Hello. Welcome to Vir Biotechnology's Second Quarter 2025 Financial Results and Corporate Update Call. As a reminder, this conference call is being recorded. [Operator Instructions] I will now turn the call over to Rich Lepke, Senior Director, Investor Relations. You may begin Mr. Lepke.

Thank you, and good afternoon. With me today are Dr. Marianne De Backer, our Chief Executive Officer; Dr. Mark Eisner, our Chief Medical Officer; Jason O'Byrne, our Chief Financial Officer; and Dr. Mika Derynck, our Executive Vice President of Oncology, who will be available during the Q&A session. 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. Please go ahead.

Good afternoon, everyone, and thank you for joining us for Vir Biotechnology's Second Quarter 2025 Earnings Call. I'm excited to share our progress with you today as we've achieved several important milestones across our pipeline this quarter. The past few months have been remarkably productive with significant advances in both our hepatitis delta and oncology program. These achievements reflect our team's commitment to our mission of powering the immune system to transform patients' lives and I'm grateful for both their dedication and your continued interest in our journey. Our key accomplishments this quarter demonstrate our continued momentum across our pipeline. First, we've made significant progress in our ECLIPSE registrational program for hepatitis delta. Following our first quarter milestone of enrolling the first patient in ECLIPSE 1, we have now recently enrolled the first patients in both ECLIPSE 2 and ECLIPSE 3 and all 3 registrational studies are now actively recruiting patients globally. Second, we've successfully initiated our Phase I study for VIR-5525, our EGFR-targeted T cell engager, marking our third clinical stage T cell engager program. And third, we've continued to make progress in our existing T cell engager programs with both VIR-5818 and VIR-5500 advancing in their respective Phase I studies. We also received IND clearance to evaluate VIR-5500 in earlier lines of prostate cancer treatment in combination with androgen receptor pathway inhibitors. Let me now elaborate on our chronic hepatitis delta program, which represents a significant near-term commercial opportunity for Vir Bio. The ECLIPSE registrational program is designed to address different patient populations across the treatment continuum, from treatment-naive patients to those who have not adequately responded to existing therapies. This comprehensive approach builds on our compelling SOLSTICE Phase II data, which demonstrated impressive virological responses with our combination therapy of tobevibart plus elebsiran. The hepatitis delta opportunity…

Thank you, Marianne. We've made significant progress across both our infectious disease and oncology portfolios during the second quarter, and I'll walk you through the key developments. I'm excited to report substantial progress in our ECLIPSE registrational program for hepatitis delta. Building on our first quarter milestone of enrolling the first patient in ECLIPSE 1, we have now just recently enrolled the first patients in both ECLIPSE 2 and ECLIPSE 3, and all 3 studies are now actively recruiting patients globally. We remain on track with our overall development time line with primary completion for ECLIPSE 1 expected by December 2026. Let me now provide details on each study. ECLIPSE 1 is designed to evaluate our combination therapy in regions where bulevirtide is not available or has limited use, including the United States. The study will enroll 120 participants randomized 2:1 to receive either our combination therapy or deferred treatment. The primary endpoint is a composite endpoint of HDV RNA target not detected and ALT normalization at week 48. ECLIPSE II will enroll approximately 150 patients randomized 2:1 and evaluate switching to our combination therapy in patients who have not adequately responded to bulevirtide. This study addresses an important unmet need for patients who have limited options after bulevirtide treatment. ECLIPSE 2 has a 24-week primary endpoint of HDV RNA target not detected, which could potentially provide a readout at a similar time point as ECLIPSE 1. ECLIPSE 3 is our Phase IIb study that will enroll approximately 100 patients comparing our combination therapy to bulevirtide and bulevirtide-naive patients. This head-to-head comparison will provide important data to support access and reimbursement discussions. Together, ECLIPSE 1 and 2 are designed to form the backbone of our regulatory submissions in the U.S. and Europe. This comprehensive approach addresses different patient populations and…

Thank you, Jason. This concludes our prepared remarks, and we will now start the Q&A session. Please limit your questions to 2 per person so that we can get to all of our covering analysts. I'll turn it over to you, operator.

[Operator Instructions] Our first question comes from the line of Mike Ulz from Morgan Stanley.

It's Avi Novick on the line for Mike. Yes. So I guess just on HDV, could you perhaps give us a little bit of an enrollment update on the ECLIPSE programs, particularly for ECLIPSE 1? And then this might be a little bit premature, but I guess, as we think about the TAM in HDV, can you tell us about any sort of prep work or thoughts on how to further identify the prevalent patient population?

Thank you, Avi. I'll ask Mark to comment on that.

Yes. Thanks for the question. So yes, we're really excited that we now have all 3 ECLIPSE registrational studies up and running with enrolling patients. Enrollment in ECLIPSE 1 is going very well. We're not in a position yet to provide more specific updates, but we have said before, we anticipate completing enrollment by the end of this year with a completion date for the primary endpoint at the end of '26. ECLIPSE 2 and ECLIPSE 3, we've just gotten up and running, so a little premature to make statements about how enrollment is going. But so far, we're working really hard, executing really well, really excited about the investigator excitement and responsiveness for these programs. In terms of the work on prevalent HDV, I mean, I think what you're alluding to is it is a challenge estimating the epidemiology of HDV because, particularly in the U.S., because there's no approved therapy, there's no reflex testing, which is automatic testing in HDV-positive patients for delta. So it's a little bit unclear right now how many patients there may be. We're estimating about 61,000 who are viremic in the U.S. right now. We suspect that's probably an underestimate. Once we get to the finish line and launch our therapy, which would be very attractive for patients, that there'll be more education, screening and effort to find patients.

Our next question comes from the line of Gena Wang from Barclays.

I have 2. One is for ECLIPSE and the other is for 5525. So regarding ECLIPSE, if I hear correctly, you said that December 2026 primary completion for ECLIPSE 1. Is it fair to say that you've already enrolled majority of the 120 patients since the study is of 48 weeks? My second question is regarding 5525. I saw your starting dose is only 3 micrograms per kilogram. Since you expect similar safety profile for 5525 versus the other 2 targets, why not start at the higher dose? Also, will you test both like once-weekly dosing and once every [Technical Difficulty] dosing?

Thank you, Gena. It was a little bit difficult to hear you, so please correct us if we haven't fully understood the question. On ECLIPSE 1, you were referring to our primary data completion of December 2026 and enrollment. So maybe, Mark, you can comment on that.

Yes. I would say we're not providing specific updates on enrollment, but recall that enrollment in trials always starts off slower and then ramps up as sites are activated, enrolling patients. All I can say is we're really pleased with how we're doing, and we'll provide an update in the future, so stay tuned for that.

Okay. And then as it's related to your question on our EGFR T cell engagers, 5525. So if I understood you correctly, you were asking why not start at a higher dose given what we have learned from our prior programs. Mika, do you want to comment on that?

Sure, sure. Yes. No, thanks for the question. So we are basically starting at a dose that is standard by regulatory authorities for T cell engagers, which is using the label dose. And so each molecule has --they're in the same range, but they have their own estimated label dose. And we just have to do our start dose from there. But we do have a lot of confidence that we have the potential for a wide therapeutic index for 5525 in that this is a universal platform in that the masks are identical for 5500 and 5818 and as are the protease linkers. And so in terms of if you look at the preclinical data for 5500 and 5818, both of those programs have shown really robust potential for a wide therapeutic margin and safety profile. And similar, when we make those comparisons preclinically with 5525, again, we see this very encouraging and promising potential for a wide therapeutic margin looking at safety studies, toxicology studies in animals and so forth. So we do believe that there is this wide potential for this molecule, and we'll be able to accelerate this program much faster given the learnings that we've had from both the 2 previous HER2 and PSMA programs. And as far as testing other dosing regimens, just as standard for the IND studies, we are required to study this initially weekly, but we are certainly -- again, the preclinical data does suggest that we would have a potentially good half-life to be able to dose less frequently q-3-week and potentially later.

Our next question comes from the line of Paul Choi from Goldman Sachs.

This is [ Daniel ] on for Paul. We're wondering if there are going to be additional data cuts from the Phase II SOLSTICE study for the HDV program. And we're also wondering for the next data cut for VIR-5500 for PSMA. Are you going to share PFS data or radiology-based measurements in addition to PSA biomarkers?

So thanks for the question. We do plan to provide an update on the SOLSTICE study, the complete 48-week data by the end of the year. So stay tuned for that. For 5500 next data cut, we haven't provided guidance about exactly when that will be. We do want it to be a very meaningful update. We're currently escalating in Q1, q-3-weeks, and it's going very, very well. In terms of what specific data we'll present, also we haven't provided guidance there. But we will try to provide clear evidence of dose response, depth and durability, the PSA responses, and other biomarkers and other measures. So we'll provide more detail on what to expect at a later date.

Our next question comes from the line of Alec Stranahan from Bank of America.

This is [ Matthew ] on for Alec. Maybe first one from us on ECLIPSE. Can you just remind us whether both ECLIPSE 1 and 2 data is needed for registration in the U.S.? And then maybe on the TCE program, would you expect the next updates for 5818 and 5500 to be sort of the go/no-go point for these studies? And would we expect a final decision on dosing frequency for those programs as well?

So thank you for those questions. The first question is around whether we expect or need both ECLIPSE 1 and ECLIPSE 2 for the first registrational filing. That is our base case. That said, we have other scenarios that we could consider. If, for example, ECLIPSE 1 completed much ahead of ECLIPSE 2, we could consider following that along with SOLSTICE for an initial approval in the U.S. That would have to depend on the strength of the data, discussions with regulators, including FDA, having breakthrough therapy designation status in the U.S. and PRIME in Europe does allow us to have those conversations, but it's going to depend on the relative speed of enrollment of the trials. And as a reminder, ECLIPSE 2, although it started a little bit later, it's a 24 as opposed to 48-week program point, so it could complete around the same time as ECLIPSE 1, but it's a little early to say for sure. I think your next question was around data updates for the 5818 and 5500 and what to expect there. We haven't made a final decision about exactly what those updates will look like, whether they'll be together or whether they'll be separate. For 5818, we have said that we are --we've completed monotherapy dose escalation, but we're continuing with escalation with pembrolizumab, and we're currently analyzing all of the data, PK/PD, efficacy, looking at dose and schedule and making --we'll be making decisions about next steps of development. So we would expect to provide that at an upcoming time. And for 5500, again, it's a little early to be definitive about what we'll provide. But as I was saying before, we want to be able to provide a meaningful update where you get a strong sense of depth, durability, dose response, other key pieces of information.

Our next question comes from the line of Phil Nadeau for TD Cowen.

Congrats on the progress. First one on ECLIPSE 2. I believe that you are defining the enrollment criteria for that of patients who are on Hepcludex who don't achieve HDV RNA less than 500 international units per ml. Can you talk about how you're identifying those patients and how easy you expect it to be to recruit that trial? That's the first question. And then second, just in terms of updated data for 5518 in particular, it sounds like the monotherapy dose escalation is completed. Are there any thoughts to releasing that monotherapy data once you're done analyzing it, or will you hold that data to have the combo data as well?

Sure. So thanks for your questions. On the first question for ECLIPSE 2, correct. These are patients who have been on bulevirtide for at least 6 months, are still viremic and they are then eligible, if they meet other criteria as well, for enrollment. Actually identification of these patients is relatively straightforward because the investigators all know which of their patients are on bulevirtide. So they can then test them to see what their level of viremia is, and then if they're eligible, they can be enrolled. So identifying those patients is relatively straightforward. And then I think we randomized them, of course, to switch to tobevibart and elebsiran versus continued bulevirtide with the 24-week primary endpoint of HDV target-not-detected virologic endpoint. I think it's a very appealing trial because patients who are still viremic on bulevirtide, then we'll have the opportunity to test it on our regimen where we've been able to show approximately 2/3 of patients are achieving complete viral suppression. For your question, about 5518, what's the next data release look like, is it going to be monotherapy, or are we going to hold for combination. Yes, we really haven't decided. We're looking at the totality of the data now. We're escalating in combination with pembrolizumab. That's going very well. So we'll just have to make a decision about what would be the most appropriate update and what would be the most appropriate setting for that update.

Our next question comes from the line of Roanna Ruiz from Leerink Partners.

Yes. This is Mazi for Roanna. Just one on the hepatitis space from us. So how do you view the evolving competitive landscape in the chronic hepatitis delta space? And then what advantages do you see for your combination approach in terms of market positioning?

Sure. So in terms of the competitive landscape, a couple of comments. One is Gilead apparently has or is refiling bulevirtide, Hepcludex, for the U.S. And we don't know about the timing specifically. But assuming that they would get approved sometime in 2026, we actually think that would be a big positive for us because having Gilead going out and starting that education of physicians and health care providers and promoting testing for HDV would help prepare the way for Vir and our launch. So we would welcome that opportunity. And particularly since we have a drug regimen with our combo of tobevibart and elebsiran, we're achieving high levels of target not detected at week 48, and we've shown we expect to have above 60%. All told, that compares to 12% with bulevirtide. So we think we have a very compelling clinical case to make there. In terms of the combo approach, I think we're very excited about it because we're suppressing the virus to undetectable in the majority of patients. It's clearly better than our monotherapy with tobevibart, our antibody. So we think we can beat other monoclonal antibodies as well in terms of viral suppression. We also can suppress hepatitis B surface antigen by 3 logs, which is multiple logs greater than a monoclonal antibody alone. And recall that you need the HBV surface antigen for the delta virus to replicate itself. So we're starving the delta virus of what it needs for its viral life cycle. So I think all in all, we feel like we have a best-in-disease, best-in- class approach, and we're executing the trials well, and we're looking forward to helping as many patients as possible.

Thank you, Mark. I would just add that, as Mark mentioned, we have a profile that really has the potential to set a new standard of care. And obviously, with more entrants entering to the market, it's also really a testament to the unmet need that we are seeing in hepatitis delta and obviously, the commercial opportunity that it represents.

Yes, that's great, Marianne, really great comment. And the other point would be that with the monthly administration, we feel we're going to have a very, very superior convenience to bulevirtide, which is daily and other competitors are more likely going to be weekly with an antibody. So we think from a convenience and adherence point of view, we're feeling very good about where we're landing there.

Our next question comes from the line of Sean McCutcheon from Raymond James.

Just a couple on 5500 for us. Can you speak to the patients you've been enrolling since the payer update for 5500? Obviously, a lot of focus on the post-PSMA radioligand setting. Are you prioritizing this patient population? And should we anticipate a meaningful look at activity in that patient population at the next update? And then additionally, can you provide your view on the relative importance of less frequent dosing for 5500 and maybe perhaps speak to the biologic rationale for less frequent dosing or dosing holiday as it relates to T cell exhaustion for T cell engagers?

Yes. So thank you for that question. So the types of patients that we are currently enrolling is sort of a standard first-in-human Phase I where they must have exhausted all standard of care. Now having said that, where we are currently open right now is in Australia and in Europe. And in those settings, there aren't as many -- there are some, but there aren't as many patients who've had prior radioligands. So we don't have quite yet a lot of data in that patient setting. But we do plan on opening in the U.S., and we do plan on trying to generate that data in late-line setting. But we're also excited about going into the early line setting as well. We've recently, as Mark had mentioned, opened --have IND clearance to combine with androgen receptor pathway inhibitors in the frontline setting in a very early metastatic hormone-sensitive prostate cancer setting as well as a biochemical recurrence setting. And so that early line setting, I think, will be quite meaningful for something like this with our current toxicity profile. And then that also relates to the less frequent dosing. So we have demonstrated with the HER2 program that we can dose less frequently at q-3-week and see a similar safety and efficacy profile thus far. We are currently encouraged with what we're seeing. We're now dosing at q-3-week in the 5500 program as well. And what we've learned from the HER2 program, at least is that we don't see resensitization during that week holiday. So I think this is an important factor in T cell engager space is that most people have to step up dosing, everybody has to step up dose. And reason to get that is to desensitize so that you can get to much higher doses. But then once you get up there, what's really next important is to have a reasonable half-life that allows you to then do less frequent dosing and then you don't have that resensitization. And that's been proven out with the HER2 program. And similarly, efficacy, we've seen at the same doses, either q- week or q-3-week efficacy in the HER2 program. So we think that this bodes well for the 5500 program. It has a slightly longer half-life than the HER2 program. And then this is going to be so important in the early line setting where that [indiscernible] where dosing strategies are often for months, if not years, and to have a much less frequent dosing is going to be a key differentiator for our program.

Our next question comes from the line of Patrick Trucchio from H.C. Wainwright.

Just a couple of follow-ups from us. Just a clarification question on whether the U.S. regulatory filing could proceed based on ECLIPSE 1 and SOLSTICE or is the base case still for both ECLIPSE 1 and 2? And then just with ECLIPSE 3, this is the head-to- head comparison versus bulevirtide. Can you talk about what you would need to see in that program? And is that primarily for the European or ex-U.S. reimbursement? And what would you need to see to give confidence in that you can get reimbursement in that program internationally? And then just separately on the PRO-XTEN, I'm just wondering, given this unique opportunity in KRAS- mutant tumors, particularly in CRC and lung, how are you designing the 5525 program to ensure you capture that population?

Okay. So a couple of quick questions on delta. The first one has to do with the U.S. regulatory filing and what we expect we need. You're right. We do expect ECLIPSE 1 and 2 to be the base case for filing. I do think that they're -- if they finish in the similar time frame, which we expect, that would be ideal, and we would use both of those as the core part of the filing for the U.S. If for some reason ECLIPSE 1 were to finish substantially ahead, we could talk to FDA about whether ECLIPSE 1 and SOLSTICE could comprise the initial filing package and leverage our breakthrough therapy designation in the U.S. and by our PRIME designation in Europe to have those discussions. So those do remain potential options down the road. For ECLIPSE 3, yes, remind everyone it's a head-to-head study of tobevibart and elebsiran versus bulevirtide and bulevirtide-naive patients. And we are looking at virologic endpoint target not detected at week 48 compared to bulevirtide. Bulevirtide is expected to be about 12%, and we expect to be north of 60% for our combination. So we are looking for superiority based on the virologic endpoint. The primary driver for the study, rationale for the study is to enable European payer HTA negotiations around price and access. It will comprise data that will be useful for all of our filings globally on the safety data side and also head-to-head data are always helpful. But primarily, we are looking at that as a payer and access-oriented study.

Yes. So I can take on the PRO-XTEN question. So our 5525 Phase I study as standard -- again, we have to enroll patients who must have exhausted all standard-of-care. And that includes any KRAS inhibitors that are approved in either lung cancer or any other space. And so we do anticipate that we will be able to enroll these patients. But I think a really very important point is that the T cell engager, our masked T cell engager is a different mechanism of action altogether. It is redirecting your immune cells to kill any tumor cells expressing EGFR. And by doing so, it uses it as an address. And so it's regardless of the downstream mutations that are there. So it should work in tumor types that are driven by KRAS as well as any other mutation, even EGFR mutation as well as a multitude of other mutations that happen in lung cancer. So I think this is a unique modality that could either go anywhere in the journey of a patient with lung cancer. It potentially could combine with a KRAS inhibitor, again, because of that differential mechanism of action.

Our final question comes from the line of Joseph Stringer from Needham & Company.

The ECLIPSE 1 trial has a 12-week deferred treatment period versus 24 weeks for a Phase III competitor. So can you remind us the rationale for the 12 weeks here? And what's the potential impact on trial success or potential differentiation?

Yes. So good question. So ECLIPSE 1 randomizes us to our regimen of tobevibart and elebsiran versus a 12-week deferred treatment period. And the primary endpoint is actually 48 weeks for our combination versus 12 weeks in the deferred treatment arm. The rationale for that is that delta virus without any treatment, we expect essentially 0 patients to spontaneously clear the delta virus. So a 12-week deferred treatment arm is really acceptable because it's going to predict almost perfectly what's going to happen in week 48. We have agreement from FDA and EMA on that point. 12 weeks is, in our mind, better than 24 weeks operationally because it's a more appealing design for patients because they don't have a long time to wait if they get randomized to the deferred treatment arm to cross over to the active treatment arm. So we think it's a very patient-friendly design from that standpoint. From a probability of success, I would say 12 versus 24 weeks is essentially the same because in neither time period do we expect spontaneous delta conversions to complete suppression in either setting. So I think it's 12 weeks is very patient friendly. I think in terms of probability of success, it's also very attractive.

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

Thank you, operator. Thank you all for your continued support and for joining us today. We look forward to updating you on our progress in the coming months. Operator, you may end the call.