speaker
Operator
Conference Operator

Good day and thank you for standing by. Welcome to the Arbutus Biopharma 2024 First Quarter Financial Results and Corporate Update Conference Call. At this time, all participants are in a listen-only mode. After the speaker's presentation, there will be a question and answer session. To ask a question during the session, you will need to press star 1-1 on your telephone. You will then hear an automated message advising your hand is raised. To withdraw your question, please press star 1-1 again. Please be advised that today's conference is being recorded. I would now like to hand the conference over to your first speaker today, Lisa Capparelli, Vice President of Investor Relations. Please go ahead. Thank you, Andrea.

speaker
Lisa Capparelli
Vice President, Investor Relations

Good morning, everyone, and thank you for joining Arbutus' first quarter 2024 financial results and corporate update call. Joining me today from the Arbutus executive team are Mike McElhall, Interim President and Chief Executive Officer, Dr. Karen Sims, Chief Medical Officer, David Hastings, Chief Financial Officer, and Dr. Mike Sophia, Chief Scientific Officer. Mike McElhall will begin with a corporate update, followed by Karen, who will review our ongoing clinical programs. Dave will then provide a review of the company's first quarter 2024 financial results. After our prepared remarks, we will open the call for Q&A. Before we begin, I'd like to remind you that some of the statements made during the call today are forward-looking statements which are subject to a number of risks and uncertainties that may cause our actual results to differ materially, including those described in our annual report on Form 10-K, our quarterly report on Form 10-Q, which will be filed today, and from time to time in our other documents filed with the SEC. With that, I'll turn the call over to Mike McElhall. Mike?

speaker
Mike McElhall
Interim President and Chief Executive Officer

Thanks, Lisa. Good morning, everyone, and thank you for joining us today. This morning, we issued two press releases, one announcing the end of year retirement of our co-founder and chief scientific officer, Dr. Mike Sophia, and one with our first quarter of 2024 financials and a corporate update. I want to pass the call to Mike Sophia to address his retirement. Mike?

speaker
Dr. Mike Sophia
Chief Scientific Officer

Thanks, Mike, and good morning, everyone. Today we announce my decision to retire as chief scientific officer at Arbutus, effective the end of this year. I will continue in my full capacity as CSO until that time. Since co-founding Arbutus more than 10 years ago, the company has made incredible strides in its research and clinical efforts. We have built an organization of dedicated individuals who are passionate about our mission to cure HPV. I continue to believe that Arbutus is on the correct path to developing a functional cure for the millions of patients living with HPV. My lifelong goal has been to discover medicines that improve patients' lives. Over my 38-year career in pharma and biotech, one of my great successes was the discovery and development of sofosbuvir, the backbone of curative therapies for hepatitis C, which has already cured millions of patients globally. Learnings from the HCV story spurred me towards finding a cure for the more challenging problem, HPV. This led to the founding of Arbutus, where we have been able to build a world-class team uniquely positioned to potentially transform the HPV treatment landscape with drug candidates like Mduceran and AB101. Throughout my more than 10 years at Arbutus, I have enjoyed tackling the many challenges that drug discovery and development brings, collaborating with my colleagues, and mentoring many of the scientists here. I am confident this passionate and dedicated team will continue to do great things. I have great pride in what we have been able to accomplish at Arbutus. I look forward to following the future successes as the company advances its mission in finding a cure for HPV. Thank you, and back to Mike.

speaker
Mike McElhall
Interim President and Chief Executive Officer

Thanks, Mike, and thanks for everything you've done for Arbutus and our shareholders. I'm sure I speak for all employees when I say it's been an honor to work with you. We all wish you the best in your retirement. Now on to our Q1 financial and corporate update press release that we issued today. announcing significant achievements made in advancing our pipeline in pursuit of developing a functional cure for patients with HPV and driving value for our company. We believe our two proprietary clinical assets in HPV, Imduceran, our RNAi therapeutic, and AB101, our oral small molecule PD-L1 checkpoint inhibitor, have the potential to deliver on our three-pronged approach to functionally cure chronic HPV, which involves reducing surface antigen, suppressing HPV DNA, and boosting the immune system. While Induceran has shown activity in all three of these components in clinical trials conducted to date, we know a combination of agents are necessary to cure this challenging disease. I'll turn the call over to Karen shortly to walk through preliminary data from our Phase 1A-1B clinical trial with AB101 and to provide an overview of our third Phase 2A clinical trial that is evaluating the combination of Induceran and drivalumab, a PD-L1 monoclonal antibody, which has begun screening patients. Currently, we have two Phase IIa combination clinical trials, the AB729201 trial, which includes the addition of interferon, and the AB729202 trial, which includes the addition of barinthus biotherapeutics immunotherapeutic VTP300. These trials are intended to provide data on the safety and efficacy of imduceran as a cornerstone therapy and to help us identify an optimal combination treatment that we can advance into a later stage clinical trial. This quarter, we will report end-of-treatment data from these two Phase IIa trials with Imdusiran, which could potentially include patients who achieve undetectable surface antigen. As we've previously stated, achieving undetectable surface antigen in either of these two Phase IIa clinical trials would be an important validation of Imdusiran's role as a cornerstone in potentially achieving a functional cure for patients with chronic HPV. We are happy to report that two abstracts, including data from these Phase IIa clinical trials, were accepted for presentation at the EASL Congress, which takes place in early June in Milan, Italy. We will provide more details on those abstracts at a later date. With that, I'll turn the call over to Karen to provide an overview of the AB729203 clinical trial and to discuss the AB101 Phase I preliminary data. I'll come back at the end of the team's prepared remarks to provide an update on our LNP litigation before we move into Q&A. Karen?

speaker
Dr. Karen Sims
Chief Medical Officer

Thanks, Mike, and good morning, everyone. As Mike mentioned, our approach to developing a functional cure for patients with chronic hepatitis B involves reducing surface antigen, suppressing HPV DNA, and boosting the immune system. In our clinical trials conducted to date, Induceran has been shown to reduce HPV DNA in untreated patients and reduced surface antigen when given both with and without ongoing standard of care nuke therapy. In addition, evidence of HPV-specific T-cell reawakening has been observed in some patients undergoing treatment with imdustoran. To further boost the immune system, we designed our phase 2A trials to evaluate imdustoran in combination with one of three immunomodulatory approaches, interferon, a therapeutic vaccine, or a checkpoint inhibitor targeting the PD-1, PD-L1 axis. Our two ongoing Phase 2A clinical trials, AB729201 and AB729202, are evaluating Induceran in combination with interferon and in combination with a therapeutic vaccine, respectively. As Mike said, both of these Phase 2A trials are on track to report end-of-treatment data at the Easel Congress in June. Note that we also amended the AB729202 trial to evaluate the addition of the PD-1 checkpoint inhibitor antibody nivolumab, to the Induceran and BTP300 combination. We expect preliminary end of treatment data from that cohort in the second half of this year. Today, we announced that we have initiated patient screening in our third Phase IIa clinical trial, AB729203, which is evaluating Induceran in combination with Dervalumab, an anti-PD-L1 monoclonal antibody. While all of these Phase IIa trials are geared towards finding the right immune modulator to combine with Induceran, The AB729203 trial with Dervalumab is specifically intended to evaluate how we can use checkpoint inhibition in combination with Induceran to boost HPV-specific immune responses. This trial will inform upcoming combinations with our proprietary oral small molecule PD-L1 checkpoint inhibitor, AB101. With that backdrop, I'd like to provide more information regarding the AB729203 trial design. AB 179203 is an open-label, multi-center, phase 2A clinical trial evaluating the safety, tolerability, antiviral, and HPV-specific immunologic activity of imduceran and ongoing Duke therapy in combination with Dervalumab, an approved anti-PD-L1 monoclonal antibody in patients with chronic hepatitis B. We intend to enroll 30 virologically suppressed patients into three separate cohorts. All patients will receive 60 milligrams of Induceran every eight weeks with their ongoing nuke therapy for 48 weeks and will receive two doses of Dervalumab at pre-specified times during the Induceran treatment period that will differ by cohort. After completion of treatment, all patients will be assessed for eligibility to discontinue nuke therapy and will be followed for an additional 24 to 48 weeks. The endpoints for this clinical trial include safety, and changes in surface antigen from baseline during the treatment and follow-up period. This trial allows us to explore the optimal timing of checkpoint inhibitor dosing in the context of surface antigen reduction during ongoing abducerant treatment. Now moving on to our proprietary oral small molecule checkpoint inhibitor, AB101, that is differentiated from monoclonal antibodies, such as dervalumab and nivolumab, in the following ways based on our preclinical testing. First, AB101 is liver-centric, meaning it preferentially traffics to the liver and has a high liver-to-plasma ratio, thus minimizing systemic exposure and reducing the chance of immune-related adverse events seen with monoclonal antibodies. Second, AB101 has typical small-molecule pharmacokinetics and therefore a much shorter duration of effects than long-acting antibodies, thus allowing for the potential to modify the dose or dosing interval to maximize effects or to stop dosing to quickly mitigate any safety concerns. Third, AB101 acts through a novel mechanism of action, differentiated from antibodies. It binds to PD-L1 on the surface of cells, causing dimerization and internalization of the PD-L1 protein, followed by degradation within hours. Washing out of the drug results in full reconstitution of PD-L1 on the cell surface and restoration of PD-L1 function within days. unlike antibody therapy, where the duration of receptor occupancy and PD effect is maintained for weeks with no ways to reverse it. It is for these reasons that we are excited about the potential of AB101 and HBV and are advancing our AB101 clinical program, which is currently evaluating AB101 in a double-blind, randomized, placebo-controlled Phase 1A, 1B clinical trial known as AB101-001. This trial is designed to investigate the safety, tolerability, pharmacokinetics, and pharmacodynamics of AB101. The trial consists of three parts, starting with single and multiple ascending doses in healthy subjects, and culminating with multiple doses in patients with chronic HPV. In part one, which is the single ascending dose portion of the trial, we have enrolled four sequential cohorts of eight healthy subjects each to date. Within a cohort, six subjects received AB101 and two subjects received placebo. And after review of safety, PK and PD data, AB101 dose levels were increased in each subsequent cohort up to 25 milligrams. The data from Part 1 showed that AB101 is generally well tolerated with evidence of dose-dependent receptor occupancy. In the 25 milligram cohort, five of the six subjects had test samples that were evaluable for receptor occupancy. and all five of these subjects showed evidence of PD-L1 receptor occupancy between 50 and 100%, indicating that AB101 is interacting with its intended target. One subject in this cohort was excluded from the PD evaluation as their samples could not be analyzed. We are now in part two of this trial, where cohorts of healthy subjects are receiving multiple ascending doses of AB101. Our goal is to move as quickly as possible into part three, which will enroll patients with chronic hepatitis B. We anticipate announcing preliminary data from Part 2, the multiple ascending dose portion of this trial in healthy subjects, in the second half of this year. We believe that the immune checkpoint pathway plays an important role in HPV-specific immune tolerance and in T cell activation, and the addition of a checkpoint inhibitor in combination with Induceran could potentially further enhance HPV-specific immune responses. With that, I'll turn the call over to Dave Hastings for a brief financial update. Dave?

speaker
David Hastings
Chief Financial Officer

Thanks, Karen, and good morning, everybody. We ended the first quarter of 2024 with approximately $138 million of cash, cash equivalents and investments, compared to approximately $132 million as of December 31, 2023. During the quarter ended March 31, 2024, we received $21.8 million of net proceeds from the issuance of common shares under Arbutus' At-the-Market Offering Program. These cash inflows were offset by $19.3 million of cash used in operations. We still expect our 2024 net cash burn to range from between $63 to $67 million, excluding any proceeds from our ATM program. In April 2024, we received an additional $22.4 million in net proceeds from sales under our ATM. And now importantly, we believe our cash runway is sufficient to fund our operations through the second quarter of 2026. So in closing, we have a strong financial position to advance our mission of developing our HBV assets to provide a functional cure for chronic HBV. With that, I'll turn the call back to Mike.

speaker
Mike McElhall
Interim President and Chief Executive Officer

Thanks, Dave. With today's update, we have achieved most of our first half of 2024 key milestones, including reporting preliminary data from the AB101 phase 1A, 1B clinical trial and initiating the phase 2A clinical trial with imducerin and drivalumab. We look forward to reporting the data from the AB729201 and 202 phase 2A clinical trials at EASL in June. In the second half of this year, we anticipate preliminary end of treatment data from the nivolumab arm of the 202 trial and preliminary multiple ascending dose data from the healthy subjects in the AB 101-001 trial. 2024 is off to a strong start, and it wouldn't be possible without the dedication of my Arbutus colleagues. I would like to take this opportunity to thank all of them for their hard work to advance our pipeline. Before turning the call over to Q&A, I'd like to provide a brief update on the ongoing patent infringement lawsuit, specifically the lawsuit against Moderna. As you may recall, on February 8th of this year, there was a claim construction hearing also commonly referred to as the Markman hearing, where the court heard each party's interpretation of the construction of claims in the disputed patents. The court issued its order on April 3rd in which it agreed with our position on most of the disputed claim terms. This is another important step in the ongoing litigation process and provides clarity on the interpretation of key terms and the scope of the claims. I refer you to the press release that we issued on April 4th, which is available on our website and summarizes the claims related to the three patents that were presented at the Markman hearing and the court's position on each claim. While this is important for us, we cannot further comment or elaborate on what is in the press release, but we suggest you review the judge's opinion, which is also available on our website. In his opinion, the judge provides an overview of the disputed aspects of each claim and each party's position, as well as the evidence that was used to inform his decision-making process. The litigation process continues to move forward. Fact discovery is ongoing and next steps include expert reports and depositions. The court has set April 21st, 2025 as the trial date for this case. That date is subject to change. The Pfizer BioNTech lawsuit is ongoing and a date for the claim construction hearing for that case has not yet been set. We will continue to protect and defend our intellectual property, including our LNP delivery technology. All of our scientists take great pride in the intellectual property they develop, which takes great effort, time, resources, and expense. Operator, we're now ready to open the call for Q&A.

speaker
Operator
Conference Operator

Thank you. At this time, we will conduct the question and answer session. As a reminder, to ask a question, you will need to press star 11 on your telephone and wait for your name to be announced. To withdraw your question, please press star 11 again. Please stand by while we compile the Q&A roster. Our first question comes from Dennis Ding with Jefferies. Please go ahead.

speaker
Dennis Ding
Analyst, Jefferies LLC

Hi. Good morning. Thanks for taking our questions. Two, if I may, on the pipeline. You guys have a few phase two trials with, you know, a lot of different combinations going on. But how about when do you think we can get any functional cure signals? And is that a 2025 type of event? Or can we get some data later this year? And then number two, you know, I appreciate you starting a new phase two. with DERVA, but I'm just curious, how much more data do you think you'll need from, you know, your hepatitis B trials before you can start a phase three? I'm just wondering what is the gating factor here? Is it waiting for AB101 to show some combo data, or is it data from the new DERVA study, which is, you know, essentially a one-year treatment and a one-year follow-up? So I'm just wondering what the gating factor is there.

speaker
Mike McElhall
Interim President and Chief Executive Officer

Thank you. Good morning, Dennis. Thanks for the question. So, Karen, do you want to handle Dennis' first question on functional cure? Yeah, sure, absolutely.

speaker
Dr. Karen Sims
Chief Medical Officer

So, Dennis, as you know, as you just stated, these trials do take some time, including the treatment period and the extended follow-up period, and as you know, functional cure signals can't be assessed until subjects are at least six months off of all treatment. So that is ongoing in both of our phase two studies at the moment, both the 201 interferon study and the 202 study in combination with, for instance, this VTP 300. So, you know, as the data comes in and as we are able to compile that data into a meaningful data release with sufficient number of subjects, you know, we'll certainly share that data when we can. So I can't give any additional guidance just to say that the trials are ongoing and, you know, we'll present the data as it becomes available.

speaker
Mike McElhall
Interim President and Chief Executive Officer

Okay. And then on to the second question was in regards to the Valumab and when we might be able to start a follow-on trial. I think the answer to that question, Dennis, is it's going to depend on what we see from our existing ongoing studies, right? So, yes, we're starting a new trial, and yes, we think that will be valuable in helping to inform how we think about the addition of AB101 to Induceran. But as Karen just mentioned, we have some trials ongoing, which could, of course, produce interesting data, which could then lead to follow-on studies. So, I don't think that it's a situation where we need to wait until we have the full picture from all of these trials ongoing before we decide what we're going to do to move forward. As you know, the goal here is functional cure. You know, if we can deliver some functional cures in any of the ongoing studies, we will obviously be moving that as quickly as possible into follow-on studies.

speaker
Dennis Ding
Analyst, Jefferies LLC

Got it. Thank you.

speaker
Operator
Conference Operator

Thank you. One moment for our next question. Our next question comes from Ed Arce with H.C. Wainwright. Please go ahead.

speaker
Thomas
Analyst, H.C. Wainwright

Good morning, everyone. This is Thomas. You're asking a couple of questions for Ed. Thank you for taking the questions. So first, perhaps following up with the previous question, just looking forward for an inducer and with the next phase, you know, phase 2B or phase 3 study, would that be expected to evaluate in group serum as a monotherapy or in a combination or perhaps both?

speaker
Dennis Ding
Analyst, Jefferies LLC

So, Thomas, good morning. Thank you.

speaker
Mike McElhall
Interim President and Chief Executive Officer

This is Mike. I think we've always said that we're going to have to think about combination therapy when it comes to curing HPV. We have to hit those three pillars that we talk about frequently. So I think as we think about what a next study might look like, it's definitely going to be a combination study.

speaker
Thomas
Analyst, H.C. Wainwright

Understood. Perhaps one question for Dr. Sims for the new Phase IIa study with the viral map. Can you discuss the rationale behind different dosing interval for the Valumab, and what is the significance to analyze these different dosing intervals?

speaker
Dr. Karen Sims
Chief Medical Officer

Yeah, thanks for the question, Thomas. So, the idea here is evaluating the extent of checkpoint inhibition that's necessary to try to induce that HPV-specific immunity. As I'm sure you're aware, the use of checkpoint inhibitor therapy in oncology is a much different dosing regimen and much different dosing level. So it's very high doses over repeated cycles for weeks to months. And with that comes a safety profile that may not be optimal in patients with chronic hepatitis B. So what we're looking to do is strike the appropriate balance between having a regimen that's safe and well tolerated for these patients with chronic hepatitis B, as well as trying to understand exactly when we need to intervene on the checkpoint inhibitor axis in the context of the surface antigen reduction that we see with induced sarans. So that's the idea behind the trial. Is it best to inhibit the checkpoint axis during the acute decline of surface antigen? Is it best to inhibit after surface antigen has reached a nadir? somewhere in between and, you know, doing that at multiple time points. So that's the idea behind the trial is really to strike that balance between optimal immunomodulatory effects, but maintaining a very good safety profile for this patient population.

speaker
Thomas
Analyst, H.C. Wainwright

Understood. Thank you. And perhaps one last question for AP101. After completing the multi-ascending dose phase of the ongoing phase one study, What's the next step for the program? Would that be looking at a combination study in HPV, or are there other areas that AB101 can have potential in?

speaker
Dr. Karen Sims
Chief Medical Officer

Sure, yes, thanks for the question. Again, just to clarify, so the current study is a three-part study, so single doses in healthy subjects. then multiple doses in healthy subjects, and then we move seamlessly into multiple doses in patients with chronic hepatitis B in combination with nuke therapy. So we need to complete those different portions of the trial to understand the safety profile, the pharmacokinetic profile, the PD profile of AB101 to be able to enter that next phase of studies. But certainly you can imagine after completion of the phase one study, the next goal would be to put it in combination with induced saran in a phase two study as quickly as possible.

speaker
Thomas
Analyst, H.C. Wainwright

Understood. Thank you again for taking all the questions, and looking forward to the easel daily readouts.

speaker
Dennis Ding
Analyst, Jefferies LLC

You're welcome, Thomas. Thank you.

speaker
Operator
Conference Operator

Thank you. One moment for our next question. Our next question comes from Brian Scorny with Baird. Please go ahead.

speaker
Charlie
Analyst, Robert W. Baird & Co.

Hey, guys. Thanks for taking our question, and congratulations and best wishes to Mike. This is Charlie on for Brian. So just a couple from us, just wondering when you're thinking about dosing with AB101, it sounds like so far you've seen good safety data, but just would be curious if you're kind of thinking of 25 mg as a cap in the MAD as well. And then, you know, are you, when you're thinking about this, the Dervalumab trial, have you seen anything from the Nevo combination so far that might be playing into, you know, your thinking on different timings. And then just one more on an early stage asset in the space. What are your thoughts on ALPK1 agonism, if you have any at this point? Thank you so much.

speaker
Mike McElhall
Interim President and Chief Executive Officer

All right. So, Charlie, good morning. Thanks for the question. So, Karen, why don't you handle the question with regards to AB101 and the NEVO-laid to Dravallumab question?

speaker
Dr. Karen Sims
Chief Medical Officer

Yeah, sure, absolutely. So, the data we're sharing thus far is just, you know, the extent of dosing we've completed with AB101. So, it's too early to comment on the dosing that we'll be using in the next portions of the trial. We do have flexibility in the trial in all the different arms to either increase dose, decrease dose, make changes to dosing regimens. So, you know, 25, as reported today, is the highest dose we tested with an excellent safety profile and good pharmacodynamic profile. So, you know, we'll be evaluating, you know, different dosing levels as we move on through the trial. So 25 isn't necessarily a cap. It's just, you know, the data we have available to share, you know, with you today. So, and in terms of the nivolumab data coming out of the 202 study, obviously I can't comment on that. You know, we provided guidance that we'll be sharing the preliminary end of treatment data at the end of the year, the second half of this year. So, you know, that data I can't comment on. But certainly, you know, we look at all of our trials holistically and, you know, certainly, you know, would, as Mike said earlier, you know, move forward or, you know, adapt as we see the data emerging with our trials. But, yeah, to date, I can't comment on anything regarding the nivolumab arm in the 202 study.

speaker
Dr. Mike Sophia
Chief Scientific Officer

And then, Mike, do you want to handle the last question? Yeah, on the ALPK1 question, yeah, we're aware that an abstract just came out on easel on that, you know, Frankly, it just came out, so we are interested in looking at the abstract more fully and obviously seeing the presentation at EASL to get a full understanding of the target.

speaker
Charlie
Analyst, Robert W. Baird & Co.

Gotcha. Great. Thanks so much for the questions, guys. Thanks, Charlie.

speaker
Operator
Conference Operator

Charlie. One moment for our next question. Our next question comes from Roy Buchanan with Citizens JMP.

speaker
Operator
Conference Operator

Please go ahead.

speaker
Roy Buchanan
Analyst, Citizens JMP

Thanks for taking the questions. Obviously, congrats to Mike, Sophia on the plan retirement and it definitely misses deep insights and observations on the calls. You have eight months to get to a functional chair now. Yeah. Just a few questions. So I guess on the 203 trial, I think there's a typo in the slide that says Q48 weeks. And I think Karen said every eight weeks, which makes a lot more sense. So I just want to confirm that. And then I guess is the only variable that the timing of Dervalumab dosing, the arms all look identical. So is that the only variable? There's no difference in actual dose levels or anything else? I guess that's my first question.

speaker
Dr. Karen Sims
Chief Medical Officer

Yeah, no, thanks for the question. So, no, you're absolutely right. The induced saran dosing is 60 milligrams every eight weeks, as we have been studying throughout our phase two program. So, we'll go in and make sure that that's correct in the deck. But yeah, 60 milligrams every eight weeks of induced saran for a 48-week treatment period, as we've also done in some of our other studies. And at the moment, yes, the only difference between the arms is the timing of the induced saran dose. And as I mentioned before, we obviously keep track of of the data with these trials, especially safety data, but we have no intention of changing any of the other parameters of the trial at the moment. Just as mentioned between the three arms, it's just the timing of the two Gevalumab doses.

speaker
Roy Buchanan
Analyst, Citizens JMP

Okay, great. And then follow up on the 101 dose in question. So it's 25 mgs per day, the dose you started part two with. And then for the, I guess the target engagement, I assume that was derived from Did you take circulating blood cells, or where did you look for the target engagement in the patients?

speaker
Dr. Karen Sims
Chief Medical Officer

Right. So, you know, in regards to the dosing of AB101 in Part 2 of the study, again, I can't comment on that. It's ongoing as we speak, and as Mike said earlier in the call, we'll be providing data for the Part 2 portion of the study in the second half of this year. And in regards to the pharmacodynamic assay, yes, it is based on peripheral blood mononuclear cells that are isolated from the subject.

speaker
Roy Buchanan
Analyst, Citizens JMP

Okay, great. And then the last one, maybe you can't answer this either, but it's on the NEVO combo with Berensis vaccine. Can you give us a sense? It looks like the enrollment target went up by a couple patients, 22 versus 20. Can you just tell us where enrollment stands currently in that cohort and about how many patients you can expect? for the data in the second half. Thank you.

speaker
Dr. Karen Sims
Chief Medical Officer

Sure, absolutely. So the target enrollment was 20 subjects for that arm to be consistent with the other two arms of the study. As often happens in these studies, we have screening open to many sites in many countries across the globe, and we can't necessarily control the number of subjects in screening at any one time. So it just happened here that we had a couple of additional subjects that were eligible for the trial and had completed screening, so we did allow them to enter the trial. But that's the only reason for the 22 subjects as opposed to the 20 subjects. And as said previously, we'll be sharing the preliminary end of treatment data from that trial in the second half of this year.

speaker
Roy Buchanan
Analyst, Citizens JMP

Okay, thank you.

speaker
Operator
Conference Operator

Thank you. One moment for our next question. Our next question comes from Kia Nikkei with Chardon.

speaker
Operator
Conference Operator

Please go ahead.

speaker
Kia Nikkei
Analyst, Chardon Partners

Yeah, just some follow-ups on 101 study. In terms of the receptor occupancy, is the assay you're using, is that a standardized or do you have to customize it for this?

speaker
Dr. Mike Sophia
Chief Scientific Officer

Hi, this is Mike Kay. It's an assay we actually developed internally, so it's a proprietary assay that we use for getting that target occupancy readout.

speaker
Kia Nikkei
Analyst, Chardon Partners

Okay. And is the dose response you're seeing, is that consistent with what you'd hoped to see?

speaker
Dr. Mike Sophia
Chief Scientific Officer

Well, you know, I would say in preclinical models, we see 80 to 100 percent, you know, receptor occupancy. So that gave, you know, full efficacy for us. So I think, you know, what we're seeing in the clinical study is very encouraging to us.

speaker
Kia Nikkei
Analyst, Chardon Partners

Okay. And then in the multi-sending dose part of the study, just remind me again, what's the dose frequency? How often is it?

speaker
Dr. Karen Sims
Chief Medical Officer

So it's a total dose duration of seven days, and we do have flexibility within that arm to dose every day or anything different than that, depending on how the data reads out. So, you know, it could be a daily dose. It could be every other day, every third day. You know, that part will be determined as we evaluate the safety PK and PD data that comes in from the different arms of the trial. But it's a seven-day maximum duration.

speaker
Kia Nikkei
Analyst, Chardon Partners

Okay, and when do you expect to be able to advance into part three of the study?

speaker
Dr. Karen Sims
Chief Medical Officer

Right, so it really depends on how these multiple sending dose arms proceed in the healthy subjects. So really, we just need sufficient, again, safety PK and PD data to feel confident to move into that third portion of the trial and to choose a dose to initiate that part of the trial that we think will have impact in these chronic hepatitis B subjects. You know, again, it just depends on the progression of Part 2 of the study. But it is, as we've said earlier, an integrated protocol. So the Part 3 of the study is already approved, and, you know, we would be able to move on, you know, as soon as we are ready with the data.

speaker
Dennis Ding
Analyst, Jefferies LLC

Okay. Thanks.

speaker
Operator
Conference Operator

Thank you. I'm showing no further questions at this time.

speaker
Operator
Conference Operator

I'd now like to turn it back to management for closing remarks.

speaker
Mike McElhall
Interim President and Chief Executive Officer

Great. Thank you. Thanks, everyone, for joining us this morning. We appreciate your continued interest in and support of Arbutus, and we look forward to providing updates to progress the development of our HPV assets. Operator, that concludes our call.

speaker
Operator
Conference Operator

Thank you for your participation in today's conference. This concludes the program. You may now disconnect.

Disclaimer

This conference call transcript was computer generated and almost certianly contains errors. This transcript is provided for information purposes only.EarningsCall, LLC makes no representation about the accuracy of the aforementioned transcript, and you are cautioned not to place undue reliance on the information provided by the transcript.

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