Vir Biotechnology - Q3 2024

Transcript

Operator (participant)

Financial results and business update call. As a reminder, this conference call is being recorded. At this time, all participants are in a listen-only mode. After the speaker's presentation, there will be a question-and-answer session. If you would like to ask a question during this time, simply press the star key followed by the number one on your telephone keypad. If you would like to withdraw your question, press star one again. I will now turn the call over to Rich Lepke, Senior Director, Investor Relations. You may begin, Mr. Lepke.

Richard Lepke (Senior Director of Investor Relations)

Thank you, and good afternoon. With me today are Dr. Marianne De Backer, our Chief Executive Officer, Dr. Mark Eisner, our Chief Medical Officer, and Jason O'Byrne, our Chief Financial Officer. Before we begin, I would like to remind everyone that some of the statements we are making today are forward-looking statements under the securities laws. These forward-looking statements involve substantial risks and uncertainties that could cause our clinical development programs, future results, performance, or achievements to differ significantly from those expressed or implied by such forward-looking statements. These risks and uncertainties and risks associated with our business are described in the company's reports filed with the Securities and Exchange Commission, including Forms 10-K, 10-Q, and 8-K. I will now turn the call over to our CEO, Marianne De Backer.

Marianne De Backer (CEO)

Thank you, Rich. Good afternoon, everyone, and thank you for joining us today. I'm pleased to provide an update on the significant progress we've made this quarter, beginning with the successful closing of our exclusive worldwide licensing agreement with Sanofi. This landmark agreement includes three clinical-stage masked T-cell engagers and the use of Sanofi's proprietary PRO-XTEN protease cleavable masking platform for oncology and infectious diseases. This strategic move aligns seamlessly with our mission to use the power of the immune system to fight disease. We believe that the three dual-masked T-cell engagers, VIR-5818 for HER2, VIR-5500 for PSMA, and VIR-5525 for EGFR, have the potential to be best-in-class therapies.

These investigational treatments aim to minimize toxicity challenges typically associated with T-cell engagers, allowing for higher dosing and thereby enhancing efficacy. As part of this agreement, we have welcomed key employees from Sanofi, which bring extensive scientific and development expertise in oncology and the PRO-XTEN masking platform technology. These talented individuals have quickly proven to be an excellent fit within our organization. We believe that their expertise, combined with our deep understanding of T-cell immunology, our robust infrastructure, and leading machine learning and antibody engineering capabilities, will create significant synergies.

Moving on to our mid-stage clinical pipeline, we are making strong progress across our hepatitis programs with important upcoming data readouts. I'll now highlight our recent progress in the ongoing phase II SOLSTICE trial in patients with chronic hepatitis delta. Hepatitis delta represents a highly promising growth opportunity for Vir, marking the next significant inflection point in our journey toward becoming a fully integrated and sustainable commercial company.

Much like other orphan disease markets, the HDV market is characterized by significant unmet medical needs and severe clinical outcomes for patients. This underscores an opportunity for innovative and impactful therapies that address critical health challenges and offer substantial value to both patients and the healthcare system. We estimate there are approximately 100,000 people living with hepatitis delta in the United States and approximately 200,000 in Europe. Despite the severe and often life-threatening impact of HDV, patients currently have very limited treatment options. There are no approved therapies in the U.S., and in Europe, the only available treatment requires daily self-administered subcutaneous injections, presenting challenges for long-term patient compliance and quality of life.

Based on the preliminary phase II clinical data we have shared to date, we believe our combination regimen of Tobevibart and Elebsiran is highly differentiated compared to the current standard of care and has the potential to be a transformative treatment option for these patients in need. As we continue to advance this promising treatment, we anticipate an increase in both diagnosis and treatment rates. Feedback from physicians and advocacy groups has highlighted a growing interest in reflex testing for hepatitis delta. Reflex testing involves automatically testing for hepatitis delta in patients who test positive for hepatitis B without requiring a separate order from the healthcare provider. This proactive approach ensures early identification of HDV infections, even in regions like the United States, where treatment options are currently limited.

By identifying patients early, we can help ensure they receive timely treatment once a therapy is approved. While we are at the early stages of driving this awareness, we aim to improve early diagnosis and pave the way for effective treatment outcomes for patients with hepatitis delta as our HDV program advances closer towards a potential approval. We are committed to partnering with key stakeholders across the healthcare landscape to advocate for and adopt these testing practices. Looking ahead, we will present data from the SOLSTICE trial at the AASLD conference taking place November 15th to 19th in San Diego. We are making excellent progress advancing this program in the clinic and have engaged with the FDA to discuss our planned registration program in HDV, which is expected to begin next year.

Next, I'd like to address our functional cure program for chronic hepatitis B, which represents another substantial opportunity for our combination regimen of Tobevibart and Elebsiran with or without pegylated interferon alpha. Our goal is a functional cure in this setting, defined as a sustained loss of detectable hepatitis B surface antigen and hepatitis B virus DNA after a finite course of treatment. There are an estimated 1.6 million hepatitis B patients in the United States alone and approximately 254 million globally. We are looking forward to reporting end-of-treatment data from the MARCH Part B trial in a late-breaking presentation at the upcoming AASLD meeting in November. This end-of-treatment data will be followed by the functional cure data readout in the Q2 of 2025.

Based on KOL feedback, our target for a functional cure is 30% for the interferon-containing regimen and 20% for the regimen excluding interferon. Before I close, I would like to provide an update on our upcoming events and reaffirm our commitment to keeping you informed about our progress. While we had initially planned to host an R&D day in the Q4, we will instead conduct an in-depth investor event focused on our hepatitis franchise in November. Given the addition of the T-cell engagers to our portfolio and the subsequent reprioritization of our pipeline, we have adjusted our plans. We now intend to discuss our T-cell engager programs at a dedicated investor event in the Q1 of 2025. This timing also allows us to present initial clinical results, ensuring we provide insights into our progress and the future prospects of these programs.

As mentioned, we will host an exclusively hepatitis-focused investor event immediately following the AASLD conference in November. During this event, we will provide detailed updates on both the MARCH and SOLSTICE programs. This focused approach will allow us to delve deeply into these two critical development programs and their implications for patients and our broader clinical strategy. We understand the importance of clear and timely communication with our investors, and we are committed to keeping you updated on all the significant developments. Finally, I'm thrilled to have welcomed Jason O’Byrne as our new Executive Vice President and Chief Financial Officer earlier this month. Jason is an accomplished executive with more than 20 years of experience in finance and operations and a proven track record in financial strategy across public companies.

His exceptional leadership and focus on excellence in execution make him a perfect fit as we embark on the next chapter for our organization. Since joining Vir, one of Jason's key priorities has been to ensure continued disciplined capital deployment and financial stewardship. As we recently announced, we have implemented a strategic restructuring initiative to prioritize our clinical-stage pipeline opportunities and streamline our operations. These efforts are allowing us to allocate our resources more efficiently and focus on our core programs. In closing, I couldn't be more optimistic about Vir's future and the potential impact of our innovative therapies.

We have a strong balance sheet, which allows us to fund operations through our next major inflection points. We are prudently managing our expenses with a focus on our most promising programs and maximizing shareholder value. I would like to thank our dedicated team, including our new colleagues, for their hard work and our investors for their continued support. With that, I'll now turn the call over to our Executive Vice President and Chief Medical Officer, Mark Eisner, to provide an update on our clinical development programs and pipeline.

Mark Eisner (CMO)

Thank you, Marianne, and good afternoon, everyone. Let's begin with the SOLSTICE trial in hepatitis delta. As a reminder, we presented strong preliminary data from our phase II SOLSTICE trial in HDV at the EASL Congress in June. In our rollover cohort of six non-cirrhotic participants, we reported that all six achieved virologic suppression below the lower limit of quantification, and five out of six achieved target not detected, indicating no measurable presence of HDV RNA. Additionally, three out of six achieved ALT normalization. Durable virologic suppression was observed in the combination rollover cohort, suggesting the potential for sustained antiviral activity. There are 32 participants in the de novo combination cohort, and 33 participants are in the monotherapy cohort.

At the time of the analysis, 11 participants in the de novo combination cohort and 7 participants in the monotherapy cohort had reached 24 weeks of treatment. There were no discontinuations in the combination cohort. After 24 weeks of treatment, all 11 participants in the de novo combination cohort achieved virologic suppression below the lower limit of quantification, and six out of 11 achieved target not detected. Seven out of 11 also achieved ALT normalization. From a safety perspective, we observed no treatment-related serious adverse events or ALT flares in either the monotherapy or de novo combination treatment regimens. The majority of adverse events were transient and mild, grade 1 or 2, with a low incidence of injection site reactions.

Taken together, these preliminary data are extremely promising as all three cohorts demonstrated rapid and sustained virologic responses. We will be sharing the full dataset for both cohorts of approximately 30 participants at 24 weeks of treatment, as well as available data for participants beyond 24 weeks of treatment at AASLD. We are pleased to have received fast-track designation from the U.S. FDA for our combination of Tobevibart and Elebsiran. We're also actively exploring all possible acceleration pathways to bring this promising investigational therapy to patients as quickly as possible. We have recently engaged with health authorities to align on our clinical development strategy for Hepatitis delta. Based on these discussions, we are actively working to expedite the initiation of our registrational program.

We look forward to sharing more information at our hepatitis-focused investor event following the AASLD conference. Moving on to our phase II program for chronic Hepatitis B. At AASLD, we look forward to sharing the end-of-treatment data from the MARCH Part B trial, which evaluates our doublet and triplet regimens. The data will include approximately 50 participants receiving our combination treatment and approximately 30 participants receiving the combination therapy plus interferon. This readout will be followed by post-treatment data in the Q2 of 2025, which will allow us to assess functional cure for both regimens. Now, let's transition to oncology and discuss the T-cell engager programs. As we described in our Q2 call, the agreement with Sanofi provided us with a robust portfolio of assets targeting clinically validated antigens in oncology.

I'll briefly touch on the status of each program. VIR-5818, our dual-masked HER2 CD3 T-cell engager, is a highly differentiated asset with the potential to address significant unmet needs in HER2-expressing cancers. As the only masked HER2 T-cell engager currently in clinical development, VIR-5818 is designed to offer lower off-tumor toxicity, allowing for higher doses and potentially improved efficacy compared to existing HER2-targeted therapies. There is a significant unmet need in HER2-positive cancers, particularly in metastatic breast cancer and metastatic colorectal cancer. The phase I study is ongoing, evaluating VIR-5818 as both a monotherapy and in combination with pembrolizumab, initially in a basket of solid tumor indications. The study is currently being conducted at 10 active sites in Europe and Australia, and we are making good progress with continued dose escalation.

We anticipate sharing preliminary monotherapy data in the Q1 of 2025. VIR-5500 is a dual-masked PSMA-directed T-cell engager currently in phase I clinical trials. Prostate cancer represents a significant disease burden, with many patients in need of more effective and well-tolerated treatment options. As the only dual-masked PSMA-directed T-cell engager currently in clinical development, VIR-5500 is designed to offer lower off-tumor toxicity, allowing for higher doses and potentially improved efficacy compared to existing PSMA-targeted therapies. The study is currently ongoing, evaluating VIR-5500 as a monotherapy in a step-up dose escalation design with the potential to expand into combination therapy. The phase I study for VIR-5500 is earlier in its progression, with fewer participants compared to VIR-5818. We anticipate sharing early monotherapy data in the Q1 of 2025.

Finally, VIR-5525, a dual-masked EGFR CD3 T-cell engager, has a cleared IND, and we're preparing to initiate the phase I clinical study. Despite available treatments, the unmet need for patients with EGFR-expressing tumors remains high. The initial target tumor types for VIR-5525 are metastatic head and neck squamous cell carcinoma, metastatic squamous non-small cell lung cancer, and metastatic colorectal cancer. We believe that VIR-5525 has the potential to provide a safe and tolerable treatment option for patients in the second line and beyond settings for these difficult-to-treat cancers. We are on track to initiate enrollment in a phase I clinical study in the Q1 of 2025. With that, I'll now hand the call over to Jason.

Jason O’Byrne (EVP and CFO)

Thank you, Mark, and thank you, Marianne, for the warm welcome. It's an honor to join the talented Vir team at this important time in the company's evolution. I have long admired Vir's commitment to preventing and treating serious infectious disease and the team's impressive history of proven successful execution. Today, as Mark just shared, Vir continues its focus on infectious disease while also expanding into oncology with the addition of three T-cell engager assets and the underlying PRO-XTEN masking platform. In my role as CFO, I look forward to working alongside the executive team and all the dedicated Vir employees to deliver meaningful benefit to patients and to create shareholder value. As Marianne mentioned, one of my early focus areas will be disciplined capital deployment and financial stewardship.

I am confident that with our strong financial position, compelling clinical programs, and exceptional team, we are well-positioned to deliver Vir's mission. I will now share highlights of the Q3 2024 financial results. R&D expenses for the Q3 of 2024 were approximately $195 million compared to $145 million for the same period in 2023. The increase was primarily driven by approximately $103 million of expense related to the Sanofi transaction this quarter, partially offset by reduced clinical development and manufacturing costs associated with the discontinued flu asset, VIR-2482. SG&A expenses for the Q3 of 2024 were $25.7 million compared to $40.9 million for the same period in 2023. The decrease was largely related to cost-saving initiatives announced at the end of 2023.

Restructuring long-lived asset impairment and related charges for the Q3 of 2024 were $12.7 million compared to $3.4 million for the same period last year. The increase was primarily driven by our August 2024 restructuring severance charges and asset impairment charges related to the closing of our Portland, Oregon facility. We ended the Q3 with cash, cash equivalents, and investments of approximately $1.19 billion compared to $1.43 billion at the end of the Q2. Excluding the effects of the Sanofi transaction, the decrease in cash and investments during the Q3 was approximately $66 million, including the effects of the Sanofi agreement. The total decrease in cash and investments during the quarter was approximately $245 million, which included $104 million in cash payments made to Sanofi at closing, plus a $75 million escrowed milestone payment.

The escrowed $75 million milestone is subject to VIR-5525 achieving first-in-human dosing by 2026, and that amount was reclassified to restricted cash in the quarter. As we approach the latter part of the year, we are adjusting our GAAP full year 2024 expense guidance to a range of $660-$680 million, which includes the Sanofi transaction expenses, stock-based compensation expense, and restructuring charges. Excluding those three items, our updated net guidance is now modestly lower at a range of $430-$470 million compared to our Q2 guidance of $450-$500 million. With that, I'll turn the call back over to Rich to begin the Q&A session.

Richard Lepke (Senior Director of Investor Relations)

Thank you, Jason. This concludes our prepared remarks, and we will now start the Q&A section. Please limit questions to two per person so that we can get to all of our covering analysts. I'll turn it over to you, Operator.

Operator (participant)

Thank you. At this time, we will begin conducting our analyst Q&A session. For our analysts, please raise your hand by pressing star one to indicate you would like to join the queue if you've not done so already. Once you hear the operator announce your name, you can unmute your line and ask your question. We'll go first to Paul Choi at Goldman Sachs.

Paul Choi (Executive Director at Human Capital Management)

Hi. Good afternoon, and thank you for taking our questions. My first question is, can you just update us on the status of your planned end-of-phase two meeting with the FDA? Apologies if I missed a mention of it in the press release. So I was just curious what the status of your regulatory discussions was. And my second question is for your new T-cell engager program for 5818. Can you maybe comment on how you're thinking about the relative measures you're looking for for both the monotherapy versus the Pembrolizumab combination? Thank you very much.

Marianne De Backer (CEO)

Okay. Thank you very much for that question, Paul. I'll give it to Mark, our CMO, to answer those questions.

Mark Eisner (CMO)

Yeah. Thanks for the question, Paul. We have engaged with the FDA, as you mentioned. We are just putting the very finishing touches on our clinical development program, and we expect to be able to share further details about that at our hepatitis-focused investor meeting on November 19th. In terms of the T-cell engager program and the 5818 HER2 CD3 program in particular, your question about efficacy is a good one. We are planning to share preliminary monotherapy data from that program, also the PSMA program, in quarter one next year, and at that time, we'll be able to provide a bit more perspective on the data.

Paul Choi (Executive Director at Human Capital Management)

Okay. Thank you.

Operator (participant)

Next, we'll move to Eric Joseph at JPMorgan.

Eric Joseph (VP and Equity Research Analyst)

Oh, thanks. If I remember correctly, just in terms of the pivotal path forward in HDV, you previously outlined a randomized study with Hepcludex as a comparator arm. I guess based on your latest regulatory interactions, should we still kind of carry out that expectation? And I guess within that, how should we be thinking about sort of the continued inclusion of or evaluation of combination or monotherapy with Tobevibart? Thanks.

Mark Eisner (CMO)

Yeah. Thanks for the question. So as we've stated before, we are committed to going forward with the combination of Tobevibart and Elebsiran because we achieve deep and sustained virologic responses with the combination regimen. And to remind everyone, we got fast-track designation for the combination regimen for the FDA. In terms of further details of the program, we do plan on discussing this in more detail in our investor event around the AASLD.

Eric Joseph (VP and Equity Research Analyst)

Okay. Great. Thanks very much.

Operator (participant)

We'll move next to Michael Ulz at Morgan Stanley.

Michael Ulz (Executive Director at Biotechnology Equity Research)

Yep. Good afternoon. Thanks for taking the question as well. Maybe I could just ask a follow-up on the phase three trial design and your interactions with the FDA. I'm just curious if you're getting any feedback that might be unexpected at this point, or are things just on track and you're going to sort of reveal the final details at your investor event? Thanks.

Mark Eisner (CMO)

Yeah. Thank you for the question. I will say we had a very productive meeting with the FDA. I think we aligned with them very closely on the plan. And we'll be prepared to share more details at the investor event around AASLD.

Michael Ulz (Executive Director at Biotechnology Equity Research)

Great. Thank you.

Operator (participant)

Next, we'll go to Gena Wang at Barclays.

Gena Wang (Managing Director and Senior Equity Research Analyst)

Thank you for taking my questions. I have two questions. The first one is regarding the HDV data. Thank you very much for putting the data together from the prior study. So slide 21, you lay out the several data points here. I assume the key focus for us should be the target not detected rate, and also ALT normalization. Should we expect those are the benchmark, and that should be the minimum level should achieve with more patient data now, 32 patients, 33 patients at the week 24? And my second question is regarding the T-cell engagers. And I remember, Marianne, you said you saw some initial phase one data when the Sanofi deal discussion was ongoing. So now with the next year data update, have you seen the more patient data? And with the more patient, does the monotherapy activity hold as your initial expectation? Okay.

Marianne De Backer (CEO)

Thank you very much, Gena. Mark, do you want to comment on the HDV data?

Mark Eisner (CMO)

Absolutely. To source the study of HDV, we are going to have an oral presentation at the AASLD meeting, which I think will give a lot more information, particularly all the patients who made it through week 24 of the study and some of the patients beyond that. We're going to be presenting those data. In terms of your question around TND, yes, absolutely. I mean, getting below the limit of quantification target not detected means there's undetectable delta viral levels.

That is kind of the most rigorous measurement that's out there. Our combination regimen, what we revealed at EASL, has a very, very profound reduction in the viral load and achieving high rates of target not detected above 50% at week 24. In terms of ALT normalization, that's also important, and those data will be included.The FDA guidance includes a composite endpoint of TND plus ALT normalization. So that will be data we will also present at the AASLD meeting coming up.

Marianne De Backer (CEO)

Yeah. And then on your question related to the T-cell engagers, Gena, remember that our agreement with Sanofi closed on September 9th. So we are in the midst of transitions, for example, trial sponsorships and so on. Obviously, we have all the data available on the programs. And as I mentioned, we will be in a position to share initial data on the monotherapy of both the 5818 assets in the Q1 of 2025.

Operator (participant)

We'll move next to Alec Stranahan at Bank of America.

Alec Stranahan (Senior Analyst at Equity Research)

Hey, guys. Thanks for taking my questions. Two from me as well. I was hoping you could help frame the sort of data we should expect for 5818 and 5500 in the Q1. Will it be mostly focusing on maybe safety and dosimetry, or could we see some initial efficacy metrics as well? And if you could speak to how the dual mask for your assets might benefit your ability to reach a higher target dose? Is this baked into the dose escalation, or is driving to reach MTD maybe not even the right way to be thinking about things here? Thank you.

Mark Eisner (CMO)

Sure. So in terms of your first question, as we stated, we are planning to share preliminary monotherapy data from the ongoing phase one studies, both for VIR-5818, the HER2 program, and VIR-5500, the PSMA T-cell engager program. At this point, we're not really providing more color on that, but we will be providing those data updates in quarter one of next year. And then your question about the dual masking, I think, is important. All of our programs do have the dual masking. So we're masking both the CD3 T-cell engager part of the molecule and the tumor antigen binding part of the molecule.

So the working hypothesis here is that that will allow us to achieve a better therapeutic index, so higher levels of safety, I mean, higher levels of efficacy with good safety. As we mentioned before, for the HER2 program, we're the only dual mask program in clinical development for PSMA. The Janux program masks the CD3 part, but we use the PSMA unmasked. So we think we may have a differentiated asset in terms of our dual masking of the PSMA molecule.

Alec Stranahan (Senior Analyst at Equity Research)

Thank you.

Operator (participant)

We'll go next to Roanna Ruiz at Leerink Partners.

Roanna Ruiz (Senior Research Analyst)

Hey, this is Nick Gasic on for Roanna. Thanks for taking our questions. Maybe first on the HDV phase three trial design, just thinking about the target patient population, are you going to be focusing on both cirrhotics and non-cirrhotics? And I guess, are there any specific baseline characteristics you could enrich for here? A quick follow-up on HBV after that.

Mark Eisner (CMO)

Sure. So thanks for the question. So in SOLSTICE, we've presented data including both cirrhotic and non-cirrhotic patients, CPT-A. And back in EASL, when we presented these data, you'll recall that the antiviral efficacy effect on ALT was very, very good in both cirrhotics and non-cirrhotics. If anything, the cirrhotic patients fared a little bit better. So clearly, we want to base our phase three program on the observations from the phase two program. So we would include both cirrhotic and non-cirrhotic patients.

In terms of baseline characteristics that kind of predict response and any enrichment, I think we'll be able to provide more color on that at our investor-focused hepatitis presentation around AASLD. So stay tuned for more detail there. Got it. That's helpful. And then at HBV, looking ahead, it's a read-through to the 48-week end of treatment data as to the possible functional cure data in the Q2 of 2025? I'm just curious what sort of HBs antigen suppression rates you could see at the 48 weeks, how that might mature heading into the off-treatment data in Q2. Thanks. Yeah. No, that's a really good question. So just to summarize, we'll have the end-of-treatment data for the doublet of Tobevibart and Elebsiran and the triplet with pegylated interferon in addition at the upcoming liver meeting in San Diego.

The functional cure data, as you said, comes in Q2 next year, so really, what we said before for functional cure is we're looking for a minimum of a 30% in the triplet, functional cure 20% in the doublet. In terms of end-of-treatment data, it's clear that there is going to be, at least based on prior programs of various mechanisms of action, there's a drop-off between end-of-treatment and 24 weeks post-treatment to our functional cure, but predicting that drop-off is not straightforward, and there are no clearly established markers to do that, so what I'd say just in summary is we will have the end-of-treatment data soon. The functional cure rate will take a little bit longer, Q2 next year, and taken together, that will give a very complete picture of the regimens and what they can achieve for HBV patients.

Operator (participant)

We'll move next to Phil Nadeau at TD Cowen.

Phil Nadeau (Managing Director and Senior Biotechnology Research Analyst)

Good afternoon. Thanks for taking our questions. Two from us. So first, on the HDV pivotal program, you've suggested you'll be able to give us an update at the AASLD analyst meeting. Will you have the final trial design at that time, and would you be able to disclose the design and timelines at the meeting? That's the first question. And then second question, just broadly on the TCEs, you've mentioned the potential for differentiation versus either other TCEs in development or just broadly in the spaces of HER2 and PSMA to begin. Do you need to see differentiation in order to move those beyond phase one, or is simply safe and effective good enough at this point with additional differentiation to be established in future studies? Thanks.

Mark Eisner (CMO)

For the HDV question, we are planning, as I added, to disclose more information about the final trial design, the phase three designs. You'll be able to see that at the investor event around AASLD. More coming there. In terms of timelines, right now, we're not disclosing additional information about that, and we will look to do that when we have full clarity on timelines. In terms of the TCE question, Marianne, would you like me to take that one?

Marianne De Backer (CEO)

Sure. Absolutely.

Mark Eisner (CMO)

Okay. So your question is around what we would need to see to move these programs forward for HER2 and PSMA. To be honest, that's really something that is going to be a data-driven decision. I think we are looking at this very early stage, of course, to look at proof of concept. And the preliminary monotherapy data that we'll present in quarter one, I think, will start to give a picture of what the programs look like. In terms of the more specific answer to your question, I don't think we're quite ready to opine on that yet, but we will look to provide more color on that at a future time point.

Michael Ulz (Executive Director at Biotechnology Equity Research)

Perfect. Thanks for taking our questions.

Operator (participant)

We'll go next to Patrick Trucchio at H.C. Wainwright.

Patrick Trucchio (Managing Director of Equity Research)

Thanks. Good afternoon. Just a couple of follow-up questions for me. First, in the HDV program, can you discuss more how the combination of Elebsiran and Tobevibart would be expected to be differentiated from Bulevirtide, including at higher doses, and the level of confidence that patients would maintain ALT normalization and virologic response to switch from Bulevirtide to the combination treatment regimen based on what we've seen in the clinical data so far?

And then separately, with the HBV program, regarding the 20% functional cure rate without interferon and 30% functional cure rate with interferon, can you tell us if these rates would be anticipated in the all comers, or is it in the low S-antigen at baseline patients? And if we look ahead to a potential phase three pivotal program, can you talk about or tell us more if you're thinking about maybe stratifying based on S-antigen at baseline? Would it make sense to explore this combination in patients with low S-antigen at baseline?

Mark Eisner (CMO)

Okay. So your first question about HDV, the first part of that was about the combination of Tobevibart and Elebsiran versus Bulevirtide. With the two-milligram approved dose, we do expect to get much higher levels of target not detected based on our data we presented at EASL than Bulevirtide, which is 12% at 48 weeks. Your question about the higher dose, I mean, that dose isn't approved anywhere. But even so, I think the level of TND efficacy that we expect to have should be superior to Bulevirtide, just thinking about what we're likely to see.

In terms of level of confidence from Bulevirtide switch, yeah, I mean, in terms of the patient population who's been on Bulevirtide, who is likely to enter such a trial or in a clinical practice, we would expect to be much higher in terms of our virologic response with our combination and continued treatment with Bulevirtide. In terms of your HBV question, fundamentally, I think your question's around, is this going to be an all-comers versus a stratified population based on baseline surface antigen? I guess I just ask you to stay tuned for the data, and those questions should become much clearer at the March presentation at the liver meeting.

Eric Joseph (VP and Equity Research Analyst)

Great. Thank you so much.

Operator (participant)

This concludes the Q&A session of the call. Thank you for participating. I'll turn the call back over to Rich.

Richard Lepke (Senior Director of Investor Relations)

Thank you all for your interest in Vir and for participating in today's earnings call. We appreciate your continued support and look forward to providing further updates on our progress in the future. Audra, this concludes our call. Thank you. You may close the call.

Operator (participant)

Thank you. That does conclude today's conference call. Thank you for your participation. You may now disconnect.