year. We're currently optimizing the DMPK properties of the molecule and pushing for that PK profile in humans that would support a once daily dose of the inhibitor.
We anticipate advancing compounds into preclinical safety profiling throughout the second half of the year. Our goal is to nominate a development candidate in the first half of 2023. Just to summarize what I've shared today, again, hepatitis delta is the most severe form of viral hepatitis, and it remains an important subgroup of HBV patients that have a high unmet medical need. Very encouraging data from recent HBV therapeutics, but there's significant room for improvement, particularly in convenience to overcome the injection and the side effects associated with interferon.
An oral once daily HBV entry inhibitor that meets our target profile would be a significant advance to currently used therapies and has the potential to increase both diagnosis and treatment rates.
As I've said, we've discovered novel single-digit nanomolar HBV entry inhibitors, and we aim to nominate a candidate within about a year's time. With that, John, I'll conclude and hand back to you.
Okay, thanks, Bill. That's great progress. As I'd always say, keep going. We're excited to talk about it now. There's been an enormous amount of progress, and the potency is there. We have to dial in all the other drug-like favorable characteristics, of course, as Bill's described to you today. Bill, you've been working on hepatitis B for many years and participated in the approval of three nucs for hep B.
You know, as I've said, I'm excited, and we are excited about the prospects of addressing the need here, which is very acute, really, for the subset of patients who are co-infected with delta and hepatitis B. Thank you both. I think it's a great time to transition into some questions and answers.
As a reminder to the participants, if you'd like to answer or ask a question today, I should say, please enter it into the Q&A chat box below the video player. To start, Professor Manns, perhaps I can ask you to share some of your expertise and ask a question or two. You know, in Hannover, at the hospital there and in Europe, where are you seeing these patients and how do they present exactly with delta?
Yeah. I mean, they are liver cirrhotic patients normally, and we have more or less two approaches. Number one is the transplant population. We have a transplant program around 100 transplants per year. Over the years, the hepatitis B patient population has changed. In the nineties, these were decompensated cirrhosis with ascites and variceal bleedings and increased jaundice. With the control of hepatitis B, we saw more and more compensated cirrhosis developing cancer.
Now we see the proportion of B with co-infection of D is increasing. This indicates that we treat widely the hepatitis B population successfully, but we cannot prevent progression of hepatitis delta. Over the years, the proportion of B patients co-infected with delta increased in the transplant population.
Number two, are our liver outpatient clinics, and here we see patients, IV drug abusers, and we also see patients, migrants from either southeastern Europe and also from countries from the former Soviet Union. Also, Romania has a high prevalence of hepatitis D in the hepatitis B population.
Okay. Thanks, Michael. Could I also ask you, and then I'm gonna ask Bill a question or two. You know, an effective oral therapy that Bill has described today that, you know, is potent and leads to a proportion of patients becoming, you know, RNA negative. How would that be perceived? How would that be thought, and would it be advantageous? Is it a good thing to do? That's what we're really asking you, really.
Of course. I mean, we learn from hepatitis B, but also from HIV. If we can suppress viral replication, we can prevent progression of the disease. I mean, the hepatitis B story is a very successful story, but also HIV. I think if on top of hepatitis B we can suppress by an oral medication, we even could think of a co-formulation of the two drugs. I'm very much convinced, and the goal of treatment is less a more than two log reduction, but normalization and undetectability of HDV RNA at the same time normalization of ALT. I'm very convinced the progression of disease will be stopped, or at least significantly ameliorated.
Mm-hmm. Okay. Thank you very much, Michael. Bill, I have to ask you know, you've been working in hepatitis B therapeutics for probably 20 years as well as other things as well. Why haven't folks and groups gone after delta previously? Why now, you know? Why have we not focused on it? If this virus is so important and so forth, why are we just focusing on it now?
Yeah. Thanks, John. I think there's a couple of factors here that play into this. The first is, you know, as Professor Manns highlighted, that we have the thought that if you could cure hepatitis B, you would be able to take care of patients' delta infection along with the cure for hepatitis B. I think right now there's an appreciation that while curing hepatitis B is still a primary goal that's incredibly important, it's still gonna take some time to achieve that cure, and these delta patients really can't wait. They should be treated as soon as possible given the aggressive course of the disease.
I think bringing the attention to treating what we can treat now, versus waiting to be dependent on hepatitis B. I think the second thing is also similar to hepatitis B in that it's a very challenging virus to study. It was very hard to study, particularly before the discovery of the entry receptor. You know, now is really a time when the molecular virology and the proof of concept from the clinical development of bulevirtide have really paved the path to you know, bring more to bear to attack this virus. I think it's a combination of things.
Mm-hmm. I think Michael also said it well, and we would agree with this 'cause we're trying to create curative treatments for hepatitis B. Once we get a curative treatment or cocktail for hepatitis B, then that will, you know, address delta because it's codependent on hepatitis B. But that's taking longer, and we're working hard on that, and this is something we should be doing in the interim, and it's very important.
Bill, just, you know, I mean, I don't wanna rehash this too much, but if you keep going at this pace, you achieve your goal. We get there. We have a single digit, you know, nanomolar potent oral drug once a day. I mean, you know, why and what are the advantages over bulevirtide and interferon, et cetera?
Really, the advantage, I think, will come primarily down to convenience for the patient. You know, we've highlighted that bulevirtide is effective, but it is a complex molecule. It does require, you know, preparation of a lyophilized drug and daily injection, refrigeration. I think greatly simplifying this for patients is a strong advantage. You know, we saw this in many other viral diseases, particularly in HIV and HCV, where simplifying the regimen into a single oral pill really transformed the treatment of the disease. That's the same type of thing we'll be trying to achieve for delta.
I think both of you have said that today as well. Michael, you mentioned in your slides today, Professor Manns, I should say. In your slides today and mentioned a couple of times under diagnosis.
Yeah.
You know, it's screening. Obviously, in Europe, you're screening everybody with hepatitis B. You know, how underdiagnosed is it, really? I know this is a bit of a conundrum, and we don't know exactly how many folks there. What are the factors here, do you think?
Okay. First of all, for a long time, it certainly was underdiagnosed in the United States. The diagnostics reagents have not been available, not in the United States. There are other countries, for example, in sub-Saharan Africa, we have no idea in some areas whether there is delta co-infection or not. The other thing is, if patients with hepatitis B come to a practitioner, to a GP, they don't know delta. If a patient comes to tertiary referral center with a hepatitis cirrhosis, I mean, he is B positive, he will be tested for delta. Normally, we also have this in Germany, that a general practitioner, he doesn't think of delta.
Yeah. No, I agree. Whenever I ordered a delta test in my past life, I knew I was gonna get called from the lab to explain and be asked what it was. There was an inherent roadblock to getting easy access to testing and thinking about it. GPs just didn't think about delta.
Yeah.
Yeah, I agree with you there as well. Look, we have had a number of questions come in through the chat room, so perhaps it's a good time to start and address them. Perhaps, Professor Manns, I'll start with you. We've had quite a few questions around could you please comment on which setting you could use such a drug as described, an oral entry inhibitor. Specifically, could it be used in combination with interferon or with other agents or-
Yeah.
Would it be used alone, et cetera?
No, no. Well, I think this bulevirtide is approved, conditional approval, as a monotherapy. I think in the future, in particular, when we think of curing hepatitis D, I mean, at the moment, we have as an endpoint, both by FDA and the recommendations by EASL, AASLD, more than two log reduction. However, we know that clearing delta is what we would like to see.
There is one issue we need to discuss, and this is, we have since the treatment of hepatitis B with interferon and also in hepatitis C, we have 12 weeks after the end of treatment as an endpoint. For example, if hepatitis C RNA is negative 12 weeks after the end of treatment, this is cure.
If in the hepatitis B, if e-antigen positive, if 24 weeks after the end of treatment, there is e-antigen negativity, normal ALT, we know that interferon has been efficacious. In delta, the story is a little bit different. Heiner Wedemeyer's group, together with Dr. Heidrich, they have found out that if you look at our HIDIT-1 study long-term, that there may be relapses beyond 24 weeks.
This is an argument that there will be, in the future, presumably a long-term treatment, and there is an oral drug given daily together with interferon. I could think of. I could think of also giving the combination for a certain time period, let's say 24 or 48 weeks, and then continuing with the oral drug in order to prevent relapse.
We don't know how the final schedule will look like, but I think the combination, this is the treatment for combination.
Thank you, Michael. I agree. You could give it with interferon and try and have more of a sustained response or give it with monotherapy. If Bill's group can design a drug that has favorable characteristics without accumulation, we could use it in people with cirrhosis and potentially more advanced liver disease. You know, we can't use interferon in that setting.
No.
and so forth right now. But that all has to be determined and so forth. There's something else I wanna get back to if we have time, but we'll see if we have time. There's a few questions-
For people more specialized, also, these oral drugs could be useful to prevent reinfection after transplantation.
Yeah.
There's also to touch a little bit on transplantation. We know that hepatitis B can be prevented by giving oral drugs. We can prevent reinfection, but we cannot prevent reinfection of delta. Therefore, it's so important to treat delta before transplantation. Also, the data from Mario Rizzetto, Italy, have shown that there may be a reinfection of the graft without co-infection of B. I think there is also an indication for such an oral drug, which would be very welcome in the field.
Very good idea. Thank you. Bill, the next question's for you, and it's about bandwidth and understanding that delta is a new area for Assembly. Just can you briefly elaborate on the priority of this versus what we're doing with hepatitis B and our existing hepatitis B pipeline?
Yeah. Thanks for the question, John. It is a new area for us, but one that's, you know, overlaps very nicely with HBV in terms of both the research and the development aspects. Something that allows us to make progress on both viruses simultaneously. In terms of resourcing, this is an important program for us, and we are resourcing it to move ahead aggressively, as I said, with the goal of having a development candidate in the first half of next year.
It's still important for us to move other mechanisms forward for hepatitis B, and we're looking for ways to leverage the expertise we have in the research and the development group in terms of treating other viral diseases as well, so this is part of our overall building out of and broadening the pipeline at Assembly, and, you know, we're excited about all of the new programs we have.
We do expect this particular program will be the next development candidate that we deliver, but we'll be excited to tell you more about our second target for hepatitis B in the coming months, as well as expand a little bit about what we're doing on other viruses.
The process here. Thanks, Bill.
Mm-hmm.
The process here over the last 2 years is to build you know, a world-class best virology, molecular virology research and drug development research team, and that's what Bill has done. That cadre and group of highly focused, qualified people has allowed us to do things such as what we're talking to you about today over the last 6+ months and not distract from our primary mission of trying to cure hepatitis B. This is not a program at the expense of our other hepatitis B programs.
I hope I've made that clear as well in a different way, Bill. Now, this is a question I knew we're going to have for you, Professor Manns, and I think we should discuss it a bit. Could you describe the increased bile salts-
Yeah.
-that's observed with bulevirtide?
Yeah.
Is it a problem clinically, how is it managed, and would you expect for us to see this with a small molecule, which I think Bill can answer as well, but.
First of all, I think the virus is taken up by this NTCP receptor. I think if you don't see an increase in bile salts, then the drug is not efficacious via that mechanism. I think this is inevitable that there's an increase in bile salts. From bulevirtide, we know that it may be transient, but on the other hand, this may be a side effect we have to take into consideration. The treatment could be, for example, cholestyramine, trying to bind the bile salts in the enterohepatic circulation.
For those not familiar with it, the bile salts are circulated, they are secreted via the bile, come into the gut, and then are uptaken in the ileum to 90%, and if you bind them with drugs like cholestyramine, which itself are not taking up in the gut, then they're excreted through the normal enteral route. Other applications would be to give antihistamines, and I think these two should be fair enough to cope with this side effect. Nevertheless, it also tells us that the drug is efficacious.
Do many people have itch, Michael, with the drug? When they've received the drug? It's not in the. When you look at the documents for regulatory-
No.
Approval, it's very rare, right?
It's rare, it's transient, and it normally is at subclinical levels.
Okay.
I mean, this is also an interesting phenomenon. I think it's not a problem for the drug. It was not a problem for the approval, and certainly it's not life-threatening. Also, the itching, for example, there's also the idea that it's not only due to bile salts. There are very interesting data coming out of Dr. Beuers's laboratory in Amsterdam, there are other mechanisms involved leading to pruritus in cholestatic liver disease. It's not just based on bile acid increase.
Thanks, Michael. Bill, are we gonna see this with the small molecule approach?
Yeah. I think as Michael said.
Yeah.
We could expect to see this as well.
Okay.
It would be a marker of the pathway of inhibition. As Michael and you have highlighted, it's generally not an issue.
Yeah.
Tolerable.
The other thing I would just add to the discussion and to answer the question here is that there've been a number of rare individuals described that have a autosomal recessive absence of these receptors, and they have high levels of bile acids, and some of them are actually normal and have normal levels of bile acids. Some of them are transient in the pediatric population, then they return to normal. But it's not an issue in those people who have complete deficiency or block, you know, no receptors, which is the same as the drug. So I think it's not a serious problem as Professor Manns has described as well today.
John.
Yeah.
I think once we discuss in such detail, I think, first of all, the inborn errors, the BRIC diseases, they are pediatric diseases. They should not develop delta. The other thing is there may be an issue, for example, we know that in the heterogeneous genetic background, that sometimes these deficiencies are associated with the cholestasis of pregnancy.
Maybe in the future, patients with cholestasis in pregnancy in their history should be cautious taking these drugs. This is a very small population of patients. Still, I think, for example, using cholestyramine or other drugs, this should be manageable. Minority of patients.
Thank you. Now there's two questions here that are the same. Bill, you and I have talked about this, so I'm gonna let you start, and then I'll chime in as well. The two questions are really about, you know, this HBx entry of hepatitis B as well.
Mm-hmm.
You know, could it be used in hepatitis B? What would we do with it, as well as the delta population we have to talk about today? Could it be complementary to standard of care for hepatitis B? Could it be complementary to core inhibitors? Actually, I'll tell you that Bill and I have discussed doing a triple combination trial with bulevirtide previously as well. Thoughts and comments on that. There's a couple of questions around this because they share similarities in entry.
Yeah. Thanks, John. I mean, this is one of the things that attracted us to this program and why we decided to move forward with this program, because it does give us another potential to intensify the antiviral pressure on hepatitis B beyond nucleosides and core inhibitors. It certainly works at a distinct step. You know, it blocks the virus before it enters the cell, whereas core inhibitors work at several points inside the cell.
They can prevent the assembly of new virus. They can also destroy any virus making it into the cell by affecting the nucleocapsid and resulting in the degradation of HBV DNA. It works on two separate steps.
I think people often say, "Well, if it works on two steps that are next to each other in the viral life cycle, is that gonna be effective?" I think you only need to look at the results we've established here with core inhibitors and nucleosides, which work at adjacent steps in the viral replication cycle, with assembly being immediately preceding the reverse transcription step that Nucs work on. Yet we see clearly additional antiviral benefit in patients that are treated with that combination. Certainly adding a third mechanism, you know, is very rational in terms of intensifying antiviral pressure.
We will explore this. There's another very important piece of information. Bulevirtide. I apologize. There was a study done in hepatitis B monoinfected patients. At the 10 mg dose, which is the higher dose, it wasn't approved, but it's also a more effective dose. Some of Professor Manns's slides showed that today as well. Given as monotherapy for 12 weeks, it reduced HBV DNA to the same level that entecavir did. The same proportion of patients had a reduction in HBV DNA of greater than one log at 12 weeks. It was about the same proportion of patients. Small study.
that shows you that just blocking entry of hepatitis B had a significant reduction by preventing cell to cell, new cell infection or cell to cell spread in reducing HBV DNA and viral replication. There is an effect there. Whether that effect has additional benefit in trying to shut down all elements of viral replication at multiple steps, et cetera, for hepatitis B, we'd be fortunate enough to be able to study that, I think.
Mm-hmm.
In a particular population. We will do that. There's another question for you, Professor Mann. We're getting to the end of the time soon here I think, but this is a good one. Do we know for certain that complete viral suppression of hepatitis B alone, you know, a cure of hepatitis B, I presume, is enough or not enough to eliminate delta infection? And if not, why not, I suppose?
Okay. First of all, we don't know. If I would have to guess, I think complete suppression means undetectable HBV DNA in serum. This does not mean undetectable HBV DNA in the liver cell. I think we cannot predict. For the time being, I think all the means we have available to suppress hepatitis B will not be sufficient to eliminate or cure hepatitis delta.
Yeah, I think we would agree with you. If you can shut down all viral replication and no cells are getting infected, then over time, surface antigens should decline.
Yes.
residual infected cells should diminish, and you will need lots of surface antigen to get rid of
Okay.
All delta-infected cells, I agree.
John, I could also modify your question. I think suppressing HBV DNA is not enough. You need to have a clearance of surface antigen, and best with the seroconversion. I would say HBV treatment is enough.
Yeah.
We have learned that in particular with the Nucs, this is a rare event.
Hopefully, we'll get there one step at a time.
Yes.
We will work on it. I think. Look, sorry, Michael, I interrupted you.
Yeah, I would say we have to go both ways because we don't know what will be successful. Those patients who have delta associated cirrhosis now, they cannot wait and bet for this approach on B.
Mm-hmm.
If we look at hepatitis C, the virus was discovered by Michael Houghton and his group. The patent was developed mainly aiming at the hepatitis C vaccine, not as therapeutics. So far, we don't have a vaccine for C, but we have efficacious treatments. If we look at the SARS pandemic, we had a vaccine within 10 months, but we don't have efficacious treatment now. Therefore, we cannot predict, and we have to go both ways because there are so many patients that cannot wait.
Thank you very much. With that, I think we'll wrap things up for the day. It's getting late in Germany, I know, and we're incredibly grateful to you, Michael, for being so generous with your time and your thoughtful insights into viral entry inhibition for hepatitis delta. Thank you once again.
Pleasure.
Bill and I and the research team are excited about our activities in this area and our path towards the clinic as we've talked to you today. We look forward to sharing our progress with you on this program at an upcoming scientific meeting later this year also. Also, we plan to introduce, as shown, additional research programs by mid-year. Stay tuned, please. We are thrilled to be broadening the scope of our pipeline to complement our portfolio of potent core inhibitors, including clinical candidates which have demonstrated favorable safety and antiviral activity to date.
To that point, during 2022, this year, we expect to initiate a phase I-B study of 3733, our next-generation core inhibitor, and have interim data to report by year-end. We also plan to advance 4334 into the clinic.
This is our most potent core inhibitor, designed with a profile that's potentially best in class as well. We expect also the initiation of a phase II triple combination study under our collaboration with Antios, evaluating vebicorvir plus NrtI and Antios' active site polymerase inhibitor or ASPIN. Lastly, we anticipate interim data on treatment data from our phase II triple combination studies evaluating vebicorvir plus NrtI with RNAi and interferon respectively. The RNAi study is part of our collaboration with Arbutus and recently completed enrollment.
We are leveraging in the strengths of our team and their track record in virologic discovery and drug development to further strengthen our portfolio. In doing so, we are building important momentum and progress during 2022, and I look forward to updating you further as the year progresses. This concludes our event. Thank you for joining us today.
I hope you found it helpful and for your support of our company, Assembly Biosciences. Thank you very much.